Hot film air flow meter | How to detect and solve hot wire and hot film air flow meters

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1. How much does the air pressure sensor cost?

2. Explain why the most common type of air flow meter among the four is the hot film type, not the Karman type ..

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 When the electrical signal changes and 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 airflow 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 meters: Fault codes related to air flow meters

3. What are the commonly used air flow meters

The commonly used air flow meters mainly include the following: Blade type air flow meter: Blade type air flow meter uses air flow to push and guess the rotation of the blades, and the rotation angle or speed of the blades is proportional to the air flow rate, thus achieving the measurement of air flow rate.

. Karman vortex air flow meter: Karman vortex air flow meter utilizes the principle of Karman vortex generated by fluid behind a specific shaped object (such as a cylinder), and calculates the air flow rate by measuring the frequency of vortex generation. This method has high accuracy and stability. Hot wire air flow meter: The hot wire air flow meter calculates the air flow rate by heating a thin metal wire (hot wire) and measuring the heat lost due to air flow. The faster the air flow rate, the more heat is lost by the hot wire, thus achieving measurement of flow rate. Hot film air flow me

Hot film air flow meter | How to detect and solve hot wire and hot film air flow meters

1. How much does the air pressure sensor cost?

2. Explain why the most common type of air flow meter among the four is the hot film type, not the Karman type ..

3. What are the commonly used air flow meters

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