Busbar unit and brushless motor

Abstract

In the busbar unit (4), a holder (20) that covers multiple busbars (30) has an annular region (R) on a plane (P) perpendicular to an axis (C). The busbars (30) are arranged within the annular region (R), with the centers of their arcs offset from one another, and portions of each busbar (30) overlap with the other busbars (30) within a predetermined angular range of the annular region (R). Alternatively, the busbar unit (4) of an inner rotor brushless motor (1) includes a holder (20) that is mounted on a stator (3) and multiple busbars (30) that connect the three-phase coils (16) of the stator (3) for each of the same phases. Each busbar (30) extends circumferentially and is covered by the holder (20) at the same axial position. The first portion (31) of each bus bar (30) is located radially inward of the second portion (32) of the bus bar (30) and overlaps with the second portion (32) of another bus bar (30) when viewed in the radial direction.

Description

[Technical Field]

[0001] The present invention relates to a busbar unit and a brushless motor including the busbar unit. [Background technology]

[0002] Conventionally, brushless motors have been known in which the windings of multiple coils provided in a stator are connected using a conductive bus bar. For example, Patent Document 1 discloses a brushless motor equipped with a connection bus bar (bus bar unit) that has multiple conductive plates (bus bars) that connect the windings of the multiple coils and an insulating member that houses these conductive plates in an axially stacked state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7280070 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in a configuration in which multiple bus bars are stacked in the axial direction, as in the brushless motor of Patent Document 1, it is necessary to secure space inside the motor for arranging the stacked bus bars, and there is room for improvement in cases where it is desirable to avoid increasing the motor size in the axial direction. Note that the above-mentioned issue can arise when multiple bus bars are provided in a bus bar unit, and is not limited to cases in which the components connected by the bus bars are motor coils, and is not limited to cases in which the device in which the bus bar unit is provided is a motor.

[0005] The present invention has been devised in view of the above-mentioned problems, and has as one object to provide a busbar unit and a brushless motor including the busbar unit that can suppress an increase in the size of a device to which the busbar unit is attached. However, the present invention is not limited to this object. Another object of the present invention is to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the below-described detailed description of the invention. [Means for solving the problem]

[0006] The disclosed busbar unit and brushless motor can be realized as the following disclosed aspects (application examples), which solve at least part of the above-mentioned problems.

[0007] Aspect 1. The disclosed busbar unit includes a plurality of arc-shaped busbars and a holder that covers the plurality of busbars and is annular about an axis. The holder has an annular region having a predetermined radial width centered on the axis in a plane perpendicular to the axis, and each of the busbars is disposed within the annular region, with the centers of the arcs of the busbars offset from one another, and at least a portion of each of the busbars overlaps with the other busbars within a predetermined angular range of the annular region.

[0008] Aspect 2. Another disclosed busbar unit is a busbar unit for an inner rotor brushless motor including an annular stator and a rotor located radially inward of the stator, the busbar unit including a resin holder placed on a predetermined axial side of the stator in the axial direction of the stator, and a plurality of conductive busbars connecting three-phase coils provided on the stator for each of the same phases. Each of the busbars extends along the circumferential direction of the stator and is covered by the holder at the same position in the axial direction, a first portion on one end side in the circumferential direction is located inward relative to a second portion on the other end side in the circumferential direction, The bus bar has a first joint provided in the first portion to which a winding that forms one of the two coils connected by the bus bar is joined, and a second joint provided in the second portion to which a winding that forms the other of the two coils is joined. The first portion of each of the bus bars and the second portion of any of the bus bars other than the bus bar overlap each other when viewed from the radial direction. The holder has a first notch recessed from the inside to expose the first joint portion in the predetermined axial direction, and a second notch recessed from the outside in the radial direction to expose the second joint portion in the predetermined axial direction. .

[0009] Aspect 3. The disclosed brushless motor includes a busbar unit including the busbar unit of Aspect 2 above, the stator on which the busbar unit is mounted, and the rotor that rotates integrally with the shaft on the inner side of the stator. Aspect 4. Another disclosed brushless motor includes a busbar unit including the busbar unit of Aspect 1 described above, an annular stator on which the busbar unit is mounted, and a rotor located radially inward of the stator and rotating integrally with a shaft on the inner side of the stator. [Effects of the Invention]

[0010] According to the disclosed invention, it is possible to provide a busbar unit that can suppress an increase in the size of a device in which the busbar unit is installed, and further it is possible to provide a brushless motor that includes this busbar unit. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an exploded perspective view of a brushless motor to which a busbar unit according to an embodiment is applied; [Figure 2] FIG. 2 is a perspective view of a stator included in the brushless motor of FIG. [Figure 3] 3 is a diagram showing a schematic diagram of a wiring method and a connection method of windings that form the coils provided in the stator of FIG. 2. FIG. [Figure 4] FIG. 10 is a perspective view illustrating a portion of a core unit of a stator and the winding wound around that portion, illustrating the characteristics of the starting and ending wires of the winding. [Figure 5] 2 is a perspective view of a first busbar unit and a stator included in the brushless motor of FIG. 1, as viewed from a first axial direction. [Figure 6] 6 is a cross-sectional view of the first busbar unit of FIG. 5 taken along the arrow XX. [Figure 7] 7 is an axial cross-sectional view of the first busbar unit of FIG. 6 taken along a plane P. FIG. [Figure 8] 6 is a perspective view of the first busbar unit of FIG. 5 as viewed from a second axis direction. [Figure 9] 2 is a perspective view of a second busbar unit and a stator included in the brushless motor of FIG. 1, viewed from a second axis direction. DETAILED DESCRIPTION OF THE INVENTION

[0012] A busbar unit and a brushless motor according to an embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude various modifications and applications of techniques not explicitly described in the following embodiments. The configurations of the present embodiments can be modified in various ways without departing from the spirit of the embodiments.

[0013] The busbar unit includes a plurality of arc-shaped busbars and a holder that covers the busbars and is annular around an axis. The holder has an annular region with a predetermined radial width centered on the axis in a plane perpendicular to the axis. Each busbar is arranged within the annular region of the holder, with the centers of its arcs offset from one another, and at least a portion of each busbar overlaps with the other busbars within a predetermined angular range within the annular region. This configuration allows the busbars to be arranged without overlapping in the axial direction (axial direction), thereby minimizing the increase in size (particularly the axial size) of the device in which the busbar unit is installed. The busbar unit described in detail below is applied to a brushless motor as an example, but the application of the busbar unit is not limited to motors and may also be applied to various electrical equipment such as distribution boards, storage batteries, and generators.

[0014] Alternatively, the busbar unit may be applied to an inner rotor brushless motor. In this case, the busbar unit includes a resin holder mounted on a predetermined axial side of a stator of the brushless motor and multiple conductive busbars connecting three-phase coils of the stator for each phase. Each busbar extends circumferentially and is covered by the holder at the same axial position relative to the holder. A first portion of each busbar at one circumferential end is located radially inward relative to a second portion of the other circumferential end. Furthermore, the first portion of each busbar overlaps with the second portion of any busbar other than the busbar when viewed radially. This configuration also allows multiple busbars to be arranged without overlapping in the axial direction, thereby minimizing the size (especially the axial size) of the brushless motor in which the busbar unit is installed. In addition, the first and second portions of each busbar can be extended close to the coils connected by the busbar, thereby preventing the windings of the coils connected by the busbar from becoming complicated.

