Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-08-17
2004-08-10
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S233000, C310S206000, C310S207000, C310S071000
Reexamination Certificate
active
06774525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a dynamo-electric machine having a commutator that includes a plurality of segments.
2. Description of the Related Art
FIG. 11
is a side sectional diagram of a motor
100
for use in an electric power steering system, which is a conventional dynamo-electric machine. This motor
100
for an electric power steering system comprises a cylindrical yoke
101
, magnetic poles
102
constituted by permanent magnets, the number of which is 4, and fixed in this yoke
101
, a shaft
104
provided in the yoke
101
in such a manner as to be enabled by a bearing
103
to freely rotate, an armature
105
fixed to this shaft
104
, a commutator
106
fixed to an end portion of the shaft
104
, and brushes
108
made by elastic forces of springs (not shown) to abut against the surface of this commutator
106
and held by brush holders
107
.
The armature
105
comprises a core
109
having twenty-two slots, which axially extend, and a winding
111
constituted by a conductor lap-wound through the slots
110
.
The hollow-cylinder-like commutator
106
has twenty-two copper segments
112
disposed at equal intervals, and resin materials, placed between adjacent segments
112
, for holding and insulating the adjacent segments
112
from each other.
In the four-pole lap-wound motor
100
for use in the electric power steering system, electric current is externally supplied to the wiring
111
through the brushes
108
that abut against the segments
112
. Consequently, the armature
105
rotates together with the shaft
104
by electromagnetic action.
FIGS. 12 and 13
are developed plan winding diagrams each illustrating the cylindrical arrangement of the winding
111
, the magnetic poles
102
, the commutator
106
, and the brushes
108
in the direction of rotation so as to explain the positional relation among the mounting positions of these members.
As shown in
FIG. 11
, the motor
100
for use in an electric power steering system has twenty-two teeth
113
, twenty-two segments
112
, and four magnetic poles
102
. For easy understanding of the connection relation between the coil portions
114
and the segments
112
, this figure shows such an arrangement throughout a range longer than an actual range, that is, a range of more 360 degrees (720 degrees in this case) in terms of a mechanical angle.
Portions designated by characters “N” and “S” are the magnetic poles
102
. Further, parts, each of which is designated by one of symbols “+” and “−” described at the bottom thereof, are the brushes
108
. Rectangles, to which the numbers
1
to
22
described under the characters “N” and “S” are respectively assigned, are the teeth
113
for defining the slots
110
. Further, rectangles described just above the brushes
108
, to which the numbers
1
to
22
are respectively assigned, are the segments
112
.
As illustrated in
FIG. 14
, each of the windings
111
of this example is constituted by what is called “double winding”, in which the two coil portions
114
are parallel-connected between each pair of adjacent ones of the segments
112
.
FIG. 12
is a winding diagram illustrating the outer (or upper) winding
111
provided in the radial direction of the core
109
of the armature
105
, between the windings.
FIG. 13
is a winding diagram illustrating the inner (or lower) winding
111
provided in the radial direction of the core
109
of the armature
105
, between the windings.
The windings
111
constituted by the “double winding” has advantages over what is called “single winding” in that thinner conductors can be used, and that thus the workability in winding is enhanced.
Incidentally, in the case of each of the coil portions
114
indicated by dotted lines in
FIG. 14
, each of the brushes
108
is brought into abutting engagement with two of the segment
112
, as shown in FIG.
15
. Thus, these segments are at equal electric potential. Consequently, the dotted lines indicate that no current flows through the corresponding wiring portion
114
.
In the case of this example having a total of twenty-two segments
112
, twenty-two coil portions are disposed at each of the upper and lower sides of the winding
111
. However, as illustrated in FIGS.
16
(
a
) to
16
(
c
), instead of inserting the coil portions
114
, which are provided correspondingly to the upper and lower sides, into the same slot, such coil portions
114
are inserted into magnetically symmetrical different slots.
Meanwhile, attention is now focused on an upper-side coil portion
114
A and a lower-side coil portion
114
B of the winding
111
connected between the segment No.
12
and the segment No.
13
of the segments
112
. The upper-side coil portion
114
A is constructed by winding a conductor a plurality of times between a slot
110
, which is formed between the tooth No.
10
and the tooth No.
11
of the teeth
113
, and another slot
110
, which is formed between the tooth No.
15
and the tooth No.
16
of the teeth
113
. Thus, this coil portion
114
A is placed nearly just above the segment No.
12
and the segment No.
13
of the segments
112
. On the other hand, the lower-side coil portion
114
B is constructed by winding a conductor a plurality of times between a slot
110
, which is formed between the tooth No.
21
and the tooth No.
22
of the teeth
113
, and another slot
110
, which is formed between the tooth No.
4
and the tooth No.
5
of the teeth
113
. Thus, this coil portion
114
B is placed nearly just above the segment No.
1
and the segment No.
2
of the segments
112
. That is, the upper-side coil portion
114
A and the lower-side coil portion
114
B, which employ the segment No.
12
as the common start point and also employ the segment No.
13
as the common end point, are apart from each other by 180 degrees in terms of a mechanical angle.
With such an arrangement, the coil portions
114
rectified with the same timing are always disposed at positions at which mechanical balance is provided, even when inconvenience occurs at the brush
108
at one side or when a subtle deviation in characteristics is caused owing to individual difference. Thus, vibrations due to an electromagnetic force are suppressed.
As is seen from
FIG. 13
, in the motor
100
of the aforementioned configuration for use in an electric power steering system, lead parts
115
B of the lower-side portion
114
of the winding
111
, which are connected to the segments
112
, become long and intersect each other. Thus, the conventional dynamo-electric machine has drawbacks in that a coil end portion of the armature
105
becomes large, that the workability in manufacturing the winding
111
by winding a conductor is low, and that defective insulation of the wiring
111
is liable to occur.
The present invention is created to eliminate the aforementioned drawbacks. Accordingly, an object of the present invention is to provide a dynamo-electric machine that prevents the lead portions of the coil portions disposed at places, at which mechanical balance is provided, from intersecting each other, that enhances the workability in manufacturing the wiring by wiring a conductor, and that suppresses the defective insulation of the winding.
SUMMARY OF THE INVENTION
To achieve the foregoing object, according to an aspect of the present invention, there is provided a dynamo-electric machine, which comprises a yoke, magnetic poles fixed in this yoke, a shaft rotatably provided in the yoke, an armature having a winding consisting of a plurality of coil portions each formed by lap-winding a conductor between a corresponding pair of slots formed in an outer circumferential surface portion of a core fixed to this shaft in such a way as to extend in an axial direction thereof, a commutator fixed to an end portion of the shaft and having a plurality of segments to which lead parts of both end sections of the coil portions are electrically connected, and brushes made to respectively abut against the surfaces of the segments o
Daikoku Akihiro
Tanaka Toshinori
Yamamoto Kyouhei
Yonemori Kei
Dougherty Thomas M.
Mitsubishi Denki & Kabushiki Kaisha
Moahndesi Iraj A.
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