Abstract: A component of an exhaust system for an internal combustion engine comprises a wall in which at least one opening is provided. A perforated cover at least partly closes the at least one opening. The perforated cover is mounted on the wall using a holder, and a portion of the perforated cover engages into an opening provided on the holder. There is also presented an exhaust system comprising such a component, and a method for manufacturing such a component, in which the perforated cover is mounted on the holder by introducing at least one portion of the perforated cover into an opening provided on the holder.

Abstract: A silencer for vacuum pumps which allows only for unidirectional flow and which reduces the noises caused by the air discharged at the exhaust of said pump. The silencer features baffles to divert and disrupt the flow and an umbrella check valve to ensure the unidirectionality of the discharge flow.

Abstract: A silencer includes: a housing that has a draw-in portion drawing in fluid, and a plurality of sound attenuating portions arranged in a flowing direction of the fluid; a first partition provided with an intermediate communicating portion communicating the most downstream attenuating portion with the adjacent attenuating portion located adjacent to the most downstream attenuating portion; a valve portion disposed in the most downstream attenuating portion, the valve portion being capable of closing the intermediate communicating portion; a valve holding portion holding the valve portion, the valve holding portion being detachably attached to the housing; and a draw-out portion provided in a portion of the most downstream attenuating portion other than the valve holding portion, the draw-out portion drawing out the fluid from the most downstream attenuating portion.

Abstract: An exhaust device of an internal combustion engine for reducing exhaust sound and for suppressing the occurrence of a torque valley. A sound-deadening and pressure-dissipating device connected to the downstream end of an exhaust pipe includes a spherical member having an opening portion opening toward a downstream edge of the exhaust pipe. Exhaust gas from the exhaust pipe is reflected by an inner spherical surface of the spherical member to reduce exhaust pressure in the spherical member and then is discharged from the opening portion.

Abstract: An aircraft turbine engine with a takeoff fan speed and a landing fan speed, the aircraft engine includes a fan duct with a HQ (Herschel-Quincke) acoustic control noise reduction tube. The acoustic control noise reduction tube contains a movable frequency tuner obstruction. The movable frequency tuner obstruction is movable within the acoustic control noise reduction tube, with the movable frequency tuner obstruction movable along a fixed tube path length between a first takeoff frequency obstruction tube path location, and a second landing frequency obstruction tube path location, with the frequency tuner obstruction positioned at the first takeoff frequency location with the takeoff speed, and the frequency tuner obstruction positioned at the second landing frequency location with the landing speed to reduce noise.

Abstract: A selectively removable exhaust baffle which can be placed within an exhaust pipe to muffle the emitted sound. The removable baffle preferably includes a frame having a pair of legs joined by a spring portion. One or more transverse occluding plates are mounted on the frame. The frame is sized so that when it is pushed into the exhaust pipe it must be compressed. This compression holds the frame in place. The transverse occluding plate or plates lie against the interior wall of the exhaust pipe. The gas flow must therefore pass around the plate or plates, thereby attenuating the sound.

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 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: The invention uses tubes for the reduction of radiated duct noise. The tubes may be used to attenuate narrow band noise by diverting a portion of the acoustic energy through the tubes back into the duct. Upon reintroducing the diverted flow out of phase with the primary flow, acoustic cancellation is achieved. The frequency at which this occurs is dependent on the difference in the path lengths through the tubes and the separation distance—the distance separating the inlet and outlet of the tube. This invention can be used over varying frequency ranges by using an arrangement of flexible, constant length tubes. The effective frequency range is tailored by varying the separation distance and also allows the varying the angular arrangement of the tubes for more effective attenuation of spinning modes having varying propagation angle.

Abstract: An apparatus for transmitting sound in a motor vehicle having a housing (1) with an inner partition (2), which together define two separate subspaces (3, 4). A transmission valve (6) which separates the two subspaces (3, 4) is provided in a pivot bearing opening (9) in the partition (2) and is mounted to pivot about a pivot axis (5) in the area of the pivot bearing opening (9). The first subspace (3) is connected in a manner capable of transmitting sound to an intake manifold (17) of an internal combustion engine, and the second subspace (4) is connected in a manner capable of transmitting sound to an interior space of the motor vehicle. The gap (11) between an edge (10) of the pivot bearing opening (9) and the transmission valve (6) is sealed in a pressure-tight manner by a membrane (12).

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: 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: 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: An acoustic filter is provided with a single flow chamber for exposure of a flexible rubber layer to liquid undergoing flow through the flow chamber with noise producing acoustic energy therein. The flexible rubber layer is supported on a cylindrical drum with slanted holes therein through which the exposure to the liquid in the flow chamber is effected. An axially sectioned drum with dimensionally different diameters, radial thicknesses and slanted holes therein is positioned over the rubber layer within an outer casing to establish a plurality of gas-filled cavities of different axial lengths and separated from each other along the axial length of the liquid flow chamber which is connected at its opposite axial ends by pipe sections to a piping system from which the liquid within the flow chamber is derived.

Abstract: An in-line resonator for an air induction system of an internal combustion engine is provided. The system includes a resonator housing, an upstream duct, a downstream duct, a conduit, a partition, and a sleeve. The conduit extends through the resonator housing connecting the upstream duct and the downstream duct. The partition is moveable within the resonator housing and divides the housing into an upstream chamber and a downstream chamber. The downstream chamber, the conduit, and the downstream sleeve cooperate to form a first Helmholtz resonator that is in fluid communication with the downstream duct. The upstream chamber, the conduit, and the upstream sleeve cooperate to form a second Helmholtz resonator that is in fluid communication with the upstream duct. Further, a means is provided to axially move the partition to vary the volume of the chambers concurrently with the length and/or area of the passages.

