Concepção geométrica e análise cinemática de sistema de esterçamento do eixo traseiro em função da rolagem de carroceria para veículos de quatro rodas

Abstract

The work demonstrates the operation of a system capable of steering the rear wheels of a vehicle during curved movements by utilizing body roll, without causing directional variations in the rear axle wheels when encountering symmetrical irregularities on both sides during straight paths. To achieve this goal, the traditional vehicle model is presented, which lacks rear axle steering and keeps the directions of the rear wheels parallel to the longitudinal axis of the vehicle throughout the vertical range of suspension. Subsequently, a vehicle model with the ability to steer the rear wheels based on body roll, using suspension geometry, is introduced, highlighting the advantages over the traditional model. Furthermore, a novel mechanism is proposed to steer the rear wheels based on body roll in a four-wheeled vehicle. This mechanism ensures that the rear wheels remain parallel to the longitudinal axis when both sides of the rear suspension are symmetrically compressed or extended during straight paths. Following the development of each vehicle model, four tests are conducted. The first test examines the variation in wheel direction throughout the vertical suspension travel of the rear axle in a vehicle without rear wheel steering capability. The second test replicates the procedures of the first test, but in a vehicle equipped with rear wheel steering through body roll using a fixed suspension geometry. The third test is performed after implementing the proposed new mechanism, evaluating the inclinations of both rear wheels during vertical suspension travel when both sides are symmetrically compressed or extended. Lastly, the fourth test describes the directions of the rear wheels in a situation where one side of the rear suspension is compressed while the other is extended, simulating the body roll that occurs during curves. The results demonstrate the effectiveness of the new mechanism in reducing the vehicle's turning radius without compromising stability when traversing symmetrical irregularities during straight paths.