Exhaust gas recirculation control system for an internal combustion engine

• US 4,727,849 A
• Filed: 04/23/1987
• Issued: 03/01/1988
• Est. Priority Date: 04/24/1986
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Inoue, Noriyuki, Nishida, Minoru
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US07/041,422
• Time in Patent Office: 313 Days
• Field of Search: 123/440, 123/489, 123/568, 123/569, 123/571, 123/589, 60/276, 60/278, 60/285
• US Class Current: 123/704
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/2474 Characteristics of sensors
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust gas recirculation control system for an internal combustion engine comprises an exhaust gas recirculation control valve for controlling a recirculation rate for exhaust gas to be mixed with intake air which is supplied to the internal combustion engine, an oxygen sensor disposed in an intake air passage downstream of the control valve to detect the concentration of oxygen in the intake air, a control means which compares the oxygen concentration detected by the oxygen sensor with a desired oxygen concentration previously determined depending on operational conditions of the engine and controls the degree of opening of the exhaust gas recirculation control valve so as to cancel the deviation between the detected oxygen concentration and the desired oxygen concentration, a detecting means for detecting the exhaust gas recirculation rate being zero to supply a signal to the control means on the basis of the detection, and a correcting means for correcting the corresponding relation between the output of the oxygen sensor and the detected oxygen concentration on the basis of the output of the oxygen sensor when the exhaust gas recirculation rate is zero.

Claims

1. An exhaust gas recirculation control system for an internal combustion engine which comprises;

an exhaust gas recirculation control valve for controlling a recirculation rate for exhaust gas to be mixed with intake air which is supplied to the internal combustion engine,

an oxygen sensor disposed in an intake air passage downstream of said control valve to detect the concentration of oxygen in the intake air,

a control means which compares the oxygen concentration detected by said oxygen sensor with a desired oxygen concentration previously determined depending on operational conditions of the engine and controls the degree of opening of said exhaust gas recirculation control valve so as to cancel the deviation between the detected oxygen concentration and the desired oxygen concentration,

a detecting means for detecting the exhaust gas recirculation rate being zero to supply a signal to said control means on the basis of the detection, and

a correcting means for correcting the corresponding relation between the output of said oxygen sensor and the detected oxygen concentration on the basis of the output of the oxygen sensor when the exhaust gas recirculation rate is zero.

2. The control system according to claim 1, wherein said desired oxygen concentration to be determined in said control means is calculated on the basis of a desired exhaust gas recirculation rate stored in said control means which is determined in consideration of the revolution number of the engine and the pressure of intake air.

3. The control sytem according to claim 1, wherein said detecting means for producing a signal indicative of the exhaust gas recirculation rate being zero is an aperture detector for detcting the degree of opening of said exhasut gas recirculation control valve.

4. The control system according to claim 1, wherein said detecting means for producing the signal indicative of the exhaust gas recirculation rate being zero is a cooling water temperature sensor, an engine speed detector or an intake air pressure detector.

5. The control system according to claim 1, wherein said control means is adapted to correct the corresponding relation between the detected oxygen concentration and a standard oxygen concentration a predetermined time after the exhaust gas recirculation rate has become zero.