FUNCTIONALLY TESTING A LEAK DETECTION DEVICE FOR CHECKING THE SEALING TIGHTNESS OF AN INSPECTION OBJECT FILLED WITH A LIQUID

Abstract

A test leak device for functional testing of a leak detection device for the leak test of a test specimen (14) filled with a liquid (12) having an internal pressure that is lower than atmospheric pressure, comprising a reservoir (102) filled with a test liquid (104), wherein the test liquid (104) has a vapor pressure of less than 500 mbar at room temperature, and the reservoir (102) comprises an outlet (106), and a pump (100) cooperating with the reservoir (102) and configured to convey the test liquid (104) from the reservoir (102) in such a way that the test liquid (104) escapes from the pump (100) through the outlet (106) in liquid form from the reservoir (102).

Claims

1.-14. (canceled)

15. A test leak device for functional testing of a leak detection device for the leak test of a test specimen filled with a liquid having an internal pressure that is lower than atmospheric pressure, comprising a reservoir filled with a test liquid, wherein the test liquid has a vapor pressure of less than 500 mbar at room temperature, and the reservoir comprises an outlet, and a pump cooperating with the reservoir and configured to convey the test liquid from the reservoir in such a way that the test liquid escapes from the pump through the outlet in liquid form from the reservoir.

16. The test leak device according to claim 15, wherein the pump is a micro-metering pump configured to deliver a flow rate of less than 100 ?l and preferably less than 100 nl of the test liquid from the outlet per conveying operation.

17. The test leak device according to claim 15, wherein the test leak device, the pump and/or the outlet are configured to convey the test liquid from the outlet as spray mist.

18. The test leak device according to claim 15, wherein the pump comprises a piezo liquid metering device for metering the flow rate to be delivered by the pump per conveying operation.

19. The test leak device according to claim 15, wherein the test specimen is a battery, the liquid is an electrolyte or solvent, and/or the test liquid is an electrolyte or solvent.

20. A method for functional testing of a leak detection device for the leak test of a test specimen filled with a liquid having an internal pressure that is lower than atmospheric pressure, comprising the steps of evacuating a test chamber of the leak detection device to a pressure lower than atmospheric pressure, delivering a predetermined amount of a test liquid, which has a vapor pressure of less than 500 mbar at room temperature, into the test chamber, transporting the delivered amount of test liquid to a detector of the leak detection device, and detecting the transported amount of test liquid by means of the detector.

21. The method according to claim 20, wherein the test liquid is delivered by means of a test leak device according to claim 15.

22. The method according to claim 20, wherein a flow rate of less than 100 ?l and preferably less than 100 nl of the test liquid is conveyed from the outlet per conveying operation.

23. The method according to claim 20, wherein the test liquid is conveyed from the outlet as spray mist.

24. The method according to claim 20, wherein the test liquid is drawn from the test chamber together with residual gas components and/or together with gas components desorbing from a wall of the test chamber and is supplied to the detector without a separate carrier gas being supplied to the test chamber from the outside.

25. The method according to claim 20, wherein the detector is a gas detector, such as a mass spectrometer, a gas chromatograph, an infrared absorption detector, or a detector with chemical or semiconductor sensors.

26. The method according to claim 20, wherein the detector is operated in a vacuum system with a lower pressure than the pressure within the test chamber.

27. The method according to claim 20, wherein the test liquid in the test chamber or in the connecting line is accumulated during a period of time before the test liquid is detected by means of the detector.

28. The method according to claim 20, wherein the test liquid is not supplied to the detector until a predetermined pressure limit value is reached in the test chamber, wherein the pressure limit value is preferably in the range between 2-100 mbar or is less than 20 mbar.

Description

[0025] In the following, an exemplary embodiment of the invention is explained in more detail with reference to the Figures. In the Figures:

[0026] FIG. 1 is a block diagram of an exemplary embodiment of the leak detection device, and

[0027] FIG. 2 is a block diagram of an exemplary embodiment of the test leak device.

[0028] In the exemplary embodiment, a test specimen 14 filled with a liquid 12 is contained in a test chamber 16. Test specimen 14 is a battery filled with a liquid electrolyte. In the present exemplary embodiment, test chamber 16 is a conventional rigid test chamber.

