Motors: expansible chamber type – Working member position feedback to motive fluid control – Electrical input and feedback signal means
Patent
1987-02-26
1988-07-19
Garrett, Robert E.
Motors: expansible chamber type
Working member position feedback to motive fluid control
Electrical input and feedback signal means
342 61, 324 585B, 92 5R, F15B 1316, G01R 2704, F01B 2526
Patent
active
047577452
ABSTRACT:
An electrohydraulic servo system which includes an actuator having a cylinder and a piston variably positioned therewithin, a servo valve responsive to valve control signals for coupling the actuator to a source of hydraulic fluid, and control electronics responsive to piston position for generating the valve control signals. A variable frequency rf generator is coupled through associated directional couplers to a pair of antennas which are positioned within the actuator cylinder and physically spaced from each other in the direction of piston motion by an odd multiple of quarter-wavelengths at a nominal generator output frequency. A phase detector receives the reflected signal outputs from the directional couplers, and provides an output through an integrator to the frequency control output of the generator to automatically compensate frequency of the rf energy radiated into the cylinder and thereby maintain electrical quarter-wavelength spacing between the antennas against variations in dielectric properties of the hydraulic fluid due to changes in fluid temperature, etc. A second phase detector is coupled to the generator and one antenna to generate a piston position signal.
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Garrett Robert E.
Kapsalas George
Vickers Incorporated
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