U.S. patent application number 12/987839 was filed with the patent office on 2011-07-14 for induction motor.
Invention is credited to Arnold M. Heitmann.
Application Number | 20110169355 12/987839 |
Document ID | / |
Family ID | 44245536 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110169355 |
Kind Code |
A1 |
Heitmann; Arnold M. |
July 14, 2011 |
INDUCTION MOTOR
Abstract
Exemplary embodiments of the present invention relate to an
induction motor including a stator having a circular cross-section
and an inner passage having a longitudinal axis defining a bore, a
solid core steel rotor having a circular cross-section rotatably
disposed within the bore of the stator, and an air gap disposed
between the rotor and the stator. A copper conductive layer is
disposed on the steel rotor to increase the electrical conductance
of the rotor. Exemplary embodiments adhere the copper conductive
layer to the steel rotor using Hot Isostatic Pressing (HIP). The
HIP process encloses the steel rotor and the copper conductive
layer in a containment vessel, and adheres the conductive layer to
the rotor by applying high temperature and high gas pressure to the
outside of the containment vessel.
Inventors: |
Heitmann; Arnold M.;
(Rowley, MA) |
Family ID: |
44245536 |
Appl. No.: |
12/987839 |
Filed: |
January 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61323073 |
Apr 12, 2010 |
|
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|
61293990 |
Jan 11, 2010 |
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Current U.S.
Class: |
310/63 ; 29/598;
310/210; 310/90 |
Current CPC
Class: |
Y10T 29/49012 20150115;
H02K 1/32 20130101; H02K 17/16 20130101; H02K 9/06 20130101 |
Class at
Publication: |
310/63 ; 310/210;
310/90; 29/598 |
International
Class: |
H02K 17/16 20060101
H02K017/16; H02K 9/06 20060101 H02K009/06; H02K 7/08 20060101
H02K007/08; H02K 15/02 20060101 H02K015/02 |
Claims
1. An induction motor, comprising: a stator having a circular
cross-section and an inner passage having a longitudinal axis
defining a bore; a steel rotor having a circular cross-section
rotatably disposed within the bore of the stator; and a layer of
copper integrally adhered to an outer surface of the solid core
steel rotor using Hot Isostatic Pressing (HIP).
2. The induction motor of claim 1, wherein the rotor comprises: an
axial fan for directing incoming air in an axial direction around
the rotor.
3. The induction motor of claim 1, wherein the rotor is a solid
core steel rotor.
4. The induction motor of claim 1, further comprising: an oil
lubrication system for lubricating motor bearings in the induction
motor, the oil lubrication system comprising: an oil filter for
filtering a lubricating oil used for lubricating the motor
bearings, a heat exchanger for cooling the filtered oil, and an oil
applicator for transferring the oil onto the motor bearings.
5. The induction motor of claim 1, further comprising: an oil
applicator for applying a lubricating oil to motor bearings in the
induction motor, the oil applicator comprising: a piece of felt
that allows uniform distribution of the oil in the oil applicator,
and an oil slinger that slings the oil onto the motor bearings.
6. The induction motor of claim 1, further comprising: motor
bearings that are lubricated using an oil applicator, the oil
applicator comprising: a piece of felt that allows uniform
distribution of a lubricating oil in the oil applicator, and an oil
slinger that slings the lubricating oil onto the motor
bearings.
7. An induction motor, comprising: a stator having a circular
cross-section and an inner passage having a longitudinal axis
defining a bore; a solid core steel rotor having a circular
cross-section rotatably disposed within the bore of the stator, the
rotor including an axial fan for directing incoming air in an axial
direction around the rotor; and a layer of copper integrally
adhered to an outer surface of the solid core steel rotor using Hot
Isostatic Pressing (HIP).
8. The induction motor of claim 7, further comprising: an oil
lubrication system for lubricating motor bearings in the induction
motor, the oil lubrication system comprising: an oil filter for
filtering oil used for lubricating the motor bearings, a heat
exchanger for cooling the filtered oil, and an oil applicator for
transferring the oil onto the motor bearings.
