JP2001059793A - Air leak test method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air leak test method capable of performing highly accurate tests in a short time. SOLUTION: In normal test mode, an initial pressure from a pressure supply means 10 is supplied for a master-side branch passage 21 and work-side branch passage 22 via a common passage 20. Then after a test pressure is supplied, opening/closing valves 27 and 28 are closed and waited for a predetermined waiting time, a leak from a work W connected to the work-side branch passage 22 is detected from a differential pressure detected at a differential pressure sensor 29. Furthermore, in special test mode to be executed as necessary or periodically, after the opening/closing valves 27 and 28 are closed and waited for a longer waiting time than in the normal test mode, a differential pressure component which linearly changes due to leak is subtracted from the detected differential pressure to obtain a differential pressure component which does not change. The time from the start of the initial pressure supply to the switching to the test pressure, a pressure difference between the initial pressure and test pressure, etc., are adjusted so as to reduce the differential pressure component which does not change to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an air leak test method and apparatus.

[0002]

2. Description of the Related Art A general differential pressure type air leak tester called a balanced type will be briefly described. A master side and a work side branch path are connected to a common path extending from a test pressure source. A master container is connected to the master side branch passage,
The work is connected to the work-side branch passage. The master container has the same shape, volume, and material as the work, and has been confirmed to have no leakage. In the above device,
After the test pressure is applied to the two branch passages from the test pressure source, these branch passages are cut off to form a closed system independent of each other. Thereafter, the differential pressure between the two closed branch passages is monitored to detect a work leak.

When a test pressure is applied, the temperature of the air in the work and the master container once rises due to the heat generated by the adiabatic compression, and then calms down to the ambient temperature due to heat radiation. Even after the branch passage is closed, the above-described heat radiation continues, and the pressure of the two branch passages in the closed state decreases. However, the pressure decrease of the two branch passages due to this heat radiation is due to the same heat radiation characteristics of the master container and the work. Equal to each other. Therefore, the differential pressure is not affected by the pressure drop due to the heat radiation, and the pressure drop corresponding to the work leakage can be reliably detected.

However, if the master container is made to have the same shape, material, and volume as the workpiece as described above, a large number of types of small-quantity production lines require many types of master containers, which increases equipment costs and management costs. Had become. Therefore,
Recently, a non-equilibrium type device has been developed in which a master container having a predetermined shape, volume, and material is used without changing the master container even if the work is different. In this device as well, the test pressure is applied to the two branch passages, and after a predetermined waiting time has elapsed, the branch passages are closed and the differential pressure is detected, as in the above-mentioned balanced type device. The master container has a heat radiation characteristic different from that of the work. Therefore, even if there is no leak in the work, a pressure difference is generated due to the difference in the heat radiation characteristic. This is because the branch passage is closed after the heat radiation is almost eliminated, and only the differential pressure caused by the leakage is detected. As a result, there is a disadvantage that the test time becomes longer.

Therefore, in the leak test apparatus disclosed in Japanese Patent Publication No. 19440/1992, an initial pressure higher than the test pressure is applied first, and then the test pressure is applied. When an initial pressure higher than the test pressure is applied, the heat generated by the adiabatic compression is greater than when the test pressure is applied, and the air temperature in the workpiece becomes higher than when the test pressure is applied.
Therefore, the amount of heat radiation also increases. Then, when the pressure is reduced to the test pressure, heat is taken away with the adiabatic expansion, so that the air temperature in the work is forcibly reduced to the ambient temperature. Therefore, the branch passage can be closed without waiting for a long time for heat radiation, and leak detection based on the differential pressure can be performed, so that the test time can be shortened.

[0006]

In the apparatus disclosed in the above publication,
By dissipating heat after applying the initial pressure, and removing heat by adiabatic expansion in the process of changing from the initial pressure to the test pressure,
The air temperature in the work is forcibly set to the ambient temperature, and thereafter, the influence of the heat radiation characteristics of the work is eliminated. Therefore, the time from the initial pressure application start to the test pressure and the difference between the initial pressure and the test pressure are optimally set. However, since these settings are fixed, if the ambient temperature changes, the air temperature in the work will not be equal to the ambient temperature after the test pressure is switched, and the effect of heat radiation will remain even after the branch passage is closed. There were times when we couldn't do it correctly.

