JP3765618B2

JP3765618B2 - Double seal valve

Info

Publication number: JP3765618B2
Application number: JP18488696A
Authority: JP
Inventors: 薫小澤
Original assignee: TOSTE CO.,LTD.
Current assignee: TOSTE CO.,LTD.
Priority date: 1996-07-15
Filing date: 1996-07-15
Publication date: 2006-04-12
Anticipated expiration: 2016-07-15
Also published as: JPH1030736A

Description

【０００１】
【発明の属する技術分野】
本発明は、食品製造、醸造等の機械やプラントにおける液体流通ラインに使用される二重シール弁に関するもので、流路を二重にシールすることにより二液の混合を防止する弁構造に関する。
【０００２】
【従来の技術】
従来におけるこの種の二重シール弁として、上部流路と下部流路との間に形成した連通路に弁座を設け、弁座の内周側座面に主環状パッキンを介して摺接係合する第１弁体を第１弁軸に、また弁座の上部側座面に副環状パッキンを介して押接係合する第２弁体を第２弁軸にそれぞれ設け、第１弁軸及び２弁軸を弁開閉駆動機構により適宜に駆動させることによって、第１弁体及び第２弁体の開閉を行わせるようにしたものがある。各環状パッキンはゴム製のもので、弁座との対向面に凹設されたパッキン取付用嵌合溝に嵌合されて取り付けられている。
【０００３】
【発明が解決しようとする課題】
上記のような二重シール弁において、副環状パッキンは、第２弁体の下動によって弁座の上部側座面に押接されて係合するので、閉弁時に圧縮力が作用するだけで、剪断力はかからないが、主環状パッキンの方は、第１弁体の上下動によってステンレス鋼等からなる弁座の内周側座面に対し軸方向に摺接して係合されるものであって、その摺接面に大きな摩擦抵抗が働くために、パッキン取付用嵌合溝から突出するパッキン部分（以降、接液部分と云う）とその嵌合溝に没入しているパッキン部分（以降、非接液部分と云う）との境界部分に剪断力が生じ、その剪断力が過大になると、パッキンの破損につながる。
【０００４】
また、このような二重シール弁において、各弁体のパッキンは、閉弁時には、弁座の座面に拘束されて圧縮状態にあり、開弁時には拘束が解けて接液部分が膨張状態となるが、この開弁時に、弁内を通過する液体の圧力変動や温度変化によって接液部分の膨張度が著しく大きくなる。しかして、第１弁体の主環状パッキンにあっては、開弁状態から閉弁動作に移る時に、パッキンの接液部分が上記のように大きく膨張した状態で弁座の内周面に突入することによって、その接液部分は過大な剪断力を受け、短期のうちに破損してしまう。
【０００５】
そこで本発明は、上記弁内を通過する液体の圧力変動や温度変化に伴う接液部分の膨張度が非接液部分の体積に対する接液部分の体積の比率に関係し、非接液部分の体積が接液部分の体積に比べて大きければ大きい程、接液部分の膨張度が小さくなると云う点に鑑み、更には開弁状態において主環状パッキンの接液部分を部分的に拘束してやれば開弁時の接液部分の膨張を抑制できることを考慮し、開弁状態から閉弁動作に移る時に主環状パッキンの接液部分に作用する剪断力を極力軽減し、もって主環状パッキンの耐用性を向上させるようにした二重シール弁を提供することを課題とする。
【０００６】
【課題を解決するための手段】
上記の課題を解決するための請求項１に係る二重シール弁は、上部流路１と下部流路２との間に形成した連通路３に弁座６を設け、弁座６の内周側座面６ａに主環状パッキン１２を介して摺接係合する第１弁体７を第１弁軸８に、また弁座６の上部側座面６ｂに副環状パッキン１３を介して押接係合する第２弁体９を、第１弁軸８に摺動可能でばね１１により常時下向きに付勢されるように嵌装される第２弁軸１０にそれぞれ設けると共に、第１弁軸８を弁開閉駆動機構２８に連動連結し、開弁時に第１弁軸８の上動に伴って第２弁体９が第１弁体７に追従移動する二重シール弁において、主環状パッキン１２は、第１弁体７のパッキン取付用嵌合溝７ａから突出するパッキンの接液部分１２ｂが開弁時における液体の圧力変動や温度変化による膨張を抑制されるように、前記パッキン取付用嵌合溝７ａに没入する非接液部分１２ａの断面積を接液部分１２ｂの断面積に比べて十分大きくすると共に、開弁時に接液部分１２ｂの上端縁部が第２弁体９の下広がりテーパ状内周面９ｂの下端部に係合するようにしたことを特徴とする。
【０００７】
請求項２は、請求項１に記載の二重シール弁において、第１弁体７の主環状パッキン１２は、ゴム材にフッ素樹脂材を所要量混入したものから形成されていることを特徴とする。
【０００８】
請求項３は、請求項１または２に記載の二重シール弁において、弁座６の内周側座面６ａには、フッ素樹脂材のコーティング層またはライニング層が形成されていることを特徴とする。
【０００９】
【発明の実施の形態】
図１は、本発明に係る二重シール弁の全体をａ−ａ線で二分した下半分の縦断面図で、図２は上半分を示している。これらの図において、１は上部流路、２は下部流路で、これらの流路１，２は互いに平行または交差方向に形成されていて、両流路１，２の間には連通路３が形成され、また両流路１，２における連通路３と同軸上に対向する部位に上部開口部４及び下部開口部５が形成され、そして連通路３には弁座６が装着されている。上部流路１及び下部流路２に、それぞれ飲料液または洗浄液を流通させるようになっている。
【００１０】
７は、弁座６の内周側に係合する第１弁体で、上部開口部４から連通路３を通って下部開口部５側に挿入された第１弁軸８の中間軸部８ｂの下端部に一体形成されている。この第１弁体７の下部には中空状の下部軸部８ｃが同軸一体形成され、また中間軸部８ｂの上部には上部軸部８ａが、通常はねじ結合により同軸に連設されている（図１及び図２には、中間軸部８ｂと上部軸部８ａとが一体に形成されたものとして図示している）。これら上部軸部８ａと中間軸部８ｂと下部軸部８ｃとによって第１弁軸８が形成される。
【００１１】
９は、第１弁体７の上側に位置して弁座６の上部側に上方より押接係合する第２弁体で、第１弁軸８の上部軸部８ａから中間軸部８ｂにわたって套嵌された第２弁軸１０の下端部に一体に形成されており、この第２弁軸１０は、後述するようにコイルばねからなる第１ばね１１によって常時下向きに付勢され、それにより第２弁体９を弁座６の上部側に押し付けている。尚、この第２弁軸１０は、上部軸部１０ａとこれにねじ結合された下部軸部１０ｂとからなるもので、下部軸部１０ｂの下端部に第２弁体９が形成される。
【００１２】
