US4770147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air-fuel ratio control system for an engine
Assignee: Subaru Corp
•
Filing: 1987-04-16
•
Granted: 1988-09-13
•
Expires: 2007-04-16
Abstract
Abstract An air-fuel ratio feedback control system is provided with a section for producing a desired air-fuel ratio dependent on engine operating conditions and with an inherent time delay calculator for producing a time delay signal. The change of the desired air-fuel ratio dependent on the change of the engine operating conditions is delayed for a period dependent on the time delay signal.
Inventors
- 👤 Yoshiyuki Sogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:28
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1477; F02D41/1481
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
192 words
An air-fuel ration control system for an engine, comprising: sensing means for sensing operating conditions and for producing operating condition signals; a sensor for sensing oxygen concentration of exhaust gas of the engine and for producing a feedback signal dependent on the concentration; first means responsive to the operating condition signals for producing a desired air-fuel ratio signal; second means responsive to the operating condition signals for producing a time delay signal representing a time delay of control operation of the system; third means responsive to the desired air-fuel ratio signal and the time delay signal for producing a corrected desired air-fuel ratio signal, the production of the corrected desired air-fuel ratio signal being delayed for a time dependent on the time delay and the corrected desired air-fuel ratio signal being changed from a small value to the desired air-fuel ratio in accordance with the time delay of control operation of the system; fourth means for comparing the feedback signal with the corrected desired air-fuel ratio signal and for producing an error signal; and control means responsive to the error signal for determining amount of fuel to be supplied to the engine.
Claim 2
Dependent Claim
192 words
An air-fuel ration control system for an engine, comprising: sensing means for sensing operating conditions and for producing operating condition signals; a sensor for sensing oxygen concentration of exhaust gas of the engine and for producing a feedback signal dependent on the concentration; first means responsive to the operating condition signals for producing a desired air-fuel ratio signal; second means responsive to the operating condition signals for producing a time delay signal representing a time delay of control operation of the system; third means responsive to the desired air-fuel ratio signal and the time delay signal for producing a corrected desired air-fuel ratio signal, the production of the corrected desired air-fuel ratio signal being delayed for a time dependent on the time delay and the corrected desired air-fuel ratio signal being changed from a small value to the desired air-fuel ratio in accordance with the time delay of control operation of the system; fourth means for comparing the feedback signal with the corrected desired air-fuel ratio signal and for producing an error signal; and control means responsive to the error signal for determining amount of fuel to be supplied to the engine.
Claim 3
Dependent Claim
26 words
The system according to the claim 1 wherein the sensor is a lean mixture sensor for sensing oxygen concentration in burnt exhaust gas of lean mixture.
Claim 4
Dependent Claim
17 words
The system according to claim 1 wherein the control means includes means for calculating fuel injection time.
Claim 5
Dependent Claim
15 words
The system according to claim 1 wherein the time delay signal includes a first-order lag.
Claim 6
Dependent Claim
16 words
The system according to claim 4 wherein the time delay signal includes a transport time delay.
Claim 7
Dependent Claim
31 words
The system according to claim 4, wherein said third means changes the corrected desired air-fuel ratio signal to the desired air-fuel ratio in accordance with the first-order lag by weight means.
Claim 8
Dependent Claim
29 words
The system according to claim 2, wherein the lean mixture sensor has a voltage output proportional to the actual air-fuel ratio in the lean mixture leaner than stoichiometric (14.7).
Claim 9
Dependent Claim
85 words
The system according to claim 1, wherein said first means comprises a first-order lag calculator and a transport time delay calculator responsive to the operating condition signals, and first and second desired ratio correcting sections respectively connected to said transport time delay calculator and first-order lag calculator, said first desired ratio correcting section is responsive to said desired air-fuel ratio signal and is connected to said second desired ratio correcting section, and said second desired ratio correcting section produces said corrected desired air-fuel ratio signal.
Claim 10
Dependent Claim
40 words
The system according to claim 1, wherein said third means in response to said time delay signal changes the corrected desired air-fuel ratio signal from the small value to the desired air-fuel ratio without oscillating about the desired air-fuel ratio.
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) | 1991-09-13 | 1992-03-14 | 1992-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-13 | 1996-03-14 | 1996-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-13 | 2000-03-14 | 2000-09-13 | $7700.00 | Window Closed / Lapsed |