Circuit unit

Abstract

Disclosed is a circuit unit which makes it possible to suppress variations in a gap due to the tolerance between a heat dissipation object and a thermal contact part of a heat-generating component accommodated in a case, and to improve heat dissipation performance.　A circuit unit 10 comprises: a heat-generating component 22 which has a thermal contact part 14 that makes thermal contact with a heat dissipation object 12 and which has a fixation part 16 that is to be fixed to the heat dissipation object 12; a case 24 which holds the heat-generating component 22; a holding part 26 which protrudes inside the case 24 so as to hold the heat-generating component 22 in the case 24; an opening window 28 which is opened in the case 24 so that the thermal contact part 14 of the heat-generating component 22 is exposed to the outside of the case 24; and an insertion hole 30 which is opened in the case 24 and into which a fixation target part 42 provided to the heat dissipation object 12 is to be inserted, wherein when the fixation part 16 of the heat-generating component 22 is fixed to the fixation target part 42 inserted into the insertion hole 30, the heat-generating component 22 is separated from the holding part 26 and the thermal contact part 14 of the heat-generating component 22 makes thermal contact with the heat dissipation object 12.

Description

Circuit Unit

[0001] The present disclosure relates to a circuit unit.

[0002] Patent Document 1 discloses a circuit unit that is housed in a battery pack mounted on a vehicle and switches between energization and de-energization between the battery and a load. The circuit unit houses heat-generating components such as relays and ceramic pre-charge resistors in a case. To promote heat dissipation from these heat-generating components, the circuit unit of Patent Document 1 employs a structure in which the thermal contact portions of the heat-generating components fixed to the case are brought into contact with a metal outer housing, which is the heat dissipation target, via an elastic heat-conductive sheet, thereby ensuring a heat dissipation path for the heat-generating components.

[0003] JP 2009-181737 A

[0004] However, with the structure of Patent Document 1, it was unavoidable that the variation in the distance between the opposing surfaces of the heat-generating component and the outer housing would increase due to the accumulation of tolerances in the assembly of the inner case and the heat-generating component, and in the assembly of the inner case and the outer housing. As a result, when the tolerances increase, the thickness required for the elastic heat-conducting sheet interposed between the heat-generating component and the outer housing increases, which could lead to a decrease in heat dissipation performance.

[0005] Therefore, a circuit unit is disclosed that can improve heat dissipation performance by suppressing gap variations due to tolerances between the thermal contact portions of heat-generating components housed in a case and the heat dissipation target.

[0006] The circuit unit of the present disclosure comprises a heat-generating component having a thermal contact portion that thermally contacts a heat dissipation target and a fixing portion that is fixed to the heat dissipation target, a case that holds the heat-generating component, a fixing portion that protrudes from the inside of the case and holds the heat-generating component within the case, an opening window that penetrates the case and exposes the thermal contact portion of the heat-generating component to the outside of the case, and an insertion hole that penetrates the case and into which a fixing portion provided on the heat dissipation target is inserted, and by fixing the fixing portion of the heat-generating component to the fixing portion inserted into the insertion hole, the heat-generating component is separated from the fixing portion and the thermal contact portion of the heat-generating component is brought into thermal contact with the heat dissipation target.

[0007] According to the circuit unit of the present disclosure, it is possible to suppress gap variations due to tolerances between the thermal contact portions of the heat-generating components housed in the case and the heat dissipation target, thereby improving heat dissipation performance.

[0008] FIG. 1 is a perspective view showing a circuit unit according to a first embodiment fixed to a heat dissipation target. FIG. 2 is a perspective view showing the circuit unit shown in FIG. 1 with an upper case constituting the case removed. FIG. 3 is a plan view showing the circuit unit shown in FIG. 2 with the upper case removed. FIG. 4 is a longitudinal cross-sectional view showing an enlarged view of a main portion taken along the line IV-IV in FIG. 3. FIG. 5 is a longitudinal cross-sectional view showing an enlarged view of a main portion taken along the line V-V in FIG. 3. FIG. 6 is an exploded perspective view of the circuit unit shown in FIG. 1. FIG. 7 is a plan view showing a lower case constituting the circuit unit shown in FIG. 1. FIG. 8 is a perspective view showing the circuit unit shown in FIG. 1 before being fixed to a heat dissipation target, with the upper case removed. FIG. 9 is a longitudinal cross-sectional view of the circuit unit shown in FIG. 8 and corresponds to FIG. 5. FIG. 10 is a perspective view showing a circuit unit according to a second embodiment fixed to a heat dissipation target, with the upper case removed. 11 is a plan view showing the circuit unit shown in FIG. 10 with the upper case removed. FIG. 12 is an enlarged longitudinal cross-sectional view showing a main portion taken along the line XII-XII in FIG. 11. FIG. 13 is a perspective view showing a lower case constituting the circuit unit shown in FIG. 10. FIG. 14 is a perspective view showing the circuit unit shown in FIG. 10 in a state before it is fixed to a heat dissipation target, with the upper case removed. FIG. 15 is a longitudinal cross-sectional view of the circuit unit shown in FIG. 14 and corresponds to FIG. 12. FIG. 16 is an enlarged longitudinal cross-sectional view showing a main portion taken along the line XVI-XVI in FIG. 15.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be described below. A circuit unit of the present disclosure includes: (1) a heat-generating component having a thermal contact portion that thermally contacts a heat dissipation target and a fixing portion that is fixed to the heat dissipation target, a case that holds the heat-generating component, a fixing portion that protrudes from the inside of the case and holds the heat-generating component within the case, an opening that penetrates the case and exposes the thermal contact portion of the heat-generating component to the outside of the case, and an insertion hole that penetrates the case and into which a fixing portion provided on the heat dissipation target is inserted, and by fixing the fixing portion of the heat-generating component to the fixing portion inserted into the insertion hole, the heat-generating component is separated from the fixing portion and the thermal contact portion of the heat-generating component is brought into thermal contact with the heat dissipation target.

[0010] According to the circuit unit of this aspect, the fixing portion of the heat-generating component held in the case is directly fixed to the fixed portion of the heat dissipation target inserted into the case through the insertion hole provided in the case, thereby separating the heat-generating component from the holding portion of the case and bringing the thermal contact portion of the heat-generating component into thermal contact with the heat dissipation target. This eliminates any intervening members between the heat-generating component and the heat dissipation target, reducing tolerance-related variations in the distance between the thermal contact portion of the heat-generating component and the facing surface of the heat dissipation target compared to conventional structures. Furthermore, by fixing the fixing portion of the heat-generating component to the fixed portion of the heat dissipation target, the thermal contact portion of the heat-generating component exposed to the outside of the case through the opening in the case can be brought into thermal contact with the heat dissipation target, thereby stably maintaining contact between the thermal contact portion of the heat-generating component and the heat dissipation target. Therefore, gap variations due to tolerances between the thermal contact portion of the heat-generating component housed in the case and the heat dissipation target can be suppressed, thereby improving heat dissipation performance.

[0011] (2) In the above (1), it is preferable that the thermal contact portion of the heat-generating component contacts the heat dissipation target via an elastic heat conduction member when the heat-generating component is fixed to the heat dissipation target. By interposing the elastic heat conduction member between the thermal contact portion of the heat-generating component and the heat dissipation target, it is possible to absorb variations due to tolerances in the gap between the opposing surfaces of the heat-generating component and prevent the occurrence of a gap between the opposing surfaces, thereby further improving heat dissipation performance.

[0012] (3) In the above (1) or (2), it is preferable that the retaining portion includes a frame portion surrounding the periphery of the opening window and protruding into the case, and a retained portion protruding from the peripheral wall of the heat-generating component is placed on the protruding end surface of the frame portion. Because the retaining portion includes a frame portion surrounding the periphery of the opening window and protruding into the case, the frame portion can prevent the heat-generating component from interfering with other components. Furthermore, because the retained portion protruding from the peripheral wall of the heat-generating component is placed on the protruding end surface of the frame portion, the heat-generating component can be reliably prevented from jumping out of the opening window. This allows the heat-generating component to be stably held in the case during transportation of the circuit unit before being fixed to the fixed portion of the heat dissipation target.

