JP3123352B2 - Leak measurement method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring leaks.

[0002]

2. Description of the Related Art There are a pressure drop method and a differential pressure method as a method for measuring leakage from a product requiring hermeticity. The pressure drop method measures a leak by a pressure drop of a measurement system which is left in an airtight state after applying a predetermined pressure to an object to be measured. In the differential pressure method, leakage is measured by a differential pressure between a master serving as a reference and an object to be measured.

[0003]

However, in the leak measurement method using the pressure change as described above, if the pressure change is increased in order to increase the measurement accuracy, the volume of a pipe, a jig or the like may change. There is a problem that, for example, the test pressure fluctuates, and particularly, a very small leak cannot be measured with high accuracy. Also, Japanese Unexamined Patent Publication No.
In the publication, a leak detection device using a diaphragm is disclosed, but it does not directly measure the leak amount. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a leak measuring method and a leak measuring method capable of measuring a minute leak with high accuracy.

[0004]

Means for Solving the Problems] Leakage measurement method of the present invention described in claim 1 for achieving the above object, the volume change
When the first diaphragm chamber is formed by a diaphragm
In both cases, the leak measurement medium is sealed in the first diaphragm chamber.
Flip rice, the volume change of the first diaphragm chamber is output as the diaphragm displacement, the leakage amount is calculated by calculating means, further, the first across the diaphragm
A second diaphragm formed on the side opposite to the diaphragm chamber
The first diaphragm is also sealed with the leak measurement medium in the chamber.
The front of the ram chamber and the side of the second diaphragm chamber, respectively.
An on-off valve that connects the two diaphragm chambers to the atmosphere
The diaphragm is provided by thermal expansion of the leak measurement medium.
When the ram is displaced to one or more of the specified value,
It is characterized by opening the valve closing .

According to a second aspect of the present invention, there is provided the leak measuring method according to the first aspect , wherein the transmission of the leak amount to the diaphragm is prevented when the leak amount is equal to or more than a predetermined amount. Displacement gauge to protect the diaphragm
Control mechanism , provided on the first diaphragm chamber side.
The on-off valve is provided between the diaphragm and the displacement mechanism.
It is characterized by being provided in .

According to a third aspect of the present invention, there is provided a leak measuring apparatus for mounting an object to be measured, and a fluid forming a leak measuring medium is pressurized and supplied to the object to be measured. Leakage from pressurizing means, a diaphragm type volume meter that outputs a change in the volume of the diaphragm according to the amount of leakage from the object to be measured as a diaphragm displacement amount, and a stabilizer that suppresses the influence of disturbance on the diaphragm type volume meter. It is characterized in that the measuring system is constituted, and a calculating means for calculating the leak amount from the diaphragm displacement amount is provided.

According to a fourth aspect of the present invention, there is provided a leak measuring device according to the third aspect, wherein the leak to the diaphragm type volume meter is measured when a leak amount from the measured object is a predetermined amount or more. It is characterized in that a protection means for preventing transmission of the quantity is provided.

According to a fifth aspect of the present invention, there is provided a leak measuring apparatus according to the fourth aspect, wherein the protection means has a protective film which is displaced in accordance with a leak amount from the object to be measured. In addition, it is a displacement regulating mechanism for regulating displacement of the protective film by a predetermined amount or more.

According to a sixth aspect of the present invention, there is provided a leak measuring apparatus as set forth in the fourth or fifth aspect, wherein the protection means is arranged so that when the leak measuring medium is a liquid, It is characterized by being arranged above the mounting position of the object.

According to a seventh aspect of the present invention, there is provided a leak measuring apparatus according to any one of the third to sixth aspects, wherein the ballast is sufficiently larger than a change in volume of the diaphragm. It is a closed container having a volume.

According to an eighth aspect of the present invention, there is provided a leak measuring apparatus as set forth in any one of the third to seventh aspects, wherein the internal pressure of the leak measuring system is measured and A monitoring means for monitoring a mounting abnormality and an operation abnormality of the protection means is provided.

[0012]

According to the leak measuring method of the present invention, the calculating means directly calculates the leak amount from the measured object based on the output diaphragm displacement amount.
The leak amount can be directly measured not by the pressure change but by the volume change of the diaphragm, so that the measurement can be performed with high accuracy without being affected by the pressure change. Also, Diaph
Open / close valve when the ram is displaced to one side by more than the specified value
The diaphragm expands due to the thermal expansion of the leak measurement medium.
Is displaced to one of them by more than a predetermined value.
Also, move the diaphragm to the original position (before the diaphragm is displaced).
State).

