Leakage test method and apparatus

Abstract

To heighten reliability and detection sensitivity and shorten a test time in a leak test in which a low-pressure detection object gas from a chamber or a specimen is introduced into an inspection component sensor placed under pressure appropriately equivalent to the atmospheric pressure.SOLUTION: An inspection gas including an inspection component (H2) is introduced into the internal space (first room 11) of a specimen 9 that is accommodated in a chamber 10. The pressure of an in-chamber space (second room 12) between the chamber 10 and the specimen 9 is reduced. An inspection object gas g in the second room 12 is circulated along a circulation path 30 composed of a reciprocating path 31 and the second room 12. Thereafter, the circulation is stopped and the inspection object gas g is compressed toward a sensor introduction path 49 branched from the circulation path 30 by a compressed gas (clean air) from a compressed gas supply channel 53. The compressed inspection object gas g is introduced into the inspection component sensor 43.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for performing a leak test on a specimen (workpiece) using a test gas containing a test component such as hydrogen, and particularly to a leak test method and an apparatus for introducing a low-pressure test gas from the specimen or a chamber containing the specimen into a test component sensor placed under a pressure such as atmospheric pressure to detect the test component.

Background Art

[0002] As this type of leak test, for example, in a hydrogen leak test, the specimen is placed in a chamber, a test gas containing hydrogen is introduced into the inside of the specimen, and the space inside the chamber between the inner wall of the chamber and the specimen is depressurized, and hydrogen in the test gas in the space inside the chamber is detected by a hydrogen sensor (see Patent Documents 1, 2, etc.). As the hydrogen sensor, for example, a semiconductor-type hydrogen sensor is used. Oxygen in the air is adsorbed on the surface of the semiconductor of the semiconductor-type hydrogen sensor. When hydrogen flows in there, the above oxygen and hydrogen react and the amount of adsorbed oxygen decreases, and the electrical conductivity (current) of the semiconductor changes, so that hydrogen can be detected. On the other hand, since the semiconductor-type hydrogen sensor requires oxygen in the air, it is placed under atmospheric pressure. Even if the hydrogen concentration in the test gas is high in the depressurized space inside the chamber, when the test gas is introduced into the semiconductor-type hydrogen sensor, if air at atmospheric pressure is mixed, the hydrogen concentration is diluted and the sensitivity decreases.

[0003] In Patent Document 1, the test gas is pushed out from a vacuum chamber with a carrier gas composed of air or nitrogen, and is drawn into a vacuum pump and compressed to atmospheric pressure and discharged, thereby introducing the test gas into a hydrogen sensor under atmospheric pressure. In Patent Document 2, the test gas is pushed out from a vacuum chamber with a small flow rate of clean air (carrier gas), and the test gas is compressed with a large flow rate of clean air and introduced into a hydrogen sensor under atmospheric pressure.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-164525 [Patent Document 2] Japanese Patent Publication No. 2015-161555 [Overview of the project] [Problems that the invention aims to solve]

