Circuit unit

Abstract

Disclosed is a circuit unit in which an uneven compression state of an elastic heat conduction member interposed between a heat-generating component and a heat-dissipating object is suppressed to suppress deterioration of cooling performance due to an increase in partial thermal resistance of the elastic heat conduction member.　A circuit unit 10 includes a heat-generating component 22, a case 14, and a pressing component 16. The heat-generating component 22 has a thermal contact part 154 in thermal contact with a heat-dissipating object 12 via an elastic heat conduction member 68. The case 14 has an open window 44 exposing the thermal contact part 154 to the outside, and an insertion hole 46 into which a secured part 34 provided on the heat-dissipating object 12 is inserted. The pressing component 16 has a fixing part 108 that is fixed to the secured part 34 of the heat-dissipating object 12. In a state where the fixing part 108 is fixed to the secured part 34 inserted into the insertion hole 46, the pressing component 16 contacts the heat-generating component 22, and the pressing component 16, being fixed to the heat-dissipating object 12, presses the heat-generating component 22 against the elastic heat conduction member 68 without intervention of the case 14.

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, when the thermal contact portion of a heat-generating component fixed to a case is brought into contact with a heat dissipation target via an elastic heat-conducting sheet, as in the structure of Patent Document 1, the reaction force of the elastic heat-conducting sheet is not sufficient to compress the central portion of the heat-generating component, which is separated from the portion where the heat-generating component is fixed to the case. As a result, there is a risk that the thermal resistance in this portion will increase and cooling performance will deteriorate.

[0005] Therefore, we disclose a circuit unit that can prevent the compression state of the elastic heat conduction member interposed between the heat-generating component and the heat dissipation target from becoming uneven, thereby preventing deterioration of cooling performance due to an increase in the partial thermal resistance of the elastic heat conduction member.

[0006] The circuit unit of the present disclosure comprises a heat-generating component, a case that houses the heat-generating component, and a pressing component that presses the heat-generating component, wherein the heat-generating component has a thermal contact portion that is in thermal contact with a heat dissipation target via an elastic heat-conducting member, and an opposing surface that faces the thermal contact portion, the case has an opening that exposes the thermal contact portion of the heat-generating component to the outside, and an insertion hole into which a fixed portion provided on the heat dissipation target is inserted, the pressing component has a pressing surface that contacts the opposing surface of the heat-generating component, and a fixing portion that is fixed to the fixed portion of the heat dissipation target, and when the fixing portion is fixed to the fixed portion inserted in the insertion hole, the pressing surface of the pressing component contacts the opposing surface of the heat-generating component, and the pressing component fixed to the heat dissipation target presses the heat-generating component against the elastic heat-conducting member without going through the case.

[0007] According to the circuit unit of the present disclosure, it is possible to prevent the compression state of the elastic heat conduction member interposed between the heat-generating component and the heat dissipation target from becoming uneven, thereby preventing an increase in the partial thermal resistance of the elastic heat conduction member.

[0008] FIG. 1 is a perspective view showing a circuit unit according to the 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 that constitutes 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 that constitutes 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, corresponding to FIG. 5.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be described. A circuit unit of the present disclosure includes: (1) a heat-generating component, a case that houses the heat-generating component, and a pressing component that presses the heat-generating component, wherein the heat-generating component has a thermal contact portion that is in thermal contact with a heat dissipation target via an elastic heat conduction member and an opposing surface that faces the thermal contact portion, the case has an opening that exposes the thermal contact portion of the heat-generating component to the outside and an insertion hole into which a fixed portion provided on the heat dissipation target is inserted, the pressing component has a pressing surface that contacts the opposing surface of the heat-generating component and a fixing portion that is fixed to the fixed portion of the heat dissipation target, and when the fixing portion is fixed to the fixed portion inserted in the insertion hole, the pressing surface of the pressing component contacts the opposing surface of the heat-generating component, and the pressing component fixed to the heat dissipation target presses the heat-generating component against the elastic heat conduction member without using the case.

[0010] According to the circuit unit of this embodiment, the thermal contact portion of the heat-generating component housed in the case can be exposed through the case's opening and contacted with the heat dissipation target via the elastic heat conductive member. By employing a pressing component separate from the heat-generating component and the case, and by fastening the pressing component's fixing portion to the fixed portion of the heat dissipation target inserted into the case's insertion hole, the pressing surface of the pressing component can be brought into contact with the opposing surface of the heat-generating component, allowing the pressing surface of the pressing component fixed directly to the heat dissipation target to press the heat-generating component against the elastic heat conductive member without using the case. This prevents uneven compression of the elastic heat conductive member between the heat-generating component and the heat dissipation target, compared to conventional structures in which a heat-generating component fixed to a case is pressed against the heat dissipation target via the case. As a result, a circuit unit can be provided that prevents localized increases in thermal resistance of the elastic heat conductive member and the resulting deterioration of cooling performance.

[0011] The number of fixing portions of the pressing component and the number of fixed portions of the heat dissipation target can be set arbitrarily depending on the shape of the opposing surface of the heat-generating component. For example, if the opposing surface is annular, providing one fixing portion in the center of the pressing component and fixing it to one fixed portion located at the opposing location can also prevent the elastic heat conduction member from being compressed unevenly. Also, if the opposing surface of the heat-generating component is circular, elliptical, rectangular, or the like, providing multiple fixing portions located at multiple positions spaced apart from each other in the circumferential direction around the heat-generating component on the pressing component and fixing it to multiple fixed portions located at positions opposite the multiple fixing portions can advantageously prevent the elastic heat conduction member from being compressed unevenly.

[0012] (2) In the above (1), it is preferable that the pressing surface of the pressing part contacts the entire surface of the opposing surface of the heat-generating part. By pressing the pressing surface of the pressing part against the entire surface of the opposing surface of the heat-generating part, the elastic heat-conducting member can be compressed more evenly, and it is possible to more effectively prevent uneven compression and the resulting increase in partial thermal resistance and deterioration of cooling performance.

[0013] (3) In the above (1) or (2), it is preferable that the pressing surface of the pressing component has a rectangular shape, the pressing component has the fixing portions provided on both longitudinal ends of the pressing surface, and the pressing component has protruding ribs extending in the longitudinal direction. Since the fixing portions of the pressing component are provided on both longitudinal ends of the pressing surface, it is easy to apply the pressing force from the pressing surface evenly to the heat-generating component. Furthermore, since the pressing component has ribs extending in the longitudinal direction and extending between the fixing portions to which the fixing load on the heat dissipation target is applied, deformation of the pressing surface of the pressing component can be prevented, and the occurrence of uneven compression can be further effectively suppressed.

[0014] (4) In any one of (1) to (3) above, it is preferable that the case has a holding portion protruding from the interior of the case and engaging with the heat-generating component to hold the heat-generating component within the case, the heat-generating component has a mounting portion placed on the fixed portion and fixed to the fixed portion together with the fixing portion, and the heat-generating component is separated from the holding portion by fixing the mounting portion of the heat-generating component to the fixed portion. Because the case has a holding portion that engages with the heat-generating component to hold the heat-generating component within the case, before the circuit unit is fixed to the heat dissipation target, the engagement of the heat-generating component with the holding portion advantageously prevents the heat-generating component from escaping from the case to the outside through the opening. Furthermore, when the pressing component of the circuit unit is fixed to the fixed portion of the heat dissipation target, the mounting portion of the heat-generating component is fixed to the fixed portion together with the fixing portion, thereby separating the heat-generating component from the holding portion. This makes it possible to press the heat-generating component against the heat dissipation target by the pressing component without using the case, even when the case has a holding portion. As a result, it is possible to improve the workability of assembling the circuit unit and to achieve stable cooling performance at the same time.

[0015] (5) In the above (4), it is preferable that the retaining portion includes a frame portion surrounding 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 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 within the case, for example, during transportation of the circuit unit before being fixed to the fixed portion of the heat dissipation target.

