WO2006093479A1

WO2006093479A1 - System and method of reducing vibration in a tire

Info

Publication number: WO2006093479A1
Application number: PCT/US2005/005831
Authority: WO
Inventors: George P. O'brien; Jack Thiesen
Original assignee: Societe De Technologie Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2005-02-24
Filing date: 2005-02-24
Publication date: 2006-09-08
Also published as: EP1851074A4; TW200637741A; CN101084126A; JP2008531373A; EP1851074A1

Abstract

A tire assembly with integrated features for adjusting the resonance characteristics of a tire structure includes a pneumatic tire structure, a dielectric elastomer actuator configuration and a charge source. The dielectric elastomer actuator configuration is integrated with selected interior surface locations of the tire structure and may correspond to such embodiments as a plurality of dielectric elastomer portions attached between two rubber plates, a plurality of dielectric elastomer sheets combined to define a volumetric cavity, or a plurality of dielectric elastomer cords attached between interior sidewall locations of a tire structure. Each dielectric elastomer portion includes a layer of elastomeric material provided with first and second electrodes on opposing surfaces thereof and may correspond to a single sheet, a folded sheet, a pleated sheet or a rolled sheet. The charge source is coupled to selected of the first and second electrodes of the dielectric elastomer portions and is configured to selectively apply voltage thereto. The charge source dually functions in some embodiments as an energy storage device for storing electric charge generated when the dielectric elastomer portions are subjected to mechanical forces.

Description

PATENT

Attorney Docket No.: MIC-39-PCT Michelin Reference No.: P50-0164 UNITED STATES PATENT APPLICATION

TITLE: SYSTEM AND METHOD OF REDUCING VIBRATION IN A TIRE

FIELD OF THE INVENTION

[0001] The present invention generally concerns a system and method for reducing vibration in a tire or corresponding wheel assembly. More particularly, exemplary technology is provided for disrupting the cavity resonance of a tire, adjusting sidewall stiffness of a tire, and controlling tire performance by affecting the size of a tire's contact patch.

BACKGROUND OF THE INVENTION

[0002] The occurrence of wheel vibration is an inherent issue that affects the durability, performance and comfort levels associated with many types of mechanized transportation. As a vehicle travels along a ground surface, impulse and frictional energy from the ground surface may be transferred into vibrational modes of energy within its tires and/or wheel assemblies. Such generated vibrations tend to increase a tire's temperature and also generate noise that may cause discomfort to a driver. Thus, it may be desirable to limit the amount of mechanical vibration associated with a vehicle's tire assemblies.

[0003] As with all physical systems subjected to a driving force, a rotating tire acts as a cavity resonator. Thus, a portion of a tire's mechanical energy will be converted into resonance vibrations at particular vehicle speeds. This phenomenon may be of particular concern for tire assemblies since resonance vibrations can often propagate with less attenuation than energy in other vibrational modes. By changing the resonance modes of a mechanical system, resonant energy levels can be attenuated and physical vibrations can be lessened.

[0004] Select embodiments of the present subject matter provide for actuator mechanisms that utilize dielectric elastomers to help control the vibrational characteristics and resonant properties of a tire or wheel assembly. Certain advantages of dielectric elastomers have been previously recognized, as disclosed in U.S. Patent No. 6,545,384 (Pelrine et al.), and in U.S. Patent Application Publication No. US 2002/0130673 (Pelrine et al.), which are incorporated herein by reference for all purposes. However, this technology is constantly improving, thus paving the way for new applications in which dielectric elastomers may be employed. Aspects of the present subject matter address the presently disclosed concerns and others related to the occurrence of vibrational energy in tire and wheel assemblies and offer improved methods for reducing such vibration. Such methods and others utilize dielelectric elastomer configurations integrated with a tire or wheel assembly, as will be described in detail in the remainder of this application.

SUMMARY OF THE INVENTION

[0005] In view of the recognized features addressed by the present subject matter, improved features and methodology for reducing vibration in a tire has been developed. Dielectric elastomer materials are employed as actuator devices to adjust the cavity resonance characteristics of a tire. Such a dielectric elastomer corresponds to a portion of elastomer material with first and second electrodes fashioned on opposing sides of the elastomer. Application of a controlled voltage to the electrodes will yield a proportional amount of deformation, and thus mechanical actuation, within the dielectric elastomer.

