Patent ID: 7709987
Filing Date: 2010-05-04
Classification: H02K

Abstract:
1. A magneto rotor comprising: a cup-like rotor yoke having a peripheral wall portion and a bottom wall portion formed at one axial end of said peripheral wall portion, the other axial end of said peripheral wall portion being an open end; a plurality of permanent magnets arranged circumferentially of said rotor yoke and secured to an inner periphery of said peripheral wall portion; and a magnet protecting cover that has a cylindrical portion covering inner peripheries of said plurality of permanent magnets and an outer flange integrally formed with one axial end of said cylindrical portion, and is placed so that said cylindrical portion is positioned inside said plurality of permanent magnets and said outer flange covers outer end surfaces of said permanent magnets at the open end of said rotor yoke, wherein an inner diameter of the peripheral wall portion near the open end of said rotor yoke is enlarged, and an annular abutting surface continuing circumferentially of said rotor yoke is formed on a step formed between a portion with the enlarged inner diameter of said peripheral wall portion and an other portion, said outer flange of said magnet protecting cover is provided so as to extend beyond said outer end surfaces of said plurality of permanent magnets and reach said abutting surface, an area closer to said cylindrical portion of said outer flange is curved to protrude toward the opening of said rotor yoke, and thus an annular protrusion protruding toward the opening of said rotor yoke and continuing circumferentially of said rotor yoke is formed on the area closer to said cylindrical portion of said outer flange, an adhesive storage portion continuing circumferentially of said rotor yoke is formed between the portion with the enlarged inner diameter of the peripheral wall portion of said rotor yoke and said annular protrusion of the outer flange of said magnet protecting cover, a groove opening into said adhesive storage portion near said abutting surface and continuing circumferentially of said rotor yoke is formed in the peripheral wall portion closer to the open end of said rotor yoke, and said adhesive storage portion and said groove are filled with the adhesive to seal a boundary between the outer flange of said magnet protecting cover and the peripheral wall portion of said rotor yoke, wherein said groove is provided so that a deepest portion of the groove is positioned closer to the bottom wall portion of said rotor yoke than said abutting surface in the peripheral wall portion of said rotor yoke.