Air-fuel ratio control apparatus for internal combustion engines
US5771688A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 1996 |
| Grant date | Jun 30, 1998 |
| Priority date | — |
| Expiry date | Aug 8, 2016 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02D41/1456
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
On an exhaust pipe of an internal combustion engine, an A/F sensor is disposed at an upstream side of a three-way catalyst and a downstream side O.sub.2 sensor is disposed on a downstream side thereof. A CPU determines according to an exhaust gas temperature whether the operational state of the engine is in a high load. In an early stage of the engine operation of high load, CPU sets a "rich" side target air-fuel ratio within a range that enables the downstream side O.sub.2 sensor to make linear detection of air-fuel ratio and executes feedback control of air-fuel ratio by using the set target air-fuel ratio. Also, when the level of the load has increased, CPU sets a "rich" side target air-fuel ratio according to the exhaust gas temperature and executes feedback control of air-fuel ratio by using the set target air-fuel ratio. Further, when the "rich" width deviates from a range that enables the A/F sensor to make its detection, CPU performs open-loop control with respect to the increment in fuel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.