Fuel injection system

摘要

A fuel injection system includes an injector (3) and a control device (5). The injector (3) includes a control chamber (33) that drive-controls a needle (35) with a pressure (Pc) therein. The control device (5) determines a required injection amount (Q) in accordance with an operation state of an internal combustion engine (1), and controls a fuel injection amount injected from the injector through controlling an electric valve (34) therein. The control device (5) determines a geometric shape defined by a time axis and a lift-height change of the needle (35). The control device (5) further divides the lift-height change of the needle (35) during the period from when the needle (35) starts moving up to when the needle (35) starts moving down into a plurality of portions. The control device (5) then evaluates the lift-height change of the needle (35) in the plurality of portions based on a physical equation.