Patent GB-252837-A (GB)
Title: Electric indicating means particularly adapted to indicating systems for motor vehicles
IPC: G01F23/64
Filed: 1925-03-31
Abstract: .252,837. Haddan, A. J. H., (Auto-Meter Co., Inc.). March 31, 1925. Indicators, electric.-Electric means for indicating the quantity of liquid in a number of receptacles, and particularly adapted for use on motor vehicles for indicating the quantity of fuel in the storage tank, oil in the crank case and cooling medium in the radiator, and for automatically operating a signal when the temperature of the cooling medium rises above a predetermined limit, comprises a calibrated drum 33 arranged within a non-magnetic casing, and carrying a split ring 44 of polarized material adapted to be influenced by magnetic forces generated in two coils 38, 39, secured to the casing in such a way that the ring engages within their cores. One terminal of each coil is connected to the positive side of an electric battery. The other coil terminals are connected to the negative side -by grounding, the circuit of coil 38 including a fixed resistance 42 and that of coil 39 a variable resistance controlled by the quantity of liquid in one of a number of tanks or by the temperature of the cooling medium in the radiator. The variable magnetic force generated by coil 39 exerts a variable repelling force on the magnet in the direction of one of its poles and the fixed magnetic force generated by coil 38 exerts an independent and opposed repelling force in the direction of the other pole so that the ring 44 is caused to move, the calibrations being visible through a window 51 having an indicator rib 53. To enable the instrument to indicate the conditions of various apparatus when required it is connected in open circuit with the various variable resistances, contact makers 70, 71, associated with a push button 73 being provided for closing each circuit for obtaining a reading. Additional contact makers 77, 79, close the circuit of a lamp L for illuminating the instrument when a reading is taken. A resistance controlling device for connection to the lower portion of the radiator or for mounting in the crank case comprises a tubular carrier 60, Fig. 12, electrically connected to the battery by grounding and having a series of superposed seats 63 of conducting material for ball members 64 adapted to be successively lifted by a rise of the liquid level and connecting terminals 65, 66, to cut out an increasing amount of resistance 68 included in the circuit of coil 39. For indicating the quantity of fuel in the storage tank T, Fig. 16, a number of resistances 92 may be employed connected in series with U-shaped conductor plates 93 mounted upon an insulator bar 94 and carrying loosely secured yoke-shaped wire contacts 96 adapted to contact with a surrounding non-magnetizable conductor tube 98 by means of a magnet-carrying float 102, whereby a varying amount of resistance is connected to the circuit of coil 39 by a conductor 100 depending upon the position of the float. The tube 98 and float are enclosed in a housing 105<1> having a slow flow connection with the liquid in the tank through ports 107. The length of the plates 93 is so varied as to compensate for variations in the area of the tank at different levels. A thermometric resistance controlling device may comprise a mercury thermometer 84, Fig. 13, adapted to be suspended from the filler opening of the radiator and having spaced contacts 87 connected to tappings from a resistance 83. A further contact 89 opposite to the uppermost contact 87 is provided for closing the lamp circuit automatically when the mercury rises to the top of the tube. In a modification, both coils 38, 39, are connected to the variable resistance, the instrument being actuated by variations in the value of both of the magnetic forces generated by the coils.