US4627404A — Method and apparatus for controlling air-fuel rat…

Claim 1

Independent Claim 135 words

A method for controlling the air-fuel ratio in an internal combustion engine comprising the steps of: calculating a base fuel amount in accordance with first predetermined engine operating parameters; determining whether or not said engine is in a transient state; detecting an air-fuel ratio deviation from the optimum air-fuel ratio for each of a plurality of regions, said regions being defined by predetermined ranges of values of a second engine operating parameter, said detecting only occurring when said engine is in a transient state; calculating a transient fuel correction amount in accordance with said detected air-fuel ratio deviation for each region as defined by said second engine operating parameter; and calculating a fuel amount to be supplied to said engine by correcting said base fuel amount in accordance with said calculated transient fuel correction amount.

Claim 2

Independent Claim 135 words

A method for controlling the air-fuel ratio in an internal combustion engine comprising the steps of: calculating a base fuel amount in accordance with first predetermined engine operating parameters; determining whether or not said engine is in a transient state; detecting an air-fuel ratio deviation from the optimum air-fuel ratio for each of a plurality of regions, said regions being defined by predetermined ranges of values of a second engine operating parameter, said detecting only occurring when said engine is in a transient state; calculating a transient fuel correction amount in accordance with said detected air-fuel ratio deviation for each region as defined by said second engine operating parameter; and calculating a fuel amount to be supplied to said engine by correcting said base fuel amount in accordance with said calculated transient fuel correction amount.

Claim 3

Dependent Claim 27 words

A method as set forth in claim 1, wherein said first predetermined engine operating parameters are the intake air amount and the rotational speed of said engine.

Claim 4

Dependent Claim 27 words

A method as set forth in claim 1, wherein said first predetermined engine operating parameters are the intake air pressure and the rotational speed of said engine.

Claim 5

Dependent Claim 88 words

A method as set forth in claim 1, wherein said transient state determining step comprises the steps of: determining whether or not the engine coolant temperature is lower than a predetermined value; determining whether or not a predetermined time period has passed after initiation of acceleration; determining whether or not the rotational speed of said engine is within a predetermined range; and determining whether or not an air-fuel ratio feedback control operation is carried out, whereby said transient state is established only when all said determinations are affirmative.

Claim 6

Dependent Claim 51 words

A method as set forth in claim 1, wherein said air-fuel ratio deviation detecting step comprises the steps of: calculating a lean state duration for each region determined by said second predetermined engine operating parameter; and calculating a rich state duration for each region determined by said second predetermined engine parameter.

Claim 7

Dependent Claim 19 words

A method as set forth in claim 1, wherein said second engine operating parameter is the engine coolant temperature.

Claim 8

Dependent Claim 22 words

A method as set forth in claim 1, wherein said second engine operating parameter is the intake air amount of said engine.

Claim 9

Dependent Claim 21 words

A method as set forth in claim 1, wherein said second engine operating parameter is the throttle opening of said engine.

Claim 10

Dependent Claim 21 words

A method as set forth in claim 1, wherein said second engine operating parameter is the rotational speed of said engine.

Claim 11

Dependent Claim 83 words

A method as set forth in claim 5, wherein said transient fuel correction amount calculating step calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{Q/N-(Q/N).sub.i }×C.sub.a ×K where Q is the intake air amount of said engine; N is the rotational speed of said engine; (Q/N) i is a blunt value of Q/N; C a is a coefficient determined by said maximum lean state duration and maximum rich state duration; and K is a coefficient determined by the coolant temperature of said engine.

Claim 12

Dependent Claim 51 words

A method as set forth in claim 10, wherein said blunt value (Q/N) i is calculated by (Q/N).sub.i ←(Q/N).sub.i-1 +{Q/N-(Q/N).sub.i-1 }/C.sub.b where (Q/N) i-1 is a blunt value of Q/N calculated at a previous cycle; and C b is a coefficient determined by said lean state duration and rich state duration.

