Method for adjusting fan placement for gas leak testing

Abstract

To ensure measurement reproducibility in a gas leakage test even if a test object is large or has a complex geometry.SOLUTION: In the gas leakage test, a test object W is set in a predetermined position and a chamber 30 is sealed, a tracer gas is supplied to the test object W, the tracer gas leaking from the test object W into the chamber 30 is diffused by agitating air inside the chamber 30 with a fan 35 arranged in the chamber 30, and the tracer gas in the air inside the chamber 30 is measured by a gas measuring instrument 52 to determine whether the test object W is good or bad. As a preparatory step for the gas leakage test, a fan arrangement adjustment process is performed. A leakage-free model object Ws of the same configuration as the test object W is set inside the chamber 30, and pseudo-leakage devices 60 are sequentially arranged in the vicinity of multiple sites P1-P4 of the model object Ws. A process similar to the gas leakage test is performed, the tracer gas is made to leak from the pseudo-leakage device 60, so that a measurement value for each of the multiple sites P1-P4 is obtained, and the arrangement of the fan 35 is adjusted on the basis of these measurement values.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for adjusting the arrangement of a fan in a chamber for a leak test using a tracer gas such as hydrogen.

Background Art

[0002] In the gas leak test method disclosed in Patent Document 1, a hollow test object is placed in a chamber at atmospheric pressure, a tracer gas such as hydrogen is supplied to the test object, and a gas measuring instrument connected to the chamber measures the tracer gas leaked from the test object into the air in the chamber. If the measured value exceeds a threshold value, it is determined that there is a defect in the test object.

[0003] In the gas leak test method of Patent Document 1, since the inside of the chamber is at atmospheric pressure, the device can be manufactured at a low cost without requiring high strength. However, since the diffusion of the leaked tracer gas is insufficient, the tracer gas cannot be accurately measured in a short time. Therefore, the air in the chamber is stirred by a fan arranged in the chamber to promote the diffusion of the tracer gas leaked from the test object.

Prior Art Documents

Patent Documents

[0004] <开,

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method described in Patent Document 1, when the test object is small and has a simple shape, the tracer gas diffuses well, allowing for quick measurement of a value corresponding to the size of the defect, regardless of the location of the defect (the location of the tracer gas leakage) in the test object (ensuring measurement reproducibility). However, when the test object is large or has a complex shape, the way the tracer gas leaks from multiple defect locations in the test object diffuses can vary greatly depending on the fan arrangement, and the measurement values ​​from the gas measuring instrument may differ even if the defect size is the same (ensuring measurement reproducibility). As a result, there is a risk of misjudging whether the test object is good or bad. [Means for solving the problem]

[0006] The present invention was made to solve the above-mentioned problems, and as a preparatory step for a gas leak test, a hollow test object is set in a predetermined position in a chamber, the chamber is sealed, tracer gas is supplied to the test object, the air in the chamber is stirred by at least one fan placed in the chamber to diffuse the tracer gas leaking from the test object into the chamber, the tracer gas in the air in the chamber is measured by a gas measuring instrument connected to the chamber, and if the measured value exceeds a threshold, it is determined that the test object is defective. The method is characterized by setting a leak-free model object having the same configuration as the test object in a predetermined position within the chamber, sequentially arranging dummy leakers near a selection of multiple parts of the model object, leaking the tracer gas from the dummy leaker into the chamber for each of the multiple parts, agitating the air in the chamber with the fan, measuring the tracer gas with the gas measuring instrument, and adjusting the fan's position based on the measured values ​​for each of the multiple parts. This method allows for good diffusion of the tracer gas by adjusting the fan placement, even if the test object is large or complex, or if the location of the defect (the location of the tracer gas leakage) differs. As a result, in gas leak tests, measurement values ​​corresponding to the defect can be obtained regardless of the location of the defect (the location of the tracer gas leakage) in the test object (reproducibility can be ensured), and the quality of the test object can be accurately determined.

