Cooling structure

Abstract

A cooling structure forming a refrigerant flow path for refrigerant to circulate internally, the cooling structure comprising: a fin base thermally connected to a heat-dissipating component and having a plurality of heat dissipation fins; a frame having an opening liquid-tightly sealed by the fin base and holding the fin base in a manner capable of relative displacement along the vertical orientation of the plurality of heat dissipation fins; and a flow path cover covering the fin base and liquid-tightly bonded to the frame on the outer periphery of the fin base, wherein the flow path cover has a curved portion with a radius of curvature of more than a predetermined value at a position opposite to the front end of the outermost heat dissipation fin among the plurality of heat dissipation fins, the flow path cover having a pressing portion recessed towards the fin base side compared to the apex of the curved portion and abutting against the front end of a portion of the plurality of heat dissipation fins, and in a cross section orthogonal to the refrigerant flow direction, the flow path cover having a plurality of inflection points between the curved portion and the pressing portion.

Description

Technical Field

[0001] This invention relates to a cooling structure. Background Technology

[0002] Power conversion devices that switch between DC and AC power via the switching action of semiconductor elements are widely used in electric vehicles and hybrid vehicles. The semiconductor elements within these power conversion devices generate heat due to the switching action, requiring the cooling structure of the device to have high heat dissipation performance. Power modules with built-in semiconductor elements have heat dissipation components to cool the heat generated from the semiconductor elements. These heat dissipation components have heat dissipation fins, and as a cooling structure, water channels are formed through the heat dissipation fins. Patent Document 1 discloses a semiconductor element comprising: multiple power modules having semiconductor elements; multiple heat dissipation bases arranged on the heat dissipation surfaces of the multiple power modules via heat dissipation components and having heat dissipation fins; a frame having multiple openings; and a cover that forms a refrigerant flow path by covering the heat dissipation bases and the frame, wherein the multiple heat dissipation bases respectively block the multiple openings, and the cover has an elastic force-applying portion at the surface in contact with the heat dissipation fins, applying force to the heat dissipation bases by pressurizing towards the power modules.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2023-073861. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the invention described in Patent Document 1, there is room for improvement in the cooling structure.

[0008] Solution for solving the problem

[0009] According to a first aspect of the invention, a cooling structure is a cooling structure that forms a refrigerant flow path for internal refrigerant circulation. The cooling structure comprises: a fin base thermally connected to a heat-dissipating component and having a plurality of heat-dissipating fins; a frame having an opening liquid-tightly sealed by the fin base and holding the fin base in a manner capable of relative displacement along the vertical orientation of the plurality of heat-dissipating fins; and a flow path cover covering the fin base and liquid-tightly coupled to the frame on the outer periphery of the fin base. The flow path cover has a curved portion with a radius of curvature greater than a predetermined value at a position opposite to the front end of the outermost heat-dissipating fin among the plurality of heat-dissipating fins. The flow path cover has a pressing portion recessed towards the fin base side compared to the apex of the curved portion and abutting against the front end of a portion of the plurality of heat-dissipating fins. In a cross-section orthogonal to the refrigerant flow direction, the flow path cover has a plurality of inflection points between the curved portion and the pressing portion.

[0010] Invention Effects

[0011] According to the present invention, the heat dissipation performance of the cooling structure can be improved. Attached Figure Description

[0012] Figure 1 It is an exploded 3D view of a power conversion device.

[0013] Figure 2 This is a cross-sectional view showing the cooling structure of the power conversion device.

[0014] Figure 3 This is a cross-sectional view showing the cooling structure of the power conversion device.

[0015] Figure 4 This is a cross-sectional view of a comparative example power conversion device.

[0016] Figure 5 This is a diagram illustrating the manufacturing method of the power conversion device in the second embodiment.

[0017] Figure 6 This is a diagram showing the cooling structure of the power conversion device in the third embodiment.

[0018] Figure 7 This is a diagram showing the cooling structure of the power conversion device in the fourth embodiment. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention and have been appropriately omitted and simplified for clarity. The present invention may also be implemented in various other ways. Unless specifically limited, each component may be single or multiple. For ease of understanding, the positions, sizes, shapes, extents, etc., of the components shown in the drawings may not represent actual positions, sizes, shapes, extents, etc. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, extents, etc., disclosed in the drawings.