9. The induction motor of claim 7, further comprising: an oil
applicator for applying a lubricating oil to motor bearings in the
induction motor, the oil applicator comprising: a piece of felt
that allows uniform distribution of the oil in the oil applicator,
and an oil slinger that slings the oil onto the motor bearings.
10. The induction motor of claim 7, further comprising: motor
bearings that are lubricated using an oil applicator, the oil
applicator including: a piece of felt that allows uniform
distribution of a lubricating oil in the oil applicator, and an oil
slinger that slings the lubricating oil onto the motor
bearings.
11. A method of manufacturing a solid core steel rotor for an
induction motor, the method comprising: adhering a copper layer
over an outer surface of the solid core steel rotor using Hot
Isostatic Pressing (HIP).
Description
RELATED APPLICATIONS
[0001] This application is related to and claims priority to U.S.
Provisional Application Ser. No. 61/293,990 filed Jan. 11, 2010 and
to U.S. Provisional Application Ser. No. 61/323,073 filed Apr. 12,
2010. The entire contents of the aforementioned applications are
expressly incorporated herein by reference in their entirety.
BACKGROUND
[0002] Induction motors known as solid rotor machines include a
stator and a solid steel rotor rotatably disposed within a bore of
the stator. A conductive layer may be provided on the outer
operating surface of the rotor to increase the electrical
conductance in the rotor. Conventional techniques of providing a
copper layer on a steel rotor make use of air and electric means of
propelling high-velocity molten copper against the rotor surface.
Examples of such conventional techniques include blast coating and
vapor deposition.
[0003] Conventional techniques do not produce adequate adhesion of
the copper conductive layer to a solid core steel rotor. The
copper-steel bond created by conventional techniques is not
adequately strong to withstand high rotational speeds.
Additionally, these techniques lead to oxidation and porosity of
the copper conductive layer. Oxidation and porosity of the
resulting copper conductive layer raises the electrical resistance,
which necessitates a thicker conductive layer. The rise in
electrical resistance increases the apparent air gap between the
rotor and the stator, and leads to higher electrical losses in the
motor.
SUMMARY
[0004] Exemplary embodiments of the present invention avoid the
shortcomings of conventional techniques of providing a conductive
layer on a steel rotor by using Hot Isostatic Pressing (HIP) to
adhere the conductive layer to the steel rotor. In exemplary
embodiments, the conductive layer is pure or substantially pure
copper layer, and the rotor is a solid core steel rotor. The HIP
process encloses the solid core steel rotor, a copper layer sleeve,
and two copper layer end caps in a containment vessel, and adheres
the copper layer sleeve and end caps to the solid core steel rotor
by applying high temperature and high gas pressure to the outside
of the containment vessel.
[0005] The HIP process creates a strong integral bond between the
steel rotor and the copper layer. The resulting copper layer
adhered to the rotor is non-porous, which improves its performance
as an electrical conductor between the rotor and the stator. The
resulting copper layer is also free of contaminants like oxidation,
moisture, oil, etc., and is not affected by oxidation on the faying
surfaces. These properties also enhance the electrical conductance
between the rotor and the stator.
[0006] In accordance with one exemplary embodiment, an induction
motor is provided. The induction motor includes a stator having a
circular cross-section and an inner passage having a longitudinal
axis defining a bore. The induction motor also includes a steel
rotor having a circular cross-section rotatably disposed within the
bore of the stator. The rotor includes an axial fan that directs
incoming air in an axial direction around the rotor.
[0007] In accordance with another exemplary embodiment, an
induction motor is provided. The induction motor includes a stator
having a circular cross-section and an inner passage having a
longitudinal axis defining a bore. The induction motor also
includes a solid core steel rotor having a circular cross-section
rotatably disposed within the bore of the stator. The induction
motor further includes a layer of copper integrally adhered to the
outer surface of the solid core steel rotor using Hot Isostatic
Pressing (HIP).
