Device for pressure equalization in a housing

Abstract

Device (100) for equalizing the internal pressure of a housing, in particular a battery housing for a motor vehicle, with the ambient pressure of the housing, wherein the device (100) has a pressure equalization element (10), wherein the pressure equalization element (10) comprises at least one element body (11) and a membrane (12) arranged on the element body (11), wherein the device (100) comprises a connecting element (13) for airtight connection of the pressure equalization element (10) to the housing, characterized in that the element body (11) has an elasticity by virtue of which, when an internal pressure is lower than a limit pressure, the element body (11) rests airtight on the connecting element (13) and, when an internal pressure is greater than the limit pressure, the element body (11) releases an opening between the element body (11) and the connecting element (13) for gas exchange.

Description

[0001] The invention relates to a device for equalizing the internal pressure of a housing, in particular a battery housing of a motor vehicle, with the ambient pressure of the housing. Furthermore, the invention relates to a battery, in particular a high-voltage battery for a motor vehicle, comprising the device for equalizing the internal pressure of a housing with the ambient pressure of the housing. State of the art

[0002] In the housings of high-voltage battery systems, particularly in motor vehicles, temperature and pressure changes cause pressure differences between the battery system housing and the surrounding environment. These differences must be equalized during normal operation. Furthermore, especially with high-capacity high-voltage battery systems, there is a risk that one or more cells will fail due to overload or other technical defects. This can result in the release of large quantities of harmful gases, which must be vented in a controlled manner. This is particularly important if the battery system is located near air conditioning intakes or openings to the vehicle's interior.

[0003] Currently, the two functions – pressure equalization during normal operation and emergency degassing – are usually handled by two separate solutions. For example, microfilters are used for pressure equalization during normal operation, while rupture discs are used for emergency degassing.

[0004] These types of individual solutions typically comprise at least two components. This results in high costs due to complex manufacturing or assembly processes. Furthermore, these systems usually require a large amount of installation space.

[0005] From DE 10 2014 111 041 A1, a degassing valve for degassing a housing, in particular a housing for a motor vehicle battery, is known. The degassing valve comprises a membrane that is watertight but breathable. A tensioning frame presses the membrane against a support element with a predetermined contact force. The contact force is less than a release force at which the membrane detaches from the support element and opens a fluid channel between an interior of the housing and the surrounding environment.

[0006] From DE 10 2017 003 360 B3 a pressure equalization device for a housing is also known, wherein the pressure equalization device comprises an inner side, an outer side and a grid-shaped cage with a gas passage opening, wherein the gas passage opening connects the inner side and the outer side in a flow-conducting manner as required and is limited in the direction of its flowability by an inner and an outer edge. Description of the invention: Problem, solution, advantages

[0007] The invention is based on the objective of providing a device for equalizing the internal pressure of a housing, in particular a battery housing for a motor vehicle, with the ambient pressure of the housing, which integrates the functions of pressure equalization during normal operation and emergency venting in a single component. This objective is achieved by the features specified in claim 1.

[0008] The device for equalizing the internal pressure of a housing, in particular a battery housing for a motor vehicle, with the ambient pressure of the housing, comprises a pressure equalization element which includes at least one element body and a membrane arranged on the element body. The pressure equalization element can be connected airtight to the housing by means of a connecting element. The element body exhibits elasticity, which, when the internal pressure is lower than a limit pressure, causes the element body to rest airtight against the connecting element. If the internal pressure is higher than the limit pressure, the element body opens an opening between the element body and the connecting element to allow gas exchange.

[0009] The membrane is preferably arranged on the pressure equalization element in such a way that pressure equalization can occur via the membrane during normal operation. For this purpose, the membrane allows the exchange of small amounts of air between the interior of the housing and the surrounding environment. Furthermore, the membrane is slightly elastic to reduce the pressure inside the housing by increasing its volume. Preferably, the membrane is impermeable to liquids to prevent the ingress of water or moisture into the battery housing.

[0010] Emergency venting is necessary if the limit pressure is exceeded. The limit pressure is therefore the pressure that occurs when a critical amount of harmful gas has been generated inside the battery casing. To allow the harmful gas to be vented after the limit pressure is exceeded, the element body exhibits elasticity. Upon reaching the limit pressure, this elasticity causes the element body to deform, preferably in a direction away from the battery casing and away from the connecting element, thus creating an opening between the element body and the connecting element. Harmful gas can then be vented to the environment through this opening.

