| 摘要 |
<p>A hydraulic drive system in a construction machine, comprising: a variable capacity type hydraulic pump (1); a hydraulic actuator (6) driven by pressure oil discharged from this hydraulic pump; flow rate control means (2; 8, 10) for controlling a flow rate of pressure oil fed to this actuator; and pump control means (2, 40, 42) for controlling the discharge flow rate of the hydraulic pump in such a manner that a pump discharge flow rate is decreased with the increase of the load on the actuator and a pump discharge flow rate is increased with the decrease of the load; wherein, for the purpose of preventing a sharp increase in the velocity of the actuator due to a sharp decrease in load which is not expected to occur during the normal operation, the said drive system further comprises a first detecting means (24) for detecting the magnitude of a load applied to the actuator (6), and a flow rate restricting means (43) for monitoring an abrupt decrease in the load on the actuator in response to a signal from the first detecting means and for controlling the flow rate control means (2; 8, 10) in such a manner that the increase in velocity of the flow rate of the pressure oil fed to the actuator is restricted when it is concluded that the actuator has reached a given state indicating an abrupt decrease in the load.</p> |
