Circuit device

Abstract

The circuit device of the present invention comprises: a first electrical component; a first housing housing the first electrical component and having a cooling flow path for cooling the first electrical component and a discharge port thereon; a second housing housing a second electrical component and having a communicating flow path communicating with the discharge port of the cooling flow path; a first sealing portion disposed at the periphery of the discharge port of the cooling flow path and sealing the first housing and the first electrical component; a second sealing portion disposed at the discharge port of the cooling flow path relative to the first sealing portion and sealing the first housing and the first electrical component; a through hole disposed between the first sealing portion and the second sealing portion of the first housing and penetrating the first housing from the side of the first electrical component to the side of the second housing; and a wall disposed around the discharge port of the cooling flow path in one of the first housing and the second housing, the through hole being disposed outside the wall.

Description

Technical Field

[0001] This invention relates to circuit devices. Background Technology

[0002] Circuit devices that perform power conversion using power semiconductor modules with power switching elements are widely used in civilian applications, vehicle applications, railway applications, and power transmission equipment due to their high conversion efficiency.

[0003] In such a circuit device with a power semiconductor module, there is a cooling flow path for cooling the heat generated from the power semiconductor module. However, there is a concern that cooling water may leak from the cooling flow path and corrode the electrical components inside the circuit device. Therefore, a structure must be designed to prevent cooling water leakage.

[0004] As an example of such a circuit device, some designs incorporate a double-layer sealing structure to prevent corrosion of parts that would corrode if cooled by water. In this structure, a lower cover housing electrical components and a cooling flow path for cooling the electrical components is connected to an upper cover housing a circuit board via a connecting member inserted into a through-hole in both covers. The two covers are assembled in such a way that they are watertight by means of a first sealing member located at the periphery of the lower cover. Furthermore, a second sealing member is provided at the periphery of the through-hole in the lower cover, and a drain groove is provided at the periphery of the upper surface of the lower cover to drain the cooling water that has seeped between the two covers (see, for example, Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-59602 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In the circuit device described in Patent Document 1, the upper and lower covers are assembled in a watertight manner by means of a first sealing member provided on the periphery of the covers. However, the lower cover, which houses the electrical components and cooling channels, has a large space inside. Therefore, when the cooling channels are damaged, it is impossible to prevent cooling water from leaking out of the cooling channels, thus failing to protect the electrical components and connecting members.

[0010] Technical means to solve the problem

[0011] One aspect of the circuit device of the present invention includes: a first electrical component; a first housing housing the first electrical component, having a cooling flow path for cooling the first electrical component and an outlet of the cooling flow path; a second housing housing a second electrical component, having a communicating flow path communicating with the outlet of the cooling flow path; a first sealing portion disposed at the periphery of the outlet of the cooling flow path, sealing the first housing and the first electrical component; a second sealing portion disposed at the outlet of the cooling flow path relative to the first sealing portion, sealing the first housing and the first electrical component; a through hole disposed between the first sealing portion and the second sealing portion of the first housing, penetrating the first housing from the side of the first electrical component to the side of the second housing; and a wall disposed around the outlet of the cooling flow path in one of the first housing and the second housing, the through hole being disposed outside the wall.

[0012] The effects of the invention

[0013] According to the present invention, it is possible to prevent coolant leaking from the outlet of the cooling flow path into the interior of the first housing. Attached Figure Description

[0014] Figure 1 This is a perspective view of one embodiment of the circuit device of the present invention.

[0015] Figure 2 (A) is Figure 1 The diagram shows an exploded perspective view of the circuit device. Figure 2 (B) is Figure 2 An enlarged view of the sealing part shown in (A).

[0016] Figure 3 To view from below Figure 2 A perspective view of the inverter housing of the circuit device illustrated in (A).

[0017] Figure 4 for Figure 3 The circuit device shown in the figure has a cross-sectional view along line IV-IV.

[0018] Figure 5 for Figure 3 The diagram shows a cross-sectional view of the VV line of the circuit device.

[0019] Figure 6 To observe from above Figure 2 The diagram in (A) is a top view of area VI of the circuit device, with the first sealing section, the second sealing section, and the coolant outlet of the power semiconductor module indicated by dashed lines. Detailed Implementation

[0020] 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 omissions and simplifications have been made as appropriate to make the description clearer. The present invention can be implemented in various other forms. Unless otherwise specified, the constituent elements may be singular or plural.

