F2010D073
Development of an Adaptive Controlled Gas Spring Damper for Passenger Cars
In modern upper class cars a gas spring in combination with an adjustable hydraulic damping is state of the art. For the high volume market of small and medium sized cars the Gas-Spring-Damper (GSD) ought to be presented as a cost effective adaptive damping system. Like the gas spring the GSD has the advantage of payload independent eigenfrequency of the body without the need for an additional adjustable damper. In this way an adaptive controlled GSD can help the driver mastering difficult driving situations. This paper presents actually work from development of a Gas-Spring-Damper Unit. The requirements of a GSD are the same as on other spring and damper system. It has to isolate the body from the high frequency vibrations stimulated by the unevenness of the road surface. It also has to guaranty a proper contact between tire and road for driving safety. The GSD comprises two or three gas chambers working against each other. We are using a GSD of two different sized gas chambers working against each other. A high flow piezoelectric valve solely joins the chambers. The valve is composed of a ring that uses the 3,1-Piezo effect and a hybrid displacement amplification system made of steel and polymer. Both are designed and manufactured in-house by piezoceramic injection moulding. The GSD geometry and pressure defines the payload. His damping depends additional on the valve setting. We developed different strategies for controlling a gas spring damper like force control and state controller. At a component test bed the control strategies are implemented and the performance of the GSD is tested. Therefore the chamber gas pressures, the GSD force and displacement are measured. Additional benefits are generated by connecting the GSD via CAN to the car bus. The GSD control strategy monitors the steering, acceleration and deceleration signals. So it can decrement any overshooting in case of abrupt driver initiated load changes and as well switch the focus from low damping for comfort to high damping for driving safety in critical driving situations. This paper presents a GSD where the damping can be changed within some milliseconds by a self developed high flow piezoelectric valve. The GSD and the control strategies are tested on a test bed. It is shown how this GSD can help to prevent overshooting in the case of abrupt driver initiated load changes. It gives a comparison of classical suspensions, passive GSD and the developed adaptive GSD with high flow pneumatic valve.
This abstract is supplemented by a PDF, which can be viewed here.