{
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  "description": "An apparatus for determining an air-fuel ratio imbalance among cylinders according to the present invention comprises \"an upstream air-fuel ratio sensor 67, a catalytic converter 53, and a downstream air-fuel ratio sensor 68\" disposed at positions downstream of an exhaust gas aggregated portion…",
  "path": "/patents/1007205",
  "publishedAt": "2011-12-14T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "F02D41/0085",
    "TOYOTA MOTOR CO LTD [JP]"
  ],
  "textContent": "An apparatus for determining an air-fuel ratio imbalance among cylinders according to the present invention comprises \"an upstream air-fuel ratio sensor 67, a catalytic converter 53, and a downstream air-fuel ratio sensor 68\" disposed at positions downstream of an exhaust gas aggregated portion, calculates a sub feedback amount to have an output value of the downstream air-fuel ratio sensor coincides with a value corresponding to the stoichiometric air-fuel ratio, and performs an air-fuel ratio feedback control to have an air-fuel ratio of a mixture supplied to an engine based on the sub feedback amount and the output value of the upstream air-fuel ratio sensor. The apparatus for determining obtains a parameter for imbalance determination based on a learning value of the sub feedback amount, and determines that the air-fuel ratio imbalance among cylinders is occurring when the parameter for imbalance determination is equal to or larger than a threshold. When the number of times of update opportunity for an evaporated fuel gas concentration learning value after a start of the engine is smaller than a predetermined number of times, the parameter for imbalance determination is affected by an evaporated fuel gas purge, and therefore, the apparatus prohibits the determination of the air-fuel ratio imbalance among cylinders.",
  "title": "INTER-CYLINDER AIR/FUEL RATIO IMBALANCE JUDGMENTAL DEVICE FOR INTERNAL-COMBUSTION ENGINE"
}