On the Structural Simplification, Compact and Light Design of a Vehicle Suspension, Achieved by Using a Colloidal Cylinder with a Dual Function of Absorber and Compression-Spring

Abstract

Classical suspension (oil damper mounted in parallel with compression helical spring) is replaced by a colloidal suspension, in which case the spring can be omitted. Hence, structural simplification, accompanied by a compact and lighter design can be achieved. Oil is replaced by an ecological mixture of water and water-repellent nanoporous particles of silica (artificial sand). Travel tests using a V8 4.3L auto vehicle equipped with classical and colloidal suspensions were performed. Ride comfort (ISO 2631 method) was evaluated during travel (speed: 5–40 km/h) on a normal road with an asphalt step (height: 37 mm; width: 405 mm), for various values of the tire inflation pressure (150–250 kPa). On normal road without step the travel speed was increased up to 80 km/h. Acceleration at seat, seat-back, and feet surfaces was processed using the commercially available DEICY system for ride comfort evaluation. Spring omission, accompanied by 60 % reduction of the outer diameter, and 30 % reduction of the mass was achieved both for the frontal and rear colloidal suspensions. Results concerning the ride comfort were validated in the case of classical suspensions. Relationship between the travel speed of the vehicle and level of vibration perception was obtained for various values of the tire inflation pressure. Ride comfort decreased at augmentation of the travel speed and the tire inflation pressure. Since the colloidal spring constant was 6 times larger than the constant of the compression helical spring, colloidal suspension provided 1 rank lower ride comfort than the classical suspension. Pitching and rolling movements were not considered during the estimation of the ride comfort. Relation between the lateral acceleration and the rolling attitude angle was experimentally determined. Ride comfort results were explained by taking into account the vehicle behaviour during frontal, rear and superimposed impact excitations, in correlation with the variation against travel speed of the frequency weighting proposed by the ISO 2631. Although the colloidal suspension was found to provide inferior ride comfort than the classical suspension, results obtained so far are encouraging since better performances are to be expected by softening the colloidal spring, and by redesigning the suspension including the stabilizers.

F2012-G01-006