[0016] (6) In the above (5), it is preferable that the holding portion includes a flexible piece 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 having a locking claw provided at a protruding tip and protruding toward the inner periphery of the opening window, the flexible piece being flexible and deformable toward the outer periphery to allow the assembly of the heat-generating component and the pressing component to the frame body portion, 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 of the flexible piece that has elastically returned to its original state overlaps the pressing component with a gap in between in the protruding direction of the frame body portion. This allows the heat-generating component and pressing component to not only be prevented from popping out of the opening window, but also from being displaced in the opposite direction by engagement with the locking claw portion, thereby making it possible to hold the heat-generating component and pressing component within the case more stably.

[0017] (7) In the above (5) or (6), it is preferable that, when fixed to the heat dissipation target, the fixed portion of the heat dissipation target is arranged to extend beyond the protruding end face of the frame body portion in the protruding direction of the frame body portion and be positioned inside the case. In this way, by fixing the mounting portion of the heat-generating component together with the fixing portion of the pressing component to the fixing portion, the heat-generating component can be separated from the holding portion (frame body portion), and the fixing portion of the heat-generating component can be directly fixed to the fixing portion of the heat dissipation target.

[0018] (8) In any one of (1) to (7) above, it is preferable that the case has positioning bosses arranged at multiple locations around the opening window and protruding beyond the fixing portion, and the pressing part has multiple positioning holes through which the positioning bosses are inserted, which are formed at positions corresponding to the positioning bosses. By inserting the positioning bosses into the positioning holes, the pressing part can be reliably guided to a predetermined assembly position. More preferably, when it is necessary to distinguish between the front and back of the pressing part, such as when the pressing part has ribs as in the above embodiment (3), the positions of the positioning bosses and the positioning holes can be asymmetrically positioned on the pressing part, thereby preventing incorrect assembly of the front and back of the pressing part. Furthermore, by making the shape of the pressing part, including not only the positioning bosses and the positioning holes but also the fixing portion, rotationally symmetric about the central axis, it is possible to more easily position the pressing part relative to the case, for example, without having to distinguish between the front and back and / or left and right directions of the pressing part.

[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 supply (e.g., a battery) (not shown) and a load (e.g., an inverter) (not shown). The circuit unit 10 includes a heat-generating component (in the first embodiment, a pre-charge resistor 22, described later). When power is applied to the heat-generating component, heat is dissipated through a heat dissipation target (a housing 12, described later) to which the circuit unit 10 is fixed. While the circuit unit 10 can be positioned in any orientation within a vehicle, 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 . In addition, when multiple identical components are illustrated, only some of the components may be designated by reference numerals, and the reference numerals may be omitted for the other components.

[0021] <Circuit unit 10> The circuit unit 10 includes a heat-generating component, a case 14 that houses the heat-generating component, and a pressing component 16 that presses the heat-generating component. Note that the circuit unit 10 of embodiment 1 includes a relay 18, a pre-charge relay 20, and a pre-charge resistor 22 as electrical components that generate heat when current is applied, but in embodiment 1, the structure of the present disclosure is applied to the pre-charge resistor 22 of the electrical components, and therefore the heat-generating component is constituted by the pre-charge resistor 22. In embodiment 1, not only the pre-charge resistor 22 but also the relay 18 and the pre-charge relay 20 are housed and held within the case 14.

[0022] <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. Housing the circuit unit 10 and the battery in this housing 12 constitutes a battery pack (not shown). That is, the circuit unit 10 is stacked and fixed on the top surface 24 of the housing 12, and heat generated by energizing electrical components provided in 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 in 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 26 may be formed within this metal plate. A known refrigerant may be used as the refrigerant flowing through the refrigerant flow path 26. The extension direction and length of the refrigerant flow path 26 shown in FIG. 1 are merely exemplary, and the extension direction and length of the refrigerant flow path are not limited.

[0023] 6, on the top surface 24 of the housing 12, support protrusions 28 that support the four corners of the circuit unit 10 are provided at four locations around the fixed position of the circuit unit 10 and protrude upward, and a bolt fastening hole 32 that opens upward is formed in the center of each support protrusion 28, into which a bolt 30 that fastens the circuit unit 10 is fastened. Furthermore, on the top surface 24 of the housing 12, at a predetermined location at the fixed position of the circuit unit 10, a fixed portion 34 to which a mounting portion 164 (described later) of the heat-generating component (pre-charge resistor 22) is fixed is provided so as to protrude upward.

[0024] In the first embodiment, a pair of fixed portions 34a, 34a face each other at a predetermined distance in the front-to-rear direction, and another pair of fixed portions 34b, 34b face each other at a predetermined distance in the left-to-right direction, for a total of four fixed portions 34a, 34b provided on the housing 12. In particular, in the first embodiment, each fixed portion 34b is provided at the center of each fixed portion 34a in the front-to-rear direction, and each fixed portion 34a is provided at the center of each fixed portion 34b in the left-to-right direction. That is, each fixed portion 34a, 34b is disposed in a position that is rotationally symmetrical about a central axis extending in the up-down direction through the center of each fixed portion 34a, 34b. Each of these fixed portions 34a, 34b has a generally rectangular columnar shape. As shown in FIG. 5 , each fixed portion 34a has a protrusion dimension B from the top surface 24 of the housing 12, and each fixed portion 34b has a protrusion dimension B' that is slightly larger than the protrusion dimension B. At the upper end of each of the fixed portions 34a, 34b, a screw fastening hole 38 is formed into which a screw 36 is fastened to fasten each of the mounting portions 164 and each of the fixed portions 34a, 34b.

[0025] <Case 14> As described above, the circuit unit 10 includes a case 14 that holds the relays 18 (positive and negative relays 18a, 18b, described below), the precharge relay 20, and the precharge resistor 22. In the first embodiment, the case 14 has a hollow rectangular parallelepiped shape, with the left-right dimension being larger than the front-rear dimension. In particular, in the first embodiment, the case 14 includes an upper case 40 and a lower case 42 that can be assembled and disassembled relative to each other in the vertical direction. The upper case 40 and the lower case 42 are formed, for example, from a synthetic resin. While the method for fastening the upper case 40 and the lower case 42 is not limited, in the first embodiment, the upper case 40 and the lower case 42 are fastened to each other by inserting the bolts 30 described above into the four corners of the circuit unit 10 and fastening them into the bolt fastening holes 32 provided in each support protrusion 28 of the housing 12 with the upper case 40 and the lower case 42 overlapping each other.

[0026] The case 14 also has an opening 44 that exposes a thermal contact portion 154 (described later) of the heat-generating component (pre-charge resistor 22) to the outside, and insertion holes 46 into which the fixed portions 34a, 34b provided on the heat dissipation target (housing 12) are inserted. Both the opening 44 and the insertion holes 46 are provided in the lower case 42. In the first embodiment, four fixed portions 34a, 34b are provided, and therefore four insertion holes 46a, 46b corresponding to the fixed portions 34a, 34b are formed in the lower case 42. That is, a pair of insertion holes 46a, 46a corresponding to each fixed portion 34a is provided at a predetermined distance in the front-rear direction, and another pair of insertion holes 46b, 46b corresponding to each fixed portion 34b is provided at a predetermined distance in the left-right direction. In other words, the insertion holes 46a, 46b are also arranged at positions that are rotationally symmetrical about the central axis that extends in the up-down direction through the center of each insertion hole 46a, 46b.

