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: Disclosed is a silencer system configured to allow for thermal growth thereof while attenuating noise created by expansion of high-pressure fluid flowing therethrough. The silencer system comprises a tubular inner sleeve, a tubular flexible bellows, a tubular vent stack and a muffler disc. The inner sleeve has a sleeve inlet and a sleeve outlet. The inner sleeve is concentrically disposed in spaced relation within the bellows which is concentrically disposed in spaced relation within the vent stack. The bellows is configured to allow for axial and lateral movement of the inner sleeve relative to the vent stack when fluid passes through the silencer system to minimize excessive deflective forces and bending moments on the silencer system. The muffler disc is oriented relative to the sleeve outlet such that the high-pressure fluid impinges the muffler disc prior to creating shockwaves which may otherwise result in the production of high noise levels.

Abstract: A fan shroud includes a fan shroud portion having a surface including an aperture. A cooling fan is supported proximate to the aperture for permitting air flow through the fan shroud from the environment to the engine compartment. An air intake portion is supported on the fan shroud portion. The air intake portion and the fan shroud portion together define at least a portion of an air passageway having an inlet for receiving ambient air and an outlet for connection to an engine throttle. The fan shroud portion and air intake portion may respectively include first and second circumferential portions that define the air passageway.

Abstract: A noise muffler for the exhaust of waste gases from apparatus such as an oxygen concentrator, including a muffler core with an inlet to receive the waste gases and a plurality of bores in the core first to direct the waste gases through a filter material and a cap enclosing the filter material and forming a plurality of outlets to direct the waste gases out of the muffler, the bores and outlets positioned to cause the waste gases to change their direction of flow multiple times before exiting the muffler.

Abstract: Duct units for delivery of air to an air supply fan and for connecting this fan to an air heater unit are disclosed. The duct unit for delivering air in one version has a narrow first section, a second, transition-type section and a wide sound attenuating, third section with these three sections extending generally vertically. Spaced apart splitters containing sound attenuating material and having side walls of perforated metal are mounted in the third section. The splitters include a central splitter and outer splitters with the latter converging inwardly towards a central axis of the third section. This duct unit also has an elbow-shaped duct section connected to the third section at its upstream end and connectible to the fan at its downstream end. In another version, the duct unit has a single, elongate splitter that extends longitudinally along at least a major portion of a second duct section and that bends through a smooth curve.

Abstract: The present invention provides a noise attenuation assembly having at least one noise prevention pad disposed within an annular gap formed between a gas passage tube and an overlap tube. The noise prevention pad prevents the two tubes from coming in contact during thermal expansion of the tubes, and allows the tubes to contract without causing “tick and ping” noise, during a cool down.

Abstract: A compressed air muffler comprises a rear attachment section, a compressed air muffler section adjoining it in the longitudinal direction with a compressed air muffler body of a porous compressed air muffler material and an outlet duct extending in the length direction as far as a front outlet opening, such outlet duct having in the muffler section, a form tapering toward the outlet opening. The muffler body has a bare outer peripheral face, its outer periphery face constituting an outlet face for the compressed air flowing through its wall athwart the longitudinal direction. The duct section extending through the attachment section, of the outlet duct merges steplessly with the duct section running in the muffler section.

Abstract: A noise reduction system for significantly reducing the noise generated by an air turbine used to create suction for automatic cutting tables. The system employs one or more baffles mounted within a closed main housing including noise reduction foam and an exhaust housing lined with noise reduction foam mounted around the baffle exhaust. The direction of the exhaust air is changed 180 degrees and is utilized for cooling the air turbine and electric motor.

Abstract: An improved exhaust system for an internal combustion engine generally comprises two expanding megaphones, separated by a dual core annular flow silencing section. The two or split megaphone design facilitates broadening of the time of the negative pressure wave to provide a desirable broad range power output while substantially reducing obnoxious sound output.

Abstract: This engine muffler has a sound absorbing material interposed between an internal tube and an external tube which is formed with a projection projecting toward the sound absorbing material along almost its entire periphery. When interposing the sound absorbing material between the internal tube and the external tube and drawing the end of the external tube for manufacturing the muffler, the projection projecting toward the sound absorbing material is formed on the external tube almost along its entire periphery after inserting the sound absorbing material between the internal tube and the external tube but before drawing the end of the external tube.

