Electrical connection box

Abstract

This electrical connection box (10) comprises: a case (11); a heat-generating component (12) accommodated inside the case (11); a bus bar (13) that receives heat from the heat-generating component (12); and a heat transfer sheet (14) that transfers the heat from the bus bar (13) to the outside of the case (11). An opening end (22) is formed in a bottom wall (19) of the case (11). The bus bar (13) has a heat transfer part (25) facing the opening end (22). An insulating film (15) is interposed between the heat transfer part (25) and the heat transfer sheet (14). The insulating film (15) is harder than the heat transfer sheet (14).

Description

Electrical junction box

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

[0002] The battery shut-off unit described in Patent Document 1 includes a relay, a bus bar connected to the relay, a heat sink fastened together with the bus bar, and an insulating sheet interposed between the heat sink and a cooler (hereinafter referred to as a "heat transfer sheet"). The heat transfer sheet has insulating properties and a heat transfer function. When the relay operates and current flows through the bus bar, heat is generated in the bus bar. The heat generated in the bus bar is transferred to the heat sink, and then radiated to the cooler via the heat transfer sheet. The bus bar has a portion facing the heat transfer sheet.

[0003] International Publication No. 2023 / 162880

[0004] In the battery shut-off unit of Patent Document 1, if a foreign matter enters between the cooler and the heat transfer sheet, the foreign matter may break through the heat transfer sheet and come into contact with the bus bar facing the heat transfer sheet. Therefore, it is considered that the technology of Patent Document 1 has room for improvement from the viewpoint of the insulation performance of the bus bar. Accordingly, an object of the present disclosure is to provide an electrical junction box capable of improving the insulation performance of the bus bar.

[0005] The electrical junction box of the present disclosure includes a case, a heat-generating component housed inside the case, a bus bar that receives heat from the heat-generating component, and a heat transfer sheet that transfers heat from the bus bar to the outside of the case, wherein an opening is opened in a bottom wall of the case, the bus bar has a heat transfer portion facing the opening, an insulating film is interposed between the heat transfer portion and the heat transfer sheet, and the insulating film is a film harder than the heat transfer sheet.

[0006] According to the present disclosure, it is possible to provide an electrical junction box capable of improving the insulation performance of the bus bar.

[0007] Fig. 1 is an enlarged cross-sectional view of essential parts of the electrical junction box according to Embodiment 1. Fig. 2 is an enlarged bottom view of essential parts of the electrical junction box according to Embodiment 1.

[0008] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described. The electrical junction box of the Disclosure comprises (1) a case, a heat-generating component housed inside the case, a busbar that receives heat from the heat-generating component, and a heat transfer sheet that transmits heat from the busbar to the outside of the case, wherein an opening is provided in the bottom wall of the case, the busbar has a heat transfer portion facing the opening, an insulating film is interposed between the heat transfer portion and the heat transfer sheet, and the insulating film is harder than the heat transfer sheet. According to the configuration of (1) above, the insulating film, which is harder than the heat transfer sheet, protects the busbar from foreign matter, thereby ensuring the insulation of the busbar.

[0009] (2) In the electrical connection box described in (1) above, it is preferable that the insulating film covers the gap formed between the heat transfer section facing the opening and the bottom wall from the outside. According to the configuration in (2) above, it is possible to prevent foreign matter from entering the inside of the case through the gap.

[0010] (3) In the electrical junction box described in (2) above, it is preferable that the insulating film is adhered to the heat transfer section and the heat transfer sheet, respectively. According to the configuration in (3) above, the insulating film, busbar and heat transfer sheet can be easily integrated.

[0011] (4) In the electrical junction box described in any of (1) to (3) above, it is preferable that an easily replaceable film is interposed between the mounting surface on which the case is installed and the heat transfer sheet. According to the configuration of (4) above, the easily replaceable film makes it easy to remove the electrical junction box from the mounting surface.

[0012] [Details of Embodiments of the Disclosure] Specific examples of embodiments of the disclosure will be described below with reference to the drawings. However, the present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of the equivalents of the claims are intended to be included. The electrical junction box 10 according to Embodiment 1 of the Disclosure is provided in a battery pack 50 mounted in a vehicle such as an electric vehicle. In Figure 1, X, Y, and Z represent the front, right, and up, respectively. These directional references are for convenience and do not necessarily coincide with the directional references when the electrical junction box 10 is mounted in a vehicle.

