Abstract: A powertrain control system is provided that includes an engine having multiple cylinders. A controller selectively activates the cylinders to provide a cylinder combination having a desired power displacement. In one example powertrain control system, the controller selectively activates the cylinders between a V-8 and V-4 mode. An exhaust system having a valve and an electrical actuator selectively electrically actuates the valve in response to the controller between multiple positions. The electrical actuator moves the valve from an open position in V-8 mode to a partially closed position in V-4 mode to increase back pressure and reduce NVH issues in V-4 mode. A muffler includes a housing having an exhaust passage. The valve is supported by the housing and arranged in the exhaust passage. The valve is moveable between multiple positions for tuning the muffler. The electrical actuator is supported by the housing to actuate the valve between the multiple positions.

Abstract: An exhaust gas control valve includes a valve seat, a valve plate having a first exhaust gas pressure receiving area corresponding to an opening area and a second exhaust gas pressure receiving area larger than the first area; and a spring for closing the valve. In a closed state, gas pressure during a low engine speed operation acts on only the first exhaust area for shutting the opening. In an intermediate state, the pressure during a the middle engine speed operation acts on the first and second areas for opening the opening but closing the valve by overlap of wall portions of the valve plate and the valve seat overlap. In an opening state, the pressure during a high engine speed operation acts on the first and second areas for forming a gap between the wall portions to pass the gas therethrough.

Abstract: A passive, exhaust pressure actuated valve assembly for placement inside a tubular exhaust conduit is pivotally mounted to an off-center axle for rotation between fully closed and fully opened positions. A bias element forces the valve flap toward the fully closed position. The valve flap is shaped in a manner enabling use of the interior surface of the exhaust conduit to define stops at the full closed and full opened positions. The valve flap shape, in conjunction with the bias element arrangement, enables the flap to lie substantially parallel to a longitudinal axis of the conduit in the fully opened position, which provides for minimum back pressure in the conduit. The valve assembly finds particularly advantageous use inside a bypass through pipe of a muffler assembly.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise (730) comprises: (1) at least one tube “H-Q” having an inlet end (738), an outlet end (740) and a central tube portion therebetween; an (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one tube having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.

Abstract: A noise control apparatus for a motorcycle exhaust system. The apparatus includes at least one exhaust pipe assembly having a direct pass-through mode and an indirect mode wherein exhaust gases are optionally directed through noise attenuating means. The apparatus includes at least one valve for controlling exhaust gas flow, a motor, a switch controlling said motor, a wire carrier, a wire connected between the carrier and the valve(s), and a rotary threaded drive shaft driven by the motor for moving the positioner. The threaded drive shaft includes radially extending and circumferentially facing stop means on both sides of said wire carrier. The valve is positioned under the control of the switch.

Abstract: The invention concerns diesel particulate filter regeneration in an exhaust system of a vehicle having a diesel engine. The particulate filter regeneration is selectively accomplished by actuating a particulate filter backpressure valve located downstream of the diesel particulate filter. Exhaust noise is attenuated for both normal driving and regeneration modes of operation by directing the exhaust flow through different flow paths in a muffler downstream of the diesel particulate filter.

Abstract: The invention concerns an internal combustion engine exhaust line comprising an active noise reduction system with variable choke device, continuously regulated based on the instantaneous discharge rate pulses of exhaust gases exiting from the internal combustion engine, including an expansion chamber for closing phases of the variable choke device arranged upstream of said active noise reduction system and a cavity dispersing medium and high frequencies arranged downstream of the active noise reduction system. The expansion chamber for the closing phases of the variable choke device is integrated in a first depolluting system arranged upstream of said active noise reduction system.

