US5069035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Misfire detecting system in double air-fuel ratio sensor system
Assignee: Toyota Motor Corp
•
Filing: 1990-09-07
•
Granted: 1991-12-03
•
Expires: 2010-09-07
Abstract
Abstract In a double air-fuel ratio sensor system having two air-fuel ratio sensors upstream and downstream of a catalyst converter, a main air-fuel ratio correction amount is calculated in accordance with the output of the upstream air-fuel ratio sensor, and a sub air-fuel ratio correction amount is calculated in accordance with the output of the downstream air-fuel ratio sensor, thereby adjusting an air-fuel ratio using the two air-fuel ratio correction amounts. When the sub air-fuel ratio correction reaches a lean limit value, an ignition system is determined to be abnormal and a misfire may occur.
Inventors
- 👤 Nobuaki Kayanuma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:15
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/22; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/24; F02D41/2406; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D2200/00; F02D2200/02; F02D2200/10; F02D2200/1015; F02D41/1497; F02D41/1498; F02D41/2477; F02D41/2483; F02P; F02P11/00; F02P11/06; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
200 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output or said upstream air-fuel ratio sensor is on the lean side; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; determining whether or not said sub air-fuel ratio correction amount has reached a lean limit value; and determining that an ignition system of said engine is abnormal and a misfire may occur when said sub air-fuel ratio correction amount reaches said lean limit value.
Claim 2
Independent Claim
200 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output or said upstream air-fuel ratio sensor is on the lean side; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; determining whether or not said sub air-fuel ratio correction amount has reached a lean limit value; and determining that an ignition system of said engine is abnormal and a misfire may occur when said sub air-fuel ratio correction amount reaches said lean limit value.
Claim 3
Dependent Claim
32 words
A method as set forth in claim 1, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air fuel ratio correction is calculated.
Claim 4
Dependent Claim
88 words
A method as set forth in claim 2, wherein said air fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 5
Dependent Claim
77 words
A method as set forth in claim 2, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 6
Dependent Claim
65 words
A method as set forth in claim 2, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 7
Dependent Claim
50 words
A method as set forth in claim 2, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 8
Independent Claim
311 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; determining whether or not said engine is in a misfiring state; determining whether or not said main air-fuel ratio correction amount is within a first predetermined range when said engine is in a misfiring state; determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; determining that an ignition system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and determining that a fuel system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 9
Independent Claim
311 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; determining whether or not said engine is in a misfiring state; determining whether or not said main air-fuel ratio correction amount is within a first predetermined range when said engine is in a misfiring state; determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; determining that an ignition system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and determining that a fuel system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 10
Dependent Claim
79 words
A method as set forth in claim 7, wherein said misfiring determining step comprises the steps of: determining whether or not said engine is in a deceleration state; and determining whether or not a reduction in speed of said engine is larger than a predetermined amount when said engine is not in a deceleration state, thereby determining that said engine is in a misfiring state when the reduction in speed of said engine is larger than said predetermined amount.
Claim 11
Dependent Claim
31 words
A method as set forth in claim 7, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air-fuel ratio correction is calculated.
Claim 12
Dependent Claim
87 words
A method as set forth in claim 9, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 13
Dependent Claim
77 words
A method as set forth in claim 9, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 14
Dependent Claim
65 words
A method as set forth in claim 9, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 15
Dependent Claim
50 words
A method as set forth in claim 9, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 16
Independent Claim
338 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; calculating a learning correction amount so that a mean value of said main air-fuel ratio correction amount is brought close to a predetermined value; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main air-fuel ratio correction amount; said learning correction amount, and said sub air-fuel ratio correction amount; determining whether or not said engine is in a misfiring state; determining whether or not said learning correction amount is within a first predetermined range when said engine is in a misfiring state; determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; determining that an ignition system of said engine is abnormal and a misfire may occur when said learning correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and determining that a fuel system of said engine is abnormal and a misfire may occur when said learning correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 17
Independent Claim
338 words
A method of controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, and upstream and downstream 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: decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; calculating a learning correction amount so that a mean value of said main air-fuel ratio correction amount is brought close to a predetermined value; decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; adjusting an actual air-fuel ratio in accordance with said main air-fuel ratio correction amount; said learning correction amount, and said sub air-fuel ratio correction amount; determining whether or not said engine is in a misfiring state; determining whether or not said learning correction amount is within a first predetermined range when said engine is in a misfiring state; determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; determining that an ignition system of said engine is abnormal and a misfire may occur when said learning correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and determining that a fuel system of said engine is abnormal and a misfire may occur when said learning correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 18
Dependent Claim
79 words
A method as set forth in claim 14, wherein said misfiring determining step comprises the steps of: determining whether or not said engine is in a deceleration state; and determining whether or not a reduction in speed of said engine is larger than a predetermined amount when said engine is not in a deceleration state, thereby determining that said engine is in a misfiring state when the reduction in speed of said engine is larger than said predetermined amount.