[0005] The method described in Patent Document 1 detects hydrogen in the test gas after it has passed through a vacuum pump. This can compromise the reliability of the leak test because hydrogen may dissolve into the sealing oil of the vacuum pump or be affected by the pulsation of the vacuum pump. Using a dry pump eliminates the need for sealing oil, but it is expensive and increases the product price. Furthermore, mixing with the carrier gas dilutes the hydrogen concentration of the test gas, reducing sensitivity. Even with the method described in Patent Document 2, there is a concern about dilution of the test gas because a carrier gas is used. To avoid this, it is necessary to make the pipeline (compression path) extending from the vacuum chamber to the hydrogen sensor long and narrow so that the test gas and carrier gas do not mix during the compression process. However, this would require time to guide the test gas into the compression path with a small flow rate of carrier gas, which in turn would lengthen the test time. In view of these circumstances, the present invention aims to improve the reliability and detection sensitivity of leak tests in which a low-pressure test gas from a test subject or a chamber containing it is introduced into a test component sensor placed under atmospheric pressure or other pressure to detect test components such as hydrogen, and to shorten the test time. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a leak test method for testing a sample using a test gas containing a test component, The process involves introducing the test gas into the first chamber, which is one of two chambers consisting of the internal space of the subject housed in the chamber and the chamber space between the chamber and the subject. A step of reducing the pressure in the second chamber, A step of circulating the gas to be tested in the second chamber along a circulation path consisting of a return path with both ends connected to the second chamber and the depressurized second chamber, The process involves stopping the circulation and compressing the gas to be tested with compressed gas towards a sensor introduction path branched off from the circulation path, The process involves introducing the compressed gas to be tested through the sensor introduction path to a test component sensor under approximately atmospheric pressure or high pressure from the second chamber, and detecting the test component. It is characterized by having the following features. Examples of the components tested include hydrogen gas (H2). Examples of the aforementioned test component sensors include semiconductor hydrogen sensors. Semiconductor hydrogen sensors are typically placed under approximately atmospheric pressure and at least under a higher pressure than the second chamber. In addition, if there is leakage from the sample, the leaked test component will accumulate in the circulating test gas during the circulation process, increasing the concentration of the test component in the test gas. If the test sample has a sealing defect, the test gas introduced into the first chamber will leak into the second chamber through the sealing defect. The aforementioned circulation process creates a flow in the test gas in the second chamber, allowing test components such as H2 from leaked test gas to mix throughout the entire test gas. Therefore, once the circulation flow of the test gas is established, the concentration of test components in the test gas will remain constant, provided the leakage is constant. This not only provides the same effect as the carrier gas described in Patent Document 2, but also prevents dilution of the test component concentration because no carrier gas is introduced from the outside. Moreover, during the circulation process, leaked test components accumulate in the circulation path, increasing the concentration of test components. This enhances detection sensitivity. Furthermore, the circulation process allows the test gas to flow through the compression path in the compression process, from the second chamber to the branching point of the sensor introduction path in the return path. Additionally, increasing the capacity of the circulation pump used in the circulation process can increase the flow velocity of the test gas. As a result, the test gas can be introduced to the test component sensor at high speed during the detection process, eliminating the need to increase the flow velocity or flow rate of the carrier gas. This shortens the test time without compromising detection sensitivity during the inspection process. Incidentally, in carrier gas methods such as those described in Patent Documents 1 and 2, in order to quickly guide the test gas into the compression path, it is necessary to increase the flow velocity or the flow rate. Increasing the flow velocity requires narrowing the passage, but manufacturing a chamber tailored to the shape of the test sample is costly and difficult to handle in a wide variety of products. Therefore, the only option is to increase the flow rate, which leads to dilution of the test gas. Since the detection process can be performed before passing the test gas through the vacuum pump used for exhausting from the test component sensor, or without passing the test gas through the vacuum pump used for introducing it to the test component sensor, the test is not affected by the absorption of the test component by the oil in the vacuum pump or by the pulsation of the vacuum pump, thus increasing the reliability of the leak test.

[0007] Preferably, in the stopping and compression steps, a portion of the return path downstream of the branch to the sensor introduction path is blocked, and the compressed gas is supplied to the downstream side of the blocked portion of the return path. This allows the gas to be compressed toward the sensor introduction path while maintaining the flow direction of the gas to be tested in the circulation step.

[0008] The present invention is a leak testing apparatus that performs a leak test on a sample using a test gas containing a test component, A chamber for containing the subject, A test gas introduction path connected to the first chamber, which is one of the two chambers consisting of the internal space of the subject and the chamber space between the chamber and the subject, A pressure reducing pump connected to the second chamber, A return path that connects to the second chamber at both ends and forms a circulating path, A circulation pump that circulates the gas to be tested in the second chamber along the circulation path, A sensor introduction path branched off from the aforementioned circulation path, A compressed gas supply path supplies compressed gas to the circulation path so that the gas to be tested after circulation is compressed toward the sensor introduction path, A test component sensor connected to the aforementioned sensor introduction path and positioned under approximately atmospheric pressure or a pressure higher than the second chamber, It is characterized by having the following features.

[0009] Preferably, in the reciprocating path, a branch portion to the sensor introduction path, the circulation pump, and a confluence portion with the compressed gas supply path are sequentially provided from the upstream side.

[0010] Preferably, the chamber has an upstream wall portion and a downstream wall portion along the circulation path, and at least one of these wall portions has a connection port to the end of the reciprocating path, a wall inner space portion that is continuous with the connection port and extends in the in-plane direction of the one wall portion, a plurality of openings that are respectively continuous with the wall inner space portion and are arranged to be dispersed from each other in the in-plane direction of the wall portion, and the openings are opened into the chamber inner space while expanding from the wall inner space portion. Thereby, the retention of the test gas in the chamber can be prevented, and the reliability of the leak test is further enhanced. This configuration is suitable when the chamber inner space is the second chamber.

Advantages of the Invention

[0011] According to the present invention, in a leak test for introducing a low-pressure test gas from a chamber or a test object into an inspection component sensor placed under a pressure such as approximately atmospheric pressure to detect an inspection component, the reliability and detection sensitivity can be enhanced, and the test time can be shortened.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a circuit diagram of a leak test apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a chart showing the operation of the leak test apparatus. [Figure 3] FIG. 3 is a circuit diagram of a leak test apparatus according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a chart showing the operation of the leak test apparatus according to the second embodiment. [Figure 5]FIG. 5 is a cross-sectional view of the chamber of the leak test apparatus according to the third embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view of the chamber of the leak test apparatus according to the fourth embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. <First Embodiment (FIGS. 1 to 2)> FIG. 1 shows a leak test apparatus 1 for performing a leak test on a test object 9 using an inspection gas. The test object 9 is not particularly limited and can be applied to parts or products in various fields such as mechanical elements, electronic components, and microdevices.

