Bus bar unit

Abstract

To increase positioning accuracy of a terminal unit while reducing an axial dimension of a connection of a busbar unit and the terminal unit.SOLUTION: A motor 1 is disposed at one end side of a stator core 21 and has a busbar unit 24 in which a copper busbar 29 is embedded in a body part 28 made of synthetic resin. A terminal unit 31 including a connection terminal 34 electrically connected with an external power source is attached to the body part 28 of the busbar unit 24. At an end 28a of the body part 28, a concavity 39 is provided in which the busbar 29 is arranged in a partially exposed manner. At the terminal unit 31, a projection part 38 fitting in the concavity 39 and arranged facing the busbar 29 in an exposed state is projected. The terminal unit 31 is attached to the busbar unit 24 with an apical surface 38a of the projection part 38 directly facing the busbar 29.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a bus bar unit for supplying power to an electric motor, and particularly to a joining structure between the bus bar unit and a terminal unit attached thereto.

Background Art

[0002] In a brushless motor, a bus bar unit including a metal conductive member called a bus bar may be used as a power supply means for a coil. As described in Patent Document 1, the bus bar unit generally has a configuration in which a plurality of bus bars are embedded in a resin molded body formed in a substantially annular shape in a mutually insulated state. For example, when the coils are connected in a star connection method, a plurality of phase bus bars for supplying power to the coils of each phase and a neutral point bus bar forming a neutral point (common) are embedded in the resin molded body to constitute the bus bar unit.

[0003] Further, a terminal unit may be further attached to the bus bar unit for electrical connection between the bus bar unit and the motor power supply unit (external power source). At that time, a configuration in which the terminal unit is arranged on the axial end surface of the bus bar unit is assumed in the layout of the motor, and there, the terminal unit is attached to the end surface of the bus bar unit. FIG. 8 is an explanatory view showing a state in which a terminal unit is attached to the end surface of a bus bar unit with a conventional joining structure, and FIG. 9 is an explanatory view showing a cross-sectional image of the bus bar and the terminal unit in the case of FIG. 8.

[0004] As shown in Fig. 8, a terminal unit 62 formed separately from the bus bar unit is attached to the end face (the upper face in the figure) of the bus bar unit 61. The bus bar unit 61 is provided with a plurality of power supply terminals 63 for each phase (here, a total of 4, including 3 for 3 phases and 1 for each phase connection). Each power supply terminal 63 is integrally formed with the bus bar 64 and is electrically conductive. Also, the terminal unit 62 is provided with a plurality of connection terminals 65 for each phase. When the terminal unit 62 is placed on the bus bar unit 61, each connection terminal 65 faces the corresponding power supply terminals 63 of the same phase.

[0005] On the other hand, as shown in Fig. 9, the bus bar unit 61 and the terminal unit 62 are connected at a fitting joint portion 66 provided between them. The fitting joint portion 66 is composed of a concave groove 67 formed on the bus bar unit 61 side and a protrusion 68 protruding on the terminal unit 62 side. The terminal unit 62 is attached to the bus bar unit 61 in a radially positioned state by fitting the protrusion 68 into the concave groove 67. Then, in this state, the connection terminals 65 and the power supply terminals 63 are welded respectively, so that the external power source and the bus bar 64 are electrically connected.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the case of the configurations shown in FIGS. 8 and 9, the axial height of the connection portion between the bus bar unit 61 and the terminal unit 62 becomes larger by the thickness of the fitting joint portion 66. That is, in the fitting joint portion 66, the resin-coated portion 69 provided at the bottom of the concave groove 67 on the bus bar unit 61 side and the protrusion 68 on the terminal unit 62 side overlap. For this reason, there has been a problem that the axial dimension of the motor increases by that amount. Further, in the configurations shown in FIGS. 8 and 9, although positioning in the radial direction is possible, there has also been a problem that another positioning structure is further required to accurately position in the circumferential direction.

