Cooling heat exchanger and method for manufacturing cooling heat exchanger

Abstract

Provided is a cooling heat exchanger of a novel structure with which it is possible to achieve high heat exchange efficiency with respect to a cooling object while facilitating work for mounting the cooling object.　A cooling heat exchanger (10) cools a cooling object (36) that flows through a cooling flow path (20) inside of which a cooling heat transfer medium is formed, whereby the cooling object (36) is superposed on a cooling surface (14) provided to a surface. A thermoconductive material layer (26) is disposed on the cooling surface (14). The thermoconductive material layer (26) is a thermoconductive elastic body comprising a molded body of an elastic material in which a thermoconductive filler (30) is mixed. A thermally conductive filler layer (28) is provided between the overlapping surfaces of the cooling surface (14) and the thermoconductive material layer (26), the filler layer (28) being in close contact with each of the overlapping surfaces of the cooling surface (14) and the thermoconductive material layer (26).

Description

Cooling heat exchanger and method of manufacturing the same

[0001] The present invention relates to a cooling heat exchanger used to cool an object to be cooled, such as a battery pack, in an electrically powered vehicle such as an electric automobile.

[0002] In electrically powered vehicles such as electric vehicles and hybrid vehicles, the heat generated by battery packs (e.g., lithium-ion batteries) and electronic devices to be cooled is increasing due to miniaturization and high performance, making cooling performance increasingly important. Conventionally, as disclosed in International Publication No. 2019 / 008000 (Patent Document 1), for example, cooling heat exchangers have been used that have a structure in which cooling channels are formed between overlapping plates. In this cooling heat exchanger, one plate is overlapped with the cooling target, such as a battery pack, and the cooling target is cooled by the one plate being cooled by a refrigerant flowing through the cooling channels.

[0003] International Publication No. 2019 / 008000

[0004] When placing a cooling target on the cooling surface of a cooling heat exchanger, a gap filler may be used to fill the gap between the overlapping surfaces of the cooling surface and the cooling target in order to improve heat exchange efficiency. The gap filler is applied to the cooling surface in a fluid state before placing the cooling target on the cooling surface, and hardens between the cooling surface and the cooling target to form a heat-conductive filler layer that fills the gap between the overlapping surfaces of the cooling surface and the cooling target.

[0005] However, because gap fillers harden over time due to a curing reaction, they cannot be applied to the cooling surface in advance and must be applied immediately before placing the cooling target on the cooling surface, which results in the problem of complicated work involved in mounting the cooling target on the cooling surface of the cooling heat exchanger.

[0006] The problem to be solved by the present invention is to provide a cooling heat exchanger of a novel structure that can easily mount an object to be cooled while achieving high heat exchange efficiency with the object to be cooled.

[0007] Another object of the present invention is to provide a novel method for manufacturing a heat exchanger for cooling.

[0008] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0009] The first aspect is a cooling heat exchanger in which a cooling heat medium flows through a cooling flow path formed inside to cool an object to be cooled that is placed on a cooling surface provided on the surface, and a thermally conductive material layer is arranged on the cooling surface, and the thermally conductive material layer is a thermally conductive elastic body made of a molded body of an elastic material mixed with a thermally conductive filler, and a thermally conductive filler layer is provided between the overlapping surfaces of the cooling surface and the thermally conductive material layer, and is in close contact with each of the overlapping surfaces of the cooling surface and the thermally conductive material layer.

[0010] In a cooling heat exchanger constructed according to this aspect, the surface that is directly attached to the object to be cooled is made of an elastic thermally conductive layer, and the space between the thermally conductive layer and the cooling surface is filled with a filler layer. Therefore, even if the pre-formed filler layer is completely hardened, the elasticity of the thermally conductive layer that forms the surface that is attached to the object to be cooled effectively exhibits adhesion to the object to be cooled and interference with input loads caused by the installation of the object to be cooled.

[0011] In addition, since the space between the overlapping surfaces of the thermally conductive material layer and the cooling surface is filled with a filler layer, it is difficult for gaps to remain between the thermally conductive material layer and the cooling surface, so a sufficiently high thermal conductivity can be achieved and sufficient cooling performance can be obtained for the object to be cooled.

[0012] Furthermore, since the filler layer is formed of a flexible filler that adheres to both the cooling surface and the thermally conductive layer, and the filler hardens over time due to contact with the surrounding air, the hardening rate of the filler layer is reduced because both sides of the filler layer are covered by the cooling surface and the thermally conductive layer, reducing the contact area of ​​the filler layer with air. This allows the flexibility of the filler layer to be maintained for a longer period of time, and the flexibility of the filler layer can be used, for example, to ensure adhesion and cushioning when attached to an object to be cooled.

[0013] In a second aspect, in the cooling heat exchanger described in the first aspect, a hardening adjustment sheet is provided that covers the outer peripheral surface of the packing layer and suppresses the hardening reaction of the packing layer.

[0014] In the cooling heat exchanger constructed according to this embodiment, for example, when the filler hardens over time due to contact with the surrounding air, the hardening of the filler layer can be further delayed by covering both sides of the filler layer with the cooling surface and the heat conductive material layer, and by covering the outer peripheral surface of the filler layer with the hardening adjusting sheet. Therefore, the filler layer can be kept flexible for a longer period of time, and the flexibility of the filler layer can be utilized when attaching it to an object to be cooled.

