Bus bar fastening structure and electric connection box

Abstract

A bus bar fastening structure according to the present disclosure comprises: an electronic component that has a terminal 33 and generates heat via electrification; a fastening member; a fastening bus bar 60 that is electrically connected to the electronic component by being fastened to the terminal 33 by the fastening member; and a connection bus bar 70 that is electrically connected to a portion of the fastening bus bar 60 excluding a fastened portion 61 that is fastened by the fastening member. The fastening bus bar 60 is of greater strength than that of the connection bus bar 70.

Description

Busbar fastening structure and electrical connection box

[0001] The present disclosure relates to a busbar fastening structure and an electrical junction box.

[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 above-described fastening structure, pure aluminum is preferably used from the viewpoints of electrical conductivity and weight reduction. However, pure aluminum has low strength, and there is a risk that the first fastened member (bus bar) may be deformed by the axial force applied during fastening.

[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.

[0006] The busbar fastening structure of the present disclosure is a busbar fastening structure comprising: an electronic component having a terminal and generating heat when current is passed through it; a fastening member; a fastening busbar that is fastened to the terminal by the fastening member and thereby electrically connected to the electronic component; and a connecting busbar that is electrically connected to portions of the fastening busbar excluding fastened portions that are fastened by the fastening member, wherein the fastening busbar has greater strength than the connecting busbar.

[0007] According to the present disclosure, it is possible to suppress deformation of the bus bar due to the axial force at the time of fastening.

[0008] FIG. 1 is an exploded perspective view of an electrical junction box according to a first embodiment. FIG. 2 is a plan view of the electrical junction box according to the first embodiment. FIG. 3 is an enlarged front view of the vicinity of a relay according to the first embodiment. FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3. FIG. 5 is an enlarged front view of the vicinity of a relay according to a second embodiment. FIG. 6 is a cross-sectional view taken along line B-B in FIG. 5. FIG. 7 is an enlarged front view of the vicinity of a relay according to a third embodiment. FIG. 8 is a cross-sectional view taken along line C-C in FIG. 7. FIG. 9 is an enlarged front view of the vicinity of a relay according to a fourth embodiment. FIG. 10 is a cross-sectional view taken along line D-D in FIG. 9. FIG. 11 is an enlarged front view of the vicinity of a relay according to a first example. FIG. 12 is an enlarged front view of the vicinity of a relay according to a second example. FIG. 13 is an enlarged front view of the vicinity of a relay according to a third example. FIG. 14 is an enlarged front view of the vicinity of a relay according to a fourth example. FIG. 15 is an enlarged front view of the vicinity of a relay according to a fifth example. FIG. 16 is an enlarged front view of the vicinity of a relay according to a sixth example. FIG. 17 is an enlarged front view of the vicinity of a relay according to a seventh example. FIG. 18 is an enlarged front view of the vicinity of a relay according to an eighth example. Fig. 19 is an enlarged front view of the vicinity of the relay according to Example 9. Fig. 20 is a perspective view showing the internal structure of the electrical junction box according to Embodiment 5. Fig. 21 is an exploded perspective view of the electrical junction box according to Embodiment 5. Fig. 22 is a cross-sectional view of the vicinity of the fuse in Fig. 21. Fig. 23 is a cross-sectional view of the vicinity of the fuse according to Example 10. Fig. 24 is a cross-sectional view of the vicinity of the fuse according to Example 11. Fig. 25 is a cross-sectional view of the vicinity of the fuse according to Example 12. Fig. 26 is a cross-sectional view of the vicinity of the fuse according to Example 13. Fig. 27 is a cross-sectional view of the vicinity of the fuse according to Example 14.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. [1] A bus bar fastening structure of the present disclosure includes an electronic component having a terminal and generating heat when energized, a fastening member, a fastening bus bar that is fastened to the terminal by the fastening member to be electrically connected to the electronic component, and a connecting bus bar that is electrically connected to a portion of the fastening bus bar excluding a fastened portion that is fastened by the fastening member, wherein the fastening bus bar has a higher strength than the connecting bus bar.

[0010] The fastening bus bar is fastened to the terminal of the electronic component with the fastening member, thereby electrically connecting the fastening bus bar and the electronic component. Although the fastening bus bar receives an axial force from the fastening member during fastening, the fastening bus bar has a higher strength than the connecting bus bar, and therefore deformation of the fastening bus bar due to the axial force during fastening can be suppressed.

[0011] Furthermore, because the connecting busbar is electrically connected to the fastening busbar at locations other than the fastened portions that are fastened by the fastening members, even if the fastening busbar deforms slightly, deformation of the connecting busbar can be suppressed. This allows the connecting busbar to be made of, for example, pure aluminum, thereby reducing the weight of the busbar fastening structure.

[0012] [2] In the above [1], it is preferable that the fastening member has a bolt head, and the connecting bus bar has a bolt relief hole for allowing the bolt head to escape, and a joined portion formed around the bolt relief hole and joined to the fastening bus bar. Since the joined portion is formed around the bolt relief hole, deformation of the joined portion can be suppressed.

[0013] [3] In the above [1] or [2], it is preferable that the fastening busbar has a heat sink portion formed in a non-current-carrying area different from a current-carrying area that conducts current between the fastening busbar and the connecting busbar. Because the fastening busbar has a heat sink portion formed in the non-current-carrying area, the heat sink portion can increase heat capacity without affecting conductivity, and heat generated in the electronic component can be released to the heat sink portion.

[0014] [4] In any one of the above [1] to [3], the heat-drawing portion is preferably formed in a folded shape. Because the heat-drawing portion is formed in a folded shape, the busbar fastening structure can be made smaller than when the heat-drawing portion is formed in a straight line.

[0015] [5] In any one of the above [1] to [4], it is preferable to further include a heat-dissipating bus bar that is fastened together with the fastening bus bar. The heat-dissipating bus bar can increase thermal capacity, allowing heat generated by the electronic components to be released to the heat-dissipating bus bar.

[0016] [6] In any of the above [1] to [5], it is preferable that the fastening busbar is subjected to a surface treatment. For example, surface treatment such as plating can prevent an oxide film from being formed on the surface of the fastening busbar, thereby reducing the contact resistance between the fastening busbar and the connecting busbar.

