modern environmental regulations are quite strict and the exhaust gas regulations are clearly defined.That is why in today's automotive industry uses special devices.This catalytic converters, which are influenced by the level of toxic substances in the exhaust is significantly reduced.Unfortunately, these devices work well only under certain conditions.That's what needs an oxygen sensor.This small detail takes a very important function.
What is the oxygen sensor?
optimum composition of the fuel-air mixture - this is when one of the fuel accounts for about 14.7 parts of air.In this case the excess air ratio (L) is equal to 1. The effective operation of the catalyst will be available only when L is equal to 1 for an error of 0.01.The main function of the sensor - is to control the composition of the fuel-air mixture.
oxygen sensor is a small device made of a porous material.Its main component is zirconia.Above the item is covered by platinum-plated.Such a device responds to the difference between the oxygen content in the atmosphere and the exhaust gas.In addition, it produces at the output a corresponding potential difference.
principle of this probe is quite simple.When the level of oxygen in the exhaust run reduction reaction zirconia.Incidentally, such a transformation catalyst is platinum.And since the sensor surface reduction reaction alternate with oxidation processes, the integrity and operability of the probe is maintained automatically.
Today, there are a few basic models of such devices.The most popular are 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 mounted as a neutralizer before, and behind it, which makes it possible to capture clearer air ratio.The electrode on one side of the device in contact with atmospheric air, and the other - with the exhaust gases in response to the generation of the potential difference.The higher oxygen content in the exhaust, the lower the generated voltage.
In cases where the oxygen level in the fuel-air mixture decreases, and the voltage becomes high, the produced electric signal, which is transmitted to the engine control system.
Broadband oxygen sensor
This device is a little different from the previous one both in structure and in principle.It consists of two ceramic parts: it is a regular two-point probe and injected part.Between the two electrodes in the two-point part of the probe is constantly generated voltage of 450 mV.At the same time, oxygen from the exhaust gas passes through the pumped part of the sensor.The lower the oxygen level, the higher the voltage between the two electrodes.In such cases, a signal is transmitted to the electronic control unit.By the way, on such a scheme works Mercedes oxygen sensor.
