Patent US4809501A successfully refreshed from Google Patents.
US4809501A
Expired / Lapsed
US
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Double air-fuel ratio sensor system having improved exhaust emission characteristics
Assignee: Toyota Motor Corp
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Filing: 1988-01-15
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Granted: 1989-03-07
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Expires: 2008-01-15
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 results of the comparison of the outputs of the upstream-side and downstream-side air-fuel ratio sensors with first and second reference voltages, respectively, thereby obtaining an actual air-fuel ratio. The second reference voltage is changed in accordance with the load of the engine, to change the mean air-fuel ratio.
Inventors
- 👤 Nobuaki Kayanuma
- 👤 Toshinari Nagai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:43
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1479; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
145 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, comprising the steps of: comparing the output of said upstream-side air-fuel ratio sensor with a first reference voltage; detecting a load of said engine; calculating a second reference voltage in accordance with said load of said engine; comparing the output of said downstreamside air-fuel ratio sensor with said second reference voltage; calculating an air-fuel ratio correction amount in accordance with the results of the comparison of the outputs of said upstream-side and downstream-side air-fuel ratio sensors; and adjusting an actual air-fuel ratio of said engine in accordance with said air-fuel ratio correction amount.
Claim 2
Independent Claim
145 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, comprising the steps of: comparing the output of said upstream-side air-fuel ratio sensor with a first reference voltage; detecting a load of said engine; calculating a second reference voltage in accordance with said load of said engine; comparing the output of said downstreamside air-fuel ratio sensor with said second reference voltage; calculating an air-fuel ratio correction amount in accordance with the results of the comparison of the outputs of said upstream-side and downstream-side air-fuel ratio sensors; and adjusting an actual air-fuel ratio of said engine in accordance with said air-fuel ratio correction amount.
Claim 3
Dependent Claim
54 words
A method as set forth in claim 1, wherein said second reference voltage calculating step comprises the steps of: placing said second reference voltage on the rich side when said load of said engine is large; and placing said second reference voltage on the lean side when said load of said engine is small.
Claim 4
Dependent Claim
99 words
A method as set forth in claim 1, wherein said air-fuel ratio correction amount calculating step comprises the steps of: calculating a first air-fuel ratio correction amount in accordance with the result of the comparison of the output of said upstream-side air-fuel ratio sensor; and calculating a second air-fuel ratio correction amount allocated to a load region including the current load of said engine in accordance with the result of the comparison of the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 5
Dependent Claim
81 words
A method as set forth in claim 1, wherein said air-fuel ratio correction amount calculating step comprises a step of calculating an air-fuel ratio feedback control parameter allocated to a load region including the current load of said engine in accordance with the result of the comparison of the output of said downstream-side air-fuel ratio sensor, thereby 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.
Claim 6
Dependent Claim
85 words
A method as set forth in claim 4, 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 7
Dependent Claim
75 words
A method as set forth in claim 4, 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 correction amount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 8
Dependent Claim
67 words
A method as set forth in claim 4, 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 9
Dependent Claim
49 words
A method as set forth in claim 4, 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.
Claim 10
Dependent Claim
55 words
A method as set forth in claim 1, further comprising the steps of: determining whether or not a change of said load of said engine is larger than a definite value; and prohibiting the calculation of said second reference voltage when the change of said load of said engine is larger than said definite value.
Claim 11
Independent Claim
155 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, comprising: means for comparing the output of said upstream-side air-fuel ratio sensor with a first reference voltage; means for detecting a load of said engine; means for calculating a second reference voltage in accordance with said load of said engine; means for comparing the output of said downstream-side air-fuel ratio sensor with said second reference voltage; and means for calculating an air-fuel ratio correction amount in accordance with the results of a comparison of the outputs of said upstream-side and downstream-side air-fuel ratio sensors; and means for adjusting an actual air-fuel ratio of said engine in accordance with said air-fuel ratio correction amount.
Claim 12
Independent Claim
155 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, comprising: means for comparing the output of said upstream-side air-fuel ratio sensor with a first reference voltage; means for detecting a load of said engine; means for calculating a second reference voltage in accordance with said load of said engine; means for comparing the output of said downstream-side air-fuel ratio sensor with said second reference voltage; and means for calculating an air-fuel ratio correction amount in accordance with the results of a comparison of the outputs of said upstream-side and downstream-side air-fuel ratio sensors; and means for adjusting an actual air-fuel ratio of said engine in accordance with said air-fuel ratio correction amount.
Claim 13
Dependent Claim
55 words
An apparatus as set forth in claim 10, wherein said second reference voltage calculating means comprises: means for placing said second reference voltage on the rich side when said load of said engine is large; and means for placing said second reference voltage on the lean side when said load of said engine is small.
Claim 14
Dependent Claim
100 words
An apparatus as set forth in claim 10, wherein said air-fuel ratio correction amount calculating means comprises: means for calculating a first air-fuel ratio correction amount in accordance with the result of the comparison of the output of said upstream-side air-fuel ratio sensor; and means for calculating a second air-fuel ratio correction amount allocated to a load region including the current load of said engine in accordance with the result of the comparison of the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 15
Dependent Claim
80 words
An apparatus as set forth in claim 10, wherein said air-fuel ratio correction amount calculating means comprises means for calculating an air-fuel ratio feedback control parameter allocated to a load region including the current load of said engine in accordance with the result of the comparison of the output of said downstream-side air-fuel ratio sensor, thereby 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.
Claim 16
Dependent Claim
85 words
An apparatus as set forth in claim 13, 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 17
Dependent Claim
75 words
An apparatus as set forth in claim 13, 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 correction amount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 18
Dependent Claim
67 words
An apparatus as set forth in claim 13, 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 19
Dependent Claim
49 words
An apparatus as set forth in claim 13, 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.
Claim 20
Dependent Claim
56 words
An apparatus as set forth in claim 10, further comprising: means for determining whether or not a change of said load of said engine is larger than a definite value; and means for prohibiting the calculation of said second reference voltage when the change of said load of said engine is larger than said definite value.
Claim 21
Dependent Claim
36 words
An apparatus as set forth in claim 10, further comprising means for simultaneously heating said upstream-side and downstream-side air-fuel ratio sensors in accordance with a coolant temperature of said engine and said load of said engine.
Claim 22
Dependent Claim
36 words
An apparatus as set forth in claim 10, further comprising means for separately heating said upstream-side and downstream-side air-fuel ratio sensors in accordance with a coolant temperature of said engine and said load of said engine.
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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) | 1992-03-06 | 1992-09-05 | 1993-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-06 | 1996-09-05 | 1997-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-06 | 2000-09-05 | 2001-03-07 | $7700.00 | Window Closed / Lapsed |