Claim 13

Dependent Claim 79 words

A method as set forth in claim 5, wherein said transient fuel correction amount calculating step calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{PM-(PM).sub.i }×C.sub.a ×K where PM is the intake air pressure of said engine; N is the rotational speed of said engine; (PM) i is a blunt value of PM; C a is a coefficient determined by said lean state duration and rich state duration; and K is a coefficient determined by the engine coolant temperature.

Claim 14

Dependent Claim 51 words

A method as set forth in claim 12, wherein said blunt value (PM) i is calculated by (PM).sub.i ←(PM).sub.i-1 +{PM-(PM).sub.i-1 }/C.sub.b where (PM) i-1 is a blunt value of PM calculated at a previous cycle; and C b is a coefficient determined by said lean state duration and rich state duration.

Claim 15

Dependent Claim 78 words

A method as set forth in claim 5, wherein said transient fuel correction amount calculating step calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{TH-(TH).sub.i }×C.sub.a ×K where TH is the throttle opening of said engine; N is the rotational speed of said engine; (TH) i is a blunt value of TH; C a is a coefficient determined by said lean state duration and rich state duration; and K is a coefficient determined by the engine coolant temperature.

Claim 16

Dependent Claim 53 words

A method as set forth in claim 14, wherein said blunt value (TH) i is calculated by (TH).sub.i ←(TH).sub.i-1 +{TH-(TH).sub.i-1 }/C.sub.b where (TH) i-1 is a blunt value of TH calculated at a previous cycle; and C b is a coefficient determined by said maximum lean state duration and maximum rich state duration.

Claim 17

Independent Claim 156 words

An apparatus for controlling the air-fuel ratio in an internal combustion engine comprising: means for determining whether or not said engine is in a transient state; means for detecting an air-fuel ratio deviation from the optimum air-fuel ratio for each of a plurality of regions, said regions being defined by predetermined ranges of values of a second engine operating parameter, said detecting occurring only when said engine is in a transient state; and processing means, responsive to said determining means and said detecting means for performing the functions of: (a) calculating a base fuel amount in accordance with first predetermined engine operating parameters, (b) calculating a transient fuel correction amount in accordance with said detected air-fuel ratio deviation for each region as defined by said second engine operating parameter, and (c) calculating a fuel amount to be supplied to said engine by correcting said base fuel amount in accordance with said calculated transient fuel correction amount.

Claim 18

Independent Claim 156 words

An apparatus for controlling the air-fuel ratio in an internal combustion engine comprising: means for determining whether or not said engine is in a transient state; means for detecting an air-fuel ratio deviation from the optimum air-fuel ratio for each of a plurality of regions, said regions being defined by predetermined ranges of values of a second engine operating parameter, said detecting occurring only when said engine is in a transient state; and processing means, responsive to said determining means and said detecting means for performing the functions of: (a) calculating a base fuel amount in accordance with first predetermined engine operating parameters, (b) calculating a transient fuel correction amount in accordance with said detected air-fuel ratio deviation for each region as defined by said second engine operating parameter, and (c) calculating a fuel amount to be supplied to said engine by correcting said base fuel amount in accordance with said calculated transient fuel correction amount.

Claim 19

Dependent Claim 31 words

An apparatus as set forth in claim 16, wherein said processing means calculates said base fuel amount in accordance with the intake air amount and the rotational speed of said engine.

Claim 20

Dependent Claim 31 words

An apparatus as set forth in claim 16, wherein said processing means calculates said base fuel amount in accordance with the intake air pressure and the rotational speed of said engine.

Claim 21

Dependent Claim 103 words

An apparatus as set forth in claim 16, wherein: said transient state determining means comprises means for determining engine coolant temperature; and said processing means is also for: (d) determining whether or not the engine coolant temperature is lower than a predetermined value, (e) determining whether or not a predetermined time period has passed since the initiation of acceleration, (f) determining whether or not the rotational speed of said engine is within a predetermined range, and (g) determining whether or not an air-fuel ratio feedback control operation is carried out, whereby said transient state is established only when all said determinations are affirmative.

Claim 22

Dependent Claim 74 words

An apparatus as set forth in claim 16, wherein: said air-fuel ratio deviation detecting means comprises means for monitoring exhaust gases to determine when the engine is operating in lean and rich states; and said processing means is also for: (d) calculating a lean state duration for each region determined by said second predetermined engine operating parameter and (e) calculating a rich state duration for each region determined by said second predetermined engine parameter.

