In the 1990s, pollution from cars became a hot topic. Power system sensors used to improve fuel efficiency and reduce carbon emissions have been paid more attention. After decades of development, the power system sensor has become an indispensable part of the automobile electronic control system, and the automobile emission pollution has been gradually controlled. The contribution here has to mention the oxygen sensor in the power system sensor.
Oxygen sensor is an essential component in the engine which uses a three-way catalytic converter to reduce exhaust pollution. It plays an important role in the normal operation of the engine and the effective control of exhaust emissions. There are usually two oxygen sensors, the front oxygen at the exhaust manifold and the rear oxygen behind the three-way catalyst.
The pre-oxygen feeds back the oxygen content in the exhaust gas to the engine computer, and the engine computer corrects the fuel injection amount according to this signal to adjust the mixture concentration. The task of the later oxygen is to monitor the working condition of the three-way catalytic converter. The principle is that the oxygen content behind the three-way catalytic converter is fed back to the engine computer, and the engine computer compares the signals of the two oxygen sensors. Under normal circumstances, the signal of the front oxygen sensor is higher than that of the rear oxygen sensor. If the signals of the two oxygen sensors are the same, it proves that the three-way catalytic converter is invalid.
As the air-fuel ratio of the mixture once deviation from the theoretical air-fuel ratio, the purification capacity of the three-way catalyst for CO, HC and NOx will decline sharply, so in the exhaust pipe installed oxygen sensor, to detect the oxygen concentration in the exhaust, and send a feedback signal to the ECU, and then ECU control the increase or decrease of the fuel injection of the injector, so as to control the air-fuel ratio of the mixture near the theoretical value.
When oxygen concentration is low on the exhaust side of the automobile casing, a high voltage (0.6 ~ 1V) is generated between the electrodes of the oxygen sensor. This voltage signal is sent to the automobile ECU for amplification. The ECU regards the high voltage signal as a concentrated mixture and the low voltage signal as a dilute mixture. Based on the voltage signal from the oxygen sensor, the computer diluted or enriched the mixture as close to the theoretical optimum air-fuel ratio of 14.7:1 as possible. So oxygen sensor is the key sensor of electronic control fuel metering. Oxygen sensor only at high temperature (the end reaches more than 300°C) its characteristics can be fully reflected, to output voltage. It responds fastest to changes in the mixture at about 800℃, and this property changes greatly at low temperatures.
Oxygen sensor is the standard configuration of the automobile, it is the use of ceramic sensitive element to measure the oxygen potential in the automobile exhaust pipe, calculate the corresponding oxygen concentration by the principle of chemical balance, achieve monitoring and control combustion air-fuel ratio, to ensure product quality and exhaust emission standards of the measurement element. Oxygen sensor is widely used in all kinds of coal combustion, oil combustion, gas combustion and other furnace atmosphere control, it is the best combustion atmosphere measurement method, with simple structure, rapid response, easy maintenance, easy to use, accurate measurement and other advantages. Using this sensor to measure and control combustion atmosphere can not only stabilize and improve product quality, but also shorten production cycle and save energy.
Post time: Feb-17-2023
