Electrical junction box and method of producing electrical junction box

Abstract

According to one embodiment of the present disclosure, provided is an electrical junction box making it possible to curb a size increase and ensure heat dissipation properties and creepage distance. An electrical junction box (10) is provided with: a lower case (20) having a bottom (21) in which a through hole (23) is provided; an upper case (30) assembled onto the lower case; a relay (40) accommodated in the interior of the lower case and the upper case; a busbar (60) connected to the relay; an insulating film (70) disposed on the bottom (21) so as to cover the through hole (23) and having an upper surface contacting the busbar; and a heat dissipation sheet (80) that is provided so as to penetrate the through hole (23) while being in contact with the insulating film, and that is in contact with an external cooling member (90). The insulating film (70) comprises a creepage distance constituting section (73) which is provided on the bottom (21) from an edge (71) of the insulating film (70) to an opening end (23a) of the through hole (23), thereby constituting a section of the creepage distance between the busbar (60) and the external cooling member (90).

Description

Electrical junction box and manufacturing method for electrical junction box

[0001] The present disclosure relates to an electrical junction box and a method for manufacturing an electrical junction box.

[0002] Conventionally, there has been an electrical junction box that includes a resin case and an electric circuit component, such as a relay, held in the resin case (see, for example, Patent Document 1). A bus bar is connected to the electric circuit component. The bus bar is in contact with an external cooling member, such as a chassis of a vehicle body, via an insulating film and a heat dissipation sheet, thereby ensuring good heat dissipation.

[0003] JP 2014-79093 A

[0004] However, in the electrical junction box described above, the creepage distance between the bus bar and the external cooling member is the same as the thickness of the insulating film and the heat dissipation sheet, so there is a risk that the insulation between the bus bar and the external cooling member may not be ensured. Furthermore, for example, simply making the insulating film protrude significantly from the underside of the bus bar would result in an increase in the overall size of the box.

[0005] An object of the present disclosure is to provide an electrical junction box that can prevent an increase in size while ensuring heat dissipation properties and creepage distance, and a method for manufacturing the electrical junction box.

[0006] The electrical junction box of the present disclosure comprises a lower case having a bottom with a through hole, an upper case assembled to the lower case, electrical circuit components housed inside the lower case and the upper case, a bus bar connected to the electrical circuit components, an insulating film arranged on the bottom to cover the through hole and with its upper surface in contact with the bus bar, and a heat dissipation sheet arranged to pass through the through hole while in contact with the insulating film and in contact with an external cooling member, wherein the insulating film has a creepage distance forming portion that forms part of the creepage distance between the bus bar and the external cooling member by being arranged on the bottom from the edge of the insulating film to the open end of the through hole.

[0007] According to the electrical junction box and the manufacturing method of the electrical junction box of the present disclosure, it is possible to prevent the size from increasing while ensuring heat dissipation and creepage distance.

[0008] Fig. 1 is a schematic cross-sectional view of an electrical junction box according to an embodiment. Fig. 2 is a partially enlarged schematic cross-sectional view of the electrical junction box according to the embodiment. Fig. 3 is a schematic cross-sectional view for explaining a method for manufacturing the electrical junction box according to the embodiment. Fig. 4 is a partially enlarged schematic cross-sectional view of an electrical junction box according to a comparative example.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described below. The electrical junction box of the present disclosure includes: [1] a lower case having a bottom with a through hole formed therein, an upper case assembled to the lower case, electric circuit components housed inside the lower case and the upper case, a bus bar connected to the electric circuit components, an insulating film disposed on the bottom to close the through hole and having an upper surface in contact with the bus bar, and a heat dissipation sheet disposed in contact with the insulating film and passing through the through hole, the heat dissipation sheet being in contact with an external cooling member, the insulating film having a creepage distance forming portion that forms a part of the creepage distance between the bus bar and the external cooling member by being disposed on the bottom from an edge of the insulating film to an open end of the through hole.

