| 摘要 |
PURPOSE:To prevent the hunting phenomenon of a rubber dam by controlling the vertical movement of water level by a method in which three set water levels for upper limiting, lower limiting and target are detected by electrode bars, and the inflow and outflow of fluid in a rubber dam are controlled by detection signals from the electrode bars. CONSTITUTION:When a water surface 6 exceeds an upper limiting water level 10, the water surface 6 comes into contact with an upper limiting water-level electrode bar 7, the detected signal of upper limiting water level is generated, and a discharge valve 5 is opened. A fluid is discharged out of a rubber dam 1, the height of the dam 1 is reduced, and the water level is decreased. When a target set water level 11 is reached, the electrode bar 8 is separated from the water surface 6, and the valve 5 is closed. When the water level 6 is further reduced and reaches a lower set limiting water level 12, it is detected by a lower limiting water level electrode bar 9, an inflow valve 2 is opened, the fluid is flowed into the dam 1 to raise the dam 1, and the water level 6 is raised. The rising speed of the rubber dam having a slightly steeper slope than the raising slope of the water level 6 is set up to control the vertical movement of the water levels. |
