A noise abatement system for internal combustion engines comprising: a containment body (12) equipped with an inlet hole (6) for the entry of exhaust gases from an internal combustion engine, a plurality of expansion chambers (10) placed in sequence and separated by parallel dividing partitions (13), each equipped with a through-hole (4) for the passage of gases placing in fluid communication two neighboring expansion chambers (10); said expansion chambers (10) having two opposing through-holes (4), one as gas inlet and one as gas outlet. A rotating shaft (9) is integrated in a rotating turbine (1), along an axis comprising the center of gravity of the expansion chambers (10) up to an opposite end of the containment body (12), said rotating shaft (9) having placed around said axis and on said shaft (9) rotary fins (3) which open and close the through-holes (4) between expansion chambers (10) alternately and generating a swirling movement of the flow of gas entering each expansion chamber (10).

A compact muffler (40) for an engine exhaust system, which is particularly applicable for use with small, reciprocating piston two-stroke engines of the type used on unmanned aerial vehicles (UAVs). The compact muffler (40) comprises an exhaust gas flow path (67) between an inlet (61) and an outlet (63). The exhaust gas flow path (67) comprises a plurality of adjacent flow passages (65), wherein at least two of the adjacent flow passages (65) are fluidly connected in series to enable the flow of exhaust gas from one to the other along the flow path (67). The adjacent flow passages (65) are configured for fluid flow therealong in opposed directions. A bypass passage (70) is provided between the two adjacent flow passages (65) for further communication between the two flow passages and to promote an equalisation of fluid pressure within the two adjacent passages (65). A UAV having an internal combustion engine (31) fitted with an exhaust system comprising the compact muffler (40) is also disclosed.

Method for forming a collar in a muffler shell including: providing a muffler shell made of a metal sheet and forming a muffler housing, the muffler shell having an exhaust gas opening, providing a collar forming head having a rotational axis and at least two movable expanders, introducing a collar forming head into a muffler housing, moving the expanders of the collar forming head introduced into the muffler shell radially away from the rotational axis of the collar forming head from a retracted position to an expanded position rotating the collar forming head around the of the collar forming head, bringing the rotating expanded collar forming head in contact with the metal sheet forming an outwardly projecting collar around the exhaust gas opening by flaring the edge of the metal sheet.

An internal combustion engine includes an engine block including a cylinder and a muffler assembly configured to receive exhaust gases from the cylinder. The muffler assembly includes a housing defining an interior volume and including an exhaust inlet and an exhaust outlet, and a baffle assembly positioned within the interior volume. The baffle assembly includes a plurality of chambers in fluid communication with each other. The plurality of chambers are in fluid communication with the exhaust inlet and the exhaust outlet so that the plurality of chambers are configured to cause exhaust gases to be directed through the muffler assembly from the exhaust inlet to the exhaust outlet through four passes in the baffle assembly before exiting through the exhaust outlet.

A muffler for an exhaust system of an internal combustion engine includes a muffler housing (14) and at least one exhaust gas pipe group (19). The at least one exhaust gas pipe group (19) includes an outlet pipe (20) open towards an expansion chamber (26) formed in the muffler housing (14). Exhaust gas introduced via the at least one exhaust gas pipe group (19) leaves the muffler housing (16) via the outlet pipe (20). A first inlet pipe (38), of the at least one exhaust gas pipe group (19), has an inlet pipe end area (40), which is inserted into the outlet pipe (20) and extends in the outlet pipe (20). A second inlet pipe (48), of the at least one exhaust gas pipe group (19), is open towards the expansion chamber (26).

The dual function exhaust system attachment, which is preferably used with an all-terrain vehicle, includes a muffler, a silencing cap, and a sound-enhancing plug. In a quiet configuration, the silencing cap is mounted to conceal a primary outlet of the muffler. In a loud configuration, the sound-enhancing plug is mounted to conceal a secondary outlet of the muffler. A set of screw threads or sealing mechanism may be used to mount the silencing cap and the sound-enhancing plug. A primary perforated barrier, a solid barrier, at least one secondary perforated barrier, and a pipe section are positioned within a hollow structural body of the muffler to guide the exhaust gas flow from an inlet of the muffler to the primary outlet or the secondary outlet.

The vehicle of the present application includes a vehicle frame; a muffler supported by the vehicle frame; and a supporting unit comprising a rubber damper, located between the muffler and the vehicle frame and, connected to the vehicle frame such that the muffler is suspended from the vehicle frame and supported by the vehicle frame. The supporting unit comprises a first bracket and a second bracket on the first bracket.

An exhaust gas purification device includes a pre-oxidation catalyst disposed in an exhaust gas passage and a muffler that is provided in such a manner as to surround the pre-oxidation catalyst, and discharges exhaust gas while reducing noise. The muffler has an inlet which is connected to an upstream side exhaust pipe and an outlet which is connected to a downstream side exhaust pipe. The exhaust gas purification device includes a downstream side purification device that is disposed in the exhaust gas passage, and accommodates a second oxidation catalyst and a particulate matter removing filter. The exhaust gas is discharged to the atmosphere after the exhaust gas flows through the downstream side purification device.

A silencing apparatus is provided with a shell, ventilation pipes communicating with the inside of the shell, insertion holes which are respectively formed in the shell so as to have sizes smaller than surrounding skirt parts and allow the ventilation pipes to be loosely inserted in, and partitions partitioning the inside of the shell. In the silencing apparatus, at least, a sound-absorbing chamber partitioned by the partition and positioned adjacent to the insertion hole is filled with a sound-absorbing fiber material, and a sound-absorbing fiber material filling gap between the insertion hole and the ventilation pipe is closed by an annular closing member. To provide a silencing apparatus allowing a sound-absorbing chamber to be filled with sound-absorbing fiber material without a gap, even in a complicated configuration having the inside of a shell partitioned by a partition.

Shockwave suppression is accomplished by channeling a shockwave from a shockwave source, such as a firearm, into a suppression device along a propagation path, and within the suppression device, deflecting a portion of the shockwave away from the firing axis, and channeling the deflected portion through a feedback path and back to a region behind the deflected shockwave. The suppression device can be formed from one more chambers arranged within an outer wall and including baffles and inner wall sections.