四轮定位仪诊断故障实例

四轮定位仪主要用于检测车轮定位参数如前轮前束，前轮外倾角、主销内倾角，主销后倾角。后轮前束，后轮外倾角，包容角，转向前展角，后轮推进角，前轮定位参数的变化常与转向系和行驶系零部件的状态有关。所以．通过检测这些参数可以诊断转向系和行驶系的故障。下面举例说明。     

四轮定位仪的评述（一）

车轮定位通常是指汽车转向轮定位。由于大多数汽车采用前轮转向，因此，车轮定位又称前轮定位。前轮定位参数包括主销后倾角、主销内倾角、前轮外倾角和前轮前束。它们的共同作用是：使汽车保持直线行驶的稳定性；使转向操纵轻便；使转向轮每一瞬间接近正前方滚动而无滑动，以减轻轮胎磨损等。     

浅谈汽车前轮定位的作用

本文主要对汽车主销后倾角，内倾角，前轮外倾角，前轮前束等汽车前轮定位的作用做了简要论述。     

现代汽车前轮定位角的新变化

前轮定位角包括主销后倾角、主销内倾角、前轮外倾角及前轮前束。前轮定位角的作用是保持汽车直线行驶的稳定性、转向操纵轻便性和稳定性,减少轮胎和机件的磨损等。现代汽车的高速化、前轮驱动化、超低压子午线偏平胎的使用、双制动管路交叉排列及汽车急起步、急加速、急制动、急转向工况的出现,使前轮定位参数发生了新的变化。     

现代轿车车轮定位的新变化

汽车在正常行驶过程中，应具有转向操纵轻便和自动保持直线行驶的能力。同时转向轮应尽可能保持纯滚动，以减轻轮胎的磨损。为了满足上述要求，通常是通过主销后倾角、主销内倾角、前轮外倾角和前轮前束等转向轮定位的4个参数来保证的。随着汽车技术的迅速发展，现代汽车特别是轿车普遍出现了高速化趋势，     

建立“四轮定位的新理念”

<正>在传统结构的汽车上,转向轮、转向节、转向桥三者之间的相关几何角度位置称"前轮定位"。它包括主销后倾角、主销内倾角、前轮外倾角、前轮前束等四个内容,而后轮无定位角度内容。其目的是保证汽车稳定直行、转向轻便、减小轮胎的磨损和行驶的安全性。这种传统的理念,流传了几十年。随着高速公路的出现,汽车已进入高速化、电控化、高档化的技术领域,先进的结     

汽车前束的合理调整

为了保持汽车直线行驶的稳定性和转向的轻便性,并减少轮胎与机件的磨损,转向车轮、转向节和前轴三者与车架的安装是有一定相对位置的.这种具有一定相对位置的安装称为转向轮定位,也叫前轮定位,它包括主销后倾、主销内倾、前轮外倾及前轮前束4个内容.     

主销后倾角、主销内倾角与转向自动回正

一、前言 在汽车转向后，只要停止转向（放松方向盘），汽车就有一个自动回位的趋势，这种趋势与前轮定位角中的主销后倾角及主销内倾角也有关系。本文就这两个角度与转向回正之间的关系进行探讨。     

详解四轮定位

车辆行驶中出现行驶跑偏、稳定性差、轮胎偏磨或发出尖锐的声音等情况时，使用四轮定位仪对问题车辆进行测量，就会发现车辆主销后倾角、前束、主销内倾角、前轮外倾角等数值都已经改变，只是数值的偏差有时凭肉眼无法判断。其实这些偏差角度，决定了车辆的转向和行驶性能。     

客车主销定位角和回正力矩的计算及关系

推导出车辆主销定位参数引起的回正力矩计算公式;分析主销定位参数的作用;提出直线行驶的车辆,虽然没有侧向力的作用,但其左右转向轮仍有预加的回正力矩,以及回正力矩与主销偏移距没有关系的结论。     

轮胎动态侧偏特性对汽车摆振的影响

轮胎的侧偏力学特性是影响汽车前轮摆振的最关键因素之一，文中在箕是汽车研究所提出了轮胎动态侧偏特性试验方法的基础上，建立了侧向力与回正力矩的精确表达式，并从能量反馈和负阻尼效应研究了轮胎动态侧偏特性参数对汽车偏摆振的影响。     

全电动轮汽车的转矩协调控制策略研究

本文从降低最大轮胎利用率、提高车辆附着稳定性的角度,在基于载荷的转矩协调策略的基础上,提出了基于名义载荷的转矩协调策略。对该策略在所建立的非线性七自由度车辆动力学模型中进行了前轮角阶跃输入工况下的仿真分析,效果较好。该策略对于全电动轮汽车转矩协调策略的研究具有一定的参考意义。     

The Wheel Shimmy Problem: Its Relationship to Wheel and Road Irregularities

The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability.     

轮胎非稳态转向特性非线性仿真模型

本文以轮与路面之间的滑移速度为出发点，在稳态指数统一模型的基础上，建立了轮胎非稳态转向特性非线性仿真模型。在实验研究中，发现了动态过程回正力臂和附加的回正力矩的滞后特性。仿真和试验结果对比表明，该模型足以反映轮胎非线性转向特性，可用于前轮及汽车操纵动力学仿真方面的研究。     

The Wheel Shimmy Problem: Its Relationship to Wheel and Road Irregularities

SUMMARY

The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability.     

电动助力转向系统的回正与主动阻尼控制策略研究

针对配备电动助力转向系统的车辆低速时回正性差,而中高速时又容易出现回正超调的现象,提出了一种新型的回正与主动阻尼控制策略。该控制策略以功能原理为理论基础,可以随车速和转向盘转角的不同而调整回正力矩或阻尼力矩的大小。实车试验的结果证明,该控制策略能够改善车辆低速时的回正性,抑制车辆中高速时的回正超调现象,并且在施加了回正与主动阻尼控制后,驾驶员的操纵手感没有受到不良的影响。     

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.     

Resistance torque control for steer-by-wire system to improve human–machine interface

A steer-by-wire system, which has no mechanical constraints between steering wheel and front wheel, is expected to improve steering performance. The mechanical resistance torque is not transmitted from the front wheel to the steering wheel, and it is essential to simulate the torque around the steering wheel for better human-machine interface. Previous studies investigated resistance torque control originating from vehicle behaviour variables such as yaw rate and lateral acceleration. However, other variables such as steering wheel angle and front wheel actuation force are also good candidate sources to generate resistance torque. In this paper, first, four general guidelines are introduced to evaluate three types of resistance torques, i.e., the steering wheel angle origin, the steering force origin and the vehicle behaviour origin. First two guidelines are for ‘driver-made’ phase to make a turn, while the third guideline is for ‘vehicle-made’ phase to return to straight driving and the fourth one is the applicability guideline. Satisfaction of these guidelines by each of the three resistance torques is examined by the actual vehicle experiment. A necessity of combining these three types of resistance torques is indicated as a future subject.     

轮胎动力学特性仿真分析研究

分析了各种常用轮胎模型的特点与应用范围,根据汽车操纵动力学研究的需求,在Matlab环境下运用魔术公式建立了轮胎动力学模型,并对汽车轮胎力与纵向滑移率,纵向力、侧向力及回正力矩与纵向滑移率、侧偏角、外倾角、垂直载荷的关系等轮胎特性进行了仿真分析,实验结果表明,魔术公式轮胎动力学模型可以较好地模拟轮胎的动力学特性,适用于车辆动力学研究领域。     

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.