Method for regulating the rail pressure in a common rail injection system of an internal combustion engine

摘要

A method for open-loop and closed-loop control of an internal combustion engine (1) in which the rail pressure (pCR) is controlled via a low pressure-side suction throttle (4), as the first pressure-adjusting element in a rail pressure control loop. A rail pressure disturbance variable (VDRV) is generated to influence the rail pressure (pCR) via a high-pressure side pressure control valve (12), as the second pressure-adjusting element, by which fuel is redirected from the rail (6) into the fuel tank (2). The position of the high-pressure side pressure control valve (12) is determined by a PWM signal (PWMDV), which, when normal mode is set, is calculated as a function of the resulting target volume flow and, when protective mode is set, is temporarily set to a maximum value.

主权项

1. A method for open-loop and closed-loop control of an internal combustion engine, comprising the steps of: automatically controlling rail pressure (pCR) in a closed-loop rail pressure control system by a suction throttle on a low-pressure side as a first pressure regulator; generating a rail pressure disturbance variable (VDRV) for influencing the rail pressure (pCR) by way of a pressure control valve on a high-pressure side as a second pressure regulator, by which fuel is redirected from a rail into a fuel tank; setting a shutdown mode when an engine shutdown is detected, where the PWM signal (PWMDV) is output with a value of zero when the shutdown mode is set; terminating the shutdown mode and setting a normal mode when an actual rail pressure (pCR(IST)) exceeds an initial value (pSTART) and a verified engine speed (nMOT) is detected; and determining an opening/closing position of the pressure control valve by a PWM signal (PWMDV) by computing the PWM signal (PWMDV) as a function of a resultant set volume flow (Vres(SL)) when the normal mode is set, including setting a protective mode when a dynamic rail pressure (pCR(DYN)) exceeds a maximum pressure value (pMAX) and the protective mode is enabled, and temporarily setting the PWM signal (PWMDV) to a maximum value when the protective mode is set.