JP3461973B2 - Pressure leak measurement method - Google Patents
Pressure leak measurement methodInfo
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- JP3461973B2 JP3461973B2 JP14768495A JP14768495A JP3461973B2 JP 3461973 B2 JP3461973 B2 JP 3461973B2 JP 14768495 A JP14768495 A JP 14768495A JP 14768495 A JP14768495 A JP 14768495A JP 3461973 B2 JP3461973 B2 JP 3461973B2
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Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】この発明は、被測定物内に加圧気
体源から加圧気体を導入して、被測定物内の圧力変化を
測定することによって、被測定物からの圧力洩れを測定
する圧力洩れ測定方法に関する。
【０００２】
【従来の技術】自動車エンジン用鋳造ブロック等の密閉
性を測定するために、被測定物の内部にエアコンプレッ
サ等の加圧気体源から圧縮空気等の加圧気体を導入し
て、被測定物からの圧力洩れを測定する方法が用いられ
る。この際、単に圧力センサによって被測定物からの圧
力洩れに伴う気圧の絶対値の変化を測定する方式では、
圧力センサの測定精度の制約があるため精度の良い圧力
洩れ測定ができない。そこで、高精度の圧力洩れ測定を
行うための装置として、被測定物とは独立した密閉空間
である測定用マスタ（以下、単に「マスタ」ともい
う。）を用意して、このマスタと被測定物とを差圧検出
器を介して接続し、差圧の変化を検出することによって
被測定物からの圧力洩れを測定する方法が開発されてい
る。かかる差圧測定による圧力洩れ測定方法の具体例と
しては、例えば、特開平４−２２１７３３号公報に記載
された圧力洩れ測定装置の発明がある。この公報に記載
された技術においては、被測定物とほぼ同一形状・同一
容積の測定用マスタと被測定物とが差圧検出器を介して
接続されている。そして、被測定物及びマスタ内に圧縮
空気が導入されて測定圧力に達した時点から差圧値の経
時変化を測定することによって、被測定物からの圧力洩
れの測定が行われる。
【０００３】また、被測定物とほぼ同一形状・同一容積
の測定用マスタを用いる代わりに、配管の一部を密閉し
て、この密閉部分と被測定物との差圧を比較することに
よって、圧力洩れの測定を行う方法も開発されている。
かかる圧力洩れ測定方法においては、マスタとして配管
の一部を密閉して、この密閉配管内の圧力と被測定物内
の圧力とを比較する方式を採っている。すなわち、密閉
される配管部分と被測定物とが差圧検出器を介して接続
されている。そして、被測定物及び密閉配管部分に圧縮
空気が導入されて測定圧力に達した時点から差圧値の経
時変化を測定することによって、被測定物からの圧力洩
れの測定が行われる。
【０００４】
【発明が解決しようとする課題】しかしながら、いずれ
の圧力洩れ測定方法においても、被測定物及び被測定物
とは独立した密閉空間であるマスタ内に圧縮空気が導入
される際の断熱圧縮に起因する温度変化等によって圧力
変動が生ずるため、差圧値の時間当たりの変化量から圧
力洩れ量を算出するためには、圧力が安定するまで待た
ねばならない。この点について、図３及び図４を参照し
て説明する。図３は、マスタを使用する圧力洩れ測定に
おける被測定物内の圧力と差圧の変化を示すグラフであ
る。被測定物内の圧力は圧力センサで測定され、差圧は
差圧センサで測定される。図３に示されるように、加圧
段階Ｔ１においては、最初に測定圧力より高圧に調節さ
れた圧縮空気が被測定物及びマスタに供給され、続いて
測定圧力に調節された圧縮空気が供給されるため、圧力
値は一旦測定圧力を越えた後に測定圧力まで下がって安
定する。続く平衡段階Ｔ２では、時刻ｔ２において電磁
弁が切り替えられて被測定物とマスタとが遮断されるの
に伴って、図３に示されるようにプラスの差圧が一時的
に発生する。その後、断熱圧縮に起因する温度変化等に
よって圧力変動が生じ、図３に示される被測定物内の圧
力が測定圧力から次第に低下していく。そして、時刻ｔ
４で、断熱圧縮に起因する温度変化等が収まるため、ほ
ぼ一定の圧力値に安定する。このように、断熱圧縮に起
因する温度変化等によって、圧力が一定の値に落ちつく
まである程度の時間を要している。なお、この被測定物
内の圧力は、圧力洩れがない場合のものを示している。
【０００５】この圧力変動に伴って、時刻ｔ２において
一旦プラスになった差圧も次第に減少していく。そし
て、実線で示される圧力洩れがない場合の差圧は、時刻
ｔ４において、圧力と同様にほぼ一定の値に安定する。
また、図３に示される差圧のうち破線で示されるのは圧
力洩れがある場合であり、一点鎖線で示されるのは微小
な圧力洩れがある場合であるが、これらの値も同様に、
