Bus bar fastening structure

Abstract

To suppress a bus bar from deforming due to an axial force during fastening and suppress an increase in fastening resistance due to an oxide film.SOLUTION: A bus bar fastening structure according to the present disclosure includes: a mating member which has a seating surface 35; a fastening member; a bus bar 60 which is formed of high-strength aluminum that has higher strength than pure aluminum; and a fastening washer 70 which is mechanically and electrically connected to the bus bar 60 and is formed of a high-strength metal that has higher strength than pure aluminum. The fastening member is fastened to the mating member so that the fastening washer 70 is sandwiched between the bus bar 60 and the seating surface 35, and the bus bar 60 is electrically connected to the mating member via the fastening washer 70. A contact surface of the fastening washer 70, which is in contact with the seating surface 35, is subjected to surface treatment.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A fastening structure described in Japanese Patent Laid-Open No. 2023-82637 (Patent Document 1 below) is known. The fastening structure described in Patent Document 1 comprises 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-82637 Summary of the Invention [Problem to be solved by the invention]

[0004] As with the fastening structure described above, pure aluminum is desirable from the standpoints of 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. [Means for solving the problem]

[0006] The busbar fastening structure disclosed herein includes a mating member having a seating surface, a fastening member, a busbar formed from high-strength aluminum that is stronger than pure aluminum, and a fastening washer that is mechanically and electrically connected to the busbar and is formed from a high-strength metal that is stronger than pure aluminum, wherein when the fastening member is fastened to the mating member, the fastening washer is sandwiched between the busbar and the seating surface and the busbar is electrically connected to the mating member via the fastening washer, and a contact surface of the fastening washer that comes into contact with the seating surface is surface-treated. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an exploded perspective view of an electrical junction box according to an embodiment. [Figure 2] FIG. 2 is a plan view of the electrical junction box according to the embodiment. [Figure 3] FIG. 3 is an enlarged front view of the vicinity of the relay according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is a diagram showing a state in which a round fastening washer is welded to a bus bar. [Figure 6] FIG. 6 is a diagram showing a state in which a rectangular fastening washer is welded to a bus bar. [Figure 7] FIG. 7 is a diagram showing a state in which the fastening washer is laser-welded to the bus bar. [Figure 8] FIG. 8 is a diagram showing a state in which the fastening washer is ultrasonically welded to the bus bar. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] [1] The busbar fastening structure disclosed herein comprises a mating member having a seating surface, a fastening member, a busbar formed from high-strength aluminum having a strength greater than that of pure aluminum, and a fastening washer formed from a high-strength metal having a strength greater than that of pure aluminum and mechanically and electrically connected to the busbar, wherein the fastening member is fastened to the mating member so that the fastening washer is sandwiched between the busbar and the seating surface, and the busbar is electrically connected to the mating member via the fastening washer, and a surface treatment is applied to the contact surface of the fastening washer that comes into contact with the seating surface.

[0011] When the fastening member is fastened to the mating member, the fastening washer is sandwiched between the bus bar and the seating surface of the mating member, and the bus bar and the mating member are electrically connected via the fastening washer. Although the bus bar is subjected to an axial force from the fastening member during fastening, because the bus bar and the fastening washer are made of high-strength aluminum and high-strength metal, respectively, deformation of both the bus bar and the fastening washer due to the axial force during fastening can be suppressed. Furthermore, since the contact surface of the fastening washer that comes into contact with the seat surface is surface treated, the formation of an oxide film on the contact surface can be suppressed, and an increase in fastening resistance due to the oxide film can be suppressed.

[0012] [2] It is preferable that the fastening washer comprises a first connection portion connected to the mating member and a second connection portion connected to the bus bar, and that a portion of the second connection portion that protrudes more radially outward than the first connection portion is welded to the bus bar. The portion of the second connection portion that protrudes radially outward beyond the first connection portion can be mechanically and electrically connected to the bus bar by, for example, laser welding. Because a step corresponding to the height of the first connection portion is formed between the second connection portion and the mating member, even if a rib is formed by laser welding, the rib will not interfere with the mating member.

[0013] [3] It is preferable that the busbar connection surface of the fastening washer, which is connected to the busbar, is welded to the busbar over its entire surface. The busbar connection surface of the fastening washer, which is connected to the busbar, can be mechanically and electrically connected to the busbar by, for example, ultrasonic welding.