[0008] In accordance with yet another exemplary embodiment, an
induction motor is provided. The induction motor includes a stator
having a circular cross-section and an inner passage having a
longitudinal axis defining a bore. The induction motor also
includes a solid core steel rotor having a circular cross-section
rotatably disposed within the bore of the stator. The rotor
includes an axial fan that directs incoming air in an axial
direction around the rotor. The induction motor further includes a
layer of copper integrally adhered to the outer surface of the
solid core steel rotor using Hot Isostatic Pressing (HIP).
[0009] In accordance with still another exemplary embodiment, a
method of manufacturing a solid core steel rotor in an induction
motor is provided. The method includes adhering a copper layer over
an outer surface of the solid core steel rotor using Hot Isostatic
Pressing (HIP).
[0010] In accordance with a further exemplary embodiment, an oil
applicator for lubricating motor bearings is provided. The oil
applicator includes felt applicator that allows uniform
distribution of oil from the oil applicator. The oil applicator
applies oil onto an oil slinger that slings oil onto the motor
bearings.
[0011] In accordance with yet another exemplary embodiment, a
method of lubricating motor bearings is provided. The method
includes distributing oil uniformly using a felt applicator of an
oil applicator. The method also includes slinging the oil onto the
motor bearings using an oil slinger in close proximity to the oil
applicator.
[0012] In accordance with still another exemplary embodiment, an
induction motor is provided. The induction motor includes bearings
that are lubricated using an oil applicator. The oil applicator
includes felt that allows uniform distribution of oil from the oil
applicator. The oil applicator applies the oil onto an oil slinger
that slings oil onto the motor bearings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing and other objects, aspects, features, and
advantages of exemplary embodiments will become more apparent and
may be better understood by referring to the following description
taken in conjunction with the accompanying drawings, in which:
[0014] FIG. 1 illustrates an exemplary motor provided in accordance
with exemplary embodiments.
[0015] FIG. 2 is a longitudinal section taken through an exemplary
steel rotor that is coated with an exemplary conductive layer using
the Hot Isostatic Pressing (HIP) process.
[0016] FIG. 3 is a transverse section taken through the middle of
an exemplary steel rotor that is coated with an exemplary
conductive layer using the HIP process.
[0017] FIG. 4 is a flowchart that illustrates an exemplary method
of adhering a conductive layer to a solid core steel rotor using
the HIP process.
[0018] FIG. 5 illustrates an exemplary shaft body of a steel rotor
before the rotor is assembled with the conductive layer.
[0019] FIG. 6 illustrates an exemplary conductive layer end cap
before the conductive layer end cap is assembled with the
rotor.
[0020] FIG. 7 illustrates an exemplary conductive layer sleeve
before the conductive layer sleeve is assembled with the rotor.
[0021] FIG. 8 illustrates the exemplary conductive layer sleeve of
FIG. 7 and the conductive layer end caps of FIG. 6 assembled over
the exemplary shaft body of FIG. 5.
[0022] FIG. 9 illustrates an exemplary containment chamber of HIP
process that is adhered to the conductive layer and rotor assembly
of FIG. 8.
[0023] FIG. 10A illustrates a side view of an exemplary motor
assembly including a rotor and a fan shroud.
[0024] FIG. 10B illustrates a view of a motor fan assembly
including a set of fan blades provided integrally with a rotor and
a set of stationary vanes affixed to a fan shroud.
[0025] FIG. 11 illustrates an exemplary set of fan blades that are
positioned axially along an exemplary rotor.
[0026] FIG. 12 illustrates an exemplary set of fan blades that are
positioned radially on an exemplary rotor, and a set of stationary
vanes positioned on the stator to convert the radial flow into an
axial flow.
[0027] FIG. 13A illustrates an exemplary shroud of a fan system
having exemplary stationary vanes affixed thereto.
[0028] FIG. 13B illustrates a stationary vanes before being affixed
to the exemplary shroud of FIG. 13A.
[0029] FIG. 13C illustrates a close-up view of the exemplary
stationary vanes affixed to the exemplary shroud of FIG. 13A.
[0030] FIG. 14 illustrates an exemplary oil system for lubricating
motor bearings.
