JPH05252713A - Brushless motor - Google Patents

Abstract

PURPOSE:To provide a brushless motor used for the spindle motor of a floppy disc which materializes thinning. CONSTITUTION:This is a brushless motor comprising a rotor 11 equipped with a rotor yoke 15 for supporting a rotor magnet 14 to a shaft, a stator 21 equipped with a bearing housing 24 for supporting a stator yoke wherein an armature coil 22 is arranged, and two pieces of bearings 31 and 32 for supporting the rotor rotatably to the stator, and the two bearings are arranged in a circumferential direction on approximately the same level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to a brushless motor having a bearing mechanism.

[0002]

2. Description of the Related Art FIGS. 5, 6 and 7 are cross-sectional views of brushless motors used in conventional floppy disk drive (FDD) spindle motors. Figure 5
The first conventional brushless motor is shown in FIG. In FIG. 5, the first conventional brushless motor comprises a rotor 51 and a stator 61. The rotor 51 has a shaft 52, the shaft 52 arranged in the center, a hub 53 for clamping a disc, a rotor magnet 54, and the rotor magnet 54 attached thereto, and the rotor 51 is connected to the hub 53. It is composed of a rotor yoke 55 for forming a magnetic circuit.

The stator 61 is arranged face-to-face with the rotor magnet 54, an armature coil 62 for applying an electromagnetic force to the rotor magnet 54, a stator yoke 63 in which the armature coil 62 is arranged, and the stator. And a bearing housing 64 that supports the yoke 63. Between the outer circumference of the shaft 52 and the inner circumference of the bearing housing 64, ball bearings 65 and 66 arranged axially with respect to each other are mounted, and the rotor 51
Are rotatably supported by the stator 61.

FIG. 6 shows a second conventional brushless motor. In FIG. 6, the second conventional brushless motor has one ball bearing in order to realize a thin structure.
Instead of 66, a thin slide bearing 67 is used. The reason why the slide bearing 67 is used is that the ball bearing is structurally limited in its thinness.

FIG. 7 shows a third conventional brushless motor having a structure for further reducing the thickness of the second conventional brushless motor shown in FIG. In FIG. 7, in order to make the brushless motor of the third conventional example thinner,
The ball bearing 65 is also changed to the slide bearing 68, and the slide bearing
67 and a slide bearing 68 are axially arranged between the outer circumference of the shaft 52 and the inner circumference of the bearing housing 64, and a thrust bearing 69 is provided to fix the rotor 51 in the axial direction.

When only the slide bearings 67 and 68 are used as in the brushless motor of the third conventional example, the thrust bearing is used.
69 must be used, and the advantage of thinning the motor is the ball bearing as in the second conventional example shown in FIG.
The one with 65 and plain bearing 67 is larger. Further, when two slide bearings 67 and 68 are used, there is a disadvantage that the loss torque is large and the current consumption of the motor is large.

In the FDD system, which is required to be thin, the point is to make the spindle motor thin, and for that purpose, the most important point is to make the bearing mechanism section thin.

[0008]

As described above, the conventional brushless motor having a ball bearing or slide bearing axially arranged in the bearing mechanism has a limit in thinning, and further thinning is desired. Had the drawback of being difficult. The present invention has been made in order to eliminate such a conventional defect, and realizes a thin structure.
It is an object to provide a brushless motor used for a DD spindle motor.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a rotor having a rotor yoke for supporting a rotor magnet on a shaft, a stator having a bearing housing for supporting a stator yoke having an armature coil, and a rotor. Is a brushless motor that is rotatably supported with respect to the stator, and is characterized in that the two bearings are arranged at substantially the same height in the circumferential direction.

[0010]

Since the two bearings are not arranged axially with respect to each other but are arranged at substantially the same height in the circumferential direction, the bearing mechanism portion which has conventionally required the thickness of at least two bearings is a bearing. Just need a thickness that can store one,
It is possible to make the motor thinner, and it is possible to make the motor as a whole thinner.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. First, FIG. 1 is a sectional view of a brushless motor according to a first embodiment of the present invention. In FIG. 1, the brushless motor of the first embodiment of the present invention comprises a rotor 11 and a stator 21. The rotor 11 includes a shaft 12 and the shaft 12
Hub 13 where is fixed and disc is clamped
And a rotor magnet 14 magnetized in a plane with multiple poles, the rotor magnet 14 is attached, the inner circumference is connected to the hub 13, and the outer circumference is an annular outer peripheral projection 15a.
Is formed of a rotor yoke 15.