[0013] (4) In the above (3), it is preferable that the holding portion includes a flexible piece portion that protrudes inward of the case beyond the frame body portion and is flexible and deformable toward the outer periphery of the opening window, the flexible piece portion has a locking claw portion provided at a protruding tip portion that protrudes toward the inner periphery of the opening window, the flexible piece portion allows the heat-generating component to be assembled to the frame body portion by being flexible and deformed toward the outer periphery, and when the held portion of the heat-generating component is placed on the protruding end surface of the frame body portion, the locking claw portion of the flexible piece portion that has elastically returned to its original state overlaps the heat-generating component with a gap in between in the protruding direction of the frame body portion. The holding portion further includes a flexible piece portion combined with the frame body portion, and the locking claw portion provided at the protruding tip portion of the flexible piece portion overlaps the heat-generating component with a held portion placed on the protruding end surface of the frame body portion with a gap in between in the protruding direction of the frame body portion. This not only prevents the heat-generating component from jumping out of the opening window, but also prevents it from moving in the opposite direction by engaging with the locking claw portion, making it possible to hold the heat-generating component more stably within the case.

[0014] (5) In the above (3) or (4), it is preferable that the fixing portion of the heat-generating component is located at the same position as the held portion in the protruding direction of the frame portion, and when fixed to the heat dissipation target, the fixed portion of the heat dissipation target is located inside the case beyond the protruding end face of the frame portion in the protruding direction of the frame portion. In the protruding direction of the frame portion, the fixing portion of the heat-generating component is located at the same position as the held portion placed on the protruding end face of the frame portion, and the fixed portion of the heat dissipation target is located inside the case beyond the protruding end face. Thus, by fixing the fixing portion to the fixed portion, the heat-generating component can be separated from the holding portion (frame portion), and the fixing portion of the heat-generating component can be directly fixed to the fixed portion of the heat dissipation target. As a result, reduction in heat dissipation performance due to tolerance overlap can be advantageously avoided or suppressed.

[0015] (6) In any one of (1) to (5) above, it is preferable that the case includes a lower case in which the opening window is provided and an upper case superimposed on the lower case, the opening window having a rectangular shape, the holding portion includes a protruding wall portion provided on each of a pair of opposing sides of the opening window and protruding inwardly of the case, a positioning wall portion provided on one of the other pair of opposing sides of the opening window and protruding inwardly of the case, and a displacement control rib provided on the upper case and arranged opposite the positioning wall portion with the heat-generating component sandwiched therebetween, the heat-generating component is positioned between the opposing surfaces of the positioning wall portion and the displacement control rib and between the opposing surfaces of the protruding wall portion, and a held portion protruding from a peripheral wall portion of the heat-generating component arranged between the protruding wall portions is placed on the protruding end surface of the protruding wall portion.

[0016] The heat-generating component can be easily positioned in a predetermined position by inserting it between the protruding walls relative to the lower case so that it slides toward the positioning wall from the side opposite the positioning wall and abuts against the positioning wall. Furthermore, by assembling the upper case, the heat-generating component can be positioned between the opposing surfaces of the positioning wall and the displacement-restricting rib and between the opposing surfaces of the protruding wall. In addition, the retained portion protruding from the peripheral wall of the heat-generating component positioned between the protruding wall portions rests on the protruding end surface of the protruding wall, reliably preventing the heat-generating component from jumping out of the opening. This allows the heat-generating component to be stably retained within the case, even during transportation of the circuit unit before being fixed to the fixed portion of the heat dissipation target.

[0017] (7) In the above (6), it is preferable that the holding portion includes a displacement restricting piece that extends from the protruding tip of the positioning wall portion toward the heat-generating component, is located inside the case relative to the protruding end face of the protruding wall portion, and is arranged facing the heat-generating component across a gap. The protruding tip of the positioning wall portion is provided with a displacement restricting piece that is located inside the case relative to the protruding end face of the protruding wall portion and faces the heat-generating component across a gap. This makes it possible to restrict not only the heat-generating component from protruding out of the opening window but also its displacement in the opposite direction by engagement with the displacement restricting piece, thereby more stably holding the heat-generating component within the case.

[0018] (8) In the above (6) or (7), it is preferable that the fixing portion of the heat-generating component is located at the same position as the held portion in the protruding direction of the protruding wall portion, and when fixed to the heat dissipation target, the fixed portion of the heat dissipation target is located inside the case beyond the protruding end face in the protruding direction of the protruding wall portion. In the protruding direction of the protruding wall portion, the fixing portion of the heat-generating component is located at the same position as the held portion placed on the protruding end face of the protruding wall portion, and the fixed portion of the heat dissipation target is located inside the case beyond the protruding end face. Thus, by fixing the fixing portion to the fixed portion, the heat-generating component can be separated from the holding portion (protruding wall portion), and the fixing portion of the heat-generating component can be directly fixed to the fixed portion of the heat dissipation target. As a result, reduction in heat dissipation performance due to tolerance overlap can be advantageously avoided or suppressed.

[0019] <Details of Embodiments of the Present Disclosure> Specific examples of the circuit unit 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 equivalent to the claims.

[0020] First Embodiment A circuit unit 10 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 9 . The circuit unit 10 is mounted, for example, on an electric vehicle or a hybrid vehicle and connected between an on-board power source (e.g., a battery) (not shown) and a load (e.g., an inverter) (not shown). Note that the circuit unit 10 can be positioned in any orientation within the vehicle; however, in the following description, the upper side will be referred to as the upper side in FIG. 4 , the lower side as the lower side in FIG. 4 , the left side as the left side in FIG. 3 , the right side as the right side in FIG. 3 , the front side as the lower side in FIG. 3 , and the rear side as the upper side in FIG. 3 . Furthermore, in some cases, when multiple identical components are illustrated, only some of the components will be designated by reference numerals, and the reference numerals will be omitted for the other components.

[0021] <Circuit Unit 10> The circuit unit 10 includes a heat-generating component having a thermal contact portion 14 that is in thermal contact with a heat dissipation target (a housing 12, described below) and a fixing portion 16 that is fixed to the heat dissipation target (the housing 12). The circuit unit 10 of the first embodiment includes a relay 18, a precharge relay 20, and a precharge resistor 22 as electrical components that generate heat when energized. However, in the first embodiment, the structure of the present disclosure is applied to the precharge resistor 22, one of the electrical components, and therefore the heat-generating component is constituted by the precharge resistor 22. The circuit unit 10 also includes a case 24 that holds the heat-generating component (the precharge resistor 22). In the first embodiment, the case 24 accommodates and holds not only the precharge resistor 22 but also the relay 18 and the precharge relay 20.

[0022] Furthermore, the circuit unit 10 includes a holding portion 26 that protrudes into the inside of the case 24 and holds the heat-generating component (pre-charge resistor 22) within the case 24, an opening window 28 that penetrates the case 24 and exposes the thermal contact portion 14 of the heat-generating component (pre-charge resistor 22) to the outside of the case 24, and an insertion hole 30 that penetrates the case 24 and into which a fixed portion 42 (described later) that is provided on the heat dissipation target (housing 12) is inserted.

[0023] <Heat Dissipation Target (Housing 12)> The circuit unit 10 and the battery constituting the on-board power supply may be housed in, for example, a metal housing 12. The housing 12 houses the circuit unit 10 and the battery to form a battery pack (not shown). That is, the circuit unit 10 is fixed on top of and stacked on the top surface 32 of the housing 12, and heat generated by energizing electrical components provided within the circuit unit 10 is dissipated through the housing 12. Therefore, in the first embodiment, the metal housing 12 serves as a heat dissipation target for dissipating heat generated by the circuit unit 10. Note that the figure shows a flat metal plate constituting the bottom wall of the housing 12. As shown in FIG. 1 , for example, a refrigerant flow path 34 may be formed within this metal plate. A known refrigerant may be used as the refrigerant flowing through the refrigerant flow path 34. The extension direction and length of the refrigerant flow path 34 shown in FIG. 1 are merely exemplary, and the extension direction and length of the refrigerant flow path are not limited.