[0021] Regarding the positions, sizes, shapes, and extents of the constituent elements shown in the accompanying drawings, for ease of understanding of the invention, they may not always represent actual positions, sizes, shapes, or extents. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and extents disclosed in the accompanying drawings.

[0022] Figure 1 This is a perspective view of one embodiment of the circuit device of the present invention. Figure 2 (A) is Figure 1 The diagram shows an exploded perspective view of the circuit device. Figure 2 (B) is Figure 2 An enlarged view of the sealing part shown in (A).

[0023] Furthermore, in the following description, the X, Y, and Z directions are as shown in the figure.

[0024] picture Figure 1 As shown in the diagram, the circuit device 100 has an inverter housing 110 and a motor housing 120.

[0025] The inverter housing 110 has the following box-like structure: it has a housing section that houses the power semiconductor module 130 and the power conversion circuit section (not shown), and has an opening on the lower side (-Z direction side).

[0026] The motor housing 120 is a housing that internally houses the motor (not shown). However... Figure 1 , Figure 2 Only a portion of the motor housing 120 is shown in (A).

[0027] The inverter housing 110 and the motor housing 120 are formed by casting metals such as aluminum or iron.

[0028] An inflow pipe 11 for supplying coolant such as cooling water is installed on one side of the inverter housing 110 in the -X direction. An inflow path 111 for supplying coolant is formed on the upper side (Z direction side) of the inverter housing 110 (see reference). Figure 2(A) A flow outlet 111a is provided at one end of the flow path 111. Coolant flows from the inlet pipe 11 into the flow path 111 of the inverter housing 110, and from the flow outlet 111a into the housing of the inverter housing 110, which houses the power semiconductor module 130 and other electrical components. The upper part (Z-direction side) of the flow path 111 is covered by a water channel cover 12. The water channel cover 12 is fixed to the inverter housing 110 by fastening members such as bolts (not shown).

[0029] The power semiconductor module 130 has a flow path forming body 131 with flow paths for cooling power semiconductor elements (not shown). The flow path forming body 131 has a coolant inlet 131a and a coolant outlet 131b. Coolant flowing out from the inlet-side outlet 111a of the inverter housing 110 flows into the flow path forming body 131 through the coolant inlet 131a, cools the internal power semiconductor elements, and is discharged from the coolant outlet 131b.

[0030] A cooling outlet 112 is formed on the upper side (Z direction side) of the inverter housing 110, adjacent to the inflow side flow path 111. The cooling outlet 112 is covered by the motor housing 120.

[0031] The motor housing 120 has a connecting flow path 121 that communicates with the cooling flow path outlet 112 of the inverter housing 110. Coolant flowing out of the cooling flow path outlet 112 of the inverter housing 110 flows into the motor housing 120 through the connecting flow path 121 to cool the motor (not shown) housed inside.

[0032] coolant according to Figure 2 The sequential flow of arrows R1 to R8 in diagram (A).

[0033] picture Figure 2 (A) Figure 2 As shown in (B), a first sealing part 301 and a second sealing part 302 are provided on the periphery of the coolant inlet 131a and coolant outlet 131b of the power semiconductor module 130, respectively.

[0034] Furthermore, a wall 320 is formed around the cooling flow outlet 112 of the inverter housing 110. The wall 320 is integrally formed onto the inverter housing 110 by molding. Although Figure 2 (A) is not illustrated, but a through hole 311 is formed at the periphery of the inflow-side outlet 111a and on the outside of the wall 320, penetrating the upper part of the inverter housing 110 in the vertical direction (Z direction) (see reference). Figure 4 , Figure 5In this embodiment, the power semiconductor module 130 and the inverter housing 110 are sealed in a watertight manner by means of the first sealing part 301 and the second sealing part 302, and the inverter housing 110 and the motor housing 120 are kept watertight by means of the wall 320. These watertight structures will be described below.

[0035] Figure 3 To view from below Figure 2 A perspective view of the inverter housing of the circuit device illustrated in (A).

