Abstract: A device for silencing a flow includes at least one acoustic chamber through-flowed by gas, e.g., exhaust gas, at least one inlet pipe and at least one pipe or passage interconnecting two chambers or a chamber and an exterior environment or chamber and is designed with such cross-sectional area transitions, between passages and the chambers that the sound attenuation achieved by the device is high while the pressure drop across the silencer is low and that high attenuation at low characteristic frequencies of flow systems are obtained. The device may contain at least one of diffusers, monolithic bodies and catalysts. The passages may be curved or helical so as to allow for a low natural frequency. Embodiments with resonance chambers attenuating at selected frequencies are disclosed. A method for operating a vehicle including a combustion engine and a silencing system is disclosed.

Abstract: A rear end surface of a muffler is inclined so as to extend in parallel to the ground (E) when an all terrain vehicle is leaned against a support with rear ends of a rear carrier and rear portions of two rear wheels in contact with the ground (E) for storage. The volume of the expansion chamber of the muffler can be easily increased without making the muffler touch the ground when the all terrain vehicle is leaned against a support and without requiring large-scale modification. Thus, the silencing ability of the muffler of the all terrain vehicle can be improved.

Abstract: A muffler for pulsating gases, especially exhaust gases of internal combustion engines, comprises a housing into which an inlet conduit enters, from which at least on outlet conduit exits and which is divided by at least one partition wall into at least two chambers. In this muffler the flow cross section of a flow path connecting two chambers and/or of an outlet conduit can be varied by means of an adjustable closure element. An actuating element acting on the closure element is provided in the region of the exit cross section of the inlet conduit.

Abstract: An air pump for a fish-tank comprises a compartmental air chamber assembly formed by a base plate and a casing in the body. Hence, an indirect prolonged air path is formed in the air chamber assembly, resulting in a great reduction of noise generated while operating.

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 has an outer tube and an inner tube sealingly received in the outer tube. The inner tube has multiple shrink throats securely arranged therein and multiple through holes peripherally defined therein. Multiple baffles are formed between the outer tube and the inner tube and each of which has multiple openings. Every time when the exhaust air passes through the shrink throat in the inner tube, the speed of the exhaust air increases. Eventually, the efficiency of discharging the exhaust function increases. Due to the shrink throats, the backpressure from the exhaust air increasing, therefore hinders the power loss due to the early opening of the exhaust valve in the power (expansion) stroke.

Abstract: The transverse partition for separating an exhaust volume into two adjacent chambers includes at least one gas flow passage between the two chambers, the gas flow section through the passage being modifiable under drive from the difference between the pressures on the two sides of the partition. The partition comprises a wall pierced by at least one slit defined between two adjacent edges of the wall, which wall is elastically deformable under drive from the difference between the pressures on the two sides of the partition, between a rest position in which wall continuity is ensured, the two edges of the slit being substantially touching, and a deformed position in which the two edges of the slit are spaced apart so as to define said gas-flow passage between them.

Abstract: A muffler (20) is provided by upstream and downstream outer shells (28 and 30) and a single sole internal baffle (32 or 110 or 120), all three of which are joined to each other around an outer peripheral edge (34). The internal baffle defines a first chamber (36) between the internal baffle and the upstream outer shell. The internal baffle has an extension portion (38) extending away from the upstream outer shell and toward and into the downstream outer shell and forming second and third chambers (40 and 42) between the internal baffle and the downstream outer shell and forming multiple sound attenuating tubed passages (44 and 46, 114, 124 and 128) bounded by the downstream outer shell and the extension portion and connecting the second and third chambers on distally opposite ends (48 and 50) of the extension portion. The baffle has an opening (52) therethrough adjacent the extension portion and connecting the first and second chambers.

Abstract: An acoustic absorber includes an enclosure having a front opening and having a chamber communicating with the front opening for receiving an acoustic absorbing member which includes a housing having a number of apertures for receiving and dissipating noises. The housing may include a circular cross section or the other cross sections, and may include a casing having a number of apertures for receiving and dissipating the noises. The housing may be detachably secured to the enclosure with one or more catches which may engage with the lock grooves of the enclosure.