[0008] An object of the present invention is to reduce the axial dimension of the connection portion between the bus bar unit and the terminal unit and to improve the positioning accuracy of the terminal unit.

Means for Solving the Problems

[0009] The bus bar unit of the present invention is arranged on one end side of a stator core, and has a main body portion made of synthetic resin and a bus bar made of metal that is integrated with the main body portion and electrically connected to a stator coil. The bus bar unit is a bus bar unit to which a terminal unit having a connection terminal electrically connected to an external power source is attached. The main body portion includes a recess in which a part of the bus bar is exposed, and the terminal unit includes a protrusion that is arranged to face the exposed bus bar by fitting into the recess.

[0010] Another bus bar unit of the present invention is arranged on one end side of a stator core, and has a main body portion made of synthetic resin and a bus bar made of metal that is integrated with the main body portion and electrically connected to a stator coil. The bus bar unit is a bus bar unit to which a terminal unit having a connection terminal electrically connected to an external power source is attached. The terminal unit includes a recess in which a part of the connection terminal is exposed, and the main body portion includes a protrusion that is arranged to face the exposed bus bar by fitting into the recess.

[0011] In the bus bar unit, a wall portion surrounding the radial direction and the circumferential direction of the recess may be provided in the recess, and the protrusion may be attached to the recess in a state where movement in the radial direction and the circumferential direction is restricted by the wall portion. Thereby, by fitting the protrusion and the recess, the position between the bus bar unit and the terminal unit is accurately positioned.

Advantages of the Invention

[0012] According to the bus bar unit of the present invention, a recess in which a part of the bus bar is exposed is provided in the main body portion of the bus bar unit, and a protrusion that fits into the recess of the bus bar unit and faces the exposed bus bar is provided in the terminal unit attached to the bus bar unit. Therefore, the terminal unit can be attached to the bus bar unit with the protrusion facing the bus bar. For this reason, the thickness of the resin-coated portion of the bus bar existing in the conventional bus bar unit can be reduced, and accordingly, the axial dimension of the stator can be made smaller than before, and the short-axis of the motor can be achieved.

[0013] According to another bus bar unit of the present invention, a recess in which a part of the connection terminal is exposed is provided in the terminal unit, and a protrusion that fits into the recess of the terminal unit and faces the exposed connection terminal is provided in the main body portion of the bus bar unit. Therefore, the terminal unit can be attached to the bus bar unit with the protrusion facing the connection terminal. For this reason, the thickness of the resin-coated portion of the bus bar existing in the conventional bus bar unit can be reduced, and accordingly, the axial dimension of the stator can be made smaller than before, and the short-axis of the motor can be achieved.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0015] (Embodiment 1) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a brushless motor 1 (hereinafter abbreviated as motor 1) employing a bus bar unit which is Embodiment 1 of the present invention. As shown in FIG. 1, the motor 1 is an inner rotor type brushless motor having a stator (stator) 2 on the outside and a rotor (rotor) 3 on the inside, and is used as a drive source for, for example, an electric power steering device.

[0016] As shown in FIG. 1, the stator 2 is fixed inside a motor housing 4 formed in a bottomed cylindrical shape of iron or the like by press-fitting or the like. A bearing holder plate 6 for holding a bearing 5a is attached to the opening on the right end side of the motor housing 4 in FIG. 1. Also, a bearing 5b is attached to the left end side. The bearing 5a is fixed to a bearing holder 7 attached to the central portion of the bearing holder plate 6, and the bearing 5b is fixed to a bearing fixing portion 8 formed at the center of the bottom of the motor housing 4, respectively. A rotor shaft (rotating shaft) 9 is pivotally supported by the bearings 5a and 5b. Inside the stator 2, a rotor 3 fixed to the rotor shaft 9 is rotatably inserted.

