Busbar unit and brushless motor

Abstract

In a busbar unit (4), a holder (20) covering a plurality of busbars (30) has an annular region (R) on a plane (P) orthogonal to an axis (C). The busbars (30) are disposed in the annular region (R) such that the centers of respective arcs thereof are offset from each other, and a portion of each busbar (30) overlaps another busbar (30) within a prescribed angular range of the annular region (R). Alternatively, a busbar unit (4) of an inner rotor brushless motor (1) comprises: a holder (20) placed on a stator (3); and a plurality of busbars (30) for connecting three-phase coils (16) of the stator (3) for each phase. Each busbar (30) extends along the circumferential direction and is covered by the holder (20) at the same position in the axial direction. A first portion (31) of each busbar (30) is located radially inward of a second portion (32) of the busbar (30) and overlaps the second portion (32) of another busbar (30) when viewed from the radial direction.

Description

Busbar Unit and Brushless Motor

[0001] This case relates to a busbar unit and a brushless motor including the busbar unit.

[0002] Conventionally, in a brushless motor, there is known a configuration in which windings of a plurality of coils provided in a stator are connected using conductive busbars. For example, Patent Document 1 discloses a brushless motor including a connection busbar (busbar unit) having a plurality of conductive plates (busbars here) for connecting windings of a plurality of coils and an insulating member that houses these conductive plates in a stacked state in the axial direction.

[0003] Japanese Patent No. 7280070

[0004] By the way, in a configuration in which a plurality of busbars are stacked in the axial direction as in the brushless motor of Patent Document 1, it is necessary to secure a space inside the motor for arranging the stacked busbars, and there is room for improvement when it is not desired to increase the motor size in the axial direction. Note that the above problems are problems that can occur when a plurality of busbars are provided in the busbar unit, and are not limited to the case where the components connected by these busbars are the coils of the motor, nor are they limited to the case where the device provided with this busbar unit is a motor.

[0005] This case was devised in view of such problems, and one of its purposes is to provide a busbar unit capable of suppressing an increase in the size of a device provided with the busbar unit and a brushless motor including this busbar unit. Note that this is not limited to this purpose, and it is also another purpose of this case to exhibit an operational effect that is not obtained by the conventional technology and is derived from each configuration shown in the mode for carrying out the invention described later.

[0006] The disclosed busbar unit and brushless motor can be realized as the following disclosed modes (application examples) and solve at least some of the above problems.

[0007] Embodiment 1. The disclosed busbar unit comprises a plurality of arc-shaped busbars and an annular holder covering the plurality of busbars and having an annular shape around an axis. 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 busbars is arranged within the annular region, and the centers of the arcs are offset from each other, and at least a portion of each busbar overlaps with the other busbars within a predetermined angular range of the annular region.

[0008] Embodiment 2. Another busbar unit of the Disclosure is a busbar unit for an inner rotor type brushless motor comprising an annular stator and a rotor located radially inward of the stator, comprising a resin holder mounted 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, phase by phase. Each of the busbars extends along the circumferential direction of the stator and is covered by the holder at the same axial position relative to the holder, with a first portion at one end in the circumferential direction located inward of a second portion at the other end in the circumferential direction, and the first portion of each busbar and the second portion of any other busbar overlap when viewed radially.

[0009] Embodiment 3. The disclosed brushless motor comprises a busbar unit including Embodiment 2 above, a stator on which the busbar unit is mounted, and a rotor that rotates integrally with the shaft on the inner side of the stator.

[0010] According to the disclosed invention, it is possible to provide a busbar unit that can suppress an increase in the size of the device on which the busbar unit is provided, and furthermore, it is also possible to provide a brushless motor equipped with this busbar unit.

[0011] Figure 1 is an exploded perspective view of a brushless motor to which the busbar unit according to the embodiment is applied. Figure 2 is a perspective view of the stator of the brushless motor of Figure 1. Figure 3 is a schematic diagram showing the wiring method and connection method of the windings that form the coils provided on the stator of Figure 2. Figure 4 is a perspective view for explaining the characteristics of the start and end wires of the windings, showing a part of the core unit of the stator and the windings wound around that part. Figure 5 is a perspective view of the first busbar unit and stator of the brushless motor of Figure 1, viewed from the first axial direction. Figure 5 is a cross-sectional view of the first busbar unit taken along the line X-X. Figure 6 is an axial cross-sectional view of the first busbar unit cut by a plane P. Figure 5 is a perspective view of the first busbar unit of Figure 5, viewed from the second axial direction. Figure 6 is a perspective view of the second busbar unit and stator of the brushless motor of Figure 1, viewed from the second axial direction.

[0012] The busbar unit and brushless motor as embodiments will be described with reference to the drawings. The embodiments shown below are merely illustrative, and there is no intention to exclude various modifications and applications of technologies not explicitly shown in the embodiments below. Each component of these embodiments can be modified in various ways without departing from their spirit.

[0013] The busbar unit comprises multiple arc-shaped busbars and an annular holder that covers these busbars and is oriented around their axes. 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, and the centers of the arcs are offset from each other, with at least a portion of each busbar overlapping with other busbars within a predetermined angular range of the annular region. This configuration allows multiple busbars to be arranged without overlapping in the axial direction, thus suppressing an increase in the size of the device (especially the axial size) 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 above busbar unit is not limited to motors; it may be applied to various electrical components such as switchboards, batteries, and generators.