Abstract: A muffler in which in order to reduce a harsh high-frequency component exhaust noise as exhaust noise of a vehicle, and relieve a feeling of discomfort due to the exhaust noise, on at least one of an inner plate and an outer plate, a plurality of dot-shaped convex portions 15 and dot-shaped concave portions 16 are provided, and the convex portions 15 and concave portions 16 are alternately arranged to be surrounded with each other. Furthermore, the convex portion 15 is connected to the concave portion 16 by a curved surface.

Abstract: To provide a muffler structure capable of lowering muffler cost. A muffler structure is provided in which a sound absorbing material is laid on the inside surface of an outer tube. The sound absorbing material is retained by an inner tube made of a metal that is punched with a plurality of holes. The inner tube is divided into a plurality of expansion chambers. Exhaust gas from an engine is led into the fiat expansion chamber by an inlet pipe. The exhaust gas is discharged out after being supplied to the second and third expansion chambers in succession through the connecting pipes. In the muffler structure, the inner tube is made of an approximately flat metal that is punched with a plurality of holes by bending the metal into circular form until its opposite edges are butted to each other, and is fitted in the outer tube, with the butt portions not jointed, so that the butt portions will come behind the connecting pipe when viewed from the inlet pipe side.

Abstract: The invention relates to an exhaust-gas muffler on an internal combustion engine in a motor chain saw. The exhaust-gas muffler includes a housing (1) which is assembled of two housing shells (2, 3). The one housing shell (2) has an exhaust-gas inlet (4) and the other housing shell (3) has an exhaust-gas outlet (5). An inner wall (8) as well as a catalytic converting element (7) are provided in the inner space (6) of the muffler housing (1). The catalytic converting element (7) is mounted between the exhaust-gas inlet (4) and the exhaust-gas outlet (5). In order to ensure an adequate catalytic converting treatment of the exhaust gas at low gas counterpressure, it is provided to divide the entering exhaust-gas flow (10) and to conduct at least one of these component flows (23) in contact with the catalytic converting element (7). The component flows (22, 23) are brought together and mixed with other before exiting from the muffler housing (1).

Abstract: A valve for a control muffler includes: a valve element which is swingably journaled on a support shaft 5 supported by shaft holes 41a of a pair of first shaft supporting portions 41 inside the support shaft 5; bushes 6 which are respectively interposed between the support shaft 5 and a pair of second shaft supporting portions 33 that are disposed on the valve element to pivotally support the support shaft 5; and a coil spring which urges the valve element in a valve closing direction. In the valve, a welding rising portion 41b which protrudes in the axial direction is disposed on an outer opening edge of the shaft hole 41a of each of the pair of first shaft supporting portions 41, and the support shaft 5 is welded to tip ends of the welding rising portion 41b.

Abstract: A controllable muffler system is sued for use with an engine that produces a power by burning fuel. The system comprises a first passage section extending from the engine for having an exhaust gas of the engine flow therethrough. The first passage section has a catalytic converter mounted thereon. The system further comprises a dual passage section including second and third passage sections which extend separately from an end of the first passage section. The second passage has a control valve for controlling the flow rate of the exhaust gas flowing therethrough. The system further comprises a fourth passage section extending from respective ends of the second and third passage sections to the open air. The fourth passage section has a rear muffler mounted thereon. The system further comprises a control unit which controls the control valve of the second passage section in accordance with an operation condition of the engine.

Abstract: A muffler including a long outlet pipe 20 having an exhaust gas inlet pipe portion 21, a return pipe portion 22, an exhaust gas outlet pipe portion 23, and two turnaround pipes 24, 25 for connecting the three pipe portions 21, 22, 23 together in series. These pipe portions 21, 22, 23 are arranged in parallel with one another along a longitudinal direction of a shell 2, and in such a manner that longitudinal axes 21L, 22L, 23L of the pipe portions are positioned at respective vertices of a triangle.

