JPH09261909A - Rotor exposed type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent foreign matter from entering an air gap which forms a magnetic circuit with a simple structure, in a motor exposed type motor. SOLUTION: A foreign matter entrance preventing means is fitted at the outer position than an air gap A which forms a magnetic circuit through a clearance B. This means can be attained by forming a rotor R and a stator S into an axial air gap type and raising a wall 7 to the outside of the rotor so that the axial air gap A and the diametrical air gap A may be invisible from the stator side, or lowering a skirt part from the magnet case of the rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved rotor exposure type motor, and more particularly to a CDROM spindle motor or the like which can prevent foreign matter from entering a magnetic circuit space.

[0002]

2. Description of the Related Art Conventionally, as a CDROM spindle motor, there is a CDROM spindle motor in which a rotor portion R is covered with an outer housing H so as not to be exposed to the outside, as shown in a sectional view of an essential portion of FIG. However, with the recent trend toward thinning, a rotor-exposed spindle motor has no choice but to remove the outer housing whose thickness is a problem. As this rotor exposure type motor, the one shown in FIG. 5 is generally used. That is, the circuit board 22 on which a predetermined circuit pattern is formed is arranged on the bracket 11 in which the bearing holder 66 is integrated, and the plurality of air-core armature coils 3 and 3 are fixed to the circuit board 22 and the field magnet MM. The rotor R formed by press-fitting the magnet case Y, which also functions as the integrated yoke, to the shaft S, is attached to the air-core armature coil 33.
On the other hand, the bearing 44 is rotatably supported by the bearing 44 arranged in the bearing holder 66 through a predetermined space A.

[0003]

However, in the motor having such a structure, the rotor is directly exposed to the outside, and the field magnet itself has to be made of a strong rare earth element. It is easy to suck magnetic powder such as iron powder, and foreign matter such as iron powder may enter the voids and lock.

SUMMARY OF THE INVENTION An object of the present invention is to prevent foreign matter from entering a gap forming a magnetic circuit with a simple structure in a rotor exposure type motor.

[0005]

The above problems can be solved by providing foreign matter intrusion preventing means outside the gap forming the magnetic circuit of the gap.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention,
The rotor and the stator are configured in an axial gap type, and a wall is formed outside the rotor as the means so that the axial gap is not visible from the stator side in the radial direction.
As another form, the skirt portion may be lowered from the rotor as the means to cover the gap forming the magnetic circuit. The gap formed by the means is preferably smaller than the gap forming the magnetic circuit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the structure of a first embodiment of the present invention in which the rotor exposed type motor is axially air-gap type will be described with reference to a longitudinal sectional view of a main portion shown in FIG. In the figure, reference numeral 1 is a stator base made of a silicon steel plate, and a plurality of reinforcing skeleton pieces 1a are provided at the center.
.. is started up and a thin circuit board 2 made of a flexible board is attached to the upper surface. A plurality of air-core armature coils 3 are further mounted on the upper surface of the circuit board 2, and the terminals thereof are soldered to a predetermined circuit pattern (not shown). The skeleton piece 1a ...
A hollow bearing 4 is housed inside of, and is integrally provided as a bearing holder portion 6 together with the air-core armature 3 by a resin 5. Further, a wall 7 which is a feature of the present invention is integrally erected in a ring shape on the outermost side by the same resin 5. When integrally molded in this way, the squareness of the hollow bearing 4 with respect to the stator 1 can be finished with extremely high precision using a molding die. The rotor R combined with such a stator has a shaft 8 rotatably supported by the hollow bearing 4.
And a magnet case 9 also serving as a yoke fixed to the shaft 8 and a field magnet M fixed to the magnet case 9 and facing the air-core armature coil through a predetermined air gap A. The outer periphery of the magnet case 9 is arranged inside the stator-side wall 7 with a gap B smaller than the gap A.

In this way, the air gap A is invisible from the radial direction due to the wall 7, and iron powder or the like is contained in the field magnet M.
Will be attracted to the leakage magnetic flux of and will not enter the air gap A.

The wall 7 may be extended upward as shown by an imaginary line so that a part of the wall 7 is loosely fitted on the medium mounting turntable T.

FIG. 2 is a sectional view of the essential portions of the second embodiment, in which the rotor R to the magnet case 99 are skirt-shaped 9.
9a, the armature coil 31 forming the stator is covered, and the gap BB is also smaller than the gap A. In this way, the leakage magnetic flux is hardly emitted to the outside, and there is no fear of sucking iron powder or the like. In addition, as a modified example of lowering the skirt from the rotor side, the rotor and the media chuck turntable are integrated,
The skirt may be removed from this turntable and the same as above.

[0011]

As described above, according to the present invention, foreign matter such as iron powder can be prevented from invading the air gaps forming the magnetic circuit with the simple structure as described above, and therefore, the member such as the outer housing is not required, so that the low posture is achieved. It is possible to provide a rotor exposure type motor.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of a rotor exposure type motor of the present invention.

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

FIG. 3 is a sectional view of a main part of a conventional general spindle motor.

FIG. 4 is a cross-sectional view of essential parts of another embodiment of the same motor of the present invention in the same modified example.

FIG. 5 is a sectional view of a main part of a conventional rotor exposure type motor.

[Explanation of symbols]

 1 Stator Base 1a Reinforcement Lamb 2 Circuit Board 3,31 Air-Core Armature Coil 5 Resin 4 Hollow Bearing 6 Bearing Holder 7 Wall 8 Shaft 9, 99 Magnet Case 99a Skirt M Magnet A Gap B, BB Gap

Claims (4)

[Claims] 1. A rotor-exposed motor having a rotor, at least a part of which is exposed, and a stator, which faces this rotor through a gap, wherein the gap is located outside a gap forming a magnetic circuit. Exposed rotor motor equipped with foreign matter intrusion prevention means. 2. The rotor and the stator are configured as an axial gap type, and a wall is formed outside the rotor as the means so that the axial gap is not visible from the stator side in the radial direction. The exposed rotor type motor according to 1. 3. The rotor according to claim 1, wherein the rotor and the stator are configured as an axial gap type, and the skirt portion is lowered from the rotor side as the means to cover the gap forming the magnetic circuit. Exposed motor. 4. The rotor-exposed motor according to claim 1, wherein the gap formed by the means is smaller than the magnetic circuit portion gap.