Leak detection equipment and seal inspection method

Abstract

When the internal volume of the component under test is small compared to the internal volume of the test chamber, or when trying to increase the sensitivity of the test, a considerably long detection time is required. 【Solution means】A first pressure sensor (6) for measuring the pressure within the internal volume of the test chamber (2) surrounding the object (3), a test line (4), a preliminary discharge line (5) fluidly connected to the test chamber (2) and including a first pump device (7), a first preliminary discharge valve (8) and a second preliminary discharge valve (9), and a buffer volume (V T ) are provided, and a control unit (19) configured to control the preliminary discharge valves (8, 9) and the test valve (12) based on the measured values of the first pressure sensor (6) and the second pressure sensor (11) is provided. When no large-scale leak is detected, the pressure within the test chamber (2) is reduced until the pressure measured by the second pressure sensor (11) reaches below a low pressure threshold, and the concentration of the tracer gas is measured using a leak detector (13).

Description

Technical Field

[0001] The present invention relates to leak detection equipment for inspecting the seal of at least one object having an internal cavity containing a tracer gas with a volume of 50 cm 3 or less, wherein the at least one object is placed in a test chamber having an internal volume that is at least five times the volume of the internal cavity of the object. The present invention also relates to a method for inspecting the seal of the at least one object at very high speed.

Background Art

[0002] It is known to perform leak tests using tracer gases such as helium to verify the tightness of re-sealable hollow objects, in particular to inspect the closure seals of these objects. According to the prior art, to verify the tightness of a hollow object, a tracer gas is introduced into the cavity of the object, and then the object is closed and placed in a sealed test chamber under vacuum. When an appropriate vacuum is achieved in the test chamber, a leak detector is used to check whether a tracer gas is present in the internal atmosphere of the test chamber.

Summary of the Invention

Problems to be Solved by the Invention

[0003] One problem encountered in the prior art is that in some cases, the volume of the test chamber is too large compared to the volume of the object to be tested, for example, to accommodate objects that are bulky due to their complex shape.

[0004] In fact, when the internal volume of the part to be tested is small compared to the internal volume of the test chamber that houses this part (a minimum ratio of 1 / 5), it is necessary to place the relatively large volume surrounding the object to be tested under vacuum, which takes a considerable amount of time. In the case of large leaks from the object (usually, the leak size is 0.2 mm or more), and in the case of an object with a small internal cavity volume (usually, the internal volume of the object to be tested is 50 cm 3If it is less than this), due to an overly long step to reduce the pressure, there is a time when the cavity of the object becomes completely empty, and there is a possibility that all of the tracer gas will disappear before the analyzer is connected to the laboratory. Therefore, it is impossible to detect large leaks through a tracer gas using this method. Another problem regarding detecting small leaks from such objects in a larger volume test chamber is that the time it takes for the pressure to drop in these large volumes is too long and not compatible with the production rate.

[0005] Another method that does not use a tracer gas can also detect large leaks from the object under test. This method involves placing a pre-evacuated buffer volume in communication with the test chamber at atmospheric pressure for a few seconds (about 4 seconds). This equalizes the pressure between the test chamber and the buffer volume, and the test chamber is isolated. By monitoring the change in pressure measurement in this test chamber, large leaks (size 0.2 mm or more) can be detected over a test period of about 2 seconds. However, a total period of about 6 seconds is too long. Furthermore, this detection time becomes even longer when trying to increase the sensitivity of the test, that is, when trying to detect smaller leaks, and a detection time of up to 4 to 6 seconds is required for leaks on the order of 1 / 10 mm. Beyond this value, detection becomes difficult due to background noise from gas leakage through the walls of the test chamber in this method, and small leaks from the object under test cannot be detected. To obtain an accurate estimate of the leak, it is necessary to wait until the gas leakage is complete, that is, up to 15 seconds at most.

