| The optimization matching of automobile transmission is to ensure the engine could always run near its ideal working area. In this way not only can we make full use of the engine's best performance, alleviate the abrasion, lengthen the useful life span and reduce fuel consumption, but also acquire better emission performance. It is of great significance for easing contradiction between the total fuel consumption and the shortage of fuel supply, which is caused by the rapid growth of car ownership. It is also important in controlling vehicle's exhaust emissions to pollute our environment.This paper derives from the key scientific and technological project of Zhejiang province:"Technology and application of digital design for multi-vehicle sharing chassis platform" (2008C01002). Its research direction is automobile transmission's digital design and parameters optimization. It focused on solving the optimization matching problem between engine and transmission, and provided theoretic basis for chassis's digital design system. This paper also analyzed various factors affecting the automobile performance at the beginning of design, thus speeding up the development process of new chassis and decreasing cost.Main contents of this paper are as following:(1) The research development of automobile transmission optimization matching was presented. Then this paper introduced multi-objective optimization and multi-objective evolutionary algorithm, the development, characteristics and operational processes of genetic algorithm, and analyzed its application in multi-objective optimization problems. Those are theoretical basis of a new multi-objective optimization method to be put forward for automobile transmission.(2) The external characteristic and universal characteristic models of engine were established, and their calculation functions were fitted. Then this paper summarized the evaluating indicators of automobile performance, and established those indicators' mathematical models using simulative methods. The automobile's shift schedule and the dealing method of vehicle inertia have been given.(3) Based on ADVISOR's (Advanced Vehicle Simulator) hybrid simulation theory, this paper analyzed and put forward a new model building method using ADVISOR's background functions for automobile transmission optimization. By doing so, a combined optimization and simulation model with genetic algorithm and ADVISOR has been built based on GATBX (Genetic Algorithm Tool Box) and ADVISOR's background functions. Three objective functions of automobile transmission matching including dynamic, fuel economy and emission performance were integrated into one objective function by weighting coefficients. Simulation example showed that this method could effectively improve vehicle dynamic, fuel economy and emission performance, and extend ADVISOR's optimization analysis functions at the same time.(4) In order to compare the overall performance of original transmission with the optimal transmission, this paper established a calculation model of the example vehicle in CRUISE software. Changes in the relationship between the final drive ratio and performance of transmission was revealed by ADVISOR's Parametric Study and CRUISE's Matrix Calculation.
|
PDF Full Text Request