US4881368A
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: 1988-02-05
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Granted: 1989-11-21
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Expires: 2008-02-05
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 all of the feedback control conditions for the downstream-side air-fuel ratio sensor are satisfied, a speed of renewal of the air-fuel ratio correction amount in accordance with the output of the downstream-side air-fuel ratio sensor is lowered before the output of the downstream-side air-fuel ratio sensor is reversed or for a predetermined time period.
Inventors
- 👤 Takayuki Demura
- 👤 Kohei Igarashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:25
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 98
Claim 1
Independent Claim
183 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when all of said air-fuel ratio feedback control conditions are satisfied; determining whether or not the output of said downstream-side air-fuel ratio sensor is reversed; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 2
Independent Claim
183 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when all of said air-fuel ratio feedback control conditions are satisfied; determining whether or not the output of said downstream-side air-fuel ratio sensor is reversed; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 3
Dependent Claim
30 words
A method as set forth in claim 1, wherein said renewal speed lowering is carried out only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 4
Dependent Claim
81 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 output of said upstream-side air-fuel ratio sensor; and calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor, said air-fuel ratio correction amount calculating step calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 5
Dependent Claim
64 words
A method as set forth in claim 3, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 6
Dependent Claim
98 words
A method as set forth in claim 3, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: remarkably increasing said second air-fuel ratio correction amount by a rich skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side; and remarkably decreasing said second air-fuel ratio correction amount by a lean skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side, said renewal speed lowering step reducing said rich and lean skip amounts.
Claim 7
Dependent Claim
85 words
A method as set forth in claim 3, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: gradually increasing said second air-fuel ratio correction amount by a rich integration amount when the output of said downstream-side air-fuel ratio sensor indicates a lean state; and gradually decreasing said air-fuel ratio correction amount by a lean integration amount when the output of said downstream-side air-fuel ratio sensor indicates a rich state, said renewal speed lowering step reducing said rich and lean integration amounts.
Claim 8
Dependent Claim
65 words
A method as set forth in claim 3, further comprising the steps of: lowering a renewal speed of said second air-fuel ratio correction amount after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and imposing an allowable range on said second air-fuel ratio correction amount.
Claim 9
Dependent Claim
35 words
A method as set forth in claim 7, wherein said allowable range imposing step imposes said second air-fuel ratio correction amount only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 10
Dependent Claim
44 words
A method as set forth in claim 7, wherein said allowable range imposing step imposes a decreased allowable range in accordance with said second air-fuel ratio correction amount immediately before all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 11
Dependent Claim
51 words
A method as set forth in claim 7, wherein said allowable range imposing step imposes a decreased allowable range in accordance with a maximum value and a minimum value of said second air-fuel ratio correction amount when all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 12
Dependent Claim
59 words
A method as set forth in claim 7, wherein said allowable range imposing step imposes a decreased allowable range in accordance with a blunt value of local maximum values and a blunt value of local minimum values of said second air-fuel ratio correction amount when all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 13
Dependent Claim
63 words
A method as set forth in claim 1, 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.
Claim 14
Dependent Claim
64 words
A method as set forth in claim 12, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameter is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 15
Dependent Claim
65 words
A method as set forth in claim 12, further comprising the steps of: lowering a renewal speed of said air-fuel ratio feedback control parameter after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and imposing an allowable range on said air-fuel ratio feedback control parameter.
Claim 16
Dependent Claim
35 words
A method as set forth in claim 14, wherein said allowable range imposing step imposes said air-fuel ratio feedback control parameter only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 17
Dependent Claim
44 words
A method as set forth in claim 14, wherein said allowable range imposing step imposes a decreased allowable range in accordance with said air-fuel ratio feedback control parameter amount immediately before all the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 18
Dependent Claim
51 words
A method as set forth in claim 14, wherein said allowable range imposing step imposes a decreased allowable range in accordance with a maximum value and a minimum value of said air-fuel ratio feedback control parameter when all of the feedback control conditions by said downstream-side air-fuel ratio sensor are satisfied.
Claim 19
Dependent Claim
59 words
A method as set forth in claim 14, wherein said allowable range imposing step imposes a decreased allowable range in accordance with a blunt value of local maximum values and a blunt value of local minimum values of said air-fuel ratio feedback control parameter when all of the feedback control conditions by said downstream-side air-fuel ratio sensor are satisfied.
Claim 20
Dependent Claim
85 words
A method 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 21
Dependent Claim
75 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 correction amount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 22
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 23
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.