[0010] According to this configuration, the bus bar contacts the external cooling member via the insulating film and the heat dissipation sheet, ensuring good heat dissipation. Furthermore, the insulating film has a creepage distance-forming portion that constitutes part of the creepage distance between the bus bar and the external cooling member by being disposed on the bottom of the lower case from its edge to the opening end of the through-hole. This allows for a longer creepage distance while minimizing the size of the electrical junction box. That is, the insulating film has a creepage distance-forming portion extending from its edge to the opening end of the through-hole. This configuration allows for a longer creepage distance than, for example, a configuration in which an insulating film and a heat dissipation sheet are simply interposed between the bus bar and the external cooling member, resulting in a creepage distance equal to the thickness of the insulating film and the heat dissipation sheet. Furthermore, for example, if an insulating film is attached to the underside of the bus bar while exposing the bus bar below the through-hole, ensuring the creepage distance requires, for example, the insulating film to protrude significantly from the bus bar. This would result in, for example, a large amount of unnecessary space being created inside the lower case and the upper case, and would increase the size of the electrical junction box, but this configuration can be prevented.

[0011] [2] In the above [1], the bus bar may be in contact with the insulating film so as to be flush with an edge of the insulating film. With this configuration, the bus bar is in contact with the insulating film so as to be flush with the edge of the insulating film, which can minimize the creation of large, unnecessary spaces inside the lower case and the upper case. In other words, compared to a configuration in which the insulating film protrudes from the bus bar, for example, the size of the device can be reduced.

[0012] [3] In the above [1] or [2], the lower case may have a wall portion erected to face the edge of the insulating film so that a path including the creepage distance forming portion becomes the creepage distance between the bus bar and the external cooling member.

[0013] According to this configuration, the lower case has a wall portion that faces the edge of the insulating film so that the path including the creepage distance forming portion becomes the creepage distance between the bus bar and the external cooling member, so there is no need for the lower case to protrude significantly from the bus bar, thereby preventing the device from becoming too large.

[0014] [4] In any one of [1] to [3] above, the electrical circuit components may be provided in a plurality, and fixing holes may be provided at positions between the electrical circuit components on the bottom, and the upper case may have fixing portions that pass through the fixing holes and are fixed to the external cooling member.

[0015] According to this configuration, fixing holes are provided in the bottom portion at positions between the electric circuit components, and the upper case has fixing portions that penetrate the fixing holes and are fixed to the external cooling member, so the electric junction box can be stably fixed to the external cooling member with a small number of fixing points. Furthermore, with this configuration, it is possible to prevent the creation of large, unnecessary spaces inside the lower and upper cases, even between the electric circuit components, and therefore it is possible to prevent the electric junction box from becoming larger.

[0016] [5] In any one of [1] to [4] above, a plurality of the electric circuit components may be provided, and the insulating film may have a plurality of component corresponding portions corresponding to each of the electric circuit components.

[0017] According to this configuration, the insulating film has a plurality of component-receiving portions corresponding to the respective electric circuit components, so the number of components can be reduced compared to a configuration in which the components are provided separately for each electric circuit component, which makes it easier to assemble the insulating film, for example.

[0018] The manufacturing method of the electrical junction box of the present disclosure is [6] a manufacturing method of any one of the electrical junction boxes [1] to [5] above, comprising a film fixing step of fixing the insulating film to the lower case, a circuit fixing step of fixing the electrical circuit components and the bus bar to the upper case, and a case assembling step of assembling the lower case and the upper case after the film fixing step and the circuit fixing step so that the bus bar and the insulating film come into contact with each other.

[0019] According to this method, an insulating film is fixed to the lower case in a film fixing process, and electrical circuit components and a bus bar are fixed to the upper case in a circuit fixing process. Then, after the film fixing process and the circuit fixing process, the lower case and the upper case are assembled in a case assembling process so that the bus bar and the insulating film are in contact with each other. This allows the electrical circuit components, the bus bar, and the insulating film to be housed inside the lower case and the upper case, and each component to be easily assembled in a desired position. For example, compared to a method in which the lower case is assembled to the upper case with the electrical circuit components, the bus bar, and the insulating film fixed to the upper case, this method allows the insulating film to be assembled accurately and easily in a desired position on the lower case. Furthermore, this configuration allows for suppressing size increase while ensuring heat dissipation and creepage distance.

