U.S. patent application number 12/009449 was filed with the patent office on 2008-05-22 for electric motor stator.
Invention is credited to Andrei Chugunov, Gary F. Glass, Stephen H. Purvines.
Application Number | 20080115345 12/009449 |
Document ID | / |
Family ID | 37056749 |
Filed Date | 2008-05-22 |
United States Patent
Application |
20080115345 |
Kind Code |
A1 |
Purvines; Stephen H. ; et
al. |
May 22, 2008 |
Electric motor stator
Abstract
Devices and methods are provided for a motor stator. One
embodiment for a stator includes a frame for stator windings that
includes a hub, spacing members, a rim and posts for receiving and
positioning windings of a stator coil. A thermoset material is
supplied to the stator to encapsulate the stator.
Inventors: |
Purvines; Stephen H.;
(Mishawaka, IN) ; Glass; Gary F.; (Wabash, IN)
; Chugunov; Andrei; (Ligonier, IN) |
Correspondence
Address: |
BROOKS, CAMERON & HUEBSCH , PLLC
1221 NICOLLET AVENUE , SUITE 500
MINNEAPOLIS
MN
55403
US
|
Family ID: |
37056749 |
Appl. No.: |
12/009449 |
Filed: |
January 18, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11156430 |
Jun 20, 2005 |
7345398 |
|
|
12009449 |
Jan 18, 2008 |
|
|
|
Current U.S.
Class: |
29/596 ; 29/598;
29/606; 29/857 |
Current CPC
Class: |
Y10T 29/49009 20150115;
Y10T 29/49073 20150115; Y10T 29/49174 20150115; Y10T 29/49012
20150115; H02K 3/47 20130101 |
Class at
Publication: |
029/596 ;
029/598; 029/606; 029/857 |
International
Class: |
H02K 15/02 20060101
H02K015/02; H02K 15/14 20060101 H02K015/14; H01F 7/06 20060101
H01F007/06; H01R 43/00 20060101 H01R043/00 |
Claims
1. A method of forming a frame for stator windings, comprising:
providing a first winding guide and a second winding guide on a hub
in a radially staggered configuration; providing a spacing member
that connects the hub to a rim; and providing a post on the
rim.
2. The method of claim 1, where providing a first winding guide and
a second winding guide includes providing walls that define a
curved surface having a first end and a second end for each of the
first winding guide and the second winding guide, and positioning
the first and second end of adjacent first winding guides between
the first and second end of the second winding guide.
3. The method of claim 2, including providing a ledge that extends
from both the first winding guide to the first and second end of
adjacent second winding guides, and the second winding guide to the
first and second end of adjacent first winding guides.
4. The method of claim 2, where providing the spacing member
includes positioning the spacing member to extend radially from a
position adjacent the first end and the second end of adjacent
first winding guides and adjacent second winding guides.
5. The method of claim 2, where the curved surface is concave
having a bottom relative the first end and the second end, where
the first end and second end of the first and second winding guides
are further away from a center axis of the hub than the bottom of
the curved surface.
6. The method according to claim 1, where forming the frame
includes coupling the rim to the spacing member, where the rim is
annularly positioned relative the hub.
7. The method according to claim 1, including providing a support
ledge on the rim, where the support ledge has two or more sections
each with surfaces defining wire guide channels that encircle the
hub.
8. The method of claim 1, where posts extend perpendicularly from
the rim.
9. A method of forming a stator, comprising: forming a frame that
includes: a hub having a first winding guide and a second winding
guide that are radially staggered relative each other by a
predetermined angle; a rim annularly positioned relative the hub;
posts on the rim; and providing windings of conductive wire around
at least a portion of the posts and adjacent the first winding
guide and the second winding guide of the hub forming coils of an
alternating current motor.
10. The method of claim 9, where forming the frame includes
positioning the posts on the rim where a predetermined portion of
each of the posts extends above and below the rim receiving the
windings of conductive wire.
11. The method of claim 10, where providing windings of conductive
wire includes extending windings of conductive wire around adjacent
posts above the rim and by the first winding guide; and extending
windings of conductive wire around adjacent posts below the rim and
by the second winding guide to form coils for the alternating
current motor.
12. The method of claim 11, where a first portion of the coils
share one of a first common radial plane and a second common radial
plane, and a second portion of the coils share a third common
radial plane that is different than the first and second common
radial planes.
13. The method of claim 9, where forming coils includes partially
containing a start lead segment and a finish lead segment within
the rim.
14. The method of claim 9, where forming the stator further
includes encapsulating the hub, the rim, the posts and windings of
conductive wire with a housing.
15. The method of claim 9, where forming the frame includes
providing spacing members that connect the hub to the rim.
16. A method of forming an electric motor, comprising: providing a
stator that includes: a hub including a rotor interface, a first
winding guide and a second winding guide, the first and second
winding guides positioned opposite the rotor interface and radially
staggered relative each other by a predetermined angle; a rim
annularly positioned relative the hub; posts positioned on the rim;
windings of conductive wire around at least a portion of the posts
and adjacent the first winding guide and the second winding guide
of the hub to form coils of the electric motor; and connector
terminals coupled to the windings for providing a potential through
the coils to operate the electric motor; fixing the stator within
an interior space of a motor enclosure; and positioning a rotor
adjacent the stator and rotatably coupled within the interior space
of the motor enclosure.
