VOLTAGE TRANSFORMER CIRCUIT AND METHOD FOR IONIC CURRENT MEASUREMENT OF A SPARK PLUG

摘要

A voltage transformer circuit is described for supplying a spark plug with ignition energy and for ionic current measurement. A transformer of the circuit generates a secondary voltage from a primary voltage and applies the secondary voltage to the spark plug to ignite an electric arc. Using a current effected by the secondary voltage, a capacitor is charged to a breakdown voltage of a Zener diode bridging the same, via a first branch, which leads from the transformer to a first of two sides of the capacitor. The primary voltage is disconnected from the transformer in order to extinguish the electric arc. The capacitor delivers charges for an ionic current via a second branch, which connects the second side of the capacitor to the transformer. A measuring signal of the ionic current is obtained by measuring a voltage drop at a measuring resistor.

主权项

1. A voltage transformer circuit for supplying a spark plug with ignition energy and for ionic current measurement, comprising:
a transformer having a primary side and a secondary side, the secondary side configured to generate a secondary voltage from a primary voltage applied on the primary side; a primary circuit comprising the primary side of the transformer, a connector for a primary voltage source and a switch for closing the primary circuit; and a secondary circuit comprising in a series connection a capacitor, the secondary side of the transformer, a switch-on spark suppression diode and a connector for the spark plug; wherein in the secondary circuit, the secondary side of the transformer is arranged between the capacitor and the connector for the spark plug and both the capacitor and the connector for the spark plug are each arranged between ground and the secondary side of the transformer; wherein the capacitor is bridged by a Zener diode and is arranged in a loop which connects both sides of the capacitor to the same end of the secondary side of the transformer; wherein a first circuit element is arranged in the loop on a first side of the capacitor between the capacitor and the secondary side of the transformer, said first circuit element being configured to only allow a charging current of the capacitor to pass, and a second circuit element is contained on a second side of the capacitor between the capacitor and the secondary side of the transformer, said second circuit element being configured to only allow a discharging current of the capacitor to pass.