I. The Function of Oxygen Sensors
Oxygen sensors are vital components of automotive emission control systems. Their function is to monitor the concentration of oxygen in the exhaust pipe and use this information to determine the fuel injection quantity of the injectors, thereby controlling the air-fuel ratio to achieve optimal exhaust gas conditions.
Maintaining the Air-Fuel Ratio The oxygen sensor controls the fuel injection quantity of the injectors by monitoring the oxygen concentration in the exhaust pipe, ensuring that the air-fuel ratio remains at its optimal level. This helps to keep the levels of harmful gases in the exhaust within the limits set by national standards.
Improving Engine Performance By accurately controlling the air-fuel ratio, oxygen sensors enable more complete combustion in the engine, leading to improved efficiency, smooth operation, increased vehicle mileage, and fuel economy.
Monitoring Engine Combustion Condition Oxygen sensors can monitor the combustion condition of the engine by measuring the oxygen concentration in the exhaust pipe. This allows for timely detection of engine malfunctions, preventing further damage and ensuring the safe operation of the vehicle.
II. The Principle of Oxygen Sensors
The principle of oxygen sensors is based on the electrochemical characteristics of the oxygen sensing element. It converts the oxygen concentration in the exhaust gas into an electrical signal, which is then transmitted to the engine control system through a circuit to control the fuel injection quantity and maintain the desired air-fuel ratio.
Oxygen Sensing Element The oxygen sensing element is the core component of the oxygen sensor. It is an electrochemical element based on zirconia ceramic material. The element generates an electrical signal by surface adsorption and dissociation of oxygen ions. Under high-temperature conditions, when the oxygen concentration is high, oxygen ions are released from the surface, generating a weak voltage signal. Conversely, when the oxygen concentration is low, oxygen ions adsorb onto the surface, generating an opposite voltage signal.
Transmission of Electrical Signal The voltage signal generated by the oxygen sensing element is very weak and requires amplification and filtering through a circuit before it can be transmitted to the engine control system. Typically, the circuitry of an oxygen sensor includes signal amplifiers, filters, voltage regulators, and other components.
Adjustment by the Control System After receiving the electrical signal from the oxygen sensor, the engine control system adjusts the fuel injection quantity of the injectors based on the signal’s magnitude and trend, thereby controlling the air-fuel ratio. By continuously adjusting the air-fuel ratio, the engine’s combustion becomes more complete, improving efficiency, performance, and reducing harmful emissions, thus achieving environmental objectives.
In conclusion, oxygen sensors are crucial components of automotive emission control systems. They monitor the concentration of oxygen in the exhaust pipe to determine the fuel injection quantity, thereby controlling the air-fuel ratio and achieving optimal exhaust gas conditions.