Electrical junction box

Abstract

An electrical junction box (11) is provided with: a resin base member (12) having a through-hole (12a) penetrating downward (Z2); a first bus bar (13) disposed above (Z1) the base member (12) at a position corresponding to the through-hole (12a); a second bus bar (14) disposed above (Z1) the first bus bar (13) in an overlapping manner; and a bolt (15) and a nut (16) for fastening the first bus bar (13) and the second bus bar (14) at a position corresponding to the through-hole (12a). A bottom face (13b) of the first bus bar (13) disposed above (Z1) a heat dissipation member (21) and exposed from the through-hole (12a) is connected to the heat dissipation member (21) via a heat-dissipating gap filler (22). The first bus bar (13) has a housing section (15c) that houses a head (15a) of the bolt (15).

Description

Electrical junction box

[0001] The present disclosure relates to an electrical junction box.

[0002] Conventionally, electrical junction boxes include a resin base member, a first bus bar, a second bus bar, bolts, and nuts. The base member has through holes extending downward. The first bus bar is disposed above the base member at a position corresponding to the through holes. The second bus bar is disposed above the first bus bar and overlaps the first bus bar. Bolts and nuts fasten the first bus bar to the second bus bar at positions corresponding to the through holes. Electrical junction boxes, through which large currents flow, tend to generate heat. Therefore, heat dissipation can sometimes be improved by connecting the first bus bar to a heat dissipation member made of aluminum or the like. In such cases, it has been considered to connect the underside of the first bus bar exposed through the through holes to the heat dissipation member via a heat dissipation gap filler such as silicone grease, as described in Patent Document 1. This arrangement improves heat dissipation while ensuring insulation between the first bus bar and the heat dissipation member.

[0003] Japanese Patent Application Laid-Open No. 2021-101493

[0004] However, in the above-described electrical junction box, the heads of the bolts or nuts protrude significantly from the underside of the first bus bar. Therefore, a large gap must be secured between the underside of the first bus bar and the heat dissipation member to ensure electrical insulation between the first bus bar and the heat dissipation member. This poses a problem in that an increased amount of heat dissipation gap filler must be used between the underside of the first bus bar and the heat dissipation member.

[0005] An object of the present disclosure is to provide an electrical junction box that allows for a reduction in the amount of heat dissipation gap filler used.

[0006] The electrical connection box disclosed herein comprises a resin base member having a through hole penetrating downward, a first bus bar arranged above the base member at a position corresponding to the through hole, a second bus bar arranged above the first bus bar and stacked thereon, and bolts and nuts that fasten the first bus bar and the second bus bar at a position corresponding to the through hole, and is arranged above a heat dissipation member, with the underside of the first bus bar exposed from the through hole being connected to the heat dissipation member via a heat dissipation gap filler, and the first bus bar has an accommodating portion that accommodates at least a portion of the head of the bolt or at least a portion of the nut.

[0007] According to the electrical junction box of the present disclosure, the amount of heat dissipation gap filler used can be reduced.

[0008] Fig. 1 is a schematic cross-sectional view showing a mounting structure of an electrical junction box according to an embodiment, and Fig. 2 is a schematic exploded cross-sectional view of the electrical junction box according to an embodiment.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described below. The present disclosure provides an electrical junction box: [1] An electrical junction box including: a resin base member having a through hole penetrating downward; a first bus bar arranged above the base member at a position corresponding to the through hole; a second bus bar arranged above the first bus bar and overlapping the first bus bar; and bolts and nuts fastening the first bus bar to the second bus bar at a position corresponding to the through hole, the electrical junction box being arranged above a heat dissipation member, and the underside of the first bus bar exposed from the through hole being connected to the heat dissipation member via a heat dissipation gap filler, and the first bus bar has an accommodation portion that accommodates at least a portion of a head of the bolt or at least a portion of the nut.

[0010] According to this configuration, the first bus bar has a housing portion that houses at least a part of the bolt head or at least a part of the nut, which prevents the bolt head or the nut from protruding too much from the underside of the first bus bar. This reduces the gap between the underside of the first bus bar and the heat dissipation member, thereby reducing the amount of heat dissipation gap filler used between the underside of the first bus bar and the heat dissipation member.

