METHOD AND CIRCUIT FOR REGULATING THE INITIAL INJECTION BY A DISTRIBUTION PUMP FOR DIESEL FUEL AT A DIESEL ENGINE

摘要

1. A method for controlling the beginning of injection of a distributor injection pump for diesel fuel at a Diesel engine, with a closed loop control for the beginning of injection comprising a reference element (2) which provides a signal of the nominal value of the beginning of injection in dependence on various operation parameters, an actual value indicator (3) which provides a signal of the actual beginning of injection, a comparator (6) for comparing the nominal value with the actual value, and a controller (8) with proportional and integral portion (PI-controller), an open loop control superposing the closed loop control whereby the reference element (2) is connected to the input of a characteristic field unit (12) of the open loop control and the summed up output signals of the characteristic field unit (12) and of the controller (8) are supplied as adjusting values to the injection timing unit (17, 18), and an emergency switch-over unit (7) for an emergency function which cuts-off the controller (8) and renders it inoperative, characterized in that the values of the characteristic field are placed with respect to the beginning of injection so late or the beginnings of injection which result from the characteristic field are so late and close to the top dead centre (TDC) that at instationary operations distinct acoustical improvements are obtained by reducing the acceleration knock especially at acceleration from coasting, and that for the operation of the vehicle in case the emergency switch-over unit (7) has been actuated a switch-over towards earlier beginnings of injection is obtained in that constant correction values and/or correction values of a characteristic field are added to the values of the characteristic field of the open loop control, or a switch-over from the characteristic field of the open loop control to a separate emergency characteristic field takes place.