Fuel supply apparatus for internal combustion engines

Abstract

A fuel supply apparatus for internal combustion engines of a type including an air valve disposed in an intake conduit of the engine upstream of a throttle valve. A sensor is used for sensing the pressure in an air pressure chamber defined within the intake conduit between the air valve and the throttle valve and a feedback control unit is used for controlling the air valve in response to the pressure sensed by the sensor in order to maintain the pressure in the air pressure chamber at a preset value. A fuel flow metering valve is disposed in a fuel feed channel leading from a source of fuel under pressure to the intake conduit and the metering value is interlocked with the air valve in such a manner that the opening degree of the fuel metering valve is in proportion to that of the air valve. Also a pressure difference control unit is employed for maintaining the pressure difference of fuel across the fuel metering valve at a preset value, whereby the air-fuel ratio of an air-fuel mixture is maintained constant independently of the engine speed. The fuel supply apparatus of the above type further comprises a variable volume chamber defined by a cylinder and a piston slidably disposed within the cylinder and interlocked with the throttle valve. The pressure variation in the variable volume chamber according to operation of the throttle valve for acceleration or deceleration of the engine is transmitted to either the pressure difference control unit or the air valve control unit to correct the preset pressure difference across the fuel metering valve or the preset pressure in the air pressure chamber, whereby the air-fuel ratio is made richer or leaner during acceleration or deceleration of the engine.