JP2002233112A - Motor-driven power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the ease of assembling by reducing the number of components for an electric motor in a motor-driven power steering device. SOLUTION: In the motor-driven power steering device 10, a motor casing 31 of the electric motor 30 is integrally formed of a yoke 52, a magnet holder 53, a brush holder 62, and a feed connector 63.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric power steering apparatus.

[0002]

2. Description of the Related Art An electric power steering apparatus is disclosed in
As described in JP-A-9-84300, an electric motor is fixed to a housing, an assist shaft of a steering device is supported on the housing, and the assist shaft is connected to a rotating shaft of the electric motor.

As described in Japanese Patent Application Laid-Open No. 8-205433, the electric motor includes a cylindrical yoke, a magnet holder having a magnet housing section formed on the inner periphery of the yoke, and a magnet housing section of the magnet holder. And a stator having a magnet to be mounted. Further, the electric motor
It has a rotor that is inserted inside the stator and fixed to the rotating shaft, a brush that is brought into contact with a commutator of the rotor, a brush holder that holds the brush, and a power supply connector that is connected to the brush.

[0004]

The prior art has the following problems. Since the yoke, the magnet holder, the brush holder, the power supply connector, and the like that constitute the electric motor are formed as separate parts, the number of parts is large, and the number of assembly steps is also large.

[0005] To connect the power supply connector to the brush,
External wiring is required, and there is difficulty in managing the power supply circuit.

[0006] Since the brush holder for holding the brush and the magnet holder for positioning the magnet of the stator are separated, a phase shift occurs in the arrangement of the brush with respect to the arrangement of the magnet of the stator, and the rotational characteristics of the motor are correct. There is a difference between the reverse direction and the reverse direction, and there is a possibility that the performance is reduced. In order to eliminate the difference between the rotation performance of the electric motor in the forward direction and the reverse direction, a performance test is performed after the electric motor is assembled, and based on the result, the brush holder is rotated to arrange the brushes. Needs to be readjusted, which impairs productivity.

Since the end plate of the electric motor is fixed by bolts in order to fix the electric motor to the housing, it is essential that the electric motor has an end plate and fixing bolts.
Large number of parts and heavy weight.

An object of the present invention is to reduce the number of parts of an electric motor in an electric power steering device and improve the assembling property.

An object of the present invention is to improve the productivity of assembling an electric motor and improve the rotation performance in an electric power steering apparatus.

An object of the present invention is to reduce the number of parts of an electric motor and reduce the weight of the electric power steering apparatus.

[0011]

According to a first aspect of the present invention, an electric motor is fixed to a housing, an assist shaft of a steering device is supported on the housing, and the assist shaft is connected to a rotating shaft of the electric motor. An electric motor, a stator including a cylindrical yoke, a magnet holder forming a magnet housing section on the inner periphery of the yoke, a magnet housed in the magnet housing section of the magnet holder, and inserted inside the stator. An electric power steering device including a rotor fixed and fixed to a rotating shaft, a brush contacting a commutator of the rotor, a brush holder for holding the brush, and a power supply connector connected to the brush. , A yoke, a magnet holder, a brush holder, and a power supply connector are integrally formed as a motor case. A.

According to a second aspect of the present invention, in the first aspect of the present invention, the motor case is formed by resin-molding the magnet holder, the brush holder and the power supply connector, and insert-molding a yoke into the resin molded body. It was made.

According to a third aspect of the present invention, when the motor case is coupled to the housing, a commutator is provided on an end surface of the rotor opposite to the housing, and the motor case is connected to the housing. A brush holder is formed on the inner periphery of the housing, and a power supply connector is formed on an end surface of the motor case on the side opposite to the housing.

According to a fourth aspect of the present invention, in addition to the first to third aspects, the motor case is further press-fitted into the housing.

According to a fifth aspect of the present invention, in addition to the first to third aspects, the motor case is further screwed to the housing.

[0016]

According to the first and second aspects of the present invention, the following effects are obtained. Since the yoke, the magnet holder, the brush holder, and the power supply connector, which constitute the electric motor, are integrally formed in the motor case, the number of parts can be reduced and the assembling property can be improved.

Since the power supply connector is formed integrally with the motor case, it is not necessary to draw out the wiring connecting the power supply connector to the brush, and the layout of the power supply circuit can be simplified and simplified. Sealability such as waterproofing from the routing part can be easily secured.

Since the magnet holder and the brush holder are integrally formed, the phase of the brush held by the brush holder does not shift with respect to the magnet of the stator positioned by the magnet holder, and the rotational performance of the motor in the normal rotation direction and the reverse rotation direction. There is no difference and there is no performance degradation. Accordingly, it is not necessary to adjust the phase of the brush arrangement at the assembly stage, and the productivity can be improved.

