Patent ID: 8534922

Claim:
A wheel rolling bearing unit comprising: a rolling bearing which is attached to an outer circumference of a hub shaft of a hub wheel to which a wheel is to be attached, and includes an outer ring; and a cover member fitted in one end side opening of the outer ring of the rolling bearing, wherein the cover member includes a metallic cover main body including integrally a lid portion and a cylindrical portion which projects in an axial direction from an outer circumferential edge of the lid portion and an elastic covering material having elasticity which covers at least one of outer circumferential surfaces of the lid portion and the cylindrical portion of the cover main body, wherein, in a state resulting before the cover member is fitted in the one end side opening of the outer ring, an outside diameter dimension of a cylindrical portion elastic layer of the elastic covering material, which covers an outer circumferential surface of the cylindrical portion of the cover main body, is set to be larger than an inside diameter dimension of an inner circumferential surface of the one end side opening of the outer ring, wherein, in an attached state in which the cover member is fitted in the inner circumferential surface of the one end side opening of the outer ring, the cylindrical portion elastic layer is elastically compressed to be brought into close contact with the inner circumferential surface of the one end side opening of the outer ring, wherein the cylindrical portion of the cover member includes: an annular recess portion formed on the outer circumferential surface of the cylindrical portion so as to extend in an axial direction from the outer circumferential edge of the lid portion and face an inner side of the wheel rolling bearing unit; a step portion formed on a side of the annular recess portion opposite the lid portion; and an outer cylindrical portion extending from the step portion in the axial direction away from the lid portion to an distal end of the cylindrical portion opposite the lid portion, wherein a minimum outer circumferential diameter of the cylindrical portion extending from the step portion to the distal end of the of the cylindrical portion has a diameter greater than a maximum outer circumferential diameter of the cylindrical portion extending from the step portion to the lid portion, wherein the cylindrical portion elastic layer is filled and held in the annular recess portion and makes a filled portion of the annular recess portion into a thick elastically deformable portion, and wherein the elastic layer is disposed on a portion of the outer cylindrical portion.