WO2008059736A1

WO2008059736A1 - Brushless motor

Info

Publication number: WO2008059736A1
Application number: PCT/JP2007/071609
Authority: WO
Inventors: Tatsuya Sato; Eiichi Machida; Yoshihiro Nishimura; Atsushi Okamoto; Hirotatsu Ikeno; Yoshihisa Haruishi
Original assignee: Mitsuba Corporation
Priority date: 2006-11-15
Filing date: 2007-11-07
Publication date: 2008-05-22
Also published as: JP5059021B2; JPWO2008059736A1

Abstract

A brushless motor (1) is provided with a magnet holding section (52) for holding/fixing a magnet, and a magnet holder (51) having a resolver rotor connecting section (54) connected to a resolver rotor (35). The resolver rotor connecting section (54) and the resolver rotor (35) are coupled with each other by a resolver coupling section (63). The resolver coupling section (63) is composed of a resolver rotor connecting piece (57), which is formed at the resolver rotor connecting section (54), and a fitting groove (66), which is formed on the resolver rotor (35). In a fitting groove (66), a fitting claw (59) of the resolver rotor connecting piece (57) is fitted with pressure and fixed, and the resolver rotor (35) and the magnet holder (51) are connected in a prescribed angular position relation. A rotor shaft (22) is provided with a flange section (64) for preventing removal of the resolver rotor (35).

Description

Specification

Brushless motor technology

TECHNICAL FIELD [0001] The present invention relates to a brushless motor used in an electric power steering apparatus and the like, and more particularly to a structure of a magnet holder that holds a rotor magnet.

Background art

In order to assist the steering force of automobiles and the like, many vehicles have been equipped with so-called power steering devices in recent years. As such power steering devices, in recent years, vehicles equipped with electric power steering devices (so-called electric power steering devices) are increasing from the viewpoint of reducing engine load and weight. In this electric power steering device (hereinafter abbreviated as EPS), the motor, which is the driving source, is required to be smaller and have higher performance due to the arrangement of the device in a narrow bonnet space. Conventionally, as such a motor, a brushed DC motor has been used in many cases, and nowadays, with the improvement of control technology, a brushless motor that is superior in terms of miniaturization and high performance has been developed. Adoption is increasing

On the other hand, in a brushless motor, in order to rotationally drive the rotor, it is necessary to detect the rotational position of the rotor and sequentially excite the stator side coil (stator coil) based on the detected rotor rotational position. For detecting the rotational position of the rotor, detection devices using encoders, hole ICs, etc. have been used. In recent years, due to the demand for higher performance and lower noise in brushless motors, sensors with high resolution are also required for rotational position detection, and the use of resolvers, one of non-contact rotational sensors, is increasing. Resolvers have a simple structure that is resistant to high temperatures and vibration environments and are less likely to break down. Therefore, the use of resolvers in in-vehicle motors, especially EPS, is increasing.

[0004] When this resolver is used, it is required to detect the rotor rotational position with high accuracy. In order to improve the resolver accuracy, it is important that the motor circuit and the magnetic circuit of the resolver are synchronized. And in order for both magnetic circuits to synchronize, the positional accuracy between a motor part and a resolver is important. Therefore, the position accuracy between the motor and resolver is determined. High accuracy is required for the positional relationship between the resolver rotor and the rotor magnet of the motor portion. In particular, from the viewpoint of cost reduction, in the type of motor using a segment magnet for the rotor, it is necessary to first position the magnet with respect to the rotor core, and a magnet holder that also serves to fix the magnet is used.

FIG. 7 is an explanatory diagram showing a schematic configuration of a rack shaft type EPS motor. As shown in FIG. 7, the magnet 101 is attached to a rotor core 103 that is press-fitted and fixed to the shaft 102. A magnet holder 104 is fixed to the rotor core 103. The magnet 101 is held and fixed to the outer peripheral surface of the rotor core 103 by the magnet holder 104. On the other hand, the resolver rotor 105 is usually fixed to the shaft 102. Spacers 106 and 107 are disposed on both sides of the resolver rotor 105 in the axial direction to prevent the resolver rotor 105 from coming off in the axial direction. Each spacer 106, 107 is fixed to the shaft 102. The resolver rotor 105 is prevented from coming off in the axial direction by the spacers 10 6 and 107.

[0006] Positioning of the resolver rotor in the rotational direction is performed by providing positioning indexes P on the shaft 102, the spacer 106, and the resolver rotor 105, and combining them. That is, first, the spacer 106 is press-fitted into the shaft 102 while matching the indices P with each other. Next, the spacer 106 and the index P of the resolver rotor 105 are aligned, and the resolver rotor 105 is bonded and fixed to the shaft 102. Further, a spacer 107 is press-fitted into the shaft 102, and the resolver rotor 105 is sandwiched between the spacers 106 and 107 to prevent axial removal.

