轮胎花纹对整车气动特性影响的等效方法研究

本文基于LBM方法,首先计算了旋转条件下具有详细花纹外形的车轮的气动特性,然后将轮胎花纹简化为纵向沟槽,利用不同表面粗糙度系数值等效详细花纹外形的气动效应,计算旋转条件下的外形简化车轮的瞬态外流场特性。对比分析了两种外形车轮的流场分布特性和气动力发展结果,以及表面粗糙度系数值对气动特性的影响,获得了能够准确反映详细车轮花纹气动效应的表面粗糙度系数值,据此对整车瞬态外流场进行了数值计算,将结果与风洞实验值进行对比,一致性较好并且计算精度较高。该方法确定了较为合理的等效表面粗糙度系数值,对车轮旋转条件下的整车瞬态空气动力特性进行了较为准确的模拟,简化了处理轮胎详细几何的复杂程度,计算效率得到提高。     

重型商用车汽车轮胎花纹对整车性能的影响

汽车轮胎是汽车的行驶系统的重要组成部分,对汽车保持正常的行驶起着重要的作用.除了承载着全车重量,传递驱动转矩外,车轮还还起着减震和缓冲,转向和制动的作用.轮胎对汽车的驾驶性、通过性、舒适性和安全性都有着直接的影响.文中从各轮胎花纹的性能,轮胎性能对整车性能的影响和分轮位配置花纹的优势,为整车提供更经济,安全,可靠的轮胎花纹的匹配方法.     

轮胎胎压对整车性能的影响

轮胎是车辆与地面接触的唯一部件,汽车轮胎气压的高低,将直接影响到整车行驶的舒适性、安全性以及燃油经济性等整车综合性能。在保证整车操纵稳定性、舒适性的同时,适当的提高轮胎胎压,将有利于整车阻力降低,进而降低整车油耗、电耗,以应对工信部越来越收紧的乘用车平均油耗目标。文章通过不同轮胎气压的整车性能实车试验,分析了轮胎气压变化对整车性能的影响。     

胎面花纹对轮胎性能的影响

分析了胎面花纹对轮胎行驶性能、滚阻、磨耗、滑水和噪声特性的影响，介绍了通过胎面花纹设计提高轮胎性能的基本途经和方法。     

载荷和轮胎花纹对汽车通过性能影响的试验研究

为了寻求路面、载荷和轮胎诸因素对汽车通过性能的影响,对装用四种不同配方和花纹轮胎的EQ140型汽车进行了四种路面、两种载荷(空载和满载)的正交试验,并根据测试结果在CF-500型数据处理机上进行了处理和分析,最后得到了载荷和轮胎花纹对汽车的通过性能有显著性影响的结论。     

轮胎磨损及花纹深度测量方法浅析

车辆在行驶过程中,轮胎除了正常的均匀磨损外,还会产生不同程度的异常磨损。轮胎磨损主要有走合期轻微磨损、稳定磨损、剧烈加速磨损3个过程。定期检查轮胎花纹深度并依此及时对轮胎进行保养维护,可以减少不必要的轮胎磨损,降低事故发生率,提高车辆行驶安全性。目前,轮胎花纹磨损检测方法主要有接触式和非接触式2种,都是通过对轮胎各点的花纹深度进行检测,进而得知轮 胎磨损的具体情况。随着科技的发展,将无线传输技术和大数据应用相结合的智能化检测技术应用于轮胎磨损检测,可以将轮胎的监测、报警、预警和反馈等功能进行融合,形成高效的轮胎检测应用体系。     

商用车轮胎花纹对车辆燃油经济性的影响

轮胎作为车辆唯一与地面接触的元件,轮胎状态是整车性能表现关键的一环。轮胎花纹对汽车动力性、操控稳定性、整车舒适性和燃油经济性都存在一定影响。其中,轮胎花纹对燃油经济性的影响主要体现在对轮胎滚阻系数的影响,理清轮胎花纹形式和燃油经济性的关系对整车轮胎选型有着重要的意义。     

整车性能开发过程中的轮胎选型

轮胎是车辆部件中唯一接触地面的部件,整车的经济性、NVH(噪声、振动与声振粗糙度)、操纵稳定性、制动性能等都与轮胎有着密切的关系,选择最优轮胎匹配车型,达到整车各性能的最优化,是整车性能开发的重要组成部分。文中从基准轮胎和基准车型的选择出发,探讨整车开发过程中的轮胎选型及各整车性能间平衡的原则。     

浅析怠速变化对整车的影响

随着汽车技术的发展,越来越多的顾客注重汽车的性能,尤其关注车辆的燃油经济性、NVH以及转向力。并且汽车制造行业是经济发展的重要支柱之一,汽车是人们必不可少的交通工具,只有更加完善车辆的性能,才能满足顾客日益增长的需求。文中依据在不同发动机怠速转速下,通过客观测量与主观评价对比,具体分析了怠速变化对整车燃油经济性、NVH和转向力的影响,寻找提升整车性能的合理方案。     

On the handling performance of a vehicle with different front-to-rear wheel torque distributions

ABSTRACT

The handling characteristic is a classical topic of vehicle dynamics. Usually, vehicle handling is studied by analyzing the understeer coefficient in quasi-steady-state maneuvers. In this paper, experimental tests are performed on an electric vehicle with four independent motors, which is able to reproduce front-wheel-drive, rear-wheel-drive and all-wheel-drive (FWD, RWD and AWD, respectively) architectures. The handling characteristics of each architecture are inferred through classical and new concepts. The study presents a procedure to compute the longitudinal and lateral tire forces, which is based on a first estimate and a subsequent correction of the tire forces that guarantee the equilibrium. A yaw moment analysis is performed to identify the contributions of the longitudinal and lateral forces. The results show a good agreement between the classical and new formulations of the understeer coefficient, and allow to infer a relationship between the understeer coefficient and the yaw moment analysis. The handling characteristics vary with speed and front-to-rear wheel torque distribution. An apparently surprising result arises at low speed: the RWD architecture is the most understeering configuration. This is discussed by analyzing the yaw moment caused by the longitudinal forces of the front tires, which is significant for high values of lateral acceleration and steering angle.     

