Study On Analysis Method Of Braking Performance For Multi-axle Automobile Based On ECE Regulation

Braking performance of automobile is important for safe driving and is required specifically by ECE braking regulation. The braking performance analysis of two-axle automobile has been researched deeply. For braking system of multi-axle automobile is more complex than two-axle automobile, it is difficult to analyze the braking performance of multi-axle automobile. Some fundamental researches have been done for the braking performance of multi-axle automobile in recent years, but the conclusions are difficult to be applied in practice. A relatively complete set of analysis methods of braking performance of multi-axle automobile based on ECE braking regulation is proposed in this paper. Research results are as follows:(1) Defects of previous evaluation indicators of braking performance of automobile are pointed out, and a complete evaluation index system of braking performance of multi-axle automobile is proposed.(2) By analyzing the requirements of residual braking performance and emergency braking performance of multi-axle automobile according to ECE braking regulation, analysis methods of residual braking performance and emergency braking performance of multi-axle automobile are proposed respectively.(3) Three-axle automobile is referenced as an example. The formula of parking limit slope of three-axle automobile is derived, and the factors which influenced it are analyzed. On this basis, an analysis method of parking-braking performance of multi-axle automobile is proposed. Additionally, a concept named limit slope efficiency is proposed for the first time, supplementing the indicators of parking-braking performance.(4) Requirements of braking force distribution of multi-axle automobile according to ECE braking regulation are analyzed. Defects of analysis methods about braking performance of multi-axle automobile are pointed out. A method named adhesion utilization coefficient diagram is proposed. A new calculation method of normal reaction force of each axle of multi-axle automobile from ground is proposed. An analysis method of braking consistent of automobile train is proposed based on analysis of causes, harms, solutions of braking inconsistent of automobile train.(5) Requirements of several common tests by ECE braking regulation are sorted out, and test conditions and test methods of each test are given.Finally, according to the analysis method of braking performance of multi-axle automobile proposed in this paper, braking performances of six test automobiles are analyzed and evaluated, to illustrate the whole analysis process of the method, and to verify the correctness and practicability of the method simultaneously.