Claim 24
Independent Claim
163 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 a specific component in the exhaust gas, comprising the steps of: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when all of said air-fuel ratio feedback control conditions are satisfied; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel sensor for a predetermined time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 25
Independent Claim
163 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 a specific component in the exhaust gas, comprising the steps of: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when all of said air-fuel ratio feedback control conditions are satisfied; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel sensor for a predetermined time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 26
Dependent Claim
81 words
A method as set forth in claim 23, 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 output of said upstream-side air-fuel ratio sensor; and calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor, said air-fuel ratio correction amount calculating step calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 27
Dependent Claim
64 words
A method as set forth in claim 24, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 28
Dependent Claim
98 words
A method as set forth in claim 24, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: remarkably increasing said second air-fuel ratio correction amount by a rich skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side; and remarkably decreasing said second air-fuel ratio correction amount by a lean skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side, said renewal speed lowering step reducing said rich and lean skip amounts.
Claim 29
Dependent Claim
85 words
A method as set forth in claim 24, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: gradually increasing said second air-fuel ratio correction amount by a rich integration amount when the output of said downstream-side air-fuel ratio sensor indicates a lean state; and gradually decreasing said air-fuel ratio correction amount by a lean integration amount when the output of said downstream-side air-fuel ratio sensor indicates a rich state, said renewal speed lowering step reducing said rich and lean integration amounts.
Claim 30
Dependent Claim
63 words
A method as set forth in claim 23, 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.
Claim 31
Dependent Claim
64 words
A method as set forth in claim 28, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameter is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 32
Dependent Claim
85 words
A method as set forth in claim 28, 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 33
Dependent Claim
75 words
A method as set forth in claim 28, 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 34
Dependent Claim
67 words
A method as set forth in claim 28, 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 35
Dependent Claim
49 words
A method as set forth in claim 28, 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 36
Independent Claim
190 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 when all of said air-fuel ratio feedback control conditions are satisfied; means for determining whether or not the output of said downstream-side air-fuel ratio sensor is reversed; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 37
Independent Claim
190 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 when all of said air-fuel ratio feedback control conditions are satisfied; means for determining whether or not the output of said downstream-side air-fuel ratio sensor is reversed; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 38
Dependent Claim
32 words
An apparatus as set forth in claim 34, wherein said renewal speed lowering means lowers said renewal speed only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 39
Dependent Claim
82 words
An apparatus as set forth in claim 34, wherein said air-fuel ratio correction amount calculating step comprises: means for calculating a first air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor; and means for calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor, said air-fuel ratio correction amount calculating means calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 40
Dependent Claim
64 words
An apparatus as set forth in claim 36, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 41
Dependent Claim
99 words
An apparatus as set forth in claim 36, wherein said second air-fuel ratio correction amount calculating means comprises: means for remarkably increasing said second air-fuel ratio correction amount by a rich skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side; and means for remarkably decreasing said second air-fuel ratio correction amount by a lean skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side, said renewal speed lowering means reducing said rich and lean skip amounts.
Claim 42
Dependent Claim
86 words
An apparatus as set forth in claim 36, wherein said second air-fuel ratio correction amount calculating means comprises: means for gradually increasing said second air-fuel ratio correction amount by a rich integration amount when the output of said downstream-side air-fuel ratio sensor indicates a lean state; and means for gradually decreasing said air-fuel ratio correction amount by a lean integration amount when the output of said downstream-side air-fuel ratio sensor indicates a rich state, said renewal speed lowering means reducing said rich and lean integration amounts.
Claim 43
Dependent Claim
66 words
An apparatus as set forth in claim 36, further comprising: means for lowering a renewal speed of said second air-fuel ratio correction amount after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and means for imposing an allowable range on said second air-fuel ratio correction amount.
Claim 44
Dependent Claim
35 words
An apparatus as set forth in claim 40, wherein said allowable range imposing means imposes said second air-fuel ratio correction amount only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 45
Dependent Claim
44 words
An apparatus as set forth in claim 40, wherein said allowable range imposing means imposes a decreased allowable range in accordance with said second air-fuel ratio correction amount immediately before all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 46
Dependent Claim
51 words
An apparatus as, set forth in claim 40, wherein said allowable range imposing means imposes a decreased allowable range in accordance with a maximum value and a minimum value of said second air-fuel ratio correction amount when all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 47
Dependent Claim
59 words
An apparatus as set forth in claim 40, wherein said allowable range imposing means imposes a decreased allowable range in accordance with a blunt value of local maximum values and a blunt value of local minimum values of said second air-fuel ratio correction amount when all of the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 48
Dependent Claim
64 words
An apparatus as set forth in claim 34, wherein said air-fuel ratio correction amount calculating step 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.
