Abstract: An acoustic filter is provided with a single flow chamber for exposure of a flexible rubber layer to liquid undergoing flow through the flow chamber with noise producing acoustic energy therein. The flexible rubber layer is supported on a cylindrical drum with slanted holes therein through which the exposure to the liquid in the flow chamber is effected. An axially sectioned drum with dimensionally different diameters, radial thicknesses and slanted holes therein is positioned over the rubber layer within an outer casing to establish a plurality of gas-filled cavities of different axial lengths and separated from each other along the axial length of the liquid flow chamber which is connected at its opposite axial ends by pipe sections to a piping system from which the liquid within the flow chamber is derived.

Abstract: A muffler which reduces noises of a wide frequency band with a simple structure. Sound waves of an intake duct enter into and are received in a resonance box via a branch pipe. At the branch pipe, a movable body slidingly abuts a peripheral portion of an opening of a cut-out portion. Due to the movable body rotating, a range of opening/closing of the cut-out portion is changed, and a length of a neck portion formed by the branch pipe and an arc-shaped plate, and a lateral cross-sectional surface area of a distal end of the neck portion, are changed.

Abstract: An acoustic fluid machine such as an air compressor comprises an acoustic resonator, a valve device and a piston. Air is sucked into the resonator through the valve device at one end of the resonator. The piston at the other end of the resonator is reciprocated by an actuator to compress the air in the resonator to cause resonance to increase pressure of the air significantly. The inner surface of the resonator is suitably curved to comply with the formula of a half-period cosine function.

Abstract: An exhaust volume (20) of the type including a muffler (24) having a casing provided with an inlet (29) and an outlet (30) for passing gases and adapted to enable the muffler to be mounted in an exhaust system (14). The volume further includes an additional enclosure (26) forming an accumulation cavity communicating solely with the casing of the muffler (24) via at least one connection pipe (28), the additional enclosure (26) being placed outside the muffler (24). The additional enclosure (26) is of a structure whose ability to withstand high temperature is lower than that of the structure of the muffler (24).

Abstract: An air induction system for an engine to remove contaminants from intake air prior to delivery to the engine. The system includes an assembly for filtering air which is mounted in advance of the engine, and a duct for delivering air from the assembly to the engine. A sealing system is provided which prevents entry of unfiltered air while simultaneously permitting movement of the engine relative to adjacent parts of the airframe as engine power setting varies. The seal is protected from high pressures in the duct which can occur in operation of the engine.

Abstract: An in-line resonator for an air induction system of an internal combustion engine is provided. The system includes a resonator housing, an upstream duct, a downstream duct, a conduit, a partition, and a sleeve. The conduit extends through the resonator housing connecting the upstream duct and the downstream duct. The partition is moveable within the resonator housing and divides the housing into an upstream chamber and a downstream chamber. The downstream chamber, the conduit, and the downstream sleeve cooperate to form a first Helmholtz resonator that is in fluid communication with the downstream duct. The upstream chamber, the conduit, and the upstream sleeve cooperate to form a second Helmholtz resonator that is in fluid communication with the upstream duct. Further, a means is provided to axially move the partition to vary the volume of the chambers concurrently with the length and/or area of the passages.

Abstract: An HQ tube arrangement suitable for packaging within a vehicle may be designed by creating a mathematical model representing a tube arrangement having a first passageway and a second passageway fluidly connected to the first passageway at first and second junctions. The second passageway is divided by the junctions into first, second, and third passages. Lengths are associated with each of the first passageway and the first, second, and third passages. A filter parameter, based upon an average transmission loss for a particular frequency over a standard deviation, is analyzed as a function of the lengths. Lengths are chosen based upon analysis of the filter parameter. Portions of the outer walls of the first and second passageways may be secured to or common to one another so that lengths of the passageways run along side of each other to provide a more compact HQ tube arrangement.

Abstract: The invention relates to an exhaust silencer or muffler for an internal combustion engine, in particular a silencer with the damping characteristics of a resonator with the absorptive characteristics of a dissipative silencer. The silencer of the present invention provides an improved silencer or muffler for use with an internal combustion engine that incorporates both a dissipative silencer and a resonator in a single muffler assembly suitable for use with standard automotive construction techniques.

