Abstract: An intake combustion resonator including an enclosure which includes a resonator tube assembly passing through the enclosure. The resonator tube is formed from porous, undulated tube material and has openings formed in the tube walls. The openings serve as “tuned” passages through the porous tube walls. The resonator tube assembly is not centrally located within the enclosure but rather it is offset both in a height and a width orientation. The size, spacing, and orientation of the tube openings, porous, undulated sleeve material, the design of the enclosure, and the placement of the tube within the enclosure, all act in concert to give rise to the noise abatement properties of the present invention.

Abstract: A muffler for quieting the operation of a pneumatic tool. In one embodiment the muffler (630) is disposed within a volume defined by a peripheral wall (612) that receives an exhaust stream. An upper plate (631) having several open tubes (632) is disposed in the volume. Each tube is has an intermediate blocking plate (634). A plurality of sound-deadening panels (636) is disposed below the upper plate. The panels have apertures that slidably engage the tubes. A lower plate (650) is disposed below the tubes. The lower plate includes a plurality of apertures (657). One or more diffuser panels (652, 654) is disposed beneath the lower plate. An external exhaust vent (670) closes the volume. In operation, the exhaust enters the volume, is directed through the tubes, then into the sound-deadening panels, back into the tubes, and through the diffuser panels.

Abstract: An air cleaner and resonator assembly is formed from a lower shell portion and an upper shell portion that are joined together to define an interior cavity having an inlet through which air is drawn. An exit tube, formed within the lower shell portion, directs air from the inlet to the engine. A middle shell portion is positioned within the inter cavity and is joined to both the upper and lower shell portions. A lower portion of a resonator is molded into the lower shell portion and an upper portion of the resonator assembly is molded into the middle shell portion. The upper portion is aligned with the lower portion and the middle and lower shell portions are welded together to form a sealed resonator chamber that attenuates engine noise. The upper and lower shell portions are then welded together to form the air cleaner and resonator assembly. Air filters are installed within the interior cavity and are selectively accessible through movable covers installed in the upper shell portion.

Abstract: A vessel having a drain port having a shape improved for preventing formation of water film to the drain port can be provided without making large a diameter of the drain port. In a sectional plane including a center line 6 of the drain port 5, one 7 of wall section constituting the drain port is inclined with respect to another one 8 of wall sections thereof. Accordingly, water can smoothly drops down by its gravity without forming any water film due to surface tension. Furthermore, since the formation of the water film can be prevented without making large a diameter of the drain port, invasion of the water inside the vessel from the outside of the drain port 5 can be also prevented.

Abstract: A suction system for an internal-combustion engine is provided with at least one container, which can be connected by way of feed pipes with the intake ports of a cylinder head. Openings of the intake ports for charge cycle control are monitored by valves. In the container or in the feed pipes, at least one reflection chamber is provided, which is connected with the interior volume of the container by way of a hole structure. The hole structure is formed by a plurality of openings that are formed in a wall section of the container, and are closed off by a cover fastened to the exterior side of the container wall, providing a reflection chamber which reduces noise in the suction system without adversely affecting air flow in the interior of the suction system.

Abstract: An intake combustion resonator including an enclosure which includes a resonator tube assembly passing through the enclosure. The resonator tube is formed from porous, undulated tube material and has openings formed in the tube walls. The openings serve as “tuned” passages through the porous tube walls. The resonator tube assembly is not centrally located within the enclosure but rather it is offset both in a height and a width orientation. The size, spacing, and orientation of the tube openings, porous, undulated sleeve material, the design of the enclosure, and the placement of the tube within the enclosure, all act in concert to give rise to the noise abatement properties of the present invention.

Abstract: An engine intake resonator and manufacturing method is provided by a pair of molded sheets mated to each other along a plane and defining a plurality of tubular channels therebetween and having different length for attenuation of different frequencies.

