U.S. patent application number 10/443650 was filed with the patent office on 2004-06-24 for stator winding having cascaded end loops and increased cooling surface area.
Invention is credited to Neet, Kirk E..
Application Number | 20040119360 10/443650 |
Document ID | / |
Family ID | 31188208 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040119360 |
Kind Code |
A1 |
Neet, Kirk E. |
June 24, 2004 |
STATOR WINDING HAVING CASCADED END LOOPS AND INCREASED COOLING
SURFACE AREA
Abstract
A dynamoelectric machine stator winding having cascaded end
loops and increased cooling surface area is adapted to be placed in
a plurality of circumferentially spaced axially-extending core
slots in a surface of a generally cylindrically-shaped stator core.
The stator winding includes a plurality of straight segments
alternately connected at the first and second ends of the stator
core by a plurality of end loop segments to form the winding. The
end loops include first and second sloped sides meeting at an apex
portion. The first and second sloped sides include at least one
body portion offset in opposite radial directions to form a
cascaded winding pattern and providing increased cooling surface
area for the winding.
Inventors: |
Neet, Kirk E.; (Saline,
MI) |
Correspondence
Address: |
MACMILLAN, SOBANSKI & TODD, LLC
ONE MARITIME PLAZA-FOURTH FLOOR
720 WATER STREET
TOLEDO
OH
43604
US
|
Family ID: |
31188208 |
Appl. No.: |
10/443650 |
Filed: |
May 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10443650 |
May 22, 2003 |
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10324319 |
Dec 19, 2002 |
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Current U.S.
Class: |
310/201 ;
310/208 |
Current CPC
Class: |
H02K 3/12 20130101; H02K
3/24 20130101 |
Class at
Publication: |
310/201 ;
310/208 |
International
Class: |
H02K 001/00; H02K
003/00 |
Claims
What is claimed is:
1. A stator for a dynamoelectric machine, comprising: a generally
cylindrically-shaped stator core having a plurality of
circumferentially spaced axially-extending core slots in a surface
thereof, said core slots extending between a first and a second end
of said stator core; and a stator winding including at least one
layer of conductors having a plurality of phases, wherein said at
least one layer of said phases includes substantially straight
segments disposed in a plurality of said core slots that are
located at the same radial distance from the central axis of the
stator core having end loop portions connecting two straight
segments of said phase, wherein said end loop segments form a
cascaded winding pattern while keeping said end loop segments
substantially radially within their respective layer, and wherein
said straight segments have a circumferential width C1 and said end
loop segments have a circumferential width C2 less than said
circumferential width C1, and wherein at least one of said phases
is radially shifted.
2. The stator according to claim 1 wherein said end loop segments
of said phases include a first sloped side and a second sloped side
that meet at an apex portion.
3. The stator according to claim 2 wherein at least one of said
sloped sides of said end loop segments includes an offset body
portion.
4. The stator according to claim 3 wherein at least one of said
offset body portions is offset in a first radial direction and at
least another of said offset body portions is offset in a second
radial direction opposite said first radial direction.
5. The stator according to claim 4 wherein at least one of said
sloped sides includes a body portion with a first body section
offset in said second radial direction and a second body section
offset in said first radial direction, a radial transition between
said first and second body sections being placed in response to a
crossing point of another phase.
6. The stator according to claim 5 wherein said stator winding
includes a first phase, a second phase, a third phase, a fourth
phase, a fifth phase and a sixth phase, and wherein said sloped
sides of said first phase each include a body portion offset
exclusively in a first radial direction, and wherein a one of said
sloped sides of said second phase includes a body portion offset
exclusively in said first radial direction, and wherein the other
of said sloped sides of said second phase includes a body portion
with a first body section offset in a second radial direction
opposite said first radial direction and a second body section
offset in said first radial direction, a radial transition between
said first and second body sections being placed in response to a
crossing point of said first phase, and wherein one of said sloped
sides of said third phase includes a body portion offset
exclusively in said first radial direction, wherein the other of
said sloped sides of said third phase includes a body portion
offset exclusively in said second radial direction, wherein said
end loop segments of said fourth phase are substantially identical
to said end loop segments of said third phase, and wherein one of
said sloped sides of said fifth phase includes a body portion
offset exclusively in said second radial direction, and wherein the
other of said sloped sides of said fifth phase includes a body
portion with a first body section offset in a first radial
direction and a second body section offset in said second radial
direction, a radial transition between said first and second body
sections being placed in response to a crossing point of a sixth
phase, and wherein said sloped sides of said sixth phase each
include a body portion offset exclusively in said second radial
direction.
