Method and apparatus for controlling ignition timing in a multicylinder internal combustion engine

Claim 3

A method as claimed in claim 1, wherein said value derived in said step (f) is a sum of absolute values of said differences.

Claim 4

A method as claimed in claim 1, wherein said value derived in said step (f) is an average value of said differences.

Claim 5

A method as claimed in claim 1, wherein said predetermined relationship in said steps (h) and (i) is such that said value is greater than or equal to said predetermined value.

Claim 6

A method as claimed in claim 4, wherein said predetermined value is selected so as to represent an engine operating condition where the ignition timing combination is close to an optimum igntionin timing combination at which maximum engine output can be derived.

Claim 7

A method as claimed in claim 1, wherein said predetermined relationship in said steps (h) and (i) is such that said value is smaller than or equal to said predetermined value.

Claim 8

A method as claimed in claim 6, wherein said predetermined value is selected so as to represent an engine operating condition which has been disturbed drastically.

Claim 9

A method as claimed in claim 1, wherein said step of replacing comprising the steps of: calculating an average ignition timing θ throughout said various combinations; and calculating said new combination θ new in accordance with the following equation: θ.sub.new =θ-α(θ.sub.min -θ) wherein α is a constant; and θ min is the ignition timing combination giving the largest negative difference or the lowest engine output in the case that all the differences are positive.

Claim 10

A method as claimed in claim 1, wherein the number of said plurality of ignition timing combinations equals the number of cylinders of said engine plus one.

Claim 11

A method as claimed in claim 1, wherein said engine output is engine speed.

Claim 12

Apparatus for controlling ignition timing in a multicylinder internal combustion engine, comprising: (a) first means for producing ignition signals which are respectively fed to spark plugs of the engine cylinders, said first means being capable of producing said ignition signals having different timings from another; (b) second means for detecting the engine output; (c) third means for detecting engine parameters; and (d) fourth means responsive to said second and third means for causing said first means to produce said ignition signals, said fourth means; determining a basic ignition timing in view of said engine parameters; changing said basic ignition timing so that various combinations of ignition timings are provided for operating said engine with said various ingition timing combinations in such a manner that said engine is operated twice with an identical ignition timing combination; deriving the difference between the engine output data both obtained from engine operation in twice with said identical ignition timing combination; deriving, by using said difference, imaginary engine output data which would have been obtained if the engine were operated with said identical ignition timing combination with which said engine has been operated twice; deriving the difference between each imaginary engine output and each engine output data actually measured; deriving a value indicative of the variation throughout the differences each between imaginary engine output data and actually measured data; comparing said value with a predetermined value; replacing the ignition timing combination, which gives the largest negative difference or the lowest engine output in the case that all the differences are positive, with a new ignition timing combination when said value has a predetermined relationship with said predetermined value; and determining a subsequent ignition timing by using one of said plurality of ignition timings when said value does not have said predetermined relationship with said predetermined value.

Claim 13

Apparatus for controlling ignition timing in a multicylinder internal combustion engine, comprising: (a) first means for producing ignition signals which are respectively fed to spark plugs of the engine cylinders, said first means being capable of producing said ignition signals having different timings from another; (b) second means for detecting the engine output; (c) third means for detecting engine parameters; and (d) fourth means responsive to said second and third means for causing said first means to produce said ignition signals, said fourth means; determining a basic ignition timing in view of said engine parameters; changing said basic ignition timing so that various combinations of ignition timings are provided for operating said engine with said various ingition timing combinations in such a manner that said engine is operated twice with an identical ignition timing combination; deriving the difference between the engine output data both obtained from engine operation in twice with said identical ignition timing combination; deriving, by using said difference, imaginary engine output data which would have been obtained if the engine were operated with said identical ignition timing combination with which said engine has been operated twice; deriving the difference between each imaginary engine output and each engine output data actually measured; deriving a value indicative of the variation throughout the differences each between imaginary engine output data and actually measured data; comparing said value with a predetermined value; replacing the ignition timing combination, which gives the largest negative difference or the lowest engine output in the case that all the differences are positive, with a new ignition timing combination when said value has a predetermined relationship with said predetermined value; and determining a subsequent ignition timing by using one of said plurality of ignition timings when said value does not have said predetermined relationship with said predetermined value.

Claim 14

Apparatus as claimed in claim 11, wherein said second means comprises a pulse generator producing a pulse train indicative of the engine speed.

Claim 15

Apparatus as claimed in claim 11, wherein said fourth means comprises a computer having a processor and a memory in which ignition timing data are stored, said computer being arranged to execute an interrupt service routine in response to an interrupt request repeatedly generated.

Claim 16

Apparatus as claimed in claim 13, wherein said computer comprises means for counting the number of said various combinations so that one of said combinations giving the largest negative difference or the lowest engine ouput is detected when said engine is operated with a predetermined number of said various combinations.