Abstract: A method of determining an air:fuel ratio based on information from an oxygen sensor exposed to exhaust gases of a combustion process, and related systems. A constant current is supplied to an oxygen sensor that has both an n-type sensing circuit and a p-type sensing circuit that share a common electrode. The currents in the respective sensing circuits is determined and a temperature value representative of a temperature of the oxygen sensor is determined. Then, an air:fuel ratio is determined based on the determined currents and the temperature value. The combustion process may then be controlled based on the air:fuel ratio. The air:fuel ratio may be determined, using the same oxygen sensor, across a range of air:fuel values in both the rich and lean regions; as such, the oxygen sensor may act as a wideband oxygen sensor.

Abstract: A method of determining an air:fuel ratio of a combustion process based on information from an oxygen sensor exposed to exhaust gases of the combustion process. A first value is determined indicative of the exhaust gas oxygen content, with the value being based on a resistance of an oxygen sensing portion of the oxygen sensor. A second value is determined indicative of a temperature of the oxygen sensor, which may be based on a resistance of a heater portion of the oxygen sensor. A third value is determined indicative of the air:fuel ratio as a function of the first and second values. Thus, the oxygen level data from the oxygen sensor may be temperature compensated so as to result in a more accurate estimate of the air:fuel ratio. The third value may then be used to control the combustion process, which may be associated with an internal combustion engine.

Abstract: A microchip oxygen sensor for sensing exhaust gases from a combustion process, and related methods. The microchip oxygen sensor includes a dielectric substrate and a heater pattern affixed to the substrate. A first electrode is affixed to the substrate and has a first plurality of fingers forming a first comb. A second electrode is affixed to the substrate and has a second plurality of fingers forming a second comb. The second electrode is disposed in spaced relation to the first electrode such that the first and second combs face each other. A semiconducting layer is disposed over the first and second electrodes so as form a physical semiconductor bridge between the first and second electrodes. The semiconducting layer comprises an n-type semiconducting material or a p-type semiconducting material. A porous dielectric protective layer, advantageously containing a catalytic precious metal, may cover the semiconducting layer.

Abstract: A method of making a sub-miniature “micro-chip” oxygen sensor is provided where multiple sensor elements are applied to a dielectric ceramic substrate consisting of a heater pattern, followed by a dielectric layer. Intermeshing electrodes are then applied either over the heater pattern/dielectric layers or on the opposite side of the substrate. The space between the intermeshing electrodes is filled with an n-type or p-type high temperature semiconductor which is covered by a porous protection layer. After singulation (dicing), the sensor element is assembled having conductors applied to the contact pads on the element and is packaged in an assembly for introduction to the exhaust stream of a combustion process. A large step-wise change in the resistance of the element takes place as a result of changes in oxygen content in the exhaust whereby one can determine if the exhaust is rich or lean for use in an engine management or combustion management systems for emissions control.

Abstract: A method of making a ceramic core is provided wherein the ceramic core is grit blasted using abrasive grit media particulates directed at the core through a preformed apertured mask or pattern to impart a controlled pattern of surface concavities to the core surface by impingement of the abrasive grit media thereon. Another method of making a ceramic casting core is provided wherein the ceramic core is formed in a molding die having a fugitive textured mask or a permanent textured insert positioned on the die surface to impart a controlled surface texture or roughness to the core surfaces.

Abstract: A green ceramic core or other article at elevated temperature is placed between a complaint member and a relatively rigid setter while the green core or article cools to a lower temperature. The compliant member can comprise a fluid pressurized compliant bladder or a compliant, non-rigid setter or facing layer thereon for contacting a side of the green core or article.