JP3559893B2

JP3559893B2 - Airtightness inspection method

Info

Publication number: JP3559893B2
Application number: JP29643698A
Authority: JP
Inventors: 透晃松谷
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1998-10-19
Filing date: 1998-10-19
Publication date: 2004-09-02
Anticipated expiration: 2018-10-19
Also published as: JP2000121485A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車用エンジンに代表されるような構造物について水漏れ，油漏れチェック等のために行われる気密性検査方法に関する。
【０００２】
【従来の技術】
図１０に示すように、内部が複数の空間（ブロックもしくは室）Ｓ１〜Ｓ３に区画され且つ各区画Ｓ１〜Ｓ３が微細な通路Ａ１，Ａ２で相互に連通されたワークＷのリークテスト方法として、各区画Ｓ１〜Ｓ３ごとに空気圧力源５１に接続されるエアレギュレータ５２〜５４、圧力計５５〜５７および流量計５８〜６０等を独立して設け、各空間Ｓ１〜Ｓ３にエアレギュレータ５２〜５４で設定された所定圧力の圧縮空気を導入したときの流量を個別に測定し、その実測流量値を予め設定された基準値（しきい値）と比較して各空間Ｓ１〜Ｓ３の気密性の適否を個別に判定するようにしたものが知られている。
【０００３】
【発明が解決しようとする課題】
図１０の構造において、特定の空間での漏れ量（ここではワーク外側への漏れのみを問題としている）が比較的大きい不良発生時には、その漏れの発生した空間での流量が増加するだけでなく通路Ａ１もしくはＡ２をもって連通している他の空間の流量もまた増加することになるため、実際に漏れが発生している空間以外の空間までもが気密性不良と判定されてしまうことがあり、結果として真に気密性不良が発生している空間を正確に特定することができなくなって、その後の気密性不良改善のための補修作業に長時間を要する結果となって好ましくない。
【０００４】
また、各空間Ｓ１〜Ｓ３に導入すべき圧縮空気の圧力調整ばらつきにより実際の流量が変動することになるため、検査結果の信頼性向上に限界がある。
【０００５】
本発明は以上のような課題に着目してなされたもので、検査精度の向上を図りながら、特に内部が複数の空間に区画されているワークであっても漏れ欠陥の発生部位を的確に特定できるようにした気密性検査方法を提供しようとするものである。
【０００７】
【課題を解決するための手段】
請求項１に記載の発明は、内部が複数の空間に区画されているとともに隣接する空間同士がそれぞれ微細な連通路で相互に連通しているワークの気密性を検査する方法であって、各空間ごとに独立している圧縮空気導入系統をもってそれぞれの空間にその空間相互が圧力平衡するまで所定圧力の圧縮空気を導入し、その時の流量と圧力とを各空間ごとに個別に測定する工程と、各空間ごとに前記実測圧力値を実測流量値で除した値もしくはその逆数を漏れ抵抗値として算出した上、その漏れ抵抗値を予め設定されている基準値と比較して前記各空間の連通路以外の部分での気密性の良否を判定する工程と、前記圧力平衡状態で相互に隣接する二つの空間のうちいずれか一方を大気解放したときの他方の空間での流量と圧力とを測定する工程と、この大気解放時の実測圧力値を実測流量値で除した値もしくはその逆数を前記二つの空間同士を連通している連通路の通路抵抗値として算出するとともに、前記通路抵抗値と前記一方の空間の漏れ抵抗値との合成抵抗値を算出し、この合成抵抗値を予め設定されている基準値と比較して前記連通路の抵抗の適否を判定する工程とを含むことを特徴としている。
【０００８】
請求項２に記載の発明は、請求項１に記載の発明における通路抵抗値と前記一方の空間の漏れ抵抗値との合成抵抗値は、前記通路抵抗値から漏れ抵抗値を減じた値もしくはその値の逆数であることを特徴としている。
【０００９】
請求項３に記載の発明は、内部が三つの空間に区画されているとともに互いに隣接する第１，第２の空間同士および第２，第３の空間同士がそれぞれ微細な連通路で相互に連通しているワークの気密性を検査する方法であって、各空間ごとに独立している圧縮空気導入系統をもってそれぞれの空間にその空間相互が圧力平衡するまで所定圧力の圧縮空気を導入し、その時の流量と圧力とを各空間ごとに個別に測定する工程と、各空間ごとに前記実測圧力値を実測流量値で除した値もしくはその逆数を漏れ抵抗値として算出した上、その漏れ抵抗値を予め設定されている基準値と比較して前記各空間の連通路以外の部分での気密性の良否を判定する工程と、前記圧力平衡状態で第１の空間を大気解放したときの第２の空間での流量と圧力とを測定するとともに、同じく前記圧力平衡状態で第３の空間を大気解放したときの第２の空間での流量と圧力とを測定する工程と、この第１，第３の空間の大気解放時における第２の空間のそれぞれの実測圧力値を実測流量値で除した値もしくはその逆数を第１，第２の空間同士および第２，第３の空間同士を連通している各連通路の通路抵抗値として算出するとともに、該通路抵抗値と前記第１の空間の漏れ抵抗値との合成抵抗値、および該通路抵抗値と前記第３の空間の漏れ抵抗値との合成抵抗値を個別に算出し、これらの各合成抵抗値を合成抵抗値ごとに予め設定されている基準値と個別に比較して前記各連通路の抵抗の適否を判定する工程とを含むことを特徴としている。
【００１０】
請求項４に記載の発明は、請求項３に記載の発明における通路抵抗値と前記第１の空間の漏れ抵抗値との合成抵抗値、および該通路抵抗値と前記第３の空間の漏れ抵抗値との合成抵抗値は、前記通路抵抗値から該当する空間の漏れ抵抗値を減じた値もしくはその値の逆数であることを特徴としている。
【００１１】
請求項５に記載の発明は、請求項３または４に記載の発明における検査対象ワークが自動車用エンジンであって、第１の空間が吸排気管を含む燃焼室であり、第２の空間がカムカバー室およびクランク室であり、第３の空間がオイル通路であって、さらに、前記連通路がピストンリング隙間およびメインメタル部のオイル通路開口部であることを特徴としている。
【００１３】
したがって、請求項１，２に記載の発明では、内部が複数の空間に区画されているとともに隣接する空間同士が微細な連通路で相互に連通しているワークの気密性を検査するにあたり、各空間のうち連通路を除いた部分のいわゆる外漏れの有無を検査する工程と、上記の連通路が所定の流通抵抗を有しているか否かのいわゆる内漏れの有無を検査する工程との二工程とに分けて検査することを前提としている。
【００１４】
