Functionality testing of leak detection devices for leak testing of test objects filled with liquid

Abstract

An improved leak test apparatus and method are provided for use in testing the functionality of a leak detection device for leak testing a test object filled with a liquid. [Solution] The test leak device of the present invention, which is used for functionality testing of a leak detection device that performs leak inspection on a test specimen 14 filled with a liquid 12 and having an internal pressure lower than atmospheric pressure, comprises a reservoir 102 having an outlet 106 and filled with a test liquid 104 having a vapor pressure of less than 500 mbar at room temperature, and a pump 100 configured to cooperate with the reservoir 102 to pump the test liquid 104 from the reservoir 102 so that it is discharged in a liquid state through the outlet 106 of the reservoir 102.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for testing the functionality of a leak detection device for leak testing a test object filled with a liquid. [Background technology]

[0002] It is known to perform leak testing on liquid-filled test specimens, such as batteries, to verify the seal of the specimen. Generally, such specimens do not have a gas available for use as a test gas within the specimen, making it neither possible nor desirable to actively fill the specimen with a different test gas. For example, this applies to batteries filled with an electrolyte, such as lithium-ion batteries, which are filled with an electrolyte containing dimethyl carbonate as an essential component.

[0003] The leak detection of such a test body is based on the principle that a detector detects the portion of the liquid inside the test body that has escaped through a leak point. In the leak test, the test body is introduced into a vacuum chamber. The portion of the liquid that has leaked from the test body is continuously pumped out of the vacuum chamber by the vacuum system of a vacuum pump and supplied to an appropriate sensor.

[0004] In the refrigeration / air conditioning industry, it is common to perform leak testing of test objects filled with liquid refrigerant, such as heat exchangers. Such test objects are characterized by the liquid refrigerant being contained within the test object under overpressure, thereby maintaining the refrigerant in a liquid state. To test such test objects filled with liquid refrigerant, a sniffer probe is guided along the portion of the test object to be tested for leaks, aspirating vaporized refrigerant that has leaked into the atmosphere from the leak location and feeding the vaporized refrigerant into a gas detector. The sniffer probe draws air from outside the test object, capturing the leaked gas. The gas is selectively detected by a corresponding sensor, allowing it to be distinguished from the aspirated air components. Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a test specimen filled with liquid and having an internal pressure lower than the atmospheric pressure outside the test specimen (for example, when the internal pressure is in the range of 50 to 500 mbar), the leaking gas does not leak out even when a leak occurs, so the suction leak detection method cannot be applied. For example, in the case of a battery filled with an electrolyte with a low vapor pressure, which creates negative pressure, air will enter the test specimen from the outside when a leak occurs. This leakage cannot be detected with a sniffer probe.

[0006] Conventional calibration equipment and test leak devices cannot be used to verify the functionality of the above-mentioned types of leak detection devices. This is because conventional test leaks are based on the principle of storing a test liquid in a reservoir and then pumping it out of the reservoir through a capillary or membrane. In contrast, this leak detection device uses test liquids with low vapor pressures of less than 500 mbar at room temperature. For example, the vapor pressure of ethyl acetate solvent is 103 mbar at 20°C. Such test liquids cannot be delivered in sufficient quantities to the detection system through capillaries or membranes due to pressure differences.

[0007] Against this background, it is an object of the present invention to provide an improved test leak device and method for use in testing the functionality of leak detection devices for leak testing of test objects filled with liquid. [Means for solving the problem]

[0008] The test leak device according to the present invention is defined by the configuration of claim 1.

[0009] That is, a test liquid having a vapor pressure of less than 500 mbar at room temperature is filled in a reservoir. The reservoir has an outlet for the test liquid. A feature of the device according to the present invention is that a pump configured to pump the test liquid from the reservoir cooperates with the reservoir to discharge the test liquid in liquid form through the outlet of the reservoir. The pump allows a sufficient amount of liquid with a low vapor pressure to be pumped into the leak detection device per pumping operation.

[0010] The pump may be, for example, a micrometering pump configured to deliver the test liquid from the outlet at a rate of less than 100 μl, preferably less than 100 nl per delivery. The test leak device and / or the pump and / or the outlet may be configured to deliver the test liquid from the outlet as a spray mist. The pump may include a piezoelectric liquid metering device that measures the rate at which the pump delivers the liquid per delivery.

