Heat dissipation structure for heat generating component

Abstract

Disclosed is a heat dissipation structure for a heat generating component, wherein excellent heat dissipation performance can be demonstrated while suppressing an increase in size and a deterioration in mass productivity, even in the case of a large current.　A heat dissipation structure 10 for a heat generating component comprises: a heat generating component 14; and a layered bus bar 20 that has a first bus bar 16 and a second bus bar 18, said first bus bar 16 and said second bus bar 18 each including a connection section 24, 32 that is connected to the heat generating component 14, a heat dissipation section 28, 34 that is in thermal contact with a heat dissipation object 26, and a bent section 30, 36 that is provided between the connection section 24, 32 and the heat dissipation section 28, 34, wherein the first busbar 16 has a structure in which the connection section 24, the bent section 30, and the heat dissipation section 28 are integrated, the second busbar 18 has a separation section 38 separating the heat dissipation section 34 from the connection section 32, and has a structure that is separated into a connection section 32 side and a heat dissipation 34 side with the separation section 38 interposed therebetween, and the heat dissipation section 28 of the first busbar 16 and the heat dissipation section 34 of the second busbar 18 are in thermal contact with the heat dissipation object 26 in a condition of being overlapped with each other.

Description

Heat dissipation structure of heat-generating component

[0001] The present disclosure relates to a heat dissipation structure of a heat-generating component.

[0002] Conventionally, on the power supply path of a vehicle, there are mounted heat-generating components that generate heat by energization such as a relay that switches the electrical connection state between a battery and an in-vehicle load. In recent years, with the increase in the current of vehicles, the heat generated from the heat-generating components has also increased. Therefore, as described in Patent Document 1, a heat dissipation portion is provided on a bus bar connected to the terminal portion of the heat-generating component, and the heat dissipation portion of the bus bar is thermally contacted with a heat dissipation target disposed in the vicinity of a battery case or the like, so that the heat of the heat-generating component is dissipated to the heat dissipation target via the bus bar. A heat dissipation structure is adopted.

[0003] Japanese Patent Application Laid-Open No. 2018-93711

[0004] In the conventional heat dissipation structure of a heat-generating component, in order to thermally contact the heat dissipation portion of the bus bar connected to the terminal portion of the heat-generating component with the heat dissipation target, it is necessary to bend the bus bar in the middle of the extending direction so that the heat dissipation portion faces the heat dissipation target. Due to the further increase in the current of vehicles in recent electric vehicles, hybrid vehicles, etc., the cross-sectional area of the heat dissipation path required to achieve sufficient heat dissipation of the heat-generating component has also increased. If the bus bar is widened to increase the cross-sectional area, it will lead to an increase in the size of the bus bar and the product. Therefore, in order to ensure the required cross-sectional area, the plate thickness dimension of the bus bar has to be increased. As a result, it becomes difficult to bend the bus bar that constitutes the heat dissipation path of the heat-generating component itself, and there is a possibility that the mass productivity deteriorates.

[0005] Therefore, a heat dissipation structure of a heat-generating component that can exhibit good heat dissipation performance while suppressing an increase in size and deterioration of mass productivity even in the case of a large current is disclosed.

[0006] The heat dissipation structure for a heat-generating component of this disclosure comprises a heat-generating component that generates heat when an electric current is applied, and a first busbar and a second busbar that are stacked on top of each other in the thickness direction, wherein each of the first busbar and the second busbar is a laminated busbar that includes a connecting portion that connects to the terminal portion of the heat-generating component, a heat dissipation portion that is in thermal contact with the object to be heated, and a bent portion provided between the connecting portion and the heat dissipation portion, wherein the first busbar has a structure in which the connecting portion, the bent portion and the heat dissipation portion are connected and integrated in the longitudinal direction, and the second busbar has a separating portion that separates the heat dissipation portion from the connecting portion, and has a structure that is separated into the connecting portion side and the heat dissipation portion side via the separating portion, wherein the heat dissipation portion of the first busbar and the heat dissipation portion of the second busbar are in thermal contact with the object to be heated while stacked on top of each other in the thickness direction.

[0007] According to the heat dissipation structure of the heat-generating component disclosed herein, even with high currents, good heat dissipation performance can be achieved while suppressing increases in size and deterioration of mass production capabilities.

[0008] Figure 1 is a perspective view showing the heat dissipation structure of a heat-generating component according to Embodiment 1. Figure 2 is a plan view of the heat dissipation structure of the heat-generating component shown in Figure 1. Figure 3 is a longitudinal cross-sectional view showing an enlarged view of the main part of the III-III section in Figure 2. Figure 4 is an exploded perspective view of the heat dissipation structure of the heat-generating component shown in Figure 1. Figure 5 is a longitudinal cross-sectional view of the heat dissipation structure of the heat-generating component according to Embodiment 2, corresponding to Figure 3. Figure 6 is a longitudinal cross-sectional view of the heat dissipation structure of the heat-generating component according to Embodiment 3, corresponding to Figure 3. Figure 7 is a perspective view showing the heat dissipation structure of a heat-generating component according to Embodiment 4. Figure 8 is a longitudinal cross-sectional view showing an enlarged view of the main part of the VIII-VIII section in Figure 7.

[0009] <Description of Embodiments of the Disclosure> First, embodiments of the Disclosure will be listed and described. The heat dissipation structure of the heat-generating component of the Disclosure comprises: (1) a heat-generating component that generates heat when an electric current is applied, and a laminated busbar having a first busbar and a second busbar that are stacked on top of each other in the thickness direction, wherein each of the first busbar and the second busbar includes a connecting portion that connects to the terminal portion of the heat-generating component, a heat dissipation portion that is in thermal contact with the object to be heated, and a bent portion provided between the connecting portion and the heat dissipation portion, wherein the first busbar has a structure in which the connecting portion, the bent portion and the heat dissipation portion are connected in the longitudinal direction and integrated, and the second busbar has a separating portion that separates the heat dissipation portion from the connecting portion, and has a structure that is separated into the connecting portion side and the heat dissipation portion side via the separating portion, wherein the heat dissipation portion of the first busbar and the heat dissipation portion of the second busbar are in thermal contact with the object to be heated while stacked on top of each other in the thickness direction.

