Circuit structure

Abstract

The present invention provides a circuit structure having a novel configuration that has durability against reaction forces on a heat conduction element and can improve the heat dissipation efficiency of a heating element. The circuit structure (10) includes: a heating element (14); bus bars (28, 30) connected to connection portions (82, 84) of the heating element (14); housings (24, 26) that house the heating element (14) and the bus bars (28, 30); an elastic heat conduction element (48) in thermal contact with the bus bars (28, 30); a pressing portion (74) provided on the housings (24, 26) to bring the bus bars (28, 30) into contact with the heat conduction element (48); and a reinforcing wall portion (78) protruding to the outside of the housings (24, 26) to reinforce the pressing portion (74).

Description

Technical Field

[0001] The present disclosure relates to a circuit structure including a heating element. Background Art

[0002] Conventionally, a circuit structure including a heating element such as a relay has been mounted in a vehicle. For example, Patent Document 1 discloses a circuit structure including a relay that intermittently supplies power from a battery to a motor or a generator connected via a converter as a load on the vehicle side.

[0003] In a heating element such as a relay used in such a circuit structure, since a large current flows, Joule heat proportional to the square of the current amount is generated, and the heat generation amount also becomes large. Therefore, in Patent Document 1, a structure for dissipating heat of the relay using an intermediate portion of a bus bar that connects a connection portion of the relay housed in a case and a connection terminal of a battery disposed outside the case is proposed. Specifically, a structure is disclosed in which, at an intermediate portion of a bus bar extending outside a case housing a relay, the bus bar is brought into contact with a chassis or a box housing the entire power supply device via a heat conduction element, and heat generated by the relay is thermally conducted to the chassis or the box to dissipate heat.

[0004] Prior Art Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-79093 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the structure of Patent Document 1, it is necessary to extend the heat dissipation portion provided on the bus bar to other components provided outside the case for a long distance, and it is inevitable that the distance between the connection portion of the relay and the heat dissipation portion becomes large. Therefore, there is a problem that heat generated in the relay cannot be dissipated efficiently. In addition, since the heat conduction element is pressed by the bus bar extending outside the case, when the pressing force becomes large due to dimensional interference between the bus bar and the like, displacement of the bus bar or breakage of other devices may occur due to the reaction force of the heat conduction element.

[0008] Therefore, the present invention discloses a circuit structure having a novel structure that has durability against the reaction force of the heat conduction element and can improve the heat dissipation efficiency of the heating element.

[0009] Means for Solving the Problems

[0010] The circuit structure of the present disclosure is a circuit structure having: a heating element; a bus bar connected to a connection portion of the heating element; a housing that houses the heating element and the bus bar; an elastic heat conduction element in thermal contact with the bus bar; a pressing portion provided on the housing to bring the bus bar into contact with the heat conduction element; and a reinforcing wall portion that protrudes outward from the housing to reinforce the pressing portion.

[0011] Advantageous Effects of the Invention

[0012] According to the present disclosure, durability against reaction forces of the heat conduction element is provided and heat dissipation efficiency of the heating element can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an overall perspective view showing the circuit structure according to Embodiment 1 of the present disclosure.

[0014] Figure 2 It is a diagram schematically showing an electrical structure in a path from a storage battery to a load.

[0015] Figure 3 It is Figure 1 an exploded perspective view of the circuit structure shown.

[0016] Figure 4 It is Figure 1 a top view of the circuit structure shown.

[0017] Figure 5 It is Figure 4 an enlarged sectional view taken along line V-V in

[0018] Figure 6 It is Figure 4 an enlarged sectional view taken along line VI-VI in

[0019] Figure 7 It is a top view showing the circuit structure according to Embodiment 2 of the present disclosure, and is a view corresponding to Figure 4 the above.

[0020] Figure 8 It is an enlarged sectional view showing the circuit structure according to Embodiment 3 of the present disclosure, and is a view corresponding to Figure 5 the above. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] <Description of Embodiments of the Present Disclosure>

[0022] First, embodiments of the present disclosure will be listed and described.

[0023] The circuit structure of the present disclosure is

[0024] (1) The circuit structure includes: a heating element; a bus bar connected to the connecting portion of the heating element; a housing that houses the heating element and the bus bar; an elastic heat conduction element in thermal contact with the bus bar; a pressing portion provided on the housing to bring the bus bar into contact with the heat conduction element; and a reinforcing wall portion protruding outward from the housing to reinforce the pressing portion.

