Search Results

The models presented for predicting fuel consumption and emissions for vehicles driven on the road provide the means for averaging and storing results obtained from vehicle tests usually carried out at an emissions test facility to standard and non-standard-drive schedules. For hot start fuel usage and emissions rates the models, in descending order of temporal or spatial resolving capability, include: transient engine mapping (a new model), steady state engine mapping, vehicle mapping, power demand, modal or elemental, lumped parameter (PKE-v) and travel time variants. The engine mapping model is shown to be able to predict instantaneous on-road fuel consumption with good precision (±3ml) for one vehicle over a selected 3.3 km stretch of road. Its emissions rate predicting ability is less satisfactory. When link-by-link fuel is needed the 6 coefficient PKE-v model performs well (R = 0.994).

An upgraded vehicle fuel consumption/emission test facility is shown to be able to simulate on-road performance of cars up to wide open throttle operation. A procedure is described which permits dynamometer loads to be set so as to replicate the on-road, steady speed fuel consumption of each vehicle tested. A test program involving five driving cycles (schedules), three US and two Australian, and a range of other manoeuvres has been devised, to describe a wide range of on-road driving. The tests last one week and have been carried out on a fleet of almost 40 cars. Fuel and emission data has been logged at every half second interval of the tests. The overall test results only have been reported here. It is shown that there is considerable variability in the response of individual cars to changed test cycle. For the Australian test cycle fuel consumption is typically 15% higher than to US 75 FTP city test schedule.

A fleet of 17 utility, van and flat tray bodied trucks has been tested for fuel consumption and exhaust emissions over a range of drive cycles and steady state operating conditions. The influence of vehicle load on the results was included. For each vehicle the tractive force applied by the chassis dynamometer, on which testing was performed, was adjusted to match those found on the road using a new procedure. The fuel consumption results show a downward trend with model year (1.7% annum); about 30% higher petrol use compared with diesel; a cold start penalty of 3 L/100 km and over 2:1 variation for vehicles capable of identical transport task. Exhaust emissions from these rigid trucks were between 3 and 6 times greater than those of the passenger car fleet.