[0015] [1. Configuration] [1-1. Overall structure] FIG. 1 is an exploded perspective view of a brushless motor 1 (hereinafter also referred to as "motor 1") to which a busbar unit according to this embodiment is applied. The brushless motor 1 according to this embodiment is an inner rotor type brushless motor, and as shown in FIG. 1, includes a rotor 2 that rotates integrally with a shaft 1s, a stator 3, and busbar units 4 and 5. The motor 1 is configured such that the rotor 2, stator 3, and busbar units 4 and 5 are housed in a cylindrical housing 6 with a bottom. An end bell 7 serving as a cover member may be combined with the opening side (left side in the figure) of the housing 6.

[0016] Hereinafter, the extending direction of the shaft 1s (the direction of the axis C of the shaft 1s) will be referred to as the axial direction. Of the axial directions, the direction in which the bottom of the housing 6 is located relative to the opening of the housing 6 (the right side in FIG. 1) will be referred to as the first axial direction Da1 (predetermined axial direction), and the direction opposite to the first axial direction Da1 will be referred to as the second axial direction Da2. Directions perpendicular to the axial direction, away from the axis C and toward the axis C, will be referred to as the radial direction. Of the radial directions, the direction away from the axis C will be referred to as the radially outer side (outward), and the direction toward the axis C will be referred to as the radially inner side (inward). A direction perpendicular to the axial direction and circumferential around the axis C will be referred to as the circumferential direction. Of the circumferential directions, the clockwise direction as viewed from the first axial direction Da1 side will be referred to as the first circumferential direction Dc1, and the direction opposite to the first circumferential direction Dc1 (counterclockwise direction) will be referred to as the second circumferential direction Dc2.

[0017] As shown in FIG. 1 , the motor 1 illustrated here includes two busbar units 4 and 5 arranged to sandwich a stator 3 in the axial direction. Hereinafter, the busbar unit 4 located on the first axial direction Da1 side of the stator 3 will be referred to as the first busbar unit 4, and the busbar unit 5 located on the second axial direction Da2 side of the stator 3 will be referred to as the second busbar unit 5. The first busbar unit 4, the stator 3, and the second busbar unit 5 are arranged in this order from the first axial direction Da1 to the second axial direction Da2 and are housed in a housing 6. The rotor 2 and the shaft 1s are inserted radially inside the stator 3 and the two busbar units 4 and 5. The busbar unit according to this embodiment is provided (applied) as the first busbar unit 4.

[0018] [1-2. Rotor] The rotor 2 includes, for example, a rotor core that rotates integrally with the shaft 1s and multiple magnets embedded in the rotor core. The shaft 1s is a rotating shaft that supports the rotor 2 and also functions as an output shaft that extracts the output (mechanical energy) of the motor 1 to the outside. The shaft 1s is rotatably supported by the bottom of the housing 6 and an end bell 7, for example, via two bearings 8 that sandwich the rotor core in the axial direction.

[0019] [1-3. Stator] The stator 3 is an annular component having a space radially inside where the rotor 2 is disposed, and is disposed concentrically with the axis C. Therefore, the axial direction, radial direction, and circumferential direction of the axis C described above can also be expressed as the axial direction, radial direction, and circumferential direction of the stator 3, respectively. The stator 3 of this embodiment has an outer shape that is annular (cylindrical), but the shape of the stator 3 is not limited to this.

[0020] 2, the stator 3 includes a substantially cylindrical core unit 11 and a plurality of coils 16. The core unit 11 is provided as an insert-molded product in which a stator core 11c, which is made up of a plurality of stacked steel plates of the same shape, is molded with a resin that serves as an insulator 11i, and is fixed inside the housing 6.

[0021] The core unit 11 has a cylindrical outer peripheral wall 12, a plurality of teeth 13 protruding radially inward from the inner peripheral surface of the outer peripheral wall 12, and an arc-shaped inner peripheral wall 14 extending circumferentially radially inward of each tooth 13. The teeth 13 are spaced apart at equal intervals in the circumferential direction. Slots 15, the same number as the number of teeth 13, are formed between the teeth 13. The coils 16 are formed by winding a wire W around each of the teeth 13, and the same number as the number of teeth 13 are provided.

[0022] In the core unit 11, the insulators 11i need only insulate the stator core 11c from the coils 16, and do not necessarily cover the entire outer surface of the stator core 11c. For example, in the outer peripheral wall 12, the insulators 11i do not need to cover the outer peripheral surface of the stator core 11c. As shown in the figure, the outer peripheral surface of the stator core 11c may be provided so as to be located radially outward of the outer peripheral surfaces of the insulators 11i provided on both axial sides of the stator core 11c. In other words, the outer peripheral surface of the outer peripheral wall 12 may have steps formed by the stator core 11c and the insulators 11i on both axial sides. The steps can be used to mount a holder 20 (described later) of the first busbar unit 4 on the stator 3.

[0023] 2 and 3, the stator 3 of this embodiment is provided with twelve each of the teeth 13, slots 15, and coils 16. The stator 3 is provided with four each of U-phase coils 16u, V-phase coils 16v, and W-phase coils 16w as the twelve coils 16. A U-phase current is supplied to the U-phase coils 16u, a V-phase current is supplied to the V-phase coils 16v, and a W-phase current is supplied to the W-phase coils 16w.

[0024] 2, only two circumferentially adjacent teeth 13 out of the twelve teeth 13 are shown by dashed lines. Also, only one slot 15 formed between the two illustrated teeth 13 out of the twelve slots 15 is labeled with a reference numeral. In FIG. 3, only some of the twelve teeth 13 and twelve slots 15 are labeled with reference numerals.

[0025] As shown in FIG. 2 , for example, stator 3 has two sets of U-phase coils 16u, two V-phase coils 16v, and two W-phase coils 16w arranged side by side in the circumferential direction. That is, of the four U-phase coils 16u, two U-phase coils 16u are arranged adjacent to each other in the circumferential direction, and two V-phase coils 16v are arranged adjacent to each other in the second circumferential direction Dc2 of the two U-phase coils 16u. Furthermore, two W-phase coils 16w are arranged adjacent to each other in the circumferential direction, and adjacent to each of the two V-phase coils 16v on the second circumferential direction Dc2, and the remaining two U-phase coils 16u of the four U-phase coils 16u are arranged adjacent to each other in the circumferential direction, and adjacent to each of the two W-phase coils 16w on the second circumferential direction Dc2. The remaining two V-phase coils 16v are arranged adjacent to each other in the second circumferential direction Dc2 of the remaining two U-phase coils 16u, and the remaining two W-phase coils 16w are arranged adjacent to each of the remaining two U-phase coils 16u on the second circumferential direction Dc2.

[0026] Hereinafter, two adjacent coils 16 of the same phase are collectively referred to as a coil group 17. In other words, the stator 3 having twelve coils 16 has two each of U-phase coil group 17u, V-phase coil group 17v, and W-phase coil group 17w. In other words, the arrangement of the coils 16 described above can be expressed as U-phase coil group 17u, V-phase coil group 17v, and W-phase coil group 17w being arranged in this order in the circumferential direction on the stator 3, with the two coil groups 17 of each phase being arranged opposite each other across the axis C.

