JP2000205991A - Leak tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leak tester such that a plurality of workpieces can be measured with one leak tester and measuring time can be reduced. SOLUTION: During measurements using this leak tester 2, all of selector valves 6, 8, 10, 20, 22, 24,... are first opened and a pressurized gas is introduced from a pressurized gas source 4 into workpieces W1, W2, W3,... and a master M. After a measuring pressure has been reached, the selector valve 6 is closed to establish equilibrium of atmospheric pressure within each workpiece W1,... and the master M. Next, all the selector valves except the selector valve 20 are closed to measure the workpiece W1. The selector valve 20 is then closed and the selector valve 22 opened to make measurements for the workpiece W2. Data about measurements of differential pressure made by a differential pressure detector 12 are compared with master data stored in a master data calculation and storage means 26 and thereby the amount of pressure leaks from the workpiece W2 is calculated by a workpiece pressure leak calculation means 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting a work and a master through a differential pressure detector, introducing a pressurized gas into the work and the master, and measuring a change in the differential pressure, thereby reducing a difference between the work and the master. The present invention relates to a leak tester for measuring pressure leak.

[0002]

2. Description of the Related Art A leak tester is a device for introducing a pressurized gas into a work and measuring the amount of pressurized gas leaking from the work. As a leak tester, a work and a master are connected via a differential pressure detector, pressurized gas is introduced into the work and the master, and a work is performed based on a change in differential pressure generated between the work and the master. In general, a differential pressure type leak tester for measuring a leakage amount of pressurized gas is used.
As such a differential pressure type leak tester, for example, there is an invention of a differential pressure type leak tester described in JP-A-4-221733.

A measuring method using a differential pressure type leak tester described in this publication will be described with reference to FIG. FIG. 7A is a block diagram illustrating a basic configuration of a differential pressure type leak tester according to the related art, and FIG. 7B is a valve chart illustrating opening and closing of an on-off valve. The differential pressure type leak tester 32 shown in FIG. 7A includes a pressurized gas source 34 and a work W, a master M and a differential pressure detector 42.
And the on-off valve 3 provided in the piping system
6, 38, and 40 are centered.

[0004] The pressurized gas source 34 is connected to an on-off valve 36 by a pipe 44A, and the other end of the on-off valve 36 is connected to a pipe 44B. The pipe 44B is branched into a pipe 44C and a pipe 46A, and the pipe 44C is connected to the on-off valve 38, and the other end of the on-off valve 38 is connected to the pipe 44D. Piping 4
4D is branched into a pipe 44E and a pipe 48A.
4E is connected to the work W, and the pipe 48A is connected to the differential pressure detector 4
2 is connected to one side of the measuring unit. On the other hand, pipe 46A
Is connected to the on-off valve 40, and the other end of the on-off valve 40 is connected to a pipe 46.
B. The pipe 46B is the pipe 46C and the pipe 4
8B, the pipe 46C is connected to the master M, and the pipe 48B is connected to the other side of the measuring section of the differential pressure detector 42.

[0005] The differential pressure type leak tester 3 having such a configuration.
2, the work W and the master M into which the pressurized gas is introduced.
Is measured by the differential pressure detector 42 to measure the pressure leak of the work W. That is, FIG.
As shown in (1), first, the on-off valves 36, 38, and 40 are all opened, and pressurized gas is introduced from the pressurized gas source 34 into the work W and the master M. Subsequently, only the on-off valve 36 is closed for a certain period of time, and the pressure in the work W and the pressure in the master M are balanced. Then, the on-off valve 38,
40 is closed, and the differential pressure between the atmospheric pressure in the work W and the atmospheric pressure in the master M is measured by the differential pressure detector 42. Since the air pressure in the work W and the air pressure in the master M have once reached equilibrium by the equilibrium operation, if there is no gas leakage from the work W, the differential pressure detected by the differential pressure detector 42 becomes zero. Become. On the other hand, if there is a gas leak from the work W, the differential pressure detector 42 detects a differential pressure corresponding to the gas leak.

Here, if a plurality of works W are to be tested at the same time, the number of differential pressure type leak testers 32 must be configured, so that the cost becomes extremely high. Therefore, in order to measure a plurality of works with one leak tester, a differential pressure type leak tester 52 having a configuration as shown in FIG. 8 has been developed. The differential pressure type leak tester 52 includes a pressurized gas source 4 and a plurality of workpieces W1, W2, W3,.
, And on-off valves 6, 8, 10, 20, 22, 24,... Provided in the piping system.