図３以降の図面をも参照して明らかなように、第１弁体７には、弁座６の内周側座面６ａに摺動可能に密接する主環状パッキン１２がパッキン取付用嵌合溝７ａに嵌合されて取り付けられ、第２弁体９には、弁座６の上部側座面６ｂに上方より密接する副環状パッキン１３がパッキン取付用嵌合溝９ａに嵌合されて取り付けられている。上部流路１の上部開口部４には、この上部開口部４から上方へ突出する第２弁軸１０の下部軸部１０ｂを摺動可能に支持する環状部材１４が設けられ、この環状部材１４は、ヨーク１５の基部１５ａと、これの下端部で下部軸部１０ｂに密接するパッキン１６を含んで構成される。また、下部流路２の下部開口部５には、この下部開口部５から下方へ突出する第１弁軸８の下部軸部８ｃを摺動可能に支持する環状部材１７が設けられ、この環状部材１７は、スリーブ１８の径大基部１８ａと、これの上端部で下部軸部８ｃに密接するパッキン１９を含んで構成される。
【００１３】
図１に示すように、第２弁軸１０の下部軸部１０ｂには洗浄液供給口２０が設けられ、この洗浄液供給口２０は、連通孔２１を介して、第１弁軸８の中間軸部８ｂに設けられた内部通路２２に通じ、この内部通路２２は、中間軸部８ｂの下端部に放射状に設けられた複数の洗浄液噴出孔２３に通じている。しかして、洗浄液供給口２０より洗浄液を供給すると、その洗浄液は、連通孔２１より中間軸部８ｂの内部通路２２に入り、下端部の各洗浄液噴出孔２３から、第１弁体７と第２弁体９と弁座６との間に形成される環状室２４内に噴出して、この環状室２３の内部を洗浄した後、複数の通孔２５を通って下部軸部８ｃ内部の排出路２６から外部に排出される。尚、洗浄液供給口２０には洗浄液ホース接続用の口金２７がヨーク１５の窓１５ａを通して取り付けられる。
【００１４】
また、図２を参照すると、この図において２８は、第１弁体７及び第２弁体９の開閉を司る第１の弁開閉駆動機構であり、この弁開閉駆動機構２８は、第１弁軸８の上部軸部８ａをピストンロッドとし、これに固定したピストン２９を固定シリンダ３０内に嵌装したエアシリンダからなるもので、固定シリンダ３０内の上部にばね受け３１が配置され、このばね受け３１とピストン２９との間には、このピストン２９と第２弁軸１０との間に介装された第１ばね１１よりばね力の大きい第２ばね３２と、前記ピストンロッド８ａに固定され且つ前記ばね受け３１に対し伸縮自在に連結されて、前記第２ばね３２の伸びを一定範囲に制限するばね制限ストッパー３３とが介装され、そして固定シリンダ３０には、ピストン２９を隔ててその上下両室３０ａ，３０ｂに対しエアの給排を行うエア給排ポート３４，３５が設けられている。
【００１５】
前記ばね受け３１は、第２ばね３２の一端部を受けるリング状のばね受け本体３１ｏと、これと同心状に一体形成された円筒部材３１ａとからなり、前記ばね制限ストッパー３３は、ピストンロッド（第１弁軸８の上部軸部８ａ）に外嵌されて定位置に固定されると共にばね受け３１の円筒部材３１ａに摺動可能に内嵌される円筒部材３３ａからなるもので、常時は図２に示すように、第２ばね３２の付勢力で両円筒部材３１ａ，３３ａの先端係合部が互いに係合することによって、ばね受け３１とストッパー３３とが最大に伸びた状態で連結され、それにより第２ばね３２がそれ以上伸びないように制限されている。
【００１６】
従って、この第１の弁開閉駆動機構２８によると、固定シリンダ３０内の上下両室３０ａ，３０ｂのいずれにも圧力エアが供給されていない時には、図２に示すように、ピストン２９と第２弁軸１０の上部軸部１０ａとの間に介装された第１ばね１１の付勢力により、第１弁軸８が上方へ、第２弁軸１０が下方へそれぞれ付勢されて、第１弁体７が主環状パッキン１２を介して弁座６の内周側座面６ａに密接係合すると共に、第２弁体９が副環状パッキン１３を介して弁座６の上部側座面６ｂに密接係合し、図３に示すような弁全閉状態となる。
【００１７】
そして、エア給排ポート３５より固定シリンダ３０の下部室３０ｂに圧力エアが供給されると、ピストン２９が第２ばね３２の付勢力に抗して上昇し、これに伴い前記ストッパー３３の円筒状部材３３ａが収縮作動して、第１弁軸８が上動を開始し、その途上で第１弁体７の上端部が図４に示すように第２弁体９の内周側下部に当接し、この当接状態で第１弁体７が第２弁体９を押し上げて共上がりしながら、両弁体７，９が弁座６から上方へ離間し、しかしてピストンロッド８ａの上端側に嵌装されたストローク設定リングＲが固定シリンダ３０の上壁部３０ｃに当接することで、ピストン２９が上動限位置に至り、第１弁体７及び第２弁体９は、図５に示すような弁全開状態となる。
【００１８】
また、上記の弁全開状態において固定シリンダ３０の下部室３０ｂの圧力エアを排出させることにより、ばね受け３１が固定シリンダ３０の上壁部３０ｃに押し付けられたまま、ピストン２９が第２ばね３２の付勢力によって下降し、これに伴い第１弁軸８及び第２弁軸１０が下動して、第１弁体７及び第２弁体９は図３に示すような弁全閉状態に戻る。尚、弁全閉状態（図３参照）と弁全開状態（図５参照）でのピストン２９のストロークＳａは、固定シリンダ３０の上壁部３０ｃに当接する上記ストローク設定リングＲによって設定される。
【００１９】
また、図１及び図２に示す弁全閉状態において、エア給排ポート３４から固定シリンダ３０の上部室３０ａに圧力エアが供給されると、前記ばね制限ストッパー３３によって第２ばね３２の伸びが制限されているから、上部室３０ａの圧力上昇によりピストン２９が下方に押されて下降し、それに伴い第１弁軸８が第１ばね１１に付勢力に抗して下動し、第１弁体７の主環状パッキン１２が弁座６の内周側座面６ａを下方へ摺動して離間し、図６に示すように第１弁体７のみが僅かに開いた弁部分開状態となる。このように、固定シリンダ３０の上部室３０ａに圧力エアを供給することにより、第１弁軸８を単独で下動させて、第１弁体７のみを開弁状態とすることができる。この場合、ピストン２９は、図２に示される位置から下降を開始し、後述する第２シリンダ３７の上端に当接して停止する。従って、そのストロークは同図に示すＳｂとなり、このストロークＳｂ分だけ第１弁軸８が第２弁軸１０と独立して上下動することになる。
【００２０】
前記第１の弁開閉駆動機構２８の下方には、同じくエアシリンダからなる第２の弁体開閉駆動機構３６が設けられている。この第２の弁体開閉駆動機構３６は、第１の弁開閉駆動機構２８の固定シリンダ３０下部にこれと連通して連設された第２シリンダ３７と、この第２シリンダ３７に内嵌されると共に第２弁軸１０の上部軸部１０ａに外嵌された状態で所定ストローク上下動する第２ピストン３８と、この第２ピストン３８を下動限位置に付勢する第３ばね３９と、第２ピストン３８の下部室３０ａに対するエアの給排を行うエア給排ポート４０とから構成されている。
【００２１】
図２において、４１は第２ピストン３８の下動限位置を規制するストッパーで、第２シリンダ３７の下壁部側に形成され、また４２は第２ピストン３８の上動限位置を規制するストッパーで、第２シリンダ３７の上壁部側に形成されている。しかして、第２ピストン３８は、下動限位置規制ストッパー４１と上動限位置規制ストッパー４２との間において、ピストン３８の外周側上端部３８ａと上動限位置規制ストッパー４２との間隔に相当するストロークＳ１を上下動するが、第３ばね３９により下動限位置に付勢された第２ピストン３８の内周側上端部３８ｂと、第１ばね１１により閉弁位置に付勢された第２弁軸１０の上部軸部１０ａに突設されたストッパー４３との間に、前記ストロークＳ１よりも短い軸方向の遊びＳ２が設けられていることから、この第２ピストン３８が下動限位置から上動限位置までストロークＳ１上動することにより、第２弁軸１０は、前記ストロークＳ１と前記軸方向遊びＳ２との差（Ｓ１−Ｓ２）分だけ上動することになる。このように、第３ばね３９で下動限位置に付勢される第２ピストン３８の内周側上端部３８ｂと、第２ばね３２で閉弁位置に付勢される第２弁軸１０側のストッパー４３との間に、第２ピストン３８のストロークＳ１より短い軸方向遊びＳ２を設けることにより、第２ばね３２の付勢力を第２弁軸１０に対して確実に作用させることができる。
