The Purpose and Significance of Design

The electric power steering system is directly assisted by the electric booster, eliminating the power steering pump, hose and other necessary hydraulic power steering system devices, not only conducive to energy saving but also to protecting the environment. In addition, it has the characteristics of simple adjustment, flexible assembly and the ability to provide steering power in a variety of conditions. When the driver is operating the steering wheel for steering, the torque sensor detects the steering of the steering disk and the size of the torque, it then transports the voltage signal to the electronic control unit, and the electronic control unit issues instructions to the motor controller based on the torque voltage signal, rotation direction and speed signal detected by the torque sensor so that the motor output of the corresponding size and direction of the steering force torque, resulting in auxiliary power. When the car does not turn, the electronic control unit does not issue instructions to the motor controller, consequently the motor does not work. [1]

(1) Foreign countries: in the 1980s, Japan Suzuki Company for the first time developed an

electric power steering system, after which Japan's Dafa Automobile Company, Mitsubishi Motors and Honda Motor Company have developed EPS suitable for their respective models. Japan Seiko had became the world's largest EPS production plant, accounting for 30% of the Global, Japan Guangyang and had reached 8 million sets in 2006, Japan Toyota since 2003 began mass production of P-EPS, the annual output had been 1 million sets, the United States Delphi Company, TRW Company had successfully developed EPS system which greatly promoted the development of EPS technology. After nearly 20 years of development, EPS technology is becoming increasingly perfect, its application range from the initial micro-car supporting to the load of large-scale high-end car supporting development. Foreign production of low-grade small, micro-car mostly equipped with electric power steering gear have been used in some mid-range cars and luxury cars. The use of

medium-sized vehicles and heavy vehicles are also in the research stage.

(2) Domestic: in 2006, domestic automobile production and sales was more than 5 million, the current domestic development of EPS mainly for 1.6 of the small and medium-sized cars below the displacement, and 1.6 of the vehicles below the vehicle accounted for about 70, so the market potential is huge. At present, the actual installation of EPS car has reached 15%, mainly Changhe Big Dipper, Hafei Bao Road and so on. The development of EPS manufacturers and research institutes have a good dozens of them, but because EPS for the mechatronics of high-tech products, traditional automotive steering gear manufacturers lack of controller development of electronic experts, and research institutes focus on theoretical research, lack of practical experience and mass production of the ability to build lines, so EPS development progress is slow. EPS is the development trend of passenger car power steering system, and is gradually applied to medium and heavy vehicles. In the process of design and development, test bench testing is an important stage, so the design of EPS experimental bench also plays an important role. In the above background, this paper will design EPS mechanical system and test bench, which will provide the foundation and platform for the development and testing of EPS control system. [2]

Electric power steering system not only has the advantages of light steering and convenient steering of hydraulic power steering system, but also has many advantages such as saving energy and protecting the environment. The emergence of electric power steering system is an inevitable result and has obtained huge market demand. [6] The basic requirements of the electric power steering system was introduced, and the assembly design and related parts design of the electric power steering system for passenger cars was carried out. Finally, the validation has been carried out through experiments. [3]

Therefore, replacing EPS with hydraulic power steering system is the inevitable trend of steering system development. [4] There are some problems in software matching and adjustment of electric power steering system, such as non-linearity of hand force, poor sense of middle and high speed position and steering wheel correction. By adjusting the assisting curve and adjusting the stiffness of steering system, the fluctuation of in-situ moment is reduced, the sense of middle position is enhanced, the linear sense of force is established and the steering wheel is corrected. It provides a reference direction for the subsequent development of electronic power steering system software calibration. [5]

2. 研究的基本内容与方案

Basic Content, Objectives, Technical Solutions and