Snap-in type sparkplug voltage probe device for use in internal

Abstract

In a snap-in type spark plug voltage probe device, the insulator base has an upper half and a lower half, both ends of which are integrally connected by means of a flexible portion. The upper half and the lower half have a plurality of grooves in which spark plug cables are placed. The upper half and the lower half are joined together by the flexible portion when in a closed position. The upper half has an opening to receive a protrusion provided on the lower half of the insulator base to maintain the upper half of the insulator base along the grooves, providing static capacity between the electrode layer and the spark plug cables when voltage is applied across the spark plugs. A lead wire electrically connects the electrode layer to a microcomputer so as to analyze the burning condition based on the static capacity between the electrode layer and the spark plug cables. An electrical shield layer is embedded in the insulator base in the proximity of the electrode layer and connected to the internal combustion engine by way of a ground wire located at a side of the electrode layer remote from the grooves so as to electrically shield the electrical layer. An insulator sheet is embedded in the insulator base and located between the electrode layer and the electrical shield layer.