そして、いわゆる外漏れの有無の検査にあたっては、各空間ごとに独立している圧縮空気導入系統をもってそれぞれの空間にその空間相互が圧力平衡するまで所定圧力の圧縮空気を導するとともに、その時の流量と圧力とを各空間ごとに個別に測定し、各空間ごとに前記実測圧力値を実測流量値で除した値もしくはその逆数を漏れ抵抗値として算出した上、その漏れ抵抗値を予め設定されている基準値と比較して前記各空間の連通路以外の部分での気密性の良否を判定する。こうすることにより、漏れ欠陥の有無すなわち各空間ごとの気密性判定の基準となる漏れ抵抗値に圧縮空気導入時の圧力と流量との二つのパラメータが反映されているため、圧縮空気導入時の圧力調整ばらつきにより流量が変動したとしても判定結果はこれらの影響を受けにくいものとなり、各空間同士が相互に連通していたとしてもそれぞれの空間の気密性を個別に適否判定することができるとともに、気密性不良の空間を的確に特定できる。
【００１５】
一方、内漏れ検査時には、前記圧力平衡状態で相互に隣接する二つの空間のうちいずれか一方を大気解放したときの他方の空間での流量と圧力とを測定し、この大気解放時の実測圧力値を実測流量値で除した値もしくはその逆数を前記二つの空間同士を連通している連通路の通路抵抗値として算出するとともに、この通路抵抗値と前記一方の空間の漏れ抵抗値との合成抵抗値を算出し、この合成抵抗値を予め設定されている基準値と比較して前記連通路の抵抗の適否を判定する。こうすることにより、実質的に連通路の通路抵抗値が外漏れ検査時の漏れ抵抗値によって補正されるので、例えば先の外漏れ検査の段階で特定の空間に漏れが発生していたとしても、その外漏れの影響を受けることなく真に連通路の流通抵抗の適否を的確に判定できる。
【００１６】
請求項３，４に記載の発明では、内部が三つの空間に区画されているとともに互いに隣接する第１，第２の空間同士および第２，第３の空間同士がそれぞれ微細な連通路で相互に連通しているワークの気密性を検査するにあたり、請求項１に記載の発明と同様の手法を適用したものであって、いわゆる外漏れ検査は請求項１に記載の発明と全く同様である。
【００１７】
一方、内漏れ検査時には、前記圧力平衡状態で第１の空間を大気解放したときの第２の空間での流量と圧力とを測定するとともに、同じく前記圧力平衡状態で第３の空間を大気解放したときの第２の空間での流量と圧力とを測定する。そして、この第１，第３の空間の大気解放時における第２の空間のそれぞれの実測圧力値を実測流量値で除した値もしくはその逆数を第１，第２の空間同士および第２，第３の空間同士を連通している各連通路の通路抵抗値として算出する。その上で、該通路抵抗値と前記第１の空間の漏れ抵抗値との合成抵抗値、および該通路抵抗値と前記第３の空間の漏れ抵抗値との合成抵抗値を個別に算出し、これらの各合成抵抗値を合成抵抗値ごとに予め設定されている基準値と個別に比較して前記各連通路の抵抗の適否を判定する。これにより、請求項１，２に記載の発明と同様に、連通路の通路抵抗値が外漏れ検査時の漏れ抵抗値によって補正されるので、例えば先の外漏れ検査の段階で特定の空間に漏れが発生していたとしても、その外漏れの影響を受けることなく真に各連通路の流通抵抗の適否を的確に判定できる。
【００１８】
請求項５に記載の発明では、前記請求項３または４に記載の発明を自動車用エンジンの気密性検査に適用したものであって、前記第１の空間が吸排気管を含む燃焼室となり、第２の空間がカムカバー室およびクランク室となり、第３の空間がオイル通路となり、さらに、前記連通路がピストンリング隙間およびメインメタル部のオイル通路開口部に該当する。これにより、燃焼室やクランク室さらにはオイル通路が必要十分な気密性を有しているか否かが個別に判定され、同時にピストンリング隙間やメインメタル部のオイル通路開口部が適切な流通抵抗を有しているか否かが個別に判定される。これは、特にピストンリングの破損の有無やメインメタル部で開口しているオイル通路が閉塞されていないかどうか把握する上できわめて有効である。
【００２０】
【発明の効果】
請求項１，２に記載の発明によれば、内部が複数の空間に区画されながらそれらの空間が微細な連通路で相互に連通しているワークの気密性の検査にあたり、各空間のうち連通路以外の部分の気密性を個別に検査するいわゆる外漏れ検査と、上記各連通路の流通抵抗を検査するいわゆる内漏れ検査との二工程に分けて検査を行うことを前提としつつ、外漏れ検査時には請求項１に記載の発明と同様の手法により各空間ごとに漏れ抵抗値を算出して個別に適否判定を行う一方、いわゆる内漏れ検査時には各連通路ごとに通路抵抗値と漏れ抵抗値との合成抵抗値を算出して適否判定を行うようにしたことから、気密性の適否判定基準となる漏れ抵抗値には圧縮空気導入時の圧力と流量の二つのパラメータが反映されているので、判定結果への圧力調整ばらつきによる流量変動や他の空間での気密性不良の影響がなくなり、各空間ごとにその気密性の適否判定を正確に行うことができるほか、気密性不良と判定された場合に該当する空間を的確に特定できる効果がある。また、内漏れ検査時には、実質的に連通路の通路抵抗値が特定の空間の漏れ抵抗値によって補正されるので、特定の空間に気密性不良が発生していたとしてもその影響を受けることなく、真に連通路の流通抵抗の適否を正確に判定できる効果がある。
【００２１】
請求項３，４に記載の発明によれば、内部が三つの空間に区画されながらそれら三つの空間が微細な連通路で相互に連通しているワークの気密性の検査にあたり、各空間のいわゆる外漏れに関する気密性検査およびいわゆる内漏れ検査としての各連通路の検査時に、請求項１に記載の発明と同様の手法を適用したものであるから、各空間ごとの気密性の適否判定と気密性不良と判定された場合に該当する空間の特定とを正確且つ的確に行えるほか、内漏れ検査時には、実質的に連通路の通路抵抗値が特定の空間の漏れ抵抗値によって補正されるので、特定の空間に気密性不良が発生していたとしてもその影響を受けることなく、真に連通路の流通抵抗の適否を正確に判定できる効果がある。
【００２２】
請求項５に記載の発明によれば、上記請求項３または４に記載の発明を自動車用エンジンの気密性検査に適用したものであるから、内部構造が複雑であっても、各空間ごとの気密性の適否判定と気密性不良と判定された場合に該当する空間の特とを正確且つ的確に行えるほか、各連通路の流通抵抗の適否を正確に判定できる効果がある。
【００２３】
【発明の実施の形態】
図１以下の図面は本発明の好ましい実施の形態を示す図で、自動車用エンジンの気密性を検査するためのリークテスタに適用した場合の例を示している。
【００２４】
図２に示すように、検査対象となるエンジンＥは、周知のように大きく分けて、吸排気管を含む第１の空間としての燃焼室１と、カムカバー室を含む第２の空間としてのクランク室２と、エンジンオイルが循環する第３の空間としてのオイル通路３とに区画されており、燃焼室１とクランク室２とは図外のピストンの周囲に装着されたピストンリング部の隙間４によって相互に連通しているとともに、クランク室２とオイル通路３とは図外のクランクシャフトを支えているメインメタル部に開口するオイル通路開口部５をもって相互に連通している。
【００２５】