In this case, the positioning index P provided on the shaft 102 indicates the reference position of the rotor. Therefore, with this index P as a reference, the rotor core 103 is fixed to the shaft 102 and the magnet holder 104 is fixed to the rotor core 103. Further, the positioning index P of the resolver rotor 105 also indicates the reference position as a single resolver. Therefore, by attaching the magnet holder 104 to the resolver rotor 105 so as to match the index P, the magnet 101 held and fixed to the magnet holder 104 and the resolver rotor 105 are positioned and fixed in a predetermined angular positional relationship. As a result, the magnetic circuit of the motor unit and the resolver are synchronized, and the rotor rotational position using the resonance lever can be detected.

Patent Document 1: Japanese Patent Laid-Open No. 2006-87277

Patent Document 2: JP-A-2005-20887 Disclosure of the invention

Problems to be solved by the invention

[0008] However, in the case of the motor configuration as described above, two spacers are required for mounting the resolver rotor. For this reason, there is a problem that the number of parts increases, resulting in an increase in cost. In addition, high dimensional accuracy is required for each component in order to increase the positional accuracy between the motor part and the resolver. In particular, in the case of a configuration with a large number of parts, the assembling process is increased, and a high assembling accuracy is required each time, and there is a problem that it is disadvantageous in terms of cost.

[0009] Furthermore, when assembling each part, there is a problem that the assembling accuracy is lowered because the work is performed visually with reference to the positioning index. In addition, there was a problem that it was a hindrance to the improvement of mass productivity because of the manual work by visual inspection. In particular, in the case of a configuration with a large number of parts, assembly errors accumulate, and the work man-hours that make it difficult to improve the positional accuracy between the motor part and the resolver also increase. For this reason, there is a problem in that it increases the rotor position detection accuracy and reduces manufacturing costs, and there has been a need for improvement.

An object of the present invention is to improve the positional accuracy between a motor portion and a resolver while reducing the number of parts around the resolver rotor in a brushless motor using a resolver.

Means for solving the problem

[0011] The brushless motor of the present invention includes a stator core, a stator including a coil wound around the stator core, a rotor shaft that is rotatably arranged with respect to the stator, and a rotor core fixed to the rotor shaft. A resolver including: a rotor provided with a magnet attached to an outer periphery of the rotor core; a resolver rotor attached to the rotor shaft; and a resolver stator disposed outside the resolver rotor; and attached to the rotor And a magnet holder having a magnet holding part for holding and fixing the magnet on the outer periphery of the rotor core, and a resolver rotor connecting part connected to the resolver rotor.

[0012] In the present invention, a magnet holding part for holding and fixing a magnet to a brushless motor having a stator, a rotor and a resolver, and a resolver port connected to the resolver rotor By providing a magnet holder provided with a data connector, the magnet and the resolver rotor can be mechanically connected in a predetermined angular positional relationship. For this reason, the positioning accuracy between the magnet and the resolver rotor is improved as compared with the method in which the index is visually adjusted. In addition, since no visual work is required, the assembly workability is improved and the man-hours can be reduced accordingly.

[0013] In the brushless motor, a resolver coupling portion that couples the resolver rotor connection portion and the resolver rotor may be provided between the resolver rotor connection portion and the resolver rotor. In this case, the resolver coupling portion is provided with a resolver rotor connecting piece formed in the resolver rotor connecting portion and extending in the axial direction, and a fitting portion formed in the resolver rotor and into which the resolver rotor connecting piece is fitted. Also good. Further, the resolver port connecting piece and the magnet are set in a predetermined angular positional relationship, and the fitting portion and the convex portion formed on the outer periphery of the resolver rotor are set in a predetermined angular positional relationship. Also good.

[0014] In addition, a flange portion that abuts the resolver rotor on the rotor shaft and restricts the movement of the resolver rotor in the axial direction may be provided. This prevents the resolver rotor force S flange from coming off and eliminates the need for spacers on the rotor shaft, thereby reducing the number of parts and assembly steps.

