Hydraulic cylinder piston position measuring system - uses propagation time of ultrasonic pulses reflected from end face of piston

摘要

The measuring system uses an ultrasonic transducer (48) inserted in the front face (24) of the cylinder (12) transmitting an ultrasonic pulse through the cylinder space (26) containing the hydraulic fluid towards the front face (28) of the piston (14). These pulses are reflected by the latter back to the transducer (48) with the overall propagation time of the pulses for the forward and return journey being measured to deduce the distance of the piston (14) from the front end (22) of the cylinder (12). Pref. the transducer (48) is coupled to a processor (46) controlling a valve block (36) coupled to the cylinder spaces (26,30) on both sides of the for maintaining the piston in the correct position. The system can be used for a hydraulic piston/cylinder positioning control for a machine part or machine tool.