[0007] The adjustment of the fan arrangement includes adjusting at least one of the fan's airflow, direction, position, or number. Preferably, a plurality of fans are arranged within the chamber.

[0008] In one embodiment, the simulated leak device communicates with the internal space of the model object via a passage means outside the model object, and the tracer gas inside the model object is leaked out of the simulated leak device through the passage means. This method simulates leakage in the vicinity of the simulated leak device, allowing the fan placement to be adjusted without modifying the model object.

[0009] Preferably, the passage means includes a flexible tube. This method allows for the smooth sequential transfer of the simulated leak device to multiple different locations on the model object.

[0010] More preferably, the chamber is provided with a main coupler and a sub-coupler, and the gas supply passage extending from the tracer gas source is branched downstream into a main passage connected to the main coupler and a sub-passage connected to the sub-coupler, the model object is connected to the main coupler within the chamber, and the simulated leak device is connected to the sub-coupler within the chamber via the flexible pipe.

[0011] More preferably, the dummy leak device is detachably attached to the outer surface of the model object by temporary fastening means.

[0012] In another embodiment, the dummy leak devices are attached to a selection of outer surfaces of the model object, and the leak passages of the dummy leak devices are connected to holes formed in the wall of the model object, causing the tracer gas inside the model object to leak into the chamber through the holes in the model object and the leak passages of the dummy leak devices. This method allows for the direct leakage of tracer gas from the model object, thus simplifying the pathway configuration. [Effects of the Invention]

[0013] According to the present invention, even if the test object is large or complex, the tracer gas leaking from the test object can be measured with high reproducibility regardless of the location of defects in the test object, and the quality of the test object can be accurately determined. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a gas leak test apparatus capable of performing the fan arrangement adjustment method according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram of the inside of the chamber showing the fan arrangement adjustment method of the first embodiment. [Figure 3] This figure corresponds to Figure 2, showing a fan arrangement adjustment method according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, a first embodiment of the method of the present invention will be described with reference to the drawings. <Configuration of the gas leak test apparatus> First, a gas leak test apparatus to which the present invention method is applied will be described with reference to Figure 1. The gas leak test apparatus comprises a gas supply passage 10, a tracer gas source 20 connected to the upstream end of the gas supply passage 10, and a chamber 30 connected to the downstream end of the gas supply passage 10.

[0016] The tracer gas source 20 has a gas cylinder 21, a cylinder-side regulator 22, and a main valve 23. The gas cylinder 21 is filled with a pressurized tracer gas of 5% hydrogen and 95% nitrogen. In the gas supply passage 10, a test pressure regulator 11, a normally closed supply valve 12, and a pressure switch 13 are provided in order from the upstream side to the downstream side.

[0017] An exhaust passage 40 is connected to the downstream side of the supply valve 12 in the gas supply passage 10. The exhaust passage 40 has a first branch portion 41 and a second branch portion 42. A normally closed first exhaust valve 43 is provided in the first branch portion 41, and a normally closed second exhaust valve 44 and a vacuum pump 45 are provided in the second branch portion 42. The downstream end of the gas supply passage 10 is branched into a main passage portion 15 and a sub-passage portion 16.

[0018] The chamber 30 is openable and closable and has a main coupler 31 and a sub-coupler 32 on its side wall. The main passage portion 15 of the gas supply passage 10 is connected to the main coupler 31, and the sub-passage portion 16 is connected to the sub-coupler 32.

[0019] An internal passage 33 is arranged in the chamber 30, and one end of this internal passage 33 is connected to the main coupler 31. A hollow test object W having a sealed space is set at a predetermined position in the chamber 30. The test object W is detachably connected to the other end of the internal passage 33. Further, a plurality of fans 35 are arranged in the chamber 30.

[0020] In the fan arrangement adjustment process described later, a pseudo leak detector 60 described later is arranged in the chamber 30, and this pseudo leak detector 60 is connected to the sub-coupler 32 via a flexible tube 65. However, in the normal gas leak test process, the pseudo leak detector 60 is not arranged in the chamber 30, and the flexible tube 65 is not connected to the sub-coupler 32, so the sub-coupler 32 is in a closed state.

