Cooling device

Abstract

Cooling device (2) for a battery (4) of a motor vehicle with a cooling channel (12) arranged between a surface (16) of the battery (4) to be cooled and a counter bearing (10, 22a), - wherein the surface to be cooled (16) and the counter bearing (10, 22a) are spaced apart from each other in a z-direction and the cooling channel (12) has a bottom surface (22a) oriented towards the counter bearing (10, 22a) and a top surface (20a) oriented towards the battery (4), - wherein the cooling channel (12) is formed in two parts with a first profile part (20) and a second profile part (22), - wherein the first profile part (20) having the cover surface (20a) is made of a metal, - wherein the second profile part (22) having the base surface (22a) is made of a plastic, and - wherein the cooling channel (12) can be expanded by at least a partial expansion of the second profile part (22) in the z-direction, so that the cooling channel (12) in the expanded state is in contact with the counter bearing (10, 22a) with its bottom surface (22a) and with the top surface (20a) with the surface (16) to be cooled.

Description

[0001] The invention relates to a cooling device for a motor vehicle battery with a cooling channel arranged between a surface of the battery to be cooled and a counter-support, wherein the surface to be cooled and the counter-support are spaced apart from each other in a z-direction and the cooling channel has a bottom surface oriented towards the counter-support and a top surface oriented towards the battery.

[0002] Electrically powered motor vehicles, such as electric or hybrid vehicles, typically include an electric motor that drives one or both axles. For the purpose of supplying electrical energy, the electric motor is typically coupled to an in-vehicle (high-voltage) battery as an electrical energy storage device. Such batteries are, for example, designed as accumulators, whereby several individual batteries or (battery) cells are typically connected modularly to form a common battery system (cell pack) in order to generate a sufficiently high operating voltage. Such a battery system is known, for example, from DE 10 2013 225 521 A1.

[0003] To improve range, lifespan, and available performance, it is necessary for each battery to maintain a certain operating temperature. It is essential that the individual batteries within the battery system maintain as similar a temperature as possible. In other words, a minimal temperature gradient within the battery system is desirable.

[0004] For this purpose, it is possible to thermally couple the battery, or each battery, to a cooling line or cooling channel of a vehicle cooling circuit. For this, for example, a surface of the battery to be cooled is brought into thermal contact with a contact surface or cover of the associated cooling channel, thereby enabling heat exchange between the battery and a cooling medium flowing through the cooling channel.

[0005] To ensure effective and consistent heat exchange, the cover surface of the cooling channel must be in contact with the battery surface to be cooled as closely and securely as possible. The cooling channel is typically located in a gap between the battery surface to be cooled and a fixed support. This support is, for example, a housing wall of the battery system's casing and / or an intermediate space between the surfaces to be cooled of two adjacent batteries.

[0006] The gap in this area can vary due to manufacturing tolerances within the battery system. In other words, the individual batteries in the system each have a different distance (in the z-direction) from their respective support. However, to ensure reliable and safe temperature control of the batteries, the cover surface must always be flush with the respective battery. Therefore, it is desirable to use cooling devices that compensate for or bridge such manufacturing tolerances.

[0007] To ensure consistent, even cooling, it is conceivable, for example, to bond the cooling channel to the battery surface to be cooled using a material-bonded connection in the area of ​​the cover. This connection can be achieved simply by adhesive bonding, although this requires a comparatively high manufacturing precision in the battery system. Furthermore, an adhesive layer between the cover and the surface to be cooled can impair heat transfer.

[0008] To compensate for manufacturing tolerances, a spring element can be positioned between the counter bearing and a base surface of the cooling channel. This spring element extends along the cooling channel like a rail. The spring element thus supports the cooling channel against the counter bearing. Due to the spring force, the cooling channel—and therefore the cover surface—is pressed against the surface of the battery to be cooled, so that manufacturing tolerances in the gap area can be at least partially compensated for by the spring's elasticity. A disadvantage of using such spring rails is that they increase the overall weight of the battery system, both due to the weight of the spring rail itself and the required rigidity of the supporting counter bearing. Furthermore, this increases the manufacturing costs of the battery system, as the spring rails represent additional components.Furthermore, a high degree of manufacturing accuracy of the cooling channel, the spring rail, and the counter bearing is necessary to ensure a homogeneous contact force.

