US5052177A
Expired / Lapsed
US
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Air-fuel ratio feedback control system having single air-fuel ratio sensor downstream of or within three-way catalyst converter
Assignee: Toyota Motor Corp
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Filing: 1990-02-21
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Granted: 1991-10-01
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Expires: 2010-02-21
Abstract
Abstract In an air-fuel ratio feedback system including a single air-fuel ratio sensor downstream of or within a three-way catalyst converter, a coarse-adjusting term is calculated integrally in accordance with the output of the air-fuel ratio sensor, and a fine-adjusting term is calculated differentially at every reversion of the actual air-fuel ratio in accordance with the coarse-adjusting term and the fine-adjusting term. When a time of the reversion of the output of the air-fuel ratio sensor is small, the calculation of the coarse-adjusting term is prohibited.
Inventors
- 👤 Mitsuhiro Nada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:53
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/22; F01N3/222; F01N9/00; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1473; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D41/2458; F01N2390/00; F01N2390/02; F01N2900/00; F01N2900/04; F01N2900/0422; F02D41/2441; F02D41/2448; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12; Y02T10/40
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
236 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: gradually increasing a coarse-adjusting term when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio; gradually decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio; determining whether the output of said air-fuel ratio sensor is switched from the rich side to the lean side or vice versa; remarkably increasing a fine-adjusting term when the output of said air-fuel ratio senor is switched from the rich side to the lean side; remarkably decreasing said fine-adjusting term when the output of said air-fuel ratio sensor is switched from the lean side to the rich side; determining whether or not a time of reversions of the output of said air-fuel ratio sensor is smaller than a predetermined time; prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said time of reversions is smaller than said predetermined time; and adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said fine-adjusting term.
Claim 2
Independent Claim
236 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: gradually increasing a coarse-adjusting term when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio; gradually decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio; determining whether the output of said air-fuel ratio sensor is switched from the rich side to the lean side or vice versa; remarkably increasing a fine-adjusting term when the output of said air-fuel ratio senor is switched from the rich side to the lean side; remarkably decreasing said fine-adjusting term when the output of said air-fuel ratio sensor is switched from the lean side to the rich side; determining whether or not a time of reversions of the output of said air-fuel ratio sensor is smaller than a predetermined time; prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said time of reversions is smaller than said predetermined time; and adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said fine-adjusting term.
Claim 3
Dependent Claim
59 words
A method as set forth in claim 1, further comprising the steps of: remarkably increasing said coarse-adjusting term when the output of said air-fuel ratio sensor is switched from the rich side to the lean side; and remarkably decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is switched from lean side to the rich side.
Claim 4
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 period, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 5
Dependent Claim
57 words
A method as set forth in claim 3, further comprising the steps of: determining whether or not said engine is in an idling state; decreasing said predetermined amplitude of said self-oscillating term when said engine is in said idling state; and increasing said predetermined period of said self-oscillating term when said engine is in said idling state.
Claim 6
Dependent Claim
48 words
A method as set forth in claim 1, further comprising the steps of: determining whether or not said engine is in a warming-up state; and prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said engine is in said warming-up state.
Claim 7
Dependent Claim
40 words
A method as set forth in claim 3, further comprising the steps of: determining whether of not said engine is in a warming-up state; and decreasing said amplitude of said self-oscillating term when said engine is in said warming-up state.
Claim 8
Dependent Claim
49 words
A method as set forth in claim 1, further comprising a step of calculating an O 2 storage term corresponding to an O 2 storage amount in said three-way catalyst converter, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said O 2 storage term.
Claim 9
Dependent Claim
33 words
A method as set forth in claim 7, wherein said O 2 storage term calculating step calculates said O 2 storage term in accordance with a change of a load of said engine.
Claim 10
Dependent Claim
32 words
A method as set forth in claim 7, wherein said O 2 storage term calculating step calculates said O 2 storage term in accordance with the output of said air-fuel ratio sensor.
