JP2025107671A - Circuit Unit - Google Patents

Abstract

To disclose a circuit unit capable of suppressing a compression state of an elastic heat conduction member interposed between a heat-generating component and a heat dissipation target from being uneven, thereby suppressing deterioration of cooling performance caused by an increase in the partial thermal resistance of the elastic heat conduction member.SOLUTION: 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 portion 154 that is thermal contact with a heat dissipation target 12 via an elastic heat-conducting member 68. The case 14 has an opening window 44 that exposes the thermal contact portion 154 to the outside, and an insertion hole 46 into which a fixed portion 34 provided on the heat dissipation target 12 is inserted. A pressing component 16 has a fixing portion 108 to be fixed to a fixed portion 34 of the heat dissipation target 12. In a state where a fixing portion 108 is fixed to the fixed portion 34 inserted into the insertion hole 46, the pressing component 16 contacts the heat-generating component 22, and the pressing component 16 fixed to the heat dissipation target 12 presses the heat-generating component 22 against the elastic heat-conducting member 68 without interposing the case 14 therebetween.SELECTED DRAWING: Figure 5

Description

This disclosure relates to a circuit unit.

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 pre-charge resistors, which are ceramic resistors, in a case. In order to promote heat dissipation from such heat-generating components, the circuit unit of Patent Document 1 employs a structure in which the thermal contact parts of the heat-generating components fixed to the case are brought into contact with the metal outer housing, which is the heat dissipation target, via an elastic heat-conducting sheet, thereby ensuring a heat dissipation path for the heat-generating components.

JP 2009-181737 A

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 cannot sufficiently compress the central portion of the heat-generating component that 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 will increase in that portion, causing a deterioration in cooling performance.

Therefore, we disclose a circuit unit that can prevent the compression state of the elastic heat conductive 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 partial thermal resistance of the elastic heat conductive member.

The circuit unit of the present disclosure includes a heat generating component, a case that houses the heat generating component, and a pressing component that presses the heat generating component. The heat generating component has a thermal contact portion that thermally contacts a heat dissipation target via an elastic heat conductive 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. With the fixing portion 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 conductive member without going through the case.

The circuit unit disclosed herein can prevent the elastic heat conductive member located between the heat generating component and the heat dissipation target from becoming unevenly compressed, thereby preventing an increase in the partial thermal resistance of the elastic heat conductive member.

FIG. 1 is a perspective view showing a circuit unit according to a first embodiment in a state where the circuit unit is 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 a case removed. 3 is a plan view showing the circuit unit shown in FIG. 2 with the upper case removed. FIG. FIG. 4 is an enlarged longitudinal sectional view showing a main part taken along line IV-IV in FIG. FIG. 5 is an enlarged longitudinal sectional view showing a main part taken along the line VV in FIG. FIG. 6 is an exploded perspective view of the circuit unit shown in FIG. FIG. 7 is a plan view showing a lower case constituting the circuit unit shown in FIG. FIG. 8 is a perspective view showing the circuit unit shown in FIG. 1 in a state before it is fixed to a heat dissipation target, with the upper case removed. FIG. 9 is a vertical cross-sectional view of the circuit unit shown in FIG. 8 and corresponds to FIG.

<Description of the embodiments of the present disclosure>
First, embodiments of the present disclosure will be listed and described.
The circuit unit of the present disclosure includes:
(1) A heat generating component, a case for accommodating the heat generating component, and a pressing part for pressing 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 conductive member, and an opposing surface that faces the thermal contact portion, the case has an opening window for exposing 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 part has a pressing surface that contacts the opposing surface of the heat generating component and a fixing part that is fixed to the fixed portion of the heat dissipation target, and with the fixing part fixed to the fixed portion inserted into the insertion hole, the pressing surface of the pressing part contacts the opposing surface of the heat generating component, and the pressing part fixed to the heat dissipation target presses the heat generating component against the elastic heat conductive member without going through the case.

According to the circuit unit of this aspect, the thermal contact portion of the heat-generating component housed in the case can be exposed from the opening window of the case and can be brought into contact with the heat dissipation target via the elastic heat conductive member. In this case, a pressing part separate from the heat-generating component and the case is used, and the fixing part of the pressing part is fixed to the fixed part of the heat dissipation target inserted into the insertion hole of the case, so that the pressing surface of the pressing part is brought into contact with the opposing surface of the heat-generating component, and the heat-generating component can be pressed against the elastic heat conductive member by the pressing surface of the pressing part fixed directly to the heat dissipation target without going through the case. This makes it possible to prevent the compression state of the elastic heat conductive member interposed between the heat-generating component and the heat dissipation target from becoming uneven, compared to the case in which the heat-generating component fixed to the case is pressed against the heat dissipation member side through the case as in the conventional structure. As a result, it is possible to provide a circuit unit that can prevent the occurrence of an increase in partial thermal resistance of the elastic heat conductive member and the resulting deterioration of cooling performance.

The number of fixing parts of the pressing part and the fixed parts of the heat dissipation target can be set arbitrarily according to the shape of the opposing surface of the heat generating part. For example, if the opposing surface is annular, one fixing part can be provided in the center of the pressing part and fixed to one fixed part arranged at the opposing location, which can prevent the elastic heat conducting member from being compressed unevenly. If the opposing surface of the heat generating part is circular, elliptical, rectangular, etc., multiple fixing parts can be provided on the pressing part at multiple locations spaced apart from each other in the circumferential direction around the heat generating part, and the pressing part can be fixed to multiple fixed parts arranged at locations opposite the multiple fixing parts, which can advantageously prevent the elastic heat conducting member from being compressed unevenly.

(2) In the above (1), it is preferable that the pressing surface of the pressing part is in contact with the entire surface of the opposing surface of the heat generating part. By pressing the entire surface of the opposing surface of the heat generating part with the pressing surface of the pressing part, the compression state of the elastic heat conducting member can be made more uniform, and the occurrence of an uneven compression state and the resulting increase in partial thermal resistance and deterioration of cooling performance can be more effectively prevented.

(3) In the above (1) or (2), it is preferable that the pressing surface of the pressing part expands in a rectangular shape, the pressing part has the fixing parts provided on both ends of the pressing surface in the longitudinal direction, and the pressing part has a protruding rib extending in the longitudinal direction. Since the fixing parts of the pressing part are provided on both ends of the pressing surface in the longitudinal direction, it becomes easy to apply the pressing force from the pressing surface evenly to the heat-generating component. Moreover, since the pressing part has a rib extending in the longitudinal direction between the fixing parts to which a fixed load is applied to the heat dissipation target, deformation of the pressing surface of the pressing part can be prevented, and the occurrence of an uneven compression state can be more advantageously suppressed.

