机械毕业设计英文外文翻译468四轮转向汽车的转向特性及控制技术
附录附录ASteering Behavior and Control Technology0f Four—wheel Steering AutomobiIeABSTRACTThis paper analyses the characteristics of car four-wheel steering control to, summarizes the principle of construction four-wheel steering cars. Introduced the four-wheel steering system control strategy. Points out the four-wheel steering system control technology faces difficulties, and prospects the trend of its development.Keywords: four-wheel steering; Steering characteristics; Working principle; Control; Development;1. IntroductionWith modern road traffic system and the development of modern automobile technology, people on the car's steering control performance and driving stability requirement is increasing day by day. As the most effective improve vehicle handling performance of a kind of active chassis control technology - four-wheel steering technology. In the 1980s began in cars get application, and as the modern automobile industry and continuous development. Car four-wheel steering means in turn, the rear car can be relative to body active steering, that the car can be up to four wheels role. To improve the car turned to maneuverability, handling stability and driving safety.2. The car's steering four-wheel steering2.1 4ws cars and 2ws steering process analysisOrdinary two wheel steering can not only the front car around its own wheel rotation and relative to body deflection around the precision, then wheel rotation and not only deflection. When the driver turned the steering wheel, front wheel steering, changed directions face front tyre, produced a transverse force, through the front wheel effect on body, make the body yawing and produce centrifugal force, the rear wheels cornering,produced change direction, participate in the sports car to. And the rear and front car 4ws as, can rotation can also deflection. When the driver turned the steering wheel, front and rear wheels, that car almost at the same time to change direction, realize steering movement.In turn, the 2ws car before active steering wheel rotation just makes passive steering. Obviously, 2ws cars in steering process from the steering wheel rotation to rear wheel steering movement in between the existence of certain lag time. This phase lag 2ws automobile steering characteristics make the servo sex becomes poor, and that the car steering radius increased. In addition, 2ws car at a high speed, the steering wheel Angle relative to certain incremental, body yaw-rate and lateral acceleration incremental increases, made the car at a high speed handling and stability becomes poor. And in turn, the car 4ws has done before, rear wheel steering, active in the process of steering, high sensitivity, fast response, effectively overcome the shortcomings.2.2 4ws automobile steering wayAccording to the theory analysis and road test showed that a four-wheel steering can improve the maneuverability and steering control stability of high speed, modern 4ws car is developed according to the guiding ideology. Generally speaking, in the process of steering cars in 4ws, according to different driving conditions, front and rear wheel steering Angle should follow certain rules between. At present, the front, rear typical 4ws deflection rules generally are described below:(a) inverse phase steeringAs shown in figure A1 (a) shows, steering wheel Angle at low speeds or larger, front and rear inverse phase shift, realize that the rear wheels with the front deflect deflect instead, and with the steering wheel Angle deflection Angle increases and increases in a certain range. This redirection speed way can improve the manipulation of the car, reduce automobile portability turning radius, making cars maneuverability. Easy car turned turn, obstacle avoidance and driving, garage and parking. As for cars, if rear inverse phase 5 °, then turned can reduce minimum steering radius was about 0.5.(b) phase with steeringAs shown in figure A1 (b) shows, in a high-speed or steering wheel Angle is lesser, front and rear wheels with phase shift, realize that the rear wheels deflect the deflection direction with front wheel. Make the car body yaw-rate greatly reduce automobile body, can reduce the tendency of cornering undergo dynamic, guarantee the overtaking the highway, elevated highway, in and out, in the approach and flyovers insufficient steering state. Now, there are many 4ws cars take improving vehicle handling performance focuses on making cars on high-speed steering stability, without excessive demands in low-speed driving car course-altering maneuvers flexibility. The features is low by front wheel steering car only when only in car speeds, after up to a certain value, rear, only participate in steering phasewith four-wheel steering.（a）Reverse a steering （b）Coincidental a steeringFigure A1 four-wheel steering the front of the car, rear deflection rule3. Four-wheel steering car components and working characteristics4ws car is in front wheel steering system, and on the basis of suspension in cars on install a set of rear wheel steering system, both through certain questions of contact, making cars in front wheel steering also participate in the meanwhile, rear wheel steering. After decades of research and development, have molding 4ws car type has a variety of, composition, structure is different, working principle and control methods vary. The typical electric 4ws system mainly by the front wheel steering system, sensors, ECU, rear wheel steering actuators and rear wheel steering transmission mechanism etc. the sensor will front wheel steering motor sports the signal and the signal into ECU were analyzed and calculated, will process after the drive signal to rear wheel steering actuators, rear wheel steering actuators action, through the rear wheel steering transmission mechanism, rear wheel deflection. Meanwhile, ECU when carried out monitoring car operation condition, calculate target steering Angle and rear real-time steering Angle, the difference in value between real-time adjustment to rear wheels corner. Such, can according to the actual sports car, to realize the state car four-wheel steering. General 4ws cars equipped with two turning mode, can enter 4ws state, also can keep the traditional 2ws state, drivers can pass the driving indoor steering mode switch selection. When 4ws car in the course of driving the electronic control system malfunction, rear wheel automatic back into the middle, the automatic into the front wheel steering state, ensure like ordinary front wheel steering car driving safely as automobiles. Meanwhile, dashboard "4ws" indicator, warning drivers, stored on ECU fault condition of warranty, so that by yards.4. Four-wheel steering control of the car4ws system not only to realize the need for automotive steering movement, and guarantee the vehicle steering traveling stability. At present, in the research and development of automobile 4ws centered on improving car, the transient manipulation stability as a starting point, explore due to rear brought car in response to changes, andadopts various rear wheel control strategy and produce different effect. Auto four-wheel steering control depends on tires were lateral force, four-wheel steering can make cars in turn, the rear directly involved in for car yawing movement and lateralizing control. Through timely, accurate control of the rear wheel steering Angle, not only can shorten the process of steering the transient response, and can actively control cars the trajectory and attitude. In turn, that the car during its longitudinal direction centerline of the direction, even with the direction of the car horn decreases overlap, attitude Angle of steering bodywork cornering, improves the lateral stability car.4.1 control goalsThat car in turn to basic keep PianJiao zero gravity side car. So can greatly improve the car to the steering wheel input dynamic response characteristics, largely improved yaw-rate and lateral acceleration of transient performance indicators, lower the body posture change. From the PianJiao zero target start. According to certain control program is to realize the rear wheels to function is derived based four-wheel steering. Of course, the modern 4ws cars also have some other control goal request.4.2 control strategy model basedThe general situation of the studies are 4ws system based on a simple dof vehicle model of linear. This is just a kind of utopian mathematical model, when modeling overlooked in some of the dynamic parameters of the car without considering changes, automobile driving produces in the process of many of the random uncertainties and not very accurate. Early 4ws controller design are based on linear dynamic equation with the hypothesis, but due to the above reasons, make the design of control system doesn't meet practical needs, there is no guarantee that the vehicle steering control stability.4.3 control methodDifferent cars driving performance requirements of steering and different models of the car wheels deflection 4ws law is not the same. Thus, different 4ws vehicle USES control method is endless and same, various control method has its emphases respectively. At present, in some molding 4ws with car on the control method basically has:(a). The set than simply steering system 4ws.