JP3771167B2

JP3771167B2 - Air leak test method and apparatus

Info

Publication number: JP3771167B2
Application number: JP2001344408A
Authority: JP
Inventors: 僚福田
Original assignee: Fukuda Co Ltd
Current assignee: Fukuda Co Ltd
Priority date: 2001-11-09
Filing date: 2001-11-09
Publication date: 2006-04-26
Anticipated expiration: 2021-11-09
Also published as: JP2003149076A

Description

【０００１】
【発明の属する技術分野】
本発明は、密封容器の洩れを検査するのに好適なエアリークテスト装置に関する。
【０００２】
【従来の技術】
密封容器、特に小容積の密封容器であるワークの洩れを高精度で検出する差圧式エアリークテスト装置では、エア通路が、エア圧源に接続される共通通路と、この共通通路から分岐したワーク側分岐通路およびマスタ側分岐通路とを備えている。上記ワーク側分岐通路の下流端には、洩れの有無を検査すべきワークを収納するワークカプセルが接続され、上記マスタ側分岐通路の下流端には、漏れの無い良品ワーク（検査すべきワークと設計上等しい製品、以下同じ）をマスタ部材として収容するマスタカプセルが接続されている。上記共通通路には三方弁が設けられ、上記ワーク側，マスタ側分岐通路にはそれぞれ開閉弁が設けられている。この開閉弁の下流側においてワーク側，マスタ側の分岐通路間の差圧が差圧センサで検出されるようになっている。
【０００３】
制御部は、測定モードにおいて、上記一対の開閉弁の開き状態で三方弁を駆動することにより、ワークカプセルとマスタカプセルにエア圧源のテスト圧を供給し、次に開閉弁を閉じ、この状態での差圧センサの検出差圧を判別値と比較することにより、ワークの漏れの有無を判定する。
【０００４】
上記装置では、ワークに微小な傷があって、エアが時間をかけてワーク内に入り込む場合には、微小漏れとして検出することができるが、大きな傷があった場合には、漏れ無しと判断してしまう。上記テスト圧を供給した時に一気にワーク内にテスト圧のエアが入り込み、その後で開閉弁を閉じた状態では、ワーク側閉鎖系の圧力が低下せず、差圧が生じないからである。
【０００５】
そこで、微小漏れ（微小な傷に対応する漏れ）のみならず大きな漏れ（大きな傷に対応する漏れ）をも検出する装置が開発されている。特開平１０−６２２９６号公報に開示された装置では、ワーク側、マスタ側の分岐通路の上記開閉弁より下流側に、それぞれ容積変更手段が設けられている。この装置では、第１開閉弁を閉じて検出差圧を微小漏れ判別値と比較することにより微小漏れの有無を判定した後に、容積変更手段を駆動させてワーク側，マスタ側の分岐通路の容積を等量変更させる。この状態での差圧センサの検出差圧を大漏れ判別値と比較することにより、ワークの大漏れの有無を判定する。ワーク側の閉鎖系とマスタ側の閉鎖系の容積は、容積変更前も、容積変更後も等しいため、ワークに大漏れが無ければ、差圧センサで検出される差圧はゼロである。ワークに大漏れがあれば、容積変更前にワーク内に入り込んだテスト圧に起因して、ワーク側とマスタ側で差圧が生じる。
【０００６】
上記装置では、容積変更前のワーク側、マスタ側の閉鎖系の容積が、容積変更前も容積変更後も等しいことが求められる。しかし、製造誤差等により、これらワーク側とマスタ側の閉鎖系の容積を高精度で一致させるのが困難であり、漏れ判定の信頼性を損なう可能性があった。
【０００７】
特開平８−７５５９２号公報のエアリークテスト装置では、制御部は、エアリークテストに先だって、補正値設定モードを実行するようになっている。すなわち、ワークカプセルとマスタカプセルに良品ワークを収容した状態で、容積変更手段を駆動してワーク側，マスタ側の閉鎖系の容積を等量変更させた後に、差圧を検出し、この検出差圧を補正値として記憶する。そして、それ以後のエアリークテストにおいて、容積変更後の検出差圧からこの補正値を差し引くことにより、ワーク側閉鎖系，マスタ側閉鎖系の容積差に影響されない差圧値を算出し、この差圧値を大漏れ判別値と比較することにより、大漏れ判定の精度を上げようとしている。
【０００８】
【発明が解決しようとする課題】
しかし、上記特開平８−７５５９２号公報では、上記補正値を設定する他に、ワークに対応して上記大漏れ判別値をも設定しなければならず作業が煩雑であった。
【０００９】
【課題を解決するための手段】
本発明のエアリークテスト方法では、
（イ）エア圧源に接続される共通通路と、この共通通路から分岐したワーク側分岐通路およびマスタ側分岐通路と、
（ロ）上記ワーク側，マスタ側の分岐通路にそれぞれ設けられた一対の開閉弁と、
（ハ）上記ワーク側の分岐通路において、上記開閉弁の下流側に接続されたワークカプセルと、
（ニ）上記開閉弁の下流側においてワーク側，マスタ側の分岐通路間の差圧を検出する差圧センサと、
（ホ）上記ワーク側，マスタ側の分岐通路において上記開閉弁の下流側にそれぞれ設けられた一対の容積変更手段と、
を備えたエアリークテスト装置を用いて、測定モードと判別値設定モードを実行し、
上記測定モードでは、漏れを検査すべきワークをワークカプセルに収容した状態で、エア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に一対の開閉弁を閉じ、この状態での差圧センサの検出差圧と微小漏れ判別値とを比較することによりワークの微小漏れの有無を判定し、次に一対の容積変更手段を動作させることによりワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を大漏れ判別値と比較することによりワークの大漏れの有無を判定し、
上記判別値設定モードでは、
（ｉ）ワークカプセルに漏れの無い良品ワークを収容して閉じた状態でエア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に上記一対の開閉弁を閉じ、次に一対の容積変更手段を動作させることによりワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を第１差圧データとして得、
（ii）ワークカプセルに大漏れが生じる不良品ワークを収容して閉じた状態でエア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に上記一対の開閉弁を閉じ、次に一対の容積変更手段を動作させることによりワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を第２差圧データとして得、
（iii）上記第１差圧データと第２差圧データとの間の値を上記大漏れ判別値として設定することを特徴とする。
【００１０】
本発明方法によれば、判別値設定モードで得られた良品ワークの検出差圧（第１差圧データ）と、不良品ワークの検出差圧（第２差圧データ）には、ワーク側閉鎖系，マスタ側閉鎖系の容積誤差に起因した差圧分が含まれている。したがって、この第１，第２差圧データ間の値を大漏れ判別値として設定すれば、この大漏れ判別値にも上記容積誤差分に起因した差圧分が含まれることになる。測定モードでの検出差圧において容積誤差分に起因した差圧分は、この検出差圧を大漏れ検出と比較することにより相殺されるので、高精度の大漏れ検出を行うことができる。
また、上記のように大漏れ判別値は第１，第２差圧データの間の値として設定でき、設定作業を簡略化することができる。
【００１１】
好ましくは、上記マスタ側の分岐通路において上記開閉弁の下流側にマスタカプセルが接続されており、上記測定モードおよび判別値設定モードでは、このマスタカプセルに、共通の漏れの無い良品ワークをマスタ部材として収容する。これにより、マスタカプセルを設けることにより異なる種類のワークのリークテストにも簡単に対応することができる。また、マスタカプセルに収容されるマスタ部材として漏れの無い良品ワークを、測定モード，判別値設定モードに共通に用いるため、この良品ワークの外容積に誤差があっても、この誤差に起因する差圧分が測定モードでの検出差圧および大漏れ判別値の両者に含まれて相殺されるため、より高精度の大漏れ判定を行うことができる。
