Hydraulic actuator.

摘要

An electro-hydraulic proportional actuator includes a piston and cylinder(10) which is positioned hydraulically by fluid flow through two solenoid valves (15, 16) operable by an electronic control system. An operator control (34) provides an input voltage (V1) representing a desired piston position and a transducer (35) generates a voltage (Vv) representing the actual piston position. The difference between the input and output voltages generates a difference or error signal (Ve2) that is fed into a feedback system including a sample-and-hold circuit (36). A clock logic system (39,42,46,54) is provided for transmitting the signal from the feedback system to the solenoid valve at predetermined intervals to activate either valve to move the actuator piston in either direction or to activate both valves to hold the piston at a desired position.