Device for checking the tightness of electrochemical cells

Abstract

The invention relates to a device (1) for checking the tightness of electrochemical cells (2), in particular with regard to H2 tightness. The device has a chamber (3) for accommodating and checking at least one electrochemical cell (2). For the purpose of the check, the chamber (3) is subjected to a vacuum. A unit (6) for gas supply is provided, which supplies an electrochemical cell (2) to be checked with compressed air, as a result of which the interior of the electrochemical cell (2) is pressurized. This is made possible particularly advantageously in that the pressure difference between the interior of the cell (2) having the excess pressure and the chamber (3) having the vacuum is particularly high and is additionally varied periodically. As a result, there is a particular incentive for a periodically varying gas transfer between the interior of the cell (2) and the chamber (3) under vacuum, which allows for the tightness to be checked particularly advantageously and meaningfully. The pressure sensor (7) allows for a periodic pressure increase in the chamber (3) to be detected and to be analyzed by means of the control unit (8), and for meaningful information regarding insufficient tightness to be obtained, without interference by non-periodic interfering effects, and made available to the user. The device according to the invention can detect very minor leaks, which for example lead to leakage rates in the range of 10-4 mbar per liter of the volume and per second, and as a result can obtain very meaningful information regarding the required gas tightness of the electrochemical cells.

