Patent ID: 7228933
Filing Date: 2007-06-12
Classification: B62D,F16D

Abstract:
1. An electric power steering device for transmitting rotation of a steering assisting electric motor to a steering mechanism through a small gear and a large gear, comprising: a first member on a rotary shaft of said electric motor; a second member at one end of the small gear; and an elastic member between the first and second members for transmitting a torque between the two members, wherein said elastic member has a first torsional elastic modulus when a torsion angle between the first and second members is less than a predetermined angle, and a second torsional elastic modulus when said torsion angle is one of equal to and larger than the predetermined angle, wherein said first torsional elastic modulus is smaller than said second torsional elastic modulus, wherein said elastic member comprises a radially and axially extending plate-shaped portion, wherein at least one of said elastic member and said first and second members comprises a circumferentially extending projection at an outer periphery, wherein, if said elastic member comprises said circumferentially extending projection, then the circumferentially extending projection contacts said first and second members when no torque or low torque is applied to one of said first and second members, and wherein, if at least one of said first and second members comprises said circumferentially extending projection, then a radially extending surface of the circumferentially extending projection contacts said elastic member when no torque or low torque is applied to one of said first and second members.