Patent ID: 8104970

Claim:
A vehicle wheel bearing apparatus comprising: an outer member formed with a body mounting flange on its outer circumference, the body mounting flange is to be mounted on part of a suspension apparatus of the vehicle, an inner circumference of the outer member includes double row outer raceway surfaces; an inner member includes a wheel hub and an inner ring or an outer joint member of a constant velocity universal joint, the wheel hub is formed, on one end, with a wheel mounting flange, an outer circumference of the wheel hub includes one inner raceway surface positioned opposite to one of the double row outer raceway surfaces, a cylindrical portion axially extends from the inner raceway surface, and the inner ring is press-fit onto the cylindrical portion of the wheel hub, an outer circumference of the inner ring includes the other inner raceway surface positioned opposite to the other of the double row outer raceway surfaces; double row rolling elements are freely rollably contained between the inner raceway surfaces of the inner member and the outer raceway surfaces of the outer member; seals are mounted within annular openings formed between the outer member and the inner member, an outer side seal of the seals slidably contacts a base of the wheel mounting flange, the base has a circular arc cross-section on an inner side of the wheel mounting flange; a stepped portion is formed between an inner side surface of the wheel mounting flange and its base, the stepped portion is formed with a combined circular arc cross-section wherein the combined circular arc cross-section is positioned between the wheel mounting flange and a corner edge of the stepped portion, and the combined circular arc cross-section having two predetermined radii of curvatures; and an annular recessed portion is formed on an inner circumference of the outer side end of the outer member, the recessed portion is formed opposite to the corner edge of the stepped portion via a small gap, the gap forms an annular labyrinth seal having a substantially “L” shaped cross-section.