US5875628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio control apparatus for internal combustion engine
Assignee: Toyota Motor Corp
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Filing: 1997-02-25
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Granted: 1999-03-02
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Expires: 2017-02-25
Abstract
Abstract In an internal combustion engine in which air-fuel ratio feedback control is performed using an A/F sensor mounted upstream of an exhaust gas purifying catalyst, a deviation in the characteristic of the A/F sensor is estimated and the air-fuel ratio feedback control and catalyst deterioration judging processes are performed accounting for the estimated deviation. If the characteristic of the A/F sensor deviates in an output increasing direction, the amount of fuel correction will become excessively large, and the period from the time an output voltage VAF crosses a target voltage VAFT to the time it returns to the target voltage will become short compared with a normally functioning A/F sensor. On the other hand, if the characteristic of the A/F sensor deviates in an output decreasing direction, the amount of fuel correction will become excessively small, and that period will become long compared with a normally functioning A/F sensor. In the present invention, the output voltage VAF of the A/F sensor is monitored, and its amplitude VP and period CPER are calculated; then, based on the relationship between them, a correction factor K for correcting VAF based on the characteristic deviation is obtained. Instead of the amplitude VP and period CPER, a response curve length and an area enclosed by VAF and VAFT may be used.
Inventors
- 👤 Noritake Mitsutani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:50
CPC Classifications
F; F01; F01N; F01N11/00; F01N11/007; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/1493; F02D41/1495; F01N2550/00; F01N2550/02; F02D41/1444; F02D41/1454; F02D41/1456; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
202 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor output correcting means for calculating an amplitude of the output of said air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output of said air-fuel ratio sensor on the basis of said amplitude and said period.
Claim 2
Dependent Claim
202 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor output correcting means for calculating an amplitude of the output of said air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output of said air-fuel ratio sensor on the basis of said amplitude and said period.
Claim 3
Dependent Claim
207 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor fault judging means for calculating an amplitude of the output of said air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said air-fuel ratio sensor on the basis of said amplitude and said period.
Claim 4
Dependent Claim
207 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor fault judging means for calculating an amplitude of the output of said air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said air-fuel ratio sensor on the basis of said amplitude and said period.
Claim 5
Dependent Claim
290 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; catalyst deterioration judging means for judging deterioration of said exhaust gas purifying catalyst on the basis of the lengths of response curves that the outputs of said upstream air-fuel ratio sensor and said downstream air-fuel ratio sensor respectively describe for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means; and response curve length correcting means for calculating an amplitude of the output of said upstream air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said upstream air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said upstream air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting on the basis of said amplitude and said period the output response curve length of said upstream air-fuel ratio sensor calculated by said catalyst deterioration judging means.
Claim 6
Dependent Claim
290 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; catalyst deterioration judging means for judging deterioration of said exhaust gas purifying catalyst on the basis of the lengths of response curves that the outputs of said upstream air-fuel ratio sensor and said downstream air-fuel ratio sensor respectively describe for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means; and response curve length correcting means for calculating an amplitude of the output of said upstream air-fuel ratio sensor, measured in reference to said target output, and a period from the time the output of said upstream air-fuel ratio sensor crosses said target output to the time said output returns to said target output, each time an inversion occurs in the output of said upstream air-fuel ratio sensor with respect to said target output during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting on the basis of said amplitude and said period the output response curve length of said upstream air-fuel ratio sensor calculated by said catalyst deterioration judging means.
Claim 7
Dependent Claim
171 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor output correcting means for calculating an output response curve length of said air-fuel ratio sensor and an area enclosed by the output of said air-fuel ratio sensor and said target output for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output of said air-fuel ratio sensor on the basis of said response curve length and said area.
Claim 8
Dependent Claim
171 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor output correcting means for calculating an output response curve length of said air-fuel ratio sensor and an area enclosed by the output of said air-fuel ratio sensor and said target output for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output of said air-fuel ratio sensor on the basis of said response curve length and said area.
Claim 9
Dependent Claim
176 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor fault judging means for calculating an output response curve length of said air-fuel ratio sensor and an area enclosed by the output of said air-fuel ratio sensor and said target output for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said air-fuel ratio sensor on the basis of said response curve length and said area.
