Busbar unit and motor unit

Abstract

The present invention addresses the problem of providing a bus bar unit or the like that can keep the board size small without increasing the size of the board connection portion with the bus bar leading to the motor phase current terminal. [Solution] The problem has been solved by a busbar unit that connects a motor phase current terminal and a circuit board, the busbar unit including three busbars and a resin fixing portion, the resin fixing portion having busbar fixing holes for sandwiching the busbar to fix connection terminals of the circuit board, and case fixing holes for fixing the resin fixing portion to a case of the circuit board, the busbar having a motor fixing hole for fixing to the motor phase current terminal, the busbar fixing holes, the case fixing holes, and the motor fixing holes being located at three points that form vertices of a triangle when viewed from above and from the side of the circuit board, and the respective fixing objects being fastened to each other with screws at the three points.

Description

[Technical Field]

[0001] The present invention relates to a busbar unit that connects a motor phase current terminal to a circuit board, and more particularly to a busbar unit that can ensure waterproofing of the mating surfaces between the motor and the circuit board, and a motor unit equipped with the busbar unit. [Background technology]

[0002] BACKGROUND ART Conventionally, as shown in Patent Document 1, for example, a bus bar unit is known as a relay conductor that connects a motor and a circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-124029 Summary of the Invention [Problem to be solved by the invention]

[0004] FIG. 1 shows an example of a motor unit mounted on an electric motorcycle, which includes a conventional busbar unit. FIG. 1(a) is an exploded view for easily understanding the structure of the busbar unit, and FIG. 1(b) is a cross-sectional view for schematically illustrating the connection of the busbar unit. The motor unit is connected to the drive shaft of the drive wheels driven by the motor of the electric motorcycle. In practice, the motor unit is laid flat so that the three exploded elements are aligned horizontally along the axial direction of the motor. In FIG. 1(a), the lower left of the page is the front direction of the vehicle, and the upper right is the rear direction of the vehicle. As shown in FIG. 1(a), a circuit board CB, including an inverter, is housed inside a conventional circuit board case IHP. A motor case MH is provided below the circuit board case IHP, and a motor is housed inside the motor case MH. A conventional busbar unit 100P includes three busbars 1P for connecting the circuit board CB to the motor's U, V, and W phases as motor phase current terminals. The busbar unit 100P also includes a resin fixing portion 2P for fixing the busbar unit 100P to the circuit board case IHP. One busbar unit 100P is provided on each of the left and right sides of the circuit board CB in the drawing to correspond to the current terminals for the U, V, and W phases of the motor. Since the motor unit must be waterproof, the busbar 1P is designed to move in the axial direction of the motor when bolted to the motor to ensure airtightness at the mating surfaces of the motor case MH and the circuit board case IHP.

[0005] As shown in Figure 1(b), the conventional busbar unit 100P includes a busbar 1P enclosed in a resin fixing portion 2P and secured axially to a circuit board case IHP with bolts. The electrical connection between the circuit board CB and the busbar 1P is achieved without soldering by press-fitting numerous press-fit pins attached to the ends of the busbar 1P into the press-fit connection holes PF. While the press-fit connection holes PF are depicted as elongated holes in Figure 1(a), in reality, approximately eight press-fit connection holes are provided per busbar to ensure the required current capacity. The other end of the busbar 1P is bent into a U-shape and secured axially to a motor busbar extending from a motor phase current terminal with bolts. The U-shape bending allows the busbar to deform by a deformation distance Lp, allowing it to follow the axial direction of the motor when the bolts are tightened.

[0006] However, in the conventional busbar unit 100P, the busbar 1P is enclosed in a resin fixing portion 2P, which prevents a long distance from the board connection portion to the motor phase current terminal. Furthermore, the busbar 1P can only be bent at one point. The cylindrical motor unit wall limits the axial deformation distance Lp of the busbar. To reduce board stress, the terminal thickness must be reduced. This limits the motor's output power. Furthermore, the board size increases due to the multiple press-fit connection holes PF. Since the board cannot be axially fixed by press-fit alone, the board and busbar unit must be fixed with bolts at locations other than the press-fit connection holes PF, further increasing the board size. This makes it difficult to increase the size of the mounted components to improve motor output.