【００２２】
この第２の弁開閉駆動機構３６にあっては、図２のように第２ピストン３８が下動限位置に保持されている状態から、エア給排ポート４０より第２シリンダ３７の下部室３７ａに圧力エアが供給されると、第２ピストン３８が上動を開始するが、そのピストン３８の内周側上端部３８ｂが第２弁軸１０のストッパー４２に当たるまでは、第２弁軸１０は第２弁体９を閉じる下降位置に保持されたままである。しかして、第２弁軸１０は、第２ピストン３８の内周側上端部３８ｂがストッパー４２に当たった後、第２ピストン３８の上動に伴って押し上げられ、このピストン３８の外周側上端部３８ａが上動限位置規制ストッパー４２に当たるまで上動し、それにより図７に示すように第２弁体９のみが僅かに開いた弁部分開状態となる。また、上記下部室３７ａの圧力エアを抜くことにより、第２ピストン３８が第３ばね３９により押し下げられると共に、第２弁軸１０は第２ばね３２により下動し、第２弁体９は閉弁状態となる。また、第２シリンダ３７の上部室３７ｂと前記第１弁開閉駆動機構２８における固定シリンダ３０の下部室３０ｂとは互いに連通している。
【００２３】
次に、本発明の特徴である第１弁体７及びこれに取り付けられる主環状パッキン１２について図８によって説明すると、主環状パッキン１２は、開弁時の断面構造を示す図８の（Ａ）から分かるように、第１弁体７のパッキン取付用嵌合溝７ａに没入する非接液部分１２ａの断面積が当該嵌合溝７ａから突出する接液部分１２ｂの断面積に比べて十分大きくなるようにパッキン取付用嵌合溝７ａに取り付けられている。この場合、非接液部分１２ａの断面積は接液部分１２ｂの断面積の８〜１０倍とされる。図８（Ｂ）は、弁全開状態において主環状パッキン１２が弁座６の内周側座面６ａに密接係合している状態を示すもので、この主環状パッキン１２は、内周側座面６ａに拘束されて圧縮される。
【００２４】
開弁時において弁内を通過する液体の圧力変動や温度上昇に伴う接液部分の膨張度は非接液部分の体積に対する接液部分の体積の比率に関係し、非接液部分の体積が接液部分の体積に比べて大きければ大きい程、接液部分の膨張度が小さくなることから、上記のように主環状パッキン１２の非接液部分１２ａの断面積を接液部分１２ｂの断面積に比べて十分大きくとることによって、接液部分の膨張度を小さくすることが可能となる。従って、図５に示すような開弁状態にある第１弁体７が下動して図３及び図８（Ａ）に示すような閉弁状態に移る際、弁内を通過する液体の圧力変動や温度上昇に伴う接液部分１２ｂの膨張度が極力小さく制限されているため、主環状パッキン１２が弁座６の内周側座面６ａに突入係合するときに接液部分１２ｂに作用する剪断力が極力軽減され、それにより主環状パッキン１２の損傷や破損が防止される。
【００２５】
図８（Ｃ）は、閉弁状態にあった第１弁体７が第２弁体９を押し上げて共上がりしながら、両弁体７，９が弁座６から上方へ離間して弁全開状態となるときの主環状パッキン１２の断面形状を示すもので、第１弁軸の上動に伴い第１弁体７の上端部７ｂが、第２弁体９の下広がりテーパ状内周面９ｂの下部に当接すると共に、主環状パッキン１２の接液部分１２ｂの上端縁部が同図のように第１弁体上端部７ｂの下側でテーパ状内周面９ｂに係合するようになっている。このように弁全開時に接液部分１２ｂの上端縁部が第２弁体９のテーパ状内周面９ｂに係合することによって、この接液部分１２ｂがテーパ状内周面９ｂにより部分的に拘束された状態となり、それによって弁内を通過する液体の圧力変動や温度上昇に伴う接液部分１２ｂの膨張を抑制することができる。また、接液部分１２ｂの上端縁部が図８（Ｃ）の実線図示のように第２弁体９のテーパ状内周面９ｂに係合した状態において接液部分１２ｂが液体による加熱や加圧作用を受けると、接液部分１２ｂの上端縁部がテーパ状内周面９ｂに沿って拘束力の弱まる上向きへ逃げるように変形し、それにより接液部分１２ｂ全体が同図仮想線図示のようにパッキン径方向に膨出変形することを阻止することができる。
【００２６】
上記のようにパッキン取付用嵌合溝７ａに没入する主環状パッキン１２の非接液部分１２ａの断面積を接液部分１２ｂの断面積に比べて十分大きくすると共に、開弁時に接液部分１２ｂの上端縁部が第２弁体９のテーパ状内周面９ｂの下端部に係合するように構成したことによって、弁全開状態状態から閉弁動作に移る時に主環状パッキン１２の接液部分１２ｂに作用する剪断力を極力軽減し、もって主環状パッキン１２の耐用性を向上させることができる。
【００２７】
また、第１弁体７の主環状パッキン１２を、ゴム材にフッ素樹脂材を所要量混入したものから形成することによって、主環状パッキン１２の摺動摩擦抵抗を軽減し、耐用性を向上させることができる。また、弁座６の内周側座面６ａに、フッ素樹脂材のコーティング層またはライニング層を形成することによって、内周側座面６ａの耐用性の向上を図ることができる。
【００２８】
以上のような構成を有する二重シール弁の使用において、第１の弁開閉駆動機構２８における固定シリンダ３０の下部室３０ｂに圧力エアが供給されていない状態のときには、図１〜図３に示すように、第１弁体７が主環状パッキン１２を介して弁座６の内周側座面６ａに密接係合すると共に、第１ばね１１により押し下げる第２弁軸１０によって第２弁体９が副環状パッキン１３を介して弁座６の上部側座面６ｂに押接係合して、第１弁体７及び第２弁体９が共に閉じた弁全閉状態となり、しかして上部流路１と下部流路２とを連通する連通路３は、下部流路２側の第１弁体７と上部流路１側の第２弁体９とによって二重シールされた状態で閉塞され、上部流路１を流れる液体と下部流路２を流れる液体との混合が防止される。
【００２９】
そして、上記固定シリンダ３０の下部室３０ｂに圧力エアが供給されると、図４に示すように第１弁体７が第２弁体９を押し上げて共上がりしながら、両弁体７，９が弁座６から上方へ十分に離間して図５に示すような弁全開状態となり、これにより連通路３が開通し、この連通路３を介して上部流路１と下部流路２とを連通させることができる。
【００３０】
また、粘性の高い液体等のように洗浄のし難い液体を使用する時は、第１弁体７及び第２弁体９の一方を閉じ、他方を僅かに開けて、開けた方のパッキン部分を洗浄液により洗浄しながら、その洗浄液を排出する。例えば、上部流路１に高粘性の飲料水を流通させ、下部流路２に洗浄液を流通させる場合には、固定シリンダ３０の上部室３０ａに圧力エアを供給すると、上部室３０ａの圧力上昇によりピストン２９が伸びを制限されている第２ばね３２と共に下降し、それに伴い第１弁軸８が下動して、第１弁体７の主環状パッキン１２が弁座６の内周側座面６ａを下方へ摺動して離間し、図６に示すように第１弁体７のみが僅かに開いた弁部分開状態となる。しかして、下部流路２からの洗浄液は、図６の矢印で示すように、第１弁体７と弁座６との間の間隙を通って、第１弁体７と第２弁体９と弁座６との間に形成される環状室２４内に導入され、その間に第１弁体７の主環状パッキン１２部分及び環状室２の内部を洗浄し、その後第１弁軸８の下部軸部８ｃ内部の排出路２６を通って外部に排出される。
