某乘用车转向柱助力式转向系统设计【三维CATIA模型】【4张CAD图纸+PDF图】
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本科毕业论文（设计）中期检查报告 本科毕业论文（设计）中期检查报告论文题目 某乘用车转向柱助力式转向系统设计 班 级姓 名 院（系）导 师报告时间1论文工作是否按开题报告预定的内容及进度安排进行1.1 预定内容及进度第1 - 3 周：查阅相关资料，撰写开题报告第4 - 8 周：确定总体方案，进行转向系统设计计算；第9 - 11 周：对转向梯形进行优化设计；第12-15 周：三维实体建模，绘制二维工程图；第16-18 周：撰写毕业设计论文，复查设计内容，准备答辩。1.2 实际内容及进度第1 - 3 周：查阅相关资料，撰写开题报告；第4 - 8 周：确定总体方案，进行转向系统设计计算；第9 - 12 周：三维实体建模；1.3 实际设计与报告预定的差异1.3.1在内容继续按照开题报告上拟定内容进行；1.3.2 进度安排上，先进行了转向系统的三维模型的建立，后期再对转向梯形进行优化设计，对转向节进行有限元分析，最后对转向系统的三维模型进行修改和完善；2目前已完成的研究工作及结果（1）了解了乘用车转向系统的传动形式，位置差异，以及在不同位置以各种方式进行助力的转向系统；（2）初步建立了转向系统的三维模型；3后期拟完成的研究工作及进度安排（1）拟完成的研究工作：3.1.1对转向梯形进行优化设计；3.1.2对转向节进行有限元分析；3.1.3对转向系统的三维模型进行修改和完善；3.1.4绘制二维工程图；3.1.5撰写毕业论文；（2）进度安排：第12 - 14 周：对转向梯形进行优化设计，对转向节进行有限元分析；第14 - 15 周：三维模型的修改和完善；第16 - 18 周：撰写毕业设计论文，复查设计内容，准备答辩。4存在的困难与问题（1）部分设计数据的选定范围，加工制造过程中各个部件的合理性和可行性存在问题；（2）通过观察实体模型以及查阅资料，选取合理参数 5如期完成全部论文工作的可能性按照中期拟定工作安排，可如期完成论文工作；中期报告检查组意见： 组长（签字）： 年 月 日- 5 - 毕业论文（设计）开题报告 本科毕业论文（设计）开 题 报 告论文题目 某乘用车转向柱助力式转向系统设计 班 级姓 名 院（系）导 师开题时间- 0 -1课题研究的目的和意义随着近些年来社会生活的汽车化, 汽车的保有量不断增加, 由此造成交通错综复杂, 使得转向盘的操作频率增大, 这就需要减轻驾驶疲劳,提高操纵的轻便性和灵活性, 对动力转向系统的要求也越来越高, 现今广泛使用的液压式动力向系统存在着制造工艺复杂, 对密封要求严格、维修保养困难等缺陷, 已不能满足日益发展的要求, 同时随着电子技术在发动机、变速器、制动器和悬架等系统的广泛应用, 电动助力转向(Electric Power Steering, 简称 EPS) 技术应运而生, 成为世界汽车技术发展的研究热点。国内研究EPS的主要是几所高校(如清华大学、合肥工业大学、北京理工大学、华南理工大学、武汉理工大学等),且大都局限于理论和计算机仿真。1-3。电动助力转向系统较传统的液压动力转向优越很多: 结构简单，车辆布置设计容易，节约燃料, 能够提高主动安全性, 并且有利于环保, 是一项紧扣现代汽车发展主题的高新技术, 因此它有逐步取代传统液压动力转向的趋势。2电动转向助力按助力位置不同可分为转向柱助力式、小齿轮助力式、双小齿轮助力式以及齿条助力式。此次设计的目的是设计一套转向柱助力式转向系统，确定总体结构方案，而后在方案基础上转向系统的设计计算以及转向梯形4的优化设计，从实际驾驶的舒适性及安全性能角度出发，进行优化设计5和可行性分析，建立三维实体模型。2国内外研究现状目前，国外 EPS 的机械结构部分都相对成熟完善，各派系各零部件企业都有自己的独特之处。主要发展方向集中在控制策略、性能匹配以及可靠性等方面。早期 EPS简单的助力曲线早已不能适应当代汽车的要求，目前 EPS 不仅仅是提供转向助力，而是与整车操稳性能相匹配，综合各种影响因素，从而在某些工况下通过对转向系统施加阻尼或是补偿等，以获得更好的驾驶感觉。EPS 产品基本上都能实现转向助力功能, 但也存在一定问题, 如转向盘抖振、噪声大、左右转向不对称等。在产业化方面, 整车企业在电控技术及 EPS 的行业标准方面存在滞后性, EPS 研发单位与整车企业的全面合作尚不够深入, 因此其样机得不到全面的考核,涉及整车操纵稳定性能方面的研究较少。为了适应市场潮流，国内诸多企业也开始 EPS 的研发。但都是处于起步阶段，大多处在设计和性能验证阶段，只有少数企业将管柱助力式 EPS 应用在量产车型上。6EPS 系统通常由传感器 (车速传感器、转矩传感器、转向角传感器)、电子控制器 ECU、执行器 (电动机、电磁离合器和减速机构) 等 3 部分组成。72.1 扭矩传感器在现有技术基础上,扭矩传感器将向低价格和多功能两个方向发展8。2.1.1 低价格传感器该种传感器是在目前批量生产的扭矩传感器的基础上,进行技术革新, 通过采用新的材料, 减少组成传感器的零件数量, 从而降低传感器的生产成本而形成的。但是它只能测出扭矩信号,而不能测量转角。2.1.2 多功能传感器随着车辆底盘控制系统的发展, 除需要知道转向盘力矩信号外,还迫切需要转向盘转角信号, 供EPS、AFS (Active Front Wheel Steering) 和 ESP(Electronic StabilityProgram)等控制器使用。为满足功能要求, 并提高传感器的安装方便性, 降低成本,需要在扭矩传感器的基础上, 集成转角传感器。2.2 电机电动助力转向系统得到了广泛应用, 它不但被安装在微型车上, 还应用于经济性轿车, 并逐渐向中级轿车和高级轿车上发展。随着车辆质量和体积的增加, 对电机的输出扭矩提出了更高的要求。最初电机的输出电流是 25 A, 现在已经发展到了 90 A, 以后还有继续增大的趋势。2.3 ECU电动助力转向系统的 ECU 一般安装在驾驶舱中。但是在某些情况下, ECU 必须安装在发动机罩下面，在这种情况下, 就应该提高 ECU 的防水性能和耐高温性能。同时, 还要增加一个温度传感器, 直接测量 ECU 的环境温度, 并根据环境温度的高低,采取相应的措施, 保护 ECU。3. 本课题的研究内容及技术方案本论文主要包括转向柱助力式转向系统的总体设计、转向梯形的优化设计和转向系统完整的三维实体模型，并绘制工程图。3.1转向系统的总体设计3.1.1扭矩传感器扭矩传感器的功能是测量驾驶员作用在转向盘上的力矩的大小，是EPS的主输入信号之一。考虑主副电压输出特性，耐久可靠性能。3.1.2电动机电动机输出适宜的辅助力矩，要求电流转速、电流扭矩特性曲线符合性能、耐久可靠性要求。3.1.3减速机构减速机构与电动机相连，起减速增扭的作用，对传动效率，耐磨性能有一定的要求。3.1.3装配后整车转向性能必须符合国家车辆管理部门对整车的强制检验项目要求、整车操纵稳定性要求。3.2转向梯形的优化设计1）转向梯形优化设计的模型的建立。2）转向梯形的数学模型的建立。3）利用MATLAB进行分析9，得出优化解。4. 本设计的特色1）建立在电动助力的基础上，符合节能环保和科学技术发展的的要求。2）通过对转向柱助力式转向系统的总体设计，转向梯形的优化设计，与汽车整体转向系统的工作实况结合，对实际工程设计有很大帮助。3）利用MATLAB软件进行分析优化，得出设计的最优结果。5. 进度安排第1 - 3 周：查阅相关资料，撰写开题报告；第4 - 8 周：确定总体方案，进行转向系统设计计算；第9 - 11 周：对转向梯形进行优化设计；第12-15 周：三维实体建模，绘制二维工程图；第16-18 周：撰写毕业设计论文，复查设计内容，准备答辩。