Patent ID: 7779816

Claim:
An open-loop and closed-loop control method for an internal combustion engine with a common rail injection system, in which a rail pressure (pCR) is subject to closed-loop control during normal operation, comprising the steps of: determining a first actual rail pressure (pCR 1 (IST)) from the rail pressure (pCR) by a first filter; calculating a control deviation (ep) from a set rail pressure (pCR(SL)) and the first actual rail pressure (pCR 1 (IST)); calculating a correcting variable (qV 1 ) from the control deviation (ep) with a pressure controller; determining a PWM signal (PWM) for controlling a controlled system as a function of the correcting variable (qV 1 ), the PWM signal having a constant base frequency; determining a second actual rail pressure (pCR 2 (IST)) by a second filter; detecting a load reduction when the second actual rail pressure (pCR 2 (IST)) exceeds a first limit (GW 1 ); and, when a load reduction is detected, controlling the rail pressure (pCR) by open-loop control by setting the PWM signal (PWM) to a PWM value (PWM 2 ) that is increased compared to normal operation by a PWM assignment unit. , 17