[0017] [7] In any one of the above [1] to [6], it is preferable that at least one of the fastening bus bar and the connecting bus bar is thermally connected to a cooling surface, so that at least one of the fastening bus bar and the connecting bus bar can be cooled by the cooling surface.

[0018] [8] In any one of the above [1] to [7], the thermal conductivity and electrical conductivity of the connection bus bar are preferably higher than those of the fastening bus bar. The connection bus bar can ensure heat dissipation and electrical conductivity.

[0019] [9] In any of the above [1] to [8], it is preferable that the joint between the connection bus bar and the fastening bus bar is at least on the conductive path direction side when viewed from the fastening direction of the fastening member. Because the joint position is at least on the conductive path direction side, good conductivity can be ensured.

[0020]

[10] In any one of the above [1] to [9], it is preferable that the joint positions between the connection bus bar and the fastening bus bar are arranged along at least two sides of the periphery of the fastening member, thereby ensuring sufficient joint strength between the connection bus bar and the fastening bus bar.

[0021]

[11] The electrical connection box of the present disclosure may include the bus bar fastening structure described in any one of [1] to

[10] above, and another electronic component that is electrically connected to the electronic component via the fastening bus bar and the connecting bus bar.

[0022] [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.

[0023] 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.

[0024] First Embodiment A first embodiment of the present disclosure will be described with reference to Figures 1 to 4. 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.

[0025] (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 (an example of another electronic component), a relay 30 (an example of an electronic component), a first bus bar 40, and a second bus bar 50.

[0026] (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 to 3. 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.

[0027] (Lower Case 11) 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.

[0028] (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.

[0029] (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.

[0030] (Relay 30) The relay 30 is a large mechanical relay through which a high current is passed 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. A recess 34 is formed inside the terminal 33, and is bottomed and recessed to the left while opening to the right. A female thread is formed on the inner circumferential surface of the recess 34. A male thread is formed on the outer circumferential surface of the shaft B52 of the bolts B4 and B5. The male threads of the bolts B4 and B5 can enter the recess 34 of the terminal 33 and be threaded into the female thread. As a result, the bolts B4 and B5 are fastened to each terminal 33, respectively. The two terminals 33 of the relay 30 are arranged on either side of a partition wall 32 .

[0031] (Busbar Fastening Structure) The first busbar 40 and the second busbar 50 are each formed by stamping and bending a conductive metal plate. 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 an insertion hole through which the bolt B4 is inserted. The external connection portion 52 has an insertion hole through which the bolt B3 is inserted.

[0032] 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 42 (an example of a bus bar fastening structure) 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 an insertion hole through which a bolt B2 is inserted. The relay connection portion 42 has an insertion hole through which a bolt B5 (an example of a fastening member) is inserted.

[0033] 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.

[0034] 4 , the relay connection portion 42 includes a fastening bus bar 60 that is fastened to the terminal 33 with a bolt B5 to be electrically connected to the relay 30, and a connection bus bar 70 that is electrically connected to a bus bar joining region 62 of the fastening bus bar 60 excluding a fastened portion 61 that is fastened by the bolt B5. A joint 45 is formed between the bus bar joining region 62 and the connection bus bar 70. The fastening bus bar 60 has a higher strength than the connection bus bar 70.

[0035] The bolt B5 has a bolt head B51. The connection bus bar 70 has a bolt relief hole 71 that allows the bolt head B51 to escape, and a joined portion 72 that is formed around the bolt relief hole 71 and is joined to the fastening bus bar 60. The joined portion 72 is thermally connected to a heat dissipation member H. For example, the heat dissipation member H may be in contact with the surface of the joined portion 72 opposite to the fastening bus bar 60. The heat dissipation member H corresponds to the "cooling surface" of the present disclosure and is, for example, the case 10 of the electrical junction box JB or the housing of a battery pack.

[0036] It is preferable to use a bus bar with sufficient strength (for example, high-strength aluminum such as 6000-series aluminum alloy, copper, etc.) as the fastening bus bar 60. This can prevent the fastening bus bar 60 from being deformed by the axial force when the bolt B5 is fastened. On the other hand, it is preferable to use pure aluminum (1000-series aluminum, etc.) as the connecting bus bar 70 from the viewpoints of electrical conductivity and weight reduction. The fastening bus bar 60 and the connecting bus bar 70 are mechanically and electrically connected. It is preferable that the thermal conductivity and electrical conductivity of the connecting bus bar 60 be higher than those of the fastening bus bar 70. This can increase the heat capacity in the vicinity of the relay 30.

[0037] The fastening bus bar 60 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. In this way, the material of the fastening bus bar 60 can be selected without having to worry about contact resistance.

[0038] Examples of joining methods for the joints 45 and materials for the fastening bus bars 60 used in those joining methods include the following: 1. Ultrasonic welding: copper material, aluminum material 2. Laser welding: aluminum material (which may be nickel-plated) 3. Electromagnetic pulse: copper material 4. Mechanical crimping: copper material, aluminum material

[0039] Ultrasonic welding allows for joining of dissimilar materials, so copper can be selected as the material for the fastening bus bar 60, but aluminum can also be selected. Laser welding does not allow for joining of dissimilar materials, so aluminum is used as the material for the fastening bus bar 60. Electromagnetic pulse welding allows for joining of dissimilar materials, so copper can be selected as the material for the fastening bus bar 60, but aluminum can also be selected. Mechanical crimping allows for joining of dissimilar materials, so long as the crimping method allows for joining of dissimilar materials, so copper can be selected as the material for the fastening bus bar 60, but aluminum can also be selected.

[0040] The joint 45 is formed by joining the jointed portion 72 formed around the bolt relief hole 71 to the fastening bus bar 60, so that fastening buckling of the connecting bus bar 70 can be avoided while the fastening bus bar 60 can increase heat capacity. Furthermore, because the joint 45 can be ensured to be wide, the joint strength between the fastening bus bar 60 and the connecting bus bar 70 can be increased. Furthermore, because the joint 45 is located at least on the side of the conductive path direction when viewed from the fastening direction, good conductivity can be ensured.

[0041] (Effects of First Embodiment) The relay connection portion 42 according to the first embodiment includes a relay 30 having a terminal 33 and generating heat when current is applied, a bolt B5, a fastening bus bar 60 fastened to the terminal 33 by the bolt B5 to be electrically connected to the relay 30, and a connection bus bar 70 electrically connected to a bus bar joining region 62 of the fastening bus bar 60 excluding a fastened portion 61 fastened by the bolt B5, the fastening bus bar 60 having a strength higher than that of the connection bus bar 70. The relay 30 is electrically connected to the fuse 20 via the fastening bus bar 60 and the connection bus bar 70.

