EGR Technology Research For CN4 Light Duty Diesel Engine

As the diesel engine technologies progressively advance forward, the advantages of diesel engines in comparison with gasoline engines, such as fuel economy, efficiency and environmentally less harsh, are getting more emphasized. Diesel engines have been found in a broad range of applications, however, the hazardous polluting substances they emit during operation are the major cau se of atmospheric pollution. Consequently a large part of the society’s concern is drawn to this issue, and engine emission legislations are becoming more and more strict in order to address this problematic matter. China has enforced the GB4 emission legi slations since 2014. There are two main technical approaches worldwide designed for engine emission treatment in order to meet the GB4 standards, the SCR and the EGR approach. For compact engines, when taking into consideration the cost and engine compartment space, a substantial number of engine manufacturers are leaning towards the EGR+DOC+POC approach. It is therefore given that the study into the EGR approach is of great importance to diesel engine technologies.This article attempts to compare and anal yze the differences between SCR and EGR, based on a light duty four cylinder diesel engine with EGR, and proposes methods for meeting the GB4 legislations by means of combustion optimization and systematic optimization of EGR. The main topics are:(1) This study attempts to analyse the different approches to control EGR system, such as mechanical, pneumatic and electric control. The impact of EGR on diesel engine combustion process is dicussed, and the guidelines for choosing EGR type is given. Also the design principle of the EGR system is discussed in detail.(2) An analysis of the combustion characteristics of EGR engines, the optimization and selection of combustion components,preliminarily determine the NOx emission evel.(3) A study into the EGR system, comparison between different EGR valve layouts, the impact of EGR system volume on the performance of the engine at low speeds, and EGR open/close loop control.(4) Matching after-treatment system to the engine, via the optimization and calibration of engine fuel system and EGR system.