[0010] According to the heat dissipation structure for heat-generating components of this disclosure, the busbars that constitute the heat dissipation path from the heat-generating component to the heat-dissipating object, having a connecting portion that connects to the terminal portion of the heat-generating component and a heat dissipation portion that thermally contacts the heat-dissipating object, are composed of laminated busbars including a first busbar and a second busbar that are stacked on top of each other in the thickness direction. As a result, even when the required path cross-sectional area for the heat dissipation path increases due to high current, and the thickness dimension of the busbars must be increased, the adoption of laminated busbars allows for distribution between the first busbar and the second busbar while ensuring the required thickness dimension for the heat dissipation path. This makes it possible to keep the thickness dimensions of the first busbar and the second busbar smaller compared to when the heat dissipation path is composed of a single busbar, and it becomes easy to provide bent portions in each of the first busbar and the second busbar, thereby providing a heat dissipation structure for heat-generating components that suppresses increased size and deterioration of mass productionability.

[0011] Furthermore, the second busbar has a dividing section that separates the heat dissipation section from the connection section, and has a structure that separates the connection section side and the heat dissipation section side via the dividing section. This prevents the problem of difficulty in overlapping the heat dissipation sections of the first and second busbars, which are both connected to the terminal section of the heat-generating component, due to the bending tolerances of the bent sections of the respective first and second busbars. As a result, the heat dissipation sections of the first busbar and the second busbar can be thermally contacted with the heat-dissipating object while overlapping each other in the thickness direction, providing a heat dissipation structure for a heat-generating component that exhibits good heat dissipation performance.

[0012] The stacked busbars include configurations in which a second busbar is superimposed on a first busbar, and configurations in which a second busbar is superimposed on a first busbar. Furthermore, the stacked busbars may be used exclusively for heat dissipation, or they may also serve as a power supply path.

[0013] (2) In (1) above, it is preferable that the divided portion of the second busbar is provided between the bent portion and the heat dissipation portion, and that the heat dissipation portion has a flat plate shape that does not include the bent portion. Since the divided portion of the second busbar is provided between the bent portion and the heat dissipation portion, and the heat dissipation portion has a flat plate shape that does not include the bent portion, it becomes possible to overlap the heat dissipation portion of the second busbar with the heat dissipation portion of the first busbar over a wider area and make surface contact, thereby further improving the heat dissipation performance.

[0014] (3) In (1) or (2) above, it is preferable that one surface of the heat dissipation portion of the second busbar is superimposed on the other surface of the heat dissipation portion of the first busbar which is superimposed on the heat dissipation object and is in fixed contact with it, and the end of the second busbar on the connection side of the dividing portion is superimposed on the other surface of the heat dissipation portion of the first busbar, either directly or via the heat dissipation portion of the second busbar and is in fixed contact with it. Since the heat dissipation portion of the second busbar separated from the connection portion by the dividing portion is superimposed on the surface of the heat dissipation portion of the first busbar which is superimposed on the heat dissipation object and is fixed to it, it is possible to maintain a wide surface contact state between the opposing surfaces of the heat dissipation portions of the first busbar and the second busbar while securing the cross-sectional area of ​​the entire heat dissipation portion of the laminated busbar, and good heat dissipation performance can be ensured. Furthermore, since the end of the second busbar on the connection side of the divided section is similarly overlapped and fixed to the heat dissipation section of the second busbar, the heat from the heat-generating component that has been transferred to the connection section of the second busbar can be transferred from the end on the connection side to the heat dissipation section of the first busbar and the heat dissipation section of the second busbar, thereby improving heat dissipation performance. Note that "fixed contact" can be achieved by bolting or welding.

[0015] (4) In any one of (1) to (3) above, it is preferable that an expandable heat conductive member is interposed between the opposing surfaces of the heat dissipation portion of the first busbar or the second busbar and the heat dissipation object. By interposing an expandable heat conductive member such as a gap filler between the opposing surfaces of the heat dissipation portion of the first or second busbar and the heat dissipation object, deterioration of heat conductivity due to minute gaps between contact surfaces can be suppressed, and further improvement of heat dissipation performance can be achieved.

[0016] (5) In any one of (1) to (4) above, it is preferable that the laminated busbar has an electrical conductivity function, has a pair of connection parts at both ends in the longitudinal direction, has a heat dissipation part in the central part in the longitudinal direction, has a pair of bent parts on both sides of the heat dissipation part in the longitudinal direction, the heat dissipation part of the second busbar is separated from the pair of connection parts by a pair of dividing parts provided between the bent parts and the heat dissipation part on both sides of the heat dissipation part in the longitudinal direction, and the heat dissipation part has a flat plate shape that does not include the bent parts. When the laminated busbar is used as an electrical busbar having an electrical conductivity function, the flat plate shaped heat dissipation part that does not include the bent parts is separated from the pair of connection parts by a pair of separating parts provided on both sides of the heat dissipation part of the second busbar. As a result, even when the laminated busbar is used as a power-carrying busbar having a pair of connection parts on both sides in the longitudinal direction, wide surface contact between the heat dissipation part of the second busbar and the heat dissipation part of the first busbar can be achieved, and a heat dissipation path using the power-carrying busbar can be realized with excellent heat dissipation performance.

[0017] <Details of Embodiments of the Disclosure> Specific examples of the heat dissipation structure for the heat-generating component of the Disclosure will be described below with reference to the drawings. However, the Disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the Claims as indicated by the Claims.

[0018] <Embodiment 1> Hereinafter, the heat dissipation structure 10 for a heat-generating component according to Embodiment 1 of the present disclosure (hereinafter referred to as the heat dissipation structure 10) will be described with reference to Figures 1 to 4. This heat dissipation structure 10 is provided in, for example, electric vehicles and hybrid vehicles, and is used inside, for example, an electrical connection box 12 provided in a battery pack. With this heat dissipation structure 10, the heat generated by the heat-generating component (relay 14 in Embodiment 1) placed inside the electrical connection box 12 can be stably dissipated. In the vehicle, the electrical connection box 12 in which the heat dissipation structure 10 is provided can be positioned in any orientation, but in the following, "upper" will be described as the upper part in Figure 3, "lower" as the lower part in Figure 3, "left" as the left part in Figure 2, "right" as the right part in Figure 2, "front" as the lower part in Figure 2, and "rear" as the upper part in Figure 2. In addition, for multiple identical components, reference numerals may be assigned to only some of the components, and the reference numerals may be omitted for other components.