(4) In any one of the above (1) to (3), it is preferable that the case has a holding portion that protrudes from the inside of the case and engages with the heat-generating component to hold the heat-generating component in the case, the heat-generating component has a placement portion that is 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 placement portion of the heat-generating component to the fixed portion. Since the case is provided with a holding portion that engages with the heat-generating component to hold the heat-generating component in the case, before the circuit unit is fixed to the heat dissipation target, the heat-generating component can be advantageously prevented from escaping from the inside of the case to the outside through the opening window due to the engagement of the heat-generating component with the holding portion. In addition, in a state in which the pressing component of the circuit unit is fixed to the fixed portion of the heat dissipation target, the placement portion of the heat-generating component is fixed to the fixed portion together with the fixing portion, so that the heat-generating component can be separated from the holding portion. As a result, even if the case has a holding portion, a state in which the heat-generating component is pressed against the heat dissipation target by the pressing component without going through the case can be realized. As a result, it is possible to achieve both improved assembly workability of the circuit unit and stable cooling performance.

(5) In the above (4), it is preferable that the holding portion includes a frame portion surrounding the periphery of the opening window and protruding inwardly 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. Since the holding 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 members. Furthermore, since the held portion protruding from the peripheral wall portion of the heat-generating component is placed on the protruding end surface of the frame portion, it is possible to reliably prevent the heat-generating component 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 it is fixed to the fixed portion of the heat dissipation target.

(6) In the above (5), 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 and protruding toward the inner periphery of the opening window, the flexible piece portion is flexible and deformed 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 portion of the flexible piece portion that has elastically returned overlaps the pressing component with a gap in the protruding direction of the frame body portion when the held portion of the heat-generating component is placed on the protruding end surface of the frame body portion. The holding portion further includes a flexible piece portion in addition to the frame body portion, and the locking claw portion provided at the protruding tip of the flexible piece portion overlaps the pressing component placed on the protruding end surface of the frame body portion via the heat-generating component with a gap in the protruding direction of the frame body portion. This allows the heat generating component and the pressing component to be prevented from popping out of the opening window, as well as from being displaced in the opposite direction, by engaging with the locking claws, allowing the heat generating component and the pressing component to be held more stably within the case.

(7) In the above (5) or (6), it is preferable that, in a state where the heat dissipation target is fixed, the fixed portion of the heat dissipation target is arranged to be disposed inside the case beyond the protruding end face of the frame body part in the protruding direction of the frame body part. In the protruding direction of the frame body part, the fixed portion of the heat dissipation target is arranged to be disposed inside the case beyond the protruding end face of the frame body part. In this way, by fixing the placement portion of the heat-generating component together with the fixing portion of the pressing component to the fixed portion, the heat-generating component can be separated from the holding portion (frame body part), and the fixing portion of the heat-generating component can be directly fixed to the fixed portion of the heat dissipation target.

(8) In any one of the above (1) to (7), 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 provided 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 the front and back of the pressing part, such as when a rib is provided on the pressing part as in the above embodiment (3), the positioning bosses and the positioning holes can be positioned at asymmetric positions on the pressing part, thereby preventing erroneous assembly of the front and back of the pressing part. In addition, by making the shape of the pressing part, including not only the positioning bosses and the positioning holes but also the fixing portion, a rotational symmetric shape around the central axis can be used to more easily position the pressing part relative to the case, without the need to distinguish, for example, the front-rear and/or left-right directions of the pressing part.

<Details of the embodiment 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 of the claims.

<Embodiment 1>
Hereinafter, a circuit unit 10 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 to 9. The circuit unit 10 is mounted on, for example, an electric vehicle or a hybrid vehicle, and is connected between an on-board power source (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 precharge resistor 22 described later), and heat generated in the heat-generating component due to energization is dissipated through a heat dissipation target (a housing 12 described later) to which the circuit unit 10 is fixed. Note that the circuit unit 10 can be arranged in any direction in the vehicle, but in the following, the upper side will be described 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, for multiple identical members, only some of the members may be labeled with a reference symbol, and the reference symbols may be omitted for the other members.

<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. 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, but in the first embodiment, the structure of the present disclosure is applied to the precharge resistor 22 among the electrical components, and therefore the heat generating component is constituted by the precharge resistor 22. In the first embodiment, not only the precharge resistor 22 but also the relay 18 and the precharge relay 20 are housed and held within the case 14.

<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, and the circuit unit 10 and the battery are housed in the housing 12 to form a battery pack (not shown). That is, the circuit unit 10 is stacked and fixed on the upper surface 24 of the housing 12, and heat generated by energizing the electrical components provided in the circuit unit 10 is dissipated through the housing 12. Therefore, in the first embodiment, the heat dissipation target from which the heat generated in the circuit unit 10 is dissipated is constituted by the metal housing 12. In addition, in the figure, a flat metal plate constituting the bottom wall of the housing 12 is shown, and as shown in FIG. 1, for example, a refrigerant flow path 26 may be formed inside the metal plate. A known refrigerant is used as the refrigerant flowing through the refrigerant flow path 26. In addition, the extending direction and length of the refrigerant flow path 26 shown in FIG. 1 are merely exemplary, and the extending direction and length of the refrigerant flow path are not limited.

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

In the first embodiment, a pair of fixed parts 34a, 34a face each other at a predetermined distance in the front-rear direction, and another pair of fixed parts 34b, 34b face each other at a predetermined distance in the left-right direction, so that a total of four fixed parts 34a, 34b are provided in the housing 12. In particular, in the first embodiment, each fixed part 34b is provided at the center of the front-rear direction of each fixed part 34a, and each fixed part 34a is provided at the center of the left-right direction of each fixed part 34b. That is, each fixed part 34a, 34b is arranged at a position that is rotationally symmetrical about a central axis extending in the up-down direction through the center of each fixed part 34a, 34b. Each of these fixed parts 34a, 34b is generally prism-shaped, and as shown in FIG. 5, each fixed part 34a has a protruding dimension B from the upper surface 24 of the housing 12, and each fixed part 34b has a protruding dimension B' that is slightly larger than the protruding dimension B. At the upper end of each fixed portion 34a, 34b, a screw fastening hole 38 is formed into which a screw 36 is fastened to fasten each mounting portion 164 to each fixed portion 34a, 34b.

<Case 14>
As described above, the circuit unit 10 has a case 14 that holds the relay 18 (positive and negative relays 18a, 18b described later), the precharge relay 20, and the precharge resistor 22. In the first embodiment, the case 14 is a hollow rectangular parallelepiped as a whole, and the left-right dimension is 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 to each other in the vertical direction. The upper case 40 and the lower case 42 are formed of, for example, a synthetic resin. Although the method of fixing the upper case 40 and the lower case 42 is not limited, in the first embodiment, the above-mentioned bolts 30 are inserted at the four corners of the circuit unit 10 in a state where the upper case 40 and the lower case 42 are overlapped, and are fastened to the bolt fastening holes 32 provided in each support protrusion 28 of the housing 12, thereby fixing the upper case 40 and the lower case 42 to each other.

