Abstract: The invention is directed to an exhaust gas muffler for a two-cycle engine, especially for a handheld portable tool, such as a chain saw. In exhaust gas mufflers equipped with a catalyzer, the formation of flame from the fuel-containing exhaust gases exiting from the muffler must be prevented. These exhaust gases are intensely overheated because of the exothermal process in the catalyzer. The muffler according to the invention includes a catalyzer which establishes a connection between separate component chambers of the muffler housing. The muffler can be mounted directly on the motor outlet.

Abstract: A muffler for impeding and reflecting exhaust to reduce the formation of sound waves through a plurality of cone and barrier assemblies alternately and longitudinally spaced in a cylindrical body, with the apex of a conical member of each cone assembly and an outwardly extending cylindrical portion of each barrier assembly being directed towards the input end of the body. Exhaust flow paths for dissipating exhaust noise are defined by orifices formed in the conical members and cylindrical portions, and spaces between spokes joining each conical member to a circular member.

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 flat, box-like muffler formed of metal upper and lower housing sections and internal gas passage defining plates has drainage holes to allow liquid that collects on the top of the muffler or on the bottom of the lower section inside the housing to drain out of the muffler. A special sound attenuation structure comprising passages pressed in the plates and support channels in the housing sections is shown.

Abstract: A stamp formed muffler is provided with a nonplanar array of tubes. The tubes are defined by at least one pair of nested formed members. The nested members include at least one external shell having a nonplanar portion and at least one internal plate having a nonplanar portion, with the respective nonplanar portions being configured to be placed in generally nested face-to-face relationship. The nonplanar configuration comprises an array of channels, such that an array of tubes is defined by the channels when the components are placed in nested relationship to one another. One or more chambers of the muffler are defined adjacent the nested formed members. The chambers may be defined by a single plate placed in register with the nested components or by a second pair of nested members. The nested pairs of formed members is effective in dampening shell noise attributable to vibration of the formed members.

Abstract: A kit includes a self-contained muffler which attaches to the output exhaust system of a small two-cycle engine, such as a model engine that is in the range of 0.15 to 1.25 cubic inches displacement. The kit provides a low cost adaptation of existing engine manifolds to meet required sound reduction guidelines of below 90 Db at nine feed from the engine. The kit is easily adapted and installed on a wide variety of manifold-muffler adaptations, for example model engines using a mounting bolt which clamps the kit muffler to a portion of the existing engine muffler.

Abstract: An exhaust muffler for an internal combustion engine, comprising a hollow casing defining a plurality of chambers which are communicated with each other by way of small holes, an exhaust inlet tube fixedly attached to an exhaust port of an internal combustion engine at its one end and fitted into the casing from a hole provided therein for communication with one of the chambers at its other end, and an exhaust outlet passage communicating another one of the chambers to the atmosphere. The internal end of the exhaust inlet tube and an opposing casing wall are joined by a threaded fastener while the exhaust inlet tube is provided with an annular shoulder surface which fits into the hole of the casing in an air tight fashion, so that the mounting of the muffler can be accomplished simply by fitting the casing of the muffler onto the exhaust inlet tube which is typically attached to a cylinder head of an internal combustion engine in advance and tightening the threaded fastener.

Abstract: The invention is directed to a compact noise abatement muffler for an internal combustion engine. The muffler includes a housing having a plurality of chambers and fluid conductors for enabling the exhaust gases passing through the muffler to achieve at least 4 changes of direction of gas flow. The muffler of the invention is capable of reducing the sound pressure level of the exhaust gases between the input and exhaust ports of the muffler in the range of 10-25 decibels.

Abstract: The silencer according to the invention contains two chambers (10,11) separated by a partition wall (14) and includes also a guide plate (25) guiding cooling air from a fan (27) through a channel (26) in which recesses (23) from one chamber terminate. By means of an ejecting function, then being formed, exhaust gases are evacuated into the channel and mixed with the cooling air to a lower temperature.