[0009] From DE 10 2011 102 765 A1, a cooling device for a battery system is known in which a mounting foam is introduced as an expansion agent between a counter bearing and the bottom surface of a cooling channel. The foam-like expansion agent has a fixed volume in its initial state and a larger volume in its expanded state. The increase in volume of the expansion agent after its introduction results in a homogeneous contact pressure, which brings the cooling channel into contact with the battery system. However, the introduction and expansion of the expansion agent requires additional manufacturing steps during the production and / or assembly of the battery system, which adversely increases the assembly effort and manufacturing costs.

[0010] German patent application DE 10 2013 021 312 A1 describes a battery comprising a number of electrically series- and / or parallel-connected individual cells, a temperature control device, and a number of thermal conducting elements. A thermal conducting element thermally couples at least one individual cell to the temperature control device. The thermal conducting element is formed from two halves enclosing a cavity, with at least one of the halves forming a full-surface spring element. The surface of this spring element, spaced apart from the other half, corresponds to at least one surface of a flat side of an electrode foil arrangement, and a spring force generated by the spring element acts essentially perpendicular to the flat side of the electrode foil arrangement.

[0011] From DE 11 2011 103 339 T5, a battery unit is known comprising a first battery module, having several battery cell containers, each holding at least one battery cell, and a second battery module, having several battery cell containers, each holding at least one battery cell, wherein the first battery module and the second battery module are spaced apart. The battery unit further comprises a heat exchanger arranged between the first battery module and the second battery module.The heat exchanger is in contact with the first battery module at a first side and with the second battery module at a second side, wherein the heat exchanger defines at least one internal fluid flow passage for transferring a heat exchanger fluid, and the first and second sides of the heat exchanger are elastically compressible to adapt to changes in the distance between the first and second battery modules across multiple battery cell containers.

[0012] Furthermore, DE 10 2013 200 774 A1 discloses a temperature control device for a battery, which is arranged via a contact surface below the battery base. This contact surface is flexibly designed and is permeated by a fluid. Expansion occurs via the corresponding internal pressure of the fluid.

[0013] The invention is based on the objective of providing a particularly suitable cooling device for a motor vehicle battery. In particular, the cooling device should require the least possible installation effort.

[0014] The problem is solved according to the invention with the features of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

[0015] The cooling device according to the invention is suitable and configured for temperature control of a motor vehicle battery. For this purpose, the cooling device comprises a cooling channel arranged between a surface of the battery (accumulator, cell module) to be cooled and a stationary counter-support (fixed bearing, abutment). The surface of the battery to be cooled (cooling surface) and the counter-support are spaced apart from each other along a z-direction, with the cooling channel arranged in the gap formed thereby. The cooling channel has a bottom surface oriented towards the counter-support and a top surface oriented, in particular, towards the cooling surface of the battery.

[0016] Furthermore, the cooling channel is expandable in the z-direction, so that in its expanded state, its base rests against the counter bearing on one side and its top surface rests against the battery's cooling surface on the other. Due to the expansion of the cooling channel itself, no additional components or manufacturing steps are required to compensate for or bridge manufacturing tolerances in the gap area. This reduces the assembly effort of the cooling device, which has a positive impact on manufacturing costs.

[0017] The battery is designed, for example, as a lithium-based accumulator cell, with several such batteries being connectable to form a common battery system. In a typical installation, the resulting battery system, or the individual batteries, are integrated into a (battery) housing of the vehicle. The counter bearing is formed, for example, by a housing wall. The vehicle is, in particular, an electric or hybrid vehicle, with the power of the battery(ies) being used to supply an electric motor drive.

[0018] The distance between the bottom surface and the top surface essentially defines the height of the cooling channel. The channel's longitudinal direction is oriented along the x-direction, while the channel's transverse direction, i.e., its width, is oriented along the y-direction. This means that the battery's cooling surface and the support, or the top surface and the bottom surface, are oriented parallel to the xy-plane. The bottom and top surfaces of the cooling channel are preferably flat, so that in the expanded state, they lie homogeneously and flush against the cooling surface or the support. The cooling channel thus has an essentially rectangular cross-section along its longitudinal and x-directions.

