US4941318A — Air-fuel ratio feedback control system having sho…

Claim 1

Independent Claim 196 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, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream side air-fuel ratio sensor, comprising the steps of: determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; determining that said downstream-side air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state; determining whether or not said downstream-side air-fuel ratio sensor is short-circuited; and prohibiting the adjustment of said actual air-fuel ratio by the output of said downstream-side air-fuel ratio sensor when said downstream-side air-fuel ratio sensor is short-circuited.

Claim 2

Independent Claim 196 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, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream side air-fuel ratio sensor, comprising the steps of: determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; determining that said downstream-side air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said downstream-side air-fuel ratio sensor is in an activation state; determining whether or not said downstream-side air-fuel ratio sensor is short-circuited; and prohibiting the adjustment of said actual air-fuel ratio by the output of said downstream-side air-fuel ratio sensor when said downstream-side air-fuel ratio sensor is short-circuited.

Claim 3

Dependent Claim 96 words

A method as set forth in claim 1, wherein said short-circuit determining step comprises the steps of: determining whether or not said engine is in a starting mode; determining whether or not said engine is in a cold state; and determining whether or not the output of said downstream-side air-fuel ratio sensor is lower than a predetermined level, when said engine is in a starting mode and in a cold state; thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the output of said downstream-side air-fuel ratio sensor is lower than said predetermined level.

Claim 4

Dependent Claim 98 words

A method as set forth in claim 1, wherein said short-circuit determining step comprises the steps of: determining whether or not the output of said downstream-side air-fuel ratio sensor is lower than a predetermined level at a predetermined time period; counting the number of continuous timings when the output of said downstream-side air-fuel ratio sensor is lower than said predetermined level; determining whether or not the number of continuous timings is larger than a predetermined number, thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the number of continuous timings is larger than said predetermined number.

Claim 5

Dependent Claim 84 words

A method as set forth in claim 1, wherein said short-circuit determining step comprises the steps of: determining whether or not said engine is in a fuel enrichment state; and determining whether or not the output of said downstream-side air-fuel ratio sensor is larger than a predetermined level, when said engine is in a fuel enrichment state, thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the output of said downstream-side air-fuel ratio sensor is not once larger than said predetermined level.

Claim 6

Dependent Claim 71 words

A method as set forth in claim 1, wherein said pull-up type input circuit comprises: a resistor connected between an output of said downstream-side air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said downstream-side air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.

Claim 7

Dependent Claim 72 words

A method as set forth in claim 1, wherein said actual air-fuel ratio adjusting 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 adjusting said actual air-fuel ratio in cordance with said first and second air-fuel ratio correction amounts.

Claim 8

Dependent Claim 75 words

A method as set forth in claim 1, wherein said actual air-fuel ratio adjusting 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 an 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; and adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.

Claim 9

Dependent Claim 85 words

A method as set forth in claim 7, wherein said arr-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 184 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising the steps of: determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; determining that said air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state; determining whether or not said air-fuel ratio sensor is short-circuited; and prohibiting the adjustment of said actual air-fuel ratio by the output of said air-fuel ratio sensor when said air-fuel ratio sensor is short-circuited.

Claim 14

Independent Claim 184 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising the steps of: determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; determining that said air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when said air-fuel ratio sensor is in an activation state; determining whether or not said air-fuel ratio sensor is short-circuited; and prohibiting the adjustment of said actual air-fuel ratio by the output of said air-fuel ratio sensor when said air-fuel ratio sensor is short-circuited.

Claim 15

Dependent Claim 93 words

A method as set forth in claim 12, wherein said short-circuit determining step comprises the steps of: determining whether or not said engine is in a starting mode; determining whether or not said engine is in a cold state; and determining whether or not the output of said air-fuel ratio sensor is lower than a predetermined level, when said engine is in a starting mode and in a cold state, thereby determining that said air-fuel ratio sensor is short-circuited, when the output of said air-fuel ratio sensor is lower than said predetermined level.

