WO2020039961A1

WO2020039961A1 - Motor, electric power steering device, motor manufacturing method, bus bar unit, and bus bar unit manufacturing method

Info

Publication number: WO2020039961A1
Application number: PCT/JP2019/031362
Authority: WO
Inventors: 優太二之宮; 裕也齋藤; 敬史瀬口; 服部　隆志
Original assignee: 日本電産株式会社
Priority date: 2018-08-20
Filing date: 2019-08-08
Publication date: 2020-02-27
Also published as: JPWO2020039961A1; CN112567601B; CN112567601A

Abstract

In one embodiment of the motor disclosed in the present invention, a plurality of bus bars electrically connected to a coil wire is held by a bus bar holder. The plurality of bus bars is disposed in an overall substantially annular shape, and includes: an arc-shaped neutral point bus bar; an arc-shaped V-phase bus bar having a different axial direction position than the neutral point bus bar; and an end overlap section in which one end of the neutral point bus bar and one end of the V-phase bus bar overlap in the circumferential direction. A gap at which no bus bar is present is disposed at a position opposing the end overlap section in the radial direction.

Description

Motor, electric power steering device, method of manufacturing motor, busbar unit, and method of manufacturing busbar unit

The present invention relates to a motor, an electric power steering device, a method for manufacturing a motor, a busbar unit, and a method for manufacturing a busbar unit.

Priority is claimed on Japanese Patent Application No. 2018-154024 filed on August 20, 2018, the content of which is incorporated herein by reference.

BACKGROUND ART Conventionally, there is known a motor including a bus bar unit in which a metal bus bar and a resin bus bar holder are integrally formed by insert molding (see Patent Document 1).

Japanese Patent Laid-Open Publication No. 2010-200400

In the bus bar holder of Patent Document 1, between the U, V, and W phase side bus bars and the neutral point bus bar, two gaps without bus bars are provided on circumferential equal lines. Due to heat and cooling at the time of molding the bus bar holder, the bus bar may be deformed in the vertical direction starting from the line connecting the gaps. Due to this deformation, the positional accuracy of the connection terminals of the bus bar may be varied, or the bus bar may be cracked.

An object of the present invention is to provide a motor, an electric power steering device, a method for manufacturing a motor, a bus bar unit, and a method for manufacturing a bus bar unit, which suppress deformation of a bus bar during manufacturing.

A motor according to an exemplary embodiment of the present application includes a shaft extending along a central axis, a rotor fixed to the shaft, a stator having a conductive wire disposed radially outside the rotor, and a stator radially outside the stator. A housing is provided, a plurality of bus bars electrically connected to the conductive wires, and a bus bar holder arranged on one axial end of the stator and holding the plurality of bus bars. The plurality of busbars are arranged in a substantially annular shape as a whole, and include a first busbar having an arc shape, a second busbar having an arc shape, and an end overlapping portion. The second bus bar has a different axial position from the first bus bar. At the end overlapping portion, one end of the first bus bar and one end of the second bus bar overlap in the circumferential direction. A gap where no bus bar exists is arranged at a position radially opposed to the end overlapping portion.

In the motor according to the exemplary embodiment of the present application, the plurality of busbars are arranged in a substantially annular shape as a whole, and include a first busbar having an arc shape, a second busbar having an arc shape different from the first busbar in the axial direction, and a second busbar. An end overlap portion is provided in which one end of the first bus bar and one end of the second bus bar overlap in the circumferential direction, and a gap where no bus bar exists is disposed at a position radially opposed to the end overlap portion. The end overlapping portion resists the force acting on the bus bar due to heat and cooling during molding, and suppresses deformation of the bus bar. This suppresses the occurrence of cracks in the bus bar, stabilizes the form of the bus bar, and improves the positional accuracy of the connection terminals provided on the bus bar.

