{
  "$type": "site.standard.document",
  "description": "A first catalyst 21 which stores or releases oxygen according to an air-fuel ratio, and a second catalyst 22 which traps or releases NOx according to the air-fuel ratio, are provided in an exhaust passage 9 of an engine 1. A controller 6 temporarily shifts the air-fuel ratio of the engine 1 to rich…",
  "path": "/patents/1106290",
  "publishedAt": "2002-03-06T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B01D53/9477",
    "NISSAN MOTOR [JP]"
  ],
  "textContent": "A first catalyst 21 which stores or releases oxygen according to an air-fuel ratio, and a second catalyst 22 which traps or releases NOx according to the air-fuel ratio, are provided in an exhaust passage 9 of an engine 1. A controller 6 temporarily shifts the air-fuel ratio of the engine 1 to rich when it is determined that the NOx trap catalyst second catalyst 22 is released. At this time, the controller 6 increases a reducing agent supply amount due to the rich shift to be larger, the larger the oxygen amount stored by the two catalysts 21, 22. In this way, the air-fuel ratio in the second catalyst 22 is maintained at a target stoichiometric or rich air-fuel ratio.",
  "title": "Engine exhaust purification device"
}