Motor

Abstract

A motor comprises: a stator (33) having a plurality of coils (28) wound in the same direction; a plurality of first bus bars (50); and a plurality of second bus bars (51). The plurality of coils (28) include a first coil (28) and a second coil (28) adjacent to each other in the circumferential direction. One first bus bar (50) of the plurality of first bus bars (50) is electrically connected to one end (28b) of the first coil (28) and one end (28b) of the second coil (28), and one second bus bar (51) of the plurality of second bus bars (51) is electrically connected to the other end (28a) of the first coil (28). The other second bus bar (51) of the second bus bars (51) is electrically connected to the other end (28a) of the second coil (28).

Description

Motor

[0001] The present invention relates to a motor.

[0002] Patent Document 1 discloses a motor having a bus bar for supplying current to a plurality of coils of a stator, each of which is wound around an insulator around an axis defined in the radial direction, for example.

[0003] JP 2014-11954 A

[0004] In such motors, the coils are wound in different directions depending on the direction of the current flowing through them. Specifically, some coils are wound clockwise and some are wound counterclockwise. This makes the process of connecting the busbars to the coils complicated.

[0005] Therefore, one object of the present invention is to provide a motor that can improve the workability of connecting the bus bars and the coils.

[0006] A motor according to one aspect of the present invention comprises a stator having a plurality of coils wound in the same direction, a plurality of first bus bars, and a plurality of second bus bars, wherein the plurality of coils include a first coil and a second coil adjacent to each other in the circumferential direction, one first bus bar of the plurality of first bus bars is electrically connected to one end of the first coil and one end of the second coil, one second bus bar of the plurality of second bus bars is electrically connected to the other end of the first coil, and another second bus bar of the plurality of second bus bars is electrically connected to the other end of the second coil.

[0007] A motor according to another aspect of the present invention comprises a plurality of coils wound in the same direction, a first bus bar electrically connected to one end of adjacent first and second coils among the plurality of coils, a second bus bar electrically connected to the other end of the first coil, and a third bus bar electrically connected to the other end of the second coil, wherein the direction of the current flowing through the first coil and the direction of the current flowing through the second coil are opposite to each other.

[0008] 1 is a perspective view schematically illustrating the structure of a motor 1 according to an embodiment of the present invention; FIG. 2 is a vertical cross-sectional view schematically illustrating the structure of a motor 1 according to an embodiment of the present invention; FIG. 3 is a horizontal cross-sectional view schematically illustrating the structure of a motor 1 according to an embodiment of the present invention; FIG. 4 is a perspective view schematically illustrating the structure of a stator assembly 25 according to a specific example; FIG. 5 is an exploded perspective view of the stator assembly 25 with the bus bar unit 40 removed; FIG. 6 is an exploded perspective view schematically illustrating the structure of a bus bar unit 40 according to a specific example; FIG. 7 is a perspective view showing only six first bus bars 50 arranged above a coil 28; FIG. 8 is a perspective view showing a state in which a lower second bus bar 51 of the three is stacked on the six first bus bars 50; FIG. 9 is a perspective view showing a state in which a middle second bus bar 51 of the three is further stacked on the lower second bus bar 51; FIG. 10 is a perspective view showing a state in which an upper second bus bar 51 of the three is further stacked on the middle second bus bar 51.

[0009] An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a perspective view that schematically shows the structure of a motor 1 according to an embodiment of the present invention. Fig. 2 is a vertical sectional view that schematically shows the structure of a motor 1 according to an embodiment of the present invention. Fig. 3 is a horizontal sectional view that schematically shows the structure of a motor 1 according to an embodiment of the present invention. Note that Fig. 2 corresponds to the 2-2 sectional view of Fig. 1 taken along an imaginary plane including an axis x that constitutes the rotational axis of the motor 1. Furthermore, Fig. 3 corresponds to the 3-3 sectional view of Fig. 2 taken along an imaginary plane perpendicular to the axis x.

[0010] In the following description of the embodiment of the motor 1, one side in the direction along the axis x (hereinafter referred to as the "axial direction") is defined as the upper side, and the other side as the lower side. The upper and lower sides defined in the axial direction do not necessarily correspond to the up-and-down relationship in the direction of gravity. Furthermore, the radial direction of the motor 1 is defined as a direction perpendicular to the axis x. In this radial direction, the side away from the axis x is defined as the outer side (outer circumferential side) in the radial direction, while the side approaching the axis x is defined as the inner side (inner circumferential side) in the radial direction. Furthermore, the circumferential direction of the motor 1 is defined around the axis x.

