Heat exchanger

Abstract

To prevent a decrease in heat exchange efficiency in heat exchangers that are stacked alternately with battery cells of an in-vehicle battery to exchange heat.SOLUTION: A heat exchanger for heat exchange, which is stacked with battery cells of an on-board battery, includes a metal shell member that forms a flow path for a heat exchange fluid, and an insulating film coated on the outer or inner surface of the shell member. An oxide film formed on the surface of the shell member prevents the insulating sheet attached to the surface of the shell member from shifting, which would reduce heat exchange efficiency.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a heat exchanger. [Background technology]

[0002] As described in Patent Document 1, a stacked cooling tube is known in which the tubes are alternately stacked with the heating element. This cooling tube cools the heating element by circulating a refrigerant in an internal space surrounded by two outer shell plates. For this purpose, the outer surfaces of the outer shell plates are connected to the outer wall of the heating element via a bonding material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-162922 Summary of the Invention [Problem to be solved by the invention]

[0004] When the object to be heat exchanged is an on-board battery mounted on a vehicle, insulation is required between the battery cells and the outer shell members, such as the outer shell plate, or between the battery cells and a fluid, such as a refrigerant. To achieve this insulation between the battery cells and the outer shell members or the fluid, one possible approach is to attach an insulating sheet to the outer or inner surface of the outer shell members via an adhesive.

[0005] However, if the outer shell member is made of a highly corrosion-resistant metal such as aluminum or stainless steel, an oxide film will form on the metal surface, making it difficult for the outer shell member and the adhesive to chemically bond. Therefore, in this case, the insulating sheet may shift due to expansion and contraction of the battery cell and outer shell member, allowing air to enter between the outer shell member and the insulating sheet, resulting in a problem of reduced heat exchange efficiency by the heat exchanger.

[0006] An object of one aspect of the present disclosure is to suppress a decrease in heat exchange efficiency in a heat exchanger that exchanges heat by being alternately stacked with battery cells of an in-vehicle battery. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a heat exchanger for exchanging heat with battery cells of an on-board battery, the heat exchanger including a metal shell member that forms a flow path for a heat exchange fluid, and an insulating film that is applied to an outer surface or an inner surface of the shell member.

[0008] In this way, according to the heat exchanger of the present disclosure, an insulating film is provided on the outer or inner surface of the shell member, thereby providing insulation between the battery cells and the shell member, or between the battery cells and the fluid. Furthermore, because the insulating film is provided on the outer or inner surface of the shell member by painting, it is possible to prevent air and the like from entering the bonded portion between the shell member and the insulating material, as would be the case if an insulating material such as an insulating sheet were provided on the surface.

[0009] Therefore, the heat exchanger of the present disclosure can prevent a decrease in heat exchange efficiency due to an oxide film formed on the surface of the outer shell member. Furthermore, since the insulating film does not need to be attached via an adhesive, as is the case with insulating sheets, manufacturing costs can also be reduced.

[0010] Here, the outer shell member may be made of stainless steel. Stainless steel forms an oxide film called a passive film on its surface. However, in the heat exchanger of the present disclosure, an insulating film is applied to the surface of the outer shell member by painting, which prevents air and other particles from penetrating between the oxide film on the stainless steel surface of the outer shell member and the insulating film. Therefore, even if the outer shell member is made of stainless steel, the passive film on its surface can prevent a decrease in heat exchange efficiency.

[0011] The insulating film may also be a cationic electrodeposition coating film. Cationic electrodeposition coating films have excellent corrosion resistance and can be uniformly formed on the surface of the outer shell member. Therefore, by using a cationic electrodeposition coating film as the insulating film, the insulating film can be more firmly laminated on the surface of the outer shell member, preventing air and other particles from entering between the insulating film and the outer shell member. Therefore, by doing so, a decrease in the heat exchange efficiency of the heat exchanger can be more effectively prevented.

[0012] The insulating film may be provided on the outer surface of the outer shell member, and the heat exchanger may be arranged to exchange heat with the battery via a thermally conductive sheet. In this way, when a thermally conductive sheet is provided on the outer surface of the outer shell member, the thermally conductive sheet and the outer shell member can be closely attached via the coating film provided on the outer surface of the outer shell member.

[0013] This prevents a decrease in thermal conduction between the battery and the outer shell member, as occurs when an insulating sheet is provided on the outer surface of the outer shell member, thereby increasing the heat exchange efficiency of the heat exchanger. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram illustrating the overall configuration of a heat exchanger according to a first embodiment. [Figure 2] FIG. 2 is a perspective view illustrating a configuration of a heat exchange unit according to the embodiment. [Figure 3] 3 is a cross-sectional view of the heat exchange unit shown in FIG. 2 taken along line AA. [Figure 4] 4 is an enlarged cross-sectional view of a stacked portion B of the heat exchange unit and the battery cell shown in FIG. 3. FIG. [Figure 5] 10 is an enlarged cross-sectional view showing a stacked portion B of a heat exchange unit and a battery cell according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [Embodiment] The heat exchanger 2 of this embodiment is a stacked heat exchanger that is mounted on an electric vehicle and suppresses temperature rise of the battery by exchanging heat with the battery that supplies power to the motor and other devices that serve as the power source of the vehicle.

