Composition Of Oxygen Sensor

The oxygen sensor utilizes the Nernst principle.
The core component is a porous ZrO2 ceramic tube, which is a solid electrolyte with porous platinum (Pt) electrodes sintered on both sides. At a certain temperature, due to the different oxygen concentrations on both sides, oxygen molecules on the high concentration side (inner side of ceramic tube 4) are adsorbed on the platinum electrode and combine with electrons (4e) to form oxygen ions O2-, which make the electrode positively charged. O2- ions migrate to the low oxygen concentration side (exhaust gas side) through oxygen ion vacancies in the electrolyte, causing the electrode to be negatively charged, resulting in a potential difference.
When the air-fuel ratio is low (rich mixture), there is less oxygen in the exhaust gas, so there are fewer oxygen ions on the outer side of the ceramic tube, forming an electromotive force of about 1.0V;
When the air-fuel ratio is equal to 14.7, the electromotive force generated on both sides of the ceramic tube is 0.4V~0.5V, which is the reference electromotive force;
When the air-fuel ratio is high (lean mixture), the oxygen content in the exhaust gas is high, and the difference in oxygen ion concentration inside and outside the ceramic tube is small, so the generated electromotive force is very low and close to zero.
Heating type oxygen sensor:
-The heated oxygen sensor has strong resistance to lead;
-Less dependence on exhaust temperature, able to function normally under low load and low exhaust gas temperature;
-Quickly enter closed-loop control after startup
Core components of heated tubular oxygen sensor:
Heating chip type oxygen sensor chip: