Distance measuring apparatus and a differential pressure transmitter utilizing the same

摘要

A distance measuring apparatus and a differential pressure transmitter utilizing the same having an ultrasonic element reflector mounted between a pair of ultrasonic transducers. The alternate operation of the ultrasonic transducers produces a pair of transducer energizing signals which are related to the relative separation of the reflector element from the transducers. In one embodiment, the reflector element is mounted within a closed pressure vessel divided internally by an ultrasonic reflector diaphragm with a pair of fluid inlet lines admitting respective pressurized fluids to corresponding sides of the reflector diaphragm. The ultrasonic transducer elements are mounted on the outside of the pressure vessel on an acoustical signal transmitting interface and are arranged to alternately supply an ultrasonic signal through the pressure vessel wall to the respective side of the diaphragm reflector while an analysis of the frequency of operation of each transducer is used to determine the differential pressure applied to the diaphragm.