時刻ｔ２から時刻ｔ４の間においては非直線的に変動し
ている。そして、時刻ｔ４において、これらの圧力洩れ
がある場合の差圧の変化は直線的なものとなり、時間当
たりの変化量は一定となる。そして、検出段階Ｔ３にお
いては、圧力洩れがない場合の被測定物内の圧力は、時
刻ｔ４において安定した一定の値に保たれる。従って、
差圧センサの測定値も、実線で示されるように一定の値
に保たれ、この場合には被測定物からの圧力洩れはない
ものと判定される。一方、圧力洩れがある場合には、差
圧センサの測定値は破線あるいは一点鎖線で示されるよ
うに、一定の値とならずに変化し続ける。但し、この変
化は直線的なものであるため、その変化率から被測定物
からの圧力洩れ量を求めることができる。
【０００６】また、図４に示されるように、加圧条件の
相違によっても、差圧変化の様子は異なってくる。図４
は、圧力洩れがない被測定物についての、三種類の異な
る加圧条件における差圧変化の様子を示すグラフであ
る。図４に示されるように、加圧条件１においては比較
的短時間で断熱圧縮等に起因する被測定物内の圧力変動
がなくなって差圧が安定しているが、加圧条件２ではこ
の不安定な時間が長くなり、加圧条件３では差圧が安定
するまでにさらに長時間を要している。このように、加
圧条件によって圧力変動がなくなるまでの時間がばらつ
くため、実際に圧力変動がなくなる時点よりもかなり後
の時点ｔ１２まで待ってから、差圧の測定値を用いた圧
力洩れ量の算出が行われていた。図３の検出期間Ｔ３の
開始時点ｔ１０も、同様に実際に圧力変動がなくなる時
点ｔ４よりも後の時点として決められていた。すなわ
ち、被測定物の内圧が確実に安定した状態で測定を行う
必要から、実際に被測定物内の圧力変動がなくなるのに
必要な時間に加えてさらに余分な時間の経過を待ってか
ら測定を行わざるを得なかったのである。このように、
被測定物及びマスタ内に圧縮空気が導入される際の温度
変化等による圧力変動がなくなって圧力が確実に安定す
るまで待たなければならないため、測定時間の短縮に限
界があるという問題点があった。
【０００７】そこで、本出願の請求項１に係る発明にお
いては、圧力が安定する時点を正確に求めることによっ
て、測定時間を短縮することができる圧力洩れ測定方法
を提供することを目的とする。
【０００８】
【課題を解決するための手段】そこで、上記の課題を解
決するために、請求項１に係る発明においては、被測定
物と該被測定物とは独立した密閉空間とに加圧気体を導
入し、所定時間後の前記被測定物と前記独立した密閉空
間との差圧を検出することによって前記被測定物からの
圧力洩れを測定する圧力洩れ測定方法であって、前記差
圧の検出値に基づき該差圧の単位時間当たりの変化量が
一定となる時点を求め、その時点から前記被測定物から
の圧力洩れの測定を行うことを特徴とする圧力洩れ測定
方法を創出した。ここで「加圧気体」とは、圧縮空気を
始めとして圧縮窒素ガス、圧縮酸素ガス、圧縮アルゴン
ガス等の種々の気体を含むものである。
【０００９】
【作用】さて、請求項１の発明に係る圧力洩れ測定方法
は、加圧気体が導入された被測定物と独立した密閉空間
との差圧を検出することによって、被測定物からの圧力
洩れを測定する方法である。ここで、被測定物と独立し
た密閉空間との間の差圧の検出値に基づき、該差圧の単
位時間当たりの変化量が一定となる時点を求め、その時
点から被測定物からの圧力洩れの測定を行う方式を採用
している。従って、圧力が安定する時点が正確に求めら
れ、その時点から直ちに差圧の測定値を用いた圧力洩れ
の大きさの測定を行うことができるため、余分な待ち時
間を省くことができ、短時間で圧力洩れ測定を行うこと
ができる。このようにして、圧力が安定する時点を正確
に求めることによって、測定時間を短縮することができ
る圧力洩れ測定方法となる。
【００１０】
【実施例】次に、本発明を具現化した一実施例につい
て、図１及び図２を参照して説明する。まず、本実施例
の圧力洩れ測定方法による具体的な測定結果について、
図１を参照して説明する。図１は、本実施例の圧力洩れ
測定方法による測定における差圧の変化を示すグラフで
ある。図１に示されるように、電磁弁が切り替えられて
被測定物とマスタとが遮断されるのに伴って発生した差
圧が、圧力変動を伴いながら次第に変化していく。ここ
で、断熱圧縮等に起因して実際に被測定物の内圧が変動
するのは期間ΔＴ２の範囲であり、この範囲ΔＴ２にお
いては被測定物からの圧力洩れに起因する差圧ΔＰに、
圧力変動に起因する差圧ΔＰ０が加わった値が差圧値と
して検出される。範囲ΔＴ２の終了する点ＭＰ４以降に
おいては、被測定物からの圧力洩れに起因する差圧ΔＰ
のみが差圧値として検出される。すなわち、点ＭＰ４以
降においては差圧値の経時変化を用いて被測定物からの
圧力洩れ量を算出することが可能となる。従って、点Ｍ
Ｐ４を正確に求めてこの時点から測定を始めることによ
って、最も短時間で測定を行うことができる。
【００１１】この点ＭＰ４は、被測定物からの圧力洩れ
のあるなしに関わらず、差圧の単位時間当たりの変化量
が一定になる点、すなわち差圧センサによる差圧の測定
値が描く曲線の二回微分値が零になる点として求めるこ
とができる。本実施例においては、差圧の単位時間当た
