JP2005054614A

JP2005054614A - Screw compressor

Info

Publication number: JP2005054614A
Application number: JP2003206650A
Authority: JP
Inventors: Fumio Takeda; 文夫武田; Hirochika Kametani; 裕敬亀谷; Eiichiro Tanaka; 英一郎田中; Masayuki Kasahara; 雅之笠原; Hitoshi Nishimura; 仁西村; Masakazu Aoki; 優和青木
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2003-08-08
Filing date: 2003-08-08
Publication date: 2005-03-03
Anticipated expiration: 2023-08-08
Also published as: JP3978162B2

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a screw compressor which has a low discharge pressure, a high efficiency, no need of a forced oil supply unit, high reliability of a bearing, which can be reduced in size and which is suitable as an on-vehicle fuel battery. <P>SOLUTION: The screw compressor includes a male rotor 1 having three teeth, a female rotor 2 having five teeth, with a tooth form having a large tooth space volume and a rotor volume angle which closes at a compression starting time without delay. Both bearings 4 and 5 of intake side and discharge side eliminate the need of the forced oil supply unit as grease lubricating. The grease having small consistency softening even at high temperature and small loss torque by a low sound is used. A structure that an intake channel 53 for forming a part of an intake passage is formed between an inner surface of a casing 3 and an intake side bearing housing 16, a duct 22 is provided at the outside of the casing 3 and a discharge side bearing housing 59 is cooled with the intake air in the duct, is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は低圧・大風量を供給するのに好適なスクリュー圧縮機に関し、特に、車載用燃料電池に使用される空気圧縮機として好適なものである。
【０００２】
【従来の技術】
従来、燃料電池は水素と酸素を結合する化学反応を利用して電力を生み出すエネルギ変換器の一種であり、排気されるガスは水蒸気のみなので、環境対応の面や、水素エネルギーが石油等の化石燃料に変わる次世代のエネルギーと期待されることから近年、急速に燃料電池自動車の開発が進められている。
【０００３】
燃料電池用の水素は高圧タンクに充填し、車に搭載するか、メタノール等から改質器で取り出す方法がある。一方、酸素は通常は大気に含まれているものを利用し、空気を圧縮して燃料電池内に取り込み、含有する酸素を反応させている。
【０００４】
従って、燃料電池の出力向上あるいは小型化のためには、単位大きさ当たりの出力増加が必要である。そのためには、水素と酸素が結合する反応を活発に促進する必要があり、多くは酸素の供給量を高めるために供給する空気を大気圧以上に昇圧している。しかし、供給圧力が高すぎても、未反応の酸素を含む空気は圧力を持ったまま燃料電池から排出されるため、エネルギーロスが増大する。そこで、エネルギー効率を考慮して空気の供給圧力は現在０．１５から０．２ＭＰａの低圧としている。
【０００５】
また、車載用に用いられる燃料電池に空気を供給する圧縮機は特に小型、軽量で高性能且つ低騒音が望まれる。低圧用スクリューロータの歯形については、従来吐出圧０．７ＭＰａの２段構成の定置式オイルフリースクリュー圧縮機の高圧段機又は低圧段機を流用しており、吐出圧が０．１５〜０．２ＭＰａの低圧専用の特別のロータは使用されていなかった。
【０００６】
軸受の潤滑方法については特許文献１に記載のスクリュー式車載用過給機のものがある。この過給機は雄、雌両ロータの吸入側と吐出側の軸受をエンジンの潤滑油を利用し、外部からの強制潤滑としている。
なお、騒音に対する防音構造については配慮が為されていない。
【０００７】
【特許文献１】特開平６−３１７１７２号公報
【発明が解決しようとする課題】
車載用燃料電池向けの圧縮機に対しては小型、軽量で且つ高性能、低騒音が望まれる。そこで、小型、高性能とするためにはロータの歯形を小さくして低圧（０．１５〜０．２ＭＰａ）に適した歯形とする必要がある。また、燃料電池車はモータで駆動されるため、エンジン（内燃機関）では必須であった潤滑系がなくなり、このため圧縮機の軸受を強制潤滑するためには、圧縮機自体に、給油及び排油を行うための油圧ポンプによる潤滑系を設ける必要があった。このため、圧縮機が大きく且つ複雑になる欠点があった。更に、燃料電池自動車はモータで駆動されるため、エンジン自動車に比べて騒音が低く、このため圧縮機の騒音が目立つようになるから、圧縮機の低騒音化が望まれる。
【０００８】
本発明の目的は、高効率で、軸受部への強制給油も必要がなく、それによって小形化できるスクリュー圧縮機を得ることにある。
本発明の他の目的は、吐出側軸受や吸入側軸受を効果的に冷却することにより、これらの軸受の信頼性を向上できるスクリュー圧縮機を得ることにある。
本発明の更に他の目的は、低騒音化を図ることのできるスクリュー圧縮機を得ることにある。
【０００９】
【課題を解決するための手段】
上記の目的を達成するため本発明は、タイミングギヤで互いに非接触で噛合い回転する雄・雌一対のロータと、これらのロータを収納すると共に吸入通路と吐出通路を有するケーシングと、前記各ロータの吸入側及び吐出側を支持する軸受と、前記ケーシングに設けられ前記吸入側軸受を収容する吸入側軸受ハウジングと、前記ケーシングに設けられ前記吐出側軸受を収容する吐出側軸受ハウジングとを備えたスクリュー圧縮機において、前記ケーシング内面と前記吸入側軸受ハウジング外面との間に設けられ前記吸入通路の一部を形成する吸入流路と、
吸入側軸受ハウジングと吐出側軸受ハウジングのそれぞれの軸貫通部に設けられたシール機構と、前記吸入側と吐出側の軸受の潤滑に用いられ、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースとを有すると共に、前記雄ロータ径を１としたとき、前記雌ロータ径を０．８８以上、雄ロータと雌ロータとの軸間距離を０．６９以下、雄ロータの長さを１．１以下にしたことを特徴とする。
【００１０】
ここで、雄ロータの巻角を、吸入側で圧縮開始位置にある雄ロータ溝の吐出側端面が、ケーシングの吐出側端面において、雌ロータの溝との連通が断たれる角度に構成すると良い。
【００１１】
本発明の第２の特徴は、タイミングギヤで互いに非接触で噛合い回転する雄・雌一対のロータと、これらのロータを収納すると共に吸入通路と吐出通路を有するケーシングと、前記各ロータの吸入側及び吐出側を支持する軸受と、前記ケーシングに設けられ前記吸入側軸受を収容する吸入側軸受ハウジングと、前記ケーシングに設けられ前記吐出側軸受を収容する吐出側軸受ハウジングとを備えたスクリュー圧縮機において、前記ケーシング内面と前記吸入側軸受ハウジング外面との間に設けられ前記吸入通路の一部を形成する吸入流路と、吸入側軸受ハウジングと吐出側軸受ハウジングのそれぞれの軸貫通部に設けられたシール機構と、前記吸入側と吐出側の軸受の潤滑に用いられ、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースと、前記吐出側軸受ハウジング側のケーシング外側に取り付けられ、該ケーシング及びケーシングに設けられた吸入通路との間に隙間を形成するように配置され且つ前記吸入側軸受ハウジング側が閉じられたダクトとを備え、前記ダクトは、前記吐出側軸受ハウジング側に、ダクト内への吸入用開口部を有すると共に、該吸入用開口部の部分を除き密閉空間を形成するように構成したことにある。
【００１２】
本発明の第３の特徴は、タイミングギヤで互いに非接触で噛合い回転する雄・雌一対のロータと、これらのロータを収納すると共に吸入通路と吐出通路を有するケーシングと、前記各ロータの吸入側及び吐出側を支持する軸受と、前記ケーシングに設けられ前記吸入側軸受を収容する吸入側軸受ハウジングと、前記ケーシングに設けられ前記吐出側軸受を収容する吐出側軸受ハウジングとを備えたスクリュー圧縮機において、前記ケーシング内面と前記吸入側軸受ハウジング外面との間に設けられ前記吸入通路の一部を形成する吸入流路と、吸入側軸受ハウジングと吐出側軸受ハウジングのそれぞれの軸貫通部に設けられたシール機構と、前記吸入側と吐出側の軸受の潤滑に用いられ、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースと、前記吐出側軸受ハウジングの外周部に設けられた冷却水ジャケットとを備えることにある。
【００１３】
本発明の第４の特徴は、タイミングギヤで互いに非接触で噛合い回転する雄・雌一対のロータと、これらのロータを収納すると共に吸入通路と吐出通路を有するケーシングと、前記各ロータの吸入側及び吐出側を支持する軸受と、前記吸入側軸受を収容する吸入側軸受ハウジングと、前記吐出側軸受を収容する吐出側軸受ハウジングとを備えたスクリュー圧縮機において、前記ケーシング内面と前記吸入側軸受ハウジング外面との間に設けられ前記吸入通路の一部を形成する吸入流路と、吸入側軸受ハウジングと吐出側軸受ハウジングのそれぞれの軸貫通部に設けられたシール機構と、前記吸入側と吐出側の軸受の潤滑に用いられ、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースと、前記ロータへの吸入空間又は前記ロータ間に形成される圧縮空間に水を噴霧するための水噴霧用ノズルとを設けたことにある。
【００１４】
更に、上記スクリュー圧縮機において、圧縮され吐出された圧縮空気を他部に供給するための吐出空気配管と、この吐出空気配管に設けられ吐出温度を検出するための温度センサと、前記水噴射ノズルに水を供給するための水噴霧配管と、該水噴射配管に設けられた電動弁と、この電動弁を駆動するためのドライバと、前記温度センサからの検出信号に基づいて、前記水噴射配管の電動弁を制御する制御装置とを備えるようにすると良い。
【００１５】
また、前記各ロータの表面または前記ケーシングの内周面の少なくとも一方に、耐蝕性金属をメッキするか耐水性樹脂をコーティングする、或いはロータの歯溝を有するローブ部及びケーシングを耐蝕性金属又は耐水性樹脂にするとなお良い。
【００１６】
本発明の第５の特徴は、タイミングギヤで互いに非接触で噛合い回転する雄・雌一対のロータと、これらのロータを収納すると共に吸入通路と吐出通路を有するケーシングと、前記各ロータの吸入側及び吐出側を支持する軸受と、前記吸入側軸受を収容する吸入側軸受ハウジングと、前記吐出側軸受を収容する吐出側軸受ハウジングとを備えたスクリュー圧縮機において、前記ケーシング内面と前記吸入側軸受ハウジング外面との間に設けられ前記吸入通路の一部を形成する吸入流路と、吸入側軸受ハウジングの軸貫通部に設けられたシール機構と、前記軸受の潤滑に用いられ、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースと、前記ケーシングの外側に該ケーシングとの間に空間を形成するように弾性材を介して取り付けられた防音カバーとを備えることにある。
【００１７】
ここで、前記防音カバーは、吸入側が閉端に構成され、吐出側軸受のハウジング部付近には該防音カバー内に圧縮機への空気を導くための吸入用開口部が設けられ、該吸入用開口部を除いてカバー内に密閉空間を形成するように吐出側軸受ハウジング側のケーシングに取り付けられるようにするのが良い。
【００１８】
上記において、スクリュー圧縮機は、雄ロータ歯数を３枚、雌ロータ歯数を５枚とし、更に雄ロータの最大回転数を少なくとも１６０００ｍｉｎ^−１にすると共に、雌ロータをインバータ駆動の高周波モータ等により直結駆動する構成にすると良い。
【００１９】
【発明の実施の形態】
本実施例は、ロータの歯形を小型で低吐出圧においても高効率が得られる歯形とし、ロータの軸受を吸入、吐出両側ともグリース潤滑として強制給油を不要にして小型化を図ると共に、圧縮機の低騒音化も図ろうとするものである。
【００２０】
まず、小型で高性能なロータ歯形とするため、理論吸い込み容積を大きくし、漏洩を小さくする。理論吸い込み容積を大きくするためには歯数を少なくすると共にロータ溝を深くし、ロータの溝間の漏れを生ずるブローホール面積をできるだけ小さくする。また、圧縮室側から吸入室側への漏洩通路を形成するシールライン長をできるだけ小さくできる歯形とし、且つ圧縮開始時のロータ溝が閉じ遅れを生じないロータの巻き角とする。
【００２１】
強制潤滑手段を廃止するため、軸受の潤滑をすべてグリース潤滑とし、軸受を冷却する手段を設ける。さらに、低騒音化を図るために、ケーシングの外周に騒音を遮断することが可能な防音構造のカバーを、ケーシングの振動が伝達しないように設ける、等の工夫をした。
【００２２】
以下、本発明の具体的実施例を図１〜図１３を用いて説明する。
図１に本発明の第１実施例を示す。低圧で高効率な雄ロータ１と雌ロータ２が共に噛み合った状態でケーシング３の中に収納されている。各ロータの吐出側軸部は吐出側軸受ハウジング５９内の吐出側軸受４により回転自在に支持されており、各吸入側軸部は吸入ポートを形成するＳケーシング９の吸入側軸受ハウジング１６内の吸入側軸受５により回転自在に支持されている。吐出側軸受４は組み合わせアンギュラ軸受を採用しており、ハウジングの圧縮室側には円管状の仕切板１４を介して接触式シール（オイルシール）６を配置しており、更に圧縮室側にはパージ穴１５を設け、そのまた先のロータ側には非接触式シール（カーボンシール）７を設けている。
【００２３】
吐出側軸部の軸端側には同様に接触式シール（オイルシール）６を設け、その先の端部には各々タイミングギヤ１２を設けており、雄、雌両ロータはタイミングギヤ１２により非接触で回転可能に構成されている。
【００２４】
両ロータの吸入側軸部は吐出側軸部と同様に、吸入側軸受５と圧縮室を形成するロータとの間に円管状の仕切板１４を介して、接触式シール（オイルシール）６が設けられている。なお、両ロータの吸入側軸部端は軸受カバー８で塞がれており、両側の軸受とも軸受ハウジング内に封入したグリースで潤滑を行う。ここで、吐出側軸受４は両側を接触式シール６で密閉されているので、グリースが漏れることなく軸受を潤滑できる。また、吸入側軸受５も、一方は接触シール６で密閉されており、他方は軸受カバー８により塞がれているのでグリースが漏れることはない。
【００２５】
なお、燃料電池用空気圧縮機は雄ロータの最大回転数が１６０００ｒｐｍにもなり、グリース及び軸受の温度上昇が厳しいため、グリースは特に高温で調度の低下が少なく且つ低温での損失トルクが小さい高速・高温用に適したグリースを用いる。吸入側軸受ハウジング１６は、図１３に示すように、Ｓケーシング９の内側と軸受ハウジング１６との間に形成された軸方向吸入流路５３から吸入する空気で冷却される。吸入流路５３からの吸入空気はロータ溝内に充填（吸入）される。吸入側軸受ハウジング１６は吸入流路５３の中に補強用のリブ５４を雄、雌ロータ側に各々設けており、そのリブ５４の取り付け方向は、ロータ軸の中心線から４５度上方としており、圧縮によるガス圧がロータに作用する方向に合わせてある。Ｓケーシング９のロータ下部の圧縮室側（内側端面）は、圧縮開始時のロータ溝の吸入側端面をシールするための端面を形成している。
