US1737750A - Oscillating circuit for train-control systems - Google Patents

Description

1929? T. E. QLARK El AL 1,737,750

OSCILLATING CIRCUIT FOR TRAIN CONTROL SYSTEMS Filed 001:. 23, 1925 INVENTORS Patented Dec. 3, 1929 UNITED STATES PTENT; OFFICE THOMAS E. CLARK AND JAMES E. CLARK, or nnTRorT, MIonIGAn, ASSIGNORS To con- Trnuons TRAIN CONTROL CORPORATION, OF nRTnorT, MICHIGAN, A CORPORATION 01? MICHIGAN OSOILLATING CIRCUIT FOR TRAIN-CONTROL SYSTEMS Application filed October 23, 1925. Serial No. 64,353.

While testing the train control installation shown in our co-pending application Serial Number 31,633, filed May 20, 1925, we found that the conductivity of the ballast between 5 the rails and the resistance and the impedance of the rails were serious factors and that the electromagnetic wave energy propagated in the track rails waseflective for limited distances only, depending somewhat on the wave lengths; We experimented with currents having wave lengths of from One thousand to thirty thousand meters and tried out vacuum tubes of from 5 to 250 watts capacity. These tubes were used as transmitting oscillators, in some cases with transformers of alternating signal currents, and in other tests, using storage batteries and rotary dynamotors.

VVe' found that the electrical conditions in the rails were stabilized by connecting a loading condenser across between the rails at a distance from the point where the current transmitting mechanism was connected to the rails, these rails being divided into blocks and the transmitting or propagating devices for the high-frequency currents being connected to the exit ends of the blocks. With this loading condenser connected across between the rails, we found that the variations of dissipation of current due to wet, dry or frozen ballast between the condenser and the point of connection 'of the propagating device were not so marked.

We also found that when a loop collector coil mounted on a locomotive or other moving vehicle, is placed in this field of force and adjacent to but spaced apart from one of the rails, and this coil is tuned to resonance with the electr-o-magnetic wave'energy in the rails, that a proper instrument such as a mille-am- )eremeter' connected in this collector circuit indicated an appreciable and effective current therein.

We also found that as the locomotive travelstoward the exit end of the block, the collector coil circuits get out of tune with the track current circuits, due to the change of wave length of the current propa ated in the rails, because of the change in the inductance of the track circuit, which resulted from the change in length of the oscillating circuit including the track rails. We discovered that this change in wave length could be rendered negligible by constructing the loading coil; of the current transmitting mechanism with a large number of inductance turns so as to stabilize the wave lengths in the circuit of the track rails, including the locomotive axle moving thereon, and we found that the collector coil and its circuit, when adjusted through a proper variable condenser therein, could then be easily made to respond to the electro-magnetic lines of force or flux created by the locomotive axle completing the oscillating track circuit.

Our invention, therefore, consists of means for propagating electro-rnagnetic wave energy in the rails of a railway track, the propagating device being so constructed that the wave lengths of these currents will not be unduly varied by a locomotive as it moves along the rails of the energized section of tree It further consists in the details ofconstruction illustrated in the accompanying drawing and particularly pointed out in the claims. 7

'In said prior application we have explained the transformer for propagating high-frequency electro-magnetic waves in the track and how collector coils mounted on the locomotives and tuned to these waves picked up currents which so affected certain instrumentalities on the locomotives as to control their operation. This transformer comprises a vacuum tube 38 having a plate 45, a grid 42 and a filament 37. This filament is heated by the battery 13 whenever its circuit is closed, which occurs when the track section between the insulations 3 in the rails 1 and 2 and the condenser 20, is occupied by a train T, shortcircuiting the relay 7 normally energized by battery 8, which permits its armature a to close the circuit from the battery over wire 12, lilament37, wire 14, adjustable resistance 39, wire 10, armature 7 and wire 11. The main oscillating circuit consists of the wires 15 and 10, the resistance 39, wire 14:,filament 37, across the tube to the plate 45', wire 4:8, coil 4:7 and wire 46 to the battery 36'. The frequencies and wave lengths are controlled by the adjustable con-denser 50 which shunts the plate coil 47. This battery 36 is usually termed the B battery and is preferably of 350 volts. Any other proper source of current may be employed.

