Research On The Hydraulic Auxiliary Brake And Its Self Energy Feedback And Heat Dissipation System Of Passenger Car

With the rapid development of national economy and the improvement of people's living standards,the popularity of passenger cars and commercial vehicles is getting higher and higher.The number of people and the total amount of goods transported by automobile and highway has increased rapidly,which not only facilitates people's life and improves the national economy,but also causes the rapid increase of the incidence of traffic accidents.According to statistics,in traffic accidents,many are caused by vehicle braking problems.At the same time,vehicle rear end collision and vehicle unilateral accident are the main accident forms,so the improvement of brake performance has become an urgent problem to be solved.The state has also issued relevant provisions for auxiliary braking device.Hydraulic hybrid technology has the function of auxiliary braking,and the hydraulic hybrid technology has fast response and high power density.It has more advantages for high frequency and high power energy conversion,which is very suitable for medium and heavy load and frequent start and stop.However,the heat dissipation of hydraulic auxiliary braking system is a problem that should be paid enough attention to.If the hydraulic oil temperature is too high,the efficiency of the hydraulic system will be reduced and the service life will be shortened.Serious will also lead to hydraulic system performance failure,make the installation of hydraulic system machinery can not work normally,and even cause accidents.In the traditional vehicle equipped with hydraulic auxiliary braking system,the heat dissipation device is generally provided by the engine or motor,but this way will cause the consumption of excess fuel.This paper takes a large bus as the research object,and develops a set of auxiliary braking system.At the same time,the heat dissipation of the hydraulic auxiliary braking system is different from that of thetraditional hydraulic auxiliary braking system,which is provided by the engine.The braking energy of the vehicle can be used to heat the hydraulic system to meet the braking requirements of the vehicle and reduce the fuel consumption.In this paper,firstly,the force of the bus when braking,and the heat production and heat dissipation of the hydraulic system are analyzed.The key components of the vehicle and hydraulic system are modeled.The parameters of the key components of the hydraulic system have the greatest impact on the system performance,so it is particularly important to optimize and match the key parameters to improve the system performance.Taking the key parameters of the hydraulic system as design variables,the objective function and constraint conditions are determined according to the mathematical model of the vehicle and the key components of the hydraulic system.The genetic algorithm in MATLAB is used to optimize the key parameters.The best matching parameters are obtained.According to the system configuration and matching optimization parameters of the proposed hydraulic system,the components of the hydraulic system are selected and designed.The three-dimensional drawing and assembly of the whole vehicle and the hydraulic system parts are carried out according to the ratio of 1:1,and the hydraulic system parts are installed according to the three-dimensional graphics,so as to realize the hydraulic auxiliary system and its self feeding heat dissipation system.The simulation model of the whole vehicle and hydraulic system is established by AMESim.The simulation test is carried out under the design conditions.The working state of the hydraulic system is analyzed through the changes of pressure,flow,hydraulic pump / motor speed and vehicle speed in the simulation process,so as to analyze the performance of the hydraulic system.By comparing the temperature changes of the hydraulic oil added with the hydraulic cooling system and without the hydraulic cooling system,it is verified that the hydraulic system can meet the requirements On the basis of the requirements of auxiliary braking device,it can meet the heat dissipation demand.At the same time,NEDC is used to simulate the urban conditions,which proves that the cooling requirements are also met in the urban conditions.