Abstract: Provided are a soundproof structure and a soundproof unit that can be reduced in size and thickness in the soundproof structure using Helmholtz resonance. The soundproof structure that includes a housing forming a space therein and having a through hole that allows the space to communicate with an outside, and generates Helmholtz resonance by the space and the through hole, the soundproof structure includes a rear surface plate disposed at a position overlapping the through hole on the space side as viewed from a penetrating direction of the through hole, in which assuming that a diameter of the through hole is ? and a distance from the rear surface plate to an opening surface of the through hole on the space side is d, d?? is satisfied and d?6 mm is satisfied.

Abstract: This disclosure describes techniques for increasing wetting current for an electromechanical switch. In one example application, an aircraft may include one or more valves used to control the temperature of aircraft interior. The valves may include one or more valve position switches to indicate certain valve positions, e.g. fully open, fully closed, fifty percent open, and so on. In some examples, the valve position switches may receive current at electromechanical contacts of the switch that is less than the wetting current. The techniques of this disclosure provide additional wetting current at the time the switch contacts close to improve reliability of the valve position switches. In some examples, an analog to digital converter circuit may be configured to provide the additional wetting current to the switch.

Abstract: The invention relates to a diffusor having a wall (8) that encloses an inlet having a round cross-section that transitions into an angular cross-section on the outlet of the diffusor over the height of the wall (8) of the diffusor. The transitions (15) between the sides (34 to 37) of the wall (8) have a twist in the height direction that follows the twirl of the flow of air through the diffusor. The ventilator has such a diffusor. The device has a housing on which at least two ventilators, each having one diffusor, are arranged.

Abstract: A ventilation device comprises a body (11) having first and second ports (14, 15) and a ventilation passage (13) that extends through the body between the ports to allow airflow through the body. The ventilation device also comprises a noise attenuation device (21) arranged to attenuate noise transmission through the passage in at least one direction from the first to the second port. The noise attenuation device comprises at least one array (22, 23) of noise attenuation tubes disposed in the ventilation body. In one form, the noise attenuation device (21) include two arrays of attenuator tubes disposed on respective opposite sides of the passage (13). The tubes each have a mouth (27) that opens to the passage and a central axis that extends from the mouth in the direction of elongation of that tube.

Abstract: Silencing equipment provided with one or more flow channels through which cooling air flows has a flow channel forming member that forms the flow channel, and an acoustic absorbent member that is fixed to the flow channel forming member. A resonance type silencer is formed on a wall surface of the flow channel by providing a cavity for the resonance type silencer in the acoustic absorbent member and an aperture for the resonance type silencer in a portion of the flow channel forming member. The resonance type silencer sets a frequency of noise necessary to be reduced based on a peak frequency of noise generated by a fan. The silencing equipment further has a slide member which slides by a slide mechanism to adjust the area of the top of the aperture. The silencing equipment for electronic devices capable of cooling heat generating sections thereof with air has a small and simple structure and can improve a silencing effect by blowing air.

Abstract: A device for reducing sound from an air treatment unit includes, in one embodiment, an air treatment system, including a wall mount HVAC unit with a supply air opening and a return air opening. A supply air sound reducer is provided in communication with the supply air. The supply air sound reducer includes a housing defining a supply interior provided with sound reducing material. The sound reducing material is overlaid with a layer of perforated material. A return air sound reducer is provided in communication with the return air opening. The return air sound reducer includes a housing defining an interior return volume provided with sound reducing material applied to one or more inside surfaces of the interior return volume and a layer of perforated material disposed over the sound reducing material. Mid-structure including sound reducing material is disposed in each of the supply and return air assemblies.

Abstract: A sound attenuator for low frequencies in an air-conditioning duct of paper mills includes a sound attenuator frame insertable in the air-conditioning duct. At least one attenuator member operating according to the plate resonator principle has a first resonator plate, a framework, whereto the first resonator plate is attached by its inner surface, and a second plate, which is essentially parallel to the first resonator plate. The second plate is attached to the framework by its inner surface, whereby the second plate, the framework and the first resonator plate delimit at least one attenuator unit. The first resonator plate, attached to the framework, is a steel plate and is attached to the framework by laser welding and the framework comprises a pressure balancing opening.

Abstract: A damper is provided to suppress the abnormal noise or air noise at the small opening of the damper. The damper includes a wall surface which forms an air flow passage, a stationary portion which extends from the wall surface to the center of a flow passage, and a rotating portion rotatably disposed in the flow passage, having one end in contact with a portion of the stationary portion at a downstream side of an air flow through the flow passage. A curved wall portion as a convex curved surface protruding to the center of the flow passage is formed on a position of the wall surface on which the air flow passing between the one end and the stationary portion impinges.

Abstract: An air distribution system for an air conditioning system includes an air supply and a plurality of air distribution units. The air distribution units are arranged in a side-by-side configuration. The air supply is operably connected to at least one of the air distribution units. Each air distribution unit includes a delivery feature for delivering air from the air supply through the air distribution unit and into an adjacent air distribution unit.

