JP3803812B2

JP3803812B2 - Screw rotor

Info

Publication number: JP3803812B2
Application number: JP27678196A
Authority: JP
Inventors: 徹哉捧; 幸裕小島; 登戸田
Original assignee: HOKUETSU INDUSTRIES CO., LTD.
Current assignee: HOKUETSU INDUSTRIES CO., LTD.
Priority date: 1996-09-12
Filing date: 1996-09-12
Publication date: 2006-08-02
Anticipated expiration: 2016-09-12
Also published as: JPH1089270A

Description

【０００１】
【発明の属する技術分野】
スクリュ流体機械に使用するスクリュロータに関するものであり、特に圧縮機、膨張機、真空ポンプ等に使用するスクリュロータに関するものである。
【０００２】
【従来の技術】
従来、この種のスクリュロータは、ロータ部とロータ軸とが一体的に形成されている。例えば、ロータ部とロータ軸とは同一金属材料から削りだし加工されている。または、金属製のロータ軸の周囲に合成樹脂製のロータを一体成形したものもある。そして、機種間でロータ部の寸法が共通であっても、スクリュ流体機械の吐出圧力や駆動原動機が変わったり、スクリュ流体機械の使用用途に応じて軸長や軸径又は軸部の表面処理が変わるため、ロータの製作工程が複雑となりかつ種類が多い。
このことにより種々の問題があった、スクリュロータ各部の直径を例にとると、一般にロータ歯部の直径は軸部の約３〜４倍となっているのが普通である。そのため製作上次のような問題がある。
（１）ロータ部と軸部とは同一金属材料から削りだし加工されている場合は、ロータ歯部の直径に見合ったサイズの素材を用い、これを所望とする軸部の直径まで切削加工で削りだす必要がある。そのため、材料や加工工数に多大な無駄が生じる。
（２）金属製の軸の周囲に熱硬化性の合成樹脂製のロータを一体成形したものである場合は、軸の直径に見合った金属材料を準備すればよいが、軸径の割に軸長が長いため、加工に際し芯振れ対策等の配慮が必要となり、生産性が悪くなる。
（３）併せて、ロータ軸長が長いため、ロータ部の成形型も大型で高額となる他成形時の作業性も悪い。また、表面処理に際しても同様に作業性が悪い。
（４）例えば、圧縮作用空間に水を噴射して該空間内の冷却と密閉とを行う水噴射式圧縮機等に使用し、軸部が大気もしくは水分を含む流体に触れる場合は、長期使用の間に錆が発生し当該軸封部の漏洩や摺動部の異常摩耗の原因となる。
（５）ロータ部の歯形寸法は共通であるも軸部の直径や軸長が異なるため、部品の共通化ができず製作と管理上も複雑である。
【０００３】
しかして、スクリュ圧縮機ではあるが、重量軽減のために中空小径部と中空大径部とに分割して加工し、各対向端面を摩擦圧接によって接合しよううとするものとして、実開昭５７−１０５４１８号公報があるが、中空軸にしかつその接合も摩擦圧接による接合で上述の種々の課題を解決せんとするものではない。また、単に各クランク軸部をスプラインにより結合し、そのスプライン結合部に弾性体を注入して摩耗を減らし騒音をも低減しようとするものとして、実開昭５６−４９３１１号公報がある。さらに、プロペラシヤフトにおいて、プロペラシヤフトとヨークのいずれか一方に溝を形成し、この溝に係合する突起を他方に形成したものとして、実開平２−７１１０８号公報があり、さらにまた、特公昭５２−２５５６２号公報のように圧縮機の羽根車に一体になったスリーブを設け、このスリーブの穴に螺子が切られ、軸の螺子部が受容されて組立てられるものである、しかし、これらのものは、一般的な取付けをいかに確実にせんとするか等であって、上述の種々の課題を解決せんとするものではない。
【０００４】
【発明が解決しようとする課題】
そこで、第１又は第２に、簡単な軸結合を採用することで、軸長の異なる多機種に同一のロータ部を採用することができ、スクリュロータ材料に無駄があったり、製作加工に多大な工数を要しているためコスト高となっていたのを解消し、さらに、軸を分割でき取扱いが容易で、成形用の機械を小型化し、多機種の内の専用軸の加工のみでよく軸部の加工を容易にして製作コストを引き下げると共に、ロータ軸又は中心軸に凹設した嵌入穴からその反対側の軸端に貫通する通気孔を穿設したことにより、軸結合がスムーズに嵌入されるのでその挿入作業が楽に、確実にできると共に、凹設部の運転中と停止中の温度差による空気の流通（呼吸作用）ができること。
