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Mankind developed and enjoyed the automobile civilization, and has lauded the prosperity that it brought about. Commercial vehicle launched the heavy duty diesel engine have been contributing by main transportation system for development of society in the world. However both the local and global environment issues appear depend on the life of mankind, in the world. Especially, global warming is the most stringent issue for our life on the earth. We human beings must lay our existence on the line, and call upon expertise to create solutions for this situation. Diesel engine has great potential for the global warming compatibility by it's high thermal efficiency and diesel vehicle is expected to conserve the environment and to improve the fuel saving for keeping resources in the world. This paper introduces the surrounding of the automobile, such as exhaust emission regulation for heavy duty diesel vehicle, amount and contribution of CO2 emission and noise.

Diesel Particulate Filters (DPFs) having an effectiveness of around 90% reduction of particulate matter (PM) are an essential after-treatment technique in order to meet upcoming PM regulations (Japan2005, Euro4, US07), which are all increasingly stringent. The continuous-regenerating DPF system [1] has been drawing particular attention, because it is possible to significantly simplify the system and reduce costs. The study presented herein investigated the application of a continuous-regenerating DPF system to commercial vehicles. Since exhaust temperatures that are encountered during a significant portion of engine operation are too low to initiate oxidation of PM, a continuously regenerating DPF must employ an oxidation catalyst. However, when the basic characteristics were investigated, an adequate PM oxidation rate was not obtained during city mode operation, during which the exhaust temperature was notably low.