Oxygen sensor based on optical detection
AssigneeGeneral Motors Corporation
InventorGlen A. Nyberg
Life of this patent
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Abstract
A gas sensing apparatus suitable for repeatedly sensing the partial pressure of a selected gas in a gaseous mixture is accomplished by employing optical detecting means. A sensing material having a light reflective surface reversibly reacts with a sensed gas in accordance with a temperature-sensed gas partial pressure relationship to cause a predictable change in reflectivity of the light reflective surface. The chemical reaction between the sensing material and sensed gas is reversible, therefore allowing quick, precise and repetitive sensed gas partial pressure determinations.
Claims10
An optical sensing apparatus, for repeatedly sensing the partial pressure of a selected gaseous component in a gas mixture, comprising:
- a film of heat responsive sensing material having a light reflective surface which reversibly reacts with a sensed gas in accordance with a temperature-sensed gas partial pressure relationship to cause a predictable change in reflectivity of the light reflective surface;
- temperature sensing means for detecting the temperature of the light reflective surface at two or more distinct locations on the light reflective surface;
- light source means for irradiating the light reflective surface, with a light beam from said light source means perpendicular to the light reflective surface;
- heat source means for providing a thermal gradient on the light reflective surface by means of a light beam transmitted from said heat source means perpendicular to the light reflective surface;
- and
- light detecting means for sensing reflection of the light irradiated on the light reflective surface from the light source means, said sensed reflection being transmitted perpendicular from the light reflective surface.
An optical oxygen sensing device for repeatedly sensing the oxygen partial pressure within automobile exhaust gases, comprising:
- a film of an oxidizable material having a light reflective surface which reversibly reacts with oxygen gas in accordance with a temperature-oxygen partial pressure relationship to form an oxide of said material on said light reflective surface, the oxidation of said material causes a predictable change in the reflectivity of the light reflective surface;
- temperature sensing means for sensing the temperature of the light reflective surface at two or more distinct positions on the light reflective surface;
- light source means for irradiating the light reflective surface;
- optical heat source means for providing heat to the light reflective surface;
- and
- light detecting means for sensing the reflectivity of the light reflective surface.
An optical oxygen sensing device, for highly precise, fast response oxygen partial pressure determinations within automobile exhaust gases for use within internal combustion engine control systems operating with lean air-to-fuel ratios, comprising:
- a film of an oxidizable material having a light reflective surface which reversibly reacts with oxygen gas in accordance with a temperature-oxygen partial pressure relationship to form an oxide of said material, the oxidation of said material causes a predictable change in the reflectivity of the light reflective surface;
- a translucent or transparent ceramic substrate, for providing structural support to the light reflective surface;
- temperature sensing means for sensing the temperature of the light reflective surface at two or more distinct locations on the light reflective surface;
- three way optical system comprising (1) light source means for irradiating the light reflective surface, (2) heat source means having a light beam for providing heat to the light reflective surface, and (3) light detecting means for sensing reflected light from the light reflective surface;
- and
- an optical fiber positioned to provide the means for transmission of the three light beams, the light source beam to the light reflective surface, the heat source to the light reflective surface, and the reflected light from the light reflective surface to the light detecting means.
Dependencies are inferred from the claim text.