JP2002359946A - Motor for motor-operated power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a constitution, capable of fixing a core shaft precisely, when a retaining cylinder part has working error, in a case that the core shaft of an armature is rotatably retained via a bearing by a retaining cylinder part formed on a cylinder bottom surface part of a closed-end cylindrical yoke, in an electric motor for motor-operated power steering. SOLUTION: In the constitution, an outer ring 10a of a bearing 10 is forcibly inserted in the retaining cylinder part 2b, and the core shaft 5 is inserted in a bearing inner ring 10b. In another case, a precision formed sleeve 11 is interposed between a bearing outer ring 10a and the retaining cylinder part 2b, and thereby the constitution is obtained where a gap is not formed between the bearing outer ring 10a and the inner peripheral part of the retaining cylinder part 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of a motor for electric power steering mounted on a vehicle.

[0002]

2. Description of the Related Art Today, an electric power steering system is employed in many vehicles to facilitate steering operation. And in such an electric power steering system, an electric motor is adopted as a drive source,
Attempts have been made to mount the electric motor in a steering column. The electric motor for electric power steering has a problem that whirling occurs more easily than a general-purpose motor because it has a large current, a high torque, and a low rotation speed. Further, in such a case, the electric motor is disposed immediately before the driver, and particularly quietness is required. The demand for quietness has become even more severe in recent vehicles, due to the improvement in quietness inside the vehicle.

[0003]

However, in the conventional electric motor, a support cylinder is formed on the bottom of a cylindrical yoke having a bottom, and one end of a core shaft of an armature core is formed on the support cylinder. Although it was rotatably supported via a bearing, this support structure is such that a core shaft is press-fitted into an inner ring of the bearing, and an outer ring of the bearing is inserted (or lightly press-fitted) into a support cylinder. However, since the yoke is formed by drawing, there is a problem that the accuracy of the support cylinder is difficult to obtain. If there is a gap of about 10 μm (micrometer) between the bearing outer ring and the support cylinder, the deflection of the armature core is caused. There is a problem that a noise is generated by the rotation of the outer ring of the bearing hitting the support cylindrical portion, which is unpleasant noise, and there is a problem to be solved by the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems in view of the above circumstances, and a first invention is an electric power supply mounted on a vehicle. An armature comprising: a motor for steering, wherein the motor is rotatably supported at one end of a core shaft via a bearing in a yoke having a bottomed cylindrical shape and a support cylinder recessed in the bottom of the yoke via a bearing. In the configuration including the core, the outer ring of the bearing is press-fitted into the support cylindrical portion, and the core shaft is inserted into the inner ring of the bearing. By doing so, it is possible to prevent abnormal noise generated due to rotation of the core shaft and to provide a quiet electric motor. Further, a second invention is a motor for electric power steering mounted on a vehicle, wherein the motor is provided with a yoke having a bottomed cylindrical shape and a bearing in a support cylinder portion recessed in the bottom surface of the yoke. The armature core is rotatably supported at one end of the core shaft through a sleeve, the sleeve is incorporated into the support cylinder, and the outer ring of the bearing is press-fitted into the sleeve. is there. This makes it possible to prevent abnormal noise generated by the rotation of the core shaft due to the rotation, thereby providing a quiet and durable electric motor. In this case, the sleeve of the present invention can be characterized by being formed of a material having higher rigidity than the yoke. Further, in this case, the sleeve of the present invention can be characterized by being formed of a material having lower rigidity than the yoke. In this case, the sleeve of the present invention may be characterized in that an elastic member is fixed to the outer periphery.

[0005]

Next, a first embodiment of the present invention will be described with reference to the drawings. In the drawing,
1 is an electric motor for electric power steering,
The electric motor 1 includes a cylindrical yoke 2 having a bottom and a yoke 2.
, An armature core 4 rotatably provided inside the permanent magnet 3, a core shaft 5 of the armature core 4, a commutator 6 provided on the core shaft 5, and a sliding contact with the commutator 6. It is composed of various members such as a brush 7, an elastic machine 8 for urging the brush 7, an end case 9 for covering the opening of the yoke 2, and a torque limiter T disposed in a concave portion 9a formed in the end case 9. Are the same as before.

One end of the core shaft 5 is rotatably supported via a bearing 10 on a support cylinder 2b recessed in the cylinder bottom 2a of the yoke 2 and the other end is mounted on the end case 9 with the bearing 1
1, the present invention is applied to the support of one end of the core shaft 5 by a bearing 10. First, the bearing 10 has a steel ball 10c interposed between the outer ring 10a and the inner ring 10b, and is dimensioned such that the outer ring 10a is press-fitted into the inner circumferential surface of the support cylindrical portion 2b.
One end of the core shaft 5 is inserted into the inner ring 10 b of the press-fitted bearing 10.

In the structure described above, the bearing outer ring 10a is press-fitted into the supporting cylinder 2b, which is formed by drawing and is difficult to obtain dimensional accuracy, thereby forming the supporting cylinder 2b and the bearing outer ring 10a. There is no gap between them, and no abnormal noise is generated due to the armature core 4 whirling, and the durability can be improved.

