| 摘要 |
PURPOSE:To enable air-fuel ratio to be constant in low opening area of a throttle valve by providing a fuel injection valve on an air inlet path of the upperstream from the throttle valve and adjusting fuel pressure by utilizing negative pressure of the downstream from the throttle valve in an area of less intake air amount. CONSTITUTION:A fuel injection device 21 is provided in Venturi tubes 3, 4 provided upperstream from the throttle valve 5 of an air inlet path 2. And negative pressure taken out from a Venturi negative pressure path 19 is fed to a fuel adjustor 16 and amplified to adjust fuel pressure according to the negative pressure. In an area where throttle valve opening is small and intake air amount is less, the negative pressure from a negative pressure path 33 provided downstream from the throttle valve 5 is input to the fuel adjustor 16 through a switch valve 36 and fuel pressure is adjusted according to the amplified negative pressure. Thus, air-fuel ratio can be controlled constant even in an area of less intake air amount. |
