Bearing Apparatus for a Wheel of Vehicle

A bearing apparatus comprising:

• an outer member formed with double row outer raceway surfaces on its inner circumferential surface;
• an inner member including a wheel hub with a wheel mounting flange integrally formed at one end, hub bolts are adapted to be mounted on the wheel mounting flange equidistantly along its outer periphery, one inner raceway surface is formed on the outer circumferential surface opposite to one of the double row outer raceway surfaces and a cylindrical portion axially extends from the inner raceway surface;
• an inner ring is press fit onto the cylindrical portion, the inner ring is formed, on its outer circumferential surface, with the other inner raceway surface opposite to the other raceway surface of the double row outer raceway surfaces;
• double row groups of balls are freely rollably contained between the outer raceway surfaces and inner raceway surfaces, respectively, of the outer member and the inner members;
• a pitch circle diameter of the outer side ball group is larger than a pitch circle diameter of the inner side ball group;
• and
• ribs are formed on a surface of the inner side of the wheel mounting flange, each rib is formed by an outline including straight portions, radially extending outwardly from the base of the wheel mounting flange, and a rounded tip portion, having a predetermined radius of curvature centered on the axial center of hub bolt and substantially corresponding to a distance between the axial center and the outermost periphery of the wheel mounting flange.

A vehicle wheel bearing apparatus comprising:

• an outer member formed with a body mounting flange on its outer circumferential surface, said body mounting flange adapted to be mounted on an automobile knuckle, and said outer member formed with double row outer raceway surfaces on its inner circumferential surface;
• an inner member formed on its outer circumferential surface with double row inner raceway surfaces, respectively, opposite to the other raceway surface;
• double row groups of balls are freely rollably contained between the outer raceway surfaces and inner raceway surfaces, respectively, of the outer member and the inner members;
• the body mounting flange formed with four apertures to receive bolts to fasten to a knuckle, said body mounting flange also formed with recesses, each having a smoothly curved configuration on its outermost periphery between the bolt apertures;
• a pitch circle diameter of the ball group of the outer side is larger than a pitch circle diameter of the ball group of the inner side;
• and
• a pitch of bolt apertures in a loading direction is larger than a pitch of bolt apertures in a direction orthogonal to the loading direction.