Patent ID: 8516805
Filing Date: 2013-08-27
Classification: B01D,E02F,F01N,F02D,F15B

Abstract:
1. A hydraulic drive system for a working machine, said hydraulic drive system being provided with plural hydraulic actuators for driving the working machine, a hydraulic pressure source for producing, by a hydraulic pump, pressure oil to be fed to the plural hydraulic actuators, control valves separately arranged for the plural hydraulic actuators, respectively, to control flows of pressure oil between the corresponding hydraulic actuators and the hydraulic pressure source, an engine as a drive source for the hydraulic pump, an exhaust gas purification device for capturing, by a filter, particulate matter in exhaust gas produced by the engine, a forced regeneration means for burning particulate matter deposited on the filter, and a control means for controlling the forced regeneration means, said forced regeneration means serving to raise a delivery pressure of the hydraulic pump to increase an engine output such that the exhaust gas is provided with heat needed to burn the particulate matter, wherein: valve positions of the control valves are set to change between initial positions, in which the flows of pressure oil from the hydraulic pressure source to the hydraulic actuators are cut off to guide the pressure oil to a hydraulic oil reservoir, and operating positions, in which the pressure oil from the hydraulic pressure source is guided to the corresponding hydraulic actuators; the forced regeneration means includes a specific one of the control valves as a means for raising the delivery pressure of the hydraulic pump; the hydraulic drive system is further provided with a forced regeneration command means for commanding conduct of forced regeneration when operated, and also with a non-operated state detecting means for detecting a non-operated state in which the valve positions of all the control valves are in states of the initial positions; and taking as a condition for the conduct of forced regeneration that a non-operated state has been detected by the non-operated state detecting means, the control means actuates the specific control valve to raise the delivery pressure of the hydraulic pump when the conduct of forced regeneration is commanded by the forced regeneration command means.