US2000166A - Railway signal system - Google Patents

Description

May 7, 1935.

L. ESPENSCHIED RAILWAY SIGN-AL SYSTEM Filed Aug. 241, 1926 3 Sheets-Sheet l INVENTOR zzovo 3BPEIV6CH/ED ATTORNEY 1935. L. ESPENSCHIED 2,000,166

RAILWAY SIGNAL SYSTEM Filed Aug. 24, 1926 3 Sheets-Sheet 2 /2 H I l INVENTOR Z; 0 ya ESPf/VS 6/1/50 mrw ATTORNEY May 1935. ESPENSCHIED 2,000,166

RAILWAY S IGNAL SYSTEM Filed Aug. 2 1926' 3 Sheets Sheet 3 INVENTOR 14 m0 zis f/vscflmo ATTORNEY Patented May 7, 1935 UNITED STATES v r l, 1 0

' RAILWAY SIGNAL SYSTEM i. Lloyd Espenschied, Hollis, N. Y. 7 Application August 24, 1926, SerialNo. 1211,14; '1 Claims; (01. 246-L63) This invention relates to railway signal and automatic train controlisystems, and more particularly to the means employed for transmitting the signal indications between the wayside I and the train.

.In abroad sense, the present invention em-' sidecircuit, (2) the transmission of the power.

backagain to the train after having been controlled in accordance with traific conditions ahead and 3) the actuation of the signal device on the train by the return transmission. The earlier embodiment provided means for discriminating between the outgoing and the return transmission and of thereby insuring that the energy which is effective in operating the signal device is that which has been subjected to wayside control in accordance with traflic conditions.

The system of the present invention from that .disclosed in the earlier patent in sev-' eral respects but particularly in the method employed 'for discriminating between the exciting energy sent into the wayside system and the signaling energy returned to the train. In accordance with the present invention two wayside circuits are set up, one for the outgoing .and' the other for the return transmission and are so superimposed one upon. the other, as to enable the same wayside inductors to be employed for both circuits. Discrimination between these two circuits is accomplished by disposing them in a mutually balanced manner. V r

The invention includes the application .of these features to both continuous and discontinuous control systems. In the continuous control type of system, the. wayside inductors which receive the energy from and return it'to the train, extend along the wayside moreor less coincident with the block sections' The track rails themselves are preferably utilized asthe wayside inductors. In the discontinuous control type of system the wayside inductor elements are localized coils. An object of the invention will therefore be appreciated tobethat of providing an inductive type of system employing an inert wayside circuit and one capable of being employed for either intermittent or continuous train control. Further objects, such as those of obtaining more than'two signal indiffers. nated iron core and is so mountedonthe train dications and o providing a system which opera ates in accordance with the closed circuit principle, will be evident from the illustrative em I bod-iments shown in the accompanying drawin'gsinwhichz- Figures :1 and 2 show. the application of invention in an intermittent} control type of system, Figure l being the trainecarried portion, and Figure 2 a schematicshowing of the wayside portion; of the system. i Q a Figure 3 shows the application of my invention to a continuous control type of system; the wayside system being shown in asimplifled Figure 4 shows a wayside system' similar to that shown: in Figure 3, superimposed upon or- 15 dinary block signal" track circuits.

Referring to-Figure 1, alternating-current energy is generated aboard the train by gene a or I, The energy is passed through transformer 2, through conductors 3,1, and 5, 6 to-the train 20 inductor coils I and 8. These coils may b tuned individually to the frequency of the generator by means of. condensers 9 and I0. Each-of the coils l and 8 embracesja-n inverted U-shaped lamias to pass over and coaet inductively with complementary coils disposed in the wayside' The wayside'coils, designated H and 12, in Figurel2, are likewise provided with U-shaped laminated ironcores. The wayside cores are made 3;) of large. size because they are intended in themselves, without their coils, to afiect the traincarried circuit, as will be described. When the train passesthe wayside control point, train 'coil 1 links magnetically with wayside-coil H and train-0011 8 with wayside coil 12,. The wayside-coils maybe tuned individuallyby densers l3 and M. The wayside coils are con-- neeted together in the manner indicated and their'circuit is extended by means of conductors 41) I5, 16' thrQ gh the contacts of relays 11,18 to transformer l9.- I v 1 The two train coils and the two wayside coils are so connected in their respective circuits current from generator I flowing through co'iis l and .8 induces current'in coils .H .and J2 which are connected in series aiding relation with re. spect to each other in circuit 15, L6, This current flows through conductors l5 and IGJ'and' through the primary winding (1 (which is icen- 5.0 ter-tapped) of transformer [9.1 The current so established induces an E. M. F, in the secondary winding of transformer 49. Said winding 1) sends current through a c:ircuityvjiriich' may be traced as :follows, the relative polarity PATENT "ow s being that which obtains at some one instant: Conductor 20 to the center tap'of the primary a of transformer l9, through the two halves of the transformer winding in mutually parallel opposing relation, thence in parallel along conductors !5 and I6, through coils H and i2, mutually in parallel, and back on conductor 2| to secondarywinding b.