Abstract: An air handling system adapted for mounting in a room of a building includes a double air inductor assembly having a first air inductor unit and a second air inductor unit adjacently arranged with the first air inductor unit. Each of the inductor units includes a plenum having a primary air inlet, a mixing chamber having a plurality of side surfaces with a return air inlet extending through one of the side surfaces and a supply air outlet extending through another of the sides, and a plurality of air nozzles that each span along a central axis between an inlet fluidly connected with the plenum and an outlet fluidly connected with the mixing chamber. The axes of the plurality of air nozzles of the first air inductor unit are arranged approximately parallel to the axes of the plurality of air nozzles of the second air inductor unit.

Abstract: A sound-baffling arrangement for use in conjunction with an air-handling unit. One or more sound baffle columns are mounted for rolling or sliding movement within the interior of the air handling unit housing. Each baffle column may be selectively moved between a use position proximate to the fan assemblies, and a non-use position more distal from the fan assemblies. The movable sound baffles permit the air-handling unit to be fabricated to fit within a smaller housing, and thus to have a smaller, more economical footprint.

Abstract: A vehicle heating, ventilation and air conditioning system includes a plurality of ducts for providing conditioned air to an interior of a vehicle. The plurality of ducts includes a window defrost duct and a floor duct. The system includes a mixing chamber upstream of the window defrost and floor duct. A damper is selectively controllable to distribute the conditioned air to one or more of the plurality of ducts. The damper is configured so that when in a floor only mode position, the damper directs conditioned air in the mixing chamber only to the floor duct. A bypass conduit is configured to direct air from the floor duct to the window defrost duct when the damper is in the floor-only mode position. The conditioned air directed through the bypass conduit attenuates noise generated in the mixing chamber from emanating to the window defrost duct.

Abstract: The invention relates to a noise-optimized ventilation system (100) which can in particular be integrated into a vehicle, with the ventilation system (100) having at least one heat exchanger (1) and a fan (2) for acting on an air guiding volume (3) with an air flow (7), wherein the air guiding volume (3) has at least one inlet (4), an outlet (5) and a sound barrier (6).

Abstract: A column air handling system includes a coil unit having a set of coils for changing a temperature of an air stream flowing therethrough and a fan unit for driving the air stream through the coil unit. The fan unit includes a plenum fan directly driven by a motor.

Abstract: A main body casing of a ventilator is formed with an outer airflow opening and an inner airflow opening and a ventilating path for connecting these airflow openings is formed in the main body casing. The ventilator ventilates a room and prevents entry of noise from outside into the room through the ventilating path. The ventilating path is bifurcated and these two ventilating paths have different lengths from each other so that a noise sound wave entering through one of the ventilating paths and a noise sound wave entering through the other ventilating path are out of phase with each other to cancel out each other's sound wave energy when the sound waves meet.

Abstract: A method and apparatus for reducing noise levels occurring at a particular frequency in an air distribution apparatus used with an automotive vehicle having an interior compartment. The apparatus includes a noise reduction structure located in the air duct between an inlet end connected to a housing and a discharge end located in the vehicle interior compartment. The noise reduction structure is located a position spaced between the housing and the interior compartment of the automotive vehicle. The particular position of the noise reduction structure is determined based on the frequency of the noise level sought to be reduced. The method includes measuring the frequency of the noise level emitted from the discharge end of the air duct and correspondingly positioning the noise reduction structure at a spacing or distance based on the measured frequency.

Abstract: An elevator cabin with an integrated ventilation system. A fan is attached to the elevator cabin and a vertical side wall of the elevator cabin has a plurality of distributed ventilation holes. At least one air channel element is attached to the side wall, so that the air channel element together with the adjacent portion of the side wall forms an air channel. An adapter element is situated between the fan and an inlet opening of the air channel for guiding air from the fan into the air channel so that the air travels from the fan through the adapter element into the air channel and through the ventilation holes into the elevator cabin.

Abstract: A displacement ventilation, low noise level, mixed air, HVAC system for ventilating a commercial or educational facility. The system includes a central HVAC air handling unit containing first and second duct works for receiving and transmitting conditioned air to rooms of the facility. Additionally, the system includes at least one air displacement terminal housing for delivering conditioned air to the room, where the air is delivered through an outlet in proximity to the floor of the room in a displacement manner.

Abstract: A low noise method and apparatus with the apparatus including a hood for mounting over an exhaust outlet duct to capture a fluid stream and then redirect the fluid stream to a fluid outlet in the hood through the use of smoothly curving duct that maintains the fluid flowing therethrough in a laminar flow condition with the inlet and outlet positioned such that there is no line of sight between the exhaust outlet duct and the fluid outlet duct in the hood.

Abstract: A muffler arrangement includes muffler elements arranged in rows which are oriented in each case transversely to a direction of flow. The muffler elements themselves are oriented in each case longitudinally in relation to the direction of flow. The distance between two adjacent muffler rows in this case amounts to approximately at least four times, or at least six times, the distance between two adjacent muffler elements of the equidistantly arranged muffler elements of a muffler row and/or the flow off edges of the muffler elements of at least one muffler row have guide plates. Equipping of the muffler elements of the last muffler row in the direction of flow may be dispensed with.