Abstract: A sound attenuating muffler for motor vehicle exhaust systems contains a fibrous glass cartridge with a binder-hardened outer shell surrounding a soft fibrous core through which a gas flow tube extends.

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 stamp formed exhaust muffler for mounting on a vehicle is provided. The muffler comprises a plurality of plates secured in juxtaposed relationship and stamp formed to define an array of tubes therebetween. At least one external shell is secured to the internal plates to define at least one chamber which communicates with the array of tubes. The external shell includes a conformal area which permits the muffler to conform to the shape of a structure on the vehicle. The conformal area may be an area of generally arcuate concavity when viewed from the exterior of the muffler or may define an internal corner on the muffler. Thus, a plane or line connecting two locations on the conformal area of the external shell will pass through the interference zone of a structure on the vehicle.

Abstract: A compact, sound-attenuating muffler for an internal combustion engine is disclosed in which the muffler includes a stream dividing partition positioned proximate the inlet of the muffler to divide the incoming exhaust gases into two streams of substantially equal volume. The stream dividing partition directs the streams laterally of the inlet in directions diverging from each other, and the muffler sound-attenuating assembly further includes corridor defining partitions receiving the streams from the stream dividing partition and maintaining the streams in corridors as coherent substantially eddy-free streams. The corridor defining partitions further direct the streams laterally to converge towards each other for discharge of the coherent streams against each other from opposed directions in a common volume inside the muffler casing. Further sound attenuation is accomplished by a common channel receiving the streams after they are intersected or discharged against each other.

Abstract: Disclosed herein is an inner exhaust gas housing adapted to be located within a drive shaft housing of an outboard motor, which inner exhaust gas housing integrally includes an open upper end, a first exhaust passage extending downwardly from the upper end, a second exhaust passage extending downwardly from the upper end, an expression chamber adjacent the upper end, a first passage communicating between the first and second exhaust passages and the expansion chamber, and a second passage communicating with the expansion chamber and with the atmosphere exterior to the inner exhaust gas housing.

Abstract: A suction type road sweeping vehicle utilizes a suction fan for generating a vacuum within an air tight container mounted on the chassis. Suction conduits extend at one end into the container and are provided at the other end with nozzles. A sound attenuation system connected to an outlet duct of the fan comprises an expansion duct inside which is mounted a perforated panel connected to an attenuation duct, whose outlet exhausts to the atmosphere. Air expelled from the fan passes into the expansion duct, through the perforated panel which acts to raise the frequency of the sound of the air and through the attenuated duct, which has a noise absorbing lining which absorbs the sound as the air passes through the duct before being exhausted to atmosphere. Thus, the noise emitted by such road sweepers which, by the very nature of their construction and operation, are noisy vehicles, may be substantially reduced without hindering the flow of discharged air.

Abstract: A muffler is provided with a pair of internal plates stamp formed to define an array of tubes therebetween. An external shell, which may be stamp formed, surrounds and encloses at least selected portions of the internal plates. The array of tubes stamp formed in the internal plates includes at least two tuning tubes. One tuning tube terminates at a tuning aperture in one of the two internal plates, while the other tuning tube terminates at an aperture stamp formed in the other of the two internal plates. Thus, one tuning tube will communicate with a low frequency resonating chamber on one side of the pair of internal plates, while the other tuning tube will communicate with a low frequency resonating chamber on the opposite side of the assembled internal plates.

Abstract: Noise suppression and particle separation apparatus for flows of high pressure, high velocity, particle-laden, gaseous fluid, such as geothermal steam, comprises a gaseous fluid conduit that has axially installed around its discharge end a larger diameter, cylindrical inner expansion chamber having a number of flow-dividing fluid discharge openings at which fluid flow diffusing elements are connected for receiving and diffusing the flow of gaseous fluid from the apertures. A still-larger diameter, cylindrical noise suppression chamber is axially mounted around the inner chamber and flow diffusing elements. The diffusion elements increase the fluid flow noise frequency range and sound deadening material installed in the outer chamber absorbs noise in this higher frequency range so that the venting fluid noise level outside the apparatus is no more than about 95 dB.