[0014] Alternatively, the busbar unit may be applied to an inner rotor type brushless motor. In this case, the busbar unit comprises a resin holder mounted on a predetermined axial side of the stator of the brushless motor, and a plurality of conductive busbars that connect the three-phase coils provided on the stator, one phase at a time. Each busbar extends circumferentially and is covered by the holder at the same axial position relative to the holder, with the first portion at one end circumferentially located radially inward from the second portion at the other end circumferentially. Furthermore, the first portion of each busbar and the second portion of any other busbar overlap when viewed radially. This configuration also allows multiple busbars to be arranged without overlapping in the axial direction, thus suppressing an increase in the size (especially the axial size) of the brushless motor on which the busbar unit is provided. In addition, since the first and second portions of each busbar can be extended close to the coils to which the busbar connects, the routing of the coil windings connected by the busbars is kept from becoming complicated.

[0015] [1. Configuration] [1-1. Overall Configuration] Figure 1 is an exploded perspective view of a brushless motor 1 (hereinafter also referred to as "motor 1") to which the 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 Figure 1, comprises a rotor 2 that rotates integrally with the shaft 1s, a stator 3, and busbar units 4 and 5. The motor 1 is constructed by housing the rotor 2, stator 3, and busbar units 4 and 5 in a bottomed cylindrical housing 6. An end bell 7 as a lid member may be attached to the opening side (left side in the figure) of the housing 6.

[0016] Hereinafter, the direction in which the shaft 1s extends (the direction of the axis C of the shaft 1s) is 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 (right side in Figure 1) is referred to as the first axial direction Da1 (predetermined axial direction), and the direction opposite to the first axial direction Da1 is referred to as the second axial direction Da2. The directions perpendicular to the axial direction that move away from the axis C and the directions toward the axis C are referred to as the radial direction. Of the radial directions, the direction moving away from the axis C is referred to as the radially outward (outward), and the direction toward the axis C is referred to as the radially inward (inward). The directions perpendicular to the axial direction that revolve around the axis C are referred to as the circumferential direction. Of the circumferential directions, the clockwise direction viewed from the first axial direction Da1 side is referred to as the first circumferential direction Dc1, and the direction opposite to the first circumferential direction Dc1 (counterclockwise) is referred to as the second circumferential direction Dc2.

[0017] The motor 1 illustrated here, as shown in Figure 1, comprises two busbar units 4 and 5 arranged to sandwich the 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 housed in the housing 6. The rotor 2 and shaft 1s are inserted radially inside the stator 3 and the two busbar units 4 and 5. In this embodiment, the busbar unit is provided (applied) as the first busbar unit 4.

[0018] [1-2. Rotor] The rotor 2 comprises, for example, a rotor core that rotates integrally with the shaft 1s and a plurality of magnets embedded in the rotor core. The shaft 1s is the 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, for example, two bearings 8 that sandwich the rotor core in the axial direction between the bottom of the housing 6 and the end bell 7.

[0019] [1-3. Stator] The stator 3 is an annular component with a space on its radially inward side where the rotor 2 is positioned, and is concentric with axis C. Therefore, the axial, radial, and circumferential directions of axis C described above can also be expressed as the axial, radial, and circumferential directions of the stator 3. In this embodiment, the stator 3 has an annular (cylindrical) external shape, but the shape of the stator 3 is not limited to this.

[0020] As shown in Figure 2, the stator 3 comprises a substantially cylindrical core unit 11 and a plurality of coils 16. The core unit 11 is provided as an insert molded product, for example, by molding a stator core 11c, which is made of multiple steel plates of the same shape stacked together, with resin that will become an insulator 11i, and is fixed inside the housing 6.

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

[0022] In the core unit 11, the insulator 11i only needs to insulate the stator core 11c from the coil 16, and does not need to cover the entire outer surface of the stator core 11c. For example, in the outer peripheral wall 12, the insulator 11i does not need to cover the outer peripheral surface of the stator core 11c. The outer peripheral surface of the stator core 11c may be positioned radially outward from the outer peripheral surfaces of the insulators 11i provided on both sides in the axial direction, as shown in the figure. In other words, steps formed by the stator core 11c and the insulators 11i may be provided on both sides in the axial direction of the outer peripheral surface of the outer peripheral wall 12. These steps can be used to mount the holder 20 of the first busbar unit 4, which will be described later, onto the stator 3.

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

[0024] In Figure 2, only two teeth 13 that are adjacent in the circumferential direction out of the twelve teeth 13 are shown with dashed lines. Also, out of the twelve slots 15, only one slot 15 formed between the two shown teeth 13 is labeled with a reference numeral. In Figure 3, only parts of the twelve teeth 13 and twelve slots 15 are labeled with reference numerals.

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

[0026] Hereinafter, two adjacent coils 16 of the same phase will be collectively referred to as a coil group 17. The stator 3, which has twelve coils 16, can also be described as having two U-phase coil groups 17u, two V-phase coil groups 17v, and two W-phase coil groups 17w. Furthermore, regarding the arrangement of the coils 16 described above, the stator 3 will be provided with the U-phase coil group 17u, the V-phase coil group 17v, and the W-phase coil group 17w arranged in this order in the circumferential direction, and the two coil groups 17 of each phase will be provided so as to face each other across the axis C.

[0027] In this embodiment, as shown in Figure 3, each coil group 17 is formed by a single continuous winding W. That is, the stator 3 is provided with six windings W, and each coil group 17 is formed by winding each winding W around two teeth 13 adjacent to each other in the circumferential direction. More specifically, the winding W forming each coil group 17 is wound around one of two teeth 13 adjacent to each other in the circumferential direction, and then wound around the other tooth 13 without being cut. The windings W forming each coil group 17 may be routed (wired) such that the winding direction around one tooth 13 is opposite to the winding direction around the other tooth 13, as shown in the figure.