[0014] The leak test apparatus 1 includes a chamber 10, an inspection gas introduction system 20, a reciprocating path 31, and a leak detection unit 40. The test object 9 is accommodated in the chamber 10. The test object 9 preferably has an internal space. The internal space may be a sealed space or may be open. The opening of the test object 9 may be sealed by the bottom surface or the like of the chamber 10 to seal the internal space. Either the chamber internal space between the inner surface of the chamber 10 and the test object 9 or the internal space of the test object 9 constitutes a "first chamber 11", and the other constitutes a "second chamber 12". Here, the internal space of the test object 9 constitutes the first chamber 11, and the chamber internal space constitutes the second chamber 12. The two chambers 11 and 12 are each sealed.

[0015] A test gas introduction system 20 is connected to the first chamber 11. The test gas introduction system 20 includes a test gas source 21 that stores the test gas and a test gas introduction passage 22. The test gas contains hydrogen (H2), which is the test component, and nitrogen (N2), which is the diluent component. The hydrogen concentration (H2 / (H2+N2)) in the test gas is preferably around a few percent, more preferably around 5%. The test gas introduction passage 22 extends from the test gas source 21 to the first chamber 11. The test gas introduction passage 22 is equipped with a regulator (pressure reducing valve) 23, a pressure gauge 24, and a normally closed electromagnetic valve 25, in order from the test gas source 21.

[0016] Downstream of the electromagnetic valve 25, the inspection gas introduction passage 22 is joined by the cleaning passage 3, the open passage 4, and the exhaust passage 5. The cleaning passage 3 is equipped with a regulator (pressure reducing valve) 3A, a pressure gauge 3B, and a normally closed electromagnetic valve 3V, in order from the upstream side. The open passage 4 is equipped with a normally open electromagnetic valve 4V. The exhaust passage 5 is equipped with a normally closed electromagnetic valve 5V and an exhaust pump 5P, in order from the side where it merges with the introduction passage 22.

[0017] The second chamber 12 is connected to both ends 31a and 31b of the return path 31. Preferably, the return path end 31a and the return path end 31b are located on opposing walls 13 and 14 of the chamber 10, and more preferably, they are located near diagonally opposite positions on the chamber 10. The second chamber 12 and the return path 31 constitute the circulation path 30.

[0018] The return path 31 is equipped with, in order from the upstream side (the side of the return path end 31a), a pressure gauge 33, a branch section 31c, a normally closed electromagnetic valve 34, an exhaust / circulation pump 35, an electromagnetic three-way valve 36, a junction section 31d, and a pressure gauge 37. The exhaust / circulation pump 35 serves as both a "pressure reducing pump" connected to the second chamber 12 and a "circulation pump" provided in the circulation path 30.

[0019] The three-way valve 36 is switchable between an open position 36a and an exhaust position 36b. When the three-way valve 36 is in the open position 36a, it connects the return paths 31 on both sides of the three-way valve 36. When the three-way valve 36 is in the exhaust position 36b, it opens the outlet port of the exhaust / circulation pump 35 to the atmosphere and closes the connection point between the three-way valve 36 and the return path 31 downstream of the three-way valve 36. By opening the on-off valve 34 and setting the three-way valve 36 to the open position 36a, the circulation path 30 is opened. By closing the on-off valve 34 and setting the three-way valve 36 to the exhaust position 36b, the portion 30d between these valves 34 and 36 in the circulation path 30 (a portion downstream of the branching section 31c) is blocked. Preferably, the length of the blockable portion 30d between the valves 34 and 36 in the actual device is made as short as possible.

[0020] A connecting path 39 branches off from branch section 31c. A leak detection unit 40 is connected to the connecting path 39.

[0021] The leak detection unit 40 is composed of a hydrogen leak detector and includes a detection path 41, an air supply path 42, an inspection component sensor 43, and two-stage solenoid three-way valves 44 and 45. The downstream end of the connecting path 39 is connected to the inlet port 41a of the detection path 41. The inspection component sensor 43 is provided in the detection path 41. The sensor introduction path 49 is formed by the connecting path 39 and the detection path 41 from the inlet port 41a to the inspection component sensor 43. The circulation path 3, including the second chamber 12, is connected to the inspection component sensor 43 via the sensor introduction path 49.

[0022] The inspection component sensor 43 is composed of a semiconductor hydrogen sensor. A throttle 41c is provided in the detection path 41 downstream of the inspection component sensor 43. An exhaust path 46 extends from the outlet port 41b of the detection path 41. An exhaust pump 47 is connected to the exhaust path 46.