7. The stator according to claim 1 wherein each of said straight
segments has a first substantially rectangular cross-sectional
shape, wherein each of said first sloped sides has a second
substantially rectangular cross-sectional shape and wherein each of
said second sloped sides has a third substantially rectangular
cross-sectional shape.
8. The stator according to claim 7 wherein an area of said second
cross-sectional shape area is equal to an area of said third
rectangular cross-sectional shape.
9. The stator according to claim 7 wherein an area of said first
cross-sectional shape is equal to said area of said second
cross-sectional shape and said area of said third cross-sectional
shape.
10. The stator according to claim 7 wherein a one of said second
cross-sectional shape and said third cross-sectional shape is equal
to substantially one half of said area of said first
cross-sectional shape.
11. The stator according to claim 1 wherein said stator core slots
have a generally rectangular volume.
12. The stator according to claim 1 wherein the width, including
any insulation of said straight segments of said stator winding fit
closely to the width, including any insulation, of said stator core
slots.
13. The stator according to claim 1 wherein said stator winding
includes at least two layers of conductors.
14. The stator according to claim 13 wherein said straight segments
of said layers are positioned in one radial row in each slot.
15. A method for forming a winding a stator of a dynamoelectric
machine, comprising the steps of: a) providing a stator winding
having at least three continuous phases, each of said phases of
said stator winding being formed from a wire having a rectangular
cross section, b) forming a first phase wherein said first phase
has straight segments connected by a plurality of end loops,
wherein end loops of said first phase are substantially identical
and include first and second sloped sides meeting at an apex
portion, wherein said sloped side each include a body portion
offset exclusively in a first radial direction; c) forming a second
phase wherein said second phase has straight segments connected by
a plurality of end loops, wherein end loops of said second phase
are substantially identical and include first and second sloped
sides meeting at an apex portion, wherein one of said sloped sides
includes a body portion offset exclusively in said first radial
direction, and wherein the other of said sloped sides includes a
body portion with a first body section offset in a second radial
direction opposite said first radial direction and a second body
section offset in said first radial direction, a radial transition
between said first and second body sections being placed in
response to a crossing point of said first phase; d) forming a
third phase wherein said third phase has straight segments
connected by a plurality of end loops, wherein end loops of said
third phase are substantially identical and include first and
second sloped sides meeting at an apex portion, wherein one of said
sloped sides includes a body portion offset exclusively in said
first radial direction, wherein the other of said sloped sides
includes a body portion offset exclusively in said second radial
direction; e) providing a generally cylindrically-shaped stator
core having a plurality of circumferentially spaced
axially-extending core slots in a surface thereof, said core slots
extending between a first and a second end of said stator core; f)
inserting said third phase in a plurality of said core slots
beginning at a first core slot and incrementally around said stator
core at a predetermined pitch; g) inserting said second phase in a
plurality of said core slots beginning at a second core slot and
incrementally around said stator core at said predetermined pitch,
h) inserting said first phase in a plurality of said core slots
beginning at a third core slot and incrementally around said stator
core at said predetermined pitch, said phases forming a cascaded
winding pattern, said stator winding providing increased cooling
surface area, and wherein at least one of said phases is radially
shifted.
16. The method according to claim 15 wherein in step b) said
straight segments are formed having a first substantially
rectangular cross-sectional shape and said end loops are formed
having a second substantially rectangular cross-sectional shape
17. The method according to claim 15 wherein in step b) each of
said straight segments are formed having a first substantially
rectangular cross-sectional shape, each of said first sloped sides
are formed having a second substantially rectangular
cross-sectional shape and each of said second sloped sides are
formed having a third substantially rectangular cross-sectional
shape.
18. The method according to claim 17 wherein in step b) an area of
said first cross-sectional shape, an area of said second
cross-sectional shape, and an area of said third cross-sectional
shape are formed substantially equal.
19. The method according to claim 17 wherein an area of said second
substantially rectangular cross section formed in step b) is
substantially one half of an area of said first substantially
rectangular cross section.
20. The method according to claim 17 wherein in step b) said stator
winding is formed in at least two layers of conductors.