(b). Than before, rear wheel steering front-wheel corner function 4ws system.(c).Than before, rear wheel steering j speed function 4ws system is.(d). The 4ws with first-order lagging system.(e).With reversed-phase characteristics 4ws system(f). With optimal control characteristics of 4ws system.(g). Has since learning, white the ability to adjust the 4ws system.Former five kinds of control system belong to classical control theory category, only to satisfy car under certain conditions, but also can't adapt to the need of motor sports ofrandom changes, along with the computer technology and some advanced control theory of development, 4ws system will towards adaptive, intelligent direction.4.4 4ws system control technology developmentAt present, for research and development of car 4ws remains constant developing and perfecting stage. Although researchers from structure to control principle of four-wheel steering on have done a lot of research, 4ws technology have made many progress. But, in the use of modern control theory of automotive steering control strategy choice of methods of determination and control, mainly depend on experience, the corresponding theoretical basis is still very lack, 4ws technology not really into wide use in commercial car on stage, no widely used.In the technology in relatively mature 4ws cars, most use electric hydraulic power 4ws system. With the rapid development of electronic technology, computer technology in cars, the wide application of electronic electric 4ws system will be the trend of the development of automobile 4ws. Although in 4ws system research and development has made great development, however, as the core technical problems 4ws system - 4ws system controller design, what on earth as the best control objectives? Adopt what kind of control method? Still no in this field is the same view. Already, early before of the 4ws and the system based on a simple dof vehicle model, linear controller design are based on 4ws with linear dynamic equation hypothesis, PID control strategy. We know, 4ws system control mainly dependent on tires were transverse force. Early studies is the automobile tires as linear model, general 4ws control is based on the transverse force by tire wheel in proportion to the side PianJiao assumptions, this assumption just in the lateral acceleration smaller range effective. When in the lateral acceleration larger range, tire cornering characteristics of nonlinear area, will go to one side of the PianJiao tyres by transverse force in the response of the relationship of scale, and no longer the longitudinal force by tire vertical load, etc, have relations. In fact, car in turning down the street, tire basically all work in nonlinear area. At this time, garnish with linear control theory for research, appear reluctant to. 4ws vehicle handling dynamics problems is very complicated nonlinear multibody dynamics problems of the control system for 4ws research should be taken into account in the sports car, in-depth study of affecting its state response, establish simulation kinetic parameters of actual sports car mathematical model, adopt more effective control strategy. With the continuous development of control technology, some advanced modern control method has been applied in 4ws system control study, as optimal control and adaptive control, sliding mode control, robust control etc, in recent years, appeared again fuzzy control, based on artificial neural network theory, control method, etc. The study of 4ws control system from linear field gradually transition to nonlinear fields, some multi-degree-of-freedom car dynamics models have proposed 4ws, but mostly in infancy, is not mature. The future of thedevelopment of the system is studied 4ws trend for mainly concentrated :(a). Further research and development of new rear wheel steering actuators and rear wheel steering transmission mechanism, improve the manipulation of steering portability, flexibility and steering Angle of accuracy.(b). For 4ws system, further development, design high performance, high precision, high sensitivity sensor, in order to correctly detection car sports signal.(c). Deep study turning the tyre during transient characteristics as the main factors, to join in the mathematic model of the system 4ws.(d). The control theory and control into method is applied to the 4ws controller study.附录B四轮转向汽车的转向特性及控制技术摘要本文分析比较了四轮转向汽车的转向特点，概述了电控四轮转向汽车的结构原理。
毕业设计---汽车转向机构英文翻译资料
Automobile Transmissions and Power Steering Automobiles, trucks, buses, and tractors all depend on transmissions to deliver power from the engine to the wheels, The gasoline and diesel engines that power these vehicles cannot be connected directly to the wheels, because the engines must keep turning at a certain seed to keepfrom stalling. Also, different amount of torque (turning force) must be delivered to the wheels atdifferent times. A large amount of force is needed to get a car moving from a standstill. Less force is needed to keep the car moving once it is rolling. Going up a hill of driving at high speed requires still other amount of force. It is the job of the transmission to deliver the particularamount of force that is needed. The transmission also allows a motor vehicle to back up-----gasoline and diesel engines can run in only one direction, but the transmission can reverse thedirection of the force. And when a car stops, the transmission lets the engine keep running without moving the wheels.The heart of any transmission——even an automatic one—is a set of gears. Gears do notchange the power of an engine, but they can increase the torque by decreasing the speed. They canalso increase the speed by decreasing the torque.The automobile transmission uses a series of gears which enables the engine to continue tovehicle’’s speed is altered. Setting an automobile in operate at maximum efficiency when the vehiclevehicle’’s weight. This motion requires a large amount of power to overcome the inertia of the vehicleprocess requires high engine speed, needed for high power, and a gradual increase in a vehicle’sspeed to avoid a jerky start. To do this, a low gear ratio is allows the crankshaft to revolve several times in order to turn the real axle once. The low gear ratio is used for starting, climbing steep slops, and other situations in which maximum power is required .As power needs are reduced, a second, higher gear ratio is used which rotates the rear axle with fewer revolutions of the crankshaft. As the car’s speed increases, successively higher gear ratios are used until the drive from the engine to the rear wheels passes through the transmission without reduction. Two principle types of transmission are used, manual and automatic.The manual transmission system permits the driver to select the desired gear ratio bymanipulating a shift lever. Besides the forward speed gears, additional gearing is incorporated topermit the vehicle to operate in reverse. Manually operated passenger car transmission used in the United States and Canada usually have there speeds forward and one in reverse. Trucks, tractors, buses, and other heavy-duty vehicles have as many as 10 forward speeds and 2 in reverse. These units are basically five-speed transmissions with a two-speed auxiliary gearbox. Transmission that are to be shifted with the vehicle in motion incorporate synchromesh units to prevent gears from clashing as they are meshed. The synchromesh unit synchronizes the speed of the gears so that they revolve at the same speed as they slide into engagement.The automatic transmission system changes gear ratios automatically in response to changesin engine speed or throttle setting. The use of automatic transmissions increased tremendouslyafter World War Ⅱ, and they are installed in more than half of the automobile produced in the United States. Automobiles equipped with an automatic transmission have a control lever which allows the driver to select neutral, low, drive, and reverse. The engine is started in neutral, and the lever is moved to “drivedrive”” position the drive”” for normal operation when moving forward. In “drivevehicles can accelerate from rest to maximum speed by simply depressing the accelerator. Thelow”” position prevent the transmission from shifting out of the lower gear ratios.