| 摘要 |
PURPOSE:To control securely lift of the poppet from outside by controlling the position of poppet, which is always maintained open due to the fluid pressure at the pump side, by means of the pilot pressure only; a command pressure from outside; independently of the pump side pressure. CONSTITUTION:When both the pilot pressure Pi and the liquid pressure of pump are zero, a stepped piston 7 is positioned uppermost due to a spring 17, and a poppet 3 is touched to a valve seat 4 by its dead weight, desconnecting a primary side path 13 from a secondary side path 18. When the pump working liquid is introduced into the primary side path 13, the poppet 3 is lifted by this liquid pressure to the maximum lift; that is, until the poppet 3 comes against the lower end of the stepped piston 7; thus, connecting the primary side path 13 to the secondary side path 18. Next, the pilot pressure Pi is introduced into a rod chamber 14 of the small diameter portion of the cylinder 9, then, the stepped piston 7 is pushed down until the push-down force balances with the spring force 17, so that the lift of the poppet 3 is reduced accordingly with attendant reduction in the area of opening. |
