Because of its vocation, the INRETS carries out a large number of onboard measurements on vehicles running on road, track or dynamometer bench. These are related to the actual use of the vehicle (kinematics followed, consumption, trip duration and length) or to the influence of parameters on consumption (5th gear, electrical consumption, load, rolling resistance). These experiments teach a great deal about actual kinematics representing different types of traffic (urban, road, motorway). A model called SIM has been developed for forecasting consumption of a vehicle and conditions of the use of its engine and transmission for different types of kinematics from a congestive urban cycle to motorway cycle to motorway cycle. The model has been developed in FORTRAN on a SUN station and is now available for ten types of vehicles using four types of internal combustion engine. The average accuracy concerning consumption is about 5% for ECE standardised cycle and stabilised speeds of 90 and 120 Km/h. The information given by the simulation about the actual use of the engine helps to forecast fuel consumption reduction of a parallel thermic-electric hybrid transmission. In this concept the electric motor is used for low required power motion and the internal combustion engine is actuated as soon as the power demand exceeds that of the electrical motor and 200 Kg of Pb/ac batteries showed that a reduction of about 60% in consumption is feasible in urban conditions. The consumption is then shared between fuel and electricity. The use of the model combined to the kinematics representing the actual type of traffic is very precious when studying engine and transmission parameters of a vehicle all over its range of use.
Abstract