Patent ID: 6076502
Filing Date: 2000-06-20
Classification: F02D,F02M,Y02T

Abstract:
An exhaust gas recirculation control system for internal combustion engines, comprising:an exhaust gas recirculation passage for recirculating a part of an exhaust gas from an internal combustion engine into the engine;an exhaust gas recirculation control valve for controlling a flow rate of the exhaust gas flowing in the exhaust gas recirculation passage;an opening degree controller for controlling an opening degree of the exhaust gas recirculation control valve;an operating condition detector for detecting an operating condition of the engine;means for setting a target exhaust gas recirculation ratio depending on the detected operating condition;a combustion state detector for detecting a combustion state in at least one cylinder of the engine;means for finding an actual exhaust gas recirculation ratio of the engine based on the detected combustion state; andmeans for controlling the opening degree controller so as to bring the actual exhaust gas recirculation ratio to the target exhaust gas recirculation ratio,wherein the combustion state detector comprises an ion current detector for flowing an ion current in at least one cylinder in the engine and detecting the ion current flowing therein, means for flowing a signal indicative of the ion current in a predetermined period of time to carry out generation and detection of a current component corresponding to a combustion level in the cylinder, combustion state quantity finding means for finding a combustion state quantity in the cylinder based on the detected current component, and combustion variable quantity finding means for finding a variable quantity in the cylinder based on the combustion state in a present cycle and the combustion state in a cycle prior to the present cycle found by the combustion state quantity finding means.