Battery for an electric vehicle

Abstract

Battery (10) for an electric vehicle, with at least one battery module (12, 14, 16), a cooling device (21), and a coupling device (32) which is designed such that the battery module (12, 14, 16) is thermally connected to the cooling device (21) via the coupling device (32), characterized in that the coupling device (32) has a cooling device-side coupling element (36) and a battery module-side coupling element (34), each having a coupling element-specific heat transfer surface (341, 361) via which the coupling elements (34, 36) abut one another in such a way that an overlay of the coupling element-specific heat transfer surfaces (341, 361) defines an effective heat transfer surface (38), wherein the coupling elements (34, 36) are displaceable relative to one another in such a way that the effective heat transfer surface (38) dependent on the relative position between the two coupling elements (34, 36) is adjustable, wherein one of the two coupling elements (34, 36) is rotatable and the other coupling element (34, 36) is rigidly arranged or both coupling elements (34, 36) are rotatable.

Description

[0001] The invention relates to a battery with at least one battery module, a cooling device, and a coupling device, which is designed such that the battery module is thermally connected to the cooling device via the coupling device.

[0002] Such batteries are generally known from the prior art and typically comprise multiple battery modules that heat up during operation and require cooling due to this heating. To cool the battery modules, the batteries typically comprise a cooling device, in particular a cooling plate, which is thermally coupled to the battery modules via a respective coupling device. Such a battery is disclosed, for example, in DE 10 2019 134 490 A1, wherein the battery comprises multiple battery modules and a cooling plate, wherein the battery modules are each thermally connected to the cooling plate via a respective coupling device.

[0003] The battery modules or the battery cells of the battery modules are subject to an aging process, whereby the condition of a battery module in relation to the aging state is qualified by the so-called "State of Health" (SOH) and is usually specified with a percentage value between 0% and 100%. For example, an SOH of 80% means that the battery module has a capacity of 80% compared to the original capacity. The battery modules are usually connected electrically in series, which is why the aim is for the SOH of all battery modules connected in series to be as equal as possible. An important factor influencing the aging process, i.e. the SOH, is the temperature or the temperature profile of the battery modules. The battery modules can change depending on various factors, for example tolerances and fluctuations in the manufacturing process of the battery modules orthe battery cells of the battery modules, heat up differently during operation. Furthermore, the battery modules are usually cooled with different cooling effects during operation because a cooling device designed as a cooling plate through which coolant flows has an inhomogeneous temperature distribution during battery operation. In particular, the temperature of the coolant flowing through the cooling plate rises continuously from a coolant inlet, i.e. from a cold side, to a coolant outlet, i.e. a warm side, due to the heat transfer between the battery modules and the cooling plate, with a warmer coolant absorbing less heat from the battery modules than a colder coolant. This results in a lower cooling effect on the battery modules arranged closer to the warm side than on the battery modules arranged on the cold side.

[0004] From US 2005 / 0 074 666 A1 a battery is known which comprises a battery module, a cooling device and a coupling device, wherein the coupling device is designed such that the battery module can be thermally connected to the cooling device via the coupling device in such a way that an effective heat transfer surface can be adjusted by adjusting the coupling device, whereby the heat transfer between the battery module and the cooling device can be adjusted.

[0005] From DE 10 2019 123 908 A1, a heat dissipation device for heat dissipation with a heat source, a heat sink and a heat conducting element for transferring heat energy from the heat source to the heat sink is known, wherein the heat conducting element is arranged on the heat source and the heat sink and physically changes with increasing temperature of the heat conducting element in such a way that a first cross-sectional area between the heat source and the heat conducting element and / or a second cross-sectional area between the heat conducting element and the heat sink increases, and / or the length of the heat conduction path shortens.

[0006] From DE 10 2014 015 741 A1 a battery and a cooling plate are known, wherein the cooling plate can be automatically thermally decoupled from the battery when a predetermined threshold value of an electrical power loss of at least one electrically operated component and / or a temperature control is exceeded in the absence of a temperature control requirement.

