The Dynamic Steering Characteristics Analysis Of Heavy Truck With Double-front-axle Steering System

In recent years, the share of heavy haul transportation is growing rapidly in road transportation. To meet the domestic commands, a lot of motor corporations have increased the investment and development on heavy duty commercial vehicles. A better performance of heavy duty commercial vehicles is in desperate needed. Heavy commercial vehicles are designed in the direction of heavy load. In order to meet the demands of current traffic laws and regulations, more axles added to the commercial vehicles is a good resolution. However, the increase of axles put forward new requirements for the performance of vehicles, especially the steering performance. As an advanced steering system, the double front steering system has been widely used on commercial vehicles with 4 or 5 axles. As a fact, there still exist a lot of problems in the use of these vehicles, such as the serious wear of tire, poor steering mobility and poor manipulation stability.This paper analyzed the form of the double-front steering system and the kinematic theory of Double-front Axle Vehicles. Besides, the mathematical model of the steering mechanism, the basis of optimization research, was built by making the steering mechanism reduced to the plane mechanism. With the mathematical model, this paper analyzed the influence that different parameters of steering mechanism have on the steering angles of wheels. Then, this paper introduced a mathematical model to make quantitative analysis for the wear of tires. With this model, the influence of cornering and wheel alignment on the wear of tire could be attained. For Double-Front Axle Vehicles, its Ackermann error is the main cause of serious tire wear. The wear of tires caused by Ackerman error was calculated by transforming the errors into slip angles. Based on the kinematics theory of Double-front Axle Vehicles, a new kind of Ackerman steering model on the basis of concerning behavior of tire had been proposed. With the model, the relationship between the slip angle of wheel and the steering angle of wheel controlled by steering mechanism can be obtained. Then, the model was solved with the dynamic simulation software. The relationship between the deflection wheels was obtained. Combined with the mathematical model and optimization algorithm, the steering trapezoidal mechanism and double rocker arm mechanism was optimized. Results show that the optimized steering mechanism can make the relationships of deflection angles of wheels be more reasonable. The angles are more close to the idealized means and the Ackerman error decreases, effectively reducing the wear of tires.