[0015] A third aspect is a cooling heat exchanger according to the first or second aspect, wherein a large number of the thermally conductive fillers are oriented so as to form a heat transfer path within the thermally conductive material layer.

[0016] In a cooling heat exchanger constructed according to this embodiment, the thermal conductivity of the thermally conductive material layer can be increased in the orientation direction of the thermally conductive filler. Therefore, by aligning the orientation direction of the thermally conductive filler with the overlapping direction of the cooling surface and the cooling object, the heat exchange efficiency between the cooling surface and the cooling object can be increased.

[0017] In a fourth aspect, in the heat exchanger for cooling according to any one of the first to third aspects, the thermally conductive material layer is a foam.

[0018] In a cooling heat exchanger constructed in accordance with this embodiment, the thermally conductive material layer is made of a foam, which makes it easier to achieve softer characteristics against compression. Therefore, when the object to be cooled is attached, the cushioning effect caused by the compressive deformation of the thermally conductive material layer is more effectively exerted, and damage to the object to be cooled and the cooling heat exchanger due to the input force caused by the object to be cooled being pressed against the cooling heat exchanger is more effectively prevented.

[0019] A fifth aspect is a cooling heat exchanger according to any one of the first to fourth aspects, wherein the thermally conductive material layer is thicker and softer than the filler layer.

[0020] In a cooling heat exchanger constructed in accordance with this embodiment, the heat conduction material layer is thicker and softer than the filler layer, so that even when the filler layer has completely hardened and can hardly exert any cushioning effect, the heat conduction material layer still provides cushioning when the object to be cooled is attached and adheres closely to the object to be cooled.

[0021] A sixth aspect is a cooling heat exchanger according to any one of the first to fourth aspects, wherein the filler layer is thicker and softer than the thermally conductive material layer.

[0022] In a cooling heat exchanger constructed in accordance with this embodiment, the filler layer is thicker and softer than the thermally conductive material layer, so that the filler layer provides a cushioning effect when the object to be cooled is attached.

[0023] A seventh aspect is a cooling heat exchanger according to any one of the first to sixth aspects, wherein the surface of the thermally conductive material layer that overlaps with the object to be cooled is a convex surface.

[0024] In a cooling heat exchanger constructed according to this aspect, when an object to be cooled is placed on the thermally conductive layer, the contact area of ​​the thermally conductive layer with the object to be cooled gradually expands outward from the apex of the convex surface, making it difficult for air to remain between the surfaces of the thermally conductive layer and the object to be cooled. This makes it easier to ensure a large effective contact area between the object to be cooled and the cooling heat exchanger, thereby improving the heat exchange efficiency between the object to be cooled and the cooling heat exchanger.

[0025] The eighth aspect is a method for manufacturing a cooling heat exchanger in which a cooling heat medium flows through a cooling flow path formed inside to cool a cooling object placed over a cooling surface provided on the surface, and includes the steps of: (a) molding an elastic material mixed with a thermally conductive filler to prepare a thermally conductive material layer; (b) placing a soft, thermally conductive filler on the cooling surface; and (c) overlaying the thermally conductive material layer on the soft filler placed on the cooling surface, and compressing and hardening the filler between the cooling surface and the thermally conductive material layer to form a filler layer between the overlapping surfaces of the cooling surface and the thermally conductive material layer, and then tightly adhering the filler layer to each of the overlapping surfaces of the cooling surface and the thermally conductive material layer.

[0026] According to the manufacturing method of the cooling heat exchanger of this embodiment, the gap between the overlapping surfaces of the thermally conductive material layer and the cooling surface is filled with the filler layer, thereby achieving excellent thermal conductivity between the cooling surface and the thermally conductive material layer.

[0027] Since both sides of the filler layer are covered by the cooling surface and the thermally conductive material layer, the filler layer is less exposed to the external space. Therefore, for example, when the filler layer is formed using a one-component filler that hardens upon contact with air, the hardening speed of the filler is reduced, and the flexibility of the filler layer can be maintained for a longer period of time.

[0028] According to the present invention, in a cooling heat exchanger, it is possible to easily mount an object to be cooled, and to achieve high heat exchange efficiency between the object to be cooled and the cooling heat exchanger.

[0029] FIG. 1 is a longitudinal cross-sectional view showing a cooling heat exchanger according to a first embodiment of the present invention; FIG. 2 is a longitudinal cross-sectional view showing the cooling heat exchanger of FIG. 1 with a battery pack attached; FIG. 3 is a longitudinal cross-sectional view showing a cooling heat exchanger according to a second embodiment of the present invention;

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0031] 1 shows a cooling heat exchanger 10 according to a first embodiment of the present invention. The cooling heat exchanger 10 has a structure in which a cooling surface coating layer 16 is provided on a cooling surface 14 of a cooling plate body 12. In the following description, in principle, the vertical direction refers to the vertical direction in FIG. 1 , which is the stacking direction of the cooling plate body 12 and the cooling surface coating layer 16, the left-right direction refers to the left-right direction in FIG. 1 , and the front-rear direction refers to the direction perpendicular to the plane of the paper in FIG. 1 .

