| 摘要 |
<p>PURPOSE:To set a pump pressure according to the operation level of an operation lever, and to improve the driving operation sense and accommodation sense of a driver by guiding pilot pressure responding to the operation level of the operation lever to the pilot port of a direction switch valve through an electromagnetic pressure proportional valve. CONSTITUTION:When an operation lever 29 is tilted from a neutral position and operated, the operation signal is input to a controller 30, and a control signal based on the operation signal is determined thereby. Either one of right and left electromagnetic pressure proportional valves 23 and 24 provided on the pilot circuit of a direction switch valve 20 is selected by the control signal, and a pilot pressure adjustment command signal is output toward the selected electromagnetic pressure proportional valve 23 or 24, and the spool of the direction switch valve 20 is slid and displaced. When the operation lever 29 is in the neutral position, the amount of passing main pressure oil is calculated based on the pressure signals of pressure sensors 37, 38 for detecting the upstream and downstream pressure of the electromagnetic proportional valve 33 in a main pressure circuit, and a meter-in opening command is given to the electromagnetic proportional valve 33.</p> |
