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Diesel emissions are significant issue worldwide, and emissions requirements have become so tough that. the application of after-treatment systems is now indispensable in many countries To meet even more stringent future emissions requirements, it has become apparent that the improvement of market fuel quality is essential as well as the development in engine and exhaust after-treatment technology. Japan Clean Air Program II (JCAP II) is being conducted to assess the direction of future technologies through the evaluation of current automobile and fuel technologies and consequently to realize near zero emissions and carbon dioxide (CO2) emission reduction. In this program, effects of fuel properties on the performance of diesel engines and a vehicle equipped with two types of diesel NOx emission after-treatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined.

A low-temperature, premixed combustion concept, called Modulated Kinetics (MK) combustion, has been developed that reduces emissions of nitrogen oxide (NOx) and smoke simultaneously. This new combustion concept requires heavy exhaust gas recirculation (EGR) to reduce the NOx emission and combustion noise. However, there is an interaction between the effects of controlling exhaust gas recirculation (EGR) and the variable geometry turbocharger (VGT). This makes controlling both the EGR rate and air mass flow rate more difficult under transient operating conditions. Therefore, the authors investigated a cooperative control of EGR and VGT in an effort to control the accuracy of both the EGR rate and the air mass flow rate. This paper presents an approach through the application of a control system CAD program and rapid prototyping tools to improve transient operating states by referring to a model-based EGR and VGT control algorithm.

Diesel engines have attracted more attention in recent years as one means of reducing carbon dioxide (CO2) emissions from motor vehicles. One of the major issues for diesel engines is exhaust emissions performance. Diesel engines also face various difficulties in providing the driving force demanded by the driver because of their greater inertia than that of gasoline engines. Meanwhile, continuously variable transmissions (CVTs) have been popularized as gearboxes that execute ratio changes continuously without generating shift shock. The aim of this research is to achieve higher levels of drivability and exhaust emissions performance by mating a CVT to a diesel engine and making maximum use of the continuous ratio change capability. An integrated engine-CVT control algorithm that can freely set the driving force and also the engine operating conditions for generating that driving force has been developed through this study.

An exhaust gas recirculation (EGR) system that recirculates a portion of the exhaust gas back to the intake system is effective in reducing nitrogen oxide (NOx) emissions from diesel engines. However, improved control accuracy over the EGR flow rate is required, because an excessively large flow rate causes emissions of particulate matter (PM) to increase. In recent years, direct injection (DI) diesel engines have also been used on ordinary passenger cars, because their fuel economy is superior to that of indirect injection (IDI) diesel engines. Since DI engines are more sensitive to the EGR flow rate than their IDI counterparts, improving the accuracy of EGR flow rate control has become even more significant. This study concerned an EGR control algorithm based on the results of calculations performed with an engine model capable of representing the dynamic states of the intake and exhaust systems.