Vehicle wheel suspension with transverse leaf spring and mounts providing a high roll ratio

Abstract

A vehicle wheel suspension has a composite, transversely oriented, leaf spring which is vertically thick and stiff in end regions extending inward from each end of the spring past the vehicle body support area but is vertically thin and compliant in a middle region between the end regions. The spring is constructed of a long, longitudinally aligned fiber and resin composite which is split at each outer end of the middle region into upper and lower horizontal layers separated by a core having a tapered inner end and extending through the end region. The inserts provide the additional vertical thickness in the end regions without widening the middle region and may be made of a different material, such as a short, randomly oriented fiber and resin composite. The spring thus flexes easily in the heave mode, in which the thin middle region of the spring flexes vertically in opposition to each end. But the center of the spring resists flexing in the roll mode, in which the ends of the spring move vertically in opposition to each other and the spring attempts to flex in the thick end regions. The spring thus provides a high spring rate in roll with a low spring rate in heave for a high roll ratio. The flexing of the spring in the middle, and thus the roll ratio, is additionally enhanced by providing pivoting and longitudinally translating body mounts for the spring. Two specific mount structures are described: a hybrid mount in which mount members above and below the spring each comprise a high modulus member with a rounded surface adjacent the spring affixed to a low modulus member providing longitudinal compliance, and a link mount providing pairs of fore and aft links pivoted at both the spring and body ends.