WO2007040536A2

WO2007040536A2 - System and method for harvesting electric power from a rotating tire’s acoustic energy

Info

Publication number: WO2007040536A2
Application number: PCT/US2005/035705
Authority: WO
Inventors: John David Adamson; George Phillips O'brien
Original assignee: Michelin Recherche Et Technique S.A.; Societe De Technologie Michelin
Priority date: 2005-10-03
Filing date: 2005-10-03
Publication date: 2007-04-12
Also published as: WO2007040536A3; TW200714492A

Abstract

A tire assembly with energy harvesting capabilities includes a tire structure and an acoustic-electric transducer configured to convert acoustic energy generated upon movement of the tire structure to electrical energy. An example of an acoustic-electric transducer corresponds to a microphone including a membrane that vibrates upon subjection to sound waves, a magnet and a wire coil surrounding at least a portion of the magnet. The transducer serves to produce an electric current in the wire coil that is coupled to additional power conditioning elements such as a rectifier, an energy storage device (e.g., capacitor or rechargeable battery) and a voltage regulator. Sufficient accumulations of harvested energy can then power tire electronic systems, including various condition-responsive devices (i.e., sensors, etc.) a revolution counter, a radio frequency (RF) device, a rechargeable battery or a lighting device.

Description

PCT PATENT APPLICATION TITLE; SYSTEM AND METHOD FOR HARVESTING ELECTRIC

POWER FROM A ROTATING TIRE'S ACOUSTIC ENERGY FIELD OF THE INVENTION

[0001] The present invention generally concerns tire electronics assemblies that are self-powered via acoustic energy that is generated during conventional tire rotation. More particularly, a tire structure is adapted with an acoustic-electric transducer, such as a microphone, for converting acoustic energy generated during tire rotation along a ground plane into electrical energy. Power conditioning or power storage elements may be coupled to the acoustic-electric transducer, and sufficient accumulations of harvested energy can then power tire electronic systems, including various condition-responsive devices (i.e., sensors, etc.), radio frequency (RF) transmitters, and other components.

BACKGROUND OF THE INVENTION

[0002] The incorporation of electronic devices with tire structures yields many practical advantages. Tire electronics may include sensors and other components for relaying tire identification parameters and also for obtaining information regarding various physical parameters of a tire, such as temperature, pressure, number of tire revolutions, vehicle speed, etc. Such performance information may become useful in tire monitoring and warning systems, and may even potentially be employed with feedback systems to regulate proper tire pressure levels.

[0003] U.S. Patent No. 5,749,984 (Frey et alΛ discloses a tire monitoring system and method that is capable of determining such information as tire deflection, tire speed, and number of tire revolutions. Another example of a tire electronics system can be found in U.S. Patent No. 4,510,484 (Snyder), which concerns an abnormal tire condition warning system. U.S. Patent No. 4,862,486 (Wing et aU also relates to tire electronics, and more particularly discloses an exemplary revolution counter for use in conjunction with automotive and truck tires. Examples of aspects of tire pressure monitoring systems are disclosed in U.S. Patent Nos. 4,004,271 (Haven et alΛ. 4,742,857 (Gandhi), 5,616,196 (Loewe), and 5,928,444 (Loewe et aL).

[0004] Yet another potential capability offered by electronics systems integrated with tire structures corresponds to asset tracking and performance characterization for commercial vehicular applications. Commercial truck fleets, aviation crafts and earthmover/mining vehicles are all viable industries that could utilize the benefits of tire electronic systems and related information transmission. Tire sensors can determine the distance each tire in a vehicle has traveled and thus aid in maintenance planning for such commercial systems. Vehicle location and performance can be optimized for more expensive applications such as those concerning earth mining equipment. Entire fleets of vehicles could be tracked using RF tag transmission, exemplary aspects of which are disclosed in U.S. Patent No. 5,457,447 (Ghaem et aU.

[0005] Such integrated tire electronics systems have conventionally been powered by a variety of techniques and different power generation systems. Examples of mechanical features for generating energy from tire movement are disclosed in U.S. Patent Nos. 4,061,200 (Thompson) and 3,760,351 (Thomas). Such examples provide bulky complex systems that are generally not preferred for incorporation with modern tire applications. Yet another option for powering tire electronics systems is disclosed in U.S. Patent No. 4,510,484 (Snyder), which concerns a piezoelectric reed power supply symmetrically configured about a radiating center line of a tire.

