JPH10201167A - Bearing structure of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the bearing structure of a motor which can reduce the bearing loss of a motor with a simple structure, and sharply improve the manhour in its processing at manufacture. SOLUTION: This is the bearing structure of a motor which has a rotor R supported rotatably through a sintered bearing 3 containing oil press-fitted in a bearing housing 2, and the same action just as two sintered bearings containing oil are arranged in the axial direction can be materialized with one sintered bearing 3 containing oil, by utilizing that the interference between the bearing housing 2 and the sintered bearing 3 containing oil changes during press fitting, by providing it with a hollow part 2 being staged in the inside periphery of this bearing housing 2 or the outside periphery of the sintered bearing 3 containing oil in advance.

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, and more particularly, to a motor bearing structure capable of reducing bearing loss and significantly improving the number of manufacturing steps.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made for a bearing structure of a brushed motor or a brushless motor, for example, one disclosed in Japanese Utility Model Laid-Open No. 6-5363. According to the above, bearings are arranged at two locations in the axial direction on the inner peripheral surface of the bearing holder fixed to the side plate with one end protruding from the case body, and the output shaft is rotatably supported. Met.

[0003]

However, in the above-mentioned configuration, in order to improve the vertical accuracy of the output shaft, bearings are generally arranged at two upper and lower positions in the axial direction, and the bearing span is long. It was a target. In this case, the shaft loss is inevitably increased by using only one bearing. Therefore, two bearings are required at the top and bottom to reduce the shaft loss. Then, since it is necessary to set the bearing separately from both ends of the bearing holder at the time of manufacture,
Processing man-hours increase significantly.

Therefore, the present invention solves the above-mentioned problems, and provides a motor bearing structure that can reduce the bearing loss of the motor with a simple structure and can greatly improve the number of machining steps during manufacturing. It is to try.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a bearing structure of a motor having a rotor rotatably supported via a sintered oil-impregnated bearing press-fitted into a bearing housing, and an inner peripheral surface of the bearing housing. Alternatively, by providing a hollow portion formed stepwise on the outer peripheral surface of the sintered oil-impregnated bearing, utilizing the fact that the interference between the bearing housing and the sintered oil-impregnated bearing changes at this hollow portion during press-fitting, One sintered oil-impregnated bearing can achieve the same effect as if two sintered oil-impregnated bearings were arranged at two locations in the axial direction.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor bearing structure according to the present invention is a motor bearing structure having a rotor rotatably supported via a sintered oil-impregnated bearing press-fitted into a bearing housing. The surface is provided with a stepped hollow portion. Further, in a bearing structure of a motor having a rotor rotatably supported via a sintered oil-impregnated bearing press-fitted into a bearing housing, a stepped hollow portion is provided on an outer peripheral surface of the sintered oil-impregnated bearing. It is what is done. When the first bearing surface of the sintered oil-impregnated bearing after the press-fitting is A and the second bearing surface is B, it is effective if A = B.

[0007]

FIG. 1 is a sectional view of a main part of a brushless motor according to an embodiment of the present invention. In FIG. 1, a bearing housing 2 is fixed to a stator base 1 by caulking or bonding, and an inner peripheral surface of the bearing housing 2 is provided with a hollow portion 2a which is stepped by cutting or the like. I have. A single sleeve-shaped sintered oil-impregnated bearing 3 is press-fitted into the inner peripheral surface of the bearing housing 2 in which the hollow portion 2a is formed, and a plurality of thin plates such as silicon steel plates are laminated on the outer peripheral surface of the bearing housing 2. Core 4 is fixed,
The core 4 has a plurality of coils 5 formed by windings.

A rotor R is rotatably supported via a sintered oil-impregnated bearing 3 disposed in a bearing housing 2, and a rotating yoke 7 is formed on a rotating shaft 6 in a cup shape.
A ring-shaped field magnet 8 is arranged on the inner peripheral surface of the rotor yoke 7 with a predetermined gap in the core 4. Reference numeral 9 denotes a receiving plate for holding one end of the rotating shaft 6.