[0032] The cooling plate body 12 has an overall rectangular plate shape. Bolt insertion holes 18 are formed at both left and right end portions of the cooling plate body 12, respectively, penetrating in the vertical direction. The thickness dimension T1 of the cooling plate body 12 is preferably within a range of 3 to 30 mm, more preferably within a range of 3 to 10 mm. A cooling flow channel 20 is formed inside the cooling plate body 12, through which a cooling heat medium flows. The cooling flow channel 20 is not particularly limited in terms of its path, cross-sectional shape, cross-sectional area, etc., as long as it allows the cooling heat medium (refrigerant) to flow from one end to the other. The cooling flow channel 20 in this embodiment may be, for example, a serpentine shape that folds back at both front-rear end portions, a planar double spiral shape, or a plurality of straight lines extending in parallel.

[0033] The cooling plate body 12 of this embodiment has a structure in which a first plate 22 and a second plate 24 are stacked in the vertical direction. A cooling flow path 20 is formed between the overlapping surfaces of the first plate 22 and the second plate 24. In this embodiment, the first plate 22 is flat, and a groove opening to the upper surface is formed in the second plate 24. The opening of the groove in the second plate 24 is covered by the first plate 22, thereby forming the cooling flow path 20 inside the cooling plate body 12. However, for example, the cooling flow path 20 inside the cooling plate body 12 may be formed by vertically butting a groove opening to the lower surface of the first plate 22 and a groove opening to the upper surface of the second plate 24 against each other.

[0034] The upper first plate 22 is preferably made of a material with high thermal conductivity, such as a metal such as stainless steel or aluminum alloy, or a hard synthetic resin mixed with a thermally conductive filler. The second plate 24 may be made of a metal that has high deformation rigidity and can be easily thinned, or may be made of a lightweight synthetic resin that has excellent shape flexibility.

[0035] A cooling surface 14 is provided on the upper surface of the first plate 22. The shape and size of the cooling surface 14 are not particularly limited and are set, for example, according to the cooling target (battery pack 36) described below. The cooling surface 14 is set above the area where the cooling flow passage 20 is formed, and is close to the cooling flow passage 20. In this embodiment, the cooling surface 14 is set to extend slightly outward beyond the cooling flow passage 20. The bolt insertion holes 18, 18 are formed in positions offset to the left and right of the cooling surface 14.

[0036] The cooling surface covering layer 16 provided on the cooling surface 14 of the first plate 22 is configured to include a heat conductive material layer 26 and a filler material layer 28 .

[0037] The thermally conductive material layer 26 is an elastic body. The thermally conductive material layer 26 is preferably formed from a material with high thermal conductivity. The thermally conductive material layer 26 is preferably a foam body with numerous bubbles 29 formed therein, and more preferably, the bubbles 29 are independent of one another. The thermally conductive material layer 26 is a thermally conductive elastic body in which a thermally conductive filler 30 with high thermal conductivity is mixed into a base material made of an elastic material such as synthetic resin or rubber. The base material of the thermally conductive material layer 26 is preferably a urethane-based, silicone-based, or acrylic-based synthetic resin, and in this embodiment, a soft urethane foam is used. The thermally conductive material layer 26 is preferably a molded product, and in this embodiment, is molded into a substantially rectangular plate shape.

[0038] The thermally conductive filler 30 is formed from a metal or the like and can be formed in various shapes, such as spherical (including oval and oblong spheres), columnar, conical, foil, and fibrous. The thermally conductive filler 30 is sized to allow a large number of particles to be mixed with the base material, and preferably has a maximum outer dimension of 1 μm or more and 5 mm or less. The thermally conductive filler 30 is preferably a magnetic material, and is oriented so that a large number of particles are aligned in the thickness direction to form a heat transfer path by applying a magnetic force in the thickness direction during molding of the thermally conductive material layer 26. Suitable examples of the magnetic thermally conductive filler 30 include iron, stainless steel, nickel, cobalt, manganese oxide, chromium oxide, iron chloride, and alloys thereof. Furthermore, composite particles of graphite and magnetic particles, such as those disclosed as magnetic filler materials in International Publication No. WO 2013 / 042611, can also be used as the thermally conductive filler 30.

[0039] An upper surface 31 of the thermally conductive material layer 26, which is the surface that comes into contact with a battery pack 36 (described later), is a flat surface that extends approximately perpendicular to the up-down direction.

[0040] A protective sheet 32 ​​is superimposed on the upper surface 31 of the thermally conductive material layer 26. The protective sheet 32 ​​prevents foreign matter such as dust from adhering to the upper surface 31 of the thermally conductive material layer 26, and protects the upper surface 31 of the thermally conductive material layer 26, which is superimposed on a battery pack 36 (described later). The material of the protective sheet 32 ​​is not particularly limited, but it is, for example, a synthetic resin film such as polyethylene, polypropylene, polyvinyl chloride, or polyester.

[0041] The filler layer 28 is formed, for example, from a filler made of a thermally conductive resin, in which a thermally conductive filler 34 with high thermal conductivity is mixed with a base material made of synthetic resin. The filler layer 28 hardens over time from a fluid state, for example, by contact with air, mixing with a curing agent, heating, light irradiation, or the like. The thermally conductive filler 34 of the filler layer 28 may be made of the same material as the thermally conductive filler 30 of the thermally conductive material layer 26, or may be made of a different material. However, it is preferable that the thermally conductive filler 34 be made of an electrically insulating material, preferably with an electrical insulation property of, for example, 10^8 Ω·cm or greater. The thermally conductive filler 34 preferably has a thermal conductivity of 2 W / K·m or greater, more preferably 10 W / K·m or greater. The thermally conductive filler 34 of the filler layer 28 does not need to be magnetic, but may be magnetic. The filler layer 28 may be formed, for example, from a base material made of a urethane-based or silicone-based resin, in which a thermally conductive filler such as aluminum oxide, magnesium oxide, or silicon nitride is mixed.

