A Research On Auxiliary Braking System Of Heavy Duty Commercial Vehicle

This thesis focuses on matching design method of auxiliary brake system of heavy duty Commercial vehicle, and the influence of auxiliary brake system on temperature and wear of brake shoes is included.With development of road and improvement of transportation efficiency of heavy duty truck, benefits of auxiliary brake system are more and more realized. Auxiliary brake system can improve safety, reduce maintenance cost and environment pollution. Regulations on Auxiliary brake system implemented in China and Europe are sorted out in this thesis, and types, working principles, control methods of Auxiliary brake system are classified. Investigations of configuration and application are carried out, technology trends and short comings of domestic researches are concluded. The research of this thesis emphasize matching design method and quantitative analysis method of the influence of auxiliary brake system on temperature and wear of brake shoes.A study is carried out to get statics result of slop distribution of mountain road, performance requirements are put out. And the requirements are made the base of configuration design and brake torque distribution for the hand lever positions. Bench tests are conducted to get characteristics of engine brake, exhaust brake, hydraulic retarder. Based on regulations, road slops, braking performance of configurations of a truck are evaluated. Hand lever positions and the brake torque assignments is decided.A method is set up to evaluate influence of auxiliary brake system on temperature incensement and wear of brake shoes. The base of the method is math model of temperature and wear of brake, which base hypothesis is that wear is in proportion to energy the brake absorbed. Test results of brake shoe wear, braking force distribution, coefficient of heat transfer, and typical downhill driving condition are presented. Math model is validated through Type I test, and simulations are conducted then. Differences of temperature rising and brake wear of brake when with/without auxiliary brakes is simulated, and discussion is carried out, a quantitative evaluation is given, which can explain why the actual durability is far short then expected, and improved that auxiliary brake system can play a great role in reducing brake wear.Matching design method in this thesis can be used to evaluate performance of selected auxiliary brake system in vehicle design process, and analysis methods of influence of temperature on brake wear make quantitative evaluation possible for a certain working condition. Test methods in this thesis can be used to validate performance of service brake and auxiliary brake, or acquire parameters for math model. Type data and conclusions in this thesis can be used to analyze and solve problems in braking.