drive battery assembly

Abstract

Drive battery assembly (10) for a hydrogen, electric or hybrid vehicle, comprising at least two battery modules (12, 14), each comprising a cooling surface (26, 28) and several, in particular prismatic, battery cells, and a cooling device (16) for cooling the battery modules (12, 14), wherein the cooling device (16) has at least two adjacent, separate cooling elements (18), each having several cooling fluid-carrying channels (20) for heat removal, characterized in that the cooling surfaces (26, 28) face each other and the cooling device (16) is arranged between the cooling surfaces (26, 28), wherein the cooling elements (18) bear against the cooling surfaces (26, 28) with their respective opposite outer surfaces (22, 24).

Description

[0001] The invention relates to a drive battery assembly for a hydrogen, electric or hybrid vehicle.

[0002] Due to the environmental impact of vehicles powered solely by combustion engines, the development of vehicle drive systems is increasingly moving toward electric drives, which at least partially replace conventional combustion engines. Electric drives typically feature a drive battery assembly through which the electric drive generates its power. The drive battery assembly comprises at least one battery pack, which is made up of at least one battery module containing multiple battery cells. The battery packs or battery modules used are high-voltage batteries, which can have voltages of 130 to 360 V. Since the batteries release heat during charging and discharging, they must be cooled to maintain optimal performance.This is achieved using a cooling device through which a cooling fluid or refrigerant flows to dissipate the heat energy generated by the batteries. Cooling the batteries also extends their service life. Typically, the battery cells must be kept below 40 to 50°C, although this depends on the type of battery used.

[0003] It is known from the prior art to provide each battery module with its own cooling device, which completely encloses the battery module or is pressed against it to ensure that the battery module is cooled to the appropriate temperature. However, this has proven disadvantageous in that the cooling devices are overall very heavy, which also increases the weight of the entire battery assembly. This, in turn, reduces the efficiency of the electric drive.

[0004] Battery modules with a cooling device are known from DE 10 2009 040 197 A1, DE 10 2010 032 900 A1 and DE 10 2010 051 106 A1.

[0005] The object of the invention is to provide a traction battery assembly with a cooling device that is lightweight and efficient.

[0006] The object of the invention is achieved by a drive battery assembly according to claim 1.

[0007] The basic idea of ​​the invention is that both outer surfaces of the cooling element are used for cooling, so that one cooling element cools two battery modules simultaneously. This is particularly efficient when the heat transfer coefficient of the refrigerant is significantly higher than the heat transfer coefficient between the cooling device and the cooling surface of the battery modules. The cooling elements can then be used to cool two battery modules without significant performance losses. This is due, among other things, to the fact that the cooling elements, due to their design with multiple channels, can be pressurized with the refrigerant R744, as the cooling elements meet the requirements for the prescribed minimum burst pressure.The separate design of the cooling device's multiple cooling elements also ensures greater flexibility, as unevenness in the battery pack surface to be cooled can be compensated for more effectively than with a continuous cooling plate. The weight of the cooling device is also reduced because the number of cooling elements is reduced, in particular halved. This creates a lighter cooling device, which has a positive effect on the power-to-weight ratio and the efficiency of the entire drive battery assembly. Furthermore, the cost of the drive battery assembly is reduced at the same time, as the cooling device has fewer cooling elements, which incur costs.

[0008] One aspect of the invention provides that the cooling elements together bear against 30% to 70%, preferably 40% to 60%, of the opposing cooling surfaces of the battery modules. It has been found that this partial area of ​​the cooling surface of the battery modules is already sufficient to ensure the required cooling of the battery modules. The battery modules can, in particular, have special cooling contact surfaces formed on the cooling surfaces and corresponding to the outer surfaces of the cooling elements. The cooling contact surfaces can be made of a material with a particularly high heat transfer coefficient, so that the cooling elements have high thermal conductivity.

[0009] In particular, the cooling elements are each essentially plate-shaped. This ensures that the cooling elements interact primarily via their main surfaces, through which they also contact the cooling surfaces or cooling contact surfaces. Inefficient cooling of the surroundings is thus avoided.

[0010] According to a further aspect of the invention, the cooling device comprises four cooling elements, each of which has a width between 10 mm and 40 mm, preferably between 15 mm and 30 mm. The cooling device can be more flexibly adjusted by varying the number of cooling elements and their width. This fine adjustment of the cooling device enables even more efficient cooling of the battery modules.

[0011] A further aspect of the invention provides for the cooling fluid to flow through the channels of a cooling element in the same flow direction. This simplifies the design of the cooling device, as a cooling element can be easily fluidically connected to a collector or distributor.

[0012] However, a reversal of flow direction between two adjacent channels within a cooling element can be provided if this is appropriate.

