A numerical model for the simulation of Diesel/CVT power split transmission

This paper presents a steady-state numerical model of a power split hydro-mechanical input-coupled transmission for off-road vehicles. In this kind of transmissions the combustion engine is connected to a planetary and to a hydrostatic unit. Depending on vehicle speed and power request, the power is transmitted either hydrostatically or mechanically, or in both ways. The performance of the Diesel engine has been simulated in a simple manner by means of a look-up table, based on the specific fuel consumption map; a similar approach has been adopted for the efficiency of the hydrostatic units. The code is able to predict the overall efficiency of the powertrain, while highlighting the contributions of the hydrostatic path, of the mechanical path and of the engine. The results show how the code can be used both for locating the optimum operating point, as a function of the specific duty, and for analysing different configurations of the transmission.