Heat exchanger

Abstract

The invention relates to a heat exchanger, in particular in the form of a battery cooling device for an electrically driven battery module on an electric vehicle, the heat exchanger having a cooling circuit for circulating a temperature control fluid, the cooling circuit being formed between two plates which are connected to each other in regions by means of roll-bonding, the plates are integrally connected in a joining region and are widened in unconnected hollow regions to form a cooling circuit, in which flow elements, which are surrounded by flow on all sides and influence the flow of the temperature control fluid through the cooling circuit, are formed by the joining region.

Description

Technical Field

[0001] The present invention relates to a heat exchanger, particularly as a battery cooling device for an electrically driven battery module in an electric vehicle, wherein the heat exchanger has a cooling circuit for circulating hot fluid, wherein the cooling circuit is formed between two plates that are regionally connected by roll forming, wherein the plates are connected to each other in the connecting region and extended in the unconnected hollow region to form the cooling circuit, wherein a flow element surrounded by flow on all sides is formed by the connecting region, the flow element influencing the flow of hot fluid through the cooling circuit. Background Technology

[0002] Electric vehicles include, among other things, an electric motor as a drive source, which is electrically connected to a battery module as an energy storage medium. In drive mode, the motor converts electrical energy into mechanical energy to propel the electric vehicle. The battery module, also known as a battery or accumulator, is typically cooled by a battery cooling system.

[0003] EP3625824A1 relates to a radiator comprising a substantially planar solid plate having a plurality of fluid flow channels adapted to guide coolant from an inlet to an outlet of the plate. The plurality of channels include at least two main channels interconnected by at least a plurality of bridging channels. The plurality of channels do not branch further between their respective attachment points to the main channels. The main channels are interconnected by at least a plurality of bridging channels, which do not branch further between their respective attachment points to the main channels. The bridging channels have a cross-section that is locally increased in the flow direction, and downstream of the locally increased cross-section, the bridging channels have a locally decreased cross-section in the flow direction.

[0004] US11583929B2 discloses a method for manufacturing a cooling plate, wherein a fluid circuit is formed on a build surface by layering build materials. The fluid circuit includes a plurality of peripheral walls, each of which at least partially defines a main channel, wherein one of the peripheral walls is longitudinally configured to include an opening configured to allow excess build material to pass through. A central wall of the fluid circuit at least partially defines the main channel and a plurality of secondary channels in fluid communication with the main channel. The process also involves removing excess build material through the openings.

[0005] The paper "Industrial application of topology optimization for forced convection based on Darcy flow," published in *Structural and Multidisciplinary Optimization*, Vol. 65, 2022, by Springer-Verlag, discusses the design of flow channel layouts, where a basic layout is created through topology optimization. Cooling of an automotive battery pack is shown as an application example. Cooling is achieved by the flow of liquid through cooling channels formed by roll-forming composites (composite processes). This manufacturing process enables complex channel patterns. The temperature on the battery module is optimized to have a uniformly low value while minimizing mechanical losses in the flow.

[0006] DE102021122913A1 discloses a battery cooling device for an electrically driven battery module in an electric vehicle, wherein the battery cooling device forms a substantially closed flow space for circulating hot fluid, and a plurality of flow elements are arranged in the flow space, the flow elements influencing the flow of hot fluid through the flow space. The flow space is formed between two plates joined together in certain regions by roll forming, wherein the plates are connected to each other in the connecting regions and expanded in the unconnected hollow regions to form the flow space, wherein the flow elements are formed by the connecting regions.

[0007] The design freedom offered by the roll forming process could not be fully realized by using simple, geometrically idealized, and repetitive channel structures. Summary of the Invention

[0008] The objective of this application is to improve the thermal and / or hydraulic performance of heat exchangers by utilizing the design freedom of roll cladding.

[0009] This objective is achieved by the heat exchanger according to claim 1. Further embodiments and further developments are the subject of the dependent claims.

