| 摘要 |
PURPOSE:To reduce capacity of a hydraulic rotary machine while properly maintaining hydraulic pressure to a load at the time of unload operation of an unload valve by adopting a variable displacement type hydraulic rotary machine. CONSTITUTION:When a hydraulic rotary machine is rotated by an engine, if hydraulic pressure to a load is low, operating fluid in a reservoir tank 80 is sucked by the hydraulic rotary machine, which is discharged into the load as pressure fluid through a main diaphragm 110 as well as a check valve 120. When the hydraulic pressure in the downstream of the main diaphragm 110 is properly raised, the pressure fluid from the main diaphragm 110 is released to the reservoir tank 80 through an auxiliary diaphragm 130 by an unload valve 150 so as to turn the hydraulic rotary machine into an unloaded condition, while the open condition is maintained according to the hydraulic pressure in the downstream of the check valve 120. Since pressure difference between the hydraulic pressure in the upstream of the main diaphragm 110 and the hydraulic pressure in the downstream of the auxiliary diaphragm 130 is increased, the pressure fluid in the downstream of the check valve 120 is given thereto by the hydraulic rotary machine so as to reduce its capacity. |