[0024] 6 , the upper surface 32 of the housing 12 is provided with upwardly protruding support portions 36 at four locations around the fixed position of the circuit unit 10, supporting the four corners of the circuit unit 10. A bolt fastening hole 40 is formed at the center of each support portion 36, opening upward, into which a bolt 38 for fastening the circuit unit 10 is fastened. Furthermore, the upper surface 32 of the housing 12 is provided with a protruding fixed portion 42 at a predetermined location around the fixed position of the circuit unit 10, to which the fixed portion 16 of the heat-generating component (pre-charge resistor 22) is fastened. In the first embodiment, the two fixed portions 42 are provided at a predetermined distance in the front-to-rear direction, and each fixed portion 42 has a predetermined protruding dimension. In particular, in the first embodiment, each fixed portion 42 is generally prismatic, and a screw fastening hole 46 is formed at the upper end of each fixed portion 42, into which a screw 44 is fastened to fasten each fixed portion 42 to each other.

[0025] <Relays 18> In the first embodiment, a pair of relays 18, 18 are provided in the circuit unit 10 and are arranged spaced apart from each other in the left-right direction. One relay (the right relay in the first embodiment) is a positive relay 18a, and the other relay (the left relay in the first embodiment) is a negative relay 18b. The positive and negative relays 18a, 18b each have a pair of terminals 48, 48 (one of which is shown in FIG. 4 ) on their front sides (the positive relay 18a is at the front, and the negative relay 18b is at the rear) that are spaced apart from each other in the left-right direction, and each terminal 48 is exposed on the surface of each relay 18a, 18b.

[0026] The terminals 48 are input and output terminals for the relays 18a, 18b, and for example, in the positive relay 18a, the left terminal 48 is an input terminal on the positive side, and the right terminal 48 is an output terminal on the positive side. In addition, in the negative relay 18b, the left terminal 48 is an output terminal on the negative side, and the right terminal 48 is an input terminal on the negative side.

[0027] An energization bus bar 50 is overlapped with each terminal portion 48 of each of the relays 18a, 18b and fixed with a bolt 52. That is, the circuit unit 10 includes first and second energization bus bars 50a, 50b connected to the input and output terminal portions 48, 48 of the positive-side relay 18a, and third and fourth energization bus bars 50c, 50d connected to the input and output terminal portions 48, 48 of the negative-side relay 18b. When the circuit unit 10 is assembled, the ends of the first to fourth energization bus bars 50a-50d are exposed to the outside through through windows 106a-106d provided in an upper case 98 of the case 24 (described later), and form input and output connection portions 54a, 54b on the positive side and input and output connection portions 54c, 54d on the negative side, respectively.

[0028] The input connection portion 54a on the positive side and the input connection portion 54c on the negative side are electrically connected to the positive and negative terminal portions of a battery (not shown) by conductive members such as bus bars or electric wires. The output connection portion 54b on the positive side and the output connection portion 54d on the negative side are electrically connected to the positive and negative terminal portions of an inverter (not shown) by conductive members. Each of these connections 54a to 54d and the conductive members can be fixed with a bolt 56.

[0029] Thus, the relays 18a, 18b, the first to fourth current-carrying bus bars 50a to 50d, and the above-described conductive members form a main circuit 58 between the battery and the inverter. By switching the relays 18a, 18b between ON and OFF in the main circuit 58, the main circuit 58 between the battery and the inverter can be switched between a conducting state and a non-conducting state.

[0030] In addition to the first to fourth current-carrying bus bars 50a to 50d, first to fourth heat-dissipating bus bars 60a to 60d are fastened to the terminals 48 of the positive and negative relays 18a, 18b by bolts 52. Each of the first to fourth heat-dissipating bus bars 60a to 60d is generally L-shaped and has a portion that extends in the vertical direction and a portion that bends from the lower end of the vertically extending portion and expands in the horizontal direction (a direction perpendicular to the vertical direction). The upper ends of the heat-dissipating bus bars 60a to 60d are fixed to the terminals 48 of the relays 18a, 18b by bolts 52, and their lower ends extend in the front-rear direction and are located below the relays 18a, 18b.

[0031] A heat dissipation section 62 is formed by a portion extending in the front-rear direction at the lower end of each of the heat dissipation bus bars 60a-60d, and each heat dissipation section 62 is in thermal contact with the housing 12, which is the heat dissipation target, via an insulating sheet 64 and an elastic heat-conducting member 66. Known materials may be used for the insulating sheet 64 and the elastic heat-conducting member 66, and in particular, a heat-conducting sheet or gap filler having good thermal conductivity may be used for the elastic heat-conducting member 66. With this structure, each terminal section 48 of each relay 18a, 18b is in thermal contact with the housing 12 via each of the heat dissipation bus bars 60a-60d, the insulating sheet 64, and the elastic heat-conducting member 66, and heat generated when current is applied to each relay 18a, 18b can be dissipated from the housing 12.

[0032] <Precharge Circuit 68> A precharge circuit 68 is connected in parallel to the positive relay 18a in the main circuit 58. Specifically, in the precharge circuit 68, a precharge relay 20 and a precharge resistor 22 are connected in series. The precharge relay 20 and the input terminal 48 of the positive relay 18a are electrically connected by an electric wire 70, and the precharge resistor 22 and the output terminal 48 of the positive relay 18a are electrically connected by an electric wire 72. The precharge relay 20 and the precharge resistor 22 are also electrically connected by an electric wire 74.

[0033] A terminal 76 is provided on at least one end of each of the electric wires 70, 72, 74, and each terminal 76 is overlapped with each terminal portion 48 of the positive side relay 18a or each terminal portion 80 (described later) of the precharge relay 20, and fixed by a bolt 52 or a screw 78.

[0034] <Pre-charge relay 20> A known pre-charge relay 20 may be used, and its structure is not limited thereto. However, it includes a pair of terminals 80, 80 (one of which is shown in FIG. 4 ) spaced apart from each other in the left-right direction. In the first embodiment, the pre-charge relay 20 is positioned with its upper front facing upward, and each terminal 80 is exposed on the top surface of the pre-charge relay 20. A terminal 76 provided at the end of an electric wire 70 connecting the positive relay 18a and the pre-charge relay 20 is overlapped with an input terminal 80 (left terminal 80) of the pre-charge relay 20 and fixed with a screw 78. Furthermore, a terminal 76 provided at the end of an electric wire 74 connecting the pre-charge relay 20 and the pre-charge resistor 22 is overlapped with an output terminal 80 (right terminal 80) of the pre-charge relay 20 and fixed with a screw 78.

[0035] <Precharge Resistor 22> The precharge resistor 22 is configured using a metal-clad resistor. Because a known type of precharge resistor (metal-clad resistor) can be used, detailed description will be omitted. The precharge resistor 22 is configured by sealing a wire-wound resistor (not shown) in an insulated state in a metal case 82. Note that in cross-sectional views such as FIG. 5 , the internal structure of the precharge resistor 22 is omitted, and only the metal case 82 is shown. In other words, the metal case 82 of the precharge resistor 22 is hollow, and a wire-wound resistor (not shown) is housed inside the metal case 82 in an insulated state. In embodiment 1, the metal case 82 of the precharge resistor 22 is hollow and approximately rectangular and extends in the front-to-rear direction. That is, the metal case 82 is configured to include a substantially cylindrical peripheral wall 84 including wall portions on both front-to-rear and left-to-right sides, an upper wall 86 covering an upper opening of the peripheral wall 84, and a lower wall 88 covering a lower opening of the peripheral wall 84.

[0036] In particular, in the first embodiment, flange-like portions 90 are provided on both front-rear directions of the upper end portion (or upper wall portion 86) of the peripheral wall portion 84 of the metal case 82. Each of these flange-like portions 90 has a widthwise (left-right) dimension that is approximately equal to that of the upper wall portion 86 (or peripheral wall portion 84) and a predetermined protruding dimension (front-rear dimension), and a screw insertion groove 92 is provided in the left-right central portion of each flange-like portion 90, through which the above-mentioned screw 44 that secures the pre-charge resistor 22 is inserted. Due to the provision of each flange-like portion 90, the upper surface 93a of the pre-charge resistor 22 (the upper surface of the upper wall portion 86) has a larger area than the lower surface 93b of the pre-charge resistor 22 (the lower surface of the lower wall portion 88) when projected in the vertical direction.