[0017] The rotor 3 includes a rotor core 11 fixed to the rotor shaft 9, a plurality (here, 10) of magnets 12 attached to the outer peripheral portion of the rotor core 11, and a magnet cover 13 for preventing scattering attached to the outer periphery of the magnet 12. The rotor core 11 has a structure in which a plurality of circular thin plate-shaped core plates (steel plate materials) formed of electromagnetic steel sheets or the like are laminated, and is press-fitted and fixed to the rotor shaft 9.

[0018] A magnet holder 14 is attached to the left end portion in the figure of the rotor core 11 in a manner fixed to the rotor shaft 9. The magnet holder 14 is provided with 10 holder arms (not shown) extending along the axial direction. The holder arms are disposed on the outer peripheral portion of the rotor core 11, and the magnets 12 are attached to the outer periphery of the rotor core 11 at equal intervals while being sandwiched by the holder arms. Further, a magnet cover 13 formed of iron or the like is attached so as to cover the magnet 12 on the outside of the magnet 12.

[0019] On the right end side of the rotor shaft 9 in the drawing, a sensor magnet 15 for detecting the rotation angle of the motor 1 is attached. The sensor magnet 15 is adhesively fixed to a sensor magnet holder 16 press-fitted and fixed to the right end portion of the rotor shaft 9 in the drawing. Also, on the left end side of the rotor shaft 9, a joint 17 connected to a driven device (not shown) driven by the motor 1 is attached.

[0020] Figure 2 is an explanatory diagram showing the configuration of the stator 2. As shown in Figure 2, the stator 2 includes a stator core 21, a stator coil 23 (hereinafter abbreviated as coil 23) wound around the teeth 22 of the stator core 21, and a bus bar unit 24 attached to the stator core 21. The stator core 21 is formed by laminating thin plates made of electromagnetic steel sheets or the like, and a plurality of (12 in this embodiment) teeth 22 project radially inward. Slots 25 are formed between adjacent teeth 22, and the stator 2 has a 12-slot configuration. Thus, the motor 1 of this embodiment has a 10-pole 12-slot (10P12S) configuration.

[0021] An insulator 26 made of synthetic resin is attached to the stator core 21, and the coil 23 is wound outside the insulator 26. The coil 23 is wound around the teeth 22 via the slots 25. Figure 3 is an explanatory diagram showing the winding form of the coil 23. In the motor 1, coils 23 of the same phase are arranged adjacent to each other (coils 23p, 23q) and are continuously wound with a single copper wire. In this case, the adjacent coils 23p, 23q of the same phase need to have opposite winding directions. As shown in Figure 3(a), it starts winding from the starting point S on the coil 23p side, and after finishing winding the coil 23p, it moves to the inner diameter side of the adjacent tooth 22 via the jumper wire 27, and winds the coil 23q and finishes winding at the end point F.

[0022] Here, in the conventional motor, when starting to wind the first coil 71p from the starting point S on the outer diameter side of the stator core, as shown in Fig. 3(b), after winding the coil 71p, the jumper wire 72 is introduced to the outer diameter side of the tooth and the coil 71q is wound. However, in such a winding form, since the jumper wire 72 exists at the outermost diameter part of the coil 71q, a region Z where the coil cannot be wound is generated. For this reason, there is a problem that a wasted space (the part of the region Z) is formed in the slot 73, and the coil fill factor is reduced.

[0023] On the other hand, as shown in Fig. 3(a), for the coil 23 of the motor 1, the starting point of the winding of the second coil 23q is set on the inner diameter side of the core, the jumper wire 27 is introduced from the coil 23p side to the tip part of the adjacent tooth 22, and the coil 23q is wound. As a result, a wasted space such as the region Z is not generated in the slot 25, and the second coil 23q can be wound without being affected by the jumper wire 27. Therefore, the coil fill factor can be improved, and both coils 23p and 23q can be wound with the same fill factor. Further, along with the improvement of the fill factor, the coil thickening can be suppressed, and the contact between adjacent coils during core aggregation when adopting a split core can also be suppressed.

