Emergency degassing valve for a battery housing of a high-voltage battery, battery housing, high-voltage battery and motor vehicle

Abstract

Emergency degassing valve (1) for a battery housing of a high-voltage battery for releasing hot gas from an interior (3) of the battery housing, comprising: - a valve seat (5) for attachment to the battery housing and for forming a flow channel (9) for the hot gas between the interior (3) and an environment (4) of the battery housing, - a valve body (10) for closing the flow channel (9), characterized by the fact that the emergency degassing valve (1) is designed as a spring-loaded full-stroke safety valve and has a spring clamping unit (14) arranged on the valve seat (5), which - designed to provide a closed state of the emergency degassing valve (1) by exerting a spring force directed obliquely to a flow direction (S) of the hot gas on the valve body (10) to provide a force-fit connection between the valve seat (5) and the valve body (10), and - designed to provide an open state of the emergency degassing valve (1) to interrupt the force-locking connection when an internal pressure corresponding to a predetermined response pressure acts on the valve body (10) due to hot gas and to permanently remove the valve body (10) from the valve seat (5) while releasing the complete flow channel (9).

Description

[0001] The invention relates to an emergency venting valve for a battery housing of a high-voltage battery for discharging a hot gas from an interior of the battery housing. The emergency venting valve comprises a valve seat for attachment to the battery housing and for forming a flow channel for the hot gas between the interior and an area surrounding the battery housing, and a valve body for closing the flow channel. The invention also relates to a battery housing, a high-voltage battery, and a motor vehicle.

[0002] In the present case, interest is focused on rechargeable high-voltage batteries or electrical energy storage devices, which can be used, for example, as traction batteries in electrically powered motor vehicles. Such high-voltage batteries typically have a battery housing, within the interior of which a plurality of interconnected battery cells, for example lithium-ion battery cells, are arranged. In the event of a fault, for example, in the event of an internal cell short circuit, such battery cells can produce a hot gas that escapes from a cell housing of the battery cells into the interior of the battery housing. This hot gas leads to an increase in internal pressure in the interior of the usually gas-tight battery housing and, above a predetermined overpressure threshold, must be released into the environment of the battery housing to prevent thermal runaway of the high-voltage battery.

[0003] To release the hot gas, also known as emergency venting, so-called bursting membranes are known from the prior art. These open an emergency venting opening in the battery casing at a predetermined set pressure corresponding to the overpressure threshold. Such bursting membranes exhibit design- and manufacturing-related fluctuations in their set pressure. This fluctuating set pressure can lead to the emergency venting being performed at the wrong time, thereby damaging the battery casing. Additional safety precautions to prevent false triggering of the bursting membranes are often material-intensive and cost-intensive.

[0004] Pressure equalization units for battery housings that feature check valves are also known from the prior art, for example, DE 10 2013 213 909 A1. These check valves have the disadvantage that the flow cross-section of a flow channel for the hot gas, which runs between the interior and the surroundings of the battery housing, is limited by the check valve and thus cannot be fully utilized. Therefore, a larger flow cross-section must be provided, which in turn has a negative impact on costs and installation space.

[0005] It is an object of the present invention to provide a cost-effective and space-saving solution for carrying out emergency degassing of a high-voltage battery, which also has a precise response pressure.

[0006] This object is achieved according to the invention by an emergency venting valve, a battery housing, a high-voltage battery, and a motor vehicle having the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0007] An emergency venting valve according to the invention for a battery housing of a high-voltage battery serves to release a hot gas from an interior of the battery housing. The emergency venting valve has a valve seat for attachment to the battery housing. The valve seat forms a flow channel for the hot gas between the interior and an area surrounding the battery housing. Furthermore, the emergency venting valve has a valve body for closing the flow channel. The emergency venting valve is designed as a spring-loaded full-stroke safety valve and has a spring clamp unit arranged on the valve seat. The spring clamp unit is designed to provide a closed state of the emergency venting valve by exerting a spring force on the valve body that is directed obliquely to a flow direction of the hot gas, creating a force-locking connection between the valve seat and the valve body.To provide an open state of the emergency degassing valve, the spring clamp unit is designed to interrupt the force-locking connection when an internal pressure acting on the valve body due to hot gas and corresponding to a predetermined response pressure occurs, wherein the internal pressure and the interrupted force-locking connection allow the valve body to be permanently removed from the valve seat, releasing the entire flow channel.