[0031] FIG. 15 illustrates a longitudinal section through an
exemplary oil applicator in the exemplary oil system of FIG.
14.
DETAILED DESCRIPTION
[0032] Exemplary embodiments of the present invention relate to a
solid rotor induction motor including a stator having a circular
cross-section and an inner passage having a longitudinal axis
defining a bore, a solid core steel rotor having a circular
cross-section rotatably disposed within the bore of the stator, and
an air gap disposed between the rotor and the stator. A copper
conductive layer is disposed on the outer surface and end surfaces
of the steel rotor to increase the electrical conductance of the
rotor. Exemplary embodiments adhere the copper conductive layer to
the steel rotor using Hot Isostatic Pressing (HIP). The HIP process
encloses the steel rotor and the copper conductive layer in a
containment vessel, and adheres the conductive layer to the rotor
by applying high temperature and high gas pressure to the outside
of the containment vessel.
[0033] The resulting conductive layer adhered to the rotor is
non-porous, which improves its performance as an electrical
conductor between the rotor and the stator. The resulting
conductive layer is also free of contaminants like moisture, oil,
etc., and is not affected by oxidation on the faying surfaces.
These properties also enhance the electrical conductance between
the rotor and the stator.
[0034] FIG. 1 illustrates an exemplary motor 10. The motor 10
includes bearings 14, a stator 50, and a rotor 20 mounted within a
bore of the stator 50. In exemplary embodiments, the motor 10 runs
typically between about 30,000 and 100,000 rpm.
[0035] The stator 50 includes stator winding 56, an inner surface
54 facing the rotor 20, and a bore 52 extending along a
longitudinal axis X.
[0036] An air gap 60 is formed between the inner surface 54 of the
stator 50 and a conductive layer 30 provided over the outer surface
of the rotor 20. In exemplary embodiments, the air gap 60 has a
thickness of 0.1 inches. Cool air is introduced through the rotor
20, and is thereafter applied axially through the air gap 60.
[0037] The size of the air gap 60 has significance in the
high-speed technical applications of the motor 10, especially with
relation to its efficiency. More specifically, increasing the air
gap optimizes the efficiency of the motor by decreasing drag
losses. As such, the air gap in exemplary embodiments has an
average thickness of 0.1 inches, which is substantially larger than
conventional air gaps which have an average thickness of 0.015
inches. U.S. Pat. No. 5,473,211 discusses the relationship between
the air gap thickness and motor efficiency, and is herein
incorporated in its entirety by reference.
[0038] Providing a thicker air gap in exemplary embodiments permits
sufficient cooling air to be applied axially to the air gap 60,
which provides a heat sink for both the rotor 20 and the stator 50.
An unexpected result of exemplary embodiments is that the flow of
cooling air through the air gap 60 adequately cools the rotor 20
and the stator 50 with minimum power consumption. The motor 10 may
thus operate efficiently without an external or auxiliary mechanism
cooling the rotor 20 and the stator 50.
[0039] The rotor 20 is rotatably disposed within the bore 52 of the
stator 50 along the longitudinal axis X. The rotor 20 rotates
relative to the stator 50. The rotor 20 includes a shaft body 22,
and a conductive layer 30 that is adhered to the entire operating
outer surface of the rotor 20 using the Hot Isostatic Pressing
(HIP) process. The shaft body 22 is magnetically and electrically
conductive, and may be solid or hollow. The outer surface of the
shaft body is integral, but can be identified as having an outer
circumferential portion 24 and two end portions 26 and 28.
[0040] The conductive layer 30 is a material with a high electrical
conductance provided to serve as a conductor for the electrical
current flowing through and over the rotor 20. The electrical
current traveling through and over the rotor should substantially
run in the conductive layer in order to minimize current-heat
losses.
[0041] In an exemplary embodiment, the rotor 20 in the motor 10 has
a conductive layer 30 adhered to the outer surface of the shaft
body 22 of the rotor 20 using Hot Isostatic Pressing (HIP). In the
exemplary embodiment, the rotor 20 is a solid core steel rotor, and
the conductive layer 30 is pure or substantially pure copper. The
copper layer 30 may have an average thickness of about 1-3 mm, with
a preferred embodiment having a thickness of about 1 mm. The ideal
copper layer thickness for a particular motor is determined based
on variables specific to the motor, e.g., flux path, flux losses,
etc.
