Abstract
McPherson independent suspension is one of the widely utilized suspension types of the modern vehicle. Especially for the FF minibuses and sedans. It has merits such as simple structure, small unsprung mass, easily arrange engine and steering system, suited for many types spring and realize vehicle highness auto adjust etc. Furthermore cause the kingpin axes is the connecting line between the hinge of upper absorber and vehicle body and the hinge of transverse arm and knuckle, when the wheel fluctuating, the lower absorber moved with transverse arm, so the kingpin axes angle is changing, i.e. the wheel is moving along swinging kingpin axes. Hence when the suspension deformed, it changes kingpin orientation angles and tread. So if properly adjust the arrange of struts and links, the wheel orientation parameters will change lesser.
During the practical operation, one minibus has excess tire wear and heavy steering effort. They serious affect the vehicles steering stability and operation performance. Theoretically analysis indicates the reason for the above phenomena is unreasonable frontal wheel orientation parameters and their changing laws with tire fluctuating, which are decided by the unreasonable structure parameters of frontal suspension and steering system.
Based on the Multi-Body Dynamic theory, this paper established dynamic model of the frontal suspension and steering system. Utilized Sensitivity Analysis Method, it gained each frontal orientation parameters sensitivity vs. structure parameters. Then took the largish effect structure parameter as variable and the frontal orientation parameters as goal, this paper made optimum design of the frontal suspension and steering system, calculated the changing law curves of camber, inclination, caster, tread fluctuant quantity and toe in fluctuant quantity vs. tire fluctuating. Furthermore it also redesigned the key components such as knuckle and transverse arm. Through the test-rig and road test, the results showed the modified system overcame the above problems.