机械毕业设计英文外文翻译468四轮转向汽车的转向特性及控制技术

附录

附录A

Steering Behavior and Control Technology

0f Four—wheel Steering AutomobiIe

ABSTRACT

This paper analyses the characteristics of car four-wheel steering control to, summarizes the principle of construction four-wheel steering cars. Introduced the four-wheel steering system control strategy. Points out the four-wheel steering system control technology faces difficulties, and prospects the trend of its development.

Keywords: four-wheel steering; Steering characteristics; Working principle; Control; Development;

1. Introduction

With modern road traffic system and the development of modern automobile technology, people on the car's steering control performance and driving stability requirement is increasing day by day. As the most effective improve vehicle handling performance of a kind of active chassis control technology - four-wheel steering technology. In the 1980s began in cars get application, and as the modern automobile industry and continuous development. Car four-wheel steering means in turn, the rear car can be relative to body active steering, that the car can be up to four wheels role. To improve the car turned to maneuverability, handling stability and driving safety.

2. The car's steering four-wheel steering

2.1 4ws cars and 2ws steering process analysis

Ordinary two wheel steering can not only the front car around its own wheel rotation and relative to body deflection around the precision, then wheel rotation and not only deflection. When the driver turned the steering wheel, front wheel steering, changed directions face front tyre, produced a transverse force, through the front wheel effect on body, make the body yawing and produce centrifugal force, the rear wheels cornering,

produced change direction, participate in the sports car to. And the rear and front car 4ws as, can rotation can also deflection. When the driver turned the steering wheel, front and rear wheels, that car almost at the same time to change direction, realize steering movement.

In turn, the 2ws car before active steering wheel rotation just makes passive steering. Obviously, 2ws cars in steering process from the steering wheel rotation to rear wheel steering movement in between the existence of certain lag time. This phase lag 2ws automobile steering characteristics make the servo sex becomes poor, and that the car steering radius increased. In addition, 2ws car at a high speed, the steering wheel Angle relative to certain incremental, body yaw-rate and lateral acceleration incremental increases, made the car at a high speed handling and stability becomes poor. And in turn, the car 4ws has done before, rear wheel steering, active in the process of steering, high sensitivity, fast response, effectively overcome the shortcomings.

2.2 4ws automobile steering way

According to the theory analysis and road test showed that a four-wheel steering can improve the maneuverability and steering control stability of high speed, modern 4ws car is developed according to the guiding ideology. Generally speaking, in the process of steering cars in 4ws, according to different driving conditions, front and rear wheel steering Angle should follow certain rules between. At present, the front, rear typical 4ws deflection rules generally are described below:

(a) inverse phase steering

As shown in figure A1 (a) shows, steering wheel Angle at low speeds or larger, front and rear inverse phase shift, realize that the rear wheels with the front deflect deflect instead, and with the steering wheel Angle deflection Angle increases and increases in a certain range. This redirection speed way can improve the manipulation of the car, reduce automobile portability turning radius, making cars maneuverability. Easy car turned turn, obstacle avoidance and driving, garage and parking. As for cars, if rear inverse phase 5 °, then turned can reduce minimum steering radius was about 0.5.

(b) phase with steering

As shown in figure A1 (b) shows, in a high-speed or steering wheel Angle is lesser, front and rear wheels with phase shift, realize that the rear wheels deflect the deflection direction with front wheel. Make the car body yaw-rate greatly reduce automobile body, can reduce the tendency of cornering undergo dynamic, guarantee the overtaking the highway, elevated highway, in and out, in the approach and flyovers insufficient steering state. Now, there are many 4ws cars take improving vehicle handling performance focuses on making cars on high-speed steering stability, without excessive demands in low-speed driving car course-altering maneuvers flexibility. The features is low by front wheel steering car only when only in car speeds, after up to a certain value, rear, only participate in steering phase