Patent ID: 6009851
Filing Date: 2000-01-04
Classification: F02B,F02D,Y02T

Abstract:
An idle speed control apparatus for an internal combustion engine, comprising:operation state detecting means for detecting an operation state of the internal combustion engine;air-fuel ratio setting means for setting a target air-fuel ratio in accordance with the engine operation state detected by said operation state detecting means;air-fuel ratio adjusting means for adjusting an air-fuel ratio of an air-fuel mixture supplied to the internal combustion engine to the target air-fuel ratio set by said air-fuel ratio setting means;suction air amount adjusting means for adjusting an amount of suction air into the internal combustion engine;exhaust gas recirculation rate adjusting means for adjusting a rate of exhaust gas recirculation to a suction system of the internal combustion engine;load detecting means for detecting an engine load; andcontrol parameter selecting means for selecting at least one control parameter among the air-fuel ratio, the suction air amount, and the exhaust gas recirculation rate in accordance with the engine load detected by said load detecting means during idle operation of the internal combustion engine;said idle speed control apparatus adjusting a value of said at least one control parameter, selected by said control parameter selecting means, by using a corresponding one or ones of said air-fuel ratio adjusting means, said suction air amount adjusting means, and said exhaust gas recirculation rate adjusting means, thereby controlling an idle speed of the internal combustion engine;said suction air amount adjusting means including at least one air control valve for changing a flow area of a suction pipe of the engine, and said idle speed control apparatus adjusting the suction air amount by changing an opening degree of the air control valve.