[0006] One of the objectives of the present invention is to propose a method for inspecting the seal of at least one object having an internal cavity volume of 50 cm that contains a tracer gas and is smaller (at least 5 times smaller) than the volume of the test chamber 3 in order to at least partially overcome these drawbacks. This method can detect both small and large leaks and can do so with a very short detection time.

Means for Solving the Problems

[0007] The present invention relates to leak detection equipment for inspecting the seal of at least one object having an internal cavity containing a tracer gas with a volume of 50 cm 3 or less, and the leak detection equipment includes: a test chamber having an internal volume that is at least five times or more the volume of the internal cavity of the at least one object and intended to accommodate the at least one object; a first pressure sensor configured to measure the pressure within the internal volume of the test chamber surrounding at least one of the objects; a test line fluidly connected to the test chamber and including a test valve and a leak detector configured to measure the concentration of the tracer gas within the internal volume of the test chamber; a preliminary discharge line fluidly connected to the test chamber, the preliminary discharge line including a first pump device, first and second preliminary discharge valves, and a buffer volume interposed between the first and second preliminary discharge valves; the preliminary discharge valve is interposed between the test chamber and the second preliminary discharge valve, and the second preliminary discharge valve is interposed between the first preliminary discharge valve and the first pump device; the ratio of the internal volume of the test chamber to the buffer volume is less than 1 and greater than 0.2, and the preliminary discharge line includes a second pressure sensor configured to measure the pressure within the buffer volume; the leak detection equipment further includes a control unit configured to control the preliminary discharge valve and the test valve based on the measurement values of the first and second pressure sensors; in a first stage of a preliminary discharge step, in this stage, the test chamber communicates with the buffer volume, and a large-scale leak test of the test chamber is performed by monitoring an increase in the pressure measurement value of the test chamber by the first pressure sensor; by the control unit; a first stage of a preliminary discharge step, in which the test chamber communicates with the buffer volume, and a large-scale leak test of the test chamber is performed by monitoring an increase in the pressure measurement value of the test chamber by the first pressure sensor; If the large leak is not detected, a second step is performed following the first step. In this second step, the pressure in the test chamber is reduced until the pressure measured by the second pressure sensor reaches a low pressure threshold, for example, 100 Pa or less, and the low pressure test step can be executed by measuring the concentration of the tracer gas using the leak detector. The duration of the preliminary evacuation step is 2 seconds or less.

[0008] Therefore, in a single test, it is possible to detect a tracer gas and detect a small leak, and also to detect a large leak from the object to be inspected by monitoring the change in pressure. Therefore, the seal of the object to be inspected can be inspected over the entire range of leaks within one and the same detection cycle.

[0009] According to the present invention, the preliminary evacuation time is shortened compared to the large leak detection method according to the prior art. By saving this time, it is possible to prevent all of the tracer gas contained in the internal cavity of the object from being emptied, and a small leak from the object can be detected in a more sensitive low pressure test step. By saving this time, it is also possible to improve the productivity. This seal inspection method can also be fully or partially automated.

[0010] This embodiment has the advantage that it requires only a limited number of valves, which means that it is not necessary to increase the volume of the test chamber, and thus it is not necessary to increase the time required to reduce the pressure in the first and second steps of the preliminary evacuation step. Thereby, the cost of the equipment can also be limited.

[0011] Another advantage is that the seal inspection method becomes reproducible from one object to be inspected to another because the test chamber is preliminarily evacuated using a buffer volume, that is, a volume isolated from any pumping device, and thus the seal inspection method is relatively independent of the pumping capacity of the pumping device.

[0012] The pressure in the test chamber can be reduced from atmospheric pressure to an equilibrium pressure, for example, 40000 Pa (400 mbar) or less, in less than 1 second, for example, 500 milliseconds, according to the ratio of the internal volume of the test chamber to the buffer volume. Also, the duration of the second stage can be set to 1 second or less. Therefore, the duration of the preliminary evacuation combining the two steps is less than 2 seconds because the duration of the first stage is shortened on the one hand and the duration of the second stage is shortened on the other hand.

[0013] The leak detection facility may further include one or more of the following features alone or in combination. The volume of the test chamber is, for example, 40 cm 3 or more.