The case 14 also has an opening window 44 that exposes the thermal contact portion 154 (described later) of the heat generating component (precharge resistor 22) to the outside, and an insertion hole 46 into which the fixed portions 34a, 34b provided on the heat dissipation target (housing 12) are inserted. Both the opening window 44 and the insertion holes 46 are provided in the lower case 42. In the first embodiment, since four fixed portions 34a, 34b are provided, 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, each insertion hole 46a, 46b is also arranged in a position that is rotationally symmetrical about a central axis that extends vertically through the center of each insertion hole 46a, 46b.

<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. The upper bottom wall 48 is provided with rectangular through-windows 52a-52d that penetrate in the thickness direction (vertical direction) at positions corresponding to the respective connection portions 122a-122d of the first to fourth current-carrying bus bars 118a-118d described below when the circuit unit 10 is in an assembled state. Mounting portions 56 having bolt insertion holes 54 are provided at the four corners around 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.

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

In the bottom wall 60, rectangular opening windows 62 are provided at positions corresponding to the heat dissipation sections 130 of the first to fourth heat dissipation bus bars 128a to 128d described later when the circuit unit 10 is assembled. In addition, in the bottom wall 60, the above-mentioned opening window 44 is provided at positions corresponding to the thermal contact section 154 (lower wall section 152 of the metal case 146) described later of the precharge resistor 22 (metal clad resistor) when the circuit unit 10 is assembled, which penetrates in the thickness direction (upper and lower direction). In the first embodiment, the opening window 44 is rectangular and has a larger area in plan view than the lower surface 156 of the precharge resistor 22 described later. As a result, the opening window 44 exposes the thermal contact section 154 (lower wall section 152) of the metal case 146 so that it can thermally contact the housing 12 when the circuit unit 10 is assembled.

In addition, the above-mentioned insertion holes 46a, 46b into which the fixed parts 34a, 34b of the housing 12 are inserted are formed on both sides of the opening window 44 in the front-rear direction and on both sides of the left-right direction. Each of these insertion holes 46a, 46b has a substantially rectangular shape. In the first embodiment, the opening window 44 and each of the insertion holes 46a on both sides of the front-rear direction are connected to each other, and each of the insertion holes 46a is connected to each other on both sides of the front-rear direction on the inner peripheral surface of the opening window 44 in the front-rear direction. In addition, the opening window 44 and each of the insertion holes 46b on both sides of the left-right direction are formed independently of each other, and each of the insertion holes 46b is formed at a predetermined distance from the opening window 44 in the left-right direction.

In the first embodiment, when the circuit unit 10 is fixed to the housing 12, an insulating sheet 64 and an elastic heat conductive member 66 are housed in a laminated state in each opening window 62 provided below each heat dissipation section 130. As a result, each heat dissipation section 130 in the first to fourth heat dissipation bus bars 128a to 128d is in contact with the housing 12, which is overlapped with the bottom wall section 60, in an electrically insulated state and in a thermally conductive state. Note that the insulating sheet 64 and the elastic heat conductive member 66 do not need to be separate members, and may be composed of a single member having insulating properties and thermal conductivity. The insulating sheet 64 and the elastic heat conductive member 66 are fixed (for example, glued) to the lower surface of each heat dissipation section 130 when the circuit unit 10 is fixed to the housing 12, and as shown in FIG. 4, when the circuit unit 10 is fixed to the housing 12, each insulating sheet 64 and each elastic heat conductive member 66 are arranged in a housed state inside each opening window 62. The insulating sheet 64 and the elastic heat conductive member 66 may be made of known materials, and the elastic heat conductive member 66 may be made of, for example, a heat conductive sheet or gap filler with good thermal conductivity.

In addition, when the circuit unit 10 is fixed to the housing 12, an elastic heat conductive member 68 is accommodated in the opening window 44 provided below the thermal contact portion 154 of the precharge resistor 22. As a result, the thermal contact portion 154 is in contact with the housing 12 in a thermally conductive state. Since the winding resistor constituting the precharge resistor 22 is accommodated in the metal case 146 described later in an insulated state, even when the circuit unit 10 is in a conductive state, the metal case 146 is in an electrically insulated state, and the insulating sheet 64 does not need to be arranged in the opening window 44. For example, when the circuit unit 10 is fixed to the housing 12, the elastic heat conductive member 68 is fixed (for example, glued) to the lower surface 156 of the thermal contact portion 154 (the lower wall portion 152 of the metal case 146), and when the circuit unit 10 is fixed to the housing 12, the elastic heat conductive member 68 is arranged in a accommodated state inside the opening window 44. The elastic heat conductive member 68 may be made of the same material as the elastic heat conductive member 66 provided below the relay 18 (the positive and negative relays 18a and 18b described below). Each of these elastic heat conductive members 66 and 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 when exposed to heat or light.

Furthermore, mounting parts 72 having bolt insertion holes 70 are provided at the four corners of the periphery of the lower case 42 (bottom wall part 60), and each mounting part 72 is located somewhat higher than the other parts of the bottom wall part 60. In other words, a recess is formed at the four corners of the periphery of the underside 74 of the lower case 42, which is recessed upward relative to the other parts. In this way, the mounting parts 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, and corresponding concave and convex shapes are provided. As a result, when the upper case 40 and the lower case 42 are stacked in the vertical direction, 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.

<Holding part 76>
The case 14 has a holding portion 76 that protrudes into the case 14 and engages with the heat-generating component (pre-charge resistor 22) to hold the pre-charge resistor 22 in the case 14. In the first embodiment, the lower case 42 has the holding portion 76, and the holding portion 76 protrudes upward into the case 14. The holding portion 76 also includes a frame portion 78 that surrounds the periphery of the opening window 44 and protrudes upward into the case 14. That is, the protruding direction of the frame portion 78 is the up-down direction (particularly, the direction from the bottom to the top). Specifically, the frame portion 78 has a pair of side wall portions 80, 80 that extend in the front-rear direction at both left-right side edges of the opening window 44, and each of these side wall portions 80 has a front-rear dimension larger than that of the opening window 44. Both front-rear end portions of each side wall portion 80 are bent in a crank shape, and both front-rear end portions of each side wall portion 80 are located laterally inward from the front-rear intermediate portion via bent portions 82. These both 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 pre-charge resistor 22 are placed and supported.

Each support portion 84 is located outward in the front-rear direction from the opening window 44, and in the first embodiment, since each insertion hole 46a is formed to be connected to both front-rear end portions of the opening window 44, 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, an insertion window portion 86 penetrating in the front-rear direction is provided between the opposing support portions 84, and each insertion window portion 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, but depending on the wiring mode of the precharge circuit 132, which will be described later, each of the electric wires 136, 138 may extend to the outside through the rear insertion window portion 86.

More specifically, the flange-like portions 158 (particularly the held portions 166, which are the left-right end portions) of the 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 body portion 78, i.e., the protruding end surfaces 88 of each support portion 84. That is, the flange-like portions 158 of the metal case 146 of the precharge resistor 22 are placed on the support portions 84 of the holding portion 76 as a form of engagement, so that the precharge resistor 22 is held by the holding portion 76. In this state, the peripheral wall portions 148 of the metal case 146 described later are housed between the side wall portions 80 of the frame body portion 78.