[0011] 1 to 3, the motor 1 includes, for example, a cylindrical shaft 10 whose central axis is axis x. The shaft 10 is rotatably supported by two bearings 12 and 13 fixed to a housing 11. The bearings 12 and 13 are attached between the shaft 10 and the housing 11 by, for example, press fitting. The bearings 12 and 13 are, for example, ball bearings. In this example, the shaft 10 protrudes further below the bottom end of the housing 11 than above the top end of the housing 11.

[0012] The housing 11 has, for example, a cylindrical main body (hereinafter referred to as the "housing main body") 14 and, for example, a disk-shaped cover 15. The lower end of the housing main body 14 is open, while the upper end of the housing main body 14 is closed by the housing main body 14 having an upper portion. The lower end of the housing main body 14 is covered and closed by the cover 15. The shaft 10 protrudes outside the housing 11 from an opening 16 formed at the upper end of the housing main body 14 and an opening 17 formed in the cover 15. A flange 14a protruding in a predetermined shape in the radial direction is formed at the lower end of the housing main body 14. This flange 14a is used, for example, to attach the motor 1 to a predetermined application.

[0013] A cylindrical rotor core 18, for example, is fixed to the shaft 10 between the bearings 12, 13 in the axial direction. The rotor core 18 is formed from a laminate of multiple magnetic materials stacked in the axial direction. As is clear from FIG. 3 , the rotor core 18 has, for example, a cylindrical inner peripheral portion 19, a cylindrical outer peripheral portion 20, and multiple connection portions 21 that connect the inner peripheral portion 19 and the outer peripheral portion 20 to each other. The rotor core 18 is fixed by inserting the shaft 10 into a hole formed in the inner peripheral portion 19 along the axis x. Each connection portion 21 is formed, for example, in the shape of a vertically elongated flat plate extending in the radial direction.

[0014] A plurality of magnets 22 are embedded in the outer peripheral portion 20 of the rotor core 18 in close proximity to its outer peripheral surface. The magnets 22 are, for example, permanent magnets. Each magnet 22 is fixed, for example, in a through-hole 23 in the outer peripheral portion 20 that extends axially in close proximity to the outer peripheral surface of the rotor core 18. The magnets 22 are arranged in the circumferential direction, with their magnetic poles oriented alternately as north and south poles in the circumferential direction. This motor 1 is a so-called interior permanent magnet (IPM) motor. The rotor core 18 and the magnets 22 form a rotor 24 of the motor 1. In other words, the motor 1 is an inner rotor type motor.

[0015] A stator assembly 25 is housed within the housing 11. The stator assembly 25 has a stator core 26, multiple insulators 27, and multiple coils 28. The stator core 26 is fixed to the inner circumferential surface of the housing main body 14. Multiple coils 28 are wound around the stator core 26, arranged in the circumferential direction. The stator core 26 is formed from a laminate of a magnetic material such as silicon steel plate. The coils 28 are made of copper wire, for example. The insulators 27 are formed from an insulating material such as a resin material. The insulators 27, which are arranged between the stator core 26 and the coils 28, insulate the stator core 26 from the coils 28.

[0016] As shown in FIG. 3 , the stator core 26 has a cylindrical tubular portion 29 and a plurality of teeth 30. The outer peripheral surface of the tubular portion 29 is fixed to the inner peripheral surface of the housing main body 14. Each tooth 30 has a spoke 31 and a magnetic pole portion 32. The spoke 31 extends radially from its outer peripheral end to its inner peripheral end. The magnetic pole portions 32 are continuous with the inner peripheral ends of the spokes 31. The magnetic pole portions 32 protrude circumferentially in opposite directions from each other from the spoke 31. The inner peripheral surfaces of the magnetic pole portions 32 of the teeth 30 face the outer peripheral surface of the outer peripheral portion 20 of the rotor core 18 with a predetermined magnetic gap between them. A coil 28 is wound around each spoke 31 via an insulator 27. The stator core 26, the insulator 27, and the coil 28 constitute a stator 33 of the motor 1.