[0042] FIGS. 2 and 3 illustrate an exemplary shaft body 22 of a
rotor 20 coated with an exemplary copper layer 30 using the HIP
process. The final copper layer 30--adhered to the shaft body
22--is a single, integral unit, but may be identified as having
three portions in an exemplary embodiment: a copper layer sleeve 32
and two copper layer end caps 34 and 36. The copper layer sleeve 32
is disposed on the outer circumferential portion 24 of the shaft
body 22 that runs along the stator 50. The copper layer sleeve 32
serves as a conductor for the flux flowing across the air gap 60 to
induce a current flow in the conductive layer. The copper layer end
caps 34 and 36 are disposed on the end portions 26 and 28,
respectively, of the shaft body 22. The copper layer end caps 34
and 26 provide a short circuit flux path across the rotor 20 to
engage with complementary stator poles, which is necessary for the
induction machine to function. In other exemplary embodiments, the
copper layer 30 may be identified as having fewer or more than the
above-identified portions.
[0043] In an exemplary embodiment, the copper layer 30 has uniform
thickness over the shaft body 22, such that the copper layer sleeve
32 and the conductive layer end caps 34 and 36 have the same
thickness. In another exemplary embodiment, the copper layer 30 is
thicker at the conductive layer end caps 34 and 36 than at the
copper layer sleeve 32.
[0044] FIG. 2 is a longitudinal section taken through a rotor 20
with a copper layer 30 adhered to the outer surface of the rotor
20. The rotor 20 includes an outer circumferential portion 24 and
two end portions 26 and 28. The copper layer sleeve 32 extends over
the outer circumferential portion 24 of the shaft body 22 to join
electrically with copper layer end caps 34 and 36. In addition, the
two copper layer end caps 34 and 36 are electrically attached to
the end portions 26 and 28, respectively, of the shaft body 22.
[0045] FIG. 3 is a transverse section taken through the middle of a
rotor 20 with a copper layer 30 adhered to the outer surface of the
rotor 20. The shaft body 22 is a steel body. The outer
circumferential portion 24 of the shaft body 22 is coated with the
copper layer sleeve 32.
[0046] Exemplary embodiments of the present invention avoid the
shortcomings of conventional techniques of providing a copper
conductive layer on a steel rotor by using the Hot Isostatic
Pressing (HIP) process to adhere the copper layer 30 to the shaft
body 22 of the rotor 20. The HIP process subjects the outside of a
high-pressure containment vessel enclosing the shaft body 22 and
the copper layer 30 to both elevated temperature and isostatic gas
pressure. The elevated temperature and isostatic gas pressure
causes the copper layer 30 to integrally adhere to the shaft body
22.
[0047] FIG. 4 is a flowchart that illustrates an exemplary method
of adhering the copper layer 30 to the steel shaft body 22 of the
rotor 20 using the HIP process. In step 1 of FIG. 4, the copper
layer 30 and the rotor 20 are pre-processed before the start of the
HIP process. Pre-processing may involve cleaning the copper layer
and the rotor to remove contaminants like oil, oxidation, moisture,
etc. Pre-processing may also involve ensuring that the copper layer
and the rotor are free of contaminants. Pre-processing may further
involve sealing the copper layer and the rotor, e.g., in vacuum
packs, to ensure that the copper layer and rotor do not become
re-contaminated before their transfer to the HIP location.
[0048] FIG. 5 illustrates the shaft body 22 of the rotor 20 before
or after pre-processing step 1, i.e., before the rotor is assembled
with the copper layer. FIG. 6 illustrates the copper layer end cap
34, 36 before or after pre-processing step 1, i.e., before the
copper layer end caps are assembled with the rotor. FIG. 7
illustrates the copper layer sleeve 32 before or after
pre-processing step 1, i.e., before the copper layer sleeve is
assembled with the rotor.
