U.S. patent application number 11/972095 was filed with the patent office on 2008-08-28 for system and method for detecting ice.
Invention is credited to Terrence J. Knowles, Brian J. Truesdale.
Application Number | 20080202142 11/972095 |
Document ID | / |
Family ID | 39473286 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080202142 |
Kind Code |
A1 |
Knowles; Terrence J. ; et
al. |
August 28, 2008 |
System and Method for Detecting Ice
Abstract
A system for detecting ice of a particular thickness includes a
structure from which ice forms, and an ice detection assembly
movably secured to the structure. The ice detection assembly
includes a transducer operatively connected to a sensing medium.
The transducer generates a trapped acoustic wave in the sensing
medium, wherein ice of a particular thickness is detected when the
ice that forms from the structure contacts the sensing medium and
dampens the trapped acoustic wave within the sensing medium.
Inventors: |
Knowles; Terrence J.;
(Barrington, IL) ; Truesdale; Brian J.; (Buffalo,
IL) |
Correspondence
Address: |
ILLINOIS TOOL WORKS INC.
3600 WEST LAKE AVENUE, PATENT DEPARTMENT
GLENVIEW
IL
60025
US
|
Family ID: |
39473286 |
Appl. No.: |
11/972095 |
Filed: |
January 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60902797 |
Feb 22, 2007 |
|
|
|
Current U.S.
Class: |
62/340 |
Current CPC
Class: |
F25C 5/185 20130101;
F25C 5/08 20130101; G01N 29/225 20130101; G01N 2291/02881 20130101;
F25C 2700/02 20130101; G01N 2291/023 20130101; G01N 2291/0422
20130101; G01N 29/11 20130101; G01N 2291/0251 20130101; F25C 1/22
20130101; B64D 15/20 20130101 |
Class at
Publication: |
62/340 |
International
Class: |
F25C 1/00 20060101
F25C001/00; F25C 1/04 20060101 F25C001/04 |
Claims
1. A system for detecting ice of a particular thickness,
comprising: a structure from which ice forms; and an ice detection
assembly movably secured to said structure, said ice detection
assembly comprising a transducer operatively connected to a sensing
medium, said transducer generating a trapped acoustic wave in said
sensing medium, wherein ice of a particular thickness is detected
when the ice that forms from said structure contacts said sensing
medium and dampens the trapped acoustic wave within said sensing
medium.
2. The system of claim 1, wherein said sensing medium comprises a
substrate having an acoustic wave cavity.
3. The system of claim 1, wherein said sensing medium comprises a
sensor strip.
4. The system of claim 3, further comprising a support plate that
supports said sensor strip, said support plate shielding said
transducer from said structure.
5. The system of claim 1, wherein said sensor strip comprises an
extension beam integrally connected to an ice contacting portion
through a curved intermediate portion.
6. The system of claim 1, further comprising a heating element
configured to heat said sensing medium.
7. The system of claim 1, wherein said structure is an ice grid
having a plurality of ice forming compartments.
8. The system of claim 7, further comprising an ice collection bin,
wherein said ice grid is heated to form ice cubes when the ice
contacts said sensing medium, the ice cubes being collected in said
ice collection bin.
9. The system of claim 1, further comprising a bracket that
pivotally connects said ice detection assembly to said
structure.
10. The system of claim 1, wherein said bracket is configured to
adjustably position said ice detection assembly with respect to
said structure.
11. The system of claim 1, further comprising a control unit
operatively connected to said ice detection assembly.
12. An ice forming system, comprising: an ice grid having a
plurality of forming compartments configured to form ice cubes,
wherein water flows over said ice grid and into said plurality of
forming compartments to form outwardly growing ice; and an ice
detection assembly movably secured to said ice grid, said ice
detection assembly comprising a transducer operatively connected to
a sensing medium, said transducer generating a trapped acoustic
wave in said sensing medium, wherein ice of a particular thickness
is detected when the outwardly growing ice from said ice grid
contacts said sensing medium and dampens the trapped acoustic wave
within said sensing medium.
13. The system of claim 12, wherein said sensing medium comprises a
substrate having an acoustic wave cavity.
14. The system of claim 12, wherein said sensing medium comprises a
sensor strip having an extension beam integrally connected to an
ice contacting portion through a curved intermediate portion.
