JP4017073B2 - Engine speed control device for work machines - Google Patents

Description

なお旋回用発電電動機１１の出力Ｌeは上部旋回体Ｗ2の負荷つまり旋回負荷Ｌeを表す。
【０１８７】
上記（１１）〜（１３）式は上部旋回体Ｗ2が電気モータによって駆動されることを前提としているが、図１、図２の構成においてインバータ９、旋回用発電電動機１１を取り除き上部旋回体Ｗ2を他のブームＷ1等と同様に油圧アクチュエータによって作動させるようにした場合にも同様なエネルギー保存式の成立する。この場合には上記（１１）、（１２）、（１３）式それぞれに対応して下記（２１）、（２２）、（２３）式が成立する。
【０１８８】
発電電動機出力ＥM＝油機負荷ＬR−エンジン出力ＬD（Ｌc） …（２１）
バッテリ出力ＣD＝発電電動機出力ＥM …（２２）
エンジン出力ＬD（Ｌc）＋バッテリ出力ＣD＝油機負荷ＬR …（２３）
以下に説明する制御は、（１１）、（１２）、（１３）式が成立する場合を前提としているが、上部旋回体Ｗ2を油圧アクチュエータによって作動させることとし（２１）、（２２）、（２３）式が成立している場合にも同様に以下の制御を適用することができる。
【０１８９】
以下図３を併せ参照して説明する。
【０１９０】
・第１０の制御
つぎに図１、図２のハイブリッドシステムにおいてエネルギーロスを低減することができる実施例について説明する。
【０１９１】
すなわちコントローラ７では、電圧センサ６０で検出される電圧から旋回負荷つまり旋回用発電電動機１１の出力Ｌeが演算される。また吐出圧センサ６１で検出される吐出圧Ｐ、斜板角センサ６２で検出される容量Ｄとに基づき油圧ポンプ６の吸収トルクが演算され、このポンプ吸収トルクと、回転センサ１５で検出される油圧ポンプ６の回転数Ｎc（エンジン２の回転数Ｎc）とに基づいて油圧ポンプ６の吸収馬力である油機負荷ＬRが演算される（ステップ１０１）。
【０１９２】
ここで図１、図２の構成でバッテリ１０の充放電ロス、発電電動機４の発電ロス、モータロスを最小にしエネルギーロスを最小にするには、上記（１３）式（エンジン出力ＬD（Ｌc）＋バッテリ出力ＣD＝油機負荷ＬR＋旋回用発電電動機出力Ｌe）において、バッテリ出力ＣDを最小にすればよく、上記（１３）式でバッテリ出力ＣDを零にした下記（１４）式が成立すればよい。
【０１９３】
エンジン出力ＬD＝油機負荷ＬR＋旋回用発電電動機出力Ｌe …（１４）
そこで上記ステップ１０１で演算された油機負荷ＬRと、旋回用発電電動機出力Ｌeを加算したものをアクチュエータ側要求出力とみなし、これら油機負荷ＬR、旋回用発電電動機出力Ｌeからなるアクチュエータ側要求出力を記（１４）式に代入して、エンジン出力ＬDを求め、このエンジン出力ＬDが得られるようにコントローラ７はエンジン２を制御する。
【０１９４】
なお上部旋回体Ｗ2を油圧アクチュエータによって作動させることにした場合には、上記（２３）式でバッテリ出力ＣDを零にした下記（２４）式、
エンジン出力ＬD＝油機負荷ＬR …（２４）
が成立すればよく、上記ステップ１０１で演算された油機負荷ＬRを上記（２４）式に代入して、エンジン出力ＬDを求め、このエンジン出力ＬDが得られるようにエンジン２を制御すればよい。
【０１９５】
具体的なエンジン制御内容は図３のステップ１０３、１０４、１０６を用いて説明される。
【０１９６】
エンジン２は図４に示す目標トルク線Ｌ1に沿って稼動されるものとする。
【０１９７】
すなわち目標トルク線Ｌ1はメモリに記憶されており、この目標トルク線Ｌ1が読み出され（ステップ１０３）、目標トルク線Ｌ1がエンジン出力線Ｇに変換される。つまりエンジン回転数ＮとトルクＴの対応関係Ｌ1は、エンジン出力ＬDとエンジン目標回転数ＮDの対応関係Ｇに変換される。そこで上記（１４）式から演算されたエンジン出力ＬDに対応するエンジン目標回転数ＮDが、エンジン出力線Ｇから求められる（ステップ１０４）。コントローラ７は、エンジン回転数Ｎをエンジン目標回転数ＮDにする回転指令値Ｎ0をガバナ３に出力する。この結果、燃料噴射量が増減され目標トルク線Ｌ1上でマッチングしエンジン回転数Ｎがエンジン目標回転数ＮDに一致しエンジン２でエンジン出力ＬDが発生する（ステップ１０６）。
【０１９８】
上記（１２）式（バッテリ出力ＣD＝発電電動機出力ＥM＋旋回用発電電動機出力Ｌe）において、バッテリ出力ＣDが零であるので、発電電動機４が発電作用している場合には発電電動機４で発生した電力はバッテリ１０に蓄積されることなく旋回用発電電動機１１の回転作動に直接使用される。すなわち発電電動機４で発電が行われると、発電電動機４で発生した交流電力はインバータ８で直流電力に変換されて直流電源線を介して直接他のインバータ９に供給され旋回用発電電動機１１が電動作用する。
【０１９９】
同様に旋回用発電電動機１１が発電作用している場合には旋回用発電電動機１１で発生した電力はバッテリ１０に蓄積されることなく発電電動機４の回転作動に直接使用される。すなわち旋回用発電電動機１１で発電が行われると、旋回用発電電動機１１で発生した交流電力はインバータ９で直流電力に変換されて直流電源線を介して直接他のインバータ８に供給され発電電動機４が電動作用する。
【０２００】
このように第１０の制御によれば、バッテリ出力ＣDが零になるようにエンジン２を制御しているので、バッテリ１０の充放電ロス、発電電動機４の発電ロス、モータロスを最小にしエネルギーロスを最小にでき、エンジン２の燃費を低くすることができる。
【０２０１】
・第１１の制御
つぎにエンジン２の小型化を図ることができる実施例について説明する。
【０２０２】
図４は本実施例におけるエンジン２の最大トルク線Ｒ1、従来のエンジンの最大トルク線Ｒ2（図１４参照）、本実施例の発電電動機４の最大トルク線を本実施例のエンジン２の最大トルク線Ｒ1に加算した最大トルク線Ｒ3、Ｒ′3を示している。最大トルク線Ｒ3は発電電動機４の１時間定格出力時の最大トルク線であり定格点Ｖ3で最大出力が得られる。最大トルク線Ｒ′3は発電電動機４の１分間定格出力時の最大トルク線であり定格点Ｖ′3で最大出力が得られる。
【０２０３】
同図４に示すように本実施例のエンジン２は従来のエンジンよりも小型化にされており、従来の定格点Ｖ2よりもエンジン出力が低い定格点Ｖ1で稼動する。この定格点Ｖ1におけるエンジン２の出力つまり出力上限をＬMとする（図３のステップ１０４参照）。
【０２０４】
ステップ１０１で油機負荷ＬR、旋回用発電電動機出力Ｌeが演算されると、上記（１４）式よりこれら油機負荷ＬR、旋回用発電電動機出力Ｌeを加算したものをアクチュエータ側要求出力とみなし、このアクチュエータ側要求出力ＬR＋Ｌeがエンジン出力ＬDの上限ＬMを超えているか否かが判断される。
【０２０５】
この結果、アクチュエータ側要求出力ＬR＋Ｌeがエンジン出力ＬDの上限ＬMを超えた場合には、超えた負荷相当分の出力（ＬR＋Ｌe−ＬM）が発電電動機４の出力ＥMとして得られるように、コントローラ７からインバータ８に正（＋）極性のトルク指令値ＴDが与えられる。この結果、発電電動機４が電動機として作動し、発電電動機４では、エンジン出力上限ＬMを超えた負荷相当分の出力（ＬR＋Ｌe−ＬM）が発電電動機出力ＥMとして発生する。
【０２０６】
発電電動機４が１時間定格出力で連続稼動している場合には、負荷最大時に定格点Ｖ3でマッチングしエンジン２の出力をアシストしている。図４に示すように定格点Ｖ3では、従来のエンジンの定格点Ｖ2と比較してエンジン出力で同等かそれ以上の馬力を発生している。発電電動機４が１分間定格出力で短時間稼動している場合には、負荷最大時に定格点Ｖ′3でマッチングし１時間定格時の定格点Ｖ3よりも大きい馬力を発生するとともに、従来のエンジンよりも遙かに大きい馬力を発生する。
【０２０７】
なお上部旋回体Ｗ2を油圧アクチュエータによって作動させることにした場合には、上記（２４）式より油機負荷ＬRをアクチュエータ側要求出力とみなし、このアクチュエータ側要求出力ＬRがエンジン出力ＬDの上限ＬMを超えているか否かが判断される。そしてアクチュエータ側要求出力ＬRがエンジン出力ＬDの上限ＬMを超えた場合には、超えた負荷相当分の出力（ＬR−ＬM）が発電電動機４の出力ＥMとして得られるように、コントローラ７からインバータ８に正（＋）極性のトルク指令値ＴDが与えられることになる。
【０２０８】
このように第１１の制御によれば、エンジン２の小型化により原価改善、後方視界改善、騒音低減を図りつつ、作業中に大きな負荷が発生した場合に適切に対処することができる。
【０２０９】
・第１２の制御
つぎにエンジン２の燃費を低減できる実施例について説明する。
【０２１０】
エンジン２の燃費を低減するには前述した第１の制御〜第８の制御で説明したように等燃費曲線Ｍ上で燃料消費率が小さい領域に目標トルク線を設定しこの目標トルク線上でマッチング点が移動するようにエンジン２を制御すればよい。
【０２１１】
以下目標トルク線として図４、図５に示す目標トルク線Ｌ1を想定する（図３のステップ１０３参照）。
【０２１２】
図１０に示すように、コントローラ７からガバナ３に回転数Ｎ0を指示する回転指令値Ｎ0が出力されると、エンジン２の回転数Ｎが回転数Ｎ0にされ目標トルク線Ｌ1上の点Ｖ0でマッチングし、エンジン２はエンジン出力Ｌcを発生する。
【０２１３】
油機負荷ＬRが小さく油機負荷ＬRが実際のエンジン出力Ｌc以下である場合には、上記（１１）式または（２１）式（発電電動機出力ＥM＝油機負荷ＬR−エンジン出力Ｌc）より、コントローラ７は、それらの差分Ｌc−ＬRに相当する出力が発電電動機４に吸収されるよう発電電動機４を制御する。
【０２１４】
これに対して図９に示すように、エンジン２が目標トルク線Ｌ1上のＶ0で稼動しているときに、作業中に大きな油機負荷ＬRが発生し油機負荷ＬRが実際のエンジン出力Ｌcを超えると、上記（１１）式または（２１）式（発電電動機出力ＥM＝油機負荷ＬR−エンジン出力Ｌc）より、コントローラ７は、それらの差分ＬR−Ｌcに相当する出力ＥMを発電電動機４で発生させエンジン出力Ｌcをアシストするように発電電動機４を制御する。
【０２１５】
具体的な制御内容は図３のステップ１０７、１０８、１０９、１１０を用いて説明される。
【０２１６】
コントローラ７には、回転センサ１５の検出値Ｎcが取り込まれこのエンジン実回転数Ｎcに対応する実際のエンジン出力Ｌcがエンジン出力線Ｇから求められる（ステップ１０７）。
【０２１７】
つぎにステップ１０７で演算された実際のエンジン出力Ｌc、ステップ１０１で演算された油機負荷ＬRが、上記（１１）式または（２１）式（発電電動機出力ＥM＝油機負荷ＬR−エンジン出力Ｌc）に代入されて、発電電動機出力ＥMが演算される（ステップ１０８）。
【０２１８】
発電電動機４の実際の回転数Ｎc（エンジン実回転数Ｎc）と発電電動機４のトルクＴD（発生トルク（正）、吸収トルク（負））の対応関係は、発電電動機出力ＥMの大きさ、極性（正、負）毎に各発電電動機一定曲線Ｕとしてメモリに記憶されている。
【０２１９】
そこで上記演算された発電電動機出力ＥMの極性（正、負）と、ＥMの大きさに応じた出力一定曲線が、各発電電動機出力一定曲線Ｕの中から選択される。そして回転センサ１５の検出値Ｎcが取り込まれこの発電電動機実回転数Ｎcに対応するトルクＴDが、上記選択された出力一定曲線上から求められる。たとえば図３の１０９内で破線として示すように、油機負荷ＬRが実際のエンジン出力Ｌcよりも大きく、ＥMの極性が正である場合にはこれらの差分ＬR−Ｌcに相当する大きさのＥMに相当する出力一定曲線Ｕ1が選択され、この選択された出力一定曲線Ｕ1上で発電電動機実回転数Ｎcに対応する正のトルク値ＴD（発生トルク）が求められる（ステップ１０９）。
【０２２０】
つぎにステップ１０９で求められたトルク指令値ＴDが、コントローラ７からインバータ８に出力される。すなわち油機負荷ＬRが実際のエンジン出力Ｌc以下である場合には、発電電動機４にそれらの差分Ｌc−ＬRに相当する出力を吸収させるための負のトルク指令値ＴDがインバータ８に与えられる。この結果、発電電動機４は発電作用し、トルクＴDを吸収し、差分Ｌc−ＬRに相当する出力ＥMを吸収する。
【０２２１】
これに対し油機負荷ＬRが実際のエンジン出力Ｌcを超えている場合には、発電電動機４でそれらの差分ＬR−Ｌcに相当する出力を発生させるための正のトルク指令値ＴDがインバータ８に与えられる。この結果、発電電動機４は電動作用し、トルクＴDを発生し、差分ＬR−Ｌcに相当する出力ＥMを発生する。発電電動機４で発生した出力ＥMが現在のエンジン出力Ｌcが加算されてエンジン出力がアシストされる。発電電動機４によってエンジン２の出力がアシストされると図９に示すように、エンジン２と発電電動機４で発生した馬力と負荷はマッチング点Ｖ4でマッチングし、従来のエンジンと同等かそれ以上の馬力が発生して急増する負荷に対処することができる。
【０２２２】
このように第１２の制御によれば、エンジン２の燃費低減によりエンジン効率の向上を図りつつ、作業中に大きな油機負荷ＬRが発生した場合に適切に対処することができる。
【０２２３】
なお、目標トルク線Ｌ1上でエンジン２が稼動する場合に（第１の制御）、発電電動機４の出力によってエンジン出力をアシストするものとして説明したが、本第１２の制御は、上述した第２の制御、第３の制御、第４の制御、第５の制御、第６の制御、第７の制御、第８の制御のいずれかと組み合わせて実施することができる。すなわち図５、図６、図７に示される領域Ａ1、Ａ2、Ａ3内で設定される目標トルク線上でエンジン２が稼動する場合に発電電動機４の出力によってエンジン出力をアシストしてもよく、図８に示される目標トルク線Ｌ4上でエンジン２が稼動する場合に発電電動機４の出力によってエンジン出力をアシストしてもよい。また図１７に示される目標トルク線Ｌ11上を高負荷側にマッチング点が移動する際に発電電動機４の出力によってエンジン出力をアシストしてもよい。また図１８に示される目標トルク線Ｌ12上を高負荷側にマッチング点が移動する際に発電電動機４の出力によってエンジン出力をアシストしてもよい。
【０２２４】
・第１３の制御
つぎに負荷急上昇時（急加速時）の燃費を低減できる実施例について説明する。
【０２２５】
すなわち上述した第１０の制御と同様にして、図３に示すように、油機負荷ＬR、旋回負荷Ｌeが演算され（ステップ１０１）、これらアクチュエータ側要求出力ＬR＋Ｌeに対応するエンジン出力ＬDが求められ、このエンジン出力ＬDに対応するエンジン２の目標回転数ＮDがエンジン出力線Ｇから求められる（ステップ１０４）。
【０２２６】
このため本来であれば油機負荷ＬRが急上昇している場合には、図３の１０５内でＨ1で示すように、ガバナ３に対してエンジン回転数Ｎを目標回転数ＮDに急加速させる回転指令値ＮDが出力されるのであるが、ターボラグを考慮して、エンジン２のシリンダ内への燃料供給を遅らせる急加速回避制御が実行される。すなわち急加速回避フィルタによって、破線Ｈ2に示すように、エンジン目標回転数ＮDまでエンジン２の回転数Ｎを徐々に上昇させる回転指令値Ｎ0が生成される。たとえばエンジン目標回転数ＮDに到達するまでの時間をたとえば０．５秒程度遅らせる回転指令値Ｎ0が生成される（ステップ１０５）。そしてガバナ３に回転指令値Ｎ0が出力される。この結果、エンジン２のシリンダ内への燃料供給が遅らされ、エンジン２の回転数Ｎが徐々に上昇して目標回転数ＬDに到達しエンジン出力ＬDが発生する（ステップ１０６）。
【０２２７】
このようにターボラグを考慮して、エンジン２のシリンダ内への燃料供給を遅らせる急加速回避制御が実行されるので、負荷急上昇時（急加速時）におけるエンジン２の燃費向上が図られる。
【０２２８】
なお急加速回避フィルタは、加速時にのみ使用され減速時には使用されない。また加速時であっても急加速時のみに使用される。たとえばエンジン最大トルクの１０％程度をしきい値とし、目標回転数ＮDと現在のエンジン回転数Ｎとの差分に相当するトルク増分が、このしきい値を超えている場合に急加速であると判断される。
【０２２９】
急加速回避フィルタを使用しエンジン目標回転数ＮDまでエンジン２の回転数Ｎを徐々に上昇させる急加速回避制御を実行すると、急加速回避制御実行中、急激に増加する油機負荷ＬRに対してエンジン出力が追いつかなくなる。すなわち図３の１０５内に示すように、エンジン目標回転数ＮDと現在ガバナ３に指示されている回転指令値Ｎ0との回転数差分ΔＨに相当するエンジン出力が不足する。
【０２３０】
そこで上述した第１２の制御と同様にして、コントローラ７は、上記回転数差分ΔＨに相当する出力差分ＬR−Ｌcを求め、上記（１１）式または（２１）式（発電電動機出力ＥM＝油機負荷ＬR−エンジン出力Ｌc）より、出力差分ＬR−Ｌcに相当する出力ＥMが発電電動機４で発生しエンジン出力Ｌcをアシストするように発電電動機４を制御する。
【０２３１】
具体的には、実際のエンジン出力Ｌcがエンジン出力線Ｇから演算され（ステップ１０７）、このステップ１０７で演算された実際のエンジン出力Ｌc、ステップ１０１で演算された油機負荷ＬRが、上記（１１）式または（２１）式（発電電動機出力ＥM＝油機負荷ＬR−エンジン出力Ｌc）に代入されて、発電電動機出力ＥMが演算される（ステップ１０８）。そしてこのステップ１０８で演算された発電電動機出力ＥMに対応するトルク指令値ＴDが求められ（ステップ１０９）、このステップ１０９で求められたトルク指令値ＴDがインバータ８に出力されて発電電動機４が電動作用する（ステップ１１０）。この結果発電電動機４から上記回転数差分ΔＨに相当する出力ＥM（＝ＬR−Ｌc）が発生し、エンジン２の出力がアシストされる。
【０２３２】
このように第１３の制御によれば、負荷急上昇時の燃費の低減を図りつつ、急激に増加する負荷に対するエンジン出力の不足分を補填することができる。
【０２３３】
・第１４の制御
つぎにバッテリ１０の残量を確保することができる実施例について説明する。
【０２３４】
第１０の制御で説明したように、エンジン出力ＬDがアクチュエータ側要求出力に一致するようにエンジン２が制御されている場合、つまり下記（１４）式、

あるいは、下記（２４）式、
エンジン出力ＬD＝アクチュエータ側要求出力（油機負荷ＬR） …（２４）
が成立している場合には、エンジン２は発電電動機４を発電作用させる馬力の余裕がなく、バッテリ１０の残量Ｅ（電力蓄積量）が不足するおそれがある。
【０２３５】
本実施例の制御は、図３のステップ１１１、１１２、１１３、１０１、１０２、１０３、１０４、１０６を用いて説明される。
【０２３６】
まず電圧センサ１６の検出値Ｅがバッテリ１０の現残量Ｅとしてコントローラ７に取り込まれ（ステップ１１１）、バッテリ１０の目標残量Ｅpと現残量Ｅとの残量偏差ΔＥGが演算される（ステップ１１２）。
【０２３７】
ここで残留偏差ΔＥGは、遅れフィルタを用いて求められる。たとえば過去２秒間の残量Ｅの平均値を求め、目標残量Ｅpとこの平均値との偏差が残量偏差ΔＥGとされる。これはバッテリ残量Ｅは短時間で大きく変動するため遅れフィルタにより変動を吸収して安定した値を得るためである。また図２３に示すように目標残量Ｅpに所定幅ΔＥ（Ｅpに対して±１/２ΔＥp）の不感帯を設けてもよい。現残量Ｅが目標残量範囲Ｅp±１/２ΔＥp内に入っている場合には残量偏差ΔＥGは０とみなされる（ステップ１１４）。
【０２３８】
つぎにエンジン出力ＬDが、アクチュエータ側要求出力（上記（１４）式におけるＬe＋ＬR）に、残量偏差相当分の出力ΔＥGを加えた値となるように、上記（１４）式が下記（１４）′式のように修正され、

この（１４）′式に、上記ステップ１０１で演算された油機負荷ＬR、旋回用発電電動機出力Ｌe、ステップ１１２で得られた残量偏差相当分の出力ΔＥG
が代入されて、エンジン出力ＬDが求められる（ステップ１０２）。
【０２３９】
以下第１０の制御と同様に、ステップ１０２で求められたエンジン出力ＬDが得られるようにコントローラ７はガバナ３に回転指令値Ｎ0を出力してエンジン２を制御する（ステップ１０３、１０４、１０６）。
【０２４０】
なお上部旋回体Ｗ2を油圧アクチュエータによって作動させることにした場合には、上記（２４）式を、エンジン出力ＬDが、アクチュエータ側要求出力（上記（２４）式におけるＬR）に、残量偏差相当分の出力ΔＥGを加えた値となるように修正した下記（２４）′式、
エンジン出力ＬD＝油機負荷ＬR＋バッテリ残量偏差ΔＥG …（２４）′
を用いてエンジン出力ＬDを求め、このエンジン出力ＬDが得られるようにエンジン２を制御すればよい。
【０２４１】
この結果、負荷に対して、バッテリ１０の残量偏差ΔＥGに相当する余裕をもったエンジン出力が発生する。残量偏差ΔＥG相当分の出力は発電電動機４に吸収され、インバータ８を介してバッテリ１０に残量偏差ΔＥG相当分の電力が蓄積される。このためバッテリ１０の残量が常時、目標残量Ｅp近辺あるいは図２３の目標残量範囲Ｅp±１/２ΔＥpに維持される。
【０２４２】
このため油機負荷ＬR、旋回負荷Ｌeが増大し実際のエンジン出力Ｌcを超えた際には、バッテリ１０から電力が発電電動機４に確実に供給され、発電電動機４が電動作用し発電電動機４の出力ＥMによってエンジン２の出力をアシストすることが保証される。
【０２４３】
このように第１４の制御によれば、バッテリ１０の残量を常時一定レベル以上に保持することができるので、負荷増大時には、発電電動機４によってエンジン出力を確実にアシストすることができる。
【０２４４】
またこの第１４の制御は、前述した第１１の制御、第１２の制御、第１３の制御と適宜組み合わせて実施することができる。
【０２４５】