エンジンＥ内の各空間である燃焼室１、クランク室２およびオイル通路３はそれぞれに独立した圧縮空気導入経路６，７，８を備えており、各圧縮空気導入経路６，７，８は空気圧調整ユニット９や減圧弁１０およびソレノイドバルブ１１等を介して空気圧力源１２に接続されている。そして、クランク室２系の圧縮空気導入経路７にはその上流側から順に減圧弁１３、流量計１４および圧力計１５等が介装されているのに対して、燃焼室１系及びオイル通路３系の圧縮空気導入経路６，８には、それぞれに減圧弁１６または１７、流量コントローラ１８または１９、圧力計２０または２１、およびソレノイドバルブ２２または２３が介装されている。さらに、上記各圧縮空気導入経路６，７，８は各圧力計１５，２０，２１の上流側で連通経路２４をもって相互に連通されており、この連通経路２４にはＰＩＤ制御装置２５を上位にもつ一対の差圧計２６，２７が介装されている。
【００２６】
上記の流量コントローラ１８，１９は流量計１４と同等の流量測定機能と可変絞りの機能と併せ持っていて、ＰＩＤ制御装置２５からの指示により絞りを調節することになる。すなわち、ＰＩＤ制御装置２５には差圧計２６または２７の出力が常時取り込まれていて、ＰＩＤ制御装置２５は上記差圧計２６または２７での差圧がなくなるように流量コントローラ１８，１９に対して絞り調節指令を出力する。そして、上記流量計１４の流量指示値や流量コントローラ１８，１９の流量指示値および各圧力計１５，２０，２１の圧力指示値はＡ／Ｄ変換装置２８を介してパーソナルコンピュータをもって構成された主制御装置２９に取り込まれるようになっている。また、主制御装置２９には、検査結果出力装置３０のほか、前記各ソレノイドバルブ１１，２２，２３を駆動するためのソレノイドバルブ駆動装置３１が接続されている。
【００２７】
このように構成されたリークテスタでは、図３，４，５に示すように、各空間であるところの燃焼室１、クランク室２およびオイル通路３のそれぞれについて連通路４，５を除いた部分に漏れ欠陥がないかどうか検査するいわゆる外漏れ検査と、クランク室２とオイル通路３とを相互に連通しているメインメタル部のオイル通路開口部５の通流抵抗が適切であるかどうか検査する第１内漏れ検査と、燃焼室１とクランク室２とを相互に連通しているピストンリング隙間４の通流抵抗が適切であるかどうか検査する第２内漏れ検査とに分けて検査が行われる。
【００２８】
上記外漏れ検査時には、図２，４に示すように全てのソレノイドバルブ１１，２２，２３がＯＮとされ、燃焼室１やクランク室２およびオイル通路３の全ての空間に一斉に圧縮空気が導入される。このとき、クランク室２への導入空気圧が基準とされて、この基準空気圧に対して燃焼室１への導入空気圧およびオイル通路３への導入空気圧の差圧がなくなるように制御され、結果として上記燃焼室１、クランク室２およびオイル通路３は図５に示すように互いに圧力平衡することになる。この圧力平衡状態で、図１に示すように各流量コントローラ１８，１９および流量計１４の流量指示値や各圧力計１５，２０，２１の圧力指示値が主制御装置２９に取り込まれる。ここでは、燃焼室１の実測圧力と実測流量とをＰ１，Ｑ１とし、同じくクランク室２のそれをＰ２，Ｑ２とし、同じくオイル通路３のそれをＰ３，Ｑ３とする（図１のステップＳ１）。
【００２９】
主制御装置２９では、上記各空間１，２，３の実測圧力値と実測流量値とをもとに演算を行って、実測圧力値を実測流量値で除した値もしくはその逆数を各空間の外漏れ抵抗値として算出する。例えば、燃焼室１の外漏れ抵抗値Ｒ１としてＲ１＝Ｐ１／Ｑ１を、クランク室の外漏れ抵抗値Ｒ２としてＲ２＝Ｐ２／Ｑ２を、オイル通路の外漏れ抵抗値Ｒ３としてＲ３＝Ｐ３／Ｑ３をそれぞれ算出する（ステップＳ２）。一方、主制御装置２９には上記燃焼室１等の各空間ごとの外漏れ抵抗値の基準値が所定の許容幅をもって予め設定されていることから、主制御装置２９では上記の各外漏れ抵抗値Ｒ１，Ｒ２，Ｒ３と該当する基準値とを個別に比較して、上記燃焼室１、クランク室２およびオイル通路３ごとの外漏れ欠陥の有無たる気密性の適否判定を行う（ステップＳ３，Ｓ４，Ｓ５）。
【００３０】
図６は上記クランク室２の外漏れ検査にあたり従来法による流量のみで適否判定を行なった場合の特性を、また図７は本発明の抵抗値にて適否判定を行なった場合の特性をそれぞれ示している。図６から明らかなように、従来法では測定ばらつきによって「気密性ＯＫ」の領域に「気密性ＮＧ」のワークが一部混在していて誤判定する可能性があるのに対して、図７では「気密性ＯＫ」領域と「気密性ＮＧ」領域とが明確に分離され、結果として誤判定がなくなって判定精度が向上することが理解できる。
【００３１】
こうして、外漏れ検査が終了すると、図２に示すようにオイル通路３の圧縮空気導入経路８のソレノイドバルブ２３がＯＦＦに切り換えられて、そのオイル通路３が大気解放される。オイル通路３が大気解放されると、クランク室２からオイル通路３側へメインメタル部のオイル通路開口部５を通して空気が流れ込むようになるとともに、燃焼室１とクランク室２との間では両者の差圧がなくなるように制御されることから、図５に示すように燃焼室１とクランク室２とはなおも圧力平衡状態を保つことになる。
【００３２】
そこで、主制御装置２９は、図８に示すように、上記オイル通路３の大気解放に伴うクランク室２の流量Ｑ２３と圧力Ｐ２３とを流量計１４と圧力計２０の指示値をもって取り込み（ステップＳ１１）、次式（１）の演算を行う（ステップＳ１２）。
【００３３】
Ｒ２３＝１／｛（Ｑ２３／Ｐ２３）−（Ｑ３／Ｐ３）｝‥‥‥（１）
すなわち、この実測流量値Ｑ２３を実測圧力値Ｐ２３で除した値もしくはその逆数を求める演算を行い、上記クランク２室とオイル通路３とを連通しているメインメタル部のオイル通路開口部５の通路抵抗値として例えばＱ２３／Ｐ２３として算出する。さらに、先の外漏れ検査時のオイル通路３の実測流量値Ｑ３と実測圧力値Ｐ３とから外漏れ抵抗値Ｑ３／Ｐ３を算出する。この場合、上記通路抵抗値としてＱ２３／Ｐ２３に代えてＰ２３／Ｑ２３を用いる場合には、オイル通路３の外漏れ抵抗値としてはＱ３／Ｐ３に代えてＰ３／Ｑ３をそのまま使用してもよい。さらに、上記通路抵抗値Ｑ２３／Ｐ２３と外漏れ抵抗値Ｑ３／Ｐ３との合成抵抗を求めるべく（Ｑ２３／Ｐ２３）−（Ｑ３／Ｐ３）の演算を行うとともにその逆数を求め、最終的にクランク室２とオイル通路３とを連通しているメインメタル部のオイル通路開口部５の真の通路抵抗値Ｒ２３としてＲ２３＝１／｛（Ｑ２３／Ｐ２３）−（Ｑ３／Ｐ３）｝を算出する。
【００３４】
そして、前記主制御装置２９には連通路であるところのメインメタル部のオイル通路開口部５に関する基準抵抗値が所定の許容幅をもって予め設定されていることから、主制御装置２９では上記の通路抵抗値Ｒ２３と基準値とを比較して（ステップＳ１３）、上記メインメタル部のオイル通路開口部５に関する通路抵抗値が適正であるかどうかその適否判定を行う（ステップＳ１４，１５）。以上をもって第１内漏れ検査が終了する。
【００３５】
