JP4154077B2

JP4154077B2 - Air leak detection method for sealed containers

Info

Publication number: JP4154077B2
Application number: JP16340899A
Authority: JP
Inventors: 彰福島
Original assignee: 株式会社ヒット開発研究所
Priority date: 1999-06-10
Filing date: 1999-06-10
Publication date: 2008-09-24
Anticipated expiration: 2019-06-10
Also published as: JP2000352543A

Description

【０００１】
【発明の属する技術分野】
本発明は、密閉容器のエアリーク検出方法、特に容易な構造で密閉容器のエアリークの有無を検出することのできる密閉容器のエアリーク検出方法に関する。
【０００２】
【従来の技術】
従来から内部に空室を残して密閉される容器が各種の産業分野において用いられている。例えばマイクロ電子部品であるシールリレーは、プラスチック容器内に可動接点と励磁コイルとが収納され、この容器をシールすることによって密封された小型小電力リレー素子を得ることができる。この様なシールリレーは、容器内で密閉された空気あるいは不活性ガスがリレーの可動部やその他の内部部品を安定した状態に保つと共に、当該内部部品が塵埃等の影響を受けないことから長期間に渡ってマイクロ電子部品の安定した作動特性を保つことが可能になる。もちろん、密封容器は前述したようなマイクロ電子部品ばかりでなく、医療用、食品用、その他広範囲の分野に適用可能であり、同様に密閉容器内の物体の安定化や保護を行うことができる。
【０００３】
この様な密封容器は、製造時におけるシール不良、容器自体の破損や通孔その他の存在によって完全な密封状態を保つことができない場合がある。この様な密閉状態が害された密閉容器は、エアリークを起こしているものとして不良品として確実に除去されなければならない。この判別を行うためにエアリーク検出方法が幾つか提案されている。
【０００４】
以前は、密封容器をフロン液等に浸漬した状態で加温あるいは減圧をおこない、この時にフロン液内に生じる気泡を検出してリークの有無が判定されていたが、環境保護の観点からフロン液の使用が禁止された今日では、他の方法によるエアリーク検出が要望されている。例えば、差圧式と称される検出方法では、圧力バランス検出器を挟んで接続された二つの密閉槽を準備し、一方の密閉槽に被測定密閉容器を収納し、他方の密閉槽にエアリークの無い基準密閉容器を収納する。この状態で、各密閉槽を減圧または加圧して同一の一定圧空間を形成する。もし、被測定密閉容器にリークが存在すれば、被測定密閉容器の内部空間が密閉槽の内部空間と同化することになり二つの密閉槽の圧力バランスが崩れる。この崩れを検出することによりリークの有無判定を行うことができる。
【０００５】
【発明が解決しようとする課題】
しかし、この様な従来の差圧方式の装置においては、密閉槽内の圧力を安定化させるために充分な平衡時間を必要とし、検査時間の短縮が計れないという問題があった。また、前記密閉槽の内圧を安定化させるためには、充分に大きな加圧源或いは減圧源が必要となり、装置が大型化し、またリーク検査のためのみに大きなエネルギーを必要とするという欠点があった。また、密閉槽内の圧力が安定した後、徐々にエアリークする非完全リーク、いわゆる小リーク、中リークに関しては、圧力バランスの崩れを検出できるが、完全リーク（大きな穴等により激しいリークを起こす大リーク）が存在する場合、加圧または減圧の開始時には既に被測定密閉容器の内部空間が密閉槽の内部空間と同化しているため、完全リークが正確に検出できない虞がある。
【０００６】
本発明は上記従来の課題に鑑みなされたものであり、その目的は、容易な構成で迅速かつ正確な完全リーク及び非完全リークの有無判定を行うことのできるエアリーク検出装置を提供することである。
【０００７】
【課題を解決するための手段】
上記のような目的を達成するために、本発明は、被測定密閉容器（１２）を収納可能な所定容積の密閉空間を形成可能な測定槽（１４）と、基準容積（Ｖ１）を有する基準圧力室（２８）と、減圧装置（１６）と、測定槽（１４）と基準圧力室（２８）の選択的な連通を許容する切換バルブ（Ｖａ）と、基準圧力室（２８）と減圧装置（１６）の選択的な連通を許容する切換バルブ（Ｖｂ）と、測定槽（１４）内の圧力を測定する圧力センサ（１８）と、被測定密閉容器（１２）のエアリークの有無を判定する判定部と、を含むエアリーク検出装置を用いた密閉容器のエアリーク検出方法において、測定槽（１４）と基準圧力室（２８）とを大気圧にするステップと、切換バルブ（Ｖａ）を閉じて測定槽（１４）と基準圧力室（２８）との連通を遮断し、切換バルブ（Ｖｂ）を開放して基準圧力室（２８）と減圧装置（１６）とを連通させて、減圧装置（１６）により基準圧力室（２８）を基準圧力状態まで減圧するステップと、切換バルブ（Ｖｂ）を閉じて基準圧力室（２８）と減圧装置（１６）との連通を遮断した後に、切換バルブ（Ｖａ）を開放して測定槽（１４）と基準圧力室（２８）とを連通させて、測定槽（１４）の気体と基準圧力室（２８）の気体とを混合させるステップと、混合した気体の槽内圧力値（Ｐｘ）を圧力センサ（１８）により測定するステップと、切換バルブ（Ｖａ）と切換バルブ（Ｖｂ）とを開放にして測定槽（１４）と基準圧力室（２８）と減圧装置（１６）とを連通させて、減圧装置（１６）により測定槽（１４）を基準圧力状態まで減圧した後に切換バルブ（Ｖａ）を閉じるステップと、測定槽（１４）内の基準圧力状態値（Ｐｖ）を圧力センサ（１８）により測定するステップと、槽内圧力値（Ｐｘ）と基準圧力状態値（Ｐｖ）とで規定される変動比を左辺とし、基準圧力室（２８）の基準容積（Ｖ１）と、エアリークのない基準密閉容器を収納した場合の測定槽（１４）の残余容積（Ｖ２）に基準容積（Ｖ１）を加えた総合容積とで規定される固定比を右辺とする式Ｐｘ／Ｐｖ＝Ｖ１／（Ｖ１＋Ｖ２）に基づいて判定部が被測定密閉容器（１２）の完全エアリークを判定するステップと、を有することを特徴とする。
【０００８】
ここで、前記測定槽と基準圧力室は、変形による容積変化を起こさない空間を有し、連通切換機構（例えば、切換バルブ）を介した測定槽と基準圧力室との連通は、極力短い経路により行われることが好ましい。なお、連通経路の容積は、測定槽または基準圧力室のいずれか一方に含まれるものとし、基準圧力室の圧力状態は測定槽の初期槽内圧力に対して減圧または加圧した状態とする。
