Patent ID: 6382076
Filing Date: 2002-05-07
Classification: F15B

Abstract:
A piston main servo-actuation system comprising:a piston; a position transducer mechanically connected to the piston for producing a piston position signal; two feedback position control loops each receiving as input the piston position signal and piston position demands and producing an electrical demand output signal; two servovalves, identical in design and having a torque motor, the servovavles positioning the piston in response to the electrical demand output signal received from the respective control loops, the servovavles being fed by a high pressure supply line and a low pressure return line, each servovalve having an output control line connected to opposite sides of the piston and creating a hydraulic bridge configuration formed by (i) the high pressure supply line, the low pressure return line and the control line of one servovalve controlled by a first set of restrictions, and (ii) the high pressure supply line, the low pressure return line and the control line of the other servovalve controlled by a second set of restrictions; and two pressure select valves each being balanced at one end by a spring load and pressure from a reference line and at an opposite end by a working line, the pressure select valves being set with pressure from the supply line and return line through a third set of restrictions.