Circuit structure

Abstract

To provide a circuit configuration body having a novel structure capable of reducing heat generation at a connection part of a heating component quickly.SOLUTION: A circuit configuration body 10 includes: a heating component 12 that generates heat by being energized; an energization member 16 connected with a connection part 14 of the heating component 12; a fastening member 18 for fastening the energization member 16 to the connection part 14; and a thermal capacity increasing component 20 that is thermally in contact with a fastening portion between the energization member 16 and the connection part 14, and that increases thermal capacity of the connection part 14 of the heating component 12.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a circuit assembly having a heat generating component. [Background technology]

[0002] Conventionally, in a circuit configuration including heat generating components such as relays and fuses that generate heat when current is applied, a heat dissipation structure for dissipating heat from the heat generating components may be provided. For example, Patent Document 1 proposes a structure for dissipating heat from a relay by utilizing an intermediate portion of a bus bar that connects a connection portion of a relay housed in a case to a connection terminal of a battery arranged outside the case. Specifically, the structure discloses a structure in which the heat generated by the relay is thermally conducted to the chassis or the housing by contacting the intermediate portion of the bus bar extending outside the case housing the relay with a chassis or a housing housing the entire power supply device via an insulating heat dissipation sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-79093 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the structure of Patent Document 1, a heat dissipation structure is provided in the middle of the bus bar that constitutes the current-carrying part that connects the relay and the battery. Therefore, although it is possible to promote heat dissipation from the relay via the bus bar, there is a concern that it is not possible to quickly reduce heat generated at the connection part of the relay when a large current flows.

[0005] Therefore, a circuit assembly having a novel structure is disclosed that can quickly reduce heat generation at the connection portion of heat-generating components. [Means for solving the problem]

[0006] The circuit assembly of the present disclosure includes a heat generating component that generates heat when current is applied thereto, a current-carrying member connected to a connection portion of the heat generating component, a fastening member for fastening the current-carrying member to the connection portion, and a heat capacity increasing component that is in thermal contact with a fastening portion of the current-carrying member and the connection portion and increases the heat capacity of the connection portion of the heat generating component, the current-carrying member having a fastening portion fastened to the connection portion and a heat transfer portion extending from the fastening portion, and the heat capacity increasing component is superimposed on a surface of the current-carrying member opposite to a contact surface thereof with the connection portion. the heat capacity increasing part is formed by one end of the fastening part of the current-carrying member, and is folded back and overlapped on a surface of the current-carrying member opposite to the contact surface with the connection part, the heat transfer part extends from the other end of the fastening part, the current-carrying member has an external connection part and a crank-shaped bent part, and the heat transfer part and the external connection part are connected by the crank-shaped bent part. It is something. In another aspect of the present disclosure, a circuit structure includes a heat-generating component that generates heat when current is passed through it, a conductive member connected to a connection portion of the heat-generating component, a fastening member fastening the conductive member to the connection portion, and a heat capacity increasing component that is in thermal contact with a fastening portion of the heat-generating member and the connection portion and increases the heat capacity of the connection portion of the heat-generating component, wherein the conductive member has a fastening portion fastened to the connection portion and a heat transfer portion extending from the fastening portion, the heat capacity increasing component is superimposed on a surface of the heat-generating member opposite to a contact surface thereof with the connection portion, and when the heat-generating component is placed on the heat transfer portion, the connection portion of the heat-generating component is located on a side, the fastening portion protrudes upward from the heat transfer portion and has a bolt insertion hole that is long in the vertical direction passing through the contact surface and the heat capacity increasing component, and the fastening portion is fastened to the connection portion by a fastening bolt that passes through the bolt insertion hole. Effect of the Invention

[0007] According to the present disclosure, heat generation at the connection portion of heat-generating components can be quickly reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a circuit assembly according to the first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view showing a state in which a cover member constituting a case is removed from the circuit assembly shown in FIG. [Diagram 3] FIG. 3 is an exploded perspective view of the circuit assembly shown in FIG. [Figure 4] FIG. 4 is a perspective view showing a current-carrying member constituting the circuit assembly shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a perspective view showing a circuit assembly according to the second embodiment, and is an enlarged view of a main part with a cover member constituting a case removed. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a perspective view showing a circuit assembly according to the third embodiment, and is an enlarged view of a main part with a cover member constituting a case removed. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a vertical cross-sectional view showing a circuit assembly according to the fourth embodiment, and corresponds to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Description of the embodiments of the present disclosure> First, embodiments of the present disclosure will be listed and described. The circuit configuration of the present disclosure comprises: (1) A heat generating component that generates heat when electricity is passed through it, a conductive member that connects to a connection portion of the heat generating component, a fastening member that fastens the conductive member to the connection portion, and a heat capacity increasing part that is in thermal contact with the fastening portion of the conductive member and the connection portion and increases the heat capacity of the connection portion of the heat generating component.

[0010] According to the circuit configuration of the present disclosure, a heat capacity increasing part is provided at a fastening part between a connection part, which is a heat generating part of a heat generating component, and a current-carrying member connected to the connection part, and the connection part is in thermal contact with the current-carrying member to increase the heat capacity of the connection part. Therefore, the heat of the connection part transferred to the fastening part between the connection part of the heat generating component and the current-carrying member can be reduced by suppressing the temperature rise due to the heat capacity increasing part that is in thermal contact with the fastening part. As a result, compared to a conventional structure in which a current-carrying member is brought into contact with another member at a part separated from the connection part of the heat generating component to dissipate heat, the heat generated at the connection part of the heat generating component can be quickly reduced by the heat capacity increasing part. The heat generating part includes a part that generates heat when current is applied, such as a relay or a fuse.

[0011] The heat capacity increasing part may be any part that can increase the heat capacity of the connection part of the heat generating part by thermally contacting the connection part and the fastening part of the current-carrying member. For example, a part made of metal such as iron, copper, aluminum, or an alloy of these metals, which have high thermal conductivity, or a part made of synthetic resin may be used. In addition, the shape of the heat capacity increasing part is not particularly limited, and any shape may be used as long as the shape can be thermally contacted with the connection part and the fastening part of the current-carrying member.

[0012] As the fastening member, any known fastening member may be used as long as it can be used for fastening current-carrying members, and bolts, rivets, etc. may be advantageously used.

[0013] (2) It is preferable that the device further includes a heat conductive member and a case, and the current-carrying member is in thermal contact with the case via the heat conductive member. The heat transferred to the current-carrying member can be dissipated from the case through the heat conductive member. Therefore, the heat of the heat-generating component can be reduced. In this embodiment, for example, a sheet-shaped heat conductive member is preferably used.

[0014] (3) It is preferable that the heat capacity increasing part is made of metal and is fastened to the connection part together with the current-carrying member by the fastening member. This is because the heat capacity increasing part is made of metal and is fastened to the connection part together with the current-carrying member, so that the heat capacity of the connection part can be easily and reliably increased. Note that the heat capacity increasing part may be formed integrally with the current-carrying member, or may be a part separate from the current-carrying member.

