US4251989A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio control system
Assignee: Denso Corp
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Filing: 1979-07-10
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Granted: 1981-02-24
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Expires: 1999-07-10
Abstract
Abstract An air-fuel ratio control system comprises a comparator circuit for comparing a predetermined reference level with an output signal of a first oxygen sensor disposed upstream of a three-way catalyst for purifying the exhaust gas in the exhaust system of an internal combustion engine, the comparator circuit producing a signal indicative of whether the output signal of the first oxygen sensor is higher (lean) or lower (rich) than a predetermined air-fuel ratio, a delay circuit for delaying at least one of the output signals of the comparator circuit, and a delay time adjusting circuit for adjusting the delay time of the signal delayed by the delay circuit, in accordance with the value of the output signal of a second oxygen sensor disposed downstream of the three-way catalyst.
Inventors
- 👤 Hideaki Norimatsu
- 👤 Sigenori Isomura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:36
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1439; F02D41/1441; F02D41/1477; F02D41/1481; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
167 words
An air-fuel ratio control system comprising: first means disposed upstream of a three-way catalyst for purifying the exhaust gas in an exhaust system of an internal combustion engine, said first means detecting an oxygen concentration and producing a first signal indicative of the detected oxygen concentration; second means disposed downstream of said three-way catalyst, said second means detecting an oxygen concentration and producing a second signal indicative of the detected oxygen concentration; comparator means for comparing said first signal with a reference level associated with a predetermined air-fuel ratio in order to produce a comparison-resultant lean signal and rich signal; delay means for delaying at least one of the output signals of said comparator means; adjusting means for adjusting the delay time of the signal delayed by said delay means, in accordance with said second signal of said second means; and control means for controlling the air-fuel ratio of mixture supplied to said internal combustion engine, in accordance with the delayed signal produced from said delay means.
Claim 2
Dependent Claim
167 words
An air-fuel ratio control system comprising: first means disposed upstream of a three-way catalyst for purifying the exhaust gas in an exhaust system of an internal combustion engine, said first means detecting an oxygen concentration and producing a first signal indicative of the detected oxygen concentration; second means disposed downstream of said three-way catalyst, said second means detecting an oxygen concentration and producing a second signal indicative of the detected oxygen concentration; comparator means for comparing said first signal with a reference level associated with a predetermined air-fuel ratio in order to produce a comparison-resultant lean signal and rich signal; delay means for delaying at least one of the output signals of said comparator means; adjusting means for adjusting the delay time of the signal delayed by said delay means, in accordance with said second signal of said second means; and control means for controlling the air-fuel ratio of mixture supplied to said internal combustion engine, in accordance with the delayed signal produced from said delay means.
Claim 3
Dependent Claim
99 words
An air-fuel ratio control system according to claim 1, wherein said delay means comprises a capacitor which is charged and discharged alternately in response to the output signals of said comparator means, and a comparator for comparing signal produced across said capacitor with another reference level to thereby produce said delayed signal, and wherein said adjusting means comprises a comparator for comparing said second signal with a further reference level, and an integrator for integrating comparison-resultant output signals of said comparator of said adjusting means to thereby adjust said another reference level of said comparator of said delay means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-24 | 1984-08-25 | 1985-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-24 | 1988-08-25 | 1989-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-24 | 1992-08-25 | 1993-02-24 | $7700.00 | Window Closed / Lapsed |