[0036] exist Figure 3 The bottom (Z-direction side) of the inverter housing 110 in the middle. Figure 2 The upper part of (A) is provided with an inflow-side outlet 111a and a cooling flow path outlet 112. The inflow-side outlet 111a and the cooling flow path outlet 112 of the inverter housing 110 are respectively located opposite to the coolant inlet 131a and coolant outlet 131b of the power semiconductor module 130. Furthermore, Figure 3 The power semiconductor module 130 is illustrated with a double-dotted line.

[0037] Figure 4 for Figure 3 The diagram shows a cross-sectional view of the circuit device along line IV-IV. Figure 5 for Figure 3 The diagram shows a cross-sectional view of the VV line of the circuit device.

[0038] picture Figure 3 , Figure 4 As shown in the figure, an annular first sealing portion 301 and a second sealing portion 302 are provided around the inflow-side outlet 111a of the inverter housing 110. The first sealing portion 301 is provided around the inflow-side outlet 111a, and the second sealing portion 302 is provided around the first sealing portion 301 on the outside of the first sealing portion 301.

[0039] The first sealing part 301 and the second sealing part 302 are formed, for example, by gaskets, and are formed into a ring by a pair of semi-circular arc parts and a pair of straight parts that connect the opposing ends of the semi-circular arc parts to each other.

[0040] On the Y-direction side of the inflow outlet 111a, a through hole 311 is provided between the first sealing part 301 and the second sealing part 302, penetrating the bottom of the inverter housing 110 in the vertical direction (Z-direction). The through hole 311 is located within the enclosed space between the first sealing part 301 and the second sealing part 302, and has no opening to the outside. The first sealing part 301 and the second sealing part 302 are pressed into a groove 133 provided on the inverter housing 110 (see reference). Figure 4 It is fixed within.

[0041] picture Figure 3 , Figure 5 As shown in the diagram, a first sealing portion 301 and a second sealing portion 302 are provided around the cooling flow path outlet 112 of the inverter housing 110. The first sealing portion 301 is provided around the cooling flow path outlet 112, and the second sealing portion 302 is provided around the first sealing portion 301 on its outer side. The first sealing portion 301 and the second sealing portion 302 are formed, for example, by gaskets, and are formed into annular shapes by a pair of semi-circular portions and a pair of straight portions connecting the opposing ends of the semi-circular portions to each other.

[0042] On the -Y direction side of the cooling flow path outlet 112, a through hole 311 is provided between the first sealing part 301 and the second sealing part 302, penetrating the bottom of the inverter housing 110 in the vertical direction (Z direction). The through hole 311 is located within the enclosed space between the first sealing part 301 and the second sealing part 302, and has no opening to the outside. The first sealing part 301 and the second sealing part 302 are pressed into a groove 133 provided on the inverter housing 110 (see reference). Figure 5 It is fixed within.

[0043] picture Figure 5 As shown in the diagram, a wall 320 protruding in the Z direction is formed on the surface of the inverter housing 110 facing the motor housing 120. A sheet-like sealing layer 41 is sandwiched between the wall 320 and the motor housing 120. The sealing layer 41 is not provided in the portion facing the through hole 311 and in the portion where the cooling flow path outlet 112 communicates with the coolant outlet 131b. The sealing layer 41 is formed, for example, by printing or coating a sealing material, or by bonding a sheet-like sealing tape.

[0044] Figure 6 To observe from above Figure 2 The diagram in (A) is a top view of area VI of the circuit device, with the first sealing part 301, the second sealing part 302 and the coolant outlet 131b of the power semiconductor module 130 indicated by dashed lines.

[0045] The wall 320 formed on the inverter housing 110 has an inner annular portion 321, an outer arc portion 322, and a connecting portion 323. The inner annular portion 321 surrounds the cooling flow path outlet 112, the outer arc portion 322 is disposed on the outer periphery of the inner annular portion 321, and the connecting portion 323 connects the inner annular portion 321 and the outer arc portion 322.

[0046] The inner annular portion 321 and the outer arc portion 322 are concentric circles with the cooling flow outlet 112. The outer arc portion 322 is formed as an arc with a length of approximately semicircle along the outer periphery of the inner annular portion 321. A through hole 311 provided on the inverter housing 110 is located between the inner annular portion 321 and the outer arc portion 322 near the connecting portion 323.

