US5070693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio feedback control system having single air-fuel ratio sensor downstream of or within three-way catalyst converter
Assignee: Toyota Motor Corp
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Filing: 1990-11-20
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Granted: 1991-12-10
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Expires: 2010-11-20
Abstract
Abstract In an air-fuel ratio feedback system including a single air-fuel ratio sensor downstream of or within a three-way catalyst converter, an idling coarse-adjusting term is calculated integrally in accordance with the output of the air-fuel ratio sensor in an idling state of an engine. After the output of the air-fuel ratio sensor is inverted, the idling coarse-adjusting term is first rapidly changed, and thereafter, is slowly changed.
Inventors
- 👤 Mitsuhiro Nada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:53
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1482; F02D41/1486; F02D41/1487; F02D41/1497; F02D41/1498; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F02D2200/00; F02D2200/02; F02D2200/10; F02D2200/1015; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 140
Claim 1
Independent Claim
225 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, when said engine is in the non-idling state.
Claim 2
Independent Claim
225 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, when said engine is in the non-idling state.
Claim 3
Dependent Claim
23 words
A method as set forth in claim 1, wherein said third integration speed is a value between said first and second integration speeds.
Claim 4
Dependent Claim
69 words
A method as set forth in claim 1, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 5
Dependent Claim
32 words
A method as set forth in claim 3, further comprising a step of setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 6
Dependent Claim
37 words
A method as set forth in claim 4, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 7
Dependent Claim
69 words
A method as set forth in claim 1, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 8
Dependent Claim
32 words
A method as set forth in claim 6, further comprising a step of setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 9
Dependent Claim
37 words
A method as set forth in claim 7, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 10
Dependent Claim
38 words
A method as set forth in claim 1, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 11
Dependent Claim
53 words
A method as set forth in claim 1, further comprising the steps of: detecting a transition in said engine from the non-idling state to the idling state; and forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 12
Dependent Claim
32 words
A method as set forth in claim 10, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 13
Dependent Claim
29 words
A method as set forth in claim 10, wherein said transition detecting step detects only a transition from a small load state of said engine to the idling state.
Claim 14
Dependent Claim
69 words
A method as set forth in claim 12, wherein said transition detecting step comprises a step of determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 15
Dependent Claim
86 words
A method as set forth in claim 12, wherein said transition detecting step comprises the steps of: determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value, thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 16
Dependent Claim
41 words
A method as set forth in claim 1, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 17
Dependent Claim
51 words
A method as set forth in claim 15, wherein said self-oscillating term calculating step comprises the steps of: decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 18
Independent Claim
276 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said fine-adjusting term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said fine-adjusting term, when said engine is in the non-idling state.
Claim 19
Independent Claim
276 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said fine-adjusting term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said fine-adjusting term, when said engine is in the non-idling state.
Claim 20
Dependent Claim
23 words
A method as set forth in claim 17, wherein said third integration speed is a value between said first and second integration speeds.
Claim 21
Dependent Claim
69 words
A method as set forth in claim 17, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 22
Dependent Claim
32 words
A method as set forth in claim 19, further comprising a step of setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 23
Dependent Claim
37 words
A method as set forth in claim 20, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 24
Dependent Claim
69 words
A method as set forth in claim 17, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 25
Dependent Claim
32 words
A method as set forth in claim 22, further comprising a step of setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 26
Dependent Claim
37 words
A method as set forth in claim 23, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 27
Dependent Claim
38 words
A method as set forth in claim 17, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 28
Dependent Claim
53 words
A method as set forth in claim 17, further comprising the steps of: detecting a transition in said engine from the non-idling state to the idling state; and forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 29
Dependent Claim
32 words
A method as set forth in claim 26, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 30
Dependent Claim
29 words
A method as set forth in claim 26, wherein said transition detecting step detects only a transition from a small load state of said engine to the idling state.