Abstract: In the engine muffler including a first expansion chamber 12 of the exhaust gas having an exhaust gas inlet aperture 11 connecting to an exhaust gas outlet of the engine, a second expansion chamber 14 having an exhaust gas outlet aperture 13, at least one first exhaust gas purifier 15 coated wit a catalyst to purify the exhaust gas purifier provided with innumerable numbers of small holes, a wall side of said second expansion chamber 14 to which the engine is not installed is formed to a double-wall construction of walls 14a and 14b with a predetermined distance, further, the double-wall is packed with a heat insulating material to improve the purification efficiency, heat insulation and sound elimination. Heated muffler wall is decreased. It is also possible by applying a detachable construction to take out the first exhaust gas purifier outside the wall for replacement or cleaning.

Abstract: A number of embodiments of acoustical devices for improving either or both the intake and exhaust sounds emanated from an internal combustion engine. This is achieved by employing acoustical devices which are configured so as to discharge the desired sound waves to the atmosphere rather than by attempting to dampen the undesired sound waves generated in the system.

Abstract: An exhaust processor includes a housing formed to include an interior region and a partition or first spark arrester that partitions the interior region into chambers and includes a wool filter formed to include an opening. The wool filter is positioned to filter unburned carbon particles from combustion product generated by a vehicle engine. The exhaust processor further includes an outer conduit that extends through the opening formed in the wool filter and is formed to include a passage and an inner conduit that extends into the passage and is formed to include an opening through which unburned carbon particles flow from inside the inner conduit to impinge against the outer conduit so that the outer and inner conduits operate as a second spark arrester.

Abstract: A muffler including an internal assembly formed of a pair of identical stampings. The internal assembly includes three tubes extending longitudinally between baffles. The internal assembly received within the muffler outer shell forms central upper and lower attenuation chambers as well as chambers at each proximal end of the muffler. The stampings are provided with impressions for forming weep holes and allowing acidic condensation to exit the central chambers. The stampings are located in mirror image relation with one another and are attached to one another by a rivet pattern and using the metal of the stampings. The rivets readily allow acidic condensate to flow between the upper and lower central chambers. Louver-shaped openings are provided on the stampings providing communication between the formed tubes and the upper and lower central chambers and thereby providing attenuation.

Abstract: A side branch resonator for attenuating sound waves of first and second frequencies, the side branch resonator comprising a discharge branch; a resonator branch; an inlet branch flow connected to the discharge branch having an axis, the resonator branch having a wall which defines a resonator branch interior; the resonator branch having an open resonator branch end and a closed resonator branch end; the resonator further comprising an attenuation member for attenuating the first frequency sound waves. The attenuation member is located in the resonator branch interior a first distance from the axis and upstream from the resonator branch closed end. The closed resonator branch end is located a second distance from the axis to provide attenuation of the second frequency sound waves.

Abstract: The present invention is a noise reduction apparatus for use in the exhaust system of an internal combustion engine which absorbs acoustical energy from the pressurized exhaust gases while minimizing restrictions on the exhaust gases as they flow therethrough. The relatively unrestricted exhaust gas flow provided by the present invention significantly reduces the build up of back pressure and the associated drop in power and performance of the engine. At the same time, by absorbing acoustical energy from the exhaust gases, the noise level of the exhaust system is reduced. The present noise reduction apparatus includes a housing operatively adapted for being disposed in the exhaust system of an internal combustion engine, and a plurality of sound absorbing layers disposed inside the housing. Each layer is operatively adapted to allow exhaust gases to flow therethrough while absorbing acoustical energy from exhaust gases coming in contact with the layer.

Abstract: An exhaust muffler includes upper and lower internal plates and upper and lower external shells. The internal plates are formed to define a chamber therebetween. The external shells are formed to define chambers on opposite respective sides of the interconnected internal plates. An upper tube plate is secured to the upper internal plate. The upper tube plate and the upper internal plate are formed to define an inlet tube therebetween. The inlet tube includes louvers to permit exhaust gas flow into the chamber between the upper internal plate and the upper external shell. Louvers in the upper internal plate permit exhaust gas to flow from the upper chamber into the internal chamber between the internal plates. Louvers in the lower internal plate permit exhaust gas to flow into the lower chamber. An outlet tube communicates with the gravitational low point in the lower external shell and permits flow of exhaust gas from the muffler while siphoning condensate in the lower chamber.

