Abstract: A high pass muffler for a pneumatic tool that allows for high pass through of exhaust air. The muffler dampens noise generated by the exhaust air by incorporating channels in walls of the muffler that act as Helmholtz resonators.

Abstract: A belt guard for an air compressor that includes an air compressor silencer. The guard includes a housing that includes a front cover and a back cover, and an accommodation portion. The air compressor silencer is provided inside the housing in the accommodation portion, where the air compressor silencer includes a spirally shaped silencer core, and the spirally shaped silencer core includes at least one spiral chamber comprising a core inlet and a core outlet. Additionally, a compressor installation that includes a motor, a compressor, a belt connected to a compressor shaft of the compressor element and a motor shaft of the motor, and a belt guard that includes a front cover and a back cover, and an accommodation portion, where the compressor silencer is provided inside the housing in the accommodation portion.

Abstract: A bilayer metamaterial silencer allows substantial fluid through the apparatus, while mitigating the propagation of sound through the apparatus, and while providing a form factor that is significantly more compact than previously-known devices. Moreover, illustrative embodiments allow a designer to specify one or both of the frequency or frequencies at which the apparatus mitigates sound propagation, and/or the bandwidth around the frequency or frequencies at which the apparatus mitigates sound propagation.

Abstract: A suppressor of an audible sound, especially useful for an impulse sound such as the report of a firearm, has a bore formed through a body for co-axial alignment with an exhaust of the device which produces the sound, one or more chambers within the suppressor body, each chamber having a spiral volume, and receivers for sound producing matter into the outer ends of each chamber so as to allow the sound producing matter to be expanded into the spiral volumes to reduce audible sounds presented at an output of the bore.

Abstract: A blower for an HVAC system of a motor vehicle. A fan is supplied with airflow by a duct having a bend adjacent to the fan that causes a low-pressure region at a face of the fan. A baffle is located immediately adjacent to the fan face and collocated with at least a portion of the low-pressure region to impede airflow through the face of the fan at that location. The baffle acts to reduce unwanted low frequency noise and improves the mechanical efficiency of the fan. The baffle covers a circular segment of the fan face and may have sound-suppressing features, such as ridges formed on at least one surfaces.

Abstract: A blower for an HVAC system of a motor vehicle. A fan is supplied with airflow by a duct having a bend adjacent to the fan that causes a low-pressure region at a face of the fan. A baffle is located immediately adjacent to the fan face and collocated with at least a portion of the low-pressure region to impede airflow through the face of the fan at that location. The baffle acts to reduce unwanted low frequency noise and improves the mechanical efficiency of the fan. The baffle covers a circular segment of the fan face and may have sound-suppressing features, such as ridges formed on at least one surfaces.

Abstract: An acoustic baffle for reducing noise of a centrifugal fan includes a base for mounting with a fan outlet and a projection extending from the length of the base at a back side of the base and curving away from a top surface of the base. The projection continuously tapers from the base to an apex that aligns with a center line of the base. The projection extends over the fan wheel and tapers from left and right sides of the outlet to a fan tangency point at a midpoint of the outlet and aligned with the apex, when the acoustic baffle is installed in the outlet. The acoustic baffle effects a gradual variation in radial and tangential airflow at the blower outlet, to reduce fan blade passage tone.

Abstract: A resonator is provided, having an adaptable resonator frequency for absorbing sound generated by a gas stream of a gas turbine. The resonator includes a neck section, a chamber and a deformable element being deformable under influence of a change of a gas turbine temperature of the gas stream. The shape of the deformable element is predetermined with respect to a respective gas turbine temperature. The neck section and the chamber form a volume of the resonator. The neck section forms a passage coupling the volume with the gas turbine. The deformable element is thermally coupled to the gas turbine in such a way that the shape of the deformable element depends on the respective gas turbine temperature. The deformable element forms a spiral and is installed to the neck section in such a way that an effective diameter of the neck section depends on the gas turbine temperature.

