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US4627402A
Expired / Lapsed
US
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Method and apparatus for controlling air-fuel ratio in internal combustion engine
Assignee: Soken Inc
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Filing: 1985-11-13
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Granted: 1986-12-09
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Expires: 2005-11-13
Abstract
Abstract In an internal combustion engine having a plurality of cylinders, an air-fuel ratio signal is sampled and held for a selected cylinder, and an air-fuel ratio feedback amount is calculated in accordance with the sampled and held air-fuel ratio signal. During a learning control, a cylinder on the leanest side is determined by changing the selected cylinder. During a feedback control without the learning control, the selected cylinder is fixed as the cylinder on the leanest side.
Inventors
- 👤 Kimitaka Saito
- 👤 Kenzi Iwamoto
- 👤 Tsuneyuki Egami
- 👤 Tsutomu Saito
- 👤 Takesi Matuyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:24
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/008; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
140 words
A method for controlling the air-fuel ratio in an internal combustion engine having a plurality of cylinders, comprising the steps of: calculating a base fuel amount in accordance with predetermined parameters of said engine; generating an air-fuel ratio signal of said engine; selecting a cylinder from said cylinders; sampling and holding said air-fuel ratio signal corresponding to said selected cylinder; calculating an air-fuel ratio feedback amount in accordance with the sampled and held air-fuel ratio signal during a first predetermined engine state; adjusting the actual air-fuel ratio in accordance with said base fuel amount and said air-fuel ratio feedback amount; determining a cylinder on the leanest side by changing said selected cylinder during a second predetermined engine state; and setting said cylinder on the leanest side as said selected cylinder during a state other than said second predetermined engine state.
Claim 2
Independent Claim
140 words
A method for controlling the air-fuel ratio in an internal combustion engine having a plurality of cylinders, comprising the steps of: calculating a base fuel amount in accordance with predetermined parameters of said engine; generating an air-fuel ratio signal of said engine; selecting a cylinder from said cylinders; sampling and holding said air-fuel ratio signal corresponding to said selected cylinder; calculating an air-fuel ratio feedback amount in accordance with the sampled and held air-fuel ratio signal during a first predetermined engine state; adjusting the actual air-fuel ratio in accordance with said base fuel amount and said air-fuel ratio feedback amount; determining a cylinder on the leanest side by changing said selected cylinder during a second predetermined engine state; and setting said cylinder on the leanest side as said selected cylinder during a state other than said second predetermined engine state.
Claim 3
Dependent Claim
60 words
A method as set forth in claim 1, wherein said leanest cylinder determining step comprises the steps of: calculating a mean value of said air-fuel ratio feedback amount for each selected cylinder; and detecting a maximum value from the calculated mean values for said cylinders, thereby determining said cylinder on the leanest side as a cylinder having said maximum value.
Claim 4
Dependent Claim
38 words
A method as set forth in claim 2, wherein said mean value calculating step comprises a step of calculating a mean value of four sequential air-fuel ratio feedback amounts immediately before the switching of said air-fuel ratio signal.
Claim 5
Dependent Claim
51 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback amount calculating step comprises a step of comparing the value of said air-fuel ratio signal with a predetermined value corresponding to a stoichiometric air-fuel ratio, thereby calculating said air-fuel ratio feedback amount in accordance with the comparison result.
Claim 6
Dependent Claim
51 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback amount calculating step comprises a step of comparing the value of said air-fuel ratio signal with a predetermined value corresponding to a lean air-fuel ratio, thereby calculating said air-fuel ratio feedback amount in accordance with the comparison result.
Claim 7
Independent Claim
153 words
An apparatus for controlling the air-fuel ratio in an internal combustion engine having a plurality of cylinders, comprising: means for calculating a base fuel amount in accordance with predetermined parameters of said engine; means for generating an air-fuel ratio signal of said engine; means for selecting a cylinder from said cylinders; means for sampling and holding said air-fuel ratio signal corresponding to said selected cylinder; means for calculating an air-fuel ratio feedback amount in accordance with the sampled and held air-fuel ratio signal during a first predetermined engine state; means for adjusting the actual air-fuel ratio in accordance with said base fuel amount and said air-fuel ratio feedback amount; means for determining a cylinder on the leanest side by changing said selected cylinder during a second predetermined engine state; and means for setting said cylinder on the leanest side as said selected cylinder during a state other than said second predetermined engine state.
Claim 8
Independent Claim
153 words
An apparatus for controlling the air-fuel ratio in an internal combustion engine having a plurality of cylinders, comprising: means for calculating a base fuel amount in accordance with predetermined parameters of said engine; means for generating an air-fuel ratio signal of said engine; means for selecting a cylinder from said cylinders; means for sampling and holding said air-fuel ratio signal corresponding to said selected cylinder; means for calculating an air-fuel ratio feedback amount in accordance with the sampled and held air-fuel ratio signal during a first predetermined engine state; means for adjusting the actual air-fuel ratio in accordance with said base fuel amount and said air-fuel ratio feedback amount; means for determining a cylinder on the leanest side by changing said selected cylinder during a second predetermined engine state; and means for setting said cylinder on the leanest side as said selected cylinder during a state other than said second predetermined engine state.
Claim 9
Dependent Claim
61 words
An apparatus as set forth in claim 6, wherein said leanest cylinder determining means comprises: means for calculating a mean value of said air-fuel ratio feedback amount for each selected cylinder; and means for detecting a maximum value from the calculated mean valued for said cylinders, thereby determining said cylinder on the leanest side as a cylinder having said maximum value.
Claim 10
Dependent Claim
37 words
An apparatus as set forth in claim 7, wherein said mean value calculating means comprises means for calculating a mean value of four sequential air-fuel ratio feedback amounts immediately before the switching of said air-fuel ratio signal.
Claim 11
Dependent Claim
50 words
An apparatus as set forth in claim 6, wherein said air-fuel ratio feedback amount calculating means comprises means for comparing the value of said air-fuel ratio signal with a predetermined value corresponding to a stoichiometric air-fuel ratio, thereby calculating said air-fuel ratio feedback amount in accordance with the comparison result.
Claim 12
Dependent Claim
50 words
An apparatus as set forth in claim 6, wherein said air-fuel ratio feedback amount calculating means comprises means for comparing the value of said air-fuel ratio signal with a predetermined value corresponding to a lean air-fuel ratio, thereby calculating said air-fuel ratio feedback amount in accordance with the comparison result.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| 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 |