On the other hand, the resolver rotor connecting portion and the magnet holding portion may be provided so as to be separable. As a result, when the specification is changed, such as changing the energization timing, the change can be made only by changing the resolver rotor connecting portion without changing the magnet holding portion. This eliminates the need for large and complex new molds, and allows flexible support for many vehicle body lineups with less expensive parts. In this case, a holder joint portion for joining the resolver rotor connection portion and the magnet holding portion may be provided between the resolver rotor connection portion and the magnet holding portion. The holder joint may be provided with a fitting piece formed in the resolver rotor connecting portion and extending in the axial direction, and a fitting portion formed in the magnet holding and fitted with the fitting piece.

The invention's effect

[0016] According to the brushless motor of the present invention, in the brushless motor including the stator, the rotor, and the resolver, the magnet holding portion that holds and fixes the magnet and the resolver rotor are in contact with each other. Since the magnet holder is provided with the connected resolver rotor connection part, the magnet and resolver rotor can be mechanically connected in a predetermined angular positional relationship, and the magnet and resolver rotor can be accurately connected. Can be positioned. In addition, since no visual work is required, the assembly workability is improved, and the man-hours can be reduced correspondingly, and the manufacturing cost can be reduced.

[0017] Further, by providing the rotor shaft with a flange portion that restricts the movement of the resolver rotor in the axial direction, the resolver rotor is prevented from coming off by the flange portion, and there is no need to arrange a spacer on the rotor shaft. As a result, the number of parts and assembly man-hours can be reduced. In addition, since the dimensional accuracy of the portion where the spacer of the rotor shaft is fixed is relaxed, the manufacturing cost of the rotor shaft can be reduced.

[0018] Furthermore, by providing the resolver rotor connecting portion and the magnet holding portion in a separable manner, it is possible to change the specification, such as changing the conduction timing, only by changing the resonance lever rotor connecting portion without changing the magnet holding portion. It becomes possible. For this reason, even when manufacturing a new mold, it is sufficient to use only the magnet holding part, and it is possible to flexibly add to a large body lineup with cheaper parts that do not require the production of a large and complex new mold. It is possible to respond.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a configuration of a brushless motor that is Embodiment 1 of the present invention.

FIG. 2 is a perspective view of a magnet holder.

[Fig. 3] (a) is a cross-sectional view of the magnetic honoreda along the AA spring in (b), and (b) is a right side view of the magnetic honoreda.

[FIG. 4] (a) is a side view of the resolver rotor, and (b) is a sectional view thereof.

FIG. 5 shows a configuration of a magnet holding portion of a brushless motor that is Embodiment 2 of the present invention, in which (a) is a sectional view thereof and (b) is a side view.

FIG. 6 shows a configuration of a magnet holding part of a brushless motor that is Embodiment 2 of the present invention, where (a) is a front view thereof, (b) is a left side view, and (c) is a right side view. is there.

FIG. 7 is an explanatory diagram showing a schematic configuration of a rack shaft type EPS motor.

Explanation of symbols Brushless motor 2 rack car

Ball screw mechanism 11 Stator

13 Stator core

15 Insulator

a Insulator 16 Terminano Reuni

Coil feed terminal 18 External connection terminal

Lead wire 21 Rotor

Low 23 rotor core

25 Magnet cover

32 bearings

34 Resolver stator

36 coils

42 Natsu Isobe

Screw part 44 Bonore

Angular bearing 46a, 46b Bearing fixing ring Step 48 Bearing fixing ring Step 51 Magnet Honoreda

Magnet holder 53 Rotor shaft fixing part a surface 54 Resolver rotor connection part

Base 56 Honoreda Arm

Resolver rotor connection piece 58 Base piece

Mating claw 61 taper

Convex part 63 Resolver coupling part

65 Shaft through hole

Fitting groove (fitting part)

73 Magnet holder

75 Holder joint

^: Source 77 Honoreda Arm 78 Shaft through hole 79 Mating groove

81 Mating piece 101 Magnet

102 Shaft 103 Rotor core

104 Magnet holder 105 Resolver rotor

106 Spacer 107 Spacer

P Positioning index

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a brushless motor that is Embodiment 1 of the present invention. The motor 1 shown in FIG. 1 is used as a power source for rack-assisting EPS and has a configuration in which the rack shaft 2 passes through the motor 1. The rotation of the motor 1 is transmitted to the rack shaft 2 via the ball screw mechanism 3 and becomes a steering assist force. The motor 1 has an inner rotor type device configuration in which a stator 11 is disposed outside and a rotor 21 is disposed inside. A resolver 33 is used to detect the rotational position of the rotor 21.

