{
  "$type": "site.standard.document",
  "description": "When a catalyst temperature T of a catalyst device 31a is at or below a lower limit catalyst temperature Tc, the air-fuel ratio richness control is prohibited. When a first timing ti1 where an estimated value V of a NOx storage amount has reached an enrichment start threshold value Vc and a second…",
  "path": "/patents/939423",
  "publishedAt": "2016-08-10T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "F01N11/002",
    "ISUZU MOTORS LTD [JP]"
  ],
  "textContent": "When a catalyst temperature T of a catalyst device 31a is at or below a lower limit catalyst temperature Tc, the air-fuel ratio richness control is prohibited. When a first timing ti1 where an estimated value V of a NOx storage amount has reached an enrichment start threshold value Vc and a second timing ti2 based on a set interval time tic in an enrichment interval time map M1 are both satisfied, the air-fuel ratio richness control is started. The second timing ti2 is corrected by multiplying the set interval time tic by an enrichment interval correction coefficient ± preset based on the catalyst temperature T and on a storage ratio R of the estimated value V of the NOx storage amount to an enrichment start threshold value Vc of the NOx storage amount. With this, the frequency of the air-fuel ratio richness control of a catalyst device 31a configured to recover a purification capacity of a catalyst by an air-fuel ratio richness control is reduced, and the catalyst temperature T is raised while preventing the white smoke development and the HC slip, to thereby achieve improvement in exhaust gas composition and improvement in fuel efficiency.",
  "title": "EXHAUST GAS PURIFICATION SYSTEM AND EXHAUST GAS PURIFICATION METHOD"
}