[0047] The through-hole 311 of the inverter housing 110 is disposed between the first sealing portion 301 and the second sealing portion 302. The first sealing portion 301 is disposed around the coolant outlet 131b of the power semiconductor module 130. The center of the coolant outlet 131b of the power semiconductor module 130 in the X and Y directions is approximately coaxial with the center O of the cooling flow path outlet 112.

[0048] In the outer arc portion 322, the top end portion 322a on the side opposite to the connecting portion 323 is separated from the inner annular portion 321. The separation between the top end portion 322a of the outer arc portion 322 and the inner annular portion 321 becomes a through hole 311 that connects to the outside opening 335.

[0049] In other words, the through hole 311 is disposed within the leakage restricting area 330, which is surrounded by an inner annular portion 321, an outer arc portion 322, and a connecting portion 323, and is opened to the outside by the top end portion 322a of the outer arc portion 322 and the opening 335 that separates the inner annular portion 321.

[0050] When the coolant flows through the coolant outlet 131b of the power semiconductor module 130 and the coolant flow path outlet 112 of the inverter housing 110, the coolant leaking from the first seal 301 flows through the through hole 311 and out into the leakage limiting area 330 of the inverter housing 110. Because a second seal 302 is provided on the outer periphery of the first seal 301, the coolant flowing into the leakage limiting area 330 will not cross the second seal 302 and spread into the interior of the inverter housing 110. Because a connecting portion 323 of the wall 320 is provided near the through hole 311, the coolant flowing out from the through hole 311 moves towards the opening 335 between the inner annular portion 321 and the outer arc portion 322. Therefore, the situation where coolant seeps into the interior of the inverter housing 110 from the gap between the power semiconductor module 130 and the inverter housing 110 is suppressed. This prevents coolant from adhering to the electronic components housed inside the inverter housing 110.

[0051] Furthermore, by visually confirming that coolant flows from the through-hole 311 through the leakage restriction area 330 to the outer surface 110a of the inverter housing 110, it is possible to detect that coolant has leaked out from the coolant flow path past the first seal 301. This detection allows for appropriate measures, such as repairing the leaking portion of the coolant flow path, before the coolant crosses the second seal 302.

[0052] picture Figure 6 As shown in the diagram, the central angle θ at the center O of the cooling flow path outlet 112, relative to the central angle θ of the straight line L2 passing through the top end 322a of the outer arc portion 322 and the center O of the cooling flow path outlet 112, is set to 90 degrees to 180 degrees, while the central angle θ is relative to the straight line L1 passing through the center of the through hole 311 and the center O of the cooling flow path outlet 112. There is a concern that water or foreign matter may enter the through hole 311 from the opening 335 of the leakage restricting area 330. In this embodiment, the leakage restricting area 330 has an arc shape, so if the central angle θ is 90 degrees or more, water or foreign matter will temporarily move in the opposite direction to the through hole 311, making it less likely for them to enter the through hole 311. Therefore, clogging of the through hole 311 and the infiltration of water or foreign matter into the inverter housing through the through hole 311 can be suppressed.

[0053] Furthermore, if the circuit device 100 suddenly cools down, the air inside the inverter housing 110 will undergo thermal contraction, potentially drawing in water or foreign objects through the through-hole 311. For example, suppose the circuit device 100 is wetted and suddenly cools to room temperature of around 20°C. As a result, the air inside the inverter housing 110 will undergo thermal contraction, leading to the problem of water or foreign objects being drawn in through the through-hole 311. To address this problem, in this embodiment, the volume of the leakage restriction area 330—in other words, the volume of the space within the space sandwiched between the outer surface 110a of the inverter housing 110 and the motor housing 120, and sealed by the inner annular portion 321 and the outer arcuate portion 322 of the wall 320—is made larger than the volume of the air inside the inverter housing 110 that would undergo thermal contraction due to temperature changes.

[0054] Because of this structure, even if the circuit device 100 suddenly cools down and the air inside the inverter housing 110 undergoes thermal contraction, there is no situation where all the air in the leakage limiting circuit area 330 is drawn in through the through hole 311. Therefore, water or foreign matter outside the leakage limiting circuit area 330 will not be drawn in through the through hole 311, thereby preventing the through hole 311 from becoming blocked and water or foreign matter from entering the inverter housing through the through hole 311.

[0055] According to the above implementation method, the following effects are achieved.