[0017] FIG. 4 is a perspective view schematically illustrating the structure of a stator assembly 25 according to one specific example. FIG. 5 is an exploded perspective view of the stator assembly 25 with the busbar unit 40 removed. Referring to FIGS. 2, 4, and 5 together, the stator assembly 25 has a busbar unit 40. The busbar unit 40 is disposed between the coil 28 and the upper end of the housing main body 14. The busbar unit 40 has an annular housing 41 and a busbar group 42 as a conductive member housed in the housing 41. The busbar unit 40 is configured to supply current to the coil 28 from an external power source (not shown) via the busbar group 42.

[0018] The bus bar group 42 includes a plurality of terminals (second terminals, hereinafter referred to as "outer terminals") 43 extending from the housing 41 toward the outer periphery, in this example, twelve terminals, a plurality of terminals (first terminals, hereinafter referred to as "inner terminals") 44 extending from the housing 41 toward the inner periphery, in this example, twelve terminals, and a plurality of terminals (hereinafter referred to as "external terminals") 45 extending upward from the housing 41, in this example, three terminals (hereinafter referred to as "external terminals"). The outer terminals 43 and the inner terminals 44 are fork-shaped terminals. The outer terminals 43 are disposed on the outer periphery side of the housing 41, while the inner terminals 44 are disposed on the inner periphery side of the housing 41. That is, the outer terminals 43 and the inner terminals 44 are disposed at different positions in the radial direction. In this example, the external terminal 45 extends upward on the outer periphery side of the housing 41.

[0019] The plurality of outer terminals 43 and the plurality of inner terminals 44 are electrically connected to the coils 28 based on a predetermined wiring circuit, while the external terminal 45 is electrically connected to an external device (not shown). The external device includes a power source that supplies current to the motor 1. Details of the wiring circuit will be described later. As shown in FIGS. 1 and 2 , the external terminal 45 protrudes upward to the outside of the housing 11 through an opening 14b formed at the upper end of the housing main body 14. In this example, three external terminals 45 are arranged at equal intervals in the circumferential direction. Each external terminal 45 is electrically connected to an external device by wiring (not shown) or the like.

[0020] Each coil 28 has the other end (hereinafter referred to as the "outer end") 28a drawn upward from the outer periphery, and one end (hereinafter referred to as the "inner end") 28b drawn upward from the inner periphery. In this example, all of the coils 28 are wound in the same direction around the spokes 31 around an axis defined in the radial direction. All of the coils 28 are also wound in the same manner around their respective spokes 31. The multiple outer ends 28a and the multiple inner ends 28b are each arranged at equal intervals in the circumferential direction. In this example, 12 coils 28 are arranged in the circumferential direction, so that the 12 outer ends 28a are arranged at predetermined intervals (e.g., equal intervals), and the 12 inner ends 28b are arranged at predetermined intervals (e.g., equal intervals).

[0021] Each outer terminal 43 has a recessed groove (recessed groove) 43a extending from the outer peripheral end of the outer terminal 43 toward the inner peripheral side. The outer end 28a is received in this recessed groove 43a, and each coil 28 is electrically connected to the outer terminal 43. Similarly, each inner terminal 44 has a recessed groove (recessed groove) 44a extending from the inner peripheral end of the inner terminal 44 toward the outer peripheral side. The inner end 28b is received in this recessed groove 44a, and each coil 28 is electrically connected to the inner terminal 44. Note that each outer terminal 43 and each inner terminal 44 may be crimped to the outer terminal 43 and each inner terminal 44, respectively. Alternatively, the outer end 28a and the inner end 28b may be joined to the outer terminal 43 and each inner terminal 44 using a joining material (solder).

[0022] FIG. 6 is an exploded perspective view schematically illustrating the structure of a busbar unit 40 according to one specific example. As shown in FIG. 6 , the housing 41 of the busbar unit 40 includes a base 46 that houses a busbar group 42 and a cover 47 that covers the upper end of the base 46. Both the base 46 and the cover 47 are formed from an insulating material that includes a resin material. The busbar group 42 includes a plurality of first busbars 50 and a plurality of second busbars 51. In this example, the first busbars 50 are arranged in the circumferential direction. Meanwhile, three second busbars 51 are arranged axially above the first busbar 50. The first busbars 50 and the second busbars 51 are formed from a conductive material that includes a metal material such as copper or aluminum.

