US Patent 7926736 Fuel injection apparatus

An apparatus for injecting fuel into an internal combustion engine having a fuel injector acted on with highly pressurized fuel 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 can be filled via a check valve with high-pressure fuel 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. To assure a correct injection quantity even if an abrupt pressure drop occurs in the high-pressure fuel source, the pressure booster piston is situated and designed so that if a pressure drop occurs in the high-pressure fuel source, then 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 pressure of the high-pressure fuel source.