[0027] <Upper Case 40> The upper case 40 is generally box-shaped and opens downward, and includes an upper bottom wall 48 and an upper peripheral wall 50 that protrudes downward from the outer periphery of the upper bottom wall 48. Rectangular through-windows 52a to 52d that penetrate the upper bottom wall 48 in the thickness direction (vertical direction) are provided at positions corresponding to connection portions 122a to 122d of first to fourth current-carrying bus bars 118a to 118d (described later) when the circuit unit 10 is assembled. Mounting portions 56 with bolt insertion holes 54 are provided at the four corners of the periphery of the upper case 40, and each mounting portion 56 is located somewhat above the lower end of the upper peripheral wall 50. In addition, in the upper bottom wall portion 48, circular insertion holes 58 that penetrate in the thickness direction are provided at positions corresponding to each insertion hole 46a, 46b of the lower case 42 when the circuit unit 10 is assembled, and each screw 36 is fastened from above through each insertion hole 58 into the bolt fastening holes 32 in each fixed portion 34a, 34b.

[0028] 7 and other figures, the lower case 42 has a bottom wall 60 that is generally flat, and the bottom wall 60 has substantially the same rectangular shape in plan view as the upper case 40. As a result, when the upper case 40 and the lower case 42 are overlapped and fixed together, the bottom wall 60 of the lower case 42 covers the lower opening of the upper case 40.

[0029] The bottom wall 60 has rectangular opening windows 62 penetrating in the thickness direction (vertical direction) at positions corresponding to the heat dissipation portions 130 of the first to fourth heat dissipation bus bars 128a to 128d (described later) when the circuit unit 10 is assembled. The bottom wall 60 also has the aforementioned opening windows 44 penetrating in the thickness direction (vertical direction) at positions corresponding to the thermal contact portions 154 (bottom wall portions 152 of the metal case 146) (described later) of the pre-charge resistors 22 (metal-clad resistors) (described later). In the first embodiment, the opening windows 44 are rectangular and have a larger area in plan view than the bottom surface 156 (described later) of the pre-charge resistors 22. This allows the opening windows 44 to expose the thermal contact portions 154 (bottom wall portions 152) of the metal case 146 so that they can be in thermal contact with the housing 12 when the circuit unit 10 is assembled.

[0030] Furthermore, the aforementioned insertion holes 46a, 46b, into which the fixed portions 34a, 34b of the housing 12 are inserted, are formed on both front-rear and left-right sides of the opening window 44. These insertion holes 46a, 46b have a generally rectangular shape. In the first embodiment, the opening window 44 and the insertion holes 46a on both front-rear sides are in communication with each other, and the insertion holes 46a are connected to each other on both front-rear sides of the inner peripheral surface of the opening window 44. Furthermore, the opening window 44 and the insertion holes 46b on both left-right sides are formed independently of each other, and the insertion holes 46b are formed at a predetermined distance from the opening window 44 in the left-right direction.

[0031] In the first embodiment, when the circuit unit 10 is fixed to the housing 12, an insulating sheet 64 and an elastic heat-conducting member 66 are stacked and housed in each opening window 62 provided below each heat dissipation section 130. This allows each heat dissipation section 130 of the first to fourth heat dissipation bus bars 128a to 128d to be in electrically insulated and thermally conductive contact with the housing 12, which is overlaid on the bottom wall 60. 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 underside of each heat dissipation section 130 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, the insulating sheet 64 and the elastic heat-conducting member 66 are housed within each opening window 62. Known materials may be used for the insulating sheet 64 and the elastic heat conducting member 66, and in particular, the elastic heat conducting member 66 may be, for example, a heat conducting sheet or gap filler having good thermal conductivity.

[0032] Furthermore, when the circuit unit 10 is fixed to the housing 12, an elastic heat conductive member 68 is housed in the opening 44 provided below the thermal contact portion 154 of the pre-charge resistor 22. This allows the thermal contact portion 154 to be in thermally conductive contact with the housing 12. The wire-wound resistor constituting the pre-charge resistor 22 is housed in an insulated state in a metal case 146 (described later). Therefore, even when the circuit unit 10 is energized, the metal case 146 remains electrically insulated, and the insulating sheet 64 does not need to be disposed within the opening 44. The elastic heat conductive member 68 is fixed (e.g., glued) to the lower surface 156 of the thermal contact portion 154 (the lower wall portion 152 of the metal case 146), for example, when the circuit unit 10 is fixed to the housing 12. Therefore, when the circuit unit 10 is fixed to the housing 12, the elastic heat conductive member 68 is housed and disposed within the opening 44. The elastic heat conducting member 68 may be made of the same material as the elastic heat conducting member 66 provided below the relays 18 (positive and negative side relays 18a, 18b, described below). Each of these elastic heat conducting members 66, 68 may be initially in the form of a rectangular sheet, or may be initially in the form of a gel or grease that hardens into a sheet upon exposure to heat or light.

[0033] Furthermore, mounting portions 72 having bolt insertion holes 70 are provided at the four corners of the periphery of the lower case 42 (bottom wall portion 60), and each mounting portion 72 is located somewhat higher than the remaining portions of the bottom wall portion 60. 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 74 of the lower case 42. In this manner, the mounting portions 56, 72 are formed at the four corners of the periphery of the outer periphery of the upper case 40 and the outer periphery of the lower case 42, thereby providing corresponding concave and convex shapes. As a result, when the upper case 40 and the lower case 42 are stacked vertically, these concave and convex shapes fit together, allowing the upper case 40 and the lower case 42 to be positioned relative to each other in the horizontal direction.

[0034] <Retention Portion 76> The case 14 has a retention portion 76 that protrudes into the case 14 and engages with the heat-generating component (pre-charge resistor 22) to retain the pre-charge resistor 22 within the case 14. In the first embodiment, the lower case 42 has the retention portion 76, which protrudes upward into the case 14. The retention portion 76 also includes a frame portion 78 that surrounds the window 44 and protrudes upward into the case 14. That is, the frame portion 78 protrudes in the vertical direction (particularly, from bottom to top). Specifically, the frame portion 78 has a pair of side walls 80, 80 that extend in the front-to-rear direction at both left and right edges of the window 44, and each of these side walls 80 has a larger front-to-rear dimension than the window 44. Both front-rear end portions of each side wall portion 80 are bent in a crank shape, and are positioned laterally inward of the intermediate front-rear end portion via bent portions 82. These front-rear end portions of each side wall portion 80 are support portions 84 on which flange-like portions 158 of a metal case 146 (described later) of the precharge resistor 22 are placed and supported.

[0035] Each support portion 84 is located outward in the front-rear direction from the window opening 44, and in the first embodiment, the insertion holes 46a are formed to be connected to both front-rear end portions of the window opening 44, and therefore each support portion 84 is provided on both left and right sides of each insertion hole 46a. In other words, at both front-rear end portions of the frame body portion 78, insertion windows 86 that penetrate in the front-rear direction are provided between opposing support portions 84, and each insertion window 86 connects the inside and outside of the frame body portion 78 to each other. In the first embodiment, two electric wires 136, 138, which will be described later, extend from the front end of the precharge resistor 22, and when the precharge resistor 22 is held by the frame body portion 78 (holding portion 76), each of the electric wires 136, 138 extends to the outside through the front insertion window portion 86. However, depending on the wiring configuration of the precharge circuit 132, which will be described later, each of the electric wires 136, 138 may also extend to the outside through the rear insertion window portion 86.

[0036] More specifically, flange-shaped portions 158 (particularly held portions 166, which are both left-right end portions) of a metal case 146 (described later) are placed on both front-rear end portions of the protruding end surface (upper end surface) 88 of the frame portion 78, i.e., on the protruding end surfaces 88 of the support portions 84. That is, the flange-shaped portions 158 of the metal case 146 of the precharge resistor 22 are placed in a manner of engagement with the support portions 84 of the holder 76, thereby holding the precharge resistor 22 in the holder 76. In this state, a peripheral wall portion 148 of the metal case 146 (described later) is housed between the side wall portions 80 of the frame portion 78.

