汽车电动助力转向系统（EPS）设计【齿轮齿条转向器】
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齿轮齿条转向器
汽车电动助力转向系统（EPS）设计【齿轮齿条转向器】
汽车
电动
助力
转向
系统
EPS
设计
齿轮
齿条
转向器
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System Overview Of Automobile Electric Power Steering Electric Power Steering system, EPS (Electric Power Steering, abbreviation) is a kind of rely on motor directly provide auxiliary torque of the Power Steering system, with the traditional HPS Hydraulic Power Steering system (Hydraulic Power Steering) compared to, EPS system has many advantages. EPS is mainly composed of torque sensor, speed sensor, motor, deceleration body and electronic control unit (ECU), etc. Development history of the development process of the car, the steering system has experienced four stages of development:From the initial mechanical Steering system (Manual Steering, MS) for the development of Hydraulic Power Steering system (Hydraulic Power Steering, referred to as HPS), then the electronically controlled Hydraulic Power Steering system (company Hydraulic Power Steering, the EHPS) and Electric Power Steering system (Electric Power Steering, hereinafter referred to as EPS).Mechanical steering system of automobile assembly, in the car parking and driving at low speed when the drivers steering load is too heavy, in order to solve this problem, the United States GM company pioneered in the 1950 s adopted the hydraulic power steering system on the car. However, hydraulic power steering system is unable to take into account the vehicle at low speed when the steering portability and high-speed stability, so in 1983, Japan Koyo company launched have speed induction function of electronically controlled hydraulic power steering system. This new type of steering system can provide decreased gradually with the increase of speed, steering, but complex, high cost, and cannot be overcome hydraulic system itself has many shortcomings, is a kind of between the hydraulic power steering and the transition between the electric power steering. In 1988, Japan Suzuki company first in the small car Cervo equipped with Koyo company research and development of steering power type electric power steering system; In 1990, the Japanese Honda company also adopted the independent research and development on the NSX sports cars of the rack power type electric power steering system, from then on, unveiled on auto electric power steering applications history. Type and advantages and disadvantages of our common power steering are mechanical hydraulic booster, electronic hydraulic power and electric power.The mechanical hydraulic boosterMechanical and hydraulic power is our one of the most common dynamical method, it was born in 1902, by the British Frederick w. Lanchester invention, and the earliest application is delayed for half a century later, the commercialization of the Chrysler 1951 mature hydraulic steering system is applied in the Imperial line disappears. Because the technology is mature and reliable, and low cost, has been widely spread.Mechanical hydraulic booster system main component of hydraulic pump, tubing, pressure fluid control valve, V belt, storage tanks, etc. This power is part of the engine power output into hydraulic pump pressure, auxiliary force on steering system, so that the tires.The electronic hydraulic pressure boostDue to mechanical hydraulic power consumption need sharp engine power, so people on the basis of mechanical hydraulic booster was improved, developed a more save energy consumption of electronic hydraulic power steering system. The system of the steering pump is no longer directly driven by the engine, but by the motor to drive, and on the basis of before equipped with the electric control system, make to the size of the auxiliary power is not only related to the steering Angle, also related to the speed. Mechanical