Idling rpm feedback control method for internal combustion engines

Claim 1

A method of controlling a control valve for regulating the quantity of supplementary air being supplied to an internal combustion engine, in a feedback manner responsive to the difference between actual engine rpm and desired idling rpm, said engine having an intake passage, a throttle valve arranged in said intake passage, and an air passage having one end communicating with said intake passage at a location downstream of said throttle valve and another end communicating with the atmosphere, respectively, said supplementary air being supplied to said engine through said air pressure and said intake passage, said method comprising the steps of: (a) detecting a value of atmospheric pressure encompassing said engine; (b) determining whether or not said engine is in a predetermined operating condition while said engine is decelerating immediately before entering a region where said feedback control is to be executed; (c) setting the volumetric flow rate of said supplementary air to be supplied to said engine to a value dependent upon the detected value of said atmospheric pressure when it is determined at said step (b) that said engine is operating in said predetermined operating condition; and (d) controlling said control valve so as to supply said supplementary air to said engine at a volumetric flow rate corresponding to the value set at said step (c), after said engine has been determined to be in said predetermined operating condition and until said feedback control is initiated, to thereby stabilize the engine rpm immediately after said feedback control has been initiated.

Claim 2

A method of controlling a control valve for regulating the quantity of supplementary air being supplied to an internal combustion engine, in a feedback manner responsive to the difference between actual engine rpm and desired idling rpm, said engine having an intake passage, a throttle valve arranged in said intake passage, and an air passage having one end communicating with said intake passage at a location downstream of said throttle valve and another end communicating with the atmosphere, respectively, said supplementary air being supplied to said engine through said air pressure and said intake passage, said method comprising the steps of: (a) detecting a value of atmospheric pressure encompassing said engine; (b) determining whether or not said engine is in a predetermined operating condition while said engine is decelerating immediately before entering a region where said feedback control is to be executed; (c) setting the volumetric flow rate of said supplementary air to be supplied to said engine to a value dependent upon the detected value of said atmospheric pressure when it is determined at said step (b) that said engine is operating in said predetermined operating condition; and (d) controlling said control valve so as to supply said supplementary air to said engine at a volumetric flow rate corresponding to the value set at said step (c), after said engine has been determined to be in said predetermined operating condition and until said feedback control is initiated, to thereby stabilize the engine rpm immediately after said feedback control has been initiated.