[0007] The present invention addresses these problems and aims to provide a busbar unit and a motor unit that can keep the board size small without enlarging the board connection portion with the busbar leading to the motor phase current terminal. [Means for solving the problem]

[0008] In order to achieve this object, the technical means according to the present invention is a busbar unit having at least the following configuration.

[0009] A busbar unit connecting a motor phase current terminal and a circuit board, the busbar unit comprising three busbars and a resin fixing portion, the resin fixing portion having busbar fixing holes for sandwiching the busbar to fix connection terminals of the circuit board, and case fixing holes for fixing the resin fixing portion to a case of the circuit board, the busbar having a motor fixing hole for fixing to the motor phase current terminal, the busbar fixing holes, the case fixing holes, and the motor fixing holes being located at three points that form vertices of a triangle when viewed from above and from the side of the circuit board, and the respective fixing objects being fastened to each other by screws at the three points.

[0010] In order to achieve the above object, the technical means according to the present invention is a motor unit having at least the following configuration.

[0011] A motor unit including a busbar unit that connects motor phase current terminals and a circuit board, the busbar unit including three busbars and a resin fixing portion, the resin fixing portion having busbar fixing holes for sandwiching the busbar to fix connection terminals of the circuit board, and case fixing holes for fixing the resin fixing portion to a case of the circuit board, the busbar having a motor fixing hole for fixing to the motor phase current terminal, the busbar fixing holes, the case fixing holes, and the motor fixing holes being located at three points that form vertices of a triangle when viewed from above and from the side of the circuit board, and the respective fixing objects being fastened to each other by screws at the three points. [Effects of the Invention]

[0012] By virtue of these characteristics, the present invention has the following advantages. By positioning the resin fixing portion to the circuit board case and the circuit board, and the bus bar to the motor phase current terminal at three points that form the vertices of a triangle when viewed from above and from the side, it is possible to provide a bus bar unit and a motor unit that can increase the board mounting area while keeping the board size small. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an exploded perspective view and a partial cross-sectional view of a conventional bus bar unit and a motor unit. [Figure 2] 1 is an exploded perspective view and a partial cross-sectional view of a busbar unit and a motor unit according to an embodiment of the present invention; [Figure 3] 3A and 3B are diagrams showing a busbar unit and a motor unit according to an embodiment of the present invention, in which FIG. 3A is a top view, FIG. 3B is an AA cross-sectional view, FIG. 3C is a BB cross-sectional view, and FIG. 3D is a DD cross-sectional view. [Figure 4] 4A to 4D are diagrams showing a busbar unit according to an embodiment of the present invention housed in a circuit board case, in which FIG. 4A is a bottom view, FIG. 4B is an AA cross-sectional view, FIG. 4C is a BB cross-sectional view, and FIG. 4D is an isometric projection view. [Figure 5] 1A and 1B are diagrams illustrating a busbar unit according to an embodiment of the present invention, which is fastened with screws at three points. [Figure 6] FIG. 1 is an isometric view illustrating a busbar unit according to an embodiment of the present invention. [Figure 7] 7A to 7D are diagrams showing a busbar unit according to an embodiment of the present invention, in which FIG. 7A is a front view, FIG. 7B is a top view, FIG. 7C is a bottom view, and FIG. 7D is a right side view. [Figure 8] FIG. 10 is an isometric view illustrating a busbar unit according to another embodiment of the present invention. [Figure 9] 9A to 9D are diagrams showing a busbar unit according to another embodiment of the present invention, in which FIG. 9A is a front view, FIG. 9B is a top view, FIG. 9C is a bottom view, and FIG. 9D is a right side view. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, examples of embodiments of a busbar unit and a motor unit according to the present invention will be described with reference to the drawings. However, the drawings below have been created for the purpose of explanation, and for the sake of clarity, components not necessary for the explanation may be intentionally omitted. Furthermore, components may be intentionally enlarged or reduced in size for the purpose of explanation, and the drawings are not drawn to an accurate scale. In the following description, the same reference numerals in different drawings indicate parts with the same function, and duplicate explanations in each drawing will be omitted as appropriate.

