Proposal of a method to determine shock absorber conditions on a motor vehicle

Abstract

Suspension condition has a direct influence on the behavior of brakes, direction, stability, etc., on a motor vehicle and right operation of the car depends directly on the fatigue suffered gradually during the service life. Nowadays, there is no evidence of any regulation testing the suspension system in the homologation process of a vehicle. Inspection and verification of vehicle suspension conditions is carried out by Periodic Motor Vehicle Inspections (PMVI's). The aim is to determine the suspension system performance. It is not possible to remove parts of the vehicle and the inspection must be rapid and reliable. Currently, there are suspension benches whose results and rejection criteria are not suitable. This has been already demonstrated by several authors as Dr. Velasco (Criterio de inspeccíon en bancos de ensayo del sistema de suspensíon de un veh́iculo autoḿovil. Tesis doctoral, Universidad Carlos III de Madrid, 1997) and Dr. Calvo (Determinacíon de un criterio de inspeccíon para verificar el comportamiento dińamico del sistema de suspensíon de un veh́iculo autoḿovil. Tesis doctoral, Universidad Carlos III de Madrid, 2003). With the current methods of inspection, test results may be significantly altered by some factors such as tyre pressure inflation, the value of the suspended mass and non suspended mass. This paper proposes a method to determine the fundamental characteristics of the suspension system of a vehicle, i.e. stiffness and damping of the suspension. It also can be applied without removing any part during PMVI's and in a reasonable time. Thus, the values of the masses, conditions, type of tyre or the tyre pressure inflation would not affect the test result. From this point of view, it is possible to define a suitable and objective rejection criterion in PMVI's. © Springer Science+Business Media Dordrecht 2013.