Influencing Factors Of Longitudinal Impulse And Optimization Of Operating Mode Of Heavy-haul Train

Compared with air transport,sea transport,road transport and railway transport has the advantages of environmental protection,low cost,large volume of transport and less impact of climate change.Among them,heavy-haul transport plays an extremely key role in the safe operation of the national economy.For example,China’s Daqin Line,Wahri Line and other heavy-haul railway lines are the major channels of energy transportation in China,especially during the freezing disaster in south China in 2008 and the nationwide low temperature weather in 2021,coal was continuously transported from Shanxi and Inner Mongolia to all parts of the country,ensuring the sustainable development of the national economy and social stability.However,with the increase of axle load and the number of marshalling,the longitudinal impulse of heavy-haul trains will increase significantly,which will lead to hook breaking and derailment accidents.Therefore,the following questions need to be studied:What factors affect the longitudinal impulse of heavy-haul trains;Under the premise of safe operation,how to optimize the train operation mode,so that the train can arrive on time;ECP(electronically controlled pneumatic braking)technology has greatly improved the braking wave speed of trains.How about the application prospect of this technology in heavy-haul trains.Firstly,according to the train longitudinal dynamics theory,the theoretical model of longitudinal dynamics of heavy-haul train was established,and the multi-body dynamics simulation model was built in the UM software environment.By comparing the simulation analysis data with the experimental data,the error is within a very small range,which proves the correctness of the multi-body dynamics model of the train.Secondly,with the maximum coupler force as the criterion,the longitudinal impulse performance of heavy-haul train under three working conditions of starting,braking and relieving is studied by theoretical analysis and simulation analysis.The results show that:During starting,the more stable the operation is,the less the longitudinal impulse is.During braking,factors such as line slope,braking wave speed,initial braking speed,decompression amount,Loctrol delay and their combinations of different levels have different effects on the longitudinal impulse performance of the train.In remission,the greater the initial remission speed,the smaller the longitudinal impulse.Then,according to the technical requirements of the cycle braking of heavy-haul train in the long distance down ramp,the operating range K275-K325 of Daqin line is selected,and the operation diagram of heavy-haul train is obtained by using the fuzzy control algorithm.The simulation running time is compared with the actual running time,the actual running time is 3200 s,the simulation running time is 3150 s,and the error is 1.6%.At this point,the train longitudinal impulse maximum hook force 687 k N,the maximum hook press force-890 k N,meet the safety requirements of the train’s longitudinal impulse hook force,indicating that the fuzzy control algorithm is correct,provides a way of thinking for the optimization of the operating mode of heavy-haul train.In the end,by establishing the optimized model of heavy-haul train which embedded electrically controlled pneumatic braking system(ECP),study the impact of ECP on the performance of train’s longitudinal impulse,the results show that the ECP system can greatly reduce the train’s longitudinal impulse level,above work provides a thought for the future development of bigger axle load,longer marshalling heavy-haul train in our country.