U.S. patent application number 14/081419 was filed with the patent office on 2014-05-15 for stator winding and method of manufacturing the same.
The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Takashi TOKIZAWA.
Application Number | 20140132104 14/081419 |
Document ID | / |
Family ID | 50681032 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140132104 |
Kind Code |
A1 |
TOKIZAWA; Takashi |
May 15, 2014 |
STATOR WINDING AND METHOD OF MANUFACTURING THE SAME
Abstract
There is provided a winding to be wound at a stator of a rotary
electric machine. The winding is produced from a flat wire having a
rectangular cross section along a plane perpendicular to a
length-wise direction. The flat wire is coated with an electric
insulating layer and is bent to have curves at given portions of
the flat wire in the length-wise direction. The curves are located
on an axial outer side of the stator. The cross section of the flat
wire has four corners, among which mutually-adjacent two corners
are lager in curvatures than remaining mutually-adjacent two
corners. The mutually-adjacent two corners whose curvatures are
smaller are positioned on a circumferential outer side of each of
the curves and the mutually-adjacent two corners whose curvatures
are larger are positioned on a circumferential inner side of each
of the curves.
Inventors: |
TOKIZAWA; Takashi; (Nagoya,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city |
|
JP |
|
|
Family ID: |
50681032 |
Appl. No.: |
14/081419 |
Filed: |
November 15, 2013 |
Current U.S.
Class: |
310/208 ;
29/596 |
Current CPC
Class: |
H02K 3/12 20130101; H02K
15/085 20130101; H02K 15/0421 20130101; H02K 15/026 20130101; Y10T
29/49009 20150115 |
Class at
Publication: |
310/208 ;
29/596 |
International
Class: |
H02K 3/12 20060101
H02K003/12; H02K 15/04 20060101 H02K015/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2012 |
JP |
2012-250769 |
Claims
1. A winding to be wound at a stator of a rotary electric machine,
comprising: linear portions inserted in slots of the stator; and
two coil end portions respectively located on both axial sides of
the stator, wherein two of the linear portions are connected with
each other by a single intermediate portion and the two linear
portions and the intermediate portion are formed as part of each of
segments composing the winding, the intermediate portions of the
segments being projected from one of the axial sides of the stator
and formed as a coil end; the segment is formed by a flat wire
having a rectangular cross section along a plane perpendicular to a
length-wise direction of the wire and being coated with an electric
insulating layer, and the intermediate portion of each of the
segments is bent to have a curve having a circumferential direction
and a radial direction, the cross section of the flat wire has four
corners consisting of two first corners located mutually adjacently
on an inner circumferential side of the curve in the radial
direction and two second corners located mutually adjacently on an
outer circumferential side of the curve in the radial direction,
and the two first corners are lager in curvatures than the two
second corners.
2. The winding according to claim 1, wherein the two first corners
are located on the circumferential inner side and the two second
corners are located on the circumferential outer side in a state
where the winding is wound at the stator.
3. The winding according to claim 2, wherein the curves are located
outside one of the axial two ends of the stator in the axial
direction.
4. The winding according to claim 1, wherein the curves of the
segments are twisted such that the two liner portions of each of
the segments are allowed to be inserted into different layers in
different two slots of the slots.
5. A winding to be wound at a stator of a rotary electric machine,
comprising: a flat wire having a rectangular cross section along a
plane perpendicular to a length-wise direction, being coated with
an electric insulating layer, and being bent to have curves at
given portions of the flat wire in the length-wise direction, the
curves being located on an axial outer side of the stator, wherein
the cross section of the flat wire has four corners, among which
mutually adjacent two corners are lager in curvatures than
remaining mutually adjacent two corners, and the mutually adjacent
two corners whose curvatures are smaller than the others are
positioned on an outer circumferential side of each of the curves
and the mutually adjacent two corners whose curvatures are larger
than the others are positioned on an inner circumferential side of
each of the curves.