[0028] One of the starting wires Ws and ending wires Wf of each winding W is drawn out in the first axial direction Da1, and the other is drawn out in the second axial direction Da2. In this embodiment, as shown in Figure 3, all six starting wires Ws of the windings W are drawn out in the second axial direction Da2, and all six ending wires Wf of the windings W are drawn out in the first axial direction Da1. The six starting wires Ws drawn out in the second axial direction Da2 are joined to the bus bar 50 of the second bus bar unit 5, which will be described later, and the six ending wires Wf drawn out in the first axial direction Da1 are joined to the bus bar 30 of the first bus bar unit 4, which will be described later.

[0029] Of the six initial wires Ws drawn out in the second axial direction Da2, the initial wires Ws of windings W forming adjacent coil groups 17 may be drawn from the same (common) slot 15. In this embodiment, two initial wires Ws are drawn from each of the three slots 15 located every three in the circumferential direction. Similarly, of the six ending wires Wf drawn out in the first axial direction Da1, the ending wires Wf of windings W forming adjacent coil groups 17 may be drawn from the same slot 15. In this embodiment, two ending wires Wf are drawn from each of the three slots 15 located every three in the circumferential direction. The initial wires Ws and ending wires Wf of each winding W may be drawn from different slots 15, or they may be drawn from the same slot 15, as shown in Figure 3.

[0030] In this context, the starting wire Ws refers to the portion of the winding W (conductor) forming each coil group 17 where the winding begins, and the ending wire Wf refers to the portion of the winding W (conductor) forming each coil group 17 where the winding ends. The electricity supplied to each coil group 17 can flow from the starting wire Ws to the ending wire Wf, or from the ending wire Wf to the starting wire Ws. Therefore, the starting wire Ws and the ending wire Wf are defined independently of the direction of the flow of electricity supplied to each coil group 17.

[0031] Figure 4 is a perspective view showing a part of a core unit 11 and the winding W wound around that part, as an example to illustrate the characteristics of the start wire Ws and end wire Wf of the winding W. In Figure 4, as a part of the core unit 11, the core unit 11 is divided into twelve sections in the circumferential direction, and only one of the twelve divided cores 11n is shown as an example. The core unit 11 may be composed of multiple divided cores 11n that are divided at equal intervals in the circumferential direction in this manner.

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

[0033] As shown in Figure 4, the initial wire Ws of the winding W is constrained and fixed by the connecting wire Wc that connects the initial wire Ws and the final wire Wf, which is wound around the teeth. Since the initial wire Ws of the winding W forming each coil group 17 is fixed in this way, the radial position of the initial wire Ws is less likely to vary (less play) for each coil group 17. On the other hand, the final wire Wf, which is the end of the winding of the winding W, is not constrained by the connecting wire Wc, and therefore has the characteristic of being able to be drawn out toward the first axial direction Da1 and radially inward, or toward the first axial direction Da1 and radially outward. From these characteristics, the initial wire Ws can also be described as the fixed end of the winding W, and the final wire Wf can also be described as the free end of the winding W.

[0034] [1-4. First Busbar Unit] The first busbar unit 4 is mounted on the first axial direction Da1 side of the stator 3 and is a component that connects the three-phase coils 16 according to their phases. As shown in Figure 5, it has a resin holder 20 and a plurality of busbars 30. Each busbar 30 is a conductive member that connects the three-phase coils 16 according to their phases and is covered (embedded) in the holder 20. That is, the first busbar unit 4 is provided as an assembly of a plurality of busbars 30 with the resin holder 20, or as an insert molded product molded by the resin holder 20.

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

[0036] The holder 20 is annular in shape around its axis. In this embodiment, as shown in Figure 5, the holder 20 is provided such that its axis coincides with the axis C of the motor 1 (shaft 1s), and it forms an annular shape surrounding the axis C when viewed from the axial direction. The holder 20 may be provided with a main body portion 21 that covers the three busbars 30, as shown in Figures 5 and 6, which is unfolded in a direction perpendicular to the axis C, forming an annular shape when viewed from the axial direction and a flat plate shape when viewed from the radial direction.

[0037] As shown in Figure 6, the three busbars 30 are arranged on a plane P that overlaps with the main body 21 in the axial direction. On the plane P, as shown in Figure 7, the three busbars 30 are arranged within an annular region R (areas shown in Figure 7 with light and dark dots) having a predetermined radial width H that is approximately equal to the radial width of the main body 21 (holder 20). Note that Figure 7 is an axial cross-sectional view of the first busbar unit 4 cut along the plane P, viewed from the first axial direction Da1 side, and for convenience, hatching showing the cross-sections of the holder 20 and busbars 30 is omitted in Figure 7. In other words, the holder 20 has an annular region R with 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 this annular region R.

[0038] The three busbars 30 are all arc-shaped when viewed from the axial direction. Each busbar 30 may be a flat plate with a uniform thickness in the axial direction when viewed from the radial direction, as shown in Figure 6, or a long plate with an arc shape when viewed from the axial direction, as shown in Figure 7. Each busbar 30 has the same radius of curvature ru, rv, rv from the arc centers Cu, Cv, Cw of each busbar 30, the same arc length with respect to the arc centers Cu, Cv, Cw of each busbar 30, and the same plate thickness, and may be arranged to be three times rotationally symmetric about axis C.

[0039] Hereinafter, the center of the arc of the U-phase busbar 30u will be referred to as the U-phase busbar center Cu, the center of the V-phase busbar 30v will be referred to as the V-phase busbar center Cv, and the center of the W-phase busbar 30w will be referred to as the W-phase busbar center Cw. The U-phase busbar center Cu, the V-phase busbar center Cv, and the W-phase busbar center Cw are offset from each other. In this embodiment, although these busbar centers Cu, Cv, and Cw are the same distance from the axis C, they are spaced apart from each other and spaced equally apart around the axis C. Thus, since each busbar center Cu, Cv, and Cw are offset from the axis C, it can also be said that each busbar 30u, 30v, and 30w are eccentric with respect to the axis C.

