Patent GB-478502-A (GB)
Title: Improvements in or connected with gauges for indicating the quantity of liquid in petrol and other closed tanks
IPC: G01F23/16
Filed: 1936-04-18
Abstract: 478,502. Measuring cubical contents. LEIGH, W. April 18, 1936, No. 11138. [Classes 106 (i) and 106 (ii)] The quantity of liquid in a closed container is indicated by connecting the free air space to another vessel at higher or lower pressure so as to vary the pressure of the air in the container by a predetermined fixed amount, the amount of air so transferred being a measure of the liquid in the container. A high pressure container 50, Fig. 11, provided with a pressure gauge 9 is connected through a valve 52 to a petrol tank 56, which is also connected through valve 53 to a pressure gauge 10. Other petrol tanks may be selectively connected by branch pipes through similar valves 52, 53, each pair of valves having an actuating knob on an instrument panel. The actuation of these valves when a reading is required also energizes a solenoid 48 to lift ball valve 49. The gauge 10 is provided with a switch whereby the circuit of the solenoid 48 is broken when the pressure in the petrol tank is increased by a predetermined amount, say 1 lb. per sq. in. The quantity-indicating gauge 1 comprises a pressure gauge, the spindle 59 of which projects at 60 into a soft iron core 61 which carries an indicating pointer 3. The spindle 59 carries a twoleaf spring 64 with a steel friction disc 65. When any one of the tank switches is actuated, a solenoid 67 is energized, the core 61 is magnetized and the disc 65 attracted thereto, so that the pointer 3 indicates changes of pressure in the tank selected. To prevent more than one tank switch from being actuated simultaneously, the shaft 51 of a pair of valves 52, 53 carries a cam 69 having a locking hole 70, the cam being surrounded by a framework comprising a pair of sliding rods 72, Fig. 8. When a tank switch is in the " test " position, the frame is pushed towards .the left, and locking bolts 75 enter the holes 70 in the cams associated with the remaining switches, so that these cannot be moved. The tank gauge is provided with concentric scales, each corresponding to one tank, and the scale appropriate to the tank being tested is automatically illuminated by the turning of the tank switch. Alternatively, the vessel 50 may be evacuated, in which case a predetermined reduction of pressure is obtained in the tanks. When air under pressure is used, it may be supplied to the vessel 50 by a pump electrically driven under control of the switch which places the apparatus under the " test " conditions, in conjunction with a second switch actuated by the pressure gauge 9. In a modification, Fig. 1, means are provided to correct for variation in barometric pressure during the reading of the gauge, and for difference in temperature between the air in the high pressure container and the petrol tank. The pressure gauge 9 of the high-pressure container engages a toothed gear-wheel 12 on the shaft 22, Fig. 5, carrying one of the planet wheels 16 of a differential gear. The other planet wheel 16 is similarly engaged by a barometer gauge, and the sun-wheel 20 (13 in Fig. 1) is connected through a gear-wheel 14 with a planet wheel 15 of another differential gear similar to that of Fig. 5. The other planet wheel of this gear is subject to the effect of temperature differences between the air container and the petrol tank, transmitted through another differential gear No. 4, rod 41, link 29, and sector 28. Gearwheel 36 actuates the pointer indicating the quantity of petrol. The pressure gauge 10 on the tank is also corrected for barometer variations by means of differential gear No. 3 similar to No. 1.