[0011] During normal operation, pressure equalization via the diaphragm allows for pressure equalization in both directions, i.e., from the inside of the housing to the environment or from the environment into the inside of the housing. Emergency degassing, however, can only occur in one direction, i.e., from the inside of the housing to the environment. For this purpose, the element body rests on the connecting element in such a way that it forms a kind of valve.

[0012] Advantageous embodiments of the invention are characterized in the dependent claims.

[0013] In an advantageous embodiment, the element body has a particularly circular edge, which is formed in the form of at least one sealing lip. If the internal pressure of the housing is lower than the limit pressure, the sealing lip rests on a surface of the connecting element facing away from the housing, particularly on the underside.

[0014] If the limit pressure inside the housing is exceeded, an opening is created between the at least one sealing lip and the connecting element to vent any resulting quantities of harmful gases. This occurs when the pressure equalization element deforms elastically, causing it to lift away from the connecting element. Preferably, a second sealing lip is provided, which is arranged radially offset from the first sealing lip.

[0015] The sealing lip runs along the entire circumference of the circular edge and seals the area between the pressure equalization element and the connecting element airtight when the limit pressure is not exceeded. Only when the limit pressure inside the housing is exceeded does the sealing lip either partially or completely lift away from the surface of the connecting element facing away from the housing.

[0016] Furthermore, the connecting element has a ring-shaped, radially projecting surface, which is preferably designed such that a connection device of a leak testing apparatus can be attached to this surface. For this purpose, the surface is particularly large in the radial direction.

[0017] According to a further advantageous embodiment, the pressure equalization element is provided with a pin for attaching the pressure equalization element to the connecting element. The pin is preferably arranged on the element body and is oriented with its longitudinal axis perpendicular to the surface of the housing.

[0018] Advantageously, the pin has at least one locking element which can engage with a recess, projection, or edge on the connecting element. Particularly preferably, the locking element extends completely around the circumference of the pin so that it can engage with an annular receptacle on the connecting element.

[0019] The snap-in element allows for particularly easy mounting of the pressure equalization element to the connecting element. However, in addition to the snap-in connection, any other suitable connection type is also possible for linking the pressure equalization element to the connecting element. In particular, the connection between the pressure equalization element and the connecting element is detachable to allow for easy replacement of the pressure equalization element.

[0020] Replacing the pressure equalization element is only advantageous if it is damaged. However, this is only necessary, for example, after a strong external force, since no irreparable damage occurs to the device during normal operation or after emergency degassing. Therefore, replacement of the device is not necessary, particularly after emergency degassing.

[0021] According to a further advantageous embodiment, the membrane is integrated into the element body and partially enclosed by it. The membrane is preferably annular in shape. Alternatively, the membrane may also be composed of several partial membranes. Preferably, the membrane is made of polytetrafluoroethylene (PTFE).

[0022] According to a further advantageous embodiment, the element body has at least one recess which is covered by at least one membrane. Pressure equalization preferably occurs via this recess during normal operation, i.e., when the pressure difference between the interior of the housing and the environment is small, by allowing the exchange of small quantities of air through the membrane stretched over the recess.

[0023] Advantageously, the element body has several recesses, which are bordered by ribs. These numerous recesses are advantageously arranged in a ring shape so that they are covered by the ring-shaped membrane integrated into the element body. The recesses can be of identical size or, alternatively, of different sizes.

[0024] According to a further advantageous embodiment, the membrane is connected to the element body by means of an injection molding or casting process and is thus integrated into it. However, other joining techniques are also conceivable that enable a firm and airtight connection between the membrane and the element body.

[0025] According to an advantageous embodiment, the element body comprises an elastomer, preferably EPDM (ethylene propylene diene monomer rubber). This gives the element body the property of deforming when a limit pressure is exceeded, thus creating an opening for the venting of pollutant gas or other gases between the connecting element and the pressure equalization element. The elasticity is selected according to the desired limit pressure.

[0026] During emergency degassing, when the pressure inside the housing exceeds the limit pressure, the pin preferably remains fixed in position due to the snap-fit ​​connection with the connecting element. Therefore, no translational movement of the pressure equalization element away from the housing occurs. The element body deforms, particularly in its edge region, in such a way that gas can escape between the pressure equalization element (or the element body) and the connecting element.

