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.

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).

An exhaust muffler includes a first muffler section having a tubular member made up of an inner pipe to which an exhaust pipe is connected and an outer pipe covering the inner pipe, and a connector connecting the tubular member and a second muffler section to each other, and the second muffler section having an outer shell, a first partition wall, a second partition wall, and a third partition wall. Exhaust gases delivered from the exhaust pipe are discharged from the first muffler section and the second muffler section out of the exhaust muffler. The second muffler section has a cross-sectional area larger than a cross-sectional area of the tubular member. The exhaust muffler includes a first expansion chamber, a second expansion chamber, and a third expansion chamber. The second muffler section includes a fluid communication pipe extending through the first partition wall and the second partition wall for leading exhaust gases from the first expansion chamber into the second expansion chamber, and an exhaust passage pipe held in fluid communication with the third expansion chamber and extending through the second partition and the third partition wall. The second partition wall has a fluid communication hole defined therein that provides fluid communication between the second expansion chamber and the third expansion chamber. There is thus provided an engine exhaust device capable of increasing a silencing capability by increasing the length of a route through which the exhaust gases flow while maintaining the length of the exhaust device.

There is provided an exhaust device that purifies exhaust gas discharged from an engine through an exhaust pipe. The exhaust device includes: a chamber that forms an expansion chamber of the exhaust gas at a downstream side of the exhaust pipe; a partition wall that partitions the expansion chamber into a first expansion chamber and a second expansion chamber; an introduction pipe that enters the second expansion chamber from a downstream end of the exhaust pipe; and a catalyst interposed at an intermediate portion of the introduction pipe in the second expansion chamber. The partition wall is formed with a first opening connecting an outlet of the introduction pipe to the first expansion chamber and a second opening connecting the first expansion chamber to the second expansion chamber, and the second opening overlaps with the catalyst when viewed from a side of the first expansion chamber.

An insert assembly unit for a muffler of an exhaust system of an internal combustion engine includes two walls (12, 14) arranged at spaced locations from one another. Each of the two walls has a circumferential edge area (20, 22) configured for fixing at a circumferential wall of a muffler. An exhaust gas flow unit (26) is arranged between the two walls. The exhaust gas flow unit includes a flow duct area (34) with an exhaust gas outer flow opening (38) to be positioned directed towards an opening in a circumferential wall of a muffler, a first mounting duct area (40) with a first mounting opening (44) for fixing the exhaust gas flow unit at a first wall of the walls, and a second mounting duct area (42) with a second mounting opening (46) for fixing the exhaust gas flow unit at a second wall of the walls.

A muffler for an exhaust system of an internal combustion engine includes at least one muffler component with a perforation defined by a plurality of through-flow openings in a wall of the muffler component. The through-flow openings can be flowed through in a flow direction in the direction from an upstream side of the wall to a downstream side of the wall. At least in the case of some or all of the through-flow openings of the perforation, a through-flow opening flow cross section decreases in the flow direction in order to provide a through-flow opening flow-guiding surface.

A muffler for an engine includes a muffler body, at least one partition wall, and at least one reinforcing plate. The muffler body has an inner space formed by a shell. The partition wall includes a flange portion which is in tight contact with an inner surface of the shell, and the partition wall divides the inner space of the muffler body into a plurality of chambers. The reinforcing plate is welded on an outer surface of the shell at a position facing the flange portion of the partition wall.

An exhaust muffler for an exhaust system of an internal combustion engine includes a muffler housing (12) with an outer shell (14) enclosing a muffler interior (22), through which exhaust gas can flow. An inner shell (54) is arranged in the muffler interior (22) and covers the outer shell (14) in at least some areas on an inner side (52) facing the muffler interior (22).

An aftertreatment component includes an inlet connector tube, an outlet connector tube, a chamber, a flow dissipater, and a substrate. The inlet connector tube receives exhaust gasses. The chamber is between the inlet connector tube and the outlet connector tube. The flow dissipater is positioned around the inlet connector tube and within the chamber. The flow dissipater receives the exhaust gasses from the inlet connector tube and includes a plurality of perforations. The plurality of perforations defines an open area of the flow dissipater. The open area of the flow dissipater is greatest proximate to the inlet connector tube and progressively decreasing proximate to the outlet connector tube. The substrate is positioned within the chamber and receives the exhaust gasses from the flow dissipater and provides the treated exhaust gasses to the outlet connector tube. The exhaust gases are expelled through the flow dissipater via the plurality of perforations.