[0019] <Heat Dissipation Structure 10 for Heat-Generating Components> The heat dissipation structure 10 of Embodiment 1 includes a relay 14 as a heat-generating component that generates heat when energized, and a laminated busbar 20 including a first busbar 16 and a second busbar 18 that are stacked on top of each other in the thickness direction. The first busbar 16 includes a first connection portion 24 as a connection portion that connects to the terminal portion 22 of the relay 14, a first heat dissipation portion 28 as a heat dissipation portion that thermally contacts the heat to be dissipated (the housing 26 of the battery pack in Embodiment 1), and a first bent portion 30 as a bent portion provided between the first connection portion 24 and the first heat dissipation portion 28. Similarly, the second busbar 18 includes a second connection portion 32 as a connection portion that connects to the terminal portion 22 of the relay 14, a second heat dissipation portion 34 as a heat dissipation portion that thermally contacts the heat to be dissipated (the housing 26 of the battery pack), and a second bent portion 36 as a bent portion provided between the second connection portion 32 and the second heat dissipation portion 34.

[0020] The first busbar 16 has a structure in which the first connection portion 24, the first bent portion 30, and the first heat dissipation portion 28 are connected and integrated in the longitudinal direction. The second busbar 18 has a dividing portion 38 that separates the second heat dissipation portion 34 from the second connection portion 32, and has a structure in which it is separated into the second connection portion 32 side and the second heat dissipation portion 34 side via the dividing portion 38. The first heat dissipation portion 28 in the first busbar 16 and the second heat dissipation portion 34 in the second busbar 18 are in thermal contact with the housing 26 of the battery pack, which is the target of heat dissipation, in a state where they are overlapping each other in the thickness direction of the plates.

[0021] <Electrical Connection Box 12> The structure of the electrical connection box 12 is not limited, but the electrical connection box 12 of Embodiment 1 has a structure in which a circuit configuration 40, which includes relays 14, is housed in a case 42. Specifically, the circuit configuration 40 of Embodiment 1 includes a pair of relays 14, 14 that are separated from each other in the left-right direction, and one terminal portion 22 of each of these relays 14 is connected to the other by a stacked busbar 20 which includes a first busbar 16 and a second busbar 18. The connection between the terminal portion 22 of each of these relays 14 and the stacked busbar 20 is made by bolts 44. In addition, a busbar 48 having an external connection portion 46 is connected to the other terminal portion 22 of each relay 14 by bolts 44. That is, in Embodiment 1, the circuit configuration 40 is made up of each relay 14, the stacked busbar 20 and each busbar 48, and the stacked busbar 20 has a heat dissipation function as well as an electrical conduction function. Each relay 14 is a known type, and in Embodiment 1, a mechanical relay (contact relay) is used.

[0022] In Embodiment 1, the case 42 is composed of an upper case and a lower case 50 that can be assembled and separated in the vertical direction, but the upper case is omitted in the figure. The lower case 50 is a roughly rectangular box shape that opens upward as a whole, and has a roughly rectangular flat bottom wall portion 52 and a peripheral wall portion 54 that protrudes upward from the outer peripheral edge of the bottom wall portion 52. Each relay 14 is superimposed on the bottom wall portion 52 of the lower case 50 and fixed, for example, by a bolt-nut structure. The first heat dissipation portion 28 and the second heat dissipation portion 34 of the stacked busbar 20 connecting each relay 14, 14 are in thermal contact with the bottom wall portion 52 of the lower case 50 in a superimposed state. The electrical connection box 12 is fixed with the bottom wall portion 52 of the lower case 50 superimposed on the housing 26 of the battery pack which is the target of heat dissipation, and as a result the bottom wall portion 52 and the housing 26 are in thermal contact. Therefore, in Embodiment 1, in addition to the housing 26, the bottom wall portion 52 of the lower case 50 may also be included as a heat dissipation target for the heat generated by each relay 14.

[0023] In Embodiment 1, a first heat conduction member 56 is provided between the first heat dissipation section 28 and the bottom wall section 52 as a heat conduction member. A second heat conduction member 58 is provided between the bottom wall section 52 and the housing 26 as a heat conduction member. These first heat conduction member 56 and second heat conduction member 58 are made of, for example, a synthetic resin with excellent thermal conductivity, and known heat conduction sheets with elasticity can be used. In other words, in Embodiment 1, a first heat conduction member 56, which has elasticity, is provided between the opposing surfaces of the first heat dissipation section 28 and the bottom wall section 52 which is the target of heat dissipation. It is preferable that these first heat conduction member 56 and second heat conduction member 58 are compressed vertically by members that sandwich them vertically. This prevents gaps from forming between the first heat dissipation section 28 and the bottom wall section 52, and between the bottom wall section 52 and the housing 26.

[0024] <First Busbar 16> As described above, the first busbar 16 has a structure in which the first connection portion 24, the first bent portion 30, and the first heat dissipation portion 28 are connected and integrated in the longitudinal direction. Furthermore, since the first busbar 16 connects a pair of relays 14, 14, the first busbar 16 has a pair of first connection portions 24, 24 connected to each relay 14, and a pair of first bent portions 30 connected from each of these first connection portions 24. That is, the first busbar 16 is generally U-shaped, has a pair of first connection portions 24, 24 at both ends in the longitudinal direction, and has a first heat dissipation portion 28 in the central part in the longitudinal direction, and a pair of first bent portions 30, 30 are provided on both sides of this first heat dissipation portion 28 in the longitudinal direction. In Embodiment 1, the first busbar 16 is arranged to extend in the left-right direction, and at both ends in the left-right direction of the first heat dissipation section 28, which extends in the left-right direction, each first connection section 24 protrudes upward via each first bent section 30. Such a first busbar 16 is made of a metal with excellent conductivity, such as copper (including copper alloys) or aluminum (including aluminum alloys).