Claim 31
Dependent Claim
69 words
A method as set forth in claim 28, wherein said transition detecting step comprises a step of determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 32
Dependent Claim
86 words
A method as set forth in claim 28, wherein said transition detecting step comprises the steps of: determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 33
Dependent Claim
41 words
A method as set forth in claim 17, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 34
Dependent Claim
51 words
A method as set forth in claim 31, wherein said self-oscillating term calculating step comprises the steps of: decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 35
Independent Claim
297 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said O 2 storage term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 36
Independent Claim
297 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said O 2 storage term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 37
Dependent Claim
72 words
A method as set forth in claim 33, further comprising the steps of: gradually decreasing said O 2 storage term, when the output of said air-fuel ratio sensor is higher than the first level and said engine is in the non-idling state; and gradually increasing said O 2 storage term, when the output of said air-fuel ratio sensor is lower than the second level and said engine is in the non-idling state.
Claim 38
Dependent Claim
23 words
A method as set forth in claim 33, wherein said third integration speed is a value between said first and second integration speeds.
Claim 39
Dependent Claim
69 words
A method as set forth in claim 33, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 40
Dependent Claim
32 words
A method as set forth in claim 36, further comprising a step of setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 41
Dependent Claim
37 words
A method as set forth in claim 37, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 42
Dependent Claim
69 words
A method as set forth in claim 33, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 43
Dependent Claim
32 words
A method as set forth in claim 39, further comprising a step of setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 44
Dependent Claim
37 words
A method as set forth in claim 40, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 45
Dependent Claim
38 words
A method as set forth in claim 33, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 46
Dependent Claim
53 words
A method as set forth in claim 33, further comprising the steps of: detecting a transition in said engine from the non-idling state to the idling state; and forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 47
Dependent Claim
32 words
A method as set forth in claim 43, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 48
Dependent Claim
29 words
A method as set forth in claim 43, wherein said transition detecting step detects only a transition from a small load state of said engine to the idling state.
Claim 49
Dependent Claim
69 words
A method as set forth in claim 45, wherein said transition detecting step comprises a step of determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 50
Dependent Claim
86 words
A method as set forth in claim 45, wherein said transition detecting step comprises the steps of: determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 51
Dependent Claim
41 words
A method as set forth in claim 33, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 52
Dependent Claim
51 words
A method as set forth in claim 48, wherein said self-oscillating term calculating step comprises the steps of: decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 53
Independent Claim
346 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 54
Independent Claim
346 words
A method of controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an idling state or in a non-idling state; measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the idling state; and adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 55
Dependent Claim
23 words
A method as set forth in claim 50, wherein said third integration speed is a value between said first and second integration speeds.
Claim 56
Dependent Claim
69 words
A method as set forth in claim 50, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 57
Dependent Claim
32 words
A method as set forth in claim 52, further comprising a step of setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 58
Dependent Claim
37 words
A method as set forth in claim 53, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 59
Dependent Claim
69 words
A method as set forth in claim 50, further comprising the steps of: determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 60
Dependent Claim
32 words
A method as set forth in claim 55, further comprising a step of setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 61
Dependent Claim
37 words
A method as set forth in claim 56, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 62
Dependent Claim
38 words
A method as set forth in claim 50, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 63
Dependent Claim
53 words
A method as set forth in claim 50, further comprising the steps of: detecting a transition in said engine from the non-idling state to the idling state; and forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 64
Dependent Claim
32 words
A method as set forth in claim 59, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 65
Dependent Claim
29 words
A method as set forth in claim 59, wherein said transition detecting step detects only a transition from a small load state of said engine to the idling state.
Claim 66
Dependent Claim
69 words
A method as set forth in claim 61, wherein said transition detecting step comprises a step of determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 67
Dependent Claim
86 words
A method as set forth in claim 61, wherein said transition detecting step comprises the steps of: determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and calculating a degree of determination that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 68
Dependent Claim
41 words
A method as set forth in claim 50, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting step adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 69
Dependent Claim
51 words
A method as set forth in claim 64, wherein said self-oscillating term calculating step comprises the steps of: decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 70
Dependent Claim
72 words
A method as set forth in claim 50, further comprising the steps of: gradually decreasing said O 2 storage term, when the output of said air-fuel ratio sensor is higher than the first level and said engine is in the non-idling state; and gradually increasing said O 2 storage term, when the output of said air-fuel ratio sensor is lower than the second level and said engine is in the non-idling state.
