US4970858A
Expired / Lapsed
US
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Air-fuel ratio feedback system having improved activation determination for air-fuel ratio sensor
Assignee: Toyota Motor Corp
•
Filing: 1989-03-27
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Granted: 1990-11-20
•
Expires: 2009-03-27
Abstract
Abstract In an air-fuel ratio feedback control system including at least one air-fuel ratio sensor downstream of or within a catalyst converter provided in an exhaust gas passage, an actual air-fuel ratio is controlled in accordance with the output of the air-fuel ratio sensor, which is supplied to a pull-up type input circuit. After the output of the pull-up type input circuit becomes lower than an activation control level, the determination of whether or not the air-fuel ratio sensor is activated is carried out by determining whether or not the output of the pull-up type input circuit is within an active region, depending on the base air-fuel ratio of the engine.
Inventors
- 👤 Hiroki Matsuoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:11
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1473; F02D41/1475; F02D41/1476; F02D41/1477; F02D41/148
Claims Analysis
Total Claims: 50
Claim 1
Independent Claim
268 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising the steps of: determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher than a rich state level of said pull-up type input circuit after said engine is warmed-up; determining whether the air-fuel ratio of said engine is rich or lean in accordance which the output of said pull-up type input circuit; determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level and the air-fuel ratio of said engine is lean; and adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state.
Claim 2
Independent Claim
268 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising the steps of: determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher than a rich state level of said pull-up type input circuit after said engine is warmed-up; determining whether the air-fuel ratio of said engine is rich or lean in accordance which the output of said pull-up type input circuit; determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level and the air-fuel ratio of said engine is lean; and adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state.
Claim 3
Dependent Claim
124 words
A method as set forth in claim 1, wherein said air-fuel ratio determining step comprises the steps of: determining whether or not a predetermined time has elapsed after the output of said pull-up type input circuit becomes lower than said first level; determining whether or not the output of said pull-up type input circuit is higher than a third level between said first and second levels after said predetermined time has elapsed, thereby determining that the air-fuel ratio of said engine is rich when the output of said pull-up type input circuit is higher than said third level, and that the air-fuel ratio of said engine is lean when the output of said pull-up type input circuit is not higher than said third level.
Claim 4
Dependent Claim
92 words
A method as set forth in claim 1, wherein said air-fuel ratio determining step comprises a step of calculating a variation of the output of said pull-up type input circuit after the output of said pull-up type input circuit becomes lower than said first level, thereby determining that the air-fuel ratio of said engine is lean when said variation is larger than a first predetermined value, and that the air-fuel ratio of said engine is rich when said deviation is smaller than a second predetermined value smaller than said first predetermined value.
Claim 5
Dependent Claim
32 words
A method as set forth in claim 3, wherein said deviation is calculated during a predetermined interval after the output of said pull-up type input circuit becomes lower than said first level.
Claim 6
Dependent Claim
20 words
A method as set forth in claim 3, wherein said deviation is calculated during two or more successive predetermined intervals.
Claim 7
Dependent Claim
68 words
A method as set forth in claim 3, wherein said deviation calculating step comprises the step of: counting a duration when the output of said pull-up type input circuit is between said first and third levels, thereby determining that said deviation is small when said duration is larger than a first predetermined duration, and that said deviation is large when said second duration is larger than predetermined duration.
Claim 8
Dependent Claim
64 words
A method as set forth in claim 1, further comprising the steps of: determining whether or not the output of said pull-up type input circuit is higher than a fourth level higher than said first level; and determining that said downstream-side air-fuel ratio sensor is in a nonactivation state when the output of said pull-up type input circuit is higher than said fourth level.
Claim 9
Dependent Claim
71 words
A method as set forth in claim 1, wherein said pull-up type input circuit comprises: a resistor connected between an output of said downstream-side air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said downstream-side air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.
Claim 10
Dependent Claim
72 words
A method as set forth in claim 1, wherein said actual air-fuel ratio adjusting step comprises the steps of: calculating a first air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor; calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and adjusting said actual air-fuel ratio in accordance with said first and second air-fuel ratio correction amounts.
Claim 11
Dependent Claim
75 words
A method as set forth in claim 1, wherein said actual air-fuel ratio adjusting 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; calculating an 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; and adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 12
Dependent Claim
85 words
A method as set forth in claim 10, 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 13
Dependent Claim
75 words
A method as set forth in claim 10, 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 14
Dependent Claim
65 words
A method as set forth in claim 10, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time 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 for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the leans side.
Claim 15
Dependent Claim
49 words
A method as set forth in claim 10, 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 16
Independent Claim
256 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising the steps of: determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher rich state level of said pull-up type input after said engine is warmed-up; determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state.
