汽车EPS转向系统与SBW
汽车EPS转向系统与SBW
汽车EPS转向系统与SBW目前，汽车转向系统一般采用动力转向系统，动力转向系统根据助力的方式可分为液压助力转向系统(HPS)、电控液压助力转向系统(EHPS）、电动助力转向系统(EPS)和线控转向系统(SBW )。
长久以来，汽车的动力转向系统一直采用液压助力转向系统，由于液压系统的诸多缺点，电动助力转向系统取代液压助力转向系统已经成为动力转向系统发展的必然趋势。
电动助力转向系统（EPS)电动助力转向系统完全取消了液压部件，整个系统由机械转向系统加上扭矩传感器、车速传感器、电机传感器、ECU、助力电机、离合器、减速器等组成。
基本工作原理是：转向盘转动时，扭矩传感器将检测到转向盘上的扭矩信号和转向信号传给ECU，ECU同时接受车速信号，据此决定助力电机的基本助力电流，然后一般还生成电机惯性补偿电流和阻尼补偿电流，总电流作为电机目标电流，通过ECU内部的电机驱动电路对电机进行扭矩控制。
根据电机布置位置不同，电动助力转向系统可分为：转向柱助力式、齿轮助力式、齿条助力式三种。
转向柱助力式EPS的电机固定在转向柱一侧，通过减速机构与转向轴相连，直接驱动转向轴进行助力转向。
齿轮助力式EPS的电机和减速机构与小齿轮相连，直接驱动齿轮助力转向。
齿条助力式EPS 的电机和减速机构则直．接驱动齿条提供助力。
电动助力转向系统的优点如下：1.效率可高达90％以上，液压动力转向效率一般在60%~70%：2．路感和回正性好，EPS结构简单，内阻小、回正性好，改善了汽车操纵稳定性：3.能耗少。
EPS只在转向时电机才提供助力，汽车油耗可降低3％左右：4.可独立于发动机工作，EPS以蓄电池为能源，以电机为动力元件，与发动机无关；5.对环境无污染。
液压助力转向系统液压管路接头存在油泄漏问题且液压管路不可回收：6.装配性好,易于布置，由于EPS主要部件（电机、减速器、传感器、电控单元等）可集成在一起，便于整车布置和装配：7.应用范围少，主要用于轿车和轻型货车，对电动汽车、混合动力车、燃料电池车是最佳选择。
(完整版)汽车转向系统最新毕业论文设计
优秀论文审核通过未经允许切勿外传开题报告一、背景、现状及发展趋势转向系统：用来改变或保持汽车行驶方向的机构称为汽车转向系统(steering system)。
汽车转向系统的功能就是按照驾驶员的意愿控制汽车的行驶方向。
汽车转向系统对汽车的行驶安全至关重要，因此汽车转向系统的零件都称为保安件。
汽车转向系统分为两大类：机械转向系统和动力转向系统。
完全靠驾驶员手力操纵的转向系统称为机械转向系统。
借助动力来操纵的转向系统称为动力转向系统。
动力转向系统又可分为液压动力转向系统和电动助力动力转向系统。
随着产业布局、产品结构的调整，就业结构也将发生变化。
企业对较高层次的第一线应用型人才的需求将明显增加，培养相当数量的具有高等文化水平的职业人才，成为迫切要求。
据统计，目前，我国技术工人中，高级技工占 3.5℅，中级工占35℅，初级工占60℅。
而发达国家技术工人中，高级技工占35℅，中级工占50℅，初级工占15℅。
这表明，我们的高级技工在未来5—10年内仍会有大量的人才缺口。
因此熟悉汽车转向系统，熟练掌握现代化汽车转向系统的设计、操作和维护的应用型高级技术人才成为社会较紧缺、企业最需要的人才。
随着汽车工业的迅速发展，转向装置的结构也有很大变化。
现代汽车转向装置的设计趋势主要向适应汽车高速行驶的需要、充分考虑安全性、轻便性、低成本、低油耗、大批量专业化生产发展。
通过本次毕业论文对转向系统进行进一步的了解，并且结合通过实习了解的知识对转向系统的可能出现的问题进行分析和解决方法，从而提高自身对转向系统的深入认识二、设计目的通过本次毕业设计使自己对汽车转向系统在故障诊断和维修方面有更为充分、细致的理解，进一步掌握转向系统的原理、应用和CADCAM软件应用。
三、设计工作1、概述2、转向系统现阶段的主要类型3、汽车转向系统可能出现的问题和分析4、汽车转向系统的新发展---整体式、半分置式及联阀式动力转向结构四、时间安排项目时间截点备注论文题目确定2011年2月25日开题报告2011年3月4日论文初稿2011年4月15日论文定稿2011年5月7日论文答辩2011年5月15日二次答辩2011年5月22日目录浅析汽车转向系统常见故障诊断与维修 (2)摘要 (2)绪论 (3)1 概述 (4)1.1 什么是汽车转向系统 (4)1.2 汽车转向系统概述 (4)1.3 转向系统简介及工作原理 (4)2 汽车转向系统的故障诊断 (10)2.1 机械转向系故障诊断 (10)2.2 动力转向系故障诊断 (12)2.3 转向系仪器检测 (14)3对汽车转向系统的故障进行维修 (16)3.1机械转向系的维修 (16)3.2动力转向系的维修 (19)4结论……………………………………………………………………………………………22谢辞 (23)参考文献 (24)英文资料 (25)中文翻译 (30)浅析汽车转向系统常见故障诊断与维修摘要：本文阐述了汽车转向系统各个部分的作用、组成、主要构造、工作原理、及可能出现的故障，同时提出了对出现的故障进行维修的可行方案；采用了理论与实际相结合的方法，对每个问题都有良好的认识，对所学内容进行了良好的总结归纳，以此进一步熟悉掌握汽车转向系统的各方面知识，深化巩固所学知识，做到理论与实际相结合，在理论学习的前提下，用实际更好的理解所学内容。
汽车EPS系统原理
汽车EPS系统原理从上世纪50年代出现了汽车助力转向系统以来,经历了机械式、液压式、电控液压式等阶段,80年代人们开始研制电子控制式电动助力转向系统,简称EPS(ElectricPowerSteering)。
EPS 在机械式助力转向系统的基础上,用输入轴的扭矩信号和汽车行驶速度信号控制助力电机,使之产生相应大小和方向的助力,获得最佳的转向特性。
EPS用仅在转向时才工作的助力电机替代了在汽车运行过程中持续消耗能量的液压助力装置,简化了结构,降低了能耗,动态地适应不同的车速条件下助力的特性,操作轻便,稳定性和安全性好,同时,不存在油液泄漏和液压软管不可回收等问题。
可以说,EPS是集环保、节能、安全、舒适为一体的机电一体化设计。
电动助力转向系统EPS是当前世界最发达的转向助力系统,20世纪80年代,日本铃木公司首次开发。
因其具有独特的按需助力、随动跟踪、反映路感、节能高效、环保免维护、系统成本低等一系列优点,在中小排量汽车中即将以较大产品份额取代液压助力转向总成(HPS)。
与传统的转向系统相比较,汽车电动助力转向系统(EPS)结构简单,灵活性好,能充分满足汽车转向性能的要求,在操作的舒适性、安全性和节能、环保等方面显示出显著的优越性。
EPS的特点及工作原理(1)EPS系统的特点。
随着电子技术的发展,电子技术在汽车上的应用越来越广泛。
电动助力转向已成为汽车动力转向系统的发展方向。
由于采用动力转向可以减少驾驶员手动转向力矩,改善汽车的转向轻便性,因此在商用车、中高级轿车和轻型车上得到广泛的应用。
传统的动力转向系大多采用固定放大倍数的液压动力转向,缺点是不能实现汽车在各种车速下驾驶时的轻便性和路感。
为了克服以上缺点,研制出电子控制液压动力转向系(EHPS),使汽车在各种速度下都能得到满意的转向助力。
但EHPS系统结构更复杂、价格更昂贵,而且效率低、能耗大。
EPS是一种机电一体化的新一代汽车智能转向助力系统。
SBW_汽车转向技术的未来
的方式自动驾 驶车辆，使汽
基本控制器