[0027] In this embodiment, as shown in Fig. 3, each coil group 17 is formed by a single continuous winding W. That is, six windings W are provided on the stator 3, and each winding W is wound around two circumferentially adjacent teeth 13 to form each coil group 17. More specifically, the winding W that forms each coil group 17 is wound around one of two circumferentially adjacent teeth 13, and then, without being cut, is wound around the other of the two teeth 13. As shown in the figure, the windings W that form each coil group 17 may be arranged (wired) so that the winding direction around one tooth 13 is opposite to the winding direction around the other tooth 13.

[0028] One of the start wire Ws and the end wire Wf of each winding W is drawn out toward the first axial direction Da1, and the other is drawn out toward the second axial direction Da2. In this embodiment, as shown in Fig. 3 , all of the start wires Ws of the six winding wires W are drawn out toward the second axial direction Da2, and all of the end wires Wf of the six winding wires W are drawn out toward the first axial direction Da1. The six start wires Ws drawn out toward the second axial direction Da2 are joined to a busbar 50 (described later) of the second busbar unit 5, and the six end wires Wf drawn out toward the first axial direction Da1 are joined to a busbar 30 (described later) of the first busbar unit 4.

[0029] Of the six start wires Ws drawn out toward the second axial direction Da2, the start wires Ws of the windings W that form adjacent coil groups 17 may be drawn out from the same (common) slot 15. In this embodiment, two start wires Ws are drawn out from each of three slots 15 that are positioned every third circumferentially. Similarly, of the six end wires Wf drawn out toward the first axial direction Da1, two end wires Wf of the windings W that form adjacent coil groups 17 may be drawn out from the same slot 15. In this embodiment, two end wires Wf are drawn out from each of three slots 15 that are positioned every third circumferentially. The start wires Ws and end wires Wf of each winding W may be drawn out from different slots 15 as shown in FIG. 3 or may be drawn out from the same slot 15.

[0030] Note that the initial wire Ws here refers to the portion of the winding W (conductor) that forms each coil group 17 where the winding begins, and the final wire Wf refers to the portion of the winding W (conductor) that forms each coil group 17 where the winding ends. Electricity supplied to each coil group 17 can flow from the initial wire Ws to the final wire Wf, or from the final wire Wf to the initial wire Ws. For this reason, the initial wire Ws and the final wire Wf are defined regardless of the direction of flow of electricity supplied to each coil group 17.

[0031] 4 is a perspective view showing a portion of the core unit 11 as an example for explaining the characteristics of the starting wire Ws and the ending wire Wf of the winding W, and the winding W wound around the portion. In FIG. 4, the core unit 11 is divided into twelve parts in the circumferential direction, and only one of the twelve divided cores 11n is shown as an example of the portion of the core unit 11. The core unit 11 may be configured by combining a plurality of divided cores 11n divided at equal intervals in the circumferential direction in this manner.

[0032] As described above, in the stator 3 of this embodiment, one winding W is wound continuously around two adjacent teeth 13 to form one coil group 17 consisting of two coils 16 of the same phase. However, Fig. 4 illustrates a case in which one winding W is wound around only one split core 11n (one tooth) to form one coil 16. In this way, the stator 3 may be provided with the same number of windings W as the number of teeth 13.

[0033] As shown in FIG. 4, the initial wire Ws of the winding W is constrained and fixed by the connecting wire Wc, which connects the initial wire Ws and the final wire Wf, and is wound around the teeth. Because the initial wire Ws of the winding W forming each coil group 17 is fixed in this manner, the radial position of the initial wire Ws for each coil group 17 is less likely to vary (there is little play). On the other hand, the final wire Wf, which forms the end of the winding of the winding W, is not constrained by the connecting wire Wc, and therefore has the characteristic of being freely pulled out radially inwardly toward the first axial direction Da1 or outwardly toward the first axial direction Da1. Due to these characteristics, the initial wire Ws can be referred to as the fixed end of the winding W, and the final wire Wf can be referred to as the free end of the winding W.

[0034] [1-4. First busbar unit] The first busbar unit 4 is a component mounted on the first axial direction Da1 side of the stator 3 and connects the three-phase coils 16 for each phase, and includes a resin holder 20 and a plurality of busbars 30, as shown in FIG. 5 . Each busbar 30 is a conductive member that connects the three-phase coils 16 for each phase, and is covered (embedded) in the holder 20. That is, the first busbar unit 4 is provided as an assembly of the plurality of busbars 30 with the resin holder 20, or as an insert-molded product molded with the resin holder 20.

[0035] In the present embodiment, the terminal wires Wf of the two U-phase coil groups 17u, the terminal wires Wf of the two V-phase coil groups 17v, and the terminal wires Wf of the two W-phase coil groups 17w are drawn out in the first axial direction Da1. For this reason, the first busbar unit 4 is provided with three busbars 30, as shown in Figures 3 and 5 : a U-phase busbar 30u that connects the terminal wires Wf of the two U-phase coil groups 17u together, a V-phase busbar 30v that connects the terminal wires Wf of the two V-phase coil groups 17v together, and a W-phase busbar 30w that connects the terminal wires Wf of the two W-phase coil groups 17w together.

[0036] The holder 20 is annular about its axis. In this embodiment, as shown in Fig. 5, the holder 20 is disposed so that its axis coincides with the axis C of the motor 1 (shaft 1s), and is annular in shape surrounding the axis C as viewed in the axial direction. As shown in Figs. 5 and 6, the holder 20 may be provided with a main body 21 that covers the three bus bars 30 and is expanded in a direction perpendicular to the axis C to form an annular shape as viewed in the axial direction and a flat plate shape as viewed in the radial direction.

[0037] As shown in FIG. 6 , the three bus bars 30 are arranged on a plane P that overlaps with the main body 21 in the axial direction. On the plane P, the three bus bars 30 are arranged within an annular region R (a region indicated by light and dark dots in FIG. 7 ) having a predetermined radial width H that is approximately equal to the radial width of the main body 21 (holder 20), as shown in FIG. 7 . Note that FIG. 7 is an axial cross-sectional view of the first bus bar unit 4 cut at the plane P as seen from the first axial direction Da1 side, and for convenience, hatching indicating the cross sections of the holder 20 and the bus bars 30 is omitted in FIG. 7 . In other words, the holder 20 has an annular region R having a predetermined radial width H centered on the axis C on the plane P perpendicular to the axis C, and each of the multiple bus bars 30 is arranged within the annular region R.

[0038] All three bus bars 30 are arc-shaped when viewed in the axial direction. Each bus bar 30 may be, for example, flat and plate-shaped with a uniform axial thickness when viewed in the radial direction as shown in Fig. 6, or may be long and plate-shaped with an arc when viewed in the axial direction as shown in Fig. 7. Each bus bar 30 has the same radii of curvature ru, rv, and rw from the arc centers Cu, Cv, and Cw of each bus bar 30, the same arc lengths based on the arc centers Cu, Cv, and Cw of each bus bar 30, and the same plate thickness. The bus bars 30 may be arranged to have three-fold rotational symmetry about the axis C.

[0039] Hereinafter, the center of the arc of U-phase busbar 30u will be referred to as the U-phase busbar center Cu, the center of V-phase busbar 30v will be referred to as the V-phase busbar center Cv, and the center of W-phase busbar 30w will be referred to as the W-phase busbar center Cw. The U-phase busbar center Cu, V-phase busbar center Cv, and W-phase busbar center Cw are offset from one another. In this embodiment, these busbar centers Cu, Cv, and Cw are the same distance from axis C but are spaced apart from one another at equal intervals around axis C. Because each busbar center Cu, Cv, and Cw is offset from axis C in this way, it can be said that each busbar 30u, 30v, and 30w is eccentric with respect to axis C.

