| 摘要 |
PURPOSE:To facilitate the control of a speed and to enable accurate stoppage at an arbitrary position, by forming a piercing passage to a pig main body and appropriately operating the valve plate mounted to the rear part of the pig main body. CONSTITUTION:This apparatus is constituted of a pig main body 1 movable in a pipe body, a piercing passage 2 communicating the front and rear of the pig main body 1, a valve plate 4 opening and closing the passage 2 and a drive means operating the valve plate 4. At first, when the main body 1 is allowed to advance and move in the piping, an actuator 6 is operated to closely contact the plate 4 with the rear end surface of the main body 1 to close the rear end opening 2a of the passage 2. Therefore, the main body 1 is pushed forwardly by the pressure of a fluid applied to the rear part of the main body 1 to advance. Next, when the main body 1 is stopped, the actuator 6 is released to rearwardly push the plate 4 by a compression spring 7 and the rear end opening 2a of the passage 2 is opened. When the passage 2 is opened, the pressurized fluid applied to the rear side of the main body 1 passes through the passage 2 to flow out to the front side of the main body 1 and the fluid pressure in the rear side of the main body 1 falls and pressing force is lost to stop the main body 1. |
