Multi-capacitor fluid level sensor

Abstract

A tubular shaped fluid level or fluid volume sensor for mounting in a fluid storage vessel for sensing the level or volume of the fluid within the vessel which comprises: a first pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the capacitor elements being spaced from one another and shaped and arranged to generally define together the outer periphery of the tubular sensor; and a second pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the second pair of capacitor elements being positioned within and spaced from the first pair of capacitor elements and being spaced from one another and shaped and arranged to generally define together the inner periphery of the tubular sensor. Electrical insulating material located between the capacitor elements defining the other periphery of the sensor and the capaictor elements defining the inner periphery of the sensor for mounting the pairs of capacitor elements in fixed spaced relationship from one another and for positioning the elements so that each capacitive plate area thereof defines with a capacitive plate area of the next adjacent capacitor element a dielectric space therebetween so that the mounted capacitor elements together form four like dielectric spaces. Material of known constant dielectric value fills two of the dielectric spaces thereby forming with their respective space defining capacitive plate areas two capacitors of known fixed and substantially like capacitive value. The remaining two dielectric spaces are open to receive varying levels of fluid thereby forming with their respective capacitive plate areas, and the fluid within the spaces, two capacitors of variable capacitive value.