Abstract: The present invention relates to a vehicle's air intake device. In an embodiment, the intake device comprises an intake pipe, an air cleaner case in fluid communication with the intake pipe, a connection pipe in fluid communication with the air cleaner case, a carburetor attached to the connection pipe, and a plurality of resonators. In an embodiment, the intake device comprises an intake pipe, an air cleaner case in fluid communication with the intake pipe, a connection pipe in fluid communication with the air cleaner case, a carburetor attached to the connection pipe, and means for reducing intake sound levels.

Abstract: A continuously variable Helmholtz resonator for a vehicle air intake system having a vibratory input to the resonator wall to dynamically adjust the cancellation frequency for time-varying acoustical signals, and at least one of mean resonator volume control, mean resonator neck length control, and mean resonator neck diameter control whereby control of both the dynamic and the mean properties of the resonator provides a wide-tuning spectrum and facilitates canceling of time-varying acoustical signals.

Abstract: The suction muffler of a reciprocating compressor according to the disclosed invention comprises a flow controller for controlling the flow of refrigerant so that a steady amount of refrigerant flows into the suction port of the suction muffler. The flow controller comprises a fixing member having a main refrigerant path, a plurality of refrigerant sub-paths formed to vertically penetrate the fixing member along and adjacent to a circumference of the main refrigerant path at predetermined intervals, and a space with a diameter larger than an imaginary circle made by connecting the plurality of refrigerant sub-paths, formed under the main refrigerant path and the plurality of refrigerant sub-paths. A movable member has a first through hole formed to correspond to the main refrigerant path, and a plurality of second through holes formed at predetermined intervals on the imaginary circumference having a diameter larger than an imaginary circle made by connecting the plurality of refrigerant sub-paths.

Abstract: A silencer for connection to the air intake of a machine such as a turbocharger compressor. The silencer comprises a housing containing a plurality of axially spaced annular noise attenuating baffles. Each baffle has an outer circumference and an inner circumference defining a central aperture, the central apertures of each baffle collectively defining an axial outlet flow passage to an outlet aperture. The baffles define a series of axially spaced generally annular partial flow passages such that air flowing through the silencer is initially split and then merges into the axial outlet passage. Each of the annular flow passages curves radially inwards from its outer to its inner circumference in a direction towards the axial. Additionally, or alternatively, the dimensions of the annular partial flow passages vary so that the velocity of air flow through the passages is greater for passages closer to the axial outlet aperture.

Abstract: A sound attenuation system for a compressor of a direct fuel injected engine of an outboard motor comprises a discharge sound attenuator connected in fluid communication with an air distribution manifold outlet and a suction sound attenuator connected in fluid communication with the suction port of a compressor. In a typical application of the present invention, the air distribution manifold is connected in fluid communication with a discharge port of the compressor. Both the discharge sound attenuator and the suction sound attenuator can further include filter media disposed within their internal cavities.

Abstract: The present invention relates to a gas flow-through line with a sound absorption effect. Thereby the wall (5) of the line (1) has through-going perforations (2) having a diameter of less than 1 mm. The invention can for example find employment in the air suction hoses of a turbocharger of an internal combustion engine.

Abstract: An air intake system for intake air of an internal combustion engine comprising a filter insert (19) in a housing (10) connected to the air conducting system by a plurality of inlets (13) and an outlet (22). The air inlets are provided with individual intake nozzles or fittings and lead to a single common air chamber (20) in the filter housing. The inlets (13) can be individually opened and closed by flap valves (24), thereby allowing the acoustics to be influenced favorably and enabling, for example, the respective intake fittings to be connected or disconnected depending on the temperature. The intake system requires only a limited number of components, and the design of the preferably wedge-shaped air chamber minimizes flow losses in the housing, which in turn decreases the intake noise. Shunt resonators (28) can also be formed using cover elements (29) and (30).

Abstract: A variable tuned telescoping resonator which militates against the emission of noise energy caused by intake air in a vehicle wherein the connector length and the volume of the resonator are varied as a function of engine speed simultaneously to provide attenuation of noise energy over a wide frequency range.