[0006] Various features and aspects of the subject dielectric elastomer technology and corresponding tire applications offer a plurality of advantages. The disclosed dielectric elastomer materials are provided with significant design versatility due to their unique electrode configurations. The elastomer material can be formed in sheets, folded sheets, rolled cords, or other configurations and customized for integration in a variety of particular mounting environments.

[0007] Another advantage of the present technology is that the disclosed dielectric elastomer material can be utilized to disrupt the cavity resonance of a tire, thus reducing tire vibrations. Reduction of tire vibrations can reduce the temperature within a tire and the noise generated by a tire assembly. Reduced vibrations can also prolong the life of a tire and increase levels of relative driver comfort.

[0008] A still further advantage of the present subject matter is that the disclosed dielectric elastomer actuators can be used to affect sidewall stiffness, and thus certain performance characteristics, of a tire. Control of sidewall deflection provides the ability to increase a tire's contact patch to improve traction or to decrease a tire's contact patch to reduce rolling resistance and improve overall fuel efficiency.

[0009] In one exemplary embodiment of the present subject matter, a tire assembly with integrated features for adjusting the cavity resonance of a tire includes a pneumatic tire structure, a dielectric elastomer actuator configuration and a charge source. The pneumatic tire structure is characterized by a crown having an exterior tread portion for making contact with a ground surface, bead portions for seating the tire to a wheel rim, sidewall portions extending between each bead portion and the crown, and interior crown and sidewall surfaces. The dielectric elastomer actuator configuration is integrated at selected locations along the interior crown and sidewall surfaces of the tire structure and includes at least one dielectric elastomer portion. The dielectric elastomer portion includes a layer of elastomeric material provided with first and second opposing electrodes on opposing surfaces thereof. The charge source is coupled to selected of the first and second opposing electrodes of the dielectric elastomer actuator configuration for selectively applying voltage to the at least one dielectric elastomer portion and thus being capable of adjusting the effective surface area of the at least one dielectric elastomer portion.

[0010] In some more particular tire assembly embodiments, the dielectric elastomer actuator configuration includes two rubber plates that may provide an open or completely encased enclosure for a plurality of dielectric elastomer portions attached between the rubber plates. In such a configuration, the width between rubber plates can be adjusted by selective application of voltage levels to the dielectric elastomer portions. Yet another dielectric elastomer actuator configuration corresponds to one or more integrated dielectric elastomer sheets formed to define a volumetric region having a variable volume dependent on the level of electric charge applied to the one or more dielectric elastomer sheets. A still further dielectric elastomer actuator configuration corresponds to a plurality of dielectric elastomer cords attached between selected opposing interior sidewall surfaces of a tire structure. Dielectric elastomer portions may correspond in some embodiments to single sheets, folded sheets, pleated sheets or to rolled cords.

[0011] In still further more particular embodiments of the present subject matter, a microcontroller may be coupled to the charge source and configured to monitor and regulate the amount of voltage applied from the charge source to the at least one dielectric elastomer portion. A condition-responsive device (e.g., sensor, etc.) may also be coupled to the microcontroller and configured to sense a predetermined characteristic associated with the tire structure (e.g., temperature, pressure, vibrational or noise levels, etc.). Monitored levels of such characteristics help regulate the variable amount of voltage to be applied from the charge source to the at least one dielectric elastomer portion. A vehicle operator may also provide input via a user input interface to manually control the levels of applied voltage to effect certain desired levels of vehicle performance.

[0012] Another embodiment of the present subject matter corresponds to a method of adjusting the cavity resonance of a tire and includes such steps as providing at least one dielectric elastomer portion along selected interior surfaces of a tire structure, monitoring at least one predetermined characteristic associated with the tire structure (e.g., temperature, pressure, vibration, noise), and selectively applying electric charge to the at least one dielectric elastomer portion. The amount of electric charge applied is dependent on the monitored levels of the at least one predetermined characteristic and the amount of charge applied determines an amount of mechanical deflection of the at least one dielectric elastomer portion resulting in adjustment of the resonance characteristics of the tire structure. The step of providing at least one dielectric elastomer portion may more particularly correspond to providing such exemplary dielectric elastomer actuator configurations as previously mentioned above.

