| 摘要 |
PROBLEM TO BE SOLVED: To provide a closed circuit hydraulic system for a working vehicle dispensing with a displacement control valve by using an electric hydraulic displacement variable pump. SOLUTION: This closed circuit hydraulic system includes a fluid tank, a hydraulic cylinder having a cylinder rod, a bidirectional variable displacement hydraulic pump for pressing the fluid to elongate or contract the cylinder rod in accordance with necessity, a flow rate control valve for reducing oil pressure between the bidirectional variable displacement hydraulic pump and the hydraulic cylinder, and a low-pressure check valve between the variable displacement hydraulic pump and the fluid tank. An accumulator is further mounted for saving residual energy and the fluid from the hydraulic cylinder during the contraction of a charging pump for charging the variable displacement hydraulic pump and the expanded cylinder rod, and utilizing the fluid and energy during expanding the hydraulic cylinder to reduce the load to the charging pump. The flow rate control valve is opened in accordance with necessity to permit the floating. COPYRIGHT: (C)2005,JPO&NCIPI |