[0042] The filler layer 28 is provided so as to be interposed between the cooling surface 14 of the cooling plate body 12 and the thermally conductive material layer 26. For example, a fluid filler is applied to the cooling surface 14 so as to be thicker than the filler layer 28, and then the thermally conductive material layer 26, which is a pre-prepared molded product, is pressed against the cooling surface 14 to which the filler has been applied, thinning the filler to the thickness of the filler layer 28 and spreading it over the entire cooling surface 14. The layer of filler spread on the cooling surface 14 then hardens over time to form the filler layer 28, which is in close contact with the cooling surface 14 and the underside of the thermally conductive material layer 26. The filler layer 28 is not limited to a completely hardened filler; for example, when the cooling heat exchanger 10 is shipped as a finished product, the surface portion of the filler may be hardened but the interior may not be completely hardened.

[0043] It is desirable that the thermally conductive layer 26 be held pressed against the cooling surface 14, at least while the surface portion of the filler is hardening. This makes it easier for the filler to enter the gaps between the overlapping surfaces of the cooling surface 14 and the underside of the thermally conductive layer 26, and further adheres the cooling surface 14 and the underside of the thermally conductive layer 26 together, making it less likely that the thermal conductivity between the cooling surface 14 and the thermally conductive layer 26 will decrease due to gaps, ensuring high thermal conductivity.

[0044] In particular, unlike the thermally conductive material layer 26, which is molded in advance, the filler layer 28 is formed by hardening the filler from a fluid state, and therefore has high conformability to the cooling surface 14 and the underside of the thermally conductive material layer 26. Therefore, the filler layer 28 can be provided to precisely conform to, for example, minute irregularities on the cooling surface 14 and recesses caused by air bubbles 29 opening on the underside of the thermally conductive material layer 26, and high adhesion can be achieved between the cooling surface 14 and the underside of the thermally conductive material layer 26.

[0045] In this embodiment, the thermally conductive material layer 26 is thicker than the filler layer 28, and the thickness T2 of the thermally conductive material layer 26 is greater than the thickness T3 of the filler layer 28. The thickness T2 of the thermally conductive material layer 26 is preferably within a range of 1 to 30 mm, more preferably within a range of 1 to 10 mm. The thickness T3 of the filler layer 28 is preferably within a range of 0.05 to 10 mm, more preferably within a range of 0.05 to 2 mm. For ease of viewing, in FIGS. 1 and 2, the thicknesses of the cooling plate body 12, the thermally conductive material layer 26, and the filler layer 28 are exaggerated relative to their respective horizontal lengths, and their relative proportions are appropriately adjusted. Furthermore, the thicknesses T2 and T3 are the thicknesses of the cooling heat exchanger 10 alone, without the battery pack 36 (described later) attached.

[0046] At the time of shipping of the cooling heat exchanger 10 as a finished product, the thermally conductive material layer 26 is softer in the thickness direction (vertical direction) than the filler layer 28. The hardness of the thermally conductive material layer 26 and the filler layer 28 can be measured by various known testing methods, such as a Shore hardness test or a hardness test using a durometer. At the time of shipping of the cooling heat exchanger 10 as a finished product, the filler layer 28 of this embodiment has completely hardened, and has almost no elasticity and is essentially hard.

[0047] As shown in FIG. 2 , the cooling heat exchanger 10 configured as described above is used with a battery pack 36, as the object to be cooled, placed on the cooling surface 14, and cools the battery pack 36 by heat exchange between the cooling surface 14, which is cooled by a cooling heat medium flowing through the cooling flow path 20, and the battery pack 36.

[0048] The battery pack 36 has, for example, a rectangular parallelepiped outer shape and includes a pair of mounting pieces 38, 38 protruding from both the left and right sides. Each mounting piece 38, 38 is plate-shaped and has a screw hole 40 that penetrates vertically and has a screw thread formed on the inner circumferential surface. Note that in Figure 2, the internal structure of the battery pack 36 is not shown.

[0049] The battery pack 36 and the cooling heat exchanger 10 are interconnected by inserting bolts 42, 42 from below into the bolt insertion holes 18, 18 provided in the cooling plate body 12 of the cooling heat exchanger 10 and screwing them into the threaded holes 40, 40 of the mounting pieces 38, 38 in the battery pack 36.

[0050] A cooling surface covering layer 16 is interposed between the battery pack 36 and the cooling surface 14. The battery pack 36 is indirectly superimposed on the cooling surface 14 via the cooling surface covering layer 16. The battery pack 36 is superimposed in direct contact with the thermally conductive material layer 26 that constitutes the cooling surface covering layer 16. Note that the protective sheet 32 ​​covering the upper surface 31 of the thermally conductive material layer 26 is removed before the battery pack 36 is attached. Therefore, the upper surface 31 of the thermally conductive material layer 26 is directly superimposed on the lower surface of the battery pack 36 in a state where there is little foreign matter such as dust.

