JPH07231634A - Radial gap spindle motor - Google Patents

Abstract

PURPOSE:To obtain a radial gap spindle motor in which the vertical movement and the radial displacement of the rotor are prevented to protect bearings from wear so that its service life is elongated. CONSTITUTION:A field magnet 44 is faced with a stator 3 which is formed by winding an armature coil 2 on a plurality of salient-pole cores 2. The field magnet 44 is held by a rotor core 5, and it is supported by a bracket 9 so as to be freely rotatable via a shaft 6 and bearings 7, 8. The tip of the shaft 6 is pivot-supported by a housing 11 via a slider. A magnet 45 for energization is arranged in the rotor case 5 or the housing 11 in such a way that an energization force which pivot-supports the shaft 6 is provided with a component in the radial direction in addition to a component in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a radial gap type spindle motor used for driving a CD-ROM or the like.

[0002]

2. Description of the Related Art Conventionally, a radial gap type spindle motor as shown in FIG. 4 has been known. That is, a stator 3 in which an armature coil 2 is wound around a plurality of salient pole cores 1, a field magnet 4 facing the stator 3 via a radial gap, and the field magnet 4 are attached to a rotor case 5. A bracket 9 which is rotatably supported by a shaft 6 and bearings 7 and 8 and which holds the stator 3; and a housing 11 which pivotally supports the tip of the shaft 6 at a bottom via a slider 10. Become.

In order to prevent the rotor portion from moving up and down, the centers of the salient pole core 1 and the field magnet 4 are intentionally shifted to urge the rotor portion downwardly of the housing, and the slider 10 is pushed by the tip of the shaft 6. I'm trying to get the pivot support.

[0004]

However, in such a structure, when the magnetic force of the field magnet 4 is weak, the biasing force is insufficient, and when rotating, a shock or the like causes up and down movement and becomes unstable. For this reason, it is usually used in a rare earth magnet or the like which is stronger than necessary, but this increases the cost and causes the problem of cogging torque. Also CD,
In a spindle motor that drives an MD (mini disk) or the like, a radial force (lateral pressure) does not act on the shaft, so that the bearing is likely to be greatly worn due to shaft shake and scoring phenomena. This phenomenon occurs because the oil-impregnated bearing has little pumping action and oil lubrication is difficult to occur.
The shaft shake due to the wear of the bearing is a fatal defect in driving a medium such as a CD.

[0005]

It is an object of the present invention to prevent the rotor from moving up and down by obtaining an appropriate biasing force with a simple structure. Another object of the present invention is to prevent radial deviation of the shaft, prevent wear of the bearing, and obtain a long life. Yet another object of the present invention is to achieve the above problems without increasing the posture.

[0006]

A first basic object of the present invention is to provide a radial gap type spindle motor having the above-described structure, in which the biasing force for pivotally supporting the shaft has a radial direction component in addition to the axial direction. Can be achieved by arranging the biasing magnet in the rotor case or housing so that

The second object of the present invention can be achieved by arranging the urging magnet on the outer peripheral portion of the bottom surface of the rotor case and making the magnetic force unbalanced as a means having a radial direction component.

The third object of the present invention can be achieved by forming a resin passage hole in the outer peripheral portion of the bottom surface of the rotor case and integrally forming the biasing magnet with the field magnet.

The fourth object of the present invention can be achieved by disposing the biasing magnet on one side of the housing.

[0010]

According to the means for achieving the first basic problem of the present invention, the shaft tip can be stably pivotally supported on the housing by the magnetic force of the biasing magnet irrespective of the magnetic force of the field magnet, and the radial direction can be obtained. The urging force prevents the shaft from shaking, and the lateral pressure in the radial direction provides the pumping function of the oil-impregnated bearing.

According to the second object achieving means of the present invention,
It can be easily achieved by magnetizing operation without breaking dynamic balance.

According to the third object achieving means of the present invention,
Since the field magnet and the urging magnet can be integrally formed, the work for attaching the urging magnet can be omitted and the accuracy is improved, so that the cost can be reduced and the quality can be improved.

According to the fourth object achieving means of the present invention,
Since the biasing magnets may be arranged at a part of the corner inside the housing, the structure becomes simple.

[0014]

[First Embodiment] FIG. 1 is a sectional view of the essential portions of a first embodiment of the present invention. That is, a stator 3 formed by winding an armature coil 2 around a plurality of salient pole cores 1, a field magnet 44 facing the stator 3 via a radial gap, and the field magnet 44 including the field magnet 44. Shaft 6 held via
Is rotatably supported by bearings 7 and 8, and includes a bracket 9 for holding the stator 3 and a housing 11 in which the tip of the shaft 6 is pivotally supported by a slider 10.

