Abstract: Exemplary air amplifiers described herein can utilize a high-pressure stream of gas to accelerate a low-velocity stream of gas to provide a high-velocity, high-volume stream of gas. This high-velocity, high-volume stream of gas can generate unwanted noise as the high-velocity, high-volume stream of gas propagates through the air amplifier. The exemplary air amplifiers described herein can passively and/or actively suppress, for example, diminish, re-tune, or even completely cancel, the unwanted noise as the high-velocity, high-volume stream of gas propagates through these exemplary air amplifiers. The exemplary air amplifiers described herein can include one or more absorption materials to passively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas. The exemplary air amplifiers described herein can generate multiple noise suppression waves to actively suppress the unwanted noise generated by the high-velocity, high-volume stream of gas.

Abstract: A turboshaft engine includes an inlet, a swirl frame mounted downstream of the inlet, and an inlet seal mounted to one of the inlet and the swirl frame extending toward the other of the inlet and the swirl frame. The inlet seal includes a support member and an elastomeric member extending from a first end portion coupled to the support member to a second, cantilevered end portion.

Abstract: A vehicle air intake assembly is disclosed. The assembly includes a housing, a conical filter, and optionally may also include an inlet cowl. The housing and filter decrease in diameter from an inlet or distal end toward a proximal or outlet end. The shape of the housing guides the air into a smaller cross-sectional area and induces a Venturi effect on the airflow passing through the housing and filter. The housing decouples the filter from an engine inlet and the proximal or outlet end of the housing is sized so as to attach to the engine inlet and provide a smooth transition for the air leaving the housing and entering the engine inlet.

Abstract: A granule reactor (10), an apparatus comprising said reactor and a method implemented by said apparatus are described for treating polluting agents present in industrial gases, particularly but not only, when such gases comprise NOx, volatile organic compounds (VOCs), carbon monoxide (CO), hydrocarbons and similar pollutants. The pellet reactor is adapted to be used in the treatment of industrial gases, capable of treating industrial gases and removing particulate from said gases while maintaining a constant efficiency. Moreover, a method of treating the polluting agents present in industrial gases by means of said pellet reactor, and a pellet reactor adapted to implement said method of treatment are described.

Abstract: A filter includes a plurality of annular filter elements arranged in axially staggered relation. An axial flow path includes a plurality of flow path segments, some being filtered by a respective filter element, and others bypassing a respective filter element. Various combinations are provided.

Abstract: A silencer installed in a fuel cell system includes a plurality of expansion chambers connected to a predetermined apparatus of the fuel cell system, wherein the plurality of expansion chambers serially reduces acoustic noise of air discharged from the predetermined apparatus and a resonator connected to an expansion chamber of the plurality of expansion chambers, wherein the resonator reduces acoustic noise received from the expansion chamber in another frequency band, which is different from a frequency band of the acoustic noise reduced by the plurality of expansion chambers, where one of the plurality of expansion chambers comprises an inlet pipe which receives air from the predetermined apparatus, another of the plurality of expansion chambers comprises an outlet pipe which discharges air flowed into the plurality of expansion chambers, and an intermediate pipe is disposed between the plurality of expansion chambers.

Abstract: A silencer device (10) for connection to a piston compressor of a motor vehicle: a housing (11) with an inlet (12) connected to a suction line or to an air outlet of a piston compressor, and an outlet (13) connected to an air inlet of a piston compressor or to a compressed air line. A throughflow air duct (20) extends through the housing. A quarter-wave resonator (30) in the housing has an elongate resonator duct (31) which is curved in its longitudinal direction, has at one end an inlet aperture (32) situated in a wall of the throughflow duct, and has a cross-sectional area larger than or equal to that of the throughflow duct. The other end (33) of the resonator duct is closed. A motor vehicle has such a silencer device.

Abstract: A muffler for a turbo engine or piston engine, particular a screw compressor, includes a housing (1.1-1.3); a disk arrangement having at least one disk (3, 4, 5) which is fastened to the housing; a pipe arrangement which is fastened to the disk arrangement and which has at least one pipe (2.1, 2.2) for guiding a fluid of the turbo engine or piston engine; and a vibration-damping jacket (9) of dimensionally stable material which at least partially covers the outer side of the housing (2.2). At least one elastic element (3.3, 4.3, 6, 7, 8) is arranged between the pipe arrangement and the housing.