[0025] Each first connection portion 24 of the first busbar 16 has a bolt insertion hole 60 formed through it in the thickness direction (left-right direction), through which a bolt 44 for fixing to the terminal portion 22 of each relay 14 is inserted. Furthermore, as will be described later, the first heat dissipation portion 28 of the first busbar 16 is superimposed on the second heat dissipation portion 34 of the second busbar 18 and fixed by a pair of bolts 76, 76. As a result, bolt insertion holes 62 through which each bolt 76 is inserted are formed at both ends of the first heat dissipation portion 28 in the longitudinal direction (left-right direction), through which the bolts 76 are inserted. For example, the inner circumferential surface of the bolt insertion hole 62 may have a female thread that engages with the male thread of each bolt 76.

[0026] <Second Busbar 18> The second busbar 18 is generally U-shaped and extends in the left-right direction, similar to the first busbar 16, but as described above, it is provided with a dividing portion 38 to separate it into the second connection portion 32 side and the second heat dissipation portion 34 side. In Embodiment 1, the dividing portion 38 of the second busbar 18 is provided between the second bend portion 36 and the second heat dissipation portion 34. In particular, in Embodiment 1, a pair of dividing portions 38, 38 are provided separated from each other in the left-right direction, and each dividing portion 38 is provided on both sides of the second heat dissipation portion 34. These dividing portions 38 separate the second heat dissipation portion 34 from each second connection portion 32. In short, the second busbar 18 is composed of a pair of L-shaped portions 64, 64 provided at both the left and right ends and facing the second connection portion 32, and a flat plate-shaped second heat dissipation portion 34 provided in the center in the left-right direction and facing the second heat dissipation portion 34. Each L-shaped portion 64 and the second heat dissipation portion 34 constituting the second busbar 18 is made of the same material as the first busbar 16. The thickness dimensions of the first busbar 16 and the second busbar 18 are not limited, but both have a certain thickness, and in Embodiment 1, the second busbar 18 is thicker than the first busbar 16. Furthermore, the first busbar 16 does not need to have a constant thickness along its entire length in the left-right direction, and its thickness may differ in parts. Similarly, the thickness dimensions of each L-shaped portion 64 and the second heat dissipation portion 34 constituting the second busbar 18 may differ from each other, but in Embodiment 1, each L-shaped portion 64 and the second heat dissipation portion 34 are formed with approximately the same thickness.

[0027] Each L-shaped portion 64, 64 is the same shape as the others and is separated from each other in the left-right direction. Each L-shaped portion 64 includes a second connecting portion 32 that is superimposed on the terminal portion 22 of each relay 14 via each first connecting portion 24, each second bent portion 36 connected to each second connecting portion 32, and each flat portion 66 that extends flatly inward in the left-right direction from each second bent portion 36. In other words, a pair of flat portions 66, 66 are separated from each other by a predetermined distance in the left-right direction, and each second connecting portion 32 protrudes upward from both ends of each flat portion 66 in the left-right direction via each second bent portion 36. Each second connecting portion 32 has a bolt insertion hole 68 through which a bolt 44 for fixing to the terminal portion 22 of each relay 14 is inserted, and the bolt insertion hole 68 is formed in the thickness direction (left-right direction) of each second connecting portion 32. Furthermore, each flat portion 66 has a bolt insertion hole 70 through which the bolts 76 described later are inserted, extending in the thickness direction (vertical direction) of each flat portion 66.

[0028] The second heat dissipation section 34 of Embodiment 1 is a rectangular flat plate shape extending in the left-right direction and does not include the second bent section 36. The second heat dissipation section 34 is formed with a length dimension (left-right dimension) that spans each flat section 66 of each L-shaped section 64 which are separated from each other in the left-right direction. That is, when the first bus bar 16 and the second bus bar 18 are stacked and fixed together, the left-right ends of the second heat dissipation section 34 are sandwiched between each flat section 66 of each L-shaped section 64 and the first heat dissipation section 28 of the first bus bar 16, and the left-right ends of the second heat dissipation section 34 constitute an intermediate laminated section 72. Bolt insertion holes 74 through which bolts 76, which will be described later, are inserted are formed in each intermediate laminated section 72, penetrating in the thickness direction (vertical direction) of each intermediate laminated section 72.

[0029] <Laminated Busbar 20> The laminated busbar 20 is constructed by overlapping and fixing the first busbar 16 and the second busbar 18. Specifically, the laminated busbar 20 has a pair of first connecting parts 24 and a pair of second connecting parts 32 provided at both ends in the longitudinal direction (left-right direction). The laminated busbar 20 also has a first heat dissipation part 28 and a second heat dissipation part 34 in the central part in the longitudinal direction. Furthermore, the laminated busbar 20 has a pair of first bent parts 30 and a pair of second bent parts 36 provided on both sides of each heat dissipation part 28 and 34 in the longitudinal direction. In Embodiment 1, the second busbar 18 is superimposed on the first busbar 16, and specifically, the second heat dissipation part 34 and the flat parts 66 of each L-shaped part 64 are superimposed on the first heat dissipation part 28 of the first busbar 16. As a result, the laminated busbar 20 has a partially three-layer structure. The bolt insertion holes 62, 74, and 70 in each intermediate laminated section 72 and each flat section 66 of the first heat dissipation section 28 and the second heat dissipation section 34 are in communication with each other in the vertical direction, and the first heat dissipation section 28, the second heat dissipation section 34 and each L-shaped section 64 are fixed to each other by bolts 76 inserted through each bolt insertion hole 62, 74, and 70.

