US4817384A
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: 1987-08-11
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Granted: 1989-04-04
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Expires: 2007-08-11
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. The air-fuel ratio correction amount is guarded within a predetermined range. When this correction amount reaches the maximum or minimum value of the range, the calculation of the air-fuel ratio correction amount by the output of the downstream-side air-fuel ratio sensor is prohibited.
Inventors
- 👤 Atsuo Okumura
- 👤 Masato Ujino
- 👤 Takashi Kawase
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:53
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 60
Claim 1
Independent Claim
173 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: calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; guarding said air-fuel ratio correction amount within a predetermined range; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; determining whether or not said air-fuel ratio correction amount reaches a maximum or minimum value of said predetermined range; and prohibiting a calculation of said air-fuel ratio correction amount by the output of said downstream-side air-fuel ratio sensor while carrying out a correction of said air-fuel ratio correction amount by the output of said upstream-side air-fuel ratio ratio sensor when said air-fuel ratio correction amount reaches the maximum or minimum value of said predetermined range.
Claim 2
Independent Claim
173 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: calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors; guarding said air-fuel ratio correction amount within a predetermined range; adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; determining whether or not said air-fuel ratio correction amount reaches a maximum or minimum value of said predetermined range; and prohibiting a calculation of said air-fuel ratio correction amount by the output of said downstream-side air-fuel ratio sensor while carrying out a correction of said air-fuel ratio correction amount by the output of said upstream-side air-fuel ratio ratio sensor when said air-fuel ratio correction amount reaches the maximum or minimum value of said predetermined range.
Claim 3
Dependent Claim
75 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, thereby calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 4
Dependent Claim
134 words
A method as set forth in claim 2, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level, by comparing this output with a rich determination level when the output of said downstream-side air-fuel ratio sensor indicates a lean level; and determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level, thereby calculating said second air-fuel ratio correction amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 5
Dependent Claim
63 words
A method as set forth in claim 3, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich.
Claim 6
Dependent Claim
63 words
A method as set forth in claim 3, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich.
Claim 7
Dependent Claim
159 words
A method as set forth in claim 2, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: determining whether the output of said downstream-side air-fuel ratio sensor is ascending or descending; determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comprising this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending state; and determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states, thereby calculating said second air-fuel ratio correction amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 8
Dependent Claim
79 words
A method as set forth in claim 6, wherein said rich determining step further comprises a step of determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with said rich determination level; and wherein said lean determining step further comprises a step of determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with said lean determination level.
Claim 9
Dependent Claim
106 words
A method as set forth in claim 6, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich, and said method further comprising the steps of: carrying out said rich determining step when the output of said downstream-side air-fuel ratio sensor is ascending; and carrying out said lean determining step when the output of said downstream-side air-fuel ratio sensor is descending.
Claim 10
Dependent Claim
106 words
A method as set forth in claim 6, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich, and said method further comprising the steps of: carrying out said rich determining step when the output of said downstream-side air-fuel ratio sensor is descending; and carrying out said lean determining step when the output of said downstream-side air-fuel ratio sensor is ascending.
Claim 11
Dependent Claim
97 words
A method as set forth in claim 6, further comprising the steps of: prohibiting the calculation of said second air-fuel ratio correction amount when the output of said downstream-side air-fuel ratio sensor indicates said lean level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and prohibiting the calculation of said second air-fuel ratio correction amount when the output of said downstream-side air-fuel ratio sensor indicates said rich level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states.
Claim 12
Dependent Claim
77 words
A method as set forth in claim 2, wherein said second air-fuel ratio correction amount calculating step comprises the steps of: comparing the output of said downstream-side air-fuel ratio sensor with a reference voltage; and renewing said reference voltage in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said second air-fuel ratio correction amount in accordance with the comparison result of the output of said downstream-side air-fuel ratio sensor with said reference voltage.
Claim 13
Dependent Claim
143 words
A method as set forth in claim 11, wherein said reference voltage renewing step comprises the steps of: determining whether or not the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; subtracting a first predetermined value from the output of said downstream-side air-fuel ratio sensor to obtain a first value, when the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; replacing said reference voltage with said first value only when said first value is higher than said reference voltage; adding a second predetermined value to the output of said downstream-side air-fuel ratio sensor to obtain a second value, when the output of said downstream-side air-fuel ratio sensor is not higher than said reference voltage; replacing said reference voltage with said second value only when said first value is lower than said reference voltage.
