Discharge electrode, esp. for spark distributors in IC engines - made of posistor semiconductor ceramic providing excellent suppression of interference at high frequencies

摘要

Theelectrode is made of resistor material resisting burning and also functioning as a suppressor resistor. At least the section (I) of the electrode transmitting the spark over the gap has a length-dependent resistance (LDR) of specified min. valve, esp. min. 400 ohm/mm. The total resistance of the electrode is pref. 0.5-1.0 kohm. Electrode pref. consists of three sections, where section (I) has the highest LDR; and the electrode is pref. made of posistor material, esp. a material based on Si; or a ceramic (A) contg. in mol.%:- 78% Al2O3; 19% Cu2O; 3% Cr2O3, and by wt. 0.2% SiO2, pressed at 1000 bars and sintered at 1250 degrees C. Several alternative designs include surface discharge electrodes employing alumina plates. Suppression is improved by more than 20 decibels and at much lower cost as compared with conventional suppression methods.