[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 sake of convenience, some components may be exaggerated or simplified. Furthermore, the dimensional ratios of the components 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 the present 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] <Embodiment> An embodiment of the present disclosure will be described with reference to Figures 1 to 8. In the following description, the direction indicated by arrow Z is defined as upward, the direction indicated by arrow X as forward, and the direction indicated by arrow Y 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 a battery. The external bus bar 3 is electrically connected to a 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 by being placed on top of the lower case 11. When connecting the external bus bars 2, 3 and the electrical junction box JB by bolting, if the bolts B1, B3 are fastened from above, the upper case 12 is arranged above the lower case 11, as shown in FIGS. 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 FIG. 1 , the lower case 11 is formed in the shape of a tray that is long in the front-to-rear direction. The fuse 20, the relay 30, the first bus bar 40, and the second bus bar 50 are arranged in the lower case 11. The fuse 20 is disposed in the front portion of the lower case 11. Bolts B1 and 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, upper case 12 is lid-shaped. Upper case 12 includes first busbar accommodating portion 12A that accommodates first busbar 40 and second busbar accommodating portion 12B that accommodates second busbar 50. Each busbar accommodating portion 12A, 12B is provided in the shape of a groove that fits the shape of each busbar 40, 50. A window portion 12C is provided at the front end of upper case 12 for connecting terminal portion 22 of fuse 20 and external busbar 2.

[0021] (Huse 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 flows from a battery. As shown in FIGS. 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 circumferential surface of the recess 34.

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

[0024] (Busbar fastening structure) The first bus bar 40 and the second bus bar 50 are each formed by stamping and bending a conductive metal plate. As shown in Fig. 1, the second bus bar 50 includes a relay connection portion 51 that connects to the terminal 33 of the relay 30, and an external connection portion 52 that connects to the external bus bar 3. The relay connection portion 51 has a bolt insertion hole 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 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 that extends in the front-to-rear direction. The extension portion 44 is arranged to utilize the space to the right of the fuse 20, and has the function of dissipating heat transferred from the fuse 20 and relay 30 to the first bus bar 40 to the case 10.

[0027] As shown in Fig. 4, relay connection unit 42 includes bus bar 60 having bolt insertion hole H6 and fastening washer 70 having bolt insertion hole H7. The same applies to relay connection unit 51. As shown in Fig. 5, fastening washer 70 of the present disclosure is mechanically and electrically connected to bus bar 60, but it may also be configured separately from bus bar 60, and mechanically and electrically connected to bus bar 60 by fastening bolts B4 and B5 to terminal 33.

[0028] The busbar 60 is made of high-strength aluminum, which is stronger than pure aluminum. High-strength aluminum is a 6000 series aluminum alloy, such as A6101, that is strong enough to prevent buckling when bolted. A6101 is a high-strength conductor alloy with good electrical conductivity. This prevents the busbar 60 from being deformed by the axial force when the bolt B5 is fastened.

[0029] The fastening washer 70 is formed of a high-strength metal that is stronger than pure aluminum. Examples of high-strength metals include 6000-series aluminum alloys and copper, such as A6101, that are strong enough to prevent bolt buckling. The fastening washer 70 of the present disclosure is formed of high-strength aluminum, but may also be formed of copper. The fastening washer 70 integrally includes a first connection portion 71 that connects to the relay 30 and a second connection portion 72 that connects to the bus bar 60. The first connection portion 71 and the second connection portion 72 both have a round outer shape and are arranged coaxially. The second connection portion 72 has a larger diameter than the first connection portion 71. The portion of the second connection portion 72 that protrudes radially outward beyond the first connection portion 71 serves as a joined portion 73 that is joined to the bus bar 60. In this embodiment, the fastening washer 70 has a round outer shape as shown in FIG. 5 . However, a fastening washer 80 having a rectangular outer shape may also be used as shown in FIG. 6 .

[0030] Examples of the method for joining the bus bar and the fastening washer and the material of the fastening washer used in the joining method include the following. 1. Ultrasonic welding: copper and aluminum materials 2. Laser welding: Aluminum material (nickel plating is acceptable) 3. Electromagnetic pulse: copper material, aluminum material 4. Mechanical crimping: copper and aluminum materials

[0031] Ultrasonic welding allows for the joining of dissimilar materials, so copper can be selected as the material for the fastening washer, 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 washer. Electromagnetic pulse welding allows for the joining of dissimilar materials, so copper can be selected as the material for the fastening washer, 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 washer, but aluminum can also be selected.

[0032] As shown in Fig. 7(A), in the fastening washer 70 of this embodiment, the to-be-joined portion 73 is laser-welded to the bus bar 60. The welded portion 74 is formed in an annular shape. When laser welding is performed, a rib 75 may be formed on the surface of the welded portion 74, as shown in Fig. 7(B). Because this rib 75 is lower than the height of the step 76 between the first connecting portion 71 and the second connecting portion 72, it is possible to prevent the rib 75 from interfering with a mating member such as the relay 30 when the bolt is fastened.

[0033] 8(A), a fastening washer 90 having a round outer shape may be used. This fastening washer 90 is formed in a plate shape and does not have the step 76 of the fastening washer 70, as shown in FIG. 8(B). A busbar connection surface 99 of such fastening washer 90, which is connected to the busbar 60, may be welded over its entire surface to the busbar 60 by ultrasonic welding or the like.

[0034] The fastening washer 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 washer to be selected without having to worry about contact resistance.