[0030] Here, the first heat dissipation section 28, the second heat dissipation section 34, and the flat sections 66 of each L-shaped section 64 are all flat in shape, and substantially the entire lower surface of the second heat dissipation section 34 is superimposed on the upper surface of the first heat dissipation section 28 in a state of surface contact. Similarly, substantially the entire lower surface of each flat section 66 is superimposed on the upper surface of the second heat dissipation section 34 in a state of surface contact. That is, one surface (lower surface) of the first heat dissipation section 28 is superimposed on the bottom wall 52 of the lower case 50, which is the target of heat dissipation, via the first heat conductive member 56, and the second heat dissipation section 34 is superimposed on the other surface (upper surface) of the first heat dissipation section 28 and is in fixed contact. Furthermore, the ends of the second busbar 18 on the second connection section 32 side (each flat section 66) are superimposed on the other surface (upper surface) of the first heat dissipation section 28 via the second heat dissipation section 34 and are in fixed contact.

[0031] Furthermore, each first connection portion 24 on the first busbar 16 and each second connection portion 32 on the second busbar 18 (each L-shaped portion 64) are superimposed in the left-right direction, which is the thickness direction, and the bolt insertion holes 60 on each first connection portion 24 and the bolt insertion holes 68 on each second connection portion 32 are in mutual communication in the left-right direction. Each of these first connection portions 24 and each second connection portion 32 is superimposed on the terminal portion 22 of each relay 14, and bolts 44 inserted through the bolt insertion holes 60, 68 are fastened to each terminal portion 22. In this way, the laminated busbar 20 consisting of the first busbar 16 and the second busbar 18 is electrically and thermally connected to each relay 14, which is a heat-generating component. Each of the first connection portions 24 and each second connection portion 32 has a flat shape, and substantially the entire outer surface of each second connection portion 32 in the left-right direction is superimposed on the inner surface of each first connection portion 24 in the left-right direction in a state of surface contact.

[0032] The electrical junction box 12, with the structure described above, is fixed to the battery pack housing 26, which is the target of heat dissipation, by overlapping the lower surface of the bottom wall portion 52 of the lower case 50 via the second heat conductive member 58, as previously mentioned. In addition, terminals provided on the ends of external electric wires (not shown) are connected to the external connection portion 46 of each busbar 48 connected to the other terminal portion 22 of each relay 14, thereby supplying power to the circuit configuration 40 inside the electrical junction box 12. When power is supplied to each relay 14, each relay 14 generates heat. The heat generated by each relay 14 is dissipated from the battery pack housing 26 via the first heat dissipation portion 28 and the second heat dissipation portion 34, the first heat conductive member 56, the bottom wall portion 52 of the lower case 50, and the second heat conductive member 58, which are overlapped with each other.

[0033] Here, according to the heat dissipation structure 10 for the heat-generating component of Embodiment 1, it is possible to avoid increasing the size of the electrical connection box 12 while achieving good mass productivity and heat dissipation performance. That is, when considering heat dissipation associated with the increased current of vehicles, simply making the busbars wider or increasing their thickness would inevitably lead to increased size and deterioration of mass productivity. However, the busbars connected to the heat-generating component (relay 14) are made into a laminated busbar 20 consisting of a first busbar 16 and a second busbar 18. This makes it possible to handle heat dissipation when a large current flows without making the busbars connected to the relay 14 particularly wider, and while ensuring the overall thickness of the laminated busbar 20. Furthermore, when providing a bend in the busbars connected to the relay 14, the bends (each first bend 30 and each second bend 36) can be provided on the first busbar 16 and second busbar 18, which have relatively small thickness dimensions, thereby improving the mass productivity of the laminated busbar 20 and, consequently, the electrical connection box 12.

[0034] In particular, in Embodiment 1, the second busbar 18 is separated into L-shaped portions 64 and second heat dissipation portions 34 at each dividing portion 38, thereby improving heat dissipation performance. That is, for example, if the first busbar and the second busbar are simply bent into a U-shape, bending tolerances make it difficult to overlap the first busbar and the second busbar without gaps, and there is a risk that a gap will be created between the first heat dissipation portion and the second heat dissipation portion, worsening the heat dissipation performance. In contrast, in Embodiment 1, the second heat dissipation portion 34 is formed separately from each L-shaped portion 64, and the second heat dissipation portion 34 is sandwiched between the flat portion 66 of each L-shaped portion 64 and the first heat dissipation portion 28 and fixed with bolts 76. As a result, the first heat dissipation section 28 and the second heat dissipation section 34, which are each shaped like flat plates, can be superimposed with virtually no gaps. Furthermore, even if each flat section 66 lifts up from the second heat dissipation section 34 due to bending tolerances, the axial force (tightening force) of each bolt 76 allows each flat section 66 and the second heat dissipation section 34 to be superimposed with virtually no gaps. Consequently, no gaps occur at the overlapping portion of the first busbar 16 and the second busbar 18, and the heat generated in each relay 14 can be effectively dissipated through the first heat dissipation section 28 and the second heat dissipation section 34.

[0035] Each divided portion 38 of the second busbar 18 is provided between the second bent portion 36 and the second heat dissipation portion 34, and the second heat dissipation portion 34 has a flat plate shape that does not include the second bent portion 36. As a result, the lower surface of the second heat dissipation portion 34 can be in surface contact with the upper surface of the first heat dissipation portion 28 over almost its entire surface, and excellent heat dissipation performance can be achieved in heat dissipation through the first heat dissipation portion 28 and the second heat dissipation portion 34.

[0036] The second heat dissipation section 34 is superimposed on and fixedly in contact with the other surface (upper surface) of the first heat dissipation section 28, and one surface (lower surface) of the first heat dissipation section 28 is superimposed on and fixedly in contact with the bottom wall 52 of the lower case 50, which is the object of heat dissipation, via the first heat conductive member 56. In addition, the ends (each flat portion 66) of the second busbar 18 on the side of each second connection portion 32 rather than each division portion 38 are superimposed on and fixedly in contact with the other surface (upper surface) of the first heat dissipation section 28 via the second heat dissipation section 34. As a result, the heat generated in each relay 14 is not only transferred to the first heat dissipation section 28 through each first connection section 24 and each first bent section 30, but also transferred to the second heat dissipation section 34 through each second connection section 32, each second bent section 36 and each flat section 66, thus enabling more efficient heat dissipation through the first heat dissipation section 28 and the second heat dissipation section 34.