[0037] As described below, each flange-shaped portion 90 is overlapped with each fixed portion 42 of the housing 12, and each screw 44 is inserted into the screw insertion groove 92 and fastened to the screw fastening hole 46, thereby fixing the fixing portion 16 of the heat-generating component (pre-charge resistor 22) to the fixed portion 42. Therefore, the portion of each flange-shaped portion 90 surrounding the screw insertion groove 92 (the left-right central portion of each flange-shaped portion 90) forms the fixing portion 16. Furthermore, both left-right end portions of each flange-shaped portion 90 are placed on holding portions 26 that protrude into the inside of the case 24 (the lower case 100 described below), thereby holding the heat-generating component (pre-charge resistor 22) within the case 24. Therefore, both left-right end portions of each flange-shaped portion 90 form held portions 94. As a result, in the first embodiment, each fixing portion 16 and each held portion 94 are provided on each flange-shaped portion 90, i.e., are provided at the same vertical position.

[0038] As described above, the pre-charge resistor 22 is connected to the electric wire 72 connected to the positive relay 18a and the electric wire 74 connected to the pre-charge relay 20. Specifically, the electric wire 72 is connected to one end of a winding provided inside the pre-charge resistor 22, and the electric wire 74 is connected to the other end. The electric wires 72, 74 connected to both ends of the winding extend from the inside of the metal case 82 to the outside. In the first embodiment, the electric wires 72, 74 extend to the outside from one end in the longitudinal direction of the metal case 82 (the front end in the first embodiment). The terminals 76 provided at the ends of the electric wires 72, 74 are overlapped with the output terminal portion 48 of the positive relay 18a and the output terminal portion 80 of the pre-charge relay 20, respectively, and are fixed by the bolts 52 and the screws 78, respectively.

[0039] The metal case 82 of this precharge resistor 22 (metal-clad resistor) has a thermal contact portion 14 that is in thermal contact with the housing 12, which is the heat dissipation target. In the first embodiment, when the circuit unit 10 described below is fixed to the housing 12, the metal case 82 is overlapped with the housing 12 via an elastic heat-conducting member 96 provided on the lower surface 93b, and the thermal contact portion 14 is formed by the lower wall portion 88 that constitutes the hollow metal case 82. The elastic heat-conducting member 96 may be made of the same material as the elastic heat-conducting members 66 provided below the relays 18a and 18b. Note that these elastic heat-conducting members 66 and 96 may initially be rectangular sheets, or may be initially in a gel or grease-like form that hardens into a sheet shape upon exposure to heat or light.

[0040] <Case 24> As described above, the circuit unit 10 includes a case 24 that holds the relays 18a, 18b, the pre-charge relay 20, and the pre-charge resistor 22. In the first embodiment, the case 24 has a hollow rectangular parallelepiped shape overall, with the left-right dimension being larger than the front-rear dimension. In particular, in the first embodiment, the case 24 includes an upper case 98 and a lower case 100 that can be assembled and disassembled relative to each other in the vertical direction. The upper case 98 and the lower case 100 are formed, for example, from a synthetic resin. While the method for fastening the upper case 98 and the lower case 100 is not limited, in the first embodiment, the upper case 98 and the lower case 100 are fastened to each other by inserting the bolts 38 described above into the four corners of the circuit unit 10 and fastening them to the bolt fastening holes 40 provided in each support portion 36 of the housing 12 with the upper case 98 and the lower case 100 overlapping each other.

[0041] The upper case 98 has a generally box-like shape that opens downward, and includes an upper bottom wall 102 and an upper peripheral wall 104 that protrudes downward from the outer periphery of the upper bottom wall 102. Rectangular through-windows 106a to 106d that penetrate the upper bottom wall 102 in the thickness direction (vertical direction) are provided at positions corresponding to the connection portions 54a to 54d of the first to fourth current-carrying bus bars 50a to 50d when the circuit unit 10 is assembled. Mounting portions 110 with bolt insertion holes 108 are provided at the four corners of the periphery of the upper case 98, and each mounting portion 110 is located somewhat above the lower end of the upper peripheral wall 104. In addition, in the upper bottom wall portion 102, circular insertion holes 112 that penetrate in the thickness direction are provided at positions corresponding to each insertion hole 30 of the lower case 100 when the circuit unit 10 is assembled, and each screw 44 is tightened from above through each insertion hole 112 into the bolt fastening hole 40 in each fixed portion 42.

[0042] 7 and other figures, the lower case 100 has a bottom wall 114 that is generally flat, and the bottom wall 114 has substantially the same rectangular shape in plan view as the upper case 98. As a result, when the upper case 98 and the lower case 100 are overlapped and fixed together, the bottom wall 114 of the lower case 100 covers the lower opening of the upper case 98.

[0043] The bottom wall 114 has rectangular openings 116 penetrating in the thickness direction (vertical direction) at positions corresponding to the heat dissipation portions 62 of the first to fourth heat dissipation bus bars 60a to 60d when the circuit unit 10 is assembled. The bottom wall 114 also has the aforementioned openings 28 penetrating in the thickness direction (vertical direction) at positions corresponding to the thermal contact portions 14 (lower wall portions 88 of the metal case 82) of the pre-charge resistors 22 (metal-clad resistors) when the circuit unit 10 is assembled. In the first embodiment, the openings 28 are rectangular and have a larger area than the lower surface 93b of the pre-charge resistors 22 in a plan view. This allows the openings 28 to expose the thermal contact portions 14 (lower wall portions 88) of the metal case 82 so that they can be in thermal contact with the housing 12 when the circuit unit 10 is assembled. Furthermore, the aforementioned insertion holes 30 into which the respective fixed portions 42 of the housing 12 are inserted are formed on both front and rear sides of the opening window 28. Each of these insertion holes 30 has a substantially rectangular shape. In the first embodiment, the opening window 28 and each insertion hole 30 are in communication with each other, and each insertion hole 30 is formed so as to be connected to each other on both front and rear sides of the inner peripheral surface of the opening window 28.

[0044] In the first embodiment, an insulating sheet 64 and an elastic heat-conducting member 66 are stacked and housed in each opening window 116 provided below each heat dissipation portion 62. This allows each heat dissipation portion 62 of the first to fourth heat dissipation bus bars 60a to 60d to be in electrically insulated and thermally conductive contact with the housing 12, which is placed on the bottom wall portion 114. The insulating sheet 64 and the elastic heat-conducting member 66 do not need to be separate members, but may be formed from a single member having insulating and thermally conductive properties. The insulating sheet 64 and the elastic heat-conducting member 66 are fixed (e.g., glued) to the lower surface of each heat dissipation portion 62, for example, when the circuit unit 10 is fixed to the housing 12. As shown in FIG. 4 , when the circuit unit 10 is fixed to the housing 12, each insulating sheet 64 and each elastic heat-conducting member 66 are housed and disposed within each opening window 116.

[0045] Furthermore, an elastic heat-conducting member 96 is housed in the opening 28 provided below the thermal contact portion 14 of the pre-charge resistor 22. This allows the thermal contact portion 14 to be in thermally conductive contact with the housing 12. Because the wire-wound resistor constituting the pre-charge resistor 22 is housed in the metal case 82 in an insulated state, the metal case 82 remains electrically insulated even when the circuit unit 10 is energized, and the insulating sheet 64 does not need to be placed in the opening 28. The elastic heat-conducting member 96 is fixed (e.g., glued) to the lower surface 93 b of the thermal contact portion 14 (the lower wall portion 88 of the metal case 82) when the circuit unit 10 is fixed to the housing 12. When the circuit unit 10 is fixed to the housing 12, the elastic heat-conducting member 96 is housed and positioned inside the opening 28.

[0046] Furthermore, mounting portions 120 having bolt insertion holes 118 are provided at the four corners of the periphery of the lower case 100 (bottom wall portion 114), and each mounting portion 120 is positioned somewhat higher than the remaining portions of the bottom wall portion 114. In other words, recesses that are recessed upward relative to the remaining portions are formed at the four corners of the periphery of the underside 121 of the lower case 100. In this way, the mounting portions 110, 120 are formed at the four corners of the periphery of the upper case 98 and the outer periphery of the lower case 100, thereby providing corresponding concave and convex shapes. As a result, when the upper case 98 and the lower case 100 are stacked vertically, these concave and convex shapes fit together, allowing the upper case 98 and the lower case 100 to be positioned relative to each other in the horizontal direction.