Abstract: An acoustic resonator adaptable to a sound chamber is designed to decrease a sound pressure while increasing a particle velocity of medium particles in a low frequency range without increasing the overall size thereof. The acoustic resonator is constituted of a pipe member having one opening end and a resistance member embracing a high resistance region and a low resistance region. The resistance member is inserted into the pipe member such that one end thereof matches the opening end of the pipe member while the other end thereof is disposed at a predetermined position inside a hollow cavity of the pipe member. The high resistance region embraces an antinode region of the particle velocity distribution with respect to a standing wave occurred in the hollow cavity at a resonance frequency, thus causing an acoustic phenomenon decreasing the resonance frequency compared to a single unit of the pipe member.

Abstract: A method of designing/making an acoustic side branch resonator structured to be coupled to a standpipe of, for example, a nuclear power plant, wherein the acoustic side branch resonator includes a plurality of wire mesh elements for damping purposes. The method includes determining a resonant frequency of the standpipe, determining an active length of the acoustic side branch resonator using the resonant frequency, and determining a particular number of the wire mesh elements to be used in the acoustic side branch resonator and a pitch of each of the wire mesh elements using momentum and continuity equations of a compressible fluid.

Abstract: A resonator for a vehicle is provided, including a housing having at least one chamber formed therein. The housing has at least one aperture formed in a wall thereof. The housing is in fluid communication with an air conduit of the vehicle. At least one flexible member is disposed within the chamber of the housing. The flexible member includes an outer portion and an inner extension protruding from the outer portion which vibrates to attenuate low frequency sound energy transmitted from the air conduit.

Abstract: An internal combustion engine capable of efficiently supplying air to an exhaust path even in a high load state. The internal combustion engine includes a convergent section, a divergent section, and a branch section. The branch section branches a shock wave, propagating in a downstream direction at a higher velocity than exhaust gas flowing into an exhaust path from a combustion chamber when an exhaust valve is opened, from a portion of the exhaust path which is upstream with respect to the divergent section, and propagates the shock wave back to the exhaust path. The exhaust gas is caused to pass the convergent section and to collide against the shock wave between the branch section and the divergent section so as to increase the pressure of the exhaust gas in the convergent section. Such exhaust gas is caused to pass the divergent section to generate a new shock wave.

Abstract: An internal combustion engine capable of improving cleaning efficiency by preventing an increase in the temperature of the exhaust gas to lessen the deterioration of the catalyst. The internal combustion engine includes a convergent section, a divergent section, and a branch section. The branch section branches a shock wave, propagating in a downstream direction at a higher velocity than exhaust gas flowing into an exhaust path from a combustion chamber when an exhaust valve is opened, from a portion of the exhaust path which is upstream with respect to the divergent section, and propagates the shock wave back to the exhaust path. The exhaust gas is caused to pass the convergent section and to collide against the shock wave between the branch section and the divergent section, so as to increase the pressure of the exhaust gas in the convergent section. Such exhaust gas is caused to pass the divergent section to generate a new shock wave and to decrease the temperature of the exhaust gas.

Abstract: An internal combustion engine includes a structure that increases the velocity of exhaust gas. The internal combustion engine includes a branch section arranged to branch a shock wave propagating at a higher velocity than exhaust gas and to guide the branched shock wave, and a reflecting section provided in the branch section. The reflecting section is arranged to reflect and return the shock wave back to an exhaust path and cause the shock wave to collide against the exhaust gas, thereby increasing the pressure of the exhaust gas. In accompaniment with the exhaust gas passing a divergent section of a convergent-divergent nozzle, a new shock wave propagating in a downstream direction in the exhaust path is generated, and the temperature and pressure of the exhaust gas are decreased.

Abstract: A gas-turbine exhaust cone includes a cone shaped outside cone 1 closed in a flow direction, an inside cone 2 arranged in the outside cone 1 over at least part of the length of the exhaust cone, with the inside cone 2 being connected to the outside cone 1 via at least one helical partition wall 3, thereby forming an interspace 4 between the outside cone 1 and the inside cone 2. The interspace 4 is connected to inlet openings 5 at its inflow side and opens at an exit side 6 towards an interior 7 of the outside cone 1. A dampening element 8 is arranged in the outside cone 1 adjacent to the exit side 6 of the interspace 4.

Abstract: The exhaust chamber for a motor vehicle exhaust line includes: a main envelope defining a main enclosure and having an exhaust gas inlet and an exhaust gas outlet; and at least one saucer-shaped shell having an opening defined by a peripheral edge of the shell, the or each shell being tightly connected to an outside surface of the main envelope along the peripheral edge, the shell, with the main envelope, defining a secondary enclosure. The main envelope has, beneath the shell, a plurality of perforations for placing the main enclosure in communication with the secondary enclosure. The main envelope has, in a first area located beneath the shell, at least one slot for increasing the elasticity of the first area, and/or the main envelope has, in a second area that is not covered by the shell, at least one rib for increasing the stiffness of the second area.