Abstract: A muffler providing a compact and low-profile form factor for small two-stroke engines is described, particularly useful for aerodynamic radio controlled aircraft. The muffler comprises a tuned internal header eliminating the need for an external header to mount the inventive muffler to the exhaust port of a two-stroke engine while maintaining enhanced engine performance, obviating the need for a conventional tuned-pipe exhaust.

Abstract: A fluid pathway is provided with a flow controller in at least a portion of its length wherein the flow controller comprises an active surface capable of influencing the fluid flow through the fluid pathway, the configuration of the active surface conforming to at least one logarithmic curve conforming to the Golden Section.

Abstract: A sound absorber comprises an elongated gas channel, through which a flowing gas passes in operation of the sound absorber; and at least one helical fixture mounted in a longitudinal section of the gas channel. The helical fixture defines a helical gas passage through the longitudinal section of the gas channel. Further, the helical fixture defines at least one longitudinal Helmholtz resonator within the gas channel which is excited by sound waves propagating in the flowing gas passing through the at least one gas channel.

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: A muffler for attenuating acoustic noise in a gas flow which includes a casing having an inlet and an outlet, such that the gas flow passes through the casing from the inlet to the outlet. The muffler also includes an acoustic trap disposed within the casing and which spans the distance between opposing top and bottom walls of the casing. The acoustic trap further comprises a first arcuate deflector having a concave frontside surface configured to direct the gas flow from the inlet through a first segment of an expanding spiral revolution, and one or more second arcuate deflectors which are radially offset from the first arcuate deflector and configured to direct a portion of the inlet gas flow through a remainder segment of the expanding spiral revolution.

Abstract: The invention presents a sound dampening flow channel device defining at least one flow channel having an inlet opening and an outlet opening, the flow channel being at least partly delimited by at least one acoustic energy dissipative wall. The outlet opening of the flow channel cannot be seen from the inlet opening and vice versa. Preferably, the acoustic energy dissipative wall presents, in relation to the interior of the flow channel, a smooth curvature.

Abstract: An exhaust system baffle is provided comprising a tube and a plurality of radially extending flanges mounted in surrounding relation about the tube. Each flange includes a centrally positioned aperture and a slit that extends through the flange from the aperture to an outer edge of the flange. The tube extends through the apertures of the flanges. Each flange includes a first edge portion that bounds a first side of the slit. Each flange includes a second edge portion that bounds a second side of the slit opposite the first side of the slit. The opposed first and second edge portions of each flange are bent such that the opposed first and second edge portions are orientated to extend outwardly from the tube at angles that are each acute in opposed directions with respect to the central longitudinal axis of the tube.

Abstract: In order to provide an exhaust muffler for an internal combustion engine, especially a portable implement, comprising a catalyst which is arranged in a housing which has at least one inlet opening and one outlet opening for exhaust gas flowing out from the internal combustion engine into the environment, in which the temperature of the exhaust gas in the area of the outlet into the environment is reduced substantially and/or a sufficiently long path length is made available so that flame development can be avoided especially in the outlet area of the exhaust muffler, it is proposed that the outlet opening has at least one means through which exhaust gas flows, which is arranged partially outside the housing and has an outlet facing the environment, whereby the flow path of the exhaust gas in the direction of the environment is lengthened.

Abstract: Devices are provided for regulating the pressure pulses and flow pulses that are emitted in the exhausts of apparatus and equipment such as internal combustion engines, compressors and poppet valves. The pressure pulses are reflected from a reflecting member to their source as expansion waves that create a reduced pressure zone that allows subsequently emitted flow pulses to be more easily emitted, thereby enhancing the operational efficiency of the apparatus and equipment. Flow pulses that contain exhaust products such as the products of combustion from an internal combustion engine are regulated so that the exhaust flow they generate is not unduly restricted within the device and an undesirable back pressure that resists the emission of flow pulses from their source created. In regulating the pressure and flow pulses, the devices attenuate the noise generated by the pressure and flow pulses.

Abstract: A fluid pathway is provided with a flow controller in at least a portion of its length wherein the flow controller comprises an active surface capable of influencing the fluid flow through the fluid pathway, the configuration of the active surface conforming to at least one logarithmic curve conforming to the Golden Section.

