Abstract: Disclosed are exhaust systems for two-stroke engines mounted on bicycles. The exhaust systems include an expansion chamber having a divergent portion and convergent portion. The expansion chambers have different dimensions for the divergent portion and the convergent portion. The exhaust systems improve the power performance of the two-stroke engines operating at below maximal RPM by between about 15% and about 85% when compared to that of the two-stroke engines equipped with a stock exhaust pipe.

Abstract: A poppet-type EGR valve includes: a housing that includes a flow passage; a valve seat; a valve body allowed to be seated on the valve seat; a valve shaft on which the valve body is provided at one end section thereof; and a drive unit reciprocally driving the valve shaft. The flow passage has an inlet and an outlet and includes a bent passage portion that is bent downstream from the valve seat in a direction perpendicular to the direction toward the inlet. The bent passage portion includes at least one of a section in which the passage area is constant and a section in which the passage area increases toward the downstream direction, and does not include a section in which the passage area decreases toward the downstream direction. In the section in which the passage area increases toward the downstream direction, the passage area changes gradually.

Abstract: A muffler assembly for an exhaust system is in fluid communication with a collector via an exhaust conduit. The muffler assembly includes a primary pipe, a valve, a secondary pipe, a tuner tube and a bleed port. The primary pipe extends through an enclosed volume of the muffler. The valve is operable to restrict flow through the primary pipe. When a standing wave is present, a resonance length is defined by a length of the exhaust system that extends from the collector to the valve. The tuner tube includes an open tuner tube end in fluid communication with the primary pipe and a closed tuner tube end. The tuner tube has a tuner tube length that is substantially one-quarter of the resonance length. The bleed port is formed in the primary pipe, allowing fluid communication with the enclosed volume, and positioned downstream from open tuner tube end.

Abstract: An exhaust passage structure of an internal combustion includes a first merging passage, a second merging passage, and a third merging passage connecting a third gathering portion in which the exhaust gas flowing through the first merging passage and the exhaust gas flowing through the second merging passage gather and a turbine of a turbocharger. The first merging passage and the second merging passage have respective narrowed portions in which passage cross-sectional areas are minimized. When a total value of passage cross-sectional areas of inlets of exhaust ports in one cylinder is set as a reference passage cross-sectional area A, and the passage cross-sectional areas of the narrowed portions of the first merging passage and the second merging passage are set as narrowed cross-sectional areas B, the exhaust passage structure is configured such that the relationship of 0.5?(B/A)?1 is established.

Abstract: The disclosure presents methods and apparatus that can be used to generate a software source code according to a user-provided specification based on example snippets searched from the Internet or a local database, comprising: providing a user-defined specification of the target program including input data, output data, a function or algorithm, and other parameters; decomposing the function into sub-functions if necessary; searching a list of related programming example codes and snippets of each sub-function; analyzing and ranking the search results; selecting and extracting the best snippet source codes; refactoring and reformatting the codes; gluing and testing the generated codes. The final source codes are supposed to be compiled successfully and implement the desired function and meet the performance requirements. Even the final compilation success is not guaranteed the described method and apparatus can help on a best-effort basis and reduce a great effort in programming.

Abstract: Electric chain saw with static cooling features a cutting chain fitted so as to turn around a drive sprocket and a guide bar of oblong shape, and an electric motor effecting the drive of this chain, through the intermediary of the sprocket. The electric drive motor drive of the cutting chain is a brushless direct current motor enclosed in a housing formed by at least two components and made of a light metallic alloy, with one surface of the housing being in contact with the drive motor drive, to provide static cooling.

Abstract: A shunt pulsation trap for a positive displacement (PD) internal combustion engine (ICE) reduces pulsation, as well as noise, vibration and harshness (NVH), and the overall size of the exhaust system, and also improves cycle (fuel) efficiency. A shunt pulsation trap for a PD-ICE is configured to trap and attenuate gas pulsations before discharge to engine outlet and includes a chamber (trap volume) adjacent to the PD-ICE cavity. The chamber houses at least one pulsation dampening device, at least one relief port (trap inlet) branching off from the PD-ICE cavity into the pulsation trap chamber and a feedback region (trap outlet) communicating with the PD-ICE outlet. The associated methods of reducing pulsations are included as another aspect of the invention.