【０００９】
この構成によれば、被測定密閉容器にエアリークが存在する場合、当該被測定密閉容器の内部空間が測定槽の内部空間と同化し、実質的な内部容積が増加するため、測定槽と基準圧力室とが連通した後に測定槽の到達する圧力がエアリークが存在しない場合に対して上昇（基準圧力室を測定槽に対して減圧した場合）または下降（基準圧力室を測定槽に対して加圧した場合）する。この圧力変化に基づいてエアリークの有無を判定する。この時、測定準備のための測定槽内の圧力安定化を行う必要が無いので、測定槽と基準圧力室とを連通させる容易な構成で迅速な判定を行うことが可能になる。
【００１１】
この構成によれば、エアリークが存在した場合、測定槽の残余容積が増加することになり、容積によって規定されるエアリークが存在しない場合の固定比に対して圧力で規定される変動比が変化する。従って、エアリークの有無を確実に検出することができる。この時、被測定密閉容器に完全エアリーク、いわゆる大リークがある場合でも、測定槽と基準圧力室との連通後の圧力変化に基づいて判定を行っているため完全エアリークを正確に検出することができる。
【００１２】
上記のような目的を達成するために、本発明は、前記構成において、前記判定部は、前記測定槽と基準圧力室との連通から所定時間測定槽内圧力を測定し、その時の圧力変化量に基づいて被測定密閉容器の非完全エアリークを検出することを特徴とする。
【００１３】
ここで、連通から所定時間とは、例えば、測定槽と基準圧力室との連通後、５〜６秒程度である。
【００１４】
この構成によれば、徐々に被測定密閉容器内のエアがリークする非完全エアリークの場合でもそのリークによる圧力変化量を検出することが可能になり、非完全エアリーク、特に小リークを確実かつ容易に検出することができる。
【００１５】
上記のような目的を達成するために、本発明は、前記構成において、前記判定部は、前記測定槽と基準圧力室との連通後、所定時間経過後の短時間に変化する測定槽内圧力の圧力変化量に基づいて被測定密閉容器の非完全エアリークを検出することを特徴とする。
【００１６】
ここで、連通後所定時間経過後の短時間とは、例えば、測定槽と基準圧力室との連通後、０．３秒程度経過後の０．１秒間程度である。
【００１７】
この構成によれば、非完全リークの中でも大リークと小リークの中間程度の中リークが発生する場合でも初期段階の圧力変化に基づく判断を行うのでエアリークの程度を含めて迅速に判定することが可能になる。
【００１８】
【発明の実施の形態】
以下、本発明の好適な実施の形態（以下、実施形態という）を図面に基づき説明する。
【００１９】
図１は本実施形態のエアリーク検出装置１０の基本構成概念を説明する概略説明図である。エアリーク検出装置１０は、被測定密閉容器、例えばマイクロ電子部品であるシールリレー（以下、ワークという）１２を収納し検査を行う測定槽１４と、当該測定槽１４に連通切換機構として複数の切換バルブ（本実施形態では４個の切換バルブＶa，Ｖb，Ｖc，Ｖd）を介して接続された減圧装置１６と、前記測定槽１４の近傍に配置され測定槽１４内の槽内圧力を検出可能な圧力センサ１８と、減圧装置１６、圧力センサ１８、各切換バルブＶa，Ｖb，Ｖc，Ｖd等の制御及び検出値等に関する演算を行い所定の判定出力を行う判定部を含む制御部２０等で構成されている。
【００２０】
前記測定槽１４は、例えば、ヒンジ等で接続された上部筐体１４ａと下部筐体１４ｂで構成された開閉自在なケースで、上部筐体１４ａと下部筐体１４ｂを接合した状態（閉状態）でほぼ中央部にワーク１２を収納する測定室２２を形成する。この測定室２２の周囲には、閉状態における当該測定室２２の気密を確保するために、気密シール部材として例えばＯリング２４が配置される。従って、上部筐体１４ａと下部筐体１４ｂとにより、所定容積の実質的密閉空間を有する測定室２２を形成することが可能になる。なお、測定室２２は圧力変化等によって、内壁面が変形したりしないように、上部筐体１４ａと下部筐体１４ｂ全体または内壁面が金属や硬質樹脂等で形成されている。
【００２１】
一方、前記減圧装置１６は、真空ポンプ１６ａとレギュレータ１６ｂを有する減圧タンク１６ｃで構成され、減圧タンク１６ｃ内を常に所定の圧力に維持できるように成っている。また、切換バルブＶa，Ｖb，Ｖdは、測定槽１４と減圧装置１６とを連通接続する流路２６を選択的に開閉を行っている。特に、切換バルブＶaと切換バルブＶbとの間に形成される空間は、前記測定槽１４に対して、異なる圧力状態を形成可能な基準圧力室２８を規定している。また、切換バルブＶcは、大気開放用の弁であり、流路２６及び測定槽１４の測定室２２の圧力を大気開放する場合に開かれる。
【００２２】
本実施形態の特徴的事項は、測定槽１４と当該測定槽１４と内部圧力の異なる基準圧力室２８とを選択的に連通させることにより、測定槽１４内部の圧力を変化させて、その時の圧力変化状態に応じて、測定槽１４に収納したワーク１２のエアリークの有無を判定するところである。すなわち、ワーク１２の密閉の完全または非完全によって、ワーク１２の内部空間１２ａが測定槽１４の残余空間２２ａ（ワーク１２の体積を除いた測定槽１４の内部空間）と独立または同化する。その結果、測定槽１４の実質的残余空間（残余容積）が変動し、測定槽１４と基準圧力室２８との連通時の到達圧力が変動する。この変動に基づいてエアリークの有無判定を行う。なお、図１において、測定室２２にワーク１２を配置した場合に、測定室２２の残余空間２２ａが比較的大きく描かれているが、実際は、測定室２２の容積はワーク１２の体積より僅かに大きいだけで、ワーク１２の内部空間１２ａの同化による測定槽１４内の空間の変動量が顕著に現れるようになっている。例えば、ワーク１２の内部空間１２ａが０．１ｃｃの場合、測定室２２の残余空間２２ａを１．５ｃｃに設定し、この時の基準圧力室２８の容量を、例えば、０．８ｃｃに設定する。
【００２３】
図２に示す切換バルブＶa，Ｖb，Ｖc，Ｖdの動作テーブル表及び、図３に示す測定槽１４の測定室２２の圧力変化図を用い、図１のエアリーク検出装置１０の動作を説明する。なお、本実施形態では大気圧は一定であるとする。
【００２４】
