sensor introduce

Oxygen sensors are essential components in engines that use three-way catalytic converters to reduce exhaust pollution. Once the air-fuel ratio of the mixture deviates from the theoretical air-fuel ratio, the three-way catalyst affects CO The purification ability of HC and NOx will sharply decrease. Therefore, an oxygen sensor is installed in the exhaust pipe to detect the concentration of oxygen in the exhaust and send a feedback signal to the ECU. The ECU then controls the increase or decrease of the fuel injection amount of the fuel injector, thereby controlling the air-fuel ratio of the mixture near the theoretical value. In order to achieve high exhaust purification rate and reduce carbon monoxide (CO) in the exhaust, an electronic fuel injection vehicle is equipped The composition of (HC) hydrocarbons and (NOx) nitrogen oxides requires the use of a three-way catalytic converter. However, in order to effectively use a 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. Oxygen sensors have a characteristic, It outputs a sudden change in voltage near the theoretical air-fuel ratio (14.7:1). This characteristic is used to detect the concentration of oxygen in the exhaust and feedback it 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: 0V). When the air-fuel ratio is lower than the theoretical air-fuel ratio, the concentration of oxygen in the exhaust decreases, The status of the oxygen sensor (high 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 there is a malfunction in the oxygen sensor that causes the output electromotive force to be abnormal, The (ECU) computer cannot precisely control the air-fuel ratio. Therefore, the oxygen sensor can also compensate for the error 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 engine combustion, that is, the oxygen content, and convert the oxygen content into a voltage signal to transmit to the engine computer, Enable 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 hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOX) in the exhaust, and maximize the conversion and purification of emitted pollutants)

Installation position of oxygen sensor

The installation position of the oxygen sensor is in the exhaust pipe. Generally, the first one is installed before the three-way catalytic converter, and the second one is installed after the three-way catalytic converter. One is a sensor for detecting the combustion situation of the engine, and the other is an oxygen sensor for detecting the three-way catalytic converter. The oxygen sensor is seen to have a screw with a wire on the back of the exhaust pipe. Both oxygen sensors work normally at the same time, transmitting the collected information to the ECU and adjusting and controlling the fuel injection quantity from time to time, Ensure the normal operation of the engine. If the oxygen sensor is damaged, during driving, especially within 40 to 60 miles, the engine can be felt to shake during rapid acceleration. The degree of shaking may vary depending on the vehicle model. Note: The thread size of the oxygen sensor for automobiles is generally M18, and it is recommended to install it with a torque of 45 to 55 Nm. In addition, the exhaust pipe and oxygen sensor threads should be carefully removed, Don't be damaged. It can easily handle high temperature environments. When the oxygen sensor works, the temperature can reach 800 ℃. To prevent the oxygen sensor threads from sintering in high temperature environments, anti jamming agents need to be applied. In addition, the exhaust pipes and oxygen sensors of the vehicle are very hot after driving. To prevent burns, it is necessary to wait for the exhaust pipes to completely cool before proceeding to the next step of operation

BMW 528Li introduce

The new BMW 5 Series has a wheelbase of 3108mm; The performance surpasses that of the all-new E-Class long wheelbase version, which is basically on par with the previous generation 5 Series. The front and rear seats are comfortable due to their spacious seating experience. The conventional storage design in the car has improved compared to the old model, with good richness and practicality