U.S. patent application number 11/063652 was filed with the patent office on 2005-09-15 for active seal assemblies for movable windows.
Invention is credited to Barvosa-Carter, William, Browne, Alan L., Henry, Christopher P., Herrera, Guillermo A., Johnson, Nancy L., Keefe, Andrew C., Mc Knight, Geoffrey P..
Application Number | 20050198904 11/063652 |
Document ID | / |
Family ID | 34994186 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050198904 |
Kind Code |
A1 |
Browne, Alan L. ; et
al. |
September 15, 2005 |
Active seal assemblies for movable windows
Abstract
Active seal assemblies employing active materials that can be
controlled and remotely changed to alter the seal effectiveness,
wherein the active seal assemblies actively change modulus
properties such as stiffness, shape orientation, and the like. In
this manner, in seal applications such as a vehicle window
application, the seal force can be selectively reduced during
movement of the window and increased when the window is stationary,
thereby selectively changing seal effectiveness. Active materials
refers to several different classes of materials all of which
exhibit a change in at least one attribute such as dimension,
shape, and/or flexural modulus when subjected to at least one of
many different types of applied activation signals, examples of
such signals being thermal, electrical, magnetic, stress, and the
like.
Inventors: |
Browne, Alan L.; (Grosse
Pointe, MI) ; Johnson, Nancy L.; (Northville, MI)
; Barvosa-Carter, William; (Ventura, CA) ; Mc
Knight, Geoffrey P.; (Los Angeles, CA) ; Keefe,
Andrew C.; (Santa Monica, CA) ; Henry, Christopher
P.; (Newbury Park, CA) ; Herrera, Guillermo A.;
(Winnetka, CA) |
Correspondence
Address: |
KATHRYN A. MARRA
General Motors Corporation
Legal Staff, Mail Code 482-C23-B21
P.O. Box 300
Detroit
MI
48265-3000
US
|
Family ID: |
34994186 |
Appl. No.: |
11/063652 |
Filed: |
February 23, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60552781 |
Mar 12, 2004 |
|
|
|
Current U.S.
Class: |
49/374 |
Current CPC
Class: |
F16J 15/028 20130101;
F16J 15/0806 20130101; Y10S 292/65 20130101; E05Y 2201/43 20130101;
Y10S 277/921 20130101; B60J 10/16 20160201; B60J 10/244 20160201;
C08L 2201/12 20130101; E05C 19/001 20130101; F16J 15/061 20130101;
B60J 10/50 20160201; E05B 47/0009 20130101; B60J 10/15 20160201;
E05Y 2400/614 20130101; E06B 7/2314 20130101; F16J 15/064 20130101;
E05B 81/20 20130101; E05B 15/16 20130101; E05Y 2900/531 20130101;
E05B 81/00 20130101; F16J 15/027 20130101; F16J 15/025 20130101;
Y10T 16/56 20150115; E05F 1/00 20130101; E05C 19/166 20130101; E05Y
2900/55 20130101; E05B 15/1607 20130101; E05Y 2800/67 20130101;
B60J 10/40 20160201; F16J 15/022 20130101; E05B 47/0011 20130101;
Y10T 292/11 20150401 |
Class at
Publication: |
049/374 |
International
Class: |
E05F 011/38 |
Claims
1. A vehicle window system, comprising: a movable window slidably
disposed within a stationary frame; a seal assembly in sealing
communication with the movable window, the seal assembly comprising
a active material operative to change at least one attribute in
response to an activation signal, wherein a seal force of the seal
assembly against the window changes with a change in the at least
one attribute of the active material; an activation device in
operative communication with the active material; and a controller
in operative communication with the activation device.
2. The vehicle window system of claim 1, wherein the active
material comprises a shape memory alloy, a shape memory polymer, a
ferromagnetic shape memory alloy, an electroactive polymer, an
electrorheological fluid, a magnetorheological elastomer, a
dielectric elastomer, a magnetorheological fluid, piezoelectric
material, an ionic polymer metal composite, or combinations
comprising at least one of the foregoing materials.
3. The vehicle window system of claim 1, wherein the active
material forms an actuator, wherein the actuator is external to the
seal assembly.
4. The vehicle window system of claim 1, wherein the movable window
is in operative communication with a motor.
5. The vehicle window system of claim 1, wherein the movable window
is in operative communication with a hand crank.
6. The vehicle window system of claim 1, wherein the seal assembly
comprises a plurality of strips and/or wires of the active material
embedded within a seal structure.
7. The vehicle window system of claim 1, wherein the seal assembly
has a cross sectional area that selectively decreases or increases
in response to the activation signal.
8. The vehicle window system of claim 1, wherein the seal assembly
comprises an exoskeleton formed of the active material and a seal
membrane.
9. The vehicle window system of claim 1, wherein the activation
signal comprises a thermal activation signal, a magnetic activation
signal, an electrical activation signal, chemical activation
signal, or a combination comprising at least one of the foregoing
signals.
10. The vehicle window system of claim 1, wherein the seal assembly
comprises the active material and a flexible seal structure.
11. The vehicle window system of claim 1, wherein the seal assembly
consists of the active material.
12. The vehicle window system of claim 1, wherein the stationary
frame is a door frame.
13. The vehicle window system of claim 1, wherein the active
material is in translational communication with a flexible seal
structure abutting the movable window, wherein the change in the at
least one attribute of the active material increases or decreases
the seal force of the flexible seal structure against the movable
window.
14. A process for operating a vehicle window system, the process
comprising: disposing a seal assembly in sealing communication with
a movable window, wherein the seal assembly comprises an active
material operative to change at least one attribute in response to
an activation signal, wherein a seal force of the seal assembly
against the window changes with the change in the at least one
attribute of the active material; simultaneously moving the window
and reducing the seal force by activating the active material; and
increasing the seal force when the window is stationary by
discontinuing the activation signal to the active material.
15. The process of claim 14, wherein the active material comprises
a shape memory alloy, a shape memory polymer, a ferromagnetic shape
memory alloy, an electroactive polymer, an electrorheological
fluid, a magnetorheological elastomer, a dielectric elastomer, a
magnetorheological fluid, piezoelectric material, an ionic polymer
metal composite, or combinations comprising at least one of the
foregoing materials.
16. The process of claim 14, wherein the activation signal
comprises a thermal activation signal, a magnetic activation
signal, an electrical activation signal, chemical activation
signal, or a combination comprising at least one of the foregoing
signals.