[0025] In the circuit structure according to the present disclosure, the bus bar connected to the connecting portion of the heating element is in thermal contact with the heat conduction element. Through the pressing portion provided on the housing that houses the heating element, the bus bar and the heat conduction element are reliably in contact. Therefore, it is possible to advantageously prevent the decrease in the close contact between the bus bar and the heat conduction element, which may lead to a reduction in the heat transfer efficiency. In addition, it is possible to reliably thermally contact the heat conduction element near the heating element without leading the bus bar connected to the connecting portion of the heating part of the heating element outside the housing. As a result, the heat generated by the heating element can be transferred to the housing and the components outside the housing via the bus bar and the heat conduction element, and the heat dissipation efficiency of the heating element can be improved.

[0026] Moreover, the pressing portion is reinforced by the reinforcing wall portion protruding outward from the housing. Therefore, even when the pressing force of the pressing portion pressing the heat conduction element becomes high due to dimensional interference between the housing or the bus bar, etc., it is possible to prevent the breakage of the pressing portion that receives the reaction force, and it is also possible to improve the durability of the pressing portion, the housing, and the circuit structure.

[0027] In addition, the pressing portion only needs to be an element that brings the bus bar into contact with the heat conduction element, and it is not necessarily required to press the bus bar against the heat conduction element. However, by adopting a structure that presses the bus bar against the heat conduction element, it is possible to advantageously avoid the decrease in the close contact between the bus bar and the heat conduction element caused by tolerances, etc. In addition, the heat conduction element can either be placed on the wall portion of the housing and thermally contact the components outside the housing via the housing, or thermally contact the components outside the housing via the opening provided in the housing. In addition, the bus bar connected to the connecting portion of the heating element includes both the bus bar used as a conducting element and the bus bar only used for heat dissipation.

[0028] (2) Preferably, the pressing portion is provided at a position on the housing facing the heat conduction element with the bus bar interposed therebetween, and the reinforcing wall portion is prominently provided on the surface of the pressing portion opposite to the contact surface with the heat conduction element. This is because, in the pressing portion provided on the housing, the reinforcing wall portion is provided on the surface opposite to the facing surface with the heat conduction element, so the pressing portion can be reliably reinforced by the reinforcing wall portion. Moreover, in the pressing portion, the reinforcing wall portion is prominently provided on the surface opposite to the contact surface with the heat conduction element, so a heat dissipation path from the bus bar and the heat conduction element via the reinforcing wall portion can be constructed, and the heat dissipation of the heating element can be more advantageously achieved.

[0029] (3) Preferably, the reinforcing wall portion is configured to include a plurality of reinforcing plates arranged in parallel at intervals. This is because, since the reinforcing wall portion includes a plurality of reinforcing plates arranged in parallel at intervals, each reinforcing plate functions as a heat sink, and a further heat dissipation effect via the reinforcing plates is exerted. In addition, the reinforcing wall portion of this embodiment can be provided in any shape as long as it includes a portion where a plurality of reinforcing plates are arranged in parallel at intervals. For example, a fin shape, a grid pattern, a honeycomb structure, etc. can also be included in this embodiment.

[0030] (4) Preferably, a metal portion is embedded in the reinforcing wall portion, and a part of the metal portion protrudes to the outside of the reinforcing wall portion. This is because the reinforcing effect and heat dissipation effect of the reinforcing wall portion on the pressing portion are further improved.

[0031] (5) Preferably, a holding structure is provided, and the holding structure holds the pressing portion in a state of pressing against the bus bar and the heat conduction element. This is because the bus bar and the heat conduction element can be stably held in a tightly contacting state, and the desired heat dissipation property can be stably maintained. For example, it is effective to bolt the pressing portion provided on the upper housing to the lower housing, so that the bus bar is reliably pressed against the heat conduction element placed on the lower housing via the pressing portion.

[0032] <Details of the Embodiment of the Present Disclosure>

[0033] Hereinafter, a specific example of the circuit structure body of the present disclosure will be described with reference to the drawings. In addition, the present disclosure is not limited to these examples, but is shown by the claims, and intends to include all changes within the meaning equivalent to the claims and the scope.