まず、判定準備として、測定槽１４の測定室２２に判定対象のワーク１２を投入する。この時、制御部２０は、切換バルブＶa，Ｖbのみ開く（タイミングＴ１）。従って、測定槽１４と切換バルブＶa，Ｖbで規定される基準圧力室２８は連通する。続いて、測定槽１４の上部筐体１４ａと下部筐体１４ｂを密着させ（蓋閉め動作）、測定槽１４を実質的密閉状態にする。この蓋閉め動作により測定室２２を含む空間の内部圧力は上昇してしまうので、制御部２０は、切換バルブＶa，Ｖbに続いて、切換バルブＶcを開放し、測定室２２及び基準圧力室２８の圧力を大気圧（Ｐ0＝１０１３×１０²Ｐａ）にする（タイミングＴ２）。次に、切換バルブＶa，Ｖcを閉じ、切換バルブＶdを開放する（タイミングＴ３）。この操作により、基準圧力室２８を含む空間が減圧装置１６に接続され、減圧装置１６で制御される。この時、減圧装置１６では、例えば、ＰV＝０．４ｋｇｆ／ｃｍ²（３９２×１０²Ｐａ）に減圧する。この状態で、切換バルブＶb，Ｖdを閉じる。すなわち、全ての切換バルブを閉じて、基準圧力状態値Ｐ1（大気圧から３９２×１０²Ｐａ減圧した負圧状態）の所定容積（０．８ｃｃ）を有する基準圧力室２８を形成し、制御部２０は測定準備を完了する（タイミングＴ４）。
【００２５】
制御部２０に測定開始信号が与えられると、制御部２０は切換バルブＶaのみを開放し（タイミングＴ５）、測定槽１４（測定室２２）と基準圧力室２８とを連通させ、測定槽１４（測定室２２）の内部圧力を変化（減圧）させる。
【００２６】
制御部２０は、切換バルブＶaのみを開放した状態で圧力センサ１８を制御して、経過時間Ｂ（切換バルブＶaの開放後０．３秒経過）と経過時間Ｃ（切換バルブＶaの開放後０．４秒経過）時点の測定室２２の圧力（例えばＰXa，ＰXb）を測定する（図３参照）。続いて、制御部２０は、切換バルブＶa，Ｖb，Ｖdを所定時間（例えば、経過時間Ｃ−Ｄ間；０．４秒）開放し、測定室２２を基準圧力室２８の当初の基準圧力状態値Ｐ1まで減圧し（タイミングＴ６）、切換バルブＶaを閉じて（タイミングＴ７）、所定時間（例えば、３秒）経過後、測定室２２の圧力（例えばＰXd）を測定する。この時、ワーク１２にエアリークが存在しない場合、測定室２２の圧力センサ１８の測定値はＰXd＝ＰVとなる。さらに、制御部２０は、ＰXd測定後、所定時間（例えば、２秒）の測定室２２の圧力（例えば、ＰXc）を測定し、エアリーク判定のための圧力測定を終了する。
【００２７】
続いて、制御部２０は、エアリーク判定処理を開始する。ところで、測定槽１４の測定室２２と基準圧力室２８との間にはボイルシャルルの法則により以下のような関係が成り立つ。
【００２８】
【数１】

この時、Ｐ1＝Ｐ0−ＰV，Ｐ2＝Ｐ0−ＰXであるから、式１を整理すると、
【数２】

となる。なお、測定室２２と基準圧力室２８の接続時に気体温度が変化するが、所定時間後には安定し変化しないものとする。
【００２９】
従って、経過時間Ｃで測定された測定室２２の圧力ＰX（ＰXa）と基準圧力室２８の基準圧力状態値ＰV（ＰXd）とは、基準圧力室の基準容積Ｖ1と、当該基準容積Ｖ1にワーク１２を収納した場合の測定槽１４の残余容積Ｖ2を加えた総合容積で規定される固定値と関連付けることができる。ワーク１２にエアリークが存在しない場合、すなわちワーク１２が完全に密閉された『良品』である場合、基準圧力室の基準圧力状態値ＰVと、基準圧力室２８と測定槽１４を連通させた後に測定される測定槽１４の槽内圧力値ＰX（ＰXa）で規定される値は、エアリークが存在しない場合の測定槽１４の容積Ｖ1と基準圧力室２８の容積Ｖ2とで規定される値と一致することになる。例えば、Ｖ1＝０．８ｃｃ、Ｖ2＝１．５ｃｃの場合、ＰX／ＰVの値がＶ1／（Ｖ1＋Ｖ2）＝０．８／２．３＝０．３４７８になる。一方、ワーク１２が完全にリークした『完全リーク品（大リーク）』である場合、Ｖ1／（Ｖ1＋Ｖ2）＝０．８／２．４＝０．３３３３になる。従って、エアリークのない良品を収納した場合の、測定槽１４と基準圧力室２８の容積で規定される固定比Ｖ1／（Ｖ1＋Ｖ2）を判定基準として、それに対応する基準圧力室の基準圧力状態値ＰV（ＰXd）と測定槽１４と連通させた後に測定される測定槽１４の槽内圧力値ＰX（ＰXa）とによる変動比を算出することにより『良品』か『完全リーク品』かを判定することができる。なお、厳密な判定を行うためには、判定値として、Ｖ1／（Ｖ1＋Ｖ2）＝０．３４７８の値を用いることが好ましいが、測定誤差を考慮して、良品と判定する判定値を例えば、０．３４００に取っておけば、実用的な大リークの判定を良好に行うことができる。なお、ＰV，ＰXはほぼ同時期に測定するので、測定時の大気圧は、ほぼ一定であると見なすことができるので、判定は良好に行うことができる。
【００３０】
図３には、測定槽１４に良品のワーク１２を収納して測定した場合の圧力変化（図中実線Ａ）と完全にエアリーク（大リーク）を起こしているワーク１２を測定槽１４に収納して測定を行った場合の圧力変化（図中破線Ｂ）を示している。図から、大リークを起こしている場合には、測定槽１４内の実質的な容積が増加するため減圧率が低下していることがわかる。なお、図３において、経過時間Ａ−Ｃ間で一時的に圧力が低下した後再び上昇しているのは、空気を急激に減圧すると空気が急冷され（断熱膨張）、この時、急冷された空気は回りの熱を奪って常温に戻る。この温度変化が圧力変化を引き起こす。その結果上述のような一時的な圧力低下が発生する。なお、本実施形態においては、大リークを起こしている場合、経過時間Ｃ後に測定槽１４内が基準圧力室２８の初期圧力に減圧されるので、圧力変化は、良品と同じになっている。
【００３１】
このように、測定槽１４と基準圧力室２８の容積で規定される固定比と測定槽１４と基準圧力室２８とを連通させた後に測定される測定槽１４内圧力と被測定密閉容器を収納した測定槽を基準圧力室の基準圧力状態値にした後所定時間経過後の測定槽内圧力とで規定される変動比とを比較することにより、迅速かつ正確に大リークの有無判定を行うことができる。
【００３２】
続いて、制御部２０は、極僅かずつワーク１２内のエアが漏れる非完全リークすなわち小リークの有無を検出する。小リークの場合、リーク量が極僅かであるため、測定槽１４と基準圧力室２８を連通させて、測定室２２の圧力を変化させても、連通直後の圧力変化は、良品と同じ変化を示す。そのため、制御部２０は、タイミングＴ７で切換バルブＶaを閉じて、所定時間（例えば、３秒；経過時間Ｅ）経過後に測定した測定室２２の圧力（ＰXd）と、ＰXd測定後、所定時間（例えば、２秒；経過時間Ｆ）の測定室２２の圧力（ＰXc）を用いて、密閉された測定槽１４内部の所定時間後の圧力変化量を測定する。小リークが発生している場合、測定槽１４の内部圧力は、エアリークによって徐々に増加していくので、良品の場合と、その変化率は異なる（小リーク時の圧力変化を図３中三点鎖線Ｃで示す）。測定槽１４の内部圧力を減圧してから所定時間後の圧力変化（開花時間Ｅ−Ｆ）を測定し良品の場合の圧力変化と比較することにより、小リークが発生している場合でも適切なリーク判定を行うことができる。なお、図３中の経過時間Ｃ−Ｆで測定槽１４内の圧力が一度急激に低下した後徐々に上昇している。これも前述した断熱膨張によるもので、良品のワーク１２の場合も僅かな圧力変化を起こしている。小リークが存在する場合には、その変化率がエアリーク分大きくなる。
