A Power-Split Hybrid Transmission to Drive Conventional Hydraulic Valve Controlled Architectures in Off-road Vehicles:

The Case of a Mini-Excavator

Abstract

In recent years, several disruptive solutions for off-road vehicles hydraulic implements were proposed to increase energy efficiency, many focusing on the reduction of throttling losses. However, the market has showed a limited adoption of such solutions due to high implementation costs and operator's acceptance. Considering these limitations, this paper proposes to adopt a hybrid power-split hybrid transmission between the supply pump and the prime mover, while still using state-of-the-art hydraulic actuation. Such approach results in an independent control of the engine and pump speeds, therefore improving the efficiency of both. The paper describes the potential application of the proposed solution to a small excavator equipped with a load sensing system. The authors developed a simulation model, which was validated against experiments of the baseline machine. The model was used evaluate fuel efficiency gains achieved with the proposed solution, which are estimated in up to 16% for a truck-loading cycle.