The Study On Cooling Circulation System Of Braking Drum Of Commercial Vehicle

As important tools for transportation,commercial vehicles have brought a great convenience to people's life.At the same time,braking performance,as one of important performance of vehicles,has a great impact on traffic safety.In particular,for the high quality or long time running commercial vehicles,the thermal recession of the braking drum is often an important source of traffic accidents.Today's society is facing the problems of environmental pollution,energy shortage,and the country issued a call for energy conservation and emissions reduction.Lightweight has become the trend of the development of automobile industry.The cooling circulation system designed in this thesis will reduce the weight of the vehicles to a certain extent,and can improve the heat resistance performance of the vehicle.The innovation of cooling circulation system is that a sealed water jacket is designed in the gap between the braking drum and the wheel hub,which can realize the recycling of cooling water.Taking a braking drum as the research object,built the geometric model of the cooling circulation system by CATIA,and expounded its working principle.This article solved several key problems of the cooling circulation system,the design of the dynamic seal and the calculation of leakage,the calculation of the parameters of the electric pump,the calculation of the ideal volume of the cooling water tank.By comparing with the traditional cooling methods,this thesis estimated the economic benefit of the cooling system.Based on the braking performance of the vehicle,the thermal degradation mechanism of the braking drum is analyzed.Combined with the requirements of the national standard against the thermal degradation,this thesis analyzed that the temperature is an important factor to determine the thermal recession and according to the characteristics of the material,the evaluating temperature of thermal recession of the braking drum with cast iron is put forward.From the point of heat transfer,this thesis analyzed the principle of heat generation and heat dissipation.Established the heat balance equation of braking drum and heat conduction differential equation,and achieved the mathematical model of the braking drum temperature.This thesis analyzed braking drum surface temperature distribution under the condition of continuous braking in 10% grade downhill continuous brake using the finite element software Flo-EFD,and indicated whether the thermal depression of the braking drum has occurred.Then calculated the surface temperature of the braking drum under different braking speeds and different cooling water flows,and simulated the relationship of surface temperature of the braking drum,the braking speed and cooling water flow by MATLAB.According to the proposed the temperature thermal recession,analyzed the thermal recession of the braking drum under different conditions,and obtained the optimal flow rate of cooling water.This thesis introduced the electric control device of the cooling circulation system,explains the structure and working principle of the electronic control device.In order to realize the real time control of cooling water,the working principle of the motor is analyzed,and the working principle of the PWM controller is analyzed.Finally,this thesis gave the program structure diagram of the electronic control system.