U.S. patent application number 13/243504 was filed with the patent office on 2012-01-19 for encapsulated outer stator isolated rotor stepper motor valve assembly.
This patent application is currently assigned to NIDEC MOTOR CORPORATION. Invention is credited to John S. Bandas, Randall R. Floyd, Kawall Malhotra, Michael E. Moore, Terry J. Stuckey.
Application Number | 20120012772 13/243504 |
Document ID | / |
Family ID | 42239635 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120012772 |
Kind Code |
A1 |
Moore; Michael E. ; et
al. |
January 19, 2012 |
ENCAPSULATED OUTER STATOR ISOLATED ROTOR STEPPER MOTOR VALVE
ASSEMBLY
Abstract
An electric motor assembly includes a rotor rotatable about an
axis and a stator spaced radially away from the rotor. An isolation
housing, configured to permit magnetic flux to flow therethrough
between the rotor and the stator, is disposed between the rotor and
the stator and defines an internal rotor chamber, in which the
rotor is located. The isolation housing fluidly isolates the
internal rotor chamber from the stator. An encapsulating cover is
provided that radially and axially surrounds the stator. The cover
is formed of a resin material and bonds the stator to the isolation
housing to prevent relative movement therebetween.
Inventors: |
Moore; Michael E.;
(Haubstadt, IN) ; Stuckey; Terry J.; (Evansville,
IN) ; Malhotra; Kawall; (Princeton, IN) ;
Floyd; Randall R.; (Evansville, IN) ; Bandas; John
S.; (Evansville, IN) |
Assignee: |
NIDEC MOTOR CORPORATION
St. Louis
MO
|
Family ID: |
42239635 |
Appl. No.: |
13/243504 |
Filed: |
September 23, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12336370 |
Dec 16, 2008 |
8053941 |
|
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13243504 |
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Current U.S.
Class: |
251/318 |
Current CPC
Class: |
H02K 5/128 20130101;
H02K 7/06 20130101; H02K 5/1672 20130101 |
Class at
Publication: |
251/318 |
International
Class: |
F16K 1/00 20060101
F16K001/00 |
Claims
1. A valve assembly for controlling pressurized fluid flow along a
conduit, said valve assembly comprising: a rotor rotatable about an
axis; a stator spaced radially away from the rotor; an isolation
housing disposed between the rotor and the stator and defining an
internal rotor chamber, in which the rotor is located, said
isolation housing being configured to permit magnetic flux to flow
therethrough between the rotor and the stator, said isolation
housing being configured for operable attachment to the conduit,
said isolation housing fluidly isolating the internal rotor chamber
from the stator; and a shaft disposed along the axis, said shaft
being operable to shift axially between an extended position and a
retracted position, with rotation of the rotor causing axial
shifting of the shaft, said shaft carrying a valve body that is
shiftable into and out of the fluid conduit as the shaft shifts
between the extended position and the retracted position, said
isolation housing including a valve body chamber fluidly
connectable to the fluid conduit, said shaft projecting into the
valve body chamber, with the valve body being located within the
valve body chamber when the shaft is in the retracted position.
2. The valve assembly as claimed in claim 1, said rotor and said
shaft being threadably interconnected so as to translate rotational
movement of the rotor to axial linear movement of the shaft.
3. The valve assembly as claimed in claim 2, said rotor comprising
a radially inner element and a radially outer element, said
radially outer element being formed at least in part of magnetic
material, said radially inner element being formed of synthetic
resin material.
4. The valve assembly as claimed in claim 1, said isolation housing
comprising a generally cylindrical sleeve portion, said sleeve
portion presenting first and second axial margins, said isolation
housing including an end wall radially spanning the first margin to
substantially seal an end of the rotor chamber, said second margin
being substantially open.
5. The valve assembly as claimed in claim 4; and a bearing rigidly
fixed within the sleeve portion, said bearing at least partially
rotationally supporting the rotor.
6. The valve assembly as claimed in claim 4, said isolation housing
further comprising a connecting bell portion, said bell portion
presenting first and second axial margins, said first margin of the
bell portion being secured to the second margin of the sleeve
portion to define a junction therebetween, said second margin of
the bell portion being configured for operable attachment to the
pressurized fluid conduit.
7. The valve assembly as claimed in claim 6, said bell portion
including radially extending wall structure forming an endshield of
the rotor housing.
