That is, when variable steering ratio is adjusted according to the vehicle speed and the steering angle of the steering gear ratio, when the car is parked starts, a lower vehicle speed or the steering angle is large, the steering gear ratio to provide a smaller; and when the car at high speed or steering angle is small, to provide a large steering gear ratio, thereby improving the steering stability.
1. The variable ratio steering noun interpretation
to adjust the variable steering i.e. the steering gear ratio according to the vehicle speed and the steering angle, when the car is parked starts, the vehicle speed lower than or when the steering angle is large, the steering gear ratio to provide a smaller; and when the car at high speed or steering angle is small, to provide a large steering gear ratio, thereby improving the steering stability.
2. Classification variable steering ratio
is called by different manufacturers of such systems are manifold, such as BMW called active steering system AFS (Active Front Steering,), which is referred to Audi dynamic steering system (Audi dynAMIc steering), Lexus / Toyota used is variable gear ratio steering system VGRS (variable gear ratio steering), and the variable steering ratio Benz system uses a “direct steering system” name. Although similar functionality, but the technology they use is very different.
3. The variable ratio steering works
The variable gear ratio steering at the technical level is not a level of the system, there are mainly two ways to achieve this function A way is to rely on a special rack to achieve, the principle is simple, the cost is relatively low, not high technology content, while the other is more complex, is achieved through the planetary gear mechanism and electronic systems.
4. The variable steering ratio of the mechanical system
It is mainly an issue in the “rack and pinion” and “rack”, by special processing gap unequal pitch rack, so that when the steering wheel, and the gear pitch is not equal to the rack gear, will change the steering ratio, the left and right sides of the teeth from the intermediate position denser the rack within this range less displacement amplitude at small steering (for example, a slight adjustment change line direction), the vehicle will become calm, while the distal end sides of the rack tooth pitch less dense, within this range, the steering wheel is rotated, relative to the rack of displacement becomes large, so when the steering substantial (e.g., parking, turn, etc.), the wheel will become more flexible. In addition to this technical process requirements more stringent rack, and not many “high tech” in which the gear ratio drawback is the limited range and can not be flexible and change, and the advantage is obvious – completely mechanical structure high reliability, durability, structure is very simple.
5. The electronic variable ratio steering system
high technology content, compared to the variable steering ratio of the mechanical systems, electronic variable steering using a more complex structure than the mechanical system and the need to use in conjunction with an electronic system. Can better achieve “low-speed light sensitive, high-speed steady heavy” demand convenience and stability it brings the vehicle is traveling are ordinary variable power steering system and a simple “mechanical” Variable Gear Ratio steering can not match.