Here, the upward protrusion dimension A (the vertical dimension from the top surface of the bottom wall 60 to the protruding end surface 88) of the frame body 78 (see Figs. 5 and 9) is smaller than the upward protrusion dimension B (the vertical dimension from the top surface 24 of the housing 12 to the top surface of each fixed part 34a, 34b) (see Fig. 5) of each fixed part 34a, 34b provided on the housing 12. In particular, as described below, when the circuit unit 10 is fixed to the housing 12, each fixed part 34a, 34b protrudes into the inside of the circuit unit 10 through each insertion hole 46a, 46b of the lower case 42, and each fixed part 34a, 34b is disposed inside (above) the case 14 beyond the protruding end surface 88 in the protruding direction (vertical direction) of the frame body 78. In other words, when the circuit unit 10 is fixed to the housing 12, the upper surfaces of the fixed portions 34a and 34b are positioned above the protruding end surface 88 of the frame portion 78.

<Flexible piece 90>
The holding portion 76 also includes a flexible piece 90 that protrudes upward, more inwardly of the case 14 than the frame portion 78, and is capable of flexible deformation (elastic deformation in the first embodiment) on the outer circumferential side of the opening window 44. In the first embodiment, the flexible piece 90 is provided in a middle portion in the front-rear direction of each side wall portion 80, and in the first embodiment in particular, a pair of flexible pieces 90, 90 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 80. Thus, in the first embodiment, a total of four flexible pieces 90 are provided in the holding portion 76.

Each of the flexible pieces 90 has a lock 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 precharge resistor 22 and the pressing part 16 are assembled to the lower case 42, each of the lock claws 92 protrudes inward in the left-right direction to a position where it overlaps in the up-down direction with a base plate part 104 (described later) of the pressing part 16. In other words, when the precharge resistor 22 and the pressing part 16 are assembled to the lower case 42, the protruding tip (inner end in the left-right direction) of each of the lock claws 92 overlaps with both left-right side edges of the base plate part 104 in the plan view. In the first embodiment, the pressing part 16 and the precharge resistor 22 have substantially the same planar shape, and when projected in the plan view, the protruding tip of each of the lock claws 92 also overlaps with the precharge resistor 22 (the upper wall part 150 of the metal case 146 (described later)). However, this is not limited to this embodiment. That is, each lock claw portion 92 and the precharge resistor 22 (upper wall portion 150) do not have to overlap when projected in a plan view.

The upper surface of each locking claw portion 92 is provided with an inclined surface 94 that gradually slopes downward as it approaches the left-right direction inward. As a result, when the precharge resistor 22 is assembled to the holding portion 76, the precharge resistor 22 is brought close to the holding portion 76 from above, so that both left-right side edges of the lower surface 156 of the metal case 146 described later come into contact with the inclined surfaces 94 of each locking claw portion 92, elastically deforming each flexible piece portion 90 outward in the left-right direction. This allows the precharge resistor 22 to be assembled to the frame portion 78. Also, a pressing part 16 is assembled to the holding portion 76 (frame portion 78) from above the precharge resistor 22 in the same manner as the precharge resistor 22. When each flange-shaped 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 deforms (restores) so that, as shown in FIG. 9 and other figures, 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 portion 78.

<Positioning boss 98>
The case 14 has positioning bosses 98 that are arranged at a plurality of locations around the opening window 44 opposite to the pre-charge resistor 22 and that protrude beyond a fixing portion 108 (described later) of the pressing part 16. In the first embodiment, the positioning boss 98 is provided on the lower case 42, and is provided adjacent to a pair of side wall portions 80, 80 that face each other in the left-right direction, on the left-right outward side, as shown in Fig. 7 and other figures. That is, in the first embodiment, a pair of positioning bosses 98, 98 is provided on the lower case 42, and one (right) positioning boss 98 is provided rearward of the right insertion hole 46b, and the other (left) positioning boss 98 is provided in front of the left insertion hole 46b. In particular, in embodiment 1, since each insertion hole 46a, 46b is provided on both the front-to-rear and left-to-right sides of the opening window 44, each of these insertion holes 46a, 46b and each positioning boss 98 is formed in a position that is rotationally symmetrical 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.

More specifically, each positioning boss 98 has a base 100 having a generally rectangular parallelepiped outer shape, and a pin-shaped portion 102 that protrudes upward from the center of the base 100 on the upper end surface of the base 100. Each of these 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 of the pin-shaped portions 102 is located above a fixing portion 108 of the pressing part 16, which will be described later.

<Pressing part 16>
As shown in Figures 5 and 6, the pressing part 16 is generally rectangular and flat, and in the first embodiment, it is made of a metal having a relatively large deformation rigidity. That is, the pressing part 16 has a base plate part 104 that is substantially rectangular in plan view, and when the pressing part 16 is assembled to the lower case 42, the pressing part 16 (base plate part 104) extends in the front-rear direction. The pressing part 16 is placed over the heat generating part (pre-charge resistor 22) from above to press the pre-charge resistor 22, and the lower surface of the pressing part 16 (base plate part 104) is a pressing surface 106 that contacts the upper surface (opposing surface 157 described later) of the pre-charge resistor 22. In short, the pressing surface 106 spreads in a substantially rectangular shape in plan view.

This base plate portion 104 has a predetermined front-rear dimension and left-right dimension, and the longitudinal direction is the front-rear direction. Specifically, the base plate portion 104 has a front-rear dimension and left-right dimension that are approximately equal to the upper wall portion 150 of the precharge resistor 22, which will be described later. That is, in the first embodiment, the entire lower surface of the base plate portion 104 is a pressing surface 106 that contacts the opposing surface 157 of the precharge resistor 22, and the pressing surface 106 is configured to contact the entire opposing surface 157.

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

In addition, 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 mutually identical in shape and have a predetermined front-rear dimension and left-right dimension. Specifically, in a plan view of the state in which the pressing part 16 is assembled to the lower case 42, each outward protrusion 110 is arranged to overlap with each insertion hole 46b and each positioning boss 98 on both the left and right sides provided in the lower case 42. In addition, in the center of the front-rear direction of each outward protrusion 110, a screw insertion hole 107 is formed at a position corresponding to the screw fastening hole 38 in each fixed portion 34b. Furthermore, at a position corresponding to the pin-shaped portion 102 in each positioning boss 98 at the end of the front-rear direction of each outward protrusion 110, a positioning hole 112 through which each pin-shaped portion 102 is inserted is formed penetrating each outward protrusion 110.

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

These outward protrusions 110 are formed so that they are positioned between the respective flexible pieces 90 in the retaining portion 76 in the front-rear direction when the pressing part 16 is assembled to the lower case 42, so that the outward protrusions 110 and the respective flexible pieces 90 do not interfere with each other when the pressing part 16 is assembled to the lower case 42.

