Fuel feeding apparatus for internal combustion engine

Claim 1

A fuel feeding apparatus for an internal combustion engine comprising; (a) a main intake air path connected to an upstream side of a manifold portion of intake pipes; (b) a Venturi portion formed in said main air-intake path; (c) a throttle valve disposed in said main air-intake path at a position downstream of said Venturi portion; (d) a bypass air path disposed adjacent to said main air-intake path to supply bypass air from a point upstream of said Venturi portion to said Venturi portion; (e) an air flow meter disposed in said bypass air path to detect the quantity of air flowing through said bypass air path; (f) an air-metering valve disposed in said bypass air path at a position downstream of said air flow meter; (g) a fuel path feeding fuel continuously from a fuel pump into said main air-intake path during operation of the engine; (h) a fuel-metering valve disposed in said fuel path; (i) drive means for controlling the opening of said air-metering valve and said fuel-metering valve in such a manner that said fuel-metering valve is displaced to increase the quantity of fuel flowing through said fuel path when said air-metering valve is displaced to decrease the quantity of air flowing through said bypass air path; (j) control signal generating means applying a control signal to said drive means for controlling the opening of said air-metering valve so that the output signal of said air flow meter attains coincidence with a pre-set level; (k) an oxygen sensor disposed in an engine exhaust gas path; and (l) closed-loop control means for modifying the value of said pre-set level in response to the output signal of said oxygen sensor so that the rate of excess air in the engine exhaust gases can be maintained to be always equal to unity.