According to the leak measuring method of the present invention, when the leak amount of the object to be measured is equal to or more than a predetermined amount, the transmission of the leak amount is blocked to protect the diaphragm. Therefore, the diaphragm can be moved to its original position while preventing the diaphragm from being broken due to the transmission of the leakage amount exceeding a predetermined amount.
Can be restored.

According to the third aspect of the present invention, the leak measuring medium is pressurized by the pressurizing means and supplied to the object to be measured mounted on the measuring table. As a result, when the leakage measurement medium leaks from the object to be measured, the diaphragm changes in volume according to the leakage amount. This volume change is output as a diaphragm displacement amount, and the amount of leakage is directly calculated by the calculating means. Even if disturbances such as fluctuations in atmospheric pressure or convection in the atmosphere occur during measurement, they are suppressed by the ballast and have little effect on the operation of the diaphragm. Therefore, the leak amount can be measured with high accuracy without being affected by disturbance such as pressure fluctuation.

According to the leak measuring apparatus of the present invention, when a leak of a predetermined amount or more occurs from the measured object,
The protection means prevents the transmission of the leakage amount to the diaphragm type volume meter. Therefore, it is possible to prevent the diaphragm from being broken due to the transmission of the leakage amount equal to or more than the predetermined amount.

According to the leak measuring device of the present invention, the displacement corresponding to the amount of leakage from the object to be measured is transmitted by the protective film of the displacement restricting mechanism, and the diaphragm changes in volume. When the leakage amount is equal to or more than a predetermined amount, the displacement of the protective film is regulated, so that the diaphragm is prevented from being broken by causing a volume change of more than a predetermined amount.

According to the leak measuring device of the present invention, when the leak measuring medium is a liquid, the protection means is arranged above the mounting position of the measured object. Therefore, the leak amount of the leak measurement medium can be reliably transmitted to the diaphragm type volume meter, and the protection means can be reliably functioned.

According to the leak measuring apparatus of the present invention, since the closed vessel having a sufficiently large volume in comparison with the change in the volume of the diaphragm is connected to the leak measuring system to form a ballast, fluctuations in the atmospheric pressure are obtained. And disturbances such as convection in the atmosphere
Since it hardly affects the volume change of the diaphragm,
High measurement accuracy can be maintained.

According to the leak measuring apparatus of the present invention, the monitoring means can monitor the mounting abnormality of the measured object and the operation abnormality of the protection means. Therefore, the amount of leakage can be measured with high accuracy, and the occurrence of troubles can be prevented and the measurement can be performed safely.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic block diagram of a leak measuring device for implementing the method of the present invention. In the figure, 1 is a diaphragm type volume meter, 2
Is a displacement restricting mechanism for protecting the diaphragm type volume meter 1 from overload; 3 is a measuring table on which the object 4 is airtightly mounted;
Is a ballast connected to the diaphragm type volume meter 1. The airtight leak measuring system 7 is configured by connecting the measuring table 3, the displacement regulating mechanism 2, the diaphragm type volume meter 1, and the stabilizer 5 in this order by the fluid flow paths 6a to 6c. Reference numeral 8 denotes a pressurizing device that pressurizes and supplies a leak measurement medium to the DUT 4 mounted on the measuring table 3.

A diaphragm type volume meter 1 and a displacement restricting mechanism 2
The fluid flow path 6a connecting the fluid flow path 6a and the air side
An opening / closing valve 9 that opens and closes a passage that communicates with the valve is interposed.
The measuring table 3 and the ballast 5 are also connected to the measuring table 3 and
Opening / closing valves 10 and 11 for opening and closing a passage for communicating the fixed device 5 and the atmosphere are arranged. Further, a pressure sensor 12 for measuring the internal pressure of the leak measurement system 7 is disposed on the measurement table 3. Signals from the diaphragm type volume meter 1 and the pressure sensor 12 are input to the arithmetic processing unit 13, respectively. The arithmetic processing unit 13 includes a central processing unit, RAM, RO
M, etc., an input / output interface, etc. (none of which are shown). A predetermined processing program is executed to calculate the amount of leakage, or based on the internal pressure of the leak measurement system 7 measured by the pressure sensor 12. Thus, an abnormal mounting of the object 4 to the measuring table 3 and an abnormal operation of the displacement regulating mechanism 2 are monitored and interlocked.

