Study On The Performance Of Brake System For Low Floor Tram

Comparing with other system of rail traffic vehicles,low floor trams have great advantages due to line conditions,operating speed and construction costs and other factors.It has the characteristics of large load,safety and environmental protection,and high cost performance.As one of the key technologies to ensure the safe operation of the train,the braking system has distinct characteristics in braking mode,braking control mode and basic braking device.Therefore,it is of great significance to study the performance of the brake system of the low floor tram,which will provide a theoretical basis for speeding up the localization process of the low floor tram braking system.In this paper,a type of low floor tram is used as the object to analysis and study the braking system for the vehicle.The reference of a low floor tram braking system,and combined with the scheme of braking system of low floor trams at home and abroad,putting forward a new scheme of the braking system consisting of electric braking and hydraulic braking and magnetic track braking.Basing on the principle of energy saving,the regenerative braking is preferred and the hydraulic brake is used as a supplementary.Secondly,the working principle of the electronic braking control unit(EBCU)of the moving and trailer and the working principle of the hydraulic unit of the moving and trailer are described.According to the requirements of braking performance,the key parameters in the braking system are calculated and analyzed.According to the working principle and control strategy of the low floor tram braking system,the AMESim software is used to do the simulation modeling,and the performance of the system is analyzed and studied.To establish a simulation model of each module of the system,including the operation of the electronic braking control unit,fast switch valve,traction control unit,train control unit and braking force calculation model,the fast switch valve of hydraulic brake is preliminarily simulated,and the output is in accordance with the requirements of pre control.And the simulation model of the brake system of the trailer and the whole vehicle is set up.According to the established simulation model,respectively,in emergency braking,braking and safety braking mode,do the simulation under two typical conditions of the train load and overload,the braking performance curves of train speed,braking distance,deceleration and brake cylinder pressure are obtained respectively,and the performance curves are analyzed,which meet the requirements of tram braking performance.Finally,according to the simulation model of the whole vehicle braking system,the effect of the performance parameters of the fast switch valve on its output characteristics is studied,and the optimized parameters are put forward.The optimum opening degree of the opening of the inlet and discharge valve is obtained by the method of multi group valve opening data simulation experiment.Secondly,in view of the oil loss or oil leakage after each hydraulic brake,the influence of the reduction of the accumulator pressure on the pressure of the subsequent hydraulic brake is studied.The pressure response speed of hydraulic cylinder under different pipe length and pipe diameter is studied,and the best value is put forward according to the result.Then,the influence of the constant torque zone and the speed point of the natural characteristic zone on the output pressure of the hydraulic cylinder is obtained by using the integral method.The relationship between the speed light out point of electric power and the excitation current of the motor is discussed,and the proposed value of the speed out point is proposed.