[0019] Expansion of the cooling channel, in this context, refers specifically to a relative movement of the top surface to the bottom surface; that is, a movement of the top surface and / or the bottom surface along the z-direction. In other words, the cooling channel expands, at least partially, in space. This means that in the expanded state, the cooling channel has, for example, an increased cross-sectional area, or at least an increased channel height along the z-direction. In other words, the cooling channel has a greater height in the expanded state than in the unexpanded state.

[0020] The counter bearing and the battery's cooling surface are essentially fixed, so the expansion of the cooling channel essentially clamps it in place within the gap. In other words, a contact force is exerted on the cover surface in the direction of the cooling surface, ensuring a reliable and secure system. This guarantees effective heat transfer between the battery and the cooling channel at all times during operation.

[0021] The cooling channel preferably expands such that the gap area – at least along the z-direction – is essentially completely filled by the cooling channel. This means that the channel height in the expanded state is essentially identical to the gap dimension of the gap area.

[0022] In a practical embodiment, the cooling channel is permeated by a cooling medium during operation. The cooling channel is designed to expand under the pressure of the cooling medium. Preferably, the cooling channel expands solely due to the (operating) pressure of the cooling medium (coolant, cooling fluid), so that the contact force between the battery's cooling surface and the cooling channel's cover surface is generated without additional components or energy sources. In other words, this design provides a simple and advantageous functional integration of the cooling channel, as it expands essentially automatically during operation. This ensures particularly low assembly effort.

[0023] For this purpose, the cooling device is, for example, coupled to a vehicle's cooling circuit, with the cooling device and the cooling circuit preferably forming a closed system for conveying the cooling medium. The cooling circuit is, for example, part of an air conditioning system for temperature control of a vehicle's interior. The cooling medium has, for example, an operating pressure of approximately 1 to 6 bar. Preferably, water with an operating pressure of 1 to 3 bar is used as the cooling medium. Alternatively, the use and conveyance of a refrigerant with an operating pressure between 1 and 30 bar is also conceivable. In this case, the expansion or the contact pressure or force for the cover surface to adhere to the cooling surface is caused solely by the operating pressure of the cooling medium.

[0024] This operating pressure is directed as internal pressure on the inner walls of the cooling channel, meaning that the cooling medium pushes the bottom and / or top surfaces outwards. In other words, the operating pressure acts radially on the inner walls along the longitudinal direction (x-direction) of the channel. This ensures a homogeneous distribution of the forces acting on the top and bottom surfaces. Consequently, the contact forces acting on the cooling surface and the counter-support are approximately equal. This reduces the requirements for local stiffness and stability of the cooling surface and the counter-support, which advantageously translates into a reduction in their respective weights.

[0025] In a suitable design, at least a portion of the cooling channel consists of an expandable or foldable material. This allows for the relative movement of the top surface to the bottom surface during expansion.

[0026] In one possible design, for example, the side walls of the cooling channel—that is, the side surfaces oriented in the z-direction between the top and bottom surfaces—are made of a stretchable material. A stretchable material in this context is understood to be, in particular, a flexible material that can be deformed and / or bent. This causes the cooling channel to expand or swell, at least partially, during expansion, especially due to the pressure of the cooling medium, at least in the area of ​​the side surfaces, thereby moving the top and bottom surfaces away from each other.

[0027] In a conceivable alternative design, the side surfaces are made of a foldable material. This means that the side surfaces are essentially made of an elastic material and, for example, have a bellows-like or accordion-like deformation contour. During operation, the deformation contour is unfolded during expansion, thus increasing the channel height in the z-direction.