Furthermore, in the first embodiment, a rib 114 extending in the longitudinal direction (front-rear direction) of the pressing part 16 is provided on the surface (upper surface) of the base plate part 104 opposite the pressing surface 106, and protrudes upward. This rib 114 extends with a predetermined front-rear dimension at the center of the left-right direction of the pressing part 16 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 by the screws 36 as described below.

The pressing part 16 has a shape that is rotationally symmetrical about a central axis that extends in the vertical direction through the center of the base plate part 104 (the intersection of the diagonals of the rectangular base plate part 104). For example, the pressing part 16 shown in FIG. 3 can be assembled to the lower case 42 even when rotated 180 degrees around the central axis. On the other hand, the pressing part 16 has a shape that is not linearly symmetrical about a line L1 that extends in the front-rear direction through the center in the left-right direction and a line L2 that extends in the left-right direction through the center in the front-rear direction. This makes it impossible to assemble the pressing part 16 shown in FIG. 3 to the lower case 42 by turning it over (upside down). Therefore, by making the pressing part 16 have the above-mentioned shape, it is possible to reliably prevent erroneous assembly in a front-rear or left-right state, while eliminating the need to distinguish between the front-rear direction and the left-right direction, and the pressing part 16 can be more easily assembled to the lower case 42.

<Relay 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 the front side (the positive relay 18a is in the front, and the negative relay 18b is in 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.

Each terminal 116 is an input and output terminal for each relay 18a, 18b. 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.

A current-carrying bus bar 118 is overlapped on each terminal portion 116 of each of these relays 18a, 18b and fixed by a bolt 120. That is, the circuit unit 10 includes first and second current-carrying bus bars 118a, 118b connected to the input and output terminal portions 116, 116 of the positive relay 18a, and third and fourth current-carrying bus bars 118c, 118d connected to the input and output terminal portions 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 form input and output connection parts 122a, 122b on the positive electrode side, and input and output connection parts 122c, 122d on the negative electrode side.

The input connection part 122a on the positive side and the input connection part 122c on the negative side are electrically connected to the positive and negative terminal parts of a battery (not shown) by conductive members such as bus bars and wires. The output connection part 122b on the positive side and the output connection part 122d on the negative side are electrically connected to the positive and negative terminal parts of an inverter (not shown) by conductive members. Each of these connections 122a to 122d and the conductive members can be fixed by bolts 124.

As a result, a main circuit 126 between the battery and the inverter is formed, including each of the relays 18a, 18b, the first to fourth current-carrying bus bars 118a to 118d, and each of the above-mentioned conductive members. In this main circuit 126, by switching each of the relays 18a, 18b between ON and OFF, the main circuit 126 between the battery and the inverter can be switched between a current-carrying state and a current-dead state.

In addition to the first to fourth current bus bars 118a to 118d, the first to fourth heat dissipation bus bars 128a to 128d are fastened to the terminals 116 of the positive and negative relays 18a, 18b by bolts 120. The first to fourth heat dissipation bus bars 128a to 128d are each substantially L-shaped, with a portion extending in the vertical direction and a portion that bends from the lower end of the portion extending in the vertical direction and spreads in the horizontal direction (a direction perpendicular to the vertical direction). The upper end portions of the heat dissipation 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-rear direction and are located below the relays 18a, 18b.

The heat dissipation section 130 is formed by the portions extending in the front-rear direction at the lower end of each of these heat dissipation bus bars 128a-128d, and each heat dissipation section 130 is in thermal contact with the housing 12, which is the heat dissipation target, via the aforementioned insulating sheet 64 and 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-128d, the insulating sheet 64, and the elastic heat conductive member 66, and heat generated when electricity is applied to each relay 18a, 18b can be dissipated from the housing 12.

<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.

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

<Precharge relay 20>
A known precharge relay 20 may be used, and the structure is not limited thereto. The precharge relay 20 has 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 precharge relay 20 is arranged with the upper side facing forward, and each terminal 144 is exposed on the upper surface of the precharge relay 20. A terminal 140 provided at an end of an electric wire 134 connecting the positive relay 18a and the precharge relay 20 is overlapped with an input terminal 144 (left terminal 144) of the precharge relay 20 and fixed by a screw 142. A terminal 140 provided at an end of an electric wire 138 connecting the precharge relay 20 and the precharge resistor 22 is overlapped with an output terminal 144 (right terminal 144) of the precharge relay 20 and fixed by a screw 142.

<Precharge resistor 22>
The precharge resistor 22 is configured using a metal clad resistor. Since a known one can be used as the precharge resistor 22 (metal clad resistor), detailed description will be omitted, but a wire-wound resistor (not shown) is sealed in a metal case 146 in an insulated state. In the cross-sectional views of FIG. 5 and the like, illustration of the internal structure of the precharge resistor 22 is omitted, and only the metal case 146 is shown. In other words, the metal case 146 in the precharge resistor 22 is hollow, and a wire-wound resistor (not shown) is housed in an insulated state inside the metal case 146. In the first embodiment, the metal case 146 in the precharge resistor 22 is hollow and approximately rectangular, and is disposed in a direction extending in the front-rear direction. That is, the metal case 146 is configured to include a substantially cylindrical peripheral wall portion 148 including walls on both sides in the front-rear direction and both sides in the left-right direction, an upper wall portion 150 covering an upper opening of the peripheral wall portion 148, and a lower wall portion 152 covering a lower opening of the peripheral wall portion 148.

The metal case 146 of this precharge resistor 22 (metal clad resistor) has a thermal contact portion 154 that thermally contacts the housing 12 as a heat dissipation target. In the first embodiment, in a state where the circuit unit 10 described later is fixed to the housing 12, the metal case 146 is superimposed on the housing 12 via an elastic heat conductive member 68 superimposed on the lower surface (lower surface of the lower wall portion 152) 156 of the precharge resistor 22, and the thermal contact portion 154 is formed by the lower wall portion 152 that constitutes the hollow metal case 146. And, since the thermal contact portion 154 is formed by the lower wall portion 152 of the metal case 146, the opposing surface 157 that faces the thermal contact portion 154 of the metal case 146 is formed by the upper surface (upper surface of the upper wall portion 150) of the precharge resistor 22.

In particular, in the first embodiment, flange-like portions 158 are provided at the upper end (or upper wall portion 150) of the peripheral wall portion 148 of the metal case 146, protruding on both sides in the front-rear direction. 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 fixes the precharge resistor 22 is inserted. Due to the provision of each of these flange-like portions 158, the upper surface (opposing surface) 157 of the precharge resistor 22 has a larger area than the lower surface 156 of the precharge resistor 22 when projected in the vertical direction.