Abstract: An engine-driven work machine including: a two-cycle engine including a piston which is configured to reciprocally move inside a cylinder to which an exhaust port is formed; and a front end tool configured to be driven by the engine, wherein an expansion chamber is connected to the exhaust port via a connection duct, wherein the connection duct includes a first end and a second end, and the connection duct extends from the first end in an axial direction of the exhaust port, is bent in a direction away from an axis of the exhaust port and is connected to the expansion chamber at the second end, and wherein a housing of the expansion chamber is disposed at an inner side of the connection duct and an engine block including the cylinder and a crank case.

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: An exhaust pipe for two-stroke, internal-combustion engines in which there are multiple exhaust expansion chambers, each within one another, used in combination, the multiple chambers allow for the combustible fuel/air mixture to be delivered in more optimal reflective pressure waves throughout the RPM range of the engine. By changing the number of the chambers, their size and shape, the design of the exhaust pipe can be tuned for torque and power while requiring a minimum of space.

Abstract: An exhaust system for an internal combustion engine, having a first exhaust tract assigned to a first group of cylinders of the internal combustion engine, and having a second exhaust tract assigned to a second group of cylinders of the internal combustion engine, each exhaust tract comprising an exhaust gas purification device, a first silencer arranged on the outlet side of the respective exhaust gas purification device, and a second silencer arranged on the outlet side of the respective first silencer. Each exhaust tract includes a bypass line, it being possible for exhaust gas to be diverted via each bypass line, starting from the respective first silencer, bypassing the second silencers, and the bypass lines and hence the first silencers of both exhaust tracts being connected to one another by a mixing line.

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

Abstract: A modular tuned exhaust pipe coupled to a remote controlled vehicle having a two stroke motor, having a body portion with an exhaust port. A convergent cone section is internally and slidingly mounted within the body portion and has an at last one exhaust hole. An adjustment Mechanism coupled to the convergent cone section. The turning of the adjustment mechanism slidingly moving the convergent cone within the body portion to adjust the tuned length of the modular tuned exhaust pipe. And a pressure adjustment screw, the pressure adjustment screw penetrating the body portion such that turning of the pressure adjustment screw increases or decreases the pressure within the modular tuned pipe.

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

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

Abstract: In an internal combustion engine having several combustion chambers formed in in-line cylinders wherein an air/fuel mixture can be combusted and which include a common cylinder head, with discharge passages formed within the cylinder head and extending to a common confluence zone in communication with a discharge manifold, the common confluence zone is delimited on a first side (A) by at least one cylinder head wall and a separate shell element on a second side mounted to the outside of the cylinder head, the shell element being curved funnel-like for conducting the exhaust gas away from the engine.

Abstract: An exhaust throttle valve protected from disturbance due to stones scattered during operation of a vehicle. Front side exhaust pipes and rear side exhaust pipes are connected to a catalyst chamber disposed below a crankcase. The catalyst chamber and an exhaust chamber disposed to the rear thereof are connected to each other via a rear exhaust pipe. The diameter of the rear exhaust pipe is smaller than the lateral width of each of the catalyst chamber and the exhaust chamber, so that a recessed space is externally formed so as to recede inside of the vehicle. An exhaust throttle valve is received in the space. The exhaust throttle valve is partially exposed to the outside of the rear exhaust pipe and a throttle valve is received in the rear exhaust pipe to throttle-control the passage-sectional area of the rear exhaust pipe according to the rotation of the engine.

Abstract: A silencer for a motorcycle with relaxed layout restrictions has a drum portion connected to a head. A conduit extends through the drum portion in a direction of connection. The drum portion decreases in cross sectional area toward a downstream side. A catalyst holding portion formed in the head has a catalyst fixed member to which a catalyst inserted member is fixed at a position upstream of the drum portion. A catalyst is inserted into the catalyst inserted member.

Abstract: An exhaust system for a two-cycle engine includes an exhaust conduit having both a bypass port and a regulator port for discharging exhaust gases to atmosphere. The bypass port has a fixed size but the regulator port has a variable size that varies over the range of engine speeds. Within a low range of operating speeds, the regulator valve is at least partly closed. Within a mid range of operating speeds, the regulator valve is progressively opened with increases in the operating speed. Within a high range of operating speeds, the regulator valve is progressively closed with further increases in the operating speed.

