Patent ID: 7270606

Claim:
A power transmission device comprising: a drive rotor rotated by external power; and a driven rotor rotated by the drive rotor, wherein a plurality of protrusions are provided in the drive rotor and the driven rotor so as to be circumferentially spaced apart and axially protrude facing circumferentially each other, a block-shaped shock absorbing rubber being placed between each protrusion of the drive rotor and each protrusion of the driven rotor, and torque of the drive rotor being transmitted to the driven rotor via each shock absorbing rubber, wherein an elastic member that presses the shock absorbing rubber circumferentially of the drive rotor and the driven rotor is provided between the shock absorbing rubber and the protrusion, a part of the elastic member directly engages the protrusion of the drive rotor or the driven rotor, and another part of the elastic member biases the shock absorbing rubber towards an adjacent protrusion of the drive rotor or the driven rotor, wherein said elastic member is placed between the shock absorbing rubber and the protrusion previously in a compressed state so as to be elastically deformed and wherein said elastic member comprises a pair of elastic pieces that abut against shock absorbing rubbers placed on both sides of the protrusion are formed in opposite ends of the elastic member.