Traction battery of a motor vehicle and motor vehicle

Abstract

A traction battery (10) of a motor vehicle, comprising a plurality of battery cells (10), with compensation elements (11) arranged between adjacent battery cells (10), which are designed to compensate for a change in volume of the battery cells (10), wherein the compensation elements (11) each have opposing cover elements (13) and a frame element (14) arranged between or next to the cover elements (13). wherein a cavity (15) delimited at least by the cover elements (14) of the respective compensation element (11) is either directly filled with gas or accommodates a gas-filled gas cushion, and wherein groove-like depressions (17) are introduced into at least one of the cover elements (13) of the respective compensation element (11), which are designed to guide coolant.

Description

The invention relates to a traction battery of a motor vehicle and a motor vehicle having at least one traction battery.The structure of a traction battery of a motor vehicle is sufficiently known from practice. Thus, a traction battery has a plurality of battery cells. The battery cells are arranged either directly in a battery housing of the traction battery or indirectly in battery module housings of battery modules of the traction battery, which are positioned in the battery housing.Furthermore, it is known from practice that compensation elements are arranged between adjacent battery cells of a traction battery, which compensation elements serve to compensate for a change in volume of the battery cells. It is thus known that battery cells are exposed to an increase in volume during charging and to a decrease in volume during discharging, wherein such volume changes can be compensated for by means of the compensation elements.DE 10 2018 214 529 A1 discloses an accumulator arrangement having a plurality of battery cells, wherein a compressible intermediate insert is arranged between adjacent battery cells. The battery cells can be prestressed via the compressible intermediate insert; furthermore, a change in volume of the battery cells can be compensated for via the latter. Furthermore, the intermediate insert of the accumulator arrangement according to DE 10 2018 214 529 A1 serves as a cooling element, wherein for this purpose the intermediate insert has pores through which a coolant flows. Then, when the intermediate insert is compressed as a result of an increase in volume of adjacent battery cells, the flow cross section of the pores and thus a volume flow of the coolant or a mass flow of the coolant through the intermediate insert of the accumulator arrangement changes.DE 10 2018 108 962 A1 discloses a battery cell module comprising a plurality of battery cells and cooling units arranged between adjacent battery cells and between the battery cells and a module housing. The cooling units have opposite cover plates, wherein a biasing means extends between the cover plates. Then, when the cover plates of the cooling unit are compressed as a result of an increase in the volume of the battery cells, the flow cross section for the coolant and thus the volume flow or mass flow of coolant through the cooling units changes.There is a need for a novel traction battery with compensation elements between adjacent battery cells, wherein the compensation elements are intended to compensate for a change in volume of the battery cells, namely in such a way that, as a result of the compensation of the change in volume, the flow cross section for a coolant and thus a volume flow of coolant or mass flow of coolant does not change but remains constant.It is an object of the invention to provide a novel traction battery of a motor vehicle and a motor vehicle having at least one such traction battery.This object is achieved by a traction battery according to patent claim 1 and a motor vehicle according to patent claim 9.According to the invention, the compensation elements each have mutually opposite cover elements and a frame element arranged between or next to the cover elements. A cavity of the respective compensation element, which cavity is delimited at least by the cover elements of the respective compensation element, is either directly filled with gas or accommodates a gas cushion filled with gas. In at least one of the cover elements of the respective compensation element, groove-like depressions are introduced, which are configured for the guidance of coolant.In the traction battery according to the invention, the compensation elements can compensate for changes in volume of the battery cells, namely in that the distance between the cover elements of the compensation elements changes. As a result, the gas in the cavity of the compensation elements is compressed in the event of an increase in the volume of the battery cells and expanded in the event of a decrease in the volume of the battery cells.The groove-like depressions introduced into the respective compensation element, namely into the respective cover element thereof, maintain their contour during the deformation of the cover elements. When compensating for the change in volume of the battery cells, the flow cross section of the groove-like depressions for the coolant therefore does not change. Thus, an invariable mass flow or volume flow of coolant can be ensured by the groove-like depressions of the compensation elements independently of the volume of the battery cells.Accordingly, a constant cooling capacity can be ensured independently of the change in volume of the battery cells. The compensation elements allow effective support of the battery cells with respect to one another, and also pre-tensioning, wherein the pre-tensioning can be provided both by the material of the frame element and via the gas in the cavity of the respective compensation element.The cavity of the compensation elements can be filled with air or also with an inert gas. Then, when the cavity of the compensation elements is filled with inert gas, a fire protection effect can be provided.Preferably, groove-like depressions are introduced into both cover elements of the respective compensation element, which depressions are configured for the guidance of coolant. This is particularly preferred for advantageous cooling of the battery cells.Preferably, the groove-like depressions introduced into the two cover elements of the respective compensation element are offset with respect to one another in such a way that the groove-like depressions do not touch one another when the distance between the cover elements of the respective compensation element is reduced. This advantageously ensures that when groove-like depressions are introduced into both cover elements, the groove-like depressions do not touch one another despite a changing distance between the cover elements and the flow cross section of the same for the coolant thus remains unchanged and thus constant.Preferably, at least the cover elements and, in the case of a frame element arranged between the cover elements, also the frame element of the respective compensation element and the connection of the frame element to the cover elements are each gas-tight. This makes it possible to fill the respective cavity of the respective compensation element directly with gas.Preferably, when the cavity delimited by the cover elements and the frame element of the respective compensation element accommodates a gas cushion filled with gas, a casing of the gas cushion is gas-tight. If a cavity of a respective compensation element is filled with gas via a gas cushion, the casing of the gas cushion is gas-tight.Preferred