[0014] The first pressure sensor may be configured to measure pressures from 20000 Pa to 60000 Pa, for example, with an accuracy of + / - 50 Pa and in particular with a response (or stabilization) time of less than 50 milliseconds. The first pressure sensor is, for example, a piezoelectric sensor. The second pressure sensor is configured to measure pressures from 1 Pa to 1000 Pa, for example, with an accuracy of + / - 1 Pa.

[0015] The present invention also relates to a method for inspecting the seal of at least one object having an internal cavity containing a tracer gas with a volume of 50 cm 3 or less, The method for inspecting the seal includes a loading step of arranging at least one object in a test chamber having an internal volume of at least 5 times or more the volume of the internal cavity of the at least one object. The method for inspecting the seal includes a preliminary evacuation step prior to the low-pressure test step. The preliminary evacuation time of this preliminary evacuation step is 2 seconds or less, and is characterized by including the following steps. A first stage of communicating the test chamber with a buffer volume interposed between the first and second preliminary evacuation valves by closing the second preliminary evacuation valve to communicate the buffer volume with the first pumping device and opening the first preliminary evacuation valve. The ratio of the internal volume of the laboratory to the buffer volume is less than 1 and greater than 0.2. The first preliminary discharge valve is interposed between the laboratory and the second preliminary discharge valve. The second preliminary discharge valve is interposed between the first preliminary discharge valve and the first pump device. The large-scale leak test of the laboratory is carried out by monitoring the increase in the measured pressure value inside the laboratory by the first pressure sensor. If no large-scale leak is detected, a second stage is carried out following the first stage. The second preliminary discharge valve is opened to lower the pressure inside the laboratory, and the first pump device is used to lower the pressure inside the laboratory through the buffer volume. The low-pressure test step can be carried out by measuring the concentration of the tracer gas with a leak detector until the pressure measured by the second pressure sensor reaches a low-pressure threshold value, for example, 100 Pa or less.

[0016] Before the first stage, the buffer volume may be placed under vacuum by the first pump device, preferably at a pressure of less than 1000 Pa, for example, 200 Pa or less, for example, 100 Pa.

[0017] Also, before performing the large-scale leak test itself, it is possible to confirm the presence of an object inside the laboratory by comparing the increase in the measured pressure value inside the laboratory with a control threshold value in advance.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0019] The following description of specific embodiments of the present invention (but not limited thereto), read together with the accompanying drawings, will reveal further advantages and features. In the drawings, the same elements are given the same reference numerals. The following embodiments are examples. The description refers to one or more embodiments, but this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to one embodiment. The individual features of different embodiments can also be combined or exchanged to provide other embodiments.

[0020] FIG. 1 shows an example of leak detection equipment 1 for inspecting the seal of at least one object 3 having an internal cavity containing a tracer gas hereinafter. The object 3 to be inspected is, for example, resealable. 3 Helium or hydrogen is generally used as a tracer gas because the size of its atoms or molecules is small and it can easily pass through smaller leaks than other gases. Helium or hydrogen is generally used as a tracer gas because the size of its atoms or molecules is small and it can easily pass through smaller leaks than other gases.

[0021] The leak detection equipment 1 includes a test chamber 2 for accommodating at least one object 3 for checking the leak of the seal, a test line 4, a preliminary discharge line 5, and a first pressure sensor 6 configured to measure the pressure in the internal volume of the test chamber 2 surrounding at least one object 3 to be tested. The test line 4 and the preliminary discharge line 5 are fluid-connected to the test chamber 2.

[0022] The preliminary discharge line 5 includes a first pump device 7, first and second preliminary discharge valves 8, 9, and a buffer volume V disposed between the first preliminary discharge valve 8 and the second preliminary discharge valve 9. T The preliminary discharge valves 8, 9 are arranged in series on a first pipe 10 of the preliminary discharge line 5 intervening between the test chamber 2 and the first pump device 7.

