US4964272A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio feedback control system including at least downstreamside air-fuel ratio sensor
Assignee: Toyota Motor Corp
•
Filing: 1988-07-18
•
Granted: 1990-10-23
•
Expires: 2008-07-18
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 the engine is transferred from an open loop control state such as a fuel cut-off state or an OTP incremental state to an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by the downstream-side air-fuel ratio sensor, the speed of changing an air-fuel ratio correction amount in accordance with the output of the downstream-side air-fuel ratio sensor is at a conventional speed before the switching of the output of the downstream-side air-fuel ratio sensor, but thereafter (only immediately after the switching of the output of the downstream-side air-fuel ratio sensor or for a predetermined time period), this speed is increased.
Inventors
- 👤 Nobuaki Kayanuma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:04
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/1477; F02D41/1481; F02D41/1486; F02D41/1488
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
249 words
A method for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said upstream-side and downstream-side air-fuel ratio sensors; calculating an air-fuel ratio correction amount in accordance with outputs of said upstream-side and downstream-side air-fuel ratio sensors when said engine is in said air-fuel ratio feedback control state; determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs at an output of said downstream-side air-fuel ratio sensor; changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 2
Independent Claim
249 words
A method for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising the steps of: determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said upstream-side and downstream-side air-fuel ratio sensors; calculating an air-fuel ratio correction amount in accordance with outputs of said upstream-side and downstream-side air-fuel ratio sensors when said engine is in said air-fuel ratio feedback control state; determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs at an output of said downstream-side air-fuel ratio sensor; changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 3
Dependent Claim
40 words
A method as set forth in claim 1, wherein said open loop control state is a lean air-fuel ratio driving state, said speed increasing step increasing the speed of change of said air-fuel ratio correction amount to the lean side.
Claim 4
Dependent Claim
40 words
A method as set forth in claim 1, wherein said open loop control state is a rich air-fuel ratio driving state, said speed increasing step increasing the speed of change of said air-fuel ratio correction amount to the rich side.
Claim 5
Dependent Claim
51 words
A method as set forth in claim 1, wherein said speed increasing step increases the speed of change of said air-fuel ratio correction amount only immediately after a first occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 6
Dependent Claim
56 words
A method as set forth in claim 1, wherein said speed increasing step increases the speed of change of said air-fuel ratio correction amount from a first occurrence of said switching to a second occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 7
Dependent Claim
90 words
A method as set forth in claim 1, wherein said air-fuel ratio correction amount calculating step comprises the steps of: calculating a first air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor; calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts, said speed increasing step increasing the speed of change of said second air-fuel ratio correction amount.
Claim 8
Dependent Claim
78 words
A method as set forth in claim 1, wherein said air-fuel ratio correction amount calculating step comprises the steps of: calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor and said air-fuel ratio feedback control parameter, said speed increasing step increasing the speed of change of said air-fuel ratio feedback control parameter.
Claim 9
Dependent Claim
85 words
A method as set forth in claim 7, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said air-fuel ratio correction amount is skipped down when the output of said upstream-side air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said air-fuel ratio correction amount is skipped up when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 10
Dependent Claim
75 words
A method as set forth in claim 7, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said air-fuel ratio correction amount is gradually decreased when the output of said upstream-side air-fuel ratio sensor is on the rich side and a rich integration amount by which said air-fuel ratio correction amount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 11
Dependent Claim
67 words
A method as set forth in claim 7, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the lean side.
Claim 12
Dependent Claim
49 words
A method as set forth in claim 7, Wherein said air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream-side air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 13
Independent Claim
241 words
A method 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 the steps of: determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said downstream-side air-fuel ratio sensor; calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor when said engine is in said air-fuel ratio feedback control state; determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor; changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 14
Independent Claim
241 words
A method 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 the steps of: determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said downstream-side air-fuel ratio sensor; calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor when said engine is in said air-fuel ratio feedback control state; determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor; changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 15
Dependent Claim
40 words
A method as set forth in claim 12, wherein said open loop control state is a lean air-fuel ratio driving state, said speed increasing step increasing the speed of change of said air-fuel ratio correction amount to the lean side.
Claim 16
Dependent Claim
40 words
A method as set forth in claim 12, wherein said open loop control state is a rich air-fuel ratio driving state, said speed increasing step increasing the speed of change of said air-fuel ratio correction amount to the rich side.
Claim 17
Dependent Claim
51 words
A method as set forth in claim 12, wherein said speed increasing step increases the speed of change of said air-fuel ratio correction amount only immediately after a first occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 18
Dependent Claim
56 words
A method as set forth in claim 12, wherein said speed increasing step increases the speed of change of said air-fuel ratio correction amount from a first occurrence of said switching to a second occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 19
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 upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising: means for determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said upstream-side and downstream-side air-fuel ratio sensors; means for calculating an air-fuel ratio correlation amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said engine is in said air-fuel ratio feedback control state; means for determining whether or not a switching from the rich side to the lean side and switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor ; means for changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; means for increasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 20
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 upstream-side and downstream-side air-fuel ratio sensors disposed upstream and downstream, respectively, of said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, comprising: means for determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said upstream-side and downstream-side air-fuel ratio sensors; means for calculating an air-fuel ratio correlation amount in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said engine is in said air-fuel ratio feedback control state; means for determining whether or not a switching from the rich side to the lean side and switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor ; means for changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; means for increasing the speed of changing said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 21
Dependent Claim
39 words
An apparatus as set forth in claim 17, wherein said loop control state is a lean air-fuel ratio driving state, said speed increasing means increasing the speed of change of said air-fuel ratio correction amount to the lean side.
