Air Spring Air Damper: Modelling and Dynamic Performance in Case of Small Excitations

摘要

Air spring systems gain more and more popularity in the automotive industry and with the ever growing demand for comfort nowadays they are almost inevitable. Some significant advantages over conventional steel springs are appealing for commercial vehicles as well as for the modern passenger vehicles in the luxury class. Current production air spring systems exist in combination with hydraulic shock absorbers (integrated or resolved). An alternative is to use the medium air not only as a spring but also as a damper: a so-called air spring air damper. Air spring air dampers are force elements which could be a great step for the chassis technology due to their functionality (frequency selectivity, load levelling, load independent vibration behaviour, load dependent damping). Some of their design which avoid dynamic seals by the using of rubber bellows contribute to a better ride comfort. This paper is about a simulation model for the air spring air damper (LFD from its German name Luftfederdampfer) combined ith an rubber bellow model. First of all it presents the working properties of the LFD, summarises the state of the art of simulation models for air spring air damper and gives some insight into the physics of such systems and their sensitivity to some parameters. Then it deals with rubber bellow and its behaviour under dynamic excitation. For this purpose, a phenomenological rubber bellow model is presented and validated with measurement. The combined model is calibrated based on an existing air spring air damper hardware, validated with measurements and integrated into a quarter car model for ride comfort simulation. At the end the simulation results are discussed to decide whether or not this should be taken in account for ride comfort simulation.