回正力矩电机
车尽快恢复到
故障离合器
稳定状态。 转向执行
总成包括前轮
故障处理控制器
齿轮齿条 转向器
转角传感器、
转向执行电
机、转向电机 控制器和前轮 转向组件等。
汽车速度、加速度、 横摆角速度传感器
转向执行电机 转向桥机构总成
转向执行总成
图 1 SBW 的组成示意图
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1．SBW 的组成和工作原理
1）SBW 的组成 SBW 由方向盘总成、主控制器 （ECU） 和转向执行总成三个主要部 分以及自动防故障系统、电源系统等 辅助系统组成，如图 1 所示。 方向盘总成包括方向盘、方向盘 转角传感器、方向盘力矩传感器、方 向盘回正力矩电机和机械传动装置， 其主要功能是将驾驶员的转向意图 （通过测量方向盘转角） 转换成数字 信号并传递给主控制器，同时接收主 控制器传送来的控制信号，产生方向
发送命令，控制两个电机协调工作，
2）SBW 的工作原理
保证各种工况下都具有理想的车辆
当驾驶员转动方向盘时，方向盘
响应，减轻驾驶员对汽车转向特性随 转角传感器和方向盘力矩传感器将
车速变化而进行补偿的任务。主控制 测量到的方向盘转角和转矩转变成
器还可以对驾驶员的操作指令进行 电信号输入到 ECU，ECU 根 据 前 轮
盘回正力矩，以提供给驾驶员相应的 的功能是接收主控制器的命令，通过
“路感”信息。
转向电机控制器、转向执行电机来控
主控制器对采集的信号进行分 制转向车轮转动，实现驾驶员的转向
析处理，判别汽车的运动状态，向方 意图。同时，由前轮转角传感器将测
汽车电动助力转向系统的研究大学毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：汽车电动助力转向系统的研究文献、资料英文题目：The auto electric power steering system research 文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期：2017.02.14英文原文The auto electric power steering system researchAlong 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 hanged, the hydraulic pressure boost from the traditional machinery changes (Hydraulic Power Steering, is called HPS), the electrically controlled hydraulic pressure boost changes (Electronic Hydraulic Power Steering, is called EHPS), develops the electrically operated boost steering system (Electronic 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 pilot's 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 thehydraulic 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: ①Because 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;②The automobile changes the characteristic to drive the pilot technical the influence to be serious;③The 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 pilot's 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 andthe 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, US's Delphi automobile system company, TRW Corporation and Germany's ZF Corporation greatly all one after another develops EPS.Mercedes2Benz 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 ahand–operated 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 orrear–wheel 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 systems—hydraulic and electric/electronic. There is also ahydraulic-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 Citroën 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 Delphi's Quadrasteer and the system in Honda's 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.Electronic power steering systemWhat it isElectrically powered steering uses an electric motor to drive either the power steering hydraulic pump or the steering linkage directly. The power steering function is therefore independent of engine speed, resulting in significant energy savings.How it works :Conventional power steering systems use an engine accessory belt to drive the pump, providing pressurized fluid that operates a piston in the power steering gear or actuator to assist the driver.In electro-hydraulic steering, one electrically powered steering concept uses a high efficiency pump driven by an electric motor. Pump speed is regulated by an electric controller to vary pump pressure and