Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-01-04
2002-04-09
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156720, C310S156660, C310S052000
Reexamination Certificate
active
06369485
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. 13
is a sectional side view showing the constitution of a conventional rotor structure for an AC generator or a motor,
FIG. 14
is a perspective view showing the constitution of this rotor,
FIG. 15
is an exploded side view of individual parts of the rotor, and
FIG. 18
is a sectional view in a radial direction of the claw-like magnetic poles of the rotor.
As shown in
FIG. 13
, 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 stator
8
comprises a stator core
15
and a stator coil
16
which is wound around the stator core
15
and which generates an alternating current by a change in magnetic flux from a rotor coil
13
caused by the rotation of the rotor
7
.
The rotor
7
comprises the 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 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 their peripheries a plurality of claw-like magnetic poles
23
and
24
which mate 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 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
are arched in conformity with the peripheral surface of the rotor coil
13
and the outer faces
23
b
and
24
b
of the claw-like magnetic poles
23
and
24
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
.
As shown in
FIG. 14
, 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 ring-shaped magnet and a ring-shaped magnet packed in other resin are available in addition to the rectangular magnet
30
A to be inserted between the 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
. The electromotive force of this, alternating current is rectified into a direct current by the rectifier
12
, regulated by the regulator
20
and charged into the unshown battery.
However, the following problem may occur. That is, 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 at about 10,000 to 15,000 rpm.
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. 16
, FIG.
17
and FIG.
19
. 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 faces
23
a
and
24
a
and the side faces
23
c
and
24
c
of the claw-like magnetic poles
23
and
24
. A space
25
is formed between the 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, in the prior art generator, as shown in
FIG. 19
, the magnets
30
B are provided for the claw-like magnetic poles
23
and
24
in such a manner that they cover the inner faces
23
a
and
24
a
and side faces
23
c
and
24
c
of the claw-like magnetic poles
23
and
24
. Therefore, as shown in
FIG. 18
, compared with the rectangular magnet
30
A interposed between the adjacent claw-like magnetic poles
23
and
24
, the claw-like magnetic poles
23
and
24
are not cooled well because the magnets
30
B surround the claw-like magnetic poles
23
and
24
.
Therefore, the coolability of the magnet
30
B deteriorates and the temperature of the magnet
30
B rises, thereby reducing magnetic force. Further, when the temperature rises and becomes higher than the thermal deformation temperature of the magnet
30
B, the magnet
30
B is broken.
The present invention which has been made to solve the above problems improves the coolability of magnets provided to suppress the leakage of a magnetic flux between claw-like magnetic poles and prevents a reduction in magnetic force to suppress deterioration in the output of an AC generator.
According to a first aspect of the present invention, there is provided a rotor structure comprising a rotor coil for generating a magnetic flux with a current, a pole core which is provided to cover the rotor coil and consists of a first pole core body and a second pole core body, each having claw-like magnetic poles which are situated to mate with each other at positions where they cover the peripheral surface of the rotor coil, magnets which are provided on both sides of each of the claw-like magnetic poles and suppress the leakage of a magnetic flux between the side faces of the adjacent claw-like magnetic poles, and metal holding members each of which fixes the magnets to each of the claw-like magnetic poles in such a manner that it covers the magnets together with the claw-like magnetic pole and radiates heat transmitted to the claw-like magnetic pole at the time of power generation to cool the magnets.
According to a second aspect of the present invention, there is provided a rotor structure, wherein an exposing portion for exposing part of the peripheral surface of the magnet is formed in the holding member to conta
Asao Yoshihito
Higashino Kyoko
Oohashi Atsushi
Tsuruhara Kenji
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