[0023] More specifically, the first preliminary discharge valve 8 intervenes between the test chamber 2 and the second preliminary discharge valve 9. The second preliminary discharge valve 9 intervenes between the first preliminary discharge valve 8 and the first pump device 7. The buffer volume V T is the internal volume of the first pipe 10 intervening between the first and second preliminary discharge valves 8, 9. The volume between the second preliminary discharge valve 9 and the first pump device 7 is, as shown below, the buffer volume V T and then the buffer volume VT And in order to shorten the time required to place the laboratory 2 under vacuum, it is preferably minimized.

[0024] The first pumping device 7 includes a rough vacuum pump such as a vane pump, for example. The preliminary discharge line 5 also includes a second pressure sensor 11 configured to measure the pressure within the buffer volume V T The second pressure sensor 11 is, for example, a standard vacuum sensor with a response time of about 200 milliseconds. For example, it is configured to measure pressures from 1 Pa to 1000 Pa. This second pressure sensor 11 is, for example, a standard vacuum sensor with a response time of about 200 milliseconds. For example, it is configured to measure pressures from 1 Pa to 1000 Pa.

[0025] On the other hand, the first pressure sensor 6 is an accurate and fast sensor, and in particular, it is configured to measure pressures from 200 mbar (20000 Pa) to 600 mbar (60000 Pa) with a response time of less than 50 milliseconds, for example, about 1 millisecond. The first pressure sensor 6 is, for example, a piezoelectric sensor.

[0026] The test line 4 includes a test valve 12 and a leak detector 13 configured to measure the concentration of tracer gas within the internal volume of the test chamber 2. The leak detector 13 includes second pumping devices 14, 15 and a gas analyzer 16 for measuring the concentration of at least one gas species used as a tracer gas. The second pumping devices 14, 15 include, for example, a high vacuum pump 14 such as a turbo molecular pump and a rough vacuum pump 15 connected in series thereto. The high vacuum pump 14 is arranged upstream of the rough vacuum pump 15 in the direction of the gas flow. The rough vacuum pump 15 is, for example, a vane pump or a small dry rough vacuum pump.

[0027] The gas analyzer 16 is connected, for example, to the suction port of the high vacuum pump 14. Accordingly, the measurement cell of the gas analyzer 16 is placed under a low pressure of about 10 -4 mbar. The gas analyzer 16 includes, for example, a mass spectrometer. The test valve 12 is fluidly connected to the second pump devices 14, 15. That is, it is fluidly connected to, for example, the intermediate compression step of the high vacuum pump 14 and / or the suction port of the high vacuum pump 14 according to the required leakage level. The test line 4 and the preliminary discharge line 5 are arranged in parallel, for example.

[0028] The vent line 17 is also fluidly connected to the test chamber 2 in parallel with, for example, the other two lines 4, 5, whereby air can enter the test chamber 2 and return to atmospheric pressure. The vent line 17 includes, for example, an air inlet valve 18 that fluidly connects the test chamber 2 to the external atmosphere or neutral gas.

[0029] The atmosphere inside the test chamber 2 may communicate with the test line 4 or the preliminary discharge line 5, and in this case, it may also communicate with the vent line 17. The test chamber 2 has an internal volume that is at least five times or more the internal cavity volume of at least one object 3. This volume is required to be minimized as much as possible and to be able to accommodate at least one object 3 to be tested.

[0030] This internal volume of the test chamber 2 is obtained by subtracting the external volume of at least one object 3 (and thus all objects 3 if there are multiple objects 3) from the volume of the test chamber, and then adding the volume of the piping between the test chamber 2 and the first preliminary discharge valve 8, the test valve 12, and the air inlet valve 18 (if applicable) (the valves are closed). This internal volume is configured to measure the pressure of the test chamber 2, for example, by the first pressure sensor 6 being fluidly connected. Or the first pressure sensor 6 is connected between the outlet of the test chamber 2, the first preliminary discharge valve 8, the test valve 12, and the air inlet valve 18 and is configured to measure the pressure there.

