US5440877A
Expired / Lapsed
US
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Air-fuel ratio controller for an internal combustion engine
Assignee: Mitsubishi Motors Corp
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Filing: 1994-09-26
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Granted: 1995-08-15
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Expires: 2014-09-26
Abstract
Abstract An alr-fuel ratio controller for-an internal-combustion engine is provided with front and rear O 2 sensors respectively installed in the exhaust system on the upstream and downstream sides of an exhaust gas purifier. The controller corrects the air-fuel ratio in accordance with the result of the comparison between a detected value of the front O 2 sensor and a first reference value, to thereby control the alr-fuel ratio to a desired value, and also corrects a value of a parameter related preferably to at least one of a correction amount or a correcting timing for the air-fuel ratio correction, e.g., the first reference value, in accordance with the deviation between a detected value of the rear O 2 sensor and a second reference value. When the deviation is large in magnitude, the parameter value is corrected at a larger correction degree than that used when the deviation magnitude is small, to thereby nonlinearly correct the parameter value in accordance with the magnitude of the deviation, whereby optimized correction of the parameter value is achieved so as to prevent the degeneration of the exhaust gas performance caused by the deterioration of the front and rear O 2 sensors or catalyst concerned.
Inventors
- 👤 Hitoshi Kamura
- 👤 Kazutoshi Noma
- 👤 Atsuyoshi Kojima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:08
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1444; F02D41/1454; F02D41/1439; F02D41/1441
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
202 words
An air-fuel ratio controller for an internal-combustion engine, comprising: an upstream-side oxygen sensor, installed in an exhaust system of the internal-combustion engine on an upstream side of an exhaust gas purifier, for detecting a first oxygen concentration in exhaust gas; a downstream-side oxygen sensor, installed in the exhaust system on a downstream side of or inside the exhaust gas purifier, for detecting a second oxygen concentration in exhaust gas; air-fuel ratio control means for correcting an air-fuel ratio of an air-fuel mixture supplied to the internal-combustion engine in accordance with a result of comparison between the first oxygen concentration value detected by said upstream-side oxygen sensor and a first reference value, to thereby control the air-fuel ratio to a desired value; and parameter value correcting means for correcting a value of a parameter, related to operation of said air-fuel ratio control means, in accordance with a difference between the second oxygen concentration value detected by said downstream-side oxygen sensor and a second reference value, said parameter value correcting means correcting the value of the parameter at a correction degree that changes according to a magnitude of the difference between the detected value of the second oxygen concentration and the second reference value.
Claim 2
Dependent Claim
202 words
An air-fuel ratio controller for an internal-combustion engine, comprising: an upstream-side oxygen sensor, installed in an exhaust system of the internal-combustion engine on an upstream side of an exhaust gas purifier, for detecting a first oxygen concentration in exhaust gas; a downstream-side oxygen sensor, installed in the exhaust system on a downstream side of or inside the exhaust gas purifier, for detecting a second oxygen concentration in exhaust gas; air-fuel ratio control means for correcting an air-fuel ratio of an air-fuel mixture supplied to the internal-combustion engine in accordance with a result of comparison between the first oxygen concentration value detected by said upstream-side oxygen sensor and a first reference value, to thereby control the air-fuel ratio to a desired value; and parameter value correcting means for correcting a value of a parameter, related to operation of said air-fuel ratio control means, in accordance with a difference between the second oxygen concentration value detected by said downstream-side oxygen sensor and a second reference value, said parameter value correcting means correcting the value of the parameter at a correction degree that changes according to a magnitude of the difference between the detected value of the second oxygen concentration and the second reference value.
Claim 3
Dependent Claim
26 words
The air-fuel ratio controller according to claim 1, wherein the parameter is related to the air-fuel ratio correction carried out by said air-fuel ratio control means.
Claim 4
Dependent Claim
31 words
The air-fuel ratio controller according to claim 2, wherein the parameter is related to at least one of a correction amount and a correction implementing timing in the air-fuel ratio correction.
Claim 5
Dependent Claim
36 words
The air-fuel ratio controller according to claim 1, wherein, when the difference is large, said parameter value correcting means corrects the parameter value at a larger correction degree than that used when the difference is small.
Claim 6
Dependent Claim
24 words
The air-fuel ratio controller according to claim 1, wherein said parameter value correcting means corrects the first reference value which serves as the parameter.
Claim 7
Dependent Claim
77 words
The air-fuel ratio controller according to claim 1, wherein said air-fuel ratio control means executes integral correction control for the air-fuel ratio control by using a correction factor which includes an integral correction term, and corrects a value of the integral correction term in accordance with the result of the comparison between the first oxygen concentration value and the first reference value, said parameter value correcting means correcting the integral correction term which functions as the parameter.
Claim 8
Dependent Claim
77 words
The air-fuel ratio controller according to claim 1, wherein said air-fuel ratio control means executes proportional correction control for the air-fuel ratio control by using a correction factor, which includes a proportional correction term, and corrects a value of the proportional correction term in accordance with the result of the comparison between the first oxygen concentration value and the first reference value, said parameter value correcting means correcting the proportional correction term which serves as the parameter.
Claim 9
Dependent Claim
61 words
The air-fuel ratio controller according to claim 1, wherein said air-fuel ratio control means corrects the air-fuel ratio at the moment when a desired delay time has elapsed since the first oxygen concentration value, which is detected by said upstream-side oxygen sensor, crossed the first reference value, said parameter value correcting means correcting the delay time which functions as the parameter.
Claim 10
Dependent Claim
36 words
The air-fuel ratio controller according to claim 1, wherein, when a magnitude of the difference is greater than a predetermined magnitude, said parameter value correcting means corrects the parameter value by a limited amount of correction.
