Abstract
A mathematical model of the vehicle resistance has been developed to support the target setting of fuel economy and its deployment as well as to support the related problem solving activity. Having as input the coast-down test data of several weight states, the model can accurately break down the vehicle resistance. The resistance model has 3 components of the resistance and inside them it has 7 variation coefficients. Each component of resistance has its calculation model. By using each calculation model. we can get the variation coefficients by solving differential equations having as boundary conditions the coast down test data of several weight states, so we get firstly the calculation model for every components resistance and then the vehicle resistance model. But there are still some limitations for this study now, coast-down test results deviation should not be too large, otherwise the solving result of variation coefficient of the model is not accurate. Therefore, we need to take care the condition of experiment, such as weather factors, test site effect, the vehicle state, is the same during all tests, Besides, at the time being, the model does not consider yet the influence of drive shaft layout angle variation in different weight states . The vehicle resistance model has proved to be accurate and relatively easy to manage, besides it requires only tests that are already normally done for fuel economy and related performance. In GAC has proved to be effective and now it is part of our development process.
KEYWORDS - fuel economy, vehicle resistance model, coast-down test, resistance curve, tire rolling resistance