Lid arrangement with a forming gas adapter for supplying a forming gas into a housing and method for leak testing a housing

Abstract

A forming gas adapter (26) is provided for supplying a forming gas into a housing (10) of a motor vehicle, comprising a connection opening (34) for connecting a fluid line for forming gas, an outlet opening (36) for introducing the forming gas into the housing (10), a fluid channel (32) communicating fluidically with the connection opening (34) and the outlet opening (36), a radially projecting mounting flange (28) from the fluid channel (32) for a fluid-tight connection to a cover (14) that can be attached to the housing (10), at least one clamping leg (46) movably projecting from the fluid channel (32) and passable through a cover opening (16) of the cover (14) for detachable attachment to the cover (14), and an adjusting element (50) for adjusting the at least one clamping leg (46) between a mounting position in which the at least one clamping leg (46) passes through the cover opening (16) of the cover. (14) can be passed through, and a holding position,in which at least one clamping leg (46) prevents relative movement of the mounting flange (28) to the cover (14). This allows for a simple leak test of the motor vehicle housing (10) after repair or maintenance while it is installed.

Description

[0001] The invention relates to a lid assembly with a forming gas adapter, by means of which a forming gas can be supplied into a housing, in particular for an electric motor, of a motor vehicle in order to perform a leak test. The invention further relates to a motor vehicle with such a lid assembly and to a method for leak testing a housing.

[0002] DE 10 2019 131 672 B3 describes a method for leak testing a housing made of grey cast iron for an internal combustion engine of a motor vehicle, in which the closed housing is pressurized with compressed air and in the event that a defect caused by a void in the housing causes a pressure drop, in a subsequent test step the closed housing is pressurized with a forming gas in order to find the leakage point by detecting the escaping forming gas with the aid of a sensor.

[0003] DE 10 2020 100 271 A1 describes a housing for an electric motor vehicle manufactured by injection molding of plastic, wherein the housing has a cover which is fitted in a sealing manner to an axial end of a rotor of the electric motor, in which a rotor position sensor and a pressure equalization element are integrated.

[0004] JP 2000 - 071 178 A shows an adapter for connecting a cable to a housing, in which elastic claws are inserted into an opening of the housing and are elastically spread in the opening by means of an axially movable cone, whereby an adapter body is pressed tightly against the housing.

[0005] From DE 10 2022 110 763 A1, a housing for an electric motor of a motor vehicle is known, wherein a cover opening for the installation of a pressure equalization element is provided in one of the housing covers. Before the final installation of the pressure equalization element, a leak test is carried out by placing a test probe on the cover opening and creating overpressure / underpressure. After the test, the pressure equalization element is then installed.

[0006] There is a need to check the housing of a motor vehicle for leaks even after a repair or maintenance.

[0007] The object of the invention is to demonstrate measures that enable a simple leak test of a motor vehicle housing after a repair or maintenance.

[0008] The problem is solved according to the invention by a lid arrangement with the features of claim 1, a motor vehicle with the features of claim 7, and a method with the features of claim 8. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention, the scope of protection being determined by the claims.

[0009] One aspect of the invention relates to a cover arrangement comprising a cover for covering an opening in a motor vehicle housing, wherein the cover has a cover opening for fluid-tight clipping of a pressure equalization element, and a forming gas adapter fluid-tightly inserted in the cover opening for supplying a forming gas into a housing, in particular for an electric motor, of a motor vehicle, with a connection opening for connecting a fluid line for forming gas, an outlet opening for introducing the forming gas into the housing, a fluid channel fluidically communicating with the connection opening and the outlet opening, and a mounting flange projecting radially from the fluid channel for fluid-tight mounting on a cover that can be attached to the housing.at least one clamping leg movably extending from the fluid channel and / or mounting flange and passable through a lid opening for detachable fastening to the lid, and an adjusting element for adjusting the at least one clamping leg between a mounting position in which the at least one clamping leg can be passed through the lid opening, and a holding position in which the at least one clamping leg prevents relative movement of the mounting flange to the lid.

