JPH1137146A5 - - Google Patents

Description

The other axial end face (right end face in FIG. 1) of the first inner ring member 3a and the step 31 provided on the outer peripheral surface of the middle part of the second inner ring member 4a do not come into complete contact even after preload is applied by the nut 30 as described above (there is at least a minute gap, or they only come into contact with an extremely low contact pressure). Also, an engaging groove 32 is formed around the entire periphery on the outer peripheral surface of the housing portion 9a of the constant velocity joint 22a that constitutes the other end (right end face in FIG. 1) of the second inner ring member 4a, for engaging one end of a cylindrical boot (not shown) that closes the end opening of this housing portion 9a .

The wheel rolling bearing unit of this embodiment configured as described above functions to rotatably support a wheel relative to a suspension system in the same manner as in the conventional wheel rolling bearing unit described above. In particular, in this embodiment, the diameter of the circumscribing circle of each outer engagement groove 25 is made smaller than the diameter of the second inner ring raceway 10, so that the second inner ring raceway 10 and a portion of the outer engagement groove 25 overlap each other in the diametrical direction. Therefore, this overlapping allows the axial dimension of the wheel rolling bearing unit to be reduced, thereby making the entire device smaller and lighter.