Research Of The Evaluation Of Automobile Ride Comfort And Its Application In Hatchback Cars

Automobile ride comfort is to maintain a certain comfort under the vibration circumstances while driving for passengers, but also to maintain a good condition for goods. Since ride comfort is evaluated based on passengers'comfort performance, it is also called riding comfortableness. With the continuous development of the highway and the speed improvement, automobile ride comfort which becomes increasingly important is not only a main performance for the modern high-speed, high-efficiency automobile, but also an important performance index which obtains advantages over congener cars in the market competition.Automobile ride comfort depends not only on the vibration characteristics of vehicles, but also on human's response to vibration. Therefore, the evaluation of automobile ride comfort is a very complex process, and the establishment of a scientific evaluation system and method is extremely important. This thesis is aimed at making an intensive study of commonly used evaluation methods of automobile ride comfort in order to provide appropriate evaluation methods for evaluating the actual vehicle ride comfort. The main contents and conclusions are as follows:(1) Study on the evaluation method of automobile ride comfortThe evaluation methods of pulse input and two evaluation methods of random input including the evaluation methods based on ISO2631 and power absorption method are carried out an in-depth research and summary.Two evaluation methods aimed at pulse input and random input are studied and summarized in depth. The evaluation method of the vehicle general vibration comfort, which combines root-mean-square value of vibration acceleration with the subjective feeling and vehicle vibration comfort, resolves difficult problems about evaluation and comparison of automobile ride comfort brought about by multiple factors, such as different speeds, different measuring points, different roads and characteristics of driver control. But it can not be used for pulse input evaluation and power absorption method because it is based on ISO2631. By intensively analyzing and studying the evaluation method of the vehicle general vibration, drawing on its academic thoughts, based on evaluation indices of different speeds and location, the concept of the vehicle vibration comfort is given up, so a new method of the vehicle ride comfort comprehensive evaluation is put forward by replacing the vehicle vibration comfort with the vehicle ride comfort comprehensive evaluation index. The method applies to not only the evaluation methods based on ISO2631 but also pulse input evaluation and power absorption method. Therefore, the new method of the vehicle ride comfort comprehensive evaluation derives from the vehicle general vibration comfort evaluation method, while also succeeding and developing this method. It is a more common method that can carry out a comprehensive evaluation of the vehicle ride comfort based on all kinds of current evaluation indices.(2) The software development of the vehicle ride comfortThe evaluation system software of the vehicle ride comfort which includes the vehicle ride comfort evaluation of random input and pulse input is developed based on the platform GUI of Matlab in this thesis. The vehicle ride comfort evaluation of random input includes four kinds of evaluation indices, respectively, GB evaluation index which is root-mean-square value of weighted acceleration, power absorption evaluation index, comprehensive evaluation indices based on GB and power absorption method. The vehicle ride comfort evaluation of pulse input includes two types of evaluation indices, respectively, the largest (absolute value) acceleration evaluation index and comprehensive evaluation index based on the largest (absolute value) acceleration. When applying this software, the vehicle ride comfort evaluation can be carried out by simply inputting passage parameters and experimental data files, and then the evaluation results can be obtained. The software has the advantages of simple operation and convenient application.(3) Driving test methods of the car ride comfort for pulse input and random input are drawn up. According to the test results of four typical hatchback cars, the ride comfort of hatchback cars is analyzed by applying the evaluation system software of the vehicle ride comfort.Through the comparative analysis of the vehicle ride comfort evaluation results for four kinds of hatchback cars, it is shown that remarks based on the evaluation indices of traditional evaluation methods are significantly different under different speeds and different measuring points, and it is difficult to obtain an exact evaluation result. But after defining the speed weighted coefficient and the location weighted coefficient of the comprehensive evaluation, comprehensive evaluation indices which combines vibration information of different measuring points under all conditions can come to the only conclusion which can be used to compare multi-models and different types of vehicles. It is difficult for the traditional methods. It is shown that the comprehensive evaluation method mentioned in this thesis is feasible and accurate, and can be used to evaluate and compare the ride comfort of the actual vehicles.