[0024] A bus bar unit 24 is attached to one end side of the stator core 21 (the right end opening side of the motor housing 4). The bus bar unit 24 has a configuration in which a metal (copper) bus bar 29 is embedded by insert molding in a main body portion 28 made of synthetic resin. The bus bars 29 are provided in a number corresponding to the number of phases of the motor 1 (here, a total of 4, including 3 for the U phase, V phase, and W phases and 1 for each phase connection). A plurality of power supply terminals 29a project radially outward on the outer peripheral portion of each bus bar 29 and protrude from the bus bar unit 24. The power supply terminal 29a is welded to the end portion 23a of the coil 23 drawn out from the stator core 21 side. Each coil 23 is electrically connected to the power supply terminal 29a corresponding to its phase. After attaching the bus bar unit 24, the stator core 21 is press-fitted and fixed in the motor housing 4.

[0025] In addition, a terminal unit 31 used for connection to an external power source is attached to the bus bar unit 24. A terminal unit attachment portion 32 is provided at an end portion (the right end portion in FIG. 1 and the upper end portion in FIG. 2) 28a of the main body portion 28 of the bus bar unit 24, and the terminal unit 31 is joined to this terminal unit attachment portion 32. FIG. 4 is an explanatory diagram showing the configuration of the terminal unit 31, FIG. 5 is an explanatory diagram showing the state when the terminal unit 31 is attached to the bus bar unit 24, and FIG. 6 is an explanatory diagram showing a cross-sectional image of the bus bar 29 and the terminal unit 31 when the terminal unit 31 is attached to the bus bar unit 24.

[0026] As shown in FIG. 4, the terminal unit 31 is composed of a base portion 33 made of synthetic resin and connection terminals 34 attached to the base portion 33. Three (34U, 34V, 34W) copper connection terminals 34 are attached to the base portion 33. The connection terminals 34 are generally U-shaped as a whole, and are composed of long and short terminal pieces 34a, 34b and a base portion 34c connecting both terminal pieces 34a, 34b, and are fixed to the base portion 33 at the base portion 34c. The long terminal piece 34a of the connection terminal 34 is arranged on the outer side in the radial direction of the bus bar unit 24, and is connected to the power terminal 36 of the harness 35 for external power source connection as shown in FIG. 1. Also, the short terminal piece 34b is arranged on the inner side in the radial direction of the bus bar unit 24, and when the terminal unit 31 is attached onto the bus bar unit 24, it faces the power supply terminals 37 (37U, 37V, 37W) of each phase bus bar 29.

[0027] In FIG. 4 of the terminal unit 31, a protrusion 38 is provided on the lower surface side. The protrusion 38 is adapted to fit into a recess 39 formed in the terminal unit mounting portion 32 of the bus bar unit 24, and a fitting joint portion 41 is formed by the recess 39 and the protrusion 38. In this case, the recess 39 of the terminal unit mounting portion 32 is provided in a form that partially cuts out the end portion 28a of the main body portion of the bus bar unit 24, and a part of the bus bar 29 is exposed at the bottom of the recess 39. The outer side in the radial direction of the recess 39 is an outer peripheral wall (wall portion) 42, and the inner side is an inner peripheral wall (wall portion) 43. Also, the circumferential end portions of the recess 39 are side walls (wall portions) 44, 45.

[0028] The terminal unit 31 is attached to the terminal unit mounting portion 32 in a form that covers the exposed bus bar 29 by fitting the protrusion 38 into the recess 39. And in this state, the power supply terminals 37U, 37V, 37W of each phase of the bus bar 29 and each terminal piece 34b of the terminal unit 31 are welded respectively. Thereby, the external power supply and each phase bus bar 29 are electrically connected, and power supply to each phase coil 23 becomes possible.