17. The process of claim 14, wherein the active material forms an
actuator, wherein the actuator is external to the seal
structure.
18. The process of claim 14, wherein the seal assembly consists of
the active material.
19. The process of claim 14, wherein reducing the seal force
comprises reducing a cross sectional area of the seal assembly.
20. The process of claim 14, wherein the seal assembly comprises a
plurality of strips and/or wires of the active material embedded
within a seal structure.
21. A vehicle window system, comprising: a movable window slidably
disposed within a stationary frame; a seal assembly in sealing
communication with the movable window, the seal assembly comprising
a seal structure and an active fluid disposed within the seal
structure, wherein the active fluid is operative to change at least
one attribute in response to an activation signal, wherein a seal
force of the seal assembly against the window changes with the
change in the at least one attribute of the active material; an
activation device in operative communication with the active fluid;
and a controller in operative communication with the activation
device.
22. The vehicle window system of claim 21, wherein the active fluid
comprises an electroactive gel, or a magnetorheological fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application relates to and claims priority to
U.S. Provisional Application No. 60/552,781 entitled "Active Seal
Assemblies" and filed on Mar. 12, 2004, the disclosure of which is
incorporated by reference herein in their entirety.
BACKGROUND
[0002] This disclosure generally relates to seals and more
particularly, to active seal assemblies that interface with a
slidable closure member such as a movable automotive window.
[0003] Current methods and assemblies for sealing opposing surfaces
such as movable windows, for example, include the use of flexible
elastic membranes and structures that sealingly compress against an
abutting surface. Typical materials include various forms of
elastomers, e.g., foams and solids, that are formed into structures
having solid and/or hollow cross sectional structures. The
geometries of the cross sections are varied and may range from
circular forms to irregular forms having multiple slots and
extending vanes. Current seals utilized for sealing opposing
surfaces such as the movable window noted above are generally
passive. That is, other than innate changes in modulus of the seal
material due to environmental stimuli, the stiffness and cross
sectional geometries of the seal assemblies cannot be changed or
controlled remotely. Because of this, the seal force applied
against the window during movement is generally the same when the
window is stationary. Consequently, to effect movement of the
window, drag forces must be overcome and compensated for in terms
of motor design for the movable window.
[0004] Another problem with current seals is the tradeoff in seal
effectiveness. Increasing the interface pressure and/or area of the
seal can generally increase seal effectiveness. In automotive
applications, such as the movable window, the increased interface
pressure and/or area of the seal can affect the magnitude of forces
required to effect opening and closure of the window.
[0005] Accordingly, it is desirable to have active seal assemblies
for movable windows that can be controlled and remotely changed to
alter the seal effectiveness, wherein the active seal assemblies
actively change modulus properties. In this manner, window opening
and closing efforts can be minimized yet seal effectiveness can be
maximized when the window is stationary.
BRIEF SUMMARY
[0006] Disclosed herein are active seal assemblies and methods of
use for automotive window systems. In one embodiment, the window
system comprises a movable window slidably disposed within a
stationary frame; a seal assembly in sealing communication with the
movable window, the seal assembly comprising a active material
operative to change at least one attribute in response to an
activation signal, wherein a seal force of the seal assembly
against the window changes with a change in at least one attribute
of the active material; an activation device in operative
communication with the active material; and a controller in
operative communication with the activation device.
[0007] In another embodiment, a vehicle window system comprises a
movable window slidably disposed within a stationary frame; a seal
assembly in sealing communication with the movable window, the seal
assembly comprising a seal structure, and a active fluid disposed
within the seal structure, wherein the active fluid is operative to
change at least one attribute in response to an activation signal,
wherein a seal force of the seal assembly against the window
changes with the change in the at least one attribute of the active
material; an activation device in operative communication with the
active fluid; and a controller in operative communication with the
activation device.
[0008] A process for operating a vehicle window system comprises
disposing a seal assembly in sealing communication with a movable
window, wherein the seal assembly comprises a active material
operative to change at least one attribute in response to an
activation signal, wherein a seal force of the seal assembly
against the window changes with the change in the at least one
attribute of the active material; simultaneously moving the window
and reducing the seal force by activating the active material; and
increasing the seal force when the window is stationary by
discontinuing the activation signal to the active material.
[0009] The above described and other features are exemplified by
the following figures and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Referring now to the figures, which are exemplary
embodiments and wherein like elements are numbered alike:
[0011] FIG. 1 illustrates an exploded view of an exemplary vehicle
door and window suitable for use with an active seal assembly in
accordance with the present disclosure;
[0012] FIG. 2 illustrates a sectional top down view of an active
seal assembly in sealing communication with the window taken along
lines 2-2 of FIG. 1;
[0013] FIG. 3 illustrates a cross sectional view of the active seal
assembly of FIG. 2;
[0014] FIG. 4 illustrates a partial cross sectional view of an
active seal assembly disposed within the vehicle door of FIG. 1 in
accordance with another embodiment;
[0015] FIG. 5 illustrates a cross sectional view of an active seal
assembly in accordance with another embodiment;
[0016] FIG. 6 illustrates a cross sectional view of an active seal
assembly in accordance with another embodiment;
[0017] FIGS. 7-8 illustrate expanded and contracted sectional views
of an active seal assembly in accordance with another
embodiment;
[0018] FIGS. 9-10 illustrate expanded and contracted cross
sectional views of an active seal assembly in accordance with
another embodiment; and
[0019] FIG. 11 illustrates a cross sectional view of an active seal
assembly in accordance with another embodiment.
DETAILED DESCRIPTION
[0020] Disclosed herein are active sealing assemblies and methods
of use, wherein the shape and/or modulus properties of the active
seals employed in the active sealing assemblies can be remotely
activated and/or controlled to selectively provide increased seal
effectiveness. For automotive window applications, the active seal
assemblies are programmed to provide minimal window opening and
closing efforts in addition to providing increased seal
effectiveness when the window is stationary. By controlling seal
effectiveness by active manipulation of the seal properties, seal
force can be selectively increased when the window is stationary
and selectively decreased when the window is moving. As such, a
smaller motor can be used to power movement of the window because
the motor has less drag forces to overcome during window movement.
Moreover, when the window is stationary, the seal force can be
selectively maximized so as to advantageously reduce wind noise as
well as prevent leaking of water, air pollution, and the like,
through the interface provided between the seal and the window.