flow, providing steering efforts tailored for different driving situations. The pump can be run at low speed or shut off to provide energy savings during straight ahead driving (which is most of the time in most world markets).Direct electric steering uses an electric motor attached to the steering rack via a gear mechanism (no pump or fluid). A variety of motor types and gear drives is possible. A microprocessor controls steering dynamics and driver effort. Inputs include vehicle speed and steering, wheel torque, angular position and turning rate.Working In Detail:A "steering sensor" is located on the input shaft where it enters the gearbox housing.The steering sensor is actually two sensors in one: a "torque sensor" that converts steering torque input and its direction into voltage signals, and a "rotation sensor" that converts the rotation speed and direction into voltage signals. An "interface" circuit that shares the same housing converts the signals from the torque sensor and rotation sensor into signals the control electronics can process.Inputs from the steering sensor are digested by a microprocessor control unit that also monitors input from the vehicle's speed sensor. The sensor inputs are then compared to determine how much power assist is required according to a preprogrammed "force map" in the control unit's memory. The control unit then sends out the appropriate command to the "power unit" which then supplies the electric motor with current. The motor pushes the rack to the right or left depending on which way the voltage flows (reversing the current reverses the direction the motor spins). Increasing the current to the motor increases the amount of power assist.The system has three operating modes: a "normal" control mode in which left or right power assist is provided in response to input from the steering torque and rotation sensor's inputs; a "return" control mode which is used to assist steering return after completing a turn; and a "damper" control mode that changes with vehicle speed to improve road feel and dampen kickback.If the steering wheel is turned and held in the full-lock position and steering assist reaches a maximum, the control unit reduces current to the electric motor to prevent an overload situation that might damage the motor. The control unit is also designed to protect the motor against voltage surges from a faulty alternator or charging problem.The electronic steering control unit is capable of self-diagnosing faults by monitoring the system's inputs and outputs, and the driving current of the electric motor. If a problem occurs, the control unit turns the system off by actuating a fail-safe relay in the power unit. This eliminates all power assist, causing the system to revert back to manual steering. A dash EPS warning light is also illuminated to alert the driver. To diagnose the problem, a technician jumps the terminals on the service check connector and reads out the trouble codes.Electric power steering systems promise weight reduction, fuel savings and package flexibility, at no cost penalty.Europe's high fuel prices and smaller vehicles make a fertile testbed for