Description

[0001]3f)1,›MMJ. U PCT / DE2024 / 000036 MAFU Robotics GmbH Straub P822003 / PCT / 1 10.05.2024 Device for leak testing of electrochemical cells TECHNICAL FIELD The invention relates to a device for leak testing of electrochemical cells, in particular with regard to H2 leak tightness. PRIOR ART It is known that the leak tightness of housings can be tested by subjecting them and their internal volume to a test pressure and then checking whether this pressure inside the housing drops or not. This type of leak test proves to be very complex and requires a device that is specifically adapted to the housing to be tested. Furthermore, the information regarding leak tightness proves to be of little significance. Such a test device is known from US patent US 9,857,264 B2, which uses helium as the inspection gas, the escape of which is detected by means of so-called MENS.This device proves to be very costly and complex. US patent application US 2011 / 0174060 A1 discloses a system and method for testing the leak tightness of containers, which are used for transporting pharmaceuticals or medical substances or articles. 4 r_.nr) _ 3n , ,rlc2onl riatÄiSt Ar%lnPCT / DE2024 / 000036 are provided. For this purpose, the containers are placed in a vacuum chamber, and the degree of pressure change in the vacuum chamber is used as a measure of the density of the housing. This system is not very suitable for leak testing complex objects, especially those that exhibit even lower leak rates than these containers for the transport of pharmaceuticals or medical substances or objects, or those objects that are particularly susceptible to leaks of hydrogen or noble gases. Korean patent KR 101198857 B1 discloses a device for leak testing batteries, wherein the batteries are filled with liquid electrolytes. To suck the electrolytes out of the battery, the battery is placed in a vacuum chamber, and the vacuum vaporizes the liquid electrolytes and thereby sucks them out of the battery if it is not leak-tight.The gaseous electrolytes are then detected using a semiconductor sensor, and a measure of the leak is derived from this. This device proves to be very complex and unsuitable for complex objects, particularly those that exhibit even lower leak rates than these liquid-filled batteries, or objects that are particularly susceptible to leaks from hydrogen or noble gases. A device for testing the leak tightness of an electrolyte battery is known from Chinese utility model CN ​​207268665U. The battery to be tested is placed in a two-part housing with a base and a lid. The battery can be pressurized with liquid electrolyte via the lid, thereby creating a certain excess pressure. In contrast, the space 4J UJ J4_24J is described below.J14 PCT / DE2024 / 000036 in the sealed housing around the inserted battery to be tested, a vacuum is placed and checked to see whether electrolyte from the battery is leaking into the space around the battery, thereby reducing the vacuum in this space. If the vacuum difference exceeds a predetermined threshold, the battery is assessed as leaking. If the vacuum does not change, the battery is assessed as leak-tight. This arrangement is only suitable for batteries with a liquid electrolyte and unsuitable for electrochemical cells with gaseous reactants. DESCRIPTION OF THE INVENTION The object of the invention is to provide a device for leak testing of electrochemical cells that is improved over the prior art, particularly with regard to H2 leak-tightness. This device should be characterized by an efficient and meaningful leak-tightness test.This object is achieved according to the invention with a device for leak testing of electrochemical cells, which has the features specified in the claim. Advantageous embodiments of the invention are the subject of the dependent claims. The device according to the invention for leak testing of electrochemical cells, in particular with regard to hydrogen leakage, is provided with a chamber for accommodating and testing at least one electrochemical cell. The chamber is designed such that it is subjected to a negative pressure for the test.A gas supply unit is provided that can supply compressed air to an electrochemical cell to be tested, which is placed in the chamber and is to be tested. This makes it possible to pressurize the interior of the electrochemical cell, thus particularly advantageously supporting the possibility of identifying a pressure loss due to a leak in the introduced gas. This is made possible precisely because the pressure difference between the interior with the overpressure and the chamber with the negative pressure is particularly large, thus creating a special incentive for gas transfer between the interior and the chamber under negative pressure, which enables a particularly advantageous and meaningful leak test.This is made possible in particular by the provided pressure sensor, which is capable of detecting a periodic pressure increase in the chamber and analyzing it with the help of the control unit, thus obtaining meaningful information on the lack of tightness and making it available to the user. This is supported, among other things, by the fact that the chamber is equipped with a gas-tight housing and is thus designed to be so gas-tight that an increase in gas pressure in the chamber is caused by and attributable to one or more electrochemical cells under investigation introduced into the chamber.By providing simple compressed air as the test gas according to the invention and not providing special, cost-intensive test gases such as helium or other noble gases, it is possible to create a highly informative, yet cost-effective and correspondingly efficient device for assessing the tightness of electrochemical cells. The compressed air can contain one or more of the common atmospheric gases, in particular nitrogen, oxygen, and dry air. The device for testing the