【００２６】
図１に戻り、吸入ポートを形成するＳケーシング９には、吸入フィルタや消音器（図示せず）と接続される吸入管１０が接続されている。また、ロータの吐出側軸端に設けたタイミングギヤ１２はタイミングギヤカバ１１で密閉されており、タイミングギヤカバ１１内の下部に充填されているオイルをタイミングギヤ１２ではねかけ、潤滑が行われる。また、雌ロータの吐出側軸端部はタイミングギヤカバ１１を貫通し、モータと接続するためのカップリング１３が設けられている。なお、タイミングギヤカバ１１の軸貫通部にも接触式シール（オイルシール）６を設け、充填されているオイルが漏れることがないようにしている。
【００２７】
図２は図１に示す圧縮機と同様の圧縮機と高速モータとを一体型に直結した実施例を示す。図２に示すように、雌ロータ２の吐出側軸を長くしてモータロータ１９を嵌合し、モータのステータ２０を固定したモータケーシング６０をモータアダプタ１７を介して圧縮機のケーシングに取り付けて一体化している。本実施例では雌ロータ駆動としているが、その理由を以下述べる。本実施例では低吐出圧用の歯形として雄ロータの歯数を３枚、雌ロータの歯数を５枚としており、雄ロータの回転数は１６０００ｍｉｎ^−１（１６０００ｒｐｍ）に達するようにする必要がある。雄ロータの回転数が最大で１６０００ｍｉｎ^−１の場合、雌ロータの回転数は最大で９６００ｍｉｎ^−１となるから、本実施例では雌ロータを駆動することにより最大回転数１００００ｍｉｎ^−１程度のモータによる直結駆動を可能とし、より安価なモータで構成することができるようにしている。
６４はモータを冷却するためにモータケーシング６０に形成された水冷ジャケットである。なお、水冷ジャケット６４による水冷式を採用する代わりに空冷式のモータを使用することも可能である。
【００２８】
図８により、低吐出圧に適したロータの歯形について説明する。低吐出圧用のロータでは圧縮過程にあるロータ溝間の圧力比が小さいため、歯数を少なくしても圧力差によるロータ溝間の漏れが増加することがなく、歯数を少なくすることが可能である。歯数を少なくすれば、ロータ周方向に対する歯溝の幅を大きく取れ、溝を深くすることも可能になり、ロータ断面積に対する空気を吸入する溝面積の比を示す歯形係数を大きく取れる利点がある。即ち、歯形係数を大きくとれることにより、歯形によって形成されるロータの歯溝容積も大きく取れるため、圧縮中のロータ溝から吸入空間への漏洩隙間を形成するシールラインからの漏れを一定とすると、吸入した空気量に対する漏れ量の割合を減少でき、この結果性能向上を図ることができる。
【００２９】
本実施例では、図８に示すように、歯数は雄を３枚、雌を５枚とし、溝を深くするためにロータ間距離５０に対する雄ロータ径４８の割合をできるだけ大きくした。但し、雌ロータ径４９に対して雌ロータの歯厚が必要最小限得られる寸法を雄ロータの最大値としている。また、ロータの噛み合い部に生じる漏洩隙間を形成するシールラインの長さを最小とするため、雌ロータ前進面歯先の円弧の半径（前進面歯先円弧半径）５６はできるだけ大きくし、雄ロータ歯先の放物線の焦点距離５７は小さくし、雄ロータ歯先の放物線につながる円弧の半径５８も小さくした。更に、ケーシング３と雄ロータの歯面と雌ロータの歯面とで形成されるロータ溝間の漏れを生じるブローホール面積を決定する雌ロータ後進面歯先の円弧の半径（後進面歯先円弧半径）５５もできるだけ小さくした。なお、雄、雌ロータの他の部分の歯形は、上記円弧及び放物線により互いに創生される形状とする。上記に基づき、溝容積をできるだけ大きくし、漏洩隙間を形成するシールライン長さをできるだけ小さくし、ブローホール面積もできるだけ小さくすることのできる歯形の具体的形状を以下に寸法比で示す。即ち、雄ロータの径を基準として、雌ロータ径を０．８８６以上、軸間距離を０．６８６以下、雌ロータ前進面歯先円弧半径を０．０４４以上、雌ロータ後進面歯先円弧半径を０．０１７以下、雄ロータ歯先放物線焦点距離を０．０８０以下、雄ロータ歯先円弧半径を０．０１以下とし、更に雄ロータの長さを雄ロータの径に対して比を１．０６以下にすると良い。
【００３０】
また、吸入側端面でロータが噛み合い圧縮を開始したときに、雄ロータの圧縮を開始した溝が、吐出側端面で隣の雌ロータ側の吸入中の溝とつながった状態である「閉じ込み遅れ」を生じない条件として雄ロータの巻角を２００°以下とする。閉じ込み遅れについて、図１１と図１２を用いて説明する。図１１は、吸入側から見た圧縮を開始するタイミング（時点）での雄ロータ溝５１及び雌ロータ溝５２の状態を示す。雄ロータは、図１１において右回転、雌ロータは左回転で圧縮が進行する。なお、ロータ溝は吸入側から見て雄ロータは左回転方向、雌ロータは右回転方向にねじれている。そこで、吸入側から見た吐出端面部でのロータ溝の状態を図１２に示す。図１２は、圧縮を開始した雄ロータ溝の吐出側端面位置での状態を表わしており、図１２の状態では圧縮開始の溝５１はケーシングの内壁でシールされ、雌ロータ側の溝とのつながりはない状態に構成されている。
【００３１】
もし、雄ロータの巻き角が大きいと、圧縮開始のロータ溝５１は吐出側端面で隣の雌ロータの溝とつながってしまい、雄ロータが回転して、雌ロータ側の溝とのつながりがきれるまで圧縮できず、このため吸入空気量が低下することになる。そこで、本実施例では、図１１の圧縮開始のタイミングにおいて、図１２に示すように吐出側端面で雄ロータ溝が閉じるための条件として、雄ロータの巻き角を２００°以下にしている。
【００３２】
図３は、吐出側軸受４も吸入空気で冷却するようにした本発明の第２実施例を示すもので、本実施例では圧縮機ケーシング３の外側に支持部材２５を介してダクト２２を設けた構造としている。ダクト２２の圧縮機吸入側端部は閉端部２３としており、圧縮機の吐出側軸受ハウジング５９付近にダクト吸入ポート２９を設けている。なお、ダクト吸入ポートの先端部には吸入フランジ２４を設けており、吸入フィルタや消音器と接続が可能に構成されている。また、圧縮機ケーシング３とダクト２２の間には空間が形成されており、ダクト吸入ポート２９から吸入した空気が吐出側軸受ハウジング５９を冷却した後、更に吸入側軸受ハウジング１６の周囲の吸入流路５３を通って、吸入空気が圧縮機に吸入されるようにし、これにより吸入側軸受５も冷却可能な構成としている。更に、Ｓケーシング９の吸入側軸受ハウジング１６の周囲には、図１に示す吸入管１０の代わりに吸入空気が滑らかに吸入流路５３に入るように吸入ガイド２６が設けられている。
【００３３】
次に、吸入空気による軸受の冷却効果を図９を用いて説明する。図９は、横軸に雄ロータ回転数をとり、縦軸には図１に示す吸入ポート構造における吸入側軸受５の外輪温度の上昇（吸入空気との温度差）を示す。この図から、雄ロータ回転数を高くすると、本来発熱量が増加して軸受外輪温度（空気との温度差）は増加するはずであるが、吸入空気速度も増加するため冷却効果が増大し、軸受外輪温度が低下する。従って、吐出側軸受４についてもハウジングの周囲を吸入空気で冷却すれば軸受を効果的に冷却可能である。
【００３４】
図４は、吐出側軸受４を水冷構造にした本発明の第３実施例を示す。この実施例では、吐出側軸受４もグリース潤滑とし、軸受の冷却を水で行うため、圧縮機吐出側軸受ハウジング５９の外周部に水ジャケット３０を形成し、水ジャケット３０の吸水口３１から水を供給し、排水口３２から水を排水する。なお、本実施例において、圧縮機を駆動するモータが、図２に示すように水冷の場合には、モータの水冷ジャケット６４と軸受４の水ジャケット３０に流す冷却水の吸水、排水系統を一緒にすることも可能である。
【００３５】
図５は、吸入ダクトから水を噴霧し、吐出空気温度を下げて吐出側軸受４の温度上昇を抑えるようにした本発明の第４実施例で、燃料電池用空気圧縮機として好適なものである。本実施例では、吸入管１０に水噴霧ノズル３３を設け、吸入空気中に水を噴霧することにより、吸入され圧縮される空気が冷却されるようにしたもので、本実施例によれば吐出ポートから吐出される吐出空気温度を下げることができる。
【００３６】
圧縮機吐出空気温度による吐出側軸受４の温度への影響を図１０により説明する。図１０は、横軸に圧縮機吐出空気温度（吐出温度）をとり、縦軸に吐出側軸受４の外輪温度（周囲空気温度との温度差）を示す。図１０に示すように、吐出温度を下げると、軸受外輪温度も低下するのがわかる。
【００３７】
図６は、圧縮機から吐出される吐出空気の吐出温度を一定にコントロールするため、図５に示す水噴射式スクリュー圧縮機を採用した車載用燃料電池システムを示す図である。圧縮機３４で０．１５〜０．２ＭＰａに昇圧された吐出空気は、吐出空気配管６１を通り、圧縮機吐出空気冷却用のクーラ３９で設定温度まで冷却されたあと、燃料電池３６のカソード極へ供給される。一方、水素は高圧水素タンク３５から水素供給配管６２によりアノード極へ供給される。燃料電池３６では水素と酸素の反応により電気を発生し、発生した電気は車輪駆動用モータ３８へ、インバータ３７を介して供給され、車を駆動する。なお、モータの回転速度はインバータ３７により制御される。また、燃料電池で発生した水蒸気は水蒸気冷却用のクーラ３９´で冷却された後、水セパレータ４３に送られ、そこで水分を分離し、排気空気は放出される。なお、水セパレータの下部に回収された水はポンプ４５で昇圧され、電動弁４１を介して吸入管１０に設けた水噴霧ノズル３３から吸入管１０内へ噴霧されるように構成している。
【００３８】
なお、圧縮機の吐出空気温度は吐出圧が０．２ＭＰａの時、１４０〜１９０度に達する可能性がある。吐出空気温度が高すぎると、特に吐出側軸受４の温度が高くなる。現在、車両用として多く用いられている固体高分子型燃料電池は作動温度が８０〜１００℃なので、吐出空気温度を８０〜１００℃に下げる必要がある。図５、図６に示すように、水噴霧を行うことにより、吐出空気温度を８０〜１００℃に保つことができるから、燃料電池へ供給する圧縮空気を冷却するためのクーラ３９を不要にすることもできる。しかし、吐出空気温度を下げすぎても燃料電池の反応が低下するため、水噴霧量を吐出空気温度に応じて適正値にコントロールする必要がある。
【００３９】
図６において、圧縮機の吐出空気配管６１には温度センサ４０を設置しており、検出した吐出空気温度は制御装置４４に取り込まれる。また、水配管６３には電動弁４１を設けており、温度センサ４０の検出温度に応じて制御装置４４から電動弁４１を動作させて、水噴霧量をコントロールし、吐出空気温度を一定に保つように制御している。
【００４０】
図７は本発明の第５実施例を示すもので、この実施例は、低騒音化のために、圧縮機ケーシング３の外部に防音カバ４６を設けたものである。防音カバ４６としては、吸音及び遮音性に優れた部材を使用する。なお、本実施例では、防音カバ４６を、騒音を吸収する吸音材６５と吸音材を固定するベース材６６とで構成している。圧縮機の騒音の原因として、ロータ振動や吐出脈動による流体力でケーシング３が加振され、騒音が増幅する要因がある。そこで、ケーシング３から防音カバ４６に振動が伝播しないように、防音カバ４６は、弾性体の固定部材４７を介して、ケーシング３のフランジ部２７及びＳケーシング９のフランジ部に固定されている。
【００４１】
以上説明した本実施例によれば、吸入側と吐出側の軸受をグリース潤滑としているので、給油ポンプやオイルクーラ等の強制給油装置が不要となり、小型で低価格化を実現できる。また、グリースに高温での調度軟化が小さく、低音での損失トルクの少ないグリースを用いることにより、高速での軸受潤滑に対する信頼性を向上できる。さらに、吸入流路を、吸入側軸受ハウジング外周とケーシング内周の間に形成し、軸方向吸い込みとすることにより、吸入側軸受は吸入空気により冷却されるので、更に軸受の信頼性を向上できる。
【００４２】
また、ロータの歯形をロータ径に対して溝の深い歯形とし、圧縮室からの漏洩を小さくし、更に圧縮開始時に、圧縮室を形成する溝の吐出端部での閉じ込み遅れがない巻き角とすることにより、小形化できると共に、低吐出圧に対して高効率が得られる効果がある。
【００４３】
ケーシングの外部にダクトを設け、吸入空気で吐出側軸受ハウジングと吸入側軸受ハウジングの両方を冷却するようにすれば、更に軸受の信頼性を向上できる。また、ダクトに防音効果をもたせるようにすれば、吸入側及び吐出側軸受を吸入空気で冷却可能とする他に騒音低減効果も得られる。
【００４４】
また、吐出側軸受のハウジング外部にジャケットを設け、水冷却を行うことで吐出側の軸受に対する信頼性を更に向上可能である。
更に、吸入管内に水を噴霧するようにすることにより、吐出空気温度を下げることができ、これにより吐出側軸受の温度上昇を低減でき、また燃料電池の動作温度に前記水噴射をコントロールすることにより、燃料電池に供給される圧縮空気を冷却するためのクーラを不要にできる効果がある。
【００４５】
【発明の効果】
本発明によれば、ケーシング内面と吸入側軸受ハウジング外面との間に吸入流路を設けると共に、吸入側と吐出側の軸受の潤滑に、高温での調度軟化が小さく且つ低温でのトルクの小さいグリースを使用し、更に雄ロータ径を１としたとき、雌ロータ径を０．８８以上、雄ロータと雌ロータとの軸間距離を０．６９以下、雄ロータの長さを１．１以下に構成しているので、高効率で、軸受部への強制給油の必要もなく、小形化も可能なスクリュー圧縮機を得ることができる効果がある。
【００４６】
また、吐出側軸受ハウジング側のケーシング外側に取り付けられ、該ケーシング及びケーシングに設けられた吸入通路との間に隙間を形成するように配置され且つ前記吸入側軸受ハウジング側が閉じられたダクトを設け、該ダクトには、前記吐出側軸受ハウジング側に、ダクト内への吸入用開口部を有すると共に、該吸入用開口部の部分を除き密閉空間を形成するように構成することにより、吸入空気で吐出側軸受ハウジングと吸入側軸受ハウジングの両方を冷却することができ、軸受の信頼性を更に向上できる。
【００４７】
更に、吐出側軸受ハウジングの外周部に冷却水ジャケットを設けるようにしたり、或いはロータへの吸入空間又はロータ間に形成される圧縮空間に水を噴霧するための水噴霧用ノズルを設けて吐出空気温度を下げるようにすれば、吐出側の軸受に対する信頼性を更に向上できる。
また、ケーシングの外側に弾性材を介して取り付けた防音カバーや吸音効果をもたせたダクトを設けることにより、低騒音化を図ることのできるスクリュー圧縮機が得られる。
【図面の簡単な説明】
【図１】本発明のスクリュー圧縮機の第１実施例を示す縦断面図。
【図２】圧縮機とモータとを一体型に直結した例を示す本発明の実施例を示すスクリュー圧縮機の縦断面図。
【図３】本発明のスクリュー圧縮機の第２実施例を示す縦断面図。
【図４】本発明のスクリュー圧縮機の第３実施例を示す縦断面図。
【図５】本発明のスクリュー圧縮機の第４実施例を示す縦断面図。
【図６】図５に示す水噴射式スクリュー圧縮機を採用した車載用燃料電池システムを示す系統図。
【図７】本発明のスクリュー圧縮機の第５実施例を示す縦断面図。
【図８】本発明のスクリュー圧縮機に好適なロータ歯形の例を示すロータ部分の断面図。
【図９】雄ロータ回転数に対する吸入側軸受の外輪温度との関係を説明する線図。
【図１０】圧縮機吐出温度に対する吐出側軸受の外輪温度との関係を説明する線図。
【図１１】圧縮を開始するタイミング（時点）での雄ロータ溝及び雌ロータ溝の状態を吸入側から見た吸入側断面図。
【図１２】圧縮を開始した雄ロータ溝の吐出側端面位置での状態を説明する吐出側断面図。
【図１３】図１に示すスクリュー圧縮機における吸入流路の部分を示す側面図。
【符号の説明】
１…雄ロータ、２…雌ロータ、３…ケーシング、４…吐出側軸受、５…吸入側軸受、６…接触式シール、７…非接触式シール、８…軸受カバー、９…Ｓケーシング、１０…吸入管、１１…タイミングギヤカバ、１２…タイミングギヤ、１３…カップリング、１４…仕切板、１５…パージ穴、１６…吸入側軸受ハウジング、１７…モータアダプタ、１８…モータ、２２…ダクト、２３…閉端部、２４…吸入フランジ（吸入側開口部）、３０…水ジャケット、３３…水噴霧ノズル、３４…圧縮機、３５…水素タンク、３６…燃料電池、３７…インバータ、３８…車輪駆動用モータ、３９，３９´…クーラ、４０…温度センサ、４１…電動弁、４２…電動弁駆動ドライバ、４３…水セパレータ、４４…制御装置、４６…防音カバ、４８…雄ロータ径、４９…雌ロータ径、５０…軸間距離、５１…雄ロータ溝、５２…雌ロータ溝、５３…吸入流路、５４…リブ、５５…雌ロータ後進面歯先円半径、５６…雌ロータ前進面歯先円半径、５７…雄ロータ歯先放物線焦点距離、５８…雄ロータ歯先円半径、５９…吐出側軸受ハウジング、６３…水供給配管、６５…吸音材、６６…ベース材。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw compressor suitable for supplying a low pressure and a large air volume, and is particularly suitable as an air compressor used in an in-vehicle fuel cell.
