Piezoelectric reed power supply for use in abnormal tire condition warning systems

Abstract

A device is provided for sensing the condition of a pneumatic tire preferably of the type used on an automobile wherein the tire is mounted on a tire rim and the tire is subject to normal vibrations. The device comprises a housing, a band for mounting the housing to the tire rim, a sensor for monitoring the condition within the tire, circuitry operatively connected to the sensor for generating radio signals indicative of the tire condition, power supply operatively connected to the circuitry and a receiver for receiving the radio signals. The power supply includes a piezoelectric reed having a base portion and an end portion. The base portion is elastomerically bonded to the housing. A tuning mass member is mounted to the end portion and is configured for mating abutment against stop members which limit the flexure stroke of the piezoelectric reed and inhibit compound bending of the reed. The tuning mass member includes an outer weighted casing and an inner elastomeric portion insulating the reed from physical shocks to the outer casing and from electrical shorts across the casing. The tuning mass member is sized relative to the piezoelectric reed to obtain a resonant frequency of vibration of the power supply induced by common road vibrations during wheel operation. The reed is symmetrically configured about a radiating center line of the tire.

Dependencies are inferred from the claim text.