【００３１】
また、下部流路２に高粘性の飲料水を流通させ、上部流路１に洗浄液を流通させる場合には、第２の弁開閉駆動機構３６における第２シリンダ３７の下部室３７ａに圧力エアを供給すると、第２ピストン３８が上動する途上でこのピストン３８にて第２弁軸１０が押し上げられ、第２ピストン３８が所定ストローク（Ｓ１−Ｓ２）上動することにより、第２弁軸１０が同じストロークだけ上動して、図７に示すように第２弁体９のみが僅かに開いた弁部分開状態となる。しかして、上部流路１からの洗浄液は、図７の矢印で示すように、第２弁体９と弁座６の上部側座面６ｂとの間の間隙を通過し更に第１弁体７と第２弁体９と弁座６との間に形成される環状室２４内を巡回して、第１弁体７の副環状パッキン１３部分及び環状室２の内部を洗浄した後、第１弁軸８の下部軸部８ｃ内部の排出路２６を通って外部に排出される。
【００３２】
【発明の効果】
請求項１に係る二重シール弁によれば、第１弁体に取り付けられる主環状パッキンの非接液部分の断面積を接液部分の断面積に比べて十分大きくとることによって、弁内を通過する液体の圧力変動や温度上昇に伴う接液部分の膨張度が極力小さく制限され、このため開弁状態から閉弁状態に移る際、主環状パッキンが弁座の内周側座面に突入係合するときに、主環状パッキンの接液部分に作用する剪断力が極力軽減され、それにより主環状パッキンの損傷や破損が防止される。
【００３３】
また、開弁時に前記接液部分の上端縁部が第２弁体の下広がりテーパ状内周面の下端部に係合するようになっているため、この接液部分がテーパ状内周面により部分的に拘束された状態となり、それによって弁内を通過する液体の圧力変動や温度上昇に伴う当該接液部分の膨張を抑制することができ、また接液部分の上端縁部が第２弁体のテーパ状内周面に係合した状態において接液部分が液体による加熱や加圧作用を受けると、接液部分の上端縁部がテーパ状内周面に沿って拘束力の弱まる上向きへ逃げるように変形し、それにより接液部分全体がパッキン径方向に膨出変形することを阻止することができる。
【００３４】
上記のように、主環状パッキンの非接液部分の断面積を接液部分の断面積に比べて十分大きくすると共に、開弁時に接液部分の上端縁部が第２弁体のテーパ状内周面の下端部に係合するように構成しているため、開弁状態から閉弁動作に移る時に主環状パッキンの接液部分に作用する剪断力を極力軽減し、もって主環状パッキンの耐用性を向上させることができる。
【００３５】
請求項２によれば、第１弁体の主環状パッキンを、ゴム材にフッ素樹脂材を所要量混入したものから形成することによって、主環状パッキンの摺動摩擦抵抗を軽減し、耐用性を向上させることができる。
【００３６】
請求項３によれば、弁座の内周側座面に、フッ素樹脂材のコーティング層またはライニング層を形成することによって、内周側座面の耐用性の向上を図ることができる。
【図面の簡単な説明】
【図１】本発明に係る二重シール弁の下半分を示す縦断面図であり、ａ−ａ線が上半分との分割線である。
【図２】同二重シール弁の上半分を示す縦断面図である。
【図３】弁全閉状態にある二重シール弁中心部を示す縦断面図である。
【図４】弁全閉状態から開弁状態に移行している状態を示す二重シール弁の中心部の縦断面図である。
【図５】弁全開状態にある二重シール弁中心部を示す縦断面図である。
【図６】第１弁体が僅かに開いた弁部分開状態を示す縦断面図である。
【図７】第２弁体が僅かに開いた弁部分開状態を示す縦断面図である。
【図８】（Ａ）は開弁状態での第１弁体の主環状パッキンを示す拡大縦断面図、（Ｂ）は閉弁状態での第１弁体の主環状パッキンを示す拡大縦断面図、（Ｃ）は閉弁時に主環状パッキンの上端縁部が第２弁体のテーパ状内周面に係合した状態を示す拡大縦断面図である。
【符号の説明】
１上部流路
２下部流路
３連通路
６弁座
６ａ内周側座面
６ｂ上部側座面
７第１弁体
７ａパッキン取付用嵌合溝
８第１弁軸
９第２弁体
１０第２弁軸
１１第１ばね
１２主環状パッキン
１２ａ非接液部分
１２ｂ接液部分
１３副環状パッキン[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a double seal valve used for a liquid distribution line in machinery and plants for food production, brewing, etc., and relates to a valve structure that prevents mixing of two liquids by sealing a flow path double.
[0002]
[Prior art]
As a conventional double seal valve of this type, a valve seat is provided in the communication path formed between the upper flow path and the lower flow path, and is in sliding contact with the inner peripheral seat surface of the valve seat via a main annular packing. A first valve body is provided on the first valve shaft, and a second valve body is provided on the second valve shaft to be pressed and engaged with the upper seat surface of the valve seat via a secondary annular packing. In addition, there is one in which the first valve body and the second valve body are opened and closed by appropriately driving the two valve shafts by a valve opening / closing drive mechanism. Each of the annular packings is made of rubber, and is fitted and attached to a packing mounting fitting groove that is recessed on the surface facing the valve seat.