FIG. 1 is a cross-sectional view illustrating the motor according to the first embodiment. FIG. 2 is a perspective view of the bus bar unit of the first embodiment. FIG. 3 is a perspective view of the bus bar of the first embodiment. FIG. 4 is an exploded perspective view of the bus bar of FIG. FIG. 5 is a perspective view showing an end overlapping portion which is a part of the bus bar of FIG. FIG. 6A is a cross-sectional view of the bus bar unit taken along the line AA ′ in FIG. FIG. 6B is a cross-sectional view of the bus bar unit taken along the line BB ′ in FIG. FIG. 6C is a cross-sectional view of the bus bar unit taken along the line CC ′ in FIG. FIG. 6D is a cross-sectional view of the bus bar unit taken along the line DD ′ in FIG. FIG. 7 is a perspective view of a bus bar according to the second embodiment. FIG. 8 is a schematic diagram of an electric power steering device according to another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the technical idea of the present invention.

In the following description, C is the central axis of the motor. The direction in which the central axis C extends is defined as the axial direction. Further, one along the axial direction is defined as an upper side, and the other is defined as a lower side. However, the vertical direction in this specification is used for specifying a positional relationship, and does not limit an actual direction or a positional relationship. The direction of gravity is not necessarily downward. In this specification, a direction perpendicular to the rotation axis of the motor is referred to as a “radial direction”. A direction along an arc centered on the rotation axis of the motor is called a “circumferential direction”.

In the drawings used in the following description, characteristic portions may be enlarged for convenience in order to emphasize characteristic portions. Therefore, the dimensions and ratios of the components are not always the same as actual ones.

1. First embodiment

<Motor>

As shown in FIG. 1, the motor 1 includes a shaft 31, a rotor 30, a stator 40, a housing 20, and a bus bar unit 50.

The shaft 31 extends along the central axis C, and is supported by the upper bearing 71 and the lower bearing 72 so as to be rotatable around the central axis C. The rotor 30 is fixed to the shaft 31 and rotates together with the shaft 31 around the central axis C. Note that the upper bearing 71 is held by a bearing holder (not shown) located above the stator 40.

The stator 40 is disposed radially outside the rotor 30 so as to face the rotor 30. The stator 40 has a stator core 41, an insulator 42, and a coil wire 43. The insulator 42 is attached to a tooth (not shown) of the stator core 41. The coil wire 43 is an example of a conductive wire, and is wound around the teeth with the insulator 42 interposed therebetween. The coil wire 43 wound around the stator 40 is drawn out above the stator 40, and is connected to a coil connection terminal 65 shown in FIG.

The housing 20 is disposed radially outside the stator 40, and the stator 40 is fixed to the housing 20 by shrink fitting, press fitting, bonding, caulking, or the like. The housing 20 has a bottomed cylindrical shape centered on the central axis C. The housing 20 has a cylindrical portion 21 extending in the axial direction, a bottom portion 23 located at a lower end of the cylindrical portion 21, and an opening 24 opening upward. A lower bearing holder 25 that holds the lower bearing 72 is provided at the center of the bottom 23.

Note that the shape of the housing 20 is not limited to a cylindrical shape. The cross section of the housing 20 may be, for example, a polygon. Further, the housing 20 may be cylindrical, instead of having a bottom.

<Bus bar unit>

The busbar unit 50 is disposed axially above the stator 40. As shown in FIG. 2, the bus bar unit 50 includes a bus bar holder 51 and a bus bar 60.

The bus bar holder 51 is disposed at one axial end of the stator 40 and holds a plurality of bus bars 60 therein. The bus bar holder 51 is made of an insulating material such as a resin. As shown in FIG. 2, the bus bar holder 51 has an annular main body 53, a plurality of legs 55, and a connecting portion 59. The annular main body 53 covers the bus bar 60 of each phase described later. The main body 53 does not need to completely cover the bus bar 60 of each phase. As shown in FIG. 2, a plurality of windows 53a which are portions not covering the bus bar 60 may be provided on the upper surface side. The connecting portion 59 extends from the main body 53 to the opposite side of the stator 40, in the illustrated example, upward, and holds three external connection terminals 67. The connection portion 59 surrounds the rising portions of the three external connection terminals 67 excluding the tip portions. In the present embodiment, the connection portion 59 is provided at one place, but may be provided at two or more places according to the wiring of the bus bar 60. The tip of each leg 55 is inserted into a groove (not shown) formed outside the stator 40, and the position of the bus bar unit 50 with respect to the stator 40 is fixed. In addition, the tip of the leg 55 may be inserted into a groove (not shown) formed in the insulator 42 to fix the position of the bus bar unit 50.