structure increased hydraulic reaction equipment and flow distributing valve, the new electronic control system including the speed sensor, electromagnetic valve, steering ECU, etc.Electric powerEPS is the abbreviation of English for Electric Power Steering, Electric Power Steering system. Electric power steering system is the development direction of automobile steering system. The system provided by the electric power machine direct steering, eliminating the hydraulic power steering system required for the power steering pumps, hoses, hydraulic oil, conveyor belt and pulley mounted on the engine, save energy, and protect the environment. In addition, also has the easy, flexible assembly and under various conditions can provide steering characteristics. It is with these advantages, electric power steering system as a new steering technology, will challenge the everyone is very familiar with, have the hydraulic steering system with more than 50 years history.Driver in manipulation of the steering wheel steering, steering and steering wheel torque sensor detects the size of the torque, the voltage signal to the electronic control unit, the electronic control unit according to detect torque of the torque sensor voltage signals, the rotation direction and speed, etc., to the motor controller issued a directive, the motor output corresponding size and direction of the steering torque, thus generating auxiliary power. Cars dont turn, the electronic control unit is not issuing commands to the motor controller, motor does not work. Advantage advantages compared with traditional hydraulic power steering system, electric power steering system has the following advantages:1, only when the steering motor to provide power, can significantly reduce fuel consumptionTraditional hydraulic power steering system with the engine drives the steering pump, no matter to or not to consume power engine parts. And electric power steering system is powered by a motor in the steering, not to not waste energy. Therefore, the electric power steering system can reduce fuel consumption of the vehicle.Compared with hydraulic power steering system test shows that, when not to electric power steering can reduce fuel consumption by 2.5%; In turn, can be reduced by 5.5%.2, steering size can be adjusted by the software, to be able to take into account the steering portability and low speed when high speed steering stability, back is good performance.The traditional hydraulic power steering system provided by the steering size can change with the increase of speed. Although this makes the vehicle at low speed have good steering portability, but in high speed steering wheel is too light, have turned to FaPiao phenomenon, the driver without significant sense of road, reduce the stability of vehicle at high speed and the drivers sense of security.Electric power steering system provides convenient adjustment of size by software. At low speeds, the electric power steering system can provide larger steering, provide the vehicles steering portability; As speed increases, the electric power steering system to provide the steering can be gradually decreases, and turn to when the driver required to provide force will gradually increase, so the driver can feel obvious sense of road, enhances the stability of the vehicle.Electric power steering system can also exert certain additional back to positive torque and damping torque, making low speed when the steering wheel back to the middle position accurately, and can inhibit the high-speed rotating is steering wheel oscillation and overshoot in the process, both the return-to-center performance at high and low speed vehicles.3, compact structure, light quality, good production line assembly, easy to maintenanceCancelled the electric power steering system hydraulic steering oil pump, oil cylinder, hydraulic