Fuel injection apparatus for internal combustion engines

Claim 2

A fuel injection apparatus for internal combustion engine comprising: an air bypass for communicating the upstream side of a Venturi portion formed in an air-intake path with the Venturi portion; an air flow sensor provided in the middle of said air bypass; an air-scaling valve provided in said air bypass so as to control the amount of air flow in said air bypass; a level setting means for producing a set level value which is smaller than a maximum output value of said air flow sensor occuring when said air-scaling valve is fully opened during idling operation of the engine; a discriminating means for comparing and discriminating the set level produced from said level setting means and an output of said air flow sensor; a control signal generating means responsive to a discrimination signal from said discriminating means, for generating a control signal which controls said air-scaling valve so that the output of said air flow sensor converges to said set level; and a fuel control means responsive to the control signal, for controlling fuel fed from a fuel supply means.

Claim 3

A fuel injection apparatus for internal combustion engine according to claim 1 wherein the discrimination signal from said discriminating means is converted into a duty pulse by said control signal generating means.

Claim 4

A fuel injecton apparatus for internal combustion engine according to claim 2 wherein said air flow sensor comprises a heat-type flow sensor.

Claim 5

A fuel injection apparatus for internal combustion engine according to claim 3 wherein the signal of said heat-type flow sensor and the set level are produced in the form of voltages which are compared by a differential amplifier to produce the discrimination signal.

Claim 6

A fuel injection apparatus for internal combustion engine comprising: an air-intake path connected to the upstream side of an air-intake tube meeting portion; a Venturi portion formed in said air-intake path; a throttle valve provided in said air-intake path on the downstream side of said Venturi portion; an air bypass for connecting the upstream side of said Venturi portion and said Venturi portion; an air flow meter provided in said air bypass so as to detect the amount of air flow in said air bypass; an air-scaling valve provided in said air bypass; a fuel path through which fuel from a fuel pump is continuously fed into said air-intake path when the internal combustion engine is operating; a fuel-scaling valve provided in said fuel path; a drive means for controlling the degree to which said air-scaling valve and said fuel-scaling valve are opened, so that when said air-scaling valve is displaced to decrease the amount of air flow in said air bypass, said fuel-scaling valve is displaced to increase fuel; a level setting means for producing a set level value which is smaller than a maximum output value of said air flow meter occurring when said air-scaling valve is fully opened during idling operation of the engine; a discriminating means for comparing and discriminating the set level produced from said level setting means and an output of said air flow meter; and a control signal generating means responsive to a discrimination signal from said discriminating means, for applying a control signal to said drive means so as to control the degree of opening of said air-scaling valve so that the output of said air flow meter converges to said set level.

Claim 7

A fuel injection apparatus for internal combustion engine comprising: an air-intake path connected to the upstream side of an air-intake tube meeting portion; a Venturi portion formed in said air-intake path; a throttle valve provided in said air-intake path on the downstream side of said Venturi portion; an air bypass for connecting the upstream side of said Venturi portion and said Venturi portion; an air flow meter provided in said air bypass so as to detect the amount of air flow in said air bypass; an air-scaling valve provided in said air bypass; a fuel path through which fuel from a fuel pump is continuously fed into said air-intake path when the internal combustion engine is operating; a fuel-scaling valve provided in said fuel path; a drive means for controlling the degree to which said air-scaling valve and said fuel-scaling valve are opened, so that when said air-scaling valve is displaced to decrease the amount of air flow in said air bypass, said fuel-scaling valve is displaced to increase fuel; a level setting means for producing a set level value which is smaller than a maximum output value of said air flow meter occurring when said air-scaling valve is fully opened during idling operation of the engine; a discriminating means for comparing and discriminating the set level produced from said level setting means and an output of said air flow meter; and a control signal generating means responsive to a discrimination signal from said discriminating means, for applying a control signal to said drive means so as to control the degree of opening of said air-scaling valve so that the output of said air flow meter converges to said set level.