Alternator

Details Alternator Alternator

2000-06-23

2002-02-19

Mullins, Burton S (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S179000, C310S180000, C310S207000

Reexamination Certificate

active

06348750

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an alternator driven by an internal combustion engine, for example.
2. Description of the Related Art
FIG. 4
is a cross-section of a conventional automotive alternator. This alternator includes: a case
3
composed of an aluminum front bracket
1
and an aluminum rear bracket
2
; a shaft
6
disposed within the case
3
having a pulley
4
secured to a first end thereof; a Lundell-type rotor
7
secured to the shaft
6
; fans
5
secured to both end surfaces of the rotor
6
; a stator
8
secured to an inner wall of the case
3
; slip rings
9
secured to a second end of the shaft
6
for supplying electric current to the rotor
7
; a pair of brushes
10
sliding on the slip rings
9
; brush holders
11
accommodating the brushes
10
; a rectifier
12
in electrical contact with the stator
8
for converting alternating current generated in the stator
8
into direct current; a heat sink
17
fitted over the brush holder
11
; and a regulator
18
fastened to the heat sink
17
by adhesive for adjusting the magnitude of the 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 first and second pole cores
20
and
21
disposed so as to cover the rotor coil
13
, magnetic poles being produced in the pair of pole cores
20
and
21
by the magnetic flux. The pair of pole cores
20
and
21
are made of iron and each has eight claw-shaped magnetic poles
22
and
23
secured to the shaft so as to be spaced at even pitch circumferentially around a circumferential edge, facing each other so as to intermesh.
The stator
8
includes a stator core
15
composed of a cylindrical laminated iron core in which a number of slots extending longitudinally are formed at a predetermined pitch in a circumferential direction, and a three-phase stator winding
16
wound into the stator core
15
.
Air intake vents
1
a
and
2
a
are formed in central portions of the front bracket
1
and the rear bracket
2
, respectively, and air discharge vents
1
b
and
2
b
are formed in outer circumferential shoulder portions of the front bracket
1
and the rear bracket
2
, respectively.
Next, the wiring construction of the a-phase stator winding portion
16
a
of the three-phase stator winding
16
will be explained with reference to the winding diagram in FIG.
5
. Moreover, this diagram shows the wiring construction when the stator
8
is viewed from the rear bracket
2
end, and in the figure solid lines indicate wire at the rear bracket
2
end, and dotted lines indicate wire at the front bracket
1
end. Moreover, black dots in the circular symbols inside the slots
15
a
of the stator core
15
indicate wires extending from the front bracket
1
end to the rear bracket
2
end, and “X” symbols in the circular symbols inside the slots
15
a
of the stator core
15
indicate wires extending from the rear bracket
2
end to the front bracket
1
end.
The a-phase stator winding portion
16
a
includes first to fourth winding sub-portions
31
to
34
. The first winding sub-portion
31
, which has a first end connected to an a-phase lead wire
100
, leads from the rear bracket
2
end at the second position from an inner circumferential side (hereinafter the positions counted in order from the inner circumferential side will be called the first, second, third, and fourth positions, respectively) inside a slot
15
a
whose slot number is number
1
. Thereafter, the first winding sub-portion
31
is constructed by wave winding such that the winding alternates between the first position and the second position within the slots every third slot in a counterclockwise direction, and a second end of the first winding sub-portion
31
arrives at the first position in slot number
34
. This first winding sub-portion
31
is connected to a first end of the third winding sub-portion
33
through a first bridging portion
60
.
At the fourth position in slot number
1
, the third winding sub-portion
33
, which has a first end connected to the first bridging portion
60
from the rear bracket
2
end, is constructed by wave winding such that the winding alternates between the third position and the fourth position within the slots every third slot in a counterclockwise direction until slot number
34
, and a second end thereof arrives at the third position in slot number
34
. This third winding sub-portion
33
is connected to the second winding sub-portion
32
through a second bridging portion
61
.
At the first position in slot number
1
, the second winding sub-portion
32
, which has a first end connected to the second bridging portion
61
from the rear bracket
2
end, is constructed by wave winding such that the winding alternates between the first position and the second position within the slots every third slot in a clockwise direction until slot number
4
, and a second end thereof arrives at the second position in slot number
4
. This second winding sub-portion
32
is connected to the fourth winding sub-portion
34
through a third bridging portion
62
.
At the third position in slot number
1
, the fourth winding sub-portion
34
, which has a first end connected to the third bridging portion
62
from the rear bracket
2
end, is constructed by wave winding such that the winding alternates between the third position and the fourth position within the slots every third slot in a clockwise direction until slot number
4
, and a second end thereof arrives at the fourth position in slot number
4
. This fourth winding sub-portion
34
is connected to a neutral point lead wire
101
.
In this manner, in the a-phase stator winding portion
16
a
, the first winding sub-portion
31
, which is connected to the a-phase lead wire
100
, makes one lap in a counterclockwise direction in every third slot while alternating between the second position and the first position and then the third winding sub-portion
33
makes one lap in a counterclockwise direction in every third slot while alternating between the fourth position and the third position. In addition, the second winding sub-portion
32
makes one lap in a clockwise direction in every third slot while alternating between the second position and the first position and then the fourth winding sub-portion
34
makes one lap in a clockwise direction in every third slot while alternating between the fourth position and the third position. Each of the winding sub-portions
31
to
34
is connected in series by means of the bridging portions
60
to
62
, constituting a four-turn a-phase stator winding portion
16
a.
Similarly, a b-phase stator winding portion and a c-phase stator winding portion are formed by offsetting by one slot
15
a
and, together with the a-phase stator winding portion, constitute the star-connected three-phase stator winding
16
.
The three-phase stator winding
16
of the above construction is formed by joining a number of short conductor segments
50
such as the one shown in FIG.
6
.
The conductor segments
50
, which are component elements of the conductors, are each formed into a U shape from copper wire material having a rectangular cross section coated with insulation, and each includes a pair of first and second straight portions
51
a
and
51
b
housed inside the slots
15
a
, a base end portion
52
connecting the straight portions
51
a
and
51
b
to each other, and joining portions
53
a
and
53
b
disposed on end portions of the straight portions
51
a
and
51
b
for joining adjacent conductor segments
50
to each other.
Next, the steps in forming the a-phase stator winding portion
16
a
using the conductor segments
50
will be explained.
First, as shown in
FIG. 7
, four straight portions
51
a
and
51
b
of conductor segments
50
are arranged to line up in a row in a radial direction within each of the slots
15
a
by inserting conductor segments
50
from the rear bracket
2
end into a predetermined slot nu

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