Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-04-10
2004-03-16
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S207000, C310S201000, C310S180000
Reexamination Certificate
active
06707211
ABSTRACT:
This application is based on Application No. 2001-217868, filed in Japan on Jul. 18, 2001, the contents of which are hereby incorporated by reference.
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 particularly relates to a stator winding construction of the stator for an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck, and to a method for the manufacture thereof.
2. Description of the Related Art
In recent years, compactness and high output have come to be in increasing demand in automotive alternators.
In order to achieve compactness and high output in automotive alternators, improvements in the space factor of electrical conductors housed inside a magnetic circuit of a stator, and alignment in rows and increases in density of crossover portions of a stator winding (the crossover portions outside a stator core being called coil ends) are required.
In view of these conditions, a construction has been proposed in WO 98/54823, for example, attempting to improve the space factor of the electrical conductors and to achieve alignment in rows and increases in the density of the coil ends by using short conductor segments for the electrical conductors of the stator winding.
In WO 98/54823, a stator is disclosed in which a stator winding is installed by inserting a plurality of U-shaped conductor segments having a rectangular cross-sectional shape from a first end of a stator core, then joining together end portions at the opposite end from the insertion end. Because conductor segments having a rectangular cross-sectional shape are used in this stator, the conductor segments can be housed inside the slots without gaps, enabling improvements in space factor. The stator is characterized in that a stator winding in which the coil ends are disposed regularly is formed more easily than in general conventional stators constructed by winding continuous conductor wires into an annular shape to form annular winding units, forming the annular winding units into a star shape to prepare star-shaped winding units, and installing the star-shaped winding units in the stator core. In other words, alignment in rows and increased density in the coil ends of the stator winding is achieved.
However, in the stator described in WO 98/54823, the conductor segments are prepared by bending short conductor wires having a rectangular cross-sectional shape at a central portion thereof to form the U shape. In this bending process, large stresses arises in the bent portion of the rectangular conductor wires, damaging the electrically-insulating coating covering the conductor segments and causing electrical insulation to deteriorate.
Thus, it has been proposed in Japanese Patent Non-Examined Laid-Open No. 2000-299949, for example, that a central portion only of short conductor wires having a rectangular cross-sectional shape is formed into circular cross-sectional shape, to reduce the stresses arising in the bent portion during bending in an attempt to suppress damage to the electrically-insulating coating.
FIG. 26
is a cross section showing part of a conventional stator for an automotive alternator described in Japanese Patent Non-Examined Laid-Open No. 2000-299949, for example, and
FIG. 27
is a perspective showing conductor segments constituting a stator winding of the stator in FIG.
26
.
In
FIG. 26
, a stator winding installed in slots
2
a
of a stator core
2
is constituted by a plurality of electrical conductors, four electrical conductors being housed in each of the slots
2
a
and an insulator
3
being disposed so as to surround the four electrical conductors. The four electrical conductors in each of the slots
2
a
are arranged in a single row inside the slot in order of Address
1
, Address
2
, Address
3
, and Address
4
from a radially-inner side.
An electrical conductor
4
a
in Address
1
of a first slot
2
a
forms a pair with an electrical conductor
4
b
in Address
4
in a second slot
2
a
a pitch of one pole away in a clockwise direction around the stator core
2
. Similarly, an electrical conductor
5
a
in Address
2
of the first slot
2
a
forms a pair with an electrical conductor
5
b
in Address
3
in the second slot
2
a
a pitch of one pole away in a clockwise direction around the stator core
2
. The electrical conductors
4
a,
4
b,
5
a
and
5
b
forming these pairs are connected by passing through return portions
4
c
and
5
c
described below using continuous wires at a first axial end of the stator core
2
.
Consequently, at the first end of the stator core
2
, the continuous wire connecting the electrical conductor
4
b
in Address
4
and the electrical conductor
4
a
in Address
1
surrounds the continuous wire connecting the electrical conductor
5
b
in Address
3
and the electrical conductor
5
a
in Address
2
. In other words, at the first end of the stator core
2
, the return portion
5
c
is surrounded by the return portion
4
c.
Hence, at the first end of the stator core
2
, a first coil end group is constructed by arranging the return portions
4
c
and
5
c
in a circumferential direction to form two layers in an axial direction.
On the other hand, the electrical conductor
5
a
in Address
2
of the first slot
2
a
forms a pair with the electrical conductor
4
a
in Address
1
in the second slot
2
a
a pitch of one pole away in a clockwise direction around the stator core
2
. Similarly, the electrical conductor
4
b
in Address
4
of the first slot
2
a
forms a pair with the electrical conductor
5
b
in Address
3
in the second slot
2
a
a pitch of one pole away in a clockwise direction around the stator core
2
. The electrical conductors
4
a,
4
b,
5
a
and
5
b
forming these pairs are connected by joining at a second axial end of the stator core
2
.
Consequently, at the second end of the stator core
2
, outer joint portions connecting the electrical conductor
4
b
in Address
4
and the electrical conductor
5
b
in Address
3
, and inner joint portions connecting the electrical conductor
4
a
in Address
1
and the electrical conductor
5
a
in Address
2
are arranged in a mutually offset state in a radial direction and circumferential direction. Hence, at the second end of the stator core
2
, a second coil end group is constructed by arranging the outer joint portions and the inner joint portions in two rows in a circumferential direction so as to form a single row in a radial direction.
As shown in
FIG. 27
, the electrical conductor
4
a
in Address
1
and the electrical conductor
4
b
in Address
4
are furnished by a large segment
4
in which a short conductor wire is formed into a U shape, and the electrical conductor
5
a
in Address
2
and the electrical conductor
5
b
in Address
3
are furnished by a small segment
5
in which a short conductor wire is formed into a U shape. Each of the segments
4
and
5
are provided with portions which extend in an axial direction so as to be housed inside the slots
2
a,
and are also provided with inclined portions
4
f,
4
g,
5
f,
and
5
g
extending so as to be inclined at a predetermined angle relative to the axial direction and return portions
4
c
and
5
c
connecting the inclined portions
4
f,
4
g,
5
f,
and
5
g
. First coil ends extending outward at the first axial end surface of the stator core
2
are formed by the inclined portions
4
f,
4
g,
5
f,
and
5
g
and the return portions
4
c
and
5
c.
At the second end of the stator core
2
, the projecting ends of the large segments
4
are bent away from each other, and the projecting ends of the small segments
5
are bent toward each other. The inner joint portions are formed by joining together large-segment end portions
4
d
and small-segment end portions
5
d
by welding, and the outer joint portions are formed by joining together large-segment end portions
4
e
and small-segment end portions
5
e
by welding. Hence, second coil end
Adachi Katsumi
Asao Yoshihito
Harada Yoshihiro
Kanai Hirotatsu
Kuroki Kensaku
Aguirrechea J.
Dougherty Thomas M.
Mitsubishi Denki & Kabushiki Kaisha
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