[0021] Although reference will be made herein to automotive
applications, it is contemplated that the active seal assemblies
can be employed for sealing opposing surfaces for various
non-automotive interfaces between opposing surfaces such as sliding
doors, windows, drawers, and the like. For automotive applications,
the active sealing assemblies are preferably utilized between an
opening in a vehicle and a surface in sliding or sealing engagement
with the opening such as a power window, a sunroof, a side
passenger sliding door, and the like.
[0022] The active sealing assemblies generally comprise an active
material adapted to provide sealing engagement between two opposing
surfaces, an activation device in operative communication with the
active material, and a controller in operative communication with
the activation device for providing an activation signal to the
active material. As will be described in greater detail below, the
term "active material" as used herein refers to several different
classes of materials all of which exhibit a change in at least one
attribute such as dimension, shape, and/or flexural modulus when
subjected to at least one of many different types of applied
activation signals, examples of such signals being thermal,
electrical, magnetic, stress, and the like. One class of active
materials is shape memory materials. These exhibit a shape memory.
Specifically, after being deformed pseudoplastically, they can be
restored to their original shape by the application of the
appropriate field. In this manner, active materials can change to
the trained shape in response to an activation signal. Suitable
shape memory materials include, without limitation, shape memory
alloys (SMA), ferromagnetic SMAs, and shape memory polymers (SMP).
A second class of active materials can be considered as those that
exhibit a change in at least one attribute when subjected to an
applied field but revert back to their original state upon removal
of the applied field. Active materials in this category include,
but are not limited to, piezoelectric materials, electroactive
polymers (EAP), dielectric elastomers, ionic polymer metal
composites (IPMC), magnetorheological fluids and elastomers (MR),
electrorheological fluids (ER), composites of one or more of the
foregoing materials with non-active materials, combinations
comprising at least one of the foregoing materials, and the like.
Depending on the particular active material, the activation signal
can take the form of, without limitation, an electric current, a
temperature change, a magnetic field, a mechanical loading or
stressing, or the like.
[0023] The active material may be integrated within the seal
assembly, may define the complete active seal assembly or may
provide actuation of a seal assembly. Moreover, sealing can be
effected by means of modulus changes, shape changes, combinations
of modulus changes and shape changes, and the like. Of the above
noted materials, SMAs and SMPs based sealing assemblies may further
include a return mechanism to restore the original geometry of the
sealing assembly, if desired. The use of a return mechanism will
depend on the configuration of the seal assembly. The return
mechanism can be mechanical, pneumatic, hydraulic, and/or may be
based on one of the aforementioned active materials.
[0024] In those applications where the active materials are
integrated into a seal assembly structure, the materials integrated
with the active materials are preferably those materials already
utilized for manufacture of seals. For example, various rubbers,
foams, elastomers, and the like can be utilized in combination with
the active material to provide an active sealing assembly. As such,
suitable seal materials are generally flexible and may include, but
are not intended to be limited to, styrene butadiene rubber,
polyurethanes, polyisoprene, neoprene, chlorosulfonated
polystyrenes, and the like.
[0025] By utilizing the active material in the seal assembly, the
seal assembly can reversibly change its modulus and/or shape
properties to provide improved sealing engagement between opposing
surfaces as well as provide minimal effort during window opening
and closing. Applying an activation signal to the active material
can effect the reversible change. Suitable activation signals will
depend on the type of active material. As such, the activation
signal provided for reversibly changing the shape and/or modulus
properties of the seal assembly may include a heat signal, an
electrical signal, a magnetic signal, and combinations comprising
at least one of the foregoing signals, and the like.
[0026] Optionally, the sealing structure may include one or more
sensors that are used in combination with enhanced control logic
to, for example, maintain the same level of sealing force
independent of environmental conditions, e.g., humidity,
temperature, pressure differential between interior and
environment, and the like.
[0027] As will be discussed in greater detail below, the active
materials in the various embodiments disclosed herein can be used
to fabricate the entire seal structure or a portion thereof; can be
configured to externally control the seal structure, e.g., provide
actuator means; can provide an exoskeleton of the seal structure;
and/or can be configured to internally control the seal structure,
e.g., provide the skeletal structure of the seal structure. The
active materials permit the remote and automatic control of the
sealing function and provide enhancements in sealing functionality
through software modifications as opposed to hardware changes. For
example, in the case of automotive windows, control logic can be
utilized to active the active material, e.g., selectively decrease
the cross sectional shape and/or modulus properties of the seal
assembly upon activation of a motor to effect movement of the
window, for example. In this manner, window movement can be made
with minimal effort or resistance as contributed by forces normally
associated with passive seal assemblies.
[0028] Turning now to FIG. 1, there is shown a perspective view of
a vehicle door 10 that utilizes an active seal assembly, wherein an
active material forms the entire seal structure. The vehicle door
10 generally includes a doorframe 12 comprising a slot opening 16
defined by surfaces 18 and 20 that is adapted to guide a movable
window 14 disposed therein. The movable window 14 is in operative
communication with a window motor (not shown) for controlling
window movement within the opening 16. Alternatively, a hand crank
mechanism (not shown) can be utilized, if desired. As shown more
clearly in FIGS. 2 and 3, sealingly abutting the window 14 is an
active seal assembly generally designated by reference numeral
22).
[0029] The active seal assembly 22 is disposed on at least one of
the stationary door surfaces 18 and/or 20 to provide a means for
selectively adjusting the sealing force applied against the window
14. Adjustment of the sealing force can occur by means of selective
modulus changes and/or selective shape changes to the active seal
assembly 22. By way of example, in one embodiment, a active
material is in the form of a tube adapted to selectively expand
from a first shape orientation 24 (shown as a dotted line) to a
second shape orientation 26 (shown as a solid line). The active
material is in operative communication with an activation device
(not shown) and with a controller (not shown), which then
selectively changes the modulus and/or shape of the active seal
assembly 22 under pre-programmed conditions defined by an
algorithm, look-up table, or the like. In this manner, the seal
assembly 22 can be programmed to selectively expand so as to
sealingly abut the window surface 14 when the window is stationary.
In contrast, during actuation of the motor to effect movement of
the window 14, the active material can be activated so as to
provide a change in flexural modulus properties and/or shape
orientation to the seal assembly 22. As such, a reduction in the
seal force applied against the window surface can be programmed,
thereby reducing the frictional forces normally associated during
window movement with passive sealing assemblies.
