Fuel injection control system for internal combustion engines

A fuel injection control system for an internal combustion engine having an intake system, at least one combustion chamber, and at least one fuel injection valve disposed to inject fuel into said intake system, comprising:

• operating condition-detecting means for detecting operating conditions of said engine;
• direct supply ratio-calculating means for calculating a direct supply ratio defined as a ratio of a fuel amount directly drawn into said at least one combustion chamber to a whole fuel amount injected by said at least one fuel injection valve, based on the operating conditions of said engine detected by said operating condition-detecting means;
• carry-off ratio-calculating means for calculating a carry-off ratio defined as a ratio of a fuel amount carried off said intake system of said engine and drawn to said at least one combustion chamber to a whole fuel amount which adhered to said intake system, based on the detected operating conditions of said engine;
• main fuel injection amount-calculating means for calculating a main fuel injection amount to be injected by said at least one fuel injection valve, based on said direct supply ratio calculated by said direct supply ratio-calculating means and said carry-off ratio calculated by said carry-off ratio-calculating means;
• fuel amount-increasing operating condition-detecting means for detecting a predetermined operating condition of said engine in which an increased amount of fuel is to be supplied to said engine, based on the detected operating conditions of said engine;
• additional fuel injection amount-calculating means responsive to detection of said predetermined operating condition of said engine by said fuel amount-increasing operating condition-detecting means, for calculating an additional fuel injection amount to be injected by said at least one fuel injection valve, based on the detected operating conditions of said engine, and the calculated direct supply ratio;
• adherent fuel amount-calculating means for calculating an amount of fuel adhering to said intake system of said engine, based on a total sum of said main fuel injection amount calculated by said main fuel injection amount-calculating means and said additional fuel injection amount calculated by said additional fuel injection amount-calculating means, as well as on the calculated direct supply ratio and the calculated carry-off ratio;
• correction means for correcting at least the calculated plurality of said fuel injection amounts, based on said amount of fuel adhering to said intake system calculated by said adherent fuel amount-calculating means;
• and
• control means for controlling said at least one fuel injection valve to sequentially carry out a main fuel injection and an additional fuel injection in one operating cycle of said engine, respectively, based on said main fuel injection amount corrected by said correction means and the calculated additional fuel injection amount.