Design And Dynamics Analysis Of Rectilinear Independent Suspensions And Steering System

Suspension is an important component of vehicle chassis. Its performance has direct impact on the vehicle's handling stability and riding comfort. Independent suspensions are widely used in the morden cars, accompanying by the rack and pinion steering and the trapezoidal transmission linkages. However, due to the limitations of the guidance mechanisms, the commonly used independent suspensions cannot guarantee the wheel alignment parameters unchanged while the wheel jounces and rebounds. In addition, the steering system cannot always provide steering wheels with precise and correct turning angles and can not reduce the turning interference on suspension movement. Therefore, it is very difficult for them to help to improve the vehicle's handling stability and riding comfort.This research was funded by the National Natural Science Foundation of China,"The innovative design theory of independent suspensions and its application research in vehicles"(No.50805083). Aiming at the problems in current suspensions and steering systems, this thesis investigated a new type of rectilinear guidance mechanism and its applications in front and rear independent suspensions. Correspondingly, the steering system which mactches the front suspension was synthesized, and the kinematics and dynamics were also carried out. This thesis mainly accomplished the following research work:1. Studied a linear rigid body guidance spatial mechanism, and analyzed its principle of mechanism and kinematics. Designed the front and rear independent suspensions in line with the primary requirements of independent suspensions. The analysis results fundamentally show: this spatial guidance mechanism has a large range of motion, and it allows the wheel alignment parameters to be unchanged in theory while the wheel jounces and rebounds.2. Based on the spatial guidance mechanism, the front and rear independent suspensions are developed. The rigid body and elastic kinematics are simulated at computer. Besides, comparative discussions among the front and rear suspensions commonly used are also conducted to further demonstrate its kinematic advantages. The result shows that the linear guidance independent suspension can ensure the main kinematic character parameters to change within a smaller range during the wheels'jumping up and down. This surely leads to the improvements of hangdling stability and riding comfort.3. Two kinds of steering systems which match with the rectilinear motions of the suspension are developed. The two steering gears are based on non-circular gearing theory and corresponding to the rotation and swing transmission mechanisms. The steering simulations and theoretical analysis are carried out. The results demonstrate that: the non-circular steering system can ensure the steering wheels to take a correct turning and its transmission mechanism doesnot induce steering angle while the wheels are jumping up and down.4. Vehicle system dynamics simulations of the linear guidance independent suspensions and the corresponding steering system are excuted at computer. Typical operating tests on ADAMS indicate that the linear guidance suspensions can improve steady-state and transient response performance, which therefore enhances the vehicle's handling and stability.