Abstract: A muffler is described for muffling both positive power and compression brake type engine retarders. The muffler includes an outer shell defining an internal volume. A first, inner, perforated wall is spaced from the outer shell and defines a first, annular, volume therebetween. A first volume of packing material is positioned within the annular volume. An inlet tube is oriented within the internal volume. In certain embodiments, the inner perforated wall circumscribes at least a portion of the inlet tube, and extends a distance of at least 25% of the axial length of the outer wall. Both single and dual muffler systems are described. Methods of use and operation are also provided.

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: The present invention relates to a sound elimination structure for an air pump, especially an air pump which is used in an aquarium. The sound elimination structure includes a sound elimination device including an air chamber box, and an air chamber cover secured with each other and defining a plurality of chambers therein. The air chamber cover and the air chamber box are provided with air guide tubes, recesses, air holes co-operating with catch plates so as to increase the path of the air flow, thereby reducing the velocity of the air flow so as to eliminate the noise.

Abstract: A muffler for use with heavy duty trucks includes an outer wall defining an internal volume; an inlet tube oriented at least partially within the internal volume; an outlet tube construction oriented at least partially within the internal volume and including a diverging section and a choke extension; and a first baffle structure securing the outlet tube construction within the internal volume. A ratio of the diverging section axial length to the choke extension axial length is preferably less than 3:1. The first baffle structure defines an aperture arrangement therein to permit gas flow communication therethrough. A ratio of the total open area of the aperture arrangement to the perimeter, cross-sectional area of the first baffle structure is between 1:50 and 1:500. The mufflers are particularly useful for attenuating low frequency noise associated with the internal volume of cabs or sleepers in heavy duty trucks.

Abstract: A device (a silencer) for silencing a flow of gas, such as an exhaust gas, comprises at least one acoustic chamber (1, 2, 3) through-flowed by gas, at least one inlet pipe (6) for leading gas into the device and at least one pipe or passage (4, 12, 13) interconnecting two chambers or a chamber and an exterior environment or chamber and is designed with such features, including such cross-sectional area transitions between pipes or passages (4, 6, 12, 13) and the chambers (1, 2, 3) that the sound attenuation achieved by the device is high while the pressure drop across the silencer is low and that high attenuation at low characteristic frequencies of flow systems comprising the device are obtained. One or more diffusers (10a, 12a, 13a) for diffusing at least part of the gas flow, e.g., at the inlet to the chambers may be comprised in the device. One or more monolithic bodies or catalyzers may be comprised in the device. Devices with curved or helical passages (FIG.

Abstract: A silencer assembly having a cylindrical chamber having a closed cylindrical outer wall, a first end wall and a second end wall, the first end wall having an inlet therein, and the second end wall having an outlet therein, an internal annular chamber proximate the cylindrical outer wall, the internal annular chamber bounded by the cylindrical outer wall and by a perforated cylindrical inner wall, the internal annular chamber containing single strand fiberglass acoustic fill material, the internal annular chamber having no internal barriers therein, and, a perforated generally cylindrically shaped core located inside of the cylindrical chamber positioned in spaced relation to the internal annular chamber and also in spaced relation to the inlet and outlet, creating a generally annular shaped passageway for exhaust gas, the core containing single strand fiberglass acoustic fill material.

Abstract: A space efficient, structurally rigid, integrated muffler and bumper assembly is provided. The muffler and bumper assembly comprises an extruded skeleton, an energy absorbing bumper, and a bumper fascia. The extruded skeleton is formed such that internal cavities or passage flow chambers exist. In turn, the walls of the flow chambers maintain a plurality of holes, allowing for passage of exhaust gases between chambers. The extruded skeleton also has an inlet and outlet for exhaust gas flow. Arms having tabs on the ends thereof extend from the top and bottom of the extruded skeleton such that the energy absorbing bumper, which maintains recesses in the top and bottom portions, snap-fits with the extruded skeleton. The extruded skeleton/bumper assembly is welded or otherwise mechanically fastened to the vehicle frame rails. The bumper fascia is introduced over the extruded skeleton/bumper assembly generally masking the assembly with the overall vehicle design.