[0049] In steps 2 and 3 of FIG. 4, the copper layer 30 and the
rotor 20 are assembled together before the HIP process adheres the
copper layer to the rotor. The copper layer sleeve 32 is assembled
over the outer circumferential portion 24 of the shaft body 22 of
the rotor 20. The copper layer end caps 34 and 36 are assembled
over the end portions 26 and 28, respectively, of the shaft body 22
of the rotor 20. In the assembly, the copper layer end caps 34 and
36 abut the copper layer sleeve 32. This negates the need for a
stressed weld between the sleeve and the end caps.
[0050] FIG. 8 illustrates the copper layer sleeve 32 assembled over
the outer circumferential portion 24 of the shaft body 22 of the
rotor 20, and the copper layer end caps 34 and 36 assembled over
the end portions 26 and 28, respectively, of the shaft body 22 of
the rotor 20. In this assembly, the copper layer 30 fits loosely
over the rotor 20. However, the copper layer and the rotor are
clean and free of contaminants, and there is no oxidation on the
faying surfaces.
[0051] Steps 4-7 of FIG. 4 outline the HIP process. In step 4, the
rotor assembly is introduced into the containment chamber 70 of the
HIP process. In step 5, the containment chamber is welded to the
shaft body 22 assembled with the copper layer 30. A high vacuum is
pulled on the containment chamber and the chamber is subjected to
high temperatures to remove air and moisture through a gas
introduction spigot 72. In an exemplary embodiment, the containment
chamber may be purged with an inert gas, such as argon, prior to
being evacuated. In step 6, the gas introduction spigot 72 is
sealed off and the entire assembly is subjected to high temperature
and high pressure.
[0052] FIG. 9 illustrates an exemplary containment chamber 70
adhered to the rotor assembly, and an exemplary gas introduction
spigot 72 attached to the containment chamber 70.
[0053] In step 7, the high temperature and high pressure outside
the containment chamber causes the copper layer 30 to integrally
adhere to the shaft body 22 of the rotor 20. More specifically, the
copper layer sleeve 32 adheres integrally to the outer
circumferential portion 24 of the shaft body 22, and the copper
layer end caps 34 and 36 adheres integrally to the end portions 26
and 28, respectively, of the shaft body 22. The HIP process also
adheres the copper layer sleeve 32 to the copper layer end caps 34
and 36 such that the entire copper layer 30 and the rotor 20 is a
single integral unit.
[0054] The high temperature and high gas pressure employed in the
HIP process eliminate internal voids in the copper layer 30, and
create a clean and uniform bond between the copper layer 30 and the
rotor 20. The resulting copper layer is not porous, which improves
its performance as an electrical conductor between the rotor and
the stator. The resulting copper layer is also free of contaminants
like oxidation, moisture, oil, etc., and is not affected by
oxidation on the faying surfaces. These properties also enhance the
electrical conductance between the rotor and the stator.
Conventional techniques of providing a copper layer on a steel
rotor cannot provide these advantageous characteristics.
[0055] In step 8 of FIG. 4, after the completion of the HIP
process, the containment chamber 70 is machined off from the rotor
assembly. FIG. 2 illustrates the rotor assembly after the
containment chamber has been machined off.
[0056] In another exemplary embodiment, the rotor 20 in the motor
10 has a conductive layer 30 adhered to the outer surface of the
shaft body 22 of the rotor 20 using Hot Isostatic Pressing (HIP).
The rotor 20 is a solid core steel rotor, and the conductive layer
30 is pure or substantially pure copper. In this exemplary
embodiment, an exemplary fan system of the motor 10 includes a set
of fan blades 40 affixed to the outer surface of the rotor 20. An
exemplary fan system also includes a set of stationary vanes 42
affixed to a fan shroud 44. The fan blades 40 and the stationary
vanes 42 are configured to allow incoming air to flow through the
air gap 60 substantially in an axial direction. This allows the fan
blades 40 to impart a velocity increase to the incoming cooling
air, and to increase the static pressure of the incoming air. This
induces the incoming air to flow into an opening of the air gap 60
at a high velocity.