[0007] DE 10 2019 104 130 A1 discloses a battery housing with a housing wall for defining a housing interior. The housing wall has a double-walled housing wall section with adjustable thermal conductivity. An air gap is formed between an inner wall and an outer wall of the double-walled housing wall section. The air gap can be adjusted by means of an actuator, thereby adjusting the thermal conductivity of the housing wall section.

[0008] The object of the invention is to provide a battery which has such a cooling of the battery module that the aging process of the battery module or the battery cells of the battery module can be influenced in a simple manner.

[0009] The problem is solved by the features of claim 1.

[0010] According to the invention, the coupling device comprises a cooling device-side coupling element and a battery module-side coupling element, each of which has a coupling-element-specific heat transfer surface, via which the coupling elements abut one another in such a way that an overlap of the coupling-element-specific heat transfer surfaces of the coupling elements defines an effective heat transfer surface. The coupling elements are displaceable relative to one another in such a way that the effective heat transfer surface, which depends on the relative position between the two coupling elements, is adjustable. Depending on the relative position of the coupling elements to one another, the effective heat transfer surface can vary between 100% and 0%, preferably between 100% and 20%.

[0011] In this way, adjustable cooling of the battery module can be provided, wherein the cooling device can be designed as is basically known from the prior art and only the heat transfer between the cooling device and the battery module can be adjusted via the coupling device according to the invention. As a result, for example, in the event of strong heating of the battery module and / or a heated coolant, i.e. with reduced heat transfer and thus a reduced cooling effect, the effective heat transfer surface can be specifically increased by appropriately positioning the coupling elements relative to one another, thus ensuring sufficient cooling. Otherwise, if the battery module heats up slightly, the effective heat transfer surface can be reduced by shifting the coupling elements relative to one another.

[0012] This makes it possible to provide demand-based cooling of the battery module in a simple and cost-effective manner, i.e., to specifically adjust the cooling of the battery module, thereby specifically influencing the aging process of the battery modules. The coupling device according to the invention merely needs to be thermally interposed between the battery module and the cooling device.

[0013] One of the two coupling elements is rotatable and the other coupling element is rigidly arranged, or both coupling elements are rotatable. By adjusting the effective heat transfer device by rotating one or both coupling elements, the coupling device can be designed to save space. The coupling elements are preferably asymmetrical and preferably have a common central axis, which forms the axis of rotation of the coupling element(s). The coupling element-specific heat transfer surfaces preferably have a rectangular shape such that a maximum effective heat transfer surface is present when the longitudinal axes of the coupling elements are aligned the same, and a minimum effective heat transfer surface is present when the longitudinal axes of the coupling elements are aligned perpendicular to one another.The effective heat transfer area can be continuously varied between the two extreme positions, allowing the heat transfer between the battery module and the cooling device to be precisely adjusted.

[0014] Preferably, an actuator is provided which is connected to the rotatable coupling element in such a way that the coupling element can be actively adjusted by the actuator. This allows the displaceable coupling element or the displaceable coupling elements to be adjusted as needed, i.e. depending on the required cooling of the battery module. The actuator is in particular an electric actuator which has an electric motor and optionally a gear. The rotatable coupling element can preferably be spring-loaded by a spring element in such a way that, in the event of a defect in the actuator, the maximum effective heat transfer surface is present and thus the maximum possible cooling of the battery module is provided. This can prevent a battery module from overheating if the actuator experiences a fault.

[0015] In a preferred embodiment, the battery module-side coupling element is adjustable, wherein the battery module-side coupling element each has a coupling-element-specific heat transfer surface on the battery module side and on the coupling element side, wherein the coupling-element-specific heat transfer surface interacts with a battery module-specific heat transfer surface such that an effective heat transfer surface between the battery module and the battery module-side coupling element can be adjusted by rotating the battery module-side coupling element. This allows a relatively wide adjustment range for the heat transfer to be provided, since upon adjustment of the battery module-side coupling element, both the effective heat transfer surface between the coupling elements and the effective heat transfer surface between the battery module and the corresponding coupling element can be adjusted.