[0029] Test chamber 16 is provided with a vacuum connection 22 to which a vacuum pump 24 is connected which can be used to evacuate test chamber 16. For this purpose, vacuum pump 24 comprises at least one vacuum pump in the form of a membrane pump. Test chamber 16 and vacuum pump 24 are connected to each other in a gas-conducting manner by a connecting line 26 so that vacuum pump 24 can draw gas from test chamber 16 via connecting line 26.

[0030] A detector 28 for analyzing and detecting parts of liquid 12 is connected to connecting line 26 which connects vacuum pump 24 to test chamber 16. In both exemplary embodiments, detector 28 is a selective gas detector, for example in the form of a mass spectrometer, whose sensor selectively detects molecular particles of liquid 12 and can distinguish them from other gases. Detector 28 is part of a mass spectrometric vacuum system 20, which includes a pre-vacuum pump 19 and a high vacuum pump 18 for evacuating mass spectrometer 28.

[0031] Detector 28 is connected to connecting line 26 in a gas-conducting manner via a gas-conducting detection line 21. Detection line 21 is provided with a throttle 38 for throttling the gas flow diverted from connecting line 26, and with a valve V2 for selectively closing detection line 21. To measure the pressure within connecting line 26, the latter is connected to a pressure sensor 17 in a gas-conducting manner.

[0032] Parts of liquid 12 escape from a leak in test specimen 14 and enter into test chamber 16. As liquid 12 escapes from test specimen 14, it may evaporate so that the escaped parts of liquid 12 may be in gaseous form.

[0033] Detector 28 is operated as a mass spectrometer in vacuum system 20 at a pressure less than the pressure within test chamber 16 and less than the pressure at connecting point 40 between connecting line 26 and detection line 21. However, in membrane pump 24 used according to the invention to evacuate test chamber 16, no high vacuum is generated within test chamber 16. Rather, membrane pump 24 generates a pressure in the range of a few millibars. Membrane pump 24 draws any residual gas components still present from test chamber 16. In addition, when a pressure in the range of about 10 mbar is reached within test chamber 16, gas components desorb from the walls of the test chamber, which are also drawn by membrane pump 24. Said gas components, i.e. residual gas components from test chamber 16 and gas components desorbing from its walls, absorb parts of liquid 12 that enter into test chamber 16 through a leak from test specimen 14. Said parts of liquid 12 are supplied to detector 28.

[0034] The vacuum pressure inside test chamber 16 after evacuation is a few millibars. The diffusion of the parts of liquid 12 that have escaped from test specimen 14 and evaporated is still inert at this pressure. The transportation of the escaped parts of liquid 12 to detector 28 is accelerated with the gas components without using a carrier gas and supplying it to test chamber 16 from the outside.

[0035] The functionality of the leak detection device is tested with the test leak device illustrated in FIG. 2. Here, a calibration of the leak detection device can also be performed with the aid of the test leak device. The test leak device comprises a reservoir 102 filled with a test liquid 104. In the present exemplary embodiment, the test liquid is the solvent dimethyl carbonate. A pump 100 pumps test liquid 104 from reservoir 102 to outlet 106 and out of outlet 106.

[0036] Pump 100 conveys test liquid 104 in liquid form out of outlet 106. Depending on the pressure conditions in test chamber 16, it is conceivable that the test liquid escaping from outlet 106 forms an aerosol in the form of a spray mist or evaporates and changes to the gaseous phase. The parts of the test liquid that escaped from outlet 106 in this way are transported to detector 28 and analyzed thereby. In doing so, the measured detection signal is assigned to the known predetermined quantity of the test liquid, in the sense of calibrating detector 28.

[0037] It is conceivable that the parts of the liquid that escaped from outlet 106 are accumulated within test chamber 16 or within connecting line 26 before the escaped parts of test liquid 104 are supplied to detector 20. To this end, it is conceivable that a valve not shown in FIG. 1 is provided between connecting point 40 and membrane pump 24, which valve is closed when sufficient vacuum pressure is reached within test chamber 16 to cause an accumulation of the escaped liquid parts within test chamber 16 or in connecting line 26 between test chamber 16 and the valve not shown before detection occurs. Valve V2 can be opened for detection. During the accumulation phase, valve V2 can be closed or open.