Here, the bearing structure of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing a state before press-fitting the sintered oil-impregnated bearing into the bearing housing, and FIG. 3 is a view showing a state after press-fitting the sintered oil-impregnated bearing into the bearing housing. First, in FIG. 2, when the interference between the bearing housing 2 and the sintered oil-impregnated bearing 3 is 10 to 25 μm, it is known that the inner diameter of the bearing after press-fitting shrinks by about 3 to 7 μm.

Therefore, since the shrinkage of the sintered oil-impregnated bearing 3 varies depending on the interference, if the sintered oil-impregnated bearing 3 is pressed into the bearing housing 2 with a certain interference, a predetermined bearing inner diameter can be obtained. it can. In the case of the present invention, when the sintered oil-impregnated bearing 3 is press-fitted into the bearing housing 2, the bearing housing 2 is provided with a hollow portion 2a. The size is small or no compared to the part that is not hollowed out.

Therefore, in the press-fitted sintered oil-impregnated bearing 3, a portion 3a corresponding to the hollow portion 2a as shown in FIG.
A force acts in the direction indicated by the arrow between the other portion (ie, the bearing inner peripheral surfaces A and B that substantially support the rotating shaft 6), and the portion 3a corresponding to the hollow portion 2a has a bearing inner peripheral surface. The inner diameter of the bearing is formed to be several μm larger than A and B.
Also, if the relationship between the bearing inner peripheral surfaces A and B is A = B,
The rotating shaft 6 can be held uniformly in the axial direction.

Further, a hollow portion formed stepwise on the outer peripheral surface of the sintered oil-impregnated bearing 3 may be formed. In this case, the inner peripheral surface of the bearing housing 2 may be straight, not stepped. Even in this case, the inner peripheral surface of the sintered oil-impregnated bearing 3 is substantially the same as the above. 6 will have a first inner diameter and a second inner diameter larger than the first inner diameter.

The present invention is not limited to the above embodiment, but can be implemented with various modifications without departing from the gist of the present invention. For example, in the above-described embodiment, the brushless motor has been described in detail, but the same effect can be obtained with a motor with a brush. Also, the size of the hollow portion is not limited to the illustration and can be appropriately changed.

[0014]

As described above, according to the present invention, by providing a stepped hollow portion on the inner peripheral surface of the bearing housing or the outer peripheral surface of the sintered oil-impregnated bearing, the sintered oil-impregnated bearing is provided. Because a single sleeve shape can be used,
In terms of parts cost and processing cost, it is more advantageous than using two pieces, and it is not necessary to use expensive hollow metal.

Further, since the press-fitted sintered oil-impregnated bearing is substantially constituted by a first inner diameter for supporting the rotating shaft and a second inner diameter larger than the first inner diameter. Bearing loss can be greatly reduced as compared with a simple sleeve shape. Moreover, since the press-fitted sintered oil-impregnated bearing is hooked on the hollow portion of the bearing housing, the pull-out strength can be improved.

Further, since the sleeve is shaped like a sleeve as compared with the conventional one in which two pieces are arranged in the axial direction, a large oil content can be secured, and the reliability condition can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a brushless motor according to an embodiment of the present invention.

FIG. 2 is a view showing a state before press-fitting a sintered oil-impregnated bearing into a bearing housing.

FIG. 3 is a view showing a state after press-fitting a sintered oil-impregnated bearing into a bearing housing.

[Explanation of symbols]

 2 bearing housing 2a hollow part 3 sintered oil-impregnated bearing 6 rotary shaft R rotor

Claims (3)

[Claims] 1. A bearing structure of a motor having a rotor rotatably supported via a sintered oil-impregnated bearing press-fitted into a bearing housing, wherein a stepped hollow portion is formed on an inner peripheral surface of the bearing housing. A bearing structure for a motor, comprising: 2. A bearing structure for a motor having a rotor rotatably supported via a sintered oil-impregnated bearing press-fitted into a bearing housing, wherein the sintered oil-impregnated bearing has a stepped hollow on an outer peripheral surface thereof. A bearing structure for a motor, characterized in that the bearing structure is provided. 3. The bearing for a motor according to claim 1, wherein when the first bearing surface of the sintered oil-impregnated bearing after the press-fitting is A and the second bearing surface is B, A = B. Construction.