METHOD FOR CONTROLLING VARIABLE DISPLACEMENT PUMP

摘要

A method for controlling a variable displacement pump by calculation by a controller using a closed-center-type directional control valve, the method allowing effective utilization of the variable displacement pump while avoiding the risk of engine stall is provided. [Means for Resolution] The method includes the steps of: determining a first virtual discharge pressure from the real discharge flow rate of the variable displacement pump based on a characteristic curve defining the relation between discharge pressure and discharge flow rate of the variable displacement pump; determining a virtual bleed-off flow rate based on a virtual bleed-off area of the closed-center-type directional control valves determined according to the operation amount of the directional control valves, and determining a second virtual discharge pressure of the variable displacement pump based on a value obtained by subtracting the actuator flow rate and the virtual bleed-off flow rate from the virtual discharge flow rate of the variable displacement pump; and controlling the variable displacement pump based on a smaller value of the first virtual discharge pressure and the second virtual discharge pressure.