An air exhausting device includes an inlet pipe that couples an exhaust pipe of an engine to a muffler, an outlet pipe that is a path to discharge an exhaust gas inside the muffler to outside air, and the muffler divided into a plurality of chambers by separators. The muffler is configured of a first expansion chamber, a second expansion chamber with which the outlet pipe is communicated, and a third expansion chamber. The inlet pipe is communicated with the first expansion chamber. The outlet pipe is communicated with the second expansion chamber. The first expansion chamber is adjacent to and communicated with the second expansion chamber via a first pipe. The second expansion chamber is communicated with the third expansion chamber via a second pipe. The first expansion chamber is communicated with the third expansion chamber via a third pipe.

A combined exhaust gas noise silencer consisting of a system of hollow elements with a mutual housing comprising a front face of the silencer connected to the supply pipe of exhaust gases, and a rear face of the silencer with an outlet from the rear face of the silencer, where the originalinlet exhaust gas (?.sub.p) carrying a noise wave is divided into at least two flowsan exhaust gas flow (?.sub.z) carrying a shifted noise wave with delayed wave length, and an exhaust gas flow (?.sub.n) carrying a non-shifted noise wave, which are subsequently combined into a common exhaust gas flow (?.sub.s).

Disclosed is an exhaust-gas after-treatment device for an internal combustion engine, in particular for a ship's diesel internal combustion engine that is operated with heavy oil, including: a housing through which exhaust gas flows; exhaust-gas purification chambers formed in the housing, which chambers hold catalysts and/or particulate filters in order to purify the exhaust gas; and muffler chambers formed in the housing, which chambers have a defined depth for muffling sound in the flow direction. The exhaust-gas purification chambers and the muffler chambers are arranged spatially in series and parallel to one another on the flow side.

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.

A muffler (1) for an exhaust system of a motor vehicle internal combustion engine has a housing (2), with an exhaust gas inlet (4) and an exhaust gas outlet (5), including a circumferentially extending jacket (16) and end panels (14, 15) each axial ends. A chamber (18) in the housing interior (3), through which exhaust gas flows during operation, is axially limited by intermediate panels (20, 21) at axial ends. The thermal load on the jacket (16) is reduced with an insulating shell (29), arranged in the housing interior, extending in the circumferential direction (17) along the jacket (16). The two intermediate panels (20, 21) are supported on the insulating shell (29), each with an outer panel edge (30, 31). The insulating shell (29) is supported radially on the jacket (16) with a shell edge (33). An insulating gap (35) is formed radially between the jacket and the insulating shell.