Abstract: A suction muffler in a reciprocating compressor is installed over a suction valve to attenuate complex sound pressure (noise) such as vibrational noise, valve sonance, flowing noise and pulsative noise produced from the suction valve when low temperature, low pressure refrigerant gas ejected from an evaporator is sucked into a cylinder via the suction valve and a suction portion of the cylinder. A Tesla valve having two distribution paths is mounted in the suction muffler to attenuate the complex sound pressure (noise) while preventing the reflow of the refrigerant gas into the suction muffler from the suction valve. As a result, the Tesla valve also enhances the cooling ability of the compressor and the attenuation effect.

Abstract: The invention concerns an intake manifold (1) comprising a plenum (8) and air ducts (13) one of which at least, for each combustion chamber of the engine, has a sudden enlargement (19) of its passage cross-section, immediately followed in downstream direction by a duct portion (20) having a gradually decreasing cross-section and ending (21) upstream of a flange fixing (16) the manifold (1) to the engine and its cylinder head. The plenum (8) and each of the air ducts (13) at least are made of synthetic material, preferably capable of being molded. The invention is useful for equipping internal combustion engine with pistons driven in reciprocating movement in the cylinders.

Abstract: A closed motor-driven compressor includes a compression component (2) and an electric component (3) for driving the compression component (2), both of which are elastically supported within a closed vessel (1). A suction muffler (8) is mounted on the compression component (2) and includes a plurality of elements (10, 11, 12; 14, 15, 16; 18, 19, 20; 22, 23, 24; 26, 27, 28) assembled together and each made of synthetic resin. One of the plurality of elements (10, 11, 12; 14, 15, 16; 18, 19, 20; 22, 23, 24; 26, 27, 28) has a guide rib (13; 17; 21) integrally formed therewith that is tapered down toward an adjoining one of the plurality of elements (10, 11, 12; 14, 15, 16; 18, 19, 20; 22, 23, 24; 26, 27, 28), thereby facilitating assembly of the two elements.

Abstract: A multi-chamber resonator box for a vehicle air intake system, wherein the resonator includes a Helmholtz, an expansion chamber, an annular, and a perforated style resonator to militate against the emission of noise energy caused by intake air.

Abstract: A muffler is provided for use in a pneumatic hand tool having a handle with an exhaust passage. The muffler includes an inner tube, an outer tube, an upper plate, and an end cap. The inner tube is located within the outer tube, with one or more openings being provided in each. The upper plate is located near the inner tube and is provided to close off the exhaust passage so that a majority of the exhaust air is directed into the inner tube during use. The end cap attaches to the handle for closing off the exhaust passage, but for one or more exit openings. During use, exhaust air enters the inner tube, flows out its penguins, flows out the outer tube openings, and flows out the exit opening in the end cap. The tortuous path slows the exhaust air and assists in dampening exhaust noise.

Abstract: A fan shroud includes a fan shroud portion having a surface including an aperture. A cooling fan is supported proximate to the aperture for permitting air flow through the fan shroud from the environment to the engine compartment. An air intake portion is supported on the fan shroud portion. The air intake portion and the fan shroud portion together define at least a portion of an air passageway having an inlet for receiving ambient air and an outlet for connection to an engine throttle. The fan shroud portion and air intake portion may respectively include first and second circumferential portions that define the air passageway.

Abstract: The invention is a device for muffling the sound of escaping gas from a dispensing pipe for natural gas or any similar gaseous fuel, where the dispensing pipe has one or more first orifices. The device is an insert that may be placed into the dispensing pipe. The insert has second orifices through which the natural gas or any similar gaseous fuel escapes, and the second orifices are smaller than the first orifices.

