Closed-loop mixture controlled fuel injection system

Claim 2

A mixture control system for an internal combustion engine, comprising: first means for detecting the pressure of air inducted to said engine; second means for detecting the speed of said engine; third means for detecting the concentration of a predetermined composition of exhaust emissions from said engine, said concentration varying as a function of the air-fuel ratio of a mixture supplied to said engine; a memory having a plurality of storage locations; control means effective to determine the optimum value of the air-fuel ratio of a mixture to be inducted to said engine, said control means including means for: (a) deriving a basic quantity of fuel to be injected to said engine as a function of the detected pressure and engine speed, (b) deriving a first trimming value as a function of the detected concentration, (c) determining a second trimming value as a function of one of a plurality of ranges of different engine speed values to which the detected engine speed belongs, (d) correcting said second trimming value dependant on said first trimming value, (e) storing the corrected second trimming value into a storage location of said memory exclusively addressable as a function of the detected engine speed, (f) reading the stored second trimming value as a function of the detected engine speed from said memory, and (g) trimming said basic quantity by adding thereto the read second trimming value; and means for injecting fuel to said engine in response to the trimmed quantity.

Claim 3

A system as claimed in claim 1, wherein said memory is of a nonvolatile type.

Claim 4

A system as claimed in claim 1, wherein said storage locations of said memory are addressable as a function of an engine speed value, said memory storing second trimming values one of which corresponds to one of a plurality of ranges of different engine speed values, and wherein said control means is arranged to successively detect to which one of said ranges the detected engine speed belongs in order to successively determine one of the stored second trimming values corresponding to the detected engine speed value, said stored second trimming values being corrected in dependance on said first trimming value, said first trimming value being corrected in accordance with the output state of said third means.

Claim 5

A system as claimed in claim 3, wherein control means is arranged to accumulate said first trimming value, derive an average value of the accumulated first trimming values and trim said stored second trimming value by a predetermined amount in a direction depending on said average value.

Claim 6

A mixture control system for an internal combustion engine, comprising: first means for detecting the pressure of air inducted to said engine; second means for detecting the speed of said engine; third means for detecting the concentration of a predetermined constituent of exhaust gases from said engine, said concentration varying as a function of the air-fuel ratio of a mixture supplied to said engine; a memory having a plurality of storage locations; data processing means programmed to perform the step of: (a) deriving a basic quantity of fuel to be injected to said engine as a function of the detected pressure and engine speed; (b) deriving a first trimming value as a function of the detected concentration; (c) repeating the step (b) a number of predetermined times to derive an average value of the derived first trimming values; (d) determining a second trimming value as a function of one of a plurality of ranges of different engine speed values to which the detected engine speed belongs; (e) correcting said second trimming value according to said average value; storing the corrected second trimming value into a storage location of said memory exclusively addressable as a function of the detected engine speed; (g) reading the stored second trimming value as a function of the detected engine speed from said memory; (h) trimming said basic quantity by adding thereto the read second trimming value; and (i) further trimming the trimmed basic quantity by multiplying said average value of derived first trimming values thereby; and means for injecting fuel to said engine in response to the basic quantity trimmed in the step (i).

Claim 7

A mixture control system for an internal combustion engine, comprising: first means for detecting the pressure of air inducted to said engine; second means for detecting the speed of said engine; third means for detecting the concentration of a predetermined constituent of exhaust gases from said engine, said concentration varying as a function of the air-fuel ratio of a mixture supplied to said engine; a memory having a plurality of storage locations; data processing means programmed to perform the step of: (a) deriving a basic quantity of fuel to be injected to said engine as a function of the detected pressure and engine speed; (b) deriving a first trimming value as a function of the detected concentration; (c) repeating the step (b) a number of predetermined times to derive an average value of the derived first trimming values; (d) determining a second trimming value as a function of one of a plurality of ranges of different engine speed values to which the detected engine speed belongs; (e) correcting said second trimming value according to said average value; storing the corrected second trimming value into a storage location of said memory exclusively addressable as a function of the detected engine speed; (g) reading the stored second trimming value as a function of the detected engine speed from said memory; (h) trimming said basic quantity by adding thereto the read second trimming value; and (i) further trimming the trimmed basic quantity by multiplying said average value of derived first trimming values thereby; and means for injecting fuel to said engine in response to the basic quantity trimmed in the step (i).

Claim 8

A system as claimed in claim 5, wherein said memory is of a nonvolatile type.

Claim 9

A system as claimed in claim 5, wherein said storage locations of said memory are addressable as a function of an engine speed value, said memory storing second trimming values one of which corresponds to one of a plurality of ranges of different engine speed values, and wherein said data processing means is further programmed to perform the steps of: (A) successively detecting to which one of said ranges the detected engine speed belongs; (B) detecting a match between the successively detected ranges; and (C) correcting the stored second trimming value in dependance on said first trimming value in response to said match being detected.

Claim 10

A system as claimed in claim 7, wherein data processing means is further programmed to perform the steps of: accumulating said first trimming value; deriving an average value of the accumulated first trimming values; and wherein in the step (C) the stored second trimming value is trimmed by a predetermined amount in a direction depending on said average value of the first trimming values.