Discrete processing catalyst monitoring
US6006153A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 1998 |
| Grant date | Dec 21, 1999 |
| Priority date | — |
| Expiry date | Oct 22, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A catalyst monitoring system is provided for monitoring catalyst efficiency in a catalytic converter of a motor vehicle. The catalyst monitoring system includes a catalyst monitor receiving electrical signals indicative of oxygen in the exhaust gas from a first oxygen sensor positioned between the vehicle's engine and the catalytic converter and a second oxygen sensor positioned downstream from the catalytic converter. Each of these input signals are filtered in the catalyst monitor such that a particular range of frequencies that encapsulate information regarding catalyst efficiency are passed. The filtered signals are then used to establish an amplitude ratio between the downstream oxygen signal and the upstream oxygen signal, such that the algorithm output linearly correlates to catalyst efficiency of the catalytic converter. Digital signal filtering is preferably implemented using a finite impulse response bandpass filter, a full-wave rectifier, a low pass filter, a sampler and a signal normalizer. A means for detecting a stabilized output signal may optionally be used in conjunction with the catalyst monitor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.