| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic driving device of a hydraulic excavator for efficiently performing horizontal leveling work, by using remaining energy of pressure oil in a hydraulic circuit of not paying attention in a conventional technology. <P>SOLUTION: This hydraulic driving device of the hydraulic excavator has a boom cylinder 1 and an arm cylinder 2, a main hydraulic pump 4 supplying the pressure oil to both cylinders 1 and 2, a directional control valve 7 for a boom and a directional control valve 8 for an arm for respectively controlling a flow of the pressure oil supplied to the boom cylinder 1 and the arm cylinder 2, and a tank oil passage 8c connecting the directional control valve 8 for the arm to a hydraulic fluid tank 6. A flow control valve 15 capable of selectively closing the tank oil passage 8c is provided. When rod side hydraulic pressure of the arm cylinder 2 increases to a preset value or more when performing the horizontal leveling work by composite operation of boom lifting and arm crowding, the outflow of rod side pressure oil of the arm cylinder 2 to the hydraulic fluid tank 8c, is checked by closing the tank oil passage 8c by the flow control valve 15, and the rod side pressure oil is supplied to the bottom side of the boom cylinder 1. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
