{
  "$type": "site.standard.document",
  "description": "Inside an engine exhaust passage, in order from the upstream side, a hydrocarbon feed valve (16), oxidation catalyst (13), and exhaust purification catalyst (14) are arranged. A first NO X purification method which lowers the air-fuel ratio of the exhaust gas flowing into the exhaust purification…",
  "path": "/patents/1006501",
  "publishedAt": "2012-01-04T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B01D53/94",
    "TOYOTA MOTOR CO LTD [JP]"
  ],
  "textContent": "Inside an engine exhaust passage, in order from the upstream side, a hydrocarbon feed valve (16), oxidation catalyst (13), and exhaust purification catalyst (14) are arranged. A first NO X purification method which lowers the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (14) by a predetermined period while maintaining it lean so as to remove NO X without causing NO X to be stored in the form of nitrates and a second NO X purification method which switches the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (14) from lean to rich by a period longer than the above period so as to remove NO X are selectively used in accordance with an operating state of the engine.",
  "title": "METHOD OF OPERATING AN EXHAUST PURIFICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE"
}