[0042] Fastening the fastening bus bar 60 to the terminal 33 of the relay 30 with the bolt B5 electrically connects the fastening bus bar 60 and the relay 30. Although the fastening bus bar 60 receives an axial force from the bolt B5 during fastening, the fastening bus bar 60 has a strength higher than that of the connection bus bar 70, and therefore deformation of the fastening bus bar 60 due to the axial force during fastening can be suppressed.

[0043] Furthermore, since the connection bus bar 70 is electrically connected to the bus bar joining region 62 of the fastening bus bar 60, excluding the fastened portion 61 fastened by the bolt B5, even if the fastening bus bar 60 is slightly deformed, this can prevent deformation of the connection bus bar 70. This allows pure aluminum to be used as the material for the connection bus bar 70, thereby reducing the weight of the relay connection portion 42 and, ultimately, the electrical junction box JB.

[0044] The bolt B5 has a bolt head B51, and the connecting bus bar 70 preferably has a bolt relief hole 71 that allows the bolt head B51 to escape, and a joined portion 72 that is formed around the bolt relief hole 71 and is joined to the fastening bus bar 60. Because the joined portion 72 is formed around the bolt relief hole 71, deformation of the joined portion 72 can be suppressed.

[0045] It is preferable that a surface treatment is applied to the fastening bus bar 60. For example, surface treatment such as plating can prevent an oxide film from being formed on the surface of the fastening bus bar 60, thereby reducing the contact resistance between the fastening bus bar 60 and the connecting bus bar 70.

[0046] Second Embodiment A second embodiment of the present disclosure will be described with reference to Figures 5 and 6. An electrical junction box JB2 according to the second embodiment is configured substantially similarly to the first embodiment except for the configuration of the bus bar fastening structure (relay connection portions 42, 51) of the first embodiment, and therefore, descriptions of the same components, functions, and effects as those of the first embodiment may be omitted.

[0047] The electrical junction box JB2 includes relay connection portions 422 and 512. The relay connection portions 422 and 512 include a fastening bus bar 602 and a connection bus bar 70. A joint portion 45 is formed between the bus bar joint region 62 of the fastening bus bar 602 and the connection bus bar 70. The fastening bus bar 602 has a higher strength than the connection bus bar 70.

[0048] The fastening busbar 602 has a heat-removing portion H2 formed in a non-conductive region R2 different from the conductive region R1. The heat-removing portion H2 extends upward from the busbar joint region 62. The conductive region R1 mainly corresponds to the combined region where the joint 45 is formed and the region extending to the right (in the direction of the conductive path) from this region. The non-conductive region R2 corresponds to the region extending upward (in a direction different from the direction of the conductive path) from the region where the joint 45 is formed.

[0049] According to this embodiment, heat capacity can be increased by the heat sink portion H2 of the fastening bus bar 602. In particular, since the heat sink portion H2 is formed in the non-current-carrying region R2, heat capacity can be increased by the heat sink portion H2 without affecting conductivity, and heat generated in the relay 30 can be released to the heat sink portion H2. Furthermore, since the joint portion 45 is at least on the side of the conductive path direction when viewed from the fastening direction, good conductivity can be ensured.

[0050] Third Embodiment A third embodiment of the present disclosure will be described with reference to Figures 7 and 8. The electrical junction box JB3 according to the third embodiment is configured substantially similarly to the first embodiment except for the configuration of the bus bar fastening structure (relay connection portions 42, 51) of the first embodiment, and therefore, descriptions of the same components, functions, and effects as those of the first embodiment may be omitted.

[0051] The electrical junction box JB3 includes relay connection portions 423 and 513. The relay connection portions 423 and 513 include a fastening bus bar 60, a connection bus bar 703, and a heat-dissipating bus bar 80. A joint portion 453 is formed between the bus bar joint region 62 of the fastening bus bar 60 and the connection bus bar 703. The fastening bus bar 60 has a higher strength than the connection bus bar 703. The material of the heat-dissipating bus bar 80 can be selected from inexpensive materials (for example, iron, copper, strong aluminum, etc.).

[0052] The connecting bus bar 703 is formed shorter in the left-right direction than the connecting bus bar 70 in the first embodiment. The edge of the connecting bus bar 703 is offset in the left-right direction so as not to overlap with the bolt B53. In this embodiment, the connecting bus bar 703 does not have bolt relief holes for accommodating the bolt heads, and the heat-dissipating bus bar 80 is fastened together with the fastening bus bar 60. This configuration allows the heat-dissipating bus bar 80 to increase thermal capacity, allowing heat generated in the relay 30 to be dissipated to the heat-dissipating bus bar 80. Furthermore, since the joint 453 is located at least on the side of the conductive path direction when viewed from the fastening direction, good conductivity can be ensured.

[0053] Fourth Embodiment A fourth embodiment of the present disclosure will be described with reference to Figures 9 and 10. An electrical junction box JB4 according to the fourth embodiment is configured substantially similarly to the first embodiment except for the configuration of the bus bar fastening structure (relay connection portions 42, 51) of the first embodiment, and therefore, descriptions of the same components, functions, and effects as those of the first embodiment may be omitted.

[0054] The electrical junction box JB4 includes relay connection portions 424 and 514. The relay connection portions 424 and 514 include a fastening bus bar 604 and a connection bus bar 70. A joint portion 45 is formed between the bus bar joint region 62 of the fastening bus bar 604 and the connection bus bar 70. The fastening bus bar 604 has a higher strength than the connection bus bar 70.

[0055] The fastening busbar 604 has a heat-removing portion H4 formed in a non-conductive region R4 different from the conductive region R1. The heat-removing portion H4 extends upward from the busbar joint region 62. The conductive region R1 mainly corresponds to the combined region of the region where the joint 45 is formed and the region extending to the right (in the direction of the conductive path) from this region. The non-conductive region R4 corresponds to the region that extends upward (in a direction different from the direction of the conductive path) from the region where the joint 45 is formed and then folded back downward.