【００１２】
好ましくは、上記判別値設定モードでは、複数の良品ワークについて第１差圧データの平均値を得るととともに、複数の不良品ワークについて第２差圧データの平均値を得、これら平均値に基づき大漏れ判別値を設定する。これにより、この判別値設定モードで用いられる良品ワーク，不良品ワークの外容積の誤差の影響を排除して、大漏れ判別値を高精度で設定することができる。
【００１３】
より好ましくは、上記大漏れ判別値と第１差圧データの平均値との差と、大漏れ判別値と第２差圧データの平均値との差が、所定比率となるように大漏れ判別値を設定する。これにより、種々のワークの内容積に応じて大漏れ判別値を最適に設定することができる。
【００１４】
上記測定モードでワークの大漏れ無しと判定された場合の検出差圧を第１差圧データとし、ワークの大漏れ有りと判定された場合の検出差圧を第２差圧データとし、これら第１差圧データと第２差圧データに基づき、上記大漏れ判別値を更新する。これにより、ワーク側閉鎖系，マスタ側閉鎖系の容積の経時変化等を加味して大漏れ判別値を設定するので、より高精度の大漏れ判定を行うことができる。
【００１５】
さらに本発明の他の態様では、
（イ）エア圧源に接続される共通通路と、この共通通路から分岐したワーク側分岐通路およびマスタ側分岐通路と、
（ロ）上記ワーク側，マスタ側の分岐通路にそれぞれ設けられた一対の開閉弁と、（ハ）上記ワーク側の分岐通路において、上記開閉弁の下流側に接続されたワークカプセルと、
（ニ）上記開閉弁の下流側においてワーク側，マスタ側の分岐通路間の差圧を検出する差圧センサと、
（ホ）上記ワーク側，マスタ側の分岐通路において上記開閉弁の下流側にそれぞれ設けられた一対の容積変更手段と、
（ヘ）測定モードにおいて、漏れを検査すべきワークをワークカプセルに収容した状態で、エア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に一対の開閉弁を閉じ、この状態での差圧センサの検出差圧と微小漏れ判別値とを比較することによりワークの微小漏れの有無を判定し、次に一対の容積変更手段を動作することにより、ワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を大漏れ判別値と比較することにより、ワークの大漏れの有無を判定する制御部と、
を備えたエアリークテスト装置において、
上記制御部はさらに判別値設定モードを実行し、この判別値設定モードでは、
（ｉ）ワークカプセルに漏れの無い良品ワークを収容して閉じた状態で、エア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に上記一対の開閉弁を閉じ、次に一対の容積変更手段を駆動することによりワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を第１差圧データとして得、
（ii）ワークカプセルに大漏れが生じる不良品ワークを収容して閉じた状態で、エア圧源のテスト圧をワーク側，マスタ側の分岐通路に供給し、次に上記一対の開閉弁を閉じ、次に一対の容積変更手段を駆動することによりワーク側，マスタ側の閉鎖系の容積を等量変更し、この状態での差圧センサの検出差圧を第２差圧データとして得、
（iii）上記第１差圧データと第２差圧データとの間の値を上記大漏れ判別値として設定，記憶する。
【００１６】
本発明装置によれば、判別値設定モードで得られた良品ワークの検出差圧（第１差圧データ）と、不良品ワークの検出差圧（第２差圧データ）には、ワーク側閉鎖系，マスタ側閉鎖系の容積誤差に起因した差圧分が含まれている。したがって、この第１，第２差圧データ間の値を大漏れ判別値として設定すれば、この大漏れ判別値にも上記容積誤差分に起因した差圧分が含まれることになる。測定モードでの検出差圧において容積誤差分に起因した差圧分は、この検出差圧を大漏れ検出と比較することにより相殺されるので、高精度の大漏れ検出を行うことができる。
また、上記のように大漏れ判別値は第１，第２差圧データの間の値として設定でき、ワークに対応して設定せずに済むので作業を簡略化することができる。
【００１７】
本発明装置において、好ましくはさらに表示部を有し、上記制御部では、測定モードでの大漏れ検出の際の検出差圧から上記大漏れ判別値を差し引き、この値を表示部に表示する。作業者は、表示部に表示された差し引き値の極性に基づき、検査されるワークの大漏れの有無を確認することができる。このようにゼロ値を見掛けの大漏れ判別値として表示すれば、ワークの種類が変わっても見掛けの大漏れ判別値を変えなくて済む。
【００１８】
【発明の実施の形態】
以下、本発明のエアリークテスト装置を図面を参照して説明する。図１に示す第１実施形態のエアリークテスト装置は、エア通路１０を備えている。このエア通路１０は、共通通路１１と、この共通通路１１の下流端に接続されたワーク側分岐通路１２ａとマスタ側分岐通路１２ｂとを有している。共通通路１１の上流端には圧縮エア源１が接続されている。また共通通路１１には、上流側から順にレギュレータ２、三方弁３が設けられている。上記圧縮エア源１とレギュレータ２とで、エア圧源９が構成されている。上記三方弁３は、一対の分岐通路１２ａ，１２ｂをエア圧源９に連通させるテスト圧供給位置と、エア圧源９から遮断して大気に開放させる大気開放位置のいずれかを選択するものであり、オフ状態では大気開放位置にある。
【００１９】
上記分岐通路１２ａ，１２ｂには常開の第１開閉弁４ａ，４ｂがそれぞれ設けられ、下流端には同形状，同容積のワークカプセル５ａ，マスタカプセル５ｂがそれぞれ接続されている。カプセル５ａ、５ｂは開閉可能となっており、検査すべきワークＷ，良品ワークからなるマスタ部材Ｍをそれぞれ密封状態で収容できるようになっている。
【００２０】
第１開閉弁４ａ，４ｂの下流側の分岐通路１２ａ，１２ｂ間には、導入通路１５ａ、１５ｂを介して差圧センサ６が接続されている。
【００２１】
また、第１開閉弁４ａの下流側におけるワーク側分岐通路１２ａには、容積変更手段２０ａが設けられている。この容積変更手段２０ａは、分岐通路１２ａに一端が接続された補助通路２１ａと、この補助通路２１ａの中途部に設けられた常開の第２開閉弁２２ａと、その他端（下流端）に接続された所定容積のタンク２３ａとを有している。同様にして、第１開閉弁４ｂの下流側におけるマスタ側分岐通路１２ｂには、補助通路２１ｂ，第２開閉弁２２ｂ，タンク２３ｂからなる容積変更手段２０ｂが設けられている。なお、一対のタンク２３ａ，２３ｂは同容積であり、例えばマスタ部材Ｍを収容した状態のマスタカプセル５ｂとほぼ同程度となっている。
【００２２】
上記第２開閉弁２２ａが閉じた状態（容積変更動作前の状態）でのワーク側閉鎖系の容積（すなわち、第１開閉弁４ａの下流側の分岐通路１２ａの容積と、ワークカプセル５ａの容積と、第２開閉弁２２ａの上流側の補助通路２１ａの容積とを合計した容積）と、第２開閉弁２２ｂが閉じた状態（容積変更動作前の状態）でのマスタ側閉鎖系の容積（すなわち、第１開閉弁４ｂの下流側の分岐通路１２ｂの容積と、ワークカプセル５ｂの容積と、第２開閉弁２２ｂの上流側の補助通路２１ｂの容積とを合計した容積）とは、設計上互いに等しい。
【００２３】
また、第２開閉弁２２ａが開いた状態（容積変更動作後の状態）でのワーク側閉鎖系の容積（すなわち上記容積変更動作前のワーク側閉鎖系の容積に、第２開閉弁２２ａの下流側の補助通路２１ａの容積とタンク２３ａの容積を加えた容積）と、第２開閉弁２２ｂが開いた状態（容積変更動作後の状態）でのマスタ側閉鎖系の容積（すなわち上記容積変更動作前のマスタ側閉鎖系の容積に、第２開閉弁２２ｂの下流側の補助通路２１ｂの容積とタンク２３ｂの容積を加えた容積）とは、設計上互いに等しい。
【００２４】
さらに、エアリークテスト装置は、上述した各種の弁３，４ａ，４ｂ，２２ａ，２２ｂおよびカプセル５ａ，５ｂを制御するための制御部５０と、表示部６０とを備えている。
【００２５】
次に、上記構成をなすエアリークテスト装置の作用（エアリークテスト方法）を説明する。まず、制御部５０で通常行われる測定モードについて説明する。ワークカプセル５ａは検査すべきワークＷを収容した状態で閉じられ、マスタカプセル５ｂは良品ワークであるマスタ部材Ｍを収容した状態で閉じられる。第１開閉弁４ａ，４ｂが開いた状態で、第２開閉弁２２ａ，２２ｂを閉じた後、三方弁３をオンして、エア圧源９のテスト圧を分岐通路１２ａ，１２ｂに供給する。この後、第１開閉弁４ａ，４ｂを閉じて差圧センサ６の検出差圧を所定時間監視する。この検出差圧がゼロのまま変化しないか微小漏れ判別値以下の場合には、微小漏れが無いと判断する。検出差圧が微小漏れ判別値を越えた場合には、微小漏れ有りと判断する。