A study on the effect of different tyre imperfections on steering wheel vibration

Multibody dynamics and tyre models have made possible detailed analysis not only for ride and handling, but also for determining their effects on tyre nonuniformities. The aim of this paper is to analyse the steering wheel vibration, both shimmy and shake, excited by different tyre imperfections by using the commercial simulation package ADAMS/car 2005R2 and FTire. Different settings with respect to imperfection locations, amount, and the combined effects of defects have been studied. An interesting beat phenomenon is observed when all the wheels have imperfections. A procedure to determine the type of imperfections in the tyre from the results of the test rig has also been proposed.     

Research into the problem of wheel tread spalling caused by wheelset longitudinal vibration

This study mainly focuses on the mechanism of wheel tread spalling through wheelset longitudinal vibration that has been often neglected. Analysis of two actual cases of the wheel tread spalling problem leads to the conclusion that the wheel tread spalling is closely related to the wheelset longitudinal vibration in some locomotives, and many of these problems can be reasonably explained if the wheelset longitudinal vibration is considered. For better understanding of some abnormal wheel spalling problems, the formations of the wheelset longitudinal vibration and the wheel/rail contact parameters were analysed in the initial wheel tread spalling. With the preliminary analytical results, the wheelset longitudinal dynamic behaviour, the characteristics of wheel/rail contact and the mechanics in the condition of the wheelset longitudinal vibration were further studied quantitatively. The results showed that the wheelset longitudinal vibration changed not only the limit of these parameters and the position of principal stress, but also the direction of the principal stress on the surface of wheel/rail contact patch. It is likely that the significant stress changes provoke too much stress on the surface of wheel/rail contact patch, cause fatigue in wheel/rail contact patch and eventually lead to wheel tread spalling. The results of these studies suggest that the suppression of the wheelset longitudinal vibration extends wheel/rail life and the addition of a vertical damper with an ahead angle provides a possible solution to the wheel spalling problem.     

Analysis of handling performance based on simplified lateral vehicle dynamics

In this article, the analysis methods for vehicle handling performance are studied. Using simple models, dynamic characteristic parameters such as yaw, natural frequency, and the damping coefficient of a vehicle can be theoretically formulated. Here, the vehicle is simplified by a bicycle (single-track) model, and the tire is modeled by an equivalent cornering stiffness and first order lag. From the experimental road data, the tire model parameters (equivalent cornering stiffness and time lag constant) are extracted. These parameters are then inserted into the theoretically formulated equations of dynamic characteristic parameters. For the purpose of validating the efficiency of the suggested methods, experimental road tests (where the cars have different handling performances) are performed. The results show that vehicle handling performance can be sufficiently represented by the suggested dynamic characteristic parameters. So, it is concluded that the proposed method has practical use for the development of new cars or for the comparison of similar cars since the evaluations of the vehicle handling performance can be efficiently determined by the suggested dynamic characteristic parameters.     

添加剂对汽车性能的影响

汽车使用的添加剂有燃油添加剂、润滑油添加剂、冷却液添加剂等。它的质量以及使用水平对汽车使用性能会产生哪些影响，应如何选择呢？     

Multi-axle vehicle dynamics stability control algorithm with all independent drive wheel

The stability driving characteristic and the tire wear of 8-axle vehicle with 16-independent driving wheels are discussed in this paper. The lateral stability of 8-axle vehicle can be improved by the direct yaw moment which is generated by the 16 independent driving wheels. The hierarchical controller is designed to determine the required yaw torque and driving force of each wheel. The upper level controller uses feed-forward and feed-backward control theory to obtain the required yaw torque. The fuzzification weight ratio of two control objective is built in the upper level controller to regulate the vehicle yaw and lateral motions. The rule-based yaw moment distribution strategy and the driving force adjustment based on the safety of vehicle are proposed in the lower level controller. The influence of rear steering angle is considered in the distribution of driving force of the wheel. Simulation results of a vehicle double lane change show the stability of 8-axle vehicle under the proposed control algorithm. The wear rate of tire is calculated by the interaction force between the tire and ground. The wear of tire is different from each other for the vehicle with the stability controller or not.     

不同车速下路基动态测试分析

在116km／h内,对不同车速下路基的动应力与加速度进行了测试,分析了路基动应力与列车速度的关系以及路基振动频率结构和振幅范围。为既有线路路基在提速状态下的评估技术和标准提供了依据,也为既有线路在提速状态下路基病害的预防和整治提供了依据。     

添加剂对汔车性能的影响

汽车使用的添加剂有燃油添加剂、润滑油添加剂、冷却液添加剂等.它的质量以及使用水平对汽车使用性能会产生哪些影响,应如何选择呢?