What is the difference between an air flow meter and an intake pressure sensor?

The intake flow meter measures the intake flow behind the air cleaner and in front of the throttle valve, while the intake pressure sensor measures the pressure of the intake manifold. There is generally no air flow meter in the car. Mainly look at the intake pressure sensor. Generally, the intake pressure sensor and the temperature sensor are integrated. Needless to say, everything has its role.

There are two types of EFI engines, one is L-type (air flowmeter) and the other is D-type (intake pressure sensor), which directly detects intake air.

The intake pressure sensor indirectly calculates the intake air volume, the air flowmeter is installed in front of the throttle, and the intake pressure sensor is installed behind the throttle. The intake air volume is calculated by the vacuum degree after the throttle opening changes, and the vacuum degree is small after the throttle opening is large. The throttle opening is small, and the vacuum behind it is large. Intake pressure sensors are piezoresistive, capacitive and resistive.

When the air flow meter is used, the airflow pushes the turbine blades to rotate through the flow meter. The number of revolutions of the impeller is proportional to the volume of gas passing through the air flow meter. A specially designed patent guide frame is installed at the entrance of the flowmeter, which accelerates the airflow entering the flowmeter with the increase of flow velocity.

The design of the guide frame can eliminate any potential fluid disturbance, such as eddy current or asymmetric flow. The driving force of the turbine blades also increases. It ensures that the flowmeter can accurately measure even in the case of small flow within the allowable error range.

The airflow acting on the turbine blades is axial, and the turbine is installed on the main transmission shaft, which is equipped with high-strength ball bearings. After the gas passes through the turbine blades, the rotation of the turbine blades is slowed down by the gear set. The pressure in the inlet channel of air flowmeter is restored, and the channel design can ensure the optimization of flow pattern.