17. The method of claim 16, where providing the stator includes
providing a support ledge of the rim, where the support ledge has
two or more sections each having surfaces defining wire guide
channels that encircle the hub, and where each of the coils
includes a start lead segment and a finish lead segment at least
partially contained within the wire guide channels.
18. The method of claim 17, where providing the stator further
includes coupling the start lead segment and the finish lead
segment for each of the coils to the connector terminals for
operating the electric motor in one of a single phase configuration
and polyphase configuration.
19. The method of claim 16, where providing the stator includes
over-molding the hub, the rim, the posts and windings of conductive
wire, where the connector terminals extend from the
over-molding.
20. The method of claim 19, where the housing is a thermoset
material formed from a liquid resin thermoset precursor that is
selected from an unsaturated polyester, a polyurethane, an epoxy, a
phenolic, a silicone, an alkyd, an allylic, a vinyl ester, a furan,
a polyimide, a cyanate ester, a bismaleimide, a polybutadiene, and
a polyetheramide.
Description
PRIORITY INFORMATION
[0001] This application is a continuation of U.S. application Ser.
No. 11/156,430, filed Jun. 20, 2005, the specification of which is
incorporated herein by reference.
INTRODUCTION
[0002] Electrical induction motors include a stator and a rotor to
convert electrical energy into a magnetic interaction that causes
the rotor to turn. One aspect of creating this magnetic interaction
is found in the stator coils. Each stator coil includes windings of
conductive wire. When a potential is applied through the stator
coils an electromagnetic field can be generated. In addition to the
electromagnetic field, heat can also be generated due to the
electrical resistance of the conductive wire. The more efficiently
this heat can be dissipated, the more efficiently the motor can
run.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The Figs. presented herein provide illustrations of
non-limiting example embodiments of the present disclosure. The
Figs. are not necessarily to scale.
[0004] FIG. 1 illustrates one embodiment of a frame for an electric
motor stator according to the present disclosure.
[0005] FIG. 2 illustrates one embodiment of an electric motor
stator according to the present disclosure.
[0006] FIG. 3 illustrates one embodiment of an electric motor
stator with a housing according to the present disclosure.
[0007] FIG. 4 illustrates one embodiment of an electric motor
according to the present disclosure.
[0008] FIG. 5 illustrates one embodiment of a molding tool for over
molding a stator according to the present disclosure.
[0009] FIG. 6 illustrates one embodiment of a winding mandrel
according to the present disclosure.
[0010] FIG. 7 illustrates one embodiment of coils wound in series
according to the present disclosure.
[0011] FIG. 8 illustrates one embodiment of a frame for an electric
motor stator according to the present disclosure.
DETAILED DESCRIPTION
[0012] Embodiments of the present disclosure include electric
motors, components of electric motors (e.g., stators), and methods
associated therewith for improved electric motor operation and
manufacturing methods. It will be apparent to those skilled in the
art that the following description of the various embodiments of
this disclosure are provided for illustration only and not for the
purpose of limiting the disclosure as defined by the appended
claims and their equivalents.
[0013] As will be described herein, an electric motor includes,
among other things, a housing, a rotor, and a stator disposed
adjacent the rotor and fixed within the housing. In the embodiments
described in the present disclosure, the stator can be completely
encapsulated within a thermoset material. In some embodiments,
connector terminals, which form an electrical connection between
the stator and a power supply, extend from the completely
encapsulated stator. As used herein, a thermoset material includes
those polymeric materials that once shaped by heat and pressure so
as to form a cross-linked polymeric matrix are incapable of being
reprocessed by further application of heat and pressure.
[0014] As discussed herein, the stator is formed using a frame for
stator windings. The frame includes a hub having a rotor interface,
a first winding guide and a second winding guide, the first and
second winding guides opposite the rotor interface and radially
staggered relative each other by a predetermined angle. Spacing
members are coupled to and extend radially from the hub. A rim is
coupled to the spacing members and annularly positioned relative
the hub. Posts are positioned on the rim, where the posts, the
first winding guide and the second winding guide receive stator
windings of a conductive wire to form the coils of an electric
motor. The stator can then be encapsulated in the thermoset
material. As will be discussed herein, the thermoset material can
provide both mechanical stabilization and high thermal conductivity
properties to the stator.
[0015] Embodiments of the present disclosure include the stator in
a variety of electric motor configurations. For example, suitable
motor configurations can include motors that operate on alternating
current (AC) (i.e., induction or synchronous AC motor, switched
reluctance motor) and/or direct current (DC) (e.g., a universal
motor or a DC motor). As understood, AC motors can be configured as
a single-phase, split-phase, or poly-phase such as a three-phase
motor. Furthermore, it will be apparent to those skilled in the art
from this disclosure that although the present disclosure is used
with an electric motor, the present disclosure can be used with
other rotary type electric machines such as a generator or
motor/generator.
