Under certain conditions, a potential difference is generated by utilizing the oxygen concentration difference between the inside and outside of zirconia, and the larger the concentration difference, the greater the potential difference. The oxygen content in the atmosphere is 21%, and the exhaust gas after the combustion of a rich mixture actually does not contain oxygen. The exhaust gas generated after the combustion of a lean mixture or due to misfires contains more oxygen, but still much less than the oxygen in the atmosphere.
The working principle of oxygen sensors in cars is similar to that of dry batteries, and the zirconia element in the sensor acts like an electrolyte. The basic working principle of an oxygen sensor is to utilize the potential difference generated by the oxygen concentration difference between the inside and outside of zirconia under certain conditions, and the larger the concentration difference, the greater the potential difference. The oxygen content in the atmosphere is 21%, and the exhaust gas after the combustion of a rich mixture actually does not contain oxygen. The exhaust gas generated after the combustion of a lean mixture or due to misfires contains more oxygen, but still much less than the oxygen in the atmosphere，Under high temperature and platinum catalysis, negatively charged oxygen ions are adsorbed on the inner and outer surfaces of the zirconia sleeve. Due to the fact that there is more oxygen in the atmosphere than in the exhaust gas, more negative ions are adsorbed on the side of the sleeve that is connected to the atmosphere than on the side of the exhaust gas, resulting in an electromotive force due to the concentration difference of ions on both sides.
The oxygen sensor is an important component of fuel injection closed-loop control. Based on its feedback signal, the ECU calculates and adjusts the air-fuel ratio of the mixture in the combustion chamber to control the concentration of the mixture. In other words, the oxygen sensor detects the combustion situation of the engine. If there is more air, it sprays more fuel, and if there is less air, it sprays less fuel. Therefore, once the oxygen sensor malfunctions, it directly leads to an imbalance in the air-fuel ratio of the mixture, causing a series of problems.
Post time: Apr-03-2025