developments of the invention are evident from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. The following shows: FIG. 1 shows a side view of two battery cells of a traction battery and a compensation element arranged between the battery cells, FIG. 2 shows the arrangement of FIG. 1 in a plan view in a first state, FIG. 3 shows the arrangement of FIG. 2 in a second state, FIG. 4 is an exploded view of a compensating element, FIG. 5 shows a cross section through a compensation element.FIGS. 1 and 2 show an arrangement of two battery cells 10 of a traction battery of a motor vehicle and a compensation element 11 arranged between the two battery cells 10, which compensation element is configured to compensate for a change in volume of the battery cells 10. Thus, the battery cells 10 can be subjected to an increase in volume during charging and to a decrease in volume during discharging. Such a change in volume of the battery cells 10 can be compensated for by means of the compensation element 11.In FIGS. 1 and 2, only two battery cells 10 are shown. A traction battery or a battery module of a traction battery comprises a plurality of such battery cells, wherein a compensation element 11 is arranged in each case between two adjacent battery cells 10. Such a compensation element 11 can also be arranged between a battery cell and an adjoining housing of the traction battery or of the battery module.In FIGS. 1 and 2, of the battery cells 10, poles 12 of the battery cells 10 are furthermore shown. It follows from the coordinate systems shown in FIGS. 1 and 2 that the poles 12 of the battery cells 11 are accessible in the vehicle transverse direction Y. In the vehicle longitudinal direction X, a plurality of battery cells 10 are stacked side by side with the interposition of compensation elements 11.The compensation element 11 visible in FIGS. 1, 2 has covering elements 13 lying opposite one another and a frame element 14 arranged between the covering elements 13; FIG. 4 shows an exploded view of a compensation element 11 with the two covering elements 13 and the frame element 14 running around the edge between the covering elements 13.The cover elements 13 and the frame element 14 delimit a cavity 15 within the respective compensation element 11, which cavity is either directly filled with a gas 16 or receives a gas cushion filled with gas.At least one groove-like depression 17 is introduced into at least one of the cover elements 13 of the respective compensation element 11, preferably into both cover elements 13 of the respective compensation element 11, which depression is configured for the guidance of coolant. As shown in FIG. 2, the groove-like depressions 17 are open on a side facing the respective battery cell 10, such that the coolant flowing through the groove-like depressions 17 flows directly along the respective battery cell 10 in order to cool the same directly.The groove-like depressions 17 project into the cavity 15 between the mutually opposite cover elements 13 of the respective compensation element 11, but do not allow coolant to enter the respective cavity 15.Then, when the groove-like depressions 17 are introduced into both cover elements 13 of the respective compensation element 11, as shown in FIG. 2, they are offset with respect to one another in such a way that the groove-like depressions 17 do not touch one another in the event of a reduction in the distance between the cover elements 13 (see FIG. 3 ), which is caused by an increase in the volume of the battery cells 10 to be compensated.Then, when the distance between the cover members 13 of the respective compensating member 11 changes due to a change in volume of the adjacent battery cells 12, the flow cross section of the groove-like recesses 17 remains unchanged. The coolant flow through the groove-like depressions 17 thus remains constant.Thus, on the one hand, an effective compensation of a changing volume of the battery cells 12 and, on the other hand, an effective cooling of the battery cells 10 independent thereof can be provided. Compression or expansion of the respective compensation element 11 leaves the coolant flow through the groove-like depressions 17 thereof unchanged.In the exemplary embodiment of FIGS. 1 to 3, the frame element 14 is arranged between the cover elements 13. The material of the frame element 14 can provide a prestress for the battery cells 10. This prestress can also be provided by means of the gas pressure of the gas in the cavity 15 of the respective compensation element 11.The gas 16 can be air or else in the inert gas. If inert gas is used, a fire protection function can be provided.If the cover elements 13 of the respective compensation element 11 are gas-tight and, in the exemplary embodiment of FIGS. 1 to 4, in which the frame element 14 is positioned between the cover elements 13, the frame element 14 and the connection between the frame element 14 and the cover elements 13 are each gas-tight, the cavity 15 can be directly filled with gas. If such a gas-tight design of the cover elements 13 and of the frame element 14 and of the connection between the frame element 14 and the cover elements 13 is not guaranteed, then alternatively a gas bag filled with gas can be arranged in the cavity 15, which then has a gas-tight envelope.A plastic, in particular a fiber-reinforced plastic, alternatively a metal, in particular a metal composite material, is suitable as the material for the cover elements 13 of the respective compensation element 11.Thus, the cover elements 13 can consist, for example, of a GRP or CFRP material.The frame element 14 of the respective compensation element 11 can be formed from an elastomer material and preferably have a Shore hardness of between 5 Shore A and 60 Shore A.When a gas bag filled with gas is arranged in the cavity 15, the gas-tight casing preferably consists of a gas-tight plastic film or a gas-tight metal foil, such as a gas-tight aluminum foil, or a gas-tight composite film, such as a gas-tight aluminum-plastic film, or a gas-tight metal sheet.In the exemplary embodiment of FIGS. 1 to 4, the groove-like recesses 17 each extend in the vehicle vertical direction (Z direction). In the region of each cover element 13, a plurality of groove-like recesses, which serve for the coolant guidance, run parallel to one another in the Z direction at a distance from one another. The orientation of the groove-like recesses 17 can, however, also run in the Y direction. Furthermore, the groove-like recesses 17 can also have curved, non-linear profiles.FIG. 5 shows a cross section through an alternative compensation element 11, wherein in FIG. 5 the frame element 14 is not arranged between the cover elements 13 but laterally next to the same. Thus, in FIG. 5, the opposite cover elements 13 are not connected to one another via the frame element 14, but rather via walls 18 which extend between the cover elements 13 and on which the frame element 14 ultimately engages. Thus, in FIG. 5, the cavity 15 for receiving the gas 16 is defined by the cover elements 13 and the walls 18 extending between the opposite cover elements 13, wherein the opposite cover elements 13 are connected to one another at projections 19 of the walls 18 projecting into the cavity 17. The walls are 90° bends of the cover elements 13 and the projections 19 are 90° bends of the walls 18.The invention further relates to a motor vehicle having at least one traction battery according to the invention.The motor vehicle is either an electric vehicle or a hybrid vehicle.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2018 214 529 A1