[0047] <Retaining Portion 26> The lower case 100 further includes the aforementioned retaining portion 26, which includes a frame portion 122 that surrounds the window 28 and protrudes upward toward the inside of the case 24. That is, the frame portion 122 protrudes vertically (particularly, from bottom to top). Specifically, the frame portion 122 has a pair of side walls 124, 124 that extend in the front-rear direction at both left and right edges of the window 28. Each side wall 124 has a larger front-rear dimension than the window 28. Both front-rear end portions of each side wall 124 are bent in a crank shape, and the both front-rear end portions of each side wall 124 are located laterally inward of the intermediate portion via a bent portion 126. The both front-rear end portions of each side wall 124 form mounting portions 128 on which the flange-shaped portions 90 of the metal case 82 of the pre-charge resistor 22 are mounted.

[0048] Each mounting portion 128 is located outward in the front-rear direction from the opening window 28, and in the first embodiment, since each insertion hole 30 is formed to be connected to both front-rear end portions of the opening window 28, each mounting portion 128 is provided on both left and right sides of each insertion hole 30. In other words, at both front-rear end portions of the frame body portion 122, insertion windows 129 that penetrate in the front-rear direction are provided between opposing mounting portions 128, and each insertion window 129 connects the inside and outside of the frame body portion 122 to each other. In the first embodiment, two electric wires 72, 74 extend from the front end of the precharge resistor 22, and when the precharge resistor 22 is held by the frame body portion 122 (holding portion 26), each of the electric wires 72, 74 extends to the outside through the front insertion window portion 129. However, depending on the wiring configuration of the precharge circuit 68, each of the electric wires 72, 74 may also extend to the outside through the rear insertion window portion 129.

[0049] More specifically, each flange-shaped portion 90 (particularly the retained portion 94, which is the both left-right end portion) of the metal case 82 is placed on both front-to-rear end portions of the protruding end surface (upper end surface) 130 of the frame body portion 122, i.e., the protruding end surface 130 of each mounting portion 128.

[0050] Here, the upward protrusion dimension A (the vertical dimension from the upper surface of the bottom wall portion 114 to the protruding end face 130) of the frame portion 122 (see FIG. 9 ) is smaller than the upward protrusion dimension B (the vertical dimension from the upper surface 32 of the housing 12 to the upper surface of each fixed portion 42) of each fixed portion 42 provided on the housing 12 (see FIG. 5 ). In particular, as will be described later, when the circuit unit 10 is fixed to the housing 12, each fixed portion 42 protrudes into the circuit unit 10 through each insertion hole 30 of the lower case 100, and each fixed portion 42 is positioned inside (above) the case 24 beyond the protruding end face 130 in the protruding direction (vertical direction) of the frame portion 122. In other words, when the circuit unit 10 is fixed to the housing 12, the upper surface of each fixed portion 42 is positioned above the protruding end face 130 of the frame portion 122.

[0051] <Flexible Pieces 132> The holding portion 26 also includes flexible pieces 132 that protrude upward, more inward of the case 24 than the frame portion 122, and are capable of flexible deformation (elastic deformation in the first embodiment) toward the outer periphery of the opening window 28. In the first embodiment, the flexible pieces 132 are provided in a middle portion in the front-rear direction of each side wall portion 124, and particularly in the first embodiment, a pair of flexible pieces 132, 132 are provided spaced apart from each other in the front-rear direction in the middle portion in the front-rear direction of each side wall portion 124. Therefore, in the first embodiment, a total of four flexible pieces 132 are provided in the holding portion 26.

[0052] Each flexible piece 132 has a locking claw 134 that is provided at its protruding tip (upper end) and protrudes toward the inner periphery (inward in the left-right direction) of the opening window 28. Each locking claw 134 protrudes inward in the left-right direction to a position where it overlaps in the up-down direction with the upper wall portion 86 of the precharge resistor 22 (metal case 82) when the precharge resistor 22 is assembled to the lower case 100. In other words, when the precharge resistor 22 is assembled to the lower case 100, the protruding tip (inner end in the left-right direction) of each locking claw 134 overlaps with both left and right side edges of the upper wall portion 86 in a plan view.

[0053] The upper surface of each locking claw 134 is provided with an inclined surface 136 that gradually slopes downward as it extends inward in the left-right direction. As a result, when the pre-charge resistor 22 is assembled to the holding portion 26, the pre-charge resistor 22 is brought close to the holding portion 26 from above, causing both left-right edge portions of the lower surface 93b of the metal case 82 to abut against the inclined surfaces 136 of each locking claw 134, elastically deforming each flexible piece 132 outward in the left-right direction. This allows the pre-charge resistor 22 to be assembled to the frame body 122. Furthermore, when each flange-shaped portion 90 of the metal case 82 is placed on the protruding end surface 130 of each mounting portion 128, each flexible piece 132 elastically restores its original deformation (elastic recovery), so that, as shown in Figure 9, etc., the locking claw portion 134 of each flexible piece 132 overlaps the pre-charge resistor 22 with a gap 138 in the protruding direction (vertical direction) of the frame body portion 122.

[0054] <Assembly of Circuit Unit 10> A specific example of a method for assembling the circuit unit 10 will now be described. Note that the method for assembling the circuit unit 10 is not limited to the embodiment described below.

[0055] First, the first to fourth current-carrying bus bars 50a to 50d and the first to fourth heat-dissipating bus bars 60a to 60d are placed on the terminal portions 48 of the relays 18a, 18b, respectively, and are then secured with the bolts 52. At this time, the terminals 76 provided at the ends of the electric wires 70, 72 are also placed on the terminal portions 48 of the positive-side relay 18a, and are then fastened together with the bolts 52. Then, the relays 18a, 18b and the pre-charge relay 20 are placed on the lower case 100 and secured with bolts or screws.

[0056] The precharge resistor 22 is then brought close to the retaining portion 26 of the lower case 100 from above, and assembled while elastically deforming the flexible pieces 132 outward in the left-right direction. The locking claws 134 of each flexible piece 132 climb over the upper wall portion 86 of the metal case 82, causing each flexible piece 132 to elastically restore its original shape. As a result, the flange-like portions 90 of the metal case 82 are placed on the protruding end surfaces 130 of the mounting portions 128 of the retaining portion 26, and the retained portions 94 at both left and right ends of each flange-like portion 90 are held by the retaining portion 26. In this state, the inner left-right ends of each locking claw 134 overlap the left and right side edges of the upper wall portion 86 in the up-down direction. Therefore, even if the precharge resistor 22 is displaced upward, the engagement between the locking claws 134 and the upper wall portion 86 prevents the precharge resistor 22 from slipping out of the retaining portion 26. In other words, in this state, the precharge resistors 22 are movable up and down within the gaps 138 and are temporarily assembled to the lower case 100 .

[0057] Next, as shown in FIG. 8 , the upper case 98 is brought close from above to the lower case 100, in which the relays 18 a, 18 b, the pre-charge relay 20, and the pre-charge resistor 22 have been assembled as described above, and the upper case 98 and the lower case 100 are then overlapped as shown in FIG. 9 . This causes the mounting portions 110 of the upper case 98 to overlap the mounting portions 120 of the lower case 100, and the concave and convex shapes on the outer peripheries of the upper case 98 and the lower case 100 fit together as described above. As a result, horizontal misalignment of the upper case 98 and the lower case 100 is prevented, and the circuit unit 10 of the first embodiment is completed. Note that, before the circuit unit 10 is assembled into the housing 12, the upper case 98 and the lower case 100 may be prevented from being separated from each other in the vertical direction by, for example, inserting bolts 38 into the bolt insertion holes 108, 118 at the four corners.

[0058] <Assembly of Circuit Unit 10 to Heat Dissipation Target (Housing 12)> A specific example of a method for assembling the circuit unit 10 to the housing 12, which is the heat dissipation target, will be described below. Note that the method for assembling the circuit unit 10 to the housing 12 is not limited to the embodiment described below.

[0059] First, the circuit unit 10 manufactured as described above is placed on a predetermined position on the top surface 32 of the housing 12. For ease of understanding, although Figures 2 and 3 show the upper case 98 separated from the lower case 100, the circuit unit 10 is assembled to the housing 12 as a whole. At this time, the insulating sheets 64 and the elastic heat-conducting members 66 are laminated and fixed to the heat-dissipating portions 62 of the heat-dissipating bus bars 60a to 60d, and the elastic heat-conducting member 96 is fixed to the lower wall portion 88 of the pre-charge resistor 22 (metal case 82). The circuit unit 10 is placed on the top surface 32 of the housing 12 so that the support portions 36 protruding above the top surface 32 fit into recesses formed by providing the mounting portions 120 on the bottom surface of the circuit unit 10 (the bottom surface 121 of the lower case 100). This positions the circuit unit 10 and the housing 12 in the horizontal direction, and vertically connects the bolt insertion holes 108, 118 at the four corners of the circuit unit 10 with the bolt fastening holes 40 in the support portions 36.