On the other hand, the core shaft 5 inserted into the bearing inner ring 10b can be made to have high dimensional accuracy by being polished, and the clearance between the core shaft 5 and the bearing inner ring 10b can be made small without generating abnormal noise. In addition, if the electric motor is for electric power steering and has a large current, a high torque, and a low rotation speed, and the armature core 4 whirls, the core shaft 5 is
b, the tapping sound reaches the outside via a long path of reaching the yoke support tubular portion 2b via the inner ring 10b, grease, steel balls 10c, grease, and the outer ring 10a. Of the support cylinder 2 with the outer ring 10a
Unlike a device that directly hits “b”, it does not produce a direct tapping sound to the outside, so that the tapping noise can be reduced. In addition, a damper effect is generated in the grease and the steel ball 10c in this path, and the generation of abnormal noise can be further reduced, so that quietness can be improved.

The present invention is not limited to the above-mentioned embodiment, but can be made as in the second embodiment shown in FIGS. In this case, a sleeve (bearing sleeve) is provided between the bearing outer ring 10a and the support tubular portion 2b.
11 has been incorporated. In other words, it is difficult to improve the dimensional accuracy of the inner circumference of the support cylinder 2b because the yoke support cylinder 2b is formed by drawing. However, since the sleeve 11 is formed by molding, the inner circumference of the sleeve 11 is formed. The dimensional accuracy can be improved, and as a result, the inner diameter of the sleeve 11 does not vary,
The bearing outer ring 10a can be press-fitted and assembled with high accuracy.

Further, the sleeve 11 of the second embodiment is formed of a material having a higher rigidity than the yoke 2, for example, stainless steel or spring steel. It has higher rigidity than the material. In this case, the sleeve 11 is press-fitted into the support cylinder 2b. In this case, however, the processing accuracy of the yoke 2 is poor, and the dimensional accuracy of the inner periphery of the support cylinder 2b is reduced (the dimensional accuracy varies). In this case, the inner periphery of the sleeve 11 can be prevented from being deformed by press-fitting the outer periphery of the highly rigid sleeve 11 so as to deform the inner periphery of the support cylinder portion 2b. As a result, the dimensional accuracy of the inner circumference of the sleeve 11 is ensured, and the outer ring 1
0a can be press-fitted with high accuracy.
A gap is formed between the bearing and the bearing outer ring 10a, and an abnormal noise is generated, or the clearance between the bearing outer ring 10a and the bearing inner ring 10b becomes an improper interval, and the steel ball 10c generates an abnormal noise. In addition, it is possible to eliminate such troubles as to improve the durability and to improve the durability.

On the other hand, as the sleeve 11, a material having a lower rigidity than that of the yoke 2, for example, a material such as rubber, resin, aluminum or the like can be used, and such a sleeve 11 is inserted into the support cylinder 2b. May be configured. In this case, even if there is a dimensional error (variation) in the support cylinder portion 2b, this can be absorbed by deformation on the outer periphery of the sleeve 11, and
The dimensional accuracy of the inner diameter can be ensured. As a result, it is possible to minimize the influence on the bearing 10 side, such as securing a clearance between the bearing outer ring 10a and the bearing inner phosphorus 10b. Can improve the performance.

Further, as the sleeve 12, FIGS.
The third embodiment shown in FIG.
The sleeve 12 of the present embodiment has an elastic member 12 such as a rubber elastic material on an outer periphery of a sleeve main body 12a formed of a steel material.
b is integrally fixed. in this case,
The sleeve main body 12a has dimensional accuracy secured by molding, and the material may be any of a high rigidity material and a low rigidity material. Reference numeral 12a denotes a pipe-shaped body molded from aluminum, and a cylindrical elastic member 12b (rubber material) is integrally fixed to the outer periphery of the sleeve body 12a. The dimensional accuracy of the inner circumference of 12a can be ensured. In addition, in this case, since the elastic member 12b is provided on the outer periphery, the sleeve main body 12a press-fitted into the yoke support cylinder 2b is assembled.
When the bearing outer ring 10a is press-fitted into the inner periphery, the force of assembling the bearing 10 can be reduced by the elastic deformation of the elastic member 12b.
The axial (axial) force generated between the bearing 10 and the bearing inner ring 10b is reduced, and the bearing 10 can be protected. As a result, also in this case, it is possible to reduce inconveniences such as the occurrence of abnormal noise as described above, and to improve the durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a motor according to a first embodiment.

FIG. 2 is an enlarged sectional view of a main part of the first embodiment.

FIG. 3 is a cross-sectional view of a motor according to a second embodiment.

FIG. 4 is an enlarged sectional view of a main part of the second embodiment.

FIG. 5 is a sectional view of a motor according to a third embodiment.

FIG. 6 is an enlarged sectional view of a main part of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric motor 2 Yoke 2b Support cylinder part 5 Core shaft 10 Bearing 10a Outer ring 10b Inner ring 11 Sleeve

Claims (5)

[Claims] 1. A motor for electric power steering mounted on a vehicle, comprising: a motor having a bottom and a cylindrical yoke; An armature core having one end of the shaft rotatably supported, wherein the outer ring of the bearing is press-fitted into the support cylinder and the core shaft is inserted into the inner ring of the bearing. Motor. 2. A motor for electric power steering mounted on a vehicle, comprising: a motor having a bottomed cylindrical yoke; An armature core in which one end of a shaft is rotatably supported includes a sleeve incorporated in the support cylinder, and an outer ring of a bearing is press-fitted into the sleeve. motor. 3. The electric power steering motor according to claim 2, wherein the sleeve is formed of a material having higher rigidity than the yoke. 4. The electric power steering motor according to claim 2, wherein the sleeve is formed of a material having lower rigidity than the yoke. 5. The electric power steering motor according to claim 2, wherein an elastic member is fixed to an outer periphery of the sleeve.