[0057] FIG. 10A illustrates a side view of an exemplary motor
assembly including a rotor 20 and a fan shroud 44. FIG. 10B
illustrates a view of a motor fan assembly including a set of fan
blades 40 provided integrally with a rotor and a set of stationary
vanes 42 affixed to a fan shroud.
[0058] In an exemplary configuration, illustrated in FIG. 11, the
fan blades 40 are positioned axially around the rotor 20, and a set
of stationary vanes 42 is used to divert the radial flow into an
axial flow along the air gap 60. The incoming air arriving from the
axial fan blades 40 has a tangential component and an axial
component. The stationary vanes 42 turn the net velocity vector of
the incoming air axially. This axial turning of the net velocity
vector significantly increases the static pressure, thus inducing
the incoming air to flow into an opening of the air gap 60 at high
speed and high pressure.
[0059] In another exemplary embodiment, the rotor 20 in the motor
10 has an axial fan 40 affixed to the outer surface of the rotor 20
to introduce air axially into the air gap 60. The fan blades 40 are
configured to allow incoming air to flow through the air gap 60
substantially in an axial direction. This allows the fan blades 40
to impart a velocity increase to the incoming cooling air, and to
increase the static pressure of the incoming air. This induces the
incoming air to flow into an opening of the air gap 60 at a high
velocity.
[0060] In yet another exemplary configuration, illustrated in FIG.
12, the fan blades 40 are positioned radially on the rotor 20, and
a diverting mechanism 46 positioned downstream from the fan blades
40 directs incoming air from a radial direction to an axial
direction along the air gap 6. A set of stationary vanes 42 is used
to further direct the incoming air into an axial flow along the air
gap 60. The set of stationary vanes 42 is provided integrally on
the inner surface 54 of the stator 50. The set of stationary vanes
42 is disposed downstream from the fan blades 40 and the diverting
mechanism 46.
[0061] The fan system of the motor includes an exemplary shroud 44
which guides the incoming air into contact with the fan blades 40
and the stationary vanes 42. In exemplary embodiments, the shroud
44 may have an inlet curvature to assist in introducing the
incoming air into the rotating blading. In an exemplary embodiment,
the shroud 44 may be fixed to the stator winding 56 of the stator
50. FIG. 13A illustrates a longitudinal section taken through an
exemplary rotor 20 with an exemplary shroud 44 having exemplary
stationary vanes 42 affixed thereto. FIG. 13B illustrates a
detailed view of the exemplary vanes 42 before being affixed to the
exemplary shroud 44 of FIG. 13A. FIG. 13C illustrates a close-up
view of the exemplary stationary vanes 42 affixed to the exemplary
shroud 44 of FIG. 13A.
[0062] The set of fan blades 40 is affixed to the rotor 20 after
the HIP process, i.e., after step 8 of FIG. 4.
[0063] In still another exemplary embodiment, an oil system is
provided for lubricating the bearings of a motor. The oil system
provided by exemplary embodiments is designed and configured to
provide lubrication to high-speed motor bearings, while limiting
oil flow to prevent heat build-up that can be caused by excessive
oil flow.
[0064] A motor provided by exemplary embodiments, operating at
about 42,000 rpm, requires an oil flow of about 0.0025 liters per
minute to lubricate and cool the bearings of the motor. The speed
of oil injected into the high-speed bearing needs to be close to
the peripheral speed of the bearing, i.e., about 220 feet per
second. One conventional methodology of achieving this oil speed
uses an oil nozzle to supply the oil to the bearing and raises an
upstream oil pressure to about 260 psig. This methodology requires
a corresponding nozzle opening of about 0.0015 inches in diameter.
Such a small nozzle opening is not suitable for the purposes of
lubricating and cooling a motor bearing, as it carries a high risk
of blockage and may negatively affect good oil filtering and
passage cleanliness in the oil lubrication system.