[0013] In particular, cooling elements are provided in pairs, with the same flow direction. This further simplifies the construction of the entire cooling device, as distributors and collectors connected to the cooling elements can be easily formed. This is particularly the case when an even number of cooling elements is provided. Furthermore, this allows for a distribution of the cooling fluid, enabling efficient cooling of the battery.

[0014] According to a further aspect of the invention, the cooling elements are pressed between the battery modules. This pressing ensures good thermal contact between the cooling surfaces, resulting in high efficiency of the entire cooling device.

[0015] In particular, the battery modules can be coupled to one another via at least one fixing element. The fixing element serves to securely mount the battery modules. Furthermore, the fixing element can press the two battery modules against each other, thereby pressing the cooling elements between the battery modules. Furthermore, this ensures that the cooling elements rest securely against the cooling surfaces of the battery modules.

[0016] A further aspect of the invention provides for at least one spring element to be provided in the force flow between the battery modules and the fixing element, so that the battery modules are subjected to a spring force against each other. The spring element can be used to adjust the preload force exerted on the cooling elements, thus preventing damage to the cooling elements or other components.

[0017] Furthermore, the battery modules can be compressed springily because the battery cell housings can be made of aluminum.

[0018] In particular, the cooling elements are designed to be flexible. This flexible design allows for better compensation of unevenness in the battery modules. Furthermore, it ensures excellent thermal contact between the cooling elements and the battery modules when pressed together.

[0019] Further advantages and features of the invention will become apparent from the following description and the drawings, to which reference is made. In the drawings: - Fig. 1 a schematic sectional view of the drive battery assembly according to the invention, and - Fig. 2 a perspective view of the cooling device used.

[0020] In Fig. 1, a drive battery assembly 10 is shown schematically in section, which comprises a first battery module 12 and a second battery module 14 as well as a cooling device 16.

[0021] The battery modules 12, 14 typically have several battery cells, which are not shown in detail here for the sake of clarity.

[0022] In the embodiment shown, the cooling device 16 comprises four cooling elements 18, each having a plurality of channels 20 through which a cooling fluid flows, which transports away the heat energy generated by the battery cells.

[0023] The cooling elements 18 each have a first outer surface 22 and a second outer surface 24, which are arranged opposite one another. Via the outer surfaces 22, 24, the cooling elements 18 rest against cooling surfaces 26, 28 of the battery modules 12, 14, which are arranged opposite one another with their cooling surfaces 26, 28 to be cooled.

[0024] The cooling elements 18 are in particular plate-shaped, so that the two outer surfaces 22, 24 are the main surfaces of the cooling elements 18.

[0025] As from Fig. 1, the outer surfaces 22, 24 of all cooling elements 18 only partially cover the cooling surfaces 26, 28 of the battery modules 12, 14. This partial surface can be between 30% and 70%, preferably between 40% and 60%, of the respective cooling surface 26, 28. This partial surface is also referred to as the cooling contact surface, since it is the surface with which the cooling elements 18 are in contact.

[0026] The battery modules 12, 14 are arranged in particular in such a way with respect to the flow direction of the cooling fluid within the channels 20 that the battery cells, which are arranged with respect to Fig. 1, which can extend across the entire height and width of the battery modules 12, 14, are arranged transversely to the alignment of the cooling elements 18 and the channels 20. The battery cells are therefore thin, plate-shaped cells stacked on top of one another in layers. This alignment of the cells with respect to the channels improves the cooling of the battery cells and allows the cooling device 16 to only contact a partial surface of the cooling surface 26, 28 of each battery cell to achieve sufficient cooling of the battery cells.

[0027] This is particularly due to the fact that the individual battery cells can have an aluminum housing, which is directly contacted by the cooling elements 18, which can also be a metallic extrusion profile. The aluminum housing of the battery cells thus acts as a heat-conducting surface itself.

[0028] It can further be provided that the battery modules 12, 14 have specially designed cooling contact surfaces on their cooling surfaces 26, 28, which correspond exactly to the outer surfaces 22, 24 of the cooling elements 18. These cooling contact surfaces can have a higher heat transfer coefficient than the other cooling surfaces 26, 28, so that the heat can be dissipated even more effectively.

[0029] It is also in Fig. 1 shows that the drive battery assembly 10 has a pretensioning device 30 which, in the embodiment shown, comprises two fixing elements 32 and four spring elements 34, wherein two spring elements 34 are each assigned to a fixing element 32, in particular to both ends of a fixing element 32.

[0030] The pretensioning device 30 ensures that the two battery modules 12, 14 are subjected to force against each other and the cooling elements 18 are pressed between the two cooling surfaces 26, 28.

[0031] The preload force on the cooling elements 18 establishes good thermal contact between the outer surfaces 22, 24 of the cooling elements 18 and the cooling surfaces 26, 28.