15. The system of claim 14, further comprising a support plate that
supports said sensor strip, said support plate shielding said
transducer from said ice grid, wherein said ice contacting portion
is exposed to said ice grid.
16. The system of claim 12, further comprising a heating element
configured to heat said sensing medium.
17. The system of claim 12, further comprising a bracket that
pivotally connects said ice detection assembly to said ice grid,
wherein said bracket is configured to adjustably position said ice
detection assembly with respect to said ice grid.
18. An ice forming system, comprising: an ice grid having a
plurality of forming compartments configured to form ice cubes,
wherein water flows over said ice grid and into said plurality of
forming compartments to form outwardly growing ice; an ice
detection assembly pivotally secured to said ice grid, said ice
detection assembly comprising a transducer operatively connected to
a sensing medium, said transducer generating a trapped acoustic
wave in said sensing medium, wherein ice of a particular thickness
is detected when the outwardly growing ice from said ice grid
contacts said sensing medium and dampens the trapped acoustic wave
within said sensing medium; an ice collection bin, wherein said ice
grid is heated to detach the ice cubes from said compartments when
the outwardly growing ice contacts said sensing medium, said ice
detection assembly pivoting away from said ice grid as falling ice
cubes contact said ice detection assembly, the ice cubes being
collected in said ice collection bin; and one or both of a
processing unit and/or a detection circuit operatively connected to
said ice detection assembly.
19. The system of claim 18, wherein said sensing medium comprises a
substrate having an acoustic wave cavity, said acoustic wave cavity
having a greater mass per unit surface area than that of said
substrate adjacent said acoustic wave cavity.
20. The system of claim 18, wherein said sensing medium comprises a
sensor strip having an extension beam integrally connected to an
ice contacting portion through a curved intermediate portion.
21. The system of claim 20, further comprising a support plate that
supports said sensor strip, said support plate shielding said
transducer from said ice grid, wherein said ice contacting portion
is exposed to said ice grid.
22. The system of claim 18, further comprising a heating element
configured to heat said sensing medium.
23. The system of claim 18, further comprising a bracket that
pivotally connects said ice detection assembly to said ice grid,
wherein said bracket is configured to adjustably position said ice
detection assembly with respect to said ice grid.
Description
RELATED APPLICATIONS
[0001] This application relates to and claims priority benefits
from U.S. Provisional Patent Application No. 60/902,797 entitled
"System And Method For Detecting The Presence Of Ice," filed Feb.
22, 2007, which is hereby incorporated by reference in its
entirety.
FIELD OF THE INVENTION
[0002] Embodiments of the present invention generally relate to a
system and method for detecting the presence of ice, and more
particularly to a system and method of detecting the presence and
thickness of ice through the use of trapped acoustic waves.
BACKGROUND OF THE INVENTION
[0003] Typical systems for detecting the presence of ice use
capacitive sensing systems that determine impedance from a sensor
electrode to ground. A conventional ice forming machine includes an
ice grid. As water flows over the grid, the water freezes. With
continued freezing, the layer of ice continues to grow outward.
When the ice layer grows far enough, the water cascading over the
ice layer contacts the capacitive electrode or sensor. If the water
makes continuous contact with the electrode for an extended period
of time, the ice forming machine transitions to a harvest mode and
heats the grid so that the layers of ice break off.
[0004] Conventional ice forming machines, however, are susceptible
to detrimental effects caused by "scale" build-up on the electrode
and/or spurious conducting paths to ground due to contaminants,
fluids and the like.
SUMMARY OF THE INVENTION
[0005] Certain embodiments of the present invention provide a
system for detecting ice of a particular thickness. The system
includes a structure from which ice forms, and an ice detection
assembly movably secured to the structure. The ice detection
assembly includes a transducer operatively connected to a sensing
medium. The transducer generates a trapped acoustic wave in the
sensing medium, wherein ice of a particular thickness is detected
when the ice that forms from the structure contacts the sensing
medium and dampens the trapped acoustic wave within the sensing
medium.
[0006] The sensing medium may include a substrate having an
acoustic wave cavity. Optionally, the sensing medium may include a
sensor strip. A support plate may be used to support the sensor
strip and shield the transducer from the structure. The sensor
strip may include an extension beam integrally connected to an ice
contacting portion through a curved intermediate portion.
[0007] The system may also include a heating element configured to
heat the sensing medium. Additionally, the system may include a
control unit operatively connected to the ice detection
assembly.