[0007] The above discussion can also be applied to a simple type air leak test apparatus which is not a differential pressure type. In this apparatus, a test pressure source is connected to an upstream end of a passage, and a work is connected to a downstream end. After the test pressure is applied, the passage is closed, and leakage of the work is detected based on a change in pressure of the closed passage. Even with this device, in order to eliminate the effects of pressure fluctuations due to heat radiation, close the passage after the test pressure is applied and wait until the heat radiation calms down, or wait for the pressure to change linearly after the passage is closed, and then check for pressure-based leakage. The test time was long because it was detected. Also, if the method of forcibly adjusting the air temperature in the work to the ambient temperature by lowering to the test pressure after applying the initial pressure is adopted, the leak detection cannot be performed accurately due to the fluctuation of the ambient temperature as described above. was there.

[0008]

According to a first aspect of the present invention, there is provided:
In the differential pressure type air leak test method, in a normal test mode, an initial pressure is supplied from a pressure supply unit to a master-side and work-side branch passage through a common passage, and then a test pressure is supplied. After being closed, the branch passages on the master side and the work side are closed independently, and after waiting for a predetermined waiting time in this closed state, the work connected to the work side branch passage is detected based on the differential pressure detected by the differential pressure sensor. Detect leaks and run a special test mode as needed or periodically, this special test mode
After performing the initial pressure supply and the test pressure supply under the same conditions as in the normal test mode and closing the on-off valve, and after waiting for a longer waiting time than in the normal test mode, from the differential pressure detected by the differential pressure sensor, By subtracting the differential pressure component that changes linearly due to the leak, a differential pressure component that does not change is obtained, and the test pressure is started from the start of the initial pressure supply in the normal test mode so that the differential pressure component that does not change becomes zero. The method is characterized in that one or both of the pressure difference between the initial pressure and the test pressure is adjusted during the time until the pressure is changed to (i).

According to a second aspect of the present invention, in the differential pressure type air leak test apparatus, the control means controls the pressure supply means in a normal test mode, so that the master side and the work side branch through a common passage. An initial pressure is supplied to the passage, and then a test pressure is supplied. Thereafter, the on-off valve is closed, and the branch passages on the master side and the work side are closed independently. After waiting a predetermined waiting time in this closed state, From the differential pressure detected by the differential pressure sensor, leakage of the work connected to the work-side branch passage is detected, and the control unit also executes a special test mode. After supplying the initial pressure and the test pressure under the same conditions as in the test mode and closing the on-off valve, wait for a longer waiting time than in the normal test mode, and then detect the differential pressure detected by the differential pressure sensor. Et al., By subtracting the difference pressure component varies linearly due to the leakage, to obtain a difference pressure component unchanged,
The time from the start of the initial pressure supply in the normal test mode to the switching to the test pressure and / or one or both of the pressure difference between the initial pressure and the test pressure are adjusted so that the unchanged differential pressure component becomes zero. It is characterized by the following.

A third aspect of the present invention is a simple air leak test method. In a normal test mode, an initial pressure is supplied to a work through a passage by controlling a pressure supply means, and then a test is performed. Supply the pressure, then close the work by closing the on-off valve, wait a predetermined waiting time in this closed state, detect the leakage of the work from the pressure detected by the pressure sensor, and if necessary or periodically Perform a special test mode on this special test mode,
After performing the initial pressure supply and the test pressure supply under the same conditions as in the normal test mode and closing the on-off valve, and after waiting for a longer waiting time than in the normal test mode, the detection pressure of the pressure sensor causes a leak. The time from the start of the initial pressure supply in the normal test mode to the switching to the test pressure so as to obtain the pressure component that does not change by subtracting the pressure component that changes linearly due to the pressure and to make this pressure component that does not change zero. And adjusting one or both of the pressure difference between the initial pressure and the test pressure.

