Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-11-07
2002-10-08
Waks, Joseph (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S256000, C310S260000
Reexamination Certificate
active
06462453
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stator for an alternator driven by an internal combustion engine, for example, and in particular, relates to a stator construction for an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck.
2. Description of the Related Art
FIG. 20
is a cross section showing a conventional automotive alternator.
In
FIG. 20
, the automotive alternator includes: a case
3
composed of an aluminum front bracket
1
and an aluminum rear bracket
2
; a shaft
6
rotatably mounted inside the case
3
, a pulley
4
being fastened to a first end of the shaft
6
; a Lundell-type rotor
7
fastened to the shaft
6
; fans
5
fastened to first and second axial ends of the stator
78
; a stator
8
fastened to an inner wall of the case
3
50
as to cover an outer circumferential side of the rotor
7
; slip rings
9
fastened to a second end of the shaft
6
for supplying electric current to the rotor
7
; a pair of brushes
10
which slide in contact with the slip rings
9
; a brush holder
11
for holding the brushes
10
; a rectifier
12
which is electrically connected to the stator
8
to convert alternating current generated in the stator
8
into direct current; a heat sink
17
fitted onto the brush holder
11
; and a regulator
18
mounted on the heat sink
17
for adjusting the magnitude of an alternating voltage generated in the stator
8
.
The rotor
7
is composed of a rotor coil
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 coil
13
, magnetic poles being formed in the pole cores
20
and
21
by magnetic flux generated in the rotor coil
13
. The pair of pole cores
20
and
21
are made of iron, each has eight 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
are fastened to the shaft
6
facing each other such that the claw-shaped magnetic poles
22
and
23
intermesh.
The stator
8
is provided with a stator core
15
, and a stator coil
16
which generates alternating current due to changes in magnetic flux produced by the rotor coil
13
accompanying the rotation of rotor
7
wound to the stator core
15
.
In the automotive alternator constructed in this manner, electric current is supplied from a battery (not shown) through the brushes
10
and the slip rings
9
to the rotor coil
13
, generating magnetic flux. The claw-shaped magnetic poles
22
of the first pole core
20
are magnetized with north-seeking (N) poles by this magnetic flux, and the claw-shaped magnetic poles
23
of the first pole core
21
are magnetized with south-seeking (S) poles.
At the same time, rotational 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 coil
16
, generating electromotive force in the stator coil
16
. This alternating electromotive force passes through the rectifier
12
and is converted into direct current, the output is adjusted by the regulator
18
, and the battery is recharged.
When generating electricity, the rotor coil
13
, the stator coil
16
, the rectifier
12
, and the regulator
18
continuously generate heat. In an alternator having a rated output current in the 100A class, these components generate 60W, 500W, 120W, and 6W of heat, respectively at rotational points at which the temperature is high.
In order to cool this heat produced due to the generation of electricity, air intake openings
1
a
and
2
a
are disposed in axial end surfaces of the front bracket
1
and the rear bracket
2
, and air discharge openings
1
b
and
2
b
are disposed in two outer circumferential shoulder portions of the front bracket
1
and the rear bracket
2
, opposite the radial outside of the front-end and rear-end coil end groups
16
f
and
16
r
of the stator coil
16
.
At the rear end, external air is drawn in through the air intake openings
2
a
disposed opposite the heat sink of the rectifier
12
and the heat sink
17
of the regulator
18
, respectively, by rotation of fans
5
, flowing along the axis of the shaft
6
, cooling the rectifier
12
and the regulator
18
, and is then deflected centrifugally by the fans
5
, cooling the rear-end coil end group
16
r
of the stator coil
16
before being expelled to the outside through the air discharge openings
2
b
. At the same time, at the front end, external air is drawn in axially through air intake openings
1
a
by rotation of the fans
5
, and is then deflected centrifugally by the fans
5
, cooling the front-end coil end group
16
f
of the stator winding
16
before being expelled to the outside through the air discharge openings
1
b.
Next, a method of winding the stator coil
16
will be explained with reference to FIG.
22
. Moreover, for convenience, the method of winding a coil having one turn is shown in FIG.
22
.
The stator coil
16
is constructed by connecting in series a number of coil segments
30
(strands of wire) composed of a copper material, for example, which are short electrical conductors having a flat cross section coated with insulation. Each coil segment
30
is formed into a general U shape composed of a pair of straight portions
30
a
connected by a V-shaped turn portion
30
b.
The coil segments
30
are inserted from the rear end two at a time into sets of slots
15
a
three slots apart. At that time, four straight portions
30
a
are housed in each of the slots
15
a
so as to line up in one row in a radial direction. The coil segments
30
on an inner circumferential side are each inserted into a first position from the inner circumferential side (hereinafter called “the first address”) of first slots
15
a
, and inserted into a second position from the inner circumferential side (hereinafter called “the second address”) of second slots
15
a
three slots away, and the coil segments
30
on an outer circumferential side are each inserted into a third position from the inner circumferential side (hereinafter called “the third address”) of the first slots
15
a
, and inserted into a fourth position from the inner circumferential side (hereinafter called “the fourth address”) of the second slots
15
a
three slots away. In other words, the coil segments
30
are housed within the sets of slots
15
a
three slots apart so as to form different layers.
Next, the free ends
30
c
of the coil segments
30
extending outwards at the front end are bent to open outwards (circumferentially outwards) so as to be at a constant angle relative to the direction of the grooves of the slots
15
a
, and in addition, the free ends
30
c
are each bent so as to extend in the same axial direction as the stator core
15
. Then, with apex portions of the turn portions
30
b
of each of the coil segments
30
positioned so as to be at the same height, the free ends
30
c
of the coil segments
30
extending outwards at the front end from the first address within the slots
15
a
and the free ends
30
c
of the coil segments
30
extending outwards at the front end from the second address within the slots
15
a
three slots away are stacked radially and joined by welding. Thus, two inner circumferential coils are obtained by connecting in series a number of the coil segments
30
which are housed in a first slot group constituted by every third slot
15
a.
Similarly, the free ends
30
c
of the coil segments
30
extending outwards at the front end from the third address within the slots
15
a
and the free ends
30
c
of the coil segments
30
extending outwards at the front end from fourth address within the slots
15
a
three slots away are stacked radially and joined together by welding. Thus, two outer circumferential coils are obtained by connecting in series a number of the coil segments
30
which are housed in the first slot group const
Adachi Katsumi
Asao Yoshihito
Katayama Hiroki
Lam Thanh
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
Waks Joseph
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