[0008] The structure may be an ice grid having a plurality of ice
forming compartments. In this case, the system may also include an
ice collection bin, wherein the ice grid may be heated to form ice
cubes when the ice contacts the sensing medium, thereby breaking
the ice cubes off from the ice grid. The ice cubes then fall into
the ice collection bin.
[0009] The system may also include a bracket that pivotally
connects the ice detection assembly to the structure. The bracket
is configured to adjustably position the ice detection assembly
with respect to the structure.
[0010] Certain embodiments of the present invention provide an ice
forming system that includes an ice grid, an ice detection
assembly, an ice collection bin and one or both of a processing
unit and/or a detection circuit operatively connected to the ice
detection assembly. The ice grid includes a plurality of forming
compartments configured to form ice cubes, wherein water flows over
the ice grid and into the plurality of forming compartments to form
outwardly growing ice.
[0011] The ice detection assembly is pivotally secured to the ice
grid and includes a transducer operatively connected to a sensing
medium. The transducer generates a trapped acoustic wave in the
sensing medium, wherein ice of a particular thickness is detected
when the outwardly growing ice from the ice grid contacts the
sensing medium and dampens the trapped acoustic wave within the
sensing medium.
[0012] The ice grid may be heated to detach the ice cubes from the
compartments when the outwardly growing ice contacts the sensing
medium. The ice detection assembly pivots away from the ice grid as
falling ice cubes contact the ice detection assembly. The ice cubes
are then collected in the ice collection bin.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0013] FIG. 1 illustrates an isometric view of an ice forming
system according to an embodiment of the present invention.
[0014] FIG. 2 illustrates a simplified lateral view of an ice
forming system according to an embodiment of the present
invention.
[0015] FIG. 3 illustrates an isometric view of an ice detection
assembly according to an embodiment of the present invention.
[0016] FIG. 4 illustrates a rear view of an ice detection assembly
according to an embodiment of the present invention.
[0017] FIG. 5 illustrates a lateral view of an ice detection
assembly according to an embodiment of the present invention.
[0018] FIG. 6 illustrates a front view of an ice detection assembly
according to an embodiment of the present invention.
[0019] FIG. 7 illustrates a simplified lateral view of an ice
forming system according to an embodiment of the present
invention.
[0020] Before the embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of the components set forth in the following description or
illustrated in the drawings. The invention is capable of other
embodiments and of being practiced or being carried out in various
ways. Also, it is to be understood that the phraseology and
terminology used herein are for the purpose of description and
should not be regarded as limiting. The use of "including" and
"comprising" and variations thereof is meant to encompass the items
listed thereafter and equivalents thereof as well as additional
items and equivalents thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 1 illustrates an isometric view of an ice forming
system 10 according to an embodiment of the present invention. The
ice forming system 10 includes an ice grid 12, an ice detection
assembly 14 and an ice collection bin 16. The ice grid 12 and the
ice detection assembly 14 are connected to a source of power (not
shown). Additionally, the ice detection assembly 14 and the ice
grid 12 may also be in electrical communication with a control
system, such as a processing unit (not shown in FIG. 1).
[0022] The ice grid 12 includes a main housing 18 having a top
surface 20 integrally connected to side walls (not shown in FIG.
1), which are, in turn, integrally connected to a base (not shown
in FIG. 1). An ice forming chamber 22 is defined between the top
surface 20, the side walls and the base. A plurality of forming
compartments 24 are positioned with the ice forming chamber 22. The
plurality of forming compartments 24 are configured to form ice
cubes.
[0023] The ice detection assembly 14 includes a deflection arm 26
pivotally connected to the top surface 20 of the ice grid 12
through a bracket 28. The deflection arm 26 is configured to pivot
in the directions of arrows A and A' about an axis defined by rods
30 that secure the deflection arm 26 to the bracket 28. A sensor
housing 31 having a transducer 32 operatively connected to an
acoustic wave cavity 34 is secured to the deflection arm 26. The
transducer 32 and acoustic wave cavity 34 may be distally located
from the deflection arm 26, as shown in FIG. 1. The transducer 32
is on one side of the acoustic wave cavity 34, the other side of
which is exposed to water and ice proximate the ice grid 12. The
transducer 32 is electrically connected to the source of power.