According to the third aspect of the present invention, the following operations are provided. Since the electric motor has the power supply connector formed on the end face of the motor case on the side opposite to the housing, the outer shape of the electric motor including the power supply connector can be made more compact than that in which the power supply connector is formed on the outer periphery of the motor case.

According to the fourth aspect of the invention, the following operations are provided. Since the motor case is press-fitted into the housing as a structure for fixing the electric motor to the housing, an end plate of the electric motor and fixing bolts for the end plate are not required, so that the number of parts can be reduced and the weight can be reduced.

According to the fifth aspect of the invention, the following effects are obtained. Since the motor case is screwed into the housing as a structure for fixing the electric motor to the housing, the electric motor does not require an end plate or a fixing bolt for the end plate, thereby reducing the number of parts and reducing the weight. .

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway front view of an electric power steering apparatus, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of FIG. FIG. 4 is a sectional view showing a modification of the electric power steering device.

As shown in FIGS. 1 and 2, the electric power steering apparatus 10 includes a gear housing 1 made of an aluminum alloy and fixed to a body frame or the like by a bracket (not shown).
1 (first to third gear housings 11A to 11C). A pinion shaft 14 is connected to a steering shaft 12 to which a steering wheel is coupled via a torsion bar 13. It is supported by the first gear housing 11A so as to be movable left and right. Steering shaft 12 and pinion shaft 14
Between them, a steering torque detecting device 17 is provided. still,
The steering shaft 12 and the pinion shaft 14 have bearings 12A, 1
It is supported by the gear housing 11 via 4A and 14B.

As shown in FIG. 2, the steering torque detecting device 17 includes two detecting coils 17A surrounding a cylindrical core 17C engaged with the steering shaft 12 and the pinion shaft 14,
17B is provided in the third gear housing 11C. The core 17C is provided with a vertical groove 17E that engages with the guide pin 17D of the pinion shaft 14 so as to be movable only in the axial direction, and has a spiral groove 17G that engages with the slider pin 17F of the steering shaft 12. As a result, the steering torque applied to the steering wheel is applied to the steering shaft 12, and when a relative displacement in the rotational direction occurs between the steering shaft 12 and the pinion shaft 14 due to the elastic torsional deformation of the torsion bar 13, the steering shaft 12 The displacement of the pinion shaft 14 in the rotation direction causes the core 17C to be displaced in the axial direction, and the displacement of the core 17C changes the inductance of the detection coils 17A and 17B due to magnetic changes around the detection coils 17A and 17B. . That is, when the core 17C moves toward the steering shaft 12, the inductance of the detection coil 17A closer to the core 17C increases, and the inductance of the detection coil 17B closer to the core 17C decreases. Can be detected.

The rack shaft 1 in the first gear housing 11A
As shown in FIG. 2, a rack guide 19 is built in a cylinder portion 18 provided at a portion opposed to the pinion 15 with one end of the bush 6 interposed therebetween.
9A) is repelled toward the rack shaft 16 by a spring 21 supported on the back surface by a cap 20 attached to the cylinder portion 18 to press the rack 16A of the rack shaft 16 against the pinion 15 and to connect one end of the rack shaft 16 to the pinion 15. It is slidably supported. The other end of the rack shaft 16 is supported by a bearing 22. In the middle part of the rack shaft 16, left and right tie rods 23A, 23 are connected by connecting bolts 22A, 22B.
B is connected.

As shown in FIG. 3, a motor case 31 of an electric motor 30 is fixed to the second gear housing 11B, and a torque limiter 8 is mounted on a rotating shaft 32 of the electric motor 30.
0 is connected to the assist shaft 33,
Are supported at both ends of the second gear housing 11B by bearings 34 and 35 such as ball bearings. The inner ring of the bearing 34 is held by a stopper ring 36A, and the outer ring is held by a lock nut 36B. A worm gear 37 is integrally provided at an intermediate portion of the assist shaft 33, and a worm wheel 38 meshing with the worm gear 37 is connected to the pinion shaft 14.
It is fixed to the middle part of. The torque generated by the electric motor 30 is applied to the rack shaft 16 as a steering assist force via the engagement between the worm gear 37 and the worm wheel 38 and the engagement between the pinion 15 and the rack 16A. To assist the steering force.