[0008] The invention also includes a battery housing for a high-voltage battery, comprising a plurality of housing walls enclosing an interior space for accommodating battery cells of the high-voltage battery, and comprising an emergency venting valve according to the invention, wherein the emergency venting valve is arranged in one of the housing walls. A high-voltage battery according to the invention comprises a battery housing according to the invention and a plurality of battery cells arranged in the interior space of the battery housing.

[0009] The high-voltage battery can be used as a traction battery for providing drive power for an electric drive of an electrically powered motor vehicle. The high-voltage battery has a plurality of battery cells, for example lithium-ion cells, which are arranged in the interior of the battery housing. The battery housing can have housing walls in the form of a housing base, a housing cover, and housing side walls that delimit the interior. In the event of a fault, for example, a cell-internal short circuit, the battery cells can release a hot gas into the interior of the battery housing, which causes the internal pressure in the interior of the battery housing to rise. An increase in the internal pressure above a predetermined overpressure threshold could lead to thermal runaway and, subsequently, a fire in the high-voltage battery.

[0010] Therefore, at least one of the housing walls has an emergency venting opening with the emergency venting valve. The valve seat of the emergency venting valve is arranged in the emergency venting opening. The valve seat is preferably designed as a tube. During normal operation of the high-voltage battery, i.e. as long as the internal pressure falls below the predetermined overpressure threshold, the valve seat and thus the entire battery housing are sealed tightly, in particular gas-tight, by the valve body or shut-off body of the emergency venting valve. The valve body is designed in particular as a spherical body. In the event of emergency venting, i.e. as soon as the internal pressure has reached the overpressure threshold due to hot gas, the valve body opens the valve seat and thus the flow channel formed by the valve seat, so that the hot gas emitted by the battery cell(s) can escape from the interior via the flow channel into the environment to reduce the excess pressure.The emergency venting valve is triggered at an internal pressure value that corresponds to the overpressure threshold. This internal pressure value corresponds to the trigger pressure or response pressure of the emergency venting valve.

[0011] The emergency venting valve is a spring-loaded full-stroke safety valve or spring-loaded full-stroke pressure relief valve, which opens abruptly and with full stroke at the adjustable set pressure. In the context of the invention, this means that the valve body is abruptly removed from the valve seat at the set pressure, which corresponds to the predetermined overpressure threshold, thereby exposing the entire flow channel. This provides the hot gas with access to the entire flow cross-section of the flow channel as it escapes from the interior. The hot gas can thus quickly escape from the interior of the battery housing via the opened flow channel.

[0012] During normal operation, the valve body is held in the valve seat by the spring clamp unit, which exerts a spring force on the valve body, which holds the valve body in the valve seat up to the set pressure. The spring force acts obliquely, in particular transversely or perpendicularly, to the direction of flow. The valve body is designed such that it is set in motion by the internal pressure caused by the hot gas and can exert a force on the spring clamp unit that is opposite to the spring force. As soon as the internal pressure caused by the hot gas has reached the set pressure, the opposing force also exceeds the spring force of the spring clamp unit, and the non-positive connection between the valve seat and the valve body is interrupted.The internal pressure caused by the hot gas continues to act on the valve body, pushing it out of the valve seat, or rather, "shooting" it, thus completely and permanently opening the flow channel. Unlike a check valve, the flow channel remains open even when the internal pressure drops again due to the release of the hot gas.

[0013] Such an emergency venting valve offers the advantage that the set pressure can be adjusted very precisely by adjusting the spring stiffness of the spring clamp unit. In terms of the reproducibility of the set pressure, the emergency venting valve is relatively insensitive to manufacturing, installation, and environmental influences. This advantageously eliminates the need for additional safety precautions, saving weight, space, and costs.

