Research On Subjective Evaluation Of Powertrain Performance And Brake Performance Of Automobile

In recent years our domestic automobile industry has developed rapidly. But own-brand car enterprises due to their weak foundation of research and development, product performance and brand awareness are not as foreign brands, occupy mostly low-end market, coupled with the overall downward product prices of joint venture, they are facing great pressure of competition. Therefore, how to improve product performance, enhance the competitiveness of the enterprises have been imminent.How to develop a high-performance vehicle is of great significance. Since the chassis performance is crucial to vehicle, the main performance of automobile chassis in the early stages design must be ensured.But in the modern chassis development, higher performance are requirements, in crucial conditions and the high-frequency response, the drive, brake, steering, suspension assembly interaction and mutual influence, separate evaluations on the various assemblies can not meet need. Hence, we must conduct comprehensive performance evaluation to vehicles to meet matching requirements. However, we have not yet got an effective integrity of the objective evaluation method and system.Therefore urgently to establish an objective evaluation system based on the assembly of virtual prototype technology which can optimize and match automobile dynamic performance in the conceptual design stage of new vehicle development. This objective evaluation of the indicators must be able to identify a comprehensive inspection of vehicle dynamics.Chassis dynamics performance subjective evaluation is also a very important work. Definiting product from the beginning of planning or conceptual design phase, selecting the cars of competitors on the market to benchmark, determining the target product development, developing by virtual computer, adjusting to the late, subjective evaluation is absolutely necessary. All automobile companies have developed a set of subjective evaluation system. Own-brand car enterprises in our country, as the late start and technical security and other reasons,the technologies of subjective evaluations mainly rely on foreigns, although some enterprises have their own subjective evaluation methods and indicators, but immature and imperfect.We adopted extracted a strong independence indicators from the subjective evaluation indicators as an objective evaluation indicators, and guaranteed an objective evaluation system for the evaluation of automobile dynamics completeness. Meanwhile the weights of the indicators of powertrain performance and brake performance needed to be obtain.Therefore, the major work of the early stage was to establish automobile chassis dynamic subjective evaluation system, as well as abstracted objective indicators from subjective evaluation. Powertrain performance and brake performance subjective evaluations which are parts of chassis dynamics were selected as this paper research contents, with handling and stability as well as ride comfort subjective evaluation constitute the main body of subjective evaluation of the chassis dynamic, meanwhile the weights of the indicators of powertrain performance and brake performance needed to be obtained. The main part of paper as follows:First of all, information from foreign and domestic automobile enterprises and research units was surveyed and gathered, in order to kown how they carry out powertrain performance and brake performance subjective evaluation of vehicle and how they rate the conduct of the evaluation.And based on SAE 10 points scoring criteria system, our own scoring method was designed.All these composed the foundation of powertrain performance and brake performance of chassis dynamics. Then,based on the information of powertrain performance and brake performance subjective evaluation of domestic and foreign car companies and research units, after analysising the theory of every specific indicator, referring to relevant laws and regulations, and fully discussing powertrain performance and brake performance subjective evaluation with vehicle experts and subjective evaluation engineers,ascertained specific indicators of powertrain performance and brake performance subjective evaluation based on vehicle chassis dynamics. Evaluation also included the evaluation of specific content, how driver to operate, how to choose the road and measurement of the parameters, and a brief description of the dynamic theory.Measurement parameters are proposed for the corresponding objective eigenvalue in order to analysis subjective and objective consistency for the development by virtual computer etc.Then, Analytic Hierarchy Process(AHP) was selected to cope with the indicator weight of subjective evaluation due to AHP suit to change the complicated structure, the relationship between the blurred into quantitative analysis.After building powertrain performance and brake performance AHP models respectively, then requested enterprises experienced subjective evaluation engineers who fully understood AHP evaluation principles and specific indicators based on their practical experiences to give judgement matrixs.On the premise that through consistency test,all weights of the indicators were obtained.This conclusion can be used to evaluate vehicle for benchmark and adjustment,after combining measurement of objective data with subjective evaluation,also can help to develop by virtual computer.Finally, as an example, under this powertrain performance indicators and methods three experienced subjective evaluation engineers were invited to make a subjective evaluation on a real car on test track .Due to the limitation, test was only on high-adhesion road. The indicators and overall powertrain performance evaluation were rated,the weights of the indicators of powertrain performance obtained from AHP were validated and analyzed to lay the foundation for future work.