Hub Unit Bearing

A hub unit bearing comprising;

• an outer ring member having an outer raceway on an inner circumferential surface of the outer ring member;
• an inner ring member having an inner raceway on an outer circumferential surface of the inner ring member and a spline hole formed on a center section of the inner ring member;
• a plurality of rolling elements provided on the outer raceway and the inner raceway;
• an encoder supported at a portion near an inside end section in an axial direction of the inner ring member;
• a cover formed into a circular ring shape and fastened around a portion of an inside end section in the axial direction of the outer ring member,
• a sensor supported by the cover;
• a seal ring fastened on a small-diameter stepped section that is formed around the inside end section in the axial direction of the inner ring member and closing off a sensing space where the encoder and a detecting section of the sensor are located from an outside space;
• and
• a combined seal ring provided between the inside end section in the axial direction on the inner circumferential surface of the outer ring member and the portion near the inside section in the axial direction on the outer circumferential surface of the inner ring member, to which the encoder is attached and fixed;
• wherein the cover comprises:
• a large-diameter cylindrical section fitted onto and fastened to the inside end section in the axial direction of the outer ring member;
• a side wall section formed by bending inward in a radial direction from an inside end section in the axial direction of the large-diameter cylindrical section, with an outside surface in the axial direction of the side wall section coming in contact with an inside end surface in the axial direction of the outer ring member;
• a small-diameter cylindrical section formed by bending inward in the axial direction from an inside end section in the radial direction of the side wall section;
• a disk section formed by bending inward in the radial direction from an inside end section in the axial direction of the small-diameter cylindrical section;
• an inner-diameter cylindrical section formed by bending outward in the axial direction from an inside end section in the radial direction of the disk section and having an inner circumferential surface with which a tip end edge of a seal member made of elastic material of the seal ring comes in sliding contact all around in a circumferential direction,
• a water drainage hole formed in a portion that is located at a bottom of the cover during operation and between the small-diameter cylindrical section and the side wall section so as to drain any foreign matter which enters inside the sensing space to the outside space, a bottom end section of a portion of the water drainage hole that is opened in the side wall section being located in a middle section in the radial direction of the side wall section and located further downward than a bottom end section of the inner circumferential surface of the inside end section in the axial direction of the outer ring member;
• and
• a cover section formed further on an outside in the radial direction of the side wall section than the portion of the water drainage hole that is opened in the side wall section.