[0002]
[Prior art]
Conventionally, fuel cells are a type of energy converter that generates electricity using a chemical reaction that combines hydrogen and oxygen, and the only gas that is exhausted is water vapor. In recent years, the development of fuel cell vehicles has been promoted rapidly because it is expected to be a next-generation energy that can be replaced by fuel.
[0003]
Hydrogen for fuel cells can be filled in a high-pressure tank and mounted in a car or taken out from methanol or the like with a reformer. On the other hand, oxygen is normally contained in the atmosphere, and the air is compressed and taken into the fuel cell to react the contained oxygen.
[0004]
Therefore, in order to improve the output of the fuel cell or to reduce the size thereof, it is necessary to increase the output per unit size. For this purpose, it is necessary to actively promote the reaction in which hydrogen and oxygen are combined, and in many cases, the air supplied is increased to an atmospheric pressure or higher in order to increase the supply amount of oxygen. However, even if the supply pressure is too high, air containing unreacted oxygen is discharged from the fuel cell while maintaining the pressure, so that energy loss increases. Therefore, the air supply pressure is currently set at a low pressure of 0.15 to 0.2 MPa in consideration of energy efficiency.
[0005]
In addition, a compressor for supplying air to a fuel cell used for in-vehicle use is particularly desired to be small, light, high performance and low noise. As for the tooth profile of the low-pressure screw rotor, a conventional high-pressure stage machine or low-pressure stage machine of a stationary oil-free screw compressor having a two-stage configuration with a discharge pressure of 0.7 MPa is used. A special rotor dedicated to a low pressure of 2 MPa was not used.
[0006]
As a method for lubricating the bearing, there is a screw type on-vehicle supercharger described in Patent Document 1. In this supercharger, the intake and discharge bearings of both the male and female rotors are forcedly lubricated from the outside using engine lubricating oil.
No consideration is given to the soundproof structure against noise.
[0007]
[Patent Document 1] JP-A-6-317172
[Problems to be solved by the invention]
For compressors for in-vehicle fuel cells, small size, light weight, high performance, and low noise are desired. Therefore, in order to achieve a small size and high performance, it is necessary to reduce the tooth profile of the rotor to a tooth profile suitable for low pressure (0.15 to 0.2 MPa). In addition, since the fuel cell vehicle is driven by a motor, the lubrication system that is essential in the engine (internal combustion engine) is eliminated. For this reason, in order to forcibly lubricate the bearings of the compressor, the compressor itself is supplied with oil and discharged. It was necessary to provide a lubrication system with a hydraulic pump for oiling. For this reason, there has been a drawback that the compressor becomes large and complicated. Furthermore, since the fuel cell vehicle is driven by a motor, the noise is lower than that of the engine vehicle, and the noise of the compressor becomes conspicuous. Therefore, it is desired to reduce the noise of the compressor.
[0008]
An object of the present invention is to obtain a screw compressor that is highly efficient and does not require forced oiling to a bearing portion, and can be miniaturized thereby.
Another object of the present invention is to obtain a screw compressor capable of improving the reliability of these bearings by effectively cooling the discharge-side bearing and the suction-side bearing.
Still another object of the present invention is to obtain a screw compressor capable of reducing noise.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and each of the rotors. A bearing for supporting the suction side and the discharge side, a suction side bearing housing provided in the casing for receiving the suction side bearing, and a discharge side bearing housing provided for the casing for receiving the discharge side bearing. In the screw compressor, a suction flow path that is provided between the casing inner surface and the suction side bearing housing outer surface and forms a part of the suction passage;
It is used for lubrication of the suction side and discharge side bearings and the seal mechanism provided in the respective shaft penetrations of the suction side bearing housing and the discharge side bearing housing, and the softening at high temperature is small and the torque at low temperature is reduced. When the male rotor diameter is 1, the female rotor diameter is 0.88 or more, the axial distance between the male rotor and the female rotor is 0.69 or less, and the length of the male rotor is 1 .1 or less.
[0010]
Here, the winding angle of the male rotor may be configured such that the discharge side end face of the male rotor groove at the compression start position on the suction side is cut off from the communication with the groove of the female rotor on the discharge side end face of the casing. .
[0011]
A second feature of the present invention is that a pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and suction of each of the rotors Screw compression provided with a bearing that supports the suction side and the discharge side, a suction side bearing housing that is provided in the casing and accommodates the suction side bearing, and a discharge side bearing housing that is provided in the casing and accommodates the discharge side bearing A suction passage provided between an inner surface of the casing and an outer surface of the suction side bearing housing, and formed in a shaft passage portion of each of the suction side bearing housing and the discharge side bearing housing. Used for lubrication of the suction side and discharge side bearings, and softening of softness at high temperature and low torque at low temperature A duct that is attached to the outside of the casing on the discharge-side bearing housing side, is disposed so as to form a gap between the casing and the suction passage provided in the casing, and is closed on the suction-side bearing housing side And the duct has a suction opening into the duct on the discharge-side bearing housing side, and is configured to form a sealed space except for the suction opening.
[0012]
The third feature of the present invention is that a pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and the suction of each of the rotors Screw compression provided with a bearing that supports the suction side and the discharge side, a suction side bearing housing that is provided in the casing and accommodates the suction side bearing, and a discharge side bearing housing that is provided in the casing and accommodates the discharge side bearing A suction passage provided between an inner surface of the casing and an outer surface of the suction side bearing housing, and formed in a shaft passage portion of each of the suction side bearing housing and the discharge side bearing housing. Used for lubrication of the suction side and discharge side bearings, and softening of softness at high temperature and low torque at low temperature Lies in comprising a lease, a cooling water jacket provided on an outer peripheral portion of the discharge-side bearing housing.