[0056] (1) A circuit device 100 comprising: a power semiconductor module (first electrical component) 130; an inverter housing (first housing) 110 housing the power semiconductor module 130 and having a cooling outlet (cooling outlet) 112 for cooling the power semiconductor module 130; a motor housing (second housing) 120 housing a motor (second electrical component) and having a connecting flow path 121 communicating with the cooling outlet 112; and a first sealing portion 301 disposed at the periphery of the cooling outlet 112 to seal the inverter housing 110 and the power semiconductor module 130. A second sealing portion 302, positioned further outward than the first sealing portion 301, is located at the cooling flow path outlet 112 to seal the inverter housing 110 and the power semiconductor module 130. A through hole 311 is located between the first sealing portion 301 and the second sealing portion 302 of the inverter housing 110, penetrating the inverter housing 110 from the power semiconductor module 130 side to the motor housing 120 side. A wall 320 is located around the cooling flow path outlet 112 and is provided on one of the inverter housing 110 and the motor housing 120, with the through hole 311 located outside the wall 320. Therefore, coolant leaking from the first sealing portion 301 and flowing out through the through hole 311 to the outer surface 110a of the inverter housing 110 is restricted from penetrating into the inverter housing 110 by the second sealing portion 302 located on the outer periphery of the first sealing portion 301. This prevents the electrical components housed inside the inverter housing 110 from being corroded by the coolant.

[0057] (2) A wall 320 is disposed on the inverter housing (first housing) 110, and a sheet-like sealing layer 41 is sandwiched between the wall 320 and the motor housing 120 (second housing). Therefore, the water tightness of the inverter housing 110 and the motor housing 120 can be improved with a simple structure.

[0058] (3) The wall 320 has an inner annular portion 321 surrounding the cooling flow path outlet 112 and an outer arc portion 322 disposed outside the inner annular portion 321. One end of the outer arc portion 322 is connected to the inner annular portion 321. The top end (the other end) 322a of the outer arc portion 322 is separated from the inner annular portion 321. The through hole 311 is disposed between the inner annular portion 321 and the outer arc portion 322 and is connected to the vicinity of one end of the outer arc portion 322 of the inner annular portion 321. The central angle θ at the center of the cooling flow path is 90 degrees or more relative to the straight line L1 passing through the center of the through hole 311 and the center of the cooling flow path. Therefore, water or foreign objects are less likely to enter the through hole 311 through the opening 335 formed by separating the top end 322a of the outer arc portion 322 and the inner annular portion 321, thereby suppressing the blockage of the through hole 311 and preventing water or foreign objects from entering the inverter housing through the through hole 311.

[0059] (4) The volume between the inner annular portion 321 and the outer arcuate portion 322 of the wall 320 surrounding the through hole 311 within the space sandwiched between the inverter housing (first housing) 110 and the motor housing (second housing) 120, in other words, the volume of the leakage limiting area 330 is larger than the volume of air inside the inverter housing 110 due to thermal contraction caused by temperature changes. Therefore, even if the circuit device 100 suddenly cools down and the air inside the inverter housing 110 thermally contracts, there is no situation where all the air in the leakage limiting area 330 is drawn in through the through hole 311. Consequently, water or foreign matter outside the leakage limiting area 330 will not be drawn in through the through hole 311, thereby suppressing the blockage of the through hole 311 and preventing water or foreign matter from entering the inverter housing through the through hole 311.

[0060] Furthermore, in the above embodiment, the first sealing portion 301 and the second sealing portion 302 are exemplified as being pressed into the groove 133 provided on the inverter housing 110. However, the first sealing portion 301 and the second sealing portion 302 can also be pressed into the groove of the power semiconductor module 130 by providing a groove on the power semiconductor module 130. In addition, the first sealing portion 301 and the second sealing portion 302 can also be fixed by other methods such as adhesive instead of pressing.

[0061] In the above embodiment, the wall 320 used to seal the inverter housing 110 and the motor housing 120 in a watertight manner is exemplified as a structure integrally formed on the inverter housing 110. However, the wall 320 may also be integrally formed on the motor housing 120.

[0062] In the above embodiment, the inverter housing 110 and the power semiconductor module 130 are exemplified as a watertight structure using the first sealing part 301 and the second sealing part 302, and the inverter housing 110 and the motor housing 120 are exemplified as a watertight structure using the wall 320. However, it is also possible to reverse this and set the inverter housing 110 and the power semiconductor module 130 as a watertight structure using the wall 320, and the inverter housing 110 and the motor housing 120 as a watertight structure using the first sealing part 301 and the second sealing part 302.