Claim 17
Independent Claim
256 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising the steps of: determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher rich state level of said pull-up type input after said engine is warmed-up; determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state.
Claim 18
Dependent Claim
124 words
A method as set forth in claim 15, wherein said air-fuel ratio determining step comprises the steps of: determining whether or not a predetermined time has elapsed after the output of said pull-up type input circuit becomes lower than said first level; determining whether or not the output of said pull-up type input circuit is higher than a third level between said first and second levels after said predetermined time has elapsed, thereby determining that the air-fuel ratio of said engine is rich when the output of said pull-up type input circuit is higher than said third level, and that the air-fuel ratio of said engine is lean when the output of said pull-up type input circuit is not higher than said third level.
Claim 19
Dependent Claim
92 words
A method as set forth in claim 15, wherein said air-fuel ratio determining step comprises a step of calculating a variation of the output of said pull-up type input circuit after the output of said pull-up type input circuit becomes lower than said first level, thereby determining that the air-fuel ratio of said engine is lean when said variation is larger than a first predetermined value, and that the air-fuel ratio of said engine is rich when said deviation is smaller than a second predetermine value smaller than said first predetermined value.
Claim 20
Dependent Claim
32 words
A method as set forth in claim 17, wherein said deviation is calculated during a predetermined interval after the output of said pull-up type input circuit becomes lower than said first level.
Claim 21
Dependent Claim
20 words
A method as set forth in claim 17, wherein said deviation is calculated during two or more successive predetermined intervals.
Claim 22
Dependent Claim
69 words
A method as set forth in claim 17, wherein said deviation calculating step comprises the step of: counting a duration when the output of said pull-up type input circuit is between said first and third levels, thereby determining that said deviation is small when said duration is larger than a first predetermined duration, and that said deviation is large when said duration is larger than a second predetermined duration.
Claim 23
Dependent Claim
63 words
A method as set forth in claim 15, further comprising the steps of: determining whether or not the output of said pull-up type input circuit is higher than a fourth level higher than said first level; and determining that said air-fuel ratio sensor is in a nonactivation state when the output of said pull-up type input circuit is higher than said fourth level.
Claim 24
Dependent Claim
69 words
A method as set forth in claim 15, wherein said pull-up type input circuit comprises: a resistor connected between the output of said air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.
Claim 25
Dependent Claim
49 words
A method as set forth in claim 15, wherein said actual air-fuel ratio adjusting step comprises the steps of: calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor; and adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 26
Independent Claim
277 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, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising: means for determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher than a rich state level of said pull-up type input circuit after said engine is warmed-up; means for determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; means for determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; means for determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; means for determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and means for adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state.
Claim 27
Independent Claim
277 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, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising: means for determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher than a rich state level of said pull-up type input circuit after said engine is warmed-up; means for determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; means for determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; means for determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; means for determining that said downstream-side air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and means for adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state.
Claim 28
Dependent Claim
125 words
An apparatus as set forth in claim 24, wherein said air-fuel ratio determining means comprises: means for determining whether or not a predetermined time has elapsed after the output of said pull-up type input circuit becomes lower than said first level; means for determining whether or not the output of said pull-up type input circuit is higher than a third level between said first and second levels after said predetermined time has elapsed, thereby determining that the air-fuel ratio of said engine is rich when the output of said pull-up type input circuit is higher than said third level, and that the air-fuel ratio of said engine is lean when the output of said pull-up type input circuit is not higher than said third level.
Claim 29
Dependent Claim
91 words
An apparatus as set forth in claim 24, wherein said air-fuel ratio determining means comprises means for calculating a variation of the output of said pull-up type input circuit after the output of said pull-up type input circuit becomes lower than said first level, thereby determining that the air-fuel ratio of said engine is lean when said variation is larger than a first predetermined valve, and that the air-fuel ratio of said engine is rich when said deviation is smaller than a second predetermined valve smaller than said first predetermined valve.
Claim 30
Dependent Claim
32 words
An apparatus as set forth in claim 26, wherein said deviation is calculated during a predetermined interval after the output of said pull-up type input circuit becomes lower than said first level.
Claim 31
Dependent Claim
20 words
An apparatus as set forth in claim 26, wherein said deviation is calculated during two or more successive predetermined intervals.
Claim 32
Dependent Claim
68 words
An apparatus as set forth in claim 26, wherein said deviation calculating means comprises: means for counting a duration when the output of said pull-up type input circuit is between said first and third levels, thereby determining that said deviation is small when said duration is larger than a first predetermined duration, and that said deviation is large when said duration is larger than a second predetermined duration.