The outer peripheral portion of the bottom surface of the rotor case 5 is stepped, a plurality of resin passage holes 5a are provided, and the field magnet 44 and the biasing magnet 45 disposed on the stepped portion 5b are made of resin. The magnet is integrally formed.

The urging magnet 45 is arranged in a ring shape around the entire circumference and is magnetized only on one side so that the magnetic force is unbalanced.

In this way, the biasing magnet 45
Is attracted to the housing, but a biasing force in the axial direction is obtained without destroying the dynamic balance of the rotor part, and a biasing component is also generated in the radial direction due to biasing on one side. Therefore, the shaft 6 will not be shaken, and the oil pumping function will be normal.

[0018]

[Second Embodiment] FIG. 2 is a cross-sectional view showing the structure of a second embodiment of the present invention. The urging magnet 46 is a small piece, and the rotor case 5 has a small amount on the outer periphery of the bottom surface. It is attached to the crushed step portion 5bb by adhesion or the like. By doing so, the cost of the biasing magnet 46 becomes very low, and there is no risk of the dynamic balance being severely disrupted. In this embodiment, the other components are the same as those in the first embodiment, so the same reference numerals are given and the description thereof is omitted.

[0019]

[Third Embodiment] FIG. 3 is a sectional view showing the structure of a third embodiment of the present invention, in which a crescent-shaped biasing magnet 47 is arranged on the housing 11 side. .
By doing so, the structure on the rotor side is simplified, and since there is the step portion 5b on the outer circumference of the rotor case 5, there is no particular need to thicken the posture. Although the crescent-shaped urging magnet 47 is arranged on one side of the housing 11 in this embodiment, it is possible to exhibit the same effect as having a radial component even if only one side is magnetized into a ring magnet. There is no end.

[0020]

Other Embodiments In each of the above embodiments, the biasing magnets 45, 46 and 47 are arranged at the maximum portion in the radial direction in order to effectively exert the biasing force of the radial component. However, the present invention is not limited to this, and a relatively strong urging magnet may be arranged in the space of the step portion 5c inside the rotor case 5 formed by winding the armature coil, for example, on the rotor case side or the housing side. Good. In this case, it goes without saying that the magnetic force is unbalanced.

[0021]

According to the above configuration of the present invention, the shaft can be prevented from moving up and down with a simple structure in which a biasing magnet is added, and the radial component also generates a biasing force. The blurring of the can be prevented. For this reason, since the lateral pressure is always applied, even if a lateral pressure medium such as a CD or MD is driven, it is possible to prevent the bearing from being worn, and it is possible to obtain a long service life. Moreover, since the space for arranging the biasing magnet uses an unnecessary dead space which is inevitably formed by winding the armature coil, there is no fear of raising the posture.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of a radial gap type spindle motor of the present invention.

FIG. 2 is a sectional view of an essential part of a second embodiment of the motor of the present invention.

FIG. 3 is a cross-sectional view of essential parts of a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a conventional radial gap type spindle motor.

[Explanation of symbols]

 1 salient pole core 2 armature coil 3 stator 44 field magnet 5 rotor case 6 shaft 7, 8 bearing 9 bracket 10 slider 11 housing 45, 46, 47 energizing magnet

Claims (4)

[Claims] 1. A stator comprising an armature coil wound around a plurality of salient pole cores, a field magnet facing the stator via a radial gap, and the field magnet held via a rotor case. In a radial gap type spindle motor comprising a shaft, a bracket that rotatably supports the shaft via a bearing and holds the stator, and a housing that pivotally supports the tip of the shaft via a slider. A radial gap type spindle motor in which a biasing magnet is arranged in the rotor case or housing so that the biasing force for supporting the pivot has a radial direction component in addition to the axial direction. 2. The radial gap type spindle motor according to claim 1, wherein the biasing magnet is arranged on the outer peripheral portion of the bottom surface of the rotor case, and the magnetic force is unbalanced as a means having a radial direction component. 3. The radial gap type spindle motor according to claim 2, wherein a resin through hole is provided in the outer peripheral portion of the bottom surface of the rotor case, and the biasing magnet and the field magnet are integrally molded with the resin. 4. The radial gap type spindle motor according to claim 1, wherein a biasing magnet is arranged on one side of the housing.