| 摘要 |
PURPOSE:To prevent the pulsation of pressure by a simple hydraulic circuit by a method wherein pre-compression switching valves and pre-reduction switching valves, provided at the sides of upper and lower dead points of a plurality of hydraulic pistons, are connected to hydraulic cylinders. CONSTITUTION:The hydraulic piston 3a is in stopping state at the dead point thereof while the hydraulic piston 3b is pushing out slurry in the hydraulic cylinder 1b into a discharging line 12. A piston rod 5b opens the precompression switching valve 8b before the hydraulic piston 3b arrives at the lower dead point, a high pressure in the hydraulic cylinder 1b is supplied into the hydraulic cylinder 1a through a non-return valve 14e as well as the precompression switching valve 8b and the pressure in he hydraulic cylinder 1a is switched into a high pressure during stopping of the hydraulic piston 3a. When the hydraulic piston 3b arrives at the lower dead point, a speed detector 6b detects the position of the lower dead point of the piston 3b, a solenoid valve 7d is conducted and the piston 3a begins to move toward the lower dead point. The inside of the hydraulic cylinder 1a is in the condition of high pressure, therefore, the pulsation of pressure upon starting of the motion of the piston 3a will never be generated. |
