Optimisation of vehicle transmission and shifting strategy for minimum fuel consumption under EU and US legislated drive cycles

In recent years the importance of reducing fuel consumption and exhaust emissions from road vehicles has become paramount. This is because the exhaust gases contribute to global warming as well as adversely affect the quality of air. Emissions legislation is increasingly stringent and automobile manufacturers strive to mitigate these untoward effects and also improve fuel efficiency with new and innovative solutions. This paper shows that gearbox configuration and shifting strategy can be optimised to arrive at an optimum design, reducing fuel consumption and NOx emissions. Such solutions are based on performance enhancement under regulated test procedures embodied in specified drive cycles, both in Europe and in United States. It is shown that a combined dynamics analysis and multi-objective optimisation can yield optimum gearbox configurations for given vehicles/engines. Furthermore, the results of the analysis can be subjected to a trade-off routine in order to find a near optimal generic solution which would meet the requirement of global design and manufacture, and simultaneously comply well with the differing requirements of various drive cycles.