Small bore diesel engines often adopt a two-valve cylinder head and a non-central injector layout to expand the port flow passage area. This non-central injector layout causes asymmetrical gas flow and fuel distribution, resulting in worse heat losseses and a less homogenous fuel-air mixture than an equivalent four-valve cylinder head layout with a central injector. To improve these problems Toyota applied a new concept which was characterized by tapered shape design on the upper portion of the piston and low compression ratio to achieve more homogeneous gas flow and fuel-air mixture. This paper describes the impact of new combustion concept and the mechanism of the improvement by 3D-CFD analysis and optical measurement.
Low Cooling Losses and Low Emission Analysis of Small Bore Diesel Engine Combustion
Sae Technical Papers
JSAE/SAE 2015 International Powertrains, Fuels & Lubricants Meeting ; 2015
2015-09-01
Conference paper
English
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