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 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: In-line exhaust systems comprise an exhaust pipe, and a sound-attenuating baffle in the exhaust pipe. The baffle has one or more baffle plates extending across the gas flow channel, at least one at an oblique angle. Each plate has an array of apertures therethrough. The plates are joined to each other, preferably in edge-to-edge relationship, preferably forming included angles with each other and forming preferably different, oblique angles to the longitudinal axis. In preferred embodiments, plate aperture area increases, plate-to-plate, along the direction of advance of gases in the exhaust system. A backwash valve can lie over one of the baffle plates. The exhaust system can include a water jacket, and optionally an outer sound attenuation chamber. The baffle is preferably 36 or less inches long, the exhaust system reducing noise by at least 3 decibels.

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 secondary air injection system for reducing the hydrocarbon emissions of an internal combustion engine that is provided with an air pump supplying air to the exhaust manifold of the engine through a check valve assembly and an elastomeric hose characterized in that a baffle in the shape of a helix is located internally within the hose so as to cause the exhaust pressure waves from the engine and passing beyond the check valve assembly to impinge upon the solid compound surface of the baffle and be divided and diffused as they progress along spiraling paths so as to prevent objectionable noises being generated in the hose by the pressure waves.

Abstract: A motor vehicle muffler mounted with a plurality of baffles, the muffler comprising a variable control unit constructed such that at least one baffle in the muffler is moved to vary volumes of chambers according to a depression of an accelerator pedal, to obtain an optimum noise attenuation effect and to increase exhaust efficiency.

Abstract: An auto-adjusting damper assembly for an air muffler, such assembly including a spring loaded damper plate located above an outlet hole for transferring some of the energy of incoming air into a mechanical movement of such damper.

Abstract: A muffler responsive to exhaust flow rate is provided for an internal combustion engine. The muffler includes a body having a variable restrictor located downstream from an inlet port and upstream from an outlet port of the muffler. The variable restrictor includes a valving element with an operative position which varies as a function of engine exhaust flow rate to occlude exhaust gas flow. The variable restrictor is formed with a solid wall disposed about the valving element to define a constricting annular passageway having a cross section that varies with distance from the inlet port and from the outlet port. The passageway cross section for some mufflers will increase in a direction proceeding from the inlet port toward the outlet port, and will decrease proceeding in that same direction in other mufflers, depending upon the type of internal combustion engine employed.

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

Abstract: The invention relates to an exhaust silencer device for an internal combustion engine, for placement in the exhaust pipe of the engine. The device according to the invention comprises a damper plate disposed in the exhaust pipe and pivotably about a shaft substantially perpendicular to the longitudinal axis of the exhaust pipe between a closed position, in which the damper plate covers the major portion of the exhaust pipe flow area, and an open position, in which it permits substantially free flow through the exhaust pipe. An operating device is arranged to actuate the damper plate to adjust its position dependent on the exhaust flow through the exhaust pipe.

Abstract: This invention relates to a hydraulic device comprising at least one adjuble working, control or regulating member between a pressure source (3) and the flow path of an outlet (5,R), said member establishing an unrestricted connection to a passage in one position with the pressure medium which is present flowing out via said connection by expanding. In the case of high working pressures and/or great quantities of delivery, a loud noise develops in such hydraulic devices throughout the whole flow path of the outlet when the jet flows out.

Abstract: An engine exhaust accessory unit comprises a tubular housing adapted to be fitted over the end of an exhaust header. The outer end of the tubular housing is partially obstructed by a pivotable rigid perforated plate. The plate is pivotally mounted about a transverse axis offset below the central longitudinal axis of the housing. The larger upper section of the plate causes it to swing outward in response to passage of exhaust gases through the housing. The perforated plate automatically modifies engine noises and varies exhaust back pressure as a function of its angular position about the transverse axis. A yieldable spring biases the plate to a perpendicular position across the housing, and resists pivotal movement of the butterfly plate in response to passage of exhaust gases. Stops in the path of movement of the plate limit its movement between a perpendicular position across the housing and a position parallel to the longitudinal central housing axis.

Abstract: The muffler comprises a resonator (6) which communicates by way of an outlet orifice (14) with a chamber (5). A flexible valve member (16) regulates the section of the passage through this orifice in accordance with the rate of flow of the gas through the outlet of the resonator under the action, for example, of the pressure prevailing in the resonator. When the running speed of the engine decreases, the valve member reduces the section of the passage through the orifice (16) and modifies the acoustic attenuation in the resonator. The valve member may be controlled by other parameters of the flow of the exhaust gas inside the muffler.

Abstract: Noise reduction mechanism for an engine, especially effective during idling nd operation at low RPM, is disclosed. Under those conditions, engine exhaust noise often represents a predominant part of the total vehicle noise. The noise reducing mechanism comprises a flow-throttling element that substantially closes the main exhaust passage when the engine is in the low-speed range; the exhaust gas and noise is forced to flow through a more effective muffling device to reduce the noise at the exit end of the system. At high engine speeds, the throttling mechanism is deflected to a maximum flow condition for avoidance of undesired back pressure in the exhaust system.

Abstract: An exhaust muffler intended for noise dampening of, for instance, pneumatic tools, comprising a variable flow restricting passage, an attenuation chamber and a non-variable flow restricting passage. A valve body is arranged to control said variable flow restricting passage in response to the actual exhaust gas pressure. A movement dampening chamber, partly defined by the valve body, communicates with the atmosphere through a restriction opening to prevent resonance vibration of the valve body.