[0013] A still further embodiment of the present subject matter corresponds to a tire assembly with integrated features for adjusting tire sidewall stiffness and for harvesting electrical energy. Such a tire assembly may include a pneumtic tire structure as previously described, a plurality of dielectric elastomer portions and at least one energy storage device. The plurality of dielectric elastomer portions are attached between selected interior surfaces of the pneumatic tire structure and each includes a layer of elastomeric material provided with first and second electrodes on opposing surfaces thereof. Such portions may be rolled to form dielectric elastomer cords in one embodiment. The dielectric elastomer portions are adapted to generate electrical energy upon the application of mechanical forces and to experience mechanical deformation upon the application of electrical energy. The at least one energy storage device coupled to the plurality of dielectric elastomer portions is configured to store selected amounts of electrical energy generated by the dielectric elastomer portions and to act as a charge source from which voltage may be applied when variable levels of mechanical deformation are desired.

[0014] Additional objects and advantages of the present subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features and steps hereof may be practiced in various embodiments and uses of the invention without departing from the spirit and scope of the subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like.

[0015] Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of the present subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures). Additional embodiments of the present subject matter, not necessarily expressed in this summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objectives above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0017] Figure 1 provides a generally cross-sectional perspective view of an exemplary pneumatic tire structure and dielectric elastomer actuator configuration, namely a configuration with dielectric elastomer portions provided between two rubber plates, in accordance with a first embodiment of the present invention;

[0018] Figure 2 A provides a perspective view of the dielectric elastomer actuator configuration of Figure 1;

[0019] Figure 2B provides a plan representation of an exemplary dielectric elastomer cord from the dielectric elastomer actuator configurations of Figures 1 and 2A depicting cord positions with and without charge applied thereto;

[0020] Figures 3A through 3D respectively illustrate various different configurations of a dielectric elastomer portion in accordance with the presently disclosed technology, namely single sheet, folded sheet, pleated sheet, and rolled sheet configurations;

[0021] Figure 4 provides a generally cross-sectional perspective view of an exemplary pneumatic tire structure and dielectric elastomer actuator configuration, namely a variable volume cavity formed of dielectric elastomer portions, in accordance with a second embodiment of the present invention;

[0022] Figure 5 provides a perspective representation of the exemplary variable volume cavity of Figure 4 depicting exemplary positions of the dielectric elastomer portions with and without charge applied thereto;

[0023] Figure 6 provides a generally cross-sectional perspective view of an exemplary pneumatic tire structure and dielectric elastomer actuator configuration, namely a plurality of dielectric elastomer portions configured to adjust the sidewall stiffness of a tire structure as well as harvest electrical energy therefrom, in accordance with a third embodiment of the present invention; and

[0024] Figure 7 provides a block diagram representation of exemplary electronics components for interfacing with a dielectric elastomer actuator in accordance with select embodiments of the present invention. [0025] Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] As discussed in the Brief Summary of the Invention section, the present subject matter is particularly concerned with features and steps for adjusting the cavity resonance of a pneumatic tire structure. Figures 1 , 2A and 2B respectively illustrate aspects of a first tire assembly embodiment with a pneumatic tire structure and an incorporated dielectric elastomer actuator configuration for adjusting tire resonance properties. The first embodiment includes a plurality of dielectric elastomer portions provided between two parallel rubber plates. Aspects of a second exemplary tire assembly are depicted in Figures 4 and 5 and include a variable volume cavity made of integrated portions of dielectric elastomer sheets suitable for incorporation with an inner surface of a pneumatic tire structure. Figure 6 illustrates a still further embodiment of a dielectric elastomer actuator configuration integrated with a pneumatic tire structure. The embodiment of Figure 6 includes a plurality of dielectric elastomer portions attached at various inner sidewall locations of a tire. Such a configuration of dielectric elastomer portions can be utilized to adjust the sidewall stiffness and corresponding contact patch size of a tire as well as to harvest electrical energy created by mechanical deformation of the dielectric elastomer portions. Various exemplary configurations for the dielectric elastomer portions, including sheets, folded sheets, pleated sheets and rolled cords, are illustrated in Figures 3A through 3D respectively. Exemplary circuitry components for interfacing with the dielectric elastomer actuators of the present technology are discussed with reference to Figure 7.

