Method for forming layered heating element for glow plug

Abstract

A monolithic, multi-layer heating element forms the high temperature tip of a glow plug assembly. The heating element includes a conductive core which is surrounded by an insulator layer, which in turn supports a resistive layer. An optional conductive jacket can surround the resistive layer. These layered components are pre-formed in prior operations and then assembled one into the other to form a precursor structure. The precursor structure is transferred to a die, where it is compressed to form a so-called green part having dimensional attributes proportional to the finished heating element. The individual layers remain substantially intact, with some boundary layer mixing possible to enhance material-to-material bonding. The green part is sintered to bond to various materials together into an essentially solid mass. Various finishing operations may be required, following which the heating element is assembled to form a glow plug.

Dependencies are inferred from the claim text.