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Abnormality diagnosis system of air-fuel ratio sensor

  • US 9,903,292 B2
  • Filed: 10/23/2015
  • Issued: 02/27/2018
  • Est. Priority Date: 10/23/2014
  • Status: Active Grant
First Claim
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1. An abnormality diagnosis system of an air-fuel ratio sensor provided in an exhaust passage of an internal combustion engine and generating a limit current corresponding to an air-fuel ratio, comprising:

  • a current detecting part detecting an output current of said air-fuel ratio sensor; and

    a sensor temperature control device controlling a temperature of said air-fuel ratio sensor,said system is programmed to control the temperature of said air-fuel ratio sensor to a first temperature by said sensor temperature control device, and to detect the output current of said air-fuel ratio sensor by said current detecting part, when said internal combustion engine controls the air-fuel ratio so that the air-fuel ratio of the exhaust gas flowing around said air-fuel ratio sensor becomes a rich air-fuel ratio in the state where the temperature of said air-fuel ratio sensor is made the first temperature,said system is programmed to control the temperature of said air-fuel ratio sensor to a second temperature higher than said first temperature by said sensor temperature control device, and to detect the output current of said air-fuel ratio sensor by said current detecting part, when said internal combustion engine controls the air-fuel ratio so that the air-fuel ratio of the exhaust gas flowing around said air-fuel ratio sensor becomes a rich air-fuel ratio in the state where the temperature of said air-fuel ratio sensor is made said second temperature, andsaid system is programmed to judge that said air-fuel ratio sensor has become abnormal when the output current when controlling the temperature of said air-fuel ratio sensor to said first temperature is larger than the output current when controlling the temperature of said air-fuel ratio sensor to said second temperature by a predetermined value or more.

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