pipeline and oil tank, and the motor and deceleration institutions can make a whole, and the steering column and steering makes the entire steering system structure is compact, light quality, good on the production line of assembling, save time, easy to maintenance.4, through the program setup, easy to match with different models, electric power steering system can shorten the cycle of production and development.Because the electric power steering system has many advantages above, thus obtained is more and more widely used in recent years.Electric power steering system is on the basis of the mechanical steering system, install the motor and deceleration mechanism, torque Angle sensor, speed sensor and the electronic control unit (ECU) for ECU. Edit this section the characteristics of hydraulic power steering system has been developed for more than half a century, the technology has been quite mature. But with the development of the auto microelectronics technology, constantly improve to automobile energy saving and environmental protection requirement, the system of energy consumption and pollution to the environment may cause the inherent shortage is more and more obvious, cant completely meet the requirements of times development.Electric power steering system will be the latest power electronic technology and high performance motor control technology applied in automobile steering system, can significantly improve vehicle dynamic performance and static performance, enhance the drivers driving comfort and safety, reduce environmental pollution, etc. Once the system is put forward, therefore, is brought to the attention of many big car companies, and carry on research and development, the future of the steering system of electric power steering steering system will become mainstream, compared with the other steering system, the system highlights the advantage embodies in:A, reduce the fuel consumption.Engine to drive the hydraulic pump hydraulic power steering system, make the hydraulic oil flow ceaselessly, wasted energy. Instead of electric power steering system (EPS) only need to operation need motor provides energy, this energy can come from battery, also can come from the engine. Moreover, energy consumption is associated with the steering and the current speed of steering wheel. When the steering wheel does not turn, the motor doesnt work, need to start work under the influence of the motor in the control module and output the corresponding size and direction of the torque to produce power-assist steering torque, and the system output maximum steering torque, when the car spin with the change of the vehicle speed, output torque is also follow changes. The system realize the on-demand power, is the real on-demand power type (on demand) system. Car when starting a cold winter, the traditional hydraulic system response is slow, until after the hydraulic oil preheating can work normally. Because the electric power steering system design is not dependent on the engine and there is no hydraulic oil tube, is not sensitive to cold weather, the system can work even when to 40 , so provides quick cold start. Because the system does not start at the time of preheat, save the energy. Hydraulic pump is not used, to avoid the engine of parasitic energy loss, improve the fuel economy, and is equipped with electric power steering system of the vehicle and is equipped with hydraulic power steering system of vehicle contrast experiment shows that under the condition of not to, is equipped with electric power steering system of vehicle fuel consumption by 2.5%, in use to case, the fuel consumption was reduced by 5.5%.Second, strengthened to follow.In the electric power steering system, electric power machine attached directly to the steering mechanism can make the energy directly to the turning of the