Patent ID: 7895990
Filing Date: 2011-03-01
Classification: F02D,Y02T

Abstract:
1. A fuel injection system for an internal combustion engine comprising: a fuel injector working to spray fuel into an internal combustion engine; and an injection controller working to perform an injection instruction function when a given learning condition is encountered, the injection instruction function being to instruct said fuel injector to inject the fuel into the internal combustion engine a plurality of times for a given injection duration to learn an injection characteristic representing a relation between an injection duration for which said fuel injector sprays the fuel and a quantity of the fuel actually sprayed from said fuel injector for the injection duration, said injection controller also performing an injection duration changing function, an actual injection quantity determining function, and a correction value determining function, the injection duration changing function being to change the injection duration around a target injection quantity that is a target quantity of the fuel to be sprayed from said fuel injector in each of learning injection events in which said fuel injector is instructed by the injection instruction function to spray the fuel, the actual injection quantity determining function being to monitor a change in operating condition of the internal combustion engine to determine an actual injection quantity that is a quantity of the fuel expected to have been sprayed from said fuel injector in each of the learning injection events, the correction value determining function being to determine the injection characteristic of said fuel injector based on combinations of the actual injection quantities, as determined by the actual injection quantity determining function, and the injection durations for which said fuel injector has sprayed the fuel in the respective learning injection events to calculate an injection duration correction value based on the injection characteristic which is required to correct the injection duration for which said fuel injector is to be instructed to spray the fuel so as to bring a quantity of the fuel to be sprayed from said fuel injector into agreement with the target injection quantity, wherein when an integral average of the actual injection quantities, as determined by the actual injection quantity determining function, is smaller than the target injection quantity, the injection duration changing function defines the greatest of the injection durations, as ever used in the learning injection events, as a reference injection duration and produces the injection duration, which is greater than the reference injection duration, for use in a subsequent one of the learning injection events, and wherein when the integral average of the actual injection quantities is greater than the target injection quantity, the injection duration changing function defines the smallest of the injection durations, as ever used in the learning injection events, as the reference injection duration and produces the injection duration, which is smaller than the reference injection duration, for use in the subsequent one of the learning injection events.