Speedometersensor

[Erlend]

Noen som kan forklare meg hvordan en elektronisk speedometersensor egentlig fungerer? Jeg gjetter på at det sitter en magnet inni der som "teller tenner" på tannhjulet som roterer rett under sensoren - er det i nærheten av sånn det henger sammen?

[tutte]

Det er ihvertfall slik på tråsykkel.
På HD kanskje som her; http://www.hdforums.com/forum/transmiss ... ptoms.html

[chrissenator]

Noen som kan forklare meg hvordan en elektronisk speedometersensor egentlig fungerer? Jeg gjetter på at det sitter en magnet inni der som "teller tenner" på tannhjulet som roterer rett under sensoren - er det i nærheten av sånn det henger sammen?

Du er egentlig dead on.....

A Hall effect sensor provides voltage pulses that are generated by alternately shielding the sensor from a magnetic field, then exposing it.




In electronic ignition systems, the contact breaker is eliminated and switching and triggering of the primary circuit is carried out electronically.

In Hall effect systems, a Hall effect generator can be located inside the distributor to signal an electronic control unit to turn the primary circuit "on" and "off". Hall effect generators operate by using a potential difference or voltage created when a current carrying conductor is exposed to a magnetic field.



If a magnetic field is applied at right angles to the direction of current flow in a conductor, the lines of magnetic force permeate the conductor and the electrons flowing in the conductor are deflected to one side. This deflection creates a potential difference across the conductor.

The stronger the magnetic field, the higher the voltage. This is called the Hall effect voltage, and if the magnetic field is alternately shielded, and exposed, it can be used as a switching device. Hall devices are made of semiconductor material because it produces a better effect.

In a distributor, the Hall effect generator and it's integrated circuit or IC, are located on one leg of a "U" shaped assembly, mounted on the distributor base plate.

A permanent magnet is located on the other leg and an air gap is formed between them.

An interrupter ring, which has the same number of blades and windows as engine cylinders, is rotated by the distributor shaft, moving the blades through the air gap.

When a window is aligned with the assembly, the magnetic field is at its strongest and its lines of magnetic force permeate the Hall generator and its integrated circuit. This allows the generator to switch to ground the low current signal voltage applied to it.

When the interrupter ring rotates so that the blade aligns with the assembly, the magnetic field is shielded from the generator and the signal voltage is not switched to ground.

With continuous rotation, the blades repeatedly move in and out of the air gap and the signal voltage will appear to turn on and off repeatedly. This can be used to control the operation of the ignition coil primary circuit.