wheel. The system USES inertial shock absorber effect, make the reversal of the wheel and steering wheel shimmy water reducing greatly. So steering systems ability to resist disturbance greatly enhanced compared with the hydraulic power steering system, rotating torque generated by motor, without turning hysteresis effect of hydraulic power system, enhance the follow performance of steering wheel to the steering wheel.3, improve the steering characteristics are back.Until today, the development of the power steering system performance has reached the limit, the return-to-center characteristics of a electric power steering system has changed all that. When the driver to rotate the steering wheel Angle to loosen, the system can automatically adjust back to the middle of the wheel. The system also can let the engineers use software within the maximum adjustment to get the best design parameters are features. From low speed to high speed, and can get a bunch of return-to-center performance curve. Through flexible software programming and easy to get motor in various speed and torque under different shape features, the torque characteristics makes the system can significantly improve the steering ability, provides the steering is back to match the vehicle dynamic performance camera features. In the traditional hydraulic control system, to improve the features to be transformed mechanical structure of the chassis, it is difficult to implement.Fourth, improve the steering stability.Through to the car at high speed oversteering method to test stability characteristics of car. By using this method, high speed (100 km/h) of a cars on the corner of the excessive force it roll, in a short time since the return is in the process, the adoption of microcomputer control, makes the motor has higher stability and the driver feel more comfortable.5, provide flexible steering.Electric power steering system of the steering force from the motor. Through the software programming and hardware control, available to cover the entire speed variable steering force. Variable power shift depending on the size of the steering torque and speed. Whether parking, low speed or high speed, it can provide reliable, controllable good sense, and easier to yard operation.For traditional hydraulic system, variable steering torque is very difficult to achieve and the cost is very high, in order to get the variable steering torque, must add an additional controller and other hardware. But in the electric power steering system, variable steering torque are usually written to the control module, can be obtained through the rewrite of the software, and the required fee is very small.Six, adopting green energy, to meet the requirements of modern cars.Electric power steering system application of the cleanest power as an energy source, completely banned the hydraulic equipment, there is no leakage of liquid oil in the hydraulic power steering system problems, can say the system is complied with the era of green trend. The system because it has no hydraulic oil, no hoses, pumps and seals, avoid the pollution. Tubing and hydraulic steering system use polymer recycling, not easy to damage to the environment.Seven, system structure is simple, takes up the space is little, convenient layout, superior performance.Because the system has a good modular design, so dont need to redesign a different system, testing, processing, etc., not only save the cost, also for the design of different system offers great flexibility, and easier to assembly production line. Because there is no oil pump, tubing, and the pulley on the engine, allows engineers to design the system have more leeway, and the system control module, can design together and gear rack or separate design, very high space utilization ratio of engine parts. Saves the system installed on the engine belt