Motor

Abstract

To provide a motor which can be miniaturized.SOLUTION: A motor 1 includes a conductive wire 28a forming a coil 28, and a plurality of bus bars 50A to 50C. The conductive wire 28a is electrically connected to the plurality of bus bars 50A to 50C, and a portion of a second bus bar 50B overlaps a step part of a first bus bar 50C among the plurality of bus bars 50A to 50C in an axial direction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a motor. [Background technology]

[0002] For example, in Patent Document 1, a plurality of busbar units stacked in the axial direction are used to supply current to a motor. Each busbar unit has a busbar and a resin holder that holds the busbar. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-085456 Summary of the Invention [Problem to be solved by the invention]

[0004] In these motors, the thickness of the busbars needs to be increased to handle high currents. In that case, the busbar unit must be made larger in the axial direction by the number of busbars stacked in the axial direction, which results in an increased motor size.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor that can be made smaller. [Means for solving the problem]

[0006] A motor according to one aspect of the present invention includes a conductor forming a coil and a plurality of bus bars, the conductor being electrically connected to the plurality of bus bars, and a portion of the second bus bar overlapping a step portion of a first bus bar among the plurality of bus bars in the direction of the rotation axis. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a perspective view showing a schematic structure of a motor 1 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. [Figure 4] FIG. 2 is a perspective view schematically illustrating the structure of a stator assembly 25 according to one specific example. [Figure 5] FIG. 2 is an exploded perspective view schematically illustrating the structure of a stator assembly 25 according to one specific example. [Figure 6] FIG. 2 is an exploded perspective view schematically illustrating the structure of a busbar unit 40 according to a specific example. [Figure 7] FIG. 2 is a perspective view schematically illustrating the structure of a busbar group 42 according to a specific example. [Figure 8] FIG. 10 is a perspective view schematically illustrating the structure of a busbar unit 40A according to another specific example. [Figure 9] FIG. 10 is an exploded perspective view schematically illustrating the structure of a busbar unit 40A according to another specific example. [Figure 10] FIG. 10 is a perspective view schematically illustrating the structure of a busbar group 42A according to another specific example. [Figure 11] FIG. 11 is a partially enlarged cross-sectional view taken along line 11-11 in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0008] 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 a sectional view taken along line 2-2 in FIG. 1, along an imaginary plane that includes an axis x that constitutes the rotational axis of the motor 1. Also, FIG. 3 corresponds to a sectional view taken along line 3-3 in FIG. 2, along an imaginary plane that is perpendicular to the axis x.

[0009] 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 opposite the one side as the lower side. These upper and lower sides defined in the axial direction do not necessarily coincide with 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.

[0010] 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.

[0011] 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 part. 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.

[0012] A cylindrical rotor core 18, for example, is fixed to the shaft 10 between the bearings 12 and 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 with its central axis coincident with the axis x, a cylindrical outer peripheral portion 20 with its central axis also coincident with the axis x, and multiple connecting portions 21 connecting 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 connecting portion 21 is formed, for example, in the shape of a long, flat plate extending in the radial direction.

[0013] 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.

[0014] A stator assembly 25 is accommodated within the housing 11. The stator assembly 25 has a stator core 26, a plurality of insulators 27, and a plurality of coils 28. The stator core 26 is fixed to the inner circumferential surface of the housing body 14. A plurality of coils 28 arranged in the circumferential direction are wound around the stator core 26. The stator core 26 is formed from a laminated body of a magnetic material such as silicon steel plate. The coils 28 are formed from, for example, conductive wires 28a. 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.

[0015] As shown in FIG. 3 , the stator core 26 has a cylindrical tubular portion 29 and a plurality of teeth 30. The outer circumferential surface of the tubular portion 29 is fixed to the inner circumferential 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 circumferential end to its inner circumferential end. The magnetic pole portions 32 are continuous with the inner circumferential ends of the spokes 31. The magnetic pole portions 32 protrude circumferentially in opposite directions from the spokes 31. The inner circumferential surfaces of the magnetic pole portions 32 of the teeth 30 face the outer circumferential surface of the outer circumferential portion 20 of the rotor core 18 with a predetermined magnetic gap between them. A conductor 28a of 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.

[0016] 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 schematically illustrating the structure of a stator assembly 25 according to a specific example. Referring to FIGS. 1, 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 casing 41 and a busbar group 42 as a conductive member housed in the casing 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.