The pressurized gas source 4 is connected to the on-off valve 6 by a pipe 14A, and the other end of the on-off valve 6 is connected to a pipe 14B. The pipe 14B is branched into a pipe 14C and a pipe 16A. The pipe 14C is connected to the on-off valve 8, and the other end of the on-off valve 8 is connected to the pipe 14D. The pipe 14D branches into a pipe 14E and a pipe 18A, and the pipe 14E branches into pipes 14F, 14H, and 14K. The pipe 14F is connected to the on-off valve 20, and the other end of the on-off valve 20 is connected to the pipe 14G.
, And the pipe 14G is connected to the first work W1. The pipe 14H is connected to the on-off valve 22, and the on-off valve 2
The other end of 2 is connected to a pipe 14J, and the pipe 14J is connected to a second work W2.

The pipe 14K branches into a pipe L and a pipe N. The pipe L is connected to an on-off valve 24, and the other end of the on-off valve 24 is connected to a pipe 14M. The pipe 14M is connected to the third work W3, and the same structure is continued by the number of works below. The pipe 18A is connected to the differential pressure detector 12
Is connected to one side of the measuring unit. On the other hand, the pipe 16A is connected to the on-off valve 10, and the other end of the on-off valve 10 is connected to the pipe 16B.
It is connected to the. The pipe 16B is the pipe 16C and the pipe 18
B, the pipe 16C is connected to the master M,
The pipe 18B is connected to the other side of the measuring section of the differential pressure detector 12.

A pressure leak test of a plurality of works by the leak tester 52 having such a structure is performed according to a valve chart of FIG. First, as shown in FIG.
The on-off valves 6, 8, 10, and 20 are opened, and all other on-off valves are closed. Thereby, the first work W1
And a pressurized gas is introduced into the master M. Subsequently, the first work W is closed by closing the on-off valve 6 for a certain period of time.
1 and the master M are balanced. Then, the on-off valves 8, 10 are closed, and the differential pressure is measured by the differential pressure detector 12, whereby the pressure leak of the first work W1 is measured.

Next, while the on-off valve 20 is closed,
The on-off valves 6, 8, 10, 22 are opened. by this,
This time, pressurized gas is introduced into the second work W2 and the master M. Subsequently, the air pressure in the second work W2 and the air pressure in the master M are balanced by closing the on-off valve 6 for a predetermined time. Then, the on-off valves 8 and 10 are closed and the differential pressure is measured by the differential pressure detector 12, whereby the second workpiece W
A pressure leak of 2 is measured. Hereinafter, the same procedure is repeated for all the works.

[0011]

By repeating the pressurization, equilibrium, and detection cycle for each of the works W1, W2, W3,..., The pressure leak of a plurality of works is measured by one leak tester 52. Is done. However, in such a measuring method, the cycle of pressurization / equilibration / detection has to be performed for each work, so that there has been a problem that the measurement time becomes extremely long.

It is an object of the invention according to claim 1 of the present application to provide a leak tester capable of measuring a plurality of works with one leak tester and shortening the measurement time.

[0013]

Therefore, in order to solve the above-mentioned problems, the invention described in claim 1 of the claims has been created.

In the leak tester according to the present invention,
The master data, which is a change with time in the pressure in the work when there is no pressure leak from the work, is calculated and stored in advance for each of the plurality of works by the master data calculation storage means. Then, at the time of measurement, first, all on-off valves are opened, and pressurized gas is introduced into a plurality of works and the master. Next, only the first on-off valve is closed, and the air pressure in the plurality of works and the air pressure in the master are balanced. Subsequently, while only one of the work on-off valves is kept open, all other work on-off valves are closed. Then, by measuring the differential pressure with the differential pressure detector, the differential pressure between the work and the master with the open / close valve for the work kept open is measured, and the amount of pressure leakage from the work is measured.

Next, the work on-off valve is closed,
One of the other on-off valves for the workpiece is opened. Then, by measuring the differential pressure with the differential pressure detector, the differential pressure between the work with the work on-off valve opened and the master is measured, and the pressure leak amount from the work is measured. Here, since the equilibrium operation is not performed before the current measurement, a measurement error occurs due to a difference in detection timing. That is,
Although there is actually no pressure leak, there is a pressure leak, but a change in the differential pressure occurs. In order to eliminate this measurement error, the master data for the work is called from the master data calculation and storage means, and the measurement data obtained by the differential pressure detector is compared with the master data. Is calculated.

