GB795189A - Improvements relating to capacitors for use in liquid level gauges - Google Patents

Abstract

795,189. Electric tests. SIMMONDS AEROCESSORIES, Ltd. Sept. 5, 1955 [Sept. 6, 1954], No. 25853/54. Class 37. A liquid contents gauge capacitor comprises a support of dielectric sheet material and a plurality of thin narrow ribbons of conducting material pro viding the plates of the capacitor. The ribbons run all in the same direction and are secured to the support along their length. The thickness of each ribbon is of the order of a few thousandth of an inch or less. In Fig. 1, thin narrow conductive ribbons 5 run the length of an insulating strip 2 bonded to an insulating strip 3. The ribbons 5 are connected to a coaxial cable connector 6 and tabs 4 on strip 3 secure the assembly on to a wall of a flexible fuel tank for an aircraft. Screening wire may be wound around the strip, Figs. 2 and 3 (not shown), or strip 2 may be threaded into a metal cage comprising transverse strips alternately above and below strip 2, Fig. 4 (not shown). Fig. 5 shows a capacitor strip 20 (e.g. as in Fig. 1), wound around a flexible insulating tube 21 which surrounds a second tube 22. After assembly in a fuel tank a setting resin may be introduced between the tubes 21, 22 to rigidify the assembly. In a modification of Fig. 5 the capacitor strip 20 is wound on the inside surface of the inner tube 22, Fig. 6 (not shown). A further example, Fig. 7, utilizes a capacitor strip 31 mounted taut within a metal screening tube 32 by spacer clips 33. The top of the tube 32 carries a cap moulding 34 with a coaxial cable connector 35. In Fig. 8 a capacitor strip 40 is wound on the outside of a paper-base tube 41 having longitudinal spring ribs 42 which space the strip 40 slightly from the tube 41. In an alternative form of this unit the capacitor strip 40 is wound inside a paper-base tube. The embodiment illustrated in Fig. 9 comprises a capacitor strip 50 wrapped about a paper base tube 51 so that the conductive ribbons 52 run parallel to the tube axis. A collector ring 54 is provided at the upper end of the tube 51. The capacitor strip could alternatively be wrapped within the tube. A second tube may be arranged within tube 51 and the assembly rigidified by a setting resin. The relation between capacitance and volume may be made linear by varying the pitch in the case of wound units (e.g. as in Fig. 8) or by varying the width of the capacitor strip (e.g. as shown in Fig. 9).