[0017] The busbar group 42 includes a plurality of terminals (hereinafter referred to as "outer terminals") 43 extending from the housing 41 toward the outer periphery, in this example, twelve 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. 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 terminals 45 extend upward from the housing 41 on the outer periphery side.

[0018] The plurality of outer terminals 43 and the plurality of inner terminals 44 are electrically connected to the conductors 28a of 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 may include a power source that supplies current to the motor 1. As shown in FIGS. 1 and 2, the external terminals 45 protrude upward to the outside of the housing 11 through openings 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.

[0019] The conductor wire 28a of each coil 28 has one end drawn upward from the outer periphery and the other end 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 and multiple inner ends are each arranged at equal intervals in the circumferential direction. In this example, 12 coils 28 are arranged in the circumferential direction, and therefore the 12 outer ends are arranged at equal intervals and the 12 inner ends are also arranged at equal intervals.

[0020] 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. One end of the conductor 28a is received in this recessed groove 43a, and each conductor 28a 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 other end of the conductor 28a is received in this recessed groove 44a, and each conductor 28a is electrically connected to the inner terminal 44. Note that each outer terminal 43 and each inner terminal 44 may be crimped to each outer terminal 43 and each inner terminal 44. Alternatively, each conductor 28a may be soldered to each outer terminal 43 and each inner terminal 44.

[0021] FIG. 6 is an exploded perspective view schematically illustrating the structure of a busbar unit 40 according to one example. As shown in FIG. 6, a 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 of an insulating material including a resin material. The busbar group 42 includes a plurality of, for example, three first busbars 50A, 50B, and 50C, and a plurality of, for example, six second busbars 60A, 60B, 60C, 60D, 60E, and 60F. The first busbars 50A to 50C are stacked in the axial direction. The second busbars 60A to 60F are arranged in the circumferential direction. The first busbars 50A to 50C and the second busbars 60A to 60F are formed of a conductive material including a metal material such as copper or aluminum.

[0022] The first bus bars 50A to 50C all have the same shape. Each of the first bus bars 50A to 50C has a first portion 51 that extends in an arc shape in the circumferential direction and a second portion 52 that is positioned circumferentially offset from the first portion 51 and also extends in an arc shape in the circumferential direction. In this example, the first portion 51 and the second portion 52 do not overlap in the circumferential direction. The first portion 51 and the second portion 52 are positioned at different heights in the axial direction. Both the first portion 51 and the second portion 52 extend along an imaginary plane perpendicular to the axis x. The first portion 51 and the second portion 52 are connected by a step portion 53. In this example, the first portion 51 is positioned axially lower than the second portion 52. That is, the step portion 53 is formed so as to slope downward from the second portion 52 toward the first portion 51.

[0023] In each of the first bus bars 50A to 50C, the first portion 51 and the second portion 52 each extend over an angle of approximately 120° around the axis x. The first portion 51 and the second portion 52 together extend over an angle of approximately 240°. In other words, the first bus bars 50A to 50C have an end 51a of the first portion 51 and an end 52a of the second portion 52 in the circumferential direction. As will be described later, these first bus bars 50A to 50C are arranged circumferentially offset from each other by an angle of 120°. Two external terminals 43 protrude outward from each of the first portion 51 and the second portion 52. In this example, one external terminal 45 extends upward after protruding outward from the first portion 51.

[0024] FIG. 7 is a perspective view schematically illustrating the structure of a busbar group 42 according to one specific example. Referring to FIGS. 6 and 7 together, the second portion 52 of the first busbar 50C is disposed on the first portion 51 of the first busbar 50A. The second portion 52 of the first busbar 50B is disposed on the first portion 51 of the first busbar 50C. Similarly, the second portion 52 of the first busbar 50A is disposed on the first portion 51 of the first busbar 50B. Thus, for example, a portion of the end portion 52a of the second portion 52 of the first busbar 50B overlaps with the step portion 53 of the first busbar 50C in the axial direction. A portion of the end portion 52a of the second portion 52 of the first busbar 50C overlaps with the step portion 53 of the first busbar 50A in the axial direction. Similarly, a portion of the end portion 52a of the second portion 52 of the first busbar 50A overlaps with the step portion 53 of the first busbar 50B in the axial direction.