上述した説明ではアクチュエータ側要求出力を演算しているが、アクチュエータ側要求出力を演算しない実施も可能である。
【０２４６】
この場合は、演算残量偏差ΔＥG相当分の出力を発生させるトルク指令がコントローラ７からインバータ８に与えられる。このため発電電動機４によってエンジン２にかかる負荷は、バッテリ残量偏差ΔＥGに応じたものとなる。エンジン２はガバナ３の動作により、図２０で説明したのと同様に目標トルク線Ｌ1上でエンジン２の出力と負荷とが釣り合いマッチングする。すなわちエンジン出力ＬDは、アクチュエータ側要求出力（旋回用電動機負荷Ｌe＋油機負荷ＬR）と発電電動機４の負荷（バッテリ残量偏差ΔＥG）とを加算した負荷に釣り合い目標トルク線Ｌ1上でマッチングすることになる。
【０２４７】
具体的な制御内容について図２２を参照して説明する。
【０２４８】
・上限ラインＵを超えた場合
図２２で既に説明したように、エンジン実回転数Ｎnrが上限回転数Ｎnmよりも低くなった場合には、噴射量α（Ｎnd−Ｎnr）が上限ラインＵで規定される最大噴射量α（Ｎnd−Ｎnm）を超えたと判断し、上限回転数Ｎnmと実回転数Ｎnrとの差Ｎnm−Ｎnrに応じたトルク α（Ｎnm−Ｎnr）が発電電動機４で発生するようにインバータ８に対して正のトルク指令を与える。すなわちバッテリ残量偏差ΔＥGの値いかんにかかわらず、不足したトルク分α（Ｎnm−Ｎnr）を発生させる正のトルク指令がコントローラ７からインバータ８に与えられる。このため発電電動機４が電動作用しエンジン出力がアシストされる。
【０２４９】
ただし演算残量偏差ΔＥGが負の場合には目標残量Ｅpに対して現残量Ｅが大きくバッテリ１０の蓄電量に余裕がある場合なので、不足したトルク分α（Ｎnm−Ｎnr）に、残量偏差ΔＥG分を加算した出力を発生させる正のトルク指令をインバータ８に与え発電電動機４のアシスト量を増やしてもよい。
【０２５０】
・上限ラインＵを超えない場合
エンジン実回転数Ｎnrが上限回転数Ｎnm以上の場合には、噴射量α（Ｎnd−Ｎnr）が上限ラインＵで規定される最大噴射量α（Ｎnd−Ｎnm）以下と判断し、演算残量偏差ΔＥG相当分の正負の出力を発生させるトルク指令がインバータ８に対して与えられる。このため演算残量偏差ΔＥGが正である場合には、演算残量偏差ΔＥG相当分のトルクを吸収させる負のトルク指令がインバータ８に与えられて、発電電動機４で演算残量偏差ΔＥG相当分のトルクが吸収され発電電動機４が発電作用する。
【０２５１】
また演算残量偏差ΔＥGが負である場合には、演算残量偏差ΔＥG相当分のトルクを発生させる正のトルク指令がインバータ８に与えられて、発電電動機４が電動作用し、発電電動機４で演算残量偏差ΔＥG相当分のトルクが発生する。
【０２５２】
・第１５の制御
つぎにバッテリ１０の残量が下限を下回った場合に緊急措置をとることができる実施例について説明する。
【０２５３】
本実施例におけるエンジン２は、第１１の制御で説明したのと同様に、図４に示すように従来のエンジンの定格点Ｖ2よりもエンジン出力が低い定格点Ｖ1で稼動する小型のエンジン２が使用される。
【０２５４】
同図４に示すように本実施例のエンジン２の定格点Ｖ1は従来のエンジンの定格点Ｖ2よりも等燃費曲線Ｍ上で燃費が小さい（良好な）領域に存在する。
【０２５５】
本実施例の制御は、図３のステップ１１１、１１２、１１３、１１４、１０１、１０２、１０３、１０４、１０６を用いて説明される。
【０２５６】
すなわち第１１の制御と同様にして、バッテリ１０の目標残量Ｅpと現残量Ｅとの残量偏差ΔＥGが演算される（ステップ１１１、１１２、１１３）。つぎに残量偏差ΔＥGが残量偏差しきい値ΔＥ0よりも大きいか否かが判断される。つまりバッテリ１０の現残量Ｅが下限値Ｅ0を下回っているか否かが判断される（ステップ１１４）。この結果、バッテリ残量Ｅが下限値Ｅ0以上であると判断された場合には（ステップ１１４の判断ＮＯ）、ステップ１０２に移行され、以下第１１の制御と同様の制御が実行される。このとき図４に示すように、エンジン２は、第１１の制御で説明したように、定格点をＶ1としエンジン出力の上限値を第１の上限値ＬMとして、エンジン２が制御される（ステップ１０３、１０４、１０６）。これにより通常、エンジン２は、従来のエンジン（定格点Ｖ2）よりもエンジン出力が小さいものの燃費が良好な定格点Ｖ1で稼動する。
【０２５７】
しかしエンジン出力が不足しがちの定格点Ｖ1でエンジン２が常時稼動していると、バッテリ１０への電力蓄積が不足しがちとなりバッテリ残量Ｅが下限値Ｅ0を下回り、バッテリ１０から発電電動機４に電力が供給されなくなるおそれがある。
【０２５８】
そこで、バッテリ残量Ｅが下限値Ｅ0を下回っていると判断された場合には（ステップ１１４の判断ＹＥＳ）、エンジン２の出力の上限値が第１の上限値ＬMよりも大きい第２の上限値Ｌ′Mとなるように、目標トルク線Ｌ1が修正され、エンジン出力線Ｇも書き換えられる。すなわち図４に示すように定格回転数ＮRを、より高い定格回転数Ｎ′Rに上昇させ、定格点Ｖ1を、より高いエンジン出力Ｌ′Mが得られる定格点Ｖ′1に移行させ（図４参照、ステップ１１５）、定格点Ｖ′1と燃費最小点Ｍ1とデセル点Ｎ1とを結ぶ線分が新たな目標トルク線として設定され、この目標トルク線に応じたエンジン出力線が新たに求められる（ステップ１０３、１０４）。
【０２５９】
これにより燃費の点では悪化するものの高いエンジン出力Ｌ′Mが得られる定格点Ｖ′1でエンジン２が稼動する（ステップ１０６）。この結果、上昇した分のエンジン出力が発電電動機４に吸収され、発電電動機４で発電された電力が、インバータ８を介してバッテリ１０に蓄積される。
【０２６０】
このように第１５の制御によれば、通常はエンジン２を燃費が良好な定格点Ｖ1で稼動させつつも、バッテリ１０の残量が下限を下回った場合には、定格点Ｖ1を定格点Ｖ′1に移行させて燃費は悪化するもののエンジン出力を高くする緊急措置をとることで、バッテリ１０で電力が蓄積できるようにし、バッテリ１０から発電電動機４に供給する電力が不足するという事態を回避することができる。
【０２６１】
またこの第１５の制御は、前述した第１２の制御、第１３の制御と適宜組み合わせて実施することができる。
【０２６２】
また上述したエンジン２の出力の上限値を短期的に上昇させる制御は、手動操作で行うようにしてもよい。すなわちオペレータは作業中にエンジン出力の不足を感じると、操作レバー４１ａのノブに設けられたスイッチ４２をオン操作する。コントローラ７に、スイッチ４２がオンされたことを示すオン信号ＯＮが入力されると、コントローラ７では上述したのと同様に目標トルク線、エンジン出力線を修正する処理が行われ（図３のステップ１１５、１０３、１０４）、エンジン２の出力上限値がＬMからＬ′Mに移行され、より高いエンジン出力が得られる定格点Ｖ′1でエンジン２が稼動する（ステップ１０６）。
【０２６３】
なおバッテリ残量Ｅが下限値Ｅ0を下回っていると判断された場合には（ステップ１１４の判断ＹＥＳ）、その旨をオペレータ等に知らしめるべく、コントローラ７からモニタパネル５０に表示指令が出力され、モニタパネル５０の表示画面５０ａに、「バッテリ１０の残量が不足している」旨の警告表示がなされる。
【０２６４】
・第１６の制御
上述した第１５の制御では、バッテリ残量Ｅが下限値Ｅ0を下回っている場合にエンジン２の出力の上限値を短期的に上昇させる緊急措置をとるようにしているが、エンジン２の出力の上限値を上げることで対処するのではなく、建設機械１のアクチュエータの出力を制限することで対処してもよい。
【０２６５】
たとえばバッテリ残量Ｅが下限値Ｅ0を下回っていると判断された場合に、油圧ポンプ６の斜板６ａの最大傾転角を制限しポンプ吸収馬力を制限することが考えられる。また図２４に示すように油圧ポンプ６のＰ−ＱカーブＬＮ1を、より低い吸収馬力となるＰ−ＱカーブＬＮ2に設定してポンプ吸収馬力を制限することが考えられる。またバッテリ残量Ｅが下限値Ｅ0を下回っていると判断された場合に、旋回用電動機１１の出力上限値を低い値に制限することが考えられる。
【０２６６】
これにより油機負荷ＬR、旋回負荷Ｌeが減少し、その減少分だけエンジン２の出力に発電電動機４を発電させる余裕が発生し、発電電動機４で吸収したエンジン出力をバッテリ１０に電力として蓄積することができる。
【０２６７】
・第１７の制御
図１１は建設機械１のエンジン２の出力Ｌc、油機負荷（ポンプ吸収馬力）ＬR、バッテリ（キャパシタ）１０の出力ＣDの状態を示すグラフであり横軸に時間をとり縦軸に出力（ｋＷ）をとっている。図１１は図３に示す制御内容を実施した場合を示している。
【０２６８】
図１１において、エンジン出力Ｌcの特性をＫ1で示し油機負荷ＬRの特性をＫ2で示しバッテリ出力ＣDの特性をＫ3で示している。
【０２６９】
図１１に示すＢ2ではブーム用操作レバー４１ａを最大操作量まで操作して重負荷の掘削作業が行われており、油機負荷Ｋ2がエンジン出力Ｋ1を上回っている。このときバッテリ１０で放電が行われ発電電動機４が電動作用しており油機負荷Ｋ2に対して不足しているエンジン出力を発電電動機４の出力でアシストしている。
【０２７０】
図１１に示すＢ3ではブーム用操作レバー４１ａが戻されて比較的軽負荷の作業が行われており、エンジン出力Ｋ1が油機負荷Ｋ2を上回っている。このとき発電電動機４が発電作用しており、残量偏差ΔＥG相当分の電力がバッテリ１０に充電される。エンジン出力Ｋ1が油機負荷Ｋ2を大きく上回ると、Ｂ5に示すようにバッテリ１０への充電量が大きくなる。
図１１に示すＢ4では旋回用操作レバーが操作され旋回作業が行われており、エンジン出力Ｋ1が油機負荷Ｋ2を上回っている。このとき発電電動機４が発電作用しており、発電電動機４から電力が旋回用発電電動機１１に供給され旋回用発電電動機１１が電動作用している。
【０２７１】
図１１のＢ1に示すように、掘削作業が開始されると操作レバー４１ａが中立位置から操作され油機負荷Ｋ2が上昇するが、エンジン出力Ｋ1は油機負荷Ｋ2に遅れて立ち上がる。これは図３に示すように、油機負荷ＬRを演算し（ステップ１０１）、この油機負荷ＬRに対応するエンジン出力ＬDを求め（ステップ１０２）、このエンジン出力ＬDに対応する目標回転数ＮDを求め（ステップ１０４）、この目標回転数ＮDが得られるようガバナ３が動作することで（ステップ１０５、１０６）、エンジン２の出力が実際に、演算したエンジン出力ＬDまで上昇するが、この間に時間遅れがあり、エンジン２の出力が実際に上昇したときには、既に実際の油機負荷は、演算した油機負荷ＬR以上に上昇しているからである。
【０２７２】
こうした操作レバー投入時における油機負荷Ｋ2とエンジン出力Ｋ1との差は、上記（１１）式（発電電動機出力ＥM＝油機負荷ＬR−実際のエンジン出力Ｌc）に示されるように発電電動機４の出力ＥMによって補填されている。つまりバッテリ１０で放電が行われて発電電動機４が電動作用し発電電動機出力ＥMが発生し、この発電電動機出力ＥMによって、図１１にＢ1で示す実際の油機負荷Ｋ2と実際のエンジン出力Ｋ1との差分がアシストされる。
【０２７３】
このため操作レバー投入時の油機負荷Ｋ2とエンジン出力Ｋ1との差分に相当する最大出力が得られるよう発電電動機４を設計する必要がある。
【０２７４】
したがって操作レバー投入時における油機負荷Ｋ2とエンジン出力Ｋ1との差を小さくすることができれば、発電電動機４の最大出力を小さくでき、その分発電電動機４を小型化することができる。
【０２７５】
以下、発電電動機４を小型化することができる実施例について説明する。
【０２７６】
図１２は操作レバー４１ａの操作特性Ｃを示しており横軸にレバー操作量Ｓをとり、縦軸に作業機（ブーム）の速度をとっている。なおブーム以外のアーム、バケットについても同様である。
【０２７７】
操作レバー４１ａが中立位置から操作されると、油圧ポンプ６の斜板６ａは最小傾転角から上昇し（容量Ｄが上昇し）、ポンプ吸収馬力が上昇する。オペレータは油機負荷の上昇分を予測し負荷上昇分に応じた速度で操作レバー４１ａを操作する。このため操作レバー４１ａを操作する速度から油機負荷ＬRの増分を予測することができる。
【０２７８】
コントローラ７は、操作センサ４１ｂから操作レバー４１ａの操作量Ｓを示す信号を取り込み、図１２に示すように、中立位置から、しきい値Ｓcまで到達する時間τを計測し、単位時間当たりのレバー操作量ΔＳ/τを演算する。
【０２７９】
つぎに単位時間当たりのレバー操作量ΔＳ/τから、回転指令値Ｎ0に上乗せすべき回転数増分ΔＮ（負荷増分予測値）が演算される。
【０２８０】
図３のステップ１０１で油機負荷ＬRが演算され、この油機負荷ＬRから目標回転数ＮDが得られたならば（ステップ１０４）、この目標回転数ＮDに、回転数増分（負荷増分予測値）ΔＮを加算した回転指令値ＮD＋ΔＮ（Ｎ0＋ΔＮ）が生成され（ステップ１０５）、この回転指令値ＮD＋ΔＮ（Ｎ0＋ΔＮ）がガバナ３に出力される。
【０２８１】
この結果操作レバー投入に伴いエンジン出力が迅速に上昇することなり、操作レバー投入時における油機負荷Ｋ2とエンジン出力Ｋ1との差が小さくなる。このため発電電動機４で出し得る最大出力ＥMを小さくでき、その分発電電動機４を小型化することができる。
【０２８２】
なお実施例の制御は、操作レバー投入時など負荷が急上昇する場合に行うことが望ましい。このため回転数増分（負荷増分予測値）ΔＮにしきい値が設定され、回転数増分（負荷増分予測値）ΔＮがしきい値（たとえばエンジン出力で２０ｋｗ/秒相当の増加）を超えた場合に本実施例の制御が行われる。
【０２８３】
また単位時間当たりのレバー操作量ΔＳ/τの代わりにレバー操作量ΔＳから、回転指令値に上乗せすべき回転数増分ΔＮ（負荷増分予測値）を演算してもよい。
【０２８４】
さて図１５はオートデセルの制御内容を説明する図であり、横軸に操作レバーの状態の時間変化（秒）をとり縦軸にエンジン回転数Ｎをとっている。オートデセルの制御は、エンジン回転数Ｎがデセル回転数Ｎ1（１４００ｒｐｍ）以上になっているときに実行される。また図１５は燃料ダイヤル１７で定格回転数ＮRに設定されている場合を基準としている。
【０２８５】
すなわち同図１５に示すように、全ての操作レバーが中立位置に戻されると、エンジン回転数Ｎは、Δｔ1秒で燃料ダイヤル１７で設定されている定格回転数ＮRよりも約１００ｒｐｍ低い第１デセル回転数まで低下する。さらにΔｔ2秒経過するとエンジン回転数Ｎは第１デセル回転数よりも低い第２デセル回転数Ｎ1（以下単にデセル回転数という；１４００ｒｐｍ）までΔｔ3秒で低下し、いずれかの操作レバーが操作されるまでそのデセル回転数Ｎ1を維持する。
【０２８６】
エンジン回転数Ｎがデセル回転数Ｎ1に維持されている状態で、いずれかの操作レバーが中立位置から操作されると、エンジン回転数ＮはΔｔ0（たとえば１秒）で燃料ダイヤル１７で設定されている定格回転数ＮRまで上昇する。
【０２８７】
デセル回転数Ｎ1の１４００ｒｐｍという回転数は、ローアイドル回転数ＮLの１０００ｒｐｍとハイアイドル回転数ＮHの２２００ｒｐｍとの中間の中速の回転数として設定される。この理由は操作レバーが中立位置から操作されたときのエンジン２の応答性を確保するためである。建設機械を設計する際には、操作レバーが中立から操作され油機負荷が投入された際に無負荷状態から定格回転数ＮRに達するに所定時間Δｔ0（たとえば１秒）以内であるということが、品質保証上要求される。デセル回転数Ｎ1を低く設定すると上記要求に応えられないことから、デセル回転数Ｎ1をローアイドル回転数ＮLよりも高い中速の回転数に設定して、操作レバー操作開始時におけるエンジン２の高い応答性を確保している。
【０２８８】
しかし燃費低減の点からみると、デセル回転数Ｎ1を中速回転数（１４００ｒｐｍ）に設定することは、必ずしも適切であるとは言い難い。
【０２８９】
図１６は建設機械で積込み掘削作業を所定のサイクルタイム行ったときの燃費を計測したデータを例示している。図１６の横軸は時間（ｓｅｃ）を示し縦軸は単位時間当たりの燃料消費量（ｋｇ/ｈ）を示している。
【０２９０】
同図１６に示すように掘削積込作業機の消費燃料は、横軸の時間と横軸の燃料消費率を積算した面積ＦＬ1で表され、デセル時つまり全操作レバーが中立位置に戻されデセル回転数Ｎ1に維持されている時の消費燃料は同様にして積算した面積ＦＬ2で表される。作業時の全消費燃料はＦＬ1とＦＬ2とを合計したものである。、全消費燃料ＦＬ1＋ＦＬ2に占めるデセル時の消費燃料ＦＬ2の割合ＦＬ2/（ＦＬ1＋ＦＬ2）は、油圧ポンプの連れ回りトルクもあることから、５〜１０％に達する。以上は燃費について述べたが騒音に関しても同様である。
【０２９１】
以下、操作レバーが中立位置に戻されたときの燃費、騒音を従来よりも低減させつつ、操作レバーが中立位置から操作されたときにエンジンを短時間（たとえば１秒）で目標回転数（定格回転数ＮR）に上昇させることができる実施例について説明する。
【０２９２】
・第１８の制御
まずオペレータは図２に示すモニタパネル５０上で「燃費優先モード」、「応答性優先モード」のいずれかを、選択スイッチ５１、５２のいずれかを選択操作することによって選択する。選択スイッチ５１はデセル回転数Ｎ′1をローアイドル回転数ＮLよりも低い回転数（たとえば７００ｒｐｍ）に設定する選択スイッチであり、選択スイッチ５２はデセル回転数Ｎ′1を上記選択スイッチ５１で選択される回転数よりも高めの回転数に設定する選択スイッチである。
【０２９３】
選択スイッチ５１、５２のいずれかが選択操作されると、選択された内容を示す信号がコントローラ７に入力される。
【０２９４】
一方、コントローラ７には、ブーム用操作レバー４１ａの操作センサ４１ｂを含む各操作センサから操作信号が取り込まれる。
【０２９５】
コントローラ７では操作信号に基づき、全ての操作レバーが中立位置に戻されたか否かが判断される。この結果、全ての操作レバーが中立位置に戻されたと判断された場合には、図１５と同様にして、エンジン回転数Ｎが、選択スイッチ５１、５２によって選択されたデセル回転数Ｎ′1（たとえば７００ｒｐｍ）まで低下させるようガバナ３に回転指令値を出力し、いずれかの操作レバーが操作されるまでそのデセル回転数Ｎ′1を維持する。このため操作レバー中立時における燃費が従来よりも向上する。
【０２９６】
エンジン回転数Ｎがデセル回転数Ｎ′1に維持されている状態で、いずれかの操作レバーが中立位置から操作されたと判断された場合には、コントローラ７はガバナ３に対して、エンジン回転数Ｎを現在の負荷に応じたエンジン回転数ＮDまで（燃料ダイヤル１７で設定されている定格回転数ＮRまで）上昇させるよう回転指令値を出力するとともに、インバータ８に対して正（＋）極性のトルク指令値ＴDを出力し発電電動機４を電動機として作動させる。
【０２９７】
このため無負荷のデセル点Ｎ′1から高負荷の定格点Ｖ1にマッチング点が移動する際に発電電動機４の出力がエンジン２の出力に加算される。発電電動機４の出力によってエンジン出力がアシストされるため、従来と同様に短時間（たとえば約１秒）で応答性よく定格点Ｖ1まで移動する。
【０２９８】
図１３を用いて本実施例の効果について説明する。
【０２９９】
図１３は従来のエンジンの最大トルク線Ｒ2、エンジン２の最大トルク線Ｒ1に発電電動機４の最大トルク線を加算した本実施例の最大トルク線Ｒ3（１時間定格）、Ｒ′3（１分間定格）を比較して示している。
【０３００】
操作レバー操作時にエンジンを加速させる時間は、図１３（ｂ）に示すように最大トルク線から油機負荷γを減算したハッチングで示す面積で規定される。最大トルク線から油機負荷γを減算した面積が大きいほど、エンジンを加速させるトルクの余裕が大きいということであり、より短時間で目標回転数ＮRまで到達させることができる。
【０３０１】
従来最大トルク線Ｒ2から油機負荷γを減算した面積はε1であるのに対して、本実施例の最大トルク線Ｒ′3（１分間定格）から油機負荷γを減算した面積はε1にε3を加算した面積であり、エンジン２を加速させるトルク余裕が従来のエンジンよりも大きい。同様に本実施例の最大トルク線Ｒ3（１時間定格）から油機負荷γを減算した面積はε1にε2を加算した面積であり、エンジン２を加速させるトルク余裕が従来のエンジンよりも大きい。
【０３０２】
しかも発電電動機４はエンジン２と比較して低回転で大きなトルクを発生するのでエンジン回転の立ち上がり時に大きなトルク余裕が生じている。
【０３０３】
このためデセル回転数Ｎ′1を、従来のデセル回転数Ｎ1（１４００ｒｐｍ）よりも低くし更にアイドル回転数ＮLよりも低い極低速の回転数Ｎ1′（たとえば７００ｒｐｍ）に設定したとしても、本実施例の場合には操作レバー４１ａが中立位置から操作されると、加速トルク軌跡αにて示すようにエンジン回転数Ｎは迅速に立ち上がり従来と同様に短時間（たとえば１秒以下）で定格点Ｖ1に到達する。
【０３０４】
このように本実施例によれば、操作レバー中立時のデセル回転数を極低速の回転数Ｎ1′（たとえば７００ｒｐｍ）に設定して、操作レバー操作時のエンジン２の加速を発電電動機４で発生するトルクによってアシストするようにしたので、操作レバーが中立位置に戻されたときの燃費、騒音を従来よりも低減させつつ、操作レバーが中立位置から操作されたときにエンジン２を短時間（たとえば１秒）で目標回転数（定格回転数ＮR）に上昇させることができる。
【０３０５】
ただし選択スイッチ５１によって低めのデセル回転数Ｎ′1が設定された場合には燃費は向上するもののエンジン２の応答性は相対的に悪化し、選択スイッチ５２によって高めのデセル回転数Ｎ′1が設定された場合にはエンジン２の応答性は向上するものの燃費は相対的に悪化する。
【０３０６】