[0011] [2] In the above [1], the accommodation portion may accommodate at least a portion of the head. According to this configuration, the accommodation portion accommodates at least a portion of the head, so that the underside of the head is the lowest surface. This allows for a reduction in the amount of heat-dissipating gap filler used compared to a configuration in which the accommodation portion accommodates at least a portion of the nut. In other words, in a configuration in which the accommodation portion accommodates at least a portion of the nut, the bolt shank may protrude further downward from the nut. However, this can be avoided, and the gap between the underside of the first bus bar and the heat dissipating member can be further reduced. This allows for a further reduction in the amount of heat-dissipating gap filler used between the underside of the first bus bar and the heat dissipating member.

[0012] [3] In the above [1] or [2], the accommodating portion may accommodate the entire head or the nut so that the underside of the head or the underside of the nut is flush with the underside of the first bus bar.

[0013] According to this configuration, the accommodating portion accommodates the entire head or nut so that the underside of the head or the underside of the nut is flush with the underside of the first bus bar, thereby reducing the amount of heat dissipation gap filler used compared to a configuration that accommodates only part of the head or part of the nut.

[0014] [4] In any one of [1] to [3] above, the accommodation portion may be configured to fit tightly with the head or the nut without any gaps. According to this configuration, the accommodation portion is configured to fit tightly with the head or the nut without any gaps, so the amount of heat-dissipating gap filler used can be reduced compared to a configuration with a gap. In other words, in a configuration where the accommodation portion has a gap with the head or the nut, the heat-dissipating gap filler would get into the gap, increasing the amount of heat-dissipating gap filler used, but this can be avoided, so the amount of heat-dissipating gap filler used can be reduced.

[0015] [5] In any one of [1] to [4] above, the first bus bar may be thicker than the second bus bar. According to this configuration, the first bus bar is thicker than the second bus bar, making it easy to provide a receiving portion for receiving at least a portion of a bolt head or at least a portion of a nut. That is, for example, in a configuration in which the second bus bar arranged above the first bus bar is thicker than the first bus bar, it is difficult to provide a receiving portion in the thin first bus bar. In contrast, the first bus bar is thicker than the second bus bar, making it easy to provide a receiving portion.

[0016] [Details of the Embodiments of the Present Disclosure] Specific examples of the electrical junction box of the present disclosure will be described below with reference to the drawings. In each drawing, for the sake of convenience, some of the components may be exaggerated or simplified. Furthermore, the dimensional ratios of each part may differ between drawings. In this specification, "parallel," "orthogonal," and "circular" do not only refer to strictly parallel, orthogonal, or circular, but also include roughly parallel, orthogonal, or circular within the scope of the present embodiment's effects. The present invention is not limited to these examples, but is defined by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0017] 1 and 2, the electrical junction box 11 includes a base member 12, a first bus bar 13, a second bus bar 14, bolts 15, and nuts 16. The electrical junction box 11 of this embodiment is mounted on a vehicle, for example, and is connected between an FC stack that generates electricity using hydrogen and an inverter connected to a motor, through which a large current flows. Note that the electrical junction box 11 can be disposed in any orientation relative to the vehicle, but the following description will use an upper Z1 and a lower Z2 in the drawings.

[0018] (Configuration of base member 12) The base member 12 is made of resin. The base member 12 forms the bottom of the case of the electrical junction box 11. The electrical junction box 11 includes, for example, a lid (not shown) that is fixed to the base member 12 and forms the upper part of the case. The base member 12 has a through-hole 12a that penetrates downward Z2.

[0019] (Configuration of the first bus bar 13 and the second bus bar 14) The first bus bar 13 and the second bus bar 14 are metal plates. The first bus bar 13 is thicker than the second bus bar 14. Specifically, the first bus bar 13 in this embodiment is a thick copper bus bar that is thicker than the second bus bar 14. Note that the thicknesses of the first bus bar 13 and the second bus bar 14 are not accurately illustrated in the drawings, but are illustrated schematically. The electrical junction box 11 also includes electrical circuit components such as choke coils and capacitors (not shown) that are connected to the first bus bar 13 and the second bus bar 14.

