Alternator

Details Alternator Alternator

2000-09-13

2003-01-07

Mullins, Burton S. (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S179000, C310S180000, C310S184000, C310S201000

Reexamination Certificate

active

06504283

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, 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. 18
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. 19
is a perspective showing a conductor segment used in the stator of the conventional automotive alternator shown in
FIG. 18
, and
FIGS. 20 and 21
are perspectives from a front end and a rear end, respectively, of part of the stator of the conventional automotive alternator shown in FIG.
18
.
In
FIGS. 18
to
21
, the stator
50
includes: a stator core
51
; a stator coil
52
wound into the stator core
51
; and insulators
53
mounted inside slots
51
a
, the insulators
53
insulating the stator coil
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. The stator coil
52
is constructed by joining a number of short conductor segments
54
in two three-phase coils. In this case, ninety-six slots
51
a
are formed so as to house two three-phase coils such that the number of slots housing each phase of the winding portions corresponds to the number of magnetic poles (sixteen) in a rotor (not shown). The two three-phase coils have a mutual phase difference of 30° (electrical angle).
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 coil
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 coil phase having four turns.
A total of six coil phases each having four turns are formed in this manner. The two three-phase coils constituting the stator coil
52
are formed by connecting three coil phases each 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 the 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, 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 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 coil
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. 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.
Now, the coil end leakage reactance due to leakage of the magnetic flux passing through the coil ends is proportionate to the height of the coil ends. In the conventional stator coil
52
, because clamping area is required for the jig, making the coil ends high, there has been a problem of increased coil end leakage reactance, causing output to deteriorate.
Furthermore, if the number of claw-shaped magnetic poles and the number of slots are increased, the coils in the coil ends are closer together, and when the joining portions of the conductor segments expand, because the space between the coils in the coil ends become excessively narrow and the height of the coil ends is increased, there is mutual interference between the coils in the coil ends, and there has been a problem of deterioration in output.
Furthermore, in the conventional stator
50
, 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., which has led to a problem of significantly decreased operability. In addition, when joining the end portions
54
b
, there has also been a problem of short circuiting often occurring between the joint portions due to spilt solder or weld melt, significantly decreasing mass-productivity.
Furthermore, in the conventional stator construction which uses conductor segments
54
, because buckling, etc., occurs more frequently during insertion of the conductor segments
54
into the slots as the number of slots increases, it has been difficult to apply this construction to an alternator aiming for compactness and high output by increasing the number of claw-shaped magnetic poles and the number of slots.
Furthermore, there has been a problem of decreased reliability of the conventional stator
50
constructed in this manner becaus

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