[0015] (4) It is preferable that the heat capacity increasing part is superimposed on the surface of the current-carrying member opposite to the contact surface with the connection part. Since the heat capacity increasing part is superimposed on the surface of the current-carrying member opposite to the contact surface with the connection part, it is possible to prevent the heat capacity increasing part from being interposed between the current-carrying member and the connection part when the current-carrying member is fastened to the connection part by the fastening member. Therefore, it is possible to increase the heat capacity of the connection part without increasing the conduction resistance.

[0016] (5) It is preferable that the heat capacity increasing part is formed by an end of the current-carrying member, and is folded back and overlapped on the surface of the current-carrying member opposite to the contact surface with the connection part. Since the heat capacity increasing part is formed by the end of the current-carrying member, an increase in the number of parts can be suppressed. Moreover, since the heat capacity increasing part is folded back and overlapped on the surface of the current-carrying member opposite to the contact surface with the connection part, it is possible to prevent the heat capacity increasing part from being interposed between the current-carrying member and the connection part when the current-carrying member is fastened to the connection part by a fastening member. Therefore, it is possible to increase the heat capacity of the connection part without increasing the conduction resistance.

[0017] (6) It is preferable that the current-carrying member is provided with a holding portion for holding the end of the current-carrying member constituting the heat capacity increasing part and the surface of the current-carrying member opposite to the contact surface with the connection part in an overlapping state. The holding portion can keep the gap between the current-carrying member and the heat capacity increasing part (the end of the folded current-carrying member) small, and the current-carrying member and the heat capacity increasing part can be stably contacted with each other with a wide contact area. This can increase the heat capacity of the connection part more reliably.

[0018] (7) It is preferable that the linear expansion coefficient of the heat capacity increasing part is 1 / 3 to 3 times that of the fastening member. Since the heat capacity increasing part has a linear expansion coefficient similar to that of the fastening member, the fastening member is less likely to loosen due to heat generation.

[0019] (8) It is preferable that the heat capacity increasing part and the fastening member are made of the same material. Since the heat capacity increasing part and the fastening member have the same linear expansion coefficient, loosening of the fastening member due to heat generation can be more reliably prevented.

[0020] (9) It is preferable that the heat capacity increasing part is constituted by a cap attached to the fastening member. This is because even a cap attached to a fastening member can increase the heat capacity of the connection part and can quickly reduce heat generation at the connection part of the heat generating component.

[0021] (10) It is preferable that the cap is made of metal. By using a metal cap having high thermal conductivity, it is possible to suppress a temperature rise at the connection portion.

[0022] (11) It is preferable that a heat conductive member is provided between the cap and the fastening member. The heat conductive member can stably transfer heat from the fastening member to the cap. In this aspect, for example, a grease-like heat conductive member is preferably used.

[0023] (12) It is preferable that the cap is made of a synthetic resin. By using a synthetic resin that is softer than metal as the material of the cap, the cap can be attached to the fastening member with almost no gap. Therefore, heat can be stably transferred from the fastening member to the cap, and the heat capacity of the connection part can be increased more reliably.

[0024] <Details of the embodiment of the present disclosure> Specific examples of the circuit configuration of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0025] <Embodiment 1> A first embodiment of the present disclosure will be described below with reference to Figs. 1 to 5. The circuit assembly 10 of the first embodiment is mounted on a vehicle (not shown), such as an electric vehicle or a hybrid vehicle, and supplies and controls electric power from a power source (not shown) such as a battery to a load (not shown) such as a motor. The circuit assembly 10 can be arranged in any orientation, but in the following description, the X direction is the forward direction, the Y direction is the rightward direction, and the Z direction is the upward direction. In addition, for multiple identical members, only some of the members may be labeled with reference numerals, and the reference numerals may be omitted for the other members.

[0026] <Circuit construct 10> The circuit assembly 10 includes a relay 12 as a heat-generating component that generates heat when current is applied, a current-carrying bus bar 16 as a current-carrying member that is connected to a connection portion 14 of the relay 12, and a bolt 18 as a fastening member that fastens the current-carrying bus bar 16 to the connection portion 14 of the relay 12. The circuit assembly 10 also includes a heat capacity increasing component 20 that is in thermal contact with a fastening portion A (an area surrounded by a two-dot chain line in the drawing) between the current-carrying bus bar 16 and the connection portion 14. The circuit assembly 10 further includes a case 22. The relay 12, the current-carrying bus bar 16, the bolt 18, and the heat capacity increasing component 20 are all housed in the case 22. The case 22 also houses a fuse 24 that generates heat when current is applied, and a current sensor 26.

[0027] <Case 22> The case 22 is generally box-shaped and is made of, for example, synthetic resin. In the first embodiment, the case 22 is generally rectangular extending in the left-right direction in a plan view. The case 22 can be divided in the top-bottom direction and is configured to include a base member 28 located at the bottom and a lid member 30 located at the top. The base member 28 is box-shaped and opens upward. The lid member 30 is box-shaped and opens downward. The case 22 is configured by covering the upper opening of the base member 28 with the lid member 30 and fixing the base member 28 and the lid member 30 to each other. The fixing means between the base member 28 and the lid member 30 is not limited, and any fixing means known in the art, such as adhesion, welding, press-fitting, or concave-convex fitting, can be used. The case 22 may be made of metal, and insulation may be ensured by providing an insulating coating on the surface of the case 22.

[0028] The base member 28 includes a substantially rectangular bottom wall 32 extending in the left-right direction, and a peripheral wall 34 protruding upward from the outer periphery of the bottom wall 32. In the first embodiment, a rectangular first accommodating recess 36 opening upward is formed on the upper surface of the bottom wall 32. That is, a step 38 is formed on the upper surface of the bottom wall 32, and the portion surrounded by the step 38 is the first accommodating recess 36. In particular, in the first embodiment, four first accommodating recesses 36 are formed on the upper surface of the bottom wall 32, each having a predetermined size and spaced apart from the other by a predetermined distance in the left-right direction.

[0029] 5, a rectangular second accommodating recess 40 that opens downward is formed in the lower surface of the bottom wall 32 at a position corresponding to the first accommodating recess 36. That is, a step 42 is formed in the lower surface of the bottom wall 32, and the portion surrounded by the step 42 is the second accommodating recess 40. Four second accommodating recesses 40 are provided with sizes and positions corresponding to the first accommodating recess 36. Therefore, in the first embodiment, the bottom wall 32 is thinner at the positions where the first and second accommodating recesses 36, 40 are formed than other portions.

[0030] The cover member 30 includes a generally rectangular upper bottom wall 44 extending in the left-right direction, and a peripheral wall 46 protruding downward from the outer periphery of the upper bottom wall 44. In the first embodiment, rectangular openings 48a, 48b penetrating in the up-down direction are formed at both left-right ends of the upper bottom wall 44. In addition, a plurality of bolt insertion holes 50 penetrating in the up-down direction are formed in the outer periphery of the cover member 30.