[0023] Each first bus bar 50 has a portion 52 extending in an arc shape in the circumferential direction and a plurality of inner terminals 44, 44 extending inward from the portion 52, in this example, a pair of inner terminals. The pair of inner terminals 44, 44 are arranged at a predetermined interval in the circumferential direction. Two adjacent first bus bars 50, 50 in the circumferential direction are arranged spaced apart in the circumferential direction. In this example, all of the first bus bars 50 have the same shape. On the other hand, each second bus bar 51 has a portion 53 extending in an annular shape in the circumferential direction, a plurality of outer terminals 43, in this example, four, extending outward from the portion 53, and one external terminal 45 extending upward. In this example, the portion 53 is formed in a continuous annular shape. The outer terminals 43 and the external terminals 45 are arranged at predetermined intervals (e.g., equal intervals) in the circumferential direction. All of the second bus bars 51 have the same shape.

[0024] Insulating members 54 are disposed between axially adjacent first bus bars 50 and second bus bars 51 and between axially adjacent second bus bars 51. In this example, the insulating members 54 are formed, for example, from an annular member formed into a flat sheet. The insulating members 54 are formed, for example, from an insulating material containing a resin material. In this example, in a plan view from above, the contour of the insulating members 54 substantially matches the contour of the second bus bars 51 in a plan view from above. The insulating members 54 function to establish insulation between axially adjacent first bus bars 50 and second bus bars 51, and between axially adjacent second bus bars 51, 51. In the bus bar unit 40, the first bus bars 50, second bus bars 51, and insulating members 54 are stacked in the axial direction.

[0025] The base 46 of the housing 41 defines an annular space that accommodates the bus bar group 42. This annular space is closed by a cover 47. A plurality of recesses 46a are formed in the outer peripheral sidewall of the base 46. The recesses 46a are recessed downward from the upper end of the outer peripheral sidewall. Each recess 46a can accommodate an outer terminal 43. Meanwhile, a plurality of recesses 46b are formed in the inner peripheral sidewall of the base 46. The recesses 46b are recessed downward from the upper end of the inner peripheral sidewall. Each recess 46b can accommodate an inner terminal 44. When the bus bar group 42 is accommodated in the annular space of the base 46, the inner terminal 44 of the first bus bar 50 protrudes inner from the recesses 46b, and the outer terminal 43 of the second bus bar 51 protrudes outer from the recesses 46a.

[0026] The cover 47 of the housing 41 has an annular portion 47a that closes the annular space of the base 46, multiple holding portions 47b arranged on the outer periphery of the portion 47a, and multiple protrusions 47c that protrude downward from the outer and inner periphery edges of the portion 47a. The portion 47a extends, for example, along a plane perpendicular to the axis x. The holding portions 47b are formed in a cylindrical shape that can hold the external terminals 45 of the second bus bar 51. As shown in FIG. 1 , the holding portions 47b partially protrude outside the housing 11 through the opening 14b of the housing main body 14 of the motor 1. When the cover 47 is attached to the base 46, the protrusions 47c are received in the recesses 46a, 46b of the base 46.

[0027] Next, the electrical connection between the busbar group 42 of the busbar unit 40 and the plurality of coils 28 will be described. Fig. 7 is a perspective view showing a state in which only the first busbar 50 is arranged above the coils 28. In this example, the plurality of coils 28 are respectively assigned reference numerals 28A to 28L in circumferential order. Similarly, the first busbars 50 are respectively assigned reference numerals 50A to 50F in circumferential order. The inner terminals 44, 44 of the first busbar 50A are electrically connected to the inner end 28b of the coil 28A and the inner end 28b of the coil 28B, respectively.

[0028] The inner terminals 44 of the second bus bar 50B are electrically connected to the inner ends 28b of the coils 28C and 28D, respectively. Similarly, the inner terminal 44 of the second bus bar 50C is electrically connected to the inner ends 28b of the coils 28E and 28F, the inner terminal 44 of the second bus bar 50D is electrically connected to the inner ends 28b of the coils 28G and 28H, the inner terminal 44 of the second bus bar 50E is electrically connected to the inner ends 28b of the coils 28I and 28J, and the inner terminal 44 of the second bus bar 50F is electrically connected to the inner ends 28b of the coils 28K and 28L. In this manner, the first bus bars 50A to 50F electrically connect pairs of circumferentially adjacent coils 28, 28, respectively.