[0031] The volume of the test chamber 2 is, for example, 40 cm 3 or more. The ratio of the internal volume of the test chamber 2 to the buffer volume V T is less than 1. The internal volume of test chamber 2 and the buffer volume V T The ratio to this is greater than 0.2. Due to these volume ratios, the pressure inside test chamber 2 can be reduced from atmospheric pressure to the equilibrium pressure, for example, 40000 Pa (400 mbar) or less, in less than 1 second, for example, 500 milliseconds.

[0032] The preliminary discharge valves 8, 9, the test valve 12, and the air inlet valve 18 may be solenoid valves such as electromagnetic valves, or may be air valves. These valves should have a fast opening and closing time (time < 50 ms) and high conductance.

[0033] These preliminary discharge valves 8, 9, the test valve 12, and the air inlet valve 18, if applicable, are controlled by the control unit 19 of the leak detection facility 1 such as a computer or a controller according to the measured values of the first and second pressure sensors 6, 11, and as described with reference to FIGS. 1 and 2, a very fast method 100 for inspecting the seal of at least one object 3 can be executed periodically and automatically.

[0034] The first pump device 7, the second pump devices 14, 15, and the gas analysis device 16 are operable and are considered to operate without interruption. At the start of the cycle, the second preliminary discharge valve 9 is open and all other valves are closed.

[0035] Therefore, the buffer volume V T is placed under vacuum by the first pump device 7, preferably at a pressure of less than 1000 Pa (or 10 mbar), for example, 200 Pa (or 2 mbar) or less, for example, 100 Pa (or 1 mbar). This pressure is controlled by the second pressure sensor 11. Thereby, the pressure inside the buffer volume V T is reliably controlled, and the expected balance of pressure between the test chamber 2 and the buffer volume V near the equilibrium pressure sensed by the first pressure sensor 6 for the large-scale leak test is ensured, and it is guaranteed that this equilibrium pressure is reached within the required short time. T

[0036] During the loading step 101, at least one object 3 containing a tracer gas is placed in a test chamber 2 that is at least five times the volume of the internal cavity of this object 3. The pressure in the test chamber 2 is the atmospheric pressure outside the test chamber 2, i.e., the atmospheric pressure. The test chamber 2 is then sealed.

[0037] Next, during the first stage 102a of the preliminary evacuation step 102 following the loading step 101, the test chamber 2 communicates with the buffer volume V of the preliminary evacuation line 5. T For this purpose, the second preliminary evacuation valve 9 that connects the buffer volume V to the first pumping device 7 is closed, and the first preliminary evacuation valve 8 is opened. For this, the second preliminary evacuation valve 9 that connects the buffer volume V to the first pumping device 7 is closed, and the first preliminary evacuation valve 8 is opened. T For this purpose, the second preliminary evacuation valve 9 that connects the buffer volume V to the first pumping device 7 is closed, and the first preliminary evacuation valve 8 is opened.

[0038] Next, the internal volume of the test chamber 2 communicates with the buffer volume V. This buffer volume V at a low atmospheric pressure enables a rapid expansion of the gas in the test chamber 2. This pressure equalizes within these communicating volumes and can be measured by the first pressure sensor 6. T Next, the internal volume of the test chamber 2 communicates with the buffer volume V. This buffer volume V at a low atmospheric pressure enables a rapid expansion of the gas in the test chamber 2. This pressure equalizes within these communicating volumes and can be measured by the first pressure sensor 6. T Next, the internal volume of the test chamber 2 communicates with the buffer volume V. This buffer volume V at a low atmospheric pressure enables a rapid expansion of the gas in the test chamber 2. This pressure equalizes within these communicating volumes and can be measured by the first pressure sensor 6. The pressure can be reduced from atmospheric pressure to an equilibrium pressure, for example, 40,000 Pa (400 mbar) or less, by the volume ratio between the internal volume of the test chamber 2 containing at least one object 3 and the buffer volume V. T The pressure can be reduced from atmospheric pressure to an equilibrium pressure, for example, 40,000 Pa (400 mbar) or less, by the volume ratio between the internal volume of the test chamber 2 containing at least one object 3 and the buffer volume V. Thus, if there is a defect in at least one object 3, the tracer gas leaks from the leak opening and spreads into the test chamber 2 and the buffer volume V without being discharged by the first pumping device 7. T Thus, if there is a defect in at least one object 3, the tracer gas leaks from the leak opening and spreads into the test chamber 2 and the buffer volume V without being discharged by the first pumping device 7. The duration of this first sequence is 500 milliseconds or less.