第３に、第１又は第２のいずれかの課題にくわえて、ロータ部とロータ軸との組み立て間違えの防止を図り、より製作コストを低減すること。
第４と第５に、第１乃至第３のいずれかの課題にくわえて、中心軸は合成樹脂により被覆されているため、軸部の防錆対策として、必要な部分だけを容易に防錆処理又は表面処理をできるようにしたり、耐食材料の採用を容易にすること。
第６と第７に、第１乃至第５のいずれかの課題にくわえて、中心軸に外嵌する側の材料の線膨張率が内嵌する軸に比べ小さいため、圧縮作用に伴う伝導熱によって嵌合が締まる方向に作用させ、長期にわたり嵌合状態を確実に保持させること。
【０００５】
【課題を解決するための手段】
本発明は上記課題を解決するために、第１に、スクリュ流体機械のスクリュロータにおいて、スクリュ歯形を形成するロータ部と該ロータ部の軸心上の少なくとも一方の外端に中心軸を延設し、該中心軸の外端に段差を設けて小径軸を突設し、該小径軸に嵌入穴を凹設した別製の軸を外嵌して軸接合すると共に、前記ロータ軸の略軸心には、該ロータ軸に凹設した嵌入穴からその反対側の軸端に貫通する通気孔を穿設したことを特徴とする。第２に、スクリュ流体機械のスクリュロータにおいて、スクリュ歯形を形成するロータ部と該ロータ部の軸心上の少なくとも一方の外端に中心軸を延設し、該中心軸の外端には嵌入穴を凹設し、該嵌入穴に小径軸を突設した別製の軸を内嵌して軸接合すると共に、前記ロータ軸の略軸心には、該中心軸に凹設した嵌入穴からその反対側の軸端に貫通する通気孔を穿設したことを特徴とする。第３に、第１又は第２のいずれかの技術手段に加えて、前記ロータ部の中心軸に突設した小径軸又は凹設した嵌入穴の最始端と最内外端のそれぞれからロータ端面までの長さは該ロータ部を挟んで両軸端共に略同寸法に設定したことを特徴とする。第４に、第１乃至第３のいずれかの技術手段に加えて、前記ロータ部は金属製の中心軸の周囲に熱硬化性の合成樹脂製のロータを一体成形したものであることを特徴とする。第５に、第４の技術手段に加えて、前記ロータ部はその中心軸外周の表面をロータ部と同質の合成樹脂で被覆成形したことを特徴とする。第６に、第１又は第３乃至第５のいずれかの技術手段に加えて、ロータ部の中心軸に外嵌接合するロータ軸の材料は、該中心軸に用いる材料よりも線膨脹係数の小なる性質を有する金属材料であることを特徴とする。第７に、第２乃至第５のいずれかの技術手段に加えて、ロータ部の中心軸に用いる材料は、該中心軸に内嵌接合するロータ軸よりも線膨脹係数の小なる性質を有する金属材料であることを特徴とする。
【０００６】
【実施の形態】
以下、本発明のスクリュ流体機械について説明するが、便宜上スクリュ流体機械を例にして記載する。以下、図１乃至図５の実施例に基づいて説明する。図１と図２に示すように、スクリュ歯形を形成するロータ部１と該ロータ部１の軸心上の少なくとも一方の外端２に中心軸３を延設し、該中心軸３の外端４には段差を設けて小径軸５を突設すると共に、該小径軸５に嵌入穴７を凹設した別製のロータ軸６を外嵌して軸接合した。この場合、好ましくはロータ部１の他端２ａにも上述と同一の中心軸３ａ、小径軸５ａ、別製のロータ軸６ａ、嵌入穴７ａを同様に設けてある。そして、前記ロータ部１の中心軸３、３ａに設けた小径軸５、５ａの最始端２６、２６ａと最外端２７、２７ａのそれぞれからロータ端面であるロータ部の外端２、２ａまでの長さは該ロータ部１を挟んで両軸端共に略同寸法に設定してある。図２はスクリュロータの軸接合前の状態を示す断面図で、図１と同一部位は同一符号を付すことで説明を省略する。
以下本発明ではロータ部とはスクリュ歯形を形成したロータ歯部をも含む。
【０００７】
また、図３に示すように、上述の軸接合を、スクリュ歯形を形成するロータ部１ｃと該ロータ部１ｃの軸心上の少なくとも一方の外端８に中心軸９を延設し、該中心軸９の外端には嵌入穴１０を凹設すると共に、該嵌入穴１０に小径軸１２を突設した別製のロータ軸１１を内嵌した軸接合としてもよい。この場合、好ましくはロータ部１ｃの他端８ａにも上述と同一の中心軸９ａの外端には嵌入穴１０ａを凹設すると共に、別製のロータ軸１１ａに小径軸１２ａを突設し、該小径軸１２ａを前記嵌入穴１０ａに内嵌した軸接合手段が同様にとられている。この場合、好ましくは、前記ロータ部１ｃの中心軸に凹設した嵌入穴１０、１０ａの最始端２８、２８ａと最内端２９、２９ａのそれぞれからロータ端面であるロータ部の外端８、８ａまでの長さは該ロータ部１ｃを挟んで両軸端共に略同寸法に設定してある。