The plurality of bus bars 60 are conductive members. As shown in FIGS. 3 and 4, the plurality of busbars 60 include an arc-shaped neutral point busbar 60n as an example of a first busbar, a V-phase busbar 60v as an example of a second busbar, and an example of a third busbar. And a U-phase bus bar 60u which is an example of the fourth bus bar.

The plurality of bus bars 60 are stacked in the bus bar holder 51 in the following predetermined arrangement.

As shown in FIG. 3, the plurality of busbars 60 are arranged in a substantially annular shape as a whole. Note that the substantially annular shape includes an incomplete annular shape in which a gap is partially formed. The V-phase bus bar 60v is arranged at a position in the axial direction different from that of the neutral point bus bar 60n, here, below the neutral point bus bar 60n. One end of the neutral-point bus bar 60n and one end of the V-phase bus bar 60v form an end overlapping portion 68 that overlaps in the circumferential direction, as shown in FIG. A gap 69 where no bus bar exists is arranged at a position radially opposed to the end overlapping portion 68. It is to be noted that the expression that the gap 69 is disposed at a position radially opposed to the end overlapping portion 68 means that the end overlapping portion 68 and the gap 69 are located on L1 shown in FIG. However, the present invention is not limited to being on a substantially equal line of a circle formed by the above, and may be on a line deviated to one of the equal lines of the circle. The gap 69 is also disposed adjacent to the other end of the neutral point bus bar 60n, that is, the end opposite to the end overlapping portion 68.

The W-phase bus bar 60w is disposed at a position in the axial direction different from that of the V-phase bus bar 60v, here, above the V-phase bus bar 60v. The circumferential position of the W-phase bus bar 60w overlaps the circumferential position of the V-phase bus bar 60v. The U-phase bus bar 60u is arranged at a position in an axial direction different from the V-phase bus bar 60v and the W-phase bus bar 60w, here, below the V-phase bus bar 60v and the W-phase bus bar 60w. The circumferential position of the U-phase bus bar 60u overlaps the circumferential position of the V-phase bus bar 60v and the W-phase bus bar 60w. The gap 69 is provided between one end of each of the V-phase bus bar 60v, the W-phase bus bar 60w, and the U-phase bus bar 60u, and the other end of the neutral point bus bar 60n.

The plurality of bus bars 60 and the bus bar holder 51 are formed by insert molding. The insulating material of the bus bar holder 51 is interposed in the gap 69. The insulating material of the main body 53 of the bus bar holder 51 is interposed between the stacked bus bars 60 in the axial direction so as not to contact each other. As shown in FIG. 6A, in the cross section of the bus bar unit 50 at the position of AA ′ in FIG. 3, a neutral point bus bar 60n is arranged. As shown in FIG. 6B, in the cross section of the bus bar unit 50 at the position of BB ′ in FIG. 3, the V-phase bus bar 60v is disposed axially below the neutral point bus bar 60n. As shown in FIG. 6C, in the cross section of the bus bar unit 50 at the position of CC ′ in FIG. 3, the U-phase bus bar 60u is disposed axially below the V-phase bus bar 60v. As shown in FIG. 6D, in the cross section of the bus bar unit 50 at the position of DD ′ in FIG. 3, the W-phase bus bar 60w is disposed axially above the V-phase bus bar 60v, and the V-phase bus bar 60v A U-phase bus bar 60u is arranged axially below.

