Modification of four-stroke engine for operation in two-stroke cycle for automotive application

Abstract

The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles. The main disadvantages of two-stroke engines such a big fuel consumption and big emission of hydrocarbons or carbon monoxide can be reduced by new proposal of design of two stroke engine based on four stroke engines. The paper describes the operation of high supercharged spark ignition overhead poppet valve two-stroke engine, which enables to achieve higher total efficiency and exhaust gas emission comparable to four-stroke engines. The work of such engines is possible by proper choice of valve timings, geometrical parameters of inlet and outlet ducts and charge pressure. The engine has to be equipped with direct fuel injection system enabling lower emission of pollutants. The work is based on theoretical considerations and engine parameters are determined on the simulation process by use GT-Power program and CFD program for different engine configurations. The initial results included in the paper show influence of valve timing on engine work parameters and predicted exhaust gas emission. The simulation results show that the nitrogen oxides are considerably reduced in comparison to four-stroke engines because of higher internal exhaust gas recirculation. The innovation of this proposal is applying of variable valve timing with turbocharging system in the two-stroke engine and obtaining a significant downsizing effect. The conclusions shows the possibilities of applying two-stroke poppet valve engine as a power unit for transportation means with higher total efficiency than traditional engines with possible change of engine operation in two modes: two- and four stroke cycles.