tightness of electrochemical cells is designed according to the invention such that the negative pressure in the chamber or the positive pressure in the electrochemical cell is selected such that the pressure difference between the negative pressure and the positive pressure varies periodically and the sensor for detecting a pressure change is suitable for detecting a periodicity in the pressure increase in the chamber.This recording and thus analysis is typically performed using a correlation function, which can be implemented, for example, as autocorrelation or cross-correlation. Here, the periodically varying pressure differences are correlated with the periodically varying pressure changes in the chamber and thus compared with each other. Fourier analysis can also be used to support the analysis, especially since the periodicity of the pressure difference is known. It has proven particularly advantageous to vary the pressure difference by varying only the overpressure in the electrochemical cell.This leads to even better detection of a periodicity in the sensor signal, which, on the one hand, makes it possible to identify and thus exclude disruptive influences from unwanted background signals in the sensor signal or in the negative pressure or pressure difference, and, on the other hand, enables a very reliable statement regarding the presence of leaks or the magnitude of the leaks. By providing such a structure and operating the device according to the invention, it becomes possible to detect even very small leaks, which, for example, lead to leak rates in the range of 10 mbar per liter of volume and lic_n=_011. • rtelnn1 u c cPCT / DE2024 / 000036 per second, thereby obtaining highly meaningful information on the required leak tightness of the electrochemical cells. This is particularly important for electrochemical cells that contain gaseous media rather than liquid electrolytes, particularly those containing hydrogen or noble gases such as helium or argon. Such electrochemical cells are particularly difficult to assess with regard to their leak tightness against helium or hydrogen, but this is made possible with the present inventive device for leak testing electrochemical cells, particularly with regard to H2 tightness. It has proven particularly useful to further develop the inventive device for leak testing such that the generated overpressure of the compressed air in the electrochemical cell is above bar.If the electrochemical cell has sufficient pressure resistance, the generated overpressure of the compressed air can be selected up to 200 bar. This is preferably achieved by designing the gas supply unit in such a way that the compressed air, at a pressure higher than the target pressure in the interior of the electrochemical cell to be tested, is fed gas-tight via connecting lines to the cell to be tested in the chamber. The interior is pressurized with compressed air until the desired overpressure is reached. This can be achieved either via a time control with knowledge of the relevant volume and the inflow velocity or with the aid of a pressure sensor that is suitable for measuring the gas pressure in the interior of the electrochemical cell to be tested for leaks and controlling the supply of compressed air accordingly. This significant overpressure in the interior OS -2024-38130801. —HauPtPmst -0023 PCT / DE2024 / 000036 In the cell, a pressure difference of several orders of magnitude, preferably in the range of to orders of magnitude, in mbar or hPa is generated between the chamber and the interior of the cell, thereby creating particularly meaningful devices for assessing leak tightness. Furthermore, it has proven particularly useful to further develop the device for leak testing such that the negative pressure in the chamber is, for example, in the range of or below 10 hPa. This is preferably achieved by equipping the chamber with a vacuum pump suitable for generating the desired negative pressure in the chamber and, if necessary, for specifically restoring it.Once the desired negative pressure in the chamber is reached, the vacuum pump is deactivated or the vacuum pump is separated from the chamber in a gas-tight manner so that the chamber maintains the desired negative pressure and even small increases in pressure in the chamber can be detected using the sensor for detecting an increase in pressure in the chamber. Due to this pronounced and selected strong negative pressure in the chamber and this significant overpressure in the interior of the cell, a pressure difference of several orders of magnitude in mbar or hPa is generated between the chamber and the interior of the electrochemical cell under test, thereby creating particularly meaningful devices for assessing leak tightness. In addition, it has proven particularly useful to further develop the leak testing device so that the chamber is designed to accommodate and test several electrochemical cells simultaneously.This preferred refinement improves the efficiency of the leak testing device. This refinement allows multiple cells to be tested in a shorter time using a single device, as the time required for exchanging the individual cells, including the associated emptying or filling of the chamber, and the subsequent evacuation after filling the chamber with a single cell can be reduced, thus accelerating the testing process for an individual cell. This is possible without significantly compromising the quality of the leak test.A particularly preferred development is a leak testing device in which the gas supply unit is designed to jointly pressurize the electrochemical cells to be tested, which are placed in the chamber, with compressed air, thereby placing the interior of the electrochemical cells under a common overpressure. This development of the leak testing device is characterized by a simple, efficient, and safe design with a single gas supply unit, which is