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US5491975A
Expired / Lapsed
US
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Air-fuel ratio control system for internal combustion engine
Assignee: Denso Corp
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Filing: 1993-07-02
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Granted: 1996-02-20
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Expires: 2013-07-02
Abstract
Abstract In an air-fuel ratio control system for an internal combustion engine, a target air-fuel ratio is set on a side opposite to a direction of deviation of a monitored upstream side air-fuel ratio in such a manner as to counterbalance or offset the deviation of the upstream side air-fuel ratio. The deviation of the upstream side air-fuel ratio may be derived in the form of an mount of a particular component adsorbed in a catalytic converter. A learned value may be used to correct the monitored upstream side air-fuel ratio. Further, a monitored downstream side air-fuel ratio may be used to monitor the setting of the target air-fuel ratio.
Inventors
- 👤 Yukihiro Yamashita
- 👤 Kenji Ikuta
- 👤 Shigenori Isomura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:58
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D41/2474; F02D41/2477
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
195 words
An air-fuel ratio control system for an internal combustion engine, comprising: air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter; deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios when a given condition is satisfied; target air-fuel ratio setting means, based on said sum of the deviations derived by said deviation condition determining means, for setting a target air-fuel ratio on a side opposite to a direction of said sum of the deviations in such a manner as to counterbalance said sum of the deviations, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said sum of the deviations is counterbalanced to a given extent; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
Claim 2
Dependent Claim
195 words
An air-fuel ratio control system for an internal combustion engine, comprising: air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter; deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios when a given condition is satisfied; target air-fuel ratio setting means, based on said sum of the deviations derived by said deviation condition determining means, for setting a target air-fuel ratio on a side opposite to a direction of said sum of the deviations in such a manner as to counterbalance said sum of the deviations, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said sum of the deviations is counterbalanced to a given extent; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
Claim 3
Dependent Claim
37 words
The air-fuel ratio control system as set forth in claim 1, wherein said sum of the deviations represents an amount of a particular component absorbed in said catalytic converter, said particular component included in the exhaust gas.
Claim 4
Dependent Claim
38 words
The air-fuel ratio control system as set forth in claim 2, wherein said target air-fuel ratio setting means sets said target air-fuel ratio so as to counterbalance said absorbed amount of the particular component in said catalytic converter.
Claim 5
Dependent Claim
125 words
The air-fuel ratio control system as set forth in claim 1, wherein said deviation condition determining means includes: downstream-side air-fuel ratio detecting means, provided downstream of said catalytic converter, for detecting an air-fuel ratio of the air-fuel mixture based on the exhaust gas having passed through the catalytic converter; and air-fuel ratio learning means for learning said upstream-side air-fuel ratio detected by said upstream-side air-fuel ratio detecting means as a stoichiometric air-fuel ratio when said downstream-side air-fuel ratio detected by said downstream-side air-fuel ratio detecting means is near the stoichiometric air-fuel ratio, and for correcting said upstream-side air-fuel ratio based on a result of said learning, said corrected upstream-side air-fuel ratio used by said target air-fuel ratio setting means to derive said target air-fuel ratio.
Claim 6
Dependent Claim
97 words
The air-fuel ratio control system as set forth in claim 1, wherein said target air-fuel ratio setting means includes: downstream-side air-fuel ratio detecting means, provided downstream of said catalytic converter, for detecting an air-fuel ratio of the air-fuel mixture based on the exhaust gas having passed through the catalytic converter; and setting suspension means for determining, based on said downstream-side air-fuel ratio detected by said downstream-side air-fuel ratio detecting means, whether a setting direction of the target air-fuel ratio is correct, and for suspending said setting of the target air-fuel ratio when said setting direction is wrong.
Claim 7
Dependent Claim
45 words
The air-fuel ratio control system as set forth in claim 5, wherein said setting suspension means suspends the setting of the target air-fuel ratio by comparing said detected downstream-side air-fuel ratio with a preset rich side limit value or a preset lean side limit value.