Abstract: An exhaust system for a motorcycle engine including a header having an upstream end adjacent a combustion chamber of the engine and having a downstream end opposite the upstream end. The exhaust system includes a catalytic converter positioned downstream of the combustion chamber and configured to improve the emissions quality of exhaust gases discharged from the combustion chamber. The exhaust system further includes a perforated section at least partially defining an exhaust passageway, the perforated section disposed adjacent the downstream end of the header. A resonator chamber is in fluid communication with the perforated section. The resonator chamber is configured to allow expansion of the exhaust gases in the exhaust passageway through the perforated section.

Abstract: The engine exhaust system may allow scavenging of two-stroke engines using a retro-tube attached to an exhaust port of a two-stroke engine. Intake air may be obtained directly from environmental air at atmospheric pressure allowed by engine cycle operation and an approximately constant diameter retro-tube having a volume approximately equal to a swept volume of the piston movement.

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

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

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: An arrangement for controlling exhaust pressure pulsation in a combustion engine including six cylinders. The engine also includes an inlet for supply of air to the cylinders, and an exhaust manifold for delivery of exhaust gases from the cylinders. The manifold is provided with a first outlet to an exhaust system and with a second outlet to a conduit for feeding exhaust gases back, via an EGR circuit, from at least one of the engine's cylinders to the inlet. At least one of the cylinders is adapted to enrich the exhaust gases with unburnt hydrocarbon with a view to regeneration of an exhaust gas post-treatment unit situated in the exhaust system. A special configuration of the exhaust manifold results in separation of regeneration gas from EGR gas in the exhaust manifold.

Abstract: A modular tuned exhaust pipe coupled to a remote controlled vehicle having a two stroke motor, having a body portion with an exhaust port. A convergent cone section is internally and slidingly mounted within the body portion and has an at last one exhaust hole. An adjustment Mechanism coupled to the convergent cone section. The turning of the adjustment mechanism slidingly moving the convergent cone within the body portion to adjust the tuned length of the modular tuned exhaust pipe. And a pressure adjustment screw, the pressure adjustment screw penetrating the body portion such that turning of the pressure adjustment screw increases or decreases the pressure within the modular tuned pipe.

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: An engine body of the multiple-cylinder engine for an outboard motor can include a crankcase for supporting a crankshaft whose axis extends vertically, and plural cylinders that are vertically arranged in line, each cylinder horizontally extending outward from the crankcase, and each cylinder having a respective exhaust port formed in a cylinder head. There are can be provided plural exhaust passages, each passage extending from the downstream end of the exhaust port, each passage communicating with the exhaust port and expansion chambers. Each expansion chamber can communicate with the extending end of the exhaust passage.

Abstract: A muffler device with catalysts for improving purifying exhaust gas of nitrogen oxides within a motorcycle exhaust pipe comprises a muffler divided into three chambers, a first chamber, a second chamber, and a third chamber; a front exhaust pipe; a front reduction catalyst; a rear exhaust pipe provided with a secondary air inlet behind the reduction catalyst for introducing secondary air therein. Thereby, the exhaust gas from an engine with air-to-fuel ratio less than or equal to 14.7 will firstly pass the reduction catalyst to have its nitrogen oxides (NOX) effectively inverted into nitrogen (N2) and oxygen (O2), and then secondary air will be added to the exhaust gas so as to increase its air-to-fuel ratio to larger than 14.7, and finally the exhaust gas will pass the oxidation catalyst to have its carbon monoxide (CO) and hydrocarbons (HC) effectively inverted into carbon dioxide (CO2) and water (H2O).

Abstract: Sound and power are an important part of the motorcycling experience. From the early days people have been attempting to get it “right” and have tried numerous ways to achieve the best of both worlds. Generally one had to be sacrificed to some degree to get the other. Tuning the exhaust rather than tuning the carburetor or increasing cubic inches is a less expensive and more efficient way to get both the sound and midrange power that motorcyclists are looking for. With the exhaust enhancement device of the present invention, exhaust pipes can be tuned for sound and increased midrange power very simply and easily by installing them in the exit end of an aftermarket straight type pipe using various combinations to achieve a desired sound and not sacrifice power.