The stator 21 is disposed so as to face the rotor magnet 14 and has an armature coil 22 for applying an electromagnetic force to the rotor magnet 14, and a wiring board (not shown) to which the armature coil 22 is attached. It is composed of a stator yoke 23 that supports the wiring board and is provided with an annular stator outer peripheral projection 23a, and a bearing housing 24 that supports the stator yoke 23.

The brushless motor of the present invention is characterized in that the inner circumference of the slide bearing 31 is rotatably arranged with respect to the outer circumference of the shaft 12, and the outer circumference thereof is fixedly arranged to the inner circumference of the bearing housing 24. A ball bearing 32 is arranged at substantially the same height as the slide bearing 31, the inner ring of which is fixed to the outer circumference of the stator outer peripheral projection 23a of the stator yoke 23, and the outer ring of which is the outer peripheral projection 15a of the rotor yoke 15.
The point is that it is fixedly arranged on the inner circumference of the.

If the stator yoke 23 is made of a magnetic material, an attractive force is generated between the rotor magnet 14 and the stator yoke 23, and the rotor 11 is attracted to the stator 21, so that the ball bearing 32 is preloaded in the axial direction. be able to. Here, match the armature coil to the phase of the rotor magnet 14.
When electricity is applied to 22, the slide bearing 31 suppresses radial runout, and the axial runout is suppressed by the ball bearing 32 preloaded by the attraction force between the rotor 11 and the stator 21,
It rotates smoothly around axis 12.

As described above, since the two bearings are not arranged in the axial direction of each other but are arranged in the circumferential direction at substantially the same height, conventionally, at least the thickness of two bearings is required. However, the bearing mechanism portion can be thinned only by requiring a thickness that can accommodate one bearing, and the motor as a whole can be thinned.

FIG. 2 is a sectional view of the brushless motor according to the second embodiment of the present invention. The feature of the brushless motor of the second embodiment is that the rotor magnet 14 is mounted on the rotor yoke 15.
An annular rotor inner peripheral projection 16 is provided on the inner peripheral side of the sliding bearing.
The inner circumference of 31 is rotatably arranged with the outer circumference of the shaft 12, and the outer circumference thereof is fixedly arranged with the inner circumference of the bearing housing 24, and at the same height as the slide bearing 31, the ball bearing 32 is provided. Is located and its inner ring is the bearing housing 24
The outer ring is fixed to the outer circumference of the rotor, and the outer ring is fixed to the inner circumference of the rotor inner circumferential projection 16 disposed on the stator yoke 23. Similar to the first embodiment,
Since the bearings 31 and 32 are arranged at substantially the same height in the circumferential direction, it is possible to reduce the thickness.

3 and 4 show brushless motors according to the third and fourth embodiments of the present invention. The brushless motors of the first and second embodiments described with reference to FIGS. 1 and 2 are motors in which the rotor magnet 14 and the armature coil 22 face each other, but the third and fourth embodiments have stators. The yoke 23 is made of an iron core, and the iron core is made of a stator yoke 23 around which the rotor magnet 14 and the armature coil 22 are wound.

In the brushless motor of the third embodiment shown in FIG. 3, the rotor 11 has a shaft 12, a shaft 13 to which the shaft 12 is fixed, a disk 13 to be clamped, and an annular multipole magnetized. The cylindrical rotor magnet 14 and the innermost circumference are connected to the hub 13, and an annular inner rotor projection 16 for supporting the outer circumference of the rotor magnet 14 is provided outside the innermost circumference. Ring-shaped outer peripheral projection 15
and a rotor yoke 15 provided with a.