8. The valve assembly as claimed in claim 7; and a bearing rigidly
fixed within the bell portion, said bearing at least partially
rotationally supporting the rotor.
9. The valve assembly as claimed in claim 6, said bell portion
including radially extending wall structure having a substantially
flat surface aligned with and spaced generally parallel from the
axis, said shaft presenting a radially outer periphery, a portion
of which being substantially flat, said flat surface of the bell
portion bearing against the corresponding flat portion of the shaft
to thereby cooperatively prevent rotation of the shaft relative to
the bell portion.
10. The valve assembly as claimed in claim 9, said sleeve portion
including a generally solid segment along the first margin thereof
with an extended recess extending axially therein configured to
receive a portion of the shaft when the shaft is in the retracted
position.
11. The valve assembly as claimed in claim 1, said rotor and said
stator cooperatively forming a stepper motor.
Description
RELATED APPLICATION
[0001] This is a divisional of application Ser. No. 12/336,370
filed Dec. 16, 2008, which is hereby incorporated by reference
herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to an electric motor
assembly. More specifically, the present invention concerns an
electric motor assembly that is particularly useful in actuating a
valve body within a pressurized working fluid conduit, with the
motor assembly including an isolation housing in which the rotor is
located, with the housing serving to fluidly isolate the stator
from the rotor and from any contact with the working fluid.
[0004] 2. Discussion of the Prior Art
[0005] Those of ordinary skill in the art will appreciate that an
electric motor, such as a linear stepper motor, can be used for
many different applications, one of which involves shifting a valve
body of a valve assembly to control the flow of a working fluid
within a system. It is common to use such a stepper motor
controlled valve assembly to control the flow of a refrigerant with
a cooling system, and examples of such cooling systems are
disclosed in U.S. Pat. No. 6,076,368 ("the '368 patent") and U.S.
Pat. No. 6,272,870 ("the '870 patent").
[0006] When such a motor controlled valve system has been used in
the past, a conventional linear stepper motor has been enclosed
inside of a welded housing in order to seal the coolant inside the
system and prevent it from leaking out to the environment.
Traditionally, such a welded housing has included a steel container
bowl brazed to a threaded brass connector for associating the motor
control with the valve assembly. In addition, once a conventional
motor is placed within the steel housing, a top cover has been
welded onto the steel housing and wiring terminals, such as glass
beads, have been incorporated into the cover so that wiring leads
can be connected to power and control sources. In such a prior art
assembly, the entire motor assembly is disposed within the coolant
environment and all of the components are therefore exposed to the
working fluid.
[0007] While such conventional systems have been satisfactory in
some respects, those of ordinary skill in the art will also
appreciate that such a complex housing arrangement has resulted in
an expensive construction with poor reliability, as the multitude
of connections, including glass beads and welds, often become leak
points for the pressurized refrigerant. The disadvantages of
multiple leak points are typically exacerbated by the fact that
many of these assemblies are used in systems that experience high
vibration, such as a cooling assembly on a refrigerated truck.
Moreover, because the entire motor has been placed within the
welded housing, a small motor has been required in order to
maintain an acceptable overall footprint, a design constraint that
has limited the available motor power for evolving
applications.
[0008] As refrigerants or other working fluids are improved, or as
new substances are mandated by law, the operating pressure of the
fluid in newer systems is often significantly higher than in
previous iterations of such systems. For example, the new
refrigerant R-410-A requires an operating pressure that is between
about 50% and 70% higher than that of the previous refrigerant
R-22. Such an increase in the operating pressure of a conventional
system increases the likelihood of the working fluid leaking out to
the environment, and will require more powerful motors than can
currently be incorporated into the footprint provided by the welded
housing.
[0009] The prior art simply does not include an electric motor
assembly for use in a valve assembly that will satisfactorily seal
the pressurized working fluid within the system and that can
provide sufficient power as operating pressures increase.
SUMMARY
[0010] According to one aspect of the present invention, an
electric motor assembly is particularly configured for use with a
pressurized fluid. The inventive motor assembly provides an
isolation housing disposed between a rotor and a stator, wherein
the rotor is located within an internal rotor chamber defined by
the isolation housing and the stator is fluidly isolated from both
the chamber from any pressurized fluid within the system. Such a
construction eliminates the need for a welded outer shell,
consequently eliminating all welding leak points that could
otherwise allow the pressurized fluid to escape out into the
atmosphere.