[0010] It has been recognized that during repair or maintenance, particularly of a directly cooled electric motor for the electric drive of a motor vehicle, there is a need to perform a leak test of the housing opened during the repair or maintenance, especially to ensure that no cooling medium from the stator area of ​​the electric motor can leak into the rotor area. Unlike a leak test of the electric motor housing during the assembly process of the motor vehicle, during a subsequent repair or maintenance, the electric motor is installed in the vehicle's powertrain, so that the entire housing of the electric motor is generally not accessible for a leak test.If access has to be created during repair or maintenance, this is time-consuming and creates the risk that damage to the housing leading to leakage may occur during the steps to create access and / or during the steps to remove access.

[0011] Furthermore, it was recognized that at least the housing for the electric motor intended for the electric drive of the motor vehicle typically has a separate cover located in an easily accessible position. This cover, in turn, may have an opening, for example, to allow the mounting of a rotor bearing, a rotor position sensor, and / or a pressure equalization element. In the invention, this opening can be functionalized to allow the insertion of the forming gas adapter for leak testing, instead of the component normally inserted in the opening, such as the pressure equalization element. It was also recognized that the component normally inserted in the opening can be easily removed by simply disassembling the cover as a whole.Once the lid is reattached to the housing in a fluid-tight manner and the forming gas adapter is inserted in place of the normally used component, a leak test can easily be performed using forming gas. Since the forming gas adapter is detachably attached to the lid for the leak test, it can be easily removed afterward without having to disassemble the entire lid and thus eliminate the seal between the lid and the rest of the housing. Instead, the normally used component or a new, identical component can be inserted into the lid opening in the usual way, for example, by clipping it in place.Due to its good accessibility, the normally used component can be installed without significant difficulties, so no impairment of the seal between the cover and the normally used component is to be expected during installation. The interaction of the actuator with the at least one clamping leg allows for a fluid-tight and releasable fastening of the forming gas adapter in the easily accessible opening of the housing cover, thus enabling simple leak testing of the vehicle housing after repair or maintenance while it is still installed.

[0012] The forming gas adapter allows forming gas to pass through the lid and / or the housing, enabling the gas to be introduced from an external gas source into the housing. The forming gas adapter can be kept on hand in a workshop, for example, as a cost-effective tool for performing a leak test of the housing after repairs or maintenance.

[0013] The forming gas is, in particular, a gas mixture that preferably contains various gases with different penetrating properties. The forming gas preferably contains nitrogen (N₂) and / or argon (Ar), and preferably also hydrogen (H₂). The mass fraction of hydrogen in the forming gas is particularly preferably less than 5.5% to ensure that the forming gas is non-flammable. Due to the very small molecular size of hydrogen gas, it can relatively easily pass through an inadequately sealed leak. The escape of hydrogen gas is generally detected using a suitable probe. However, since the housing to be leak-tested may not be sufficiently accessible for a hand-held probe, it is preferred that the hydrogen concentration in the introduced forming gas be measured in the area of ​​the easily accessible forming gas adapter.If a drop in hydrogen concentration is measured inside the housing, this indicates insufficient sealing, which is sufficient information during repair or maintenance to recognize the need for further measures.

[0014] The housing should provide a high degree of tightness, particularly to prevent leakage of fluids, such as gases and / or liquids. The housing is preferably for an electric motor of a motor vehicle, the electric motor being intended, in particular, for the electric propulsion of the motor vehicle. The electric motor can be directly cooled, in particular by means of a coolant, so that the housing can be filled with the coolant during operation, and leakage of the coolant is to be prevented by a sufficiently tight seal of the housing. In particular, it should be prevented that coolant for a directly cooled stator of the electric motor can leak into any area of ​​the rotor of the electric motor.In principle, however, the housing can be part of other motor vehicle components, for example high-voltage components, especially motor vehicle components that have directly cooled components and where leakage should be prevented.

