JPH06165433A - Motor - Google Patents

Abstract

PURPOSE:To provide a motor which can achieve the downsizing in axial direction and besides can support its own rotor stably. CONSTITUTION:A radial bearing 21 consisting of a roller bearing is provided at the center between a stator 11 and a rotor 17, and a thrust bearing 25 consisting of dynamic-pressure pneumatic bearing is provided around it, and the rotor 17 is provided rotatably by these radial bearing 21 and thrust bearing 25 to the stator 11. According to this, since the bearings are provided at the two places of the center and the periphery, the axial dimension can be made small as compared with the case where two pieces of bearings stand side by side. Moreover, it turns out that the rotor 17 is supported at the two places of the center and the periphery, the rotor 17 can be supported stably as compared with the case that it is supported only at the center.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 7 shows a conventional structure of a small motor. In FIG. 7, the stator 1 has a tubular portion 2a at the center of the housing 2 and a plurality of armature coils 5 on the outside of the tubular portion 2a with a stator yoke 3 and a printed wiring board 4 interposed therebetween.

The rotor 6 has a rotary shaft 8 in the center of a rotor yoke 7, and a field permanent magnet 9 axially opposed to the armature coil 5 on the outer side of the rotary shaft 8. Two radial bearings 8 each of which is a rolling bearing and is disposed above and below the cylindrical portion 2a.
It is rotatably supported by a and 10b.

[0004]

However, in the above-mentioned conventional structure, the two radial bearings 10a, 1 are provided.
0b are arranged side by side in the axial direction, the axial dimension of the motor as a whole is determined by the two radial bearings 10a and 10b.
However, it was difficult to reduce the size in the axial direction.

Two radial bearings 10a and 10b are also provided.
If the dimension between them, that is, the dimension between bearings is small, there is a problem that the support of the rotor 6 is likely to be unstable and so-called shaft run-out is likely to occur.

Therefore, an object of the present invention is to provide a motor which can be downsized in the axial direction and can stably support a rotor.

[0007]

In order to achieve the above-mentioned object, the present invention is capable of rotating a rotor having a stator having an armature coil and a field permanent magnet facing the armature coil. The radial bearing is provided on one of the central portion and the outer peripheral portion between the stator and the rotor, and the thrust bearing is provided on the other.

In this case, a radial bearing consisting of a rolling bearing is provided in the central portion between the stator and the rotor, a thrust bearing consisting of a dynamic pressure bearing is provided in the outer peripheral portion, and a central portion between the stator and the rotor is provided. A thrust bearing consisting of a dynamic pressure bearing and a radial bearing consisting of a rolling bearing in the outer peripheral part, or a radial bearing consisting of a rolling bearing in the central part between the stator and the rotor, and a rolling bearing in the outer peripheral part. A thrust bearing consisting of can be provided.

[0009]

According to the above-mentioned means, the bearings are provided at the two locations of the central portion and the outer peripheral portion between the stator and the rotor, so that compared with the case where the two bearings are arranged in the axial direction,
It is possible to reduce the axial dimension.

Further, since the rotor is supported through bearings at each of two locations, the central portion and the outer peripheral portion, the rotor can be supported more stably than when it is supported only at the central portion. You can

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. Housing 12 of the stator 11
In addition, a fixed shaft 13 is erected at the center thereof, and a plurality of armature coils 16 are annularly arranged on the outer upper surface of the fixed shaft 13 via a stator yoke 14 and a printed wiring board 15. ing.

On the other hand, the rotor yoke 18 of the rotor 17 is provided with a cylindrical portion 19 whose lower surface side is open at the center, and the armature coil 16 and the axial direction (upper and lower) are provided on the lower surface outside the cylindrical portion 19. A ring-shaped permanent magnet 20 for field magnet facing each other is mounted.

Between the outer peripheral surface of the fixed shaft 13 of the stator 11 and the inner peripheral surface of the cylindrical portion 19 of the rotor 17, there is provided a radial bearing 21 consisting of a rolling bearing having a large number of balls 21a. . The outer ring 21b of the radial bearing 21 is provided on the inner circumferential surface of the tubular portion 19 by gap fitting or adhesion, and between the inner ring 21c and the housing 12, a ring-shaped spacer 2 that applies a preload to the inner ring 21c.
It is assembled with 2 intervening.

Further, on the upper surface of the outer peripheral portion of the housing 12, as shown in FIG. 2, a groove 2 having a plurality of grooves is formed.
3 is provided in an annular shape so as to be concentric with the radial bearing 21, and a flat surface 24 facing the groove 23 is provided on the lower surface of the outer peripheral portion of the rotor yoke 18, and the dynamic pressure is formed by the groove 23 and the flat surface 24. A thrust bearing 25, which is an air bearing, is configured.

In this case, therefore, the rotor 17 is rotatably supported by the stator 11 via the radial bearing 21 in the central portion and the thrust bearing 25 in the outer peripheral portion.

According to the first embodiment described above, the stator 1
Since the radial bearing 21 is provided in the central portion between the rotor 1 and the rotor 17 and the thrust bearing 25 is provided in the outer peripheral portion, compared with the case where the two radial bearings 10a and 10b are provided side by side in the axial direction, It is possible to reduce the axial dimension of the motor.

Further, since the rotor 17 is supported by the radial bearing 21 at the central portion and the thrust bearing 25 at the outer peripheral portion, the rotor 17 is supported as compared with the case where it is supported only at the central portion. It can be stably supported, and the occurrence of shaft runout can be prevented as much as possible.

In the first embodiment described above, the groove 23 is provided on the housing 12 side of the stator 11, but the groove 23 may be provided on the rotor yoke 18 side.