【００２６】
本実施形態での上記微小漏れ判定の詳細を説明する。本実施形態では、検出差圧は、ワーク側閉鎖系の圧力がマスタ側閉鎖系の圧力より低い時にマイナス出力となり、高い時にプラス出力となる。ワークＷに微小漏れがある場合には、検出差圧はマイナス出力となる。制御部５０では、この検出差圧を反転させ、この反転値から上記微小漏れ判別値（プラスの極性を有する）を差し引き、この差し引き値がプラスの場合には微小漏れ有りと判断し、マイナスの場合には上記微小漏れ無しと判断する。
上記差し引き値は表示部６０にも数値表示され、検査者はこの表示部６０で表示された数値の極性で、微小漏れの有無を確認することができる。
なお、本実施形態では、検査者の確認を容易にするために上記演算を行ったが、単に同じ極性を有する検出差圧と微小漏れ判別値を比較して微小漏れを判定してもよい。
【００２７】
微小漏れ無しと判断した場合、制御部５０は第２開閉弁２２ａ，２２ｂを開く。ワーク側の第２開閉弁２２ａが開くと、ワーク側閉鎖系の圧力がタンク２３ａへ逃げる。すなわち、ワーク側の閉鎖系は、第２開閉弁２２ａが閉じた状態の容積Ｖｗから、第２開閉弁２２ａの下流側の補助通路２１ａとタンク２３ａの容積分ΔＶｗだけが増大し、これに伴い、ワーク側閉鎖系の圧力は上記圧力Ｐｔから圧力Ｐｗまで低下する。同様に、マスタ側の第２開閉弁２２ｂが開くと、マスタ側の閉鎖系は、第２開閉弁２２ｂが閉じた状態の容積Ｖｍから、第２開閉弁２２ｂの下流側の補助通路２１ｂとタンク２３ｂの容積分ΔＶｍだけ容積が増大し、これに伴い、マスタ側閉鎖系の圧力も圧力Ｐｔから圧力Ｐｍまで低下する。
【００２８】
上記のようにワーク側閉鎖系とマスタ側閉鎖系の容積を等量変更した後、差圧センサ６での検出差圧を大漏れ判別値と比較して大漏れの有無を判断する。ワークＷに大漏れがある場合には、ワークＷの内部は容積変更前に既にテスト圧となっているため、このワークＷの内容積分だけワーク側閉鎖系の内容積が実質的に増え、容積変更後の圧力低下がマスタ側閉鎖系に比べて小さい。この差圧が差圧センサ６で検出されるのである。検出差圧が大漏れ判別値未満の場合には大漏れ無しと判断し、大漏れ判別値を越えた場合には、大漏れ有りと判断する。
【００２９】
本実施形態における上記大漏れ判定の詳細を説明する。ワークＷに大漏れがある場合には、本実施形態では検出差圧はプラスの出力となる。制御部５０では、この検出差圧から上記大漏れ判別値（プラスの極性を有する）を差し引き、この差し引き値がプラスの場合には大漏れ有りと判断し、マイナスの場合には上記大漏れ無しと判断する。この差し引き値は表示部６０にも表示され、検査者はこの表示部６０で表示された数値の極性で、微小漏れの有無を容易に確認することができる。
【００３０】
制御部５０は、上記漏れ判断を終了した後、第１開閉弁４ａ，４ｂを開くとともに三方弁３を大気開放位置にすることにより、この三方弁３の下流側のエア通路１０を全て大気開放にする。
微小漏れや大漏れが無いと判断した時には、表示部６０のランプ等を制御して良品表示を行い、漏れがある場合には不良品表示を行う。
【００３１】
前述したように、上記ワーク側閉鎖系とマスタ側閉鎖系の容積が設計通りに等しく、ワークＷに大漏れが無い場合には、容積変更後の差圧はゼロとなるはずである。しかし、ワークＷに大漏れが無くても、上記ワーク側閉鎖系とマスタ側閉鎖系の容積変更前後の容積が製造誤差等により互いに異なっていると、検出差圧がゼロにならない。そこで、本実施形態では、大漏れ判別値の設定の仕方を工夫することにより、この誤差を克服している。
【００３２】
以下、制御部５０で実施される大漏れ判別値を設定するためのモードについて詳述する。この判別値設定モードは上述した測定モードに先だって実行される。まず、多数の漏れの無い良品ワークと多数の大漏れが生じる不良品ワークを用意する。これらワークの良品，不良品の識別は予め行われている。
【００３３】
用意したワーク毎に判別値設定モードを実行する。詳述すると、ワークＷをワークカプセル５ａに収容し、良品ワークとしてのマスタ部材Ｍをマスタカプセル５ｂに収容した状態で、制御部５０は、これらカプセル５ａ，５ｂを閉じ、その後、測定モードと同様にして弁３、４ａ，４ｂ，２２ａ，２２ｂを動作させる。詳述すると、第１開閉弁４ａ，４ｂを開いたままで第２開閉弁２２ａ，２２ｂを閉じ、この後で三方弁３をオンすることにより、エア圧源９のテスト圧を、分岐通路１２ａ，１２ｂを介してカプセル５ａ，５ｂに供給する。次に、第１開閉弁４ａ，４ｂを閉じることにより、第１開閉弁４ａ，４ｂの下流側の分岐通路１２ａ，１２ｂおよびカプセル５ａ，５ｂを閉鎖系にする。次に、第２開閉弁２２ａ，２２ｂを開いて、ワーク側閉鎖系とマスタ側閉鎖系の容積を変更する。
【００３４】
上記容積変更後に、差圧センサ６の検出差圧を読み込む。検出差圧を読み込んだ後は、弁４ａ，４ｂ，２２ａ，２２ｂを開き、弁３を大気開放して、１回分の判別値設定モードを終了する。
【００３５】
上記判別値設定モードを、ワークカプセル５ａに収容されるワークＷとして、多数の良品ワークについて繰り返し行うことにより、図２に示すように良品ワークについての検出差圧（以下、第１差圧データと称す）の分布が得られる。また、上記判別値設定モードを、ワークＷとして多数の不良品ワークについて繰り返し行うことにより、不良品ワークについての検出差圧（以下、第２差圧データと称す）の分布も得られる。
【００３６】
制御部５０では、これら第１，第２差圧データの分布の中心値Ｄ１，Ｄ２（平均値）を演算する。そして、大漏れ判別値Ｄｘと第１基準値Ｄ１との差Ａと、大漏れ判別値Ｄｘと第１基準値Ｄ２との差Ｂが、特定の比率（本実施形態ではＡ＜Ｂ）となるように、大漏れ判別値Ｄｘを設定し記憶する。そして、この大漏れ判別値Ｄｘを以後の測定モードで用いる。
【００３７】
上記のように、良品ワークの検出差圧と不良品ワークの検出差圧との間に大漏れ判別値Ｄｘを設定したので、この大漏れ判別値Ｄｘは測定モードでの大漏れ検査時の検出差圧と同様に、ワーク側，マスタ側の閉鎖系の内容積の誤差により生じる差圧分を含んでおり、この検出差圧と大漏れ判別値Ｄｘとを比較することにより、上記容積誤差に起因した差圧分を相殺でき、この誤差に起因した大漏れ判定の精度低下を回避できる。また、大漏れ判別値を、判別値設定モードにより設定でき、ワークに対応して独自に設定する手間を省くことができる。
【００３８】
また、本実施形態では、複数の良品ワークの検出差圧の平均値Ｄ１と複数の不良品ワークの検出差圧の平均値Ｄ２から、大漏れ判別値Ｄｘを演算しているので、これらワークの外容積の誤差に左右されずに、高精度に大漏れ判別値Ｄｘを設定することができる。しかも、マスタ部材Ｍとなる良品ワークは、これら複数回の判別値設定モードにおいて共通であり、その後の測定モードにもそのまま用いられるため、この良品ワークの外容積の誤差に左右されずに、高精度に大漏れ判別値Ｄｘを設定することができるとともに、高精度に大漏れ判定を行うことができる。
【００３９】
また、本実施形態では、大漏れ判別値Ｄｘと第１基準値Ｄ１との差Ａと、大漏れ判別値Ｄｘと第１基準値Ｄ２との差Ｂが、特定の比率（本実施形態ではＡ＜Ｂ）となるように、大漏れ判別値Ｄｘを設定するので、検査すべきワークの種類が変更されても、その内容積に応じて最適の大漏れ判別値Ｄｘを設定することができる。
【００４０】
測定モードに戻って説明を追加するが、上述したように測定モードでは、検出差圧を大漏れ判別値Ｄｘで差し引いた値（以下、表示差圧値）が、プラスの場合を不良品と判断し、マイナスの場合を良品と判断する。すなわち、見かけ上の大漏れ判別値（表示判別値）をゼロとしている。このようにゼロ値を見掛けの大漏れ判別値として表示すれば、ワークの種類が変わっても見掛けの大漏れ判別値を変えなくて済む。
図３に示すように、良品の場合の表示差圧値の平均値と表示判別値の差は、判別値設定モードの場合の差Ａとほぼ等しくなるはずである。同様に、不良品の場合の表示差圧値の平均値と表示判別値の差は、判別値設定モードの場合の差Ｂとほぼ等しくなるはずである。
【００４１】