Abstract: A method and system for reducing pulsation in lateral piping associated with a gas compressor system. A tunable side branch absorber (TSBA) is installed on the lateral piping. A pulsation sensor is placed in the lateral piping, to measure pulsation within the piping. The sensor output signals are delivered to a controller, which controls actuators that change the acoustic dimensions of the SBA.

Abstract: An apparatus comprising includes a conduit portion having a conduit inner surface and a conduit outer surface, and a plurality of chambers in fluid communication with the conduit portion. The chambers include a first chamber defined, at least in part, by a first outer housing and a first chamber volume. The first chamber is in fluid communication with the conduit portion. A fluid is permitted to flow between the conduit portion and the first chamber through a first flow area. The chambers also include a second chamber defined, at least in part, by a second outer housing and a second chamber volume. The second chamber is in fluid communication with the conduit portion. A fluid is permitted to flow between the conduit portion and the second chamber through a second flow area. The first chamber volume is generally equal to the second chamber volume and the first flow area is greater than the second flow area.

Abstract: A muffling device has a muffling piece that is placed in an airflow path and muffles sound caused by airflow, and a drive unit that performs one of rotation and movement of the muffling piece.

Abstract: A resonator is disclosed which includes: a sleeve insert and an outer duct sealingly coupled to the sleeve insert. The sleeve insert has a wall with a first aperture in the wall at a first axial distance, a second aperture in the wall at a second axial distance, and a rib extending radially outwardly with the rib located between the first and second apertures. The outer duct sealingly couples to the sleeve insert proximate first and second ends of the inner sleeve and at the rib. The sleeve insert and the outer duct are formed of plastic materials which are coupled by welding or via o-rings placed on the sleeve insert. Cavities, in the vicinity of the apertures, are formed in the outer duct. The cavities, which are fluidly coupled to the sleeve insert via the apertures, attenuate noise.

Abstract: The present invention relates to an acoustic attenuation device for an intake line of an internal combustion engine and to an intake line such as this incorporating same. An acoustic attenuation device according to the invention is intended to have a flow of pressurized gaseous fluid passing through it and comprises: a conduit structure which has a tubular wall ending in two ends, these respectively being the fluid inlet and fluid outlet ends, which are able to be incorporated into the intake line, and at least one resonance chamber which is arranged on the outside of this structure and which communicates therewith via at least one opening formed in said wall, the or each chamber being axially delimited by two transverse partitions.

Abstract: An exhaust system comprises a muffler and a Helmholtz resonator. The muffler comprises an exhaust inlet aperture for receiving exhaust gas into the muffler, an exhaust outlet aperture for discharging exhaust gas from the muffler, and a resonator aperture. The Helmholtz resonator is at least partially external to the muffler and in acoustic communication with the resonator aperture. An associated method is disclosed.

Abstract: A method of improving scavenging operation of a two-stroke internal combustion engine. The exhaust pressure of the engine is analyzed to determine if there is a pulsation frequency. Acoustic modeling is used to design an absorber. An appropriately designed side branch absorber may be attached to the exhaust manifold.

Abstract: A sound generator for a vehicle is provided, including a hollow drum having a sound radiation panel structurally and acoustically coupled thereto. The drum has an aperture formed in an outer wall thereof. The drum is adapted to be in fluid communication with an air conduit of the vehicle. The sound radiation panel covers at least a portion of the aperture and is adapted to radiate sound energy to at least one of an engine compartment and an interior of the vehicle. A vehicle system including the sound generator and a method for manufacturing the sound generator are also provided.

Abstract: A muffler for reducing the sounds of combustion gases exhausted from an internal combustion engine. The muffler including an elongated fluid passage extending between an inlet and an outlet such that the outlet is in fluid communication with the inlet. The inlet of the muffler being connectable with the gases exhausted from the engine and the outlet being connectable with the atmosphere. The passage having a first side region and a second side region circumferentially spaced from the first region with a fluid passage in at least one of the first and second side regions. The muffler further including a side attenuation sound chamber adjacent the at least one of the side regions wherein the chamber is circumferentially spaced from the other of the at least one side region.