Claim 23

Dependent Claim 29 words

An apparatus as set forth in claim 16, wherein said detecting means includes means for detecting engine coolant temperature, said second engine operating parameter being the engine coolant temperature.

Claim 24

Dependent Claim 35 words

An apparatus as set forth in claim 16, wherein said detecting means includes means for detecting intake air amount of the engine, said second engine operating parameter being the intake air amount of said engine.

Claim 25

Dependent Claim 33 words

An apparatus as set forth in claim 16, wherein said detecting means includes means for detecting throttle opening of said engine, said second engine operating parameter being the throttle opening of said engine.

Claim 26

Dependent Claim 34 words

An apparatus as set forth in claim 16, wherein said detecting means includes means for detecting the rotational speed of said engine, said second engine operating parameter being the rotational speed of said engine.

Claim 27

Dependent Claim 82 words

An apparatus as set forth in claim 20, wherein said processing means, when performing said function (b), calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{Q/N-(Q/N).sub.i }×C.sub.a ×K where Q is the intake air amount of said engine; N is the rotational speed of said engine; (Q/N) i is a blunt value of Q/N; C a is a coefficient determined by said lean state duration and rich state duration; and K is a coefficient determined by the coolant temperature of said engine.

Claim 28

Dependent Claim 54 words

An apparatus as set forth in claim 25, wherein said processing means also calculates said blunt value (Q/N) i by (Q/N).sub.i ←(Q/N).sub.i-1 +{Q/N-(Q/N).sub.i-1 }/C.sub.b where (Q/N) i-1 is a blunt value of Q/N calculated at a previous cycle; and C b is a coefficient determined by said lean state duration and rich state duration.

Claim 29

Dependent Claim 80 words

An apparatus as set forth in claim 20, wherein said processing means, when performing said function (b), calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{PM-(PM).sub.i }×C.sub.a ×K where PM is the intake air pressure of said engine; N is the rotational speed of said engine; (PM) i is a blunt value of PM; C a is a coefficient determined by said lean state duration and rich state duration; and K is a coefficient determined by the engine coolant temperature.

Claim 30

Dependent Claim 54 words

An apparatus as set forth in claim 27, wherein said processing means also calculates said blunt value (PM) i by (PM).sub.i ←(PM).sub.i-1 +{PM-(PM).sub.i-1 }/C.sub.b where (PM) i-1 is a blunt value of PM calculated at a previous cycle; and C b is a coefficient determined by said lean state duration and rich state duration.

Claim 31

Dependent Claim 82 words

An apparatus as set forth in claim 20, wherein said processing means, when performing said function (b), calculates the transient fuel correction ratio 1+f(AEW) by 1+f(AEW)←1+{TH-(TH).sub.i }×C.sub.a ×K where TH is the intake air amount of said engine; N is the rotational speed of said engine; (TH) i is a blunt value of TH; C a is a coefficient determined by said maximum lean state duration and maximum rich state duration; and K is a coefficient determined by the engine coolant temperature.

Claim 32

Dependent Claim 53 words

An apparatus as set forth in claim 29, wherein said processing means calculates said blunt value (TH) i by (TH).sub.i ←(TH).sub.i-1 +{TH-(TH).sub.i-1 }/C.sub.b where (TH) i-1 is a blunt value of TH calculated at a previous cycle; and C b is a coefficient determined by said lean state duration and rich state duration.

Claim 33

Dependent Claim 58 words

A method as set forth in claim 1, wherein said air-fuel ratio deviation detecting step comprises the step of detecting a rich or lean state duration for each said region determined by said second predetermined engine operating parameter, thereby detecting a corresponding one of said air-fuel ratio deviations in accordance with the calculated rich or lean state determination.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-12-08	1990-06-09	1990-12-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-12-08	1994-06-09	1994-12-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-12-08	1998-06-09	1998-12-09	$7700.00	Window Closed / Lapsed

Method and apparatus for controlling air-fuel ratio in internal combustion engine

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