Patent ID: 8066575

Claim:
A constant velocity universal joint, comprising: a shaft; a lock member; an outer member; an inner member; and a torque transmission member intervening between the outer member and the inner member to transmit torque, wherein the inner member comprises (i) a shaft hole formed in the inner member for spline-fitting a shaft to the inner member by inserting the shaft into the shaft hole so as to prevent the shaft from coming off by the lock member, (ii) a protrusion provided at a shaft insertion side end portion of the inner member, and (iii) a two-step chamfer of different chamfer angles provided at the shaft insertion side end portion of the shaft hole, wherein the two-step chamfer includes a first chamfer section situated on a shaft hole opening side of the inner member and a second chamfer section provided on a side opposite to the shaft hole opening so as to be continuous with the first chamfer section, wherein the chamfer angle of the first chamfer section is larger than the chamfer angle of the second chamfer section, wherein the first chamfer section is provided at an inner peripheral surface of the protrusion, and the first chamfer section automatically aligns the locking member and the second chamfer section reduces a diameter of the locking member, wherein the first chamfer section meets the second chamfer section at a boundary portion disposed between the first chamfer section and the second chamfer section, wherein a radius of the boundary portion is larger than a maximum radius of the lock member, wherein the shaft is spline-fitted to the inner member by inserting the shaft into the shaft hole such that the lock member prevents the shaft from coming off.