Study On The Dynamic Performance And Economy Of Engine XD260N5 On A 12M Rear-Mounted Bus

Natural gas engines are replacing the traditional diesel engines because of their high cleanliness and low emissions of harmful substances. As their application to city buses can improve current environmental pollution problems efficiently, natural gas powered buses have achieved a quick application and development both in China and abroad. XD260N5 is a new Euro V natural gas engine developed by**** company on the basis of the diesel engine. Since sufficient Theoretical research and empirical data on its matching to vehicle power transmission system is not available, the application and promotion of this engine model is hindered. For this reason, the study on the dynamic performance and economy law of the matching between this engine and the power transmission system is very important for its application and promotion.To study the dynamic performance and economy of engine XD260N5 on a 12m rear-mounted bus, we adopted numerous methods such as modeling and simulation, road test and optimization analysis. According to indices of the Vehicle dynamic performance and fuel economy. Using the AVL-Cruise software, we set up vehicle models to do simulation analysis of maximum speed, slipping distance, acceleration time of direct gear, acceleration time of starting, maximum gradeability, maximum power factor, constant hundred kilometers gas consumption, and comprehensive hundred kilometers gas consumption. We also did field tests to verify the rationality of the simulation results. Based on the simulated calculations and field tests, we got optimal solutions on reducing fuel consumption with good dynamic performance. We matched gearboxes QJ1205 and QJ805 with 6 gear ratios to get 12 dynamic trains. Then we compared and analyzed the 12 dynamic trains in terms of dynamic performance and economy through the DOE function of AVL-Cruise. We found that when a 5-gear QJ1205 gearbox and a 5.125 speed ratio rear-axle (24F4-00005) are adopted, the gas consumption can be reduced to a lower level, while the dynamic performance as well as economy can reach expected goal. Based on matching optimization, this paper makes a research by contrasting the advantages and disadvantages in power performace & economy when XD260N5 engine replaces the original XD240-50 diesel engine to be applied to 12m bus.The results suggest that engine XD260N5 is quite suitable to this 12m bus model, with high vehicle power reserve coefficient. By adjusting parameters of the transmission system components, it can satisfy requirements for high dynamic performance needed by hard road conditions and requirements for low gas consumption needed by customers’sensitive to gas consumption. XD260N5 engine replaces the original XD240-50 diesel engine to be applied to 12m bus(with the same configuration), which not only can reduce the emission of exhaust gas, but also can improve its power performance and economy.The results of this paper can be regarded as a specification to guide automobile manufactures when they do the lectotype design of engine XD260N5 and the power transmission system of the 12m rear-mounted bus.