Operating method for operating a fuel injection system and fuel injection system

An operating method for operating a fuel injection system of an internal combustion engine, the method comprising:

• providing a fuel injection system, having a high-pressure fuel pump with a pump piston which is movable in translational fashion in a pressure chamber during operation and which serves for highly pressurizing a fuel, having a high-pressure region for storing the highly pressurized fuel, and having at least one injector valve which is connected to the high-pressure region and which serves for injecting highly pressurized fuel into a combustion chamber of the internal combustion engine;
• providing at least two operating states of the internal combustion engine, wherein, in an overrun mode, no injection of fuel through the at least one injector valve into the combustion chamber takes place, wherein, in an injection mode, at least one injection of fuel through the at least one injector valve into the combustion chamber takes place;
• providing a pressure-limiting valve which, when a predefined opening pressure is reached in the high-pressure region, discharges fuel from the high-pressure region into the pressure chamber of the high-pressure fuel pump;
• detecting a fault situation in the fuel injection system, wherein the predefined opening pressure is overshot in the high-pressure region;
• deactivating the overrun mode of the internal combustion engine in the fault situation, such that the internal combustion engine is operated exclusively in the injection mode;
• determining a period duration with four evenly distributed quadrants between a first top dead center time, at which the pump piston is at the top dead center, and a second top dead center time, at which the pump piston is at the top dead center, defining an injection time at which the at least one injector valve begins to inject fuel, and
• adjusting a camshaft angle of the camshaft relative to the pump piston such that the injection time lies in a duration which extends in at least one of a second quadrant of the period duration and a third quadrant of the period duration.

A fuel injection system for injecting fuel into combustion chambers of an internal combustion engine, the fuel injection system comprising:

• a high-pressure fuel pump with a pump piston which moves in translational fashion in a pressure chamber during operation and which serves for highly pressurizing a fuel;
• a high-pressure region for storing the highly pressurized fuel;
• at least one injector valve which is connected to the high-pressure region and which serves for injecting highly pressurized fuel into a combustion chamber of the internal combustion engine;
• a pressure-limiting valve which, when a predefined opening pressure is reached in the high-pressure region, discharges fuel from the high-pressure region into the pressure chamber of the high-pressure fuel pump;
• and
• a control device which is configured to
• provide at least two operating state of the internal combustion engine, wherein, in an overrun mode, no injection of fuel through the at least one injector valve into the combustion chamber takes place, wherein, in an injection mode, at least one injection of fuel through the at least one injector valve into the combustion chamber takes place;
• detect a fault situation in the fuel injection system, wherein pressure in the high-pressure region exceeds the predefined opening pressure;
• and
• deactivate the overrun mode of the internal combustion engine in the fault situation, such that the internal combustion engine is operated exclusively in the injection mode,
• wherein pressure in the high-pressure region has cyclic pressure peaks and pressure troughs,
• wherein a period duration with four evenly distributed quadrants is determined between a first top dead center time at which the pump piston is at a top dead center, and a second top dead center time at which the pump piston is at the top dead center, and
• wherein the at least one injector valve is actuated such that an opening time of the at least one injector valve lies in an opening duration which extends in at least one of a second quadrant of the four evenly distributed quadrants of the period duration and a third quadrant of the four evenly distributed quadrants of the period duration, the second and third quadrants corresponding to a trough of the pressure troughs.

A fuel injection system for injecting fuel into combustion chambers of an internal combustion engine, the fuel injection system comprising:

• a high-pressure fuel pump with a pump piston which moves in translational fashion in a pressure chamber during operation and which serves for highly pressurizing a fuel;
• a high-pressure region for storing the highly pressurized fuel;
• at least one injector valve which is connected to the high-pressure region and which serves for injecting highly pressurized fuel into a combustion chamber of the internal combustion engine;
• a pressure-limiting valve which, when a predefined opening pressure is reached in the high-pressure region, discharges fuel from the high-pressure region into the pressure chamber of the high-pressure fuel pump;
• and
• a control device which is configured to
• provide at least two operating state of the internal combustion engine, wherein, in an overrun mode, no injection of fuel through the at least one injector valve into the combustion chamber takes place, wherein, in an injection mode, at least one injection of fuel through the at least one injector valve into the combustion chamber takes place;
• detect a fault situation in the fuel injection system, wherein pressure in the high-pressure region exceeds the predefined opening pressure;
• and
• deactivate the overrun mode of the internal combustion engine in the fault situation, such that the internal combustion engine is operated exclusively in the injection mode,
• wherein pressure in the high-pressure region has cyclic pressure peaks and pressure troughs, and wherein the control device is further configured to determine a period duration with four evenly distributed quadrants between a first top dead center time, at which the pump piston is at the top dead center, a second top dead center time, at which the pump piston is at the top dead center, define an injection time at which the at least one injector valve begins to inject fuel, and adjust at least one of the injection time and a camshaft angle of the camshaft relative to the pump piston such that the injection time lies in a duration which extends in at least one of a second quadrant of the period duration and a third quadrant of the period duration, the second and third quadrants corresponding to at least one of the pressure troughs.