U.S. patent application number 16/688445 was filed with the patent office on 2020-04-02 for electrical machine and method of manufacture.
The applicant listed for this patent is Ingersoll-Rand Company. Invention is credited to Petri Juhani Maki-Ontto, Juha Tuomas Saari.
Application Number | 20200106313 16/688445 |
Document ID | / |
Family ID | 1000004500435 |
Filed Date | 2020-04-02 |
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United States Patent
Application |
20200106313 |
Kind Code |
A1 |
Saari; Juha Tuomas ; et
al. |
April 2, 2020 |
ELECTRICAL MACHINE AND METHOD OF MANUFACTURE
Abstract
An electrical rotor machine and a method of manufacturing the
same are disclosed. According to at least one aspect of the present
disclosure, the method includes forming a stator core from two or
more subcores and inserting the separate subcores into a housing
before windings are wound through and around the subcores to form a
stator. In such embodiments, the housing includes a locating
feature structured to position and support the subcores such that a
flow channel is formed between the subcores. The locating feature
enables both radial and axial cooling of the stator core while
reducing pressure losses within the cooling flow path.
Inventors: |
Saari; Juha Tuomas; (Espoo,
FI) ; Maki-Ontto; Petri Juhani; (Espoo, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ingersoll-Rand Company |
Davidson |
NC |
US |
|
|
Family ID: |
1000004500435 |
Appl. No.: |
16/688445 |
Filed: |
November 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14964125 |
Dec 9, 2015 |
10483812 |
|
|
16688445 |
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62099064 |
Dec 31, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 15/024 20130101;
H02K 15/085 20130101; H02K 9/04 20130101; H02K 1/185 20130101; H02K
1/20 20130101 |
International
Class: |
H02K 1/20 20060101
H02K001/20; H02K 15/02 20060101 H02K015/02; H02K 1/18 20060101
H02K001/18; H02K 9/04 20060101 H02K009/04 |
Claims
1. A method of manufacturing an electrical machine, the method
comprising: fabricating two or more subcores, the subcores
including a plurality of winding channels along an axial length of
each subcore, the winding channels structured to receive stator
windings; fabricating a housing having a wall defining a volume,
the housing structured to support the subcores within the volume,
the housing further including an aperture through the wall and a
locating feature structured to position the subcores; inserting
each subcore into the volume of the housing, wherein the subcores
seat against opposing sides of the locating feature, whereby a flow
channel is formed between the subcores, the flow channel aligned
and in communication with at least one of the aperture of the
housing; and installing the stator windings in the winding channels
of the subcores to form a stator within the housing, whereby the
stator windings extend through the winding channels of adjacent
subcores.
2. The method of claim 1, the method further comprising inserting a
rotor and shaft assembly into the housing within the stator.
3. The method of claim 1, wherein the aperture and the flow channel
form a cooling path through the stator, the cooling path configured
to enable a coolant to flow between the subcores and over the
stator windings, wherein the locating feature is positioned outside
the cooling path.
4. The method of claim 3, wherein the cooling path is substantially
perpendicular to a longitudinal axis of the machine.
5. The method of claim 1, wherein the subcores are shrink-fit to
the housing.
6. The method of claim 1, wherein the subcores are fastened to the
housing by a mechanical fastener or an adhesive.
7. The method of claim 1, wherein the stator comprises two subcores
positioned by the locating feature therebetween.
8. The method of claim 1, wherein the housing comprises a plurality
of apertures circumferential spaced about the wall and comprises a
plurality of locating features positioned between the
apertures.
9. The method of claim 1, wherein the locating feature is
fabricated separately from the housing and attached thereto.
10. A method of manufacturing an electrical rotor machine, the
method comprising: fabricating a plurality of stator laminations,
each lamination including a plurality of slots; manufacturing at
least two subcores by assembling a prescribed portion of the
plurality of laminations to form each subcore, wherein the
plurality of slots of the laminations are aligned to form a
plurality of winding channels through each subcore along a
longitudinal axis, the winding channels structured to receive
stator windings; fabricating a housing defining a cavity, the
housing structured to support the subcores within the cavity and
including a plurality of apertures formed therethrough to enable a
flow of a coolant into the cavity, wherein the housing further
includes a feature structured to locate the subcores within the
cavity, wherein the feature is disposed within the cavity between
the apertures; inserting each subcore into the housing such that
the subcores are separated by the feature of the housing to form a
flow channel between each subcore, the flow channel in fluid
communication with at least one of the apertures of the housing;
installing the stator windings in the winding channels of the
subcores to form a stator within the housing, whereby the stator
windings extend through the winding channels of adjacent subcores;
and inserting a rotor and shaft assembly into the housing within
the stator.
