FUEL INJECTION CONTROL SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

At least after off of an injection pulse of partial lift injection, a difference between a first filtered voltage being a negative terminal voltage of a fuel injection valve filtered by a first low-pass filter and a second filtered voltage being the terminal voltage filtered by a second low-pass filter is calculated, and time from a predetermined reference timing to a timing when the difference between the filtered voltages has an inflection point is calculated as voltage inflection time. Subsequently, an injection quantity corresponding to current voltage inflection time is estimated for each of injection pulse widths with a relationship between the voltage inflection time and the injection quantity, the relationship being beforehand stored for each of the injection pulse widths. A map defining the relationship between the injection pulse width and the injection quantity is created based on a result of such estimation, and a required injection pulse width corresponding to a required injection quantity is calculated using the map.

主权项

1. A fuel injection control system of an internal combustion engine having an electromagnetic driving fuel injection valve, the fuel injection control system comprising:
an injection control means portion that performs full lift injection to drive the fuel injection valve to open with an injection pulse allowing a lift amount of a valve element of the fuel injection valve to reach a full lift position, and performs partial lift injection to drive the fuel injection valve to open with an injection pulse allowing the lift amount of the valve element not to reach the full lift position; a filtered-voltage acquisition portion that, after off of the injection pulse of the partial lift injection, acquires a first filtered voltage being a terminal voltage of the fuel injection valve filtered by a first low-pass filter having a first frequency as a cutoff frequency, the first frequency being lower than a frequency of a noise component, and acquires a second filtered voltage being the terminal voltage filtered by a second low-pass filter having a second frequency as a cutoff frequency, the second frequency being lower than the first frequency; a difference calculation portion that calculates a difference between the first filtered voltage and the second filtered voltage; a time calculation portion that calculates time from a predetermined reference timing to a timing when the difference has an inflection point as voltage inflection time; and an injection pulse correction portion that corrects the injection pulse of the partial lift injection based on the voltage inflection time, wherein the injection pulse correction portion has a storage portion that beforehand stores a relationship between the voltage inflection time and the injection quantity for each of a plurality of injection pulse widths each providing the partial lift injection, and calculates a required injection pulse width corresponding to a required injection quantity based on the relationship between the voltage inflection time and the injection quantity, the relationship being beforehand stored in the storage portion for each of the injection pulse widths, and based on the voltage inflection time calculated by the time calculation portion.