| As consumers’ economical strength continue to rise,their requirements on vehicle handling performance have improved constantly,and as an important part of handling performance,braking sensation is gaining increasing attention.In this paper,we put forward the test criterion,evaluation method and evaluation standard of braking sensation specially according to human,vehicle and environment.Through the comparison of professional evaluation experience and objective experimental data,and quantify the comparison to specific vehicle experiment parameter,forming the evaluation method of braking sensation,which will provide the theoretical guidance to satisfy the needs of consumers.On the basis of domestic and international evaluation and related research of breaking sensation,this paper presents the evaluation method based on the correspondence of objective parameters and subjective evaluation.By testing bench and real vehicle,we can obtain large amount of real-time experimental data of brake pedal force,brake pedal stroke,brake acceleration,brake disc temperature,braking speed differences and the brake noise.By means of High order Fourier data statistical method,the clutter,impractical and random data gained during experiment can be got rid of.To reflect the regulation of data change,we simulate and fit the remaining data according to mathematic statistical methods.In the light of many factors’ effect on the contact relation between brake disc and friction plate like material properties,environmental temperature and humidity etc,we build the simplified mechanical model of brake disc through mechanics analysis methods to research on the generation of brake noise,which is using linear spring to simulate the surface contact stress.Lastly,the result of test is analyzed and researched with the combination of fitted curve and corresponding database and the objective evaluation of professional appeasing personnel,through which,we set up the evaluation criterion respectively and discuss the occurring law of brake noise.Particularly,we classify the urban braking conditions into 4 categories:urban congestion,urban general conditions,urban suburban conditions,urban high-speed working conditions and statistic analysis them respectively.In the mean time,we propose a method of using brake load index to reflex the braking system and urban traffic conditions work intensity.In the process of researching braking sensation,we mainly use brake pedal force,brake acceleration and so on to describe and analyze the working condition,which is also regarded as a appraising indicator of vehicle braking system.And then,we can obtain the vehicle index needed for braking sensation under urban braking conditions,this index will provide correlative criterion for standard test.Meanwhile,we establish test specifications of working conditions and evaluation criterions of brake noise according to the combination of bench test and related operation conditions,the generation time of brake noise under urban operating conditions,the temperature and frequency statistics of brake discs and the frequency and decibel of noise. |