Claim 8
Dependent Claim
190 words
An air-fuel ratio control system for an internal combustion engine, comprising: air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter; deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios and for determining whether said sum of the deviations exceeds a preset rich-side limit value or a preset lean-side limit value; target air-fuel ratio setting means for setting a target air-fuel ratio to a lean-side target value which is leaner than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said rich-side limit value and to a rich-side target value which is richer than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said lean-side limit value; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel setting means.
Claim 9
Dependent Claim
190 words
An air-fuel ratio control system for an internal combustion engine, comprising: air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter; deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios and for determining whether said sum of the deviations exceeds a preset rich-side limit value or a preset lean-side limit value; target air-fuel ratio setting means for setting a target air-fuel ratio to a lean-side target value which is leaner than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said rich-side limit value and to a rich-side target value which is richer than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said lean-side limit value; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel setting means.
Claim 10
Dependent Claim
48 words
The air-fuel ratio control system as set forth in claim 7, wherein said sum of the deviations represents an amount of a particular component adsorbed in said catalytic converter, and wherein said deviation condition determining means determines whether said absorbed amount exceeds said rich or lean-side limit value.
Claim 11
Dependent Claim
175 words
An air-fuel ratio control system for an internal combustion engine, comprising: downstream-side air-fuel ratio detecting means, provided downstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas having passed through said catalytic converter; target air-fuel ratio setting means for determining a deviation direction of the detected downstream-side air-fuel ratio with respect to a stoichiometric air-fuel ratio, and for setting a target air-fuel ratio on a side opposite to said deviation direction across the stoichiometric air-fuel ratio so as to counterbalance a deviation of said detected downstream-side air-fuel ratio with respect to the stoichiometric air-fuel ratio, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said deviation of the detected downstream-side air-fuel ratio is counterbalanced to a given extent; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
Claim 12
Dependent Claim
175 words
An air-fuel ratio control system for an internal combustion engine, comprising: downstream-side air-fuel ratio detecting means, provided downstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas having passed through said catalytic converter; target air-fuel ratio setting means for determining a deviation direction of the detected downstream-side air-fuel ratio with respect to a stoichiometric air-fuel ratio, and for setting a target air-fuel ratio on a side opposite to said deviation direction across the stoichiometric air-fuel ratio so as to counterbalance a deviation of said detected downstream-side air-fuel ratio with respect to the stoichiometric air-fuel ratio, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said deviation of the detected downstream-side air-fuel ratio is counterbalanced to a given extent; and fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
Claim 13
Dependent Claim
60 words
The air-fuel ratio control system as set forth in claim 9, wherein said target air-fuel ratio setting means performs said setting when the detected downstream side air-fuel ratio is outside a range defined by a preset rich-side limit value and a preset lean-side limit value, and performs said restoration when the detected downstream side air-fuel ratio falls within said range.
Claim 14
Dependent Claim
80 words
The air-fuel ratio control system as set forth in claim 1, wherein the deviation of the detected air-fuel ratio to a rich side with respect to the stoichiometric air-fuel ratio and the deviation of the detected air-fuel ratio to a lean side with respect to the stoichiometric air-fuel ratio are assigned opposite signs so that said sum of the deviations represents an amount of a particular component adsorbed in said catalytic converter, said particular component included in the exhaust gas.
Claim 15
Dependent Claim
80 words
The air-fuel ratio control system as set forth in claim 7, wherein the deviation of the detected air-fuel ratio to a rich side with respect to the stoichiometric air-fuel ratio and the deviation of the detected air-fuel ratio to a lean side with respect to the stoichiometric air-fuel ratio are assigned opposite signs so that said sum of the deviations represents an amount of a particular component adsorbed in said catalytic converter, said particular component included in the exhaust gas.
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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) | 1999-02-19 | 1999-08-21 | 2000-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-19 | 2003-08-21 | 2004-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-19 | 2007-08-21 | 2008-02-20 | $7700.00 | Window Closed / Lapsed |