2016 Volume 24 Issue 1 Pages 11-22
Gasoline engines have been required to improve the thermal efficiency and reduce the pollutant emission, and the previous studies were developed by controlling the ignition timing and keeping the constant air-fuel ratio. For further improvement of the thermal efficiency, it is expected to reduce the pressure fluctuations due to the combustion per cycle, which causes to generate the stable combustion field and improve the fuel consumption. Since the pressure fluctuations due to the combustion are significantly affected by the ratio of the residual gas in the cylinder, the present study proposed the method to estimate the ratio of the residual gas, which is defined as the mass ratio of the residual gas and the air-fuel mixture into the cylinder, by using the combustion pressure, and developed the methods to reduce the pressure fluctuations considering the ratio of the residual gas by controlling the ignition timing. Under the experimental condition of the large ratio of the residual gas, it was found that the fluctuations of the indicated mean effective pressure was reduced to more than 20% by using the developed methods.
