US Patent 11286647 Electrohydraulic control device for construction machine and method thereof

An electro-hydraulic control apparatus for construction machinery includes a control valve installed in a hydraulic line between a hydraulic pump and an actuator to control operations of the actuator according to a displacement amount of a spool therein, a spool displacement adjusting valve configured to output a secondary pressure in proportion to an inputted pressure command signal to the spool of the control valve to control the displacement amount of the spool of the control valve, a pressure sensor to detect the secondary pressure outputted from the spool displacement adjusting valve, and a controller configured to output the pressure command signal to the spool displacement adjusting valve according to a manipulation signal of the construction machinery, and to correct the pressure command signal when a pressure difference between the detected secondary pressure and a design pressure predetermined by the pressure command signal is out of a preset allowable range.