Method and system for checking for leaks in a battery housing

Abstract

The invention relates to a method for checking for leaks in a battery housing (10), comprising the steps of: carrying out a general check in terms of the tightness of the battery housing (10), in which a total leakage of the gas is determined, measuring how much of the gas the battery housing (10) lets out; according to the result of the general check: specifying at least one parameter for a detailed check in terms of the tightness of the battery housing (10) in order to locate leaks in the battery housing (10); carrying out the detailed check in order to pinpoint at least one leak in the battery housing (10), in which, at least in a predefined region (20) of the battery housing (10), using a sensor unit (16) (sniffer tip), according to the at least one predefined parameter, it is checked where in the region (20) the gas passes out of the battery housing (10). The invention also relates to a system (12) which is designed to carry out a method of this type.

Description

[0001] METHOD AND SYSTEM FOR LEAK TESTING A BATTERY CASING

[0002] Technical area

[0003] The present invention relates to a method and system for leak testing of a battery housing.

[0004] State of the art

[0005] During the production of traction batteries for motor vehicles, it is often necessary to test the associated battery housings for leaks, for example, to reliably prevent the leakage or ingress of media. The leak test is usually only performed after the battery housing has been sealed. Furthermore, the fully assembled battery housing can contain different sealing materials, seal geometries, and seal types. These circumstances can lead to a test method not being suitable for all possible types of leaks. Furthermore, it is generally desirable to be able to perform such leak tests particularly quickly and reliably.

[0006] Description of the invention

[0007] The object of the invention is to enable the most reliable and efficient leak test possible for a battery housing.

[0008] This object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures.

[0009] In the method according to the invention for testing the leak tightness of a battery housing, the following steps are carried out: carrying out a rough test with regard to the leak tightness of the battery housing, in which a total leakage of the gas is determined by measuring how much of the gas passes through the battery housing overall; depending on the result of the rough test: specifying at least one parameter for a fine test with regard to the leak tightness of the battery housing for localizing leaks on the battery housing; carrying out the fine test for locating at least one leak on the battery housing, in which at least in a predetermined area of ​​the battery housing it is checked with the help of a sensor device according to the at least one predetermined parameter where in the area the gas passes through the battery housing.

[0010] The battery housing can, in particular, be a battery housing for a traction battery of an electrically powered motor vehicle. However, it can also be other types of battery housing. The rough test can also be understood as a rough leak test. The rough test can, for example, be carried out in the form of a pressure test, a differential pressure test or even a mass flow test. The rough test therefore determines the aforementioned total leakage. This means that it is checked whether and to what extent the battery housing is leaking. This does not yet involve locating a potentially leaky point in the battery housing. The rough test initially only determines how much gas passes through the battery housing overall. During the process, it can be provided, in particular, that the battery housing is closed.

[0011] Depending on the result of the rough test, at least one parameter is specified for a detailed test regarding the tightness of the battery housing to locate leaks on the battery housing. For example, standard values ​​can be stored for carrying out the detailed test. For example, if it is determined during the rough test that there is no major leak, the procedure can also provide for these standard values ​​to be simply retained unchanged. If, on the other hand, a major leak is determined during the rough test, it can then be provided for these standard values ​​or at least one standard value or parameter to be adjusted for the detailed test depending on the rough test. For example, it can be specified that from approx. 10 -5 mbar * l / s is assumed to be a major leak. However, it can also be specified that other values ​​are specified from which a major leak is assumed, such as 10-2 or 10' 3mbar * l / s. Following the rough test, the said fine test is carried out to locate at least one leak in the battery housing. In at least one predetermined area of ​​the battery housing, a sensor device, which can also be referred to as a sniffer tip, is used to check according to the at least one predetermined parameter where in the area the gas passes through the battery housing, in particular the closed battery housing. The fine test is therefore about the specific location of a leak, i.e. the said leak. By specifying the at least one parameter for the fine test depending on the result of the rough test, the fine test can be carried out particularly efficiently and, at the same time, particularly reliably.The invention is based, among other things, on the realization that it makes a difference for the detailed inspection whether a relatively large or relatively small total leakage was determined during the rough inspection. Therefore, the detailed inspection is parameterized in accordance with the invention so that, depending on the total leakage determined during the rough inspection, it can be carried out particularly quickly while still being very reliable.