Here, the electric motor 30 is configured as follows. That is, the electric motor 30 includes a cylindrical yoke 52 formed of a magnetic material such as iron, and a magnet formed of an insulating resin material forming a magnet housing section 53 </ b> A at a plurality of circumferential positions on the inner periphery of the yoke 52. Holder 5
3 and the magnet storage section 53 of the magnet holder 53
A magnet 54 housed in A and positioned and held;
There is provided a stator 51 including a magnet cover 55 formed of an ultra-thin plate of a nonmagnetic material which is press-fitted inside a magnet 54 positioned and held by a magnet holder 53. One end of the magnet cover 55 is an enlarged diameter flange 5
5A and press-fitted into the inner periphery of the yoke 52.

The electric motor 30 has a rotor 56 inserted inside the stator 51 and fixed to the rotating shaft 32. The rotor 56 includes an amateur core 57 and a commutator 58 provided on the outer periphery of the rotating shaft 32.

The electric motor 30 has a brush 61 which is brought into contact with the commutator 58 of the rotor 56, and a brush holder 62 made of an insulating resin material for positioning and holding the brush 61. The electric motor 30
Is a brush 61 positioned and held by a brush holder 62.
And a power supply connector 63 integrally formed of an insulating resin material having the connection terminal 63A built therein.

When electric power is supplied from the brush 61 to the armature core 57 via the commutator 58 of the rotor 56, the magnetic force lines of the armature core 57 are applied to the stator 51.
By cutting off the magnetic field generated by the magnet 54, the rotor 56 rotates.

However, the electric motor 30 has the following characteristic configuration. (1) The electric motor 30 forms the motor case 31 by integrally molding the yoke 52, the magnet holder 53, the brush holder 62, and the power supply connector 63. The motor case 31 uses the magnet holder 53, the brush holder 62, and the power supply connector 63 as a resin molded body, and inserts the yoke 52 into the resin molded body.

(2) In the electric motor 30, a commutator 58 is provided on the end face of the rotor 56 on the side opposite to the housing 11B, and a brush holder 62 is provided on the side of the motor case 31 opposite the housing 11B. The brush holder 62 is used for the motor case 31.
Base portion 62 forming an end surface on the side opposite to housing 11B
A and the magnet holder 53 from the outer edge of the base portion 62A.
The brush holding portion 62C is formed at a plurality of circumferential positions on the inner circumference of the short cylindrical portion 62B, and the spring 64 and the brush 6 are attached to the brush holding portion 62C.
The brush 61 is pressed against the commutator 58 on the end face of the rotor 56 by the spring force of the spring 64 in a direction along the axial direction of the rotor 56. In the electric motor 30, a power supply connector 63 is formed on an end surface of the motor case 31 on the side opposite to the housing 11B, that is, on a base portion 62A of the brush holder 62.

(3) The motor case 31 of the electric motor 30 is pressed into the housing 11B and fixed. That is, the yoke 52 (the magnet holder 53, which constitutes the motor case 31)
The second spigot portion 72 externally provided on the brush holder 62) itself was spigot-coupled, and both were press-fitted at the spigot coupling portion to be tightly fixed. At this time, between the axially intermediate portion of the first spigot portion 71 and the axially intermediate portion of the second spigot portion 72, an annular groove provided in the second spigot portion 72 (or the first spigot portion 71) is mounted. O-ring 73
Is interposed.

(4) The rotary shaft 32 of the electric motor 30 and the assist shaft 33 are connected by a torque limiter 80 that slides at an impact torque exceeding a certain limit torque. The torque limiter 80 is configured by pressing a driving-side member that rotates integrally with the rotating shaft 32 and a driven-side member that rotates integrally with the assist shaft 33 by a pressing member such as a disc spring. And
Inside the torque limiter 80, for example, the fitting shaft (or fitting hole) at the tip of the rotating shaft 32 can be relatively rotated with the fitting hole (or fitting shaft) at the tip of the assist shaft 33. The rotating shaft 32 and the assist shaft 33 are made coaxial by, for example, spigot coupling, and as a result, the rotating shaft 32 is
Bearing 44 made of a ball bearing, etc.
, And is not supported at the end of the rotating shaft 32 on the assist shaft 33 side, thereby eliminating the need for a bearing. The bearing 44 can be assembled at the center of the base 62A of the brush holder 62 that forms the motor case 31.

Hereinafter, the operation of the electric power steering device 10 will be described. (1) When the steering torque detected by the steering torque detecting device 17 is lower than a predetermined value, no steering assist force is required, and the electric motor 30 is not driven.

(2) When the steering torque detected by the steering torque detector 17 exceeds a predetermined value, a steering assist force is required, and the electric motor 30 is driven. The torque generated by the electric motor 30 is transmitted from the rotor 56 to the worm gear 37, the worm wheel 38, the pinion 15, and the rack 16A via the rotating shaft 32, and serves as a steering assist force for the wheels linked to the rack shaft 16.

