Fuel injection system

1. A fuel-injection system, comprising:

a high-pressure pump having a pump working space and a pump piston configured to compress a fuel in the pump working space,

a pressure reservoir configured to supply the fuel for injection into cylinders of an engine,

an inlet valve controlling a flow of the fuel into the high-pressure pump from a tank,

an outlet valve controlling a flow of the fuel out of the high-pressure pump into the pressure reservoir,

a control unit configured to control the injection of the fuel into the cylinders and to control operation of the inlet valve and the outlet valve,

wherein the control unit controls the injection of the fuel into the cylinders such that an injection volume of the fuel is taken from the pressure reservoir and injected into one of the cylinders during each work cycle of the engine,

wherein the high-pressure pump is configured to deliver a high-pressure volume of the fuel into the pressure reservoir during each work cycle of the engine,

wherein the high-pressure pump is configured such that the pump piston performs a complete up-and-down motion in the pump working space during a pump stroke,

wherein the control unit is configured to control the inlet valve and the outlet valve such that the high-pressure volume of the fuel produced by the high-pressure pump during each work cycle of the engine corresponds to the injection volume of the fuel taken from the pressure reservoir during the work cycle, and a different high-pressure volume of the fuel per pump stroke is delivered into the pressure reservoir during successive pump strokes during at least two successive work cycles, and

wherein the control unit controls the injection of the fuel into the cylinders such that the injection volume taken from the pressure reservoir is constant during each successive work cycle.

2. The fuel injection system of claim 1 , wherein the control unit is configured to control the inlet valve and the outlet valve such that the respective high-pressure volume of the fuel produced by the high-pressure pump during each of the successive work cycles of the engine corresponds to the injection volume of the fuel taken from the pressure reservoir during each of the successive work cycles of the engine.

3. The fuel injection system of claim 2 , wherein the control unit is configured to control the inlet valve and the outlet valve such that the inlet valve and the outlet valve are opened and closed at different times during successive work cycles of the engine.

4. The fuel injection system of claim 1 , wherein the control unit is configured to control the inlet valve and the outlet valve such that times between a first successive opening or closure of the inlet valve and the outlet valve and a second successive opening and/or closure of the inlet valve and the outlet valve are different.

5. The fuel injection system of claim 4 , wherein the control unit is configured to set the times between a first successive opening or closure of the inlet valve and the outlet valve and a second successive opening or closure of the inlet valve and the outlet valve such that noise emissions which arise during the opening or closure of the inlet valve and the outlet valve are below a limit value.

6. A method for injecting fuel into cylinders of an engine, the method comprising:

providing a high-pressure pump having a pump working space and a pump piston configured to compress a fuel in the pump working space, providing a pressure reservoir configured to supply the fuel for injection into the cylinders of the engine, providing an inlet valve controlling a flow of the fuel into the high-pressure pump from a tank, and providing an outlet valve controlling a flow of the fuel out of the high-pressure pump into the pressure reservoir,

producing a high-pressure volume of the fuel in the high-pressure pump during a work cycle of the engine,

delivering the high-pressure volume of the fuel into the pressure reservoir by the high-pressure pump during the work cycle of the engine,

injecting an injection volume of the fuel into one of the cylinders during the work cycle of the engine, the injection volume controlled by operating the inlet valve and the outlet valve during the work cycle,

wherein the high-pressure volume of the fuel produced by the high-pressure pump during the work cycle corresponds to the injection volume of the fuel taken from the pressure reservoir during the work cycle,

wherein a different high-pressure volume of the fuel per pump stroke is delivered into the pressure reservoir during successive pump strokes during at least two successive work cycles, and

wherein the injection volume taken from the pressure reservoir is constant during each of the successive work cycles.

7. The method of claim 6 , wherein the respective high-pressure volume of the fuel produced by the high-pressure pump during successive work cycles corresponds to the injection volume of the fuel taken from the pressure reservoir during each of the successive work cycles.

8. The method of claim 7 , wherein, during the successive work cycles of the engine, the inlet valve and the outlet valve are opened and closed at different times during the successive work cycles of the engine.

9. The method of claim 6 , wherein times between a first successive opening and/or closure of the inlet valve and the outlet valve and a second successive opening and/or closure of the inlet valve and the outlet valve are different.

10. The method of claim 9 , wherein the times between a first successive opening or closure of the inlet valve and the outlet valve and a second successive opening or closure of the inlet valve and the outlet valve are set such that noise emissions which arise during the opening or closure of the inlet valve and the outlet valve are below a limit value.