Claim 11
Dependent Claim
61 words
A method as set forth in claim 9, wherein said O 2 storage term calculating step increases said O 2 storage term when the output of said air-fuel ratio sensor continues a lean state for a predetermined period, and decreases said O 2 storage term when the output of said air-fuel ratio sensor continues a rich state for said predetermined period.
Claim 12
Independent Claim
249 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 gradually increasing a coarse-adjusting term when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio; means for gradually decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio; means for determining whether the output of said air-fuel ratio sensor is switched from the rich side to the lean side or vice versa; means for remarkably increasing a fine-adjusting term when the output of said air-fuel ratio sensor is switched from the rich side to the lean side; means for remarkably decreasing said fine-adjusting term when the output of said air-fuel ratio sensor is switched from the lean side to the rich side; means for determining whether or not a time of reversions of the output of said air-fuel ratio sensor is smaller than a predetermined time; means for prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said time of reversions is smaller than said predetermined time; and means for adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said fine-adjusting term.
Claim 13
Independent Claim
249 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 gradually increasing a coarse-adjusting term when the output of said air-fuel ratio sensor is on the lean side with respect to the stoichiometric air-fuel ratio; means for gradually decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is on the rich side with respect to the stoichiometric air-fuel ratio; means for determining whether the output of said air-fuel ratio sensor is switched from the rich side to the lean side or vice versa; means for remarkably increasing a fine-adjusting term when the output of said air-fuel ratio sensor is switched from the rich side to the lean side; means for remarkably decreasing said fine-adjusting term when the output of said air-fuel ratio sensor is switched from the lean side to the rich side; means for determining whether or not a time of reversions of the output of said air-fuel ratio sensor is smaller than a predetermined time; means for prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said time of reversions is smaller than said predetermined time; and means for adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said fine-adjusting term.
Claim 14
Dependent Claim
60 words
An apparatus as set forth in claim 11, further comprising: means for remarkably increasing said coarse-adjusting term when the output of said air-fuel ratio sensor is switched from the rich side to the lean side; and means for remarkably decreasing said coarse-adjusting term when the output of said air-fuel ratio sensor is switched from lean side to the rich side.
Claim 15
Dependent Claim
40 words
An apparatus as set forth in claim 11, further comprising: means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 16
Dependent Claim
60 words
An apparatus as set forth in claim 13, further comprising: means for determining whether or not said engine is in an idling state; means for decreasing said predetermined amplitude of said self-oscillating term when said engine is in said idling state; and means for increasing said predetermined period of said self-oscillating term when said engine is in said idling state.
Claim 17
Dependent Claim
49 words
An apparatus as set forth in claim 11, further comprising: means for determining whether or not said engine is in a warming-up state; and means for prohibiting the calculation of said coarse-adjusting term by the output of said air-fuel ratio sensor when said engine is in said warming-up state.
Claim 18
Dependent Claim
41 words
An apparatus as set forth in claim 13, further comprising: means for determining whether or not said engine is in a warming-up state; and means for decreasing said amplitude of said self-oscillating term when said engine is in said warming-up state.
Claim 19
Dependent Claim
48 words
An apparatus as set forth in claim 11, further comprising: means for calculating an O 2 storage term corresponding to an O 2 storage amount in said three-way catalyst converter, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said O 2 storage term.
Claim 20
Dependent Claim
33 words
An apparatus as set forth in claim 17, wherein said O 2 storage term calculating means calculates said O 2 storage term in accordance with a change of a load of said engine.
Claim 21
Dependent Claim
32 words
An apparatus as set forth in claim 17, wherein said O 2 storage term calculating means calculates said O 2 storage term in accordance with the output of said air-fuel ratio sensor.
Claim 22
Dependent Claim
61 words
An apparatus as set forth in claim 19, wherein said O 2 storage term calculating means increases said O 2 storage term when the output of said air-fuel ratio sensor continues a lean state for a predetermined period, and decreases said O 2 storage term when the output of said air-fuel ratio sensor continues a rich state for said predetermined period.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-30 | 1995-04-01 | 1995-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-30 | 1999-04-01 | 1999-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-30 | 2003-04-01 | 2003-10-01 | $7700.00 | Window Closed / Lapsed |