Method and device for learn-controlling the air-fuel ratio of an internal combustion engine

Claim 2

Method for learn-controlling the air-fuel ration of an internal combustion engine, comprising the method steps of: -detecting an engine running condition (a, N, Q) including at least one parameter concerning the intake air quantity (Q), -determining a basic fuel injection quantity (Tp) based on the detected engine running condition (a, N, Q), -detecting the air-fuel ratio based on a component (Qz) of the exhaust gas, -determining a feedback correction coefficient (LAMDA) by comparing the air-fuel ratio with a target air-fuel ratio, -determining areal learning correction coefficients (K MAP ) for respective operational areas (N, Tp) of the engine based on the feedback correcting coefficient (LAMDA) concering the respective operational area (N, Tp), and -calculating a fuel injection quantity based on the basic fuel injection quantity (Tp), the feedback correction coefficient (LAMDA) and one of the areal learning correction coefficients (K MAP ) belonging to the actual operational area (M. Tp), characterized by the method steps of: -determining whether or not all areal learning correction coefficients (K MAP ) have the same sign, tendency or direction of deviation, --if this condition is fulfilled, calculating a common value (X) of the areal learning correction coefficients (K MAP ), --determining a global learning correction coefficient (K ALT ) for all operational areas (N, Tp)of the engine based on the common value (X), wherein the calculation of the fuel injection quantity is also based on the global learning correction coefficients (K ALT ), and --calculating new areal learning correction coefficients (K MAP ) based on the common value (X) and previous areal learning correction coefficients (K MAP ).

Claim 3

Method as claimed in claim 1, characterized in that said common value is a mean value (X) or a minimum value (X) of the areal learning correction coefficients (K MAP ).

Claim 4

Method as claimed in claim 1 or 2, characterized in that the method step of determining the areal correction coefficient (K MAP ) comprises the determination of a deviation of the feedback correction coefficient (LAMDA) from a reference value for each operational area (N, Tp) and correcting a previous areal correction coefficient (K MAP ) so that the deviation is minimized.

Claim 5

Method as claimed in one of claims 1 to 3, characterized in that the method step of determining the sign or tendency or direction of deviations of the areal learning correction coefficients (K MAP ), calculating the common value (X), determining the global learning correction coefficient (K ALT ) and calculating new areal learning correction coefficients (K MAP ) comprise: -issuing a first global learning command (S101 ) every time the areal learning correction coefficients (K MAP ) for a predetermined number of operational areas (N, Tp) are corrected, -judging the tendency or sign or direction of deviations of the present areal learning correction coefficients (K MAP ) from a reference value for a predetermined number of different operational areas (N, Tp) when the first global learning command is issued, -issuing a second global learning command (S107, YES) when all the deviations have the same tendency or sign or direction, -calculating a mean or minimum value (X) of deviations of the present areal learning correction coefficients (K MAP ) from the reference value for the predetermined number of operational areas when the second global learning command is issued, -correcting (S110) the global learning correction coefficient (K ALT ) by adding the mean or minimum value to the global learning correction coefficient (K ALT ), and -correcting (S111) the areal learning correction coefficients (K MAP ) by subtracting the mean or minimum value (X) from the previous areal learning correction coefficients (K MAP ).

Claim 6

Method as claimed in one of claims 1 to 4, characterized in that the method step of determining the areal learning correction coefficients (K MAP ) comprises: -checking (S81) whether or not the operational area (N, Tp) is the same one as in a previous checking routine, -if so, counting the number (C MAP ) of inversions of a signal representing the component (0 2 ) of the exhaust gas, -determining a lower (LAMDA 2) and an upper (LAMDA 1) feedback correction coefficient (LAMDA) at predetermined counts (C MAP ) = 3; CMAP ≧4). -calculating the new areal learning correction coefficients (K MAP ) based on a previous one (K MAP ) and the mean value ( ALAMD A ) of said lower and upper feedback correction coefficients (LAMDA 1, LAMDA 2).

Claim 7

Device for learn-controlling the air-fuel ratio of an internal commbustion engine, comprising: -engine running condition detecting means (A) for detecting at least one parameter (a,N, Q) concering the intake air quantity (Q), -basic fuel injection quantitiy setting means (G) for setting a fuel injection quantity (Tp) based on the detected engine running condition (a, N, Q), -an exhaust gas sensor (B) for detecting the air-fuel ratio based on a component (0 2 ) of the exhaust gas, -feedback correction coefficient setting means (G) for comparing the air-fuel ratio with a target air-fuel ratio, -areal learning correctng coefficient correcting means (J) for determining areal learning correction coefficients (K MAP ) for respective operational areas (N, Tp) of the engine based on the feedback correction coefficient (LAMDA) concerning the respective operational area (N, Tp), and -fuel injection quantity calculating means (H) for calculating a fuel injection quantity based on the basic fuel injection quantity (Tp), the feedback correction coefficient (LAMDA) and one of the areal learning correction coefficients (MAP) belonging to the actual operational area (N, Tp) characterized by -judging means (K, L) for determining whether or not all areal learning correction coefficients (K MAP ) have the same sign or tendency or direction of deviation, -calculating means (M) responsive to the judging means (K, L) for calculating an common value (X) of the areal learning correction coefficients (K MAP ), -global learning correction coefficient setting means (N, D) for determining a glabal learning correction coefficient (K ALT ) for all operational areas (N, Tp) of the engine based on the common value (X), wherein said fuel injection quantity calculating means (H) is arranged to calculate the fuel injection quantity also on the basis of said global learning correction coefficient (K ALT ) and -areal learning correction coefficient correcting means (0) for calculating new areal learning correction coefficients (K MAP ) based on the common value (X) and previous areal learning correction coefficients (K MAP ).

Claim 8

Device for learn-controlling the air-fuel ratio of an internal commbustion engine, comprising: -engine running condition detecting means (A) for detecting at least one parameter (a,N, Q) concering the intake air quantity (Q), -basic fuel injection quantitiy setting means (G) for setting a fuel injection quantity (Tp) based on the detected engine running condition (a, N, Q), -an exhaust gas sensor (B) for detecting the air-fuel ratio based on a component (0 2 ) of the exhaust gas, -feedback correction coefficient setting means (G) for comparing the air-fuel ratio with a target air-fuel ratio, -areal learning correctng coefficient correcting means (J) for determining areal learning correction coefficients (K MAP ) for respective operational areas (N, Tp) of the engine based on the feedback correction coefficient (LAMDA) concerning the respective operational area (N, Tp), and -fuel injection quantity calculating means (H) for calculating a fuel injection quantity based on the basic fuel injection quantity (Tp), the feedback correction coefficient (LAMDA) and one of the areal learning correction coefficients (MAP) belonging to the actual operational area (N, Tp) characterized by -judging means (K, L) for determining whether or not all areal learning correction coefficients (K MAP ) have the same sign or tendency or direction of deviation, -calculating means (M) responsive to the judging means (K, L) for calculating an common value (X) of the areal learning correction coefficients (K MAP ), -global learning correction coefficient setting means (N, D) for determining a glabal learning correction coefficient (K ALT ) for all operational areas (N, Tp) of the engine based on the common value (X), wherein said fuel injection quantity calculating means (H) is arranged to calculate the fuel injection quantity also on the basis of said global learning correction coefficient (K ALT ) and -areal learning correction coefficient correcting means (0) for calculating new areal learning correction coefficients (K MAP ) based on the common value (X) and previous areal learning correction coefficients (K MAP ).