[0028] In one embodiment according to the invention, the cooling channel is formed in two parts, comprising a first profile part and a second profile part. The cooling channel advantageously forms a circumferentially closed guide for the cooling medium, such that, in a suitable embodiment, the two profile parts overlap in the z-direction. This overlap area is preferably designed to be sealed with respect to the cooling medium. For this purpose, it is conceivable, for example, that the profile parts are joined together in the overlap area by a material bond, for example by gluing or welding. Separate sealing elements, such as a sealing rubber or a sealing lip, which can be attached in the overlap area, are also conceivable.

[0029] An additional aspect of the invention provides that the two profile parts are made of different materials. The first profile part preferably comprises the top surface, while the second profile part suitably comprises the bottom surface. This allows for a functional separation of the top and bottom surfaces, thereby creating additional freedom in the design and manufacture of the cooling channel.

[0030] The first profile section, comprising the cover surface, is designed to ensure a homogeneous and uniform contact with the battery's cooling surface. This means that heat transfer between the cooling medium and the battery occurs primarily via the cover surface. For particularly effective heat transfer, the first profile section is therefore made of a material that, on the one hand, exhibits the highest possible thermal conductivity. On the other hand, the desired material possesses the highest possible stability or stiffness so that it does not bulge or bend during the expansion of the cooling channel. In one embodiment according to the invention, the first profile section is therefore made of a metal. In particular, aluminum, an aluminum material, or an aluminum alloy is used as the metal, so that the first profile section is essentially designed as an aluminum profile or an aluminum rail.

[0031] In a further development according to the invention, the second profile part, which has the base surface, is made of a plastic, in particular an elastomeric material. The plastic is preferably designed to be stretchable or foldable, so that the expansion of the cooling channel is essentially achieved by means of at least partial expansion of the second profile part.

[0032] Advantageously, a flexible and elastic plastic, such as a rubber material or a thermoplastic elastomer (TPE), like nitrile rubber (nitrile butadiene rubber, NBR), is used. It is essential that the plastic exhibits sufficient elasticity for expansion within the temperature range to be controlled in the battery system, such as -10°C to +50°C, so that a flush contact between the cover surface and the cooling surface is always ensured. This makes the second plastic profile section sufficiently flexible to transfer the resulting contact force onto the cover surface via the internal pressure generated by the cooling medium during operation.

[0033] In a preferred embodiment, the two profile sections of the cooling channel are designed as U-profiles. This means that the profile sections have a substantially U-shaped cross-section in the yz plane, with the horizontal legs of the U forming the top and bottom surfaces, respectively. The first profile section, which forms the top surface, overlaps the second profile section in such a way that the outer surfaces of the second profile section abut the inner surfaces of the first profile section. In other words, the U-shaped profile sections are essentially nested within one another, with the vertical legs of the first profile section at least partially overlapping the vertical legs of the second profile section from the outside in the z-direction.

[0034] This means that the U-profile of the first profile section at least partially surrounds the U-profile of the second profile section, so that the second profile section is at least partially embedded in the vertical U-legs of the first profile section. Thus, the horizontal U-leg of the first profile section overlaps the opening of the second profile section, forming a substantially closed channel for the cooling medium.

[0035] The vertical U-shaped legs of the U-profiles are suitably sealed or connected to each other in the overlap area to prevent any cooling medium from escaping during operation. For the construction of the cooling channel, it is conceivable, for example, that the metallic first profile part is bonded to the plastic second profile part or at least partially overmolded by it.

[0036] In one conceivable installation scenario, the counter bearing is formed by the base surface of another, particularly parallel, cooling channel, which has a further cover surface that rests against another surface of a further battery to be cooled. This design is particularly advantageous for a stacked arrangement or a cell cluster of several adjacent batteries to form a common battery system. This results in particularly efficient, uniform, and component-reduced cooling of adjacent batteries.

[0037] The mutual support of the cooling channels at their respective base surfaces eliminates the need for additional partitions between the individual batteries. This allows for a particularly simple and cost-effective battery housing, which is significantly lighter, as no partitions are required to act as counter-supports between the individual batteries. In a potential application, this reduced weight translates into an improved range for the electric vehicle.

