Battery system for a motor vehicle that is at least partially electrically powered and degassing valve

Abstract

Battery device (1) for a motor vehicle that is at least partially electrically powered, comprising a battery housing (2) with a housing space (12) for accommodating directly cooled battery cells (3) and with at least one housing wall (22) delimiting the housing space (12) with at least one housing degassing opening (32) for removing fluids from the housing space (12) and comprising at least one degassing valve (4) associated with the housing degassing opening (32) with at least one valve body (5), wherein the valve body (5) is axially adjustable from a sealing position (14) to a releasing position (24) against the force of a preloading device (7), and comprising at least one cooling device for directly cooling the battery cells (3) in the housing space (12) with a liquid coolant, wherein the coolant has direct contact with the battery cells (3) and with the degassing valve (4), characterized by that the valve body (5) has at least one radially circumferential sealing section (15) and that the degassing valve (4) comprises at least one base body (6) with at least one sealing surface (16) corresponding to the sealing section (15) of the valve body (5), such that the sealing section (15) can be radially enclosed by the sealing surface (16), and that the base body (6) of the degassing valve (4) has at least one connection section (44) which is arranged in a fluid-tight manner on a section of the housing wall (22) surrounding the housing degassing opening (32) and that the connection section (44) extends into the housing space (12) so that it can be acted upon by a pressure present in the housing space (12) against the housing wall (22).

Description

[0001] The present invention relates to a battery system for a motor vehicle that is at least partially electrically powered, comprising a battery housing and a degassing valve. The battery housing includes a housing chamber for accommodating, in particular, directly cooled battery cells and at least one housing wall delimiting the housing chamber, with at least one housing degassing opening for removing fluids from the housing chamber. At least one degassing valve is associated with the housing degassing opening.

[0002] These degassing valves allow pressure equalization between the inside of the battery housing and the surrounding environment. This may be necessary, for example, due to temperature fluctuations during charging or discharging of the battery cells, or due to changes in air pressure (e.g., when driving at higher altitudes).

[0003] Pressure equalization is particularly important in the event of a malfunction, such as a thermal runaway of the battery cells, which leads to the release of large quantities of hot gases. In such cases, the hot gases must be vented from the housing as quickly as possible via the degassing valves.

[0004] German patent DE 10 2019 007 454 A1 discloses an emergency venting system for an electric vehicle battery, in which a plate-shaped piston is pressed against a valve seat by means of a compression spring, thus tightly sealing the housing venting opening. By selectively choosing the springs, the opening pressure can be precisely determined in such solutions.

[0005] However, it is particularly difficult with batteries where the battery cells within the casing are directly surrounded by a (liquid) cooling medium (so-called direct cooling or directly cooled battery cells). In these cases, the degassing valves must not only equalize pressure but also ensure a reliable and permanent seal of the casing's degassing openings. This creates a conflict for the spring: its preload must precisely match the required opening pressure while simultaneously being large enough to press the piston firmly against the valve seat during normal operation.

[0006] Therefore, batteries have become known in which the casing's venting opening is sealed with a membrane, thus providing a reliable seal. At a specific pressure inside the casing, the membrane fails and releases the venting opening. However, it is sometimes difficult to manufacture and install the membrane in such a way that the desired opening pressure is precisely maintained.

[0007] From DE 10 2021 131 551 A1, a solution is known in which, if the pressure in the housing becomes too high, the diaphragm is moved against the spring action of a spring towards a mandrel and is pierced by the mandrel. Sealing during normal operation is thus achieved by the diaphragm. The opening pressure is adjusted by means of the spring.

[0008] A pressure compensation device for a coolant-flushed traction battery is known from DE 10 2021 115 321 A1. A movable, spring-loaded element is adjustable over a predetermined path when overpressure builds up inside the interior. The movable element has a predetermined breaking point that ruptures when a predetermined pressure difference is exceeded. This releases a vent. The adjustment movement of the movable element does not affect the release of the vent and serves to provide a compensation volume, e.g., to compensate for temperature increases caused by charging.