[0039] Next, a large-scale leak test of the test chamber 2 is performed by monitoring the rise in the measured pressure value in the test chamber 2 using the first pressure sensor 6. For this purpose, the buffer volume V TMeasure the time-dependent increase in the pressure measurement value in the laboratory 2 that is in communication with, compare it with the threshold value, and check whether this increase is as expected or whether the pressure measurement value is increasing faster than expected. A rapid increase in pressure means that the tracer gas is leaking from the leak in the object 3 in the laboratory 2, and thus there is a large leak in the object 3.

[0040] This measurement is performed by a first pressure sensor 6 configured to detect small changes in pressure with a very short response time within the equilibrium pressure range. The advantage of performing the large leak test while the first preliminary discharge valve 8 is open is that time can be saved because when this valve is closed, the volume moves and then it is necessary to wait for at least 200 milliseconds for a new pressure equilibrium before performing the measurement.

[0041] Also, before performing the large leak test itself, it is also possible to confirm the presence of the object 3 in the laboratory 2 by comparing the increase in the pressure measurement value in the laboratory 2 with the control threshold value in advance. If this pressure increase is lower than the control threshold value, the object can be placed in the laboratory and the large leak test can be performed. The value of the control threshold can also be used to determine that the object has the expected dimensions. This preliminary discharge step 102 can detect large leaks from at least one object 3, particularly large leaks with a hole size of 0.2 mm or more.

[0042] If a large leak is detected, the object 3 is identified as a defective product and the cycle of the seal inspection method 100 is completed.

[0043] If no large leak is detected, the seal inspection method 100 includes a second step 102b following the first step 102a of the preliminary discharge step 102. In this step, the pressure in the laboratory 2 is reduced to a low pressure threshold value of, for example, 1 mbar (100 Pa) or less. This pressure is controlled by a second pressure sensor 11 configured to measure this low pressure.

[0044] For this purpose, the second preliminary discharge valve 9 is opened, and the pressure in the laboratory 2 is reduced by the first pump device 7 through the buffer volume V T Thereby. The two preliminary discharge valves 8 and 9 are opened. Due to the volume ratio between the internal volume of the laboratory 2 containing at least one object 3 and the buffer volume V T the duration of this second stage 102b is 1 second or less.

[0045] Therefore, the preliminary discharge period, that is, the combined period of the two steps, is 2 seconds or less due to the shortening of the period of the first stage 102a on the one hand and the shortening of the period of the second stage 102b on the other hand. The shortening of these periods is made possible particularly by the volume ratio between the internal volume of the laboratory 2 containing at least one object 3 and the buffer volume V T and.

[0046] By saving time in this preliminary discharge step 102, it is possible to prevent all the tracer gas contained in the internal cavity of the object 3 from being emptied. Therefore, a small leak from the object 3 can be detected in the more sensitive low-pressure test step 103. This time saving also makes it possible to improve the production rate.

[0047] When the pressure drops below the low-pressure threshold, for example, below 100 Pa, for example, between 10 -2 mbar and 10 -3 mbar, the pressure in the laboratory 2 becomes low enough for the test valve 12 to open and the test line 4 to communicate with the laboratory 2 (low-pressure test step 103). Therefore, the first preliminary discharge valve 8 is closed, the test valve 12 is opened, the laboratory 2 is switched to the test line 4, and the laboratory 2 is in fluid communication with the leak detector 13.