According to a fourth aspect of the present invention, in the simple type air leak test apparatus, the control means supplies the initial pressure to the work through the passage by controlling the pressure supply means in a normal test mode. Next, a test pressure is supplied.After that, the opening / closing valve is closed to close the work, and after waiting for a predetermined waiting time in this closed state, the leakage of the work is detected from the pressure detected by the pressure sensor. ,
Furthermore, a special test mode is also executed. In this special test mode, after the initial pressure supply and the test pressure supply are performed under the same conditions as the normal test mode, the on-off valve is closed,
After waiting for a longer waiting time than in the normal test mode, a pressure component that changes linearly due to leakage is subtracted from the pressure detected by the pressure sensor to obtain a pressure component that does not change. And adjusting one or both of the pressure difference between the initial pressure and the test pressure during the time from the start of the initial pressure supply in the normal test mode to the switching to the test pressure. And

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The differential pressure type air leak test apparatus shown in FIG.
And a common passage 20 having an upstream end connected to the pressure supply means 10, and a master-side branch passage 21 and a work-side branch passage 22 branched from the common passage 20.

The pressure supply means 10 includes a positive pressure air pressure source 11 and a source flow passage 12 connected to the air pressure source 11.
And an initial pressure supply passage 13 branched from the main flow passage 12.
And test pressure supply passages 14, and these passages 13, 14
Relief type regulators 15 respectively provided in
16 and 2 connected to downstream ends of these passages 13 and 14.
And a 3 port position electromagnetic switching valve 17. The regulators 13 and 14 are set to an initial pressure and a test pressure, respectively. The initial pressure is higher than the test pressure (large absolute value). The switching valve 17 is configured to selectively connect the common passage 20 to one of the initial pressure supply passage 13 and the test pressure supply passage 14. In the present embodiment, the common passage 20 is connected to the initial pressure supply passage 13 at the off position, and is connected to the test pressure supply passage 14 at the on position.

In the middle of the common passage 20, a two-position three-way electromagnetic switching valve 23 is provided. This switching valve 23 is
At the off position, the downstream portion of the common passage 20 is shut off from the upstream portion and opened to the atmosphere, and at the on position, the downstream portion is connected to the upstream portion.

The branch passages 21 and 22 are provided with normally open solenoid valves 27 and 28, respectively. further,
Two ports of a differential pressure sensor 29 are connected to the branch passages 21 and 22 on the downstream side of the on-off valves 27 and 28.

A master container M is connected to a downstream end of the master side branch passage 21. The master container M has a predetermined shape, volume, and material, and is different from a work W described later. The master container M is designed so that the heat release after adiabatic compression is completed in a short time by reducing the volume and attaching a radiation fin. Further, the downstream end of the master-side branch passage 21 may be closed by omitting the master container itself.
A work W to be inspected is connected to the downstream end of the work side branch passage 22.

The air leak test apparatus according to the present embodiment further includes control means 30. This control means 30
Based on the time measured by the built-in timer, the switching valves 17 and 2
3. Control the on-off valves 27 and 28 sequentially. Further, the control means receives the detection signal from the differential pressure sensor 29 and displays the display 31, the pass lamp 32, the reject lamp 33
Control.

The operation of the device having the above configuration is controlled by the control means 3.
The description focuses on the action of 0. First, valve control in a normal test mode will be described with reference to FIG. By turning on the switching valve 23 to connect the upstream portion and the downstream portion of the common passage 20, the initial pressure supply circuit 13 is connected to the branch passage 2.
Let them communicate with 1 and 22. As a result, the branch passages 21 and
2 and the initial pressure to the master container M and the work W.
When a predetermined time Ta has elapsed from the start of the initial pressure supply,
The switching valve 17 is turned on to switch the connection of the common passage 20 from the initial pressure supply circuit 13 to the test pressure supply circuit 14. As a result, the test pressure is supplied to the branch passages 21, 22, the work W, and the master container M via the common passage 20. Then, when a predetermined time Tb has elapsed from the switching to the test pressure, the on-off valves 27 and 28 are closed, and the branch passages 21 and 22 are closed.
Into an independent closed system. And, these on-off valves 27, 2
At a point in time when a predetermined time Tc has elapsed from the point in time when the valve 8 was closed, the open / close valves 27 and 28 are opened, the switching valve 23 is turned off, and the master container M and the work W are opened to the atmosphere to end the test.