[0009] From DE 10 2015 214 256 A1, a pressure equalization device for compensating for internal pressure in a battery housing is known. The pressure equalization device comprises a valve body which, when the pressure exceeds a certain limit, moves from a rest position adjacent to a valve seat to a working position away from the valve seat. The valve body has a gas flow opening closed by means of a gas-permeable diaphragm.

[0010] US 2022 / 0069410A1 describes a pressure relief valve for an electric vehicle battery. The pressure relief valve is mounted on the outside of the battery housing and has a valve body that is axially displaceable within a radially circumferential sealing section.

[0011] CN 2 19 163 545 U and CN 2 19 267 750 U each show a lithium-ion battery with a pressure relief valve that can be positioned on the top of the battery cover adjacent to a battery terminal. The pressure relief valve has a valve body that is axially displaceable within a radially circumferential sealing section.

[0012] In contrast, the object of the present invention is to provide an improved method for pressure equalization. In particular, the solution should also be usable in battery systems with direct cooling. Furthermore, the solution should be easy to implement in terms of design and at the same time be able to seal reliably and securely.

[0013] This problem is solved by a battery device having the features of claim 1. A degassing valve according to the invention is the subject of claim 9. Preferred embodiments of the invention are the subject of the dependent claims. Further advantages and features of the present invention will become apparent from the general description and the description of the exemplary embodiment.

[0014] The battery system according to the invention is intended for a motor vehicle that is at least partially electrically powered, and preferably for a passenger car (electric vehicle or hybrid vehicle). The battery system comprises at least one battery housing with at least one housing compartment for accommodating directly cooled battery cells. The battery housing comprises at least one housing wall delimiting the housing compartment, with at least one housing vent opening, which serves in particular for draining fluids from the housing compartment or for pressure equalization. The battery system comprises at least one vent valve associated with the at least one housing vent opening. The vent valve comprises at least one valve body.

[0015] In particular, the valve body is axially adjustable from a sealing position to a release position against the force of a preloading device. The battery assembly includes at least one cooling device for directly cooling the battery cells in the housing with a liquid coolant. The coolant is in direct contact with the battery cells and the degassing valve. The valve body has at least one radially circumferential sealing section. The degassing valve comprises at least one base body with at least one sealing surface corresponding to the sealing section of the valve body. This allows the sealing section (at least in the sealing position and preferably also in the release position) to be radially enclosed by the sealing surface (thus achieving a sealing effect).The base body of the degassing valve has at least one connection section which is arranged in a fluid-tight manner on a section of the housing wall surrounding the housing degassing opening. The connection section extends into the housing chamber so that it can be subjected to pressure against the housing wall by pressure present in the housing chamber.

[0016] The present invention has many advantages. A significant advantage is offered by the sealing section of the valve body and the sealing surface of the base body, which together provide a radial seal. The radially circumferential sealing section and the corresponding sealing surface ensure that the force of the preload device, which adjusts the opening behavior for the degassing process, has no influence on the sealing effect of the degassing valve. This allows the opening behavior to be optimally adapted to the pressure conditions expected during operation. Furthermore, a secure and reliable seal is guaranteed even when only very low preload forces are present due to the desired opening behavior. Another advantage is that a decrease in preload force (for example, due to aging) or a reduction in preload force due to tolerances has no negative impact on the sealing effect.Furthermore, the degassing valve is stable over the long term and remains operational and leak-proof after pressure equalization, as no components are damaged when it is opened. Moreover, the invention presented here can be implemented with minimal structural complexity and is easy to assemble.

[0017] In particular, the pre-tensioning device pre-tensions the valve body in a direction of action. This direction of action is, in particular, transverse and preferably perpendicular to a sealing direction of action. In the sealing direction of action, the sealing section and the sealing surface are in contact with each other to achieve the sealing effect. In particular, the sealing section and the sealing surface are pressed together in the sealing direction of action. In particular, the direction of action is axial. In particular, the sealing direction of action is radial. In particular, the sealing section and the sealing surface form a radial seal or a radially acting sealing system. In particular, the direction of action and the sealing direction of action are not parallel.