[0014] In a further development of the invention, the spring clamp unit has at least two spring clamp elements which, when the emergency degassing valve is closed, protrude into the flow channel and clamp the valve body in the valve seat. During the transition from the closed to the open state of the emergency degassing valve, the spring clamp elements are pressed by the valve body towards a wall of the flow channel. The spring clamp elements, which are located opposite one another in particular, clamp or clamp the valve body in the valve seat and thereby fix it in the valve seat. The spring clamp elements represent a constriction in the flow channel which the valve body cannot pass through because the diameter of the valve body is larger than the diameter of the flow channel in the region of the constriction.As soon as hot gas-induced internal pressure acts on the valve body, it is moved in the direction of flow, pushing the spring clamping elements toward the wall of the flow channel. By pushing back the spring clamping elements, the constriction is removed, allowing the valve body to move through the flow channel toward the surroundings until it has left the flow channel, providing the open state of the emergency degassing valve.

[0015] Preferably, the wall of the flow channel has receiving pockets for the spring clamping elements. When the emergency degassing valve is closed, the spring clamping elements partially protrude from the receiving pockets into the flow channel. During the transition from the closed to the open state of the emergency degassing valve, the spring clamping elements are pressed from the flow channel into the receiving pockets by the valve body. The receiving pockets can, for example, be bores in the wall of the flow channel. In the case of a tubular flow channel, these receiving pockets are oriented in the radial direction, with the spring force of the spring clamping elements acting on the valve body counter to the radial direction.

[0016] Particularly preferably, the valve body has a curved surface and the spring clamping elements each have a spring and a ball element attached to the spring. When the emergency degassing valve is closed, the ball elements rest against the curved surface of the valve body. During the transition from the closed to the open state of the emergency degassing valve, the ball elements slide over the curved surface of the valve body and are pushed back towards the wall of the flow channel. For example, the valve body can be designed as a spherical body, i.e. as a spherical valve body. A diameter of the spherical body is significantly larger than a diameter of the spherical elements. The valve body can also be mushroom-shaped, for example. Due to the curved surface of the valve body, the valve body has a decreasing diameter in the direction of flow.In the case of the spherical valve body, the point with the largest diameter is at the equator. When the emergency venting valve is closed, the spherical elements rest against the surface of the valve body, particularly in the area away from the point with the largest diameter, with the springs to which the spherical elements are attached being relaxed. When the internal pressure caused by the hot gas acts on the valve ball, the valve body is moved along the direction of flow. As the diameter of the valve body increases, the springs are compressed against the spring force and the spherical elements are pushed towards the wall of the flow channel, for example back into the receiving pockets. The spherical elements are then pushed back as far as possible when they are at the same height as the point with the largest diameter of the valve body.As soon as the valve body's largest diameter passes the ball elements, the valve body is ejected from the flow channel into the surrounding area like a cannonball due to the hot gas-induced internal pressure. The relaxing springs can also assist and accelerate the valve body's expulsion.

[0017] It can be provided that the emergency degassing valve has a support element for holding the valve body in the valve seat between an opening of the valve seat facing the interior and the valve body. This support element, which can be designed, for example, as a constriction of the flow channel in the region between the valve body and the opening facing the interior, can prevent the valve body from falling into the interior. The valve body can therefore only move in the direction of flow of the hot gas out of the flow channel. The support element can, for example, be formed integrally with the wall of the flow channel.

[0018] In an advantageous development of the invention, an opening of the valve seat facing the environment is covered by a cover element, wherein the valve body is designed to penetrate or detach from the cover element during the transition from the closed to the open state of the emergency degassing valve. The cover element can be designed, for example, as a protective film. The cover element can protect the emergency degassing valve from environmental influences, for example, from the penetration of water and dirt into the valve seat. The detached or pierced cover element can also serve as a visual indication of the triggered emergency degassing valve.

[0019] The invention also includes a motor vehicle with a high-voltage battery according to the invention. The motor vehicle is, in particular, an electric or hybrid vehicle and has the high-voltage battery as a traction battery for providing drive power for an electric drive motor of the motor vehicle.

[0020] The embodiments presented with reference to the emergency degassing valve according to the invention and their advantages apply accordingly to the battery housing according to the invention, to the high-voltage battery according to the invention and to the motor vehicle according to the invention.

[0021] Further features of the invention emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0022] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawings. They show: Fig. 1 a schematic representation of an embodiment of an emergency degassing valve according to the invention in a closed state; Fig. 2 the emergency degassing valve according to Fig. 1 when changing from the closed to the open state; and Fig. 3 the emergency degassing valve according to Fig. 1 and Fig. 2 in the open state.