Stator 11 includes a housing 12 and a stator core fixed to the inner peripheral side of housing 12

13 and a coil 14 wound around the stator core 13. The housing 12 is made of iron or the like. An aluminum die-cast housing 41 is attached to the left end of the housing 12 in the figure. The stator core 13 has a structure in which many steel plates are laminated. A plurality of (in this case, nine) teeth are projected from the inner peripheral side of the stator core 13. A coil 14 is wound around a slot (9 slots) formed between the teeth via an insulator 15 made of synthetic resin.

Insulators 15 are attached to both ends of the stator core 13. A terminal unit 16 is attached to the left end of the left side (insulator 15a) of the insulator 15 in FIG. The terminal unit 16 has a large number of coil feeding terminals 17 protruding in the radial direction. Each coil feeding terminal 17 is connected to a terminal portion of the coil 14 (a winding start portion or a winding end portion of the coil 14)! Terminal Unit The external connection terminal 18 that is electrically connected to the coil power supply terminal 17 is further provided on the connector 16. A lead wire 19 is connected to the external connection terminal 18. Each coil 14 is appropriately supplied with electric power via a terminal unit 16 from a lead wire 19 connected to an external power source.

The rotor 21 is arranged inside the stator 11. The rotor 21 has a configuration in which a cylindrical rotor shaft 22, a rotor core 23, a magnet 24, and a magnet cover 25 are arranged coaxially. A rack shaft 2 is passed through the rotor shaft 22. A cylindrical rotor core 23 is externally mounted on the outer periphery of the rotor shaft 22. A magnet 24 having a 6-pole configuration is held and fixed on the outer periphery of the rotor core 23 by a magnet holder 51 made of synthetic resin. 2 is a perspective view of the magnet holder 51, FIG. 3 (a) is a cross-sectional view of the magnet holder 51 along the line AA in FIG. 3 (b), and FIG. 2 (b) is a right side view of the magnet holder 51.

As shown in FIGS. 2 to 4, the magnet holder 51 includes a magnet holding part 52, a rotor shaft fixing part 53, and a resolver rotor connection part 54. The magnet holding part 52 is provided with a base part 55 that is fixed to the rotor shaft 22 together with the rotor shaft fixing part 53, and a holder arm 56 that is formed to project from the base part 55 in the axial direction. The holder arm 56 has a cantilever structure extending in the axial direction from one end side of the base portion 55. The holder arm 56 has a substantially T-shaped cross section. Between the adjacent holder arms 56, the magnet 24 is press-fitted from the axial direction to the free end side of the holder arm 56 (left end side in FIG. 3). As a result, the magnet 24 is held and fixed between the outer peripheral surface of the rotor core 23 and the holder arm 56. After the magnet 24 is attached, the magnet cover 25 is externally attached to the outside of the magnet honoreda 51. As a result, the magnet 24 is pressed from the radial direction, and the movement of the magnet 24 in the axial direction is restricted (prevention from coming off).

The rotor shaft fixing portion 53 is formed in a cylindrical shape, and is formed integrally with the base portion 55. The inner diameter of the rotor shaft fixing portion 53 is formed slightly smaller than the outer diameter of the rotor shaft 22. The magnet holder 51 is press-fitted and fixed to the outer periphery of the rotor shaft 22 by the rotor shaft fixing portion 53.

A resolver rotor connecting piece 57 connected to the resolver rotor 35 of the resolver 33 is provided at the end of the rotor shaft fixing portion 53 (the right end side in FIG. 1 and the upper end side in FIG. 2). Yes. The resolver rotor connecting pieces 57 are formed so as to protrude from the end of the rotor shaft fixing portion 53 in the axial direction, and are formed in three equal portions in the circumferential direction. The resolver rotor connecting piece 57 has a predetermined angular positional relationship with the magnet 24 held and fixed to the magnet holding portion 52. The resolver rotor connecting piece 57 includes a base piece portion 58 projecting from the end surface 53a of the rotor shaft fixing portion 53, and a fitting claw 59 projecting further in the axial direction from the base piece portion 58. Yes. The fitting claw 59 has a smaller circumferential dimension than the base piece 58. Further, a tapered portion 61 is formed at the distal end portion of the fitting claw 59.

[0029] A housing 31 made of aluminum die casting is attached to the right end side of the housing 12 in the figure. The housing 31 accommodates a bearing 32 that supports the right end side of the rotor 21 and a resolver 33 that detects the rotation of the rotor 21. The resolver 33 includes a resolver stator 34 fixed to the housing 31 side and a resolver rotor 35 fixed to the rotor 21 side. A coil 36 is wound around the resolver stator 34, and an excitation coil and a detection coil are provided.

