Robert Boschgmbh

Rainer Schussler

Franz Rieger

Ernst Linder

Reinhard Latsch

Helmut Maurer

Heiko Gruner

Eckart Damson

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.

Combination sparkplug and combustion process sensor

To provide a pre-heated sensor which is capable of heating the sensing element exposed to gases to a temperature of above 400.degree. C. and preferably above 500.degree. C., at which temperature the sensor will be essentially immune to lead content in the gases, an elongated heating rod is placed within a sensor structure in which a solid electrolyte tube is held in position by a first stressed compression spring, the heating rod being formed with a radially projecting flange against which a second compression spring bears, concentrically located within the first, the heating rod itself comprising a long ceramic tube, preferably formed with two longitudinal bores to accept connecting wires to a thermocouple positioned at the end of the tube to sense the temperature of the sensing tube, surrounded by a first metallic tube forming an electrical connection to one terminal of a spiral heating wire which is wrapped around a fiberglass sleeve slipped over the metallic tube, connected to a second metallic tube outside of the fiberglass sleeve which, in turn, has yet another fiberglass sleeve slipped thereover, which is split in the region of the flange, to provide a sensing element in which all components are concentrically located within each other, and held in position by an end cap and in place by compression springs to permit assembly from the region of the end cap which, upon completion of the assembly, is secured in position, and compression-stressing the springs, thereby providing reliable connection and shock and vibration resistant seating of all components while permitting simple assembly under mass production conditions.

Internally, electrically heated electrochemical sensing element

An electrical heating element 35, 35' is located in a thin walled, closed metal tube or sleeve 37, 37' which is packed with a packing material 38, 38' of good heat conductive, insulating properties; the electrical heating element is a spirally wound resistance heater embedded in the insulating packing. A solid electrolyte body 11, 68 surrounds at least a portion of the thin walled metal sleeve and is positioned in heat exchange relation therewith. The solid electrolyte body may be a closed tube 11 or may be applied as a ring element 68 over the thin walled metal tube with an insulating material layer 66 interposed.

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Bietigheim, Germany

Rainer Schussler