[0006] Another typical solution for powering tire electronics systems corresponds to the use of a non-rechargeable battery, which inherently provides an inconvenience to the tire user since proper electronics system operation is dependent on periodic battery replacement. Conventional batteries also often contain heavy metals that are not environmentally friendly and which present disposal concerns, especially when employed in highly numerous quantities. Still further, batteries tend to deplete their energy storage quite rapidly when powering electronic applications characterized by complex levels of functionality. Battery storage depletion is especially prevalent in electronic systems that transmit information over a relatively far distance such as from truck wheel locations to a receiver in the truck cabin. Even when batteries are used in electronics systems that transmit from wheel locations to a closer receiver location, information is then typically relayed via hard-wire transmission medium from the RF receiver location to the vehicle cab thus requiring the installation of additional and often expensive communications hardware in a vehicle.

[0007] Yet another known method for deriving power for tire monitoring systems relates to scavenging RF beam power with an interrogation antenna in close proximity to a tire and integrated electronic features. Energy that is radiated from the antenna is scavenged to power the electronics, which must often be very specialized ultra-low-power electronics limited to within a few microwatts. Interrogation antennas employed in conjunction with beam-powered electronics must typically be placed in relatively close proximity (within about two feet) to each wheel well due to limited transmission ranges. This typically requires multiple interrogation antennas per vehicle, thus adding to potential equipment costs. Each antenna is also quite susceptible to damage from road hazards, and thus for many reasons may not be the most desirable solution for powering certain tire electronic applications.

[0008] Many known methods for harvesting power and providing power to tire electronics systems exist. While various such methods and systems have been developed, no design appears to have emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology. The disclosures of all the foregoing United States patents are hereby incorporated into this application for all purposes by virtue of reference thereto.

SUMMARY OF THE INVENTION

[0009] hi view of the recognized features encountered in the prior art and addressed by the present subject matter, an improved system and method for powering electronic systems integrated within a tire structure has been developed. A tire assembly may incorporate an acoustic-electric transducer for converting acoustic energy generated during tire rotation to electrical energy which may then be conditioned and/or stored. Sufficient accumulations of such stored energy can then power various electronic components associated with a tire assembly, such as rechargeable batteries, various condition-responsive devices and radio frequency (RF) transceivers.

[0010] hi accordance with more particular aspects of the disclosed technology, it is an object of the present subject matter to provide a tire or wheel assembly with integrated self-powered electronic components. Such electronic components receive power from electric charge stored as a result of harvested acoustic energy from within a wheel assembly, and may correspond to a variety of devices such as a rechargeable battery, a revolution counter, an active RFID transponder, etc. A still further electronic application concerns an electronics assembly designed to measure and transmit information regarding tire conditions such as pressure and temperature, as well as other information such as the number of tire revolutions or general tire identification variables.

[0011] hi accordance with additional aspects of the disclosed technology, it is an object of the presently disclosed technology to provide a power generation device for tire electronic components that employs an acoustic-electric transducer, such as but not limited to a microphone, for harvesting electrical energy from acoustic energy in a tire or wheel assembly. By conditioning and storing the harvested energy, a power source for tire electronic components is effected.

[0012] Various features and aspects of the subject tire electronics system and specialized power harvesting technology offer a plurality of advantages. The disclosed technology provides for a self-powered tire electronics system that is not dependent on replacement of batteries. Although batteries and battery-operated devices may still be incorporated with aspects of the present subject matter, many complications regarding tire electronics that are solely powered by batteries are obviated in accordance with the disclosed technology.

[0013] Another advantage of the present subject matter is that a tire monitoring system is provided that reduces the amount of required signal hardware relative to conventional tire monitoring systems. By providing a tire monitoring system that is self-powered, no scavenger antennas or multiple receiver locations with additional hardwire connections are required. Components of such a tire monitoring system can be integrated within each individual tire structure on a given vehicle such that a single receiver (typically located in a vehicle cabin) is capable of acquiring information transmitted by each tire's integrated electronics.

[0014] Yet another advantage of the present subject matter is that there are fewer limitations regarding the type and amount of electronic equipment capable of utilization within tire and wheel assembly structures. Tire electronics powered by some conventional methods are often limited to ultra-low power devices. Devices in accordance with the disclosed technology are not necessarily subject to such extreme power limitations. This advantage further facilitates greater functionality of tire electronics, as more components and/or higher-level equipment may potentially be utilized.

[0015] A still further advantage of the present subject matter is that the disclosed system and method for generating power and utilizing such power can be used in accordance with a variety of existing applications. Measurement capabilities, monitoring and warning systems, vehicle feedback systems, and asset tracking potential may be possible for applications such as commercial truck fleets, airplanes, and mining/earthmover equipment.

[0016] In one exemplary embodiment of the present subject matter, a tire assembly with energy harvesting capabilities includes a tire structure and an acoustic- electric transducer. The tire structure may be characterized by a crown having an exterior tread portion for making contact with a ground surface. The acoustic-electric transducer is integrated with the tire structure and is configured to convert acoustic energy generated upon movement of the tire structure to electrical energy.

