Heat exchanger

Abstract

Heat exchanger, in particular as a battery cooling device for an electric battery module of an electric drive on an electric vehicle, wherein the heat exchanger has a cooling circuit for circulating a temperature control fluid, wherein the cooling circuit is formed between two plates that are partially connected to each other by roll cladding, wherein the plates are materially bonded in bonded areas and are expanded in unconnected hollow areas to form the cooling circuit, wherein flow elements are formed by the bonded areas on all sides, which influence a flow of the temperature control fluid through the cooling circuit.

Description

[0001] The invention relates to a heat exchanger, in particular as a battery cooling device for an electric battery module of an electric drive on an electric vehicle, wherein the heat exchanger has a cooling circuit for circulating a temperature control fluid, wherein the cooling circuit is formed between two plates that are partially connected to one another by roll bonding, wherein the plates are materially connected in bonded regions and are expanded in unconnected hollow regions to form the cooling circuit, wherein flow elements that are flowed around on all sides are formed by the bonded regions and influence a flow of the temperature control fluid through the cooling circuit.

[0002] An electric vehicle includes, among other things, an electric motor as the power source, which is electrically connected to electric battery modules as storage devices. In drive mode, the electric motor converts electrical energy into mechanical energy to power the electric vehicle. The electric battery modules, also referred to simply as batteries or accumulators, are typically cooled by a battery cooling device.

[0003] EP 3 625 824 A1 relates to a heat sink comprising a substantially planar solid plate provided with a plurality of fluid flow channels, wherein the plurality of fluid flow channels are configured to conduct a coolant from an inlet to an outlet of the plate, wherein the plurality of channels comprises at least two main channels interconnected by at least a plurality of bridging channels which do not branch further between their respective attachment points to the main channels, wherein the bridging channels have a cross-section which locally increases in the flow direction, and wherein the bridging channels have a cross-section which locally decreases in the flow direction downstream of the local cross-sectional increase.

[0004] US 11 583 929 B2 discloses a method for manufacturing a cooling plate, in which a fluid circuit is formed on a build surface in layers from a build material. The fluid circuit comprises a plurality of peripheral walls, each of the plurality of peripheral walls at least partially defining a primary channel, one of the peripheral walls being longitudinally formed to include openings configured to allow excess build material to pass therethrough. A central wall of the fluid circuit at least partially defines the primary channel and a plurality of secondary channels in fluid communication with the primary channel. The method further comprises removing excess build material through the openings.

[0005] The article "Industrial application of topology optimization for forced convection based on Darcy flow" in Structural and Multidisciplinary Optimization (2022) 65: 265, Springer-Verlag, concerns the design of a flow channel layout, with a baseline layout created through topology optimization. The cooling of automotive battery packs is presented as an application example. Cooling is achieved by fluid flow through cooling channels manufactured by roll bonding. This manufacturing process enables complex channel patterns. The temperature on the battery modules is optimized to maintain a consistently low value while simultaneously minimizing mechanical losses in the flow.

[0006] DE 10 2021 122 913 A1 discloses a battery cooling device for an electric battery module of an electric drive on an electric vehicle. The battery cooling device forms a substantially closed flow space for circulating a temperature control fluid, and a plurality of flow elements are arranged in the flow space, influencing the flow of the temperature control fluid through the flow space. The flow space is formed between two plates that are partially joined to one another by roll bonding. The plates are integrally connected in bonded regions and expanded in unconnected hollow regions to form the flow space. The flow elements are formed by the bonded regions.

[0007] The design freedom offered by the roll bonding manufacturing process is not fully exploited by the use of simple, geometrically idealized and recurring channel structures.

[0008] One object of the application may be to improve a heat exchanger by exploiting the design freedom of roll bonding with regard to its thermal and / or hydraulic properties.

[0009] The object is achieved by a heat exchanger according to claim 1. Further embodiments and developments can be found in the subclaims.

[0010] The heat exchanger, which is designed in particular as a battery cooling device for an electric battery module of an electric drive on an electric vehicle, has a cooling circuit for circulating a temperature control fluid. The cooling circuit is formed between two plates that are partially joined to one another by roll bonding, wherein the plates are integrally connected to one another in bonded regions and expanded in unconnected hollow regions to form the cooling circuit. Flow elements surrounded by flow on all sides are formed by the bonded regions, which influence the flow of the temperature control fluid through the cooling circuit and determine a channel path of the cooling circuit, wherein the flow elements comprise at least one elongated wall with an aspect ratio greater than three and at least one point structure with an aspect ratio of up to three.A predominant proportion of the flow elements have a singular and asymmetric shape of the respective flow element.