[0020] First Implementation Method

[0021] The following will refer to Figures 1 to 4 The first embodiment of the cooling structure will be described.

[0022] Figure 1 This is an exploded perspective view of the power conversion device 1. The power conversion device 1 includes a power module 2, a heat dissipation component 3, a frame 4, and a flow path cover 5. Figure 1 In the example shown, the power conversion device 1 has 24 power modules 2 arranged in a 4 x 6 configuration. The power modules 2 are mounted on a substrate 6. In addition to the power modules 2, the substrate 6 also contains electronic components, positioning holes, and mounting bosses, etc. Figure 1 The diagram is omitted. Because power module 2 generates a significant amount of heat, it requires heat dissipation for stable operation. The power conversion device 1 has a cooling structure for cooling power module 2. Since power module 2 requires heat dissipation, it is also referred to as the "heat-dissipated component".

[0023] In power module 2, semiconductor components or wires are sealed with sealing material to house them, but... Figure 1 The illustration of the sealing material is omitted. Additionally, insulating material is provided inside or outside the power module 2, but... Figure 1 The diagram of the insulating material is omitted. The two sides of the power module 2 are heat dissipation surfaces for dissipating heat caused by the switching action of the semiconductor components. Heat-conducting components 7, such as thermally conductive grease or thermally conductive sheets, are provided on both sides of the power module 2 (see reference). Figure 2 ).

[0024] The heat dissipation component 3 includes a fin base 31 and a plurality of heat dissipation fins 32. One heat dissipation component 3 is provided for every four power modules 2, for a total of six heat dissipation components 3. The fin base 31 is thermally connected to the heat dissipation surface of the power module 2, which is the component being dissipated, via a heat conduction component 7. Furthermore, although the heat dissipation fins 32 are illustrated as cylindrical needle-shaped fins, they can be other shapes; the shape of the heat dissipation fins 32 is not limited.

[0025] The frame 4 has the same number of openings 41 as the heat dissipation components 3, and the heat dissipation components 3 are fitted into these openings 41. (Refer to...) Figure 2 and Figure 3 The details of the heat dissipation component 3 being fitted into the opening 41 will be described. The flow path cover 5 forms a closed space by covering the heat dissipation component 3 and the frame 4. Hereinafter, this closed space will be referred to as the refrigerant flow path. The flow path cover 5 has an inlet pipe 93 and an outlet pipe 94, from which the refrigerant flows, i.e., from left to right as shown in the figure. The refrigerant passes through the heat dissipation fins 32, thereby enabling efficient heat transfer from the heat dissipation fins 32 towards the refrigerant. Further details will follow. Figure 2 and Figure 3 Details of the flow path cover 5 are explained below. Figure 1 Although the lower side of substrate 6 is not shown in the exploded perspective view, it has a refrigerant flow path formed similarly to the upper side. The refrigerant flow paths on the upper and lower sides are connected by a connecting pipe 95.

[0026] Furthermore, the power conversion device 1 shows an example of 24 (4 x 6 groups) power modules 2 arranged together, but the number of power modules 2 is arbitrary. Additionally, although this embodiment describes an example where the heat dissipation component 3 is arranged on both sides of the power module 2, it is also possible to arrange the heat dissipation component 3 on only one side of the power module 2. In this case, a frame or mounting component is arranged on the other side of the power module 2, and the other side of the power module 2 is fixed to the frame or mounting component by a fixing component.

[0027] Figure 2 and Figure 3 This is a cross-sectional view showing the cooling structure of the power conversion device 1. Figure 2 yes Figure 1 The II-II sectional view is illustrated through a section parallel to the direction of refrigerant flow. Figure 3 yes Figure 1 and Figure 2 The III-III sectional view is illustrated through a section orthogonal to the refrigerant flow direction. Figure 2 The image shows the state in which the heat dissipation component 3, frame 4, flow path cover 5, etc., are assembled on both sides of the power module 2 via the heat conduction component 7. Figure 3 The image shows the state in which the heat dissipation component 3, frame 4, flow path cover 5, etc. are assembled on both sides of the power module 2 via the heat conduction component 7.