Abstract: An exhaust muffler is provided. The muffler may be formed from a pair of internal plates that are secured in registration with one another and are formed to define an array of tubes through which the exhaust gages may travel. Selected portions of the tubes in the internal plates may be formed to include perforations. The muffler may further include at least one external shell formed to define at least one chamber which may at least partly surround the perforations in the internal plates. At least one inlet or outlet may lie on the seam between the formed plate members. However, at least one inlet or outlet may also be provided through a portion of the muffler spaced from the seams. The inlet and/or the outlet may be angularly aligned to the longitudinal axis of the muffler and may further be angularly aligned to one another.

Abstract: A muffler is provided including a pair of internal plates formed to define an array of tubes. At least one external shell is formed to define at least one chamber which will surround and enclose a selected portion of the array of tubes. Selected portions of certain tubes will be formed to include perforations. Portions of certain tubes will further undergo cross-sectional changes to control the flow of exhaust gases through the muffler. Certain channels between adjacent chambers of the external shell will be disposed to extend substantially continuously from peripheral portions of the adjacent chambers formed in the external shell. In certain embodiments, a controlled communication is provided between a low frequency resonating chamber and an adjacent expansion chamber. In other embodiments, additional formed layers are provided to enhance either heat or noise insulation.

Abstract: A suction sound damper for a slide piston refrigerant compressor that includes a suction nipple that is pushable into a groove of a cylinder cover of the compressor when the nipple is in a predetermined position, and is seatable in sockets formed in two shells of a damper housing. The shells are sealed together after the nipple is seated in the sockets. The suction nipple is of a material having a higher thermal resistance than the shell material. The damper includes intermediate walls that together with the shells form four somewhat triangular chambers with a throttle opening from the first chamber to the second chamber, an elongated throttle passage from the second chamber to third chamber and a throttle opening from the third chamber to the fourth chamber. The suction nipple opens to the first chamber and each shell includes a part of an inlet that opens to the fourth chamber.

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: A silencer-carrying rotary vane pump wherein a hollow portion is provided between inner and outer circumferential walls of a cylindrical center case of the vane pump. The hollow portion is closed with side covers to form a sealed chamber through which a pumped out medium is discharged to the outside. A plurality of partitions may be provided in a portion of the sealed chamber to divide the sealed chamber into a plurality of sealed compartments, with adjacent compartments being in communication with each other by a passage having a small cross-sectional area. Soundproof members may be provided in the sealed compartments and an additional discharge port may be provided for communicating the sealed chamber with the outside of the pump.

Abstract: A muffler is provided with a pair of stamp formed internal plates and a pair of stamp formed external shells. The internal plates define inlet and outlet tubes at least portions of which are provided with arrays of perforations or louvers. One or more tuning tubes may be stamp formed in the internal plates and one or more low frequency resonator chambers may be stamp formed from portions of either the internal plates or the external shells. The external shells may further be configured to define high frequency tuning chambers of a selected size and shape.

Abstract: A retroverted flow type exhaust gas muffler has curved flow directing and guiding plates mounted on end headers to facilitate flow reversal.

Abstract: The muffler comprises a main sound arresting chamber formed in the interior of an outer cylinder of the muffler and a bracket fixedly secured to the outer surface of the outer cylinder for mounting the muffler on a body of a motorcycle. The muffler is provided with an auxiliary sound arresting chamber formed in the interior of the bracket and communicating with the main sound arresting chamber through a connecting passage so as to increase the total volume of the sound arresting chamber, thereby permitting the output of the engine of the motorcycle to be enhanced while the sound arresting effect on the exhaust gas is improved. The main sound arresting chamber may be divided into an upstream side main sound arresting chamber portion and downstream side main sound arresting chamber portions by partition means and the auxiliary sound arresting chamber portion communicates with the upstream main sound arresting chamber portion. The connecting passage may be in the form of a plurality of small diameter holes.

