JPH1198752A - Motor bearing structure - Google Patents

Abstract

(57) [Summary] In a bearing structure used for an electric motor, the rotation shaft is prevented from deteriorating due to deformation of a ball bearing race surface generated when a ball bearing is fixedly pressed into contact with a rotating shaft and a housing, and stable rotation is achieved. It is an object of the present invention to provide an inexpensive bearing structure with low shaft runout that can maintain accuracy. When a ball bearing is fixedly mounted on a rotating shaft or a housing by pressure contact, a pressure contact portion is approximately 1 / l of the entire length of the ball bearing.
2 or less, and the pressure contact portion is formed on the side opposite to the contact portion between the ball in the ball bearing and the race surface, so that the roundness of the rotating shaft and the housing is poor or the press-fitting allowance is reduced. Complete the deformation of the race surface of the ball bearing that occurs when it is large at a position that does not affect the runout of the rotating shaft,
An inexpensive bearing structure with less shaft runout can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor bearing structure.

[0002]

2. Description of the Related Art Conventionally, sliding bearings and ball bearings have been used as bearings for electric motors to support a rotating shaft, and ball bearings are generally used for those requiring high load and long life. When the shaft runout is required with high precision, it is necessary to prevent the runout due to the clearance or the like between the rotating shaft and the ball bearing engaging portion.

[0003] Conventional bearing structures that meet such demands are disclosed in Japanese Patent Application Laid-Open Nos.
As described in Japanese Patent Publication No. 317586, there is known a structure in which a ball bearing and a rotating shaft are fitted and fixed by press-fitting in order to eliminate the above-mentioned clearance.

[0004]

However, when such a structure is employed, when the rotary shaft and the ball bearing are press-fitted, if the roundness of the rotary shaft is poor or if the press-in allowance is large, the race surface of the ball bearing is deformed. Therefore, there is a problem that the deflection of the rotating shaft is deteriorated.

The present invention has been made in view of the above-mentioned problems, and the deformation of the race surface of the ball bearing, which occurs when the roundness of the rotating shaft is poor or the press-fitting allowance is large, does not affect the shaft runout of the rotating shaft. It is an object of the present invention to provide an inexpensive bearing structure that is stable and has little shaft runout.

[0006]

SUMMARY OF THE INVENTION In order to solve this problem, according to the present invention, a rotary shaft is mounted in pressure contact with an inner ring portion of a ball bearing, and the pressure contact portion is less than approximately 1/2 of the entire length of the ball bearing. The pressure contact portion is formed on the opposite side of the contact portion between the ball bearing inner ball and the inner race surface.

Thus, the deformation of the race surface of the ball bearing, which occurs when the roundness of the rotary shaft is poor or the press-in allowance is large, is completed at a position that does not affect the runout of the rotary shaft,
Stable rotational accuracy can be maintained, and an inexpensive bearing structure with less shaft runout can be realized.

[0008]

DETAILED DESCRIPTION OF THE INVENTION According to a first aspect of the present invention, in a bearing structure for supporting a rotor of an electric motor, a rotating shaft of the rotor is rotated by a plurality of bearings at least one of which is constituted by a ball bearing. While being held freely, the rotating shaft is attached by pressing against the inner ring portion of the ball bearing,
The pressure contact portion is formed within a range of approximately 1/2 or less of the entire length of the ball bearing, and the pressure contact portion is formed on a side opposite to a contact portion between the ball bearing inner ball and the inner race surface. By arranging the pressure contact part at a position separated from the ball contact part in the bearing, the deformation of the ball bearing race surface generated at the time of pressure contact between the rotating shaft and the ball bearing inner ring part is reduced to the ball contact position in the bearing. The operation is completed at a position where no influence is exerted, and has an effect of not affecting the shaft runout of the rotating shaft.

According to a second aspect of the present invention, in a bearing structure for supporting a rotor of an electric motor, a rotating shaft of the rotor is rotatably held by a plurality of bearings at least one of which is constituted by a ball bearing, The bearing is fixed to the housing by press-contacting an outer ring portion of the ball bearing, and the press-contact portion is formed within a range of approximately １ ／ or less of the entire length of the ball bearing,
The pressure contact portion is formed on a side opposite to a contact portion between the ball bearing inner ball and the outer ring race portion, and the pressure contact portion is arranged at a position separated from the bearing inner ball contact portion. By this, the deformation of the ball bearing race surface that occurs when the housing and the ball bearing outer ring part are pressed against each other is completed at a position that does not affect the ball contact position in the bearing, and has the effect of not affecting the shaft runout of the rotating shaft. Have.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 1 shows a bearing structure according to a first embodiment of the present invention. In FIG. 1, a rotating shaft 1 of a rotor (not shown) is rotatably supported by ball bearings 2 and 3. Reference numeral 4 denotes a housing in which ball bearings 2 and 3 are housed.
Reference numeral 5 denotes a spring which applies a preload to the ball bearings 2 and 3 so that the contact portion between the race surface 6 of the inner race and the ball 7 is point A and the contact portion between the race surface 8 of the outer race and the ball 7 in the ball bearing 2. Is point B. Similarly, the race surface 9 of the inner race of the ball bearing 3 and the ball 1
The preload is urged so that the contact portion of 0 is point C and the contact portion of the race 10 of the outer race with the ball 10 is point D. Reference numeral 14 denotes a rotor frame press-fitted and fixed to the rotating shaft.