[0029] Thus, in the motor 1, the bus bar 29 is arranged in a state of facing the outside at the recess 39 of the terminal unit mounting portion 32. As described above, in the conventional configuration as shown in FIGS. 8 and 9, since there is a resin coating portion 69 above the bus bar 64, the thickness of the fitting joint portion 66 increases accordingly. In contrast, in the bus bar unit 24, the bus bar 29 is in an exposed state within the recess 39, and there is no resin coating portion above it. For this reason, as shown in FIG. 6, the terminal unit 31 is attached to the bus bar unit 24 in a form that the tip surface 38a of the protrusion 38 directly faces or is in close contact with the bus bar 29. As a result, in the motor 1, the thickness corresponding to the resin coating portion 69 in FIG. 9 is reduced, and accordingly, the thickness of the fitting joint portion 41 is suppressed compared to the configuration of FIG. 9. Thereby, the motor 1 can make the axial dimension of the stator 2 smaller than before, and it becomes possible to shorten the axis of the motor.

[0030] Further, in the concave portion 39, an outer peripheral wall 42 and an inner peripheral wall 43 are provided in the radial direction, and side walls 44 and 45 are provided in the circumferential direction. That is, the concave portion 39 is surrounded by wall portions on all four sides, and the protruding portion 38 of the terminal unit 31 is attached thereto in a state where movement in the radial direction and the circumferential direction is restricted. For this reason, the terminal unit 31 is attached to the terminal unit mounting portion 32 in a state where it is positioned not only in the radial direction but also in the circumferential direction. Therefore, in the motor 1, the terminal unit 31 is positioned simply by fitting the protruding portion 38 into the concave portion 39, and the positioning accuracy of the terminal unit 31 is improved. As a result, it becomes possible to accurately arrange the terminal unit 31 in the motor without providing a separate positioning structure.

[0031] (Embodiment 2) In the above-described Embodiment 1, the bus bar unit 24 side is the concave portion 39 and the terminal unit 31 side is the protruding portion 38. However, the concave-convex relationship may be reversed, and a protruding portion may be provided on the bus bar unit 24 side and a concave portion may be provided on the terminal unit 31. FIG. 7 is an explanatory diagram showing a cross-sectional image of a bus bar and a terminal unit when the bus bar unit according to Embodiment 2 of the present invention is used. In Embodiment 2, the same parts and members as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0032] As shown in FIG. 7, in the bus bar unit 51 according to Embodiment 2, a protruding portion 52 is provided on the bus bar unit 51 side, and a concave portion 54 is provided on the terminal unit 53 side. The concave portion 54 is surrounded by wall portions (here, only the radial side walls 55 and 56 are shown, and the inner and outer peripheral walls are not shown). A part of the connection terminal 34 (a part of the base portion 34c) is disposed in the concave portion 54 in a state of being exposed to the outside. On the other hand, a terminal unit mounting portion 57 having a protruding portion 52 is provided on the main body portion 28 of the bus bar unit 51, and the terminal unit 53 is attached to the bus bar unit 51 by fitting the protruding portion 52 and the concave portion 54.

[0033] In the bus bar unit 51, the connection terminal 34 is exposed within the recess 54, and there is no resin-coated portion below it. For this reason, as shown in FIG. 7, the terminal unit 53 is attached to the bus bar unit 51 in such a manner that the front end surface 52a of the protrusion 52 of the bus bar unit 51 directly faces or is in close contact with the connection terminal 34. Therefore, also in the bus bar unit 51, the thickness corresponding to the resin-coated portion 69 in FIG. 9 is reduced, and accordingly, the axial dimension of the stator 2 can be reduced, making it possible to shorten the axial length of the motor.

[0034] Also, the recess 54 is, like the recess 39 of the first embodiment, surrounded by wall portions on all four sides, and the protrusion 52 of the bus bar unit 51 is attached thereto with its movement in the radial and circumferential directions restricted. For this reason, the terminal unit 53 is mounted on the terminal unit mounting portion 57 in a state where it is positioned not only in the radial direction but also in the circumferential direction. That is, similar to the first embodiment, the terminal unit 53 is positioned simply by fitting the protrusion 52 into the recess 54, improving the positioning accuracy of the terminal unit 53 and enabling the terminal unit 53 to be accurately arranged in the motor without providing a separate positioning structure.

