Study and Simulation of a Hydraulic Hybrid Powertrain

In the agricultural and work machine sectors, the hydro-mechanical transmission competes with traditional mechanical transmission; a tool to improve its competitiveness is the hybridization. The hydraulic branch of the transmission may be integrated with two accumulators which allow the storage of energy derived from braking; the presence of the two hydraulic units facilitates this solution: the hydraulic motor acts as a pump during the braking and as a motor during the starts of the vehicle. This solution appears to be interesting also from the costs point of view, because it does not require a high-level technology. For this reason, in the present work, the hybrid hydro-mechanical transmission is studied with the aim of pointing out its potential for the urban passenger transport sector. At first, a hydro-mechanical transmission for an urban bus is designed; then, the same transmission is modified adding the components for the hydraulic hybridization. After that, the two vehicles is modelled and simulated using the AMESim code, and, finally, compared to each other in terms of energy savings.