Abstract: An exhaust muffler includes a housing having a rectangularly shaped hollow interior without fiberglass or other packing. An inlet tube and a first outlet tube extend through one side wall of the housing, and a second outlet tube extends through an opposite side wall. The inlet tube extends to an inner end disposed at a central region of the interior in a position facing away from a forward end wall of the housing toward an opposite rearward end wall, while a baffle assembly within the interior includes perforated partitions that define two Helmholtz chambers, as well as a first passageway from the inner end of the inlet tube to the first outlet tube and a second passageway from the inner end of the inlet tube to the second outlet tube. The baffle assembly includes first and second plates disposed within the first and second passageways to split the flow of exhaust gases.

Abstract: A bumper/muffler assembly is provided to simultaneously perform noise attenuation functions and impact protection for an automotive vehicle. The bumper/muffler assembly is formed at least in part from stamped sheets of metal. The sheets include an internal plate formed with inlet and outlet channels therein. Inlet and outlet tube plates are secured to portions of the internal plate adjacent the inlet and outlet channels such that inlet and outlet tubes are defined. A front external shell is disposed in proximity to the rear end of the vehicle and is configured to be spaced from portions of the internal plate to define a front chamber. A rear external shell also is spaced from the internal plate to define a rear chamber. A plastic material may be nested over the rear external shell for aesthetic attractiveness of the assembly.

Abstract: A muffler for exhaust systems that feed exhaust into both ends of the muffler can. Exhaust gas enters into the muffler can where it enters an exhaust gas conduit that has a center plug installed. Exhaust is fed into both ends of the exhaust gas conduit. The exhaust gas is then forced out through a number of flared holes in the exhaust gas conduit, where it enters the muffler can and exits through an exhaust port. This design creates a longer exhaust flow path, which allows the exhaust gas to cool, extending the life of the muffler. Moreover, since the gasses are unimpeded in their flow through the conduit until they hit the partition plate, the exhaust conduit is less exposed to the full heat of the exhaust gas, unlike the cones, which do not penetrate deeply into the muffler can and bear the brunt of the exhaust gas.

Abstract: The present invention is a noise reduction apparatus for use in the exhaust system of an internal combustion engine which absorbs acoustical energy from the pressurized exhaust gases while minimizing restrictions on the exhaust gases as they flow therethrough. The relatively unrestricted exhaust gas flow provided by the present invention significantly reduces the build up of back pressure and the associated drop in power and performance of the engine. At the same time, by absorbing acoustical energy from the exhaust gases, the noise level of the exhaust system is reduced. The present noise reduction apparatus includes a housing operatively adapted for being disposed in the exhaust system of an internal combustion engine, and a plurality of generally concentric and radially spaced tubular sections disposed inside of the housing. Each tubular section is adapted with a porous wall which allows exhaust gases to flow therethrough. A plurality of sound absorbing layers are also disposed inside the housing.

Abstract: A stamp formed muffler includes a first plate, a second plate and at least one sheet. A second plate and the sheet are secured in face-to-face relationship with the first plate and define a plurality of tubes and an internal chamber. External shells are secured around the internal plates to enclose the tubes and the internal chamber. The external shell may be formed to engage the internal chamber such that the internal chamber divides the external shell into upstream and downstream chambers.

Abstract: A muffler is formed substantially from stamped components to include an array of flow tubes and a plurality of chambers communicating with selected flow tubes. The chambers are provided with siphon tube mounting grooves that extend between a plurality of the chambers. The grooves are disposed to lie at gravitational low points of the muffler. The muffler further includes a siphon tube closely engaged by the grooves and extending from the gravitational low points of the chambers into a downstream flow tube of the muffler. Pressure differentials in the flowing exhaust gas will cause condensate in the chambers to be sucked through the siphon tube and evacuated from the muffler.