jointly connected via a gas-tight supply line to the electrochemical cells to be tested, arranged in the chamber, so that they can be subjected to the overpressure according to the invention. This can occur simultaneously, sequentially, or partially sequentially.In addition, it has also proven useful to further develop the leak testing device so that the gas supply unit is designed to sequentially pressurize the electrochemical cells to be tested, thus enabling sequential testing. This is achieved in particular by supplying compressed air to each cell to be tested in the chamber via a common gas-tightness supply line. cmus(PCT / DE2024 / 000036) and this is done in such a way that a control valve is assigned to each cell to be tested, which, controlled by a control unit, sequentially releases only one electrochemical cell to be tested for filling with compressed air. After checking the tightness of this one released electrochemical cell, it is disconnected from the compressed air supply via the gas supply unit by closing the controllable control valve and releasing the next electrochemical cell to be tested using its assigned control valve and thus selectively pressurised with compressed air. This is repeated until all cells to be tested arranged in the chamber have been tested sequentially, i.e. one after the other, and their tightness can thus be checked individually.If an increase in pressure is detected in the negatively pressurized chamber using the assigned sensor, this enables clear assignment to the currently pressurized, released cell to be tested, which significantly improves the efficiency of the further developed device for leak testing. Preferably, the cells in the chamber that have already been tested are freed of the existing excess pressure, for example by venting them through a vent line. This is preferably done in a targeted manner via the control unit and a controllable valve arranged in the vent line, which temporarily releases the vent line for degassing. A particularly preferred development of the device for leak testing shows the possibility of arranging the sensor in the chamber to detect an increase in pressure.This design of the device makes it possible to ensure the tightness of the chamber in a particularly advantageous manner and thus to provide a particularly detailed and meaningful81c1LAMTMU7X. nrvcPCT / DE2024 / 000036 Information on the pressure increase in the chamber, which also improves the efficiency of the device. Thanks to this design, no supply lines need to be led through the chamber wall from the outside into the chamber interior and sealed accordingly, which has a beneficial effect on the tightness of the chamber. A preferred further development of the device for leak testing has proven to be that the sensor for detecting a pressure increase is arranged outside the chamber and is connected to the negatively pressurized interior of the chamber via a gas line. This further development makes it possible to read the sensor without great difficulty even during operation and to maintain or even replace it if necessary, without having to relieve the negative pressure in the chamber containing the electrochemical cells to be tested.This leads to improved handling of the improved device for leak testing of electrochemical cells, particularly with regard to tightness against noble gases or similar. According to a preferred development of the device for leak testing, an alarm unit is assigned to the sensor for detecting an increase in pressure, which alarm unit is suitable for emitting an alarm signal when an increase in pressure above a predetermined limit is detected and / or for storing and / or emitting information on the increase in pressure and / or on one or more cells being tested. The alarm signal is preferably implemented as a visual alarm signal, which can alternatively or additionally also be designed as an acoustic alarm signal. This ensures that as soon as an undesired increase in pressure is detected, this is used to identify a leak that is to be examined. 1= 3u nonl_u 45 _c _ l , u . mz . e , - " wx _—_nn7PCT / DE2024 / 000036 cell is interpreted and this leads to a clear assignment to a cell in the chamber. This allows the leak testing process to be carried out in a very targeted and efficient manner, especially in semi-automated or fully automated operations. In addition to or as an alternative to the alarm signal, it has also proven useful to save the information on the pressure increase or on the cell(s) currently being checked, thus documenting it and making it available for later review if necessary. This is particularly advantageous in fully automated, particularly sequential, testing of multiple cells, particularly multiple cells in one chamber. The data is preferably saved in an electronic memory, especially an electronic data memory that retains its data for an extended period even without an external power supply.From this, information on the tightness of individual cells examined can then be retrieved at a later time, and these cells can be classified as sufficiently tight or as unsuitable and thus not sufficiently tight, and sorted out accordingly. This leads to a very useful and efficient further development of the device according to the invention for testing tightness. It has proven particularly useful to design the device for testing tightness in such a way that the pressure increase is recorded over time and, if a pressure increase rate above a predetermined limit is detected, an alarm signal is emitted and / or information on the pressure increase and / or on one or more tested cells is stored and / or transmitted.The pressure increase rate can be used in addition to or as an alternative to purely considering the absolute pressure increase, with the pressure increase rate proving to be a more meaningful and thus more efficient measure for assessing the adequate tightness of