“lowIt is used for climbing steep grades, in mud, or at other tomes when maximum power ispark”” position, which locks the transmission to prevent a parked car needed. Some units have a “parkfrom rolling. The automatic transmission makes it easier to drive a car, but it is less efficient than a manually shifted unit and increase gasoline consumption. For this reason, the automatic transmission is not as common in Europe, where economy of operation is a prime sales factor.Four basic types of automatic transmissions have been developed to the point where they have been installed in production vehicles. The first consists of a standard mechanical transmission and clutch which is automatically shifted by pneumatic, hydraulic or electric power units. The second type uses a hydraulic torque converter plus a planetary gear system to increase engine torque. The third system combines a hydraulic coupling with an automatically shifted mechanical gearbox to provide torque amplification. The fourth type uses one or more stages of hydraulic torque conversion to provide torque multiplication.Automatic transmission shift in response to signals from speed sensing and throttle position sensors. The units incorporating hydraulic torque converters use the hydraulic fluid, under pressure, to engage and disengage planetary gear trains.Power steering system 也是汽车重要的一部分，The car of today is larger and heavier than earlier cars; the tyres are wider, further apart and inflated to lower pressures .In addition, the trend of development has been to place more than half the weight on the front wheels, especially the weight of the engine , which itself is larger and heavier than in the early days.To make cars easier to steer, the gear ratio in the steering box at the end of the steering column was changed to that turning the wheel required less torque, but this increased the number of turns of the steering wheel required on modern cars without power steering compared to 2.5 or 3 turns for cars built before 1940. Modern cars with power steering only require about three turns.Power assisted steering was first developed in the 1920s; one of the first devices was developed by an engineer at Pierce Arrow, an American make of luxury cars. The Cadillac division of General Motors was going to offer power steering as optional equipment on some models in the early 1930s, but the depression interfered with development. During World War Ⅱ power steering was fitted to military vehicles; in 1952 Chrysler began offering it , and it is now standard equipment on many of the biggest American cars .Electric devices were tried , but power steering today is always hydraulic , with oil pressure of perhaps 1000 psi (70kg/cm2) maintained by a pump driven by the engineer of the car . The system is a servomechanism, or servo loop, which makes a correction to compensate for the torque applied to the steering wheel by the driver. It consists of an actuator and a control valve. The actuator is a hydraulic cylinder with a piston, or ram, which is free to travel in either direction from the center. The function of the control valve is to respond to the torque from the steering wheel by actuating smaller valves at each end of the cylinder. The system is designed to assist the steering linkage, rather than to replace it, and it does not do all of the work of steering , but leaves some of it for the driver. Thus if the hydraulics fail the car can still be steered , though with greater effort, and at all times the feel of the road is mechanically transmitted from the front wheels to the hands of the hands of the driver on the steering wheel, an essential element of safe driving. The power steering makes a positive contribution to safe driving in that if the driver hits a small obstacle in the road or has a flat tyre at speed, the power unit makes it easier to keep the car under control. Many large cars fitted with wide, stiff radial ply tyres would be nearly impossible to steerat parking speeds without power steering.Hydrostatic systems, designed for off-the-road vehicles, are exception to some of this, because they dispense with the steering column and the steering box , and the steering wheel and the steered wheels are connected only by hydraulic tubes or hoses.The power steering system includes a reservoir to hold the oil. Oil pressure is always provided when the engine is running, but when the system is at rest, that is when the steering wheel is not being turned, equal pressure is available to each side of the piston in the actuator, so that it does not move.There are basically two types of power steering system: those which have the control valve located within the steering box, in which case it is usually a rotary valve, and those in which the valve is integral with actuator, when it is an axial spool valve.汽车传动系与动力转向装置轿车、卡车、公交车以及拖拉机都靠汽车传动系将动力从发动机输送到车轮上。
机械类汽车转向系统外文文献及翻译
1 IntroductionThe key task for the automobile industry and its suppliers in future lies in speedily developing and implementing ecologically sound and economically justifiable mobility systems. Light metals such as aluminum and magnesium along with glass and carbon fiber reinforced materials, ceramics and composites have opened up the potential for considerable weight reduction and for "green" vehicle concepts which can be realized economically. Aluminum in particular can provide the impetus for new designs for the next millennium. Decades ago, the use of aluminum in auto construction was seen as an "experiment"; Today it is a vital factor in reducing weight and thus lowering fuel consumption.The average passenger car today contains 60 to 70 kg of aluminum, and current developments point to a doubling of this amount in the next few years. Motor vehicles both now and in future must meet requirements for: greater performance, greater safety, comfort, low pollution. Lightweight construction is not just about reducing weight; it is a question of -striking the right balance between reduced weight and structural efficiency. In vehicle construction this normally means making the best use of the generally very tight space available for individual components so as to allow weight to be minimized while still meeting all stiffness, strength, natural frequency or acoustical requirements. To achieve this, stresses must be distributed throughout the structure as evenly as possible. Modern numerical analysis methods such as FEA allow a very detailed analysis of system behavior, provide cost-efficient support for the complex process of optimization and thus make a huge contribution to advances in lightweight construction. Packaging, safety considerations, reproducibility and price place restrictions on the degree of weight reduction achievable.The broad range of expertise available to Krupp Presta AG allows the company to analyze customer specifications for steering systems and provide appropriate solutions.2 Requirements to be met by steering systemsThe steering is an important part of the feel of a car. The steering system should make driving an enjoyable experience with no unpleasant vibration from the road surface while guaranteeing the required hand- sing. It is also important that high safety requirements be met, both under normal conditions and in crash situations. The key criteria for the steering system are thus as follows:rolling friction, torsional stiffness /strength, Damping, temperature, corrosion, durability / fatigue, weight. Crash kinematics and energy absorption steering column requirements:natural frequency / stiffness, mass, damping, space, strength (crash, misuse), ergonomics, handling, acoustics, crash kinematics and energy absorption. Other basic conditions:interfaces with adjacent components, installation, joining techniques, price.3 Materialsmaterial light weighting can be achieved by using either stronger or lighter material. When stiffness or natural frequency are Important sizing criteria, low density materials with a high modulus of elasticity by quired. Non-exotic materials must be selected which are readily recyclable, low in price and display good durability.Further requirements are set by the manufacturing and joining processes. Steel, aluminum, magnesium and a variety of plastics are the materials of choice for steering systems.Low specific gravity, high corrosion resistance, low fabricating costs, high energy absorption and good recycle ability make aluminum a favored light weighting material. Owing