Patent ID: 7162945

Claim:
A torsional rigidity control device comprising: a moment variable means for regulating a fluid pressure supplied from a fluid pressure source by calculating a necessary fluid pressure value and comparing said necessary fluid pressure value to an actual value of fluid pressure supplied to a rotary actuator or a cylinder, said fluid pressure controlling a moment loaded on a stabilizer based on the comparison of said necessary fluid pressure value and said actual value to counteract an external moment applied to the stabilizer, said fluid pressure source driving a rotary actuator connected to an intermediate part or one end of the stabilizer, or driving said cylinder connected to one end of the stabilizer; a supply flow path connected to said fluid pressure source; a discharge flow path connected to a reservoir; two supply/discharge flow paths connected respectively to two pressure chambers formed in said rotary actuator or said cylinder; a pressure control valve connected to said supply flow path and said discharge flow path; a direction switching valve for connecting said supply flow path and said discharge flow path to one of said two supply/discharge flow paths selectively; and a check valve permitting only a fluid flow from said supply flow path side to said discharge flow path side and a relief valve disposed between the supply flow path and the discharge flow path and in parallel with said pressure control valve.