Study On Performance Matching Between Power Transmission System And The Whole Vehicle In 12 Meters Urban Bus

With the rapid development of urbanization and the swelling urban population, the main urban public transportation is based on small and medium urban bus. As the small and medium urban bus has low carrying capacity and slow acceleration, traffic jams are common in peak hours. Besides, urban bus is often crowded, lack of comfort. Nowadays, energy saving and environmental protection are highlighted in the field of passenger vehicle technologies. Chinese government has issued stringent regulations for controlling emissions of commercial vehicles and corporations and individuals who operate the urban bus business institute more strict cost-control policies, which poses higher energy-saving requirements on urban bus. Therefore, energy-saving and environment-protection studies are of great significance in large urban bus technology applications.This study is, in the aspects of dynamics and economics, focused on the power-drive performance matching of 12-m urban bus. Main studies are as follows:Firstly, engine selection and power-drive parameter design are studies for 12-m urban bus. Engines 6112 and 6113, which meet Chinese Phase IV emission standard, are used for design of power-drive parameters.Secondly, road spectra of a city’s passenger vehicle route is collected and analyzed. Characteristic parameters of four typical modes, the Adapted World Transient Vehicle Cycle(C-WTVC cycle), and real driving mode of urban passenger vehicles are calculated. The C-WTVC cycles and the real driving modes of the city are found to be highly matched so the C-WTVC cycle is used for design and optimization of the power-drive parameters of the urban bus of the road spectra.Finally, a simulation model of the 12-m urban bus is constructed with AVL CRUISE software. An optimized mathematical model of the power-drive system is established by using engine 6113, with acceleration increased by 4% and economic sacrifice less than 4%. The power-economy curve "C" is applied to seek the optimum speed ratio of the final drive as 4.44. The Design of Experiment(DOE) and the Genetic Algorithm(GA) are adopted to solve the optimize model and to find the optimum solution of the speed ratio of a gearcase as 5.684/3.737/2.394/1.639/1.0. After optimization, the fuel consumption per 100 km of urban bus C-WTVC cycle is 33.88 L with a fuel saving rate of 3.14%, and an improved maximum gradeability by 14.26%.