[0040] Each busbar 30 is disposed so that a portion of it radially overlaps (is adjacent to) another busbar 30 within a range of a predetermined angle α (predetermined angle range) around the axis C in the annular region R. Hereinafter, a partially annular (approximately trapezoidal) region of the annular region R at the predetermined angle α (region indicated by dark dots in FIG. 7 ) where each busbar 30 radially overlaps with another busbar 30 is referred to as a predetermined angle region Rα. The predetermined angle α defining the predetermined angle region Rα is not particularly limited as long as it is at least smaller than the central angle of the arc of each busbar 30, but is preferably set to an angle obtained by dividing 360° by the number of slots 15 in the stator 3 (here, 30°, obtained by dividing 360° by 12).

[0041] In this embodiment, both circumferential portions of each busbar 30 are defined as the above-mentioned portions, and each of the circumferential portions of each busbar 30 is radially overlapped with each of the other busbars 30 within a predetermined angle region Rα. Specifically, a portion of one of the three busbars 30 (e.g., the U-phase busbar 30u) on the first circumferential direction Dc1 side is radially overlapped with a portion of one of the remaining two busbars 30 (e.g., the V-phase busbar 30v) on the second circumferential direction Dc2 side within the predetermined angle region Rα. Furthermore, a portion of the one busbar 30 (e.g., the U-phase busbar 30u) on the second circumferential direction Dc2 side is radially overlapped with a portion of the other of the remaining two busbars 30 (e.g., the W-phase busbar 30w) on the first circumferential direction Dc1 side within the predetermined angle region Rα. Correspondingly, three predetermined angle regions Rα are provided at equal intervals and spaced apart from one another in the circumferential direction within the annular region R.

[0042] Hereinafter, the portion of each busbar 30 on the first circumferential direction Dc1 side will be referred to as the first portion 31, and the portion on the second circumferential direction Dc2 side will be referred to as the second portion 32. The first portion 31 of each busbar 30 (e.g., U-phase busbar 30u) is located radially inward of the second portion 32 of another busbar 30 (e.g., V-phase busbar 30v) that radially overlaps with the first portion 31 within a predetermined angle region Rα. In other words, the three busbars 30 are arranged so that they radially overlap each other within a predetermined angle region Rα in the circumferential direction, and the first portions 31 and the second portions 32 are staggered.

[0043] As described above, this arrangement is possible because the busbar centers Cu, Cv, and Cw of the three busbars 30 are offset from one another. This also makes it possible for the first busbar unit 4 to have the three busbars 30 arranged on the same plane P without overlapping in the axial direction. This makes it possible to reduce the axial thickness of the portion of the holder 20 (main body portion 21) that covers these busbars 30, thereby suppressing an increase in the axial size of the motor 1.

[0044] The configuration of the first busbar unit 4 will be described in detail below in different terms from the above description.

[0045] In the first busbar unit 4, the three busbars 30 do not overlap one another when viewed in the axial direction, as shown in Fig. 5, and are arranged at the same axial position relative to the holder 20, i.e., on the same plane P, as shown in Fig. 6. As shown in Fig. 5, each busbar 30 extends along the circumferential direction, and is arranged such that a first portion 31 on the first circumferential direction Dc1 side (one end side) is located radially inward of a second portion 32 on the second circumferential direction Dc2 side (the other end side). Note that "extending along" in this embodiment does not necessarily mean extending in a direction that coincides with (is parallel to) a reference direction (e.g., the circumferential direction), but also includes extending in a direction that is inclined with respect to the reference direction.

[0046] The first portion 31 of each busbar 30 (e.g., the U-phase busbar 30u) and the second portion 32 of any busbar 30 other than the busbar 30 (e.g., the V-phase busbar 30v) are arranged to overlap in the radial direction. That is, the first portion 31 of each busbar 30 is arranged to overlap in the radial direction with the second portion 32 of another busbar 30 that connects the coil group 17 of a phase other than the coil group 17 of the phase to which the busbar 30 is connected (hereinafter also referred to as the "corresponding phase"). Note that "overlapping in the radial direction" is synonymous with being located on a radial line passing through the axis C. That is, the busbars 30 are arranged such that when a radius passing through the first portion 31 of a certain busbar 30 is drawn from the axis C, the second portion 32 of the other busbar 30 is located on that radial line.

[0047] As a result, as shown in FIG. 3 , the first portion 31 and the second portion 32 of each busbar 30 of each phase (e.g., the U-phase busbar 30u) can be extended to the vicinity of each of the two coil groups 17 of the corresponding phase (e.g., the U-phase coil group 17u) without stacking the three busbars 30 in the axial direction. This allows the first busbar unit 4 having three busbars 30 to be arranged in a smaller axial space than in a conventional busbar unit in which multiple busbars are stacked in the axial direction, thereby suppressing an increase in the axial size of the motor 1. Furthermore, because the distance between each busbar 30 of each phase and the coil group 17 of the corresponding phase can be shortened, the end wire Wf (winding W) drawn from the coil group 17 of the corresponding phase can be joined to the busbar 30 of each phase without having to be routed in a complex manner.

[0048] 3, the first portion 31 and the second portion 32 of the busbar 30 of each phase may be arranged to overlap in the axial direction with the slot 15 through which the end wires Wf of the coil group 17 of the corresponding phase are drawn. In the present embodiment, as described above, the end wires Wf of the windings W that form the circumferentially adjacent coil groups 17 of different phases are drawn from each of three slots 15 that are positioned every third circumferentially. Therefore, the first portion 31 of the busbar 30 (e.g., the U-phase busbar 30u) to which one of the end wires Wf of the circumferentially adjacent coil groups 17 of different phases is joined, and the second portion 32 of the busbar 30 (e.g., the V-phase busbar 30v) to which the other of these end wires Wf is joined are arranged to overlap in the axial direction with the common slot 15, and the first busbar unit 4 is provided with three locations where the first portion 31 and the second portion 32 are adjacent in the radial direction.

[0049] The length L (see FIG. 7 ) of circumferential overlap between the first portion 31 of each busbar 30 (e.g., U-phase busbar 30u) and the second portion 32 of any busbar 30 other than the busbar 30 (e.g., V-phase busbar 30v) is preferably approximately equal to the length of a sector arc having a central angle obtained by dividing 360° by the number of slots 15 in the stator 3. Here, since twelve slots 15 are provided, the overlap length L between the first portion 31 and the second portion 32 is approximately equal to the length of a sector arc having a central angle of 30°, obtained by dividing 360° by 12.

[0050] In this embodiment, the first busbar unit 4 is mounted on the stator 3 so that each of the three predetermined angle regions Rα overlaps with each of the three slots 15 that are positioned every third in the circumferential direction, thereby realizing the above-described positional relationship of the first portion 31 and the second portion 32 of each busbar 30 with respect to the slots 15 and the relationship of the overlap length L between the first portion 31 and the second portion 32. In the first busbar unit 4, the first portion 31 and the second portion 32 of each busbar 30 are thus arranged to overlap in the axial direction with the slots 15 from which the end wire Wf of the coil group 17 of the corresponding phase is drawn. This allows the end wire Wf drawn from the coil group 17 of each phase to be routed to the busbar 30 of the corresponding phase without having to be routed in the circumferential direction, thereby further preventing the wiring of the end wire Wf from becoming complicated.