[0013]
According to a fourth aspect of the present invention, there are a pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and the suction of each of the rotors A screw compressor comprising: a bearing that supports a suction side and a discharge side; a suction side bearing housing that houses the suction side bearing; and a discharge side bearing housing that houses the discharge side bearing, wherein the casing inner surface and the suction side A suction passage provided between the outer surface of the bearing housing and forming a part of the suction passage; a seal mechanism provided in each shaft penetrating portion of the suction side bearing housing and the discharge side bearing housing; and the suction side; Grease used for lubrication of the bearing on the discharge side, small in softness at high temperature and low in torque at low temperature, and suction space to the rotor or the rotor In the provision of the nozzle for spraying water for spraying water into the compression space formed.
[0014]
Further, in the above screw compressor, a discharge air pipe for supplying compressed air that has been compressed and discharged to another part, a temperature sensor provided in the discharge air pipe for detecting a discharge temperature, and the water injection nozzle Based on a detection signal from the temperature sensor, a water spray pipe for supplying water to the water, a motor valve provided in the water jet pipe, a driver for driving the motor valve, and the temperature sensor And a control device that controls the motor-operated valve.
[0015]
Further, at least one of the surface of each rotor or the inner peripheral surface of the casing is plated with a corrosion-resistant metal or coated with a water-resistant resin, or the lobe portion and the casing having a tooth groove of the rotor are made of a corrosion-resistant metal or water-resistant It is even better to use a conductive resin.
[0016]
A fifth feature of the present invention is that a pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and suction of each of the rotors A screw compressor comprising: a bearing that supports a suction side and a discharge side; a suction side bearing housing that houses the suction side bearing; and a discharge side bearing housing that houses the discharge side bearing, wherein the casing inner surface and the suction side A suction passage provided between the outer surface of the bearing housing and forming a part of the suction passage, a seal mechanism provided in a shaft penetrating portion of the suction side bearing housing, and used for lubricating the bearing, at a high temperature. Grease with low softening and low torque at low temperature, and an elastic material so as to form a space between the casing and the outside of the casing Lies in and a soundproof cover was.
[0017]
Here, the soundproof cover is configured with a suction end closed, and a suction opening for guiding air to the compressor is provided in the soundproof cover in the vicinity of the housing portion of the discharge side bearing. It is preferable to attach to the casing on the discharge side bearing housing side so as to form a sealed space in the cover except for the opening.
[0018]
In the above, the screw compressor has three male rotor teeth and five female rotor teeth, and further has a maximum rotation speed of the male rotor of at least 16000 min. ^-1 In addition, the female rotor may be configured to be directly coupled by an inverter-driven high-frequency motor or the like.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In this embodiment, the rotor tooth profile is small and a tooth profile that can achieve high efficiency even at low discharge pressure, and the rotor bearing is suctioned and discharged on both sides for grease lubrication, thereby eliminating the need for forced oiling and reducing the size of the compressor. We are also trying to reduce noise.
[0020]
First, in order to make a small and high-performance rotor tooth profile, the theoretical suction volume is increased to reduce leakage. In order to increase the theoretical suction volume, the number of teeth is reduced and the rotor groove is deepened, and the blowhole area causing leakage between the grooves of the rotor is made as small as possible. Further, the tooth profile is such that the seal line length that forms the leakage passage from the compression chamber side to the suction chamber side can be made as small as possible, and the rotor winding angle is such that the rotor groove at the start of compression does not cause a delay in closing.
[0021]
In order to eliminate the forced lubrication means, all the lubrication of the bearing will be grease lubrication and a means for cooling the bearing will be provided. Furthermore, in order to reduce the noise, a contrivance such as providing a cover of a soundproof structure capable of blocking noise on the outer periphery of the casing is provided so that the vibration of the casing is not transmitted.
[0022]
Hereinafter, specific embodiments of the present invention will be described with reference to FIGS.
FIG. 1 shows a first embodiment of the present invention. A low-pressure and high-efficiency male rotor 1 and female rotor 2 are housed in a casing 3 in a state of being engaged with each other. The discharge-side shaft portion of each rotor is rotatably supported by the discharge-side bearing 4 in the discharge-side bearing housing 59, and each suction-side shaft portion is in the suction-side bearing housing 16 of the S casing 9 that forms a suction port. The suction side bearing 5 is rotatably supported. The discharge-side bearing 4 employs a combination angular bearing, and a contact seal (oil seal) 6 is disposed on the compression chamber side of the housing via a circular partition plate 14, and further on the compression chamber side. A purge hole 15 is provided, and a non-contact type seal (carbon seal) 7 is provided on the further rotor side.
[0023]
Similarly, a contact-type seal (oil seal) 6 is provided on the shaft end side of the discharge side shaft portion, and a timing gear 12 is provided at each of the tip ends thereof. It is configured to be rotatable by contact.
[0024]
Similar to the discharge-side shaft portion, the suction-side shaft portions of both rotors have a contact seal (oil seal) 6 interposed between the suction-side bearing 5 and the rotor forming the compression chamber via a circular partition plate 14. Is provided. The suction side shaft ends of both rotors are closed by a bearing cover 8, and both bearings are lubricated with grease enclosed in the bearing housing. Here, since both sides of the discharge-side bearing 4 are sealed with contact-type seals 6, the bearing can be lubricated without leakage of grease. Also, the suction-side bearing 5 is also sealed with a contact seal 6 and the other is closed with a bearing cover 8, so that no grease leaks.
[0025]