そして、上述の各実施例の軸接合手段としては、穴径を軸径より小さくし、軸を嵌入穴に圧入或いは焼きバメで接合する。また、穴と軸とにスプライン加工を施し軸接合したり、穴と軸とに螺子を切り、螺子係合としてもよい。
【０００８】
さらに、図４に示すように、ロータ部１ｄは金属製の中心軸１３の周囲に熱硬化性の合成樹脂製のロータを一体成形したものである。そして、該ロータ部１ｄの金属製の中心軸１３上の少なくとも一方の外端３２に中心軸１５を延設し、該中心軸１５の外端には嵌入穴１６を凹設すると共に、該嵌入穴１６に小径軸１８を突設した別製のロータ軸１７を内嵌した第３実施例の軸接合とした。この形状を、図５に示すように、ロータ部１ｅの金属製の中心軸１９上の少なくとも一方の外端３５に周囲に合成樹脂を被覆した中心軸２０を延設し、該中心軸２０の外端２１には段差を設けて小径軸２２を突設すると共に、該小径軸２２にはロータ部１ｅとは別製のロータ軸２３の端部に凹設した嵌入穴２４を外嵌して第４実施例の軸接合としてもよい。そして、これらの第３と第４実施例においても、好ましくは各々の他端３２ａ、３５ａにも各図４、図５と全く同じ構造の軸接合手段が施されている、その同一符号にａを付すことで説明を省略する。さらに、この場合も好ましくは、前記ロータ部１ｄの各中心軸に凹設した嵌入穴１６、１６ａの最始端３０、３０ａと最内端３１、３１ａのそれぞれからロータ部の外端３２、３２ａまでの長さ並びに前記ロータ部１ｅの中心軸に設けた小径軸２２、２２ａの最始端３３、３３ａと最外端３４、３４ａのそれぞれからロータ部の外端３５、３５ａまでの長さは各該ロータ部１ｄ、１ｅを挟んで両軸端共にそれぞれ略同寸法に設定してある。さらに、これらの軸接合手段としては、穴径を軸径より小さくし、好ましくは嵌入穴を温め（軸を冷却してもよい）て軸を嵌入穴に圧入するか、上述のように穴と軸とにスプライン加工を施し軸接合したり、穴と軸とに螺子を切り、螺子係合としてもよい。さらにまた、前記ロータ部はその中心軸外周の表面をロータ部と同質の合成樹脂で被覆成形した技術手段をも採用できる。
【０００９】
なお、上述の各第１乃至第４実施例において、軸接合手段としての嵌入穴と小径軸の形状は、円形、三角形、四角形、多角形等でよく、さらに、中心軸の一端に嵌入穴を凹設し、他端に小径軸を突設するように異なる形状としてもよい。また、図４に示すように、ロータ部１ｄの金属製の中心軸１３の延設した周囲は合成樹脂で被覆されていなく、さらに、図５に示すように、ロータ部１ｅの金属製の中心軸１９の延設した周囲には合成樹脂を被覆した中心軸２０としているが、使用条件等によってはロータ部１ｅの金属製の中心軸１９の延設した周囲を合成樹脂を被覆せずに金属製にしたり、或いは、ロータ部１ｄの金属製の中心軸１３の延設した周囲を合成樹脂で被覆してもよい。
【００１０】
さらには、図１乃至図５の各実施例のいずれのものに加えて、前記ロータ軸６、６ａ、１１、１１ａ、１７、１７ａ、２３、２３ａの略軸心には、該ロータ軸又は中心軸に凹設した各嵌入穴７、７ａ、１０、１０ａ、１６、１６ａ、２４、２４ａからその反対側の軸端に貫通する通気孔２５、２５ａ…を穿設した。この場合略軸心とは、各通気孔２５、２５ａ…は各嵌入穴７、７ａ、１０、１０ａ、１６、１６ａ、２４、２４ａのいずれの部位が外気と連通すればよいので本発明では幾何学上の軸心でないので略軸心という（製作上センターの軸心に孔を穿設してもよい）。
【００１１】
さらにまた、ロータ部の中心軸に外嵌接合するロータ軸６、６ａ、２３、２３ａの材料は、該中心軸に用いる材料よりも線膨脹係数の小なる性質を有する金属材料である。又は、ロータ部の中心軸に用いる材料は、該中心軸に内嵌接合するロータ軸１１、１１ａ、１７、１７ａよりも線膨脹係数の小なる性質を有する金属材料である
【００１２】