6. 参考文献1 闫俊，张欣：汽车电动助力转向技术分析 北京交通大学 机械与电子控制工程学院 北京2 余卓平 孟 涛，陈 慧，张立军：电动助力转向系统的技术发展趋势 同济大学汽车学院 200509043黄榕清，向铁明，许迎东：电动助力转向的原理及发展 华南理工大学 汽车工程学院广东 广州 4 张习泉：转向梯形应用简析 成都市工业职业技术学校汽车工程系 成都5 李玉民1，李旭宏1，过学迅2：转向梯形驱动机构的运动分析及优化设计 1.东南大学交通学院 南京 2武汉理工大学 6 杨洪斌：汽车转向管柱的有限元分析及设计优化 四川绵阳三力股份有限公司 绵阳 7 罗新闻：汽车可变转向系统结构及工作原理 2011128 易爱斌：转向柱式电动助力转向（C-EPS）系统的技术分析与技术确认研究华中科技大学 机械工程 200608289 杨俊治1，杨文兴2，周强1 2：基于MATLAB的转向梯形机构的优化研究1.兰州电源车辆研究所有限公司 2.兰州理工大学 机电工程学院开题报告检查组意见：（以下空46行文字） 组长（签字）： 年 月 日（此行置于页面底部分）- 3 -某乘用车转向柱助力式转向系统设计,报告人：,课题研究的目的和意义,驾驶舒适,节能环保,C-EPS,安全性能,结构简单,转向梯形,总体方案,国外 EPS 的机械结构部分都相对成熟完善，各派系各零部件企业都有自己的独特之处。 国内的EPS开发处于起步阶段，大多处在设计和性能验证阶段。,国内外研究现状,发展方向 控制策略 性能匹配 可靠性等方面,存在的问题, 转向盘抖振 噪声大 左右转向不对称等,设计内容及方案,总体方案设计,转向梯形的优化设计,包括转向系统各个部件的参数的选定； 对机械传动部分的设计；,转向梯形的设计与计算； 基于MATLAB软件分析的优化设计；,END, The motor turning systemAlong with automobile electronic technology swift and violent development, the people also day by day enhance to the motor turning handling quality request. The motor turning system changed, the hydraulic pressure boost from the traditional machinery changes (Hydraulic Power Steering, is called HPS), the electrically controlled hydraulic pressure boost changes (Elect ric Hydraulic Power Steering, is called EHPS), develops the electrically operated boost steering system (Elect ric Power Steering, is called EPS), finally also will transit to the line controls the steering system (Steer By Wire, will be called SBW).The machinery steering system is refers by pilots physical strength achievement changes the energy, in which all power transmission all is mechanical, the automobile changes the movement is operates the steering wheel by the pilot, transmits through the diverter and a series of members changes the wheel to realize. The mechanical steering system by changes the control mechanism, the diverter and major part changes the gearing 3 to be composed.Usually may divide into according to the mechanical diverter form: The gear rack type, follows round the world -like, the worm bearing adjuster hoop type, the worm bearing adjuster refers sells the type. Is the gear rack type and follows using the broadest two kinds round the world -like (uses in needing time big steering force).In follows round the world -like in the diverter, the input changes the circle and the output steering arm pivot angle is proportional; In the gear rack type diverter, the input changes the turn and the output rack displacement is proportional. Follows round the world -like the diverter because is the rolling friction form, thus the transmission efficiency is very high, the ease of operation also the service life are long, moreover bearing capacity, therefore widely applies on the truck. The gear rack type diverter with follows round the world -like compares, the most major characteristic is the rigidity is big, the structure compact weight is light, also the cost is low. Because this way passes on easily by the wheel the reacting force to the steering wheel, therefore has to the pavement behavior response keen merit, but simultaneously also easy to have phenomena and so on goon and oscillation, also its load bearing efficiency relative weak, therefore mainly applies on the compact car and the pickup truck, at present the majority