US1770705A - Railway-traffic controlling apparatus - Google Patents

Description

July 15, 1930.

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nllrnun \N Hnnulq 5Q S. M. LUCAS RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 12, 1928 'Qll ll') lllllll'blll "IIIII\UII ltllll'l'l III a I Fig.5.

INVENTOR;

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Patented July 15,1930

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r ssrars Parser 'FFEQE SAMUEL MQ LUCAS, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH 8: SIG-E'TAL GQM-PANY, OF S YVISSVALE, PENNSYLVANIA, A CORPORATION OF IPEIINSYLVANIA RAILWAY-TRAFFIC oonrnonnine APPARATUS Application filed September 12,1928. Serial No. 305,400.

My invention relates to railway traffic con trolling apparatus, and particularly to signaling and train controlling apparatus on an.

electric railway. More specifically, the invent-ion relates to an electric railway provided with a signaling system involving a lternating current of one frequencyin the track rails, and automatic train control sys-' tern involving alternating current of a different frequency in the track rails.

One feature of my invention is the provisionv of bonds for freely conducting the pro-- pulsion current from section to' section, but substantially preventing the flow of signaling current and train controlling current from rail to rail of each section.

Another feature of my invention is the provision, on an alternating current electric railway provided with a signaling system having alternating current track circuits,*of a novel and improved bond for freely con- .ductingthe propulsion current from section to'section but 1 substantially preventing the flow of signalingcurrent' from rail to rail of each section.

Twill describe two forms o fapparatus embodying my invention, and will then point out the-novel features thereof in claims. I

In the accompanyingdrawing, Fig. 1 is a diagrammatic view showing one form of apparatus embodying my invention; Fig; 2 is a fragmentary view showing a modification of the inductive bonds shown in Figl and also embodying my invention. Fig. 3

is avector diagram illustrating thegoperation,

of the bonds shown in Figsl and 2.

Similar reierence characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference char- 'actersIEand l designate the track rails of an electric railway along which trai'iic' norinally moves in the direction-indicated by the arrow. These rails are divided by insula-ted joints 2 to form a plurality of successive track sections, of which onlyone complete section A-B is illustrated in the draw-,

ing.' The railwaygi's of the electric propulsion type, and is therefore provided with a propulsion genera-tor G, one terminal of which is connected with a trolley or third 'whi'ch is connected across t rail T, and the other terminal of which is connected with the track rails 1 and 1 through a bond D which is similar to the other track bonds hereinafter described.

Located at the junction of each two'adjacent track sections are inductive bonds for freely conducting the propulsion current around the insulating oints 2. Each of these bondscoinprises two windings 3, one connectedacross the rails of each section, and a conductor l electrically connecting the middle points of the two adjacent windings 3. These bonds function in the usual and well known manner to conduct the propulsion current-from the generator G around the oints 2,-and detailed explanationof the manner in which this function isperform'ed is not necessary for the purpose of the present specifications Y i The railway is provided with a signaling system which involves an alternating current track circuit for each section. Thesourco of track circuit current for section A-B is a transformer C thesecondary of which is connected across the rails of the section, and

the primary of which is connected with a source of alternating signaling current, which isnot shownin the drawing. This signaling current actuates a track relay R 7 The railway is'also provided with an automatic train control system which involves the supply-of alternating traincontrolling currentto the track rails of each section. The source of train controlling current for section A-B is a traiisforiner C the secondary of he'rails of the section through a front contact 9 of track relay R for he section nextin advance, and

theprim'ary of which is connected with a source of alternating train controll ng current whlch is not shown in the dIEIWIH The frequencies of the signaling currnt and the train controlling current are dif will act to conduct a considerable portion of the train controlling current from rail to rail; whereas, if these bonds are tuned to multiple-resonance at the frequency of the train controlling current, they will act to conduct a considerable amount of the signaling current from rail to rail. To overcome this difliculty I tune eachbond 3 to multiple resonance at the frequenc of the signalin current andthe frequency 0 the train controlling current, To accomplish this, each bond is provided with a secondary winding 5 inductively related to the main winding A first condenser 6 is connected across the terminals of the secondary winding 5, and a second con denser 7 and a reactor 8 are connected in series across the terminals of winding 5. The condensers 6 and 7 and the reactor 8 are so chosen that the bond 3 is tuned for multiple resonance at both cycles per second and 100 cycles per second.