りの変化量が一定になる点を求めるに当たって、差圧セ
ンサによる測定値そのものではなく、その移動平均値を
用いている。これは、測定データのばらつきによる誤差
をなくするためである。具体的には、差圧センサからの
測定信号が、予め設定されたサンプリング時間ごとに測
定値Ｘとして取り込まれる。この測定値Ｘの移動平均算
出個数ＮP ごとに移動平均値Ｐが算出され、算出された
移動平均値Ｐが検出値ＸP として取り込まれる。この検
出値ＸP を用いて、予め設定された変化量算出単位時間
Ｃ１ごとに、一回微分値Ｄ１が次式（１）によって算出
される。
Ｄ１(N) ＝ＸP(N)−ＸP(N-C1) …（１）
そして、二回微分値Ｄ２が次式（２）によって算出され
る。
Ｄ２(N) ＝Ｄ１(N) −Ｄ１(N-C1) …（２）
【００１２】さらに、加重移動平均法によって、二回微
分値Ｄ２から加重平均値Ｄ２AVE を算出して、この加重
平均値Ｄ２AVE が零になる点をもって、点ＭＰ４として
いる。このようにして点ＭＰ４に到達したことが判別さ
れたら、その時点から差圧の測定値の時間当たりの変化
量を用いて被測定物の圧力洩れ量ＶL が算出される。こ
の算出の具体的な方法としては、種々の方法を用いるこ
とができる。例えば、点ＭＰ４ともう一点の二点間の差
圧測定値Ｘあるいは検出値ＸP から求める方法、単位時
間の移動平均による方法、単位時間当たりの変化量（例
えば、一回微分値Ｄ１）の移動平均による方法等であ
る。以上のようにして、圧力変動がなくなる時点ＭＰ４
を正確に求め、その時点から圧力洩れ量の算出を開始す
ることによって、従来の検出開始時点ＭＰ３よりも早く
検出を開始することができる。これによって、従来の検
出期間Ｔ３よりも早い検出期間Ｔ４で圧力洩れ量を算出
することができ、圧力洩れの測定時間を短縮することが
できる。
【００１３】次に、本実施例の圧力洩れ測定方法の測定
手順について図２を参照して説明する。図２は、本実施
例の圧力洩れ測定方法の測定手順を示すフローチャート
である。図２のステップＳ１０で測定が開始されると、
まず、被測定物及びマスタについてのパラメータが入力
される（ステップＳ１２）。パラメータとしては、被測
定物の大きさ，形状等、マスタの大きさ，形状等があ
る。次に、差圧センサによる差圧の測定値Ｘが入力され
る（ステップＳ１４）。続いて、移動平均Ｐを算出して
良いか否かの判定が行われる（ステップＳ１６）。測定
値Ｘが移動平均算出に必要な個数ＮP だけ入力されるま
ではこの判定はＹＥＳにならず、ステップＳ１４に戻っ
て測定値Ｘの入力が繰り返される。測定値Ｘが移動平均
算出に必要な個数ＮP だけ入力された時点でステップＳ
１８へ進んで、移動平均Ｐが算出される。こうして算出
された移動平均Ｐの値が、検出値ＸP として入力される
（ステップＳ２０）。
【００１４】次に、変化量を演算して良いか否かの判定
が行われる（ステップＳ２２）。予め設定された変化量
算出単位時間Ｃ１の時間が経過するとこの判定はＹＥＳ
となり、検出値ＸP を用いて上記の式（１）及び式
（２）に従って、一回微分値Ｄ１及び二回微分値Ｄ２が
算出される（ステップＳ２４）。続いて、加重平均値Ｄ
２AVE を算出して良いか否かの判定が行われる（ステッ
プＳ２６）。二回微分値Ｄ２が移動加重平均算出に必要
な個数だけ算出されるまではこの判定はＹＥＳになら
ず、ステップＳ１４に戻って上述した工程が繰り返され
る。二回微分値Ｄ２が移動加重平均算出に必要な個数だ
け算出された時点でステップＳ２８へ進んで、加重平均
値Ｄ２AVE が算出される。こうして算出された加重平均
値Ｄ２AVE が零であるか否かによって、圧力が安定した
か否かの判断が行われる（ステップＳ３０）。加重平均
値Ｄ２AVE が零であればこの判定はＹＥＳとなり、ステ
ップＳ３２の判定もＹＥＳとなって、圧力洩れ量ＶL の
算出が行われる（ステップＳ３４）。これによって、圧
力洩れの測定手順は終了する（ステップＳ３６）。
【００１５】本実施例においては、演算処理に当たって
移動平均法や加重平均法を用いているが、必ずしもこれ
らの算出方法に限られるものではない。また、本実施例
の測定方法は、配管の一部を密閉して独立空間とする等
の他の方式に適用することもできる。圧力洩れ測定方法
のその他の工程の内容についても、本実施例に限定され
るものではない。
【００１６】
【発明の効果】請求項１に係る発明においては、差圧の
単位時間当たりの変化量が一定となる時点を求め、その
時点から前記被測定物からの圧力洩れの測定を行う圧力
洩れ測定方法を創出したために、圧力が安定する時点が
正確に求められ、その時点から差圧の測定値を用いた圧
力洩れの大きさの測定を行うことができ、余分な待ち時
間を省くことができる。これによって、圧力洩れの測定
時間を短縮することができる、極めて実用的な圧力洩れ