[0017] In more particular embodiments of the above-referenced tire assembly, the acoustic-electric transducer corresponds to a microphone. In another embodiment, the transducer includes a membrane configured to vibrate upon subjection to sound/pressure waves coupled to a magnet surrounded by a wire coil. These power generation elements may be coupled to a power conditioning module that selectively includes a voltage rectifier, an energy storage device (such as a capacitor or rechargeable battery) and/or a voltage regulator. Once energy is harvested from a tire's acoustic energy, it may be used to power other components associated with a tire, such as a condition-responsive device, a radio frequency (RF) transmitter, a microcontroller, a revolution counter, a rechargeable battery, a light assembly, a global positioning system (GPS), etc.

[0018] The subject tire assemblies may be employed with conventional pneumatic tire structures or alternatives such as tires with support structures configured for operation in potential run-flat modes or non-pneumatic structurally supported tires. Additional embodiments of the subject technology may not necessarily be limited to the combination of a tire structure and acoustic-electric transducer. More particularly, it should be appreciated that embodiments of the subject technology may include power generation features and optional electronic components which may be provided as a modular assembly that may later be retrofit to tire structures or to associated wheel assemblies. [0019] 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.

[0020] 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

[0021] 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:

[0022] Figure 1 displays a generally cross-sectional view of an exemplary pneumatic tire structure;

[0023] Figure 2 provides an illustration of exemplary features of an acoustic-electric transducer for use in a power generation device of the presently disclosed technology;

[0024] Figure 3 provides a schematic representation of an exemplary power generation device in accordance with aspects of the present subject matter, including exemplary power conditioning circuitry; [0025] Figure 4A provides a block diagram representation of exemplary self-powered electronics including a power generation device and a tire electronics assembly and exemplary interaction thereof in accordance with the present subject matter;

[0026] Figure 4B provides a block diagram representation of exemplary integrated self-powered electronics including a power generation device and a tire electronics assembly and alternative exemplary interaction thereof in accordance with the present subject matter;

[0027] Figure 5 provides a block diagram representation of an exemplary tire electronics assembly in accordance with the disclosed technology;

[0028] Figure 6 provides a block diagram representation of an exemplary remote receiver configuration in accordance with the present subject matter;

[0029] Figure 7 provides an axial half-sectional view of a tire having a safety support mounted on a wheel rim inside the tire and with integrated self- powered electronics in accordance with the present subject matter;

[0030] Figure 8 provides an axial half-sectional view of the tire and safety support of Figure 7 in which the safety support is in the run-flat condition; and

[0031] Figure 9 provides a side plan view of an exemplary non-pneumatic structurally supported tire with integrated self-powered electronics in accordance with the present subject matter.

[0032] 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

[0033] As discussed in the Brief Summary of the Invention section, the present subject matter is particularly concerned with a system and method for harvesting power within a tire structure from incident acoustic energy. Acoustic energy is converted to electrical energy which can then be used to power electronic systems, examples of which include components for identifying various physical tire parameters as well as radio frequency (RF) transmission devices and others.

[0034] Selected combinations of the aforementioned aspects of the disclosed technology correspond to a plurality of different embodiments of the present subject matter. It should be noted that each of the exemplary embodiments presented and discussed herein should not insinuate limitations of the present subject matter. Features or steps illustrated or described as part of one embodiment may be used in combination with aspects of another embodiment to yield yet further embodiments. Additionally, certain features may be interchanged with similar devices or features not expressly mentioned which perform the same or similar function. Similarly, certain process steps may be interchanged or employed in combination with other steps to yield additional exemplary embodiments of a method for generating electric power from a rotating tire's acoustic energy.

[0035] The capabilities of the subject power harvesting features, as hereafter presented, offer numerous advantages over conventional techniques for providing power within a tire assembly. Antenna beam power scavenging techniques, as previously discussed, are no longer one of limited options to choose from for powering tire electronics. As such, the functional capabilities of many types of tire electronics is generally increased. The option of utilizing batteries for power generation is no longer essential, thus avoiding costly and cumbersome battery replacement. Although the presently disclosed technology provides for power harvesting technology that enables antenna beam power and batteries to be eliminated, it should be appreciated that power harvesting features could include a hybrid combination of storing channeled static electricity and/or batteries and/or antenna beam scavenging to power different selected electronic components within a wheel assembly.

