PURPOSE: To maintain the combustion of fuel preferable and to reduce effectively the production of detrimental components from the fuel by variably controlling simultaneously the ignition timing in a system for recirculating exhaust gas in response to the operating state of the engine to thereby reduce NOX in the exhaust gas.
CONSTITUTION: At an air flowmeter 8 and a throttle valve 5 provided within the suction manifold 2 of an engine are provided an air amount sensor 9 and a throttle valve opening sensor 6, the signals from which and signals from a coolant sensor 7 and revolution number sensor 11 provided at a distributor are applied to a microcomputer 16. The suction manifold 2 communicates through a tube 13a having an exhaust gas recirculating valve 13 with an exhaust manifold 4. Then, a vacuum control valve 14 for switching the vacuum to the vacuum chamber 13f of the valve 13 is opened or closed by the microcomputer 16. The distributor is further controlled by the microcomputer 16 at a timing for recirculating the exhaust gas to the suction manifold 2 to thereby advance the ignition timing so as to thus raise the combustion effect.
MIYAGI HIDEO
YOSHIDA MATSUHISA
OOMORI NORIO
TOYOTA MOTOR CO LTD