Abstract: An apparatus for damping acoustic vibrations in a combustor as well as a corresponding combustor arrangement with the apparatus. The apparatus includes a Helmholtz resonator (4) that can be connected via a connecting channel (2) with a combustor (1). The Helmholtz resonator (4) contains a hollow body (6) the volume of which can be changed by adding or draining a fluid via a supply line (5), or is located adjacent to such a hollow body in such a way that the resonance volume (3) of the Helmholtz resonator (4) is changed when the volume of the hollow body (6) is changed. This apparatus makes it possible to adjust the resonance frequency of a Helmholtz resonator arranged inside a pressure container in accordance with the respective current operating point of the combustor to be damped, without having to pass movable components through the pressure container.

Abstract: The object of the invention is to provide an apparatus for noise depreciating in hermetic compressors. In the apparatus for noise depreciating for hermetic compressors of this invention, a diaphragm (45) is mounted to the interior surface of a chamber cover (40) through a welding process, thus dividing the interior of a muffling unit (30) into two chambers (31 and 31′). In a process of producing the above device, the chamber cover (40), integrated with the diaphragm (45), is locked to the top of a frame (2) having the chamber (31), with a packing (35) being interposed along the junction between the cover (40) and the frame (2). In the device of this invention, an inclined part (47) is formed along the edge of the diaphragm (45), thus allowing the diaphragm (45) to be easily and firmly integrated with the chamber cover (40) into a single structure by a welded material C during a process of welding the diaphragm (45) to the chamber cover (40).

Abstract: A side-branch resonator which has a resonator chamber connected to an air intake pipe with two necks. The necks extend into the resonator chamber and provide a conduit for sound to travel to and from the air intake pipe. The presence of two necks increases the magnitude of attenuation at the resonant frequency and the bandwidth of attenuation of other lower frequency engine noises. The two necks also effectively attenuate higher frequencies by utilizing standing waves found within the resonator chamber.

Abstract: A sound suppression system for suppressing the noise of an engine within an enclosure of an outdoor unit for a transport refrigeration system. A resonator is provided to suppress noise caused by the inflow of air to the air intake manifold of the engine, and a sound panel is provided in the bottom wall of the enclosure to suppress noise emanating from the engine. The resonator and the sound panel are co-located in the same plane and are preferably integrally formed of a molded plastic material.

Abstract: To dampen a sound created in an electrical tool or appliance having an air passage through which air is being forced, a sound damper is placed in the air passage. Preferably, a filter is provided upstream of the sound damper to prevent suspended particles, fibers, fumes and the like from entering the sound damper.

Abstract: The present invention provides an acoustic filter having a structure that does not affect upon the characteristics of an acoustic filter. This acoustic filter is equipped with a filter case having an air pressure inlet, a filter cap having an air pressure outlet, and a ring-shaped packing component attached to the air pressure outlet. A welding conjunction structure is employed between the filter case and the filter cap.

Abstract: A suction muffler for a compressor employed in a home appliance having a refrigeration cycle reduces noise produced by the compressor. The suction muffler includes a muffler body and a refrigerant suction pipe. The muffler body defines a resonance chamber and is coupled to a refrigerant supply pipe. The refrigerant suction pipe connects the resonance chamber to a compressor cylinder. The refrigerant suction pipe has at least one hole formed in its cylindrical wall. The muffler further includes a guiding portion in the resonance chamber to direct refrigerant from the supply pipe to the at least one hole in the refrigerant suction pipe and to direct noise exiting an upper end of the refrigerant suction pipe away from the refrigerant supply pipe. The suction muffler shortens the refrigerant flow path and lengthens the noise transmission path, thereby reducing the level of noise emitted while increasing efficiency of the compressor.