[0036] Referring now to Fig. 1, a tire assembly including a conventional pneumatic tire structure 10 is characterized by a crown 15 which supports an exterior tread portion 18 and sidewalls 20 that extend to bead portions 22. Sidewalls 20 generally extend between section lines 17 and 19 and the tire crown 15 generally extends between the two section lines 19. Tire beads 22 are provided such that the tire structure 10 can be effectively seated to and secured on 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 23 extends between beads 22 across sidewall portions 20 and crown 15, and under inflation pressure defines the tire's shape and transmits forces for traction and steering. Belt package 21 is provided within tire structure 16 generally along the crown 15. As an inflated tire rotates on a vehicle wheel, at least some portion of the exterior tread surface is preferably in continuous contact with a ground surface. [0037] An electronics assembly 12 may be mounted to or integrated with tire structure 10 and may generally include a power generation device and/or additional electronic components that may be powered by the power generation device, both which will be discussed later in additional detail. As illustrated in Fig. 1, electronics assembly 12 may be mounted to the interior crown surface (or inner liner) of tire structure 10, although it should be appreciated that electronics package 12 or select components thereof may also be mounted to other locations within the tire structure or on an associated wheel assembly to which the tire may be mounted. For example, in some embodiments, at least the acoustic-electric transducer of the power generation device is mounted on the wheel rim to which tire structure 10 is mounted. In other embodiments, the acoustic-electric transducer may be mounted on the tire valve.

[0038] Selected elements of electronics assembly 12 (especially power conditioning electronics or powered electronic components) may be provided in or on an additional rubber or elastomer support before being adhered to or embedded in the tire, valve, wheel rim, etc. to provide additional protection for such components, hi accordance with the variety of possible locations for select components of electronics assembly 12, it should be understood that the term "integrated" relative to a tire structure generally encompasses all possible locations, including being mounted on or in a tire structure.

[0039] The subject power generation technology may also be utilized in non- conventional tires, in other words, tires having variations to the exemplary structure illustrated in Figure 1. hi one example, the power generation technology disclosed herein may be incorporated into tires having safety support features mounted inside their tires on their wheel rims in order to take up load in the event of tire failure, thus supporting the tread strip of the tire in the event of a loss of inflation pressure. Figures 7 and 8 are now discussed to illustrate aspects of such a tire with safety support features. Figure 7 provides an axial half-sectional view of a safety support 150 mounted around a preferential wheel rim 152 and inside the cavity 154 of a corresponding tire 156. The tire 156 is designed to be mounted on the wheel rim 152 and in particular has two beads of different diameters. The support 150 has three main parts: a base 158 of annular overall shape and reinforced with a ply 160 oriented longitudinally at substantially zero degrees, a substantially annular cap 162 with longitudinal grooves 164 in its radially outer wall, and an annular body 166 for joining the base 158 and the cap 162 together. The cavity defined by portion 168 makes it possible to reduce the weight of support 150 as well as provide in conjunction with the other portions of support 150 to give uniform support under run- flat conditions (i.e., under full or partial loss of tire pressure). Figure 8 shows a safety support similar to that of Figure 7 while it is in operation along a ground surface, e.g., during a run-flat condition. The cap 162 of the support 150 is in contact with the radially inner surface of the cap of the tire 156, thus preventing the tire 156 from riding on the wheel rim 152 during loss of air pressure in tire cavity 154. Additional details of such a tire with safety support are disclosed in U.S. Patent No. 5,891,279 (Lacour), which is incorporated by reference herein for all purposes. It should be appreciated that other specific safety supports may be integrated within a tire structure. Although the support disclosed in Lacour is a generally solid circular device, other support embodiments could be made of other support materials (e.g., foam rubber that undergoes deformation when the tire is in a run-flat mode.

[0040] Referring still to Figures 7 and 8, an acoustic-electric transducer or other select portions of the subject power generation device may be integrated with the safety support 150 of such exemplary run-flat tire structures. For example, power generation device components may be integrated with the cap portion of safety support 150, for example between one of the grooves 164. An alternative mounting location may correspond to an inner surface of the area defined by cavity 168. It should be appreciated that power generation device components may be mounted on, attached to or embedded in still further locations relative to a tire having a safety support feature for facilitating run-flat operation while remaining with the spirit and scope of the present invention.