[0031] <Relay 12, fuse 24, current sensor 26> The relay 12 includes a relay body 52 having a hollow rectangular parallelepiped shape. A pair of connection parts 14, 14 (a first connection part 14a and a second connection part 14b) are provided on the front surface of the relay body 52, spaced apart from each other in the left-right direction. An insulating plate 54 protruding forward is provided between the first connection part 14a and the second connection part 14b.

[0032] Furthermore, a plurality of legs 56 that protrude outward in the left-right direction are provided on the relay body 52. ​​These legs 56 are formed with bolt insertion holes that penetrate in the up-down direction.

[0033] The fuse 24 has a fuse body 60 having a substantially rectangular parallelepiped shape. The fuse body 60 is provided with metal connection parts 62, 62 that protrude on both the left and right sides. These connection parts 62, 62 have bolt insertion holes that penetrate in the vertical direction.

[0034] The current sensor 26 includes a sensor body 66 having a substantially rectangular parallelepiped shape. Metallic connection parts 68, 68 protruding on both the left and right sides are provided on the sensor body 66. These connection parts 68, 68 have bolt insertion holes formed therein that penetrate in the vertical direction.

[0035] <Electric busbar 16> The current-carrying busbar 16 is formed by bending a metal plate into a predetermined shape by pressing or the like. The material of the current-carrying busbar 16 is not limited, but copper, copper alloy, aluminum, aluminum alloy, etc. are preferably used. The linear expansion coefficient of copper is about 16 to 17(×10 -6 / K). The linear expansion coefficient of aluminum is about 23 to 24 (×10 -6 / K) In the first embodiment, as shown in Fig. 4, a pair of current-carrying bus bars 16, 16 (a first current-carrying bus bar 16a and a second current-carrying bus bar 16b) are provided spaced apart from each other in the left-right direction.

[0036] The first current busbar 16a extends in the left-right direction as a whole. The right end of the first current busbar 16a is provided with a rectangular bolt fastening portion 72 that extends in the up-down direction (YZ plane). A rectangular heat transfer portion 74 that extends in the horizontal direction (XY plane) extends rearward from the lower end of the bolt fastening portion 72. The left end of the first current busbar 16a is provided with a rectangular external connection portion 76 that extends in the horizontal direction (XY plane). The heat transfer portion 74 and the external connection portion 76 are connected to each other by a portion that is bent in a crank shape at the middle part in the left-right direction.

[0037] Furthermore, an upper end of the bolt fastening portion 72 of the first current-carrying busbar 16a is folded back forward and overlapped with a lower end portion of the bolt fastening portion 72. The upper end of the bolt fastening portion 72 before being folded back is indicated by a two-dot chain line in FIG. 4. This folded back and overlapped portion is the heat capacity increasing part 20. That is, in the first embodiment, the heat capacity increasing part 20 is made of metal and is the same material as the current-carrying busbar 16 (the first and second current-carrying busbars 16a, 16b). The first current-carrying busbar 16a is formed with a thickness dimension equivalent to two sheets at the formation position of the heat capacity increasing part 20. The rear surface of the bolt fastening part 72 is a contact surface 78 that contacts the first connection part 14a of the relay 12. Therefore, the upper end of the bolt fastening part 72 (the heat capacity increasing part 20), which is the end of the first current-carrying busbar 16a, is overlapped with a front surface 79, which is the surface of the bolt fastening part 72 opposite to the contact surface 78.

[0038] Furthermore, the first current-carrying bus bar 16a is provided with a holding portion 80 that maintains the overlapping state between the heat capacity increasing part 20 and the front surface 79 of the bolt fastening part 72. The shape of the holding portion 80 is not limited, but in the first embodiment, the holding portion 80 is a metal member that is integrally formed with the first current-carrying bus bar 16a. Specifically, a pair of band-shaped holding portions 80, 80 are provided on both the left and right sides of the bolt fastening part 72. Then, with the heat capacity increasing part 20 (the upper end part of the bolt fastening part 72) overlapped on the front surface 79 of the bolt fastening part 72, the holding portions 80, 80 are bent and crimped to maintain the overlapping state of the heat capacity increasing part 20 (the upper end part of the bolt fastening part 72).

[0039] Further, the bolt fastening portion 72 is formed with a bolt insertion hole 82 penetrating in the front-rear direction. In the first embodiment, the bolt insertion hole 82 is formed in a portion where the heat capacity increasing component 20 is provided (a portion where the upper end portion of the bolt fastening portion 72 is folded back and overlapped). Therefore, the bolt insertion hole 82 is formed penetrating in the front-rear direction through a portion having a thickness dimension equivalent to two sheets of the first current-carrying bus bar 16a. Note that the bolt insertion hole 82 may be formed by forming a through hole in each of the upper end portion and the lower end portion of the bolt fastening portion 72 before the upper end portion of the bolt fastening portion 72 is folded back, and folding back the upper end portion of the bolt fastening portion 72 to connect both the through holes. Alternatively, the bolt insertion hole 82 may be formed in a portion having a thickness dimension equivalent to two sheets after the upper end portion of the bolt fastening portion 72 is folded back and overlapped. The first current-carrying bus bar 16a including the heat capacity increasing component 20 is fixed by inserting the bolt 18 into the bolt insertion hole 82 and fastening it to the first connection portion 14a. In other words, by fastening the bolt 18, not only the first current-carrying bus bar having the thickness dimension of one sheet, but also the heat capacity increasing component 20 having the thickness dimension of another sheet are fixed to the first connection portion 14a.

[0040] Furthermore, in the first embodiment, the bolt insertion hole 82 has an elliptical shape that is long in the vertical direction. This makes it possible to adjust the vertical position of the first current-carrying bus bar 16a with respect to the relay 12 when fastening the relay 12 and the first current-carrying bus bar 16a, which will be described later. As a result, as will be described later, the heat transfer portion 74 can be brought into more reliable thermal contact with the case 22 (or the thermally conductive sheet 114, which will be described later). Furthermore, the external connection portion 76 is formed with a bolt insertion hole 84 that penetrates in the thickness direction (vertical direction).

[0041] The second energized busbar 16b has a shape that is substantially symmetrical to the first energized busbar 16a in the left-right direction. That is, a bolt fastening portion 72 is provided in the front of the left end portion of the second energized busbar 16b. A heat transfer portion 74 extends rearward from the lower end portion of the bolt fastening portion 72. A rectangular fuse connection portion 86 that spreads in the horizontal direction (XY plane) is provided in the right end portion of the second energized busbar 16b. The heat transfer portion 74 and the fuse connection portion 86 are connected by a portion that is bent in a crank shape in the middle portion in the left-right direction. Furthermore, a bolt insertion hole 88 that penetrates in the thickness direction (up-down direction) is formed in the fuse connection portion 86.