[0020] [Details of the Embodiments of the Present Disclosure] Specific examples of the present disclosure will be described below with reference to the drawings. In each drawing, for the convenience of explanation, some of the configurations may be exaggerated or simplified. Furthermore, the dimensional proportions of each part may differ from one drawing to another. Furthermore, the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0021] 1, the electrical junction box 10 includes a lower case 20, an upper case 30, a relay 40 and a fuse 50 as electrical circuit components, a bus bar 60, an insulating film 70, and a heat dissipation sheet 80. The electrical junction box 10 of this embodiment is fixed to, for example, an external cooling member 90 provided in a vehicle. The external cooling member 90 may be, for example, an aluminum plate with high heat dissipation properties, or a water-cooled member through which cooling water is circulated.

[0022] (Configuration of the Lower Case 20) The lower case 20 is made of a resin material. The lower case 20 has a bottom 21 and a wall 22. The bottom 21 is formed in a plate shape. The bottom 21 is provided with a through hole 23 and a fixing hole 24. The through hole 23 is provided below the portions of the bottom 21 where the relay 40 and the fuse 50 are respectively disposed. The fixing hole 24 is provided at a position on the bottom 21 between the relay 40 and the fuse 50. Note that in FIG. 1 , the lower case 20 is illustrated as being divided into two portions, one disposed below the relay 40 and the other disposed below the fuse 50, with the fixing hole 24 sandwiched between them, but these portions are connected at a position not shown. The wall 22 is provided upright on the outer edge of the bottom 21 and the edge of the fixing hole 24.

[0023] (Configuration of the upper case 30) The upper case 30 is made of a resin material. The upper case 30 is assembled to the lower case 20. The upper case 30 has a side wall 31, an upper wall 32, and a fixing portion 33. The side wall 31 is formed to cover the outside of the wall portion 22 of the lower case 20. The upper wall 32 is formed to connect the upper ends of the side walls 31 and cover the relays 40 and the fuses 50. The fixing portion 33 is formed so as to pass through the fixing holes 24 of the lower case 20 and be fixable to the external cooling member 90. The fixing portion 33 in this embodiment has a screw hole 33a, and is fixed to the external cooling member 90 by a screw 34 that passes through the screw hole 33a and screws into the external cooling member 90.

[0024] (Configuration of the relay 40, fuse 50, and bus bar 60) The relay 40 and the fuse 50 are electric circuit components housed inside the lower case 20 and the upper case 30. A bus bar 60 is connected to each of the relay 40 and the fuse 50. The bus bar 60 is a metal plate. The bus bar 60 extends downward below each of the relay 40 and the fuse 50. The bus bar 60 is also connected to other electric circuit components via other bus bars (not shown). Note that FIG. 1 illustrates one of the pair of bus bars 60 connected to the relay 40 being fixed by a screw 41. The relay 40 and the fuse 50 are also fixed to the upper case 30 by a fixing structure (not shown). The bus bar 60 is fixed to the relay 40 and the fuse 50, and thereby fixed to the upper case 30.

[0025] (Configuration of Insulating Film 70) The insulating film 70 is, for example, an insulating resin film. The insulating film 70 is disposed on the bottom 21 so as to cover the through-holes 23 of the lower case 20. The upper surface of the insulating film 70 is in contact with the bus bar 60. As shown in FIG. 2 , in this embodiment, the bus bar 60 is in contact with the insulating film 70 so as to be flush with an edge 71 of the insulating film 70. In other words, the insulating film 70 is configured to cover the entire lower surface of the bus bar 60 while not protruding from the bus bar 60 when viewed from above. Note that in FIG. 1 , the insulating film 70 is illustrated as being divided into two portions, one disposed below the relay 40 and the other disposed below the fuse 50, with the fixing holes 24 sandwiched therebetween; however, these portions are connected at a position not shown. That is, the insulating film 70 of this embodiment is a single film having a plurality of component-corresponding portions 72 corresponding to the relays 40 and the fuse 50, respectively.