[0041] Yet another example of a tire with which the subject piezoelectric technology may be utilized is a structurally supported tire different than that described with reference to Figures 7 and 8. A non-pneumatic structurally supported tire will now briefly be described with reference to Figure 9. The non-pneumatic tire 170 of Figure 9 is designed to support a load solely with its structural components and, contrary to the mechanism of conventional pneumatic tires, without support from internal air pressure. Structurally supported non-pneumatic tire 170 has a ground contacting tread portion 172, a reinforced annular band 174 disposed radially inward of the tread portion, a plurality of web spokes 176 extending transversely across and radially inward from the annular band, and a mounting band 178 at the radially inner end of the web spokes. The mounting band 178 anchors the tire 170 to a wheel 180 or hub. Although not illustrated in Figure 9, an additional plurality of web spokes may extend in the equatorial plane. The reinforced annular band 174 may more particularly include an elastomeric shear layer, a first membrane adhered to the radially innermost extent of the elastomeric shear layer, and a second membrane adhered to the radially outermost extent of the elastomeric shear layer. The membranes have a tensile stiffness that is greater than the shear stiffness of the shear layer so that the reinforced annular band undergoes shear deformation under load. The reinforced annular band 174 supports loads on the tire. As indicated in Figure 9, a load L placed on the tire axis of rotation X is transmitted by tension in the web spokes 176 to the annular band 174. The annular band 174 acts in a manner similar to an arch and provides a circumferential compression stiffness and a longitudinal bending stiffness in the tire equatorial plane sufficiently high to act as a load- supporting member. Under load, the annular band deforms in contact area C with the ground surface through a mechanism including shear deformation of the band. The ability to deform with shear provides a compliant ground contact area C that acts similar to that of a pneumatic tire, with similar advantageous results. Additional details of a structurally supported non-pneumatic tire such as illustrated with respect to Figure 9 are disclosed in U.S. Patent Application Publication 2004/0159385, which is incorporated herein by reference for all purposes.

[0042] Referring still to Figure 9, an acoustic-electric transducer or other portions of the subject power generation device may be integrated with the structurally supported non-pneumatic tire 170. For example, electronic components may be integrated at the interior of the ground-contacting tread portion 172, at the interior of the reinforced annular band 174, or on one or more of the web spokes 150. Power generation electronics may be mounted on, attached to or embedded in still further locations relative to a structurally supported non-pneumatic tire while remaining with the spirit and scope of the present invention.

[0043] Referring now to more particular components of an electronics assembly 12 of the presently disclosed technology, such assembly may include a power generation device (PGD) 16 as well as a tire electronics system (TES) 18. (See Figs. 4A and 4B.) PGD 16 may include components for conditioning and storing generated power and TES 18 may include one or more additional electronic components that are powered by the harvested energy from the power generation device. More particular aspects of the power generation features of electronics assembly 12 will now be presented.

[0044] With reference to Fig. 2, a power generation device 16 in accordance with aspects of the present subject matter generally includes an acoustic- electric transducer 14 configured to transform acoustic or sound energy incident in a tire structure during vehicle operation into electrical energy, m one embodiment of the present technology, an acoustic-electric transducer 14 correspond to a microphone, although it should be appreciated that other transducer embodiments may be utilized. A particular example of a dynamic microphone embodiment that may be utilized is represented in Fig. 2., although it should be further appreciated that other microphone embodiments may be practiced and fall within the scope of the present invention. Sound waves exist as patterns of air pressure that cause movement of a thin membrane or diaphragm 30. Additional components of the acoustic-electric transducer include a magnet 32 and a wire coil 34 surrounding the magnet 32. Membrane 30 may be directly coupled to either the magnet 32 or to the wire coil 34. Movement of the magnet within the coil causes a change of magnetic flux in the coil which produces current through an electric field. Alternatively, the movement of the coil around the magnet produces an electric field. Since current is produced by the motion of the membrane 30, the amount of generated electric current is determined by the speed of that motion. Wire leads 36a and 36b connect coil 34 to other electronic components in the electronics assembly 12.

[0045] Another portion of a power generation device 16 of the present technology is a power conditioning module, an example of which is presented in Fig. 3. The major functionality of a power conditioning module is to rectify, condition and store the electric energy that is harvested by the power generation device, namely by acoustic-electric transducer 14. hi general, power conditioning modules may be particularly designed for different electronics applications for which power is harvested. In accordance with an exemplary embodiment of a tire monitoring system as disclosed in the present specification, the exemplary power conditioning module of Figure 3 is designed according to certain dynamic energy requirements. In particular, the exemplary power conditioning module of Fig. 3 is designed such that the voltage output 44 is generally about five volts.

