Abstract: In a muffler device of a motor vehicle, with a plurality of mufflers and an actuator for changing the flow resistance to the exhaust gases flowing through the mufflers, in order to change the damping characteristic, the actuator is provided in a pipe branch having an inlet and two outlets, each outlet being connected via a pipe to a muffler, and the throughflow cross section of the inlet being variable by means of the actuator.

Abstract: An exhaust gas muffler of multi-chamber construction includes an outer housing having an upper and lower half shell, an inner shell, and an inner exhaust gas duct through the exhaust gas muffler. The inner exhaust gas duct has at lease one curved outlet pipe that has a first curved section and a straight outlet end runs flush with the outer housing. The invention also covers a method for the production of the multi-chamber exhaust gas muffler.

Abstract: A tuned exhaust system for small two cylinder engines, the exhaust system including a pair of exhaust passage through which exhaust gasses pass. The exhaust passages are dimensioned to providing a tuning effect to the exhaust gasses for enhanced engine performance. The exhaust passages are not straight and elongated, but rather are sprialed, scrolled, coiled, or otherwise folded upon themselves at least twice. In this manner, the exhaust passages may be housed at least in part within a muffler having a significantly reduced overall size or profile, such that the muffler may be used in small engines.

Abstract: An exhaust that has two isolated baffle systems in one container. This allows the exhaust from one manifold to be muffled and exhausted independently of the other manifold's exhaust. Moreover, the muffler is the same size as existing mufflers, so that it fits into the space of the prior art mufflers. Using two independent muffler elements (baffles and outer covering cans) eliminates all of the problems discussed above and increases the engine horsepower without reducing efficiency. An outer shroud covers the two muffler elements and is also designed to act as a heat exchanger. Fresh air can be pulled through the muffler to be heated for cabin heat and for carburetor heat. The shroud has space around the muffler cans, through which the fresh air passes. Inlet and outlet ports are provided to allow hoses to be connected as needed.

Abstract: An exhaust gas muffler of multi-chamber construction includes an outer housing having an upper and lower half shell, an inner shell, and an inner exhaust gas duct through the exhaust gas muffler. The inner exhaust gas duct has at lease one curved outlet pipe that has a first curved section and a straight outlet end runs flush with the outer housing. The invention also covers a method for the production of the multi-chamber exhaust gas muffler.

Abstract: An easily controlled exhaust tube has a manifold. One end of the manifold is connected to a distal end of a connecting tube. Another ends of the manifold are extended with a left branch tube and a right branch tube. The left branch tube is directly connected to an outer tube of a first noise eliminating tube and the right branch tube is connected to an inner tube of a second noise eliminating tube which has a valve seat. The left and right branch tubes are enclosed by outer tubes. Glass fibers and stainless steel and cotton structure are filled in the outer tube. A connecting piece is welded between the first and second noise eliminating tubes. A valve is installed in the valve seat. A front and a rear sides of the valve seat have respective washers. The valve is controlled by a controller.

Abstract: A device to be interposed within the conduit of a fluid flow system to reduce or eliminate the noise associated with such systems. The device is made up of at least two cylindrical chambers, one within the other. The inner chamber is closed at the top, has a fluid entry port at the bottom, and a plurality of fluid exit nozzles symmetrically arranged about the side wall. The outer chamber is closed at the bottom and has a fluid exit port at the top. The entry port, exit port and inner chamber as well as the fluid flow system conduit have the same internal cross sectional areas. The sum of the cross sectional areas of the exit nozzles is equal to the cross sectional area of the conduit. The addition of a liquid exit port at the bottom of the outer chamber allows the device to also function to separate a gas from a fluid mixture. Multiple units may be utilized within a fluid flow system.

Abstract: A modular muffler that is quickly and easily adapted for use with a wide variety engines is disclosed. The muffler has a dimensionally standardized body member with end portions that may receive any of a number of adaptor end plates provided with various inlet and outlet configurations. The adaptor end plates are inwardly and outwardly adjustable relative to the body member end portions in order to vary the body member internal volume.

Abstract: A muffler assembly is disclosed allowing one or more outlet tips to be secured to an exhaust. The muffler comprises a casing having an outlet end including threaded holes or threaded bolts attached to the casing, an outlet tip with a tubular member and an annular flange connected to the tubular member, wherein the flange has a plurality of holes or incisions and wherein screws or nuts cooperate with the threaded holes or threaded bolts, respectively, to secure the outlet tip to the casing.

