What is the working principle of an air flow meter

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1. What is the structure of the mainstream measurement method hot wire air flow meter?

1. Introduction to Air Flow Meter The function of an air flow meter is to measure the amount of fresh air entering the engine intake manifold and the intake temperature. Based on this information, the ECU corrects the fuel injection amount, limits smoke, and controls the EGR opening.

2. Installation Position The sensor is installed on the engine intake pipe, at the rear end of the air filter. 3. Working Principle 3.1. The principle of an air flow meter The air flow sensor integrates some electronic components on a ceramic substrate. When the engine is working normally, it first heats the diaphragm, and when fresh air flows through the sensor, it takes away some of the heat. At this time, the ECU will control the Wheatstone bridge on the diaphragm to supplement the heat, which will cause changes in the electrical signal. When the signal is transmitted to the ECU, The ECU will calculate the intake air volume based on this change. 3.2. The principle of the air temperature sensor. The intake air temperature sensor is a resistor with a negative temperature coefficient. When the intake air temperature changes, the resistance value of the resistor will change, which will cause a change in the signal voltage at the ECU end. The ECU calculates the intake air temperature based on this change. 3.3. Determination of airflow direction: There are two temperature resistors at each end of the hot film of the air flow meter. When the airflow passes through the hot film, it will take away some heat, so the temperature at the front end of the hot film is lower than that at the rear end. The ECU determines the direction of the air

flow based on this signal! 4. Circuit diagram of air flow meter. 5. Control strategy: The ECU will constantly monitor the working condition of the air flow meter. When the ECU determines that the air flow meter has a fault, it will take corresponding control measures. The bending pin is as follows: 4.1. The engine MIL light will light up, the EGR system will stop working, and the exhaust gas will no longer participate in the system operation; 4.2. The engine speed will be limited to a certain speed, resulting in limited power; 4.3. When the air flow meter malfunctions, the engine can start normally without being affected;

2. Detection of air flow meter: Fault codes related to air flow meter

2. What is the working principle of air flow meter

Air flow sensor, also known as air flow meter, is one of the important sensors of electronic fuel injection engine.

. It converts the inhaled air flow into an electrical signal and sends it to the electronic control unit (ECU), which serves as one of the basic signals for determining fuel injection and is a sensor for measuring the inhaled air flow into the engine. The structural principle of the electronic control fuel injection device is that the sensor that measures the amount of air inhaled by the engine, namely the air flow sensor, is one of the important components that determines the accuracy of system control. When the control accuracy of the air-fuel ratio (A/F) of the air and mixture sucked in by the engine is set to ± 1.0, the allowable error of the system is ± 6 [%]~7 [%]. When this allowable error is distributed to the various components of the system, the allowable error of the air flow sensor is ± 2 [%]~3 [%]. The ratio of the maximum to minimum

1. What is the structure of the mainstream measurement method hot wire air flow meter?

2. What is the working principle of air flow meter

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