Patent ID: 8016087
Filing Date: 2011-09-13
Classification: F16F

Abstract:
1. A fluid damper comprising: a fluid having magnetic properties, a piston formed of a magnetic material; a cylinder which encapsulates the fluid having magnetic properties and accommodates the piston; a piston rod which pierces an end face member of the cylinder in an axial direction to support the piston; a magnetic field generation device provided outside the cylinder; a first yoke which is arranged around the cylinder and magnetically connects the piston with the magnetic field generation device; and a second yoke which is arranged around the piston rod outside the cylinder and magnetically connects the piston rod with the magnetic field generation device, wherein the piston rod has: a magnetic portion which forms a first magnetic circuit together with the piston, the first yoke, the magnetic field generation device, and the second yoke when the piston is displaced to one side in the axial direction beyond a neutral region; a magnetic portion which forms a second magnetic circuit together with the piston, the first yoke, the magnetic field generation device, and the second yoke when the piston is displaced to the other side in the axial direction beyond the neutral region; and a non-magnetic portion which cuts off the first magnetic circuit and the second magnetic circuit when the piston is in the neutral region, and a magnetic flux density of each magnetic circuit passing through a gap between an outer peripheral surface of the piston and an inner peripheral surface of the cylinder varies in accordance with movement of the piston in the axial direction.