| 摘要 |
PURPOSE:To enlarge the control width of air-fuel ratio by a method wherein air bleed, supplied to the upstream of main fuel jet of a variable venturi carburettor, is controlled. CONSTITUTION:A piston 27 slides in accordance with the vacuum at the downstream of a variable venturi piston 17, changing in accordance with the opening degree of a throttle valve 42, to keep the vacuum at the downstream of a piston 27 in constant. The main fuel nozzle, provided at the venturi section, is provided with a main fuel jet 21 and a main air bleed pipe 25 is opened at the upstream of a fuel path for the main fuel jet 21. The main air bleed pipe 25 is provided with a solenoid valve 28 driven by a control circuit 35 in accordance with the temperature 30, the revolving number 31 and the vacuum 32 of an engine in order to effect a duty ratio control in accordance with the condition of the engine. The downstream vacuum PA of the main fuel jet 21 is constant at all times, however, the upstream vacuum PB of the same is controlled by the solenoid valve 28 and the air-fuel ratio may be controlled in a range wider than simple air bleed amount control. |
