| 摘要 |
PURPOSE:To cut supply of air when an engine is high and low loaded and reduce harmful exhaust gas, by communicating a negative pressure take-off port for exhaust line secondary air control to the both upstream and downstream when a throttle valve is fully closed. CONSTITUTION:Secondary air is supplied to an exharst port 6 by pulsating action of exhaust from an air cleaner 8 through a pipe 34, control valve Va, pipe 34, reed valve L and passages 35, 36. Though control negative pressure is introduced to a control negative pressure chamber 45 in the control valve Va from a negative pressure chamber 51 through a pipe 52, the chamber 51 is communicated to holes P1 and P2 of the upstream and downstream of a throttle valve Vth when it is fully closed. Accordingly, at operation of a low load when the throttle valve is fully closed, negative pressure in the hole P2 is decreased by the atmospheric pressure, then the control valve Va is closed, while at operation of a high load, when the throttle valve is fully opened, negative pressure in the both holes decreases to close the control valve Va, and at operation excepting the above, the control valve Va is opened by negative pressure in the both holes. In this way, exhaust line secondary air is cut when an engine is low and high loaded. |
