Gas sensor

A gas sensor for detecting a target gas to be measured in a measurement-object gas, the gas sensor comprising a sensor element and a control unit for controlling the sensor element, wherein

• the sensor element comprises:
• a base part in an elongated plate shape, including an oxygen-ion-conductive solid electrolyte layer;
• a measurement-object gas flow cavity formed from one end part in a longitudinal direction of the base part;
• a pump cell including:
• an intracavity electrode disposed in the measurement-object gas flow cavity;
• and an extracavity electrode disposed at a position different from the measurement-object gas flow cavity on the base part and corresponding to the intracavity electrode;
• a reference gas chamber formed inside the base part, and being separated from the measurement-object gas flow cavity;
• and
• a reference electrode disposed in the reference gas chamber, and
• the control unit comprises:
• a driving control part operating the pump cell to perform a normal control for detecting the target gas to be measured in the measurement-object gas;
• a storing part storing in advance, a standard correspondence relationship of a voltage between the intracavity electrode and the reference electrode with a current flowing through the pump cell, at a standard time at which a reference potential of the reference electrode is at a predetermined value;
• and
• a diagnosing part obtaining a diagnostic correspondence relationship of a voltage between the intracavity electrode and the reference electrode with a current flowing through the pump cell at a diagnostic time at which the reference potential of the reference electrode is diagnosed, and comparing the obtained diagnostic correspondence relationship with the standard correspondence relationship stored in advance in the storing part to diagnose a deviation of the reference potential of the reference electrode at the diagnostic time from the predetermined value at the standard time, wherein
• the storing part stores in advance, as the standard correspondence relationship, a standard voltage between the intracavity electrode and the reference electrode at a time at which water (H2O) starts to be decomposed in the intracavity electrode, at the standard time at which the reference potential of the reference electrode is at the predetermined value, and
• the diagnosing part obtains, as the diagnostic correspondence relationship, a diagnostic voltage between the intracavity electrode and the reference electrode at the time at which water (H2O) starts to be decomposed in the intracavity electrode, and compares the obtained diagnostic voltage with the standard voltage stored in advance in the storing part to diagnose the deviation of the reference potential of the reference electrode at the diagnostic time from the predetermined value at the standard time.

A gas sensor for detecting a target gas to be measured in a measurement-object gas, the gas sensor comprising a sensor element and a control unit for controlling the sensor element, wherein

• the sensor element comprises:
• a base part in an elongated plate shape, including an oxygen-ion-conductive solid electrolyte layer;
• a measurement-object gas flow cavity formed from one end part in a longitudinal direction of the base part;
• a pump cell including:
• an intracavity electrode disposed in the measurement-object gas flow cavity;
• and an extracavity electrode disposed at a position different from the measurement-object gas flow cavity on the base part and corresponding to the intracavity electrode;
• a reference gas chamber formed inside the base part, and being separated from the measurement-object gas flow cavity;
• and
• a reference electrode disposed in the reference gas chamber, and
• the control unit comprises:
• a driving control part operating the pump cell to perform a normal control for detecting the target gas to be measured in the measurement-object gas;
• a storing part storing in advance, a standard correspondence relationship of a voltage between the intracavity electrode and the reference electrode with a current flowing through the pump cell, at a standard time at which a reference potential of the reference electrode is at a predetermined value;
• and
• a diagnosing part obtaining a diagnostic correspondence relationship of a voltage between the intracavity electrode and the reference electrode with a current flowing through the pump cell at a diagnostic time at which the reference potential of the reference electrode is diagnosed, and comparing the obtained diagnostic correspondence relationship with the standard correspondence relationship stored in advance in the storing part to diagnose a deviation of the reference potential of the reference electrode at the diagnostic time from the predetermined value at the standard time, wherein
• the storing part stores in advance, as the standard correspondence relationship, a standard voltage between the intracavity electrode and the reference electrode at a time at which a current flowing through the pump cell first reaches a limiting current, and
• the diagnosing part obtains, as the diagnostic correspondence relationship, a diagnostic voltage between the intracavity electrode and the reference electrode at the time at which the current flowing through the pump cell first reaches the limiting current, and compares the obtained diagnostic voltage with the standard voltage stored in advance in the storing part to diagnose the deviation of the reference potential of the reference electrode at the diagnostic time from the predetermined value at the standard time.