A muffler having a movable baffle may include a housing where an input pipe into which exhaust gas is flowed from an engine and an output pipe through which the exhaust gas is expelled to atmosphere are disposed, a baffle which is configured to be slidable along the longitudinal direction of the housing and divides the space of the housing, baffle moving means for moving the baffle to an arbitrary position within a predetermined range along the longitudinal direction of the housing, and a controller which data for determining whether to move the baffle or not is input thereto when the engine is driven, determines whether to move the baffle or not by use of the input data and controls the baffle moving means when the baffle is determined to be moved.

An exhaust plume control structure includes a mounting member configured to mount to an exhaust flow source. A diverter member is coupled to the mounting member to radially direct an initial exhaust flow exiting from the exhaust flow source radially outward. A plurality of peripherally spaced, radially extending vanes are coupled to the mounting member and radially outward of the diverter member to separate the radially outward directed initial exhaust flow into a plurality of additional exhaust flows. Each vane has a radially diverging cross-section. Each of the plurality of additional exhaust flows has a same radial exit velocity. The structure reduces exhaust flow velocity and may provide back pressure to the initial exhaust flow. The structure has a sound power level of less than 115 dBA. A power generating plant including the structure is also disclosed.

A muffler, connected to an engine through an exhaust pipe, includes a shell serving as a muffler body, an inlet pipe configured to introduce exhaust gas from the engine into the shell, an outlet pipe configured to discharge the exhaust gas out of the shell, and a cap configured to be attached to a narrowed portion of the inlet pipe and control the direction in which the exhaust gas flows out. The cap is provided with an opening through which the exhaust gas passes and which regulates the direction in which the exhaust gas flows out.

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.

An exhaust silencer device which is interposed in an exhaust passage in a vehicle to reduce exhaust noise comprises a sub-muffler which is interposed in the exhaust passage and has an expansion chamber formed therein; an inlet pipe which is airtightly inserted through an inlet opening of the sub-muffler; and an outlet pipe which is airtightly inserted through an outlet opening of the sub-muffler, wherein the inlet pipe and the outlet pipe are formed with openings (small apertures, non-joined portions) only in their upper half area and their lower half area is sealed without having the openings.

A heat management system for air-cooled engines suitable to power yard care equipment or vehicles. The system may generally comprise an engine, a blower configured to blow ambient cooling air across the engine, and an exhaust system comprising an exhaust header and a muffler. The exhaust header has an inlet end which receives heated exhaust gas from the engine and an outlet end fluidly coupled to the muffler. An air control baffle is configured to redirect a portion of the cooling air from the blower towards the exhaust header and the muffler to enhance cooling the exhaust system. The system may further include an outermost protective shield exposed to equipment operators and an inner heat barrier or shield located between the muffler and protective shield. The system is designed to ameliorate both radiative and convective sources of heat transfer to maintain the protective shield at temperatures below established industry standards.

An exhaust apparatus includes a chamber disposed below an engine, an inlet pipe guiding exhaust gas from an exhaust pipe to the chamber, a tail pipe discharging the exhaust gas from the chamber to an outside, a first partition wall partitioning an inside of the chamber to a pair of left and right spaces, and a second partition wall partitioning one of the left and right spaces to a pair of front and rear spaces. Another of the left and right spaces is a first expansion chamber into which the inlet pipe enters. A rear space of the front and rear spaces is a second expansion chamber disposed downstream of the first expansion chamber. A front space of the front and rear spaces is a third expansion chamber disposed downstream of the second expansion chamber, and the tail pipe enters into the front space.

A novel sound absorbing sheet material with a unique combination of micro-louver slit parameters and patterns provides superior noise attenuation and a reduced perforation area (less than 3.5%) to better protect fiberglass insulation when used in a muffler assembly. A muffler assembly is disclosed incorporating the novel sound absorbing sheet as the inner exhaust conduit.

Devices, systems and methods are described for reducing noise emitted from active aerosol and bioaerosol collection devices. The system includes a noise reducing muffler between the collection component and the air mover and a noise reducing baffle at the outlet of the air mover. The muffler reduces higher frequency noises emitted from the air mover inlet while the baffle reduces lower frequency noises emitted from the air mover outlet. Placement of the muffler between the collection component and the air mover eliminates the potential for loss of particles to the muffler prior to collection.

A muffler for receiving exhaust gas from a combustion engine comprises a shell, first and second inlet pipes each having outlets providing exhaust gas to a mixing chamber within the shell, a first chamber and a second chamber positioned within the shell and a pair of communication pipes each including an inlet receiving exhaust gas from the mixing chamber. Each communication pipe includes an outlet providing exhaust to the second chamber. Each of the communication pipes further includes a Helmholtz opening positioned downstream of the mixing chamber. The Helmholtz openings are open to the first chamber.