[0042] The upper end of the bolt fastening portion 72 of the second energized busbar 16b is folded forward to form the heat capacity increasing component 20. The heat capacity increasing component 20 (the upper end of the bolt fastening portion 72) is folded back and held in a state overlapping with the front surface 79 by the holding portions 80, 80. Furthermore, in a state in which the heat capacity increasing component 20 is provided, the bolt fastening portion 72 is formed with a bolt insertion hole 82 penetrating in the thickness direction (front-rear direction). The second energized busbar 16b including the heat capacity increasing component 20 is fixed by inserting the bolt 18 into the bolt insertion hole 82 and fastening it to the second connecting portion 14b. That is, by fastening the bolt 18, the heat capacity increasing component 20 is fixed to the second connecting portion 14b together with the second energized busbar 16b.

[0043] <Third current-carrying bus bar 90, fourth current-carrying bus bar 92> 2 and 3, a third energized bus bar 90 is connected to the fuse 24 and the current sensor 26. A fourth energized bus bar 92 is connected to the side of the current sensor 26 opposite to the side to which the third energized bus bar 90 is connected. Similar to the first and second energized bus bars 16a, 16b, these third and fourth energized bus bars 90, 92 are also formed by bending a metal plate into a predetermined shape by pressing or the like.

[0044] The third energized bus bar 90 is provided with a horizontally extending rectangular fuse connection portion 94 and a sensor connection portion 96 at both left and right ends. That is, the third energized bus bar 90 is provided with the fuse connection portion 94 on the left and the sensor connection portion 96 on the right. The fuse connection portion 94 and the sensor connection portion 96 are provided with bolt insertion holes penetrating in the thickness direction (vertical direction).

[0045] In the first embodiment, the third current-carrying bus bar 90 has a generally gutter-shaped portion that extends in the front-rear direction and opens upward. A fuse connection portion 94 and a sensor connection portion 96 extend outward in the left-right direction from both left and right end portions of the upper opening of this generally gutter-shaped portion. The bottom wall of the generally gutter-shaped portion is a heat transfer portion 102 that is in thermal contact with the case 22 (base member 28) when the circuit assembly 10 is assembled.

[0046] The fourth energized bus bar 92 has a structure similar to that of the third energized bus bar 90. That is, the fourth energized bus bar 92 has a generally gutter-shaped portion that extends in the front-rear direction and opens upward. A sensor connection portion 104 extends leftward from a left end portion of the upper opening of the generally gutter-shaped portion, and an external connection portion 106 extends rightward from a right end portion. A bolt insertion hole penetrating in the thickness direction (vertical direction) is formed in the sensor connection portion 104. In addition, a bolt insertion hole penetrating in the thickness direction (vertical direction) is formed in the external connection portion 106. The bottom wall of the generally gutter-shaped portion is a heat transfer portion 112 that is in thermal contact with the case 22 (base member 28) when the circuit assembly 10 is assembled.

[0047] <Bolt 18> The relay 12 and the first and second current-carrying bus bars 16a, 16b are fixed by bolts 18, 18. Specifically, the first and second connection portions 14a, 14b are aligned with the bolt insertion holes 82, 82 of the bolt fastening portions 72, 72, and the bolts 18, 18 are inserted and fastened. The bolts 18 may be made of a well-known material such as iron or stainless steel. In the first embodiment, the bolts 18 are made of iron. The linear expansion coefficient of iron is approximately 11 to 12 (×10 -6 / K).

[0048] <Thermal conductive sheets 114, 116> When the circuit configuration 10 is assembled, the heat transfer portions 74, 74, 102, 112 of the first to fourth current-carrying bus bars 16a, 16b, 90, 92 are in thermal contact with the case 22 (base member 28). In the first embodiment, a heat conduction sheet 114 is accommodated in each of the first accommodating recesses 36 of the base member 28 as a heat conduction member. Each of the heat transfer portions 74, 74, 102, 112 is in thermal contact with the base member 28 via the heat conduction sheet 114.

[0049] In the first embodiment, a thermally conductive sheet 116 is also housed in each of the second accommodating recesses 40 of the base member 28. When the circuit assembly 10 is mounted on a vehicle, the base member 28 is in thermal contact with a heat sink 118 such as a vehicle body panel or a housing, via each of the thermally conductive sheets 116.

[0050] The thermally conductive sheets 114 and 116 are flat sheets in the vertical direction and made of synthetic resin with a higher thermal conductivity than air. Specifically, silicone resin, non-silicone acrylic resin, ceramic resin, etc. can be used. More specifically, thermally conductive silicone rubber, etc. can be used. The thermally conductive sheets 114 and 116 have flexibility and elasticity, and can be elastically deformed so that the thickness dimension changes depending on the force applied in the vertical direction. In the first embodiment, the thermally conductive sheets 114 and 116 are respectively used as thermally conductive members provided on both the upper and lower surfaces of the base member 28, but both the thermally conductive members are not limited to this embodiment and any thermally conductive member of any shape can be used. For example, a heat dissipation gap filler or thermally conductive grease made of a silicone resin may be used.

[0051] In particular, in the first embodiment, the thermally conductive sheet 114 is accommodated in the first accommodating recess 36 having the step 38, so that the thermally conductive sheet 114 is positioned relative to the base member 28. Also, the thermally conductive sheet 116 is accommodated in the second accommodating recess 40 having the step 42, so that the thermally conductive sheet 116 is positioned relative to the base member 28. Furthermore, it is preferable that each thermally conductive sheet 114 is sandwiched in a compressed state between each of the heat transfer parts 74, 74, 102, 112 and the base member 28 in the vertical direction. By being compressed, each thermally conductive sheet 114 can be in contact with each of the heat transfer parts 74, 74, 102, 112 and the base member 28 with a high degree of adhesion. This allows each thermally conductive sheet 114 to efficiently transfer heat from the heat transfer parts 74, 74, 102, 112 to the base member 28. Similarly, it is preferable that each thermally conductive sheet 116 is sandwiched in a compressed state between the base member 28 and the heat sink 118 in the vertical direction. By being compressed, the thermally conductive sheet 116 can come into close contact with the base member 28 and the heat sink 118. This allows the thermally conductive sheet 116 to efficiently conduct heat from the base member 28 to the heat sink 118.

[0052] <Assembly process of the circuit structure 10> Next, a specific example of the process of assembling the circuit assembly 10 will be described. Note that the process of assembling the circuit assembly 10 is not limited to the following description.