[0013] [Embodiment 1] As shown in Figure 1, the electrical junction box 10 is installed on the mounting surface 51 (cooling surface), which is the upper surface of the battery pack 50 (only a part of the battery pack 50 is shown for illustrative purposes). The battery pack 50 is made of metal and has a box shape. The mounting surface 51 is flat. The electrical junction box 10 comprises a box-shaped case 11, a heat-generating component 12 housed inside the case 11, a busbar 13 that receives heat from the heat-generating component 12, and a heat transfer sheet 14 that transmits heat from the busbar 13 to the outside of the case 11. An insulating film 15 is interposed between the heat transfer section 25 of the busbar 13 (described later) and the heat transfer sheet 14. In addition, an easily replaceable film 16 is interposed between the mounting surface 51 and the heat transfer sheet 14.

[0014] In this embodiment 1, the heat-generating component 12 is a relay. The heat-generating component 12 has a box shape. The heat-generating component 12 generates heat when operating and transfers the heat to the busbar 13. The busbar 13 is screwed to the heat-generating component 12 and is electrically and mechanically connected.

[0015] The case 11 is made of insulating resin and has an upper case 17 and a lower case 18. The upper case 17 fits over the lower case 18 from above. The upper case 17 has a peripheral wall 28 and is open to the bottom. The heat-generating component 12 is placed in the open space of the upper case 17. The lower case 18 has a bottom wall 19 and is open to the top.

[0016] The bottom wall 19 has an opening 20 that penetrates the bottom wall 19 vertically and opens downwards. As shown in Figure 1, the heat transfer section 25 of the busbar 13 and a part of the connecting section 26, which will be described later, are arranged inside the opening 20. The lower end of the opening 20 is configured as an opening end 22. The opening end 22 is formed along the outer shape of the lower surface of the heat transfer section 25. The opening end 22 is an edge that surrounds the heat transfer section 25.

[0017] The busbar 13 is formed by bending a metal plate using a press or the like. As shown in Figure 1, the busbar 13 consists of a first busbar 23 that is screwed to the heat-generating component 12 and a second busbar 24 that contacts the first busbar 23. The first busbar 23 is positioned along the rear surface of the heat-generating component 12 and has a shape that is bent backward. The backward bent portion of the first busbar 23 contacts the second busbar 24. The first busbar 23 is screwed and fixed to the upper case 17 together with the second busbar 24.

[0018] The second busbar 24 has a heat transfer section 25 extending in the front-rear direction, a pair of connecting sections 26 rising from both ends of the heat transfer section 25 in the front-rear direction, and a pair of straight sections 27 bending and connecting to the upper ends of each connecting section 26. The front straight section 27 extends forward from the upper end of the front connecting section 26. The rear straight section 27 extends rearward from the upper end of the rear connecting section 26.

[0019] Each straight section 27 is positioned with its plate surface facing vertically. The rear straight section 27 makes surface contact with the rearward bent portion of the first busbar 23. Of the rear straight section 27, the portion in front of the contact portion with the first busbar 23 faces the bottom surface of the heat-generating component 12. The rear straight section 27 is longer in the front-to-back direction than the front straight section 27. The front straight section 27 is screwed in together with other conductive members such as busbars.

[0020] Each connecting portion 26 extends vertically with its plate surface facing the front-to-back direction. The portion of each connecting portion 26 below the connection point with each straight portion 27 is positioned inside the opening 20. The lower part of each connecting portion 26 is positioned along the inner surface of the opening 20 (more specifically, the inner surfaces facing each other in the front-to-back direction) while having a gap between it and the inner surface.

[0021] The heat transfer section 25 extends in the front-to-back direction with its plate surface facing vertically. The heat transfer section 25 is positioned inside the opening 20. The front-to-back dimension of the heat transfer section 25 is smaller than the front-to-back dimension of the heat-generating component 12. The lower surface of the heat transfer section 25 faces the opening end 22 and is in contact with the insulating film 15. The heat transfer section 25 is not in contact with the bottom wall 19. A gap 21 is formed between the heat transfer section 25 facing the opening end 22 and the bottom wall 19.