21. A dynamoelectric machine, comprising: a housing; a shaft
rotatably supported by said housing; a rotor supported by and
adapted to rotate with said shaft; and a stator fixedly disposed in
said housing adjacent said rotor, said stator comprising: a
generally cylindrically-shaped stator core having a plurality of
circumferentially spaced axially-extending core slots in a surface
thereof, said core slots extending between a first and a second end
of said stator core; and a stator winding including at least one
layer of conductors having at least six phases, wherein a first
phase has straight segments disposed in a plurality of said core
slots beginning at a first slot and incrementally around said
stator core at a predetermined pitch, wherein end loops of said
first phase are substantially identical and include first and
second sloped sides meeting at an apex portion, wherein said sloped
sides each include a body portion offset exclusively in a first
radial direction, and wherein a second phase has straight segments
disposed in a plurality of said core slots beginning at a second
slot and incrementally around said stator core at said
predetermined pitch, wherein end loops of said second phase are
substantially identical and include first and second sloped sides
meeting at an apex portion, wherein one of said sloped sides
includes a body portion offset exclusively in said first radial
direction, and wherein the other of said sloped sides includes a
body portion with a first body section offset in a second radial
direction opposite said first radial direction and a second body
section offset in said first radial direction, a radial transition
between said first and second body sections being placed in
response to a crossing point of said first phase, and wherein a
third phase has straight segments disposed in a plurality of said
core slots beginning at a third slot and incrementally around said
stator core at said predetermined pitch, wherein end loops of said
third phase are substantially identical and include first and
second sloped sides meeting at an apex portion, wherein one of said
sloped sides includes a body portion offset exclusively in said
first radial direction, wherein the other of said sloped sides
includes a body portion offset exclusively in said second radial
direction, and wherein a fourth phase has straight segments
disposed in a plurality of said core slots beginning at a fourth
slot and incrementally around said stator core at said
predetermined pitch and includes end loops substantially identical
to said end loops of said third phase, and wherein a fifth phase
has straight segments disposed in a plurality of said core slots
beginning at a fifth slot and incrementally around said stator core
at said predetermined pitch, wherein end loops of said fifth phase
are substantially identical and include first and second sloped
sides meeting at an apex portion, wherein one of said sloped sides
includes a body portion offset exclusively in said second radial
direction, and wherein the other of said sloped sides includes a
body portion with a first body section offset in a first radial
direction and a second body section offset in said second radial
direction, a radial transition between said first and second body
sections being placed in response to a crossing point of a sixth
phase, and wherein said sixth phase has straight segments disposed
in a plurality of said core slots beginning at a sixth slot and
incrementally around said stator core at said predetermined pitch,
wherein end loops of said sixth phase are substantially identical
and include first and second sloped sides meeting at an apex
portion, wherein said sloped sides each include a body portion
offset exclusively in said second radial direction wherein each of
said end loops form a cascaded winding pattern and keeping said end
loops radially within their respective layer, and wherein at least
one of said phases is radially shifted and said stator winding
exhibits improved cooling by providing increased cooling surface
area.
22. The dynamoelectric machine according to claim 21 wherein said
stator core slots have a generally rectangular volume.
23. The dynamoelectric machine according to claim 21 wherein the
width, including any insulation of said straight segments of said
stator winding fit closely to the width, including any insulation,
of said stator core slots.
24. The dynamoelectric machine according to claim 21 wherein said
stator winding includes at least two layers of conductors.
26. The dynamoelectric machine according to claim 24 wherein said
straight segments of said layers are positioned in one radial row
in each slot.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 10/324,319 filed Dec. 19,
2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to stators for
dynamoelectric machines and, in particular, to an stator winding
for a dynamoelectric machine having cascaded end loops and an
increased cooling surface area.
[0003] Dynamoelectric machines, such as alternating current
electric generators, or alternators, are well known. Prior art
alternators typically include a stator assembly and a rotor
assembly disposed in an alternator housing. The stator assembly is
mounted to the housing and includes a generally
cylindrically-shaped stator core having a plurality of slots formed
therein. The rotor assembly includes a motor rotor attached to a
generally cylindrical shaft that is rotatably mounted in the
housing and is coaxial with the stator assembly. The stator
assembly includes a plurality of wires wound thereon, forming
windings.
[0004] In one relatively new type of stator known as a high slot
fill stator, the stator windings are formed of substantially
straight portions that are located in the slots and end loop
sections that connect two adjacent straight portions of the same
phase and are formed in a predetermined multi-phase (e.g. three or
six) winding pattern in the slots of the stator core. The rotor
assembly typically includes opposed poles as part of claw fingers
that are positioned around an electrically charged rotor coil. The
rotor coil produces a magnetic field. When a prime mover, such as a
steam turbine, a gas turbine, or a drive belt from an automotive
internal combustion engine, rotates the rotor assembly, the
magnetic field of the rotor assembly passes through the stator
windings, inducing an alternating electrical current in the stator
windings in a well known manner. The alternating electrical current
is then routed from the alternator to a distribution system for
consumption by electrical devices or, in the case of an automotive
alternator, to a rectifier and then to a charging system for an
automobile battery.
[0005] The high slot fill stator is characterized by rectangular
core slots and rectangular shaped conductors. The width, including
any insulation, of the rectangular shaped conductors fit closely to
the width, including any insulation, of the rectangular core slots.