[0027] Referring now to Figure 1, a first exemplary tire assembly 10 in accordance with the present subject matter is illustrated. Tire assembly 10 is configured with features for adjusting the cavity resonance of a pneumatic tire structure 12 by an integrated dielectric elastomer actuator configuration 14. Tire structure 12 is typically characterized by a crown 16 which supports an exterior tread portion 18 and sidewalls 20 that extend to bead portions 22. Tire beads 22 are generally provided such that the tire structure 12 can be effectively seated to the rim of a wheel assembly. An inner liner of air-impermeable material forms the interior surface of the tire, including interior crown surface 24 and interior sidewall surfaces 26. A carcass extends between beads 22 across sidewall portions 20 and crown 16, and under inflation pressure defines the tire's shape and transmits forces for traction and steering. Belt package 21 is provided within tire structure 12 generally along the crown 16.

[0028] When tire structure 12 is mounted on a wheel rim and subjected to driving forces associated with vehicle rotation along a ground surface, the rotating tire structure 12 acts as a cavity resonator. Thus, a portion of the tire's mechanical energy will be converted into resonance vibrations at particular vehicle speeds. This phenomenon may be of particular concern for tire assemblies since resonance vibrations can often propagate with less attenuation than energy in other vibrational modes. The dielectric elastomer actuator configuration 14 is thus incorporated with pneumatic tire structure 12 to adjust the resonance modes of the mechanical system. As such, resonant energy levels can be attenuated and physical vibrations can be lessened by selective actuation of the dielectric elastomer configuration 14.

[0029] A more detailed view of dielectric elastomer actuator configuration 14 is provided in Figure 2A. Exemplary actuator configuration 14 includes a plurality of dielectric elastomer portions 30 provided between a generally parallel pair of rubber plates 32. The disruption of cavity resonance of a tire structure 12 with which the actuator configuration is incorporated is made possible by adjusting the width 34 between rubber plates 32. Width 34 is adjusted by selective application of a charge source (voltage level) to the dielectric elastomer portions 30. Figure 2B depicts one such dielectric elastomer portion 30 in different positional states. The dielectric elastomer portion provided in position 30a (represented by solid lines) is exemplary of such portion without charge applied and the same portion provided in position 30b (represented by dashed lines) is exemplary of such portion with a predetermined amount of charge applied thereto.

[0030] Dielectric elastomer portions 30 may correspond to a variety of different configurations, some of which are illustrated in Figures 3 A through 3D, respectively. Each of the various forms of dielectric elastomer portions 30 as illustrated herein generally comprise a relatively thin layer of insulating (dielectric) elastomeric polymer material 36 provided between two electrode layers 38 formed on opposing surfaces of the elastomeric layer 36. The electrode layers 38 are preferably formed of a relatively stretchable (compliant) material, such as graphite, carbon black or other appropriate material that is applied to the elastomeric layer by spraying, screen printing, photolithography or the like. It should be appreciated that the opposing electrode layers 38 may correspond in some embodiments to a plurality of distinct electrode portions as opposed to single continuous electrode layers. Dielectric elastomer portion 30 may correspond to a single sheet configuration as depicted in Figure 3A, a folded sheet configuration as illustrated in Figure 3B, a pleated sheet configuration as in the exploded view of Figure 3 C or a sheet rolled into a cord configuration as represented in Figure 3D. In the exemplary embodiments of Figures 3B through 3D, more surface area of the dielectric elastomer material is provided in a smaller volume, thus yielding a greater potential for mechanical deformation of the material than with the single sheet configuration of Figure 3 A. It should be appreciated that although many different exemplary configurations for dielectric elastomer portions 30 are discussed and illustrated herein, additional configurations are also possible. As such, the scope of the present subject matter should not be limited to the specific configurations presented herein.

[0031] The principles of operation of the dielectric elastomer actuators are based on properties of the elastomeric material 36 that cause it to deform due to Maxwell's forces between the electrodes 38. When a voltage difference is applied to the dielectric elastomer actuator, positive charges appear on one electrode while negative charges appear on the other. These charges attract each other causing a pressure to be exerted between the electrodes, thus pushing the electrodes together extending the surface area of the dielectric elastomer portion in its plane of operation. Additional aspects of exemplary dielectric elastomers as may be utilized in embodiments of the present invention may be found in U.S. Patent No. 6,545,384 (Pelrine et al.), and in U.S. Patent Application Publication No. US 2002/0130673 (Pelrine et al.), which are both incorporated herein by reference for all purposes.

