US5475975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio control device for an engine
Assignee: Toyota Motor Corp
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Filing: 1994-09-14
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Granted: 1995-12-19
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Expires: 2014-09-14
Abstract
Abstract The air-fuel ratio control device according to the present invention controls the air-fuel ratio of the engine in accordance with the output of the air-fuel ratio sensor disposed on the exhaust gas passage upstream of the three-way reducing and oxidizing catalyst. Further, to compensate for the change in the output characteristics of the upstream air-fuel ratio sensor, the output of the upstream air-fuel ratio sensor is corrected in accordance with the output of another air-fuel ratio sensor disposed on the exhaust gas passage downstream of the catalyst. Since the response of the downstream air-fuel ratio sensor is delayed due to the O 2 storage capacity of the catalyst, the air-fuel ratio control device in the present invention predicts the future value, by a specified time, of the output of the downstream air-fuel ratio sensor based on the history of the change in the output of the upstream air-fuel ratio sensor and the present output of the downstream air-fuel ratio sensor. Since the output of the upstream air-fuel ratio sensor is corrected based on the predicted output of the downstream air-fuel ratio sensor, precise air-fuel ratio control can be achieved by eliminating the delay in the response of the downstream air-fuel ratio sensor caused by the O 2 storage capacity of the catalyst.
Inventors
- 👤 Masahiro Nasu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 05:47
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
184 words
An air-fuel ratio control device for an internal combustion engine having an exhaust gas passage, said engine comprising, a three-way reducing and oxidizing catalytic converter having an oxygen storage capacity and disposed on said exhaust passage, said air-fuel ratio control device comprising: an upstream air-fuel ratio sensor disposed on the exhaust gas passage upstream of said catalytic converter for detecting an air-fuel ratio of the exhaust gas upstream of said catalytic converter; a downstream air-fuel ratio sensor disposed on the exhaust passage downstream of said catalytic converter for detecting the air-fuel ratio of the exhaust gas downstream of said catalytic converter; a predicting means for predicting a value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter at a specified time after the present time, based on the output of said downstream air-fuel ratio sensor at the present time; and, an air-fuel ratio control means for controlling the air-fuel ratio of said engine based on said output of the upstream air-fuel ratio sensor and said predicted value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter.
Claim 2
Dependent Claim
184 words
An air-fuel ratio control device for an internal combustion engine having an exhaust gas passage, said engine comprising, a three-way reducing and oxidizing catalytic converter having an oxygen storage capacity and disposed on said exhaust passage, said air-fuel ratio control device comprising: an upstream air-fuel ratio sensor disposed on the exhaust gas passage upstream of said catalytic converter for detecting an air-fuel ratio of the exhaust gas upstream of said catalytic converter; a downstream air-fuel ratio sensor disposed on the exhaust passage downstream of said catalytic converter for detecting the air-fuel ratio of the exhaust gas downstream of said catalytic converter; a predicting means for predicting a value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter at a specified time after the present time, based on the output of said downstream air-fuel ratio sensor at the present time; and, an air-fuel ratio control means for controlling the air-fuel ratio of said engine based on said output of the upstream air-fuel ratio sensor and said predicted value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter.
Claim 3
Dependent Claim
64 words
A device according to claim 1, wherein said predicting means predicts said value of the air-fuel ratio at the specified time after the present time based on the output response of said upstream air-fuel ratio sensor during a period from a specified time before the present time to the present time, and the output of said downstream air-fuel ratio sensor at the present time.
Claim 4
Dependent Claim
75 words
A device according to claim 2, wherein said specified time at which value of the air-fuel ratio is predicted is equal to a delay time between the moment at which a change in the air-fuel ratio of the exhaust gas upstream of the catalytic converter occurs and the moment at which said change is detected by said downstream air-fuel ratio sensor said delay time being caused by said oxygen storage capacity of said catalytic converter.
Claim 5
Dependent Claim
65 words
A device according to claim 3, wherein said predicting means predicts said value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter by approximating the response of the air-fuel ratio of the exhaust gas downstream of the catalytic converter to the change of the air-fuel ratio of the exhaust gas upstream of the catalytic converter by a first order lag system.
Claim 6
Dependent Claim
75 words
A device according to claim 4, wherein said air-fuel ratio control means comprising, a correction means for correcting the output of said upstream air-fuel ratio sensor in accordance with a deviation of said predicted value of the air-fuel ratio of the exhaust gas downstream of said catalytic converter from the stoichiometric air-fuel ratio, and a means for controlling the air-fuel ratio of said engine based on said corrected output of said upstream air-fuel ratio sensor.
