The exhaust of diesel engines, gasoline engines, and other internal combustion engines includes, for example, carbon monoxide (CO), unburned fuel (HC), nitrogen oxides (NOX), particulate matter (PM), and other constituents. The internal combustion engines are mounted with exhaust purification systems for removing these constituents.
In the prior art exhaust purification systems, it is known to arrange an addition valve which feeds fuel or another additive at the upstream side of the catalyst which purifies the exhaust. By feeding an additive from the addition valve into the exhaust, it is possible to feed an additive to the catalyst.
Japanese Patent Publication No. 2009-156067 A1 discloses an exhaust gas purification system of an internal combustion engine which is provided with a fuel additive valve which adds fuel to the inside of an exhaust pipe. This publication discloses that an additive pool which pools the additive is arranged inside of the exhaust pipe through which fuel which has been injected from the fuel addition valve runs. It discloses that the additive pool be changed in area which receives the additive in accordance with the engine operation. It is disclosed that in this system, atomization of the additive can be promoted even if space for sufficient mixing cannot be secured between the fuel addition valve and the catalyst.
Japanese Patent Publication No. 2007-514104 A1 discloses an exhaust mechanism of an internal combustion engine for lean burn use which is provided with a particulate filter and a deflector which is arranged at the inlet of the particulate filter and which deflects at least part of the exhaust which flows through the exhaust mechanism. Further, it is disclosed that the deflector is formed into a frustoconical shape, has an upstream end which has a first sectional area and a downstream end which has a second sectional area, and has a second sectional area larger than the first sectional area.
Japanese Patent Publication No. 2009-030560 A1 discloses an exhaust purification system of an internal combustion engine which is provided with a reduction catalyst and a reducing agent injector. This exhaust purification system provides an exhaust introduction chamber at the upstream side of the reduction catalyst. The exhaust flows into the exhaust introduction chamber. The inlet side of the exhaust passage in which the reduction catalyst is arranged is extended toward the inside of the exhaust introduction chamber. At the end of the extended exhaust passage, a cover member in which a through hole for exhaust is provided is arranged. In the exhaust introduction chamber, a reducing agent injector is arranged. It is disclosed that the cover member includes a mixer for mixing and dispersing the reducing agent and exhaust. In this exhaust purification system, it is disclosed that it is possible to uniformly disperse the exhaust in which the reducing agent is mixed and feed it to the reduction catalyst.