[0021] [[ID=IPD=19]] The chamber 30 is further provided with a measurement coupler 36. The upstream end of the measurement passage 50 is connected to this measurement coupler 36. A normally closed measurement valve 51 is provided in this measurement passage 50, and a gas measuring instrument 52 for measuring hydrogen is connected to the downstream end. A cleaning passage 55 is connected between the measurement valve 51 and the gas measuring instrument 52. A normally open cleaning valve 56 is provided in this cleaning passage 55.

[0022] <Normal gas leak test process> First, the normal gas leak test process will be described. In this process, the dummy leak detector 60 and the flexible tube 65 are not arranged in the chamber 30. The test object W is set at a predetermined position in the chamber 30, connected to the internal passage 33, and the chamber 30 is sealed. The air pressure in the chamber 30 is at atmospheric pressure.

[0023] Next, by the sequence control of a controller (not shown), the following gas leak test process is executed. The supply valve 12 is opened to supply a tracer gas at a test pressure to the test object W. At the time when a predetermined time has elapsed, it is confirmed by the pressure switch 13 that the pressure in the test object W has reached the test pressure, the supply valve 12 is closed, and a predetermined time is waited.

[0024] During the above waiting time, the air in the chamber 30 is stirred by the fan 35. If there is a defect in the test object W, the tracer gas in the test object W leaks into the chamber 30 and diffuses in the chamber 30 by the stirring by the fan 35. It is preferable that the operation of the fan 35 continues also in the measurement stage described later. Also, the operation may be started before the waiting time.

[0025] Measurement is performed for a predetermined time from the end of the above waiting period. That is, the cleaning valve 56 is closed and the measurement valve 51 is opened. As a result, the air in the chamber 30 is sent to the gas measuring instrument 52 by a continuously operating pump built into the gas measuring instrument 52. If the test subject W is defective and the tracer gas diffuses into the air in the chamber 30, the hydrogen in the tracer gas is measured by the gas measuring instrument 52. The measurement value from the gas measuring instrument 52 is sent to the controller. The controller determines that the test subject W is defective if the measurement value exceeds the threshold, and determines that it is a good product if it is below the threshold.

[0026] After the measurement is complete, the measurement valve 51 is closed and the cleaning valve 56 is opened. This allows air from the atmosphere to pass through the cleaning passage 55 and then through the gas measuring instrument 52, thereby cleaning the gas measuring instrument 52.

[0027] By opening the first exhaust valve 43 at approximately the same time as the above cleaning process, the tracer gas inside the test subject W is discharged outdoors via the first branch 41 of the exhaust passage 40. Furthermore, by closing the first exhaust valve 43 and opening the second exhaust valve 44, the tracer gas inside the test subject W is sucked in by the vacuum pump 45 and discharged outdoors via the second branch 42 of the exhaust passage 40.

[0028] After the above gas leak test is completed, the chamber 30 is opened and the test subject W is removed, and a new test subject W is connected to the internal passage 33 and the gas leak test is resumed.

[0029] <Fan placement adjustment process> In the gas leak test described above, the internal pressure of the chamber 30 is approximately atmospheric pressure, so high strength is not required for the chamber 30, and the manufacturing cost of the device can be reduced. The fan 35 stirs the air inside the chamber 30 and plays a role in homogenizing the concentration of the tracer gas leaked from the defect in the test object W. As a result, regardless of where the defect is located in the test object W, the gas measuring instrument 52 can measure hydrogen gas with good reproducibility corresponding to the size of the defect. However, the test object W is not always a simple shape as schematically shown in Figure 1. For example, if the test object W is large or has a complex shape, depending on the arrangement of the fan 35, the tracer gas may not diffuse uniformly, and the measured values ​​may differ even if the size of the defect is the same (i.e., the amount of tracer gas leaked is the same). Therefore, prior to the standard gas leak test described above, the placement of the fan 35 is optimized for each test target W of various shapes as a preparatory step to improve reproducibility.

