An exhaust gas purification system has a first exhaust gas purification element, a second exhaust gas purification element, a first exhaust gas part flow duct, and a second exhaust gas part flow duct. The second exhaust gas purification element is arranged geometrically after the first exhaust gas purification element. The first exhaust gas part flow duct has a first exhaust gas passage area and the second exhaust gas part flow duct has a second exhaust gas passage area. The exhaust gas passage areas are aligned parallel to a projection plane and the first and second exhaust gas part flow ducts are arranged geometrically one after another. The two exhaust gas part flow ducts are arranged such that a partial flow channel axis that is orthogonal to the projection plane passes through the first and second exhaust gas passage areas.

A catalyst storage case includes a case body having an exhaust passage; and first and second oxidation catalysts disposed in the exhaust passage of the case body. The first and second oxidation catalysts are arrayed in a direction intersecting a direction along which the exhaust passage extends.

An exhaust device includes an expansion chamber that expands an exhaust gas from an engine; a separator that partitions the expansion chamber; and a plurality of catalyst units arranged in the expansion chamber and supported in parallel by the separator. The separator is divided into upper and lower portions through a dividing plane, and the plurality of catalyst units are supported in such a manner as to be clamped from upper and lower sides at the dividing plane.

An exhaust gas sensor mounting structure includes: an exhaust pipe attached to a vehicle engine; a catalyst unit which cleans exhaust gas of the engine; a silencer connected to a downstream portion of the exhaust pipe; and an exhaust gas sensor which detects a prescribed component of the exhaust gas; at least part of the catalyst unit is located in the silencer; at least part of a pipe that is connected to a downstream end portion of the catalyst unit extends alongside an outer surface of the silencer; and the exhaust gas sensor is attached so as to penetrate through an outer wall of the silencer and a wall of the pipe.

A mixing apparatus for mixing a precursor substance of a reducing agent with exhaust gas, having a housing that provides a mixing chamber and a silencer. The housing inlet side has an inlet connection for exhaust gas and an outlet side having an outlet connection for reducing agent intermixed with the exhaust gas to be discharged. Longitudinal axes of the inlet and outlet connections are offset and parallel relative to one another. An introduction device introduces a precursor substance of the reducing agent and is positioned at the inlet side in a region of the outlet connection longitudinal axis. A length of the housing between the inlet and outlet side at least 1.9 to 7 times a diameter of the inlet connection. A width of the housing is maximally 3 times the diameter of the inlet connection.

A controlling method of exhaust gas purification system to which a lean combustion engine is applied and an LNT device, a DPF or an SDPF, and an SCR device are provided includes detecting vehicle information and determining whether the vehicle information satisfies nitrogen oxide desorption condition of the LNT device; desorbing the nitrogen oxide until the nitrogen oxide of the LNT reaches predetermined reference amount through engine rich combustion when vehicle information satisfies the nitrogen oxide desorption condition of the LNT device; injecting urea to purify the nitrogen oxide after a first period after ending of desorption of the nitrogen oxide of the LNT; desorbing sulfide of the LNT through the engine rich combustion; and injecting urea to purify the nitrogen oxide after a second period after ending of desorption of the sulfide rich combustion of the LNT.

An exhaust after-treatment assembly for an engine system is provided. The exhaust after-treatment assembly includes a housing having an inlet port, an outlet port, a catalyst disposed within a cavity defined by the housing, and a muffler assembly disposed within the cavity downstream of the catalyst. The muffler assembly includes one or more baffle plates disposed longitudinally spaced from one another within the housing to define at least a first resonator chamber and a second resonator chamber. Each of the baffle plates defines an openings aligned to one another about a longitudinal axis of the housing. Further, a resonator tube extends through the openings of the baffle plates and includes an inlet, a perforated portion and one or more outlet ports formed in a wall of the resonator tube. The perforated portion and the outlet ports, respectively in fluid communication with the second resonator chamber and the first resonator chamber.

A V-type engine includes an engine body including a crankcase configured to rotatably support a crankshaft, and a first and second cylinder banks extending from the crankcase, an exhaust collecting pipe connected to the first and second cylinder banks, a catalyst accommodated in the exhaust collecting pipe, and a muffler detachably connected to the exhaust collecting pipe, wherein the catalyst extends in a height direction of the engine body from a base end side of the first cylinder bank to a distal end side of the first cylinder bank.

The temperature of exhaust gas discharged from a compact air-cooled engine used as a power source for an engine-driven working machine is reduced. An engine has a muffler mounted directly to the exhaust opening of the cylinder, and a resin muffler cover covering the muffler. An exhaust gas restriction member is provided to a wall surface of the muffler, and two exhaust passages serving as outlets for exhaust gas are formed in the exhaust gas restriction member. The exhaust passages are arranged independent of each other, and the streams of discharged exhaust gas are discharged to be slightly separated from each other as the streams flow away from the exhaust openings. The separated streams of discharged exhaust gas form a negative pressure space between the streams promoting the introduction of a cooling air stream into the negative pressure portion. Thus, the temperature of the exhaust gas can be reduced.

An optimized structure for an integrated catalytic muffler is provided to purify exhaust gas from an engine and reduce noise when the exhaust gas flows to the rear of a vehicle. The structure includes a case having an inlet and an outlet, and an SCR catalytic unit that is mounted to the case. Particularly, a portion of the SCR catalytic unit is inserted into the case and the remaining portion is exposed out of the case. The SCR catalytic unit is coupled to the case by bolting or clamping. Accordingly, the production cost and weight are reduced, and maintenance and repair are facilitated.