[0053] First, the cover member 30, the relay 12, the fuse 24, the current sensor 26, the first to fourth energized bus bars 16a, 16b, 90, 92, and the bolt 18 are prepared. Then, the relay 12 is placed on the upper bottom wall 44 of the cover member 30 that has been turned upside down, and the bolts are inserted into the legs 56 and fastened to the bolt fastening parts (not shown) provided on the cover member 30. This fixes the cover member 30 and the relay 12. After that, the first and second energized bus bars 16a, 16b are placed above the relay 12, and the first and second connecting parts 14a, 14b of the relay 12 are aligned with the bolt insertion holes 82, 82 of the first and second energized bus bars 16a, 16b. Next, the bolts 18, 18 are inserted into the first and second connecting parts 14a, 14b and the bolt insertion holes 82, 82 to fasten them. This fixes the relay 12 to the first and second current-carrying bus bars 16a, 16b.

[0054] Next, the third energized bus bar 90 and the fourth energized bus bar 92 are placed on the upper bottom wall 44 of the lid member 30, and the fuse 24 and the current sensor 26 are placed on top of them. As a result, the fuse connection portion 86 of the second energized bus bar 16b is overlapped with the left connection portion 62 of the fuse 24. The right connection portion 62 of the fuse 24 is overlapped with the fuse connection portion 94 of the third energized bus bar 90. The sensor connection portion 96 of the third energized bus bar 90 is overlapped with the left connection portion 68 of the current sensor 26. The right connection portion 68 of the current sensor 26 is overlapped with the sensor connection portion 104 of the fourth energized bus bar 92. Then, bolts are inserted through the overlapped connection portions 62, 68, fuse connection portions 86, 94, and sensor connection portions 96, 104, and are fastened to bolt fixing portions (not shown) provided on the lid member 30. As a result, in addition to the relay 12 and the first and second energized bus bars 16a, 16b, the fuse 24, the current sensor 26, the third energized bus bar 90, and the fourth energized bus bar 92 are fixed to the cover member 30.

[0055] Furthermore, the base member 28 and the thermally conductive sheets 114 and 116 are prepared. Then, the thermally conductive sheet 114 is accommodated in each of the first accommodating recesses 36 of the base member 28 and fixed with an adhesive or the like. Also, the thermally conductive sheet 116 is accommodated in each of the second accommodating recesses 40 and fixed with an adhesive or the like. Thereafter, the upper opening of the lid member 30 to which the relay 12, the fuse 24, the current sensor 26, and the first to fourth current-carrying bus bars 16a, 16b, 90, and 92 are fixed is covered with the base member 28 to which the thermally conductive sheets 114 and 116 are fixed, and the lid member 30 and the base member 28 are fixed to each other to form the case 22. Thereafter, the circuit assembly 10 is completed by turning it upside down.

[0056] The order in which the relay 12, the fuse 24, the current sensor 26, and the first to fourth energized bus bars 16a, 16b, 90, 92 are fixed to the cover member 30 is not limited to the above steps. Furthermore, each of the thermally conductive sheets 114 provided between the first to fourth energized bus bars 16a, 16b, 90, 92 (heat transfer sections 74, 74, 102, 112) and the base member 28 may not be fixed to the base member 28 but may be fixed to the lower surface of each of the heat transfer sections 74, 74, 102, 112. Similarly, each of the thermally conductive sheets 116 provided on the lower surface of the base member 28 may not be fixed to the base member 28 but may be fixed to the heat sink 118.

[0057] In the circuit assembly 10 assembled in this manner, the external connection parts 76, 106 of the first and fourth electric bus bars 16a, 92 are exposed to the outside through the openings 48a, 48b of the cover member 30. Then, the external electric wires are electrically connected to the first and fourth electric bus bars 16a, 92 by inserting and fastening a bolt (not shown) while aligning a terminal part provided at an end of the external electric wire (not shown) with the bolt insertion holes 84, 110 of the external connection parts 76, 106. The circuit assembly 10 and the heat sink 118 are overlapped with each other, and a bolt (not shown) is inserted and fastened through a bolt insertion hole 50 provided in the outer periphery of the case 22 (cover member 30), thereby fixing the circuit assembly 10 to the heat sink 118. As a result, in the first embodiment, the thermally conductive sheet 116 is compressed between the circuit assembly 10 and the heat sink 118 in the up-down direction.

[0058] In the circuit assembly 10 of the first embodiment, the first and second current-carrying busbars 16a, 16b are provided with heat capacity increasing parts 20, 20 that are in thermal contact with the fastening parts A of the first and second connecting parts 14a, 14b of the relay 12. Specifically, the heat capacity increasing parts 20 are configured by folding back and overlapping the upper ends of the bolt fastening parts 72, 72 of the first and second current-carrying busbars 16a, 16b. As a result, at the fastening parts A between the first and second current-carrying busbars 16a, 16b and the first and second connecting parts 14a, 14b of the relay 12, the first and second current-carrying busbars 16a, 16b each have a thickness equivalent to two sheets. Therefore, the heat capacity of the first and second current-carrying busbars 16a, 16b can be increased compared to when the first and second current-carrying busbars are simply made to have a thickness equivalent to one sheet. This makes it possible to suppress the temperature rise of the first and second current bus bars 16a, 16b, and ultimately the first and second connection portions 14a, 14b connected to the first and second current bus bars 16a, 16b, thereby eliminating the problem of heat generation when a large current flows temporarily.

[0059] In the first embodiment, the heat transfer sections 74, 74, 102, 112 of the first to fourth current-carrying bus bars 16a, 16b, 90, 92 are in thermal contact with the case 22 (base member 28), respectively, so that the heat of the relay 12, the fuse 24, and the current sensor 26 generated by energization can be dissipated through the case 22. This can also solve the problem of heat generation by the relay 12, the fuse 24, and the current sensor 26. In particular, in the first embodiment, the heat transfer sheet 114 is provided between the heat transfer sections 74, 74, 102, 112 and the base member 28, so that the heat transfer from the heat transfer sections 74, 74, 102, 112 to the base member 28 is stably realized. Furthermore, a heat transfer sheet 116 is provided on the lower surface of the base member 28, and the base member 28 and the heat sink 118 are in thermal contact with each other via the heat transfer sheet 116. As a result, heat generated by the relay 12, fuse 24, and current sensor 26 is also dissipated from the heat sink 118, improving the heat dissipation effect.

[0060] Furthermore, in the first embodiment, the heat capacity increasing parts 20 are configured by the upper ends of the bolt fastening parts 72 of the first and second current-carrying bus bars 16a and 16b, and the bolt insertion holes 82 are formed in the parts where the heat capacity increasing parts 20 are provided. As a result, the heat capacity increasing parts 20 are fixed together with the first and second current-carrying bus bars 16a and 16b by fastening the bolts 18. That is, in the first embodiment, the first and second current-carrying bus bars 16a and 16b and the heat capacity increasing parts 20 are integrally formed, so that an increase in the number of parts is avoided. Also, assembling workability can be improved compared to a case where the heat capacity increasing parts are separate from the first and second current-carrying bus bars 16a and 16b.