[0025] When the first busbars 50A-50C are stacked axially in this manner, twelve external terminals 43 are arranged at predetermined intervals around the axis x. Similarly, three external terminals 45 are arranged at predetermined intervals around the axis x. Furthermore, for example, among the twelve external terminals 43 arranged in the circumferential direction, two circumferentially adjacent external terminals 43 are arranged at different heights in the axial direction. For example, the external terminal 45 of the first busbar 50C is arranged adjacent to the outer circumferential portion 52b of the second portion 52 of the first busbar 50B. The external terminal 45 of the first busbar 50B is arranged adjacent to the outer circumferential portion 52b of the second portion 52 of the first busbar 50A. Similarly, the external terminal 45 of the first busbar 50A is arranged adjacent to the outer circumferential portion 52b of the second portion 52 of the first busbar 50C.

[0026] As shown in FIG. 6 , an insulating member 54 is disposed between the first portion 51 and the second portion 52 that are adjacent in the axial direction. In this example, the insulating member 54 is formed, for example, from a member formed in a flat sheet shape. The insulating member 54 is formed in an arc shape that extends in the circumferential direction over the same angle as the first portion 51 and the second portion 52. Specifically, in a plan view, the contour of the insulating member 54 is defined in substantially the same manner as the contours of the first portion 51 and the second portion 52. The insulating member 54 is formed, for example, from an insulating material containing a resin material. The presence of this insulating member 54 ensures insulation between the first bus bar 50A and the second bus bar 50B that are adjacent in the axial direction, between the first bus bar 50B and the second bus bar 50C that are adjacent in the axial direction, and between the first bus bar 50C and the second bus bar 50A that are adjacent in the axial direction.

[0027] The second bus bars 60A to 60F all have the same shape. As shown in FIG. 7, the second bus bars 60A to 60F are arranged more inwardly than the first bus bars 50A to 50C. The second bus bars 60A to 60F are arranged circumferentially spaced apart and at predetermined intervals in the circumferential direction. Each of the second bus bars 60A to 60F has a wall portion 61 extending in the circumferential direction. The wall portion 61 is formed in an arc shape in a plan view. The wall portion 61 faces the first bus bars 50A to 50C in the radial direction. In this example, the height of the wall portion 61 in the axial direction is set to a size that roughly matches the height of the first bus bars 50A to 50C that are stacked in the axial direction. A plurality of inner terminals 44, two in this example, protrude inward from the lower end of the wall portion 61.

[0028] As shown in FIG. 6 , the base 46 of the housing 41 defines an annular space that houses the bus bar group 42. Specifically, the base 46 has an annular first space 48 that is disposed on the outer periphery and houses the first bus bars 50A-50C, and an annular second space 49 that is disposed on the inner periphery of the first space 48 and houses the second bus bars 60A-60F. The first space 48 and the second space 49 are closed by a cover 47. A plurality of recesses 46a are formed in the outer periphery sidewall of the base 46. Each recess 46a receives an outer terminal 43. Meanwhile, a plurality of recesses 46b are formed in the inner periphery sidewall of the base 46. Each recess 46b receives an inner terminal 44.

[0029] When the first bus bars 50A-50C are accommodated in the annular first space 48 of the base 46, the outer terminals 43 of the first bus bars 50A-50C protrude radially outward from the recesses 46a. Similarly, when the second bus bars 60A-60F are accommodated in the annular second space 49 of the base 46, the inner terminals 44 of the second bus bars 60A-60F protrude radially outward from the recesses 46b. A side wall 46c separating the first space 48 from the second space 49 radially separates the first bus bars 50A-50C from the second bus bars 60A-60F. Because the housing 41 is made of an insulating material containing a resin material, the first bus bars 50A-50C and the second bus bars 60A-60F are insulated from each other.

[0030] In the stator assembly 25 of the motor 1 described above, a portion of the end 52a of the first bus bar 50B (second bus bar) overlaps with the step 53 of the first bus bar 50C (first bus bar) among the first bus bars 50A-50C. The same applies to the first bus bars 50B, 50A and the first bus bars 50A, 50C. In this manner, the three first bus bars 50A-50C can be stacked in two tiers. As a result, the height of the bus bar group 42 in the axial direction can be reduced compared to when, for example, three annular bus bars are stacked in three tiers. Furthermore, the wall portions 61 of the second bus bars 60A-60F (third bus bars) having the inner terminals 44 face the first bus bars 50A-50C in the radial direction. This further reduces the height of the bus bar group 42. This configuration allows the motor 1 to be miniaturized. In other words, the motor length can be reduced, thereby improving the performance of the motor 1.