[0029] FIG. 8 is a perspective view showing a state in which the lower second bus bar 51 of the three first bus bars 50A-50F is stacked on top of the first bus bars 50A-50F arranged in the circumferential direction. In this example, the lower second bus bar 51 is designated by the reference numeral 51A. As shown in FIG. 8, the four outer terminals 43 of this second bus bar 51A are electrically connected to the outer ends 28a of the coils 28A, 28F, 28H, and 28K, respectively. The external terminal 45 of the second bus bar 51A is disposed above the coil 28C in the axial direction. In this manner, one second bus bar 51A is electrically connected to four coils 28.

[0030] 9 is a perspective view showing a state in which the middle second bus bar 51 of the three is further stacked on top of the lower second bus bar 51A. In this example, the middle second bus bar 51 is designated by the reference numeral 51B. As shown in FIG. 9, the four outer terminals 43 of this second bus bar 51B are electrically connected to the outer ends 28a of coils 28B, 28D, 28G, and 28I, respectively. The external terminal 45 of the second bus bar 51B is disposed above coil 28K in the axial direction. In this manner, one second bus bar 51B is electrically connected to four coils 28.

[0031] FIG. 10 is a perspective view showing a state in which the upper second bus bar 51 of the three bus bars is further stacked on top of the middle second bus bar 51B. In this example, the upper second bus bar 51 is designated by the reference numeral 51C. As shown in FIG. 10 , the four outer terminals 43 of this second bus bar 51C are electrically connected to the outer ends 28a of the coils 28C, 28E, 28J, and 28L, respectively. The external terminal 45 of the second bus bar 51C is disposed above the coil 28G in the axial direction. In this manner, one second bus bar 51C is electrically connected to four coils 28.

[0032] The bus bar unit 40 described above establishes a delta-connected, two-series, two-parallel wiring circuit. In this wiring circuit, the second bus bar 51A on the lower side in the axial direction forms the U-phase, the middle second bus bar 51B forms the V-phase, and the third bus bar 51C on the upper side in the axial direction forms the W-phase. FIG. 11 is a diagram showing the configuration of the wiring circuit of the motor 1. This wiring circuit is composed of three second bus bars 51A, 51B, and 51C that respectively form the U-phase, V-phase, and W-phase, six first bus bars 50A-50F, and 12 coils 28A-28L. As shown in FIG. 11, a pair of circumferentially adjacent coils 28, 28 are electrically connected in series by the second bus bar 51.

[0033] In this stator assembly 25, for example, current flows from an external device into the second bus bar 51A through the external terminal 45 of the second bus bar 51A constituting the U-phase. As shown in FIG. 8 , the current flows from the external terminal 45 of the second bus bar 51A (second bus bar) to the coil 28K (first coil). Then, as shown in FIG. 7 , the current flows from the coil 28K to the first bus bar 50F (first bus bar) and into the coil 28L (second coil) circumferentially adjacent to the coil 28K. As shown in FIG. 10 , the current flows from the coil 28L to the second bus bar 51C (third bus bar) constituting the W-phase and then flows out to the external device through the external terminal 45 of the second bus bar 51C. That is, the current flows in opposite directions in the adjacent coils 28K and 28L.

[0034] In the motor 1 described above, for example, the inner ends 28b of the coils 28K and 28L are electrically connected by the first bus bar 50F. As a result, current flowing from the second bus bar 51A into the coil 28K via the outer end 28a of the coil 28K flows from the inner end 28b to the coil 28L via the first bus bar 50F. The current flows out from the outer end 28a of the coil 28L to the second bus bar 51C. Because adjacent coils 28, 28 wound in the same direction are electrically connected by the second bus bar 51C, a configuration can be established in which current flows in opposite directions between adjacent coils 28, 28. This configuration eliminates the need to change the winding direction for each coil 28, significantly improving the ease of connecting the bus bar unit 40 and the coils 28.