High slot fill stators are advantageous because they are efficient
and help produce more electrical power per winding than other types
of prior art stators. These stators, however, are disadvantageous
because the windings are typically interlaced, in which the wires
are required to alternate between outer and inner radial layers of
each slot. These interlaced windings require an interlacing process
to interlace the conductors of all the phases prior to inserting
the winding into the core and therefore disadvantageously increase
the complexity of placing the winding the stator. Other prior art
stators have utilized hairpin conductors, in which separate
U-shaped conductor pieces are placed in the core slots from an
upper or lower axial end of the stator core and then welded
together. While the hairpin conductors are not interlaced, the
difficulty of manufacturing the stators is still increased because
the opposing ends of the U-shaped conductors must be welded to form
the stator winding.
[0006] During operation of the alternator, the stator windings
increase in temperature as a result of the induced electrical
current flowing through the winding resistance. As the stator
windings increase in temperature, the efficiency of the alternator
disadvantageously decreases.
[0007] It is desirable, therefore, to provide a stator having a
winding that meets the requirements of a high slot fill stator but
does not require the complex interlaced winding process or the
hairpin conductors of the prior art. It is also desirable to
provide a stator for a dynamoelectric machine that can provide
improved cooling for the stator winding.
SUMMARY OF THE INVENTION
[0008] A stator winding for a dynamoelectric machine, such as an
alternator, having cascaded end loops and increased cooling surface
area is adapted to be placed in a plurality of circumferentially
spaced axially-extending core slots in a surface of a generally
cylindrically-shaped stator core. The stator winding includes a
plurality of substantially straight segments alternately connected
at the first and second ends of the stator core by a plurality of
end loops or end loop segments to form the winding. The end loops
include first and second sloped sides meeting at an apex portion.
The first and second sloped sides include at least one body portion
offset in opposite radial directions. Each of the end loop segments
form a cascaded winding pattern allowing sequential phase
insertion, defined in more detail below and causing no interference
between the end loop segments of each of the phases and providing
increasing cooling surface area for the winding.
[0009] Preferably, the stator winding in accordance with the
present invention advantageously provides improved cooling by
shifting a predetermined number of phases to provide increased
cooling surface area.
[0010] Preferably, the straight segments have a first
cross-sectional shape wherein the area of the first cross-sectional
shape of the straight segments is preferably substantially equal to
the area of the cross-sectional shape of the end loop segments.
Alternatively, the area of the cross-sectional shape of the
straight segments is substantially double the area of the
cross-sectional shape of the end loop segments.
DESCRIPTION OF THE DRAWINGS
[0011] The above, as well as other advantages of the present
invention, will become readily apparent to those skilled in the art
from the following detailed description of a preferred embodiment
when considered in the light of the accompanying drawings in
which:
[0012] FIG. 1 is a perspective view of a stator core in accordance
with the present invention;
[0013] FIG. 2 is a perspective view of a stator winding in
accordance with the present invention;
[0014] FIG. 3 is a schematic view of the stator winding shown in
FIG. 1;
[0015] FIG. 4 is a cross-sectional view of a straight segment of
the stator winding taken along line 4-4 in FIG. 3;
[0016] FIG. 5 is a cross-sectional view of an end loop segment of
the stator winding taken along line 5-5 in FIG. 3; and
[0017] FIG. 6 is a cross-sectional view of an dynamoelectric
machine in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] Referring now to FIG. 1, a generally cylindrically-shaped
stator core is indicated generally at 10. The stator core 10
includes a plurality of core slots 12 formed in a circumferential
interior surface 14 thereof. The core slots 12 are generally
rectangular in cross section and extend in a direction, indicated
by an arrow 16, parallel to a central axis 17 of the stator core 10
between a first end 18 and a second end 20 thereof. The core slots
12 have a generally rectangular volume. An axially upward direction
is defined as moving toward the first end 18 of the stator core 10
and an axially downward direction is defined as moving toward the
second end 20 of the stator core 10. Preferably, the core slots 12
are equally spaced around the circumferential interior surface 14
of the stator core 10. A circumferential clockwise direction is
indicated by an arrow 21 and a circumferential counterclockwise
direction is indicated by an arrow 23. The core slots 12 define a
depth 25 along a radial axis, indicated by an arrow 24, and are
adapted to receive a stator winding, discussed in more detail
below. A radial inward direction is defined as moving towards the
central axis 17 of the stator core 10 and a radial outward
direction is defined as moving away from the central axis 17.
Alternatively, the core slots 12 may be formed in an exterior
surface of the stator core 10, allowing for external insertion of
the conductors into the core slots.
