EP0553570A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method for detecting and controlling air-fuel ratio in internal combustion engines
Assignee: Honda Motor Co Ltd
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Filing: 1992-12-29
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Granted: —
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Expires: 2012-12-29
Abstract
Abstract A method for detecting and controlling the air-fuel ratio of a multicylinder internal combustion engine (10) through an output of a single air-fuel ratio sensor (40) installed at a confluence point of the exhaust system (24) of the engine. The detection response delay is assumed to be a first-order lag and a state variable model is established. Further, the air-fuel ratio at the confluence point is assumed to be a sum of the products of the past firing histories of the each cylinder of the engine and a second state variable model is established. An observer is then designed to observe the internal state of the second model and the air-fuel ratio at the individual cylinders are estimated from the output of the observer. The deadbeat control is carried out by calculating a ratio between the estimated air-fuel ratio and a target air-fuel ratio. The calculated ratio is multiplied by a correction value at a preceding control cycle earlier by a number corresponding to the number of the engine cylinders.
Inventors
- 👤 Yusuke K.K. Honda Gijyutsu Kenkyusho Hasegawa
- 👤 Eisuke K.K. Honda Gijyutsu Kenkyusho Kimura
- 👤 Shusuke K.K. Honda Gijyutsu Kenkyusho Akazaki
- 👤 Isao K.K. Honda Gijyutsu Kenkyusho Komoriya
- 👤 Toshiaki K.K. Honda Gijyutsu Kenkyusho Hirota
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 01:35
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1481; F02D41/1401; F02D41/1402; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D41/2474; F02D41/2477; F02D2041/1409; F02D2041/1413; F02D2041/1415; F02D2041/1416; F02D2041/1417; F02D2041/1418; F02D2041/1431; F02D2041/1433; F02D2041/1434; F02D41/1444; F02D41/1454; F02D41/1456
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
99 words
A method for detecting the air-fuel ratio of a mixture supplied to an internal combustion engine through an output of an air-fuel ratio sensor, comprising: deeming a detection response lag of the sensor as a first-order lag to establish a state variable model; obtaining a state equation describing the behavior of the state variable model; discretizing the state equation for period delta T to obtain a transfer function; and obtaining an inverse transfer function of the transfer function and multiplying it to the output of the sensor to estimate the air-fuel ratio of the mixture supplied to the engine.
Claim 2
Dependent Claim
17 words
A method according to claim 1, wherein the period delta T is varied with the engine speed.
Claim 3
Dependent Claim
21 words
A method according to claim 1 or 2, wherein a coefficient of the transfer function is varied with the engine speed.
Claim 4
Independent Claim
35 words
A system according to any preceding claim, wherein the engine is a multicylinder engine and the air-fuel ratio sensor is installed at or downstream of a confluence point of an exhaust system of the engine.
Claim 5
Independent Claim
135 words
A method for detecting the air-fuel ratio of a mixture supplied to each cylinder of a multicylinder internal combustion engine through an output of an air-fuel ratio sensor installed at or downstream of a confluence point of an exhaust system of the engine, comprising: assuming the air-fuel ratio at or downstream of the confluence point as an average value made up of a sum of the products of the past firing histories of the each cylinder weighted by a predetermined value, to establish a state variable model describing the behavior of the exhaust system; obtaining a state equation having internal state variables on the air-fuel ratio at each cylinder; designing an observer to observe the internal state and obtaining its output; and estimating the air-fuel ratio at each cylinder from the output of the observer.
Claim 6
Independent Claim
158 words
A method for detecting the air-fuel ratio of a mixture supplied to each cylinder of a multicylinder internal combustion engine through an output of an air-fuel ratio sensor installed at or downstream of a confluence point of an exhaust system of the engine and controlling to a target value, comprising: assuming the air-fuel ratio at or downstream of the confluence point as an average value made up of a sum of the products of the past firing histories of the each cylinder weighted by a predetermined value, to establish a state variable model describing the behavior of the exhaust system; obtaining a state equation having internal state variables on the air-fuel ratio at each cylinder; designing an observer to observe the internal state and obtaining its output; estimating the air-fuel ratio at each cylinder from the output of the observer; and controlling the air-fuel ratio at each cylinder to the target value based on the estimated air-fuel ratio.
Claim 7
Dependent Claim
24 words
A system according to claim 5 or 6, wherein the predetermined value to be weighted is varied with the operating condition of the engine.
Claim 8
Independent Claim
194 words
A method for detecting the air-fuel ratio of a mixture supplied to each cylinder of a multicylinder internal combustion engine through an output of an air-fuel ratio sensor installed at or downstream of a confluence point of an exhaust system of the engine and controlling in discrete-time series the air-fuel ratio to a target value, comprising; assuming the air-fuel ratio at or downstream of the confluence point as an average value made up of a sum of the products of the past firing histories of the each cylinder weighted by a predetermined value, to establish a state variable model describing the behavior of the exhaust system; obtaining a state equation having internal state variables on the air-fuel ratio at each cylinder; designing an observer to observe the internal state and obtaining its output; estimating the air-fuel ratio at the each cylinder from the output of the observer; and calculating a ratio between the estimated air-fuel ratio and a target air-fuel ratio and determining a current correction value by multiplying the calculated ratio by a preceding correction value such that the air-fuel ratio at each cylinder converges on the target value with a deadbeat response.
Claim 9
Independent Claim
68 words
A method for controlling the air-fuel ratio of a multicylinder internal combustion engine, comprising: determining the air-fuel ratio at each cylinder of the engine; calculating a ratio between the determined ratio and a target ratio; and determining a current correction value by multiplying the calculated ratio by a preceding correction value such that the air-fuel ratio at each cylinder converges on the target value with a deadbeat response.
Claim 10
Dependent Claim
35 words
A method according to claim 8 or 9, wherein the preceding correction value is the value at a preceding control cycle earlier by the number corresponding to a multiple of the cylinder of the engine.
Claim 11
Dependent Claim
24 words
A method according to claim 10, wherein the multiple is a number at least greater than a triple of the cylinders of the engine.
References Cited (Backward Citations)
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