[0032] Referring again to Figures 1 and 2 A, one or more of the rubber plates 32 of actuator configuration 14 may be adhered to an inner surface of tire structure 12, such as to interior crown surface 24. This location is generally well- suited for purposes of the present technology, although it should be appreciated that actuator configuration 14 may also be mounted to a location such as an interior sidewall surface 26. Further, actuator configuration 14 could be mounted and cured within tire structure 12, for example, between the carcass and inner liner provided along surfaces 24 and/or 26. In accordance with the variety of possible locations for actuator configuration 14, it should be understood that the term "integrated" generally encompasses all possible locations, including being mounted on or in a tire structure. The integration of actuator 14 is facilitated by choosing a material for rubber plates 32 that is compatible for curing with the material(s) of tire structure 12. Attaching the dielectric elastomer portions 30 to the rubber plates 32 of actuator 14 is also facilitated since the outer electrodes of the elastomer portions 30 may be made of a graphite or carbon black material compatible with the rubbers often utilized in tire structure 12 and rubber plates 32. Although not illustrated in Figures 1 and 2A, it should be appreciated that some embodiments of actuator configuration 14 may correspond to dielectric elastomer portions 30 completely encased in a rubber package as opposed to being provided between opposing plates.

[0033] The tire assembly 10 of Figures 1 and 2 A is provided with dielectric elastomer actuator configuration 14 that is adapted to provide adjustable cavity resonance when pneumatic tire structure 12 attains undesirable vibrational modes during operation. One or more characteristics of the tire structure 12 and corresponding tire performance (e.g., temperature, pressure, vibration or noise levels, etc.) can be monitored by the appropriate sensory equipment. Based on the monitored tire characteristics, the width between rubber plates 32 of actuator configuration 14 may be selectively adjusted to optimize one or more of the characteristics. If resonant modes of the mechanical tire system 10 can be changed, more vibrational energy will be attenuated and there will be less noise, heat and vibration apparent to a vehicle operator. Such results will help to prolong tire life and add to overall comfort and performance of a vehicle. Additional details of exemplary circuitry for interfacing with actuator configuration 14 to more effectively monitor and control the operation thereof will be discussed later with respect to Figure 7.

[0034] Yet another exemplary embodiment of a tire assembly with integrated features for adjusting the resonance characteristics of a tire is embodied by tire assembly 10' of Figure 4. Tire assembly 10' includes a pneumatic tire structure 12 as previously defined in Figure 1 and with similar features represented by like reference numerals. A dielectric elastomer actuator configuration 40 is provided as a variable volume cavity. By adjusting the volume of the configuration 40, resonant modes of a tire can be dampened when they near undesirable levels. This is similar in principle to the actuator configuration of Figure 1, although quite different in overall form.

[0035] The actuator configuration 40 of Figure 4 is depicted in more detail in Figure 5. Dielectric elastomer actuator configuration 40 includes a plurality of dielectric elastomer sheets 42 (each similar in configuration to the dielectric elastomer portion illustrated in Figure 3A) that are fastened together to form a three-dimensional cavity. The variable volume cavity may or may not have a bottom surface and is integrated with an interior surface of tire structure 12. Such integration may be as previously described with the integration of actuator configuration 14. Figure 5 also illustrates how the volume formed by actuator configuration 40 can change positions, thus providing an example of its variable volume capabilities. Actuator configuration at an exemplary position 40a (represented by solid lines) illustrates the configuration with no charge applied to the dielectric elastomer sheets, while position 40b (represented by dashed lines) illustrates the configuration when a charge is applied to one or more of the dielectric elastomer portions.