こうして第１内漏れ検査が終了すると、図２，４に示すように上記とは逆にオイル通路３の圧縮空気導入経路８のソレノイドバルブ２３が再びＯＮに切り換えられるとともに、燃焼室１系の圧縮空気導入経路６のソレノイドバルブ２２がＯＦＦに切り換えられて、そのカムカムカバー室を含む燃焼室１が大気解放される。燃焼室が大気解放されると、クランク室２からその燃焼室１側へ連通路４を通して空気が流れ込むようになるとともに、図５に示すように、オイル通路３とクランク室２との間では両者の差圧がなくなるように制御されることから、オイル通路３とクランク室２とはなおも圧力平衡状態を保つことになる。
【００３６】
そこで、主制御装置２９は、図９に示すように、上記燃焼室１の大気解放に伴うクランク室２の流量Ｑ１２と圧力Ｐ１２とを流量計１４と圧力計１５の指示値をもって取り込み（ステップＳ２１）、次式（２）の演算を行う（ステップＳ２２）。
【００３７】
Ｒ１２＝１／｛（Ｑ１２／Ｐ１２）−（Ｑ１／Ｐ１）｝‥‥‥（２）
すなわち、この実測流量値Ｑ１２を実測圧力値Ｐ１２で除した値もしくはその逆数を求める演算を行い、上記クランク室２と燃焼室１とを連通している連通路としてのピストンリング隙間４の通路抵抗値として例えばＱ１２／Ｐ１２として算出する。さらに、先の外漏れ検査時の燃焼室１の実測流量値Ｑ１と実測圧力値Ｐ１とから外漏れ抵抗値Ｑ１／Ｐ１を算出する。この場合、上記通路抵抗値としてＱ１２／Ｐ１２に代えてＰ１２／Ｑ１２を用いる場合には、燃焼室１の外漏れ抵抗値としてはＱ１／Ｐ１に代えてＰ１／Ｑ１をそのまま使用してもよい。さらに、上記通路抵抗値Ｑ１２／Ｐ１２と外漏れ抵抗値Ｑ１／Ｐ１との合成抵抗を求めるべく（Ｑ１２／Ｐ１２）−（Ｑ１／Ｐ１）の演算を行うとともにその逆数を求め、最終的にクランク室２と燃焼室１とを連通しているピストンリング隙間４の真の通路抵抗値Ｒ１２としてＲ１２＝１／｛（Ｑ１２／Ｐ１２）−（Ｑ１／Ｐ１）｝を算出する。
【００３８】
そして、前記主制御装置２９には連通路であるところのピストンリング隙間４に関する基準抵抗値が所定の許容幅をもって予め設定されていることから、主制御装置２９では上記の通路抵抗値Ｒ１２と基準値とを比較して（ステップＳ２３）、上記ピストンリング隙間４に関する抵抗値が適正であるかどうかその適否判定を行う（ステップＳ２４，Ｓ２５）。以上をもって第２内漏れ検査が終了する。
【００３９】
こうして、一連の外漏れ検査、第１内漏れ検査および第２内漏れ検査が終了すると、図２，４に示すように全てのソレノイドバルブ１１，２２，２３がＯＦＦとなる一方、外漏れ検査、第１内漏れ検査および第２内漏れ検査のそれぞれの検査結果が出力装置３０から出力されて、その検査結果の表示と記録とが行われる。
【００４０】
ここで、上記の第１，第２内漏れ検査に際して、連通路であるところのメインメタル部のオイル通路開口部５もしくはピストンリング隙間４の通路抵抗値を、外漏れ検査時のオイル通路抵抗値もしくは燃焼室抵抗値をもって補正しているのは、外漏れが発生している状態で内漏れ検査に移行すると、流量測定時に実際には内漏れが発生していないにもかかわらずその外漏れの影響であたかも内漏れが発生しているかのような流量が検出されて誤判定する可能性があるためである。
【００４１】
すなわち、例えば燃焼室１系で外漏れが発生していると、燃焼室１を大気解放してクランク室２と燃焼室１との連通路であるピストンリング隙間４の通路抵抗を検査する際に、燃焼室１系の排気抵抗が小さくなることでクランク室２の流量が増加し、結果として連通路であるピストンリング隙間４が適正でないと誤判定してしまうことから、上記のように内漏れの抵抗を外漏れ抵抗値で補正することで、内漏れ検査時の判定精度が大幅に向上することになる。
【図面の簡単な説明】
【図１】図２の回路での外漏れ検査時の手順を示すフローチャート。
【図２】本発明の気密性検査方法が適用されるリークテスタの概略構成説明図。
【図３】気密性検査の全体の流れを示すフローチャート。
【図４】図２の回路での各ソレノイドバルブの切換タイミングを示すフローチャート。
【図５】気密性検査時の流量と圧力の変化を示す説明図。
【図６】従来法での気密性適否判定結果を示す特性図。
【図７】本発明での気密性適否判定結果を示す特性図。
【図８】図３の第１内漏れ検査時の詳細な手順を示すフローチャート。
【図９】図３の第２内漏れ検査時の詳細な手順を示すフローチャート。
【図１０】従来の気密性検査方法の一例を示す説明図。
【符号の説明】
１…燃焼室（第１の空間）
２…クランク室（第２の空間）
３…オイル通路（第３の空間）
４…ピストンリング隙間（連通路）
５…メインメタル部のオイル通路開口部（連通路）
６，７，８…圧縮空気導入経路
１４…流量計
１５…圧力計
１８，１９…流量コントローラ
２６，２７…差圧計
２０，２１…圧力計
２９…主制御装置
Ｅ…エンジン（検査対象ワーク）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an airtightness inspection method for checking a structure such as an automobile engine for water leaks and oil leaks.
[0002]
[Prior art]
As shown in FIG. 10, as a leak test method of a work W in which the inside is partitioned into a plurality of spaces (blocks or chambers) S1 to S3 and each of the partitions S1 to S3 communicates with each other through fine passages A1 and A2, Air regulators 52 to 54, pressure gauges 55 to 57, flow meters 58 to 60, and the like connected to the air pressure source 51 are provided independently for each of the sections S1 to S3, and the air regulators 52 to 54 are provided in the spaces S1 to S3. The flow rate when the compressed air of the predetermined pressure set in the step is introduced is individually measured, and the measured flow rate value is compared with a preset reference value (threshold value) to compare the airtightness of each of the spaces S1 to S3. It is known to determine the suitability individually.