[0011] Furthermore, the disposition of the stator outside of the
confined space of the isolation housing allows for a larger stator,
and consequently a more powerful electric motor, to be used in the
same overall footprint compared to prior art systems. The inventive
motor assembly also considerably reduces both component count and
assembly time compared to prior art assemblies. Finally, an
encapsulating cover can be incorporated to secure the stator to the
isolation housing, providing a clean aesthetic appearance and
protecting assembly elements against loosening from operational
vibration while providing sufficient heat transfer such that the
stator remains at an appropriate operating temperature.
[0012] According to one aspect of the present invention, an
electric motor assembly is provided that includes a rotor rotatable
about an axis and a stator spaced radially away from the rotor,
with the stator presenting an outer circumferential surface and
axial margins. An isolation housing is disposed between the rotor
and the stator and defines an internal rotor chamber, in which the
rotor is located. The isolation housing is configured to permit
magnetic flux to flow therethrough between the rotor and the
stator. The isolation housing is also configured for attachment to
a pressurized fluid conduit, with the isolation housing fluidly
isolating the internal rotor chamber from the stator. In addition,
the motor assembly includes an encapsulating cover radially and
axially surrounding the stator to overlie the outer circumferential
surface and axial margins of the stator. The cover bonds the stator
to the isolation housing to prevent relative movement therebetween,
and the cover is formed of a resin material.
[0013] Another aspect of the present invention concerns a valve
assembly for controlling pressurized fluid flow along a conduit.
The valve assembly includes a rotor rotatable about an axis and a
stator spaced radially away from the rotor. An isolation housing is
disposed between the rotor and the stator and defines an internal
rotor chamber, in which the rotor is located. The isolation housing
is configured to permit magnetic flux to flow therethrough between
the rotor and the stator. The isolation housing is also configured
for operable attachment to the conduit, with the isolation housing
fluidly isolating the internal rotor chamber from the stator. In
addition, the valve assembly includes a shaft disposed along the
axis, wherein the shaft is operable to shift axially between an
extended position and a retracted position, with rotation of the
rotor causing axial shifting of the shaft. The shaft carries a
valve body that is shiftable into and out of the fluid conduit as
the shaft shifts between the extended position and the retracted
position. The isolation housing includes a valve body chamber
fluidly connectable to the fluid conduit, and the shaft projects
into the valve body chamber, with the valve body being located
within the valve body chamber when the shaft is in the retracted
position.
[0014] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the detailed description of the preferred embodiments. This summary
is not intended to identify key features or essential features of
the claimed subject matter, nor is it intended to be used to limit
the scope of the claimed subject matter.
[0015] Various other aspects and advantages of the present
invention will be apparent from the following detailed description
of the preferred embodiments and the accompanying drawing
figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0016] A preferred embodiment of the present invention is described
in detail below with reference to the attached drawing figures,
wherein:
[0017] FIG. 1 is a perspective, partial cutaway view of an electric
motor assembly constructed in accordance with the principles of a
preferred embodiment of the present invention, depicting an
encapsulating cover surrounding the motor assembly, and further
depicting the motor assembly in an operational environment
including a valve housing with a valve body therein and fluid
conduit connections;
[0018] FIG. 2 is a perspective view of the electric motor assembly
of FIG. 1, shown from the opposite vantage point, depicting an
axial margin of an isolation housing and motor wiring extending out
through the encapsulating cover, illustrated without the
operational environment shown in FIG. 1;
[0019] FIG. 3 is a partial cutaway, perspective view of the
electric motor assembly of FIG. 1, depicting internal details of
construction of the motor assembly elements and the encapsulating
cover; and
[0020] FIG. 4 is an exploded, perspective view of the electric
motor assembly of FIG. 1, depicting individual elements of the
motor assembly, illustrated without the encapsulating cover shown
in FIG. 1.
[0021] The drawing figures do not limit the present invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the preferred
embodiments.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention is susceptible of embodiment in many
different forms. While the drawings illustrate, and the
specification describes, certain preferred embodiments of the
invention, it is to be understood that such disclosure is by way of
example only. There is no intent to limit the principles of the
present invention to the particular disclosed embodiments.