[0023] An air supply passage 42 is joined to the detection passage 41 via a solenoid three-way valve 45 in the portion immediately upstream of the inspection component sensor 43. The three-way valve 45 selectively connects either the detection passage 41 upstream of it or the air supply passage 42 to the inspection component sensor 43. The air supply passage 42 is provided with a throttle 42a and a filter 42b from the upstream side, and a relief passage 42c that prevents backflow is branched off from it.

[0024] An electromagnetic three-way valve 44 is provided at the upstream end of the air supply passage 42. The three-way valve 44 selectively connects either the calibration passage 48 or the clean air passage 50 to the air supply passage 42. A calibration test gas source 48a with a precisely controlled hydrogen concentration is provided at the upstream end of the calibration passage 48.

[0025] A clean air inlet 50a is provided at the upstream end of the clean air passage 50. A regulator (pressure regulating valve) 51 and a pressure gauge 52 are provided in the clean air passage 50, in order from the side of the clean air inlet 50a. The secondary pressure of the regulator 51 is set to a pressure slightly higher than atmospheric pressure, for example, about 50 kPa (gauge pressure). Consequently, the inspection component sensor 43 is positioned under approximately atmospheric pressure and at least under a pressure higher than that of the second chamber 12 during depressurization. Here, approximately atmospheric pressure refers to a range of about 0.8 to 1.2 times standard atmospheric pressure (101.3 kPa (absolute pressure)).

[0026] From the clean air passage 50 downstream of the pressure gauge 52, a connecting passage 50b to the air supply passage 42 and a compressed gas supply passage 53 are branched off. The compressed gas supply passage 53 extends to the circulation path 30. The compressed gas supply passage 53 is equipped with a variable throttle 54, two normally closed electromagnetic valves 55 and 57, and a compressed gas tank 56. The valves 55 and 57 are located downstream of the variable throttle 54. The compressed gas tank 56 is interposed between the valves 55 and 57. The downstream end of the compressed gas supply passage 53 is connected to the confluence 31d downstream of a portion 30d downstream of the branching section 31c in the circulation path 30.

[0027] <Leakage Test Method> The leak test device 1 operates as follows to perform a leak test on the sample 9. The subject 9 is placed in the chamber 10 (placement step). As shown in the chart in Figure 2, by demagnetizing (solenoid off) the electromagnetic three-way valves 44 and 45 of the leak detection unit 40, clean air from the clean air introduction unit 50a passes sequentially through the clean air passage 50, the communication passage 50b, and the air supply passage 42. Along the way, the flow rate is restricted by the throttle 42a, and any excess flow rate is released into the relief passage 42c before being supplied to the inspection component sensor 43 (air supply process). As a result, the inspection component sensor 43 is always positioned under approximately atmospheric pressure. Oxygen from the clean air is constantly adsorbed onto the semiconductor surface of the inspection component sensor 43. After passing through the inspection component sensor 43, the clean air passes through the throttle 41c, which determines the flow rate after the release, and is led to the exhaust passage 46, where it is exhausted by the exhaust pump 47. Note that the horizontal axis in Figure 2 is divided into equally spaced sections according to the order of the processes, and the length does not represent elapsed time.

[0028] Next, the on-off valve 4V of the open passage 4 is closed, and the on-off valve 5V of the exhaust passage 5 is opened, thereby drawing in and exhausting the gas from the first chamber 11 (the internal space of the subject 9) using the exhaust pump 5P (first chamber exhaust process). Simultaneously, the on-off valve 34 of the return path 31 is opened, the three-way valve 36 is set to the exhaust position 36b, and the gas in the second chamber 12 (the space inside the chamber) is evacuated and exhausted by the exhaust / circulation pump 35. As a result, the pressure in the second chamber 12 is reduced (second chamber depressurization process). Furthermore, the on / off valve 55 is opened, and compressed gas consisting of clean air is stored in the tank 56 (compressed gas storage process).

[0029] Subsequently, the on-off valve 5V is closed to shut off the vacuum pump 5P and the first chamber 11, and the on-off valve 25 of the test gas introduction passage 22 is opened to introduce the test gas from the test gas source 21 into the first chamber 11 (the internal space of the test subject 9) (test gas introduction process). The first chamber 11 becomes higher pressure than the second chamber 12. If the test subject 9 has a sealing defect, the test gas leaks through that sealing defect into the lower-pressure second chamber 12 (the space inside the chamber). As a result, the test gas mixes with the test gas g in the second chamber 12. In other words, the test gas g contains air remaining in the second chamber 12 even after the depressurization process, and the test component (H2) of the test gas in particular.

[0030] Next, the return path 31 is opened by setting the electromagnetic three-way valve 36 to the open position 36a while maintaining the open state of the electromagnetic on-off valve 34. This opens the circulation path 30. As a result, the gas g to be tested in the circulation path 30, including the second chamber 12 (the space inside the chamber), is circulated along the circulation path 30 by the exhaust / circulation pump 35 (circulation process).