Claim 10
Dependent Claim
176 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; and sensor fault judging means for calculating an output response curve length of said air-fuel ratio sensor and an area enclosed by the output of said air-fuel ratio sensor and said target output for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said air-fuel ratio sensor on the basis of said response curve length and said area.
Claim 11
Dependent Claim
304 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; first air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and an upstream air-fuel ratio sensor target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; second air-fuel ratio feedback control means for correcting the output of said upstream air-fuel ratio sensor on the basis of a difference between an output of said downstream air-fuel ratio sensor and a downstream air-fuel ratio sensor target output; and sensor fault judging means for calculating an upstream response curve length that the output of said upstream air-fuel ratio sensor describes, an upstream area enclosed by the output of said upstream air-fuel ratio sensor and said upstream air-fuel ratio sensor target output, and at least either a downstream response curve length that the output of said downstream air-fuel ratio sensor describes or a downstream area enclosed by the output of said downstream air-fuel ratio sensor and said downstream air-fuel ratio sensor target output, for a prescribed period during the air-fuel ratio feedback control being performed by said first and said second air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said upstream air-fuel sensor on the basis of said upstream response curve length, said upstream area, and at least either said downstream response curve length or said downstream area.
Claim 12
Dependent Claim
304 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; first air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and an upstream air-fuel ratio sensor target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; second air-fuel ratio feedback control means for correcting the output of said upstream air-fuel ratio sensor on the basis of a difference between an output of said downstream air-fuel ratio sensor and a downstream air-fuel ratio sensor target output; and sensor fault judging means for calculating an upstream response curve length that the output of said upstream air-fuel ratio sensor describes, an upstream area enclosed by the output of said upstream air-fuel ratio sensor and said upstream air-fuel ratio sensor target output, and at least either a downstream response curve length that the output of said downstream air-fuel ratio sensor describes or a downstream area enclosed by the output of said downstream air-fuel ratio sensor and said downstream air-fuel ratio sensor target output, for a prescribed period during the air-fuel ratio feedback control being performed by said first and said second air-fuel ratio feedback control means, and for judging a deviation or deterioration in the characteristic of said upstream air-fuel sensor on the basis of said upstream response curve length, said upstream area, and at least either said downstream response curve length or said downstream area.
Claim 13
Dependent Claim
247 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; and catalyst deterioration judging means for calculating an output response curve length of said upstream air-fuel ratio sensor, an output response curve length of said downstream air-fuel ratio sensor, and an area enclosed by the output of said upstream air-fuel ratio sensor and said target output, for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output response curve length of said upstream air-fuel ratio sensor on the basis of said area and the output response curve length of said upstream air-fuel ratio sensor, and judging deterioration of said exhaust gas purifying catalyst on the basis of said corrected output response curve length of said upstream air-fuel ratio sensor and the output response curve length of said downstream air-fuel ratio sensor.
Claim 14
Dependent Claim
247 words
An air-fuel ratio control apparatus for an internal combustion engine, comprising: an exhaust gas purifying catalyst mounted in an exhaust passage of said internal combustion engine; an upstream air-fuel ratio sensor mounted upstream of said exhaust gas purifying catalyst and having an output characteristic substantially proportional to an oxygen concentration in an exhaust gas; air-fuel ratio feedback control means for performing feedback control so as to bring an air-fuel ratio to a target air-fuel ratio on the basis of a difference between an output of said upstream air-fuel ratio sensor and a target output corresponding to said target air-fuel ratio; a downstream air-fuel ratio sensor mounted downstream of said exhaust gas purifying catalyst; and catalyst deterioration judging means for calculating an output response curve length of said upstream air-fuel ratio sensor, an output response curve length of said downstream air-fuel ratio sensor, and an area enclosed by the output of said upstream air-fuel ratio sensor and said target output, for a prescribed period during the air-fuel ratio feedback control being performed by said air-fuel ratio feedback control means, and for correcting the output response curve length of said upstream air-fuel ratio sensor on the basis of said area and the output response curve length of said upstream air-fuel ratio sensor, and judging deterioration of said exhaust gas purifying catalyst on the basis of said corrected output response curve length of said upstream air-fuel ratio sensor and the output response curve length of said downstream air-fuel ratio sensor.
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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) | 2002-03-01 | 2002-08-31 | 2003-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-03-01 | 2006-08-31 | 2007-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-03-01 | 2010-08-31 | 2011-03-02 | $7700.00 | Window Closed / Lapsed |