Patent GB-606808-A (GB)
Title: Improvements in or relating to telemetering devices
IPC: G01F23/26
Filed: 1945-06-06
Abstract: 606,808. Telemetering systems. LIQUIDOMETER CORPORATION. June 6, 1945, No. 14222. Convention date, Dec. 11, 1944. [Class 40 (i)] In a remote liquid level measuring system of the type in which liquid level variations in a tank cause variations in the valve of a transmitter capacitor, the system is arranged to be adjustable for fluids of varying dielectric constant by ganging a dielectric element which can be inserted to a variable extent between the plates of the transmitter capacitor with a variable capacitor shunted across the latter, the arrangement being such that rotation of the two produces no change in the " empty " capacitance, but produces a change in the " full " capacitance, whereby the " full to empty " capacitance change can be maintained constant for different liquids by adjusting the ganged elements. Fig. 1 shows such an arrangement in which the paralleled capacitative path comprises a trimmer condenser 31, a variable condenser 30 whose rotor is mounted on the shaft 90 which also carries a dielectric member 29, which may be swung between the plates of the transmitter condenser through a slot 28, the transmitter condenser itself and a temperature compensating condenser placed in the tank liquid and having a bimetallic electrode which moves in accordance with temperature variations. The capacitance changes in the transmitter condenser and in condenser 30 when shaft 90 is rotated, are arranged to be equal and opposite when the tank is empty so that the " empty " capacity is determined solely by trimmer 31, which is set accordingly. When the tank is full, however, the changes in transmitter capacitance caused by the rotation of shaft 90 are less so that they no longer cancel those caused by condenser 30, and the shaft may be rotated to adjust the " full " capacity. Dial 92 is calibrated in dielectric constants, and is set when the full capacitance has been adjusted so that pointer 91 is opposite a point on the scale corresponding to the dielectric constant of the liquid in the tank. The system being adjusted for any other fuel by rotating the pointer to the appropriate point on the dial.. Fig. 3 shows a modification of the transmitter condenser shown in Fig. 1 in which the variation in capacitance is obtained by rotating a dielectric element 99 about an axis 100, a vertical slot 98 being provided in the outer electrode so that the capacitance varies with the rotation of element 99. In the Specification as open to inspection under Sect. 91, Figs. 2-6 (Cancelled) (not shown), show various ways in which the normally concentric electrodes of a transmitter capacitor for a fuel tank as shown in Fig. 1 (Cancelled), may be displaced to independently adjust the " full " and " empty '' capacitances, while Fig. 7 (Cancelled) shows an arrangement in which adjustments are made by inserting suitably configured rods of a material having a suitable dielectric constant. Fig. 8 (Cancelled) shows an arrangement in which the position of an extension 24 of the outer electrode may be adjusted to vary the capacitance in the desired manner. The desired effect may also be obtained by distorting one of the electrodes. This subject-matter does not appear in the Specification as accepted.