Abstract: A resistive muffler attenuates sound generated by the gas intake and suction valve during compressor operation of a refrigerant compressor. The resistive muffler is assembled inline with the suction gas flow of the compressor and is positioned within the compressor housing. The resistive muffler attenuates the sound generated by the compressor during its operation as refrigerant gas is drawn into the compressor from an evaporator and passes through the resistive muffler in transit to the suction valve and hence to the region of the compressor where the gas is physically compressed. The resistive muffler includes a muffler housing having an intake end and an exhaust end. An acoustic foam assembly is incorporated into the muffler housing.

Abstract: An exhaust muffler for an internal combustion engine included in a motorcycle includes a perforated inner pipe (32), an outer pipe (31) coaxially surrounding the inner pipe (32), and a glass wool mat (33) packed in a space between the inner pipe (32) and the outer pipe (31). A three-layer protective structure is formed by winding an inner stainless steel wire mesh (34) wound around the inner pipe (32), winding a stainless steel wool mat (35) around the inner stainless steel wire mesh (934), and winding an outer stainless steel wire mesh (36) around the stainless steel wool mat (35). The glass wool mat (33) is wound around the three-layer structure. The three-layer structure extends the life of the glass wool mat (33) even if the temperature and pressure of the exhaust gas discharged by the internal combustion engine increase.

Abstract: A gas expansion silencer comprising an endpiece for being connected to a source of gas under pressure, and a low-pressure stage comprising two cylindrical portions respectively of smaller diameter and of larger diameter, the smaller-diameter portion being connected to the endpiece and the larger-diameter portion having gas outlet orifices, the low-pressure stage being entirely filled with a porous metal packing.

Abstract: A permeable port constituted by an aperture and a porous member for covering the aperture is provided in a part of an intake air passageway portion of an air intake apparatus. The permeable port is disposed in at least a part of a region between the central position of the whole length of an air intake duct and the central position of the whole length of the intake air passageway portion.

Abstract: An absorptive and reactive muffler includes an annular flow path for the gas with the center of the annulus having a plurality of resonators which are in open communication with the downstream end of the annular flow path and make up the reactive portion of the muffler. The flow path is at least partially lined by an absorptive material overlain by a perforate material and makes up the absorptive portion of the muffler.

Abstract: A high-performance exhaust silencer in which a shell wall includes a shell outer plate, a shell inner plate, and a damping material to be inserted therebetween. A space between the shell outer plate and shell inner plate of the exhaust silencer is narrowed and the shell outer plate and the shell inner plate will not interfere with each other. An outer shape of the exhaust silencer is small but the expansion chambers are large by providing an air space between the shell outer plate and the shell inner plate. For the above-mentioned damping material, a material obtained by stretchably weaving metal wire into mesh is used.

Abstract: An improved exhaust system for an internal combustion engine generally comprises two expanding megaphones, separated by a dual core annular flow silencing section. The two or split megaphone design facilitates broadening of the time of the negative pressure wave to provide a desirable broad range power output while substantially reducing obnoxious sound output.

Abstract: The present invention provides a noise attenuation assembly having at least one noise prevention pad disposed within an annular gap formed between a gas passage tube and an overlap tube. The noise prevention pad prevents the two tubes from becoming in contact during thermal expansion of the tubes, and allows the tubes to contract without causing “Tick and Ping” noise, during a cool down.

Abstract: A muffler includes a tubular body having an interior surface extending between a first end and an opposing second end, the interior surface bounding a chamber. An exhaust cap is disposed on the second end of the tubular body, the exhaust cap having an interior surface bounding a channel that communicates with the chamber. An inlet cap is disposed on the first end of the tubular body. A perf tube is longitudinally disposed within the chamber of the tubular body. A spark arrestor includes a tubular neck advanced within the channel of the exhaust cap toward the body. A spark barrier is mounted on an end of the tubular neck so as to be at least partially disposed within the perf tube, the spark barrier being comprised of a sheet of mesh or porous material.

