Patent ID: 8844501
Filing Date: 2014-09-30
Classification: F02D,F02M

Abstract:
1. A method for open-loop and closed-loop control of an internal combustion engine with a common rail system, comprising the steps of: controlling rail pressure (pCR) during normal operation by closed-loop control; determining a first actual rail pressure (pCR 1 (IST)) from the rail pressure (pCR) by a first filter; computing a control deviation (ep) from a set rail pressure (pCR(SL)) and the first actual rail pressure (pCR 1 (IST)); computing a correcting variable (qV 1 ) from the control deviation (ep) by a pressure controller; determining a PWM signal (PWM 1 ) with a first PWM frequency (f 1 ) for controlling a controlled system as a function of the correcting variable (qV 1 ); determining a second actual rail pressure (pCR 2 (IST)) by a second filter; detecting a load reduction if the second actual rail pressure (pCR 2 (IST)) exceeds a first limit (GW 1 ), and when the first limit (GW 1 ) is exceeded, switching the PWM signal (PWM 1 ) from the first PWM frequency (f 1 ) to a second PWM frequency (f 2 ); and, when a second limit (GW 2 ) is exceeded, changing control of the rail pressure (pCR) to open-loop control by temporarily setting the PWM signal (PWM 1 ) to a PWM value (PWM 2 ) that is increased compared to normal operation.