Study On The Effect Of Operating Mode On Longitudinal Impulse Of Heavy Haul Train

With the rapid development of economy,the demand of domestic heavy-duty cargo transportation and international trade volume rises rapidly,it is particularly important to open heavy-duty railway transportation and the heavy railway freight transportation is becoming the new normal.Due to the increasing total traction weight,axle load and length of the heavy-duty freight train,the brake wave transmission time is lengthened.The front and rear vehicle brakes are out of sync,and the coupler force is increased,which makes the longitudinal impulse of the train becomes larger and larger.Excessive longitudinal impulse can cause a series of safety problems such as,coupler breaking,train derailment,serious wear of parts and components.There are many factors affect the longitudinal impulse of train,including grouping,initial braking speed,slope,radius of curve,braking wave speed,braking response time,etc.,therefore,it is very important to analyze the influencing factors of the longitudinal impulse of long and heavy-duty trains.Starting from the two aspects of the longitudinal impulse theory and the establishment of three-dimensional model of heavy-duty trains,this paper analyzes the impact of longitudinal impulse of 20,000 tons heavy haul train under different operation modes.The ECP electronic controlled air braking system is introduced to solve the problem of excessive longitudinal impulse,and analyze the maximum gradient and longitudinal impulse of 30,000-tons train.The main contents of this paper include:(1)Overview of longitudinal dynamics theory of heavy-duty trains.Detail analyzed in kinetic traction characteristics,air braking,dynamic braking characteristics,hooking device,basic resistance and other forces,as well as the causes of longitudinal impulse and the evaluation criteria for excessive longitudinal impulses are analyzed in detail.(2)The Establishment and verification of multi-body dynamics model of heavy haul train.From the perspective of the heavy-duty train body,coupler and wheelset,a simplified three dimensional model is established in UM Input,the simulation analysis of the 10,000-tons and 20,000-tons heavy-duty trains is carried out respectively,and the reliability of the model is verified by comparing and analyzing the test data and the evaluation criteria of the longitudinal impulse of DaQin Railway.(3)Analysis of the influence of different operation modes on longitudinal impulse of 20,000-ton heavy-haul trains.Different grouping of 20,000 tons heavy haul train is carried out,and the most suitable grouping of 20,000 tons train is obtained by simulation analysis,then the longitudinal impulse of 20,000 tons heavy-duty train is analyzed by adding slope,curve radius and braking response time,and the ECP electronic controlled air braking system is introduced to improve the braking speed and the longitudinal impulse of the train.Through simulation analysis,it is found that the good control mode of the train is 1+2+1 grouping,curve radius is greater than 500m,braking response time is 0.7s,braking wave speed is 9000m/s,lower slope is less than 10‰ upper slope is less than 8‰,and initial braking speed is 40-60km/h.Such control mode can improve the running safety of the train.(4)Maximum gradient calculation and longitudinal impulse analysis of 30,000-tons heavy-duty trains.By using the traditional maximum gradient method,the maximum gradient 7.63‰ of five locomotives towing 30,000-tons heavy-duty train is calculated,the ECP electronically controlled air brake system is introduced into the 30,000 tons heavy-duty train,the train's running speed and other conditions are set and the longitudinal coupler force and acceleration of the train are obtained by the simulation analysis,which meets the longitudinal impulse standard of heavy-duty train.