Air-fuel ratio control device for injection carburetors.

摘要

The air-fuel ratio control device for injection carburetors is equipped with a slow fuel control unit (14) and a main fuel control unit (15) each of which comprises a negative pressure diaphragm (10 min ) forming a depression chamber for receiving negative pressures produced dependently on flow rates of air to be sucked, and a fuel injection valve (12 min ) for opening and closing a fuel injection port (8a min ) dependently on displacement of the negative pressure diaphragm. Communicated with the depression chamber of the slow fuel control unit (25) is a bypass passage (26) for introducing negative pressures into said depression chamber, and provided in the bypass passage is an adjusting screw (28) capable of adjusting effective cross sectional area thereof. This air-fuel ratio control device is capable of maintaining air-fuel ratio of the mixture at an adequate constant level from the idling condition to the slow zone, prevents fuel leakage at rest time of engine and enables to provide carburetors having very excellent responsibility over the entire operating range of engine.