[0056] According to this embodiment, the heat sink portion H4 of the fastening bus bar 604 can provide sufficient heat capacity. In particular, the heat sink portion H4 is formed by extending upward and then folding back downward, which allows the electrical junction box JB4 to be more compact in the vertical direction than if the heat sink portion were formed linearly. The heat sink portion H4 provides sufficient heat capacity, allowing heat generated in the relay 30 to be released to the heat sink portion H4. Furthermore, as viewed from the fastening direction, the joint portion 45 is located at least on the side of the conductive path, ensuring good conductivity.

[0057] Examples 1 to 9 of the present disclosure will be described with reference to Fig. 11 to Fig. 19. The electrical junction boxes JB according to Examples 1 to 9 are configured in substantially the same manner as in Embodiment 1, except that they are more specific implementations of the joining method of Embodiment 1. Therefore, descriptions of the same components, functions, and effects as in Embodiment 1 may be omitted.

[0058] In Example 1 shown in Fig. 11, the connection bus bar 70 is joined to the fastening bus bar 60 by laser welding. The laser welding is performed in an annular shape so as to surround the fastening portions of the bolts B4 and B5. For example, the laser welding may be performed multiple times so that the rectangular and gate-shaped weld lines do not overlap each other. The joining position is indicated by the symbol JP1.

[0059] In Example 2 shown in Figure 12, the connection bus bar 70 is joined to the fastening bus bar 60 by laser welding. The laser welding is performed on both the top and bottom of the fastening portion of the bolts B4 and B5. For example, the laser welding may be performed in a form in which the weld line is linear and extends in the left-right direction, and in which multiple welds are lined up in the up-down direction. The joining position is indicated by the symbol JP2.

[0060] In Example 3 shown in FIG. 13 , the connection bus bar 70 is joined to the fastening bus bar 60 by laser welding. The laser welding is performed in an L-shape on the lower and right sides of the fastening portion of bolt B4, and in a linear manner on the lower side of the fastening portion of bolt B5. Laser welding may be performed, for example, along two sides, the upper and right sides, of the fastening bus bar 60, to increase the joint area. Laser welding may also be performed, for example, in a form in which the weld line is linearly extending in the left-right direction between the lower side of the fastening bus bar 60 and bolt B5, with multiple welds arranged vertically, to increase the joint area. The joint position is indicated by the symbol JP3. According to Example 3, the joint position JP3 is located along at least two sides around bolt B4, thereby ensuring sufficient joint strength between the connection bus bar 70 and the fastening bus bar 60.

[0061] In Example 4 shown in Fig. 14, the connection bus bar 70 is joined to the fastening bus bar 60 by laser welding. The laser welding is performed on both the top and bottom of the fastening portion of the bolts B4 and B5. For example, the laser welding may be performed with a circular weld line and multiple welds lined up in the left-right direction. The joining position is indicated by the symbol JP4.

[0062] In Example 5 shown in FIG. 15 , the connection bus bar 70 is joined to the fastening bus bar 60 by laser welding. The laser welding is performed in an L-shape on the lower and right sides of the fastening portion of bolt B4, and in a line on the lower side of the fastening portion of bolt B5. For example, the laser welding may be performed in an annular shape along two sides, the upper and right sides, of the fastening bus bar 60, to increase the joining area. Furthermore, the laser welding may be performed in an annular shape with multiple weld lines arranged in the left-right and up-down directions between the lower side of the fastening bus bar 60 and bolt B5, to increase the joining area. The joining position is indicated by the symbol JP5. According to Example 5, the joining position JP5 is located along at least two sides around bolt B4, thereby ensuring sufficient joining strength between the connection bus bar 70 and the fastening bus bar 60.

[0063] In Example 6 shown in Fig. 16, the connection bus bar 70 is joined to the fastening bus bar 60 by ultrasonic welding. The ultrasonic welding is performed on both the top and bottom of the fastening portion of the bolts B4 and B5. For example, the ultrasonic welding may be performed so that the welded portion has a rectangular shape that is long in the left-right direction. The joining position is indicated by the symbol JP6.

[0064] In Example 7 shown in FIG. 17 , the connection bus bar 70 is joined to the fastening bus bar 60 by ultrasonic welding. Ultrasonic welding is performed in an L-shape on the lower and right sides of the fastening portion of bolt B4, and on the lower side of the fastening portion of bolt B5. Ultrasonic welding may be performed, for example, along two sides, the upper and right sides, of the fastening bus bar 60, to increase the joining area. Alternatively, ultrasonic welding may be performed, for example, between the lower side of the fastening bus bar 60 and bolt B5, to increase the joining area by forming a rectangular weld that is long in the left-right direction. The joining position is indicated by the symbol JP7. According to Example 7, the joining position JP7 is located along at least two sides around bolt B4, thereby ensuring sufficient joining strength between the connection bus bar 70 and the fastening bus bar 60.

[0065] In Example 8 shown in Fig. 18, the connection bus bar 70 is joined to the fastening bus bar 60 by mechanical crimping. The mechanical crimping is performed at two corners that sandwich the fastening portions of the bolts B4 and B5. For example, the mechanical crimping may be performed at the upper right and lower left corners of the fastening bus bar 60 so that the crimped portions are rectangular and long in the left-right direction. Alternatively, the mechanical crimping may be performed at the upper left and lower right corners of the fastening bus bar 60 so that the crimped portions are rectangular and long in the left-right direction. The joining position is indicated by the symbol JP8.

[0066] In Example 9 shown in FIG. 19 , the connection bus bar 70 is joined to the fastening bus bar 60 by mechanical crimping. The mechanical crimping is performed below the fastening portions of the bolts B4 and B5. For example, the mechanical crimping may be performed at the lower right and lower left corners of the fastening bus bar 60 so that the crimped portions are substantially square. Alternatively, the mechanical crimping may be performed in a rectangular shape that is long in the left-right direction between the lower edge of the fastening bus bar 60 and the bolt B5, thereby increasing the joining area at one point. The joining position is indicated by the symbol JP9.

[0067] Fifth Embodiment A fifth embodiment of the present disclosure will be described with reference to Figures 20 to 22. An electrical junction box JB5 according to the fifth embodiment is configured substantially similarly to the first embodiment except for the configuration of the fastening structure of the lower case 11 and the first bus bar 40 of the first embodiment, and therefore, descriptions of the same components, functions, and effects as those of the first embodiment may be omitted.