Abstract: A muffler includes an annular flow path for the gas with the center of the annulus having a plurality of resonators which are in open communication with the downstream end of the annular flow path. The flow path is at least partially lined by an absorptive material overlain by a perforate material.

Abstract: An exhaust muffler for a fuel-operated heating device has upper and lower housing half shells, an exhaust gas through-duct and absorption and reflection chambers. The exhaust muffler is connectable to an exhaust pipe of the heating device. The exhaust gas through-duct has an inlet pipe of a single absorption chamber and a single following reflection chamber that are separated by a partially perforated partition, with double reversal of the exhaust gas flow, and an outlet pipe; the inlet pipe being perforated on the outer surface side, with an S-shaped curved section and a straight end section, and the outlet pipe being a straight outlet pipe, closed on the outer surface side, and the straight section of the inlet pipe runs parallel to, and at a spacing from, an inlet section of the outlet pipe.

Abstract: A multi-duct diffusion exhaust device for a turbomachine. The exhaust device including an annular inlet, an outer casing shaped symmetrically overall with respect to an axis, one or more internal partitions defining several roughly concentric ducts for an exhaust stream to flow through, and an absorbent coating capable of absorbing some of the acoustic energy generated by the flow. The absorbent coating being provided on at least one of a surface of one internal partition and an interior surface of the outer casing. The absorbent coating having a thickness that is tailored along a length of the exhaust device to optimize the flow in the ducts by maintaining progressive diffusion and avoiding detachment near stationary surfaces.

Abstract: The current invention is device for lowering the air velocity and inherent noise of high-speed air released from a closed system, comprising a straight pipe module with an outer tube and a concentric inner tube creating an annular space therebetween. The inner tube has interior fins at the inlet, which initiate rotation in an airflow directed therethrough, and interior fins at the outlet, which arrest the airflow rotation. Perforations along the length of the inner tube, from inlet fins to outlet fins, permit the release of a turbulent outer zone of the airflow, permitting the high velocity core of the airflow to expand and slow, reducing the noise of the airflow.

Abstract: A muffler is provided for use in a pneumatic hand tool having a handle with an exhaust passage. The muffler includes an inner tube, an outer tube, an upper plate, and an end cap. The inner tube is located within the outer tube, with one or more openings being provided in each. The upper plate is located near the inner tube and is provided to close off the exhaust passage so that a majority of the exhaust air is directed into the inner tube during use. The end cap attaches to the handle for closing off the exhaust passage, but for one or more exit openings. During use, exhaust air enters the inner tube, flows out its penguins, flows out the outer tube openings, and flows out the exit opening in the end cap. The tortuous path slows the exhaust air and assists in dampening exhaust noise.

Abstract: A noise reduction system reduces noise associated with an input signal provided to a control system, while substantially minimizing the adverse affect on the responsiveness and stability of the control system. The noise reduction system includes a processor, a memory subsystem and processor executable code. The processor executable code causes the processor to perform a number of steps. Initially, the processor determines an input signal level of an input signal at an input of a noise reduction system. Next, the processor determines an output signal level of an output signal at an output of the noise reduction system. The processor then determines a magnitude of a difference signal which is the difference between the input signal level and the output signal level. When the magnitude of the difference signal is less than a predetermined noise limit, the input signal is provided to an input of a control system.

Abstract: The present invention includes a power booster pipe suitable for attenuating sound associated with the intake or exhaust of an internal combustion engine and reducing pressure drop associated with movement of gases during operation of the engine. Generally, a diffuser portion is combined with an attenuation portion. One or more tubes of perforated material, such as steel and perforated flutes running the length of the tube increases the surface area of sound attenuating material exposed to combustion gases and the accompanying noise. The perforated flutes and tube can be encircled with sound reducing infill material. A low pressure drop design can be incorporated which includes a gradually increasing diameter tube utilized to route the combustion gases.

Abstract: An auxiliary silencer system for connection with the exhaust system of an all terrain vehicle includes a fiberglass packed flow through silencer having a rigid elbow connected with the existing tail pipe and positioned by adjustable brackets transversely on the vehicle in alignment with the existing system.