[0040] Each busbar 30 is provided such that a portion of it overlaps radially with other busbars 30 (is adjacent to another busbar) within a predetermined angle α (predetermined angle range) centered on the axis C in the annular region R. Hereinafter, the partial annular (approximately trapezoidal) region of the annular region R in which a portion of each busbar 30 overlaps radially with other busbars 30 at a predetermined angle α (the region shown as a dark dot in Figure 7) is referred to as the predetermined angle region Rα. The predetermined angle α that defines the predetermined angle region Rα is not particularly limited, and only needs to be 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 of the stator 3 (here, 30° obtained by dividing 360° by 12).

[0041] In this embodiment, both portions on both sides in the circumferential direction of each bus bar 30 are made to be a part of the above, and each of the portions on both sides in the circumferential direction of each bus bar 30 overlaps radially with each of the other bus bars 30 in a predetermined angular region Rα. More specifically, a portion on the first circumferential direction Dc1 side of one bus bar 30 (for example, the U-phase bus bar 30u) among the three bus bars 30 overlaps radially with a portion on the second circumferential direction Dc2 side of one of the remaining two bus bars 30 (for example, the V-phase bus bar 30v) in a predetermined angular region Rα. Also, a portion on the second circumferential direction Dc2 side of the one bus bar 30 (for example, the U-phase bus bar 30u) overlaps radially with a portion on the first circumferential direction Dc1 side of the other of the remaining two bus bars 30 (for example, the W-phase bus bar 30w) in a predetermined angular region Rα. Corresponding to this, three predetermined angular regions Rα are provided at equal intervals and separated from each other in the circumferential direction in the annular region R.

[0042] Hereinafter, among each bus bar 30, a portion on the first circumferential direction Dc1 side is referred to as a first portion 31, and a portion on the second circumferential direction Dc2 side is referred to as a second portion 32. The first portion 31 of each bus bar 30 (for example, the U-phase bus bar 30u) is located radially inside the second portion 32 of another bus bar 30 (for example, the V-phase bus bar 30v) that overlaps radially with the first portion 31 in a predetermined angular region Rα. That is, the three bus bars 30 overlap radially with each other in a predetermined angular region Rα in the circumferential direction, and the first portion 31 and the second portion 32 are arranged alternately.

[0043] As described above, since the centers Cu, Cv, Cw of the respective bus bars 30 of the three bus bars 30 are displaced, such an arrangement is possible. Also, in the first bus bar unit 4, thereby, it becomes possible to provide the three bus bars 30 on the same plane P without overlapping them in the axial direction. Therefore, since it becomes possible to reduce the axial thickness of the portion (main body portion 21) of the holder 20 that covers these bus bars 30, an increase in the axial size of the motor 1 is suppressed.

[0044] Hereinafter, the configuration of the first bus bar unit 4 will be described in detail in a different way from the above description.

[0045] In the first busbar unit 4, the three busbars 30 are arranged so as shown in Figure 5, they do not overlap each other when viewed from the axial direction, and as shown in Figure 6, they are positioned at the same axial location relative to the holder 20, i.e., on the same plane P. Furthermore, as shown in Figure 5, each busbar 30 extends along the circumferential direction, and the first portion 31 on the first circumferential direction Dc1 side (one end) is positioned radially inward from the second portion 32 on the second circumferential direction Dc2 side (the other end). In this embodiment, "extended along" is not limited to 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 (for example, a U-phase busbar 30u) and the second portion 32 of any other busbar 30 (for example, a V-phase busbar 30v) are arranged to overlap when viewed radially. That is, the first portion 31 of each busbar 30 is arranged to overlap when viewed radially with the second portion 32 of another busbar 30 that connects a coil group 17 of a different phase (hereinafter also referred to as the "corresponding phase") than the coil group 17 of the phase to which the busbar 30 is connected. Note that "overlapping when viewed radially" is synonymous with being located on a radius line passing through axis C. In other words, the arrangement of each busbar 30 is set such that when the radius passing through the first portion 31 of a busbar 30 is drawn from axis C, the second portion 32 of another busbar 30 lies on that radius line.

[0047] As a result, without overlapping the three bus bars 30 in the axial direction, as shown in FIG. 3, each of the first portion 31 and the second portion 32 of the bus bar 30 of each phase (for example, the U-phase bus bar 30u) can be extended to the vicinity of each of the two coil groups 17 of the corresponding phase (for example, the U-phase coil group 17u). Therefore, it becomes possible to arrange the first bus bar unit 4 having the three bus bars 30 in a narrower space in the axial direction than the conventional bus bar unit in which a plurality of bus bars are stacked in the axial direction, and an increase in the axial size of the motor 1 can be suppressed. Further, since the distance between the bus bar 30 of each phase and the coil group 17 of the corresponding phase can be shortened, the end wire Wf (winding W) drawn out from the coil group 17 of the corresponding phase can be joined to the bus bar 30 of each phase without being complicatedly routed around.

