| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase the maximum drive speed of a boom cylinder at the time of a boom elevating operation, cause the drop of the speed at the time of a boom lowering operation, and maintain the hydraulic fluid amount required for each actuator at the time of a combined operation for lowering the boom and crowding an arm, as well as a combined operation for crowding a bucket. SOLUTION: The function generator 151 of a controller computes the first target displacement volumeθn of a hydraulic pump on the basis of negative control pressure. Also, function generators 141 and 142, and a maximum value selection part 143 compute the first and the second limit valuesθandθv corresponding to an arm crowding operation variable as well as a bucket crowding operation variable, and output the larger value thereof as the third limit valueθav. Furthermore, a setting part 144, a tilt and rotation amount selector part 145, and a minimum value selection part 147 useθn as target displacement volumeθwhen a boom lowering operation is not detected, and control the maximum value ofθn so as not to exceedθav when the boom lowering operation is detected.</p> |
