Patent US5619852A successfully refreshed from Google Patents.
US5619852A
Expired / Lapsed
US
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Air/fuel ratio control system for internal combustion engine
Assignee: Hitachi Unisia Automotive Ltd
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Filing: 1995-07-07
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Granted: 1997-04-15
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Expires: 2015-07-07
Abstract
Abstract In an air/fuel ratio control system for an internal combustion engine, having a second air/fuel ratio sensor disposed downstream of a catalytic converter, a computing type used for computing a second air/fuel ratio correction quantity in accordance with an output of the second air/fuel ratio sensor is switched in such a manner that the second air/fuel ratio quantity is set larger when the output of the second air/fuel ratio sensor is outside a reference level range than when the output of the second air/fuel ratio sensor is within the reference level range.
Inventors
- 👤 Akira Uchikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:26
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/1444; F02D41/1454; F02D41/1456
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
301 words
An air/fuel ratio control system for an internal combustion engine having an exhaust passage and a catalytic converter provided to the exhaust passage, comprising: first air/fuel ratio detecting means provided to the exhaust passage at a location upstream of the catalytic converter for producing a variable output in accordance with a density of a particular exhaust gas component which is variable with variation of an air/fuel ratio; second air/fuel ratio detecting means provided to the exhaust passage at a location downstream of the catalytic converter for producing a variable output in accordance with a density of a particular exhaust gas component which is variable with variation of an air/fuel ratio; first air/fuel ratio correction quantity computing means for computing a first air/fuel ratio correction quantity in accordance with the output of said first air/fuel ratio detecting means; second air/fuel ratio correction quantity computing means for computing a second air/fuel ratio correction quantity for correcting said first air/fuel ratio correction quantity in accordance with the output of said second air/fuel ratio detecting means; final air/fuel ratio correction quantity computing means for computing a final air/fuel ratio correction quantity based on said first air/fuel ratio correction quantity and said second air/fuel ratio correction quantity; air/fuel ratio control quantity setting means for correcting and setting an air/fuel ratio control quantity based on the final air/fuel ratio correction quantity computed by said final air/fuel ratio correction quantity computing means; and computing type switching means for switching a computing type of said second air/fuel ratio correction quantity computing means in such a manner that said second air/fuel ratio correction quantity is set larger when the output of said second air/fuel ratio detecting means is outside a reference level range than when the output of said second air/fuel ratio detecting means is within the reference level range.
Claim 2
Dependent Claim
301 words
An air/fuel ratio control system for an internal combustion engine having an exhaust passage and a catalytic converter provided to the exhaust passage, comprising: first air/fuel ratio detecting means provided to the exhaust passage at a location upstream of the catalytic converter for producing a variable output in accordance with a density of a particular exhaust gas component which is variable with variation of an air/fuel ratio; second air/fuel ratio detecting means provided to the exhaust passage at a location downstream of the catalytic converter for producing a variable output in accordance with a density of a particular exhaust gas component which is variable with variation of an air/fuel ratio; first air/fuel ratio correction quantity computing means for computing a first air/fuel ratio correction quantity in accordance with the output of said first air/fuel ratio detecting means; second air/fuel ratio correction quantity computing means for computing a second air/fuel ratio correction quantity for correcting said first air/fuel ratio correction quantity in accordance with the output of said second air/fuel ratio detecting means; final air/fuel ratio correction quantity computing means for computing a final air/fuel ratio correction quantity based on said first air/fuel ratio correction quantity and said second air/fuel ratio correction quantity; air/fuel ratio control quantity setting means for correcting and setting an air/fuel ratio control quantity based on the final air/fuel ratio correction quantity computed by said final air/fuel ratio correction quantity computing means; and computing type switching means for switching a computing type of said second air/fuel ratio correction quantity computing means in such a manner that said second air/fuel ratio correction quantity is set larger when the output of said second air/fuel ratio detecting means is outside a reference level range than when the output of said second air/fuel ratio detecting means is within the reference level range.
Claim 3
Dependent Claim
39 words
An air/fuel ratio control system according to claim 1, further comprising means for variably setting an air/fuel ratio rich side limit value of said reference level range in accordance with a temperature of said second air/fuel ratio detecting means.
Claim 4
Dependent Claim
63 words
An air/fuel ratio control system according to claim 1, wherein said computing type switching means computes said second air/fuel ratio correction quantity by integral control when the output of said second air/fuel ratio detecting means is within said reference level range and by proportional plus integral control when the output of said second air/fuel ratio detecting means is outside said reference level range.
Claim 5
Dependent Claim
65 words
An air/fuel ratio control system according to claim 1, wherein said computing type switching means switches said computing type in such a manner that a gain of control constant is made larger when the output of said second air/fuel ratio detecting means is outside said reference level range than when the output of said second air/fuel ratio detecting means is within said reference level range.
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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) | 2000-04-14 | 2000-10-14 | 2001-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-04-14 | 2004-10-14 | 2005-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-04-14 | 2008-10-14 | 2009-04-15 | $7700.00 | Window Closed / Lapsed |