[0024] In operation, water cascades over the ice forming chamber 22
and into the individual compartments 24. As the ice grid 12 cools,
the water collected within the ice compartments 24 freezes and
grows outwardly towards the ice detection assembly 14. As discussed
below, the ice detection assembly 14 senses when the ice bonds to
the acoustic wave cavity 34, at which point the cooling process
stops and an ice harvest mode begins. In particular, the ice grid
12 may be heated to break the ice off from the compartments 24. As
the ice breaks off, the ice may hit the deflection arm 26 as it
falls toward the collection bin 16. As the ice hits the deflection
arm 26, the deflection arm 26 is pushed back in the direction of
arrow A' so that the ice falls into the collection bin 16.
[0025] FIG. 2 illustrates a simplified lateral view of the ice
forming system 10 according to an embodiment of the present
invention. As noted above, the ice detection assembly 14 includes
the transducer 32 operatively connected to a rear of the acoustic
wave cavity 34. The ice detection assembly 14 utilizes one or more
acoustic waves trapped in the acoustic wave cavity 34 to detect the
presence of ice on the outer surface 36 of the acoustic wave cavity
34. To detect the presence of ice, a trapped acoustic wave, such as
a trapped shear acoustic wave, is generated within the acoustic
wave cavity 34 by the transducer 32, as described in U.S. Pat. No.
7,026,943, entitled "Acoustic Wave Ice and Water Detector," which
is hereby incorporated by reference in its entirety.
[0026] As shown in FIG. 2, the acoustic wave cavity 34 is defined
by a raised area 38 of a substrate 40. The acoustic wave cavity 34
is formed on the substrate 40 by an area of increased mass such
that the mass per unit surface area of the acoustic wave cavity 34
is greater than the mass per unit surface area of the substrate 40
immediately adjacent the acoustic wave cavity 34. The acoustic wave
cavity 34 may also be defined by an area of increased mass that is
not raised above the substrate 40. Such cavities may be formed, for
example, by depositing a thin layer of material on the surface of
the substrate 40 in an area defining the acoustic wave cavity 34.
Such cavities may also be formed with material of greater mass than
the substrate 40 throughout the cavity or in a portion thereof.
[0027] The raised area 38 defining the acoustic wave cavity 34 may
be square, rectangular or other shapes. The raised area 38 may have
a circular circumference or peripheral edge. The raised area 38 may
have a flat surface or may have a curved, dome-like surface, as
shown in FIG. 2.
[0028] The height and geometry of the acoustic wave cavity 34 that
will support a trapped or resonant acoustic wave is the same as the
height and geometry requirements of an acoustic wave cavity
supporting a trapped shear wave as described in U.S. Pat. No.
7,106,310, entitled "Acoustic Wave Touch Actuated Switch," which is
hereby incorporated by reference in its entirety.
[0029] Embodiments of the present invention use the transducer 32
to generate a trapped resonant acoustic wave within the acoustic
wave cavity 34, as described in U.S. Pat. No. 7,026,943. The
transducer 32 is electrically connected to a processing unit 41.
When no ice contacts the raised area 38 of the acoustic wave cavity
34, a known amplitude, impedance or decay rate of a trapped
acoustic wave cavity is sensed by the processing unit 41 (or
detection circuit 42). Thus, the processing unit (or detection
circuit 42) determines that no ice is contacting the acoustic wave
cavity 34. When ice contacts the acoustic wave cavity 34, however,
the sensed amplitude, impedance or decay rate changes. That is,
when the ice 44 contacts the acoustic wave cavity 34, the acoustic
energy trapped in the acoustic wave cavity 34 is dampened. As such,
the processing unit 41 or detection circuit 42 is able to determine
that ice is bonding to the acoustic wave cavity 34.
[0030] When the processing unit 41 or detection circuit 42
determines that ice is contacting the acoustic wave cavity 34, the
processing unit 41 may transition the ice grid 12 into a heating
mode, in which the compartments 24 may be heated in order to break
off the formed ice 44 protruding therefrom. As the ice breaks off
from the compartments 24, the ice falls into the collection bin 16.
As noted above, ice that hits the ice detection assembly 14 forces
it to swing backward in the direction of A'. As such, ice above the
ice detection assembly 14 is allowed to fall into the collection
bin 16.
[0031] The ice detection assembly 14 may also include a heating
element 43, such as a coil heater, operatively connected to a rear
surface of the substrate 40. The heating element 43 may be used to
slightly heat the acoustic wave cavity 34 so that water
condensation does not freeze on the acoustic wave cavity 34.
