GB1130237A - Method and apparatus for sensing the level of contents in a container - Google Patents

Abstract

1,130,237. Measuring liquid level electrically. UNILEVER Ltd. June 26, 1967 [June 29, 1966], No.29179/66. Heading GiN. The level of material in a container is measured as the time taken for a probe 12 Fig. 1, to be lowered on a cable 9 from a predetermined position to the position where it contacts the material, a motor 4 driving a drum 7 carrying the cable at a constant speed by means of a belt 5. The cable 9 passes over a pulley 11, carried on a swinging arm 14 and supported by a spring 17, so that the probe 12 normally overcomes the spring pressure and a switch 22 is actuated by the arm 14. When the probe contacts the material surface, the spring retracts the arm and the switch 22 registers the end of the time measurement, the initiation of which is effected by a magnet 24 on the drum actuating a switch (23, Fig.2, not shown). The timing circuit includes a Miller integrator. The cable passes over a guide roller 10 mounted on a threaded spindle 13 which causes the cable to be laid evenly on the drum, end stops with microswitches (26, 27, Fig. 3, not shown) being provided to limit travel of the pulley 10 and the probe 12. Three such arrangements are connected by a selector switch (30, Fig. 5, not shown) to a timing means 28, and each one may be calibrated by measuring the time taken to touch the bottom of each bin.