Abstract: Disclosed is a suction muffler including a muffler inlet, a muffler outlet communicating with the muffler inlet, a plurality of reservoirs defined between the muffler inlet and the muffler outlet, a plurality of small-diameter tubes adapted to allow the reservoirs to communicate sequentially with one another, and a vibration absorbing member installed on an inner wall surface of each of the reservoirs at a region where a flow of fluid sucked at a high velocity into the muffler inlet and forced to flow to the muffler outlet via the small-diameter tubes is struck against the inner wall surface, the vibration absorbing member serving to absorb vibrations generated due to pulsations of the fluid flow resulting from the striking of the fluid flow against the inner wall surface, thereby attenuating flow noises resulting from the vibrations. This suction muffler obtains an effect capable of offsetting noises generated when refrigerant gas flows are struck against inner constructions of the suction muffler.

Abstract: An arrangement for reducing noise produced by an engine idle air bypass valve and passage includes positioning an acoustic diverter at the end of the air bypass passage to force the noise away from exterior surfaces of a downstream chamber and toward the internal cavities of the engine such as a cylinder head. The diverter of the present invention reduces noise without causing restriction of air flow through the air bypass passage.

Abstract: A suction muffler for a hermetic sealed reciprocating compressor which comprises (i) a muffling chamber having a body of a synthetic polymeric material and (ii) a synthetic polymeric perforated tube passing through the muffling chamber carrying refrigerant fluid from the suction tube of the compressor to the suction port on the valve plate of a cylinder in which a piston reciprocates. The muffling tube may be made divergent along at least 10% of its length. The muffler is mounted directly in the cylinder head by means of a tongue and slot formation avoiding the need for a suction plenum between the suction muffler and the valve plate inlet.

Abstract: The hollow body of an intake silencer comprises a pair of matching insert (42,44) of rigid moulded plastics material which are confined in a lower-cup shaped element (28) by a lid (30) and which together have a T-shaped configuration with a longitudinal partition (46) which corresponds to the leg of the T and which extends in the lower element (28) dividing it into two juxtaposes resonance chambers (88, 90), and with a transverse partition (48-56) which corresponds to the transverse portion of the T and which separated the juxtaposed resonance chambers (88, 90) from an upper outlet chamber (96). Each insert (42, 44) comprises a respective upper flange (48, 56) corresponding to a respective half of the transverse partition.

Abstract: A duct or conduit section (10) for installation, in particular, in an air intake system of an internal combustion engine, in which the duct section is composed of two shells (14) which are joined by a snap connection (15). Openings located in the parting seam or joint (16) between the shells (14) are produced by recesses in the half shells. These openings each have a cross-sectional area of less than 7 mm2 and are useful for suppressing noise resulting from the air intake. As a result of the openings, vibration-inducing forces exerted on adjacent components in the engine compartment due to pulsations in the intake tube, can be minimized or avoided. Also, the quantity of additional air drawn in from the engine compartment, which is undesired because it is too warm, is decreased.

Abstract: An enclosure for an air aspirating machine, such as a compressor 11 for a fuel cell drive 13, which represents a closed volume, so that said volume can be used acoustically for the air that is being drawn in. An air intake 17 is extended into the enclosure 12, which is made of a sound damping and absorbing material 18, so that the resonant cavity 19 acts as a series resonator. The air is drawn in via an air inlet 21 of the compressor 11. Alternatively, the resonant cavity can also be used as a parallel resonator in that the intake path for the air is sealed within the enclosure 12 and is provided only with sound communicating openings to the resonant cavity.

Abstract: The invention concerns a suction muffler for a hermetically enclosed compressor with a housing that has at least a first and a second chamber, separated from each other by means of a division wall and connected with each other by means of a throttling channel, which is designed to allow flow from the first to the second chamber.

Abstract: An induction system employed in an engine of a small watercraft includes the first intake chamber communicating with the combustion chambers within the engine and a second intake chamber communicating with the first intake chamber. At least one auxiliary air aperture is provided in the first intake chamber so as to allow an auxiliary flow of air into the first intake chamber during, for example, sudden acceleration.

