Patent ID: 7126328

Claim:
A rolling bearing unit with a rotational speed detecting device comprising: an outer ring which has double-row outer ring raceways on its inner peripheral surface, and does not rotate during use; a hub body which has a flange for supporting a wheel on a portion towards an outside end of its outer peripheral surface, and a first inner ring raceway, which faces the outer ring raceway axially outside of the double-row outer ring raceways, is provided on a middle portion either directly or via another member; an inner ring which has a second inner ring raceway, which faces the outer ring raceway axially inside of the double-row outer ring raceways, on an outer peripheral surface, and is externally secured to an inside end of the hub body; a plurality of rolling elements provided so as to be freely rotatable between the outer ring raceways, and each of the first and second inner ring raceways; a supporting ring, formed by bending a magnetic metal plate, which comprises an inner diameter-side cylindrical portion and an outer diameter-side cylindrical portion, which are concentric with each other, connected by a connecting portion, and is fixed to the inner ring by externally securing the inner diameter-side cylindrical portion to a portion at an outer peripheral surface of the inner ring which is away from the second inner ring raceway toward the inside; an encoder which is supported all around the circumference of an outer peripheral surface of the outer diameter-side cylindrical portion constituting the supporting ring, and the characteristics of an outer peripheral surface, which is a part to be detected, are changed alternately relative to the circumference direction; a metal core which is supported and fixed to an inside end of the outer ring; a rotation-detecting sensor in which a detecting portion thereof faces the outer peripheral surface of the encoder in the radial direction, in a state where it is supported by a portion of the metal core; and a seal member which is supported at a proximal end portion thereof by the metal core, and an edge portion thereof is made in a sliding contact all around the circumference of a part of the supporting ring or a part of the inner ring.