Development Of The Matching Computatition And Evaluation Software For Passenger Cars Using MATLAB

Transportation has been an indispensable part in people’s daily life. This demand has placed the automotive industry at a very important position in the nation’s social and economy systems. Conventional vehicles which equipped with internal combustion engines still have the potential for improvement and they will take up most of the market share in the near and middle future. The matching situation of the powertrain system makes a big difference for vehicle performance. There are many indicators evaluating the vehicle performances, the relationship between them can be positive or trade-off. It is still remains to be discussed about how to choose the representative indicators for consumer’s demands to build up the evaluation system with which the matching condition of the vehicle can be properly judged. Simulation has been widely used in the research and development phase of all kinds of mechanical products.The objective of this study is to construct the computation model for powertrain system, build the indicator system and finally design a matching computation and evaluation program for passenger cars using MATLAB. In this paper, the mathematical model of the powertrain system was built, including the engine, transmission, vehicle body, tire and efficiency/loss. A large amount of data was analyzed and the following principles were found:there is a linear relationship between the mean fuel consumption in real world and the labeled value, it is affected by transmission type and vehicle manufactures; the satisfactory degree of the vehicle fuel consumption is nearly in proportion to its fuel consumption and engine power in which the vehicle class, transmission type and displacement also make some difference. With these principles, the real-world fuel consumption and its consumer satisfactory degree can be predicted by the labeled fuel consumption. It was found through the statistical analyze of theoretical and consumer satisfactory degree that acceleration time can be a good indication for vehicle dynamic performance. This relationship between the 0-100 km/h acceleration time and the consumer satisfactory degree of the vehicle dynamic performance can be linear or quadratic. Satisfactory degree theory combined with linear weighting method and fuzzy theory were used in this paper for the evaluation of the matching. Radar map was used so that the result of the matching can be interpreted intuitively and vividly. The MATLAB software was designed for the matching computation and evaluation processes, including the input module, dynamic computation module, economy/emission computation module and the integrated evaluation module. The accuracy and reliability of this software was tested using the data from a certain type of passenger vehicle. The influences of the power train parameters on the vehicle performances were analyzed. The vehicle performances were compared with different combinations of power trains and engines. The power train parameters were designed and optimized.