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Working principle of oxygen sensor

2019-06-21 Source: admin


Oxygen sensor is a device installed on the engine to reduce exhaust pollution. It can also be said that it is the filter of automobile exhaust. In today's haze, the oxygen sensor is an essential component. How can the simple and convenient oxygen sensor work and maintain?

   

The oxygen sensor is used to detect the concentration of oxygen in the exhaust gas of a certain equipment, and ECU Then the feedback is sent out ECU A sensor that controls the increase or decrease of the fuel injection quantity of the injector, so as to control the air-fuel ratio of the mixture near the theoretical value.

  Oxygen sensor

The working principle of the sensor is similar to that of the dry cell, and the zirconia element in the sensor acts as an electrolyte. Its basic working principle is: under certain conditions ( High temperature and platinum catalysis ) The potential difference is generated by the oxygen concentration difference between the inside and outside of zirconia, and the greater the concentration difference, the greater the potential difference. The oxygen content in the atmosphere is 21% In fact, the exhaust gas from the combustion of the rich mixture does not contain oxygen, while the exhaust gas generated by the combustion of the lean mixture or the exhaust gas produced by misfire contains more oxygen, but it is still much less than that in the atmosphere.

 

Under the catalysis of platinum and high temperature, oxygen ions with negative charge are adsorbed on the inner and outer surface of zirconia sleeve. Because there is more oxygen in the atmosphere than in the exhaust gas, more negative ions are adsorbed on the side connected to the atmosphere than on the side of the exhaust gas, and the concentration difference of the ions on both sides produces electromotive force. When the oxygen concentration on the exhaust side of the casing is low, a high voltage is generated between the electrodes (0 six 1V) This voltage signal is sent to ECU Zoom in, ECU The high voltage signal is regarded as the rich mixture, while the low voltage signal is regarded as the lean mixture.

 

according to Oxygen sensor The voltage signal of the computer follows as close as possible fourteen point seven one The theoretical optimum air-fuel ratio is used to dilute or enrich the mixture. Therefore, oxygen sensor is the key sensor of electronic control fuel metering. Oxygen sensors are only available at high temperatures ( End to end three hundred ° C above ) Its characteristics can be fully reflected to output voltage. It's about eight hundred ° C At low temperature, this characteristic will change greatly.



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