Claim 14
Dependent Claim
24 words
A method as set forth in claim 12, wherein said first and second predetermined values are dependent upon a load parameter of said engine.
Claim 15
Dependent Claim
63 words
A method as set forth in claim 1, wherein said air-fuel ratio correction amount calculating step comprises a step of calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter.
Claim 16
Dependent Claim
134 words
A method as set forth in claim 14, wherein said air-fuel ratio feedback control parameter calculating step comprises the steps of: determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level; and determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level, thereby calculating said air-fuel ratio feedback control amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 17
Dependent Claim
63 words
A method as set forth in claim 15, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich.
Claim 18
Dependent Claim
63 words
A method as set forth in claim 15, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich.
Claim 19
Dependent Claim
159 words
A method as set forth in claim 14, wherein said air-fuel ratio feedback control parameter calculating step comprises the steps of: determining whether the output of said downstream-side air-fuel ratio sensor is ascending or descending; determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and determining whether or not the output of said downstream side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states, thereby calculating said air-fuel ratio feedback control in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 20
Dependent Claim
80 words
A method as set forth in claim 18, wherein said rich determining step further comprises a step of determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with said rich determination level; and wherein said lean determinining step further comprises a step of determining whether or not the output of said downstream-side air fuel ratio sensor indicates a rich level by comparing this output with said lean determination level.
Claim 21
Dependent Claim
106 words
A method as set forth in claim 18, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich, and said method further comprising the steps of: carrying out said rich determining step when the output of said downstream-side air-fuel ratio sensor is ascending; and carrying out said lean determining step when the output of said downstream-side air-fuel ratio sensor is descending,
Claim 22
Dependent Claim
106 words
A method as set forth in claim 18, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich, and said method further comprising the steps of: carrying out said rich determining step when the output of said downstream-side air-fuel ratio sensor is descending; and carrying out said lean determining step when the output of said downstream-side air-fuel ratio sensor is ascending.
Claim 23
Dependent Claim
97 words
A method as set forth in claim 18, further comprising the steps of: prohibiting the calculation of said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates said lean level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and prohibiting the calculation of said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates said rich level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states,
Claim 24
Dependent Claim
77 words
A method as set forth in claim 14, wherein said air-fuel ratio feedback control parameter calculating step comprises the steps of: comparing the output of said downstream-side air-fuel ratio sensor with a reference voltage; and renewing said reference voltage in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio feedback control parameter in accordance with the comparison result of the output of said downstream-side air-fuel ratio sensor with said reference voltage.
Claim 25
Dependent Claim
143 words
A method as set forth in claim 23, wherein said reference voltage renewing step comprises the steps of: determining whether or not the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; subtracting a first predetermined value from the output of said downstream-side air-fuel ratio sensor to obtain a first value, when the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; replacing said reference voltage with said first value only when said first value is higher than said reference voltage; adding a second predetermined value to the output of said downstream-side air-fuel ratio sensor to obtain a second value, when the output of said downstream-side air-fuel ratio sensor is not higher than said reference voltage; replacing said reference voltage with said second value only when said first value is lower than said reference voltage.
Claim 26
Dependent Claim
24 words
A method as set forth in claim 24, wherein said first and second predetermined values are dependent upon a load parameter of said engine.
Claim 27
Dependent Claim
85 words
A method as set forth in claim 14, 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 of 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 28
Dependent Claim
75 words
A method as set forth in claim 14, 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 29
Dependent Claim
67 words
A method as set forth in claim 14, 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 30
Dependent Claim
49 words
A method as set forth in claim 14, 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 31
Independent Claim
180 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 calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air fuel ratio sensors; means for guarding said air-fuel ratio correction amount within a predetermined range; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; means for determining whether or not said air-fuel ratio correction amount reaches a maximum or minimum value of said predetermined range; and means for prohibiting a calculation of said air-fuel ratio correction amount by the output of said downstream-side air-fuel ratio sensor and carrying out a correction of said air-fuel ratio correction amount by the output of said upstream-side air-fuel ratio sensor when said air-fuel ratio correction amount reaches the maximum or minimum value of said predetermined range.
Claim 32
Independent Claim
180 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 calculating an air-fuel ratio correction amount in accordance with the outputs of said upstream-side and downstream-side air fuel ratio sensors; means for guarding said air-fuel ratio correction amount within a predetermined range; means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount; means for determining whether or not said air-fuel ratio correction amount reaches a maximum or minimum value of said predetermined range; and means for prohibiting a calculation of said air-fuel ratio correction amount by the output of said downstream-side air-fuel ratio sensor and carrying out a correction of said air-fuel ratio correction amount by the output of said upstream-side air-fuel ratio sensor when said air-fuel ratio correction amount reaches the maximum or minimum value of said predetermined range.