[0010] A heat exchanger, specifically designed as a battery cooling device for electrically driven battery modules in electric vehicles, has a cooling circuit for circulating hot fluid. The cooling circuit is formed between two plates joined together in regions by roll forming, wherein the plates are materially bonded together in the connecting region and extend into an unconnected hollow region to form the cooling circuit. Flow elements, surrounded by flow on all sides, are formed by the connecting regions. These flow elements influence the flow of hot fluid through the cooling circuit and define the channel pattern of the cooling circuit. The flow elements include at least one elongated wall with an aspect ratio greater than three and at least one point structure with an aspect ratio not greater than three. The main portions of the flow elements each have a singular and asymmetrical shape.

[0011] The advantage of the asymmetric and monomorphic shape of the flow elements lies in the formation of channel patterns that are optimized in terms of thermal and / or hydraulic performance and deviate from standard shapes. Production via roll forming allows for design freedom, enabling optimized biomimetic channel patterns with a mixture of elongated walls and point structures. Most of the flow elements have a monomorphic shape. Therefore, a single flow element is unique and will not appear twice in the channel pattern. Point structures with an aspect ratio not greater than three are also referred to as recesses. In asymmetric shapes, the aspect ratio is the ratio of the longest extension to the smallest extension of the point structure in the plane defined by the plate. In particular, point structures can have an aspect ratio less than two, and particularly preferably less than 1.5. The aspect ratio of the elongated walls is calculated in the same manner as that of the point structures. The applications of the heat exchanger are not limited to battery cooling devices. The heat exchanger can also be used in other cooling and air conditioning devices, such as in refrigerators or solar collectors. For the purposes of this invention, the channel pattern should be understood as the structure of the entire cooling circuit characterized by the shape and position of the point structures and elongated walls. In particular, the channel pattern does not form a single flow path, but rather a flow path that branches out and then re-converges.

[0012] A cooling circuit is formed between two plates bonded in regions by roll bonding, wherein the plates are material-bonded in the bonded region and extend into an unbonded hollow region, where flow elements are formed by the bonded region. Roll bonding can also be called roll-bonding. Material bonding in the hollow region is avoided by applying a coating before roll bonding. The hollow region between the plates is extended, for example, by inflating the unbonded region between the plates with compressed air. The hollow region can extend to one side of one plate or to both sides of both plates. In both cases, the heat exchanger, as a battery cooling device, can have a flat contact surface for the battery module.

[0013] As a manufacturing process for producing heat exchangers, roll forming or rolling compounding offers various advantages. Depending on the application, a wide range of aluminum alloys, from soft to high strength, can be used. Higher grades result in strength advantages, which have a positive impact on impact behavior. Depending on the material, thickness variations, and geometry, roll forming enables very high burst pressures exceeding 10 bar and / or up to 20 bar. Another 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 heat exchangers; they can be designed as a single-piece unit with only one upper and lower plate, or as a multi-piece unit with a set of upper and lower plates. Cooling circuits can be formed on one or both sides. For connection technologies, steel-hybrid structures can also be used, for example, by using friction-welded elements and / or adhesives. Cooling circuits created by air filling have clean inner surfaces, which has a beneficial effect on service life.

[0014] According to one embodiment, the main portion of the channel pattern is defined to have an asymmetrical shape. This means that not only are individual flow elements themselves asymmetrical, but also a large portion of the channel pattern is asymmetrical, allowing for free design and optimization. Specifically, within the main portion of the channel pattern, any selected segment of the channel pattern can have a single shape, i.e., unique within the channel pattern. The main portion of the channel pattern is understood to occupy more than half of the surface of the plane formed by the plate. In particular, at least 90% of the area-based portion of the channel pattern can have an asymmetrical shape, and randomly selected segments of the channel pattern within this portion can have a single shape. Typically, the entire channel pattern can exhibit the aforementioned asymmetry and uniformity. However, regular channel segments can be provided, particularly in the inlet and outlet areas. The randomly selected segments can be circular, square, or irregular in shape, and cover at least 5% of the surface occupied by the channel pattern, and have a maximum aspect ratio of five.