[0068] (Electrical junction box JB5) The electrical junction box JB5 of this embodiment includes a case 105, a fuse 20 (an example of an electronic component), a relay 30 (an example of another electronic component), a first bus bar 405, and a second bus bar 50.

[0069] (Case 105) The case 105 is made of synthetic resin and includes a lower case 115 and an upper case 12. The upper case 12 is assembled to be stacked on the lower case 115. When the bolts B1, B3 are fastened from above to connect the external bus bars 2, 3 and the electrical junction box JB5 by bolt fastening, the upper case 12 is arranged above the lower case 115. Below, the configuration and arrangement of the electrical junction box JB5 will be described assuming that the upper case 12 is arranged above the lower case 115.

[0070] (Lower Case 115) As shown in Figures 20 and 21 , the lower case 115 is formed in the shape of a tray that is long in the front-to-rear direction. The fuses 20, relays 30, first bus bars 405, and second bus bars 50 are arranged in the lower case 115. As shown in Figure 21 , a fuse arrangement section 115A in which the fuses 20 are arranged is formed in the front portion of the lower case 115 and opens upward. The fuse arrangement section 115A is a recessed section with a bottom that can accommodate the main body 21 of the fuse 20.

[0071] 21 and 22, fastening portions N1 and N2 to which bolts B1 and B2 can be fastened are provided on both the front and rear sides of the fuse mounting portion 115A. As shown in FIG. 21, terminal blocks 11B to which fastening portions N1 and N2 such as nuts are fixed are provided on both the front and rear sides of the fuse mounting portion 115A. Terminal portions 22 (an example of a terminal of an electronic component) of the fuse 20 are fastened to the fastening portions N1 and N2. In this embodiment, a heat dissipation member HM is placed on the front fastening portion N1, and the terminal portion 22 is connected to the fastening portion N1 via the heat dissipation member HM, but the heat dissipation member HM may be omitted.

[0072] As shown in FIG. 21 , the rear portion of the lower case 115 is formed with a mounting surface 11C on which the relay 30 is mounted and a positioning portion 11D for positioning the relay 30. The positioning portion 11D is a recess recessed from a side wall portion 11E that rises upward from the right edge of the mounting surface 11C. The partition wall 32 engages with the positioning portion 11D of the lower case 115, thereby positioning the relay 30 relative to the lower case 115. A fastening portion N3, to which a bolt B3 can be fastened, is fixed to the rear end of the lower case 115. Note that the mounting surface 11C of the lower case 115 may further be provided with a fixing portion (not shown) for fixing the relay 30.

[0073] (Fastening Structure of First Bus Bar 405) First bus bar 405 is a member formed by stamping and bending a conductive metal plate material. First bus bar 405 includes an intermediate portion 435 extending in the front-rear direction, a relay connection portion 42 formed at the rear end of intermediate portion 435, and a fuse connection portion 415 formed at the front end of intermediate portion 435.

[0074] The relay connection portion 42 of the first bus bar 405 has an insertion hole 42A through which the bolt B5 is inserted, and the relay connection portion 51 of the second bus bar 50 has an insertion hole 51A through which the bolt B4 is inserted. The bolts B4 and B5 are inserted into the insertion holes 42A and 51A and fastened to the terminals 33 of the relay 30, thereby electrically connecting the first bus bar 405 and the second bus bar 50 via the relay 30.

[0075] The fuse connection portion 415 is connected to the front lower edge of the intermediate portion 435. As shown in FIG. 22 , the fuse connection portion 415 includes a fuse 20, a fastening member (bolt B2, fastening portion N2), a fastening bus bar 605, and a connection bus bar 705. As shown in FIG. 21 , the connection bus bar 705 includes a first horizontal portion 705A extending leftward from the front lower edge of the intermediate portion 435, a first vertical portion 705B extending downward from the left edge of the first horizontal portion 705A, a second horizontal portion 705C extending leftward from the lower edge of the first vertical portion 705B, a second vertical portion 705D extending upward from the rear edge of the second horizontal portion 705C, and a third horizontal portion 705E extending rearward from the upper edge of the second vertical portion 705D. The fuse connection portion 415 corresponds to the "bus bar fastening structure" of the present disclosure.

[0076] The second horizontal portion 705C is disposed corresponding to the fuse mounting portion 115A, while the third horizontal portion 705E of the connection bus bar 705 and the fastening bus bar 605 are disposed corresponding to the rear terminal block 11B. As shown in FIG. 22 , the second horizontal portion 705C contacts the bottom surface of the fuse mounting portion 115A. The second horizontal portion 705C is thermally connected to the heat sink H via the bottom surface of the fuse mounting portion 115A. A thermally conductive sheet may be interposed between the second horizontal portion 705C and the bottom surface of the fuse mounting portion 115A to improve thermal conductivity. The bottom surface of the fuse mounting portion 115A and the heat sink H correspond to the "cooling surface" of the present disclosure. Meanwhile, the third horizontal portion 705E of the connection bus bar 705 does not contact the terminal block 11B, and a predetermined clearance is formed between the third horizontal portion 705E of the connection bus bar 705 and the terminal block 11B.

[0077] The third horizontal portion 705E of the connecting busbar 705 has a bolt relief hole 715 for allowing the bolt B2 and the fastening portion N2 to escape, and a joint portion 725 formed around the bolt relief hole 715. The fastening busbar 605 is joined to the joint portion 725. The area of ​​the fastening busbar 605 excluding the fastened portion 615 that is fastened by the bolt B2 is defined as a busbar joint region 625. The connecting busbar 705 is electrically connected to the busbar joint region 625 by joining. A joint portion 455 is formed between the busbar joint region 625 and the joint portion 725 of the connecting busbar 705. The joining method of the joint portion 455 is the same as that of the joint portion 45 in the first embodiment. The fastening busbar 605 has higher strength than the connecting busbar 705.

[0078] The fastened portion 615 of the fastening bus bar 605 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 705 via the fastening bus bar 605. On the other hand, the external connection bus bar 2 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B1 and the fastening portion N1.

[0079] (Operation and Effect of Fifth Embodiment) The fuse connection portion 415 according to the fifth embodiment includes a fuse 20 having a terminal portion 22 and generating heat when current is applied, fastening members (bolts B1, B2 and fastening portions N1, N2), a fastening bus bar 605 that is fastened to the terminal portion 22 by the fastening members and thereby electrically connected to the fuse 20, and a connection bus bar 705 that is electrically connected to portions of the fastening bus bar 605 excluding a fastened portion 615 that is fastened by the fastening members, and the fastening bus bar 605 has a strength greater than that of the connection bus bar 705. The fuse 20 is electrically connected to the relay 30 via the fastening bus bar 605 and the connection bus bar 705.

