What Is Car Nitrogen Oxide Sensor?

The automotive nitrogen oxide sensor, also known as the NOx sensor, is a key component in the automotive emission control system. It is mainly used to detect and monitor the nitrogen oxide (NOx) content in vehicle exhaust emissions. This function plays a vital role in reducing the pollution of automobile exhaust to the environment, improving fuel efficiency, and ensuring the safe operation of the vehicle. The following is a detailed analysis of the automotive nitrogen oxide sensor:

Main function

1. Detection of nitrogen oxide content: The nitrogen oxide sensor can detect the nitrogen oxide content in the engine exhaust in real time, including N2O, NO, NO2, N2O3, N2O4 and N2O5. These nitrogen oxides are one of the important pollutants in automobile exhaust and have a serious impact on the environment and human health.
2. Feedback and adjustment: The nitrogen oxide sensor feeds back the detected nitrogen oxide content information to the engine control unit (ECU). The ECU adjusts the engine’s operating parameters, such as air-fuel ratio, ignition timing, etc., based on this information to reduce nitrogen oxide emissions in exhaust gas and improve the vehicle’s environmental performance.
3. Optimize the combustion process: By precisely adjusting the ratio of air and fuel, the NOx sensor helps achieve a more efficient combustion process, which not only reduces the production of harmful emissions but also improves fuel economy.
4. Fault diagnosis and protection: When the NOx sensor detects that the exhaust emissions exceed the standard or it fails, it will immediately send an alarm to the ECU. This helps prevent the engine from continuing to operate in a bad state, avoid further deterioration of environmental pollution and ensure driving safety.
5. Basics of emission control system: The monitoring and adjustment data of the NOx sensor provides key input information for other emission control devices (such as three-way catalytic converters, particulate filters, etc.), which contributes to the effective operation of the entire emission control system.

Working principle

The working principle of the NOx sensor varies according to different types, but the basic principle is similar. Generally speaking, the NOx sensor determines the content of NOx by measuring the oxygen concentration or the difference in NOx concentration in the exhaust gas. For example, in some types of NOx sensors, oxygen and NOx in the exhaust gas reach the diffusion chamber of the sensor through a porous diffusion layer, and the oxygen pump in the sensor pumps oxygen into the diffusion chamber, making the oxygen concentration in the diffusion chamber the same as the oxygen concentration in the atmosphere.

At the same time, NOx in the exhaust gas undergoes chemical decomposition in the diffusion chamber to generate nitrogen and oxygen. The NOx sensor determines the NOx concentration in the exhaust gas by measuring the difference in oxygen concentration inside and outside the diffusion chamber.

Application Scenarios

NOx sensors are widely used in various types of vehicles, especially diesel vehicles. In the SCR (selective catalytic reduction) system of diesel vehicles, NOx sensors provide accurate NOx concentration data to ensure that the SCR system can effectively convert NOx into harmless nitrogen and water vapor. This is of great significance for meeting increasingly stringent emission regulations.

In summary, automotive NOx sensors are an important part of automotive emission control systems. They provide important guarantees for the environmental performance, fuel economy and driving safety of vehicles by detecting and monitoring the NOx content in exhaust gas.