to its high energy content, up to 90% of the aluminum used in auto construction can be recycled (intelligent design / no mixing with other materials). The favorable energy balance of aluminum puts it at a great advantage over many other materials.In environmental terms aluminum scores highly. The large amounts of primary energy required to make raw aluminum are offset over the lifetime of the vehicle. Composites could also become a very attractive proposition on account of their extreme stiffness, low weight and energy absorption capabilities. At present, howler, price is a problem, as are joining and quality assurance.4 Reducing component weightA focused strategy to reduce component weight requires a lightweight approach to design (force distribution, stresses), material (material selection), specifications (modified, realistic specifications)Key factors in lightweight design include [1]: force flows, material properties, ambient conditions ® safety requirements, reliability of joints, manufacture ability. Practical experience has shown that car makers' specifications based on steel need to be revised for lightweighting. Requirements valid for a steel steering shaft, for example, can result in severe oversizing of an aluminum shaft. Reducing component weight requires material compatible designs combined with material- compatible specifications.5 Lightweight componentsAs part of its development program Krupp Presta is replacing conventional steel steering components such as steering rods , shafts or forks with corresponding aluminum components produced by new processes. Weight savings of 20-30% are achievable depending on the basic conditions stipulated by the customer. Aluminum and magnesium die castings are already being used in steering columns , and further opportunities for weight reduction are being investigated. The lightweight steering column (Fig. 1) produced by Krupp Presta for the Audi A6 is a good example. By using magnesium die castings it has been possible to limit the weight of the steering column to just 5kg, a reduction of 15-20% over conventional (steel) designs.6 Steering column designExperience has shown that it is possible to design steering columns for cars more or less on the basis of their natural frequency alone. Additional engineering work may be required to design critical parts which must not break in the case of a crash or misuse (e.g. theft). The main task when engineering a steering column is thus to achieve the highest possible natural frequencies while minimizing weight. Low-stiffness components are being analyzed and refined in an effort to achieve uniform loading of the structure. In solving this task, use is made of numerical methods such as FEA. The structure is divided into finite elements which are characterized by specific deformation assumptions. Using FE analysis it is possible to examine complex structures, analyze sensitivities and links, discuss variations or ways of making improvements and optimize the structure numerically. Topological optimization is carried out for the analysis of low-stress areas and for the basic design of ribs and beads. CAD geometrydata are processed in an FE pre-processor. Correct modeling of the following is essential, individual parts, stiffness, contact faces, kinematics mass. Modeling is followed by computation and evaluation of the data obtained. The deformation energy is a global measure for assessing stresses. Normalizing the element deformation energy by the element mass provides information on the stresses acting on the element relative to its mass. The kinetic energy is regarded as the influence of vibrating masses which have a negative effect on the natural frequency of the steering column. By evaluating stress and strain conditions, highly localized weak points or high-stress areas can be identified.7 ConclusionsExisting technologies must be continuously adapted and improved in line with the requirements of the auto industry. Systematic weight reduction is a major challenge and requires close cooperation between vehicle manufacturers and suppliers. Materials, fabricating and joining technologies must be further refined. One prerequisite for the continuing success of Krupp Presta is the flexibility to react to customer wishes and requirements.Reference[1] Klein, B.:Leichtbau-Konstruktion. Berech- nungsgrundlagen und Gestaltung.Braunschweig: Vieweg, 1997一、简介汽车工业及其供应商，在未来的关键任务在于迅速制定和实施无害生态和经济上合理流动系统。
【机械类文献翻译】关于非线性整合控制的四轮转向装置和四轮扭矩车辆处理技术的发展
关于非线性整合控制的四轮转向装置和四轮扭矩车辆处理技术的发展Shinichiro Horiuchi!, Kazuyuki Okada!, Shinya Nohtomi"谢新译摘要：这篇文章介绍的是一个四轮转向装置和四轮扭矩的整体非线性控制系统。
这种持续的非线性预示的系统被应用于控制系统的设计。
这种四轮转向装置和每个轮子的扭矩协调的优点通过计算机模拟显示出来。
被带入到模拟中的驾驶力学叙述也被实施。
模拟的结果表示在被提议的非线性控制系统中那个车辆可操作性和安全性在条件受限制的情况下得到显著改良!1999年版权归日本公司和 Elsevier科学B.V.的汽车工程协会所有。
1.介绍在车辆设计中,底盘控制系统有向复杂转变的趋势。
底盘控制系统的三个主要部分是:侧部控制,垂直控制和纵观控制.这些系统是独立发展的去改善操纵,乘坐舒适性和附着摩擦/最好刹车性能来减轻驾驶的工作量。
在他们之中,有效的四轮转向装置系统的提高符合车辆转向能力及前后轮转向装置的相关法规。
这样的转向装置控制系统,通过车辆动力学的线模型描述,使得改善侧面的稳定和操纵性能变成可能[1]。
然而,当轮带接近附着力和侧面受力的非线性特性的极限的时候,四轮转向系统变的不怎么有效。
另一方面，在一个近的界限范围中,刹车和附着摩擦控制系统是有效的[2]。
由于4轮转向系统和轮子转力矩控制系统的适当协调,即使当道路情况是不怎么样的时候,车辆操作的巨大进步也可以实现[3]。
在4 WS 和direct yaw moment control(DYC)已经考虑到了。
在这一项研究中,线性4WS控制器,一个独立设计的DYC 控制器已被使用。
[4]线性模型相配理论和 LQ 控制理论被应用到整合控制系统的设计中。
Yu和Moskwa[5]计划了一个整合的控制系统,这个理论是从使用回应线性化技术和滑模态控制理论中来的。
回应线性化方式在控制浸透之前的控制决定方面遇到困难,回应线性化在一个如此情形中不容易成功。
四轮转向汽车转向特性的研究
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哈尔滨工业大学工学硕士学位论文
第 １ 绪论 章
１ ． １课题研究的目的和意义
随着汽车工业的发展， 汽车的操纵稳定性日 益受到关注，四轮转向 汽车也 得到了广泛的研究。低速时，前后轮进行逆相位转向，减小了转弯半径，提高 了汽车的机动灵活性；高速时，前后轮进行同 相位转向，使汽车由于行驶方向 改变而产生的横摆角速度和侧向加速度很快达到稳态响应，改善了高速时汽车 的操纵稳定性。实践证明，４ 能在很大程度上改善汽车的操纵稳定性。 ＷＳ 四轮转向 技术是改善汽车操纵稳定性的 主要手段之一Ｏ 也是实现主动安 ｌ ， 全性的方法之一。对其的控制策略仍然是在高速时，改善横摆角速度和侧向加 速度的瞬态性能指标；低速行驶时，减小汽车的转弯半径，使汽车在低速行驶
哈尔滨工业大学工学硕士学位论文
浅析四轮转向系统在工程机械中的应用中英文
浅析四轮转向系统在工程机械中的应用中英文Four wheel steering system is analysed in the application of engineering machinery工程机械广泛地被应用到设计生产建设的各个方面。
工程机械通常机身较长，转向不灵活，转弯半径大，与之相矛盾的是，工程机械的作业场地通常都狭窄，工作条件差，障碍物多，行驶路面凹凸不平，而且工程机械要求频繁转向。
这就提出一个迫切的任务，即如何减小工程机械的转弯半径，增加工程机械作业行走的稳定性和可靠性，即我们需要一种转向性能良好的工程机械转向系统。
Engineering machinery is widely applied to design every aspect of production and construction. Engineering machinery is longer than the fuselage, usually not flexible steering, the turning radius is big, and paradoxically, engineering machinery operation site is usually small, poor working conditions, obstacles, more road uneven, but also frequently turned to mechanical engineering requirements. It puts forward an urgent task that how to reduce engineering machinery turning radius, increase walking engineering machinery operation stability and reliability, namely, we need a kind of engineering machinery to the good performance of steering system.四轮转向系统是这些年来得到发展和应用的一种转向系统，从目前现状看来，进口的工程机械采用四轮转向技术屡见不鲜，可是国内对这一技术的研究几乎还处于空白。
四轮转向汽车的转向特性及控制技术-Read
四轮转向汽车的转向特性及控制技术东南大学机械工程系汪东明摘要：本文分析比较了四轮转向汽车的转向特点，概述了电控四轮转向汽车的结构原理，介绍了四轮转向系统的控制策略，指出了四轮转向系统控制技术所面临的困难，并展望其发展趋势。
关键词：四轮转向；转向特点；工作原理；控制；发展。
１、引言随着现代道路交通系统和现代汽车技术的发展，人们对汽车的转向操纵性能和行驶稳定性的要求日益提高。
作为改善汽车操纵性能最有效的一种主动底盘控制技术——四轮转向技术，于二十世纪80年代中期开始在汽车上得到应用，并伴随着现代汽车工业的发展而不断发展。
汽车的四轮转向（Four-wheel Steering ——4WS）是指汽车在转向时，后轮可相对于车身主动转向，使汽车的四个车轮都能起转向作用。
以改善汽车的转向机动性、操纵稳定性和行驶安全性。
２、四轮转向汽车的转向特性２·１4WS汽车与2WS汽车转向过程分析普通两轮转向汽车（2WS汽车）的前轮既可绕自身的轮轴自转又可绕主销相对于车身偏转，而后轮只能自转而不偏转。
当驾驶员转动方向盘后，前轮转向，改变了行驶方向，地面对前轮胎产生一个横向力，通过前轮作用于车身，使车身横摆，产生离心力，使后轮产生侧偏，改变前进方向，参与汽车的转向运动。
而4WS汽车的后轮与前轮一样，既可自转也能偏转。
当驾驶员转动方向盘后，前、后轮几乎同时转向，使汽车改变前进方向，实现转向运动。
2WS汽车在转向时，前轮作主动转向，后轮只是作被动转向。
显然，2WS汽车在转向过程中，从方向盘转动到后轮参与转向运动之间存在一定的滞后时间。
2WS汽车的这种相位滞后特性使汽车转向的随动性变差，并使汽车的转向半径增大。
另外，2WS汽车在高速行驶时，相对于一定的方向盘转角增量、车身的横摆角速度和横向加速度的增量增大，使汽车在高速行驶时的操纵性和稳定性变差。
而4WS汽车在转向时，前、后轮都作主动转向，在转向过程中，灵敏度高，响应快，有效地克服了上述缺点。
汽车转向系统车辆外文文献翻译、中英文翻译、外文翻译
汽车转向系统随着汽车电子技术的迅猛发展，人们对汽车转向操纵性能的要求也日益提高。
汽车转向系统已从传统机械转向、液压助力转向(Hydraulic Power Steering ,简称HPS) 、电控液压助力转向( Electric Hydraulic PowerSteering , 简称EHPS) ，发展到电动助力转向系统(Electric Power Steering ,简称EPS) ，最终还将过渡到线控转向系统(Steer By Wire ，简称SBW)。
机械转向系统是指以驾驶员的体力作为转向能源，其中所有传力件都是机械的，汽车的转向运动是由驾驶员操纵方向盘，通过转向器和一系列的杆件传递到转向车轮而实现的。
机械转向系由转向操纵机构、转向器和转向传动机械3大部分组成。
通常根据机械式转向器形式可以分为:齿轮齿条式、循环球式、蜗杆滚轮式、蜗杆指销式。
应用最广的两种是齿轮齿条式和循环球式(用于需要较大的转向力时) 。
在循环球式转向器中，输入转向圈与输出的转向摇臂摆角是成正比的;在齿轮齿条式转向器中，输入转向圈数与输出的齿条位移是成正比的。
循环球式转向器由于是滚动摩擦形式，因而正传动效率很高，操作方便且使用寿命长，而且承载能力强，故广泛应用于载货汽车上。
齿轮齿条式转向器与循环球式相比，最大特点是刚性大，结构紧凑重量轻，且成本低。
由于这种方式容易由车轮将反作用力传至转向盘，所以具有对路面状态反应灵敏的优点，但同时也容易产生打手和摆振等现象，且其承载效率相对较弱，故主要应用于小汽车及轻型货车上，目前大部分低端轿车采用的就是齿轮齿条式机械转向系统。
随着车辆载重的增加以及人们对车辆操纵性能要求的提高，简单的机械式转向系统已经无法满足需要，动力转向系统应运而生，它能在驾驶员转动方向盘的同时提供助力，动力转向系统分为液压转向系统和电动转向系统2 种。
其中液压转向系统是目前使用最为广泛的转向系统。
液压转向系统在机械系统的基础上增加了液压系统，包括液压泵、V 形带轮、油管、供油装置、助力装置和控制阀。
机械类英语论文及翻译