[0027] During the manufacturing process of the pressure equalization element, the membrane is placed in a suitable tool, such as an injection mold, a casting mold, or a vulcanizing tool, and clamped by punches. The contact surface between the punches and the membrane is thereby masked, with the contact surfaces forming or corresponding to the recesses. The mold into which the membrane is placed corresponds to the shape of the element body.

[0028] The EPDM is then filled into the mold. This filling process preferably takes place under high pressure, so that the elastomer is forced into the protruding membrane sections not covered by the dies. In this process, the elastomer is pressed into the porous surface of the membrane, creating a mechanically robust and airtight bond between the elastomer (or the element body) and the membrane. The connection between the membrane and the element body is therefore essentially achieved through positive locking.

[0029] To further increase the positive fit and thus the mechanical strength between the membrane and the element body, the edge can preferably be provided with holes which are additionally filled with the elastomer during the injection or casting process.

[0030] Furthermore, it is advantageous to reinforce the element body by means of plastic or metal inserts. These inserts are preferably also placed in the mold of the injection or casting tool.

[0031] Furthermore, the invention relates to a battery, in particular a high-voltage battery for a motor vehicle, comprising a device with the features described above. Brief description of the drawings

[0032] An embodiment of the invention is explained in more detail below with reference to the drawings. They show a schematic representation. Fig. 1 an exploded view of the pressure equalization device, Fig. 2 a cross-sectional view of the pressure equalization element, Fig. 3 a view of the device from a side facing the interior of the housing, and Fig. 4 a cross-sectional view of the device.

[0033] In Fig. Figure 1 shows an exploded view of the device 100 for equalizing the internal pressure of a housing with the ambient pressure of the housing. The housing can, for example, be the housing of a high-voltage battery of a motor vehicle. The device 100 has a cover 200 on the side facing away from the housing (not shown in the figures), which protects the device from the ingress of moisture and dirt. At the same time, however, the cover has openings to allow gas exchange for pressure equalization during normal operation and during emergency degassing.

[0034] The pressure equalization element 10 is arranged below the cover 200. The pressure equalization element 10 has an element body 11 with a disc-like basic shape. Several recesses 11a are arranged within the disc-like basic shape of the element body 11. The recesses 11a are arranged in the element body 11 such that they are separated from each other by narrow webs and form a ring-like structure.

[0035] The membrane 12 extends into the ring-shaped recesses 11a. The pressure equalization element 10 is preferably manufactured using an injection molding or casting process. In this process, the membrane 12 is overmolded with the elastomer that forms the element body 11, such that the ring-shaped membrane 12 is exposed at the recesses 11a and otherwise enclosed by the element body 11.

[0036] The pressure equalization element 10 can be connected to the housing by means of a pin 16 and the connecting element 13 arranged between the housing and the pressure equalization element 10. For this purpose, the pin 16 has a circumferential locking element 16a on its circumferential surface, which can be engaged with an annular counterpart.

[0037] The connecting element 13 has a circular rim formed by an annular surface 15. The annular surface 15 is sufficiently large in the radial direction to allow an adapter of a leak testing device to be attached to it. Furthermore, the connecting element has a sleeve comprising a device for fastening the cover 200. This device can, for example, be a thread and a locking mechanism in the form of a groove into which the cover 200 can be screwed or snapped.

[0038] To ensure an airtight connection between the connecting element 13 and the housing, a seal 300, preferably an O-ring, is arranged in an annular groove on the underside of the connecting element 13 between the connecting element 13 and the housing. The connecting element 13 can be connected to the housing in an airtight and watertight manner, for example, by gluing or welding. The surface of the annular area 15 facing the housing on the side of the connecting element 13 preferably serves as the bonding or welding surface.

[0039] In Fig. Figure 2 shows a cross-sectional view of the pressure equalization element 10. In cross-sectional view, the element body 11 essentially has a T-shape. The element body 11 comprises two sealing lips 14a, 14b, which are arranged on an edge region 14 of the element body 11, as well as the pin 16 and the locking element 16a arranged on the pin. The element body 11, the sealing lips 14a, the pin 16, and the locking element 16a are preferably formed in one piece.