[0016] Preferably, a control unit and a temperature sensor are provided for detecting a temperature of a battery module, wherein the control unit is signal-connected to the temperature sensor and to the actuator, and wherein the control unit is designed to transmit a rotation signal to the actuator for rotating the rotatable coupling element as a function of the sensor signal from the temperature sensor. As a result, battery-module-specific and situation-dependent cooling can be provided by detecting the temperature of the battery module and, as a function thereof, adjusting the heat transfer between the battery module and the cooling device by the coupling device, i.e., by displacing the coupling elements relative to one another and by the resulting change in the effective heat transfer surface.

[0017] In a preferred embodiment, a plurality of battery modules are provided, each of which is thermally connected to the cooling device via a coupling device. The battery modules are preferably electrically connected in series. Because each battery module is thermally connected to the cooling device via a coupling device, a battery-module-specific cooling system can be set for each battery module. The effective heat transfer surface of each coupling device assigned to a respective battery module is specifically set. Preferably, a temperature sensor is provided on each battery module, wherein the effective heat transfer surfaces can be set by adjusting the relative positions of the coupling elements, in particular by a respective actuator, depending on the corresponding sensor signals from the temperature sensors.This allows the aging process of the battery modules, especially those connected electrically in series, to be specifically influenced.

[0018] The cooling device is preferably a cooling plate through which coolant flows, wherein the cooling plate has a coolant inlet and a coolant outlet, which are fluidly connected to one another via at least one coolant channel running through the cooling plate. This makes it possible to provide reliable cooling of the battery module(s) that is sufficient for the operation of the battery, with continuous heat dissipation taking place through the circulation of the coolant through a cooling circuit and the cooling plate. Alternatively, the cooling device can also be designed differently. For example, the cooling device can be a housing with air flow around it, which optionally has a plurality of air-circulated cooling fins.

[0019] An embodiment of the invention is explained in more detail with reference to the drawings. Fig. 1 shows schematically a battery in a side view, Fig. 2 shows part of the battery Fig. 1 in a perspective view.

[0020] The Fig. 1 shows a battery 10 of an electric vehicle, which is designed in particular as a traction battery and serves to supply at least one traction motor of the electric vehicle with electrical energy.

[0021] The battery 10 has a plurality of battery modules 12, 14, 16, which usually comprise a plurality of interconnected, in the Fig. 1. The battery modules 12, 14, 16 are electrically interconnected, in particular electrically connected in series.

[0022] The battery modules 12, 14, 16 or the battery cells of the battery modules 12, 14, 16 heat up during operation and require cooling. For this purpose, the battery 10 has a cooling device 21. The cooling device 21 is designed as a cooling plate 22 through which a coolant flows. The cooling plate 22 is fluidly connected to a cooling circuit 20 via a coolant inlet 222 and a coolant outlet 221. The cooling circuit 20 also has a coolant pump 24 and a heat exchanger 26.

[0023] To provide cooling for the battery modules 12, 14, 16 by the cooling plate 22, a thermal coupling of the battery modules 12, 14, 16 to the cooling plate 22 is required. For this purpose, the battery 10 has a coupling arrangement 30 with a plurality of coupling devices 32, wherein each coupling device 32 is assigned to a battery module 12, 14, 16, such that the heat transfer between a battery module 12, 14, 16 and the cooling plate 22 takes place via a respective coupling device 32. Each coupling device 32 has a battery module-side coupling element 34 and a cooling device-side coupling element 36. The coupling elements 34, 36 are made of a material with high thermal conductivity, in particular of a metallic material.

[0024] The explanation of the functioning of the coupling devices 32 is based on the Fig. 2, where Fig. 2 only the battery module 12, the cooling plate 22 and the coupling device 32 associated with the battery module 12 are shown.