【００３３】
さらに、ワーク１２のエアリークの中には、前述した大リークと小リークの中間程度のエアリーク、いわゆる中リークが発生する場合がある。この場合、図３中に一点鎖線Ｄで示すように、中リークは、例えば図３中の経過時間Ｄ−Ｅまでに完了してしまうものである。その結果、小リークを判定する経過時間Ｅ−Ｆ間では、断熱膨張による圧力変化のみ、すなわち良品（図３中実線Ａ）と同じ圧力変化を示してしまい、適切なリーク判定を行うことができなくなる。一方、図３に示すように、大リークを判定する経過時間Ｃ，ＥにおけるＰX／ＰVの値は、共に増加してしまうので、Ｖ1／（Ｖ1＋Ｖ2）で規定する固定比（容積比）に対する変動比（圧力比）による判定は行うことができない（良品と判断する可能性がある）。そこで、中リークを判定するためには、測定槽１４と基準圧力室２８とを連通させた直後（経過時間Ｂ−Ｃ；例えば、０．１ｓ）の圧力変化に注目する。図３に示すように、中リークを起こしている場合、経過時間Ｂ−Ｃ間でもエアリークにより測定槽１４の内部圧力が良品の場合より上昇する。この短時間における圧力変化率を良品の場合の圧力変化率と比較することにより中リークの存在判定を行う。
【００３４】
以上説明したように、測定槽１４に対して、所定の基準容積と基準圧力状態値とを有する基準測定室２８を選択的に接続して測定槽１４の圧力変化を観察することにより、制御部２０は大リーク、中リーク、小リークといった全てのエアリークを識別自在に確実に判定することが可能であり、その結果を例えば、『良品』、『大リーク』、『中リーク』、『小リーク』のように出力する。この時、測定槽１４と基準圧力室２８との接続を行い圧力変化を測定するのみなので、容易な構成で迅速かつ正確な完全リーク及び非完全リークの有無判定を行うことができる。
【００３５】
なお、本実施形態では、基準圧力室２８を減圧する例を説明したが、基準圧力室２８を加圧状態にして測定槽１４の槽内圧力を変化させても同様な判定を行うことができる。また、本実施形態では測定槽１４を大気圧としたが、基準圧力室２８と異なる圧力状態であれば、減圧状態でも加圧状態でも本実施形態と同様の効果を得ることができる。
【００３６】
【発明の効果】
本発明によれば、被測定密閉容器にエアリークが存在する場合、当該被測定密閉容器の内部空間が測定槽の内部空間と同化し、実質的な内部容積が増加するため、測定槽と基準圧力室とが連通した後に測定槽の到達する圧力がエアリークが存在しない場合に対して上昇（基準圧力室を測定槽に対して減圧した場合）または下降（基準圧力室を測定槽に対して加圧した場合）する。この圧力変化に基づいてエアリークの有無を正確に判定する事が可能になる。この時、測定準備のための測定槽内の圧力安定化を行う必要が無いので、測定槽と基準圧力室とを連通させる容易な構成で迅速な判定を行うことが可能になる。
【図面の簡単な説明】
【図１】本発明の実施形態に係るエアリーク検出装置の構成概念を説明する説明図である。
【図２】本発明の実施形態に係るエアリーク検出装置の切換バルブの動作タイミングを示すタイミング説明図である。
【図３】本発明の実施形態に係るエアリーク検出装置を使用したときの各エアリークの発生時の圧力変化を説明する説明図である。
【符号の説明】
１０エアリーク検出装置、１２ワーク、１２ａ内部空間、１４測定槽、１４ａ上部筐体、１４ｂ下部筐体、１６減圧装置、１８圧力センサ、２０制御部、２２測定室、２２ａ残余空間、２４Ｏリング、２６流路、２８基準圧力室、Ｖa，Ｖb，Ｖc，Ｖd 切換バルブ。[0001]
BACKGROUND OF THE INVENTION
The present invention, air leak detection method of the sealed vessel, to air leak detection method of the sealed container capable of detecting the presence or absence of air leak in the closed container in a particularly simple structure.
[0002]
[Prior art]
Conventionally, containers that are sealed with an empty space inside are used in various industrial fields. For example, a seal relay, which is a microelectronic component, has a movable contact and an exciting coil housed in a plastic container, and a sealed small power relay element can be obtained by sealing the container. Such a seal relay is long because the air or inert gas sealed in the container keeps the movable part of the relay and other internal parts in a stable state, and the internal parts are not affected by dust or the like. It becomes possible to maintain stable operating characteristics of the microelectronic component over a period of time. Of course, the sealed container can be applied not only to the microelectronic parts as described above but also to a wide range of fields such as medical use, food use, and the like. Similarly, the object in the sealed container can be stabilized and protected.
