Patent ID: 8772993

Claim:
An electric motor that comprises: a stator ( 30 ); a rotor ( 26 ) including a cup-like rotor part ( 56 ) having an inner surface ( 58 ) and a ring magnet ( 60 ) adhesively bonded in the latter, which ring magnet ( 60 ) has an outer circumference ( 61 ) on which are formed elevated surfaces ( 84 ) and depressed surfaces ( 86 ) that extend at least partly in a longitudinal direction of the ring magnet ( 60 ); said rotor part ( 56 ) has an open end ( 55 ) adapted for insertion into said ring magnet ( 60 ); and wherein a portion of said ring magnet ( 60 ) which, after assembly, is remote from said open end ( 55 ) of said rotor part ( 56 ), is formed with an oblique surface ( 68 ) whose radial spacing from said inner surface ( 58 ) increases as a function of distance from said open end ( 55 ), said oblique surface ( 68 ) and said rotor part ( 56 ) defining, between them, a circumferentially extending void ( 69 ) which interconnects at least a plurality of said depressed surfaces ( 86 ; 122 ; 164 ; 186 ) formed in said ring magnet.