[0023] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0024] Fig. 1, Fig. 2 and Fig. 3 show an embodiment of an emergency venting valve 1 in different states. The emergency venting valve 1 is arranged in a housing wall 2 of a battery housing of a high-voltage battery (not shown in full here). The high-voltage battery can be used as a traction battery in an electrically driven motor vehicle. The emergency venting valve 1 serves to release a hot gas located in an interior 3 of the battery housing from a predetermined overpressure threshold value into an environment 4 of the high-voltage battery to reduce the overpressure.

[0025] The emergency venting valve 1 has a valve seat 5, which here is tubular or designed as a tube 6. The valve seat 5 is arranged in an emergency venting opening 7 of the housing wall 2 and fastened to the housing wall 2. Sealing elements 8 between the housing wall 2 and the valve seat 5 seal the interior 3 of the battery housing from the environment 4. The valve seat 5 forms a flow channel 9 for the hot gas, through which the hot gas can escape from the interior 3 into the environment 4 along a flow direction S.

[0026] The emergency degassing valve 1 also has a valve body 10, which here is designed as a spherical body 11. The valve seat 5 has support elements 13 on a wall 12 of the valve seat 5, which hold the spherical body 11 in the tube 6. The support elements 13 can, for example, be formed integrally with the wall 12 and represent a constriction of the otherwise precisely fitting tube 6 for the spherical body 11.

[0027] The emergency degassing valve 1 also has a spring clamp unit 14, which is designed to provide a force-locking connection between the valve seat 5 and the valve body 10. A spring force of the spring clamp unit 14 acts obliquely, in particular perpendicular to the flow direction S of the hot gas. The spring clamp unit 14 here has two radially opposite spring clamp elements 15, each with a spring 16 and a ball element 17 attached thereto. The spring clamp elements 15 are each arranged in a receiving pocket 18 in the wall 12 of the valve seat 5. The receiving pockets 18 are designed, for example, as radial bores in the wall 12 of the flow channel 9. An opening of the flow channel 9 facing the interior 3 is also covered by a grid 19, and an opening of the flow channel 9 facing the environment 4 is covered by a cover element 20, for example, a protective film.The cover element 20 seals the flow channel 9 in addition to the spherical body 11 and also ensures that the emergency degassing valve 1 is protected from environmental influences.

[0028] In Fig. 1, the emergency degassing valve 1 is shown in a closed state. The springs 16 of the spring clamping elements 15 are relaxed, and the ball elements 17 protrude into the flow channel 9. The ball elements 17 rest against the curved surface of the ball body 11 and form a barrier in the flow channel 9 for the ball body 11 toward the environment 4, i.e., in the flow direction S of the hot gas. The spring force acting radially or laterally on the ball body 11 holds the ball body 11 in the tube 6.

[0029] As soon as a hot gas-related internal pressure P is present in the interior 3, which corresponds at least to a response pressure of the emergency degassing valve 1, the emergency degassing valve 1 goes, as in Fig. 2, from the closed state to the open state. The internal pressure P presses the spherical body 11 along the flow direction S through the pipe 6 towards the environment 4. The spherical body 11 moves past the spherical elements 17, which can slide along the surface of the spherical body 11. During this sliding movement, the spherical elements 17 are pressed against the spring force of the springs 16 towards the wall 12, whereby the springs 16 are compressed. The springs 16 are compressed until the spherical elements 17 are pushed into the receiving pockets 18. This occurs when the spherical elements 17 are located at the point of the valve body 10 with the largest diameter, here at the equator of the spherical body 11. It is also shown here that the valve body 10 detaches the cover element 20 from the opening of the flow channel 9 during the transition from the closed to the open state.

[0030] The spherical body 11 is suddenly shot into the environment 4 by the internal pressure P exceeding the set pressure, thus exposing the entire flow channel 9 to the hot gas. The spring clamping elements 15 can assist this expulsion of the spherical body 11 by relaxing the springs 16 after the largest diameter of the spherical body 11 has passed the spherical elements 17, thus forcing the spherical body 11 out of the tube 6. The spherical body 11 is thus propelled from the flow channel 9 into the environment 4 like a cannonball.