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 attenuation mechanism for an electronic device is presented. The attenuation mechanism includes an outer member that has an inner member oriented axially within the outer member. The inner member has an axial twist that causes a line of sight blockage between an exterior and an interior of a housing of an electronic device when the attenuation mechanism is mounted through the housing, such that sound and electromagnetic radiation is attenuated without obstructing cooling air that is flowing through the housing.

Abstract: The invention presents a sound dampening flow channel device defining at least one flow channel having an inlet opening and an outlet opening, the flow channel being at least partly delimited by at least one acoustic energy dissipative wall. The outlet opening of the flow channel cannot be seen from the inlet opening and vice versa. Preferably, the acoustic energy dissipative wall presents, in relation to the interior of the flow channel, a smooth curvature.

Abstract: A reactive acoustic dampener includes a nested three chambered configuration and connecting tubes that may be fully integrated into the fuel rail of a fuel injection system.

Abstract: A fuel cell system with a muffler to reduce noise generated while supplying air to a fuel cells disclosed. One embodiment of the fuel cell system includes an air feeder to supply air; an electric generator to generate electricity through an electrochemical reaction between air and fuel; and a muffler provided in one end of the air feeder. The muffler includes a first pipe and a second pipe which are different in length from each other. The muffler has a relatively small structure, so that limitation in a mounting space can be decreased and a more compact fuel cell system can be realized. Also, even if there are considerable noise components at two or more frequencies, the mufflers corresponding to the respective frequencies are connected in series, thereby reducing the noise.

Abstract: In order to provide an exhaust muffler for an internal combustion engine, especially a portable implement, comprising a catalyst which is arranged in a housing which has at least one inlet opening and one outlet opening for exhaust gas flowing out from the internal combustion engine into the environment, in which the temperature of the exhaust gas in the area of the outlet into the environment is reduced substantially and/or a sufficiently long path length is made available so that flame development can be avoided especially in the outlet area of the exhaust muffler, it is proposed that the outlet opening has at least one means through which exhaust gas flows, which is arranged partially outside the housing and has an outlet facing the environment, whereby the flow path of the exhaust gas in the direction of the environment is lengthened.

Abstract: An exhaust chamber system having a rotatable propeller type blade assembly at the entry to an expansion chamber which creates a vortex that swirls exhaust gas towards the outlet. The resultant action within the exhaust chamber aids in scavenging internal combustion engine exhaust gases, and in reducing system back pressure. The exhaust chamber maintains the sound level of the exhaust within acceptable limits while delivering improved horsepower, torque, and/or fuel efficiency over other known conventional mufflers.

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: The present invention provides an exhaust chamber system, comprising a stationary propeller type blade assembly with a nose cone within or adjacent to an expansion chamber, to create a vortex that swirls exhaust gas towards the outlet. The resultant vacuum within the exhaust chamber aids in scavenging an internal combustion engines exhaust gases, and in reducing system back pressure The exhaust chamber maintains the sound level of the exhaust within acceptable limits, while delivering improved horsepower, torque, and/or fuel efficiency over standard and other performance mufflers.

Abstract: An exhaust system baffling apparatus is provided. The apparatus includes a tube with at least one end that is not open. The apparatus further includes a plurality of C-shaped flanges in surrounding relation about the tube. The outer edges of the flanges have a contour which generally corresponds to a contour of an inner surface of a wall of an exhaust pipe. Opposed portions of the flanges adjacent the slits of the flanges are spread apart along the tube in a longitudinal direction. In addition, the opposed portions of the flanges adjacent the slits are angled in opposite directions and extend radially from the tube at a non-perpendicular angle with respect to the tube. At least two of the flanges include brackets adjacent the outer edges of the flanges, wherein the brackets are adapted for securing the apparatus to an interior portion of the exhaust pipe.