electric steering, a technology that promises automakers weight savings and fuel economy gains. And in a short time, electric steering will make it to the U.S., too. "It's just just a matter of time," says Aly Badawy, director of research and development for Delphi Saginaw Steering Systems in Saginaw, Mich. "The issue was cost and that's behind us now. By 2002 here in the U.S. the cost of electric power steering will absolutely be a wash over hydraulic."Today, electric and hybrid-powered vehicles (EV), including Toyota's Prius and GM's EV-1, are the perfect domain for electric steering. But by 2010, a TRW Inc. internal study estimates that one out of every three cars produced in the world will be equipped with some form of electrically-assisted steering. The Cleveland-based supplier claims its new steering systems could improve fuel economy by up to 2 mpg, while enhancing handling. There are true bottom-line benefits as well for automakers by reducing overall costs and decreasing assembly time, since there's no need for pumps, hoses and fluids.Another claimed advantage is shortened development time. For instance, a Delphi group developed E-TUNE, a ride-and-handling software package that can be run off a laptop computer. "They can take that computer and plug it in, attach it to the controller and change all the handling parameters -- effort level, returnability, damping -- on the fly," Badawy says. "It used to take months." Delphi has one OEM customer that should start low-volume production in '99.Electric steering units are normally placed in one of three positions: column-drive, pinion-drive and rack-drive. Which system will become the norm is still unclear. Short term, OEMs will choose the steering system that is easiest to integrate into an existing platform. Obviously, greater potential comes from designing the system into an all-new platform."We have all three designs under consideration," says Dr. Herman Strecker, group vice president of steering systems division at ZF in Schwaebisch Gmuend, Germany. "It's up to the market and OEMs which version finally will be used and manufactured.""The large manufacturers have all grabbed hold of what they consider a core technology," explains James Handysides, TRW vice president, electrically assisted steering in Sterling Heights, Mich. His company offers a portfolio of electric steering systems (hybrid electric, rack-, pinion-, and column-drive). TRW originally concentrated on what it still believes is the purest engineering solution for electric steering--the rack-drive system. The system is sometimes refered to as direct drive or ball/nut drive.Still, this winter TRW hedged its bet, forming a joint venture with LucasVarity. The British supplier received $50 million in exchange for its electric column-drive steering technology and as sets. Initial production of the column and pinion drive electric steering systems is expected to begin in Birmingham, England, in 2000."What we lack is the credibility in the steering market," says Brendan Conner, managing director, TRW/LucasVarity Electric Steering Ltd. "The combination with TRW provides us with a good opportunity for us to