[0023] With initial reference to FIG. 1, an electric motor assembly
10 constructed in accordance with a preferred embodiment of the
present invention is depicted in connection with a valve assembly
12. The valve assembly 12 broadly includes a valve housing 14 that
is connectable to a fluid conduit 16. A sealing element 18, such as
an O-ring, is disposed between the valve housing 14 and the
electric motor assembly 10. The valve housing 14 includes flange
portions 20, 22 that are configured for attachment to an inlet
portion 24 and an outlet portion 26, respectively, of the conduit
16. The inlet portion 24 and the outlet portion 26 are in fluid
communication with one another via a passageway 28 defined within
the valve housing 14.
[0024] A valve body 30, such as a piston, is disposed within the
valve housing 14 and is configured for relative movement therein
such that at least a portion of the valve body 30 is movable into
and out of the passageway 28. The valve body 30 is operably
associated with the motor assembly 10 such that actuation of the
motor assembly 10 shifts the valve body 30 within the valve housing
14, as is discussed in more detail below. It is noted that while
the valve body 30 is depicted in FIG. 1 as a piston having a
generally cylindrical shape, the use of other suitable piston
shapes or of valve bodies that are not pistons are both clearly
within the ambit of the present invention. In this way, movement of
the valve body 30 can increase or restrict the allowable flow rate
of a fluid through the conduit 16 between the inlet portion 24 and
the outlet portion 26, as will be readily understood by one of
ordinary skill in the art upon review of this disclosure.
[0025] The conduit 16 may be part of a cooling or refrigeration
system, such that the fluid carried within the conduit 16 is a
refrigerant. Examples of such cooling systems suitable for use with
the motor assembly 10 and the valve assembly 12 described herein
are disclosed in U.S. Pat. No. 6,076,368 ("the '368 patent") and
U.S. Pat. No. 6,272,870 ("the '870 patent"). Both the '368 patent
and the '870 patent, which each have the same assignee of record as
the present application, are hereby incorporated by reference in
their entirety to the extent not inconsistent with the present
disclosure.
[0026] With continued reference to FIG. 1, and turning also to
FIGS. 2-4, the elements and construction of the motor assembly 10
are described in greater detail. As noted above, the motor assembly
10 is connectable to the valve assembly 12 and is operably
associated with the valve body 30 to move the valve body 30 within
the valve assembly 12. In the case of an application of the motor
assembly 10 and the valve assembly 12 within a cooling system, the
motor assembly 10 is operable to control the flow rate of the
cooling fluid through the valve housing 14, and thus through the
conduit 16, in order to regulate temperature associated with such a
cooling system.
[0027] With particular reference to FIG. 3, the motor assembly 10
broadly includes a rotor 32 and a stator 34, with the rotor 32
being rotatable about an axis 36. The motor assembly 10 includes an
isolation housing 38 that is disposed between the rotor 32 and the
stator 34, and within which the rotor 32 is located. The motor
assembly 10 of the depicted embodiment also includes a shaft 40
associated with the rotor 32, as explained in detail below. Similar
to the rotor 32, the shaft 40 is disposed along the axis 36. In
addition, the motor assembly 10 further includes an encapsulating
cover 42 that surrounds the stator 34 and bonds the stator 34 to
the isolation housing 38 to prevent any relative movement
therebetween.
[0028] The rotor 32 of the depicted embodiment comprises a radially
inner core element 44 and a radially outer element 46 radially
surrounding and attached to at least a portion of the core element
44. The core element 44 presents a radially inner periphery 48 that
is generally cylindrical in shape and concentric about the axis 36.
The core element 44 also includes a plurality of axially extending
holes 50 extending therethrough, with each hole 50 being spaced
radially outwardly from the inner periphery 48. The radially inner
periphery 48 of the core element 44 includes a threaded portion 52,
with the threaded portion 52 cooperating with the shaft 40 to
linearly shift the shaft 40 as a result of rotation by the rotor
32, as described in detail below. In one embodiment, the core
element 44 is formed of a synthetic resin material that is
nonmagnetic, although other suitable materials are clearly within
the ambit of the present invention.