[0025] The coupling elements 34, 36 are cuboid-shaped and each have a coupling-element-specific heat transfer surface 341, 361 with a rectangular cross-section, via which the two coupling elements 34, 36 abut one another and are thus thermally connected. The rectangular cross-section is defined by a length L1, L2 and a width B1, B2. An overlay of the coupling element-specific heat transfer surfaces 341, 361 defines an effective heat transfer surface 38 between the coupling elements 34, 36. The battery module-side coupling element 34 also has, on a side facing the battery module 12, a battery module-side heat transfer surface 234, through which the battery module-side coupling element 34 bears against a heat transfer surface 121 of the battery module 12, 14, 16 for heat transfer between the battery module 12 and the battery module-side coupling element 34.The battery module-side heat transfer surface 234 and the heat transfer surface 121 define an effective heat transfer surface 39.

[0026] The cooling device-side coupling element 36 has, on a side facing the cooling plate 22, a cooling device-side heat transfer surface 362, via which the cooling device-side coupling element 36 rests against a heat transfer surface of the cooling plate 22 for heat transfer between the cooling device-side coupling element 36 and the cooling plate 22.

[0027] The battery modules 12, 14, 16 or the battery cells of the battery modules 12, 14, 16 are subject to an aging process, whereby the battery modules 12, 14, 16 exhibit an actual capacity during aging that is reduced compared to their original capacity. The total capacity of the battery 10 is significantly determined by the aging state of the individual battery modules 12, 14, 16 connected electrically in series. Therefore, the aim is to ensure that the aging state and thus the capacity of all battery modules 12, 14, 16 connected in series are as uniform as possible. An important factor influencing the aging process of the battery modules 12, 14, 16 or the battery cells of the battery modules 12, 14, 16 is the temperature or the temperature profile of the battery modules 12, 14, 16, whereby the battery modules 12, 14, 16 may age due to various factors, for example due to tolerances and fluctuations in the manufacturing process of the battery modules 12, 14, 16 orthe battery cells of the battery modules 12, 14, 16 heat up differently during operation. Furthermore, the battery modules 12, 14, 16 are cooled with different cooling effects during operation because the cooling plate 22 has an inhomogeneous temperature distribution during operation of the battery 10. The temperature of the coolant flowing through the cooling plate 22 increases continuously from the coolant inlet 222, i.e. from a cold side, to the coolant outlet 221, i.e. a warm side, so that the coolant generally has a lower cooling effect on the battery module 16, which is arranged closer to the warm side, than on the battery module 12, which is arranged on the cold side.

[0028] In order to keep the aging process of the battery modules 12, 14, 16 consistent, the cooling devices 32 are designed such that the individual battery modules 12, 14, 16 can be cooled as needed. For this purpose, the battery module-side coupling element 34 is mounted so as to be rotatable about a rotation axis D and is operatively connected to an electric actuator 42. By actuating the actuator 42, the battery module-side coupling element 34 can be rotated about the rotation axis D, wherein the actuator 42 can be controlled by a control unit 50. In addition to the signal-based coupling to the actuator 42, the control unit 50 is also signal-based connected to a temperature sensor 40, wherein the temperature sensor 40 is arranged on the battery module 12 and serves to detect the temperature of the battery module 12.The control unit 50 is designed to transmit a rotation signal to the actuator 42 for rotating the battery module-side coupling element 34 depending on the sensor signal from the temperature sensor 40. Different control signals are stored in the control unit 50, for example, for different temperatures, whereby different relative positions between the coupling elements 34, 36 can be set using the different control signals.

[0029] By rotating the battery module-side coupling element 34, the effective heat transfer area 38 between the coupling elements 34, 36 can be changed, thereby changing the level of heat transfer between the coupling elements 34, 36. The heat transfer area 38 varies depending on the rotational position of the battery module-side coupling element 34, i.e., depending on the relative position between the coupling elements 34, 36.