[0015] The connection opening of the forming gas adapter is, in particular, a standardized connection for attaching a gas-carrying line. Specifically, the connection opening forms a female part of a connection technology.

[0016] The outlet opening of the forming gas adapter can point towards the interior of the housing, allowing the introduced forming gas to pass into the interior. It is possible that one opening plane of the outlet lies within a wall of the cover and / or the housing, and that at least one clamping leg, and possibly the actuating element, protrudes from the outlet opening towards the interior of the housing.

[0017] The fluid channel establishes a fluidic connection between the inlet and outlet openings. The fluid channel is formed by the material of the forming gas adapter and can define a cavity by allowing the forming gas to pass through it. This cavity can, in particular, be based on a hollow cylinder. The fluid channel can, in particular, form a type of pipe.

[0018] The mounting flange is, in particular, integrally formed with the fluid channel. The mounting flange can project from the fluid channel in a radial direction, preferably in a circumferential direction. The mounting flange can provide an axial surface that can be pressed against an outer surface of the cover, particularly to contribute to a fluid-tight seal between the forming gas adapter on the one hand and the cover and / or the housing on the other. In principle, the mounting flange can also be used for a fastening mechanism with the cover and / or the housing, whereby it is preferred that the forming gas adapter be fastened to the cover solely by means of the at least one clamping leg and the adjusting element.

[0019] The cover can, in particular, provide a fluid-tight seal for a housing opening and simultaneously allow a component inserted into the cover opening to pass into the interior of the housing. Preferably, the cover is located on an axial side of the housing, more preferably essentially coaxial with an axis of rotation of a rotor located in the housing. Most preferably, the rotor has a rotor shaft that extends out of the housing on the axial side facing away from the cover.

[0020] The lid opening may, in particular, have a standardized mounting geometry designed, for example, to allow components to be clipped in. The lid opening may also provide access to the interior of the housing.

[0021] At least one clamping arm can be threaded into the lid opening during assembly of the forming gas adapter and subsequently moved into the holding position by actuating the actuator. Due to the relative mobility of the clamping arm compared to the rest of the forming gas adapter and the lid, a positive and / or frictional locking of the forming gas adapter in the lid opening can be achieved. In a particularly simple assembly technique, the forming gas adapter can be pressed fluid-tight against the lid with its mounting flange and, in the pressed-in state, clamped in the lid opening by means of the radially outward-moving clamping arms.To relieve stress on the clamping points of the clamping leg in the lid opening, a positive-locking engagement and / or gripping mechanism can also be provided to limit any potential loosening of the sealing point to a defined minimum, while still ensuring sufficient tightness. Preferably, at least three, four, five, or six clamping legs are provided, which are particularly designed as identical parts.

[0022] The actuator can cause the clamping arm to move between the mounting position and the holding position. For this purpose, an actuation mechanism can be provided to operate the actuator, allowing an installer to interact with it to move the clamping arm. The actuator can, for example, be supported by the material of the fluid channel to apply and, if necessary, maintain the force required to move the clamping arm.

[0023] In particular, the at least one clamping leg is pivotally mounted to the fluid channel, especially in a common axial area with the mounting flange, in a manner that prevents it from falling out. Preferably, the at least one clamping leg is also displaceable in the axial direction of the fluid channel, i.e., essentially in the longitudinal direction of the fluid channel. For example, the respective clamping leg has a ball joint or a hook to allow, on the one hand, at least limited pivoting and, on the other hand, to secure the clamping leg in place. Preferably, the actuating element can block excessive pivoting of the clamping leg, so that the clamping leg can be easily mounted in an extremely pivoted relative position, whereby precisely this extremely pivoted relative position cannot be reached again after the actuating element has been mounted.The pivoting of the clamping arms allows clamping on an inner side of the cover opening that faces radially inwards. The axial displacement of the clamping arms enables the cover and / or a housing wall to be pressed between the clamping arm and the mounting flange, preferably in a form-fitting and / or captive manner.

