US Patent 7201146 Control apparatus for internal combustion engine

An engine ECU executes a program including the steps of calculating an in-cylinder injector's injection ratio; if the ratio is 1, calculating a cold state increase value by employing a function f(1) having the engine's temperature as a parameter; if the ratio is 0, calculating a cold state increase value by employing a function f(2) having the engine's temperature as a parameter; and if the ratio is larger than 0 and smaller than 1, calculating a cold state increase value by employing a function f(3) having the engine's temperature and the ratio as parameters.