Claim 71
Independent Claim
236 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, when said engine is in the non-idling state.
Claim 72
Independent Claim
236 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, when said engine is in the non-idling state.
Claim 73
Dependent Claim
23 words
An apparatus as set forth in claim 67, wherein said third integration speed is a value between said first and second integration speeds.
Claim 74
Dependent Claim
70 words
An apparatus as set forth in claim 67, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and means for prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 75
Dependent Claim
31 words
An apparatus as set forth in claim 69, further comprising means for setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 76
Dependent Claim
37 words
An apparatus as set forth in claim 70, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 77
Dependent Claim
70 words
An apparatus as set forth in claim 67, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and means for prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 78
Dependent Claim
31 words
An apparatus as set forth in claim 72, further comprising means for setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 79
Dependent Claim
37 words
An apparatus as set forth in claim 73, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 80
Dependent Claim
38 words
An apparatus as set forth in claim 67, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 81
Dependent Claim
54 words
An apparatus as set forth in claim 67, further comprising: means for detecting a transition in said engine from the non-idling state to the idling state; and means for forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 82
Dependent Claim
32 words
An apparatus as set forth in claim 76, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 83
Dependent Claim
29 words
An apparatus as set forth in claim 76, wherein said transition detecting means detects only a transition from a small load state of said engine to the idling state.
Claim 84
Dependent Claim
68 words
An apparatus as set forth in claim 78, wherein said transition detecting means comprises means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 85
Dependent Claim
87 words
An apparatus as set forth in claim 78, wherein said transition detecting means comprises: means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and means for calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value, thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 86
Dependent Claim
40 words
An apparatus as set forth in claim 67, further comprising means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 87
Dependent Claim
52 words
An apparatus as set forth in claim 81, wherein said self-oscillating term calculating means comprises: means for decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and means for increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 88
Independent Claim
291 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; means for calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said fine-adjusting term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said fine-adjusting term, when said engine is in the non-idling state.
Claim 89
Independent Claim
291 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; means for calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said fine-adjusting term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said fine-adjusting term, when said engine is in the non-idling state.
Claim 90
Dependent Claim
23 words
An apparatus as set forth in claim 83, wherein said third integration speed is a value between said first and second integration speeds.
Claim 91
Dependent Claim
70 words
An apparatus as set forth in claim 84, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and means for prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 92
Dependent Claim
31 words
An apparatus as set forth in claim 85, further comprising means for setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 93
Dependent Claim
37 words
An apparatus as set forth in claim 86, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 94
Dependent Claim
70 words
An apparatus as set forth in claim 83, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and means for prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 95
Dependent Claim
31 words
An apparatus as set forth in claim 88, further comprising means for setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 96
Dependent Claim
37 words
An apparatus as set forth in claim 89, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 97
Dependent Claim
38 words
An apparatus as set forth in claim 83, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 98
Dependent Claim
54 words
An apparatus as set forth in claim 83, further comprising: means for detecting a transition in said engine from the non-idling state to the idling state; and means for forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 99
Dependent Claim
32 words
An apparatus as set forth in claim 92, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 100
Dependent Claim
29 words
An apparatus as set forth in claim 92, wherein said transition detecting step detects only a transition from a small load state of said engine to the idling state.
Claim 101
Dependent Claim
68 words
An apparatus as set forth in claim 94, wherein said transition detecting means comprises means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 102
Dependent Claim
87 words
An apparatus as set forth in claim 94, wherein said transition detecting means comprises: means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and means for calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 103
Dependent Claim
40 words
An apparatus as set forth in claim 83, further comprising means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 104
Dependent Claim
52 words
An apparatus as set forth in claim 97, wherein said self-oscillating term calculating means comprises: means for decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and means for increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 105
Independent Claim
312 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; means for calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said O 2 storage term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 106
Independent Claim
312 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; means for calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term and said O 2 storage term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 107
Dependent Claim
73 words
An apparatus as set forth in claim 99, further comprising: means for gradually decreasing said O 2 storage term, when the output of said air-fuel ratio sensor is higher than the first level and said engine is in the non-idling state; and means for gradually increasing said O 2 storage term, when the output of said air-fuel ratio sensor is lower than the second level and said engine is in the non-idling state.