[0003]
Such a sealed container may not be able to maintain a complete sealed state due to poor sealing at the time of manufacture, breakage of the container itself, through holes, or the like. The sealed container in which such a sealed state is damaged must be surely removed as a defective product as an air leak has occurred. Several air leak detection methods have been proposed to make this determination.
[0004]
In the past, heating or decompression was performed with the sealed container immersed in chlorofluorocarbon, etc., and at this time, air bubbles generated in the chlorofluorocarbon were detected to determine the presence or absence of leaks. Today, the use of is prohibited, and there is a demand for air leak detection by other methods. For example, in a detection method called a differential pressure type, two sealed tanks connected with a pressure balance detector are prepared, a measured sealed container is stored in one sealed tank, and air leaks are stored in the other sealed tank. Contains no standard airtight container. In this state, each sealed tank is depressurized or pressurized to form the same constant pressure space. If there is a leak in the sealed container to be measured, the internal space of the sealed container to be measured is assimilated with the internal space of the sealed tank, and the pressure balance between the two sealed tanks is lost. By detecting this collapse, it is possible to determine whether or not there is a leak.
[0005]
[Problems to be solved by the invention]
However, in such a conventional differential pressure type apparatus, there is a problem that a sufficient equilibration time is required to stabilize the pressure in the sealed tank, and the inspection time cannot be shortened. In addition, in order to stabilize the internal pressure of the closed tank, a sufficiently large pressure source or a reduced pressure source is required, the apparatus is enlarged, and a large amount of energy is required only for leak inspection. It was. In addition, the non-complete leak that gradually leaks air after the pressure in the sealed tank is stabilized, so-called small leak and medium leak, can detect the pressure balance collapse, but complete leak (large leaks caused by large holes etc. If there is a leak), the internal space of the sealed container to be measured has already been assimilated with the internal space of the sealed tank at the start of pressurization or decompression, and thus there is a possibility that the complete leak cannot be detected accurately.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an air leak detection apparatus capable of quickly and accurately determining the presence or absence of complete leak and incomplete leak with an easy configuration. .
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention is perforated with formable measuring tank a closed space of predetermined volume capable of accommodating the object to be measured sealed container (12) (14), the reference volume of (V1) the reference pressure chamber (28), decompressor (16), a switching valve for permitting selective communication measuring Joso (14) and the reference pressure chamber (28) (Va), the reference pressure chamber (28) a switching valve for permitting selective communication of the pressure reducing device (16) (Vb), and a pressure sensor (18) for measuring the pressure in the measuring Joso (14), whether the air leak of the measured closed container (12) In the air leak detection method for an airtight container using an air leak detection device including the determination unit, the step of bringing the measurement tank (14) and the reference pressure chamber (28) to atmospheric pressure, and the switching valve (Va) Close and connect the measurement tank (14) and the reference pressure chamber (28). Is cut off, the switching valve (Vb) is opened to connect the reference pressure chamber (28) and the pressure reducing device (16), and the pressure reducing device (16) reduces the reference pressure chamber (28) to the reference pressure state. After the step and the switching valve (Vb) are closed and the communication between the reference pressure chamber (28) and the pressure reducing device (16) is shut off, the switching valve (Va) is opened and the measuring tank (14) and the reference pressure chamber ( 28), the step of mixing the gas in the measurement tank (14) and the gas in the reference pressure chamber (28), and the pressure value (Px) in the tank of the mixed gas is measured by the pressure sensor (18). The measuring valve (14), the reference pressure chamber (28), and the decompression device (16) are opened by opening the switching valve (Va) and the switching valve (Vb), and the decompression device (16). The measuring tank (14) was depressurized to the reference pressure state. The step of closing the switching valve (Va), the step of measuring the reference pressure state value (Pv) in the measurement tank (14) by the pressure sensor (18), the tank pressure value (Px) and the reference pressure state value ( Pv) is defined as the left side, the reference volume (V1) of the reference pressure chamber (28), and the remaining volume (V2) of the measurement tank (14) when the reference sealed container without air leak is stored. Based on the expression Px / Pv = V1 / (V1 + V2) having a fixed ratio defined by the total volume plus the reference volume (V1) as the right side, the determination unit determines complete air leak of the sealed container (12) to be measured. And a step .
[0008]
Here, the measurement tank and the reference pressure chamber have a space that does not cause a volume change due to deformation, and the communication between the measurement tank and the reference pressure chamber via a communication switching mechanism (for example, a switching valve) is as short as possible. Is preferably carried out by Note that the volume of the communication path is included in either the measurement tank or the reference pressure chamber, and the pressure state of the reference pressure chamber is reduced or increased with respect to the initial internal pressure of the measurement tank.
[0009]
According to this configuration, when there is an air leak in the measured sealed container, the internal space of the measured sealed container is assimilated with the internal space of the measurement tank, and the substantial internal volume increases. After reaching the chamber, the pressure reached by the measuring tank rises (when the reference pressure chamber is depressurized with respect to the measuring tank) or descends when the air leak does not exist (pressurizes the reference pressure chamber against the measuring tank) If you do). The presence or absence of air leak is determined based on this pressure change. At this time, since it is not necessary to stabilize the pressure in the measurement tank for measurement preparation, it is possible to make a quick determination with an easy configuration in which the measurement tank and the reference pressure chamber communicate with each other.
[0011]
According to this configuration, when there is an air leak, the remaining volume of the measurement tank increases, and the fluctuation ratio defined by the pressure changes with respect to the fixed ratio when there is no air leak defined by the volume. . Therefore, the presence or absence of air leak can be reliably detected. At this time, even if there is a complete air leak in the sealed container to be measured, so-called large leak, the determination is based on the pressure change after communication between the measurement tank and the reference pressure chamber, so that the complete air leak can be detected accurately. it can.
[0012]
In order to achieve the above object, according to the present invention, in the above configuration, the determination unit measures a pressure in the measurement tank for a predetermined time from communication between the measurement tank and a reference pressure chamber, and a pressure change amount at that time And detecting a non-complete air leak in the sealed container to be measured.
[0013]
Here, the predetermined time from the communication is, for example, about 5 to 6 seconds after the communication between the measurement tank and the reference pressure chamber.
[0014]
According to this configuration, even in the case of incomplete air leak in which the air in the sealed container to be measured gradually leaks, it is possible to detect the amount of pressure change due to the leak, and reliably and easily prevent incomplete air leaks, particularly small leaks. Can be detected.
