US5070692A — Air-fuel ratio feedback control system having sin…

Claim 1

Independent Claim 249 words

A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in a warming-up mode or an after-warming-up mode; gradually changing a warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; gradually changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; calculating a coarse-adjusting term at an integration speed in accordance with the output of said air-fuel ratio sensor, when said engine is in the after-warming-up mode; calculating an after-warming-up O 2 storage term corresponding to an O 2 storage amount of said three-way catalyst converter, when said engine is in the after-warming-up mode; adjusting an actual air-fuel ratio in accordance with said warming-up O 2 storage term, when said engine is in the warming-up mode; and adjusting the actual air-fuel ratio in accordance with said coarse-adjusting term and said after-warming-up O 2 storage term, when said engine is in the after-warming-up mode;

Claim 2

Independent Claim 249 words

A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in a warming-up mode or an after-warming-up mode; gradually changing a warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; gradually changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; calculating a coarse-adjusting term at an integration speed in accordance with the output of said air-fuel ratio sensor, when said engine is in the after-warming-up mode; calculating an after-warming-up O 2 storage term corresponding to an O 2 storage amount of said three-way catalyst converter, when said engine is in the after-warming-up mode; adjusting an actual air-fuel ratio in accordance with said warming-up O 2 storage term, when said engine is in the warming-up mode; and adjusting the actual air-fuel ratio in accordance with said coarse-adjusting term and said after-warming-up O 2 storage term, when said engine is in the after-warming-up mode;

Claim 3

Dependent Claim 90 words

A method as set forth in claim 1, further comprising the steps of: greatly changing said warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is switched from the rich side to the lean side and said engine is in the warming-up mode; and greatly changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is switched from the lean side to the rich side and said engine is in the warming-up mode.

Claim 4

Dependent Claim 60 words

A method as set forth in claim 1, wherein said after-warming-up O 2 storage term calculating step makes said after-warming-up O 2 storage term large when the O 2 storage amount of said three-way catalyst converter is large and makes said after-warming-up O 2 storage term small when the O 2 storage amount of said three-way catalyst converter is small.

Claim 5

Dependent Claim 114 words

A method as set forth in claim 1, wherein said after-warming-up O 2 storage term calculating step comprises the steps of: determining whether said engine is in a lean air-fuel ratio region, in a stoichiometric air fuel ratio region, or in a rich air-fuel ratio region, by the output of said air-fuel ratio sensor; setting a positive value in said after-warming-up O 2 storage term when the engine is in said lean air-fuel ratio region; setting a negative value in said after-warming-up O 2 storage term when the engine is in said rich air-fuel ratio region; and resetting said after-warming-up O 2 storage term when the engine is in said stoichiometric air-fuel ratio region.

Claim 6

Dependent Claim 59 words

A method as set forth in claim 4, wherein said after-warming-up O 2 storage term calculating step further comprises the steps of: gradually increasing said after-warming-up O 2 storage term when the engine is in said lean air-fuel ratio region; and gradually decreasing said after-warming-up O 2 storage term when the engine is in said rich air-fuel ratio region.

Claim 7

Dependent Claim 41 words

A method as set forth in claim 1, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined time, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.

Claim 8

Dependent Claim 90 words

A method as set forth in claim 1, further comprising the steps of: greatly changing said after-warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is switched from the rich side to the lean side and said engine is in the after-warming-up mode; and greatly changing said after-warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is switched from the lean side to the rich side and said engine is in the after-warming-up mode.

Claim 9

Dependent Claim 62 words

A method as set forth in claim 1, further comprising the steps of: determining whether or not a repetition period of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the after-warming-up mode; and prohibiting the calculation of said coarse-adjusting term when the repetition period of said air-fuel ratio sensor is smaller than the redetermined period.

Claim 10

Dependent Claim 38 words

A method as set forth on claim 8, wherein said prohibiting step holds said coarse-adjusting term at an intermediate value between the maximum and minimum, values of said coarse-adjusting term immediately before the prohibition of the calculation thereof.

