Fuel supply control method for internal combustion engines

Claim 1

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold and upstream of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel in an amount responsive to said predetermined low load condition to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; and (c) supplying fuel to said cylinders through both said first and second fuel injection valves when said engine is determined to be operating in an operating condition other than said predetermined low load condition in a manner such that (1) said second fuel injection valve supplies a first amount of fuel which is required for said operating condition other than said predetermined low load condition and (2) said first fuel injection valve supplies a second amount of fuel which compensates for a portion of said first amount of fuel supplied by said second injection valve which portion is not immediately and directly supplied to said cylinders.

Claim 2

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold and upstream of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel in an amount responsive to said predetermined low load condition to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; and (c) supplying fuel to said cylinders through both said first and second fuel injection valves when said engine is determined to be operating in an operating condition other than said predetermined low load condition in a manner such that (1) said second fuel injection valve supplies a first amount of fuel which is required for said operating condition other than said predetermined low load condition and (2) said first fuel injection valve supplies a second amount of fuel which compensates for a portion of said first amount of fuel supplied by said second injection valve which portion is not immediately and directly supplied to said cylinders.

Claim 9

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold but axially different from the location of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; (c) supplying fuel to said cylinders through both said first and second fuel injection valves, when said engine is determined to be operating in an operating condition other than said predetermined low load condition; and (d) determining fuel injection periods of said first and second fuel injection valves on the basis of operating parameters of said engine and in synchronism with a signal generated at predetermined crank angles of said engine, measuring a time interval of generation of said signal when said engine is operating in said operating condition other than said predetermined low load condition, comparing a period of time corresponding to the measured time interval of generation of said signal with the determined fuel injection period of said second fuel injection valve, and when the latter is longer than the former, supplying a quantity of fuel corresponding to a difference between the two periods of time to said cylinders through said first fuel injection valve and at the same time supplying a quantity of fuel corresponding to the measured time interval of generation of said signal to said cylinders through said second fuel injection valve, wherein said period of time corresponding to the time interval of generation of said signal is a difference between the measured time interval of generation of said signal and a period of time required for said second fuel injection valve to become completely shut from an open state thereof.

Claim 10

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold but axially different from the location of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; (c) supplying fuel to said cylinders through both said first and second fuel injection valves, when said engine is determined to be operating in an operating condition other than said predetermined low load condition; and (d) determining fuel injection periods of said first and second fuel injection valves on the basis of operating parameters of said engine and in synchronism with a signal generated at predetermined crank angles of said engine, measuring a time interval of generation of said signal when said engine is operating in said operating condition other than said predetermined low load condition, comparing a period of time corresponding to the measured time interval of generation of said signal with the determined fuel injection period of said second fuel injection valve, and when the latter is longer than the former, supplying a quantity of fuel corresponding to a difference between the two periods of time to said cylinders through said first fuel injection valve and at the same time supplying a quantity of fuel corresponding to the measured time interval of generation of said signal to said cylinders through said second fuel injection valve, wherein said period of time corresponding to the time interval of generation of said signal is a difference between the measured time interval of generation of said signal and a period of time required for said second fuel injection valve to become completely shut from an open state thereof.

Claim 11

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold but axially different from the location of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; (c) determining fuel injection periods of said first and second fuel injection valves respectively on the basis of operating parameters of said engine and in synchronism with a signal generated at predetermined crank angles of said engine, so that fuel may be supplied to said cylinders through both said first and second fuel injection valves when said engine is determined to be operating in an operating condition other than said predetermined low level condition; (d) measuring a time interval of generation of said signal; (e) comparing a period of time corresponding to the measured time interval of generation of said signal with the determined fuel injection period of said second fuel injection valve; and (f) when the latter is longer than the former, supplying a quantity of fuel corresponding to a difference between the two periods of time to said cylinders through said first fuel injection valve and at the same time supplying a quantity of fuel corresponding to the measured time interval of generation of said signal to said cylinders through said second fuel injection valve.

Claim 12

A method of controlling the supply of fuel to an internal combustion engine having a plurality of cylinders, an intake passage having an intake manifold connected to said cylinders, a throttle valve arranged in said intake passage at a location upstream of said intake manifold, at least one first fuel injection valve arranged in said intake passage at a location upstream of said intake manifold, and at least one second fuel injection valve arranged in said intake passage at a location upstream of said intake manifold but axially different from the location of said first fuel injection valve, wherein said first and second fuel injection valves are selectively operated to supply fuel to said cylinders in dependence on operating conditions of said engine, the method comprising the steps of: (a) determining whether or not said engine is operating in a predetermined low load condition; (b) supplying fuel to said cylinders through said first fuel injection valve alone, when said engine is determined to be operating in said predetermined low load condition; (c) determining fuel injection periods of said first and second fuel injection valves respectively on the basis of operating parameters of said engine and in synchronism with a signal generated at predetermined crank angles of said engine, so that fuel may be supplied to said cylinders through both said first and second fuel injection valves when said engine is determined to be operating in an operating condition other than said predetermined low level condition; (d) measuring a time interval of generation of said signal; (e) comparing a period of time corresponding to the measured time interval of generation of said signal with the determined fuel injection period of said second fuel injection valve; and (f) when the latter is longer than the former, supplying a quantity of fuel corresponding to a difference between the two periods of time to said cylinders through said first fuel injection valve and at the same time supplying a quantity of fuel corresponding to the measured time interval of generation of said signal to said cylinders through said second fuel injection valve.