Development of small off-road diesel with high-performance and low emission

In order to develop small non-road diesel engines with high-performance and low emission as well, a small non-road direct injection type diesel engine with a single cylinder was taken as the research object. The CAE and CFD comprehensively applied, and the research was proceed with two approaches which were the optimization matching of combustion system parameters and the improvement design of mechanical system. Optimization matching of fuel injection system parameters, combustion chamber and intake swirl ratio were studied by using the multi-dimensional simulation software such as Hydism, Fire and so on. The optimization plan was determined after the effects on combustion process and emission performance were analyzed. The ameliorated design was applied to cylinder block, cylinder head as well as piston, etc. In addition, the finite element analysis software was used. As a consequence, the structural intensity, stiffness and dependability of the diesel engine were enhanced. At the same time, the machine oil consumption reduced effectively. The results of the test showed that, compared with the original engine, the fuel economy and the emission performance were improved effectively. The quantity of CO, HC + NOx and PM reduced by 49%, 58%, 74% respectively, while fuel oil and machine oil consumption reduced by 6.9% and 59%. The emission performance of the optimized scheme was obviously improved which could meet EPA Ⅳ Non-road Diesel Engine Emission Limit well. This paper provides a reference for the development of small high-performance non-road diesel engines.