[0034] <Embodiment 1>

[0035] Hereinafter, with reference to Figures 1 to 6 Embodiment 1 of the present disclosure will be described. The circuit structure body 10 is mounted on a vehicle (not shown) such as an electric vehicle or a hybrid vehicle, for example. For example, as Figure 2 shown, the circuit structure body 10 is used to connect a driving battery, which is a heating element, to a vehicle-side load 16 via a main relay 14. Here, the driving battery refers to the battery 12 and is used as a battery for supplying power to an electric motor (not shown) that drives the vehicle. In addition, the circuit structure body 10 can be arranged in any orientation, but hereinafter, the Z direction shown in Figure 1 is taken as the upper direction, the Y direction as the width direction, and the X direction as the length direction for description. In addition, the lower right in the X direction is the front, and the opposite direction is the rear. In addition, for a plurality of identical elements, sometimes only a part of the elements are labeled with reference numerals, and other elements are omitted from the reference numerals.

[0036] <Circuit Structure 10>

[0037] As shown in Figure 2 , the circuit structure 10 includes a circuit structure 10a provided on the positive electrode side and a circuit structure 10b provided on the negative electrode side. The positive electrode side of the battery 12 is connected to the input side of the circuit structure 10a, and the negative electrode side of the battery 12 is connected to the input side of the circuit structure 10b. The positive electrode side of the vehicle-side load 16 is connected to the output side of the circuit structure 10a, and the negative electrode side of the vehicle-side load 16 is connected to the output side of the circuit structure 10b. Main relays 14 that connect the battery 12 to the vehicle-side load 16 are respectively connected between the input sides and the output sides of the circuit structure 10a and the circuit structure 10b. In addition, a precharge circuit 22 in which a precharge relay 18 and a precharge resistor 20 are connected in series in a manner of bypassing the main relay 14 is connected to each of the main relays 14. Further, in Embodiment 1 of the present disclosure, as shown in Figure 2 , the precharge resistor 20 is connected to the output side of the precharge relay 18. In addition, both the main relay 14 and the precharge relay 18 are relays that switch the contact portion between on and off by moving the contact portion in a state where the excitation coil is energized, and the on / off control is performed by a control circuit (not shown). As described above, the circuit structures 10a and 10b have substantially the same configuration.

[0038] <Battery 12>

[0039] The battery 12 is formed by connecting a plurality of rechargeable secondary batteries in series to increase the output voltage, and is set to, for example, 100V to 400V. Alternatively, a plurality of secondary batteries may be connected in parallel to increase the current capacity. The secondary battery may be a lithium-ion secondary battery, a lithium polymer secondary battery, a nickel-metal hydride battery, or the like. Alternatively, instead of or in addition to the secondary battery, a capacitor such as an electric double layer capacitor (EDLC) may be used. In this specification, the secondary battery also includes a capacitor.

[0040] <Vehicle-Side Load 16>

[0041] The vehicle-side load 16 includes, for example, a large-capacity capacitor having a capacitance of 200 μF to 5000 μF. When the main relay 14 is switched to the on state in a state where the capacitor is completely discharged, a large charging current flows to charge the capacitor. The large charging current causes damage to the contact portion of the main relay 14. Therefore, the precharge circuit 22 is provided to prevent problems caused by the charging current. In Embodiment 1 of the present disclosure, as shown in Figure 2As shown, a precharge circuit 22 is provided in parallel with the main relay 14. In order to limit the charging current of the capacitor of the vehicle-side load 16, a precharge resistor 20 is connected in series with the precharge relay 18 in the precharge circuit 22. The precharge resistor 20 limits the charging current of the capacitor of the vehicle-side load 16 to a relatively small value when the precharge relay 18 and the main relay 14 are switched to the on state.

[0042] <Circuit structure 10>

[0043] For example, as Figure 1 and Figure 3 shown, the circuit structure 10 includes a lower housing 24 located below when mounted on the vehicle and an upper housing 26 located above, and the housing is formed by the lower housing 24 and the upper housing 26. In the state where the lower housing 24 and the upper housing 26 are assembled, various busbars such as a positive busbar 28 and a negative busbar 30 connecting the battery 12 and the main relay 14 are accommodated inside.

[0044] <Lower housing 24>

[0045] The lower housing 24 is formed by injection molding an insulating synthetic resin into a predetermined shape. The synthetic resin forming the lower housing 24 may also contain fillers such as glass fibers. For example, as Figure 3 shown, the lower housing 24 has a generally rectangular box shape that opens upward as a whole, and has a bottom wall 32 and a peripheral wall 34 protruding upward from the edge portion of the bottom wall 32. As Figure 3 and Figure 4 shown, engaging portions 36 are respectively provided on the four sides of the bottom wall 32 of the lower housing 24 and protruding upward at four portions at the base end of the peripheral wall 34.