上記測定モードにおいて、表示差圧値がマイナスの場合に良品と判断したが、閾値「−Ｔｈ」を下回る場合には、マスタ側閉鎖系の故障と判断する。例えばマスタ部材が破損して大漏れが生じる場合には、この閾値「―Ｔｈ」よりさらにＢだけ下回った値の近傍に表示差圧値が表れるはずである。上記閾値「―Ｔｈ」は、例えば上記差Ａの２倍に設定される。
【００４２】
次に、本発明の第２実施形態について図２を参照しながら説明する。この実施形態において、第１実施形態に対応する構成には図中同番号を付してその説明を省略する。また、制御部５０，表示部６０は、図示を省略する。第２実施形態は、第１実施形態におけるマスタカプセル５ｂの代わりに、密閉容器３０がマスタ側分岐通路１２ｂの下流端に接続されており、マスタ側分岐通路１２ｂは第１開閉弁４ｂの下流側で閉塞されている。この密閉容器３０は、上記ワークカプセル５ａの内容積からワークＷの外容積を差し引いた値とほぼ等しい内容積を有している。その結果、マスタ側の閉鎖系の容積はワーク側の閉鎖系の容積とほぼ等しくなる。ここで、「ほぼ等しく」は、設計上等しい場合のみならず、外容積が異なる複数種のワークをテストすることを想定して、許容範囲内で若干の差異がある場合も含む。なお、上記密閉容器３０の代わりに、分岐通路１２ｂの配管を延長させて下流端を閉じてもよい。
【００４３】
上記第２実施形態において、制御部５０で実行される測定モードおよび判別値設定モードは、第１実施形態と同様であるので、説明を省略する。
【００４４】
上記第１，第２実施形態において、判別値設定モードで算出した判別値を、測定モードを繰り返す過程で、更新してもよい。例えば、測定モードで大漏れ無しの良品と判定される度にその検出差圧（第１差圧データ）を記憶し、大漏れ有りの不良品と判定される度にその検出差圧（第２差圧データ）を記憶し、これら第１，第２差圧データを判別値設定モードで演算した第１，第２差圧データまたは、前回の測定モードで更新した第１，第２差圧データに加味して、これら差圧データを更新し、これら差圧データに基づいて大漏れ判別値を更新する。この場合、移動平均，荷重平均，単純平均等で、上記差圧データを演算する。これにより、装置や環境の経時変化等に対応してより一層正確な大漏れ判別値を得ることができる。
【００４５】
上記第１，第２実施形態において、判別値設定モードでは、ワークの良品，不良品を予め認識せず、検出差圧の分布をワークの良品分布，不良品分布に識別し、これら分布に基づいて上記実施形態と同様にして大漏れ判別値を設定してもよい。この場合、判別値設定モードは測定モードと同様の制御を行ってもよい。また、始めから測定モードを多数回実行して、そのデータに基づき大漏れ判別値を設定してもよい。この場合、初期の測定モードが判別値設定モードとなる。
【００４６】
大漏れ判別値モードにおいて良品ワーク，不良品ワークについての差圧データは、分布を形成するほど多数でなくてもよい。例えば数個の良品ワーク，不良品について判別値設定モードを実行し、その検出差圧の単純平均から第１，第２の差圧データを得てもよい。さらに極端な例では、１個の良品ワーク，１個の不良品ワークについて判別値設定モードを実行して第１，第２の差圧データを得てもよい。データが少ない場合には、上述したように測定モードで大漏れ判別値を更新することにより、精度を高めることができる。
【００４７】
表示差圧値は、良品の場合にプラスとなり不良品の場合にマイナスとなってもよい。判別値設定モードにおいて、良品ワーク，不良品ワークの測定順序は逆でもよい。上記実施形態の容積変更手段は、容積を減少させ、分岐通路の圧力を高めるものでもよい。テスト圧は、負圧であってもよい。
【００４８】
【発明の効果】
以上説明したように本発明によれば、良品ワークと不良品ワークでの検出差圧から大漏れ判別値を得るようにしたので、ワーク側閉鎖系，マスタ側閉鎖系の容積誤差に拘わらず、高精度の大漏れ判定を行うことができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態をなすエアリークテスト装置の回路図である。
【図２】判別値設定モードを実行している際の検出差圧のデータ分布を示す図である。
【図３】測定モードを実行している際の検出差圧のデータ分布を示す図である。
【図４】本発明の第２の実施形態をなすエアリークテスト装置の回路図である。
【符号の説明】
４ａ，４ｂ第１開閉弁（開閉弁）
５ａワークカプセル
５ｂマスタカプセル
６差圧センサ
９エア圧源
１１共通通路
１２ａワーク側分岐通路
１２ｂマスタ側分岐通路
２０ａ，２０ｂ容積変更手段
５０制御部
６０表示部
Ｗワーク
Ｍマスタ部材（良品ワーク）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air leak test apparatus suitable for inspecting leakage of a sealed container.
[0002]
[Prior art]
In a differential pressure type air leak test device that detects leakage of a work, which is a sealed container, particularly a small-capacity sealed container, with high accuracy, the air passage has a common passage connected to an air pressure source and a work side branched from the common passage. A branch passage and a master side branch passage are provided. A work capsule for storing a work to be inspected for leakage is connected to the downstream end of the work side branch passage, and a non-defective workpiece (a work to be inspected) is connected to the downstream end of the master side branch passage. A master capsule that accommodates a product that is equal in design (hereinafter the same) as a master member is connected. The common passage is provided with a three-way valve, and the work-side and master-side branch passages are provided with on-off valves, respectively. The differential pressure between the branch passages on the work side and the master side is detected by a differential pressure sensor on the downstream side of the on-off valve.
[0003]
In the measurement mode, the control unit supplies the test pressure of the air pressure source to the work capsule and the master capsule by driving the three-way valve with the pair of open / close valves opened, and then closes the open / close valve. By comparing the detected differential pressure of the differential pressure sensor with a discriminant value, the presence or absence of workpiece leakage is determined.