electrochemical cells, particularly those with gaseous media. This refinement further improves the efficiency and informative value of the device. Using the pressure increase rate also makes it possible to reduce the time required for measuring the change in pressure in the chamber and thus for measuring a meaningful pressure increase, thereby increasing the efficiency of the device.It has proven particularly useful to further develop the leak testing device such that at least one, in particular all, of the electrochemical cells represent a fuel cell and / or a battery or an electrochemical sensor, which are supplied with gaseous media for the electrochemical reaction. This further development of this leak testing device proves particularly useful for these particularly sensitive types of electrochemical cells, especially when one or more receptacles for the introduction of this type of electrochemical cell are provided in the chamber, and these cells are specifically supplied with pressurized compressed air using the gas supply unit.For these special electrochemical cells, in particular fuel cells and electrochemical gas sensors as well as batteries with gaseous media, the importance of the tightness of the introduced gaseous media is particularly important with regard to hydrogen or 31. #lcuePCT / DE2024 / 000036 Noble gases are of particular importance, particularly for long-term functionality and, in some cases, even crucial for their efficiency. Furthermore, it has proven particularly advantageous to further develop the leak testing device so that the chamber has a lock for the introduction and / or removal of one or more cells to be tested. By providing such an additional lock to the chamber, it becomes possible to reduce the time required for changing cells to be tested and thus lessen the load on the device, particularly on the compressed air supply unit or on the sensors or holders for electrochemical cells. This reduces the vulnerability of the device and increases its efficiency.Furthermore, it has proven particularly advantageous to further develop the leak testing device such that the volume of the interior of the chamber of the device is slightly larger, in particular less than 20% larger, than the volume of the electrochemical cell or cells to be tested in the chamber. Preferably, in a further developed leak testing device, the volumes of the electrochemical cell or cells to be tested and the interior of the chamber of the device are adapted to one another in terms of their shape so that they correspond to one another and the volume of the interior of the chamber encloses the volume of the electrochemical cell or cells to be tested on all sides and protrudes slightly.As a result, the gas volume between the chamber housing and the electrochemical cell(s) to be tested arranged therein is small, which means that even small increases in volume due to leaks in the electrochemical cell(s) to be tested lead to a significant pressure increase in the interior space subjected to negative pressure, and this is thus very efficiently detected as a leak. This further increases the efficiency of the developed device. A particularly advantageous development of the device for leak testing of electrochemical cells is designed such that the negative pressure in the chamber or the positive pressure in the electrochemical cell is selected such that the pressure difference between negative pressure and positive pressure varies periodically, and the sensor for detecting a pressure change is suitable for detecting a periodicity in the pressure increase in the chamber.The variation in the pressure difference is selected to be sinusoidal or sawtooth-shaped and thus periodic. These variations in the pressure difference can be easily identified, and their effects on changes in the sensor signal can be recorded safely and reliably, making the statements regarding the tightness of the electrochemical cells particularly meaningful. Furthermore, it has proven particularly advantageous to further develop the device for leak testing such that the amplitude of the change in the pressure difference between negative pressure and positive pressure is selected so that it lies within a range of one or two orders of magnitude of the pressure difference, in particular within a factor of approximately the pressure difference. An exemplary embodiment of the invention has proven particularly advantageous in which the positive pressure is periodically varied within a range between approximately 2 bar and approximately 10 bar.Through this variation of the pressure difference, in particular through the exclusive variation of the overpressure -. nn-)PCT / DE2024 / 000036 in the electrochemical cell, on the one hand, a sufficiently clear change in the sensor signal and thus the detection of a periodicity in the sensor signal in the presence of an undesired leak is made possible. On the other hand, this is made possible without overly complex modifications to the device and thus with a simple structure of the device. The invention is explained below using preferred embodiments with reference to the figures. The invention is not limited to these preferred embodiments. Figure 1 shows a schematic sectional view of an exemplary device according to the invention for leak testing, and Figure 2 shows a schematic sectional view of another exemplary device for leak testing. In Fig.An exemplary development of the device according to the invention for leak testing of electrochemical cells is shown schematically. This device for leak testing is particularly suitable for testing the hydrogen tightness of the electrochemical cells to be tested. It is provided with a chamber for accommodating and testing at least one electrochemical cell. The chamber is designed such that it is subjected to a negative pressure for the test. With the aid of a gas supply unit, an electrochemical cell to be