Motor

Details Motor Motor

1999-12-06

2001-11-13

Mullins, Burton S. (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S266000, C310S257000, C310S041000

Reexamination Certificate

active

06316851

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a super-compact motor.
2. Related Background Art
Among compact motors, there is a compact cylindrical stepping motor as shown in FIG.
15
.
In
FIG. 15
, a motor as shown includes two stators
102
arranged in an axial direction, and each stator has two stator yokes
106
opposed to each other in the axial direction. For each stator
102
, a stator coil
105
is coaxially wound around a bobbin
101
held by two stator yokes
106
. Each bobbin
101
on which the stator coil
105
is wound is pinched between and secured by two stator yokes
106
from the axial direction. Each stator yoke
106
is provided with stator teeth
106
a,
106
b
arranged alternately. On the other hand, a pair of stator yokes
106
having stator teeth
106
a,
106
b
are secured to a case
103
of each stator
102
. In this way, the stators
102
are constructed.
A flange
115
and a bearing
108
are secured to one (left one) of two cases
103
, and an opposite bearing
108
is secured to the other case
103
. A rotor
109
has a construction in which a rotor magnet
111
is secured to a rotor shaft
110
. Air gaps are defined between an outer peripheral surface of the rotor magnet
111
and inner peripheral surfaces of the stator yokes
106
of the stators
102
. The rotor shaft
110
is rotatably supported by two bearings
108
secured to the cases
103
.
FIG. 17
is a plan view of a stepping motor for driving a single coil such as used in a watch and the like. In
FIG. 17
, the reference numeral
201
denotes a stator comprised of a permanent magnet; numerals
202
,
203
denote stators: and numerals
204
denote a coil.
However, in the conventional compact stepping motor shown in
FIG. 15
, since the cases
103
, bobbins
101
, stator coils
105
and stator yokes
106
are concentrically arranged around the rotor, the entire dimension of the motor becomes great. Further, as shown in
FIG. 16
, since magnetic flux generated by energization of the stator coil
105
mainly passes through an end face
106
a
1
of the stator tooth
106
a
and an end face
106
b
1
of the stator tooth
106
b
, the magnetic flux does not act on the rotor magnet
111
effectively, with the result that high output of the motor cannot be obtained.
Also regarding the motor shown in
FIG. 17
, magnetic flux generated by energization of the coil
204
is concentrated into the smallest gap between the rotor
201
and the stator
202
and does not act on the magnet effectively.
The inventors have proposed a motor solving the disadvantage of the conventional motor shown in
FIG. 15
, as disclosed in U.S. Pat. No. 5,831,356.
In this proposed motor, a cylindrical rotor comprises permanent magnets equidistantly disposed in a circumferential direction and having alternate magnetic poles; a first coil, a rotor and a second coil are sequentially disposed in an axial direction of the rotor; a first outer magnetic pole and a first inner magnetic pole, which are excited by the first coil, are opposed to outer and inner peripheral surfaces of the rotor and a second outer magnetic pole and a second inner magnetic pole, which are excited by the second coil, are opposed to the outer and inner peripheral surfaces of the rotor; and a rotary shaft (rotor shaft) is extended from the interior of the cylindrically arranged permanent magnets.
Although such a motor can have high output and small outer dimension, since the diametrical dimensions of the inner magnetic poles are small, it is difficult to manufacture magnetic teeth. Further, it has been requested that stable output having no vibration be obtained from a motor having a small diametrical dimension.
To this end, the inventors have recently proposed a motor in which inner magnetic poles have a configuration having good workability, as described in U.S. patent application Ser. No. 08/994,994, and also proposed a rotor in which output transmitting means, such as a gear or a pulley, can easily be attached to a rotary shaft having a small diametrical dimension and stable output having no vibration can be obtained, as described in U.S. patent application Ser. No. 09/022,474.
Recently, it has been requested to provide a motor having high output and super-compact size.
To this end, the inventors have recently proposed a motor constructed as a single phase motor to achieve high output and super-compact size, as described in U.S. patent application Ser. No. 09/293,063.
In recent years, it has been requested that such a motor having high output and super-compact size made be further highly accurate.
SUMMARY OF THE INVENTION
The present invention aims to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a single-phase motor wherein a wide space within which a coil is wound is maintained to achieve higher output.
Another object of the present invention is to provide a motor in which a small diameter portion having a diameter smaller than of an inner magnetized pole portion is provided on an inner yoke and a coil is wound around the small diameter portion.
The other objects and features of the present invention will be apparent from the following detailed explanation.


REFERENCES:
patent: 4004165 (1977-01-01), Haydon
patent: 4097833 (1978-06-01), Myers
patent: 4644211 (1987-02-01), Idogaki et al.
patent: 4928028 (1990-05-01), Leibovich
patent: 5384506 (1995-01-01), Aoshima
patent: 5831356 (1998-11-01), Aoshima
patent: 5925945 (1999-07-01), Aoshima
patent: 5945753 (1999-08-01), Maegawa et al.
patent: 5969453 (1999-10-01), Aoshima
patent: 5973425 (1999-10-01), Aoshima
patent: 6081053 (2000-06-01), Maegawa et al.

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