A resolver rotor 35 fixed to the rotor shaft 22 is disposed inside the resolver stator 34. 4A is a side view of the resolver rotor 35, and FIG. 4B is a cross-sectional view thereof. As shown in FIG. 4 (b), the resonance lever rotor 35 has a structure in which metal plates are laminated, and convex portions 62 are formed in three directions. When the rotor shaft 22 rotates, the resolver rotor 35 also rotates in the resolver stator 34. The excitation coil of the resolver stator 34 is given a high frequency signal, and the phase of the signal output from the detection coil changes due to the proximity of the convex portion 62. The rotation position of the rotor 21 is detected by comparing this detection signal with the reference signal. Then, based on the rotational position of the rotor 21, the current to the coil 14 is appropriately switched, and the rotor 21 is rotationally driven.

[0031] Here, in the conventional brushless motor, as described above, the resolver rotor is attached by visual inspection, and a spacer is arranged before and after that to prevent it from falling out. There was also a problem in work efficiency. On the other hand, in the motor 1 according to the present invention, the resolver coupling portion 63 that couples the magnet holder 51 and the resolver rotor 35 is provided between the magnet holder 51 and the resolver rotor 35 so that the resolver rotor 35 can be positioned with high accuracy. ing. Also, the rotor shaft 22 has a flange portion 64, which does not use a spacer. In addition, the resolver rotor 35 can be prevented from coming off.

As shown in FIG. 4 (a), the resolver rotor 35 is formed with a shaft through hole 65 through which the rotor shaft 22 is passed. A fitting groove (fitting portion) 66 is notched in the shaft through hole 65 along the axial direction. The fitting grooves 66 correspond to the resolver rotor connecting piece 57 and are arranged in three equal places in the circumferential direction. The resolver rotor connecting piece 57 and the fitting groove 66 form a resolver coupling portion 63. Further, the fitting groove 66 is formed so as to have a predetermined angular positional relationship with the convex portion 62 of the resolver rotor 35. The dimension in the circumferential direction of the fitting groove 66 is slightly smaller than the dimension in the circumferential direction of the fitting claw 59, and the fitting claw 59 is attached so as to be lightly press-fitted into the fitting groove 66.

On the other hand, as shown in FIG. 1, a flange portion 64 is formed near the right end of the rotor shaft 22. The flange portion 64 is formed with a larger diameter than other portions of the rotor shaft 22. When the resolver rotor 35 is attached to the rotor shaft 22, one end side of the resolver rotor 35 comes into contact with the flange portion 64. Thereby, the movement of the resolver rotor 35 in the axial direction is restricted, and the resolver rotor 35 is prevented from coming off on the rotor shaft 22 in the axial direction.

In the motor 1 having such a configuration, first, the resolver rotor 35 is attached to the rotor shaft 22. The resolver rotor 35 is attached in such a manner that the rotor shaft 22 is inserted into the shaft through hole 65 and the resolver rotor 35 is press-fitted into the rotor shaft 22. The resolver rotor 35 is press-fitted to a position where it abuts on the flange portion 64. Thereafter, the magnet holder 51 is press-fitted and fixed to the rotor shaft 22. At this time, the fitting claw 59 of the resolver rotor connecting piece 57 is lightly press-fitted into the fitting groove 66 of the resolver rotor 35.

The fitting claw 59 has a predetermined angular positional relationship with respect to the magnet 24 held and fixed to the magnet holder 51. Further, the fitting groove 66 has a predetermined angular position relationship with the convex portion 62 of the resolver rotor 35. Therefore, by attaching the fitting claw 59 to the fitting groove 66, the magnet 24 and the resolver rotor 35 are connected in a predetermined angular positional relationship. That is, the positional relationship between the magnet 24 and the resolver rotor 35 is mechanically set by the fitting claw 59 and the fitting groove 66. For this reason, in the motor 1, the positioning accuracy can be dramatically improved as compared with the method in which the index is visually adjusted. No visual work required Therefore, the assembly workability is also improved, and the man-hours can be reduced accordingly.

[0036] Further, since the circumferential positioning of the magnet 24 and the resolver rotor 35 is performed with high precision, the adjustment angle force S of the resolver stator 34 at the time of final position adjustment of the resolver 33 is reduced, and the resolver 33 Adjustment work becomes easy. Further, the long hole provided for adjusting the resolver can be made small, and the dimensions of the long hole forming bracket and the like can be reduced. Since the bracket for forming the long hole is in a position where it can easily interfere with other parts in the motor, it is preferable that this portion be as small as possible. Therefore, if the circumferential dimension of the long hole is reduced and the bracket is made smaller, a corresponding space will be created, improving the layout in the motor and reducing the overall size of the motor. It becomes possible.