[0011] The test object may be, for example, a battery, etc. The liquid in the test object and / or the test liquid may be an electrolyte or an individual component in an electrolyte.

[0012] The method according to the present invention is defined by the features of claim 6. First, a test chamber of a leak detection device is set to a pressure lower than atmospheric pressure. A predetermined amount of test liquid having a vapor pressure of less than 500 mbar at room temperature is then pumped into the test chamber. This amount of test liquid is then transported to a detector of the leak detection device and detected by the detector. The test liquid may be supplied to the detector in the form of vaporized molecular particles. Typically, the test liquid is vaporized after being discharged from an outlet of the test leak device. Typically, the test liquid vaporizes at the outlet or outlet flow path of a leak channel forming the outlet of the reservoir.

[0013] Preferably, the pump is configured to deliver a predetermined volume of test liquid from the outlet with each pump stroke, e.g., less than 100 μl, preferably less than 100 nl, of test liquid from the outlet with each pump stroke. The test liquid may be in a diluted state.

[0014] The test liquid may be delivered from the outlet as an atomized mist, or may exist in a gaseous state outside the reservoir by vaporizing through the outlet after leaving the reservoir.

[0015] The pump may be disposed between the reservoir and an outlet of the test leak device and in fluid communication with both the reservoir and the outlet.

[0016] It is assumed that no carrier gas is supplied to the test chamber from an external source, such as a carrier gas source connected to the test chamber, or that no carrier gas is introduced from outside the test chamber. Specifically, therefore, no gas flow is guided along the surface of the test object. Rather, a portion of the test liquid or particles, along with residual gas components, is sucked out of the test chamber and supplied to the detector. No carrier gas is required.

[0017] The test chamber may be configured as a rigid test chamber having rigidly formed walls. Alternatively, the test chamber may be configured as a film chamber. A film chamber is characterized by at least one flexible wall region that adheres to the test object when evacuated, thereby reducing the volume of the film chamber. Furthermore, a film chamber, especially one whose entire wall is made of a flexible film, has the advantage that the wall adheres to the test object and supports it, which is particularly advantageous when the test object is flexible.

[0018] The detector comprises a sensor capable of selectively detecting a target portion or particle of the liquid and distinguishing it from other portions or gases. The portion of the discharged liquid can be supplied to the detector in a liquid state. In this regard, the detector must be capable of analyzing liquids and selectively detecting the liquid contained in the test body. The leaked liquid or the test liquid can be supplied to the detector in the form of, for example, a mist or aerosol.

[0019] Alternatively, the liquid may vaporize upon leaking from the leak location in the test specimen, and the leaked vaporized portion of the liquid may be supplied to the detector in a vaporized, i.e., gaseous, state. In this case, the detector must be configured as a gas detector capable of analyzing gases and selectively distinguishing the gaseous liquid within the test specimen from other gases. The key factor here is that the liquid contained in the test specimen does not change from a liquid state to a gaseous state until it exits the test specimen, i.e., until it reaches the outside of the test specimen or the opening or flow path of the leak. In other words, even if the liquid vaporizes upon leakage from the leak location, it remains in a liquid state within the test specimen, and therefore the gas present within the test specimen is not used as the test gas.

[0020] The detector of the portion of the liquid to be detected may be a gas detector, for example a mass spectrometer, a gas chromatograph, an infrared absorption detector, a detector having a chemical or semiconductor sensor, or the like.

[0021] Preferably, the gas flow transporting the portion of the liquid is not supplied to the detector until a predetermined pressure limit is reached in the test chamber or in the connecting line between the test chamber and a vacuum pump evacuating the test chamber, which may be in the range of 2 to 50 mbar, but is preferably less than 20 mbar.

[0022] A vacuum pump, preferably a membrane pump, may be connected via a valve to the test chamber and / or to the gas line connecting the test chamber to the vacuum pump. When the test chamber begins to be evacuated, the valve is closed. When the pressure limit is reached, the valve is opened, allowing a portion of the flow to reach the detector, while the remaining main gas flow continues to be sucked by the membrane pump. This differs from the common carrier gas method in that the accumulation of the liquid leaking from the leak point is carried out in particular in conjunction with a vacuum pump in the form of a membrane pump. When the pressure limit is reached, the portion of the liquid accumulated up to that point is supplied to the detector.