[0051] The cooling surface covering layer 16 is compressed in the vertical direction between the cooling surface 14 and the battery pack 36. In this embodiment, when the bolts 42 are fastened into the screw holes 40 of the mounting pieces 38 of the battery pack 36, the battery pack 36 is pressed against the upper surface 31 of the cooling surface covering layer 16, and a vertical compressive force acts on the cooling surface covering layer 16.

[0052] In the filler layer 28 of this embodiment, the curing reaction of the filler is completed, and the filler layer 28 has low elasticity and is substantially hard, so that the filler layer 28 is hardly deformed by the compressive force acting when the battery pack 36 is attached. However, the filler layer 28 may be hard enough to be deformed by the compressive force acting when the battery pack 36 is attached.

[0053] In this embodiment, the thermally conductive material layer 26 in the cooling surface covering layer 16 is thicker and softer than the filler layer 28, and when the cooling surface covering layer 16 is compressed in the vertical direction by the attachment of the battery pack 36, it is mainly the thermally conductive material layer 26 that deforms and becomes thinner in the vertical direction. The thermally conductive material layer 26 is able to conform to the shape of the lower surface of the battery pack 36, and is superimposed on the lower surface of the battery pack 36 in a state of intimate contact.

[0054] Furthermore, the force exerted on the cooling heat exchanger 10 by tightening the bolts 42, 42 is transmitted at a reduced rate to the cooling plate body 12 by the buffering effect based on the elasticity of the thermally conductive material layer 26. Therefore, when assembling the battery pack 36, a large force caused by tightening the bolts 42, 42 is unlikely to act on the cooling plate body 12, and damage such as cracking of the cooling plate body 12 is avoided.

[0055] In this embodiment, the thermally conductive material layer 26 is a foam, which has a larger compressibility in the vertical direction than a solid body made of the same material. Therefore, even when the filler layer 28 is barely deformed, it can advantageously conform to the shape of the underside of the battery pack 36 and cushion the pressure of the battery pack 36. Note that the compression, compressive deformation, and compressibility of the filler layer and the thermally conductive material layer in this invention refer to dimensional reduction due to pressure in one direction, i.e., the overlapping direction of the cooling surface and the cooling target, and are not limited to compression in the strict sense, which refers to volume reduction. For example, the filler layer may be made of a material that is substantially incompressible (Poisson's ratio of approximately 0.5).

[0056] In the cooling heat exchanger 10 in use with a battery pack 36 attached, a low-temperature cooling heat medium (refrigerant) is supplied to the cooling flow path 20, thereby lowering the temperature of the cooling surface 14. Heat is exchanged between the cooling surface 14 and the battery pack 36, which is a heat-generating body, via the cooling surface coating layer 16, thereby cooling the battery pack 36. The cooling flow path 20 is connected to an external flow path (not shown), and the refrigerant circulates through a flow path consisting of the cooling flow path 20 and the external flow path. The external flow path is provided with a cooling device, such as an air-cooling device or a liquid-cooling device, such as a refrigerator or radiator. The refrigerant, which has reached a high temperature through heat exchange with the battery pack 36, is cooled by the cooling device and supplied from the external flow path to the cooling flow path 20.

[0057] The thermally conductive material layer 26 and the filler layer 28 that constitute the cooling surface covering layer 16 are blended with thermally conductive fillers 30, 34, and are set to have sufficiently high thermal conductivity. Therefore, even if the thermally conductive material layer 26 and the filler layer 28 are interposed between the cooling surface 14 and the battery pack 36, a sufficiently high heat exchange efficiency is achieved between the cooling surface 14 and the battery pack 36.

[0058] In particular, in this embodiment, the thermally conductive filler 30 of the thermally conductive material layer 26 is oriented in the thickness direction (vertical direction) of the thermally conductive material layer 26, which is the overlapping direction of the cooling surface 14 and the battery pack 36, so that the thermal conductivity in the thickness direction of the thermally conductive material layer 26 is greater than in other directions. Therefore, more efficient heat exchange is achieved between the cooling surface 14 and the battery pack 36, which are overlapped via the thermally conductive material layer 26.

[0059] The cooling heat exchanger 10 can be manufactured by the following process.

[0060] That is, first, the first plate 22 and the second plate 24 are prepared, and then the first plate 22 and the second plate 24 are stacked together to form the cooling plate body 12. The first and second plates 22, 24 can be obtained, for example, by press forming or molding a flat metal plate. The first and second plates 22, 24 are fixed to each other in a stacked state by means of welding, adhesive, or the like.

[0061] Next, a process for forming the thermally conductive material layer 26 is performed. The thermally conductive material layer 26 is formed by molding an elastic material mixed with thermally conductive fillers 30. Since the thermally conductive material layer 26 of this embodiment is a foam having numerous closed cells 29 formed therein, for example, a foaming agent is mixed into the elastic material before molding. Furthermore, in this embodiment, in order to improve the thermal conductivity of the thermally conductive material layer 26 in the thickness direction, a magnetic force is applied in the thickness direction during molding of the thermally conductive material layer 26, thereby orienting the thermally conductive fillers 30, which are magnetic bodies, so that they align in the thickness direction of the thermally conductive material layer 26. In other words, the thermally conductive fillers 30 align in the thickness direction of the thermally conductive material layer 26 along the magnetic field lines of the magnetic field applied during molding of the thermally conductive material layer 26, so that the average distance between the thermally conductive fillers 30 in the thickness direction is shorter than the average distance between the thermally conductive fillers 30 in the direction perpendicular to the thickness direction. After the thermally conductive layer 26 is formed, the protective sheet 32 ​​can be attached to the upper surface 31 of the thermally conductive layer 26 to protect the upper surface 31 of the thermally conductive layer 26 with the protective sheet 32 ​​.