[0020] As shown in Fig. 1, the first bus bar 13 is disposed above the base member 12 in the Z1 direction at a position corresponding to the through hole 12a. The first bus bar 13 has a first insertion hole 13a penetrating downward in the Z2 direction at a position opposite the through hole 12a. The first bus bar 13 also has a housing portion 13c recessed upward in the Z1 direction from the lower surface 13b at a position corresponding to the first insertion hole 13a. The first insertion hole 13a is in communication with the housing portion 13c.

[0021] The second bus bar 14 is disposed above the first bus bar 13 in the Z1 direction. The second bus bar 14 has a second insertion hole 14a penetrating downward in the Z2 direction at a position opposite the first insertion hole 13a.

[0022] (Configuration of bolt 15 and nut 16) The bolt 15 has a head 15a and a shank 15b. The head 15a extends in a flange-like shape from the end of the shank 15b. In this embodiment, the head 15a is formed in a circular shape and has multiple protrusions (not shown) in the circumferential direction that protrude radially outward. The shank 15b has a male thread formed on its outer peripheral surface so that it can be threaded into a female thread formed on the inner peripheral surface of the nut 16.

[0023] The head 15a is accommodated in the accommodation portion 13c of the first bus bar 13. More specifically, the shank 15b of the bolt 15 is inserted into the first insertion hole 13a from the lower side Z2 toward the upper side Z1 of the first bus bar 13, and the head 15a is accommodated in the accommodation portion 13c. The accommodation portion 13c in this embodiment accommodates the entire head 15a such that the lower surface 15c of the head 15a is flush with the lower surface 13b of the first bus bar 13.

[0024] The housing portion 13c is configured to fit tightly with the head portion 15a without any gaps. In this embodiment, the head portion 15a is press-fitted into the housing portion 13c. The housing portion 13c is configured to fit tightly with the head portion 15a, which has a protrusion (not shown), without any gaps, thereby preventing the bolt 15 from rotating.

[0025] 1, the nut 16 is screwed from above Z1 onto the shaft portion 15b inserted through the first insertion hole 13a and the second insertion hole 14a, so that the bolt 15 and the nut 16 fasten the first bus bar 13 and the second bus bar 14 together at a position corresponding to the through hole 12a.

[0026] (Mounting structure of the electrical connection box 11) As shown in Figure 1, the electrical connection box 11 is positioned above Z1 the heat dissipation member 21, and the lower surface 13b of the first bus bar 13 exposed from the through hole 12a is connected to the heat dissipation member 21 via a heat dissipation gap filler 22.

[0027] The heat dissipation member 21 is made of a metal material such as aluminum, which has high heat dissipation properties. The heat dissipation gap filler 22 is made of silicone grease, which has high thermal conductivity and insulation properties, and is paste-like and configured to be able to fill gaps and uneven surfaces.

[0028] The heat dissipation gap filler 22 is interposed between the heat dissipation member 21 and the lower surface 13b of the first bus bar 13 and the lower surface 15c of the head portion 15a exposed from the through hole 12a.

[0029] Next, the operation of the electrical junction box 11 configured as described above will be described. The electrical junction box 11 generates heat due to a large current flowing through the first bus bar 13 and the second bus bar 14. This heat is transferred to the heat dissipation member 21 via the heat dissipation gap filler 22 interposed between the lower surface 13b of the first bus bar 13 and the heat dissipation member 21, and is dissipated mainly from the heat dissipation member 21. This prevents the first bus bar 13 and the second bus bar 14, and ultimately the electrical junction box 11, from becoming too hot.

