Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2002-04-09
2004-05-25
Chapman, John E. (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S146000, C073S660000
Reexamination Certificate
active
06739195
ABSTRACT:
BACKGROUND
A system using insonification senses acoustic energy to establish characteristics of a material. A preferred embodiment of the present invention uses a piezoelectric strip as an acoustical transducer to indicate the relative temperature of a tire while in use.
Modern tires are built using several layers (plies) of rubber and structurally enhancing material that may include embedded steel wire or mesh and synthetic cords or mesh in a strengthening belt that provides strength while maintaining resiliency. To insure adherence of the plies to each other during manufacture, the rubber must be at a specific temperature when joined to another layer. Additionally, the rubber, steel and synthetic material must adhere to each other, thus all material must be free of contaminants during the molding process.
If contaminants exist, or the curing process is compromised, the strengthening belt(s) will eventually separate from the rubber plies or individual plies of rubber will separate. This separation results in hot spots forming in the tire with eventual catastrophic failure of the tire. Inter-ply separation can result in complete destruction of the vehicle with loss of life. Thus, the ability to detect imminent tire failure may save lives and equipment.
This is particularly true in the case of airplane tires and automotive tires used at high speed. For example, excessive tire temperatures from tread separation and the like may result in catastrophic wheel well fires when aircraft tires are superheated and retracted into the aircraft. Of particular concern are truck tires used to carry heavy loads at higher inflation pressures than passenger car tires.
For heavy duty over-the-road trucks, tread separation can be problematic, especially when the truck involved is carrying hazardous materials. Many trucks use re-treaded or “recapped” tires, particularly on trailers, as an economy measure. Such tires are particularly prone to tread and ply separation.
Even if damage does not occur as a result of ply separation, the presence of shed truck treads, termed “gators,” on the roadways presents a hazard to other motorists. Moreover, sudden blowouts of truck tires in the vicinity of passenger vehicles can be hazardous to the passengers. Unfortunately, there are no practical, yet economical, self-contained systems available to monitor and alert to heat build-up within tires. Available systems are expensive, bulky, or both, and many provide only localized information on temperature changes. Conventional tire testing systems generally deal with looking for defects (occlusions and the like) within tires for production testing purposes or are directed toward external measurements of temperature, tire pressure, and stress. Examples are represented in the following patents.
U.S. Pat. No. 5,837,897, Apparatus for Testing the Traction Properties of Pneumatic Tires, to Jones et al., Nov. 17, 1998, incorporated herein by reference, discloses an external ultrasonic device for tire testing which may be used to determine tire pressure.
U.S. Pat. No. 5,067,347, Method and Apparatus for Testing a Pneumatic Tire, to Mönch, Nov. 26, 1991, describes a method for testing a tire by pre-heating the air needed to inflate the tire to reduce the test period.
U.S. Pat. No. 4,233,838, Load Control for Tire Test Machine, to Stiebel, Nov. 18, 1980, describes an external controller for varying the load on a tire under test, that during equilibrium testing, correlates a relatively fast increase in temperature with a corresponding fast load increase to indicate incipient failure of the tire.
U.S. Pat. No. 4,150,567, Method of Estimating Energy Loss from Pneumatic Tires, to Prevorsek et al., Apr. 24, 1979, provides an equation for quantifying tire performance of two similar tires differing in only one characteristic by externally collecting selected temperature and heat generation rates, and determining dynamic tensile moduli from selected sections of the tires under varying conditions.
In addition to systems and methods for tire testing, there are patents for onboard systems, samples of which follow.
U.S. Pat. No. 3,852,717, Device for Automatically Detecting Abnormal Conditions in Vehicle Tires, to Hosaka et al., Dec. 3, 1974, provides a pressure switch and a thermistor mounted within a wheel assembly that are connected in series to a coupling unit, the primary coil of which is secured on the journal of the axle and the secondary coil of which is mounted concentrically on the vehicle's axle. A warning signal is sent to the driver when a threshold is exceeded.
U.S. Pat. No. 3,760,351, Apparatus and Process for Developing Electromagnetic Energy from Tire Flexure, to Thomas, Sep. 18, 1973, mounts within the tire one or more actuators that are reciprocated radially once each rotation of the tire by the normal distortion of the tire upon rotation. This action operates a generator, the energy derived therefrom usable for operating a separate device or for signaling tire operating parameters.
U.S. Pat. No. 3,662,335, Device for Road Vehicle for the Wireless Transmission of at Least One Measured Value of a Rotating Wheel to an Indicating Instrument, to Fritze, May 9, 1972, incorporated herein by reference, describes a wireless device for monitoring the performance of a tire while in operation. The internal wheel or internal tire bead-mounted coupling element, an oscillator-antenna with a resonant circuit, and a switch, extend coaxially to the vehicle hub, the elements themselves extending radially outside of the base of the wheel rim about the entire circumference of the wheel, being accommodated within or internally on the tire casing near an outer edge of the tire rim. The transmitter and associated antenna is mounted on the frame of the vehicle near the wheel for picking up the reflected signal from the wheel, with all signal processing electronics located on the vehicle and powered thereby.
More recently, designers have capitalized on the reduced size and expense of solid state electronics to effect an onboard solution, as evidenced in the following patents.
U.S. Pat. No. 6,232,875 B1, Apparatus and Method for Controlling a Tire Condition Module of a Vehicle Tire, to DeZorzi, May 15, 2001, describes onboard, i.e., internal to a tire/wheel assembly, multi-mode internally powered tire condition sensor/transmitter modules that include a motion sensor; an application specific integrated circuit (ASIC) that contains appropriate sensors, such as temperature and pressure sensors, and serves as the module's mode controller and signal processor; and an antenna providing output to effect a wireless link to a receiver module onboard the vehicle. Signals from the modules are received by the receiver module that contains appropriate circuitry for decoding the received signals and may contain an integrated controller for further processing and providing both a monitor status and an alert. The system specifically provides a “sleep” mode to conserve energy when the vehicle is stopped.
U.S. Pat. Nos. 6,175,302 B1, 5,889,464, and 5,781,104, each entitled Tire Pressure Indicator Including Pressure Gauges That Have a Self-Generating Power Capability, all to Huang, Jan. 16, 2001, Mar. 30, 1999, and Jul. 14, 1998, respectively, provide a set of pressure (only) gauges, each one to be installed in a tire/wheel assembly of a vehicle. The gauges communicate with a receiver onboard the vehicle. Each pressure gauge contains an internal power supply, a sensor, and a transmitter. For the '302 patent, the power supplying device is a self-generating voltage supply formed by a piezoelectric element, a spring, and a weight. The spring vibrates during wheel rotation, causing the piezoelectric element to generate energy for powering the gauge. The sensor includes a capacitor having a moving member sensitive to internal pressure, thus providing an indication of relative pressure via changes in capacitance. For the '464 patent, the sensor includes a sensing coil, a volume variable member, a magnetic core and an encoder. For the '104 pat
Evans James A.
Mason George L.
Baugher Jr. Earl H.
Chapman John E.
The United States of America as represented by the Secretary of
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