Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-12-13
2002-12-24
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S184000, C310S208000
Reexamination Certificate
active
06498413
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck, for example, to a stator winding assembly of the automotive alternator, and to a method of manufacture for the stator winding assembly.
2. Description of the Related Art
To reduce the size and increase the output of alternators driven by internal combustion engines, it is necessary to increase the space factor of electrical conductors housed within magnetic circuits of a stator, and to line up and increase the density of crossover portions (coil end portions) of a stator winding, and various improvements have been proposed, as for example in Japanese Patent Laid-Open No. HEI 11-164506.
FIGS. 27 and 28
are perspectives from a front end and a rear end, respectively, of part of a stator winding of a conventional alternator of this type, and
FIG. 29
is a perspective showing a construction of a conductor segment used in the stator winding of the conventional alternator shown in
FIGS. 27 and 28
.
In
FIGS. 27
to
29
, a stator
90
is constituted by a stator core
91
, a stator winding
92
constituted by a number of electrical conductors disposed inside slots
91
a
formed in the stator core
91
, and insulators
93
providing electrical insulation between the stator core
91
and the electrical conductors.
In the stator core
91
of this conventional example, ninety-six slots
91
a
are disposed at even pitch so as to house two three-phase alternating current windings such that the number of slots housing each phase portion of the three-phase alternating current windings corresponds to the number of magnetic poles in a rotor. Four electrical conductors are housed within each of the slots
91
a
so as to line up in one row in a radial direction, and these electrical conductors are connected in a predetermined winding pattern to form the stator winding
92
. Here, a first position, a second position, a third position, and a fourth position in a radial direction from an inner circumferential side inside the slots
91
a
in which the electrical conductors are housed will be called a first address, a second address, a third address, and a fourth address, respectively.
Large segments
95
and small segments
96
are formed by bending short lengths of a conductor such as copper into general U shapes in which pairs of straight portions
95
a
and
96
a
are linked by turn portions
95
b
and
96
b.
The small segments
96
are inserted one at a time from a rear end into pairs of slots
91
a
six slots apart (a pitch of one magnetic pole). Similarly, the large segments
95
are inserted one at a time from the rear end into pairs of slots
91
a
six slots apart (a pitch of one magnetic pole). Then, end portions of the large segments
95
and the small segments
96
extending outwards at a front end are joined to each other to constitute the stator winding
92
.
More specifically, in pairs of slots
91
a
six slots apart, the small segments
96
are inserted from the rear end into the second address within first slots
91
a
and into the third address within second slots
91
a,
and the large segments
95
are inserted from the rear end into the first address within the first slots
91
a
and into the fourth address within the second slots
91
a.
Thus, within each of the slots
91
a,
two straight portions
95
a
of the large segments
95
and two straight portions
96
a
of the small segments
96
are disposed to line up in a row of four in a radial direction.
Then, end portions
95
c
of the large segments
95
extending outwards at the front end from the first address within the first slots
91
a
are joined to end portions
96
c
of the small segments
96
extending outwards at the front end from the second address within the second slots
91
a
six slots away in a clockwise direction from the first slots
91
a.
In addition, the end portions
95
c
of the large segments
95
extending outwards at the front end from the fourth address within the first slots
91
a
are joined to the end portions
96
c
of the small segments
96
extending outwards at the front end from the third address within the second slots
91
a
six slots away in a counter-clockwise direction from the first slots
91
a.
Thus, two winding sub-portions are formed, which are lap windings having two turns per lap. These two winding sub-portions are connected in series to form one winding phase portion having four turns.
Similarly, a total of six winding phase portions each having four turns are formed by offsetting by one slot at a time the positions of the slots into which the large segments
95
and the small segments
96
are inserted. Then, three each of these winding phase portions are connected into each of the two three-phase alternating current windings which constitute the stator winding
92
.
In the conventional stator
90
constructed in this manner, at the rear end of the stator core
91
, the turn portions
95
b
of the large segments
95
are disposed so as to cover outer circumferential sides of the turn portions
96
b
of the small segments
96
inserted into the same pairs of slots
91
a.
As a result, the turn portions
95
b
and
96
b
are disposed circumferentially to constitute a rear-end coil end group.
At the front end of the stator core
91
, on the other hand, joint portions formed by joining the end portions
95
c
of the large segments
95
extending outwards at the front end from the first address within the first slots
91
a
and the end portions
96
c
of the small segments
96
extending outwards at the front end from the second address within the second slots
91
a
six slots away, and joint portions formed by joining the end portions
95
c
of the large segments
95
extending outwards at the front end from the fourth address within the first slots
91
a
and the end portions
96
b
of the small segments
96
extending outwards at the front end from the third address within the second slots
91
a
six slots away are disposed to line up radially. As a result, joint portions formed by joining the end portions
95
c
and
96
c
to each other are disposed circumferentially in two rows in a radial direction to constitute a front-end coil end group.
Because the stator winding
92
of the conventional alternator is constructed by inserting the large segments
95
and the small segments
96
formed by bending the short lengths of conductor into general U shapes into the slots
91
a
of the stator core
91
from the rear end and joining together the end portions of the segments extending outwards at the front end as explained above, one problem has been that a large number of the large segments
95
and the small segments
96
must be inserted into the slots
91
a
of the stator core
91
and end portions thereof must be joined one by one, significantly reducing workability and decreasing mass-producibility.
In addition, in order to join the end portions
95
c
of the large segments
95
and the end portions
96
c
of the small segments
96
, it is necessary to clamp a portion of each of the end portions
95
c
and
96
c
together using a jig, and another problem has been that it is necessary to extend the segments out by an extra amount from the stator coil
91
to allow for the clamping, preventing the stator
90
from being reduced in size.
In the conventional stator
90
, because the end portions
95
c
and
96
c
are joined to each other by clamping portions thereof in a jig and welding the end portions
95
c
and
96
c
together, the height of the coil ends is increased, and the large segments
95
and the small segments
96
are softened by temperature increases during welding, thereby causing rigidity of the stator to be decreased. As a result, other problems have been that when the conventional stator
90
is mounted to an alternator, coil leakage reactance in the coil end portions is increased to cause output to deteriorate, wind resistance is increased to exacerbate wind noise, and rigidity of the sta
Asao Yoshihito
Imori Hideo
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Tran
Sughrue & Mion, PLLC
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