Measuring and testing – Tire – tread or roadway – Tire inflation testing installation
Reexamination Certificate
2001-01-17
2002-10-15
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Tire, tread or roadway
Tire inflation testing installation
C073S146000, C073S146500, C073S146800, C340S447000, C340S442000
Reexamination Certificate
active
06463798
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to tire inflation pressure monitoring, and more particularly, to wireless tire inflation pressure monitoring, tire location determination, and related secure data transfer.
BACKGROUND OF THE INVENTION
Tire inflation pressure monitoring is becoming more prevalent in all types of vehicles, such as cars, trucks, sport utility vehicles (SUVs), off-road vehicles, airplanes, motorcycles, bicycles, mobile industrial and construction equipment, and the like. Vehicle operation, safety and mileage, for example, depend on proper tire inflation pressures. When a puncture, slow leak or other low pressure condition occurs, it is advantageous to alert the vehicle operator. In addition, the newer “no flat” tires typically require attention within a certain mileage range when they lose pressure because of a puncture or other malfunction.
Tire pressure monitoring for a vehicle has been implemented in one system with a small low power transmitter and pressure sensor located on each tire. Each tire pressure sensor-transmitter sends its respective tire pressure to a receiver that supplies the tire pressure values and any alarms thereof to a tire inflation pressure monitor having a display. The tire inflation pressure monitor and display may be part of a driver information display located in the dashboard, a console or the sun visor area of the vehicle.
The tire pressure sensor-transmitter is a low power, radio frequency device having a self-contained battery with sufficient life for the system to be of practical use. The device is small enough to fit inside a tire or to be incorporated in a valve stem. The tire pressure sensor-transmitter periodically sends pressure information to the receiver of the tire inflation pressure monitor and display. Each of the tires on the vehicle, including the spare tire(s), has a tire pressure sensor-transmitter with a unique code or other identifier. This identifier is used to associate an inflation pressure reading with a particular tire in a known location. Therefore, the tire inflation pressure monitor and display inside of the vehicle when calibrated or programmed indicates to the driver the location of the tire having an inflation pressure problem.
A problem exists in such systems, however, when tires are rotated or replaced. In those cases, the locations of the uniquely coded tire inflation pressure sensor-transmitters change. Manual recalibration or reprogramming of the tire inflation pressure monitor and display is necessary if correct tire location indication is desired with the pressure indication and/or alarm functions. Thus, there remains a need for a reliable, simple and automatic way of determining the actual location on a vehicle of a tire inflation pressure sensor-transmitter, and for systems providing such determined locations with pressure indication and/or alarm functions.
SUMMARY OF THE INVENTION
The invention overcomes the above-identified problems, as well as other shortcomings and deficiencies of existing technologies, by providing in one aspect a method and apparatus for monitoring the inflation pressure of each tire on a vehicle and determining the associated wheel location thereof. Advantageously, embodiments of the invention do not require a physical or hardwired electrical connection to each tire from a receiver for the determination of inflation pressure and wheel location thereof. In one embodiment, a wireless tire inflation pressure measuring device is attached to or is a part of each vehicle tire and is adapted for measuring the inflation pressure. A tire inflation pressure monitor receives the inflation pressure information from each of the wireless tire pressure measuring devices by radio frequency transmission or electromagnetic coupling. The tire inflation pressure monitor may indicate each tire inflation pressure being monitored and also may be adapted to produce an alarm indication, e.g., when a tire inflation pressure is below a certain pressure value, outside an acceptable range, falling, etc. The location of the tire having the inflation pressure alarm also may be indicated. A tire inflation pressure monitor adapted to provide such indication may be located, by way of example, in the visor area of the vehicle, attached to a sun visor or built into a console of the vehicle. Alternatively, the tire inflation pressure monitor may be attached to or built into the dashboard of the vehicle, or the pressure can be announced by voice, projected onto a surface such as a windshield, displayed by video monitor, etc.
In an embodiment of the present invention, a wireless tire inflation pressure measuring device may be built into the air valve stem or adapted to attach to a tire's existing air valve stem. It is contemplated and not outside the scope of the invention that the wireless tire pressure measuring device may also be built into or be disposed proximate to the tire, wheel (for convenience, wheel and wheel rim are used interchangeably herein), and/or valve stem. The wireless tire inflation pressure measuring device may comprise a pressure sensor having a pressure signal output, an electronic circuit for converting a pressure signal (e.g., from the pressure sensor) to an electronic pressure information signal, a low power radio frequency transmitter adapted to transmit the electronic information signal on a radio frequency signal, an antenna coupled to the low power radio frequency transmitter and adapted to radiate the radio frequency signal, and a battery operably coupled to power the low power radio frequency transmitter and electronic circuit.
The pressure sensor may be any type of pressure sensor which converts a pressure input to an electronic pressure signal output. The electronic circuit may comprise an analog or digital encoder/modulator that is adapted to modulate the low power radio frequency transmitter with information representing, reflecting, or corresponding to the electronic pressure information signal and, in some of the embodiments, an identifier. The identifier may be used to associate a tire with inflation pressure information. In one embodiment, the identifier may be a tone or other subcarrier being modulated by the electronic pressure information signal (e.g., in the case of analog modulation). In another embodiment, (e.g., for digital modulation) the identifier advantageously is a digital code which is part of a digital modulation code word containing both the identifier and a digital representation of the electronic pressure information signal.
Low power radio frequency transmitters, one for each tire, may be adapted to transmit via an antenna a radio frequency carrier signal containing the identifier and electronic pressure information signal to a radio frequency receiver that may be part of a tire inflation pressure monitor located inside of the vehicle. The antenna advantageously is oriented at the tire such that the signal strength of the transmitted radio frequency signal at the radio frequency receiver varies as the tire rotates. Thus, the rotation of the tire (resulting in changing antenna orientation) amplitude modulates the carrier of the transmitted radio frequency signal at the rotational rate of the tire. One rotation of the tire will produce one amplitude variation cycle of the radio frequency carrier. This amplitude variation (modulation) may be detected so as to determine the rotational speed of each tire.
When a vehicle makes a turn, the tires on the outer radius of the turn rotate faster than the tires on the inner radius of the turn. Further, the rear tires take short cuts relative to the front tires, thereby traveling in the same time a shorter distance than do the front tires. Thus, the rear tire rotates at a slower speed relative to the front tire on each side of the vehicle.
Since the rotational speed of each tire may be determined as disclosed herein, and the direction of the turn also may be known, it may be determined which of the front and rear tires are on the left side and on the right side of the vehicle.
Further, whe
Katz Paul N.
Niekerk Jan Van
St. Amand Roger
Uradnik Joseph A.
Allen Andre
Baker & Botts L.L.P.
Microchip Technology Incorporated
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