Modeling and control of camless engine valvetrain systems

This dissertation addresses modeling and control issues on both valve motion control and engine management levels of internal combustion (IC) engines under camless operations.; On the valve motion control level, the seating control has been identified to be crucial for the application of electromagnetic camless valve (EMCV) actuators. In this dissertation, open-loop analysis reveals that an EMCV actuator becomes unstable as the engine valve gets closed to its seating position. Therefore, closed-loop control is required to achieve quiet-seating performance. A linear plant model was constructed based on modeling analysis. System identification tests were conducted to find the model parameters. A feedback controller was developed with Linear-Quadratic Regulator design method to stabilize the EMCV actuator. A repetitive learning controller was designed to enhance the control performance through cycle-to-cycle iterations. The control system performance was demonstrated by experimental results.; Camless valvetrain is an enabling system for Regenerative Compression Brake (RCB), i.e. storing and reuse of vehicle kinetic energy in the form of compressed air, which enables any IC engine to run additional (hybrid) modes without the need for another type of propulsion source. This dissertation presents valve timing control logic and modeling results for driving a mid-size car with RCB gasoline engine over the EPA driving cycle, and the associated improvement in fuel economy. Engine valve with fully variable control (timing, event duration and lift) is optimized for RCB and non-RCB modes of operation.; For diesel engines camless technology could also boost the efforts of raising specific power to allow for smaller and more efficient powertrains. Modeling results presented in this dissertation reveals potential for a substantial increase in engine torque by optimizing the intake and exhaust valve timing together with turbocharger operation. However, improved turbocharger performance is needed, which might not be available with current technology. Impact on fuel consumption, and containment of increased peak cylinder pressure are also discussed.