Abstract: There is disclosed a silencer for attenuating sound waves produced in a fluid that circulates through a fluid conveyer. The silencer comprises an expansion chamber that is in fluid communication with the fluid conveyer, and which carries sound waves there through; a sound wave dissipater provided with the expansion chamber and arranged to absorb sound waves traveling there through; a resonator operatively associated with the sound wave dissipater and constructed and arranged to cause attenuation and reflection of the sound waves back and forth towards the sound wave dissipater; the expansion chamber having a chamber: conveyer cross-sectional area ratio and chamber length characteristics allowing maximum transmission loss for a given frequency. The expansion chamber has an exit to allow fluid containing attenuated sound waves to escape therefrom.

Abstract: A muffler includes an inner passage residing in an outer shell, and a stationary fan residing in the inner passage. The fan creates a vortex in a flow through the inner passage thus improving the flow and reducing the exhaust sound level. The inner passage includes an inner passage shell and the fan comprises vanes extending inward from the inner passage shell and turned at approximately a 45 degree angle to a centerline of the inner passage. Pinch zones at the entrance and exit from the inner passage further reduce the exhaust sound level. The inner passage shell is preferably a perforated inner passage shell, and a sound deadening material resides between perforated inner passage shell and the outer shell.

Abstract: Exhaust passage control valve 10 may comprise housing 30, valve member 20, and helical torsion spring 40. Housing 30 has an exhaust passage. Exhaust gas from an internal combustion engine flows through the exhaust passage of the housing 30. Valve member 20 opens and closes the exhaust passage of the housing. Helical torsion spring 40 may be disposed at the opposite side of the valve member from the housing side thereof. Helical torsion spring 40 comprises a coil part wherein spring wires have been wound in a coil shape, and arms formed at both ends of the coil part. The coil part may be disposed at approximately the center of the valve member. When the arms bend with respect to the coil part, the counter-force of this bending energizes the valve member towards a closing side. The spring mounting member may be arranged and constructed to adjust a position in which the spring mounting member is mounted on the housing such that a rotation angle of the arms can be changed.

Abstract: A method is employed to attenuate ultrasonic noise propagating in a flow stream of a fluid flow system. In particular, the method attenuates the noise propagating between a noise source and a reference point in the flow stream (wherein the reference point and the noise source are positioned in the flow stream in direct acoustic line of sight relation). The method includes positioning an absorbent element in the flow stream between the noise source and the reference point. Then, the ultrasonic noise is directed past vicinity of the absorbent element such that indirect ultrasonic noise is absorbed by the absorbent element. Preferably, the method also includes deflecting the ultrasonic noise to convert direct noise to indirect noise prior to directing the ultrasonic noise past the vicinity of the absorbent material in the flow stream. Such a method may be employed to attenuate ultrasonic noise by up to about 20 dB to 45 dB.

Abstract: A method is employed to attenuate ultrasonic noise propagating in a flow stream of a fluid flow system. In particular, the method attenuates the noise propagating between a noise source and a reference point in the flow stream (wherein the reference point and the noise source are positioned in the flow stream in direct acoustic line of sight relation). The method includes positioning an absorbent element in the flow stream between the noise source and the reference point. Then, the ultrasonic noise is directed past vicinity of the absorbent element such that indirect ultrasonic noise is absorbed by the absorbent element. Preferably, the method also includes deflecting the ultrasonic noise to convert direct noise to indirect noise prior to directing the ultrasonic noise past the vicinity of the absorbent material in the flow stream. Such a method may be employed to attenuate ultrasonic noise by up to about 20 dB to 45 dB.

Abstract: A speaker enclosure including a compact quarter wavelength transmission path in the shape of a closed spiral that expands radially outward from a centrally located loudspeaker mounting location. The height of the transmission path has a minimum height that is equal to the height of the basket of the desired speaker. The quarter wavelength transmission path spiral of the provides an aerodynamic path for air flow therein which reduces the turbulence of air flow to a minimum that in turn provides even resistance to the air flow within the transmission line (Exhale vs. Inhale).

Abstract: A sound damping device (4) for a tubular duct (2), particularly a gas transporting tract of an internal combustion engine (1) having a least one bypass channel (5) running parallel to a main duct (6) in a section of the duct (2). The bypass channel (5) is longer than the main duct (6) between a branching off point (7) and a re-entry inlet (8). The bypass duct according to the invention is configured as a spiral duct (5) which winds around the centrally disposed main duct (6) in order to decrease the installation space requirements for the noise suppressor (4).