[0030] In addition to the change in the effective heat transfer surface 38 between the coupling elements 34, 36, the effective heat transfer surface 39 between the battery module-side coupling element 34 and the battery module 12, 14, 16 also changes when the battery module-side coupling element 34 is rotated. Thus, when the battery module-side coupling element 34 is rotated, both effective heat transfer surfaces 38, 39 change, wherein when the coupling element 34 is rotated, the effective heat transfer surfaces 38, 39 change equivalently to one another, ie increase or decrease in size.

[0031] In the case of a Fig. 1 and Fig.In the embodiment shown in Figure 2, maximum heat transfer, i.e., maximum effective heat transfer surfaces 38, 39, would occur if the battery module-side coupling element 34 has an orientation corresponding to the cooling device-side coupling element 36 and the battery module 12, 14, 16, in which the longitudinal axes of the coupling elements 34, 36 and of the battery module 12, 14, 16 overlap. Minimum heat transfer, i.e., the smallest possible effective heat transfer surfaces 38, 39, would occur if the battery module-side coupling element 34 were rotated by 90° relative to the cooling device-side coupling element 36 and to the battery module 12, 14, 16.

Claims

[1] Battery (10) for an electric vehicle, with at least one battery module (12, 14, 16), a cooling device (21), and a coupling device (32) which is designed such that the battery module (12, 14, 16) is thermally connected to the cooling device (21) via the coupling device (32), characterized by , that the coupling device (32) has a cooling device-side coupling element (36) and a battery module-side coupling element (34), each having a coupling element-specific heat transfer surface (341, 361) via which the coupling elements (34, 36) abut one another in such a way that an overlay of the coupling element-specific heat transfer surfaces (341, 361) defines an effective heat transfer surface (38), wherein the coupling elements (34, 36) are displaceable relative to one another in such a way that the effective heat transfer surface (38) dependent on the relative position between the two coupling elements (34, 36) is adjustable, wherein one of the two coupling elements (34, 36) is rotatable and the other coupling element (34, 36) is rigidly arranged or both coupling elements (34, 36) are rotatable. [2] Battery (10) according to claim 1, characterized by that an actuator (42) is provided which is connected to the rotatable coupling element (34) in such a way that the coupling element (34) can be actively adjusted by the actuator (42). [3] Battery (10) according to claim 2, characterized bythat a control unit (50) and a temperature sensor (40) are provided for detecting a temperature of a battery module (12, 14, 16), wherein the control unit (50) is connected to the temperature sensor (40) and to the actuator (42) in terms of signals, and wherein the control unit (50) is designed to transmit a rotation signal to the actuator (42) for rotating the rotatable coupling element (34, 36) as a function of the sensor signal of the temperature sensor (40). [4] Battery (10) according to one of the preceding claims, characterized by that the coupling element-specific heat transfer surfaces (341, 361) have a rectangular shape, such that with the same orientation of a longitudinal axis of the coupling elements (34, 36) there is a maximum effective heat transfer surface (38) and with a mutually perpendicular orientation of the longitudinal axis of the coupling elements (34, 36) there is a minimum effective heat transfer surface (38). [5] Battery (10) according to one of the preceding claims, characterized by in that the battery module-side coupling element (34) is adjustable, wherein the battery module-side coupling element (34) has a coupling element-specific heat transfer surface (234, 341) on the battery module side and on the coupling element side, wherein the battery module-side, coupling element-specific heat transfer surface (234) interacts with a battery module-specific heat transfer surface (121) in such a way that an effective heat transfer surface (39) between the battery module (12, 14, 16) and the battery module-side coupling element (34) can be adjusted by rotating the battery module-side coupling element (34). [6] Battery (10) according to one of the preceding claims, characterized by that a plurality of battery modules (12, 14, 16) are provided, which are each thermally connected to the cooling device (21) via a coupling device (32). [7] Battery (10) according to one of the preceding claims, characterized by that the cooling device (21) is a cooling plate (22) through which coolant flows, wherein the cooling plate (22) has a coolant inlet (222) and a coolant outlet (221) which are fluidically connected to one another via at least one coolant channel running through the cooling plate (22).

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