[0015] According to a further embodiment, the edge of the flow element is defined to form a continuous, smooth curve in the plane defined by the plate. The edge is mathematically continuous, meaning it has a uniform curvature without inflection points or sharp edges. Specifically, the direction of the edge of the main portion of the flow element may have more than three inflection points, where an inflection point, in a mathematical sense, represents a change in the direction of curvature. The curve formed by the edge of the main portion of the flow element may have a larger number of inflection points, for example, at least ten, at least 30, or at least 100. The description of a large number of inflection points describes an irregular curve of the edge, where the inflection points are not equidistant and the extreme points of the curve between two adjacent inflection points have different heights.

[0016] According to a further embodiment, the cross-sectional area of ​​the channel is specified to vary transversely to the flow direction of the channel segment of the channel pattern, wherein the ratio of the maximum to the minimum cross-sectional area of ​​the channel segment can be at least 1.5, and the ratio can be as high as ten. Specifically, the channel cross-sectional area can vary continuously over the main portion of the overall length of the channel pattern, i.e., it is not constant. The width of the channel segment of the channel pattern transversely to the flow direction can vary in the flow direction, wherein the ratio of the maximum to the minimum width of the channel segment can be at least 1.5, and the ratio can be as high as four. Specifically, the width can vary continuously over the main portion of the overall length of the channel pattern, i.e., it is not constant. Alternatively or additionally, the height of the channel segment of the channel pattern transversely to the flow direction can vary in the flow direction, wherein the ratio of the maximum to the minimum height of the channel segment can be at least 1.5, and the ratio can be as high as five. Specifically, the height can vary continuously over the main portion of the overall length of the channel pattern, i.e., it is not constant. The flank angle and / or flank radius of the channel section in the channel pattern can vary in the flow direction.

[0017] According to a further embodiment, the channel pattern is defined to have at least one section with only dot structures arranged therein. In particular, the channel pattern may have at least eight dot structures per square meter. Alternatively or additionally, the average aspect ratio of the elongated walls may be at least seven, wherein the average aspect ratio is calculated as the average of the aspect ratios of all the elongated walls of the channel pattern.

[0018] According to a further embodiment, the channel pattern is specified to have a channel area, wherein the ratio between the channel area and the surface of the battery module to which heat input is introduced is between 60% and 95%, particularly between 80% and 95%, and preferably between 90% and 95%. The channel area is the area occupied by the channel pattern in the plane defined by the plate.

[0019] According to a further embodiment, the cooling circuit includes at least one first region having channel segments and at least one second region having channel segments, wherein the height of the channel segments in the first region is greater than the height of the channel segments in the second region, and at least one second region coincides with a surface from which heat input is introduced from the battery module. The cooling circuit may include at least one third region having channel segments of different heights, wherein at least one third region is disposed between at least one first region and at least one second region. Attached Figure Description

[0020] An embodiment of the heat exchanger is explained below with reference to the accompanying drawings. In the drawings: Figure 1An embodiment of the heat exchanger is shown; Figure 2 It shows that according to Figure 1 A perspective view of an embodiment; Figure 3 A cross-section of an exemplary channel pattern is shown; Figure 4 A longitudinal section of an exemplary channel pattern with a height range is shown; Figures 5 to 10 Further embodiments of the channel pattern are shown; Figure 11 A further embodiment of a channel pattern with a height range is shown; Figure 12 A longitudinal section of an exemplary channel pattern with a height range is shown; Figure 13 A cross-section of an exemplary channel pattern is shown. Detailed Implementation

[0021] Figure 1 A heat exchanger is shown in a perspective view as a battery cooling device for an electrically driven battery module in an electric vehicle. The battery cooling device has a cooling circuit 1 for circulating hot fluid, which is formed between two plates 23, 25 connected to each other in a region by roll forming. The plates 23, 25 are materially bonded to each other in a connecting region 3 and extend into an unconnected hollow region 4 to form the cooling circuit 1. Flow elements 5, 6 and wall regions 17, surrounded by flow on all sides, are formed by the connecting region 3. The flow elements 5, 6 influence the flow of hot fluid through the cooling circuit 1 and define the channel pattern of the cooling circuit. The cooling circuit 1 is hermetically sealed except for the connection portion 2 leading to the outside and serving as a supply and return line for the hot fluid. One of the outwardly extending connection portions 2 is located below the battery cooling device and is therefore not visible.