Abstract: An exhaust silencer for internal combustion engines, particularly as used on motor vehicles including tractors. A front pipe, a plurality of core tubes and a tail pipe have successive inner flow channels of equal section areas. The plurality of core tubes are integrally connected to the larger end of a trumpet pipe. The walls of the core tubes are punched with flanged holes forming converging passages. Flow-dividing plates are provided in the tail pipe. The exhaust flow divides into smaller substreams on passing through the front pipe and the core tubes, thus raising the ratio of expansion, leading to a decrease in noise level and exhaust back pressure, while reducing engine output loss. The noise level of a vehicle can be reduced to 80-83 dB(A), while oil consumption is reduced by 6-8.8%.

Abstract: Disclosed is a simple steam trap muffler. It is comprised of two comentric pipes which are both welded at their first ends to the exhaust pipe of a steam trap. The steam and condensate flows into the inner pipe from the exhaust pipe. The inner pipe has its opposite end capped so that the steam and condensate can not flow to the atmosphere through this inner pipe. However, the inner pipe does have orifices in its circumferential side through which this fluid can flow into the annular space between the first and second concentric pipes. There is no cap on the second end of the outer pipe. Thus the fluid flows along this annular space and out of the muffler through this open end of the outer pipe.

Abstract: A muffler for exhaust gases of an internal combustion engine. The muffler is a hybrid consisting of gas expansion chambers defined by partitions in a muffler casing, and a sound-absorbing body. The sound-absorbing body includes a perforated pipe surrounded by a porous sound-absorbing material with a thin metal film sandwiched therebetween.

Abstract: A muffler is provided with a pair of stamp formed internal plates and a pair of stamp formed external shells. The internal plates define inlet and outlet tubes at least portions of which are provided with arrays of perforations or louvers. One or more tuning tubes may be stamp formed in the internal plates and one or more low frequency resonator chambers may be stamp formed from portions of either the internal plates or the external shells. The external shells may further be configured to define high frequency tuning chambers of a selected size and shape.

Abstract: A catalytic converter has a gas pervious catalyst support member extending across a housing and dividing the housing into an upper chamber and a lower chamber. The catalyst support member has two parallel spaced apart upper and lower foraminous sheets which undulate across the width of the container and each having a single peak and a single trough to form a catalyst containing chamber between the two sheets having a generally sinusoidal-type wave configuration when viewed in cross-section along a plane perpendicular to the length of the housing. A bed of catalyst particles substantially fills the catalyst containing chamber. A gas inlet at one end of the housing is positioned to cause gases to enter into one of the upper and lower chambers and pass through the catalyst support member and the catalyst containing chamber to the other of the upper and lower chambers, with a gas outlet at an opposite end of the housing being positioned to cause the gases to leave from the other chamber.

Abstract: The invention is a venturi of unusual configuration and a method and apparatus for forming such a venturi in a single operation from a rounded, deformable tube. According to the invention, diametrically opposing sides of the tube are inwardly deflected in increasing amounts from opposing ends of the tube so as to form along the length of the tube from either end a first chamber of increasingly flattened and reduced cross-section followed by a second chamber of decreasingly flattened and reduced cross-section. An elongated throat section of maximally flattened and reduced cross-section may be provided between the first and second chambers, particularly for engine muffler venturis. The tube is conveniently deformed by applying pressure to a pair of its opposing sides along at least a portion of its length, preferably by pairs of opposing dies or eccentric rollers. Venturis for engine mufflers are conveniently fabricated from thin walled steel tubes by cold forming the tubes in the manner described.

Abstract: A basic new method and devices for treating flowing substances such as subdivided solids, colloids, gels, liquids and gases, under varying temperatures, pressure and velocity conditions is disclosed. The method is characterized by forming three concentric types of non-turbulent and unobstructed streams flowing essentially in one direction but differing in velocity from one another, the outermost of which is accelerated to become a surrounding jetstream flowing tangentially past reduced openings interconnecting with the other two types of streams, reducing fluid pressure in them until suction-effect at origin point results, and by final recombination of flows to produce a helically spinning accelerated vortical exiting thrust, to insure either virtually silent atmospheric gaseous discharge or energy-efficient pumping and optimally frictionless travel of liquids or flowing solids through extended conduit, for which devices are supplied by this invention.