[0011] One advantage of the asymmetric and singular shape of the flow elements is that it creates a channel layout that is optimized in terms of thermal and / or hydraulic properties and deviates from standard shapes. Production by roll bonding allows design freedom, enabling an optimized, bionic channel layout with a blend of elongated walls and dot structures. The majority of the flow elements have a singular shape. This means that each individual flow element is unique and does not occur a second time within the channel. The dot structure, with an aspect ratio of up to three, is also known as a dimple. The aspect ratio of the asymmetric shape is the ratio of the longest dimension to the smallest dimension of the dot structure in the plane defined by the plates.In particular, the dot structure can have an aspect ratio of less than two, and more preferably an aspect ratio of less than 1.5. The aspect ratio of the elongated wall is calculated in the same way as that of the dot structure. The use of the heat exchanger is not limited to battery cooling devices. The heat exchanger can also be used in other cooling and air conditioning devices, for example, in refrigerators or solar panels.

[0012] The cooling circuit is formed between two plates that are partially joined by roll bonding, with the plates being integrally connected in bonded areas and expanded in unconnected hollow areas, with the flow elements being formed by the bonded areas. Roll bonding can also be referred to as roll bonding. The integral connection in the hollow areas is avoided by applying a coating before roll bonding. The hollow areas between the plates are expanded, for example, by introducing compressed air into the non-integrally connected areas between the plates. The hollow areas can be expanded on one side in one of the plates or on both sides in both plates. In both cases, the heat exchanger as a battery cooling device can have a flat contact surface for the battery modules.

[0013] Roll bonding, or roll cladding, as a manufacturing process for heat exchangers offers various advantages. Depending on the application, various aluminum alloys from soft to high-strength can be used. Higher grades offer a strength advantage, which has a positive effect on crash behavior. Depending on the material, thickness variation, and geometry, roll bonding enables very high burst pressures of over 10 bar and / or up to 20 bar. A further advantage is that the strength of the heat exchanger is independent of temperature. Furthermore, there is a high degree of flexibility in the design of the heat exchanger, which can be constructed as a single piece with just an upper and lower plate, or as a multi-piece assembly comprising a group of upper and lower plates. The cooling circuit can be incorporated on one or both sides.A composite steel construction is also possible in the joining technology, for example, through the use of friction welding elements and / or adhesives. The cooling circuit created by the expansion process has a clean inner surface, which has a positive effect on service life.

[0014] According to one embodiment, a predominant portion of the total length of the channel path has an asymmetric shape. Thus, not only are the individual flow elements asymmetrical, but so is the predominant portion of the channel path, allowing it to be advantageously freely designed and optimized. In particular, an arbitrarily selected section of a predominant portion of the channel path can have a singular shape, i.e., not be unique within the channel path.

[0015] According to a further embodiment, an edge region of the flow elements has a continuous, continuous profile in a plane defined by the plates. The edge region is continuous in the mathematical sense, meaning that the edge region has a homogeneous curvature, without any kink or sharp edge.

[0016] According to a further embodiment, it is provided that a channel cross-sectional area transverse to a flow direction of a channel section of the channel course varies in the flow direction, wherein a ratio of a largest channel cross-sectional area to a smallest channel cross-sectional area of ​​the channel section can be at least 1.5, wherein the ratio of the largest channel cross-sectional area to the smallest channel cross-sectional area can be up to ten. The channel cross-sectional area can, in particular, be constantly varying, i.e., not constant, over a predominant part of the total length of the channel course. A width transverse to a flow direction of a channel section of the channel course can vary in the flow direction, wherein a ratio of a largest width to a smallest width of the channel section can be at least 1.5, wherein the ratio of the largest width to the smallest width can be up to four.The width can, in particular, vary constantly over a predominant part of the total length of the channel, i.e., not be constant. Alternatively or additionally, a height transverse to a flow direction of a channel section of the channel can vary in the flow direction, wherein a ratio of a greatest height to a smallest height of the channel section of the channel can be at least 1.5, wherein the ratio of the greatest height to the smallest height can be up to five. The height can, in particular, vary constantly over a predominant part of the total length of the channel, i.e., not be constant. A flank angle and / or a flank radius of a channel section of the channel can vary in the flow direction.

[0017] According to a further embodiment, the channel path has at least one section in which exclusively point structures are arranged. The channel path can, in particular, have at least eight point structures per square meter. Alternatively or additionally, the aspect ratio of the elongated walls can average at least seven, with the average being calculated as the mean of the aspect ratios of all elongated walls of the channel path.