Abstract: To provide a motorcycle exhaust system, which is less susceptible to the elevated temperature of the exhaust gases and vibrations induced by the motorcycle combustion engine (E) and in which the sectional area of the exhaust passage can be properly adjusted independence on the operating condition of the motorcycle combustion engine (E), the motorcycle exhaust system includes a motorcycle combustion engine (E) mounted at a location generally intermediate between front and rear wheels (3 and 9), an exhaust passage fluidly connected at one end with an exhaust port of the motorcycle combustion engine (E), a silencer (17) fluidly connected with the opposite end of the exhaust passage and supported by the motorcycle frame structure (FR) at a location generally above the rear wheel (9); and an exhaust control valve (24) disposed in an inlet of the silencer (17) for variably adjusting the sectional area of the exhaust passage.

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 device for active noise reduction has a chamber, which is arranged laterally in relation to a gas flow, and a chamber opening constructed in one wall of the chamber. In the area of the chamber opening, a deflection device is adjustably arranged. The deflection device, in a first position, at least partially directs the gas flow running by the chamber opening into the chamber, in order to compress air there, and, in a second position, directs the gas from the chamber to the gas flow, in order to release the gas inside the chamber. The resulting alternating pressure inside the chamber is radiated through the chamber opening as sound and overlays the disturbing sound.

Abstract: A flapper finger valve assembly for use in an exhaust system. The flapper finger valve includes a tube having a plurality of orifices therethrough. The flapper finger valve assembly also includes a plurality of flapper finger valves generally having a C-shape wherein the flapper finger valves are arranged on an outside surface of the tube. The flapper finger valves are capable of radial movement with respect to the tube. A plurality of retainers generally having a C-shape are arranged around the flapper finger valve. These retainers will define a maximum radial movement for such flapper finger valves on the tube. The flapper finger valve assembly also includes a fastener which will secure the flapper finger valves between a tube and retainers in the flapper finger valve assembly.

Abstract: A muffler with variable acoustic properties. A pressure cell with a diaphragm, a spring, a piston, a piston rod, a closing element on the piston rod, and a pressure connection line are integrated into a housing. The diaphragm is thermally insulated against the piston rod. Another layer of thermal insulation is provided between the closing element and the pressure cell.

Abstract: A system for attenuating exhaust noise from an engine with a first group of active cylinders and a second group of deactivatable cylinders includes a first exhaust manifold connected to the first group of active cylinders and a second exhaust manifold connected to the second group of deactivatable cylinders. The second exhaust manifold is connected to the first exhaust manifold such that the second exhaust manifold acts as a resonator to attenuate sound from the first group of active cylinders when the second group of cylinders is deactivated.

Abstract: A valve device for a silence opens a bypass passage provided in the silencer to flow exhaust gas through the bypass passage when exhaust gas pressure rises to a certain pressure. The valve device includes a base having a valve opening through which exhaust gas flows, and a plate-like valve for opening and closing the valve opening. The plate-like valve is fixed to the base at its proximal portion, and is bent at both edges thereof in a certain range extending from its distal end toward the proximal portion.

Abstract: Exhaust system assemblies employ wire bushings for thermal compensation to minimize noise due to “stick-slip” while the system cools. In a preferred embodiment, the wire bushings are formed of at least one strand of wire coiled about male end portions of pipe sections used in the system, each of which male end portions are inserted into a female end portion and held therein by an interference fit. The strand of wire is spot welded at spaced locations to the male end portions to provide bearing surfaces between the spot welds that move slightly as the exhaust system heats and cools to relieve thermal stress in small, substantially inaudible increments.

Abstract: In a muffler device of a motor vehicle, with a plurality of mufflers and an actuator for changing the flow resistance to the exhaust gases flowing through the mufflers, in order to change the damping characteristic, the actuator is provided in a pipe branch having an inlet and two outlets, each outlet being connected via a pipe to a muffler, and the throughflow cross section of the inlet being variable by means of the actuator.