[0031] In other words, the residual air after the depressurization process acts as a carrier gas due to its flow, and the leaked test component (H2) is diffused throughout the entire circulation path 30. Therefore, after the circulation flow of the test gas g is regulated by the circulation process, the concentration of the test component (H2) in the test gas g will be constant, provided that the leakage is constant. Furthermore, the test gas g can be flowed in the section from the second chamber 12 to the branch 31c of the return path 31 (the compression path 32 in the compression process described later). The flow velocity of the test gas g can be increased by increasing the capacity of the circulation pump 35. It is not necessary to increase the flow velocity or flow rate of the carrier gas in order to increase the flow velocity. By reducing the amount of residual air through depressurization, the concentration of the test component in the test gas g can be increased. In addition, since no carrier gas is introduced from an external source, the leaked test component (H2) is not diluted, and the amount that leaks can be deposited in the circulation path 30, thereby increasing its concentration.

[0032] After a predetermined time has elapsed for the circulation process, the on-off valve 34 is closed and the three-way valve 36 is set to the exhaust position 36b. This blocks the portion 30d between valves 34 and 36 in the return path 31, thereby stopping the circulation of the test gas g (circulation stop process). Furthermore, the on / off valve 25 of the test gas introduction passage 22 is closed, ending the process of introducing the test gas into the first chamber 11 (the internal space of the subject 9). Furthermore, the on-off valve 55 of the compressed gas supply passage 53 is closed and the on-off valve 57 is opened.

[0033] As a result, compressed gas consisting of clean air from the compressed gas tank 56 is introduced into the confluence section 31d downstream of the blocked section 30d. Instead of taking in air from around the device as compressed gas, clean air originating from the clean air introduction section 50a is stored in the compressed gas tank 56 and used as compressed gas. This prevents the background concentration of the test component (hydrogen) in the air around the device from being affected by repeated testing. Since the clean air originating from the clean air introduction section 50a is also supplied to the standby test component sensor 43, the concentration of the test component in the leak-free second chamber 12 and the test component sensor 43 can be made to the same level.

[0034] The compressed gas flows from the confluence section 31d to the downstream portion 31e of the return path 31, flows into the second chamber 12 from the return path end 31b, and then flows further through the second chamber 12 to the return path end 31a. The gas to be tested g is compressed by this compressed gas (compression process). Specifically, the gas to be tested g that was in the downstream portion 31e from the confluence section 31d to the return path end 31b of the return path 31, the second chamber 12, and the portion of the return path 31 from the return path end 31a to the branch section 31c (compression path 32) is compressed toward the sensor introduction path 49. By compressing the gas to be tested g from behind in the direction of flow while maintaining the flow direction of the gas to be tested g in the circulation process, mixing of the gas to be tested g and the compressed gas can be suppressed, and dilution of the concentration of the test component due to mixing can be prevented.

[0035] The compression process increases the pressure in the compression passage 32. When the pressure detected by the pressure gauge 33 in the compression passage 32 exceeds a predetermined value, the three-way valve 45 is energized (solenoid on) to shut off the air supply passage 42 and open the detection passage 41. As a result, the sensor introduction passage 49 communicates with the test component sensor 43, and the compressed test gas in the sensor introduction passage 49 is introduced to the test component sensor 43. In other words, the test gas can be compressed and pressurized to approximately atmospheric pressure before being supplied to the test component sensor 43, which is under approximately atmospheric pressure.

[0036] As a result, the concentration of the test component (H2) in the test gas is detected by the test component sensor 43 (detection step). In the aforementioned circulation step, the test component (H2) can be deposited without introducing a carrier gas from the outside, and the concentration of the test component in the test gas can be made uniform, thereby significantly increasing the detection sensitivity and improving the reliability of the detection. By creating a flow in the test gas g during the circulation process and further increasing the capacity of the circulation pump 35 to increase the flow velocity of the test gas g, the test gas can be rapidly introduced to the test component sensor during the detection process. There is no need to increase the flow velocity or flow rate of the carrier gas to achieve this speed, and there is no concern about dilution of the hydrogen concentration. This allows for a reduction in test time without compromising detection sensitivity. Based on the detection results, it is possible to determine whether there is a leak from the sample 9 and to determine whether the sample 9 is good or bad.

[0037] After passing through the test component sensor 43, the test gas is drawn into the exhaust pump 47 and exhausted (exhaust process). The detection process can be performed before the test gas is passed through the exhaust vacuum pump 47. Alternatively, the detection process can be performed without passing the test gas through the vacuum pump used to introduce it to the test component sensor 43. Therefore, the detection results are not affected by the absorption of test components by the sealing oil of the vacuum pump or by the pulsation of the vacuum pump. This increases the reliability of the leak test.

