Sensor failure diagnostic apparatus

A sensor failure diagnostic apparatus for a combustion system, comprising:

• a combustion sensor configured to sense a combustion parameter indicating a combustion state of an internal combustion engine;
• a characteristic sensor configured to sense a first characteristic parameter indicating a characteristic of a fuel used in a combustion of the internal combustion engine;
• and
• processing circuitry including at least one processor, the processing circuitry configured to:
• estimate a second characteristic parameter using the combustion parameters sensed by the combustion sensor when the combustion is executed in different combustion conditions, the first characteristic parameter and the second characteristic parameter each having a correlation with a mixing ratio of each of types of a molecular structure included in the fuel;
• and
• upon the combustion sensor being determined to be operating normally, determine whether the failure of the characteristic sensor exists, by comparing a difference between the first characteristic parameter and the second characteristic parameter with a threshold value.

A sensor failure diagnostic apparatus, comprising:

• a combustion sensor configured to sense a combustion parameter indicating a combustion state of an internal combustion engine;
• a characteristic sensor configured to sense a characteristic parameter indicating a characteristic of a fuel used in a combustion of the internal combustion engine;
• and
• processing circuitry including at least one processor, the processing circuitry configured to:
• estimate a first mixing ratio of each of types of a molecular structure included in the fuel using the combustion parameters sensed by the combustion sensor when the combustion is executed in different combustion conditions;
• estimate a second mixing ratio using the characteristic parameters sensed by the characteristic sensor;
• determine whether a failure of the combustion sensor exists by using values other than the first mixing ratio and the second mixing ratio;
• and
• upon determining that the failure of the combustion sensor does not exist, determine whether a failure of the characteristic sensor exists by comparing a difference between the first mixing ratio and the second mixing ratio with a threshold value, wherein
• the values indicate a pressure in the internal combustion engine and are sensed by the combustion sensor when the combustion is not executed in the internal combustion engine.