[0062] Next, a step is performed in which a thermally conductive filler is placed on the cooling surface 14 of the cooling plate body 12 by squeezing or the like. The filler is formed by mixing a thermally conductive filler 34 into a synthetic resin base material, and is in the form of a soft paste or the like having fluidity that allows it to be spread over the cooling surface 14. The filler has a cross-sectional shape with vertical dimensions larger than those of the filler layer 28, and is arranged on the cooling surface 14 so as to extend, for example, in a serpentine shape.

[0063] Next, a process is performed in which the thermally conductive material layer 26 is placed over the filler on the cooling surface 14 from above, and the filler is hardened while being compressed vertically between the cooling surface 14 and the thermally conductive material layer 26, thereby forming a filler layer 28 between the overlapping surfaces of the cooling surface 14 and the thermally conductive material layer 26. The filler layer 28 is formed by compressing the filler vertically between the cooling surface 14 and the thermally conductive material layer 26 to form a layer. Therefore, the bottom surface of the filler layer 28 is in close contact with the cooling surface 14, and the top surface is in close contact with the thermally conductive material layer 26, filling the gap between the overlapping surfaces of the cooling surface 14 and the thermally conductive material layer 26. The filler layer 28 hardens over time, for example, through contact with air, a chemical reaction due to mixing with a curing agent, heating, light irradiation, etc. In this embodiment, the hardening reaction of the filler layer 28 is completed at least by the time the cooling heat exchanger 10 is shipped as a finished product. Furthermore, the filler layer 28 of this embodiment is fixed to the cooling surface 14 and the thermally conductive material layer 26 by hardening, and also functions as an adhesive that bonds the cooling surface 14 and the thermally conductive material layer 26 together.

[0064] The manufacturing method of the cooling heat exchanger 10 according to this embodiment includes the above-described steps. According to this manufacturing method of the cooling heat exchanger 10, the space between the cooling surface 14 and the thermally conductive material layer 26 is filled with the filler layer 28, thereby achieving high thermal conductivity between the cooling surface 14 and the thermally conductive material layer 26.

[0065] Figure 3 shows a cooling heat exchanger 50 according to a second embodiment of the present invention. The cooling heat exchanger 50 has a structure in which a cooling surface coating layer 52 is provided on the cooling surface 14 of the cooling plate body 12. In the following description, components and parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals in the figures, and description thereof will be omitted. Also, in Figures 3 and 4, as in Figures 1 and 2, thickness dimensions are exaggerated, and the thickness ratios of each part are appropriately changed.

[0066] The cooling surface covering layer 52 is configured to include a heat conductive material layer 54 and a filler layer 56. Note that the materials forming the heat conductive material layer 54 and the filler layer 56 are the same as those in the first embodiment, and therefore, a description thereof will be omitted here.

[0067] In the cooling surface covering layer 52 of this embodiment, the filler layer 56 is thicker than the thermally conductive material layer 54, and the thickness T5 of the filler layer 56 is greater than the thickness T4 of the thermally conductive material layer 54. In this embodiment, the thickness T4 of the thermally conductive material layer 54 is preferably within the range of 1 to 10 mm, and more preferably within the range of 1 to 2 mm. The thickness T5 of the filler layer 56 is preferably within the range of 3 to 30 mm, and more preferably within the range of 3 to 10 mm. Note that the thicknesses T4 and T5 are the thicknesses of the cooling heat exchanger 50 alone, without the battery pack 36 attached.

[0068] The cooling heat exchanger 50 according to this embodiment can be obtained by substantially the same manufacturing method as the cooling heat exchanger 10 according to the first embodiment. Furthermore, when the cooling heat exchanger 50 is shipped as a finished product, the filler layer 56 is softer in the thickness direction (vertical direction) than the thermally conductive material layer 54. When the cooling heat exchanger 50 is shipped as a finished product, the filler layer 56 of this embodiment has not yet hardened, and has elasticity in the vertical direction. Furthermore, when the cooling heat exchanger 50 is shipped as a finished product, the elasticity of the filler layer 56 in the vertical direction is greater than the elasticity of the thermally conductive material layer 54 in the vertical direction.