Claim 33
Dependent Claim
76 words
An apparatus as set forth in claim 30, 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, thereby calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts.
Claim 34
Dependent Claim
135 words
An apparatus as set forth in claim 31, wherein said second air-fuel ratio correction amount calculating step comprises: means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level, thereby calculating said second air-fuel ratio correction amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 35
Dependent Claim
63 words
An apparatus as set forth in claim 32, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich.
Claim 36
Dependent Claim
63 words
An apparatus as set forth in claim 32, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich.
Claim 37
Dependent Claim
163 words
An apparatus as set forth in claim 31, wherein said second air-fuel ratio correction amount calculating step comprises: means for determining whether the output of said downstream-side air-fuel ratio sensor is ascending or descending; means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states, thereby calculating a said second air-fuel ratio correction amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 38
Dependent Claim
79 words
An apparatus as set forth in claim 35, wherein said rich determining step further comprises a step of determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with said rich determination level; and wherein said lean determining step further comprises a step of determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with said lean determination level.
Claim 39
Dependent Claim
107 words
An apparatus as set forth in claim 35, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich, and said apparatus further comprising: means for carrying out said rich determining means when the output of said downstream-side air-fuel ratio sensor is ascending; and means for carrying out said lean determining means when the output of said downstream-side air-fuel ratio sensor is descending.
Claim 40
Dependent Claim
107 words
An apparatus as set forth in claim 35, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich, and said apparatus further comprising; means for carrying out said rich determining means when the output of said downstream-side air-fuel ratio sensor is descending; and means for carrying out said lean determining means when the output of said downstream-side air-fuel ratio sensor is ascending.
Claim 41
Dependent Claim
98 words
An apparatus as set forth in claim 35, further comprising: means for prohibiting the calculation of said second air-fuel ratio correction amount when the output of said downstream-side air-fuel ratio sensor indicates said lean level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and means for prohibiting the calculation of said second air-fuel ratio correction amount when the output of said downstream-side air-fuel ratio sensor indicates said rich level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states.
Claim 42
Dependent Claim
78 words
An apparatus as set forth in claim 31, wherein said second air-fuel ratio correction amount calculating means comprises: means for comparing the output of said downstream-side air-fuel ratio sensor with a reference voltage; and means for renewing said reference voltage in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said second air-fuel ratio correction amount in accordance with the comparison result of the output of said downstream-side air-fuel ratio sensor with said reference voltage.
Claim 43
Dependent Claim
150 words
An apparatus as set forth in claim 40, wherein said reference voltage renewing means comprises: means for determining whether or not the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; means for subtracting a first predetermined value from the output of said downstream-side air-fuel ratio sensor to obtain a first value, when the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; means for replacing said reference voltage with said first value only when said first value is higher than said reference voltage; means for adding a second predetermined value to the output of said downstream-side air-fuel ratio sensor to obtain a second value, when the output of said downstream-side air-fuel ratio sensor is not higher than said reference voltage; means for replacing said reference voltage with said second value only when said first value is lower than said reference voltage.
Claim 44
Dependent Claim
24 words
An apparatus as set forth in claim 41, wherein said first and second predetermined values are dependent upon a load parameter of said engine.
Claim 45
Dependent Claim
62 words
An apparatus as set forth in claim 30, wherein said air-fuel ratio correction amount calculating means comprises means for calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter.
Claim 46
Dependent Claim
135 words
An apparatus as set forth in claim 43, wherein said air-fuel ratio feedback control parameter calculating step comprises: means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor indicates a lean level, thereby calculating said air-fuel ratio feedback control amount in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 47
Dependent Claim
63 words
An apparatus as set forth in claim 44, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich.
Claim 48
Dependent Claim
63 words
An apparatus as set forth in claim 44, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich.
Claim 49
Dependent Claim
162 words
An apparatus as set forth in claim 43, wherein said air-fuel ratio feedback control parameter calculating means comprises: means for determining whether the output of said downstream-side air-fuel ratio sensor is ascending or descending; means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with a rich determination level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending state; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with a lean determination level which is different from said rich determination level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states, thereby calculating said air-fuel ratio feedback control parameter in accordance with whether the output of said downstream-side air-fuel ratio sensor indicates a rich level or a lean level.