pulley and the oil pump, set aside the space can be used to install other parts. Many consumers when buying a car is very concerned about the maintenance of vehicles. Cars with electric power steering system without oil pump, no hose connection, can reduce many worries. In fact, the traditional hydraulic steering system, hydraulic pressure oil pump and hose accidents accounted for 53% of the entire system failure, such as hose leakage and oil pump oil leak.Eight, assembly production line.Hydraulic system of electric power steering system has no need of pump, tubing, flow control valves, storage tanks and other components, the number of parts is greatly reduced, reducing the workload of assembly, save the assembly time, improve the assembly efficiency.Electric power steering system since the mid - 1980 - s since the early put forward, as the development direction of automobile steering system, will replace the existing mechanical steering system, hydraulic power steering system and electric control hydraulic steering system. Working principle of electric power steering system are as follows: first, the torque sensor to measure the pilot control torque on the steering wheel, the speed sensor to measure the current driving speed of vehicles, the then pass these two signal to ECU; ECU according to the built-in control strategy, calculates the ideal goal of steering torque, instruction for motor into current; Then, motor power torque by the retarding mechanism of amplification effect on the mechanical steering system, and the drivers manipulation of the moment overcomes the steering resistance moment together, realize the steering of the vehicle.Edit this section of the key technologies of electric power steering system key technology mainly includes two aspects of hardware and software.Mainly related to sensor, motor and ECU hardware technology. Sensor is the source of the whole system, and its accuracy and reliability is very important. Motor is the actuator of the system, its performance is good or bad determines the performance of the system. ECU is the operation center of the whole system, so the performance and reliability of the ECU is crucial.Software technology mainly includes the control strategy and fault diagnosis and protection of two parts. Motor control strategy is used to determine the current goals and track the current, make the motor output corresponding torque. Fault diagnosis and protection procedures used for the operation of the monitoring system, and alarm when necessary and some protection measures for its implementation. The working process of the electric power steering system (EPS) as a substitute for traditional hydraulic system products has entered into automobile manufacturing field. In contrast to the previous forecast, EPS is not only suitable for small cars, and some medium-sized cars are suitable for 12 v electric system installation. EPS system contains the following components: the torque sensor, the detection of steering wheel movement and the movement of vehicle; Electronic control unit, according to the torque sensor for signal of the size of the computing power; Electronic control unit (ECU) for motors, according to the torque output values formation; Produced by a reduction gear, and improve the motor power, and transmits it to the steering gear.Other vehicle system control algorithm input information is provided by the car CAN bus (for example, the steering Angle and vehicle speed, etc.). Motor driver also need other information, such as motor rotor position sensor (motor) and current (current sensor. Motor is controlled by four mosfets. Large with micro controller is not direct driving MOSFET gate capacitance, so need to using interfaces in the form of driver IC. For security reasons, the complete machine control system monitoring must be carried out. The motor