Title: Ceramic distributor rotor for electromagnetic interference (EMI) control

Authors: A.L. Micheli, W.-C. Kuo, R.L. Spraguet

Addresses: Electronics Department, General Motors Research Laboratories, Warren, Michigan, USA. ' Formerly of the Electronics Department, General Motors Research Laboratories, Warren, Michigan, USA. ' Delco-Remy Division, Anderson, Indiana, USA

Abstract: Experimental studies indicate that current variations near the distributor gap are a good indicator of electromagnetic radiation (EMR) for frequencies exceeding 100 MHz. After the distributor gap breaks down, the current trace measured near the gap shows two major peaks: one when the initial process bridges the gap (streamer pulse with peak value I₁), and the other when the spark finally occurs. The value of I₁ can be related to the breakdown voltage by a relation similar to that in a corona discharge. The magnitude of I₁ is a good indicator of EMR due to the distributor gap. I₁ can be effectively suppressed by a resistive load located right at the distributor gap. For improvements of electromagnetic interference (EMI) control over current production distributor rotors, a resistive ceramic rotor composed of iron oxide doped with titania satisfies the electrical and mechanical requirements for the ignition system. Also, the ceramic rotor was found to improve in-car radio noise suppression. Tests on ceramic rotors installed in GM vehicles show satisfactory radio performance.

Keywords: automotive electronics; ceramics applications; component design; materials processing; ceramic distributor rotors; electromagnetic interference; EMI control; vehicle design.

DOI: 10.1504/IJVD.1985.061138

International Journal of Vehicle Design, 1985 Vol.6 No.6, pp.811 - 816

Published online: 25 May 2014 *

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