Importance

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Abstract

An engine control system for operating an internal combustion engine with any mixture of alcohol and gasoline. The control system includes an air/fuel ratio control system providing a desired fuel charge in relation to the alcohol and gasoline content of the fuel which is indicated by an optical sensor. In one embodiment, the optical sensor includes a hemispherical lens having hemispherical recesses formed through the lens base equidistant from the lens plane of symmetry. A light emitting diode positioned in one recess irradiates substantially the entire 2 .pi. steradian outer surface of the hemispherical lens. A portion of the transmitted light is reflected from substantially the entire hemispherical lens and substantially focused on a photodetector positioned in the other recess. Emitter and detector are substantially positioned at conjugate focii of the lens which provides substantially a 2 .pi. steradian collection aperture. The amount of transmitted light reflected is related to the index of refraction of the surrounding fuel mixture thereby providing a measurement of fuel composition.

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First Claim