[0016] In addition, embodiments of the stator can be used in an
axial flux type electric motor. This motor is distinguished from
other electric motors due to the different path of the magnetic
flux. For example, in most alternating current electrical motors
the flux flows radially through the air gap between the rotor and
the stator. However in the axial flux type electric motor the flux
flows parallel to the axle of the motor. The rotor for the axial
flux type motor, often referred to as a pancake rotor, can be made
much thinner and lighter, hence these motors are often used for
applications requiring quick changes in speed.
[0017] In various embodiments of the present disclosure, the stator
includes coils mounted in the frame that holds the coils in the
appropriate relationship. In one embodiment, the coils can be
interlocked through the use of the frame. As will be discussed
herein, the frame for the stator windings forming the coils can be
formed of a single thermoplastic molded part that provides coil
mounting and locking features, wire guides, sensor board mounting,
coil insulation, and stator connector terminal integration. In one
embodiment, the frame can help to assure proper coil to coil
relationship, help in the incorporating of wire guides, features
for mounting the motor phase to phase sensor and thermal resistive
device mounting board, and coil to coil insulation. In various
embodiments, the frame and coils forming the stator are then
encapsulated within the thermoset material such that only the
connector terminals extend from the thermoset material.
[0018] The Figures herein follow a numbering convention in which
the first digit or digits correspond to the drawing figure number
and the remaining digits identify an element in the drawing.
Similar elements between different figures may be identified by the
use of similar digits. For example, 102 may reference element "02"
in FIG. 1, and a similar element "02" may be referenced as "202" in
FIG. 2. As will be appreciated, elements shown in the various
embodiments herein can be added, exchanged, and/or eliminated so as
to provide a number of additional embodiments.
[0019] In describing the various embodiments herein, the following
directional terms "annular," "axial," "circumferential," "radial,"
"longitudinal" and "transverse" as well as other similar
directional terms may be used. As used herein, these directional
terms as well as other directional terms refer to those directions
of the electric motor relative to a center rotational axis of a
rotor of the electric motor. Accordingly, these terms, as used to
describe the embodiments described herein should be interpreted
relative to the center rotational axis of the rotor of the electric
motor.
[0020] FIG. 1 illustrates one embodiment of a frame 100 for stator
windings according to an embodiment of the present disclosure. As
illustrated, the frame includes a hub 102. In various embodiments,
the hub 102 has a radial interior surface defining a rotor
interface 104. In one embodiment, the rotor interface 104 provides
a volume to receive at least part of a rotor.
[0021] The hub 102 also includes walls defining a first winding
guide 106 and a second winding guide 108. As illustrated, the first
and second winding guides 106, 108 are opposite the rotor interface
104 on the hub 102. The first and second winding guides 106, 108
are also radially staggered relative each other by a predetermined
angle 110. In one embodiment, the predetermined angle 110 can be
determined based on the number of winding guides 106, 108 on the
hub 102. As will be appreciated, the greater the number of winding
guides 106, 108 the smaller the predetermined angle, where as the
smaller the number of winding guides 106, 108 the greater the
predetermined angle. For example, as illustrated in FIG. 1 there
are nine (9) of the first winding guides 106 and nine (9) of the
second winding guides 108. In one embodiment, the winding guides
106, 108 are each of approximately equal dimensions and are equally
spaced in their radially staggered positions making the
predetermined angle twenty degrees (20.degree.).
[0022] The winding guides 106 and 108 generally provide walls
having a shape that can receive and help maintain the relative
position of windings of the coils provided in the frame 100. For
example, as illustrated the first and second winding guides 106,
108 include walls that define a curved surface 112 having a first
end 114 and a second end 116. The curved surface 112 can be concave
relative a central axis 118 of the hub 102 such that a bottom 120
of the curved surface 112 is closer to the central axis 118 as
compared to the first end 114 and second end 116 of the first and
second winding guides 106, 108, which are further away from the
center axis 118. As will be appreciated, other shapes besides a
curve are also possible. These can include walls defining planar
surfaces, concave surface, convex surfaces, and channeled
surfaces.
[0023] In one embodiment, the first and second end 114, 116 of
adjacent first winding guides 106 are positioned between the first
and second end 114, 116 of the second winding guide 108 to define
the predetermined angle 110. As illustrated, a radial surface 122
can be located between the first and second ends 114, 116 of
adjacent pairs of the first winding guides 106 and the second
winding guides 108.
[0024] In various embodiments, the frame 100 also includes a ledge
124. As illustrated, the ledge 124 extends from the surface 112 of
the first winding guide 106 to the first and second ends 114, 116
of adjacent second winding guides 108. The ledge 124 also extends
from the surface 112 of the second winding guide 108 to the first
and second ends 114, 116 of adjacent first winding guides 106. In
one embodiment, the ledge 124 can receive and help maintain the
relative position of windings of the coils provided in the frame
100.