なお選択スイッチ５１、５２によってデセル回転数Ｎ′1を２段階に変化させているが、ダイヤル等によって連続的にデセル回転数Ｎ′1を変化させるようにしてもよい。
【０３０７】
また気象状態やエンジン暖気状態等の条件によってデセル回転数Ｎ′1を低く設定することが望ましくない場合があるので、条件に応じてデセル回転数Ｎ′1を高めに変化させてもよい。
【０３０８】
たとえばエンジン２の冷却水温が検出され冷却水温が規定値（たとえば７０゜Ｃ）以下ではデセル回転数Ｎ′1が高めの回転数に設定される。またバッテリ１０の残量が検出されバッテリ残量が規定値（たとえばＳＯＣ ２０％）以下ではデセル回転数Ｎ′1が高めの回転数に設定される。また大気圧が検出され大気圧が規定値（たとえば７００ｍｍＨｇ）以下ではデセル回転数Ｎ′1が高めの回転数に設定される。またエンジン２に吸入される空気の温度が検出され吸入空気温度が規定値（たとえば４５゜Ｃ）以上ではデセル回転数Ｎ′1が高めの回転数に設定される。
【０３０９】
・第１９の制御
上述した第１８の制御では、操作レバー中立時にエンジン２を回転させているが、エンジン２を停止させてもよい。
【０３１０】
この場合、オペレータは図２に示すモニタパネル５０上で選択スイッチ５３を選択操作して「停止制御モード」を選択する。
【０３１１】
選択スイッチ５３が選択操作されると、停止制御を実行すべきことを示す信号がコントローラ７に入力される。ただし選択スイッチ５３の選択操作は、１回の停止制御のみ有効であることが望ましい。つまり１回の停止制御が実行された後は、再度選択スイッチ５４を選択操作しなければ次回の停止制御を実行しないようにすることが望ましい。なお、ここで「停止制御」とは全ての操作レバーが中立位置に戻された場合にエンジン２を停止させいずれかの操作レバーが中立位置から操作された場合にエンジン２を始動させて負荷に応じた回転数まで上昇させる一連の制御内容のことである。
【０３１２】
一方、コントローラ７には、ブーム用操作レバー４１ａの操作センサ４１ｂを含む各操作センサから操作信号が取り込まれる。
【０３１３】
コントローラ７では操作信号に基づき、全ての操作レバーが中立位置に戻されたか否かが判断される。この結果、全ての操作レバーが中立位置に戻されたと判断された場合には、エンジン２を停止させるよう、つまり燃料供給を停止するようガバナ３に指令を出力し、いずれかの操作レバーが操作されるまでエンジン停止状態を維持する。このため操作レバー中立時における燃費が従来よりも大幅に向上する。
【０３１４】
エンジン２が停止している状態で、いずれかの操作レバーが中立位置から操作されたと判断された場合には、コントローラ７はガバナ３に対して、エンジン回転数Ｎを現在の負荷に応じたエンジン回転数ＮDまで（燃料ダイヤル１７で設定されている定格回転数ＮRまで）上昇させるよう回転指令値を出力するとともに、インバータ８に対して正（＋）極性のトルク指令値ＴDを出力し発電電動機４を電動機として作動させる。
【０３１５】
このため発電電動機４が回転することによってエンジン２が始動し、発電電動機４で発生した出力によってエンジン出力がアシストされて、定格点Ｖ1まで従来と同様に短時間（たとえば約１秒）で応答性よく移動する。
【０３１６】
ここで、図１３（ｂ）に示すように発電電動機４はエンジン２と比較して発電電動機４の起動時（エンジン２の始動時）から大きなトルクを発生するので、エンジン回転の立ち上がり時に大きなトルク余裕が生じている。
【０３１７】
したがってエンジン２を停止させたとしても、操作レバー４１ａが中立位置から操作されると、エンジン回転数Ｎは迅速に立ち上がり従来と同様に短時間（たとえば１秒以下）で定格点Ｖ1に到達することを担保することができる。
【０３１８】
このように本実施例によれば、操作レバー中立時にエンジン２を停止させ、操作レバー操作時に発電電動機４で回転させてエンジン２を始動させエンジン２の加速を発電電動機４で発生するトルクによってアシストするようにしたので、操作レバーが中立位置に戻されたときの燃費、騒音を従来よりも低減させつつ、操作レバーが中立位置から操作されたときにエンジン２を短時間（たとえば１秒）で目標回転数（定格回転数ＮR）に上昇させることができる。
【０３１９】
また発電電動機４は、エンジン始動用のスタータの機能を兼用しているので、スタータを別に設ける必要がなくなり部品点数削減、コスト低減が図られる。また既存のスタータを、エンジン２の出力をアシストできるよう改変して発電電動機４を構成すれば、既存の装置に大きな改変を加えることなく本実施形態のシステムを構成することができる。
【０３２０】
ところで停止制御が実行されるとエンジン２が自動的に停止しエンジン２が自動的に始動するため、オペレータおよび周囲の人間に注意を喚起する必要がある。
【０３２１】
そこで停止制御の実行が開始されると、コントローラ７からブザー１９に対して警報指令が出力され、ブザー１９が鳴動する。これによりオペレータおよび建設機械１の周囲の人間に、「停止制御実行中；操作レバーが操作されたときに作業機が動くので危険である」旨の注意が喚起される。なおスピーカ等でメロディや音声を発生させてもよい。またコントローラ７からモニタパネル５０に表示指令が出力されモニタパネル５０の表示画面５０ａに、同様に「停止制御実行中」であることを示す表示がなされる。また建設機械１の外部に設けた表示器に同様の表示を行うようにしてもよい。表示は単にパイロットランプを点灯ないしは点滅させるだけでもよく、文字、符号、絵などを点灯ないしは点滅させるようにしてもよい。
【０３２２】
また選択スイッチ５３が選択操作されてから停止制御が終了するに至るまで、音または表示で警報を発生させてもよく、エンジン２が停止して待機しているときのみ、音または表示で警報を発生させてもよい。
【０３２３】
また気象状態やエンジン暖気状態等の条件によってエンジン２を停止することが望ましくない場合があるので、条件に応じてエンジン２を停止させないようにしてもよい。
【０３２４】
たとえばエンジン冷却水温が規定値（たとえば７０゜Ｃ）以下の場合、バッテリ残量が規定値（たとえばＳＯＣ ２０％）以下の場合、大気圧が規定値（たとえば７００ｍｍＨｇ）以下の場合、エンジン吸入空気温度が規定値（たとえば４５゜Ｃ）以上の場合には、全ての操作レバーが中立位置に戻されたとしてもエンジン２は停止されず、その代わりに、上述した第１６の制御が実行され、エンジン回転数がデセル回転数Ｎ′1まで低下される。
【０３２５】
・第２０の制御
つぎの上述した第１９の制御の変形例について説明する。
【０３２６】
本実施形態の装置は図２に示すようにＬＳ弁１４を備えている。ＬＳ弁１４は、油圧ポンプ６の吐出圧Ｐと、油圧シリンダ３１の負荷圧ＰLSとの差圧ΔＰが一定差圧ΔＰLSとなるように動作する。
【０３２７】
操作弁２１のスプールの開口面積をＡ、抵抗係数をｃとすると、油圧ポンプ６の吐出流量Ｑは、前述した（２）式（Ｑ＝Ｃ・Ａ・√（ΔＰ））で表される。
【０３２８】
差圧ΔＰはＬＳ弁１４により一定になるのでポンプ流量Ｑは操作弁２１のスプールの開口面積Ａによってのみ変化する。
【０３２９】
作業機用操作レバー４１ａを中立位置から操作すると操作量に応じて操作弁２１のスプールの開口面積Ａが増加し、開口面積Ａの増加に応じてポンプ流量Ｑが増加する。このときポンプ流量Ｑは油機負荷の大きさには影響を受けず作業機用操作レバー４１ａの操作量のみによって定まる。このようにＬＳ弁１４を設けたことにより、ポンプ流量Ｑは負荷によって増減することなくオペレータの意思通りに（操作レバーの操作位置に応じて）変化しファインコントロール性つまり中間操作領域における操作性が向上する。
【０３３０】
油圧ポンプ６の吐出流量Ｑとエンジン２の回転数Ｎと油圧ポンプ６の容量Ｄとの間には、前述した（１）式（Ｑ＝Ｎ・Ｄ）なる関係が成立する。
【０３３１】
ここで油圧ポンプ６の斜板６ａの傾転角に制限がなく最大傾転角で最大容量が得られるものと仮定する。
【０３３２】
作業機用操作レバー４１ａが操作されると、上記（２）式よりスプール開口面積Ａが増大し油圧ポンプ６から、増大した開口面積Ａに応じた大流量Ｑを吐出しようとする。ところが作業機用操作レバー４１ａの操作開始時点ではエンジン停止状態にあり、上記（１）式（Ｑ＝Ｎ・Ｄ）より、エンジン回転立ち上がり時で回転数がほぼ０の極低回転数Ｎにもかかわらず要求される大流量Ｑを吐出させるべくポンプ容量Ｄは最大容量に維持される。
【０３３３】
操作レバー操作時にはエンジン２の加速が発電電動機４で発生するトルクによってアシストされるものの、油圧ポンプ６を最大容量に維持して操作レバー４１ａの操作量に応じた大流量Ｑの圧油を吐出しようとするため、エンジン２のトルクはエンジン２の加速に使われる分の余裕がなく油圧ポンプ６に吸収されて、エンジン回転立ち上がり時の加速性が悪化する。
【０３３４】
そこで本第２０の制御では、作業機用操作レバー４１ａが中立位置から操作された場合には、所定時間に達するまで、またはエンジン回転数が所定回転数に達するまでは、油圧ポンプ６の容量を最大容量よりも小さい値に制限する。具体的には油圧ポンプ６の斜板６ａの傾転角を最大傾転角よりも小さな傾転角に制限する。
【０３３５】
これにより油圧ポンプ６で要求される流量Ｑが制限され、エンジン２のトルクに余裕が生じ、そのトルク余裕分がエンジン２の加速に使われエンジン回転立ち上がり時の加速性が向上する。
【０３３６】
以上のように本第２０の制御によれば、操作レバーのファインコントロール性を向上させつつ、エンジン停止状態から操作レバー投入時のエンジンの加速性を向上させることができる。
【０３３７】
なお第１８の制御、第１９の制御、第２０の制御は、前述した第１、第２、第４、第６〜第１７の制御と適宜組み合わせて実施することができる。すなわち図４等に示されるデセル点Ｎ1が、より回転数の低いデセル点Ｎ′1に変更されて、目標トルク線Ｌ1など、デセル点を通る目標トルク線が設定され、各種制御が実行される。
【図面の簡単な説明】
【図１】図１は実施形態の構成を示す図である。
【図２】図２は図１に示すコントローラに入出力される信号を説明する図である。
【図３】図３は図１に示すコントローラで実行される制御内容を示す図である。
【図４】図４はエンジンのトルク線図を示す図である。
【図５】図５はエンジンのトルク線図を示す図である。
【図６】図６はエンジンのトルク線図を示す図である。
【図７】図７はエンジンのトルク線図を示す図である。
【図８】図８はエンジンのトルク線図を示す図である。
【図９】図９はエンジンのトルク線図を示す図である。
【図１０】図１０はエンジンのトルク線図を示す図である。
【図１１】図１１は図３の制御内容を実行した結果を説明する図である。
【図１２】図１２は操作レバーの操作特性を示す図である。
【図１３】図１３（ａ）、（ｂ）はトルク線図を示す図でエンジンが加速される様子を説明する図である。
【図１４】図１４は従来のエンジンのトルク線図を示す図である。
【図１５】図５はオートデセルを説明する図である。
【図１６】図１６は従来のオートデセル実行時の燃料消費率を説明する図である。
【図１７】図１７はエンジンのトルク線図を示す図である。
【図１８】図１８はエンジンのトルク線図を示す図である。
【図１９】図１９はエンジンのトルク線図を示す図である。
【図２０】図２０はエンジンのトルク線図を示す図である。
【図２１】図２１はエンジンのトルク線図を示す図である。
【図２２】図２２はエンジンのトルク線図を示す図である。
【図２３】図２３はバッテリの目標残量範囲を示す図である。
【図２４】図２４は油圧ポンプのＰ−Ｑカーブを示す図である。
【符号の説明】
２ エンジン
４ 発電電動機
５ 出力軸
６ 油圧ポンプ
７ コントローラ
１０ バッテリ
１１ 旋回用発電電動機
１４ ＬＳ弁
１９ ブザー
４１ａ 操作レバー
５０ａ 表示画面
５１、５２、５３ 選択スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine rotation speed control device for a work machine, and particularly when the operation lever is operated from the neutral position while reducing fuel consumption and noise when the operation lever of the construction machine is returned to the neutral position. The present invention relates to an apparatus that can improve engine responsiveness.
[0002]
[Prior art]
Construction machines such as hydraulic excavators, bulldozers, dump trucks, and wheel loaders are equipped with diesel engines.
[0003]
The configuration of a conventional construction machine 1 will be schematically described with reference to FIG. 1. As shown in FIG. 1, a hydraulic pump 6 is driven using a diesel engine 2 as a drive source. As the hydraulic pump 6, a variable displacement hydraulic pump is used, and the capacity D (cc / rev) is changed by changing the tilt angle of the swash plate 6a. Pressure oil discharged at a discharge pressure P and a flow rate Q (cc / min) from the hydraulic pump 6 is supplied to the hydraulic actuators 31 to 35 such as the boom hydraulic cylinder 31 via the operation valves 21 to 25. By supplying pressure oil to each of these hydraulic actuators 31 to 35, each of the hydraulic actuators 31 to 35 is driven, and a working machine including a boom, an arm, and a bucket connected to each of the hydraulic actuators 31 to 35, a lower traveling body. Operates.
[0004]
An operation lever is provided corresponding to each of the operation valves 21 to 25.
[0005]
When the operation lever is operated from the neutral position, the operation valves 21 to 25 are opened and pressure oil is supplied to the hydraulic actuators 31 to 35.
[0006]
While the construction machine 1 is in operation, the load applied to the work machine and the lower traveling body constantly changes according to the excavated soil quality, the traveling path gradient, and the like. In accordance with this, the load on the hydraulic equipment (hydraulic pump 6) (hereinafter referred to as oil machine load), that is, the load applied to the engine 2 changes.
[0007]
The output (horsepower; kw) of the diesel engine 2 is controlled by adjusting the amount of fuel injected into the cylinder. This adjustment is performed by controlling the governor 3 attached to the fuel injection pump of the engine 1. As the governor 3, an all-speed control type governor is generally used, and the engine speed N and the fuel injection amount (torque T) according to the load so that the target engine speed set by the fuel dial is maintained. ) And are adjusted. That is, the governor 3 increases or decreases the fuel injection amount so that the difference between the target rotational speed and the engine rotational speed is eliminated.
[0008]
FIG. 14 shows a torque diagram of the engine 1. The horizontal axis represents the engine speed N (rpm; rev / min), and the vertical axis represents the torque T (N · m).
[0009]
In FIG. 14, the region defined by the maximum torque line R2 indicates the performance that the engine 1 can produce. The governor 3 controls the engine 2 so that the torque T does not exceed the maximum torque line R2 and reach the exhaust smoke limit, and the engine speed N does not exceed the high idle speed NH and does not become overspeed. The output (horsepower) of the engine 2 becomes maximum at the rated point V2 on the maximum torque line R2. J indicates an equal horsepower curve in which the horsepower absorbed by the hydraulic pump 6 is equal horsepower.
[0010]
When the maximum target rotational speed is set by the fuel dial, the governor 3 adjusts the speed on the maximum speed regulation line Fe connecting the rated point V2 and the high idle point NH.
[0011]
As the oil machine load increases, the matching point at which the output of the engine 2 and the pump absorption horsepower are balanced moves on the highest speed regulation line Fe toward the rated point V2. When the matching point moves toward the rated point V2, the engine speed N is gradually reduced, and at the rated point V2, the engine speed N becomes the rated speed NR.
[0012]
As the target rotational speed set by the fuel dial becomes smaller, regulation lines Fe-1, Fe-2,... Are sequentially determined, and speed regulation is performed on each regulation line.