[0015] <Embodiments of the present invention> (Overall composition) FIG. 2 is an exploded perspective view and a partial cross-sectional view of a busbar unit and a motor unit according to an embodiment of the present invention. FIG. 3 shows a busbar unit and a motor unit according to an embodiment of the present invention, where FIG. 3(a) is a top view, FIG. 3(b) is an AA cross-sectional view, FIG. 3(c) is a BB cross-sectional view, and FIG. 3(d) is a DD cross-sectional view. FIG. 4 shows a busbar unit according to an embodiment of the present invention housed in a circuit board case, where FIG. 4(a) is a bottom view, FIG. 4(b) is an AA cross-sectional view, FIG. 4(c) is a BB cross-sectional view, and FIG. 4(d) is an isometric projection view. FIG. 5 is a schematic diagram showing a busbar unit according to an embodiment of the present invention fastened with screws at three points. FIG. 6 is an isometric projection view of a busbar unit according to an embodiment of the present invention. FIG. 7 shows a busbar unit according to an embodiment of the present invention, where FIG. 7(a) is a front view, FIG. 7(b) is a top view, FIG. 7(c) is a bottom view, and FIG. 7(d) is a right side view.

[0016] FIG. 2 shows an example of a motor unit mounted on an electric motorcycle, which includes a busbar unit 100 according to an embodiment of the present invention. FIG. 2(a) is an exploded view for easily understanding the structure of the busbar unit, and FIGS. 2(b) and 2(c) are cross-sectional views for schematically illustrating the connection of the busbar unit. FIG. 2(b) is a cross-sectional view taken along arrow S in FIG. 2(a), and FIG. 2(c) is a cross-sectional view taken along arrow T in FIG. 2(a). The motor unit is connected to the drive shaft of the drive wheels driven by the motor of the electric motorcycle. In actual use, the motor unit is laid flat so that the three elements shown exploded in FIG. 2(a) are aligned horizontally. In FIG. 2(a), the lower left of the page is the front of the vehicle, and the upper right is the rear of the vehicle. As shown in FIG. 2(a), a circuit board CB, such as an inverter, is housed inside a circuit board case IH. A motor case MH is provided below the circuit board case IH, and a motor is housed inside the motor case MH. A busbar unit 100 according to an embodiment of the present invention includes three busbars 11, 12, and 13 for connecting a circuit board CB to the motor's U-, V-, and W-phase current terminals. The busbar unit 100 also includes a resin fixing portion 2 for fixing the busbar unit 100 to a circuit board case IH. Two busbar units 100 are provided on opposite sides of the circuit board CB, one on each side as viewed in the drawing, to correspond to the motor's U-, V-, and W-phase current terminals. The circuit board case IH has a heat dissipation member on its top surface, which functions as a heat sink, efficiently dissipating heat generated by the circuit board CB housed therein through a combination of thermal conduction, convection, and radiation. The heat dissipation member has also been improved from conventional models, with vertical fins divided along the running direction and with different inter-fin distances between each divided fin.

[0017] The busbar unit 100 is composed of three busbars 11, 12, and 13 and one resin fixing part 2. The three busbars 11, 12, and 13 are connected to the U-phase, V-phase, and W-phase of the motor, and are bent at least in two places to increase the deformation distance from the connection terminals of the circuit board CB to the motor phase current terminals. Specifically, the central busbar 11 is bent into an S-shape as shown in FIGS. 2(b) and 7(d), and the left and right busbars 12 and 13 are bent into a U-shape as shown in FIGS. 2(c) and 7(c). 2(a), 6(a), etc., the resin fixing portion 2 has three rectangular parallelepipeds with busbar fixing holes HB for fixing the connection terminals of the circuit board CB by sandwiching the busbars 11, 12, and 13 therebetween, and two cylinders with case fixing holes HC for fixing the resin fixing portion 2 itself to the circuit board case IH, and the two cylinders are arranged in a staggered pattern between the three rectangular parallelepipeds, thereby connecting the three rectangular parallelepipeds and the two cylinders. The resin fixing portion 2 is fixed to the circuit board case IH by screwing case fixing bolts 32 into the case fixing holes HC.