As described later, each flange-shaped portion 158 is placed on each fixed portion 34a of the housing 12, and each screw 36 is inserted into the screw insertion groove 160 and fastened to the screw fastening hole 38, so that the mounting portion 164 of the heat-generating component (pre-charge resistor 22) is fixed to the fixed portion 34a. Therefore, the mounting portion 164 is formed by the portion surrounding the screw insertion groove 160 in each flange-shaped portion 158 (the central portion in the left-right direction of each flange-shaped portion 158). Note that, as described above, when the circuit unit 10 is fixed to the housing 12, the screw 36 is inserted into each screw insertion hole 107 in the pressing component 16 and fastened to each screw fastening hole 38. In short, 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 are communicated 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 component 16.

Furthermore, the heat-generating component (precharge resistor 22) is held within the case 14 by placing both left and right end portions of each flange-shaped portion 158 on holding portions 76 that protrude into the inside of the case 14 (lower case 42). Thus, the left and right end portions of each flange-shaped portion 158 form a held portion 166. As a result, in embodiment 1, both the placement portions 164 and the held portions 166 are provided on each flange-shaped portion 158, and are therefore provided at the same position in the up-down direction.

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

<Assembly of the Circuit Unit 10>
The following describes a specific example of a method for assembling the circuit unit 10. Note that the method for assembling the circuit unit 10 is not limited to the embodiment described below.

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 overlapped with the terminal parts 116 of the relays 18a and 18b, respectively, and then secured with the bolts 120. At this time, the terminals 140 provided at the ends of the electric wires 134 and 136 are also overlapped with the terminal parts 116 of the positive relay 18a, and then fastened together with the bolts 120. Then, the relays 18a, 18b and the precharge relay 20 are placed on the lower case 42 and secured with bolts or screws.

The precharge resistor 22 is brought close to the holding portion 76 of the lower case 42 from above, and assembled while elastically deforming each of the flexible pieces 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, each flange-like portion 158 of the metal case 146 is placed on the protruding end faces 88 of each support portion 84 of the holding portion 76, and each held portion 166 at both left-right ends of each flange-like portion 158 is held by the holding portion 76.

Next, like the precharge resistor 22, the pressing part 16 is brought close to the holding part 76 from above, and assembled while elastically deforming each deflection piece 90 outward in the left-right direction. At this time, the pin-shaped parts 102 of each positioning boss 98 in the lower case 42 are inserted into each positioning hole 112 in the pressing part 16, so that the pressing part 16 is assembled in a state where it is positioned relative to the lower case 42. The lock claw parts 92 in each deflection piece 90 overcome the base plate part 104 in the pressing part 16, so that each deflection piece 90 elastically restores its original shape. As a result, the pressing surface 106, which is the lower surface of the pressing part 16, is superimposed on the upper surface (opposing surface 157) of the metal case 146. In particular, the pin-shaped parts 102 are inserted into each positioning hole 112, so that the pressing part 16 is prevented from tilting relative to the metal case 146, and the pressing surface 106 and the opposing surface 157 are superimposed with almost no gap. This places the metal case 146 on the holding portion 76, and the pressing part 16 on the metal case 146.

In this state, the inner left-right ends of each locking claw 92 overlap the left-right side edges of the base plate 104 in the up-down direction, and even when the precharge resistor 22 and the pressing part 16 are displaced upward, for example, the locking claws 92 and the base plate 104 engage with each other, preventing the precharge resistor 22 and the pressing part 16 from slipping out upward from the holding part 76. In other words, in this state, the precharge 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 provisionally assembled to the lower case 42.

Next, the upper case 40 is brought close from above to the lower case 42 to which the relays 18a, 18b, the precharge relay 20, the precharge resistor 22, and the pressing part 16 are assembled as described above, as shown in FIG. 8, and the upper case 40 and the lower case 42 are overlapped as shown in FIG. 9. As a result, the mounting parts 56 of the upper case 40 and the mounting parts 72 of the lower case 42 are overlapped, and the concave and convex shapes of the outer periphery parts of the upper case 40 and the lower case 42 are fitted together as described above. As a result, the horizontal positional deviation 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, in the circuit unit 10 before being assembled to the housing 12, for example, the bolts 30 may be inserted into the bolt insertion holes 54, 70 at the four corners of the periphery so that the upper case 40 and the lower case 42 are not separated from each other in the vertical direction.

<Assembly of the circuit unit 10 to the heat dissipation target (housing 12)>
A specific example of a method for assembling the circuit unit 10 to the housing 12, which is a 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.

First, the circuit unit 10 manufactured as described above is superimposed on a predetermined position on the upper surface 24 of the housing 12. For ease of understanding, the upper case 40 is shown separated from the lower case 42 in Figures 2 and 3, but 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 parts 130 of the heat dissipation bus bars 128a to 128d, and the elastic heat conductive member 68 is fixed to the lower wall part 152 of the precharge resistor 22 (metal case 146). The circuit unit 10 is superimposed on the upper surface 24 of the housing 12 so that the support protrusions 28 protruding from the upper surface 24 of the housing 12 fit into the recesses created by providing the mounting parts 72 on the lower surface of the circuit unit 10 (the lower surface 74 of the lower case 42). This positions the circuit unit 10 and the housing 12 in the horizontal direction, and vertically connects the bolt insertion holes 54, 70 at the four corners of the circuit unit 10 with the bolt fastening holes 32 in each support protrusion 28.

Then, by overlapping the circuit unit 10 on the upper surface 24 of the housing 12, the fixed parts 34a, 34b protruding upward from the upper 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 lower surface of the circuit unit 10 (the lower surface 74 of the lower case 42) and the upper surface 24 of the housing 12 are overlapped, the upper surface of each fixed part 34a protrudes upward beyond the protruding end surface 88 of each frame body part 78. As a result, when the lower surface 74 of the circuit unit 10 and the upper surface 24 of the housing 12 are overlapped, the upper surface of each fixed part 34a abuts against the flange-shaped parts 158 of each metal case 146 from below, and each of these flange-shaped parts 158 (particularly, each held part 166) is separated upward from the protruding end surface 88 of the holding part 76 (particularly the support part 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 communicate in the vertical direction. Also, each fixed portion 34b abuts against each outward protrusion 110 of the pressing part 16 from below, and the screw insertion holes 107 in each outward protrusion 110 communicate with the screw fastening holes 38 in each fixed portion 34b in the vertical direction.

In this state, the 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. Also, the screws 36 are inserted through the screw insertion holes 107 and the screw insertion grooves 160 through the insertion holes 58 in the upper case 40 and fastened to the screw fastening holes 38, fixing the fixing parts 108 formed around the screw insertion holes 107 and the fixed parts 34a, 34b. In particular, as described above, the fixing parts 108 and the fixed parts 34a are fixed together with the flange-shaped parts 158 (the mounting parts 164) sandwiched between them, that is, together with the mounting parts 164. This completes the assembly of the circuit unit 10 to the housing 12.