Mechanical DesignAbstract:A machine is a combination of mechanisms and other components which transforms, transmits. Examples are engines, turbines, vehicles, hoists, printing presses, washing machines, and movie cameras. Many of the principles and methods of design that apply to machines also apply to manufactured articles that are not true machines. The term "mechanical design" is used in a broader sense than "machine design" to include their design. the motion and structural aspects and the provisions for retention and enclosure are considerations in mechanical design. Applications occur in the field of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as switches, cams, valves, vessels, and mixers.Keywords: Mechanical Design ；Rules for Design ；Design ProcessThe Design ProcessDesigning starts with a need real.Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly.In the design preliminary stage, should allow to design the personnel fullyto display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.When the general shape and a few dimensions of the several components become apparent, analysis can begin in earnest. The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight, and a competitive cost. Optimum proportions and dimensions will be sought for each critically loaded section, together with a balance between the strengths of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles of mechanics, such as those of static for reaction forces and for the optimum utilization of friction; of dynamics for inertia, acceleration, and energy; of elasticity and strength of materials for stress and deflection; of physical behavior of materials; and of fluid mechanics for lubrication and hydrodynamic drives. The analyses may be made by the same engineer who conceived the arrangement of mechanisms, or, in a large company, they may be made by a separate analysis division or research group. Design is a reiterative and cooperative process, whetherdone formally or informally, and the analyst can contribute to phases other than his own. Product design requires much research and development. Many Concepts of an idea must be studied, tried, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems.Product liability suits designers and forced in material selection, using the best program. In the process of material, the most common problems for five (a) don't understand or not use about the latest application materials to the best information, (b) failed to foresee and consider the reasonable use material may (such as possible, designers should further forecast and consider due to improper use products. In recent years, many products liability in litigation, the use of products and hurt the plaintiff accused manufacturer, and won the decision), (c) of the materials used all or some of the data, data, especially when the uncertainty long-term performance data is so, (d) quality control method is not suitable and unproven, (e) by some completely incompetent persons choose materials.Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to thesuitable procedure, may greatly reduce the lawsuit the quantity.May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and the basic understanding.Finally, a design based upon function, and a prototype may be built. If its tests are satisfactory, the initial design will undergo certain modifications that enable it to be manufactured in quantity at a lower cost. During subsequent years of manufacture and service, the design is likely to undergo changes as new ideas are conceived or as further analyses based upon tests and experience indicate alterations. Sales appeal.Some Rules for DesignIn this section it is suggested that, applied with a creative attitude, analyses can lead to important improvements and to the conception and perfection of alternate, perhaps more functional, economical,and durable products.To stimulate creative thought, the following rules are suggested for the designer and analyst. The first six rules are particularly applicable for the analyst.1. A creative use of need of physical properties and control process.2. Recognize functional loads and their significance.3. Anticipate unintentional loads.4. Devise more favorable loading conditions.5. Provide for favorable stress distribution and stiffness with minimum weight.6. Use basic equations to proportion and optimize dimensions.7. Choose materials for a combination of properties.8. Select carefully, stock and integral components.9. Modify a functional design to fit the manufacturing process and reduce cost.10. Provide for accurate location and noninterference of parts in assembly.Machinery design covers the following contents.1. Provides an introduction to the design process , problem formulation ,safety factors.2. Reviews the material properties and static and dynamic loading analysis ,Including beam , vibration and impact loading.3. Reviews the fundamentals of stress and defection analysis.4. Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design of rotation machinery.5. Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses ,and surface fatigue.6. Investigates shaft design using the fatigue-analysis techniques.7. Discusses fluid-film and rolling-element bearing theory and application8. Gives a thorough introduction to the kinematics, design and stress analysis of spur gears , and a simple introduction to helical ,bevel ,and worm gearing.9. Discusses spring design including compression ,extension and torsion springs.10. Deals with screws and fasteners including power screw and preload fasteners.11. Introduces the design and specification of disk and drum clutches and brakes.Machine DesignThe complete design of a machine is a complex process. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge.One of the first steps in the design of any product is to select the material from which each part is to be made. Numerous materials are available to today's designers. The function of the product, its appearance, the cost of thematerial, and the cost of fabrication are important in making a selection. A careful evaluation of the properties of a. material must be made prior to any calculations.Careful calculations are necessary to ensure the validity of a design. In case of any part failures, it is desirable to know what was done in originally designing the defective components. The checking of calculations (and drawing dimensions) is of utmost importance. The misplacement of one decimal point can ruin an otherwise acceptable project. All aspects of design work should be checked and rechecked.The computer is a tool helpful to mechanical designers to lighten tedious calculations, and provide extended analysis of available data. Interactive systems, based on computer capabilities, have made possible the concepts of computer aided design (CAD) and computer-aided manufacturing (CAM). How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved.This generally is through the oral discussion, the schematic diagram and the writing material carries on.If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainlycannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.外文论文翻译译文机械设计摘要：机器是由机械装置和其它组件组成的。
真正的四轮驱动车辆外文文献翻译、中英文翻译
资料来源：True Four Wheel Drive System For Vehicle Four Wheel Drive System For Vehicle真正的四轮驱动车辆ABSTRACTA drive train for a four wheel drive vehicle including a front difforential engaged with a front drive shaft and front axles through a front differential gear set. The front differential includes a front bi-directional overrunning clutch that con-trols transmission of torque transfer between the front drive shaft and the front axles. A rear differential is engaged with rear axles and the transmission through a rear differential gear set. The rear differential includes a rear bi-directional over-running clutch that controls torque transfer between the trans-mission and the rear axles. The differentials are configured with a gear ratio that is within five percent of a l: 1 gear ratio.TRUE FOUR WHEEL DRIVE SYSTEM FOR VEHICLERELATED APPLICATIONThis application is related to and claims priority from U.S. Provisional Application 61/677,820, the disclosure of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTIONThe invention relates to drive systems and, more particularly, to an improved drive system designed to provide substantially true four wheel drive capability.BACKGROUNDprovide four wheel drive capability. Those systems are all designed to engage all four wheels but also allow a speed differential across the axle. However, many of those systems do not provide true four wheel drive where each wheel pro-vides substantially the same speed during all drive conditions. Instead, the systems permit some degree of slippage.Current Four Wheel Drive Bi-Directional Overrun-ning Clutch SystemsI illustrates the drive system for a conventional four