[0019] Referring now to FIGS. 2-5, a plurality of phase portions
are indicated generally at 30, 32, 34, 36, 38 and 40 that form a
continuous layer of a six phase stator winding, indicated generally
at 42. Preferably, each of the phase portions 30, 32, 34, 36, 38
and 40 are formed of rectangular wire. Those skilled in the art
will recognize that the phase portions 30, 32, 34, 36, 38 and 40
may also be formed of square wire (not shown) or rectangular wire
with radii on the corners of the wire (not shown). Each of the
phase portions 30, 32, 34, 36, 38 and 40 include a plurality of
substantially identical straight segments 44, each of which is
adapted to be received in a respective axially-extending core slot
12 of the stator core 10. The straight segments 44 are all located
at the same radial distance from the central axis 17 of the stator
core 10 and form a layer of the stator winding, indicated generally
at 46. While the straight segments 44 of the phase portions 30, 32,
34, 36, 38 and 40 are shown generally coplanar in FIG. 2 for
illustrative purposes, the straight segments 44 of the phase
portions 30, 32, 34, 36, 38 and 40 are preferably adapted to be
received by a radially curved surface, such as the interior surface
14 of the stator core 10 and, therefore, are not coplanar (i.e.,
the circumferential layer 46 is flattened into a plane in FIG. 2)
but are are co-radial. The term co-radial, as utilized herein, is
defined as two objects being at the same radial distance from an
axis, such as the central axis of the stator core, and in the same
cylindrical surface.
[0020] Each of the straight segments 44 has a first rectangular
cross-sectional shape defined by a radial depth R1, and a
circumferential width C1 and including any radii between the depths
R1 and the widths C1 (not shown). An area A1, of the first
rectangular cross-sectional shape of the straight segment 44, is
defined by the dimensions R1 and C1 including any radii between R1
and C1, best seen in FIG. 4. Each of the straight segments 44,
therefore, has the first rectangular cross sectional shape with an
area A1.
[0021] The straight segments 44 of the first phase 30 are connected
at the alternate axial ends 18 and 20 of the stator core 10 by a
plurality of identical end loops or end loop segments 48 to form a
continuous layer of a phase of the stator winding 42. The straight
segments 44 of the first phase 30 are disposed in a plurality of
core slots 12 beginning at a first slot (not shown) and
incrementally around the stator core 10 at a predetermined pitch.
Each of the end loop segments 48 of the first phase 30 include a
first sloped portion or side 50 and a second sloped portion or side
52 connected to a respective straight segment 44 at one end
thereof. The first sloped side 50 and the second sloped side 52
meet at an apex portion 54. On those end loop segments 48 at the
second axial end 20 of the stator core 10, the first sloped side 50
extends in the circumferential clockwise direction 21 and in the
axially downward direction from a lower portion of a straight
segment 44. The first sloped side 50 includes an offset body
portion 51 wherein the radially inward edge of the offset body
portion 51 is at the same radial location as the radially inward
edge of the straight segments 44 but the radially outward edge of
offset body portion 51 is offset a predetermined distance in the
radially inward direction. The second sloped side 52 extends in the
circumferential counterclockwise direction 23 and in the axially
downward direction from a lower portion of a second straight
segment 44. The second sloped side 52 includes an offset body
portion 53 wherein the radially inward edge of the offset body
portion 53 is at the same radial location as the radially inward
edge of the straight segment 44 but the radially outward edge of
the offset body portion 53 is offset a predetermined distance in
the radially inward direction. The predetermined distance for the
offset portion 51 of the first sloped side 50 and the offset
portion 53 of the second sloped side 52 is substantially equal to
the respective lengths of the first sloped side 50 and the second
sloped side 52.
[0022] Similarly, on those end loop segments 48 at the first axial
end 18 of the stator core 10, the first sloped side 50 extends in
circumferential clockwise direction 21 and in the axially upward
direction from an upper portion of a straight segment 44. The first
sloped side 50 includes the offset body portion 51 wherein the
radially inward edge of the offset body portion 51 is at the same
radial location as the radially inward edge of the straight
segments 44 but the radially outward edge of offset body portion 51
is offset a predetermined distance in the radially inward
direction. The second sloped side 52 extends in the circumferential
counterclockwise direction 23 and in the axially upward direction
from an upper portion of the straight segment 44. The second sloped
side 52 includes the offset body portion 53 wherein the radially
inward edge of the offset body portion 53 is at the same radial
location as the radially inward edge of the straight segments 44
but the radially outward edge of the offset body portion 41 is
offset a predetermined distance in the radially inward direction.
The predetermined distance for the offset portion 51 of the first
sloped side 50 and the offset portion 53 of the second sloped side
52 is substantially equal to the respective lengths of the first
sloped side 50 and the second sloped side 52.