Thus the wayside circuit receives an excitation in'one sense, asthrough the two coils H, l2

. connected in series and poled to be aiding around the circuit l5, I6, and transmits current back in another sense through the two sides, !5[

and I6, of the circuit in parallel connected by a third conductor 2|.

train. The return-transmission wayside circuit,

(traced by 26, i5 and |6.i n parallel, H and [2 in parallel, 2i and secondary b), is therefore bal ahead and non -interfering with respect to the l mutually aiding with respect to and cause current to flow in a circuit superposed upon and balanced with'respect to circuit 5, 6, the flow being at some one instant as'follows: Along conductors 5, 6 :in parallel; 3;4 in parallel to the secondary of the current supply transform er 2; through the two'halves ofthis'winding in parallel opposing relationto the center tap and thence along conductor 22;through winding 23' of the receiving relay 23,'and back on conductor 24 to the point midway betweencoils 1 and 8., By passing the received current through the train inductor coils in this balanced'rna'nner, it is impressed upon the actuating winding of the receiving relay to the exclusionof the outgoing current; be of the A. C. excited type, current from the generator being supplied to the magnetizing windings through conductors. 25, 26.

With respect to the use of the two pairs of inductors simultaneouslyfor the establishment of two distinct transmission paths, one for transmittingthe exciting current to the wayside signal location and the other for selectively transmitting the signal indicating currents back tothe train} the-following further elucidation may be useful: The train-carried inductors 1, ,8 operate'in'series in circuit 5, 6 to deliver power to wayside inductors 1!,12. The latter in turn operate in'series to transmit the'power over oncuit I5, Hi, to the primary a of transformer IS. The return'transmission path may be regarded as originating in secondary winding 1), and extends along 26, along {5, [6' taken in parallel,

through wayside inductors ll, 12 taken in parallel, along 2! back to the secondary 12.. Thus the wayside inductors operate in parallel for the return transmission to induce currents in train inductors land '8 which fiowcorrespondingly in parallel along conductors 5, 6, along 3, 4, traverse conductor 22; relay winding 23 and thence over conductor ll ba'ck to the inductors. Thus the The wayside inductor coils' are thus energized in a mutually paralle1 and opposite sense for retransmission back to the e The receiving relay is illustrated to tively transmit back to the train the energy carrying the signal indications. The way in which the signal indications are actually impressed uponand taken from the return transmission path will now be described. The'basis of signaling which is preferred for this discontinuous type of system is one wherein the wayside control elements are made to tend normally to give a stop indication, and wherein the giving of a'caution or a clear indication is accomplished by overcoming the' stop" indicationand substituting for it'the safer indication. Accordingly, there is provided in the present invention a tripping means which gives a stop indicatimrunless positively displaced by a caution or clear indication. The tripping means comprises a balanced circuit centered about the 3-winding balancing transformer, illustrated as included within the dotted rectangle 39. The B-Winding balancing transform er is of the type commonly known in telephone engineering as ahybrid 'coil and need not be described in detail. The circuit includes on one side of the balance both of the train coils I and 8 taken in series and aiding in their effects and on the other side a balancing coil or coils 21, 28. In cases wherecondensers 9, 10 are employed balancing condenser 29 is included on the balancing side. -The inductance of ,coils 27--2S is made equal to the combined series connected inductance of coils land 8 when over the cores of wayside coils l I. and 13, with the circuit E5-I6 open. e

Under this condition the circuit is balanced so that no current is induced in the middle winding of thehybrid coil, the electromotive forces induced in this winding from the two halves of'the primary winding being equal and pr posed. When the j circuit is unbalanced these forces are unequal and a' resultant current flows in a relay 3! connected in circuit with the middle winding of the hybrid coil.

