An apparatus is disclosed. The apparatus has a first housing having a first cavity, a second housing disposed in the first housing and including a second cavity and at least one aperture, a first fan assembly configured to generate a first airflow through the first housing, and a second fan assembly configured to generate a second airflow from the second cavity to the first cavity via the at least one aperture.

Ventilation device including a turbine mounted inside a radially volute-shaped casing, the peripheral wall of the casing moving progressively away from the periphery of the turbine from a volute tongue to a distal end (E.sub.2) of the volute, the radial expansion of the volute being defined by an angle of expansion (a.sub.i), characterised by the fact that the initial angle of expansion (a.sub.1) in the vicinity of the volute tongue is 1.5 times to 3 times greater than the final angle of expansion (a.sub.2) in the vicinity of the distal end (E.sub.2) of the volute, so that the peripheral wall of the casing moves away from the blades more rapidly at the start of the volute minimising the turbulences generated at the volute tongue.

A blower includes a housing, and an impeller and a motor received in the housing. The motor drives the impeller to rotate. The motor includes a stator and a rotor. The stator includes a stator core and windings wound around the stator core. The stator core includes a yoke and teeth extending from the yoke. A distal end of each of the teeth forms a tooth tip, with a slot opening formed between each two adjacent tooth tips. The rotor includes a permanent magnet forming a plurality of magnetic poles. The stator and the rotor define an air gap therebetween. A circumferential width of the slot opening is equal to or less than two times of a radial width of the air gap.

A cross-flow fan includes a plurality of fan blades provided to be circumferentially spaced apart from each other. The fan blade has an inner edge portion arranged on the radially inner side to/from which air flows in/out, and an outer edge portion arranged on the radially outer side to/from which air flows in/out. Fan blade has a blade surface extending between the inner edge portion and the outer edge portion. The blade surface includes a pressure surface arranged on the rotation direction side of the cross-flow fan and a suction surface arranged on the back side of the pressure surface. When cut along a plane orthogonal to the rotation axis of the cross-flow fan, the fan blade has a blade cross-sectional shape in which a concave portion concave from the pressure surface is formed.

A modular fan unit of a diagonal and/or axial fan having a housing that includes an inlet opening and an outflow opening. The housing accommodates a fan, that conveys the air at least in the axial direction and is divided perpendicularly to an axis (X-X) of the fan into at least two housing halves that are joined together. The housing forms a chamber in which the blades of the fan rotate around an axis and has a circumferential edge area in the vicinity of which the housing has a thickness B extending in the axis direction of the fan. A motor holding part has a dimension R as the maximum extension in the edge area and the chamber has an extension in the axis direction of the fan at a height of a dimension L, whereas the extension of the air inlet part has a dimension T in the area of the chamber. A ratio of the dimension B to the dimension R with respect to the ratio of the dimension L to the dimension T is within the range from 0.9 to 1.2. The noise emission of the fan during operation is minimized and the outer diameter of the modular fan unit is kept to a minimum.

A noise reduction structure of a supercharger, comprising: a relief channel of the supercharger having a high pressure pipeline and a low pressure pipeline; a silencing assembly which is arranged at a gas communication position between the high pressure pipeline and the low pressure pipeline. The silencing assembly has a plurality of vent holes with a hole diameter smaller than 20 mm, and the silencing assembly is configured in such a way that the high pressure gas only enters the low pressure pipeline after passing through the vent holes when the high pressure pipeline is in communication with the low pressure pipeline. The noise reduction structure of the supercharger mentioned above has good effect of noise elimination during gas release and low costs.

Multiple projections are provided at a flow-change portion, which corresponds to such a portion of a wall surface of an A/C casing, at which velocity gradient of air current becomes larger in an area adjacent to the wall surface, in order to decrease aerodynamic sound generated by disturbed air current.

An airflow device including: (i) airflow generating means for generating first and second streams of air; (ii) first and second Coanda surfaces; (iii) means for directing the first and second streams of air over first and second Coanda surfaces respectively; and wherein (iv) the first stream of air leaving the first Coanda surface is directed so as to pass over the second Coanda surface.

Provided is an electric-assist supercharger configured such that a motor (30) is attached to the end portion of a rotor shaft (15) close to a silencer (26), the rotor shaft (15) being connected to a compressor portion. Such a supercharger includes a suction air introduction path (24) formed in the silencer 26 such that a main suction air flow flows in the radial direction of the silencer (26) toward a connection portion between the silencer (26) and the compressor portion, and a cooling air intake path (40) formed in the silencer (26) in which at least an outlet thereof is on the center axis of the rotor shaft (15).

An air-sending device includes a fan and a grille provided downstream of the fan in a direction of airflow generated by the fan. The grille includes a first grille that includes a plurality of first bars spaced from each other, and a second grille that includes a plurality of second bars spaced from each other. The plurality of second bars are more densely arranged than the plurality of first bars. The second grille is provided upstream of the first grille in the direction of the airflow generated by the fan, and spaced from the first grille to face the first grille.