Claim 19
Dependent Claim
31 words
A method as set forth in claim 14, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air-fuel ratio correction is calculated.
Claim 20
Dependent Claim
87 words
A method as set forth in claim 16, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 21
Dependent Claim
77 words
A method as set forth in claim 16, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 22
Dependent Claim
65 words
A method as set forth in claim 16, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 23
Dependent Claim
50 words
A method as set forth in claim 16, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 24
Independent Claim
211 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; means for determining whether or not said sub air-fuel ratio correction amount reaches a lean limit value; and means for determining that an ignition system of said engine is abnormal and a misfire may occur when said sub air-fuel ratio correction amount reaches said lean limit value.
Claim 25
Independent Claim
211 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; means for determining whether or not said sub air-fuel ratio correction amount reaches a lean limit value; and means for determining that an ignition system of said engine is abnormal and a misfire may occur when said sub air-fuel ratio correction amount reaches said lean limit value.
Claim 26
Dependent Claim
31 words
An apparatus as set forth in claim 21, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air-fuel ratio correction is calculated.
Claim 27
Dependent Claim
87 words
An apparatus as set forth in claim 22, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 28
Dependent Claim
77 words
A method as set forth in claim 22, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 29
Dependent Claim
65 words
A method as set forth in claim 22, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 30
Dependent Claim
50 words
A method as set forth in claim 22, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream 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
328 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; means for determining whether or not said engine is in a misfiring state; means for determining whether or not said main air-fuel ratio correction amount is within a first predetermined range when said engine is in a misfiring state; means for determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; means for determining that an ignition system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and means for determining that a fuel system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 32
Independent Claim
328 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main and sub air-fuel ratio correction amounts; means for determining whether or not said engine is in a misfiring state; means for determining whether or not said main air-fuel ratio correction amount is within a first predetermined range when said engine is in a misfiring state; means for determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; means for determining that an ignition system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and means for determining that a fuel system of said engine is abnormal and a misfire may occur when said main air-fuel ratio correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 33
Dependent Claim
80 words
An apparatus as set forth in claim 27, wherein said misfiring determining means comprises: means for determining whether or not said engine is in a deceleration state; and means for determining whether or not a reduction in speed of said engine is larger than a predetermined amount when said engine is not in a deceleration state, thereby determining that said engine is in a misfiring state when the reduction in speed of said engine is larger than said predetermined amount.
Claim 34
Dependent Claim
31 words
An apparatus as set forth in claim 27, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air-fuel ratio correction is calculated.