Claim 11
Dependent Claim
36 words
The air-fuel ratio controller according to claim 1, wherein, when a magnitude of the difference is smaller than a predetermined magnitude, said parameter value correcting means does not effect any substantial correction to the parameter value.
Claim 12
Dependent Claim
48 words
The air-fuel ratio controller according to claim 1, wherein, said parameter value correcting means smooths a value of the second oxygen concentration detected by said downstream-side oxygen sensor, and corrects the parameter value in accordance with the difference between the smoothed value obtained and the second reference value.
Claim 13
Independent Claim
198 words
A method for controlling an air-fuel ratio in an internal-combustion engine, comprising the steps of: (a) detecting a first oxygen concentration in exhaust gas by an upstream-side oxygen sensor, installed in an exhaust system of the internal-combustion engine on an upstream side of an exhaust gas purifier; (b) detecting a second oxygen concentration in exhaust gas by a downstream-side oxygen sensor, installed in the exhaust system on a downstream side of or inside the exhaust gas purifier; (c) correcting the air-fuel ratio of an air-fuel mixture supplied to the internal-combustion engine in accordance with a result of comparison between the first oxygen concentration value detected by said upstream-side oxygen sensor and a first reference value, to thereby control the air-fuel ratio to a desired value; and (d) correcting a value of a parameter, related to operation of said step (c), in accordance with a difference between the second oxygen concentration value detected by said downstream-side oxygen sensor and a second reference value, so that the value of the parameter is corrected at a correction degree that changes according to a magnitude of the difference between the detected value of the second oxygen concentration and the second reference value.
Claim 14
Independent Claim
198 words
A method for controlling an air-fuel ratio in an internal-combustion engine, comprising the steps of: (a) detecting a first oxygen concentration in exhaust gas by an upstream-side oxygen sensor, installed in an exhaust system of the internal-combustion engine on an upstream side of an exhaust gas purifier; (b) detecting a second oxygen concentration in exhaust gas by a downstream-side oxygen sensor, installed in the exhaust system on a downstream side of or inside the exhaust gas purifier; (c) correcting the air-fuel ratio of an air-fuel mixture supplied to the internal-combustion engine in accordance with a result of comparison between the first oxygen concentration value detected by said upstream-side oxygen sensor and a first reference value, to thereby control the air-fuel ratio to a desired value; and (d) correcting a value of a parameter, related to operation of said step (c), in accordance with a difference between the second oxygen concentration value detected by said downstream-side oxygen sensor and a second reference value, so that the value of the parameter is corrected at a correction degree that changes according to a magnitude of the difference between the detected value of the second oxygen concentration and the second reference value.
Claim 15
Dependent Claim
27 words
The method for controlling an air-fuel ratio according to claim 12, wherein the parameter is related to the air-fuel ratio correction carried out at said step (c).
Claim 16
Dependent Claim
34 words
The method for controlling an air-fuel ratio according to claim 13, wherein the parameter is related to at least one of a correction amount and a correction implementing timing in the airfuel ratio correction.
Claim 17
Dependent Claim
39 words
The method for controlling an air-fuel ratio according to claim 12, wherein, when the difference is large, the parameter value is corrected at said step (d) at a larger correction degree than that used when the difference is small.
Claim 18
Dependent Claim
27 words
The method for controlling an air-fuel ratio according to claim 12, wherein the first reference value which serves as the parameter is corrected at said step (d).
Claim 19
Dependent Claim
85 words
The method for controlling an air-fuel ratio according to claim 12, wherein integral correction control is executed at said step (c) for the air-fuel ratio control by using a correction factor which includes an integral correction term, a value of the integral correction term is corrected at said step (c) in accordance with the result of the comparison between the first oxygen concentration value and the first reference value, and the integral correction term which functions as the parameter is corrected at said step (d).
Claim 20
Dependent Claim
86 words
The method for controlling an air-fuel ratio according to claim 12, wherein proportional correction control is executed at said step (c) for the air-fuel ratio control by using a correction factor, which includes a proportional correction term, a value of the proportional correction term is corrected at said step (c) in accordance with the result of the comparison between the first oxygen concentration a value and the first reference value, and the proportional correction term which serves as the parameter is corrected at said step (d).
Claim 21
Dependent Claim
65 words
The method for controlling an air-fuel ratio according to claim 12, wherein the air-fuel ratio is corrected at said step (c) at the moment when a desired delay time has elapsed since the first oxygen concentration value, which is detected by said upstream-side oxygen sensor, crossed the first reference value, and the delay time which functions as the parameter is corrected at said step (d).
Claim 22
Dependent Claim
39 words
The method for controlling an air-fuel ratio according to claim 12, wherein, when a magnitude of the difference is greater than a predetermined magnitude, the parameter value is corrected at said step (d) by a limited amount of correction.
Claim 23
Dependent Claim
38 words
The method for controlling an air-fuel ratio according to claim 12, wherein, when a magnitude of the difference is smaller than a predetermined magnitude, substantial correction to the parameter value fails to be affected at said step (d).
Claim 24
Dependent Claim
56 words
The method for controlling an air-fuel ratio according to claim 12, wherein a value of the second oxygen concentration detected by said downstream-side oxygen sensor is smoothed at said step (3), and the parameter value is corrected at said step (d) in accordance with the difference between the smoothed value obtained and the second reference value.
References Cited (Backward Citations)
US3827237A
Cited
US4594984A
Cited
US4580539A
Cited
US4912926A
Cited
US4870938A
Cited
US5095878A
Cited
US5099817A
Cited
US5154055A
Cited
US5220788A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-14 | 1999-02-13 | 1999-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-14 | 2003-02-13 | 2003-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-14 | 2007-02-13 | 2007-08-15 | $7700.00 | Window Closed / Lapsed |