Fuel Injection System

1 . A fuel injection system for injecting a fuel into a combustion chamber of an internal combustion engine, the system comprising:

a low-pressure system providing the fuel;

a high-pressure fuel pump for applying pressure to the fuel provided by the low-pressure system;

a feed region for feeding the fuel from the low-pressure system to the high-pressure fuel pump;

a pressure chamber in which the high pressure is applied to the fuel;

a low-pressure region fluidically connected to the feed region for supplying the pressure chamber with fuel;

a high-pressure region into which the fuel is delivered from the pressure chamber;

an inlet valve in the pressure chamber for letting fuel from the low-pressure region into the pressure chamber; and

a nonreturn valve arranged upstream of the inlet valve in the direction of flow of the fuel preventing a fuel volume not delivered into the high-pressure region from flowing back out of the pressure chamber into the low-pressure system.

2 . The fuel injection system as claimed in claim 1 , wherein:

the feed region comprises a feed line to feed the fuel from the low-pressure system to the high-pressure fuel pump, the feed line connecting the low-pressure system to a housing of the high-pressure fuel pump; and

the nonreturn valve is arranged in the feed line.

3 . The fuel injection system as claimed in claim 1 , wherein:

the feed region includes a feed port on a housing of the high-pressure fuel pump; and

the nonreturn valve is arranged in the feed port.

4 . The fuel injection system as claimed in claim 1 , further comprising:

a low-pressure damper in the low-pressure region for damping pressure pulsations; and

a damper bore in a housing of the high-pressure fuel pump which connects a damper volume of the low-pressure damper to the feed region;

wherein the nonreturn valve is arranged in the damper bore.

5 . The fuel injection system as claimed in claim 1 , further comprising a low-pressure damper in the low-pressure region for damping pressure pulsations;

wherein a damper volume of the low-pressure damper is at least as large as a displacement volume formed in the pressure chamber.

6 . The fuel injection system as claimed in claim 1 , wherein:

the nonreturn valve includes a spring for preloading a valve element in a closing direction of the nonreturn valve;

a static opening pressure of the nonreturn valve is in a range from 0.03 bar to 0.15 bar; and

a throughflow characteristic in the throughflow region of the nonreturn valve is in a range from 0.1 l/min to 4.5 l/min.

7 . The fuel injection system as claimed in claim 6 , further comprising a predelivery pump for delivering fuel into the feed region;

wherein the predelivery pump generates a feed pressure of the fuel in the feed region; and

the feed pressure is greater than the static opening pressure of the nonreturn valve.

8 . The fuel injection system as claimed in claim 1 , wherein the nonreturn valve has a defined minimum leakage for discharging fuel from the low-pressure region into the low-pressure system.

9 . The fuel injection system as claimed in claim 1 , further comprising a pressure-limiting valve configured to discharge a fuel overpressure occurring in the high-pressure region into the low-pressure region downstream of the nonreturn valve.

10 . The fuel injection system as claimed in claim 1 , wherein the inlet valve comprises a digital, controllable solenoid valve that is open when not energized.

11 . The fuel injection system as claimed in claim 1 , further comprising at least one of a bore or groove connected parallel to the nonreturn valve to discharge fuel from the low-pressure region of the high-pressure fuel pump into the low-pressure system.