[0031] FIG. 8 is a perspective view schematically illustrating the structure of a busbar unit 40A according to another specific example. FIG. 9 is an exploded perspective view schematically illustrating the structure of a busbar unit 40A according to another specific example. FIG. 10 is a perspective view schematically illustrating the structure of a busbar group 42A according to another specific example. Referring to FIGS. 8 to 10 together, the busbar unit 40A differs from the busbar unit 40 according to the above-described embodiment in that the busbar unit 40A accommodates a busbar group 42A having a different configuration from the busbar group 42. Specifically, in the busbar group 42A, the outer terminals 43 and the inner terminals 44 are formed with holes 43b and 44b instead of the recessed grooves 43a and 44a. The holes 43b and 44b penetrate the outer terminals 43 and the inner terminals 44 parallel to the axis x. In this example, the inner terminals 44 protrude from the upper end of the wall portion 61 toward the inner periphery. Other components similar to those in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

[0032] FIG. 11 is a partially enlarged cross-sectional view taken along line 11-11 in FIG. 8. FIG. 11 shows a cross-sectional view of an outer terminal 43 as an example. As shown in FIG. 11, the hole 43b of the outer terminal 43 defines a cylindrical space along a central axis parallel to the axis x. A ring-shaped inclined surface (hereinafter referred to as a tapered surface) 43c is formed around the lower opening of the hole 43b. In this example, the cross-sectional shape of the tapered surface 43c is a truncated cone, and the size (inner diameter) of the tapered surface 43c is formed to increase as it extends downward from the hole 43b. A similar tapered surface is also formed in the hole 44b of the inner terminal 44. With this busbar unit 40A, when the conductor 28a of the coil 28 is inserted into the hole 43b from the lower side of the outer terminal 43, the tapered surface 43c can guide the tip of the conductor 28a into the hole 43b. In addition, hole 43b surrounds conductor 28a, thereby improving the degree of contact between conductor 28a and outer terminal 43. Furthermore, since the boundary between conductor 28a and outer terminal 43 is formed by a continuous line, welding can be performed along the boundary with a clean finish.

[0033] 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. [Explanation of symbols]

[0034] 1 motor, 10 shaft, 11 housing, 12, 13 bearing, 14 main body (housing main body), 14a flange, 15 cover, 16 opening, 17 opening, 18 rotor core, 19 inner periphery, 20 outer periphery, 21 connection portion, 22 magnet, 23 through hole, 24 rotor, 25 stator assembly, 26 stator core, 27 insulator, 28 coil, 28a conductor, 29 cylindrical portion, 30 teeth, 31 spokes, 32 magnetic pole portion, 33 stator, 40 busbar unit, 41 housing, 42 busbar group, 40, 40A busbar unit, 41 housing, 42, 42B busbar group, 43 terminal (outer terminal), 43a recessed groove (recessed groove), 43b hole portion, 43c tapered surface, 44 Terminal (inner terminal), 44a recessed groove (recess), 44b hole portion, 45 terminal (external terminal), 46 base, 46a recess, 46b recess, 47 cover, 48 first space, 49 second space, 50A, 50B, 50C first bus bar, 51 first portion, 51a end portion, 52 second portion, 52a end portion, 53 step portion, 54 insulating member, 60A, 60B, 60C, 60D, 60E, 60F second bus bar, 61 wall portion, x axis

Claims

1. A conducting wire forming a coil; a plurality of bus bars; The conductor wires are electrically connected to the plurality of bus bars, A motor, wherein a portion of a second bus bar among the plurality of bus bars overlaps with a step portion of a first bus bar in the axial direction.

2. The motor according to claim 1 , wherein the conductor is connected to a portion of the second bus bar.

3. The motor according to claim 1 or 2, wherein the first bus bar and the second bus bar have opposite ends in a circumferential direction.

4. the plurality of bus bars includes a third bus bar; In the radial direction, the third bus bar has a wall portion extending in the circumferential direction, The motor according to claim 1 , wherein a wall portion of the third bus bar faces the first bus bar or the second bus bar in the radial direction.

5. the first bus bar includes a terminal for connection to an external device; The motor according to claim 1 , wherein the terminals of the first bus bars are disposed adjacent to the outer periphery of the second bus bars in the radial direction.

Images