tested, which is introduced into the chamber, is pressurized with compressed air, thereby creating the possibility of pressurizing the interior of the electrochemical cell and thereby particularly advantageously supporting the possibility of identifying a pressure loss due to a leak for the introduced gas.This is made possible in a particularly advantageous way because the pressure difference between the interior of the cell with the overpressure and chamber 3 with the negative pressure is particularly large, thus creating a special incentive for gas transfer between the interior of the cell and the negatively pressurized chamber, which enables a particularly advantageous and meaningful leak test. The leak test is made possible in particular with the aid of the provided pressure sensor, which is suitable for detecting an increase in pressure in the chamber and thereby obtaining meaningful information about the lack of leaks in the cell. In addition to information on the pressure change, it also outputs an alarm signal to the user via the information unit, thus making it available to the user.The negative pressure in the chamber or the positive pressure in the electrochemical cell is selected such that the pressure difference between negative pressure and positive pressure varies periodically, and the sensor for detecting a pressure change is suitable for detecting a periodicity in the pressure increase in the chamber. This detection and thus analysis can be carried out, for example, using Fourier analysis, especially since the periodicity of the pressure difference is known. It has proven particularly advantageous to vary the pressure difference by varying only the positive pressure in the electrochemical cell. This ir_nr_eneA_'.›Q1'2noni_u PCT / DE2024 / 000036 leads to even better detection of a periodicity in the sensor signal, which, on the one hand, makes it possible to identify and thus exclude disruptive influences from unwanted background signals in the sensor signal or in the negative pressure or pressure difference, and, on the other hand, enables a very reliable statement regarding the presence of leaks or the magnitude of the leaks. This test is supported, among other things, by the fact that the chamber is equipped with a gas-tight housing and is thus designed to be so gas-tight that an increase in the gas pressure in the chamber is caused by and attributable to one or more electrochemical cells to be tested introduced into the chamber.The cell to be tested is positioned within the chamber's interior in such a way that a continuous, annular earring seal 10 ensures a tight connection between the cell and the housing of the chamber 3. This reduces the risk of a leak in the compressed air supply line 13 to the cell and thus of contamination of the chamber's interior, significantly reducing the risk of device malfunction due to a leak in the supply line 13 and thus an increase in pressure inside the chamber. By providing simple compressed air, which may contain one or more of the common atmospheric gases, in particular nitrogen, oxygen, and dry air, as the test gas, according to the invention, it is possible to create a highly informative, yet cost-effective, and correspondingly efficient device for assessing the tightness of electrochemical cells.7›‹21 hiaumxew,g PCT / DE2024 / 000036 It has proven particularly useful to design the device for leak testing according to the invention in such a way that the periodically varying, generated overpressure of the compressed air in the electrochemical cell is more than bar. This is preferably achieved in that the gas supply unit is designed in such a way that the compressed air, at a higher pressure than the target pressure in the interior of the electrochemical cell 2 to be tested, is fed in a gas-tight manner via connecting lines 13 to the cell to be tested in the chamber 3 and the interior of the cell is pressurized with compressed air until the desired overpressure is reached. This significant overpressure in the interior of the cell creates a pressure difference between the chamber and the interior of the cell of several, in particular 5 or orders of magnitude of mbar orhPa is generated and in this way particularly meaningful devices for assessing leaks have been created. In addition, it has proven particularly useful to design the device for leak testing in such a way that the negative pressure in chamber 3 is periodically varied in a range below 10 hPa. This is preferably achieved by providing the chamber with a vacuum pump which is suitable for generating the desired negative pressure in the chamber and, if necessary, for specifically restoring it. Once the desired negative pressure in the chamber has been reached, the vacuum pump is deactivated or the vacuum pump is separated from the chamber in a gas-tight manner such that the chamber maintains the desired negative pressure and even small increases in pressure in the chamber can be detected using the sensor for detecting a pressure increase in the chamber. Due to this pronounced and selected strong negative pressure in the chamber, the significant1=_n % r ,_enn,A_-4111nci.rel_mPCT / DE2024 / 000036 Overpressure in the interior of the cell 2, in particular a pressure difference between the chamber and the interior of the electrochemical cell to be examined of several, in particular of up to, orders of magnitude in mbar or hPa, is generated, thereby creating particularly meaningful devices for assessing leak tightness. It has proven useful for the sensor to detect an increase in pressure to be arranged outside the chamber 3 and to be connected via a gas line to the interior 5 of the chamber which is under negative pressure. This further development makes it possible to read out the sensor without great difficulty even during operation, and to maintain or even replace it if necessary, without the negative pressure in the chamber containing