A muffler including a double-pipe structure to muffle sounds in two or more frequencies is provided. The muffler includes an inner and outer pipes with a clearance therebetween. The inner pipe includes a first and second outer surfaces, and, at one end, an opening communicating with the outer pipe. The clearance communicates with an exhaust passage via the opening. The second outer surface forms the opening and is situated closer to the center of the inner pipe than the first outer surface is. A space between the inner and outer pipes is closed due to a contact between the first outer surface and an inner-circumferential surface of the outer pipe. A part of the clearance is formed between the first outer surface and the inner-circumferential surface. The outer-circumferential surfaces of the inner pipe include at least one communication hole that communicates the inner pipe with the clearance.

An exhaust-gas aftertreatment device (10) for an internal combustion engine, particularly for a marine diesel internal combustion engine operated using heavy fuel oil, includes a housing (11); an exhaust-gas chamber (12) defined by the housing (11), for permitting exhaust gas to flow continuously through the housing (11), an inlet (13) for permitting exhaust gas to flow into the housing and an outlet (14) for permitting exhaust gas to flow out of the housing (11); a sound damping chamber (15), defined by the housing (11) and coupled with the exhaust-gas chamber (12). The sound dampening chamber (15) is constructed to receive a fluid or a pourable solid at a fill level depending on the frequency of an exhaust sound to be damped.

An exhaust structure for a straddle-type vehicle includes a muffler having an outer tube constituting an outer circumferential member of the muffler; first and second separators defining expansion chambers in the outer tube; a body end member arranged at the downstream end of the outer tube; and glass wool provided on the inner circumference of the outer tube. The muffler further includes a resonator chamber provided in the most downstream portion of the muffler. The resonator chamber is formed by the outer tube, the body end member and the second separator situated closest to the body end member. The surroundings of the resonator chamber are surrounded by the glass wool. Such exhaust structure of a straddle-type vehicle is capable of taking measures against exhaust heat and exhaust sound even with a configuration where there is only one, single resonator chamber.

A muffler for a vehicle, where the muffler comprises a partition wall that divides the interior in a first chamber and a second chamber, where an inlet pipe comprising a perforated section arranged in the first chamber and a closed section arranged in the first chamber, where the outlet opening of the inlet pipe is arranged in the second chamber, a first outlet pipe comprising an inlet opening arranged in the first chamber and an outlet opening arranged outside of the muffler, where the muffler comprises a second outlet pipe having an inlet opening arranged in the second chamber, and where the second outlet pipe is provided with an exhaust valve adapted to open or close the exhaust gas flow through the second outlet pipe. The advantage of the invention is that a muffler with an improved low frequency noise attenuation and low backpressure is provided.

A heat exchange and noise reduction panel the panel for an aircraft comprising: an external surface intended to be swept by an airflow and from which fins extend along a first and a second main predetermined direction; cavities forming Helmholtz resonators, linked to the first ends of channels for the passage of air, the second ends of which communicate with said airflow, such that said channels form necks, referred to as Helmholtz resonators, extending substantially along the first direction; and at least one oil flow chamber extending between said external surface and said at least one cavity, and intended to discharge the thermal energy carried by the oil, characterized in that wherein said channels are formed, at least in part, inside said fins.

A vehicle exhaust system component includes an exhaust tube defining an exhaust gas flow path, a side branch tuning tube connected to the exhaust tube at an interface, and a porous structure associated with the exhaust tube to reduce noise generated at the interface. In one example, the porous structure comprises a perforated orifice in the exhaust tube. In another example, the porous structure comprises a mesh screen or mesh sleeve.

An internal combustion (IC) power plant includes an IC engine and an exhaust system carrying exhaust gasses from the IC engine to an outlet communicating to the atmosphere.

A sound generator (1) includes a casing (10) with at least one exhaust gas inlet (11) and at least one exhaust gas outlet (12) that is different from the at least one exhaust gas inlet (11) and at least one electro-acoustical transducer (20). The electro-acoustical transducer (20) is configured to produce sound in dependence on an electrical control signal. The electro-acoustical transducer (20) is located within the casing or directly attached to the casing. An active noise control system (9) includes the sound generator (1). A vehicle (8) with an internal combustion engine (6) includes the active noise control system (9).

A muffler includes a first chamber, a second chamber, an extender tube, a reverse flow tube, and a separation chamber. The first chamber is coupled to an exhaust inlet of the muffler. The extender tube is coupled to the first chamber and the second chamber. The exhaust gas flows from the first chamber to the second chamber through the extender tube in a first direction. The reverse flow tube coupled to the second chamber. The exhaust gas flows through the second chamber from the extender tube to the reverse flow tube in a second direction different than the first direction. The separation chamber that provides spatial separation between the first and second chamber.

A muffler for a vehicle includes: a case sealed at both ends by first and second side panels; first and second baffle plates installed in the case; a first chamber formed between the first side panel and the first baffle plate; a second chamber formed between the first baffle plate and the second baffle plate; a third chamber formed between the second baffle plate and the second side panel; an intake tube passing through the first side panel, and the first and second baffle plates, and including a first hole formed in a first body section located in the first chamber, and a second hole formed in a second body section located in the second chamber; and a pair of exhaust tubes passing through the first and second baffle plates, and the second side panel, and including a vent hole formed in body section located in the second chamber.