Combustion relevant variable determining circuit for e.g. petrol engine, has ionization measuring circuit turned-on at electrode and decoupled from ignition coil using decoupling units when ignition voltage falls below threshold voltage

摘要

The circuit has a measuring resistor and an ionization measuring circuit, which includes measuring voltage-storage units. The measuring circuit is turned-on at an ignition electrode (2) and decoupled from an ignition coil (3) using decoupling units (5, 8) when an ignition voltage falls below a threshold voltage. The storage units consist of an electrical energy storage component (7) e.g. capacitor and a voltage limiting component (6). An independent claim is also included for a method for determining combustion relevant variables in a combustion process of an internal combustion engine.