次ぎに、動作と主な作用について図６の圧縮機に基づいて説明すると、ロータ部と別製のロータ軸とを各実施例の形状及び種々の軸接合手段によって構成されたものは、図６のように外観上は何等変わらず、そのスクリュ流体機械のスクリュロータの機能上も変わらない。そこで、本発明による種々の技術手段の作用について説明する。ロータ部と軸部とを分割構造としたので、ロータ部（ロータ歯部も含む）の寸法の共通化が図れるため、専用の加工機で量産できる一方、軸部は当該軸部同士で単独加工され、それぞれの完成後両者を焼きバメ等により嵌合接合し所望のロータにまとめられる。これにより完成したスクリュロータは加工品質及び性能共に安定したものとなり、大幅な加工工数の低減と製作コストの低減とが可能となる。併せて、部品の共通化により部品管理も容易となる。
また、中心軸は合成樹脂により被覆されているため、軸の防錆効果の他、流体機械の運転中作用室と軸受室との軸封部の僅かな隙間に万一接触があっても焼き付くことがない。
【００１３】
さらに、スクリュロータの中心軸とロータ軸との嵌合時、凹設部に残留する空気はロータ軸に穿設した通気孔から外部に逃げる。よって、凹設部の運転中と停止中の温度差による空気の流通（呼吸作用）ができ接合も確実にできる。
さらにまた、中心軸に外嵌する側の材料の線膨張率が内嵌する軸に比べ小さいため、圧縮作用に伴う伝導熱によって嵌合が締まる方向に作用する。よって長期にわたり嵌合状態を確実に保持できる。そして、長期の運転期間中にロータ歯部又はロータ軸が磨耗したときには、オーバホール時等にそれぞれの該当する部品だけを交換すればよい。
【００１４】
【効果】
第１又は第２に、スクリュロータのロータ部と軸部とを分割構造としたので、ロータ部の寸法が同じであればロータ部については同一の加工段取りで加工できるので、生産性が向上し安定した加工品質を維持でき、かつ部品管理も容易である。また、簡単な軸結合を採用することで、軸長の異なる多機種に同一のロータ部を採用することができ、スクリュロータ材料に無駄をなくし、製作加工に多大な工数を不要としコスト高となっていたのを解消し、さらに、軸を分割でき取扱いが容易で、軸が短くできるため成形用の機械を小型化し、多機種の内の専用軸の加工のみでよく軸部の加工を容易にして製作コストを大幅に引き下げることができた。さらに、軸部については表面処理その他の複雑な製作工程を経る過程でも、部品自体がロータ部に比べて小さいため取扱いも楽で作業性もよい。さらには、ロータ軸又は中心軸に凹設した嵌入穴からその反対側の軸端に貫通する通気孔を穿設したことにより、軸結合がスムーズに嵌入されるのでその挿入作業が楽に、確実にできると共に、凹設部の運転中と停止中の温度差による空気の流通（呼吸作用）ができる。
第３に、第１又は第２のいずれかの効果にくわえて、ロータ部とロータ軸との組み立て間違いの防止ができ、加工部品の共通化を図り、より製作コストを低減することができた。
第４と第５に、第１乃至第３のいずれかの効果にくわえて、中心軸は合成樹脂により被覆されているため、軸部の防錆対策として、必要な部分だけを容易に防錆処理又は表面処理をできるようにしたり、耐食材料の採用が容易である。
第６と第７に、第１乃至第５のいずれかの効果にくわえて、中心軸に外嵌する側の材料の線膨張率が内嵌する軸に比べ小さいため、圧縮作用に伴う伝導熱によって嵌合が締まる方向に作用させ、長期にわたり嵌合状態を確実に保持させれる。
【図面の簡単な説明】
【図１】本発明によるスクリュロータの第１実施例を示す断面図である。
【図２】本発明による第１実施例のスクリュロータの軸接合前の状態を示す断面図である。
【図３】本発明によるスクリュロータの第２実施例を示す断面図である。
【図４】本発明によるスクリュロータの第３実施例を示す断面図である。
【図５】本発明によるスクリュロータの第４実施例を示す断面図である。
【図６】スクリュロータの圧縮機を示す要部概略断面図である。
【符号の説明】
１、１ｂ乃至１ｅロータ部
２、２ａ、８、８ａ、３２、３２ａ、３５、３５ａロータ部の外端
３、３ａ、９、９ａ、１５、１５ａ、２０、２０ａ中心軸
４、４ａ、２１、２１ａ中心軸の外端
５、５ａ、１２、１２ａ、１８、１８ａ、２２、２２ａ小径部
６、６ａ、１１、１１ａ、１７、１７ａ、２３、２３ａロータ軸
７、７ａ、１０、１０ａ、１６、１６ａ、２４、２４ａ嵌入部
１３、１９金属製の中心軸
２５、２５ａ通気孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw rotor used for a screw fluid machine, and more particularly to a screw rotor used for a compressor, an expander, a vacuum pump and the like.
