Patent ID: 8356940

Claim:
A wheel bearing apparatus incorporating a rotational speed detecting apparatus comprising: an outer member integrally formed, on its inner circumference, with double row outer raceway surfaces; an inner member including a wheel hub and at least one inner ring, the wheel hub is integrally formed, on its one end, with a wheel mounting flange, a cylindrical portion axially extends from the wheel mounting flange, the inner ring is press fit onto the cylindrical portion of the wheel hub, the wheel hub and the inner ring are formed, on their outer circumferences, with double row inner raceway surfaces that oppose the double row outer raceway surfaces; double row rolling elements are contained between the inner and outer raceway surfaces of the inner and outer members; a pulser ring is adapted to fit onto the outer circumference of the inner ring and secures to it, the pulser ring has a magnetic characteristics alternately and equidistantly varying along its circumferential direction; a cylindrical sensor cap has a bottom formed by plastic injection molding, the sensor cap is adapted to be fit into and secures to the inner circumference of an inner-side end of the outer member; a mounting portion axially projects from a radially outer portion of the sensor cap, an inserting bore is formed in the mounting portion so that it axially extends at a position corresponding to the pulser ring; a sensor unit is mounted in the inserting bore, a rotational speed sensor is embedded in the sensor unit, the speed sensor opposes the pulser ring via a predetermined axial air gap; an extending portion having two substantially parallel side walls that extend from the mounting portion and a position of a gate of a mold is set on the extending portion of the sensor cap.