[0046] As Figure 3 and Figure 4 shown, on one side in the width direction of the circuit structure 10 ( Figure 4 in this case, the left side in the Y direction), a circuit structure 10a provided on the positive side is provided, and on the other side in the width direction of the circuit structure 10 ( Figure 4 in this case, the right side in the Y direction), a circuit structure 10b provided on the negative side is provided. As described above, since the circuit structures 10a and 10b have substantially the same structure, the circuit structure 10a will be described as an example here. As Figure 3 shown, at the central portion in the length direction (X direction) of the bottom wall 32 of the lower housing 24 where the circuit structure 10a is formed, a square tube-shaped main relay fixing portion 38 for bolt-fastening the leg portion 88 of the main relay 14 to be described later protrudes upward from three portions. A circular nut is accommodated inside the main relay fixing portion 38. In addition, on the front side in the length direction of the bottom wall 32 of the lower housing 24 ( Figure 3In the [right lower oblique side in the X direction], at two parts separated in the width direction (Y direction), there are protruding positive bus bar fixing parts 40 in the shape of a square tube, and an annular nut 42 is accommodated in the positive bus bar fixing part 40. The battery connection part 56 of the main relay input side bus bar 28a and the vehicle side load connection part 58 of the main relay output side bus bar 28b, which will be described later, are respectively bolted to the positive bus bar fixing part 40. Moreover, on the bottom wall 32 between the main relay fixing part 38 and the positive bus bar fixing part 40, fixing parts 44 are provided at three parts separated in the width direction. The fixing parts 44 penetrate the bottom wall 32 in the plate thickness direction and protrude downward, and the pressing part 74 of the upper housing 26, which will be described later, is bolted to the lower housing 24. An annular nut 46 is accommodated in the fixing part 44.

[0047] <Heat dissipation sheets 48, 50>

[0048] As Figure 3 And Figure 5 , Figure 6 shown, on the bottom wall 32 between the fixing parts 44 of the lower housing 24, there is a heat dissipation sheet 48 that constitutes a rectangular flat plate-shaped heat conduction element, and on the back side of the bottom wall 32 relative to the heat dissipation sheet 48, there is a heat dissipation sheet 50 that constitutes a heat conduction element. The heat dissipation sheets 48, 50 are in the shape of flat sheets in the vertical direction and are made of a synthetic resin with a higher thermal conductivity than air. Specifically, silicone-based resins, non-silicone-based acrylic resins, ceramic-based resins, etc. can be used. More specifically, for example, heat dissipation gap fillers, heat conduction greases, heat conductive silicone rubbers, etc. made of silicone-based resins can be cited. The heat dissipation sheets 48, 50 have flexibility and elasticity, and can elastically deform in such a way that the thickness dimension changes according to the force applied in the vertical direction. In addition, in the present embodiment, the heat dissipation sheets 48, 50 are used as heat conduction elements, but it is not limited thereto, and any elastic heat conduction element with an arbitrary shape can be used.

[0049] <Positive bus bar 28 and negative bus bar 30>

[0050] As Figure 3 And Figures 5 to 6As shown, the positive bus bar 28 and the negative bus bar 30 are arranged on the bottom wall 32 of the lower housing 24. In addition, the positive bus bar 28 and the negative bus bar 30 are formed by stamping a metal plate into a predetermined shape. As the metal constituting the positive bus bar 28 and the negative bus bar 30, metals with high thermal conductivity and low resistance such as copper, copper alloy, aluminum, and aluminum alloy can be appropriately selected. As described above, since the circuit structure 10a and the circuit structure 10b have substantially the same structure, the positive bus bar 28 of the circuit structure 10a will be taken as an example for description herein. Both the main relay input side bus bar 28a and the main relay output side bus bar 28b constituting the positive bus bar 28 extend along the length direction ( Figure 3 in which, the X direction), the end on the main relay 14 side is bent in an L shape, and the other end is bent in a crank shape. The ends of the main relay input side bus bar 28a and the main relay output side bus bar 28b on the main relay 14 side respectively become the first power terminal connection part 52 and the second power terminal connection part 54 that are connected to the first power terminal 82 and the second power terminal 84 constituting the connection part of the main relay 14 described later. The other ends of the main relay input side bus bar 28a and the main relay output side bus bar 28b respectively become the battery connection part 56 and the vehicle side load connection part 58. The central parts of the main relay input side bus bar 28a and the main relay output side bus bar 28b in the length direction are formed parallel to the bottom wall 32 of the lower housing 24, and the heat transfer part 60 that is arranged on the heat dissipation fin 48 and is in thermal contact with the heat dissipation fin 48.