[0030] As shown in Figure 2, in the fan placement adjustment process, a simulated leak device 60 having a known orifice (leakage passage) is connected to the sub-coupler 32 via a flexible tube 65. A good sample of the test subject, i.e., a model subject Ws with the same configuration as the test subject and confirmed to be leak-free, is set in a predetermined position in the chamber 30 and connected to the internal passage 33, in the same manner as in the normal gas leak test process.

[0031] Multiple locations P1 to P4 are pre-selected for the model target Ws. These locations P1 to P4 may be areas prone to defects, or areas where tracer gas does not easily diffuse when leaked. The simulated leak detector 60 is sequentially placed near parts P1 to P4. In this embodiment, it is temporarily fixed to the outer surface of these parts P1 to P4 with tape (temporary fixing means). For example, in the first fan position adjustment step, the simulated leak detector 60 is installed at part P1.

[0032] Once the model object Ws and the simulated leak device 60 are installed, the chamber 30 is sealed, and the controller performs the same sequence control as a normal gas leak test. During the standby phase after the supply valve 12 (see Figure 1) is closed, the tracer gas does not leak directly from the model object Ws into the chamber 30, but leaks into the chamber 30 through the orifice of the simulated leak device 60 via the passage means consisting of the internal passage 33, main passage section 15, sub-passage section 16, and flexible pipe 65. This leakage of tracer gas from the simulated leak device 60 simulates leakage from the part P1 on the model object Ws where the simulated leak device 60 is installed. The leaked tracer gas is diffused by the fan 35. The tracer gas resulting from this simulated leak is measured by the gas measuring instrument 52.

[0033] The system determines whether the measured values ​​above match within an acceptable range with the predicted leakage amount of the known simulated leak device 60 and the predicted measured values ​​derived from the volume of the chamber 30, etc. If they do not match, the arrangement of the fans 35 is adjusted. Adjusting the arrangement of the fans 35 includes adjusting at least one of the fan volume, direction, position, or number of fans 35. For example, the position, direction, air volume, etc. of the fan 35 closest to part P1 is adjusted, or a new fan 35 is installed near part P1. The same process is repeated after the adjustment. If the measured values ​​of the gas measuring instrument 52 match within an acceptable range with the predicted measured values, the adjustment of the fan arrangement of 35 at part P1 is completed.

[0034] Next, the simulated leak device 60 is sequentially moved to locations P2, P3, and P4 of the model target Ws and temporarily fixed in place, and the same fan placement adjustment process is performed to optimize the placement of the fan 35. Since the simulated leak device 60 is connected to the flexible pipe 65, these moves can be performed smoothly.

[0035] As described above, even if the test object W is large or has a complex shape, by adjusting the placement of the fan 35 as described above, the placement of the fan 35 is optimized so that the tracer gas is uniformly diffused regardless of the leakage location of the test object W during the gas leak test process. Therefore, the measured values ​​of the tracer gas generated by defects at different locations on the test object W can be correlated with the size of the defect (amount of tracer gas leakage), ensuring reproducibility. As a result, the quality of the test object W can be accurately determined. In this embodiment, no processing is required on the model target Ws.

[0036] <Second Embodiment> Next, a second embodiment of the fan placement adjustment process will be described. In the first embodiment shown in Figure 2, the orifice of the simulated leak device 60 is connected to the model object Ws via a passage means consisting of an internal passage 33, a main passage section 15, a secondary passage section 16, and a flexible pipe 65. In contrast, in the second embodiment shown in Figure 3, the downstream end of the gas supply passage 10 is not branched and is connected to the main coupler 31. There is no secondary passage section 16 and flexible pipe 65, and the simulated leak device 60 is directly attached to the outer surface of the model object Ws by means of adhesive or other means, ensuring airtightness. The orifice of the simulated leak device 60 is connected to the internal space of the model object Ws via a hole (not shown) formed in the wall of the model object Ws. In this embodiment, since the simulated leak device 60 is connected to the model object Ws without passing through a passage means outside the model object Ws, the passage configuration can be simplified compared to the second embodiment.

