附 录A 外文文献
Overview ofDevelopment on Vehicle EPS System Abstract
The currentdevelopment of an electric power steering(EPS) system in an automobile is explicated. The structure, types and characteristics of electric power steering system are introduced. The modeling technologies for electric power steering system and control strategies are analyzed and compared. The development trend of electric power steering system in an automobile is also discussed. It is pointed that the electric power steering technology is one orientation ofpower steering technologies in the future, and whichwill occupy a predominantposition in power steering field.
Key words:Automobile; Electric power steering system; Development trend
1 EPS system types and characteristics 1.1 EPS system classification
The early development of EPS system is low in steering type car。Present 4 types of EPS system are based on rack-and pinion steering system,The installation position according to power motors can be divided into different:Type booster steering、Small gear power type、Double small gear power type and Rack power type。The steering the
instrumentality of motor power type EPS installed in the steering,Motor power torque through increased after worm worm gear deceleration in the steering directly added twist。Its advantage is motor can be installed in any position hacking,Relative to other several types minimum cost;The drawback to motor torque ripple effects of driver feel bigger。The drawback to motor torque ripple effects of driver feel bigger,The instrumentality of torque motor added in small gear axle directly。Advantage: rigid, steering road to feel strong。Double pinion steering rack boosts type EPS are installed on two small gear, A small gear and steering plate connected, power motors through another pinion and rack meshing, provide power for rack. Advantage: can provide relatively large pow.
1.2 EPS system merit
EPS system and the traditional hydraulic power steering system has the following advantages compared
（1)EPS in various riding condition can provides the best efforts。In the car or parking at Treasury and low-speed steering provide enough power for the driver，In high-speed steering made drivers have good road feeling，And reduce caused by pavement of rough disturbance of steering system，Improving auto steering characteristics。
（2）Improve the car fuel economy，Urban conditions can improve fuel economy. (3) the average 5%, saving fuel 3. EPS system only when
the vehicle steering only provide power, Unlike traditional hydraulic power steering system even in don't turn,Pumps have been running.
（3）EPS system structure is compact, parts, convenient in installation and smaller number to assemble, enhanced the labor productivity due to tell the packed in engine pulleys and oil pump, set aside of the space can be used to install other parts of FIAT Punto production company adopted DELPHI company developed the electric power steering system, loading time reduced around 80 percent.
（4）EPS system cancelled hydraulic loop, there is no oil leakage and oil leakage problem, reduce the pollution to the environment, and save a lot of steering oil.
（5）EPS system has the function of self diagnosis, convenient in maintenance and maintenance.
（6） EPS system has good low temperature performance, even in 40 environment, EPS system also can work very well, has higher reliability and safety.
（7） EPS system's biggest advantage is the performance of the whole system can not changing the system structure of the cases, by changing the system control strategy of programming realize, in order to meet different models and different driving feel the need, greatly reduced the development cost and improve the efficiency of development.
2 EPS System Key Components
EPS system key components Angle sensor are mainly torque sensor speed preach
2.1 Corner Sorque Sensor
Sensors for real-time detection of steering Angle rotation direction and steering disk disk position，The torque sensor for real-time detection steering dish torque size，And will signal transmission to EPS system of electronic control unit (ECU)。Corner the torque sensor precision problem decided the electric power steering system performance and reliability，Accelerate development research performance reliable, low-cost corner torque sensor is very important，The cost of the sensor is restricted by the electric power steering system one of the main factors market. 2.2 Speed Sensor
The wheel speed sensors used to measure the size of the average speed speed sensor using electromagnetic induction sensor installation on the sensor in gearbox according to the change, the main speed pulse vice two system signals to ECU, because this was two system, therefore the signal reliability improved 2.3 Power Motors
Power motors is EPS system actuators, and help motor characteristics directly affect the EPS system to control the ease or
drivers handle EPS system for power motors are basic requirements of the high reliability should be, big power, low noise and vibration, low friction torque, small volume and weight; Can turn in blocking next output torque; good mechanical properties, in the process of operation, as far as possible to small torque ripple; The small inertia should as far as possible; Should be able to fast reverse current EPS system the instrumentality of permanent magnet dc motor are usually motive brushless dc motor and switched reluctance motor dc have brush motor mature technology, controller, low cost, but simple existing wear easily power dense brush Spark, need not often maintenance and high efficiency and power density under。Therefore, suitable for the development of the EPS systems used low cost high power density of brushless dc motor is the future research direction of electric motor booster. 2.4 Reducing Gear
Its and motor is linked together, up slow increase twist of the deceleration agencies role EPS system often adopted worm and worm wheel mechanism circulating ball screw nut planetary gear agencies to ensure that EPS system only in a predetermined speed range role, some EPS system also with clutch when speed up to a certain value, clutch, motor stopped working, steering system. 2.5 Electric Power Steering