bridge that gap." LucasVarity currently has experimental systems on 11 different vehicle types, mostly European. TRW is currently supplying its EAS systems for Ford and Chrysler EVs in North America and for GM's new Opel Astra.In 1995, according to Delphi, traditional hydraulic power steering systems were on 7596 of all vehicles sold globally. That 37-million vehicle pool consumes about 10 million gallons in hydraulic fluid that could be superfluous, if electric steering really takes off.The present invention relates to an electrically powered drive mechamsm for providing powered assistance to a vehicle steering mechanism. According to one aspect of the presentinvention, there is provided an electrically powered driven mechanism for providing powered assistance to a vehicle steering mechanism having a manually rotatable member for operating the steering mechanism, the drive mechanism including a torque sensor operable to sense torque being manually applied to the rotatable member, an electrically powered drive motor drivingly connected to the rotatable member and a controller which is arranged to control the speed and direction of rotation of the drive motor in response to signals received from the torque sensor, the torque sensor including a sensor shaft adapted for connection to the rotatable member to form an extension thereof so that torque is transmitted through said sensor shaft when the rotatable member is manually rotated and a strain gauge mounted on the sensor shaft for producing a signal indicative of the amount of torque being transmitted through said shaft.Preferably the sensor shaft is non-rotatably mounted at one axial end in a first coupling member and is non-rotatably mounted at its opposite axial end in a second coupling member, the first and second coupling members being inter-engaged to permit limited rotation therebetween so that torque under a predetermined limit is transmitted by the sensor shaft only and so that torque above said predetermined limit is transmitted through the first and second coupling members.The first and second coupling members are preferably arranged to act as a bridge for drivingly connecting first and second portions of the rotating member to one another.Preferably the sensor shaft is of generally rectangular cross-section throughout the majority of its length.Preferably the strain gauge includes one or more SAW resonators secured to the sensor shaft.Preferably the motor is drivingly connected to the rotatable member via a clutch.Preferably the motor includes a gear box and is concentrically arranged relative to the rotatable member.Various aspects of the present invention will hereafter be described, with reference to the accompanying drawings, in which :Figure 1 is a diagrammatic view of a vehicle steering mechanism including an electrically powered drive mechanism according to the present invention,Figure 2 is a flow diagram illustrating interaction between various components of the drive mechanism shown in Figure 1 ,Figure 3 is an axial section through the drive mechanism shown in Figure 1, Figure 4 is a sectional view taken along lines IV-IV in Figure 3,Figure 5 is