Modern environmental regulations are very strict, and exhaust gas composition standards are clearly defined. That is why special devices are used in modern automotive industry. These are catalytic converters, under the influence of which the level of toxic substances in the exhaust is significantly reduced. Unfortunately, such devices work well only under certain conditions. That's what an oxygen sensor is for. This small detail performs a very important function.
What is an oxygen sensor?
The optimal composition of the fuel-air mixture is when 1 part of fuel accounts for approximately 14.7 parts of air. In this case, the excess air ratio (L) is equal to 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 porous material. Its main component is zirconium dioxide. From aboveThe item is platinum coated. Such a device responds to the difference between the oxygen content in the atmosphere and exhaust gases. In addition, at the output, it generates an appropriate potential difference.
The principle of operation of this probe is quite simple. With a decrease in the level of oxygen in the exhaust, zirconium dioxide reduction reactions are triggered. By the way, platinum is the catalyst for such a transformation. And since reduction reactions alternate with oxidative processes on the surface of the sensor, the integrity and performance of the probe is maintained automatically.
Today, there are several basic models of such devices. The most popular is the Bosch oxygen sensor. This device is characterized by high sensitivity and performance.
Two-point oxygen sensor
This is one of the main models of such a device. The probe is mounted both in front of the neutralizer and behind it, which makes it possible to more clearly fix the coefficient of excess air. 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 by generating potential. The higher the oxygen content in the exhaust, the lower the voltage generated.
When the oxygen level in the air-fuel mixture drops and the voltage becomes high, an electrical signal is generated and transmitted to the engine control system.
Broadbandoxygen sensor
This device is slightly different from the previous one both in structure and in the principles of operation. It consists of two ceramic parts: a conventional two-point probe and a pumping part. A voltage of 450 mV is constantly generated between the two electrodes in the two-point part of the probe. At the same time, oxygen from the exhaust gases passes through the pumping 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 VAZ oxygen sensor works exactly according to this scheme.