of low end passenger vehicle uses is the gear rack type machinery steering system. Along with the vehicles carrying capacity increase as well as the people to the vehicles handling quality request enhancement, the simple mechanical type steering system were already unable to meet the needs, the power steering system arise at the historic moment, it could rotate the steering wheel while the pilot to provide the boost, the power steering system divides into the hydraulic pressure steering system and the electrically operated steering system 2kinds.Hydraulic pressure steering system is at present uses the most widespread steering system.The hydraulic pressure steering system increased the hydraulic system in the mechanical system foundation, including hydraulic pump, V shape band pulley, drill tubing, feed installment, boost installment and control valve. It with the aid of in the motor car engine power actuation hydraulic pump, the air compressor and the generator and so on, by the fluid strength, the physical strength or the electric power increases the pilot to operate the strength which the front wheel changes, enables the pilot to be possible nimbly to operate motor turning facilely, reduced the labor intensity, enhanced the travel security.The hydraulic pressure boost steering system from invented already had about half century history to the present, might say was one kind of more perfect system, because its work reliable, the technology mature still widely is applied until now. It takes the power supply by the hydraulic pump, after oil pipe-line control valves to power hydraulic cylinder feed, through the connecting rod impetus rotation gear movement, may changes the boost through the change cylinder bore and the flowing tubing head pressure size the size, from this achieved changes the boost the function. The traditional hydraulic pressure type power steering system may divide into generally according to the liquid flow form: Ordinary flow type and atmospheric pressure type 2 kind of types, also may divide into according to the control valve form transfers the valve type and the slide-valve type.Along with hydraulic pressure power steering system on automobile daily popularization, the people to operates when the portability and the road feeling request also day by day enhance, however the hydraulic pressure power steering system has many shortcomings actually: Because its itself structure had decided it is unable to guarantee vehicles rotates the steering wheel when any operating mode, all has the ideal operation stability, namely is unable simultaneously to guarantee time the low speed changes the portability and the high speed time operation stability;The automobile changes the characteristic to drive the pilot technical the influence to be serious; The steering ratio is fixed, causes the motor turning response characteristic along with changes and so on vehicle speed, transverse acceleration to change, the pilot must aim at the motor turning characteristic peak-to-peak value and the phase change ahead of time carries on certain operation compensation, thus controls the automobile according to its wish travel. Like this increased pilots operation burden, also causes in the motor turning travel not to have the security