Hereinafter, the same operation is repeated for other workpieces, and the pressure leakage amount for all the workpieces is calculated. When measurement for all workpieces is completed,
The next measurement is performed by replacing each work with a work of the same type that has not been measured. At this time, the operation of pressurizing and equilibrating only needs to be performed once, and thereafter, the amount of pressure leakage of each work is measured in order. In this way, every time the measurement of all the works is completed, the measurement can be continued by exchanging the next work of the same type.

As described above, in the present invention, the master data for each work is calculated and stored in advance,
By using this master data, it is possible to calculate the pressure leakage amount of all the works by performing the pressurization / equilibration operation only once, and this can be repeated as many times as the work is replaced. Therefore, as the number of times of replacement of the workpiece is larger, the measurement time is further shortened as compared with the conventional technique shown in FIG. Thus, according to the leak tester of the present invention, a plurality of works can be measured with one leak tester, and the measurement time can be reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. First, the overall configuration of the leak tester according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the overall configuration of the leak tester of the present embodiment. As shown in FIG. 1, the piping configuration of the leak tester 2 of the present embodiment is the same as that of the leak tester 52 shown in FIG.
The same reference numerals are given and the description is omitted. The leak tester 2 of the present embodiment differs from the conventional leak tester 52 in that the leak tester 2 includes a master data calculation storage unit 26 and a work pressure leak amount calculation unit 28.

The master data calculation storage means 26 and the work pressure leak amount calculation means 28 are a CPU (central processing unit).
And a computer system mainly configured with RAM and ROM memory devices. The master data calculation storage means 26 is electrically connected to the differential pressure detector 12, and each work W1, W2, W
The master data of each of the workpieces W1, W2, W3,... Is calculated and stored according to the procedure described below. Work pressure leak amount calculation means 2
Reference numeral 8 denotes each work W1, W2,
The amount of pressure leakage from each of the works W1, W2, W3,... Is calculated by comparing the measurement data for W3,.

The on-off valves 6, 8, 10, 20, 22,
Reference numerals 24,... All denote electromagnetic switching valves, which are controlled to open and close by control signals from a control unit (not shown). Further, the on-off valve 6 corresponds to a first on-off valve in the present invention. The on-off valve 8 corresponds to a second on-off valve in the present invention, and the on-off valve 10 corresponds to a third on-off valve in the present invention. Further, the on-off valves 20, 22, 24,... Correspond to the work on-off valves in the present invention.

Now, a plurality of works W1, W2, W3, using the leak tester 2 of this embodiment having such a configuration.
Are described with reference to FIG. FIG. 2 is a valve chart showing the opening and closing of each on-off valve at the time of measurement using the leak tester 2 of the present embodiment.
As shown in FIG. 2, first, all the on-off valves 6, 8, 1
Are opened, and pressurized gas is introduced from the pressurized gas source 4 into the respective works W1, W2, W3,. When the pressure in each of the works W1, W2, W3,...
Are closed, and the pressure in each of the works W1, W2, W3,... And the master M is balanced.

When the balancing operation is completed, all the on-off valves except the on-off valve 20 are closed, and the measurement of the first work W1 is performed (detection 1). Since the detection 1 is a measurement immediately after the equilibrium operation is performed, there is no need to calculate master data, and the pressure leak amount is directly measured from the differential pressure data from the differential pressure detector 12. When the detection 1 is completed, the on-off valve 20 is subsequently closed and the on-off valve 22 is opened. After a delay time of about 0.5 to 1 second, the measurement of the second work W2 is performed (detection 2). The delay time is provided by the on-off valve 2.
This is to prevent a measurement error due to a change in air pressure accompanying the opening and closing of 0,22.

Here, since the balancing operation is not performed before the measurement of the detection 2, a measurement error occurs due to the difference in the detection timing. That is, although there is actually no pressure leak, a change in the differential pressure occurs as in the case where there is a pressure leak. In order to eliminate the measurement error, the master data for the second work W2, that is, the time-dependent change of the pressure in the second work W2 when there is no pressure leak from the second work W2, is used as master data calculation storage means. The true pressure leak amount is calculated by calling and comparing them from 26.

Here, when the master data of the second work W2 has already been calculated and stored by the master data calculation storage means 26, that is, when the measurement is performed in the second and subsequent steps, the detection 2 is performed. Is the differential pressure detector 12
By comparing the differential pressure measurement data with the master data, the work pressure leak amount calculating means 28 calculates the pressure leak amount of the second work W2. Then, the opening / closing valve 22 is closed, the opening / closing valve 24 is opened, and after a delay time, the measurement of the third work W3 is performed (detection 3).