[0031] As soon as the valve body 10 has left the valve seat 5, the emergency degassing valve 1 is opened and the complete flow channel 9 is ready for the escaping hot gas.

[0032] This open state of the emergency degassing valve 1 is in Fig.3. The cover element 20, which is detached or pierced in this process, can serve as an optical signal for the open state of the emergency venting valve 1. Additionally, a sensor system can be provided that detects the activation of the emergency venting valve 1. This sensor system can transmit the detected activation to the on-board electronics system of the motor vehicle. This information from the sensor system about the activated emergency venting valve 1 can be used to detect an unusual event, for example, a fault in the high-voltage battery, or to verify the plausibility of an already detected unusual event.

Claims

[1] Emergency degassing valve (1) for a battery housing of a high-voltage battery for discharging a hot gas from an interior space (3) of the battery housing, comprising: - a valve seat (5) for fastening to the battery housing and for forming a flow channel (9) for the hot gas between the interior (3) and an environment (4) of the battery housing, - a valve body (10) for closing the flow channel (9), characterized by , that the emergency degassing valve (1) is designed as a spring-loaded full-stroke safety valve and has a spring clamping unit (14) arranged on the valve seat (5), which - to provide a closed state of the emergency degassing valve (1), it is designed to provide a force-locking connection between the valve seat (5) and the valve body (10) by exerting a spring force directed obliquely to a flow direction (S) of the hot gas on the valve body (10), and - to provide an open state of the emergency degassing valve (1), it is designed to interrupt the force-locking connection when an internal pressure acting on the valve body (10) due to hot gas and corresponding to a predetermined response pressure is applied, and to permanently remove the valve body (10) from the valve seat (5) while releasing the entire flow channel (9). [2] Emergency degassing valve (1) according to claim 1, characterized by , that the spring clamping unit (14) has at least two spring clamping elements (15) which, in the closed state of the emergency degassing valve (1), protrude into the flow channel (9) and thereby clamp the valve body (10) in the valve seat (5), and are pressed by the valve body (10) in the direction of a wall (12) of the flow channel (9) during the transition from the closed to the open state of the emergency degassing valve (1). [3] Emergency degassing valve (1) according to claim 2, characterized by , that the wall (12) of the flow channel (9) has receiving pockets (18) for the spring clamping elements (15), wherein the spring clamping elements (15) protrude partially from the receiving pockets (18) into the flow channel (9) when the emergency degassing valve (1) is in the closed state, and are pushed back from the flow channel (9) into the receiving pockets (18) by the valve body (10) when the emergency degassing valve (1) changes from the closed to the open state. [4] Emergency degassing valve (1) according to claim 2 or 3, characterized by , that the valve body (10) has a curved surface and the spring clamping elements (15) each have a spring (16) and a ball element (17) fastened to the spring (16), wherein the ball elements (17) rest on the curved surface of the valve body (10) in the closed state of the emergency degassing valve (1), and slide over the curved surface of the valve body (10) during the transition from the closed to the open state of the emergency degassing valve (1) and are pushed back in the direction of the wall (12) of the flow channel (9). [5] Emergency degassing valve (1) according to one of the preceding claims, characterized by , that the valve body (10) is designed as a spherical body (11) and the valve seat (5) is designed as a tube (6). [6] Emergency degassing valve (1) according to one of the preceding claims, characterized by, that the emergency degassing element (1) has a support element (13) for holding the valve body (10) in the valve seat (5) between an opening of the valve seat (5) facing the interior (3) and the valve body (10). [7] Emergency degassing valve (1) according to one of the preceding claims, characterized by , that an opening of the valve seat (5) facing the environment is covered by a cover element (20), in particular a protective film, wherein the valve body (10) is designed to penetrate the cover element (20) when leaving the flow channel (9) or to detach it from the opening. [8] Battery housing for a high-voltage battery with a plurality of housing walls (2) which enclose an interior space (3) for accommodating battery cells, and an emergency degassing valve (1) according to one of the preceding claims, wherein the emergency degassing valve (1) is arranged in one of the housing walls (2). [9] High-voltage battery with a battery housing according to claim 8 and a plurality of battery cells which are arranged in the interior (3) of the battery housing. [10] Motor vehicle with a high-voltage battery according to claim 9.

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