Patent ID: 7448298

Claim:
A viscous damper comprising a case with an opening toward one side in an axial direction of an annular case body substantially U-shaped in section being closed with a fixed cover to be liquid-sealed, an annular inertia mass element housed with a damping liquid inside said case, and support means for supporting said inertia mass element in a circumferential direction inside said case, wherein said inertia mass element is comprised of a laminate of annular plates, each plate being formed of arc-shaped ring pieces bonded together in a circumferential direction and a width direction, in which a protruded piece or a fitting hole in the circumferential direction fitted to the protruded piece is formed at one end of each said arc-shaped ring piece, said hole or said protruded piece is formed at the other end of said arc-shaped ring piece, a concave portion is formed at both sides of a base portion of said protruded piece, and a convex portion fitted in the concave portion is formed at an open end of said hole.