11. The method of claim 10, wherein the apertures and the flow
channel form a cooling path through the stator, the cooling path
configured to enable a coolant to flow between the subcores and
over the stator windings, wherein the feature of the housing is
positioned outside the cooling path.
12-16. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/099,064, filed Dec. 31, 2014, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure generally relates to electrical
machines and, more specifically, to electrical rotor machines and
manufacture of the same.
BACKGROUND
[0003] Electrical machines, including, for example, electric motors
and generators, generate heat that is often associated with
electrical and mechanical losses within the machines. In rotating
electrical machines losses are particularly high during starting or
dynamic braking. The amount of heat generated by a particular
electrical machine may depend on a variety of different factors,
including, for example, the magnitude of the load on the electrical
machine and the frequency of the starting and braking of the
electrical machine, among other factors. Cooling of electrical
machines is often necessary to continuously transfer the heat from
the machine to mitigate a variety of heat-induced problems that may
hinder the operation and/or shorten the life span of electrical
machines, including short circuits and winding burnout and failure,
among other heat related issues.
[0004] Cooling of electrical machines often involves transferring
the heat generated by the machine to a cooling medium, such as air,
for example. Conventionally, electrical machines are cooled
externally from the outer surface of the housing enclosing the
operational components of the machine, often by one or more fans
mounted on the shaft of the machine. To allow for operation of the
machine in either direction of rotation, the fans are usually of
the bi-directional type and made of a strong plastic, aluminum, or
steel material. However, such cooling methods require that the heat
be conducted from the windings through the core yoke, core/housing
shrink fit, and the wall of the housing. In certain machines, this
heat flow path is not adequate to prevent overheating because the
heat flux generated within the machine is too great to be removed
via conduction through the cross-sectional area of the available
heat flow path. Alternatively, the cooling medium may be flowed
through the machine. However, such a cooling scheme requires power
to generate an adequate cooling flow, which lowers the efficiency
of the electrical machine. Moreover, such a cooling scheme requires
cooling flow paths be formed through the machine, which inevitably
include pressure losses and increase the complexity and cost of
manufacturing the electrical machines. Accordingly, there remains a
need for further contributions in this area of technology.
SUMMARY
[0005] An electrical rotor machine and a method of manufacturing
the same are disclosed. According to at least one aspect of the
present disclosure, the method includes forming a stator core from
two or more subcores and inserting the separate subcores into a
housing before windings are wound through and around the subcores
to form a stator. In such embodiments, the housing includes a
locating feature structured to position and support the subcores
such that a cooling channel is formed between the subcores. The
locating feature enables both radial and axial cooling of the
stator core while reducing pressure losses within the cooling flow
path. This summary is provided to introduce a selection of concepts
that are further described herein in the illustrative embodiments.
This summary is not intended to identify key or essential features
of the claimed subject matter, nor is it intended to be used as an
aid in limiting the scope of the claimed subject matter. Further
embodiments, forms, objects, features, advantages, aspects, and
benefits shall become apparent from the following description and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0007] FIG. 1 is a cross-sectional view of a portion of an
electrical rotor machine according to the present disclosure;
[0008] FIG. 2 is a front view of a lamination of an electrical
rotor machine according to the present disclosure;
[0009] FIG. 3 is a plan view of an electrical rotor machine
according to the present disclosure; and
[0010] FIG. 4 is a schematic flow diagram of a method of
manufacturing an electrical rotor machine according to the present
disclosure.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0011] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended, any alterations and further modifications in the
illustrated embodiments, and any further applications of the
principles of the invention as illustrated therein as would
normally occur to one skilled in the art to which the invention
relates are contemplated herein.
[0012] The present application discloses various embodiments of an
electrical rotor machine and methods for using and constructing the
same. According to one aspect of the present disclosure, the method
includes forming a stator core from two or more subcores and
inserting the separate subcores into a housing before windings are
wound through and around the subcores to form a stator. In such
embodiments, the housing includes a locating feature structured to
position and support the subcores such that a cooling channel is
formed between the subcores. The locating feature enables both
radial and axial cooling of the stator while reducing pressure
losses within the cooling flow path, thereby improving the
operating range and efficiency of the electrical rotor machine.
