| 摘要 |
PURPOSE:To reduce the energy loss and in particular suppress the energy loss in idling by installing the bypass passage of a differential pressure generating valve, throttle installed in the bypass passage, and a flow rate control valve for restricting the throttle flow rate to a constant value. CONSTITUTION:Though a portion of the discharge flow rate of a constant capacity type hydraulic pump 6 flows into a passage 82 which makes a detour around a differential pressure generating valve 81, the bypass flow rate is limited or a certain value by a flow rate control valve 83, and also the differential pressure due to a throttle 84 on a bypass passage side is restricted to a constant value. Within the range of the restricted bypass flow rate, nearly all the discharge flow rate of the constant capacity type hydraulic pump 6 flows into the bypass passage 82. Accordingly, the useless pressure loss in the region having the number of idle revolution or less can be reduced. Further, in comparison with the case where the bypass passage 82 is not formed, the differential pressure generated in all the revolution speed region can be reduced evenly, and the energy loss can be reduced. |
