PURPOSE: To prevent air-fuel ratio from changing overlean, by controlling a flow regulating valve in an intake secondary air supply passage to an opening throttled smaller than the control opening, calculated in accordance with an operation parameter, when a car speed or an engine speed is in a predetermined value or less in the time of engine deceleration.
CONSTITUTION: A linear type solenoid valve 9, serving as a flow regulating valve, is provided interposing in an intake secondary air supply passage 8 which is connected to an intake passage so as to detour around a throttle valve 3 in a carburetor 1. And when a control circuit 20 discriminates an engine deceleration condition by a pressure in an intake pipe in the downstream of the throttle valve 3 detected by an absolute pressure sensor 10, the solenoid valve 9 is actuated opening so as to obtain a control opening, calculated in accordance with an operative parameter, preventing air-fuel ratio from changing overrich. In a device such as the above, when a car speed in a predetermined value or less or an engine speed in a predetermined value or less is detected at the time of engine deceleration, the solenoid valve 9 reduces its opening from the above described control opening, preventing the air-fuel ratio from changing overlean.
IKURA HIROSHI
KUBO SATORU