The resolver rotor 35 is attached on the rotor shaft 22 so as to be sandwiched between the flange portion 64 and the base piece portion 58 of the resolver rotor connecting piece 57. Therefore, the motor 1 can prevent the resolver rotor 35 from coming off in the axial direction without using a special spacer. For this reason, the number of parts can be reduced as compared with the conventional brushless motor, and the spacer assembly work is not required, so that the productivity can be improved and the cost can be reduced. Furthermore, since the dimensional accuracy of the portion where the spacer of the rotor shaft 22 is fixed is relaxed, the cost can be reduced accordingly.

[0038] In addition, the weight and inertia of the spacer can be reduced, the motor can be reduced in weight, and the control response can be improved. For this reason, the product value as an EPS motor is also improved. In addition, the removal of the stopper by the spacer makes it possible to assemble the resolver rotor 35, magnet holder 51, rotor core 23, etc. from the same direction with respect to the rotor shaft 22, which also improves workability. It is done. Since the outer dimension accuracy of the flange portion 64 may be relatively rough, the cost reduction due to the dimensional accuracy relaxation of the spacer fixing portion is greater than the cost increase associated with the formation of the flange portion 64.

A housing 41 is attached to the left end side of the housing 12. A ball screw mechanism 3 is incorporated in the housing 41. The ball screw mechanism 3 includes a nut part 42, a screw part 43 formed on the outer periphery of the rack shaft 2, and a large number of balls 44 interposed between the nut part 42 and the screw part 43. ing. The rack shaft 2 is supported so as to reciprocate in the left-right direction by the nut portion 42 in a state where rotation around the shaft is restricted. It moves in the left-right direction with the rotation of.

[0040] The nut portion 42 is fixed to the left end portion of the rotor shaft 22, and is rotatably held by an angular bearing 45 fixed to the housing 41. The angular bearing 45 is in a state where the axial movement is restricted between the bearing fixing rings 46a and 46b screwed into the opening of the housing 41 and the step 47 formed inside the housing 41. It is fixed. The axial movement between the nut portion 42 and the angular bearing 45 is caused by a bearing fixing ring 48 screwed into the left end of the nut portion 42 and a step portion 49 formed on the outer periphery of the nut portion 42. Be regulated.

[0041] In an EPS equipped with such a motor 1, the steering handle is first operated to rotate the steering shaft, and the rack shaft 2 is moved in a direction corresponding to the rotation to perform a steering operation. When a steering torque sensor (not shown) is activated by this operation, electric power is supplied from the knotter to the coil 14 via the lead wire according to the detected torque. When electric power is supplied to the coil 14, the motor 1 operates and the rotor shaft 22 rotates. When the rotor shaft 22 rotates, the nut portion 42 coupled therewith rotates, and the axial assisting force is transmitted to the rack shaft 2 by the action of the ball screw mechanism 3. Thereby, the movement of the rack shaft 2 is promoted, and the steering force is assisted.

Example 2

Next, a brushless motor that is Embodiment 2 of the present invention will be described. The brushless motor 71 of the second embodiment (hereinafter abbreviated as “motor 71”) has the same basic configuration as the motor 1 of the first embodiment, but the magnet holder 72 has a divided structure, which improves design flexibility. It is illustrated. In the second embodiment, the same members and portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0043] Here, EPS brushless motors are required to be highly flexible and compatible with a wide variety of vehicle body lineups. However, brushless motors are still more expensive than brushed motors, and how to manufacture motors with a wide variety of specifications, including methods for processing single parts, has become a major issue. For example, the motor energization timing needs to be changed as appropriate according to various specifications. Especially for EPS motors, the specifications of the body (left and right of the handle, etc.) will be diversified. In order to share parts as much as possible, various specifications are often supported by changing the energization timing.

Such a change in the energization timing can be arbitrarily made by design depending on the configuration of the stator side and the rotor side, and the following change method is known. First, as a method of changing the energization timing on the stator side, there is a method of changing the angular positional relationship in the circumferential direction between the resolver stator and the stator core. In this case, there are two ways to change the positional relationship: changing the angular position of the resolver stator and changing the angular position of the stator core. In the former case, the resolver stator is integrated with the connector that connects the sensor wires, so the structure of the resolver stator must be changed in order not to change the sensor connector pull-out position.

[0045] On the other hand, in the latter case, the stator core is integrated with the external connection terminal (power connector) via the terminal unit. Therefore, in order not to change the drawing position of the external connection terminal, the structure of the terminal unit is not changed. Need to change. In other words, when the energization timing is changed on the stator side, the resolver stator and terminal unit must be changed significantly.

