Air-fuel ratio estimator for internal combustion engine
US5569847A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 1995 |
| Grant date | Oct 29, 1996 |
| Priority date | — |
| Expiry date | Aug 22, 2015 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02D2041/1434
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
An air-fuel ratio estimator for estimating air-fuel ratio of an air and fuel mixture supplied to an internal combustion engine from an output of an air-fuel ratio sensor. In the estimator, detection response lag time of said air-fuel ratio sensor is approximated as a first-order lag time system to produce state equation from said first-order lag time system. The state equation is discretized for a period delta T to obtain a discretized state equation. A transfer function is calculated from the discretized state equation and is then an inverse transfer function is calculated from said transfer function. And correction coefficient of said inverse transfer function is determined and multiplying with inverse transfer function to the sensor output estimate an air-fuel ratio of an air and fuel mixture supplied to the engine. The correction coefficient is predetermined with respect to engine speed and is made zero at or below a predetermined engine speed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.