A fan, such as an axial, radial, or diagonal fan, includes a fan impeller and an outlet guide device located in a housing/flow channel downstream of the fan impeller. The outlet guide device may include outlet guide blades that, when viewed in the spanwise direction or radial direction, extend over only a portion of the flow area.

A centrifugal blower for HVACR applications includes a squirrel cage forward-curved blower fan and a scroll housing. The blower fan comprises a plurality of blades that are configured to emit air radially outward and tangentially from between the blades when the blower fan rotates at a first speed. The air so emitted has a deviation angle defined as the difference between the direction of the emitted air and the blade exit angle. The scroll housing has a spline-shaped wall that has an axial cross-section that is configured such that the deviation angle of the air emitted from the blower fan at an axial plane deviates by no more than fifteen percent circumferentially about the blower fan in-between the spline-shaped wall and the blower fan and such that the average tangential velocity of air between the spline-shaped wall and the blower fan deviates by no more than thirty percent.

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 noise-lowering structure includes a fan frame and a connection section. The fan frame has a bottom side and a circumferential wall. The circumferential wall defines an airflow passage. Two ends of the airflow passage respectively have an inlet and an outlet. The connection section is disposed on inner side or outer side of the circumferential wall. The connection section has an internal passage. Two ends of the internal passage respectively have an inlet end and an outlet end. The outlet end is disposed on the inner side of the circumferential wall in connection with the airflow passage near the inlet. The inlet end is disposed on the bottom side in flush with the outlet. The connection section serves to guide the high-pressure air at the outlet to jet to the inlet so as to achieve multiple noise-lowering effects.

An axial flow fan includes an axial flow impeller, a motor configured to drive the axial flow impeller to rotate, and a resistance member. The axial flow impeller includes a hub having a shaft hole and blades arranged at an outer peripheral wall of the hub. The motor includes a motor body and a motor shaft connected to the motor body and engaged in the shaft hole. The resistance member is arranged at the hub and close to a free end of the motor shaft. A stiffness of the resistance member is greater than a stiffness of the hub.

A noise reduction method of a ventilator, comprising the following steps: S1 starting a ventilator and imputing a required wind pressure d at a man-machine interface, and then sending a signal to an actuator through a processor, and adjusting a first blade automatically to a maximum adjustable angle state a′° through the actuator and a second blade to a minimum adjustable angle state b°; S2 regulating a revolution speed, when a wind pressure is d, feeding back a revolution speed c, a conducting noise e.sub.1 and a radiated noise f.sub.1 to the processor through an acquisition device, and after the processor receives a revolution speed information, sending a command to lock the revolution speed to the actuator through the processor. The present disclosure can effectively solve the poor noise reduction function of the present noise reduction hoop, and can effectively reduce the cost and simplify the installation process.

The respiratory blowing device is provided with a first unit including a first housing and a second unit including a rotating body and a second housing. The first housing includes a first outlet, the rotating body includes a first coupling port and a first coupling path, and the second housing includes a first inlet and a second outlet. The rotating body is configured to rotate between a first position and a second position. At the first position, the first outlet is coupled to the first coupling port in a state that the first housing and the second housing are separated from each other. At the second position, the first housing is attached to the second housing by the rotation of the first housing to approach the second housing in a state that the first outlet is coupled to the first coupling port.

A cross flow fan includes a fan frame and a rotor having a hub, a shaft connected with the hub at its rotation center, a plurality of blades, and a disk structure connected with the blades and hub within the fan frame. The fan frame has a frame wall having a lateral flow inlet to the rotor and a lateral flow outlet from the rotor, a base carrying the rotor and frame wall, a cover on one side of the frame wall opposite to the base, and a partition structure disposed between the blades and an inner wall surface of the frame wall. A normal line of the lateral flow inlet and a normal line of the lateral flow outlet are not parallel to an extension direction of the shaft. The blades directly face the lateral flow inlet and the lateral flow outlet along radial directions of the shaft.

Airflow from a blower fan can be adjusted between a cooling air mode where cooling air flows freely to the ambient surroundings and a noise mode where the airflow is partially or fully restricted in order to produce different levels of soothing background noise. The airflow from the fan can be split or divided between varying degrees and combinations of unrestricted airflow, partially restricted airflow and fully restricted airflow to produce a wide range of cooling airflows into the ambient with or without the production of additional background noise. A perforated drum surrounds the fan to form a chamber within which airflow can resonate at various frequencies and amplify noise levels selected by rotating the drum around the fan.

The invention relates to a housing (1) for a fluid machine, in particular for a radial fan (2), comprising at least one housing part (3), wherein the housing part (3) has at least one inlet opening (7), wherein the housing part (3) can at least partially delimit a fluid chamber (8) for receiving at least one fan wheel (9), and wherein the inlet opening (7), at least in part, has a curved inlet surface (11). To produce a housing (1) for a fluid machine, in particular a housing (1) for a radial fan, preferably for use in a car seat and offering reduced noise emission together with good performance, the curved inlet surface (11) has at least in part the form of a logarithmic spiral in cross-section, and/or at least one guide element (21) extends from the inlet surface (11) towards a central axis of the inlet opening (7), and/or on the inside (17) of the housing part (3) there is provided a circumferential recess (25) which at least partially circumferentially surrounds the inlet opening (7) and/or a circumferential projection (6) which at least partially surrounds the inlet opening.