[0004] DE 10 2018 108 962 A1

[0005]

Claims

Traction battery of a motor vehicle, having a plurality of battery cells (10), having compensation elements (11) which are arranged between adjacent battery cells (10) and are designed to compensate for a change in volume of the battery cells (10), characterized in that the compensation elements (11) each have mutually opposite cover elements (13) and a frame element (14) arranged between or next to the cover elements (13), a cavity (15) which is delimited at least by the cover elements (14) of the respective compensation element (11) is either directly filled with gas or receives a gas cushion which is filled with gas, in at least one of the cover elements (13) of the respective compensation element (11) there being introduced groove-like depressions (17) which are designed to guide coolant.Traction battery according to Claim 1, characterized in that groove-like depressions (17) are introduced into both cover elements (13) of the respective compensation element (11), said depressions being configured for carrying coolant.Traction battery according to Claim 2, characterized in that the groove-like depressions (17) introduced into the two cover elements (13) of the respective compensation element (11) are offset with respect to one another in such a way that the groove-like depressions (17) do not touch one another in the event of a reduction in the distance between the cover elements (13) of the respective compensation element (11).Traction battery according to one of Claims 1 to 3, characterized in that at least the covering elements (13) and, in the case of a frame element (14) arranged between the covering elements (13), also the frame element (14) of the respective compensation element (11) and also the connection of the frame element (14) to the covering elements (13) are in each case gas-tight.Traction battery according to one of Claims 1 to 4, characterized in that the covering elements (13) of the respective compensation element (11) are formed on a plastic or a fibre composite plastic or a metal made of a metal composite material.Traction battery according to one of Claims 1 to 5, characterized in that the frame element (14) of the respective compensation element (11) is formed from an elastomer material.Traction battery according to one of Claims 1 to 6, characterized in that the gas cushion has a gas-tight casing.Traction battery according to Claim 7, characterized in that the gas-tight casing consists of a plastic film or metal foil or composite film or a metal sheet.Motor vehicle having at least one traction battery (10) according to one of Claims 1 to 8.

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