[0036] A still further embodiment of the present technology, including features for adjusting the resonance characteristics of a tire is represented by tire assembly 10" of Figure 6. Tire assembly 10" includes a pneumatic tire structure 12 with similar portions as previously described with respect to Figure 1. A dielectric elastomer actuator configuration 50 includes a plurality of dielectric elastomer portions 52 that are attached between predetermined distal locations on the inner surface of tire structure 12. In one embodiment, respective ends of each dielectric elastomer portion 52 are attached to opposing sidewall surfaces of tire structure 12. In one embodiment, dielectric elastomer portions 52 correspond to dielectric elastomer cords formed from rolled sheets of dielectric elastomer material (such as depicted in Figure 3D), although other dielectric elastomer configurations may also be employed. [0037] By attaching dielectric elastomer portions 52 between opposing sidewall surfaces, the actuator configuration 50 not only allows for disruption of the cavity resonance of tire structure 12, but also is adapted to adjust the sidewall stiffness of the tire. The ability to affect tire sidewall stiffness enables many aspects of tire performance to simultaneously be affected. Adjustment of sidewall stiffness can affect such characteristics as the amount of air pressure in the tire, the comfort level during vehicle operation, the contact patch size of the tire, etc. For example, if the tire encounters a sandy or muddy surface, the size of the contact patch could be made wider thus improving tire traction. Likewise, the size of the contact patch could be made narrower to reduce rolling resistance and improve overall fuel efficiency. Toggling between one or more contact patch sizes may be made possible by interfaced electronics and selectable user options.

[0038] Referring now to Figure 7, exemplary electronic components for interfacing with the exemplary dielectric elastomer actuator configurations of the present technology are presented. The dielectric elastomer actuator illustrated in Figure 7 may correspond to any of the exemplary configurations 14, 40 or 50 as already described. One or more electrodes of each distinct dielectric elastomer portion in dielectric elastomer actuator 14/40/50 is preferably coupled to a charge source 54 that provides a voltage level to the respective dielectric elastomer portions. Charge source 54 may correspond to a variety of different devices, including a battery, rechargeable capacitor, or piezoelectric structure configured to generate electric charge upon mechanical movement of a tire assembly. In some embodiments, a combination of the aforementioned exemplary charge sources may be utilized. For example, a piezoelectric structure could generate electric charge that is then stored in a rechargeable capacitor and then selectively applied to the actuator 14/40/50. When not enough charge is generated by the piezoelectric structure and/or capacitor, then a battery could be utilized as the charge source from which voltages may be selectively applied to actuator 14/40/50.

[0039] Referring still to Figure 7, the amount of charge applied to actuator 14/40/50 from charge source 54 may be controlled by a microcontroller 56. Microcontroller 56 may determine the amount of charge based on inputs received from one or more condition-responsive devices 58. Condition-responsive device 58 may correspond to a sensor, acoustic wave device, or other electronic component whose output varies depending on changes in input conditions. Condition-responsive device 58 may be adapted to sense such characteristics as tire temperature, pressure, vibrational or noise levels, etc. Depending on the output of condition-responsive device 58, microcontroller 56 communicates with charge source 54 such that an appropriate level of voltage is automatically applied to the dielectric elastomer portions of actuator 14/40/50 to optimize the measured characteristics. Microcontroller 56 may be preprogrammed to perform certain predetermined adjustments to the level of charge applied by charge source 54 to actuator 14/40/50 or may be configured to operate based on selective user input. When user inputs are available (such as via user input interface 60), those inputs may select the voltage levels applied from charge source 54 or may set the levels of readings from condition- responsive device 58 that warrant selective application of charge by microcontroller 56. User input interface 60 may correspond to an interface as simple as a toggle switch or to a peripheral computer by which the user can enter information for programming the microcontroller 56.

[0040] Referring still to Figure 7, reference will now be made to additional optional features for use in embodiments of the present invention when dielectric elastomer configurations are utilized not only to provide selective actuation, but also to harvest electrical energy from the dielectric elastomer configurations. Dielectric elastomer portions of the disclosed actuator configurations convert applied electrical forces to resultant mechanical forces. However, dielectric elastomers are typically capable of functioning as transducers that are also capable of converting mechanical energy into electrical energy. Since a tire structure will undergo a substantial amount of mechanical vibrations during vehicle operation, those mechanical vibrations can cause mechanical deformation of the dielectric elastomer portions integrated within the tire structure. When mechanical deformation of dielectric elastomer portions results in generated electric charge, an energy storage device 62 may be provided to collect generated charge therein. The charge stored in energy storage device 62 may then be utilized in conjunction with or as a replacement for charge source 52 from which to selectively apply voltage to the actuators 14/40/50. The power from energy storage device 62 may also be used to power such components as microcontroller 56. When the energy storage device 62 is used in conjunction with charge source 54, both such components can be coupled to microcontroller 56 so that the voltage levels applied to dielectric elastomer actuator 14/40/50 can be regulated.