測定方法となる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a change in pressure in a measured object by introducing a pressurized gas from a pressurized gas source into the measured object. The present invention relates to a pressure leak measuring method for measuring pressure leak from an object to be measured. 2. Description of the Related Art A pressurized gas such as compressed air is introduced from a pressurized gas source such as an air compressor into an object to be measured in order to measure the hermeticity of a casting block for an automobile engine or the like. A method of measuring pressure leak from an object to be measured is used. At this time, in the method of simply measuring the change in the absolute value of the atmospheric pressure due to pressure leak from the measured object by the pressure sensor,
Due to the limitation of the measurement accuracy of the pressure sensor, accurate pressure leak measurement cannot be performed. Therefore, as a device for performing high-precision pressure leak measurement, a measurement master (hereinafter, also simply referred to as “master”), which is a closed space independent of an object to be measured, is prepared. A method has been developed in which an object is connected via a differential pressure detector and a change in the differential pressure is detected to measure a pressure leak from the object to be measured. As a specific example of such a pressure leak measuring method by differential pressure measurement, there is, for example, an invention of a pressure leak measuring device described in Japanese Patent Application Laid-Open No. Hei 4-221733. In the technique described in this publication, a measurement master having substantially the same shape and the same volume as an object to be measured is connected to the object to be measured via a differential pressure detector. Then, by measuring the change over time of the differential pressure value from the time when the compressed air is introduced into the measured object and the master to reach the measured pressure, the pressure leak from the measured object is measured. In addition, instead of using a measurement master having substantially the same shape and the same volume as an object to be measured, a part of a pipe is sealed and a differential pressure between the sealed portion and the object to be measured is compared. Methods for measuring pressure leaks have also been developed.