[0012] During the fine inspection, the leak, if present, is located. The leak can also be referred to as a leak, for example in the form of a leak, opening, gap, hole or similar, through which air or other media can get into or out of the battery housing. As mentioned, at least one area is specified for the fine inspection, which is checked using the sensor device, in particular using a sniffer tip. This area can include, for example, weld seams, butt joints, screw joints or other connection points where leaks can occur. The method according to the invention therefore provides for a combined rough inspection and fine inspection in order to check the battery housing for leaks. By coordinating orBy matching the parameters of the fine test to the result of the rough test, the leak test on the battery housing can be carried out particularly reliably and yet quickly.

[0013] One possible embodiment of the invention provides that the travel speed of the sensor device along the area of ​​the battery housing to be examined during the detailed inspection is specified to be greater, the greater the total leakage determined. Analogously, it can also be provided that the travel speed of the sensor device along the area of ​​the battery housing to be examined during the detailed inspection is specified to be lower, the smaller the total leakage determined during the coarse inspection. Therefore, if, for example, a coarse leak is detected, the travel speed of the sniffer tip can be significantly increased for the detailed inspection, which can also be referred to as a sniffer test, in order to locate the location of the coarse leak.The invention is based on the finding that a large leak causes a sufficient amount of gas to escape from the battery casing, which can be detected even at a relatively high travel speed of the sniffer tip or, more generally, the sensor device. This allows for particularly rapid localization of any large leak, resulting in less gas being added to the battery casing and potentially even being extracted from the battery casing earlier, thus significantly reducing gas contamination of the measurement environment.

[0014] A further possible embodiment of the invention provides that the distance between the sensor device and the area of ​​the battery housing to be examined during the detailed inspection is specified to be greater, the greater the determined total leakage is. Analogously, it can also be provided that the distance between the sensor device and the area of ​​the battery housing to be examined during the detailed inspection is specified to be smaller, the smaller the determined total leakage is during the rough inspection. If the distance between the sensor device, in particular in the form of the said sniffer tip, and the area of ​​the battery housing to be examined is selected to be relatively large, the possibility of the sensor device colliding with the battery housing during the detailed inspection can be ruled out or relatively reliably prevented.The battery housing can have a wide variety of shapes, projections, and the like in the area to be examined, which can make collision-free inspection of the battery housing with the sensor device more difficult. The invention is based on the finding that, for example, in the case of a high total leakage, it can be assumed that leaks can still be reliably located even if the sensor device is located at a greater distance from the area of ​​the battery housing to be examined during the fine inspection. The distance of the sensor device is therefore adjusted taking into account the total leakage determined during the rough inspection. A further possible embodiment of the invention provides that the gas comprises a test gas, for example in the form of helium, forming gas, coolant, or the like, wherein the sensor device is designed to detect the test gas.The sensor device can, for example, comprise a gas detector, a mass spectrometer, or the like. The test gas can be detected particularly reliably during the detailed inspection, allowing any leaks, i.e., leaks, to be identified with particular reliability.

[0015] Another possible embodiment of the invention provides for the use of 5 to 20% of test gas relative to the total volume of the battery housing. This results in a relatively low test gas concentration, which, however, is still sufficient due to the process, to reliably detect any leaks, i.e., leaks, in the battery housing during the detailed inspection.

[0016] A further possible embodiment of the invention provides for the gas to be tempered relative to the ambient temperature, with the sensor device comprising a temperature sensor. The gas can, for example, be cooled or heated before being used for leak testing during the rough test and subsequent fine test. By tempering the gas relative to the ambient temperature, i.e., the test environment in which the battery housing is located, and before the actual rough test and fine test are performed, the tempered gas can be detected particularly reliably in order to find any leaks during the fine test.

