Bus bar fastening structure

Abstract

A bus bar fastening structure according to the present disclosure comprises: a mating member; a fastening member that is fastened to the mating member in a first direction; a fastening collar 70 that has a side surface extending in the first direction at a location excluding a fastened portion 73 fastened by the fastening member, is pressed against the mating member by the fastening member being fastened to the mating member, and is electrically connected to the mating member; and a bus bar 60 that is mechanically and electrically connected to the side surface. The fastening collar 70 has a strength higher than that of the bus bar 60, and a contact surface 77 of the fastened portion 73 that contacts the mating member is subjected to surface treatment.

Description

Busbar fastening structure

[0001] The present disclosure relates to a busbar fastening structure.

[0002] A fastening structure described in Japanese Patent Laid-Open No. 2023-82637 (hereinafter referred to as Patent Document 1) is known. The fastening structure described in Patent Document 1 includes a first fastened member containing pure aluminum or an aluminum alloy, a second fastened member containing a metal, and a fastening member that fastens the first fastened member and the second fastened member together. A protrusion containing pure aluminum or an aluminum alloy and protruding toward the second fastened member is integrally formed on the surface of the first fastened member facing the second fastened member. The pure aluminum or aluminum alloy on the protrusion of the first fastened member is in direct contact with the metal of the second fastened member.

[0003] JP 2023-82637 A

[0004] As in the fastening structure described above, pure aluminum is desirable from the viewpoints of electrical conductivity and weight reduction. However, pure aluminum has low strength, so there is a risk that the first fastened member (bus bar) will be deformed by the axial force applied during fastening. Furthermore, if the bus bar is made of aluminum, there is a risk that the fastening resistance will increase due to the oxide film.

[0005] The present disclosure was completed in light of the above circumstances, and aims to suppress deformation of a bus bar due to axial force during fastening while suppressing an increase in fastening resistance due to an oxide film.

[0006] The busbar fastening structure disclosed herein includes a mating member, a fastening member fastened to the mating member in a first direction, a fastening collar having a side extending in the first direction at a location excluding a fastened portion fastened by the fastening member, the fastening collar being pressed against the mating member when the fastening member is fastened to the mating member and being electrically connected to the mating member, and a busbar mechanically and electrically connected to the side surface, wherein the fastening collar has a strength greater than that of the busbar, and the contact surface of the fastened portion that comes into contact with the mating member is surface-treated.

[0007] According to the present disclosure, it is possible to suppress deformation of the bus bar due to the axial force during fastening, and to suppress an increase in fastening resistance due to an oxide film.

[0008] Fig. 1 is an exploded perspective view of an electrical junction box according to an embodiment. Fig. 2 is a plan view of the electrical junction box according to an embodiment. Fig. 3 is an enlarged front view of the vicinity of a relay according to an embodiment. Fig. 4 is a cross-sectional view taken along line A-A in Fig. 3. Fig. 5 is a diagram showing a state in which a rectangular fastening collar is fixed to a bus bar. Fig. 6 is a diagram showing a state in which a round fastening collar is fixed to a bus bar. Fig. 7 is a diagram showing a state in which a rectangular fastening collar is laser-welded to a bus bar. Fig. 8 is a diagram showing a state in which a round fastening collar is laser-welded to a bus bar.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] [1] The busbar fastening structure of the present disclosure comprises a mating member, a fastening member fastened to the mating member in a first direction, a fastening collar having a side extending in the first direction at a location excluding a fastened portion fastened by the fastening member, the fastening collar being pressed against the mating member when the fastening member is fastened to the mating member and being electrically connected to the mating member, and a busbar mechanically and electrically connected to the side surface, wherein the fastening collar has a strength greater than that of the busbar, and the fastened portion has a contact surface that comes into contact with the mating member, and the contact surface is surface-treated.

[0011] When the fastening member is fastened to the mating member, the fastening collar is pressed against the mating member, electrically connecting the bus bar and the mating member via the fastening collar. Although the fastening collar receives an axial force from the fastening member during fastening, the fastening collar has a higher strength than the bus bar, so deformation of the fastening collar due to the axial force during fastening can be suppressed. In addition, the fastening collar has a surface treatment applied to the contact surface that comes into contact with the mating member, which suppresses the formation of an oxide film on the contact surface and suppresses an increase in fastening resistance due to the oxide film.