[0003]
[Problems to be solved by the invention]
In the double seal valve as described above, the secondary annular packing is pressed against and engaged with the upper seat surface of the valve seat by the downward movement of the second valve body, so that only the compression force acts when the valve is closed. Although the shearing force is not applied, the main annular packing is engaged by sliding in the axial direction against the inner circumferential side seat surface of the valve seat made of stainless steel or the like by the vertical movement of the first valve body. Since a large frictional resistance acts on the sliding contact surface, a packing part protruding from the packing mounting fitting groove (hereinafter referred to as a liquid contact part) and a packing part immersed in the fitting groove (hereinafter referred to as a liquid contact part) When a shearing force is generated at the boundary portion with the non-wetted portion) and the shearing force becomes excessive, the packing is damaged.
[0004]
In such a double seal valve, the packing of each valve body is in a compressed state by being restrained by the seat surface of the valve seat when the valve is closed, and when the valve is opened, the restraint is released and the wetted part is in an expanded state. However, when this valve is opened, the degree of expansion of the wetted part is significantly increased due to pressure fluctuations and temperature changes of the liquid passing through the valve. Therefore, in the case of the main annular packing of the first valve body, when moving from the valve open state to the valve closing operation, the wetted part of the packing rushes into the inner peripheral surface of the valve seat in a state where it has greatly expanded as described above. By doing so, the wetted part is subjected to excessive shearing force and is damaged in a short time.
[0005]
Therefore, the present invention relates to the ratio of the volume of the wetted part to the volume of the wetted part with respect to the volume of the wetted part, and the degree of expansion of the wetted part accompanying the pressure fluctuation and temperature change of the liquid passing through the valve. In view of the fact that the larger the volume compared to the volume of the wetted part, the smaller the degree of expansion of the wetted part, and further, if the wetted part of the main annular packing is partially constrained in the valve open state, it will open. Considering that expansion of the wetted part at the time of valve can be suppressed, the shearing force acting on the wetted part of the main annular packing is reduced as much as possible when the valve is moved from the open state to the valve closing operation, thereby improving the durability of the main annular packing. It is an object of the present invention to provide a double seal valve that is improved.
[0006]
[Means for Solving the Problems]
The double seal valve according to claim 1 for solving the above problem is provided with a valve seat 6 in the communication passage 3 formed between the upper flow path 1 and the lower flow path 2, and the inner periphery of the valve seat 6. The first valve body 7 slidably engaged with the side seat surface 6a via the main annular packing 12 is pressed against the first valve shaft 8, and the upper side seat surface 6b of the valve seat 6 is pressed against the side seat surface 6a via the sub annular packing 13. The second valve body 9 to be engaged is provided on each of the second valve shafts 10 that are slidable on the first valve shaft 8 and are always urged downward by the spring 11. In a double seal valve in which the second valve body 9 moves following the first valve body 7 as the first valve shaft 8 moves upward when the valve 8 is opened, the main annular packing 12 shows that the liquid contact portion 12b of the packing protruding from the packing mounting fitting groove 7a of the first valve body 7 is affected by liquid pressure fluctuation and temperature change when the valve is opened. The cross-sectional area of the non-wetted part 12a immersed in the packing mounting fitting groove 7a is made sufficiently larger than the cross-sectional area of the wetted part 12b so that the expansion is suppressed. The upper end edge of 12b is engaged with the lower end of the taper-shaped inner peripheral surface 9b spreading downward from the second valve body 9.
[0007]
A second aspect of the present invention is the double seal valve according to the first aspect, wherein the main annular packing 12 of the first valve body 7 is formed of a rubber material mixed with a required amount of a fluororesin material. To do.
[0008]
A third aspect of the present invention is the double seal valve according to the first or second aspect, wherein a coating layer or a lining layer of a fluororesin material is formed on the inner peripheral side seating surface 6a of the valve seat 6. To do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a vertical sectional view of a lower half obtained by dividing the entire double seal valve according to the present invention by aa line, and FIG. 2 shows the upper half. In these drawings, 1 is an upper flow path, 2 is a lower flow path, and these flow paths 1 and 2 are formed in parallel or intersecting directions. In addition, an upper opening 4 and a lower opening 5 are formed at portions that are coaxially opposed to the communication path 3 in both flow paths 1 and 2, and a valve seat 6 is mounted on the communication path 3. . A beverage liquid or a cleaning liquid is circulated through the upper flow path 1 and the lower flow path 2, respectively.
[0010]
Reference numeral 7 denotes a first valve body that engages with the inner peripheral side of the valve seat 6, and an intermediate shaft portion 8 b of the first valve shaft 8 that is inserted from the upper opening portion 4 through the communication passage 3 to the lower opening portion 5 side. Are integrally formed at the lower end of the. A hollow lower shaft portion 8c is coaxially formed integrally with the lower portion of the first valve body 7, and an upper shaft portion 8a is normally coaxially connected to the upper portion of the intermediate shaft portion 8b by screw coupling. (In FIGS. 1 and 2, the intermediate shaft portion 8b and the upper shaft portion 8a are illustrated as being integrally formed). The first valve shaft 8 is formed by the upper shaft portion 8a, the intermediate shaft portion 8b, and the lower shaft portion 8c.
[0011]
Reference numeral 9 denotes a second valve body which is located on the upper side of the first valve body 7 and is pressed and engaged with the upper side of the valve seat 6 from above, and extends from the upper shaft portion 8a of the first valve shaft 8 to the intermediate shaft portion 8b. The second valve shaft 10 is integrally formed at the lower end portion of the second valve shaft 10 which is fitted, and the second valve shaft 10 is always urged downward by a first spring 11 made of a coil spring, as will be described later. The second valve body 9 is pressed against the upper side of the valve seat 6. The second valve shaft 10 includes an upper shaft portion 10a and a lower shaft portion 10b screwed to the upper shaft portion 10a. A second valve body 9 is formed at the lower end portion of the lower shaft portion 10b.
[0012]
As will be apparent with reference to FIG. 3 and subsequent drawings, the first valve body 7 has a main annular packing 12 slidably in close contact with the inner peripheral seat surface 6a of the valve seat 6 for fitting for packing. The secondary annular packing 13 that is in close contact with the upper seat surface 6b of the valve seat 6 from above is fitted into the packing mounting fitting groove 9a and attached to the second valve body 9. It has been. The upper opening 4 of the upper flow path 1 is provided with an annular member 14 that slidably supports the lower shaft portion 10b of the second valve shaft 10 protruding upward from the upper opening 4. Includes a base portion 15a of the yoke 15 and a packing 16 in close contact with the lower shaft portion 10b at the lower end portion thereof. In addition, the lower opening 5 of the lower flow path 2 is provided with an annular member 17 that slidably supports the lower shaft portion 8c of the first valve shaft 8 that protrudes downward from the lower opening 5. The member 17 includes a large-diameter base portion 18a of the sleeve 18 and a packing 19 that is in close contact with the lower shaft portion 8c at the upper end portion thereof.