[0048] Each of the first portion 31 and the second portion 32 of the bus bar 30 of each phase may be provided so as to overlap axially with the slot 15 from which the end wire Wf of the coil group 17 of the corresponding phase is drawn out, for example, as shown in FIG. 3. In the present embodiment, as described above, the end wire Wf of the winding W forming the coil groups 17 of different phases adjacent in the circumferential direction is drawn out from each of the three slots 15 located every other in the circumferential direction. For this reason, the first portion 31 of the bus bar 30 (for example, the U-phase bus bar 30u) to which one of the end wires Wf of the coil groups 17 of different phases adjacent in the circumferential direction is joined and the second portion 32 of the bus bar 30 (for example, the V-phase bus bar 30v) to which the other of these end wires Wf is joined are provided so as to overlap axially with the common slot 15, and the first bus bar unit 4 is provided with three locations where the first portion 31 and the second portion 32 are adjacent to each other in the radial direction.

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

[0050] In this embodiment, the first busbar unit 4 is mounted on the stator 3 such that each of the three predetermined angular regions Rα described above overlaps with each of the three slots 15 located every three in the circumferential direction. This realizes the arrangement 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, each of the first portion 31 and the second portion 32 of each busbar 30 is provided so that they overlap in the axial direction with the slot 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 each coil group 17 of each phase to be routed to the busbar 30 of the corresponding phase without having to run around in the circumferential direction, thus further suppressing the complexity of the wiring of the end wire Wf.

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

[0052] Hereinafter, the portion of the first part 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 relative to the busbar 30 is joined is referred to as the first joint portion 33. Also, the portion of the second part 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 relative to the busbar 30 is joined is referred to as the second joint portion 34.

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

[0054] Furthermore, in the region where the first portion 31 and the second portion 32 of the two busbars 30 overlap when viewed radially (a predetermined angular region Rα), the first joint portion 33 and the second joint portion 34 may be provided such that a portion of their circumferential direction overlaps with each other when viewed radially, as shown in Figure 5. In the same region, the first portion 31 and the second portion 32 do not have to overlap entirely when viewed radially in the circumferential direction. Also, in the same region, the circumferential position of the first joint portion 33 and the circumferential position of 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 mounted on the stator 3. In this embodiment, the holder 20 has an annular main body portion 21 and an outer wall portion 22 and an inner wall portion 23 that are erected from the main body portion 21 in the second axial direction Da2.

[0056] The main body 21 is a resin member that covers each busbar 30, and for example, it has an annular (donut shape) when viewed from the axial direction and a flat plate shape when viewed from the radial direction, as shown in Figure 6. The axial thickness of the main body 21 is preferably set to be slightly larger than the axial thickness of each busbar 30, so as to be able to cover the three busbars 30 from both sides in the axial direction.

[0057] As shown in Figure 5, the main body portion 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, corresponding to the provision of three busbars 30 having the first joint portion 33 and the second joint portion 34, three first notches 24 and three second notches 25 are provided.

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

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

[0060] Between the three second notches 25 in the circumferential direction, as shown in Figure 8, a plurality of (in this case, three) recesses may be provided by recessing the end face of the main body portion 21 on the second axial direction Da2 side. Similarly, between the three first notches 24 in the circumferential direction, a plurality of (in this case, three) recesses may be provided by recessing the end face of the main body portion 21 on the second axial direction Da2 side. The first notches 24 and the second notches 25 and these recesses can be used for the temporary positioning of each segmented core 11n when the core unit 11 is composed of a plurality of segmented cores 11n.

[0061] The outer wall portion 22 is a part erected from the outer peripheral edge of the annular main body portion 21 toward the second axial direction Da2. The outer wall portion 22 may be, for example, an arc shape erected from a position excluding the second notch 25 of the main body portion 21. The holder 20 is placed on the first axial direction Da1 side of the stator 3 by the outer wall portion 22 surrounding the outer peripheral wall 12 of the core unit 11 from the radially outside and abutting against the step difference between the insulator 11i and the stator core 11c, as shown in Figure 5, for example. By placing the holder 20 directly on the stator core 11c without the insulator 11i in this way, the variation in the axial position of the busbar 30 relative to the stator 3 due to dimensional errors of the insulator 11i is suppressed.

[0062] As shown in Figure 8, the inner wall portion 23 is a portion erected from the inner peripheral edge of the annular main body portion 21 toward the second axial direction Da2. The inner wall portion 23 may be, for example, an arc shape erected from a position excluding the first notch 24 of the main body portion 21. As shown in Figure 5, when the first busbar unit 4 is assembled to the stator 3, 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 inward side. When the core unit 11 is composed of a plurality of segmented cores 11n, the inner wall portion 23 may be used together with the outer wall portion 22 for the temporary positioning of each segmented core 11n.

[0063] When assembling the first busbar unit 4 to the stator 3, the end wires Wf of each of the two in-phase coil groups 17 are pulled out radially inward and radially outward, respectively (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 connected to the first joint 33 is hooked radially inward, and the end wire Wf connected to the second joint 34 is hooked radially outward. Figure 5 illustrates the state in which the end wires Wf are pulled out radially inward and radially outward, respectively.

[0064] Subsequently, the first busbar unit 4 is placed on the stator 3 such that the first joint 33 is adjacent to the end wire Wf hooked radially inward, and the second joint 34 is adjacent to the end wire 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 when viewed radially (a predetermined angular region Rα), the end wire Wf joined to the first joint 33 and the end wire Wf joined to the second joint 34 are hooked in different directions from each other, allowing these windings W to be wired without entanglement or crossing. Therefore, contact between end wires Wf is suppressed and the routing of the end wires Wf is simplified.

[0065] Furthermore, as described above, the portion of the winding W that forms each coil group 17 that is drawn out toward the first axial direction Da1 is a free end wire Wf, so hooking of such windings W can be easily performed.

