Contents: Device ⇓ Operating principle ⇓
Device
The electronic contactless ignition system includes a sensor-distributor with a contactless sensor (pulse generator sensor) and high energy ignition coil.
Like the distributor of the contact ignition system, the distributor sensor of the electronic ignition system has a centrifugal and vacuum regulator of the ignition advance angle. The contactless sensor assembled with a toothed screen has the ability to rotate depending on the vacuum supplied to the vacuum regulator.
The contactless sensor includes a switch consisting of circuits for amplifying, generating and delaying voltage pulses, which are sent directly to a coil designed specifically for this ignition system.
Operating principle
The four-tooth screen mounted on the ignition distributor shaft rotates in front of three protrusions (permanent magnets) stator of the sensor. In this case, in accordance with the law of induction, an alternating voltage arises in the stator winding. The magnetic flux in the winding changes as the teeth of the screen pass in front of the stator projections. The EMF that arises in this case reaches its maximum value at the moment of the sharpest drop in the magnetic flux intensity and changes sign at the moment when the teeth of the screen and the stator projections are exactly opposite each other.
The switch controls the ignition depending on the rotation speed of the ignition distributor shaft, the voltage of the battery, the total electrical resistance of the ignition coil and, under any engine operating conditions, ensures the supply of constant voltage pulses.
When the generator sensor stops producing positive pulses, the transistor of the commutator gain circuit closes and interrupts the current supply to the primary winding of the ignition coil.
The current cutoff by the commutator transistor causes a sharp change in the magnetic flux in the ignition coil and the appearance of a high-voltage current in the secondary winding.
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The delay circuit is designed to prevent overheating of the ignition coil when the engine is stopped: after the ignition distributor shaft stops rotating, the coil power supply circuit is broken.