The air compressor for fuel cells has a maximum speed of 16000 rpm for the male rotor, and the temperature rise of grease and bearings is severe.・ Use grease suitable for high temperatures. As shown in FIG. 13, the suction-side bearing housing 16 is cooled by air sucked from an axial suction passage 53 formed between the inside of the S casing 9 and the bearing housing 16. The intake air from the intake passage 53 is filled (sucked) into the rotor groove. The suction-side bearing housing 16 is provided with reinforcing ribs 54 in the suction passage 53 on the male and female rotor sides, respectively, and the mounting direction of the ribs 54 is 45 degrees above the center line of the rotor shaft. The gas pressure by compression is adjusted to the direction in which it acts on the rotor. The compression chamber side (inner end surface) of the lower part of the rotor of the S casing 9 forms an end surface for sealing the suction side end surface of the rotor groove when compression starts.
[0026]
Returning to FIG. 1, a suction pipe 10 connected to a suction filter and a silencer (not shown) is connected to the S casing 9 forming the suction port. The timing gear 12 provided at the discharge-side shaft end of the rotor is sealed with a timing gear cover 11, and the oil charged in the lower portion of the timing gear cover 11 is splashed with the timing gear 12 to be lubricated. . Further, the discharge-side shaft end portion of the female rotor passes through the timing gear cover 11 and is provided with a coupling 13 for connection to the motor. A contact-type seal (oil seal) 6 is also provided in the shaft through portion of the timing gear cover 11 so that the filled oil does not leak.
[0027]
FIG. 2 shows an embodiment in which a compressor similar to the compressor shown in FIG. 1 and a high-speed motor are directly connected. As shown in FIG. 2, the discharge side shaft of the female rotor 2 is lengthened to fit the motor rotor 19, and a motor casing 60 to which the stator 20 of the motor is fixed is attached to the casing of the compressor via the motor adapter 17. It has become. In this embodiment, the female rotor is driven, and the reason will be described below. In this embodiment, the number of teeth of the male rotor is 3 and the number of teeth of the female rotor is 5 as the tooth profile for low discharge pressure, and the rotational speed of the male rotor is 16000 min. ^-1 (16000 rpm) must be reached. Maximum speed of male rotor is 16000 min ^-1 In this case, the maximum number of rotations of the female rotor is 9600 min. ^-1 Therefore, in this embodiment, the maximum rotational speed is 10,000 min by driving the female rotor. ^-1 It can be directly connected by a motor of a certain degree, and can be constituted by a cheaper motor.
Reference numeral 64 denotes a water cooling jacket formed on the motor casing 60 for cooling the motor. Note that an air-cooled motor can be used instead of employing the water-cooled type with the water-cooling jacket 64.
[0028]
A rotor tooth profile suitable for low discharge pressure will be described with reference to FIG. The rotor for low discharge pressure has a small pressure ratio between the rotor grooves in the compression process, so even if the number of teeth is reduced, the leakage between the rotor grooves due to the pressure difference does not increase, and the number of teeth can be reduced. It is. If the number of teeth is reduced, the width of the tooth groove in the circumferential direction of the rotor can be increased and the groove can be deepened, and there is an advantage that the tooth profile coefficient indicating the ratio of the groove area for sucking air to the rotor cross-sectional area can be increased. is there. That is, since the tooth gap coefficient of the rotor formed by the tooth profile can be increased by increasing the tooth profile coefficient, if leakage from the seal line that forms the leakage gap from the rotor groove during compression to the suction space is constant, The ratio of the leakage amount to the intake air amount can be reduced, and as a result, the performance can be improved.
[0029]
In this embodiment, as shown in FIG. 8, the number of teeth was 3 for males and 5 for females, and the ratio of the male rotor diameter 48 to the rotor distance 50 was made as large as possible to deepen the groove. However, the maximum value of the male rotor is the dimension at which the minimum required tooth thickness of the female rotor is obtained with respect to the female rotor diameter 49. Further, in order to minimize the length of the seal line that forms the leakage gap generated in the meshing portion of the rotor, the radius of the arc of the female rotor advancement surface tooth tip (advance surface tooth tip arc radius) 56 is made as large as possible so that the male rotor The focal length 57 of the parabola of the tooth tip was reduced, and the radius 58 of the arc connected to the parabola of the male rotor tooth tip was also reduced. Further, the radius of the arc of the reverse face tip of the female rotor that determines the blowhole area that causes leakage between the rotor grooves formed by the casing 3, the tooth surface of the male rotor, and the tooth face of the female rotor (the reverse face tip arc) Radius 55 was also made as small as possible. The tooth profile of the other part of the male and female rotors is a shape created by the arc and the parabola. Based on the above, the specific shape of the tooth profile that can make the groove volume as large as possible, the seal line length that forms the leakage gap as small as possible, and the blow hole area as small as possible is shown below in the dimension ratio. That is, based on the diameter of the male rotor, the female rotor diameter is 0.886 or more, the inter-axis distance is 0.686 or less, the female rotor forward surface tooth tip arc radius is 0.044 or more, the female rotor reverse surface tooth tip arc radius 0.017 or less, the male rotor tooth tip parabolic focal length is 0.080 or less, the male rotor tooth tip arc radius is 0.01 or less, and the ratio of the male rotor length to the male rotor diameter is 1. It is good to make it 06 or less.
[0030]
In addition, when the rotor meshes and starts compression on the suction side end face, the groove where the compression of the male rotor has started is connected to the suction groove on the adjacent female rotor side on the discharge side end face. As a condition for preventing the occurrence of "", the winding angle of the male rotor is set to 200 ° or less. The closing delay will be described with reference to FIGS. 11 and 12. FIG. 11 shows the state of the male rotor groove 51 and the female rotor groove 52 at the timing (time point) when compression is started as viewed from the suction side. The male rotor is compressed in the right direction in FIG. 11, and the female rotor is rotated in the left direction. The rotor groove is twisted in the left rotation direction for the male rotor and the right rotation direction for the female rotor as viewed from the suction side. Accordingly, FIG. 12 shows the state of the rotor groove at the discharge end face as viewed from the suction side. FIG. 12 shows a state at the discharge side end face position of the male rotor groove which has started compression. In the state of FIG. 12, the compression start groove 51 is sealed by the inner wall of the casing and is connected to the groove on the female rotor side. There is no configured.
[0031]
If the winding angle of the male rotor is large, the compression-starting rotor groove 51 is connected to the groove of the adjacent female rotor at the discharge side end face, and the male rotor is rotated to be disconnected from the female rotor side groove. Cannot be compressed until the intake air amount decreases. Therefore, in this embodiment, at the compression start timing in FIG. 11, the winding angle of the male rotor is set to 200 ° or less as a condition for closing the male rotor groove on the discharge side end face as shown in FIG.
