JPH0135549Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a bearing structure, and in particular to a bearing structure that rotatably supports the rotating shaft of a drive motor for a VTR, floppy disk drive, etc. be.

[Background of the idea]

BACKGROUND ART Conventionally, brushless motors have been widely used as drive motors for VTRs, floppy disk drives, and the like because they are compact and can provide high torque.

FIGS. 3 and 4 show an overview of this type of brushless motor that has been known in the past. Here, the third
The figure is a sectional view showing the overall structure of the brushless motor, and FIG. 4 is an enlarged sectional view showing details of the bearing portion of the brushless motor shown in FIG. 3.

The brushless motor is composed of a rotor section 1 and a stator section 2, as shown in FIG. In the rotor portion 1, a rotating shaft 4 is inserted and fixed to the center shaft portion of a rotor yoke 3 formed in a circular bowl shape. A rotor magnet 5 is fixedly formed in the rotor and magnetized in segments along the circumferential direction. Further, in the stator section 2, a bearing boss 7 is fixed to a stator yoke 6 formed of a soft magnetic material, and a bearing boss 7 is located at a position facing the rotor magnet 5 with the boss 7 as the center. A plurality of drive coils 8 are arranged in a circular manner. As shown in FIG. 4, in the center shaft portion of the boss 7, a bearing hole 10 has a bearing hole 10 formed approximately in the center thereof and has a bearing bearing 9 having a height approximately equal to the width of the outer ring of a rolling bearing (described later) and protruding inward. is opened, and a rolling bearing 11 such as a ball bearing is mounted below the bearing receptacle 9 in the bearing hole 10, and
A sliding bearing 12 made of, for example, oil-less metal is press-fitted into the upper part of the bearing receiver 9.

By supporting the rotating shaft 4 erected in the rotor section 1 on the inner surface of the inner ring of the rolling bearing 11 and the inner surface of the sliding bearing 12, the rotor section 1 can be freely rotated with respect to the stator 2. It can be configured as follows.

In the bearing structure of the brushless motor configured as described above, a bearing 9 is formed in the middle of the bearing hole 10 of the boss 7, and a rolling bearing 11 and a sliding bearing 12 are press-fitted from both the upper and lower sides of the bearing 9, respectively. In particular, since the movable portion of the rolling bearing 11 and the sliding bearing 12 are prevented from coming into direct contact with each other, there is no risk of seizure occurring between the rolling bearing 11 and the sliding bearing 12.

However, in general, machining a through hole with a stepped portion is much less productive than machining a straight through hole with a constant diameter, which not only causes high costs, but also causes a bearing holder 9.
Since it becomes difficult to completely align the axes of the upper and lower bearing holes through the above-mentioned screws, problems such as smooth rotation of the rotating shaft 4 may be hindered occur.

In order to eliminate this problem, as shown in FIG.
After machining, the bearing receiver 14 is inserted into the bearing hole 15.
A method has also been devised in which the material is press-fitted into a predetermined position.

However, although this method is advantageous in that the axes of the bearing holes can be formed in a straight line, on the other hand, the bearing receiver 14 must be manufactured separately, and in addition, the boss 7 and This method is disadvantageous in terms of cost because it requires a lot of man-hours to assemble the bearing receiver 14, and cannot be said to be a practical method.

[Purpose of invention]

The present invention was devised to eliminate the drawbacks of the prior art described above, and aims to provide a bearing structure for a motor, etc., which can be implemented at low cost and has no fear of seizure.

[Summary of the idea]

In order to achieve the above object, the present invention has a straight bearing hole in the center shaft of the boss provided in the fixed part, a rolling bearing in this bearing hole, and an inner ring of the rolling bearing in the end face of the inner circumference. The rolling bearing is characterized by having sliding bearings formed with escape parts to avoid contact with the rolling bearing in two stages, upper and lower, so that the rotating part of the rolling bearing and the sliding bearing do not come into contact with each other.

[Example of idea]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a sectional view of a boss portion showing a first embodiment of the present invention, in which 20 is a boss, 21 is a bearing hole formed in the boss 20, 22 is a sliding bearing made of oil-less metal, etc. , Figures 3 and 4
Components similar to those shown in the figures are designated by the same reference numerals.

A bearing hole 21 having a constant diameter from the upper surface to the lower surface of the boss 20 is formed in the central axis portion of the boss 20 . A relief portion 23 for avoiding the inner ring portion of the rolling bearing 11 is formed on the inner periphery of the sliding bearing 22 on the side that comes into contact with the rolling bearing 11.

The bearing structure of the brushless motor in the above example is as follows:
By forming the relief part 23 in the sliding bearing 22, the sliding bearing 22 is prevented from coming into direct contact with the inner ring portion of the rolling bearing 11, so seizing is prevented even without providing a bearing in the bearing hole as in the conventional case. No problems such as this will occur.

FIG. 2 is a sectional view of a boss portion showing a second embodiment of the present invention, in which relief portions are provided on the inner periphery of both the upper and lower parts of the sliding bearing 24 to avoid contact with the inner ring 11a of the rolling bearing 11. 25, 25a are formed.

The bearing structure of the brushless motor of the second embodiment has relief portions 25 on both upper and lower surfaces of the sliding bearing 24,
25a, there is no directionality when assembling the slide bearing 24, and it can be assembled in exactly the same way no matter which side faces the rolling bearing, which has the effect of further improving productivity. be.

[Effect of idea]

As explained above, in the bearing structure of the present invention, since the inner ring portion of the rolling bearing and the sliding bearing do not come into direct contact with each other, a bearing holder is provided in the bearing hole opened in the boss to separate the two, unlike conventional bearings. At least, there is no risk of burn-in. Therefore, since it is only necessary to open a straight hole as a bearing hole, machining of the boss becomes extremely easy, and manufacturing costs can be reduced accordingly.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing a second embodiment of the present invention, FIG. 3 is a cross-sectional view showing the overall configuration of a conventional brushless motor, and FIG. 4 and 5 are cross-sectional views showing the bearing structure of a conventional brushless motor. DESCRIPTION OF SYMBOLS 1...Rotor part, 2...Stator part, 3...Rotor yoke, 4...Rotating shaft, 5...Rotor magnet, 6...Stator yoke, 7...Boss, 8...
Drive coil, 9...bearing bearing, 10...bearing hole, 11...rolling bearing, 12...sliding bearing, 14...bearing bearing, 15...bearing hole, 2
0... Boss, 21... Bearing hole, 22, 24... Sliding bearing, 23, 25... Relief part.

Claims (1)

[Claims for Utility Model Registration] (1) A rolling bearing 11 and sliding bearings 22, 24 are installed in two stages, upper and lower, on the inner periphery of the boss 7 fixed to the fixed part 2, and these rolling bearings 11 and sliding bearings 22 , 24 rotatably supports the rotating shaft 4 of the rotating part 1,
A straight bearing hole 21 is formed in the central shaft portion of the boss 7, and the rolling bearing 11 is placed in the bearing hole 21, and relief portions 23, 25 are provided on the axial end surface to avoid contact with the inner ring of the rolling bearing 11.
A bearing structure characterized in that sliding bearings 22 and 24 each having a structure formed therein are housed in two stages, upper and lower. (2) The bearing structure according to claim 1, wherein the fixed part and the rotating part are a stator and a rotor of a motor.