Device for purifying the exhaust gases of diesel engines

Abstract

In a diesel engine provided with a diesel particulate filter 81 and an exhaust throttle valve 9, noise is decreased that is produced when the exhaust throttle valve is returned back to the fully opened state after a diesel particulate filter 81 has been regenerated by oxidizing and removing the particulate matter deposited thereon. The exhaust system of the diesel engine is equipped with the diesel particulate filter 81 and a catalyst 82 on the upstream thereof, and is further equipped with the exhaust throttle valve 9 on the downstream. The diesel particulate filter 81 is regenerated by operating the diesel engine in a state where the exhaust throttle valve 9 is opened to a small degree. When the regeneration has finished, the diesel engine is run at a decreased rotational speed and, thereafter, the exhaust throttle valve 9 is returned back to the fully opened state. When the engine is run at a decreased rotational speed, the pressure in the exhaust system decreases making it possible to greatly decrease the noise that generates at the time of the opening of the exhaust throttle valve 9.

Description

technical field [0001] The present invention relates to an exhaust gas post-treatment device and its control device equipped in the exhaust system of the engine in order to reduce the harmful components contained in the exhaust gas of the diesel engine, especially the particulate matter restricted in the diesel engine. Background technique [0002] As an important part of environmental measures, the regulation of nitrogen oxides (NOx) and hydrocarbons (HC), which are harmful components in exhaust gas, is implemented on vehicle engines. On the other hand, various technologies for reducing harmful components A lot of effort has been put into its development. In particular, regulations on diesel engines, especially diesel engine exhaust gas, have been gradually strengthened in recent years, and there is a tendency to impose stricter regulations in the future. A diesel engine is an engine that compresses air supplied to a cylinder, injects fuel into the high-temperature and hig...

AI Technical Summary

Problems solved by technology

In addition, post-processing devices such as continuous regenerative DPFs have a larger cross-sectional area than exhaust pipes and store a large amount of exhaust gas, which further increases noise.

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