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Hydraulic circuit and control system therefor

  • US 5,138,838 A
  • Filed: 02/15/1991
  • Issued: 08/18/1992
  • Est. Priority Date: 02/15/1991
  • Status: Expired due to Term
First Claim
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1. A control system for a hydraulic circuit having a tank, a pump connected to the tank, a supply conduit connected to the pump, a reversible hydraulic motor, and a pair of motor conduits connected to the motor, comprising:

  • first and second independently operable electrohydraulic control valves with each being disposed between an associated one of the motor conduits and the supply conduit and the tank, each of the control valves having a neutral position at which the associated motor conduit is blocked from the supply conduit and the tank and being movable in a first direction in response to receiving a first control signal for establishing communication between the associated motor conduit and the supply conduit and in a second direction in response to receiving a second control signal for establishing communication between the associated motor conduit and the tank, the extent of movement in either direction being dependent upon the magnitude of the control signal received thereby;

    pressure sensing means connected to the conduits for outputting a plurality of discrete pressure signals to the control means corresponding to the fluid pressures in the conduits;

    means for outputting a command signal to establish a desired fluid flow rate and direction of fluid flow through both of the control valves; and

    control means for processing the command signal, for producing the first and second control signals in response to the command signal, and for outputting the first control signal to one of the control valves and the second control signal to the other of the control valves, said control means being operative for processing the pressure signals and modifying the first control signal to maintain the desired flow rate through the control valve receiving the first control signal regardless of the pressure differential thereacross.

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