[0048] At the same time, the first preliminary discharge valve 8 is closed, and the pressure in the buffer volume V T is reduced by the first pump device 7 through the preliminary discharge valve 9 that remains open. Therefore, this is performed as a background task during the low-pressure test. The buffer volume VT Since it is placed under vacuum as a background task, the duration of the background task can be extended to reduce outgassing and improve the sensitivity of the large leak test.

[0049] In this low-pressure test step 103, the test chamber 2 communicates with the test line 4 to determine the concentration of the tracer gas, and the leak detector 13 detects leaks from the at least one object 3. A part of the gas sucked by the second pumping devices 14, 15 passes through the high-vacuum pump 14. The gas analyzer 16 detects whether the gas sample contains a tracer gas indicating a leak. The tracer gas present in the test chamber 2 as a result of the defective object 3 is detected by the leak detector 13.

[0050] The low-pressure test step 103 enables the detection of small leaks from at least one object 3, especially with a hole size of less than 0.5 mm. Therefore, the leak detection facility 1 can detect leaks with a hole size between 0.5 mm and 0.2 mm in both the large leak test with rough vacuum and the low-pressure test with high vacuum. The overlapping range of this leak size is relatively large.

[0051] Next, in the step 104 of returning to atmospheric pressure, the test valve 12 is closed and the air inlet valve 18 is opened. As a result, the pressure in the test chamber 2 rises to atmospheric pressure. Next, the test chamber 2 is opened to remove the tested object 3 (unload step 105), and at least one new test object 3 can be loaded (load step 101).

[0052] In this way, in a single test, it is possible to detect a tracer gas to detect small leaks and also detect large leaks from the object 3 by monitoring the pressure change. Therefore, the seal of the object can be inspected over the entire range of leaks within one and the same detection cycle.

[0053] Furthermore, the method 100 for inspecting the seal can be fully or partially automated. In particular, all valves that can connect the test chamber 2 to the preliminary discharge line 5, the test line 4, or the vent line 17 can be automatically controlled.

[0054] According to an embodiment of the present invention, there is an advantage that the number of required valves is limited. This means that there is no need to increase the volume of the test chamber 2, and thus there is no need to increase the time required to reduce the pressure in the first and second stages 102a, 102b of the preliminary discharge step 102. Thereby, the cost of the leak detection facility 1 can also be limited.

[0055] Another advantage of the present invention is that the method 100 for inspecting the seal becomes reproducible from the inspection of one object 3 to the inspection of another object by using a buffer volume V T , that is, a volume isolated from any pumping device, to preliminarily discharge the test chamber 2, because the method is relatively independent of the pumping capacity of the pumping device.

Explanation of reference numerals

[0056] 1 Leak detection facility 2 Test chamber 3 Object 4 Test line 5 Preliminary discharge line 6 First pressure sensor 7 First pumping device 8 First preliminary discharge valve 9 Second preliminary discharge valve 10 First pipe 11 Second pressure sensor 12 Test valve 13 Leak detector 14 Second pumping device 15 Second pumping device 16 Gas analyzer 17 Vent line 18 Air inlet valve 19 Control unit V T Buffer volume

