Patent ID: 8794401

Claim:
A fluid shock absorber comprising: a cylinder; a cylinder-inserted body inserted into the cylinder and performing a relative displacement in an axial direction at a relative displacement speed with respect to the cylinder; a damping force generating mechanism that generates a fluid damping force against the relative displacement of the cylinder-inserted body with respect to the cylinder in the axial direction; a seal member including a ring-shaped sliding surface and interposed between the cylinder and the cylinder-inserted body; and a frictional resistance regulating mechanism provided in the cylinder, the frictional resistance regulating mechanism regulating a frictional resistance between the seal member and the cylinder-inserted body, so that when the relative displacement speed is increasing but is less than a predetermined speed greater than zero, the frictional resistance stays the same, and when the relative displacement speed is increasing and equal to or greater than the predetermined speed, the frictional resistance decreases, the frictional resistance regulating mechanism including an actuator having a ring-shape which exerts a radial force on the seal member and is configured to change the frictional resistance by changing a diameter of the actuator, and a generator that generates a direct-current power in every instance that relative displacement occurs between the cylinder-inserted body and the cylinder in the axial direction and impresses the direct-current power directly on the actuator, wherein the generator is configured to increase a voltage of the direct-current power as the relative displacement speed between the cylinder-inserted body and the cylinder in the axial direction increases, all of the direct-current power generated by the generator being directly applied to the actuator, wherein the direct-current power is directly impressed on the actuator so that no controller regulates the direct-current power applied to the actuator, the actuator is constituted by a polymer actuator which deforms upon impression of the direct-current power to the polymer actuator and is configured to enlarge in diameter as the direct-current power impressed on the polymer actuator increases, the seal member comprises an oil lip that is disposed on a radially inner side of the actuator and is supported by the cylinder so as to be in contact elastically with the cylinder-inserted body, and the actuator and the generator are provided separately.