Next, changes in the pressure of the work W and the air temperature in the work at each of the times Ta, Tb, and Tc will be described in detail with reference to FIGS. First, at a predetermined time Ta from the start of the initial pressure supply, the pressure in the work W reaches the initial pressure over time T1. At this time T1, the work W (exactly, the switching valve 23
Heat is generated by the adiabatic compression in all components downstream of the device. Therefore, the air temperature in the work W rises from the ambient temperature.

The workpiece W is maintained at the initial pressure for the remaining time T2 of the predetermined time Ta after reaching the initial pressure. At this time T2, heat is radiated in the work W that has become higher than the ambient temperature, and the air temperature in the work W decreases toward the ambient temperature while drawing an exponential curve. At this time, the larger the temperature difference, the larger the amount of heat radiation, so that a large temperature drop can be obtained even during the short initial time T2 of heat generation.

When the test pressure is switched after the elapse of the time Ta, the compressed air is released from the regulator 16. Since this means adiabatic expansion, heat is taken downstream from the regulator 16.
Therefore, in the compressed air discharge time T3, the air temperature in the work W rapidly decreases and becomes equal to the ambient temperature. As a result, thereafter, the pressure drop of the work W due to heat radiation does not occur. A short time T4 obtained by subtracting the actual release time T3 from the predetermined time Tb from the test pressure switching time ensures that the test pressure is completely reached, and a slight temperature between the workpiece W and the ambient temperature. It is time to resolve the difference.

At a predetermined time Tc after closing the on-off valves 27 and 28, a detection time T6 is set after the waiting time T5. The waiting time T5 is a time for waiting for the pressure fluctuation generated in the branch passages 21 and 22 to calm down due to the closing operation of the on-off valves 27 and 28.

At the detection time T6, a leak is detected from the differential pressure detected by the differential pressure sensor 29. Specifically, the amount of leakage is obtained from the slope of the differential pressure change at the detection time T6. It is preferable that the leakage amount is an atmospheric pressure-converted leakage amount per unit time calculated from the differential pressure information and the test pressure.

As described above, by utilizing adiabatic expansion, pressure fluctuations caused by heat radiation can be eliminated in a short time, and when the on-off valves 27 and 28 are closed, the air temperature in the work W becomes lower than the ambient temperature. Since the pressure difference is equal and the pressure drop due to heat radiation does not occur, the detected differential pressure includes only the differential pressure component caused by the leakage of the work W. As a result, leak detection can be performed accurately. The leak amount is displayed on the display 31, and if the leak amount is lower than the allowable value, the pass lamp 32 is turned on, and if the leak amount is higher, the reject lamp 33 is turned on.

The operation in the normal test mode described above is as follows.
This is the same as the device disclosed in the above-mentioned publication. In this normal test mode, the difference ΔP between the initial pressure and the test pressure
x and the time Ta from the start of the supply of the initial pressure to the switching to the test pressure are, in an environment where the ambient temperature is a standard temperature of, for example, 25 ° C., the dissipation of the adiabatic compression heat during the supply of the initial pressure and the adiabatic expansion during the switch of the test pressure Due to the accompanying temperature drop, the air temperature in the work W is set to exactly match the ambient temperature. However, in practice, the ambient temperature at the time of the test is different from the standard temperature, and varies depending on the season, time, air conditioning environment, and the like. If the ambient temperature is significantly different from the standard temperature, the air temperature in the workpiece W becomes higher or lower than the ambient temperature at the time of closing the on-off valves 27 and 28, and heat is released to the detected differential pressure at the detection time T6. In addition, a differential pressure component due to heat absorption is included, and accurate leak detection cannot be performed. That is, as shown exaggeratedly in FIG.
The detected differential pressure ΔPd indicated by the solid line includes not only the differential pressure component ΔPm due to leakage indicated by the one-dot chain line, but also the differential pressure component ΔPh caused by heat radiation indicated by the broken line.