Abstract: A pulsation damper including an inlet, an outlet and a silencing member is disclosed. At least one of the inlet and the outlet is provided with a diffuser including a tubular member provided with a plurality of first openings, a plurality of second openings and reinforcement bodies extending around the tubular member. At least one of the second openings is covered by a plate having the first openings, smaller than the second openings therein.

Abstract: A time warp method of reducing noise in an exhaust stream includes the step of directing the exhaust stream into an inlet aperture of a sound cancellation chamber. The method also includes reflecting sound in the sound cancellation chamber toward the inlet aperture of the sound cancellation chamber. Another step of the method includes spreading the exhaust stream radially toward a periphery of the sound cancellation chamber. Yet another step of the method includes collecting exhaust from the periphery of the sound cancellation chamber in an outlet collector ring. Moreover, the method includes directing the exhaust collected from the periphery of the sound cancellation chamber substantially circumferentially about the sound cancellation chamber toward an outlet aperture of the outlet collector ring. Muffler devices for implementing the method are also disclosed.

Abstract: A muffler for an internal combustion engine having characteristically low back pressure and a pleasing sound is disclosed. The muffler comprises: (a) an elongated housing having an interior wall and including: (i) an inlet opening formed for the flow of exhaust gas into the housing, and (ii) an outlet opening formed for the discharge of exhaust gas from the housing; and (b) a partition shaped like a hollow pyramid, disposed in the housing and having interior surfaces and exterior surfaces, the exterior surfaces joining at a first end to form a pyramidal apex, the pyramidal apex pointing toward the inlet opening, and extending at a second end to form a rugose base, wherein the partition is disposed in the housing to form a plurality of spaces between the rugose base and the housing for the flow of exhaust gas.

Abstract: A silencer for reducing and canceling medium- to low-frequency vibration and noise that generate in the reciprocating internal combustion engines and in the reciprocating air compressors. An inlet pipe having many ports perforated therein in the radial direction is inserted in a hollow triangular pole in the lengthwise direction thereof, the gas is blown into the hollow triangular pole, and the pulsating gases reflected by the walls in the hollow triangular pole are caused to collide with each other to cancel the pulsation.

Abstract: A muffler includes an outer shell defining a chamber and a pair of inner plates positioned in the chamber. Each inner plate includes first and second folds partitioning each of the inner plates into a base portion, a first baffle portion, and a second baffle portion. The base portions cooperate to define a first baffle. The first baffle portions cooperate to define a second baffle and the second baffle portions cooperates to define a third baffle. The first, second, and third baffles partition the chamber defined by the outer shell into subchambers. The first baffle includes a tube and each of the second and third baffles include a tube-receiving aperture sized to receive the tube of the first baffle.

Abstract: A muffler includes an upstream outer shell, a downstream outer shell, and identical upstream and downstream inner baffles forming in combination an upstream expansion chamber, an inner expansion chamber, and a downstream expansion chamber. The upstream and downstream inner baffles divide the inner expansion chamber therebetween into a main chamber and first and second laterally spaced subchambers. The upstream and downstream inner baffles have respective sets of apertures therethrough laterally offset from each other and aligned with respective subchambers and communicating exhaust from the upstream expansion chamber through the set of apertures in the upstream inner baffle into the first subchamber and then flowing laterally through the main chamber to the second subchamber and then flowing through the second set of apertures into the downstream expansion chamber.

Abstract: More than two damping chambers 2A to 2C), a communicating pipe (6) for intercommunicating the damping chambers (2A, 2B) and another communicating pipe (7) for intercommunicating the damping chambers (2B, 2C) are provided. Both ends of the communicating pipes (6, 7) are closed by an end plate (9) and the respective damping chambers (2A to 2C) and inside of the communicating pipes (6, 7) are intercommunicated by communicating holes (8A) on an outer circumference of the communicating pipes (6, 7). Exhaust gas flows from the damping chamber (2A) to communicating holes (8A1), inside of the communicating pipe (6), communicating holes (8A2), the damping chamber (2B), communicating holes (8A3), inside of the communicating pipe (7), communicating holes (8A4), and the damping chamber (2C), thus damping exhaust noise by repeated effective contraction and expansion.