[0016] An electric vehicle is a vehicle that runs by driving a power source such as a motor using electrical energy stored in a battery, and includes electric vehicles, plug-in hybrid vehicles, and hybrid vehicles.

[0017] 1, the heat exchanger 2 includes a plurality of heat exchange units 10 arranged alternately with a plurality of battery cells 4 that constitute an on-board battery. The plurality of battery cells 4 are cells that constitute chargeable and dischargeable secondary batteries, and are connected to each other in series or in parallel. Therefore, the battery cells 4 are arranged at predetermined intervals in the X-axis direction along the surface that contacts the heat exchange unit 10, and in the Y-axis direction that is perpendicular to the X-axis.

[0018] In contrast, the heat exchange unit 10 has a length corresponding to the overall length of the multiple battery cells 4 arranged in the X-axis direction, and is arranged between and outside the multiple battery cells 4 arranged in the Y-axis direction so as to be in contact with each battery cell 4.

[0019] 2, the contact surface of the heat exchange unit 10 with the battery cell 4 has a width in the Z-axis direction, which is orthogonal to the X-axis and Y-axis, substantially the same as the width of the battery cell 4 in the Z-axis direction, and is an elongated shape that is long in the X-axis direction. Also, the thickness of the heat exchange unit 10 in the Y-axis direction is shorter than the width in the Z-axis direction and corresponds to the spacing of the battery cells 4 in the Y-axis direction. Therefore, the heat exchange unit 10 has a flat shape.

[0020] As described above, the heat exchange units 10 constituting the heat exchanger 2 are arranged between and outside the battery cells 4 arranged in the Y-axis direction, thereby forming a stack with the battery cells 4. Then, as shown in FIG. 1 , the stack is restrained by a restraining member 40 for each assembled battery 8 made up of the battery cells 4 arranged in the Y-axis direction.

[0021] The restraining member 40 is used to apply a pressing force in the stacking direction to each battery pack 8 to hold the battery cells 4 between the heat exchange units 10, and includes a pair of end plates 42, 44 and four restraining bands 46 that connect the end plates 42, 44.

[0022] The pair of end plates 42, 44 are arranged outside the heat exchange units 10 located at both ends of the battery pack 8 in the stacking direction (Y-axis direction). Each end plate 42, 44 is a plate-like member having a plate surface approximately the same size as the opposing surfaces of the battery cells 4 arranged opposite each other across the heat exchange unit 10, and is made of a metal plate whose plate surface will not deform when restrained. The end plates 42, 44 may also be made of synthetic resin.

[0023] The restraint bands 46 are provided at two locations in the X-axis direction of the battery pack 8, with a predetermined gap between them. The restraint bands 46 are also arranged on both sides in the short direction (Z-axis direction) of the heat exchange unit 10. Therefore, the restraint bands 46 are arranged at four locations around the battery pack 8.

[0024] The restraint bands 46 are elongated in the stacking direction of the battery pack 8, and both ends are bent toward the end plates 42, 44. The bent portions are fixed to the outer surfaces of the end plates 42, 44 on the side opposite the battery pack 8.

[0025] As a result, the battery pack 8 is sandwiched between the end plates 42, 44 on both sides in the stacking direction, and a predetermined pressing force is applied to the heat exchange unit 10 that constitutes the battery pack 8, making surface contact with the battery cells 4 and enabling efficient heat exchange.

[0026] Next, as shown in FIG. 2, the heat exchange unit 10 includes a main body 12 that is stacked on the battery cell 4 to perform heat exchange, and a first connecting pipe 14 and a second connecting pipe 16 that protrude from the front and back sides of the main body 12 that are stacked on the battery cell 4 at both ends in the longitudinal direction (X-axis direction) of the main body 12, respectively.

[0027] 3, the main body 12 includes a pair of outer shell members 20 on the front and back sides, and a flow path 22 for flowing a heat exchange fluid F between the pair of outer shell members 20. That is, the outer shell members 20 are formed by press-forming a metal plate made of stainless steel, so that the outer surface that contacts the battery cell 4 bulges outward and the inner surface is recessed. The main body 12 is formed by placing the inner surfaces of the pair of outer shell members 20 opposite each other and joining the entire outer periphery by welding or the like, thereby forming a space inside that serves as the flow path 22 for the fluid F.