Claim 108
Dependent Claim
23 words
An apparatus as set forth in claim 99, wherein said third integration speed is a value between said first and second integration speeds.
Claim 109
Dependent Claim
70 words
An apparatus as set forth in claim 99, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and means for prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 110
Dependent Claim
31 words
An apparatus as set forth in claim 102, further comprising means for setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 111
Dependent Claim
37 words
An apparatus as set forth in claim 103, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 112
Dependent Claim
70 words
An apparatus as set forth in claim 99, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and means for prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 113
Dependent Claim
31 words
An apparatus as set forth in claim 105, further comprising means for setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 114
Dependent Claim
37 words
An apparatus as set forth in claim 106, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 115
Dependent Claim
38 words
An apparatus as set forth in claim 99, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 116
Dependent Claim
54 words
An apparatus as set forth in claim 99, further comprising: means for detecting a transition in said engine from the non-idling state to the idling state; and means for forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 117
Dependent Claim
32 words
An apparatus as set forth in claim 109, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 118
Dependent Claim
29 words
An apparatus as set forth in claim 109, wherein said transition detecting means detects only a transition from a small load state of said engine to the idling state.
Claim 119
Dependent Claim
68 words
An apparatus as set forth in claim 111, wherein said transition detecting means comprises means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 120
Dependent Claim
87 words
An apparatus as set forth in claim 111, wherein said transition detecting means comprises: means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and means for calculating a degree of determinations that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 121
Dependent Claim
40 words
An apparatus as set forth in claim 99, further comprising means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 122
Dependent Claim
52 words
An apparatus as set forth in claim 114, wherein said self-oscillating term calculating means comprises: means for decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and means for increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 123
Independent Claim
365 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; means for calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; means for calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; means for calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 124
Independent Claim
365 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a three-way catalyst converter for removing pollutants in the exhaust gas of said engine, and an air-fuel ratio sensor, disposed downstream of or within said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether said engine is in an idling state or in a non-idling state; means for measuring a duration after the output of said air-fuel ratio sensor is inverted, when said engine is in the idling state; means for changing an idling coarse-adjusting term at a first integration speed in response to the output of said air-fuel ratio sensor, when said duration is smaller than a predetermined time; means for gradually changing said idling coarse-adjusting term at a second integration speed smaller than said first integration speed, in response to the output of said air-fuel ratio sensor, when said duration is not smaller than said predetermined time; means for gradually changing a non-idling coarse-adjusting term at a third integration speed in response to the output of said air-fuel ratio sensor, when said engine is in the non-idling state; means for calculating a fine-adjusting term having a positive value, when the output of said air-fuel ratio sensor is on the lean side; means for calculating a fine adjusting term having a negative value, when the output of said air-fuel ratio sensor is on the rich side; means for calculating an O 2 storage term having a negative value, when the output of said air-fuel ratio sensor is higher than a first level corresponding to a rich air-fuel ratio; means for calculating an O 2 storage term having a positive value, when the output of said air-fuel ratio sensor is lower than a second level corresponding to a lean air-fuel ratio; means for adjusting an actual air-fuel ratio in accordance with said idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the idling state; and means for adjusting the actual air-fuel ratio in accordance with said non-idling coarse-adjusting term, said fine-adjusting term and said O 2 storage term, when said engine is in the non-idling state.
Claim 125
Dependent Claim
23 words
An apparatus as set forth in claim 116, wherein said third integration speed is a value between said first and second integration speeds.
Claim 126
Dependent Claim
70 words
An apparatus as set forth in claim 116, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the idling state; and means for prohibiting the changing of said idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 127
Dependent Claim
31 words
An apparatus as set forth in claim 118, further comprising means for setting a predetermined value in said idling coarse-adjusting term, when the changing of said idling coarse-adjusting term is prohibited.