With the wayside circuit open, as is the case for the stop condition, the circuit for including current in the circuit of relay 3! tends to become balanced as'the train coils pass over the wayside inductor cores. As a result, the currentin relay 31 is greatly reduced and the relay contacts open. The train signal circuits are arranged so that this gives a stop indication. A stopindication will then also be given in case of failure ofrthe source of current When the trainis between control points the circuit is unbalancedand relay 3! is held closed by ourrent'transmitted from the generator I through the balancing transformer rectangle 3Q.

Thus it will be seen that one indication, the stop indication, is passed to the train merely by the action of the cores of Wayside coils II and E2 in unbalancing atrain-carried circuit. In' ;actual operation this action comes into play upon'the opening of circuit l -l6 by the re-' indicated by the lease :of relayfl; Relays l1 and 18 will be understood to be operated from. the track circuit of the usual type of block signal system.

The safety indication is given when the wayside circuit is in the condition illustrated in Figure 2. The circuit .is'so arranged that when the train passes over the wayside control point therelative instantaneous polarity of the energy transmitted back to the; train, .anth which enters winding 23 of the receiving relay, will be such "as to move. the armature of the receiving relay-to, say, the left contact. This causes the. actuation of relay-32 which 'in'turn is made todisplay a clear indication 'throughthe' ap-,.

propriate local circuit arrangements. These ar-Q energized and functions to give-the. caution signal. It will be understood that the signal indications described above may be employed in conjunction with well known'types. of-speed control devices to control automatically the speed of the train.

The wayside signaling relaycontacts are illustrated connected in the wayside circuit ate. point which is common to both of the two superimposed transmission circuits, one receiving from the train and the other transmitting to the, train. They could as well be placed in the circuit at 20, 21, where theywould be confined to the path transmitting to the train, and the transformer l9 would receive power from the train irrespective of the wayside relays. I a

It is desirable to note also that wayside transg former. I9, constitutes a means for terminating the power-supply transmission channel and for turning it back upon itself over a superimposed balanced channel transmitting back to the train. By thus acting to interconnect two channels which otherwise are balanced one against the other, the transformer is really a means for effecting a total unbalance between the two chan nels in question, and in turn an unbalance between the transmitting and the receiving circuits upon the train. The unbalancing action is thrown in or out by relay l1, and the relative sense or polarity of the unbalance is controlled by relay I8.

This constitutes. another way of looking upon the modus operandi of the present type of system, including the continuous as well as the intermittent control system.

Referring now' to the continuous control sys-' tem of Figure 3; alternating-current energy from generator I is transmitted through transformer 2, along conductors 3, 4 and 5, 6 to the traincarried inductors l, 8. These coils are disposed on the train in proximity to the track rails H,

J H for the purpose of inducing current therein.

current flows longitudinally along the rails to the end of the block section, and returnsover a third conductor 2| provided along "theright-ofway, as by being carried on the'wayside pole line. The transmission path may be traced gas follows: along rails ll, I 2 in parallelpalongcone ductors, I 5, l6 in parallel; through the two halves of the'winding of transformer l9v non-induc-v tively, to the center tap; along conductor 2|; I

through ia ,-path which includesathe wayside: relaycontacts and the winding ofwtransformer 19,;(which becomes the primary winding); back along the conductor 2| to the other end ofthe block; non-inductively through the centertapped coil I 9; and thence back tothe two rails- This circuit constitutes a. closed circuit ,loop

which'receives energy inductively from the ingtrain. I

"The energy thus trolled in accordance with signalindications in a manner to be described subsequently; is ,re. transmitted to the train in the following man: ner;-current flowing in the loop circuit just described induces an E. M. F. in the secondary (center tap'ped) winding of transformer -18. This causes current to flow transversely between the track rails over a path which startsincone ductors 5,16 and includes the rails 1 I, I2 and is completed through the wheels and axles of a return-transmitting circuit as wellas a non: interfering energy pick-up circuit. yInjth-e form described the two rails in parallel form the wayside energy pick-up circuit while vin series they function as thereturn-transmitting circuit. .It will be understood that conditions could bereversed, i. e., the usual transverse. rail circuit could be utilized for transferring the energy to.