[0040] The two sealing lips 14a, 14b are arranged one behind the other in the radial direction and increase the tightness of the device in cases where the limit pressure in the housing is not exceeded and no emergency degassing occurs. Alternatively, only one sealing lip 14a, 14b or more than two sealing lips 14a, 14b can be provided.

[0041] The pin 16 is arranged with its longitudinal axis perpendicular to the membrane 12 and has the locking element 16a approximately in the middle, which runs along the circumferential surface of the pin 16 and tapers axially towards the end of the pin. This forms a kind of barb on the pin, which can be firmly inserted into a corresponding ring-shaped counterpart on the connecting element 13.

[0042] Fig. Figure 3 shows the device 100 from a side facing the interior of the housing. The underside of the connecting element 13 with the annular groove in which the seal 300, in the form of an O-ring, is arranged is visible. The pressure equalization element 10 with the pin 16 is also shown; the pin is connected to the annular counterpart, which forms an edge, by means of the locking element 16a. The locking mechanism formed by the locking element 16a and the edge of the annular counterpart allows the pressure equalization device to be easily mounted on the connecting element 13, particularly without the use of tools.

[0043] For this purpose, the pin 16 with the locking element 16a is pressed through the annular counterpart on the connecting element until the locking element 16a engages behind the edge. In this state, the sealing lips 14a, 14b also rest on the side of the connecting element 13 facing away from the housing, thus forming a counter-pressure, whereby the pressure equalization element 10 is airtightly connected to the connecting element 13, except for the area of ​​the diaphragm 12.

[0044] Fig.Figure 4 shows the device 100, comprising the cover 200, the pressure equalization element 10, the connecting element 13, and the seal 300, in a cross-sectional view in its assembled state. In this state, the device 100 is in its normal operating position, with the sealing lips 14a and 14b resting on the connecting element 1. The cover 200 is connected to the sleeve-like section of the connecting element 13 by means of a locking mechanism. Both the sleeve-like section and the cover 200 have openings for the exchange of gas and air, respectively. Reference symbol list 100 Device 10 pressure equalization element 11 Element bodies 11a Recess 12 Membran 13 Connecting element 14 Rand 14a,b Sealing lip 15 ring-shaped area 16 cones 16a Latching element 200 lids 300 seals

Claims

[1] Device (100) for equalizing an internal pressure of a housing, in particular a battery housing for a motor vehicle, with an ambient pressure of the housing, wherein the device (100) has a pressure equalization element (10), wherein the pressure equalization element (10) comprises at least one element body (11) and a membrane (12) arranged on the element body (11), wherein the device (100) comprises a connecting element (13) for airtight connection of the pressure equalization element (10) to the housing, characterized by , that the element body (11) has an elasticity which, when there is an internal pressure which is less than a limit pressure, the element body (11) rests airtight on the connecting element (13) and when there is an internal pressure which is greater than the limit pressure, the element body (11) releases an opening between the element body (11) and the connecting element (13) for the exchange of gas. [2] Device (100) according to claim 1, wherein the element body (11) has a particularly circular edge (14) which is formed in the form of at least one sealing lip (14a, 14b), wherein the sealing lip (14a, 14b) rests in the edge region, in particular on the underside of the connecting element (13), when an internal pressure is present which is less than the limit pressure. [3] Device (100) according to claim 1 or 2, wherein the pressure equalization element (10) has a pin (16) for attaching the pressure equalization element (10) to the connecting element (13). [4] Device (100) according to claim 3, wherein the pin (16) has at least one locking element (16a) which can engage with a recess, projection or edge present on the connecting element (13). [5] Device (100) according to one of the preceding claims, wherein the membrane (12) is partially enclosed by the element body (11). [6] Device (100) according to one of the preceding claims, wherein the element body (11) has at least one recess (11a) which is covered by the at least one membrane (12). [7] Device (100) according to one of the preceding claims, wherein the membrane (12) is connected to the element body by means of an injection molding or casting process. [8] Device (100) according to one of the preceding claims, wherein the element body (11) comprises an elastomer, preferably EPDM (ethylene propylene diene monomer rubber). [9] Battery, in particular a high-voltage battery for a motor vehicle, comprising a device (100) according to one of the preceding claims.

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