[0018] According to a further embodiment, it is provided that the channel course has a channel area, wherein a ratio of the channel area to an area over which heat power is introduced by the electric battery module is between 60 and 95 percent, in particular between 80 and 95 percent and preferably between 90 and 95 percent.

[0019] According to a further embodiment, the cooling circuit comprises at least one first region with channel sections and at least one second region with channel sections, wherein a height of the channel sections in the first region is greater than a height of the channel sections in the second region, and wherein the at least one second region corresponds to an area over which heat power is introduced by the electric battery module. The cooling circuit can comprise at least one third region with channel sections of varying height, wherein the at least one third region is arranged between the at least one first region and the at least one second region.

[0020] Embodiments of the heat exchanger are explained below with reference to the accompanying drawings. Herein: Fig. 1 an embodiment of the heat exchanger; Fig. 2 a channel course of the embodiment according to Fig. 1; Fig. 3 a cross-section of an exemplary channel course; Fig. 4 a longitudinal section of an exemplary channel course with height ranges; Fig. 5 to 10 each show channel courses of further embodiments; Fig. 11 shows a channel course of a further embodiment with height ranges; Fig. 12 a longitudinal section of an exemplary channel course with varying height; Fig. 13 a cross-section of an example channel course.

[0021] In the Fig. 1 shows a perspective view of a heat exchanger as a battery cooling device for an electric battery module of an electric drive on an electric vehicle. The battery cooling device has a cooling circuit 1 for circulating a temperature control fluid, wherein the cooling circuit 1 is formed between two plates 23, 25 that are partially connected to one another by roll bonding. The plates 23, 25 are integrally connected to one another in bonding regions 3 and are expanded in unconnected hollow regions 4 to form the cooling circuit 1. Flow elements 5, 6 and wall regions 17, which are surrounded by flow on all sides, are formed by the bonding regions 3, wherein the flow elements 5, 6 influence the flow of the temperature control fluid through the cooling circuit 1 and determine the channel path of the cooling circuit.Apart from the external connections 2, which serve as the inlet and return lines for the temperature control fluid, the cooling circuit 1 is sealed gas-tight. One of the external connections 2 is located below the battery cooling device and is therefore not visible.

[0022] The channel course of the embodiment according to Fig. 1 is in the Fig. 2. The flow elements 5, 6 comprise a plurality of elongated walls 5 with an aspect ratio greater than three and several point structures 6 with an aspect ratio of up to three. A predominant proportion of the flow elements 5, 6 has a singular and asymmetrical shape of the respective flow element 5, 6. For the sake of clarity, only some of the elongated walls 5 and the point structures 6 are provided with exemplary reference numerals along the channel course. The channel course has several sections 10 in which exclusively point structures 6 are arranged. Fig. The channel layout shown in Figure 2 exhibits irregular, bionic structures that cannot be assembled from standard design elements. A channel width of, for example, 10 millimeters is not exceeded. The smallest channel width can, in particular, be a quarter of the maximum channel width. The channel layout features exclusively continuous boundaries, meaning there are no sharp edges at the flow elements 5 and 6.

[0023] The channel course displays irregular, bionic channel structures with significantly varying channel widths. Elongated walls 5 and point structures 6 are mixed. The channel course has several branching points 7 that do not have a Y-shape, i.e., at which at least four branching branches 8 meet. The branching branches 8 are not differentiated according to inflow or outflow direction. Therefore, a connection 2 also counts as a branching branch 8. To form a supply and a return flow, another connection is arranged perpendicular to a plane of the plates 23, 25, which is not visible here. The channel course has an overall asymmetrical shape. Furthermore, any section of the channel course has a singular shape, i.e., it does not repeat itself along the channel course.

[0024] In the exemplary embodiment, a total of ten rectangular surfaces 11 mark the installation areas for battery modules. The channel layout occupies a channel area, with the ratio of the channel area to the area 11, through which heat output from the electric battery module is introduced, being between 60 and 95 percent. The proportion of the area covered by channel sections can be particularly large with the bionic-shaped channel layout, as the design freedom is fully utilized. Outside the surfaces 11, for example, fastening areas 16 are arranged, where the ratio is significantly lower.

