Patent ID: 7893579

Claim:
An electric motor comprising a stator ( 124 ) having a bearing tube, which tube is implemented, at least in a subregion, from a magnetically transparent material; a rotor ( 38 ; 112 ) having a rotor shaft ( 40 ; 232 ) and having a rotor magnet ( 38 ; 228 ) having n pole pairs; a ring magnet fixedly connected to the shaft ( 40 ; 232 ), and arranged at least partially in the bearing tube, which magnet is magnetized in such a way that it has a maximum of n pole pairs, where n is a positive integer and that a substantially sinusoidal magnetic flux profile occurs at its circumference; at least one rotor position sensor ( 84 ′, 84 ″; 248 ′, 248 ″) for generating a rotor position signal that maps a property of the magnetic flux from said ring magnet and is suitable for ascertaining an absolute value of the rotor position, said at least one rotor position sensor being arranged outside the ring magnet ( 82 ; 250 ) being arranged at least partially between the rotor shaft ( 232 ) and the at least one rotor position sensor ( 84 ′, 84 ″; 248 ′, 248 ″).