[0028] The first connecting pipe 14 and the second connecting pipe 16 are cylindrical pipes made of metal, and are used to supply or discharge the fluid F to or from the flow path 22 inside the heat exchange unit 10. The first connecting pipe 14 and the second connecting pipe 16 are configured to be able to fit together.

[0029] Therefore, by fitting the first connecting pipe 14 and the second connecting pipe 16 on both ends of adjacent heat exchange units 10 together, a pair of connecting pipes 30 (see FIG. 1) can be formed that connect the flow paths 22 of each heat exchange unit 10. Therefore, as shown in FIG. 1, by supplying fluid F to one of the pair of connecting pipes 30 and discharging fluid F from the other connecting pipe 30, the fluid F can be made to flow through the flow paths 22 of each heat exchange unit 10.

[0030] Specifically, for example, the openings of the first connecting pipe 14 and the second connecting pipe 16 arranged on one end side in the stacking direction of each heat exchange unit 10 (for example, the upper side as shown in FIG. 1) are closed. Then, of the first connecting pipe 14 and the second connecting pipe 16 arranged on the other end side in the stacking direction of each heat exchange unit 10 (for example, the lower side as shown in FIG. 1), the fluid F is supplied from the opening of the first connecting pipe 14 and discharged from the opening of the second connecting pipe 16. As a result, the fluid F for heat exchange flows through the flow path 22 of each heat exchange unit 10, and heat exchange between each heat exchange unit 10 and the battery cells 4 stacked in each heat exchange unit 10 is promoted.

[0031] Next, the heat exchange fluid F is a substance for cooling or heating the battery cells 4 so that the temperature of the on-board battery is within a predetermined temperature range, and is composed of a liquid or gas. Therefore, by flowing a liquid or gas serving as a refrigerant through the flow path 22 of the heat exchange unit 10 via the pair of connecting pipes 30, the heat exchanger 2 can function as a cooler. Also, by flowing a liquid or gas for heating through the flow path 22 of the heat exchange unit 10 via the pair of connecting pipes 30, the heat exchanger 2 can function as a heater.

[0032] Incidentally, because the outer shell member 20 is made of stainless steel, the outer surface that comes into contact with the battery cells 4 needs to be insulated from the battery cells 4. If an insulating sheet is provided on the surface of the outer shell member 20 for this insulation, air will get in between the outer shell member 20 and the insulating sheet due to misalignment of the insulating sheet, reducing the heat exchange efficiency of the heat exchange unit 10 and, ultimately, the heat exchanger 2.

[0033] The reason why the insulating sheet shifts is that, as mentioned above, an oxide film 24 (see Figure 4) called a passive film is formed on the surface of the outer shell member 20, making it impossible to firmly fix the insulating sheet to the outer surface of the outer shell member 20 using an adhesive or the like.

[0034] Therefore, in this embodiment, as shown in FIG. 4, an insulating film 26 is formed on the outer surface of the outer shell member 20 by painting. In this embodiment, a cationic electrodeposition coating film is used for this insulating film 26. The cationic electrodeposition coating film can be formed on the outer surface of the outer shell member 20, which is the object to be coated, by immersing the outer surface of the outer shell member 20 in a low-concentration, water-soluble electrodeposition paint, and then passing a direct current through the electrodeposition paint as the anode and the outer shell member 20 as the cathode. This coating method is well known, so a detailed description will be omitted here.

[0035] In this embodiment, a thermally conductive sheet 28 is provided as an adhesive layer between the outer shell member 20 of the heat exchange unit 10 on which the insulating film 26 is formed and the battery cell 4.

[0036] The cationic electrodeposition coating film has excellent corrosion resistance and can be firmly formed on the surface of the outer shell member 20, so by using it as the insulating film 26 on the outer surface of the outer shell member 20, it is possible to prevent air and the like from entering between the outer shell member 20 and the battery cell 4. Furthermore, since the cationic electrodeposition coating film can uniformly form the insulating film 26 on the surface of the outer shell member 20, it is possible to adhere the insulating film 26 and the thermally conductive sheet 28 to each other.

[0037] Therefore, according to the heat exchanger 2 of this embodiment, heat exchange between the heat exchange unit 10 and the battery cell 4 can be carried out extremely efficiently, and the heat exchange performance of the heat exchanger 2 can be improved.

[0038] Furthermore, according to the heat exchanger 2 of this embodiment, there is no need to attach the heat conductive sheet 28 to the surface of the outer shell member 20, which simplifies the manufacturing process of the heat exchange unit 10 and reduces manufacturing costs.

