Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-07-16
2002-08-06
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S0400MM
Reexamination Certificate
active
06429558
ABSTRACT:
FIELD OF TECHNOLOGY
This invention deals with a coreless, miniature motor. In more detail, it deals with improvement of a miniature motor for use in assembly of pagers, mobile telephones and other portable electronic equipment, to serve as a vibration alarm device that rings by vibration.
PRIOR TECHNOLOGY
Vibration alarm devices that ring by vibration instead of ringing by sound have been adopted as alarm devices to notify one of received messages in conferences and other locations where production of a sound is to be avoided.
Conventionally, vibration alarm devices of this sort have used coreless motors that rotate an eccentric weight.
Such a coreless motor has, as shown in
FIG. 9
, an external housing
1
that comprises a cylindrical case
1
a
and caps
1
b
and
1
c
that fit into both ends of the case
1
a
, a central rotating shaft
2
of which one end projects through the cap
1
b
at one end of the case
1
a
and the other end is located within the case
1
a
; the rotating shaft
2
is supported and free to turn within a bearing
3
in the cap
1
b
, and an eccentric weight
4
, a stator
5
and a rotor
6
are assembled on the same axis as the rotating shaft
2
.
Of these, the eccentric weight
4
is fixed on the end of the rotating shaft
2
that protrudes from the external housing
1
beyond the cap
1
b
. The stator
5
is fixed between a bearing
5
a
, which is on the same axis as the rotating shaft
2
and located towards its other (enclosed) end, and a ring
1
d
inside from the cap
1
b
through which the rotating shaft
2
is inserted; the stator
5
is an assembly of field magnets in the form of a hollow cylinder with the rotating shaft
2
as its central axis. The rotor
6
has a cylindrical coil
6
a
located, with intervening spaces, between the field magnets
5
b
and the case
1
a
of the external housing
1
. The coil
6
a
is assembled so as to turn together with the rotating shaft
2
, by means of support by a support plate
6
b
that is between the bearing
5
a
of the field magnets
5
b
and the other (enclosed) end of the rotating shaft
2
.
In addition, there is a commutator
7
on the same axis between the support plate
6
b
of the coil
6
a
and the other (enclosed) end of the rotating shaft
2
, as well as a brush mount (not illustrated) on the cap
1
c
for the brush
8
, and a lead wire
9
that connects the brush
8
to a battery or other power source.
The eccentric weight
4
mounted on the axis that protrudes outside the external housing
1
of this coreless motor presents a major obstacle to efforts to make portable electronic equipment such as pagers and mobile telephones smaller and lighter. The external housing
1
is essential to the structure of the coreless motor described above, and in addition to the size of the external housing, a case must be formed between it and the coil
6
a
, so the external housing
1
is another obstacle to efforts to reduce size and weight. Moreover, because the eccentric weight
4
spins about with support on one side, the load of the spinning is particularly heavy on the bearing
3
, and a loss of torque occurs. Moreover, if the equipment undergoes a fall or shock, the heaviness of the weight
4
can bend the rotating shaft
2
; it is not possible to make the shaft
2
with a very small diameter.
In addition to the eccentric weight and the external housing discussed above, there are other problems with the structure of the brushes of the conventional coreless motor.
A round wire or ribbon wire that is straight or bent in a U-shape with the base welded to a brush holder is generally used as the brush. Two brushes are mounted so as to press like springs, from both sides, against the commutator
7
that is mounted on the same axis as the rotating shaft
2
. Because of the overall length and the mounting, a large assembly space is required. Moreover, if the outer diameter of the commutator
7
is reduced along with that of the rotating shaft
2
, it becomes difficult to adjust the pressure accurately and the length of the springs is no longer adequate, so this is not desirable as a brush for use with a miniature coreless motor.
The same sort of problems are manifest in the structure of a gyro motor. For this reason there is a desire for coreless miniature motors, including gyro motors, that meet the conditions of small size, light weight, excellent shock resistance, and good precision. There are limits, however, to motors that rotate with eccentric weights.
PRESENTATION OF INVENTION
The purpose of this invention is to provide a coreless miniature motor, including vibrating coreless motors and gyro motors, with superior portability in terms of small size and light weight, that can function as a weight or flywheel that produces rotary vibration without relying on rotation of an eccentric weight supported on one side by a rotating shaft.
An additional purpose of this invention is to provide a coreless miniature motor that can be built without an external housing, and which costs less, is easily assembled and well-suited to mass production.
Moreover, it is a purpose of this invention to focus on the structure of brush attachment, and to provide a coreless miniature motor with small, high-performance brushes that have a fully effective length even when used with commutators of small diameter.
One more purpose is to provide a coreless miniature motor with superior shock resistance, and other features of this invention will become clear through the following detailed explanation.
REFERENCES:
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patent: 5327035 (1994-07-01), Sunaga
patent: 5341057 (1994-08-01), Yamaguchi et al.
patent: 5373207 (1994-12-01), Yamaguchi et al.
patent: 5621260 (1997-04-01), Fukuoka et al.
patent: 5889349 (1999-03-01), Yasuda
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patent: 7-284243 (1995-10-01), None
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International Search Report dated Dec. 22, 1998.
Namiki Seimitsu Houseki Kabushiki Kaisha
Nguyen Tran
Robinson Eric J.
Robinson Intellectual Property Law Office PC
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