[0041] hi some embodiments, energy storage device 62 may correspond to an electrolytic capacitor, although other types of capacitors including super capacitors and others may be utilized. Other exemplary energy storage devices may correspond to rechatrgeable batteries. Supplemental power harvesting circuitry (not illustrated) may also be provided in conjunction with energy storage device 62 to yield a conditioned power source for interfacing with certain other electronic components. It should be appreciated that the variety and type of electronic components that may be coupled to the circuitry represented in Figure 7 may be quite diverse, and the present subject matter should not be limited to only those components disclosed herein.

[0042] While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

WHAT IS CLAIMED:

1. A tire assembly with integrated features for adjusting the cavity resonance thereof, said tire assembly comprising: a pneumatic tire structure characterized by a crown having an exterior tread portion for making contact with a ground surface, bead portions for seating said tire to a wheel rim, sidewall portions extending between each bead portion and the crown, and interior crown and sidewall surfaces; a dielectric elastomer actuator configuration integrated at selected locations along the interior crown and sidewall surfaces of said pneumatic tire structure and comprising at least one dielectric elastomer portion, wherein the at least one dielectric elastomer portion includes a layer of elastomeric material provided with first and second electrodes on opposing surfaces thereof; and a charge source coupled to selected of the first and second electrodes of said dielectric elastomer actuator configuration for selectively applying voltage to the at least one dielectric elastomer portion, thus capable of adjusting the effective surface area of the at least one dielectric elastomer portion.

2. The tire assembly of claim 1, wherein said dielectric elastomer actuator configuration comprises two or more rubber plates and a plurality of dielectric elastomer portions attached between the rubber plates and configured to selectively adjust the width between the rubber plates based on the voltage amounts applied from said charge source.

3. The tire assembly of claim 2, wherein said two or more rubber plates form a complete enclosure around the plurality of dielectric elastomer portions.

4. The tire assembly of claim 3, wherein said plurality of dielectric elastomer portions comprise one or more of a dielectric elastomer sheet configuration, a folded dielectric elastomer sheet configuration, a pleated dielectric elastomer sheet configuration and a rolled dielectric sheet configuration.

5. The tire assembly of claim 1, wherein said dielectric elastomer actuator configuration comprises one or more integrated dielectric elastomer sheets formed to define a volumetric region for attaching to an interior surface of said pneumatic tire structure, wherein the volumetric region formed by the one or more integrated dielectric sheets is variable depending on the amount of voltage applied from said charge source to said one or more integrated dielectric elastomer sheets.

6. The tire assembly of claim 1, wherein said dielectric elastomer actuator configuration comprises a plurality of dielectric elastomer portions attached between opposing interior sidewall surfaces of said pneumatic tire structure.

7. The tire assembly of claim 6, wherein said plurality of dielectric elastomer portions comprise one or more of a dielectric elastomer sheet configuration, a folded dielectric elastomer sheet configuration, a pleated dielectric elastomer sheet configuration and a rolled dielectric sheet configuration.

8. The tire assembly of claim 1, further comprising a microcontroller coupled to said charge source and configured to monitor and regulate the amount of voltage applied from said charge source to said at least one dielectric elastomer portion.

9. The tire assembly of claim 8, further comprising a condition-responsive device coupled to said microcontroller for sensing at least one predetermined characteristic associated with said pneumatic tire structure and to facilitate the regulation of a variable amount of voltage to be applied from said charge source to said at least one dielectric elastomer portion.

10. The tire assembly of claim 8, further comprising a user input interface coupled to said microcontroller for providing selectable input to adjust the variable levels of voltage applied from said charge source to said at least one dielectric elastomer portion.

11. The tire assembly of claim 1 , wherein said charge source comprises one of a battery, a rechargeable capacitor and a piezoelectric device.

12. A method of adjusting the cavity resonance of a tire structure, said method comprising the following steps: providing at least one dielectric elastomer portion along selected interior surface locations of a tire structure; monitoring at least one predetermined characteristic associated with the tire structure; and selectively applying electric charge to said at least one dielectric elastomer portion, wherein the amount of electric charge applied to said at least one dielectric elastomer portion is dependent on the monitored levels of the at least one predetermined characteristic and wherein the amount of electric charge applied to said at least one dielectric elastomer portion determines an amount of mechanical deflection of the at least one dielectric elastomer portion resulting in adjustment of the resonance characteristics of the tire structure.