Claim 49
Dependent Claim
64 words
An apparatus as set forth in claim 45, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameter is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 50
Dependent Claim
66 words
An apparatus as set forth in claim 45, further comprising: means for lowering a renewal speed of said air-fuel ratio feedback control parameter after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of said downstream-side air-fuel ratio sensor is reversed; and means for imposing an allowable range on said air-fuel ratio feedback control parameter.
Claim 51
Dependent Claim
35 words
An apparatus as set forth in claim 47, wherein said allowable range imposing means imposes said air-fuel ratio feedback control parameter only when the output of said downstream-side air-fuel ratio sensor indicates a lean state.
Claim 52
Dependent Claim
44 words
An apparatus as set forth in claim 47, wherein said allowable range imposing means imposes a decreased allowable range in accordance with said air-fuel ratio feedback control parameter amount immediately before all the feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied.
Claim 53
Dependent Claim
50 words
An apparatus as set forth in claim 47, wherein said allowable imposing means imposes a decreased allowable range in accordance with a maximum value and a minimum value of said air-fuel ratio feedback control parameter when all of the feedback control conditions by said downstream-side air-fuel ratio sensor are satisfied.
Claim 54
Dependent Claim
59 words
An apparatus as set forth in claim 47, wherein said allowable range imposing means imposes a decreased allowable range in accordance with a blunt value of local maximum values and a blunt value of local minimum values of said air-fuel ratio feedback control parameter when all of the feedback control conditions by said downstream-side air-fuel ratio sensor are satisfied.
Claim 55
Dependent Claim
85 words
An apparatus as set forth in claim 45, 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 aid downstream-side air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 56
Dependent Claim
75 words
An apparatus as set forth in claim 45, 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 57
Dependent Claim
67 words
An apparatus as set forth in claim 45, 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 58
Dependent Claim
49 words
An apparatus as set forth in claim 45, 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 59
Independent Claim
161 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having ca 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 when all of said air-fuel ratio feedback control conditions are satisfied; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time period commencing when all of the air-fuel ratio sensor are satisfied; and mean as for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 60
Independent Claim
161 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having ca 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 when all of said air-fuel ratio feedback control conditions are satisfied; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time period commencing when all of the air-fuel ratio sensor are satisfied; and mean as for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 61
Dependent Claim
82 words
An apparatus as set forth in claim 56, wherein said air-fuel ratio correction amount calculating 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; and means for calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor, said air-fuel ratio correction amount calculating step calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 62
Dependent Claim
64 words
An apparatus as set forth in claim 57, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 63
Dependent Claim
99 words
An apparatus as set forth in claim 57, wherein said second air-fuel ratio correction amount calculating step comprises: means for remarkably increasing said second air-fuel ratio correction amount by a rich skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side; and means for remarkably decreasing said second air-fuel ratio correction amount by a lean skip amount when the output of said downstream-side air-fuel ratio sensor is switched from the lean side to the rich side, said renewal speed lowering step reducing said rich and lean skip amounts.
Claim 64
Dependent Claim
86 words
An apparatus as set forth in claim 57, wherein said second air-fuel ratio correction amount calculating means comprises: means for gradually increasing said second air-fuel ratio correction amount by a rich integration amount when the output of said downstream-side air-fuel ratio sensor indicates a lean state; and means for gradually decreasing said air-fuel ratio correction amount by a lean integration amount when the output of said downstream-side air-fuel ratio sensor indicates a rich state, said renewal speed lowering step reducing said rich and lean integration amounts.
Claim 65
Dependent Claim
67 words
An apparatus as set forth in claim 56, wherein said air-fuel ratio correction amount calculating means comprises the steps of: 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.
Claim 66
Dependent Claim
64 words
An apparatus as set forth in claim 61, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameter is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 67
Dependent Claim
85 words
An apparatus as set forth in claim 61, 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 68
Dependent Claim
75 words
An apparatus as set forth in claim 61, 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 69
Dependent Claim
67 words
An apparatus as set forth in claim 61, 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 70
Dependent Claim
49 words
An apparatus as set forth in claim 61, 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 71
Independent Claim
196 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied: 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; calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; imposing an allowable range on said second air-fuel ratio correction amount; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 72
Independent Claim
196 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied: 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; calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; imposing an allowable range on said second air-fuel ratio correction amount; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 73
Dependent Claim
65 words
The method of claim 67 further comprising the step of determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the step of imposing an allowable range includes imposing an allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 74
Dependent Claim
83 words
The method of claim 67, further comprising the step of determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the step of imposing an allowable range includes imposing a first allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed, and imposing a second allowable range after the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 75
Independent Claim
244 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range ons aid second air-fuel ratio correction amount; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the step of imposing an allowable range includes imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and imposing a second allowable range upon expiration of the time period.