Abstract: An exemplary noise damper for a compressor of a turbocharger includes a compressor housing comprising a cavity substantially adjacent a gas flow surface of a conduit to a compressed gas outlet of the compressor housing and an insert that spans the cavity and forms a wall of the cavity where the wall includes one or more openings to the cavity to thereby allow acoustic energy to be damped by the cavity. Various other exemplary technologies are also disclosed.

Abstract: The exhaust chamber for a motor vehicle exhaust line includes: a main envelope defining a main enclosure and having an exhaust gas inlet and an exhaust gas outlet; and at least one saucer-shaped shell having an opening defined by a peripheral edge of the shell, the or each shell being tightly connected to an outside surface of the main envelope along the peripheral edge, the shell, with the main envelope, defining a secondary enclosure. The main envelope has, beneath the shell, a plurality of perforations for placing the main enclosure in communication with the secondary enclosure. The main envelope has, in a first area located beneath the shell, at least one slot for increasing the elasticity of the first area, and/or the main envelope has, in a second area that is not covered by the shell, at least one rib for increasing the stiffness of the second area.

Abstract: A high-performance muffler assembly for exhaust system of an internal combustion engine. The muffler assembly comprises an elongated casing having an inlet port and an exit port, a first pipe disposed within the casing and having an inlet end in fluid communication with the inlet port and an outlet end selectively fluidly connected to the exit port of the casing, and a first valve mounted within the casing. The first valve is selectively movable between a closed position and an open position for regulating an exhaust gas flow through the first pipe. The muffler assembly is operable in a number of different modes of operation including a high-performance mode, an exhaust braking mode, a reverse-flow mode, etc., determined by the positions of the first valve of the muffler assembly.

Abstract: Silencer of exhaust gases, in particular for motor vehicles, comprising an inlet opening (13) and a cylindrical coat (1) provided with an outlet pipe (29) at its opposing end, said cylindrical coat (1) has an internal division into at least four working sections (5, 6, 7, 8) containing axially arranged elements, especially suppression elements, expansion chambers, a whirl chamber, resonators and twirling, deflecting, and accumulating elements, confined with at least three crosswise arranged partitions (2, 3, 4), while the cylindrical coat (1) opposite to the outlet tube (29) is provided with an inlet section (10) freely encompassing its first working section (5) provided with inlet holes (18) of exhaust gases, said inlet section (10) being attached to the surface of the cylindrical coat (1).

Abstract: A muffler includes a case divided into three chambers by two baffles. The first chamber is closest to, and the third chamber is farthest from, the exhaust pipe. An inlet pipe has a first end connected to the exhaust pipe, and a second end in fluid communication with the third chamber. An outlet pipe expels exhaust and water from the first chamber to the exterior. A connecting pipe provides fluid communication between the first and third chambers. The second end of the inlet pipe is above the bottom interior surface of the outlet pipe. The inlet pipe may have holes in the second chamber, above the bottom interior surface of the outlet pipe. The connecting pipe may have holes in the second chamber. The baffles may have holes for the water to flow from the second and third chambers to the first chamber. Also, an exhaust apparatus utilizing the muffler.

Abstract: A sound-cancelling flow-through muffler includes a linear first inner passage, and a curved or zig-zagged second outer passage that wraps around or surrounds the inner passage and that is situated between the linear first inner passage and an exterior wall of the muffler. The outer passage has a length that is equal to, or a multiple of, one-half the wavelength of sound to be cancelled by the muffler such that sound exiting the inner and outer passages destructively interferes or cancels in a sound cancellation or conversion chamber. In addition, the walls of the outer passage serve as a heat sink to extract heat from the exhaust stream and conduct the heat to the outside of the housing. Alternatively, the outer passage may have a closed such that reflects sound back toward the inner passage for cancellation, the walls of the outer passage continuing to serve as a heat sink to extract heat from the exhaust stream and conduct the heat to the outside of the housing.

Abstract: An adjustable Helmholtz resonator assembly is provided having an active state and an inactive state. In the active state the Helmholtz resonator assembly is operable to attenuate pressure pulsations within air passing therethrough. In the inactive state the Helmholtz resonator assembly does not attenuate pressure pulsations within air passing therethrough. The Helmholtz resonator assembly is preferably configured to be mounted within an intake system of an internal combustion engine.

