Sensor for measuring alcohol content of alcohol/gasoline fuel mixtures

摘要

An alcohol sensing device is provided for determination of the alcohol content within an alcohol/gasoline fuel mixture which is being provided for the operation of an internal combustion engine. The sensing device uses infrared spectrometry measuring techniques. The infrared sensing device determines the ratio of light absorption by the alcohol/gasoline mixture at two discrete wavelengths within the near- infrared spectrum. The two particular wavelengths of interest are preferably chosen so that at one of the infrared wavelengths, alcohol is strongly absorbing while the gasoline exhibits very little absorption, and at the second wavelength both the alcohol and the gasoline exhibit are essentially non- absorbing. An alternating current is used to switch the light beam between two power settings so as to vary the intensity of transmitted light at both wavelengths. The light beam is transmitted through the alcohol/gasoline fuel mixture so that the two discrete wavelengths traverse the same optical path. Two detectors are adjacently disposed so as to receive the emitted light from each wavelength after their transmission through the alcohol/gasoline fuel mixture. Once the signals corresponding to the two wavelengths are obtained, the ratio of the absorbances by the fuel mixture at both wavelengths is computed. From this ratio, and the temperature of the fuel mixture, the concentration of alcohol in the fuel is determined.