초록

A method for operating a fuel injection system in which in idling or partial-load operation, the pumping performance of the high-pressure fuel pump is made uniform. This has a positive effect on the quietness of engine operation and on the quality of regulation of the pressure in the common rail.

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The invention claimed is: 1. A method for operating a fuel injection system of an internal combustion engine, having a high-pressure fuel pump (17), wherein the high-pressure fuel pump (17) has a plurality of pump elements (19), having a metering valve (47) disposed on the intake side of the high-p

The invention claimed is: 1. A method for operating a fuel injection system of an internal combustion engine, having a high-pressure fuel pump (17), wherein the high-pressure fuel pump (17) has a plurality of pump elements (19), having a metering valve (47) disposed on the intake side of the high-pressure fuel pump (17), wherein the fuel quantity aspirated by the pump elements (19) can be controlled or regulated by the metering valve (47), having a common rail ( 25), and having a pressure regulating valve (51), wherein the pressure in the common rail (25) is controlled or regulated by the pressure regulating valve (51), the method comprising the steps of detecting or calculating the pumping quantity (mHDP, eff) pumped by the high-pressure fuel pump (17); triggering the pressure regulating valve (51), if the pumping quantity (mHDP, eff) is less than a predetermined limit value (mGrenz), so that a defined leakage occurs at the pressure regulating valve (51); and triggering the metering valve (47) such that a predetermined set-point pressure (Ppoint) in the common rail is established. 2. The method of claim 1, wherein the limit value (m Grenz) is freely selectable. 3. The method of claim 1, wherein the closing force of the pressure regulating valve (51) is reduced so far that the required defined leakage occurs at the pressure regulating valve (51). 4. The method of claim 2, wherein the closing force of the pressure regulating valve (51) is reduced so far that the required defined leakage occurs at the pressure regulating valve (51). 5. The method of claim 3, wherein the closing force of the pressure regulating valve (51) is controlled by varying the ratio between the periods of time in which the pressure regulating valve ( 51) is currentless and the periods of time in which current is supplied to the pressure regulating valve (51). 6. The method of claim 4, wherein the closing force of the pressure regulating valve (51) is controlled by varying the ratio between the periods of time in which the pressure regulating valve ( 51) is currentless and the periods of time in which current is supplied to the pressure regulating valve (51). 7. The method of claim 1, wherein the triggering of the pressure regulating valve (51) is effected as a function of a set-point pressure in the common rail (25) and as a function of an rpm at which the high-pressure fuel pump (17) is driven, or the engine rpm. 8. The method of claim 2, wherein the triggering of the pressure regulating valve (51) is effected as a function of a set-point pressure in the common rail (25) and as a function of an rpm at which the high-pressure fuel pump (17) is driven, or the engine rpm. 9. The method of claim 3, wherein the triggering of the pressure regulating valve (51) is effected as a function of a set-point pressure in the common rail (25) and as a function of an rpm at which the high-pressure fuel pump (17) is driven, or the engine rpm. 10. The method of claim 5, wherein the triggering of the pressure regulating valve (51) is effected as a function of a set-point pressure in the common rail (25) and as a function of an rpm at which the high-pressure fuel pump (17) is driven, or the engine rpm. 11. The method of claim 1, wherein the method is employed only if the current pumping quantity (mHDP, eff) of the high-pressure fuel pump (17) is less than the applied limit value (m Grenz). 12. The method of claim 2, wherein the method is employed only if the current pumping quantity (mHDP, eff) of the high-pressure fuel pump (17) is less than the applied limit value (m Grenz). 13. The method of claim 1, wherein the triggering of the pressure regulating valve (51) is stored in memory in one or more performance graphs. 14. The method of claim 2, wherein the triggering of the pressure regulating valve (51) is stored in memory in one or more performance graphs. 15. The method of claim 1, wherein the triggering of the pressure regulating valve (51) is effected by means of a controller. 16. The method of claim 1, wherein the pumping quantity (m HDP, eff) of the high-pressure fuel pump (17) is ascertained from the fuel quantity flowing through the metering valve (47). 17. The method of claim 1 performed by a computer program stored in the memory of a computer storage medium. 18. A control unit for a fuel injection system of an internal combustion engine suitable for performing a method of claim 1.