Abstract: An improved sound attenuating device for use in a gas transportation duct, said device comprising a core of acoustically absorptive material substantially enclosed within an impervious film to prevent direct contact between the acoustically absorptive material and gas flowing through said gas transportation duct, wherein said enclosed absorptive material is maintained in position between at least two perforated facing plates and further wherein there is provided between the perforated facing and the impervious film and between the impervious film and the acoustically absorptive material spacing means to allow unrestricted movement of the impervious film in the void between the perforated facing and the acoustically absorptive material, while preventing contact between the film and the perforated facing and between the film and the acoustically absorptive material, and blocking means to impede the internal flow of gas between the film and the perforated facing and between the film and the acoustically absorpti

Abstract: A process is provided for filling a muffler shell with fibrous material. It comprises the step of providing a muffler shell comprising one or more muffler shell outer parts which define an internal cavity and an internal structure adapted to extend at least part way through the shell internal cavity and having one or more openings adapted to communicate with the shell internal cavity. The process further comprises the step of providing a bag filled with fibrous material. The bag has a first side with one or more first perforations defining a first side total open area and a second side with either no perforations or one or more second perforations defining a second side total open area. The first open area is greater than the second open area.

Abstract: An exhaust pipe has a manifold; one end of the manifold is connected to a distal end of a connecting tube. Another ends of the manifold are extended with a left branch tube and a right branch tube. The left branch tube is connected to a first muffler tube and the right branch tube is connected to a second muffler tube. The feature is that an interior of a middle section of the manifold has a valve which is controlled by a controller. The valve controls the area of the opening of the left branch tube communicated with the first muffler tube and the area of the opening of the right branch tube communicated with the second muffler tube. The driver may control the variation of exhaust gas without needing to adjust the exhaust pipe. The noise may be reduced easily and the performance of acceleration is enhanced.

Abstract: An insert assembly for a muffler of a high-performance motor cycle, having an insert with a filling of compressed heat-resistant, sound-absorbing material mounted on a removable hollow tube having an inside diameter greater than the outside diameter of the perforated core of the muffler. The filling includes a bulked-up continuous filamentary material. Once the insert has been introduced into the muffler by sliding the tube along the core, the tube is then withdrawn leaving the insert behind in the muffler. Removal of the tube allows the filling to relax towards its intended density. The first subsequent exposure to hot exhaust gases causes certain portions of the insert to degrade, allowing further relaxation of the filling to assume its intended density. Further, the tube precludes potential damage to the insert during its introduction into the muffler.

Abstract: A process is provided for filling a muffler shell with fibrous material. The process involves providing a muffler shell comprising first and second muffler shell outer parts which define an internal cavity when coupled together and an internal structure adapted to extend at least part way through the shell internal cavity and having one or more openings communicating with the shell internal cavity.

Abstract: A centrifugal blower capable of reducing noise. The centrifugal blower comprises an impeller having a hub plate and a set of blades disposed on at least one surface of the hub plate so as to surround an axis of rotation; and a casing surrounding the impeller and having a volute portion disposed at an outer peripheral portion thereof. The portion of casing facing the set of blades is formed with a plurality of through holes, whereas a sound absorbing material is attached thereto so as to cover the through holes. The noise caused by a compression wave of air occurring between the blades of impeller and the inner face of casing is efficiently absorbed by a sound absorbing material disposed adjacent the blades.

Abstract: An exhaust pipe includes an outer pipe and an inner pipe firmly fitted in the outer pipe. An air intake pipe and an outlet pipe having a comparatively small diameter are positioned respectively at two opposite ends of the outer pipe and respectively communicating with the front and the rear end of the inner pipe. Besides, a great number of through holes are bored around the wall of the inner pipe. Then an intermediate pipe having numerous through holes around the wall is fitted around the inner pipe, with a plurality of gaps formed between both the pipes. The muffling cotton is filled in a space between the outer pipe and the intermediate pipe. Thus, the intermediate pipe is easy to assemble, kept secured firmly for a long time and achieving effectual muffling.

