Fuel injection device for an internal combustion engine

A fuel injection system for an internal combustion engine, comprising

• a respective high-pressure fuel pump (10) and a fuel injection valve (12) connected to it for each cylinder of the internal combustion engine,
• the high-pressure fuel pump (10) having a pump piston (18) driven into a stroke motion and delimiting a pump working chamber (22), which can be connected to a low-pressure region (25) via a connection (21) that is controlled by an electrically actuated control valve (60),
• the fuel injection valve (12) having an injection valve element (28) that controls at least one injection opening (32) and is acted on in an opening direction (29) by the pressure prevailing in a pressure chamber (40), which can be connected to the pump working chamber (22),
• an electrical control element (64) controlling an opening and closing motion of the injection valve element (28),
• a pressure reservoir (68) communicating with the pump working chamber (22) via a connection (66) through which fuel is delivered into the pressure reservoir (68) during the delivery stroke of the pump piston (18) and also communicating with the pressure chamber (40) of the fuel injection valve (12) via the connection (66) through which the pressure chamber (40) can be supplied with fuel from the pressure reservoir (68) for a fuel injection via the fuel injection valve (12) independent of the delivery stroke of the pump piston (18),
• the connection (66) of the pressure reservoir (68) to the pump working chamber (22) and pressure chamber (40) containing a coupling device (70;
• 170;
• 270), which contains a sliding piston (74;
• 174;
• 274) that is acted on at one end by the pressure prevailing in the pressure reservoir (68) and is acted on at the other end by the pressure prevailing in the connection (66),
• the piston (74;
• 174;
• 274) executing a delivery stroke oriented toward the pressure chamber (40) in order to execute a fuel injection, and
• the coupling device (70;
• 170;
• 270) containing a bypass connection (76, 77;
• 176;
• 276, 277) via which the connection (66) communicates with the pressure reservoir (68).