Abstract: A muffler includes an outer shell defining a chamber and first and second inner plates positioned to lie in the chamber. The second inner plate includes a base portion, a baffle integral with the base portion, and a tube portion integral with the base portion. The base portion includes an outer periphery defining a base portion boundary. The baffle extends between the base portion and the outer shell and the tube portion is positioned outside the boundary of the base portion.

Abstract: There is disclosed a muffler structure in which a valve opened/closed in accordance with exhaust gas pressure in a pipe is prevented from chattering by an inlet pipe provided with a first side hole and an outlet pipe provided with a second side hole with a valve biased by a spring to simultaneously close both the first and second side holes when the pressure is relatively low. When the pressure of the exhaust gas is relatively high, the pressure exerted on the valve by the exhaust gas in the inlet pipe is sufficient to open the valve and the exhaust gas introduced to the inlet pipe flows out to a second chamber via the first side hole, flows into the outlet pipe via the second side hole, and is exhausted to the outside of the muffler via the downstream outlet opening.

Abstract: A semi-active muffler for an internal combustion engine comprising a case defining a closed space with a predetermined capacity, the case being partitioned into first, second, and third chambers, a first bypass pipe for communicating the first chamber with the third chamber, a second bypass pipe for communicating the second chamber with the third chamber, an inlet pipe for introducing exhaust gas into the first and second chambers, an outlet pipe for exhausting the exhaust gas introduced into the third chamber from the first and second chambers respectively through the first and second bypass pipes, a valve for selectively opening a downstream end of the second bypass pipe according to a pressure level within the second chamber, and buffer means for reducing an impact and noise when the valve is opened and closed, wherein the buffer means comprises a gap kept between the valve and the downstream end of the second bypass pipe even when the valve is in a completely closed position.

Abstract: An expansion chamber, and first and second volume chambers on either side of said expansion chamber, are formed inside a muffler housing. Engine exhaust is led by an inlet tube to the first volume chamber, and an opening facing the expansion chamber is formed in an intermediate part of the inlet tube. Exhaust in the second volume chamber is discharged outside by a tail tube, and an opening is formed facing the expansion chamber in an intermediate part of the tail tube. A valve is provided for leading exhaust from the first volume chamber to the second volume chamber according to a pressure difference between the chambers. This forms two exhaust flowpaths. A resonance system with two degrees of freedom is thereby formed with respect to exhaust discharged via the two openings and the expansion chamber, and a high noise silencing efficiency is obtained.

Abstract: A muffler includes an outer shell defining a chamber and first and second tubes positioned in the chamber. The first tube has a flat side wall and the second tube has a flat side wall positioned adjacent to the fiat side wall of the first tube. Muffler further includes a baffle plate including a base and an edge defining a tube-receiving aperture and the first and second tube are positioned in the tube-receiving aperture.

Abstract: A silencer for reducing acoustic energy in an exhaust stream of gases from a combustion type source, particularly turbo-generators. In a preferred embodiment, the silencer includes an outer housing having at least one outlet opening and an inner housing provided at least partially within the outer housing. The inner housing has at least one inlet opening for receiving the exhaust stream along a flow axis and the inlet opening is in fluid communication with the outlet opening. The inner housing further includes an acoustic energy interface surface having acoustic absorbing elements oriented in a substantially non-normal direction to the flow axis. Sound absorbing material is preferably contained between the outer housing and the inner housing. In this way, the gas flow is effectively separated from the acoustic energy without significantly increasing the back pressure or resistance to flow of the exhaust stream.