[0037] Here, the upward protrusion dimension A (the vertical dimension from the upper surface of the bottom wall 60 to the protruding end face 88) of the frame body portion 78 (see FIGS. 5 and 9 ) is smaller than the upward protrusion dimension B (the vertical dimension from the upper surface 24 of the housing 12 to the upper surface of each of the fixed portions 34a, 34b) (see FIG. 5 ) of each of the fixed portions 34a, 34b provided on the housing 12. In particular, as will be described later, when the circuit unit 10 is fixed to the housing 12, the fixed portions 34a, 34b protrude into the circuit unit 10 through the insertion holes 46a, 46b of the lower case 42, and are positioned inside (above) the case 14 beyond the protruding end face 88 in the protruding direction (vertical direction) of the frame body portion 78. In other words, when the circuit unit 10 is fixed to the housing 12 , the upper surfaces of the fixed portions 34 a and 34 b are positioned above the protruding end surface 88 of the frame portion 78 .

[0038] <Flexible Pieces 90> The retaining portion 76 also includes flexible pieces 90 that protrude upward, more inward of the case 14 than the frame portion 78, and are capable of flexible deformation (elastic deformation in the first embodiment) toward the outer periphery of the opening window 44. In the first embodiment, the flexible pieces 90 are provided in the middle portion of each side wall portion 80 in the front-to-rear direction, and in particular in the first embodiment, a pair of flexible pieces 90, 90 are provided spaced apart from each other in the front-to-rear direction in the middle portion of each side wall portion 80 in the front-to-rear direction. Therefore, in the first embodiment, a total of four flexible pieces 90 are provided in the retaining portion 76.

[0039] Each flexible piece 90 has a locking claw 92 at its protruding tip (upper end) that protrudes toward the inner periphery (inward in the left-right direction) of the opening window 44. When the pre-charge resistor 22 and the pressing component 16 are assembled to the lower case 42, each locking claw 92 protrudes inward in the left-right direction to a position where it vertically overlaps a base plate 104 (described later) of the pressing component 16. In other words, when the pre-charge resistor 22 and the pressing component 16 are assembled to the lower case 42, the protruding tip (inner end in the left-right direction) of each locking claw 92 overlaps both left-right edge portions of the base plate 104 in a plan view. Note that in the first embodiment, the pressing component 16 and the pre-charge resistor 22 have substantially the same planar shape, and the protruding tip of each locking claw 92 also overlaps the pre-charge resistor 22 (an upper wall 150 of a metal case 146 (described later)) in a plan view, but this is not limited to this. That is, the locking claws 92 and the precharge resistor 22 (upper wall portion 150) do not need to overlap each other in a planar projection.

[0040] The upper surface of each locking claw 92 is provided with an inclined surface 94 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 76, the pre-charge resistor 22 is brought close to the holding portion 76 from above, causing both left-right edge portions of the lower surface 156 of the metal case 146 (described later) to abut against the inclined surface 94 of each locking claw 92, elastically deforming each flexible piece 90 outward in the left-right direction. This allows the pre-charge resistor 22 to be assembled to the frame portion 78. Furthermore, a pressing part 16 is assembled to the holding portion 76 (frame portion 78) from above the pre-charge resistor 22, similar to the pre-charge resistor 22. When each flange-like portion 158 of the metal case 146 is placed on the protruding end surface 88 of each support portion 84 and the pressing part 16 is placed on top of the precharge resistor 22, each flexible piece 90 elastically restores its original shape (elastic recovery), so that the locking claw portion 92 of each flexible piece 90 overlaps the pressing part 16 with a gap 96 in the protruding direction (vertical direction) of the frame body portion 78, as shown in FIG. 9 and other figures.

[0041] <Positioning Bosses 98> The case 14 has positioning bosses 98 that are arranged at multiple locations around the opening window 44 opposite the pre-charge resistor 22 and that protrude beyond fixing portions 108 (described later) of the pressing component 16. In the first embodiment, the positioning bosses 98 are provided on the lower case 42, and as shown in FIG. 7 and other figures, are provided adjacent to and laterally outward from a pair of side wall portions 80 that face each other in the left-right direction. That is, in the first embodiment, a pair of positioning bosses 98 are provided on the lower case 42, and one (right) positioning boss 98 is provided rearward of the right insertion hole 46 b, and the other (left) positioning boss 98 is provided in front of the left insertion hole 46 b. In particular, in embodiment 1, since each insertion hole 46a, 46b is provided on both the front-to-back and left-to-right sides of the opening window 44, each insertion hole 46a, 46b and each positioning boss 98 is formed in a rotationally symmetrical position around a central axis extending in the up-down direction through the center of the opening window 44 (the intersection of each diagonal line in the rectangular opening window 44) when viewed in a plane.

[0042] More specifically, each positioning boss 98 includes a base 100 having a substantially rectangular parallelepiped outer shape, and a pin-shaped portion 102 that protrudes upward from the center of the upper end surface of the base 100. Each of the bases 100 and each of the pin-shaped portions 102 has a predetermined vertical dimension, and when the pressing part 16 is assembled to the case 14 (lower case 42), the protruding tip (upper end) of each pin-shaped portion 102 is located above a fixing portion 108 of the pressing part 16, which will be described later.

[0043] <Pressing Component 16> As shown in Figures 5 and 6, the pressing component 16 has an overall rectangular plate shape and is formed from a metal with relatively high deformation rigidity in the first embodiment. Specifically, the pressing component 16 includes a base plate portion 104 that is generally rectangular in plan view. When the pressing component 16 is attached to the lower case 42, the pressing component 16 (base plate portion 104) extends in the front-to-rear direction. The pressing component 16 is placed over the heat-generating component (pre-charge resistor 22) from above to press the pre-charge resistor 22. The lower surface of the pressing component 16 (base plate portion 104) forms a pressing surface 106 that contacts the upper surface (opposing surface 157, described later) of the pre-charge resistor 22. In other words, the pressing surface 106 extends in a generally rectangular shape in plan view.

[0044] The base plate portion 104 has predetermined front-rear and left-right dimensions, with the longitudinal direction being the front-rear direction. Specifically, the base plate portion 104 has approximately the same front-rear and left-right dimensions as an upper wall portion 150 (described later) of the pre-charge resistor 22. That is, in the first embodiment, the entire lower surface of the base plate portion 104 serves as a pressing surface 106 that contacts an opposing surface 157 of the pre-charge resistor 22, and the pressing surface 106 contacts the entire opposing surface 157.

[0045] When the pressing part 16 is assembled to the lower case 42, both front-rear direction end portions of the base plate 104 are superimposed from above on the support portions 84 at both front-rear direction end portions of each side wall portion 80 and on the insertion holes 46a on both sides in the front-rear direction. Screw insertion holes 107 penetrating in the plate thickness direction (front-rear direction) are formed at both front-rear direction end portions of the base plate 104, and the both front-rear direction end portions of the base plate 104 are fixed to the fixed portions 34a on both front-rear direction end portions of the housing 12 by screws 36 inserted into the screw insertion holes 107. Therefore, both front-rear direction end portions of the base plate 104 (pressing surface 106) (particularly the areas around the screw insertion holes 107) are fixing portions 108 fixed to the fixed portions 34a.

[0046] A pair of outward protrusions 110, 110 protruding outward in the left-right direction are provided in the center of the base plate portion 104 in the front-rear direction. These outward protrusions 110 are identical in shape and have predetermined front-rear and left-right dimensions. Specifically, in a plan view of the pressing part 16 assembled to the lower case 42, each outward protrusion 110 overlaps with the insertion holes 46b and positioning bosses 98 on both the left and right sides of the lower case 42. Each outward protrusion 110 has a screw insertion hole 107 formed in the center of the front-rear direction at a position corresponding to the screw fastening hole 38 in each fixed portion 34b. Furthermore, a positioning hole 112, through which the pin-shaped portion 102 is inserted, is formed at the front-rear end of each outward protrusion 110 at a position corresponding to the pin-shaped portion 102 in each positioning boss 98.

