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Patent US4738238A successfully refreshed from Google Patents.
US4738238A
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Air-fuel ratio control system for an automotive engine
Assignee: Subaru Corp
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Filing: 1987-07-31
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Granted: 1988-04-19
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Expires: 2007-07-31
Abstract
Abstract A first lookup table is provided for storing a plurality of basic fuel injection pulse widths from which one of pulse widths is derived in accordance with engine speed and intake-air pressure. A second lookup table is provided for storing a plurality of maximum correcting quantities for correcting a derived basic fuel injection pulse width in order to correct deviation of air-fuel ratio due to change of valve clearance of the engine. A necessary correcting quantity is obtained by multiplying a learning coefficient and a derived maximum correcting quantity. A desired fuel injection pulse width is obtained by adding the necessary correcting quantity to the derived basic fuel injection pulse width.
Inventors
- 👤 Hiroshi Ohishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:04
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/24; F02D41/2406; F02D41/2496; F02D41/2425; F02D41/2429; F02D41/2451; F02D41/2454; F02D41/2477
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
127 words
An air-fuel ratio control system for an automotive engine, comprising: a first lookup table storing a plurality of basic fuel injection pulse widths from which one of pulse widths is derived in accordance with engine operating conditions; a second lookup table storing a plurality of maximum correcting quantities for correcting a derived basic fuel injection pulse width in order to correct deviation of air-fuel ratio due to change of a characteristic of a device used in the engine; first means for producing a necessary correcting quantity by multiplying a learning coefficient and a maximum correcting quantity derived from the second lookup table; second means for producing a desired fuel injection pulse width in accordance with the necessary correcting quantity and the derived basic fuel injection pulse width.
Claim 2
Dependent Claim
127 words
An air-fuel ratio control system for an automotive engine, comprising: a first lookup table storing a plurality of basic fuel injection pulse widths from which one of pulse widths is derived in accordance with engine operating conditions; a second lookup table storing a plurality of maximum correcting quantities for correcting a derived basic fuel injection pulse width in order to correct deviation of air-fuel ratio due to change of a characteristic of a device used in the engine; first means for producing a necessary correcting quantity by multiplying a learning coefficient and a maximum correcting quantity derived from the second lookup table; second means for producing a desired fuel injection pulse width in accordance with the necessary correcting quantity and the derived basic fuel injection pulse width.
Claim 3
Dependent Claim
17 words
The system according to claim 1 wherein the engine operating conditions are intake-air pressure and engine speed.
Claim 4
Dependent Claim
16 words
The system according to claim 1 wherein the characteristic of a device is a valve clearance.
Claim 5
Dependent Claim
20 words
The system according to claim 1 wherein the learning coefficient is a value within a range of zero and 1.
Claim 6
Dependent Claim
29 words
The system according to claim 1 wherein the desired fuel injection pulse width is obtained by adding the necessary correcting quantity to the derived basic fuel injection pulse width.
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) | 1991-04-19 | 1991-10-19 | 1992-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-19 | 1995-10-19 | 1996-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-19 | 1999-10-19 | 2000-04-19 | $7700.00 | Window Closed / Lapsed |