[0024] Preferably, the adjusting element for adjusting the at least one clamping leg in the fluid channel is movable with a movement component in the axial direction of the fluid channel, wherein, in particular, the adjusting element is screwed into the fluid channel. Through the axial movement, especially helical movement, the adjusting element can change its relative position to the at least one clamping leg and thereby force the movement of the clamping leg between the mounting position and the holding position. For this purpose, for example, a suitably shaped part of the adjusting element can slide along the clamping leg and, as it slides, push and / or pull the clamping leg into the mounting position and / or the holding position. The screw connection of the adjusting element in the fluid channel allows for a defined movement of the adjusting element, while simultaneously providing axial support for forces acting on the adjusting element against an internal thread of the fluid channel.For example, the thread is designed as a sawtooth thread or flat thread in order to better support the (reaction) forces occurring via the flat side of the internal thread of the fluid channel facing the interior of the housing.

[0025] The actuating element preferably has a tool contour for the positive engagement of a tool for actuating the actuating element, wherein the tool contour is particularly accessible via the connection opening. The tool contour can, for example, allow the positive engagement of a screwdriver or can be designed as an internal hexagon. If the connection opening is provided in the longitudinal direction of the fluid channel, particularly essentially coaxially, the tool intended for actuating the actuating element can be threaded into the connection opening to ultimately reach the tool contour of the actuating element. The connection opening can thus already provide a coarse centering of the tool, thereby simplifying handling during actuation of the actuating element.

[0026] In particular, the actuator has a conical body for spreading the at least one clamping leg into the holding position, wherein the actuator has at least one passage opening for the passage of the forming gas. The clamping leg can slide off the conical body during a relative displacement of the actuator and thereby pivot in a radial direction. In particular, the clamping leg can be wedged between the conical body and an inner surface of the cover opening to achieve at least a frictional connection with the cover, preventing relative movement of the mounting flange to the cover. To prevent the contact of the conical body with the clamping leg from obstructing or unnecessarily reducing the flow cross-section of the fluid channel, the at least one passage opening in the actuator, in particular in the conical body, ensures the flow of the forming gas through the actuator.

[0027] Preferably, the at least one clamping leg has a retaining collar for engaging behind the lid opening in the holding position and / or for pressing against a sliding surface of the lid in the holding position. The retaining collar can be designed as a projection extending substantially at right angles from the rest of the clamping leg, so that a plurality of identically shaped clamping legs in the area of ​​the retaining collars form a ring that is repeatedly interrupted in the circumferential direction. By engaging behind the lid opening in the holding position, the retaining collar can provide a positive locking mechanism to prevent movement in the axial direction.Furthermore, it is possible to press the cover and / or the housing between the retaining collar and the mounting flange, whereby in particular an amount of axial contact force in the holding position is so high that a sufficiently fluid-tight seal between the forming gas adapter and the cover is ensured.

[0028] The fluid channel preferably has a connection port, particularly one projecting vertically upwards, for connecting a forming gas probe that communicates fluidically with the fluid channel. The forming gas probe can, in particular, measure the hydrogen concentration in the forming gas. Since the internal volume of the fluid channel transitions into the internal volume of the housing, any change in hydrogen concentration caused by a hydrogen gas leak will also equalize within the interior of the fluid channel. The forming gas probe can detect a drop in the hydrogen concentration in the forming gas and thus indicate the presence of an insufficient seal of the housing.Since hydrogen is a particularly light gas, it tends to settle vertically upwards against the direction of gravity. Therefore, the forming gas probe provided in the vertically projecting connection nozzle cannot measure any decrease in hydrogen concentration caused by natural segregation of the hydrogen gas. The connection nozzle can be integrally formed with the fluid channel. However, it is also possible to attach the connection nozzle as a separate component, detachably to the rest of the forming gas adapter. This allows for the use of a differently designed forming gas probe with a different connection nozzle adapted to the shape of that probe.