[0047] As will be described later, when the circuit unit 10 is fixed to the housing 12, both left and right end portions (outer protrusions 110) of the base plate portion 104 are fixed to the fixed portions 34b on both left and right sides of the housing 12 by screws 36 inserted into the screw insertion holes 107 in each outer protrusion 110. Therefore, fixing portions 108 that are fixed to the fixed portions 34b are also formed by the outer protrusions 110 (particularly the portions around the screw insertion holes 107).

[0048] Each of these outward protrusions 110 is formed so as to be positioned between the respective flexible piece portions 90 in the holding portion 76 in the front-to-rear direction when the pressing part 16 is assembled to the lower case 42, so that the respective outward protrusions 110 and the respective flexible piece portions 90 do not interfere with each other when the pressing part 16 is assembled to the lower case 42.

[0049] Furthermore, in the first embodiment, a rib 114 extending in the longitudinal direction (front-rear direction) of the pressing part 16 is provided to protrude upward on the surface (top surface) of the base plate part 104 opposite the pressing surface 106. This rib 114 extends with a predetermined front-rear dimension at the center of the pressing part 16 in the left-right direction, between the fixing parts 108, 108 in the front-rear direction. By providing such a rib 114, deformation of the pressing part 16 can be suppressed even when the pressing part 16 is fixed to the fixing parts 34a, 34b of the housing 12 with the screws 36, as described below.

[0050] The pressing part 16 has a rotationally symmetric shape about a central axis extending in the up-down direction through the center of the base plate 104 (the intersection of the diagonals of the rectangular base plate 104). For example, the pressing part 16 shown in FIG. 3 can be assembled to the lower case 42 even when rotated 180 degrees about the central axis. On the other hand, the pressing part 16 is not symmetrical with respect to a line L1 extending in the front-rear direction through the center in the left-right direction or a line L2 extending in the left-rear direction through the center in the front-rear direction. This prevents the pressing part 16 shown in FIG. 3 from being assembled to the lower case 42 upside down (upside down). Therefore, by shaping the pressing part 16 as described above, incorrect assembly in an upside-down state is reliably prevented, and identification of the front-rear or left-right direction is unnecessary, making it easier to assemble the pressing part 16 to the lower case 42.

[0051] <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 116, 116 (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 116 is exposed on the surface of each relay 18a, 18b.

[0052] The terminals 116 are input and output terminals for the relays 18a and 18b, and for example, in the positive relay 18a, the left terminal 116 is an input terminal on the positive side, and the right terminal 116 is an output terminal on the positive side. In addition, in the negative relay 18b, the left terminal 116 is an output terminal on the negative side, and the right terminal 116 is an input terminal on the negative side.

[0053] An energizing bus bar 118 is placed over each terminal 116 of each of the relays 18a, 18b and fixed with a bolt 120. That is, the circuit unit 10 includes first and second energizing bus bars 118a, 118b connected to the input and output terminals 116, 116 of the positive relay 18a, and third and fourth energizing bus bars 118c, 118d connected to the input and output terminals 116, 116 of the negative relay 18b. When the circuit unit 10 is assembled, the ends of the first to fourth current-carrying bus bars 118a to 118d are exposed to the outside through through windows 52a to 52d provided in the upper case 40 of the case 14, and each of them forms input and output connection parts 122a, 122b on the positive side and input and output connection parts 122c, 122d on the negative side.

[0054] The input connection portion 122a on the positive side and the input connection portion 122c 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 122b on the positive side and the output connection portion 122d 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 122a to 122d and the conductive members can be fixed with a bolt 124.

[0055] Thus, the relays 18a, 18b, the first to fourth current-carrying bus bars 118a to 118d, and the above-mentioned conductive members form a main circuit 126 between the battery and the inverter. By switching the relays 18a, 18b between ON and OFF in the main circuit 126, the main circuit 126 between the battery and the inverter can be switched between a conducting state and a non-conducting state.

[0056] In addition to the first to fourth current-carrying bus bars 118a to 118d, first to fourth heat-dissipating bus bars 128a to 128d are fastened to the terminals 116 of the positive and negative relays 18a, 18b by bolts 120. Each of the first to fourth heat-dissipating bus bars 128a to 128d 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 extends in the horizontal direction (a direction perpendicular to the vertical direction). The upper ends of the heat-dissipating bus bars 128a to 128d are fixed to the terminals 116 of the relays 18a, 18b by bolts 120, and their lower ends extend in the front-to-rear direction and are located below the relays 18a, 18b.

[0057] A heat dissipation section 130 is formed by a portion extending in the front-rear direction at the lower end of each of these heat dissipation bus bars 128a to 128d, and each heat dissipation section 130 is in thermal contact with the housing 12, which is the heat dissipation target, via the insulating sheet 64 and the elastic heat conductive member 66. With this structure, each terminal section 116 of each relay 18a, 18b is in thermal contact with the housing 12 via each of the heat dissipation bus bars 128a to 128d, the insulating sheet 64, and the elastic heat conductive member 66, and heat generated when current is applied to each relay 18a, 18b can be dissipated from the housing 12.

[0058] <Precharge Circuit 132> A precharge circuit 132 is connected in parallel to the positive relay 18a in the main circuit 126. Specifically, in the precharge circuit 132, a precharge relay 20 and a precharge resistor 22 are connected in series. The precharge relay 20 and the input terminal 116 of the positive relay 18a are electrically connected by an electric wire 134, and the precharge resistor 22 and the output terminal 116 of the positive relay 18a are electrically connected by an electric wire 136. The precharge relay 20 and the precharge resistor 22 are also electrically connected by an electric wire 138.

[0059] A terminal 140 is provided on at least one end of each of the electric wires 134, 136, 138, and each terminal 140 is overlapped with each terminal portion 116 of the positive side relay 18a or each terminal portion 144 (described later) of the precharge relay 20, and is fixed by a bolt 120 or a screw 142.

[0060] <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 144, 144 (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 144 is exposed on the top surface of the pre-charge relay 20. A terminal 140 provided at the end of the electric wire 134 connecting the positive relay 18a and the pre-charge relay 20 is overlapped with the input terminal 144 (left terminal 144) of the pre-charge relay 20 and fixed with a screw 142. Furthermore, a terminal 140 provided at the end of the electric wire 138 connecting the pre-charge relay 20 and the pre-charge resistor 22 is overlapped with the output terminal 144 (right terminal 144) of the pre-charge relay 20 and fixed with a screw 142.

[0061] <Pre-charge Resistor 22> The pre-charge resistor 22 is configured using a metal-clad resistor. Because a known type can be used as the pre-charge resistor 22 (metal-clad resistor), detailed description will be omitted. However, the pre-charge resistor 22 is configured by sealing a wire-wound resistor (not shown) in an insulated state in a metal case 146. Note that in cross-sectional views such as FIG. 5, the internal structure of the pre-charge resistor 22 is not shown, and only the metal case 146 is shown. In other words, the metal case 146 of the pre-charge resistor 22 is hollow, and a wire-wound resistor (not shown) is housed in an insulated state inside the metal case 146. In embodiment 1, the metal case 146 of the pre-charge resistor 22 is hollow and approximately rectangular, and is disposed so as to extend in the front-to-rear direction. That is, the metal case 146 is configured to include a substantially cylindrical peripheral wall portion 148 including wall portions on both the front-to-rear and left-to-right sides, an upper wall portion 150 covering the upper opening of the peripheral wall portion 148, and a lower wall portion 152 covering the lower opening of the peripheral wall portion 148.

[0062] The metal case 146 of this precharge resistor 22 (metal clad resistor) has a thermal contact portion 154 that is in thermal contact with the housing 12, which is the heat dissipation target. In the first embodiment, when the circuit unit 10, which will be described later, is fixed to the housing 12, the metal case 146 is placed on the housing 12 via an elastic heat conductive member 68 that is placed on a lower surface 156 of the precharge resistor 22 (the lower surface of the lower wall portion 152), and the thermal contact portion 154 is formed by the lower wall portion 152 that constitutes the hollow metal case 146. Since the thermal contact portion 154 is formed by the lower wall portion 152 of the metal case 146, an opposing surface 157 of the metal case 146 that faces the thermal contact portion 154 is formed by the upper surface of the precharge resistor 22 (the upper surface of the upper wall portion 150).