[0060] Then, by placing the circuit unit 10 on the upper surface 32 of the housing 12, the fixed portions 42 protruding upward from the upper surface 32 are inserted into the circuit unit 10 through the insertion holes 30 provided in the lower case 100. In particular, as described above, when the lower surface of the circuit unit 10 (the lower surface 121 of the lower case 100) and the upper surface 32 of the housing 12 are placed together, the upper surfaces of the fixed portions 42 protrude upward beyond the protruding end surfaces 130 of the frame portions 122. As a result, when the lower surface 121 of the circuit unit 10 and the upper surface 32 of the housing 12 are placed together, the upper surfaces of the fixed portions 42 abut against the flange portions 90 of the metal cases 82 from below, and the flange portions 90 (particularly the held portions 94) are spaced upward from the protruding end surfaces 130 of the holding portions 26 (particularly the mounting portions 128). As a result, the screw insertion grooves 92 in each flange-shaped portion 90 and the screw fastening holes 46 in each fixed portion 42 communicate with each other in the vertical direction.

[0061] In this state, bolts 38 are inserted into the bolt insertion holes 108, 118 at the four corners of the circuit unit 10 and fastened to the bolt fastening holes 40. Furthermore, screws 44 are inserted into the screw insertion grooves 92 through the insertion holes 112 in the upper case 98 and fastened to the screw fastening holes 46, thereby fixing the fixing portions 16 formed around the screw insertion grooves 92 to the fixed portions 42. This completes the assembly of the circuit unit 10 to the housing 12. With the circuit unit 10 assembled in the housing 12, the heat dissipation portions 62 of the heat dissipation bus bars 60a-60d are in thermal contact with the housing 12 via the insulating sheets 64 and the elastic heat conductive members 66, and the thermal contact portion 14 of the pre-charge resistor 22 is in thermal contact with the housing 12 via the elastic heat conductive member 96. When the circuit unit 10 is assembled in the housing 12, it is preferable that each of these insulating sheets 64 and each of the elastic heat conduction members 66, 96 be slightly compressed in the vertical direction between each of the heat dissipation sections 62 and the thermal contact section 14 (lower wall section 88) and the housing 12.

[0062] As described above, the circuit unit 10 assembled inside the battery pack housing 12 has the connection portions 54a to 54d electrically connected to the battery and the inverter by conductive members (not shown), thereby electrically connecting the battery and the inverter via the circuit unit 10.

[0063] Generally, when a vehicle is started, electricity flows from the battery to the inverter to charge the capacitor in the inverter. However, the current (inrush current) generated during vehicle startup is relatively large, and if the inrush current flows through the main circuit, it may damage the main relay. To prevent this damage, a pre-charge resistor is provided. Specifically, when the vehicle is started, the positive relay 18a is turned OFF and the pre-charge relay 20 is turned ON, thereby supplying power from the battery to the capacitor in the inverter via the pre-charge circuit 68, preventing damage to the positive relay 18a and charging the capacitor. After the vehicle is started, the positive relay 18a is turned ON and the pre-charge relay 20 is turned OFF, thereby supplying power from the battery to the inverter through the main circuit 58. Therefore, when the pre-charge circuit 68 is energized during vehicle startup, the pre-charge resistor 22 generates heat, and when the main circuit 58 is energized after the vehicle is started, the relays 18a and 18b generate heat. That is, the precharge resistor 22 and the positive relay 18a generate heat at different times.

[0064] On the other hand, the housing 12, with which the thermal contact portion 14 is in thermal contact, is also in thermal contact with the positive relay 18a. This allows a common heat dissipation path to be configured for the pre-charge resistor 22 and the positive relay 18a, which generate heat at different times, and avoids an increase in the number of parts compared to when separate heat dissipation paths are configured for the pre-charge resistor 22 and the positive relay 18a.

[0065] In the circuit unit 10 of embodiment 1 having the above-described structure, a metal-clad resistor capable of handling large currents is employed as the pre-charge resistor 22. That is, the metal-clad resistor is an insulated wire-wound resistor housed in a metal case 82, and heat can be dissipated through the metal case 82. As a result, the metal-clad resistor has better heat dissipation properties than, for example, a ceramic resistor, and even when multiple ceramic resistors are required, a smaller number of metal-clad resistors (for example, one) can handle large currents. As a result, the mounting space for the pre-charge resistor can be reduced, allowing the circuit unit 10 to be made more compact.

[0066] In particular, in circuit unit 10, before mounting to housing 12, which is the heat dissipation target, pre-charge resistor 22, which is a heat-generating component, is held by holding portion 26 provided on case 24 within case 24, but when mounted to housing 12, pre-charge resistor 22 is separated from holding portion 26, and each fixing portion 16 of pre-charge resistor 22 is fixed directly to each fixed portion 42 of housing 12. This eliminates the need to consider tolerances in case 24, and allows for more reliable thermal contact between thermal contact portion 14 of pre-charge resistor 22 and housing 12.

[0067] Specifically, an elastic heat-conducting member 96 is provided between the thermal contact portion 14 and the housing 12. This prevents an air gap from being interposed between the thermal contact portion 14 and the housing 12, improving heat dissipation efficiency. Furthermore, in a conventional structure in which the precharge resistor is fixed to a case and the case is fixed to the housing to provide thermal contact between the precharge resistor and the housing, it is necessary to consider the tolerance of the case, and therefore the elastic heat-conducting member must be made thick. In other words, by directly fixing the precharge resistor 22 to the housing 12 as in the first embodiment, it is not necessary to consider the tolerance of the case 24, and therefore the elastic heat-conducting member 96 can be made thin, improving heat conduction efficiency.

[0068] The retaining portion 26 includes a frame portion 122 that surrounds the periphery of the opening window 28 and protrudes inwardly into the case 24. Before the circuit unit 10 is fixed to the housing 12, a retained portion 94 (flange-shaped portion 90) of the precharge resistor 22 that protrudes outward from the peripheral wall portion 84 is placed against a protruding end surface 130 of the frame portion 122. This prevents the precharge resistor 22 from being removed from the circuit unit 10 through the opening window 28. In particular, in the first embodiment, the frame portion 122 includes a pair of side walls 124, 124 that face each other in the left-right direction. When the precharge resistor 22 is held by the retaining portion 26, left-right displacement of the precharge resistor 22 is also suppressed. As a result, displacement of the precharge resistor 22 within the case 24 is suppressed before the circuit unit 10 is fixed to the housing 12, and damage to the precharge resistor 22 can be prevented.

[0069] Furthermore, the holding portion 26 includes a flexible piece 132 having a locking claw 134 at its protruding tip, and when the precharge resistor 22 is assembled to the holding portion 26, the locking claws 134 come into contact with the upper wall 86 of the metal case 82, preventing the precharge resistor 22 from being pulled out upward from the holding portion 26. Therefore, before the circuit unit 10 is fixed to the housing 12, not only is left-right displacement suppressed as described above, but upward displacement is also suppressed, so that damage to the precharge resistor 22 can be more reliably prevented.

[0070] The fixing portions 16 of the precharge resistor 22 are located at the same vertical position as the retained portions 94, and the retained portions 42 of the housing 12 are positioned higher, beyond the protruding end surface 130 of the frame portion 122, when the circuit unit 10 is fixed to the housing 12. In the first embodiment, the fixing portions 16 and retained portions 94 of the precharge resistor 22 are both formed on the flange-shaped portions 90 of the metal case 82. This allows the precharge resistor 22 and, ultimately, the circuit unit 10 to be manufactured with a simpler structure than, for example, when the fixing portions and retained portions are provided separately. Furthermore, the fixing portions 42 protrude upward from the top surface 32 of the housing 12, and a screw fastening hole 46 is provided at the upper end of each fixing portion 42. This allows the refrigerant flow path 34 to be formed in the housing 12 without considering the position of the screw fastening holes 46.