[0025] The hub 102 can also include a positioning tab 126 to
receive and help maintain the relative position of windings of the
coils provided in the frame 100. As illustrated, the positioning
tab 126 provides a shelf like projection from the surface 112 of
the first and second winding guides 106, 108.
[0026] The frame 100 can further include spacing members 132
coupled to and extending radially from the hub 102. As illustrated,
the spacing members 132 extend radially from a position adjacent
the first end 114 and the second end 116 of adjacent first winding
guides 104 and adjacent second winding guides 106. The spacing
members 132 can have a rectangular cross-sectional shape, as
illustrated. Other cross-sectional shapes are also possible,
including but not limited to triangular, circular, oval, square,
and polygonal. In addition, the spacing members 132 can have a
uniform or a non-uniform cross-sectional size.
[0027] In one embodiment, the spacing members 132 extend between
and couple the hub 102 to a rim 134. As illustrated, the rim 134 is
annularly positioned relative the hub 102. The rim 134 can include
a support ledge 136 to receive and help maintain the relative
position of windings of the coils provided in the frame 100. As
illustrated, the support ledge 136 includes two or more sections
138 that extend radially away from the center axis 118. The
sections 138 can each include a planar surface 140 and a surface
defining wire guide channels 142 that encircle the hub 102. As
illustrated, the sections 138 alternate presenting the wire guide
channel 142 and the planar surface 140 as the support ledge 136
extends radially around the central axis 118.
[0028] In one embodiment, the wire guide channel 142 can receive
segments of conductive wire that connect the coils of the stator,
as will be discussed herein. As illustrated, the sections 138
alternate the presentation of the wire guide channel 142 around the
support ledge 136. This configuration can reduce any potential
movement of the segments of conductive wire once they are
positioned within the wire guide channel 142. In one embodiment, a
gap 144 is provided between adjacent sections 138 to allow the
segments of conductive wire to be wound into the wire guide channel
142.
[0029] In one embodiment, the wire guide channel 142 can include
one or more channels 146. As discussed, each channel can receive
segments of conductive wire that connect coils of the stator. As
will be appreciated, the number of channels 146 can depend on a
phase configuration of the motor in which the stator is to be used.
For example, in the embodiment illustrated in FIG. 1 there are
three channels 146, where each channel can receive segments of
conductive wire that operatively couple the coils of a common phase
in a three-phase motor. In an alternative embodiment, a single
channel 146 can be provided for the guide channel 142 for use in a
single phase motor.
[0030] The rim 134 further includes posts 150 positioned on the rim
134. As illustrated, the posts 150 are positioned adjacent to and
extend perpendicularly away from both the planar surface 138 and
the guide channel 142 surface of the support ledge 136. The posts
150 are positioned on an interior surface 152 of the support ledge
136 between two of the spacing members 132, where the adjacent
sections 138 extend radially away from the post 150. In one
embodiment, the posts 150 and the support ledge 136 can receive and
help maintain the relative position of windings of the coils
provided in the frame 100.
[0031] The post 150 can have a number of different shapes. For
example, as illustrated in FIG. 1 the post 150 can be configured as
an elongate tube having a bore 154. In one embodiment, the bore 154
is circular. Other shapes for the bore are also possible (e.g.,
oval, triangular). As will be appreciated, the tube can have a
number of cross-sectional shapes, such as those provided
herein.
[0032] Embodiments of the frame 100 can be formed using a number of
techniques and from a number of different materials. For example,
the frame 100 can be formed from of, by way of illustration and not
by limitation, thermoplastic and thermo-set polymers. Examples of
these polymers include polyolefins such as polyethylene and
polypropylene, polyesters such as Dacron, polyethylene
terephthalate and polybutylene terephthalate, vinyl halide polymers
such as polyvinyl chloride (PVC), polyvinylacetate such as ethyl
vinyl acetate (EVA), polyurethanes, polymethylmethacrylate,
pellethane, polyamides such as nylon 4, nylon 6, nylon 66, nylon
610, nylon 11, nylon 12 and polycaprolactam, polyaramids (e.g.,
KEVLAR), segmented poly(carbonate-urethane), Rayon, fluoropolymers
such as polytetrafluoroethylene (PTFE or TFE) or expanded
polytetrafluoroethylene (ePTFE), ethylene-chlorofluoroethylene
(ECTFE), fluorinated ethylene propylene (FEP),
polychlorotrifluoroethylene (PCTFE), polyvinylfluoride (PVF), or
polyvinylidenefluoride (PVDF). Examples of thermoset materials
include those discussed herein, besides other known thermosets.
[0033] In one embodiment, the frame 100 can be formed through an
injection molding process. For example, a single mold can be
configured to provide for shape of the frame 100, as discussed
herein. The thermoplastic material, or thermoset material, can be
injected into the mold to form the frame 100. In alternative
embodiment, the frame 100 could be formed in a casting process or
stamping. In alternative embodiment, segments of the frame 100 can
be individually formed and then coupled together to form the frame
100. For example, one or more of the hub 102, the spacing members
132 and/or the rim 134 can be individually formed. The individual
segments can then be coupled together to form the frame 100.