a more detailed exploded view of the input drives coupling shown in Figure 3, andFigure 6 is a more detailed exploded view of the clutch showing in Figure 3. Referring initially to Figure 1 , there is shown a vehicle steering mechanism 10 drivingly connected to a pair of steerable road wheels The steering mechanism 10 shown includes a rack and pinion assembly 14 connected to the road wheels 12 via joints 15. The pinion(not shown) of assembly 14 is rotatably driven by a manually rotatable member in the form of a steering column 18 which is manually rotated by a steering wheel 19.The steering column 18 includes an electric powered drive mechanism 30 which includes an electric drive motor (not shown in Figure 1) for driving the pinion in response to torque loadings in the steering column 18 in order to provide power assistance for the operative when rotating the steering wheel 19.As schematically illustrated in Figure 2, the electric powered drive mechanism includes a torque sensor20 whichmeasures the torque applied by the steering column 18 when driving the pinion and supplies a signal to a controller 40. The controller 40 is connected to a drive motor 50 and controls the electric current supplied to the motor 50 to control the amount of torque generated by the motor 50 and the direction of its rotation.The motor 50 is drivingly connected to the steering column 18 preferably via a gear box 60, preferably an epicyclic gear box, and a clutch 70. The clutch 70 is preferably permanently engaged during normal operation and is operative under certain conditions to isolate drive from the motor 50 to enable the pinion to be driven manually through the drive mechanism 30. This is a safety feature to enable the mechanism to function in the event of the motor 50 attempting to drive the steering column too fast and/or in the wrong direction or in the case where the motor and/or gear box have seized.The torque sensor 20 is preferably an assembly including a short sensor shaft on which is mounted a strain gauge capable of accurately measuring strain in the sensor shaft brought about by the application of torque within a predetermined range.Preferably the predetermined range of torque which is measured is 0-lONm; more preferably is about l-5Nm.Preferably the range of measured torque corresponds to about 0-1000 microstrain and the construction of the sensor shaft is chosen such that a torque of 5Nm will result in a twist of less than 2°in the shaft, more preferably less than 1 ° .Preferably the strain gauge is a SAW resonator, a suitable SAW resonator being described in WO91/13832. Preferably a configuration similar to that shown in Figure 3 of WO91/13832 is utilised wherein twoSAW resonators are arranged at 45° to the shaft axis and at 90°to one another.Preferably the resonators operate with a resonance frequency of between 200-400 MHz and are arranged to produce a signal to the controller 40 of 1 MHz ±500 KHz depending upon the direction of rotation of the sensor shaft. Thus, when the sensor shaft is not being twisted due to the absence of torque, it produces a 1 MHz signal.When the sensor shaft is twisted in one direction it