As shown in FIGS. 3 and 4, the neutral-point bus bar 60n, the U-phase bus bar 60u, the V-phase bus bar 60v, and the W-phase bus bar 60w each have a plurality of coil connections connected to the coil wire 43. The terminal 65 is provided. The coil connection terminal 65 is an example of a conductive wire connection terminal, is arranged along the circumferential direction of each bus bar 60, and protrudes radially outward from the bus bar 60 arranged annularly. The V-phase bus bar 60v, the W-phase bus bar 60w, and the U-phase bus bar 60u each have

external connection terminals

67v, 67w, and 67u at one end. The

external connection terminals

67v, 67w, and 67u extend on the opposite side to the stator 40, that is, upward in the axial direction, and are electrically connected to an external power supply (not shown).

<Bus bar unit manufacturing method>

In manufacturing the bus bar unit 50 shown in FIG. 2, a plurality of metal bus bars 60 are inserted into a mold (not shown) in a predetermined arrangement, and a resin is injected into the mold. The bus bar holder 51 integrally formed with the plurality of bus bars 60 is taken out. In a predetermined arrangement, the plurality of busbars 60 are arranged in a substantially annular shape as a whole, and arcuate V-phase busbars 60v are arranged at axially lower positions with respect to arcuate neutral point busbars 60n. An end overlap portion 68 is formed by overlapping one end of the neutral point bus bar 60n and one end of the V-phase bus bar 60v in the circumferential direction, and the bus bar 60 exists at a position radially opposed to the end overlap portion 68. Gap 69 is formed. In a predetermined arrangement, W-phase bus bar 60w is arranged at a position axially above V-phase bus bar 60v. The circumferential position of the W-phase bus bar 60w overlaps the circumferential position of the V-phase bus bar 60v. The U-phase bus bar 60u is arranged at a position axially below the V-phase bus bar 60v and the W-phase bus bar 60w. The circumferential position of the U-phase bus bar 60u overlaps the circumferential position of the V-phase bus bar 60v and the W-phase bus bar 60w.

<Motor manufacturing method>

In the manufacture of the motor 1 shown in FIG. 1, the bus bar unit 50 manufactured by the above-described method is arranged at one axial end of the stator 40. At this time, the tip of the leg 55 of the bus bar holder 51 is inserted into the groove of the stator 40 or the groove of the insulator 42 to fix the position of the bus bar unit 50. The coil wire 43 of the stator 40 is connected to a coil connection terminal 65 projecting radially outward of the bus bar holder 51 as shown in FIG. The stator 40 to which the bus bar unit 50 is connected is inserted into the housing 20. The stator 40 is fixed to the housing 20 by shrink fitting, press fitting, bonding, caulking, or the like. The rotor 30 is inserted inside the stator 40 in the radial direction.

As described above, in the motor 1 and the method of manufacturing the same according to the first embodiment, the plurality of busbars are arranged in a substantially annular shape as a whole, and have an arc-shaped neutral point busbar 60n and a neutral point busbar 60n. An arc-shaped V-phase bus bar 60v having a different axial position, and an end overlapping portion 68 in which one end of the neutral point bus bar 60n and one end of the V-phase bus bar 60v overlap in the circumferential direction are included. A gap 69 where no bus bar exists is arranged at a position radially opposed to the end overlapping portion 68. In the arrangement of the plurality of bus bars 60, if there are two gaps, the bus bars 60 arranged annularly along the axial direction starting from the line connecting the two gaps due to heat and cooling during molding of the bus bar unit 50. May be deformed. In the arrangement of the plurality of bus bars 60 according to the present embodiment, one gap 69 is provided, and an end overlapping portion 68 in which ends of the bus bar 60 are circumferentially overlapped with each other at a position radially opposed to the gap 69. Provide. Since the end overlapping portion 68 can oppose the force acting toward the starting point due to heat and cooling at the time of molding the bus bar unit 50, the deformation of the bus bar 60 is suppressed. This suppresses the occurrence of cracks in the bus bar 60, stabilizes the overall configuration of the bus bar 60, and improves the positional accuracy of the coil connection terminals 65 and the external connection terminals 67 arranged at predetermined intervals on the outer periphery of the bus bar 60. .