[0063] In particular, in the first embodiment, flange-like portions 158 are provided on both front-rear direction sides of the upper end portion (or upper wall portion 150) of the peripheral wall portion 148 of the metal case 146. Each of these flange-like portions 158 has a widthwise (left-right) dimension that is approximately equal to that of the upper wall portion 150 (or peripheral wall portion 148) and a predetermined protruding dimension (front-rear dimension), and a screw insertion groove 160 is provided in the left-right central portion of each flange-like portion 158, through which the above-mentioned screw 36 that secures the pre-charge resistor 22 is inserted. Due to the provision of each flange-like portion 158, the upper surface (opposing surface) 157 of the pre-charge resistor 22 has a larger area than the lower surface 156 of the pre-charge resistor 22 when projected in the vertical direction.

[0064] As will be described later, the flange-shaped portions 158 are placed on the respective fixed portions 34a of the housing 12, and the screws 36 are inserted into the screw insertion grooves 160 and fastened to the screw fastening holes 38, thereby fixing the mounting portions 164 of the heat-generating component (pre-charge resistor 22) to the fixed portions 34a. Therefore, the mounting portions 164 are formed by the portions of the flange-shaped portions 158 surrounding the screw insertion grooves 160 (the central portions of the flange-shaped portions 158 in the left-right direction). When the circuit unit 10 is fixed to the housing 12 as described above, the screws 36 are inserted into the respective screw insertion holes 107 of the pressing component 16 and fastened to the respective screw fastening holes 38. In other words, the pressing component 16 and the pre-charge resistor 22 (metal case 146) are placed on top of each other, so that the screw insertion holes 107 and the screw insertion grooves 160 communicate with each other in the vertical direction. Then, the fixing portions 108 are fixed to the fixed portions 34a with the flange-shaped portions 158 (the mounting portions 164) sandwiched therebetween by the screws 36 inserted into the screw insertion holes 107 and the screw insertion grooves 160. Therefore, the mounting portions 164 of the precharge resistor 22 (metal case 146) are fixed to the fixed portions 34a together with the fixing portions 108 of the pressing part 16.

[0065] Furthermore, both left and right end portions of each flange-shaped portion 158 are placed on holding portions 76 that protrude into the interior of the case 14 (lower case 42), thereby holding the heat-generating component (pre-charge resistor 22) within the case 14. Therefore, both left and right end portions of each flange-shaped portion 158 form held portions 166. As a result, in the first embodiment, each placing portion 164 and each held portion 166 are both provided on each flange-shaped portion 158, and are therefore provided at the same position in the up-down direction.

[0066] As described above, the pre-charge resistor 22 is connected to the electric wire 136 connected to the positive relay 18a and the electric wire 138 connected to the pre-charge relay 20. Specifically, the electric wire 136 is connected to one end of a winding provided inside the pre-charge resistor 22, and the electric wire 138 is connected to the other end. The electric wires 136, 138 connected to both ends of the winding extend from the inside to the outside of the metal case 146. In the first embodiment, the electric wires 136, 138 extend from one end of the metal case 146 in the longitudinal direction (the front end in the first embodiment). The terminals 140 provided at the ends of the electric wires 136, 138 are overlapped with the output terminal 116 of the positive relay 18a and the output terminal 144 of the pre-charge relay 20, respectively, and are fixed by the bolts 120 and the screws 142, respectively.

[0067] <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.

[0068] First, the first to fourth current-carrying bus bars 118a to 118d and the first to fourth heat-dissipating bus bars 128a to 128d are placed on the terminal portions 116 of the relays 18a, 18b, respectively, and then secured with the bolts 120. At this time, the terminals 140 provided at the ends of the electric wires 134, 136 are also placed on the terminal portions 116 of the positive relay 18a, and then secured together with the bolts 120. Then, the relays 18a, 18b and the pre-charge relay 20 are placed on the lower case 42 and secured with bolts or screws.

[0069] The precharge resistor 22 is then brought close to the retaining portion 76 of the lower case 42 from above, and assembled while elastically deforming each flexible piece 90 outward in the left-right direction. The locking claws 92 of each flexible piece 90 climb over the upper wall portion 150 of the metal case 146, causing each flexible piece 90 to elastically restore its original shape. As a result, the flange-like portions 158 of the metal case 146 are placed on the protruding end faces 88 of the support portions 84 of the retaining portion 76, and the retained portions 166 at both left-right ends of each flange-like portion 158 are held by the retaining portion 76.

[0070] Next, similar to the precharge resistor 22, the pressing part 16 is brought close to the holding part 76 from above, and the flexible pieces 90 are elastically deformed outward in the left-right direction while being assembled. At this time, the pin-shaped portions 102 of the positioning bosses 98 on the lower case 42 are inserted into the positioning holes 112 on the pressing part 16, so that the pressing part 16 is positioned relative to the lower case 42 and assembled. The locking claws 92 on the flexible pieces 90 overcome the base plate portions 104 on the pressing part 16, causing the flexible pieces 90 to elastically restore their original shape. This causes the pressing surface 106, which is the lower surface of the pressing part 16, to overlap the upper surface (opposing surface 157) of the metal case 146. In particular, the insertion of the pin-shaped portions 102 into the positioning holes 112 prevents the pressing part 16 from tilting relative to the metal case 146, and the pressing surface 106 and the opposing surface 157 are overlapped with almost no gap between them. As a result, the metal case 146 is placed on the holding portion 76 , and the pressing part 16 is placed on the metal case 146 .

[0071] In this state, the inner left-right ends of each locking claw 92 overlap in the up-down direction with both left-right side edges of the base plate 104, and even when the pre-charge resistor 22 and the pressing part 16 are displaced upward, for example, the locking claws 92 engage with the base plate 104, preventing the pre-charge resistor 22 and the pressing part 16 from slipping out upward from the holding part 76. In other words, in this state, the pre-charge resistor 22 and the pressing part 16 can be displaced in the up-down direction within the gaps 96 between the locking claws 92 and the base plate 104, and are temporarily assembled to the lower case 42.

[0072] Next, as shown in FIG. 8 , the upper case 40 is brought close from above to the lower case 42, in which the relays 18 a, 18 b, the pre-charge relay 20, the pre-charge resistor 22, and the pressing element 16 have been assembled, and the upper case 40 and the lower case 42 are overlapped as shown in FIG. 9 . This causes the mounting portions 56 of the upper case 40 to overlap the mounting portions 72 of the lower case 42, and the concave and convex shapes on the outer peripheries of the upper case 40 and the lower case 42 to fit together as described above. As a result, horizontal misalignment of the upper case 40 and the lower case 42 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 40 and the lower case 42 may be prevented from being separated from each other in the vertical direction by, for example, inserting bolts 30 into the bolt insertion holes 54, 70 at the four corners.

[0073] <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.

[0074] First, the circuit unit 10 manufactured as described above is placed on a predetermined position on the top surface 24 of the housing 12. For ease of understanding, although Figures 2 and 3 show the upper case 40 separated from the lower case 42, the circuit unit 10 is assembled to the housing 12 as a whole. At this time, the insulating sheets 64 and the elastic heat conductive members 66 are laminated and fixed to the heat dissipation portions 130 of the heat dissipation bus bars 128a to 128d, and the elastic heat conductive member 68 is fixed to the bottom wall portion 152 of the precharge resistor 22 (metal case 146). The circuit unit 10 is placed on the top surface 24 of the housing 12 so that the support protrusions 28 protruding from the top surface 24 fit into recesses formed by providing the mounting portions 72 on the bottom surface of the circuit unit 10 (bottom surface 74 of the lower case 42). This positions the circuit unit 10 and the housing 12 in the horizontal direction, and vertically communicates the bolt insertion holes 54, 70 at the four corners of the circuit unit 10 with the bolt fastening holes 32 in the support protrusions 28.

