The Overview of Active Front Steering System and the Principle of Changeable Transmission Ratio

Active front steering system is a new technology, This technology developed by German BMW Company and ZF Company, And this system has been equipped to parts of BMW 3 and BMW 5. Because this technology is still mechanical connection purely, it inherited and developed the traditional steering system completely, and also it got rid of many restrictions which belong to the traditional steering system. It is an important innovation for automotive steering system. This paper introduces the composition, The function and the principle of the system in detail, Then based on this, it analyses the dual planetary gears which is the key components of the system, In the end, this paper gives the principle of the changeable transmission ratio.