hidden danger; But hereafter appeared the electrically controlled hydraulic booster system, it increases the velocity generator in the traditional hydraulic pressure power steering system foundation, enables the automobile along with the vehicle speed change automatic control force size, has to a certain extent relaxed the traditional hydraulic pressure steering system existence question.At present our country produces on the commercial vehicle and the passenger vehicle uses mostly is the electrically controlled hydraulic pressure boost steering system, it is quite mature and the application widespread steering system. Although the electrically controlled hydraulic servo alleviated the traditional hydraulic pressure from certain degree to change between the portability and the road feeling contradiction, however it did not have fundamentally to solve the HPS system existence insufficiency, along with automobile microelectronic technology development, automobile fuel oil energy conservation request as well as global initiative environmental protection, it in aspect and so on arrangement, installment, leak-proof quality, control sensitivity, energy consumption, attrition and noise insufficiencies already more and more obvious, the steering system turned towards the electrically operated boost steering system development.The electrically operated boost steering system is the present motor turning system development direction, its principle of work is: EPS system ECU after comes from the steering wheel torque sensor and the vehicle speed sensor signal carries on analysis processing, controls the electrical machinery to have the suitable boost torque, assists the pilot to complete changes the operation. In the last few years, along with the electronic technology development, reduces EPS the cost to become large scale possibly, Japan sends the car company, Mitsubishi Car company, this field car company, USs Delphi automobile system company, TRW Corporation and Germanys ZF Corporation greatly all one after another develops EPS.Mercedes2Benz 和Siemens Automotive Two big companies invested 65,000,000 pounds to use in developing EPS, the goal are together load a car to 2002, yearly produce 300 ten thousand sets, became the global EPS manufacturer. So far, the EPS system in the slight passenger vehicle, on the theater box type vehicle obtains the widespread application, and every year by 300 ten thousand speed development.Steering is the term applied to the collection of components, linkages, etc. which allow for a vessel (ship, boat) or vehicle (car) to follow the desired course. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.The most conventional steering arrangement is to turn the front wheels using a handoperated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rearwheel steering. Tracked vehicles such as tanks usually employ differential steering that is, the tracks are made to move at different speeds or even in opposite directions to bring about a change of course.Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side. This motion applies steering torque to the kingpins of the steered wheels via tie rods and a short lever arm called the steering arm.Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. This is a variation on the older worm and sector design; the steering column turns a large screw (the worm gear) which meshes with a sector of a gear, causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis of the sector moves the pitman arm, which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are recirculated.The rack and pinion design has the advantages of a large degree of feedback and direct steering feel; it also does not normally have any backlash, or slack. A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars. The recirculating ball design also has a perceptible lash, or dead spot on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.The steering linkage connecting the steering box and the wheels usually conforms to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually traveling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns.As vehicles have become heavier and switched to front wheel drive, the effort to turn the steering wheel manually has increased - often to the point where major physical exertion is required. To alleviate this, auto makers have developed power steering systems. There are two types of power steering systemshydraulic and electric/electronic. There is also a hydraulic-electric hybrid system possible.A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the steering wheel. Electric power steering (EPS) is more efficient than the hydraulic power steering, since the electric power steering motor only needs to provide assist when the steering wheel is turned, whereas the hydraulic pump must run constantly. In EPS the assist level is easily tunable to the vehicle type, road speed, and even driver preference. An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid.An outgrowth of power steering is speed adjustable steering, where the steering is heavily assisted at low speed and lightly assisted at high speed. The auto makers perceive that motorists might need to make large steering inputs while manoeuvering for parking, but not while traveling at high speed. The first vehicle with this feature was the Citron SM with its Diravi layout, although rather than altering the amount of assistance as in modern power steering systems, it altered the pressure on a centring cam which made the steering wheel try to spring back to the straight-ahead position. Modern speed-adjustable power steering systems reduce the pressure fed to the ram as the speed increases, giving a more direct feel. This feature is gradually becoming commonplace across all new vehicles.Four-wheel steering (or all wheel steering) is a system employed by some vehicles to increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed.In most four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the Alternatively, several systems, including Delphis Quadrasteer and the system in Hondas Prelude line, allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. This allows the vehicle to turn in a significantly smaller radius sometimes critical for large trucks or vehicles with trailers.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( Elect ric Hydraulic PowerSteering ， 简称EHPS) ， 发展到电动助力转向系统(Elect ric 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。它借助于汽车发动机的动力驱动液压泵、空气压缩机和发电机等，以液力、气力或电力增大驾驶员操纵前轮转向的力量，使驾驶员可以轻便灵活地操纵汽车转向，减轻了劳动强度，提高了行驶安全性。