[0002]
[Prior art]
Conventionally, in this type of screw rotor, a rotor portion and a rotor shaft are integrally formed. For example, the rotor portion and the rotor shaft are machined from the same metal material. Alternatively, a synthetic resin rotor may be integrally formed around a metal rotor shaft. And even if the dimensions of the rotor part are common among the models, the discharge pressure and drive motor of the screw fluid machine change, or the shaft length, shaft diameter, or surface treatment of the shaft part depends on the usage application of the screw fluid machine. Because it changes, the manufacturing process of the rotor becomes complicated and there are many types.
Taking the diameter of each part of the screw rotor, which has various problems due to this, for example, the diameter of the rotor tooth part is generally about 3 to 4 times that of the shaft part. Therefore, there are the following problems in production.
(1) If the rotor and shaft are machined from the same metal material, use a material with a size that matches the diameter of the rotor tooth, and cut it to the desired shaft diameter. It is necessary to sharpen. Therefore, a great deal of waste is generated in materials and processing man-hours.
(2) When a thermosetting synthetic resin rotor is integrally formed around a metal shaft, a metal material corresponding to the shaft diameter may be prepared. Since the length is long, it is necessary to consider measures such as center run-out measures during processing, resulting in poor productivity.
(3) In addition, since the rotor shaft length is long, the mold of the rotor part is also large and expensive, and the workability during other molding is also poor. In addition, workability is similarly poor in the surface treatment.
(4) For example, when used in a water-jet compressor that injects water into a compression working space to cool and seal the space, and the shaft is in contact with the fluid containing air or moisture, it is used for a long time. Rust is generated during this period, causing leakage of the shaft seal part and abnormal wear of the sliding part.
(5) Although the tooth profile dimensions of the rotor portion are the same, the diameter and the shaft length of the shaft portion are different, so that parts cannot be shared, and manufacturing and management are complicated.
[0003]
However, although it is a screw compressor, it is divided into a hollow small diameter portion and a hollow large diameter portion to reduce the weight, and the opposing end faces are to be joined by friction welding. No. 105418 is disclosed, but it is not intended to solve the above-mentioned various problems by using a hollow shaft and joining it by friction welding. Japanese Utility Model Laid-Open No. 56-49311 discloses a technique in which the crankshaft portions are simply connected by splines and an elastic body is injected into the spline connection portions to reduce wear and noise. Further, in a propeller shaft, there is Japanese Utility Model Publication No. 2-71108, in which a groove is formed in one of the propeller shaft and the yoke, and a protrusion engaging with the groove is formed on the other. As shown in Japanese Patent No. 52-25562, a sleeve integrated with an impeller of a compressor is provided, a screw is cut in a hole of the sleeve, and a screw portion of the shaft is received and assembled. The thing is how to make general attachment surely, and does not solve the above-mentioned various problems.
[0004]
[Problems to be solved by the invention]
Therefore, in the first or second, by adopting simple shaft coupling, the same rotor portion can be adopted for many models with different shaft lengths, and the screw rotor material is wasted and the manufacturing process is enormous. It eliminates the high cost because it requires a lot of man-hours. Furthermore, the shaft can be divided and handled easily, the molding machine is downsized, and it is only necessary to process a dedicated shaft among many types. The shaft part can be easily machined to reduce the manufacturing cost, and a vent hole that penetrates from the insertion hole recessed in the rotor shaft or central shaft to the shaft end on the opposite side is drilled so that the shaft coupling can be inserted smoothly. Therefore, the insertion work can be performed easily and reliably, and air can be circulated (breathing action) due to a temperature difference during operation and stop of the recessed portion.
Thirdly, in addition to the first or second problem, it is possible to prevent a wrong assembly between the rotor portion and the rotor shaft, thereby further reducing the manufacturing cost.
Fourth and fifth, in addition to any one of the first to third problems, the central shaft is covered with a synthetic resin. To enable treatment or surface treatment and to facilitate the use of corrosion-resistant materials.
Sixth and seventh, in addition to any one of the first to fifth problems, since the coefficient of linear expansion of the material on the outer side of the center axis is smaller than that of the inner axis, the conduction heat accompanying the compression action To ensure that the mating state is maintained for a long period of time.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a screw rotor for a screw fluid machine. First, in a screw rotor, a central axis is extended to at least one outer end on a rotor portion forming a screw tooth shape and an axis of the rotor portion. And providing a step on the outer end of the central shaft to project a small diameter shaft, and externally fitting a separate shaft with a fitting hole recessed in the small diameter shaft and joining the shaft. The core is characterized in that a vent hole penetrating from the insertion hole recessed in the rotor shaft to the opposite shaft end is formed . Secondly, in a screw rotor of a screw fluid machine, a central axis is extended to at least one outer end of the rotor part forming the screw tooth shape and the axial center of the rotor part, and fitted into the outer end of the central axis. recessed holes, while the shaft joined fitted in the axis of the special make projecting from the small-diameter shaft into fitting Nyuana, substantially axis of the rotor shaft, the insertion hole which is recessed in the central axis A vent hole penetrating the shaft end on the opposite side is formed . Thirdly, in addition to either the first or second technical means, from the first end and the innermost outer end of the small diameter shaft or the recessed insertion hole protruding from the central axis of the rotor portion to the rotor end surface Is characterized in that both shaft ends are set to have substantially the same size across the rotor portion. Fourth, in addition to any one of the first to third technical means, the rotor portion is formed by integrally molding a rotor made of a thermosetting synthetic resin around a metal central axis. And Fifth, in addition to the fourth technical means, the rotor portion is characterized in that the outer surface of the central axis is covered with a synthetic resin of the same quality as the rotor portion. Sixth, in addition to any one of the first or third to fifth technical means, the material of the rotor shaft that is externally joined to the central shaft of the rotor portion has a linear expansion coefficient that is higher than that of the material used for the central shaft. It is a metal material having small properties. Seventh, in addition to any one of the second to fifth technical means, the material used for the central axis of the rotor portion has a property that the linear expansion coefficient is smaller than that of the rotor axis that is fitted and joined to the central axis. It is a metal material.