[0066] After the first busbar unit 4 is placed on the stator 3, the end wire Wf, which is drawn radially inward, is folded toward the first axial direction Da1 and radially outward, and is hooked into the groove 37 of the adjacent first joint 33, and comes into contact with the first joint 33 from the first axial direction Da1 side. Since the first joint 33 is exposed toward the first axial direction Da1 by the first notch 24, such wiring of the end wire Wf becomes possible. The end wire Wf is then joined to the first joint 33 by spot welding, which involves applying pressure from the first axial direction Da1 side to melt and bond the end wire Wf and the first joint 33 together.

[0067] The end wire Wf, which is drawn out radially outward, is folded inward in the first axial direction Da1 and radially after the first busbar unit 4 is placed on the stator 3, and is hooked into the groove 37 of the adjacent second joint 34, so as to come into contact with the second joint 34 from the first axial direction Da1 side. Similar to the first joint 33, the second joint 34 is exposed in the first axial direction Da1 by the second notch 25, which makes it possible to route the end wire Wf in this manner. The end wire Wf is then joined to the second joint 34 by spot welding, which involves applying pressure from the first axial direction Da1 side to melt and bond the end wire Wf and the second joint 34 together.

[0068] In this way, each end wire Wf is joined to each joint 33, 34 by spot welding rather than manual soldering, thereby reducing the man-hours required for connecting the end wires Wf. Each joint 33, 34, which is pressed toward the second axial direction Da2 during spot welding, is supported by the busbar 30 (excluding the joints 33, 34) covered by the main body 21 of the holder 20 mounted on the stator 3. Therefore, movement of each joint 33, 34 toward the second axial direction Da2 and the busbar 30 falling out are suppressed during spot welding. In particular, when each joint 33, 34 is provided in the part excluding the first end 35 and the second end 36 as described above, the parts adjacent to both sides of these joints 33, 34 are covered by the main body 21, so that each joint 33, 34 is supported at both ends. Therefore, the holding force of the busbar 30 during spot welding is increased, and the busbar 30 is further prevented from coming loose.

[0069] [1-5. Second Busbar Unit] The second busbar unit 5 is mounted on the second axial direction Da2 side of the stator 3 and is a component that connects the three-phase coils 16 in a delta connection (triangular connection) manner. As shown in Figure 9, it has 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 by the resin holder 40.

[0070] Each busbar 50 is a conductive member that connects two different phases of the three-phase coil 16. In this embodiment, the starting wires Ws of two U-phase coil groups 17u, two V-phase coil groups 17v, and two W-phase coil groups 17w are drawn out from 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] As shown in Figure 3, the U-line busbar 50u connects the starting wire Ws of one of the two U-phase coil groups 17u to the starting wire Ws of one of the two V-phase coil groups 17v. The V-line busbar 50v connects the starting wire Ws of the other of the two V-phase coil groups 17v to the starting wire Ws of one of the two W-phase coil groups 17w. The W-line busbar 50w connects the starting wire Ws of the other of the two U-phase coil groups 17u to the starting wire Ws of the other of the two W-phase coil groups 17w.

[0072] Each of the three busbars 50 may have a base portion 51 that extends circumferentially and is covered (embedded) in the holder 40, as shown in Figure 9. The base portion 51 may be, for example, a long plate extending circumferentially. The three base portions 51 may be located in the same axial position and not overlap each other when viewed from the axial direction, that is, they may be located on the same plane.

[0073] The initial wire Ws of each coil group 17 is joined to a part 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 will be referred to as the joining portion 52. As shown in Figure 3, the U-line busbar 50u, V-line busbar 50v, and W-line busbar 50w are each initial wires Ws of different phase coil groups 17, and may be connected to each other by drawing out the initial wires Ws from a common slot 15. Correspondingly, each busbar 50 is provided with one joining portion 52, and the joining portion 52 of each busbar 50 may be provided so as to overlap axially with the slot 15 from which the initial wire Ws connected by that busbar 50 are drawn.

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

[0075] Each busbar 50 may also be provided as a terminal electrically connected to an external power supply device (not shown). In this case, each busbar 50 may further have a terminal portion 53 that is erected from the end of the substrate portion 51 in the extending direction toward the second axial direction Da2 and connected to the external power supply device.

[0076] As described above, the holder 40 is a resin component that covers the base portion 51 of the bus bar 50 and is mounted on the stator 3. The holder 40 may be provided with a main body portion 41 for covering the base portion 51 of each bus bar 50. If each bus bar 50 is provided as a terminal, the holder 40 may be provided with a protrusion 42 for covering the portion of the terminal portion 53 of each bus bar 50 on the first axial direction Da1 side.

[0077] The main body portion 41, for example, has an annular (donut shape) when viewed from the axial direction and a flat plate shape when viewed from the radial direction. The main body portion 41 may have through holes 43 and notches 44 around the joint portion 52 as part of a configuration to reduce the man-hours required for assembling the second busbar unit 5 to the stator 3 and for connecting the initial wire Ws. There may be three through holes 43 and three notches 44, corresponding to the three joint portions 52.

[0078] The through-hole 43 is a hole that penetrates axially through which the initial wire Ws is inserted. The notch 44 is a portion of the main body 41 that is cut out from the second axial direction Da2 side, either radially inside or radially outside the through-hole 43, so as to expose the joint portion 52 of the substrate portion 51 in the second axial direction Da2. The notch 44 may be provided adjacent to the radially inside of the through-hole 43, corresponding to the arrangement where the joint portion 52 is located radially inside the initial wire Ws.