[0003]
[Problems to be solved by the invention]
In the structure of FIG. 10, when a defect occurs in which the leakage amount in a specific space (here, only leakage to the outside of the work is a problem) is relatively large, not only does the flow rate in the space where the leakage occurs increase, but also Since the flow rate in the other space communicating with the passage A1 or A2 also increases, even a space other than the space where the leak actually occurs may be determined to have poor airtightness, As a result, it is not possible to accurately specify the space where the poor airtightness has occurred, and it takes a long time for the repair work to improve the poor airtightness, which is not preferable.
[0004]
In addition, since the actual flow rate fluctuates due to the pressure adjustment variation of the compressed air to be introduced into each of the spaces S1 to S3, there is a limit in improving the reliability of the inspection result.
[0005]
The present invention has been made in view of the above-described problems, and accurately identifies a portion where a leak defect has occurred even with a work having an interior partitioned into a plurality of spaces, while improving inspection accuracy. It is an object of the present invention to provide an airtightness inspection method.
[0007]
[Means for Solving the Problems]
ClaimItem 1The described invention is a method for inspecting the airtightness of a work in which the interior is partitioned into a plurality of spaces and adjacent spaces communicate with each other through fine communication paths, and the work is independent for each space. A step of introducing compressed air of a predetermined pressure into each space using a compressed air introducing system until the spaces are pressure-equilibrated with each other, and separately measuring a flow rate and a pressure at that time for each space; After calculating the value obtained by dividing the actually measured pressure value by the actually measured flow value or the reciprocal thereof as a leak resistance value, comparing the leak resistance value with a preset reference value, the part other than the communication passage of each space A step of determining whether airtightness is good or not, and a step of measuring a flow rate and a pressure in the other space when one of two spaces adjacent to each other in the pressure equilibrium state is released to the atmosphere, This atmosphere A value obtained by dividing the actually measured pressure value at the time of release by the actually measured flow value or the reciprocal thereof is calculated as the passage resistance value of the communication passage communicating the two spaces, and the passage resistance value and the leakage of the one space are calculated. Calculating a combined resistance value with the resistance value, and comparing the combined resistance value with a preset reference value to determine whether the resistance of the communication path is appropriate or not.
[0008]
ClaimItem 2The claimed invention is claimedItem 1The combined resistance value of the passage resistance value and the leakage resistance value of the one space in the described invention is a value obtained by subtracting the leakage resistance value from the passage resistance value or a reciprocal of the value.
[0009]
ClaimItem 3The invention described in the above is a work in which the interior is partitioned into three spaces and the first and second spaces adjacent to each other and the second and third spaces communicate with each other via fine communication paths. A method for inspecting the airtightness of a space, in which compressed air of a predetermined pressure is introduced into each space by using an independent compressed air introduction system for each space until the spaces are balanced with each other, and the flow rate and pressure at that time And the step of individually measuring each space, the value obtained by dividing the measured pressure value by the measured flow value or the reciprocal thereof for each space as a leak resistance value, the leak resistance value is set in advance Determining whether airtightness is good or bad in a portion other than the communication passage of each space by comparing with a reference value, and a flow rate in the second space when the first space is released to the atmosphere in the pressure equilibrium state. And measuring pressure Measuring the flow rate and the pressure in the second space when the third space is opened to the atmosphere in the pressure equilibrium state; and the second step when the first and third spaces are opened to the atmosphere. A value obtained by dividing the measured pressure value of each space by the measured flow rate value or the reciprocal thereof is calculated as a passage resistance value of each communication passage connecting the first and second spaces and the second and third spaces. Calculating a combined resistance value of the passage resistance value and the leakage resistance value of the first space, and a combined resistance value of the passage resistance value and the leakage resistance value of the third space. And individually comparing each combined resistance value with a reference value set in advance for each combined resistance value to determine whether or not the resistance of each communication path is appropriate.
[0010]
ClaimItem 4The claimed invention is claimedItem 3The combined resistance value of the passage resistance value and the leakage resistance value of the first space and the combined resistance value of the passage resistance value and the leakage resistance value of the third space in the described invention are calculated from the passage resistance value. It is characterized in that it is a value obtained by subtracting the leakage resistance value of the corresponding space or its reciprocal.
[0011]
ClaimItem 5The claimed invention is claimedItem 3 or 4The work to be inspected in the described invention is an automobile engine, the first space is a combustion chamber including an intake / exhaust pipe, the second space is a cam cover chamber and a crank chamber, and the third space is an oil passage. Further, the communication passage is characterized by a piston ring gap and an oil passage opening of a main metal portion.
[0013]
Therefore, in claims 1 and 2,In the described invention, when inspecting the airtightness of a work in which the interior is partitioned into a plurality of spaces and adjacent spaces communicate with each other via a fine communication passage, the communication passage is removed from each space. Inspection is divided into two steps: a step of inspecting the portion for the presence or absence of external leakage, and a step of inspecting whether or not the communication path has a predetermined flow resistance to determine the presence or absence of internal leakage. Is assumed.
[0014]
When testing for the presence or absence of so-called external leakage, a compressed air introduction system independent of each space is used to guide compressed air at a predetermined pressure into each space until the spaces are equilibrated with each other. And pressure separately for each spaceMeasure each spaceAfter calculating the value obtained by dividing the measured pressure value by the measured flow rate value or the reciprocal thereof as a leak resistance value, the leak resistance value is compared with a preset reference value, and a value other than the communication passage of each space is calculated. The quality of the airtightness of the part is determined. By doing so, the presence or absence of a leak defect, that is, the pressure and flow rate at the time of compressed air introduction are reflected in the leak resistance value, which is the reference for airtightness determination for each space, Even if the flow rate fluctuates due to pressure adjustment variations, the determination result is less likely to be affected by these, and even if the spaces are in communication with each other, the airtightness of each space can be individually determined as appropriate. The space with poor airtightness can be specified accurately.
[0015]
On the other hand, at the time of the internal leak inspection, when one of two spaces adjacent to each other in the pressure equilibrium state is released to the atmosphere, the flow rate and the pressure in the other space are measured. A value obtained by dividing the value by the actually measured flow rate value or the reciprocal thereof is calculated as a passage resistance value of the communication passage communicating the two spaces, and a synthesis of the passage resistance value and the leakage resistance value of the one space. A resistance value is calculated, and the combined resistance value is compared with a preset reference value to determine whether the resistance of the communication path is appropriate. By doing so, the passage resistance value of the communication path is substantially corrected by the leakage resistance value at the time of the external leakage inspection, so that, for example, even if leakage has occurred in a specific space at the stage of the external leakage inspection. Thus, it is possible to accurately determine whether the flow resistance of the communication passage is appropriate or not without being affected by the external leakage.
[0016]
ClaimItems 3 and 4In the described invention, a work in which the interior is partitioned into three spaces and the first and second spaces adjacent to each other and the second and third spaces communicate with each other via fine communication paths. To check the airtightness ofItem 1The same method as the described invention is applied.Item 1It is exactly the same as the described invention.