Abstract: A muffler has a housing (2) through which exhaust gas flows and which has at least one housing chamber (3, 5) and in which deflecting elements (13 to 16) serving to make the gas swirl are arranged spaced one behind another along a main axis (19?) of the housing in a positionally fixed manner. A disk-shaped body (17?) having guide vanes (18) with slots (18?) therebetween is provided as each deflecting element (13 to 16) and extends over the clear cross section of the housing (2). The guide vanes of adjacent disk-shaped bodies respectively deflect the flow in opposite directions about the main axis (19?) of the housing.

Abstract: A method is employed to attenuate ultrasonic noise propagating in a flow stream of a fluid flow system. In particular, the method attenuates the noise propagating between a noise source and a reference point in the flow stream (wherein the reference point and the noise source are positioned in the flow stream in direct acoustic line of sight relation). The method includes positioning an absorbent element in the flow stream between the noise source and the reference point. Then, the ultrasonic noise is directed past vicinity of the absorbent element such that indirect ultrasonic noise is absorbed by the absorbent element. Preferably, the method also includes deflecting the ultrasonic noise to convert direct noise to indirect noise prior to directing the ultrasonic noise past the vicinity of the absorbent material in the flow stream. Such a method may be employed to attenuate ultrasonic noise by up to about 20 dB to 45 dB.

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 system baffling apparatus is provided. The apparatus includes a tube with at least one end that is not open. The apparatus further includes a plurality of C-shaped flanges in surrounding relation about the tube. The outer edges of the flanges have a contour which generally corresponds to a contour of an inner surface of a wall of an exhaust pipe. Opposed portions of the flanges adjacent the slits of the flanges are spread apart along the tube in a longitudinal direction. In addition, the opposed portions of the flanges adjacent the slits are angled in opposite directions and extend radially from the tube at a non-perpendicular angle with respect to the tube. At least two of the flanges include brackets adjacent the outer edges of the flanges, wherein the brackets are adapted for securing the apparatus to an interior portion of the exhaust pipe.

Abstract: The invention relates to a muffler, particular for internal combustion engines, having a housing (2) trough which a flow medium flows and which has at least one housing chamber (3, 5) and in which deflecting elements (13 to 16) serving to make the flow medium swirl are arranged one behind another along a main axis (19′) of the housing and in a positionally fixed manner at a distance from one another, wherein a diskshaped body (17′) having slots (18′) is provided as deflecting element (13, 14, 15, 16) and extends over the clear cross section of the housing (2), and wherein guiding elements (18) which bound the slots (18′), are in the manner of guide vanes and belong to adjacent, diskshaped bodys (17′) deflect the flow in different directions with respect to the main axis (19′) of the housing.

Abstract: A silencer for connection to the air intake of a machine such as a turbocharger compressor. The silencer comprises a housing containing a plurality of axially spaced annular noise attenuating baffles. Each baffle has an outer circumference and an inner circumference defining a central aperture, the central apertures of each baffle collectively defining an axial outlet flow passage to an outlet aperture.

Abstract: A muffler for an internal combustion engine, capable of sufficiently attenuating exhaust sound and preventing power output from being reduced by allowing exhaust gas to flow without a hitch and generating vortices. The muffler comprises a casing, a vortex diffusing member, a vortex generating cylinder, and a vortex generating member. The vortex diffusing member is mounted in the casing and is connected to an exhaust inlet pipe. The vortex generating cylinder is positioned in the casing at its first side and is protruded into the exterior at its second side, and is provided with a tail pipe at its exterior end. The vortex generating member is axially mounted in the vortex generating cylinder.

Abstract: A submuffler for a vehicle muffler system which comprises a housing, a pressure-reducing conduit disposed within said housing, said pressure-reducing conduit containing a plurality of apertures disposed on the surface thereof, an eddy-generating member disposed within the pressure-reducing conduit along a substantial length thereof, and pipe means connected to an inlet side and an exit side of the housing for introducing exhaust gas thereto and exiting exhaust gas therefrom.