wheel drive vehicle with a front bi-directional over-rul111ing clutch. The drive system includes four wheels. The rear left wheel RLW is connected to a rear differential RD through a rear left axle RLA. The right rear wheel RRW is com1ected to the rear differential RD through a rear right axle RRA. The front left wheel FLW is col111ected to a front dif-ferential FD through a front left axle FLA. The front right wheelFRW is connected to the front differential FD through a front right axle FRA.mission T through a rear drive shaft RDS. The front differen-tial FD is connected to the transmission T through a front drive shaft EDS.Straight Line Operation:During straight line driving while the vehicle is in a four wheel on demand mode (i.e., four wheel drive engages only when needed) both rear wheels RLW, RRW are the primary drive wheels and are co1111ected through the rear differential RD to rotate at the same speed. In a non-slip condition of the rear wheels, the front drive shaft FDS is engaged to the front differential FD, but the front axles FLA, FRA are not engaged with the front differential. That is, the front axles FLA, FRA and front wheels FLW, FRW are gen-erally in an overrun condition such that the front differential FD is not driving the front axles FLA, FRA and, therefore, not transmitting any torque to the front wheels. This means that the front wheels FLW. FRW are free to rotate at their actual ground speeds.In order for the front wheels to be engaged, the rear wheels must slip (break traction) or spin increase speed approximately 20% faster than the front wheels. While driv-ing in a straight line, once the rear wheels slip 20%, the overrunning condition in the front differential ED is over-come and both front axles are engaged. This results in the transmission T transmitting torque to the front wheels thru the front drive which is geared in a way that decreases the vehicles ground speed. When the ground speed has increased so as to cause the rear wheel speed to be rotating less than 20% faster than the ground speed, or the speed of the rear wheel has decreased so as to be rotating less than 20% faster than the ground speed, the front wheels will start to overrun again and no torque will be transmitted to the front wheels.Turning Operation:In a comer all four wheels are trying to rotate at different speeds, This is shown on the chart in FIG. 4 which depicts wheel revolutions vs. turning radius for all four wheels. For a vehicle with alocked rear axle or solid axle (i.e., an axle where the rear axles RLA, RRA are connected, either physically or through gearing, such that they always rotate at the same speed) the ground speed is dictated by the rear outside wheel due to vehicle dynamics (i.e., the rear outside wheel has to cover more circumferential distance than the rear inside wheel when turning around a common axis.) Since both rear wheels are rotating at the same speed and the rear outside wheel is the drivewheel the rear inside wheel is beginuing to scrub or drag on the ground. This can cause inefficiencies, turf wear and/or tire wear.The primary reason conventional bi-directional ovemnming clutch four wheel drive systems have a 20% under drive is for turning. With the rear outside wheel dictat-ing ground speed the front inside wheel will go slower than the rear outside wheel as shown in FIG. 4. If there is no under drive the bi-directional oveITllllling clutch for the front inside axle would engage and begin to drive torque. This would cause the front inside wheel to travel at an incorrect speed and would create inefficiencies, turf wear, tire wear and, more importantly, torque steer.As mentioned above, during a tum the rear outside wheel is dictating ground speed, the rear inside wheel is scrubbing or dragging, and the front wheels are overrunning. Referring to FIG. 5 which depicts the percentage difference between the front and rear wheel speeds versus the turning radius of a locked rear axle, once the rear outside wheel slips or spins a certain percentage, dictated by vehicle geometry and turning radius. the bi-directional overru1ming clutch con-trolling the transfer of torque to the front inside wheel will engage and drive torque through the front inside wheel At this time both rear wheels and the front inside wheel are driving torque and their speed is dictated by the drive line, not ground speed. The front outside wheel is still ovemmning allowing it to spin at the rotational speed dictated by ground speed and vehicle geometry. When both rear wheels and the front inside wheel slip a certain percentage, again dictated by vehicle geometry and the turning radius, the bidirectional clutch con-trolling torque transfer to the front outside wheel will engage and torque will be transmitted to all four wheels, even though three of the wheels would be slipping.WedgingThe existing drive system is prone to a condition called wedging. Wedging occurs when torque is being driven through the bidirectional over-numing clutch and a rapid direction change occurs. This can cause the rollers in the clutch to be positioned or locked on the wrong side of the clutch profile preventing the output hubs from overru1ming. The effect causes the front drive to act like a solid axle, but with the 20% speed difference in the drive line it results in scrubbing of the front tires. This condition can cause exces-sive tire wear and turf wear. This also effects steering effort and stability of the vehicle. The vehicle will try to maintain a straight line due to the effect of the front drive acting like a solid axle.Because of the wedging condition in the current systems precautions are put into place to help reduce wedging. One of these precautions is the use of a cut-off switch so that when the vehicle is shifted from the forward direction to the reverse direction so as to automatically disengage the bi-directional overrum1ing clutch (for example, shutting off the coil that is indexing the roll cage). This system also uses the cut-off switch when transitioning from the reverse direc-tion to the forward direction. Another way to reduce wedging is the use of a switch, when the brakes are applied, that will interrupt power to the 4 wheel drive system. Many other methods can be used to reduce wedging, but none are 100% percent effective with the 20% difference in drive line speeds.Conventional Drive Systems:A common conventional drive system would have the same vehicle layout as in FIG. 1, but the mechanisms in the front and rear differentials would be different. Most com-mon drive systems have an open differential with the ability to be locked into a solid axle in both the front and rear differen-tials. The drive line in a conventional system would also be using a drive line that is geared to a 1: 1 ratioStraight Line Operation:During straight line driving while the vehicle is in four wheel drive and all the axles are unlocked, all four wheels are rotating at the same speed. This is due to the drive line being geared at 1:1 ratio and the front and rear differen-tials are being driven at the same speed and no differentiation is needed across the axles. This is also the case when any or both of the front and rear differentials are in a locked position creating a solid axle.Turning operation:Conventional four wheel drive systems will nor-mally have the rear differential locked and the front drive will be in the open state until the solid axle mode is selected by the user. During turning with a solid axle in the rear differential and an open differential in the front, only one tire is turning at the correct ground speed. Due to vehicle dynamics the rear outside wheel is considered the drive wheel and is turning at ground speed. The inside rear wheel is being driven at the same speed as the rear outside, but the ground speed is slower. This causes the inside rear wheel to scrub or slip during a tum. (0023] Since the two front wheels are connected to an open differential, they are allowed to differentiate across the axle, However, the differential is beingdriven at an incorrect speed. That is, the front open differential takes the input speed and averages it across the axle. In a normal non slip condition the average speed across the axle is centered about the middle of he vehicle. Since the rear outside wheel is traveling at a different speed ( or arc) than the average of the two front wheels, both front wheels are scrubbing when in a tum caus-ing un-needed drive line torque or drive line bind.Once the operator selects the solid axle mode of the vehicle, both front wheels are locked together and they now rotate at the same speed. When turning, the outside front wheel is going