[0071] Second Embodiment Next, a circuit unit 140 according to a second embodiment of the present disclosure will be described with reference to Figures 10 to 16. The basic structure of the circuit unit 140 according to the second embodiment is the same as that of the first embodiment, and the configurations of the main circuit 58 and the precharge circuit 68 are the same as those of the first embodiment. However, the circuit unit 140 according to the second embodiment differs from the first embodiment in the manner in which the precharge resistor 22 is held by the holding portion 142 before being fixed to the housing 12. Below, differences from the first embodiment will be mainly described, and the same members and parts as those in the first embodiment will be denoted in the figures with the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

[0072] <Case 144> The circuit unit 140 of the second embodiment also has a case 144 that holds the relays 18a, 18b, the pre-charge relay 20, and the pre-charge resistor 22, and this case 144 is configured to include an upper case 146 and a lower case 148. The upper case 146 and the lower case 148 are overlapped and fixed to each other.

[0073] <Upper Case 146> The upper case 146 has the same overall shape as the upper case 98 in the first embodiment, but the upper case 146 in the second embodiment is provided with a displacement restriction rib 150 that is disposed opposite a positioning wall portion 156 (described later) provided on the lower case 148, with a heat-generating component (pre-charge resistor 22) sandwiched between them. Specifically, the displacement restriction rib 150 is provided to the right of the insertion holes 112 at the right end portion of the upper case 146, protruding downward from the upper bottom wall portion 102. In the second embodiment, the displacement restriction rib 150 has a substantially rectangular plate shape and is formed integrally with the upper case 146. The displacement restriction rib 150 has a predetermined length (front-rear dimension) inside the upper case 146 and protrudes to the vicinity of the lower opening of the upper case 146. In particular, in embodiment 2, reinforcing ribs 152 extending in a direction perpendicular to the longitudinal direction of the displacement control rib 150 (left-right direction) are integrally formed at both front-to-rear ends of the displacement control rib 150, thereby improving the deformation rigidity of the displacement control rib 150.

[0074] <Lower case 148> The lower case 148 of the second embodiment also has a shape similar to that of the lower case 100 of the first embodiment, and includes a bottom wall portion 114 through which the openings 28, 116 are formed in the thickness direction (up-down direction), as shown in Fig. 13. Furthermore, the openings 28 have insertion holes 30 formed at both front-rear end portions thereof so as to communicate with the openings 28. The holding portion 142 of the second embodiment is provided on the periphery of the openings 28.

[0075] <Retaining portion 142> As described above, the opening window 28 has a rectangular shape in a plan view, and the retaining portion 142 of the second embodiment includes a protruding wall portion 154 provided on each of a pair of opposing pieces (opposing pieces in the front-to-rear direction) of the opening window 28 and protruding inward (i.e., upward) of the case 144. The retaining portion 142 also includes a positioning wall portion 156 provided on one (the left in the second embodiment) of the other pair of opposing pieces (opposing pieces in the left-to-right direction) of the opening window 28 and protruding inward (i.e., upward) of the case 144. The positioning wall portion 156 has a generally rectangular plate shape and has a front-to-rear dimension generally equal to that of the opening window 28. Furthermore, the retaining portion 142 includes the aforementioned displacement restriction rib 150 provided on the upper case 146.

[0076] Specifically, the protruding wall portions 154 are provided on both front-rear sides of the opening window 28, i.e., to the left of each insertion hole 30. In particular, in the second embodiment, the protruding wall portions 154 are provided on both the left and right sides of the rear insertion hole 30, for a total of three protruding wall portions 154 in the lower case 148. Furthermore, as described above, the positioning wall portion 156 is provided on the left of the opening window 28, and the positioning wall portion 156 and each of the protruding wall portions 154 on both front-rear sides are connected by the bent portions 126, as in the first embodiment. Therefore, in the second embodiment, an insertion window portion 129 penetrating in the front-rear direction is formed between the opposing rear protruding wall portions 154. When the pre-charge resistor 22 is held by the holding portion 142, each held portion 94 of the pre-charge resistor 22 rests on the protruding end surface 158 of each protruding wall portion 154.

[0077] Also in the second embodiment, the upward protrusion dimension C (see FIG. 15 ) of each protruding wall portion 154 (the vertical dimension from the upper surface of the bottom wall portion 114 to the protruding end surface 158) is smaller than the upward protrusion dimension B of each fixed portion 42 provided on the housing 12. As a result, when the circuit unit 140 is fixed to the housing 12, each fixed portion 42 protrudes into the circuit unit 140 through each insertion hole 30 of the lower case 148, and each fixed portion 42 is positioned inside (above) the case 144, beyond the protruding end surface 158 of each protruding wall portion 154. In other words, when the circuit unit 140 is fixed to the housing 12, the upper surface of each fixed portion 42 is located above the protruding end surface 158 of each protruding wall portion 154.

[0078] <Displacement Restriction Piece 162> Furthermore, the holding portion 142 includes a displacement restriction piece 162 that extends from the protruding tip (upper end) of the positioning wall portion 156 toward the heat-generating component (pre-charge resistor 22), is positioned inward (above) of the case 144 relative to the protruding end faces 158 of each protruding wall portion 154, and faces the pre-charge resistor 22 across a gap 160 in the vertical direction. The displacement restriction piece 162 has a generally rectangular plate shape overall and has predetermined left-right and front-to-back dimensions. As a result, as shown in FIG. 11 , the upper surface 93 a of the pre-charge resistor 22 and the displacement restriction piece 162 overlap each other in vertical projection.

[0079] <Assembly of Circuit Unit 140> A specific example of a method for assembling the circuit unit 140 will be described below. Note that the method for assembling the circuit unit 140 is not limited to the aspect described below. Furthermore, in the method for assembling the circuit unit 140, descriptions of parts that have the same structure as in embodiment 1 will be omitted.

[0080] In the second embodiment, the pre-charge resistor 22 is brought into contact with the retaining portion 142 of the lower case 148, to which the relays 18a, 18b and the pre-charge relay 20 are fixed, from the right. The flange-shaped portions 90 of the metal case 82 are placed on the protruding end faces 158 of the protruding wall portions 154 that constitute the retaining portion 142, and the retained portions 94 at both left and right ends of each flange-shaped portion 90 are held by the retaining portion 142. This approach of the pre-charge resistor 22 to the retaining portion 142 from the right (leftward displacement) is restricted, for example, by the left wall of the metal case 82 abutting against the positioning wall portion 156. In particular, because the retaining portion 142 does not have a protruding wall portion 154 on the right side of the front insertion hole 30, the pre-charge resistor 22, from which the electric wires 72, 74 extend forward, can approach the positioning wall portion 156 from the right.

[0081] Then, with the precharge resistor 22 held on the holding portion 142, the upper case 146 is brought close from above as shown in Figure 14, and the upper case 146 and the lower case 148 are overlapped as shown in Figures 15 and 16. As a result, the concave and convex shapes on the outer peripheries of the upper case 146 and the lower case 148 fit together, completing the circuit unit 140 of the second embodiment.

[0082] That is, in the circuit unit 140 of the second embodiment, the peripheral wall 84 of the heat-generating component (precharge resistor 22) is positioned between the laterally opposed surfaces of the positioning wall 156 and the displacement-restricting rib 150 and between the longitudinally opposed surfaces of a pair of protruding wall portions 154 that face each other in the longitudinal direction. In this state, as described above, the displacement-restricting piece 162 is positioned above the precharge resistor 22 across the gap 160, preventing the precharge resistor 22 held by the holding portion 142 from being pulled out upward. Therefore, in the circuit unit 140, the precharge resistor 22 is surrounded by the displacement-restricting rib 150, the protruding wall portions 154, the positioning wall 156, and the displacement-restricting piece 162, allowing the precharge resistor 22 to move to some extent within these elements. As a result, the precharge resistor 22 is temporarily assembled within the circuit unit 140 during assembly of the circuit unit 140.

