Patent GB-1171391-A (GB)
Title: Apparatus for Indicating the Centre of Gravity of a Liquid in a Tank with Reference to a Datum Point
Inventor: LEVINS DAVE BAER
IPC: G06G7/70
Filed: 1967-01-06
Abstract: 1,171,391. Determining the centre of gravity of a quantity of liquid electrically. GENERAL ELECTRIC CO. Jan. 6, 1967 [Feb. 18, 1966], No. 891/67. Heading G1N. [Also in Division G4] The position of the centre of gravity of a quantity of liquid stored in a tank or tanks relative to a fixed datum is determined by apparatus which measures electrically the level of liquid in each tank, converting the corresponding signal to signals representative of the weight of the liquid and the moment of the liquid about the datum point and supplies the signals to a circuit producing a signal therefrom representative of the position of the centre of gravity of the liquid with respect to the datum point. Each tank 16,52, Fig. 1, is provided with a pair of liquid level sensors, e.g. potentiometers, 34, 35, the positions of whose sliders 56, 58 are controlled by the liquid level, connected in series with temperature compensating resistors 40, 41 to compensate for changes in density of the fuel with temperature. The outputs from the pair of potentiometers are combined after being fed through scaling resistors 45, 47 and 50, 51 respectively, resistors 45, 50 converting the signals into one representative of fuel weight and resistors 47, 51 converting the signals into one representative of fuel moment about the datum point. These signals are then fed to fuel weight indicating and centre of gravity computing and indicating circuits 12, 13 to which similar signals from other tanks are also fed. In circuit 12 the signals, indicative of individual fuel weights are indicated singly or in combination on a meter 81 whose pointer is driven by a servomotor 83 which also drives the sliders of identical potentiometers 76, 78, the output of potentiometer 76, indicative of fuel weight being fed back to the servomotor. The output of potentiometer 78 is fed to a potentiometer 85 in the circuit 13 where it is combined with a variable "dry" vehicle weight signal, dependent on the load of the vehicle, obtained from resistor 91 and a variably tapped resistor 94. The signals representative of the individual tank moments are combined in circuit 13 and added to a signal representative of "dry" vehicle moment (dependent on load), obtained from resistor 103 and variably tapped resistor 102, the combined signal being fed, via amplifier 105, to a servomotor 87 which drives the pointer of indicator 88 and the slider of the potentiometer 85. The output from this potentiometer, indicative of the position of the centre of gravity of the vehicle relative to the datum point, is fed back to the amplifier 105. The above measurements may be used to automatically cause fuel shifts between tanks to maintain the centre of gravity of the vehicle at a pre-set position or to trim an aircraft. The liquid level sensors take the form of two concentric cylinders 21, 22, Fig. 2, between which a series of magnetic reed switches 30 are arranged. There switches are closed by a magnetic float 32 to variably tap a resistance card 31, Fig. 3 (not shown), according to the liquid level.