[0013] An electrical rotor machine 100 including a cooling system
40 is shown in FIG. 1 according to at least one embodiment of the
present disclosure. The illustration of FIG. 1 depicts a
cross-sectional view of a portion of the machine 100, specifically
a central portion about a central longitudinal axis 16 of the
machine 100. In at least one embodiment, the machine 100 is
substantially symmetric about the axis 16. As shown in FIG. 1, the
machine 100 may include a housing 10 having a housing wall 11
generally defining a cavity 12 therein. The housing 10 is
configured to house components of the machine 100. In certain
embodiments, the housing 10 may be a yoke for the machine 100,
providing both mechanical support and carrying magnetic flux
generated by the machine 100 in operation. The cavity 12 may have
any suitable shape and configuration, including, as one
non-limiting example, a generally cylindrical shape defined by the
wall 11 of the housing 10, which may be substantially cylindrically
shaped. The machine 100 may further include a rotor/shaft assembly
14 disposed at least partially within the cavity 12 along the axis
16. The rotor/shaft assembly 14 may include a rotatable shaft
operably mounted to a rotor such that the rotor/shaft assembly 14
rotates about the axis 16. The rotor/shaft assembly 14 may be a
conventional assembly of a rotor and shaft for an electrical rotor
motor configured to operate with other components and aspects of
the machine 100. The machine 100 may further include a stator 20
disposed within the cavity 12 and surrounding the rotor/shaft
assembly 14 as described further herein.
[0014] The electrical rotor machine 100 may be one of a variety of
different types of electrical motors and generators, including, but
not limited to, induction motors. Further, the machine 100 may have
a variety of operating parameters and characteristics. For example,
according to certain embodiments, the machine 100 may be a high
speed induction motor, which may operate at a variety of different
speeds, including, for example, at speeds in excess of 7,200
revolutions per minute (rpm), 15,000 rpm, or 30,000 rpm. Further,
for example, according to certain embodiments, the machine 100 may
be a relatively low voltage induction motor, such as, for example,
an induction motor that may be wound for voltages from around 400
volts to around 700 volts, among other voltages. In alternative
embodiments, the machine 100 may operate at speeds and voltages
outside of the exemplary ranges provided.
[0015] As illustrated in FIG. 1, the stator 20 may include two or
more subcores 22, which may be supported or otherwise secured
within the cavity 12 of the housing 10. Though the stator 20 may
include more than two separate subcores 22, two subcores 22a, 22b
are depicted. Each subcore 22 may be formed of a plurality of
laminations 24 that are stacked and bonded together to form the
subcore 22. FIG. 2 shows a front view of a lamination 24 comprising
a subcore 22. The laminations 24, and the composite subcores 22,
may be any suitable shape. In embodiments where the cavity 12 of
the housing 10 has a generally cylindrical shape, the laminations
24 may be substantially circular in front view as shown in FIG. 2,
as may be the composite subcores 22. The laminations 24 and
subcores 22 may be made of any suitable electromagnetic material
such as steel plate, for example. In alternative embodiments,
instead of an assembly of separate laminations 24, each subcore 22
may be manufactured as an integral, solid part having the features
shown in FIG. 2 as described further herein. Further, in certain
embodiments, the subcores 22 may be operably connected to at least
one magnet.
[0016] The individual subcores 22 may be positioned and supported
within the cavity 12 by at least one locating feature 18 of the
housing 10. The locating feature 18 may be a tab, boss, rib, knob,
or other suitable protrusion from an interior surface of the wall
11 of the housing 10 capable of positioning and supporting each
subcore 22 and maintaining the relative positions of each subcore
22 to one another. The particular form of the locating feature 18
may vary between embodiments of present disclosure. Regardless of
specific form, the locating feature 18 extends into the cavity 12
and enables each subcore 22 to seat within the housing 10 such that
the subcores 22 are spaced apart from one another at a fixed
distance. In certain embodiments, the locating feature 18 may be
formed as an integral part of the housing 10. In such embodiments,
the locating feature 18 may be machined into the housing 10 by any
appropriate method. Alternatively, the locating feature may be
manufactured separately from the housing 10 and attached to the
housing 10. In such embodiments, the locating feature 18 may be
shrink-fit, press-fit, welded, fastened, or attached by any
suitable means.
[0017] The stator 20 may further include a plurality of stator
windings 30 extending axially between and around each subcore 22 as
shown in FIG. 1. The stator windings 30 may be disposed within
winding channels 32 formed through each subcore 22. As shown in
FIG. 2, each lamination 24 includes a plurality of the winding
grooves 34 formed therethrough and distributed circumferentially
around a central opening 36 through the lamination 24, such that
each winding groove 34 is in communication with the opening 36. The
opening 36 may be formed substantially about a centroid of the
lamination 24. In assembly, the winding grooves 34 of the
individual laminations 24 are aligned and combine to form a
plurality of winding channels 32 through which the windings 30 are
wound. Accordingly, the winding channels 32 of adjacent subcores 22
may further be aligned as shown in FIG. 1, such that the windings
30 may extend axially between the corresponding winding channels 32
of the subcores 22 in a straight line.
[0018] The windings 30 may be made of a plurality of strands of a
conductive material drawn into a wire. As non-limiting examples,
the windings 30 may be copper, carbon, silver, aluminum, or alloys
thereof. Though depicted as a solid mass in FIGS. 1 and 3, the
windings 30 may be formed by looping multiple strands of the wire
through the winding channels 32 of adjacent subcores 22 and around
opposite ends of the subcores 22 and by continuing the looping
process around the periphery of the opening 36. Each loop of the
strands forming the winding 30 is commonly referred to as a turn.