control system integration on the PCB, usually contains a relay, the relay can be used as the main switch, in the case of a detected fault, disconnect the electrical and electronic control unit.Micro control unit (mu C) must be EPS control system with dc motor. Micro control unit according to the steering wheel torque sensor with the required torque information, forming a current control loop. In order to improve the safety level of system, the micro control unit shall have a board oscillator, so even in the case of external oscillator failure, can guarantee that the performance of the micro control unit, at the same time should also have on watchdog. Of infineon XC886 integrates all of the important micro control components and other safety features can be realized through software, if must perform IEC61508 industry such as safety standards, will have to complete all kinds of diagnosis and introspection task, which will increase the workload of micro control unit. Different customers are using the torque sensor and rotor position sensor varies widely. They adopt different measurement principle, such as resolver, electric magnetic resonance apparatus, based on giant magnetoresistance sensor integration (IGMR).The power level is used to switch the motor current. The power level has two functions: MOSFET drive IC control and protection, MOSFET itself but also responsible for the switch current. MOSFET and partition (such as driver IC and MOSFET with within one or more components) is decided by motor power.Micro control unit of the PWM output port drive current and the voltage is too low, can not connect directly with the MOSFET gate to achieve. Driver ICs role is to provide sufficient current, for the MOSFET gate charge and discharge, the normal switch under the condition of 20 KHZ, at the same time can guarantee high for high and low side MOSFET gate voltage Vgs, ensure low on resistance. If higher lateral mosfets is in open state, the source voltage is close to the battery level. If you want to make the MOSFET to nominal on resistance, gate source voltage should be higher than 8 v. MOSFET completely required for conducting the ideal voltage is 10 v or above, so the grid potential is higher than the battery voltage 10 v. Charge pump is to ensure that the function of the maximum reduce the power consumption of the MOSFET (even if the low battery voltage) under the condition of the circuit. Figure 2 shows, infineon drive IC even under the condition of the 8 v battery voltage, the low high side MOSFET gate voltage is 11 v also can achieve. This will ensure that under the condition of low battery voltage, low power consumption and high system efficiency.Charge pump design of other key features can be according to the requirements of different PWM mode to achieve very low (1%) and high duty ratio (up to 100%). Driver IC is another important function is to detect short circuit condition, avoid damaging MOSFET. Affected by the MOSFET will be closed, diagnosis is submitted to the micro control unit. Current level adjustment can be realized.Most mosfets are normally used in a bridge topology structure, controlled by the driver IC. According to ISO7637 regulation, in the 12 v power grid, the battery voltage is usually up to 16 v. When choosing a MOSFET voltage level, must be produced in the process of recovery for diode induced transient phenomena provide adequate margin of safety (Ls x dl/dt, stray inductance Ls representative, dl/dt on behalf of the switch current slope). Low in dl/dt and low stray inductance in the system, can use 30 v MOSFET, but usually it is best to use 40 v MOSFET, can provide a higher margin of safety. MOSFET technology USES the latest 40 v D2PAK (TO263 package under the condition of 2 mm and 180 a, and the smaller DPAK (TO252) is installed in less than 4 mm and the conditions of the 90 a, can provide very low on resistance, make the EPS system design has the extremely high power density and efficiency 汽车电动助力转向系统概述汽车电动助力转向系统（Electric Power Steering，缩写EPS）是一种直接依靠电机提供辅助扭矩的动力转向系统，与传统的液压助力转向系统HPS（Hydraulic Power Steering）相比，EPS系统具有很多优点。