[0026] (Configuration of heat dissipation sheet 80) The heat dissipation sheet 80 is, for example, a thermally conductive silicone sheet. The heat dissipation sheets 80 are provided corresponding to the respective through-holes 23 of the lower case 20. The heat dissipation sheets 80 are provided so as to pass through the through-holes 23 of the lower case 20 while being in contact with the insulating film 70, and are in contact with the external cooling member 90. The heat dissipation sheet 80 is configured to be sandwiched between the insulating film 70 and the external cooling member 90 when the fixing portions 33 of the upper case 30 are fixed to the external cooling member 90 with the screws 34, i.e., when the electrical junction box 10 is fixed to the external cooling member 90.

[0027] 2 , the insulating film 70 has a creepage distance forming portion 73 that is disposed on the bottom 21 from the edge 71 of the insulating film 70 to the opening end 23 a of the through-hole 23 and thereby forms part of the creepage distance between the bus bar 60 and the external cooling member 90. In other words, the insulating film 70 has the creepage distance forming portion 73 in a range H from the edge 71 of the insulating film 70 to the opening end 23 a of the through-hole 23. The creepage distance between the bus bar 60 and the external cooling member 90 refers to the distance of the path that passes through the end face of the edge 71 of the insulating film 70, the creepage distance forming portion 73 (i.e., the underside of the insulating film 70), and the end face of the heat dissipation sheet 80, from the bus bar 60 to the external cooling member 90. As shown in FIG. 1 , the creepage distance forming portion 73 is provided in all positions of the insulating film 70 that are close to each of the bus bars 60.

[0028] Furthermore, the wall 22 of the lower case 20 is erected to face the edge 71 of the insulating film 70 so that the path including the creepage distance forming portion 73 is the creepage distance between the bus bar 60 and the external cooling member 90. That is, for example, if the gap between the lower case 20 and the external cooling member 90 is extremely small or they are in contact with each other and the height of the wall 22 is low, there is a risk that the creepage distance, i.e., the shortest distance along the surface of the insulator, will be a path that does not include the creepage distance forming portion 73, for example, a path that passes through the outer surface of the lower case 20 that faces the inner surface of the upper case 30. To prevent this, the position and height of the wall 22 are set so that the path including the creepage distance forming portion 73 is the creepage distance between the bus bar 60 and the external cooling member 90.

[0029] (Method for Manufacturing Electrical Junction Box 10) Next, a description will be given of a method for manufacturing the electrical junction box 10 configured as described above. The method for manufacturing the electrical junction box 10 includes a film fixing step, a circuit fixing step, a case assembling step, and a heat dissipation sheet fixing step.

[0030] 3, in the film fixing step, the insulating film 70 is fixed to the lower case 20. More specifically, the insulating film 70 is fixed onto the bottom 21 so as to cover the through-hole 23 of the lower case 20. Note that while FIGS. 1 and 3 are end views that schematically illustrate a cross section of the electrical junction box 10, the rear of the cross section is not generally shown.

[0031] In the circuit fixing step, the relays 40 and fuses 50, each having a bus bar 60 fixed thereto, are fixed to the upper case 30. The circuit fixing step may be performed after the film fixing step, before the film fixing step, or simultaneously with the film fixing step.

[0032] Next, after the film fixing step and the circuit fixing step, in the case assembling step, the lower case 20 and the upper case 30 are assembled together so that the bus bars 60 and the insulating film 70 come into contact with each other.

[0033] In the heat dissipation sheet fixing process, the heat dissipation sheet 80 is fixed to the underside of the insulating film 70. The heat dissipation sheet fixing process may be performed after the case assembling process or may be performed before the case assembling process. In this manner, the manufacture of the electrical junction box 10 is completed.

[0034] The advantages of the above embodiment are described below. (1) Because the bus bar 60 contacts the external cooling member 90 via the insulating film 70 and the heat dissipation sheet 80, good heat dissipation is ensured. This suppresses temperature increases in the relays 40 and the fuses 50. Furthermore, the insulating film 70 has a creepage distance-constituting portion 73 that constitutes part of the creepage distance between the bus bar 60 and the external cooling member 90 by being disposed on the bottom 21 of the lower case 20 from the edge 71 of the insulating film 70 to the opening end 23a of the through hole 23. This prevents the device from becoming too large while ensuring the creepage distance. That is, the insulating film 70 has the creepage distance-constituting portion 73 in the range H from the edge 71 to the opening end 23a of the through hole 23. This allows a longer creepage distance to be ensured compared to, for example, a configuration in which the insulating film 70 and the heat dissipation sheet 80 are simply interposed between the bus bar 60 and the external cooling member 90, in which the creepage distance is the same as the thickness of the insulating film 70 and the heat dissipation sheet 80. 4, in a case where the insulating film 70 is attached to the underside of the bus bar 60 while the bus bar 60 is exposed below the through hole 23, it becomes necessary to make the insulating film 70 protrude significantly from the bus bar 60 in order to ensure the creepage distance. This would result in, for example, a large, unnecessary space K being created inside the lower case 20 and the upper case 30, and the electrical junction box 10 becoming larger, but this can be prevented.