[0029] In particular, the mounting flange has an axially acting seal facing the cover and / or the fluid channel has a radial seal facing the cover opening, acting at least partially in a radial direction. The axial seal and / or the radial seal ensure sufficient tightness of the forming gas adapter to the cover. In particular, the radial seal can provide a rough centering of the forming gas adapter in the cover opening, thus simplifying the installation of the forming gas adapter in the cover.

[0030] Preferably, the lid opening has an inclined sliding surface on an inner axial side facing the housing, allowing the at least one clamping leg to slide into a holding position that engages behind the lid. When the clamping leg, particularly with its retaining collar, engages the sliding surface, it can slide off the sliding surface if the applied clamping force increases. The angle of inclination of the sliding surface and / or the counter-surface of the clamping leg engaging the sliding surface can be dimensioned such that self-locking is reliably prevented under the expected friction conditions.By sliding the clamping arm along the sliding surface of the lid opening, the mounting flange is automatically drawn towards the lid and pressed against it without any additional force being applied. This continues until either further pressure on the mounting flange is blocked, despite the elasticity of the provided seals, and the normal force exerted by the clamping arm secures the forming gas adapter firmly in the holding position, or the retaining collar of the clamping arm leaves the sliding surface and snaps into a holding position that engages behind the lid. This allows for a particularly simple and user-friendly installation of the forming gas adapter in the lid with a sufficiently high level of tightness.

[0031] Another aspect of the invention relates to a motor vehicle with a housing, in particular for an electric motor, wherein the housing has a cover arrangement which can be designed and further developed as described above. Through the interaction of the actuating element with the at least one clamping leg, a fluid-tight and releasable fastening of the forming gas adapter in the easily accessible cover opening of the housing cover can be achieved, thus enabling a simple leak test of the motor vehicle housing after a repair or maintenance in the installed state.

[0032] A further aspect of the invention relates to a method for leak testing a housing, in particular for an electric machine, of a motor vehicle, in which a cover, in particular on an outer axial side, is attached to the housing, a pressure equalization element inserted in a cover opening of the cover is removed, a forming gas adapter provided for connecting a gas source, which may be designed and further developed in particular as described above, is fluid-tight and detachably mounted in the cover opening, the cover is fluid-tightly attached to the housing, in particular to the outer axial side of the housing, a forming gas is introduced into the housing via the forming gas adapter, it is checked whether there is a leakage of forming gas from the housing, the forming gas adapter is removed from the cover opening, while the cover, in particular on the outer axial side of the housing, remains attached to the housing.and the same or a different pressure equalization element is fluid-tightly attached in the cover opening. The method can preferably be designed and further developed as described above. Through the interaction of the actuating element with the at least one clamping leg, a fluid-tight and releasable attachment of the forming gas adapter in the easily accessible cover opening of the housing cover can be achieved, thus enabling a simple leak test of the motor vehicle housing after a repair or maintenance in the installed state.

[0033] The method is particularly preferably carried out while the housing is installed in a motor vehicle. The method can be used especially during the repair and / or maintenance of the housing, and preferably during the repair and / or maintenance of an electric machine comprising the housing. The electric machine is specifically designed for the electric propulsion of the motor vehicle. Preferably, the electrical components provided in a stator of the electric machine, for example electromagnets and / or power electronics, are directly cooled with a coolant.

[0034] The invention is now explained by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination, and the scope of protection is defined by the claims. The drawings show: Fig. 1: A schematic external view of an axial side of a housing for an electric motor vehicle, Fig. 2: a schematic sectional view of a lid of the housing made of Fig. 1, Fig. 3: A schematic perspective view of a pressure equalization element of the lid made of Fig. 2 and Fig. 4: A schematic half-section view of the lid of the housing made of Fig. 1 with a pressure equalization element instead of the Fig. 3 forming gas adapters used.