[0023] The second sloped side 52 has a radial depth R2 and a
circumferential width C2, best seen in FIG. 5. An area A2 of the
rectangular cross-sectional shape of the second sloped side 52, is
defined by the dimensions R2 and C2 including any radii between R2
and C2, best seen in FIG. 5. The area A2 of the second sloped side
52 is substantially equal to the area A1 of the straight segment
44. Preferably, the length of R2 is substantially half the length
of R1, as seen in FIG. 2 and the length of C2 is substantially
twice the length of the C1, as seen in FIG. 3. The first sloped
side 50 has a substantially rectangular cross-sectional shape (not
shown). Preferably, the area of the cross-sectional shape of the
first sloped side 50 is substantially equal to the area A1 of the
straight segment 44 and the area A2 of the second sloped side 52.
Those skilled in the art, however, will appreciate that the length
and width of the first sloped side 50 and the second sloped side 52
of the end loop segments 48 may be varied in any number of
combinations to produce an area A2 that is substantially equal to
A1 in order to provide constant electrical resistance throughout
the length of the phase portion 30 while avoiding interference
between cascaded end loops of adjacent phases as described
below.
[0024] Alternatively, the end loop segments 48 have a
cross-sectional shape having an area A2 that is substantially equal
to one half of the area A1 of the first cross-sectional shape.
Preferably, this is accomplished by forming the side R2 equal to
substantially one half the length of the side R1 and by forming the
side C2 equal to substantially the length of the side C1, as could
be obtained by simple die cutting of the wire.
[0025] The straight segments 44 of the second phase 32 are
connected at the alternate axial ends 18 and 20 of the stator core
10 by a plurality of identical end loop segments 56 to form a
continuous layer of a phase of the stator winding 42. The straight
segments 44 of the second phase 32 are disposed in a plurality of
core slots 12 beginning at a second slot (not shown) and
incrementally around the stator core 10 at a predetermined pitch.
Each of the end loop segments 56 of the second phase 32 include a
first sloped side 58 and a second sloped side 60 connected to a
respective straight segment 44 at one end thereof. The first sloped
side 58 and the second sloped side 60 meet at another respective
end at an apex portion 62. On those end loop segments 56 at the
second axial end 20 of the stator core 10, the first sloped side 58
extends in the circumferential clockwise direction 21 and in the
axially downward direction from a lower portion of a straight
segment 44. The first sloped side 58 includes a first offset body
portion 57 wherein the radially inward edge of the offset body
portion 57 is at the same radial location as the radially inward
edge of the straight segments 44 but the radially outward edge of
offset body portion 57 is offset a predetermined distance in the
radially inward direction. The first sloped side 58 also includes a
second offset body portion 59 wherein the radially outward edge of
the offset body portion 59 is at the same radial location as the
radially outward edge of the straight segments 44 but the radially
inward edge of offset body portion 59 is offset a predetermined
distance in the radially outward direction. The first offset body
portion 57 and the second offset body portion 59 are connected by a
radial transition portion 76. The radial transition portion 76 is
placed on the end loop segment 56 in response to a crossing point
of the sixth phase 40. The second sloped side 60 extends in the
circumferential counterclockwise direction 23 and in the axially
downward direction from a lower portion of a straight segment 44.
The second sloped side 60 includes an offset body portion 61
wherein the radially inward edge of the offset body portion 61 is
at the same radial location as the radially inward edge of the
straight 44 but the radially outward edge of the offset body
portion 61 is offset a predetermined distance in the radially
inward direction. The predetermined distance for the offset
portions 57 and 59 of the first sloped side 58 and the offset
portion 61 of the second sloped side 60 is sufficient to avoid
interfering with the end loop segments of the phases 30, 34, 36,
38, and 40 on the second axial end 20, discussed in more detail
below.
[0026] Similarly, on those end loop segments 58 at the first axial
end 18 of the stator core 10, the first sloped side 60 extends in
circumferential clockwise direction 21 and in the axially upward
direction from an upper portion of a straight segment 44. The first
sloped side 60 includes the first offset body portion 57 wherein
the radially inward edge of the offset body portion 57 is at the
same radial location as the radially inward edge of the straight
segments 44 but the radially outward edge of the offset body
portion 57 is offset a predetermined distance in the radially
inward direction. The first sloped side 58 includes the second
offset body portion 59 wherein the radially outward edge of the
offset body portion 59 is at the same radial location as the
radially outward edge of the straight segments 44 but the radially
inward edge of offset body portion 59 is offset a predetermined
distance in the radially outward direction. The first offset body
portion 57 and the second offset body portion 59 are connected by
the radial transition portion 76. The radial transition portion 76
is placed on the end loop segment 56 in response to a crossing
point of the sixth phase 40. The second sloped side 60 extends in
the circumferential counterclockwise direction 23 and in the
axially upward direction from an upper portion of the straight
segment 44. The second sloped side 60 includes the offset body
portion 61 wherein the radially inward edge of the offset body
portion 61 is at the same radial location as the radially inward
edge of the straight segments 44 but the radially outward edge of
the offset body portion 61 is offset a predetermined distance in
the radially inward direction. The predetermined distance for the
offset portions 57 and 59 of the first sloped side 58 and the
offset portion 61 of the second sloped side 60 is sufficient to
avoid interfering with the end loop segments of the phases 30, 34,
36, 38, and 40 on the first axial end 18, discussed in more detail
below.