Examples of suitable techniques for coupling the individual
segments include use of chemical adhesives and/or thermal energy to
weld the individual segments together.
[0034] FIG. 2 illustrates an embodiment of a stator 260 that
includes the frame 200 and coils 262 formed from windings of
insulated conductive wire. As appreciated, the windings that form
coils 262 are from turns of one or more strands of the insulated
conductive wire. In one embodiment, the coil 262 can be positioned
around at least a portion of adjacent posts 250 and directly
adjacent to the ledge 224, tab 226 and one of the first winding
guide 206 or the second winding guide 208.
[0035] In addition, two or more of the coils 262 can be
electrically coupled in series in a single or polyphase
configuration. For example, in the present embodiment there is
shown a first series 264, a second series 266 and a third series
268 of coils 262 on the frame 200 that form a three-phase
configuration for the stator 260. As illustrated, adjacent coils
262 in each series 264, 266, 268 are positioned on opposite sides
of the frame 200. For example, a first coil 270 of the first series
264 can be positioned adjacent the first winding guide 206. A
second coil 272 of the first series 264 is then spaced apart from
the first coil 272, where the second coil 272 is positioned
adjacent to the second winding guide 208. A third coil 274 in the
first series 264 is likewise spaced apart from the second coil 272,
where the third coil 274 is positioned adjacent to the first
winding guide 206. This general pattern can then be repeated for
the coils 262 in the first, second, and third series 264, 266,
268.
[0036] In various embodiments, the coils 262 of the stator 260 are
positioned relative each other so as to allow for efficient use of
space. For example, the windings of adjacent coils 262 from the
second and third series 266, 268 can be positioned at least
partially within the volume defined by the windings of the first
series 264 of coils 262. This pattern can repeat itself for other
combinations of the windings for the first, second, and third
series 264, 266, 268. In one embodiment, this allows for a more
efficient use of space as the windings of the coils 262 can be more
tightly packed into the stator 260.
[0037] As illustrated, the windings of the coils 262 can extend
along two or more common radial planes. For example, the coils 262
can have a first portion 276 of the windings that share in either a
first common radial plane 278 or a second common radial plane 280.
The coils 262 also have a second portion 278 that shares a third
common radial plane 282 that is different than the first or second
common radial plane 278, 280. In one embodiment, the first portion
276 of the coils 262 can be located adjacent the rim 234, the ledge
242, and the first and second winding guides 206, 208. As
illustrated, coils 262 that are adjacent the first winding guide
206 share the first common radial plane 278, while the coils 262
that are adjacent the second winding guide 208 share the second
common radial plane 278.
[0038] The windings of the coils 262 also define a series of
corners. For example, the windings that form the coils 262 include
a first corner 280 and second corner 282 that bring the windings
around the adjacent posts 250. The windings also include a third
corner 284 that brings the windings around one of the first winding
guide 206 or second winding guide 208. In addition, the windings
also include bends 286 that allow the windings to transition
between either the first or second common radial plane 278, 280 and
the third common radial plane 282. In one embodiment, the bends 286
can be imparted to the coils 262 through the use of a machine press
process, as discussed herein.
[0039] The coils 262 of the stator 260 further include a start lead
segment 286 and a finish lead segment 288 that is at least
partially contained within the rim 234. In one embodiment, the
start lead segments 286 and the finish lead segments 288 of the
coils 262 for each of the first, second, and third series 264, 266,
268 are coupled in series. Each of the start lead segments 286 and
the finish lead segments 288 for the series of coils can then be
coupled to connector terminals 290 for operating the stator in one
of a single phase configuration and a polyphase configuration.
[0040] As illustrated, the stator 260 includes eighteen (18) coils
262 arranged annularly on the frame 200. In one embodiment, each of
the first, second, and third series 264, 266, 268 includes six (6)
coils 262 that are coupled in series and arranged as illustrated to
provide for a polyphase operation. As will be appreciated, the
stator 260 could be formed with other combinations and numbers of
coils 262.
[0041] Thus, the embodiment illustrated in FIG. 2 is not meant to
limit the present disclosure but rather to show one of many stators
that can be formed with the coils 262. For example, in some
embodiments, the stator 260 can include twelve (12) coils 262
annularly arranged on the frame 200.
[0042] The coils 262 can further include insulation positioned
between adjacent coils and the surface of the frame 200. For
example, the insulation can include a layer of insulating material
disposed on the windings of the coil 262. Examples of suitable
insulating material can include, but are not limited to,
Kapton.RTM. tape, NOMEX, MYLAR, TufQUIN, and the like.
[0043] As will be appreciated, the coils 262 can be formed from
windings of wires having one or more predetermined sizes of
American Wire Gauge (AWG), magnetic characteristics, malleability,
and number of turns. In addition, the wire can be formed from a
number of different electrically conductive metals (e.g., copper)
and/or metal alloys as are know. The wires forming the windings can
also be electrically insulated relative each other (e.g., each wire
has an electrically insulating sheath).