During assembly, a predetermined number of strands may be looped
through the winding channels 32 to form the windings 30. In
operation, the windings 30 carry electric current to generate an
electromagnetic field. Significant heat may be generated in the
windings 30 during operation due to the flow of electric current,
and that heat may be conducted into the subcores 22, housing 10,
rotor/shaft assembly 14, and other components of the machine 100.
The heat generated in the windings 30, and by electrical and
mechanical losses in the machine 100, must be dissipated to prevent
excessive temperatures and overheating, which may damage the
machine 100.
[0019] Referring to FIG. 1, the machine 100 may further include a
cooling system 40 having both radial and axial aspects. In at least
one embodiment according to the present disclosure, the cooling
system 40 may include a radial coolant path 50, an inner axial
coolant path 52, and an outer axial coolant path 54 for routing a
flow of the coolant through the machine 100. In certain
embodiments, the cooling system 40 may include a plurality of axial
coolant paths. The coolant may be air such as, for example, ambient
air or cooled air. Alternatively, the coolant may be any suitable
gas, such as pure nitrogen, compatible with the electrical
components and operation of the machine 100.
[0020] FIG. 3 shows a plan view of the machine 100 in which the
rotor/shaft assembly 14 is not shown for clarity. The cooling
system 40 may include a plurality circumferentially spaced radial
channels 42 distributed about the rotor/shaft assembly 14. FIG. 1
illustrates one such radial channel 42. The radial channels 42 are
at least partially defined by the space between the subcores 22
(e.g., the subcores 22a, 22b of FIG. 1). The radial channels 42 are
further defined by circumferentially spaced housing inlets 41
formed through the wall 11 of the housing 12. The housing inlets 41
and the radial channels 42 enable a flow of coolant from outside of
the housing 10, through the housing inlets 41, into the cavity 12,
and between the subcores 22, thereby drawing heat from the subcores
22 and windings 30. The housing inlets 41 may be circumferentially
spaced such that at least one locating feature 18 may be positioned
between each housing inlet 41. Alternatively, the housing 10 may
include fewer than one locating feature 18 between each housing
inlet 41. Regardless, the locating features 18 does not interfere
with or block the flow of coolant through the radial channels 42.
The cross-section of FIG. 1 illustrates one housing inlet 41 and
locating feature 18. For clarity, the housing inlet 41 has been
depicted in hidden line through the wall 11 to indicate that the
inlet 41 is not in the same plane as the locating feature 18, which
is depicted in solid line.
[0021] The radial channels 42 may be generally oriented
perpendicular to the longitudinal axis 16 of the machine 100.
However, the radial channels 42 may include other configurations
and orientations. According to certain embodiments, the radial
channels 42 may be located at approximately a central or midpoint
location along an axial length of the stator 20, the axial length
being generally in a direction that is parallel to the longitudinal
axis 16. More specifically, referring to FIGS. 1 and 3, the radial
channels 42 may be configured such that the subcores 22a, 22b on
opposing sides of the radial channels 42 are generally symmetrical
and/or have approximately equal axial lengths.
[0022] As shown in FIGS. 1-3, the windings 30, being looped through
the winding channels 32 of the subcores 22, are bundled such that a
winding gap 38 may be formed between each winding bundle. The
winding gap 38 enables the flow of coolant to run around and past
each winding bundle and to proceed to the rotor/shaft assembly 14
within the aperture 36 of the subcores 22. Accordingly, in FIG. 1,
the radial coolant path 50 is depicted as extending from outside
the housing 10, over the windings 30, and to the rotor/shaft
assembly 14. Thus, the radial channels 42 enable the radial coolant
path 50, which draws heat from both the subcores 22 and the
windings 30, heat that is generated during operation of the machine
100. Further, the radial coolant path 50 is in fluid communication
with the inner axial coolant path 52 and the outer axial coolant
path 54, thereby supplying the inner and outer axial coolant paths
52, 54 with coolant.
[0023] Referring to FIG. 1, the cooling system 40 may include the
inner axial coolant path 52. The inner axial coolant path 52 may
extend from the radial channel 42, where the radial coolant path 50
impinges upon the rotor/shaft assembly 14, and through a rotor gap
44 between the stator 20 (i.e., the subcores 22) and the
rotor/shaft assembly 14. The rotor gap 44, which in FIG. 1 is
exaggerated in size for clarity, provides a clearance between the
stationary stator 20 and the rotating rotor/shaft assembly 14 to
enable rotation of the rotor/shaft assembly 14 relative to the
stator 20. Moreover, the rotor gap 44 enables the inner axial
coolant path 52 to extend from the radial channel 42 to each axial
end of the stator 20, thereby enabling the coolant to draw heat
from the rotor/shaft assembly 14 and innermost portions of the
stator 20.
