Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-03-20
2001-03-13
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156030, C310S261100
Reexamination Certificate
active
06201335
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotor structure for an AC generator or a motor and, particularly, to a structure for attaching magnets for preventing the leakage of a magnetic flux between claw-like magnetic poles.
2. Description of the Prior Art
FIG. 17
is a sectional side view of a prior art rotor structure for an AC generator or a motor,
FIG. 18
is a perspective view of the rotor, and
FIG. 20
is an exploded side view of individual parts of the rotor.
As shown in
FIG. 17
, this generator comprises a case
3
consisting of an aluminum front bracket
1
and an aluminum rear bracket
2
, a shaft
6
which is installed in the case
2
and one end of which is fitted with a pulley
4
, a Randle type rotor
7
fixed to the shaft
6
, fans
5
fixed to both end surfaces of the rotor
7
, a stator
8
fixed to the inner wall of the case
3
, slip rings
9
which are fixed to the other end of the shaft
6
and supply a current to the rotor
7
, a pair of brushes
10
in sliding contact with the slip rings
9
, a brush holder
11
for storing the brushes
10
, a rectifier
12
which is electrically connected to the stator
8
and rectifies an alternating current generated in the stator
8
into a direct current, a heat sink
19
attached to the brush holder
11
, and a regulator
20
which is attached to the heat sink
19
and regulates an AC voltage generated in the stator
8
.
The rotor
7
comprises a cylindrical rotor coil
13
for generating a magnetic flux with a current and a pole core
14
which covers the rotor coil
13
and forms a magnetic pole with the magnetic flux of the rotor coil
13
.
The stator
8
comprises a stator core
15
and a stator coil
16
which is wound round the stator core
15
and generates an alternating current by a change in magnetic flux from the rotor coil
13
caused by the rotation of the rotor
7
.
The pole core
14
consists of a first pole core body
21
and a second pole core body
22
which are mated with each other.
The pole core body
21
and the pole core body
22
are generally made from iron and consist of cylindrical portions
21
e
and
22
e
wound with the rotor coil
13
and disk-like base portions
21
k
and
22
k
from which the cylindrical portions
21
e
and
22
e
project, respectively. The base portions
21
k
and
22
k
have at the peripheries a plurality of claw-like magnetic poles
23
and
24
which are mated with each other between the outer wall of the rotor coil
13
and the inner wall of the stator
8
, respectively.
The thickness and width of each of the claw-like magnetic poles
23
and
24
are large on the base portion
21
k
and
22
k
sides and become smaller toward the end sides.
The inner faces
23
a
and
24
a
of the claw-like magnetic poles
23
and
24
become thinner toward the ends and the outer faces
23
b
and
24
b
are arched in conformity with the inner wall of the stator
8
. Each of the claw-like magnetic poles
23
and
24
has two trapezoidal side faces
23
c
and
24
c
in a circumferential direction of the rotor
7
. Since each pair of claw-like magnetic poles
23
and
24
are mated with each other, the inner faces
23
a
and
24
a
of the claw-like magnetic poles
23
and
24
are arranged alternately in a circumferential direction. The side faces
23
c
and
24
c
of the claw-like magnetic poles
23
and
24
are inclined toward the centers of the claw-like magnetic poles
23
and
24
so that they become thinner from the root side toward the end side.
As shown in
FIG. 18
, a rectangular magnet
30
A magnetized to suppress the leakage of a magnetic flux between the opposed side faces
23
c
and
24
c
is fixed between the adjacent claw-like magnetic poles
23
and
24
.
A description is subsequently given of the operation of the generator. A current is supplied from an unshown battery to the rotor coil
13
through the brushes
10
and the slip rings
9
to generate a magnetic flux, whereby the claw-like magnetic poles
23
of the first pole core body
21
are magnetized to an N pole and the claw-like magnetic poles
24
of the second pole core body
22
are magnetized to an S pole. Meanwhile, the pulley
4
is turned by the rotation force of an engine and the rotor
7
is turned by the shaft
6
, thereby generating electromotive force in the stator coil
16
. This AC electromotive force is rectified into a direct current by the rectifier
12
, regulated by the regulator
20
and charged into the unshown battery.
The above magnet
30
A which is inserted between the claw-like magnetic poles
23
and
24
and is rectangular or may be various in shape, for example, ring-shaped or ring-shaped and packed in other resin is fixed to the claw-like magnetic poles
23
and
24
by fixing means.
However, the following problems may occur. That is, since stress is applied to the magnet
30
A at the time of production or centrifugal force generated by rotation is applied to the magnet
30
A, the magnet
30
A is inferior in durability.
Further, since the pole core bodies
21
and
22
are generally produced by forging, details of the claw-like magnetic poles
23
and
24
which have a specially complex shape cannot have high accuracy. There are differences in size between the claw-like magnetic poles
23
and
24
. It is difficult to manufacture the magnet
30
A which is formed in conformity with the inner faces
23
a
and
24
a
of the claw-like magnetic poles
23
and
24
which differ from each other and a support member which is molded in conformity with the claw-like magnetic poles
23
and
24
.
When the magnet
30
A is manufactured in consideration of molding ease, it becomes fragile. Therefore, when it is installed near the claw-like magnetic poles
23
and
24
of the rotor
7
, some measure is necessary. However, when the magnet
30
A is made sufficiently thick or very strong, it costs dear, making it difficult to mass-produce it.
Suppose that the magnet
30
A and the support member are produced in accordance with the differences and that differences in the gaps between the claw-like magnetic poles
23
and
24
and the magnet
30
A and between the claw-like magnetic poles
23
and
24
and the support member are made small. Even if the differences are small, when the magnet
30
A receives centrifugal force at the time of the rotation of the rotor
7
, a great force difference is produced, thereby making it possible that the magnet
30
A and the support member are damaged.
When the magnet
30
A is supported by the side faces
23
C and
24
c
of the claw-like magnetic poles
23
and
24
irrespective of the inner faces
23
a
and
24
a
of the claw-like magnetic poles
23
and
24
, force may be applied to the magnet
30
A by the dislocation of each of the two pole core bodies
21
and
22
when they are mated with each other or dislocation caused by rotation force.
The end portions of the claw-like magnetic poles
23
and
24
are moved toward the rotor coil
13
and the stator
8
by centrifugal force generated by the rotation of the rotor
7
and the magnetic attraction force of the stator
8
at the time of power generation. Thereby, a load is applied to the magnet
30
A between the claw-like magnetic poles
23
and
24
, whereby the magnet
30
A may be distorted or broken.
A countermeasure against this is disclosed by Japanese Laid-open Patent Application No. 11-136913. In this publication, a magnet
30
B is formed as shown in FIG.
19
and FIG.
20
. That is, the magnet
30
B is fixed to each of the claw-like magnetic poles
23
and
24
in such a manner that it covers the inner face
23
a
or
24
a
and the side faces
23
c
or
24
c
of the claw-like magnetic pole
23
or
24
. A space
25
is formed between adjacent magnets
30
B. Thereby, a set of the claw-like magnetic pole
23
and the magnet
30
B and a set of the claw-like magnetic pole
24
and the magnet
30
B move independently, thereby preventing the application of a load to the magnet
30
B and the breakage of the magnet
30
B.
SUMMARY OF THE INVENTION
However, the
Asao Yoshihito
Higashino Kyoko
Oohashi Atsushi
Tsuruhara Kenji
Mitsubishi Denki & Kabushiki Kaisha
Mullins Burton
Sughrue Mion Zinn Macpeak & Seas, PLLC
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