Method of and apparatus for controlling an air ratio of the air-fuel mixture supplied to an internal combustion engine

Claim 3

A method as claimed in claim 1, wherein said first value is larger than said second value.

Claim 4

A method as claimed in claim 2, wherein said first value and said second value are fixed values.

Claim 5

A method as claimed in claim 2, wherein said first value and said second value are changed in accordance with the length of said time elapsed.

Claim 6

A method as claimed in claim 4, wherein said predetermined time comprises a first fixed time and a second fixed time, which is shorter than said first fixed time, said first value comprising a primary fixed value and a secondary fixed value, which is smaller than said primary fixed value, the level of the injection control signal being incrementally changed by said primary fixed value when said time elapsed is shorter than said first fixed time, but is not shorter than said second first fixed time, but is not shorter than said second fixed time, the level of the injection control signal being incrementally changed by said secondary fixed value when said time elapsed is shorter than said second fixed time.

Claim 7

A method as claimed in claim 4, wherein said predetermined time comprises a first fixed time and a second fixed time, which is shorter than said first fixed time, said second value comprising a primary fixed value and a secondary fixed value which is larger than said primary fixed value, the level of the injection control signal being incrementally changed by said primary fixed value when said time elapsed is shorter than said first fixed time, but is not shorter than said second fixed time, the level of the injection control signal being incrementally changed by said secondary fixed value when said time elapsed is shorter than said second fixed time.

Claim 8

A method as claimed in claim 1, wherein the level of the injection control signal is gradually increased and reduced during the time the oxygen concentration detector issues the rich signal and the lean signal, respectively.

Claim 9

Apparatus for controlling a ratio of the air-fuel mixtures fed into cylinders of an internal combustion engine comprising: a fuel injector arranged in an intake passage of said engine; an oxygen concentration detector arranged in an exhaust passage of the engine for issuing a rich signal and a lean signal which indicate that the air-fuel ratio of a mixture supplied to said engine is on the rich side and on the lean side of the stoichiometric air-fuel ratio, respectively; and an electronic control means, responsive to said oxygen concentration detector for converting said rich and lean signals to an injection control signal having a level which is proportional to the injection time period of the fuel injector, said electronic control means also for: (1) incrementally increasing by a predetermined first value the level of said injection control signal when the signal of said oxygen concentration detector changes from the rich signal to the lean signal, (2) incrementally decreasing by a predetermined second value which is different from the first value said injection control signal when the signal of the oxygen concentration detector changes from the lean signal to the rich signal, (3) detecting a change in the output of the oxygen concentration detector between the rich and lean signals, (4) measuring the time elapsed from one change to a next change of said oxygen concentration detector output, (5) comparing said time elapsed with a predetermined time, and (6) changing the level of the injection control signal by a value which is equal to the value of the incremental change of said injection control signal in response to the preceding change of the signal of the oxygen concentration detector when said time elapsed is shorter than said predetermined time.

Claim 10

Apparatus for controlling a ratio of the air-fuel mixtures fed into cylinders of an internal combustion engine comprising: a fuel injector arranged in an intake passage of said engine; an oxygen concentration detector arranged in an exhaust passage of the engine for issuing a rich signal and a lean signal which indicate that the air-fuel ratio of a mixture supplied to said engine is on the rich side and on the lean side of the stoichiometric air-fuel ratio, respectively; and an electronic control means, responsive to said oxygen concentration detector for converting said rich and lean signals to an injection control signal having a level which is proportional to the injection time period of the fuel injector, said electronic control means also for: (1) incrementally increasing by a predetermined first value the level of said injection control signal when the signal of said oxygen concentration detector changes from the rich signal to the lean signal, (2) incrementally decreasing by a predetermined second value which is different from the first value said injection control signal when the signal of the oxygen concentration detector changes from the lean signal to the rich signal, (3) detecting a change in the output of the oxygen concentration detector between the rich and lean signals, (4) measuring the time elapsed from one change to a next change of said oxygen concentration detector output, (5) comparing said time elapsed with a predetermined time, and (6) changing the level of the injection control signal by a value which is equal to the value of the incremental change of said injection control signal in response to the preceding change of the signal of the oxygen concentration detector when said time elapsed is shorter than said predetermined time.

Claim 11

Apparatus as in claim 8, wherein said first value is larger than said second value.

Claim 12

Apparatus as in claim 9, wherein said first value and said second value are fixed values.

Claim 13

A method as claimed in claim 9, wherein said electronic control means changes said first and second values in accordance with the length of said time elapsed.

Claim 14

Apparatus as claimed in claim 11, wherein said predetermined time comprises a first fixed time and a second fixed time, which is shorter than said first fixed time, and said first value comprises a primary fixed value and a secondary fixed value, which is smaller than said primary fixed value, said electronic control means incrementally changing the level of said injection control signal by said primary fixed value when said time elapsed is shorter than said first fixed time, but is not shorter than said second fixed time and incrementally changing the level of said injection control signal by said secondary fixed time when said elapsed time is shorter said second fixed time.

Claim 15

Apparatus as claimed in claim 11, wherein said predetermined time comprises a first fixed time and a second fixed time, which is shorter than said first fixed time, and said second value comprises a primary fixed value and a secondary fixed value which is smaller than said primary fixed value, said electronic control means incrementally changing the level of said injection control signal by said primary fixed value when said time elapsed is shorter than said first fixed time, but is not shorter than said second fixed time, and incrementally changing the level of said injection control signal by said secondary fixed value when said elapsed time is shorter said second fixed time.

Claim 16

Apparatus as claimed in claim 8, wherein said electronic control means gradually increases and decreases the level of said injection control signal during the time the oxygen concentration detector issues the rich signal and the lean signal, respectively.