The present disclosure relates to an air vent structure. The air vent structure at least includes a tubular housing through which an air-conditioned air flows, and an annular finisher in an air flow-out end of the housing. The air vent structure further includes an air restrictor that restricts the inflow of the air-conditioned air into a clearance between the air flow-out end of the housing and the finisher.

A louver type blast valve making use of an aerodynamically configured blade, independently activated by air flow to block a blast shock wave and a subsequent return suction wave. The blast valve (FIG. 6) including a frame and at least one aerodynamically configured blade, independently activated by air flow to block a blast shock and a potentially following return wave. The aerodynamically configured blade having an elongated shape, including at least a steep convex surface and a flat or shallow concave surface, forming a leading edge and a trailing edge at the intersection of the surfaces. The blade being hinged to the frame about a longitudinal axis passing between the steep convex surface and the flat or shallow concave surface.

An acoustic system includes a duct that has a function of causing a fluid to flow therein and has a tubular shape, an internal sound source that is disposed inside the duct on an upstream side or at an outer peripheral portion of the duct, which communicates with an inside of the duct on the upstream side, or an external sound source that is on an outside from an end portion of the duct, and a membrane-shaped member that is formed as a part of a wall of the duct and vibrates in response to sound. A structure including the membrane-shaped member and a rear surface closed space thereof causes acoustic resonance to occur, transmits the acoustic resonance from the sound source into the duct, and suppresses sound radiated from the other end portion of the duct on a downstream side. The external sound source is at a distance within a wavelength at a frequency of the acoustic resonance on the outside from the end portion of the duct. In the acoustic system, as a small membrane-type resonance structure is disposed in a flow passage horizontal direction, wind does not directly hit a membrane surface perpendicularly, and since the acoustic system does not have a through hole or a hole, wind noise can be eliminated.

For example, an apparatus may include an input to receive input information including a Heating, Ventilation and Air Conditioning (HVAC) input including HVAC configuration information corresponding to a configuration of an operation of an HVAC system of a vehicle; a plurality of noise inputs representing acoustic noise at a plurality of noise sensing locations; and a plurality of residual-noise inputs representing acoustic residual-noise at a plurality of residual-noise sensing locations within at least one sound control zone in the vehicle; a controller configured to determine a sound control pattern to control sound within the at least one sound control zone in the vehicle, the controller configured to determine the sound control pattern based on the HVAC input, the plurality of noise inputs and the plurality of residual-noise inputs; and an output to output the sound control pattern to a plurality of acoustic transducers.

A heating, ventilation, and air conditioning (HVAC) system including a refrigerant line configured to carry refrigerant. A sound wave generator is in cooperation with the refrigerant line to introduce sound waves into the refrigerant line. The sound waves are configured to break up bubbles in the refrigerant within the refrigerant line to suppress noise resulting from the bubbles flowing through the HVAC system

An induction air handling apparatus and methods are disclosed. The induction air handling apparatus includes an air plenum extending along one end of an air mixing chamber and having a first wall forming a partition between the air plenum and the air mixing chamber, the air plenum being formed by extrusion, and having an air inlet disposed at one end thereof and numerous openings machined through the first wall. The induction air handling apparatus also includes air nozzles extending into the air mixing chamber, each nozzle having an inlet in fluid communication with the air plenum through a corresponding opening in the first wall of the air plenum, and an outlet opening into the air mixing chamber. The air nozzles are formed by machining and are rigidly connected to the first wall, to reduce audible noise when pressurized air passes through the air nozzles.

In some examples, an electronic device includes an audio output device, an airflow generator to generate an airflow, and a system controller to control an operational speed of the airflow generator. The electronic device further includes an audio controller to generate a noise cancellation audio output based on an indicator of the operational speed of the airflow generator provided from the system controller to the audio controller, and send the noise cancellation audio output to the audio output device to mitigate noise produced by the airflow generator.

A muffler comprising a hollow cavity enclosed by a first bottom surface, a second bottom surface and a side wall, the side wall connects the first bottom surface with the second bottom surface, an air inlet at one end of the hollow cavity and an air outlet at the other end of the hollow cavity; the cavity is divided into a plurality of chambers in an axial direction, the chambers comprise a first chamber adjacent to the first bottom surface, a second chamber adjacent to the second bottom surface and an intermediate chamber located between the first chamber and the second chamber, the air inlet is in gas communication with the intermediate chamber, and the air outlet is in gas communication with the first chamber.

A vertical humidifier with a stepped evaporator includes a housing. An evaporative water trough is provided inside the housing, and the stepped evaporator is provided in the evaporative water trough. A fan is mounted under the stepped evaporator, and an air inlet end of the fan is communicated with an air inlet of the housing. A water tank is further mounted at the upper portion of the evaporative water trough, the stepped evaporator is mounted around the lower portion of the water tank, and the water tank is further communicated with the evaporative water trough through a water inlet. An air outlet is provided at the upper portion of the housing, and the air outlet is communicated with an air outlet end of the fan. The stepped evaporator is arranged in an airflow channel between the air outlet and the air outlet end of the fan.

A method of forming a sound attenuator around a compressor of an air conditioning system includes providing a molding cover, positioning a compressor of an air conditioning system in a cavity of the molding cover, and placing a first material in the cavity of the molding cover. The method further includes placing a second material in contact with the first material in the cavity of the molding cover. The first material and the second material chemically react with each other to form a self-forming foam around the compressor.