Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1998-07-07
2001-04-17
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S208000
Reexamination Certificate
active
06218758
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 9-185371 filed on Jul. 10, 1997 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a stator of a dynamo-electric machine which is assembled by sequentially inserting premolded coil pieces into a stator core.
2. Description of the Related Art
In general, a stator of a dynamo-electric machine has a stator core
10
which is, as shown in
FIG. 7
, constituted by stacking a plurality of annular metal plates each having slots
10
a
and teeth
10
b
(a portion interposed between two teeth is called a “slot”) alternately formed along the inner periphery thereof. The stator further has coils
12
, each of which is formed by continuously winding a coil wire coated with enamel or the like around the tooth
10
b
of the stator core
10
. The stator shown in
FIG. 7
is formed by a winding method which is so-called concentrated winding. In this method, one coil
12
is provided for one tooth
10
b
. One or a plurality of bundled wires each having a diameter ranging from about 0.5 mm to about 1.0 mm are wound around a tooth
10
b
a predetermined number of times. Therefore, the slot
10
a
is designed to receive adjacent ends of two coils fitted to two teeth
10
b
interposing the slot
10
a
. When an electric current is allowed to pass through each coil
12
, a magnetic flux is generated in a direction along which the magnetic flux penetrates the coil
12
through the teeth
10
b
serving as a magnetic path. As a result, a rotor (not shown) can be rotated. The dynamo-electric machine acts as a dynamo-electric generator by rotating the rotor with the aid of an external force.
Generally it takes a long time to wind the coil wire around each tooth
10
b
as described above. Additionally it is difficult to automate such winding operation. Japanese Utility-Model Publication No. 2524074 discloses a structure arranged such that coil pieces, which have been molded to have a predetermined shape using a mold or the like, are fitted with the teeth
10
b
. In this case, the slots
10
a
accommodate the coil pieces, each of which is formed by winding a coil wire predetermined number of times across the teeth
10
b
. Therefore, the operation for assembling the stator can easily be completed. Moreover, the operation for winding the coil wire can easily be automated.
When the slots
10
a
for accommodating the coil pieces are formed along the inner periphery of the stator core
10
as shown in
FIG. 7
, the width of the open portion (the upper portion) of each slot
10
a
is smaller than that of the bottom portion (the lower portion) of the slot
10
a
. That is, the slot
10
a
has a shape which is gradually widened toward the bottom portion thereof. Therefore, the cross sectional width of the coil piece which is inserted into the slot
10
a
must be equal to or smaller than the width of the open portion of the slot
10
a
so as to prevent interference with a leading end of the tooth
10
b
. As a result, there is undesirable space formed within the slot
10
a
after inserting the coil piece having the above described shape into the slot
10
a
. Thus, the required space factor in the slot
10
a
cannot be obtained, resulting in problems such as deteriorated performance of the dynamo-electric machine.
It might be considered feasible to form each of the teeth
10
b
into a trapezoidal shape so as to form the slot
10
a
into a rectangular shape, as shown in FIG.
8
. In this case, the coil pieces
14
must be gradually widened so as to be fitted with the trapezoidal teeth
10
b
. However, the coil pieces
14
, each of which is formed by winding the coil wire a plural number of times, are too rigid to be widened as described above. Thus, there arises a problem in that fitting operation while widening the coil pieces is very difficult.
Another method has been suggested which has the steps of fitting the coil pieces
14
with sectioned portions of the stator core
10
, and combining the sectioned portions of the stator core
10
with one another by welding or the like. Using the above-mentioned method, however, may deteriorate rigidity of the stator itself and fail to keep the accuracy of the shape to a predetermined level or more. This may result in deterioration of the dynamo-electric machine.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a stator of a dynamo-electric machine which is capable of raising the space factor in slots thereof and which can easily be assembled.
To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a stator of a dynamo-electric machine formed of an annular stator core having a plurality of slots and teeth alternately formed along the inner periphery thereof and a plurality of coil pieces which can sequentially be inserted into the slots across the teeth. The coil pieces include first coil pieces, each having a cross sectional shape arranged such that the width of the coil at the lower portion of the slot is equal to or smaller than the width of the inner periphery of two adjacent slots. One side of the coil piece facing a tooth adjacent to the tooth fitted with the coil piece extends substantially parallel with the side of the adjacent tooth or is located such that the width of the upper portion of the slot is gradually increased from the lower portion. The coil pieces further include second coil pieces, each of which is fitted to a tooth adjacent to the tooth to which the first coil piece is fitted so as to be inserted into an empty space in the slot formed after the first coil piece has been inserted for filling the empty space.
The lower portion of the slot refers to a bottom portion thereof located along the outer periphery of the stator core, while the upper portion of the slot refers to an open portion thereof located close to the center of the stator core.
According to the above-mentioned structure, the empty space in the slot which is formed after the first coil piece has been inserted is located parallel with the teeth adjacent to the tooth fitted with the first coil piece or has further widened upper portion. Therefore, the second coil piece can easily be inserted into the slot without interference with other teeth. Moreover, the space in the slot can easily be filled and thus the space factor can be raised.
The embodiment of the present invention may be structured such that the slot has an upper portion which is narrower than the lower portion. The tooth adjacent to the tooth to which the first coil piece is fitted may have a tapered leading end. As a result, the coil pieces can be fitted easily.
The embodiment of the present invention may be structured such that the cross section of the first coil piece is formed as a trapezoidal shape, and the cross section of the second coil piece is formed as a parallelogram shape. As a result of the above-mentioned structure, the internal space of each slot having the widened lower portion can easily be filled with two types of coil pieces having simple shapes.
In the embodiment of the present invention, each coil piece is formed by alternately winding copper wires, each having a circular cross section, and pressing the wound copper wires. Thus, the space factor in the slot can be raised and therefore the performance of the dynamo-electric machine can be improved.
The embodiment of the present invention may be structured such that each coil piece is formed by winding a copper wire having a rectangular cross section. Each coil piece formed by winding the copper wire having the rectangular cross section may be formed by shifting the winding position or performing a pressing process after the winding process has been performed. As a result, the space factor in the slot can be raised compared with the wire having a circular cross section. The performance of the dynamo-electric machine thus can be
Kwabata Yasutomo
Miura Tetsuya
Mizutani Ryoji
Sugimoto Tetsuya
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Perez Guillermo
Ramirez Nestor
Toyota Jidosha & Kabushiki Kaisha
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