Abstract: A multiple layer fiber filled sound absorber and method of manufacturing the absorber are disclosed. The sound absorber includes an outer housing, a porous or perforated inner tube or housing defining a passageway through which a gas may flow, and two layers of sound absorbing material, such as fiberglass wool, is positioned between the housings. The sound absorbing material adjacent the inner housing is selected to be more heat resistant than the material farther away from the inner housing. The sound absorber is filled with the sound absorbing materials using a direct fill process in which continuous fibers are injected into the sound absorber. In preparation for filling, a partition is positioned between the housings to define two chambers. Each chamber is filled with one of the sound absorbing materials. The partition may then be removed from the sound absorber, or may be left in place (in which case the partition is preferably porous or perforated).

Abstract: A silencer (10) includes a polymeric casing (12) spaced from at least one inlet pipe and at least one outlet pipe by polymeric spacers (52). The polymeric spacers are made from a different material to that of the polymeric casing. The polymeric spacers are heat-resistant and have a higher melting point than the polymeric casing. The polymeric spacers are made of a softer material than the polymeric casing, and the polymeric spacers are capable of being deformed to accommodate irregularities in the shape of the inlet and outlet pipes.

Abstract: A process is provided for filling a muffler shell with fibrous material. It comprises the step of providing a muffler shell comprising one or more muffler shell outer parts which define an internal cavity and an internal structure adapted to extend at least part way through the shell internal cavity and having one or more openings adapted to communicate with the shell internal cavity. The process further comprises the step of providing a bag filled with fibrous material. The bag has a first side with one or more first perforations defining a first side total open area and a second side with either no perforations or one or more second perforations defining a second side total open area. The first open area is greater than the second open area.

Abstract: A process is provided for filling a muffler shell with fibrous material. The process involves providing a muffler shell comprising first and second muffler shell outer parts which define an internal cavity when coupled together and an internal structure adapted to extend at least part way through the shell internal cavity and having one or more openings communicating with the shell internal cavity.

Abstract: An exhaust pipe includes an outer pipe and an inner pipe firmly fitted in the outer pipe. An air intake pipe and an outlet pipe having a comparatively small diameter are positioned respectively at two opposite ends of the outer pipe and respectively communicating with the front and the rear end of the inner pipe. Besides, a great number of through holes are bored around the wall of the inner pipe. Then an intermediate pipe having numerous through holes around the wall is fitted around the inner pipe, with a plurality of gaps formed between both the pipes. The muffling cotton is filled in a space between the outer pipe and the intermediate pipe. Thus, the intermediate pipe is easy to assemble, kept secured firmly for a long time and achieving effectual muffling.

Abstract: An adjustable muffler system for a combustible engine including a muffler adapted for connection with an exhaust pipe of an engine, a blocking tube configured to be removably inserted within the muffler, and latch means adapted to removably secure the blocking tube within the muffler. In other embodiments, the blocking tube can include various holes or slots and may be telescoping or fabricated from multiple pieces.

Abstract: An exhaust muffler for an internal combustion engine included in a motorcycle includes a perforated inner pipe (32), an outer pipe (31) coaxially surrounding the inner pipe (32), and a glass wool mat (33) packed in a space between the inner pipe (32) and the outer pipe (31). A three-layer protective structure is formed by winding an inner stainless steel wire mesh (34) wound around the inner pipe (32), winding a stainless steel wool mat (35) around the inner stainless steel wire mesh (934), and winding an outer stainless steel wire mesh (36) around the stainless steel wool mat (35). The glass wool mat (33) is wound around the three-layer structure. The three-layer structure extends the life of the glass wool mat (33) even if the temperature and pressure of the exhaust gas discharged by the internal combustion engine increase.

Abstract: A silencer for internal combustion engines provides a form factor of a rectangular prism, and includes a box-shaped outer shell lined with a thermal and acoustic isolation material, and containing a set of acoustic elements in a serpentine path inside that layer.

