【正文】 ontrol by electromagnetic valve with liquid flow speed changing, and change the size of the moment, make grants to individual driver according to speed and driving conditions, changes to manipulate portability and stability to harmony. But at the same time, ECHPS also exist because of oil pump continuous work caused by excess energy consumption, the hydraulic system occupies a large space, easy to leak, noise big shortings, and increased its speed detection control device. And the control valve of structure than HPS plex and cost is higher, which are mainly applied in limousines and sports by using the car. electric hydraulic steering system Electric hydraulic steering system (EHPS) is in hydraulic steering system developed on the basis of. Its characteristic is driven by the engine turns ZhuLiBeng shifted the hydraulic motor drive, and increased its speed sensor, steering angular velocity sensor and steering control unit etc electricals. The system of hydraulic oil tank, oil pump, motors and steering control unit has integrated in motor oil pump in the group. Work steering control unit according to car of the speed and steering Angle calculated as the input signal output signal, control ideal appropriate power, motor output ZhuLiBeng driven hydraulic work. Through the hydraulic oil for steering gear provide power [3]. When the automobile lowspeed road, steering control unit control motor output large torque, make drivers can easily turned the steering wheel。t work. Electric power steering system can realtime in different speed for car turned to provide different under the instrumentality of guarantee in lowspeed driving car deft and agile, high speed is stable and reliable. Electric power steering system generally consists of mechanical parts and controlling part. Mechanical parts mainly include transmission unit (the clutch, the steering assembly) and execution unit (electrical), etc. Control part mainly according to sensors to speed and torque signal for puting, drive motor control instructions issued to provide power for steering. EPS pared with HPS, except to save energy outside, due to the elimination of the hydraulic system and improve the environmental performance, solves the malpractices of hydraulic drive brings. The system is made of manufacturers to provide to the vehicle manufacturer, can be directly mounted. Under different conditions of different models, and different for different drivers steering properties, through software modification, convenient and quick. Complete EPS system also includes fault diagnosis and safety protection system. When malfunction happened, could stop booster, automatic recovery to manually control mode and warning signal, and show the memory of abnormal content such as torque sensor itself anomalies, and motor speed sensor abnormal work abnormal, battery abnormal etc [5]. Electric power steering system has bee the vehicle steering system technology development, but the system of mainstream has its limitations, because motor power steering and provide power is limited, if the body is heavier, steering system needs to have larger drive power, electric power steering system is ragged. So the system more for small cars, has lots of equipment to senior cars, and gradually to regular cars and small mercial vehicle development. wire control power steering system With power Steering technology development, the Wire control power Steering system (Steering By Wire, abbreviation SBW) is as automobile electronic technology development and grows the latest achievements of a brandnew Steering system. It through the wire transfer signals, control actuator action to replace traditional steering system of mechanical transmission and mechanical connection from the main controller, help torque in corresponding parameters, after decoding to turn his orders, by executive motor steering motor provides. SBW cancelled and steering wheel steering plate between mechanical connection device, now the steering wheel module, steering executive module and the main controller ECU, three main parts and automatic protection fault systems, power auxiliary module. It is made up of a realtime bus structure (for example, FlexRay HTTP or CAN) connected to the equipment [6]. Can easily and other system integration, unified coordination control. System work, sensor test driver39。 (3) fort enhancement。 6 the driver went leg activity space increases, more convenient. Shipturning plate and the steering without mechanical connection between, generating let pilot able to perceive cars driving condition and actual road conditions lk feeling is more difficult, so current power steering system wire used only for some concept car. Has not conducted batch production and installation, its reliability and cost is the main cause of blocking its development. Mainly displays in if micro controller appears problem, steering system will pletely failure, it is not like electric power steering system and electric hydraulic steering system and hydraulic steering system, in motor or hydraulic system problems, still can take the human to control the car [9]. The system of micro controller if malfunction, because no mechanical system is connected the steering wheel and steering gear, so it could not control cars to turn around. for wire control power steering system outlook Although wire control power steering system now not satisfactory, but SBW still clear is car development direction. SBW system eliminates mechanical connection between the design of steering wheel, tyre will be greatly simplified. Not only improve the design efficiency, but also improve the economy, and car improve overall safety. SBW system work mainly by the electronic ponents to assume. The application of electronic ponents marks a considerable amount of mechanical parts reductions, and steering system the size and weight of ease. The whole process of steering by electronic device to achieve, which gre