US5022225A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio feedback control system including at least downstream-side air fuel ratio sensor
Assignee: Toyota Motor Corp
•
Filing: 1990-03-23
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Granted: 1991-06-11
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Expires: 2010-03-23
Abstract
Abstract In an air-fuel ratio feedback control system including at least one air-fuel ratio sensor downstream of a catalyst converter provided in an exhaust gas passage, an actual air-fuel ratio is controlled in accordance with the output of the downstream-side air-fuel ratio sensor. When at least one of the air-fuel ratio feedback control conditions for the downstream-side air-fuel ratio sensor is not satisfied the controlled air-fuel ratio is made an air-fuel ratio by an open loop control, while all the air-fuel ratio feedback control conditions for the downstream-side air-fuel ratio sensor are satisfied the controlled air-fuel ratio is made the stoichometric ratio (λ=1) in accordance with the output of the downstream-side air-fuel ratio sensor. For a period after all the air-fuel ratio feedback control conditions for the downstream-side air-fuel ratio sensor are satisfied, the control by the output of the downstream-side air-fuel ratio sensor is prohibited, but, the controlled air-fuel ratio is made the stoichiometric ratio (λ=1) by an open loop control or by the output of an upstream-side air-fuel ratio sensor.
Inventors
- 👤 Hiroshi Sawada
- 👤 Tatehito Ueda
- 👤 Kiyoshi Nakanishi
- 👤 Takayuki Demura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:14
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/04; F02D41/12; F02D41/123; F02D41/1477; F02D41/1481; F02D41/1486; F02D41/1488; F02D41/1401; F02D2041/1413; F02D2041/1418; F02D2200/00; F02D2200/02; F02D2200/021; F02D41/08; F02D41/1444; F02D41/1454
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
250 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pullutants in the exhaust gas thereof and a downstream-side air-fuel ratio sensor disposed downstream of said catalyst converter, for detecting concentration of a specific component in the exhaust gas, comprising the steps of: sensing air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor; determining whether or not all the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to an air-fuel ratio, when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to the stoichiometric air-fuel ratio while prohibiting control of said air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor for a period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and controlling the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor so that it is brought close to the stoichiometric air-fuel ratio after said period has passed, said period being determined by an addition of a transport delay period of the exhaust gas and a delay period due to the O 2 storage effect.
Claim 2
Independent Claim
250 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pullutants in the exhaust gas thereof and a downstream-side air-fuel ratio sensor disposed downstream of said catalyst converter, for detecting concentration of a specific component in the exhaust gas, comprising the steps of: sensing air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor; determining whether or not all the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to an air-fuel ratio, when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to the stoichiometric air-fuel ratio while prohibiting control of said air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor for a period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and controlling the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor so that it is brought close to the stoichiometric air-fuel ratio after said period has passed, said period being determined by an addition of a transport delay period of the exhaust gas and a delay period due to the O 2 storage effect.
Claim 3
Dependent Claim
105 words
A method as set forth in claim 1, further comprising the steps of: calculating a time period from a time when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied to a time when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; determining whether or not said time period is smaller than a definite period; and prohibiting the control of the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor when said time period is smaller than said definite period.
Claim 4
Dependent Claim
32 words
A method as set forth in claim 1, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a fuel cut-off state of said engine.
Claim 5
Dependent Claim
31 words
A method as set forth in claim 1, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a coolant temperature of said engine.
Claim 6
Dependent Claim
31 words
A method as set forth in claim 1, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of an idling state of said engine.
Claim 7
Dependent Claim
35 words
A method as set forth in claim 1, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of an activation state of said downstream- side air-fuel ratio sensor.
Claim 8
Dependent Claim
30 words
A method as set forth in claim 1, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a load of said engine.
Claim 9
Dependent Claim
16 words
A method as set forth in claim 1, wherein said period is a definite time period.
Claim 10
Dependent Claim
60 words
A method as set forth in claim 1, wherein said air-fuel ratio controlling step in accordance with the output of said downstream-side air-fuel ratio sensor comprises the steps of: calculating an air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 11
Independent Claim
258 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and a downstream-side air-fuel ratio sensor disposed downstream of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising: means for sensing air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor; means for determining whether or not all the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to an air-fuel ratio, when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; means for controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to the stoichiometric air-fuel ratio while prohibiting control of said air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor for a period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and means for controlling the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor so that it is brought close to the stoichiometric air-fuel ratio after said period has passed, said period being determined by an addition of a transport delay period of the exhaust gas and a delay period due to the O 2 storage effect.
Claim 12
Independent Claim
258 words
An apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and a downstream-side air-fuel ratio sensor disposed downstream of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising: means for sensing air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor; means for determining whether or not all the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; means for controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to an air-fuel ratio, when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; means for controlling the air-fuel ratio of said engine by an open loop control so that it is brought close to the stoichiometric air-fuel ratio while prohibiting control of said air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor for a period after all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied; and means for controlling the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor so that it is brought close to the stoichiometric air-fuel ratio after said period has passed, said period being determined by an addition of a transport delay period of the exhaust gas and a delay period due to the O 2 storage effect.
Claim 13
Dependent Claim
108 words
An apparatus as set forth in claim 10, further comprising: means for calculating a time period from a time when all of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor are satisfied to a time when at least one of the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor is not satisfied; means for determining whether or not said time period is smaller than a definite period; and means for prohibiting the control of the air-fuel ratio of said engine in accordance with the output of said downstream-side air-fuel ratio sensor when said time period is smaller than said definite period.
Claim 14
Dependent Claim
32 words
An apparatus as set forth in claim 10, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a fuel cut-off state of said engine.
Claim 15
Dependent Claim
31 words
An apparatus as set forth in claim 10, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a coolant temperature of said engine.
Claim 16
Dependent Claim
31 words
An apparatus as set forth in claim 10, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of an idling state of said engine.
Claim 17
Dependent Claim
34 words
An apparatus as set forth in claim 10, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of an activation state of said downstream-side air-fuel ratio sensor.
Claim 18
Dependent Claim
30 words
An apparatus as set forth in claim 10, wherein the air-fuel ratio feedback control conditions for said downstream-side air-fuel ratio sensor include a condition of a load of said engine.
Claim 19
Dependent Claim
16 words
An apparatus as set forth in claim 10, wherein said period is a definite time period.
Claim 20
Dependent Claim
61 words
An apparatus as set forth in claim 10, wherein said air-fuel ratio controlling means in accordance with the output of said downstream-side air-fuel ratio sensor comprises: means for calculating an air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
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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) | 1994-06-10 | 1994-12-10 | 1995-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-10 | 1998-12-10 | 1999-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-10 | 2002-12-10 | 2003-06-11 | $7700.00 | Window Closed / Lapsed |