[0022] Figure 2 It shows that according to Figure 1 The channel pattern of the embodiment. Flow elements 5 and 6 include a plurality of elongated walls 5 with an aspect ratio greater than 3 and a plurality of point structures 6 with an aspect ratio not greater than 3. The main portions of flow elements 5 and 6 have a single and asymmetrical shape for each flow element 5 and 6. For clarity, only some of the elongated walls 5 and point structures 6 are indicated by reference numerals. The channel pattern has a plurality of segments 10 in which only point structures 6 are arranged. Figure 2 The channel patterns shown exhibit irregular biomimetic structures, most of which cannot be assembled from standard design elements. For example, the channel width is not less than 10 mm. In particular, the minimum channel width can be one-quarter of the maximum channel width. The channel patterns have only continuous boundaries, so there are no sharp edges on the flow elements 5 and 6.

[0023] The channel pattern illustrates an irregular biomimetic channel structure with significantly varying channel widths. Slender walls 5 and point structures 6 are combined. The channel pattern has multiple branching points 7 that are not Y-shaped, meaning at least four branches 8 converge at these branching points 7. The branches 8 are not distinguished based on the inflow or outflow direction. Therefore, the connecting portion 2 is also considered a branch 8. To facilitate forward and return flow, further connecting portions are arranged in planes perpendicular to plates 23 and 25; these connecting portions are not visible here. The channel pattern as a whole has an asymmetrical shape. Furthermore, any segment of the channel pattern has a single shape, meaning it does not repeat along the channel pattern.

[0024] In an exemplary embodiment, a total of ten rectangular surfaces 11 are marked for the mounting area of ​​the battery module. The channel pattern occupies the channel area, wherein the ratio between the channel area and the surface 11 where the battery module introduces heat input is between 60% and 95%. Due to the full utilization of design freedom, the proportion of surface covered by the channel segments can be particularly large through the biomimetic channel pattern. For example, a fastening region 16 exists outside the surface 11, in which the proportion is significantly lower.

[0025] Figure 3 A cross-section of a channel segment of an exemplary channel pattern is shown. Two plates 23, 25 are connected to each other in a connecting region 3. The upper plate 23 extends in an unconnected hollow region 4. The edge regions 9 of the flow elements 5, 6 formed by the connecting region 3 form continuous, smooth curves in the plane defined by plates 23, 25. Figure 3 In the diagram, the flow direction is perpendicular to the plane shown. The cross-sectional area of ​​the channel segment transverse to the flow direction can vary along the channel pattern in the flow direction, wherein the ratio of the maximum to the minimum cross-sectional area of ​​the channel segment can be at least 1.5. For example, the width w can vary transversely to the flow direction of the channel segment. Additionally or alternatively, the height h of the channel segment of the channel pattern can vary transversely to the flow direction of the channel segment. Results show that the flank angle α and / or flank radius r of the channel segment of the channel pattern can also vary in the flow direction.

[0026] Figure 4 A longitudinal section of a channel segment of an exemplary channel pattern is shown, wherein the height h in the first region 12 is higher than the height h in the second region 14. In a third region 15 between regions 12 and 14, the height h increases continuously. The internal channel height h varies between the two levels and has a continuous connection, which can also have a non-linear variation. Alternatively, there may be no constant height, but rather a continuously varying height.

[0027] Figures 5 to 10 Further exemplary channel patterns of other embodiments are shown.

[0028] Figure 5 A cooling circuit 1 with oblique flow is shown, having a connection 2 for the supply line in the lower left and another connection 2 for the return line in the upper right. The channel pattern is shown as a point structure 6 with more elongated walls 5.