Abstract: A muffler is provided for attenuating noise associated with flowing exhaust gas and for evacuating condensate from gravitational low points of the muffler. The muffler includes top and bottom plates that are formed to define a plurality of flow tubes therebetween. A bottom internal shell is secured to the bottom plate. The bottom plate and the bottom internal shell are formed respectively to define a siphon tube therebetween. The siphon tube includes a siphon inlet at a location that will coincide with a low point on the muffler and a siphon outlet in a selected flow tube. The muffler further includes a bottom external shell secured to the bottom internal plate and surrounding the bottom internal shell. Condensate accumulating of the gravitational low point of the bottom external shell will be drawn through the siphon tube and evacuated from the muffler.

Abstract: A resonator type silencer used in the air intake duct of an intake system of an internal combustion engine comprises a first case member which includes a generally cup-shaped section. A pipe section is integral with the cup-shaped section and extends through a bottom wall of the cup-shaped section. The pipe section has an inside portion located inside the cup-shaped section. An axially extending slit is formed in the inside portion of the pipe section. First and second flange portions are integral with the pipe section inside portion and located at opposite sides of the slit. The first and second flange portions are integral with the cup-shaped section bottom wall and located parallel with each other. The pipe section inside portion and the flange portions constitute an integral body having a first end face located near an open end of the cup-shaped section.

Abstract: A muffler including an offshoot path, one end of which is connected to a middle of a ventilation path so as to diverge from the ventilation path, and another end of which is closed. One portion of the offshoot path and another portion thereof are communicated through a communicating portion. Accordingly, sound waves entering the offshoot path are propagated in a direction of a closed portion, and are also propagated via the communicating portion from the one portion to the other portion.

Abstract: An improved aircraft muffler and the method of making it is disclosed. It is a plug muffler design having an outer housing and an internal exhaust conduit. The exhaust conduit has a center partition that blocks the flow of exhaust gas through the conduit. A number of holes are formed through the conduit wall such that the exhaust gas passes out through the holes on the inlet side of the partition and reenter the conduit on the outlet side of the partition. Unlike previous designs, the holes formed in the exhaust tube of the muffler are not flat and do not have hoods. Rather they have formed surfaces that slope. The formed surfaces both protrude above and below the exhaust tube wall. Thus the formed surface creates a directional flow path for the airflow to help increase the velocity, which consequently helps to move exhaust gases through the baffle as opposed to straight holes. The indented holes serve another purpose.

Abstract: The invention relates to a sound-damping arrangement in a passageway system or pipe system for flowing gases, in particular in an exhaust system for internal combustion engines. The arrangement comprising at least one pipe which communicates with at least two chambers or openings, for example in a form of a muffler and/or a passageway/pipe-outlet, in such a manner that multiples of standing waves can arise in the pipe between both the chambers or openings. At least one tube is arranged in the pipe, with one end of the tube serving as in inlet while the other end of the tube is totally or partially closed. The inlet of the tube is arranged in, or in the vicinity of, one of the maximum sound-pressure regions of the pipe so as to dampen at least one maximum sound pressure.

Abstract: A resonator type silencer installed in an intake system of an automotive internal combustion engine. The resonator type silencer comprises a generally cup-shaped base member integrally connected with an air duct through which intake air to be inducted into the engine passes. The air duct is formed with an opening through which the inside of the base member is in communication with the inside of the air duct. The base member is formed at its opened end with a peripheral flange. A cover member is formed at its opened end with a peripheral flange which is bonded to the peripheral flange of the base member to define a sealed chamber. A partition plate is fixedly disposed inside the sealed chamber to divide the sealed chamber into a first resonance chamber defined by the base member, and a second resonance chamber defined by the cover member.

Abstract: In general, sound resonators or mufflers are bulky self-contained metal bodies, which are expensive to produce and to install in an engine intake or exhaust system. A relatively simple substitute, which can be tailor made to attenuate sound at various frequencies include two arcuate casing sections which are interconnected along one side edge by a hinge, so that the sections can be wrapped around an engine air intake tube, a latch on the other side edges of the sections for securing the sections together to form a sleeve around and coaxial with the tube, an inlet nozzle on the interior of each section for extending into the tube, and partitions extending between the inner and outer surfaces of each section for defining elongated, tortuous, sound attenuating passages.