[0004]
In the above device, if there is a minute scratch on the workpiece and air enters the workpiece over time, it can be detected as a minute leak, but if there is a large scratch, it is determined that there is no leakage. Resulting in. This is because when the test pressure is supplied, air of the test pressure enters the work at once, and when the on-off valve is closed thereafter, the pressure of the work side closing system does not decrease and no differential pressure is generated.
[0005]
Therefore, an apparatus for detecting not only a minute leak (a leak corresponding to a minute scratch) but also a large leak (a leak corresponding to a large scratch) has been developed. In the apparatus disclosed in Japanese Patent Laid-Open No. 10-62296, volume changing means are provided on the downstream side of the on-off valve of the branch passage on the work side and the master side. In this device, after the first on-off valve is closed and the detected differential pressure is compared with the minute leakage judgment value to determine the presence or absence of minute leakage, the volume changing means is driven to move the volume of the branch passage on the work side and the master side. The same amount. By comparing the detected differential pressure of the differential pressure sensor in this state with a large leak discrimination value, it is determined whether or not there is a large leak in the workpiece. Since the volume of the closed system on the workpiece side and the volume of the closed system on the master side are the same before and after the volume change, if there is no large leak in the workpiece, the differential pressure detected by the differential pressure sensor is zero. If there is a large leak in the workpiece, a differential pressure occurs between the workpiece and the master due to the test pressure that has entered the workpiece before the volume is changed.
[0006]
In the above apparatus, the volume of the closed system on the workpiece side and the master side before the volume change is required to be the same before and after the volume change. However, due to manufacturing errors and the like, it is difficult to make the volume of the closed system on the workpiece side and the master side coincide with each other with high accuracy, and there is a possibility that reliability of leakage determination is impaired.
[0007]
In the air leak test apparatus disclosed in JP-A-8-75592, the control unit executes a correction value setting mode prior to the air leak test. That is, in a state where non-defective workpieces are accommodated in the work capsule and the master capsule, the volume changing means is driven to change the volume of the closed system on the work side and the master side by an equal amount, and then the differential pressure is detected. The pressure is stored as a correction value. In the subsequent air leak test, by subtracting this correction value from the detected differential pressure after the volume change, a differential pressure value that is not affected by the volume difference between the work side closed system and the master side closed system is calculated. By comparing the value with the large leak determination value, the accuracy of the large leak determination is increased.
[0008]
[Problems to be solved by the invention]
However, in JP-A-8-75592, in addition to setting the correction value, it is necessary to set the large leak determination value corresponding to the work, and the work is complicated.
[0009]
[Means for Solving the Problems]
In the air leak test method of the present invention,
(A) a common passage connected to the air pressure source, a work side branch passage and a master side branch passage branched from the common passage,
(B) a pair of on-off valves respectively provided in the branch passage on the workpiece side and the master side;
(C) a work capsule connected to the downstream side of the on-off valve in the work side branch passage;
(D) a differential pressure sensor for detecting a differential pressure between the branch passage on the work side and the master side downstream of the on-off valve;
(E) a pair of volume changing means provided on the downstream side of the on-off valve in the work side and master side branch passages;
Execute measurement mode and discriminant value setting mode using an air leak test device equipped with
In the above measurement mode, with the work to be inspected for leakage contained in the work capsule, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, and this state By comparing the detected differential pressure of the differential pressure sensor with the micro leak discrimination value, the presence or absence of micro leak of the work is determined, and then the work side and master side closed systems are operated by operating a pair of volume changing means The presence or absence of a large leak in the workpiece is determined by comparing the detected differential pressure of the differential pressure sensor in this state with the large leak discrimination value.
In the discriminant value setting mode,
(I) In a state where a non-leakable work is contained in the work capsule and closed, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, By operating the pair of volume changing means, the volume of the closed system on the work side and the master side is changed by an equal amount, and the detected differential pressure of the differential pressure sensor in this state is obtained as the first differential pressure data,
(Ii) Supplying the test pressure of the air pressure source to the branch passage on the work side and the master side in a state where the defective work piece causing the large leak in the work capsule is accommodated and closed, and then closing the pair of on-off valves, Next, the volume of the closed system on the workpiece side and the master side is changed by an equal amount by operating a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as second differential pressure data,
(Iii) A value between the first differential pressure data and the second differential pressure data is set as the large leak determination value.
[0010]
According to the method of the present invention, the workpiece side closure is used for the detected differential pressure (first differential pressure data) of the non-defective workpiece obtained in the discriminant value setting mode and the detected differential pressure (second differential pressure data) of the defective workpiece. Differential pressure due to the volume error of the system and master side closed system is included. Therefore, if the value between the first and second differential pressure data is set as the large leak discriminating value, the large leak discriminating value also includes the differential pressure due to the volume error. In the detected differential pressure in the measurement mode, the differential pressure due to the volume error is offset by comparing the detected differential pressure with the large leak detection, so that highly accurate large leak detection can be performed.
Further, as described above, the large leak discrimination value can be set as a value between the first and second differential pressure data, and the setting work can be simplified.
[0011]
Preferably, a master capsule is connected to the downstream side of the on-off valve in the master side branch passage, and in the measurement mode and the discriminant value setting mode, a non-defective work having no common leak is connected to the master capsule as a master member. As housed. Thereby, it is possible to easily cope with leak tests of different types of works by providing the master capsule. In addition, since a non-defective workpiece that is not leaked as a master member accommodated in the master capsule is used in common in the measurement mode and discriminant value setting mode, even if there is an error in the external volume of this non-defective workpiece, the difference caused by this error Since the pressure component is included in both the detected differential pressure and the large leak determination value in the measurement mode and canceled out, it is possible to perform a large leak determination with higher accuracy.
[0012]
Preferably, in the discriminant value setting mode, an average value of the first differential pressure data is obtained for a plurality of non-defective workpieces, and an average value of the second differential pressure data is obtained for a plurality of defective workpieces. Set the large leak discrimination value. As a result, it is possible to set the large leak discriminating value with high accuracy by eliminating the influence of the error of the outer volume of the non-defective workpiece and defective product used in the discriminant value setting mode.
[0013]
More preferably, the large leak determination is performed such that the difference between the large leak determination value and the average value of the first differential pressure data and the difference between the large leak determination value and the average value of the second differential pressure data are a predetermined ratio. Set the value. Thereby, the large leak discriminating value can be optimally set according to the internal volume of various workpieces.
[0014]
In the above measurement mode, the detected differential pressure when it is determined that there is no major leakage of the workpiece is the first differential pressure data, and the detected differential pressure when it is determined that there is a large workpiece leak is the second differential pressure data. The large leak determination value is updated based on the first differential pressure data and the second differential pressure data. Thereby, since the large leak discriminant value is set in consideration of the time-dependent change in the volumes of the work side closed system and the master side closed system, it is possible to perform a large leak determination with higher accuracy.
[0015]
In yet another aspect of the invention,
(A) a common passage connected to the air pressure source, a work side branch passage and a master side branch passage branched from the common passage,
(B) a pair of on-off valves provided in the branch passage on the workpiece side and the master side, and (c) a work capsule connected to the downstream side of the on-off valve in the branch passage on the workpiece side,
(D) a differential pressure sensor for detecting a differential pressure between the branch passage on the work side and the master side downstream of the on-off valve;
(E) a pair of volume changing means provided on the downstream side of the on-off valve in the work side and master side branch passages;
(F) In the measurement mode, with the work to be inspected for leakage contained in the work capsule, supply the test pressure of the air pressure source to the branch passage on the work side and the master side, and then close the pair of on-off valves, In this state, the presence or absence of minute leakage of the workpiece is determined by comparing the detected differential pressure of the differential pressure sensor and the minute leakage determination value, and then the workpiece side and master side are operated by operating a pair of volume changing means. A control unit that determines the presence or absence of a large leak of the workpiece by changing the volume of the closed system in an equal amount, and comparing the detected differential pressure of the differential pressure sensor in this state with a large leak discrimination value
In an air leak test apparatus equipped with
The control unit further executes a discriminant value setting mode, and in this discriminant value setting mode,
(I) In a state where a non-leaked work piece is contained in the work capsule and closed, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, The volume of the closed system on the workpiece side and the master side is changed by an equal amount by driving a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as first differential pressure data,
(Ii) Supplying the test pressure of the air pressure source to the branch path on the work side and master side with the closed work piece containing a defective work that causes a large leak in the work capsule, and then closing the pair of on-off valves Then, the volume of the closed system on the work side and the master side is changed by an equal amount by driving a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as second differential pressure data,
(Iii) A value between the first differential pressure data and the second differential pressure data is set and stored as the large leak determination value.