[0032] The preload force exerted by the preload device 30 on the battery modules 12, 14 is adjusted by the spring force of the spring elements 34. Since the spring elements 34 press against the associated ends of the fixing elements 32 with one end and against the battery modules 12, 14 with the other end, the maximum compressive force corresponds to the spring force of the spring elements 34. This can prevent damage to the cooling elements 18.

[0033] Since the cooling elements 18 can be plate-shaped extrusion profiles, they also have a high strength.

[0034] The two battery modules 12, 14 can be effectively cooled despite the smaller number, in particular half, of cooling elements 18, since the heat transfer coefficient of the refrigerant, for example R744, is a factor of 5 to 10 higher than the heat transfer coefficient from the cooling element 18 to the battery module 12, 14. The performance loss when cooling two battery modules 12, 14 simultaneously is therefore only 8% compared to cooling only one battery module 12, 14.

[0035] However, this loss of performance can be compensated by the number of channels 20 in the cooling element 18, since a larger number of channels 20 forms a larger effective surface with which the refrigerant can interact.

[0036] Fig.Figure 2 shows the cooling device 16 without battery modules 12, 14. The flow direction of the cooling fluid within the cooling elements 18 is also indicated by the arrows. In addition to the four cooling elements 18, the cooling device 16 comprises a distributor 36, a collector / distributor 38, and a collector 40.

[0037] The distributor 36 has an inlet pipe 42 for the cooling fluid and distributes it to two cooling elements 18a, 18b arranged side by side. The cooling fluid thus flows through the cooling elements 18a, 18b in pairs, starting from the distributor 36 and reaching the collector / distributor 38 in the same flow direction.

[0038] In the collector / distributor 38, the cooling fluid collected by the cooling elements 18a, 18b is distributed to the cooling elements 18c, 18d. The cooling fluid flows via the cooling elements 18c, 18d to the collector 40 and exits the cooling device 16 via an outlet pipe 44 provided there.

[0039] Partition walls may be arranged within the collector / distributor 38 so that the flow of the cooling fluid is directed accordingly.

[0040] Furthermore, the distributor 36 and the collector 40 can be formed in one piece, wherein a substantially centrally arranged partition wall ensures that separate collection and distribution sections are present in the one-piece design.

[0041] The drive battery assembly 10 according to the invention thus provides effective and efficient cooling of two battery modules 12, 14 with only a single cooling device 16, which is also lightweight since the cooling elements 18 do not extend over the entire cooling surfaces 26, 28 of the battery modules 12, 14.

[0042] The cooling device designed in this way is also suitable for cooling only one cooling surface of a battery module.

Claims

[1] Drive battery assembly (10) for a hydrogen, electric or hybrid vehicle, with at least two battery modules (12, 14), each comprising a cooling surface (26, 28) and a plurality of, in particular prismatic, battery cells, and a cooling device (16) for cooling the battery modules (12, 14), wherein the cooling device (16) has at least two separate cooling elements (18) arranged next to one another, each having a plurality of cooling fluid-carrying channels (20) for dissipating heat, characterized by that the cooling surfaces (26, 28) face each other and the cooling device (16) is arranged between the cooling surfaces (26, 28), wherein the cooling elements (18) bear against the cooling surfaces (26, 28) with their respective opposite outer surfaces (22, 24). [2] Drive battery assembly (10) according to claim 1, characterized by that the cooling elements (18) together bear against 30% to 70%, preferably 40% to 60% of the cooling surfaces (26, 28) of the battery modules (12, 14). [3] Drive battery assembly (10) according to claim 1 or 2, characterized by that the cooling elements (18) are each substantially plate-shaped. [4] Drive battery assembly (10) according to one of the preceding claims, characterized by that the cooling device (16) has at least four cooling elements (18) which in particular have a width between 10 mm and 40 mm, preferably between 15 mm and 30 mm. [5] Drive battery assembly (10) according to one of the preceding claims, characterized by that the cooling fluid flows through the channels (20) of a cooling element (18) with the same flow direction. [6] Drive battery assembly (10) according to one of the preceding claims, characterized by that cooling elements (18) are provided in pairs through which the flow direction is the same. [7] Drive battery assembly (10) according to one of the preceding claims, characterized bythat the cooling elements (18) are pressed between the battery modules (12, 14). [8] Drive battery assembly (10) according to claim 7, characterized by that the battery modules (12, 14) are coupled to one another via at least one fixing element (32). [9] Drive battery assembly (10) according to claim 8, characterized by that at least one spring element (34) is provided in the force flow path between the battery modules (12, 14) and the fixing element (32), so that the battery modules (12, 14) are subjected to a spring force against one another. [10] Drive battery assembly (10) according to one of the preceding claims, characterized by that the cooling elements (18) are flexible.

Images