EPS主要由扭矩传感器、车速传感器、电动机、减速机构和电子控制单元（ECU）等组成。发展历史 在汽车的发展历程中，转向系统经历了四个发展阶段： 从最初的机械式转向系统（Manual Steering，简称MS）发展为液压助力转向系统（Hydraulic Power Steering，简称HPS），然后又出现了电控液压助力转向系统（Electro Hydraulic Power Steering，简称EHPS）和电动助力转向系统（Electric Power Steering，简称EPS）。装配机械式转向系统的汽车，在泊车和低速行驶时驾驶员的转向操纵负担过于沉重，为了解决这个问题，美国GM公司在20世纪50年代率先在轿车上采用了液压助力转向系统。但是，液压助力转向系统无法兼顾车辆低速时的转向轻便性和高速时的转向稳定性，因此在1983年日本Koyo公司推出了具备车速感应功能的电控液压助力转向系统。这种新型的转向系统可以随着车速的升高提供逐渐减小的转向助力，但是结构复杂、造价较高，而且无法克服液压系统自身所具有的许多缺点，是一种介于液压助力转向和电动助力转向之间的过渡产品。到了1988年，日本Suzuki公司首先在小型轿车Cervo上配备了Koyo公司研发的转向柱助力式电动助力转向系统；1990年，日本Honda公司也在运动型轿车NSX上采用了自主研发的齿条助力式电动助力转向系统，从此揭开了电动助力转向在汽车上应用的历史。种类及优缺点我们常见的助力转向有机械液压助力、电子液压助力、电动助力三种。机械液压助力机械液压助力是我们最常见的一种助力方式，它诞生于1902年，由英国人Frederick W. Lanchester发明，而最早的商品化应用则推迟到了半个世纪之后，1951年克莱斯勒把成熟的液压转向助力系统应用在了Imperial车系上。由于技术成熟可靠，而且成本低廉，得以被广泛普及。机械液压助力系统的主要组成部分有液压泵、油管、压力流体控制阀、V型传动皮带、储油罐等等。这种助力方式是将一部分发动机动力输出转化成液压泵压力，对转向系统施加辅助作用力，从而使轮胎转向。电子液压助力由于机械液压助力需要大幅消耗发动机动力，所以人们在机械液压助力的基础上进行改进，开发出了更节省能耗的电子液压助力转向系统。 这套系统的转向油泵不再由发动机直接驱动，而是由电动机来驱动，并且在之前的基础上加装了电控系统，使得转向辅助力的大小不光与转向角度有关，还与车速相关。机械结构上增加了液压反应装置和液流分配阀，新增的电控系统包括车速传感器、电磁阀、转向ECU等。电动助力EPS就是英文Electric Power Steering的缩写，即电动助力转向系统。电动助力转向系统是汽车转向系统的发展方向。该系统由电动助力机直接提供转向助力，省去了液压动力转向系统所必需的动力转向油泵、软管、液压油、传送带和装于发动机上的皮带轮，既节省能量，又保护了环境。另外，还具有调整简单、装配灵活以及在多种状况下都能提供转向助力的特点。正是有了这些优点，电动助力转向系统作为一种新的转向技术，将挑战大家都非常熟知的、已具有50多年历史的液压转向系统。驾驶员在操纵方向盘进行转向时，转矩传感器检测到转向盘的转向以及转矩的大小，将电压信号输送到电子控制单元，电子控制单元根据转矩传感器检测到的转矩电压信号、转动方向和车速信号等，向电动机控制器发出指令，使电动机输出相应大小和方向的转向助力转矩，从而产生辅助动力。汽车不转向时，电子控制单元不向电动机控制器发出指令，电动机不工作。优势优点相比传统液压动力转向系统，电动助力转向系统具有以下优点：1、只在转向时电机才提供助力，可以显著降低燃油消耗传统的液压助力转向系统有发动机带动转向油泵，不管转向或者不转向都要消耗发动机部分动力。而电动助力转向系统只是在转向时才由电机提供助力，不转向时不消耗能量。因此，电动助力转向系统可以降低车辆的燃油消耗。与液压助力转向系统对比试验表明：在不转向时，电动助力转向可以降低燃油消耗2.5%；在转向时，可以降低5.5%。2、转向助力大小可以通过软件调整，能够兼顾低速时的转向轻便性和高速时的操纵稳定性，回正性能好。 传统的液压助力转向系统所提供的转向助力大小不能随车速的提高而改变。这样就使得车辆虽然在低速时具有良好的转向轻便性，但是在高速行驶时转向盘太轻，产生转向“发飘”的现象，驾驶员缺少显著的“路感”，降低了高速行驶时的车辆稳定性和驾驶员的安全感。电动助力转向系统提供的助力大小可以通过软件方便的调整。在低速时，电动助力转向系统可以提供较大的转向助力，提供车辆的转向轻便性；随着车速的提高，电动助力转向系统提供的转向助力可以逐渐减小，转向时驾驶员所需提供的转向力将逐渐增大，这样驾驶员就感受到明显的“路感”，提高了车辆稳定性。电动助力转向系统还可以施加一定的附加回正力矩或阻尼力矩，使得低速时转向盘能够精确的回到中间位置，而且可以抑制高速回正过程中转向盘的振荡和超调，兼顾了车辆高、低速时的回正性能。3、结构紧凑，质量轻，生产线装配好，易于维护保养电动助力转向系统取消了液压转向油泵、油缸、液压管路、油罐等部件，而且电机及减速机构可以和转向柱、转向器做成一个整体，使得整个转向系统结构紧凑，质量轻，在生产线上的装配性好，节省装配时间，易于维护保养。4、通过程序的设置，电动助力转向系统容易与不同车型匹配，可以缩短生产和开发的周期。由于电动助力转向系统具有上述多项优点，因此近年来获得了越来越广泛的应用。电动助力转向系统是在机械式转向系统的基础上，加装了电机及减速机构、转矩转角传感器、车速传感器和ECU电控单元而成。产品特点液压助力转向系统已发展了半个多世纪，其技术已相当成熟。但随着汽车微电子技术的发展，对汽车节能性和环保性要求不断提高，该系统存在的耗能、对环境可能造成的污染等固有不足已越来越明显，不能完全满足时代发展的要求。电动助力转向系统将最新的电力电子技术和高性能的电机控制技术应用于汽车转向系统，能显著改善汽车动态性能和静态性能、提高行驶中驾驶员的舒适性和安全性、减少环境的污染等。因此，该系统一经提出，就受到许多大汽车公司的重视，并进行开发和研究，未来的转向系统中电动助力转向将成为转向系统主流，与其它转向系统相比，该系统突出的优势体现在： 一、降低了燃油消耗。液压动力转向系统需要发动机带动液压油泵，使液压油不停地流动，浪费了部分能量。相反电动助力转向系统（EPS）仅在需要转向操作时才需要电机提供的能量，该能量可以来自蓄电池，也可来自发动机。而且,能量的消耗与转向盘的转向及当前的车速有关。当转向盘不转向时，电机不工作，需要转向时，电机在控制模块的作用下开始工作,输出相应大小及方向的转矩以产生助动转向力矩，而且，该系统在汽车原地转向时输出最大转向力矩，随着汽车速度的改变，输出的力矩也跟随改变。该系统真正实现了按需供能，是真正的按需供能型（on-demand）系统。汽车在较冷的冬季起动时，传统的液压系统反应缓慢，直至液压油预热后才能正常工作。由于电动助力转向系统设计时不依赖于发动机而且没有液压油管，对冷天气不敏感，系统即使在-40时也能工作，所以提供了快速的冷起动。由于该系统没有起动时的预热，节省了能量。不使用液压泵，避免了发动机的寄生能量损失，提高了燃油经济性，装有电动助力转向系统的车辆和装有液压助力转向系统的车辆对比实验表明，在不转向情况下，装有电动助力转向系统的国辆燃油消耗降低2.5%，在使用转向情况下，燃油消耗降低了5.5%。 二、增强了转向跟随性。在电动助力转向系统中，电动助力机与助力机构直接相连可以使其能量直接用于车轮的转向。该系统利用惯性减振器的作用，使车轮的反转和转向前轮摆振大大减水。因此转向系统的抗扰动能力大大增强和液压助力转向系统相比，旋转力矩产生于电机，没有液压助力系统的转向迟滞效应，增强了转向车轮对转向盘的跟随性能。 三、改善了转向回正特性。直到今天，动力转向系统性能的发展已经到了极限,电动助力转向系统的回正特性改变了这一切。当驾驶员使转向盘转动一角度后松开时，该系统能够自动调整使车轮回到正中。该系统还可以让工程师们利用软件在最大限度内调整设计参数以获得最佳的回正特性。从最低车速到最高车速，可得到一簇回正特性曲线。通过灵活的软件编程，容易得到电机在不同车速及不同车况下的转矩特性，这种转矩特性使得该系统能显著地提高转向能力，提供了与车辆动态性能相机匹配的转向回正特性。而在传统的液压控制系统中，要改善这种特性必须改造底盘的机械结构，实现起来有一定困难。四、提高了操纵稳定性。通过对汽车在高速行驶时
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