[0006]
Embodiment
Hereinafter, although the screw fluid machine of the present invention will be described, the screw fluid machine will be described as an example for convenience. Hereinafter, description will be made based on the embodiment of FIGS. As shown in FIG. 1 and FIG. 2, a rotor shaft 1 forming a screw tooth shape and a central shaft 3 are extended to at least one outer end 2 on the axial center of the rotor portion 1, and the outer end of the central shaft 3 is 4, a small-diameter shaft 5 was provided with a step, and a separate rotor shaft 6 having a fitting hole 7 recessed in the small-diameter shaft 5 was externally fitted and axially joined. In this case, preferably, the other end 2a of the rotor portion 1 is similarly provided with the same central shaft 3a, small-diameter shaft 5a, separate rotor shaft 6a, and fitting hole 7a. And, from each of the most initial ends 26, 26a and outermost ends 27, 27a of the small diameter shafts 5, 5a provided on the central shafts 3, 3a of the rotor portion 1 to the outer ends 2, 2a of the rotor portion which is the rotor end surface. The length is set to be substantially the same at both shaft ends with the rotor portion 1 in between. FIG. 2 is a cross-sectional view showing a state before the shaft connection of the screw rotor, and the same parts as those in FIG.
Hereinafter, in the present invention, the rotor portion includes a rotor tooth portion having a screw tooth shape.
[0007]
Further, as shown in FIG. 3, the above-described shaft joining is performed by extending a central shaft 9 to a rotor portion 1c forming a screw tooth shape and at least one outer end 8 on the axial center of the rotor portion 1c. An insertion hole 10 may be recessed in the outer end of the shaft 9, and a shaft joint in which a separate rotor shaft 11 having a small-diameter shaft 12 projecting from the insertion hole 10 may be internally fitted. In this case, preferably, the other end 8a of the rotor portion 1c is also provided with a fitting hole 10a in the outer end of the same central shaft 9a as described above, and a small-diameter shaft 12a projecting from the separately manufactured rotor shaft 11a. A shaft joining means in which the small-diameter shaft 12a is fitted in the fitting hole 10a is similarly taken. In this case, preferably, the outer end 8, 8a of the rotor part which is the rotor end surface from the innermost end 28, 28a and the innermost end 29, 29a of the insertion hole 10, 10a provided in the central axis of the rotor part 1c. The length up to is set to approximately the same size at both shaft ends across the rotor portion 1c.
And as a shaft joining means of each above-mentioned example, a hole diameter is made smaller than a shaft diameter, and a shaft is press-fitted into a fitting hole, or joined by shrinkage. Alternatively, spline processing may be applied to the hole and the shaft to join the shaft, or a screw may be cut into the hole and the shaft to engage the screw.
[0008]
Further, as shown in FIG. 4, the rotor portion 1 d is obtained by integrally molding a rotor made of a thermosetting synthetic resin around a metal central shaft 13. A central shaft 15 is extended to at least one outer end 32 on the metal central shaft 13 of the rotor portion 1d, and a fitting hole 16 is recessed in the outer end of the central shaft 15, and the fitting is performed. The shaft joint of the third embodiment in which a separately manufactured rotor shaft 17 having a small-diameter shaft 18 projecting into the hole 16 was fitted. As shown in FIG. 5, this shape is formed by extending a central shaft 20 covered with a synthetic resin around at least one outer end 35 on the metal central shaft 19 of the rotor portion 1 e. The outer end 21 is provided with a step to project a small diameter shaft 22, and the small diameter shaft 22 is fitted with a fitting hole 24 that is recessed at the end of a rotor shaft 23 made separately from the rotor portion 1 e. The shaft connection of the fourth embodiment may be used. In the third and fourth embodiments, the other ends 32a and 35a are preferably provided with shaft joining means having the same structure as that shown in FIGS. 4 and 5, respectively. The description is omitted by attaching. Furthermore, in this case, preferably, from the first start ends 30 and 30a and the innermost ends 31 and 31a of the fitting holes 16 and 16a provided in the respective central axes of the rotor portion 1d to the outer ends 32 and 32a of the rotor portion. And the length from the most starting ends 33, 33a and the outermost ends 34, 34a of the small-diameter shafts 22, 22a provided on the central axis of the rotor portion 1e to the outer ends 35, 35a of the rotor portion, respectively. Both shaft ends are set to have substantially the same size across the rotor portions 1d and 1e. Further, as these shaft joining means, the hole diameter is made smaller than the shaft diameter, preferably the fitting hole is warmed (the shaft may be cooled) and the shaft is press-fitted into the fitting hole, or as described above. Spline processing may be applied to the shaft to join the shaft, or a screw may be cut into the hole and the shaft for screw engagement. Further, the rotor portion may employ a technical means in which the outer surface of the central axis is covered with a synthetic resin having the same quality as the rotor portion.