[0079] The initial wires Ws of the different phase coil groups 17 connected by each busbar 50 are drawn out, for example, from a common slot 15 and inserted through a common through hole 43, as shown in Figure 9. The portion of the winding W forming each coil group 17 that is drawn out towards the second axial direction Da2 is the initial wire Ws, which is a fixed end. As described above, the initial wires Ws have the characteristic that the position of the initial wires Ws does not vary much for each coil group 17, so it is possible to insert the initial wires Ws through the through hole 43 simply by placing the second busbar unit 5 on the stator 3. Therefore, the process of adjusting the position of the initial wires Ws or locking the initial wires Ws somewhere is unnecessary, thus reducing the man-hours required for assembling the second busbar unit 5 to the stator 3. In addition, it is possible to draw out the initial wires Ws with high reproducibility to a position suitable for joining to the joint 52, that is, a position that passes through the through hole 43.

[0080] The initial wire Ws, inserted through the through hole 43, is folded radially inward and contacts the joint 52, which is exposed in the second axial direction Da2 by the notch 44, from the second axial direction Da2 side. The initial wire Ws that contacts the joint 52 is joined to the joint 52 not by manual soldering, but by spot welding, which involves applying pressure from the second axial direction Da2 side to melt and bond the joint 52 and the initial wire Ws together. This reduces the man-hours required for the connection process of the initial wire Ws.

[0081] The joint 52, which is pressed in the first axial direction Da1 during spot welding, is supported by a base plate portion 51 covering the main body portion 41 of the holder 40 mounted on the stator 3. Therefore, movement of the joint 52 toward the first axial direction Da1 and the busbar 50 falling out are suppressed during spot welding. In other words, in this embodiment, the base plate portion 51 is covered on the holder 40 mounted on the stator 3, and a notch 44 is provided in the base plate portion 51 that exposes the joint 52 toward the second axial direction Da2, making it possible to join the joint 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 52 is the starting wire Ws, which is less prone to variations in its drawing position. Moreover, since these starting wires Ws are always drawn out from the through hole 43, the reproducibility of the position of the starting wire Ws that will be spot-welded is improved. Therefore, when automating the joining process of the starting wires Ws and incorporating it into the manufacturing process of the motor 1, it is possible to suppress the complexity of handling the starting wires Ws.

[0083] [2. Operation and Effects] (1) In the first busbar unit 4 described above, the holder 20 has an annular region R with 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. Furthermore, the centers of the arcs of each busbar 30 are offset from each other, and at least a part of each busbar 30 overlaps with other busbars 30 within a predetermined angular range of the annular region R. As a result, the axial thickness of the part of the holder 20 that covers the multiple busbars 30 (the main body portion 21 in this embodiment) can be reduced. Therefore, space can be saved inside the motor 1 in the axial direction, and thus the increase in motor size can be suppressed.

[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 to the same phase are covered by the holder 20 at the same axial position relative to the holder 20. As a result, the axial thickness of the part of the holder 20 that is covered by these busbars 30 (the main body portion 21 in this embodiment) can be reduced. Therefore, space can be saved inside the motor 1 in the axial direction, and thus the increase in motor size can be suppressed.

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

[0086] (3) In the first busbar unit 4 described above, the first joint portion 33 of the busbar 30 covered by the holder 20 mounted 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 mounted on the stator 3 is exposed in the first axial direction Da1 by the second notch 25. As a result, before the first busbar unit 4 is mounted on the stator 3, the end wires Wf hooked on the radially inward and radially outward sides can be joined to the first joint portion 33 and the second joint portion 34, respectively, by spot welding from the first axial direction Da1 side. Therefore, the assembly man-hours can be reduced compared to manual soldering.

[0087] (4) Furthermore, in the first busbar unit 4 described above, of the first part 31, only the first joint 33 is exposed in the first axial direction Da1 by the first notch 24, and the portions adjacent to both sides of the first joint 33 are covered by the holder 20 without being exposed. Also, of the second part 32, only the second joint 34 is exposed in the first axial direction Da1 by the second notch 25, and the portions adjacent to both sides of the second joint 34 are covered by the holder 20 without being exposed. As a result, each joint 33, 34 is supported at both ends, so that the end wire Wf can be joined to each joint 33, 34 more appropriately.

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

[0089] (6) If the ends of the windings W that form each coil group 17 are all free ends that are drawn out toward the first axial direction Da1, then hooking the ends of

[0090] (7) If the overlapping length L between the first portion 31 of each busbar 30 and the second portion 32 of another busbar 30 in the circumferential direction is approximately equal to the length of the arc of a sector having a central angle of 360° divided by the number of slots 15 of the stator 3, then compared to the case where the overlapping length L between the first portion 31 and the second portion 32 is longer than the length of this arc, it becomes easier to insulate the busbars 30 from each other and the complexity of the wiring of the end wire Wf can be suppressed.

[0091] (8) If the three busbars 30 provided in the first busbar unit 4 are all the same shape, then the parts (busbars 30) can be standardized. Therefore, this can contribute to reducing the manufacturing cost of the motor 1.

[0092] [3. Others] The configuration of the first busbar unit 4 and motor 1 described above is merely an example and is not limited to the above configuration. For example, the motor 1 may be configured such that the second busbar unit 5, stator 3, and 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 claim is the second axial direction Da2. The first circumferential direction Dc1 and the second circumferential direction Dc2 in the first busbar unit 4 described above are merely examples and these directions may be defined in reverse.

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

[0094] The busbar unit provided on the second axial direction Da2 side of the stator 3 does not have to be a second busbar unit 5 that connects the three-phase coils 16 in a delta connection (triangular connection) configuration; it may also be a busbar unit that connects the three-phase coils 16 in a star connection configuration. Furthermore, the motor 1 does not necessarily have to be equipped with a second busbar unit 5.