[0030] By way of example, a tubular seal assembly is constructed of
a dielectric elastomer. Maxwell-related stresses are generated in a
compliant dielectric material by means of a voltage difference
applied to the outer and inner compliant electrodes. Generated
stress causes an increase in surface area of the dielectric
material. By constraining the length of the tube, the radius of the
tube selectively increases. A bias pressure determines the
equilibrium radius of the tube and activation position. An internal
pressure is preferably maintained within the tubular dielectric
elastomer for certain modes of operation. An external pressure is
preferably maintained outside the tubular dielectric material for
other modes of operation. The equilibrium position preferably
requires no activation. Whereas, time in the activated position is
preferably kept to a minimum.
[0031] In another embodiment as shown in FIG. 4, the active seal
assembly 30 is in the form of a blade extending from a stationary
surface 18 and/or 20 tangentially against the window surface 14.
The blade 30 is formed of the active material and exerts a sealing
force against the window surface 14, wherein a change in the
modulus properties of the blade portion 30 can be utilized to
change the sealing force against the window surface 14. For
example, when the window 14 is moving, the seal assembly 22 can be
activated such that the flexural modulus properties for the blade
portion 30 selectively decreases so as to reduce the sealing force
against the window surface 14, i.e., activation of the active
material flexes the blade portion 30. When the window 14 is
stationary, the activation signal can be discontinued so as to
increase the flexural modulus properties of the blade portion 30,
i.e., activation of the active material decreases the flexibility
of the blade portion 30. The decrease in flexural modulus
properties can provide reduced power requirements for window
motion.
[0032] Several different approaches can be considered when using
this type of sealing. In one embodiment, activating the active
material component activates the blade 30 to increase the seal
force. The seal so formed will then be configured to be active when
the power is applied to the active material. In another embodiment,
the sealed position is achieved when power to the active material
component is withheld. The seal is then "pulled back" when power is
applied to the active material component. Electrical power may be
applied continuously during this period or at any instant up to
closure of the window as long as sufficient time is given to the
achieved the desired deformation of the seal before the window is
closed/latched. This approach may be preferred in some embodiments
because the window will remain sealed when stationary. In addition,
while the vehicle is not in operation, no power is required to
maintain the seal position, which could result in a drain of the
vehicle's battery. In some cases, an energy storage device such as
a capacitor could minimize battery drain and allow for operation
without battery drain.
[0033] As will be appreciated by those in the art, the blade can be
made to deform in a number of different manners. For example, in an
active seal structure having a prismatic shape, the blade could be
made to bend upon activation from an initially straight
configuration. Similarly the blade portion may be made to
straighten from a bent position. The function of this type of
deformation can vary depending on the type of operation
desired.
[0034] Several other approaches can be considered when using this
type of seal assembly. In this first case, activating the active
material activates the seal to increase the seal force. The seal
will then only be active when the power is applied to the seal. In
another approach, the sealed geometry is achieved when the power to
the active material component is withheld. The seal is then "pulled
back" when the power is applied to the active material component.
In this embodiment, the power is applied to the seal when the
window is moved. This approach is preferred in most cases because
the window will remain sealed in the power-off mode, i.e., when the
window is stationary.
[0035] FIG. 5 illustrates an active seal assembly 40 comprising a
seal body structure 44 and a portion 42 formed of the active
material, wherein activation of the active material can be employed
to selectively manipulate the shape and/or modulus properties of
the seal structure. By way of example, the seal assembly 40 may
comprise an electroactive gel or other active fluid disposed within
fluidly sealed tubing. Activating the active fluid can be used to
selectively alter the volume and/or flexural modulus properties of
the seal assembly. For example, a water filled bladder (not shown)
may be in fluid communication with the electroactive gel such that
upon activation of the gel with a suitable electrical signal the
gel volume increases by taking up water, i.e., swells, causing the
seal structure to selectively expand on demand.
[0036] Alternatively, a magnetorheological fluid may be disposed
within the seal body structure 44. Applying a magnetic signal can
selectively alter the rheological properties of the
magnetorheological fluid, thereby resulting in a change in the
flexural modulus properties of the seal.
[0037] Optional elements include an active valve in between the
seal and reservoir. In one embodiment, the active material based
fluid reservoir can, upon demand, forcibly transfer fluid into or
out of the seal structure. In this manner, the seal structure may
be either expanded (to force a more intimate seal with between
adjacent structural surfaces) or contracted (to reduce the sealing
force).
[0038] The active material based fluid reservoir can take many
forms. For example, it can be an explicit pump, e.g., a pump based
on shape memory alloys, piezoelectric ceramics, dielectric
elastomers, and the like. In such a design, fluid would move into
and out of the seal assembly upon demand using a compact fluid
pump. The reservoir can also be single-stroke in design. For
instance, the fluid reservoir could be a flexible structure
actuated using linear contractile elements of the active material
such as shape memory alloy wires, liquid crystal elastomers,
conductive polymers, electroactive polymer gels, and the like, or
expansion type elements such as dielectric elastomers,
piezoelectric polymers, and so forth. An improvement to linear type
devices may include an outer covering of the fluid reservoir
comprised of an active material. The advantages include, among
others, at least a factor of 2 to 3 increase in the displaced fluid
volume, given a fixed change in linear or aerial dimension of the
active material depending on the geometry chosen.
[0039] The combined structure of the active material and passive
elastic material is disposed suitably so as to forcibly increase or
decrease the volume available to be occupied by the fluid. The
biased fluid reservoir is fluidly connected with the seal structure
in such a way that fluid can transmit between the two structures;
the structure of the fluid reservoir is arranged such that, in the
absence of resistance, fluid is expelled from the reservoir. When
placed in communication, and upon activating the active material,
the seal would either allow fluid into the seal from the biased
fluid reservoir, or force fluid out of the seal and into the biased
fluid reservoir. This configuration preferably utilizes active
materials that are used in a one-way mode, or need to be "reset".
An active valve between the two components (seal body and fluid
reservoir) may also be a component of this embodiment.
[0040] FIG. 6 illustrates another example of an active seal
assembly 50, wherein an active material 52 such as a shape memory
alloy wire is embedded within a flexible seal structure 54.
Activation of the active material 36 selectively changes the shape
orientation and/or modulus properties of the seal structure 38. In
this manner, activation of the active material can alter the
sealing force applied against the window surface.