Abstract: An exhaust silencing device and method for silencing a turbogenerator includes a housing, an intake manifold, at least two exhaust outlet ports and flow channels which extend in a bifurcated path from the intake manifold to the exhaust outlet ports and which provide a length to height (or diameter) ratio permitting a compact fluid flow profile.

Abstract: A muffler for automotive vehicles. The muffler includes a passageway, an inlet at one end of the passageway, and a single outlet or dual outlets at the passageway's other end. The portion of the muffler connected to the inlet is substantially untapered. The portion of the passageway connected to the outlet or outlets tapers from wide to narrow away from the inlet and toward the outlet or outlets. This tapered geometry results in a very appreciable reduction of heat transmitted from the muffler back to the engine, increases engine performance, and produces a pleasant, deep sound while the engine is running.

Abstract: A twin muffler includes two muffling units connected in parallel to the exhaust post of an engine through a manifold, each muffling unit having a front accumulation chamber, a rear accumulation chamber, a perforated inner tube connected between the front and rear accumulation chambers, the perforated inner tube having a twisted middle section for causing exhaust gas to form a spiral flow, an internally tapered guide tube adapted to guide exhaust air from the perforated inner tube to the rear accumulation chamber, and a hopper-like exhaust endpiece adapted to guide exhaust gas out of the rear accumulation chamber.

Abstract: An exhaust gas cooling system for a vehicle includes a cooling fin system retrofit and a side exhaust pipe retrofit having an exhaust gas exit pipe having a first portion having a plurality of mixing portions which are either bends or internal mixing fins configured to mix vehicle exhaust gas, but not to restrict exhaust gas flow, a second portion fastened to the first portion and a chrome coated third portion fastened to the second portion and extending along the side of the vehicle. The cooling fin system retrofit includes an adjustable clamp and one or more cooling fins, each cooling fin having a base having a pair of upstanding arms, with one arm of the pair having a lip for engaging an arm of another cooling fin. An exhaust gas cooling system kit, a side exhaust pipe retrofit kit, a cooling fin kit are included.

Abstract: An exhaust system is provided with a structure that separates water from an exhaust stream and also attenuates the noise of the exhaust system. Water laden exhaust is directed from an inlet conduit through a perforated surface to precipitate water from the water laden exhaust stream. After the water is precipitated out of the exhaust stream, the gaseous portion of the exhaust stream continues from the inlet chamber 24 to an outlet chamber 28 and exits from the housing structure by passing through a first outlet conduit. The precipitated water passes from the housing structure through a second outlet conduit.

Abstract: An exhaust gas cooling system for a vehicle includes a cooling fin system retrofit and a side exhaust pipe retrofit having an exhaust gas exit pipe having a first portion having a plurality of mixing portions which are either bends or internal mixing fins configured to mix vehicle exhaust gas, but not to restrict exhaust gas flow, a second portion fastened to the first portion and a chrome coated third portion fastened to the second portion and extending along the side of the vehicle. The cooling fin system retrofit includes an adjustable clamp and one or more cooling fins, each cooling fin having a base having a pair of upstanding arms, with one arm of the pair having a lip for engaging an arm of another cooling fin. An exhaust gas cooling system kit, a side exhaust pipe retrofit kit, a cooling fin kit are included.

Abstract: An exhaustion pipe structure including a hollow tube body, a fitting ring, locking plates, locking screws, an exhaustion fitting pipe and a decoration. The decoration is replaceably fitted with the hollow tube body which is fitted around the exhaustion pipe of a car so as to beautify the exhaustion pipe.

Abstract: An exhaust gas muffler for an internal combustion engine of a portable, hand-guided working tool has a housing having an exhaust gas inlet, and exhaust gas outlet, and an outlet space, wherein the exhaust gas outlet opens into the outlet space. An outlet opening is provided downstream of the outlet space and has wall elements directing the exhaust gas flow in the exit flow direction. A rebound wall is positioned transverse to the exhaust gas outlet and delimits the outlet space while providing a connecting slot into the outlet opening. The connecting slot is spaced at a distance from the outer wall of the housing that extends substantially parallel to the rebound wall. A first ramp is positioned perpendicularly to the connecting slot and slants upwardly from the rebound wall to the outlet opening. A second ramp extends in a direction of longitudinal extension of the connecting slot from an end of the insertion slot opposite the first ramp to the edge of the first ramp opposite the connecting slot.