[0009]
In each of the first to fourth embodiments described above, the shape of the fitting hole and the small-diameter shaft as the shaft joining means may be a circle, a triangle, a quadrangle, a polygon, etc., and a fitting hole is provided at one end of the central shaft. It is good also as a different shape so that it may be recessed and a small-diameter shaft may protrude in the other end. Further, as shown in FIG. 4, the extended periphery of the metal central shaft 13 of the rotor portion 1d is not covered with the synthetic resin, and further, as shown in FIG. 5, the metal center of the rotor portion 1e. Although the periphery of the shaft 19 is a central shaft 20 coated with a synthetic resin, depending on the conditions of use and the like, the metal core shaft 19 of the rotor portion 1e may be covered with a synthetic resin without being coated with a synthetic resin. Alternatively, the periphery of the metal central shaft 13 of the rotor portion 1d may be covered with a synthetic resin.
[0010]
Furthermore, in addition to any of the embodiments of FIGS. 1 to 5, the rotor shafts 6, 6a, 11, 11a, 17, 17a, 23, 23a have substantially the center axis of the rotor shaft or center. Vent holes 25, 25 a... Penetrating from the respective insertion holes 7, 7 a, 10, 10 a, 16, 16 a, 24, 24 a recessed in the shaft to the shaft end on the opposite side were made. In this case, the substantially axial center means that each of the vent holes 25, 25a... Is geometrical in the present invention because any part of each of the insertion holes 7, 7a, 10, 10a, 16, 16a, 24, 24a may communicate with the outside air. Since it is not an academic axis, it is called an approximate axis (a hole may be drilled in the center axis for manufacturing).
[0011]
Furthermore, the material of the rotor shafts 6, 6 a, 23, and 23 a that are externally joined to the central shaft of the rotor portion is a metal material that has a property of having a smaller linear expansion coefficient than the material used for the central shaft. Alternatively, the material used for the central axis of the rotor portion is a metal material having a property that the linear expansion coefficient is smaller than that of the rotor shafts 11, 11a, 17, and 17a that are fitted and joined to the central axis.
Next, the operation and main actions will be described based on the compressor of FIG. 6. The rotor portion and the separately manufactured rotor shaft are configured by the shapes of the respective embodiments and various shaft joining means. Thus, the appearance is not changed at all, and the function of the screw rotor of the screw fluid machine is not changed. Therefore, the operation of various technical means according to the present invention will be described. Since the rotor part and shaft part are divided, the dimensions of the rotor part (including the rotor tooth part) can be shared, so that it can be mass-produced with a dedicated processing machine, while the shaft part is processed independently by the shaft parts. Then, after completion of each, both are fitted and joined by shrinkage or the like, and are combined into a desired rotor. As a result, the completed screw rotor is stable in both processing quality and performance, and it is possible to greatly reduce the processing man-hours and the manufacturing cost. At the same time, parts can be easily managed by sharing parts.
In addition, since the central shaft is covered with synthetic resin, in addition to the rust prevention effect of the shaft, even if there is a contact in the slight gap between the shaft seal portion between the working chamber and the bearing chamber during operation of the fluid machine, it will be seized. There is nothing.
[0013]
Further, when the central axis of the screw rotor and the rotor shaft are fitted, the air remaining in the recessed portion escapes to the outside from the vent hole formed in the rotor shaft. Therefore, air can be circulated (breathing action) due to a temperature difference between the operation and stop of the recessed portion, and the joining can be ensured.
Furthermore, since the coefficient of linear expansion of the material fitted on the central shaft is smaller than that of the fitted shaft, it acts in a direction in which the fitting is tightened by the conduction heat accompanying the compression action. Therefore, the fitting state can be reliably maintained for a long time. And when a rotor tooth | gear part or a rotor axis | shaft is worn out during a long driving | running | working period, it is only necessary to replace each applicable part at the time of overhaul.