In such a pressure leak measuring method, a method is adopted in which a part of a pipe is sealed as a master, and the pressure in the sealed pipe is compared with the pressure in an object to be measured. That is, the pipe portion to be hermetically sealed and the object to be measured are connected via the differential pressure detector. Then, the pressure leak from the measured object is measured by measuring the change with time of the differential pressure value from the point in time when compressed air is introduced into the measured object and the sealed pipe to reach the measured pressure. [0004] However, in any of the pressure leak measuring methods, heat insulation when compressed air is introduced into a master to be measured and a master which is a closed space independent of the target to be measured. Since a pressure change occurs due to a temperature change or the like due to compression, in order to calculate a pressure leak amount from a change amount of the differential pressure value per time, it is necessary to wait until the pressure is stabilized. This will be described with reference to FIGS. FIG. 3 is a graph showing changes in the pressure and the differential pressure in the measured object in the pressure leak measurement using the master. The pressure in the object is measured by a pressure sensor, and the differential pressure is measured by a differential pressure sensor. As shown in FIG. 3, in the pressurizing step T1, first, compressed air adjusted to a pressure higher than the measured pressure is supplied to the DUT and the master, and then compressed air adjusted to the measured pressure is supplied. Therefore, the pressure value once exceeds the measurement pressure and then drops to the measurement pressure and stabilizes. In the subsequent equilibrium stage T2, a positive differential pressure is temporarily generated as shown in FIG. 3 as the solenoid valve is switched at time t2 to shut off the device under test and the master. Thereafter, a pressure change occurs due to a temperature change or the like due to the adiabatic compression, and the pressure in the measured object shown in FIG. 3 gradually decreases from the measured pressure. And time t
In step 4, since a temperature change or the like caused by the adiabatic compression stops, the pressure value is stabilized at a substantially constant value. As described above, it takes a certain amount of time for the pressure to reach a certain value due to a temperature change or the like caused by adiabatic compression. Note that the pressure in the object to be measured is a pressure when there is no pressure leak. [0005] With this pressure fluctuation, the differential pressure once positive at time t2 gradually decreases. The pressure difference indicated by the solid line when there is no pressure leak stabilizes at time t4 to a substantially constant value similarly to the pressure.
Of the differential pressures shown in FIG. 3, the one indicated by a broken line is a case where there is pressure leakage, and the one indicated by a dashed line is a case where there is a minute pressure leak.
It fluctuates non-linearly from time t2 to time t4. Then, at time t4, the change in the differential pressure when these pressure leaks are linear, and the amount of change per time is constant. Then, in the detection stage T3, the pressure in the measured object when there is no pressure leak is kept at a stable and constant value at time t4. Therefore,
The measured value of the differential pressure sensor is also maintained at a constant value as shown by the solid line, and in this case, it is determined that there is no pressure leak from the measured object. On the other hand, when there is a pressure leak, the measured value of the differential pressure sensor continues to change without being a constant value as shown by a broken line or a dashed line. However, since this change is linear, the amount of pressure leak from the measured object can be obtained from the change rate. [0006] Further, as shown in FIG. 4, the state of the differential pressure change also differs depending on the difference in the pressurizing condition. FIG.
5 is a graph showing a state of a differential pressure change of an object to be measured having no pressure leak under three different pressurizing conditions. As shown in FIG. 4, under the pressurizing condition 1, the pressure difference in the object to be measured due to adiabatic compression or the like disappears in a relatively short time, and the differential pressure is stabilized. The unstable time becomes longer, and it takes a longer time until the differential pressure is stabilized under the pressurizing condition 3. As described above, since the time until the pressure fluctuation disappears depending on the pressurization condition, the pressure leak amount using the measured value of the differential pressure should be waited until the time t12 which is considerably longer than the time when the pressure fluctuation actually disappears. Calculation was being performed. Similarly, the start time t10 of the detection period T3 in FIG. 3 is also determined as a time later than the time t4 at which the pressure change actually stops. In other words, since it is necessary to perform measurement in a state where the internal pressure of the DUT is reliably stabilized, the measurement must be performed after waiting for an extra time in addition to the time required for the pressure fluctuation in the DUT to actually disappear. I had to do it. in this way,
Since there is no pressure fluctuation due to temperature change when the compressed air is introduced into the DUT and the master, it is necessary to wait until the pressure stabilizes. Was. It is an object of the invention according to claim 1 of the present application to provide a pressure leak measuring method capable of shortening a measuring time by accurately obtaining a time point at which a pressure is stabilized. Therefore, in order to solve the above-mentioned problems, in the invention according to the first aspect, an object to be measured and a closed space independent of the object to be measured are pressurized. gas was introduced and a pressure leak measuring method for measuring the leakage pressure from the object to be measured by detecting the differential pressure between the sealed space and the independent of the object to be measured after a predetermined time, the difference
