Ignition map

The ignition map determines the ignition point of the individual cylinders in an engine control of a gasoline engine . The ignition map is a three-dimensional structure, consisting of the X-axis (speed), the Y-axis (engine load, usually based on the air mass, the intake manifold vacuum or the angle of the throttle valve ) and the Z-axis (ignition point). The ignition point is always calculated synchronously with the crankshaft and individually for each cylinder in relation to top dead center (TDC). When developing an engine, the ignition map is set with an application system so that the gasoline engine works optimally in every load and speed range with regard to combustion and performance. In order to achieve optimal operation of the motor, the resolution of the support points of the X and Y axes should be selected as small as possible. Because of the limited memory and the mostly used fixed point arithmetic in the engine control units, no arbitrarily small resolution of the axes of the ignition map is possible, interpolation routines are used to calculate intermediate values. These functions in the software of the motor control are usually optimized with regard to runtime in order to always deliver the correct interpolation value even at high speeds.

When applying (optimal setting) an ignition map using an application system consisting of a GUI and hardware that enables access to the engine control in real time , the calibration engineer must ensure that when setting the ignition timing, he moves in a range that Does not damage the engine. For this purpose, minimum and maximum limits for the ignition point are specified in the application system, which the application engineer cannot exceed or fall below.

literature

• Richard van Basshuysen , Fred Schäfer: Handbook internal combustion engine. Basics, components, systems, perspectives. 3rd completely revised and expanded edition. Friedrich Vieweg & Sohn Verlag / GWV Fachverlage GmbH, Wiesbaden 2005, ISBN 3-528-23933-6 .