Claim 16

Dependent Claim 95 words

A method as set forth in claim 12, wherein said short-circuit determining step comprises the steps of: determining whether or not the output of said air-fuel ratio sensor is lower than a predetermined level at every predetermined time period; counting the number of continuous timings when the output of said air-fuel ratio sensor is lower than said predetermined level; determining whether or not the number of continuous timings is larger than a predetermined number, thereby determining that said air-fuel ratio sensor is short-circuited, when the number of continuous timings is larger than said predetermined number.

Claim 17

Dependent Claim 81 words

A method as set forth in claim 12, wherein said short-circuit determining step comprises the steps of: determining whether or not said engine is in a fuel enrichment state; and determining whether or not the output of said air-fuel ratio sensor is larger than a predetermined level, when said engine is in a fuel enrichment state, thereby determining that said air-fuel ratio sensor is short-circuited, when the output of said air-fuel ratio sensor is not once larger than said predetermined level.

Claim 18

Dependent Claim 69 words

A method as set forth in claim 12, wherein said pull-up type input circuit comprises: a resistor connected between the output of said air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.

Claim 19

Dependent Claim 49 words

A method as set forth in claim 12, wherein said actual air-fuel ratio adjusting step comprises the steps of: calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor; and adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.

Claim 20

Independent Claim 202 words

A apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising: means for determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; means for determining that said downstream-side air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; means for adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said down-stream-side air-fuel ratio sensor is in an activation state; means for determining whether or not said downstream-side air-fuel ratio sensor is short-circuited; and means for prohibiting the adjustment of said actual air-fuel ratio by the output of said downstream-side air-fuel ratio sensor when said downstream-side air-fuel ratio sensor is short-circuited.

Claim 21

Independent Claim 202 words

A apparatus for controlling an air-fuel ratio in an internal combustion engine having a catalyst converter for removing pollutants in the exhaust gas thereof, 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, and a pull-up type input circuit for supplying a differential current to said downstream-side air-fuel ratio sensor and receiving an output of said downstream-side air-fuel ratio sensor, comprising: means for determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; means for determining that said downstream-side air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; means for adjusting an actual air-fuel ratio in accordance with the outputs of said upstream-side and downstream-side air-fuel ratio sensors when said down-stream-side air-fuel ratio sensor is in an activation state; means for determining whether or not said downstream-side air-fuel ratio sensor is short-circuited; and means for prohibiting the adjustment of said actual air-fuel ratio by the output of said downstream-side air-fuel ratio sensor when said downstream-side air-fuel ratio sensor is short-circuited.

Claim 22

Dependent Claim 99 words

An apparatus as set forth in claim 18, wherein said short-circuit determining means comprises: means for determining whether or not said engine is in a starting mode; means for determining whether or not said engine is in a cold state; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor is lower than a predetermined level, when said engine is in a starting mode and in a cold state, thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the output of said downstream-side air-fuel ratio sensor is lower than said predetermined level.

Claim 23

Dependent Claim 101 words

An apparatus as set forth in claim 18, wherein said short-circuit determining means comprises: means for determining whether or not the output of said downstream-side air-fuel ratio sensor is lower than a predetermined level at every predetermined time period; means for counting the number of continuous timings when the output of said downstream-side air-fuel ratio sensor is lower than said predetermined level; means for determining whether or not the number of continuous timings is larger than a predetermined number; thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the number of continuous timings is larger than said predetermined number.

Claim 24

Dependent Claim 85 words

An apparatus as set forth in claim 18, wherein said short-circuit determining means comprises: means for determining whether or not said engine is in a fuel enrichment state; and means for determining whether or not the output of said downstream-side air-fuel ratio sensor is larger than a predetermined level, when said engine is in a fuel enrichment state, thereby determining that said downstream-side air-fuel ratio sensor is short-circuited, when the output of said downstream-side air-fuel ratio sensor is not once larger than said predetermined level.

Claim 25

Dependent Claim 71 words

An apparatus as set forth in claim 18, wherein said pull-up type input circuit comprises: a resistor connected between an output of said downstream-side air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said downstream-side air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.

Claim 26

Dependent Claim 75 words

An apparatus as set forth in claim 18, wherein said actual air-fuel ratio adjusting 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 adjusting said actual air-fuel ratio in accordance with said first and second air-fuel ratio correction amounts.

