Oxygen sensor basic knowledge and detection and maintenance, all at once tell you!
Today we're going to talk about oxygen sensors.
First, the role of oxygen sensor
The oxygen sensor is mainly used to monitor the oxygen content in the exhaust gas of the engine after combustion, and converts the oxygen content into a voltage signal to the ECU, which analyzes and determines the concentration of the mixture according to the signal, and corrects the injection time according to the situation, so that the engine can get the best concentration of the mixture.
PS: The pre-oxygen sensor is mainly used to detect the concentration of the mixture, and the post-oxygen sensor is mainly used to compare the signal voltage with the pre-oxygen sensor to monitor the conversion effect of the three-way catalytic converter.
Second, installation position
Oxygen sensors generally come in pairs, there are two or four, installed in the exhaust pipe three-way catalytic converter before and after.
3. English abbreviation
English abbreviation: O2, O2S, HO2S
Fourth, structure classification
There are many ways to classify oxygen sensors, PS: the current oxygen sensors are heated, and the first and second lines are non-heated oxygen sensors. In addition, the oxygen sensor is also divided into upstream (front) oxygen sensor and downstream (rear) oxygen sensor according to the position (or function). More and more vehicles are now equipped with 5-wire and 6-wire broadband oxygen sensors.
Here, we mainly talk about three oxygen sensors:
Titanium oxide type:
This sensor uses the semiconductor material titanium dioxide, and its resistance value depends on the oxygen concentration in the environment around the semiconductor material titanium dioxide.
When there is more oxygen around, the resistance of titanium dioxide TiO2 increases. On the contrary, when the surrounding oxygen is relatively small, the resistance of titanium dioxide TiO2 decreases, so the resistance of titanium dioxide oxygen sensor changes sharply near the theoretical air-fuel ratio, and the output voltage also changes sharply.
Note: When the temperature is very low, the resistance value of titanium dioxide will change to infinity, so that the sensor output voltage is almost zero.
Zirconia type:
The inner and outer surfaces of zirconia tubes are coated with a layer of platinum. Under certain conditions (high temperature and platinum catalysis), the potential difference is generated by the concentration difference of oxygen on both sides of zirconia.
Broadband oxygen sensor:
It is also called air-fuel ratio sensor, broadband oxygen sensor, linear oxygen sensor, wide range oxygen sensor, etc.
PS: It is based on the heated zirconia type oxygen sensor extension.
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