| With the development of railway transportation technology,heavy haul technology has received more and more attention.In the case of successively carrying heavy hual cargo trains in various countries,many technical problems have been encountered,especially the problem of large longitudinal impulses.Deterioration of the longitudinal dynamics of the train seriously affects the safety of the train and becomes a further restrict to increase the weight of the train.As an important part of the train,the braking system is the key to affecting the longitudinal impulse of the train.The air brake system has been gradually improved in the long-term research and development,but it can't meet the development needs of today's heavy hual trains,and the ECP brake technology can't be realized in China.In order to adapt to the status quo of China's train haul development and decrease the longitudinal impulse of the train,grouped train electric controlled pneumatic braking system is a new type of braking method being discussed at present.The application doesn't require large-scale transformation of the existing vehicle structure.It is only necessary to add a set of electronically controlled exhaust devices to the train part of the vehicle.In this paper,the TABLDSS simulation system developed by Dalian Jiaotong University is used to study the action mode of the electronically controlled exhaust device after applying the grouped train electric controlled pneumatic braking system and the effective pressure time of the brake cylinder of each vehicle.By calculating the longitudinal impulse and braking distance of C64A,C70,C80 trains in deceleration braking,common full braking,emergency braking,the advantages of the grouped train electric controlled pneumatic braking system for different types of trains with different loads are obtained.During the actual operation of the train,it will be affected by uncontrollable factors.This paper also discusses the influence of the external vehicle variable air brake system and the grouped train electric controlled pneumatic braking system on the longitudinal impulse of the train.The research shows that different types and different heavy haul trains can reduce the longitudinal impulse by using the grouped train electric controlled pneumatic braking system when the speed control brake is applied on deceleration braking,the common full brake and the emergency brake are used,the electro-pneumatic random 4S braking mode is better than the electro-pneumatic sequential 1000m/s braking mode in reducing the longitudinal impulse of trains.but the grouped train electric controlled pneumatic braking system has no effect on the relieving condition.In the deceleration braking,the grouped train electric controlled pneumatic braking system has the greatest influence on the C80 type train,and the coupler force can be reduced by more than 23%;the grouped electro-pneumatic braking system has the greatest impact on C70 trains under common full braking conditions,and the coupler force of each type can be reduced by more than 50%.under the emergency braking condition,the grouped train electric controlled pneumatic braking system has a greater impact on the C80 train,and the coupler force can be reduced by more than 15%.The grouped electro-pneumatic braking system can reduce the braking distance by more than 15%under the condition of speed regulation braking and common full braking conditions,but the effect of braking distance reduction during emergency braking is small.When the train is affected by the ramp,the coupler clearance,and the train pipe pressure gradient,the longitudinal impulse will be more severe,But even in the worst conditions,when the grouped electro-pneumatic braking system is applied,the coupler force can be reduced by at least 20%.60%,55%.The study of grouped electro-pneumatic braking system is suitable for the design of braking system for long and heavy haul trains aiming at reducing longitudinal impulse. |
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