[0029] The radially outer element 46 of the rotor 32 radially
surrounds at least a portion of the core element 44 and is spaced
radially outwardly from the plurality of holes 50. The radially
outer element 46 is formed of a magnetic material in order to
cooperate with the stator 34 to produce rotational movement of the
rotor 32. In one embodiment, the magnetic material of the radially
outer element 46 includes neodymium, although other magnetic
materials could alternatively be used, as will be readily
appreciated by one of ordinary skill in the art.
[0030] The isolation housing 38 of the depicted embodiment
comprises a generally cylindrical sleeve portion 54 threadably
connected to a connecting bell portion 56. The sleeve portion 54
defines an internal rotor chamber 58, within which the rotor 32 is
located, and presents first and second axial margins 60, 62. An end
wall 64 radially spans the first axial margin 60 to seal the first
axial margin 60 of the sleeve portion 54 and an end of the rotor
chamber 58. The sleeve portion 54 further presents a radially
outermost surface 66, part of which defines a thin wall portion 68
through which magnetic flux can pass between the rotor 32 and the
stator 34. While the sleeve portion 54 allows magnetic flux to pass
therethrough, the sleeve portion 54 maintains the rotor 32 and the
stator 34 in fluid isolation from one another, as explained in
detail below. In one embodiment, the sleeve portion 54 is formed of
stainless steel, although the use of other suitable materials,
particularly nonmagnetic materials, is clearly within the ambit of
the present invention.
[0031] The radially outermost surface 66 of the sleeve portion 54
is substantially cylindrical and smooth such that the stator 34 can
be positioned around the sleeve portion 54 during construction of
the motor assembly 10. An upstanding ridge 70 extends radially
outwardly from the surface 66 such that the stator 34 is disposed
adjacent the ridge 70 to position the stator 34 in general axial
alignment with the rotor 32, as shown in FIG. 3.
[0032] The second axial margin 62 of the sleeve portion 54 is
substantially open and threadably secured to the bell portion 56,
as described in detail below. A pair of axially extending
depressions 72, 74 extend inwardly from the end wall 64 toward the
rotor chamber 58. The depressions 72, 74 facilitate the use of a
tool, such as a spanner wrench, to rotate the sleeve portion 54
relative to the bell portion 56 to secure the sleeve portion 54 to
the bell portion 56. An axially extending recess 76 is disposed
along the axis 36 and extends outwardly from the rotor chamber 58
toward the end wall 64. The recess 76 is sized to accommodate a
portion of the shaft 40, as explained in detail below.
[0033] The bell portion 56 defines an internal valve body chamber
78, within which the valve body 30 may be located, and presents
first and second axial margins 80, 82. The first axial margin 80 of
the bell portion 56 is threadably secured to the second axial
margin 62 of the sleeve portion 54 to form a junction 84
therebetween. The second axial margin 82 of the bell portion 56 is
connectable to the valve housing 14, as depicted in FIG. 1. In one
embodiment, the bell portion 56 is formed of brass, although other
suitable materials are clearly within the ambit of the present
invention.
[0034] The bell portion 56 also includes radially inwardly
extending wall structure 86 that forms an endshield of the motor
assembly 10 to generally separate the rotor chamber 58 from the
valve body chamber 78. The wall structure 86 also includes a flat
surface 88 adjacent a shaft passage 90 that is aligned with and
spaced generally parallel from the axis 36. The shaft passage 90
allows the shaft 40 to extend axially between the rotor chamber 58
and the valve body chamber 78 and may also permit pressurized fluid
to enter into the rotor chamber 58 from within the valve housing
14, which is in fluid communication with the conduit 16. In this
way, the rotor 32 may be exposed to pressurized fluid of the
system, but the isolation housing 38 keeps the stator 34 (and the
environment) isolated from pressurized fluid.
[0035] Additional components of the illustrated embodiment
contribute to the advantageous operation of the motor assembly 10.
A first rotational bearing 92 is disposed within the rotor chamber
58, positioned between the sleeve portion 54 and a portion of the
rotor core 44. The first bearing 92 is further positioned adjacent
a solid portion of the first margin 60 of the sleeve portion 54,
with a wave spring 94 disposed axially between the first margin 60
and the first bearing 92. The first bearing 92 at least partially
rotationally supports the rotor 32 within the rotor chamber 58. A
second rotational bearing 96 is also disposed within the rotor
chamber 58, but positioned between the bell portion 56 and a
portion of the rotor core 44. The second bearing 96 is further
positioned adjacent the wall structure 86 of the bell portion 56,
and at least partially rotationally supports the rotor 32 within
the rotor chamber 58. It is specifically noted, however, that the
second bearing 96 could optionally be positioned within the sleeve
portion 54 adjacent the second margin 62 thereof in an alternate
embodiment (not shown) without departing from the teachings of the
present invention.