[0041] Alternatives include structuring the seal assembly with
stiffening elements that transmit force along the length of the
seal into displacement (and hence some degree of force enhancement
or reduction) in the sealing direction. The simplest design has a
"herringbone" structure as shown in FIGS. 7 and 8. Other suitable
designs will be apparent to those skilled in the art in view of
this disclosure. Force is applied at an end of the seal structure
and the herringbone (FIG. 7) is translated into vertical motion
(FIG. 8) of the seal, enabling enhanced sealing force.
[0042] An active material 62 can be employed to provide the
displacement change to the seal structure 64. A controller 66 is in
operative communication with the active material. The active
material can provide the force utilized to provide the displacement
or alternatively, may form the herringbone structure such that
activation of the active material changes its shape orientation to
effect the vertical displacement. Preferably, continuously
controllable active materials are employed in this embodiment,
e.g., dielectric elastomers, magnetic shape memory alloys, bimorph
piezoceramics or piezopolymers, IPMCs, and the like. Other designs
include deformation or buckling of the internal structure of the
seal.
[0043] In some embodiments, it may be desirable to have the overall
motion of the outer portion of the seal be in the sealing force
direction since shearing or motion at angles to this direction may
cause a gap in the seal at one end, or introduce a constraint on
the seal that involves shearing stresses perpendicular to the
sealing force direction which might slip during vehicle motion. As
such, it may be preferred to apply force at both ends of the seal
assembly. For example, the top surface and mid plane of the seal
assembly may preferably be made with a rigid internal structure
(such as a steel strip or a set of wires) that will constrain the
top surface of the seal at one end, and allow relative displacement
of the mid plane to propagate along the length of the seal.
[0044] In another embodiment as shown in FIGS. 9 and 10, an active
seal assembly 70 can be configured to have a twisting design. The
exemplary seal assembly exhibiting the twisting design in a power
off state (FIG. 9) and a powered state (FIG. 10). The active
material 72, e.g., wires formed of a shape memory alloy, would be
formed into a spoke like arrangement about a central axis within a
tubular seal structure 74. Upon activation, the spokes 72 would
change its shape orientation from the relative straight shape
orientation shown in FIG. 9 to the contracted shape orientation
shown in FIG. 10, thereby resulting in a contraction of the seal
assembly. Discontinuing the activation signal would cause the
original shape orientation to return. Of course, the active
material or geometry can be selected so as to provide expansion
upon activation, if desired.
[0045] Other approaches utilizing deformation of active components
to allow for improved sealing are approaches that use extensional
deformation of active materials. FIG. 11 illustrates a seal
assembly 80 shows how extensional dimension change could allow for
controllable sealing. An active material is intermediate one of the
stationary door surfaces 18 and/or 20 and an elastic seal structure
84. Activation of the active material 82 effects a change in length
dimension such that the seal force of the seal structure 84 against
the window 14 can be selectively varied. Once activated, the active
material will push the seal structure 84 against the window to
supply adequate pressure and contact area to form the seal.
[0046] Aside from strict shape recovery, any active material that
can be made to linearly expand or contract may be used to produce a
bending actuator by combining this material with a non-active
elastic member. In the literature, this is generally referred to as
a unimorph actuator. If both components are made of the same
material but made to deform in opposite directions, the material
becomes a bimorph actuator. For sealing applications, some
materials may be appropriate themselves for the outer surface of
the seal, while others require a compliant coating material to
improve the sealing surface. In this case, the basic unimorph or
bimorph actuator can be augmented with a coating of a highly
compliant material that will help to form an effective seal when
the seal material is activated.
[0047] For actuation mechanisms, using a material that expands or
contracts can induce bending to the left or right, respectively. In
the bimorph actuator, either direction can also be achieved
depending on orientation of the active layers. A unimorph actuator
may be created by using a shape memory alloy, conducting polymer,
electrostrictive polymer, or other axially straining material,
along with an elastic component that causes bending couple to be
created. The elastic member can belong to many material classes
including metallic alloys, polymers, and ceramics. Preferred
materials are those which exhibit large elastic strain limits, and
those which can efficiently store mechanical energy. Secondary
considerations include those which may be easily bonded to the
active material, have properties that are acceptable in the working
temperature range, and have adequate toughness to survive repeated
actuation. A bimorph actuator may be created for any material in
which the material may be driven into both extension and
compression depending on the driving signal. For example,
piezoelectric materials can be used for this effect. In addition,
ionic polymer actuators such as IPMC and conducting polymers
intrinsically exhibit this effect due to the transport of ionic
species that cause swelling across a membrane.
[0048] As is apparent from the discussion above, the active seal
assemblies that interface with the movable automotive window can be
configured in a variety of forms and shape as well as be configured
with a variety of active materials or combination thereof. The
particular shape and forms are not intended to be limited. Other
shapes and forms contemplated include, but are not intended to be
limited to, a channel having one or more vanes, and the like.
Likewise, the various forms and shapes can comprise, in whole or in
part, various active materials.
[0049] As previously discussed, suitable active materials include
piezoelectric materials, shape memory alloys, shape memory
polymers, ferromagnetic shape memory alloys, an electroactive
polymers, electrorheological fluids, a magnetorheological
elastomers, dielectric elastomers, magnetorheological fluids, ionic
polymer metal composites, or combinations comprising at least one
of the foregoing materials.
[0050] Suitable piezoelectric materials include, but are not
intended to be limited to, inorganic compounds, organic compounds,
and metals. With regard to organic materials, all of the polymeric
materials with non-centrosymmetric structure and large dipole
moment group(s) on the main chain or on the side-chain, or on both
chains within the molecules, can be used as suitable candidates for
the piezoelectric film. Exemplary polymers include, for example,
but are not limited to, poly(sodium 4-styrenesulfonate), poly
(poly(vinylamine)backbone azo chromophore), and their derivatives;
polyfluorocarbons, including polyvinylidenefluoride, its co-polymer
vinylidene fluoride ("VDF"), co-trifluoroethylene, and their
derivatives; polychlorocarbons, including poly(vinyl chloride),
polyvinylidene chloride, and their derivatives; polyacrylonitriles,
and their derivatives; polycarboxylic acids, including
poly(methacrylic acid), and their derivatives; polyureas, and their
derivatives; polyurethanes, and their derivatives; bio-molecules
such as poly-L-lactic acids and their derivatives, and cell
membrane proteins, as well as phosphate bio-molecules such as
phosphodilipids; polyanilines and their derivatives, and all of the
derivatives of tetramines; polyamides including aromatic polyamides
and polyimides, including Kapton and polyetherimide, and their
derivatives; all of the membrane polymers; poly(N-vinyl
pyrrolidone) (PVP) homopolymer, and its derivatives, and random
PVP-co-vinyl acetate copolymers; and all of the aromatic polymers
with dipole moment groups in the main-chain or side-chains, or in
both the main-chain and the side-chains, and mixtures thereof.