Claim 22
Dependent Claim
40 words
An apparatus as set forth in claim 17 wherein said open loop control state is a rich air-fuel ratio driving state, said speed increasing means increasing the speed of change of said air-fuel ratio correction amount to the rich side.
Claim 23
Dependent Claim
51 words
An apparatus as set forth in claim 17, wherein said speed increasing means increases the speed of change of said air-fuel ratio correction amount only immediately after a first occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 24
Dependent Claim
56 words
An apparatus as set forth in claim 17, wherein said speed increasing means increases the speed of change of said air-fuel ratio correction amount from a first occurrence of said switching to a second occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 25
Dependent Claim
93 words
An apparatus as set forth in claim 17, wherein said air-fuel ratio correction amount calculating means comprises: means for calculating a first air-fuel ratio correction amount in accordance with the output of said upstream-side air-fuel ratio sensor; means for calculating a second air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor; and means for calculating said air-fuel ratio correction amount in accordance with said first and second air-fuel ratio correction amounts; said speed increasing means increasing the speed of change of said second air-fuel ratio correction amount.
Claim 26
Dependent Claim
82 words
An apparatus as set forth in claim 17, wherein said air-fuel ratio correction amount calculating means comprises: means for calculating an air-fuel ratio feedback control parameter in accordance with the output of said downstream-side air-fuel ratio sensor; means for calculating said air-fuel ratio correction amount in accordance with the output of said upstream-side and air-fuel ratio sensor and said air-fuel ratio feedback control parameter, means for said speed increasing step increasing the speed of change of said air-fuel ratio feedback control parameter.
Claim 27
Dependent Claim
85 words
An apparatus as set forth in claim 23, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said air-fuel ratio correction amount is skipped down when the output of said upstream-side air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said air-fuel ratio correction amount is skipped up when the output of said downstream-side air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 28
Dependent Claim
75 words
An apparatus as set forth in claim 23, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said air-fuel ratio correction amount is gradually decreased when the output of said upstream-side air-fuel ratio sensor is on the rich side and a rich integration amount by which said air-fuel ratio correction amount is gradually increased when the output of said upstream-side air-fuel ratio sensor is on the lean side.
Claim 29
Dependent Claim
67 words
An apparatus as set forth in claim 23, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time period for delaying the output of said upstream-side air-fuel ratio sensor switched from the rich side to the lean side.
Claim 30
Dependent Claim
49 words
An apparatus as set forth in claim 23, wherein said air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream-side air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 31
Independent Claim
250 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 determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said downstream-side air-fuel ratio sensor; means for calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor when said engine is in said air-fuel ratio feedback control state; means for determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor; means for changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; means for increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 32
Independent Claim
250 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 determining whether said engine is in an air-fuel ratio feedback control state for a stoichiometric air-fuel ratio by said downstream-side air-fuel ratio sensor or in an open loop control state for said downstream-side air-fuel ratio sensor; means for calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor when said engine is in said air-fuel ratio feedback control state; means for determining whether or not a switching from the rich side to the lean side and a switching from the lean side occurs in the output of said downstream-side air-fuel ratio sensor; means for changing the air-fuel ratio correction amount in accordance with the output of said upstream-side and said downstream-side air-fuel ratio sensors; means for increasing the speed of change of said air-fuel ratio correction amount in accordance with the output of said downstream-side air-fuel ratio sensor for a predetermined time after a switching occurs in the output of said downstream-side air-fuel ratio sensor only the first time after said engine is switched from said open loop control state to said air-fuel ratio feedback control state; and means for adjusting an actual air-fuel ratio in accordance with said air-fuel ratio correction amount.
Claim 33
Dependent Claim
40 words
An apparatus as set forth in claim 28, wherein said open loop control state is a lean air-fuel ratio driving state, said speed increasing means increasing the speed of change of said air-fuel ratio correction amount to the lean side.
Claim 34
Dependent Claim
40 words
An apparatus as set forth in claim 28, wherein said open loop control state is a rich air-fuel ratio driving state, said speed increasing means increasing the speed of change of said air-fuel ratio correction amount to the rich side.
Claim 35
Dependent Claim
51 words
An apparatus as set forth in claim 28, wherein said speed increasing means increases the speed of change of said air-fuel ratio correction amount only immediately after a first occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
Claim 36
Dependent Claim
56 words
An apparatus as set forth in claim 28, wherein said speed increasing means increases the speed of change of said air-fuel ratio correction amount from a first occurrence of said switching to a second occurrence of said switching after said engine is switched from said open loop control state to said air-fuel ratio feedback control state.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-10-22 | 1994-04-23 | 1994-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-22 | 1998-04-23 | 1998-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-22 | 2002-04-23 | 2002-10-23 | $7700.00 | Window Closed / Lapsed |