Gas sensor and control method of 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 part formed from one end part in a longitudinal direction of the base part;
• an adjustment pump cell for adjusting an oxygen concentration in a measurement-object gas to a desired concentration, the adjustment pump cell including:
• an inner pump electrode disposed on an inner surface of the measurement-object gas flow part;
• and an outer pump electrode disposed at a position different from the measurement-object gas flow part on the base part and corresponding to the inner pump electrode;
• and
• a measurement pump cell for detecting a target gas to be measured in the measurement-object gas, the measurement pump cell including:
• an inner measurement electrode disposed at a position farther from the one end part in the longitudinal direction of the base part than the inner pump electrode on the inner surface of the measurement-object gas flow part;
• and an outer measurement electrode disposed at a position different from the measurement-object gas flow part on the base part and corresponding to the inner measurement electrode, and
• the control unit comprises:
• a pump control part for controlling operation of the adjustment pump cell and the measurement pump cell, wherein
• the pump control part is configured to perform a startup pump control at a startup of the sensor element, and a steady driving pump control at a steady drive of the sensor element after the startup,
• in the startup pump control, the pump control part is configured to apply, between the inner pump electrode and the outer pump electrode of the adjustment pump cell, a startup voltage of the adjustment pump cell that is higher than a voltage applied to the adjustment pump cell in the steady driving pump control;
• and to apply, between the inner measurement electrode and the outer measurement electrode of the measurement pump cell, a startup voltage of the measurement pump cell that is higher than a voltage applied to the measurement pump cell in the steady driving pump control and lower than the startup voltage of the adjustment pump cell,
• in the steady driving pump control, the pump control part is configured to adjust an oxygen concentration in a measurement-object gas to a desired concentration by the adjustment pump cell;
• and to detect a target gas to be measured in the measurement-object gas by the measurement pump cell, and
• a voltage ratio of the startup voltage of the adjustment pump cell to the startup voltage of the measurement pump cell is 1.03 or more and 6.00 or less.