slower than what ground speed dictates, thus causing the wheel to scrub. At the same time the inside front wheel is going faster than the ground speed dictates causing it to, likewise, scrub.Due to the wheels being driven at the wrong speeds in a comer, conventional drive systems are not very efficient. They cause severe turf damage or wear due to the tires scrub-bing. They also cause tire wear due to the scrubbing. The tires being driven at the wrong speeds also cause issues with steer-ing and turning performance of the vehicle. The difference between ground and actual wheel speed results in the wheels trying to straighten the vehicle out. This cause's increased wear in steering components, as well as rider fatigue since increased input is needed to maintain the vehicle in the tum. Many manufacturers have added power steering to try to minimize operator input when cornering because of the four wheel drive operations.A need therefore exists for an improved four wheel drive system that incorporates bi-directional overrunning clutches in a drive system that minimizes scrubbing in all wheels while permitting 1.1 or near 1: 1 gear ratio between the front and rear axles.SUMMARY OF THE INVENTIONThe present invention is directed to drive train for a four wheel drive vehicle. The drive train includes a front drive shaft connected to a transmission. Two front axles with each axle connected to a corresponding front wheel. A front dif-ferential is engaged with the front drive shaft and the front axles through a front differential gear set. The front differen-tial includes a front bi-directional overrunning clutch that controls transmission of torque transfer between the front drive shaft and the front axles.The front bi-directional ovemmning clutch includes a front clutch housing connected to the front drive shaft so as to be rotatable by the front drive shaft, the front clutch hous-ing including an inner cam surface. A front roller assembly is located inside the front clutch housing andadjacent to the cam surface. The front roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage, the rollers are rotatable inside the slots. A plurality of springs are arranged in the roll cage to position the rollers within the slots. The roll cage is rotatable within the front clutch housing. (0029] Two front hub are located in the front clutch hous-ing. Each hub is positioned radially inward from a set of the rollers located between an outer surface of the front hub and the im1er cam surface. Each front hub is engaged with an axial end of one of the front axles so as to rotate in combination with the axle. The front hubs are independently rotatable within the roll cage and the front clutch housing.A front engagement control assembly is located within the housing and controls engagement and disengage-ment of the front bi-directional overrunning clutch. The front engagement control assembly includes an electromechanical device that is controllable for impeding rotation of the roll cage relative to the front clutch housing so as to index the roll cage relative to the front clutch housing.When the engagement control assembly is activated and the roll cage is indexed relative to the clutch housing, the front bi-directional overrunning clutch is configured to trans-mit torque from the front drive shaft to the front axles when the front clutch housing is rotating faster than the front axles. Also, when the vehicle is traveling straight the front differen-tial is configured to begin to transmit torque from the front drive shaft to the front axles at a first speed.The gear train including two rear axles, each axle com1ected to a corresponding rear wheel.A rear differential is engaged with the rear axles and the transmission through a rear differential gear set. The rear differential including a rear differential housing and a rear bi-directional overrunning clutch that controls torque transfer between the transmission and the rear axles.The rear bi-directional overrunning clutch includes a rear clutch housing located within the rear differential !mus-ing and rotatable by the transmission, the rear clutch housing including an inner cam surface. A rear roller assembly is located inside the rear clutch housing and adjacent to the cam surface. The rear roller assembly includes a roll cage with a plurality of rollers arranged in two sets within slots formed in the roll cage. The rollers are rotatable inside the slots. A plurality of springs are arranged so as to position the rollers within the slots. The roll cage is rotatable within the rear clutch housing.Two rear hubs are located in the rear clutch housing. Each hub is positioned radially inwardfrom a set of the rollers located between an outer surface of the rear hub and the im1er cam surface. Each rear hub is engaged with an axial end of one of the rear axles so as to rotate in combination with the axle. The rear hubs are independently rotatable within the roll cage and the rear clutch housing.The rollers in each set of the rear roller assembly are adapted to wedgingly engage the corresponding rear hub to the rear clutch housing when one of either the rear hub or rear clutch housing is rotating faster than the other so as to trans-mit torque from whichever is faster to whichever is slower.The differentials are configured such that when the vehicle is traveling straight and the rear differential is trans-mitting torque to the rear axles. The rear differential is con-figured to rotate the rear axles at a second speed, and where the difference between the first speed and the second speed is five percent or less. In one preferred embodiment, the differ-ence between the first speed and the second speed is less than about three percent. In another embodiment there is substan-tially no difference between the first speed and the second speed.In one embodiment, the front bi-directional over-running clutch includes an armature plate that is engaged or connected with the front roll cage such that the armature plate rotates with the roll cage. The front engagement control assembly impedes rotation of the roll cage relative to the front clutch housing by engaging the amiature plate so as to index the roll cage relative to the clutch housing.Preferably the hubs are substantially coaxially aligned with each other within the housing. and are adapted to rotate about a common axis within the housing.In one embodiment, the rear differential is part of a transaxle which is engaged with the transmission. 。
转向系设计英文文献及翻译
Fundamentals of AutomobileToday is average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: engine, body, chassis and electrical and electronic equipment(Fig.1.1).1 EngineThe engine acts as the power unit. The internal combustion engine is most common: this obtain its power by burning a liquid fuel inside the engine cylinder. There are two types of engines: gasoline engine (also called a spark ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the transmission.2 BodyAn automobile body is a sheet metal shell with windows, doors, a hood, and a trunk deck built into it. It provides a protective covering for the engine, passengers, and cargo. The body is designed to keep passengers safe and comfortable. The body styling provides an attractive, colorful, modern appearance for the vehicle.3 chassisThe chassis is an assembly of those systems that are the major operating parts of a vehicle. The Chassis includes the transmission, suspension, steering, and brake system.3.1 TransmissionThe transmission system comprises clutch, gearbox, propeller shaft, rear axle and differential and the driven road wheels.ClutchThe clutch or torque converter has the task of disconnecting and connecting the engine's power from and to the driving wheels of the vehicle. This action may be manual or automatic.GearboxThe main purpose of the gearbox is to provide a selection of gear ratios between the engine and driving wheels, so that the vehicle can operate satisfactorily under all driving conditions. Gear selection may be done manually by the driver or automatically by a hydraulic control system.Propellor shaftThe function of the propeller (drive) shaft is to transmit the drivefrom the gearbox to the input shaft of the rear axle and differential assembly. Flexible joints allow the rear axle and wheels to move up and down without affecting operation.The role of the drive shaft from the transmission the driving force transmitted to the rear axle input shaft and the differential assembly. Universal joint allows the rear axle and wheels move up and down without affecting operation.Rear axle and differentialThe rear axle and differential unit transmits the engine's