Abstract: Duct units for delivery of air to an air supply fan and for connecting this fan to an air heater unit are disclosed. The duct unit for delivering air in one version has a narrow first section, a second, transition-type section and a wide sound attenuating, third section with these three sections extending generally vertically. Spaced apart splitters containing sound attenuating material and having side walls of perforated metal are mounted in the third section. The splitters include a central splitter and outer splitters with the latter converging inwardly towards a central axis of the third section. This duct unit also has an elbow-shaped duct section connected to the third section at its upstream end and connectible to the fan at its downstream end. In another version, the duct unit has a single, elongate splitter that extends longitudinally along at least a major portion of a second duct section and that bends through a smooth curve.

Abstract: An aircraft engine run-up hangar comprises a building defining a test chamber capable of receiving an aircraft therein, an air inlet structure, and an exhaust structure. The air inlet structure is formed in a front end part of a roof structure corresponding to a front end part of the building, the exhaust structure is connected to a rear end part of the building and defines an exhaust passage extending obliquely upward from the back end of the building, and one or a plurality of current deflecting members are disposed near a lower end of the air inlet structure to deflect air currents flowing through the air inlet structure into the building toward an aircraft housed in the building. A current-straightening structure is incorporated into the air inlet structure. A current-straightening space is defined under the air inlet structure.

Abstract: An air handling apparatus for blending outside and return airflow including a housing having exterior side walls, a top and a bottom and containing first and second inlet regions and a mixing chamber. Outside air flows through a first inlet into the first inlet region while return air flows through another inlet into the second inlet region. There are also first and second damper mechanisms positioned between the first and second inlet regions and the mixing chamber, each capable of adjusting the amount of airflow from the respective inlet region to the mixing chamber. An exhaust fan is mounted on the housing above the second inlet region while an air supply fan is mounted in the housing on the downstream side of the mixing chamber. Heating and cooling coil units can be located downstream of the mixing chamber.

Abstract: An improved sound attenuating device for use in a gas transportation duct, said device comprising a core of acoustically absorptive material substantially enclosed within an impervious film to prevent direct contact between the acoustically absorptive material and gas flowing through said gas transportation duct, wherein said enclosed absorptive material is maintained in position between at least two perforated facing plates and further wherein there is provided between the perforated facing and the impervious film and between the impervious film and the acoustically absorptive material spacing means to allow unrestricted movement of the impervious film in the void between the perforated facing and the acoustically absorptive material, while preventing contact between the film and the perforated facing and between the film and the acoustically absorptive material, and blocking means to impede the internal flow of gas between the film and the perforated facing and between the film and the acoustically absorpti

Abstract: An aircraft engine run-up hangar comprises a building defining a test chamber capable of receiving an aircraft therein, an air inlet structure, and an exhaust structure. The air inlet structure is formed in a front end part of a roof structure corresponding to a front end part of the building, the exhaust structure is connected to a rear end part of the building and defines an exhaust passage extending obliquely upward from the back end of the building, and one or a plurality of current deflecting members are disposed near a lower end of the air inlet structure to deflect air currents flowing through the air inlet structure into the building toward an aircraft housed in the building. A current-straightening structure is incorporated into the air inlet structure. A current-straightening space is defined under the air inlet structure.

Abstract: The air mixer defined herein serves for static mixing of a heated air stream in a flow channel of a circulated air stream upstream of a heat treatment chamber for drying textile goods or tissue webs for example. For this purpose the air mixer is provided with air mixing parts that consist of hollow bodies arranged in the flow cross section of the first air stream with spaces between them, said bodies being provided to receive and conduct the second air stream with inlet openings and outlet nozzles located endwise on one side.

Abstract: A device for regulating the temperature in a room having an extraction vent and a delivery vent, using pulsed low-velocity air flow (qs). A pipe is provided in communication with a pressurized air supply duct via extraction and delivery orifices, and the extraction vent and the delivery vent open out into the pipe. Two coaxial air streams are formed in the pipe between the extraction and delivery orifices, and a central stream is produced in which the air moves at a high velocity and a peripheral annular air stream is formed surrounding the central air stream in which the air moves at low velocity.

Abstract: Audio noise created by trim valves (66a-72a) in a warm air trim system (24) of an air cycle air conditioning system (10) is reduced by controlling the pressure drop across the trim valves as a function of the position of the valves (66a-72a). A proportional valve (112) typically under the control of an electronic controller (116) is controlled to set the pressure drop across the trim valves. Reducing the pressure drop across the trim valves, reduces the noise created by air flowing through the trim valves thereby reducing noise in an aircraft cabin.

Abstract: A room air conditioner in which a blower housing is formed of a foamed insulation material. The foamed insulation material is formed in three separate pieces with each of the pieces fitting together to form a single structural unit forming the blower housing and wall portions of two separate air conduits. The pieces are configured and apertured to fit snugly together and to provide various passages for diverse components of the air conditioner.