Gasoline and oil containing lead, sulfur, phosphorus and other impurities, will significantly reduce the performance of the sensor. And dust, oil, silicon and other ingredients will plug the sensor protective layer and the electrode. For this reason, it is necessary to improve the protective layer material and improve the deterioration resistance of the sensor element. Can be taken in the way Sensor of using the adsorption effect, good catalytic material, so that impurities are adsorbed, gathered in the protective layer and be transformed. While improving the manufacturing process by adding the appropriate materials. So that the protective layer permeability enhancement, reduce the response time.
For the automotive oxygen sensor its working environment is very bad. Work at 500 ℃ ~ 800 ℃ high temperature, usually also bear a 30 ℃ or so the impact of climate temperature. Therefore, to expand its operating temperature range, especially in the commercial temperature area of work stability, durability, as a material improvement in one direction. At the same time the whole component in a large temperature difference under the rapid changes in its reliability, degradation of the improvement is also a key issue. The general approach is to improve the electrode material, the stability of the sensitive material at high temperatures, improve the process, and improve the adhesion of the electrode to the sensitive material. Improve the environmental adaptability of oxygen sensor materials, extend the service life. Expand the air / fuel ratio control measurement area. To achieve wide area air / fuel ratio measurement control. So that the oxygen sensor can continuously measure and control Suction Control Valve the over-thick area from the air / fuel ratio to the thin area (lean area) of the entire state, to achieve plant feedback control. By the Western developed countries on the exhaust gas regulations of the strict, and thus require the oxygen sensor to measure the accuracy of the signal to improve, in order to improve the control capacity. At the same time on the instantaneous changes in the exhaust also requires timely measurement correction. Improve the accuracy of the measurement and feedback signals, and enhance the feedback control ability to the instantaneous change state. Has also become a major direction to improve material performance.
EFI engine uses a mixture of closed-loop control and three-way catalytic reactor combination of the use of technology, which is so far the most efficient way to purify the exhaust gas. The three-way catalytic converter can effectively purify three kinds of harmful gases such as CO, HC and NOx, but its purification efficiency is strictly dependent on the concentration of the mixture must be kept within the narrow range near the theoretical air-fuel ratio (14.7: 1). Once the concentration of the mixed gas deviates from this range, the ability of the three-way catalytic converter to purify the exhaust pollutant is drastically reduced. It is because the change of the air-fuel ratio causes a corresponding change in the oxygen concentration fuel metering valve in the exhaust gas, so that an oxygen sensor is provided in the exhaust pipe. Oxygen sensor at any time to detect the oxygen concentration in the exhaust, and at any time to the car's electronic control unit feedback signal. The electronic control unit adjusts the fuel injection quantity according to the feedback signal promptly. If the signal reflects the thickening of the mixed gas, the fuel injection time is reduced. On the other hand, the fuel injection time is increased, so that the air-fuel ratio of the mixed gas is always kept near the theoretical air-fuel ratio. This is the so-called engine closed-loop control.
Oxygen sensor is an essential component to achieve this closed-loop control, which plays an indispensable role in engine emission control. Modern EFI engines are typically equipped with two oxygen sensors, three-way catalytic converter efficiency monitoring, must be used in the ternary catalytic converter rear of the second oxygen sensor. When the three-way catalytic converter is working normally, the number ABS Sensor of changes in the oxygen sensor located in front of the ternary catalyst should be higher than that of the rear oxygen sensor. The monitor compares the number of changes of the front / rear oxygen sensor to determine the aging of the three-way catalytic converter no.