In view of emission regulations and other requirements, maintenance-free ignition systems with sophisticated advance characteristics of high accuracy and stability are of great interest. Although recently introduced transistorized ignition systems with breakerless pick-up systems have improved the situation significantly, there is still need for improvements as regards to
1.
Introduction of further parameters controlling the advance characteristic in addition to speed and load, i.e. temperature.
2.
Higher complexity of advance curves.
3.
No changes in timing due to wear of mechanical parts of the advance mechanism.
4.
Increased accuracy of timing by pick-up at flywheel.
The paper describes the features of digital spark advance systems which offer the above mentioned advantages. It deals with three different systems, i.e.:
1.
Special purpose computer with integrated data memory.
2.
Special purpose computer with separate data memory, that is also accessible for other systems.
3.
Special purpose computer without any memory.
The characteristics of these systems are discussed.