[0037] A heat-conducting member (first heat-conducting member 56) with elasticity is provided between the opposing surfaces of the first heat-dissipating section 28 and the bottom wall 52 of the lower case 50, which is the target of heat dissipation. This prevents gaps from forming between the first heat-dissipating section 28 and the bottom wall 52, thereby enabling good heat dissipation performance.

[0038] In particular, in Embodiment 1, the laminated busbar 20 has not only a heat dissipation function but also a current-carrying function, and the laminated busbar 20 is roughly U-shaped, with each connection part (each first and second connection part 24, 32) protruding upward from both ends of the heat dissipation part (first and second heat dissipation parts 28, 34) in the longitudinal central part via each bent part (each first and second bent part 30, 36). As a result, it is not necessary to provide a separate busbar for current transport, and it is possible to carry a large current through the laminated busbar 20 which has a relatively large cross-sectional area.

[0039] <Embodiment 2> Hereinafter, the heat dissipation structure 80 of the heat-generating component according to Embodiment 2 of the present disclosure (hereinafter, heat dissipation structure 80) will be described with reference to Figure 5. The basic structure of the heat dissipation structure 80 in Embodiment 2 is the same as that of Embodiment 1, but Embodiment 2 differs from Embodiment 1 in that the left and right ends of the second heat dissipation section 82 are not sandwiched between the flat sections 66 of each L-shaped section 64 and the first heat dissipation section 28 of the first busbar 16. Hereinafter, the differences from Embodiment 1 will be mainly described, and detailed explanations will be omitted for members and parts that are substantially the same as those in Embodiment 1, by denoting them with the same reference numerals in the figures as in Embodiment 1.

[0040] In Embodiment 2, the first busbar 16 has the same shape as in Embodiment 1, but in the first heat dissipation section 28, bolt insertion holes 62 are formed not only at both ends in the longitudinal direction (left and right direction) but also in the longitudinal center.

[0041] <Second Busbar 84> In Embodiment 2, the second busbar 84 is also provided with a pair of separating portions 38, 38 that separate the second heat dissipation portion 82 from each second connection portion 32, and the second busbar 84 is configured to include a pair of L-shaped portions 64, 64 provided at both ends in the left-right direction and a flat plate-shaped second heat dissipation portion 82 provided in the center in the left-right direction. In Embodiment 1, the second heat dissipation portion 34 was formed with a left-right dimension that spanned the flat portion 66 of each L-shaped portion 64, but in Embodiment 2, the second heat dissipation portion 82 has a left-right dimension that is smaller than the distance between the opposing surfaces of the flat portions 66, 66 of each L-shaped portion 64. As a result, the second heat dissipation section 82 is located between flat sections 66, 66 that are separated from each other in the left-right direction, and the inward end faces of each flat section 66 in the left-right direction and the outward end faces of the second heat dissipation section 82 in the left-right direction are separated by a predetermined gap and face each other in the left-right direction. The gaps between each flat section and the second heat dissipation section 82 in the left-right direction constitute each of the above-mentioned dividing sections 38. In the second embodiment, in addition to the flat sections 66 of each L-shaped section 64, bolt insertion holes 70 through which each bolt 76 is inserted are also formed in the left-right central portion of the second heat dissipation section 82.

[0042] That is, in Embodiment 2, the second heat radiating portion 82 is not provided between the flat portion 66 of each L-shaped portion 64 and the first heat radiating portion 28, and the end portion (each flat portion 66) on the second connection portion 32 side rather than each dividing portion 38 of the second bus bar 84 is directly overlapped and fixedly contacted with the other surface (upper surface) of the first heat radiating portion 28 by each bolt 76. Further, the second heat radiating portion 82 is also directly overlapped with the upper surface of the first heat radiating portion 28 at the central portion in the left-right direction of the first heat radiating portion 28 and is fixed by bolts 76. Thereby, the lower surface of the second heat radiating portion 82 is overlapped with the upper surface of the first heat radiating portion 28 substantially without a gap over substantially the entire surface.

[0043] Also in the heat radiating structure 80 of Embodiment 2 having such a structure, since the laminated bus bar 86 is configured to include the first bus bar 16 and the second bus bar 84 having relatively small thickness dimensions, excellent mass productivity is exhibited even if it has bent portions (each first bent portion 30 and each second bent portion 36). In particular, since each L-shaped portion 64 and the second heat radiating portion 82 are divided by each dividing portion 38, the bending tolerance in each second bent portion 36 does not affect the second heat radiating portion 82, and a gap is stably prevented from occurring between the second heat radiating portion 82 and the first heat radiating portion 28. As a result, deterioration of the heat radiating performance through the first heat radiating portion 28 and the second heat radiating portion 82 can be avoided. Further, the laminated bus bar 86 of Embodiment 2 does not have a three-layer structure like the laminated bus bar 20 of Embodiment 1, and the thickness dimension of the laminated bus bar 86 at the fastening portion of each bolt 76 can be made smaller than that of Embodiment 1.

[0044] <Embodiment 3> Hereinafter, a heat radiating structure 90 (hereinafter, the heat radiating structure 90) of a heat generating component according to Embodiment 3 of the present disclosure will be described with reference to FIG. 6. The basic structure of the heat radiating structure 90 in Embodiment 3 is the same as that in Embodiment 1, but in Embodiment 3, the first bus bar 94 is located above the second bus bar 92, which is different from Embodiment 1. Hereinafter, mainly the differences from Embodiment 1 will be described, and members and parts substantially the same as those in Embodiment 1 will be denoted by the same reference numerals as those in Embodiment 1 in the drawings, and detailed description thereof will be omitted.

[0045] Note that the first bus bar 94 in Embodiment 3 has the same shape as that in the first embodiment, and is formed in a substantially U shape in which the first connection portions 24 protrude upward through the first bending portions 30 at both longitudinal ends (left and right directions) of the first heat radiation portion 28.