[0080] Fastening bus bar 605 is fastened to terminal portion 22 of fuse 20 with a fastening member, thereby electrically connecting fastening bus bar 605 and fuse 20. Although fastening bus bar 605 receives an axial force from the fastening member during fastening, fastening bus bar 605 has a strength higher than that of connection bus bar 705, and therefore deformation of fastening bus bar 605 due to the axial force during fastening can be suppressed.

[0081] Furthermore, because the connection bus bar 705 is electrically connected to the fastening bus bar 605 at locations other than the fastened portion 615 to be fastened by the fastening member, even if the fastening bus bar 605 is slightly deformed, this can prevent deformation of the connection bus bar 705. This allows the connection bus bar 705 to be made of, for example, pure aluminum, thereby reducing the weight of the fuse connection portion 415 and ultimately the electrical junction box JB5.

[0082] Furthermore, according to this embodiment, heat can be dissipated by utilizing the space below the fuse 20. Even if there is no space between the fastening member and the fuse 20, the connection bus bar 705 can be brought into contact with the heat dissipation member H. In Fig. 22, the body 21 of the fuse 20 is in contact with the second horizontal portion 705C, but the body 21 may be spaced apart from the second horizontal portion 705C. In this case, heat generated in the fuse 20 is dissipated to the heat dissipation member H via the terminal portion 22, the fastening bus bar 605, the third horizontal portion 705E, the second vertical portion 705D, the second horizontal portion 705C, and the bottom surface of the fuse mounting portion 115A.

[0083] Examples 10 to 14 Examples 10 to 14 of the present disclosure will be described with reference to Fig. 23 to Fig. 27. The electrical junction boxes JB5 according to Examples 10 to 14 are obtained by partially modifying the fastening structure of the fifth embodiment and are configured substantially similarly to the fifth embodiment, and therefore descriptions of the same components, functions, and effects as the fifth embodiment may be omitted.

[0084] 23 , a fastening bus bar 160 is disclosed as a configuration corresponding to the fastening bus bar 605 of embodiment 5, a connection bus bar 170 is disclosed as a configuration corresponding to the connection bus bar 705 of embodiment 5, and a fuse connection portion 141 is disclosed as a configuration corresponding to the fuse connection portion 415 of embodiment 5. The fuse connection portion 141 includes a fuse 20, fastening members (bolt B2, fastening portion N2), the fastening bus bar 160, and the connection bus bar 170.

[0085] The fastening busbar 160 includes a fastened portion 161 to which the terminal portion 22 of the fuse 20 is connected, a vertical portion 160B extending downward from the front edge of the fastened portion 161, a horizontal portion 160A extending forward from the lower edge of the vertical portion 160B, and a busbar joining region 162 extending rearward of the fastened portion 161. The busbar joining region 162 is located rearward of the rear end of the terminal portion 22. The region of the fastening busbar 160 excluding the fastened portion 161 to be fastened by the bolt B2 is the busbar joining region 162. The connecting busbar 170 has a joined portion 172.

[0086] The horizontal portion 160A contacts the bottom surface of the fuse mounting portion 115A. In FIG. 23 , the main body 21 of the fuse 20 contacts the horizontal portion 160A, but the main body 21 may be spaced apart from the horizontal portion 160A. In this case, heat generated in the fuse 20 is dissipated to the heat sink H via the terminal portion 22, the fastened portion 161, the vertical portion 160B, the horizontal portion 160A, and the bottom surface of the fuse mounting portion 115A. The bottom surface of the fuse mounting portion 115A and the heat sink H correspond to the "cooling surface" in this disclosure. Meanwhile, the busbar bonding region 162 of the fastening busbar 160 does not contact the terminal block 11B, and a predetermined clearance is formed between the busbar bonding region 162 of the fastening busbar 160 and the terminal block 11B.

[0087] The jointed portion 172 of the connection busbar 170 is electrically connected to the busbar joint region 162 by joining. A joint portion 145 is formed between the busbar joint region 162 and the jointed portion 172 of the connection busbar 170. The joining method of the joint portion 145 is the same as that of the joint portion 45 of the first embodiment. The fastening busbar 160 has a higher strength than the connection busbar 170.

[0088] The fastened portion 161 of the fastening bus bar 160 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 170 via the fastening bus bar 160. According to this embodiment, heat can be dissipated without going through the joint portion 145.

[0089] 24 discloses a fastening bus bar 260 as a configuration corresponding to the fastening bus bar 605 of embodiment 5, a connection bus bar 270 as a configuration corresponding to the connection bus bar 705 of embodiment 5, and a fuse connection portion 241 as a configuration corresponding to the fuse connection portion 415 of embodiment 5. The fuse connection portion 241 includes a fuse 20, fastening members (bolt B2, fastening portion N2), the fastening bus bar 260, and the connection bus bar 270.

[0090] The fastening busbar 260 includes a fastened portion 261 to which the terminal portion 22 of the fuse 20 is connected, a busbar joining region 262 extending rearward of the fastened portion 261, a vertical portion 260B extending downward from the rear edge of the busbar joining region 262, and a horizontal portion 260A extending forward from the lower edge of the vertical portion 260B. The busbar joining region 262 is located rearward of the rear end of the terminal portion 22. The region of the fastening busbar 260 excluding the fastened portion 261 to be fastened by the bolt B2 is the busbar joining region 262. The connecting busbar 270 has a joined portion 272.

[0091] The horizontal portion 260A is in contact with the bottom surface of the fuse mounting portion 115A. Heat generated in the fuse 20 is dissipated to the heat sink H via the terminal portion 22, the fastened portion 261, the busbar bonding area 262, the vertical portion 260B, the horizontal portion 260A, and the bottom surface of the fuse mounting portion 115A. The contact area between the horizontal portion 260A and the bottom surface of the fuse mounting portion 115A is larger than the contact area between the horizontal portion 160A and the bottom surface of the fuse mounting portion 115A in Example 10. Therefore, the heat dissipation effect of Example 11 is greater than that of Example 10.