Abstract: An exhaust gas system for an internal combustion engine, in particular, of a motor vehicle has two mufflers through which the exhaust gas is able to flow in a parallel fashion. A switching unit makes it possible to selectively convey the exhaust gas flow of the internal combustion engine only or almost exclusively through the first muffler, or only or almost exclusively through the second muffler, or through both mufflers in a parallel fashion. The two mufflers are realized differently with respect to their muffling effect and/or flow resistance.

Abstract: A flapper finger valve assembly for use in an exhaust system. The flapper finger valve includes a tube having a plurality of orifices therethrough. The flapper finger valve assembly also includes a plurality of flapper finger valves generally having a C-shape wherein the flapper finger valves are arranged on an outside surface of the tube. The flapper finger valves are capable of radial movement with respect to the tube. A plurality of retainers generally having a C-shape are arranged around the flapper finger valve. These retainers will define a maximum radial movement for such flapper finger valves on the tube. The flapper finger valve assembly also includes a fastener which will secure the flapper finger valves between a tube and retainers in the flapper finger valve assembly.

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

Abstract: An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.

Abstract: A bypass for an exhaust system for a utility vehicle, such as a combine, that, when substantially closed, provides maximum noise attenuation for road transport, i.e., relatively high back pressure, and then, when substantially open, would provide a reduced flow restriction, i.e., relatively low back pressure, for full power, field operation. A bypass flow path in an exhaust pipe is located upstream of a primary muffler. A diaphragm can be provided to manipulate a damper which acts to close the exhaust flow to the primary muffler and open the bypass to an exhaust pipe to effectively bypass the primary muffler.

Abstract: A device for silencing a flowing gas which includes a valve housing in which a valve is mounted. A separate pressure regulator is provided which is in communication with the flowing gas and which is responsive to gas pressure to thereby influence movement of a mechanical actuating device which controls movement of the valve such that the valve may be opened at least two different rates dependent upon the pressure of the flowing gas.

Abstract: The invention concerns an exhaust silencer arrangement with integrated bypass assembly and external actuator to control the position of the bypass assembly. For applications where a heightened loudness, or increased horsepower through the decrease of exhaust noise suppression is desired or required, but at temporary instances, the invention allows for real time electronic control over the loudness and horsepower potential of the internal combustion engine to which it is applied. The invention is comprised of the exhaust muffler with integrated bypass and silencer module, external electronic actuator, and the mechanical cable which transmits the mechanical output of the actuator to the bypass valve of the exhaust muffler assembly. The exhaust muffler is comprised of the housing which contains the bypass tube and valve assembly, silencer module, and inlet and outlet chambers which intersect the bypass assembly with the silencer module.

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: The invention concerns an exhaust silencer arrangement with integrated bypass assembly and external actuator to control the position of the bypass assembly. For applications where a heightened loudness, or increased horsepower through the decrease of exhaust noise suppression is desired or required, but at temporary instances, the invention allows for real time electronic control over the loudness and horsepower potential of the internal combustion engine to which it is applied. The invention is comprised of the exhaust muffler with integrated bypass and silencer module, external electronic actuator, and the mechanical cable which transmits the mechanical output of the actuator to the bypass valve of the exhaust muffler assembly. The exhaust muffler is comprised of the housing which contains the bypass tube and valve assembly, silencer module, and inlet and outlet chambers which intersect the bypass assembly with the silencer module.

Abstract: An easily controlled exhaust tube 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 directly connected to an outer tube of a first noise eliminating tube and the right branch tube is connected to an inner tube of a second noise eliminating tube which has a valve seat. The left and right branch tubes are enclosed by outer tubes. Glass fibers and stainless steel and cotton structure are filled in the outer tube. A connecting piece is welded between the first and second noise eliminating tubes. A valve is installed in the valve seat. A front and a rear sides of the valve seat have respective washers. The valve is controlled by a controller.

