Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-05-18
2001-08-28
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S208000, C029S596000, C029S606000
Reexamination Certificate
active
06281612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Filed of the Invention
The present invention relates to a stator of the AC generator adapted for use in a vehicle and a method of manufacturing the same and, in particular, to a stator of the AC generator adapted for use in a vehicle and a method of manufacturing the same which serve to enhance rigidity by increasing the space factor of a stator coil which is housed within the slot portion.
2. Description of the Related Art
FIG. 13
is a cross-sectional view illustrating the arrangement of a conventional AC generator adapted for use in a vehicle.
In the conventional AC generator adapted for use in a vehicle, a Lundell type rotor
7
is rotatably fitted into a case
3
comprising a front bracket
1
and a rear bracket
2
each made of aluminum by way of a shaft
6
, while a stator
8
is fixedly fitted to the surface of the inner wall of the case
3
in such a way that the stator
8
covers the outer periphery of the rotor
7
.
A shaft
6
is rotatably supported against the front bracket
1
and the rear bracket
2
. A pulley
4
is fixedly fitted to one end of this shaft
6
so that the rotational torque of the engine may be transmitted to the shaft
6
by way of a belt (not shown).
A slip ring
9
which supplies a current to the rotor
7
is rigidly fitted to the other end portion of the shaft
6
, and a pair of brushes
10
is housed within a brush holder
11
disposed within the case
3
so that it may lie in slideable contact with the slip ring
9
. A regulator
18
, which regulates the output voltage of the stator
8
, is adhered to a heat sink
17
fitted on the brush holder
11
. A rectifier
12
is electrically connected to the stator
8
to rectify the alternating current generated in the coil of the stator
8
into the direct current and is mounted within the case
3
.
The rotor
7
comprises a rotor coil
13
which generates the magnetic flux when a current flows therein, and a pair of pole cores
20
,
21
provided to cover the rotor coil
13
and be magnetic poles as a result of the magnetic flux generated by the rotor coil
13
. The pair of pole cores
20
,
21
are made of iron, and a plurality of claw-shaped magnetic poles
22
,
23
are provided on the outer circumference of the poles cores
20
,
21
so as to protrude at equiangular intervals in their circumferential direction. The pole cores
20
,
21
are fixedly fitted to the shaft
6
in an opposed relation to each other so that their claw-shaped magnetic poles
22
,
23
are able to engage with each other. Further, fans
5
are fixedly attached to both axial ends of the rotor
7
.
The stator
8
comprises a stator core
15
and a stator coil
16
achieved by winding a conductor wire around the stator core
15
, and an alternating current is generated by alternating the magnetic flux of the rotor
7
with the rotation of the rotor
7
.
In such conventional AC generator, the current is supplied to the rotor coil
13
from a battery (not shown) by way of the brush
10
and the slip ring
9
, thereby generating the magnetic flux. Owing to this magnetic flux, the claw-shaped magnetic poles
22
of one pole core
20
are magnetized to N polarities, while the claw-shaped magnetic poles
23
of the other pole core
21
are magnetized to S polarities. On the other hand, the rotational torque of the engine may be transmitted to the shaft
6
by way of the belt and the pulley
4
, causing the rotor
7
to rotate. As a result, a rotational magnetic field is imparted to the stator coil
16
, and an electromotive force may take place in the stator coil
16
. This AC electromotive force passes through the rectifier
12
to be rectified into a direct current, its voltage is regulated by the regulator
18
and the battery is electrically charged.
Here, in a common AC generator for use in a vehicle, the stator core
15
has a core back portion
15
a
, substantially rectangular tooth portions
15
b
protruding from the core back portion
15
a
in the direction of the inner circumference thereof, and notch portions
15
d
provided on the outer circumference of the core back portion
15
a
so as to oppose to the tooth portions
15
b
respectively. The tooth portions
15
b
are provided, for example,
36
at the equiangular intervals as viewed in the circumferential direction, and a slot portion
15
c
which is interleaved between adjacent tooth portions
15
b
,
15
b
may serve as a space into which the coil is inserted. The
36
tooth portions
15
b
are each opposed to 12 nailed-shaped magnetic poles
22
,
23
by way of a minor clearance as viewed in the inner direction, and the magnetic flux caused by the rotational magnetic field flows as indicated by broken line of FIG.
14
. Incidentally, in
FIG. 14
, for the sake of convenience, the claw-shaped magnetic poles
23
are not shown.
Accordingly, the major portion of each tooth portion
15
b
, which serves as a passageway for a predetermined magnetic flux to pass through has preferably a uniform cross-sectional area because the magnetic flux is not branched off and is not increased or decreased, and does not increase or decrease there. That is, in order to unify the density of the magnetic flux within the tooth portion
15
b
, the shape of each tooth portion
15
b
is preferably of rectangular form rather than of trapezoidal form. Further, the tip portion of each tooth portion
15
b
has a circumferentially extending portion so as to exclude leakage of the magnetic flux to smooth the density of the magnetic flux at the air gap.
Next, a conventional method of manufacturing the stator
8
is described with reference to
FIGS. 15 and 16
.
First, a thin steel plate member is supplied to a press processing machine (not shown) to form two-way belt-shaped members
30
each having the core back portion
30
a
and the tooth portion
30
b
from the one-way thin steel plate member, as shown in FIG.
15
. At this time, arcuate notch portions
30
c
are provided on the outer circumference of the core back portion
30
a
so as to oppose to the tooth portions
30
b
respectively. With the core back portions, tooth portions and the notch portions aligned with each other, the two-way belt-shaped members
30
are overlapped and are wound in a hollow cylindrical form. Next, the cylindrically wound belt-shaped members
30
are welded for integration, and then are subjected to insulating coating to obtain a hollow cylindrical stator core
15
, as shown in FIG.
16
. In this stator core
15
, the core back portion
30
a
, tooth portion
30
b
and notch potion
30
c
of the belt-shaped member
30
are each consecutive in the axial direction to form a core back portion
15
a
, a tooth portion
15
b
and a notch portion
15
d.
Next, the tip portion of a group of coils formed in the form of a star (not shown) is deformed to insert into each slot portion
15
c
of the stator core
15
from the side of the inner circumference thereof, while the part of the coils extending from the slot portion
15
c
is deformed in the circumferential direction to obtain the stator
8
.
Incidentally, this conventional method of manufacturing the stator is described in, for example, Japanese Unexamined Patent Publication No. 60-7898 and Japanese Patent No. 2541381.
Here, in the belt-shaped member
30
obtained by punching the thin steel plate, as shown in
FIG. 15
, the major portion of each tooth portion and each slot portion is of rectangular form. When the belt-shaped member
30
is wound in the from of a hollow cylinder, the tip end portions of the tooth portions each become close to each other in the circumferential direction with the result that each slot portion achieves a substantially trapezoidal form which spreads in the outer circumferential direction, as shown in FIG.
16
.
Further, used for the stator coil
16
is a conductor wire of circular form in cross section in view of the workability and ease of availability.
In the AC generator, in order to generate the amount of magnetic flux for electrical generation as many as possible, it is necessary to accommodate a large n
Adachi Katsumi
Asao Yoshihito
Higashino Kyoko
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tamai Karl
LandOfFree
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