[0018] In particular, the sealing section and the sealing surface are not aligned in the same direction of force or action as the pre-tensioning device. Specifically, the sealing section and the sealing surface are not pressed together by the pre-tensioning device. In particular, the sealing section and the sealing surface do not need to be pressed together by the pre-tensioning device to provide their sealing effect.

[0019] In particular, the sealing effect can also be provided when the sealing section and the sealing surface are in contact exclusively radially (and not additionally axially). However, it is possible for the sealing section and the sealing surface to also be in contact axially in the sealing position or in the end position of the valve body. This can be achieved, for example, by a suitably arranged sealing lip. This allows the sealing effect to be supported, if necessary, in the sense of redundancy. For the intended sealing effect, however, it is sufficient and advantageous in the present invention that the sealing section and the sealing surface are in contact radially.

[0020] In particular, the base body has at least one outlet opening through which fluids originating from the housing chamber can be discharged. In an advantageous embodiment, the at least one outlet opening is arranged at least partially within the sealing surface and / or at least partially in the axial direction behind the sealing surface (in a section of the base body). "Behind the sealing surface" here refers to the direction of movement of the valve body as it moves from the sealing position to the release position against the force of the preloading device.

[0021] In particular, the outlet opening is arranged between an axial end of the sealing surface facing the housing degassing opening and an axial end of the sealing surface facing away from the housing degassing opening. Additionally or alternatively, the at least one outlet opening can also be arranged on the end face of the base body. In particular, the outlet opening is provided by a recess in the base body. The recess can comprise a through-opening and / or a depression and, for example, a groove.

[0022] It is preferred and advantageous that the sealing section remains in contact with the sealing surface (sealing) even when the valve body has reached at least one of the at least one outlet opening, allowing fluids to escape from the outlet opening and / or the valve body is in the release position. In other words, the sealing section and sealing surface remain in contact according to the principle of a radial seal even when the fluids are discharged via the outlet opening. This enables a rapid and reliable return of the valve body to the sealing position once the pressure in the housing chamber has dropped again after degassing. For this purpose, the outlet opening is, in particular, arranged at least partially within the sealing surface. The sealing surface is, in particular, cylindrical or arranged on an inner wall (cylinder wall) of a hollow cylindrical section or cylinder element of the base body.

[0023] In an advantageous embodiment, the base body comprises a (tubular) cylindrical element. In particular, the sealing surface is arranged on a (radially) inner cylinder wall of the cylindrical element. It is preferred and advantageous that the valve body has a (cylindrical) piston element. In particular, the sealing section is arranged on a radial outer wall of the piston element. In particular, the piston element is axially movably mounted in the cylindrical element. In particular, the outlet opening is arranged in the cylinder wall. In particular, the piston element is disk-shaped and / or plate-shaped. In particular, the piston element and the cylindrical element abut each other in a radially sealing manner.

[0024] In an advantageous embodiment, the sealing section comprises at least one sealing element. In particular, the sealing element is attached to the valve body and preferably to the piston element. In particular, the sealing element is at least partially elastic. In particular, the sealing element is made of a sealing material, for example, rubber or plastic or the like. In particular, the sealing element is radially compressible against the sealing surface. This can be achieved, for example, by a corresponding oversize and / or by elastic material properties. It is possible that the sealing element forms the sealing section. In this case, the terms sealing section and sealing element can be used synonymously within the scope of the present invention.

[0025] The sealing device is, in particular, annular in shape. In particular, the sealing device surrounds the piston element in the circumferential direction. The sealing device comprises, in particular, at least one sealing ring or is designed as such. In particular, the sealing device moves together with the valve body. Additionally or alternatively, the base body can have at least one sealing unit attached to the sealing surface. In particular, the sealing unit is elastically designed. In particular, the sealing unit surrounds the sealing section in the circumferential direction.

[0026] It is possible and advantageous for the sealing device to have at least one pocket structure. In particular, the pocket structure (with respect to its opening) faces the housing venting opening. The pocket structure is especially suitable and designed so that the sealing device is pressed against the sealing surface when the pocket structure is subjected to pressure present in the housing. This further improves the sealing effect.

