P15.10-2634-79
Example illustration of engine 260 |
1.1 | Cylinder 1 ignition coil | 1.3 | Cylinder 3 ignition coil | |
1.2 | Cylinder 2 ignition coil | 1.4 | Cylinder 4 ignition coil |
Ignition coil |
2 | Supply voltage (12 V) from circuit 87 M1 and M3 |
3 | Vehicle ground connection |
4 | Actuation |
5 | Engine ground connection |
6 | Ignition coil |
7 | High-voltage terminal (with integrated spark plug connector) |
P15.10-A014-73
Overview
This document contains information on:
General
Function
General
The ignition coils provide sufficient ignition energy under all operating conditions for the respective spark plugs.
Function
The combustion engine control unit actuates the primary coil. The primary circuit is interrupted at the moment of ignition timing point. Due to the sudden collapse of the magnetic field in the primary coil, the ignition voltage is generated in the secondary coil.
The ignition voltage reaches the spark plug via a diode, a resistor and the high-voltage terminal. The diode is fitted to suppress an additional ignition spark when the primary current is switched on.
Power is supplied to the ignition coils via circuit 87M.
Because of the diode it is not possible to measure the resistance of the secondary coil. The output stages for actuation of the ignition coils are integrated in the combustion engine control unit.
Spark plug
For each cylinder, one spark plug is screwed centrally into the cylinder head from above. The spark plugs ignite the suctioned and compressed fuel/air mixture due to arcing between the electrodes. The ignition voltage flows from the directly plugged in ignition coils to the spark plugs and causes arcing in the air gap between the central electrode and ground electrode.
All spark plug characteristics are defined by type symbols provided by the manufacturer (e.g. heat rating, seat shape, thread, size, electrode material, spark position).