Shock absorption device and control method thereof for small swing radius excavator

A method of controlling a shock absorption device for a small swing radius (SSR) excavator, including an engine, first and second hydraulic pumps, an engine speed setup means, a boom cylinder coupled to the first hydraulic pump, a main control valve for controlling hydraulic fluid being supplied to the boom cylinder, a control lever for outputting signal pressure corresponding to an amount of manipulation thereof, a flow controller for controlling the discharge flow rate of the first and second hydraulic pumps, a boom confluence means for making the hydraulic fluid discharged from the first and second hydraulic pumps confluent together, a boom-up manipulation amount detection means for detecting a boom-up signal pressure, a boom-up speed computation means for predicting a boom-up speed, a boom deceleration judgment means for judging whether the boom decelerates, and a deceleration flow computation means, the method comprising:

• detecting boom-up signal pressure in accordance with the manipulation mount of the control lever;
• predicting the boom-up speed in accordance with output signals of the engine speed setting means and the boom-up manipulation amount detection means;
• detecting a boom deceleration region in which a rotation angle of a boom exceeds a preset rotation angle and deceleration of the boom cylinder is required in a boom rotation region;
• calculating the discharge flow rate of the first and second hydraulic pumps so as to decelerate the boom cylinder, without applying shock to the excavator, if the rotation angle of the boom exceeds the preset rotation angle;
• limiting the discharge flow rate of the first and second hydraulic pumps so that an output value of the boom-up speed computation means does not exceed an output value of the deceleration flow computation means from a time point when an output signal is generated from the boom deceleration judgment means if the output signal is generated from the boom deceleration judgment means;
• and
• determining whether to make the hydraulic fluid of the second hydraulic pump confluent in accordance with the limited discharge flow rate of the first and second hydraulic fluid.