[0035] In the motor 1, the first bus bar 50 has the inner terminal 44 and the second bus bar 51 has the outer terminal 43. However, the opposite configuration may alternatively be established. That is, the first bus bar 50 may have the outer terminal 43, while the second bus bar 51 may have the inner terminal 44. As an alternative example, both the first bus bar 50 and the second bus bar 51 may have the inner terminal 44, or conversely, both the first bus bar 50 and the second bus bar 51 may have the outer terminal 43. In this case, both the other end 28a and one end 28b of the coil 28 may be disposed on the inner circumferential side from the first bus bar 50 and the second bus bar 51, or may be disposed on the outer circumferential side from the first bus bar 50 and the second bus bar 51.

[0036] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects.

[0037] 1 Motor, 10 Shaft, 11 Housing, 12, 13 Bearing, 14 Main body (housing main body), 14a Flange, 14b Opening, 15 Cover, 16 Opening, 17 Opening, 18 Rotor core, 19 Inner peripheral portion, 20 Outer peripheral portion, 21 Connection portion, 22 Magnet, 23 Through hole, 24 Rotor, 25 Stator assembly, 26 Stator core, 27 Insulator, 28, 28A to 28L Coil, 28a Other end (outer end), 28b One end (inner end), 29 Cylindrical portion, 30 Teeth, 31 Spoke, 32 Magnetic pole portion, 33 Stator, 40 Busbar unit, 41 Housing, 42 Busbar group, 43 Terminal (second terminal), 43a Groove (recessed groove), 44 Terminal (first terminal), 44a Groove (recessed groove), 45 Terminal, 46 Base, 46a recess, 46b recess, 47 cover, 47a portion, 47b holding portion, 47c protrusion, 50, 50A to 50F first bus bars, 51, 51A to 51C second bus bars, 52 portion, 53 portion, 54 insulating member, x axis

Claims

1. A motor comprising: a stator having a plurality of coils wound in the same direction; a plurality of first bus bars; and a plurality of second bus bars, wherein the plurality of coils includes a first coil and a second coil adjacent in the circumferential direction; one first bus bar of the plurality of first bus bars is electrically connected to one end of the first coil and one end of the second coil; one second bus bar of the plurality of second bus bars is electrically connected to the other end of the first coil; and another second bus bar of the plurality of second bus bars is electrically connected to the other end of the second coil.

2. The motor according to claim 1, wherein the plurality of first bus bars are arranged in a circumferential direction.

3. The motor according to claim 1 or 2, wherein the plurality of second bus bars are stacked in the axial direction.

4. The motor according to any one of claims 1 to 3, wherein each of the plurality of second bus bars has a terminal for electrical connection to an external device.

5. A motor according to any one of claims 1 to 4, wherein a plurality of terminals of the first bus bar are electrically connected to one end of the first coil and one end of the second coil.

6. The motor according to claim 5, wherein a terminal of one of the second bus bars is electrically connected to the other end of the first coil, and a terminal of the other of the second bus bars is electrically connected to the other end of the second coil.

7. The motor according to any one of claims 1 to 6, wherein the first bus bar comprises a portion extending in a circumferential direction and the plurality of terminals extending radially inward.

8. A motor according to any one of claims 1 to 7, wherein the second bus bar comprises a portion extending in a circumferential direction and the plurality of terminals extending radially outward.

9. A motor comprising: a plurality of coils wound in the same direction; a first bus bar electrically connected to one end of adjacent first and second coils among the plurality of coils; a second bus bar electrically connected to the other end of the first coil; and a third bus bar electrically connected to the other end of the second coil, wherein the direction of the current flowing through the first coil and the direction of the current flowing through the second coil are opposite to each other.

10. The motor according to claim 9, wherein the first bus bar, the second bus bar, and the third bus bar are formed from different materials.

11. The motor according to claim 9 or 10, wherein the first bus bar has two first terminals electrically connected to the first coil and the second coil, and the second bus bar has a second terminal electrically connected to the first coil, and the two first terminals and the second terminal are located at different positions in the radial direction.

12. The motor of claim 11, wherein said two first terminals extend radially inward and said second terminals extend radially outward.

13. A motor according to any one of claims 9 to 12, wherein the second bus bar and the third bus bar each have a terminal for electrical connection to an external device.

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