[0030] Next, the effects of the above embodiment are described below. (1) Because the first bus bar 13 has the accommodation portion 13c that accommodates the head portion 15a of the bolt 15, the head portion 15a can be prevented from protruding significantly from the lower surface 13b of the first bus bar 13. This allows the gap between the lower surface 13b of the first bus bar 13 and the heat dissipation member 21 to be reduced. This allows the amount of heat dissipation gap filler 22 used between the lower surface 13b of the first bus bar 13 and the heat dissipation member 21 to be reduced. Furthermore, because the distance from the lower surface 13b of the first bus bar 13 to the heat dissipation member 21 is reduced, heat dissipation is also improved.

[0031] (2) Because the accommodation portion 13c accommodates the head portion 15a, the lower surface 15c of the head portion 15a is the lowest surface. Therefore, the amount of heat dissipation gap filler 22 used can be reduced compared to, for example, a configuration in which the accommodation portion 13c accommodates at least a portion of the nut 16. That is, in a configuration in which the accommodation portion 13c accommodates at least a portion of the nut 16, the shank 15b of the bolt 15 may protrude further downward Z2 from the nut 16, but this can be avoided. Therefore, the gap between the lower surface 13b of the first bus bar 13 and the heat dissipation member 21 can be further reduced. Therefore, the amount of heat dissipation gap filler 22 used between the lower surface 13b of the first bus bar 13 and the heat dissipation member 21 can be further reduced.

[0032] (3) The accommodation portion 13c accommodates the entire head portion 15a so that the lower surface 15c of the head portion 15a is flush with the lower surface 13b of the first bus bar 13. Therefore, the amount of heat dissipation gap filler 22 used can be reduced compared to, for example, a configuration in which only a portion of the head portion 15a is accommodated.

[0033] (4) Because the accommodation portion 13c is configured to be in close contact with the head portion 15a without any gaps, the amount of heat dissipation gap filler 22 used can be reduced compared to a configuration with a gap. That is, in a configuration where the accommodation portion 13c has a gap between the head portion 15a and the accommodation portion 13c, the heat dissipation gap filler 22 gets into the gap, increasing the amount of heat dissipation gap filler 22 used, but this can be avoided, so the amount of heat dissipation gap filler 22 used can be reduced.

[0034] (5) Because the first bus bar 13 is thicker than the second bus bar 14, it is easy to provide the accommodation portion 13c that accommodates the head portion 15a of the bolt 15. That is, for example, if the second bus bar 14, which is arranged above the first bus bar 13 in the upper Z1 direction, is thicker than the first bus bar 13, it would be difficult to provide the accommodation portion 13c in the thin first bus bar 13. In contrast, because the first bus bar 13 is thicker than the second bus bar 14, it is easy to provide the accommodation portion 13c.

[0035] This embodiment can be modified as follows. This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs. In the above embodiment, the accommodation portion 13c accommodates the head 15a of the bolt 15, but this is not limited to this, and the accommodation portion 13c may accommodate at least a portion of the nut 16. Even in this configuration, compared to a configuration in which the entire nut 16 is disposed below the lower surface 13b of the first bus bar 13 at Z2, the nut 16 can be prevented from protruding significantly from the lower surface 13b of the first bus bar 13, and the amount of heat dissipation gap filler 22 used can be reduced.

[0036] Furthermore, when accommodating portion 13c is configured to accommodate nut 16, accommodating portion 13c may be configured to accommodate the entire nut 16 so that the lower surface of nut 16 is flush with lower surface 13b of first bus bar 13. Furthermore, when accommodating portion 13c is configured to accommodate nut 16, accommodating portion 13c may be configured to be in close contact with nut 16 without any gaps.

[0037] In the above embodiment, the accommodating portion 13c accommodates the entire head 15a so that the lower surface 15c of the head 15a is flush with the lower surface 13b of the first bus bar 13. However, this is not limited to this, and the accommodating portion 13c may be configured to accommodate, for example, only a portion of the head 15a.

[0038] In the above embodiment, the housing portion 13c is configured to be in close contact with the head portion 15a without any gap, but this is not limited thereto and the housing portion 13c may be configured to have a gap between the head portion 15a and the housing portion 13c. In this case, the housing portion 13c is also preferably configured to prevent the bolt 15 from rotating.

