PURPOSE: To raise the catalyst performances and save the fuel cost of internal combustion engines by controlling an EGR passage having a secondary air suction part for a suction air and exhaust gas system, and the secondary air of another exhaust gas system in accordance with the output of an exhaust gas sensor.
CONSTITUTION: Secondary air is supplied to an EGR passage communication with a suction system via the opening 24 of an exhaust gas pipe 5, a throttle 26, a chamber 28, a control valve 15, a pipe 22 and an opening 21, and to a chamber 28 via a cleaner 3, a lead valve 31 and a throttle 29. The valve 15 is opened and closed when the change-over of the chamber of a valve 17 is made to negative pressure and atmospheric pressure through the operation of a 3-way valve 10 in accordance with the signal of a controller 9 operating in accordance with the output of an exhaust gas sensor 7. When the valve 15 is opened or closed, secondary air enters an air suction system together with EGR, or an exhaust gas system respectively. Further, a valve 38 is opened and closed in accordance with the signal of a controller 9 to control another secondary air passage for supplying the exhaust gas system via a lead valve 36, a pipe 34, a throttle 33 and an opening 25 for the optimum control of engine.