Next, as a method of changing the energization timing on the rotor side, there is a method of changing the angular positional relationship in the circumferential direction between the rotor magnet and the resolver rotor. In this case, in the motor 1 of the first embodiment, the angular positional relationship between the magnet 24 and the resolver rotor 35 can be easily changed by changing the position of the resolver rotor connecting piece 57 formed in the magnet holder 51 in the circumferential direction. can do. Therefore, when the change on the stator side is compared with the change on the rotor side, the specification on the rotor side can be changed more easily.

However, in order to change the setting on the force rotor side, it is necessary to change the position of the resolver rotor connecting piece 57, and to change the setting, it is necessary to individually design the dedicated magnet holder 51. Therefore, for the magnet holder 51, a new mold must be produced each time according to the specifications. However, the mold of the magnet holder 51 is relatively large, and the shape of the part for holding and fixing the magnet 24 is complicated, so that the mold structure is also complicated. Therefore, the cost required to manufacture the mold increases, the magnet holder is not an inexpensive part, and a considerable increase in cost is unavoidable due to the change in the energization timing! there were.

[0048] Therefore, in the brushless motor 71 according to the second embodiment of the present invention, the magnet holder 72 is divided into two in the axial direction, and the magnet holder is shared, thereby realizing a reduction in mold cost. In other words, in the brushless motor 71, the magnet holder 72 is composed of two parts, that is, a magnet holding part 73 and a resolver rotor connecting part 74, and both are integrally joined by a holder joining part 75. FIG. 5 shows the configuration of the magnet holding portion 73, and FIG. 6 shows the configuration of the resolver rotor connecting portion 74. As shown in FIG. 5, the magnet holding portion 73 has a configuration in which the lower half of the magnet holder 51 of FIG. 2 is made independent, and a base portion 76 and a holder arm 77 are formed.

As with the magnet holder 51, the holder arm 77 extends from the base portion 76 in the axial direction. The holder arm 77 has a substantially T-shaped cross section. Between the adjacent holder arms 77, the magnet 24 is pressed into the axial force. As a result, the magnet 24 is held and fixed between the outer peripheral surface of the rotor core 23 and the holder arm 77. The base portion 76 is formed in a ring shape. The base portion 76 is formed with a shaft through hole 78 through which the rotor shaft 22 is passed. A fitting groove 79 is formed around the shaft through hole 78 along the axial direction. The fitting groove 79 is equally divided into three force points in the circumferential direction.

On the other hand, a resolver rotor connecting piece 57 is provided on the right end side of the resolver rotor connecting portion 74 in FIG. 6 (a). The resolver rotor connecting pieces 57 are projected from the end of the resolver rotor connecting portion 74 in the axial direction, and are formed in three equal portions in the circumferential direction. As described above, the resolver rotor connecting piece 57 includes a base piece portion 58 and a fitting claw 59 and is lightly press-fitted into the fitting groove 66 of the resolver rotor 35. Further, a fitting piece 81 used for connection to the magnet holding portion 73 is also provided on the left end side of the resolver rotor connecting portion 74 so as to project. The fitting pieces 81 are arranged in three equal positions in the circumferential direction corresponding to the fitting grooves 79 of the magnet holding portion 73. A holder joint 75 is formed by the fitting groove 79 and the fitting piece 81. The circumferential dimension of the fitting piece 81 is slightly larger than the circumferential dimension of the fitting groove 79. The resolver rotor connecting portion 74 is attached to the magnet holding portion 73 in such a manner that the fitting piece 81 is lightly press-fitted into the fitting groove 79.

[0051] In such a magnet holder 72, when the circumferential position of the fitting piece 81 is changed, the magnet The circumferential positional relationship between the net 24 and the resolver rotor connecting piece 57 changes. That is, it is possible to appropriately change the angular positional relationship between the magnet 24 and the resolver rotor 35 by setting the position of the fitting piece 81. In this case, in the magnet holder 51 as shown in FIG. 2, as described above, it is necessary to change the design of the entire magnet holder 51. Therefore, it is necessary to newly create a large and complicated mold. On the other hand, in the motor 71 of the second embodiment, in order to change the angular positional relationship between the magnet 24 and the resolver rotor 35, it is only necessary to change the design of the resolver rotor connecting portion 74. It can be shared as it is.