[0038] After the detection process, the three-way valve 45 is demagnetized (solenoid off) to shut off the detection path 41, and the air supply path 42 is opened to supply clean air to the inspection component sensor 43. Furthermore, by opening and closing the on-off valves 3V to 5V of paths 3 to 5, the inside of the subject 9 (first chamber 11) is cleaned (cleaning step), and the on-off valve 34 of the return path 31 is opened to clean the second chamber 12 (cleaning step). After that, the subject 9 is removed from the chamber 10 (removal step).

[0039] Next, other embodiments of the present invention will be described. In the following embodiments, components that overlap with those described above are denoted by the same reference numerals in the drawings and their descriptions are omitted. <Second Embodiment (Figures 3-4)> As shown in Figure 3, in the leak test apparatus 1B according to the second embodiment, a bypass passage 60 is added to the leak test apparatus 1 of the first embodiment. The upstream end of the bypass passage 60 branches off from the connecting passage 39. The downstream end of the bypass passage 60 merges with the portion of the exhaust passage 46 upstream of the exhaust pump 47B (on the side of the outlet port 41b of the leak test apparatus 1B). A normally closed electromagnetic valve 61 is provided in the bypass passage 60. Preferably, in the second embodiment, a rotary pump capable of producing a high vacuum is used as the exhaust pump 47B.

[0040] As shown in the chart in Figure 4, in the second embodiment, during the second chamber depressurization process, the on-off valve 61 on the bypass passage 60 is opened. This allows the gas in the second chamber 12 to be evacuated by the rotary pump 47B, thereby increasing the vacuum level in the second chamber 12. At the same time, the on-off valve 34 on the return passage 31 may also be opened. By doing so, the gas in the second chamber 12 can also be drawn in by the exhaust / circulation pump 35, increasing the depressurization rate of the second chamber 12 and shortening the second chamber depressurization process.

[0041] In the second embodiment, the second chamber 12 may be depressurized using only the rotary pump 47B. In this case, the pump 35 can be used exclusively as a pump for circulating the test gas g in the circulation process. In other words, the pump for the second chamber depressurization process and the pump for the circulation process can be separated.

[0042] <Third Embodiment (Figures 5-6)> As shown in Figure 5, in the leak test apparatus of the third embodiment, connection ports 15 and flow straightening sections 70 are provided on the upstream side wall 13 and the downstream side wall 14 of the chamber 10, which face each other along the circulation path 30. The connection ports 15 are located on one side (the lower side in Figure 5) of the outer circumference of each wall 13, 14. The return path end 31b of the return path 31 is connected to the connection port 15 of the upstream side wall 13. The forward path end 31a is connected to the connection port 15 of the downstream side wall 14. As shown in Figure 6, the cross-sectional shape of the outer circumference of the chamber 10 in the third embodiment is circular, but it is not limited to this and may be a polygon such as a square.

[0043] The rectifier section 70 includes a wall cavity 71 and a number of openings 72. The wall cavity 71 is connected to the connection port 15 and extends in the in-plane direction of the wall sections 13 and 14. Preferably, the flow path cross-sectional area of ​​the wall cavity 71 decreases as it moves toward the opposite side from the connection port 15 (upper side in Figure 5).

[0044] As shown in Figures 5 and 6, the numerous openings 72 are arranged in a dispersed manner in the in-plane direction of the wall portions 13 and 14. Each opening 72 is connected to the wall cavity 71 through a connecting portion 72c and opens to the chamber cavity 12 while expanding.

[0045] More specifically, the opening 72A, located in the inner portion of the outer periphery of the wall portions 13 and 14, has a rectangular shape when viewed from the chamber interior space 12 side. The opening 72A may also be a square pyramidal shape, and the opening 72A, which had a circular cross-section in the communication portion 72c, may expand while deforming into a rectangular cross-section as it approaches the chamber interior space 12. The openings 72E located on the outer periphery of the wall portions 13 and 14 are partially or entirely circular or oblate when viewed from the chamber interior space 12 side. The opening 72 may also be cone-shaped.

[0046] As shown in Figure 5, preferably, each wall portion 13, 14 includes a wall body 17 and a plate-shaped flow straightening member 73. The flow straightening member 73 is superimposed on the side of the wall body 17 facing the chamber interior space 12. An internal wall space 71 is defined between the wall body 17 and the flow straightening member 73. An opening 72 is formed in the flow straightening member 73.

[0047] According to the third embodiment, in the circulation process, the gas to be tested g is introduced from the return path end 31b of the return path 31 to the connection port 15 of the upstream side wall 13 into the wall cavity 71 of the wall 13, and flows along the wall cavity 71 so as to spread in the in-plane direction of the wall 13, and flows into the chamber cavity 12 while diffusing from each opening 72 of the wall 13. In other words, the gas to be tested g flows into the chamber cavity 12 from almost the entire surface of the wall 13.