Obtains a time point at which the amount of change per unit time of the differential pressure based on the detection value of the pressure is constant, creating a pressure leak measuring method and performing pressure leakage measurements from the object to be measured from that point did. Here, the “pressurized gas” includes various gases such as compressed air, compressed nitrogen gas, compressed oxygen gas, and compressed argon gas. The pressure leak measuring method according to the first aspect of the present invention detects a pressure difference between an object to which a pressurized gas is introduced and an independent closed space, thereby detecting the pressure difference from the object to be measured. This is a method for measuring pressure leakage. Here, independent of the DUT
Based on the detected value of the pressure differential between the enclosed space and obtains the time when the amount of change per unit time of the differential pressure becomes constant, employ a method for measuring the pressure leakage from the object to be measured from that point are doing. Therefore, the time point at which the pressure stabilizes is accurately obtained, and the magnitude of the pressure leak can be measured using the measured value of the differential pressure immediately from that time point. Pressure leak measurement can be performed in time. In this manner, a pressure leak measurement method capable of shortening the measurement time by accurately determining the time point at which the pressure is stabilized is obtained. Next, an embodiment of the present invention will be described with reference to FIGS. First, a specific measurement result by the pressure leak measurement method of the present embodiment,
This will be described with reference to FIG. FIG. 1 is a graph showing a change in differential pressure in measurement by the pressure leak measurement method of the present embodiment. As shown in FIG. 1, the differential pressure generated due to the switching of the solenoid valve to shut off the object to be measured and the master gradually changes with pressure fluctuations. Here, the internal pressure of the measured object actually fluctuates due to adiabatic compression or the like in the range of the period ΔT2. In this range ΔT2, the differential pressure ΔP caused by the pressure leak from the measured object includes:
The value to which the differential pressure ΔP0 due to the pressure fluctuation is added is detected as the differential pressure value. After the end point MP4 of the range ΔT2, the differential pressure ΔP due to pressure leak from the measured object
Only the differential pressure value is detected. That is, after the point MP4, it is possible to calculate the amount of pressure leakage from the measured object using the change over time of the differential pressure value. Therefore, the point M
By measuring P4 accurately and starting measurement from this point, measurement can be performed in the shortest time. This point MP4 is a point at which the amount of change in the differential pressure per unit time is constant regardless of whether or not there is a pressure leak from the measured object, that is, a curve drawn by the measured value of the differential pressure by the differential pressure sensor. Can be obtained as a point at which the twice differential value of becomes zero. In the present embodiment, a moving average value is used for obtaining a point at which the amount of change in the differential pressure per unit time becomes constant, instead of the measurement value itself by the differential pressure sensor. This is to eliminate errors due to variations in measurement data. Specifically, a measurement signal from the differential pressure sensor is taken in as a measurement value X at each preset sampling time. Moving average P for each moving average calculated number N P of the measured values X is calculated, the moving average value P calculated is taken as the detection value X P. Using this detection value X P, each C1 preset change amount calculation unit time, first derivative value D1 is calculated by the following equation (1). D1 (N) = XP (N) -XP (N-C1) (1) Then, the second derivative D2 is calculated by the following equation (2). D2 (N) = D1 (N) -D1 (N-C1) (2) Further, a weighted average D2AVE is calculated from the second derivative D2 by a weighted moving average method, and the weighted average is calculated. A point at which the value D2 AVE becomes zero is defined as a point MP4. When it is determined that the point MP4 has been reached in this way, the pressure leak amount VL of the measured object is calculated from the point in time by using the amount of change per hour of the measured value of the differential pressure. Various methods can be used as a specific method of this calculation. For example, a method of obtaining a differential pressure measurement X or the detection value X P between two points of a point MP4 Another point method by the moving average unit time, the amount of change per unit time (for example, first derivative value D1) For example, a moving average method is used. As described above, the point in time when the pressure fluctuation disappears MP4
Is accurately obtained, and the calculation of the pressure leak amount is started from that time, so that the detection can be started earlier than the conventional detection start time MP3. Thereby, the pressure leak amount can be calculated in the detection period T4 earlier than the conventional detection period T3, and the measurement time of the pressure leak can be shortened. Next, the measuring procedure of the pressure leak measuring method of the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart illustrating a measurement procedure of the pressure leak measurement method according to the present embodiment. When the measurement is started in step S10 of FIG.
