Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-06-13
2003-01-14
Nguyen, Tran (Department: 3102)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S184000
Reexamination Certificate
active
06507137
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a vehicular AC generator adapted to prevent cooling ability from being deteriorated by crossover connection portions of each of turns of phase windings of a stator coil. More particularly, this invention relates to a coil winding structure for decreasing or omitting crossover connection portions of each of turns of phase windings of a stator coil.
2. Description of the Related Art
FIG. 8
is sectional diagram showing the configuration of a conventional vehicular AC generator.
The conventional vehicular AC generator is configured so that a Lundell-type rotor
7
is rotatably mounted within a case
3
consisting of an aluminum front bracket
1
and an aluminum rear bracket
2
by means of a shaft
6
, and that a stator
8
is fixed to the inner wall of the case
3
in such a manner as to cover the outer periphery of the rotor
7
.
The shaft
6
is rotatably supported by the front bracket
1
and the rear bracket
2
. A pulley
4
is fixed to one end of this shaft
6
, so that the rotating torque of an engine can be transmitted to the shaft
6
by means of a belt (not shown).
Slip rings
9
for supplying electric current to the rotor
7
are fixed to the other end of the shaft
6
. A pair of brushes
10
are accommodated in a brush holder
11
, which is disposed in the case
3
, in such a way as to slide in contact with the slip rings
9
. A regulator
19
for regulating the output voltage of the stator
8
is attached to a heat sink
17
fitted on the brush holder
11
. A rectifier
12
electrically connected to the stator
8
and adapted to rectify an alternating current generated in the coil the stator
8
to a direct current is mounted within the case
3
.
The rotor
7
comprises a rotor coil
13
which generates magnetic flux when an electric current flows therein, and a pair of pole cores
20
and
21
disposed so as to cover the rotor coil
13
in which magnetic poles are formed by the magnetic flux generated by the rotor coil
13
. The pole cores
20
and
21
are made of iron, each has a plurality of claw-like magnetic pole pieces
22
and
23
circumferentially provided along the outer circumferential edge thereof at an equiangular pitch in such a way as to protrude therefrom. The pole cores
20
and
21
are fixed to the shaft
6
in such a manner as to face each other so that the magnetic pole pieces
22
and
23
engage with each other. Moreover, fans
5
are fixed to both axial ends of the rotor
7
.
The stator
8
comprises a stator core
15
and a stator coil
16
composed of wires wound around this stator core
15
in which an alternating current is generated by alternating the magnetic flux of the rotor
7
owing to the rotation of the rotor
7
.
In the conventional AC generator configured in this manner, an electric current is supplied from a battery (not shown) to the rotor coil
13
by means of the brushes
10
and the slip rings
9
, so that the magnetic flux is generated. The claw-like magnetic poles
22
of the pole core
20
are magnetized to N polarities by this magnetic flux. The claw-like magnetic poles
23
of the pole core
21
are magnetized to S polarities by this magnetic flux. On the other hand, the rotatinal torque of the engine is transmitted to the shaft
6
by means of the belt and the pulley
4
, so that the rotor
7
is rotated. Thus, a rotating magnetic field is given to the stator coil
16
. Then, an electromotive force is generated in the stator coil
16
. This AC electromotive force is transmitted to and rectified by the rectifier
12
to a direct current, its voltage is regulated by the regulator
18
. Then, the battery is recharged.
The rotor coil
13
, the stator coil
16
, the rectifier
12
and the regulator
18
emit heat at all times during power generation. The heating values of these elements are 60W, 50W, 120W and 6W, respectively, at a high-temperature rotation point in the case of an AC generator of the class that has a rated output current of 100 A.
Thus, intake openings
1
a
and
2
a
and exhaust openings
1
b
and
2
b
are provided in the front bracket
1
and the rear bracket
2
so as to cool heat generated by power generation. As indicated by arrows in
FIG. 8
, at the rear side of the generator, outside air is sucked by the rotation of the fans
5
from the intake openings
2
a
respectively provided in such a way as to face a heat sink
19
of the rectifier
12
and the heat sink
17
of the regulator
18
and flows along the axis of the shaft
6
. Consequently, the air cools the rectifier
12
and the regulator
18
. Thereafter, each of the flows of the air is turned by the corresponding fan
5
to a centrifugal direction. Thus, the air cools the rear-side coil end of the stator coil
16
. Then, the air is discharged to the outside through the exhaust openings
2
b.
On the other hand, at the front side of the generator, outside air is sucked by the rotation of the fans
5
from the intake openings
1
a
in the axial direction. Thereafter, each of the flows of the air is turned by the corresponding fan
5
to a centrifugal direction. Thus, the air cools the front-side coil end of the stator coil
16
. Then, the air is discharged to the outside through the exhaust openings
1
b.
Next, the structure of the conventional stator
8
will be concretely described hereinbelow with reference to
FIGS. 9
to
13
.
FIG. 9
is a rear elevation illustrating the coil connection employed in the conventional stator.
FIG. 10
is a perspective view of a primary part of the conventional stator, viewed from the rear side thereof.
FIG. 11
is a perspective view of the primary part of the conventional stator, viewed from the front side thereof.
FIGS. 12 and 13
are schematic diagrams illustrating a method of winding the conventional stator coils.
The stator core
15
is formed like a cylinder and has a plurality of teeth
15
a
(each having a rectangular section) provided along the circumference thereof at an equiangular pitch in such a manner as to inwardly radially project therefrom. A slot
15
b
for accommodating the coil therein is formed between each pair of adjacent teeth
15
a.
Each of the slots
15
b
extends in parallel with the axial direction and is opened to the inner circumference of the stator core
15
. In the case of this conventional generator, the rotor
7
has 12 magnetic pole pieces, and the stator
8
has 36 slots
15
b.
Thus, the number of slots per magnetic pole and per phase is 1.
Each of the stator coils
16
is constituted by (nearly U-shaped) coil pieces
30
as follows. Each of the coil pieces
30
has a pair of leg portions
30
a
connected by a nearly V-shaped connecting portion
30
b.
The leg portions
30
a
of each of the coil pieces
30
are inserted into two slots
15
b,
whose slot numbers are different from each other by three, from the rear side of the stator core
15
. Then, open-end portions
30
c
extending toward the front side of the stator core
15
are joined together. Thus, the stator coils
16
are constructed. Incidentally, a coil conductor is constructed by connecting and integrating the coil pieces
30
.
Two coil pieces
30
are inserted into each set of the two slots
15
b,
whose slot numbers are by 3, from the rear side of the stator core
15
, as shown in FIG.
12
. At that time, 4 leg portions
30
a
are accommodated in each of the slots
15
b
in such a manner as to be radially arranged in a line, as illustrated in FIG.
9
. Further, the leg portions
30
a
of the outer-circumference-side coil piece
30
are inserted into a first place, which is closest to the outer circumference, in one of the slots
15
b,
whose slot numbers differ from each other by 3, and into the second place closest to the outer circumference, in the other slot
15
b.
On the other hand, the leg portions
30
a
of the inner-circumference-side coil piece
30
are inserted into a third place, which is the third closest place to the outer circumference, in one of the slots
15
b,
whose slot numbers differ from each other b
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