[0027] In an advantageous embodiment, the sealing device, in combination with the sealing surface, provides a linear guide for the movement of the valve body within the base body. In particular, the movement of the valve body is guided axially, i.e., in the direction of the preload. This enables a particularly reliable return of the valve body to its original position. As a result, the degassing valve is reliably sealed again after a degassing process and can be reused. Additionally or alternatively, the sealing unit, in combination with the sealing section, can provide a linear guide.

[0028] According to the invention, the base body of the degassing valve has at least one connection section. According to the invention, the connection section is arranged in a fluid-tight manner on a section of the housing wall surrounding the housing degassing opening. In particular, the connection section is part of the base body or attached to it. According to the invention, the connection section extends into the housing chamber so that the connection section can be subjected to pressure against the housing wall by pressure present in the housing chamber. The connection section can include at least one sealing element and, for example, an O-ring or the like.

[0029] The degassing valve according to the invention is suitable and designed for use in the battery device according to the invention or one of its embodiments. In particular, the degassing valve is designed as described in the context of the battery device according to the invention. The degassing valve also solves the previously stated problem particularly advantageously.

[0030] The battery assembly comprises at least one cooling device for cooling the battery cells in the housing with a liquid coolant. According to the invention, the cooling device enables direct cooling of the battery cells in the housing. According to the invention, the coolant has direct contact with the battery cells and the degassing valve. In particular, the housing provides part of a coolant circuit.

[0031] In the sealed position, the housing vent opening is closed by the vent valve, particularly in a fluid-tight manner (preferably also with respect to any liquid coolant located in the housing chamber). In the released position, fluids can escape from the housing chamber through the housing vent opening and the vent valve. The preloading device holds the valve body, particularly in the sealed position. Specifically, the valve body can be moved axially multiple times within the base body, allowing the vent valve to be opened and closed repeatedly.

[0032] The preloading device comprises, in particular, at least one spring and / or another suitable preloading means. The spring is, for example, a compression spring, tension spring, gas spring, metallic spring, or the like. The base body may have at least one support section for supporting the preloading device. The support section may be provided by a closed axial end.

[0033] The degassing valve serves primarily for pressure equalization during normal operation and / or for the removal of gases in the event of thermal runaway of the battery cell or another corresponding malfunction. The degassing valve is specifically designed so that the outlet remains closed even during axial movement of the valve body (for example, due to a decrease in the force of the preloading device). For this purpose, the axial length of the sealing section and sealing surface, as well as the position of the outlet, are designed and arranged accordingly.

[0034] In particular, the sealing section and the sealing surface are arranged coaxially, at least in the sealing position (preferably also in the release position). The coaxial arrangement is also present, in particular, when the valve body is axially displaced against the force of the preloading device. The sealing position extends, in particular, over the axial length of the sealing section and / or the sealing surface. The sealing position extends, in particular, until the sealing section and the sealing surface are no longer arranged adjacent to each other in the radial direction and / or until the sealing section has been displaced axially to such an extent that it is located behind the outlet opening of the base body.

[0035] In particular, the degassing valve only opens when a minimum travel distance of the valve body is exceeded. With known degassing valves, the sealing effect is immediately lost due to technical reasons as soon as the valve body moves axially. The minimum travel distance is, in particular, the distance between the valve body in the intended sealing position or in its end position and the outlet opening. For example, the minimum travel distance is at least 1 mm and preferably at least two, three, four, or even five millimeters. The minimum travel distance can also be at least 8 mm, ten, or twelve millimeters. A minimum travel distance of at least two, three, or four centimeters is also possible. In particular, the minimum travel distance is dimensioned taking into account the sealing effect and the pressure conditions expected during operation. Specifically, the sealing position extends over the minimum travel distance.

[0036] Further advantages and features of the present invention will become apparent from the exemplary embodiments, which are explained below with reference to the accompanying figures.

[0037] The figures show: Fig. 1 a purely schematic representation of a battery device according to the invention in a sectional view; Fig. 2 a detailed representation of the battery system of the Fig. 1 with a valve body in a sealing position; and Fig. 3 a detailed representation of the battery system of the Fig. 1 with a valve body in a release position.