[0028] The flow path cover 5 and the frame 4 are joined at the joint 10 on the outer periphery of the fin base 31 by brazing or the like, ensuring their respective liquid tightness. In addition, similar to the joint 10, a fastening part 11 is provided on the outer periphery of the fin base 31 and is fastened with bolts or the like, so that the frame 4 and the flow path cover 5 are held on the upper and lower parts of the substrate 6.

[0029] The fin base 31 is fitted into the opening 41 of the frame 4 via the first sealing member 81, thereby ensuring liquid tightness. The first sealing member 81 is an elastic member such as a liquid seal, and the fin base 31 is elastically supported relative to the frame 4. That is, the fin base 31 is held in a manner that allows it to be displaced relative to the vertical direction of the heat dissipation fins 32, i.e., the up-down direction shown in the figure.

[0030] With the structure described above, refrigerant flow paths 90, which cover the heat dissipation component 3 and the frame 4 with flow path cap 5, are formed on the upper and lower surfaces of the substrate 6, respectively. The refrigerant flow path 90 includes an upper flow path 91 and a lower flow path 92. The flow path cap 5 on the upper side of the substrate 6 is provided with an inlet pipe 93 that serves as a refrigerant inlet, and an outlet pipe 94 that serves as a refrigerant outlet is provided on the opposite side of the inlet pipe 93. Furthermore, a connecting pipe 95 is connected to the upper flow path 91 and the lower flow path 92, ensuring a liquid-tight seal through a second sealing component 82 such as an O-ring.

[0031] Refrigerant is supplied from inlet pipe 93 via a pump (not shown) and distributed to upper flow path 91 and lower flow path 92 via connecting pipe 95. The distributed refrigerant passes through heat dissipation fins 32, flows from lower flow path 92 through connecting pipe 95 and merges again into upper flow path 91, and is discharged from outlet pipe 94. However, the refrigerant flow described herein is only one example and is not limited thereto.

[0032] like Figure 3 As shown, the flow path cover 5 has a curved portion 51 at a position opposite to the front end of the outermost fin of the plurality of heat dissipation fins 32. Additionally, the flow path cover 5 has a pressing portion 52 that abuts against the front end of a portion of the heat dissipation fins 32. The height of the heat dissipation fins 32 is approximately constant, and the spacing between the heat dissipation fins 32 and the flow path cover 5 is determined by the shape of the flow path cover 5. The pressing portion 52 is a convex shape that is recessed towards the fin base 31 by a predetermined value or more compared to the apex of the curved portion 51. The flow path cover 5 is, for example, an elastic component made of aluminum, and is fastened at the fastening portion 11 with bolts or the like, thereby applying a fastening force from above and below in the direction toward the power module 2.

[0033] The pressing portion 52 of the flow path cover 5 presses against the front end of the heat dissipation fin 32, and applies force to the heat dissipation component 3 toward the heat dissipation surface of the power module 2. Through this force, surface pressure is applied to the heat conduction component 7 from the fin base 31. Because the bent portion 51 is given a reaction force when pressing the front end of the aforementioned heat dissipation fin 32, the bent portion 51 has a radius of curvature greater than a predetermined value in order to suppress local stress concentration in the bent portion 51. According to this configuration, in Figure 3In the cross-section shown orthogonal to the refrigerant flow direction, a bypass section 96 is formed between the curved portion 51 and pressing portion 52 of the flow path cover 5 and the front ends of the plurality of heat dissipation fins 32. A portion of the refrigerant flows into the bypass section 96 without passing through the space between the plurality of heat dissipation fins 32.

[0034] exist Figure 3 In the cross-section shown orthogonal to the refrigerant flow direction, the flow path cover 5 has a first inflection point 53a, a second inflection point 53b, and a third inflection point 53c between the curved portion 51 and the pressing portion 52. An inflection point is the point where the cross-section of the flow path cover, viewed from a section orthogonal to the refrigerant flow direction, switches between an upward and downward convex shape when considered as a curve. The presence of multiple inflection points indicates that the flow path cover 5 has a multi-level structure, which has a shape with multiple upward and downward bends or multiple levels of recesses. The first inflection point 53a to the third inflection point 53c are closer to the front end of the heat dissipation fins 32 than the apex of the curved portion 51.

