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Title: Capacitive fuel composition sensor with slow oscillator and high speed switch

Abstract

A fuel composition sensor is described for a fuel mixture in a fuel supply line for a combustion engine wherein the fuel mixture comprises two fuels of different dielectric constants in unknown relative concentrations, at least one of the fuels being electrically conductive, the sensor comprising, in combination: a sensor capacitor in the fuel line adapted for fuel flow therethrough so that the fuel mixture provided to the engine comprises a dielectric which determines the capacitance thereof but also comprises a capacitor shorting electrical conductance; a reference capacitor of constant capacitance in series with the sensor capacitor to form therewith a voltage divider having an output junction; and circuit means comprising a square wave oscillator with an output high speed switching MOSFET connected in series with a resistance across an electric power supply, the reference and coupling capacitors being connected in series across the MOSFET with the coupling capacitor having an electrode connected to the junction of the resistance and MOSFET, the circuit means being effective to repetitively produce, at a comparatively low frequency, a predetermined fast voltage change across the series combination of the reference and sensor capacitors to produce a corresponding voltage change at the output junction comprisingmore » an initial voltage change essentially proportional to the capacitance ratio of the sensor and reference capacitors followed by an opposite voltage change due to leakage current through the fuel mixture, whereby the initial voltage change indicates the fuel composition.« less

Inventors:
; ; ; ;
Publication Date:
OSTI Identifier:
6329887
Patent Number(s):
US 5231358; A
Application Number:
PPN: US 7-809618
Assignee:
General Motors Corp., Detroit, MI (United States); National Semiconductor Corp., Santa Clara, CA (United States)
Resource Type:
Patent
Resource Relation:
Patent File Date: 18 Dec 1991
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; CONTROL EQUIPMENT; DESIGN; DUAL-FUEL ENGINES; LIQUID FUELS; CHEMICAL COMPOSITION; CONTROL; DIELECTRIC PROPERTIES; ELECTRIC POTENTIAL; FUEL SUPPLIES; MIXING; MIXTURES; MOSFET; OPERATION; PROBES; DISPERSIONS; ELECTRICAL PROPERTIES; ENERGY SUPPLIES; ENGINES; EQUIPMENT; FIELD EFFECT TRANSISTORS; FUELS; HEAT ENGINES; INTERNAL COMBUSTION ENGINES; MOS TRANSISTORS; PHYSICAL PROPERTIES; SEMICONDUCTOR DEVICES; TRANSISTORS; 330100* - Internal Combustion Engines

Citation Formats

Kapsovathis, N S, Wright, C D, Sanders, S P, Johnson, N M, and Chun, F C. Capacitive fuel composition sensor with slow oscillator and high speed switch. United States: N. p., 1993. Web.
Kapsovathis, N S, Wright, C D, Sanders, S P, Johnson, N M, & Chun, F C. Capacitive fuel composition sensor with slow oscillator and high speed switch. United States.
Kapsovathis, N S, Wright, C D, Sanders, S P, Johnson, N M, and Chun, F C. Tue . "Capacitive fuel composition sensor with slow oscillator and high speed switch". United States.
@article{osti_6329887,
title = {Capacitive fuel composition sensor with slow oscillator and high speed switch},
author = {Kapsovathis, N S and Wright, C D and Sanders, S P and Johnson, N M and Chun, F C},
abstractNote = {A fuel composition sensor is described for a fuel mixture in a fuel supply line for a combustion engine wherein the fuel mixture comprises two fuels of different dielectric constants in unknown relative concentrations, at least one of the fuels being electrically conductive, the sensor comprising, in combination: a sensor capacitor in the fuel line adapted for fuel flow therethrough so that the fuel mixture provided to the engine comprises a dielectric which determines the capacitance thereof but also comprises a capacitor shorting electrical conductance; a reference capacitor of constant capacitance in series with the sensor capacitor to form therewith a voltage divider having an output junction; and circuit means comprising a square wave oscillator with an output high speed switching MOSFET connected in series with a resistance across an electric power supply, the reference and coupling capacitors being connected in series across the MOSFET with the coupling capacitor having an electrode connected to the junction of the resistance and MOSFET, the circuit means being effective to repetitively produce, at a comparatively low frequency, a predetermined fast voltage change across the series combination of the reference and sensor capacitors to produce a corresponding voltage change at the output junction comprising an initial voltage change essentially proportional to the capacitance ratio of the sensor and reference capacitors followed by an opposite voltage change due to leakage current through the fuel mixture, whereby the initial voltage change indicates the fuel composition.},
doi = {},
url = {https://www.osti.gov/biblio/6329887}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1993},
month = {7}
}