Abstract: A high performance vehicular muffler is provided. The muffler includes a centrally disposed outlet tube, an inlet tube and a transfer tube. Internal baffles define a low frequency tuning chamber with which the inlet tube and transfer tube communicate. A high frequency tuning chamber surrounds the portion of the outlet tube between the internal baffles. The high frequency tuning chamber is packed with an absorbant. The opposed end caps of the muffler are provided with outwardly bowed portions to achieve a more laminar flow of exhaust gases and to minimize back pressure.

Abstract: A vacuum cleaner apparatus having separate passages for outgoing air from the blower and for cooling air for the blower motor, and having a number of turns in each of said passages, each of said passages having a plurality of variations in cross-sectional area, the passages being provided with sound-absorbent linings.

Abstract: An exhaust passage has an upstream end connected to an engine combustion chamber and a downstream end open to the atmosphere. A device substantially equalizes natural frequencies of the exhaust passage respectively corresponding to third-degree and fourth-degree modes of standing pressure waves developing in the exhaust passage. A pressure damper is connected to a point of the exhaust passage at which an antinode of the third-degree or fourth-degree mode lies.

Abstract: An axially asymmetric exhaust gas muffler has a perforated central exhaust duct that is circumscribed by a duality of reactive sound attenuating chambers in each of which is positioned a resonant sound attenuator.

Abstract: An exhaust gas silencing assembly or unit of the wet-type receives the exhaust gases from a water cooled internal combustion engine used to power a water-going vehicle, such as a speed boat, and the coolant water from the water jacket of the engine. The exhaust gas and water mixture may be expelled through a downwardly directed combined exhaust gas and water outlet of the silencing unit, or in response to opening a valve in an exhaust flow tube of the unit, exhaust gases and some of the water may be expelled directly out an outlet opening of the silencing unit. When the water and exhaust gases are expelled downwardly into the turbulent waters and foam of the wake of the boat the level of sound emanating from the silencing unit is substantially minimized. Upon opening of the valve at an outlet end of the silencing unit to provide straight through fluid flow the sound level of the engine is at a maximum, but the back pressure imposed on an engine is at a minimum for providing maximum engine performance.

Abstract: A muffler for use on an internal combustion engine includes an enclosure generally cylindrical and having end plates for closing the internal volume of the enclosure, at least one partition plate for dividing the internal volume of the enclosure into at least two chambers, an inlet tube, supported by one of said end plates and at least one partition plate, for conducting combustion gases supplied from the engine to one of the chambers; an outlet tube, supported by the other of the end plates and at least one partition plate, for blowing out the gases from remaining one of the chambers; and a connecting tube supported by said at least one partition plate for interconnecting the volume of adjacent ones of the chambers. At least two of the inlet, outlet and connecting tubes are integrally made of a single sheet of metal shaped to form a combination tube including the at least two tubes. A method of manufacturing such a combination tube is also provided.

Abstract: A noise converter according to this invention is provided with gas conducting spiral passages defined between spirally twisted outer and inner tubes polygonal in cross-section. A gaseous body generating noise flows through the gas conducting passages from one end to the other. Since noise is generated by masses of particles of gaseous body having energy, particles of less energy move forward along a course near the center of each spiral passage whereas those of more energy along the other course near the outside of the passage due to centrifugal force, thereby dispersion and attenuation of energy being performed.

Abstract: The present invention is directed to muffler apparatus and a method for making same. The apparatus includes inlet and outlet tubes with a plurality of baffles extending from the inlet and outlet tubes to a housing. The outlet tube has a constricted portion near its inlet end formed with creases and lobes and a flare at the end. Such constriction increases the housing to outlet tube area ratio of the muffler which results in advantageous attenuation characteristics. The process for making the muffler is simpler than known methods since the outlet tube is formed and baffles pressed onto it in a single step.

