Patent ID: 6971368

Claim:
A fuel injection system for an internal combustion engine, comprising: A a fuel supply pump for supplying fuel under pressure to a fuel injection valve in the internal combustion engine; B a fuel pressure detector for detecting the pressure of the fuel supplied under pressure from the fuel supply pump to the fuel injection valve; and C a fuel pressure control unit for controlling the amount of the fuel supplied under pressure from the fuel supply pump based on a deviation between an actual fuel pressure detected by the fuel pressure detector and a target fuel pressure which is set in accordance with an operating condition of the internal combustion engine, wherein the fuel pressure control unit comprises: an integral term calculator for adding an integral compensation quantity and a last-time integral term to calculate a this-time integral term, the integral compensation quantity being updated in accordance with the deviation between the actual fuel pressure and the target fuel pressure; and an integral term holder that stops updating of the integral compensation quantity and retains the last-time integral term when a pressure-supply defect of the fuel supply pump is detected, and wherein the time when a pressure-supply defect of the fuel supply pump is detected indicates any of the period in which a failure or a control defect of the fuel supply pump is detected, the period until the lapse of a predetermined time after a failure or a control defect of the fuel supply pump is no longer detected from the time when the failure or the control defect has been detected, and the period until the operation of the internal combustion engine is stopped from the time when a failure or a control defect of the fuel supply pump has been detected.