Abstract: An engine muffler and spark arrestor includes an outer tube extending along an axis and having an inlet end and an outlet end. A plurality of substantially identical nested discs are disposed coaxially adjacent the outlet end of the outer tube. Each of the discs has a centrally located aperture. Each of the discs also has at least one slot extending therethrough. An end cap is disposed on a distal end of the set of discs. The end cap has a solid central portion which forces at least a portion of an exhaust gas flowing from an internal combustion to which the muffler is connected to flow radially outwardly along interstitial spaces defined between each pair of discs and then flow axially in a direction approximately parallel to a longitudinal axis of the muffler.

Abstract: In order to provide a sound absorbing material superior in acid resistance, alkali resistance and sound absorbing quality and a sound absorbing layer using this sound absorbing material, multiple pieces of basalt yarn obtained by dissolving basalt to be continuous fibers are bundled by a fiber bundling agent to acquire a bundled material, and the bundled material is fibrillated to obtain a bulky sound absorbing material. Moreover, the sound absorbing material is arranged on the outer periphery of a perforated pipe constituting a muffler to form a sound absorbing layer.

Abstract: A sound attenuating device including a sound insulating structure and a windband. The sound insulating structure is constructed and arranged to receive vented air from an exhaust vent. The windband is affixed to the sound insulating structure and is constructed and arranged to prevent water from entering the sound insulating structure. The windband also provides a structure for attenuating sound.

Abstract: The present invention discloses an improved structure of a muffler at the rear end of an exhaust pipe, mainly comprising a tapered inner pipe inside a tapered conical outer pipe, and a plurality of silencing holes being disposed on the wall of the inner pipe, and a silencing cotton wrappers around and covers the external rim of the inner pipe, and a sleeve being disposed in the inner pipe proximate to the rear end of the inner pipe. The front end of such sleeve is a tapered conical pipe, and the rear end slight extends to the outside of the rear end of the external pipe. A decorative lid covers the rear end surface of the external pipe, and a gas-receiving pipe having a French connector being soldered to the front end of the external pipe, and an n-shaped fixing bracket having a fixing hole on it being soldered to an appropriate position on the external surface of the external pipe proximate to the rear end.

Abstract: A process is provided for filling a muffler shell with fibrous material. The process comprises the steps of: providing a muffler shell comprising first and second muffler shell outer parts which define an internal cavity when coupled together and an internal structure adapted to extend at least part way through the shell internal cavity for defining at least one channel having one or more openings communicating with the shell internal cavity; placing a form over at least one of the internal structure and the first muffler shell part; drawing a partial vacuum through a first end of the channel; feeding fibrous material into the form while drawing a partial vacuum through the channel; removing the form after the fibrous material feeding step; and positioning the second muffler shell part over at least one of the internal structure and the first muffler shell part.

Abstract: A process is provided for filling a muffler shell with fibrous material. The process comprises the steps of: providing a muffler shell comprising first and second muffler shell outer parts which define an internal cavity when coupled together and an internal structure adapted to extend at least part way through the shell internal cavity for defining at least one channel having one or more openings communicating with the shell internal cavity; placing a form over at least one of the internal structure and the first muffler shell part; drawing a partial vacuum through a first end of the channel; feeding fibrous material into the form while drawing a partial vacuum through the channel; removing the form after the fibrous material feeding step; and positioning the second muffler shell part over at least one of the internal structure and the first muffler shell part.

Abstract: A motor vehicle muffler having a muffler loop installed in a casing in the exhaust pipe of a motor vehicle, the muffler loop formed of three muffler tubes and two connecting tubes, the muffler tubes being arranged at different elevations in the casing and crossed by one another at the same point, the connecting tubes being arranged in parallel outside the casing to connect the muffler tubes in series.

Abstract: This invention relates to a muffler to be used in the exhaust system of an engine for automobiles, specifically to a muffler including a sound absorbing material interposed between the external tube and the internal tube, and a method of manufacturing the same. There are provided a durable and easy-to-manufacture engine muffler in which the sound absorbing material is reliably secured during use and during manufacturing process, and a method of manufacturing the same. The engine muffler comprising a sound absorbing material interposed between an internal tube and an external tube is formed with a projection projecting toward the sound absorbing material on the external tube along almost entire periphery thereof.