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 muffler for use with a pneumatic motor the muffler including a housing having a first longitudinal wall, a second longitudinal wall, a first lateral wall, a second lateral wall, and a front wall where the first and second longitudinal walls include an exhaust port and the front, longitudinal and lateral walls define a muffler chamber. The muffler also includes first and second baffle located in said muffler chamber. The first and second baffles include a first side and a second side, and each baffle extends away from a first lateral wall substantially parallel to the longitudinal walls and terminates in a baffle edge. The first and second baffles dividing the muffler chamber into at least two exhaust chambers, the baffle edges define a crossover opening for flowing an exhausted fluid to an adjacent exhaust chamber. A sound absorbing media along said first and second sides of said first and second baffles.

Abstract: Apparatus for use in combination with a compressed air powered tool having an air exit port to modify the sound of the tool during operation. The apparatus includes a helical coil compression spring having a plenum and defining restricted, radially disposed flow paths communicating with the plenum. A spring support holds the spring in position on the tool and air passing from the air exit port of the tool enters the spring plenum and passes through the restricted, radially disposed flow paths. An adjustment mechanism moves the coil spring segments, varies the length of the spring, and varies the size of the restricted, radially disposed flow paths. The spring support prevents bending of the spring.

Abstract: An exhaust system for vehicles and other devices with internal combustion engines such as boats, airplanes, lawnmowers, tractors, and the like, includes a sound attenuating chamber having a single, common opening in an imperforate container providing access for exhaust gases both to and from the container while attenuating the exhaust sound thereof. The system maintains low back pressure during operation. Resonator tubes and optional sound absorbing material may be used in the chamber to control exhaust sounds. An optional, remote-operated, sound control valve upstream of the chamber allows individualized control of the exhaust sound by the vehicle driver. An optional baffle in the exhaust outlet and/or an optional helical insert in the exhaust pipe further deadens the sound. In a preferred form, the system is attached downstream of a catalytic converter and includes dual sound attenuating chambers and dual exhaust outlets at the opposite vehicle sides between the front and rear wheels.

Abstract: An exhaust muffler for mounting on the transom of a powerboat in association with the exhaust pipes which extend through the transom. The muffler comprises a housing extending laterally across the stern of the boat and rearwardly from the transom to define an interior space. The housing has a floor located below the water line; opposed end walls; a front wall located adjacent to the transom with openings formed therein, through which exhaust gas can pass from the exhaust pipes; a rear wall having exhaust ports formed therein and a cover that encloses the interior space. Located within the enclosed space are muffler inserts secured to the floor and also to the front and rear walls. Each insert has a domed portion defining a muffling chamber that communicates with the respective exhaust pipe, and a second domed chamber defining an expansion chamber that communicates with the respective exhaust port located in the rear wall of the housing.

Abstract: The invention is directed to an exhaust gas muffler for an internal combustion engine such as a two-stroke engine for portable handheld tools such as a motor-driven chain saw. The engine includes a cylinder and a piston conjointly defining a combustion chamber wherein combustion gases are generated and discharged as a flow of exhaust gas during operation of the engine. The exhaust gas muffler includes a housing having a shell-like wall defining a chamber for receiving the exhaust gas from the engine. The housing has a primary outlet opening formed in the wall of the housing for passing a primary component flow of the exhaust gas out of the chamber in a first direction. The housing has a secondary outlet opening formed in the wall thereof for passing a secondary component flow of the exhaust gas out of the chamber in a second direction.

Abstract: An improved automotive exhaust system comprises a flared expansion chamber having two inlet ports at its narrow end and three outlet ports at its wide end. The inlet ports extend a predetermined distance into the chamber to form therein a pair of lips that function as dams against migration of reversion pulses back up the exhaust pipes. The total area provided by the outlet ports is greater than that provided by the inlet ports. Exhaust gases fed to the chamber can thereby expand as they traverse the length of the chamber and can pass freely from the chamber through the outlet ports. Reversion pulses, which tend to migrate toward the inlet ports along the interior surface of the chamber, encounter and are reflected by the reversion dams and thus are inhibited from migrating back up the exhaust pipes to the engine. Engine performance and usable power is thereby enhanced.

Abstract: A motorcycle covered by a cowl includes a power unit comprising an engine and a power transmission device enclosed by a cover within which an engine fan induces cooling air into heat transfer relation with said engine. A muffler device enclosed by the cowl has an air guide cover within which cooling air inducted into the power unit cover is passed thereinto in order to cool the muffler. According to an aspect of the invention the vehicle body frame has a hollow main frame operative to induce a flow of cooling air and for discharging it into cooling relation with the power transmission device.

