Air/fuel ratio estimation system for internal combustion engine
US5548514A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 1995 |
| Grant date | Aug 20, 1996 |
| Priority date | — |
| Expiry date | Feb 3, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
A system for estimating air/fuel ratios in the individual cylinders of a multicylinder internal combustion engine from an output of an air/fuel ratio sensor installed at an exhaust system of the engine. In the system, the exhaust system behavior is derived by a model in which X(k) is observed from a state equation and an output equation in which an input U(k) indicates air/fuel ratios in the individual cylinder and an output Y(k) indicates of the estimated air/fuel ratio as EQU X(k+1)=AX(k)+BU(k) EQU Y(k)=CX(k)+DU(k) where A, B, C and D are coefficients. And an observer is expressed by an equation using the output Y(k) as an input and the air/fuel ratios in the individual cylinders is estimated from the state variable X. In the system, the coefficient C is set to zero for a cylinder other than most recent m (2.ltoreq.m<n) cylinders. Alternatively, a plurality of the observer matrices are prepared in advance and calculated at the same time. Depending on the engine operating condition or a valve timing switched between a plurality of characteristics one among the calculation results is selected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.