the electrochemical cells to be examined having to be relieved.This leads to an improvement in the handling of the further developed device for leak testing of electrochemical cells, particularly with regard to their tightness against noble gases or the like. According to a preferred embodiment of the device for leak testing, an alarm unit is assigned to the sensor for detecting a periodic pressure increase due to the periodically varying pressure difference between the negative pressure in the chamber and the positive pressure in the cell, which alarm unit is suitable for emitting an alarm signal upon detection of a variation in the pressure increase above a predetermined threshold and / or for storing and / or transmitting information on the pressure increase and / or on one or more tested cells. The alarm signal is preferably designed as an optical alarm signal and as an acoustic alarm signal.This ensures that as soon as an undesirable periodic pressure increase caused by a leak is detected, this is interpreted as the identification of a leaky cell to be examined, leading to a clear assignment to a cell in the chamber. It has also proven useful to store information about the specific, particularly periodic, pressure increase or the cell(s) currently being checked along with the alarm signal, thus documenting it and making it available for later review if necessary. This is particularly advantageous for fully automated, particularly sequential, testing of multiple cells, especially multiple cells in a chamber.The leak testing device is designed in such a way that the pressure increase due to the periodically varying pressure difference between the negative pressure in the chamber and the positive pressure in the cell is recorded over time. If a particularly periodic pressure increase rate above a predetermined limit is detected, an alarm signal is issued and / or information on the pressure increase and / or on one or more tested cells is stored and / or transmitted. The pressure increase rate can be used in addition to or as an alternative to purely considering the absolute pressure increase and / or to change the periodicity between the varying pressure difference between the negative pressure in the chamber and the positive pressure in the cell and the variation in the pressure increase.The rate of pressure increase, or rather the observation of the change in periodicity, has proven to be a more meaningful and thus more efficient measure for assessing the adequate tightness of electrochemical cells, particularly those containing gaseous media. This refinement further improves the efficiency and informative value of the device. The leak testing device is suitable for leak testing various electrochemical cells, particularly fuel cells and / or batteries or electrochemical sensors, which are primarily exposed to gaseous media for the electrochemical reaction. The leak testing device is controlled by a control unit.The control unit is connected via control lines 11 to controllable valves 12 in the supply lines 13 for supplying compressed air to the cell to be tested in the chamber, as well as to the sensor of the alarm unit and display unit and the gas supply unit. Control signals, as well as information or data that are necessary or useful for control by the control unit, are transmitted via these control lines 11. Figure 1 schematically shows an exemplary, alternative embodiment of a leak testing device according to the invention. In the following, only the essential and functional differences from the figure are explained with regard to the figure. Otherwise, the structure of the leak testing device according to the figure corresponds to the structure of the leak testing device according to Figure 1. The exemplary device shows several electrochemical cells that are to be tested for leaks.The three electrochemical cells are each connected via a supply line 13 with an integrated, controllable valve 12 with ei- lr_. / r il_Te.A 2 ')nOnl 0038PCT / DE2024 / 000036 a common supply line 13 to the compressed air gas supply unit. This common supply line 13 ensures that the compressed air supply is very efficient and effective for several cells to be tested, especially simultaneously. This significantly reduces the time required to test the multiple cells and thus increases the efficiency of the leak testing device. The controllable valves 12 are connected to the control unit via a common control line 11 so that they can be opened or closed simultaneously, but also sequentially, i.e., individually and one after the other.This makes it possible for one cell to be tested to be selectively pressurized with compressed air at a time and its leak tightness checked, followed by the next, until all three cells to be tested have been tested step by step. The valves 12 are selectively controlled so that only one controllable valve 12 is opened at a time and thus only one cell to be tested is pressurized with compressed air. After a cell to be tested has been finally tested, the excess pressure, i.e. the compressed air, in the cell to be tested can be released to the atmosphere via a valve (not shown), so that the negative pressure in the chamber's interior can no longer be influenced by the cell to be tested, which has already been tested. This further increases the quality of the test.The devices shown in Figure and Figure for testing the leaks of electrochemical cells have proven to be very informative and very efficient in terms of implementation and handling of the device.- .XWZSriXnoUoPCT / DE2024 / 000036 MAFU Robotics GmbH Straub P822003 / PCT / 1 10.05.2024 List of reference symbols Device for leak testing Electrochemical cell 3 Chamber Housing of the chamber Interior of the electrochemical cell Unit for gas supply Sensor Control unit Alarm unit and display unit 10 Seal 11 Control line 12 Controllable valve 13 Supply line for compressed air.

