Hybrid magnet type DC motor

Details Hybrid magnet type DC motor Hybrid magnet type DC motor

2003-04-04

2004-03-16

Mullins, Burton (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S154280, C310S254100

Reexamination Certificate

active

06707213

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a hybrid magnet type DC motor having a stator that includes a coil and a permanent magnet.
A small motor, which consumes little electricity and brings high level torque, has widely been used in the field of, for example, automobile, office automation hardware, vending machine and medical and welfare equipment. Most of the motors used in these fields are normally comprised of a permanent magnet. This kind of motor has been grown technically and it is difficult to achieve high efficiency, reduction in size and weight and high level torque. Then, a hybrid magnet type DC motor
50
shown in
FIG. 6
has been proposed.
As shown in
FIG. 6
, the DC motor
50
has a cylindrical yoke
55
and an armature
51
that is accommodated in the yoke
55
. The armature
51
has a rotation core
53
that is fitted around a rotation shaft
52
and a plurality of rotation coils
54
that are wound around the rotation core
53
. The rotation core
53
has a plurality of tees
53
a
that radiate in all direction. A stator
56
is fixed to the inner surface of the yoke
55
. The stator
56
includes a pair of electromagnets
57
,
58
and a pair of permanent magnets
59
,
60
and constitutes a hybrid magnet. A prescribed gap is provided between the stator
56
and the outer surface of the armature
51
. The gap is so small that it is not visibly illustrated in FIG.
6
.
The electromagnets
57
,
58
have fixed cores
61
,
62
and fixed coils
63
,
64
that are wound around portions of the fixed cores
61
,
62
. The fixed cores
61
,
62
have at one end pole cores
65
,
66
that are made by semi-cylindrical plates. The fixed coils
63
,
64
are wound around portions of the fixed cores
61
,
62
(the portions shown by broken lines) that radially project from the pole cores
65
,
66
. The pole cores
65
,
66
face to the tees
53
a
of the armature
51
with the prescribed gap in between. The pole cores
65
,
66
have extending portions
65
a
,
66
a
that extend in the circumferential direction of the stator
56
beyond both ends of the corresponding fixed coils
63
,
64
. The outer surfaces of the extending portions
65
a
,
66
a
contact the inner surfaces of the permanent magnets
59
,
60
.
The permanent magnet
59
has two magnet pieces: a first magnet piece
59
a
and a second magnet piece
59
b
, while the permanent magnet
60
has two magnet pieces: a first magnet piece
60
a
and a second magnet piece
60
b
. The magnet pieces
59
a
,
59
b
,
60
a
,
60
b
have a sectorial cross-sectional shape. The magnet pieces
59
a
and
59
b
of the permanent magnet
59
are arranged such that the magnetic direction of the first magnet piece
59
a
is opposite to that of the second magnet piece
59
b
. The magnet pieces
60
a
and
60
b
of the permanent magnet
60
are arranged such that the magnetic direction of the magnet piece first
60
a
is opposite to that of the second magnet piece
60
b
. Specifically, the first magnet pieces
59
a
,
60
a
of the permanent magnets
59
,
60
are magnetized to be an N-pole at their inner surfaces and an S-pole at their outer surfaces. The second magnet pieces
59
b
,
60
b
of the permanent magnets
59
,
60
are magnetized to be an S-pole at their inner surfaces and an N-pole at their outer surfaces. A resin piece T, which functions as a magnetic insulator T, is provided between the first and second magnet pieces
59
a
,
59
b
. Similarly, the resin piece T is provided between the first and second magnet pieces
60
a
,
60
b.
Core plates
67
contact the outer surfaces of the permanent magnets
59
,
60
. The magnetism of the first and second magnet pieces
59
a
,
59
b
,
60
a
,
60
b
passes through the corresponding core plates
67
. The insulators
68
, which are made of resin, are located between the core plates
67
and the fixed yoke
55
. The insulators
68
magnetically insulate the corresponding permanent magnets
59
,
60
from the fixed yoke
55
. Accordingly, magnetic flux, which is produced in the permanent magnets
59
,
60
, passes through the pole cores
65
,
66
.
In the above DC motor
50
, the contacting area of the pole cores
65
,
66
and the permanent magnets
59
,
60
can be increased, which increases torque of the motor
50
, without increasing the diameter of the yoke
55
.
In the above DC motor
50
, however, the magnetic flux produced between the magnet pieces
59
a
,
59
b
of the permanent magnet
59
and the magnet pieces
60
a
,
60
b
of the permanent magnet
60
flows through the corresponding core plates
67
. The insulators
68
are located to prevent the magnet flux from leaking to the yoke
55
. When the magnetism of the permanent magnets
59
,
60
is increased, however, the magnetic flux produced in the permanent magnets
59
,
60
leaks to the yoke
55
through the insulators
68
. Accordingly, the magnetic flux cannot be efficiently used.
The permanent magnets
59
,
60
have the magnet pieces
59
a
,
59
b
,
60
a
,
60
b
and the resin pieces T that magnetically separate the magnet pieces from each other. The DC motor
50
further includes the core plates
67
through which the magnetism from the corresponding magnet pieces permeates and the insulators
68
that magnetically separate the permanent magnets
59
,
60
from the fixed yoke
55
. Thus, the number of parts that constitute the DC motor
50
is increased, which complicates the assembly of the motor
50
.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a hybrid magnet type DC motor in which magnetic flux does not leak much and the structure is simple.
To achieve the above objective, the present invention provides a hybrid magnet type DC motor including a commutation device, an armature, a cylindrical stator and a fixed yoke. The armature has a rotation core and a plurality of rotation coils that are wound around the rotation core. Direct current is supplied to the rotation coils through the commutation device. The cylindrical stator is constituted as a hybrid magnet. The cylindrical stator has a circumferential direction, a radial direction, and an axial direction. The stator has a plurality of electromagnets and permanent magnets that are alternately arranged in the circumferential direction of the stator. Each electromagnet has a fixed core and a fixed coil that is wound around the fixed core. Each fixed core has a pole core that faces to the rotation core and has an approximately arched cross-sectional shape. When direct current is supplied to the fixed coils, the pole cores are alternately magnetized to be N- and S-poles in the circumferential direction of the stator. The fixed yoke through which magnetism permeates is magnetically separated from the permanent magnets and contacts the fixed cores. The permanent magnets are anisotropic magnets. Each permanent magnet includes a first curved surface and a second curved surface opposite to the first curved surface. The first curved surface is magnetized and the second curved surface is non-magnetized. The first curved surface of each permanent magnet contacts two pole cores that are arranged in both sides of each permanent magnet in the circumferential direction of the stator and have different polarities from each other. The first curved surface has an S-pole portion and an N-pole portion. The S-pole portion is provided in one side of the first curved surface in the circumferential direction and the N-pole portion is provided in the other side of the first curved surface in the circumferential direction. The S-pole portion contacts the pole core that is magnetized to be an S-pole and the N-pole portion contacts the pole core that is magnetized to be an N-pole.


REFERENCES:
patent: 3984711 (1976-10-01), Kordik
patent: 6051904 (2000-04-01), Akemakou
patent: 6242834 (2001-06-01), Akemakou
patent: 6342746 (2002-01-01), Flynn
patent: 6563248 (2003-05-01), Fujita
patent: 2002/0084714 (2002-07-01), Fujita
patent: 02-266859 (1990-10-01), None
patent: 2000-150228 (2000-05-01), None
patent: 2002-2

Affiliated with

Also associated with

Rating

Hybrid magnet type DC motor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Hybrid magnet type DC motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hybrid magnet type DC motor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3190980