[0095] The winding W does not necessarily have to form two adjacent, in-phase coils 16; for example, it may form a single coil 16. That is, the number of windings W provided on the stator 3 is not limited to the six described above. The number of coils 16 provided on the stator 3 does not necessarily have to be twelve; it should be at least a multiple of six.

[0096] Of the windings W that form each coil 16 (coil group 17), the portion drawn out toward the first axial direction Da1 does not have to be the terminal wire Wf. In other words, the busbar 30 of the first busbar unit 4 does not have to connect the terminal wires Wf of each coil 16 (coil group 17). Furthermore, the terminal wires Wf of windings W that form coils 16 of different phases adjacent in the circumferential direction 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 radially inward (protruding) from the holder 20 and functions as a first joint 33, the first notch 24 can be omitted. Similarly, if the second end 36 of each busbar 30 is positioned radially outward (protruding) from the holder 20 and functions as a second joint 34, the second notch 25 can be omitted.

[0098] Furthermore, in the above-described embodiment, the portions adjacent to both sides of the first joint 33 and the second joint 34 were covered by the holder 20 of the first busbar unit 4 without being exposed, but some of these adjacent portions may be exposed from the holder 20. The grooves 37 provided in each joint 33 and 34 may be omitted. The outer wall portion 22 and 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 mounted on the first axial direction Da1 side of the stator 3.

[0099] The holder 20 described in claim 1 of the claims is at least annular in shape surrounding its axis and capable of covering a plurality of busbars 30, and does not have to be annular. The holder 20 may be non-circular, such as polygonal or elliptical, and the main body 21 of the holder 20 does not have to be plate-shaped when viewed radially. The busbars 30 described in claim 1 of the claims are at least arc-shaped with their centers offset from each other, and do not have to be arc-shaped. For example, if the holder 20 is elliptical, the busbars 30 may be elliptical arcs arranged within the annular region of this elliptical shape.

[0100] The holder 20 as described in claim 3 of the claims may be any shape that can cover at least a plurality of busbars 30, and does not have to be annular. The holder 20 may be, for example, disc-shaped, fan-shaped, or rectangular, and the main body 21 of the holder 20 does not have to be plate-shaped when viewed radially. The busbar 30 as described in claim 3 of the claims may be any shape that extends along the circumferential direction, and the first portion 31 of each busbar 30 is located radially inward from the second portion, and does not have to be an eccentric arc shape from the axis C. The busbar 30 may be, for example, spiral-shaped and extend so that it is located radially outward from the first circumferential direction Dc1 to the second circumferential direction Dc2.

[0101] The number of busbars in a busbar unit is not limited to three. Furthermore, the busbars in a busbar unit do not all have to be of the same shape.

[0102] 1 Motor (brushless motor) 1s Shaft 2 Rotor 3 Stator 4 First busbar unit (busbar unit) 15 Slot 16 Coil 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 First notch 25 Second notch 30 Busbar 30u U-phase busbar (busbar) 30v V-phase busbar (busbar) 30w W-phase busbar (busbar) 31 First part 32 Second part 33 First joint 34 Second joint 37 Groove α Determined angle C Axis Cu U-phase busbar center (center of arc) Cv V-phase busbar center (center of the arc) Cw W-phase busbar center (center of the arc) Da1 First axis direction (predetermined axis direction) H Determined radial width L Overlap length (length over which the first part of the busbar and the second part of any other busbar overlap in the circumferential direction) P Plane R Annular region W Winding Wf End line

Claims

1. A busbar unit comprising a plurality of arc-shaped busbars and a holder that covers the plurality of busbars and is annular around an axis, wherein 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 busbars is arranged within the annular region and the centers of the arcs are offset from each other, and at least a portion of each busbar overlaps with the other busbars within a predetermined angular range of the annular region.

2. The busbar unit according to claim 1, characterized in that each of the busbars has the same shape.

3. A busbar unit for an inner rotor type brushless motor comprising an annular stator and a rotor located radially inward of the stator, the busbar unit comprising: a resin holder mounted 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 according to their respective phases, wherein each busbar extends along the circumferential direction of the stator and is covered by the holder at the same axial position relative to the holder, the first portion on one end in the circumferential direction is located inward of the second portion on the other end in the circumferential direction, and the first portion of each busbar and the second portion of any other busbar overlap when viewed from the radial direction.

4. The busbar unit according to claim 3, wherein each of the busbars has a first joint provided in the first part, to which a winding forming one of the two coils connected by the busbar is joined; and a second joint provided in the second part, to which a winding forming the other of the two coils is joined; and the holder has a first notch recessed from the inside to expose the first joint in the predetermined axial direction, and a second notch recessed from the radially outward to expose the second joint in the predetermined axial direction.

5. The busbar unit according to claim 4, characterized in that the end wires of the windings of the two coils are joined to the first joint and the second joint, respectively.

6. The busbar unit according to claim 4, characterized in that the portions adjacent to both sides in the circumferential direction of the first joint in the first portion, and the portions adjacent to both sides in the circumferential direction of the second joint in the second portion, are all covered by the holder.

7. The busbar unit according to claim 4, characterized in that grooves for hooking the windings are provided on the inner side of the first joint and the outer side of the second joint.

8. The busbar unit according to claim 3, characterized in that the length over which the first portion of each of the busbars and the second portion of any other busbar overlap in the circumferential direction is approximately equal to the length of the arc of a sector having a central angle of 360° divided by the number of slots of the stator.

9. The busbar unit according to claim 3, characterized in that each of the busbars has the same shape.

10. A brushless motor comprising: a busbar unit according to any one of claims 3 to 9; a stator on which the busbar unit is mounted; and a rotor that rotates integrally with a shaft on the inner side of the stator.

Images