[0032]
FIG. 3 shows a second embodiment of the present invention in which the discharge-side bearing 4 is also cooled by intake air. In this embodiment, a duct 22 is provided outside the compressor casing 3 via a support member 25. Structure. The compressor suction side end of the duct 22 is a closed end 23, and a duct suction port 29 is provided in the vicinity of the discharge side bearing housing 59 of the compressor. Note that a suction flange 24 is provided at the tip of the duct suction port so that it can be connected to a suction filter and a silencer. Further, a space is formed between the compressor casing 3 and the duct 22, and after the air sucked from the duct suction port 29 cools the discharge side bearing housing 59, the suction flow around the suction side bearing housing 16 is further increased. The intake air is sucked into the compressor through the passage 53, whereby the suction side bearing 5 can be cooled. Further, a suction guide 26 is provided around the suction side bearing housing 16 of the S casing 9 so that the suction air smoothly enters the suction flow path 53 instead of the suction pipe 10 shown in FIG.
[0033]
Next, the effect of cooling the bearing by the intake air will be described with reference to FIG. 9, the horizontal axis represents the male rotor rotation speed, and the vertical axis represents the increase in the outer ring temperature of the suction side bearing 5 in the suction port structure shown in FIG. 1 (temperature difference from the intake air). From this figure, when the male rotor speed is increased, the heat generation amount should increase and the bearing outer ring temperature (temperature difference from the air) should increase, but the cooling effect increases because the intake air speed also increases. The bearing outer ring temperature decreases. Therefore, if the periphery of the housing is also cooled by the intake air, the bearing can be effectively cooled.
[0034]
FIG. 4 shows a third embodiment of the present invention in which the discharge side bearing 4 has a water cooling structure. In this embodiment, since the discharge-side bearing 4 is also grease lubricated and the bearing is cooled with water, a water jacket 30 is formed on the outer periphery of the compressor discharge-side bearing housing 59, and water is discharged from the water inlet 31 of the water jacket 30. And the water is drained from the drain port 32. In this embodiment, when the motor that drives the compressor is water-cooled as shown in FIG. 2, the water-cooling jacket 64 of the motor and the water absorption and drainage system for the cooling water flowing through the water jacket 30 of the bearing 4 are combined. It is also possible to make it.
[0035]
FIG. 5 shows a fourth embodiment of the present invention in which water is sprayed from the suction duct and the discharge air temperature is lowered to suppress the temperature rise of the discharge side bearing 4, which is suitable as an air compressor for a fuel cell. is there. In the present embodiment, a water spray nozzle 33 is provided in the suction pipe 10, and water that is sucked and compressed is cooled by spraying water into the suction air. The temperature of the discharge air discharged from the port can be lowered.
[0036]
The influence of the compressor discharge air temperature on the temperature of the discharge side bearing 4 will be described with reference to FIG. In FIG. 10, the horizontal axis represents the compressor discharge air temperature (discharge temperature), and the vertical axis represents the outer ring temperature of the discharge side bearing 4 (temperature difference from the ambient air temperature). As shown in FIG. 10, when the discharge temperature is lowered, the bearing outer ring temperature is also lowered.
[0037]
FIG. 6 is a diagram showing an in-vehicle fuel cell system that employs the water injection screw compressor shown in FIG. 5 in order to control the discharge temperature of the discharge air discharged from the compressor to be constant. The discharge air whose pressure has been increased to 0.15 to 0.2 MPa by the compressor 34 passes through the discharge air pipe 61 and is cooled to a set temperature by the cooler 39 for cooling the compressor discharge air, and then the cathode electrode of the fuel cell 36. Supplied to. On the other hand, hydrogen is supplied from the high-pressure hydrogen tank 35 to the anode electrode through the hydrogen supply pipe 62. The fuel cell 36 generates electricity by the reaction of hydrogen and oxygen, and the generated electricity is supplied to a wheel driving motor 38 via an inverter 37 to drive the vehicle. The rotation speed of the motor is controlled by the inverter 37. Further, the water vapor generated in the fuel cell is cooled by a water vapor cooling cooler 39 'and then sent to the water separator 43, where water is separated and the exhaust air is released. The water collected in the lower part of the water separator is pressurized by the pump 45 and sprayed into the suction pipe 10 from the water spray nozzle 33 provided in the suction pipe 10 via the motor-operated valve 41.
[0038]
The discharge air temperature of the compressor may reach 140 to 190 degrees when the discharge pressure is 0.2 MPa. If the discharge air temperature is too high, the temperature of the discharge-side bearing 4 is particularly high. Currently, since the polymer electrolyte fuel cell that is widely used for vehicles has an operating temperature of 80 to 100 ° C, it is necessary to lower the discharge air temperature to 80 to 100 ° C. As shown in FIG. 5 and FIG. 6, by performing water spray, the discharge air temperature can be maintained at 80 to 100 ° C., thus eliminating the need for the cooler 39 for cooling the compressed air supplied to the fuel cell. You can also. However, since the reaction of the fuel cell is lowered even if the discharge air temperature is lowered too much, it is necessary to control the water spray amount to an appropriate value according to the discharge air temperature.
[0039]
In FIG. 6, a temperature sensor 40 is installed in the discharge air piping 61 of the compressor, and the detected discharge air temperature is taken into the control device 44. Further, the water pipe 63 is provided with an electric valve 41, and the electric valve 41 is operated from the control device 44 according to the temperature detected by the temperature sensor 40 to control the water spray amount and keep the discharge air temperature constant. So that it is controlled.
[0040]
FIG. 7 shows a fifth embodiment of the present invention. In this embodiment, a soundproof cover 46 is provided outside the compressor casing 3 to reduce noise. As the soundproof cover 46, a member excellent in sound absorption and sound insulation is used. In this embodiment, the soundproof cover 46 is composed of a sound absorbing material 65 that absorbs noise and a base material 66 that fixes the sound absorbing material. As a cause of compressor noise, there is a factor that the casing 3 is vibrated by fluid force due to rotor vibration or discharge pulsation, and noise is amplified. Therefore, the soundproof cover 46 is fixed to the flange portion 27 of the casing 3 and the flange portion of the S casing 9 via an elastic fixing member 47 so that vibration does not propagate from the casing 3 to the soundproof cover 46.