[0023] Advantageously, the specimen in the test chamber is purged with a purge gas to remove any part of the liquid adhering to the specimen before the functionality test is carried out, and preferably the specimen is purged with a purge gas before the actual leak check or functionality test, e.g., evacuation of the test chamber, is carried out.

[0024] It is envisaged that the portion of the test liquid may be stored in the test chamber or in the connecting line for a predetermined period of time before the test liquid is supplied to the detector for analysis.

[0025] Exemplary embodiments of the present invention will now be described in detail with reference to the drawings. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram of an exemplary embodiment of a leak detection device. [Figure 2] FIG. 1 is a block diagram of an exemplary embodiment of a test leak apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0027] In this exemplary embodiment, a test chamber 16 contains a specimen 14 filled with a liquid 12. The specimen 14 is a battery filled with an electrolyte. In this exemplary embodiment, the test chamber 16 is a generally rigid test chamber.

[0028] The test chamber 16 is provided with a vacuum connection 22. Connected to the vacuum connection 22 is a vacuum pump 24 that can be used to evacuate the test chamber 16. For this purpose, the vacuum pump 24 consists of at least one vacuum pump in the form of a membrane pump. The test chamber 16 and the vacuum pump 24 are gas-communicatingly connected to each other by a connecting line 26, via which the vacuum pump 24 can suck gas out of the test chamber 16.

[0029] A detector 28 is connected to a connection line 26 connecting the test chamber 16 and the vacuum pump 24 to analyze and detect a portion of the liquid 12. In exemplary embodiments, the detector 28 is a selective gas detector, such as a mass spectrometer, that uses a sensor to selectively detect molecular particles in the liquid 12 and distinguish them from other gases. The detector 28 is part of a mass spectrometer vacuum system 20. The mass spectrometer vacuum system 20 includes a forepump 19 and a high vacuum pump 18 that evacuate the mass spectrometer 28.

[0030] The detector 28 is gas-conductively connected to the connection line 26 by a gas-conducting detection line 21. The detection line 21 is provided with a restriction 38 that throttles the gas flow branched from the connection line 26, and a valve V2 that selectively closes the detection line 21. A pressure sensor 17 is gas-conductively connected to the connection line 26 to measure the pressure within the connection line 26.

[0031] A portion of the liquid 12 leaks from the leak point in the test specimen 14 and enters the test chamber 16. Because the liquid 12 may vaporize as it leaks from the test specimen 14, the leaked portion of the liquid 12 may be in a gaseous state.

[0032] The detector 28 operates as a mass spectrometer in the vacuum system 20, which has a pressure lower than that in the test chamber 16 and lower than that at the junction 40 between the connection line 26 and the detection line 21. The membrane pump 24 used to evacuate the test chamber 16 according to the present invention does not create a high vacuum within the test chamber 16. Rather, the membrane pump 24 creates a pressure in the range of a few millibars (mbar). The membrane pump 24 also pumps out residual gas components still remaining in the test chamber 16. When the pressure in the test chamber 16 reaches a pressure within the range of approximately 10 mbar, gas components desorb from the walls of the test chamber 16, and the membrane pump 24 also pumps out these gas components. These gas components, i.e., the residual gas components in the test chamber 16 and the gas components desorbed from the walls of the test chamber 16, absorb the portion of the liquid 12 that has entered the test chamber 16 through the leak in the test specimen 14. This portion of the liquid 12 is supplied to the detector 28.

[0033] After evacuation, the vacuum pressure inside the test chamber 16 is a few millibars (mbar). At this pressure, the diffusion of the vaporized portion of the liquid 12 that has escaped from the test piece 14 is still inactive. The transport of the vaporized portion of the liquid 12 to the detector 28 is facilitated by the gas components, without the use of a carrier gas or the supply of a carrier gas to the test chamber 16 from the outside.

