US5092123A
Expired / Lapsed
US
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Air-fuel ratio feedback control system having air-fuel ratio sensors upstream and downstream of three-way catalyst converter
Assignee: Toyota Motor Corp
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Filing: 1991-06-20
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Granted: 1992-03-03
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Expires: 2011-06-20
Abstract
Abstract In an air-fuel ratio feedback control system including air-fuel ratio sensors upstream and downstream of a three-way catalyst converter, the cold-condition compensating term is calculated in accordance with the upstream air-fuel ratio sensor disposed upstream of the catalyst converter, and the O 2 storage term is calculated in accordance with the downstream air-fuel ratio sensor disposed downstream thereof.
Inventors
- 👤 Mitsuhiro Nada
- 👤 Hiroshi Sawada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:42
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1482; F02D41/1439; F02D41/1441; F02D41/1486; F02D41/1487
Claims Analysis
Total Claims: 26
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, a first air-fuel ratio sensor, disposed upstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, and a second air-fuel ratio sensor, disposed downstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether or not said first air-fuel ratio sensor is active; determining whether or not said second air-fuel ratio sensor is active; gradually changing a cold-condition compensating term in accordance with the output of said first air-fuel ratio sensor when it is active; gradually changing a coarse-adjusting term in accordance with the output of said second air-fuel ratio sensor when it is active; gradually changing an O 2 storage adjusting term corresponding to an O 2 storage amount in said three-way catalyst converter in accordance with the output of said second air-fuel ratio sensor when it is active; adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said O 2 storage term when said second air-fuel-ratio sensor is active; adjusting said actual air-fuel ratio in accordance with said cold-condition compensating term when said first air-fuel ratio sensor is active, and said second air-fuel ratio sensor is not active.
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, a first air-fuel ratio sensor, disposed upstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, and a second air-fuel ratio sensor, disposed downstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising the steps of: determining whether or not said first air-fuel ratio sensor is active; determining whether or not said second air-fuel ratio sensor is active; gradually changing a cold-condition compensating term in accordance with the output of said first air-fuel ratio sensor when it is active; gradually changing a coarse-adjusting term in accordance with the output of said second air-fuel ratio sensor when it is active; gradually changing an O 2 storage adjusting term corresponding to an O 2 storage amount in said three-way catalyst converter in accordance with the output of said second air-fuel ratio sensor when it is active; adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said O 2 storage term when said second air-fuel-ratio sensor is active; adjusting said actual air-fuel ratio in accordance with said cold-condition compensating term when said first air-fuel ratio sensor is active, and said second air-fuel ratio sensor is not active.
Claim 3
Dependent Claim
104 words
A method as set forth claim 1, further comprising the steps of: determining whether or not the output of said second air-fuel ratio sensor is changed from a rich side to a lean side; greatly increasing said coarse-adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said second air-fuel ratio sensor is changed from the lean side to the rich side; greatly reducing said coarse-adjusting term when the output of said second air-fuel ratio sensor is changed from the lean side to the rich side.
Claim 4
Dependent Claim
110 words
A method as set forth claim 1, further comprising the steps of: determining whether or not the output of said second air-fuel ratio sensor is changed from a rich side to a lean side; greatly increasing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said second air-fuel ratio sensor is changed from the lean side to the rich side; greatly reducing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the lean side to the rich side.
Claim 5
Dependent Claim
106 words
A method as set forth claim 1, further comprising the steps of: determining whether or not the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; greatly increasing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said first air-fuel ratio sensor is changed from the lean side to the rich side; greatly reducing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed form the lean side to the rich side.
Claim 6
Dependent Claim
47 words
A method as set forth claim 1, further comprising the steps of: determining whether or not the warming-up of said catalyst converter is completed; increasing said gradual change of a speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 7
Dependent Claim
49 words
A method as set forth claim 3, further comprising the steps of: determining whether or not the warming up of said catalyst converter is completed; increasing the great change of an amount of said O 2 storage adjusting term when the warming up of said catalyst converter is completed.
Claim 8
Dependent Claim
88 words
A method as set forth claim 5, further comprising the steps of: determining whether or not the output of said second air-fuel ratio sensor is in a semi-stoichiometric air-fuel ratio region between a first threshold value which is smaller than a value corresponding to the stoichiometric air-fuel ratio and a second threshold value which is larger than a value corresponding to the stoichiometric air-fuel ratio; eliminating said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is in said semi-stoichiometric air-fuel ratio region.
Claim 9
Dependent Claim
71 words
A method as set forth claim 5, wherein said gradually changing speeds satisfy a following relationship; α1>α3>α2 where α= gradual change of a speed of said cold-condition compensating term α2=gradual change of speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is not completed. α3=gradual change of a speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 10
Dependent Claim
267 words
A method as set forth claim 3, further comprising the steps of: determining whether or not output of said first air-fuel ratio sensor is changed from the rich side to the lean side; greatly increasing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said first air-fuel ratio sensor is changed from the lean side to the rich side; greatly reducing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; greatly increasing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; greatly reducing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; wherein said greatly changed values satisfy a following relationship; AFccrop3>AFfrp>AFccrop2 where AFfr=great change of a value of said cold-condition compensating term AFccrop2=great change of a value of said O 2 storage adjusting term when the warming-up of said catalyst converter is not completed. AFccrop3=great change of a value of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 11
Dependent Claim
37 words
A method as set forth claim 1, further comprising a step of generating a self-oscillating term having a predetermined amplitude and a predetermined period, to thereby adjust said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 12
Dependent Claim
55 words
A method as set forth claim 10, further comprising the steps of: determining whether or not said engine is in an idling sate; lowering said predetermined amplitude of said self-oscillating term when said engine is in said idling state; increasing said predetermined period of said self-oscillating term when said engine is in said idling state.