6. A method of manufacturing a winding to be wound at a stator of a
rotary electric machine, the winding comprising: linear portions
inserted in slots of the stator; and two coil end portions
respectively located on both axial sides of the stator, wherein two
of the linear portions are connected with each other by a single
intermediate portion and the two linear portions and the
intermediate portion are formed as part of each of segments
composing the winding, the intermediate portions of the segments
being projected from one of the axial sides of the stator and
formed as a coil end; the segment is formed by a flat wire having a
rectangular cross section along a plane perpendicular to a
length-wise direction of the wire and being coated with an electric
insulating layer, and the intermediate portion of each of the
segments is bent to have a curve having a circumferential direction
and a radial direction, the cross section of the flat wire has four
corners consisting of two first corners located mutually adjacently
on an inner circumferential side of the curve in the radial
direction and two second corners located mutually adjacently on an
outer circumferential side of the curve in the radial direction,
and the two first corners are lager in curvatures than the two
second corners, the method comprising steps of: preparing a round
wire with electrically insulating coating, the round wire having a
round section along a plane perpendicular to a length-wise
direction thereof; and rolling the round wire at two stages a first
rolling stage and a second rolling stage following the first
rolling stage, at the first rolling stage of which the round wire
is rolled into a deformed flat wire having an isosceles trapezoid
cross section.
7. The method according to claim 6, wherein, at the second rolling
stage, the deformed flat wire is rolled into the flat wire to be
wound at the stator.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims the benefit of
priority from earlier Japanese Patent Application No. 2012-250769
filed Nov. 15, 2012, the description of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field of the Invention
[0003] The present invention mainly relates to a stator winding for
use in a rotary electric machine, and, in particular, to such a
stator winding which is preferably used in a vehicle
alternator.
[0004] 2. Related Art
[0005] A stator winding based on conventional art for use in a
rotary electric machine is formed, for example, by bending linear
conductors that are applied with insulation coating. In bending the
linear conductors, the insulation coating is expanded in the outer
surface of a curve which is formed by bending each of the
conductors. As a result, the insulation coating is sometimes
problematically damaged (e.g., refer to patent document
JP-B-4506895).
[0006] In order to meet the recent needs of enhancing the
performance of a rotary electric machine, a stator is required to
increase the space factor in the slots. For this purpose, there is
an increasing need of using a flat wire, as a material for forming
a stator winding, which has a rectangular cross section. However,
compared to a round wire having a circular cross section, a flat
wire, when bent, causes a significant expansion in the insulation
coating in the outer surface of the curve mentioned above, and
accordingly has a high probability of suffering from damages in the
insulation coating. Therefore, additional measures may have to be
taken against this, such as increasing the thickness of the
insulation coating of the flat wire, or reinforcing the insulation
coating of the flat wire after being bent, or the like.
[0007] Further, from a standpoint of reducing cost incurred in the
materials, only round wires may be purchased and rolled into flat
wires only when used for a stator winding that is required to
achieve a high space factor.
[0008] In this case, the coating characteristics will be impaired
in the process of rolling the round wire into a flat wire.
Therefore, the probability of damaging the insulation coating will
become higher.
SUMMARY
[0009] Hence, in consideration of the foregoing, it is desired to
reduce the probability of damaging the insulation coating in the
outer surfaces of curves of a flat wire that forms a stator
winding.
[0010] As one exemplary embodiment, there is provided a winding to
be wound at a stator of a rotary electric machine. The winding is
produced from a flat wire having a rectangular cross section along
a plane perpendicular to a length-wise direction, being coated with
an electric insulating layer, and being bent to have curves (or
curved sections) at given portions of the flat wire in the
length-wise direction, the curves being located on an axial outer
side of the stator, wherein the cross section of the flat wire has
four corners, among which mutually-adjacent two corners are lager
in curvatures than remaining mutually-adjacent two corners, and the
mutually-adjacent two corners whose curvatures are smaller than the
others are positioned on a circumferential outer side of each of
the curves and the mutually-adjacent two corners whose curvatures
are larger than the others are positioned on a circumferential
inner side of each of the curves.
[0011] When a flat wire is bent, the amount of expansion of the
flat wire varies depending on the portions, such as an inner
portion or surfaces, of the flat wire. The amount of expansion
becomes smaller as the curvature becomes smaller in the corners of
the cross section of the flat wire. Therefore, the two
smaller-curvature corners are ensured to reside in the outer
surface of the curve mentioned above, in which the expansion is
significant, to minimize the amount of expansion in the insulation
coating in the outer surface. Thus, the probability of damaging the
insulation coating is reduced in the outer surface of the curve of
the stator winding that uses a flat wire as a material.
[0012] In the following description, a flat wire in which the
curvature of two adjacent corners in the cross section is larger
than that of the remaining two corners, may be referred to as a
deformed flat wire. Also, throughout the specification, when the
term "cross section" is used, it refers to a cross section
perpendicular to the longitudinal direction.