[0083] <Assembling the Circuit Unit 140 to the Heat Dissipation Target (Housing 12)> The method for assembling the circuit unit 140 to the housing 12 is not limited, but the same method as in the first embodiment can be employed. That is, the circuit unit 140 is placed on the upper surface 32 of the housing 12, and the fixed portions 42 protruding upward from the upper surface 32 are inserted into the circuit unit 140 through the insertion holes 30 provided in the lower case 148. As a result, the upper surfaces of the fixed portions 42 abut against the flange portions 90 of the metal cases 82 from below, and the flange portions 90 (particularly the held portions 94) are spaced upward from the protruding end surfaces 158 of the holding portions 142 (particularly the protruding wall portions 154). Then, screws 44 are inserted into the screw insertion grooves 92 through the insertion holes 112 in the upper case 146 and fastened to the screw fastening holes 46. This completes the assembly of the circuit unit 140 to the housing 12.

[0084] The circuit unit 140 of embodiment 2 having the above-described structure differs from the circuit unit 10 of embodiment 1 only in the insertion direction of the precharge resistor 22 relative to the holding portion 142, and therefore can achieve the same effects as embodiment 1.

[0085] <Modifications> Although the first and second embodiments have been described above as specific examples of the present disclosure, the present disclosure is not limited to these specific descriptions. Modifications, improvements, etc., within the scope of achieving the object of the present disclosure, are included in the present disclosure. For example, the following modifications of the embodiments are also included in the technical scope of the present disclosure.

[0086] (1) In the above embodiment, the heat dissipation target was the battery pack housing 12, but this is not limited to this. That is, the heat dissipation target may be any member that comes into thermal contact with a heat-generating component when the circuit unit according to the present disclosure is installed in a vehicle, and may be, for example, a metal member that constitutes the vehicle body. Note that the heat dissipation target does not need to be provided with a refrigerant flow path as described in the above embodiment.

[0087] (2) In the above embodiment, the heat-generating component is constituted by a precharge resistor 22, but this is not limited to this. The heat-generating component employed in the circuit unit according to the present disclosure may be any component that generates heat when current is applied, such as a relay, fuse, or precharge relay.

[0088] (3) In the above embodiment, the openings 28 and the insertion holes 30 were formed in communication with each other in the bottom wall portion 114 of the lower case 100, 148. However, the openings and the insertion holes may be formed separately. Furthermore, the shapes, sizes, numbers, etc. of the openings and the insertion holes are not limited, and the shapes, sizes, numbers, etc. of the openings can be appropriately set depending on the heat-generating component, and the shapes, sizes, numbers, etc. of the insertion holes can be appropriately set depending on the fixed portion provided on the heat dissipation target.

[0089] (4) In the above embodiments, the structure of the precharge resistor (metal clad resistor) constituting the heat-generating component is not limited as long as it has a metal case. In the above embodiments, the electric wires 72, 74 extending from the precharge resistor 22 extend from one end (front end) of the precharge resistor 22 in the longitudinal direction. However, in the case of the first embodiment, for example, two electric wires may extend from both ends of the precharge resistor in the longitudinal direction.

[0090] (5) In the above embodiment, the precharge circuit 68 is connected in parallel to the positive relay 18a. However, the precharge circuit may be connected in parallel to the negative relay.

[0091] REFERENCE SIGNS LIST 10 Circuit unit (first embodiment) 12 Housing (heat dissipation target) 14 Thermal contact portion 16 Fixing portion 18 Relay 18a Positive side relay 18b Negative side relay 20 Pre-charge relay 22 Pre-charge resistor (heat-generating component) 24 Case 26 Holding portion 28 Opening window 30 Insertion hole 32 Upper surface 34 Refrigerant flow path 36 Support portion 38 Bolt 40 Bolt fastening hole 42 Fixed portion 44 Screw 46 Screw fastening hole 48 Terminal portion 50 Current-carrying bus bar 50a to 50d First to fourth current-carrying bus bars 52 Bolt 54a to 54d Connection portion 56 Bolt 58 Main circuit 60a to 60d First to fourth heat dissipation bus bars 62 Heat dissipation portion 64 Insulating sheet 66 Elastic heat-conducting member 68 Precharge circuit 70, 72, 74 Electric wire 76 Terminal 78 Screw 80 Terminal portion 82 Metal case 84 Peripheral wall portion 86 Upper wall portion 88 Lower wall portion 90 Flange-shaped portion 92 Screw insertion groove 93a Upper surface 93b Lower surface 94 Held portion 96 Elastic heat conductive member 98 Upper case 100 Lower case 102 Upper bottom wall portion 104 Upper peripheral wall portion 106a to 106d Through window 108 Bolt insertion hole 110 Mounting portion 112 Insertion hole 114 Bottom wall portion 116 Opening window 118 Bolt insertion hole 120 Mounting portion 121 Lower surface 122 Frame portion 124 Side wall portion 126 Bent portion 128 Placement portion 129 Insertion window portion 130 Protruding end surface 132 Deflecting piece portion 134 Locking claw portion 136 Inclined surface 138 Gap 140 Circuit unit (Embodiment 2) 142 Holding portion 144 Case 146 Upper case 148 Lower case 150 Displacement restricting rib 152 Reinforcing rib 154 Protruding wall portion 156 Positioning wall portion 158 Protruding end surface 160 Gap 162 Displacement restricting piece

Claims

1. A circuit unit comprising: a heat generating component having a thermally contacting portion that thermally contacts a heat dissipation target and a fixing portion fixed to the heat dissipation target; a case that holds the heat generating component; a holding portion protruding inside the case to hold the heat generating component inside the case; an opening window penetrating the case to expose the thermally contacting portion of the heat generating component to the outside of the case; and an insertion hole penetrating the case into which a fixed portion provided on the heat dissipation target is inserted. By fixing the fixing portion of the heat generating component to the fixed portion inserted into the insertion hole, the heat generating component is separated from the holding portion, and the thermally contacting portion of the heat generating component is thermally contacted with the heat dissipation target.

2. The circuit unit according to claim 1, wherein in a state of being fixed to the heat dissipation target, the thermally contacting portion of the heat generating component is in contact with the heat dissipation target via an elastic heat conducting member.

3. The circuit unit according to claim 1 or 2, wherein the holding portion includes a frame portion surrounding the periphery of the opening window and protruding inward of the case, and a held portion protruding from the peripheral wall portion of the heat generating component is placed on the protruding end surface of the frame portion.

4. The holding portion protrudes more inward of the case than the frame portion and includes a deflectable piece portion that can be elastically deformed on the outer peripheral side of the opening window. The deflectable piece portion has a locking claw portion provided at the protruding tip and protruding to the inner peripheral side of the opening window. By the deflectable piece portion being elastically deformed to the outer peripheral side, assembly of the heat generating component to the frame portion is allowed. In a state where the held portion of the heat generating component is placed on the protruding end surface of the frame portion, the locking claw portion of the elastically restored deflectable piece portion overlaps the heat generating component with a gap in the protruding direction of the frame portion. The circuit unit according to claim 3.

5. The fixing portion of the heat generating component is provided at the same position as the held portion in the protruding direction of the frame portion. In a state of being fixed to the heat dissipation target, the fixed portion of the heat dissipation target is arranged inward of the case beyond the protruding end surface in the protruding direction of the frame portion. The circuit unit according to claim 3.

6. The case includes a lower case provided with the opening window and an upper case superposed on the lower case. The opening window has a rectangular shape. The holding portion includes protruding wall portions respectively provided on a pair of opposite sides of the opening window and protruding inward of the case, a positioning wall portion provided on one of the other pair of opposite sides of the opening window and protruding inward of the case, and a displacement restricting rib provided on the upper case and disposed opposite to the positioning wall portion with the heat generating component interposed therebetween. The heat generating component is disposed and positioned between the opposing surfaces of the positioning wall portion and the displacement restricting rib and between the opposing surfaces of the protruding wall portions. A held portion protruding from the peripheral wall portion of the heat generating component disposed between the protruding wall portions is placed on the protruding end surface of the protruding wall portion. The circuit unit according to claim 1 or claim 2.

7. The holding portion includes a displacement restricting piece that extends from the protruding tip of the positioning wall portion toward the heat generating component side, is disposed more inward of the case than the protruding end surface of the protruding wall portion, and is disposed opposite to the heat generating component with a gap therebetween. The circuit unit according to claim 6.

8. The fixing portion of the heat generating component is provided at the same position as the held portion in the protruding direction of the protruding wall portion. In a state of being fixed to the heat dissipation target, the fixed portion of the heat dissipation target is disposed more inward of the case beyond the protruding end surface in the protruding direction of the protruding wall portion. The circuit unit according to claim 6.

Images