BEARING DEVICE FOR WHEEL

摘要

[PROBLEMS] A bearing device for a wheel, where contradictory problems of weight-lightness/compactness and high strength/rigidity are solved. [MEANS FOR SOLVING PROBLEMS] The bearing device for a wheel is of a third generation structure, in which a predetermined hardened layer (23) is formed by induction hardening, from a base (7c) of a hub ring (5) to the outer periphery of a small-diameter step section (5b). Of rolling bodies, those on the outer side are balls (3) and those on the inner side are conical rollers (4). The pitch circle diameter PCDi of the conical rollers (4) is set smaller than the pitch circle diameter PCDo of the balls (3). A mortar-like recess (17) is formed in the end on the outer side of the hub ring (5), and the bottom of the mortar-like recess (17) is located about the groove bottom of an inner raceway surface (5a) of the hub ring (5). The thickness of the hub ring (5) in the direction of the contact angle a of the balls (3) is set to a range from 0.2 to 0.3 times the diameter of that portion of the hub ring (5), and the outer side of the hub ring (5) has a uniform thickness corresponding to the recess (17) with the thickness equal to or two times the depth of an effective hardened layer of the hardened layer (23).