[0051] 3 , of the two in-phase coil groups 17 connected to each busbar 30, the end wire Wf of the coil group 17 (one of the two coils) located on the first circumferential direction Dc1 side of the busbar 30 is joined to a first portion 31 of the busbar 30. Furthermore, of the two in-phase coil groups 17 connected to each busbar 30, the end wire Wf of the coil group 17 (the other of the two coils) located on the second circumferential direction Dc2 side of the busbar 30 is joined to a second portion 32 of the busbar 30.

[0052] Hereinafter, a portion of the first portion 31 of each busbar 30 to which the winding W of the coil group 17 of the corresponding phase located on the first circumferential direction Dc1 side of the busbar 30 is joined will be referred to as a first joint portion 33. Further, a portion of the second portion 32 of each busbar 30 to which the winding W of the coil group 17 of the corresponding phase located on the second circumferential direction Dc2 side of the busbar 30 is joined will be referred to as a second joint portion 34.

[0053] 5, the first bonding portion 33 may be provided at a position in the first portion 31 excluding a first end portion 35 on the first circumferential direction Dc1 side. Similarly, the second bonding portion 34 may be provided at a position in the second portion 32 excluding a second end portion 36 on the second circumferential direction Dc2 side. Grooves 37 may be cut from the radially inner side of the first bonding portion 33 and the radially outer side of the second bonding portion 34, respectively, for catching the end wire Wf to be bonded to these bonding portions 33, 34.

[0054] In a region (predetermined angle region Rα) where the first portion 31 and the second portion 32 of two bus bars 30 overlap as viewed in the radial direction, the first joint portion 33 and the second joint portion 34 may be provided so that they partially overlap each other in the circumferential direction as viewed in the radial direction, as shown in Fig. 5. In this region, the first portion 31 and the second portion 32 do not have to overlap each other over the entire circumferential direction as viewed in the radial direction. In addition, in this region, the circumferential positions of the first joint portion 33 and the second joint portion 34 may coincide with each other (completely overlap).

[0055] As described above, the holder 20 is a resin member that covers the busbar 30, and is placed on the stator 3. In this embodiment, the holder 20 has an annular main body 21, and an outer wall 22 and an inner wall 23 that stand upright from the main body 21 in the second axial direction Da2.

[0056] Main body 21 is a resin member that covers each bus bar 30 and has, for example, an annular (donut-shaped) shape when viewed axially and a flat plate shape when viewed radially as shown in Fig. 6. The axial thickness of main body 21 is preferably set to be slightly larger than the axial thickness of each bus bar 30, so that it can cover the three bus bars 30 from both sides in the axial direction.

[0057] 5, the main body 21 may be provided with a first notch 24 that exposes the first joint portion 33 and a second notch 25 that exposes the second joint portion 34. In this embodiment, three first notches 24 and three second notches 25 are provided in correspondence to the fact that three bus bars 30 each having a first joint portion 33 and a second joint portion 34 are provided.

[0058] The first notch 24 is recessed into the main body portion 21 from the radially inner side and forms a space that exposes the first joint portion 33 in the first axial direction Da1. The first notch 24 preferably exposes only the first joint portion 33 of the first portion 31 in the first axial direction Da1. That is, the first notch 24 is provided so that portions of the first portion 31 adjacent to both circumferential sides of the first joint portion 33 are not exposed from the main body portion 21. As shown in FIGS. 6 and 8 , the first notch 24 may be provided to penetrate the main body portion 21 in the axial direction, or may be provided so as to leave a portion of the main body portion 21 closer to the second axial direction Da2 than the first joint portion 33. Note that the first notch 24 also exposes the first joint portion 33 radially inward.

[0059] The second notch 25 is recessed into the main body portion 21 from the radially outer side and forms a space that exposes the second joint portion 34 in the first axial direction Da1. Similar to the first notch 24, the second notch 25 preferably exposes only the second joint portion 34 of the second portion 32 in the first axial direction Da1. That is, the second notch 25 is provided so that portions of the second portion 32 adjacent to both circumferential sides of the second joint portion 34 are not exposed from the main body portion 21. Similar to the first notch 24, the second notch 25 may be provided so as to penetrate the main body portion 21 in the axial direction, as shown in FIGS. 5 and 8 , or may be provided so as to leave a portion of the main body portion 21 closer to the second axial direction Da2 than the second joint portion 34. The second notch 25 also exposes the second joint portion 34 radially outward.

[0060] 8, a plurality of (here, three) recesses may be provided between the three second notches 25 in the circumferential direction by recessing the end face of the main body portion 21 on the second axial direction Da2 side. Similarly, a plurality of (here, three) recesses may be provided between the three first notches 24 in the circumferential direction by recessing the end face of the main body portion 21 on the second axial direction Da2 side. When the core unit 11 is composed of a plurality of split cores 11n, the first notches 24 and the second notches 25 and these recesses can be used to temporarily position each split core 11n.

[0061] The outer wall portion 22 is a portion that stands from the outer peripheral edge of the annular main body portion 21 toward the second axial direction Da2. The outer wall portion 22 may have, for example, an arc shape that stands from a position of the main body portion 21 excluding the second notch 25. As shown in FIG. 5 , for example, the outer wall portion 22 surrounds the outer peripheral wall 12 of the core unit 11 from the radial outside and abuts against a step between the insulator 11i and the stator core 11c, so that the holder 20 is placed on the first axial direction Da1 side of the stator 3. By placing the holder 20 directly on the stator core 11c in this manner without using the insulator 11i, variation in the axial position of the busbar 30 relative to the stator 3 due to dimensional errors in the insulator 11i is suppressed.

[0062] As shown in Fig. 8, the inner wall portion 23 is a portion extending from the inner peripheral edge of the annular main body portion 21 toward the second axial direction Da2. The inner wall portion 23 may have, for example, an arc shape extending from a position of the main body portion 21 excluding the first notch 24. As shown in Fig. 5, the inner wall portion 23 may be provided so as to surround the inner peripheral wall 14 of the core unit 11 from the radially inner side when the first busbar unit 4 is assembled to the stator 3. When the core unit 11 is composed of a plurality of split cores 11n, the inner wall portion 23, together with the outer wall portion 22, can be used to temporarily position each split core 11n.

[0063] When assembling the first busbar unit 4 to the stator 3, the end wires Wf of the two in-phase coil groups 17 are respectively drawn out radially inward and radially outward (hooked) before the first busbar unit 4 is placed on the stator 3. More specifically, of the end wires Wf of the two in-phase coil groups 17, the end wire Wf joined to the first joint portion 33 is hooked radially inward, and the end wire Wf joined to the second joint portion 34 is hooked radially outward. Note that Fig. 5 illustrates a state in which the end wires Wf are drawn out radially inward and radially outward, respectively.

[0064] The first busbar unit 4 is then placed on the stator 3 so that the first joint 33 is adjacent to the end wires Wf hooked radially inward and the second joint 34 is adjacent to the end wires Wf hooked radially outward. In this way, in the region where the first portion 31 and the second portion 32 of the two busbars 30 overlap in the radial direction (predetermined angle region Rα), the end wires Wf joined to the first joint 33 and the end wires Wf joined to the second joint 34 are hooked in different directions, allowing these windings W to be wired without entanglement or crossing. This prevents contact between the end wires Wf and simplifies routing of the end wires Wf.