[0012] [2] Preferably, the fastening collar has an angular outer shape, the bus bar has an angular fixing hole into which the fastening collar fits, and the outer surface of the fastening collar is connected to the inner surface of the fixing hole. The fastening collar is subjected to a rotational force when the fastening member is fastened, but because the fastening collar has an angular outer shape and fits into the fixing hole of the bus bar, rotation of the fastening collar can be prevented.

[0013] [3] Preferably, the fastening collar comprises a circular base having the fastened portion and a flange protruding from an outer periphery of the circular base in a second direction perpendicular to the first direction, and the side surface is formed on the outer periphery of the flange. Because the side surface of the fastening collar is formed on the outer periphery of the flange, it is possible to reliably prevent axial force during fastening from being applied to the connection portion between the fastening collar and the bus bar.

[0014] [Details of the Embodiments of the Present Disclosure] The following describes embodiments of the present disclosure. The present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the drawings, for the convenience of explanation, some components may be exaggerated or simplified. Furthermore, the dimensional ratios of each part may differ between drawings. In this specification, "orthogonal" does not only refer to a strict orthogonal relationship, but also includes a roughly orthogonal relationship within the scope of the operation and effect of this embodiment.

[0015] In addition, "facing" in this specification refers to surfaces or components facing each other, and includes not only cases where they are completely facing each other, but also cases where they are partially facing each other. In addition, "facing" in this specification includes both cases where a component separate from the two components is interposed between the two components, and cases where nothing is interposed between the two components.

[0016] 1 to 8, an embodiment of the present disclosure will be described. In the following description, the direction indicated by the arrow Z (an example of the second direction) is defined as upward, the direction indicated by the arrow X (an example of the second direction) as forward, and the direction indicated by the arrow Y (an example of the first direction) as leftward. Note that, for multiple identical components, only some of the components may be designated by reference numerals, and the reference numerals for the other components may be omitted.

[0017] (Electrical Junction Box JB) The electrical junction box JB of this embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle, and is disposed in a power supply path from a battery to a load such as a motor. As shown in FIG. 2 , the electrical junction box JB is connected to external bus bars 2 and 3. The external bus bars 2 and 3 are used to electrically connect the electrical junction box JB to devices (including a battery) provided outside the electrical junction box JB. The external bus bars 2 and 3 have portions disposed outside the electrical junction box JB. The external bus bar 2 is electrically connected to the battery. The external bus bar 3 is electrically connected to the load. The external bus bars 2 and 3 are connected to the electrical junction box JB by bolt fastening. As shown in FIG. 1 , the electrical junction box JB includes a case 10, a fuse 20, a relay (an example of a mating member) 30, a first bus bar 40, and a second bus bar 50.

[0018] (Case 10) The case 10 is made of synthetic resin and includes a lower case 11 and an upper case 12. The upper case 12 is assembled to and stacked on the lower case 11. When bolts B1, B3 are fastened from above to connect the external bus bars 2, 3 and the electrical junction box JB by bolt fastening, the upper case 12 is arranged above the lower case 11, as shown in Figures 1 and 2. Below, the configuration and arrangement of each component of the electrical junction box JB will be described assuming that the upper case 12 is arranged above the lower case 11.

[0019] As shown in Figure 1, the lower case 11 is formed in the shape of a tray that is long in the front-to-rear direction. The lower case 11 accommodates a fuse 20, a relay 30, a first bus bar 40, and a second bus bar 50. The fuse 20 is disposed in the front portion of the lower case 11. Bolts B1, B2 are fastened to terminal portions 22 formed on both the front and rear sides of the fuse 20, respectively. The relay 30 is disposed in the rear portion of the lower case 11. A bolt B3 is fastened to the rear end of the second bus bar 50.

[0020] (Upper Case 12) As shown in Fig. 1 , the upper case 12 is lid-shaped. The upper case 12 includes a first bus bar accommodating portion 12A that accommodates the first bus bar 40 and a second bus bar accommodating portion 12B that accommodates the second bus bar 50. Each bus bar accommodating portion 12A, 12B is provided in the shape of a groove that fits the shape of each bus bar 40, 50. A window portion 12C is provided at the front end of the upper case 12 for connecting the terminal portion 22 of the fuse 20 and the external bus bar 2.