Abstract: A device for reducing sound emitted by the air intake of a internal combustion engine is provided. The device includes a dampening chamber formed of a one piece construction by rotational molding. Included as part of this mold are two tubular pipe-like sections designating both an inlet and an outlet whereby air is directed into the engine through the inlet and sound emitted by the engine is dampened as it enters the outlet of the silencer. The inlet and outlet are each formed within a pocket constructed in the mold that assists in creating the flow path for air as it moves throughout the chamber. The arrangement of the inlet and outlet in relation to one another assists in defining the sound reduction capability of the instant design and construction.

Abstract: A continuous partition wall is formed in the air introducing duct. The air introducing duct has a length L. The partition wall has a length equal to or greater than L/2. The partition wall divides the air introducing duct into first and second sections. A resonance silencer and a connecting duct are connected to the first section. A connecting position of the resonance silencer and the connecting duct is set such that the connecting position is fully included within a partition wall positioned range. A valve is arranged in the second section. Thus, intake noises is decreased in a wide range from a low frequency about 40 Hz to an intermediate frequency about several hundred Hz, which is normally hearable.

Abstract: Disclosed is a muffler in which a helicoil member is installed in each conduit, through which refrigerant gas flows from or into an expansion chamber during reciprocating movements of a piston in a cylinder. The helicoil member has diverse twisted angles and diverse twisted shapes, and serves to divide pulsation of noise, generated during the reciprocating movements of the piston, into pulsation of different phases, and then to merge the divided pulsation together, while allowing the refrigerant gas to have the form of a vortex flow. As pulsation of noise generated during an operation of sucking refrigerant gas pass along different travel paths defined by the helicoil member, a mutual interference occurs between the pulsation respectively emerging from the travel paths of the helicoil member. Therefore, an increased offset effect for the pulsation of noise is obtained, which maximizes a noise attenuation effect.

Abstract: A method for manufacturing intake mufflers, particularly for compression circuits for refrigeration systems and the like, comprising the steps of: molding a cover and a base of an intake muffler; and mutually assembling the base and the cover in a mold inside which a perimetric profile is formed which is adapted to form a retention joint which is molded perimetrically at the edge where the base and the cover are mutually coupled.

Abstract: A sound-absorbing duct structure for an intake system of an automotive internal combustion engine. The sound-absorbing duct structure comprises a duct defining thereinside a gas passage. A part of the duct is formed with a plurality of small holes. An expanded duct section is formed around the part of the duct. The expanded duct section defines therein an inside space which is in communication with the gas passage through the small holes. The inside space has a cross-sectional area larger than that of the gas passage. A sound-absorbing section is disposed in at least a part of the inside space of the first expanded duct section. The sound absorbing section includes a piezoelectric material exhibiting a piezoelectric effect, and an electrically conductive material in contact with the piezoelectric material.

Abstract: A muffler assembly for muffling noises associated with a compressor. The muffler assembly is mounted on the compressor such that the two move as a solid body. The muffler assembly includes an intake having a hollow interior adapted to receive a first flow of gas from the ambient environment. A baffle disposed in the hollow interior of the intake restricts the flow of gas through the intake. In one embodiment, the baffle defines at least a portion of a plurality of fluid portals that separate the first flow of gas into a plurality of flows of gas as the gas passes from a first side of the baffle to a second side of the baffle. As a result, the first flow of gas is disturbed and noise from the compressor is thereby attenuated. In another embodiment, a plurality of baffles are disposed in the hollow interior of the intake to define a tortuous path for the flow of gas through the intake for attenuating noise.

Abstract: An air induction device (11) for an internal combustion engine including an air filter housing (12) with an open induction tube (13) leading away from it and a supplementary induction tube (14) having a closing element, preferably in the area of its end opening (15). The closing element may take the form of a rotary flap (17) and is actuated depending on engine speed. The housing (12) and the induction tubes (13, 14) are configured in geometrical terms in such a way that at low engine rotational speeds, the housing (12) and the open induction tube (13) form a Helmholtz resonator, while the closed supplementary induction tube (14) forms a quarter-wave tube leading from the housing (12). At higher engine rotational speeds, the supplementary induction tube (14) is opened, and the overall length of the supplementary induction tube (14) is adapted so that at the higher speeds, it forms a Helmholtz resonator with the air filter housing (12) and the open induction tube (13).

