Patent ID: 8297949
Filing Date: 2012-10-30
Classification: F04D,F16C

Abstract:
1. A motor comprising: a stator; a rotor in proximity with the stator; a housing assembly supporting the stator, the housing assembly includes a discharge housing that defines a discharge opening; a shaft extending from the rotor into the discharge housing; an impeller attached to the shaft such that the impeller and the rotor rotate as a unit to provide discharge air pressure at the discharge opening; a bearing supported by the housing assembly, the bearing supports the shaft and is axially interposed between the rotor and the impeller; and an external seal proximate the bearing and encircling the shaft, the seal includes a motor side and a turbine side, the motor side generally faces toward the rotor and the turbine side generally faces toward the impeller, the motor side being exposed to upstream air pressure, the turbine side being exposed to downstream air pressure, the downstream air pressure is less than the upstream air pressure and is less than the discharge air pressure, the downstream air pressure is at subatmospheric pressure, the upstream air pressure urges the seal against an axial abutment surface on at least one of the bearing, the shaft and the housing assembly, wherein a radial air clearance exists at one of the following: a) at an outermost radial periphery of the external seal, and b) at an innermost radial periphery of the external seal.