[0021] (Fuse 20) The fuse 20 includes a main body 21 and two terminals 22 extending from both the front and rear ends of the main body 21. The main body 21 is block-shaped. The terminals 22 are made of metal. The terminals 22 are thin plates extending in the vertical direction. The terminals 22 are fastened to fixing nuts (not shown) of the lower case 11 with bolts B1 and B2.

[0022] (Relay 30) The relay 30 is a large mechanical relay through which a high current is passed from a battery. As shown in Figures 3 and 4, the relay 30 includes a main body 31 and a partition wall 32 extending from the right surface of the main body 31. The main body 31 is block-shaped. Two terminals 33 are formed on the right surface of the main body 31. The terminals 33 are disposed so as to protrude slightly to the right from the right surface of the main body 31, and the protruding end surfaces form a seat surface 35. A recess 34 is formed inside the terminal 33 and has a bottom that is open to the right and recessed to the left. A female thread is formed on the inner peripheral surface of the recess 34.

[0023] Bolts B4 and B5 (an example of a fastening member) can be fastened to each terminal 33. Male threads are formed on the outer circumferential surfaces of the shafts of the bolts B4 and B5. The male threads of the bolts B4 and B5 can enter recesses 34 of the terminals 33 and be screwed into the female threads. In this way, the bolts B4 and B5 are fastened to each terminal 33. The two terminals 33 of the relay 30 are arranged with the partition wall 32 between them.

[0024] (Busbar Fastening Structure) The first busbar 40 and the second busbar 50 are each formed by stamping and bending a conductive metal plate. As shown in Fig. 1 , the second busbar 50 includes a relay connection portion 51 connected to the terminal 33 of the relay 30 and an external connection portion 52 connected to the external busbar 3. The relay connection portion 51 has a bolt insertion hole H7 through which the bolt B4 is inserted. The external connection portion 52 has a bolt insertion hole through which the bolt B3 is inserted.

[0025] The first bus bar 40 includes a fuse connection portion 41 connected to the terminal portion 22 of the fuse 20, a relay connection portion (an example of a bus bar fastening structure) 42 connected to the terminal 33 of the relay 30, an intermediate portion 43 connecting the fuse connection portion 41 and the relay connection portion 42, and an extension portion 44 extending from the intermediate portion 43 forward of the fuse connection portion 41. The fuse connection portion 41 has a bolt insertion hole through which the bolt B2 is inserted. The relay connection portion 42 has a bolt insertion hole H7 through which the bolt B5 is inserted.

[0026] A bolt B2 is fastened to the fuse connection portion 41, and a bolt B5 is fastened to the relay connection portion 42. The fuse connection portion 41 extends leftward from the front end of the intermediate portion 43. The intermediate portion 43 is shaped like a plate extending in the front-to-rear direction. The extension portion 44 is disposed in the space to the right of the fuse 20, and functions to release heat transferred from the fuse 20 and relay 30 to the first bus bar 40 into the case 10.

[0027] 4 , the relay connection portion 42 includes a fastening collar 70 that is pressed against the seating surface 35 when the bolt B5 is fastened to the terminal 33, and a bus bar 60 that is electrically connected to the fastening collar 70 at a location other than a fastened portion 73 that is fastened by the bolt B5. In other words, the fastening collar 70 is pressed against the seating surface 35 when the fastened portion 73 is bolted to the terminal 33. This mechanically and electrically connects the fastening collar 70 to the terminal 33 of the relay 30. The same applies to the relay connection portion 51.

[0028] The fastening collar 70 includes a circular base 71 having a fastening portion 73 and a flange 72 protruding in the XZ plane direction from the outer periphery of the circular base 71. As shown in FIG. 7A , the circular base 71 has a thickness greater than that of the flange 72. A step 76 is formed between the circular base 71 and the flange 72. As shown in FIG. 3 , the circular base 71 has a circular outer shape, and the flange 72 has a rectangular outer shape. The fastening collar 70 has a higher strength than the bus bar 60. In this embodiment, the fastening collar 70 has a rectangular outer shape as shown in FIG. 5 , but a fastening collar 80 having a circular outer shape may also be used as shown in FIG. 6 .

