Tone wheel and method of magnetizing the same and method of manufacturing such tone wheel

Abstract

A tone wheel includes a cylindrical elastic multipole magnet formed by a cylindrical elastic inner lining element and a metallic ring in which the cylindrical elastic inner lining element is shaped into a cylindrical form from a composite material including a mixture composed of any suitable elastic material and any suitable powdery ferromagnetic material, and is disposed inside the metallic ring in such a way that its inner circumferential surface is inclined at a predetermined angle of inclination “&thgr;” with regard to the center axis through the cylindrical elastic inner lining element. A magnetizing yoke is further included, wherein the yoke has its outer circumferential wall formed to have the angle of inclination corresponding to the predetermined angle of inclination “&thgr;” of the cylindrical elastic inner lining element, and provides alternating S and N (or N and S) polarity pattern in the circumferential direction of the outer circumferential wall. When the yoke is brought closer to the cylindrical elastic inner lining element until the outer circumferential wall of the yoke can engage the inner circumferential surface of the cylindrical elastic inner lining element, the inner circumferential surface may be magnetized by the yoke, forming a magnetic pole face carrying the alternating N and S (or S and N) polarity pattern that exactly matches the reversed pattern of the alternating S and N (or N and S) polarity pattern of the magnetizing yoke.