,4 Referring now to Fig. 3, as well as to Fig. 1,- the vector OP represents the voltage applied to the terminals of the bond 3. The line OG represents the magnetizing current taken by the bond at 25 cycles, this line beingdrawn to a scale corresponding to the impedance of the bond when viewed from the termintls of the secondary winding 5, and it la behind the voltage OP by approximag 0.2 power factor. The vector K-G represents the {current through condenser 6 atflficycles, and it will be noted that this vec- I tor leads the voltage OP by 90. The magnitude of the vector KG is so chosen that at c'ycles the inductive reactance of the bond and the condensive reactance of the condenser 6 are equal. The 50 cycle value is the geometric means between the high frequency aft-100cycles and the low frequency of 25 cycles. Considering now the path comprising the auxiliary reactor 8 and the second condenser 7, the voltage impressed across this path is also represented by the vector OP. Theyalues chosen for reactor 8 and condenser 7 args'ueh that at 50 cycles these two elements are ,i'nmeries, resonance, that is, at 50 cycles thevqltpge drops across reactor 8 and condenser? are equal and approximately opposite. Then when 25 cycle current is applied to this path, the relative drop across the reand the condenser changes in the ratio of to 4, this being due to the fact that at se ms the reactance of the reactor is halved and the condensive reactance of the condenser is doiihled With the voltageO-P applied tm thisauxiliary path, the vectors P-N and y rcpresent respectively the 25-cycle vol across the condenser 7 and the reactor 1 a! B. i l angle O-N-Pis the angle obtained when tlievect'or ON is laid off at the power factorgof the reactor ahead of the current through the path, and the vector N--P is laid oil at 90? behind the current. The ext s act-location of the triangle O-NP is deterinined from the three known factors, namely, angle O-N-P, side OP, and the ratio When the position of the vector ON is located, the vector OV is readily drawn representing the position of the current through the auxiliary path at 25 cycles. To the vectors OG and K-G, a third vector SK is drawn parallel to the vector OV and terminating at the point S on or closely adjacent to the vector OP. The vector 0S then represents the total current through the bond, and the bond is resonant at 25 cycles.

I will now consider the condition when IOU-cycle energy is impressed on the bond. The capacity and inductance of all elements remain fixed, but the impedance of the bond proper, and also the impedance of the reactor 8, will vary directly in proportion to the change in frequency, while the impedances of the condensers 6 and 7 will vary inversely as the frequency. Assuming for present purposes that the IOO-cycle voltage is the same in magnitude as the 25-cycle voltage previously considered, the vector OP will also represent the 100-cycle potential impressed on the terminals of the bond. This assumption as to relative magnitudes of the currents of the two frequencies is made solely to simplify the explanation, and is in no way essential for the correct and intended operation of the bond. The current through the bond proper, which is inductive, shrinks to 100 represented by the vector OH. The curof its 25-cycle value OG,and is now potential across the reactor is of the 25- cycle potential which was represented by the vector ON, and the IOO-cycle potential of the 25-cycle potential which was represented by the vector NP. By laying off and adding these IOO-cycle potentials with proper magnitudes and with proper phase angles between them, and then swinging the resultant vector about until it falls on the vector O P, we find the positions of the IOU-cycle vectors to be OQ and Q-P. The phase position of the current through the auxiliary path, is, of course, at 0.2 power factor behind the potential across the reactor OQ, that is, the phase position of the current is OT. From the point M, a vector is laid off representing the auxiliary path, which'vector is parallel with OT and across the condenser 7 is equal in magnitude to the vector K-S, and this new vector M-S terminates in point S, which means that the bond is resonant at 100 cycles per second.

Referring now to Fig. 2, the condenser 7 and reactor 8 are connected in multiple, and these two elements are interposed between condenser 6 and one terminal of the secondary winding 5. T his circuit is the electrical equivalent of: the secondary circuit for winding in Fig. 1, and, consequently, the foregoing discussion concerning Fig. 1 applies equally well to the modified form of bond shown in Fig. 2. e

In some instances, the propulsion energy may be an alternating current of one frequency, and the alternating signaling current may be of a difierent frequency, the train control current being omitted. bonds embodying my invention are advantageous because they are susceptible to broad tuning to the signaling current frequency, that is, asmall variation in the frequency of the signaling current causes very little change in the phase of the current taken by the bond.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood'that various changes and-modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my inventlon.

Having thus described my invention, what I claim is In such instances,

condenser and one terminal of said secondary windin 3. In'combination, an electric railway having its track rails divided into sections, a

source of alternating signaling current connected with the rails of each section, an inductive bond connected across the rails of each section, a connection between the middle points of the bonds for each two adjacent sections, a secondary winding inductively related to each bond, a first condenser connected across the terminals of each secondary winding, and a second condenser and a reactor connected in series across the terminals o1 each bond.

4. In combination, an electric railway having its track rails divided into sections, a source of alternating signaling current connected with the rails of each section, an inductive bond connected across the rails of each section, a connection between the middle points of the bonds for each two adjacent sections, a secondary winding inductively related to each bend, a condenser connected with said secondary winding, and'a second condenser and a reactor connected in multiple and interposed between said first condenser and one terminal of said secondary windin In testimony whereof, I aflix my signature.

SAMUEL M. LUCAS.

1. In combination, an electric railway having its track rails divided into sections, a source of alternating signaling current con nected with the rails of each section, means for supplying the rails of eachsection with alternating train controlling current dillering from the signaling current in frequency, an inductive bond connected across the rails of each section, a connection between the middle points of the bonds for each two adjacent sections, a secondary winding inductively related to each bond, :1, first condenser connected across the terminals of each secondary winding, and a second condenser and a reactor connected in series across the terminals of each bond.

2. In combination, an electric railway hav ing its track rails divided into sections, a source of alternating signaling current connected with the rails of each section, means for supplying the'rails of each section with multiple and interposed between said first

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