an air flow meter Category Characteristics
Karman vortex air flow meter
The so-called Karman vortex, a means disposed in a cylindrical or triangular fluid when an object, the object is generated downstream of the two opposite directions of rotation, and alternating vortex.
Optical Karman vortex air flow meter
In the process of generating Karman vortices in the air pressure on both sides of the vortex generator will change, by action of the guide hole the metal foil, thereby to vibrate, when the light emitting diode on the vibrating metal foil, the reflection on the phototransistor receives light metal foil vortex light is modulated, the output frequency is representative of air flow rate to obtain demodulated signal.
The ultrasonic Karman vortex air flow meter
both sides of the conduit downstream of the Karman vortex generators mounted opposite the ultrasonic transmitter and reception probes. Due to the influence of the Karman vortex air density, it will transmit from the ultrasonic probe to the receiving probe more time becomes irrotational late phase difference is generated. This phase signal is processed, the vortex pulse signal can be obtained.
The hot-wire air flow meter works
When there is no air flow, the bridge is in balance, the control circuit outputs a current to the heating wire resistance RH; when when the air flow, heat is absorbed due to the RH of the air cools, its resistance value changes, the bridge is out of balance, if held hot intake air resistance constant and the temperature difference is constant, it is necessary to increase the flow resistance through the hot current IH. Therefore, the hotline current IH is a function of air mass flow.
hot film air flow meter
hot film air flow meter works with hot-wire air flow meter similar, are working with a Wheatstone bridge of. The difference is: do not use hot-film platinum wire as a hotline, but the hotlineResistor, the resistor and compensating resistor bridge constituted by a thick film fabrication on the same ceramic substrate.
vane type air flow meter
simple vane type air flow meter structure, high reliability; but larger volumes, the intake resistance is large, the response is slow.
electronically controlled fuel injection system ECU faulty storage function, operation of each of the sensor and the actuator will aggregate the fixed program stored in the computer and compared, as its error exceeds a predetermined range, i.e., a fault storage, maintenance personnel can read the specific fault by fault reader (detector).