[0038] The Fig. Figure 1 shows a battery device 1 according to the invention with a battery housing 2, which is shown here purely by way of example as the housing of a battery module. The battery device 1 can comprise further battery modules, not shown here, or be provided by a single battery module. The battery device 1 is, for example, a high-voltage battery or traction battery for powering a motor vehicle that is at least partially electrically driven.

[0039] The housing compartment 12 of the battery housing 2 contains a large number of battery cells 3 (of which only one is shown here as an example). The housing compartment 12 is part of a coolant circuit of a cooling device, so that the battery cells 3 are directly surrounded by a liquid cooling medium.

[0040] In a housing wall 22 that delimits the housing space 12, housing degassing openings 32 are arranged, which serve for pressure equalization and for the discharge of hot gases or liquids in the event of thermal runaway of the battery cells 3. For clarity, only one housing degassing opening 32 is shown here.

[0041] To seal the housing chamber 12 from the environment during normal operation, the housing degassing openings 32 are each closed by a coolant-tight degassing valve 4. The degassing valve 4 is described below with reference to the detailed illustrations of the Fig. 2 and Fig. 3 described in more detail.

[0042] The degassing valve 4 has a valve body 5 and a base body 6. The valve body 5 is axially movable within the base body 6. The valve body 5 consists of a sealing element 14, which is located in the Fig. 2 is shown, in a release position 24, which is in the Fig. As shown in Figure 3, the housing is axially adjustable against the force of a preloading device 7. In the sealing position 14, the housing degassing openings 32 are fluid-tight. In the release position 24, the hot gases can escape from the housing chamber 12 via outlet openings 26 and the pressure can be relieved.

[0043] The base body 6 comprises a tubular cylinder element 36, on the inner cylinder wall of which a sealing surface 16 is arranged. The valve body 5 has a cylindrical piston element 25, on the radial outer wall of which a sealing section 15 is arranged. The outlet openings 26 are distributed around the circumference of the cylinder wall.

[0044] The preload device 7 includes, for example, a spring 17. The spring 17 rests on a support section 46 and presses the valve body 5 towards the housing vent opening 32 against the housing wall 22. When the internal pressure rises above the intended opening pressure, the spring 17 is compressed until the vent valve 4 opens and the excess pressure can escape. After the internal pressure falls below the opening pressure again, the spring 17 pushes the valve body 5 back into its end position and the vent valve 4 seals again.

[0045] The sealing section 15 is radially circumferential and is provided here by a sealing device 8. The sealing device 8 comprises, for example, one or more sealing rings 28. The sealing surface 16 corresponds to the sealing section 15 and is arranged coaxially to the valve body 5, so that it radially surrounds it.

[0046] The sealing section 15 and the sealing surface 16 abut each other radially, creating a sealing effect. This provides a radial seal, the sealing direction 34 of which is indicated here by a dashed double arrow. The direction of action 27 of the preloading device 7 is also indicated here by a dashed double arrow. It is clearly visible that the sealing direction 34 and the direction of action 27 are arranged transversely and not parallel to each other. This allows the opening behavior of the degassing valve 4 to be adjusted independently of the sealing effect between the valve body 5 and the base body 6. In other words, the preload force of the preloading device 7 has no influence on the desired sealing effect.

[0047] As in the Fig. As can be clearly seen in Figure 3, the sealing section 15 still seals against the sealing surface 16 even when the pressure inside the housing (shown here by block arrows) is so great that it has already pushed the valve body 5 back so far that the outlet opening 26 is exposed.

[0048] The sealing device 8, together with the sealing surface 16, forms a linear guide for the valve body 5 relative to the base body 6. This allows the valve body 5 to be moved smoothly and without tilting back into the sealing position 14 after pressure equalization by means of the preload device 7.

[0049] In an advantageous embodiment, the base body 6 can have a connection section 44 (in the Fig.(2 shown with dashed lines). The connecting section 44 rests against an inner surface of the housing wall 22, so that it is pressed against the housing wall 22 by the internal pressure. This ensures a particularly reliable seal between the battery housing 2 and the degassing valve 4.

