How does the oxygen sensor work?

Modern environmental standards are very strict, and the standards for the composition of exhaust gases are clearly defined. That is why in the modern automobile industry special devices are used. These are catalytic converters, under the influence of which the level of toxic substances in exhausts is significantly reduced. Unfortunately, such devices work well only under certain conditions. This is why an oxygen sensor is needed. This small detail performs very important functions.

What is an oxygen sensor?

The optimal composition of the fuel-air mixture is when about 1 part of the fuel is about 14.7 parts of air. In this case, the excess air factor (L) is 1. Effective operation of the catalytic converter is possible only when L is equal to 1 with an error of 0.01. The main function of the sensor is to control the composition of the fuel-air mixture.

The oxygen sensor is a small device made of a porous material. Its main component is zirconium dioxide. The top part is covered with platinum spraying. A similar device reacts to the difference between the oxygen content in the atmosphere and the exhaust gases. In addition, at the output it generates a corresponding potential difference.

The principle of operation of this probe is quite simple. When the oxygen level in the exhausts decreases, the zirconium dioxide reduction reactions are triggered. By the way, the catalyst for such a transformation is platinum. And since on the surface of the sensor, the reduction reactions alternate with oxidative processes, the integrity and operability of the probe is maintained automatically.

To date, there are several basic models of similar devices. The most popular is the oxygen sensor Bosch. This device is characterized by high sensitivity and efficiency.

Two-point oxygen sensor

This is one of the main models of this device. The probe is attached both before the neutralizer and behind it, which makes it possible to fix the excess air factor more clearly. The electrode on one side of the device is in contact with atmospheric air, and on the other - with exhaust gases, reacting to the difference in the generation of potential. The higher the oxygen content in the exhausts, the lower the generated voltage.

In those cases when the level of oxygen in the fuel-air mixture falls and the voltage becomes high, an electrical signal is generated, which is transmitted to the engine control system.

Broadband Oxygen Sensor

This device is slightly different from the previous one both in terms of structure and principles of operation. It consists of two ceramic parts: it is a conventional point-to-point probe and a pumping part. Between two electrodes a voltage of 450 mV is constantly generated in the two-point part of the probe. At the same time, oxygen from the exhaust gases passes through the injector part of the sensor. The lower the oxygen level, the higher the voltage between the two electrodes. In such cases, the signal is transmitted to the electronic control unit. By the way, the oxygen sensor VAZ works according to this scheme.