Abstract: A compact resonating muffler is disclosed. Specifically, the muffler is a part of a duct which is preferably rectilinear with an aspect ratio in the order of 3 to 1. The muffler contains at least two and preferably three or more rows or lines of Helmholtz type resonators placed on at least one side of the muffler housing. Preferably, the resonators are on opposite sides of the duct, these sides being opposite major sides when the duct is rectilinear. The first row of the resonators is tuned for attenuation of the major acoustical frequency to be muffled. The second row of the resonators is tuned to exclude the major damped frequency. Preferably, this row of resonators is tuned to harmonics of the major frequency. Finally, the third and last row of resonators is tuned again to muffle the primary frequency, this exact resonant frequency preferably being slightly different from the frequency of the first row of resonators.

Abstract: The invention relates to a rigidifying structure used to support half shells of a stamp-formed muffler by connecting at least one of the half shells to an inner plate disposed in the space between the half shells so that shell noise is minimized.

Abstract: Muffler assembly for an engine comprises an outer cylinder constituting a muffler body, an inner cylinder coaxially disposed in the outer cylinder, a connection cylinder disposed inside the inner cylinder having one end on an upstream side and another end on a downstream side, a partition plate disposed inside the inner cylinder at the downstream end of the connection cylinder, first and second silencer chambers formed at the upstream and the downstream end of the connection cylinder, respectively, an inlet, pipe through which an engine exhaust gas is introduced into the muffler body, and an outlet pipe having an upstream end disposed inside the inner cylinder and a downstream end opened outward of the muffler assembly. The connection cylinder has an upstream end portion in which a plurality of holes are circumferentially formed.

Abstract: A muffler for an air powered turbine drive includes a cone section made of perforated metal, a plurality of layers of sintered material on the inner surfaces of the cone section, an inner housing section substantially surrounding the cone section, an inner baffle wall between the inner housing section and the inner cone section, and an outer housing section substantially surrounding the inner housing section. Air entering the muffler through the cone section passes outwardly through the walls of the cone section and is then redirected several times before passing outwardly from the outer housing section in order to attenuate the noise in the air leaving the muffler without creating excessive muffler pressure.

Abstract: A muffler of the type used to attenuate exhaust gas noise in exhaust systems of automobiles, trucks, or the like, particularly characterized by a gas flow conduit which is axially slotted and laterally flattened to form a closure and a pair of openings axially inward of the closure, wherein the end walls of the shell are pressed into engagement with the conduit ends to close the conduit and support the conduit.

Abstract: An adjustable sound attenuating device comprised of an elongated outer main shell of a predetermined diameter, with an inlet coupling and an outlet coupling. The device has located within the shell singular or multiple independent baffle components comprised of a solid baffle plate, a perforated baffle plate, an optional perforated baffle plug, and several chambers provided by the baffle components. The solid and perforated baffle plates have a funnel shape to provide for smooth directional flow of exhaust gases. The perforated baffle plate is pierced with a plurality of openings to allow for the flow of the exhaust gases through the chambers. The perforated baffle tube is pierced with inwardly angled louvers spaced equally around the circumference and staggered to follow a spiral path lengthwise around the perimeter of the tube for routing gases through the chambers.

Abstract: An exhaust gas muffler comprises a double-walled casing having an inlet end receiving a stream of the exhaust gas and an outlet end for the exhaust gas, the outlet end comprising an outer tube surrounding a perforated inner tube spaced therefrom, and the tubes defining therebetween a perforation resonator chamber succeeded by a whistling sound resonator. The casing includes an outer wall and a corrugated inner wall defining a gap with the outer wall. A heat-resistant and sound-damping intermediate layer is arranged in the gap between the inner and outer walls and braces the inner wall against the outer wall. Transverse partitions divide the casing into a plurality of chambers between the inlet and outlet ends, and tubes connect the chambers and reverse the exhaust gas stream at least twice between the inlet and outlet ends.