[0039] In the above embodiment, the first bus bar 13 is thicker than the second bus bar 14 , but this is not limited to this. The first bus bar 13 may be the same thickness as the second bus bar 14 or thinner than the second bus bar 14 .

[0040] In the above embodiment, the head 15a of the bolt 15 is formed in a circular shape and has multiple protrusions (not shown) in the circumferential direction that protrude radially outward, but this is not limited to this and the head 15a may be formed in a hexagonal or rectangular shape, for example.

[0041] In the above embodiment, the electrical connection box 11 is, for example, mounted on a vehicle and connected between an FC stack that generates electricity using hydrogen and an inverter connected to a motor, but this is not limited to this and the box may be connected to other electrical equipment.

[0042] In the illustrated embodiment, the pair of bolts 15 and nuts 16 is an example of a fastener that fastens the first bus bar 13 and the second bus bar 14. The accommodating portion 13c of the first bus bar 13 is an example of a fastener receiving pit, and may be configured to be completely or at least partially filled with the pair of bolts 15 and nuts 16 (fasteners). In the embodiment shown in FIG. 1 , the pair of first bus bar 13 and second bus bar 14 fastened by the bolts 15 and nuts 16 is an example of a heat dissipation source or a stack of multiple metal plates that generate heat when current is applied. The first bus bar 13 may be a trunk bus bar, and the second bus bar 14 may be a branch bus bar.

[0043] As shown in FIG. 1 , the base member 12 may have a busbar support surface that supports the underside of the first busbar 13 by directly contacting a portion of the underside of the first busbar 13 at a position other than the accommodation portion 13c of the first busbar 13. In the embodiment shown in FIG. 1 , the through-hole 12a of the base member 12 is provided at a position corresponding to the accommodation portion 13c of the first busbar 13 and is an example of a heat dissipation path window that partially exposes the underside of the first busbar 13 and receives the heat dissipation gap filler 22. In the embodiment shown in FIG. 1 , the heat dissipation gap filler 22 is in direct contact with the first busbar 13 and the heat dissipation member 21, and is configured to transfer or release heat from the first busbar 13 and / or the second busbar 14 from the first busbar 13 to the heat dissipation member 21 via the heat dissipation gap filler 22. This may be referred to as a heat dissipation path or a heat dissipation path spacer. The heat dissipation gap filler 22 may have higher thermal conductivity than the base member 12. As shown in FIG. 1 , the heat dissipation member 21 of the embodiment may include a heat receiving surface or area that is in direct contact with the heat dissipation gap filler 22 to receive heat from the first bus bar 13 and / or the second bus bar 14 from the heat dissipation gap filler 22.

[0044] REFERENCE SIGNS LIST 11 Electrical junction box 12 Base member 12a Through hole 13 First bus bar 13a First insertion hole 13b Lower surface 13c Receiving portion 14 Second bus bar 14a Second insertion hole 15 Bolt 15a Head portion 15b Shank portion 15c Lower surface 16 Nut 21 Heat dissipation member 22 Heat dissipation gap filler Z1 Upper Z2 Lower

Claims

1. An electrical junction box comprising: a resin base member having a through hole penetrating downward; a first bus bar arranged above the base member at a position corresponding to the through hole; a second bus bar arranged above the first bus bar and stacked thereon; and bolts and nuts fastening the first bus bar to the second bus bar at a position corresponding to the through hole, the electrical junction box being arranged above a heat dissipation member, with an underside of the first bus bar exposed from the through hole connected to the heat dissipation member via a heat dissipation gap filler, wherein the first bus bar has an accommodating portion that accommodates at least a part of the head of the bolt or at least a part of the nut.

2. The electrical connection box according to claim 1, wherein the housing portion houses at least a portion of the head portion.

3. The electrical connection box according to claim 1, wherein the accommodating portion accommodates the entire head or the nut such that the underside of the head or the underside of the nut is flush with the underside of the first bus bar.

4. The electrical connection box according to claim 1, wherein the accommodating portion is configured to fit tightly with the head or the nut without any gaps.

5. The electrical junction box according to claim 1, wherein the first bus bar is thicker than the second bus bar.

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