Study Of Principle, Kinematics And Dynamics Of The Globle-coupling Torsion-elimination Suspension System

For those high off-road vehicles that mostly run on specially rugged and complex road, the uneven wheel loads caused by the uneven ground input will cause the torsion of body or frame and lead to the early fatigue wreck of vehicles' parts,even the rupture of the body. At the same time,when the unevenness of wheel loads becomes serious,the wheel will trend to be impending from the road and damage the adhesion performance and influence the right drive and steering ability of the vehicle,thus the vehicles' cross-country performance becomes worse. So it is undoubtedly very important to develop a new suspension system to eliminate the torsion load of off-road vehicle.According to the thought of"torsion-elimination suspension"brought forward by Prof. Guo Kong-hui,an academician of the Chinese academy,a new torsion-elimination mechanism suitable for the front torsion spring and rear leaf spring suspension was designed on a homemade SUV vehicle. It wholly couples the four wheel suspension to improve the evenness of vertical wheel loads and reduce the torsion loads and dynamic load of the body and improve the wheel ground adhesion under roughness impact. The essential that the torsion-elimination suspension is another kind of"Active Suspension"of which stiffness is alterable was revealed by establishing the physical and dynamics functions.Basing on the multi-body dynamics theory,the multi-body dynamics models of original vehicle and vehicle with torsion-elimination suspension under ADAMS/View environment were established. The application effect of torsion-elimination suspension was simulated and analyzed on three typical roads,the longitudinal lean,lateral lean and twisting roads. The research results proved that the torsion-elimination suspension could effectively even the wheel loads and reduce the twist load of the frame and improve the ground adhesion. Furthermore,the ride comfort simulating tests under the pulse input and random input were carried out for the established models,indicating that the ride comfort performance of vehicle with torsion-elimination suspension was the same as that of original vehicle under single-bump pulse input and high frequency and small amplitude road excitation. In addition, the handling stability simulating tests of these two kinds of vehicles were done and the results indicated that the vehicle with torsion-elimination suspension behaved more insufficient steering characteristics than the original vehicle at high speed in the steady static circular test, and other handling stability parameters were the same as that of the original vehicle except that the roll angle,yaw angular velocity and lateral acceleration of the vehicle were slightly smaller than those of the original vehicle in the steady static circular test,steering transient response test and single-lane test,indicating that torsion-elimination mechanism would not bring adverse effects to the handling stability of vehicle.A wheel loads dynamic testing system base on the ARM9 processor and Linux operation system was developed,with which the dynamic wheel vertical loads of the original vehicle and vehicle with torsion-elimination suspension were tested in the case of single bump and twist roads. The testing results indicated that the vehicle with torsion-elimination suspension could effectively reduce the unevenness of wheel loads and twist load of the frame and improve the wheel ground adhesion. The testing results and simulation results are relatively the same,proving that the simulating models is right.Basing on the suspension K&C testing bed,the synclastic wheel jump test,reverse wheel jump,longitudinal force test,lateral force test and returnable torque test were applied to two kinds of vehicles. The testing results indicated that the vehicle with torsion-elimination suspension almost had the same handling stability as the original vehicle except for larger longitudinal flexibility than that of original vehicle. In some given load cases,the change of some handling stability characteristic parameters such as toe angle, camber angle,unilateral wheel track and rolling angular stiffness, etc were advantageous for the enhancement of handling stability of vehicle. In addition,the vertical wheel stiffness of the vehicle with torsion-elimination suspension increased with respect to that of the original vehicle,leading to the improvement on the evenness of wheel loads and torsion-elimination effect while the vehicle suffers uneven ground input.