[0013] As another embodiment, there is provided a method of
manufacturing the winding according to the foregoing. The method
includes preparing a round wire with electrically insulating
coating, the round wire having a round section along a plane
perpendicular to a length-wise direction thereof; and rolling the
round wire at two stages a first rolling stage and a second rolling
stage following the first rolling stage, at the first rolling stage
of which the round wire is rolled into a deformed flat wire having
an isosceles trapezoid cross section.
[0014] Thus, further rolling is performed using the flat wire as an
intermediate material having an isosceles trapezoid cross section,
so that a deformed flat wire can be easily formed. Specifically,
plastic flow is easily caused, by rolling, in between the legs of
the isosceles trapezoid cross section, i.e. near the surface of a
portion in which the length between the legs is large. Accordingly,
the metal is permitted to plastically flow into the two corners
which are desired to have large curvature, thereby easily forming a
deformed flat wire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the accompanying drawings:
[0016] FIG. 1 is a partial perspective view illustrating a part of
a stator, according to an embodiment of the present invention;
[0017] FIG. 2 is a partial perspective view illustrating insertion
of a wire segment into a slot;
[0018] FIG. 3 is a perspective view illustrating a curved profile
of the wire segment;
[0019] FIG. 4 is a cross-sectional view taken along a line IV-IV of
FIG. 3; and
[0020] FIGS. 5A and 5B are explanatory views illustrating a first
rolling stage and a second rolling stage, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] With reference to FIGS. 1-5A and 5B, hereinafter is
described a preferred embodiment of the present invention.
[0022] With reference to the drawings, a configuration of a stator
winding 1 of the embodiment is described.
[0023] The stator winding 1 is obtained by connecting a number of
wire segments 3 (hereinafter also just referred to as segments 3),
each having a curve (or a curved section) 2, in an electrically
conductive manner. Specifically, the segments 3 before being
connected are mounted to slots 5 of a stator core 4 and deformed.
Then, predetermined connecting portions 6 of the respective
segments 3 are connected to each other in an electrically
conductive manner. In order to avoid complication, the connecting
portions in the drawings are indicated by 6Aa, 6Ba, 6Ab and 6Bb,
which will be described later, instead of being simply indicated by
6. An integral body of the stator winding 1 and the stator core 4
provided in this way forms a stator 7 of a rotary electric machine.
For example, the stator 7 is used in a vehicle alternator.
[0024] Each segment 3 is formed of a flat wire having a rectangular
cross section 11 and having a surface applied with an insulation
coating 8. For example, a flat wire is substantially bent into a
shape of a V to form the curve (or the curved section) 2 at the
bottom of the V shape.
[0025] As shown in FIG. 4 and FIGS. 5A and 5B, the rectangular
cross section 11 of the flat wire as a material of the segment 3
has four corners 12a, 12b, 12c and 12d. Of these corners, the two
adjacent corners 12a and 12b have a larger curvature than the
remaining two corners 12c and 12d. In short, the flat wire is a
deformed flat wire. In cases where each of the four corners 12a,
12b, 12c and 12d is produced as part of a circle of a radius r, the
curvature is defined as 1/r.
[0026] Specifically, for example, as shown in FIGS. 3 and 4, the
rectangular cross section 11 of the deformed flat wire as a
material of the segment 3 has two short sides 13a and 13b that are
parallel to each other. Of these short sides 13a and 13b, one short
side 13a has the two corners 12a and 12b whose curvature CV.sub.1
is made larger than that CV.sub.2 of the two corners 12c and 12d of
the other short side 13b (refer to FIG. 4). As shown in FIGS. 2 and
3, each of the curves 2 is made to have a circumferential direction
CR and a radial direction RA. For example, the short side 13a is
ensured to reside in the inner surface of the curve 2 in the radial
direction RA and the short side 13b is ensured to reside in the
outer surface of the curve 2 in the radial direction RA.
[0027] Each segment 3 includes a V-shaped portion 15 and two linear
portions 16 extending parallel to each other from the ends of the
V-shaped portion 15 to display line symmetry (see FIGS. 2 and 3).
The V-shaped portion 15 functions as an intermediate portion
connecting the two linear portions. In order to avoid complication,
the linear portions in the drawings are indicated by 16Aa, 16Ba,
16Ab and 16Bb, which will be described later, instead of being
simply indicated by 16.
[0028] Two types of the segment 3 are used here, one type being a
segment 3A having the curve 2 of a larger curvature, and the other
type being a segment 3B having the curve 2 of a smaller curvature.
