| 摘要 |
PROBLEM TO BE SOLVED: To maintain linear characteristics between a current value for flow rate control and a flow rate of pressure oil irrespective of hydraulic pressure supplied to a positive pressure chamber so as to improve controllability.SOLUTION: A hydraulic control valve is structured such that a positive pressure chamber 8 for pressurizing a piston 7 in a valve opening direction and a back pressure chamber 9 for pressurizing the piston 7 in a valve closing direction are formed on both sides across the piston 7, an elastic member 15 for pressurizing the piston 7 in the valve closing direction is provided, the positive pressure chamber 8 is connected to the back pressure chamber 9 via a connection passage 16, further, a pilot valve 20 is connected to the back pressure chamber 9, and an aperture area of a port enlarges according to movement of the piston 7 and a valve element 14 in the valve closing direction to increase a flow rate. It includes variable valve mechanisms 16 and 17 for increasing an amount of pressure oil flowing from the positive pressure chamber 8 to the back pressure chamber 9 according to the movement of the piston 7 and the valve element 14 in the valve opening direction, or reducing the amount of the pressure oil flowing out from the back pressure chamber 9 to increase the hydraulic pressure in the back pressure chamber 9. |