[0063] In the above embodiment, a power semiconductor module 130 is exemplified as an electrical component housed within the inverter housing 110. However, in this invention, the electrical component housed within the inverter housing 110 is not limited to the power semiconductor module 130; for example, it can also be applied to a circuit board unit or other electrical components.

[0064] In the above embodiment, the structure is exemplified as supplying coolant from the inverter housing 110 to the motor housing 120 that houses the motor. However, in this invention, the electrical component supplied with coolant via the inverter housing 110 is not limited to the motor, but can also be applied to other electrical components such as gearboxes or converters.

[0065] As described above, the present invention can be applied to circuit board units or other electrical components instead of the power semiconductor module 130, and can be applied to gearboxes or converters instead of motors. Therefore, the present invention can utilize housings other than the inverter housing 110 that house other electrical components.

[0066] Various modifications have been described above, but the present invention is not limited to these. Other forms conceived within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0067] The following disclosure of the priority-based application is incorporated herein by reference: Japanese Patent Application 2019-223178 (filed on December 10, 2019).

[0068] Symbol Explanation

[0069] 41…Sealing layer

[0070] 100…circuit device

[0071] 110…Inverter housing (first housing)

[0072] 110a…outer surface

[0073] 111…Inflow side flow section

[0074] 112…Cooling path outlet (the outlet of the cooling path)

[0075] 120…Motor housing (second housing)

[0076] 121…Connecting Flow Paths

[0077] 130… Power Semiconductor Module (Electrical Component 1)

[0078] 301…First Sealing Section

[0079] 302…Second Sealing Section

[0080] 311…through hole

[0081] 320…wall

[0082] 321…Inner circumferential part

[0083] 322…Outer arc portion

[0084] 322a…Top part (the other end)

[0085] 330…Leakage Restriction Area

[0086] 335…Open Port

[0087] L1… Straight line

[0088] L2… Straight line

[0089] O…The center of the cooling flow path outlet.

Claims

1. A circuit device, characterized in that, have: First electrical component; The first housing houses the first electrical component and has a cooling flow path for cooling the first electrical component and a discharge port for the cooling flow path; The second housing, which houses the second electrical component, has a connecting flow path that communicates with the outlet of the cooling flow path; The first sealing part is provided at the periphery of the outlet of the cooling flow path to seal the first housing and the first electrical component; The second sealing part is disposed at the outlet of the cooling flow path in a manner that is further outward than the first sealing part, thereby sealing the first housing and the first electrical component; A through hole, disposed between the first sealing portion and the second sealing portion of the first housing, penetrating the first housing from the side of the first electrical component towards the side of the second housing; and A wall, which is disposed around the outlet of the cooling flow path in one of the first and second housings, The through hole is located on the outside of the wall. The wall has: An inner annular portion surrounding the cooling flow path; and The outer arc-shaped portion is located outside the inner annular portion. One end of the outer arcuate portion is connected to the inner annular portion, and the other end of the outer arcuate portion is separated from the inner annular portion. The through hole is located between the inner annular portion and the outer arc portion, and is connected to one end of the outer arc portion of the inner annular portion.

2. The circuit device according to claim 1, characterized in that, The wall is disposed in the first cover. A sheet-like sealing layer is sandwiched between the wall and the second cover.

3. The circuit device according to claim 1, characterized in that, The central angle θ at the center of the cooling flow path, relative to the straight line passing through the other end of the outer arc portion and the center of the cooling flow path, is 90 degrees to 180 degrees, and is relative to the straight line passing through the center of the through hole and the center of the outlet of the cooling flow path.

4. The circuit device according to claim 3, characterized in that, The volume between the inner annular portion and the outer arcuate portion of the wall surrounding the through hole within the space sandwiched between the first and second covers is larger than the volume of air in the first cover due to thermal contraction caused by temperature changes.

5. The circuit device according to any one of claims 1 to 4, characterized in that, The first electrical component is a semiconductor module.

6. The circuit device according to any one of claims 1 to 4, characterized in that, The first enclosure is an inverter enclosure that houses the power conversion circuitry.

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