[0069] The filler layer 56 of this embodiment is formed, for example, of a one-component filler that hardens upon contact with air. Furthermore, the filler layer 56 is covered on both the top and bottom surfaces by the cooling surface 14 and the thermally conductive material layer 54, reducing the filler layer 56's exposure to the external space. Furthermore, the outer peripheral surface of the filler layer 56 is covered by a hardening adjustment sheet 58. The hardening adjustment sheet 58 is formed of a synthetic resin film or the like that restricts air passage. By limiting contact between the outer peripheral surface of the filler layer 56 and air, the hardening rate of the filler layer 56 is slowed. In this way, the filler layer 56 of this embodiment is prevented from contacting air on both the top and bottom surfaces by the cooling surface 14 of the cooling plate body 12 and the thermally conductive material layer 54, and the outer peripheral surface is prevented from contacting air by the hardening adjustment sheet 58. This extends the hardening time of the filler layer 56, allowing the filler layer 56 to maintain its flexibility for a longer period of time. Therefore, even if a relatively long period of time, such as several days, passes between the formation of the filler layer 56 and the shipping of the cooling heat exchanger 50 as a product, the elasticity of the filler layer 56 can be effectively obtained. The hardening adjusting sheet 58 also covers the outer peripheral surface of the thermally conductive material layer 54, and also functions as a protective sheet that prevents foreign matter from adhering to the outer peripheral surfaces of the filler layer 56 and the thermally conductive material layer 54. However, the hardening adjusting sheet 58 may cover only the outer peripheral surface of the filler layer 56 without covering the outer peripheral surface of the thermally conductive material layer 54.

[0070] In the cooling heat exchanger 50 of this embodiment having such a structure, similar to the cooling heat exchanger 10 of the first embodiment, the battery pack 36 is indirectly placed on the cooling surface 14 of the cooling plate body 12 via the cooling surface covering layer 52, as shown in FIG. 4 . When the battery pack 36 is installed, the filler layer 56 is not completely hardened and retains elasticity, more preferably greater elasticity than the thermally conductive material layer 54. The time from the start of hardening of the filler layer 56 to the installation of the battery pack 36 is preferably within two weeks, more preferably within one week. Note that the protective sheet 32 ​​and hardening adjustment sheet 58 are both removed before the battery pack 36 is installed in the cooling heat exchanger 50.

[0071] By tightening the bolts 42, 42, the battery pack 36 is pressed downward against the cooling surface 14 and the cooling surface covering layer 52. As a result, the thermally conductive material layer 54 and the filler material layer 56 that constitute the cooling surface covering layer 52 are both compressed in the vertical direction between the battery pack 36 and the cooling surface 14. The cushioning effect caused by the compressive deformation of the thermally conductive material layer 54 and the filler material layer 56 reduces the forces acting on the cooling plate main body 12 and the battery pack 36 due to tightening of the bolts 42, 42 when assembling the battery pack 36, thereby preventing damage to the cooling plate main body 12 and the battery pack 36.

[0072] In this embodiment, the filler layer 56 is thicker and softer than the thermally conductive material layer 54, and therefore both the thermally conductive material layer 54 and the filler material layer 56 deform in response to the input force generated when the battery pack 36 is attached, with the filler material layer 56 deforming more than the thermally conductive material layer 54. In this way, both the thermally conductive material layer 54 and the filler material layer 56 that constitute the cooling surface covering layer 52 have elasticity that allows for compressive deformation, making it easier to obtain a greater cushioning effect when the battery pack 36 is attached.

[0073] Because the filler layer 56 hardens from the surface that is most exposed to air, if the thermally conductive material layer 54 were not present, the exposed upper surface would harden, which would likely create a gap between the battery pack 36 and the filler layer 56, potentially reducing the efficiency of heat exchange between the battery pack 36. In the cooling heat exchanger 50, even if the upper surface of the filler layer 56 hardens, the elastic thermally conductive material layer 54 is provided above the filler layer 56, so the gap between the battery pack 36 and the filler layer 56 is filled with the thermally conductive material layer 54, preventing a reduction in heat exchange efficiency due to the gap.

[0074] 5 shows a cooling heat exchanger 60 according to a third embodiment of the present invention. The cooling heat exchanger 60 includes a thermally conductive material layer 62. Note that the cooling heat exchanger 60 will not be described in detail if it is substantially the same as the cooling heat exchanger 10 according to the first embodiment. The manufacturing method for the cooling heat exchanger 60 is substantially the same as the manufacturing method for the cooling heat exchanger 10.

[0075] The thermally conductive material layer 62 has a convex upper surface 64, which is the surface that comes into contact with the battery pack (36). That is, the upper surface 64 of the thermally conductive material layer 62 is shaped to slope downward from the apex toward the outer periphery, and in this embodiment, slopes downward from the center in the front-to-back and left-to-right directions toward the outer periphery. The upper surface 64 of the thermally conductive material layer 62 may slope downward at a substantially constant angle toward the outer periphery, but in this embodiment, it is shaped as a curved convex surface whose slope angle gradually increases toward the outer periphery.

[0076] In the cooling heat exchanger 60 configured according to this embodiment, the upper surface 64 of the thermally conductive material layer 62 is formed as a convex surface. Therefore, when the battery pack (36) is pressed against the upper surface 64 of the thermally conductive material layer 62, the contact area between the lower surface of the battery pack (36) and the upper surface 64 of the thermally conductive material layer 62 gradually expands from the apex of the upper surface 64 toward the periphery. Therefore, air between the overlapping surfaces of the upper surface 64 of the thermally conductive material layer 62 and the battery pack (36) is pushed outward, making it difficult for air to remain between the overlapping surfaces of the upper surface 64 and the battery pack (36). This prevents a decrease in heat exchange efficiency between the battery pack (36) and the thermally conductive material layer 62 due to the presence of air.