[0013]
As shown in FIG. 1, a cleaning liquid supply port 20 is provided in the lower shaft portion 10 b of the second valve shaft 10, and this cleaning liquid supply port 20 is connected to the intermediate shaft portion of the first valve shaft 8 via a communication hole 21. The internal passage 22 communicates with a plurality of cleaning liquid ejection holes 23 provided radially at the lower end of the intermediate shaft portion 8b. When the cleaning liquid is supplied from the cleaning liquid supply port 20, the cleaning liquid enters the internal passage 22 of the intermediate shaft portion 8 b through the communication hole 21, and the first valve body 7 and the second valve 2 from the cleaning liquid ejection holes 23 at the lower end. After ejecting into the annular chamber 24 formed between the valve body 9 and the valve seat 6 to clean the inside of the annular chamber 23, the discharge passage inside the lower shaft portion 8 c passes through the plurality of through holes 25. 26 is discharged to the outside. A base 27 for connecting a cleaning liquid hose is attached to the cleaning liquid supply port 20 through a window 15 a of the yoke 15.
[0014]
Referring to FIG. 2, reference numeral 28 denotes a first valve opening / closing drive mechanism that controls opening and closing of the first valve body 7 and the second valve body 9. The valve opening / closing drive mechanism 28 includes a first valve opening / closing drive mechanism 28. The upper shaft portion 8a of the shaft 8 is a piston rod, and is composed of an air cylinder in which a piston 29 fixed to the piston rod is fitted in a fixed cylinder 30, and a spring receiver 31 is disposed in the upper portion of the fixed cylinder 30. A second spring 32 having a spring force larger than that of the first spring 11 interposed between the piston 29 and the second valve shaft 10 is fixed between the receiver 31 and the piston 29, and the piston rod 8a. In addition, a spring limit stopper 33 that is connected to the spring receiver 31 so as to be extendable and restricts the extension of the second spring 32 to a certain range is interposed, and the fixed cylinder 30 is separated by a piston 29. Up and down Chamber 30a, the air supply and discharge ports 34, 35 for performing air supply and discharge are provided to 30b.
[0015]
The spring receiver 31 includes a ring-shaped spring receiver body 31o that receives one end of the second spring 32, and a cylindrical member 31a that is integrally formed concentrically therewith, and the spring limit stopper 33 is a piston rod ( The first valve shaft 8 is composed of a cylindrical member 33a that is externally fitted to the upper shaft portion 8a) and fixed in place and is slidably fitted to the cylindrical member 31a of the spring receiver 31. As shown in FIG. 2, the end portions of the cylindrical members 31a and 33a are engaged with each other by the urging force of the second spring 32, so that the spring receiver 31 and the stopper 33 are connected in a state where they extend to the maximum. As a result, the second spring 32 is restricted from extending further.
[0016]
Therefore, according to the first valve opening / closing drive mechanism 28, when no pressure air is supplied to either of the upper and lower chambers 30a, 30b in the fixed cylinder 30, as shown in FIG. Due to the urging force of the first spring 11 interposed between the upper shaft portion 10a of the valve shaft 10, the first valve shaft 8 is urged upward and the second valve shaft 10 is urged downward, respectively. The valve body 7 is closely engaged with the inner peripheral side seat surface 6a of the valve seat 6 through the main annular packing 12, and the second valve body 9 is engaged with the upper side seat surface 6b of the valve seat 6 through the sub annular packing 13. And the valve is fully closed as shown in FIG.
[0017]
When pressure air is supplied from the air supply / discharge port 35 to the lower chamber 30b of the fixed cylinder 30, the piston 29 rises against the urging force of the second spring 32, and accordingly the cylindrical shape of the stopper 33 is increased. When the member 33a contracts, the first valve shaft 8 starts to move upward, and the upper end of the first valve body 7 contacts the lower part on the inner peripheral side of the second valve body 9 as shown in FIG. In this contact state, the first valve body 7 pushes up the second valve body 9 and rises together, while the both valve bodies 7 and 9 are separated upward from the valve seat 6, and thus the upper end side of the piston rod 8 a When the stroke setting ring R fitted to the upper surface 30c of the fixed cylinder 30 comes into contact with the piston 29, the first valve body 7 and the second valve body 9 are shown in FIG. The valve is fully opened as shown.
[0018]
In addition, by discharging the pressure air in the lower chamber 30b of the fixed cylinder 30 in the fully opened state, the piston 29 is moved to the second spring 32 while the spring receiver 31 is pressed against the upper wall portion 30c of the fixed cylinder 30. The first valve shaft 8 and the second valve shaft 10 move downward due to the urging force, and the first valve body 7 and the second valve body 9 return to the valve fully closed state as shown in FIG. . The stroke Sa of the piston 29 in the valve fully closed state (see FIG. 3) and the valve fully opened state (see FIG. 5) is set by the stroke setting ring R that contacts the upper wall portion 30c of the fixed cylinder 30.
[0019]
1 and FIG. 2, when the pressure air is supplied from the air supply / discharge port 34 to the upper chamber 30a of the fixed cylinder 30, the second spring 32 is extended by the spring limit stopper 33. Since the pressure is limited, the piston 29 is pushed downward by the pressure increase in the upper chamber 30a, and the first valve shaft 8 moves downward against the urging force against the first spring 11, and the first valve The main annular packing 12 of the body 7 slides downward on the inner peripheral side seating surface 6a of the valve seat 6 and is separated so that only the first valve body 7 is slightly opened as shown in FIG. Become. Thus, by supplying pressure air to the upper chamber 30 a of the fixed cylinder 30, the first valve shaft 8 can be moved down alone, and only the first valve body 7 can be opened. In this case, the piston 29 starts to descend from the position shown in FIG. 2 and stops after coming into contact with the upper end of the second cylinder 37 described later. Therefore, the stroke is Sb shown in the figure, and the first valve shaft 8 moves up and down independently of the second valve shaft 10 by this stroke Sb.
[0020]
Below the first valve opening / closing drive mechanism 28, a second valve body opening / closing drive mechanism 36, which is also formed of an air cylinder, is provided. The second valve body opening / closing drive mechanism 36 is fitted into the second cylinder 37 and a second cylinder 37 connected to the lower portion of the fixed cylinder 30 of the first valve opening / closing drive mechanism 28 in communication therewith. And a second piston 38 that moves up and down for a predetermined stroke while being fitted on the upper shaft portion 10a of the second valve shaft 10, and a third spring 39 that urges the second piston 38 to the lower limit position; The air supply / discharge port 40 is configured to supply / discharge air to / from the lower chamber 30a of the second piston 38.
[0021]
In FIG. 2, 41 is a stopper that regulates the lower limit position of the second piston 38, and is formed on the lower wall side of the second cylinder 37, and 42 is a stopper that regulates the upper limit position of the second piston 38. Thus, it is formed on the upper wall portion side of the second cylinder 37. Thus, the second piston 38 corresponds to the distance between the upper end 38a on the outer peripheral side of the piston 38 and the upper movement limit position restriction stopper 42 between the lower movement limit position restriction stopper 41 and the upper movement limit position restriction stopper 42. The stroke S <b> 1 is moved up and down, but the upper end 38 b on the inner peripheral side of the second piston 38 biased to the lower limit position by the third spring 39 and the valve closing position biased by the first spring 11. Since the axial play S2 shorter than the stroke S1 is provided between the stopper 43 projecting from the upper shaft portion 10a of the two-valve shaft 10, the second piston 38 is in the lower limit position. As a result, the second valve shaft 10 moves upward by the difference (S1−S2) between the stroke S1 and the axial play S2. Thus, the inner peripheral side upper end 38b of the second piston 38 urged to the lower limit position by the third spring 39, and the second valve shaft 10 side urged to the valve closing position by the second spring 32. By providing an axial play S2 shorter than the stroke S1 of the second piston 38 between the stopper 43 and the stopper 43, the urging force of the second spring 32 can be reliably applied to the second valve shaft 10.
