Fuel injection control apparatus for an internal combustion engine

摘要

A fuel injection valve 15 is disposed in an intake passage 9 of an engine body 1. A combustion chamber 5 communicates with the intake passage 9 for introducing fuel injected from the fuel injection valve 15 at predetermined intake timings. A plurality of sensors are provided in the engine body 1 or fuel intake system for detecting various engine operational conditions including properties of fuel. A control unit 30 calculates a fuel quantity-of-state in the combustion chamber 5 in accordance with the engine operational conditions detected by the sensors, using an atomized fuel behavioral model representing behavior of fuel injected from the fuel injection valve 15, an intake passage fuel behavioral model representing fuel behavior in the intake passage 9 and a combustion chamber fuel behavioral model representing fuel behavior in the combustion chamber 5. Furthermore, the control unit 30 calculates a fuel injection amount required to adjust an actual gaseous air-fuel ratio in the combustion chamber 5 to a desired value in accordance with the fuel quantity-of-state thus calculated. The control unit 30 uses a cranking model as the combustion chamber fuel behavioral model before an initial explosion is detected and uses a firing model after the initial explosion is detected. The fuel injection valve 15 is opened or closed on the basis of the fuel injection amount thus calculated.