Research On Driving Conditions And Durability Testing Conditions Of Parts And Components Of A City Bus On A Line In Xi’an

Vehicle driving conditions and parts testing conditions are important input conditions and reference basis for product design and test of automobile and its related parts.They play an important role in the development of vehicle and parts products.Taking some city buses on a certain line in Xi’an as the object of study,in this thesis,the regional driving conditions of the whole vehicle are constructed.According to the built driving conditions and the performance requirements of the whole vehicle design,the parameters of the power system of the pure electric city bus are matched,and the whole vehicle model and simulation are carried out by CRUISE.Finally,Through comparing the service life of motor output shaft under different working conditions,the durability test conditions of automobile parts are screened out.The main work of this thesis is as follows:Firstly,the bus routes of all cities in Xi’an are screened,the data collection is completed and the sample database is determined.The combination of eigenvalues and the number of clusters needed for clustering are determined by cross-test.Using Markov chain principle to complete the splicing of working condition fragments,and by checking the stability of V-A matrix after splicing,the appropriate length of working condition is determined.From the point of view of energy consumption,the representative working conditions of the line are selected from the candidate working conditions,and the average eigenvalue error is tested.Secondly,the parameters of the motor are determined based on the selected representative working conditions and the basic performance requirements that should be met in the design of urban buses.The gear number of the transmission system is determined and the transmission ratio of each gear is calculated.By comparing several common types of power batteries in the market,the selection of power batteries is completed,and the matching of battery parameters is completed according to the mileage requirements of city buses.Thirdly,based on the matched parameters of the whole vehicle and power system,the whole vehicle model of pure electric city bus is constructed by using CRUISE software.The performance of the vehicle model is verified by speed following test,climbing performance test,full load acceleration test and endurance mileage test under 40 km/h constant speed condition.The rationality of the screening method for representative working conditions is verified by using the model.Finally,the screening conditions of assembly durability test conditions are determined from the perspective of user demand.Based on the simulation results of the candidate working conditions,the frontal stress loads on the motor output axle of the sampled vehicle under different working conditions are calculated.The rainflow counting method is used to calculate the stress load,and the service life of the motor output shaft is calculated according to the linear cumulative damage theory.The shortest service life is selected as the durability test condition of the components.