| CPC F04D 19/002 (2013.01) [F04D 25/06 (2013.01); F04D 25/08 (2013.01); F04D 29/056 (2013.01); F04D 29/06 (2013.01); F04D 29/5806 (2013.01)] | 12 Claims |

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1. A method for operating an impeller assembly, the impeller assembly comprising:
an impeller housing (15);
a motor housing (19) arranged in the impeller housing, said motor housing (19) including a main space (38), a front cavity (36), and a bearing receptacle (34), said bearing receptacle including a recess (40);
a motor (16) arranged in an interior space (36, 38) of the motor housing (19), the motor including a motor shaft (17);
an impeller rotor (14) coupled to the motor shaft (17); and
a main bearing (33) in the bearing receptacle (34) arranged between the motor (16) and the impeller rotor (14), a sealing gap (37) defined between the motor housing (19) and the motor shaft (17) between the main bearing (33) and the impeller rotor (14),
wherein the front cavity (36) is arranged between the main bearing (33) and the impeller rotor (14), a compensation channel (41) bypassing the main bearing (33) is defined between the front cavity (36) and the main space (38), a portion of the compensation channel (41) is formed between the recess (40) and the main bearing (33), the motor (16) drives the impeller rotor (14) to generate an air stream along an annular space (31) formed between the impeller housing (15) and the motor housing (19), said method comprising:
applying a positive pressure in the interior space (36, 38) of the motor housing (19), to generate a leakage flow directed from the interior space (36, 38) of the motor housing (19) outward through the sealing gap (37).
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