[0048] The test gas g, which flows downstream (to the right in Figure 5) within the chamber space 12, is guided from almost the entire surface of the downstream side wall 14 into each opening 72 of the wall 14. From each opening 72, it is guided into the wall cavity 71 of the wall 14, collected at the connection port 15 of the wall 14, and then led out to the return path 31 from the forward path end 31a.

[0049] This allows the flow of the test gas g to be formed throughout the entire cross-sectional area of ​​the flow path within the chamber space 12, preventing the formation of areas where the test gas g accumulates within the chamber space 12. In particular, it prevents the accumulation of the test gas g in the corners of the chamber space 12. The flow of the compressed gas during the compression process is the same as that of the gas g under test, and the flow of the compressed gas can be formed throughout the entire cross-sectional area of ​​the flow path within the chamber space 12.

[0050] Therefore, according to the third embodiment, if there is leakage of the test component (H2) from the sample 9, it is possible to prevent the test component from accumulating in a specific location within the chamber space 12, and to ensure that the concentration of the test component in the test gas g is uniform. This makes it possible to stabilize the detection results. Furthermore, since it is possible to prevent the test component from remaining in a specific location within the second chamber 12 and becoming background after detection, when leak testing is performed on multiple samples 9 sequentially, it is possible to avoid the accumulation of background that affects the detection results. As a result, the reliability of the leak test can be improved.

[0051] By arranging multiple openings 72 in the in-plane direction of the walls 13 and 14, the rectifier section 70 can be made compact, preventing the wall thickness of the walls 13 and 14 from becoming excessively large. In addition, because the internal space of the openings 72 is small, the increase in the chamber volume can be suppressed, preventing a decrease in detection sensitivity.

[0052] If a single opening were to be constructed such that it tapers outwards from a small cross-sectional area connection port 15 toward the inner surface of the walls 13 and 14 facing the chamber space until its cross-sectional area is the same as the area of ​​the inner surface of the walls 13 and 14, the axial length of the single opening would need to be considerably large. This would not only lead to an increase in the size of the equipment, but the internal space of the single opening would be added to the chamber space, increasing the chamber volume and reducing the detection sensitivity.

[0053] <Fourth Embodiment (Figures 7-8)> As shown in Figure 7, the fourth embodiment of the present invention is a variation of the third embodiment (Figures 5-6), in which the chamber 10 is formed in a rectangular cross-sectional shape. The rectifier section 70 of the fourth embodiment includes an inner lining plate 74 and a plurality of opening members 75. The inner lining plate 74 is superimposed on the inner surface of the wall body 17 of each wall section 13, 14 that faces the chamber interior space.

[0054] As shown in Figures 7 and 8, the interior lining plate 74 has one header path 74a and multiple branch paths 74b. The header path 74a extends straight up and down in the center of the interior of the interior lining plate 74 in the width direction (left and right in Figure 8). A connection port 15 provided in the center of the wall body 17 communicates with the center of the header path 74a in the longitudinal direction.

[0055] The branch passages 74b are formed in a groove shape on the surface 74d of the lining plate 74 facing the chamber interior space, and extend in the width direction (left and right in Figure 8). The central part (one location) of the longitudinal direction of the branch passage 74b communicates with the header passage 74a so as to intersect it. Multiple branch passages 74b are arranged at intervals from each other in the direction of extension of the header passage 74a. The internal wall space 71 is formed by the header path 74a and the branch path 74b.

[0056] Multiple opening members 75 are provided on the side 74d of the lining plate 74 facing the chamber interior space. Each opening member 75 is formed in the shape of an isosceles triangle, for example, and extends in the width direction (left and right in Figure 8). The opening members 75 at both the top and bottom ends have a cross-sectional shape of a right triangle, which is half the shape of the isosceles triangle. The surface 75b of each opening member 75, which corresponds to the base of the isosceles or right triangle, is aligned with the side 74d of the lining plate 74 and joined by bolting or the like (not shown). Each opening member 75, except for those at the top and bottom ends, is positioned between two adjacent branches 74b on the lining plate 74.

[0057] An opening 72 is formed between two vertically adjacent opening members 75. In the fourth embodiment, the opening 72 is formed in the shape of a triangular groove that extends in the width direction (left and right in Figure 8) with a triangular cross-section that widens toward the chamber interior space 12. Multiple openings 72 are arranged side by side vertically.

[0058] In the two adjacent opening members 75 located vertically, a communication gap 75d is formed between the corners 75c created by the base-equivalent surface 75b and the inclined surface 75a. The communication gap 75d is slit-shaped and extends in the width direction (left and right in Figure 8). The branch path 74b and the opening 72 are in communication through this communication gap 75d. According to the fourth embodiment, the flow straightening section 70, which consists of a wall cavity 71 and an opening 72, can be easily manufactured.