[0092] The jointed portion 272 of the connection busbar 270 is electrically connected to the busbar joint region 262 by joining. A joint portion 245 is formed between the busbar joint region 262 and the jointed portion 272 of the connection busbar 270. The joining method of the joint portion 245 is the same as that of the joint portion 45 of the first embodiment. The fastening busbar 260 has a higher strength than the connection busbar 270.

[0093] The fastened portion 261 of the fastening bus bar 260 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 270 via the fastening bus bar 260.

[0094] 25 discloses a fastening bus bar 360 as a configuration corresponding to the fastening bus bar 605 of embodiment 5, a connection bus bar 370 as a configuration corresponding to the connection bus bar 705 of embodiment 5, and a fuse connection portion 341 as a configuration corresponding to the fuse connection portion 415 of embodiment 5. The fuse connection portion 341 includes a fuse 20, fastening members (bolt B2, fastening portion N2), the fastening bus bar 360, and the connection bus bar 370.

[0095] The fastening busbar 360 includes a fastened portion 361 to which the terminal portion 22 of the fuse 20 is connected, and a busbar joining region 362 extending downward from the front edge of the fastened portion 361. The region of the fastening busbar 360 excluding the fastened portion 361 to which the bolt B2 is fastened is defined as the busbar joining region 362. The connecting busbar 370 includes a joined portion 372 connected to the busbar joining region 362 of the fastening busbar 360, and a horizontal portion 370A extending forward from the lower edge of the joined portion 372.

[0096] The horizontal portion 370A of the connection bus bar 370 is in contact with the bottom surface of the fuse placement portion 115A. Heat generated in the fuse 20 is dissipated to the heat sink H via the terminal portion 22, the fastened portion 361, the bus bar joining region 362, the joined portion 372, the horizontal portion 370A, and the bottom surface of the fuse placement portion 115A. Meanwhile, the fastened portion 361 of the fastening bus bar 360 is not in contact with the terminal portion 11B, and a predetermined clearance is formed between the fastened portion 361 of the fastening bus bar 360 and the terminal portion 11B.

[0097] The jointed portion 372 of the connection busbar 370 is electrically connected to the busbar joint region 362 by joining. A joint portion 345 is formed between the busbar joint region 362 and the jointed portion 372 of the connection busbar 370. The joining method of the joint portion 345 is the same as that of the joint portion 45 of the first embodiment. The fastening busbar 360 has a higher strength than the connection busbar 370.

[0098] The fastened portion 361 of the fastening bus bar 360 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 370 via the fastening bus bar 360.

[0099] 26 discloses a fastening bus bar 460 as a configuration corresponding to the fastening bus bar 605 of embodiment 5, a connection bus bar 470 as a configuration corresponding to the connection bus bar 705 of embodiment 5, and a fuse connection portion 441 as a configuration corresponding to the fuse connection portion 415 of embodiment 5. The fuse connection portion 441 includes a fuse 20, fastening members (bolt B2, fastening portion N2), the fastening bus bar 460, and the connection bus bar 470.

[0100] The fastening busbar 460 includes a fastened portion 461 to which the terminal portion 22 of the fuse 20 is connected, and a busbar joining region 462 extending downward from the rear edge of the fastened portion 461. The region of the fastening busbar 460 excluding the fastened portion 461 to which the bolt B2 is fastened is defined as the busbar joining region 462. The connecting busbar 470 includes a joined portion 472 connected to the busbar joining region 462 of the fastening busbar 460, and a horizontal portion 470A extending rearward from the lower edge of the joined portion 472.

[0101] The horizontal portion 470A of the connection bus bar 470 is in contact with the bottom surface of the fuse mounting portion 115A. Heat generated in the fuse 20 is dissipated to the heat sink H via the terminal portion 22, the fastened portion 461, the bus bar joining region 462, the joined portion 472, the horizontal portion 470A, and the bottom surface of the fuse mounting portion 115A.

[0102] The jointed portion 472 of the connection bus bar 470 is electrically connected to the bus bar joint region 462 by joining. A joint portion 445 is formed between the bus bar joint region 462 and the jointed portion 472 of the connection bus bar 470. The joining method of the joint portion 445 is the same as that of the joint portion 45 of the first embodiment. The fastening bus bar 460 has a higher strength than the connection bus bar 470.

[0103] The fastened portion 461 of the fastening bus bar 460 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 470 via the fastening bus bar 460.

[0104] 27 discloses a fastening bus bar 560 as a configuration corresponding to the fastening bus bar 605 of embodiment 5, a connection bus bar 570 as a configuration corresponding to the connection bus bar 705 of embodiment 5, and a fuse connection portion 541 as a configuration corresponding to the fuse connection portion 415 of embodiment 5. The fuse connection portion 541 includes a fuse 20, fastening members (bolt B2, fastening portion N2), the fastening bus bar 560, and the connection bus bar 570.

[0105] The fastening busbar 560 includes a fastened portion 561 to which the terminal portion 22 of the fuse 20 is connected, a busbar joining region 562 extending downward from the front edge of the fastened portion 561, and a horizontal portion 560A extending forward from the lower edge of the busbar joining region 562. The area of ​​the fastening busbar 560 excluding the fastened portion 561 to be fastened by the bolt B2 is the busbar joining region 562. The connecting busbar 570 includes a joined portion 572 extending in the vertical direction and a horizontal portion 570A extending rearward from the lower edge of the joined portion 572.

[0106] The horizontal portions 560A and 570A are in contact with the bottom surface of the fuse mounting portion 115A. Heat generated in the fuse 20 is dissipated to the heat dissipation member H via the terminal portion 22, the fastened portion 561, the busbar bonding region 562, the horizontal portion 560A, and the bottom surface of the fuse mounting portion 115A. At the same time, the heat branches from the busbar bonding region 562 to the bonded portion 572 and is dissipated to the heat dissipation member H via the horizontal portion 570A and the bottom surface of the fuse mounting portion 115A. The contact area between the horizontal portions 560A and 570A and the bottom surface of the fuse mounting portion 115A is larger than the contact area between the horizontal portion 160A and the bottom surface of the fuse mounting portion 115A in Example 10. Therefore, the heat dissipation effect of Example 14 is greater than that of Example 10.

[0107] The jointed portion 572 of the connection busbar 570 is electrically connected to the busbar joint region 562 by joining. A joint portion 545 is formed between the busbar joint region 562 and the jointed portion 572 of the connection busbar 570. The joining method of the joint portion 545 is the same as that of the joint portion 45 of the first embodiment. The fastening busbar 560 has a higher strength than the connection busbar 570.