[0065] Furthermore, as described above, the portions of the windings W that form each coil group 17 that are pulled out toward the first axis direction Da1 are all end wires Wf that are free ends, making it easy to hook such windings W.

[0066] After the first busbar unit 4 is placed on the stator 3, the end wires Wf drawn radially inward are folded radially outward in the first axial direction Da1, hooked into the grooves 37 of the adjacent first joint portions 33, and come into contact with the first joint portions 33 from the first axial direction Da1 side. This wiring of the end wires Wf is possible because the first joint portions 33 are exposed in the first axial direction Da1 by the first notches 24. The end wires Wf are then joined to the first joint portions 33 by spot welding, which applies pressure to the end wires Wf and the first joint portions 33 from the first axial direction Da1 side to melt and bond them together.

[0067] After the first busbar unit 4 is placed on the stator 3, the end wire Wf drawn out radially outward is folded radially inward in the first axial direction Da1, hooked into the groove 37 of the adjacent second joint portion 34, and abuts against the second joint portion 34 from the first axial direction Da1 side. Similar to the first joint portion 33, the second joint portion 34 is exposed in the first axial direction Da1 by the second notch 25, making it possible to wire the end wire Wf in this manner. The end wire Wf is then joined to the second joint portion 34 by spot welding, which applies pressure to the end wire Wf and the second joint portion 34 from the first axial direction Da1 side to melt and bond them together.

[0068] In this way, by joining each end wire Wf to each joint portion 33, 34 by spot welding rather than manual soldering, the number of steps required for connecting the end wires Wf is reduced. The joint portions 33, 34, which are pressed toward the second axial direction Da2 during spot welding, are supported by the busbar 30 (portions excluding the joint portions 33, 34) covered by the main body portion 21 of the holder 20 placed on the stator 3. This prevents the joint portions 33, 34 from moving toward the second axial direction Da2 or the busbar 30 from falling off during spot welding. In particular, when the joint portions 33, 34 are provided in portions excluding the first end portion 35 and the second end portion 36 as described above, the portions adjacent to both sides of the joint portions 33, 34 are covered by the main body portion 21, so that each joint portion 33, 34 is supported at both ends. This increases the holding force of the busbar 30 during spot welding, further preventing the busbar 30 from falling off.

[0069] [1-5. Second busbar unit] The second busbar unit 5 is a component placed on the second axial direction Da2 side of the stator 3 and connects the three-phase coils 16 in a delta connection (triangle connection) manner, and as shown in Fig. 9, includes a resin holder 40 and a plurality of busbars 50. The second busbar unit 5 is provided as an assembly of the plurality of busbars 50 with the resin holder 40, or as an insert-molded product molded with the resin holder 40.

[0070] Each busbar 50 is a conductive member that connects two different phase coils 16 among the three-phase coils 16. In the present embodiment, the initial wires Ws of the two U-phase coil groups 17u, the initial wires Ws of the two V-phase coil groups 17v, and the initial wires Ws of the two W-phase coil groups 17w are drawn to the second axial direction Da2 side of the stator 3. Correspondingly, the second busbar unit 5 is provided with three busbars 50: a U-line busbar 50u, a V-line busbar 50v, and a W-line busbar 50w.

[0071] 3, the U-line busbar 50u connects the start wire Ws of one of the two U-phase coil groups 17u to the start wire Ws of one of the two V-phase coil groups 17v. The V-line busbar 50v connects the start wire Ws of the other of the two V-phase coil groups 17v to the start wire Ws of one of the two W-phase coil groups 17w. The W-line busbar 50w connects the start wire Ws of the other of the two U-phase coil groups 17u to the start wire Ws of the other of the two W-phase coil groups 17w.

[0072] 9, each of the three bus bars 50 may have a substrate portion 51 extending in the circumferential direction and covered (embedded) in the holder 40. The substrate portion 51 has, for example, a long plate shape extending in the circumferential direction. The three substrate portions 51 may be provided at the same axial position so as not to overlap one another as viewed in the axial direction, i.e., on the same plane.

[0073] The initial wire Ws of each coil group 17 is joined to a portion of the substrate portion 51. Hereinafter, the portion of the substrate portion 51 of each busbar 50 to which the initial wire Ws is joined is referred to as a joint portion 52. As shown in FIG. 3 , the U-line busbar 50u, the V-line busbar 50v, and the W-line busbar 50w may connect the initial wires Ws of coil groups 17 of different phases that are drawn out from a common slot 15. Correspondingly, each busbar 50 is provided with one joint portion 52, and the joint portion 52 of each busbar 50 may be arranged to axially overlap the slot 15 from which the initial wires Ws connected by that busbar 50 are drawn.

[0074] The three joints 52 may be provided at equal intervals in the circumferential direction and spaced apart from one another so as to overlap with the three slots 15, respectively, in correspondence with the fact that the initial wire Ws of each coil group 17 is drawn out from three slots 15 located every third in the circumferential direction, as shown in Fig. 9. Note that Fig. 9 illustrates a state in which the initial wire Ws is drawn out toward the second axial direction Da2. The three joints 52 may be arranged, for example, so as to be located radially inward of the initial wire Ws when the second busbar unit 5 is mounted on the stator 3.

[0075] Each bus bar 50 may be provided as a terminal electrically connected to an external power supply device (not shown). In this case, each bus bar 50 may further include a terminal portion 53 extending from an end portion of the substrate portion 51 in the extension direction toward the second axis direction Da2 and connected to the external power supply device.

[0076] As described above, holder 40 is a resin member that covers substrate portions 51 of busbars 50, and is placed on stator 3. Holder 40 may be provided with main body portions 41 for covering substrate portions 51 of each busbar 50. When each busbar 50 is provided as a terminal, holder 40 may be provided with protrusions 42 for covering the portions of terminal portions 53 of each busbar 50 on the first axial direction Da1 side.

[0077] The main body 41 has, for example, an annular (donut-shaped) shape when viewed axially and a flat plate shape when viewed radially. The main body 41 may have through holes 43 and notches 44 provided around the joints 52 as part of a configuration that reduces the number of steps required for assembling the second busbar unit 5 to the stator 3 and for connecting the initial wires Ws. Three through holes 43 and three notches 44 may be provided in the main body 41, corresponding to the three joints 52.

[0078] The through hole 43 is a hole that penetrates in the axial direction and through which the starting wire Ws is inserted. The notch 44 is a portion that forms a space by cutting out the main body portion 41 from the second axial direction Da2 side on the radially inner side or radially outer side of the through hole 43 so as to expose the joint portion 52 of the base plate portion 51 in the second axial direction Da2. The notch 44 may be provided adjacent to the radially inner side of the through hole 43 in correspondence with the joint portion 52 being disposed so as to be located radially inner than the starting line Ws.

[0079] The initial wires Ws of the coil groups 17 of different phases connected to each busbar 50 are, for example, drawn out from a common slot 15 and inserted into a common through-hole 43 as shown in FIG. 9 . The portions of the windings W forming each coil group 17 drawn toward the second axis direction Da2 are all fixed ends of the initial wires Ws. As described above, the initial wires Ws have the characteristic that their positions are unlikely to vary among the coil groups 17. Therefore, simply placing the second busbar unit 5 on the stator 3 allows the initial wires Ws to be inserted into the through-holes 43. This eliminates the need for processes to adjust the position of the initial wires Ws or to anchor the initial wires Ws, thereby reducing the number of steps required to assemble the second busbar unit 5 to the stator 3. Furthermore, the initial wires Ws can be drawn out with high reproducibility to positions suitable for joining to the joints 52, i.e., to positions passing through the through-holes 43.