[0034] The functionality of the leak detection device is tested using a test leak device, as shown in Figure 2. The test leak device may also be used to calibrate the leak detection device. The test leak device includes a reservoir 102 filled with a test liquid 104. In this exemplary embodiment, the test liquid is dimethyl carbonate solvent. A pump 100 pumps the test liquid 104 from the reservoir 102 to an outlet 106 and out of the outlet 106.

[0035] Pump 100 pumps test liquid 104 in liquid form out of outlet 106. Depending on the pressure conditions in test chamber 16, the test liquid exiting outlet 106 may form an aerosol in the form of a mist or may evaporate into a gaseous state. The portion of the test liquid thus exiting outlet 106 is transported to detector 28 for analysis. In this case, the measured detection signal is assigned to a known, predetermined amount of the test liquid in order to calibrate detector 28.

[0036] The portion of the test liquid 104 that is discharged from the outlet 106 is accumulated in the test chamber 16 or in the connecting line 26 before being passed through the detector. 28 1 between the connection point 40 and the membrane pump 24. When a sufficient vacuum pressure is reached in the test chamber 16, the valve can be closed to allow the discharged liquid to accumulate in the test chamber 16 or between the valve (not shown) and the test chamber 16 in the connecting line 26, after which detection can be performed. Detection can be performed by opening the valve V2. During accumulation, the valve V2 can be either closed or open. The present invention includes the following embodiments. [Aspect 1] A test leak device used for functionality testing of a leak detection device that performs a leak test on a test body (14) filled with a liquid (12) and having an internal pressure lower than atmospheric pressure, comprising: a reservoir (102) having an outlet (106) and filled with a test liquid (104) having a vapor pressure of less than 500 mbar at room temperature; a pump (100) associated with the reservoir (102), configured to pump the test liquid (104) from the reservoir (102) through the outlet (106) of the reservoir (102) so that the test liquid is discharged in a liquid state; 1. A test leak device comprising: [Aspect 2] 10. The test leak device according to claim 1, wherein the pump (100) is a micro-metering pump configured to deliver the test liquid (104) from the outlet (106) at a flow rate of less than 100 μl, preferably less than 100 nl, per delivery operation. Aspect 3 10. The test leak device according to claim 1 or 2, wherein the test leak device and / or the pump (100) and / or the outlet (106) are configured to deliver the test liquid (104) from the outlet (106) as a spray mist. Aspect 4 4. The test leak device according to any one of aspects 1 to 3, wherein the pump (100) is equipped with a piezoelectric liquid metering device that measures the flow rate of liquid delivered by the pump (100) for each delivery operation. Aspect 5 5. The test leak device according to any one of claims 1 to 4, wherein the test body (14) is a battery, and / or the liquid (12) is an electrolyte or a solvent, and / or the test liquid (104) is an electrolyte or a solvent. Aspect 6 A method for testing the functionality of a leak detection device for leak testing a test body (14) filled with a liquid (12) and having an internal pressure lower than atmospheric pressure, comprising: evacuating the test chamber (16) of the leak detection device to a pressure below atmospheric pressure; delivering a predetermined amount of test liquid (104) having a vapor pressure of less than 500 mbar at room temperature into the test chamber (16); delivering a volume of the test liquid (104) to a detector (28) of the leak detection device; detecting the transported amount of test liquid (104) with the detector (28); A method comprising: Aspect 7 A method according to aspect 6, characterized in that the test liquid (104) is delivered by a test leak device according to any one of aspects 1 to 5. Aspect 8 8. The method according to claim 6 or 7, wherein the test liquid (104) is delivered from the outlet (106) at a flow rate of less than 100 μl, preferably less than 100 nl, per delivery operation. Aspect 9 9. The method of any one of aspects 6 to 8, wherein the test liquid (104) is delivered from the outlet (106) as an atomized mist. Aspect 10 10. The method according to any one of claims 6 to 9, wherein the test liquid (104) is sucked out of the test chamber (16) together with residual gas components and / or gas components desorbed from the walls of the test chamber (16) and supplied to the detector (28) without a separate carrier gas being supplied to the test chamber (16) from outside. Aspect 11 11. The method of any one of aspects 6 to 10, wherein the detector (28) is a gas detector, such as a mass spectrometer, a gas chromatograph, an infrared absorption detector, or a detector having a chemical or semiconductor sensor. Aspect 12 12. The method of any one of claims 6 to 11, wherein the detector (28) is operated in a vacuum system at a pressure lower than the pressure in the test chamber (16). Aspect 13 13. The method according to any one of claims 6 to 12, wherein the test liquid (104) is accumulated in the test chamber (16) or in the connecting line for a predetermined period of time before the test liquid (104) is detected by the detector (28). Aspect 14 14. The method of any one of claims 6 to 13, wherein the test liquid (104) is not supplied to the detector (28) until a predetermined pressure limit is reached in the test chamber (16), preferably the pressure limit being in the range of 2 to 100 mbar or less than 20 mbar.