[0051] Piezoelectric material can also comprise metals selected
from the group consisting of lead, antimony, manganese, tantalum,
zirconium, niobium, lanthanum, platinum, palladium, nickel,
tungsten, aluminum, strontium, titanium, barium, calcium, chromium,
silver, iron, silicon, copper, alloys comprising at least one of
the foregoing metals, and oxides comprising at least one of the
foregoing metals. Suitable metal oxides include SiO.sub.2,
Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2, SrTiO.sub.3, PbTiO.sub.3,
BaTiO.sub.3, FeO.sub.3, Fe.sub.3O.sub.4, ZnO, and mixtures thereof
and Group VIA and IIB compounds, such as CdSe, CdS, GaAs,
AgCaSe.sub.2, ZnSe, GaP, InP, ZnS, and mixtures thereof.
Preferably, the piezoelectric material is selected from the group
consisting of polyvinylidene fluoride, lead zirconate titanate, and
barium titanate, and mixtures thereof.
[0052] Shape memory polymers (SMPs) generally refer to a group of
polymeric materials that demonstrate the ability to return to some
previously defined shape when subjected to an appropriate thermal
stimulus. The shape memory polymer may be in the form of a solid or
a foam as may be desired for some embodiments. Shape memory
polymers are capable of undergoing phase transitions in which their
shape orientation is altered as a function of temperature.
Generally, SMPs are co-polymers comprised of at least two different
units which may be described as defining different segments within
the copolymer, each segment contributing differently to the
flexural modulus properties and thermal transition temperatures of
the material. The term "segment" refers to a block, graft, or
sequence of the same or similar monomer or oligomer units that are
copolymerized with a different segment to form a continuous
crosslinked interpenetrating network of these segments. These
segments may be combination of crystalline or amorphous materials
and therefore may be generally classified as a hard segment(s) or a
soft segment(s), wherein the hard segment generally has a higher
glass transition temperature (Tg) or melting point than the soft
segment. Each segment then contributes to the overall flexural
modulus properties of the SMP and the thermal transitions thereof.
When multiple segments are used, multiple thermal transition
temperatures may be observed, wherein the thermal transition
temperatures of the copolymer may be approximated as weighted
averages of the thermal transition temperatures of its comprising
segments. With regard to shape memory polymer foams, the structure
may be open celled or close celled as desired.
[0053] In practice, the SMPs are alternated between one of at least
two shape orientations such that at least one orientation will
provide a size reduction relative to the other orientation(s) when
an appropriate thermal signal is provided. To set a permanent
shape, the shape memory polymer must be at about or above its
melting point or highest transition temperature (also termed "last"
transition temperature). SMP foams are shaped at this temperature
by blow molding or shaped with an applied force followed by cooling
to set the permanent shape. The temperature necessary to set the
permanent shape is generally between about 40.degree. C. to about
200.degree. C. After expansion by fluid, the permanent shape is
regained when the applied force is removed, and the expanded SMP is
again brought to or above the highest or last transition
temperature of the SMP. The Tg of the SMP can be chosen for a
particular application by modifying the structure and composition
of the polymer.
[0054] The temperature needed for permanent shape recovery can
generally be set at any temperature between about -63.degree. C.
and about 160.degree. C. or above. Engineering the composition and
structure of the polymer itself can allow for the choice of a
particular temperature for a desired application. A preferred
temperature for shape recovery is greater than or equal to about
-30.degree. C., more preferably greater than or equal to about
20.degree. C., and most preferably a temperature greater than or
equal to about 70.degree. C. Also, a preferred temperature for
shape recovery is less than or equal to about 250.degree. C., more
preferably less than or equal to about 200.degree. C., and most
preferably less than or equal to about 180.degree. C.
[0055] Suitable shape memory polymers can be thermoplastics,
interpenetrating networks, semi-interpenetrating networks, or mixed
networks. The polymers can be a single polymer or a blend of
polymers. The polymers can be linear or branched thermoplastic
elastomers with side chains or dendritic structural elements.
Suitable polymer components to form a shape memory polymer include,
but are not limited to, polyphosphazenes, poly(vinyl alcohols),
polyamides, polyester amides, poly(amino acid)s, polyanhydrides,
polycarbonates, polyacrylates, polyalkylenes, polyacrylamides,
polyalkylene glycols, polyalkylene oxides, polyalkylene
terephthalates, polyortho esters, polyvinyl ethers, polyvinyl
esters, polyvinyl halides, polyesters, polylactides,
polyglycolides, polysiloxanes, polyurethanes, polyethers, polyether
amides, polyether esters, and copolymers thereof. Examples of
suitable polyacrylates include poly(methyl methaciylate),
poly(ethyl methacrylate), poly(butyl methacrylate), poly(isobutyl
methacrylate), poly(hexyl methacrylate), poly(isodecyl
methacrylate), poly(lauryl mnethacrylate), poly(phenyl
methacrylate), poly(methyl acrylate), poly(isopropyl acrylate),
poly(isobutyl acrylate) and poly(octadecylacrylate). Examples of
other suitable polymers include polystyrene, polypropylene,
polyvinyl phenol, polyvinylpyrrolidone, chlorinated polybutylene,
poly(octadecyl vinyl ether), ethylene vinyl acetate, polyethylene,
poly(ethylene oxide)-poly(ethylene terephthalate),
polyethylene/nylon (graft copolymer), polycaprolactones-polyamide
(block copolymer), poly(caprolactone) diniethacrylate-n-butyl
acrylate, poly(norbornyl-polyhedral oligomeric silsequioxane),
polyvinylchloride, urethane/butadiene copolymers, polyurethane
block copolymers, styrene-butadienestyrene block copolymers, and
the like.
[0056] Conducting polymerization of different monomer segments with
a blowing agent can be used to form the shape memory polymer foam.