Therefore, according to the electric power steering apparatus 10 of the present embodiment, the following operations are provided.

Since the yoke 52, the magnet holder 53, the brush holder 62, and the power supply connector 63, which constitute the electric motor 30, are formed as an integrally formed motor case 31,
The number of parts can be reduced and the assemblability can be improved.

Since the power supply connector 63 is formed integrally with the motor case 31, it is not necessary to draw out the wiring connecting the power supply connector 63 to the brush 61, and the layout of the power supply circuit can be simplified and the sealing is not required.

Magnet holder 53 and brush holder 6
2 are integrally formed, so that the phase of the brush 61 held by the brush holder 62 does not deviate from the phase of the brush 54 held by the brush holder 62 with respect to the magnet 54 of the stator 51 positioned by the magnet holder 53, and the rotational performance of the motor 30 is different between the normal rotation direction and the reverse rotation direction. And no performance degradation. This eliminates the need to adjust the phase of the arrangement of the brushes 61 during the assembling stage, thereby improving productivity.

Since the electric motor 30 has the power supply connector 63 formed on the end surface of the motor case 31 on the side opposite to the housing, the electric motor including the power supply connector 63 is different from the motor having the power supply connector 63 formed on the outer periphery of the motor case 31. 30 can be made compact.

Since the motor case 31 is press-fitted into the housing to fix the electric motor 30 to the housing 11B, the end plate of the electric motor 30 and fixing bolts for the end plate are not required, and the number of parts is reduced. Reduce and
Can be reduced in weight.

Further, in the present embodiment, a structure is adopted in which the rotating shaft 32 and the assist shaft 33 of the electric motor 30 are coaxial by, for example, spigot-joining each other inside the torque limiter 80. Only the bearing 44 is supported, and the other end of the rotating shaft 32 is not supported. Thereby, the number of bearings used for the rotating shaft 32 can be reduced, and the weight can be further reduced.

The electric power steering apparatus 10 shown in FIG. 4 differs from the electric power steering apparatus 10 shown in FIGS. 1 to 3 in that the motor case 31 of the electric motor 30 is screwed and fixed to the housing 11B. That is, the side of the first spigot 71 of the housing 11B and the second spigot 72 of the yoke 52 constituting the motor case 31.
The screw portions 71A and 72A are provided on the sides of the side, and the two are spliced together and screwed together to be tightly fixed.

The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and changes in design and the like can be made without departing from the gist of the present invention. The present invention is also included in the present invention.

[0046]

As described above, according to the present invention, in an electric power steering apparatus, the number of parts of an electric motor can be reduced, and assemblability can be improved. Further, according to the present invention, in the electric power steering device, it is possible to improve the productivity of assembling the electric motor and improve the rotational performance. Further, according to the present invention, in the electric power steering device, the number of parts of the electric motor can be reduced and the weight can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing an electric power steering apparatus partially cut away.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a sectional view showing a modification of the electric power steering device.

[Explanation of symbols]

 Reference Signs List 10 electric power steering device 11B gear housing (housing) 30 electric motor 31 motor case 32 rotation shaft 33 assist shaft 51 stator 52 yoke 53 magnet holder 53A magnet storage section 54 magnet 56 rotor 57 amateur core 58 commutator 61 brush 62 brush holder 63 power supply connector 71, 72 spigot 71A, 72A screw 80 torque limiter

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (5)

[Claims] An electric motor is fixed to a housing, an assist shaft of a steering device is supported on the housing, and an assist shaft is coupled to a rotation shaft of the electric motor. The electric motor comprises: a cylindrical yoke; A stator including a magnet holder that forms a magnet housing section on the inner periphery of the yoke, and a magnet housed in the magnet housing section of the magnet holder; and a rotor that is inserted inside the stator and fixed to the rotating shaft. An electric power steering apparatus comprising: a brush that is brought into contact with a commutator of a rotor; a brush holder that holds the brush; and a power supply connector that is connected to the brush. An electric power steering device characterized by being a motor case integrally formed with a connector. 2. The motor case according to claim 1, wherein the magnet holder, the brush holder, and the power supply connector are formed of a resin molded body, and a yoke is insert-molded in the resin molded body.
The electric power steering device according to claim 1. 3. When connecting the motor case to the housing, a commutator is provided on an end face of the rotor opposite the housing, and a brush holder is formed on an inner periphery of the motor case opposite the housing. 2. A power supply connector is formed on an end surface on the side opposite to the housing.
Or the electric power steering device according to 2. 4. The electric power steering apparatus according to claim 1, wherein the motor case is press-fitted into the housing. 5. The electric power steering apparatus according to claim 1, wherein the motor case is screwed to the housing.