Ignition Distribution — Design Description (Sierra)

Bosch Ignition Distributor

The pulse sensor with the Hall converter is located in the ignition distributor, replacing the classic interrupter. It also includes: a fixed, so-called magnetic partition and a rotor. The magnetic partition is formed by a permanent magnet fixed to a fixed plate, as well as a Hall converter located opposite the pole of the permanent magnet on a ceramic element.

The rotor has the form of a low cylinder, in the cylindrical part of which four rectangular cutouts are made. During the rotation of the rotor, its cylindrical part passes between the pole of the magnet and the Hall converter, interrupting and deflecting the magnetic flux four times per revolution, each time causing the formation or disappearance of the Hall effect. When the Hall effect disappears, the commutator transistor passes current through the primary winding of the ignition coil, and the appearance of a magnetic flux causes the Hall effect and interruption of the current flow (similar to the opening of the breaker contacts in a classic ignition distributor). At the moment of current disappearance in the primary winding, high voltage is induced in the secondary winding of the ignition coil, transmitted through the distributor to the spark plug of the corresponding cylinder.



The described solution is characterized by two important advantages: there is no mechanical wear, and therefore no adjustment is required, and the energy of the ignition spark is provided practically independently of the engine speed (in the classical system, the spark energy decreases with a high engine speed).

The Bosch transistor ignition distributor, like classic distributors, is equipped with ignition timing regulators: centrifugal and vacuum. Whereas the Lucas transistor ignition distributor does not have these regulators.

Caution! The original distributor rotor must not be replaced to maintain the correct resistance.