| 摘要 |
PROBLEM TO BE SOLVED: To provide lock and return functions in addition to a damping function by installing an opening and closing valve in an oil passage communicating oil chambers in front and in rear of a piston, and a main opening and closing valve in a main oil passage for supplying and discharging oil pressure to the oil chambers. SOLUTION: With an opening and closing valve for an oil passage 6 of a piston 2 fully opened, and main opening and closing valves 12 of main oil passages 10, 11 totally closed, the damping force of a base isolation layer at the time of an earthquake or a gale is increased by damping action caused by throttle action of the oil path 6. With the opening and closing valve totally closed, and the main opening and closing valve fully opened, the driving force of a product of oil pressure supplied to the oil chamber 4 or 5 and the pressure receiving area of the piston 2 is generated in a piston rod 17, thereby forcibly restoring a structure which causes residual deformation. With both vales totally closed, the piston 2 and the rod 17 are firmly fixed by incompressibility of oil closed in the oil chambers 4, 5 to exhibit fail-safe function of preventing vibration of a base isolation layer or preventing damage of the base isolation device due to repetition of vibration, thereby locking not to cause deformation in the base isolation layer. Thus, the respective functions can be used properly so as to simplify equipment and reduce the cose. |
