A cooling fan has a fan shroud with a fan wheel recess surrounded by a shroud ring and a fan wheel rotatably mounted in the fan wheel recess for conveying the air flow along a conveying direction from a shroud upper side to a shroud underside. The fan wheel has a central hub cup with radially orientated blades and an outer ring connecting the blades at the blade tip ends. A circumferential ring gap is formed between the outer ring and the shroud ring. A rib structure in the ring gap reduces swirl in a gap flow orientated against the conveying direction. A shroud ring section of the shroud ring extends axially beyond the outer ring on the shroud underside. The shroud ring section is orientated parallel or at an angle of inclination and radially inwards relative to the conveying direction.

Each of a plurality of blades of a turbofan includes a thick wall portion, a thin wall portion and a stepped portion. The stepped portion is formed between the thick wall portion and the thin wall portion. A plate thickness of the stepped portion is progressively decreased toward a positive pressure surface of the blade in a direction that is directed from the thick wall portion toward the thin wall portion. In the blade, a first curved surface forms a negative pressure surface of the thick wall portion, and a second curved surface forms a negative pressure surface of the thin wall portion while the second curved surface is located on a side of the first curved surface where the positive pressure surface of the blade is placed, and a negative pressure surface of the stepped portion connects between the first curved surface and the second curved surface.

An electric propulsion system for an aircraft includes a nacelle and an electric machine. The electric machine includes a stator positioned in the nacelle, and a rotor and fan assembly positioned in a primary flow path through the nacelle. The rotor and fan assembly includes a cylindrical fan shroud, a plurality of rotor magnets positioned on an outer surface of the fan shroud, and a fan hub mounted on a central support shaft via one or more bearings. A plurality of fan blades extend between an inner surface of the fan shroud and an outer surface of the fan hub. The rotor magnets may be loaded in compression in a radial direction when the rotor and fan assembly is at rest. The fan blades may be pre-stressed in a radial direction when the rotor and fan assembly is at rest.

A ventilation device has a holder, in particular a ventilation frame, with a substantially circular continuous opening for receiving a ventilation wheel rotating about the central axis, thereof. The opening is bordered by an edge face running substantially cylinder-symmetrically about the central axis. As the edge face in two separate, diametrically opposed peripheral sections the radius is at least partly enlarged in comparison to the cylinder-symmetrical form in the remaining peripheral sections, and/or a circular projection of she edge face, which projection projects radially inwards, is axially offset away from a space provided for the ventilation wheel. Because of she corresponding shaping of the edge face of the opening, contact and/or development of noise between the ventilation wheel and the edge of the opening is prevented in the ventilation frame in the event of a yawing of the ventilation wheel.

A centrifugal fan includes an impeller with a base expanded radially, vanes arranged circumferentially, extending from a radially inner side to a radially outer side, and ends thereof at one axial side being connected to the base, and a ring portion connecting ends of the vanes at the other axial side. The vanes include first vanes and second vanes, when viewed axially, the lengths of the second vanes are larger than the lengths of the first vanes, the first vanes and the second vanes are circumferentially arranged alternatingly. Gaps are provided between radially outer ends of the first vanes and the second vanes that are circumferentially adjacent to each other, and sizes of circumferentially adjacent ones of the gaps are different from each other.

A blowing device includes an axil fan having a plurality of blades and causing an air to flow through the blowing device, and a fan shroud rotatably supporting the fan. The fan shroud includes a ring portion surrounding a circumference of the fan, and an air guide portion connecting an outer rim of the fan shroud and an inner rim of the ring portion. The fan shroud includes a specific rim portion that is a part of the outer rim of the fan shroud, a distance from the specific rim portion to the inner rim of the ring portion being shorter than other parts of the outer rim. The fan shroud includes a counter flow introduction passage provided in the air guide portion and extending from a position located inward of the specific rim portion. The blowing device is capable of limiting a rotation noise of the fan.

A blower device includes an axial flow fan having blades to blow air, and a fan shroud that includes a cylindrical portion surrounding an outer circumference of the fan at a distance from the outer circumference, and an air guiding portion guiding air drawn by the fan. The fan shroud includes a short end part shorter in distance to the outer circumference of the fan than another part in an outer end portion of the fan shroud, and a protruding end part provided at a position advanced in a rotational direction from the short end part, protruding upstream in a flow of the drawn air more than the fan and protruding outward of the air guiding portion. Accordingly, the blower device which includes the fan shroud capable of reducing rotational noise can be provided.

The invention relates to a fan wheel having blades (11) which are distributed over the circumference and are connected to one another in the circumferential direction via at least one ring. The fan wheel consists of at least three integrally formed segments (I to VII). Said segments comprise at least one respective ring portion (1) of at least one ring as well as either a blade (II) or at least a portion of the blades. The segments (I to VII) are joined together to form the fan wheel. The ring portions (1) lie against each other with edges (4, 5) which form the joining areas (15, 16) that are disposed transversely with respect to the circumferential direction of the fan wheel. At least one edge (4) of the ring portion (1) of each segment (I to VII) is provided with at least one projecting form-fitting part (18), and at least one edge (4, 5) of the ring portion (1) of each segment (I to VII) is provided with at least one recess (17) which is at least approximately complementary to the form-fitting part (18).

A ceiling fan system wherein the motor of the ceiling fan is housed between the ceiling and the roof of an enclosure within which the ceiling fan is to be used, thereby disposing the motor out of view of occupants within the enclosure where the ceiling fan is being used.

A cooling fan includes a boss section (12) connected to a rotary drive source, a plurality of blades (13) protruding outward from the boss section in a radial direction, and a cylindrical ring member (14) configured to annularly connect the vicinities of end sections outside in the radial direction of the plurality of blades. The plurality of blades (13) protruding outward from the boss section (12) in the radial direction are connected by the cylindrical ring member (14) in the vicinity of the end section outside in the radial direction. An air inlet groove (16) is formed at an end section in an axial direction of an air suction side of the ring member (14). The air inlet groove (16) is disposed between front regions in the rotation direction of all of the blades (13) on the ring member (14) and front regions in the rotation direction of the blades (13) adjacent thereto. The air flowing from the outer circumferential side passes through the air inlet groove (16) of the ring member (14) and gradually changes a direction to be suctioned between the blades (13).