produces a signal between 1.0 to 1.5 MHz. When the sensor shaft is twisted in the opposite direction it produces a signal between 1.0 to 0.5 MHz. Thus the same sensor is able to produce a signal indicative of the degree of torque and also the direction of rotation of the sensor shaft.Preferably the amount of torque generated by the motor in response to a measured torque of between 0-10Nm is 0-40Nm and for a measured torque of between l-5Nm is 0-25Nm.Preferably a feed back circuit is provided whereby the electric current being used by the motor is measured and compared by the controller 40 to ensure that the motor is running in the correct direction and providing the desired amount of power assistance. Preferably the controller acts to reduce the measured torque to zero and so controls the motor to increase its torque output to reduce the measured torque.A vehicle speed sensor (not shown) is preferably provided which sends a signal indicative of vehicle speed to the controller. The controller uses this signal to modify the degree of power assistance provided in response to the measured torque.Thus at low vehicle speeds maximum power assistance will be provided and a high vehicle speeds minimum power assistance will be provided.The controller is preferably a logic sequencer having a field。
EPS工作原理
EPS工作原理EPS（电动助力转向系统）工作原理EPS（Electric Power Steering）是一种采用电动机来辅助车辆转向的系统。
它通过电子控制单元（ECU）和传感器来感知驾驶员的转向意图，并根据车辆速度和转向角度等参数来调整电动助力转向的力度。
EPS的工作原理可以分为三个主要步骤：感知驾驶员的转向意图、计算所需的转向辅助力度、施加转向辅助力度。
1. 感知驾驶员的转向意图：在EPS系统中，有两种常见的转向传感器：扭矩传感器和转角传感器。
扭矩传感器通过感知驾驶员施加在转向盘上的转矩来判断其转向意图。
转角传感器则通过感知转向盘的角度变化来判断转向意图。
这些传感器将转向意图的信号传递给ECU。
2. 计算所需的转向辅助力度：ECU接收到转向意图的信号后，会根据车辆的速度、转向角度和其他传感器提供的数据来计算所需的转向辅助力度。
例如，在低速行驶时，ECU可能会增加转向辅助力度，以提供更大的转向力。
而在高速行驶时，ECU可能会减小转向辅助力度，以保持稳定性。
3. 施加转向辅助力度：根据计算得出的转向辅助力度，ECU会控制电动助力转向系统中的电动机来施加相应的力度。
电动助力转向系统通常由一个齿轮和一个电动助力转向机电组成。
电动助力转向机电通过与齿轮的配合来产生转向辅助力度，从而减轻驾驶员的转向力。
需要注意的是，EPS系统还会考虑其他因素，如车辆的动态特性、驾驶员的习惯和路面状况等，以提供更加智能和舒适的转向辅助。
总结起来，EPS工作原理是通过感知驾驶员的转向意图，计算所需的转向辅助力度，并通过电动助力转向系统施加相应的力度来辅助车辆转向。
这种系统可以提供更轻松、更精确的转向操作，提高驾驶的舒适性和安全性。
新能源汽车电气技术(第2版)课件：新能源汽车电动助力转向系统
四、EPS系统的优缺点
1.EPS系统具有以下优点： 与其他转向系统相比，该系统突出的优点表现在： 1）更加节省能源和环保。因为EPS没有液压器件，所以可算得上是标准 的“按需供能型”系统，即在转向的情况下系统才工作，而汽车停止时或者 直线运行时完全不消耗任何能量，这样一来耗能就会相对较少。因此与液压 动力系统进行比较，可以节约能源80%到90%。而在不转向时，EPS燃油消耗 会降低2.5%；在使用转向系统时，则会减少5.5%。另外又因为在-40℃的低 温的状况下，EPS也可以较好地工作，而传统的液压系统只有液压油预热后 才可以工作，由于EPS没有起动时的预热过程，所以节省了许多能量。EPS也 不存在液态油的泄漏问题，从而也不会对环境造成严重的污染，符合了环保 的设计理念。 2）助力效果相对更好。EPS可根据汽车运行的不同工况，通过优化设计 助力特性曲线，获得准确的助力，助力效果十分理想。同时还可以通过控制 阻尼系数减小因为路面的干扰对转向系统产生的影响，保障车辆低速行驶时 的轻便性，提高汽车高速行驶时的稳定性，进而提高汽车的转向性能。
六、电动助力转向系统（EPS）工作原理
转向器选择齿轮齿条式，转向盘转矩通过扭矩传感器来测得。当没有转向动作时，助力 电机不工作；当驾驶员有转向操作时，扭矩传感器发出一个电压信号，电子控制单元（ECU） 根据电压信号值推算得到转向盘转矩的大小及方向，同时，车速传感器将检测到的当前车速 传递到电子控制单元（ECU），电子控制单元（ECU）先根据车速选择与之对应的助力特性曲 线，再根据转向盘转矩进行运算处理，得到目标助力转矩的大小以及方向，再经过一系列计 算确定助力电机的旋转方向和驱动电流的大小，助力电机根据得到的驱动电流提供相应的助 力转矩，减速增扭后作用到转向轴上，为转向系统提供与工况相适应的助力。
EPS工作原理
EPS工作原理EPS（Electric Power Steering，电动助力转向系统）是一种通过电机来辅助转向的汽车转向系统。
它取代了传统的液压助力转向系统，具有更高的效率、更低的能耗和更好的响应性能。
EPS工作原理主要包括传感器、控制单元、电机和转向机构四个部分。
1. 传感器：EPS系统中的传感器用于感知驾驶员的转向意图和车辆的运动状态。
常见的传感器包括转向角传感器、转向力传感器和车速传感器。
转向角传感器用于测量方向盘的转角，转向力传感器用于测量驾驶员施加在方向盘上的力，而车速传感器用于测量车辆的速度。
2. 控制单元：EPS系统的控制单元负责接收传感器的信号，并根据这些信号计算出相应的转向助力。