The curve 2 of the segment 3A is arranged confronting the inner
surface of the curve 2 of the segment 3B. The segments 3A and 3B,
when inserted into the slots 5, form a single wire unit 17
(hereinafter also just referred to as unit 17). In the embodiment,
the curve 2 is twisted so that both linear portions of each segment
are allowed to be inserted at different layers (levels) of the
respective slots 5, as shown in FIG. 2. Hence, the circumferential
direction of each curve 2 is not parallel with that of the
stator
[0029] In one unit 17, the linear portions 16 on one side A of the
curves 2 of the respective segments 3A and 3B are inserted into a
slot 5 so as to be located radially inward of the slot, while the
linear portions 16 on the other side B of the curves 2 are inserted
into another slot 5 so as to be located radially outward of the
slot (see FIG. 2). Hereinafter, of the two linear portions 16 of
the segment 3A, the one located radially inward of the slot 5 is
referred to as a linear portion 16Aa, and the one located radially
outward of another slot 5 is referred to as a linear portion 16Ab.
Also, of the two linear portions 16 of the segment 3B, the one
located radially inward of the slot 5 is referred to as a linear
portion 16Ba, and the one located radially outward of another slot
5 is referred to as a linear portion 16Bb.
[0030] The slot 5 into which the linear portions 16Aa and 16Ba are
inserted is different from the slot 5 into which the linear
portions 16Ab and 16Bb are inserted.
[0031] These two slots 5 are interposed by two different slots 5.
Specifically, the unit 17 is outstretched on both sides of the
curve 2 in the circumferential direction and inserted into the
stator core 4, bridging three teeth 20. The linear portions 16Aa,
16Ba, 16Ab and 16Bb of the unit 17 have respective folds 19 which
are parallel to long sides 18 of the rectangular cross section 11.
The linear portions 16Aa, 16Ba, 16Ab and 16Bb are bent at the
respective folds 19 (see FIG. 4 and FIGS. 5A and 5B).
[0032] The linear portions 16Aa, 16Ba, 16Ab and 16Bb have
respective end portions which are projected from the slots 5 in the
axial direction, i.e. projected in a direction opposite to the
curve 2, to form the respective connecting portions 6. Here, the
connecting portions 6 at the ends of the linear portions 16Aa,
16Ba, 16Ab and 16Bb are designated as connecting portions 6Aa, 6Ba,
6Ab and 6Bb, respectively. The connecting portion 6Aa is connected,
in an electrically conductive manner, to the connecting portion 6Ba
of a unit 17 which is inserted into a slot 5, being interposed by
three teeth 20 on the one side A in the circumferential
direction.
[0033] The connecting portion 6Ba is connected, in an electrically
conductive manner, to the connecting portion 6Aa of a unit 17 which
is inserted into a slot 5, being interposed by three teeth 20 on
the other side B in the circumferential direction. The connecting
portion 6Ab is connected, in an electrically conductive manner, to
the connecting portion 6Bb of a unit 17 which is inserted into a
slot 5, being interposed by three teeth 20 on the other side B in
the circumferential direction. The connecting portion 6Bb is
connected, in an electrically conductive manner, to the connecting
portion 6Ab of a unit 17 which is inserted into a slot 5, being
interposed by three teeth 20 on the one side A in the
circumferential direction.
[0034] Thus, in the stator 7, the end portions of the linear
portions 16Aa, 16Ba, 16Ab and 16Bb and the V-shaped portions 15
form coil ends axially projected from both axial sides of the
stator core 4. Then, a rotor is arranged radially inside of the
stator 7 to thereby form a rotary electric machine.
[0035] Referring to FIGS. 5A and 5B, hereinafter is described a
method of fabricating the stator winding 1 of the embodiment, in
particular, a method of forming the deformed flat wire that is a
material of the wire segment 3.
[0036] The deformed flat wire is fabricated by rolling a round wire
applied with insulation coating and having a circular cross
section. In the rolling, the round wire is rolled in two stages
(two-stage rolling) using various rollers 22. In the following
description, the material supplied in a first rolling stage
performed firstly may be referred to as an initial material 23.
Also, the material resulting from the first rolling stage may be
referred to as an intermediate material 24. Further, the material
resulting from a second rolling stage may be referred to as a final
material 25.
[0037] First, a round wire is prepared as the initial material 23,
and then the intimal material 23 is subjected to the first rolling
stage.