Claim 35
Dependent Claim
87 words
An apparatus as set forth in claim 29, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 36
Dependent Claim
77 words
An apparatus as set forth in claim 29, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 37
Dependent Claim
65 words
An apparatus as set forth in claim 29, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 38
Dependent Claim
50 words
An apparatus as set forth in claim 29, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
Claim 39
Independent Claim
357 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for calculating a learning correction amount so that a mean value of said main air-fuel ratio correction amount is brought close to a predetermined value; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main air-fuel ratio correction amount, said learning correction amount, and said sub air-fuel ratio correction amount; means for determining whether or not said engine is in a misfiring state; means for determining whether or not said learning correction amount is within a first predetermined range when said engine is in a misfiring state; means for determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; means for determining that an ignition system of said engine is abnormal and a misfire may occur when said learning correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and means for determining that a fuel system of said engine is abnormal and a misfire may occur when said learning correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 40
Independent Claim
357 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 and downstream 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 decreasing a main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the rich side; means for increasing said main air-fuel ratio correction amount when the output of said upstream air-fuel ratio sensor is on the lean side; means for calculating a learning correction amount so that a mean value of said main air-fuel ratio correction amount is brought close to a predetermined value; means for decreasing a sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the rich side; means for increasing said sub air-fuel ratio correction amount when the output of said downstream air-fuel ratio sensor is on the lean side; means for adjusting an actual air-fuel ratio in accordance with said main air-fuel ratio correction amount, said learning correction amount, and said sub air-fuel ratio correction amount; means for determining whether or not said engine is in a misfiring state; means for determining whether or not said learning correction amount is within a first predetermined range when said engine is in a misfiring state; means for determining whether or not said sub air-fuel ratio correction amount is within a second predetermined range when said engine is in a misfiring state; means for determining that an ignition system of said engine is abnormal and a misfire may occur when said learning correction amount is within said first predetermined range and said sub air-fuel ratio correction amount reaches a lean limit value of said second predetermined range; and means for determining that a fuel system of said engine is abnormal and a misfire may occur when said learning correction amount reaches a rich limit value or a lean limit value of said first predetermined range and said sub air-fuel ratio correction amount is within said second predetermined range.
Claim 41
Dependent Claim
80 words
An apparatus as set forth in claim 34, wherein said misfiring determining means comprises: means for determining whether or not said engine is in a deceleration state; and means for determining whether or not a reduction in speed of said engine is larger than a predetermined amount when said engine is not in a deceleration state, thereby determining that said engine is in a misfiring state when the reduction in speed of said engine is larger than said predetermined amount.
Claim 42
Dependent Claim
31 words
An apparatus as set forth in claim 34, wherein said sub air-fuel ratio correction amount is an air-fuel ratio feedback control parameter by which said main air-fuel ratio correction is calculated.
Claim 43
Dependent Claim
87 words
An apparatus as set forth in claim 36, wherein said air-fuel ratio feedback control parameter is defined by a lean skip amount by which said main air-fuel ratio correction amount is skipped down when the output of said upstream air-fuel ratio sensor is switched from the lean side to the rich side and a rich skip amount by which said main air-fuel ratio correction amount is skipped up when the output of said upstream air-fuel ratio sensor is switched from the rich side to the lean side.
Claim 44
Dependent Claim
77 words
An apparatus as set forth in claim 36, wherein said air-fuel ratio feedback control parameter is defined by a lean integration amount by which said main air-fuel ratio correction amount is gradually decreased when the output of said upstream air-fuel ratio sensor is on the rich side and a rich integration amount by which said main air-fuel ratio correction amount is gradually increased when the output of said upstream air-fuel ratio sensor is on the lean side.
Claim 45
Dependent Claim
65 words
An apparatus as set forth in claim 36, wherein said air-fuel ratio feedback control parameter is determined by a rich delay time for delaying the output of said upstream air-fuel ratio sensor switched from the lean side to the rich side and a lean delay time for delaying the output of said upstream air-fuel ratio sensor switched from the rich side to the lean side.
Claim 46
Dependent Claim
50 words
An apparatus as set forth in claim 36, wherein said main air-fuel ratio feedback control parameter is determined by a reference voltage with which the output of said upstream air-fuel ratio sensor is compared, thereby determining whether the air-fuel ratio is on the rich side or on the lean side.
References Cited (Backward Citations)
US4006718A
Cited
US4445326A
Cited
DE3339429A1
Cited
US4693076A
Cited
US4703619A
Cited
JPS61234241A
Cited
JPS6229738A
Cited
US4831838A
Cited
US4723408A
Cited
JPS62147034A
Cited
US4747265A
Cited
US4819427A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-12-02 | 1995-06-03 | 1995-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-02 | 1999-06-03 | 1999-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-12-02 | 2003-06-03 | 2003-12-03 | $7700.00 | Window Closed / Lapsed |