[0035] The effects of this embodiment will be explained. In this embodiment, the flow path cover 5 has a first inflection point 53a, a second inflection point 53b, and a third inflection point 53c between the curved portion 51 and the pressing portion 52. These three inflection points are closer to the front ends of the plurality of heat dissipation fins 32 than the apex of the curved portion 51. Therefore, the cross-sectional area of ​​the bypass portion 96 formed between the curved portion 51 and the pressing portion 52 of the flow path cover 5 and the front ends of the plurality of heat dissipation fins 32 can be reduced. Since the refrigerant passing through the bypass portion 96 does not contribute to the heat dissipation generated from the power module 2, the heat dissipation performance deteriorates when the amount of refrigerant passing through the bypass portion 96 increases. By reducing the cross-sectional area of ​​the bypass portion 96, the flow resistance of the bypass portion 96 increases, the amount of refrigerant passing through the bypass portion 96 decreases, and correspondingly, the amount of refrigerant passing through the plurality of heat dissipation fins 32 increases. As a result, the heat dissipation performance of the cooling structure of the power conversion device 1 can be improved.

[0036] Other effects of this embodiment will be explained. In this embodiment, the pressing portion 52 is configured as a convex shape that is recessed by a predetermined value or more towards the fin base 31 compared to the apex of the bending portion 51. Therefore, the following performance regarding thickness deviations of the power module 2 is improved. Therefore, even for heat conduction components 7 provided on multiple power modules 2 with thickness deviations, uniform and large surface pressure can be applied to each. Therefore, the thickness of the heat conduction component 7 can be reduced to below a predetermined value, and the thermal resistance of the heat conduction component 7 can be reduced. As a result, the heat dissipation performance of the cooling structure of the power conversion device 1 can be improved.

[0037] Figure 4 This is a cross-sectional view of the comparative example power conversion device 1Z, which serves as a comparative example. Figure 4 and Figure 3The perspective is the same. The comparative power conversion device 1Z has a structure similar to that of power conversion device 1, but it lacks the first inflection point 53a, the second inflection point 53b, and the third inflection point 53c. Because the comparative power conversion device 1Z lacks these inflection points, the cross-sectional area of ​​the bypass section 96 is larger than that of the power conversion device 1. Therefore, the heat dissipation performance of the cooling structure of the comparative power conversion device 1Z is lower than that of the power conversion device 1.

[0038] In contrast, the flow path cover 5 of this embodiment has multiple inflection points between the curved portion 51 and the pressing portion 52, namely a first inflection point 53a, a second inflection point 53b, and a third inflection point 53c. By making the first inflection point 53a to the third inflection point 53c closer to the front end of the multiple heat dissipation fins 32 than the apex of the curved portion 51, the cross-sectional area of ​​the bypass portion 96 can be reduced.

[0039] According to the first embodiment described above, the following effects are obtained.

[0040] (1) The cooling structure of the power conversion device 1 forms a refrigerant flow path for the refrigerant to circulate internally. The power conversion device 1 includes: a fin base 31, which is thermally connected to a power module 2, which is a heat dissipation component, and has a plurality of heat dissipation fins 32; a frame 4, which has an opening 41 that is liquid-tightly sealed by the fin base 31, and holds the fin base 31 in a manner that allows relative displacement along the vertical arrangement direction of the plurality of heat dissipation fins 32; and a flow path cover 5, which covers the fin base 31 and is liquid-tightly bonded to the frame 4 on the outer periphery of the fin base 31. The flow path cover 5 has a curved portion 51 with a radius of curvature of more than a predetermined value at a position opposite to the front end of the outermost heat dissipation fin among the plurality of heat dissipation fins. The flow path cover 5 has a pressing portion 52, which is recessed toward the fin base side compared to the apex of the curved portion 51 and abuts against the front end of a portion of the heat dissipation fins among the plurality of heat dissipation fins. In a cross-section orthogonal to the refrigerant flow direction, the flow path cover 5 has multiple inflection points between the bend 51 and the pressing part 52. Therefore, by reducing the cross-sectional area of ​​the bypass part 96, the amount of refrigerant passing through the multiple heat dissipation fins 32 increases, thereby improving the heat dissipation performance of the cooling structure of the power conversion device 1.