[0044] FIG. 3 illustrates an embodiment of a stator 360 for an
electric motor as described herein. As illustrated, the stator 360
includes a housing 392 that encapsulates the hub, the rim, the post
350 and windings of conductive wire that form the coils. The
housing 392 also defines an annular surface 394 adjacent the rotor
interface of the hub. In one embodiment, the connector terminals
390 of the stator 360, as discussed herein, extend from the housing
392.
[0045] In one embodiment, the bore 354 of the post 350 can receive
a mounting shaft to locate and secure the stator 360 in a motor
enclosure. The housing 392 can also include an alignment pin 356
that can be used to further locate the stator 360 in the motor
enclosure.
[0046] In one embodiment, the housing 392 is formed of a thermoset
material. As discussed herein, the thermoset material of the
housing 392 can be provided through an over molding process. As
used herein, a thermoset material includes those polymeric
materials that once shaped by heat and pressure so as to form a
cross-linked polymeric matrix are incapable of being reprocessed by
further application of heat and pressure. As provided herein,
thermoset materials can be formed from the polymerization and
cross-linking of a thermoset precursor. Such thermoset precursors
can include one or more liquid resin thermoset precursors. In one
embodiment, liquid resin thermoset precursors include those resins
in an A-stage of cure. Characteristics of resins in an A-stage of
cure include those having a viscosity of 1,000 to 500,000
centipoises measured at 77.degree. F. (Handbook of Plastics and
Elastomers, Editor Charles A. Harper, 1975).
[0047] In the embodiments described herein, the liquid resin
thermoset precursor can be selected from an unsaturated polyester,
a polyurethane, an epoxy, an epoxy vinyl ester, a phenolic, a
silicone, an alkyd, an allylic, a vinyl ester, a furan, a
polyimide, a cyanate ester, a bismaleimide, a polybutadiene, and a
polyetheramide. As will be appreciated, the thermoset precursor can
be formed into the thermoset material by a polymerization reaction
initiated by heat, pressure, catalysts, and/or ultraviolet
light.
[0048] As will be appreciated, the thermoset material used in the
embodiments of the present disclosure can include non-electrically
conducting reinforcement materials and/or additives such as
non-electrically conductive fillers, fibers, curing agents,
inhibitors, catalysts, and toughening agents (e.g., elastomers),
among others, to achieve a desirable combination of physical,
mechanical, and/or thermal properties.
[0049] Non-electrically conductive reinforcement materials can
include woven and/or nonwoven fibrous materials, particulate
materials, and high strength dielectric materials. Examples of
non-electrically conductive reinforcement materials can include,
but are not limited to, glass fibers, including glass fiber
variants, synthetic fibers, natural fibers, and ceramic fibers.
[0050] Non-electrically conductive fillers include materials added
to the matrix of the thermoset material to alter its physical,
mechanical, thermal, or electrical properties. Such fillers can
include, but are not limited to, non-electrically conductive
organic and inorganic materials, clays, silicates, mica, talcs,
asbestos, rubbers, fines, and paper, among others.
[0051] In an additional embodiment, the liquid resin thermoset
precursor can include a polymerizable material sold under the trade
designator "Luxolene" from the Kurz-Kasch Company of Dayton
Ohio.
[0052] FIG. 4 illustrates an embodiment of an electric motor 401
according to an embodiment of the present disclosure. As
illustrated, the electric motor 401 includes a motor enclosure 403,
the stator 460, as discussed herein, and a rotor 405. For ease of
illustration, other components of the electrical motor 401 are not
illustrated in FIG. 4, but those skilled in the art will understand
the components location and function in the design of an electric
motor.
[0053] In one embodiment, the motor enclosure 403 of the electric
motor 401 has an interior space sufficient to receive and house the
stator 460 and the rotor 405. The stator 460 can be fixedly
arranged within the interior space of the motor enclosure 403, with
the rotor 405 positioned adjacent the stator 460 and rotatably
coupled within the interior space of the motor enclosure 403. As
illustrated, the rotor 405 has a shaft 407 that extends past the
annular surface of the stator 460. The shaft 407 also supports
rotor discs 409 that are located at either side of the stator 460.
Each disc is made of a magnetically permeable material and has
either an inner face of electrically conductive material or an
inner face with conductive paths which can function as rotor
windings.
[0054] In one embodiment, the shaft 407 can be formed from a
non-magnetically permeable material. In this way the flux linkage
paths from one of the rotor discs to the other of the rotor discs
can be reduced and the magnetic paths are contained within the
discs and the stator poles. Fringing and losses may be reduced by
such a choice of shaft material. In one embodiment the shaft is
made from an austenitic stainless steel although other
non-magnetically permeable materials may also be used.
[0055] Methods and processes for forming the stator and various
components of the stator described herein are provided as
non-limiting examples of the present disclosure. As will be
appreciated, a variety of molding processes exist that can be used
to form the over molding component of the stator. Examples of such
molding processes can include resin transfer molding, compression
molding, transfer molding, and injection molding, among others. A
useful molding process can also be found in co-pending U.S.
application Ser. No. ______ entitled ______ assigned Delaware
Capital Formation and filed on ______, which is incorporated by
reference in its entirety.