[0029] 4, the bolt B5 has a bolt head B51 and a bolt shank B52. A bolt insertion hole H7, through which the bolt shank B52 is inserted, is formed in the center of the circular base 71 of the fastening collar 70, and the fastened portion 73 is formed around the bolt insertion hole H7.

[0030] The bus bar 60 is made of pure aluminum (such as 1000-series aluminum) from the viewpoints of electrical conductivity and weight reduction. On the other hand, the fastening collar 70 is made of a high-strength metal that is stronger than pure aluminum. The high-strength metal is a 6000-series aluminum alloy or copper, such as A6101, that has a strength sufficient to prevent buckling when fastened with a bolt. The fastening collar 70 of the present disclosure is made of a 6000-series aluminum alloy, but may also be made of copper.

[0031] The bus bar 60 has a rectangular collar fixing hole 61 into which the fastening collar 70 fits. An inner surface 62 of the collar fixing hole 61 and an outer surface 79 formed on the outer peripheral edge of the flange 72 are joined to each other. Both the outer surface 79 and the inner surface 62 are side surfaces that extend in the left-right direction (Y direction). This mechanically and electrically connects the bus bar 60 to the outer surface 79 of the fastening collar 70.

[0032] Examples of methods for joining a bus bar and a fastening collar and materials for the fastening collar used in such joining methods include the following: 1. Ultrasonic welding: copper material, aluminum material 2. Laser welding: aluminum material (nickel plating may be applied) 3. Electromagnetic pulse: copper material, aluminum material 4. Mechanical crimping: copper material, aluminum material

[0033] Ultrasonic welding allows for the joining of dissimilar materials, so copper can be selected as the material for the fastening collar, but aluminum can also be selected. Laser welding does not allow for the joining of dissimilar materials, so aluminum is used as the material for the fastening collar. Electromagnetic pulse welding allows for the joining of dissimilar materials, so copper can be selected as the material for the fastening collar, but aluminum can also be selected. Mechanical crimping is a crimping method that allows for the joining of dissimilar materials, so copper can be selected as the material for the fastening collar, but aluminum can also be selected.

[0034] In the fastening collar 70 of this embodiment, as shown in FIG. 7B , the outer surface 79 of the flange 72 is laser-welded to the inner surface 62 of the bus bar 60. As shown in FIG. 7A , the weld 74 is formed in a square ring shape. When laser welding is performed, a rib 75 may be formed on the surface of the weld 74. Because this rib 75 is lower than the height of the step 76 between the circular base 71 and the flange 72, interference of the rib 75 with a mating component, such as the relay 30, can be prevented during bolt fastening. Similarly, as shown in FIG. 8A , when a fastening collar 80 with a circular outer shape is used, an annular weld 84 is formed by laser welding, but interference of the rib 85 formed on the surface of the weld 84 with a mating component, such as the relay 30, can be prevented.

[0035] The fastening collar may be subjected to a surface treatment to reduce contact resistance. Examples of surface treatment include plating, anodizing, thermal spraying, and painting. Examples of plating include nickel plating and tin plating. This allows the material of the fastening collar to be selected without having to worry about contact resistance.

[0036] 7 and 8 , plating 78, 88 is formed on at least the contact surfaces 77, 87 of the fastening collars 70, 80 that come into contact with the seating surface 35. This prevents an oxide film from forming on the contact surfaces 77, 78. This prevents an increase in fastening resistance due to the oxide film. In this manner, the bus bar 60 is electrically connected to the relay 30 via the fastening collar 70 when the bolt B5 is fastened to the terminal 33 of the relay 30.

[0037] (Action and effect of the embodiment) The relay connection portion 42 according to the embodiment includes a relay 30, a bolt B5 fastened to the relay 30 in a first direction, an outer surface 79 extending in the first direction at a location excluding the fastened portion 73 fastened by the bolt B5, and a fastening collar 70 that is pressed against the relay 30 when the bolt B5 is fastened to the relay 30 and is electrically connected to the relay 30, and a bus bar 60 that is mechanically and electrically connected to the outer surface 79, the fastening collar 70 having a strength greater than that of the bus bar 60, and a contact surface 77 of the fastened portion 73 that comes into contact with the relay 30 is plated 78.