[0035] (2) Because the bus bar 60 is in contact with the insulating film 70 so as to be flush with the edge 71 of the insulating film 70, it is possible to minimize the creation of large, unnecessary spaces inside the lower case 20 and the upper case 30. In other words, compared to a configuration in which the insulating film 70 protrudes from the bus bar 60, it is possible to prevent the case from becoming large.

[0036] (3) The lower case 20 has a wall portion 22 that stands facing the edge portion 71 of the insulating film 70 so that the path including the creepage distance component 73 is the creepage distance between the bus bar 60 and the external cooling member 90. This eliminates the need for the lower case 20 to protrude significantly from the bus bar 60. This prevents the case from becoming too large.

[0037] (4) Fixing holes 24 are provided in the bottom 21 of the lower case 20 at positions between the relays 40 and the fuses 50, and the upper case 30 has fixing portions 33 that penetrate the fixing holes 24 and are fixed to the external cooling member 90. Therefore, the electrical junction box 10 can be stably fixed to the external cooling member 90 with a small number of fixing points. Furthermore, with this configuration, it is possible to prevent the creation of large, unnecessary spaces inside the lower case 20 and the upper case 30, even at positions between the relays 40 and the fuses 50, and therefore the electrical junction box 10 can be prevented from becoming larger.

[0038] (5) The insulating film 70 has a plurality of component-corresponding portions 72 corresponding to the relays 40 and the fuses 50, respectively. This reduces the number of components compared to a configuration in which the relays 40 and the fuses 50 are provided separately. This makes it easier to assemble the insulating film 70, for example.

[0039] (6) In the above method, the components can be easily assembled in desired positions while accommodating the relay 40, fuse 50, bus bar 60, and insulating film 70 inside the lower case 20 and the upper case 30. For example, compared to a method in which the lower case 20 is assembled to the upper case 30 with the relay 40, fuse 50, bus bar 60, and insulating film 70 fixed to the upper case 30, the insulating film 70 can be assembled in the desired position of the lower case 20 with high precision.

[0040] (Modifications) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0041] In the above embodiment, the bus bar 60 is in contact with the insulating film 70 so as to be flush with the edge 71 of the insulating film 70, but this is not limited to this. For example, the insulating film 70 may protrude from the bus bar 60.

[0042] In the above embodiment, the lower case 20 has a wall portion 22 that stands upright to face the edge portion 71 of the insulating film 70, but this is not limited to this, and the lower case 20 may be configured without a wall portion 22.

[0043] In the above embodiment, the fixing holes 24 are provided in the lower case 20 at positions between the relays 40 and the fuses 50, and the upper case 30 has the fixing portions 33 that pass through the fixing holes 24 and are fixed to the external cooling member 90. However, this is not limiting. In other words, the electrical junction box 10 may be fixed to the external cooling member 90 by other means.

[0044] In the above embodiment, the insulating film 70 has a plurality of component corresponding portions 72 corresponding to each of the relays 40 and the fuses 50, but this is not limited to this. For example, the insulating film 70 may be configured as a separate body for each of the relays 40 and the fuses 50.

[0045] In the above embodiment, the relay 40 and the fuse 50 are fixed to the upper case 30, but this is not limited to this. For example, the relay 40 and the fuse 50 may be fixed to the lower case 20 without going through the upper case 30.