[0038] In the first rolling stage, a round wire as the initial
material 23 is rolled into a flat wire as the intermediate material
24 whose cross section is in an isosceles trapezoid shape. Then, in
the second rolling stage, the intermediate material 24 is rolled
into a deformed flat wire as the final material 25. In a isosceles
trapezoid cross section 27 of the intermediate material 24, two
bases 28a and 28b substantially parallel to each other correspond
to the short sides 13a and 13b, respectively, in the rectangular
cross section 11 of the final material 25. Similarly, two legs 29
correspond to the long sides 18 in the rectangular cross section
11.
[0039] Further, of the two bases 28a and 28b, the longer base 28a
has two corners 30a and 30b which correspond to the two corners 12a
and 12b (i.e., two first corners), respectively, having a larger
curvature in the rectangular cross section 11. The shorter base 28b
has two corners 30c and 30d which correspond to the two corners 12c
and 12d (i.e., two second corners), respectively, having a smaller
curvature in the rectangular cross section 11.
[0040] In the second rolling stage, a portion 32 is chiefly
subjected to rolling. The portion 32 is a portion near the base
28a, in which the length between the legs 29 is large. Also, in the
second rolling stage, the deformation volume of the intermediate
material 24 is larger in the portion 32 near the base 28a between
the legs 29, than in a portion near the base 28b. Therefore, camber
is likely to be caused in the final material 25 in which the short
sides 13a and 13b reside in the outer and inner surfaces,
respectively. For this reason, in the second rolling stage, the
rollers 22 are arranged to minimize the occurrence of camber.
[0041] The stator winding 1 of the embodiment uses a deformed flat
wire as the final material 25. The deformed flat wire is bent to
form the curve 2. In bending the deformed flat wire, the two
smaller-curvature corners 12c and 12d are ensured to reside in the
outer surface of the curve 2, and the two larger-curvature corners
12a and 12b are ensured to reside in the inner surface of the curve
2.
[0042] Thus, the two smaller-curvature corners 12c and 12d are
permitted to reside in the outer surface of the curve 2, in which
the insulation coating 8 is significantly expanded by the bending.
With this configuration, expansion of the insulation coating 8 is
minimized in the outer surface of the curve 2. As a result, the
probability of damaging the insulation coating 8 is reduced in the
outer surface of the curve 2 of the stator winding 1 that uses a
flat wire as a material.
[0043] The deformed flat wire as the final material 25 is
fabricated by rolling a round wire as the initial material 23 in
two stages, the round wire having a circular cross section and
applied with insulation coating. In the preceding first rolling
stage, the round wire is rolled into the intermediate material 24
whose cross section is in an isosceles trapezoid shape.
[0044] Thus, the intermediate material 24 having a cross section in
an isosceles trapezoid shape is subjected to rolling to thereby
easily form a deformed flat wire as the final material 25.
Specifically, plastic flow is easily caused, by rolling, in between
the legs 29 of the isosceles trapezoid cross section, i.e. near the
surface of the portion 32 in which the length between the legs 29
is large. Accordingly, the metal is permitted to plastically flow
into the two corners 30a and 30b which are desired to have large
curvature, thereby easily forming a deformed flat wire.
[0045] The two-stage rolling is performed with the sequential
transition of the material from the initial material 23 to the
intermediate material 24 and further to the final material 25. In
this two-stage rolling, the final material 25 can be formed without
having to do so much rolling in the intermediate material 24 with
respect to the two corners 30c and 30d which are desired to have
smaller curvature. Thus, compared to the case where the initial
material 23 is rolled into the final material 25 without forming
the intermediate material 24, the probability of damaging the
insulation coating is further reduced in the corners 30c and
30d.
[0046] [Modifications]
[0047] The mode of the stator winding 1 and a method of fabricating
the same is not limited to the embodiment described above, but may
be variously modified.
[0048] For example, according to the fabrication method of the
embodiment, the stator winding 1 is rolled in two stages.
Alternative to this two-stage rolling, a single-stage rolling may
be performed in which the deformed flat wire as the final material
25 is fabricated from the round wire as the initial material 23,
without forming the intermediate material 24. In this case, the
number of the stages is reduced and the cost incurred in the
fabrication is reduced.
[0049] The present invention may be embodied in several other forms
without departing from the spirit thereof. The embodiment and
modifications described so far are therefore intended to be only
illustrative and not restrictive, since the scope of the invention
is defined by the appended claims rather than by the description
preceding them. All changes that fall within the metes and bounds
of the claims, or equivalents of such metes and bounds, are
therefore intended to be embraced by the claims.
* * * * *