Abstract: The invention relates to an air cleaner comprising a generally bell-shaped air cleaner housing and a generally frustoconical filter positioned concentrically within the housing. The housing has an air inlet at its small end and an air outlet at its large end for the flow of air generally axially into and out of the housing. The filter has a filter element coaxially juxtaposed the interior surface of the housing. The filter element is generally annular and has an upstream portion and a downstream portion. The downstream portion of a member supportably engages the upstream portion of the filter element. The upstream portion of the filter element has a diameter larger than the diameter of the member downstream portion. The member blocks the flow of air into the interior of the filter element and directs air axially along the exterior of the filter element. A downstream annular support piece engages the downstream end of the filter element.

Abstract: A muffler is constructed to have a tubular perforated plate within its cavity so as to divide the cavity into an outer resonant cavity and an inner resonant cavity, to thereby provide two resonant frequencies. The tubular perforated plate is formed in the shape of a funnel.

Abstract: A muffler assembly includes a pair of outer shells mating to define a muffler chamber and a pair of internal tuning plates mating to define inlet and outlet tubes in the muffler chamber. Drop-in baffles are used to divide the muffler chamber into an expansion chamber, a pair of exhaust turnaround chambers, and a pair of resonance chambers. The two outer shells and first tuning plates are mechanically locked together at the perimeter of the muffler assembly and the second tuning plate is piggybacked onto the first tuning plate to reduce the number of material layers included in the mechanical lock. Each of the outer shells includes one or more ribs and channels for stiffening the outer shell to reduce vibration noise and to conduct condensate developing in the muffler chamber either to a hotter region where it will vaporize or to a drain.

Abstract: A resonator used in an exhaust system of an automotive internal combustion engine. The resonator defines therein a resonance chamber and provided with an exhaust gas inlet tube through which exhaust gas is introduced into the resonator. An exhaust gas outlet tube is provided so that exhaust gas is discharged out of the resonator through the outlet tube. The inside ends of the inlet and outlet tubes are connected with a tuning tube respectively at positions which are opposite to each other with respect to the axis of the tuning tube. The opposite ends of the tuning tube are opened to the resonance chamber. The inner diameter of the tuning tube is larger than that of the inlet tube and that of the outlet tube, thereby greatly improving noise attenuating effects under resonance as compared with conventional resonators.

Abstract: A muffler comprising a casing, a defining member for defining at least two resonance chambers in the casing, and a pipe for flowing a gas therethrough. Each of the resonance chambers has a different resonance frequency, and the pipe is communicated with each resonance chamber. Therefore, a plurality of noise frequencies can be suppressed.

Abstract: A stamp formed muffler comprising a pair of internal plates and a pair of external shells is provided. The internal plates are stamp formed to define first and second spaced apart arrays of tubes and a single intermediate tube therebetween. Tubes in one array may have perforations or apertures to permit expansion of exhaust gases, while the other array may define at least one tuning tube. The tubes are disposed on the internal plates such that at at least one location thereon a straight line extending entirely across said internal plates will intersect only the one intermediate tube. The external shells are stamp formed to define a plurality of chambers which cooperate with the tubes in the internal plates. The chambers are separated from one another by a crease disposed to align with the intermediate tube. The crease is characterized by a single outwardly convex portion to engage the single bulb. As a result, the crease is not provided with recesses that conceivably could retain corrosive materials.

Abstract: A sound attenuation apparatus which is to be connected to an airflow duct and is to receive the air from the duct. The sound attenuation apparatus includes a mass of plates located in a stacked arrangement with peripheral gaps being formed between the plates. The airstream is to be conducted through an opening formed between the plates. The airstream is to be conducted into an opening formed within the center of the plates and then discharged into the ambient through the peripheral gap area. Each of the plates include a mass of holes.

Abstract: Two embodiments of outboard motors incorporating improved silencing systems for the exhaust gases of the powering engine. In each embodiment, a Helmholtz resonator is provided by a resonance chamber formed at least in part by a spacer plate that is interposed between the power head and drive shaft housing of the engine and which communicates with an expansion chamber of the engine through a tuning neck. In each embodiment, the effective volume of the resonance chamber of the Helmholtz resonator is varied in response to engine speed by delivering coolant to it from the engine cooling jacket and discharging the coolant at a restricted rate.