[0013]
When all the operation levers are returned to the neutral position, the load on the oil machine becomes almost zero. Therefore, the matching point shifts to the no-load high idle point NH on the regulation line Fe, and the engine 2 is relatively high. The motor rotates at a high idle speed NH (for example, 2200 rpm).
[0014]
Opportunities for returning all the control levers to the neutral position frequently occur during the operation of the construction machine, for example, waiting for dumping or waiting for work.
[0015]
On the other hand, construction machinery has recently been required to reduce noise and fuel consumption (hereinafter referred to as fuel efficiency).
[0016]
For this reason, in order to reduce noise and fuel consumption, an auto-decel function that automatically reduces the engine speed to a medium speed (decel speed N1) is built into the construction machine when all control levers are returned to the neutral position. ing.
[0017]
FIG. 15 is a diagram for explaining the control contents of the auto-decel. The horizontal axis represents the time change (seconds) of the state of the operation lever, and the vertical axis represents the engine speed N. The auto-decel control is executed when the engine speed N is equal to or higher than the decel speed N1 (1400 rpm). FIG. 15 is based on the case where the target rotational speed is set to the rated rotational speed NR which is the maximum target rotational speed with the fuel dial.
[0018]
That is, as shown in FIG. 15, when all the operating levers are returned to the neutral position, the engine speed N is about 100 rpm lower than the rated speed NR set by the fuel dial at Δt1 seconds. Decreases to a number. Further, when Δt2 seconds elapse, the engine speed N decreases to a second deceleration speed N1 (hereinafter simply referred to as “decel speed; 1400 rpm”) lower than the first deceleration speed in Δt3 seconds or less, and one of the operation levers is operated. Until that time, the deceleration speed N1 is maintained.
[0019]
If any of the operating levers is operated from the neutral position while the engine speed N is maintained at the deceleration speed N1, the engine speed N is set by the fuel dial at Δt0 seconds (for example, 1 second) or less. It rises to the rated speed NR.
[0020]
[Problems to be solved by the invention]
The deceleration speed N1 of 1400 rpm is set as an intermediate speed between the low idle speed NL (for example, 1000 rpm) and the high idle speed NH (for example, 2200 rpm). The reason for this is to ensure the responsiveness of the engine 2 when the operation lever is operated from the neutral position. When designing a construction machine, the quality is that it is within Δt0 (for example, 1 second) until the rated speed NR is reached from the no-load state when the operating lever is operated from the neutral position and the oil machine load is applied. Required for warranty. If the deceleration speed N1 is set low, the above request cannot be met. Therefore, the deceleration speed N1 is set to a medium speed higher than the low idle speed NL, and the engine 2 at the start of the operation lever operation is high. Responsiveness is ensured.
[0021]
However, from the viewpoint of reducing fuel consumption, it is not necessarily appropriate to set the deceleration speed N1 to the medium speed speed (1400 rpm).
[0022]
FIG. 16 illustrates data obtained by measuring fuel consumption when loading and excavation work is performed with a construction machine for a predetermined cycle time. The horizontal axis in FIG. 16 indicates time (sec), and the vertical axis indicates fuel consumption (kg / h) per unit time.
[0023]
As shown in FIG. 16, the fuel consumption of the excavating and loading work machine is represented by an area FL1 obtained by integrating the time on the horizontal axis and the fuel consumption rate on the horizontal axis. The fuel consumption when the rotational speed N1 is maintained is represented by the area FL2 integrated in the same manner. The total fuel consumed during work is the sum of FL1 and FL2. The ratio FL2 / (FL1 + FL2) of the consumed fuel FL2 at the time of decelerating to the total consumed fuel FL1 + FL2 reaches 5 to 10% due to the accompanying torque of the hydraulic pump.
[0024]
The above is about fuel consumption, but the same applies to noise.
[0025]
The present invention has been made in view of such a situation, and reduces the fuel consumption and noise when the operation lever is returned to the neutral position, and shortens the engine when the operation lever is operated from the neutral position. The problem to be solved is to increase the target rotational speed (rated rotational speed NR) over time (for example, 1 second).
[0026]
In addition, there is a document described in Japanese Patent Application Laid-Open No. 2001-99103 as a document showing a conventional general technical level.
[0027]
In this publication, a clutch is interposed between the engine and the flywheel in order to shorten the start of rotation at the start of the engine, and when the engine is stopped, the clutch is disengaged and the motor is driven to operate the flywheel. An invention is described in which the rotation of the flywheel is maintained so that the wheel does not stop.
[0028]
However, it does not suggest any of the above problems of the present invention.
[0029]
[Means for solving the problems and effects]
The first invention is
A work machine driven by an engine as a drive source according to the operation of the work machine operator;
An electric motor coupled to the output shaft of the engine;
When the work implement operator is returned to the neutral position, the engine speed is reduced to a set rotational speed, and when the work implement operator is operated from the neutral position, the engine rotation speed is reduced. So that the number reaches the target speed within a given time Until the engine speed reaches the target speed Control means for operating the electric motor;
It is characterized by comprising.
[0030]
According to the first invention, as shown in FIG. 2, the electric motor 4 is connected to the output shaft 5 of the engine 2. The work machine W1 is driven according to the operation of the work machine operation lever 41a using the engine 2 as a drive source.
[0031]
FIG. 13 shows a comparison between the conventional maximum torque line R2 when the engine is alone and the maximum torque line R'3 of the present invention in which the maximum torque line of the motor 4 is added to the maximum torque line R1 of the engine 2. . The maximum torque line R'3 is the maximum torque line at which the electric motor 4 operates at a rating for 1 minute.
[0032]
The time for accelerating the engine when the operation lever is operated is defined by the area obtained by subtracting the oil machine load γ from the maximum torque line as shown in FIG. The larger the area obtained by subtracting the oil machine load γ from the maximum torque line, the greater the margin of torque for accelerating the engine, and the target rotational speed NR can be reached in a shorter time.
[0033]
The area obtained by subtracting the oil machine load γ from the conventional maximum torque line R2 is ε1, whereas the area obtained by subtracting the oil machine load γ from the maximum torque line R′3 of the present invention is the area obtained by adding ε3 to ε1. Yes, the torque margin for accelerating the engine 2 is larger than that of the conventional engine. Moreover, since the electric motor 4 generates a large torque at a low rotation as compared with the engine, a large torque margin is generated at the start of the engine rotation.
[0034]
For this reason, even if the rotational speed when the control lever is in the neutral position is set to an extremely low rotational speed N1 ′ (700 rpm) lower than the conventional deceleration rotational speed N1 (1400 rpm) and lower than the idle rotational speed NL, the present invention. In this case, when the operating lever 41a for the work implement is operated from the neutral position, the engine speed N quickly rises as shown by the acceleration torque locus α and is rated in a short time (for example, 1 second or less) as in the conventional case. Point V1 is reached.
[0035]
As described above, according to the present invention, the rotation speed when the operation lever is neutral is set to the extremely low rotation speed N1 ′ (700 rpm), and the acceleration of the engine 2 when the operation lever is operated is assisted by the torque generated by the electric motor 4. As a result, the fuel consumption and noise when the operating lever is returned to the neutral position are reduced as compared with the conventional case, and the engine is set in a short time (for example, 1 second) when the operating lever is operated from the neutral position. The rotational speed (rated rotational speed NR) can be increased.
[0036]
The second invention is the first invention,
Selection means for selecting the set rotational speed
It is characterized by comprising.
[0037]
According to the second invention, as shown in FIG. 2, when the selection switches 51 and 52 of the monitor panel 50 are operated, the set rotational speed when the control lever is neutral changes, for example, in two stages.
[0038]
The third invention is
A work machine driven by an engine as a drive source according to the operation of the work machine operator;
An electric motor coupled to the output shaft of the engine;
When the work implement operator is returned to the neutral position, the engine is stopped, and when the work implement operator is operated from the neutral position, the engine is started and the engine speed is set for a predetermined time. To reach the target speed in Until the engine speed reaches the target speed Control means for operating the electric motor;
It is characterized by comprising.
[0039]
According to the third invention, the engine 2 is stopped when the operation lever is neutral, and the acceleration of the engine 2 is assisted by the torque generated by the electric motor 4 when the operation lever is operated, as in the first invention.
[0040]
Here, as shown in FIG. 13 (b), the electric motor 4 generates a large torque from the start of the electric motor 4 (at the start of the engine 2) as compared with the engine, so that a large torque margin is generated at the start of the engine rotation. ing.
[0041]
Therefore, even if the engine 2 is stopped, when the operating lever 41a for the work implement is operated from the neutral position, the engine speed N quickly rises to the rated point V1 in a short time (for example, 1 second or less) as in the prior art. To reach.
[0042]
Thus, according to the present invention, the engine 2 is stopped when the operation lever is neutral, the engine 2 is started by the torque generated by the electric motor 4 when the operation lever is operated, and the acceleration of the engine 2 is assisted by the torque generated by the electric motor 4. Therefore, while reducing the fuel consumption and noise when the operating lever is returned to the neutral position, the engine speed can be reduced in a short time (for example, 1 second) when the operating lever is operated from the neutral position. (Rated speed NR) can be increased.
[0043]
In addition, since the electric motor 4 of the present invention also functions as a starter for starting the engine, it can be realized without modifying the existing apparatus configuration by modifying the existing starter.
[0044]
The fourth invention is the third invention,
Alarm output means for outputting an alarm during control execution of the control means
It is characterized by comprising.
[0045]
According to the fourth aspect of the invention, as shown in FIG. 2, the warning signal is output when the work implement operating lever 41a is returned to the neutral position, for example, the buzzer 19 sounds. This alerts the operator and people around the construction machine 1 that it is dangerous because the work implement moves when the operation lever is operated.
[0046]
A fifth invention is the third invention,
A hydraulic pump driven by an engine;
A hydraulic actuator that is operated by pressure oil discharged from the hydraulic pump, and means for controlling the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the hydraulic actuator to be a constant differential pressure;
Is provided,
When the work implement operator is operated from a neutral position, the capacity of the hydraulic pump is limited to a value smaller than the maximum capacity until a predetermined time is reached or until the engine speed reaches a predetermined speed. thing
It is characterized by.
[0047]
In the fifth invention, as shown in FIG. 2, the LS valve 14 operates so that the differential pressure ΔP between the discharge pressure P of the hydraulic pump 6 and the load pressure PLS of the hydraulic cylinder 31 becomes a constant differential pressure ΔPLS.
[0048]
When the opening area of the spool of the operation valve 21 is A and the resistance coefficient is c, the discharge flow rate Q of the hydraulic pump 6 is expressed by the following equation (2).
[0049]
Q = C · A · √ (ΔP) (2)
Since the differential pressure ΔP is made constant by the LS valve 14, the pump flow rate Q changes only depending on the opening area A of the spool of the operation valve 21.
[0050]
When the operating lever for work implement 41a is operated from the neutral position, the opening area A of the spool of the operation valve 21 increases according to the operation amount, and the pump flow rate Q increases as the opening area A increases. At this time, the pump flow rate Q is not affected by the size of the oil machine load and is determined only by the operation amount of the work machine operation lever 41a. By providing the LS valve 14 as described above, the pump flow rate Q does not increase / decrease depending on the load and changes according to the operator's intention (according to the operation position of the operation lever). improves.
[0051]
Between the discharge flow rate Q of the hydraulic pump 6, the rotational speed N of the engine 2 and the capacity D of the hydraulic pump 6,
Q = ND (1)
This relationship is established.
[0052]
Here, the tilt angle of the swash plate 6a of the hydraulic pump 6 is not limited, and the maximum capacity can be obtained at the maximum tilt angle.
[0053]
When the work implement operating lever 41a is operated, the spool opening area A increases from the above equation (2), and the hydraulic pump 6 tries to discharge a large flow rate Q corresponding to the increased opening area A. However, when the operation lever 41a for the work implement is started, the engine is stopped, and from the above equation (1) (Q = N · D), even when the engine speed rises, the rotational speed is almost zero, which is almost zero. Regardless, the pump capacity D is maintained at the maximum capacity in order to discharge the required large flow rate Q.
[0054]
Although the acceleration of the engine 2 is assisted by the torque generated by the electric motor 4 when the operation lever is operated, the hydraulic pump 6 is maintained at the maximum capacity and an attempt is made to discharge a large amount of pressure oil Q corresponding to the operation amount of the operation lever 41a. Therefore, the torque of the engine 2 is absorbed by the hydraulic pump 6 without being able to be used for accelerating the engine 2, and the acceleration performance at the start of engine rotation deteriorates.
[0055]
Therefore, in the present invention, when the work machine operation lever 41a is operated from the neutral position, the capacity of the hydraulic pump 6 is made larger than the maximum capacity until a predetermined time is reached or until the engine speed reaches the predetermined speed. Is also limited to a small value. Specifically, the tilt angle of the swash plate 6a of the hydraulic pump 6 is limited to a tilt angle smaller than the maximum tilt angle.
[0056]
As a result, the flow rate Q required from the hydraulic pump 6 is limited, and a margin is generated in the torque of the engine 2, and the torque margin is used for accelerating the engine 2 and the acceleration performance at the start of engine rotation is improved.
[0057]
As described above, according to the present invention, it is possible to improve the acceleration of the engine when the operation lever is turned on from the engine stop state while improving the fine controllability of the operation lever.
[0058]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0059]
In the present embodiment, a description will be given on the assumption that a diesel engine mounted on a construction machine such as a hydraulic excavator, a bulldozer, a dump truck, or a wheel loader is controlled.
[0060]
FIG. 1 shows an overall configuration of a construction machine 1 according to an embodiment. The construction machine 1 is assumed to be a hydraulic excavator. FIG. 2 shows signals input to and output from the controller 7 shown in FIG.
[0061]
The construction machine 1 includes an upper swing body W2 and a lower traveling body, and the lower traveling body includes left and right crawler tracks. A work machine including a boom, an arm, and a bucket is attached to the vehicle body. The boom hydraulic cylinder 31 is driven to operate the boom W1, the arm hydraulic cylinder 32 is driven to operate the arm, and the bucket hydraulic cylinder 33 is driven to operate the bucket. Further, the left crawler belt and the right crawler belt rotate by driving the left travel hydraulic motor 34 and the right travel hydraulic motor 35, respectively.
[0062]
When the swing machinery 12 is driven, the upper swing body W2 rotates through a swing pinion, a swing circle, and the like.
[0063]
The engine 2 is a diesel engine, and its output (horsepower; kw) is controlled by adjusting the amount of fuel injected into the cylinder. This adjustment is performed by controlling the governor 3 attached to the fuel injection pump of the engine 2.
[0064]
As will be described later, the controller 7 outputs a rotation command value N0 for setting the engine speed to the target speed ND to the governor 3, and the governor 3 sets the target speed ND on the target torque line L1 and this value. The fuel injection amount is increased or decreased so that an engine output LD corresponding to the target rotational speed ND is obtained.
[0065]
A generator motor 4 is connected to the output shaft 5 of the engine 2. For example, the drive shaft of the generator motor 4 is connected to the output shaft 5 via a gear or the like. The generator motor 4 performs a power generation operation and an electric operation. That is, the generator motor 4 operates as a motor (motor) and also operates as a generator. The generator motor 4 also functions as a starter for starting the engine 2. When the starter switch is turned on, the generator motor 4 is electrically operated to rotate the output shaft 5 at a low speed (for example, 400 to 500 rpm) to start the engine 2.
[0066]
The generator motor 4 is torque-controlled by an inverter 8. As will be described later, the inverter 8 controls the torque of the generator motor 4 according to the torque command value TD output from the controller 7.
[0067]
A turning generator motor 11 is connected to the drive shaft of the swing machinery 12.
[0068]
The turning generator motor 11 performs a power generation operation and an electric operation. That is, the turning generator motor 11 operates as an electric motor (motor) and also operates as a generator. When the upper swing body W2 stops, the torque of the upper swing body W2 is absorbed and power generation is performed.
[0069]
The turning generator motor 11 is torque-controlled by an inverter 9. The inverter 9 controls the torque of the turning generator motor 11 according to the torque command value output from the controller 7.
[0070]
The inverter 8 and the inverter 9 are each electrically connected to the battery 10 via a DC power supply line. The inverters 8 and 9 are directly electrically connected to each other through a DC power supply line. The controller 7 operates using the battery 10 as a power source.
[0071]
The battery 10 is composed of a capacitor, a storage battery, and the like, and accumulates (charges) the power generated when the generator motor 7 and the turning generator motor 11 generate power. The battery 10 supplies the electric power stored in the battery 10 to the inverter 8 and the inverter 9. In this specification, a capacitor that accumulates electric power as static electricity or a storage battery (battery) such as a lead battery, a nickel metal hydride battery, or a lithium ion battery is referred to as a “capacitor”.
[0072]
A hydraulic pump 6 is connected to the output shaft 5 of the engine 2, and the hydraulic pump 6 is driven when the output shaft 5 rotates. The hydraulic pump 6 is a variable capacity type hydraulic pump, and the capacity D (cc / rev) is changed by changing the tilt angle of the swash plate 6a.
[0073]
Pressure oil discharged from the hydraulic pump 6 at a discharge pressure P and a flow rate Q (cc / min) is used for a boom operation valve 21, an arm operation valve 22, a bucket operation valve 23, a left travel operation valve 24, and a right travel. Supplied to the operation valve 25 for operation.
[0074]
The hydraulic oil output from the boom operation valve 21, the arm operation valve 22, the bucket operation valve 23, the left traveling operation valve 24, and the right traveling operation valve 25 are respectively used as a boom hydraulic cylinder 31 and an arm hydraulic cylinder. 32, supplied to a bucket hydraulic cylinder 33, a left traveling hydraulic motor 34, and a right traveling hydraulic motor 35. As a result, the boom hydraulic cylinder 31, the arm hydraulic cylinder 32, the bucket hydraulic cylinder 33, the left traveling hydraulic motor 34, and the right traveling hydraulic motor 35 are driven to the boom W1, the arm, the bucket, the left crawler track, and the right crawler track, respectively. Operates.
[0075]
FIG. 2 shows the boom hydraulic cylinder 31 as a representative of the hydraulic actuators 31, 32, 33, 34, and 35, and shows a connection mode between the boom operation valve 21 and the boom operation lever device 41. The operation lever device 41 is provided with an operation lever 41a, and a pilot pressure corresponding to the operation amount S is applied to the pilot port of the operation valve 21 as the operation lever 41a is operated from the neutral position.
[0076]
The operation valve 21 is a flow direction control valve, and moves the spool in a direction corresponding to the operation direction of the operation lever 41a, and the spool so that the oil passage is opened by an opening area A corresponding to the operation amount of the operation lever 41a. Move.
[0077]
The servo valve 13 is operated by the signal pressure output from the LS valve 14, and changes the swash plate 6a of the hydraulic pump 6 via the servo piston.
[0078]
A discharge pressure P of the hydraulic pump 6 and a load pressure PLS of the hydraulic cylinder 31 are respectively applied to the pilot ports facing the LS valve 14. A spring 14a for applying a constant differential pressure ΔPLS is provided on the side on which the load pressure PLS acts.
[0079]
The LS valve 14 operates so that the differential pressure ΔP between the discharge pressure P of the hydraulic pump 6 and the load pressure PLS of the hydraulic cylinder 31 becomes a constant differential pressure ΔPLS, and a signal pressure corresponding to the valve position is supplied to the servo valve 13. Output. As a result, the servo valve 13 changes the swash plate 6a of the hydraulic pump 6 to change the discharge pressure P of the hydraulic pump 6, and the differential pressure ΔP between the discharge pressure P of the hydraulic pump 6 and the load pressure PLS of the hydraulic cylinder 31 is kept constant. Adjust to differential pressure ΔPLS.
[0080]
When the opening area of the spool of the operation valve 21 is A and the resistance coefficient is c, the discharge flow rate Q of the hydraulic pump 6 is expressed by the following equation (2).
[0081]
Q = C · A · √ (ΔP) (2)
Since the differential pressure ΔP is made constant by the LS valve 14, the pump flow rate Q changes only depending on the opening area A of the spool of the operation valve 21.
[0082]
When the operating lever for work implement 41a is operated from the neutral position, the opening area A of the spool of the operation valve 21 increases according to the operation amount, and the pump flow rate Q increases as the opening area A increases. At this time, the pump flow rate Q is not affected by the size of the oil machine load and is determined only by the operation amount of the work machine operation lever 41a. By providing the LS valve 14 as described above, the pump flow rate Q does not increase / decrease depending on the load and changes according to the operator's intention (according to the operation position of the operation lever). improves.
[0083]
Although the case where there is one hydraulic actuator has been described, in the case where a plurality of hydraulic actuators 31 to 35 are provided, the LS valve 14 is configured so that the discharge pressure P of the hydraulic pump 6 and the load pressure of the hydraulic actuators 31 to 35 are. (Maximum load pressure) The operation is performed so that the differential pressure ΔP with respect to PLS becomes a constant differential pressure ΔPLS.
[0084]
Further, when a plurality of operation valves 21 to 25 are operated simultaneously, a pressure compensation valve is provided so that a large amount of pressure oil is not supplied to a light load hydraulic actuator, and the front-rear differential pressure ΔP of each operation valve 21 to 25 is the same. Adjusted to
[0085]
The operation lever device 41 is provided with an operation amount S from the neutral position of the operation lever 41a, and an operation sensor 41b for detecting that the operation lever 41a is located at the neutral position. The operation amount S detected by the operation sensor 41b is neutral. An operation signal indicating the position is input to the controller 7.