[0016]
According to the apparatus of the present invention, the workpiece side closure is used for the detected differential pressure (first differential pressure data) of the non-defective workpiece obtained in the discrimination value setting mode and the detected differential pressure (second differential pressure data) of the defective workpiece. Differential pressure due to the volume error of the system and master side closed system is included. Therefore, if the value between the first and second differential pressure data is set as the large leak discriminating value, the large leak discriminating value also includes the differential pressure due to the volume error. In the detected differential pressure in the measurement mode, the differential pressure due to the volume error is offset by comparing the detected differential pressure with the large leak detection, so that highly accurate large leak detection can be performed.
Further, as described above, the large leak discrimination value can be set as a value between the first and second differential pressure data, and it is not necessary to set it corresponding to the work, so that the work can be simplified.
[0017]
The apparatus of the present invention preferably further includes a display unit, and the control unit subtracts the large leak determination value from the detected differential pressure when the large leak is detected in the measurement mode, and displays this value on the display unit. The operator can confirm whether there is a large leak of the workpiece to be inspected based on the polarity of the subtraction value displayed on the display unit. If the zero value is displayed as an apparent large leak determination value in this way, it is not necessary to change the apparent large leak determination value even if the type of workpiece changes.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The air leak test apparatus of the present invention will be described below with reference to the drawings. The air leak test apparatus according to the first embodiment shown in FIG. The air passage 10 includes a common passage 11, and a work side branch passage 12 a and a master side branch passage 12 b connected to the downstream end of the common passage 11. A compressed air source 1 is connected to the upstream end of the common passage 11. The common passage 11 is provided with a regulator 2 and a three-way valve 3 in order from the upstream side. The compressed air source 1 and the regulator 2 constitute an air pressure source 9. The three-way valve 3 selects either a test pressure supply position where the pair of branch passages 12a, 12b are communicated with the air pressure source 9, or an atmosphere release position where the air pressure source 9 is shut off and opened to the atmosphere. Yes, in the open state in the off state.
[0019]
The branch passages 12a and 12b are provided with first open / close valves 4a and 4b that are normally open, respectively, and work capsules 5a and master capsules 5b having the same shape and volume are connected to the downstream ends. The capsules 5a and 5b are openable and closable, and can accommodate the master member M made up of the workpiece W to be inspected and the non-defective workpiece in a sealed state.
[0020]
The differential pressure sensor 6 is connected between the branch passages 12a and 12b on the downstream side of the first on-off valves 4a and 4b via the introduction passages 15a and 15b.
[0021]
A volume changing means 20a is provided in the work side branch passage 12a on the downstream side of the first on-off valve 4a. The volume changing means 20a is connected to an auxiliary passage 21a having one end connected to the branch passage 12a, a normally open second on-off valve 22a provided in the middle of the auxiliary passage 21a, and the other end (downstream end). And a tank 23a having a predetermined volume. Similarly, the master side branch passage 12b on the downstream side of the first on-off valve 4b is provided with a volume changing means 20b including an auxiliary passage 21b, a second on-off valve 22b, and a tank 23b. The pair of tanks 23a and 23b have the same volume, for example, approximately the same as the master capsule 5b in which the master member M is accommodated.
[0022]
The volume of the work side closed system when the second on-off valve 22a is closed (before the volume changing operation) (that is, the volume of the branch passage 12a on the downstream side of the first on-off valve 4a and the volume of the work capsule 5a) And the volume of the auxiliary passage 21a on the upstream side of the second opening / closing valve 22a), and the volume of the master side closing system when the second opening / closing valve 22b is closed (the state before the volume changing operation) ( That is, the volume of the branch passage 12b on the downstream side of the first on-off valve 4b, the volume of the work capsule 5b, and the volume of the auxiliary passage 21b on the upstream side of the second on-off valve 22b) Equal to each other.
[0023]
Further, the volume of the work side closing system when the second opening / closing valve 22a is opened (the state after the volume changing operation) (that is, the volume of the work side closing system before the volume changing operation is downstream of the second opening / closing valve 22a). Volume of the auxiliary passage 21a on the side and the volume of the tank 23a), and the volume of the master side closing system in the state where the second on-off valve 22b is open (the state after the volume changing operation) (that is, the above volume changing operation) The volume obtained by adding the volume of the auxiliary passage 21b on the downstream side of the second opening / closing valve 22b and the volume of the tank 23b to the volume of the previous master side closing system is equal in design.
[0024]
Further, the air leak test apparatus includes a control unit 50 for controlling the various valves 3, 4a, 4b, 22a, 22b and the capsules 5a, 5b described above, and a display unit 60.
[0025]
Next, the operation (air leak test method) of the air leak test apparatus having the above configuration will be described. First, the measurement mode normally performed by the control unit 50 will be described. The work capsule 5a is closed in a state where the work W to be inspected is accommodated, and the master capsule 5b is closed in a state where the master member M which is a non-defective work is accommodated. After the first on-off valves 4a and 4b are open, the second on-off valves 22a and 22b are closed, and then the three-way valve 3 is turned on to supply the test pressure of the air pressure source 9 to the branch passages 12a and 12b. Thereafter, the first on-off valves 4a and 4b are closed and the detected differential pressure of the differential pressure sensor 6 is monitored for a predetermined time. If the detected differential pressure remains zero or does not change or is less than or equal to the minute leak determination value, it is determined that there is no minute leak. When the detected differential pressure exceeds the minute leak discrimination value, it is determined that there is a minute leak.
[0026]
Details of the minute leak determination in the present embodiment will be described. In the present embodiment, the detected differential pressure becomes a negative output when the pressure of the workpiece side closing system is lower than the pressure of the master side closing system, and becomes a positive output when it is high. When there is a minute leak in the workpiece W, the detected differential pressure is a negative output. The control unit 50 reverses the detected differential pressure, subtracts the minute leak determination value (having a positive polarity) from the inverted value, and if the subtracted value is positive, the controller 50 determines that there is a minute leak. In this case, it is determined that there is no minute leak.
The subtracted value is also displayed as a numerical value on the display unit 60, and the inspector can confirm the presence or absence of a minute leak with the polarity of the numerical value displayed on the display unit 60.
In the present embodiment, the above calculation is performed in order to facilitate the inspector's confirmation. However, the micro leak may be determined by simply comparing the detected differential pressure having the same polarity with the micro leak determination value.
[0027]
When it is determined that there is no minute leak, the control unit 50 opens the second on-off valves 22a and 22b. When the work-side second on-off valve 22a is opened, the work-side closing system pressure escapes to the tank 23a. That is, in the closed system on the workpiece side, only the volume ΔVw of the auxiliary passage 21a on the downstream side of the second on-off valve 22a and the tank 23a increases from the volume Vw in the state in which the second on-off valve 22a is closed. The pressure in the workpiece side closing system decreases from the pressure Pt to the pressure Pw. Similarly, when the master-side second on-off valve 22b is opened, the master-side closing system starts from the volume Vm in a state in which the second on-off valve 22b is closed to the auxiliary passage 21b on the downstream side of the second on-off valve 22b and the tank. The volume increases by the volume ΔVm of 23b, and accordingly, the pressure in the master side closed system also decreases from the pressure Pt to the pressure Pm.