[0041] (Variation Example 1)

[0042] In the first embodiment described above, the fastening portions 11, which are located at both ends of the upper and lower flow path covers 5 and are separated by the frame 4, are fastened with bolts or the like. However, instead of fastening the fastening portions 11, the central portion of the flow path cover 5 can be pressed towards the substrate 6 using a leaf spring or the like. For example, Figure 3 The upper flow path cover 5 in the middle diagram is pressed downwards, and the lower flow path cover 5 in the middle diagram is pressed upwards.

[0043] Second Implementation Method

[0044] Reference Figure 5 A second embodiment of the cooling structure will be described below. In the following description, the same reference numerals are used to denote the same components as in the first embodiment, and the main differences are explained. Points not specifically described are the same as in the first embodiment. The main difference between this embodiment and the first embodiment is that a method for manufacturing the power conversion device is specified.

[0045] Figure 5 This is a diagram illustrating the manufacturing method of the power conversion device 1A in the second embodiment. Figure 5 Compared with the first embodiment Figure 3 Same perspective. Figure 5 The upper figure shows the state before fastening with bolts or the like, and the lower figure shows the state after fastening with bolts or the like at the fastening part 11. In this embodiment, fastening is performed at the fastening part 11, thereby applying a fastening force from above and below in the direction toward the power module 2. While the first sealing member 81 is pressed and deformed, the fastening part 11 and the frame 4 are displaced toward the substrate 6. On the other hand, the pressing part 52 abuts against and presses against the plurality of heat dissipation fins 32, applying force to the heat dissipation surface of the heat dissipation member 3 toward the heat dissipation surface of the power module 2, and applying surface pressure to the heat conduction member 7 from the fin base 31. At this time, due to the relative displacement between the pressing part 52 and the fastening part 11, the bending part 51, the pressing part 52, and the first inflection point 53a to the third inflection point 53c of the flow path cover 5 deform in the direction approaching the heat dissipation fins 32.

[0046] According to the second embodiment described above, the following effects are obtained.

[0047] (2) The fin base 31 has a fastening portion that is fastened to the flow path cover 5 on its outer periphery, thereby applying a fastening force in the vertical arrangement direction of the plurality of heat dissipation fins 32. Therefore, since the bending portion 51, pressing portion 52, and first inflection point 53a to third inflection point 53c of the flow path cover 5 deform in the direction close to the heat dissipation fins 32, the cross-sectional area of ​​the bypass portion 96 can be reduced. Thus, similar to the first embodiment, the heat dissipation performance of the cooling structure of the power conversion device 1A can be improved.

[0048] Third Implementation Method

[0049] Reference Figure 6 The third embodiment of the cooling structure will be described below. In the following description, the same reference numerals are used to denote the same components as in the first embodiment, and the main differences are explained. Points not specifically described are the same as in the first embodiment. The main difference between this embodiment and the first embodiment is that the flow path cover 5 has a multi-stage structure.

[0050] Figure 6 This is a diagram showing the cooling structure of the power conversion device 1B in the third embodiment. Figure 6 Compared with the first embodiment Figure 3 Correspondingly, in this embodiment, the flow path cover 5 has a first flat portion 56, a second flat portion 57, a first inclined portion 58a, and a second inclined portion 58b between the curved portion 51 and the pressing portion 52. The first flat portion 56 and the second flat portion 57 are located at a certain distance from the front end of the heat dissipation fins 32. The first inclined portion 58a and the second inclined portion 58b are located inclined towards the front end of the heat dissipation fins 32.

[0051] In other words, the flow path cover 5 in this embodiment has a multi-stage structure, which approaches the front end of the heat dissipation fins 32 in multiple stages. The first inflection point 53a to the third inflection point 53c exist at points where the cross-section of the flow path cover 5, viewed from a section orthogonal to the refrigerant flow direction, switches between an upward and downward convex shape. The first inflection point 53a is located between the first inclined portion 58a and the second flat portion 57. The second inflection point 53b is located between the second flat portion 57 and the second inclined portion 58b. The third inflection point 53c is located between the second inclined portion 58b and the pressing portion 52.

[0052] According to the third embodiment described above, the following effects are obtained.

[0053] (3) The flow path cover 5 has a multi-stage structure between the curved portion 51 and the pressing portion 52, and this multi-stage structure approaches the front end of the heat dissipation fins 32 in multiple stages. Therefore, the cross-sectional area of ​​the bypass portion 96 can be reduced, and the heat dissipation performance of the cooling structure of the power conversion device 1B can be improved.