[0024] The cooling system 40 may further include the outer axial
coolant path 54. In certain embodiments, the cooling system 40 may
include a plurality of outer axial coolant paths 54. As shown in
FIG. 2, each lamination 24 may include a plurality of apertures 28
formed therethrough. Though depicted as circular in FIG. 2, the
apertures 28 may have a variety of suitable shapes, configurations,
arrangements, and orientations. In embodiments, where the
individual laminations 24 are stacked and bonded together to form
the subcore 22, the apertures 28 combine to form a plurality of
stator ducts 46 extending between opposing ends of each subcore 22.
Two such stator ducts 46 are shown in FIG. 1, one in each subcore
22. In embodiments where the apertures 28 are circular, the
composite stator duct 46 may be a generally cylindrically shaped
passage extending axially parallel to the longitudinal axis 16.
Further, the axial lengths of the stator ducts 46 may be
substantially the same. In such an embodiment, the stator ducts 46
extend from the radial channels 42 to the opposite axial end of the
subcores 22. Accordingly, each stator duct 46 may include a duct
inlet 47 adjacent the radial channel 42 and an opposing duct outlet
48 at the terminus of the duct 46.
[0025] In at least one embodiment, the plurality of apertures 28
may be arranged in concentric rings having different radii from a
centroid of each lamination 24. As shown in FIG. 2, the plurality
of apertures 28 may be arranged in a first set 28a and a second set
28b in which the first set 28a is offset or staggered relative to
the second set 28b such that the apertures 28 of the first set 28a
are not radially in line with the apertures 28 of the second set
28b. Consequently, the plurality of stator ducts 46 (not shown in
FIG. 2), formed from the assembly of the laminations 24 having the
apertures 28, may be similarly arranged in staggered concentric
sets. Alternatively, the apertures 28 and composite stator ducts 46
may be arranged in any suitable configuration that enables a
desired heat transfer while maintaining sufficient structural
strength in the subcores 22 to withstand the mechanical and thermal
stresses of the machine 100 in operation. Further, according to
certain embodiments, the apertures 28 and composite stator ducts 46
may be configured, sized, and/or shaped to enable the desired heat
transfer.
[0026] The plurality of stator ducts 46 enable the outer axial
cooling path 54 to extend from the radial channel 42 to the
opposing ends of each subcore 22. Accordingly, the outer axial
cooling path 54 may include a plurality of paths, one through each
stator duct 46. The duct inlet 47 and duct outlet 48 of each stator
duct 46 may be configured in size and shape to control the rate of
coolant flow through a given stator duct 46. In certain
embodiments, the duct inlets 47 and duct outlets 48 may be
configured to generate turbulence in the flow of coolant, which may
increase the rate of heat transfer thereto. According to certain
embodiments, each subcore 22 may be capped by a pair of end plates
(not shown), the end plates including the duct inlets 47 and duct
outlets 48. The end plates may have a shape generally similar or
corresponding to the laminations 24 and may be constructed from a
non-magnetic material so as to minimize iron losses. The end plates
enable the size, shape, and configuration of the duct inlets 47 and
duct outlets 48 of each subcore 22 to be different than the
apertures 28, thereby enabling flexibility in the configurations of
the duct inlets 47 and duct outlets 48.
[0027] The cooling system 40 may be configured to control the
relative quantities of coolant supplied from the radial channel 42
to cool the stator 20 through the stator ducts 46 (i.e., the outer
axial coolant path 54) and, thereby the amount of coolant that
flows into the rotor gap 44 between the stator 20 and the
rotor/shaft assembly 16 (i.e., the inner axial coolant path 52).
Such division of the coolant may be based on operating
characteristics of the machine 100, including, for example, the
anticipated pressure losses between the stator 20 and rotor/shaft
assembly 16, as well as losses attributable to flow friction. For
example, according to certain embodiments, the amount of coolant
desired to flow through the inner axial coolant path 52 may be
increased by a decrease in the size and/or number of stator ducts
46 in the subcores 22, which restricts flow through the outer axial
coolant path 54.