[0028]
After changing the volumes of the work side closing system and the master side closing system by the same amount as described above, the detected differential pressure by the differential pressure sensor 6 is compared with the large leak discriminating value to determine whether there is a large leak. If there is a large leak in the workpiece W, the inside of the workpiece W is already at the test pressure before the volume change, so the inner volume of the workpiece side closed system substantially increases by the integral of the content of the workpiece W. The pressure drop after the change is small compared to the master side closed system. This differential pressure is detected by the differential pressure sensor 6. When the detected differential pressure is less than the large leak determination value, it is determined that there is no large leak, and when it exceeds the large leak determination value, it is determined that there is a large leak.
[0029]
Details of the large leak determination in the present embodiment will be described. When there is a large leak in the workpiece W, the detected differential pressure is a positive output in this embodiment. The control unit 50 subtracts the large leak determination value (having a positive polarity) from the detected differential pressure, and determines that there is a large leak when the subtraction value is positive, and there is no large leak when the value is negative. Judge. This subtracted value is also displayed on the display unit 60, and the inspector can easily confirm the presence or absence of a minute leak with the polarity of the numerical value displayed on the display unit 60.
[0030]
After finishing the leak determination, the control unit 50 opens the first on-off valves 4a and 4b and sets the three-way valve 3 to the atmospheric release position, so that all the air passages 10 on the downstream side of the three-way valve 3 are opened to the atmosphere. To.
When it is determined that there is no minute or large leak, the non-defective product is displayed by controlling the lamp of the display unit 60 and the like, and if there is a leak, the defective product is displayed.
[0031]
As described above, when the volumes of the work side closing system and the master side closing system are equal as designed and there is no large leakage in the work W, the differential pressure after the volume change should be zero. However, even if there is no major leak in the workpiece W, if the volumes before and after the volume change of the workpiece side closing system and the master side closing system are different from each other due to manufacturing errors, the detected differential pressure does not become zero. Therefore, in the present embodiment, this error is overcome by devising a method of setting the large leak discrimination value.
[0032]
Hereinafter, the mode for setting the large leak discrimination value implemented by the control unit 50 will be described in detail. This discriminant value setting mode is executed prior to the above-described measurement mode. First, a large number of good workpieces with no leakage and a number of defective workpieces with large leakages are prepared. Identification of non-defective and defective workpieces is performed in advance.
[0033]
The discrimination value setting mode is executed for each prepared work. More specifically, the control unit 50 closes the capsules 5a and 5b in a state where the workpiece W is accommodated in the workpiece capsule 5a and the master member M as a non-defective workpiece is accommodated in the master capsule 5b, and thereafter, the same as in the measurement mode. Then, the valves 3, 4a, 4b, 22a, 22b are operated. More specifically, the second on-off valves 22a and 22b are closed while the first on-off valves 4a and 4b are opened, and then the three-way valve 3 is turned on, whereby the test pressure of the air pressure source 9 is changed to the branch passage 12a, The capsules 5a and 5b are supplied via 12b. Next, by closing the first on-off valves 4a, 4b, the branch passages 12a, 12b and the capsules 5a, 5b on the downstream side of the first on-off valves 4a, 4b are closed. Next, the second on-off valves 22a and 22b are opened to change the volumes of the work side closing system and the master side closing system.
[0034]
After the volume change, the detected differential pressure of the differential pressure sensor 6 is read. After reading the detected differential pressure, the valves 4a, 4b, 22a and 22b are opened, the valve 3 is opened to the atmosphere, and the discriminant value setting mode for one time is finished.
[0035]
By repeating the discrimination value setting mode for a number of non-defective workpieces as the workpiece W accommodated in the workpiece capsule 5a, as shown in FIG. 2, the detected differential pressure (hereinafter referred to as first differential pressure data) Distribution). In addition, by repeatedly performing the discriminant value setting mode for a number of defective workpieces as the workpiece W, a distribution of detected differential pressure (hereinafter referred to as second differential pressure data) for the defective workpiece is also obtained.
[0036]
The control unit 50 calculates center values D1 and D2 (average values) of the distribution of the first and second differential pressure data. The difference A between the large leak determination value Dx and the first reference value D1 and the difference B between the large leak determination value Dx and the first reference value D2 become a specific ratio (A <B in this embodiment). As described above, the large leak discrimination value Dx is set and stored. Then, this large leak discrimination value Dx is used in the subsequent measurement modes.
[0037]
As described above, since the large leak discrimination value Dx is set between the detected differential pressure of the non-defective workpiece and the detected differential pressure of the defective workpiece, the large leak discrimination value Dx is detected at the time of the large leak inspection in the measurement mode. Similar to the differential pressure, it includes the differential pressure due to the error of the internal volume of the closed system on the work side and master side. By comparing this detected differential pressure with the large leak discrimination value Dx, The resulting differential pressure can be canceled out, and a decrease in the accuracy of the large leak determination due to this error can be avoided. In addition, the large leak discriminant value can be set in the discriminant value setting mode, so that it is possible to save the trouble of setting it independently for the workpiece.
[0038]
In this embodiment, since the large leak discrimination value Dx is calculated from the average value D1 of the detected differential pressures of a plurality of non-defective workpieces and the average value D2 of the detected differential pressures of a plurality of defective workpieces, The large leak determination value Dx can be set with high accuracy without being influenced by the error in the external volume. In addition, the non-defective workpiece that becomes the master member M is common in these multiple discriminant value setting modes, and is used as it is in the subsequent measurement mode. The large leak determination value Dx can be set with high accuracy, and the large leak determination can be performed with high accuracy.
[0039]
In the present embodiment, the difference A between the large leak determination value Dx and the first reference value D1 and the difference B between the large leak determination value Dx and the first reference value D2 are determined by a specific ratio (A in the present embodiment). Since the large leak determination value Dx is set so as to satisfy <B), the optimum large leak determination value Dx can be set according to the internal volume even if the type of workpiece to be inspected is changed.
[0040]
Returning to the measurement mode, a description will be added. As described above, in the measurement mode, if the value obtained by subtracting the detected differential pressure by the large leak discrimination value Dx (hereinafter referred to as the display differential pressure value) is positive, it is determined as a defective product. If it is negative, it is judged as a good product. That is, the apparent large leak discrimination value (display discrimination value) is set to zero. If the zero value is displayed as an apparent large leak determination value in this way, it is not necessary to change the apparent large leak determination value even if the type of workpiece changes.
As shown in FIG. 3, the difference between the average value of the display differential pressure value in the case of a non-defective product and the display discrimination value should be almost equal to the difference A in the discrimination value setting mode. Similarly, the difference between the average value of the display differential pressure value in the case of a defective product and the display discrimination value should be almost equal to the difference B in the discrimination value setting mode.
[0041]
In the above measurement mode, when the displayed differential pressure value is negative, it is determined to be a non-defective product, but when it is below the threshold “−Th”, it is determined that the master side closed system has failed. For example, when the master member is damaged and a large leak occurs, the displayed differential pressure value should appear in the vicinity of a value that is further lower than the threshold value “−Th” by B. The threshold “−Th” is set to twice the difference A, for example.
[0042]
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, components corresponding to those in the first embodiment are denoted by the same reference numerals in the drawing and description thereof is omitted. The control unit 50 and the display unit 60 are not shown. In the second embodiment, instead of the master capsule 5b in the first embodiment, a sealed container 30 is connected to the downstream end of the master side branch passage 12b, and the master side branch passage 12b is downstream of the first on-off valve 4b. Is blocked. The sealed container 30 has an internal volume that is substantially equal to a value obtained by subtracting the external volume of the work W from the internal volume of the work capsule 5a. As a result, the volume of the closed system on the master side is substantially equal to the volume of the closed system on the workpiece side. Here, “substantially equal” includes not only a case where they are equal in design, but also a case where there is a slight difference within an allowable range on the assumption that a plurality of types of workpieces having different external volumes are tested. Instead of the sealed container 30, the downstream end may be closed by extending the piping of the branch passage 12b.