Claim 128
Dependent Claim
37 words
An apparatus as set forth in claim 119, wherein the predetermined value is an intermediate value between maximum and minimum values of said idling coarse-adjusting term immediately before the changing of said idling coarse-adjusting term is prohibited.
Claim 129
Dependent Claim
70 words
An apparatus as set forth in claim 116, further comprising: means for determining whether or not a repetition period of the output of said air-fuel ratio sensor is smaller than a predetermined period, when said engine is in the non-idling state; and means for prohibiting the changing of said non-idling coarse-adjusting term, when the repetition period of the output of said air-fuel ratio sensor is smaller than the predetermined period.
Claim 130
Dependent Claim
31 words
An apparatus as set forth in claim 121, further comprising means for setting a predetermined value in said non-idling coarse-adjusting term, when the changing of said non-idling coarse-adjusting term is prohibited.
Claim 131
Dependent Claim
37 words
An apparatus as set forth in claim 112, wherein the predetermined value is an intermediate value between maximum and minimum values of said non-idling coarse-adjusting term immediately before the changing of said non-idling coarse-adjusting term is prohibited.
Claim 132
Dependent Claim
38 words
An apparatus as set forth in claim 116, wherein said first integration speed of said idling coarse-adjusting term to the rich side is smaller than said first integration speed of said idling coarse-adjusting term to the lean side.
Claim 133
Dependent Claim
54 words
An apparatus as set forth in claim 111, further comprising: means for detecting a transition in said engine from the non-idling state to the idling state; and means for forcibly changing said idling coarse-adjusting term at said second integration speed in response to the output of said air-fuel ratio sensor for a predetermined period.
Claim 134
Dependent Claim
32 words
An apparatus as set forth in claim 125, said predetermined period is defined by a period from said transition to a timing when the output of said air-fuel ratio sensor is inverted.
Claim 135
Dependent Claim
29 words
An apparatus as set forth in claim 125, wherein said transition detecting means detects only a transition from a small load state of said engine to the idling state.
Claim 136
Dependent Claim
68 words
An apparatus as set forth in claim 127, wherein said transition detecting means comprises means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state, thereby determining that a small load state occurs in said engine when the intake air amount per one engine revolution is smaller than the predetermined value.
Claim 137
Dependent Claim
87 words
An apparatus as set forth in claim 127, wherein said transition detecting means comprises: means for determining whether or not an intake air amount per one engine revolution is smaller than a predetermined value, when said engine is in the non-idling state; and means for calculating a degree of determination that the intake air amount per one engine revolution is smaller than the predetermined value; thereby determining that a small load state occurs in said engine, when the degree of determination is larger than a predetermined value.
Claim 138
Dependent Claim
40 words
An apparatus as set forth in claim 116, further comprising means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, said air-fuel ratio adjusting means adjusting said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 139
Dependent Claim
52 words
An apparatus as set forth in claim 130, wherein said self-oscillating term calculating means comprises: means for decreasing said predetermined amplitude of said self-oscillating term when said engine is in the idling state; and means for increasing said predetermined period of said self-oscillating term when said engine is in the idling state.
Claim 140
Dependent Claim
73 words
An apparatus as set forth in claim 116, further comprising: means for gradually decreasing said O 2 storage term, when the output of said air-fuel ratio sensor is higher than the first level and said engine is in the non-idling state; and means for gradually increasing said O 2 storage term, when the output of said air-fuel ratio sensor is lower than the second level and said engine is in the non-idling state.
References Cited (Backward Citations)
US4173952A
Cited
JPS5281438A
Cited
US4173956A
Cited
JPS5623532A
Cited
JPS5623531A
Cited
JPS5623533A
Cited
JPS56126650A
Cited
JPS56126649A
Cited
JPS56126647A
Cited
JPS56126648A
Cited
JPS57135243A
Cited
JPS5848745A
Cited
US4840027A
Cited
JPS6453042A
Cited
JPS6466441A
Cited
JPH01121538A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-12-09 | 1995-06-10 | 1995-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-09 | 1999-06-10 | 1999-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-12-09 | 2003-06-10 | 2003-12-10 | $7700.00 | Window Closed / Lapsed |