Abstract: A two cycle internal combustion engine cylinder having a piston chamber. The cylinder includes transfer ports; and an exhaust port divided into at least two sections. A first one of the sections has an aperture at the piston chamber with a top surface located closer to a top of the piston chamber than a top surface of an aperture of a second one of the sections at the piston chamber. The first section has a cross-sectional area which is smaller than a cross-sectional area of the second section. The aperture into the first section is located further away from the transfer ports than the aperture into the second section.

Abstract: A motorcycle includes an axle of a rear wheel supported for rotation at a rear end of a swing arm. The swing arm is supported at a front end portion thereof for rocking motion on a vehicle body frame. A rear end exhaust portion of an exhaust system connected to a cylinder head provided on an engine body carried on the vehicle body frame forwardly of the rear wheel is disposed at a position higher than the axle. An exhaust control valve for adjusting the flow area in an exhaust pipe, which forms part of the exhaust system, is disposed in the exhaust pipe. The exhaust control valve is disposed forwardly and upwardly of the axle of the rear wheel to dispose the exhaust control valve in a better environment.

Abstract: An exhaust-gas muffler includes a muffler housing (2) having an inlet opening (3) and an outlet (4). The exhaust-gas muffler is especially for the internal combustion engine in a portable handheld work apparatus. At least one attenuating space (5, 5?, 5?) is configured in the exhaust-gas muffler (1). The exhaust-gas muffler (1) includes at least one resonance pipe (6) to increase power and to reduce the hydrocarbon emissions. The resonance pipe (6) is fluidly connected to the inlet opening (3) and the resonance pipe leads to a backflow of exhaust gases into the combustion chamber (22). For a simple manufacture, it is provided that the exhaust-gas muffler (1) includes lower and upper half shells (8, 7) via which the resonance pipe (6) is at least partially delimited.

Abstract: A motorcycle exhaust control system for covering exhaust cross-over pipes is comprised of an elongate tubular crossover block-off member having a side wall. The crossover block-off member side wall has a slit extending the length thereof. The crossover block-off member forms the springed structure capable of placement in a motorcycle exhaust pipe. The crossover block-off member is capable of self-detainment in the motorcycle exhaust pipe. The crossover block-off member is capable of blocking the motorcycle exhaust pipe crossover.

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: A muffler assembly for an internal combustion engine of a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine or the like includes an exhaust-gas muffler (1) which has a muffler housing (10). The muffler housing (10) is formed essentially from two half shells (24, 25) connected substantially fluid-tight to each other. The interior space of the muffler housing (10) includes at least two chambers (2, 3) which are partitioned from each other by a partition wall (4). A catalytic converter (5) is mounted in the partition wall (4). In the interior space of the muffler housing (10), an exhaust-gas inlet (6) opens which is connected to an exhaust-gas stub (9) of the cylinder (8) of the engine. The exhaust-gas muffler has an exhaust-gas outlet (7) which conducts exhaust gas from the interior space.

Abstract: An exhaust muffler system for use on a motorcycle or four-wheeled vehicle provides for operation in either of two modes, a regular configuration that provides a high degree of noise reduction, or a racing specification that provides for a freer-flowing exhaust. Without changing the main body of the muffler, an operator can choose between a quieter, public road setting or a louder, high performance setting. The muffler is provided with two interchangeable spark arresters, and a main body having multiple expansion chambers therein, defined by bulkheads. When a regular spark arrester is installed, exhaust gas passes through one bulkhead three times, greatly reducing the noise produced. With the spark arrester removed, the exhaust gas passes straight through to the open air, enhancing performance. A seal is provided between the bulkheads and the spark arrester, which provides for extension or retraction in the lengthwise direction of the tail pipe.

Abstract: An exhaust processor has an exhaust tube and a cover mounted for rotation at least partially around the exhaust tube to adjust the tuning frequency of the exhaust processor. A method of operating the exhaust processor is also disclosed.

Abstract: Sound and power are an important part of the motorcycling experience. From the early days people have been attempting to get it “right” and have tried numerous ways to achieve the best of both worlds. Generally one had to be sacrificed to some degree to get the other. Tuning the exhaust rather than tuning the carburetor or increasing cubic inches is a less expensive and more efficient way to get both the sound and midrange power that motorcyclists are looking for. With the Exhaust Enhancement exhaust pipes can be tuned for sound and increased midrange power very simply and easily by installing them in the exit end of an aftermarket straight type pipe using various combinations to achieve a desired sound and not sacrifice power.