Claims

1. The volume of the internal cavity containing the tracer gas is 50 cm ３ Leak detection equipment (1) for inspecting the seal of at least one of the following objects (3), The leak detection facility (1) is a test chamber (2) having an internal volume that is at least five times or more the volume of the internal cavity of the at least one object (3), and this test chamber (2) is intended to accommodate the at least one object (3), a first pressure sensor (6) configured to measure the pressure within the internal volume of the test chamber (2) surrounding the at least one object (3), a test line (4) fluidly connected to the test chamber (2) and including a test valve (12) and a leak detector (13) configured to measure the concentration of the tracer gas within the internal volume of the test chamber (2), a preliminary discharge line (5) fluidly connected to the test chamber (2) and including a first pumping device (7), a first preliminary discharge valve (8), and a second preliminary discharge valve (9), A buffer volume (V Ｔ ) is provided between the first preliminary discharge valve (8) and the second preliminary discharge valve (9), the first preliminary discharge valve (8) is interposed between the test chamber (2) and the second preliminary discharge valve (9), and the second preliminary discharge valve (9) is interposed between the first preliminary discharge valve (8) and the first pumping device (7), The ratio of the internal volume of the laboratory (2) to the buffer volume (V Ｔ ) is less than 1 and greater than 0.2, The preliminary discharge line is configured to measure the pressure within the buffer volume (V Ｔ ), and includes a second pressure sensor (11). Further, a control unit (19) configured to control the preliminary discharge valves (8, 9) and the test valve (12) based on the measured values of the first pressure sensor (6) and the second pressure sensor (11), the control unit (19) During the first stage (102a) of the preliminary discharge step (102), the laboratory (2) communicates with the buffer volume (V Ｔ ) and performs a large-scale leak test of the laboratory (2) by monitoring the increase in the pressure measurement value in the laboratory (2) with the first pressure sensor (6). if no large leak is detected, in a second stage (102b) following the first stage (102a), the pressure within the test chamber (2) is reduced until the pressure measured by the second pressure sensor (11) reaches below a low pressure threshold value, and by using the leak detector (13) to measure the concentration of the tracer gas, it has the function of performing a low pressure test step (103), The leak detection facility, wherein the duration of the preliminary discharge step (102) is 2 seconds or less.

2. The volume of the laboratory (2) is 40 cm ３ The leak detection facility according to claim 1, characterized in that it is 40 cm or more.

3. The leak detection facility according to claim 1, wherein the first pressure sensor (6) is configured to measure a pressure of 20,000 Pa to 60,000 Pa with a response time of less than 50 milliseconds.

4. The leak detection facility according to claim 1, wherein the first pressure sensor (6) is a piezoelectric sensor.

5. The leak detection facility according to claim 1, wherein the second pressure sensor (11) is configured to measure a pressure of 1 Pa to 1000 Pa.

6. A method (100) for inspecting the seal of at least one object (3) having an internal cavity with a volume of 50 cm3 or less and containing a tracer gas, The method (100) for inspecting the seal includes a loading step (101) of arranging the at least one object (3) in a test chamber (2) having an internal volume that is at least five times or more the volume of the internal cavity of the at least one object (3), The method (100) for inspecting the seal includes a preliminary evacuation step (102) prior to a low-pressure test step (103), The duration of the preliminary evacuation in the preliminary evacuation step (102) is 2 seconds or less, The preliminary evacuation step is, Close the second preliminary discharge valve (9) and communicate the buffer volume (V Ｔ ) with the first pump device (7), and open the first preliminary discharge valve (8), whereby the test chamber (2) is connected to the buffer volume (V Ｔ ) intervening between the first and second preliminary discharge valves 8, 9). Execute the first stage of communication, and in the first stage, The ratio of the internal volume of the laboratory (2) to the buffer volume (V Ｔ ) is less than 1 and greater than 0.2, and the first preliminary discharge valve (8) is interposed between the laboratory (2) and the second preliminary discharge valve (9), The second preliminary evacuation valve (9) is interposed between the first preliminary evacuation valve (8) and the first pumping device (7), A large-scale leak test of the test chamber (2) is performed by monitoring the increase in the measured pressure value in the test chamber (2) by a first pressure sensor (6), If the large leak is not detected, a second step (102b) is executed following the first step (102a), the second preliminary discharge valve (9) is opened, and the pressure in the test chamber (2) that has passed through the buffer volume (V Ｔ ) is reduced by the first pump device (7) until the pressure measured by the second pressure sensor (11) reaches a low pressure threshold value, and the concentration of the tracer gas is measured by the leak detector (13) so that the low pressure test step (103) can be executed. A method for inspecting the seal of an object (3), characterized in that.

7. Before the first stage (102a), the buffer volume (V Ｔ ) is placed under a vacuum of a pressure of less than 1000 Pa by the first pump device (7), the method for inspecting a seal according to claim 6, characterized in that.

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