[0018] Each of the three bus bars 11, 12, and 13 has a connection hole at one end and the other end. The connection hole at one end of the bus bar is aligned with the bus bar fixing hole HB of the resin fixing portion 2 and the connection terminal of the circuit board CB, and then the bus bar is screwed together with a bus bar fixing bolt 31. This ensures that the axial force of the bolt ensures a reliable electrical connection between the bus bar and the connection terminal of the circuit board. The motor fixing hole HM, which is a connection hole at the other end of the bus bar, is aligned with the motor bus bar MB extending from the motor phase current terminal, and the bus bars 11, 12, and 13 and the motor bus bar MB are overlapped and then screwed together with a motor bus bar fixing bolt 33.

[0019] While conventional busbar 1P is wrapped in resin as shown in Fig. 1(b), busbars 11, 12, and 13 of this embodiment are not covered by resin fixing portion 2, but are arranged on the upper surface of resin fixing portion 2 at the positions of busbar fixing holes HB as shown in Fig. 2(b) and Fig. 2(c). The areas around busbar fixing holes HB form electrical connection points between circuit board CB and busbars 11, 12, and 13.

[0020] 1(a) and 1(b), in a conventional busbar unit 100P, the number of press-fit pins was increased to ensure the necessary current capacity, and the area of ​​the circuit board was eroded by the amount of the busbar 1P enclosed in resin, resulting in a relatively small board mounting area.In the busbar unit 100 of this embodiment, as shown in FIG. 2(b), the busbar protrudes from the resin, and the axial force of the bolts establishes an electrical connection between the connection terminals of the circuit board and the busbar, so the area eroded from the circuit board is small, making it possible to relatively increase the board mounting area.

[0021] In the conventional busbar unit 100P, the busbar 1P is bent at one location, as shown in FIG. 1(b), and the busbar deformation distance Lp is small. Therefore, to facilitate busbar deformation and reduce board stress, the terminal thickness Tp must be reduced. In contrast, in the busbar unit 100 of this embodiment, the busbar 11 is bent at two locations in an S-shape, as shown in FIGS. 2(b) and 7(d), and the busbars 12 and 13 are bent at two locations in a U-shape, as shown in FIGS. 2(c) and 7(c). The deformation distance L is greater than the deformation distance Lp of the conventional busbar unit 100P. Because the busbars are sufficiently easy to deform and the stress on the board is sufficiently reduced, there is no need to significantly reduce the terminal thickness T. As a result, the current capacity can be increased, enabling improved motor output.

[0022] In this embodiment, it is possible to keep the board size small without increasing the size of the board connection portion with the bus bar leading to the motor phase current terminal. In other words, for the same board size, it is possible to increase the board mounting area by using the bus bar unit 100 of this embodiment compared to using the conventional bus bar unit 100P. This will be explained using FIG. 5.

[0023] As shown in Figure 5(a), the busbar fixing holes HB, the case fixing holes HC, and the motor fixing holes HM are located at the three vertices of a triangle when viewed from above the circuit board. This arrangement at the three vertices of a triangle is possible because, as shown in Figure 5(b), the busbar fixing holes HB, the case fixing holes HC, and the motor fixing holes HM are located at the three vertices of a triangle when viewed from the side of the circuit board, thereby allowing for efficient placement in a small space. Furthermore, the busbar fixing holes HB, the case fixing holes HC, and the motor fixing holes HM can all be placed within the bowl-shaped area formed by the inner periphery of the circuit board case IH and the outer periphery of the circuit board CB. As a result, the area of ​​the circuit board that is encroached upon is small, allowing for a larger board mounting area.

[0024] In this embodiment, a further measure is taken to ensure a reliable connection between the circuit board CB and the motor phase current terminals. That is, as shown in Figures 3(b) and 3(c), the motor fixing holes HM of the bus bars are positioned away from the mating surfaces of the circuit board case IH and the motor case MH. This ensures airtightness of the mating surfaces of the circuit board case IH and the motor case MH while joining the bus bars 11, 12, and 13 to the motor bus bar MB.