液压助力转向系统从发明到现在已经有了大约半个世纪的历史，可以说是一种较为完善的系统，由于其工作可靠、技术成熟至今仍被广泛应用。它由液压泵作为动力源，经油管道控制阀向动力液压缸供油，通过活塞杆带动转向机构动作，可通过改变缸径及油压的大小来改变助力的大小，由此达到转向助力的作用。传统液压式动力转向系统一般按液流的形式可以分为:常流式和常压式2 种类型，也可根据控制阀形式分为转阀式和滑阀式。随着液压动力转向系统在汽车上的日益普及，人们对操作时的轻便性和路感的要求也日益提高，然而液压动力转向系统却存在许多的缺点: 由于其本身的结构决定了其无法保证车辆在任何工况下转动转向盘时，都有较理想的操纵稳定性，即无法同时保证低速时的转向轻便性和高速时的操纵稳定性; 汽车的转向特性受驾驶员驾驶技术的影响严重; 转向传动比固定，使汽车转向响应特性随车速、侧向加速度等变化而变化，驾驶员必须提前针对汽车转向特性幅值和相位的变化进行一定的操作补偿，从而控制汽车按其意愿行驶。这样增加了驾驶员的操纵负担，也使汽车转向行驶中存在不安全隐患;而此后出现了电控液压助力系统，它在传统的液压动力转向系统的基础上增加速度传感器，使汽车能够随着车速的变化自动调节操纵力的大小，在一定程度上缓和了传统的液压转向系统存在的问题。目前我国生产的商用车和轿车上采用的大多是电控液压助力转向系统，它是比较成熟和应用广泛的转向系统。尽管电控液压助力装置从一定程度上缓解了传统的液压转向中轻便性和路感之间的矛盾，然而它还是没有从根本上解决HPS 系统存在的不足，随着汽车微电子技术的发展，汽车燃油节能的要求以及全球性倡导环保，其在布置、安装、密封性、操纵灵敏度、能量消耗、磨损与噪声等方面的不足已越来越明显，转向系统向着电动助力转向系统发展。电动助力转向系统是现在汽车转向系统的发展方向，其工作原理是:EPS 系统的ECU 对来自转向盘转矩传感器和车速传感器的信号进行分析处理后，控制电机产生适当的助力转矩，协助驾驶员完成转向操作。近几年来，随着电子技术的发展，大幅度降低EPS的成本已成为可能，日本的大发汽车公司、三菱汽车公司、本田汽车公司、美国的Delphi 汽车系统公司、TRW公司及德国的ZF 公司都相继研制出EPS。Mercedes2Benz 和Siemens Automotive 两大公司共同投资6500万英镑用于开发EPS ，目标是到2002 年装车，年产300 万套，成为全球EPS 制造商。到目前为止，EPS 系统在轻微型轿车、厢式车上得到广泛的应用，并且每年以300 万台的速度发展。Steering is the term applied to the collection of components, linkages, etc. which allow for a vessel ( ship , boat ) or vehicle ( car ) to follow the desired course.转向是一个专业术语，适用于采集部件，联系等，其中允许一艘(舰船)或汽车(轿车)按照预期的方向行驶. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.一个例外的情况是铁路运输由路轨组合在一起铁路道岔提供转向功能。Many modern cars use steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side.许多现代轿车使用齿轮齿条式转向器，在方向盘末端有转动齿轮;该齿轮带动齿条移动，它是一种线性的齿轮紧密配合，从一边到一边。这种运动把转矩通过转向横拉杆和一种叫做转向节臂的短形臂传递给转向轮的主销。mechanism, which is still found on trucks and utility vehicles.以前的设计往往采用循环球式转向器，而这种转向器仍然应用在卡车和多用途车辆。This is a variation on the older and thus steers the wheels.这是一种老式的螺母和齿扇设计，该转向管柱转动大螺丝(蜗轮)，它与一个齿扇齿轮啮合，当蜗轮转动时，齿扇也随之转动，一个安装在齿扇轴上且与转向联动有关的摇臂带动转向节臂 ，从而使车轮转动. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are recirculated.循环球式转向器通过安装滚珠减少螺母和螺杆之间的摩擦;两根导管和螺母内的螺旋管状通道组合成两条各自独立的封闭的钢球“流到”。The rack and pinion design has the advantages of a large degree of feedback and direct steering feel; it also does not normally have any , or slack.齿轮齿条式转向器设计具有很大程度的反馈和直接转向路感;它也通常不会有任何反弹，或呆滞。A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.缺点是，它是不可调的，因此当它磨损唯一的解决办法更换。The recirculating ball mechanism has the advantage of a much greater , however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars.循环球式转向器的优点是机械优势，因此，它被使用在较大较重的车辆，而齿轮齿条式原本仅限于较小和较轻;由于几乎普遍采用动力转向系统，不过，这已不再是一个重要的优势，导致越来越多地在新型汽车应用齿轮齿条式转向器。 to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly.循环球式转向器设计在中心也有明显的冲击，或死点。凡一分钟交替方向盘出不来并不移动转向机构;这是很容易可调螺杆的端部来减少磨损，但它并不能完全消除或机制开始磨损很快。 This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage.这项设计目前仍在使用中，在卡车和其他大型车辆，也应用于迅速转向，路感与稳健性，可维护性，和机械的优势相比不太重要的场合。 The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim).较小程度的反馈，这样的设计也有时是一种优点;当前轮碰撞时，使用齿轮齿条转向的司机只有自己的大拇指受伤，造成方向盘揭开一边突然(因为驾驶教练告诉学生把自己的大拇指在前面的方向盘，而非放在左右的内边缘). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.这种效果在像卡车一样的重型汽车更为明显;循环球式转向防止这种程度的反馈，只是因为它可以在正常情况下防止可取反馈。 转向连锁连接转向器和车轮通常符合一个阿克曼转向几何的变化，它交代了一个事实:当转向是，内轮转过的半径比外轮小得多，因此适合驾驶的直路，是不适合曲折。As vehicles have become heavier and switched to front wheel drive , the effort to turn the steering wheel manually has increased - often to the point where
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