Condensation that freezes to ice could produce an ice detection
reading (i.e. the processing unit 41 or detection circuit 40 may
detect the presence of ice through a change in amplitude, impedance
or decay rate of a trapped acoustic wave) before the growing ice 44
from the compartments 24 contacts the acoustic wave cavity 34.
[0032] The ice detection assembly 14 may be spaced from the ice
grid 12 at a desired distance, depending on the size of ice to be
formed. As such, the system 10 is able to determine a desired
thickness of ice. That is, when the ice contacts the acoustic wave
cavity 34, the processing unit 41 or detector circuit 42 determines
that ice of a particular thickness (as determined by the spacing of
the detection assembly 14 from the ice grid 12) has formed. If
larger chunks of ice are desired, the ice detection assembly 14 may
be moved away from the ice grid 12. If smaller chunks of ice are
desired, the ice detection assembly 14 may be moved closer to the
ice grid 12. The bracket 28 may be adjustable through directions
denoted by arrows B and B'. For example, the bracket 28 may include
a telescoping neck 46 that allows it to move through the directions
B and B'.
[0033] As shown in FIG. 2, the transducer 32 may be in close
proximity to the ice 44 and flowing water over the ice grid 12.
Thus, the transducer 32 and associated electronics may be sealed to
prevent adverse effects that may arise from water contacting
electronic components. A sealing compound may be applied over the
transducer 32 and associated electronics to prevent water ingress.
Moreover, the transducer 32 and the acoustic wave substrate 40 may
be integrally formed and connected to one another, thereby
providing an improved seal therebetween.
[0034] FIGS. 3 and 4 illustrate isometric and rear views,
respectively, of an ice detection assembly 50 according to an
embodiment of the present invention. The ice detection assembly 50
includes a planar support plate 52 having upturned lateral walls
54. The plate 52 may be formed of plastic. Pivoting rods 56 are
located at proximal ends of the lateral walls 54 and allow the ice
detection assembly 50 to be pivotally attached to a bracket of an
ice grid.
[0035] The support plate 52 securely supports a sensor strip 58,
which may be formed of metal. One end of the sensor strip 58 is
secured to the plate 52 proximate a top portion of the plate 52.
The secured end of the sensor strip 58 is connected to a transducer
60. That is, the transducer 60 is operatively connected to an end
of the sensor strip 58 to produce a trapped acoustic wave within
the sensor strip 58. The sensor strip 58 includes an extension beam
62 that extends from the transducer 60 over a length of the plate
52. That is, the extension beam 62 is part of the sensor strip 58,
itself. The extension beam 62 of the sensor strip 58 may be secured
in place by one or more securing clips 64 that extend from the
plate 52. For example, the securing clips 64 may snapably secure to
edges of the extension beam 62 of the sensor strip 58. An ice
contacting hook 66 extends from the extension beam 62 past the
lower edge of the plate 52. While the extension beam 62 is
generally coplanar with the planar portion 67 of the plate 52, the
hook 66 extends inwardly past the plane 67 of the plate 52. The
sensor strip 58 may be, for example, a 5'' long, 0.4'' wide and 35
mm thick strip of stainless steel operating in shear mode at 1.2
MHz.
[0036] FIG. 5 illustrates a lateral view of the ice detection
assembly 50. As shown in FIG. 5, the hook 66 curves inwardly in the
direction of arrow C from the extension beam 62. A flattened ice
contacting portion 68 of the hook 66 is connected to an inwardly
curved portion 70 extending from the extension beam 62. An upturned
tip 72 is, in turn, integrally connected to the flattened ice
contacting portion 68. The plane x of the flattened ice contacting
portion 68 is inwardly-offset in the direction of arrow C from the
plane y of the extension beam 62. As shown in FIG. 5, the flattened
ice contacting portion 68 extends past the plate 52 in the
direction of arrow C.
[0037] FIG. 6 illustrates a front view of the ice detection
assembly 50 according to an embodiment of the present invention.
The plate 52 provides a shield that protects the transducer 60
(shown, e.g., in FIG. 5) from direct contact with ice and
water.