Claim 11

Independent Claim 260 words

An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising means for determining whether said engine is in a warming-up mode or an after-warming-up mode; means for gradually changing a warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; means for gradually changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; means for calculating a coarse-adjusting term at an integration speed in accordance with the output of said air-fuel ratio sensor, when said engine is in the after-warming-up mode; means for calculating an after-warming-up O 2 storage term corresponding to an O 2 storage amount of said three-way catalyst converter, when said engine is in the after-warming-up mode; means for adjusting an actual air-fuel ratio in accordance with said warming-up O 2 storage term, when said engine is in the warming-up mode; and means for adjusting the actual air-fuel ratio in accordance with said coarse-adjusting term and said after-warming-up O 2 storage term, when said engine is in the after-warming-up mode;

Claim 12

Independent Claim 260 words

An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising means for determining whether said engine is in a warming-up mode or an after-warming-up mode; means for gradually changing a warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; means for gradually changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio, and said engine is in the warming-up mode; means for calculating a coarse-adjusting term at an integration speed in accordance with the output of said air-fuel ratio sensor, when said engine is in the after-warming-up mode; means for calculating an after-warming-up O 2 storage term corresponding to an O 2 storage amount of said three-way catalyst converter, when said engine is in the after-warming-up mode; means for adjusting an actual air-fuel ratio in accordance with said warming-up O 2 storage term, when said engine is in the warming-up mode; and means for adjusting the actual air-fuel ratio in accordance with said coarse-adjusting term and said after-warming-up O 2 storage term, when said engine is in the after-warming-up mode;

Claim 13

Dependent Claim 91 words

An apparatus as set forth in claim 10, further comprising: means for greatly changing said warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is switched from the rich side to the lean side and said engine is in the warming-up mode; and; means for greatly changing said warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is switched from the lean side to the rich side and said engine is in the warming-up mode.

Claim 14

Dependent Claim 60 words

An apparatus as set forth in claim 10, wherein said after-warming-up O 2 storage term calculating means makes said after-warming-up O 2 storage term large when the O 2 storage amount of said three-way catalyst converter is large and makes said after-warming-up O 2 storage term small when the O 2 storage amount of said three-way catalyst converter is small.

Claim 15

Dependent Claim 122 words

An apparatus as set forth in claim 10, wherein said after-warming-up O 2 storage term calculating means comprises the steps of: means for determining whether said engine is in a lean air-fuel ratio region, in a stoichiometric air fuel ratio region, or in a rich air-fuel ratio region, by the output of said air-fuel ratio sensor; means for setting a positive value in said after-warming-up O 2 storage term when the engine is in said lean air-fuel ratio region; means for setting a negative value in said after-warming-up O 2 storage term when the engine is in said rich air-fuel ratio region; and means for resetting said after-warming-up O 2 storage term when the engine is in said stoichiometric air-fuel ratio region.

Claim 16

Dependent Claim 60 words

An apparatus as set forth in claim 13, wherein said after-warming-up O 2 storage term calculating means further comprises; means for gradually increasing said after-warming-up O 2 storage term when the engine is in said lean air-fuel ratio region; and means for gradually decreasing said after-warming-up O 2 storage term when the engine is in said rich air-fuel ratio region.

Claim 17

Dependent Claim 40 words

An apparatus as set forth in claim 10, further comprising mans for generating a self-oscillating term having a predetermined amplitude and a predetermined time, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.

Claim 18

Dependent Claim 93 words

An apparatus as set forth in claim 10, further comprising: means for greatly changing said after warming-up O 2 storage term to the rich side when the output of said air-fuel ratio sensor is switched from the rich side to the lean side and said engine is in the after warming-up mode; and means for greatly changing said after-warming-up O 2 storage term to the lean side when the output of said air-fuel ratio sensor is switched from the lean side to the rich side and said engine is in the after-warming-up mode.

Claim 19

Dependent Claim 63 words

An apparatus as set forth in claim 10, further comprising: means for determining whether or not a repetition period of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the after-warming-up mode; and means for prohibiting the calculation of said coarse-adjusting term when the repetition period of said air-fuel ratio sensor is smaller than the redetermined period.

Claim 20

Dependent Claim 38 words

An apparatus as set forth on claim 17, wherein said prohibiting means holds said coarse-adjusting term at an intermediate value between the maximum and minimum values of said coarse-adjusting term immediately before the prohibition of the calculation thereof.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-12-09	1995-06-10	1995-12-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-12-09	1999-06-10	1999-12-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-12-09	2003-06-10	2003-12-10	$7700.00	Window Closed / Lapsed

Air-fuel ratio feedback control system having single air-fuel ratio sensor downstream of or within three-way catalyst converter

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