[0025] (Busbar shape details) The busbar unit 100 has three busbars 11, 12, and 13 that connect the connection terminals of the circuit board CB to the motor phase current terminals. As shown in Figures 6(a) and 7(a), the central busbar 11 has a straight path from the busbar fixing hole HB to the motor fixing hole HM in front view, while as shown in Figures 6(b) and 7(d), the path from the busbar fixing hole HB to the motor fixing hole HM in side view is S-shaped.

[0026] As shown in Figures 6(a) and 7(a), the left and right bus bars 12, 13 are flat plates that extend from the bus bar fixing holes HB parallel to the central bus bar 11, but change direction midway and are bent so that only one side of the bus bar 11 rises at a 90-degree angle, and the rising portion is further bent at a 90-degree angle to the opposite side. Thus, the bent portions of the bus bars 12 and 13 are U-shaped, as shown in Figure 7(c).

[0027] The two types of busbar bending patterns are shown in Figures 2(b) and 2(c). Busbar 11 is bent in two S-shapes, and busbars 12 and 13 are bent in two U-shapes. Because the deformation distance L is larger than that of conventional busbar units, the busbars are easily deformed, and stress on the circuit board is sufficiently reduced. Therefore, even busbars with a large terminal thickness T can reduce stress on the circuit board, ensuring the necessary current capacity and improving motor output.

[0028] Unlike conventional press-fit connections, the busbars 11, 12, and 13 are mechanically connected to the circuit board CB at the busbar fixing holes HB by directly fixing the busbar contact surfaces to the circuit board CB using the axial force of the busbar fixing bolts 31, as shown in the partially enlarged view of FIG. 4(b), and a large conductive area can be ensured. This leads to a reduction in the connection pattern area. Specifically, the conventional busbar unit 100P illustrated in FIG. 1 requires eight press-fit pins, so the cross-sectional area of ​​the connection portion per busbar is 2.5 cm2. 2In contrast, in the busbar unit 100 of this embodiment, the connection is direct around the bolt, so the cross-sectional area of ​​the connection per busbar is 0.8 cm 2 The busbars 11, 12, and 13 are also bonded to the pattern near the FET on the circuit board CB (not shown), thereby suppressing heat generation by the FET and the pattern. When using a conventional busbar unit, the busbars are encased in resin, thereby eroding the circuit board area and reducing the board mounting area. However, when using the busbar unit of this embodiment, the busbars protrude from the resin, as shown in FIG. 4(d), reducing the area eroded by the circuit board area. As a result, the board mounting area indicated by the dotted line is increased. This also provides a secondary benefit. The reduced cross-section of the connection creates more space on the board, allowing multiple signal lines to be laid out on the board, enabling inexpensive functional expansion. Specifically, it is now possible to lay out multi-pole, multi-signal signal lines from the outside, avoiding the board connection area, from the power terminal side to the signal element located on the opposite side of the motor centerline. In recent electric motorcycles, there is a demand for motors with higher output and functionality, and the increase in board mounting area achieved by this embodiment contributes greatly to meeting this demand.

[0029] <Another embodiment of the present invention> 8 and 9 are diagrams illustrating another embodiment of the present invention. Fig. 8 is an isometric projection view illustrating a busbar unit according to another embodiment of the present invention. Fig. 9 is a diagram illustrating a busbar unit according to another embodiment of the present invention, in which Fig. 9(a) is a front view, Fig. 9(b) is a top view, Fig. 9(c) is a bottom view, and Fig. 9(d) is a right side view.

[0030] The busbar unit 100A of this alternative embodiment is similar to the previously described embodiment in that it is composed of three busbars 11, 12A, and 13A and one resin fixing portion 2, the three busbars 11, 12A, and 13A are connected to the U phase, V phase, and W phase of the motor, and are bent at least in two places so that the deformation distance from the connection terminal of the circuit board CB to the motor phase current terminal is increased.

[0031] As shown in Fig. 9(a), the central bus bar 11 is arranged such that the path from the bus bar fixing hole HB to the motor fixing hole HM is linear in front view, while the path from the bus bar fixing hole HB to the motor fixing hole HM is S-shaped in side view, as shown in Fig. 8(a) and Fig. 8(b). This is also the same as in the previously described embodiment.

