Gould Inc.

National Semiconductor Corporation

David A Betts

Lyle A Pauer

Gregory W Ledenbach

Donald J Karbo

An abnormal tire profile indicating system comprising a telemetry unit mounted on each wheel of a vehicle and a central receiver. Each telemetry unit comprises a piezoelectric transducer which is deflected with each wheel revolution when the tire profile is low. Deflecting the transducer produces an electric pulse. The transducer pulses are accumulated on a charge storage capacitor to provide a power supply. When the level of charge on the capacitor reaches a predetermined level, a counter commences counting the transducer pulses. When a predetermined number of pulses are counted, the counter renders a transistor conductive, which transistor connects the power supply capacitor to an encoder and a transmitter. The encoder produces encoded signals and resets the counter after a predetermined number of encoder signals are produced. The central receiver receives the modulated radio signals from each of the telemetry units. The counter limits the transmitter to transmitting only after a sufficient number of low profiles are detected to assure reliable operation and only after a sufficient number of wheel revolutions to meet FCC periodicity of transmission requirements. The reset counter limits the duration of transmissions to meet FCC requirements.

Low tire warning system

An abnormal tire profile indicating system comprising a telemetry unit mounted on each wheel of a vehicle and a central receiver. Each telemetry unit comprises a piezoelectric transducer which is deflected with each wheel revolution when the tire profile is low. Deflecting the transducer produces an electric pulse. The transducer pulses are accumulated on a charge storage capacitor until a threshold level is reached. A threshold level detector causes a transistor connected to the capacitor to become conductive when the threshold level is exceeded. This transistor, when conductive, powers a counter, an encoder and a transmitter. The counter counts the number of times the transistor become conductive and produces an enable signal when a predetermined number is counted. The enable signal enables the transmitter to receive an encoded signal from the encoder and modulates a radio carrier frequency with the encoder signal. The modulated radio signals are received from each telemetry unit by the central receiver. The central receiver produces an indicia of the occurrence of the abnormal tire profile at one or more of the wheels. The counter limits the transmitter to transmitting only after a sufficient number of detections to assure that the sensed conditions are due to a low profile rather than rough roads or extraneous signals. Further, the counter allows radio transmissions only after a sufficient number of wheel revolutions to meet FCC requirements on the periodicity of transmissions.

A self powered tire condition indicator system is disclosed. The system comprises a plurality of wheel mounted transmitting assemblies which communicate by a radio frequency transmission to a receiver located within the operator compartment of a vehicle. Each of the transmitting assemblies generates its own transmitting power by converting the mechanical compression of a flat tire into electrical energy. The electrical energy is used to generate an intermittent characteristic tone associated with a deflated tire condition by the frequency modulation of a carrier.

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Mentor-on-the-Lake, OH, United States of America

David A Betts