The stator 21 is arranged so as to face the rotor magnet 14 in the circumferential direction, and has a stator yoke 23 made of an iron core around which an armature coil 22 is wound, and a bearing housing 24 supporting the stator yoke 23. A stator base plate 25 having an inner periphery fixed to the bearing housing 24 and having an annular base plate outer peripheral protrusion 25a on the outer periphery is provided. The feature of the brushless motor of the third embodiment is that it is a plain bearing.
The inner circumference of 31 is rotatably arranged with the outer circumference of the shaft 12, and the outer circumference thereof is fixedly arranged with the inner circumference of the bearing housing 24, and at the same height as the slide bearing 31, the ball bearing 32 is provided. The inner ring is fixed to the outer circumference of the substrate outer peripheral projection 25a of the stator substrate 25, and the outer ring is fixed to the inner circumference of the rotor outer peripheral projection 15a arranged on the rotor yoke 15. Similar to the first and second embodiments, since the bearings 31 and 32 are arranged at substantially the same height in the circumferential direction, it is possible to reduce the thickness.

In the brushless motor of the fourth embodiment shown in FIG. 4, the rotor 11 has a cylindrical rotor magnet 14 which is magnetized in multiple rings in an annular shape, and an annular shape which supports the rotor magnet 14 on the inner circumference. The rotor yoke 15 has a rotor outer peripheral projection 15a. An annular rotor inner peripheral projection 16 is provided on the rotor yoke 15 on the inner peripheral side of the rotor magnet 14.

The stator 21 includes a stator yoke 23, which is an iron core around which an armature coil 22 is circumferentially opposed to the rotor magnet 14, and an intermediate projection of the stator yoke 23. 26, a stator substrate 25 to which the stator intermediate protrusion 26 is fixed, and a bearing housing 24 to which the stator substrate 25 is attached. The stator yoke 23 made of an iron core is attached to the bearing housing 24 via the intermediate stator protrusion 26 and the stator substrate 25.

The feature of the brushless motor of the fourth embodiment is that the inner circumference of the slide bearing 31 is rotatably arranged with the outer circumference of the shaft 12, and the outer circumference thereof is fixed to the inner circumference of the bearing housing 24. At the same time, the ball bearing 32 is arranged at substantially the same height as the slide bearing 31, the inner ring of which is fixed to the outer periphery of the bearing housing 24, and the outer ring of which is the inner portion of the rotor inner peripheral projection 16 disposed on the rotor yoke 15. The point is that they are fixedly attached to the circumference. Similar to the first, second and third embodiments, the bearings 31 and 32 are arranged at substantially the same height in the circumferential direction, so that it is possible to reduce the thickness.

In the above description, of the two bearings, the bearing arranged on the inner circumference is a slide bearing and the bearing arranged on the outer circumference is a ball bearing. Good.

[0024]

As described above, in the brushless motor of the present invention, the two bearings are not arranged axially to each other but are arranged at substantially the same height in the circumferential direction. The bearing mechanism, which had to have the thickness of one piece, only needs to be thick enough to accommodate one bearing, so it can be made thinner, and the motor as a whole can be made much thinner.

Further, even if the sliding bearing which has been conventionally used for thinning is not used, and a ball bearing having a thicker but less loss torque is generally used for both bearings, it is thin. As a result, the brushless motor of the present invention has an effect of reducing the thickness and consuming less current.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a brushless motor according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a brushless motor according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a brushless motor according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view of a first conventional brushless motor.

FIG. 6 is a sectional view of a second conventional brushless motor.

FIG. 7 is a sectional view of a brushless motor of a third conventional example.

[Explanation of symbols]

 11 rotor 12 shaft 13 hub 14 rotor magnet 15 rotor yoke 15a rotor outer peripheral protrusion 16 rotor inner peripheral protrusion 21 stator 22 armature coil 23 stator yoke 23a stator outer peripheral protrusion 24 bearing housing 25 stator substrate 25a substrate outer peripheral protrusion 26 stator middle Projection 31 Sliding bearing 32 Ball bearing

Claims (1)

[Claims] 1. A rotor having a rotor yoke for supporting a rotor magnet on a shaft, a stator having a bearing housing for supporting a stator yoke having an armature coil, and a rotor rotatable with respect to the stator. A brushless motor comprising two supporting bearings, wherein the two bearings are arranged at substantially the same height in the circumferential direction.