Feedback control system for recirculation of exhaust gas

Claim 1

A feedback control system for controlling the recirculation of exhaust gas from an exhaust passage of an internal combustion engine to an induction passage of the engine through an exhaust recirculation passage, the system comprising: a flow control valve to vary the volume flow rate of the exhaust gas in the exhaust recirculation passage; a sensor means for sensing the concentration of a component of the exhaust gas in a gas mixture flowing in the induction passage at a location downstream of the junction of the induction passage and the exhaust recirculation passage and producing an electrical signal representing the sensed concentration, said component being a gaseous substance the amount of which in the exhaust gas being nearly constant during operation of the engine; a control means for producing a control signal based on said electrical signal, said control signal indicating a decrease in the volume flow rate of the exhaust gas in the recirculation passage when said electrical signal implies that said concentration is higher than a reference value and an increase in said volume flow rate when said electrical signal implies that said concentration is lower than said reference value; and an actuator means for operating said control valve in response to said control signal.

Claim 7

A method of controlling the recirculation of a portion of exhaust gas of an internal combustion engine through the engine, comprising the steps of: measuring the concentration of a component of the exhaust gas in a gas mixture which is produced by the admission of the recirculated exhaust gas into an induction passage for the engine, said component being a gaseous substance the amount of which in the exhaust gas is nearly constant during operation of the engine; comparing the measured concentration with a reference value; and regulating the quantity of the exhaust gas being recirculated so as to decrease said quantity when the measured concentration is higher than said reference value and increase said quantity when the measured concentration is lower than said reference value.

Claim 8

A method of controlling the recirculation of a portion of exhaust gas of an internal combustion engine through the engine, comprising the steps of: measuring the concentration of a component of the exhaust gas in a gas mixture which is produced by the admission of the recirculated exhaust gas into an induction passage for the engine, said component being a gaseous substance the amount of which in the exhaust gas is nearly constant during operation of the engine; comparing the measured concentration with a reference value; and regulating the quantity of the exhaust gas being recirculated so as to decrease said quantity when the measured concentration is higher than said reference value and increase said quantity when the measured concentration is lower than said reference value.