Patent ID: 6349702
Filing Date: 2002-02-26
Classification: F02D

Abstract:
A common-rail fuel-injection system comprising a common rail to store therein pressurized fuel, injectors each of which is arranged in a cylinder, to inject the fuel supplied from the common rail into the cylinders, sensor means to monitor engine operating conditions, a pressure detector to monitor pressure in the common rail, and a control unit to find fuel-injection factors including a desired amount of fuel to be injected, depending on signals detected from the sensor means, and further calculate an amount of pressure drop taking place in the common-rail due to a fuel injection of each injector, depending on signal detected from the pressure detector, thereby compensating for the desired amount of fuel to be injected from each injector, depending on a deviation of an actual amount of fuel injected from each injector, which is found based on the amount of pressure drop, from the desired amount of fuel to be injected, and wherein the control unit calculates a mean pressure after fuel injection by averaging pulsating pressures that occur in the common rail owing to the fuel injection, and derives the amount of pressure drop in the common rail from a difference in pressure between the mean pressure after fuel injection and a pressure before fuel injection in the common rail,wherein the control unit finds an extreme value in the common-rail pressure, where a derivative of the common-rail pressure becomes zero after the beginning of the pressure drop in the common-rail pressure, and calculates the mean pressure after fuel injection by averaging the extreme values, which happen successively in the common-rail pressure.