Abstract: A muffler has an elongated generally cylindrical casing having inlet and outlet ends, an elongated generally frustroconical baffle in the casing adjacent the inlet end with the smaller diameter portion being spaced from the inlet end. The peripheral wall of the baffle has closely spaced perforations over the major portion of its axial length and is spaced from the shell to provide a chamber thereabout. A generally cylindrical baffle has one end extending over the smaller diameter portion of the frustroconical baffle and has its peripheral wall spaced from the casing to provide a chamber thereabout. The peripheral wall of the cylindrical baffle has closely spaced perforations over most of its length. Exhaust gases enter the frustroconical baffle and exit through the perforations therein, move axially in the casing thereabout, and then pass through the apertures into the cylindrical baffle.

Abstract: A submuffler for a vehicle muffler system which comprises a housing, a pressure-reducing conduit disposed within said housing, said pressure-reducing conduit containing a plurality of apertures disposed on the surface thereof, an eddy-generating member disposed within the pressure-reducing conduit along a substantial length thereof, and pipe means connected to an inlet side and an exit side of the housing for introducing exhaust gas thereto and exiting exhaust gas therefrom.

Abstract: An exhaust pipe for motor vehicle muffler having a plurality of muffling holes arranged over the periphery, a partially perforated conical tube suspended on the inside and axially extended from the exhaust gas input end thereof for accelerating exhaust gas passing through, and a plurality of spiral portions formed integal with the periphery thereof and spaced around the conical tube for turning exhaust gas escaped from peripheral through holes on the conical tube into a spiral flow.

Abstract: A non-resonant pipe assembly comprised of two acoustical pipe paths in phase opposition. One pipe path by its physical presence will act as a half wave. The other pipe path is longer than the first by an odd integer multiple of the first path.

Abstract: A turbine exhaust structure is provided for a vehicle which includes an exhaust tail pipe having an inner wall defining a screw hole. The turbine exhaust structure includes a turbine exhaust device secured in the inner wall of the exhaust tail pipe, and a bolt co-operating with a nut for securing the turbine exhaust device in the inner wall of the exhaust tail pipe through the screw hole. The turbine exhaust device includes a housing secured in the inner wall of the exhaust tail pipe, a wheel disk secured in the housing, a plurality of catch pieces mounted in the wheel disk, an axle base secured in a central portion of the wheel disk, an axle rod rotatably mounted in the axle base of the wheel disk and having a first end provided with a first vane wheel and a second end provided with a second vane wheel, and two bearings mounted between the axle base and the axle rod.

Abstract: An exhaust passage control valve has a valve element of a spiral shape mounted on a valve seat portion of a housing through which exhaust gases from an engine pass. The valve element is urged by a valve spring in a direction of closing the valve. A spring constant of the valve spring is kept low without enlarging the valve spring, and there can be obtained opening and closing characteristics in that the valve opens at a stretch when an exhaust-gas pressure has reached a predetermined value. As the valve spring, a helical torsion spring having a coiled cylindrical body portion is used. Arm portions on both ends of a coiled cylindrical body portion are engaged with a pair of spring receiving members. The spring receiving members are disposed in the housing on circumferentially opposite sides of the valve seat portions. The arm portion are engaged with the spring receiving members so as to be slidable in a longitudinal direction of the arm portions.

Abstract: An exhaust muffler for a motor vehicle includes a louver tube having an intake end and an exhaust end. An outer tube, consisting of a frustoconical portion and a cylindrical portion, is concentrically arranged around the louver tube. A plurality of louvers and associated louver holes in the louver tube scoop a portion of gasses from the louver tube into the outer tube. An end cap, which includes an exhaust exit hole in its center, fits into an exhaust end of the outer tube. A plurality of end cap holes are arranged so that gasses leaving the outer tube flow through them. A restrictor disk between the end cap and louver tube includes a central hole coaxial with the louver tube and the exhaust exit hole of the end cap. Restrictor disk holes are in the restrictor disk between the central hole and its perimeter so that gasses leaving the louver tube flow through the central hole and the restrictor disk holes as they leave the muffler.