Patent ID: 8162764

Claim:
A constant velocity universal joint comprising: an outer member which is provided with a spherical inner surface in which six track grooves are formed; an inner member which is provided with a spherical outer surface in which six track grooves are formed; six balls disposed in respective wedge-shaped ball tracks formed by the track grooves of the outer member and the track grooves of the inner member; a retainer disposed between the spherical inner surface of the outer member and the spherical outer surface of the inner member to hold the balls; and an elastic member applying an elastic force in an axial direction between the inner member and the retainer to press the balls toward a narrower side of the wedge-shaped ball tracks; wherein a ratio r1 (=PCD BALL /D BALL ) of a pitch circle diameter (PCD BALL ) of the ball to a diameter (D BALL ) of the ball is in a range of 1.5≦r1≦4.0, a ratio R1 is defined by F/PCR, where F is an offset amount between the center of the track grooves of both the inner member and the outer member with respect to a center of the spherical inner surface and the spherical outer surface, and PCR is a length of a segment connecting the center of the inner track grooves with the outer track grooves and the center of the ball, and the ratio R1 (=F/PCR) is in a range of 0.109≦R1≦0.162.