Abstract: A muffler assembly includes first and second muffler components that are each formed as a single piece. The first muffler component includes a first outlet pipe portion, a first bypass pipe mount portion, and a first resonator shell portion. The second muffler component includes a second output pipe portion, a second bypass pipe mount portion, and a second resonator shell portion. The first and second muffler components are positioned in an overlapping relationship such that respective portions are aligned with each other to form an outlet pipe, a bypass pipe mount, and a resonator shell. A noise attenuation valve assembly is also installed within the first and second muffler components. The bypass pipe mount is positioned at a non-perpendicular orientation relative to the outlet pipe such that a bypass pipe having a straight end mount can be received within the bypass pipe mount to bypass the noise attenuation valve assembly.

Abstract: In a muffler duct including a duct body and a resonance box, the inside of the duct body and the inside of the resonance box are made to communicate directly with each other not through a cylindrical member. In the partition wall of the resonance box, a gas vent opening portion, which is composed of a gas vent opening having a through hole shape and a gas-permeable member having a gas vent passage of a labyrinth shape for covering said gas vent opening, is formed at a position to confront a communication opening, through which the inside of the duct body and the inside of the resonance box communicate with each other.

Abstract: A resonator is arranged in an intake system including a pipe section for partitioning an intake port from an intake passage that communicates the intake port with a combustion chamber of an engine, the resonator including: a branch pipe having one end branching to the pipe section and the other end closed so that a silencing chamber is defined therein; and at least one partition wall for partitioning the silencing chamber into at least one pneumatic spring chamber, the partition wall having a natural frequency lower than the frequency of silencing target sound of intake noise propagated from the intake passage.

Abstract: The present invention relates to a muffler for an exhaust system of an internal combustion engine, including a housing having at least one absorption chamber which is filled with an absorbent material that has an absorbent effect for airborne sound, a straight-through pipe that carries exhaust gas during operation of the muffler and passes through the housing, and at least one blind pipe that is connected at one end laterally to the straight-through pipe and is sealed at the other end. The blind pipe has a wall that is acoustically transmissive for airborne sound in an area running in the absorption chamber.

Abstract: An air induction system for an engine to remove contaminants from intake air prior to delivery to the engine. The system includes a filtering unit having barrier filter panels attachable to a mounting frame. The filter panels are interchangeably usable. A juncture between first and second filter panels and the mounting frame is located at a region of relatively lower quantity of intake air flow. The juncture includes lugs on the filter panels which facilitate interchangeability. An opening above the filtering unit permits easy installation and removal of filter panels.

Abstract: Aspects of the invention are directed to a system for improving the damping performance of an acoustic resonator. According to aspects of the invention, a resonator, such as a Helmholtz resonator, can be attached to a surface of a combustor component in a turbine engine. The combustor component includes a region in which a plurality of passages extend through the thickness of the component. The resonator is attached to the component so as to enclose at least some of the passages. The passages are in fluid communication with a cavity defined between the component surface and the resonator. Resonator performance is a function of the length of the passages in the component. According to aspects of the invention, resonator performance can be improved by reducing the length of the passages in the component by reducing the thickness of the component in a region that includes the plurality of passages.

Abstract: An interference-based exhaust noise attenuation device and method for exhaust flow from an internal combustion engine that generates compressive waves in the exhaust flow. The device includes at least a direct path for the exhaust flow; a looped path for the exhaust flow, with volumes of the direct path and the looped path differing by an amount that results in a staggered rearrangement of the compressive waves in the paths; a splitter that splits the exhaust flow into the direct path and the looped path; and a merger that merges the exhaust flow from the direct path and the looped path. When the exhaust flow from the direct path and the looped path are merged, at least some noise cancellation occurs. In other embodiments, plural direct paths, looped paths, splitters, and/or mergers can be used in various combinations.

Abstract: A muffler system is provided for use with an auxiliary power unit. In one embodiment, and by way of example only, the system includes an outer can, an annular baffle, and a tube. The outer can has a sidewall including a forward end, an aft end, and a cavity extending therebetween. The sidewall is disposed about a first longitudinal axis, and the cavity has a first cross-sectional area and a smaller second cross-sectional area. The annular baffle is coupled to and extends radially inward from the outer can sidewall and has an opening that is disposed about a second longitudinal axis that is non-coincident with the first longitudinal axis. The tube extends through the annular baffle opening and is spaced apart from the annular baffle to define a radial gap therebetween, comprises acoustic material, and has a length and a substantially uniform cross-sectional area along the length.

