Patent ID: 8569922

Claim:
An electric motor comprising: a stator ( 28 ) having a stator lamination stack ( 27 ) defining a plurality of slots ( 126 ); a stator winding (U, V, W) arranged in said slots ( 126 ); a rotor ( 36 ) separated from the stator ( 28 ) by a magnetically effective air gap ( 39 ), which rotor includes, on its side facing toward said air gap ( 39 ), a plurality of salient poles ( 136 A, 136 B, . . . ) having pole shoes ( 136 ) facing toward said air gap ( 39 ), and on its side facing away from the air gap ( 39 ) a magnetic yoke ( 130 ) that is mechanically connected to the pole shoes ( 136 ) by respective holding segments ( 132 , 134 a , 134 b ); a respective recess ( 160 ) formed between the magnetic yoke ( 130 ) and a respective pole shoe ( 136 ), in which recess, in order to generate a magnetic flux in said pole shoe ( 136 ), at least one permanent magnet ( 38 ) is arranged, thereby defining a respective magnet/pole shoe boundary ( 138 ) at each transition from said permanent magnet to the associated pole shoe, and which recess ( 160 ) is adjoined, on each circumferential side of the at least one permanent magnet ( 38 ) by a region ( 146 a , 146 b ) of poor magnetic conductivity that is contiguous, on its side facing toward the air gap ( 39 ), with one of the holding segments ( 134 a , 134 b ), wherein the width (β), measured in a circumferential direction, of a pole shoe ( 136 ) decreases, at least locally, in a direction away from the magnet/pole shoe boundary ( 138 ) toward the air gap ( 39 ) in a transition zone to a point ( 142 ) of least pole shoe width, in said transition zone, a pole shoe ( 136 ) defines, on each of its sides facing toward the adjacent pole shoe ( 136 ), a flank ( 139 ), and the holding segments ( 134 a , 134 b ) are configured as spring elements that mechanically urge the pole shoes ( 136 ) in a direction toward the associated permanent magnets ( 38 ), in order to retain said permanent magnets in the recesses ( 160 ) provided for them.