Compact low noise efficient blower for cpap devices

A blower comprising:

• an electric motor case including a motor external wall, and a shaft that 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 first direction generally parallel to the shaft axis;
• a first impeller attached to the shaft on a first side of the motor and adapted to accelerate gas tangentially and to direct it radially outward;
• a stationary portion including
• an annular gas flow path defined between the motor external wall and a wall of the stationary portion, said annular flow path being of sufficient width to allow a flow of gas therethrough without introducing excessive pressure drop, said annular flow path directing gas to flow in a generally axial direction from the first side of the motor to a second side of the motor;
• said stationary portion further including a first stator vane structure, said first stator vane structure defining a plurality of stator vane leading edges, said first stator vane have an inner end, the first stator vane structure being located on the second side of the motor and arranged to smoothly direct gas flow along a curved path, said curved path directing flow at the inner end of the first stator vane structure in a generally radially inward direction;
• the blower being structured and arranged such that the motor case provides a shielding function for said stator vane leading edges from an impeller blade pressure pulse.