Patent ID: 7252030
Filing Date: 2007-08-07
Classification: F15B

Abstract:
1. A hydraulic control circuit for driving an actuator by controlling a pressurized fluid from a hydraulic pump, the hydraulic control circuit comprising: a control lever for generating a manipulated signal according to a manipulated variable; a control valve installed on a supply line connecting the hydraulic pump and the actuator and driven by a pilot signal pressure for controlling a flow of the pressurized fluid traveling from the hydraulic pump to the actuator; a displacement sensor installed on an end of the control valve for detecting a switching position of the control valve; a pump pressure sensor installed on the supply line for detecting a pump pressure applied to the hydraulic pump; at least one electronic proportional valve driven by an external control signal for supplying a pilot signal pressure to the control valve; and a controller for receiving the manipulated signal from the control lever to determine a pilot signal pressure to be supplied to the control valve, outputting a corresponding control signal to the electronic proportional valve(s), receiving signals from the displacement sensor and the pump pressure sensor and comparing the signals with pre-stored reference data, and outputting to the electronic proportional valve(s) a stroke error correcting control signal for adjusting the switching position of the control valve wherein if an error is found in both switching position of the control valve and the pump pressure compared with the reference data of a present pilot signal pressure, the controller outputs to the electronic proportional valve(s) the stroke error correcting control signal for adjusting the switching position of the control valve.