[0041]
According to the present embodiment described above, the bearings on the suction side and the discharge side are grease-lubricated, so that a forced oiling device such as an oil pump or an oil cooler is not required, and a small size and a low price can be realized. In addition, the use of grease with low softening at high temperatures and low loss torque at high temperatures can improve the reliability of bearing lubrication at high speed. Furthermore, the suction flow path is formed between the outer periphery of the suction side bearing housing and the inner periphery of the casing, and by suctioning in the axial direction, the suction side bearing is cooled by the intake air, so that the reliability of the bearing can be further improved. .
[0042]
Also, the rotor tooth profile is a deep tooth profile with respect to the rotor diameter to reduce leakage from the compression chamber, and at the start of compression, there is no delay in closing at the discharge end of the groove forming the compression chamber As a result, the size can be reduced and high efficiency can be obtained for a low discharge pressure.
[0043]
If a duct is provided outside the casing and both the discharge side bearing housing and the suction side bearing housing are cooled by the intake air, the reliability of the bearing can be further improved. If the duct is provided with a soundproofing effect, the suction side and discharge side bearings can be cooled by the intake air, and a noise reduction effect can be obtained.
[0044]
Further, by providing a jacket outside the housing of the discharge side bearing and performing water cooling, the reliability of the discharge side bearing can be further improved.
Furthermore, by spraying water into the suction pipe, the discharge air temperature can be lowered, thereby reducing the temperature rise of the discharge side bearing, and controlling the water injection to the operating temperature of the fuel cell. This has the effect of eliminating the need for a cooler for cooling the compressed air supplied to the fuel cell.
[0045]
【The invention's effect】
According to the present invention, the suction passage is provided between the inner surface of the casing and the outer surface of the suction side bearing housing, and the softening at high temperature is small and the torque at low temperature is small for lubricating the bearings on the suction side and the discharge side. When grease is used and the male rotor diameter is set to 1, the female rotor diameter is 0.88 or more, the axial distance between the male rotor and the female rotor is 0.69 or less, and the length of the male rotor is 1.1 or less. Therefore, there is an effect that it is possible to obtain a screw compressor that is highly efficient, does not require forced oil supply to the bearing portion, and can be downsized.
[0046]
In addition, a duct that is attached to the outer side of the casing on the discharge side bearing housing side, is disposed so as to form a gap between the casing and the suction passage provided in the casing, and is closed on the suction side bearing housing side, The duct has a suction opening into the duct on the discharge-side bearing housing side, and is configured to form a sealed space except for the suction opening, thereby discharging with intake air. Both the side bearing housing and the suction side bearing housing can be cooled, and the reliability of the bearing can be further improved.
[0047]
Further, a cooling water jacket is provided on the outer peripheral portion of the discharge-side bearing housing, or a water spray nozzle for spraying water in a suction space to the rotor or a compression space formed between the rotors is provided. If the temperature is lowered, the reliability of the discharge-side bearing can be further improved.
Further, by providing a soundproof cover attached to the outside of the casing via an elastic material and a duct having a sound absorbing effect, a screw compressor capable of reducing noise can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of a screw compressor according to the present invention.
FIG. 2 is a longitudinal sectional view of a screw compressor showing an embodiment of the present invention showing an example in which a compressor and a motor are directly connected in an integrated manner.
FIG. 3 is a longitudinal sectional view showing a second embodiment of the screw compressor of the present invention.
FIG. 4 is a longitudinal sectional view showing a third embodiment of the screw compressor of the present invention.
FIG. 5 is a longitudinal sectional view showing a fourth embodiment of the screw compressor of the present invention.
6 is a system diagram showing an in-vehicle fuel cell system that employs the water injection screw compressor shown in FIG. 5;
FIG. 7 is a longitudinal sectional view showing a fifth embodiment of the screw compressor of the present invention.
FIG. 8 is a cross-sectional view of a rotor portion showing an example of a rotor tooth profile suitable for the screw compressor of the present invention.
FIG. 9 is a diagram illustrating the relationship between the outer ring temperature of the suction side bearing and the male rotor rotational speed.
FIG. 10 is a diagram for explaining the relationship between the discharge temperature of the discharge-side bearing and the compressor discharge temperature.
FIG. 11 is a suction side cross-sectional view of the state of the male rotor groove and the female rotor groove at the timing (time point) at which compression is started, as viewed from the suction side.
FIG. 12 is a discharge side cross-sectional view illustrating a state at the discharge side end face position of the male rotor groove which has started compression.
13 is a side view showing a portion of a suction flow path in the screw compressor shown in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Male rotor, 2 ... Female rotor, 3 ... Casing, 4 ... Discharge-side bearing, 5 ... Inhalation-side bearing, 6 ... Contact-type seal, 7 ... Non-contact-type seal, 8 ... Bearing cover, 9 ... S casing, 10 DESCRIPTION OF SYMBOLS ... Suction pipe, 11 ... Timing gear cover, 12 ... Timing gear, 13 ... Coupling, 14 ... Partition plate, 15 ... Purge hole, 16 ... Suction side bearing housing, 17 ... Motor adapter, 18 ... Motor, 22 ... Duct, DESCRIPTION OF SYMBOLS 23 ... Closed end part, 24 ... Suction flange (suction side opening part), 30 ... Water jacket, 33 ... Water spray nozzle, 34 ... Compressor, 35 ... Hydrogen tank, 36 ... Fuel cell, 37 ... Inverter, 38 ... Wheel Drive motor, 39, 39 '... cooler, 40 ... temperature sensor, 41 ... motor operated valve, 42 ... motor driven valve driver, 43 ... water separator, 44 ... control device, 46 ... soundproof cover, 48 ... male rotor diameter 49 ... Female rotor diameter, 50 ... Distance between shafts, 51 ... Male rotor groove, 52 ... Female rotor groove, 53 ... Suction channel, 54 ... Rib, 55 ... Female rotor reverse surface tip radius, 56 ... Female rotor advance Surface tooth tip radius, 57: male rotor tooth tip parabolic focal length, 58: male rotor tooth tip circle radius, 59 ... discharge-side bearing housing, 63 ... water supply pipe, 65 ... sound absorbing material, 66 ... base material.

