PURPOSE: To prevent overthinning of fuel-air mixture, by a method wherein, in a device which feeds secondary air flowing around a throttle valve, when the number of revolutions of an engine is decreased to lower than a specified value during a given time when a clutch situated to an engine power transmission system is disengaged, the feed of secondary air is shut off.
CONSTITUTION: A titled device is constituted such that a secondary air control valve 16 is located in an air passage 15 through which an air cleaner 11 is communicated with a suction passage 13 located down a line from a throttle valve 14. The secondary air control valve 16 is opened and closed according to a difference in a pressure between an air chamber 162, communicated with a suction passage 13, located down a line from a throttle valve 14, through a negative pressure pipe 17 and an air chamber 163 in which a negative pressure is introduced through a negative pressure pipe 18 in which a solenoid valve 20 connectable to the open air is situated. The solenoid valve 20 is adapted to be energized by a secondary air control instruction means 4, having a timer 7 started when a clutch is disengaged and a clutch switch 1 is turned ON, when the number of revolutions of an engine is decreased to lower than a specified value until counting of a timer 7 is completed, to close the secondary air control valve 16.
ASAKURA MASAHIKO
KIMURA KATSUHIKO
SHIINA TAKANORI
Next Patent: JPS6278469