[0054] Fourth Implementation Method

[0055] Reference Figure 7 The fourth embodiment of the cooling structure will be described below. In the following description, the same reference numerals are used for the same components as in the first embodiment, and the main differences are explained. Points not specifically described are the same as in the first embodiment. The main difference from the first embodiment in this embodiment is that the flow path cover 5 has a recessed portion.

[0056] Figure 7 This is a diagram showing the cooling structure of the power conversion device 1C in the fourth embodiment. Figure 7 Compared with the first embodiment Figure 3 Correspondingly, in this embodiment, the flow path cover 5 has a recess 59 between the bend 51 and the inflection point. The radius of curvature of the recess 59 is smaller than that of the bend 51, and the recess 59 protrudes in the opposite direction to the bend 51. The recess 59 can be formed, for example, by stamping or the like, from the outside of the flow path cover 5.

[0057] According to the fourth embodiment described above, the following effects are obtained.

[0058] (4) The flow path cover 5 has a recess 59 at a position different from the bending portion 51 and the pressing portion 52. The radius of curvature of the recess 59 is less than a predetermined value, and the recess 59 protrudes in the opposite direction to the bending portion. Therefore, the cross-sectional area of ​​the bypass portion 96 can be further reduced, and the heat dissipation performance of the cooling structure of the power conversion device 1C can be further improved.

[0059] This invention is not limited to the embodiments described above. Other embodiments conceivable within the scope of the technical concept of this invention are also included within the scope of this invention, provided they do not impair the characteristics of the invention. Furthermore, a construction combining the above embodiments and multiple variations can be employed. Moreover, this invention can be applied not only to electric vehicles or hybrid vehicles, but also to power conversion devices for mobile vehicles such as railway vehicles, aircraft, and ships.

[0060] Explanation of reference numerals in the attached figures

[0061] 1. Power conversion devices, 1A, 1B, 1C

[0062] 3 Heat dissipation components

[0063] 4 Framework

[0064] 5. Flow path cover

[0065] 7. Heat conduction components

[0066] 11 Fastening parts

[0067] 31 Fin base

[0068] 32 Heat dissipation fins

[0069] 41 Opening

[0070] 51. Bend

[0071] 52 Pressing Part

[0072] 53a First Inflection Point

[0073] 53b Second Inflection Point

[0074] 53c Third Inflection Point

[0075] 56 First flat section

[0076] 57 Second flat section

[0077] 58a First Inclined Section

[0078] 58b Second Inclined Section

[0079] 59. Depression

[0080] 90 Refrigerant Flow Path

[0081] 96. Bypass section.

Claims

1. A cooling structure forming a refrigerant flow path for allowing refrigerant to circulate internally, the cooling structure comprising: The fin base is thermally connected to the component being cooled and has multiple heat dissipation fins; A frame having an opening that is liquid-tightly sealed by the fin base, and holding the fin base in a manner that allows for relative displacement along the vertical orientation of the plurality of heat dissipation fins; as well as A flow path cover covers the fin base and is liquid-tightly bonded to the frame on the outer periphery of the fin base. The flow path cover has a curved portion with a radius of curvature of more than a predetermined value at a position opposite to the front end of the outermost heat dissipation fin among the plurality of heat dissipation fins. The flow path cover has a pressing portion that is recessed towards the fin base side compared to the apex of the curved portion and abuts against the front end of a portion of the plurality of heat dissipation fins. In a cross section orthogonal to the flow direction of the refrigerant, the flow path cover has multiple inflection points between the curved portion and the pressing portion.

2. The cooling structure according to claim 1, The fin base has a fastening portion that is fastened to the flow path cover on its outer periphery, thereby applying a fastening force in the vertical arrangement direction of the plurality of heat dissipation fins.

3. The cooling structure according to claim 1, The flow path cover has a multi-level structure between the curved portion and the pressing portion, and the multi-level structure approaches the front end of the heat dissipation fins in multiple stages.

4. The cooling structure according to claim 1, The flow path cover has a recessed portion at a position different from the curved portion and the pressing portion, the radius of curvature of the recessed portion is smaller than the predetermined value, and the recessed portion protrudes in the opposite direction to the curved portion.

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