[0028] The cooling system 40 enables convective cooling of the
machine 100. Specifically, the radial coolant path 50 enables the
introduction of the coolant into the machine 100 between the
subcores 22 and over at least a portion of the windings 30. The
flow of coolant along the radial coolant path 50 facilitates
convective heat transfer from the relatively subcores 22 and
windings 30 to the relative cool coolant. Because the radial
coolant path 50 is in fluid communication with the inner and outer
axial coolant paths 52, 54, the flow of coolant along the radial
coolant path 50 may continue via the inner and outer axial coolant
paths 52, 54, thereby drawing additional heat from the relatively
hot subcores 22 and windings 30. Further, as the coolant flow from
the inner and outer axial coolant paths 52, 54 exits the stator 20
via the duct outlets 48, the coolant may flow over the loops of the
windings 30 that extend beyond the subcores 22, further
facilitating heat transfer directly from the windings 30. Upon
exiting the stator 20, the coolant may exit the cavity 12 of the
housing 10 through vents, seams, gaps, and/or other flow path (not
shown) from the cavity 12 to the environment.
[0029] In at least one embodiment, the cooling system 40 may
include a fan 56 to push and/or pull the coolant through the radial
coolant path 50, inner axial coolant path 52, and outer axial
coolant path 54 to enable forced convection. Forced convection
increases the rate of heat transfer between the coolant and the
machine 100, and the rate of heat transfer is proportional to the
rate of flow of the coolant through the cooling system 40. The fan
56 may be any suitable flow generation device, for example a
blower, bellows, or pressure reservoir, capable of generating a
flow of the coolant. In certain embodiments, the fan 56 may be
located remotely from the machine 100 and connected in fluid
communication to the housing inlet 41 via a conduit 58 as shown in
FIG. 1. In certain embodiments, the fan 56 may recirculate the
coolant. In such an embodiment, the cooling system 40 may include
conduits to accept the flow of coolant from the cavity 12 and route
the same back through the fan 56. Such embodiments may further
include additional components to actively cool the coolant
returning from the cavity 12. Such components may include a
refrigeration system.
[0030] Pressure losses within the cooling system 40 may tend to
lower the power efficiency of the machine 100. Pressure losses
increase the pressure difference required to generate sufficient
flow of coolant through the coolant system 40, which further
requires increased power input to the fan 56, in such embodiments,
or decreased output from the machine 100 to limit temperature rise.
Pressure losses result from friction between the flow of coolant
and the various channels, ducts, and gaps through which the radial
coolant path 50, outer axial coolant path 54, and inner axial
coolant path 52 proceed. Further pressure losses result from
changes in flow area along each of the coolant paths 50, 52, 54.
Moreover, pressure losses may result from obstructions in the
coolant paths 50, 52, 54 that decrease the effective flow area, at
least locally. Consequently, the power required to adequately cool
the machine 100 is dependent upon the pressure losses in the
cooling system 40. Accordingly, reduction of such pressure losses
increases the overall power efficiency of the machine 100.
[0031] Conventional electric motors that have radial cooling
channels use supports between the subcores to position and assembly
the subcores together. These supports are obstructions in the
cooling channel that increase pressure losses and lower the
efficiency of the conventional electric motor. In contrast, the
machine 100 does not include assembly supports in the radial
channels 42. The machine 100 employs the locating feature 18 in the
housing 10 to position and support the individual subcores 22
within the cavity 12. As described herein, the locating features 18
may be circumferentially spaced and positioned between the housing
inlets 41 such that the locating features 18 do not interfere with
or block the flow of coolant through the radial channel 42.
Consequently, the machine 100 has lower pressure losses and higher
overall power efficiency than conventional electric motors.
[0032] The degree to which the locating feature 18 extends into the
cavity 12 is limited to further minimize pressure losses.
Specifically, the locating feature 18 extends no further than an
outer edge of an outermost stator duct 46 and, thus, does not
disrupt the flow of coolant through any stator duct 46. Because the
locating features 18 are positioned between the housing inlets 41
and do not extend across the stator ducts 46, the locating features
18 have minimal contribution to pressure losses in the cooling
system 40. Moreover, the limited size of the locating features 18
increases the effective flow area of the radial coolant path 50.
Once the coolant flows through the housing inlets 41 and past the
locating features 18, the once separate radial channels 42 merge
into a shared volume between the subcores 22, the shared volume
having an effective flow area defined by the unobstructed region
between the subcores 22. Therefore, the locating features 18 are
positioned and sized to enable the unobstructed radial coolant path
50, which reduces pressure losses relative to conventional electric
motors.
[0033] To adequately position and retain the individual subcores 22
within the housing 10 without conventional supports, the machine
100 employs a novel method of manufacture. The schematic flow
description that follows provides an illustrative embodiment of a
method of manufacturing the machine 100. Operations illustrated are
understood to be exemplary only, and the operations may be combined
or divided, and added or removed, as well as re-ordered in whole or
part, unless stated explicitly to the contrary herein. Certain
operations illustrated may be implemented by a computer executing a
computer program product on a non-transient computer readable
storage medium, where the computer program product comprises
instructions causing the computer to execute one or more of the
operations, or to issue commands to other devices to execute one or
more of the operations.