In the diaphragm type volume meter 1, a diaphragm 22 is hermetically stretched at the center of left and right bodies 21a and 21b divided into two parts. The diaphragm 22 is sensitive to a minute change in volume transmitted through the fluid flow paths 23a and 23b. For example, material SUS4
10. A diaphragm having a thickness of 0.05 mm is preferred. In the bodies 21a and 21b, concave portions (second and first diaphragm chambers) for allowing the displacement of the diaphragm 22 are provided.
a and 24b are formed and communicate with the fluid flow paths 23a and 23b, respectively. As shown in FIG. 2, the diaphragm 2 due to a change in volume of the measurement medium leaking from the DUT 4
The small displacement amount of 2 is measured by a displacement sensor 25 that detects a change in reactance generally used for a pressure sensor or the like, and is output to the arithmetic processing unit 13.

The relationship between the diaphragm displacement amount h (mm) and the volume change V (mm ³ ) is obtained by setting the radius of the diaphragm 22 to r.
(Mm), it is expressed by the following equation.

V = πh (3r ² + h ² ) / 6 Here, by setting the radius r of the diaphragm 22 to an appropriate value, the relationship between the diaphragm displacement h and the volume change V is as shown in FIG. Is a linear proportional relationship. Therefore, there is no need to perform a complicated correction to obtain the volume change V, and the measurement of the leak amount can be performed with a simple configuration.

The displacement restricting mechanism 2 is for protecting the diaphragm 22 by preventing an overload from being applied to the diaphragm type volume meter 1 in case of an excessive leakage of the measured object 4 or the like. A protective film 27 is hermetically stretched at the center between the upper and lower bodies 26a and 26b, and the upper body 26a
, A hemispherical concave portion 28 is formed. The protective film 27 is displaced in accordance with the amount of leakage at the time of normal leak measurement. However, in the case of excessive leakage, the protective film 27 is tightly attached to the concave portion 28 and is regulated so as not to be further displaced. Accordingly, the volume change of the diaphragm 22 is set within an allowable range, and
2 can be protected from being destroyed. And body 2
Fluid flow paths 29a and 29b are formed in 6a and 26b,
The fluid passage 6a and the fluid passage 6b communicate with each other. In this case, the protective film 27 is made of, for example, a material SUS304 and has a thickness of 0.1 mm.
It is preferable to use a metal thin film of 005 mm. When the leak measurement medium is a liquid, the displacement restricting mechanism 2 is connected to the object 4 to be measured.
And horizontally above the mounting position. Thereby, the protective film 27 is in a horizontal posture parallel to the body 26b, and the original position is always secured.

The measuring table 3 is formed with a fluid channel 31a communicating with the fluid channel 6b and two fluid channels 31b and 31c communicating with the fluid channel 31a. Fluid flow path 31a
, The pressure sensor 12 is arranged, measures the internal pressure of the leak measurement system 7, and outputs it to the arithmetic processing unit 13. The fluid flow path 31b includes the object 4 to be measured that is hermetically mounted on the measuring table 3.
Valve 1 that communicates with the air and communicates with the atmosphere
0 is arranged. The ballast 5 is for preventing the diaphragm 22 of the diaphragm type volume meter 1 from being affected by disturbance due to fluctuations in the atmospheric pressure, convection of the atmosphere, and the like. The ballast 5 is an airtight container having a predetermined volume that does not deform due to a change in pressure, and is airtightly connected to the fluid flow path 23a of the diaphragm type volume meter 1 by the fluid flow path 6c. In this case, compared to the change in the volume of the diaphragm 22, the ballast 5
By making the volume of the container sufficiently large, the pressure change in the container of the ballast 5 that changes due to the volume change of the diaphragm 22 can be ignored.

The on-off valves 9 and 11 disposed in the fluid flow path 6a and the ballast 5, respectively, cause the diaphragm 22 of the diaphragm type volume meter 1 to move due to the thermal expansion of the leak measuring medium sealed in the leak measuring system 7. Predetermined value for either one
When it is displaced as described above , it is opened to communicate with the atmosphere and return the diaphragm 22 to its original position.

The operation of the leak measuring apparatus having the above-described configuration will be described in the form of measuring the leak of the object to be measured (fuel injection valve) 4.
The leak measuring medium is supplied to the object under test 4 airtightly mounted on the measuring table 3 by the pressurizing device 8 at a predetermined pressure. If a small leak occurs in the DUT 4, the leak is transmitted to the protective film 27 through the fluid flow paths 31b and 6b,
Further, the light is transmitted to the diaphragm 22 via the protective film 27. The volume of the diaphragm 22 changes according to the transmitted leakage amount. This volume change is measured as a displacement by the displacement sensor 25 and output to the arithmetic processing unit 13.
The arithmetic processing unit 13 calculates the leakage amount from the relationship between the diaphragm displacement amount h (mm) and the volume change V (mm ³ ) shown in FIG.

