{
  "$type": "site.standard.document",
  "description": "A nitrogen oxides trapping catalytic converter (20) is provided downstream of a three-way catalytic converter (18) of an exhaust passage (31) of an engine (1). An engine control unit (21) operates the engine (1) at a stoichiometric air-fuel ratio until the three-way catalyst becomes active so as to…",
  "path": "/patents/1106234",
  "publishedAt": "2002-03-06T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B01D53/945",
    "NISSAN MOTOR [JP]"
  ],
  "textContent": "A nitrogen oxides trapping catalytic converter (20) is provided downstream of a three-way catalytic converter (18) of an exhaust passage (31) of an engine (1). An engine control unit (21) operates the engine (1) at a stoichiometric air-fuel ratio until the three-way catalyst becomes active so as to provide a minute amount of oxygen contained in the burnt gas of the fuel mixture to the zeolite catalyst which traps NOx in the presence of oxygen. After the three-way catalyst is activated, the engine (1) is operated at a lean air-fuel ratio. Due to this air-fuel ratio control, oxygen supply to the zeolite catalyst is ensured regardless of the activation state of the three-way catalyst.",
  "title": "Engine exhaust emission purifier"
}