| 摘要 |
PROBLEM TO BE SOLVED: To conduct arm operation without trouble during boom-down operation under low load. SOLUTION: The drive control device of a hydraulic cylinder includes hydraulic pumps 21, 22, a boom cylinder 11 and an arm cylinder 12 driven by hydraulic oil from the hydraulic pumps 21, 22, operation means 27, 28 for generating driving commands of cylinders 11, 12, control valves 23 to 26 for controlling flow of the hydraulic oil from the hydraulic pumps 21, 22 to the cylinders 11, 12 according to the driving command of the operation means 27, 28, a valve means 30 for adjusting area of flow passages from the hydraulic pumps 21, 22 to a rod chamber 11a of the boom cylinder 11, operation detection means 41, 42 for detecting operation of the operation means 27, 28, a pressure detection means 47 for detecting pressure of a bottom chamber 11b of the hydraulic cylinder 11, a judgement means 40 for judging as achievement of high load condition when a value not less than a predetermined value is detected by the operation detection means 41, 42 and pressure not more than the predetermined value is detected by the pressure detection means 47, and a controlling means 40 for controlling the valve means 30, when the high load condition is judged as successfully achieved by the judgement means 40, so that the area of the flow passage increases more than that when it is judged that the high load condition is not successfully achieved. COPYRIGHT: (C)2005,JPO&NCIPI
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