Technology Research On Hydraulic Brake System For Rail Transit Vehicles

With the rapid development of the domestic modern rail transit system,the design and manufacturing technology of modern rail vehicles are also constantly improving.At present,many train factories have introduced modern rail transit vehicles from abroad.Such vehicles include subways,light rails,straddle monorails,new trams,maglev trains,etc.,and the hydraulic brake systems are mostly imported from abroad.In the localization process of hydraulic brake system,the research of its core control technology is particularly important.I am doing research on the following aspects of hydraulic brake control technology:1)On the basis of expounding the research and application state of hydraulic brake system at home and abroad,the composition of foreign hydraulic brake products is introduced,including hydraulic control unit,electric control unit and hydraulic brake clamp.The general configuration and functions of the above three components on the vehicle are analyzed.The hardware design of the hydraulic brake system is studied,including the working principle of the hydraulic control unit,the internal oil circuit design of the main and passive hydraulic control units,the functions of each control valve,the lifting and unloading pressure and the pressure regulation principle.The composition realization of the electric control unit and the design and implementation of the proportional valve drive circuit are studied.2)Innovatively transfer some software logic to the hydraulic brake system according to the traditional air brake application function,including service,emergency,safe,hold,park brake function,different brake mode switching,electro-hydraulic braking force mixing,braking force distribution,external communication port settings,anti-skid logic and faults occur and process in simulation environment.3)Focus on the study of the core characteristics in hydraulic brake unit,the pressureregulating electromagnetic proportional valve through mathematical modeling.The electromagnet model,the valve element force model and the flow model of electromagnetic proportional valve were studied.The flow characteristics and hysteresis characteristics are analyzed.The control method of reducing the pressure hysteresis by applying the dither current and increasing the response speed by applying the dead zone current is designed.The electromagnetic proportional valve is simulated and controlled by PID control.The pressure control technology was further optimized and the brake control effect was improved.The internal structure and working principle of the highspeed on-off valve are discussed.The similarities and differences between the two valve control oil ways and the applicable environment are studied.4)Based on the modern tram with independent wheel,the anti-skid technology of the hydraulic brake system is studied.And the causes and hazards of the skiding are analyzed.Combined with the fact that the fuzzy control does not need a linear model in use,the idea of using fuzzy control for anti-skid control is innovatively proposed.According to the characteristics of independent wheel,a fuzzy controller with wheel speed difference,wheel deceleration and wheel deceleration differential is input to control the pressure coefficient as output.The fuzzy controller is used for anti-skid control and the relevant control results are calculated.5)A hydraulic brake vehicle testbed was built,and the first hardware-in-the-loop test was carried out on the testbed for the software function of Chapter 4.Test the brake function in different braking modes and correct the control parameters.The test results show that the braking force is distributed and the deceleration adjustment achieves the desired effect.The paper learns the design realization scheme and braking force control method of the modern rail transit vehicle hydraulic brake system,and innovatively applies the fuzzy control to the anti-skid control of the rail traffic hydraulic brake,and builds the first domestic vehicle hydraulic brake.Test the results on the testbed.The test results show that the hydraulic brake system can make the clamp output the clamping force according to the brake function,the brake force distribution and the deceleration adjustment achieve the desired effect,and the fuzzy control method can effectively prevent the vehicle skidding.