[0017]
On the other hand, at the time of the internal leak inspection, the flow rate and the pressure in the second space when the first space is opened to the atmosphere in the pressure equilibrium state are measured, and the third space is similarly opened to the atmosphere in the pressure equilibrium state. Then, the flow rate and the pressure in the second space are measured. Then, a value obtained by dividing the measured pressure value of each of the second spaces at the time of release of the first and third spaces to the atmosphere by the measured flow rate value or a reciprocal thereof is used for the first and second spaces and the second and third spaces. Calculated as the passage resistance value of each communication passage that connects the three spaces. Then, a combined resistance value of the passage resistance value and the leakage resistance value of the first space, and a combined resistance value of the passage resistance value and the leakage resistance value of the third space are individually calculated, Each of these combined resistance values is individually compared with a reference value set in advance for each combined resistance value to determine whether or not the resistance of each communication path is appropriate. As a result,Items 1 and 2Similarly to the described invention, since the passage resistance value of the communication passage is corrected by the leakage resistance value at the time of the external leakage inspection, for example, even if leakage has occurred in a specific space at the stage of the external leakage inspection, The suitability of the flow resistance of each communication path can be accurately determined without being affected by the external leakage.
[0018]
ClaimItem 5In the described invention, the claimItem 3 or 4The invention described above is applied to an airtightness inspection of an automobile engine, wherein the first space serves as a combustion chamber including an intake / exhaust pipe, the second space serves as a cam cover chamber and a crank chamber, and the third space serves as a third space. An oil passage is provided, and the communication passage corresponds to a piston ring gap and an oil passage opening of the main metal portion. As a result, it is individually determined whether the combustion chamber, the crank chamber, and the oil passage have a necessary and sufficient airtightness, and at the same time, the piston ring gap and the oil passage opening of the main metal portion provide an appropriate flow resistance. It is determined individually whether or not it has. This is extremely effective in determining whether the piston ring is damaged or not and whether the oil passage opening in the main metal portion is not blocked.
[0020]
【The invention's effect】
ClaimItems 1 and 2According to the invention described above, when inspecting the airtightness of a work in which the interior is partitioned into a plurality of spaces and the spaces communicate with each other through fine communication passages, the airtightness of a portion of each space other than the communication passages is inspected. It is premised that the inspection is performed in two steps, that is, a so-called outside leak inspection for individually inspecting the leakiness and a so-called inner leak inspection for checking the flow resistance of each communication passage. The leak resistance value is calculated for each space by the same method as the described invention, and the suitability is individually determined. On the other hand, at the time of a so-called internal leak test, the combined resistance value of the passage resistance value and the leak resistance value is determined for each communication path. Since the calculation is performed to determine the propriety, the leakage resistance value serving as the criterion for determining propriety of airtightness reflects two parameters of pressure and flow rate at the time of introducing compressed air. Adjustment variation The effect of flow rate fluctuations and poor airtightness in other spaces is eliminated, making it possible to accurately determine whether the airtightness is appropriate for each space. There is an effect that can be specified. Further, at the time of the internal leak inspection, the passage resistance value of the communication passage is substantially corrected by the leakage resistance value of the specific space, so that even if the airtightness failure occurs in the specific space, it is not affected. Thus, there is an effect that the suitability of the flow resistance of the communication path can be accurately determined.
[0021]
ClaimItems 3 and 4According to the described invention, when inspecting the airtightness of a work in which the interior is partitioned into three spaces and the three spaces communicate with each other through a fine communication path, an airtightness inspection for so-called external leakage of each space is performed. At the time of inspection of each communication passage as a so-called internal leak inspectionItem 1Since the same method as the described invention is applied, it is possible to accurately and accurately determine whether or not the airtightness of each space is appropriate and to specify a corresponding space when the airtightness is determined to be poor. At the time of inspection, since the passage resistance value of the communication passage is substantially corrected by the leakage resistance value of the specific space, even if poor airtightness has occurred in the specific space, it is not affected by the airtightness, and it is truly connected. There is an effect that it is possible to accurately determine whether the flow resistance of the passage is appropriate.
[0022]
ClaimItem 5According to the described invention, the above claimItem 3 or 4Since the described invention is applied to an airtightness inspection of an automobile engine, even if the internal structure is complicated, the appropriateness of the airtightness for each space and the space corresponding to the case where it is determined that the airtightness is poor are determined. In addition to being able to accurately and accurately perform the above, there is an effect that the suitability of the flow resistance of each communication passage can be accurately determined.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and the following drawings show preferred embodiments of the present invention, and show an example in which the present invention is applied to a leak tester for checking the airtightness of an automobile engine.
[0024]
As shown in FIG. 2, an engine E to be inspected is roughly divided into a combustion chamber 1 as a first space including an intake and exhaust pipe and a crank chamber as a second space including a cam cover chamber, as is well known. 2 and an oil passage 3 as a third space through which engine oil circulates. The combustion chamber 1 and the crank chamber 2 are separated by a gap 4 in a piston ring portion mounted around a piston (not shown). In addition to being in communication with each other, the crank chamber 2 and the oil passage 3 are in communication with each other through an oil passage opening 5 that opens to a main metal portion that supports a crankshaft (not shown).
[0025]
The combustion chamber 1, the crank chamber 2, and the oil passage 3, which are spaces in the engine E, have independent compressed air introduction paths 6, 7, and 8, respectively. It is connected to an air pressure source 12 via an adjustment unit 9, a pressure reducing valve 10, a solenoid valve 11, and the like. A pressure reducing valve 13, a flow meter 14, a pressure gauge 15, and the like are interposed in the compressed air introduction path 7 of the crank chamber 2 system from the upstream side in order from the upstream side. A pressure reducing valve 16 or 17, a flow controller 18 or 19, a pressure gauge 20 or 21, and a solenoid valve 22 or 23 are interposed in the compressed air introduction paths 6 and 8 of the system, respectively. Further, the compressed air introduction paths 6, 7, 8 are communicated with each other via a communication path 24 upstream of the pressure gauges 15, 20, 21. In the communication path 24, a PID control device 25 is placed at a higher level. A pair of differential pressure gauges 26 and 27 are interposed.
[0026]
The flow controllers 18 and 19 have a flow measurement function equivalent to that of the flow meter 14 and a variable throttle function, and adjust the throttle according to an instruction from the PID control device 25. That is, the output of the differential pressure gauge 26 or 27 is constantly taken into the PID control device 25, and the PID control device 25 restricts the flow controllers 18 and 19 so that the differential pressure at the differential pressure gauge 26 or 27 disappears. Outputs the adjustment command. The flow instruction value of the flow meter 14, the flow instruction value of the flow controllers 18 and 19, and the pressure instruction values of the pressure gauges 15, 20, and 21 are mainly transmitted from an A / D converter 28 to a main computer constituted by a personal computer. It is taken in by the control device 29. In addition to the inspection result output device 30, a solenoid valve driving device 31 for driving the solenoid valves 11, 22, 23 is connected to the main control device 29.