as to be mutually aiding with respect to circuit 22, 24 and to send current into winding-23'-.of

received, after being .the train. In this way the trackrails serve as the receiving relay. An amplifier A, preferably J of. the vacuum-tube type, may be inserted in the circuit 22, 24 to increase the power available for operating the receiving relay. The circuit of 9'. The receiving relay is preferably of their-1+ duction type, supplied with exciting current from the generator l over conductors 25,26.

the pick-up coils may be tuned by a condenser Q 7 The system thus far described constitutes-fan electric wave transmission path which, extends from the train to the waysidepoint ofsignal control and then back again to the train. Both the outgoing and the return .paths are metallic circuits, and the looped transmission path, so

formed is to be distinguished'from a circuit com:

' posed of a single wire looped out and back. This looped path is establishedcontinuouslyduring the occupancy of a block by the train, and the return transmission is continuously available for the transmitting of signaliindications to the train. The signal indications arertransmitted as follows: I 1

1. In accordance with the closed 'circuit prim ciple of operation, the normal return transmission accomplishes by its receipt on the train the clear or proceed indication. The train relay is assumed to be throw'n'to the left, as showrr'for this condition,

2. For'the transmitting of the caution? indication'relay I8, is assumed tobe' released by the wayside block Isignal systenr effect of this is to reverse the relative instantaneous Q polarity of the current supplied to the rails from opens. the local train circuits, resulting in the display of the'danger indication in the locomotive cab and in the application of "a stringent speed limitation or a stop in accordance with practice well 'known in the art.

The wayside transmissionpaths of Figure 3 I may be superimposed upon the ordinary-block signal track circuits, as illustrated in Figure 4. The track'circuits are here. assumed to be of the direct-current-type. The superposition principle wouldbe the same, however, were theyot the alternating-current type. In the latter case the alternating-current provided on the train would bechosen to'be sufiiciently different in frequency from the alternating-current of the blocksystern to permit of separating the two sets of currents by frequency-selecting:means.

Referring now to Figure gfthe several block sections are designated I, -2, -3, 4.

The direct current for" block -2, for example, issupplied by battery-B2. Ihe current flows through the foli lowing path: the contacts of relay R1, through one set or" windings of transformer T2, to the rails AA; and along the rails to relay R2. The track relays are of the polarized type, having two sets of contacts, thosedesignated by the letter N-being the contacts controlled by the neutral winding-and those designated by the 'letter P being 'the contacts which are controlled by a change in the polarity of the-current. When the current is interrupted; the N'contact arms 7 release but the P contact arms hold. When the current is reversed-the N contact arms hold but the- P contact arms reverse. e' lhus, the regular block-signal direct-current circuit portion of Figure 4 will be understood to operate as follows: A train-occupying block 1 causes the N2 contact arms of-relay R1 to release. This reverses battery B2 of block 2 which in tur'n'reverses the P3 contact arms of relay R2. Battery I B3 is applied to block 3 in a normal manner andas'a result relay R3 holds both sets of contact arms Ni and P4 in the normal clear condition. These operationsare illustrative ofthe ordinary block signal andare not novel. "The portion of the wayside'system which is new and 'a part of the present invention, as

described in connection with'Figure 3, is shown as superimposed upon the. ordinary block circuit and may be traced in block 2 of Figure 4 as,

7 follows: 'The energ y supply circuit is, from the train intorails AA in'parallel, through the two line windings of transformerv T2 in" parallel mu-v tually opposing 'relation, along two of the N2 contact arms inparallel, to B2. Were the N2 contact arms drawn up by the actuation of relay R1, the circuit would continue: through one contact arm of P2, through the winding .(actu ally. the primary winding), of transformer T2,

, back through "the other. contact arm of Pz and 75.

back to the other end of the block over conductrain upon the rails.