[0036] The shaft 40 is disposed along the axis 36, extending within
both the rotor chamber 58 and the valve body chamber 78, and
presents a radially outer periphery 98. The shaft 40 is linearly
movable along the axis 36 and cooperates with the rotor 32 such
that rotation of the rotor 32 causes the shaft 40 to move linearly
between an extended position and a retracted position. By the
extended position, it is meant that the shaft 40 is disposed as far
as it can be toward the second margin 82 of the bell portion 56. By
the retracted position, it is meant that the shaft 40 is disposed
as far as it can be toward the first margin 60 of the sleeve
portion 54.
[0037] In the depicted embodiment, the outer periphery 98 of the
shaft 40 presents an externally threaded portion 100 that
cooperates with the internally threaded portion 52 of the rotor 32
such that rotation of the rotor 32 causes the shaft 40 to shift
linearly in an axial direction. In addition, the outer periphery 98
of the shaft 40 presents a substantially flat portion 102 that
cooperates with the flat surface 88 of the wall structure 86 of the
bell portion 56 to slide axially therealong and prevent rotation of
the shaft 40. The shaft 40 further presents first and second axial
margins 104, 106, with the second margin 106 being configured for
attachment to the valve body 30.
[0038] It is noted that when the shaft 40 is in the retracted
position, the first margin 104 may be disposed within the shaft
recess 76 of the sleeve portion 54, and the valve body 30 will be
substantially entirely received within the valve body chamber 78 of
the bell portion 56. In this position, fluid flow through the
conduit 16 is at a maximum rate. On the other hand, when the shaft
40 is in the extended position, then the valve body 30 will be
substantially entirely disposed within the valve housing to
substantially restrict fluid flow through the conduit 16.
[0039] Finally, with continued reference to FIG. 3, the
encapsulating cover 42 is described in more detail. As described
briefly above, the cover 42 surrounds the stator 34 to both seal
and bond the stator 34 to the isolation housing 38. In particular,
it is noted that the stator 34 presents an outer circumferential
surface 108 and axial margins 110, 112. The cover 42 both radially
and axially surrounds the stator 34 to overlie the circumferential
surface 108 and both axial margins 110, 112. Furthermore, the bell
portion 56 includes a radially inwardly extending groove 114
extending along the outer circumference of the bell portion 56. The
cover 42 extends into the groove 114 to prevent axial movement of
the stator 34 relative to the isolation housing 38. The cover 42
also overlies the junction 84 between the sleeve portion 54 and the
bell portion 56, thereby preventing any potential leakage of
pressurized fluid from within the isolation housing 38 through the
junction 84.
[0040] As shown in FIGS. 2 and 4, the motor assembly 10 also
includes wiring 116 that connects to the stator 34 to provide power
and control signals to the motor assembly 10. In particular, when
the motor assembly 10 comprises a stepper motor, the wiring 116 may
transmit control signals from a microcontroller (not shown) in
order to precisely affect movement of the rotor 32 and consequently
the shaft 40 and the valve body 30. The encapsulating cover 42
overlies the connection between the wiring 116 and the stator 34,
adding security to this connection against any loosening due to
vibration within the system.
[0041] In one embodiment, the encapsulating cover 42 is formed of a
resin material. In particular, the depicted cover 42 is formed of a
two-part epoxy, although other suitable materials are clearly
within the ambit of the present invention.
[0042] The preferred forms of the invention described above are to
be used as illustration only, and should not be utilized in a
limiting sense in interpreting the scope of the present invention.
Obvious modifications to the exemplary embodiments, as hereinabove
set forth, could be readily made by those skilled in the art
without departing from the spirit of the present invention.
[0043] The inventors hereby state their intent to rely on the
Doctrine of Equivalents to determine and access the reasonably fair
scope of the present invention as pertains to any apparatus not
materially departing from but outside the literal scope of the
invention set forth in the following claims.
* * * * *