Control system for internal combustion engines

A control system for an internal combustion engine having an intake passage having an inner wall surface, a fuel tank, at least one fuel injection valve, at least one combustion chamber, and an evaporative emission control system, said evaporative emission control system including a canister for adsorbing evaporative fuel generated from said fuel tank, a purging passage connecting between said intake passage and said canister, a flowmeter arranged in said purging passage for generating an output indicative of a flow rate of a gas containing said evaporative fuel and purged through said purging passage into said intake passage, and a purge control valve for controlling the flow rate of said gas,

• the control system comprising:
• auxiliary air supply means for supplying auxiliary air to said engine,
• operating condition-detecting means for detecting operating conditions of said engine including at least the rotational speed of said engine and load on said engine;
• purging flow rate-calculating means for calculating a value of said flow rate of said gas based on results of detection by said operating condition-detecting means;
• concentration-calculating means for calculating concentration of evaporative fuel contained in said gas based on a result of calculation by said purging flow rate-calculating means and said output from said flowmeter;
• purged gas volume-calculating means for calculating a volume of said gas purged over a predetermined time period, based on said output from said flowmeter;
• purged gas dynamic characteristic-determining means for calculating a Datameter indicative of dynamic characteristics of said gas based on a result of detection by said operating condition-detecting means;
• purged air amount-calculating means for calculating an amount of air contained in said purged gas drawn into said combustion chamber during the present cycle of operation of said engine, at least based on a result of calculation by said concentration-calculating means, a result of calculation by said purged gas volume-calculating means, and a result of calculation by said purged gas dynamic characteristic-determining means;
• and
• auxiliary air amount control means for controlling an amount of auxiliary air supplied by said auxiliary air supply means depending on a result of calculation by said purged air amount-calculating means.