[0015]
In order to achieve the above object, in the present invention, in the above-described configuration, the determination unit has a pressure in the measurement tank that changes in a short time after a predetermined time has elapsed after the communication between the measurement tank and a reference pressure chamber. Incomplete air leak of the sealed container to be measured is detected based on the amount of pressure change.
[0016]
Here, the short time after the passage of the predetermined time after the communication is, for example, about 0.1 seconds after the passage of about 0.3 seconds after the communication between the measurement tank and the reference pressure chamber.
[0017]
According to this configuration, even in the case of a middle leak between a large leak and a small leak even among non-perfect leaks, the determination based on the pressure change in the initial stage is performed, so that the determination including the degree of air leak can be made quickly. It becomes possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
[0019]
FIG. 1 is a schematic explanatory diagram illustrating the basic configuration concept of an air leak detection device 10 of the present embodiment. An air leak detection device 10 includes a measurement tank 14 that houses and measures a sealed container to be measured, for example, a seal relay (hereinafter referred to as a workpiece) 12 that is a microelectronic component, and a plurality of switching valves as a communication switching mechanism for the measurement tank 14. (In this embodiment, the pressure reducing device 16 connected via four switching valves Va, Vb, Vc, Vd) and the pressure inside the measuring tank 14 can be detected in the vicinity of the measuring tank 14. A pressure sensor 18, a pressure reducing device 16, a pressure sensor 18, and a control unit 20 including a determination unit that performs calculation related to control and detection values of the switching valves Va, Vb, Vc, Vd and the like and performs predetermined determination output. Has been.
[0020]
The measurement tank 14 is an openable and closable case composed of, for example, an upper casing 14a and a lower casing 14b connected by a hinge or the like, and the upper casing 14a and the lower casing 14b are joined (closed state). Thus, a measurement chamber 22 for accommodating the workpiece 12 is formed in a substantially central portion. Around the measurement chamber 22, for example, an O-ring 24 is arranged as an airtight seal member in order to ensure airtightness of the measurement chamber 22 in the closed state. Therefore, the measurement chamber 22 having a substantially sealed space with a predetermined volume can be formed by the upper housing 14a and the lower housing 14b. In the measurement chamber 22, the entire upper wall 14a and lower housing 14b or the inner wall surface is formed of metal, hard resin, or the like so that the inner wall surface is not deformed by a pressure change or the like.
[0021]
On the other hand, the decompression device 16 is constituted by a decompression tank 16c having a vacuum pump 16a and a regulator 16b so that the inside of the decompression tank 16c can always be maintained at a predetermined pressure. The switching valves Va, Vb, and Vd selectively open and close the flow path 26 that connects the measurement tank 14 and the pressure reducing device 16 to each other. In particular, the space formed between the switching valve Va and the switching valve Vb defines a reference pressure chamber 28 that can form different pressure states with respect to the measurement tank 14. The switching valve Vc is a valve for opening to the atmosphere, and is opened when the pressure of the flow path 26 and the measurement chamber 22 of the measuring tank 14 is released to the atmosphere.
[0022]
A characteristic matter of this embodiment is that the pressure inside the measurement tank 14 is changed by selectively communicating the measurement tank 14 with the reference pressure chamber 28 having a different internal pressure, and the pressure at that time. According to the change state, it is determined whether or not there is an air leak in the work 12 stored in the measurement tank 14. That is, the internal space 12a of the work 12 is independent or assimilated with the remaining space 22a of the measurement tank 14 (the internal space of the measurement tank 14 excluding the volume of the work 12) due to complete or incomplete sealing of the work 12. As a result, the substantial residual space (residual volume) of the measurement tank 14 varies, and the ultimate pressure at the time of communication between the measurement tank 14 and the reference pressure chamber 28 varies. The presence / absence of air leak is determined based on this fluctuation. In FIG. 1, when the workpiece 12 is arranged in the measurement chamber 22, the remaining space 22 a of the measurement chamber 22 is drawn relatively large. However, in actuality, the volume of the measurement chamber 22 is slightly smaller than the volume of the workpiece 12. Only by increasing the size, the amount of fluctuation of the space in the measurement tank 14 due to assimilation of the internal space 12a of the work 12 appears remarkably. For example, when the internal space 12a of the workpiece 12 is 0.1 cc, the remaining space 22a of the measurement chamber 22 is set to 1.5 cc, and the capacity of the reference pressure chamber 28 at this time is set to 0.8 cc, for example.
[0023]
The operation of the air leak detection device 10 of FIG. 1 will be described using the operation table of the switching valves Va, Vb, Vc, Vd shown in FIG. 2 and the pressure change diagram of the measurement chamber 22 of the measurement tank 14 shown in FIG. In the present embodiment, the atmospheric pressure is assumed to be constant.
[0024]
First, as a determination preparation, the determination target workpiece 12 is put into the measurement chamber 22 of the measurement tank 14. At this time, the control unit 20 opens only the switching valves Va and Vb (timing T1). Accordingly, the reference pressure chamber 28 defined by the measurement tank 14 and the switching valves Va and Vb communicates with each other. Subsequently, the upper housing 14a and the lower housing 14b of the measurement tank 14 are brought into close contact (lid closing operation), and the measurement tank 14 is substantially sealed. Since the internal pressure of the space including the measurement chamber 22 increases due to the lid closing operation, the control unit 20 opens the switching valve Vc following the switching valves Va and Vb, and the measurement chamber 22 and the reference pressure chamber 28. Is set to atmospheric pressure (P0 = 1013 × 10 ² Pa) (timing T2). Next, the switching valves Va and Vc are closed and the switching valve Vd is opened (timing T3). By this operation, the space including the reference pressure chamber 28 is connected to the decompression device 16 and controlled by the decompression device 16. At this time, the decompression device 16 decompresses the pressure to, for example, PV = 0.4 kgf / cm ² (392 × 10 ² Pa). In this state, the switching valves Vb and Vd are closed. That is, all the switching valves are closed to form the reference pressure chamber 28 having a predetermined volume (0.8 cc) of the reference pressure state value P1 (negative pressure state reduced by 392 × 10 ² Pa from atmospheric pressure), and the control unit 20 completes measurement preparation (timing T4).
[0025]
When the measurement start signal is given to the control unit 20, the control unit 20 opens only the switching valve Va (timing T5), and connects the measurement tank 14 (measurement chamber 22) and the reference pressure chamber 28 to the measurement tank 14 ( The internal pressure of the measurement chamber 22) is changed (depressurized).