[0061] In particular, in the first embodiment, the upper end portions of the bolt fastening portions 72, 72 are folded back outward (forward) and overlapped. This makes it possible to shorten the electrical path from the first and second connecting portions 14a, 14b to the external connecting portion 76 and the fuse connecting portion 86, compared to the case where the upper end portions of the bolt fastening portions are folded back inward. This makes it possible to avoid an increase in conduction resistance due to current flow. In addition, it is possible to shorten the thermal path from the first and second connecting portions 14a, 14b to the heat transfer portions 74, 74. This allows the heat generated in the first and second connecting portions 14a, 14b to be dissipated more quickly through the heat transfer portions 74, 74.

[0062] Furthermore, the first and second current-carrying bus bars 16a and 16b are provided with holding portions 80 that hold the overlapped state of the heat capacity increasing parts 20 (upper ends of the bolt fastening parts 72). Therefore, no gap is generated between the heat capacity increasing parts 20 and the bolt fastening parts 72, in other words, between the upper and lower ends of the overlapped bolt fastening parts 72, and the heat capacity at the positions where the heat capacity increasing parts 20 are provided can be stably increased.

[0063] The linear expansion coefficient of the heat capacity increasing component 20 (first and second current-carrying bus bars 16a, 16b) is preferably set within a range of 1 / 3 to 3 times that of the bolts 18, 18. The linear expansion coefficient of the heat capacity increasing component 20 (first and second current-carrying bus bars 16a, 16b) is more preferably set within a range of 1 / 2 to 2 times that of the bolts 18, 18. The linear expansion coefficient of the heat capacity increasing component 20 (first and second current-carrying bus bars 16a, 16b) is more preferably set within a range of 2 / 3 to 3 / 2 times that of the bolts 18, 18. The linear expansion coefficient of the heat capacity increasing component 20 (first and second current-carrying bus bars 16a, 16b) is most preferably set equal to that of the bolts 18, 18. By setting the linear expansion coefficient of the heat capacity increasing parts 20 (first and second current-carrying bus bars 16a, 16b) relatively close to that of the bolts 18, at 1 / 3 to 3 times, it is possible to prevent the bolts 18, 18 from loosening when the relay 12 generates heat. Incidentally, for example, if the first and second current-carrying bus bars 16a, 16b are made of copper and the bolts 18, 18 are made of iron, the linear expansion coefficient of the heat capacity increasing parts 20, 20 relative to that of the bolts 18, 18 is approximately 1.4 times.

[0064] In particular, by making the linear expansion coefficients of the heat capacity increasing parts 20 (first and second current-carrying bus bars 16a, 16b) and the bolts 18, 18 equal, i.e., by making the heat capacity increasing parts 20 (first and second current-carrying bus bars 16a, 16b) and the bolts 18, 18 out of the same material, loosening of the bolts 18, 18 when the relay 12 heats up can be further prevented.

[0065] <Embodiment 2> A second embodiment of the present disclosure will be described below with reference to Figs. 6 and 7. The circuit assembly 120 of the second embodiment has a similar basic structure to the circuit assembly 10 of the first embodiment, but differs in that the heat capacity increasing components 122, 122 are separate from the first and second current-carrying bus bars 124a, 124b, which are current-carrying members. In the following description, the same reference numerals as in the first embodiment are used in the drawings to denote substantially the same members and parts as in the first embodiment, and detailed description thereof will be omitted. In Figs. 6 and 7, the circuit assembly 120 is shown with the cover member 30 constituting the case 22 removed.

[0066] The heat capacity increasing part 122 in the second embodiment is a rectangular block. A through hole 126 is formed in the approximate center of the heat capacity increasing part 122, penetrating in the front-rear direction. The material of the heat capacity increasing part 122 is not limited as long as it increases the heat capacity of the first and second current-carrying bus bars 124a, 124b, and therefore the first and second connection parts 14a, 14b when assembled, but is preferably a metal with high thermal conductivity. Iron, copper, aluminum, and alloys thereof are more preferably used as the material of the heat capacity increasing part 122. In the second embodiment, the heat capacity increasing part 122 is formed of a metal. It is desirable that the heat capacity increasing part 122 is formed of a metal with a lower specific gravity than copper or iron. This is because the influence of the vibration of the bolt 18 can be reduced by using a metal with a lower specific gravity.

[0067] The heat capacity increasing part 122 of the second embodiment is fixed to the relay 12 together with the first and second energizing bus bars 124a, 124b by the bolts 18. That is, the first and second connecting parts 14a, 14b of the relay 12, the bolt insertion holes 82 of the first and second energizing bus bars 124a, 124b, and the through holes 126 of the heat capacity increasing part 122 are aligned with each other. Then, the bolts 18 are inserted and fastened, so that the heat capacity increasing parts 122, 122 are fixed to the relay 12 together with the first and second energizing bus bars 124a, 124b. As a result, the heat capacity increasing parts 122, 122 are in thermal contact with the fastening parts A between the first and second energizing bus bars 124a, 124b and the first and second connecting parts 14a, 14b. In particular, also in the second embodiment, the heat capacity increasing component 122 is overlapped on a front surface 79, which is the surface opposite to the contact surface 78 with the first and second connection portions 14a, 14b, of the bolt fastening portions 72 of the first and second current-carrying bus bars 124a, 124b. Note that in the first embodiment, the upper end portions of the bolt fastening portions 72 are folded back so that the fastening portions of the bolts 18 of the first and second current-carrying bus bars 16a, 16b have a thickness dimension equivalent to two sheets, but in the second embodiment, the fastening portions of the bolts 18 of the first and second current-carrying bus bars 124a, 124b have a thickness dimension equivalent to one sheet.

[0068] In the circuit assembly 120 of the second embodiment, the heat capacity increasing component 122 is provided, and thus the heat capacity of the fastening portion A between the first and second connection portions 14a, 14b of the relay 12 and the first and second current-carrying bus bars 124a, 124b is increased, thereby suppressing heat generation of the relay 12. Therefore, the same effects as those of the first embodiment are achieved.

[0069] In particular, in the circuit assembly 120 of the second embodiment, since the heat capacity increasing component 122 is separate from the first and second current-carrying bus bars 124a, 124b, it is possible to adopt a material for the heat capacity increasing component 122 that is more likely to increase the heat capacity than the first and second current-carrying bus bars 124a, 124b. Alternatively, it is possible to reduce loosening of the bolt 18 when the relay 12 generates heat by adopting the same material (e.g., iron) as the material for the heat capacity increasing component 122. The shape of the heat capacity increasing component 122 is not limited to a rectangular block shape, and it may simply be a flat plate shape like a bus bar, or may be a shape that is likely to increase the heat capacity or that can suppress loosening of the bolt 18 when heat is generated.