[0086]
A switch 42 for “digging force up control” is provided on the knob of the operation lever 41a. When the switch 42 is turned on, an on signal ON is input to the controller 7.
[0087]
The monitor panel 50 is provided with selection switches 51, 52, and 53 for selecting each control mode and stop control mode of auto-decel, and a selection switch 54 for selecting "power mode" and "economy mode" as work modes. , 55 are arranged. The selection switches 51 and 52 are switches for selecting “fuel consumption priority mode” and “responsiveness priority mode” as the auto-decel control mode, respectively. The selection switch 53 is a switch for selecting “stop control mode”. The selection switches 54 and 55 are switches that respectively select “power mode” and “economy mode” as work modes performed by the construction machine. When any one of the selection switches 51, 52, and 53 is selected as an auto-decel control mode, a signal indicating the selected content is input to the controller 7. When any of the selection switches 54 and 55 is selected as a work mode, a signal indicating the selected content is input to the controller 7.
[0088]
In the fuel dial 17, an instruction rotational speed of the engine 2 is set. When the fuel dial 17 is operated to the maximum, the rated speed NR is set as the indicated speed. A signal indicating the setting contents of the fuel dial 17 is input to the controller 7.
[0089]
A rotation sensor 15 for detecting the current actual rotational speed Nc (rpm) of the engine 2 is attached to the output shaft 5 of the engine 2. A signal indicating the engine speed Nc detected by the rotation sensor 15 is input to the controller 7.
[0090]
The hydraulic pump 6 is provided with a discharge pressure sensor 61 for detecting the discharge pressure P of the hydraulic pump 6 and a swash plate angle sensor 62 for detecting the capacity D of the hydraulic pump 6 as a swash plate tilt angle. ing. A signal indicating the discharge pressure P detected by the discharge pressure sensor 61 and a signal indicating the capacitance D detected by the swash plate angle sensor 62 are respectively input to the controller 7.
[0091]
The load of the upper swing body W2, that is, the swing load Le can be measured by detecting the voltage of the DC power supply line connecting the battery 10 and the inverter 9 with the voltage sensor 60. A signal indicating the voltage detected by the voltage sensor 60 is input to the controller 7 and the turning load Le is calculated from the input voltage. The turning load may be detected directly by attaching a torque sensor to the upper turning body W2.
[0092]
When the battery 10 is composed of a capacitor, the voltage stored in the battery 10 can be detected by detecting the voltage of the battery 10 with the voltage sensor 16. A signal indicating the remaining amount E of the battery 10 detected by the voltage sensor 16 is input to the controller 7.
[0093]
The controller 7 outputs a rotation command value N0 to the governor 3 to increase / decrease the fuel injection amount so as to obtain the target rotation speed according to the current oil machine load, Adjust the torque T.
[0094]
Further, the controller 7 outputs a generator motor torque command value TD to the inverter 8 to cause the generator motor 4 to generate power or operate. When a negative (-) polarity torque command value TD is given from the controller 7 to the inverter 8, the inverter 8 controls the generator motor 4 to operate as a generator. That is, a part of the output torque generated in the engine 2 is transmitted to the drive shaft of the generator motor 4 through the engine output shaft 5 to absorb the torque of the engine 2 and generate power. The AC power generated by the generator motor 4 is converted to DC power by the inverter 8 and is stored (charged) in the battery 10 via the DC power line. Alternatively, AC power generated by the generator motor 4 is converted into DC power by the inverter 8 and supplied directly to the other inverter 9 through the DC power line.
[0095]
Further, when a positive (+) polarity torque command value TD is given from the controller 7 to the inverter 8, the inverter 8 controls the generator motor 4 to operate as a motor. In other words, electric power is output (discharged) from the battery 10, and the DC power accumulated in the battery 10 is converted into AC power by the inverter 8 and supplied to the generator motor 4 to rotate the drive shaft of the generator motor 4. Alternatively, DC power supplied from another inverter 9 is converted into AC power by the inverter 8 and supplied to the generator motor 4 to rotate the drive shaft of the generator motor 4. As a result, torque is generated in the generator motor 4, and this torque is transmitted to the engine output shaft 5 via the drive shaft of the generator motor 4 and added to the output torque of the engine 2 (the output of the engine 2 is assisted). ) This added output torque is absorbed by the hydraulic pump 6.
[0096]
The power generation amount (absorption torque amount) and the motor drive amount (assist amount; generated torque amount) of the generator motor 4 vary according to the contents of the torque command value TD.
[0097]
The upper swing body W2 is operated by operating a swing operation lever (not shown).
[0098]
In response to the operation of the turning operation lever, the controller 7 outputs to the inverter 9 a positive torque command value for operating the upper turning body W2. When a torque command value having a positive (+) polarity is given from the controller 7 to the inverter 9, the inverter 9 controls the turning generator motor 11 to operate as a motor. That is, the DC power stored in the battery 10 or the DC power supplied from another inverter 8 is converted into AC power by the inverter 9 and supplied to the turning generator motor 11 to rotate the drive shaft of the swing machinery 12 to rotate the upper part. The turning body W2 is turned.
[0099]
When the upper swing body W2 stops, the torque generated by the swing machinery 12 is transmitted to and absorbed by the drive shaft of the swing generator motor 11 to generate power. The alternating current power generated by the turning generator motor 11 is converted into direct current power by the inverter 9 and accumulated (charged) in the battery 10 via the direct current power line. Alternatively, the AC power generated by the turning generator motor 11 is converted to DC power by the inverter 9 and supplied directly to the other inverter 8 via the DC power line.
[0100]
In addition, the controller 7 outputs an alarm command to the buzzer 19 to sound the buzzer 19, outputs a display command to the monitor panel 50, and displays the internal state, control status, alarm content, etc. of the construction machine 1 on the display screen 50a of the monitor panel 50. Is displayed.
[0101]
The contents of control executed by the controller 7 will be described below.
[0102]
・ First control
FIG. 4 shows a torque diagram of the engine 2. The horizontal axis represents the engine speed N (rpm; rev / min), and the vertical axis represents the torque T (N · m).
[0103]
In FIG. 4, the region defined by the maximum torque line R1 shows the performance that the engine 2 can produce. At the high idle point NH, the engine 2 becomes unloaded, and the engine speed N becomes the high idle speed NH. The high idle speed NH is the maximum speed when the engine 2 is unloaded. The output (horsepower) of the engine 2 becomes maximum at the rated point V1 on the maximum torque line R1, and the engine speed N becomes the rated speed NR. J indicates an equal horsepower curve in which the horsepower absorbed by the hydraulic pump 6 is equal horsepower.
[0104]
In FIG. 4, M indicates an equal fuel consumption curve. The fuel consumption is minimized at M1 that is the valley of the equal fuel consumption curve M, and the fuel consumption increases toward the outside from the fuel consumption minimum point M1. The fuel consumption in this case refers to the amount of fuel consumed per hour and output of 1 kW, and is an index of the efficiency of the engine 2.
[0105]
At the decel point N1 at the time of auto-decel, the engine 2 becomes unloaded and the engine speed N becomes the decel speed N1. Here, auto-decel means that when all the operation levers including the operation lever 41a are returned to the neutral position, the engine speed N is reduced to the medium-speed decel speed N1, and one of the operation levers is operated from the neutral position. In this case, the engine speed N is increased from the deceleration speed N1 to a speed corresponding to the load.
[0106]
When the fuel dial 17 is operated to the maximum, the maximum engine speed is set to the rated engine speed NR, the rated point V1 corresponding to the rated engine speed NR, the fuel efficiency minimum point M1, Is set as the target torque line L1.
[0107]
The controller 7 outputs to the governor 3 an instruction rotation speed command value N0 for adjusting the speed on the target torque line L1. As a result, the governor 3 increases or decreases the fuel injection amount in accordance with the oil machine load, and makes it match at a point on the target torque line L1.
[0108]
As the oil machine load increases, the matching point at which the output of the engine 2 and the pump absorption horsepower are balanced moves on the target torque line L1 toward the rated point V1. When the matching point moves to the rated point V1 side, the engine torque T and the engine speed N gradually increase. At the rated point V1, the engine output becomes maximum and the engine speed N becomes the rated speed NR.
[0109]
When the fuel dial 17 is operated and the engine speed N0 smaller than the rated engine speed NR is set as the engine maximum engine speed, the point V0 corresponding to the engine speed N0, the minimum fuel consumption point M1, and the decel point N1 during auto-decel Is set as the target torque line.
[0110]
The controller 7 outputs a rotation command value N0 to the governor 3 in order to match a point on the target torque line L1 with the rotation speed N0 as the upper limit rotation speed. As a result, the governor 3 increases or decreases the fuel injection amount according to the oil machine load, and moves the matching point on the target torque line L1 with the rotation speed N0 as the upper limit rotation speed.
[0111]
As the oil machine load increases, the matching point moves on the target torque line L1 toward the rated point V1 and reaches the point V0.
[0112]
The controller 7 and the governor 3 control the engine 2 as follows so as to match at a point on the target torque line L1.
[0113]
The contents shown in FIG. 19 are set and stored in the controller 7. FIG. 19 corresponds to FIG.
[0114]
As shown in FIG. 19, the controller 7 is set with respective matching target rotational speeds N0t, N1t,... N1t ... NR (rated points) on the target torque line L1. Each matching rotation speed N0t, N1t,... N1t,... NR (rated point) is set in association with each indicated rotation speed N0d, N1d,. Since the engine 2 has friction horsepower, the point at which the fuel injection amount becomes 0 exists below the engine torque 0 line in the torque diagram.
[0115]
An upper limit line U that defines the maximum fuel injection amount is set between the engine maximum torque line R1 and the target torque line L1 on the torque diagram.
[0116]
Each upper limit rotational speed N0m, N1m,... Nnm... Nem on the upper limit line U is set in correspondence with each indicated rotational speed N0d, N1d,.
[0117]
Further, each upper limit rotational speed N0m, N1m,... Nnm, Nem, each matching target rotational speed N0t, N1t,... N1t,. Each regulation line F0, F1,... Fn... Fe (the highest speed regulation line) is set.
[0118]
The controller 7 stores map data (N0d, N0t, N0m), (N1d, N1t, N1m),... (Nnd, Nnt, Nnm). I remember it.
[0119]
Now, it is assumed that the load applied to the engine 2 is reduced and the actual rotational speed Nnr of the engine 2 is higher than the matching target rotational speed Nnt.
[0120]
In this case, as shown in FIG. 20, the governor 3 injects fuel of the injection amount α (Nnd−Nnr) corresponding to the difference between the commanded rotational speed Nnd and the actual rotational speed Nnr into the engine 2.
[0121]
In addition, the controller 7 gives the governor 3 a command to change the indicated rotational speed Nnd to N′nd by an amount corresponding to the difference Nnt−Nnr between the matching target rotational speed Nnt and the actual rotational speed Nnr.
[0122]
As a result, the regulation line moves from Fn to a regulation line F′n that is on the same horsepower curve J as the current rotational speed Nnr and passes on the target torque line L1, and a matching point N ′ on the regulation line F′n. Matching is performed at nt (matching target rotation speed N′nt). In this way, the matching point moves from the point Nnt on the target torque line L1 to the point N′nt having a lower horsepower.
[0123]
Although the case where the load applied to the engine 2 is reduced has been described, the matching point is moved along the target torque line L1 according to the change of the load in the same manner when the load applied to the engine 2 is increased.
[0124]
As described above, the matching points can be sequentially moved along the target torque line L1 as the load of the engine 2 changes.
[0125]
In the present embodiment, as described above, the control “injects the fuel of the injection amount α (Nnd−Nnr) according to the difference between the indicated rotational speed Nnd and the actual rotational speed Nnr” into the engine 2 and the “matching target” Control is performed to change the indicated rotational speed Nnd to N′nd by an amount corresponding to the difference Nnt−Nnr between the rotational speed Nnt and the actual rotational speed Nnr. In order to prevent the interference between the two controls and to make an accurate match, the control of “changing the indicated rotational speed Nnd to N′nd by an amount corresponding to the difference Nnt−Nnr from the rotational speed Nnr” It is desirable to execute the operation sufficiently late as compared with the control of “injecting fuel of the injection amount α (Nnd−Nnr) into the engine 2 according to the difference from the actual rotational speed Nnr”.
[0126]
Next, the operation when the load on the engine 2 suddenly increases will be described.
[0127]
As shown in FIG. 21, when the load of the engine 2 is suddenly increased and the engine 2 is accelerated, the difference Nnd−Nnr between the indicated rotational speed Nnd and the actual rotational speed Nnr increases. Here, in order to satisfy the required acceleration, a fuel having a large injection amount α (Nnd−Nnr) corresponding to the difference between the indicated rotational speed Nnd and the actual rotational speed Nnr is supplied from the governor 3 to the engine 2. If the fuel is injected, the amount of air is relatively insufficient with respect to the fuel, the combustion efficiency of the engine 2 is deteriorated, and black smoke is exhausted.
[0128]
Therefore, the injection amount α (Nnd−Nnr) corresponding to the difference Nnd−Nnr between the command rotational speed Nnd and the actual rotational speed Nnr exceeds the maximum injection amount α (Nnd−Nnm) defined by the upper limit line U. In this case, the governor 3 causes the engine 2 to inject the limited maximum fuel injection amount α (Nnd−Nnm) into the engine 2, and the controller 7 causes the generator motor 4 to be electrically operated and the remaining torque (α (Nnd−Nnr ) −α (Nnd−Nnm) = α (Nnm−Nnr)) is assisted by the generator motor 4.
[0129]
Specifically, as shown in FIG. 22, when the actual engine speed Nnr becomes lower than the upper limit speed Nnm, the controller 7 sets the maximum injection amount α (Nnd−Nnr) defined by the upper limit line U. It is determined that the injection amount α (Nnd−Nnm) has been exceeded, and the inverter 8 is configured so that a torque α (Nnm−Nnr) corresponding to the difference Nnm−Nnr between the upper limit rotational speed Nnm and the actual rotational speed Nnr is generated in the generator motor 4. Is given a positive torque command.
[0130]
As described above, since the output of the engine 2 is assisted by the generator motor 4 at the time of sudden load, it is possible to improve engine efficiency and reduce black smoke while maintaining acceleration.
[0131]
Next, the effect of the first control will be described.
[0132]
FIG. 14 shows a conventional engine control method.
[0133]
That is, when the maximum target rotational speed is set by the fuel dial 17, the governor 3 adjusts the speed on the fastest regulation line Fe connecting the rated point V2 and the high idle point NH. As the oil machine load increases, the matching point moves to the rated point V2 side on the fastest regulation line Fe. When the matching point moves toward the rated point V2, the engine speed N is gradually reduced, and at the rated point V2, the engine speed N becomes the rated speed NR. In addition, as the target rotational speed set by the fuel dial 17 becomes smaller, the regulation lines Fe-1, Fe-2,... Are sequentially determined, and the speed is adjusted on each regulation line.
[0134]
What is required of the engine 2 of the construction machine 1 is responsiveness of the engine 2 when the load of the oil machine becomes high. That is, the shorter the time required for the matching point to move from the no-load high idle point NH to the maximum load rated point V2 on the regulation line Fe, the better the engine response.
[0135]
In this regard, in the conventional engine control method, as described above, when the matching point moves on the regulation line Fe to the high load side, the engine speed N is gradually reduced. As the engine speed N decreases, the output accumulated on the flywheel of the engine 2 momentarily goes out, and the apparent output becomes larger than the actual output of the engine 2. For this reason, it is said that the conventional engine control method has good responsiveness.
[0136]
As described above, according to the conventional engine control method, the engine 2 can follow the oil machine load with good responsiveness, but there is a problem that the fuel efficiency is large (poor) and the pump efficiency is low. Pump efficiency is the efficiency of the hydraulic pump 6 defined by volumetric efficiency and torque efficiency.
[0137]
As is clear from FIG. 14, the regulation line Fe corresponds to a region where the fuel consumption is relatively high on the equal fuel consumption curve M. Therefore, according to the conventional engine control method, there is a problem that fuel efficiency is large (poor) and undesirable in terms of engine efficiency.
[0138]
On the other hand, in the case of the variable displacement hydraulic pump 6, generally, if the discharge pressure P is the same, the larger the pump capacity D (swash plate tilt angle), the higher the volume efficiency and torque efficiency, and the higher the pump efficiency. Are known.
[0139]
As is clear from the following equation (1), if the flow rate Q of the pressure oil discharged from the hydraulic pump 6 is the same, the pump capacity D is increased as the rotational speed N of the engine 2 is decreased. Can do. For this reason, if the engine 2 is slowed down, the pump efficiency can be increased.
[0140]
Q = ND (1)
Therefore, in order to increase the pump efficiency of the hydraulic pump 6, the engine 2 may be operated in a low speed region where the rotational speed N is low.
[0141]
However, as is apparent from FIG. 14, the regulation line Fe corresponds to a high speed region of the engine 2. For this reason, the conventional engine control method has a problem that the pump efficiency is low.
[0142]
On the other hand, according to the first control, as shown in FIG. 4, a target torque line L1 is set in a region where the fuel consumption is relatively small on the equal fuel consumption curve M, and matching is performed along the target torque line L1. The point moves.
[0143]
For this reason, according to the first control, the engine 2 operates in an area where the fuel consumption is small (good), so that the engine efficiency can be increased.
[0144]
Further, the target torque line L1 shown in FIG. 4 corresponds to a region where the rotational speed N of the engine 2 is lowered and the capacity D of the hydraulic pump 6 is increased as compared with the regulation line Fe of FIG.
[0145]
According to the first control, the efficiency of the hydraulic pump 6 can be increased because the matching point moves on the target torque line L1 where the rotational speed N of the engine 2 decreases and the capacity D of the hydraulic pump 6 increases.
[0146]
In the case of the present embodiment, the LS valve 14 is provided. If the operation amount S of the operation lever 41a is the same, the flow rate Q is the same. From the above equation (1) (Q = N · D), As the rotational speed N of the engine 2 is lowered, the pump capacity D can be increased and the pump efficiency can be increased.
[0147]
According to the first control, the matching point moves on the target torque line L1 that lowers the rotational speed N of the engine 2 and increases the capacity D of the hydraulic pump 6, so During operation, the pump capacity D can always be kept high, and the pump efficiency can be kept high. As described above, according to the first control, by combining with the LS valve 14, it is possible to realize an operation characteristic capable of maintaining high pump efficiency while improving fine controllability.
[0148]
By the way, when the matching point moves on the target torque line L1 from the no-load state to the high load side, that is, the rated point V1 side as shown by the arrow in FIG. 4, the engine rotation differs from the conventional engine control method shown in FIG. The number N rises.
[0149]
If the rotational speed at no load on the target torque line L1 is set to a very low speed instead of the medium speed deceleration speed N1, that is, if the engine moves to the low idle point NL side from the deceleration point N1, the engine It takes a long time to accelerate the flywheel No. 2 from the extremely low speed to the rated speed NR of the high speed, and the responsiveness of the engine 2 is lowered. Conversely, if the no-load speed is set to be higher than the medium speed deceleration speed N1, that is, if it moves to the high idle point NH side from the deceleration speed N1, the time required to reach the rated speed NR can be shortened. 2 responsiveness is improved. However, when the no-load rotation speed is set to the high speed side, the engine 2 operates in a region where the fuel consumption is large (bad) as in the conventional case (FIG. 14).
[0150]
In consideration of such a trade-off, the no-load rotational speed on the target torque line L1 is set to the medium speed deceleration rotational speed N1.
[0151]
The deceleration speed N1 (for example, 1400 rpm) is a short time (for example, about 1 second) from the no-load state to the rated speed NR when any of the operating levers is operated from the neutral position and the oil machine load is applied. This is the no-load speed that is compensated for.
[0152]
Therefore, by setting the deceleration speed N1 to the engine speed at no load, it takes a short time for the matching point to move from the deceleration point N1 to the rated point V1 with a high load. For this reason, as described above, the matching point is moved in a region where the fuel consumption is good, thereby improving the fuel efficiency and increasing the engine efficiency. Can be prevented.
[0153]
・ Second control
In the first control, a line segment connecting the rated point V1, the minimum fuel consumption point M1, and the decel point N1 is set as the target torque line L1 and matched on the target torque line L1, but strictly, The line segment that passes through the vicinity of the minimum fuel consumption point M1 may not be a line segment that passes through the minimum fuel consumption point M1, and the target torque line may be set and matched. In addition, the line segment that does not strictly pass through the decel point N1 may be set as a target torque line, and matching may be performed on the target torque line.
[0154]
Specifically, as shown in FIG. 5, the target torque line may be set in the vicinity of the target torque line L1 and in a region A1 where the engine speed is approximately ± 300 rpm. For example, a line segment connecting the rated point V1, the fuel efficiency minimum point M1, and the fuel efficiency minimum point M1 and a no-load point having the same rotational speed can be set as the target torque line L'1. If the target torque line is set in the area A1, the same effect as the first control can be obtained.
[0155]
・ Third control
In the first control, a line connecting the rated point V1, the minimum fuel consumption point M1, and the decel point N1 is set as the target torque line L1 and matched on the target torque line L1. Any target torque line including at least a line segment connecting V1 and the fuel efficiency minimum point M1 may be used, and the target torque line does not necessarily have to pass through the deceleration point N1 or the vicinity of the deceleration point N1 as shown in FIG.