[0035] The in Fig. The housing 10 shown in Figure 1 can contain and / or enclose a directly cooled electric motor for the electric drive of a motor vehicle, particularly one designed as a sports car or racing car, in a fluid-tight manner, ensuring in particular that leakage of the coolant used for cooling the electric motor is reliably prevented even after repair or maintenance. The housing 10 has a cover 14 with a cover opening 16 on an axial side 12 pointing away from a shaft passage of a rotor shaft of the electric motor. This cover 14 can be screwed to the housing 10.

[0036] As in Fig. As shown in Figure 2, a pressure equalization element 20, communicating with an interior 18 of the housing 10, can be clipped into the lid opening 16. If overpressure should occur inside the housing 10, it can be released via the pressure equalization element 20. During the assembly of the Fig. According to the pressure equalization element 20 shown in section 3, the pressure equalization element 20 can be pressed against the elasticity of a seal 22 of the pressure equalization element 20 in the lid opening until the locking hooks 24 snap radially outwards to create the clip connection and engage the lid 14 fluid-tight and securely.

[0037] If a leak test of the housing 10 is to be carried out after a repair or maintenance using a forming gas, the pressure equalization element 20 should be replaced by a forming gas adapter 26 for the duration of the leak test. For this purpose, the cover 14, together with the inserted pressure equalization element 20, can first be removed from the housing 10, in particular by unscrewing it. This exposes the locking hooks 24 of the pressure equalization element 20. The locking hooks 24 of the locking hook 24 can be squeezed together by hand to pull the pressure equalization element 20 out of the opening 16 of the cover 14. If a locking hook 24 should break off during this process, the damaged pressure equalization element 20 can be replaced with a new one. Otherwise, it is possible to reuse the pressure equalization element 20 later.

[0038] Once the pressure equalization element 20 is removed, it is possible to first attach the forming gas adapter 26 to the cover 14 and then attach the cover 14 together with the forming gas adapter 26 to the housing 10, or to first attach the cover 14 to the housing 10 and only attach the forming gas adapter 26 to the cover 14 after the cover 14 has been attached to the housing 10. When the forming gas adapter 26 has been attached to the cover 14, the following results: Fig. 4 depicted states.

[0039] As in Fig. As shown in Figure 4, the forming gas adapter 26 has a contact flange 28 pressed against the cover 14, which presses against an axially acting seal 30 designed as a pocket seal or O-ring. The contact flange 28 projects radially outwards in an annular manner from a fluid channel 32, with which the contact flange 28 is preferably integrally formed. The fluid channel 32 extends along its longitudinal direction, which coincides with an axial direction, from a connection opening 34 to an outlet opening 36 leading to the interior 18 of the housing 10. A fluid connection 38 of a fluid line can be inserted into the connection opening 34, which is preferably standardized, in a fluid-tight manner to introduce forming gas into the interior 18 of the housing 10.A connecting nozzle 40 can protrude from the fluid channel 32, particularly with a portion extending vertically upwards, in which a forming gas probe can be inserted, which can measure in particular a change in the proportion of hydrogen gas in the forming gas in order to be able to conclude, in the event of a drop in the hydrogen concentration in the forming gas, that there is a leak and thus an insufficient seal of the housing 10.