Claims

A pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and a bearing that supports the suction side and the discharge side of each rotor A screw compressor including a suction side bearing housing provided in the casing and containing the suction side bearing; and a discharge side bearing housing provided in the casing and containing the discharge side bearing;
A suction passage provided between the casing inner surface and the suction-side bearing housing outer surface and forming a part of the suction passage;
A seal mechanism provided in each of the through-shaft portions of the suction-side bearing housing and the discharge-side bearing housing;
It is used for lubrication of the suction side and discharge side bearings, and has a softening softness at high temperature and a small torque at low temperature, and
When the male rotor diameter is 1, the female rotor diameter is 0.88 or more, the axial distance between the male rotor and the female rotor is 0.69 or less, and the length of the male rotor is 1.1 or less. A featured screw compressor.

2. The winding angle of the male rotor according to claim 1, wherein the discharge side end surface of the male rotor groove at the compression start position on the suction side is configured to be an angle at which communication with the groove of the female rotor is cut off at the discharge side end surface of the casing. A screw compressor characterized by that.

A pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and a bearing that supports the suction side and the discharge side of each rotor A screw compressor including a suction side bearing housing provided in the casing and containing the suction side bearing; and a discharge side bearing housing provided in the casing and containing the discharge side bearing;
A suction passage provided between the casing inner surface and the suction-side bearing housing outer surface and forming a part of the suction passage;
A seal mechanism provided in each of the through-shaft portions of the suction-side bearing housing and the discharge-side bearing housing;
Used for lubrication of the suction side and discharge side bearings, grease with low softening at high temperature and low torque at low temperature;
A duct that is attached to the outside of the casing on the discharge side bearing housing side, is disposed so as to form a gap between the casing and a suction passage provided in the casing, and is closed on the suction side bearing housing side;
The duct has a suction opening into the duct on the discharge-side bearing housing side, and is configured to form a sealed space except for the suction opening. Compressor.

A pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and a bearing that supports the suction side and the discharge side of each rotor A screw compressor including a suction side bearing housing provided in the casing and containing the suction side bearing; and a discharge side bearing housing provided in the casing and containing the discharge side bearing;
A suction passage provided between the casing inner surface and the suction-side bearing housing outer surface and forming a part of the suction passage;
A seal mechanism provided in each of the through-shaft portions of the suction-side bearing housing and the discharge-side bearing housing;
Used for lubrication of the suction side and discharge side bearings, grease with low softening at high temperature and low torque at low temperature;
A screw compressor comprising: a cooling water jacket provided on an outer peripheral portion of the discharge side bearing housing.

A pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and a bearing that supports the suction side and the discharge side of each rotor A screw compressor including a suction side bearing housing that houses the suction side bearing, and a discharge side bearing housing that houses the discharge side bearing;
A suction passage provided between the casing inner surface and the suction-side bearing housing outer surface and forming a part of the suction passage;
A seal mechanism provided in each of the through-shaft portions of the suction-side bearing housing and the discharge-side bearing housing;
Used for lubrication of the suction side and discharge side bearings, grease with low softening at high temperature and low torque at low temperature;
A screw compressor comprising a water spray nozzle for spraying water into a suction space into the rotor or a compression space formed between the rotors.

In Claim 5, the discharge air piping for supplying the compressed air compressed and discharged with the screw compressor to other parts,
A temperature sensor provided in the discharge air pipe for detecting the discharge temperature;
A water spray pipe for supplying water to the water injection nozzle;
An electric valve provided in the water injection pipe;
A driver for driving the electric valve;
A screw compressor comprising: a control device that controls an electric valve of the water injection pipe based on a detection signal from the temperature sensor.

6. The screw compressor according to claim 5, wherein at least one of a surface of each rotor or an inner peripheral surface of the casing is plated with a corrosion-resistant metal or coated with a water-resistant resin.

6. The screw compressor according to claim 5, wherein the lobe portion and the casing having the tooth gap of the rotor are made of a corrosion-resistant metal or a water-resistant resin.

A pair of male and female rotors that mesh and rotate in a non-contact manner with a timing gear, a casing that houses these rotors and has a suction passage and a discharge passage, and a bearing that supports the suction side and the discharge side of each rotor A screw compressor including a suction side bearing housing that houses the suction side bearing, and a discharge side bearing housing that houses the discharge side bearing;
A suction passage provided between the casing inner surface and the suction-side bearing housing outer surface and forming a part of the suction passage;
A seal mechanism provided in the shaft through portion of the suction side bearing housing;
Grease used for lubrication of the bearing, with small softening at high temperature and low torque at low temperature;
A screw compressor, comprising: a soundproof cover attached via an elastic material so as to form a space between the casing and the outside of the casing.

The soundproof cover according to claim 9, wherein the suction side has a closed end, and a suction opening for guiding air to the compressor is provided in the soundproof cover in the vicinity of the housing portion of the discharge side bearing, A screw compressor, wherein the screw compressor is attached to a casing on a discharge side bearing housing side so as to form a sealed space in the cover except for an opening for suction.

The screw compressor according to any one of claims 1 to 10, wherein the number of teeth of the male rotor constituting the screw compressor is three and the number of teeth of the female rotor is five.

12. The screw compressor according to claim 11, wherein the maximum number of rotations of the male rotor is at least 16000 min ⁻¹ and the female rotor is driven directly by a motor.