rotational power through 90 from propshaft to axle shaft to axle shaft to road wheels. A further function is to allow each driven wheel to turn at a different speed; essential when cornering because the outer wheel must turn further than the inside wheel. A third function is to introduce another gear ratio for torque multiplication.3.2 SuspensionThe axles and wheels are isolated from the chassis by a suspension system . The basic job of the suspension system is to absorb the shocks caused by irregular road surfaces that would otherwise be transmitted to the vehicle and its occupants, thus helping to keep the vehicle on a controlled and level course, regardless of road conditions.3.3 SteeringThe steering system, under the control of the driver at the steering wheel, provides the means by which the front wheels are directionally turned. The steering system may be power assisted to reduce the effort required to turn the steering wheel and make the vehicle easier to manoeuvre.3.4 BrakesThe braking system on a vehicle has three main functions. It must be able to reduce the speed of the vehicle, when necessary; it must be able to stop the car in as short a distance as possible; it must be able to hold the vehicle stationary. The braking action is achieved as a result of the friction developed by forcing a stationary surface(the brake lining)into contact with a rotating surface(the drum or disc).Each wheel has a brake assembly of either the drum type or the disc type, hydraulically operated when the driver applies the foot brake pedal.4 Electrical Equipment and InstrumentationThe electrical system supplies electricity for the ignition, horn, lights, heater, and starter. The electricity level is maintained by a charging circuit. This circuit consists of a battery, and an alternator (or generator). The battery stores electricity. The alternator changes the engine's mechanical energy into electrical energy and recharges the battery.The motor vehicle incorporates a number of electrical devices that are used for:Battery charging –alternator and regulator.Engine purposes –starting and ignition.Safety and convenience –lighting, horn, wipers, washers etc.Driver information –instrumentation and warning lamps.Of these devices instrumentation is, perhaps, most influenced by the advance of microelectronics. The basic electromechanical systems of:Speedometer –for indicating vehicle speed.Engine oil pressure –warning lamp or gauge to show operating limits.Engine coolant temperature –warning lamp or gauge to show operating limits.Battery charging –warning lamp or gauge to indicate satisfactory/unsatisfactory action.Fuel tank content –gauge to show amount of fuel in the fuel tank.are giving way to computerized vehicle management information centres.The Steering System1 The Steering GearThe steering gear mechanism enables the driver to turn the front wheels of the car. The mechanism consists of a steering gear box, pitman arm, drag link, tie rods, steering arms, and steering knuckles, the latter supporting the front wheels(Fig.6.1).Turning the steering wheel turns the steering shaft to which a worm gear is attached within the steering gear box. The steering worm moves a roller through a part of an arc, the motion of which is transmitted to the pitman arm, which moves back and forth across the width of the frame. Several arrangements of rods and levers are in common use but, in general, a drag link, connected to the pitmen arm, transmits the movement to tie rods which are connected to the steering arms. Sideward movement of the steering arms turns the steering knuckles, and the wheels, as they are pivoted on front end support mechanism.There are two types of steering system: manual steering system and power steering system. In the manual type, the driver does all the work of turning the steering wheel, steering gears, wheels, and tires. In the power type, hydraulic fluid assists the operation so that the driver's effort is reduced.Mechanical steering system: And changes the transmission systemby the diverter to be composed.Diverter: By the steering wheel, the steering wheel steering axle, changes meshing to pay (diverter) to be composed.Steering transmission system: By drop arm (drop arm), drag link, drag link arm, about trapezoidal arm, steering knuckle tie rod, if a dry bulb joint composes.Power steering system: Changes the augmenter constitution by mechanical steering system Canada.A typical power steering system needs a power steering pump and reservoir in addition to the steering gear(Fig.6.2). These parts store the hydraulic fluid and provide the hydraulic pressure to assist steering. In most instances, a V-belt from the engine power the hydraulic pump. Hoses lead from the pump to the steering gear and back to the pump.In steering gear box the gear is slightly larger and has other parts. The wormshaft is the same in both systems. Instead of a ball nut, though, the power steering system uses a power piston or rack piston in steering gear box. The power piston has teeth on one side that meshwith the sector teeth. The forward and backward motion of the power piston moves the sector, pitman shaft, and steering linkage.The power steering gear also uses a control valve to send hydraulic fluid into the steering gear at the right time. When the steering wheel starts to move in either direction, the valve opens its ports to sent fluid under pressure into the main chamber of the steering gear. The fluid pushes against the power piston and assists the motion of the steering wheel.Fig.6.2 In an integral power steering system, the power and control are in the same housing as the steering gear2 Front-GeometryThe front wheels are arranged at various angles to the car frame to provide good steering control and stability. The angles are discussed in the following order: caster, camber, steering axis inclination, toe, and turning radius.Caster is the slant of the kingpin forward at the bottom(Fig.6.3). (NOTE: Modern passenger car does not use a kingpin in an independently mounted front wheel suspension, but reference to its former position helps to clarify some front end concepts. The positionof the kingpin would be on a direct line drawn between the two ball joints). The front wheels, when provided with the proper amount of caster, will align themselves in the direction in which the car is moving. Too much caster will cause hard steering and shimmy at low speed. Too little caster will cause wander or weave at high speed and erratic steering when applying the brakes.Camber is the angle between a vertical line and a line drawn through the center of the wheel(Fig.6.4). The top of the wheel is inclined away from the car. The purpose of camber is to place the center of the tire directly under the extended line of the kingpin for easier steering. This places the weight of the car directly over the pivot point.Steering Axis Inclination is the outward tilt of the bottom of the kingpin toward the wheel(Fig.6.5). Modern engineering practice is to minimize camber in order to reduce uneven tire wear, and increase theFig.6.3 Caster Fig.6.4 Camber angular inclination of the kingpin to place its centerline directly under the center of the tire for ease in steering.Steering axis inclination also provides steering stability by raisingthe entire front end of the vehicle during a turn. Gravity causes the spindle ends to tend to return to their straight ahead position. This force is not enough to cause steering, but is enough to provide excellent directional stability. Steering axis inclination is probably a more important steering stability factor than caster.Toe-in is the difference in distance between the front and rear of the front tires, measured at spindle height(Fig.6.6). That is, the wheels are aimed slightly in as if to cross each other, it seems to cross each other's path. Due to compression of the steering linkage parts, the front wheels tend to turn out or away from each other. To offset this, they are provided with a small amount of toe-in. In operation, the wheels travel parallel paths and no side scuffing occurs.Fig.6.5 Steering axis inclinationTurning Radius, or toe-out on turns, is needed when turning a corner. Because the outside wheel on a curve turn about a longer arcthan does the inside wheel, it is necessary to have the inside wheel turn at a sharper angle to prevent tire scuffing and wear. To obtain this action, the steering arms are set at an angle to the wheels. Although the tie rod moves each arm an equal distance, the angular movement is unequal and the wheels toe-out. The sharper the turning angle, the more toe-out results.Fig.6.6 Toe-in汽车部件目前大多数的汽车由超过15000个各自独立的零部件组成，这些零部件必须一起配合工作。