[0025] In the Fig. Figure 3 shows a cross-section through a channel section of an exemplary channel path. The two plates 23, 25 are integrally connected to one another in the bonded regions 3. The upper plate 23 is widened in the unconnected hollow region 4. An edge region 9 of the flow elements 5, 6 formed by the bonded region 3 has a continuous, continuous path in the plane defined by the plates 23, 25. A flow direction is perpendicular to the drawing plane of the Fig. 3. A channel cross-sectional area transverse to the flow direction of the channel section can vary along the channel path in the flow direction, wherein a ratio of a largest channel cross-sectional area to a smallest channel cross-sectional area of ​​the channel section can be at least 1.5. For example, a width w can vary transversely to the flow direction of the channel section. Additionally or alternatively, a height h can vary transversely to the flow direction of the channel section of the channel path. This means that a flank angle α and / or a flank radius r of a channel section of the channel path can also vary in the flow direction.

[0026] In the Fig. Figure 4 shows a longitudinal section through a channel section of an exemplary channel path, with the height h being higher in a first region 12 than in a second region 14. The height h increases continuously across a third region 15 between regions 12 and 14. The inner channel height h varies here between two steps with a continuous connection, which, however, can also have a non-linear profile. It would also be possible for there to be no constant height, but rather a continuously varying height.

[0027] In the Fig. 5 to 10 show further exemplary channel courses of further embodiments.

[0028] The Fig. Figure 5 shows a diagonally flowing cooling circuit 1 with a connection 2 at the bottom left for the flow and another connection 2 at the top right for the return. The channel layout features more point structures 6 than elongated walls 5.

[0029] The Fig. Figure 6 shows a vertically flowing cooling circuit 1 with a connection 2 at the bottom left for the flow and another connection 2 at the top left for the return. The channel layout features more elongated walls 5 than point structures 6.

[0030] The Fig. 7 shows a section of a further cooling circuit 1, the channel course of which shows more elongated walls 5 than point structures 6, with some elongated walls 5 being connected to fastening areas 16.

[0031] The Fig. 8 shows a section of a further cooling circuit 1, the channel course of which has longer elongated walls 5, the cooling circuit according to Fig. 7. Shorter elongated walls 5 are connected to the fastening areas 16.

[0032] The Fig. 9 shows a section of another cooling circuit 1, the channel course of which has equally elongated walls 5 and point structures 6.

[0033] The Fig. 10 shows a section of another cooling circuit 1, the channel course of which also has equally elongated walls 5 and point structures 6.

[0034] In the Fig. 11 shows a channel layout of a further embodiment with height regions. The cooling circuit 1 has first regions 12 with channel sections and second regions 14 with channel sections, wherein a height of the channel sections in the first regions 12 is greater than a height of the channel sections in the second regions 14. The second regions 14 correspond to a surface 11 over which heat power is introduced from the electric battery module ( Fig. 2). Third regions 15 with channel sections of variable height are arranged between the first regions 12 and the second regions 14. Greater channel heights are useful in regions where no heat is introduced, since here only the pressure loss should be kept as low as possible, while the thermal contribution is negligible. For this purpose, large channel cross-sections due to high channel heights are particularly useful. This applies in particular to the areas of the supply and return connections up to the surfaces 11 of the heat introduction, as well as to the areas between the surfaces 11 with battery modules. Between the first regions 12 and the second regions 14, each with a constant height, lie the third regions 15 as transition regions with continuously varying channel heights. In the second regions 14 of the heat introduction, low channel heights can be advantageous in order to increase the fluid velocity and improve heat dissipation.

[0035] The first area 12 on the left in the Fig. 11 with the connection 2 for the flow and supply channels to the surfaces 11 of the heat input has a large channel height, for example an inner channel height of 3.5 mm. The adjoining third area 15 is a transition area with a continuously varying channel height. The left-hand second area 14 is a module area 11 with battery modules, i.e. with heat input, and has a lower channel height, for example an inner channel height of 1.5 mm. The adjoining third area 15 is a transition area with a continuously varying channel height. The middle first area 12 is a connecting area between the surfaces 11 of the heat input with a large channel height, for example an inner channel height of 3.5 mm. The adjoining third area 15 is again a transition area with a continuously varying channel height.The second right-hand area 14 is a module area 11 with battery modules, i.e., with heat input, and has a lower channel height, for example, an inner channel height of 1.5 mm. The adjoining third area 15 is a transition area with a continuously varying channel height. The first area 12 on the right in the . Fig. 11 with the connection 2 for the return and supply channels from the surfaces 11 of the heat input has a large channel height, for example an inner channel height of 3.5 mm.

[0036] In the Fig. Figure 12 shows a longitudinal section of an exemplary channel path between plates 23, 25 with varying height h. The height h varies continuously across the channel section shown, thus is not constant over any area, which is indicated by the two heights h shown.

