Compact low noise efficient blower for CPAP devices

A blower comprising:

• an electric motor having a shaft, said shaft defines a shaft axis;
• a housing having a housing inlet and a housing outlet between which is defined a flow path for gas;
• the housing outlet is structured to direct gas exiting the blower in a substantially axial first direction;
• the motor has a first side proximal said housing inlet, and a second side distal said housing inlet;
• a first impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward and being attached to the shaft on the first side of the motor;
• a stationary portion including:
• a gas flow path defined between an external wall of the motor and a wall of the stationary portion, said flow path being of sufficient width to allow a flow of gas therethrough without introducing excessive pressure drop, said flow path directing gas to flow in a generally axial direction from the first side of the motor to the second side of the motor;
• a first stationary vane structure located downstream of the first impeller, the first stationary vane structure adapted to direct gas exiting the first impeller from flowing in a substantially tangential direction to flowing in both a radial and axial direction;
• and
• a shield constructed and arranged to provide a barrier between the first stationary vane structure and the blades of the first impeller to isolate leading edges of the first stationary vane structure from an impeller blade pressure pulse;
• and
• a second impeller attached to the shaft on the second side of the motor, the second impeller adapted to receive a flow of gas flowing in said first direction exiting from said first stationary vane structure.