| 摘要 |
PROBLEM TO BE SOLVED: To prevent decrease in rolling fatigue life of a wheel bearing and occurrence of cracking caused by generation of hoop stress, and achieve weight reduction by shortening a stem portion.SOLUTION: A wheel bearing device includes a wheel bearing 20 comprising an outer ring 5, a hub ring 1 and inner ring 2, and a plurality of rows of rolling elements 3, 4 interposed between outer raceway surfaces 13, 14 of the outer ring 5 and inner raceway surfaces 7, 8 of the hub ring 1 and inner ring 2, wherein a constant velocity universal joint 6 is coupled to the wheel bearing 20 by means of a thread fastening structure N by fitting a stem portion 30 of an outer joint member 24 of the constant velocity universal joint 6 into the hub ring 1. In the wheel bearing device, a PCD of the rolling elements 4 on an inboard side is made larger than a PCD of the rolling elements 3 on an outboard side, and a concave-convex fitting structure M wherein a plurality of convex portions 37 formed on the stem portion 30 and extending in an axial direction are press-fitted into the hub ring 1 to transfer the shape of the convex portions 37 to the hub ring 1 and thereby entire regions X of fitting contact areas between the convex portions 37 and concave portions 40 come in close contact with each other is placed on an inboard side with respect to a bearing center L. |
