Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-11-14
2002-06-18
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06800R, C310S184000, C322S090000
Reexamination Certificate
active
06407476
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an a.c. generator for a vehicle, and more particularly to the structure of a stator winding wound on a stator in an a.c. generator for a vehicle.
2. Description of the Related Art
FIG. 5
is a cross-sectional view showing a general a.c. generator for a vehicle.
Referring to
FIG. 5
, the a.c. generator for a vehicle is structured by rotatably mounting a Lundell-type rotor
7
inside a case
3
constructed from an aluminum front bracket
1
and an aluminum rear bracket
2
by means of a shaft
6
, and fastening a stator
8
to an inner wall of the case
3
so as to cover an outer peripheral side of the rotor
7
.
The shaft
6
is rotatably supported by the front bracket
1
and the rear bracket
2
. A pulley
4
is fastened to one end of the shaft
6
so that the rotating torque of an engine can be transmitted to a shaft
6
by means of a belt (not shown). Slip rings
9
for supplying a current to the rotor
7
are fastened to the other end portion of the shaft
6
, and a pair of brushes
10
are housed in a brush holder
11
disposed within the case
3
such that the pair of brushes
10
slide in contact with the slip rings
9
. A regulator
18
for adjusting the magnitude of an a.c. voltage generated in the stator
8
is fastened by adhesive to a heat sink
17
fitted onto the brush holder
11
. A rectifier
12
which is electrically connected to the stator
8
and rectifies the a.c. voltage generated in the stator
8
into a d.c. voltage is mounted within the case
3
.
The rotor
7
is composed of a rotor winding
13
for generating magnetic flux on passage of electric current, and a pair of pole cores
20
and
21
disposed so as to cover the rotor winding
13
, magnetic poles being formed in the pole cores
20
and
21
by magnetic flux generated in the rotor winding
13
. The pair of pole cores
20
and
21
are made of iron, each has six claw-shaped magnetic poles
22
and
23
disposed on an outer circumferential perimeter at even pitch in a circumferential direction so as to project axially, and the pole cores
20
and
21
fastened to the shaft
6
facing each other such that the claw-shaped magnetic poles
22
and
23
intermeshed. In addition, fans
5
are fastened to both ends of the rotor
7
in the axial direction thereof.
The stator
8
is composed of a cylindrical stator core
15
having a plurality of slots extending axially at a predetermined pitch in a circumferential direction, and a stator winding
16
wound on the stator core
15
.
In the a.c. generator for a vehicle thus structured, a current is supplied to the rotor winding
13
from a battery (not shown) through the brushes
10
and the slip rings
9
, to thereby generate magnetic flux. The claw-shaped magnetic poles
22
of the pole core
20
are magnetized with north-seeking (N) poles by this magnetic flux, and the claw-shaped magnetic poles
23
of the pole core
21
are magnetized with south-seeking (S) poles. At the same time, rotating torque from the engine is transmitted through the belt and the pulley
4
to the shaft
6
, rotating the rotor
7
. Thus, a rotating magnetic field is applied to the stator winding
16
, generating electromotive force in the stator winding
16
. This a.c. electromotive force passes through the rectifier
12
and is converted into a d.c. electromotive force, the magnitude of the electromotive force is adjusted by the regulator
12
and the battery is recharged.
Now, the structure of the stator winding
16
will be described with reference to FIG.
6
. In this example, the number of magnetic poles of the rotor
7
is
12
. In
FIG. 6
, reference numerals
1
to
36
denote slot Nos.
The stator core
15
is formed of a cylindrical magnetic material in which 36 slots
15
a
are formed at a predetermined pitch in a circumferential direction so as to open toward the inner peripheral side thereof.
A winding
30
is formed by wave winding a conductor
29
into every three slots
15
a
such that the order of slots into which the conductor
29
is inserted is slot number
1
,
4
,
7
, . . . ,
34
. A winding
31
is formed by wave winding a conductor
29
into every three slots
15
a
such that the order of slots into which the conductor
29
is inserted is slot number
3
,
6
,
9
, . . . ,
36
. A winding
32
is formed by wave winding a conductor
29
into every three slots
15
a
such that the order of slots into which the conductor
29
is inserted is slot number
5
,
8
,
11
, . . . ,
2
.
Those three windings
30
,
31
and
32
thus formed is connected their winding end portions
30
b,
31
b
and
32
b
together, that is, is connected into Y connection to structure the stator winding
16
. The connecting portion of the winding end portions
30
b,
31
b
and
32
b
becomes a neutral point of the stator winding
16
, and winding start portions
30
a,
31
a
and
32
a
become lead wires of the stator winding
16
. Those three windings
30
,
31
and
32
are different in electrical angle by 120° phase.
The rectifier
12
is structured in such a manner that a plus side diode d
11
and a minus side diode d
21
which are connected in series, a plus side diode d
12
and a minus side diode d
22
which are connected in series, a plus side diode d
13
and a minus side diode d
23
which are connected in series, and a plus side diode d
14
and a minus side diode d
24
which are connected in series are connected in parallel between an output terminal B and the ground. Also, as shown in
FIG. 7
, the stator winding
16
is connected to the rectifier
12
in such a manner that the winding start portion
30
a
of the winding
30
is connected between the plus side diode d
11
and the minus side diode d
21
which are connected in series, the winding start portion
31
a
of the winding
31
is connected between the plus side diode d
12
and the minus side diode d
22
which are connected in series, the winding start portion
32
a
of the winding
32
is connected between the plus side diode d
13
and the minus side diode d
23
which are connected in series, and the neutral point is connected between the plus side diode d
14
and the minus side diode d
24
which are connected in series, respectively.
In the a.c. generator for a vehicle thus structured, if the rotating speed is low, a voltage of 3
½
times of a single-phase induced voltage is developed between the wires. Also, if the rotating speed is high, although main magnetic flux is weakened by a three-phase a.c. current that flows in three single-phase windings
30
,
31
and
32
, since a tertiary higher harmonic electromotive force remains, this generator is employed with the diode connected to the neutral point.
In the conventional a.c. generator for a vehicle, since the stator winding
16
is structured by connecting the three single-phase windings
30
,
31
and
32
different in electrical angle by 120° phase into Y connection, only the voltage of 3
½
times of the single-phase induced voltage is developed between the wires, resulting in such a problem that the conventional a.c. generator could not satisfy a demand for generation when the rotating speed is low.
In order to solve the above drawback, there is proposed that the number of turns of the windings
30
,
31
and
32
in the respective phases is increased. However, in this case, there arises such a problem that a generation current decreases when the rotating speed is high.
SUMMARY OP THE INVENTION
The present invention has been made in order to solve the above problems with the conventional generators, and therefore an object of the present invention is to provide an a.c. generator for a vehicle with an improved stator winding which is capable of making a voltage developed between the wires large and making a generation current at a higher rotating speed large.
In order to achieve one aspect of the above object, according to one aspect of the present invention, there is provided an a.c. generator for a vehicle, including:
a rotor rotatably supported within a case; and
Mitsubishi Denki & Kabushiki Kaisha
Mohandesi Iraj
Ramirez Nestor
Sughrue & Mion, PLLC
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