Claims

1. 1. A test leak device used for functionality testing of a leak detection device, in which a test body (14) filled with a liquid (12) and having an internal pressure lower than atmospheric pressure is leak-tested in a test chamber (16), comprising: a reservoir (102) having an outlet (106) and filled with a test liquid (104) having a vapor pressure of less than 500 mbar at room temperature; a pump (100) cooperating with the reservoir (102), configured to pump the test liquid (104) from the reservoir (102) so that the test liquid is discharged in a liquid state through the outlet (106) of the reservoir (102); 1. A test leak device comprising:

2. 2. The test leak device according to claim 1, characterized in that the pump (100) is a micro-metering pump configured to deliver the test liquid (104) from the outlet (106) at a flow rate of less than 100 μl, preferably less than 100 nl per delivery operation.

3. 3. A test leak device according to claim 1 or 2, characterized in that the test leak device and / or the pump (100) and / or the outlet (106) are configured to deliver the test liquid (104) from the outlet (106) as an atomized mist.

4. 4. A test leak device according to claim 1, wherein the pump (100) is equipped with a piezoelectric liquid metering device that measures the flow rate of the liquid delivered by the pump (100) for each delivery operation.

5. 5. A test leak device according to any one of claims 1 to 4, characterized in that the test body (14) is a battery and / or the liquid (12) is an electrolyte or a solvent and / or the test liquid (104) is an electrolyte or a solvent.

6. A method for testing the functionality of a leak detection device for leak testing a test body (14) filled with a liquid (12) and having an internal pressure lower than atmospheric pressure, comprising: evacuating the test chamber (16) of the leak detection device to a pressure below atmospheric pressure; a predetermined amount of test liquid (104) having a vapor pressure of less than 500 mbar at room temperature is pumped into the test chamber (16) by a pump (100) cooperating with a reservoir (102); delivering a volume of the test liquid (104) to a detector (28) of the leak detection device; detecting the transported amount of test liquid (104) with the detector (28); A method comprising:

7. 7. The method according to claim 6, characterized in that the test liquid (104) is delivered by a test leak device according to any one of claims 1 to 5.

8. 8. The method according to claim 7, characterized in that a flow rate of the test liquid (104) of less than 100 μl, preferably less than 100 nl is delivered from the outlet (106) per delivery operation.

9. 9. The method of claim 7 or 8, wherein the test liquid (104) is delivered from the outlet (106) as an atomized mist.

10. 10. The method according to claim 6, wherein the test liquid (104) is sucked out of the test chamber (16) together with residual gas components and / or gas components desorbed from the walls of the test chamber (16) and supplied to the detector (28) without a separate carrier gas being supplied to the test chamber (16) from the outside.

11. 11. The method according to any one of claims 6 to 10, characterized in that the detector (28) is a gas detector, such as a mass spectrometer, a gas chromatograph, an infrared absorption detector, a detector with a chemical or semiconductor sensor, or the like.

12. 12. The method according to any one of claims 6 to 11, characterized in that the detector (28) is operated in a vacuum system at a pressure lower than the pressure in the test chamber (16).

13. 13. The method according to claim 6, wherein the test liquid (104) is detected by the detector (28) after the test liquid (104) has been accumulated for a predetermined period in the test chamber (16) or in a connecting line connecting the test chamber (16) to a vacuum pump (24) that evacuates the test chamber (16).

14. 14. The method according to any one of claims 6 to 13, characterized in that the supply of the test liquid (104) to the detector (28) does not occur until a predetermined pressure limit is reached in the test chamber (16), preferably the pressure limit being in the range of 2 to 100 mbar or less than 20 mbar.

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