[0014]
【effect】
First or second, since the rotor portion and the shaft portion of the screw rotor are divided, the rotor portion can be processed with the same processing setup as long as the dimensions of the rotor portion are the same. Stable machining quality can be maintained and parts management is easy. In addition, by adopting simple shaft coupling, the same rotor part can be used for many models with different shaft lengths, eliminating waste in the screw rotor material, eliminating the need for a large amount of man-hours for manufacturing, and increasing costs. In addition, the shaft can be divided and easy to handle, and the shaft can be shortened, so the molding machine can be downsized and the shaft can be easily machined using only the dedicated shaft of many models. As a result, the production cost could be greatly reduced. Furthermore, the shaft portion is easy to handle and work because the parts themselves are smaller than the rotor portion even in the process of surface treatment and other complicated manufacturing processes. Furthermore, by making a vent hole penetrating from the insertion hole recessed in the rotor shaft or the central shaft to the shaft end on the opposite side, the shaft coupling is smoothly inserted so that the insertion work can be performed easily and securely. In addition, air circulation (breathing action) can be performed due to a temperature difference during operation and stop of the recessed portion.
Third, in addition to the effects of either the first or the second, it is possible to prevent an assembly error between the rotor portion and the rotor shaft, to make the machining parts common, and to further reduce the manufacturing cost. .
Fourth and fifth, in addition to any of the effects of the first to third, since the central shaft is covered with a synthetic resin, only a necessary portion can be easily rust-prevented as a rust prevention measure for the shaft portion. It is possible to perform treatment or surface treatment, and it is easy to adopt a corrosion resistant material.
Sixth and seventh, in addition to any one of the first to fifth effects, since the linear expansion coefficient of the material that is externally fitted to the central axis is smaller than that of the internally fitted axis, the conduction heat accompanying the compression action This makes it possible to act in a direction in which the fitting is tightened, and to securely hold the fitting state over a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of a screw rotor according to the present invention.
FIG. 2 is a cross-sectional view showing a state of the screw rotor according to the first embodiment of the present invention before shaft joining.
FIG. 3 is a sectional view showing a second embodiment of the screw rotor according to the present invention.
FIG. 4 is a cross-sectional view showing a third embodiment of the screw rotor according to the present invention.
FIG. 5 is a sectional view showing a fourth embodiment of the screw rotor according to the present invention.
FIG. 6 is a schematic cross-sectional view of a main part showing a compressor of a screw rotor.
[Explanation of symbols]
1, 1b to 1e Rotor part 2, 2a, 8, 8a, 32, 32a, 35, 35a Outer end 3, 3a, 9, 9a, 15, 15a, 20, 20a of rotor part Central shaft 4, 4a, 21, 21a Outer ends 5, 5a, 12, 12a, 18, 18a, 22, 22a of the central shaft Small diameter portions 6, 6a, 11, 11a, 17, 17a, 23, 23a Rotor shafts 7, 7a, 10, 10a, 16, 16a, 24, 24a Insertion part 13, 19 Metal center shaft 25, 25a Vent

Claims

In a screw rotor of a screw fluid machine, a central axis is extended to at least one outer end of the rotor portion forming a screw tooth shape and an axial center of the rotor portion, and a step is provided at the outer end of the central axis. projecting a small-diameter shaft, with the shaft of the special make that recessed the insertion hole to the small-diameter shaft externally fitted to the shaft joint, in a substantially axial center of the rotor shaft, insertion hole that is recessed in the rotor shaft A screw rotor having a vent hole penetrating from the shaft end to the opposite side thereof .

In a screw rotor of a screw fluid machine, a central axis is extended to at least one outer end of a rotor portion forming a screw tooth shape and an axial center of the rotor portion, and a fitting hole is recessed in the outer end of the central axis. And a shaft made by projecting a small-diameter shaft into the insertion hole and joining the shaft, and the substantially axial center of the rotor shaft is located on the opposite side of the insertion hole recessed in the central shaft. A screw rotor comprising a vent hole penetrating the shaft end .

The length from the beginning end and the innermost outer end of the small diameter shaft projecting from the central axis of the rotor portion to the rotor end surface is set to approximately the same size at both shaft ends across the rotor portion. The screw rotor according to claim 1 or 2, wherein the screw rotor is formed.

The screw rotor according to any one of claims 1 to 3, wherein the rotor portion is formed by integrally molding a thermosetting synthetic resin rotor around a metal central shaft. .

The screw rotor according to claim 4, wherein the rotor portion is formed by coating the outer surface of the central axis with a synthetic resin having the same quality as the rotor portion.

The material of the rotor shaft that is externally joined to the central shaft of the rotor portion is a metal material having a property that the linear expansion coefficient is smaller than that of the material used for the central shaft. The screw rotor according to claim 5.

The material used for the central axis of the rotor portion is a metal material having a property of having a smaller linear expansion coefficient than that of the rotor shaft fitted and joined to the central axis. The screw rotor according to item 1.