On the other hand, when the first measurement is performed and the master data has not been calculated yet, in the detection 2, the master data acquisition operation for the second work W2 is performed. As will be described later, since the pressure leak amount from the work is also calculated in the process of calculating the master data, it takes more time than the second and subsequent measurements, but it is necessary to acquire the master data for the second work W2. At the same time, the amount of pressure leakage from the second work W2 is also measured.

Next, the procedure for calculating the master data will be described with reference to FIGS. First, the principle of master data calculation will be described with reference to FIGS. FIG. 3 is a graph showing a change in differential pressure in pressure leak measurement. The solid line shows the case where there is no pressure leak of the work, and the broken line shows the case where there is pressure leak of the work. As shown in FIG. 3, when the on-off valves 8, 10 are closed at time t0 to shut off the work and the master, a differential pressure is generated accordingly. The generated differential pressure gradually changes with pressure fluctuation.

Here, the internal pressure of the work actually fluctuates due to adiabatic compression or the like in the range from time t0 to time t1, and in this range, the differential pressure ΔP caused by pressure leakage from the work is reduced. , The value to which the differential pressure ΔP0 due to the pressure fluctuation is added is detected as the differential pressure value. After time t1, only the differential pressure ΔP caused by pressure leakage from the work is detected as a differential pressure value.

Here, if the inspection conditions such as the volume of the work, the measured pressure, the temperature of the work and the external temperature are the same, the differential pressure ΔP0 caused by the pressure fluctuation will always be the same value even if the measurement is performed a plurality of times. Should be taken. In other words, the differential pressure curve (solid line) from time t0 to time t1 for a work with no pressure leakage is the same if the inspection conditions are the same. Further, the differential pressure curve (dashed line) from time t0 to time t1 for a work having a pressure leak is obtained by adding the differential pressure ΔP due to the pressure leak to the curve of ΔP0. Then, the amount of change in the pressure difference ΔP due to the pressure leak per unit time should be constant regardless of the presence or absence of the pressure fluctuation.

Accordingly, by subtracting the solid line from the broken line in FIG. 3, the temporal change of the differential pressure ΔP caused by the pressure leak is obtained as shown in FIG.
It changes linearly not only after 1 but also between time t0 and time t1. Therefore, if a differential pressure curve for a workpiece having no pressure leak under a specific inspection condition is previously obtained and a process of subtracting the differential pressure curve from the workpiece under the same inspection condition is performed, the differential pressure Δ as shown in FIG.
The amount of change of P per unit time is obtained, and the magnitude of pressure leak of the work can be calculated from this. By using such a calculation method, the time t0 at which the pressure fluctuates
It is possible to calculate the magnitude of the pressure leak even in the range from to time t1.

This "differential pressure curve for a work having no pressure leak under specific inspection conditions" (solid line in FIG. 3) is master data. In order to obtain the master data, first, the amount of change in the pressure difference ΔP per unit time (the straight line in FIG. 4) is obtained in a range where the pressure does not fluctuate after time t1 for the work, and this is used as the differential pressure curve for the work (FIG. 3). (Dashed line). This time t1 is a point at which the amount of change in the differential pressure per unit time becomes constant regardless of the presence or absence of pressure leakage from the work, that is, the second derivative of the curve drawn by the measured value of the differential pressure by the differential pressure sensor. Can be obtained as a point where becomes zero. In the present embodiment, the point at which the amount of change in the differential pressure per unit time becomes constant uses the moving average value of the differential pressure sensor instead of the measured value itself. 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 measured value X at every preset sampling time. The moving average calculation number N of the measured value X
A moving average value P is calculated for each P, and the calculated moving average value P is taken in as a detection value XP. This detection value XP
Is used, the one-time differential value D1 is calculated by the following equation (1) for each preset change amount calculation unit time C1. 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 value D2AVE is calculated from the second derivative D2 by the weighted moving average method, and a point at which the weighted average value D2AVE becomes zero is defined as time t1. When it is determined that the time t1 has been reached in this way, the amount of change per hour (the slope of the straight line in FIG. 4) of the measured value of the differential pressure ΔP is determined from that point in time. Then, by subtracting this from the differential pressure curve for the workpiece (dashed line in FIG. 3), master data (solid line in FIG. 3) is obtained.
This master data is stored together with the inspection conditions at that time.