[0051] <Upper housing 26>

[0052] The upper housing 26 is formed by injection molding an insulating synthetic resin into a predetermined shape. The synthetic resin constituting the upper housing 26 may also contain fillers such as glass fiber. For example, as Figure 3 shown, the upper housing 26 has a substantially box shape that opens downward and has a peripheral wall 64 protruding downward formed at the outer peripheral edge of a substantially horizontally long rectangular flat upper wall 62. As Figure 3 and Figure 4 shown, on the peripheral walls 64 of the four sides of the upper housing 26, cut-shaped engaged parts 66 are respectively provided at four positions separated in the circumferential direction at the protruding ends of the peripheral walls 64. On the front side and the rear side of the upper wall 62 of the upper housing 26 ( Figure 4 in which, the lower side and the upper side in the X direction) in the width direction (Y direction) at three separated positions, bolt fastening parts 68 for fixing the circuit structure 10 of the present disclosure to a predetermined part of a vehicle (not shown) are respectively provided. As described above, in the upper housing 26, the circuit structure 10a is also taken as an example for description. As Figure 3 and Figure 4 shown, on the upper surface of the upper wall 62 of the upper housing 26, from the front side (Figure 4 In it, a battery connection part storage part 70a, a vehicle-side load connection part storage part 70b, a main relay mounting part 72a, a pre-charge relay mounting part 72b, and a pre-charge resistor mounting part 72c are provided starting from the lower side in the X direction. The battery connection part 56, the vehicle-side load connection part 58, the main relay 14, the pre-charge relay 18, and the pre-charge resistor 20 are mounted on these mounting parts. In addition, a pressing part 74 is provided between the battery connection part storage part 70a and the vehicle-side load connection part storage part 70b and the main relay mounting part 72a. The pressing part 74 has a substantially rectangular flat plate shape in a plan view, and on the upper wall 62 of the upper case 26 constituting the pressing part 74, a plurality of (in this embodiment, seven) reinforcing plates 76 are formed extending along the width direction (Y direction) and arranged in parallel at intervals in the length direction (X direction). The reinforcing wall part 78 is configured to include the plurality of reinforcing plates 76. The reinforcing wall part 78 protrudes upward, that is, to the outside of the upper case 26 and is exposed to the outside of the reinforcing wall part 78 as shown in, for example, Figure 1 and is provided to strengthen the pressing part 74. In addition, in the pressing part 74, bottomed cylindrical bolt fastening parts 80 opening upward are formed at three positions separated in the width direction (Y direction).

[0053] <Main relay 14>

[0054] The main relay 14 is a so-called mechanical relay having a contact part and a coil part (not shown) inside it. For example, as shown in Figure 3 , on the front surface of the main relay 14, a first power terminal 82 and a second power terminal 84 are arranged in the width direction (Y direction). By passing a current through the first power terminal 82 and the second power terminal 84, heat is generated at the contact part of the main relay 14 and heat conduction is performed to the first power terminal 82 and the second power terminal 84. Threaded holes 86 (refer to Figure 5 ) are formed in the first power terminal 82 and the second power terminal 84 respectively. As shown in Figure 3 and Figure 4 , at three positions at the lower end part of the main relay 14, feet 88 having a substantially rectangular shape when viewed from above protrude outward. Bolt insertion holes 92 through which bolts 90 are inserted are formed through the feet 88. In addition, at the four corners of the lower end part of the main relay 14 where the feet 88 are not provided, a connector storage part 94 protruding outward in the width direction (Y direction) is provided. By mounting an external connector (not shown) in the connector storage part 94, the on / off of the main relay 14 is switched.