[0046] With further reference to the exemplary power conditioning module of Fig. 3, acoustic-electric transducer (represented schematically as a microphone) 14 is connected in parallel with a rectifier, for example a full-bridge rectifier 46. Alternative rectifier configurations could correspond to a doubling rectifier, an N- stage voltage multiplier, or others as appreciated by one of ordinary skill in the art. The rectified signal from rectifier 46 is then stored in an energy storage 48. Examples of suitable components for energy storage device include, without limitation, capacitors such as electrolytic capacitors, tantalum capacitors, super capacitors, or rechargeable batteries. Once a sufficient amount of energy has accumulated in energy storage device 48, a bi-polar transistor 50 acts as a switch to release the stored energy in energy storage device 48 to a voltage regulator 52. An example of a voltage regulator suitable for use in the exemplary embodiment of Fig. 3 is a dual- mode five- volt programmable micropower linear voltage regulator such as the MAX666 brand offered for sale by Maxim Integrated Products. Such a voltage regulator may be well suited for electronics systems that may typically have been battery-powered systems, and is able to convert the voltage across energy storage device 48 to a regulated five volt output voltage 44. Other voltage regulators, such as micropower switching regulators, which often have higher efficiency levels than linear regulators, may also be used in accordance with the disclosed technology. A diffusion metal oxide semiconductor (DMOS) FET transistor 54 and zener diode 56 are additionally provided in the exemplary power conditioning module of Fig. 3. Zener diode 56 is provided in parallel with energy storage device 48 to provide overvoltage protection for the energy storage device 48, by limiting the amount of charge stored therein.

[0047] Initially, transistors 50 and 54 are off, and the ground at the drain of transistor 54 is floating such that no output voltage is provided. As energy storage device 48 charges to a sufficient voltage level (determined by zener diode 56 and the base-emitter junction of transistor 50), transistor 50 turns on, activating transistor 54 and latching transistor 50. At this point, energy storage device 48 is allowed to discharge through the circuitry providing a five volt regulated output 44 to an electronics system. Typically, when the application electronics to which output voltage 44 is supplied has finished its useful work, the electronics system sends a signal back at signal path 58, through resistor 60 and capacitor 62 to turn off transistor 50 and deactivate transistor 54 such that energy can once again begin to accumulate on energy storage device 48.

[0048] Energy that is stored within the power conditioning electronics of Fig. 3 may be applied to a variety of components or different tire electronics assemblies in accordance with the present subject matter. Figs. 4A and 4B, respectively, illustrate exemplary aspects of interaction between power generation device 16 (including optional power conditioning circuitry) and an exemplary tire electronics system (TES) 18.

[0049] In accordance with Fig. 4A, energy is allowed to accumulate on an energy storage device in the power conditioning circuitry of PGD 16 (for example, a capacitor or rechargeable battery) until a sufficient charge has been obtained to perform the desired functions in TES 18. Between power cycles, TES 18 remains unpowered, and thus the activation of TES 18 is governed by the rate at which energy is accumulated in the energy storage device of PGD 16, When sufficient energy is accumulated in the power harvesting circuitry, a supply voltage "V_dd" and ground voltage "V_ss" will be provided at paths 64 and 66 respectively to TES 18. TES 18 will return an "Active" signal along path 58 indicating electronics in TES 18 are currently functioning. When the given electronics in TES 18 are done with their respective tasks, then the "Active" signal goes low and the energy storage device 48 once again accumulates energy. This cycle will repeat as long as a tire assembly rotates at or above a given threshold speed.

[0050] In accordance with the exemplary interaction presented and discussed with reference to Fig. 4B₅ PGD 16 continuously provides voltage "V_dd" and ground "V_ss" signals to TES 18 along with a "Fuel Gage" signal representative of the amount of energy stored in PGD 16. When power is applied to TES 18, a microprocessor or other suitable electronic component can periodically activate itself and monitor the Fuel Gage signal from PGD 16. If a sufficient amount of energy is available in energy storage device 48, then TES 18 will engage in a specified task. If a sufficient amount of energy is not available, then TES 18 will go into a low current mode where it consumes less than about one μA of power. The Fuel Gage signal is thereafter periodically checked until energy accumulation is sufficient. This cycle of waiting for sufficient energy accumulation, engaging in a specified task, and returning to low power mode is preferably repeated in a continuous fashion as long as the tire is rotating at or above a given threshold speed.

[0051] As previously mentioned, TES 18 could comprise a variety of different electronic applications depending on what sort of components are included in a tire or wheel assembly. A specific example of a tire electronics system 18 corresponds to the combination of devices depicted in Fig. 5. In particular, such electronics assembly functions as a tire monitoring system that measures temperature and pressure within a tire structure and sends the results by means of a radio frequency (RF) transmitter 68 to a remote receiver location. An example of respective transmitter and receiver modules for utilization with aspects of the disclosed technology corresponds to respective TX2 and RX2 brand UHF FM Data Transmitter and Receiver Modules such as offered for sale by Radiometrix Ltd.