[0029] Figure 6 A vertically flowing cooling circuit 1 is shown, with a connection 2 for the supply line at the lower left and another connection 2 for the return line at the upper left. The channel pattern is shown as an elongated wall 5 with more than one point structure 6.

[0030] Figure 7 A section of another cooling circuit 1 is shown, its channel pattern shown as elongated walls 5 with more point structures 6, some of which are connected to fastening regions 16.

[0031] Figure 8 This shows a section of another cooling circuit 1, whose channel pattern has a larger... Figure 7 The cooling circuit shown has a longer, slender wall 5. The shorter, slender wall 5 is connected to the fastening area 16.

[0032] Figure 9 A section of another cooling circuit 1 is shown, whose channel pattern also features elongated walls 5 and dotted structures 6.

[0033] Figure 10 A section of another cooling circuit 1 is shown, whose channel pattern is also quite slender with walls 5 and dotted structures 6.

[0034] Figure 11 A further embodiment with a channel pattern having a height range is shown. The cooling circuit 1 has a first region 12 with channel segments and a second region 14 with channel segments, wherein the height of the channel segments in the first region 12 is greater than the height of the channel segments in the second region 14. The second region 14 is adjacent to the surface 11 where the battery module introduces heat input (…). Figure 2 The third region 15, with a channel section of variable height, is arranged between the first region 12 and the second region 14. A larger channel height is advantageous in regions where no heat is introduced, where only low pressure loss should be maintained and heat contribution negligible. A large channel cross-section with a larger channel height is particularly suitable for this purpose. This is particularly suitable for the region between the connection of the supply and return lines and the surface 11 with heat input, and the region between the surfaces 11 used for the battery module. The third region 15 is provided between the first region 12 and the second region 14, each with a constant height, as a transition region with a continuously varying channel height. In the second region 14 with heat input, a lower channel height can be advantageous to increase fluid velocity and improve heat dissipation.

[0035] Figure 11 The first region 12 on the left has a connection 2 for flow, and the supply channel leading to the surface 11 with heat input has a large channel height, for example, an internal channel height of 3.5 mm. The subsequent third region 15 is a transition region with continuously varying channel heights. The second region 14 on the left is the module surface 11 with a battery module, i.e., with heat input, and has a lower channel height, for example, an internal channel height of 1.5 mm. The subsequent third region 15 is a transition region with continuously varying channel heights. The central first region 12 is a connection region between the surfaces 11 with heat input, and has a large channel height, for example, an internal channel height of 3.5 mm. The subsequent third region 15 is again a transition region with continuously varying channel heights. The second region 14 on the right is the module surface 11 with a battery module, i.e., with heat input, and has a lower channel height, for example, an internal channel height of 1.5 mm. The subsequent third region 15 is a transition region with continuously varying channel heights. Figure 11 The first region 12 on the right side has a connection 2 for the return line and a supply channel with a large channel height from the surface 11 with heat input, for example, the internal channel height is 3.5 mm.

[0036] Figure 12 A longitudinal section of an exemplary channel pattern with varying height h between plates 23 and 25 is shown. The height h varies continuously over the channel segment shown, meaning it is not constant over any range, as indicated by the two heights h shown.

[0037] Figure 13 A cross-section of a channel segment of an exemplary channel pattern is shown. Two plates 23, 25 are materially bonded together in the connection region 3. In the illustrated exemplary embodiment, both plates 23, 25 extend into the unconnected hollow region 4.

[0038] List of reference numerals

[0039] 1 Cooling circuit

[0040] 2. Connecting part

[0041] 3 Connecting regions

[0042] 4. Hollow Area

[0043] 5. Flow element, slender wall

[0044] 6. Flow element, point structure

[0045] 7 branch points

[0046] 8 branches

[0047] 9. Edge

[0048] 10 Only sections with some structure are arranged.