Claim 7
Dependent Claim
70 words
A device according to claim 5, wherein said upstream air-fuel ratio sensor is an A/F sensor which generates a continuous output signal corresponding to the air-fuel ratio of the exhaust gas, and said downstream air-fuel ratio sensor is an O 2 sensor which generates an output signal which changes in accordance with whether the air-fuel ratio of the exhaust gas is rich or lean compared with a stoichiometric air-fuel ratio.
Claim 8
Dependent Claim
177 words
An air-fuel ratio control device for an internal combustion engine having an exhaust gas passage, said engine comprising, a three-way reducing and oxidizing catalytic converter having an oxygen storage capacity and disposed on said exhaust passage, said air-fuel ratio control device comprising: an upstream air-fuel ratio sensor disposed on the exhaust gas passage upstream of said catalytic converter for detecting an air-fuel ratio of the exhaust gas upstream of said catalytic converter; a downstream air-fuel ratio sensor disposed on the exhaust passage downstream of said catalytic converter for detecting the air-fuel ratio of the exhaust gas downstream of said catalytic converter; a predicting means for predicting a value of the output of said downstream air-fuel ratio sensor at a specified time after the present time, based on the output of said downstream air-fuel ratio sensor at the present time; and, an air-fuel ratio control means for controlling the air-fuel ratio of said engine based on said output of the upstream air-fuel ratio sensor and said predicted future value of the output of the downstream air-fuel ratio sensor.
Claim 9
Dependent Claim
177 words
An air-fuel ratio control device for an internal combustion engine having an exhaust gas passage, said engine comprising, a three-way reducing and oxidizing catalytic converter having an oxygen storage capacity and disposed on said exhaust passage, said air-fuel ratio control device comprising: an upstream air-fuel ratio sensor disposed on the exhaust gas passage upstream of said catalytic converter for detecting an air-fuel ratio of the exhaust gas upstream of said catalytic converter; a downstream air-fuel ratio sensor disposed on the exhaust passage downstream of said catalytic converter for detecting the air-fuel ratio of the exhaust gas downstream of said catalytic converter; a predicting means for predicting a value of the output of said downstream air-fuel ratio sensor at a specified time after the present time, based on the output of said downstream air-fuel ratio sensor at the present time; and, an air-fuel ratio control means for controlling the air-fuel ratio of said engine based on said output of the upstream air-fuel ratio sensor and said predicted future value of the output of the downstream air-fuel ratio sensor.
Claim 10
Dependent Claim
59 words
A device according to claim 7, wherein said predicting means predicts said future value of the output of said downstream air-fuel ratio sensor based on the output response of said upstream air-fuel ratio sensor during a period from a specified time before the present time to the present time, and the present output of said downstream air-fuel ratio sensor.
Claim 11
Dependent Claim
78 words
A device according to claim 8, wherein said specified time at which the output of said downstream air-fuel ratio sensor is predicted is equal to a delay time between the moment at which a change in the air-fuel ratio of the exhaust gas upstream of the catalytic converter occurs and the moment at which said change is detected by said downstream air-fuel ratio sensor, said delay time being caused by said oxygen storage capacity of said catalytic converter.
Claim 12
Dependent Claim
54 words
A device according to claim 9, wherein said predicting means predicts said future value of the output of said downstream air-fuel ratio sensor by approximating the response of the output of the downstream air-fuel ratio sensor to the change of the output of said upstream air-fuel ratio sensor by a first order lag system.
Claim 13
Dependent Claim
85 words
A device according to claim 10, wherein said air-fuel ratio control means comprises, a correction means for correcting the output of said upstream air-fuel ratio sensor in accordance with a deviation of said predicted future value of the output of said downstream air-fuel ratio sensor from the value of the output of said downstream air-fuel ratio sensor corresponding to a stoichiometric air-fuel ratio, and a means for controlling the air-fuel ratio of said engine based on said corrected output of said upstream air-fuel ratio sensor.
Claim 14
Dependent Claim
70 words
A device according to claim 11, wherein said upstream air-fuel ratio sensor is an A/F sensor which generates a continuous output signal corresponding to the air-fuel ratio of the exhaust gas, and said downstream air-fuel ratio sensor is an O 2 sensor which generates an output signal which changes in accordance with whether the air-fuel ratio of the exhaust gas is rich or lean compared with a stoichiometric air-fuel ratio.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-12-18 | 1999-06-19 | 1999-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-18 | 2003-06-19 | 2003-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-18 | 2007-06-19 | 2007-12-19 | $7700.00 | Window Closed / Lapsed |