A cleaner reduces noise. The cleaner includes a motor, a fan including a number Z of blades and rotatable at a rotational speed N, indicating revolutions per minute, about a rotation axis by the motor, a cover having an inlet located frontward from the fan, and a number V of ribs located in the inlet. The ribs extend in a radial direction from the rotation axis and are arranged in a circumferential direction about the rotation axis. The fan is rotatable to produce noise having a frequency f.sub.NZ of 20,000 Hz or higher, and f.sub.NZ=(m−k×V)×N/60 and m=n×Z+k×V, where n is an order, m is an integer, and k is an integer.

A fan blade (1) has a front leading edge (2) and a rear trailing edge (3). The fan blade (1) has a leading edge (4), at least some portions, that are undulated. The edge forms a wave (W) with a specific three-dimensional waveform.

A fan includes a frame member, a fan body, a surrounding plate and a housing unit. The frame member surrounds an axis and defines an accommodating space in which the fan body is disposed. The fan body is rotatable about the axis. The surrounding plate surrounds the frame member and is formed with at least one plate hole extending in a transverse direction transverse to an axial direction of the axis therethrough. The housing unit surrounds the surrounding plate and has a plurality of housing holes extending in the axial direction of the axis therethrough. The housing unit and the surrounding plate cooperatively define a surrounding space therebetween that is surrounded by the housing holes.

A blowing apparatus includes a housing including an accommodating space and one or more blowing holes and a vibration apparatus in the accommodating space, wherein the vibration apparatus includes a first active vibration member, a second active vibration member connected to an inner lateral surface of the housing and connected to intersect with the first active vibration member, and a passive vibration member between the one or more blowing holes and the first active vibration member and connected to the first active vibration member.

A screw compressor having screw rotors for compressing a process gas, a pipe bend conducting compressed process gas towards a silencer. The pipe bend at an inlet-side portion comprises a first connecting piece fastening the pipe bend to a pressure port and on an outlet-side portion a second connecting piece for fastening the pipe bend to the silencer. The pipe bend has a flow channel between the connecting pieces defined by an inner wall and an insert that projects into the inlet-side portion of the pipe bend. An outer wall of the insert projecting into the flow channel of the pipe bend and a portion of the inner wall of the pipe bend enclosing this outer wall on the outside delimit a space acting as resonator, coupled to the flow channel of the pipe bend.

An air filtration system is described that is suited for CBRN and ColPro applications, and has an integrated inertial particle separator (IPS) and scavenge fan blower as a pre-dust/particle filter, a variable speed fan blower, and a filter housing that mounts two gas-particulate filter sets. The variable speed fan blower, managed by a motor control unit and motor speed algorithm, automatically adjusts its speed to maintain constant air flow regardless of its altitude.

A blower configured to be positioned in confined spaces and to provide ventilation of a fluid, such as temperature controlled air, is disclosed. In various embodiments, the blower is configured to have a reduced axial thickness, which can be desired in such confined spaces. In some embodiments, the blower has an integral filter, a wire channel for the routing of one or more wires, and/or an exposed backplate. In some embodiments, the blower has a snap-fit circuit board, containment system for mounting the motor, one or more vanes for directing fluid flow, shrouded impeller, and/or integrated connector.

Particular embodiments of the inventive technology may be described as an air handling shroud for establishment at the inlet area of a fan, the shroud adapted to realign and/or redistribute fan inlet flow so as to reduce fan-generated noise without unacceptably impairing fan efficiency and/or performance. Certain embodiments present a lattice arrangement of cells through which air flows; the shroud may protrude up from an inlet face lying in a plane defined by the fan (e.g., by the fan housing or an inlet cone). It may have a hemispherical shape and a lower resistance-per-area sector at the pole (or polar region) thereof. Optional componentry includes but is not limited to a flow obstructer established at a fan proximal portion of the shroud, and acoustic material established on surfaces of the cells of the shroud.

A heater side channel blower includes a blower housing (12) with a bottom wall (14) and a circumferential wall (16), that enclose a first flow chamber in a housing interior (18). A ring-shaped delivery duct (22), open towards an outer side of the blower housing (12), is provided at the bottom wall (14). A flow medium inlet (50), for the entry of medium to be delivered into the housing interior (18), is open towards the first flow chamber. A second flow chamber (42) is provided in the housing interior (18). A flow medium outlet (52), for the discharge of medium to be delivered from the housing interior (18), is open towards the delivery duct (22) to the second flow chamber (42). The first flow chamber is separated from the second flow chamber (42) by at least one chamber separation element (60, 62) that is permeable to medium to be delivered.

A compressor (1), or ventilator/anesthesia device with the compressor, includes a housing, a rotatable impeller (6) connected via a drive shaft (4) to an electric motor (5) to deliver gas from an inlet (8), upstream on a suction side (7) through a flow duct (11) to a downstream outlet (10) on a delivery side (9). The compressor impeller is partially enclosed by the housing, as a collection housing (2) on the delivery side, and a cover element (12), on the suction side separated in sections from the compressor impeller by a gap (13). An uncoupling element (15) is arranged, for vibration damping and for at least partial sealing of the housing interior against a surrounding area (16), between the cover element and the collection housing and between a functional component (14) connected at least indirectly to the compressor impeller and/or to the electric motor and the collection housing.