[0056] FIG. 5 illustrates embodiments of a molding tool that can be
used in a molding process to form embodiments of the stator of the
present disclosure. The process for molding the stator can include
supplying a thermoset material to the molding tool such that when
the thermoset material is cured, it encapsulates the stator.
[0057] The following description provides an example of a process
for forming an over molded stator according to the teachings
described herein. In the following description, some structural
features are described, but not shown in the embodiments of FIG. 5.
Thus, where structural features are described, but not shown, the
description will refer to the embodiment illustrated in FIGS. 1 and
2.
[0058] As will be appreciated, the stator can be placed within a
molding tool and the thermoset material can be supplied to the
molding tool to encapsulate the stator. In one embodiment, the
thermoset material can be supplied to the molding tool to
completely encapsulate the stator, where the stator can be
positioned within the stator housing prior to being encapsulated
with the thermoset material.
[0059] FIG. 5 illustrates one example of a molding tool 515 for
encapsulating the stator according to an embodiment of the present
disclosure. In one embodiment, the molding tool 515 includes two
mold halves 517. Each mold half includes walls having surfaces that
defines a mold cavity volume 519 to receive the stator prior to
over molding. For example, the mold cavity 519 can include
circumferential walls 521 that are radially positioned to define
the volume to receive the stator, as illustrated in FIG. 2.
[0060] In one embodiment, the walls of the mold halves further
include channel extensions 523 that extend along a surface of the
mold halves 517 to receive the connector terminals of the stator,
as discussed above with respect to FIGS. 2 and 3. The channel
extensions 523 are sealably designed to receive the connector
terminals, which pass through to the exterior of the molding tool
515. The channel extensions 523 form a fluid and pressure tight
seal to prevent the thermoset material from discharging from the
molding tool 515 through the channel extensions 523 during the
molding process.
[0061] The molding tool 515 also includes a mold port 525 extending
through at least one of the mold halves 517. The molding port 525
provides the proper connections for supplying the thermoset
material to the interior of the molding tool 515 in the molding
process. The molding tool 515 also includes registration pins 527
that help to position both the stator within the molding tool 515
and align the mold halves 517. As will be appreciated, the molding
tool has registration sockets 529 that align with and receive the
registration pins 527 when the mold halves 517 close. In one
embodiment, the registration pins 527 within the mold cavity volume
519 can be received by one or more of the bores of the stator frame
posts.
[0062] As will be appreciated, the molding tool 515 can be also be
designed to include registers for a central pillar 531. The central
pillar 531 includes a cylindrical shape having outer surfaces 533
that help to define the annular surface of the stator when the
thermoset material is supplied to the molding tool 515. After the
central pillar 531 has been registered within the molding tool 515,
the molding tool 515 is closed to form a fluid and pressure tight
seal and a thermoset material can then be provided.
[0063] In one embodiment, the posts of the stator can also help to
position the frame and coils of the stator relative the walls
defining the mold cavity volume 519. For example, the posts can be
configured to extend beyond the first and second planar surfaces by
a predetermined distance. Similarly, the surfaces defining the mold
cavity can be configured to abut and apply compressive pressure to
the posts once the mold halves 517 are closed. In one embodiment,
the registration pins 527 and the surfaces of the mold cavity
volume 519 prevent the over molding material from filling the bores
of the posts. The pressure also helps to stabilize the stator
inside the mold cavity volume 519. Once the mold halves 517 have
closed on the stator, the posts position the coils and other
structures of the stator at predetermined distances from the
surfaces defining the mold cavity volume 519. These predetermined
distances in turn define the thicknesses of the housing that
encapsulates the stator.
[0064] In an additional embodiment, the surfaces defining the mold
cavity volume 519 also include stabilizing pins 535 on both the
mold halves 517. As illustrated, the stabilizing pins 535 extend
from the surface defining the mold cavity volume 519 in a region
that is adjacent the third planar surface of the coils. In one
embodiment, the stabilizing pins 535 can abut and hold the windings
of the coil under pressure to ensure that the coils do not move
during the molding process.
[0065] Providing the thermoset material can include injecting a
thermoset precursor (e.g., low-viscosity thermoset precursor) and
catalyst (optional) into the molding under low pressure to fill the
mold cavity volume 519 such that the thermoset material
encapsulates the stator, except the connector terminals, which
extend therefrom. Since the thermoset precursor can include a low
viscosity, the thermoset precursor can substantially fill spaces
defined by various surfaces of the stator, such as spaces between
and around insulated conductive wires, spaces within slots and
grooves, and spaces between the inner surface of the
circumferential wall and the coils of the stator, among other
spaces. Heat and pressure can then be applied to cure the thermoset
precursor to form the over molded stator. A post cure process can
also be used. After curing, the over molded stator can be removed
from the molding tool 515.