[0156]
For example, as shown in FIG. 6, a line segment obtained by extending a line segment connecting the rated point V1 and the fuel efficiency minimum point M1 may be set as the target torque line L2 and matched on the target torque line L2.
[0157]
Further, as shown in FIG. 6, the target torque line may be set in the vicinity of the target torque line L2 and in a region A2 where the engine speed is approximately ± 300 rpm.
[0158]
According to the third control, although the responsiveness of the engine 2 is somewhat lower than that in the first control, the engine 2 operates in a region where the fuel consumption is small (good) as in the first control. Efficiency can be increased. Further, since the engine 2 is slowed down more than the first control, the engine 2 can be operated in a region where the pump efficiency is higher, and the efficiency of the hydraulic pump 6 can be further increased.
[0159]
・ Fourth control
In the first control, a line segment connecting the rated point V1, the minimum fuel consumption point M1, and the decel point N1 is set as the target torque line L1, and the matching point is moved on the target torque line L1. As shown in FIG. 7, a line connecting the rated point V1 and the decel point N1 may be set as the target torque line L3, and matching may be performed on the target torque line L3.
[0160]
In addition, as shown in FIG. 7, the target torque line may be set in the vicinity of the target torque line L3 and in a region A3 where the engine speed is approximately ± 300 rpm.
[0161]
According to the fourth control, since the engine 2 is faster than the first control, the responsiveness of the engine 2 can be further improved although the pump efficiency is somewhat reduced.
[0162]
-Fifth control
In the first control, a line segment connecting the rated point V1, the fuel efficiency minimum point M1, and the decel point N1 is set as the target torque line L1 and matched on the target torque line L1, but FIG. As shown in FIG. 5, a line segment parallel to the engine speed axis that maintains the same torque as the rated point V1 may be set as the target torque line L4 and matched on the target torque line L4.
[0163]
According to the fifth control, although the responsiveness of the engine 2 is reduced as compared with the first control, the engine 2 operates in a region where the fuel consumption is small (good) as in the first control. Can be increased. In addition, since the engine 2 is slowed more than the first control and the third control, the engine 2 can be operated in a region where the pump efficiency is higher, and the efficiency of the hydraulic pump 6 can be further increased.
[0164]
・ Sixth control
In the first control, a line segment connecting the rated point V1, the fuel efficiency minimum point M1, and the decel point N1 is set as a target torque line L1, and matching is performed on the target torque line L1, but FIG. As shown in FIG. 4, the fuel efficiency minimum points V1, V12, V13, etc. at which the fuel consumption rate is minimum on the equal horsepower curves J1, J2, J3 of the torque diagram or the vicinity of the fuel efficiency minimum points V1, V12, V13,. The engine 2 may be controlled in the same manner as the first control described above so that the target torque line L11 that passes through is set and matching is made at a point on the target torque line L11.
[0165]
According to the sixth control, when the matching point moves on the target torque line L11 as the load of the engine 2 changes, the engine 2 can always be operated in a state where the fuel consumption is minimum or almost minimum. As a result, engine efficiency can be increased.
[0166]
・ Seventh control
Further, as shown in FIG. 18, the fuel efficiency minimum points V1, V12, V13, etc. at which the fuel consumption rate is minimum on the respective equi-horsepower curves J1, J2, J3... Of the torque diagram or the fuel efficiency minimum points V1, V12, V13. ... With respect to the first target torque line L11 passing through the vicinity, a second target torque line L12 in which the rotational speed N of the engine 2 decreases and the capacity D of the hydraulic pump 6 increases is set. The engine 2 may be controlled in the same manner as the first control described above so as to match in this point.
[0167]
When matching is performed at a point on the second target torque line L12, the fuel consumption is larger than when matching is performed at a point on the first target torque line L11, but the rotation speed is lower and the hydraulic pump 6 Since the capacity D of the hydraulic pump 6 can be increased, the efficiency of the hydraulic pump 6 is improved, and a larger engine horsepower can be obtained at the same engine speed. As a result, the overall efficiency of the engine 2 and the hydraulic pump 6 is improved, and work can be performed efficiently with larger engine power.
[0168]
・ Eighth control
Further, as shown in FIG. 18, the fuel efficiency minimum points V1, V12, V13, etc. at which the fuel consumption rate is minimum on the respective equi-horsepower curves J1, J2, J3... Of the torque diagram or the fuel efficiency minimum points V1, V12, V13. ... a first target torque line L11 passing through the vicinity, and a second target in which the rotational speed N of the engine 2 decreases and the capacity D of the hydraulic pump 6 increases with respect to the first target torque line L11. It is also possible to set the torque line L12 and select both in accordance with the work contents performed by the construction machine 1.
[0169]
On the monitor panel 50 of FIG. 2, selection switches 54 and 55 for “power mode” and “economy mode” are provided. When one of the first target torque line L11 and the second target torque line L12 is selected by the selection switches 54 and 55, the controller 7 controls the governor so as to match at a point on the selected target torque line. A command is given to 3 to control the engine 2.
[0170]
When the second target torque line L12 is selected, matching is performed at a point on the second target torque line L12. When matching is performed at a point on the second target torque line L12, the fuel consumption is larger than when matching is performed at a point on the first target torque line L11. Since the capacity D of the hydraulic pump 6 can be increased, the efficiency of the hydraulic pump 6 is improved, and a larger engine horsepower can be obtained at the same engine speed. As a result, the overall efficiency of the engine 2 and the hydraulic pump 6 is improved, and the work can be efficiently performed with a larger engine power (power mode).
[0171]
When the first target torque line L11 is selected, matching is performed at a point on the first target torque line L11. When matching is performed at a point on the first target torque line L11, the engine power is reduced and the working efficiency is reduced as compared with the case of matching at a point on the second target torque line L12. The engine 2 can be operated in a state where the fuel consumption is minimum or almost minimum, and the engine efficiency can be increased (economy mode).
[0172]
Therefore, even if the work situation changes, the engine 2 can always be operated in the optimum mode by selection, and the change of the work situation can be dealt with.
[0173]
The first to eighth controls described above have been described on the assumption that they are implemented in a hybrid system that uses the engine 2 and the generator motor 4 together as the drive source shown in FIGS. The above first control to eighth control may be performed in a system in which only 2 is a drive source for the oil machine load.
[0174]
・ Ninth control
According to the first control described above, the engine speed 2 when the matching point moves to the high load side on the target torque line L1 because the medium-speed deceleration speed N1 is set to the engine speed at no load. However, the responsiveness of the engine 2 may be further improved by assisting the engine output by the generator motor 4.
[0175]
That is, as indicated by an arrow in FIG. 4, when the controller 7 determines that the matching point moves in the direction in which the oil machine load applied to the output shaft 5 increases on the target torque line L1, the controller 7 and the inverter 8 Is given a positive (+) polarity torque command value TD, and the generator motor 4 operates as an electric motor.
[0176]
For example, the deviation between the target engine speed (instructed speed) NR and the actual engine speed Nc detected by the rotation sensor 15 is obtained, and the matching point is determined from this deviation in the direction in which the oil machine load increases on the target torque line L1. It can be judged that it moves.
[0177]
Further, when the oil machine load LR is measured and the oil machine load LR is increasing, it may be determined that the matching point moves in the direction in which the oil machine load increases on the target torque line L1, and the operation sensor 41b. When the operation lever operation amount S detected in (2) is large, it may be determined that the matching point moves in the direction in which the oil machine load increases on the target torque line L1.
[0178]
In the ninth control, the output of the generator motor 4 is added to the output of the engine 2 when the matching point moves from the no-load decel point N1 to the high-load rated point V1. The time for accelerating the flywheel of the engine 2 is shortened by the amount that the engine output is assisted by the output of the generator motor 4, and can be moved to the rated point V1 in a short time. For this reason, according to the ninth control, the responsiveness of the engine 2 can be further enhanced as compared with the first control.
[0179]
The ninth control is combined with any of the second control, the third control, the fourth control, the fifth control, the sixth control, the seventh control, and the eighth control described above. Can be implemented. That is, the engine output is assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line set in the areas A1, A2 and A3 shown in FIGS. Alternatively, the engine output may be assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line L4 shown in FIG. Further, the engine output may be assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line L11 shown in FIG. Further, the engine output may be assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line L12 shown in FIG.
[0180]
Here, a relational expression of energy in the apparatus configuration of FIGS. 1 and 2 will be described.
[0181]
The following energy conservation relational expression is established among the output EM of the generator motor 4, the oil machine load LR, and the engine output LD (or Lc).
[0182]
Generator motor output EM = oil machine load LR-engine output LD (Lc) (11)
However, in the above equation (11), the polarity of EM when the generator motor 4 is electrically operated is positive. The above equation (11) can be rewritten as follows.
[0183]
Engine output LD (Lc) + generator motor output EM = oil machine load LR (11a)
The following energy conservation relational expression is established among the output CD of the battery 10, the output EM of the generator motor 4, and the output Le of the generator motor 11 for turning.
[0184]
Battery output CD = Generator motor output EM + Rotating generator motor output Le (12)
However, when the battery 10 is discharged in the above equation (12), that is, when the electric power is output from the battery 10, the polarity of CD is positive, and the polarity of EM when the generator motor 4 is electrically operated is positive. The polarity of Le when the turning generator motor 11 is electrically operated is positive.
[0185]
If the generator motor output EM is deleted using the above equation (11) (or equation (11a)) and equation (12), the output LD of the engine 2, the output CD of the battery 10, the oil machine load LR, the turning generator motor Between 11 outputs Le, the following energy conservation relational expression holds.
[0186]

The output Le of the turning generator motor 11 represents the load of the upper turning body W2, that is, the turning load Le.
[0187]
The above formulas (11) to (13) are based on the premise that the upper swing body W2 is driven by an electric motor, but the upper swing body W2 is removed by removing the inverter 9 and the swing generator motor 11 in the configuration of FIGS. The same energy conservation formula is also established when the actuator is operated by a hydraulic actuator in the same manner as other booms W1 and the like. In this case, the following equations (21), (22), and (23) are established corresponding to the equations (11), (12), and (13), respectively.
[0188]
Generator motor output EM = oil machine load LR-engine output LD (Lc) (21)
Battery output CD = Generator motor output EM (22)
Engine output LD (Lc) + battery output CD = oil machine load LR (23)
The control described below is based on the assumption that the equations (11), (12), and (13) are satisfied. However, the upper swing body W2 is operated by a hydraulic actuator (21), (22), ( Similarly, the following control can be applied when the equation (23) holds.
[0189]
This will be described below with reference to FIG.
[0190]
・ Tenth control
Next, an embodiment capable of reducing energy loss in the hybrid system of FIGS. 1 and 2 will be described.
[0191]
That is, the controller 7 calculates the turning load, that is, the output Le of the turning generator motor 11 from the voltage detected by the voltage sensor 60. Further, the absorption torque of the hydraulic pump 6 is calculated based on the discharge pressure P detected by the discharge pressure sensor 61 and the capacity D detected by the swash plate angle sensor 62, and this pump absorption torque and the rotation sensor 15 detect. Based on the rotational speed Nc of the hydraulic pump 6 (the rotational speed Nc of the engine 2), an oil machine load LR which is an absorption horsepower of the hydraulic pump 6 is calculated (step 101).
[0192]
In order to minimize the energy loss by minimizing the charge / discharge loss of the battery 10, the power generation loss of the generator motor 4, and the motor loss in the configuration of FIGS. 1 and 2, the above equation (13) (engine output LD (Lc) + In the case of battery output CD = oil machine load LR + turning generator motor output Le), the battery output CD may be minimized, and the following expression (14) in which the battery output CD is set to zero in the above expression (13) may be satisfied. .
[0193]
Engine output LD = oil machine load LR + turning generator motor output Le (14)
Therefore, the sum of the oil machine load LR calculated in step 101 and the turning generator motor output Le is regarded as the actuator side required output, and the actuator side required output composed of the oil machine load LR and the turning generator motor output Le. Is substituted into the equation (14) to determine the engine output LD, and the controller 7 controls the engine 2 so that the engine output LD is obtained.
[0194]
When the upper swing body W2 is actuated by a hydraulic actuator, the following equation (24) in which the battery output CD is set to zero in the above equation (23),
Engine output LD = oil machine load LR (24)
The engine load LR calculated in step 101 is substituted into the above equation (24) to obtain the engine output LD, and the engine 2 is controlled so that the engine output LD is obtained. .
[0195]
Specific engine control contents will be described using steps 103, 104, and 106 in FIG.
[0196]
It is assumed that the engine 2 is operated along the target torque line L1 shown in FIG.
[0197]
That is, the target torque line L1 is stored in the memory, the target torque line L1 is read (step 103), and the target torque line L1 is converted into the engine output line G. That is, the correspondence L1 between the engine speed N and the torque T is converted into the correspondence G between the engine output LD and the engine target speed ND. Therefore, the target engine speed ND corresponding to the engine output LD calculated from the above equation (14) is obtained from the engine output line G (step 104). The controller 7 outputs to the governor 3 a rotation command value N0 that sets the engine speed N to the engine target speed ND. As a result, the fuel injection amount is increased / decreased and matched on the target torque line L1, the engine speed N matches the engine target speed ND, and the engine output LD is generated in the engine 2 (step 106).
[0198]
In the above equation (12) (battery output CD = generator motor output EM + turning generator motor output Le), since the battery output CD is zero, it is generated in the generator motor 4 when the generator motor 4 is generating power. The electric power is directly stored in the rotating generator motor 11 without being stored in the battery 10. That is, when the generator motor 4 generates power, the AC power generated by the generator motor 4 is converted into DC power by the inverter 8 and supplied directly to the other inverter 9 through the DC power line, and the turning generator motor 11 is electrically driven. Works.
[0199]
Similarly, when the turning generator motor 11 is generating electric power, the electric power generated by the turning generator motor 11 is directly stored in the battery 10 and used directly for rotating the generator motor 4. That is, when power is generated by the turning generator motor 11, the AC power generated by the turning generator motor 11 is converted into DC power by the inverter 9 and supplied directly to the other inverter 8 through the DC power line, and the generator motor 4. Works electrically.
[0200]
Thus, according to the tenth control, since the engine 2 is controlled so that the battery output CD becomes zero, the charge / discharge loss of the battery 10, the power generation loss of the generator motor 4, and the motor loss are minimized to reduce the energy loss. The fuel consumption of the engine 2 can be reduced.
[0201]
-Eleventh control
Next, an embodiment capable of reducing the size of the engine 2 will be described.
[0202]
4 shows the maximum torque line R1 of the engine 2 in this embodiment, the maximum torque line R2 of the conventional engine (see FIG. 14), and the maximum torque line of the generator motor 4 of this embodiment. Maximum torque lines R3 and R'3 added to the line R1 are shown. The maximum torque line R3 is the maximum torque line when the generator motor 4 is rated for 1 hour, and the maximum output is obtained at the rated point V3. The maximum torque line R'3 is the maximum torque line at the rated output of the generator motor 4 for 1 minute, and the maximum output is obtained at the rated point V'3.
[0203]
As shown in FIG. 4, the engine 2 of this embodiment is smaller than the conventional engine, and operates at the rated point V1 where the engine output is lower than the conventional rated point V2. The output of the engine 2 at the rated point V1, that is, the output upper limit is set to LM (see step 104 in FIG. 3).
[0204]
When the oil machine load LR and the turning generator motor output Le are calculated in step 101, the sum of the oil machine load LR and the turning generator motor output Le is regarded as the actuator-side required output from the above equation (14). It is determined whether or not the actuator-side required output LR + Le exceeds the upper limit LM of the engine output LD.
[0205]
As a result, when the actuator-side required output LR + Le exceeds the upper limit LM of the engine output LD, the controller 7 outputs the output corresponding to the excess load (LR + Le−LM) as the output EM of the generator motor 4. A torque command value TD having a positive (+) polarity is applied to the inverter 8. As a result, the generator motor 4 operates as a motor, and in the generator motor 4, an output corresponding to a load exceeding the engine output upper limit LM (LR + Le−LM) is generated as the generator motor output EM.
[0206]
When the generator motor 4 is continuously operated at the rated output for one hour, the output of the engine 2 is assisted by matching at the rated point V3 when the load is maximum. As shown in FIG. 4, at the rated point V3, a horsepower equal to or higher than the rated point V2 of the conventional engine is generated in the engine output. When the generator motor 4 is operating for a short time at the rated output for 1 minute, it matches at the rated point V'3 when the load is maximum and generates a horsepower that is greater than the rated point V3 at the 1 hour rated time. Generates much greater horsepower than
[0207]
When the upper swing body W2 is actuated by a hydraulic actuator, the hydraulic equipment load LR is regarded as an actuator-side required output from the above equation (24), and this actuator-side required output LR is the upper limit LM of the engine output LD. It is determined whether or not it exceeds. When the actuator-side required output LR exceeds the upper limit LM of the engine output LD, an output corresponding to the excess load (LR−LM) is obtained from the controller 7 as an inverter 8 so that the output EM of the generator motor 4 is obtained. Is given a torque command value TD having a positive (+) polarity.
[0208]
As described above, according to the eleventh control, when the engine 2 is downsized, cost reduction, rear view improvement, and noise reduction can be achieved, and an appropriate action can be taken when a large load occurs during the work.
[0209]
・ Twelfth control
Next, an embodiment that can reduce the fuel consumption of the engine 2 will be described.
[0210]
In order to reduce the fuel consumption of the engine 2, a target torque line is set in a region where the fuel consumption rate is small on the iso-fuel consumption curve M as described in the first to eighth controls, and matching is performed on the target torque line. The engine 2 may be controlled so that the point moves.
[0211]
Hereinafter, the target torque line L1 shown in FIGS. 4 and 5 is assumed as the target torque line (see step 103 in FIG. 3).
[0212]
As shown in FIG. 10, when the rotation command value N0 for instructing the rotational speed N0 is output from the controller 7 to the governor 3, the rotational speed N of the engine 2 is set to the rotational speed N0 and at a point V0 on the target torque line L1. After matching, the engine 2 generates an engine output Lc.
[0213]
When the oil machine load LR is small and the oil machine load LR is less than or equal to the actual engine output Lc, the above equation (11) or (21) (generator motor output EM = oil machine load LR−engine output Lc) The controller 7 controls the generator motor 4 so that the output corresponding to the difference Lc−LR is absorbed by the generator motor 4.
[0214]
On the other hand, as shown in FIG. 9, when the engine 2 is operating at V0 on the target torque line L1, a large oil machine load LR is generated during the operation, and the oil machine load LR becomes the actual engine output Lc. Exceeds the above equation (11) or (21) (generator motor output EM = oil engine load LR−engine output Lc), the controller 7 determines the output EM corresponding to the difference LR−Lc as the generator motor 4. And the generator motor 4 is controlled so as to assist the engine output Lc.
[0215]
Specific control contents will be described using steps 107, 108, 109, and 110 in FIG.
[0216]
The controller 7 takes in the detected value Nc of the rotation sensor 15 and obtains the actual engine output Lc corresponding to the actual engine speed Nc from the engine output line G (step 107).
[0217]
Next, the actual engine output Lc calculated in step 107 and the oil machine load LR calculated in step 101 are expressed by the above equation (11) or (21) (generator motor output EM = oil machine load LR−engine output Lc). ) And the generator motor output EM is calculated (step 108).
[0218]
The correspondence relationship between the actual rotational speed Nc of the generator motor 4 (engine actual rotational speed Nc) and the torque TD (generated torque (positive), absorbed torque (negative)) of the generator motor 4 depends on the magnitude and polarity of the generator motor output EM. Each (positive, negative) is stored in the memory as a constant curve U for each generator motor.
[0219]
Accordingly, a constant output curve corresponding to the calculated polarity (positive or negative) of the generator motor output EM and the magnitude of EM is selected from each generator motor output constant curve U. Then, the detection value Nc of the rotation sensor 15 is taken in, and the torque TD corresponding to the actual generator motor speed Nc is obtained from the selected constant output curve. For example, as indicated by a broken line in 109 of FIG. 3, when the oil machine load LR is larger than the actual engine output Lc and the polarity of EM is positive, EM having a magnitude corresponding to the difference LR−Lc is obtained. A constant output curve U1 corresponding to is selected, and a positive torque value TD (generated torque) corresponding to the actual generator motor speed Nc is obtained on the selected constant output curve U1 (step 109).
[0220]
Next, the torque command value TD obtained in step 109 is output from the controller 7 to the inverter 8. That is, when the oil machine load LR is equal to or less than the actual engine output Lc, a negative torque command value TD for causing the generator motor 4 to absorb an output corresponding to the difference Lc−LR is given to the inverter 8. As a result, the generator motor 4 generates power, absorbs the torque TD, and absorbs the output EM corresponding to the difference Lc−LR.
[0221]
On the other hand, when the oil machine load LR exceeds the actual engine output Lc, the positive torque command value TD for causing the generator motor 4 to generate an output corresponding to the difference LR−Lc is supplied to the inverter 8. Given. As a result, the generator motor 4 is electrically operated to generate a torque TD and an output EM corresponding to the difference LR−Lc. The output EM generated by the generator motor 4 is added to the current engine output Lc to assist the engine output. When the output of the engine 2 is assisted by the generator motor 4, the horsepower and load generated by the engine 2 and the generator motor 4 are matched at the matching point V4 as shown in FIG. It is possible to cope with a load that suddenly increases due to the occurrence of the problem.