[0080] The starting wire Ws inserted through the through hole 43 is folded radially inward and comes into contact from the second axial direction Da2 side with the joint portion 52 exposed in the second axial direction Da2 by the notch 44. The starting wire Ws coming into contact with the joint portion 52 is joined to the joint portion 52 not by manual soldering, but by spot welding, in which pressure is applied from the second axial direction Da2 to the joint portion 52 and the starting wire Ws to melt and bond them together. This reduces the number of steps required for connecting the starting wire Ws.

[0081] The joint portion 52, which is pressed toward the first axial direction Da1 during spot welding, is supported by the substrate portion 51 covered by the main body portion 41 of the holder 40 placed on the stator 3. This prevents the joint portion 52 from moving toward the first axial direction Da1 and the bus bar 50 from falling off during spot welding. In other words, in this embodiment, the holder 40 placed on the stator 3 is covered with the substrate portion 51, and the notch 44 is provided to expose the joint portion 52 of the substrate portion 51 in the second axial direction Da2, making it possible to join the joint portion 52 and the starting wire Ws by spot welding rather than by manual soldering.

[0082] Furthermore, the portion of the winding W of each coil group 17 that is joined to the joint portion 52 is the starting wire Ws, which is less likely to have variations in its pull-out position, and these starting wires Ws are always pulled out from the through holes 43, improving the reproducibility of the position of the starting wire Ws that is to be spot welded. Therefore, when the joining process of the starting wire Ws is automated and incorporated into the manufacturing process of the motor 1, it is possible to prevent the handling of the starting wire Ws from becoming complicated.

[0083] [2. Actions and Effects] (1) In the first busbar unit 4 described above, the holder 20 has an annular region R having a predetermined radial width H centered on the axis C in a plane P perpendicular to the axis C, and each of the multiple busbars 30 is arranged within the annular region R. The centers of the arcs of the busbars 30 are offset from one another, and at least a portion of each busbar 30 overlaps with the other busbars 30 within a predetermined angular range of the annular region R. This reduces the axial thickness of the portion of the holder 20 that covers the multiple busbars 30 (the main body portion 21 in this embodiment). This reduces the axial space inside the motor 1, thereby preventing the motor from becoming larger.

[0084] (2) In the first busbar unit 4 and motor 1 described above, the three busbars 30 that connect the three-phase coils 16 (coil group 17) provided on the stator 3 for each phase are covered by the holder 20 at the same axial position on the holder 20. This reduces the axial thickness of the portion of the holder 20 where these busbars 30 are covered (the main body portion 21 in this embodiment). This allows for space saving inside the motor 1 in the axial direction, thereby preventing an increase in the motor size.

[0085] Furthermore, in the first busbar unit 4 and motor 1 described above, the first portion 31 of the busbar 30 of each phase is located radially inward of the second portion 32 of the busbar 30, and is arranged to overlap the second portion 32 of the busbar 30 of a different phase as viewed from the radial direction. This allows the first portion 31 and the second portion 32 of the busbar 30 of each phase to be extended close to the coil 16 (coil group 17) of the corresponding phase, and therefore allows the end wires Wf to be joined to the busbar 30 of each phase without requiring complex routing of the end wires Wf (windings W).

[0086] (3) In the first busbar unit 4 described above, the first joint portion 33 of the busbar 30 covered by the holder 20 placed on the stator 3 is exposed in the first axial direction Da1 by the first notch 24. Similarly, the second joint portion 34 of the busbar 30 covered by the holder 20 placed on the stator 3 is exposed in the first axial direction Da1 by the second notch 25. This allows the end wires Wf hooked to the radially inner and outer sides to be spot-welded to the first joint portion 33 and the second joint portion 34 from the first axial direction Da1 side before the first busbar unit 4 is placed on the stator 3. This reduces the number of assembly steps compared to manual soldering.

[0087] (4) Furthermore, in the first busbar unit 4 described above, only the first joint portion 33 of the first portion 31 is exposed in the first axial direction Da1 by the first notch 24, and adjacent portions on both sides of the first joint portion 33 are not exposed but are covered by the holder 20. Also, only the second joint portion 34 of the second portion 32 is exposed in the first axial direction Da1 by the second notch 25, and adjacent portions on both sides of the second joint portion 34 are not exposed but are covered by the holder 20. This allows each joint portion 33, 34 to be supported at both ends, thereby more appropriately joining the end wire Wf to each joint portion 33, 34.

[0088] (5) If the grooves 37 for hooking the end wire Wf are provided on the radially inner side of the first joint portion 33 and the radially outer side of the second joint portion 34, the end wire Wf can be positioned relative to each of the joint portions 33, 34 before joining the end wire Wf to each of the joint portions 33, 34. Therefore, joining of the end wire Wf to each of the joint portions 33, 34 can be more appropriately performed.

[0089] (6) If the portions of the windings W forming each coil group 17 drawn toward the first axial direction Da1 are all free ends of the end wires Wf, it is easy to hook the end wires Wf joined to the first joint portion 33 radially inward and the end wires Wf joined to the second joint portion 34 radially outward. Furthermore, in the region where the first portion 31 and the second portion 32 of two bus bars 30 overlap in the radial direction, if the end wires Wf joined to the first joint portion 33 and the end wires Wf joined to the second joint portion 34 are hooked in different radial directions, these end wires Wf can be wired without entangling or crossing each other. This simplifies the routing of the end wires Wf and prevents the end wires Wf from coming into contact with each other and conducting current.

[0090] (7) If the length L of the circumferential overlap between the first portion 31 of each bus bar 30 and the second portion 32 of another bus bar 30 is approximately equal to the length of a sectorial arc having a central angle equal to 360° divided by the number of slots 15 in the stator 3, then it becomes easier to insulate the bus bars 30 from each other and to prevent the wiring of the terminal wires Wf from becoming too complicated, compared to when the overlap length L between the first portion 31 and the second portion 32 is longer than the length of the arc.

[0091] (8) If the three bus bars 30 provided in the first bus bar unit 4 all have the same shape, the components (bus bars 30) can be standardized, which contributes to reducing the manufacturing cost of the motor 1.

[0092] [3. Other] The above-described configurations of the first busbar unit 4 and motor 1 are merely examples, and the motor 1 is not limited to the above-described configurations. For example, the motor 1 may be configured such that the second busbar unit 5, the stator 3, and the first busbar unit 4 are arranged in this order from the first axial direction Da1 toward the second axial direction Da2. In this case, the "predetermined axial direction" described in the claims is the second axial direction Da2. The first circumferential direction Dc1 and the second circumferential direction Dc2 of the first busbar unit 4 described above are merely examples, and these directions may be reversed.

[0093] The first busbar unit 4 does not have to be an insert-molded product in which multiple busbars 30 are molded in a resin holder 20, but may be a structure in which multiple busbars 30 are assembled inside the resin holder 20 after the resin holder 20 is molded. Similarly, the second busbar unit 5 does not have to be an insert-molded product, but may be a structure in which multiple busbars 50 are assembled inside the resin holder 40 after the resin holder 40 is molded. The end wires Wf of the busbars 30 of the first busbar unit 4 may be joined to the first joint portion 33 or the second joint portion 34 by soldering. Similarly, the end wires Wf of the busbars 50 of the second busbar unit 5 may be joined to the joint portion 52 by soldering.

