The Longitudinal Dynamics Research On The 30000-ton Combined Train

With the rapid development of the national economy,China's railway heavy haul transportation has developed rapidly,since 2003,Datong-Qinhuangdao line opens 10,000 t and 20,000 t heavy haul trains,it makes the annual transportation volume arise from 100 million t in 2002 to 400 million t in 2010,it substantially increases the transportation capacity across the whole line.Despite the transportation capacity constantly increases,but is still fails to meet the needs of the national economy for goods transportation, it needs to improve the transportation capacity further. Increasing train speed and openning density and other measures are restricted by objective conditions,openning the 30,000 t heavy haul trains of improving the traction quality is put on agenda.During the heavy haul transportation,due to the weight and the length increase of the heavy haul trains,braking wave propagation time gets longer,the coupler force increases,the longitudinal impulse of the heavy haul trains becomes the primary issue.There are many factors that affect the train coupler force,including train marshalling,braking performance and characteristics of draft gear,among which the air braking system is the most important.Because of multi-locomotives and the controllable train tail device in heavy haul trains,it is difficult to get the braking performance for the heavy haul trains and this will reduce the analysis accuracy of train longitudinal dynamics.The air braking system performance that is obtained from the train air braking system simulation method based on the air flow theory,unrestricted by the current test conditions,applicable to different train marshallings,test conditions and equipment conditions.The air braking system and longitudinal dynamics system co-simulation software used in the article,while simulating the air braking system performance,calculating the train longitudinal impulse,achieving the simultaneous simulation of braking and longitudinal dynamics,can real-time dynamically simulate and display the whole process of train running,is of great importance for improving the performance of the heavy haul trains'longitudinal dynamics.The article comprehensively compares the coupler force of the 30,000 t heavy haul train under the condition of multi-locomotives and controllable train tail asynchronous action and changing the braking initial speed,in the case of full service application and emergency braking of marshallings:1+1+1+controllable train tail,1+1+1 and 1+1+1+0,the feasible marshalling 1+1+1 which is applicable to the Datong-Qinhuangdao line's 30,000 t heavy haul train is proposed,and studies the influence law of asynchronous time to the coupler force.In addition,takes Datong-Qinhuangdao line's two most difficult long slope intervals'two consecutive sections (k139.9-k155.6) and (k285.3-k305.4) as example,carries on cycle brake simulation calculation,train can pass two long slopes,running speed basically controls within the speed limit.The results show that the longer the lag time of the dependent control locomotives is,the greater the coupler force is,in the case of full service application,the change of dependent control 2 locomotive's lag time has a greater impact than the dependent control 1 locomotive's lag time on the coupler force,the dependent control locomotives brake 5s lagging behind the master control locomotive,the maximum coupler force increases by 82.4%;In the case of emergency braking,the change of dependent control 1 locomotive's lag time has a greater impact on the coupler force,the dependent control locomotives brake 5s lagging behind the master control locomotive,the maximum coupler force increases by 335.9%.In the case of full service application,maximum coupler force is not a threat to the train,in the case of emergency braking,especially the dependent control locomotives having large lag time,there will be a great coupler force,is the dangerous condition of train running,the lag time of dependent control locomotives controlling within 4.8s,the coupler force can be controlled within the acceptable range of 2,500 kN.When passing the long slopes, follows the principle which is "small pressure reduction and reasonably control ease initial speed",4 time and 3 time cycle brake is conducted during the two sections,making the heavy haul train smoothly pass the long slopes.In this paper,the calculation by the simulation software is of great importance to improve the train's economy,security and railway's heavy haul transportation technology.