[0022]
In the second valve opening / closing drive mechanism 36, the lower chamber 37a of the second cylinder 37 is provided from the air supply / discharge port 40 from the state where the second piston 38 is held at the lower limit position as shown in FIG. When the pressurized air is supplied to the second valve shaft 10, the second piston 38 starts to move upward, but until the inner peripheral side upper end 38 b of the piston 38 hits the stopper 42 of the second valve shaft 10, The second valve body 9 remains held at the lowered position. Thus, the second valve shaft 10 is pushed up along with the upward movement of the second piston 38 after the inner peripheral upper end 38b of the second piston 38 hits the stopper 42, and the outer peripheral upper end of the piston 38 is pushed up. The valve 38a moves upward until it hits the upper movement limit position restricting stopper 42, so that only the second valve body 9 is slightly opened as shown in FIG. Further, by removing the pressure air from the lower chamber 37a, the second piston 38 is pushed down by the third spring 39, the second valve shaft 10 is moved down by the second spring 32, and the second valve body 9 is closed. It becomes a valve state. The upper chamber 37b of the second cylinder 37 and the lower chamber 30b of the fixed cylinder 30 in the first valve opening / closing drive mechanism 28 communicate with each other.
[0023]
Next, the first valve body 7 which is a feature of the present invention and the main annular packing 12 attached to the first valve body 7 will be described with reference to FIG. 8. The main annular packing 12 shows a sectional structure when the valve is opened. As can be seen from the above, the cross-sectional area of the non-wetted part 12a that immerses in the packing mounting fitting groove 7a of the first valve body 7 is sufficiently larger than the cross-sectional area of the wetted part 12b that protrudes from the fitting groove 7a. It is attached to the fitting groove 7a for packing attachment. In this case, the cross-sectional area of the non-wetted part 12a is 8 to 10 times the cross-sectional area of the wetted part 12b. FIG. 8 (B) shows a state in which the main annular packing 12 is in close contact with the inner peripheral side seat surface 6a of the valve seat 6 in the fully opened state. The surface 6a is constrained and compressed.
[0024]
The degree of expansion of the wetted part due to pressure fluctuation or temperature rise of the liquid passing through the valve when the valve is opened is related to the ratio of the volume of the wetted part to the volume of the wetted part, and the volume of the wetted part is Since the degree of expansion of the wetted part decreases as the volume of the wetted part increases, the cross-sectional area of the non-wetted part 12a of the main annular packing 12 is changed to the cross-sectional area of the wetted part 12b as described above. By taking a sufficiently large value, the degree of expansion of the wetted part can be reduced. Therefore, when the first valve body 7 in the open state as shown in FIG. 5 moves down and moves to the closed state as shown in FIGS. 3 and 8A, the pressure of the liquid passing through the valve Since the degree of expansion of the wetted part 12b due to fluctuations and temperature rise is limited to a minimum, the main annular packing 12 acts on the wetted part 12b when the main annular packing 12 enters and engages with the inner peripheral seat surface 6a of the valve seat 6. The shearing force to be reduced is reduced as much as possible, thereby preventing the main annular packing 12 from being damaged or broken.
[0025]
FIG. 8 (C) shows that the first valve body 7 that has been in the closed state pushes up the second valve body 9 and moves upward while the both valve bodies 7 and 9 are spaced apart from the valve seat 6 to fully open the valve. The cross-sectional shape of the main annular packing 12 when in a state is shown, and the upper end portion 7b of the first valve body 7 extends downward from the second valve body 9 along with the upward movement of the first valve shaft. 9b so that the upper edge of the liquid contact portion 12b of the main annular packing 12 engages with the tapered inner peripheral surface 9b below the first valve body upper end portion 7b as shown in FIG. It has become. As described above, when the valve is fully opened, the upper edge of the liquid contact portion 12b is engaged with the tapered inner peripheral surface 9b of the second valve body 9, so that the liquid contact portion 12b is partially formed by the tapered inner peripheral surface 9b. As a result, the expansion of the liquid contact portion 12b due to the pressure fluctuation or temperature rise of the liquid passing through the valve can be suppressed. Further, when the upper edge of the liquid contact portion 12b is engaged with the tapered inner peripheral surface 9b of the second valve body 9 as shown by the solid line in FIG. 8C, the liquid contact portion 12b is heated or heated by the liquid. When the pressure action is applied, the upper edge of the liquid contact portion 12b is deformed so as to escape upward along the tapered inner peripheral surface 9b so that the restraining force is weakened. In this way, it is possible to prevent the bulge and deformation in the packing radial direction.
[0026]
As described above, the cross-sectional area of the non-wetted part 12a of the main annular packing 12 immersed in the packing mounting fitting groove 7a is sufficiently larger than the cross-sectional area of the wetted part 12b, and the wetted part 12b is opened when the valve is opened. The upper edge portion of the main ring packing 12 is engaged with the lower end portion of the tapered inner peripheral surface 9b of the second valve body 9, so that the liquid contact portion of the main annular packing 12 is shifted from the fully open state to the valve closing operation. The shearing force acting on 12b can be reduced as much as possible, so that the durability of the main annular packing 12 can be improved.
[0027]
Further, by forming the main annular packing 12 of the first valve body 7 from a rubber material mixed with a required amount of a fluororesin material, the sliding frictional resistance of the main annular packing 12 is reduced and the durability is improved. Can do. Further, by forming a coating layer or a lining layer of a fluororesin material on the inner peripheral side seat surface 6a of the valve seat 6, it is possible to improve the durability of the inner peripheral side seat surface 6a.
[0028]
When the double seal valve having the above-described configuration is used, when the pressure air is not supplied to the lower chamber 30b of the fixed cylinder 30 in the first valve opening / closing drive mechanism 28, it is shown in FIGS. As described above, the first valve body 7 is closely engaged with the inner peripheral side seat surface 6 a of the valve seat 6 via the main annular packing 12, and the second valve body 9 is pushed by the second valve shaft 10 pushed down by the first spring 11. Is pressed and engaged with the upper seat surface 6b of the valve seat 6 via the auxiliary annular packing 13, so that the first valve body 7 and the second valve body 9 are both closed, and the upper flow The communication path 3 that connects the path 1 and the lower flow path 2 is closed in a double-sealed state by the first valve body 7 on the lower flow path 2 side and the second valve body 9 on the upper flow path 1 side. Mixing of the liquid flowing through the upper flow path 1 and the liquid flowing through the lower flow path 2 is prevented.
[0029]
When pressurized air is supplied to the lower chamber 30b of the fixed cylinder 30, the first valve body 7 pushes up the second valve body 9 and rises together as shown in FIG. 5 is sufficiently spaced upward from the valve seat 6 so that the valve is fully opened as shown in FIG. 5, whereby the communication path 3 is opened, and the upper flow path 1 and the lower flow path 2 are connected via the communication path 3. Can communicate.