[0027]
In the leak tester thus configured, as shown in FIGS. 3, 4, and 5, each of the combustion chamber 1, the crank chamber 2, and the oil passage 3, which is a space, is provided at a portion other than the communication passages 4 and 5. A so-called outside leak test for checking for a leak defect, and a check for proper flow resistance of the oil passage opening 5 of the main metal portion that interconnects the crank chamber 2 and the oil passage 3 are performed. The inspection is performed in two parts: a first internal leakage inspection and a second internal leakage inspection for inspecting whether the flow resistance of the piston ring gap 4 interconnecting the combustion chamber 1 and the crank chamber 2 is appropriate. Is
[0028]
At the time of the above-mentioned external leak inspection, as shown in FIGS. 2 and 4, all the solenoid valves 11, 22, and 23 are turned on, and compressed air is simultaneously introduced into all the spaces of the combustion chamber 1, the crank chamber 2, and the oil passage 3. Is done. At this time, the air pressure introduced into the crank chamber 2 is used as a reference, and the control is performed so that the pressure difference between the air pressure introduced into the combustion chamber 1 and the air pressure introduced into the oil passage 3 is eliminated from the reference air pressure. The combustion chamber 1, the crank chamber 2, and the oil passage 3 are pressure-balanced with each other as shown in FIG. In this pressure equilibrium state, as shown in FIG. 1, the flow control values of the flow controllers 18 and 19 and the flow meter 14 and the pressure control values of the pressure gauges 15, 20 and 21 are taken into the main controller 29. Here, the measured pressure and measured flow rate of the combustion chamber 1 are P1 and Q1, those of the crank chamber 2 are P2 and Q2, and those of the oil passage 3 are P3 and Q3 (step S1 in FIG. 1). .
[0029]
The main controller 29 performs a calculation based on the measured pressure value and the measured flow rate value of each of the spaces 1, 2, 3, and calculates a value obtained by dividing the measured pressure value by the measured flow value or the reciprocal thereof, for each space. It is calculated as the external leakage resistance value. For example, R1 = P1 / Q1 as the external leakage resistance R1 of the combustion chamber 1, R2 = P2 / Q2 as the external leakage resistance R2 of the crank chamber, and R3 = P3 / Q3 as the external leakage resistance R3 of the oil passage. Each is calculated (step S2). On the other hand, since the reference value of the external leakage resistance value for each space such as the combustion chamber 1 is set in the main control device 29 in advance with a predetermined allowable width, the main control device 29 performs the above-described external leakage resistance value. The values R1, R2, and R3 are individually compared with corresponding reference values to determine whether or not there is an external leakage defect in each of the combustion chamber 1, the crank chamber 2, and the oil passage 3 (step S3). S4, S5).
[0030]
FIG. 6 shows the characteristics when the appropriateness is determined only by the flow rate according to the conventional method in the external leakage inspection of the crank chamber 2, and FIG. 7 shows the characteristics when the appropriateness is determined based on the resistance value of the present invention. ing. As is clear from FIG. 6, in the conventional method, the work of “airtight NG” is partially mixed in the area of “airtightness OK” due to the measurement variation, and there is a possibility of erroneous determination. In this case, it can be understood that the “hermetic OK” region and the “hermetic NG” region are clearly separated, and as a result, erroneous determination is eliminated and the determination accuracy is improved.
[0031]
When the external leakage inspection is completed in this way, as shown in FIG. 2, the solenoid valve 23 of the compressed air introduction passage 8 of the oil passage 3 is turned off, and the oil passage 3 is released to the atmosphere. When the oil passage 3 is released to the atmosphere, air flows from the crank chamber 2 to the oil passage 3 through the oil passage opening 5 of the main metal part, and between the combustion chamber 1 and the crank chamber 2 Since the control is performed so that the differential pressure is eliminated, the combustion chamber 1 and the crank chamber 2 still maintain a pressure equilibrium state as shown in FIG.
[0032]
Therefore, as shown in FIG. 8, the main controller 29 takes in the flow rate Q23 and the pressure P23 of the crank chamber 2 accompanying the release of the oil passage 3 to the atmosphere with the indicated values of the flow meter 14 and the pressure gauge 20 (step S11). ), The following equation (1) is calculated (step S12).
[0033]
R23 = 1 / {(Q23 / P23)-(Q3 / P3)} (1)
That is, a calculation is performed to obtain a value obtained by dividing the actually measured flow rate value Q23 by the actually measured pressure value P23 or a reciprocal thereof, and the passage of the oil passage opening 5 of the main metal portion communicating the crank 2 chamber with the oil passage 3 is performed. The resistance value is calculated as, for example, Q23 / P23. Further, an external leak resistance value Q3 / P3 is calculated from the actually measured flow value Q3 and the actually measured pressure value P3 of the oil passage 3 at the time of the above-mentioned external leak inspection. In this case, when P23 / Q23 is used instead of Q23 / P23 as the passage resistance value, P3 / Q3 may be used as it is instead of Q3 / P3 as the external leakage resistance value of the oil passage 3. Further, in order to obtain a combined resistance of the passage resistance value Q23 / P23 and the external leakage resistance value Q3 / P3, an operation of (Q23 / P23)-(Q3 / P3) is performed, and the reciprocal thereof is obtained. R23 = 1 / {(Q23 / P23)-(Q3 / P3)} is calculated as the true passage resistance value R23 of the oil passage opening 5 of the main metal part communicating the oil passage 2 with the oil passage 3.
[0034]
In the main control device 29, the reference resistance value for the oil passage opening 5 of the main metal portion, which is a communication passage, is set in advance with a predetermined allowable width. The resistance value R23 is compared with a reference value (step S13), and it is determined whether or not the passage resistance value of the main metal portion with respect to the oil passage opening 5 is appropriate (steps S14 and S15). With the above, the first internal leak inspection is completed.
[0035]
When the first internal leak test is completed in this manner, as shown in FIGS. 2 and 4, the solenoid valve 23 of the compressed air introduction path 8 of the oil passage 3 is turned on again, and the compression of the combustion chamber 1 system is reversed. The solenoid valve 22 in the air introduction path 6 is turned off, and the combustion chamber 1 including the cam cam cover chamber is released to the atmosphere. When the combustion chamber is released to the atmosphere, air flows from the crank chamber 2 to the combustion chamber 1 side through the communication passage 4 and, as shown in FIG. Is controlled so as to eliminate the differential pressure, the oil passage 3 and the crank chamber 2 still maintain a pressure equilibrium state.
[0036]
Therefore, as shown in FIG. 9, the main controller 29 takes in the flow rate Q12 and the pressure P12 of the crank chamber 2 accompanying the release of the combustion chamber 1 to the atmosphere with the indicated values of the flow meter 14 and the pressure gauge 15 (step S21). ), The following equation (2) is calculated (step S22).
[0037]
R12 = 1 / {(Q12 / P12)-(Q1 / P1)} (2)
That is, a calculation is performed to obtain a value obtained by dividing the actually measured flow rate value Q12 by the actually measured pressure value P12 or a reciprocal thereof, and to determine a passage resistance of the piston ring gap 4 as a communication passage connecting the crank chamber 2 and the combustion chamber 1. The value is calculated as, for example, Q12 / P12. Further, an external leakage resistance value Q1 / P1 is calculated from the actually measured flow value Q1 and the actually measured pressure value P1 of the combustion chamber 1 at the time of the above-mentioned external leak inspection. In this case, when P12 / Q12 is used instead of Q12 / P12 as the passage resistance value, P1 / Q1 may be used as it is instead of Q1 / P1 as the external leakage resistance value of the combustion chamber 1. Further, in order to obtain the combined resistance of the passage resistance value Q12 / P12 and the external leakage resistance value Q1 / P1, the calculation of (Q12 / P12)-(Q1 / P1) is performed, and the reciprocal thereof is calculated. R12 = 1 / {(Q12 / P12)-(Q1 / P1)} is calculated as a true passage resistance value R12 of the piston ring gap 4 communicating the combustion chamber 1 with the combustion chamber 1.
