Patent ID: 6880527

Claim:
In a fuel injection system for internal combustion engines, having a fuel injector that can be supplied from a high-pressure fuel source, wherein a pressure booster device having a movable pressure booster piston is connected between the fuel injector and the high-pressure fuel source, and the pressure booster piston disconnects a chamber that is connectable to the high-pressure fuel source from a high-pressure chamber communicating with the fuel injector, and by filling a return chamber of the pressure booster device with fuel and by evacuating the return chamber of fuel, the fuel pressure in the high-pressure chamber can be varied, the fuel injector having a movable closing piston for opening and closing injection openings, the closing piston ( 13 ; 113 ) protruding into a closing pressure chamber ( 12 ; 112 ), so that the closing piston can be subjected to fuel pressure to attain a force acting in the closing direction on the closing piston, the closing pressure chamber ( 12 ; 112 ) and the return chamber ( 27 ; 127 ) being formed by a common closing pressure return chamber ( 12 , 27 , 41 ; 112 , 127 , 141 ), and all the portions ( 12 , 27 ; 112 , 127 ) of the closing pressure return chamber communicate ( 41 ; 141 ) permanently with one another for exchanging fuel, a pressure chamber ( 17 ; 128 ) for supplying injection openings with fuel and for exerting a force acting in the opening direction on the closing piston, the high-pressure chamber ( 28 ) being in communication ( 43 ; 70 , 41 , 42 ; 1700 , 1410 , 42 ) with the high-pressure fuel source in such a way that in the high-pressure chamber, except for pressure fluctuations, at least the fuel pressure of the high-pressure fuel source can prevail constantly; the pressure chamber and the high-pressure chamber being formed by a common injection chamber; and wherein all the portions of the injection chamber communicate with one another permanently for exchanging fuel.