Patent ID: 8539919

Claim:
A fluid brake device comprising: a case defining a fluid chamber inside; magnetic viscosity fluid kept in the fluid chamber, the magnetic viscosity fluid having a viscosity variable in accordance with magnetic flux passing through; a control device which carries out variable control of the viscosity of the magnetic viscosity fluid by varying the magnetic flux; a rotor having a brake shaft penetrating the case to come into contact with the magnetic viscosity fluid so that the rotor receives a braking torque according to the viscosity of the magnetic viscosity fluid; and a sealing sleeve arranged in the case to surround the brake shaft along a rotation direction, a seal gap being defined between the sealing sleeve and the brake shaft and communicating with the fluid chamber, wherein the sealing sleeve has a flux guide that guides magnetic flux to the brake shaft through the seal gap, the brake shaft has a magnetic shaft extending in an axis direction, a regulation layer that regulates the magnetic flux by covering an outer circumference surface of the magnetic shaft, and an exposing part opposing to the flux guide, the brake shaft being exposed from the regulation layer through the exposing part.