An acoustic attenuator for damping pressure vibrations in an exhaust system of an engine, the acoustic attenuator having a body which is provided with a gas inlet and a gas outlet at opposite ends thereof, and a gas passage duct arranged between the inlet and the outlet inside the body, where in the body encloses a first resonator chamber and a second resonator chamber. The body is provided with a common inlet communicating with the first and the second resonator chambers, and the resonator chambers are arranged to extend from the common inlet towards the opposite ends of the body.

Provided is a muffler that can reduce sound pressure of a standing wave in an outlet pipe and, at the same time, can inhibit generation of flow noise. In one aspect of the present disclosure, the muffler includes a housing, an outlet pipe, a cover that covers the outlet pipe. The outlet pipe includes an outlet end and at least one communication hole. The outlet end opens into the housing. The at least one communication hole is formed in an outer circumferential surface of the outlet pipe. The cover includes a wall portion and an opening. The wall portion is disposed to overlap with the at least one communication hole in a radial direction of the outlet pipe. The opening communicates the at least one communication hole and an internal space of the housing with each other.

A muffler has a housing enclosing a plurality of chambers. A first flow path extends from an inlet to an outlet passing through a bypass chamber. A flow tube has a plurality of perforations being open to a chamber other than the bypass chamber. A second in flow path passes from the inlet to the outlet without passing through the bypass chamber and passing through the perforations. Exhaust gas is introduced into the muffler via the inlet and discharged therefrom via the outlet. A first portion of the exhaust gas flows from the inlet to the outlet along the first flow path. A second portion of the exhaust gas flows from the inlet to the outlet along the second flow path, the first and second portions mixing at least in the outlet chamber. A semi-closed tube has an open end being open to one of the chambers and a closed end.

An exhaust assembly includes first and second exhaust devices, and first, second, and third mufflers that are disposed at first, second, third, fourth, and fifth heights, respectively. The first and second heights are greater than the third, fourth, and fifth heights. The first muffler includes a first housing, first and second inlets, and first and second outlets. The first inlet receives exhaust gas from at least one of the first and second exhaust devices. The second inlet receives exhaust gas from at least one of the first and second exhaust devices. The first and second inlets and first and second outlets all fluidly connected. The second muffler includes a second housing, a third inlet that receives exhaust gas from the first outlet, and a third outlet. The third muffler includes a third housing, a fourth inlet that receives exhaust gas from the second outlet, and a fourth outlet.

A Helmholtz muffler for a vehicle may include a muffler housing having an internal space divided into a plurality of expansion chamber; a resonance chamber formed hermetically in a vehicle body member; and a connection tube configured to be connected to one of the expansion chambers of the muffler housing and to the resonance chamber.

A muffler for an exhaust system of an internal combustion engine includes a housing, a through pipe that conducts exhaust gas during operation of the muffler and is guided through the housing, and a branch pipe fluidically branching off from the through pipe within the housing. The branch pipe has an upstream end at the through pipe and ends freely and open at an end face with a downstream end within the housing. The branch pipe has a length from the upstream to the downstream end or up to a lateral recess which has a cross-sectional area which is greater than half a pipe cross-section of the branch pipe. The branch pipe has downstream perforations in a section from of the length as measured from the upstream end A total area of the downstream perforations is smaller than half the pipe cross-section of the branch pipe, and no perforations or upstream perforations have a total area of at most 10% of the pipe cross-section of the branch pipe being present in a section before of the length.

An exhaust assembly includes first and second exhaust devices, and first, second, and third mufflers that are disposed at first, second, third, fourth, and fifth heights, respectively. The first and second heights are greater than the third, fourth, and fifth heights. The first muffler includes a first housing, first and second inlets, and first and second outlets. The first inlet receives exhaust gas from at least one of the first and second exhaust devices. The second inlet receives exhaust gas from at least one of the first and second exhaust devices. The first and second inlets and first and second outlets all fluidly connected. The second muffler includes a second housing, a third inlet that receives exhaust gas from the first outlet, and a third outlet. The third muffler includes a third housing, a fourth inlet that receives exhaust gas from the second outlet, and a fourth outlet.

One aspect of the present disclosure provides an exhaust unit including a housing, a wall member, a catalyst, and a muffler chamber. The housing includes a feed inlet and a discharge outlet. The housing is configured such that an exhaust gas of an internal combustion engine is introduced from the feed inlet, and the exhaust gas is discharged from the discharge outlet. The wall member is disposed in the housing, and forms a cylindrical flow path that guides a flow of the exhaust gas introduced from the feed inlet to curve along an outer circumference of an interior of the housing. The catalyst is disposed in the flow path. The muffler chamber communicates with the flow path in a downstream side of the catalyst in the flow path. The wall member serves as a part of a wall that defines an inside and an outside of the muffler chamber.

Provided acoustic devices include an external housing defining an expansion chamber and a wall extending through and partitioning the expansion chamber into a central chamber and a peripheral chamber adjacent the central chamber, wherein an inlet and outlet communicate with the central chamber, and wherein the wall includes a plurality of apertures formed therethrough to allow air movement to and from the central and expansion chambers, the plurality of apertures sized to provide an average flow resistance ranging from 100 MKS Rayls to 5000 MKS Rayls. The acoustic devices advantageously show significant sound attenuation while streamlining air flow to reduce pressure drop across the expansion chamber.

A muffler for receiving exhaust gas from a combustion engine may include a shell, an inlet pipe, at least one outlet pipe, one or more baffles, and an internal communication pipe. The inlet pipe may extend through the shell. The outlet pipe may be in fluid communication with the inlet pipe and may be at least partially disposed within the shell. The baffles are disposed within the shell and cooperate with the shell to define a plurality of chambers. The internal communication pipe may be disposed entirely within the shell and may be in fluid communication with the inlet pipe. The internal communication pipe may include an inlet opening and first and outlet openings. The first outlet opening is open to and in direct fluid communication with one of the chambers. The second outlet opening is open to and in direct fluid communication with another one of the chambers.