Electro-Pneumatic Exhaust Valve Modeling and Control for an Internal Combustion Engine

Variable valve actuation of Internal Combustion (IC) engines is capable of significantly improving their performance. It can be divided into two main categories: variable valve timing with cam shaft(s) and camless valve actuation. For camless valve actuation, research has been centered in electro-magnetic, electro-hydraulic, and electro-pneumatic valve actuators. This research studies the control of the electro-pneumatic valve actuator. The modeling and control of intake valves for the Electro-Pneumatic Valve Actuators (EPVA) was shown in early publications and this paper extends the EPVA modeling and control development to exhaust valves for the lift control which is the key to the exhaust valve control since an accurate and repeatable lift control guarantees a satisfactory valve closing timing control. Note that exhaust valve closing timing is a key parameter for controlling engine residual gas recirculation. The exhaust valve lift control challenge is the disturbance from the randomly varying in-cylinder pressure against which the exhaust valve opens. The developed strategy utilizes model based predictive techniques to overcome this disturbance. This exhaust valve lift control algorithm was validated on a 5.4 Liter 3 valve V8 engine head with a pressurized chamber to imitate the in-cylinder pressure. The experimental results demonstrated that the exhaust valve lift tracked the step reference in one cycle with the lift error under 1mm and the steady state lift error was kept below 1mm.