[0046] <Second bus bar 92> The second bus bar 92 in Embodiment 3 also has a dividing portion 38 that separates each L-shaped portion 64 on the side of the second connection portion 32 and the second heat radiation portion 34, similar to Embodiment 1. In Embodiment 1, the second heat radiation portion 34 was overlapped with the lower surface of the flat portion 66 in each L-shaped portion 64. However, in Embodiment 3, the second heat radiation portion 34 is overlapped with the upper surface of each flat portion 66, and further, the first heat radiation portion 28 is overlapped with the upper surface of the second heat radiation portion 34. That is, also in Embodiment 3, the second heat radiation portion 34 is formed with a left-right dimension that spans the flat portions 66, 66 on both left and right sides, and intermediate laminated portions 72 are respectively formed by both left and right ends of the second heat radiation portion 34 in the left-right direction.

[0047] Therefore, in Embodiment 3, at the fastening portion of each bolt 76, the first heat radiation portion 28, the second heat radiation portion 34, and each flat portion 66 are overlapped in this order from above to form a three-layer structure, and the overlapping surfaces thereof are in contact with substantially no gap. Thereby, the first bus bar 94 and the second bus bar 92 are electrically and thermally connected. And the flat portion 66 of each L-shaped portion 64 in the second bus bar 92 is in thermal contact with the bottom wall portion 52 of the lower case 50, which is the heat radiation target, via the first heat conduction member 56. In other words, the flat portions 66 and the first heat conduction member 56 are provided between the opposing surfaces of the second heat radiation portion 34 and the bottom wall portion 52, which is the heat radiation target.

[0048] Also in the heat radiation structure 90 of Embodiment 3 having the above-described structure, since the first heat radiation portion 28 and the second heat radiation portion 34 are in an overlapped state and are in thermal contact with the heat radiation target (bottom wall portion 52) through each flat portion 66, the same effects as those in Embodiment 1 can be exhibited. In particular, since each dividing portion 38 is provided in the second bus bar 92, even when the second bending portion 36 is provided, the first heat radiation portion 28 and the second heat radiation portion 34 can be brought into contact with substantially no gap, and a decrease in heat radiation performance can be avoided.

[0049] <Embodiment 4> Hereinafter, the heat dissipation structure 100 for a heat-generating component according to Embodiment 4 of the present disclosure (hereinafter, heat dissipation structure 100) will be described with reference to Figures 7 and 8. In Embodiment 1, a stacked busbar 20 was used as a busbar connecting a pair of relays 14, 14. In Embodiment 4, however, one relay 14 is provided inside the electrical connection box 102, and one end (left end) of the stacked busbar 104 is connected to the terminal portion 22 of the relay 14, while the other end (right end) of the stacked busbar 104 is configured as an external connection portion 46. This stacked busbar 104 is configured to include a first busbar 106 and a second busbar 108, similar to Embodiment 1.

[0050] <First Busbar 106> The first busbar 106 in Embodiment 4 has the same overall shape as the first busbar 16 in Embodiment 1, and is substantially U-shaped. That is, the first busbar 106 is equipped with a first heat dissipation section 28 that extends in the left-right direction, and portions that protrude upward from both left and right ends of this first heat dissipation section 28 extend via each first bent portion 30. At the left end of the first busbar 106, the portion that protrudes upward from the first bent portion 30 is the first connection portion 24 that is connected to the terminal portion 22 of the relay 14. At the right end of the first busbar 106, an external connection portion 46 is formed by a portion that protrudes upward from the first bent portion 30 and protrudes outward (to the right) in the left-right direction from its upper end.

[0051] <Second Busbar 108> The second busbar 108 in Embodiment 2 is a substantially L-shaped member that extends in the left-right direction as a whole, with a dividing portion 38 provided in the middle portion in the longitudinal direction (left-right direction), and is composed of an L-shaped portion 64 which is the member on the second connection portion 32 side and a second heat dissipation portion 34. Similar to Embodiment 1, the second heat dissipation portion 34 is substantially flat in shape, and the L-shaped portion 64 is superimposed from above on one end (left end) of the second heat dissipation portion 34, thereby forming a second busbar 108 that is substantially L-shaped as a whole.

[0052] <Laminated Busbar 104> The laminated busbar 104 is formed by overlapping the first busbar 106 and the second busbar 108 and fixing them to each other. Specifically, the second heat dissipation section 34 is superimposed on the first heat dissipation section 28 of the first busbar 106 from above, and the L-shaped section 64 is further superimposed on the left end of the second heat dissipation section 34 from above. As a result, the left end of the second heat dissipation section 34 is sandwiched between the first heat dissipation section 28 and the flat section 66 of the L-shaped section 64, forming an intermediate laminated section 72, and the three layers of the first heat dissipation section 28, the second heat dissipation section 34 and the flat section 66 are fixed together by bolts 76. On the other hand, the right end of the second heat dissipation section 34 is only superimposed on the first heat dissipation section 28, and the two layers of the first heat dissipation section 28 and the second heat dissipation section 34 are fixed together by bolts 76.

[0053] In the heat dissipation structure 100 of Embodiment 4, which has the structure described above, the laminated busbar 104 is composed of a first busbar 106 and a second busbar 108 with relatively small thickness dimensions, so the same effects as in Embodiment 1 can be achieved. Furthermore, even if a second bent portion 36 is provided on the second busbar 108, the first heat dissipation portion 28 and the second heat dissipation portion 34 can be overlapped with virtually no gap, thereby avoiding a decrease in heat dissipation performance.

[0054] <Modifications> Although Embodiments 1 to 4 have been described in detail above as specific examples of the present disclosure, the present disclosure is not limited by these specific descriptions. Modifications, improvements, etc., to the extent that they can achieve the objectives of the present disclosure are included in the present disclosure. For example, the following modifications of embodiments are also included in the technical scope of the present disclosure.

[0055] (1) In Embodiment 1, the first busbar 16 and the second busbar 18 were fixed by bolts 76. However, the method of fixing the first busbar and the second busbar is not limited to bolt fixing. They may be fixed by welding, such as laser welding, or by other known fixing methods. The same applies to Embodiments 2 to 4.