When the circuit unit 10 is assembled in the housing 12, the pressing surface 106 of the pressing part 16 is in contact with the opposing surface 157 of the precharge resistor 22 (metal case 146) over almost the entire surface. Then, by fixing each fixing part 108 and each fixed part 34a, 34b with the screw 36, the pressing part 16 is brought close to the housing 12, and the pressing part 16 presses the precharge resistor 22 against the elastic heat conductive member 68 and the housing 12 without going through the case 14 (lower case 42), that is, through the opening window 44. In addition, each heat dissipation part 130 of each heat dissipation bus bar 128a to 128d is in thermal contact with the housing 12 via each insulating sheet 64 and each elastic heat conductive member 66, and the thermal contact part 154 of the precharge 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 conductive 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.

As described above, the circuit unit 10 assembled inside the battery pack housing 12 has each of the connection parts 122a to 122d electrically connected to the battery and the inverter by conductive members (not shown). This electrically connects the battery and the inverter via the circuit unit 10.

Here, 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) at the time of starting the vehicle is relatively large, and if the inrush current flows through the main circuit, the main relay may be damaged. To prevent this damage, a precharge resistor is provided. That is, when the vehicle is started, the positive side relay 18a is turned OFF and the precharge relay 20 is turned ON, so that power is supplied from the battery to the capacitor in the inverter via the precharge circuit 132, and damage to the positive side relay 18a is avoided and the capacitor is charged. After the vehicle is started, the positive side relay 18a is turned ON and the precharge relay 20 is turned OFF, so that power is supplied from the battery to the inverter through the main circuit 126. Therefore, when the vehicle is started, the precharge circuit 132 is energized, causing the precharge resistor 22 to heat up, and after the vehicle is started, the main circuit 126 is energized, causing each relay 18a, 18b to heat up. In other words, the precharge resistor 22 and the positive relay 18a generate heat at different times.

In contrast, the housing 12 with which the thermal contact portion 154 is in thermal contact is also in thermal contact with the positive side relay 18a. This allows a common heat dissipation path to be configured for the precharge resistor 22 and the positive side 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 precharge resistor 22 and the positive side relay 18a.

In the circuit unit 10 of embodiment 1 having the above structure, a metal clad resistor capable of handling large currents is used as the precharge 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 if 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 precharge resistor can be reduced, and the circuit unit 10 can be made smaller.

In addition, the circuit unit 10 employs a pressing part 16 that presses the heat generating part (precharge resistor 22), and when the circuit unit 10 is fixed to the housing 12, the fixing parts 108 of the pressing part 16 are fixed to the fixing parts 34a, 34b of the housing 12, so that the thermal contact part 154 of the precharge resistor 22 is pressed approximately evenly against the housing 12 in the circumferential direction. This avoids the problem of the elastic heat conductive member 68 located between the thermal contact part 154 (lower wall part 152) and the housing 12 being partially suppressed in the circumferential direction, resulting in a deterioration in heat dissipation efficiency, and the pressing part 16 presses the precharge resistor 22 and the elastic heat conductive member 68 approximately evenly over the entire surface, thereby achieving good heat dissipation performance.

In particular, the pressing surface 106 of the pressing component 16 is in contact with the entire surface of 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 entire precharge resistor 22 can be pressed by the pressing component 16, that is, the entire elastic heat conductive member 68 can be pressed against the housing 12. As a result, improvement in the heat dissipation performance of the circuit unit 10 can be more reliably achieved.

The pressing part 16 is provided with fixing parts 108 at both ends in the longitudinal direction (front-rear direction), and is provided with ribs 114 extending in the longitudinal direction. As a result, even when the fixing parts 108 and the fixed parts 34a on both sides in the longitudinal direction are fixed by screws 36 as in embodiment 1, deformation of the pressing part 16 can be suppressed, and suppression of local compression of the elastic heat conductive member 68 can be avoided. As a result, further improvement in heat dissipation performance of the circuit unit 10 can be achieved. In particular, in embodiment 1, the fixing parts 108 are also provided at both ends in the short direction (left-right direction) of the pressing part 16, and the fixing parts 108 are provided at approximately equal intervals in the circumferential direction of the pressing part 16. As a result, the precharge resistor 22 and the elastic heat conductive member 68 can be pressed approximately evenly over the entire surface, and the heat dissipation performance can be further improved.

In addition, since the pressing part 16 is provided with the rib 114, it is necessary to distinguish between the front and back (upper and lower) of the pressing part 16. However, by providing each positioning hole 112 (and each positioning boss 98) at a position that is not symmetrical with respect to the line L1 or line L2 as in the first embodiment, it is possible to prevent erroneous assembly in the pressing part 16 when the pressing part 16 is in an inverted state. In particular, in the first embodiment, the pressing part 16 is rotationally symmetrical about a central axis extending in the vertical direction (a central axis extending in the vertical direction at the intersection of the line L1 and the line L2), and the pressing part 16 can be assembled to the lower case 42 without specifying one side/other in the front-rear direction or one side/other in the left-right direction. In addition, each positioning boss 98 and each positioning hole 112 are provided at a corresponding position, and when the pressing part 16 is assembled to the lower case 42, the pressing part 16 and the lower case 42 can be positioned relative to each other.

In the circuit unit 10, the precharge resistor 22, which is a heat-generating component, is held by a holding portion 76 provided on the case 14 before being attached to the housing 12, which is the heat dissipation target. However, when the circuit unit 10 is attached to the housing 12, the precharge resistor 22 is separated from the holding portion 76, and each mounting portion 164 of the precharge resistor 22 is fixed directly to each fixed portion 34a, 34b of the housing 12. This makes it unnecessary to consider the tolerance of the case 14, and allows for more reliable thermal contact between the thermal contact portion 154 of the precharge resistor 22 and the housing 12.

That is, for example, in the case of a conventional structure in which the precharge resistor is fixed to a case and the case is fixed to a housing to thermally contact the precharge resistor and the housing, it is necessary to take into account the tolerance of the case, and therefore the elastic heat conductive member needs to be made thicker. In other words, by directly fixing the precharge resistor 22 to the housing 12 as in embodiment 1, it is not necessary to take into account the tolerance of the case 14, and therefore the elastic heat conductive member 68 can be made thinner, thereby improving the heat conduction efficiency.

The holding portion 76 includes a frame portion 78 that surrounds the opening window 44 and protrudes inwardly of the case 14, and before the circuit unit 10 is fixed to the housing 12, the held portion 166 (flange-shaped portion 158) protruding from the peripheral wall portion 148 of the precharge resistor 22 to the outer periphery is placed on the protruding end surface 88 of the frame portion 78. This prevents the precharge resistor 22 from being pulled out through the opening window 44 in the circuit unit 10. 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, and when the precharge resistor 22 is held by the holding portion 76, the left-right displacement of the precharge resistor 22 is also suppressed. As a result, before the circuit unit 10 is fixed to the housing 12, the displacement of the precharge resistor 22 in the case 14 is suppressed, and damage to the precharge resistor 22 can be prevented.