Abstract: An exhaust system for use with a four-stroke engine having first and second cylinders. The cylinders generate exhaust pulses at uneven time intervals with respect to each other. The exhaust system includes a muffler and first and second exhaust pipes that communicate between the mufflers and the first and second cylinders, respectively. The first and second pipes being sized and shaped to deliver the exhaust pulses to the muffler at even time intervals with respect to each other.

Abstract: The invention is an adjustable exhaust system and an adjustable insert for an exhaust system. The exhaust system includes a header flange, at least one conduit coupled to the header flange, a collector coupled to the conduit, and an adjustable insert for tuning engine performance.

Abstract: An exhaust system for a two-cycle internal combustion engine combusting a normally gaseous hydrocarbon as fuel, the engine having a cylinder having an exhaust port in communication with an exhaust manifold. The exhaust system has an exhaust gas inlet connectable to the exhaust manifold of the internal combustion engine and an exhaust gas outlet spaced from the exhaust gas inlet in the direction of flow of exhaust gas through the system. A first tubular portion is disposed between the exhaust gas inlet and outlet, the first tubular portion diverging in the direction of flow. A second tubular portion is disposed between the exhaust gas inlet and outlet and spaced from the first tubular portion in the direction of flow, the second tubular portion converging in the direction of flow.

Abstract: A number of embodiments of acoustical devices for improving either or both the intake and exhaust sounds emanated from an internal combustion engine. This is achieved by employing acoustical devices which are configured so as to discharge the desired sound waves to the atmosphere rather than by attempting to dampen the undesired sound waves generated in the system.

Abstract: An internal combustion engine, especially of a two-stroke engine in a portable handheld work apparatus, includes an outlet (27) for the exhaust gases which is fluidly connected with at least one inlet opening (13, 14) in an exhaust-gas muffler (1). At least one resonance pipe (6, 7) is mounted in flow direction between the outlet (27) from the engine (20) and the inlet opening (3, 5) into the exhaust-gas muffler (1) in order to obtain a good noise attenuating result and simultaneously make possible an advantageous, space-saving mounting of the engine (20).

Abstract: A two-stroke internal combustion engine (1) is provided with a muffler device (2). In one example, the engine (1) is intended for a working tool, such as a chain saw or a trimmer. A pipe (3), which either is straight or bent, and having an adapted or tuned length and a closed outer end (4), is arranged in connection to the engine's exhaust port (5) as well as an outlet (6), which leads the exhaust gases to the surrounding air. By this arrangement of the pipe (3) and the outlet (6) the scavenging losses are reduced and thereby the specific fuel consumption is reduced and cleaner exhaust gases are achieved.

Abstract: A stratified scavenging two-cycle engine with catalyst capable of meeting such a requirement that a THC exhaust rate is 54 [g/kW·h] or less with use of catalyst. For this purpose, in the stratified scavenging two-cycle engine in which an air feed volume ratio R of an air feed volume (qa) flowing through the air feed passage (24) to a mixture feed volume (Qf) flowing through the mixture feed passage (20) is within a range of 0.7≦R≦1.4 during an intake stroke in which the crank chamber (8) becomes negative pressure, oxidation catalyst (47) is placed midway in an exhaust passage in a downstream of an exhaust hole (14).

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: An exhaust system for an internal combustion engine of an outboard motor is provided. The exhaust system provides dual exhaust passages, simplifying the engine's construction and reducing manufacturing costs, while optimizing engine performance. The exhaust system includes exhaust ports having equal lengths that avoid differential pressure losses across cylinders. The arrangement of the exhaust passages enables a cowling to have a tapered aerodynamic design.

Abstract: An exhaust system for a two-cycle internal combustion engine combusting a normally gaseous hydrocarbon as fuel, the engine comprising a cylinder having an exhaust port in communication with an exhaust manifold. The exhaust system comprises an exhaust gas inlet connectable to the exhaust manifold of the internal combustion engine and an exhaust gas outlet spaced from the exhaust gas inlet in the direction of flow of exhaust gas through the system. A first tubular portion is disposed between the exhaust gas inlet and outlet, the first tubular portion diverging in the direction of flow. A second tubular portion is disposed between the exhaust gas inlet and outlet and spaced from the first tubular portion in the direction of flow, the second tubular portion converging in the direction of flow.