EVALUATION OF GEAR-SHIFT STRATEGIES ON VEHICLE FUEL EFFICIENCY AND EMISSIONS USING QUASI-STATIONARY ENGINE MODELING

Abstract

This study aims to evaluate the impact of gear-shift strategies on vehicle fuel consumption and pollutant emissions. By analyzing gear selection during various driving phases, including acceleration, constant-speed cruising, deceleration, and idling, this research seeks to identify optimal shifting patterns that enhance fuel efficiency and reduce emissions. An idealized driving cycle has been conceptualized, encompassing sequences of acceleration, constant speed movement, deceleration and idle periods. The fuel consumption was calculated using a custom-developed utility based on the quasi-stationary consumption characteristics of the engine and the specific technical characteristics of the vehicle studied allowing an accurate estimate of fuel consumption in different speed change scenarios, which is then graphically plotted as a function of the cycle's average speed. The results indicate that adopting optimized gear shift patterns can lead to significant improvements in fuel economy and reductions in emissions. Strategic gear selection during acceleration and deceleration phases was found to be particularly critical in achieving these benefits. The study is based on an idealized driving cycle, which may not capture all the complexities of real driving conditions. In addition, the vehicle model used in the calculation may not take into account all the variables affecting fuel consumption and emissions, such as environmental factors and driver behavior. The insights gained from this research can inform the development of advanced transmission control systems and driver assistance technologies aimed at promoting fuel-efficient and environmentally friendly driving practices. By integrating vehicle-specific technical data with engine iso-consumption maps, this study provides a nuanced analysis of how gear shift strategies influence fuel efficiency and emissions. The choice of gear can influence consumption, with shifting only occurring up to 2nd gear. Replacing 2nd gear with 3rd gear results in excess consumption of 85% due to engine shift in low loads and high revs. The approach offers a valuable framework for optimizing transmission management to improve vehicle performance and reduce environmental impact.