{
  "$type": "site.standard.document",
  "description": "A method and apparatus for operating a lean-burn internal combustion engine (12) in co-operation with an exhaust gas purification system having a three-way catalyst (34) and a NOx trap (36) located downstream of the three-way catalyst (34) includes a controller (14) which calculates current levels…",
  "path": "/patents/1110063",
  "publishedAt": "2001-09-19T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "F01N13/009",
    "FORD GLOBAL TECH INC [US]"
  ],
  "textContent": "A method and apparatus for operating a lean-burn internal combustion engine (12) in co-operation with an exhaust gas purification system having a three-way catalyst (34) and a NOx trap (36) located downstream of the three-way catalyst (34) includes a controller (14) which calculates current levels of tailpipe NOx during lean engine operating conditions based upon the difference between a determined instantaneous feedgas NOx concentration and a determined instantaneous trap efficiency. The controller (14) discontinues lean engine operation when the tailpipe NOx, expressed in terms of either grams-per-mile or grams-per-hour, exceeds a predetermined threshold level, either instantaneously or as averaged over the course of a trap purge-fill cycle.",
  "title": "Method and system for reducing NOx tailpipe emissions of a lean-burn internation combustion engine"
}