Dynamics and control of an electro-hydraulic fully flexible valve actuation system

As the internal combustion engine moves into the 21/sup st/ century, fully flexible valve actuation (FFVA) systems are being proposed as an enabling technology for advanced internal combustion engine concepts. This paper focuses on exploring the dynamics and control of an electro-hydraulic fully flexible valve actuation system. Challenges and approaches for developing variable valve actuation systems are first outlined and discussed. Dynamic model of the electro-hydraulic actuator was obtained based on experimental data. A robust repetitive controller is then designed and implemented using a dSpace system. We are able to achieve valve profile tracking errors within 140 microns for a 9.5 mm lift at engine speed up to 3000 rpm. To demonstrate the flexibility and robustness of the system, we show real-time valve-lift profiles used to explore advanced combustion technologies.