Claim 33
Dependent Claim
65 words
An apparatus as set forth in claim 24, further comprising: means for determining whether or not the output of said pull-up type input circuit is higher than a fourth level higher than said first level; and means for determining that said downstream-side air-fuel ratio sensor is in a non-activation state when the output of said pull-up type input circuit is higher than said fourth level.
Claim 34
Dependent Claim
71 words
An apparatus as set forth in claim 24, wherein said pull-up type input circuit comprises: a resistor connected between an output of said downstream-side air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said downstream-side air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.
Claim 35
Dependent Claim
75 words
An apparatus as set forth in claim 24, wherein said actual air-fuel ratio adjusting means comprises: means for calculating a first air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor; means for calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and means for adjusting said actual air-fuel ratio in accordance with said first and second air-fuel ratio correction amounts.
Claim 36
Dependent Claim
78 words
An apparatus as set forth in claim 24, wherein said actual air-fuel ratio adjusting 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; means for calculating an 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; and means for adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 37
Dependent Claim
85 words
An apparatus as set forth in claim 33, 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 38
Dependent Claim
75 words
An apparatus as set forth in claim 33, 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 39
Dependent Claim
65 words
An apparatus as set forth in claim 33, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time 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 for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the lean side.
Claim 40
Dependent Claim
49 words
An apparatus as set forth in claim 33, 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 41
Independent Claim
265 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising: means for determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher rich state level of said pull-up type input after said engine is warmed-up; means for determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; means for determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; means for determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; means for determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and means for adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state.
Claim 42
Independent Claim
265 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising: means for determining whether or not an output of said pull-up type input circuit is lower than a first level which is slightly higher rich state level of said pull-up type input after said engine is warmed-up; means for determining whether the air-fuel ratio of said engine is rich or lean in accordance with the output of said pull-up type input circuit; means for determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said first level and the air-fuel ratio of said engine is rich; means for determining whether or not the output of said pull-up type input circuit is lower than a second level lower than said first level; means for determining that said air-fuel ratio sensor is in an activation state when the output of said pull-up type input circuit is lower than said second level, and the air-fuel ratio of said engine is lean; and means for adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state.
Claim 43
Dependent Claim
125 words
An apparatus as set forth in claim 38, wherein said air-fuel ratio determining means comprises: means for determining whether or not a predetermined time has elapsed after the output of said pull-up type input circuit becomes lower than said first level; means for determining whether or not the output of said pull-up type input circuit is higher than a third level between said first and second levels after said predetermined time has elapsed, thereby determining that the air-fuel ratio of said engine is rich when the output of said pull-up type input circuit is higher than said third level, and that the air-fuel ratio of said engine is lean when the output of said pull-up type input circuit is not higher than said third level.
Claim 44
Dependent Claim
91 words
An apparatus as set forth in claim 38, wherein said air-fuel ratio determining means comprises means for calculating a variation of the output of said pull-up type input circuit after the output of said pull-up type input circuit becomes lower than said first level, thereby determining that the air-fuel ratio of said engine is lean when said variation is larger than a first predetermined value, and that the air-fuel ratio of said engine is rich when said deviation is smaller than a second predetermined value smaller than said first predetermined value.
Claim 45
Dependent Claim
32 words
An apparatus as set forth in claim 40, wherein said deviation is calculated during a predetermined interval after the output of said pull-up type input circuit becomes lower than said first level.
Claim 46
Dependent Claim
20 words
An apparatus as set forth in claim 40, wherein said deviation is calculated during two or more successive predetermined intervals.
Claim 47
Dependent Claim
68 words
An apparatus as set forth in claim 40, wherein said deviation calculating means comprises: means for counting a duration when the output of said pull-up type input circuit is between said first and third levels, thereby determining that said deviation is small when said duration is larger than a first predetermined duration, and that said deviation is large when said duration is larger than a second predetermined duration.
Claim 48
Dependent Claim
64 words
An apparatus as set forth in claim 38, further comprising: means for determining whether or not the output of said pull-up type input circuit is higher than a fourth level higher than said first level; and means for determining that said air-fuel ratio sensor is in a nonactivation state when the output of said pull-up type input circuit is higher than said fourth level.
Claim 49
Dependent Claim
69 words
An apparatus as set forth in claim 38, wherein said pull-up type input circuit comprises: a resistor connected between the output of said air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.
Claim 50
Dependent Claim
50 words
An apparatus as set forth in claim 38, wherein said actual air-fuel ratio adjusting means comprises: means for calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor; and means for adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
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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) | 1993-11-19 | 1994-05-21 | 1994-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-19 | 1998-05-21 | 1998-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-19 | 2002-05-21 | 2002-11-20 | $7700.00 | Window Closed / Lapsed |