[0070] Also in the second embodiment, the heat capacity increasing component 122 is provided overlapping the front surface 79 of the bolt fastening portion 72 of the first and second current-carrying bus bars 124a, 124b. Therefore, the electrical paths from the first and second connecting portions 14a, 14b to the external connecting portion 76 and the fuse connecting portion 86 and the thermal paths to the heat transfer portions 74, 74 are shortened, preventing an increase in conduction resistance and achieving rapid heat transfer.

[0071] <Embodiment 3> Hereinafter, the third embodiment of the present disclosure will be described with reference to Figs. 8 and 9. The circuit assembly 130 of the third embodiment has a similar basic structure to the circuit assembly 120 of the second embodiment, but differs in that metal caps 132, 132 as heat capacity increasing parts are attached to the bolts 18 instead of the heat capacity increasing part 122. Note that the third embodiment employs first and second current-carrying bus bars 124a, 124b having the same structure as the second embodiment. Figs. 8 and 9 show the circuit assembly 130 with the cover member 30 constituting the case 22 removed.

[0072] That is, in the third embodiment, the heat capacity increasing part is constituted by the cap 132 attached to the head of the bolt 18. Therefore, the cap 132 is formed with an accommodating recess 136 for accommodating the head of the bolt 18. As a result, the cap 132 is in thermal contact with the fastening portion A between the first and second current-carrying bus bars 124a, 124b and the first and second connecting portions 14a, 14b via the bolt 18. In the third embodiment, the cap 132 is formed of a metal having a high thermal conductivity. The cap 132 is suitably formed of, for example, iron, copper, aluminum, and alloys thereof. In short, the heat capacity increasing part is not limited to a mode in which it is fixed to the heat-generating member (relay 12) together with the current-carrying member (first and second current-carrying bus bars) by the fastening member (bolt 18).

[0073] The cap 132 is attached to the head of the bolt 18 after the first and second current-carrying bus bars 124a, 124b are fixed to the first and second connection portions 14a, 14b of the relay 12 by the bolt 18. Alternatively, the cap 132 may be attached to the head of the bolt 18, and then the first and second current-carrying bus bars 124a, 124b may be fixed to the first and second connection portions 14a, 14b of the relay 12 by the bolt 18. A portion of the cap 132 on the outer circumferential side of the accommodating recess 136 may or may not abut against the front surface 79 of the bolt fastening portion 72 of the first and second current-carrying bus bars 124a, 124b.

[0074] It is preferable that thermally conductive grease 138, which is a thermally conductive member, be provided between the inner surface of the accommodating recess 136 of the cap 132 and the head of the bolt 18. This ensures stable heat transfer from the bolt 18 to the cap 132, even if a gap occurs between the cap 132 and the bolt 18 due to, for example, manufacturing errors.

[0075] In the circuit configuration 130 of the third embodiment, the bolt 18 that fixes the relay 12 to the first and second current-carrying bus bars 124a, 124b is provided with a cap 132 that increases the thermal capacity of the first and second connection portions 14a, 14b. As a result, the cap 132 suppresses a rise in temperature of the bolt 18, and therefore the first and second connection portions 14a, 14b, when the relay 12 generates heat.

[0076] In particular, in the third embodiment, since the cap 132 is made of metal, the heat capacity can be easily increased. In addition, since the cap 132 is a separate member from the first and second current-carrying bus bars 124a, 124b and the bolt 18, it is possible to adopt a material for the cap 132 that is more likely to increase the heat capacity than the first and second current-carrying bus bars 124a, 124b and the bolt 18. It is also possible to make it difficult for a gap to occur between the cap 132 and the bolt 18 when the relay 12 generates heat by making the linear expansion coefficients of the cap 132 and the bolt 18 close to each other or by making the cap 132 and the bolt 18 of the same material. It is preferable that the cap 132 is made of a metal having a lower specific gravity than copper or iron. This is because the influence of vibration of the bolt 18 can be reduced by using a metal having a lower specific gravity.

[0077] <Embodiment 4> A fourth embodiment of the present disclosure will be described below with reference to Fig. 10. A circuit assembly 140 of the fourth embodiment has a similar basic structure to the circuit assembly 10 of the first embodiment, but differs in that a synthetic resin cap 142 serving as a heat capacity increasing part is attached to the bolt 18. That is, the cap 142 is in thermal contact with the fastening portion A between the first and second current-carrying bus bars 16a, 16b and the first and second connection portions 14a, 14b via the bolt 18. Note that Fig. 10 shows the circuit assembly 140 with the cover member 30 constituting the case 22 removed.

[0078] In the circuit assembly 140 of the fourth embodiment, the cap 142 for increasing the heat capacity of the first and second connection parts 14a, 14b is attached to the bolt 18 for fixing the relay 12 to the first and second current-carrying bus bars 16a, 16b. In addition to the heat capacity increasing part 20 of the first embodiment, the cap 142 also has an effect of suppressing a temperature rise. In particular, in the fourth embodiment, the cap 142 made of synthetic resin, which is relatively softer than metal, is used. This allows the head of the bolt 18 to be in close contact with the cap 142 with almost no gap, and a sufficient contact area between the cap 142 and the head of the bolt 18 can be secured. This allows heat to be stably transferred from the bolt 18 to the cap 142. Furthermore, the use of the synthetic resin cap 142 ensures electrical insulation at the head of the bolt 18.

[0079] <Other embodiments> The technology described in this specification is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope of the technology described in this specification.

[0080] (1) In the above embodiment, the heat capacity increasing parts 20, 122 and the caps 132, 142 are provided at the fastening part A between the first and second connection parts 14a, 14b of the relay 12, which is a heat generating part, and the first and second current-carrying bus bars 16a, 124a, 16b, 124b. However, this is not limited to this. The heat capacity increasing parts may be provided at the fastening parts between the connection parts of the fuse or current sensor that generates heat when current is passed through them and the current-carrying members (for example, the second to fourth current-carrying bus bars in the above embodiment). That is, the heat generating part according to the present disclosure may be a fuse or a current sensor instead of or in addition to the relay. Note that it is not necessary to provide a plurality of heat generating parts, and it is sufficient to provide at least one.

[0081] (2) In the third embodiment, a cap 132 was used as the heat capacity increasing part instead of the heat capacity increasing part 20 of the first embodiment. However, the cap 132 may be used in addition to the heat capacity increasing parts 20 and 122 of the first and second embodiments.

[0082] (3) The heat capacity increasing parts 20, 122 and the caps 132, 142 of the above-mentioned embodiments may be adopted in combination of at least two in a manner other than that of the above-mentioned embodiment 4. That is, for example, the heat capacity increasing parts as in the above-mentioned embodiments 1 and 2 may be adopted in combination at the fastening parts between the first and second connection parts of the relay and the first and second current-carrying bus bars. Alternatively, the heat capacity increasing parts as in the above-mentioned embodiments 1 and 2 may be adopted at the fastening parts between the first and second connection parts of the relay and the first and second current-carrying bus bars, and the heat capacity increasing parts as in the above-mentioned embodiments 3 and 4 may be provided at the fastening parts between the connection parts of the fuse or the current sensor and the current-carrying member.