The blowing agent can be of the decomposition type (evolves a gas
upon chemical decomposition) or an evaporation type (which
vaporizes without chemical reaction). Exemplary blowing agents of
the decomposition type include, but are not intended to be limited
to, sodium bicarbonate, azide compounds, ammonium carbonate,
ammonium nitrite, light metals which evolve hydrogen upon reaction
with water, azodicarbonamide,
N,N'-dinitrosopentamethylenetetramine, and the like. Exemplary
blowing agents of the evaporation type include, but are not
intended to be limited to, trichloromonofluoromethane,
trichlorotrifluoroethane, methylene chloride, compressed nitrogen
gas, and the like. The material can then be reverted to the
permanent shape by heating the material above its Tg but below the
highest thermal transition temperature or melting point. Thus, by
combining multiple soft segments it is possible to demonstrate
multiple temporary shapes and with multiple hard segments it may be
possible to demonstrate multiple permanent shapes.
[0057] Similar to shape memory polymers, shape memory alloys exist
in several different temperature-dependent phases. The most
commonly utilized of these phases are the so-called martensite and
austenite phases. In the following discussion, the martensite phase
generally refers to the more deformable, lower temperature phase
whereas the austenite phase generally refers to the more rigid,
higher temperature phase. When the shape memory alloy is in the
martensite phase and is heated, it begins to change into the
austenite phase. The temperature at which this phenomenon starts is
often referred to as austenite start temperature (As). The
temperature at which this phenomenon is complete is called the
austenite finish temperature (Af). When the shape memory alloy is
in the austenite phase and is cooled, it begins to change into the
martensite phase, and the temperature at which this phenomenon
starts is referred to as the martensite start temperature (Ms). The
temperature at which austenite finishes transforming to martensite
is called the martensite finish temperature (Mf). Generally, the
shape memory alloys are softer and more easily deformable in their
martensitic phase and are harder, stiffer, and/or more rigid in the
austenitic phase. In view of the foregoing properties, expansion of
the shape memory alloy is preferably at or below the austenite
transition temperature (at or below As). Subsequent heating above
the austenite transition temperature causes the expanded shape
memory foam to revert back to its permanent shape. Thus, a suitable
activation signal for use with shape memory alloys is a thermal
activation signal having a magnitude to cause transformations
between the martensite and austenite phases.
[0058] The temperature at which the shape memory alloy remembers
its high temperature form when heated can be adjusted by slight
changes in the composition of the alloy and through heat treatment.
In nickel-titanium shape memory alloys, for instance, it can be
changed from above about 100.degree. C. to below about -100.degree.
C. The shape recovery process occurs over a range of just a few
degrees and the start or finish of the transformation can be
controlled to within a degree or two depending on the desired
application and alloy composition. The mechanical properties of the
shape memory alloy vary greatly over the temperature range spanning
their transformation, typically providing shape memory effects,
superelastic effects, and high damping capacity.
[0059] Suitable shape memory alloy materials for fabricating the
foams include, but are not intended to be limited to,
nickel-titanium based alloys, indium-titanium based alloys,
nickel-aluminum based alloys, nickel-gallium based alloys, copper
based alloys (e.g., copper--zinc alloys, copper-aluminum alloys,
copper-gold, and copper-tin alloys), gold-cadmium based alloys,
silver-cadmium based alloys, indium-cadmium based alloys,
manganese-copper based alloys, iron-platinum based alloys,
iron-palladium based alloys, and the like. The alloys can be
binary, ternary, or any higher order so long as the alloy
composition exhibits a shape memory effect, e.g., change in shape
orientation, changes in yield strength, and/or flexural modulus
properties, damping capacity, superelasticity, and the like. A
preferred shape memory alloy is a nickel-titanium based alloy
commercially available under the trademark FLEXINOL from Dynalloy,
Inc. Selection of a suitable shape memory alloy composition depends
on the temperature range where the component will operate.
[0060] Suitable magnetorheological fluid materials include, but are
not intended to be limited to, ferromagnetic or paramagnetic
particles dispersed in a carrier fluid. Suitable particles include
iron; iron alloys, such as those including aluminum, silicon,
cobalt, nickel, vanadium, molybdenum, chromium, tungsten, manganese
and/or copper; iron oxides, including Fe.sub.2O.sub.3 and
Fe.sub.3O.sub.4; iron nitride; iron carbide; carbonyl iron; nickel
and alloys of nickel; cobalt and alloys of cobalt; chromium
dioxide; stainless steel; silicon steel; and the like. Examples of
suitable particles include straight iron powders, reduced iron
powders, iron oxide powder/straight iron powder mixtures and iron
oxide powder/reduced iron powder mixtures. A preferred
magnetic-responsive particulate is carbonyl iron, more preferably,
reduced carbonyl iron.
[0061] The particle size should be selected so that the particles
exhibit multi-domain characteristics when subjected to a magnetic
field. Diameter sizes for the particles can be less than or equal
to about 1,000 micrometers, with less than or equal to about 500
micrometers preferred, and less than or equal to about 100
micrometers more preferred. Also preferred is a particle diameter
of greater than or equal to about 0.1 micrometer, with greater than
or equal to about 0.5 more preferred, and greater than or equal to
about 10 micrometers especially preferred. The particles are
preferably present in an amount between about 5.0 to about 50
percent by volume of the total MR fluid composition.
[0062] Suitable carrier fluids include organic liquids, especially
non-polar organic liquids. Examples include, but are not limited
to, silicone oils; mineral oils; paraffin oils; silicone
copolymers; white oils; hydraulic oils; transformer oils;
halogenated organic liquids, such as chlorinated hydrocarbons,
halogenated paraffins, perfluorinated polyethers and fluorinated
hydrocarbons; diesters; polyoxyalkylenes; fluorinated silicones;
cyanoalkyl siloxanes; glycols; synthetic hydrocarbon oils,
including both unsaturated and saturated; and combinations
comprising at least one of the foregoing fluids.
[0063] The viscosity of the carrier component can be less than or
equal to about 100,000 centipoise, with less than or equal to about
10,000 centipoise preferred, and less than or equal to about 1,000
centipoise more preferred. Also preferred is a viscosity of greater
than or equal to about 1 centipoise, with greater than or equal to
about 250 centipoise preferred, and greater than or equal to about
500 centipoise especially preferred.
