| 摘要 |
PURPOSE:To reliably prevent the generation of after burn just prior to the end of rapid deceleration or the like, by providing a vacuum type shut-off valve in a secondary air induction passage connected to an exhaust passage, and providing a fuel increasing device in a suction passage so as to increase a fuel quantity at deceleration. CONSTITUTION:An air supply nozzle 9 as a secondary air supply device is provided in an exhaust passage 6, and is connected through an air induction passage 10 to an air purifier 8. A shut-off valve 12 is provided in the air induction passage 10. The shut-off valve 12 is adapted to be closed by inducing a suction vacuum downstream of a carburetor 7 through a piping 15 to a diaphragm chamber 14 and thereby operating a diaphragm 13. Two stages of restrictions 16 and 17 are provided in the piping 15 so as to eliminate a response delay at the beginning of valve closing. The carburetor 7 is provided with a pilot jet 18 as a fuel increasing device in an air passage 19 opening into the vicinity of a throttle valve 26. |
