What Is The Function Of An Oxygen Sensor

In order to achieve high exhaust purification rate and reduce the composition of (CO) carbon monoxide, (HC) hydrocarbons, and (NOx) nitrogen oxides in the exhaust of an electronic fuel injection vehicle, a three-way catalytic converter must be used. But in order to effectively use the three-way catalytic converter, it is necessary to precisely control the air-fuel ratio so that it always approaches the theoretical air-fuel ratio. The catalytic converter is usually installed between the exhaust manifold and the muffler. The oxygen sensor has a characteristic that the output voltage has a sudden change near the theoretical air-fuel ratio (14.7:1). This characteristic is used to detect the concentration of oxygen in the exhaust and provide feedback to the computer to control the air-fuel ratio. When the actual air-fuel ratio increases, the concentration of oxygen in the exhaust increases, and the oxygen sensor notifies the ECU of the lean state of the mixture (small electromotive force: O volts). When the air-fuel ratio is lower than the theoretical air-fuel ratio, the concentration of oxygen in the exhaust decreases, and the status of the oxygen sensor (large electromotive force: 1 volt) notifies the (ECU) computer.
The ECU determines whether the air-fuel ratio is low or high based on the difference in electromotive force from the oxygen sensor, and correspondingly controls the duration of fuel injection. However, if the oxygen sensor malfunctions and the output electromotive force is abnormal, the (ECU) computer cannot accurately control the air-fuel ratio. So oxygen sensors can also compensate for errors in the air-fuel ratio caused by wear and tear of mechanical and other components of the electronic fuel injection system. It can be said that it is the only intelligent sensor in the electronic fuel injection system.
The function of the sensor is to determine whether there is excess oxygen in the exhaust after combustion of the engine, that is, the oxygen content, and convert the oxygen content into a voltage signal to transmit to the engine computer, enabling the engine to achieve closed-loop control with the goal of excessive air factor; Ensure that the three-way catalytic converter has the maximum conversion efficiency for the three pollutants of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOX) in the exhaust, and maximize the conversion and purification of emitted pollutants.