[0083] (4) In the above embodiment, the heat capacity increasing parts 20, 122 and the caps 132, 142 as heat capacity increasing parts are provided at the fastening parts A between the first and second connection parts 14a, 14b and the first and second current-carrying bus bars 16a, 124a, 16b, 124b in the relay 12, respectively, but this is not limited thereto. The heat capacity increasing parts may be provided at a fastening part between at least one of the connection parts and a current-carrying member. The same applies to the case where a heat capacity increasing part is provided at a fastening part between a connection part and a current-carrying member in a fuse or a current sensor.

[0084] (5) A heat dissipation mechanism (e.g., heat transfer section 74, 102, 112 and heat conductive sheet 114, 116, etc.) that dissipates heat from components that generate heat when current is applied (e.g., relay 12, fuse 24, current sensor 26 in the embodiments) is not essential. Even if a heat dissipation mechanism is provided, it is not limited to the structure as in the above-described embodiments, and any conventionally known heat dissipation mechanism may be used. For example, a through hole may be provided in the case (e.g., the bottom wall of the base member) so that the heat transfer section is in thermal contact with the heat sink directly or via a heat conductive member (e.g., a heat conductive sheet).

[0085] (6) In the above embodiment, the relay 12, the fuse 24, the current sensor 26, and the first to fourth conductive bus bars 16a, 124a, 16b, 124b, 90, 92 were all fixed to the cover member 30, but at least one of them may be fixed to the base member.

[0086] (7) In the above embodiment, bolts 18 are used as an example of a fastening member. However, the fastening member is not limited to bolts, and any conventionally known fastening member capable of fastening a current-carrying member and a connection portion, such as rivets, can be used.

[0087] (8) The heat capacity increasing parts according to the present disclosure are not limited to the shapes and materials exemplified in the above embodiments, and as long as the parts are provided with a heat capacity greater than that of the electrically conductive member alone, the shapes and materials are not limited. [Explanation of symbols]

[0088] 10 Circuit structure (embodiment 1) 12 Relay (heat generating component) 14 Connection 14a First connection part 14b Second connection part 16 Conductive busbar (conductive member) 16a First current busbar 16b Second current busbar 18 Bolts (fastening members) 20 Heat capacity increasing parts 22 cases 24. Fuse 26 Current Sensor 28 Base material 30 Lid member 32 Bottom wall 34 Peripheral wall 36 First storage recess 38 Steps 40 Second accommodation recess 42 Steps 44 Upper bottom wall 46 Peripheral wall 48a,48b opening 50 Bolt hole 52 Relay body 54 Insulating plate 56 Legs 60 Fuse body 62 Connection 66 Sensor body 68 Connection 72 Bolt fastening section 74 Heat transfer section 76 External connection part 78 Contact surface 79 Front (opposite side of contact surface) 80 Holding part 82,84 Bolt insertion holes 86 Fuse connection 88 Bolt insertion hole 90 3rd current busbar 92 4th current busbar 94 Fuse connection 96 Sensor connection 102 Heat transfer section 104 Sensor connection 106 External connection part 110 Bolt insertion hole 112 Heat transfer section 114 Thermally conductive sheet (thermal conductive material) 116 Thermal Conductive Sheet 118 Heat sink 120 Circuit structure (embodiment 2) 122 Heat capacity increasing parts 124a First conductive bus bar (conductive member) 124b Second conductive bus bar (conductive member) 126 Through hole 130 Circuit structure (embodiment 3) 132 Cap (heat capacity increasing part) 136 Storage recess 138 Thermally conductive grease (thermal conductive material) 140 Circuit structure (embodiment 4) 142 Cap (heat capacity increasing part) A Fastening part

Claims

1. A heat generating component that generates heat when current is applied; A conductive member connected to a connection portion of the heat generating component; a fastening member for fastening the current-carrying member to the connection portion; a heat capacity increasing part that is in thermal contact with a fastening portion of the current-carrying member and the connection part and increases a heat capacity of the connection part of the heat generating component, the current-carrying member has a fastening portion fastened to the connection portion and a heat transfer portion extending from the fastening portion, the heat capacity increasing part is superimposed on a surface of the current-carrying member opposite to a contact surface thereof with the connection portion, the heat capacity increasing part is formed by one end of the fastening part of the current-carrying member, and is folded back and overlapped on a surface of the current-carrying member opposite to the contact surface with the connection part, The heat transfer portion extends from the other end of the fastening portion, The current-carrying member has an external connection portion and a crank-shaped bent portion, and the heat transfer portion and the external connection portion are connected by the crank-shaped bent portion. circuit construct.

2. A heat generating component that generates heat when electricity is applied; A conductive member connected to a connection portion of the heat generating component; a fastening member for fastening the current-carrying member to the connection portion; a heat capacity increasing part that is in thermal contact with a fastening portion of the current-carrying member and the connection part and increases a heat capacity of the connection part of the heat generating component, the current-carrying member has a fastening portion fastened to the connection portion and a heat transfer portion extending from the fastening portion, the heat capacity increasing part is superimposed on a surface of the current-carrying member opposite to a contact surface thereof with the connection portion, When the heat generating component is placed on the heat transfer section, the connection portion of the heat generating component is located on a side surface, The fastening portion protrudes upward from the heat transfer portion, and has a bolt insertion hole that is long in the vertical direction and penetrates the contact surface and the heat capacity increasing part, and the fastening portion is fastened to the connection portion by a fastening bolt that is inserted through the bolt insertion hole. circuit construct.

3. 3. The circuit assembly according to claim 1, further comprising a heat conductive member and a case, the current carrying member being in thermal contact with the case via the heat conductive member.

4. The heat capacity increasing part is made of metal, 4. The circuit assembly according to claim 1, wherein the heat capacity increasing component is fastened to the connection portion together with the current-carrying member by the fastening member.

5. 2. The circuit assembly according to claim 1, wherein the conductive member is provided with a retaining portion that maintains an overlapping state between the one end of the fastening portion of the conductive member constituting the heat capacity increasing component and a surface of the conductive member opposite to a contact surface with the connection portion.

6. 6. The circuit assembly according to claim 4, wherein the coefficient of linear expansion of the heat capacity increasing part is 1 / 3 to 3 times the coefficient of linear expansion of the fastening member.

7. 7. The circuit assembly according to claim 4, wherein the heat capacity increasing part and the fastening member are made of the same material.

8. 3. The circuit assembly according to claim 1, wherein the heat capacity increasing part is constituted by a cap attached to the fastening member.

9. The circuit assembly of claim 8 , wherein the cap is made of metal.

10. The circuit assembly according to claim 9 , wherein a thermally conductive member is provided between the cap and the fastening member.

11. 9. The circuit assembly according to claim 8, wherein the cap is made of a synthetic resin.

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