[0038] FIG. 7 illustrates a simplified lateral view of an ice
forming system 80 according to an embodiment of the present
invention. The ice forming system 80 includes the ice detection
assembly 50 pivotally connected to an ice grid 82 through a bracket
84, and operates similar to the ice forming system 10 shown and
described in FIGS. 1 and 2. In particular, water 86 flows over the
ice grid 82 to form ice 88 that grows and eventually contacts the
ice contacting portion 68 of the hook 66. The transducer 60 is
connected to a processing unit, which detects changes in amplitude,
impedance, wave decay rate or the like. That is, the processing
unit (or detecting circuit) detects when ice contacts the ice
contacting portion 68 and transitions the system 80 to an ice
harvesting mode, as discussed above with respect to FIGS. 1 and
2.
[0039] Referring to FIGS. 3-7, it has been found that the sensor
strip 58, which may alternatively be a tube or rod, is an efficient
medium for propagating certain types of acoustic waves. The
transducer 60 generates an acoustic wave within the sensor strip 58
that travels all the way to the hook 66, reflecting back and forth,
and which is confined by the sides and ends of the sensor strip 58.
That is, the generated acoustic wave is trapped within the sensor
strip 58. It has been discovered that confined or trapped shear
waves within the sensor strip 58 (and by extension, torsional waves
in rods and tubes) may be significantly absorbed by ice bonded to
the ice contacting portion 68, as opposed to the length of the
sensor strip 58. Water flowing on the sides of the sensor strip 58
does not materially absorb wave energy. As such, the system 10 is
able to discriminate between the presence of water and ice.
Moreover, the sensor strip 58 is insensitive to mineral deposits
(scale), in stark contrast to conventional sensing devices.
[0040] The sensor strip 58 is long enough to displace the
transducer 60 and associated electronics out of the path of the
water 86. As such, the water 86 is not able to infiltrate the
transducer 60 or the associated electronics, thereby alleviating a
need to provide additional sealing. The sensor strip 58 is easier
to manufacture than conventional ice sensing devices. In general,
it has been found that the sensor strip 58 may be bent, twisted and
folded in various shapes without affecting performance. In general,
the curvature radii of the sensor strip 58 are large in relation
acoustic wavelengths of generated waves within the sensor strip
58.
[0041] Embodiments of the present invention sense and detect the
presence and thickness of ice through acoustic waves, particularly
trapped acoustic waves within an acoustic wave cavity. It has been
found that embodiments of the present invention, in stark contrast
to conventional ice forming machines, are not affected by scale
build up (presumably because the wave motion couples through the
calcium carbonate (scale) layer), water and other contaminants.
[0042] Embodiments of the present invention do not use propagating
waves. Instead, embodiments of the present invention utilize
trapped wave motion, as described in U.S. Pat. No. 7,106,310 and
U.S. Pat. No. 7,026,943. Detecting ice through trapped wave motion
provides a detection system that is more sensitive to the presence
of ice and greatly simplifies signal processing. Plastic acoustic
wave sensing systems may be advantageous over metal acoustic wave
sensing systems because their thermal conductivity is less than
typical metals, which allows for better thermal insulation from the
ice generating surfaces.
[0043] Embodiments of the present invention may be used in various
settings and applications. The ice cube forming devices described
above are just examples. Embodiments of the present invention may
also be used to detect the presence and thickness of ice forming on
condensation coils and pipes, which is a known problem for
refrigeration units, and, for example, to determine the ice
build-up on the outer surfaces of skyscrapers, which may pose
safety hazards (e.g., falling ice from skyscrapers hitting
pedestrians).
[0044] While various spatial and directional terms, such as upper,
bottom, lower, mid, lateral, horizontal, vertical, and the like may
used to describe embodiments of the present invention, it is
understood that such terms are merely used with respect to the
orientations shown in the drawings. The orientations may be
inverted, rotated, or otherwise changed, such that an upper portion
is a lower portion, and vice versa, horizontal becomes vertical,
and the like.
[0045] Variations and modifications of the foregoing are within the
scope of the present invention. It is understood that the invention
disclosed and defined herein extends to all alternative
combinations of two or more of the individual features mentioned or
evident from the text and/or drawings. All of these different
combinations constitute various alternative aspects of the present
invention. The embodiments described herein explain the best modes
known for practicing the invention and will enable others skilled
in the art to utilize the invention. The claims are to be construed
to include alternative embodiments to the extent permitted by the
prior art.
[0046] Various features of the invention are set forth in the
following claims.
* * * * *