Abstract: The shell main body for a muffler includes an inner shell in a cylindrical shape with a cross-section of an imperfect circle defined by small arc portions alternating with large arc portions; and an outer shell wrapping the inner shell and formed in a cylindrical shape similar to the inner shell. An end portion of the inner shell and an end portion of the outer shell are overlapped in a circumstantial direction of the shell main body to form a shell overlap portion that is capable of discharging vapor in a gap of the large arc portions formed between the inner shell and the outer shell into one of an outside and an inside of the shell main body. This shell overlapping portion is located in one of the small arc portions.

Abstract: A resonator and method of designing a resonator including a cavity having an effective length that exceeds ?/8 such that a standing wave having an anti-node will form in the cavity. First and second necks each having first ends are attached to and in fluid communication with the cavity, the first neck being positioned adjacent the anti-node and thereby operable to interfere with said standing wave.

Abstract: A control system (10) controls a variable acoustical damping device (20) disposed in a sound producing channel (5) of a vehicle engine (1). The control system includes a controller (12) and a selection device (14). The controller is coupled to the variable acoustical damping device and stores a plurality of control patterns (A. B) for different levels of acoustical damping of the acoustical damping device. The selection device outputs a selection signal to the controller so that the controller controls the variable acoustical damping device based on one of the control patterns corresponding to the selection signal.

Abstract: The present invention provides a resonator for attenuating acoustic vibration from an air intake passage. The resonator includes a neck, a resonator chamber, a piston-type member, and an actuator. The neck is attached between the air passage and the resonator chamber. The neck has two overlapping portions allowing the neck to extend within the resonator chamber. The piston-type member is located within the resonator chamber and is translated by the actuator to change the volume of the resonator and the neck length. By changing the volume and neck length of the resonator, the frequency attenuated by the resonator can be adjusted.

Abstract: A suction apparatus is provided with noise reduction means in one or more airflow passages for reducing noise emission from an airflow generator or the like, wherein at least one airflow passage is provided with at least one indentation with a predetermined depth extending substantially perpendicularly to the general direction of the noise in the passage.

Abstract: A communicating pipe is disposed on an outer periphery of an air intake pipe, and a conduit is formed so as to be parallel to an air intake passage. A plurality of first communicating apertures are disposed through the air intake pipe so as to be arranged in a single row in a conduit direction and communicate between the conduit and the air intake passage. A resonance chamber is mounted to the communicating pipe so as to communicate with a first end of the conduit. A movable member is disposed so as to be movable in the conduit direction by sliding in contact with the inner wall surface of the communicating pipe. A second communicating aperture is disposed through the movable member so as to be placed above the first communicating apertures. A communicating channel length between the air intake passage and the resonance chamber is adjusted by changing a position of overlap of the second communicating aperture relative to the first communicating apertures by moving the movable member in the conduit direction.

Abstract: An acoustic fluid machine includes an acoustic resonator, a valve device, a piston, and an actuator. The acoustic resonator has a larger-diameter base and a smaller-diameter upper end. The valve device is provided on the upper end of the acoustic resonator and has a sucking hole and a discharge hole. The piston is provided in the base of the acoustic resonator and has a surface such that the distance between the upper end of the acoustic resonator and the upper surface of the piston is substantially constant over the whole surface of the piston. The actuator is connected to the piston and reciprocates the piston at high speed axially with a very small amplitude so that a gas is sucked into the acoustic resonator via the sucking hole and discharged via the discharge hole by virtue of pressure fluctuations within the acoustic resonator.

Abstract: An active exhaust muffler for an exhaust system of an internal combustion engine, having a housing through which a pipe system passes, the pipe system designed to be permeable for airborne sound in a first space, having an antisound generator which is arranged in a second space and antisound acting upon a third space through a wall opening during operation, the wall opening being provided in a partition that separates the second space from the third space, whereby airborne sound is transmitted from the first space to the third space through a sound outlet. To increase the lifetime of the antisound generator and thus the exhaust muffler, a labyrinth is provided in the third space, blocking a direct path between the sound outlet and the wall opening, and providing at least one indirect bypass for the propagation of airborne sound between the sound outlet and the wall opening.

Abstract: A cylindrical shell main body constituting a muffler main body is formed of two layers of an inner shell and an outer shell and has a cylindrical shape with a cross section that is not a perfect circle but is defined by alternated small arc portions and large arc portions similarly to an oval, or the like. The outer shell of the shell main body has, in each of their small arc portions, four radially projecting beads continuously extending in a circumferential direction along the small arc portions and being a predetermined distance apart from one another in an axial direction, thereby allowing an upper and lower gaps between the inner shell and the outer shell in the respective large arc portions of the shell main body to communicate with each other through passages formed by the beads.

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