[0022] The insulating film 15 is a thin film made of insulating resin. The insulating film 15 is positioned below the opening end 22 with its film surface facing vertically. Both the upper and lower surfaces of the insulating film 15 are adhesive. As a result, the insulating film 15 adheres to the heat transfer section 25 on its upper side and to the heat transfer sheet 14 on its lower side. As shown in Figure 2, the front-to-back dimension of the insulating film 15 is larger than the front-to-back opening dimension of the opening end 22. The left-to-right dimension of the insulating film 15 is larger than the left-to-right opening dimension of the opening end 22. In short, the insulating film 15 completely covers the opening end 22 from below. As a result, the gap 21 is also covered from below by the insulating film 15 (see Figure 1).

[0023] The insulating film 15 is harder than the heat transfer sheet 14 and has sufficient hardness to withstand interference from foreign objects that penetrate the heat transfer sheet 14, for example. The material of the insulating film 15 can be any material that has insulating properties and covers the heat transfer part 25, and suitable materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytetrafluoroethylene (PTFE), polycarbonate (PC), and polyimide (PI). Furthermore, the thickness of the insulating film 15 is preferably relatively thin in order to advantageously achieve thermal conductivity from the heat transfer part 25 to the installation surface 51, and suitable materials include a thickness of 500 μm or less, more preferably 250 μm or less.

[0024] The heat transfer sheet 14 is a sheet material formed in a rectangular shape when viewed from above. In this embodiment 1, as shown in Figure 1, the heat transfer sheet 14 is positioned outside (below) the opening end 22 of the lower case 18. The heat transfer sheet 14 is in contact with the insulating film 15 in the area corresponding to the heat transfer section 25.

[0025] The heat transfer sheet 14 is made of a thermally conductive synthetic resin material, such as acrylic, other acrylic-based materials, or silicone-based materials. The heat transfer sheet 14 is flexible and softer than the insulating film 15. The heat transfer sheet 14 also has insulating properties.

[0026] The thickness of the heat transfer sheet 14 is greater than the thickness of the insulating film 15, for example, twice or more the thickness of the insulating film 15, preferably five times or more the thickness of the insulating film 15. The heat transfer sheet 14 is smaller than the insulating film 15 in the left-right and front-back directions. In other words, the heat transfer sheet 14 is covered by the insulating film 15. In this embodiment 1, since there is no air layer between the insulating film 15 and the installation surface 51 and the heat transfer sheet 14 is provided, the thermal conductivity can be improved.

[0027] An easily replaceable film 16 is interposed between the mounting surface 51 and the heat transfer sheet 14. The easily replaceable film 16 is formed as a thin film with insulating properties. The thickness of the easily replaceable film 16 is less than the thickness of the heat transfer sheet 14. As shown in Figure 2, the easily replaceable film 16 is positioned outside (below) the opening end 22 of the lower case 18. Also, in the left-right and front-back directions, the easily replaceable film 16 is smaller than the insulating film 15 and larger than the heat transfer sheet 14. When the electrical junction box 10 is removed from the mounting surface 51, the easily replaceable film 16 adheres closely to the heat transfer sheet 14 and can be peeled off from the mounting surface 51.

[0028] Now, in the electrical junction box 10 according to this embodiment 1, the heat transfer path from the heat-generating component 12 to the installation surface 51 will be described below. First, when the heat-generating component 12 operates, heat is generated. The heat generated by the heat-generating component 12 is transferred from the heat-generating component 12 to the first busbar 23. The heat transferred to the first busbar 23 is then transferred to the second busbar 24 via the contact portion between the first busbar 23 and the second busbar 24. Subsequently, this heat is transferred from the heat transfer portion 25 of the second busbar 24 to the insulating film 15. The heat transferred to the insulating film 15 is then dissipated to the installation surface 51 via the heat transfer sheet 14 and the easily replaceable film 16.