[0108] The fastened portion 561 of the fastening bus bar 560 and the terminal portion 22 of the fuse 20 are electrically connected by being fastened with the bolt B2 and the fastening portion N2. Therefore, the terminal portion 22 of the fuse 20 is electrically connected to the connection bus bar 570 via the fastening bus bar 560.

[0109] (Other Embodiments) The above-described first to fifth embodiments can be modified and implemented as follows. The above-described first to fifth embodiments can be combined with each other to the extent that there is no technical contradiction. In the above-described first to fourth embodiments, a relay is given as an example of an electronic component, but the electronic component does not have to be a relay as long as it has the property of generating heat when current is applied. The electronic component may be, for example, a fuse, a resistor, a coil, a capacitor, a diode, an IC (Integrated Circuit), a switching element such as an FET (Field Effect Transistor), or the like. Furthermore, in the above-described fifth embodiment, a fuse is given as an example of an electronic component, but the electronic component does not have to be a fuse.

[0110] In the above-described first to fifth embodiments, the connecting bus bar is directly joined to the fastening bus bar, but the connecting bus bar may be joined to the fastening bus bar via a conductive member such as solder.

[0111] In the second and fourth embodiments, the heat sink portion is formed in the non-current-carrying region, but the heat sink portion may be formed in the current-carrying region.

[0112] In the fourth embodiment, the heat-drawing portion is folded back in a U-shape. However, the heat-drawing portion may be folded back in an L-shape.

[0113] In the third embodiment, the heat-drawing bus bar is fastened to the fastening bus bar. However, as in the fourth embodiment, the heat-drawing portion folded back in a U-shape may be fastened to the fastening bus bar.

[0114] In the above-described first to fifth embodiments, an electrical connection box in which both the fastening bus bar and the connection bus bar are housed inside the case has been exemplified. However, the electrical connection box may also be one in which at least one of the fastening bus bar and the connection bus bar is exposed to the outside of the case.

[0115] The plate thickness of the fastening bus bar may be thicker than that of the connecting bus bar.

[0116] In the fifth embodiment, heat is dissipated from one of the terminal portions 22 . However, heat may be dissipated from both of the terminal portions 22 .

[0117] JB, JB2, JB3, JB4, JB5: Electrical junction box 2, 3: External bus bar 10, 105: Case 11, 115: Lower case 11A, 115A: Fuse placement section (cooling surface) 11B: Terminal block 11C: Mounting surface 11D: Positioning section 11E: Side wall section 12: Upper case 12A: First bus bar accommodating section 12B: Second bus bar accommodating section 20: Fuse (other electronic component) 21: Main body section 22: Terminal section 30: Relay (electronic component) 31: Main body section 32: Partition wall 33: Terminal 34: Recess 40, 405: First bus bar 41: Fuse connection section 141, 241, 341, 415, 441, 541: Fuse connection section (bus bar fastening structure) 42, 422, 423, 424: Relay connection portion (bus bar fastening structure) 42A: Insertion hole 43, 435: Intermediate portion 44: Extension portion 45, 145, 245, 345, 445, 453, 545: Joint portion 50: Second bus bar 51, 512, 513, 514: Relay connection portion 51A: Insertion hole 52: External connection portion 60, 160, 260, 360, 460, 560, 602, 604, 605: Fastening bus bar 160A, 260A, 560A: Horizontal portion 160B, 260B: Vertical portion 61, 161, 261, 361, 461, 561, 615: Fastened portion 62, 162, 262, 362, 462, 562, 625: Busbar joining area 70, 170, 270, 370, 470, 570, 702, 703, 705: Connection busbars 370A, 470A, 570A: Horizontal section 705A: First horizontal section 705B: First vertical section 705C: Second horizontal section 705D: Second vertical section 705E: Third horizontal section 71, 715: Bolt relief holes 72, 172, 272, 372, 472, 572, 725: Joined section 80: Heat dissipation busbar 81: Bolt relief holes B1, B2, B3, B4: Bolts B5, B53: Bolts (fastening members) B51: Bolt head B52: Shank H: Heat dissipation member (cooling surface) H2, H4: Heat dissipation section HM: Heat dissipation member JP1, JP2, JP3, JP4, JP5, JP6, JP7, JP8, JP9: Joint position R1: Current-carrying area R2, R4: Non-current-carrying area

Claims

1. An electronic component having terminals and generating heat upon energization, a fastening member, a fastening bus bar electrically connected to the electronic component by being fastened to the terminals by the fastening member, and a connection bus bar electrically connected to a location of the fastening bus bar excluding the fastened portion fastened by the fastening member. The fastening bus bar has a higher strength than the connection bus bar. A bus bar fastening structure.

2. The fastening member has a bolt head. The connection bus bar has a bolt relief hole for passing the bolt head and a joint portion formed around the bolt relief hole and joined to the fastening bus bar. The bus bar fastening structure according to claim 1.

3. The fastening bus bar has a heat dissipation portion formed in a non-energization region different from an energization region where current flows between the fastening bus bar and the connection bus bar. The bus bar fastening structure according to claim 1.

4. The heat dissipation portion is formed in a folded-back shape. The bus bar fastening structure according to claim 3.

5. The bus bar fastening structure according to claim 1, further comprising a heat dissipation bus bar co-fastened to the fastening bus bar.

6. The fastening bus bar is subjected to surface treatment. The bus bar fastening structure according to claim 1.

7. At least one of the fastening bus bar or the connection bus bar is thermally connected to a cooling surface. The bus bar fastening structure according to claim 1.

8. The thermal conductivity and electrical conductivity of the connection bus bar are higher than those of the fastening bus bar. The bus bar fastening structure according to claim 1.

9. The joint portion between the connection bus bar and the fastening bus bar is at least on the side in the direction of the conductive path when viewed from the fastening direction of the fastening member. The bus bar fastening structure according to claim 2.

10. The joint position between the connection bus bar and the fastening bus bar is arranged along at least two sides around the fastening member. The bus bar fastening structure according to claim 2.

11. An electrical connection box comprising the bus bar fastening structure according to any one of claims 1 to 10 and another electronic component electrically connected to the electronic component via the fastening bus bar and the connection bus bar.

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