[0222]
As described above, according to the twelfth control, it is possible to appropriately cope with a case where a large oil machine load LR is generated during work while improving the engine efficiency by reducing the fuel consumption of the engine 2.
[0223]
Note that, when the engine 2 is operated on the target torque line L1 (first control), the engine output is assisted by the output of the generator motor 4, but this twelfth control is the second control described above. The third control, the fourth control, the fifth control, the sixth control, the seventh control, and the eighth control can be combined. That is, the engine output may be assisted by the output of the generator motor 4 when the engine 2 operates on the target torque line set in the areas A1, A2, and A3 shown in FIGS. The engine output may be assisted by the output of the generator motor 4 when the engine 2 operates on the target torque line L4 shown in FIG. Further, the engine output may be assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line L11 shown in FIG. Further, the engine output may be assisted by the output of the generator motor 4 when the matching point moves to the high load side on the target torque line L12 shown in FIG.
[0224]
・ 13th control
Next, an embodiment that can reduce the fuel consumption at the time of sudden increase in load (during rapid acceleration) will be described.
[0225]
That is, as in the tenth control described above, as shown in FIG. 3, the oil machine load LR and the turning load Le are calculated (step 101), and the engine output LD corresponding to the actuator side required output LR + Le is obtained. The target rotational speed ND of the engine 2 corresponding to the engine output LD is obtained from the engine output line G (step 104).
[0226]
For this reason, when the oil machine load LR is suddenly increasing, the engine speed N is rapidly accelerated to the target speed ND with respect to the governor 3 as indicated by H1 in 105 of FIG. Although the command value ND is output, sudden acceleration avoidance control for delaying the fuel supply into the cylinder of the engine 2 is executed in consideration of the turbo lag. That is, the rapid acceleration avoidance filter generates a rotation command value N0 that gradually increases the rotational speed N of the engine 2 up to the engine target rotational speed ND, as indicated by a broken line H2. For example, a rotation command value N0 is generated that delays the time required to reach the target engine speed ND by about 0.5 seconds, for example (step 105). Then, the rotation command value N0 is output to the governor 3. As a result, the fuel supply into the cylinder of the engine 2 is delayed, the engine speed N of the engine 2 gradually increases, reaches the target engine speed LD, and the engine output LD is generated (step 106).
[0227]
In this way, taking into account the turbo lag, the sudden acceleration avoidance control for delaying the fuel supply into the cylinder of the engine 2 is executed, so that the fuel efficiency of the engine 2 can be improved when the load suddenly increases (during rapid acceleration).
[0228]
The sudden acceleration avoidance filter is used only during acceleration and not used during deceleration. Even during acceleration, it is used only during rapid acceleration. For example, when the threshold value is about 10% of the maximum engine torque, and the torque increment corresponding to the difference between the target engine speed ND and the current engine speed N exceeds this threshold value, the acceleration is rapid. To be judged.
[0229]
When the sudden acceleration avoidance control that uses the sudden acceleration avoidance filter to gradually increase the engine speed N to the target engine speed ND is executed, the oil load LR increases rapidly during the sudden acceleration avoidance control. Engine output cannot keep up. That is, as indicated by 105 in FIG. 3, the engine output corresponding to the rotational speed difference ΔH between the engine target rotational speed ND and the rotational command value NO instructed to the current governor 3 is insufficient.
[0230]
Therefore, similarly to the above-described twelfth control, the controller 7 obtains an output difference LR-Lc corresponding to the rotation speed difference ΔH, and the above expression (11) or (21) (generator motor output EM = oil machine From the load LR−engine output Lc), the generator motor 4 is controlled such that an output EM corresponding to the output difference LR−Lc is generated in the generator motor 4 and assists the engine output Lc.
[0231]
Specifically, the actual engine output Lc is calculated from the engine output line G (step 107), and the actual engine output Lc calculated in step 107 and the oil machine load LR calculated in step 101 are Substitute into equation 11 or equation (21) (generator motor output EM = oil engine load LR-engine output Lc), and generator motor output EM is calculated (step 108). Then, a torque command value TD corresponding to the generator motor output EM calculated in this step 108 is obtained (step 109), and the torque command value TD obtained in this step 109 is output to the inverter 8 so that the generator motor 4 is electrically driven. Acts (step 110). As a result, an output EM (= LR−Lc) corresponding to the rotational speed difference ΔH is generated from the generator motor 4, and the output of the engine 2 is assisted.
[0232]
As described above, according to the thirteenth control, it is possible to compensate for a shortage of engine output with respect to a rapidly increasing load while reducing fuel consumption when the load suddenly increases.
[0233]
・ 14th control
Next, an embodiment capable of securing the remaining amount of the battery 10 will be described.
[0234]
As described in the tenth control, when the engine 2 is controlled so that the engine output LD matches the actuator-side required output, that is, the following equation (14):

Alternatively, the following formula (24):
Engine output L D = Actuator side required output (Oil load LR) (24)
Is established, there is a possibility that the engine 2 does not have enough horsepower to generate power by the generator motor 4, and the remaining amount E (power storage amount) of the battery 10 may be insufficient.
[0235]
The control of this embodiment will be described using steps 111, 112, 113, 101, 102, 103, 104, and 106 in FIG.
[0236]
First, the detected value E of the voltage sensor 16 is taken into the controller 7 as the current remaining amount E of the battery 10 (step 111), and the remaining amount deviation ΔEG between the target remaining amount Ep of the battery 10 and the current remaining amount E is calculated (step 111). Step 112).
[0237]
Here, the residual deviation ΔEG is obtained using a delay filter. For example, an average value of the remaining amount E for the past two seconds is obtained, and a deviation between the target remaining amount Ep and this average value is set as a remaining amount deviation ΔEG. This is because the battery remaining amount E largely fluctuates in a short time, so that the fluctuation is absorbed by the delay filter to obtain a stable value. Further, as shown in FIG. 23, a dead zone having a predetermined width ΔE (± 1 / 2ΔEp with respect to Ep) may be provided in the target remaining amount Ep. If the current remaining amount E is within the target remaining amount range Ep ± 1 / 2ΔEp, the remaining amount deviation ΔEG is regarded as 0 (step 114).
[0238]
Next, the equation (14) is changed to the following equation (14) ′ so that the engine output LD becomes a value obtained by adding the output ΔEG corresponding to the remaining amount deviation to the actuator side required output (Le + LR in the equation (14)). Is modified like the formula

The expression (14) ′ includes the oil machine load LR calculated at step 101, the turning generator motor output Le, and the output ΔEG corresponding to the remaining amount deviation obtained at step 112.
Is substituted to determine the engine output LD (step 102).
[0239]
Thereafter, similarly to the tenth control, the controller 7 outputs the rotation command value N0 to the governor 3 to control the engine 2 so that the engine output LD obtained in step 102 can be obtained (steps 103, 104, 106). .
[0240]
When the upper swing body W2 is actuated by a hydraulic actuator, the above equation (24) is changed from the engine output LD to the actuator side required output (LR in the above equation (24)). The following equation (24) ′ modified to be a value obtained by adding the output ΔEG of
Engine output LD = oil machine load LR + battery remaining amount deviation ΔEG (24) ′
Is used to obtain the engine output LD, and the engine 2 may be controlled so that the engine output LD is obtained.
[0241]
As a result, an engine output having a margin corresponding to the remaining amount deviation ΔEG of the battery 10 with respect to the load is generated. The output corresponding to the remaining amount deviation ΔEG is absorbed by the generator motor 4, and the electric power corresponding to the remaining amount difference ΔEG is accumulated in the battery 10 via the inverter 8. Therefore, the remaining amount of the battery 10 is always maintained near the target remaining amount Ep or the target remaining amount range Ep ± 1 / 2ΔEp in FIG.
[0242]
For this reason, when the oil machine load LR and the turning load Le increase and exceed the actual engine output Lc, electric power is reliably supplied from the battery 10 to the generator motor 4, and the generator motor 4 is electrically operated and the generator motor 4 It is guaranteed that the output of the engine 2 is assisted by the output EM.
[0243]
As described above, according to the fourteenth control, the remaining amount of the battery 10 can be constantly maintained at a certain level or higher, so that the engine output can be reliably assisted by the generator motor 4 when the load increases.
[0244]
The fourteenth control can be implemented in combination with the eleventh control, the twelfth control, and the thirteenth control as appropriate.
[0245]
In the above description, the actuator-side required output is calculated, but implementation without calculating the actuator-side required output is also possible.
[0246]
In this case, a torque command for generating an output corresponding to the calculation remaining amount deviation ΔEG is given from the controller 7 to the inverter 8. For this reason, the load applied to the engine 2 by the generator motor 4 is in accordance with the battery remaining amount deviation ΔEG. In the engine 2, the output of the engine 2 and the load are balanced and matched on the target torque line L1 in the same manner as described with reference to FIG. That is, the engine output LD is matched to the load obtained by adding the actuator-side required output (turning motor load Le + oil machine load LR) and the load of the generator motor 4 (battery remaining amount deviation ΔEG) on the balance target torque line L1. become.
[0247]
Specific control contents will be described with reference to FIG.
[0248]
・ When the upper limit line U is exceeded
As already described with reference to FIG. 22, when the actual engine speed Nnr is lower than the upper limit speed Nnm, the injection amount α (Nnd−Nnr) is the maximum injection amount α (Nnd defined by the upper limit line U. -Nnm) is exceeded and the inverter 8 is positive so that a torque α (Nnm-Nnr) corresponding to the difference Nnm-Nnr between the upper limit rotational speed Nnm and the actual rotational speed Nnr is generated in the generator motor 4 A torque command is given. That is, regardless of the value of the battery remaining amount deviation ΔEG, a positive torque command for generating the insufficient torque α (Nnm−Nnr) is given from the controller 7 to the inverter 8. For this reason, the generator motor 4 is electrically operated to assist the engine output.
[0249]
However, when the calculation remaining amount deviation ΔEG is negative, the current remaining amount E is large with respect to the target remaining amount Ep and there is a margin in the amount of power stored in the battery 10, so that the remaining torque α (Nnm−Nnr) A positive torque command for generating an output obtained by adding the amount deviation ΔEG may be given to the inverter 8 to increase the assist amount of the generator motor 4.
[0250]
・ When upper limit line U is not exceeded
When the actual engine speed Nnr is equal to or higher than the upper limit speed Nnm, it is determined that the injection amount α (Nnd−Nnr) is less than or equal to the maximum injection amount α (Nnd−Nnm) defined by the upper limit line U. A torque command for generating positive and negative outputs corresponding to ΔEG is given to the inverter 8. Therefore, when the calculated remaining amount deviation ΔEG is positive, a negative torque command for absorbing torque corresponding to the calculated remaining amount difference ΔEG is given to the inverter 8, and the generator motor 4 causes the calculated remaining amount difference ΔEG to be equivalent. Is absorbed and the generator motor 4 generates power.
[0251]
When the calculated remaining amount deviation ΔEG is negative, a positive torque command for generating a torque corresponding to the calculated remaining amount difference ΔEG is given to the inverter 8, and the generator motor 4 is electrically operated. Torque corresponding to the calculation remaining amount deviation ΔEG is generated.
[0252]
・ 15th control
Next, an embodiment in which an emergency measure can be taken when the remaining amount of the battery 10 falls below the lower limit will be described.
[0253]
As in the case of the eleventh control, the engine 2 in this embodiment is a small engine 2 that operates at a rated point V1 having a lower engine output than the rated point V2 of the conventional engine as shown in FIG. used.
[0254]
As shown in FIG. 4, the rated point V1 of the engine 2 of the present embodiment exists in a region where the fuel consumption is smaller (good) on the isofuel curve M than the rated point V2 of the conventional engine.
[0255]
The control of this embodiment will be described using steps 111, 112, 113, 114, 101, 102, 103, 104, and 106 in FIG.
[0256]
That is, in the same manner as in the eleventh control, the remaining amount deviation ΔEG between the target remaining amount Ep of the battery 10 and the current remaining amount E is calculated (steps 111, 112, 113). Next, it is determined whether or not the remaining amount deviation ΔEG is larger than the remaining amount deviation threshold value ΔE0. That is, it is determined whether or not the current remaining amount E of the battery 10 is below the lower limit value E0 (step 114). As a result, when it is determined that the remaining battery level E is equal to or greater than the lower limit value E0 (determination NO in step 114), the process proceeds to step 102, and the same control as the eleventh control is performed thereafter. At this time, as shown in FIG. 4, the engine 2 is controlled with the rated point as V1 and the upper limit value of the engine output as the first upper limit value LM, as described in the eleventh control (step). 103, 104, 106). As a result, the engine 2 normally operates at the rated point V1 where the engine output is smaller than the conventional engine (rated point V2) but the fuel efficiency is good.
[0257]
However, if the engine 2 is always operating at the rated point V1 where the engine output tends to be insufficient, the electric power accumulation in the battery 10 tends to be insufficient, and the remaining battery level E falls below the lower limit E0. There is a risk that power will not be supplied to the device.
[0258]
Therefore, if it is determined that the remaining battery level E is below the lower limit value E0 (YES in step 114), the second upper limit value where the upper limit value of the output of the engine 2 is greater than the first upper limit value LM. The target torque line L1 is corrected so that the value L'M is obtained, and the engine output line G is also rewritten. That is, as shown in FIG. 4, the rated speed NR is increased to a higher rated speed N'R, and the rated point V1 is shifted to the rated point V'1 at which a higher engine output L'M can be obtained (see FIG. 4). 4, step 115), a line segment connecting the rated point V'1, the minimum fuel consumption point M1, and the decel point N1 is set as a new target torque line, and an engine output line corresponding to the target torque line is newly obtained. (Steps 103 and 104).
[0259]
As a result, the engine 2 is operated at the rated point V'1 at which a high engine output L'M is obtained, although the fuel efficiency is deteriorated (step 106). As a result, the increased engine output is absorbed by the generator motor 4, and the electric power generated by the generator motor 4 is accumulated in the battery 10 via the inverter 8.
[0260]
As described above, according to the fifteenth control, when the engine 2 is normally operated at the rated point V1 with good fuel efficiency, but the remaining amount of the battery 10 falls below the lower limit, the rated point V1 is set to the rated point V1. Although the fuel efficiency deteriorates by shifting to '1', the emergency measure to increase the engine output is taken so that the battery 10 can accumulate electric power and avoid the situation where the electric power supplied from the battery 10 to the generator motor 4 is insufficient. can do.
[0261]
The fifteenth control can be implemented in combination with the twelfth control and thirteenth control described above as appropriate.
[0262]
Further, the above-described control for increasing the upper limit value of the output of the engine 2 in the short term may be performed manually. That is, when the operator feels that the engine output is insufficient during work, the operator turns on the switch 42 provided on the knob of the operation lever 41a. When an ON signal ON indicating that the switch 42 is turned on is input to the controller 7, the controller 7 performs a process of correcting the target torque line and the engine output line as described above (step of FIG. 3). 115, 103, 104), the output upper limit value of engine 2 is shifted from LM to L'M, and engine 2 is operated at rated point V'1 at which a higher engine output is obtained (step 106).
[0263]
If it is determined that the remaining battery level E is lower than the lower limit E0 (YES in step 114), a display command is output from the controller 7 to the monitor panel 50 to notify the operator or the like to that effect. Then, a warning message indicating that “the battery 10 is insufficient” is displayed on the display screen 50a of the monitor panel 50.
[0264]
・ 16th control
In the fifteenth control described above, emergency measures are taken to raise the upper limit value of the engine 2 in the short term when the remaining battery level E is below the lower limit value E0. Instead of handling by increasing the upper limit value, it may be handled by limiting the output of the actuator of the construction machine 1.
[0265]
For example, when it is determined that the remaining battery level E is below the lower limit E0, it is conceivable to limit the maximum tilt angle of the swash plate 6a of the hydraulic pump 6 to limit the pump absorption horsepower. As shown in FIG. 24, it is conceivable to limit the pump absorption horsepower by setting the PQ curve LN1 of the hydraulic pump 6 to a PQ curve LN2 that provides a lower absorption horsepower. Further, when it is determined that the remaining battery level E is lower than the lower limit value E0, it is conceivable to limit the output upper limit value of the turning electric motor 11 to a low value.
[0266]
As a result, the oil machine load LR and the turning load Le are reduced, and a margin for generating the generator motor 4 in the output of the engine 2 is generated by the reduction, and the engine output absorbed by the generator motor 4 is stored in the battery 10 as electric power. be able to.
[0267]
・ 17th control
FIG. 11 is a graph showing the state of the output Lc of the engine 2 of the construction machine 1, the oil machine load (pump absorption horsepower) LR, and the output CD of the battery (capacitor) 10. The horizontal axis indicates time and the vertical axis indicates the output (kW ). FIG. 11 shows a case where the control content shown in FIG. 3 is implemented.
[0268]
In FIG. 11, the characteristic of the engine output Lc is indicated by K1, the characteristic of the oil machine load LR is indicated by K2, and the characteristic of the battery output CD is indicated by K3.
[0269]
In B2 shown in FIG. 11, the heavy load excavation work is performed by operating the boom operation lever 41a to the maximum operation amount, and the oil machine load K2 exceeds the engine output K1. At this time, the battery 10 is discharged, the generator motor 4 is electrically operated, and the engine output which is insufficient with respect to the oil machine load K2 is assisted by the output of the generator motor 4.
[0270]
In B3 shown in FIG. 11, the boom operation lever 41a is returned to perform a relatively light load operation, and the engine output K1 exceeds the oil machine load K2. At this time, the generator motor 4 is generating power, and the battery 10 is charged with power corresponding to the remaining amount deviation ΔEG. When the engine output K1 greatly exceeds the oil machine load K2, the amount of charge to the battery 10 increases as indicated by B5.
In B4 shown in FIG. 11, the turning operation lever is operated to perform turning work, and the engine output K1 exceeds the oil machine load K2. At this time, the generator motor 4 is generating power, electric power is supplied from the generator motor 4 to the turning generator motor 11, and the turning generator motor 11 is operating.
[0271]
As shown in B1 of FIG. 11, when excavation work is started, the operation lever 41a is operated from the neutral position and the oil machine load K2 rises, but the engine output K1 rises with a delay from the oil machine load K2. As shown in FIG. 3, an oil machine load LR is calculated (step 101), an engine output LD corresponding to the oil machine load LR is obtained (step 102), and a target rotational speed ND corresponding to the engine output LD is obtained. (Step 104), and the governor 3 operates so as to obtain the target rotational speed ND (Steps 105 and 106), the output of the engine 2 actually increases to the calculated engine output LD. This is because when there is a time delay and the output of the engine 2 actually increases, the actual oil machine load has already increased above the calculated oil machine load LR.
[0272]
The difference between the oil machine load K2 and the engine output K1 when the operation lever is turned on is that of the generator motor 4 as shown in the above equation (11) (generator motor output EM = oil machine load LR−actual engine output Lc). Compensated by output EM. That is, the battery 10 is discharged and the generator motor 4 is electrically operated to generate the generator motor output EM. The generator motor output EM causes the actual oil machine load K2 and the actual engine output K1 indicated by B1 in FIG. The difference is assisted.
[0273]
For this reason, it is necessary to design the generator motor 4 so as to obtain a maximum output corresponding to the difference between the oil machine load K2 and the engine output K1 when the operation lever is turned on.
[0274]
Therefore, if the difference between the oil machine load K2 and the engine output K1 when the operation lever is turned on can be reduced, the maximum output of the generator motor 4 can be reduced, and the generator motor 4 can be downsized accordingly.
[0275]
Hereinafter, an embodiment in which the generator motor 4 can be miniaturized will be described.
[0276]
FIG. 12 shows the operating characteristic C of the operating lever 41a. The horizontal axis represents the lever operating amount S, and the vertical axis represents the speed of the work machine (boom). The same applies to arms and buckets other than the boom.
[0277]
When the operation lever 41a is operated from the neutral position, the swash plate 6a of the hydraulic pump 6 rises from the minimum tilt angle (the capacity D rises), and the pump absorption horsepower rises. The operator predicts an increase in the oil machine load and operates the operation lever 41a at a speed according to the load increase. For this reason, the increment of the oil machine load LR can be predicted from the speed at which the operation lever 41a is operated.
[0278]
The controller 7 takes in a signal indicating the operation amount S of the operation lever 41a from the operation sensor 41b, measures the time τ to reach the threshold value Sc from the neutral position as shown in FIG. An operation amount ΔS / τ is calculated.
[0279]
Next, from the lever operation amount ΔS / τ per unit time, a rotation speed increment ΔN (load increment predicted value) to be added to the rotation command value N0 is calculated.
[0280]
When the oil machine load LR is calculated in step 101 in FIG. 3 and the target rotational speed ND is obtained from the oil machine load LR (step 104), the rotational speed increment (load increment predicted value) is added to the target rotational speed ND. ) A rotation command value ND + ΔN (N0 + ΔN) obtained by adding ΔN is generated (step 105), and this rotation command value ND + ΔN (N0 + ΔN) is output to the governor 3.