[0094] The busbar unit provided on the second axial direction Da2 side of the stator 3 does not have to be the second busbar unit 5 that connects the three-phase coils 16 in a delta connection (triangle connection) manner, and may be a busbar unit that connects the three-phase coils 16 in a star connection manner. Note that the motor 1 does not necessarily have to include the second busbar unit 5.

[0095] The winding W does not have to form two adjacently arranged coils 16 of the same phase, but may form, for example, a single coil 16. That is, the number of windings W provided on the stator 3 is not limited to the six mentioned above. The number of coils 16 provided on the stator 3 does not have to be twelve, as long as it is at least a multiple of six.

[0096] Of the windings W forming each coil 16 (coil group 17), the portion drawn out toward the first axial direction Da1 does not have to be the end wire Wf. In other words, the busbar 30 of the first busbar unit 4 does not have to connect the end wires Wf of each coil 16 (coil group 17). Note that the end wires Wf of the windings W forming circumferentially adjacent coils 16 of different phases do not have to be drawn out from the same slot 15.

[0097] The first notch 24 and the second notch 25 provided in the holder 20 of the first busbar unit 4 may be omitted. For example, if the first end 35 of each busbar 30 is positioned (protrudes) radially inward from the holder 20 and functions as the first joint 33, the first notch 24 may be omitted. Similarly, if the second end 36 of each busbar 30 is positioned (protrudes) radially outward from the holder 20 and functions as the second joint 34, the second notch 25 may be omitted.

[0098] In addition, in the above-described embodiment, adjacent portions on both sides of each of the first joint portion 33 and the second joint portion 34 are covered by the holder 20 of the first busbar unit 4 without being exposed, but these adjacent portions may be partially exposed from the holder 20. The grooves 37 provided in each of the joint portions 33, 34 may be omitted. The outer wall portion 22 and the inner wall portion 23 of the holder 20 of the first busbar unit 4 may be omitted. In this case, the main body portion 21 of the holder 20 may be directly placed on the first axial direction Da1 side of the stator 3.

[0099] The holder 20 as a "holder" in claim 1 of the claims need only be annular around its axis and have a shape that can cover multiple bus bars 30, and does not have to be circular. The holder 20 may be non-circular, such as polygonal or elliptical, and the main body 21 of the holder 20 need not be plate-shaped when viewed from the radial direction. The bus bars 30 as a "bus bar" in claim 1 of the claims need only be arc-shaped with centers offset from each other, and do not have to be arc-shaped. For example, if the holder 20 is elliptical, the bus bars 30 may be elliptical arcs arranged within the annular region of the ellipse.

[0100] The holder 20 as a "holder" according to claim 3 of the present invention may have any shape that can at least cover a plurality of bus bars 30, and does not have to be annular. The holder 20 may have, for example, a disk, fan, or rectangle, and the main body 21 of the holder 20 may not be plate-shaped when viewed from the radial direction. The bus bars 30 as a "bus bar" according to claim 3 of the present invention may at least extend along the circumferential direction, and the first portion 31 of each bus bar 30 may be located radially inward relative to the second portion 31, and may not have an arc shape eccentric from the axis C. The bus bars 30 may have, for example, a spiral shape that extends radially outward from the first circumferential direction Dc1 toward the second circumferential direction Dc2.

[0101] The number of bus bars provided in the bus bar unit is not limited to three. Furthermore, the multiple bus bars provided in the bus bar unit do not all need to have the same shape. [Explanation of symbols]

[0102] 1 Motor (brushless motor) 1s shaft 2 rotors 3 Stator 4 First busbar unit (busbar unit) 15 slots 16 coils 16u U phase coil (coil) 16v V-phase coil (coil) 16w W phase coil (coil) 17 Coil group (coil) 17u U phase coil group (coil) 17v V-phase coil group (coil) 17w W phase coil group (coil) 20 Holder 24. All missing 25 Second notch 30 Busbar 30u U-phase busbar (busbar) 30v V-phase busbar (busbar) 30w W-phase busbar (busbar) 31 Part 1 32 Second part 33 First joint 34 Second joint 37 Groove α Predetermined angle C axis Cu U-phase busbar center (arc center) Cv V-phase busbar center (arc center) Cw W-phase busbar center (arc center) Da1 First axis direction (predetermined axis direction) H specified radial width L overlap length (the length of overlap between the first portion of the busbar and the second portion of any busbar other than the busbar in the circumferential direction) P plane R annular region W winding Wf terminal line

Claims

1. a plurality of arc-shaped bus bars; a holder that covers the plurality of bus bars and is annular about the axis line, the holder has an annular region having a predetermined radial width centered on the axis in a plane perpendicular to the axis, Each of the bus bars is disposed within the annular region, and the centers of the arcs of the bus bars are offset from each other; At least a portion of each of the bus bars overlaps with another of the bus bars within a predetermined angular range of the annular region. A busbar unit characterized by:

2. Each of the bus bars has the same shape. The busbar unit according to claim 1 ,

3. A bus bar unit for an inner rotor type brushless motor including an annular stator and a rotor positioned radially inward of the stator, a resin holder placed on a predetermined axial side of the stator in the axial direction of the stator; a plurality of conductive bus bars that connect three-phase coils provided in the stator for each of the same phases, Each of the bus bars comprises: the rotor extends along a circumferential direction of the stator and is covered by the holder at the same position in the axial direction with respect to the holder, a first portion on one end side in the circumferential direction is located inward relative to a second portion on the other end side in the circumferential direction, a first joint portion provided in the first portion, to which a winding that forms one of the two coils connected by the bus bar is joined; a second joint portion provided in the second portion to which a winding forming the other of the two coils is joined, the first portion of each of the bus bars overlaps with the second portion of any of the bus bars other than the bus bar when viewed from the radial direction; The holder has a first notch recessed from the inside to expose the first joint portion in the predetermined axial direction, and a second notch recessed from the outside in the radial direction to expose the second joint portion in the predetermined axial direction. A busbar unit characterized by:

4. The ends of the windings of the two coils are joined to the first joint portion and the second joint portion, respectively. The busbar unit according to claim 3 ,

5. Portions of the first portion adjacent to both sides of the first joint portion in the circumferential direction and portions of the second portion adjacent to both sides of the second joint portion in the circumferential direction are both covered by the holder. The busbar unit according to claim 3 ,

6. A groove into which the winding is hooked is provided on the inner side of the first joint portion and the outer side of the second joint portion. The busbar unit according to claim 3 ,

7. The length of overlap between the first portion of each bus bar and the second portion of any of the bus bars other than the bus bar in the circumferential direction is approximately equal to the length of an arc of a sector having a central angle obtained by dividing 360° by the number of slots of the stator. The busbar unit according to claim 3 ,

8. Each of the bus bars has the same shape. The busbar unit according to claim 3 ,

9. The busbar unit according to claim 3; the stator on which the bus bar unit is mounted; the rotor rotating integrally with the shaft on the inner side of the stator; A brushless motor characterized by:

10. A busbar unit according to claim 1, an annular stator on which the bus bar unit is mounted; a rotor located radially inward of the stator and rotating integrally with the shaft on the inner side of the stator; A brushless motor characterized by:

Images