First, parameters for the device under test and the master are input (step S12). The parameters include the size and shape of the measured object and the size and shape of the master. Next, the measured value X of the differential pressure by the differential pressure sensor is input (Step S14). Subsequently, it is determined whether or not the moving average P can be calculated (step S16). This determination is to measure X is input by the number N P required moving average calculation not to YES, the input of the measurement X is repeated returning to step S14. At the point in time when the measured values X are inputted by the number N P necessary for calculating the moving average, step S
Proceeding to 18, the moving average P is calculated. The value of the moving average P thus calculated is inputted as a detection value X P (step S20). Next, it is determined whether or not the amount of change may be calculated (step S22). This determination is YES if the preset change amount calculation unit time C1 has elapsed.
The first derivative D1 and the second derivative D2 are calculated using the detected value XP in accordance with the above equations (1) and (2) (step S24). Subsequently, the weighted average value D
It is determined whether 2AVE can be calculated (step S26). This determination is not YES until the second derivative D2 is calculated for the number required for the moving weighted average calculation, and the process returns to step S14 to repeat the above-described steps. When the second derivative D2 has been calculated by the number required for calculating the moving weighted average, the process proceeds to step S28, where the weighted average D2AVE is calculated. It is determined whether the pressure has stabilized based on whether the weighted average value D2 AVE calculated in this way is zero (step S30). If the weighted average value D2 AVE is zero, the determination is YES, the determination in step S32 is also YES, and the pressure leak amount VL is calculated (step S34). Thus, the procedure for measuring pressure leakage ends (step S36). In this embodiment, the moving average method and the weighted average method are used in the arithmetic processing, but the present invention is not necessarily limited to these calculation methods. Further, the measuring method of the present embodiment can be applied to other methods such as sealing a part of a pipe to form an independent space. The contents of the other steps of the pressure leak measuring method are not limited to the present embodiment. According to the first aspect of the present invention, a point in time at which the amount of change in the differential pressure per unit time is constant is determined, and from that point of time, the pressure at which the pressure leak from the object is measured. Since the leak measurement method was created, the point at which the pressure stabilizes can be accurately determined, and from that point, the magnitude of the pressure leak can be measured using the measured value of the differential pressure, eliminating unnecessary waiting time. Can be. This provides a very practical pressure leak measurement method that can reduce the pressure leak measurement time.
【図面の簡単な説明】
【図１】本発明に係る圧力洩れ測定方法の一実施例にお
ける具体的な測定結果を示す図である。
【図２】圧力洩れ測定方法の一実施例における測定の手
順を示す図である。
【図３】従来の圧力洩れ測定方法における具体的な測定
結果を示す図である。
【図４】従来の圧力洩れ測定方法における具体的な測定
結果を示す図である。
【符号の説明】
ＭＰ４ 差圧の単位時間当たりの変化量が一定となる時
点BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing specific measurement results in one embodiment of a pressure leak measuring method according to the present invention. FIG. 2 is a diagram showing a measurement procedure in one embodiment of a pressure leak measurement method. FIG. 3 is a diagram showing specific measurement results in a conventional pressure leak measurement method. FIG. 4 is a diagram showing specific measurement results in a conventional pressure leak measurement method. [Explanation of Signs] MP4 Time at which the amount of change in differential pressure per unit time is constant
