Ignition distributor — general information (Mercedes-Benz S-Class W126)

Ignition distributors in all cars are basically the same, with a centrifugal and vacuum regulator. The vacuum chamber is designed to adjust the ignition timing. To improve the composition of exhaust gases at idle and forced idle (coasting) the ignition timing is set in the "late" direction. Instead of contacts, the ignition distributor contains a sensor that operates on the induction principle. Depending on the engine operating conditions, the number of revolutions and the vacuum, the ignition timing is set in a known manner using centrifugal and vacuum regulators in the ignition distributor.

A rotor made of magnetically soft steel, the number of teeth of which corresponds to the number of engine cylinders, causes a change in the magnetic flux in the magnetic field created by the permanent magnet during its movement due to the teeth. Due to this, a control voltage appears in the induction coil lying in the magnetic field, depending on the value of the engine revolutions, with a value from 0.3 to 100 volts and with a sharp change of positive and negative half-waves. This sharp change in the polarity of the control voltage is used after the transition through the zero value for the formation of pulses, amplification of pulses and opening of the primary circuit in the commutator. When the primary circuit is opened, a high voltage is induced in the secondary winding of the ignition coil. Control of the angle of closure in the commutator is coordinated with the time of flow of current of the primary circuit and the number of revolutions of the engine, i.e. with an increase in the number of revolutions, the angle of the closed state also increases and, thus, a sufficiently high voltage is ensured in the region of high engine revolutions.

Material borrowed from an online resource: www.MercedesMan.ru