| Heavy-duty truck hub brakes can cause braking accidents due to long-term braking failures.The Ministry of Industry and Information Technology requires a retarder or other auxiliary braking device to be used.Features such as lightweight construction have become the optimal technical solution.However,as China’s research on this technology started late,a large number of core patented technologies are currently held abroad.Therefore,it is of great significance to research and develop engine-assisted braking technology with independent intellectual property rights.This paper invented a reset spool valve engine auxiliary braking mechanism in the cylinder,and used simulation analysis to carry out research and optimization of braking performance,kinematics,dynamics,and reliability of key components,and completed prototype production.A test device for the gas distribution mechanism that can simulate the pressure of the cylinder pressure was developed,and the functions of the auxiliary braking mechanism in the cylinder and the test device were verified.The main contents of the research work in this paper are as follows:(1)Consult the relevant literature,study and absorb the principle of in-cylinder auxiliary braking technology,analyze the advantages and disadvantages of various designs,and summarize the common characteristics of different designs.(2)Establish the one-dimensional simulation platform of engine auxiliary braking performance,study the influence of exhaust valve lift curve parameters on braking power,obtain the most appropriate parameters,and provide the basis for threedimensional model design.(3)Using the advanced technology at home and abroad for reference and avoiding the existing patents,three kinds of in-cylinder auxiliary brake technology schemes with independent intellectual property rights are invented and designed.(4)For a certain type of engine,the three-dimensional modeling design of the auxiliary brake arm in the engine cylinder with reset slide valve is carried out,and its kinematics analysis is carried out to optimize the three-dimensional model parameters.(5)Establish the dynamic simulation model of brake rocker arm,analyze the dynamic characteristics of exhaust valve during braking lift,and optimize the threedimensional model parameters according to the requirements of one-dimensional simulation results.(6)The stress analysis of the key components of the rocker arm mechanism is carried out,and its high cycle fatigue reliability is studied.(7)A test device for the gas distribution mechanism that simulates the pressure of the cylinder pressure was developed,and a dynamic test study of the rocker arm mechanism was carried out to verify whether the in-cylinder auxiliary braking mechanism and the test device designed in this paper meet the design requirements. |
