597253 A blower (100) for a CPAP ventilator is disclosed. The blower has an electric motor (140) case including a motor external wall, and a shaft (160) that defines a shaft axis. A housing (172, 174) with a housing inlet (130) and a housing outlet (120) between defines a flow path for gas. The gas is directed out the outlet direction parallel to the shaft axis. A first impeller (150) is 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 includes an external housing in two parts (172, 174) and an assembly of internal flow directing components including three sets of stator components (180, 182, 184) and two shields (190, 192). Between the motor external wall and a wall of the stationary portion an annular gas flow path defined. The annular flow path is of sufficient width to allow a flow of gas there through without introducing excessive pressure drop. The annular flow path is in an axial direction from the first side of the motor to a second side of the motor. The stationary portion further including a first stator vane structure (180) the first stator vane structure defining a plurality of stator vane leading edges (185). The first stator vane has 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, the curved path directing flow at the inner end of the first stator vane structure in a radially inward direction. The blower is structured and arranged such that the motor case provides a shielding function for the stator vane leading edges from a pressure pulse from the impeller.
