Combination sparkplug and combustion process sensor

Abstract

To permit adjustment of the combination sparkplug-optical sensor for heat transfer upon operation of the sensor-sparkplug combination as a sparkplug, in accordance with known sparkplug technology, the insulator of the sparkplug is formed with a central opening in which a material is included which is electrically conductive and providing for controlled heat transfer, for example a packing or a mixture of aluminum oxide with a conductive powder, such as graphite, aluminum, or copper; or, alternatively, sheet metal elements may be located therein providing controlled radial engagement around a central glass rod forming the optical sensor and the inner wall of the opening and the insulator (FIG. 2); or, alternatively, axially resilient elements, such as a bellows-like corrugated metal element (FIG. 3) or a stack of spring disks (FIG. 4) may be positioned in the opening, axially biased by screwing the connecting terminal (10) into a tapped opening of the insulator. Heat transfer or transmission control is effected by introducing between metallic components of the combination and the glass rod a heat conductive mass (2) which fills the space between the glass rod and the metallic components over a predetermined length, in accordance with desired heat transfer characteristics.