[0038]
Since the reference resistance value for the piston ring gap 4 which is a communication passage is set in the main control device 29 in advance with a predetermined allowable width, the main control device 29 sets the reference resistance value to the above-described passage resistance value R12. The value is compared with the value (step S23), and it is determined whether or not the resistance value of the piston ring gap 4 is appropriate (steps S24 and S25). With the above, the second internal leak inspection is completed.
[0039]
In this way, when a series of external leak inspection, first internal leak inspection, and second internal leak inspection are completed, all the solenoid valves 11, 22, 23 are turned off as shown in FIGS. The inspection results of the first internal leakage inspection and the second internal leakage inspection are output from the output device 30, and the inspection results are displayed and recorded.
[0040]
Here, at the time of the first and second inner leak inspections, the passage resistance value of the oil passage opening 5 of the main metal portion or the piston ring gap 4 which is a communication passage is determined by the oil passage resistance value at the time of the outer leakage inspection. Or, the reason for correcting using the combustion chamber resistance value is that if an internal leak is detected while an external leak is occurring, the external This is because there is a possibility that the flow rate is detected as if the internal leak has occurred, and an erroneous determination is made.
[0041]
That is, for example, when external leakage occurs in the combustion chamber 1 system, when the combustion chamber 1 is opened to the atmosphere and the passage resistance of the piston ring gap 4 which is a communication passage between the crank chamber 2 and the combustion chamber 1 is inspected. As the exhaust resistance of the combustion chamber 1 system decreases, the flow rate in the crank chamber 2 increases, and as a result, the piston ring gap 4 as a communication passage is erroneously determined to be inappropriate. By correcting the above resistance with the external leakage resistance value, the accuracy of the determination at the time of the internal leakage inspection is greatly improved.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a procedure at the time of external leakage inspection in the circuit of FIG. 2;
FIG. 2 is a schematic configuration explanatory view of a leak tester to which the airtightness inspection method of the present invention is applied.
FIG. 3 is a flowchart showing the overall flow of an airtightness inspection.
FIG. 4 is a flowchart showing switching timing of each solenoid valve in the circuit of FIG. 2;
FIG. 5 is an explanatory diagram showing changes in flow rate and pressure during an airtightness inspection.
FIG. 6 is a characteristic diagram showing a result of determining whether airtightness is appropriate according to a conventional method.
FIG. 7 is a characteristic diagram showing a result of judging whether airtightness is appropriate in the present invention.
FIG. 8 is a flowchart showing a detailed procedure at the time of a first internal leak test of FIG. 3;
FIG. 9 is a flowchart showing a detailed procedure at the time of a second internal leak test of FIG. 3;
FIG. 10 is an explanatory view showing an example of a conventional airtightness inspection method.
[Explanation of symbols]
1. Combustion chamber (first space)
2. Crank chamber (second space)
3. Oil passage (third space)
4: Piston ring gap (communication passage)
5. Oil passage opening (communication passage) in the main metal part
6, 7, 8 ... compressed air introduction path
14 ... Flow meter
15 ... Pressure gauge
18, 19 ... Flow controller
26, 27 ... differential pressure gauge
20, 21 ... pressure gauge
29 ... Main controller
E… Engine (work to be inspected)

Claims

A method for inspecting the airtightness of a work in which the interior is partitioned into a plurality of spaces and adjacent spaces communicate with each other through fine communication paths,
A step of introducing compressed air of a predetermined pressure into each space using a compressed air introduction system independent of each space until the spaces are pressure-balanced with each other, and individually measuring the flow rate and pressure at that time for each space. When,
A value obtained by dividing the measured pressure value by the measured flow rate value or the reciprocal thereof for each space is calculated as a leak resistance value, and the leak resistance value is compared with a preset reference value, and the communication path of each space is calculated. A step of determining whether the airtightness is good or bad in other parts,
A step of measuring the flow rate and the pressure in the other space when one of the two spaces adjacent to each other in the pressure equilibrium state is released to the atmosphere,
A value obtained by dividing the measured pressure value at the time of release to the atmosphere or a reciprocal thereof is calculated as a passage resistance value of a communication passage communicating the two spaces, and the passage resistance value and the one space are calculated. Calculating a combined resistance value with the leakage resistance value of the above, and comparing the combined resistance value with a preset reference value to determine the suitability of the resistance of the communication path;
An airtightness inspection method comprising:

The combined resistance value of the leakage resistance value of the flow resistance value and the one space, according to claim 1, characterized in that from the passage resistance is the reciprocal of the value or the value obtained by subtracting the leakage resistance Airtightness inspection method.

Inspection of the airtightness of the work, which is divided into three spaces and the first and second spaces adjacent to each other and the second and third spaces communicate with each other via minute communication paths. A way to
A step of introducing compressed air of a predetermined pressure into each space using a compressed air introduction system independent of each space until the spaces are pressure-balanced with each other, and individually measuring the flow rate and pressure at that time for each space. When,
A value obtained by dividing the measured pressure value by the measured flow rate value or the reciprocal thereof for each space is calculated as a leak resistance value, and the leak resistance value is compared with a preset reference value, and the communication path of each space is calculated. A step of determining whether the airtightness is good or bad in other parts,
The flow rate and the pressure in the second space when the first space is released to the atmosphere in the pressure equilibrium state are measured, and the second space when the third space is also released to the atmosphere in the pressure equilibrium state. Measuring the flow rate and pressure at
The value obtained by dividing the measured pressure value of each of the second spaces at the time of opening the first and third spaces to the atmosphere by the measured flow rate value or the reciprocal thereof is used for the first and second spaces and the second and third spaces. Calculated as a passage resistance value of each communication passage communicating the spaces, a combined resistance value of the passage resistance value and a leakage resistance value of the first space, and the passage resistance value and the third space. The combined resistance value is individually calculated with the leakage resistance value of each, and each of these combined resistance values is individually compared with a reference value preset for each combined resistance value to determine whether the resistance of each of the communication paths is appropriate. The process of
An airtightness inspection method comprising:

The combined resistance value of the passage resistance value and the leakage resistance value of the first space, and the combined resistance value of the passage resistance value and the leakage resistance value of the third space are determined from the passage resistance value. 4. The airtightness inspection method according to claim 3, wherein the leakage resistance value is a value obtained by subtracting the leakage resistance value or a reciprocal of the value.

The work to be inspected is an automobile engine, the first space is a combustion chamber including an intake / exhaust pipe, the second space is a cam cover chamber and a crank chamber, and the third space is an oil passage. The airtightness inspection method according to claim 3 , wherein the communication passage is a piston ring gap and an oil passage opening of a main metal portion.