[0077] The shape of the upper surface 64 of the thermally conductive material layer 62 for preventing air from remaining between the overlapping surfaces of the battery pack (36) is not limited to the convex surface that slopes downward from the inner periphery to the outer periphery as shown in this embodiment. Specifically, the effect of suppressing air from remaining can also be expected by using an upper surface of the thermally conductive material layer that slopes downward from one side to the other, or a gabled shape that slopes downward from the middle of the left and right to both the left and right sides.

[0078] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions. For example, the number, size, shape, etc. of the cooling surfaces 14 provided on the cooling plate body 12 are not limited.

[0079] The thermally conductive filler of the thermally conductive material layer is not limited to a magnetic material. For example, if a non-magnetic thermally conductive filler is used, it is not necessary to apply a magnetic field during molding of the thermally conductive material layer. Furthermore, the thermally conductive filler of the thermally conductive material layer does not have to have electrical insulation. Furthermore, the thermally conductive material layer is not limited to a foam. Note that, like the thermally conductive filler of the thermally conductive material layer, the thermally conductive filler of the filling material layer does not have to have magnetic or electrical insulation properties.

[0080] The connection structure between the cooling heat exchanger 10 and the battery pack 36 is not limited to the fastening structure using the bolts 42 shown in the first and second embodiments, and various connection structures using mechanical locking or the like can be employed, such as a structure in which separate hooks are used to connect both left and right ends of the cooling plate body 12 of the cooling heat exchanger 10 to the mounting pieces 38 of the battery pack 36. Furthermore, in the first and second embodiments, the cooling heat exchanger 10 and the battery pack 36 are connected by forming threaded holes 40 in the mounting pieces 38 and threading the bolts 42 into the threaded holes 40, but the connection structure between the cooling heat exchanger 10 and the battery pack 36 can also be configured by, for example, forming through holes without threads on the inner circumferential surfaces of the mounting pieces 38 and threading nuts onto the bolts 42 inserted into the through holes.

[0081] It is desirable to provide the protective sheet 32 ​​when the upper surface 31 of the thermally conductive material layer 26 is adhesive, but this is not essential, and the protective sheet can be omitted, for example, when dust and the like are unlikely to adhere to the upper surface 31 of the thermally conductive material layer 26.

[0082] In the second embodiment, the protective sheet 32 ​​covering the upper surface 31 of the thermally conductive material layer 54 and the hardening adjustment sheet 58 covering the outer peripheral surfaces of the thermally conductive material layer 54 and the filler layer 56 are formed as separate independent sheets, but the protective sheet and hardening adjustment sheet can also be integrally formed as a single sheet.

[0083] REFERENCE SIGNS LIST 10 Cooling heat exchanger (first embodiment) 12 Cooling plate body 14 Cooling surface 16 Cooling surface covering layer 18 Bolt insertion hole 20 Cooling flow path 22 First plate 24 Second plate 26 Thermally conductive material layer 28 Filler layer 29 Air bubbles 30 Thermally conductive filler 31 Upper surface 32 Protective sheet 34 Thermally conductive filler 36 Battery pack (cooling target) 38 Mounting piece 40 Screw hole 42 Bolt 50 Cooling heat exchanger (second embodiment) 52 Cooling surface covering layer 54 Thermally conductive material layer 56 Filler layer 58 Hardening adjustment sheet 60 Cooling heat exchanger (third embodiment) 62 Thermally conductive material layer 64 Upper surface

Claims

1. A cooling heat exchanger in which a cooling medium flows through a cooling flow path formed inside to cool an object to be cooled that is placed on a cooling surface provided on the surface, wherein a thermally conductive layer is arranged on the cooling surface, and the thermally conductive layer is a thermally conductive elastic body made of a molded elastic material containing a thermally conductive filler, and between the overlapping surfaces of the cooling surface and the thermally conductive layer, a thermally conductive filler layer is provided that is in close contact with each of the overlapping surfaces of the cooling surface and the thermally conductive layer.

2. A cooling heat exchanger according to claim 1, further comprising a hardening control sheet covering the outer peripheral surface of said filler layer to inhibit the hardening reaction of said filler layer.

3. A heat exchanger for cooling according to claim 1 or 2, wherein a large number of said thermally conductive fillers are oriented so as to form a heat transfer path within said thermally conductive material layer.

4. A heat exchanger for cooling according to any one of claims 1 to 3, wherein the thermally conductive layer is a foam.

5. A cooling heat exchanger according to any one of claims 1 to 4, wherein the thermally conductive layer is thicker and softer than the filler layer.

6. A cooling heat exchanger according to any one of claims 1 to 4, wherein the filler layer is thicker and softer than the thermally conductive layer.

7. A heat exchanger for cooling according to any one of claims 1 to 6, wherein the surface of said thermally conductive material layer that comes into contact with said object to be cooled is a convex surface.

8. A method for manufacturing a cooling heat exchanger in which a cooling medium flows through a cooling flow path formed inside to cool an object to be cooled that is placed over a cooling surface provided on the surface, the method comprising the steps of: preparing a heat conductive layer by molding an elastic material mixed with a heat conductive filler; placing a soft, heat conductive filler on the cooling surface; and overlaying the heat conductive layer on the soft filler placed on the cooling surface, compressing and hardening the filler between the cooling surface and the heat conductive layer to form a filler layer between the overlapping surfaces of the cooling surface and the heat conductive layer, and bringing the filler layer into close contact with each of the overlapping surfaces of the cooling surface and the heat conductive layer.

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