Abstract: A plug section for a muffler, including an outer body and having an inlet pipe for introducing exhaust gas into the body. The inner end of the inlet pipe located within the body portion is closed off. Surrounding the inlet pipe is a conical baffle having a small diameter end secured to the inlet pipe to provide a tapered chamber between the inlet pipe and the conical baffle, while the space between the conical baffle and the outer body defines an outer chamber. Both the inlet pipe and the conical baffle are provided with a plurality of perforations. Exhaust gas entering the inlet pipe flows outwardly through the perforations in the inlet pipe to the tapered inner chamber and then flows through the perforations in the conical baffle to the outer chamber. The use of the perforated conical baffle provides a substantial improvement in sound attenuation, reducing both the shell noise level and the outlet noise level.

Abstract: An outboard motor includes a cowling with a cavity that receives a carburetor that supplies the engine with an air/fuel mixture. The carburetor has an air intake port. An air intake passage connects to this port, and bends partway around the carburetor. A resonance chamber communicates with the air intake passage and faces the carburetor to attenuate the noise from the carburetor intake port.

Abstract: A fluidborne noise attenuator (14) comprises a dampening medium (27) which exhibits a bulk modulus (e.g., 50,000 psi to 180,000 psi) substantially greater than that of an inert gas, such as nitrogen, and substantially less than that of a hydraulic working fluid (e.g., 225,000 psi). The attenuator (14) is capable of attenuating noise levels of hydraulic fluid over wide frequency and mean system pressure ranges in contrast to conventional attenuators which are "tuned" for the attenuation of noise levels at a specific frequency and mean system pressure.

Abstract: The construction described is a resistive sheet type of duct liner or duct silencer; i.e., a liner or silencer in which acoustical flow resistance is concentrated in a thin face sheet separating the flow passage and acoustical cavity rather than in an acoustically absorptive packing material filling the acoustical cavity. The invention disclosed is means for applying inexpensive perforated facings, similar to those in a conventional packed silencer, to provide resistive sheets which are effective in terms of noise dissipation and in terms of self-noise (noise generated by flow through the flow passages).

Abstract: A sound absorbing structure for a flow duct composed of a bundle of parallel, terminated, acoustical waveguides. The bundle of waveguides is cut obliquely so that the individual waveguides vary substantially in length along the cut. The bundle is arranged within a structure which is revolvable about its longitudinal axis. The exterior surface of the structure is spaced from the interior wall of the duct. The longitudinal axis of each of the waveguides is located substantially perpendicular to the axis of revolution. The structure revolves during passage of gas through the duct.

Abstract: A sound absorber for intermittent exhaust gas, particularly for use in connection with a compressed air operated motor employed, for example, in a hand grinder. The sound absorber is arranged predominantly in the housing of the motor and includes an exhaust air discharging channel having an alternately varying cross-section to define a succession of continuously alternating narrow and wide passages for changing continuously the direction of flow of the exhaust air about an angle that is always lower than 90.degree. with respect to the axis of the discharge channel so that the ratio of successive minimum and maximum cross-sections of the channel is at most 4:1. The discharge channel is terminated with a nozzle plate defining a plurality of outlet nozzles the central axes of which converge in the direction of flow.

Abstract: A sound-attenuating muffler for reducing the acoustic energy in an exhaust gas stream has an elongated cylindrical housing with a small ratio of diameter to length. Axially extending vanes are radially disposed to define an added number of flow passages. Exhaust gas enters an entry passage defined between two vanes, travels past a side-branch resonator and terminates in the entry nozzle of a Helmholtz chamber. The flow turns through a port in one of the vanes and enters a reverse-flow passage, also defined between two vanes, flows past a side-branch resonator and is reversed again through a port through another vane. A third side-branch resonator is provided in the exit region. The muffler may comprise two or more separate similar muffler sections defining such serpentine gas flow paths, and the exit region of an upstream section may then be continuous with the entry region of a downstream section.