[0040] The lid opening 16 of the lid 14 has an inner surface 42, which, for example, has a conical area for pressing against a radial seal 44 acting at least partially in a radial direction, thereby enabling the forming gas adapter 26 to be centered in the lid 14 via the radial seal 44 acting on the conical inner surface 42. The forming gas adapter 26 has clamping legs 46 pivotally connected in a radial direction to the fluid channel 32, which protrude from the outlet opening 36 and are located in the Fig.In the holding position shown in Figure 4, the cover 14 is engaged in a form-fitting and captive manner by a retaining collar 48. For this purpose, an actuating element 50 can be axially displaced by a tool engaging a tool contour 52, in particular by being screwed into the fluid channel 32. The actuating element 50 has a conical body 52 which, through the axial displacement of the actuating element 50 relative to the clamping leg 46, presses the clamping leg 46 from a more central mounting position into the radially outward pivoted holding position. In this case, it is possible that the clamping leg 46, in particular with its retaining collar 48, is pressed against a strongly chamfered sliding surface 54 on the inner side 42 of the cover opening 16 and, due to the chamfer angle of the sliding surface 54, slides along the sliding surface 54.As the mounting flange 28 slides along the sliding surface 54, it is pressed ever more firmly against the cover 14 until the retaining collar 48 leaves the sliding surface 54 and snaps radially outwards, causing the retaining collar 48 of the clamping leg 46 to engage the cover 14 from behind. To prevent the conical body 52 of the actuating element 50, which is pressed against the clamping leg 46, from unnecessarily obstructing the flow cross-section of the fluid channel 32, at least one passage opening 56 can be provided in the actuating element 50, particularly in the conical body 52, to allow the forming gas to pass through more easily.

Claims

[1] Lid arrangement with a lid (14) for covering an opening in a housing (10) of a motor vehicle, wherein the lid (14) has a lid opening (16) for fluid-tight clipping of a pressure equalization element (20), and a forming gas adapter (26) inserted fluid-tight in the lid opening (16) for supplying a forming gas into a housing (10) of a motor vehicle, with a connection opening (34) for connecting a fluid line for forming gas, an outlet opening (36) for introducing the forming gas into the housing (10), a fluid channel (32) which communicates fluidically with the connection opening (34) and the outlet opening (36), a radially projecting mounting flange (28) from the fluid channel (32) for fluid-tight connection to a cover (14) that can be attached to the housing (10), at least one clamping leg (46) movably extending from the fluid channel (32) and passable through a lid opening (16) of the lid (14) for detachable fastening to the lid (14) and an actuating element (50) for adjusting the at least one clamping leg (46) between a mounting position in which the at least one clamping leg (46) can be passed through the cover opening (16) of the cover (14) and a holding position in which the at least one clamping leg (46) prevents a relative movement of the mounting flange (28) to the cover (14). [2] Lid arrangement according to claim 1, wherein the at least one clamping leg (46) is pivotally held on the fluid channel (32) in a manner that prevents loss. [3] Cover arrangement according to claim 1 or 2, wherein the actuating element (50) for adjusting the at least one clamping leg (46) in the fluid channel (32) is movable with a movement component in the axial direction of the fluid channel (32). [4] Lid arrangement according to one of claims 1 to 3, wherein the actuating body (50) has a conical body (52) for spreading the at least one clamping leg (46) into the holding position. [5] Lid arrangement according to one of claims 1 to 4, wherein the at least one clamping leg (46) has a retaining collar (48) for engaging behind the lid opening (16) of the lid (14) in the holding position and / or for pressing against a sliding surface (54) of the lid (14) in the holding position. [6] Cover arrangement according to one of claims 1 to 5, wherein the fluid channel (32) has a connection nozzle (40) for connecting a forming gas probe which communicates fluidically with the fluid channel (32). [7] Motor vehicle with a housing (10) wherein the housing (10) has a cover arrangement according to any one of claims 1 to 6. [8] Method for leak testing of a housing (10) of a motor vehicle, wherein a cover (14) attached to the housing (10) is removed, a pressure equalization element (20) inserted in a lid opening (16) of the lid (14) is removed, A forming gas adapter (26) intended for connecting a gas source is mounted fluid-tight and detachably in the lid opening (16), the cover (14) is attached to the housing (10) in a fluid-tight manner, a forming gas is introduced into the housing (10) via the forming gas adapter (26), It is checked whether there is a leakage of forming gas from the housing (10), the forming gas adapter (26) is removed from the lid opening (16) while the lid (14) remains attached to the housing (10), and the same or a different pressure equalization element (20) is fluid-tightly attached in the lid opening (16). [9] Method according to claim 8, wherein the method is carried out while the housing (10) is installed in a motor vehicle.