Fuel supply apparatus for internal combustion engines

Abstract

A fuel supply apparatus for an internal combustion engines comprises a throttle valve disposed in an intake conduit leading to the internal combustion engine, an air valve disposed in the intake conduit upstream of the throttle valve so as to define an air pressure chamber in the intake conduit in cooperation with the throttle valve, a device for controlling the air valve in response to the pressure prevailing in the air pressure chamber so that the pressure be maintained at a substantially constant level, and a fuel metering device including a variable throttle passage provided in a fuel feed conduit opening in the intake conduit through a fuel injection valve and interlocked with the air valve to be controlled so that the flow section area of the throttle passage may be proportional to the opening degree of the air valve, and a device for maintaining difference in pressure produced across the variable throttle passage at a predetermined value. The air valve controlling device includes a feedback control system which comprises a device for producing a signal of a level corresponding to the pressure prevailing in the air pressure chamber in the intake conduit, and a device responding to the signal for controlling the air valve so that the pressure within the air pressure chamber be maintained at a set valve, and further includes a device for automatically changing the level of the signal representative of the pressure level in the air pressure chamber in dependence on the environmental and operating conditions of the engine such as embient temperature, atmospheric pressure, engine temperature, deceleration and acceleration of the engine and the like, thereby to vary the intake air quantity to attain an optimum air-fuel ratio for the instantaneous operating condition of the engine.