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

Abstract: A partitioning member for dividing a connecting pipe into at least two exhaust passageways is provided in the connecting pipe, which is attached to an exhaust side of a silencer. A valve mechanism is operable to vary the passageway area of one of the exhaust passageways. With this structure, for example, when an engine is rotating at low revs, exhaust gas is discharged from the exhaust passageway without the valve mechanism, while when the engine is rotating at high revs exhaust gas is simultaneously discharged from the exhaust passageway having no valve mechanism and a passageway provided with the valve mechanism. Therefore, it is possible to reduce exhaust noise when the engine is rotating at low revs.

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

Abstract: In a muffler device (1) of a motor vehicle, with mufflers (2, 3) and actuator (4) for changing the flow resistance to the exhaust gases flowing through, in order to change the damping characteristic, it is proposed to provide the actuator (4) in a flow branch (5) having an inlet (6) and two outlets (7, 8), each outlet (7 or 8) being connected via a pipe (9 or 10) to a muffler (2 or 3), and the throughflow cross section (D) of the inlet (6) being variable by means of the actuator.

Abstract: A method and system for attenuating noise including arranging a plurality of accumulators (210, 310) to form a transmittance path for compressible flow mass and noise between a noise source (212, 312) and the external environment (218, 318), and selectively accumulating and confining compressible flow mass and noise within at least one of the plurality of accumulators, and attenuating noise confined within the at least one accumulator by ringdown. The system may include a plurality of interruptors/valves (220, 320) which are operated at respective timings for periodically accumulating and confining compressible flow mass and noise in at least one of the plurality of accumulators.

Abstract: An exhaust gas muffler for an internal combustion engine is provided, especially for a portable implement. The muffler has a housing with at least two parts, an inlet for exhaust gas issuing from the engine, and an outlet for discharge of processed exhaust gas. A partition is disposed within the housing between the inlet and outlet and divides the housing into two chambers. The partition is provided with a first opening in which a catalyzer is mounted, and at least one bypass opening. The muffler also has a respective valve member for each bypass opening. Below a specified temperature the bypass opening is closed. The valve member is controlled by the temperature in the muffler in such a way that when a prescribed operating temperature is exceeded, the bypass opening is opened.

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 gas cooling system for a vehicle includes a cooling fin system retrofit and a side exhaust pipe retrofit having an exhaust gas exit pipe having a first portion having a plurality of mixing portions which are either bends or internal mixing fins configured to mix vehicle exhaust gas, but not to restrict exhaust gas flow, a second portion fastened to the first portion and a chrome coated third portion fastened to the second portion and extending along the side of the vehicle. The cooling fin system retrofit includes an adjustable clamp and one or more cooling fins, each cooling fin having a base having a pair of upstanding arms, with one arm of the pair having a lip for engaging an arm of another cooling fin. An exhaust gas cooling system kit, a side exhaust pipe retrofit kit, a cooling fin kit are included.

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

Abstract: An exhaust assembly for use with a motor vehicle having a combustion engine. The exhaust assembly includes an exhaust and a muffler having first and second gas flow routes. A control device controls the damping characteristic of the exhaust assembly by selectively dividing the gas flow by different amounts between the different gas flow routes. The control device, which may include a valve or a sliceable sleeve, is selectively operable by a user manually or electronically while the combustion engine is operating.

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

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

Abstract: An exhaust gas cooling system for a vehicle includes a cooling fin system retrofit and a side exhaust pipe retrofit having an exhaust gas exit pipe having a first portion having a plurality of mixing portions which are either bends or internal mixing fins configured to mix vehicle exhaust gas, but not to restrict exhaust gas flow, a second portion fastened to the first portion and a chrome coated third portion fastened to the second portion and extending along the side of the vehicle. The cooling fin system retrofit includes an adjustable clamp and one or more cooling fins, each cooling fin having a base having a pair of upstanding arms, with one arm of the pair having a lip for engaging an arm of another cooling fin. An exhaust gas cooling system kit, a side exhaust pipe retrofit kit, a cooling fin kit are included.