[0043]
In the second embodiment, the measurement mode and the discriminant value setting mode executed by the control unit 50 are the same as those in the first embodiment, and a description thereof will be omitted.
[0044]
In the first and second embodiments, the discrimination value calculated in the discrimination value setting mode may be updated in the process of repeating the measurement mode. For example, the detected differential pressure (first differential pressure data) is stored every time it is determined as a non-defective product in the measurement mode, and the detected differential pressure (second Differential pressure data) and the first and second differential pressure data calculated in the discriminant value setting mode or the first and second differential pressure data updated in the previous measurement mode. In consideration of the above, these differential pressure data are updated, and the large leak determination value is updated based on these differential pressure data. In this case, the differential pressure data is calculated by moving average, load average, simple average, and the like. Thereby, it is possible to obtain a more accurate large leak discriminating value corresponding to a change with time of the apparatus and the environment.
[0045]
In the first and second embodiments, in the discriminant value setting mode, a non-defective product and a defective product are not recognized in advance, and the distribution of detected differential pressure is identified as a non-defective product distribution and a defective product distribution, and based on these distributions. In the same manner as in the above embodiment, the large leak determination value may be set. In this case, the discriminant value setting mode may be controlled similarly to the measurement mode. Alternatively, the measurement mode may be executed many times from the beginning, and the large leak determination value may be set based on the data. In this case, the initial measurement mode is the discriminant value setting mode.
[0046]
In the large leak discriminating value mode, the differential pressure data for the non-defective workpiece and the defective workpiece may not be so large as to form a distribution. For example, the discrimination value setting mode may be executed for several non-defective workpieces and defective products, and the first and second differential pressure data may be obtained from a simple average of the detected differential pressures. In a more extreme example, the first and second differential pressure data may be obtained by executing the discriminant value setting mode for one good product and one defective product. When the amount of data is small, the accuracy can be improved by updating the large leak discrimination value in the measurement mode as described above.
[0047]
The displayed differential pressure value may be positive for non-defective products and negative for defective products. In the discriminant value setting mode, the measurement order of non-defective workpieces and defective workpieces may be reversed. The volume changing means of the above embodiment may reduce the volume and increase the pressure in the branch passage. The test pressure may be a negative pressure.
[0048]
【The invention's effect】
As described above, according to the present invention, since the large leak discriminant value is obtained from the detected differential pressure in the non-defective workpiece and the defective workpiece, regardless of the volume error of the workpiece side closing system and the master side closing system, High-precision large leak determination can be performed.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an air leak test apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a data distribution of detected differential pressure when a discriminant value setting mode is executed.
FIG. 3 is a diagram showing a data distribution of detected differential pressure when a measurement mode is executed.
FIG. 4 is a circuit diagram of an air leak test apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
4a, 4b First open / close valve (open / close valve)
5a Work capsule
5b Master capsule
6 Differential pressure sensor
9 Air pressure source
11 Common passage
12a Work side branch passage
12b Master side branch passage
20a, 20b Volume changing means
50 Control unit
60 Display section
W Work
M Master member (non-defective work)

Claims

(A) a common passage connected to the air pressure source, a work side branch passage and a master side branch passage branched from the common passage,
(B) a pair of on-off valves respectively provided in the branch passage on the workpiece side and the master side;
(C) a work capsule connected to the downstream side of the on-off valve in the work side branch passage;
(D) a differential pressure sensor for detecting a differential pressure between the branch passage on the work side and the master side downstream of the on-off valve;
(E) a pair of volume changing means provided on the downstream side of the on-off valve in the work side and master side branch passages;
Execute measurement mode and discriminant value setting mode using an air leak test device equipped with
In the above measurement mode, with the work to be inspected for leakage contained in the work capsule, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, and this state By comparing the detected differential pressure of the differential pressure sensor with the micro leak discrimination value, the presence or absence of micro leak of the work is determined, and then the work side and master side closed systems are operated by operating a pair of volume changing means The presence or absence of a large leak in the workpiece is determined by comparing the detected differential pressure of the differential pressure sensor in this state with the large leak discrimination value.
In the discriminant value setting mode,
(I) In a state where a non-leakable work is contained in the work capsule and closed, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, By operating the pair of volume changing means, the volume of the closed system on the work side and the master side is changed by an equal amount, and the detected differential pressure of the differential pressure sensor in this state is obtained as the first differential pressure data,
(Ii) Supplying the test pressure of the air pressure source to the branch passage on the work side and the master side in a state where the defective work piece causing the large leak in the work capsule is accommodated and closed, and then closing the pair of on-off valves, Next, the volume of the closed system on the workpiece side and the master side is changed by an equal amount by operating a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as second differential pressure data,
(Iii) An air leak test method characterized in that a value between the first differential pressure data and the second differential pressure data is set as the large leak determination value.

In the master side branch passage, a master capsule is connected to the downstream side of the on-off valve, and in the measurement mode and the discriminant value setting mode, a non-defective workpiece with no common leakage is accommodated as a master member in the master capsule. The air leak test method according to claim 1.

In the discriminant value setting mode, the average value of the first differential pressure data is obtained for a plurality of non-defective workpieces, the average value of the second differential pressure data is obtained for a plurality of defective workpieces, and the large value is calculated based on these average values. The air leak test method according to claim 1, wherein a leak discrimination value is set.

The large leak determination value is set so that the difference between the large leak determination value and the average value of the first differential pressure data and the difference between the large leak determination value and the average value of the second differential pressure data become a predetermined ratio. The air leak test method according to claim 3.

In the above measurement mode, the detected differential pressure when it is determined that there is no major leakage of the workpiece is used as the first differential pressure data, and the detected differential pressure when it is determined that there is a large workpiece leak is used as the second differential pressure data. 5. The air leak test method according to claim 1, wherein the large leak determination value is updated based on the first differential pressure data and the second differential pressure data.

(A) a common passage connected to the air pressure source, a work side branch passage and a master side branch passage branched from the common passage,
(B) a pair of on-off valves provided in the branch passage on the workpiece side and the master side, and (c) a work capsule connected to the downstream side of the on-off valve in the branch passage on the workpiece side,
(D) a differential pressure sensor for detecting a differential pressure between the branch passage on the work side and the master side downstream of the on-off valve;
(E) a pair of volume changing means provided on the downstream side of the on-off valve in the work side and master side branch passages;
(F) In the measurement mode, with the work to be inspected for leakage contained in the work capsule, supply the test pressure of the air pressure source to the branch passage on the work side and the master side, and then close the pair of on-off valves, In this state, the presence or absence of minute leakage of the workpiece is determined by comparing the detected differential pressure of the differential pressure sensor and the minute leakage determination value, and then the workpiece side and master side are operated by operating a pair of volume changing means. A control unit that determines the presence or absence of a large leak of the workpiece by changing the volume of the closed system in an equal amount, and comparing the detected differential pressure of the differential pressure sensor in this state with a large leak discrimination value
In an air leak test apparatus equipped with
The control unit further executes a discriminant value setting mode, and in this discriminant value setting mode,
(I) In a state where a non-leaked work piece is contained in the work capsule and closed, the test pressure of the air pressure source is supplied to the branch passage on the work side and the master side, and then the pair of on-off valves are closed, The volume of the closed system on the workpiece side and the master side is changed by an equal amount by driving a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as first differential pressure data,
(Ii) Supplying the test pressure of the air pressure source to the branch path on the work side and master side with the closed work piece containing a defective work that causes a large leak in the work capsule, and then closing the pair of on-off valves Then, the volume of the closed system on the work side and the master side is changed by an equal amount by driving a pair of volume changing means, and the detected differential pressure of the differential pressure sensor in this state is obtained as second differential pressure data,
(Iii) An air leak test apparatus characterized in that a value between the first differential pressure data and the second differential pressure data is set and stored as the large leak determination value.

7. The apparatus according to claim 6, further comprising a display unit, wherein the control unit subtracts the large leak determination value from the detected differential pressure when the large leak is detected in the measurement mode, and displays the value on the display unit. The air leak test device described in 1.