Definition and function of oxygen sensor
Definition:
An oxygen sensor is a measuring element that utilizes ceramic sensitive elements to measure the oxygen potential in heating furnaces or exhaust pipes. Based on the principle of chemical equilibrium, it calculates the corresponding oxygen concentration, enabling the monitoring and control of the air-fuel ratio during combustion within the furnace.
Function:
It determines whether there is excess oxygen in the exhaust after engine combustion. It converts the oxygen content into a voltage signal and transmits it to the Engine Control Unit (ECU), enabling the engine to achieve closed-loop control with the target of excess air factor.
It ensures that the three-way catalytic converter achieves maximum conversion efficiency for the three pollutants in the exhaust: hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx), thereby maximizing the conversion and purification of emissions pollutants.
Oxygen sensor classification
Oxygen sensors can be classified into various types based on their primary components and working principles, including but not limited to:
Zirconia Oxygen Sensor: This is currently the most widely used oxygen sensor, with zirconia (ZrO₂) as its main component. It converts the concentration difference between oxygen ions and oxygen molecules into a voltage signal, enabling control over the air-fuel mixture ratio in the engine. It operates within a broad temperature range, making it suitable for most automobiles.
Titania Oxygen Sensor: This type of oxygen sensor primarily comprises titania (TiO₂), and its working principle is similar to that of the zirconia sensor. However, it boasts an even wider operating temperature range, accommodating both high and low-temperature environments. Compared to the zirconia sensor, it responds more quickly, enabling more accurate monitoring of oxygen content.
Air-Fuel Ratio Sensor (AFR Sensor): The AFR sensor continuously detects the air-fuel ratio across the entire range from rich to lean mixtures. Unlike conventional oxygen sensors, it enables feedback control of the air-fuel ratio throughout the entire operating range of the engine, thereby optimizing fuel consumption, emissions, and overall engine performance in various regions. This sensor has a broad range of applications, primarily in diesel engines and hybrid vehicles.
Nitrogen Oxides Sensor (NOx Sensor): The NOx sensor is primarily used to detect the functionality of the three-way catalytic converter. When the NOx sensor detects a failure in the catalytic converter, it triggers an alarm, prompting the driver to carry out timely repairs. This sensor plays a vital role in environmental protection and emission control.
