Adaptive time window to synchronize pre- and post-catalyst oxygen sensor switch counters
US5974786A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 21, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Jan 21, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A system and method for monitoring efficiency of a catalytic converter count switches of at least one upstream sensor interposed the engine and the converter and count switches of a downstream sensor, interposed the converter and atmosphere, during a definite time period after a switch of the at least one upstream sensor to account for propagation delay of exhaust gases traveling between the at least one upstream and downstream sensor. Upstream sensor switches may optionally be counted only if predetermined entry conditions are satisfied while downstream switches occurring during respective definite time periods after an upstream switch are counted without regard to the entry conditions. A switch ratio based on the number of switches of the at least one upstream sensor and switches of the downstream sensor is used to monitor conversion efficiency of the catalyst. The system and method may include selecting a current air flow range from a plurality of air flow ranges and associating sensor switches and/or switch ratios with corresponding air flow ranges to compensate for the propagation delay. In inferred sensor signal base on dual upstream sensors may be used to trigger the definit…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.