When currentv is induced by a passing train in the longitudinal wayside'pick-up circuit AA, K, the current tends to be passed back to the train over a transverse circuit, formed of the railsin series; as follows: .The two secondary coils of transformer. T2 have series aiding E;-,M. FLs induced in them as the result of current'flow 'intheprimary circuit just delineated. The secondary E. M. Ffs tend to set up current flow around a circuit J5, it which is closed upon itself at one end by the. contacts of N2 and battery circuit B2, which includes the two rails AA in'series in the circuit, andwhich at the rail end is closed by the short-circuiting' effect of the The: ordinary D. C. track circuits of Figure 4 illustrate the three signal indications, stop, caution, and cleaiyto be set up for blocks 2, 3 and 4 respectively. 'In block 2 the stop indication is passed to the train-simply by opening at N:

the circuit which-picks up the energy from the train: The train=generated energy is not returnedto the train and, therefore, the receiving relay on the train'is released. In block 3 the caution signal is transferred to, the train by virtue of the relative reversal at P3 of the current which is fed back to the train. This results in a reversal of the train-carried relay in the mannerpreviously explained. In block 4 the clear or proceed signal condition is transferred to the train because the circuit is in suchconditidn as to send energy back to the train in relatively normal phase relation. Thus a train in passing along from block 4'to 3 to 2 will meet successively, and be subjected to con trol in accordance with, the clear, caution and stop indications.

Referring to the train-carried arrangement disclosed in Figure 3 it will be noted that a separate set of sending'and receiving coils is employed. Actually one pair of coils could be used as is done in the arrangement of Figure l. The separate coil arrangement has the advan- 'tage of improving the balance separation obtained between the superposed longitudinal and transverse circuits. In other words, the train re-- ceiving circuit is subject to less direct influence fromthe transmitting circuit because of the transmission loss which intervenes between the sending and receiving coils by virtue of their separation and by' virtue of their being placed on opposite sides (front and rear) of one or moretrucks of the locomotive.

Having now describedthe invention, what I claim .is:'

1. Awayside circuit for train'control purposes comprising two inductors, means for connecting the two inductors in parallel with each other in theciicuitfor transmission in one direction, from or to the train, and in serieswith each other in the circuit for transmission in the .reverse direction, means in the Wayside for interconnecting the two superimposed paths thus formed, together with means on the train whereby energy is received from said wayside circuit to thesubstantial exclusion of the energy which is transmitted into it.

2. In a train control system, a train-carried alternating current supply, a train-carried inductor unit including a combination of transmitting and receiving inductor coils, said coils being capable of being balanced in respect to the direct efiect of said source, together with an inert wayside circuit provided with a pair of inductors for receiving power from the traincarried source and for selectively influencing the train-carried receiver in accordance with trafiic conditions ahead. i

3. In a train-control system, a train-carried inductor Winding with a coacting wayside inductor forming one inductive coupling, a second train-carried inductor winding with a coacting wayside inductor forming a second inductive coupling, a connecting circuit on the train which combines theinductive effects of said two train-carried windings in series witheach other in the circuit for the transmission of signaling,

source of alternating current, a pair of traincarried inductor coils supplied with alternating current from said circuit, a train-carried signal receiving circuit utilizing the same pair of inductor coils, and means for so connecting the receiving circuit and saidfsource to the inductor coils as to prevent the alternating supply current from directly affecting the receiving circuit; together with a wayside circuit comprising two inductors and means for, connecting them in parallel with each other in the circuit for transmission of signaling current in one direction, from or to the train, and for connecting them in series with each other in the circuit for transmission in the reverse direction.

5. In a' system for transmitting signals between a train and the wayside; a two-wire circuit for transmitting in one direction between the vehicle and wayside, a circuit derived in part therefrom for transmitting in the reverse direction, comprising a third Wire connected to the midpoint of the two-wire circuit at each end and completed by the conductors of the two-wire circuit working in parallel, a transformer in the wayside, including primary and secondary windings, and'means in one winding thereof to make said midpoint connection, oneof said windings being included in said two-wire circuit and the other being included in the third wire of the derived circuit. i

6. In a train signaling system, the trackside arrangement which includes a two-wire circuit for transmitting signal current in one direction between train and trackside, a circuit derived in part therefrom for transmitting signal current in the reverse direction comprising a third wire connected at each end to a midpoint of the twowire circuit and completed by theconductors of the two-wire circuit working in parallel, said circuits including a transformer having primary and secondary inductive elements, one of said eIementsbeing divided into two equal coils which rent from directly affecting the receiving circuit;

together with a wayside circuit comprising two inductors and means including a transformer for connecting them in parallel with each other. in the circuit for transmission of signaling current in one direction, from or to the train, and

for connecting them in series with each other in the circuit for transmission inthe reverse direction.

I LLOYD ESPENSCHIED.

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