Design of gear shift map for automatic transmission considering transmission efficiency

Abstract

In accordance with strict fuel efficiency regulations, automobile manufacturers are currently focusing on research and development methods, such as shift map design, for the improvement of fuel efficiency. Traditional eco-shift maps mainly consider only the engine operation efficiency, but mostly ignore the power loss of the transmission. In the case of automatic transmissions, losses in the transmission have a significant impact on fuel economy. This paper suggests a gear shift map design method that considers the effectiveness of an automatic transmission for an enhanced fuel efficiency. A simulator using a parallel hybrid vehicle model and an automatic transmission efficiency analysis model were developed in order to examine the effect of the new eco-shift map. When applying the newly proposed shift map in urban and highway driving cycles, the overall fuel efficiency was improved by 3~4 % as compared to the traditional eco-shift map.