[0027] Preferably, an area (not shown) of the cross-sectional shape
of the first sloped side 58 and the second sloped side 60 is
substantially equal to the area A1 of the straight segment 44 and
the area A2 of the second sloped side 52.
[0028] The straight segments 44 of the third phase 34 are connected
by a plurality of end loop segments 64 and the straight segments 44
of the fourth phase 36 are connected by a plurality of identical
end loop segments 66. The straight segments 44 of the third phase
34 are disposed in a plurality of core slots 12 beginning at a
third slot (not shown) and incrementally around the stator core 10
at a predetermined pitch. The straight segments 44 of the fourth
phase 36 are disposed in a plurality of core slots 12 beginning at
a fourth slot (not shown) and incrementally around the stator core
10 at a predetermined pitch. The end loop segments 64 and 66 are
substantially identical and include a first sloped side 78 and a
second sloped side 80 that meet at an apex portion 82 thereof.
Preferably, each of the end loop segments 64 and 66 of the third
phase 34 and fourth phase 36, respectively, includes an offset body
portion 79 on the first sloped side 78 and an offset body portion
81 on the second sloped side 82 thereof. The offset body portion 79
is in the radial outward direction and the offset body portion 81
is in the radial inward direction. The length of the offset body
portions 79 and 81 on the end loop segments 64 and 66 is sufficient
to cause no interference with the end loop segments of adjacent
phases.
[0029] The straight segments 44 of the fifth phase 38 are connected
by a plurality of identical end loop segments 68. The straight
segments 44 of the fifth phase 38 are disposed in a plurality of
core slots 12 beginning at a fifth slot (not shown) and
incrementally around the stator core 10 at a predetermined pitch.
The end loop segments 68 include a first sloped side 84 and a
second sloped side 86 that meet at an apex portion 88 thereof.
Preferably, each of the end loop segments 66 of the fifth phase 36
are similar to the end loop segments 56 of the second phase 32
wherein the end loop segments 66 include a first offset body
portion 83 and a second offset body portion 85 on the second sloped
side 86 that are connected by a radial transition portion 89 and an
offset body portion 87 on the first sloped side 84 thereof. The
offset body portions 85 and 87 are in the radial outward direction
and the offset body portion 83 is in the radial inward
direction.
[0030] The straight segments 44 of the sixth phase 40 are connected
by a plurality of identical end loop segments 70. The straight
segments 44 of the sixth phase 40 are disposed in a plurality of
core slots 12 beginning at a sixth slot (not shown) and
incrementally around the stator core 10 at a predetermined pitch.
The end loop segments 70 include a first sloped side 90 and a
second sloped side 92 that meet at an apex portion 94 thereof.
Preferably, each of the end loop segments 70 of the sixth phase 40
are similar to the end loop segments 48 of the first phase 30
wherein the first sloped side 90 includes an offset body portion 91
and the second sloped side 92 includes an offset body portion 93.
Each of the offset body portions 91 and 93 are offset in the radial
outward direction. The length of the offset body portions 91 and 93
of the end loop segments 70 is substantially equal to the
respective lengths of the first sloped side 90 and the second
sloped side 92 thereof.
[0031] The core slots (not shown) that receive the respective
straight segments of the respective phase portions 30, 32, 34, 36,
38, and 40 may or may not be immediately adjacent each other,
discussed in more detail below. The end loop segments of the phase
portions 30, 32, 34, 36, 38, and 40 form a cascaded winding pattern
shown in FIG. 2. The cascaded winding pattern shown in FIG. 2 and
FIG. 3 also provides improved cooling for the stator winding 42 by
radially shifting a predetermined number of the phases 30, 32, 34,
36, 38, and 40 to provide increased cooling surface area. For
example in FIG. 2, the area between the phases 40 and 38 and
between the phases 30 and 32 is increased, which allows for more
air to flow between the phases, providing increased cooling.