[0066] Encapsulating (e.g., completely encapsulating) the stator
within a thermoset material can provide for improved heat transfer
characteristics there from. For example, the thermoset material
encasing the insulated conductive wires serves to efficiently
conduct heat away from the wires and also to fill the gaps between
the wires where they extend from the ends of the stator sections.
In addition, the various portions of the stator can be tightly
secured together by complete encapsulation. For example, the
capsule serves to secure the insulated conductive wires to the
stator section to prevent movement of the wire. The thermoset
material also serves to secure the stator sections to each other to
help prevent the movement of the stator sections with respect to
each other. Such a feature can reduce the cost of the stator
because the stator does not require a stator ring, a common portion
of a stator in the prior art used to secure the annular sections to
each other.
[0067] FIG. 6 illustrates an embodiment of a winding mandrel 651
according to an embodiment of the present disclosure. In one
embodiment, the winding mandrel 651 allows for multiple coils to be
wound from contiguous lengths of wire. In one embodiment, winding
coils from a contiguous length of wire allows multiple coils to be
connected in series without the need for start or finish lead
segments of the coils to be electrically connected. As will be
appreciated, two or more coils in series can be formed using the
winding mandrel 651.
[0068] As illustrated, the winding mandrel 651 includes a winding
channel 653. In one embodiment, the winding channel 653 can receive
wire 655 for the windings of the coil. Wire 655 can be feed into
the winding channel 653 as the winding mandrel 651 is rotated 657.
As a coil is completed, the wire 655 can be extended to the
adjacent winding channel 653. The next coil in the series of coils
can then be wound.
[0069] In one embodiment, the winding mandrel 651 includes spacers
659 that determine a length of wire that extends between the
adjacent coils. The spacers 659 can be selected to provide a
predetermined length of wire between adjacent coils in the series.
As will be appreciated, the predetermined length of wire can be a
function of the configuration of coils around the stator frame.
[0070] The winding mandrel 651 can also include a pivot post 671
adjacent the winding channel 653. In one embodiment, the pivot post
671 provides a location around which the wire 655 upon completing a
coil can be turned and extended to the adjacent winding channel
653. In addition, the pivot post 671 can also provide a location to
secure the wire 655 adjacent the winding channel 653 prior to
beginning the winding process for the coil. The pivot post 671 can
also provide a guide so as to position the location of the
connecting segments of the wire 655 between the coils.
[0071] In one embodiment, the winding mandrel 651 can provide
winding channels 653 to produce up to six (6) coils in series. As
will be appreciated, more than six coils could be wound in series
if desired. In addition, the wires of the coils can also be bonded
in situ on the winding mandrel 651.
[0072] FIG. 7 provides an illustration of the coils 762 coupled in
series according to the methods discussed herein. The coils 762 can
then be bent so as to form the first and second portions 776, 778
of the coil, as discussed herein. In one embodiment, the first and
second portions 776, 778 can be formed by imparting bends 786 into
the coils 762.
[0073] In one embodiment, the bends 786 can be formed through the
use of a machine press operation. For example, the coils 762 can be
initially formed without the bends 786. In other words, the coils
762 are wound so as to have a common planar configuration. The
coils 762 can then be placed in plates having reliefs that define
the location and configuration of the bends to be imparted to the
coils 762. The plates are provided in the machine press. The coils
762 are then positioned within the plates. The machine press is
then used to press the plates together, thereby deforming the coils
762 so as to form the bends 786. As will be appreciated, other
processes for imparting the bends 786 are also possible, including
imparting the bends during the winding process itself.
[0074] While the present disclosure has been shown and described in
detail above, it will be clear to the person skilled in the art
that changes and modifications may be made without departing from
the spirit and scope of the disclosure. As such, that which is set
forth in the foregoing description and accompanying drawings is
offered by way of illustration only and not as a limitation. The
actual scope of the disclosure is intended to be defined by the
following claims, along with the full range of equivalents to which
such claims are entitled.
[0075] For example, FIG. 8 illustrates an embodiment of a frame 800
for stator windings according to an embodiment of the present
disclosure. As illustrated, the frame includes the hub 802, spacing
members 832, and the rim 834, as discussed herein. As illustrated,
the support ledge 836 of the rim 834 can include projections 875
defined by a wall that extends from the support ledge 836. The
projections 875 can help to receive and help maintain the relative
position of windings of the coils provided in the frame 800.
[0076] In one embodiment, the wall of the projections 875 can
extend parallel relative the central axis 818 either above or below
the support ledge 836. The direction of the projections 875 can
depend upon the side of the support ledge 836 that is to receive
the coil. As will be appreciated, one or more of the support ledges
836 can have projections 875. FIG. 8 also illustrates an embodiment
in which the spacing members 832 and the rim 834 can also include
channels 877, notches 879, and/or ridges 881 for receiving various
components (e.g., the coil) of the stator. In addition, FIG. 8
provides an illustration in which the spacing members 832 include a
tapered segment 883 relative the remaining segment of the spacing
members 832.
[0077] In addition, one of ordinary skill in the art will
appreciate upon reading and understanding this disclosure that
other variations for the disclosure described herein can be
included within the scope of the present disclosure.
* * * * *