A method of manufacturing a cylindrical housing of an exhaust-gas treatment unit for vehicles includes providing a flat sheet metal part having at least one embossing, and round bending the sheet-metal part in a round bending tool by displacing the sheet metal part between rolls such that the sheet metal part obtains a cylindrical shape having a longitudinal direction parallel to roll axes of the rolls. At least one elastic roll is used such that the embossing of the sheet metal part is maintained during round bending. The longitudinal edges of the cylindrical sheet metal part are then connected to form a tube. A method of manufacturing an exhaust-gas treatment unit is furthermore shown.

A diffuser is configured for use on a vehicle having an engine and an exhaust pipe. The diffuser includes a conduit with a first end configured to receive exhaust gases from the engine. A diffusion fitting is coupled to a second end of the conduit to receive exhaust gases discharged from the conduit. The diffusion fitting has an outer wall that includes a curved surface. The curved surface is configured to guide the exhaust gases discharged from the conduit about an axis so that exhaust gases exit a first side of the diffusion fitting rotating about the axis.

A vehicular exhaust pipe structure includes an outer pipe extending along a front-rear direction of a vehicle and an inner pipe disposed inside the outer pipe along an axial direction of the outer pipe. The inner pipe is joined to the outer pipe such that a vacuum layer is formed between the inner pipe and the outer pipe. The inner pipe includes a pseudo-cylindrical concave polyhedral shell-shaped part.

In an exhaust muffler using a double communicating tube as a communicating tube between expansion chambers, the exhaust muffler controls exhaust gas so as not to flow directly between intake and exhaust ports of an inner communicating tube and an outer communicating tube to thereby utilize the volume of the expansion chamber sufficiently. On one end side of the double communicating tube facing into a second expansion chamber, a distal end opening of the inner communicating tube functions as an intake port of an inside passage. A closing member for closing an end in the axial direction of an annular passage is provided in or in the vicinity of a distal end opening of the outer communicating tube. An exhaust port for opening the annular passage outwardly in the radial direction is provided between the closing member of the outer communicating tube and a first partition wall.

A silencer duct includes at least one element including a three-dimensional (3D) chamber having a portion that is at least one of non-vertical or non-linear. An acoustic absorbing member is self-supporting such that is may be positioned within the portion to substantially fill the portion, but does not sag or droop over time.

A marine vessel includes a hull, an engine, and an exhaust manifold including four upstream exhaust holes connected to four exhaust ports, respectively, one downstream central exhaust hole defined by two central upstream exhaust holes of the four upstream exhaust holes, two downstream side exhaust holes located downstream of the four upstream exhaust holes in an exhaust flow direction and spaced from and adjacent to the downstream central exhaust hole on both sides of the downstream central exhaust hole, and a water jacket. The water jacket is located in the exhaust manifold such that cooling water flows between the downstream central exhaust hole and the downstream side exhaust holes.

A marine vessel includes a hull, an engine, and an exhaust manifold including four upstream exhaust channels connected to four exhaust ports, respectively, one downstream central exhaust channel defined by two central upstream exhaust channels of the four upstream exhaust channels, two downstream side exhaust channels located downstream of the four upstream exhaust channels in an exhaust flow direction and spaced from and adjacent to the downstream central exhaust channel on both sides of the downstream central exhaust channel, and a water jacket. The water jacket is located in the exhaust manifold such that cooling water flows between the downstream central exhaust channel and the downstream side exhaust channels.

An exhaust purification apparatus includes a connection portion that connects an exhaust manifold to a catalytic converter. The connection portion includes a diffusion portion and a coupling portion. The coupling portion is configured such that a cross-sectional area of a passage of the coupling portion increases from a connection point with the diffusion portion toward a connection point with the catalytic converter. The side surface of the diffusion portion includes a connection surface to which the exhaust manifold is connected, a collision surface with which the exhaust gas that has flowed into the diffusion portion from the exhaust manifold strikes, a first coupling surface, and a second coupling surface. Cross-sectional shapes of the first coupling surface, the second coupling surface, and the collision surface are arcuate. The cross-sectional shape of the collision surface has a smaller curvature than the cross-sectional shapes of the first and second coupling surfaces.