Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-10-18
2001-05-01
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S261100
Reexamination Certificate
active
06225727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotor for a dynamo-electric machine including magnetic bodies disposed between adjacent claw-shaped magnetic poles for minimizing magnetic flux leakage between the claw-shaped magnetic poles, and to a method for magnetizing the magnetic bodies.
2. Description of the Related Art
FIG. 9
is a cross-section of a conventional automotive alternator,
FIG. 10
is a perspective of the rotor in
FIG. 9
, and
FIG. 11
is an exploded view of the rotor in FIG.
10
. This automotive alternator includes: a case
3
comprising an aluminum front bracket
1
and an aluminum rear bracket
2
; a shaft
6
disposed in the case
3
to one end of which a pulley
4
is secured; a Lundell-type rotor
7
secured to the shaft
6
; fans
5
secured to both ends of the rotor
7
; a stator
8
secured to the inner wall of the case
3
; slip rings
9
secured to the other end of the shaft
6
for supplying electric current to the rotor
7
; a pair of brushes
10
moving in contact with the slip rings
9
; a brush holder
11
accommodating the brushes
10
; a rectifier
12
in electrical contact with the stator
8
for converting an alternating current generated in the stator
8
to a direct current; a heat sink
17
fitted over the brush holder
11
; and a regulator
18
attached to the heat sink with adhesive for adjusting the magnitude of the alternating current generated in the stator
8
.
The rotor
7
includes: a rotor coil
13
having wire
31
wound onto a bobbin
30
for generating magnetic flux by passing an electric current through the wire
31
; and a pole core
14
disposed so as to cover the rotor coil
13
in which magnetic poles are produced by the magnetic flux generated by the rotor coil
13
. The pole core
14
includes a first pole core body
21
and a second pole core body
22
which mutually intermesh. The first pole core body
21
is formed with a plurality of first claw-shaped magnetic poles
23
evenly spaced around a circumferential portion thereof. Like the first pole core body
21
, the second pole core body
22
is made of iron and is formed with a plurality of second claw-shaped magnetic poles
24
evenly spaced around a circumferential portion thereof. A magnetic body
33
magnetized in directions which reduce magnetic flux leakage between the claw-shaped magnetic poles
23
,
24
is inserted between the mutually intermeshing first claw-shaped magnetic poles
23
and second claw-shaped magnetic poles
24
. The magnetic body
33
is shaped so as to wind in a zigzag circumferentially, and is composed of plastic magnets.
The stator
8
includes: a stator core
15
; and a stator coil
16
composed of wire wound into the stator core
15
in which an alternating current is generated by changes in the magnetic flux arising in the rotor coil
13
as the rotor
7
rotates.
In an automotive alternator of the above construction, a current is supplied from a battery (not shown) via the brushes
10
and the slip rings
9
to the rotor coil
13
, generating magnetic flux, and the first claw-shaped magnetic poles
23
in the first pole core body
21
are magnetized with a north-seeking (N.) pole, and the second claw-shaped magnetic poles
24
in the second pole core body
22
are magnetized with a south-seeking (S.) pole. At the same time, because the pulley
4
is driven by the engine and the rotor
7
is rotated by the shaft
6
, a rotating magnetic field is imparted to the stator coil
16
and electromotive force arises in the stator coil
16
. This alternating-current electromotive force is converted to a direct current by means of the rectifier
12
, its magnitude is regulated by the regulator
18
, and the battery is recharged.
In a conventional rotor
7
for an automotive alternator, because centrifugal force acts on the first and second claw-shaped magnetic poles
23
,
24
as the rotor
7
rotates making the first and second claw-shaped magnetic poles
23
,
24
vibrate in the direction of arrow A in
FIG. 12
, one problem has been that there is a risk that the magnetic body
33
will be damaged in places where the tips of the claw-shaped magnetic poles collide therewith, and damage actually occurs when the rotational frequency of the rotor
7
is approximately 10000 to 15000 rpm, for example.
In order to prevent such damage to the magnetic body
33
, the magnetic body can be secured to the first pole core body
21
and the second pole core body
22
with adhesive, but even then, one problem has been that the magnetic body
33
is simultaneously subjected to loads of different magnitude and direction from each of the claw-shaped magnetic poles
23
,
24
during rotation of the rotor
7
and there is still a risk that the magnetic body
33
will be damaged.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problems and an object of the present invention is to provide a rotor for a dynamo-electric machine in which damage to the magnetic body is less likely even during high-speed rotation, improving tolerance to high speed.
Furthermore, another object of the present invention is to provide a method for magnetizing the magnetic body so that the magnetic body is magnetized to a high residual flux density.
To this end, according to the present invention, there is provided a rotor for a dynamo-electric machine comprising: a rotor coil comprising wire wound onto a bobbin for generating magnetic flux by passing an electric current through the wire; a first pole core body disposed so as to cover the rotor coil formed with a plurality of first claw-shaped magnetic poles evenly spaced around a circumferential portion thereof being magnetized by the magnetic flux; a second pole core body disposed facing the first pole core body having second claw-shaped magnetic poles spaced so as to intermesh between the first claw-shaped magnetic poles; a first magnetic body secured to the first pole core body being magnetized in directions reducing magnetic flux leakage with the second claw-shaped magnetic poles at each side surface of the first claw-shaped magnetic poles; and a second magnetic body secured to the second pole core body facing the first magnetic body across an air gap being magnetized in directions reducing magnetic flux leakage with the first claw-shaped magnetic poles at each side surface of the second claw-shaped magnetic poles.
According to another aspect of the present invention, there is provided a method for magnetizing magnetic bodies of a rotor for a dynamo-electric machine wherein a magnetically permeable member is inserted into the air gap between the first magnetic body and the second magnetic body when the first magnetic body and the second magnetic body are magnetized by passing a current through a magnetizing yoke.
REFERENCES:
patent: 5221503 (1993-06-01), Ward et al.
patent: 5539265 (1996-07-01), Harris et al.
patent: 5783895 (1998-07-01), Hakala et al.
patent: 5903084 (1999-05-01), Asao et al.
patent: 5925964 (1999-07-01), Kusase et al.
patent: 6013967 (2000-01-01), Ragaly et al.
patent: 6013968 (2000-01-01), Lechner et al.
patent: 7-298585 (1995-11-01), None
Asao Yoshihito
Oohashi Atsushi
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Tran
Sughrue Mion Zinn Macpeak & Seas, PLLC
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