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US4759332A
Expired / Lapsed
US
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Air-fuel ratio control system for automotive engines
Assignee: Subaru Corp
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Filing: 1986-12-04
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Granted: 1988-07-26
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Expires: 2006-12-04
Abstract
Abstract An air-fuel ratio control system for an engine has a feedback control system operated in accordance with an output voltage of an O 2 -sensor. When the output voltage becomes higher than a reference voltage, the operation of the feedback control system starts. The reference voltage is set to a high level when the engine is started, and set to a low level when a set time elapses after the starting of the engine.
Inventors
- 👤 Takuro Morozumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:16
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1479; F02D41/04; F02D41/06; F02D41/061
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
229 words
In an air-fuel ratio control system for an automotive engine, the system having an O 2 -sensor producing output voltage relative to oxygen concentration of exhaust gases of the engine, a feedback control system responsive to the output voltage of the O 2 -sensor for controlling air-fuel ratio of mixture supplied to the engine, the improvement comprising: detecting means for detecting starting of the engine and for producing an engine start signal; a timer responsive to the engine start signal for producing a first timer signal during a predetermined period of time and for producing a second timer signal after the predetermined period of time; O 2 -sensor warm-up detecting means responsive to the first timer signal for comparing the output voltage of the O 2 -sensor with a high level reference voltage and for producing a feedback control start signal when the output voltage of the O 2 -sensor exceeds the high level reference voltage, and responsive to the second timer signal for comparing the output voltage of the O 2 -sensor with a low level reference voltage which is lower than the high level reference voltage and for producing the feedback control start signal when the output voltage of the O 2 -sensor becomes higher than the low level reference voltage; means responsive to the feedback control start signal for starting operation of the feedback control system.
Claim 2
Dependent Claim
229 words
In an air-fuel ratio control system for an automotive engine, the system having an O 2 -sensor producing output voltage relative to oxygen concentration of exhaust gases of the engine, a feedback control system responsive to the output voltage of the O 2 -sensor for controlling air-fuel ratio of mixture supplied to the engine, the improvement comprising: detecting means for detecting starting of the engine and for producing an engine start signal; a timer responsive to the engine start signal for producing a first timer signal during a predetermined period of time and for producing a second timer signal after the predetermined period of time; O 2 -sensor warm-up detecting means responsive to the first timer signal for comparing the output voltage of the O 2 -sensor with a high level reference voltage and for producing a feedback control start signal when the output voltage of the O 2 -sensor exceeds the high level reference voltage, and responsive to the second timer signal for comparing the output voltage of the O 2 -sensor with a low level reference voltage which is lower than the high level reference voltage and for producing the feedback control start signal when the output voltage of the O 2 -sensor becomes higher than the low level reference voltage; means responsive to the feedback control start signal for starting operation of the feedback control system.
Claim 3
Dependent Claim
29 words
The system according to claim 1 wherein the first-mentioned detecting means is responsive to a signal from an ignition coil of the engine for producing the engine start signal.
Claim 4
Dependent Claim
20 words
The system according to claim 1 wherein the timer is a counter in which a desired number can be stored.
Claim 5
Dependent Claim
86 words
The system according to claim 1, further comprising means for storing a number representing the predetermined time when the first-mentioned detecting means does not produce the engine start signal, and said timer for decrementing the stored number to zero thereafter when the first-mentioned detecting means produces the engine start signal, whereupon said O 2 -sensor warm-up detecting means provides the low level reference voltage, and wherein, during said decrementing before zero is reached said O 2 -sensor warm-up detecting means produces the high level reference voltage.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-07-26 | 1992-01-25 | 1992-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-07-26 | 1996-01-25 | 1996-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-07-26 | 2000-01-25 | 2000-07-26 | $7700.00 | Window Closed / Lapsed |