Piezoelectric fuel injection: Cycle-to-cycle control of tightly spaced injections

Abstract: Piezoelectric fuel injectors will require closed-loop control to realize tightly spaced injections. This paper describes an estimation algorithm for cycle-to-cycle determination of an injection flow profile for use as feedback for closed-loop control. A control design-amenable, 2-pulse approximate model is outlined to represent the dynamics of simultaneously controlling the quantity of, and realized dwell time between, injection pulses. A control law is developed to provide an overdamped response of realized dwell time to prevent pulse bleeding. Closed-loop performance is validated with the experimental data. Desired fuel quantity, and very short dwell times of 0.0002s (two crank angle degrees at 1800RPM), are realized with tracking error convergence time constants of approximately four engine cycles (0.27s at 1800RPM). [Copyright &y& Elsevier]