[0026]
The control unit 20 controls the pressure sensor 18 with only the switching valve Va opened, and the elapsed time B (0.3 seconds after opening the switching valve Va) and elapsed time C (0 after opening the switching valve Va). Measure the pressure (for example, PXa, PXb) in the measurement chamber 22 at the time of 4 seconds (see FIG. 3). Subsequently, the control unit 20 opens the switching valves Va, Vb, and Vd for a predetermined time (for example, between elapsed times C and D ; 0.4 seconds), and the measurement chamber 22 is in the initial reference pressure state of the reference pressure chamber 28. The pressure is reduced to the value P1 (timing T6), the switching valve Va is closed (timing T7), and after a predetermined time (for example, 3 seconds), the pressure (for example, PXd) in the measurement chamber 22 is measured. At this time, when there is no air leak in the workpiece 12, the measured value of the pressure sensor 18 in the measurement chamber 22 is PXd = PV. Further, the control unit 20 measures the pressure (for example, PXc) in the measurement chamber 22 for a predetermined time (for example, 2 seconds) after measuring PXd, and ends the pressure measurement for air leak determination.
[0027]
Subsequently, the control unit 20 starts an air leak determination process. By the way, the following relationship is established between the measurement chamber 22 of the measurement tank 14 and the reference pressure chamber 28 by Boyle Charles' law.
[0028]
[Expression 1]

At this time, since P1 = P0−PV and P2 = P0−PX,
[Expression 2]

It becomes. It is assumed that the gas temperature changes when the measurement chamber 22 and the reference pressure chamber 28 are connected, but is stable and does not change after a predetermined time.
[0029]
Therefore, the pressure PX (PXa) of the measurement chamber 22 and the reference pressure state value PV (PXd) of the reference pressure chamber 28 measured at the elapsed time C are the reference volume V1 of the reference pressure chamber and the reference volume V1. 12 can be associated with a fixed value defined by the total volume obtained by adding the remaining volume V2 of the measuring tank 14 when 12 is stored. When there is no air leak in the workpiece 12, that is, when the workpiece 12 is a “good product” that is completely sealed, measurement is performed after the reference pressure state value PV of the reference pressure chamber, the reference pressure chamber 28, and the measurement tank 14 are communicated. The value defined by the tank pressure value PX (PXa) of the measurement tank 14 to be coincided with the value defined by the volume V1 of the measurement tank 14 and the volume V2 of the reference pressure chamber 28 when there is no air leak. It will be. For example, when V1 = 0.8 cc and V2 = 1.5 cc, the value of PX / PV is V1 / (V1 + V2) = 0.8 / 2.3 = 0.3478. On the other hand, when the workpiece 12 is a “complete leak product (large leak)” that has completely leaked, V1 / (V1 + V2) = 0.8 / 2.4 = 0.3333. Therefore, when a non-air leaking non-defective product is stored, a fixed ratio V1 / (V1 + V2) defined by the volume of the measurement tank 14 and the reference pressure chamber 28 is used as a criterion, and the reference pressure state value PV of the corresponding reference pressure chamber By determining the variation ratio between (PXd) and the pressure value PX (PXa) in the measurement tank 14 measured after communicating with the measurement tank 14, it is determined whether the product is “good” or “completely leaked” Can do. In order to make a strict determination, it is preferable to use a value of V1 / (V1 + V2) = 0.3478 as a determination value. However, taking a measurement error into consideration, a determination value for determining a non-defective product is, for example, 0. .., 3400, a practical large leak can be determined satisfactorily. Since PV and PX are measured almost at the same time, the atmospheric pressure at the time of measurement can be considered to be substantially constant, so that the determination can be made satisfactorily.
[0030]
In FIG. 3, the work 12 that has caused a pressure change (solid line A in the figure) and a complete air leak (large leak) when the non-defective work 12 is stored in the measurement tank 14 is stored in the measurement tank 14. The pressure change when the measurement is performed (broken line B in the figure) is shown. From the figure, it can be seen that when a large leak occurs, the pressure reduction rate decreases because the substantial volume in the measuring tank 14 increases. In FIG. 3, the pressure temporarily decreased after the elapsed time A-C and then increased again when the air was rapidly depressurized and the air was rapidly cooled (adiabatic expansion). The air takes away the surrounding heat and returns to room temperature. This temperature change causes a pressure change. As a result, a temporary pressure drop as described above occurs. In the present embodiment, when a large leak occurs, the inside of the measurement tank 14 is reduced to the initial pressure of the reference pressure chamber 28 after the elapsed time C, so that the pressure change is the same as that of the non-defective product.
[0031]
Thus, the fixed ratio defined by the volume of the measurement tank 14 and the reference pressure chamber 28, the pressure in the measurement tank 14 measured after the measurement tank 14 and the reference pressure chamber 28 are communicated, and the sealed container to be measured are stored. The presence or absence of a large leak is determined quickly and accurately by comparing the fluctuation ratio defined by the pressure in the measurement tank after a predetermined time has elapsed after the measured pressure tank is set to the reference pressure state value of the reference pressure chamber. Can do.
[0032]
Subsequently, the control unit 20 detects the presence or absence of an incomplete leak, that is, a small leak in which the air in the work 12 leaks little by little. In the case of a small leak, since the leak amount is very small, even if the measurement tank 14 and the reference pressure chamber 28 are communicated and the pressure in the measurement chamber 22 is changed, the pressure change immediately after the communication is the same as the non-defective product. Show. Therefore, the control unit 20 closes the switching valve Va at timing T7, and measures the pressure (PXd) in the measurement chamber 22 measured after a predetermined time (for example, 3 seconds; elapsed time E) and the predetermined time (after the PXd measurement). For example, using the pressure (PXc) of the measurement chamber 22 at 2 seconds; elapsed time F), the amount of pressure change after a predetermined time in the sealed measurement tank 14 is measured. When a small leak has occurred, the internal pressure of the measuring tank 14 gradually increases due to air leak, so the rate of change differs from that of a non-defective product (the pressure change at the time of the small leak is shown by three points in FIG. (Indicated by chain line C). Appropriate even when a small leak occurs by measuring the pressure change (flowering time EF) after a predetermined time after reducing the internal pressure of the measuring tank 14 and comparing it with the pressure change in the case of a non-defective product. Leakage determination can be performed. In addition, after the pressure in the measurement tank 14 falls rapidly once by the elapsed time CF in FIG. 3, it is rising gradually. This is also due to the adiabatic expansion described above, and a slight pressure change occurs even in the case of the non-defective workpiece 12. If there is a small leak, the rate of change increases by the amount of air leak.
