Fixed type constant velocity universal joint

A fixed type constant velocity universal joint, comprising:

• an outer joint member having a spherical inner peripheral surface in which a plurality of track grooves are formed so as to extend in an axial direction, the outer joint member having an opening side and a depth side spaced apart from each other in the axial direction;
• an inner joint member having a spherical outer peripheral surface in which a plurality of track grooves are formed so as to be paired with the track grooves of the outer joint member;
• a plurality of balls, which are interposed between the track grooves of the outer joint member and the track grooves of the inner joint member, and are configured to transmit torque;
• and
• a cage, which is configured to retain the balls, and has a spherical outer peripheral surface to be fitted to the spherical inner peripheral surface of the outer joint member, and a spherical inner peripheral surface to be fitted to the spherical outer peripheral surface of the inner joint member,
• wherein the track grooves of the outer joint member comprise:
• first track groove portions (7a) located on the depth side;
• and
• second track groove portions (7b) located on the opening side,
• wherein the first track groove portions (7a) each have a ball raceway center line (Xa) having a single curvature radius (R1) with a curvature center that is prevented from being offset in the axial direction with respect to a joint center (O),
• wherein planes (M) each including the ball raceway center line (Xa) and the joint center (O) that are inclined with respect to a joint axial line (N-N) so that the planes (M) are inclined in directions opposite to each other in the first track groove portions (7a) that are adjacent to each other in a circumferential direction,
• wherein an end portion (A) of the ball raceway center line (Xa) of each of the first track groove portions (7a) is located on the opening side with respect to the joint center (O),
• wherein a ball raceway center line (Xb) of each of the second track groove portions (7b) is connected to the end portion (A),
• wherein a ball raceway center line (Y) of each of the track grooves of the inner joint member is formed so as to be mirror-image symmetrical with a ball raceway center line of corresponding one of the paired track grooves of the outer joint member with respect to a plane (P) that includes the joint center (O) at an operating angle of 0° and is orthogonal to the joint axial line (N-N),
• wherein the ball raceway center line (Xb) of the each of the second track groove portions (7b) has a single curvature radius (R2) with a curvature center that is offset in a radial direction with respect to the joint axial line (N-N), and
• wherein the curvature radius (R2) is set larger than the curvature radius (R1).