Claim 50
Dependent Claim
77 words
An apparatus as set forth in claim 47, wherein said rich determining means further comprises means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a lean level by comparing this output with said rich determination level; and wherein said lean determining means further comprises means for determining whether or not the output of said downstream-side air-fuel ratio sensor indicates a rich level by comparing this output with said lean determination level.
Claim 51
Dependent Claim
107 words
An apparatus as set forth in claim 47, wherein said rich determination level is lower than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is rich, and said apparatus further comprising; means for carrying out said rich determining step when the output of said downstream-side air-fuel ratio sensor is ascending; and means for carrying out said lean determining step when the output of said downstream-side air-fuel ratio sensor is descending.
Claim 52
Dependent Claim
107 words
An apparatus as set forth in claim 47, wherein said rich determination level is higher than said lean determination level, in the case where the output of said downstream-side air-fuel ratio sensor is at a high level when the air-fuel ratio is lean and the output of said downstream-side air-fuel ratio sensor is at a low level when the air-fuel ratio is rich, and said apparatus further comprising: means for carrying out said rich determining means when the output of said downstream-side air-fuel ratio sensor is descending; and means for carrying out said lean determining means when the output of said downstream-side air-fuel ratio sensor is ascending.
Claim 53
Dependent Claim
100 words
An apparatus as set forth in claim 47, which further comprises a means for prohibiting the calculation of said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates said lean level, when the output of said downstream-side air-fuel ratio sensor is in one of the ascending and descending states; and means for prohibiting the calculation of said air-fuel ratio feedback control parameter when the output of said downstream-side air-fuel ratio sensor indicates said rich level, when the output of said downstream-side air-fuel ratio sensor is in the other of the ascending and descending states.
Claim 54
Dependent Claim
78 words
An apparatus as set forth in claim 43, wherein said air-fuel ratio feedback control parameter calculating means comprises: means for comparing the output of said downstream-side air-fuel ratio sensor with a reference voltage; and means for renewing said reference voltage in accordance with the output of said downstream-side air-fuel ratio sensor, thereby calculating said air-fuel ratio feedback control parameter in accordance with the comparison result of the output of said downstream-side air-fuel ratio sensor with said reference voltage.
Claim 55
Dependent Claim
150 words
An apparatus as set forth in claim 52, wherein said reference voltage renewing step comprises: means for determining whether or not the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; means for subtracting a first predetermined value from the output of said downstream-side air-fuel ratio sensor to obtain a first value, when the output of said downstream-side air-fuel ratio sensor is higher than said reference voltage; means for replacing said reference voltage with said first value only when said first value is higher than said reference voltage; means for adding a second predetermined value to the output of said downstream-side air-fuel ratio sensor to obtain a second value, when the output of said downstream-side air-fuel ratio sensor is not higher than said reference voltage; means for replacing said reference voltage with said second value only when said first value is lower than said reference voltage.
Claim 56
Dependent Claim
24 words
An apparatus as set forth in claim 53, wherein said first and second predetermined values are dependent upon a load parameter of said engine.
Claim 57
Dependent Claim
85 words
A method as set forth in claim 43, 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 58
Dependent Claim
75 words
A method as set forth in claim 43, 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 usptream-side air-fuel ratio sensor is on the lean side.
Claim 59
Dependent Claim
67 words
A method as set forth in claim 43, 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 60
Dependent Claim
49 words
A method as set forth in claim 43, 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.
References Cited (Backward Citations)
US3939654A
Cited
JPS52102934A
Cited
US4027477A
Cited
JPS53103796A
Cited
US4130095A
Cited
JPS5537562A
Cited
US4251989A
Cited
US4235204A
Cited
JPS5732773A
Cited
JPS5732774A
Cited
JPS5732772A
Cited
US4462373A
Cited
JPS5827848A
Cited
US4475517A
Cited
JPS5848755A
Cited
JPS5848756A
Cited
JPS5853661A
Cited
JPS5872646A
Cited
JPS5872647A
Cited
JPS58135343A
Cited
JPS58150039A
Cited
JPS58150038A
Cited
US4571683A
Cited
JPS58152147A
Cited
JPS5932644A
Cited
US4539958A
Cited
JPS59206638A
Cited
JPS601340A
Cited
US4561400A
Cited
US4625698A
Cited
JPH0626138A
Cited
JPH0653635A
Cited
JPH06134330A
Cited
JPH06153436A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |