Stator for an alternator

Details Stator for an alternator Stator for an alternator

2000-08-15

2002-04-16

Nguyen, Tran (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S184000

Reexamination Certificate

active

06373163

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. 22
is a side elevation showing part of a stator of a conventional automotive alternator such as described in Japanese Patent No. 2927288, for example,
FIG. 23
is a perspective showing a conductor segment used in the stator of the conventional automotive alternator shown in
FIG. 22
, and
FIGS. 24 and 25
are perspectives from a front end and a rear end, respectively, of part of the stator of the conventional automotive alternator shown in FIG.
22
.
In
FIGS. 22
to
25
, the stator
50
includes: a stator core
51
; a stator winding
52
wound onto the stator core
51
; and insulators
53
mounted inside slots
51
a,
the insulators
53
insulating the stator winding
52
from the stator core
51
. The stator core
51
is a cylindrical laminated core laminated by stacking thin steel plates, and has a number of slots
51
a
extending axially disposed at even pitch circumferentially so as to be open on an inner circumferential side. In this case, ninety-six slots
51
a
are formed so as to house two three-phase winding portions such that the number of slots housing each winding phase portion corresponds to the number of magnetic poles (sixteen) in a rotor (not shown). The stator winding
52
is constructed by joining a number of short conductor segments
54
in a predetermined winding pattern.
The conductor segments
54
are formed into a general U shape from an insulated copper wire material having a rectangular cross section, and are inserted two at a time from an axial rear end into pairs of slots
51
a
six slots apart (a pitch of one magnetic pole). Then, end portions of the conductor segments
54
extending outwards at a front end are joined to each other to constitute the stator winding
52
.
More specifically, in pairs of slots
15
a
six slots apart, first conductor segments
54
are inserted from the rear end into first positions from an outer circumferential side within first slots
51
a
and into second positions from the outer circumferential side within second slots
51
a,
and second conductor segments
54
are inserted from the rear end into third positions from the outer circumferential side within the first slots
51
a
and into fourth positions from the outer circumferential side within the second slots
51
a.
Thus, within each slot
15
a,
four straight portions
54
a
of the conductor segments
54
are arranged to line up in a row in a radial direction.
Then, end portions
54
b
of the conductor segments
54
extending outwards at the front end from the first positions from the outer circumferential side within the first slots
51
a
and end portions
54
b
of the conductor segments
54
extending outwards at the front end from the second positions from the outer circumferential side within the second slots
51
a
six slots away in a clockwise direction from the first slots
51
a
are joined to form an outer layer winding having two turns. In addition, end portions
54
b
of the conductor segments
54
extending outwards at the front end from the third positions from the outer circumferential side within the first slots
51
a
and end portions
54
b
of the conductor segments
54
extending outwards at the front end from the fourth positions from the outer circumferential side within the second slots
51
a
six slots away in a clockwise direction from the first slots
51
a
are joined to form an inner layer winding having two turns.
In addition, the inner-layer winding and outer-layer winding constituted by the conductor segments
54
inserted into the pairs of slots
51
a
six slots apart are connected in series to form one winding phase portion having four turns.
A total of six winding phase portions each having four turns are formed in this manner such that slots into which the conductor segments
54
are inserted are offset by one slot each. A stator winding composed of two three-phase alternating-current windings is constructed by connecting the winding phase portions three apiece into alternating-current connections.
In the conventional stator
50
constructed in this manner, at the rear end of the stator core
51
, turn portions
54
c
of pairs of conductor segments
54
inserted into the same pairs of slots
15
a
are lined up in rows in a radial direction. As a result, the turn portions
54
c
are arranged in two rows circumferentially to constitute a rear-end coil end group.
At the front end of the stator core
51
, on the other hand, joint portions formed by joining the end portions
54
b
of the conductor segments
54
extending outwards at the front end from the first positions from the outer circumferential side within the first slots
51
a
and the end portions
54
b
of the conductor segments
54
extending outwards at the front end from the second positions from the outer circumferential side within the second slots
51
a
six slots away from the first slots
51
a,
and joint portions formed by joining the end portions
54
b
of the conductor segments
54
extending outwards at the front end from the third positions from the outer circumferential side within the first slots
51
a
and the end portions
54
b
of the conductor segments
54
extending outwards at the front end from the fourth positions from the outer circumferential side within the second slots
51
a
six slots away from the first slots
51
a
are arranged to line up radially. As a result, joint portions formed by joining end portions
54
b
to each other are arranged in two rows circumferentially to constitute a front-end coil end group.
In the stator
50
of the conventional automotive alternator, as explained above, the stator winding
52
is constructed by inserting short conductor segments
54
formed in the general U shape into the slots
51
a
of the stator core
51
from the rear end, and joining end portions
54
b
of the conductor segments
54
extending outwards at the front end.
Thus, because the front-end coil end group is constructed by circumferentially arranging the joint portions formed by joining the end portions
54
b,
which have lost their insulation due to soldering or welding, the coil-end construction is easily corroded by exposure to moisture, making corrosion resistance extremely low.
Furthermore, because the front-end coil end group is composed of two rows of ninety-six joint portions, i.e., 192 joint portions, the construction facilitates short-circuiting between the joint portions, increasing the likelihood of short-circuiting accidents.
A large number of the short conductor segments
54
must be inserted into the stator core
51
and their end portions
54
b
must be joined by welding, soldering, etc., significantly reducing operability. Furthermore, the amount of each conductor segment
54
which is inserted into the slots
51
a
must be greater than the length of the stator core
51
, facilitating damage to the insulation and reducing the quality of the finished product. In addition, when joining the end portions
54
b,
short-circuiting often occurs between the joint portions due to spilt solder or weld melt, significantly decreasing mass-producibility.
In the conventional stator
50
, the end portions
54
b
of the conductor segments
54
are joined to each other by clamping a portion thereof in a jig, and soldering or welding the tips thereof. Thus, because clamping area is required for the jig and expansion of the soldered portions or welded portions occurs, the height of the coil ends is increased and space between the joint portions is reduced. Furthermore, when the end portions
54
b
of the conductor segments
54
are welded, the conductor segments
54
are softened by temperature increases during welding, leading to decreases in the rigidity of the stator. As a result, when the co

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