Therefore, in this embodiment, if necessary,
Alternatively, a special test mode is executed periodically (for example, every fixed time or every time a normal test mode is performed a predetermined number of times). In this special test mode, the control up to the closing of the on-off valves 27 and 28 is the same as that in the above-described normal test mode, so that the description is omitted.

In the special test mode, the on-off valves 27, 2
The time Tc 'from when the shutter 8 is closed to when it is reopened and opened to the atmosphere is made several times longer than the time Tc in the normal test mode. More specifically, the waiting time T5 ′ from the time when the on-off valves 27 and 28 are closed is changed to the waiting time T in the normal test mode.
5, and the detection time T6 'is set to be substantially the same as the detection time T6 in the normal test mode.

As described above, if the air temperature inside the work W differs from the ambient temperature when the on-off valves 27 and 28 are closed, heat or heat is absorbed in the work W and the pressure of the work W fluctuates. A differential pressure component occurs. Hereinafter, work W
Will be described with reference to FIG. 4 again. In the special test mode, since the waiting time T5 'is long as described above, when the waiting time T5' has elapsed, the heat radiation of the work W has been completed.
The air temperature inside matches the ambient temperature. Therefore, at the detection time T6 ', the differential pressure component ΔPh accompanying the heat radiation does not change and is included in the detected differential pressure ΔPd as a constant value. However, since the differential pressure component ΔPm due to leakage changes linearly, the detected differential pressure ΔPd also changes linearly. The control means 30 can accurately calculate the differential pressure component ΔPm accompanying the leak by moving the linear line of the detected differential pressure ΔPd in parallel until it becomes zero when the on-off valves 27 and 28 are closed, Based on this, an accurate leak amount can be detected as in the normal test mode.

By subtracting the differential pressure component ΔPm caused by leakage from the detected differential pressure ΔPd, the work W
A constant pressure difference component ΔPh resulting from heat radiation of the device can be obtained. From the differential pressure component ΔPh, the on-off valve 2
At the time of closing of steps 7 and 28, the time Ta at which the air temperature in the work W can be made to match the ambient temperature is calculated, and in the next normal test mode, the updated time Ta is calculated.
The switching operation of the switching valve 17 is performed at the timing based on.

The increase or decrease of the time Ta based on the differential pressure component ΔPh is performed by using a previously created map. Differential pressure component Δ
If the value of Ph is positive, it means that the temperature of the air in the work W is higher than the ambient temperature when the on-off valves 27 and 28 are closed.
Increase the amount of heat radiation. If the differential pressure component ΔPh is negative, it means that the air temperature in the work W is lower than the ambient temperature when the on-off valves 27 and 28 are closed.
To reduce heat dissipation at the initial pressure.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment relates to a simple air leak test apparatus, not a differential pressure type. In this device, the upstream end of the passage 20 ′ is connected to the pressure supply means 10, and the downstream end is connected to the work W. In the passage 20 ′, a switching valve 23 and an on-off valve 27
A pressure sensor 29 ′ is provided downstream of the on-off valve 27.
Is connected.

In the above apparatus, the sequence control of the switching valves 17, 23 and the opening / closing valve 27 by control means (not shown) is the same as in the first embodiment, and a special test mode is executed in addition to the normal test mode. This is exactly the same as the first embodiment. The difference is that the pressure sensor 29 '
The only difference is that the pressure of the work W is detected instead of the differential pressure. Therefore, the description of the operation of the second embodiment is omitted by replacing the differential pressure with the pressure in the description of the operation of the first embodiment.