As described above, the leak measuring method and the leak measuring apparatus of the present invention capture a minute leak from the DUT 4 not as a pressure but as a change in the volume of the leak measuring medium in the airtight leak measuring system 7. The amount of displacement can be measured directly by measuring the amount of displacement by the extremely soft diaphragm 22 that is sensitive to minute volume changes. In addition, by using the above-mentioned soft diaphragm 22, the displacement can be miniaturized to such an extent that the pressure change occurring within the measurement time can be ignored, and the measured value is not affected by the pressure change, and the leak measurement can be performed with high accuracy. Can be.

Further, the diaphragm 22 is provided with a displacement restricting mechanism 2 for protecting the diaphragm 22 from being displaced more than a predetermined amount. Abnormal operation can be monitored to prevent a failure.

(Other Embodiment) FIG. 4 is a schematic block diagram of a leak measuring apparatus showing another embodiment. This leak measuring device measures the amount of leakage of the DUT 44 from which the location of the leak cannot be specified. The DUT 44 is mounted in a closed container 45, and the leak measurement medium is pressurized by the pressurizing device 8. When supplied, a volume change occurs in the closed container 45 according to the leakage amount. This volume change is similar to that of the above-described embodiment.
b → displacement regulating mechanism 2 → fluid flow path 6a → transmitted to diaphragm volume meter 1 and measured by the diaphragm volume meter to calculate the amount of leakage based on the amount of displacement.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a leak measuring device embodying the present invention.

FIG. 2 is an explanatory diagram showing a basic principle of leak measurement.

FIG. 3 is a characteristic diagram showing a relationship between a displacement of a diaphragm and a change in volume.

FIG. 4 is a schematic block diagram showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diaphragm type volume meter 2 Displacement regulation mechanism (protection means) 3 Measuring table 4,44 DUT 5 Ballast 7 Leakage measurement system 8 Pressurizing device (pressurizing means) 12 Pressure sensor (monitoring means) 13 Operation processing unit ( Computing means, monitoring means) 22 diaphragm 27 protective film 28 recess

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 3/12 G01M 3/26

Claims (8)

(57) [Claims] 1. A volume change according to a leak amount from an object to be measured.
When the first diaphragm chamber is formed by a diaphragm
In both cases, the leak measurement medium is sealed in the first diaphragm chamber.
The displacement of the first diaphragm chamber is output as a diaphragm displacement amount, the amount of leakage is calculated by a calculating means , and the first diaphragm is sandwiched by the diaphragm.
The second diaphragm chamber formed on the side opposite to the
The leak measurement medium is contained, and the first diaphragm chamber side and
And the two diaphragm chambers, respectively.
An on-off valve that connects the flam chamber to the atmosphere
Due to the thermal expansion of the leak measurement medium, the diaphragm
A leak measuring method, characterized in that the on- off valve is opened when one of them is displaced by a predetermined value or more . Wherein when the leakage amount is a predetermined amount or more, has a displacement restriction mechanism for protecting the diaphragm and prevents the transmission leakage amount to the diaphragm, provided in the first diaphragm chamber side The on-off valve,
Provided between the diaphragm and the displacement mechanism.
Leakage measuring method according to claim 1, wherein the that. 3. A measuring table for mounting an object to be measured, a pressurizing means for pressurizing a fluid forming a leak measuring medium to supply the fluid to the object to be measured, and a diaphragm according to an amount of leakage from the object to be measured. A leakage measuring system is configured by a diaphragm type volume meter that outputs a volume change as a diaphragm displacement amount, and a ballast that suppresses the influence of disturbance on the diaphragm type volume meter, and calculates the leakage amount from the diaphragm displacement amount. A leak measuring device comprising a calculating means. 4. A leak measuring device according to claim 3, further comprising protection means for preventing transmission of the leak amount to said diaphragm type volume meter when the leak amount from said object to be measured is equal to or more than a predetermined amount. apparatus. 5. The device according to claim 1, wherein the protection unit includes a protection film that is displaced in accordance with an amount of leakage from the object to be measured, and is a displacement restricting mechanism that restricts displacement of the protection film by a predetermined amount or more. The leak measuring device according to claim 4, wherein 6. The leak measuring apparatus according to claim 4, wherein the protection unit is disposed above a mounting position of the measured object when the leak measuring medium is a liquid. . 7. The leak measuring device according to claim 3, wherein the ballast is a closed container having a volume that is sufficiently large as compared with a change in volume of the diaphragm. 8. The apparatus according to claim 3, further comprising a monitoring unit that measures an internal pressure of the leak measuring system and monitors an abnormal mounting of the measured object and an abnormal operation of the protection unit. A leak measuring device according to any one of the claims.