Study On EMU Operation Problems And Corrective Measures

It is significantly important,for ensuring normal operation of the related equipments and improving reliability and economy of electric multiple unit(EMU for short),to regularly check and fix EMU,which is done as the precondition and foundation of safe and reliable running.As the train set become more complicated and automated,the conventional strategies have not suited the requirements for the maintenance of high-speed trains.In view of this,in this thesis,typical problems of EMU are focused,which occurs in the operation of EMU,and the theoretical analysis and discussion are made on the sway of EMU,wheel wear,failures of traction drive system and causes of the problem with abnormal skidding.Combined with engineering practice,the corresponding countermeasures for the maintenance are suggested.Innovative researches have been conducted as follows:1.Accoding to the data related to the sway caused in the process of the practical application of EMU,the theoretical analysis and comparative study have been carried out,finding out the main characteristics and laws of the sway phenomenon,and the main reasons are obtained,which are the line excitation and the poor contact relationship between wheel and rail.For the main causes of the sway of EMU,the suggestions,that is,the reasonable improvement in wheel-rail matching and the strict management of track irregularity,are presented in order to alleviate and prevent the sway problem of EMU.2.According to the actual data of the operation and maintenance of EMU,the causes of the severe wear on the wheels are presented and preventive improvement measures are proposed.It is the first time to establish a calculation model of life circle cost of the wheel re-profiling,which is employed to calculate the life circle costs with 36 different re-profiling strategies,obtaining the optimal threshold values.3.Fault tree models of traction drive system are proposed,as a result,system failures is associated logically with those of every component,so that the potential causes of the system failures can be discovered.Based on the data of operation problems of CRH1-type EMU,the theories of statistical analysis are employed,and the distribution of the failure probability of traction drive system is derived and demonstrated,determining the main failure modes and causes and suggesting the solutions to the failures.4.For abnormal skidding ensuing from the braking process,the tests of emergency and regular braking,respectively under the conditions of dry and wet rail surfaces,as well as the special tests for simulating benchmark parking,have been carried out for the first time.There are two causes mentioned to explain the relatively longer braking distance.Firstly,the immediate incentive is associated with the special weather conditions,such as fog and rain;secondly,in the skidding process,the velocity difference and the velocity-leap are displayed on the screen and the partial supervision mode for on-board devices is triggered,making the skidding highlighted and abnormalized.