That is, in the motor 71, without changing the shape of the magnet holding portion 73, the energization timing can be changed only by adjusting the angle of the position of the resolver rotor connecting piece 57 in the resolver rotor connecting portion 74 in the circumferential direction. It can be performed. Therefore, it is possible to respond to a wide variety of specifications only by changing the resolver rotor connection part 74, and there is no need for a large and complicated new mold when changing specifications, and it is possible to flexibly respond to many vehicle body lineups with cheaper parts. The power S can be. In addition, the resolver rotor connecting portion 74 for newly producing a mold can be formed with a simple mold divided into upper and lower parts because of a simple shape without an undercut portion. Therefore, according to the motor of the present invention, it is possible to provide a product excellent in cost performance with reduced mold costs.

[0053] Furthermore, since the resolver rotor connecting portion 74 can be manufactured by cutting without producing a mold, it is possible to shorten the lead time for producing a prototype when considering a small production such as a prototype. It becomes possible. Note that there are specifications for brushless motors with different magnetic circuit lengths. However, if the magnet holder with a short magnetic circuit length can be used to hold the magnet of a long motor sufficiently, it can be shortened. It is sufficient to make only the magnet holder. Therefore, the part specifications can be reduced correspondingly, and the cost can be further reduced.

[0054] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, the above-described embodiment shows a configuration in which the resolver rotor connecting piece 57 and the fitting groove 66 form the resolver coupling portion 63, and the fitting groove 79 and the fitting piece 81 form the holder joint portion 75. The unevenness is arranged on either side of the force S, the joint 63, and the joint 75. It can be changed as appropriate. For example, in the resolver coupling portion 63, a pin may be planted on the resolver rotor 35 side, and a notch hole, a groove, or the like into which the pin can be fitted may be provided in the magnet honorada 51. Further, the concave-convex relationship at the holder joint 75 may be set in reverse.

[0055] Further, in the above-described embodiment, the configuration in which both the spacers on both sides of the resolver rotor are eliminated is shown. However, in FIG. 1 of the resolver rotor 35 in which the flange portion 64 is not provided, only the spacer on the right side is provided. It may be arranged. In addition, the magnet holders 51 and 71 may be configured to fix the magnet holders 51 and 71 to the rotor core 23 with the force S configured to be fixed to the rotor shaft 22.

On the other hand, in the above-described embodiment, the force S shown in the example in which the stator according to the present invention is used in a brushless motor used as an EPS drive source, the stator is not limited to the EPS brushless motor, It can be widely applied to brushless motors for other purposes. In addition to EPS and motors for various on-vehicle electric products, the present invention is widely applicable to general brushless motors. Further, in the above-described embodiment, the present invention can be applied to other types of EPS motors such as the force S shown for the brushless motor used in the rack assist type EPS and the column assist type.

Claims

The scope of the claims

[1] A stator comprising a stator core and a coil wound around the stator core;

A rotor that is rotatably arranged with respect to the stator and includes a rotor shaft, a rotor core fixed to the rotor shaft, and a magnet attached to an outer periphery of the rotor core;

A resolver comprising: a resolver rotor attached to the rotor shaft; and a resolver stator disposed outside the resolver rotor;

And a magnet holder provided with a magnet holding part that is attached to the rotor and holds and fixes the magnet on an outer periphery of the rotor core, and a resolver rotor connection part connected to the resolver rotor. Brushless motor.

[2] The brushless motor according to claim 1, wherein a resolver coupling portion that couples the resolver rotor connection portion and the resolver rotor is provided between the resolver rotor connection portion and the resolver rotor. Brushless motor.

[3] The brushless motor according to claim 2, wherein the resolver coupling portion includes a resolver rotor connection piece formed in the resolver rotor connection portion and extending in an axial direction, and a resolver rotor connection piece formed in the resolver port. And having a fitting portion to be fitted.

[4] The brushless motor according to claim 3, wherein the resolver rotor connecting piece has a predetermined angular positional relationship with respect to the magnet, and the fitting portion has a predetermined portion and a convex portion formed on an outer periphery of the resolver rotor. A brushless motor having an angular positional relationship of

5. The brushless motor according to claim 1, wherein the rotor shaft has a flange portion that contacts the resolver port and restricts movement of the resolver rotor in the axial direction.

6. The brushless motor according to claim 1, wherein the resolver rotor connecting portion and the magnet holding portion are separable.

[7] The brushless motor according to claim 6, wherein a holder joint portion for joining the resolver rotor connection portion and the magnet holding portion is provided between the resolver rotor connection portion and the magnet holding portion. Features a brushless motor. [8] The brushless motor according to claim 7, wherein the holder joint portion includes a fitting piece formed in the resolver port connecting portion and extending in an axial direction, and a fitting piece formed in the magnet holding. A brushless motor characterized by having a mating portion.