[0052] A five- volt power signal "V_dd"₅ ground signal "V_ss", and either an "Active" or "Fuel Gage" signal as discussed with reference to Figs. 4A and 4B are preferably provided from PGD 16 to a microcontroller 70. An example of a suitable microcontroller for use with the disclosed technology is a Microchip brand PIC16LF876 28-pin CMOS RISC microcontroller. Microcontroller 70 is activated when power is applied at input path 64 and then applies power to both temperature sensor 72 and pressure sensor 74 (as well as any additional sensors or appropriate electronic devices in TES 18). An example of a temperature sensor 72 suitable for utilization with the disclosed technology is a LM50 SOT-23 Single-Supply Centigrade Temperature Sensor such as offered for sale by National Semiconductor. An example of a pressure sensor 74 suitable for utilization with the disclosed technology is a Model 1471 PC Board Mountable Pressure Sensor such as offered for sale by ICSensors and Measurement Specialties Inc. Alternatively, a surface acoustic wave (SAW) device may be employed to measure both temperature and pressure at a given location. Additional sensors 76, 78 and 80, respectively, may measure additional characteristics of a tire structure or corresponding wheel assembly. In accordance with the present subject matter, a condition-responsive device is intended to include sensors, acoustic devices, and other components that provide some sort of output in response to change in input conditions.

[0053] Yet another component of the exemplary TES embodiment 18 of Fig. 5 corresponds to a rechargeable battery 81 that may also be configured to receive electric charge stored in energy storage device 48 and to store additional energy for the integrated tire electronics or other electronic devices in a vehicle. An example of a rechargeable battery for use with the present subject matter is a LiteStar brand solid- state rechargeable battery such as offered for sale by Infinite Power Solutions. Energy stored in battery 81 can typically be stored for a much longer period of time than in an energy storage device such as a capacitor, thus it may be ideal to use the rechargeable battery or the rechargeable battery in combination with a capacitor. Energy stored in battery 81 can be provided to microcontroller 70 when not enough power is being stored in energy storage generated by actuation of the piezoelectric fibers. Such a situation could occur, for instance, when the vehicle is stationary or when the tires are removed from a vehicle. For example, stored energy may be needed to power TES 18 when a ground crew checks the air pressure in stationary tires on a commercial airliner. Also, battery 81 may serve to provide power to TES 18 such that information for managing tire inventories or retreads is available when a tire is removed from the vehicle.

[0054] With further reference to the exemplary TES embodiment 18 of Fig. 5, microcontroller 70 preferably includes an analog-to-digital (AfD) converter that receives information from sensors 72 through 80, respectively, and converts it to digital information. Microcontroller 70 also comprises memory, preferably nonvolatile EEPROM, which stores a unique identification tag that provides sufficient information to identify the tire or wheel assembly. Such an identification variable may be especially useful in tracking tires and vehicles in commercial applications such as trucking fleets, airplanes, etc. Once the desired information, such as that provided by sensors 72 through 80 respectively, is acquired by microcontroller 70 and converted to digital information, microcontroller 70 preferably shuts off power to the sensors and turns on power to RF transmitter 68 at lines 82 and 84 respectively. The desired digitized information is then output on data line 86 to RF transmitter 68, where the data is modulated onto an FM carrier signal and transmitted via antenna 88 to a remote receiver location.

[0055] Additional embodiments of tire electronics assemblies that may be powered via the subject power harvesting technology may correspond to a combination of many fewer components than the exemplary TES embodiment 18 of Fig. 5 or even to a single component, such as a revolution counter, a single condition- responsive device, a rechargeable battery or a lighting device or assembly.

[0056] A vehicle employing tire assemblies with self-powered electronics that include some sort of transmitter device is preferably equipped with a single receiver for obtaining the wirelessly transmitted information from each tire assembly. Fig. 6 provides a block diagram representation of an exemplary remote receiver configuration 90 in accordance with the present subject matter. Receiver antenna 92 facilitates receipt of information transmitted from each wheel assembly and relays the information to RF receiver 94, where the received information is demodulated from its carrier signal and provided on path 96 to signal processor 98. A carrier detection signal is also provided from RF receiver 94 to signal processor 98 via signal path 100. The data outputted from RF receiver 94 and the carrier detection signal are preferably multiplied together in signal processor 98 such that a signal without spurious noise is obtained. This data signal with reduced error probability is then preferably routed to a driver circuit that converts the digital signal to a signal with voltage levels suitable for transmission via an RS232 interface 102 to a host computer 104. Terminal emulation software is preferably provided at host computer 104 such that the data received via RS232 interface 102 is converted to information readily usable by an end user, such as that provided on a readable display module.

