Motor having stator with L-shaped salient poles

Details Motor having stator with L-shaped salient poles Motor having stator with L-shaped salient poles

2002-05-22

2003-12-09

Nguyen, Tran (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S216006, C310S216055, C310S06700R

Reexamination Certificate

active

06661150

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority of Japanese No. 2001-155214, filed May 24, 2001, the complete disclosure of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a thin outer rotor type brushless motor for use in a device to rotatably drive flexible discs, CD's and the like and, more particularly, relates to a configuration of an armature core of the brushless motor.
b) Description of the Related Art
An outline of an armature core and a magnet portion of conventional motor
100
is shown in
FIG. 6
with a cross section of one-half from the center.
In armature core
101
, a plurality of pole teeth
102
are formed radially and a coil
103
is wound up in each of pole teeth
102
.
Armature core
101
is mounted on the base
104
through a spacer
105
so as not to touch the base
104
directly.
A ring-shaped magnet
106
is concentric with the armature core
101
and is fixed on the outer circumference of disc
108
which can rotate with a rotating shaft
107
in the center which is supported on the base
104
.
The clearance between an internal circumferential surface
106
a
and an outer circumferential surface
109
a
of salient poles
109
which are the tip of pole teeth
102
has a constant opening (air gap).
c) Problems to be Solved by the Invention
However, as miniaturization of a computer progresses, a small size of a disc drive device is expected and a motor for use in the above device is required to form a thin motor shape.
On the other hand, if the armature core
101
is made thin, magnetic flux H passing through the salient poles
109
of the armature core
101
decreases. Thus, the torque of a motor is reduced.
Additionally, if a wire size of coil
103
is made small in order to make the coil
103
thin, electric resistance increases so that current decreases and the torque of a motor is also reduced.
Furthermore, because a magnetic flux depends upon the number of turns of coil
103
, a method for reducing the number of turns and the thickness also reduces the torque of the motor.
On the other hand, even if the magnetic force of the magnet is strengthened in order to reinforce the torque, the cross section of the armature core
101
is small so that magnetic flux passing therethrough causes saturation. Thus, enhancement of the magnetic force does not result.
OBJECT AND SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to offer a motor that has thinness and can provide a large torque.
In order to achieve the above object, a motor according to the present invention, fundamentally, a base to support rotatably with a rotor, a ring-shaped magnet having a magnetic pole segment which is S-pole shaped and a magnetic pole segment which is N-pole shaped are magnetized alternately in the circumferential direction, the ring-shaped magnet is fixed on the rotor, an armature core in which a plurality of pole teeth are formed radially and a coil is wound up in each of the pole teeth and the armature core which is mounted on the base to face an internal circumference of the ring-shaped magnet.
In the motor, first salient poles of the armature core, the tip of the first salient poles faces the ring-shaped magnet through an opening in the circumferential direction, second salient poles of the armature core, which extend in the circumferential direction from the tip of the second salient poles, which face the ring-shaped magnet through an opening in the axial direction.
In the ring-shaped magnet, the magnetic pole segment facing the first salient poles and the magnetic pole segment facing the second salient poles are magnetized by the same pole.
Furthermore, notching parts are formed on the base, into which notching parts of the armature core fits notching parts and the second salient poles of said armature core are fastened on the internal circumferential surface of the notching parts.
As described above, the motor according to the present invention can be thin and the area of the salient poles of the armature core facing the ring-shaped magnet can be made broadly so that the magnetic force of the ring-shaped magnet is stronger than that of the conventional motor.
Thus, the magnetic flux increases and can strengthen the motor torque.


REFERENCES:
patent: 4902941 (1990-02-01), Merkle et al.
patent: 4949000 (1990-08-01), Petersen
patent: 5500780 (1996-03-01), Boutaghou et al.
patent: 5604389 (1997-02-01), Nitta et al.
patent: 5670837 (1997-09-01), Boutaghou et al.
patent: 6013965 (2000-01-01), Suzuki et al.
patent: 6104114 (2000-08-01), Takeda et al.
patent: 2158654 (1985-11-01), None
patent: 03-003642 (1991-01-01), None
patent: 06-296353 (1994-10-01), None

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