[0055] <Installation method of this embodiment>

[0056] The following is a brief description of the installation method of the present embodiment. The installation method of the present embodiment is also described by taking the circuit structure 10a as an example as described above. First, for the lower housing 24, a heat conductive sheet 48 is pasted on the bottom wall 32 between the fixing parts 44, and a heat conductive sheet 50 is pasted on the back side of the bottom wall 32 relative to the heat conductive sheet 48. Next, in a state where the main relay input side bus bar 28a and the main relay output side bus bar 28b constituting the positive bus bar 28 are arranged in a manner extending along the length direction (X direction), the heat transfer part 60 is arranged on the heat conductive sheet 48. In this state, the battery connection part 56 of the main relay input side bus bar 28a and the vehicle side load connection part 58 of the main relay output side bus bar 28b are bolted to the positive bus bar fixing part 40 of the lower housing 24, respectively. Next, the upper housing 26 is installed from above in a manner covering such a lower housing 24. Thus, the engaging portion 36 of the lower case 24 and the engaged portion 66 of the upper case 26 are engaged and fixed to each other. Next, the leg portion 88 of the main relay 14 is placed on the bolt fastening portion 96 provided at the peripheral portion of the main relay mounting portion 72a of the upper case 26. After the first power terminal connecting portion 52 of the main relay input side bus bar 28a and the second power terminal connecting portion 54 of the main relay output side bus bar 28b are bolted to the first power terminal 82 and the second power terminal 84 of the main relay 14, respectively, the leg portion 88 is fixed to the bolt fastening portion 96. As a result, the heat transfer portion 60 of the main relay input side bus bar 28a and the main relay output side bus bar 28b contacts the heat conductive sheet 48 through the pressing portion 74 provided on the upper case 26, and is further maintained in a pressed state. Furthermore, by engaging the engaging portion 36 of the lower housing 24 with the engaged portion 66 of the upper housing 26, the bolt fastening portion 80 of the pressing portion 74 of the upper housing 26 is bolted to the fixing portion 44 of the lower housing 24, so that the pressing portion 74 is kept pressed against the heat transfer portion 60 and the heat conducting sheet 48. As a result, as Figure 5 As shown, a pressing portion 74 is provided in the middle of the upper housing 26 at a position facing the heat conductive sheet 48 across the heat transfer portion 60, and a reinforcing wall portion 78 is protrudingly provided on the upper surface of the pressing portion 74 on the opposite side of the lower surface that is in thermal contact with the heat conductive sheet 48. Finally, the pre-charging relay 18 and the pre-charging resistor 20 are mounted on the pre-charging relay mounting portion 72b and the pre-charging resistor mounting portion 72c of the upper housing 26, thereby completing the circuit structure 10 of this embodiment. In addition, as shown in FIG. Figure 5 and Figure 6As shown, the circuit structure 10 can be fixed to a metal bracket 95 of a vehicle, for example, by bolt fastening portions 68 provided at six positions on the upper housing 26. Thus, a new heat dissipation path is provided from the heat transfer portion 60 through the heat conducting sheet 48, the lower housing 24, and the heat conducting sheet 50 to the metal bracket 95, and a further heat dissipation effect can be expected. For easy understanding, the metal bracket 95 is shown by a phantom line. Here, the metal bracket 95 is taken as an example for illustration, but it is not limited thereto. Instead of the metal bracket 95, the lower housing 24 or the heat conducting sheet 50 can be thermally connected to any component such as a battery housing.

[0057] According to the circuit structure 10 of the present disclosure configured as such, in the circuit structure 10a, end portions on the main relay 14 side of the main relay input side bus bar 28a and the main relay output side bus bar 28b constituting the bus bar are respectively connected to the first power terminal 82 and the second power terminal 84 constituting the connection portion of the main relay 14 as a heating element. In addition, central portions in the length direction (X direction) of these bus bars 28a and 28b are all provided as heat transfer portions 60 in thermal contact with the heat conducting sheet 48. Moreover, the heat transfer portion 60 is pressed against the heat conducting sheet 48 by a pressing portion 74 provided on the upper housing 26. Therefore, the bus bars 28a and 28b connected to the heating portions of the main relay 14 as a heating element, that is, the first power terminal 82 and the second power terminal 84, can be reliably in thermal contact with the heat conducting sheet 48 at the heat transfer portion 60 near the main relay 14. Thus, heat generation in the main relay 14 can be quickly transferred to the outside through the bus bars 28a and 28b and the heat conducting sheet 48 via the lower housing 24 and the upper housing 26, and the heat dissipation efficiency of the main relay 14 can be improved. Moreover, the pressing portion 74 is strengthened by a reinforcing wall portion 78 protruding to the outside of the upper housing 26. Therefore, even when the pressing force of the pressing portion 74 pressing the heat conducting sheet 48 becomes high due to dimensional tolerances of the housings 24 and 26 and the bus bars 28a and 28b, breakage of the pressing portion 74 receiving the reaction force can be prevented. Therefore, not only can the durability of the pressing portion 74, the housings 24 and 26 be improved, but also the durability of the circuit structure 10 itself can be improved.