[0057] It should be appreciated in accordance with the disclosed technology that other electronic devices other than those specifically disclosed in the present specification may be utilized with the subject power generation technology. For instance, it may be desired to transmit other types of information other than temperature, pressure and identification to a remote location. Examples include the number of tire revolutions, amount of tire deflection, vehicle speed, and level of static and dynamic forces acting on a tire structure. U.S. Patent No. 5,749,984 discloses other aspects of a tire monitoring system that may be employed with the present subject matter, and such patent is incorporated herein by reference for all purposes. A tire electronics system may be coupled with a global positioning system (GPS) to pinpoint a vehicle's precise location. Harvested power may alternatively be utilized to power light assemblies or feedback systems in a wheel assembly. The number of electronics applications capable of being powered in accordance with aspects of the disclosed technology are vastly numerous and should in no way be limiting to the present subject matter.

[0058] 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 IS:

1. A tire assembly with energy harvesting capabilities, comprising: a tire structure; and an acoustic-electric transducer positioned relative to said tire structure and configured to convert acoustic energy generated upon movement of said tire structure to electrical energy.

2. A tire assembly as in claim 1, wherein said acoustic-electric transducer comprises a microphone.

3. A tire assembly as in an preceding claim, wherein said acoustic-electric transducer comprises: a membrane configured to vibrate upon subjection to sounds waves; a magnet; and a wire coil wound around at least a portion of said magnet; and wherein one of said wire coil and said magnet is coupled to said membrane.

4. A tire assembly as in any preceding claim, further comprising a power conditioning module coupled to said acoustic-electric transducer.

5. A tire assembly as in claim 4, wherein said power conditioning module comprises a voltage rectifier for rectifying a current signal representative of the electrical energy harvested by said acoustic-electric transducer.

6. A tire assembly as in claim 4 or 5, wherein said power conditioning module comprises an energy storage device for storing at least a portion of the electrical energy harvested by said acoustic-electric transducer.

7. A tire assembly as in claim 6, wherein said energy storage device comprises one of a capacitor and a rechargeable battery.

8. A tire assembly as in any of claims 4 through 7, wherein said power conditioning module further comprises a voltage regulator.

9. A tire assembly as in any preceding claim, further comprising at least one electronic component selected from a group consisting of a revolution counter, a condition-responsive device, a rechargeable battery, a flashing light assembly, a microcontroller, a global positioning system (GPS), and a radio frequency (RF) device, and wherein said at least one electronic component is powered by the electric energy harvested by said acoustic-electric transducer.

10. A tire assembly as in any preceding claim, further comprising at least one sensor configured to monitor one or more of tire pressure and tire temperature, wherein said at least one sensor is powered by the electric energy harvested by said acoustic-electric transducer.

11. A tire assembly as in claim 10, further comprising an antenna coupled to said at least one sensor for radiating radio frequency (RF) signals representative of the tire pressure and temperature information determined by said at least one sensor.

12. A tire assembly as in any preceding claim, further comprising a wheel rim to which said tire structure is mounted, and wherein said acoustic-electric transducer is mounted to said wheel rim.

13. A tire assembly as in any preceding claim, wherein said tire structure is 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 pneumatic tire structure to a wheel rim, sidewall portions extending between each bead portion and the crown, an inner liner and a tire valve.

14. A tire assembly as in claim 12, wherein said acoustic-electric transducer is mounted relative to the inner liner of said tire structure.

15. A tire assembly as in claim 12, wherein said acoustic-electric transducer is integrated relative to said tire valve.

16. A tire assembly as in any of claims 1 through 11, wherein said tire structure is a pneumatic tire structure characterized by a crown having a tread portion for making contact with a ground surface, and where said tire assembly further comprises a safety support configured for mounting on a wheel rim inside of said pneumatic tire structure in order to support the tread portion of said pneumatic tire structure in event of a loss of inflation, said safety support comprising an annular body having an inner surface intended to fit around a wheel rim and an outer cap intended to be engaged by the tread portion in event of a loss of pressure.

17. A tire assembly as in claim 16, wherein said acoustic-electric transducer is attached to a portion of said safety support.

18. A tire assembly as in claim 16, wherein said acoustic-electric transducer is integrated with said pneumatic tire structure.

19. A tire assembly as in any of claims 1 through 11, wherein said tire structure comprises a non-pneumatic structurally supported tire comprising a reinforced annular band, a plurality of web spokes extending transversely across and radially inward from the reinforced annular band, and a mounting band at the radially inner end of the web spokes.

20. A tire assembly as in claim 19, wherein said non-pneumatic structurally supported tire further comprises a tread portion disposed on a radially outer extent of the reinforced annular band.

21. A tire assembly as in claim 19 or 20, wherein said acoustic-electric transducer is mounted to the interior of the reinforced annular band of said non- pneumatic structurally supported tire.

22. A tire assembly as in claim 19 or 20, wherein said acoustic-electric transducer is mounted to one or more of the plurality of web spokes of said non- pneumatic structurally supported tire.