Abstract: A sound attenuating device is provided for attenuating noise in an exhaust system. The attenuating device includes an inlet end, an outlet end and a constricted portion therebetween. In use, the attenuating device may be disposed in a tubular housing or may be an integral portion of a tail pipe, connecting pipe, or muffler. Further, a sound suppressing system is described including one or more attenuating regions including attenuating devices. The attenuating regions are spaced to attenuate desired frequencies. Expansion chambers formed between attenuating regions contribute to sound suppression.

Abstract: A sound absorbing muffler for a compressed air driven motor has first and second mutually confronting end walls connected by four side walls. A pad of sound absorbing material constructed from SAE No. F-7 polyester felt is contained in the muffler housing. An entrance port at the center of the first end wall supplies exhaust to the interior volume of the muffler housing. A series of depressions in the first end wall disperse the exhaust over a first planar surface of the pad of sound absorbing material. The porosity of the sound absorbing material permits the exhaust along with grease, oil or water carried by the exhaust to pass through the pad. The exhaust exits a second planar surface of the pad at the second end wall of the muffler housing and is discharged from the interior volume of the muffler housing through a plurality of louvers provided in the second wall of the muffler housing.

Abstract: A compressor includes at least one compression space for compressing refrigerant, at least one communication chamber into which the refrigerant is discharged from the compression space, a discharge pressure chamber, and at least one communications passage communicating the communication chamber with the discharge pressure chamber for feeding the refrigerant from the communication chamber into the discharge pressure chamber. The length of the passage is longer than the diameter of the passage.

Abstract: An engine exhaust apparatus in which an exhaust passageway of the engine is provided with a plurality of sound deadening passsages. One common exhaust passageway from the engine is branched into first and second exhaust passageways. Each of the first and second exhaust passageways has a silencer or muffler including first and second exhaust outlet tubes with a shift valve mounted in one of these exhaust outlet tubes. A control unit controls the shift valves to close both when engine speed is in a low region, to open one of them when engine speed is in a medium region and to open both when engine speed is in a high region.

Abstract: Sound muffling devices for marine engines for installation on the external portion of the transom of a marine vessel are attached in such a manner that any breakdown within the silencer causes no discharge of exhaust gases or cooling fluids into the interior of the vessel and the gases and cooling fluid continue to be discharged overboard. The silencer is designed to reduce, substantially, the noise level emitted by the engine under operation by the efficient mixture of gases and water through a series of baffles, with low resistance to gas flow that does not diminish engine efficiency. The gases and odors are emitted from the vessel at the centerline with distance and direction such as to reduce, substantially, emissions into the air environment. The device receives exhaust gas and cooling water from an exhaust pipe passing through the transom at the side of the boat and directs the gas athwart the boat to the center where it is exhausted.

Abstract: A pulsation damper is disclosed for use in a standard air-conditioning compressor for an automobile. The pulsation damper consists of a body portion and a cap portion and the cap portion has an outer diameter that is dimensioned to be press fit within the outlet opening of the housing of the air compressor. Thus, the pulsation damper can be retro-fit in a standard air compressor housing and will not increase the overall size of the housing or require modification in the connecting tubing. The body of the pulsation damper consists of longitudinal groove-like passages which direct the fluid flow from one of two internal compressor discharge lines to a point where it opposes and is intermixed with the fluid flow from another internal discharge line. This opposition and intermixing of the two fluid flow paths, which have pressure pulses which are out of synchronism with each other, tends to cancel or reduce such pulses.

Abstract: A gas silencing system for controlled sound attenuation of the exhaust gas in a motor vehicle comprises a sound attenuation muffler for exhaust gases. The system also includes means providing a bypass passage for gas to flow around at least part of the muffler. Bypass control valve is provided to allow selective regulation of the flow of exhaust through the muffler and the pass-pipe. The bypass control valve is responsive to a modulated pressure signal controlled by the driver of the vehicle. The invention also includes circuits for visually indicating the amount of bypass flow and the sound level of gas leaving the system.

Abstract: In an automotive vehicle installed with a V-6 engine, engine revolution speed and engine load are detected and a selector valve provided in a silencer is normally closed but it is opened when the engine revolution speed exceeds a predetermined engine revolution speed value when the 3rd order component of exhaust sound coincides with a longitudinal resonance frequency within a vehicle cabin when the vehicle is at acceleration. The selector valve which is normally closed is opened when the engine revolution speed exceeds a second predetermined engine revolution speed value when the 1.5th order component of the exhaust sound coincides with the longitudinal resonance frequency.