[0038] When the bolt B5 is fastened to the relay 30, the fastening collar 70 is pressed against the relay 30, and the bus bar 60 and the relay 30 are electrically connected via the fastening collar 70. Although the fastening collar 70 receives an axial force from the bolt B5 during fastening, the fastening collar 70 has a higher strength than the bus bar 60, so deformation of the fastening collar 70 due to the axial force during fastening can be suppressed. Furthermore, because the contact surface 77 of the fastening collar 70 that comes into contact with the relay 30 is plated with plating 78, formation of an oxide film on the contact surface 77 can be suppressed, thereby suppressing an increase in fastening resistance due to the oxide film.

[0039] It is preferable that the fastening collar 70 has an angular outer shape, the bus bar 60 has an angular collar fixing hole 61 into which the fastening collar 70 fits, and an outer surface 79 of the fastening collar 70 is connected to an inner surface 62 of the collar fixing hole 61. The fastening collar 70 is subjected to a rotational force when the bolt B5 is tightened, but because the outer shape of the fastening collar 70 is angular and the fastening collar 70 fits into the collar fixing hole 61 of the bus bar 60, rotation of the fastening collar 70 can be prevented.

[0040] The fastening collar 70 preferably includes a circular base 71 having a fastened portion 73 and a flange 72 protruding from the outer periphery of the circular base 71 in a second direction perpendicular to the first direction, and the outer surface 79 is formed on the outer periphery of the flange 72. Because the outer surface 79 of the fastening collar 70 is formed on the outer periphery of the flange 72, it is possible to reliably prevent an axial force from being applied to the connection portion between the fastening collar 70 and the bus bar 60 during fastening.

[0041] (Other Embodiments) The above-described embodiment can be modified and implemented as follows: The above-described embodiments can be implemented in combination with each other within the scope of technical compatibility.

[0042] In the above embodiment, the relay 30 is exemplified as the mating member. However, the mating member may be the fuse 20 or a bus bar.

[0043] In the above embodiment, the fastening collar 70 has the plating 78 formed only on the contact surface 77 that contacts the seat surface 35, but the fastening collar 70 may have the plating formed on the entire surface.

[0044] In the above embodiment, the fastening collar 70 has a rectangular outer shape, but the fastening collar may have a polygonal outer shape with three or five or more sides. Accordingly, the collar fixing hole may have a polygonal shape with three or five or more sides.

[0045] 2, 3: External connection bus bar 10: Case 11: Lower case 12: Upper case 12A: First bus bar accommodating portion 12B: Second bus bar accommodating portion 12C: Window portion 20: Fuse 21: Main body portion 22: Terminal portion 30: Relay (mating member) 31: Main body portion 32: Partition wall 33: Terminal 34: Recessed portion 35: Seat surface 40: First bus bar 41: Fuse connection portion 42: Relay connection portion 43: Middle portion 44: Extension portion 50: Second bus bar 51: Relay connection portion 52: External connection portion 60: Bus bar 61: Collar fixing hole (fixing hole) 62: Inner surface 70, 80: Fastening collar 71: Circular base 72: Flange 73: Fastened portion 74, 84: Welded portion 75, 85: Rib 76: Step 77, 87: Contact surface 78, 88: Plating (surface treatment) 79: Outer surface B1, B2, B3, B4, B5: Bolt B51: Bolt head B52: Bolt shaft H6, H7: Bolt insertion hole JB: Electrical junction box

Claims

1. A busbar fastening structure comprising: a mating member; a fastening member fastened to said mating member in a first direction; a fastening collar having a side extending in said first direction at a location excluding a fastened portion fastened by said fastening member, said fastening collar being pressed against said mating member when said fastening member is fastened to said mating member and being electrically connected to said mating member; and a busbar mechanically and electrically connected to said side, wherein said fastening collar has a strength greater than that of said busbar, and a surface treatment is applied to the contact surface of said fastened portion that comes into contact with said mating member.

2. The busbar fastening structure according to claim 1, wherein the fastening collar has an angular outer shape, the busbar has an angular fixing hole into which the fastening collar fits, and the outer surface of the fastening collar is connected to the inner surface of the fixing hole.

3. A busbar fastening structure as described in claim 1 or claim 2, wherein the fastening collar comprises a circular base having the fastened portion, and a flange protruding from the outer periphery of the circular base in a second direction perpendicular to the first direction, and the side surface is formed on the outer periphery of the flange.

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