[0046] In the above embodiment, the electrical junction box 10 includes the relay 40 and the fuse 50 as electrical circuit components, but the types of electrical circuit components may be changed, or the number of electrical circuit components may be changed. For example, in FIG. 1, the electrical junction box 10 is illustrated as including one relay 40 and one fuse 50, but the electrical junction box 10 may be configured to include a plurality of relays 40 and a plurality of fuses 50.

[0047] In the above embodiment, the manufacturing method of the electrical connection box 10 includes a film fixing process, a circuit fixing process, a case assembly process, and a heat dissipation sheet fixing process, but is not limited to this, and the electrical connection box 10 may be manufactured by other manufacturing methods.

[0048] The present disclosure encompasses the following aspects. Note that, for the purpose of facilitating understanding and not limitation, reference symbols indicating components of the embodiments are given in parentheses in the following description. (Supplementary Note 1) A heat dissipation device comprising: a lower case (20) having a bottom (21) with a through hole (23); an upper case (30) assembled to the lower case (20); electric circuit components (40; 50) housed inside the lower case (20) and the upper case (30); a bus bar (60) connected to the electric circuit components (40; 50); an insulating film (70) disposed on the bottom (21) so as to close the through hole (23), and having an upper surface in contact with the bus bar (60); and a heat dissipation sheet (80) in contact with the insulating film (70), provided to pass through the through hole (23), and in contact with an external cooling member (90), the insulating film (70) has a creepage distance forming portion (73) that forms part of the creepage distance between the bus bar (60) and the external cooling member (90) by being disposed on the bottom (21) from an edge portion (71) of the insulating film (70) to an opening end (23a) of the through hole (23), and the distance between the inner surface of the upper case (30) facing the edge portion (71) of the insulating film (70) and the edge portion (71) is shorter than the length (H) of the creepage distance forming portion (73) from the edge portion (71) to the opening end (23a).

[0049] According to this configuration, the creepage distance can be increased by providing the creepage distance forming portion, while the internal space of the electrical junction box can be minimized to reduce the size of the electrical junction box.

[0050] REFERENCE SIGNS LIST 10 Electrical junction box 20 Lower case 21 Bottom 22 Wall 23 Through hole 23a Open end 24 Fixing hole 30 Upper case 31 Side wall 32 Upper wall 33 Fixing portion 33a Screw hole 34 Screw 40 Relay (electrical circuit component) 41 Screw 50 Fuse (electrical circuit component) 60 Bus bar 70 Insulating film 71 Edge 72 Component corresponding portion 73 Creepage distance configuration portion 80 Heat dissipation sheet 90 External cooling member H Range K Space

Claims

1. An electrical junction box comprising: a lower case having a bottom with a through hole; an upper case assembled to the lower case; electric circuit components housed inside the lower case and the upper case; a bus bar connected to the electric circuit components; an insulating film arranged on the bottom so as to close the through hole and with an upper surface in contact with the bus bar; and a heat dissipation sheet arranged to pass through the through hole while in contact with the insulating film and in contact with an external cooling member, wherein the insulating film has a creepage distance forming portion that forms part of the creepage distance between the bus bar and the external cooling member by being arranged on the bottom from an edge of the insulating film to an open end of the through hole.

2. The electrical junction box according to claim 1, wherein the bus bar is in contact with the insulating film so as to be flush with an edge of the insulating film.

3. The electrical connection box according to claim 1, wherein the lower case has a wall portion erected to face the edge of the insulating film so that a path including the creepage distance forming portion becomes the creepage distance between the bus bar and the external cooling member.

4. An electrical junction box according to claim 1, comprising a plurality of the electric circuit components, wherein fixing holes are provided in the bottom portion at positions between the electric circuit components, and wherein the upper case has fixing portions that pass through the fixing holes and are fixed to the external cooling member.

5. The electrical connection box according to claim 1, comprising a plurality of said electric circuit components, and said insulating film having a plurality of component corresponding portions corresponding to each of said electric circuit components.

6. A method for manufacturing an electrical junction box as claimed in claim 1, comprising: a film fixing step of fixing the insulating film to the lower case; a circuit fixing step of fixing the electrical circuit components and the bus bar to the upper case; and a case assembling step of assembling the lower case and the upper case after the film fixing step and the circuit fixing step so that the bus bar and the insulating film come into contact with each other.

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