[0029] The electrical junction box 10 of this embodiment 1 comprises a case 11, a heat-generating component 12 housed inside the case 11, a busbar 13 that receives heat from the heat-generating component 12, and a heat transfer sheet 14 that transmits heat from the busbar 13 to the outside of the case 11. An opening 20 is provided in the bottom wall 19 of the case 11 (lower case 18). The busbar 13 (second busbar 24) has a heat transfer portion 25 facing the opening 20. An insulating film 15 is interposed between the heat transfer portion 25 and the heat transfer sheet 14. The insulating film 15 is a harder film than the heat transfer sheet 14. If foreign matter were to enter the electrical junction box 10, there would be a concern that the foreign matter would penetrate the heat transfer sheet 14. However, in the case of this embodiment 1, even if foreign matter were to penetrate the heat transfer sheet 14, the foreign matter would interfere with the insulating film 15, preventing further penetration. This protects the heat transfer section 25 (bus bar 13) and, consequently, ensures the insulation of the bus bar 13.

[0030] In this embodiment 1, the insulating film 15 covers the gap 21 formed between the heat transfer section 25 facing the open end 22 (opening 20) and the bottom wall 19 from the outside (below) of the case 11. This prevents foreign matter from entering the case 11 from the outside through the gap 21.

[0031] In this embodiment 1, the insulating film 15 is adhered to the heat transfer section 25 and the heat transfer sheet 14, respectively. This allows the insulating film 15, the busbar 13, and the heat transfer sheet 14 to be easily integrated into one unit.

[0032] In this embodiment 1, an easily replaceable film 16 is interposed between the mounting surface 51 on which the case 11 is installed and the heat transfer sheet 14. For example, if a filler such as a gap filler is interposed between the mounting surface and the heat transfer sheet, and the filler hardens, the filler may stick to the mounting surface when removing the electrical junction box from the mounting surface, making it difficult to remove the electrical junction box. Also, if the heat transfer sheet and the mounting surface are in direct contact, the heat transfer sheet may stick to the mounting surface. In contrast to these, when removing the electrical junction box 10 from the mounting surface 51, the easily replaceable film 16 is a film that adheres closely to the heat transfer sheet 14 and can be peeled off from the mounting surface 51. This makes it possible to avoid difficulties in removing the electrical junction box 10.

[0033] [Other Embodiments of the Disclosure] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. In Embodiment 1, the gap 21 formed between the heat transfer section 25 facing the open end 22 and the bottom wall 19 was covered from the outside by an insulating film 15. In contrast, in other embodiments, the insulating film may not cover the gap from the outside, and a heat transfer sheet may cover the gap from the outside. The insulating film only needs to cover the busbars so as to protect them from foreign matter, for example, it may only cover the lower surface of the heat transfer section. In Embodiment 1, the case 11 was composed of an upper case 17 and a lower case 18 as separate components. In contrast, in other embodiments, the case may be composed of an upper case and a lower case as a single unit. In Embodiment 1, the open end 22 was formed along the outer shape of the heat transfer section 25. In contrast, in other embodiments, the open end may not be formed along the outer shape of the heat transfer section, for example, it may be a large opening extending closer to the peripheral wall. In this first embodiment, the busbar 13 was provided as two separate components: a first busbar 23 and a second busbar 24. In contrast, in other embodiments, the busbar may be provided as a single unit.

[0034] 10... Electrical junction box 11... Case 12... Heat-generating component 13... Busbar 14... Heat transfer sheet 15... Insulating film 16... Easily replaceable film 17... Upper case 18... Lower case 19... Bottom wall 20... Opening 21... Gap 22... Open end 23... First busbar 24... Second busbar 25... Heat transfer section 26... Connection section 27... Straight section 28... Peripheral wall 50... Battery pack 51... Mounting surface

Claims

1. An electrical connection box comprising a case, a heat-generating component housed inside the case, a busbar that receives heat from the heat-generating component, and a heat transfer sheet that transmits heat from the busbar to the outside of the case, wherein an opening is provided in the bottom wall of the case, the busbar has a heat transfer portion facing the opening, an insulating film is interposed between the heat transfer portion and the heat transfer sheet, and the insulating film is a film harder than the heat transfer sheet.

2. The electrical connection box according to claim 1, wherein the insulating film covers the gap formed between the heat transfer section facing the opening and the bottom wall from the outside.

3. The electrical connection box according to claim 2, wherein the insulating film is adhered to the heat transfer section and the heat transfer sheet, respectively.

4. An electrical connection box according to any one of claims 1 to 3, wherein an easily replaceable film is interposed between the mounting surface on which the case is installed and the heat transfer sheet.

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