[0039] [Second embodiment] In the above embodiment, the insulating film 26 is provided on the outer surface of the shell member 20 of the heat exchange unit 10 to insulate the battery cells 4 from the heat exchange unit 10. However, if the battery cells 4 have a bipolar structure without a housing, the shell member 20 of the heat exchange unit 10 stacked on the battery cells 4 may be used as an electrode connecting the battery cells 4 together.

[0040] Therefore, in such a case, as illustrated in Figure 5, an insulating film 26 made of a cationic electrodeposition coating film may be provided on the entire inner surface of the outer shell member 20, which forms the internal space that becomes the flow path 22 of the heat exchange unit 10.

[0041] In this way, the insulating film 26 insulates the outer shell member 20 of the heat exchange unit 10 from the fluid F flowing through the flow path 22, thereby preventing current from flowing from the battery cell 4 to the outside of the heat exchange unit 10 via the fluid F. Also in this case, the insulating film 26 can increase the heat exchange efficiency between the fluid F flowing through the flow path 22 and the battery cell 4.

[0042] Therefore, according to this embodiment, the oxide film (not shown) formed on the inner surface of the outer shell member 20 can prevent the insulating sheet attached to the inner surface of the outer shell member 20 from shifting, which would result in a decrease in the heat exchange efficiency of the heat exchange unit 10.

[0043] [Other embodiments] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0044] For example, in the above embodiment, the insulating film 26 provided on the outer surface or inner surface of the shell member 20 of the heat exchange unit 10 is described as a cationic electrodeposition coating film. However, the insulating film 26 may be any coating film having insulating properties, and does not necessarily have to be a cationic electrodeposition coating film.

[0045] Furthermore, in the above embodiment, the outer shell member 20 of the heat exchange unit 10 is described as being made of stainless steel, but the outer shell member 20 may be made of a metal other than stainless steel, such as aluminum.

[0046] Furthermore, in the first embodiment, the heat-conductive sheet 28 is provided as an adhesive layer between the outer shell member 20 of the heat exchange unit 10 and the battery cell 4, but the heat-conductive sheet 28 does not necessarily have to be provided.

[0047] In other words, the thermally conductive sheet 28 serving as an adhesive layer is not necessary if the outer shell member 20 of the heat exchange unit 10 and the battery cell 4 can be closely attached via the insulating film 26. Also, instead of the thermally conductive sheet 28, an adhesive or an elastic member may be used as the adhesive layer.

[0048] In addition, in the above embodiment, the multiple heat exchange units 10 are described as having both longitudinal ends connected by a common connecting pipe 30, and within the flow path 22 of each heat exchange unit 10, the heat exchange fluid F flows in the same direction from one connecting pipe 30 to the other connecting pipe 30.

[0049] However, the multiple heat exchange units 10 may be configured, for example, such that both longitudinal ends of the multiple heat exchange units 10 are alternately connected by connecting pipes 30, so that fluid F flows in opposite directions within the flow paths 22 of adjacent heat exchange units 10.

[0050] Furthermore, multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Furthermore, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0051] In addition to the heat exchanger described above, the present disclosure can be realized in various forms, such as a system including the heat exchanger as a component, and a method for manufacturing a heat exchanger. [Technical idea disclosed in this specification] [Item 1] A heat exchanger that is stacked with battery cells of an in-vehicle battery and performs heat exchange, a metal shell member that forms a flow path for a heat exchange fluid; an insulating film coated on an outer surface or an inner surface of the outer shell member; A heat exchanger comprising:

[0052] [Item 2] Item 1, the heat exchanger according to item 1, A heat exchanger, wherein the outer shell member is made of stainless steel.

[0053] [Item 3] The heat exchanger according to item 1 or 2, The heat exchanger, wherein the insulating film is a cationic electrodeposition coating film.

[0054] [Item 4] The heat exchanger according to any one of items 1 to 3, the insulating film is provided on the outer surface of the outer shell member, The heat exchanger is arranged to exchange heat with the battery cell via a thermally conductive sheet. [Explanation of symbols]

[0055] 2...heat exchanger, 4...battery cell, 10...heat exchange unit, 20...outer shell member, 24...oxide film, 26...insulating film, 28...thermal conduction sheet.

Claims

1. A heat exchanger that is stacked with battery cells of an in-vehicle battery and performs heat exchange, a metal shell member that forms a flow path for a heat exchange fluid; an insulating film coated on an outer surface or an inner surface of the outer shell member; A heat exchanger comprising:

2. 2. The heat exchanger of claim 1, A heat exchanger, wherein the outer shell member is made of stainless steel.

3. The heat exchanger according to claim 1 or 2, The heat exchanger, wherein the insulating film is a cationic electrodeposition coating film.

4. The heat exchanger according to claim 1 or 2, the insulating film is provided on the outer surface of the outer shell member, The heat exchanger is arranged to exchange heat with the battery cell via a thermally conductive sheet.

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