[0049] 11 Surfaces that introduce heat input

[0050] 12 First Region

[0051] 14 Second Region

[0052] 15 Third Region

[0053] 16 Fastening Area

[0054] 17 Wall Area

[0055] 23 boards

[0056] 25 boards

Claims

1. A heat exchanger, particularly as a battery cooling device for an electrically driven battery module in an electric vehicle. in, The heat exchanger has a cooling circuit (1) for circulating hot fluid, wherein the cooling circuit is formed between two plates connected to each other in a region by roll forming, wherein the plates (23, 25) are materially bonded together in a connecting region (3) and extend in an unconnected hollow region (4) to form the cooling circuit (1), wherein flow elements (5, 6) are formed by the connecting region (3), the flow elements influencing the flow of the hot fluid through the cooling circuit (1) and defining the channel pattern of the cooling circuit, wherein the flow elements include at least one elongated wall (5) with an aspect ratio greater than three and at least one point structure (6) with an aspect ratio not greater than three. Its features are, The main part of the flow element has a single and asymmetrical shape for each of the flow elements (5, 6).

2. The heat exchanger according to claim 1, characterized in that, The channel pattern has at least one branch point (7) with at least four branches (8).

3. The heat exchanger according to any one of the preceding claims, characterized in that, The main part of the channel pattern has an asymmetrical shape.

4. The heat exchanger according to any one of the preceding claims, characterized in that, In the main part of the channel pattern, any selected segment of the channel pattern has a single shape.

5. The heat exchanger according to any one of the preceding claims, characterized in that, The edges (9) of the flow elements (5, 6) have a continuous smooth curve in the plane defined by the plate.

6. The heat exchanger according to claim 5, characterized in that, The curve of the edge (9) of the main part of the flow element (5, 6) has more than three inflection points.

7. The heat exchanger according to any one of the preceding claims, characterized in that, The cross-sectional area of ​​the channel changes transversely to the flow direction of the channel segment of the channel pattern.

8. The heat exchanger according to claim 7, characterized in that, The ratio of the maximum channel cross-sectional area to the minimum channel cross-sectional area of ​​the channel section is at least 1.

5.

9. The heat exchanger according to any one of the preceding claims, characterized in that, The width (w) varies transversely to the flow direction of the channel segment of the channel pattern in the flow direction.

10. The heat exchanger according to claim 9, characterized in that, The ratio of the maximum width to the minimum width of the channel section is at least 1.

5.

11. The heat exchanger according to any one of the preceding claims, characterized in that, The height (h) varies transversely to the flow direction of the channel segment of the channel pattern in the flow direction.

12. The heat exchanger according to claim 11, characterized in that, The ratio of the maximum height to the minimum height of the channel segment in the channel pattern is at least 1.

5.

13. The heat exchanger according to any one of the preceding claims, characterized in that, The flank angle (α) and / or flank radius (r) of the channel section of the channel pattern vary along the flow direction.

14. The heat exchanger according to claim 13, characterized in that, The channel pattern has at least one segment (10) with only point structures (6) arranged.

15. The heat exchanger according to any one of the preceding claims, characterized in that, The channel pattern has at least eight point structures per square meter (6).

16. The heat exchanger according to any one of the preceding claims, characterized in that, The average aspect ratio of the slender wall (5) is at least seven.

17. The heat exchanger according to any one of the preceding claims, characterized in that, The channel pattern occupies the channel area, wherein the ratio of the channel area to the surface (11) on which the battery module introduces heat input is between 60% and 95%, particularly between 80% and 95%, and preferably between 90% and 95%.

18. The heat exchanger according to any one of the preceding claims, characterized in that, The cooling circuit (1) has at least one first region (12) with channel segments and at least one second region (14) with channel segments, wherein the height of the channel segments in the first region (12) is greater than the height of the channel segments in the second region (14), and wherein the at least one second region coincides with the surface (11) from which heat input is introduced from the battery module.

19. The heat exchanger according to claim 18, characterized in that, The cooling circuit (1) has at least one third region (15) with a channel section 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).

Images