Claim 27

Dependent Claim 78 words

An apparatus as set forth in claim 18, wherein said actual air-fuel ratio adjusting 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 an 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; and means for adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.

Claim 28

Dependent Claim 85 words

An apparatus as set forth in claim 24, 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 29

Dependent Claim 75 words

An apparatus as set forth in claim 24, 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 30

Dependent Claim 67 words

An apparatus as set forth in claim 24, 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 31

Dependent Claim 49 words

An apparatus as set forth in claim 24, 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 32

Independent Claim 190 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising: means for determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; means for determining that said air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; means for adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when air-fuel ratio sensor is in an activation state; means for determining whether or not said air-fuel ratio sensor is short-circuited; and means for prohibiting the adjustment of said actual air-fuel ratio by the output of said air-fuel ratio sensor when said air-fuel ratio sensor is short-circuited.

Claim 33

Independent Claim 190 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, an air-fuel ratio sensor disposed upstream or downstream of or within said catalyst converter, for detecting a concentration of a specific component in the exhaust gas, and a pull-up type input circuit for supplying a differential current to said air-fuel ratio sensor and receiving an output of said air-fuel ratio sensor, comprising: means for determining whether or not the output of said pull-up type input circuit is lower than a predetermined activation level; means for determining that said air-fuel ratio sensor is in an activated state after the output of said pull-up type input circuit is lower than said predetermined active level; means for adjusting an actual air-fuel ratio in accordance with the output of said air-fuel ratio sensor when air-fuel ratio sensor is in an activation state; means for determining whether or not said air-fuel ratio sensor is short-circuited; and means for prohibiting the adjustment of said actual air-fuel ratio by the output of said air-fuel ratio sensor when said air-fuel ratio sensor is short-circuited.

Claim 34

Dependent Claim 95 words

An apparatus as set forth in claim 29, wherein said short-circuit determining means comprises: means for determining whether or not said engine is in a starting mode; means for determining whether or not said engine is in a cold state; and means for determining whether or not the output of said air-fuel ratio sensor is lower than a predetermined level, when said engine is in starting mode and in a cold state, thereby determining that said air-fuel ratio sensor is short-circuited, when the output of said air-fuel ratio sensor is lower than said predetermined level.

Claim 35

Dependent Claim 98 words

An apparatus as set forth in claim 29, wherein said short-circuit determining means comprises: means for determining whether or not the output of said air-fuel ratio sensor is lower than a predetermined level at a predetermined time period; means for counting the number of continuous timings when the output of said air-fuel ratio sensor is lower than said predetermined level; means for determining whether or not the number of continuous timings is larger than a predetermined number; thereby determining that said air-fuel ratio sensor is short-circuited, when the number of continuous timings is larger than said predetermined number.

Claim 36

Dependent Claim 82 words

An apparatus as set forth in claim 29, wherein said short-circuit determining means comprises: means for determining whether or not said engine is in a fuel enrichment state; and means for determining whether or not the output of said air-fuel ratio sensor is larger than a predetermined level, when said engine is in a fuel enrichment state; thereby determining that said air-fuel ratio sensor is short-circuited, when the output of said air-fuel ratio sensor is not once larger than said predetermined level.

Claim 37

Dependent Claim 69 words

An apparatus as set forth in claim 29, wherein said pull-up type input circuit comprises: a resistor connected between the output of said air-fuel ratio sensor and a high power supply terminal; and a capacitor connected between the output of said air-fuel ratio sensor and a low power supply terminal, the connection node of said resistor and said capacitor serving as the output of said pull-up type input circuit.

Claim 38

Dependent Claim 50 words

An apparatus as set forth in claim 29, wherein said actual air-fuel ratio adjusting means comprises: means for calculating an air-fuel ratio correction amount in accordance with the output of said air-fuel ratio sensor; and means for adjusting said actual air-fuel ratio in accordance with said air-fuel ratio correction amount.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-07-16	1994-01-15	1994-07-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-07-16	1998-01-15	1998-07-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-07-16	2002-01-15	2002-07-17	$7700.00	Window Closed / Lapsed

Air-fuel ratio feedback control system having short-circuit detection for air-fuel ratio sensor

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