[0035] Needless to say, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof. For example, the aforementioned motor 1 employs a 10P12S configuration, but the present invention is applicable to, for example, a brushless motor having a 14P12S configuration. Further, when adjacent coils are in the same phase, it is not necessarily required to adopt the winding form of FIG. 3(a), and it is also possible to adopt the winding form as shown in FIG. 3(b). In addition, the present invention is applicable to a brushless motor having a pole-slot configuration in which adjacent coils are not in the same phase, and in that case, the winding form of FIG. 3(a) is not adopted.

Industrial Applicability

[0036] The present invention is applicable not only to motors for electric power steering devices but also to oil pumps, electric braking systems, hybrid vehicles, electric vehicles, and the like. Further, the motor of the present invention is applicable not only to automotive-related applications but also to other electrical machinery and equipment such as home appliances and industrial machines.

Explanation of Signs

[0037] 1 Brushless motor 2 Stator 3 Rotor 4 Motor housing 5a, 5b Bearings 6 Bearing holder plate 7 Bearing holder 8 Bearing fixing part 9 Rotor shaft 11 Rotor core 12 Magnet 13 Magnet cover 14 Magnet holder 15 Sensor magnet 16 Sensor magnet holder 17 Joint 21 Stator core 22 Teeth 23 Stator coil 23a End part 23p, 23q Coils (in-phase) 24 Busbar unit 25 Slot 26 Insulator 27 Jumper wire 28 Body part 28a End part of the body 29 Busbar 29a Power supply terminal 31 Terminal unit 32 Terminal unit mounting part 33 Base part 34 Connection terminal 34a Long terminal piece 34b Short terminal piece 34c Base part 35 Harness 36 Power terminal 37 Power supply terminal 37U, 37V, 37W Power supply terminals 38 Protrusion 38a Tip surface 39 Recess 41 Fitting joint 42 Outer peripheral wall (wall part) 43 Inner peripheral wall (wall part) 44 Side wall (wall part) 45 Side wall (wall part) 51 Bus bar unit 52 Protrusion 52a Tip surface 53 Terminal unit 54 Recess 55 Side wall (wall part) 56 Side wall (wall part) 57 Terminal unit mounting part 61 Bus bar unit 62 Terminal unit 63 Power supply terminal 64 Bus bar 65 Connection terminal 66 Fitting joint 67 Concave groove 68 Protrusion 69 Resin coating part 71p, 71q Coils 72 Jumper wire 73 Slot S Winding start point F Winding end point Z Region

Claims

1. A bus bar unit arranged on one end side of a stator core, having a main body portion made of synthetic resin and a bus bar made of metal that is integrated with the main body portion and electrically connected to a stator coil, and a terminal unit having a connection terminal electrically connected to an external power source is attached to the main body portion, wherein the main body portion includes a recess in which a part of the bus bar is disposed in an exposed state, the terminal unit includes a protrusion that is disposed to face the exposed bus bar by fitting with the recess, and is characterized by the bus bar unit.

2. A bus bar unit arranged on one end side of a stator core, having a main body portion made of synthetic resin and a bus bar made of metal that is integrated with the main body portion and electrically connected to a stator coil, and a terminal unit having a connection terminal electrically connected to an external power source is attached to the main body portion, wherein the terminal unit includes a recess in which a part of the connection terminal is disposed in an exposed state, the main body portion includes a protrusion that is disposed to face the exposed bus bar by fitting with the recess, and is characterized by the bus bar unit.

3. In the bus bar unit according to claim 1 or 2, the recess has a wall portion surrounding the radial direction and the circumferential direction of the recess, the protrusion is attached to the recess in a state where movement in the radial direction and the circumferential direction is restricted by the wall portion, and is characterized by the bus bar unit.

Images