[0032] In the busbar unit 100A of this embodiment, the left and right busbars 12A and 13A have an S-shaped path from the busbar fixing hole HB to the motor fixing hole HM in a side view, as shown in Figures 8(a) and 8(b), and then the upper surfaces of the left and right busbars 12A and 13A change direction within the same plane. In this way, the bent portions of the busbars 11, 12A, and 13A have the same overlapping S-shape in a side view, as shown in Figure 9(d).

[0033] The three busbars are all bent in an S-shape at two locations, with a larger deformation distance than conventional busbar units. This allows for easy busbar deformation and sufficient reduction in stress on the board. This reduces board stress even for busbars with a large terminal thickness T, ensuring the necessary current capacity and improving motor output. From the description of the alternative embodiment, it will be understood that a busbar structure that achieves a large deformation distance can be achieved not only by combining an S-shape and a U-shape, but also by an S-shape alone. In other words, any shape can be adopted as long as the busbar is bent in multiple directions.

[0034] The busbar unit and the motor unit according to the embodiment and other embodiments of the present invention have been described in detail above. However, the specific configurations are not limited to these embodiments, and the present invention also includes design changes within the scope of the present invention without departing from the gist of the present invention. For example, the number of bending positions does not have to be limited to two, but may be three, four, or even more. In order to increase the deformation distance, it is actually preferable to have more bending positions. However, when considering the manufacturing costs associated with the processing and the amount of deformation that is actually required, two bending positions can be said to be an appropriate number. Furthermore, the location where the heat dissipation member and power supply unit are located is not limited to the drive shaft of the drive wheels of an electric motorcycle motor, and the present invention also covers the engine compartment of an automobile. Furthermore, the busbar unit of the present invention is effectively applicable to connection modes that require the tips of the busbars to follow the vertical direction of the circuit board. In other words, the busbar unit of the present invention and this embodiment can be applied to devices other than motor units. [Explanation of symbols]

[0035] 11 Busbar 12 Busbar 12A busbar 13 Busbar 13A busbar 2 Resin fixing part 31 Busbar fixing bolt 32 Case fixing bolt 33 Motor bus bar fixing bolt 100 Busbar Unit 100A busbar unit HB busbar fixing hole HC case fixing hole HM motor fixing hole IH circuit board case MH motor case CB circuit board MB Motor Bus Bar 1P Conventional busbar 2P Conventional resin fixing part 100P Conventional busbar unit IHP Conventional Circuit Board Case

Claims

1. A bus bar unit that connects a motor phase current terminal and a circuit board, the bus bar unit includes three bus bars and a resin fixing portion; the resin fixing portion has bus bar fixing holes for fixing connection terminals of the circuit board with the bus bar sandwiched therebetween, and case fixing holes for fixing the resin fixing portion to a case of the circuit board, the bus bar has a motor fixing hole for fixing to the motor phase current terminal, the bus bar fixing holes, the case fixing holes, and the motor fixing holes are located at three points that form vertices of a triangle when viewed from above and from the side of the circuit board, At the three points, the respective fixed objects are fastened together with screws. A busbar unit characterized by:

2. The bus bar is bent at least at two locations, so that a deformation distance from the connection terminal of the circuit board to the motor phase current terminal is large. The busbar unit according to claim 1 .

3. The bus bar is bent into an S-shape or a U-shape. The busbar unit according to claim 2 .

4. The motor fixing holes are set at positions spaced apart from the mating surfaces of the circuit board case and the motor case, thereby ensuring airtightness of the mating surfaces. The busbar unit according to claim 1 .

5. The bus bar is not covered by the resin fixing portion, but is disposed on the upper surface of the resin fixing portion at the position of the bus bar fixing hole, and the periphery of the bus bar fixing hole also serves as an electrical connection point. The busbar unit according to claim 1 .

6. A bus bar unit according to any one of claims 1 to 5. A motor unit for vehicle use.

7. the circuit board is rectangular, the motor case of the motor unit is cylindrical, and the case of the circuit board is cylindrical and has the same cross section as the motor case; The bus bar fixing holes, the case fixing holes, and the motor fixing holes are all arranged within a bowl-shaped region formed by the inner periphery of the case of the circuit board and the outer periphery of the circuit board.

7. The motor unit according to claim 6.

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