[0038] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 In schematic representation a side view of a motor vehicle battery with a cooling device with a cooling channel arranged between the battery and a battery housing, Fig. 2 the cooling channel in a cross-sectional view, Fig. 3. the cooling channel in a perspective view, and Fig. Figure 4 shows a schematic side view of two adjacent batteries with two cooling channels arranged between them and supported against each other.

[0039] Corresponding parts and sizes are always marked with the same reference symbols in all figures.

[0040] In the Fig. Figure 1 shows a cooling device 2 for a battery 4 of a motor vehicle (not shown in detail), in particular an electric or hybrid vehicle. The battery 4 is, for example, designed as a lithium-based accumulator and is arranged as part of a battery system 6 comprising several such batteries 4 in a (battery) housing 8 of the motor vehicle. In the Fig. Figure 1 merely shows a fixed housing wall 10 of the housing 8.

[0041] The cooling device 2 has a circumferentially closed cooling channel 12 for guiding a cooling medium. For this purpose, the cooling channel 12 has a connection part 14 at one end face 12a, by means of which the cooling channel 12 is connected to a cooling circuit of the motor vehicle (not shown in detail).

[0042] For the purpose of temperature control of the battery 4, the cooling channel 12 is in thermal contact with a surface 16 of the battery 4 to be cooled or cooled. In the exemplary embodiment of the Fig. In the illustrated embodiment, the cooling channel 12 is arranged in a gap 18 formed between the surface 16 and the housing wall 10. In this installation, the surface 16 and the housing wall 10 are spaced apart from each other along a z-direction. The longitudinal direction of the channel is oriented along the x-direction, so that the surface 16 and the counter bearing 10 formed by the housing wall are aligned parallel to the xy-plane.

[0043] As in the Fig. 2 and Fig. As can be seen in Figure 3, the hollow-profile cooling channel 12 is composed of two profile sections (U-profile, profile rail) 20, 22, each with an approximately U-shaped cross-section. The openings of the U-legs face each other, forming a closed channel chamber (hollow chamber) 24 for the cooling medium. The horizontal U-leg 20a of the battery-side profile section 20 forms a top surface of the cooling channel 12. The horizontal U-leg 22a of the housing-side profile section 22, arranged opposite this, forms a bottom surface of the cooling channel 12. The top surface 20a and the bottom surface 22a are parallel to each other.

[0044] In its assembled state, profile part 20 covers profile part 22 such that the outer surfaces of the vertical U-shaped legs 22b of profile part 22 abut the inner surfaces of the vertical U-shaped legs 20b of profile part 20. In other words, profile part 22 is essentially nested within profile part 20, with the vertical U-shaped legs 20b at least partially overlapping the vertical U-shaped legs 22b along their outer sides in the z-direction. Profile parts 20 and 22 are sealed together in this overlap area 26.

[0045] In this embodiment, profile part 20 is made of aluminum. This ensures high thermal conductivity between the cooling medium guided within the cooling channel 12 and the cooling surface 16 of the battery. Profile part 22 is made of a flexible and elastic plastic material, in particular an elastomeric rubber material.

[0046] During operation, the cooling medium flows through the cooling channel 12. The cooling medium is at an operating pressure, which acts as internal pressure against the inner walls of the approximately rectangular channel chamber 24. The pressure of the cooling medium, or the elasticity of the profile section 22, is sufficiently high that at least partial elastic deformation of the profile section 22 occurs outwards. Since the U-shaped legs 22b are firmly enclosed by the U-shaped legs 20b of the essentially rigid profile section 20, the profile section 22 expands in the direction of the cooling surface 16.

[0047] This converts the internal pressure generated by the cooling medium into a contact pressure or force, which presses the base surface 22a against the counter bearing 10 and the cover surface 20a against the cooling surface 16. In other words, the cooling channel 12 expands along the z-direction, thus compensating for or bridging manufacturing tolerances in the gap area 18. This ensures that the thermally conductive cover surface 20a of the cooling channel 12 is in particularly effective thermal contact with the cooling surface 16 of the battery 4.