Abstract: The invention concerns an exhaust silencer arrangement with a transverse exhaust silencer in a four-chamber type of construction, in particular for very small passenger-transporting motor vehicles, with a 3-cylinder rear-mounted engine and an exhaust gas turbocharger. The silencer comprises a housing which is composed of two half shells and accommodates a catalyst module in an integrated manner. The catalyst module, which does not have its own housing, forms a silencer system partition which divides the silencer into a 3-pot main chamber and an additional chamber which is in particular a resonator chamber and communicates with the main chamber via connection ducts formed in the half-shell housing.

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: A free-standing, compressed, hardened porous, resilient sheath of sound absorbing fibrous material for use in silencer or muffler pipes as the intermediate sound absorbing element between the inner perforated and outer sleeve elements of a three-element pipe is formed by (a) wrapping an uncompressed pad of fibrous material containing a thermo-setting hardening agent around a shaped mandrel having outside surface shape and dimensions conforming the outside surface shape and dimensions of the inner three-element muffler pipe, (b) subjecting the wrapped mandrel and sheath of uncompressed material to a pressure sufficient to conform the outside surface of the compressed pad to the inside surface shape and dimensions of the outer muffler pipe sleeve element, and to a temperature sufficient to set the thermo-setting hardening agent; and (c) removing the mandrel.

Abstract: A sound attenuation device for internal combustion engines includes a tubular core extending from an inlet end to an outlet end and having apertures formed therethrough to allow fluid communication between the interior and the exterior of the tubular core. One or more flanges position the tubular core in an exhaust passageway and are provided with apertures so that exhaust flowing through the exhaust passageway can flow either through the tubular core or through the flange apertures. End caps may be employed to close the inlet end of the tubular core and to provide a reduced diameter opening at the outlet end thereof.

Abstract: In a muffler, a first exhaust outlet pipe has an opening-closing device, and a second exhaust outlet pipe is connected or joined to the first exhaust outlet pipe at a downstream portion of the opening-closing device. An overall length of the second exhaust outlet pipe is greater than the distance between the above joint portion, at which the second exhaust outlet pipe is connected to the first exhaust outlet pipe, and an exhaust inlet end of the first exhaust outlet pipe, and the overall length of the second exhaust outlet pipe is shorter than or generally equal to an overall length of the first exhaust outlet pipe. With this construction, in a low engine revolution speed range, the production of abnormal sounds in the second exhaust outlet pipe is prevented.

Abstract: A muffler including paraboloid steel baffle chambers which may contain a continuously encased vacuum. These chambers can be shaped out of steel paraboloids. The exhaust of the engine (or noise source) can flow into the space between chambers and out of the muffler with high efficiency. The paraboloids are designed so that the noise is reflected to maximize a sound wave's path and minimize its intensity.

Abstract: A blower noise silencer comprises both an air turbulence stage and a noise absorption stage. The air turbulence stage includes a tubular screen enclosing a spiral vane wrapping around a central bore running through the air turbulence stage. The screen is surrounded by a hollow chamber. The noise absorption stage includes a hollow tubular screen surrounded by a chamber packed with sound dampening material. Each chamber in the silencer is closed other than through the screen that it surrounds whereas the screens open at one another and to opposite ends of the silencer to provide air flow movement into and out of the silencer.

Abstract: A muffler is described for muffling both positive power and compression brake type engine retarders. The muffler includes an outer shell defining an internal volume. A first, inner, perforated wall is spaced from the outer shell and defines a first, annular, volume therebetween. A first volume of packing material is positioned within the annular volume. An inlet tube is oriented within the internal volume. In certain embodiments, the inner perforated wall circumscribes at least a portion of the inlet tube, and extends a distance of at least 25% of the axial length of the outer wall. Both single and dual muffler systems are described. Methods of use and operation are also provided.

Abstract: A muffler for an internal combustion engine comprises: a plurality of chambers formed by a single partitioning wall inside an outer shell to be communicated with each other at the entrance and at the exit of the muffler; and a flapper-valve is provided in a communicating passage at the entrance, and a opening in the partitioning wall provide communication at the exit.