[0056] (2) In Embodiment 1, the thickness of the second busbar 18 was greater than the thickness of the first busbar 16. However, the embodiment is not limited to this, and the thickness of the first busbar and the second busbar may be equal to each other, or the thickness of the second busbar may be smaller than the thickness of the first busbar. Note that the first busbar has first bends at two locations within its member, while the second busbar has a second bend at one location in each L-shaped section. Therefore, the first busbar is bent more times within a single member, and when comparing the thickness of the second busbar and the thickness of the first busbar, it is preferable that the thickness of the first busbar be smaller. In addition, the thickness of both the first busbar and the second busbar may differ in the longitudinal direction according to their heat dissipation characteristics. For example, the thickness of each L-shaped section and the second heat dissipation section constituting the second busbar may differ. The same applies to Embodiments 2 to 4.

[0057] (3) In Embodiment 1, the laminated busbar 20 (first busbar 16 and second busbar 18) had both a heat dissipation function and a power supply function, but the laminated busbar may have only a heat dissipation function, and the power supply function may be performed by a separately provided power supply busbar. The same applies to Embodiments 2 to 4.

[0058] (4) The first heat dissipation part in the first busbar and the second heat dissipation part in the second busbar only need to be in thermal contact, and a heat-conductive member with elasticity may be provided between the first heat dissipation part and the second heat dissipation part. This can more reliably prevent a gap from forming between the first heat dissipation part and the second heat dissipation part. This heat-conductive member may also have electrical insulating properties, and the first busbar having the first heat dissipation part and the second busbar having the second heat dissipation part do not need to be electrically connected.

[0059] (5) The first busbar and the second busbar are not limited to a two- or three-layer laminated structure. For example, the second heat dissipation section 34 in Embodiment 1 may be made into a two- or more-layer laminated structure, resulting in an overall laminated structure of four or more layers. Furthermore, in Embodiments 3 and 4, the configuration of Embodiment 2 may be combined and adopted. That is, in Embodiments 3 and 4, the second heat dissipation section may be superimposed on the first heat dissipation section rather than on the flat section of the L-shaped section.

[0060] (6) In the above embodiment, a relay 14 was described as a heat-generating component, but this is merely an example, and other known heat-generating components such as fuses or resistors may be used. Furthermore, even if the heat-generating component is a relay, it is not limited to a mechanical relay (contact relay) as in the above embodiment, but may also be a semiconductor relay (contactless relay).

[0061] 10 Heat dissipation structure (Embodiment 1) (for heat-generating components) 12 Electrical junction box 14 Relay (heat-generating component) 16 First busbar 18 Second busbar 20 Laminated busbar 22 Terminal section 24 First connection section (connection section) 26 Housing (of battery pack) (target of heat dissipation) 28 First heat dissipation section (heat dissipation section) 30 First bend section (bend section) 32 Second connection section (connection section) 34 Second heat dissipation section (heat dissipation section) 36 Second bend section (bend section) 38 Separation section 40 Circuit configuration 42 Case 44 Bolt 46 External connection section 48 Busbar 50 Lower case 52 Bottom wall section (target of heat dissipation) 54 Peripheral wall section 56 First heat conduction member (heat conduction member) 58 Second heat conduction member (heat conduction member) 60, 62 Bolt insertion holes 64 L-shaped section 66 Flat sections 68, 70 Bolt insertion holes 72 Intermediate laminated section 74 Bolt insertion holes 76 Bolt 80 Heat dissipation structure (Embodiment 2) (for heat-generating components) 82 Second heat dissipation section 84 Second bus bar 86 Laminated bus bar 90 Heat dissipation structure (Embodiment 3) (for heat-generating components) 92 Second bus bar 94 First bus bar 100 Heat dissipation structure (Embodiment 4) (for heat-generating components) 102 Electrical connection box 104 Laminated bus bar 106 First bus bar 108 Second bus bar

Claims

1. A heat dissipation structure for a heat-generating component, comprising a heat-generating component that generates heat when energized, and a laminated busbar having a first busbar and a second busbar that are stacked on top of each other in the thickness direction, wherein each of the first busbar and the second busbar includes a connecting portion that connects to the terminal portion of the heat-generating component, a heat dissipation portion that thermally contacts the object to be heated, and a bent portion provided between the connecting portion and the heat dissipation portion, wherein the first busbar has a structure in which the connecting portion, the bent portion and the heat dissipation portion are connected and integrated in the longitudinal direction, and the second busbar has a separating portion that separates the heat dissipation portion from the connecting portion, and has a structure that is separated into the connecting portion side and the heat dissipation portion side via the separating portion, wherein the heat dissipation portion of the first busbar and the heat dissipation portion of the second busbar are stacked on top of each other in the thickness direction and are thermally in contact with the object to be heated.

2. The heat dissipation structure for a heat-generating component according to claim 1, wherein the divided portion of the second busbar is provided between the bent portion and the heat dissipation portion, and the heat dissipation portion has a flat plate shape that does not include the bent portion.

3. The heat dissipation structure for a heat-generating component according to claim 1 or 2, wherein one surface of the heat dissipation portion of the second busbar is superimposed on the other surface of the heat dissipation portion of the first busbar which is superimposed on the heat dissipation object, and the end of the second busbar on the connection side of the dividing portion is superimposed on the other surface of the heat dissipation portion of the first busbar, either directly or via the heat dissipation portion of the second busbar, and in fixed contact.

4. A heat dissipation structure for a heat-generating component according to claim 1 or 2, wherein an expandable and contractible heat conductive member is interposed between the opposing surfaces of the heat dissipation portion of the first busbar or the second busbar and the heat dissipation target.

5. The heat dissipation structure for a heat-generating component according to claim 1 or 2, wherein the laminated busbar has an electrical conductivity function, has a pair of connection portions at both ends in the longitudinal direction, has a heat dissipation portion in the central part in the longitudinal direction, has a pair of bent portions on both sides of the heat dissipation portion in the longitudinal direction, the heat dissipation portion of the second busbar is separated from the pair of connection portions by a pair of dividing portions provided between the bent portions and the heat dissipation portion on both sides of the heat dissipation portion in the longitudinal direction, and the heat dissipation portion has a flat plate shape that does not include the bent portions.

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