[0065] Another conventional methodology introduces the oil flow to
the motor bearing from an oil reservoir via a felt wick. The felt
wicks or lifts oil from an oil reservoir. The felt wick is located
close to a conical surface on the shaft of the motor that acts as
an oil slinger. This methodology may be practical for use with
small turbochargers, but the ability of a wick to lift oil from a
nearby oil reservoir is limited by the height of the raised portion
of the wick from the oil reservoir.
[0066] The oil system taught by exemplary embodiments overcome the
limitations of conventional methodologies by using a small oil pump
to introduce oil to a wick which then transfers the oil to a motor
bearing to lubricate and cool the bearing. FIG. 14 illustrates an
exemplary oil system 80 for lubricating motor bearings 14. The oil
system 80 includes an oil sump 82 which is a oil reservoir provided
at the bottom of the motor. Oil used to lubricate the motor
bearings pools in the oil sump 82. Oil from the oil sump 82 is
filtered in an oil filter 84 to remove undesirable particles from
the oil before it is used to lubricate the bearings.
[0067] After filtration, the oil is then pumped by a pump 86, e.g.,
an electric-powered piston pump, through an oil-to-ambient heat
exchanger 88 which cools the oil to be supplied to the motor
bearings 14. High temperatures may reduce the viscosity of oil,
which makes the oil film too thin for effective lubrication of the
bearings. To maintain the viscosity of the oil, the heat exchanger
88 removes excess heat from the oil before it is used in
lubricating the motor bearings 14. In an exemplary embodiment, the
entire flow of oil pumped by the pump 86 is passed through the heat
exchanger 88. A small portion of the pumped flow is directed to the
bearings 14, and the balance of the pumped flow is directed to the
oil sump 82. The pumped oil flow size (i.e., the flow size of the
oil pumped at the pump 86) can be much greater than the oil flow
that eventually reaches and that is required by the motor bearings
14. A suitable pump can thus be secured from commonly available
pump suppliers.
[0068] The filtered and cooled oil is then distributed between two
sets of orifices based on the lubrication needs in the motor: one
or more main flow control orifices 90 and one or more secondary
flow control orifices 92. The main flow control orifices 90 return
unused oil to the oil sump 82. The second flow control orifices 92
provide the oil to one or more oil applicators 94 that are in close
proximity or contact with an oil slinger 96 (FIG. 15), which, in
turn delivers the oil to the motor bearings 14. The oil flows into
the oil applicators 94 and is thereupon transferred to the oil
slinger 96. In exemplary embodiments, the oil applicators 94 may
include a shortened wick through which the oil is transferred to
the oil slinger 96. In exemplary embodiments, the oil applicators
94 may include felt which is highly oil absorbent and has great
wicking capabilities.
[0069] FIG. 15 illustrates a longitudinal section through an
exemplary oil applicator 94 in the exemplary oil system 80 of FIG.
14. The oil applicator 94 applies oil to the oil slinger 96 which
slings the oil arriving through the secondary oil flow control
orifices 92. The slinging action transfers the oil to the lip of
the oil slinger 96, after which is it deposited onto the bearings
14. The oil applicator 94 is also equipped with one or more pieces
of felt 98 which allows uniform distribution of the oil slung by
the oil slinger 96, and ensures that an optimum amount of oil is
used to lubricate the bearings 14.
[0070] In a further exemplary embodiment, a motor 10 is provided
with bearings 14 lubricated using the exemplary oil system 80
illustrated in FIGS. 14 and 15.
[0071] One of ordinary skill in the art will appreciate that the
present invention is not limited to the specific exemplary
embodiments described herein. Many alterations and modifications
may be made by those having ordinary skill in the art without
departing from the spirit and scope of the invention. Therefore, it
must be expressly understood that the illustrated embodiments have
been shown only for the purposes of example and should not be taken
as limiting the invention, which is defined by the following
claims. One of ordinary skill in the art will appreciate that any
number of the illustrated embodiments may be implemented together.
These claims are to be read as including what they set forth
literally and also those equivalent elements which are
insubstantially different, even though not identical in other
respects to what is shown and described in the above
illustrations.
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