Patent attributes
A hydraulic drive system of a construction machine includes: a boom control valve connected to a boom cylinder by a boom raising supply line and a boom lowering supply line; a pump that sucks hydraulic oil through a suction line, and delivers the hydraulic oil through a delivery line; a regenerative valve that brings the boom raising supply line and the suction line into communication with each other through a regenerative line when a boom lowering operation is performed; and a controller that controls an accumulator switching valve. The controller: switches the accumulator switching valve to a pressure accumulation position when a pressure accumulation condition is satisfied; switches the accumulator switching valve to a pressure release position when a pressure release condition is satisfied; and switches the accumulator switching valve to a neutral position when neither the pressure accumulation condition nor the pressure release condition is satisfied.