Claims

1=_nr_en, ,2r0 I : nn 3 l 11 u aljPtPM St nnAlPCT / DE2024 / 000036 MAFU Robotics GmbH Straub P822003 / PCT / 1 10.05.2024 Claims Device for leak testing ( of electrochemical cells ( 2 ), in particular with regard to H2 leak tightness, with a chamber ( for receiving and testing at least one electrochemical cell ( 2 ), wherein the chamber ( is subjected to a negative pressure, wherein a unit for gas supply ( is provided which applies compressed air to an electrochemical cell ( to be tested) introduced into the chamber ( and thus puts the interior ( of the electrochemical cell ( under positive pressure, and wherein a sensor ( is provided which is suitable for detecting a pressure increase in the chamber ( , characterized in that the negative pressure in the chamber ( and the positive pressure in the electrochemical cell ( are selected such that the pressure difference between negative pressure and positive pressure varies periodically, and that the sensor ( with the control unit ( is suitable for detecting and analyzing a periodicity in the pressure increase in the chamber (15-0S-2024-38130801-HauPtPost-0042 PCT / DE2024 / 000036 2. Device for leak testing ( of electrochemical cells ( according to claim 1 ), wherein the generated overpressure Pu of the compressed air in the electrochemical cell ( is over 1 bar.

3. Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4), wherein the negative pressure in the chamber ( is below 10 hPa.

4. Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4), wherein the chamber ( is provided for the simultaneous accommodation and testing of several electrochemical cells ( 2).

5. Device for leak testing ( of electrochemical cells ( according to claim 1 ), wherein the gas supply unit ( is provided for the joint supply of compressed air to the electrochemical cells ( which are introduced into the chamber ( and are to be tested), and thus for placing the interior of the electrochemical cells ( under a common overpressure.Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4, wherein the gas supply unit ( is provided for sequentially placing electrochemical cells ( to be tested) introduced into the chamber ( under an overpressure and thus enabling a sequential test. 15-05-2024-38130801-HauPtpust-0043 PCT / DE2024 / 000036 7. Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4, wherein the sensor ( for detecting a pressure increase is arranged in the chamber ( ).

8. Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4, wherein the sensor ( for detecting a pressure increase is arranged outside the chamber ( ) and is connected via a gas line ( 13) to the negatively pressurized interior ( of the chamber ( ).

9. Device for leak testing ( of electrochemical cells ( according to one of claims 1 to 4, wherein an alarm unit ( ) is assigned to the sensor ( for detecting a pressure increase, which is suitable for emitting an alarm signal upon detection of a pressure increase above a predetermined limit value and / or for storing and / or outputting information on the pressure increase and / or on one or more tested cells ( ).Device for leak testing (of electrochemical cells (2) according to claim 1, wherein the detected pressure increase is detected as a function of time and, upon detection of a pressure increase rate above a predetermined limit value, an alarm signal is output and / or information on the pressure increase and / or on one or more tested cells is stored and / or output.

11. Device for leak testing (of electrochemical cells) according to one of claims 1 to 10, wherein at least one electrochemical cell (a fuel cell or a battery or an electrochemical sensor is supplied with gaseous media for the electrochemical reaction.

12. Device for leak testing (of electrochemical cells (2) according to one of claims 1 to 11, wherein the chamber (has a lock for the supply and / or removal of one or more cells (to be tested).

13. Device for leak testing (of electrochemical cells (2) according to one of claims 1 to 12, wherein the volume of the interior (of the chamber (of the device (is slightly larger, in particular less than 20% larger, than the volume of the electrochemical cell or cells (to be tested) in the chamber (and in particular the volumes are adapted to one another in terms of their shape.Device for leak testing (of electrochemical cells) according to one of claims 1 to 13, wherein the pressure difference varies periodically, in particular in a sinusoidal or sawtooth shape.n_r_rt=2,1_1›. X , .)AN)Ad. PCT / DE2024 / 000036 15. Device for leak testing (of electrochemical cells) according to one of claims 1 to 14, wherein the amplitude of the change in the pressure difference between negative pressure and positive pressure is in a range of one or two orders of magnitude of the pressure difference, in particular by a factor of approximately.

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