[0033]
Furthermore, in the air leak of the work 12, there is a case where the above-described air leak between the large leak and the small leak, that is, a so-called medium leak occurs. In this case, as indicated by the alternate long and short dash line D in FIG. 3, the middle leak is completed by, for example, the elapsed time DE in FIG. As a result, only the pressure change due to adiabatic expansion, that is, the same pressure change as the non-defective product (solid line A in FIG. 3) is shown between the elapsed times EF for judging small leaks, and appropriate leak judgment can be performed. Disappear. On the other hand, as shown in FIG. 3, since the values of PX / PV at the elapsed times C and E for determining a large leak both increase, the fluctuation with respect to the fixed ratio (volume ratio) defined by V1 / (V1 + V2). The determination by the ratio (pressure ratio) cannot be performed (there may be a non-defective product). Therefore, in order to determine the middle leak, attention is paid to the pressure change immediately after the measurement tank 14 and the reference pressure chamber 28 are communicated (elapsed time BC; for example, 0.1 s). As shown in FIG. 3, when a middle leak occurs, the internal pressure of the measurement tank 14 increases due to air leaks even during the elapsed time B-C as compared with a non-defective product. The presence of medium leak is determined by comparing the pressure change rate in a short time with the pressure change rate in the case of a non-defective product.
[0034]
As described above, the control unit is configured to observe the pressure change in the measurement tank 14 by selectively connecting the reference measurement chamber 28 having a predetermined reference volume and a reference pressure state value to the measurement tank 14. No. 20 can determine all air leaks such as large leaks, medium leaks, and small leaks in an easily distinguishable manner. The results are, for example, “good”, “large leak”, “medium leak”, “small leak”. Is output as follows. At this time, since the measurement tank 14 and the reference pressure chamber 28 are connected and only the pressure change is measured, the presence / absence of complete leak and incomplete leak can be determined quickly and accurately with an easy configuration.
[0035]
In this embodiment, the example in which the reference pressure chamber 28 is depressurized has been described. However, the same determination can be made even when the reference pressure chamber 28 is in a pressurized state and the pressure in the measurement tank 14 is changed. . In the present embodiment, the measurement tank 14 is set to atmospheric pressure. However, if the pressure is different from that of the reference pressure chamber 28, the same effect as that of the present embodiment can be obtained in a reduced pressure state or a pressurized state.
[0036]
【The invention's effect】
According to the present invention, when there is an air leak in the sealed container to be measured, the internal space of the measured sealed container is assimilated with the internal space of the measurement tank, and the substantial internal volume increases. After reaching the chamber, the pressure reached by the measuring tank rises (when the reference pressure chamber is depressurized with respect to the measuring tank) or descends (when the reference pressure chamber is pressurized with respect to the measuring tank) when there is no air leak If you do). It is possible to accurately determine the presence or absence of air leak based on this pressure change. At this time, since it is not necessary to stabilize the pressure in the measurement tank for measurement preparation, it is possible to make a quick determination with an easy configuration in which the measurement tank and the reference pressure chamber communicate with each other.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a configuration concept of an air leak detection device according to an embodiment of the present invention.
FIG. 2 is an explanatory timing diagram showing the operation timing of the switching valve of the air leak detection device according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram for explaining a pressure change when each air leak occurs when the air leak detection device according to the embodiment of the present invention is used.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Air leak detection apparatus, 12 Workpieces, 12a Internal space, 14 Measurement tank, 14a Upper housing | casing, 14b Lower housing | casing, 16 Pressure reducing device, 18 Pressure sensor, 20 Control part, 22 Measurement chamber, 22a Residual space, 24 O-ring, 26 flow path, 28 reference pressure chamber, Va, Vb, Vc, Vd switching valve.

Claims

A measurement tank (14) capable of forming a sealed space of a predetermined volume capable of storing the sealed container (12) to be measured;
Reference pressure chamber to have a reference volume (V1) and (28),
A decompression device (16);
A switching valve which permits the measuring Joso (14) the reference pressure chamber selective communication (28) (Va),
A switching valve (Vb) that allows selective communication between the reference pressure chamber (28) and the pressure reducing device (16);
A pressure sensor (18) for measuring the pressure in the measuring Joso (14),
A determination unit for determining the presence or absence of an air leak in the sealed container (12) to be measured;
In an air leak detection method for a sealed container using an air leak detection device including :
Bringing the measuring tank (14) and the reference pressure chamber (28) to atmospheric pressure;
The switching valve (Va) is closed to cut off the communication between the measuring tank (14) and the reference pressure chamber (28), and the switching valve (Vb) is opened to connect the reference pressure chamber (28) and the pressure reducing device (16). Communicating and depressurizing the reference pressure chamber (28) to a reference pressure state by the decompression device (16);
After the switching valve (Vb) is closed and the communication between the reference pressure chamber (28) and the pressure reducing device (16) is shut off, the switching valve (Va) is opened and the measurement tank (14), the reference pressure chamber (28), And mixing the gas in the measurement tank (14) and the gas in the reference pressure chamber (28);
Measuring the pressure value (Px) in the tank of the mixed gas with the pressure sensor (18);
The switching valve (Va) and the switching valve (Vb) are opened, and the measurement tank (14), the reference pressure chamber (28), and the decompression device (16) are communicated with each other, and the measurement tank (14 ) To a reference pressure state and then closing the switching valve (Va);
Measuring a reference pressure state value (Pv) in the measurement tank (14) with a pressure sensor (18);
When the variation ratio defined by the pressure value in the tank (Px) and the reference pressure state value (Pv) is the left side, the reference volume (V1) of the reference pressure chamber (28) and the reference sealed container without air leak are stored Based on the expression Px / Pv = V1 / (V1 + V2) with a fixed ratio defined by the total volume obtained by adding the reference volume (V1) to the remaining volume (V2) of the measurement tank (14) Determining a complete air leak in the measured sealed container (12);
An air leak detection method for an airtight container, comprising:

In the air leak detection method of the airtight container according to claim 1,
The determination unit measures the pressure in the measurement tank for a predetermined time from the communication between the measurement tank (14) and the reference pressure chamber (28), and is an air leak of the measured sealed container (12) based on the pressure change amount, An air leak detection method for an airtight container, characterized by detecting an air leak that is smaller than a complete air leak.

The detection method according to claim 1,
The determination unit determines whether the measured sealed container (12) is based on the pressure change amount of the pressure in the measurement tank that changes in a short time after the passage of a predetermined time after the communication between the measurement tank (14) and the reference pressure chamber (28). An air leak detection method for an airtight container, characterized by detecting an air leak that is smaller than a complete air leak.