A silencing device includes: a flow path forming plate having a flow path forming surface for forming a wall surface of a flow path through which fluid flows; and a cavity defining portion for defining a cavity on the reverse surface side of the flow path forming plate, the reverse surface being located on the reverse side of the flow path forming surface. The flow path forming plate has formed therein a plurality of fine through-holes which are configured to provide communication between the flow path forming surface and the reverse surface and which has a diameter from 0.01 mm to 0.5 mm.

The application discloses a noise attenuating system (100, 200, 300, 400, 700, 800) for use with a positive airway pressure system providing a flow of gas, comprising: an expansion chamber (140, 240, 340, 434, 740) having a volume; an intake tube (115, 215, 315, 415, 715, 815) having an inlet (117, 217, 317, 410, 717, 812) and outlet port or portion separated by a length, wherein a portion of the inlet port or portion extends outside of the expansion chamber; and either: a noise attenuator (110, 120, 170, 210, 220, 223, 224, 226, 228, 232, 270, 320, 411, 413, 422, 423, 424, 425, 426, 428, 431, 720, 722) having a bottom and protruding sidewall forming a cavity, wherein the noise attenuator is positioned near the inlet portion of the intake tube such that a portion of the intake tube extends into the cavity of the noise attenuator; or: an acoustic deflector (110, 120, 170, 210, 220, 223, 224, 226, 228, 270, 232, 320, 411, 413, 422, 423, 424, 425, 426, 428, 431, 720, 722) positioned near the outlet port or portion of the intake tube, wherein noise is deflected away from the outlet port or portion of the intake tube. The application also discloses positive air pressure apparatus (100, 200, 300, 400, 700, 800) comprising a housing (180, 480, 880, 884), first and second acoustic chambers, an intake vent or port (125, 225, 410, 812) in the first chamber, an inlet port or tube coupling the first and second chambers, a noise attenuator in the first chamber, and a blower unit (150, 250, 350, 440) in the second chamber.

A blower for a breathing apparatus has a diffuser for increasing static pressure and/or reducing noise and/or mitigating pressure instabilities and/or managing reverse flow.

A fan includes an impeller including a boss serving as a center of rotation and a plurality of blades provided on an outer circumferential surface of the boss, and a structure member installed on an upstream side of the impeller in an airflow direction. The plurality of blades each have a plurality of recesses disposed only on a side of a suction surface of a leading edge. The plurality of recesses each have a rectangular shape having two longitudinal sides. Consequently, it is possible to reduce fluctuations of lift on the plurality of blades and thereby reduce discrete frequency noise.

A fan includes: a housing; and an impeller with an axis and a plurality of blades, the impeller mounted inside the housing; and a plurality of outlets from the housing, each outlet including a cutoff with a top and a bottom. A line between the top and bottom of each cutoff is not parallel to the axis of the impeller.

Disclosed embodiments relate to a housing for a fan that is constructed by cutting, bending, and/or folding a single sheet of metal. A disclosed housing is configured to house a fan having a motor that is configured to rotate around an axial direction. The housing includes a first plate that is oriented in a plane that is perpendicular to the axial direction and substantially flat wall regions extending away from the first plate so as to be non-coplanar with the first plate. The housing further includes a second plate having an air intake nozzle, the second plate oriented perpendicularly to the axial direction and thereby oriented parallel to the first plate and located a first distance along the axial direction from the first plate, with the first distance being determined by a length of the wall regions. The wall regions are configured to include air flow openings.

A motor-fan assembly includes a motor assembly having a rotatable shaft extending therethrough and a working fan assembly having at least one working fan rotated by the rotatable shaft. The motor-fan assembly includes a motor cover that substantially encloses the motor assembly. The motor assembly provides a cover opening extending therethrough and the rotatable shaft extends through the opening. The motor-fan assembly also includes a cooling fan assembly with at least one cooling fan rotated by the rotatable shaft which fan draws cooling airflow over the motor assembly. A motor vent cover is coupled to the motor cover with the at least one cooling fan therebetween. The motor vent cover has a cooling air outlet through which cooling airflow is exhausted.

A blower configured for a breathing apparatus which can have a diffuser for increasing static pressure and/or reducing noise and/or mitigating pressure instabilities and/or managing reverse flow. The diffuser can be located within a housing, such as along with a motor, between an impeller and an outlet. The diffuser can include diffuser elements arranged in cascades, and can include one or more circumferential rings to direct air.

A motor-fan assembly includes an assembly housing which supports a motor assembly, a working fan assembly which includes a working fan rotated by the motor assembly which draws in and exhausts working air, and a cooling fan assembly which includes a cooling fan rotated by the motor assembly which draws in and exhausts cooling air. The assembly housing includes a motor vent cover associated with the cooling fan assembly, wherein the motor vent cover further includes a sidewall with at least one vent hole therethrough and at least one socket aligned with the at least one vent hole. The assembly also includes a body having a tube opening extending therethrough, and an inner facing surface with at least one tail receivable in the at least one socket so that the at least one vent hole is contiguous with the tube opening.

A propeller fan includes a boss on a rotation axis, and a blade at an outer circumferential portion of the boss. The blade includes a leading edge and a trailing edge. The blade includes a first area, a first sub-area located inward of the first area, and a second sub-area located outward of the first area. The first area includes a notch formed in the trailing edge. Each of the first sub-area and the second sub-area include plural notches formed in the trailing edge. The notch in the first area is larger than each of the plural notches in each of the first sub-area and the second sub-area.