A muffler cutter is fitted to a tailpipe of a vehicular exhaust system, the muffler cutter includes an exhaust pipe, a plurality of through-holes formed in a side wall of the exhaust pipe, a tubular heat shield plate provided around the exhaust pipe coaxially with the exhaust pipe, and a sound-absorbing heat insulator provided between the exhaust pipe and the tubular heat shield plate. The sound-absorbing heat insulator is partially provided between the exhaust pipe and the tubular heat shield plate so as to have a curved shape. A closed space having a curved shape is formed between the exhaust pipe and the tubular heat shield plate in an area in which the sound-absorbing heat insulator is not provided. The distance between the exhaust pipe and the tubular heat shield plate in an area in which the closed space is formed is 1 to 50 mm.

A muffler cutter is fitted to a tailpipe of a vehicular exhaust system, the muffler cutter includes an exhaust pipe, a plurality of through-holes formed in a side wall of the exhaust pipe, a tubular heat shield plate provided around the exhaust pipe coaxially with the exhaust pipe, and a sound-absorbing heat insulator provided between the exhaust pipe and the tubular heat shield plate. The sound-absorbing heat insulator is partially provided between the exhaust pipe and the tubular heat shield plate so as to have a curved shape. A closed space having a curved shape is formed between the exhaust pipe and the tubular heat shield plate in an area in which the sound-absorbing heat insulator is not provided. The distance between the exhaust pipe and the tubular heat shield plate in an area in which the closed space is formed is 1 to 50 mm.

An exhaust gas stream for an internal combustion engine includes a muffler housing (12) with a first chamber (14) and a second chamber (16). An exhaust gas inlet (24) has a first chamber opening area (30) and a second chamber opening area (32). An exhaust gas outlet (36) is open in an outlet opening area (42) towards the first chamber. A connection opening (50) is provided between the first chamber and the second chamber and has an exhaust valve arrangement associated therewith, including a valve element (56) including a closing area (58) closing the connection opening in a closed position of the exhaust valve arrangement (52). The exhaust valve arrangement includes an actuating area (64) associated with the inlet second opening area for generating an actuating force acting on the exhaust valve arrangement, moving from the closed position in the direction of an open position by exhaust gas bypass flow.

An exhaust gas stream for an internal combustion engine includes a muffler housing (12) with a first chamber (14) and a second chamber (16). An exhaust gas inlet (24) has a first chamber opening area (30) and a second chamber opening area (32). An exhaust gas outlet (36) is open in an outlet opening area (42) towards the first chamber. A connection opening (50) is provided between the first chamber and the second chamber and has an exhaust valve arrangement associated therewith, including a valve element (56) including a closing area (58) closing the connection opening in a closed position of the exhaust valve arrangement (52). The exhaust valve arrangement includes an actuating area (64) associated with the inlet second opening area for generating an actuating force acting on the exhaust valve arrangement, moving from the closed position in the direction of an open position by exhaust gas bypass flow.

An exhaust duct assembly for conveying exhaust gases emanating from a combustion zone to atmosphere is disclosed. The assembly includes: an exhaust gas outlet for exhausting exhaust gas into the atmosphere; and an acoustic duct portion located upstream of the exhaust gas outlet, the acoustic duct portion having a peripheral wall defining a through-passage arranged and constructed to promote propagation of sound there-through. The acoustic duct portion has a length in a flow direction that is at least 50% of an average hydraulic diameter of the through-passage.

Systems and methods are provided for a combined spark arrestor and muffler assembly. In one example, a system may include a combined housing, the combined housing including a spark arrestor portion including a plurality of stator fins, and a muffler portion including acoustic packing, the muffler portion fluidically coupled to the spark arrestor portion via a first sliding joint and a second sliding joint. In this way, a single component of a vehicle exhaust system may reduce sparks and/or carbon deposits in exhaust gas, while also reducing exhaust noise.

Systems and methods are provided for a combined spark arrestor and muffler assembly. In one example, a system may include a combined housing, the combined housing including a spark arrestor portion including a plurality of stator fins, and a muffler portion including acoustic packing, the muffler portion fluidically coupled to the spark arrestor portion via a first sliding joint and a second sliding joint. In this way, a single component of a vehicle exhaust system may reduce sparks and/or carbon deposits in exhaust gas, while also reducing exhaust noise.

An engine muffler apparatus for reducing noise and pollution from small gas engines such as those on landscaping tools includes an outer housing having a central neck extension with a principal aperture extending through to an outer housing cavity. The neck extension is selectively engageable with an exhaust of a small gas engine. The outer housing cavity has a plurality of vent apertures. An intake extension tube and a medial tube are coupled to the outer housing cavity. The medial tube has a medial cavity. A first filtering medium is coupled within the medial cavity and filters pollutants passing therethrough. A second filtering medium is coupled within the outer housing cavity outside of the medial tube and dampens sound waves passing through the apparatus from the exhaust.

An engine muffler apparatus for reducing noise and pollution from small gas engines such as those on landscaping tools includes an outer housing having a central neck extension with a principal aperture extending through to an outer housing cavity. The neck extension is selectively engageable with an exhaust of a small gas engine. The outer housing cavity has a plurality of vent apertures. An intake extension tube and a medial tube are coupled to the outer housing cavity. The medial tube has a medial cavity. A first filtering medium is coupled within the medial cavity and filters pollutants passing therethrough. A second filtering medium is coupled within the outer housing cavity outside of the medial tube and dampens sound waves passing through the apparatus from the exhaust.

A substantially metal-free exhaust subsystem includes an exterior housing formed of polymer; and a pipe formed of a layered fibers formed at least partially of glass, and bound by an inorganic binder. The fibers may be glass or ceramic, and may define micro-pores on the interior of the pipe that aid in absorbing acoustic energy, and thereby attenuating exhaust noise.