[0032] A stator winding (not shown) with n number of phases (n=6 in
FIGS. 2 and 3), is considered to have zero shifted phases when the
phases are all disposed in a plurality of core slots 12 with the
phases beginning in consecutive n core slots 12, for example, the
first phase beginning in a slot number 1, the second phase
beginning in a slot number 2 immediately adjacent the slot number
1, the third phase beginning in a slot number 3 immediately
adjacent the slot number 2 and so forth including the nth phase
beginning in slot number n, immediately adjacent the slot number
n-1. For those skilled in the art it is known that the phases are
also considered in phase, and therefore not radially shifted, if
they are disposed in core slots 12 beginning in a slot positioned
C*n slots from its non shifted slot, where C is any even number
greater then equal to zero. For example, the first phase is
considered not radially shifted when it is positioned in the core
slots 12 beginning in slot number 1, C=0, or in slot number 13, C=2
or in slot number 25, C=4 and so forth. For a stator with radially
shifted phases, the radially shifted phases are disposed in the
core slots 12 beginning in a slot position B*n slots from its non
shifted slot, where B is any odd number greater then zero. For
example in FIG. 2, the phase 38 is disposed in the core slots 12
beginning in a slot number 8 which is radially shifted over 6 slots
(n=6, B=1) from its non shifted location beginning in slot number 2
and the phase 40 is disposed in the core slots 12 beginning in slot
number 10, which is radially shifted over 6 slots (n=6, B=1) from
its non shifted location beginning in slot number 4. For those
skilled in the art it is well known that these phases that are
considered radially shifted, are out of phase with its non-shifted
position by 180 electrical degrees.
[0033] Preferably, the stator winding 42 is formed in at least two
radial layers, which is schematically shown as a first layer
location 72 and a second layer location 74 in FIG. 1, which are
substantially identical to the layer 46 of FIG. 2. Preferably, the
layers 72 and 74 are radially spaced such that the straight
segments of the first layer 72 are located radially outward of the
straight segments of the second layer 74. The radial depth 25 of
each of the core slots 12 of the stator core 10 is adapted to
receive the at least two layers 72 and 74. Alternatively, the
radial depth 25 of each of the core slots 12 of the stator core 10
is adapted to receive more than two layers of the stator winding
42. Preferably, the circumferential length C1, including any
insulation (not shown), of each of the straight segments 44 of the
layers 72 and 74 is slightly less than the circumferential width
13, including any insulation (not shown), of the core slots 12,
best seen in FIG. 1.
[0034] The stator winding 42 is assembled according to the
following method: providing the generally rectangular conductors
for the stator winding 60; forming a layer of each of the phases
30, 32, 34, 36, 38, and 40 of the stator winding 42 to shape;
providing the stator core 10; sequentially inserting each of the
phases 30, 32, 34, 36, 38, and 40 for the outermost layer 72, in a
corresponding plurality of the core slots 12 of the stator core 10;
and repeating the steps for layer 74 and any additional desired
number of layers.
[0035] Each of the respective end loop segments 48, 46, 64, 66, 68,
and 70 of the phases 30, 32, 34, 36, 38, and 40 of the stator
winding 42 are cascaded, meaning that for each pass around the
stator core 10, each of the phases can be inserted into the stator
core 10 in a sequential order. For example, the sixth phase 40 is
inserted for one substantial revolution about the circumference 14
of the stator core 10. After the phase 40 is inserted, the phase 38
may be inserted for one substantial revolution about the
circumference 14 of the stator core 10. This pattern is repeated
for each of the phases 36, 34, 32, and 30. As seen in FIGS. 2 and
3, when the phases 30, 32, 34, 36, 38, and 40 are inserted in this
manner, the entire layer of each of the continuous layer of a
phases 30, 32, 34, 36, 38, and 40 may be wound about the
circumference 14 of the stator core 10 without interfering with any
of the other phases.
[0036] Referring now to FIG. 6, a dynamoelectric machine in
accordance with the present invention is indicated generally at
120. The dynamoelectric machine is preferably an alternator, but
those skilled in the art will appreciate that the dynamoelectric
machine can be, but is not limited to, an electric motor, an
integrated starter-motor, or the like. The dynamoelectric machine
120 includes a housing 122 having a shaft 124 rotatably supported
by the housing 122. A rotor assembly 126 is supported by and
adapted to rotate with the shaft 124. The rotor assembly can be,
but is not limited to, a "claw pole" rotor, a permanent magnet non
claw pole rotor, a permanent magnet claw pole rotor, a salient
field wound rotor or an induction type rotor. A stator assembly 128
is fixedly disposed in the housing 122 adjacent the rotor assembly
126. The stator assembly 128 includes a stator core, such as the
stator core 10 and winding with two radially aligned layers 72 and
74, wherein each layer is like such as the stator winding 42.
[0037] In accordance with the provisions of the patent statutes,
the present invention has been described in what is considered to
represent its preferred embodiment. However, it should be noted
that the invention can be practiced otherwise than as specifically
illustrated and described without departing from its spirit or
scope.
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