[0017] In a further possible embodiment of the invention, the larger the total volume of the battery housing, the greater the temperature difference between the gas and the ambient temperature. The invention is based on the finding that the temperature difference required for a reliable leak test depends on the size of the volume to be tested. The temperature of the tempered gas should not adjust to the ambient temperature too quickly, so that the tempered gas can be easily located, especially during the detailed inspection, to pinpoint leaks.

[0018] A further possible embodiment of the invention provides that the temperature difference between the gas and the ambient temperature is selected to be smaller the higher the test pressure to which the battery housing is subjected by the gas. In this context, the invention is based on the finding that the effect of cooling the gas through expansion is pressure-dependent. By adjusting the temperature difference between the gas and the ambient temperature depending on the test pressure, it can be ensured that, particularly during the final test, the temperature difference between the gas and the ambient temperature is still large enough to reliably detect any leaks in the battery housing.

[0019] A further possible embodiment of the invention provides that the battery housing is not evacuated before the rough test. This is possible if the gas comprises a test gas and / or is kept at a correspondingly high temperature compared to the ambient temperature. By eliminating the evacuation before the rough test, a step that might otherwise be necessary for leak tests on battery housings is eliminated. This makes the process particularly simple and less complex to carry out.

[0020] The system according to the invention for leak testing a battery housing is designed to carry out the method according to the invention or possible embodiments of the method according to the invention. The system comprises, in particular, means designed to carry out the method. In particular, the system can have a testing device for performing the rough test, said sensor device for performing the fine test, and a control device configured to specify at least one parameter for the fine test depending on the result of the rough test.

[0021] Further advantages, features, and details of the invention can be derived from the following description of possible embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective specified combination, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] Short character description

[0023] The drawing shows, in the single figure (Fig. 1), a schematic representation of a battery housing which is subjected to a leak test. In Fig. 1, a battery housing 10 is shown in a highly schematic manner. The battery housing 10 can, for example, be a housing for a traction battery of an electrically powered motor vehicle. However, the battery housing 10 can also be any other battery housing. In addition, a system 12 is schematically indicated which is designed to test the leaks of the battery housing 10. The system 12 comprises a test device 14 for carrying out a rough test, a sensor device 16, which can be or comprise a sniffer tip, for carrying out a fine test and a control device 18 which is configured to specify or change at least one parameter for the fine test depending on the result of a rough test.A method for testing the tightness of the battery housing 10 is explained in more detail below.

[0024] First, the test device 14 performs a rough test for the tightness of the battery housing 10. This determines the total leakage of a gas introduced, for example, into the battery housing 10 by measuring how much of the gas passes through the closed battery housing 10, for example, exits to the outside. Depending on the result of the rough test, the control device 18 specifies at least one parameter for the detailed test for the tightness of the battery housing 10 to locate any leaks, i.e., leaks, on the battery housing 10. The detailed test is then performed using the sensor device 16. The detailed test aims to locate at least one leak, i.e., a leaky spot, on the battery housing 10.During the precision inspection, the sensor device 16, which can be a sniffer tip, for example, is moved past an area 20 to be inspected according to at least one previously specified parameter, where leaks, i.e., leaky spots, can be expected. Said leaks can generally be leaks, openings, gaps, holes, or the like through which, for example, air can enter or exit the battery housing 10. The area 20 to be inspected during the precision inspection can, for example, contain weld seams, joints, screw joints, or other connection points. Leaks can be expected to occur particularly at such locations.For example, the travel speed v of the sensor device 16 along the area 20 of the battery housing 10 to be examined during the fine inspection can be specified to be greater the larger the total leakage determined during the coarse inspection. Conversely, the travel speed v can also be specified to be lower the smaller the total leakage determined.

[0025] In addition, it can also be provided that a distance h of the sensor device 16 from the area 20 to be examined during the fine test is specified to be greater the larger the determined total leakage is and vice versa.