[0058] In the pressing portion 74 provided on the upper housing 26, a reinforcing wall portion 78 is provided on the upper surface of the upper housing 26 on the side opposite to the lower surface facing the heat conductive sheet 48. The pressing portion 74 is easily and reliably reinforced by this reinforcing wall portion 78. Further, in the pressing portion 74, the reinforcing wall portion 78 protrudes from the upper surface on the side opposite to the lower surface in contact with the heat conductive sheet 48. Therefore, for example, a heat dissipation path can be constructed from the bus bars 28a and 28b via the reinforcing wall portion 78, and heat dissipation of the main relay 14 as a heat generating element can be more advantageously achieved. Further, since a plurality of reinforcing plates 76 arranged side by side at intervals are formed in the reinforcing wall portion 78, each reinforcing plate 76 functions as a heat sink and further heat dissipation effect via the reinforcing wall portion 78 is exhibited. Further, by the holding structure in which the bolt fastening portion 80 of the pressing portion 74 of the upper housing 26 is bolted to the fixing portion 44 of the lower housing 24, the pressing portion 74 is held in a state of being pressed against the heat transfer portion 60 and the heat conductive sheet 48. Thereby, the desired heat dissipation property can be stably maintained.

[0059] <Other Embodiments>

[0060] The technology described in this specification is not limited to the embodiments described in the above description and the drawings. For example, the following embodiments are also included in the technical scope of the technology described in this specification.

[0061] (1) In the above embodiment, the heat conductive sheets 48 and 50 are pasted on the upper and lower sides of the lower housing 24. However, it is not limited thereto, and the lower housing 24 may be directly brought into contact with the metal bracket 95 without using the heat conductive sheet 50. Further, the bus bar 28 may be in thermal contact with a heat conductive sheet of any element such as a battery case pasted to the outside of the circuit structure 10 through an opening provided in the lower housing 24 without passing through the lower housing 24. Further, as the heat conduction element, instead of or in addition to the heat conductive sheets 48 and 50, a heat dissipation gap filler or a heat conduction grease may be used.

[0062] (2) In the above embodiment, for example, the bus bars 28a and 28b are used as conduction elements. However, it is not limited thereto, and as long as it is a bus bar connected to the connection portion of the heat generating element, it may be a bus bar used only for heat dissipation.

[0063] (3) In the above embodiment, a plurality of reinforcing plates 76 extending in the width direction (Y direction) and arranged side by side at intervals in the length direction (X direction) are formed in the reinforcing wall portion 78. However, it is not limited thereto. For example, a grid pattern, a honeycomb structure, etc. in which a reinforcing plate extending in the length direction (X direction) is added to this structure may be adopted, and the reinforcing wall portion 78 may have any shape.

[0064] (4) In the circuit structure 10 of the present disclosure, the holding structure is formed by engaging the engaging portion 36 of the lower housing 24 with the engaged portion 66 of the upper housing 26 and bolting the bolt fastening portion 80 of the pressing portion 74 of the upper housing 26 to the fixing portion 44 of the lower housing 24, and the pressing portion 74 is held in a state of pressing against the heat transfer portion 60 and the heat conducting sheet 48, but it is not limited thereto. For example, as in the circuit structure 98 of Embodiment 2 shown in Figure 7 , the above-described holding structure using the bolt fastening portion 80 may not be employed, and the above-described holding structure may be realized only by the engaging structure of the engaging portion 36 of the lower housing 24 and the engaged portion 66 of the upper housing 26. Alternatively, the above-described holding structure may be constituted by an uneven fitting structure of an engaging protrusion (not shown) provided on the lower surface of the pressing portion 74 and an engaged portion (not shown) provided on the upper surface of the lower housing 24.

[0065] Moreover, the pressing portion 74 only needs to ensure the contact between the bus bar 28 and the heat conducting sheet 48, and it is not necessarily required to press the bus bar 28 against the heat conducting sheet 48.

[0066] (5) In the circuit structure 10 of the present disclosure, the reinforcing wall portion 78 is formed of an insulating synthetic resin, but it is not limited thereto. For example, as in the circuit structure 100 of Embodiment 3 shown in Figure 8 , a metal portion 106 is embedded in the reinforcing wall portion 102. That is, in the circuit structure 100, the base ends of thin-walled flat plate-shaped metal portions 106 are respectively embedded in the plurality of reinforcing plates 104 that constitute the reinforcing wall portion 102 of the pressing portion 74 that forms the upper housing 26. The portions of the respective metal portions 106 other than the base ends protrude outward from the reinforcing wall portion 102 formed by the respective reinforcing plates 104 in a state of protruding upward from the upper surfaces of the respective reinforcing plates 104 to the upper side of the upper housing 26 ( Figure 8 the Z direction).

