principle of operation

1.Oxygen sensor is a standard configuration in automobiles. It is a measuring element that uses ceramic sensitive elements to measure the oxygen potential in automobile exhaust pipes, and calculates the corresponding oxygen concentration according to the principle of chemical balance, so as to monitor and control the combustion air-fuel ratio and ensure the product quality and exhaust emission to meet the standards. Oxygen sensor is widely used in the atmosphere control of various coal combustion, oil combustion, gas combustion and other furnaces. It is the best way to measure the combustion atmosphere at present, and has the advantages of simple structure, rapid response, easy maintenance, convenient use and accurate measurement. Using this sensor to measure and control combustion atmosphere can not only stabilize and improve product quality, but also shorten production cycle and save energy.

2.The working principle of oxygen sensor in automobile is similar to that of dry battery, and the zirconia element in the sensor acts like electrolyte. Its basic working principle is: under certain conditions, the potential difference is generated by using the oxygen concentration difference between the inside and outside of zirconia, and the greater the concentration difference, the greater the potential difference. The content of oxygen in the atmosphere is 21%, and the exhaust gas after rich mixture combustion actually contains no oxygen. The exhaust gas after lean mixture combustion or exhaust gas due to lack of fire contains more oxygen, but it is still much less than the oxygen in the atmosphere. Under the catalysis of platinum at high temperature, negatively charged oxygen ions are adsorbed on the inner and outer surfaces of zirconia sleeve. Because there is more oxygen in the atmosphere than in the exhaust gas, the side communicating with the atmosphere on the casing absorbs more negative ions than that on the exhaust gas side, and the concentration difference of ions on both sides produces electromotive force.

3.When the oxygen concentration on the exhaust gas side of the automobile casing is low, a high voltage (0.6 ~ 1V) is generated between the electrodes of the oxygen sensor, and this voltage signal is sent to the automobile ECU for amplification. The ECU regards the high voltage signal as a rich mixture and 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, oxygen sensor is the key sensor for electronically controlling fuel metering. Only when the oxygen sensor is at high temperature (the end reaches more than 300°C) can its characteristics be fully reflected and the voltage can be output. At about 800°C, it has the fastest response to the change of mixture, but this characteristic will change greatly at low temperature.