[0037] In Fig.Figure 13 shows a cross-section through a channel section of an exemplary channel layout. The two plates 23, 25 are firmly bonded to one another in the bonding regions 3. In the illustrated embodiment, both plates 23, 25 are expanded in the unconnected hollow region 4. List of reference symbols 1 cooling circuit 2 connection 3 Network area 4 hollow areas 5 Flow element, elongated wall 6 Flow element, point structure 7 branching point 8 branching branch 9 Marginal area 10 Section in which only point structures are arranged 11 Area over which heat output is introduced 12 First area 14 Second area 15 Third Area 16 Mounting area 17 Wall area 23 plate 25 plate QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 625 824 A1

[0003] US 11 583 929 B2

[0004] DE 10 2021 122 913 A1

[0006] Cited non-patent literature

[0000] “Industrial application of topology optimization for forced convection based on Darcy flow” in Structural and Multidisciplinary Optimization (2022) 65: 265

[0005]

Claims

[1] Heat exchanger, in particular as a battery cooling device for an electric battery module of an electric drive on an electric vehicle, wherein the heat exchanger has a cooling circuit (1) for circulating a temperature control fluid, wherein the cooling circuit is formed between two plates that are partially connected to one another by roll bonding, wherein the plates (23, 25) are materially connected to one another in bonded regions (3) and are expanded in unconnected hollow regions (4) to form the cooling circuit (1), wherein flow elements (5, 6) are formed by the bonded regions (3) around which the fluid flows on all sides, which influence a flow of the temperature control fluid through the cooling circuit (1) and determine a channel course of the cooling circuit, wherein the flow elements comprise at least one elongated wall (5) with an aspect ratio greater than three and at least one point structure (6) with an aspect ratio of up to three, characterized by , that a predominant proportion of the flow elements has a singular and asymmetrical shape of the respective flow element (5, 6). [2] Heat exchanger according to claim 1, characterized by that the channel course has at least one branching point (7) with at least four branching branches (8). [3] Heat exchanger according to one of the preceding claims, characterized by that a predominant part of the total length of the canal has an asymmetric shape. [4] Heat exchanger according to one of the preceding claims, characterized by that any section of a predominant part of the total length of the channel has a singular shape. [5] Heat exchanger according to one of the preceding claims, characterized by that an edge region (9) of the flow elements (5, 6) has a continuously continuous course in a plane defined by the plates. [6] Heat exchanger according to one of the preceding claims, characterized by that a channel cross-sectional area varies transversely to a flow direction of a channel section of the channel course in the flow direction. [7] Heat exchanger according to claim 6, characterized by that the ratio of a largest channel cross-sectional area to a smallest channel cross-sectional area of the channel section is at least 1.

5. [8] Heat exchanger according to one of the preceding claims, characterized by that a width (w) transverse to a flow direction of a channel section of the channel course varies in the flow direction. [9] Heat exchanger according to claim 8, characterized by that the ratio of a maximum width to a minimum width of the channel section is at least 1.

5. [10] Heat exchanger according to one of the preceding claims, characterized bythat a height (h) transverse to a flow direction of a channel section of the channel course varies in the flow direction. [11] Heat exchanger according to claim 10, characterized by that the ratio of a maximum height to a minimum height of the channel section of the channel course is at least 1.

5. [12] Heat exchanger according to one of the preceding claims, characterized by that a flank angle (α) and / or a flank radius (r) of a channel section of the channel course varies in the flow direction. [13] Heat exchanger according to claim 12, characterized by that the channel course has at least one section (10) in which exclusively point structures (6) are arranged. [14] Heat exchanger according to one of the preceding claims, characterized by that the channel course has at least eight point structures (6) per square meter. [15] Heat exchanger according to one of the preceding claims, characterized bythat the aspect ratio of the elongated walls (5) is on average at least seven. [16] Heat exchanger according to one of the preceding claims, characterized by that the channel course occupies a channel area, wherein a ratio of the channel area to an area (11) over which heat power is introduced by the electric battery module is between 60 and 95 percent, in particular between 80 and 95 percent and preferably between 90 and 95 percent. [17] Heat exchanger according to one of the preceding claims, characterized byin that the cooling circuit (1) has at least one first region (12) with channel sections and at least one second region (14) with channel sections, wherein a height of the channel sections in the first region (12) is greater than a height of the channel sections in the second region (14) and wherein the at least one second region corresponds to a surface (11) via which heat power is introduced from the electric battery module. [18] Heat exchanger according to claim 17, characterized by that the cooling circuit (1) has at least one third region (15) with channel sections of variable height (h), wherein the at least one third region (15) is arranged between the at least one first region (12) and the at least one second region (14).

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