Patent ID: 7926736

Claim:
In a fuel injection apparatus for injecting fuel into a combustion chamber of an internal combustion engine, having a fuel injector that can be acted on with highly pressurized fuel by means of a high-pressure fuel source and can be actuated by means of a metering valve device that is able to control the pressure in a pressure booster control chamber so that in a pressure booster pressure chamber delimited by a pressure booster piston, which pressure chamber can be filled via a check valve with fuel from the high-pressure fuel source and communicates with an injection valve member pressure chamber, the pressure booster piston increases the pressure, causing an injection valve member for injecting fuel to open and fuel is injected from the injection valve member pressure chamber into the combustion chamber of the engine, the improvement wherein, in the event of a pressure drop in the high pressure fuel source, the pressure booster piston is situated and designed so that, starting from its neutral position, the pressure booster piston has the capacity to execute a pressure compensation movement by means of which the pressure in the pressure booster pressure chamber is adapted to the reduced pressure of the high-pressure fuel source, and wherein the apparatus further comprises a pressure relief conduit which leads from the pressure booster pressure chamber and communicates with the high-pressure fuel source via the metering valve device; this pressure relief conduit is closed by the pressure booster piston in the neutral state of the fuel injection apparatus and is only opened when a pressure drop occurs in the high-pressure fuel source.