2. Second embodiment

Hereinafter, the same components as those of the motor 1 according to the first embodiment will be denoted by the same reference numerals, and detailed description will be omitted.

FIG. 7 shows a configuration of a plurality of bus bars 260 according to the second embodiment. Of the bus bars 260, the neutral point bus bar 60n has an end extension 268 at a position radially opposed to the end overlap 68. The end extension 268 extends in the circumferential direction beyond L1, which is a substantially equal line of a circle formed by the bus bar 260. Due to the presence of the end extension 268, the gap 69 where no bus bar exists is smaller than the gap 69 according to the first embodiment.

Due to the presence of the end overlapping portion 68 and the end extending portion 268, both ends in the circumferential direction of the neutral point bus bar 60n project beyond L1. For this reason, deformation of the bus bar 260 due to heat and cooling during molding of the bus bar unit is further suppressed.

3. Other embodiments

Hereinafter, the same components as those of the motor 1 according to the first and second embodiments will be denoted by the same reference numerals, and detailed description will be omitted.

(1)

The number of

bus bars

60 and 260 and the arrangement of each phase are not limited to the above example. The number of the bus bars 60 and 260 can be adjusted according to the number of phases of the motor 1. The second bus bar forming the end overlapping portion 68 together with one end of the neutral point bus bar 60n may be a W-phase bus bar or a U-phase bus bar. The axial arrangement and circumferential positions of the V-phase busbar, the W-phase busbar, and the U-phase busbar can also be changed.

(2)

<Electric power steering device>

An example in which the motor 1 is mounted on the electric power steering device 2 will be described with reference to FIG.

The electric power steering device 2 is mounted on a steering mechanism of a wheel 912 of an automobile. The electric power steering device 2 is a column-type electric power steering device that directly reduces the steering force by the power of the motor 1. The electric power steering device 2 includes the motor 1, a steering shaft 914, and an axle 913.

The steering shaft 914 transmits an input from the steering 911 to an axle 913 having wheels 912. The power of the motor 1 is transmitted to the axle 913 via a ball screw. The motor 1 employed in the column-type electric power steering device 2 is provided inside an engine room (not shown). Although the electric power steering device 2 shown in FIG. 8 is a column type, it may be a rack type.

The electric power steering device 2 includes a motor 1. For this reason, the electric power steering device 2 having the same effects as the above embodiment can be obtained.

Here, the electric power steering device 2 is described as an example of a method of using the motor 1, but the method of using the motor 1 is not limited, and the motor 1 can be used in a wide range such as a pump and a compressor.

The above-described embodiments and modifications are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Electric power steering apparatus, 20 ... Housing, 21 ... Cylindrical part, 23 ... Bottom part, 24 ... Opening part, 25 ... Lower bearing holder, 30 ... Rotor, 31 ... Shaft, 40 ... Stator, 41 ... Stator core, 42 insulator, 43 coil wire, 50 busbar unit, 51 busbar holder, 53 body part, 53a window part, 55 leg part, 59 connection part, 60, 260 busbar, 60n middle Bus bar for sex point, 60u ... bus bar for U phase, 60v ... bus bar for V phase, 60w ... bus bar for W phase, 65 ... coil connection terminal, 67, 67v, 67w, 67u ... external connection terminal, 68 ... end overlapping part 69, gap, 71 upper bearing, 72 lower bearing, 268 end extension, 911 steering, 912 wheels, 913 axle, 14 ... steering axis, C ... central axis

Claims

A shaft extending along a central axis;

A rotor fixed to the shaft,

A stator disposed radially outside the rotor and having a conductive wire;

A housing disposed radially outside the stator;

A plurality of busbars electrically connected to the conductive line;

A busbar holder arranged on one axial side of the stator and holding the plurality of busbars,

The plurality of busbars are arranged in a substantially annular shape as a whole,

An arc-shaped first bus bar;

An arc-shaped second bus bar having a different axial position from the first bus bar;

An end overlapping portion in which one end of the first bus bar and one end of the second bus bar overlap in a circumferential direction,

