US4840027A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Double air-fuel ratio sensor system having improved exhaust emission characteristics
Assignee: Toyota Motor Corp
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Filing: 1987-10-08
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Granted: 1989-06-20
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Expires: 2007-10-08
Abstract
Abstract In a double air-fuel sensor system including two air-fuel ratio sensors upstream and downstream of a catalyst converter provided in an exhaust gas passage, an air-fuel ratio correction amount is calculated in accordance with the outputs of the upstream-side and downstream-side air-fuel ratio sensors, thereby obtaining an actual air-fuel ratio. When the output of the downstream-side air-fuel ratio sensor is switched from the rich side to the lean side or vice versa, the speed of renewal of the air-fuel ratio correction amount by the output of the downstream-side air-fuel ratio sensor is remarkably increased, and thereafter, this renewal speed is gradually decreased.
Inventors
- 👤 Atsuo Okumura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:21
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1482; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
295 words
A method for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, said method comprising the steps of: calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; skipping a speed of changing said air-fuel ratio correction amount in accordance with the output of the downstream-side air-fuel ratio sensor by a speed skip amount immediately after the output of said downstream-side air-side ratio sensor is switched between the rich side and the lean side; gradually decreasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor ate decreasing speed after the speed of changing said air-fuel ratio correction amount is skipped; and adjusting an actual air-fuel ratio is accordance with said air-fuel ratio correction amount; wherein said air-fuel ratio correction amount calculating step comprises the steps of: calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; and calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter; said skipping step skipping a speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor is switched between the rich side and the lean side; said gradually decreasing step gradually decreasing the speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates a lean state or a rich state.
Claim 2
Independent Claim
295 words
A method for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, said method comprising the steps of: calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; skipping a speed of changing said air-fuel ratio correction amount in accordance with the output of the downstream-side air-fuel ratio sensor by a speed skip amount immediately after the output of said downstream-side air-side ratio sensor is switched between the rich side and the lean side; gradually decreasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor ate decreasing speed after the speed of changing said air-fuel ratio correction amount is skipped; and adjusting an actual air-fuel ratio is accordance with said air-fuel ratio correction amount; wherein said air-fuel ratio correction amount calculating step comprises the steps of: calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; and calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter; said skipping step skipping a speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor is switched between the rich side and the lean side; said gradually decreasing step gradually decreasing the speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates a lean state or a rich state.
Claim 3
Dependent Claim
86 words
A method as set forth in claim 1, wherein the speed skip amount of said speed of changing of said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side is different from the speed skip amount of said speed of changing of said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side.
Claim 4
Dependent Claim
84 words
A method as set forth in claim 2, wherein the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side is larger than the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side.
Claim 5
Dependent Claim
69 words
A method as set forth in claim 1, wherein the decreasing speed of the speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a lean state is different from the decreasing speed of the speed of changing said air-fuel correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a rich state.
Claim 6
Dependent Claim
69 words
A method as set forth in claim 4, wherein the decreasing-speed of the speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a lean state is higher than the decreasing speed of the speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a rich state.
Claim 7
Dependent Claim
29 words
A method as set forth in claim 1, wherein said gradually decreasing step decreases the speed of changing said air-fuel ratio correctionamount by a predetermined ratio per unit time.
Claim 8
Dependent Claim
29 words
A method as set forth claim 1, wherein said gradually decreasing step decreases the speed of changing said air-fuel ratio correction amount by a predetermined amount per unit time.
Claim 9
Dependent Claim
85 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said air-fuel ratio correction amount is skipped down when the output of said upstream-side air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said air-fuel ratio correction amount is skipped up when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 10
Dependent Claim
74 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said air-fuel ratio correction amount is gradually decreased when the output of said upstream-side air-fuel ratio sensor is on the rich side and a rich integration amount by which said air-fuel ratio correctionamount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 11
Dependent Claim
67 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the lean side.
Claim 12
Dependent Claim
48 words
A method as set forth in claim 1, wherein said air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream-side air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on rich side or on the lean side.
Claim 13
Independent Claim
302 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, said apparatus comprising: means for calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; means for skipping a speed of changing said air-fuel ratio correction amount in accordance with the output of the downsteam-side air-fuel ratio sensor by a speed skip amount immediately after the output of said downsteam-side air-fuel ratio sensor is switched between the rich side and the lean side; means for gradually decreasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor at a decreasing speed after the speed of changing said air-fuel ratio correction amount is skipped; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; wherein said air-fuel ratio correction amount calculating means comprises: means for calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; and means for calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter; said skipping means skipping a speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor is switched between the rich side and the lean side; said gradually decreasing means gradually decreasing the speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates a lean state or a rich state.
Claim 14
Independent Claim
302 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, said apparatus comprising: means for calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; means for skipping a speed of changing said air-fuel ratio correction amount in accordance with the output of the downsteam-side air-fuel ratio sensor by a speed skip amount immediately after the output of said downsteam-side air-fuel ratio sensor is switched between the rich side and the lean side; means for gradually decreasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor at a decreasing speed after the speed of changing said air-fuel ratio correction amount is skipped; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; wherein said air-fuel ratio correction amount calculating means comprises: means for calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; and means for calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter; said skipping means skipping a speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor is switched between the rich side and the lean side; said gradually decreasing means gradually decreasing the speed of changing said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates a lean state or a rich state.
Claim 15
Dependent Claim
84 words
An apparatus as set forth in claim 12, wherein the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side is different from the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side.
Claim 16
Dependent Claim
84 words
An apparatus as set forth in claim 13, wherein the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side is larger than the speed skip amount of said speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side.
Claim 17
Dependent Claim
69 words
An apparatus as set forth in claim 12, wherein the decreasing speed of the speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a lean state is different from the decreasing speed of the speed of changing said air-fuel ratio correctionamount in the case where the output of said downstream-side air-fuel ratio sensor indicates a rich state.
Claim 18
Dependent Claim
69 words
An apparatus as set forth in claim 15, wherein the decreasing speed of the speed of changing said air-fuel ratio correction amount in the case where the output of said downstream-side air-fuel ratio sensor indicates a lean state is higher than the decreasing speed of the speed of changing said air-fuel ratio coreectionamount in the case where the output of said downstream-side air-fuel ratio sensor indicates a rich state.
Claim 19
Dependent Claim
30 words
An apparatus as set forth in claim 12, wherein said gradually decreasing means decreases the speed of changing said air-fuel ratio correction amount by a predetermined ratio per unit time.
Claim 20
Dependent Claim
30 words
An apparatus as set forth in claim 12, wherein said gradually decreasing means decreases the speed of changing said air-fuel ratio correction amount by a predetermined amount per unit time.
Claim 21
Dependent Claim
85 words
An apparatus as set forth in claim 12, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said air-fuel ratio correction amount is skipped down when the output of said upstream-side air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said air-fuel ratio correction amount is skipped up when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 22
Dependent Claim
74 words
A method as set forth in claim 12, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said air-fuel ratio correction amount is gradually decreased when the output of said upstream-side air-fuel ratio sensor is on the rich side and a rich integration amount by which said air-fuel ratio corectionamount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 23
Dependent Claim
67 words
A method as set forth in claim 12, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the lean side.
Claim 24
Dependent Claim
49 words
A method as set forth in claim 12, wherein said air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream-side air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
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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) | 1992-06-19 | 1992-12-19 | 1993-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-19 | 1996-12-19 | 1997-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-19 | 2000-12-19 | 2001-06-20 | $7700.00 | Window Closed / Lapsed |