[0034] As shown in FIG. 4, a method 200 of manufacturing the
machine 100 may include an operation 210 of manufacturing the
laminations 24. The laminations 24 may be cut or stamped from steel
plate or other suitable material. Alternatively, the laminations 24
may be cast. The operation 210 may include processes such as
deburring or post-fabrication machining. The method 200 may include
an operation 220 of assembling the laminations 24 into at least two
subcores 22. The laminations 24 may be assembled by conventional
methods known in the art. The method 200 may further include an
operation 230 of manufacturing the housing 10 such that the housing
10 includes the locating feature 18 and is configured to receive
the subcores 22. The housing 10 may be manufactured by casting or
other suitable process. In certain embodiments, the locating
feature 18 may be machined into the housing. Alternatively, the
locating feature 18 may be cast or machined separately and then
assembled to the housing 10 by a shrink-fit, press-fit, welding,
fastening, or other suitable process.
[0035] Having at least partially manufactured the housing 10 and
subcores 22, the method 200 may include an operation 240 of
inserting the subcores 22 within the cavity 12 of the housing 10
such that each subcore 22 seats against at least one locating
feature 18. The subcores 22 may be inserted into the housing 10 and
retained therein by a shrink-fit between the subcores 22 and
housing 10, by a press-fit, by a mechanical fastener, by an
adhesive, and/or by other suitable means. With the subcores 22
inserted into the housing 10, the method 200 may include an
operation 250 of installing the windings through and around the
winding channels 32 of the subcores 22 to form the stator 20. The
operation 250 may include further processes such as winding the
windings 30 from separate strands of wire, bundling and insulating
the windings 30 of one winding channel 32 from the windings 30 of
another winding channel 32, lining the each winding channel 32 of
the subcores 22 with insulation, and other appropriate processes to
prevent electrical shorts between the windings 30 and the subcores
22. The method 200 may further include an operation 260 of
inserting the rotor/shaft assembly 14 into the housing 10 within
the stator 20 to form the machine 100. The operation 260 may
include further processes such as placing bearings on opposing ends
of a shaft of the rotor/shaft assembly 14, and assembling covers on
opposing ends of the housing 10 to cap the housing 10 such that the
shaft of the rotor/shaft assembly 14 extends through the cover. In
embodiments including the fan 56 and/or conduit 58, the method 200
may include an operation of connecting the fan 56 and/or conduit 58
to the machine 100.
[0036] In at least one embodiment according to the present
disclosure, a method of manufacturing the machine 100 may include
an alternative operation of fabricating the subcores 22. In such an
embodiment, the subcores 22 may be manufactured individually as an
integral whole, instead of as an assembly of laminations 24. The
subcores 22 may be cast, machined, molded, or manufactured by any
suitable process. Suitable machining processes may include
electrical discharge machining ("EDM"). In at least one embodiment,
the subcores 22 may be manufactured using an additive manufacturing
process. Additive manufacturing is the process of forming an
article by the selective fusion, sintering, or polymerization of a
material stock. Additive manufacturing includes the use of a
discretized computer-aided design ("CAD") data model of a desired
part to define layers that may be processed successively in
sequence to form the final integrated part. Additive manufacturing
includes powder bed fusion ("PBF") and powder spray fusion ("PSF")
manufacturing processes, including selective laser melting, direct
metal laser sintering, selective laser sintering, and electron beam
melting. PBF and PSF processes share a basic set of process steps,
including one or more thermal sources to induce melting and fusing
between powder particles of a material stock, a means for
controlling fusion of the powder particles within prescribed
regions of each layer of the discretized CAD model, and a means of
depositing the powder particles on the previously fused layers
forming the part-in-process. The prescribed regions of each layer
are defined by the cross-section of the part CAD model in a given
layer. Because the powder particles are melted and fused to the
previous layer, the resultant part may be solid, substantially
fully dense, substantially void-free, and has substantially
equivalent or superior thermal and mechanically properties of a
part manufactured by conventional molding, casting, or machining
methods. Alternatively, the resultant part may include a desired
degree of porosity by appropriate control of the manufacturing
process.
[0037] As is evident from the figures and text presented above, a
variety of embodiments of an electrical rotor machine and methods
for using and constructing the same according to the present
disclosure are contemplated. While the invention has been
illustrated and described in detail in the drawings and foregoing
description, the same is to be considered as illustrative and not
restrictive in character, it being understood that only certain
exemplary embodiments have been shown and described. Those skilled
in the art having the benefit of the present disclosure will
appreciate that many modifications, including equivalent
substitutions, are possible in the example embodiments without
materially departing from the scope of the invention. Accordingly,
all such modifications are intended to be included within the scope
of this disclosure as defined in the following claims.