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

Abstract: A silencer assembly primarily for the passage therethrough of exhaust gases from an adsorption dryer tower comprises a silencer element to one end of which pressurized gas is directed from an outlet, a control valve downstream of the silencer element, and means for restricting the flow of pressurized gas from the outlet to atmosphere through the silencer element, the arrangement being such that, when the pressure of the gas from the outlet exceeds a predetermined value, the control valve is closed and gas flows from the outlet into and through the silencer element to atmosphere, and, when the pressure of gas from the outlet falls to said predetermined value, the control valve opens and the gas flows from the outlet through the control valve to atmosphere, by-passing the silencer element.

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

Abstract: An automatic compression brake muffler is provided including a muffler pipe. An auxiliary pipe is connected to the muffler pipe and defines passages which are offset from the muffler pipe. Next provided is a mechanical valve having an open orientation for allowing the passage of air through the entire muffler pipe and a closed orientation for precluding the passage of air through the entire muffler pipe and further forcing air through the auxiliary pipe. Finally, a mechanism is included for transferring the mechanical valve to the closed orientation only when a compression brake is actuated.

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

Abstract: This invention relates to an exhaust gas muffler assembly for internal combustion engines which is operable in both a muffled or unmuffled mode. In exterior appearance, the bypass muffler of this invention looks like a conventional muffler having a shell and end caps which enclose the interior components, an inlet for entry of the exhaust gas from the engine, and two outlets for exit of the exhaust gas to atmosphere. A first outlet is preferably positioned opposite to the exhaust gas inlet and connected directly to the inlet by means of a pipe. This pipe is not provided with silencing means. Within the interior of the muffler are silencing means employing a center pipe and an exhaust gas outlet pipe, each of which are provided with silencing means such as apertures in the walls of each pipe. Flow diverting means are removably placed within the first outlet.

Abstract: A muffler having a movable valve disk, with the help of which at least one of the tubes in the muffler housing can be opened and closed. The actuation organ for the valve disk is a corrugated tube, the fixed end of which is placed into an opening in the housing and the interior of which is connected to the atmosphere. As a result, the total pressure loss of the muffler is available as an actuation force.

Abstract: A muffler and an actuating cell provided so that the acoustic properties of the muffler can be changed. The pressure drop in the muffler is fed to the actuating cell as a control pressure. The actuating cell has a plurality of chambers which are separated by diaphragms. Each diaphragm is supported by a spring and each chamber has a pressure connection. A first pressure line feeds the total gas pressure to the overpressure side of the first diaphragm. Another pressure line directs the static gas pressure to the low-pressure side of this diaphragm. Attached to the diaphragm is a piston rod which carries a valve closing element which closes or opens a gas feed pipe.

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

Abstract: A controllable exhaust system of an internal combustion engine is shown which includes an exhaust gas inlet tube extending from the engine, a muffler connected at its inlet side to the exhaust gas inlet tube and having first and second exhaust gas flowing passages defined therein, and first and second exhaust gas outlet tubes respectively connected to the first and second exhaust gas flowing passages and extending from the muffler independently. A muffler controller is incorporated with the exhaust system for varying the flow passage area of the second exhaust gas outlet tube in accordance with the pressure of the exhaust gas led into the muffler from the engine.

Abstract: A first and second noise suppressing mechanism are provided inside the muffler. Each mechanism is provided with a discharge pipe for discharging exhaust gas to outside the muffler. The first noise suppressing mechanism reduces exhaust noise in the low engine speed region. The second noise suppressing mechanism reduces noise in the medium and high engine speed regions. A valve is provided that connects the first noise suppressing mechanism and second noise suppressing mechanism according to the engine exhaust pressure. In the low speed region, the valve is closed and exhaust gas is discharged via the first noise suppressing mechanism where mainly low frequency noise is eliminated. In the medium and high speed regions, the valve is opened and exhaust gas is also discharged via the second noise suppressing mechanism where high frequency noise specific in these regions is also eliminated.