Evaluation of a hybrid hydraulic launch assist system for use in small road vehicles

Hybrid hydraulic launch assist (HLA) vehicles capture energy during vehicle deceleration by compressing fluid in a hydraulic accumulator system. The hydraulic accumulator system can then be used to provide torque at a subsequent vehicle launch. HLA systems are usually aimed at heavy vehicles which have a large amount of kinetic energy available for capture. This article, however, discusses the application of HLA systems on small road vehicles in urban driving conditions by modeling and simulation. The results show that fuel economy savings are not as high as those previously predicted, although many opportunities for system improvement are highlighted by the research approach. It is concluded that with further, more specific, research and development, the HLA system could have a valuable roll to play in the future of hybrid road vehicles.