13. The method of claim 12, wherein said at least one predetermined characteristic associated with a tire structure comprises one of temperature, pressure, vibrational levels, and noise levels.

14. The method of claim 12, further comprising a step of regulating the amount of electric charge applied to the at least one dielectric elastomer portion by way of a microcontroller coupled to a charge source and to a condition-responsive device for monitoring the at least one predetermined characteristic.

15. The method of claim 12, further comprising a step of providing user input to indicate the selective amounts of electric charge to apply to said at least one dielectric elastomer portion.

16. The method of claim 12, wherein said step of providing at least one dielectric elastomer portion more particularly comprises providing two or more rubber plates and a plurality of dielectric elastomer portions attached between the rubber plates and configured to selectively adjust the width between the rubber plates based on voltage amounts selectively applied to the plurality of dielectric elastomer portions.

17. The method of claim 12, wherein said at least one dielectric elastomer portion comprises one or more of a dielectric elastomer sheet configuration, a folded dielectric elastomer sheet configuration, a pleated dielectric elastomer sheet configuration and a rolled dielectric sheet configuration.

18. The method of claim 12, wherein said step of providing at least one dielectric actuator more particularly comprises providing one or more integrated dielectric elastomer sheets formed to define a volumetric region for attaching to an interior surface of a tire structure, wherein the volumetric region formed by the one or more integrated dielectric sheets is variable depending on the amount of voltage selectively applied to the one or more integrated dielectric elastomer sheets.

19. The method of claim 12, wherein said step of providing at least one dielectric actuator more particularly comprises providing a plurality of dielectric elastomer portions attached between opposing interior sidewall surfaces of a tire structure.

20. A tire assembly with integrated features for adjusting tire sidewall stiffness and for harvesting electrical energy, said tire assembly comprising: a pneumatic tire structure characterized by a crown having an exterior tread portion for making contact with a ground surface, bead portions for seating said tire to a wheel rim, sidewall portions extending between each bead portion and the crown, and interior crown and sidewall surfaces; a plurality of dielectric elastomer portions attached between selected interior surfaces of said pneumatic tire structure, wherein each of said plurality of dielectric elastomer portions includes a layer of elastomeric material provided with first and second electrodes on opposing surfaces thereof, said dielectric elastomer portions adapted to generate electrical energy upon the application of mechanical forces thereto and to experience mechanical deformation upon application of electrical energy thereto; and at least one energy storage device coupled to selected of the first and second electrodes of each dielectric elastomer portion, said energy storage device configured to store electrical energy generated by the plurality of dielectric elastomer portions and to apply electric charge to the dielectric elastomer portions when variable levels of mechanical deformation are desired.

21. The tire assembly of claim 20, wherein said plurality of dielectric elastomer portions comprise respective sheets of dielectric elastomer material rolled into a cord configuration, each respective sheet comprising an elastomeric material provided with first and second electrodes on opposing surfaces thereof.

22. The tire assembly of claim 20, wherein the first and second electrodes of each dielectric elastomer portion comprise one of carbon black and graphite.

23. The tire assembly of claim 20, wherein said at least one energy storage device comprises a battery or a rechargeable capacitor.

24. The tire assembly of claim 20, wherein selective application of electric charge to the plurality of dielectric elastomer portions affects the sidewall stiffness and corresponding contact patch size of said pneumatic tire structure.

25. The tire assembly of claim 20, further comprising a microcontroller coupled to said energy storage device and configured to monitor and regulate the amount of voltage applied from said energy storage device to said plurality of dielectric elastomer portions.

26. The tire assembly of claim 25, further comprising a condition-responsive device coupled to said microcontroller for sensing at least one predetermined characteristic associated with said pneumatic tire structure and to facilitate the regulation of a variable amount of voltage to be applied from said energy storage device to said plurality of dielectric elastomer portions.

27. The tire assembly of claim 25, further comprising a user input interface coupled to said microcontroller for providing selectable input to adjust the variable levels of voltage applied from said energy storage source to said plurality of dielectric elastomer portions.