Abstract: A muffler (12) has first and second outer shell members (14 and 16), and first and second inner baffle members (18 and 20). The inner baffle members are identical to each other and parallel to each other and rotated 180.degree. relative to each other about an axis (22) perpendicular to such parallel extension. The baffle members have oppositely facing laterally offset formed expansion chambers (32 and 34) partially overlapped to provide exhaust flow communication therebetween. The structural combination enables usage of identical components (18 and 20), which improves manufacturing efficiency and provides a cost reduction.

Abstract: A cylindrically shaped muffler for a gas engine with substantially reduced noise. It includes: (a) a cylindrical shell having a shell-bore, an inlet and an outlet; (b) a plurality of first hollow cones suspended within but is supported by the shell-bore, the first hollow cones having their largest diameters smaller than that of the shell-bore with their apexes pointing toward the inlet of the cylindrical shell; (c) a plurality of hollow truncated second cones having their greatest diameters equal to that of the shell-bore in which they are supported in reverse to the first hollow cones and alternate therewith, so as to have their smallest diameter portions pointing toward the outlet of the cylindrical shell; and (d) a circular stopper suspended inside the hollow truncated second cone near its smallest diameter portion in such a manner to create eddy currents in gas flow so as to absorb noise.

Abstract: A first muffler (4) is connected to a rear end portion of the exhaust pipe (2) extending from a single-cylinder engine toward one side of a rear portion of the vehicle body and is provided on one side of the vehicle body. A second muffler (5) is provided on the other side of the vehicle body opposite to the first muffler (4) through a connecting pipe (6). An outer side surface near the front end portion of the first muffler (4) and the second muffler (5) are covered with first and second covers (7) and (8) both plated. Each of the exhaust pipe (2) and the first and second mufflers (4) and (5) have double-pipe structure with outside plated. Further, a front end portion of the second cover (8) is curved toward the center of the vehicle body, and a phantom line as a continuous frontward extension from the front end portion of the second cover (8) is positioned before the axis of the connecting pipe (6).

Abstract: The inner area of a muffler of an engine is partitioned into an expansion chamber, a first volume chamber and a second volume chamber. An inlet tube and the first volume chamber are connected by a first passage. The first volume chamber and a second volume chamber are connected by a second passage, and the second volume chamber and expansion chamber are connected by a third passage. The flow of exhaust gas reaching the expansion chamber via the first passage, second passage and third passage is blocked by a valve which opens according to a pressure rise of the exhaust gas. One of the two acoustic paths formed when the valve is open functions as a resonator having two degrees of freedom relative to the other path so that a high muffling effect is obtained.

Abstract: An intake silencer is designed as a broadband silencer for noises causes by intake of combustion air into internal combustion engines. To achieve the broadband effect, an axial sequence of resonator chambers with different volumes is formed by partitions which extend transversely to the intake pipe in a resonator that surrounds the intake pipe Each resonator chamber communicates through openings in the wall of the intake pipe with the air sucked through the intake pipe. By matching the open surface area of the openings, the thickness of the wall of the intake pipe in the area of the openings and the volume of the resonator chambers, a continuous broadband silencing may be set even over a wide frequency range, the range of practical interest in the present application extending combustion from to 1 to 10 kHz.

Abstract: In a muffler for internal combustion engine which is provided with a valve capable of closing and opening an open end of by-pass inner pipe, the opening and closing operation of the valve is performed via the exhaust gas pressure, without being affected by external factors. Also, the structure is simple and easy to be assembled. On a fixed shaft (36) supported in the vicinity of an open end (28a) of a by-pass inner pipe (28) is a valve (32) rotatably mounted. The valve (32) is urged against the open end (28a) by a coil spring (42), and when fitted in a flange part (38), it closes the open end (28a). When the revolving speed of the internal combustion engine is low, the pressure inside the by-pass inner pipe (28) is smaller than the operative force which is an addition of the urging force by the coil spring (42) and the external pressure. The open end (28a) is therefore closed.