Now, using the master data stored in this way, the amount of pressure leak from the work is calculated. First, a differential pressure curve of the work is measured, and it is determined whether or not the inspection conditions at this time can be regarded as the same as the inspection conditions at the time of obtaining the master data. If the inspection conditions cannot be regarded as the same, new master data is obtained for the new inspection conditions by the above-described procedure.

If the inspection conditions can be considered to be the same, a process of subtracting the master data from the differential pressure curve of the work is performed, and the amount of change in the differential pressure ΔP per unit time is obtained as shown in FIG. Then, the pressure leakage amount VL of the work is calculated using the amount of change per hour of the differential pressure ΔP. Various methods can be used as a specific method of this calculation. For example, a method for obtaining from the differential pressure measurement value X or the detection value XP between the time t1 and another point, a method using a moving average per unit time, and a change in the amount of change per unit time (for example, the first derivative D1) This is a method based on averaging.

Next, more specific contents of the procedure for acquiring master data in the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a procedure for obtaining master data. The following procedure is executed on the master data calculation storage unit 26. Step S in FIG.
When the measurement is started at 10, parameters for the workpiece and the master are input (step S12).
The parameters include the size and shape of the work 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 the moving average P can be calculated (step S16). This determination does not become YES until the measured value X is inputted by the number NP necessary for calculating the moving average, and the process returns to step S14 to return to the measured value X.
Is repeated. When the number of measurement values X required for the calculation of the moving average has been input, the process proceeds to step S18, where the moving average P is calculated. The value of the moving average P thus calculated is input as the detection value XP (step S20).

Next, it is determined whether or not the change amount can 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 according to 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 for the number necessary for calculating the moving weighted average, the process proceeds to step S28, where the weighted average D2AVE is calculated.

It is determined whether or not the pressure has stabilized based on whether or not the weighted average value D2AVE thus calculated is zero (step S30). If the weighted average value D2AVE is zero, the determination is YES, the determination in step S32 is also YES, and the leak differential pressure ΔP is calculated (step S34). Then, by subtracting the data of the leak differential pressure ΔP from the differential pressure curve of the work, master data ΔPM is obtained and stored together with the inspection conditions (step S36). Thus, the master data calculation procedure ends (step S38).

Next, a procedure for obtaining the pressure leak amount using the master data calculated in this manner will be described with reference to FIG. FIG. 6 is a flowchart showing a procedure for obtaining the pressure leak amount using the master data. The following procedure is executed on the master data calculation storage unit 26 and the work pressure leak amount calculation unit 28. When the measurement is started in step S40 in FIG. 6, first, parameters for the workpiece and the master are input (step S4).
2). Parameters include the size and shape of the work
There are the size and shape of the master. Next, it is determined whether or not the inspection conditions when measuring the differential pressure curve for the workpiece this time can be regarded as the same as the inspection conditions when the master data is obtained (step S44). If the inspection conditions cannot be regarded as the same, new master data is obtained for the new inspection condition by the procedure shown in FIG. 5 (step S46).

On the other hand, if the inspection conditions can be regarded as the same, the measured value X of the differential pressure by the differential pressure sensor is input (step S48). Subsequently, it is determined whether the moving average P can be calculated (step S50). This determination is not YES until the number of measurement values X required for the moving average calculation is input, and the process returns to step S48 to repeat the input of the measurement value X. When the number of measurement values X necessary for the calculation of the moving average have been input, the process proceeds to step S52, where the moving average P is calculated. The value of the moving average P thus calculated is input as the detection value XP (step S54).

As described above, the detected value X thus obtained is
By subtracting the value ΔPM of the master data at the same time from the value of P, the value of the leak differential pressure ΔP is calculated according to the following equation (3) (step S5).
6). ΔP = XP−ΔPM (3) By obtaining two or more values of the leak differential pressure ΔP,
The inclination of the broken line in FIG. 4, that is, the change amount can be obtained. Subsequently, it is determined whether or not the change amount can be calculated (step S58). When the preset change amount calculation unit time C1 has elapsed, this determination is YES, and the one-time differential value D1ΔP is calculated using the two values of the leak differential pressure ΔP according to the following equation (4) (step S1). S6
0). D1 (N) ΔP = ΔP (N) −ΔP (N-C1) (4)

Subsequently, it is determined whether or not the leak amount can be calculated (step S62). One-time differential value D1Δ
This determination is not YES until P is calculated by the number required for the moving weighted average calculation, and the process returns to step S48 to repeat the above-described steps. When the first derivative D1ΔP is calculated by the number necessary for calculating the moving weighted average, the process proceeds to step S64, and the leak amount VL is calculated. Thus, the procedure of measuring the pressure leak amount using the master data ends (step S66).