Claim 13
Dependent Claim
41 words
A method as set forth claim 5, wherein said step of determining whether or not the warming-up of said catalyst converter is completed comprises a step of first determining whether or not said O 2 storage adjusting term has reached "0".
Claim 14
Independent Claim
237 words
An apparatus 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, a first air-fuel ratio sensor, disposed upstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, and a second air-fuel ratio sensor, disposed downstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether or not said first air-fuel ratio sensor is active; means for determining whether or not said second air-fuel ratio sensor is active; means for gradually changing a cold-condition compensating term in accordance with the output of said first air-fuel ratio sensor when it is active; means for gradually changing a coarse-adjusting term in accordance with the output of said second air-fuel ratio sensor when it is active; means for gradually changing an O 2 storage adjusting term corresponding to an O 2 storage amount in said three-way catalyst converter in accordance with the output of said second air-fuel ratio sensor when it is active; means for adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said O 2 storage term when said second air-fuel ratio sensor is active; means for adjusting said actual air-fuel ratio in accordance with said cold-condition compensating term when said first air-fuel ratio sensor is active, and said second air-fuel ratio sensor is not active.
Claim 15
Independent Claim
237 words
An apparatus 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, a first air-fuel ratio sensor, disposed upstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, and a second air-fuel ratio sensor, disposed downstream of said three-way catalyst converter, for detecting a specific component in the exhaust gas, comprising: means for determining whether or not said first air-fuel ratio sensor is active; means for determining whether or not said second air-fuel ratio sensor is active; means for gradually changing a cold-condition compensating term in accordance with the output of said first air-fuel ratio sensor when it is active; means for gradually changing a coarse-adjusting term in accordance with the output of said second air-fuel ratio sensor when it is active; means for gradually changing an O 2 storage adjusting term corresponding to an O 2 storage amount in said three-way catalyst converter in accordance with the output of said second air-fuel ratio sensor when it is active; means for adjusting an actual air-fuel ratio in accordance with said coarse-adjusting term and said O 2 storage term when said second air-fuel ratio sensor is active; means for adjusting said actual air-fuel ratio in accordance with said cold-condition compensating term when said first air-fuel ratio sensor is active, and said second air-fuel ratio sensor is not active.
Claim 16
Dependent Claim
109 words
An apparatus as set forth claim 13, further comprising: means for determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly increasing said coarse-adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said second air-fuel ratio sensor is changed from the lean side to the rich side; means for greatly reducing said coarse-adjusting term when the output of said second air-fuel ratio sensor is changed from he lean side to the rich side.
Claim 17
Dependent Claim
115 words
An apparatus as set forth claim 13, further comprising: means for determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly increasing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said second air-fuel ratio sensor is changed from the lean side to the rich side; means for greatly reducing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the lean side to the rich side.
Claim 18
Dependent Claim
111 words
An apparatus as set forth claim 13, further comprising: means for determining whether or not the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly increasing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said first air-fuel ratio sensor is changed from the lean side to the rich side; means for greatly reducing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the lean side to the rich side.
Claim 19
Dependent Claim
48 words
An apparatus as set forth claim 13, further comprising: means for determining whether or not the warming-up of said catalyst converter is completed; means for increasing said gradual change of a speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 20
Dependent Claim
48 words
An apparatus as set forth claim 15, further comprising: means for determining whether or not the warming-up of said catalyst converter is completed; means for increasing the great change in an amount of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 21
Dependent Claim
89 words
An apparatus as set forth claim 17, further comprising: means for determining whether or not the output of said second air-fuel ratio sensor is in a semi-stoichiometric air-fuel ratio region between a first threshold value which is smaller than a value corresponding to the stoichiometric air-fuel ratio and a second threshold value which is larger than a value corresponding to the stoichiometric air-fuel ratio; means for eliminating said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is in said semi-stoichiometric air-fuel ratio region.
Claim 22
Dependent Claim
71 words
An apparatus as set forth claim 17, wherein said gradually changing speeds satisfy a following relationship; α1>α3>α2 where α1=gradual change of a speed of said cold-condition compensating term α2=gradual change of a speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is not completed. α3=gradual change of a speed of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 23
Dependent Claim
280 words
An apparatus as set forth claim 13, further comprising: means for determining whether or not the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly increasing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said first air-fuel ratio sensor is changed from the lean side to the rich side; means for greatly reducing said cold-condition compensating term when the output of said first air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly increasing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for determining whether or not the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; means for greatly reducing said O 2 storage adjusting term when the output of said second air-fuel ratio sensor is changed from the rich side to the lean side; wherein said greatly changed value satisfy following relationship; AFccrop3>AFfrp>AFccrop2 where Affr=great change of a value of said cold-condition compensating term AFccrop2=great change of a value of said O 2 storage adjusting term when the warming-up of said catalyst converter is not completed. AFccrop3=great change of a value of said O 2 storage adjusting term when the warming-up of said catalyst converter is completed.
Claim 24
Dependent Claim
36 words
An apparatus as set forth claim 13, further comprising means for generating a self-oscillating term having a predetermined amplitude and a predetermined period, to thereby adjust said actual air-fuel ratio in accordance with said self-oscillating term.
Claim 25
Dependent Claim
58 words
An apparatus as set forth claim 22, further comprising: means for determining whether or not said engine is in an idling state; means for lowering said predetermined amplitude of said self-oscillating term when said engine is in said idling state; means for increasing said predetermined period of said self-oscillating term when said engine is in said idling state.
Claim 26
Dependent Claim
40 words
An apparatus as set forth claim 17, wherein said means of determining whether or not the warming-up of said catalyst converter is completed comprises means for first determining whether or not said O 2 storage adjusting term has reached "0".
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