| 摘要 |
During a swing start, a pump torque calculating section associated with pump delivery pressure 43, a pump torque calculating section associated with swing operation pressure 44, and a maximum value selecting section 45 of a controller 38 performs control to change a maximum absorption torque of a second hydraulic pump 3 between Tb and Tc in accordance with a delivery pressure of the second hydraulic pump 3. In a combined swing operation combining swing with other motion, a subtraction section 47 performs a calculation to subtract a maximum absorption torque Tp2 of the second hydraulic pump 3 from a total pump torque Tr0 and control to thereby distribute an amount of torque reduced in the second hydraulic pump 3 to a first hydraulic pump 2 associated with an actuator other than a swing motor 7. An energy loss due to relief during the swing start can thereby be reduced to improve energy efficiency. Further, a required flow rate can be supplied to the swing motor during a process of transiting to a constant speed following the swing start, thus achieving a smooth shift to a constant speed swing. Improved combined work operability and work efficiency can therefore be achieved. |