[0075] Then, by placing the circuit unit 10 on the top surface 24 of the housing 12, the fixed portions 34a, 34b protruding upward from the top surface 24 are inserted into the circuit unit 10 through the insertion holes 46a, 46b provided in the lower case 42. In particular, as described above, when the bottom surface of the circuit unit 10 (the bottom surface 74 of the lower case 42) and the top surface 24 of the housing 12 are placed together, the top surface of each fixed portion 34a protrudes upward beyond the protruding end surface 88 of each frame portion 78. As a result, when the bottom surface 74 of the circuit unit 10 and the top surface 24 of the housing 12 are placed together, the top surface of each fixed portion 34a abuts against the flange-like portions 158 of each metal case 146 from below, and each flange-like portion 158 (particularly, each held portion 166) is spaced upward from the protruding end surface 88 of the holding portion 76 (particularly, the support portion 84). As a result, the screw insertion holes 107 in each fixing portion 108, the screw insertion grooves 160 in each flange-shaped portion 158, and the screw fastening holes 38 in each fixed portion 34a are in vertical communication. Also, each fixed portion 34b abuts against each outward protruding portion 110 of the pressing part 16 from below, and the screw insertion holes 107 in each outward protruding portion 110 are in vertical communication with the screw fastening holes 38 in each fixed portion 34b.

[0076] In this state, bolts 30 are inserted into the bolt insertion holes 54, 70 at the four corners of the circuit unit 10 and fastened to the bolt fastening holes 32. Furthermore, screws 36 are inserted through the screw insertion holes 107 and the screw insertion grooves 160 in the upper case 40 and fastened to the screw fastening holes 38, thereby fixing the fixing portions 108 formed around the screw insertion holes 107 to the fixed portions 34a, 34b. As described above, the fixing portions 108 and the fixed portions 34a are fixed together with the flange-shaped portions 158 (mounting portions 164) sandwiched between them, i.e., together with the mounting portions 164. This completes the assembly of the circuit unit 10 to the housing 12.

[0077] When the circuit unit 10 is assembled to the housing 12, the pressing surface 106 of the pressing component 16 is in contact with the opposing surface 157 of the pre-charge resistor 22 (metal case 146) over substantially the entire surface. By fastening each fixing portion 108 and each fixed portion 34a, 34b with screws 36, the pressing component 16 is brought close to the housing 12, and the pressing component 16 presses the pre-charge resistor 22 against the elastic heat conductive member 68 and the housing 12 through the opening 44, without going through the case 14 (lower case 42). Furthermore, the heat dissipation portions 130 of the heat dissipation bus bars 128a-128d 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 154 of the pre-charge resistor 22 is in thermal contact with the housing 12 via the elastic heat conductive member 68. 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, 68 be slightly compressed in the vertical direction between each of the heat dissipation sections 130 and the thermal contact section 154 (lower wall section 152) and the housing 12.

[0078] As described above, the circuit unit 10 assembled inside the battery pack housing 12 has the connection portions 122a to 122d 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.

[0079] 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 132, 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 126. Therefore, when the vehicle is started, the pre-charge circuit 132 is energized, causing the pre-charge resistor 22 to heat up, and after the vehicle is started, the main circuit 126 is energized, causing the relays 18a and 18b to heat up. That is, the precharge resistor 22 and the positive relay 18a generate heat at different times.

[0080] On the other hand, the housing 12, with which the thermal contact portion 154 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.

[0081] 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 146, and heat can be dissipated through the metal case 146. 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.

[0082] Furthermore, the circuit unit 10 employs a pressing component 16 that presses the heat-generating component (pre-charge resistor 22), and with the circuit unit 10 fixed to the housing 12, the fixing portions 108 of the pressing component 16 are fixed to the fixing portions 34a, 34b of the housing 12, thereby causing the thermal contact portion 154 of the pre-charge resistor 22 to be pressed approximately evenly in the circumferential direction against the housing 12. This avoids the problem of the elastic heat conduction member 68 located between the thermal contact portion 154 (lower wall portion 152) and the housing 12 being partially suppressed in the circumferential direction, which would result in a deterioration in heat dissipation efficiency, and the pressing component 16 presses the pre-charge resistor 22 and the elastic heat conduction member 68 approximately evenly over their entirety, thereby achieving good heat dissipation performance.

[0083] In particular, the pressing surface 106 of the pressing component 16 is in contact over the entire surface with the opposing surface 157, which is the upper surface of the precharge resistor 22. As a result, by fixing the pressing component 16 to the housing 12, the pressing component 16 can press the entire precharge resistor 22, that is, the entire elastic heat conductive member 68 can be pressed against the housing 12. As a result, the heat dissipation performance of the circuit unit 10 can be more reliably improved.

[0084] The pressing component 16 is provided with fixing portions 108 at both ends in the longitudinal direction (front-rear direction) and with ribs 114 extending in the longitudinal direction. This suppresses deformation of the pressing component 16 and prevents localized compression of the elastic heat conducting member 68, even when the fixing portions 108 and the fixed portions 34a on both longitudinal sides are secured with screws 36 as in the first embodiment. This further improves the heat dissipation performance of the circuit unit 10. In particular, in the first embodiment, fixing portions 108 are also provided at both ends in the lateral direction (left-right direction) of the pressing component 16, and the fixing portions 108 are arranged at approximately equal intervals around the periphery of the pressing component 16. This allows the pre-charge resistor 22 and the elastic heat conducting member 68 to be pressed approximately evenly throughout, further improving the heat dissipation performance.

[0085] Furthermore, the provision of the rib 114 on the pressing part 16 makes it necessary to distinguish between the front and back (upper and lower) of the pressing part 16. However, by providing the positioning holes 112 (and the positioning bosses 98) at positions that are not symmetrical with respect to the lines L1 and L2 as in the first embodiment, incorrect assembly of the pressing part 16 in an upside-down state can be prevented. In particular, in the first embodiment, the pressing part 16 has a rotationally symmetric shape about a central axis extending in the up-down direction (a central axis extending in the up-down direction at the intersection of the lines L1 and L2). This allows the pressing part 16 to be assembled to the lower case 42 without having to specify the front-rear or left-right orientation of the pressing part 16. Furthermore, the positioning bosses 98 and the positioning holes 112 are provided at corresponding positions, allowing the pressing part 16 and the lower case 42 to be positioned relative to each other when assembling the pressing part 16 to the lower case 42.

[0086] 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 within case 14, is held by holding portion 76 provided on case 14, but when mounted to housing 12, pre-charge resistor 22 is separated from holding portion 76, and each mounting portion 164 of pre-charge resistor 22 is fixed directly to each fixed portion 34a, 34b of housing 12. This eliminates the need to consider tolerances in case 14, and ensures more reliable thermal contact between thermal contact portion 154 of pre-charge resistor 22 and housing 12.

[0087] That is, for example, in a conventional structure in which the precharge resistor is fixed to a case and the case is fixed to a 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 conduction member needs to be made thicker. 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 14, and therefore the elastic heat conduction member 68 can be made thinner, thereby improving heat conduction efficiency.

[0088] The retaining portion 76 includes a frame portion 78 that surrounds the opening window 44 and protrudes inward into the case 14. Before the circuit unit 10 is fixed to the housing 12, a retained portion 166 (flange-shaped portion 158) of the pre-charge resistor 22 that protrudes outward from the peripheral wall portion 148 is placed against a protruding end surface 88 of the frame portion 78. This prevents the pre-charge resistor 22 from being removed from the circuit unit 10 through the opening window 44. In particular, in the first embodiment, the frame portion 78 includes a pair of side walls 80, 80 that face each other in the left-right direction. When the pre-charge resistor 22 is held by the retaining portion 76, left-right displacement of the pre-charge resistor 22 is also suppressed. As a result, before the circuit unit 10 is fixed to the housing 12, displacement of the pre-charge resistor 22 within the case 14 is suppressed, preventing damage to the pre-charge resistor 22.