As described above, the leak tester 2 of the present embodiment
In the above, a process of subtracting the master data obtained in advance from the differential pressure curve of the work is performed to obtain a change amount of the differential pressure ΔP per unit time, and the pressure leak amount of the work is calculated using the change amount of the differential pressure ΔP per unit time. VL is calculated. Therefore, even after the detection 2 in FIG. 2, the magnitude of the pressure leak can be calculated without repeating the pressurization / equilibration operation. And all the works W1, W2, W
When the measurement of the workpieces 3, 3, ... is completed, the workpieces W1, W2, W3, ... are replaced with new ones of the same kind.
.. Can be measured. Thus, in the leak tester 2 of the present embodiment, a plurality of works can be measured by one leak tester, and the measurement time can be reduced.

In the present embodiment, each of the on-off valves 6, 8,
Although an example using an electromagnetic valve as 10, 20, 22, 24,... Has been described, other automatic opening / closing valves such as an electric valve and a hydraulic valve, and a manual opening / closing valve can also be used. The structure, shape, size, material, connection relationship, and the like of other parts of the leak tester are not limited to the present embodiment.

Further, as an effect unique to this embodiment,
Since the solenoid valves are used for the respective on-off valves 6, 8, 10, 20, 22, 24,..., Automatic control by the control unit becomes possible, and more precise measurement can be performed.

[0046]

According to the first aspect of the present invention, a plurality of works can be measured by one leak tester, and the measuring time can be shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a leak tester according to the present invention.

FIG. 2 is a valve chart showing opening and closing of each on-off valve at the time of measurement using one embodiment of a leak tester.

FIG. 3 is a diagram showing a change in differential pressure in pressure leak measurement according to an embodiment of a leak tester.

FIG. 4 is a diagram showing a temporal change of a differential pressure ΔP caused by pressure leak in pressure leak measurement according to an embodiment of a leak tester.

FIG. 5 is a flowchart showing a procedure for obtaining master data in one embodiment of the leak tester.

FIG. 6 is a flowchart illustrating a procedure for obtaining a pressure leak amount using master data according to an embodiment of the leak tester.

FIG. 7 is a block diagram showing an overall configuration of a leak tester according to the related art and a valve chart showing opening and closing of an on-off valve.

FIG. 8 is a block diagram showing an overall configuration of another leak tester according to the related art.

FIG. 9 is a valve chart showing opening and closing of an on-off valve of another leak tester in the related art.

[Explanation of symbols]

 2 Leak tester 4 Pressurized gas source 6 First on-off valve 8 Second on-off valve 10 Third on-off valve 12 Differential pressure detector 20, 22, 24,... Work on-off valve 26 Master data calculation storage means 28 Work pressure Leakage amount calculation means M master W1, W2, W3,.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Yamakawa 50, Higashisumiyoshi, Tsutsumi-cho, Toyota-shi, Aichi F-term (Reference) 2G067 BB28 DD03 EE09

Claims (1)

[Claims] 1. A leak tester for measuring a pressure leak amount of each of a plurality of works by introducing a pressurized gas into a plurality of works and a master, wherein the pressurized gas is introduced into the plurality of works and the master. A pressurized gas source for connecting the pressurized gas source to the plurality of workpieces and the master; and a pressurized gas source, the plurality of workpieces and the master provided in the pipe system. A first on-off valve for simultaneously opening and closing between the first and second on-off valves, a second on-off valve for opening and closing between the first on-off valve and the plurality of works, provided on the piping system, and provided on the piping system. A third on-off valve for opening and closing between the first on-off valve and the master, and a work on-off valve provided in the piping system on a front side of each of the plurality of works; On-off valve and on-off valve for the workpiece And a differential pressure detector provided in the piping system between a pipe connecting the third on-off valve and the master, and a differential pressure detector electrically connected to the differential pressure detector, A master data calculation storage unit that obtains a time-dependent change in pressure in the plurality of works for each of the plurality of works when there is no pressure leak from the plurality of works and stores the master data as master data; A work pressure electrically connected to a differential pressure detector and calculating a pressure leak amount from each of the plurality of works by comparing measurement data of each of the plurality of works by the differential pressure detector with the master data. A leak amount calculator.