Claim 76
Independent Claim
244 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range ons aid second air-fuel ratio correction amount; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the step of imposing an allowable range includes imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and imposing a second allowable range upon expiration of the time period.
Claim 77
Dependent Claim
65 words
A method as set forth in claim 70, wherein, when at least one of the feedback control conditions for said downstream-side air fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 78
Independent Claim
162 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; imposing an allowable range on said second air-fuel ratio feedback control parameter; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 79
Independent Claim
162 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: determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; imposing an allowable range on said second air-fuel ratio feedback control parameter; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 80
Dependent Claim
65 words
The method of claim 72, further comprising the step of determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the step of imposing an allowable range includes imposing an allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 81
Dependent Claim
83 words
The method of claim 72, further comprising the step of determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the step of imposing an allowable range includes imposing a first allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed, and imposing a second allowable range after the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 82
Independent Claim
234 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: determining whether or not all of air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said air-fuel ratio feedback control parameter; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the step of imposing an allowable range includes imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and imposing a second allowable range upon expiration of the time period.
Claim 83
Independent Claim
234 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: determining whether or not all of air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said air-fuel ratio feedback control parameter; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the step of imposing an allowable range includes imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and imposing a second allowable range upon expiration of the time period.
Claim 84
Dependent Claim
65 words
A method as set forth in claim 75, wherein, when at least one of the feedback control conditions for said downstream-side air fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameter is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 85
Independent Claim
207 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; means for calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for imposing an allowable range on said second air-fuel ratio correction amount; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 86
Independent Claim
207 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; means for calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for imposing an allowable range on said second air-fuel ratio correction amount; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 87
Dependent Claim
66 words
The apparatus of claim 77, further comprising means for determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the means for imposing an allowable range includes means for imposing an allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 88
Dependent Claim
84 words
The apparatus of claim 77, further comprising means for determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the means for imposing an allowable range includes means for imposing a first allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed, and imposing a second allowable range after the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 89
Independent Claim
255 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; means for calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; means for lower speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said second air-fuel ratio correction amount; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the means for imposing an allowable range includes means for imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and means for imposing a second allowable range upon expiration of the time period.
Claim 90
Independent Claim
255 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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; means for calculating an air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; means for lower speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said second air-fuel ratio correction amount; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the means for imposing an allowable range includes means for imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and means for imposing a second allowable range upon expiration of the time period.
Claim 91
Dependent Claim
64 words
An apparatus as set forth in claim 80, wherein, when at least one of the feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied, said second air-fuel ratio correction amount is a value of said second air-fuel ratio correction amount immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
Claim 92
Independent Claim
195 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 determining whether or not all air-fuel ratio feedback control conditions from said downstream-side air-fuel ratio sensor are satisfied; 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; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for imposing an allowable range on said second air-fuel ratio feedback control parameter; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 93
Independent Claim
195 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 determining whether or not all air-fuel ratio feedback control conditions from said downstream-side air-fuel ratio sensor are satisfied; 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; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for imposing an allowable range on said second air-fuel ratio feedback control parameter; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 94
Dependent Claim
66 words
The apparatus of claim 82 further comprising means for determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the means for imposing an allowable range includes means for imposing and allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 95
Dependent Claim
85 words
The apparatus of claim 82, further comprising the means for determining whether the output of the downstream-side air-fuel ratio sensor is reversed, and wherein the means for imposing an allowable range includes means for imposing a first allowable range after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied and until the output of the downstream-side air-fuel ratio sensor is reversed, and imposing a second allowable range after the output of the downstream-side air-fuel ratio sensor is reversed.
Claim 96
Independent Claim
283 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 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; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said air-fuel ratio feedback control parameter; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the means for imposing an allowable range includes means for imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and means for imposing a second allowable range upon expiration of the time period.
Claim 97
Independent Claim
283 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 determining whether or not all air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; 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 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; means for lowering a speed of renewal of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor for a time period commencing when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied by imposing an allowable range on said air-fuel ratio feedback control parameter; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; and wherein the means for imposing an allowable range includes means for imposing a first allowable range for the time period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied, and means for imposing a second allowable range upon expiration of the time period.
Claim 98
Dependent Claim
65 words
An apparatus as set forth in claim 85, wherein, when at least one of the feedback control conditions for said downstream-side air fuel ratio sensor is not satisfied, said air-fuel ratio feedback control parameters is a value of said air-fuel ratio feedback control parameter immediately before at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied.
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USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1992-11-20 | 1993-05-22 | 1993-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-20 | 1997-05-22 | 1997-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-20 | 2001-05-22 | 2001-11-21 | $7700.00 | Window Closed / Lapsed |