Patent ID: 8757887

Claim:
A bearing device for a wheel, the bearing device comprising: a constant velocity universal joint including an outer joint member having a shaft section; and a double-row rolling bearing comprising: an outer member having an inner circumference in which double-row outer raceway surfaces are formed; an inner member comprising an inner race and a hub wheel with a hole to which the shaft section of the outer joint member is fitted and coupled and a flange for attachment to a wheel, the inner member having, on an outer circumference thereof, inner raceway surfaces in double rows that oppose the double-row outer raceway surfaces; and rolling elements in double rows interposed between the double-row outer raceway surfaces of the outer member and the inner raceway surfaces of the inner member, wherein the hub wheel and the shaft section of the outer joint member of the constant velocity universal joint are integrated with each other by a recess-projection fitting structure, wherein the recess-projection fitting structure includes projections, which are provided on one of an outer surface of the shaft section of the outer joint member and an inner surface of the hole of the hub wheel so as to extend in an axial direction, that are press-fitted to another of the outer surface of the shaft section of the outer joint member and the inner surface of the hole of the hub wheel, and recesses, which intimately fit with the projections and are formed in the other of the outer surface of the shaft section of the outer joint member and the inner surface of the hole of the hub wheel, such that entire regions of fitting contact regions between the projections and the recesses are brought into intimate contact with each other, wherein an outer surface side of the hub wheel has an induction hardened layer formed thereon, and an inner surface side of the hub wheel is in an unhardened state, and wherein the projections cut into the other of the outer surface of the shaft section of the outer joint member and the inner surface of the hole of the hub wheel to form surfaces of the recesses, and the recess-projection fitting structure is formed by press-fitting the projections into the other of the outer surface of the shaft section of the outer joint member and the inner surface of the hole of the hub wheel.