[0048] The one in Fig. The embodiment shown in Figure 4 depicts the battery system 6 with two adjacent batteries 4. In this embodiment, the cooling device 2 has two cooling channels 12 adjacent or stacked in the z-direction. The cooling channels 12 are flush against each other along their longitudinal direction (x-direction) at their respective bottom surfaces 22a. In other words, the bottom surface 22a of the first cooling channel 12 forms a counter-support for the bottom surface 22a of the second cooling channel 12, and vice versa. This means that the cooling channels 12 are supported against each other during expansion.

[0049] In the illustrated embodiment of the Fig. In section 4, the cooling channels 12 are arranged parallel to each other, with the flow direction of the cooling medium guided through the connection parts 14 being in the same direction. However, a design with an opposite flow direction is also conceivable, for example.

[0050] With suitable dimensions, the gap area 18, or the distance between two adjacent batteries 4, has a gap dimension of approximately 20 to 25 mm. The gap dimension here refers specifically to the clear width or distance in the z-direction between the cooling surface 16 and the housing wall 10, or between two adjacent cooling surfaces 16. The manufacturing tolerances occurring, or the differences in the gap dimension within the battery system 6, are, for example, between 0.2 and 1 mm.

[0051] The cooling channel 12 extends essentially over the entire length of the associated battery 4 and has, for example, a channel length of approximately 350 mm in the x-direction and a channel width of approximately 150 mm in the y-direction.

[0052] The invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the embodiments can also be combined with one another in other ways without departing from the subject matter of the invention.

[0053] For example, it is conceivable to use a refrigerant instead of a cooling medium for the cooling device 2. The use of a refrigerant is particularly advantageous in applications where the ambient temperature of the battery system 6 is higher than the specified or desired (operating) temperature at which the batteries 4 are to be maintained.

[0054] Typically, refrigerants in motor vehicles have a significantly higher operating pressure (up to 80 bar) compared to the cooling medium.

[0055] For this purpose, it is conceivable, for example, to attach separate sealing elements in the overlap area 26 to ensure sufficient tightness of the channel chamber 24. Additionally or alternatively, it is possible to at least partially overmold the metallic profile part 20 with the plastic-like profile part 22 to produce the cooling channel 12.

Claims

[1] Cooling device (2) for a battery (4) of a motor vehicle with a cooling channel (12) arranged between a surface (16) of the battery (4) to be cooled and a counter bearing (10, 22a), - wherein the surface to be cooled (16) and the counter bearing (10, 22a) are spaced apart from each other in a z-direction and the cooling channel (12) has a bottom surface (22a) oriented towards the counter bearing (10, 22a) and a top surface (20a) oriented towards the battery (4), - wherein the cooling channel (12) is formed in two parts with a first profile part (20) and a second profile part (22), - wherein the first profile part (20) having the cover surface (20a) is made of a metal, - wherein the second profile part (22) having the base surface (22a) is made of a plastic, and - wherein the cooling channel (12) can be expanded by at least a partial expansion of the second profile part (22) in the z-direction, so that the cooling channel (12) in the expanded state is in contact with the counter bearing (10, 22a) with its bottom surface (22a) and with the top surface (20a) with the surface (16) to be cooled. [2] Cooling device (2) according to claim 1, characterized by , that the cooling channel (12) is through which a cooling medium flows during operation, wherein the cooling channel (12) is designed such that it is expanded by the pressure of the cooling medium. [3] Cooling device (2) according to claim 1 or 2, characterized by , that at least the second profile part (22) of the cooling channel (12) consists of a stretchable or foldable plastic material. [4] Cooling device (2) according to any one of claims 1 to 3, characterized by , that the two profile parts (20, 22) overlap in the z-direction. [5] Cooling device (2) according to any one of claims 1 to 4, characterized by, that the two profile parts (20, 22) are designed as U-profiles, wherein the first profile part (20) having the cover surface (20a) covers the second profile part (22) in such a way that outer surfaces of the second profile part (22) are in contact with the inner surfaces of the first profile part (20). [6] Cooling device (2) according to any one of claims 1 to 5, characterized by , that the counter bearing (22a) is formed by a bottom surface (22a) of a further cooling channel (12) which has a further cover surface (20a) which is adjacent to a further surface (16) to be cooled of a further battery (4).

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