[0030]
Also, when using a liquid that is difficult to clean, such as a highly viscous liquid, close one of the first valve body 7 and the second valve body 9 and slightly open the other, and the opened packing portion The washing liquid is discharged while washing with the washing liquid. For example, when high-viscosity drinking water is circulated in the upper flow path 1 and cleaning liquid is circulated in the lower flow path 2, if pressure air is supplied to the upper chamber 30a of the fixed cylinder 30, the pressure in the upper chamber 30a increases. The piston 29 is lowered together with the second spring 32 whose extension is restricted, and the first valve shaft 8 is moved downward accordingly, and the main annular packing 12 of the first valve body 7 is moved to the inner peripheral side seating surface of the valve seat 6. 6a is slid downward and separated, and only the first valve body 7 is slightly opened as shown in FIG. Accordingly, the cleaning liquid from the lower flow path 2 passes through the gap between the first valve body 7 and the valve seat 6 as shown by the arrow in FIG. 6, and the first valve body 7 and the second valve body 9. Is introduced into an annular chamber 24 formed between the valve seat 6 and the main annular packing 12 portion of the first valve body 7 and the interior of the annular chamber 2 during that time, and then the lower portion of the first valve shaft 8. It is discharged to the outside through the discharge path 26 inside the shaft portion 8c.
[0031]
In addition, when highly viscous drinking water is circulated through the lower flow path 2 and cleaning liquid is circulated through the upper flow path 1, pressure air is supplied to the lower chamber 37 a of the second cylinder 37 in the second valve opening / closing drive mechanism 36. When supplied, the second valve shaft 10 is pushed up by the piston 38 while the second piston 38 is moving upward, and the second piston 38 is moved upward by a predetermined stroke (S1-S2). Are moved upward by the same stroke, and only the second valve body 9 is slightly opened as shown in FIG. Accordingly, the cleaning liquid from the upper flow path 1 passes through the gap between the second valve body 9 and the upper seat surface 6b of the valve seat 6 as indicated by the arrow in FIG. And the inside of the annular chamber 24 formed between the second valve body 9 and the valve seat 6 to wash the sub annular packing 13 portion of the first valve body 7 and the interior of the annular chamber 2, The valve shaft 8 is discharged to the outside through the discharge passage 26 inside the lower shaft portion 8c.
[0032]
【The invention's effect】
According to the double seal valve of the first aspect, by taking the cross-sectional area of the non-wetted part of the main annular packing attached to the first valve body sufficiently larger than the cross-sectional area of the wetted part, The degree of expansion of the wetted part due to pressure fluctuations and temperature rise of the passing liquid is limited as much as possible, so when moving from the valve open state to the valve closed state, the main annular packing enters the inner peripheral seat surface of the valve seat When engaged, the shearing force acting on the liquid contact portion of the main annular packing is reduced as much as possible, thereby preventing the main annular packing from being damaged or broken.
[0033]
Further, when the valve is opened, the upper edge of the liquid contact portion is adapted to engage with the lower end of the tapered inner peripheral surface spreading downward from the second valve body. Therefore, it is possible to suppress the expansion of the wetted part due to pressure fluctuation and temperature rise of the liquid passing through the valve, and the upper edge of the wetted part is the second edge. When the wetted part is heated or pressurized by the liquid while it is engaged with the tapered inner peripheral surface of the valve body, the upper edge of the wetted part rises upward along the tapered inner peripheral surface. It is possible to prevent the entire wetted part from bulging and deforming in the packing radial direction.
[0034]
As described above, the cross-sectional area of the non-wetted part of the main annular packing is made sufficiently larger than the cross-sectional area of the wetted part, and the upper edge of the wetted part is within the tapered shape of the second valve body when the valve is opened. Since it is configured to engage with the lower end of the peripheral surface, the shearing force acting on the liquid contact part of the main annular packing is reduced as much as possible when the valve is moved from the open state to the valve closing operation. Can be improved.
[0035]
According to claim 2, by forming the main annular packing of the first valve body from a rubber material mixed with a required amount of fluororesin material, the sliding frictional resistance of the main annular packing is reduced and the durability is improved. Can be made.
[0036]
According to the third aspect, the durability of the inner peripheral side seating surface can be improved by forming a coating layer or a lining layer of a fluororesin material on the inner peripheral side seating surface of the valve seat.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a lower half of a double seal valve according to the present invention, and an aa line is a dividing line with an upper half.
FIG. 2 is a longitudinal sectional view showing an upper half of the double seal valve.
FIG. 3 is a longitudinal sectional view showing a center portion of a double seal valve in a valve fully closed state.
FIG. 4 is a longitudinal sectional view of a central portion of a double seal valve showing a state in which the valve is in a fully open state to a valve open state.
FIG. 5 is a longitudinal sectional view showing a center portion of a double seal valve in a fully opened state of the valve.
FIG. 6 is a longitudinal sectional view showing a valve partial open state in which the first valve body is slightly opened.
FIG. 7 is a longitudinal sectional view showing a valve partial open state in which a second valve body is slightly opened.
8A is an enlarged longitudinal sectional view showing the main annular packing of the first valve body in a valve open state, and FIG. 8B is an enlarged longitudinal sectional view showing the main annular packing of the first valve body in a valve closed state. FIG. 4C is an enlarged longitudinal sectional view showing a state in which the upper end edge of the main annular packing is engaged with the tapered inner peripheral surface of the second valve body when the valve is closed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper flow path 2 Lower flow path 3 Communication path 6 Valve seat 6a Inner peripheral side seat surface 6b Upper side seat surface 7 1st valve body 7a Packing attachment fitting groove 8 1st valve shaft 9 2nd valve body 10 2nd Valve shaft 11 First spring 12 Main annular packing 12a Non-wetted part 12b Wetted part 13 Sub-annular packing

Claims

A valve seat is provided in a communication path formed between the upper flow path and the lower flow path. In addition, a second valve body that is press-engaged to the upper seat surface of the valve seat via a sub-annular packing is slidable on the first valve shaft so as to be constantly urged downward by a spring. The first valve shaft is linked to the valve opening / closing drive mechanism, and the second valve body follows the first valve body as the first valve shaft moves upward when the valve is opened. In the double seal valve, the main annular packing is designed so that the liquid contact portion of the packing protruding from the packing mounting fitting groove of the first valve body can be prevented from expanding due to liquid pressure fluctuation or temperature change when the valve is opened. In addition, the cross-sectional area of the non-wetted part immersed in the packing mounting fitting groove should be sufficiently larger than the cross-sectional area of the wetted part. , Dual seal valve, characterized in that the upper edge of the wetted portion at the time of valve opening is adapted to engage the lower end of the lower spreading tapered inner circumferential surface of the second valve body.

The double seal valve according to claim 1, wherein the main annular packing of the first valve body is formed from a rubber material mixed with a required amount of a fluororesin material.

The double seal valve according to claim 1 or 2, wherein a coating layer or a lining layer of a fluororesin material is formed on an inner peripheral side seating surface of the valve seat.