[0038] In one aspect, the present disclosure includes a method of
manufacturing an electrical machine, the method comprising:
fabricating two or more subcores, the subcores including a
plurality of winding channels along an axial length of each
subcore, the winding channels structured to receive stator
windings; fabricating a housing having a wall defining a volume,
the housing structured to support the subcores within the volume,
the housing further including an aperture through the wall and a
locating feature structured to position the subcores; inserting
each subcore into the volume of the housing, wherein the subcores
seat against opposing sides of the locating feature, whereby a flow
channel is formed between the subcores, the flow channel aligned
and in communication with at least one of the aperture of the
housing; and installing the stator windings in the winding channels
of the subcores to form a stator within the housing, whereby the
stator windings extend through the winding channels of adjacent
subcores.
[0039] In refining aspects, the present disclosure includes a
method further comprising inserting a rotor and shaft assembly into
the housing within the stator; wherein the aperture and the flow
channel form a cooling path through the stator, the cooling path
configured to enable a coolant to flow between the subcores and
over the stator windings, wherein the locating feature is
positioned outside the cooling path; wherein the cooling path is
substantially perpendicular to a longitudinal axis of the machine;
wherein the subcores are shrink-fit to the housing; wherein the
subcores are fastened to the housing by a mechanical fastener or an
adhesive; wherein the stator comprises two subcores positioned by
the locating feature therebetween; wherein the housing comprises a
plurality of apertures circumferential spaced about the wall and
comprises a plurality of locating features positioned between the
apertures; wherein the locating feature is fabricated separately
from the housing and attached thereto.
[0040] In another aspect, the present disclosure includes a method
of manufacturing an electrical rotor machine, the method
comprising: fabricating a plurality of stator laminations, each
lamination including a plurality of slots; manufacturing at least
two subcores by assembling a prescribed portion of the plurality of
laminations to form each subcore, wherein the plurality of slots of
the laminations are aligned to form a plurality of winding channels
through each subcore along a longitudinal axis, the winding
channels structured to receive stator windings; fabricating a
housing defining a cavity, the housing structured to support the
subcores within the cavity and including a plurality of apertures
formed therethrough to enable a flow of a coolant into the cavity,
wherein the housing further includes a feature structured to locate
the subcores within the cavity, wherein the feature is disposed
within the cavity between the apertures; inserting each subcore
into the housing such that the subcores are separated by the
feature of the housing to form a flow channel between each subcore,
the flow channel in fluid communication with at least one of the
apertures of the housing; installing the stator windings in the
winding channels of the subcores to form a stator within the
housing, whereby the stator windings extend through the winding
channels of adjacent subcores; and inserting a rotor and shaft
assembly into the housing within the stator.
[0041] In refining aspects, the present disclosure includes a
method wherein the apertures and the flow channel form a cooling
path through the stator, the cooling path configured to enable a
coolant to flow between the subcores and over the stator windings,
wherein the feature of the housing is positioned outside the
cooling path.
[0042] In another aspect, the present disclosure includes an
electrical rotor machine comprising: a housing including a wall
defining a volume and including a locating feature on the wall
within the cavity, the housing including an aperture through the
wall adjacent the locating feature; a stator comprising: two
subcores disposed within the cavity and seated against opposing
edges of the locating feature, wherein a radial channel is formed
between the subcores, the radial channel in fluid communication
with the aperture of the housing, and wherein the subcores further
including a plurality of winding channels along an axial length of
each subcore, the plurality of winding channels structured to
receive stator windings, and stator windings disposed within the
plurality of winding channels of the subcores, wherein the stator
windings extend between the subcores and across the radial channel;
and a rotor operably attached to a shaft and disposed within the
stator, the shaft structured to rotate about a longitudinal axis of
the machine.
[0043] In refining aspects, the present disclosure includes a
machine wherein the housing comprises a plurality of apertures
circumferential spaced about the wall and comprises a plurality of
locating features positioned between the apertures; wherein the
radial channel is substantially perpendicular to the longitudinal
axis; wherein the rotor is positioned relative to the stator to
form a gap therebetween, the gap extending axially and
substantially parallel to the longitudinal axis, the gap further in
fluid communication with the radial channel; wherein each subcore
comprises a plurality of ducts radially spaced from the winding
channels and substantially parallel to the longitudinal axis, the
ducts in fluid communication with the radial channel and extending
from the radial channel to opposing sides of each subcore.
[0044] Further, in describing representative embodiments, the
disclosure may have presented a method and/or process as a
particular sequence of operations. However, to the extent that the
method or process does not rely on the particular order of
operations set forth herein, the method or process should not be
limited to the particular sequence of operations described. Other
sequences of operations may be possible. Therefore, the particular
order or sequence of the operations disclosed herein should not be
construed as limitations of the present disclosure. Such sequences
may be varied and still remain within the scope of the present
disclosure.
* * * * *