Adaptive flow restriction test method for an exhaust gas recirculation system
US6390077B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 2000 |
| Grant date | May 21, 2002 |
| Priority date | — |
| Expiry date | Sep 13, 2020 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02D2200/0406
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
An improved test method for an EGR system reliably detects debilitating EGR system restrictions without significantly degrading combustion stability and exhaust emissions. The EGR valve test opening for diagnostic purposes is initialized at a relatively low value, which is progressively increased if the resulting change in intake manifold pressure fails to exceed a threshold based on the minimum expected change in intake manifold pressure for an EGR system that is regarded as functioning within acceptable limits. As soon as the measured pressure change exceeds the threshold, the EGR system is deemed to pass the restriction test, and the test method is terminated. If the EGR valve opening reaches a maximum value without the measured pressure exceeding the threshold, the EGR system is deemed to fail the restriction test, and a fault indication is generated. Consequently, the test opening of the EGR valve is adaptively determined based on the measured intake manifold pressure change, and is never larger than required to reliably detect a debilitating EGR restriction. This allows reliable detection of a borderline failing EGR system, while preventing degradation of combustion stability…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.