FIG. 3 shows a modification of the first embodiment, which is different from the first embodiment in the following points. That is,
On the upper surface of the housing 12 in the stator 11,
Two annular concave portions 26, 26 are provided so as to be located inside and outside the groove 23, and two annular convex portions 27, which enter the concave portions 26, 26, are formed on the lower surface of the rotor yoke 18 of the rotor 17. 27 is provided, and the so-called labyrinth structure 28 is formed by the concave portions 26 and the convex portions 27.
Make up.

By injecting a lubricating fluid into the groove 23, a thrust bearing 29 composed of a hydrodynamic bearing can be constructed instead of the hydrodynamic air bearing of the first embodiment. At this time, the labyrinth structure 28 has the groove 23.
It exerts the function of preventing the fluid injected into the part from scattering.

On the other hand, FIGS. 4 and 5 show a second embodiment of the present invention, which will be described below. A circular convex portion 33 is provided at the center of the housing 32 of the stator 31, and a plurality of armature coils 36 are annularly formed on the upper surface outside the convex portion 33 via a stator yoke 34 and a printed wiring board 35. And a cylindrical portion 37 is integrally provided on the outside thereof.

On the other hand, the rotor yoke 39 of the rotor 38 has a convex portion 4 facing downward in the central portion corresponding to the convex portion 33.
0 is provided, and an annular permanent magnet 41 for field magnet axially opposed to the armature coil 36 is provided outside the convex portion 40.
Is attached, and the tubular portion 42 is integrally provided on the outside thereof.

Then, on the upper surface of the convex portion 33 of the stator 31, as shown in FIG.
Is provided in an annular shape, and the flat surface 44 of the lower surface of the convex portion 40 facing the groove 43 and the groove 43 constitute a thrust bearing 45 which is a dynamic pressure air bearing.

Further, between the inner peripheral surface of the cylindrical portion 37 of the housing 32 and the outer peripheral surface of the cylindrical portion 42 of the rotor 38, there is provided a radial bearing 46 which is a rolling bearing having a large number of balls 46a. .

In this case, therefore, the rotor 38 is rotatably supported by the stator 31 via the thrust bearing 45 in the central portion and the radial bearing 46 in the outer peripheral portion.

Also in such a second embodiment, the same operational effects as those of the above-mentioned first embodiment can be obtained.

FIG. 6 shows a third embodiment of the present invention, which is different from the above-described first embodiment in the following points. That is, in the third embodiment, instead of the thrust bearing 25 composed of the dynamic pressure air bearing in the first embodiment,
Between the upper surface of the outer peripheral portion of the housing 12 of the stator 11 and the lower surface of the outer peripheral portion of the rotor yoke 18 of the rotor 17, a thrust bearing 47 formed of a rolling bearing having a large number of balls 47a is provided.

In this case, therefore, the rotor 17 is rotatably supported by the stator 11 via the radial bearing 21 in the central portion and the thrust bearing 47 in the outer peripheral portion.

Also in such a third embodiment, it is possible to obtain the same effect as that of the first embodiment.

In each of the above-mentioned embodiments, the axial gap type motor in which the armature coils 16 and 36 and the field permanent magnets 20 and 41 are opposed to each other with a gap in the axial direction is shown as an example. Can also be applied to a radial gap type motor in which an armature coil and a field permanent magnet face each other with a gap in the radial direction.

[0031]

According to the motor of the first aspect, the bearings are provided at two locations, the central portion and the outer peripheral portion, between the stator and the rotor, so that the two bearings are arranged in the axial direction. The size in the axial direction can be made smaller than that in the case of arranging them side by side, and eventually the size can be made smaller in the axial direction.

Further, since the rotor is supported through bearings at each of two locations, the central portion and the outer peripheral portion, the rotor can be supported more stably than when it is supported only at the central portion. Therefore, the occurrence of shaft runout can be prevented as much as possible.

Also, in the motors described in claims 2, 3 and 4, the same effect as in claim 1 can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a first embodiment of the present invention.

FIG. 2 is a plan view of a housing portion of the stator.

FIG. 3 is an enlarged vertical sectional front view of a main part showing a modified example of the first embodiment.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG.

FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 1 showing a conventional configuration.

[Explanation of symbols]

11, 31 are stators, 16 and 36 are armature coils, 1
7, 38 are rotors, 20, 41 are field permanent magnets, 2
1, 46 are radial bearings, and 25, 29, 45, 47 are thrust bearings.

Claims (4)

[Claims] 1. A stator provided with an armature coil rotatably provided with a rotor provided with a field permanent magnet facing the armature coil, wherein a central portion and an outer periphery between the stator and the rotor. A motor characterized in that a radial bearing is provided on one of the parts and a thrust bearing is provided on the other. 2. A stator provided with an armature coil, wherein a rotor provided with a field permanent magnet facing the armature coil is rotatably provided, and a rotor is provided at a central portion between the stator and the rotor. A motor having a radial bearing formed of a bearing and a thrust bearing formed of a dynamic pressure bearing on the outer peripheral portion. 3. A stator provided with an armature coil rotatably provided with a rotor provided with a field permanent magnet facing the armature coil, wherein the rotor is provided at a central portion between the stator and the rotor. A motor comprising a thrust bearing formed of a pressure bearing and a radial bearing formed of a rolling bearing on the outer peripheral portion. 4. A stator provided with an armature coil rotatably provided with a rotor provided with a field permanent magnet facing the armature coil, wherein a rotor is provided at a central portion between the stator and the rotor. A motor comprising a radial bearing formed of a bearing and a thrust bearing formed of a rolling bearing on the outer peripheral portion.