[0281]
As a result, the engine output rapidly increases as the operation lever is turned on, and the difference between the oil machine load K2 and the engine output K1 when the operation lever is turned on becomes small. Therefore, the maximum output EM that can be output by the generator motor 4 can be reduced, and the generator motor 4 can be reduced in size accordingly.
[0282]
It should be noted that the control of the embodiment is desirably performed when the load increases rapidly, such as when the operation lever is turned on. For this reason, when a threshold value is set for the rotational speed increment (predicted load increment value) ΔN and the rotational speed increment (predicted load increment value) ΔN exceeds a threshold value (for example, an increase corresponding to 20 kw / sec in engine output). The control of this embodiment is performed.
[0283]
Further, instead of the lever operation amount ΔS / τ per unit time, a rotation speed increment ΔN (load increment predicted value) to be added to the rotation command value may be calculated from the lever operation amount ΔS.
[0284]
FIG. 15 is a diagram for explaining the control contents of the auto-decel. The horizontal axis represents the time change (seconds) of the state of the operation lever, and the vertical axis represents the engine speed N. The auto-decel control is executed when the engine speed N is equal to or higher than the decel speed N1 (1400 rpm). FIG. 15 is based on the case where the fuel dial 17 is set to the rated speed NR.
[0285]
That is, as shown in FIG. 15, when all the operating levers are returned to the neutral position, the engine speed N is about 100 rpm lower than the rated speed NR set by the fuel dial 17 at Δt1 seconds. Decreases to rotation speed. When Δt2 seconds elapses, the engine speed N decreases to a second deceleration speed N1 (hereinafter simply referred to as “decel speed; 1400 rpm”) lower than the first deceleration speed in Δt3 seconds, and one of the operation levers is operated. Until that, the deceleration speed N1 is maintained.
[0286]
If any of the operating levers is operated from the neutral position while the engine speed N is maintained at the deceleration speed N1, the engine speed N is set by the fuel dial 17 at Δt0 (for example, 1 second). It rises to the rated rotational speed NR.
[0287]
The deceleration speed N1 of 1400 rpm is set as a middle speed between the low idle speed NL of 1000 rpm and the high idle speed NH of 2200 rpm. The reason for this is to ensure the responsiveness of the engine 2 when the operation lever is operated from the neutral position. When designing a construction machine, it is within a predetermined time Δt0 (for example, 1 second) until the rated speed NR is reached from the no-load state when the operating lever is operated from the neutral position and the oil machine load is applied. Required for quality assurance. If the deceleration speed N1 is set low, the above request cannot be met. Therefore, the deceleration speed N1 is set to a medium speed higher than the low idle speed NL, and the engine 2 at the start of the operation lever operation is high. Responsiveness is ensured.
[0288]
However, from the viewpoint of reducing fuel consumption, it is not necessarily appropriate to set the deceleration speed N1 to the medium speed speed (1400 rpm).
[0289]
FIG. 16 illustrates data obtained by measuring fuel consumption when loading and excavation work is performed with a construction machine for a predetermined cycle time. The horizontal axis in FIG. 16 indicates time (sec), and the vertical axis indicates fuel consumption (kg / h) per unit time.
[0290]
As shown in FIG. 16, the fuel consumption of the excavating and loading work machine is represented by an area FL1 obtained by integrating the time on the horizontal axis and the fuel consumption rate on the horizontal axis. The fuel consumption when the rotational speed N1 is maintained is represented by the area FL2 integrated in the same manner. The total fuel consumed during work is the sum of FL1 and FL2. The ratio FL2 / (FL1 + FL2) of the consumed fuel FL2 at the time of decelerating to the total consumed fuel FL1 + FL2 reaches 5 to 10% due to the accompanying torque of the hydraulic pump. The above is about fuel consumption, but the same applies to noise.
[0291]
Below, while reducing fuel consumption and noise when the operating lever is returned to the neutral position, the engine speed is reduced to the target speed (rated for 1 second) when the operating lever is operated from the neutral position. An embodiment which can be increased to the rotational speed NR) will be described.
[0292]
・ 18th control
First, the operator selects either “fuel economy priority mode” or “responsiveness priority mode” by selecting one of the selection switches 51 and 52 on the monitor panel 50 shown in FIG. The selection switch 51 is a selection switch for setting the deceleration speed N'1 to a speed (for example, 700 rpm) lower than the low idle speed NL, and the selection switch 52 selects the deceleration speed N'1 with the selection switch 51. This is a selection switch for setting the rotational speed higher than the rotational speed to be set.
[0293]
When one of the selection switches 51 and 52 is selected, a signal indicating the selected content is input to the controller 7.
[0294]
On the other hand, the controller 7 receives operation signals from the operation sensors including the operation sensor 41b of the boom operation lever 41a.
[0295]
Based on the operation signal, the controller 7 determines whether all the operation levers have been returned to the neutral position. As a result, if it is determined that all the operation levers have been returned to the neutral position, the engine speed N is set to the deceleration speed N′1 (selected by the selection switches 51 and 52) in the same manner as in FIG. For example, the rotation command value is output to the governor 3 so as to decrease the speed to 700 rpm), and the deceleration speed N′1 is maintained until any one of the operation levers is operated. For this reason, the fuel consumption at the time of neutral of the control lever is improved as compared with the conventional case.
[0296]
If it is determined that any of the operating levers has been operated from the neutral position while the engine speed N is maintained at the deceleration speed N′1, the controller 7 controls the governor 3 with respect to the engine speed. A rotation command value is output so as to increase N to the engine speed ND corresponding to the current load (to the rated speed NR set by the fuel dial 17), and a positive (+) polarity is output to the inverter 8. A torque command value TD is output and the generator motor 4 is operated as a motor.
[0297]
Therefore, the output of the generator motor 4 is added to the output of the engine 2 when the matching point moves from the no-load decel point N′1 to the high-load rated point V1. Since the engine output is assisted by the output of the generator motor 4, it moves to the rated point V1 with good responsiveness in a short time (for example, about 1 second) as in the prior art.
[0298]
The effect of the present embodiment will be described with reference to FIG.
[0299]
FIG. 13 shows the maximum torque line R3 (1 hour rating) and R'3 (1 minute) of the present embodiment in which the maximum torque line of the generator motor 4 is added to the maximum torque line R2 of the conventional engine and the maximum torque line R1 of the engine 2. (Rated) is shown in comparison.
[0300]
The time for accelerating the engine when the operation lever is operated is defined by the area indicated by hatching obtained by subtracting the oil machine load γ from the maximum torque line as shown in FIG. The larger the area obtained by subtracting the oil machine load γ from the maximum torque line, the greater the margin of torque for accelerating the engine, and the target rotational speed NR can be reached in a shorter time.
[0301]
The area obtained by subtracting the oil machine load γ from the conventional maximum torque line R2 is ε1, whereas the area obtained by subtracting the oil machine load γ from the maximum torque line R′3 (rated for 1 minute) of this embodiment is ε1. The area is the sum of ε3, and the torque margin for accelerating the engine 2 is larger than that of the conventional engine. Similarly, the area obtained by subtracting the oil machine load γ from the maximum torque line R3 (1 hour rating) of this embodiment is the area obtained by adding ε2 to ε1, and the torque margin for accelerating the engine 2 is larger than that of the conventional engine.
[0302]
In addition, since the generator motor 4 generates a large torque at a low speed as compared with the engine 2, a large torque margin is generated at the start of the engine rotation.
[0303]
For this reason, even if the deceleration speed N'1 is set to a very low speed N1 '(for example, 700 rpm) lower than the conventional deceleration speed N1 (1400 rpm) and further lower than the idle speed NL, this embodiment is implemented. In the case of the example, when the operation lever 41a is operated from the neutral position, the engine speed N quickly rises as shown by the acceleration torque locus α, and the rated point V1 in a short time (for example, 1 second or less) as before. To reach.
[0304]
As described above, according to this embodiment, the deceleration speed when the operation lever is neutral is set to the extremely low speed N1 ′ (for example, 700 rpm), and the generator motor 4 generates acceleration of the engine 2 when the operation lever is operated. Thus, the engine 2 is operated for a short time (for example, when the operation lever is operated from the neutral position while reducing the fuel consumption and noise when the operation lever is returned to the neutral position. 1 second), the target rotational speed (rated rotational speed NR) can be increased.
[0305]
However, when the lower deceleration speed N′1 is set by the selection switch 51, the fuel efficiency is improved, but the response of the engine 2 is relatively deteriorated, and the higher deceleration speed N′1 is increased by the selection switch 52. When set, the responsiveness of the engine 2 is improved, but the fuel consumption is relatively deteriorated.
[0306]
Although the selection speed 51 'is changed in two steps by the selection switches 51 and 52, the deceleration speed N'1 may be continuously changed by a dial or the like.
[0307]
Further, since it may not be desirable to set the deceleration speed N′1 low depending on conditions such as weather conditions and engine warm-up conditions, the deceleration speed N′1 may be changed to be higher depending on the conditions.
[0308]
For example, when the coolant temperature of the engine 2 is detected and the coolant temperature is not more than a specified value (for example, 70 ° C.), the deceleration speed N ′ 1 is set to a higher speed. Further, when the remaining amount of the battery 10 is detected and the remaining amount of the battery is below a specified value (for example, SOC 20%), the deceleration speed N′1 is set to a higher speed. When the atmospheric pressure is detected and the atmospheric pressure is not more than a specified value (for example, 700 mmHg), the deceleration rotation speed N′1 is set to a higher rotation speed. Further, the temperature of the air sucked into the engine 2 is detected, and when the intake air temperature is equal to or higher than a specified value (for example, 45 ° C.), the deceleration speed N′1 is set to a higher speed.
[0309]
・ 19th control
In the eighteenth control described above, the engine 2 is rotated when the operation lever is neutral, but the engine 2 may be stopped.
[0310]
In this case, the operator selects the “stop control mode” by selecting the selection switch 53 on the monitor panel 50 shown in FIG.
[0311]
When the selection switch 53 is selected, a signal indicating that stop control should be executed is input to the controller 7. However, it is desirable that the selection operation of the selection switch 53 is effective only for one stop control. That is, after the stop control is performed once, it is desirable not to execute the next stop control unless the selection switch 54 is selected again. Here, the “stop control” means that the engine 2 is stopped when all the operation levers are returned to the neutral position, and the engine 2 is started when any of the operation levers is operated from the neutral position, so that the load is applied. It is a series of control contents to increase to the corresponding rotation speed.
[0312]
On the other hand, the controller 7 receives operation signals from the operation sensors including the operation sensor 41b of the boom operation lever 41a.
[0313]
Based on the operation signal, the controller 7 determines whether all the operation levers have been returned to the neutral position. As a result, when it is determined that all the operating levers have been returned to the neutral position, a command is output to the governor 3 to stop the engine 2, that is, to stop the fuel supply, and any one of the operating levers operates. Keep the engine stopped until For this reason, the fuel consumption in the neutral state of the control lever is greatly improved as compared with the conventional case.
[0314]
When it is determined that one of the operation levers has been operated from the neutral position while the engine 2 is stopped, the controller 7 sets the engine speed N to the governor 3 according to the current load. A rotation command value is output so as to increase to the rotation speed ND (to the rated rotation speed NR set by the fuel dial 17), and a positive (+) polarity torque command value TD is output to the inverter 8 to generate a generator motor. 4 is operated as an electric motor.
[0315]
For this reason, the engine 2 is started by the rotation of the generator motor 4, and the engine output is assisted by the output generated by the generator motor 4, and the response to the rated point V1 in a short time (for example, about 1 second) as before. Move well.
[0316]
Here, as shown in FIG. 13 (b), the generator motor 4 generates a large torque from the start of the generator motor 4 (at the start of the engine 2) compared to the engine 2, so that a large torque at the start of the engine rotation. There is room.
[0317]
Therefore, even if the engine 2 is stopped, when the operation lever 41a is operated from the neutral position, the engine speed N quickly rises and reaches the rated point V1 in a short time (for example, 1 second or less) as in the prior art. Can be secured.
[0318]
Thus, according to the present embodiment, the engine 2 is stopped when the operation lever is neutral, and the engine 2 is started by rotating the generator 2 when the operation lever is operated, and the acceleration of the engine 2 is assisted by the torque generated by the generator motor 4. Since the fuel consumption and noise when the operation lever is returned to the neutral position are reduced as compared with the conventional case, the engine 2 is operated in a short time (for example, 1 second) when the operation lever is operated from the neutral position. The target rotational speed (rated rotational speed NR) can be increased.
[0319]
Further, since the generator motor 4 also functions as a starter for starting the engine, it is not necessary to provide a separate starter, and the number of parts and cost can be reduced. Further, if the generator motor 4 is configured by modifying an existing starter so that the output of the engine 2 can be assisted, the system of the present embodiment can be configured without any significant modification to the existing device.
[0320]
By the way, when the stop control is executed, the engine 2 is automatically stopped and the engine 2 is automatically started. Therefore, it is necessary to alert the operator and surrounding people.
[0321]
When the stop control is started, an alarm command is output from the controller 7 to the buzzer 19 and the buzzer 19 sounds. This alerts the operator and the people around the construction machine 1 that “stop control is being executed; it is dangerous because the work machine moves when the operation lever is operated”. A melody or voice may be generated by a speaker or the like. Further, a display command is output from the controller 7 to the monitor panel 50, and a display indicating that “stop control is being executed” is similarly performed on the display screen 50a of the monitor panel 50. Moreover, you may make it perform the same display on the indicator provided in the exterior of the construction machine 1. FIG. For the display, the pilot lamp may be simply turned on or blinked, or characters, symbols, pictures, etc. may be turned on or blinked.
[0322]
Further, an alarm may be generated by sound or display until the stop control is ended after the selection switch 53 is selected, and the alarm is generated by sound or display only when the engine 2 is stopped and waiting. It may be generated.
[0323]
Further, since it may not be desirable to stop the engine 2 depending on conditions such as weather conditions and engine warm-up conditions, the engine 2 may not be stopped depending on the conditions.
[0324]
For example, when the engine coolant temperature is less than a specified value (for example, 70 ° C.), when the remaining battery capacity is less than the specified value (for example, SOC 20%), when the atmospheric pressure is less than the specified value (for example, 700 mmHg), Is equal to or higher than a specified value (for example, 45 ° C.), the engine 2 is not stopped even if all the operation levers are returned to the neutral position, and instead, the sixteenth control described above is executed, The rotational speed is reduced to the deceleration rotational speed N'1.
[0325]
-20th control
Next, a modification of the nineteenth control described above will be described.
[0326]
The apparatus of this embodiment includes an LS valve 14 as shown in FIG. The LS valve 14 operates so that the differential pressure ΔP between the discharge pressure P of the hydraulic pump 6 and the load pressure PLS of the hydraulic cylinder 31 becomes a constant differential pressure ΔPLS.
[0327]
When the opening area of the spool of the operation valve 21 is A and the resistance coefficient is c, the discharge flow rate Q of the hydraulic pump 6 is expressed by the above-described equation (2) (Q = C · A · √ (ΔP)).
[0328]
Since the differential pressure ΔP is made constant by the LS valve 14, the pump flow rate Q changes only depending on the opening area A of the spool of the operation valve 21.
[0329]
When the operating lever for work implement 41a is operated from the neutral position, the opening area A of the spool of the operation valve 21 increases according to the operation amount, and the pump flow rate Q increases as the opening area A increases. At this time, the pump flow rate Q is not affected by the size of the oil machine load and is determined only by the operation amount of the work machine operation lever 41a. By providing the LS valve 14 as described above, the pump flow rate Q does not increase / decrease depending on the load and changes according to the operator's intention (according to the operation position of the operation lever). improves.
[0330]
Between the discharge flow rate Q of the hydraulic pump 6, the rotational speed N of the engine 2, and the capacity D of the hydraulic pump 6, the above-described relationship (1) (Q = N · D) is established.
[0331]
Here, it is assumed that the tilt angle of the swash plate 6a of the hydraulic pump 6 is not limited and the maximum capacity can be obtained at the maximum tilt angle.
[0332]
When the work implement operating lever 41a is operated, the spool opening area A increases from the above equation (2), and the hydraulic pump 6 tries to discharge a large flow rate Q corresponding to the increased opening area A. However, when the operation lever 41a for the work implement is started, the engine is stopped, and from the above equation (1) (Q = N · D), even when the engine speed rises, the rotational speed is almost zero, which is almost zero. Regardless, the pump capacity D is maintained at the maximum capacity in order to discharge the required large flow rate Q.
[0333]
Although the acceleration of the engine 2 is assisted by the torque generated by the generator motor 4 when the operation lever is operated, the hydraulic pump 6 is maintained at the maximum capacity and the hydraulic oil having a large flow rate Q corresponding to the operation amount of the operation lever 41a is discharged. Therefore, the torque of the engine 2 does not have a margin for the acceleration of the engine 2 and is absorbed by the hydraulic pump 6, and the acceleration performance at the start of engine rotation deteriorates.
[0334]
Therefore, in the twentieth control, when the work implement operating lever 41a is operated from the neutral position, the capacity of the hydraulic pump 6 is increased until a predetermined time is reached or until the engine speed reaches the predetermined speed. Limit the value to less than the maximum capacity. Specifically, the tilt angle of the swash plate 6a of the hydraulic pump 6 is limited to a tilt angle smaller than the maximum tilt angle.
[0335]
As a result, the flow rate Q required by the hydraulic pump 6 is limited, and a margin is generated in the torque of the engine 2, and the torque margin is used for accelerating the engine 2 and the acceleration performance at the start of engine rotation is improved.
[0336]
As described above, according to the twentieth control, it is possible to improve the acceleration of the engine when the operation lever is turned on from the engine stop state while improving the fine controllability of the operation lever.
[0337]
The eighteenth control, the nineteenth control, and the twentieth control can be implemented in appropriate combination with the first, second, fourth, and sixth to seventeenth controls described above. That is, the decel point N1 shown in FIG. 4 and the like is changed to a decel point N'1 having a lower rotational speed, a target torque line passing through the decel point, such as the target torque line L1, is set, and various controls are executed. .
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an embodiment.
FIG. 2 is a diagram for explaining signals input to and output from the controller shown in FIG. 1;
FIG. 3 is a diagram showing control contents executed by the controller shown in FIG. 1;
FIG. 4 is a diagram showing a torque diagram of an engine.
FIG. 5 is a diagram showing a torque diagram of an engine.
FIG. 6 is a diagram showing a torque diagram of the engine.
FIG. 7 is a diagram showing a torque diagram of the engine.
FIG. 8 is a diagram showing a torque diagram of the engine.
FIG. 9 is a diagram showing a torque diagram of the engine.
FIG. 10 is a diagram showing a torque diagram of the engine.
FIG. 11 is a diagram for explaining the result of executing the control content of FIG. 3;
FIG. 12 is a diagram illustrating operation characteristics of the operation lever.
FIGS. 13 (a) and 13 (b) are diagrams illustrating a torque diagram and illustrating how the engine is accelerated.
FIG. 14 is a diagram showing a torque diagram of a conventional engine.
FIG. 5 is a diagram for explaining auto-decel.
FIG. 16 is a diagram for explaining a fuel consumption rate during execution of a conventional auto-decel.
FIG. 17 is a diagram showing an engine torque diagram;
FIG. 18 is a diagram showing an engine torque diagram;
FIG. 19 is a view showing a torque diagram of an engine.
FIG. 20 is a diagram showing a torque diagram of an engine.
FIG. 21 is a diagram showing a torque diagram of an engine.
FIG. 22 is a diagram showing a torque diagram of the engine.
FIG. 23 is a diagram illustrating a target remaining amount range of a battery.
FIG. 24 is a diagram showing a PQ curve of the hydraulic pump.
[Explanation of symbols]
2 Engine
4 generator motor
5 Output shaft
6 Hydraulic pump
7 Controller
10 battery
11 Generator motor for turning
14 LS valve
19 Buzzer
41a Operation lever
50a display screen
51, 52, 53 selection switch

Claims (5)

A work machine driven by an engine as a drive source according to the operation of the work machine operator;
An electric motor coupled to the output shaft of the engine;
When the work implement operator is returned to the neutral position, the engine speed is reduced to a set rotational speed, and when the work implement operator is operated from the neutral position, the engine rotation speed is reduced. An engine rotation speed control device for a working machine, comprising: control means for operating the electric motor until the engine rotation speed reaches the target rotation speed so that the number reaches the target rotation speed within a predetermined time. The engine rotation speed control device for a work machine according to claim 1, further comprising selection means for selecting the set rotation speed. A work machine driven by an engine as a drive source according to the operation of the work machine operator;
An electric motor coupled to the output shaft of the engine;
When the work implement operator is returned to the neutral position, the engine is stopped, and when the work implement operator is operated from the neutral position, the engine is started and the engine speed is set for a predetermined time. And a control means for operating the electric motor until the engine speed reaches the target speed so that the target speed is reached . 4. The engine rotation speed control device for a work machine according to claim 3, further comprising alarm output means for outputting an alarm during execution of control by the control means. A hydraulic pump driven by an engine;
A hydraulic actuator operated by pressure oil discharged from the hydraulic pump;
Means for controlling the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the hydraulic actuator to be a constant differential pressure, and
When the work implement operator is operated from a neutral position, the capacity of the hydraulic pump is limited to a value smaller than the maximum capacity until a predetermined time is reached or until the engine speed reaches a predetermined speed. The engine rotation speed control device for a work machine according to claim 3.

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