[0026] The gas used can be, for example, a test gas, forming gas, refrigerant, or the like. In this case, the sensor device 16 is designed to detect said test gas. For this purpose, the sensor device 16 can, for example, comprise a gas detector, a mass spectrometer, or the like. Relative to the total volume of the battery housing 10, the test gas concentration can be in the range of 5 to 20%.

[0027] The gas used can also be, for example, ambient air, which is tempered relative to the environment, in which case the sensor device 16 comprises a temperature sensor. The gas, which in this case can in particular be ambient air, can, for example, be cooled or heated accordingly before the rough test so that the temperature difference is sufficiently large that the sensor device 16 can still reliably detect tempered air escaping from the battery housing 10 in the area 20 during the fine test, for example, in order to reliably locate any leaks that may be present.

[0028] It can be provided that the temperature difference between the gas used, for example in the form of ambient air, and the environment is selected to be greater the larger the total volume of the battery housing 10. This can ensure that, for example, with a very large volume of the battery housing 10, it can still be ensured that the tempered gas has a correspondingly large temperature difference for long enough so that, during the final test, the gas used can be reliably detected based on the temperature difference in order to determine and localize any leaks that may be present in the battery housing 10. It can also be provided that the temperature difference between the gas and the environment is selected to be smaller the greater the test pressure to which the battery housing 10 is pressurized by the gas.This ensures, depending on the pressure, that the temperature difference of the gas is still sufficient to reliably detect it during the final test, so that any leaks present in area 20 of the battery housing 10 can also be reliably detected by the sensor device 16. Furthermore, it can also be provided that the battery housing 10 is not evacuated at all before the rough test. This can be achieved by using the gas containing test gas and / or by controlling the temperature of the gas, which makes evacuation of the battery housing 10 before the rough test unnecessary.

[0029] Overall, the described method or system 12 enables a particularly reliable and rapid leak test of the battery housing 10.

[0030] LIST OF REFERENCE SYMBOLS

[0031] 10 Battery housing 12 System

[0032] 14 Test facility

[0033] 16 Sensor device

[0034] 18 Control device

[0035] 20 Range h Distance v Travel speed

Claims

PATENT CLAIMS 1. A method for leak testing a battery housing (10), comprising the steps: Carrying out a rough test with regard to the tightness of the battery housing (10), in which a total leakage of the gas is determined by measuring how much of the gas passes through the battery housing (10) in total; depending on the result of the rough test: specifying at least one parameter for a fine test with regard to the tightness of the battery housing (10) for locating leaks on the battery housing (10); Carrying out the fine test to locate at least one leak on the battery housing (10), in which at least in a predetermined area (20) of the battery housing (10) it is checked with the aid of a sensor device (16) (sniffer tip) according to the at least one predetermined parameter where in the area (20) the gas passes through the battery housing (10).

2. Method according to claim 1, characterized in that a travel speed (v) of the sensor device (16) along the area (20) of the battery housing (10) to be examined during the fine test is specified to be greater, the greater the total leakage determined is.

3. Method according to claim 1 or 2, characterized in that a distance (h) of the sensor device (16) from the area (20) of the battery housing (10) to be examined during the fine test is specified to be greater, the greater the total leakage determined is.

4. Method according to one of the preceding claims, characterized in that the gas comprises a test gas and the sensor device (16) is designed to detect the test gas. Method according to claim 4, characterized in that five to 20 percent of test gas is used based on the total volume of the battery housing (10). Method according to one of the preceding claims, characterized in that the gas is tempered compared to the ambient temperature, wherein the sensor device (16) comprises a temperature sensor. Method according to claim 6, characterized in that the larger the total volume of the battery housing (10), the greater the temperature difference between the gas and the ambient temperature is selected. Method according to claim 6 or 7, characterized in that the higher the test pressure to which the battery housing (10) is pressurized by the gas, the smaller the temperature difference between the gas and the ambient temperature is selected. Method according to one of claims 4 to 8, characterized in that the battery housing (10) is not evacuated before the rough test.System (12) for leak testing a battery housing (10), which is designed to carry out a method according to one of the preceding claims.

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