───────────────────────────────────────────────────── フロントページの続き (73)特許権者 390019035 株式会社フクダ 東京都練馬区貫井３丁目16番５号 (74)上記３名の代理人 100064344 弁理士 岡田 英彦 （外１名） (72)発明者 堀川 宏 愛知県豊田市トヨタ町１番地 トヨタ自 動車株式会社内 (72)発明者 山川 芳彦 愛知県豊田市堤町東住吉50 豊通エンジ ニアリング株式会社ＰＥ第２部営業技術 課内 (72)発明者 小野田 貴 愛知県豊田市細谷町５丁目16番地 鬼頭 工業株式会社内 (72)発明者 井元 宏行 東京都練馬区貫井３丁目16番５号 株式 会社フクダ内 (56)参考文献 特開 平６−194257（ＪＰ，Ａ) 特開 昭59−15834（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01M 3/26 ──────────────────────────────────────────────────続 き Continued on the front page (73) Patent holder 390019035 Fukuda Co., Ltd. 3-16-5 Nukii, Nerima-ku, Tokyo (74) The above three agents 100064344 Patent Attorney Hidehiko Okada (one outsider) (72) Inventor Hiroshi Horikawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Yoshihiko Yamakawa 50 Higashi Sumiyoshi, Tsutsumimachi, Toyota City, Aichi Prefecture Toyotsu Engineering Co., Ltd. Person Takashi Onoda 5-16 Hosoya-cho, Toyota-shi, Aichi Prefecture Kito Kogyo Co., Ltd. (72) Inventor Hiroyuki Imoto 3-16-5 Nukii, Nerima-ku, Tokyo Fukuda Co., Ltd. (56) References 194257 (JP, A) JP-A-59-15834 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) G01M 3/26
Claims (1)
空間とに加圧気体を導入し、所定時間後の前記被測定物
と前記独立した密閉空間との差圧を検出することによっ
て前記被測定物からの圧力洩れを測定する圧力洩れ測定
方法であって、前記差圧の検出値に基づき該 差圧の単位時間当たりの変
化量が一定となる時点を求め、その時点から前記被測定
物からの圧力洩れの測定を行うことを特徴とする圧力洩
れ測定方法。(57) [Claim 1] A pressurized gas is introduced into an object to be measured and a closed space independent of the object to be measured, and after a predetermined time, the object to be measured and the independent closed space are closed. a pressure leak measuring method for measuring the leakage pressure from the object to be measured by detecting the pressure difference between the space, the amount of change per unit time of the differential pressure based on a detection value of the differential pressure and the constant A method for measuring pressure leaks, comprising: determining a certain time point; and measuring pressure leaks from the measured object from that time point.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14768495A JP3461973B2 (en) | 1995-06-14 | 1995-06-14 | Pressure leak measurement method |
| CN 96102299 CN1080879C (en) | 1995-06-14 | 1996-06-13 | Determinating method for pressure leakage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14768495A JP3461973B2 (en) | 1995-06-14 | 1995-06-14 | Pressure leak measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08338784A JPH08338784A (en) | 1996-12-24 |
| JP3461973B2 true JP3461973B2 (en) | 2003-10-27 |
Family
ID=15435953
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14768495A Expired - Lifetime JP3461973B2 (en) | 1995-06-14 | 1995-06-14 | Pressure leak measurement method |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3461973B2 (en) |
| CN (1) | CN1080879C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104896310A (en) * | 2009-06-11 | 2015-09-09 | 华盛顿大学 | Detecting EVENTS AFFECTING LIQUID FLOW IN A LIQUID DISTRIBUTION SYSTEM |
| US10094095B2 (en) | 2016-11-04 | 2018-10-09 | Phyn, Llc | System and method for leak characterization after shutoff of pressurization source |
| US10352814B2 (en) | 2015-11-10 | 2019-07-16 | Phyn Llc | Water leak detection using pressure sensing |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103808474A (en) * | 2012-11-14 | 2014-05-21 | 广州市特种承压设备检测研究院 | Method for checking sealing performance of safety valve |
| KR101527959B1 (en) * | 2014-01-06 | 2015-06-16 | 한양대학교 산학협력단 | Simulation system of Production well tubing |
| CN104913204B (en) * | 2015-06-15 | 2018-02-13 | 汉威科技集团股份有限公司 | Pipeline gas leak detecting device and its detection method |
-
1995
- 1995-06-14 JP JP14768495A patent/JP3461973B2/en not_active Expired - Lifetime
-
1996
- 1996-06-13 CN CN 96102299 patent/CN1080879C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104896310A (en) * | 2009-06-11 | 2015-09-09 | 华盛顿大学 | Detecting EVENTS AFFECTING LIQUID FLOW IN A LIQUID DISTRIBUTION SYSTEM |
| US9939299B2 (en) | 2009-06-11 | 2018-04-10 | University Of Washington | Sensing events affecting liquid flow in a liquid distribution system |
| CN104896310B (en) * | 2009-06-11 | 2019-01-04 | 华盛顿大学 | The device that the method and apparatus of water flowing and water use in monitoring pipe-line system |
| US11493371B2 (en) | 2009-06-11 | 2022-11-08 | University Of Washington | Sensing events affecting liquid flow in a liquid distribution system |
| US10352814B2 (en) | 2015-11-10 | 2019-07-16 | Phyn Llc | Water leak detection using pressure sensing |
| US10962439B2 (en) | 2015-11-10 | 2021-03-30 | Phyn, Llc | Water leak detection using pressure sensing |
| US11709108B2 (en) | 2015-11-10 | 2023-07-25 | Phyn, Llc | Water leak detection using pressure sensing |
| US10094095B2 (en) | 2016-11-04 | 2018-10-09 | Phyn, Llc | System and method for leak characterization after shutoff of pressurization source |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1080879C (en) | 2002-03-13 |
| JPH08338784A (en) | 1996-12-24 |
| CN1140837A (en) | 1997-01-22 |
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