Protection of the Earth's environment by means of energy saving and cleaning up of air pollution on a global scale is one of the most important subjects in the world today.
Because of this, the requirements for better fuel economy and cleaner exhaust emissions of internal combustion engines have been getting stronger, and, in particular, simultaneous reduction in nitrogen oxides (NOx) and particulate matter (PM) from heavy-duty diesel engines (HDDEs) without degrading fuel economy has become a major subject.
Mitsubishi Motors Corporation (MM) has been selling diesel-powered heavy-duty trucks in the U.S. market since 1985 and has agressively carried out development work for meeting the 1991 model year exhaust emission standards.
In order to achieve the target, much has been done not only in terms of combustion system improvements, including combustion chamber and fuel injection system optimizing, but also in regard to the effects of sulfur content in the fuel as well as oil consumption on exhaust emissions.
Outlines of the emission control technology established for the 1991 and later model year Light and Medium HDDE's are described in this paper.