Cylinder air-charge estimation for advanced intake valve operation in variable cam timing engines
✍ Scribed by Mrdjan Jankovic; Steve W. Magner
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 339 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0389-4304
No coin nor oath required. For personal study only.
✦ Synopsis
High efficiency of three-way automotive catalysts is achieved by regulating cylinder air-fuel ratio in a narrow band around the stoichiometry. Due to a delay present in the exhaust gas oxygen sensor signal, performance of the air-fuel ratio regulation depends on accuracy of the cylinder air-charge estimate. Variable cam timing (VCT) introduces a challenge to the air-charge estimator due to its effect on engine pumping and, in some cases, due to unmeasured back-flow of the exhaust gas into the intake manifold. The objective of this paper is to illuminate some of these issues and suggest methods to improve accuracy of air-charge estimation in VCT engines.