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This paper analyzes quantitatively mechanisms and its effects of reducing simultaneously NOx/fuel-consumption taking the focus on torch-jet lean combustion control modeling in a pre-chamber type stratified-charge approach with actual Honda CVCC engine test examples. For analyzing the NO x /fuel consumption reduction mechanism and effects, so-called phenomenological modeling centering around torch-flame-jet behavior are examined with varying the design factors such as auxiliary chamber volume/torch nozzle area. Then, main physical features and those characteristics of torch-flame-jet such as the combustion pressure rise histories in pre-chamber, penetration length/volume/speed of torch-jet in lean mixture of main chamber, lean mixture shear-flow entrainment and turbulence enhancing effects induced by torch-jet are computed with numerical methods and those various effects for the lean ignition/combustion are examined.

Two-stroke engines are being utilized in large numbers as small utility, lawn and garden equipment engines. The following two subjects were examined with regards to exhaust emission control. The first subject was to compare the theoretical values of a combustion model simulation with the experimentally measured values of the base line emission of two-stroke volume as follows in detail. Considering high short-circuiting and residual gas characteristics peculiar to two-stroke engines, comparison analysis between measured exhaust emissions and calculated values by a thermodynamic combustion model simulation. Comparison analysis of the trapping efficiency-corrected HC, NOx, CO mass emission rates by the fuel flow and the fuel and air flow method. Analysis of influence to engine power and mass emission rates by the cylinder thermal load change with varing air-fuel ratio of the charge mixture.