A motor in which a gap without a bus bar is arranged at a position radially opposed to the end overlapping portion.
The bus bar and the bus bar holder are integrally molded products,

The busbar holder is made of an insulating material,

The motor according to claim 1, wherein the insulating material is interposed in the gap.
The motor according to claim 2, wherein the insulating material is interposed between the plurality of bus bars in an axial direction.
The first bus bar is a neutral point bus bar,

The second bus bar is one of a U-phase bus bar, a V-phase bus bar, and a W-phase bus bar,

The motor according to any one of claims 1 to 3, wherein the gap is disposed adjacent to the other end of the first bus bar.
The plurality of bus bars,

A third bus bar having a different axial position from the second bus bar and overlapping the second bus bar in a circumferential direction;

A fourth bus bar having a different axial position from the second bus bar and the third bus bar and overlapping at least one of the second bus bar and the third bus bar in a circumferential direction;

Further comprising

The third bus bar is a bus bar for a phase different from the second bus bar among U phase, V phase, and W phase.

The fourth bus bar is a bus bar for a phase different from the second bus bar and the third bus bar among U phase, V phase, and W phase.

5. The gap according to claim 4, wherein the gap is provided between one of the one end of the second bus bar, the one end of the third bus bar, and the one end of the fourth bus bar, and the other end of the first bus bar. Motor.
6. The motor according to claim 5, wherein the second bus bar, the third bus bar, and the fourth bus bar each have, at the one end, an external connection terminal that extends in an axial direction toward a side opposite to the stator. 7.
Each of the plurality of bus bars has a plurality of conductive line connection terminals connected to the conductive line,

The motor according to any one of claims 1 to 6, wherein the plurality of conductive line connection terminals are arranged along a circumferential direction of each bus bar, and protrude radially outward of each bus bar.
An electric power steering device comprising the motor according to claim 1.
A shaft extending along a central axis, a rotor fixed to the shaft, a stator around which a conductive wire is wound via an insulator, a housing disposed radially outside the stator, A plurality of bus bars connected to the, and a bus bar holder arranged on one axial end side of the stator and holding the plurality of bus bars, comprising:

Insert a plurality of metal bus bars into the mold with a predetermined arrangement,

Inject resin into the mold,

Take out the bus bar holder integrally molded with the bus bar,

By inserting the leg of the bus bar holder into the groove of the stator or the groove of the insulator, the bus bar holder is arranged at one axial end of the stator,

Connecting the conductive wire of the stator to a bus bar held by the bus bar holder,

Inserting the stator into the housing;

Inserting the rotor radially inward of the stator, including the step of:

Arranging the plurality of busbars in a substantially annular shape,

Disposing an arc-shaped second bus bar having a different axial position from the arc-shaped first bus bar;

Forming an end overlapping portion in which one end of the first bus bar and one end of the second bus bar overlap in the circumferential direction;

Forming a gap without a bus bar at a position radially opposed to the end overlapping portion.
A plurality of bus bars electrically connected to the conductive line;

A bus bar holder that holds the bus bar,

The plurality of busbars are arranged in a substantially annular shape as a whole,

An arc-shaped first bus bar;

An arc-shaped second bus bar having a different axial position from the first bus bar;

An end overlapping portion in which one end of the first bus bar and one end of the second bus bar overlap in a circumferential direction,

A busbar unit including: a gap in which no busbar exists, which is radially opposed to the end overlapping portion.
A method for manufacturing a bus bar unit in which a bus bar and a bus bar holder are integrally formed,

Insert a plurality of metal bus bars into the mold with a predetermined arrangement,

Inject resin into the mold,

Removing the bus bar holder integrally formed with the bus bar, including the step, wherein the predetermined arrangement includes:

Arranging the plurality of busbars in a substantially annular shape,

Disposing an arc-shaped second bus bar having a different axial position from the arc-shaped first bus bar;

Forming an end overlapping portion in which one end of the first bus bar and one end of the second bus bar overlap in the circumferential direction;

A method of manufacturing a bus bar unit, comprising: forming a gap without a bus bar at a position radially opposed to the end overlapping portion.