[0037] Holes are pre-formed in all parts P1 to P4 of the model object Ws. When adjusting the fan placement for one part, a simulated leak device 60 is installed in that part, and the other parts are blocked by a blocking means (not shown). Tracer gas from the gas supply passage 10 is supplied to the model object Ws via the internal passage 33. Tracer gas from the model object Ws leaks into the chamber 30 via the simulated leak device 60. The rest is the same as in the first embodiment, so the explanation is omitted.

[0038] In the second embodiment, model targets Ws are prepared in the same number as the selected parts P1 to P4, and each model target Ws has a hole in one of the different parts P1 to P4, and a simulated leak device 60 may be attached to these parts. In this case, the model targets Ws are replaced at each fan placement adjustment step for each part.

[0039] The present invention is not limited to the embodiments described above, and various modifications can be made without departing from its spirit. A gas containing helium may be used as the tracer gas. The leak passage of the dummy leak detector may be a pinhole formed in a thin plate. A single fan is sufficient. In this case, at least one of the fan's airflow, direction, or position can be adjusted. [Industrial applicability]

[0040] The present invention can be applied to gas leak testing methods. [Explanation of symbols]

[0041] 10 Gas supply passage 11 Main passage section 12 Sub-passage section 20 Tracer gas sources 30 Chambers 31 Main coupler 32 Sub-coupler 35 Fans 52 Gas measuring instruments 60 Pseudo-leakage device 65 Flexible pipe (passage means) W Test Subject Ws Model Target

Claims

1. As a preparatory step for a gas leak test, a hollow test object is placed in a predetermined position within a chamber, the chamber is sealed, tracer gas is supplied to the test object, the air inside the chamber is agitated by at least one fan placed inside the chamber to diffuse the tracer gas leaking from the test object into the chamber, the tracer gas in the air inside the chamber is measured by a gas measuring instrument connected to the chamber, and if the measured value exceeds a threshold, it is determined that the test object is defective. A method characterized by setting a leak-free model object having the same configuration as the test object in a predetermined position within the chamber, sequentially arranging dummy leak devices near a plurality of selected parts of the model object, leaking the tracer gas from the dummy leak device into the chamber for each of the plurality of parts, agitating the air in the chamber with the fan, measuring the tracer gas with the gas measuring instrument, and adjusting the arrangement of the fan based on the measured values ​​for each of the plurality of parts.

2. The method according to claim 1, characterized in that the adjustment of the arrangement of the fans includes adjusting at least one of the airflow, direction, position, and number of fans.

3. The method according to the 2, characterized in that a plurality of the fans are arranged inside the chamber.

4. The method according to the 2, characterized in that the simulated leak device communicates with the internal space of the model object via a passage means outside the model object, and the tracer gas inside the model object is leaked out of the simulated leak device via the passage means.

5. The method according to 4, characterized in that the passage means includes a flexible pipe.

6. The method according to 5, wherein the chamber is provided with a main coupler and a sub-coupler, the gas supply passage extending from the tracer gas source is branched downstream into a main passage connected to the main coupler and a sub-passage connected to the sub-coupler, the model object is connected to the main coupler within the chamber, and the simulated leak device is connected to the sub-coupler within the chamber via the flexible pipe.

7. The method according to any one of 4 to 6, characterized in that the simulated leak device is detachably fixed to the outer surface of the model object by temporary fixing means.

8. The method according to 2, characterized in that the dummy leak devices are attached to a plurality of selected outer surfaces of the model object, the leak passages of the dummy leak devices are connected to holes formed in the wall of the model object, and the tracer gas inside the model object is leaked into the chamber through the holes in the model object and the leak passages of the dummy leak devices.

Images