Abstract: A self-balancing type level gauge apparatus is disclosed, in which the change of a magnetic flux generated between coupling outer and inner magnet rings on the basis of a displacement between the coupling outer and inner magnet rings due to the displacement of a liquid level to be gauged is converted to an electrical signal which is used to gauge the liquid level to thereby reduce the mechanical portion which causes a mechanical friction so that the level gauge apparatus can be improved considerably in level gauging detection sensitivity.

Abstract: A liquid level meter having a first and second rotatable shaft mounted within a housing coaxially one within the other and coupled for relative rotation. A drum is mounted on one shaft and has a float suspended therefrom, for engagement with the liquid. Detecting means for sensing the torque on the drum is provided comprising an energy source and an energy receiver and a pair of relatively movable shield means located therebetween. One of the shield means is conjointly movable with one shaft and the other shield means is conjointly movable with the second shaft. Each of the shield means has spaced apertures aligned respectively with each other to permit selective passage of energy between the source and receive depending upon the degree of relative movement of the shield plates. A signal is produced in response to the sensing of energy variation which operates a motor coupled to one shaft to drive the same and consequently to rotate the other shaft in the direction of the torque exerted on the drum.