Glass sealed spark plug assembly

摘要

A spark plug includes an electrode which during assembly is inserted into a vertical bore of a ceramic insulator from beneath. The electrode has an expanded firing end protruding from the insulator bottom. Tabs at an upper end of the electrode are expanded inside the bore to engage the insulator, and this is done using a removable expanding tool inserted into the insulator. A conductive glass in granular form is poured into the bore and envelops the expanded upper end of the electrode. A sacrificial conductive push pin inserts into the upper bore over the glass granules. The sub-assembly is heated to melt the glass and the push pin is pressed down into the melted glass. Upon cooling, the glass within the insulator fuses forming a seal which further strengthens the flared engagement of the electrode to the insulator.