[0035] 7 and 8, plating 78, 98 is formed on at least the contact surfaces 77, 97 of the fastening washers 70, 90 that come into contact with the seat surface 35. This prevents an oxide film from forming on the contact surfaces 77, 97. This prevents an increase in fastening resistance due to the oxide film. In this way, the bus bar 60 is electrically connected to the relay 30 via the fastening washer 70 when the bolt B5 is fastened to the terminal 33 of the relay 30.

[0036] (Effects of the embodiment) The relay connection portion 42 according to the embodiment includes a relay 30 having a seat 35, a bolt B5, a bus bar 60 formed from high-strength aluminum having a strength greater than that of pure aluminum, and a fastening washer 70 formed from a high-strength metal having a strength greater than that of pure aluminum and mechanically and electrically connected to the bus bar 60, wherein the fastening washer 70 is sandwiched between the bus bar 60 and the seat 35 when the bolt B5 is fastened to the relay 30, and the bus bar 60 is electrically connected to the relay 30 via the fastening washer 70, and a contact surface 77 of the fastening washer 70 that comes into contact with the seat 35 is plated with plating 78.

[0037] When bolt B5 is fastened to relay 30, fastening washer 70 is sandwiched between busbar 60 and seat surface 35 of relay 30, and busbar 60 and relay 30 are electrically connected via fastening washer 70. Although busbar 60 receives axial force from bolt B5 during fastening, because busbar 60 and fastening washer 70 are made of high-strength aluminum and high-strength metal, respectively, deformation of both busbar 60 and fastening washer 70 due to the axial force during fastening can be suppressed. Furthermore, since plating 78 is formed on contact surface 77 of fastening washer 70 that comes into contact with seat surface 35, formation of an oxide film on contact surface 77 can be suppressed, thereby suppressing an increase in fastening resistance due to the oxide film.

[0038] The fastening washer 70 has a first connection portion 71 connected to the relay 30 and a second connection portion 72 connected to the bus bar 60, and it is preferable that the joined portion 73 of the second connection portion 72, which protrudes more radially outward than the first connection portion 71, is welded to the bus bar 60. Of the second connection portion 72, the joined portion 73 that protrudes more radially outward than the first connection portion 71 can be mechanically and electrically connected to the bus bar 60 by, for example, laser welding. Since a step 76 corresponding to the height of the first connection portion 71 is formed between the second connection portion 72 and the relay 30, even if a rib 75 is formed by laser welding, the rib 75 will not interfere with the relay 30.

[0039] It is preferable that the entire surface of a bus bar connecting surface 91 of fastening washer 90 that is connected to bus bar 60 is welded to bus bar 60 . A busbar connection surface 91 of the fastening washer 90 that is connected to the busbar 60 can be mechanically and electrically connected to the busbar 60 by, for example, ultrasonic welding.

[0040] (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. In the above embodiment, the relay 30 is exemplified as the mating member, but the mating member may be the fuse 20 or a bus bar.

[0041] In the above embodiment, the fastening washer 70 has the plating 78 formed only on the contact surface 77 that comes into contact with the seat surface 35, but the fastening washer 70 may have the plating formed on the entire surface. [Explanation of symbols]

[0042] 2,3: External connection busbar 10: Case 11: Lower case 12: Upper case 12A: First bus bar housing 12B: Second bus bar housing 12C: Window section 20: Fuse 21: Main body 22:Terminal section 30: Relay (mating component) 31: Main body 32: Partition wall 33: Terminal 34: Recess 35: Seat 40: First bus bar 41: Fuse connection 42: Relay connection part (busbar fastening structure) 43: Middle part 44: Extension part 50: Second bus bar 51: Relay connection 52: External connection part 60: Busbar 70, 80, 90: Fastening washer 71: First connection part 72: Second connection part 73: Part to be joined 74: Welded section 75: Rib 76: Step 77,97: Contact surface 78,98: Plating (surface treatment) 79: Bolt insertion hole 99: Busbar connection surface B1, B2, B3, B4, B5: Bolts H6, H7: Bolt insertion holes JB: Electrical junction box

Claims

1. a mating member having a seating surface; A fastening member; a bus bar formed from high-strength aluminum that is stronger than pure aluminum; a fastening washer that is mechanically and electrically connected to the bus bar and is made of a high-strength metal that is stronger than pure aluminum; When the fastening member is fastened to the mating member, the fastening washer is sandwiched between the bus bar and the seat surface, and the bus bar is electrically connected to the mating member via the fastening washer, A busbar fastening structure in which a contact surface of the fastening washer that comes into contact with the seat surface is surface-treated.

2. the fastening washer includes a first connection portion connected to the mating member and a second connection portion connected to the bus bar, The busbar fastening structure according to claim 1 , wherein a portion of the second connection portion that protrudes more radially outward than the first connection portion is welded to the busbar.

3. The bus bar fastening structure according to claim 1 , wherein a bus bar connecting surface of the fastening washer that is connected to the bus bar is welded to the bus bar over the entire surface thereof.

Images