On the other hand, the rotating shaft 1 has a large diameter portion 31 and a small diameter portion 32.
The large-diameter portion 31 is provided with a ball bearing 2
22 and 23 of the inner ring 13 of the ball bearing 3 are pressed and fixed, and the pressed portions 22 and 23 are substantially １ ／ or less of the entire length of the ball bearing, and are contact points A and B with the ball. Each of them is arranged at a position opposite to the point C.

With the above structure, the inner race surfaces 6, 9 corresponding to the press contact portions 22, 23 undergo stress deformation due to the rotation shaft press contact. Since the A and C portions are disposed at positions opposite to the press contact portions 22 and 23, the press contact is completed without being affected by the stress deformation, the rotation accuracy as a ball bearing can be maintained, and the rotation shaft can be maintained. It is possible to provide a structure that does not cause shaft runout.

(Embodiment 2) FIG. 2 shows a bearing structure according to Embodiment 2 of the present invention. In FIG. 2, a rotating shaft 1 of a rotor (not shown) is rotatably supported by ball bearings 2 and 3. Reference numeral 4 denotes a housing in which ball bearings 2 and 3 are housed.
Reference numeral 5 denotes a spring which applies a preload to the ball bearings 2 and 3 so that the contact portion between the race surface 6 of the inner race and the ball 7 is point A and the contact portion between the race surface 8 of the outer race and the ball 7 in the ball bearing 2. Is point B. Similarly, the race surface 9 of the inner race of the ball bearing 3 and the ball 1
The preload is urged so that the contact portion of 0 is point C and the contact portion of the race 10 of the outer race with the ball 10 is point D. Reference numeral 15 denotes an E-ring fitted and fixed to the rotating shaft, and supports a preload spring.

On the other hand, the housing 4 is formed in a shape having a large-diameter portion 41 and a small-diameter portion 42. The small-diameter portion 41 includes 62 portions of the outer ring 52 of the ball bearing 2 and 63 portions of the outer ring 53 of the ball bearing 3. The pressure contact portions 62 and 63 are arranged at positions substantially equal to or less than half of the entire length of the ball bearing and at positions opposite to the contact points B and D with the ball.

With the above construction, stress deformation due to housing pressure contact occurs on the outer race surfaces 8 and 11 corresponding to the press contact portions 62 and 63.
The contact portions B and D between the ball and the race surface are the aforementioned press contact portions 62,
By providing the structure in which the pressure contact is completed without being affected by the stress deformation by being disposed at the position opposite to the position 63, the rotation accuracy as the ball bearing can be maintained, and the shaft does not run out of the rotating shaft. Becomes possible.

In the above description, the two bearings are constituted by ball bearings, and both the bearings and the rotating shaft or the housing are press-fixed. However, only one ball bearing is press-fixed and fixed. However, the present invention can be similarly implemented by adopting the same pressure contact fixing structure as described above, or a structure in which one bearing is constituted by a sliding bearing.

[0018]

As described above, according to the present invention, by providing simple shapes such as a large-diameter portion and a small-diameter portion on the rotary shaft and the housing portion which engage with the ball bearing, the ball bearing, the rotary shaft, and the housing can be formed. With a pressure contact structure that minimizes clearance, deformation of the race surface due to pressure contact of the ball bearing, which occurs when the roundness of the rotating shaft and housing is poor or the press-fit allowance is large
An advantageous effect is obtained that an inexpensive bearing structure with little shaft run-out that can maintain stable rotation accuracy without affecting the shaft run-out of the rotating shaft can be obtained.

[Brief description of the drawings]

FIG. 1 is a bearing structure diagram showing an embodiment of the present invention.

FIG. 2 is a bearing structure diagram showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 Rotary shaft of rotor 2, 3 Ball bearing 4 Housing 5 Spring 6, 9 Inner race surface 7, 10 Ball 8, 11 Outer race surface 12, 13 Inner race 14 Rotor frame 15 E-ring 22, 23, 62 , 63 Pressure contact part 31 Large diameter part of rotating shaft 32 Small diameter part of rotating shaft 41 Large diameter part of housing 42 Small diameter part of housing 52, 53 Outer ring A, B, C, D Contact part between ball and race surface

Claims (2)

[Claims] In a bearing structure for supporting a rotor of an electric motor, a rotating shaft of the rotor is rotatably held by a plurality of bearings at least one of which is constituted by a ball bearing.
The rotating shaft is mounted in pressure contact with an inner ring portion of the ball bearing, and the pressure contact portion is formed within a range of approximately の or less of the entire length of the ball bearing, and the ball bearing inner ball and the inner ring race surface are A bearing structure for an electric motor, wherein the pressure contact portion is formed on a side opposite to the contact portion. 2. A bearing structure for supporting a rotor of an electric motor, wherein a rotating shaft of the rotor is rotatably held by a plurality of bearings at least one of which is constituted by a ball bearing.
The bearing is fixed to the housing by pressing the outer ring portion of the ball bearing in contact with the housing, and the pressure contact portion is one of the entire length of the ball bearing.
/ 2 or less, wherein the pressure contact portion is formed on the opposite side of the contact portion between the ball bearing inner ball and the outer race surface.