The loading coil 52 connects to the wires 5 and 6, which connect the relay 7 to the rails, by means of wires 32 and 33, a condenser being provided to prevent the passage of direct signal currents and the short circuiting of the track circuit. This coil 52 and its con necting wires, the rails 1 and 2 of the section between the wires 5 and 6 and the condenser 20, and this condenser 20, constitute the output oscillating circuit. The electro-magnetic waves of this circuit may be used to affect instrumentalities on the locomotive passing over this track section which are tuned thereto, at which time the leading or pilot axle of the locomotive and the wheels there-on affect these wave lengths to some extent.

The inductance of the coil 52 and its wires, of the condensers-35 and 20 and of the axle and wheels remains constant, but that of the rails of the section, which may be two hun dred or more feet in length, is reduced as the locomotive moves from the condenser 2O to-- ward the insulations 3. This change was found suiiicient to so vary the electro-magnetic wave lengths in this oscillating circuit that instrumentalities on the locomotive which were tuned to the wave lengths which were present when the locomotive was at the condenser 20 were not affected when the locomotive reached the exit end of the section. I I The loading coil can easily be wound to have from 40 to 50 milihenrys of inductance and when a condenser 20 of fairly large ca p'acit-y is employed, the change in wave lengths of the currents in this oscillating circuit need not be more than 50 meters, or not morethan one per cent. If the collector circuits onthelocomotive are tuned to the wave lengths which are present when the leading axle of the locomotive is at the middle point of the controlled track section, these collector coils will respond to the electro-magnetic waves throughout the length of such section, especially as such instrumentalities respond to currents whose wave lengths vary two or even more per cent.

The details of construction of the mechanism described and the proportions of the parts may all be changed by those skilled in the art" without departing from the spirit of our invention, as set forth in the following claims.

We claim 1. Means for controlling the operation of railway trains comprising a track divided into control sections, a condenser connecting the rails at one end of each section, and means connected to the rails at the opposite end of such section adapted to propagate high-frequency electro-magnetie waves therein, said means embodying a loading coil connected directly to the rails and having a greater inductance than the rails of said section.

2. Means for controlling the operation of railway trains comprising a trackdivided into control sections, and means connected to the rails at one end of each section adapted to propagate high-frequency electro-magnetic waves therein of proper lengths to atfeet instrumentalities 'on' locomotives passing over such sections, said means embodying a coil of such high inductance that the lengths of the waves in the rails of such section will not be varied sufficiently by the shortening of the track circuit when the locomotive passes over such sections as to pass out of the range of the instrumentalities on such locomotive.

8. Means for controlling the operation of railway trains comprising a track divided into control sections, and a transformerconnected to the rails at one end of each control section adapted to propagate high-frequency electromagnetic waves therein of proper wave lengths to affect instrumentalities on locomotives passing over such sections, said means embodying an inductance coil of three Widings comprising a grid coil, a plate coil and a loading coil, all in resonance with each other, the loading coil being of such high inductance that the lengths of the waves in the rails of such section will not be varied suiliciently by the shortening of the track circuit when the locomotive passes over such sections as to pass out of the range of the instrumentalities on such locomotive.

4. Means for controlling the operation of railway trains comprising a track divided into control sections, and means connected to the rails at the opposite end of such section adapted to propagate high-frequency electromagnetic waves therein, said means embodying a loading coil connected directly to the rails and having a greater inductance than the rails of said section.

5. Means for controlling the operation of railway trains comprising a track divided into control sections, and means connected to the rails at one end ofea'ch section adapted to propagate high-frequency electro-magnetic waves therein of proper lengths to affeet instrumentalities on locomotives passing over such sections, said means embodying means of such high inductance that the lengths of the waves in the rails of such section will not be varied sufliciently by the shortening of the track circuit when the locomotive passes over such sections as to pass out of the range of the instrumentalities on such locomotive.

THOMAS E. CLARK.

JAMES E. CLARK.

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