Abstract: There is provided a baffle plate of a discharge muffler for a hermetic reciprocating compressor which is mounted in an inner portion of the discharge muffler mounted at a lower portion of a cylinder block so as to reduce flow noise of a refrigerant discharged to a discharge pipe, characterized in that an extended duct, which is communicated from a center portion of the baffle plate to the discharge pipe and has a diameter, is formed during a press molding. The extended duct is formed to be directed to the cover from the baffle plate by a burring process during a press molding, thereby improving the noise excluding efficiency.

Abstract: A muffler assembly for muffling noises associated with a compressor. The muffler assembly is mounted on the compressor such that the two move as a solid body. The muffler assembly includes an intake having a hollow interior adapted to receive a first flow of gas from the ambient environment. A baffle disposed in the hollow interior of the intake restricts the flow of gas through the intake. In one embodiment, the baffle defines at least a portion of a plurality of fluid portals that separate the first flow of gas into a plurality of flows of gas as the gas passes from a first side of the baffle to a second side of the baffle. As a result, the first flow of gas is disturbed and noise from the compressor is thereby attenuated. In another embodiment, a plurality of baffles are disposed in the hollow interior of the intake to define a tortuous path for the flow of gas through the intake for attenuating noise.

Abstract: An intake manifold including a collector defining an intake bore through which an air flow passes, and a noise reducer connected with the collector. The noise reducer includes a base wall mounted to the collector and formed with an aperture substantially aligned with the intake bore, and a cover wall extending over at least a portion of a circumferential inner surface of the wall to reduce noise generated within the intake bore.

Abstract: The present invention relates to an apparatus for damping acoustic vibrations in a combustor as well as a corresponding combustor arrangement with the apparatus. The apparatus comprises a Helmholtz resonator (4) that can be connected via a connecting channel (2) with a combustor (1). The Helmholtz resonator (4) contains a hollow body (6) the volume of which can be changed by adding or draining a fluid via a supply line (5), or is located adjacent to such a hollow body in such a way that the resonance volume (3) of the Helmholtz resonator (4) is changed when the volume of the hollow body (6) is changed. This apparatus makes it possible to adjust the resonance frequency of a Helmholtz resonator arranged inside a pressure container in accordance with the respective current operating point of the combustor to be damped, without having to pass movable components through the pressure container.

Abstract: An air intake muffler for a heater, especially a motor vehicle heater, with a hollow body (7) of sound-absorbing material which is surrounded by a muffler chamber (2) and is penetrated by a cavity (8) which is flush with an inlet connection (9) and an outlet (10) of the muffler chamber (2) which can be connected to an air intake opening of the heater. To reliably prevent water or moisture from penetrating into an assembly downstream of the muffler (1), it is provided that the muffler chamber (2) is downstream of a water separator which has a water separation chamber (3) with at least one air intake opening (20 to 23) in its wall located laterally offset relative to the inlet of the muffler chamber (2) and which is separated from the muffler chamber by a deflector wall (24 to 27) which prevents direct flow from the air intake opening to the inlet connection (9).

Abstract: A snorkel duct including a main body portion extended forwardly from an air cleaner in an oblique upper direction with a substantially uniform cross sectional area and a bent portion bending at a front end portion thereof. An air inlet is provided at a front end of the bent portion and is opened at a position where water, dust or the like is difficult to invade. A main opening portion opened in a lower direction is provided at a portion of the main body portion at a vicinity of the bent portion and a smaller drain hole is opened on a lower side thereof An expansion chamber is attached to a side of the main body portion in order to cover the main opening portion and the drain hole, and the cross sectional area of the main body portion is rapidly enlarged at the main opening portion to thereby reduce air-flow resistance, prevent pulsation sounds from being generated, and to silence intake noise.