[0067] Since the metal portion 106 is embedded in each of the reinforcing plates 104, the reinforcing wall portion 102 formed by the plurality of reinforcing plates 104 is more firmly reinforced. In addition, the plurality of reinforcing plates 104 extend along the width direction (Y direction) of the upper housing 26 and are arranged in parallel at intervals in the length direction (X direction), the same as in Embodiments 1 and 2. Therefore, the respective metal portions 106 protruding from the upper surfaces of the respective reinforcing plates 104 also extend along the width direction (Y direction) of the upper housing 26 and are arranged in parallel at intervals in the length direction (X direction). Accordingly, the heat dissipation performance of the heat dissipation path from the bus bars 28a and 28b through the reinforcing wall portion 102 is more favorably improved by the plurality of metal fin-structured metal portions 106.

[0068] Description of Reference Numerals

[0069] 10 Circuit Structure (Embodiment 1)

[0070] 10a Circuit Structure

[0071] 10b Circuit Structure

[0072] 12 Storage Battery

[0073] 14 Main Relay (Heating Element)

[0074] 16 Vehicle-Side Load

[0075] 18 Precharge Relay

[0076] 20 Precharge Resistor

[0077] 22 Precharge Circuit

[0078] 24 Lower Housing (Housing)

[0079] 26 Upper Housing (Housing)

[0080] 28 Positive Busbar (Busbar)

[0081] 28a Main Relay Input-Side Busbar (Busbar)

[0082] 28b Main Relay Output-Side Busbar (Busbar)

[0083] 30 Negative Busbar (Busbar)

[0084] 32 Bottom Wall

[0085] 34 Peripheral Wall

[0086] 36 Engaging Portion

[0087] 38 Main Relay Fixing Portion

[0088] 40 Positive Busbar Fixing Portion

[0089] 42 Nut

[0090] 44 Fixing Portion

[0091] 46 Nut

[0092] 48 Heat Conductive Sheet (Heat Conduction Element)

[0093] 50 Heat Conductive Sheet (Heat Conduction Element)

[0094] 52 First Power Terminal Connection Portion

[0095] 54 Second Power Terminal Connection Portion

[0096] 56 Storage Battery Connection Portion

[0097] 58 Vehicle side load connection part

[0098] 60 Heat transfer part

[0099] 62 Upper wall

[0100] 64 Peripheral wall

[0101] 66 Engaged part

[0102] 68 Bolt fastening part

[0103] 70a Battery connection part storage part

[0104] 70b Vehicle side load connection part storage part

[0105] 72a Main relay mounting part

[0106] 72b Pre-charge relay mounting part

[0107] 72c Pre-charge resistor mounting part

[0108] 74 Pressing part

[0109] 76 Reinforcing plate

[0110] 78 Reinforcing wall part

[0111] 80 Bolt fastening part

[0112] 82 First power terminal (connection part)

[0113] 84 Second power terminal (connection part)

[0114] 86 Threaded hole

[0115] 88 Leg part

[0116] 90 Bolt

[0117] 92 Bolt insertion through-hole

[0118] 94 Connector storage part

[0119] 95 Metal bracket

[0120] 96 Bolt fastening part

[0121] 98 Circuit structure (Embodiment 2)

[0122] 100 Circuit structure (Embodiment 3)

[0123] 102 Reinforcing wall part

[0124] 104 Reinforcing plate

[0125] 106 Metal part.

Claims

1. A circuit structure, comprising: A heating element; A bus bar connected to a connecting portion of the heating element; A housing that houses the heating element and the bus bar; An elastic heat conduction element in thermal contact with the bus bar; A pressing portion provided on the housing to bring the bus bar into contact with the heat conduction element; And A reinforcing wall portion that protrudes outward from the housing to reinforce the pressing portion, The pressing portion is provided at a position facing the heat conduction element with the bus bar interposed therebetween in the housing, The reinforcing wall portion protrudingly provided on a surface of the pressing portion opposite to a contact surface with the heat conduction element, The reinforcing wall portion is configured to include a plurality of reinforcing plates arranged side by side at intervals.

2. The circuit structure according to claim 1, wherein A metal portion is embedded in the reinforcing wall portion, and a part of the metal portion protrudes outward from the reinforcing wall portion.

3. The circuit structure according to claim 1 or 2, wherein The circuit structure has a holding structure that holds the pressing portion in a state of pressing against the bus bar and the heat conduction element.

Images