Abstract: A silencing system for exhaust gases from internal combustion engines, comprising an intermediate silencing device for connection to the exhaust manifold of an internal combustion engine, and a final silencing device series connected to the intermediate silencing device, in which the final silencing device comprises, within an envelope, a number of spaced annular members, intersected by radial partition walls, forming series of chambers of different size, which occupy the peripheral portion of the envelope and open towards the axial portion of this latter, leaving this axial portion substantially free for passage of the flow of exhaust gases, and an idle fan is provided for acting onto the passage for the exhaust gases and onto a passage for additional air, which passages join downstream the fan into an exhaust nosepiece. Some annular members are made of a catalytically active material in order to exert a purifying action on the exhaust gases.

Abstract: A muffler for exhaust gases of an internal combustion engine. The muffler is a hybrid consisting of gas expansion chambers defined by partitions in a muffler casing, and a sound-absorbing body. The sound-absorbing body includes a perforated pipe surrounded by a porous sound-absorbing material with a thin metal film sandwiched therebetween.

Abstract: A silencer for a pneumatically operated hydraulic jack equipped with an air motor is provided. The silencer comprises a first low-pressure chamber formed contiguously to the rear wall of the main cylinder of the air motor, a second low-pressure chamber formed contiguously to and behind the first low-pressure chamber, a baffleplate partitioning the first and second low-pressure chambers and having two groups of first holes formed at an angular displacement of 90 degrees from a pair of discharge holes formed diametrically opposite to each other and radially so as to discharge high-pressure air from the main cylinder of the air motor into the first low-pressure-chamber, and two groups of second holes formed at an angular displacement of 90 degrees from the two groups of the first holes respectively in the rear wall of the second low-pressure chamber to discharge air into the atmosphere.

Abstract: A muffler of the absorption type for the exhaust gas of an internal combustion engine including a cylindrical porous sound-absorbing body 1, and a film 5 of the metal or other material formed cylindrically on the inner surface of the porous body 1. The film prevents clogging of the pores in the porous body and enables the absorption of the sound in a wide frequency range.

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 muffler for large high r.p.m. internal combustion diesel engine in which the structure cancels sound waves by interference. The gases generally flow in one direction through the muffler with intermittant flow reversal occurring only upon acceleration. The muffler is formed with a plurality of longitudinal chambers divided by reflection walls. Edge echo openings in the reflection wall permit limited gas entry into the chambers. A plurality of helical members surrounded by a large open tube and pierced by a small open tube channel a substantial portion of all of the gases through a bulkhead wall which divides the muffler housing into two large open chambers and a smaller percentage of gases flows through one or more large open tubes.

Abstract: A muffler for large internal combustion diesel engines in which the structure cancels sound waves by interference. The gases generally flow in one direction through the muffler with intermittant flow reversal occurring only upon acceleration. The muffler is formed with a plurality of longitudinal chambers divided by reflection walls. Edge echo openings in the reflection walls permit limited gas entry into the chambers. A plurality of helical members surrounded by a large open tube and pierced by a small open tube channel all of the gases through a bulkhead wall which divides the muffler housing into two volumetrically generally equal portions. The chambers on either side of the tube and helical member cluster are substantially longer than the tubes joined by the helix members.

Abstract: A heat and sound insulation device including a heat and sound insulation material composed of a laminated body comprising elongate glass fibers and ceramic fibers mixed therewith, the heat and sound insulation material having an inner surface entirely exposed in an exhaust passage for increased heat insulation, sound insulation, and durability.

Abstract: An exhaust silencer for an internal combustion engine, has an inlet, a noise-attenuation chamber containing a noise-attenuation matrix, and an outlet. The noise-attenuation chamber is of rectangular cross-section, and has one transverse dimension which is substantially larger than the other transverse dimension. The noise-attenuation matrix is constituted by a plurality of flat plates made of a material which is heat resistant and corrosion resistant, the plates being placed in spaced parallel relationship.

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.