[0059] The present invention is not limited to the embodiments described above, and various modifications can be made as long as they do not contradict the spirit of the invention. For example, the internal space of the subject 9 may constitute the second chamber 12, and the space inside the chamber may constitute the first chamber 11. A branching section may be provided in the chamber. A merging section may be provided in the chamber. In the third and fourth embodiments (Figures 5 to 8), only one of the upstream wall portion 13 and the downstream wall portion 14 may have the flow straightening portion 70. [Industrial applicability]

[0060] The present invention is applicable, for example, to leak testing techniques for determining the quality of industrial products such as electronic components and automotive parts. [Explanation of Symbols]

[0061] 1.1B Leakage Testing Apparatus 9 Subjects 10 chambers 11. The internal space of the subject (Room 1) 12. Chamber space (2nd chamber) 13 Upstream wall section 14 Downstream wall section 15 connection ports 17 Wall Unit 20. Inspection gas introduction method 21. Inspection gas sources 22 Inspection gas introduction path 23 Regulator 24 Pressure gauges 25 Solenoid valve 30 Circulatory pathways 30d A portion of the downstream side of the branching point in the circulation path 31 Round trip 31a Outbound end (end) 31b Return path end (end) 31c Branch 31d Confluence 32 Compression path 33 Pressure gauge 34 Electromagnetic valve 35. Exhaust / Circulation Pump (Circulation Pump) 36 Solenoid three-way valve 36a Opening position 36b Exhaust position 37 Pressure gauge 39 connecting routes 40. Leak detection unit (hydrogen leak detector) 41 detection path 41a Entrance Port 42 Air supply path 43. Sensor for inspecting components 47,47B Exhaust pump 49 Sensor introduction path 50 Clean air passage 50a Clean air inlet 50b Access to the air supply line 51 Regulator 52 Pressure gauge 53 Compressed gas supply line 54 Variable aperture 55 Electromagnetic valve 56 Compressed gas tank 57 Electromagnetic valve 59 Compression path Route 60 Bypass 61 Electromagnetic valve 70 Rectifier 71 Wall cavity 72 Opening 73 Rectifying member 74 Interior trim panel 74a Header path 74b branch road 75 Opening material 75a Slope 75c Corner 75d Communication gap g Test gas

Claims

1. A leak test method that involves testing a sample for leaks using a test gas containing the test component, The process involves introducing the test gas into the first chamber, which is one of two chambers consisting of the internal space of the subject housed in the chamber and the chamber space between the chamber and the subject. A step of reducing the pressure in the second chamber, A step of circulating the gas to be tested in the second chamber along a circulation path consisting of a return path with both ends connected to the second chamber and the depressurized second chamber, The process involves stopping the circulation and compressing the gas to be tested with compressed gas towards a sensor introduction path branched off from the circulation path, The process involves introducing the compressed gas to be tested through the sensor introduction path to a test component sensor under approximately atmospheric pressure or high pressure from the second chamber, and detecting the test component. A leak test method characterized by comprising the following features.

2. The leak test method according to claim 1, characterized in that, in the stopping and compression steps, a portion of the return path downstream of the branch to the sensor introduction path is blocked, and the compressed gas is supplied to the downstream side of the blocked portion of the return path.

3. A leak test device that performs a leak test on a sample using a test gas containing the test component, A chamber for containing the subject, A test gas introduction path connected to the first chamber, which is one of the two chambers consisting of the internal space of the subject and the chamber space between the chamber and the subject, A pressure reducing pump connected to the second chamber, A return path that connects both ends to the second chamber and forms a circulating path, A circulation pump that circulates the gas to be tested in the second chamber along the circulation path, A sensor introduction path branched off from the aforementioned circulation path, A compressed gas supply path supplies compressed gas to the circulation path so that the gas to be tested after circulation is compressed toward the sensor introduction path, A test component sensor connected to the aforementioned sensor introduction path and positioned under approximately atmospheric pressure or a pressure higher than the second chamber, A leak testing apparatus characterized by being equipped with the following features.

4. The leak test apparatus according to claim 3, characterized in that the return path is provided with, in order from the upstream side, a branching section to the sensor introduction path, the circulation pump, and the junction section with the compressed gas supply path.

5. The chamber has an upstream wall and a downstream wall along the circulation path, and at least one of these walls is A connection port to the end of the aforementioned return path, A wall space that is connected to the aforementioned connection port and extends in the in-plane direction of the wall portion 1, Multiple openings are connected to each other in the wall cavity and are arranged to be dispersed from one another in the in-plane direction of the wall, The leak test apparatus according to claim 3 or 4, wherein the opening is opened to the chamber space while expanding from the wall space.

Images