| 摘要 |
PURPOSE:To improve the starting and warm-up of an engine, by moving a pressure response piston in such a direction as to decrease the cross-sectional area of a Venturi part at the low temperature of the engine to prevent the mixture of air and fuel from becoming too thick at the closure of a choke valve. CONSTITUTION:Normally, intake air flows in a direction A depending on the degree of opening of a throttle valve 3 and a piston 6 is moved depending on the difference between the atmospheric pressure in an air passage 9 and the intake negative pressure or Venturi negative pressure in an air passage 10. For that reason, the piston 6 is moved up and fuel injected from a main nozzle 13 is increased as the rotational frequency of an engine rises. When the temperature of the engine is low, a control circuit 22 operates a solenoid valve 21 through a drive circuit 23 depending on the output voltage of a cooling water temperature sensor 24, for example, to connect the top of an intake air chamber 5 to an atmosphere release port 19 to prevent the excessive rise in the Venturi negative pressure and therefore prevent the excessive increase in the quantity of the injected fuel. |
