Analysis of Active and Semi-Active Vehicle Suspensions Fitted with a Pneumatic Self-Energizing Levelling Device

Abstract

A pneumatic self-energizing self-levelling (SESL) device is proposed in schematic form and a theoretical analysis of it is carried out. The unit allows the design suspension working space to be maintained once steady state operating conditions have been reached. Conventional passive, semi-active and fully active suspensions are all disadvantaged by variable vehicle payloads. An investigation is carried out to determine what advantages are to be gained by combining the SESL unit with each of these types of suspension. Computing simulations have been used to show that for large payloads it has the ability to: (a) improve the performance of a conventional passive suspension, (b) reduce the power requirements of a fully active system and (c) maintain the performance of a semi-active system close to that of a fully active system for a wide range of payloads. It is concluded that the SESL device has most to offer when it is used in conjunction with a semi-active system containing a variable-rate switchable damper.