[0089] Furthermore, the holding portion 76 includes a flexible piece 90 having a locking claw 92 at its protruding tip, and when the precharge resistor 22 and the pressing component 16 are assembled to the holding portion 76, each locking claw 92 comes into contact with the base plate 104 of the pressing component 16, thereby preventing the precharge resistor 22 and the pressing component 16 from being pulled out upward from the holding portion 76. 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.

[0090] The mounting portions 164 of the precharge resistor 22 are located at the same vertical position as the held portions 166, and the fixed portions 34a, 34b of the housing 12 are positioned higher, beyond the protruding end surface 88 of the frame portion 78, when the circuit unit 10 is fixed to the housing 12. In the first embodiment, the mounting portions 164 and the held portions 166 of the precharge resistor 22 are both formed on the flange-shaped portions 158 of the metal case 146. 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 portion and the held portion are provided separately. Furthermore, the fixed portions 34a, 34b protrude upward from the top surface 24 of the housing 12, and screw fastening holes 38 are provided at the upper ends of the fixed portions 34a, 34b. This allows the refrigerant flow path 26 to be formed in the housing 12 without considering the position of the screw fastening holes 38.

[0091] <Modifications> Although the first embodiment has been described above in detail as a specific example of the present disclosure, the present disclosure is not limited to this specific description. 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 embodiment are also included in the technical scope of the present disclosure.

[0092] (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.

[0093] (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.

[0094] (3) In the above embodiment, the window 44 and the insertion holes 46a on both sides in the front-rear direction were formed in communication with each other in the bottom wall portion 60 of the lower case 42. However, the window and these insertion holes may be formed separately. Furthermore, the shape, size, number, etc. of the window and the insertion holes are not limited, and can be appropriately set depending on the heat-generating component, and the shape, size, number, etc. of the insertion holes can be appropriately set depending on the fixed portion provided on the heat dissipation target.

[0095] (4) In the above embodiment, 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 embodiment, the electric wires 136, 138 extending from the precharge resistor 22 extend from one end (front end) in the longitudinal direction of the precharge resistor 22. However, for example, two electric wires may extend from both ends in the longitudinal direction of the precharge resistor.

[0096] (5) In the above embodiment, the rib 114 is provided on the upper surface of the pressing component 16. However, as long as the pressing component can press the heat-generating component approximately evenly, a rib may be provided on the lower surface of the pressing component. Note that such a rib is not essential. Also, in the above embodiment, the positioning holes 112 are provided asymmetrically with respect to the lines L1 and L2. However, this is not a limitation. In other words, the pressing component may be configured to be mounted on the lower case in an inverted state, which improves manufacturing efficiency.

[0097] 10 Circuit unit 12 Housing (heat dissipation target) 14 Case 16 Pressing part 18 Relay 18a Positive side relay 18b Negative side relay 20 Pre-charge relay 22 Pre-charge resistor (heat-generating part) 24 Upper surface 26 Refrigerant flow path 28 Support protrusion 30 Bolt 32 Bolt fastening hole 34 Fixed part 34a (opposing in the front-rear direction) Fixed part 34b (opposing in the left-right direction) Fixed part 36 Screw 38 Screw fastening hole 40 Upper case 42 Lower case 44 Opening window 46 Insertion hole 46a (opposing in the front-rear direction) Insertion hole 46b (opposing in the left-right direction) Insertion hole 48 Upper bottom wall part 50 Upper peripheral wall part 52a to 52d Through window 54 Bolt insertion hole 56 Mounting part 58 Insertion hole 60 Bottom wall portion 62 Opening window 64 Insulating sheet 66, 68 Elastic heat conductive member 70 Bolt insertion hole 72 Mounting portion 74 Underside 76 Holding portion 78 Frame portion 80 Side wall portion 82 Bent portion 84 Support portion 86 Insertion window portion 88 Protruding end surface 90 Deflecting piece portion 92 Locking claw portion 94 Inclined surface 96 Gap 98 Positioning boss 100 Base portion 102 Pin-shaped portion 104 Base plate portion 106 Pressing surface 107 Screw insertion hole 108 Fixing portion 110 Outward protruding portion 112 Positioning hole 114 Rib 116 Terminal portion 118 Current-carrying bus bars 118a to 118d First to fourth current-carrying bus bars 120 Bolt 122a to 122d Connection portion 124 Bolt 126 Main circuit 128a to 128d First to fourth heat dissipation bus bars 130 Heat dissipation portion 132 Precharge circuit 134, 136, 138 Electric wire 140 Terminal 142 Screw 144 Terminal portion 146 Metal case 148 Peripheral wall portion 150 Upper wall portion 152 Lower wall portion 154 Thermal contact portion 156 Lower surface 157 Opposing surface (upper surface) 158 Flange-shaped portion 160 Screw insertion groove 164 Placement portion 166 Held portion L1, L2 Straight line

Claims

1. A circuit unit comprising a heat generating component, a case for housing the heat generating component, and a pressing component for pressing the heat generating component, wherein the heat generating component has a heat contact portion that is thermally in contact with a heat dissipation target via an elastic heat conducting member, and an opposing surface facing the heat contact portion; the case has an opening window for exposing the heat contact portion of the heat generating component to the outside, and an insertion hole into which a fixed portion provided on the heat dissipation target is inserted; the pressing component has a pressing surface that contacts the opposing surface of the heat generating component, and a fixed portion that is fixed to the fixed portion of the heat dissipation target; and in a state where the fixed portion is fixed to the fixed portion inserted into the insertion hole, the pressing surface of the pressing component contacts the opposing surface of the heat generating component, and the pressing component fixed to the heat dissipation target presses the heat generating component against the elastic heat conducting member without passing through the case.

2. The circuit unit according to claim 1, wherein the pressing surface of the pressing component contacts the entire opposing surface of the heat generating component.

3. The circuit unit according to claim 1 or 2, wherein the pressing surface of the pressing component extends in a rectangular shape, the pressing component has the fixed portions provided on both end sides in the longitudinal direction of the pressing surface, and ribs extending in the longitudinal direction project from the pressing component.

4. The case has a holding portion that projects inside the case and engages with the heat generating component to hold the heat generating component in the case; the heat generating component has a mounting portion that is placed on the fixed portion and fixed to the fixed portion together with the fixed portion; and by fixing the mounting portion of the heat generating component to the fixed portion, the heat generating component is separated from the holding portion. The circuit unit according to claim 1 or 2.

5. The circuit unit according to claim 4, wherein the holding portion includes a frame portion that surrounds the periphery of the opening window and projects inward of the case, and a held portion projecting from the peripheral wall portion of the heat generating component is placed on the projecting end surface of the frame portion.

6. The holding portion protrudes inward of the case from the frame portion and includes a bending piece portion that can be elastically deformed on the outer peripheral side of the opening window. The bending piece portion has a locking claw portion provided at the protruding tip and protruding toward the inner peripheral side of the opening window. When the bending piece portion is elastically deformed toward the outer peripheral side, the assembly of the heat generating component and the pressing component onto the frame portion is allowed. With the held portion of the heat generating component placed on the protruding end face of the frame portion, the locking claw portion of the elastically restored bending piece portion overlaps the pressing component with a gap in the protruding direction of the frame portion. The circuit unit according to claim 5.

7. In a state where it is fixed to the heat dissipation target, the fixed portion of the heat dissipation target is arranged inward of the case beyond the protruding end face of the frame portion in the protruding direction of the frame portion. The circuit unit according to claim 5.

8. The case has positioning bosses arranged at a plurality of locations around the opening window and protruding beyond the fixing portion. The pressing component has a plurality of positioning holes penetrating therethrough at positions corresponding to the positioning bosses and through which the positioning bosses are inserted. The circuit unit according to claim 1 or claim 2.

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