Furthermore, the holding portion 76 includes a flexible piece portion 90 having a locking claw portion 92 at its protruding tip, and when the precharge resistor 22 and the pressing part 16 are assembled to the holding portion 76, each locking claw portion 92 abuts against the base plate portion 104 of the pressing part 16, thereby preventing the precharge resistor 22 and the pressing part 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.

The mounting parts 164 of the precharge resistor 22 are provided at the same positions as the held parts 166 in the vertical direction, and the fixed parts 34a, 34b of the housing 12 are arranged higher beyond the protruding end surface 88 of the frame body part 78 by fixing the circuit unit 10 to the housing 12. In the first embodiment, the mounting parts 164 and the held parts 166 of the precharge resistor 22 are both formed in the flange-shaped parts 158 of the metal case 146, and the precharge resistor 22 and the circuit unit 10 can be manufactured with a simpler structure than when, for example, the fixing part and the held part are provided separately. In addition, the fixed parts 34a, 34b protrude upward from the upper surface 24 of the housing 12, and a screw fastening hole 38 is provided at the upper end of each fixed part 34a, 34b. This allows the refrigerant flow path 26 to be formed in the housing 12 without considering the position of each screw fastening hole 38.

<Modification>
Although the first embodiment has been described above 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 modified examples of the embodiment are also included in the technical scope of the present disclosure.

(1) In the above embodiment, the heat dissipation target was the battery pack housing 12, but is not limited to this. In other words, the heat dissipation target may be any member that is in thermal contact with a heat-generating component when the circuit unit according to the present disclosure is mounted on 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.

(2) In the above embodiment, the heat generating component is constituted by a precharge resistor 22, but this is not limited to this embodiment. The heat generating component used 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.

(3) In the above embodiment, the opening window 44 and each of the insertion holes 46a on both sides in the front-rear direction were formed in the bottom wall portion 60 of the lower case 42 so as to be mutually connected, but the opening window and these insertion holes may be formed separately. In addition, the shape, size, number, etc. of the opening window and the insertion holes are not limited, and the shape, size, number, etc. of the opening window can be appropriately set according to the heat-generating component, and the shape, size, number, etc. of the insertion holes can be appropriately set according to the fixed portion provided on the heat dissipation target.

(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, but for example, two electric wires may extend from both sides in the longitudinal direction of the precharge resistor.

(5) In the above embodiment, the pressing part 16 had a rib 114 on its upper surface, but if the pressing part can press the heat-generating part approximately evenly, a rib may be provided on its lower surface. Note that such a rib is not essential. Also, in the above embodiment, the positioning holes 112 are provided in positions that are not symmetrical with respect to the straight lines L1 and L2, but this is not limited to the above. In other words, the pressing part may be designed to be able to be assembled to the lower case in an inverted state, which improves manufacturing efficiency.

10 Circuit unit 12 Housing (heat dissipation target)
14 Case 16 Pressing part 18 Relay 18a Positive electrode side relay 18b Negative electrode side relay 20 Precharge relay 22 Precharge resistor (heat generating part)
Reference Signs List 24 Upper surface 26 Coolant flow path 28 Support protrusion 30 Bolt 32 Bolt fastening hole 34 Fixed portion 34a (opposing in the front-rear direction) Fixed portion 34b (opposing in the left-right direction) Fixed portion 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 (opposing in the left-right direction) Upper bottom wall portion 50 Upper peripheral wall portion 52a to 52d Through window 54 Bolt insertion hole 56 Mounting portion 58 Insertion hole 60 Bottom wall portion 62 Opening window 64 Insulating sheets 66, 68 Elastic heat conductive member 70 Bolt insertion hole 72 Mounting portion 74 Lower surface 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 Flexure piece 92 Lock claw 94 Inclined surface 96 Gap 98 Positioning boss 100 Base 102 Pin-shaped portion 104 Base plate portion 106 Pressing surface 107 Screw insertion hole 108 Fixing portion 110 Outward protrusion 112 Positioning hole 114 Rib 116 Terminal portion 118 Current-carrying bus bars 118a to 118d First to fourth current-carrying bus bars 120 Bolts 122a to 122d Connection portion 124 Bolt 126 Main circuits 128a to 128d First to fourth heat dissipation bus bars 130 Heat dissipation portion 132 Pre-charge circuits 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 Hold portions L1, L2 Straight line

Claims (8)

A heat generating component;
a case for accommodating the heat generating component; and
a pressing part that presses the heat generating part,
the heat generating component has a thermal contact portion that is in thermal contact with a heat dissipation target via an elastic heat conductive member, and an opposing surface that faces the thermal contact portion;
the case has an opening window for exposing 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 part has a pressing surface that contacts the facing surface of the heat generating part and a fixing part that is fixed to the fixed part of the heat dissipation target,
A circuit unit, in which, with the fixing portion fixed to the fixed portion inserted into the insertion hole, the pressing surface of the pressing part contacts the opposing surface of the heat-generating component, and the pressing part fixed to the heat dissipation target presses the heat-generating component against the elastic heat-conducting member without going through the case. The circuit unit according to claim 1, wherein the pressing surface of the pressing component is in contact with the entire surface of the opposing surface of the heat generating component. The circuit unit according to claim 1 or claim 2, wherein the pressing surface of the pressing part is rectangular, the pressing part has the fixing parts provided on both ends of the pressing surface in the longitudinal direction, and the pressing part has a protruding rib extending in the longitudinal direction. the case has a holding portion that protrudes into the case and engages with the heat generating component to hold the heat generating component within the case,
the heat generating component has a mounting portion that is placed on the fixed portion and is fixed to the fixed portion together with the fixing portion,
3. The circuit unit according to claim 1, wherein the heat generating component is spaced apart from the holding portion by fixing the mounting portion of the heat generating component to the fixed portion. The circuit unit according to claim 4, wherein the holding portion includes a frame portion that surrounds the periphery of the opening window and protrudes inwardly of the case, and a held portion that protrudes from the peripheral wall of the heat generating component is placed on the protruding end surface of the frame portion. the retaining portion includes a flexible piece portion that protrudes inwardly of the case beyond the frame portion and is flexible and deformable toward an outer periphery of the opening window,
6. The circuit unit according to claim 5, wherein the flexible piece has a locking claw portion provided at a protruding tip and protruding toward the inner periphery of the opening window, and the flexible piece flexes and deforms toward the outer periphery to allow the heat-generating component and the pressing component to be assembled to the frame body, and when the held portion of the heat-generating component is placed on the protruding end face of the frame body, the locking claw portion of the flexible piece that has elastically returned overlaps the pressing component with a gap in between in the protruding direction of the frame body. The circuit unit according to claim 5, wherein when fixed to the heat dissipation target, the fixed portion of the heat dissipation target is arranged inwardly of the case beyond the protruding end face of the frame body in the protruding direction of the frame body. the case has positioning bosses disposed at a plurality of positions around the opening window and protruding beyond the fixing portion;
3. The circuit unit according to claim 1, wherein the pressing component has a plurality of positioning holes formed at positions corresponding to the positioning bosses and through which the positioning bosses are inserted.