Abstract: A number of embodiments of silencing devices for marine propulsion units using acoustical lenses that are positioned across either the air inlet device, the air exhaust device or both. The acoustical lenses direct the sound waves in such a way so as to effect silencing while, at the same time, ensuring that water will not enter the engine combustion chambers. The invention is shown in conjunction with both outboard motors and inboard mounted engines.

Abstract: A muffler includes a cylindrical body, a gas passage pipe insertedly mounted within the cylindrical body, and a sound absorber mounted upon the gas passage pipe in an encircling manner. Gas is discharged from the gas passage pipe through the cylindrical body and sound absorber. The cylindrical body has a disk-like partitioning wall axially dividing the interior space thereof. The gas passage pipe has an outer flange and a plurality of pawls cooperating with the flange so as to clamp the partitioning wall therebetween.

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: Disclosed is an automobile muffler having a drain pipe communicating with the upperstream, upper half inside sound-deadening area of its outer pipe, thereby allowing the moisture of the air drawn into the sound-deadening space to leave for the surrounding atomosphere via the drain pipe prior to condensation of the moisture to water in the sound-deadening space, thus making it unnecessary to drain water from the muffler.

Abstract: A tail pipe structure of a control type muffler having a first outlet pipe and a second outlet pipe provided with a control valve inserted therein, wherein the first outlet pipe is in communication with the downstream side of the control valve of the second outlet pipe. The mechanism of the muffler is such that when the control valve is opened, the exhaust gases flow into the atmosphere from the first and second outlet pipes. Further, even when the control valve is closed, the exhaust gases in the first outlet pipe flow into the atmosphere therethrough while a part of the exhaust gases flow into the second outlet pipe from the first outlet pipe through the communication pipe and is then discharged into the atmosphere.

Abstract: A motorcycle embodying an improved exhaust device comprised of an expansion chamber that extends in part beneath the engine and transmission and which extends at least partially vertically upwardly adjacent to the transmission. A U-shaped inlet pipe delivers exhaust gases from the engine to the expansion chamber and a further expansion chamber is provided for discharging the exhaust gases to the atmosphere. Stainless steel, single thickness exhaust pipes deliver the exhaust gases from the engine exhaust ports to the expansion chamber.

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 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 sound attenuator may be directly threadedly connected to the exhaust port of a pneumatic device whose exhaust air is to be attenuated. A fail safe blowout plug is provided in the attenuator at the end remote from the exhaust port connection. A cartridge screen covering exhaust slots in the attenuator wall is trapped within an annular groove in the end of the attenuator remote from the exhaust port connection. The screen overlies a protective cover within the attenuator which extends over the blowout plug.

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: An adjustable motorcycle muffler affixable to the exhaust pipe of a motorcycle. The muffler includes a stationary ring which is affixed to the exit end of the muffler body and the stationary ring has several openings therethrough. An adjustable ring is affixed to the face of the stationary ring and is movable to increase or decrease the gas flow resistance through the stationary ring.

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: An exhaust dissipator device for a rocket exhaust has an inlet for connection to the exhaust and a plurality of smaller exhaust orifices spaced around its surface to dissipate the flow into a plurality of smaller jets. A deflector surface in the direction of exhaust flow into the container acts to further dissipate the flow and deflect it out of its original path. This may comprise an internal surface of the container, or a separate deflector plate spaced from the container surface.

Abstract: An internal combustion engine exhaust gas catalytic converter has coaxial inner and outer louvered tubes which define an annular catalyst bed. An outer shell coaxial with the inner and outer louvered tubes define a portion of a gas flow path downstream from the catalytic bed. The downstream flow portion has an annular outlet of smaller cross sectional area than the cross-sectional area of the inlet end of an upstream portion of the flow path. Heat expandable means maintain a constant density of catalyst beads within the catalytic bed. These heat expandable means preferably comprise a composition of ceramic fibers, vermiculite and a binder.

Abstract: An exhaust control system for use in an internal combustion engine for controlling the flow of exhaust gases discharged from the engine to the atmosphere. The apparatus determines a first condition representing the engine speed being higher than a predetermined value, a second condition representing the transmission being not in neutral, and a third condition representing the throttle valve being not at or near its closed position. A control circuit generates a command signal only upon simultaneous occurrence of the first, second and third conditions. The apparatus includes a device responsive to the command signal from the control circuit for increasing the effective area of the exhaust passage.

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.