Method for controlling flow rate of hydraulic pump of construction machine

A method for controlling discharge flow rate of hydraulic pump for construction machine, including a variable displacement hydraulic pump;

• a swing motor that is driven by working oil of the hydraulic pump to revolving an upper swing structure;
• a swing operation lever;
• a detection means for detecting an operation amount of the swing operation lever;
• an electric proportional valve for controlling the working oil supplied to the swing motor from the hydraulic pump;
• a pressure sensor for detecting a swing pressure generated in the swing motor;
• and a controller to which the detected signals are inputted from the detection means and the pressure sensor, the method comprising;
• detecting the operation amount of the swing operation lever and the swing pressure generated in the swing motor;
• calculating a flow rate required for the swing motor in response to the operation amount of the swing operation lever;
• calculating a first gradient value of swing acceleration to increase a discharge flow rate of the hydraulic pump from swing start, when the upper swing structure is to be revolved;
• correcting the first gradient value to a second gradient value by taking into account a difference between the swing pressure and a preset relief pressure of a relief valve as a reference pressure;
• and
• controlling the discharge flow rate of the hydraulic pump so that increase of the required flow rate is restricted to a flow rate corresponding to the second gradient value.