Common-rail fuel-injection system

A common-rail fuel-injection system for an internal combustion engine;

• comprising a fuel supply pump to deliver fuel with pumping action of a plunger, a common rail to store therein the fuel delivered out of the fuel supply pump under pressure, injectors each of which is arranged in each cylinder of the engine, to inject the fuel in the common rail into the cylinders, sensor means to monitor engine operating conditions, a pressure sensor to monitor a pressure in the common rail, and a control unit to find injection factors, including a desired common-rail pressure, of fuel to be injected out of the injectors, depending on signals reported from the sensor means, and further control a fuel delivery forced by the plunger in the fuel supply pump and a fuel injection out of the injector in accordance with the injection factors;
• wherein the pressure sensor detects an actual common-rail pressure at the time between pressure restoration with the fuel delivered by the plunger and pressure drop due to fuel injection out of the injector, and the control unit compensates an amount of fuel to be delivered into the common rail, depending on a deviation of the actual common-rail pressure from the desired common-rail pressure, at every fuel delivery forced by the plunger, so that the actual common-rail pressure coincides with the desired common-rail pressure.