CPC G01N 27/409 (2013.01) [G01N 27/4072 (2013.01); G01N 27/41 (2013.01); G01N 27/419 (2013.01); G01N 33/0037 (2013.01)] | 6 Claims |
1. A gas sensor comprising a sensor element for detecting a concentration of a specific gas in a measurement-object gas, the gas sensor comprising:
an element body including an oxygen-ion-conductive solid electrolyte layer and having a measurement-object gas flow section provided therein, the measurement-object gas flow section introducing the measurement-object gas and causing the measurement-object gas to flow;
an adjustment pump cell that adjusts an oxygen concentration in an oxygen concentration adjustment chamber in the measurement-object gas flow section;
a first measurement pump cell that includes a first measurement electrode and a first outer measurement electrode and that pumps out oxygen produced in a first measurement chamber from the specific gas, the first measurement electrode being disposed in the first measurement chamber provided on a downstream side of the oxygen concentration adjustment chamber in the measurement-object gas flow section, the first outer measurement electrode being provided outside the element body so as to contact with the measurement-object gas;
a second measurement pump cell that includes a second measurement electrode and a second outer measurement electrode and that pumps out oxygen produced in a second measurement chamber from the specific gas, the second measurement electrode being disposed in the second measurement chamber provided on the downstream side of the oxygen concentration adjustment chamber in the measurement-object gas flow section, the second outer measurement electrode being provided outside the element body so as to contact with the measurement-object gas, and
a specific gas concentration detection device having a low concentration measurement mode and a high concentration measurement mode, the low concentration measurement mode being a mode on which the first measurement pump cell is controlled such that a pump current that flows in the first measurement pump cell becomes a limiting current, and, based on a value of the pump current, the specific gas concentration in the measurement-object gas is detected, the high concentration measurement mode being a mode on which the second measurement pump cell is controlled such that a pump current that flows in the second measurement pump cell becomes a limiting current, and, based on a value of the pump current, the specific gas concentration in the measurement-object gas is detected,
wherein the measurement-object gas flow section is configured such that the measurement-object gas passes through the oxygen concentration adjustment chamber and a first measurement-electrode diffusion-rate-controlling section in this order and reaches the first measurement chamber and that the measurement-object gas passes through the first measurement chamber and a second measurement-electrode diffusion-rate-controlling section in this order and reaches the second measurement chamber.
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