控制单元采用电子控制器和算法来实现转向助力的精确控制。
通过对转向助力的控制，控制单元可以使驾驶变得更轻松、更舒适。
3. 电机：EPS系统中的电机是实现转向助力的关键部件。
电机通常安装在转向柱上，通过与转向机构相连，产生转向助力。
电机根据控制单元的指令，调整输出的扭矩大小和方向，以满足驾驶员的转向需求。
电机通常是一种无刷直流电机，具有高效率和快速响应的特点。
4. 转向机构：EPS系统的转向机构包括齿轮、齿条和传动装置等部件。
电机通过传动装置将扭矩传递给齿轮和齿条，从而实现转向助力。
转向机构的设计和传动比例决定了转向助力的大小和灵敏度。
EPS系统工作时，传感器感知驾驶员的转向意图和车辆的运动状态，并将这些信息传递给控制单元。
控制单元根据接收到的信号计算出合适的转向助力，并通过控制电机输出相应的扭矩。
电机将扭矩传递给转向机构，从而实现转向助力。
整个过程实时进行，以保证驾驶员的转向需求得到满足。
EPS工作原理的优点包括：1. 能耗低：相比传统的液压助力转向系统，EPS系统不需要额外的液压泵和液压油路，因此能耗更低。
2. 效率高：EPS系统利用电机直接产生转向助力，无需通过液压系统传递力量，因此效率更高。
3. 响应快：EPS系统的控制单元可以根据驾驶员的转向意图和车辆的运动状态实时调整转向助力，响应更快。
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汽车EPS转向系统与SBW
目前，汽车转向系统一般采用动力转向系统，动力转向系统根据助力的方式可分为液压助力转向系统(HPS)、电控液压助力转向系统(EHPS）、电动助力转向系统(EPS)和线控转向系统(SBW )。
长久以来，汽车的动力转向系统一直采用液压助力转向系统，由于液压系统的诸多缺点，电动助力转向系统取代液压助力转向系统已经成为动力转向系统发展的必然趋势。
电动助力转向系统（EPS)
电动助力转向系统完全取消了液压部件，整个系统由机械转向系统加上扭矩传感器、车速传感器、电机传感器、ECU、助力电机、离合器、减速器等组成。
基本工作原理是：转向盘转动时，扭矩传感器将检测到转向盘上的扭矩信号和转向信号传给ECU，ECU同时接受车速信号，据此决定助力电机的基本助力电流，然后一般还生成电机惯性补偿电流和阻尼补偿电流，总电流作为电机目标电流，通过ECU内部的电机驱动电路对电机进行扭矩控制。
根据电机布置位置不同，电动助力转向系统可分为：转向柱助力式、齿轮助力式、齿条助力式三种。
转向柱助力式EPS的电机固定在转向柱一侧，通过减速机构与转向轴相连，直接驱动转向轴进行助力转向。
齿轮助力式EPS的电机和减速机构与小齿轮相连，直接驱动齿轮助力转向。
齿条助力式EPS 的电机和减速机构则直．接驱动齿条提供助力。
电动助力转向系统的优点如下：
1.效率可高达90％以上，液压动力转向效率一般在60%~70%：
2．路感和回正性好，EPS结构简单，内阻小、回正性好，改善了汽车操纵稳定性：
3.能耗少。
EPS只在转向时电机才提供助力，汽车油耗可降低3％左右：
4.可独立于发动机工作，EPS以蓄电池为能源，以电机为动力元件，与发动机无关；
5.对环境无污染。
液压助力转向系统液压管路接头存在油泄漏问题且液压管路不可回收：
6.装配性好,易于布置，由于EPS主要部件（电机、减速器、传感器、电控单元等）可集成在一起，便于整车布置和装配：
7.应用范围少，主要用于轿车和轻型货车，对电动汽车、混合动力车、燃料电池车是最佳选择。
EPS历史与现状
EPS系统首先是在微型轿车上发展起来的，其主要原因是狭小的发动机舱空间给液压助力转向系统的安装带来了很大的麻烦。
EPS由于部件少，安装方便，非常适合在微型轿车上安装。
1988年2月，日本铃木公司首次在其Cervo轿车上安装了EPS系统，随后还应用在其Alto车上。
此后，EPS在日本得到迅速发展，如大发汽车公司的Mira轿车、三菱汽车公司的Minica轿车、本田公司的雅阁轿车等都先后安装了EPS系统。
欧、美等国的汽车公司对EPS的开发研究比日本晚10年时间，但是开发的力度较大，目前也有一些公司开发了EPS系统并装车销售。
美国的天合和德尔福等公司相继推出各自的产品，天合公司将航空技术应用于EPS系统的开发，于1996年推出自己EPS系统，并在福特Fiesta和马自达323F上进行试验：德尔福属下的Saginaw公司于1999年首次研制成功其电动助力转向系统产品E-Steerlm Electric
PowerSteering.德国的ZF公司研制出装配于不同类型轿车的EPS系统。
戴-克和西门子威迪欧两大汽车公司共同投资6500万英镑用于EPS的研究。
目前，我国部分高校和企业已经开始对EPS系统开展研究。
1998年吉林大学在国内率．先开展轿车EPS的研究，目前已做出样机并在捷达轿车、北斗星轿车和夏利2000纯电动轿车上进行了装车试验，取得了良好的试验效果。
清华大学目前也开发出EPS样机并在昌河铃木CH6350轿车上试验运行。
另外天津大学、北京科技大学、华中科技大学、江苏大学、合肥工业大学、武汉理工大学等院校也在开展EPS 的研究。
另外南方航空动力机械公司已开发出EPS系统，并进行小批量道路试验，上汽集团泛亚技术中心正在于国外公司进行EPS系统研究的立项工作。
目前，国内生产的昌河北斗星、上海大众途安、广州本田飞度、吉利豪情等轿车上已经安装了EPS 系统。
从发展趋势看，电动助力转向系统的应用范围正从最初的微型轿车向更大型轿车、客车和货车方向发展。
北京理工大学目前已经开展了电动大客车EPS系统的研究工作。
可以预见，在未来几年内，随着汽车对环保、节能和安全性要求的进一步提高，国内各大院校、研究所和企业必将掀起EPS研究的热潮。
EPS系统发展趋势
随着科学技术的发展，一种更新型的助力转向系统一线控转向系统(Steering ByWire，简称SBW）会逐渐得到人们的认可和采用。
线控转向系统中有两个电机，其中一个与汽车前轮转向机构相连接，作为转向执行机构：另一个电机直接与转向传动轴连接，为驾驶员提供路感力矩。
因此这种转向系统中的转向盘与转向轮之间没有机械连接，是断开的，通过CAN传输必要的信息，故也称柔性转向系统。
线控转向系统由于转向盘与转向轮之间没有机械连接，在系统设计上一般采用机械冗余或电气冗余措施。
线控转向系统有许多优点：
1.柔性转向能消除转向干涉问题，为实现多功能全方位的自动控制，以及汽车动态控制系统和汽车平顺性控制系统的系统集成提供了显著的先决条件。
2.对前轮驱动轿车，在安装发动机时需要考虑刚性转向轴占用空间，转向轴必须依据汽车是左侧驾驶还是右侧驾驶安装在发动机附近，设计人理各种需要安排部件。
而柔性转向去掉了原来转向系各个功能模块之间的刚性机械连接，大大方便了系统的总布置。
3.舒适性得到提高。
在刚性转向系统中，路面不平和转向轮的不平衡，可以回传到转向轴，而柔性系统不能。
4.转向回正力矩能够通过软件依据驾驶员的要求进行调整。
因此在不改变设计的情况下，可以个性化地适合特定的驾驶者和驾驶员环境，与转向有关的驾驶行为都可以通过软件来实现。
5.消除了碰撞事故中转向柱引起伤害驾驶员的可能性，不必设置转向防撞机构。
6.驾驶员腿部活动空间增加，出入更方便自由。
线控转向系统SBW将是EPS的未来发展方向，是未来的转向控制系统，能满足汽车对安全性（从汽车动态控制到防撞）和舒适性（从由电子高速公路控制的导航到自动驾驶系统）的更高要求。
信息来源：汽车与配件。