What is the Principle of Oxygen Sensor?

As a GEELY Oxygen Sensor Supplier, share it with you.

In engines that use a three-way catalytic converter to reduce exhaust pollution, the oxygen sensor is an essential component. Once the air-fuel ratio of the mixed gas deviates from the theoretical air-fuel ratio, the purification ability of the three-way catalyst for CO, HC and NOx will drop sharply. Therefore, an oxygen sensor is installed in the exhaust pipe to detect the concentration of oxygen in the exhaust gas. The ECU sends a feedback signal, and then the ECU controls the increase or decrease of the fuel injection volume of the injector, so as to control the air-fuel ratio of the mixture near the theoretical value.

GEELY Oxygen Sensor

Principle

The oxygen sensor is a standard configuration on the car. It uses ceramic sensitive elements to measure the oxygen potential in the exhaust pipe of the car, and calculates the corresponding oxygen concentration by the principle of chemical balance to monitor and control the combustion air-fuel ratio to ensure product quality and exhaust Emissions up to standard measuring elements. The oxygen sensor is widely used in the atmosphere control of various types of coal combustion, oil combustion, gas combustion, etc. It is currently the best combustion atmosphere measurement method. It has the advantages of simple structure, rapid response, easy maintenance, convenient use, accurate measurement, etc. . Using the sensor to measure and control the combustion atmosphere can not only stabilize and improve product quality, but also shorten the production cycle and save energy.

The working principle of the oxygen sensor on the car is similar to that of a dry battery, and the zirconium oxide element in the sensor acts like an electrolyte. Its basic working principle is: under certain conditions, the difference in oxygen concentration between the inside and outside of zirconia is used to generate a potential difference, and the greater the concentration difference, the greater the potential difference. The oxygen content in the atmosphere is 21%. The exhaust gas after the combustion of the rich mixture does not actually contain oxygen. The exhaust gas generated after the combustion of the lean mixture or the exhaust gas generated due to lack of fire contains more oxygen, but it is still more oxygen than the atmosphere. There is much less oxygen. Under high temperature and platinum catalysis, negatively charged oxygen ions are adsorbed on the inner and outer surfaces of the zirconia sleeve. Since there is more oxygen in the atmosphere than in the exhaust gas, the side of the casing that communicates with the atmosphere adsorbs more negative ions than the side of the exhaust gas, and the difference in ion concentration on both sides generates electromotive force.

When the oxygen concentration on the exhaust side of the automobile casing is low, a high voltage (0.6~1V) is generated between the oxygen sensor electrodes, and this voltage signal is sent to the automobile ECU for amplification and processing, and the ECU regards the high voltage signal as a rich mixture. , And regard the low voltage signal as a lean mixture. According to the voltage signal of the oxygen sensor, the computer dilutes or enriches the mixture according to the theoretical optimal air-fuel ratio as close as possible to 14.7:1. Therefore, the oxygen sensor is the key sensor for electronically controlled fuel metering. Only when the oxygen sensor is at a high temperature (the end reaches 300°C or more), its characteristics can be fully reflected and can output voltage. At about 800°C, it reacts the fastest to the change of the mixture, and this characteristic will change greatly at low temperatures.

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