In the first and second embodiments, in the special test mode, the differential pressure component ΔP caused by heat radiation and heat absorption.
Although the time Ta is adjusted so that h (pressure component) becomes zero, the pressure difference ΔPx between the initial pressure and the test pressure may be adjusted instead of the time Ta. That is, the differential pressure component ΔPh
Is positive, the pressure difference ΔPa is increased, and when the differential pressure component ΔPh is negative, the pressure difference ΔPa is decreased. Further, based on the differential pressure component ΔPh, the time Ta
And the pressure difference ΔPa may be adjusted.

In the first and second embodiments, a pressure sensor is disposed in a passage near the workpiece, and the time elapsed after the pressure detected by the pressure sensor reaches the initial pressure (corresponding to time T2 in FIG. 2). ) May be adjusted. This time adjustment is included in the adjustment of the time Ta.

The setting of the time Ta and the pressure difference ΔPx in the special test mode may be the same as in the normal test mode executed immediately before, as described above, or as a setting condition when the ambient temperature is at the standard temperature. Is also good.

In the first and second embodiments, the initial pressure and the test pressure may be made negative by using a negative pressure air source instead of the compressed air source. In this case, the same circuits as those in FIGS. 1 and 5 are used, but the pressure source side is defined as the upstream side. In this case, the adiabatic expansion when an initial pressure having an absolute value greater than the test pressure is applied lowers the air temperature in the work, and in the initial pressure applied state, the air temperature in the work increases toward the ambient temperature due to heat absorption. Then, the adiabatic heat of compression when the pressure is switched to the test pressure further raises the air temperature in the work to the ambient temperature.

[0037]

As described above, according to the first and second aspects of the present invention, in the normal test mode, the leak test can be executed in a short time by switching from the initial pressure to the test pressure, By adjusting the control conditions in this normal test mode in a special test mode that is performed as needed or periodically, accurate leak detection can be performed regardless of changes in the ambient temperature. Third and fourth aspects of the present invention
According to the aspect, even in a simple air leak test, the same operation and effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a differential pressure type air leak test apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a lapse of time of a workpiece pressure obtained by valve control in the same device.

FIG. 3 is a diagram showing a lapse of time of an in-work air temperature obtained by valve control in the apparatus.

FIG. 4 is a diagram showing a change in a detected differential pressure after closing an on-off valve, a change in a differential pressure component due to heat radiation, and a change in a differential pressure component due to leakage.

FIG. 5 is a circuit diagram of a simplified air leak test device according to a second embodiment of the present invention.

DESCRIPTION OF SYMBOLS 10 Pressure supply means 20 Common path 20 'path 21 Master side branch path 22 Work side branch path 27, 28 Open / close valve 29 Differential pressure sensor 29' Pressure sensor 30 Control means W Work

Claims (4)

[Claims] 1. A pressure supply means capable of supplying a test pressure and an initial pressure having an absolute value greater than the test pressure, a common passage connected to the pressure supply means, a master-side branch passage branched from the common passage, and Air leak using an apparatus including a work-side branch passage, an on-off valve provided in these branch passages, and a differential pressure sensor for detecting a differential pressure between the master-side and work-side branch passages downstream of these on-off valves. In the test method, in a normal test mode, the initial pressure is supplied from the pressure supply means to the master-side and work-side branch passages via the common passage, and then the test pressure is supplied. After being closed, the master-side and work-side branch passages are closed in an independent state. After waiting for a predetermined waiting time in this closed state, the work-side branch passage is determined based on the differential pressure detected by the differential pressure sensor. Detects the leakage of the work connected to the tester, and executes a special test mode as necessary or periodically. In this special test mode, the initial pressure supply and the test are performed in the same manner as the normal test mode. After supplying pressure and closing the on-off valve, after waiting for a longer waiting time than in the normal test mode, subtract the differential pressure component that changes linearly due to leakage from the differential pressure detected by the differential pressure sensor. The time from the start of the initial pressure supply in the normal test mode to the switch to the test pressure, the pressure difference between the initial pressure and the test pressure, so that the differential pressure component that does not change is obtained, and the differential pressure component that does not change becomes zero. Adjusting one or both of the above methods. 2. A pressure supply means capable of supplying a test pressure and an initial pressure having an absolute value greater than the test pressure, a common passage connected to the pressure supply means, a master-side branch passage branched from the common passage, and An air leak including a work-side branch passage, an on-off valve provided in these branch passages, a differential pressure sensor for detecting a differential pressure between the master-side and work-side branch passages downstream of these on-off valves, and control means. In the test apparatus, the control means controls the pressure supply means in a normal test mode to supply the initial pressure to the master-side and work-side branch passages via the common passage,
Next, a test pressure is supplied. Thereafter, the on-off valve is closed, and the branch passages on the master side and the work side are closed independently. After waiting for a predetermined waiting time in this closed state, the branch pressure is detected by the differential pressure sensor. Detecting the leakage of the work connected to the work-side branch passage from the differential pressure, the control unit also executes a special test mode. In this special test mode, the control unit performs the same operation as the normal test mode. After the initial pressure supply and the test pressure supply are performed and the on-off valve is closed, and after waiting for a longer waiting time than in the normal test mode, the pressure difference linearly changes due to leakage from the differential pressure detected by the differential pressure sensor. Subtract the differential pressure component,
Obtain a differential pressure component that does not change, and set the time between the start of the initial pressure supply in the normal test mode and the switch to the test pressure, the difference in pressure between the initial pressure and the test pressure so that the differential pressure component that does not change becomes zero. An air leak test apparatus characterized by adjusting one or both of them. 3. A pressure supply means capable of supplying a test pressure and an initial pressure having an absolute value greater than the test pressure, a passage connecting the pressure supply means and the work, an on-off valve closing the passage, and an on-off valve. An air leak test method using a device equipped with a pressure sensor for detecting a pressure in a passage downstream of the device. In a normal test mode, the initial pressure is applied to the work through the passage by controlling the pressure supply means. A pressure is supplied, then a test pressure is supplied, and then the work is closed by closing the on-off valve, and after waiting for a predetermined waiting time in the closed state, the leakage of the work is detected from the pressure detected by the pressure sensor. Detect and execute a special test mode as needed or periodically. In this special test mode, the initial pressure supply and test pressure supply are performed in the same manner as the normal test mode. After closing the on-off valve I, after waiting for a longer latency than the normal test mode, the detected pressure of the pressure sensor, by subtracting the pressure component which varies linearly due to leakage,
The time from the start of the initial pressure supply in the normal test mode to the switch to the test pressure, or the pressure difference between the initial pressure and the test pressure so that the pressure component that does not change is obtained and the pressure component that does not change becomes zero. An air leak test method, characterized in that one or both are adjusted. 4. A pressure supply means capable of supplying a test pressure and an initial pressure having an absolute value greater than the test pressure, a passage connecting the pressure supply means and the work, an on-off valve closing the passage, and an on-off valve An air leak test apparatus comprising a pressure sensor for detecting a pressure in a passage downstream of the air conditioner, and a control unit, wherein the control unit controls the pressure supply unit in a normal test mode, thereby controlling the pressure supply unit through the passage. To supply the initial pressure to the workpiece, and then to supply the test pressure, then close the on-off valve to close the workpiece, wait for a predetermined waiting time in this closed state, and then detect the pressure detected by the pressure sensor. The control means also executes a special test mode. In this special test mode, the initial pressure supply is performed similarly to the normal test mode. , After closing the opening and closing valve tested pressure supply, after waiting the latency than the normal test mode, the detected pressure of the pressure sensor, by subtracting the pressure component which varies linearly due to leakage,
The time from the start of the initial pressure supply in the normal test mode to the switch to the test pressure, or the pressure difference between the initial pressure and the test pressure so that the pressure component that does not change is obtained and the pressure component that does not change becomes zero. An air leak test apparatus characterized in that one or both are adjusted.