[0064] Aqueous carrier fluids may also be used, especially those
comprising hydrophilic mineral clays such as bentonite or
hectorite. The aqueous carrier fluid may comprise water or water
comprising a small amount of polar, water-miscible organic solvents
such as methanol, ethanol, propanol, dimethyl sulfoxide, dimethyl
formamide, ethylene carbonate, propylene carbonate, acetone,
tetrahydrofuran, diethyl ether, ethylene glycol, propylene glycol,
and the like. The amount of polar organic solvents is less than or
equal to about 5.0% by volume of the total MR fluid, and preferably
less than or equal to about 3.0%. Also, the amount of polar organic
solvents is preferably greater than or equal to about 0.1%, and
more preferably greater than or equal to about 1.0% by volume of
the total MR fluid. The pH of the aqueous carrier fluid is
preferably less than or equal to about 13, and preferably less than
or equal to about 9.0. Also, the pH of the aqueous carrier fluid is
greater than or equal to about 5.0, and preferably greater than or
equal to about 8.0.
[0065] Natural or synthetic bentonite or hectorite may be used. The
amount of bentonite or hectorite in the MR fluid is less than or
equal to about 10 percent by weight of the total MR fluid,
preferably less than or equal to about 8.0 percent by weight, and
more preferably less than or equal to about 6.0 percent by weight.
Preferably, the bentonite or hectorite is present in greater than
or equal to about 0.1 percent by weight, more preferably greater
than or equal to about 1.0 percent by weight, and especially
preferred greater than or equal to about 2.0 percent by weight of
the total MR fluid.
[0066] Optional components in the MR fluid include clays,
organoclays, carboxylate soaps, dispersants, corrosion inhibitors,
lubricants, extreme pressure anti-wear additives, antioxidants,
thixotropic agents and conventional suspension agents. Carboxylate
soaps include ferrous oleate, ferrous naphthenate, ferrous
stearate, aluminum di- and tri-stearate, lithium stearate, calcium
stearate, zinc stearate and sodium stearate, and surfactants such
as sulfonates, phosphate esters, stearic acid, glycerol monooleate,
sorbitan sesquioleate, laurates, fatty acids, fatty alcohols,
fluoroaliphatic polymeric esters, and titanate, aluminate and
zirconate coupling agents and the like. Polyalkylene diols, such as
polyethylene glycol, and partially esterified polyols can also be
included.
[0067] Suitable MR elastomer materials include, but are not
intended to be limited to, an elastic polymer matrix comprising a
suspension of ferromagnetic or paramagnetic particles, wherein the
particles are described above. Suitable polymer matrices include,
but are not limited to, poly-alpha-olefins, natural rubber,
silicone, polybutadiene, polyethylene, polyisoprene, and the
like.
[0068] Electroactive polymers include those polymeric materials
that exhibit piezoelectric, pyroelectric, or electrostrictive
properties in response to electrical or mechanical fields. An
example of an electrostrictive-grafted elastomer with a
piezoelectric poly(vinylidene fluoride-trifluoro-ethylene)
copolymer. This combination has the ability to produce a varied
amount of ferroelectric-electrostrictive molecular composite
systems. These may be operated as a piezoelectric sensor or even an
electrostrictive actuator.
[0069] Materials suitable for use as an electroactive polymer may
include any substantially insulating polymer or rubber (or
combination thereof) that deforms in response to an electrostatic
force or whose deformation results in a change in electric field.
Exemplary materials suitable for use as a pre-strained polymer
include silicone elastomers, acrylic elastomers, polyurethanes,
thermoplastic elastomers, copolymers comprising PVDF,
pressure-sensitive adhesives, fluoroelastomers, polymers comprising
silicone and acrylic moieties, and the like. Polymers comprising
silicone and acrylic moieties may include copolymers comprising
silicone and acrylic moieties, polymer blends comprising a silicone
elastomer and an acrylic elastomer, for example.
[0070] Materials used as an electroactive polymer may be selected
based on one or more material properties such as a high electrical
breakdown strength, a low modulus of elasticity--(for large or
small deformations), a high dielectric constant, and the like. In
one embodiment, the polymer is selected such that is has an elastic
modulus at most about 100 MPa. In another embodiment, the polymer
is selected such that is has a maximum actuation pressure between
about 0.05 MPa and about 10 MPa, and preferably between about 0.3
MPa and about 3 MPa. In another embodiment, the polymer is selected
such that is has a dielectric constant between about 2 and about
20, and preferably between about 2.5 and about 12. The present
disclosure is not intended to be limited to these ranges. Ideally,
materials with a higher dielectric constant than the ranges given
above would be desirable if the materials had both a high
dielectric constant and a high dielectric strength. In many cases,
electroactive polymers may be fabricated and implemented as thin
films. Thicknesses suitable for these thin films may be below 50
micrometers.
[0071] As electroactive polymers may deflect at high strains,
electrodes attached to the polymers should also deflect without
compromising mechanical or electrical performance. Generally,
electrodes suitable for use may be of any shape and material
provided that they are able to supply a suitable voltage to, or
receive a suitable voltage from, an electroactive polymer. The
voltage may be either constant or varying over time. In one
embodiment, the electrodes adhere to a surface of the polymer.
Electrodes adhering to the polymer are preferably compliant and
conform to the changing shape of the polymer. Correspondingly, the
present disclosure may include compliant electrodes that conform to
the shape of an electroactive polymer to which they are attached.
The electrodes may be only applied to a portion of an electroactive
polymer and define an active area according to their geometry.
Various types of electrodes suitable for use with the present
disclosure include structured electrodes comprising metal traces
and charge distribution layers, textured electrodes comprising
varying out of plane dimensions, conductive greases such as carbon
greases or silver greases, colloidal suspensions, high aspect ratio
conductive materials such as carbon fibrils and carbon nanotubes,
and mixtures of ionically conductive materials.
[0072] Materials used for electrodes of the present disclosure may
vary. Suitable materials used in an electrode may include graphite,
carbon black, colloidal suspensions, thin metals including silver
and gold, silver filled and carbon filled gels and polymers, and
ionically or electronically conductive polymers. It is understood
that certain electrode materials may work well with particular
polymers and may not work as well for others. By way of example,
carbon fibrils work well with acrylic elastomer polymers while not
as well with silicone polymers.
[0073] While the disclosure has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the disclosure. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
disclosure without departing from the essential scope thereof.
Therefore, it is intended that the disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this disclosure, but that the disclosure will include
all embodiments falling within the scope of the appended
claims.
* * * * *