Patent ID: 7140848

Claim:
A method of cooling magnetic bearings ( 5 , 6 , 9 ) of an exhaust gas turbocharger ( 1 ), the exhaust gas turbocharger having a housing and a shaft ( 2 ) rotatable about its longitudinal axis in the housing and on which a turbine wheel ( 4 ) and a compressor wheel ( 3 ) are seated and which is guided in radial bearings ( 5 , 6 ) and in at least one axial bearing ( 9 ), and the bearings ( 5 , 6 , 9 ) having bearing plates which are arranged on the shaft ( 2 ) and stators ( 19 , 20 , 21 , 22 , 49 , 50 ) which are fixed to the housing and are separated from said bearing plates by an air gap, and wherein the radial bearings ( 5 , 6 ) include a plurality of permanent magnets ( 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ) disposed in the air gap between the bearing plates ( 12 , 16 ) and stators ( 19 , 20 , 21 , 22 ), the plurality of permanent magnets ( 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ) being arranged in axially adjacent pairs and being polarized so as to attract one another, whereby an axially directed and attracting magnetic field is produced in the gap between the bearing plates ( 12 , 16 ) and the stators ( 19 , 20 , 21 , 22 ) wherein the bearing gaps have an air stream applied.