[0050] The sealing device 8 can be equipped with a pocket structure 18 in a variant not shown in detail here. The pocket structure 18, or rather its opening, faces the housing venting opening 32. This allows the sealing device 8 to be pressed more firmly against the sealing surface 16 when the pocket structure 18 is subjected to the internal pressure of the battery housing 2. Reference symbol list: 1 Battery unit 2 battery cases 3 battery cells 4 Degassing valve 5 valve bodies 6 basic bodies 7 Pre-tensioning device 8 Sealing device 12 Housing space 14 Sealing position 15 Sealing section 16 sealing surface 17 spring 18-pocket structure 22 Housing wall 24 Release position 25 piston element 26 Exit opening 27 Direction of action 28 sealing rings 32 Housing degassing opening 34 Sealing direction 36 Cylinder element 44 Connection section 46 Support section

Claims

[1] Battery device (1) for a motor vehicle that is at least partially electrically powered, comprising a battery housing (2) with a housing space (12) for accommodating directly cooled battery cells (3) and with at least one housing wall (22) delimiting the housing space (12) with at least one housing degassing opening (32) for removing fluids from the housing space (12) and comprising at least one degassing valve (4) associated with the housing degassing opening (32) with at least one valve body (5), wherein the valve body (5) is axially adjustable from a sealing position (14) to a releasing position (24) against the force of a preloading device (7), and comprising at least one cooling device for directly cooling the battery cells (3) in the housing space (12) with a liquid coolant, wherein the coolant has direct contact with the battery cells (3) and with the degassing valve (4), characterized by , that the valve body (5) has at least one radially circumferential sealing section (15) and that the degassing valve (4) comprises at least one base body (6) with at least one sealing surface (16) corresponding to the sealing section (15) of the valve body (5), such that the sealing section (15) can be radially enclosed by the sealing surface (16), and that the base body (6) of the degassing valve (4) has at least one connection section (44) which is arranged in a fluid-tight manner on a section of the housing wall (22) surrounding the housing degassing opening (32) and that the connection section (44) extends into the housing space (12) so that it can be acted upon by a pressure present in the housing space (12) against the housing wall (22). [2] Battery device (1) according to the preceding claim, wherein the preloading device (7) preloads the valve body (5) in an effective direction (27) and wherein the effective direction (27) is arranged transversely and in particular perpendicularly to a sealing effective direction (34) in which the sealing section (15) and sealing surface (16) are in contact with each other to achieve the sealing effect. [3] Battery device (1) according to one of the preceding claims, wherein the base body (6) has at least one outlet opening (26) through which fluids originating from the housing space (12) can be discharged, and wherein the outlet opening (26) is arranged at least partially within the sealing surface (16) and / or at least partially in the axial direction behind the sealing surface (16). [4] Battery device (1) according to the preceding claim, wherein the sealing section (15) still rests against the sealing surface (16) even when the valve body (5) has reached the outlet opening (26) and fluids can escape from the outlet opening (26). [5] Battery device (1) according to one of the preceding claims, wherein the base body (6) has a cylinder element (36) on the inner cylinder wall of which the sealing surface (16) is arranged, and wherein the valve body (5) has a piston element (25) on the radial outer wall of which the sealing section (15) is arranged and which is axially movable in the cylinder element (36). [6] Battery device (1) according to one of the preceding claims, wherein the sealing section (15) has at least one sealing device (8). [7] Battery device (1) according to the preceding claim, wherein the sealing device (8) has at least one pocket structure (18) facing the housing degassing opening (32) such that the sealing device (8) is pressed against the sealing surface (16) when the pocket structure (18) is subjected to a pressure present in the housing space (12). [8] Battery device (1) according to one of the two preceding claims, wherein the sealing device (8) in combination with the sealing surface (16) provides a linear guide for the movement of the valve body (5) in the base body (6). [9] Degassing valve (4) for a battery device (1) according to one of the preceding claims.

Images