Патент USA US2135548код для вставки
Nov. 8, 1938. J. E. WILLING 2,135,548 ' TRACK CIRCUIT FOR RAILROADS Filed June 14, 1934 h, ATTORNEY 2,135,548 Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE 2,135,548 TRACK CIRCUIT FOR RAILROADS Joseph E. Willing, Rochester, N. Y... assignor to General Railway Signal Company, Rochester, N. Y. Application June 14, 1934, Serial No. 730,646 5 15 30 40 12 Claims. (Cl. 246-41) This invention relates in general to track cir track shunt due to track ballast and a rapid cuits such asused in railway signalling practice change in track shunt due to’ train occupancy. and has more particular reference to means for Further objects, purposes and characteristic increasing the e?iciency ofshunting and dis features of the invention will appear as the de criminating between a shunt provided by a train scription, progresses, reference being made to the in the track section and a shunt due to ballast accompanying drawing which shows by way of conditions. example one ' form that the invention may In railway operation it is quite essential that assume. the track relay connected across the track section The single ?gure diagrammatically illustrates at one end of a signalling block be su?iciently one form of the present invention applied to a energized. when the block is unoccupied to pick single stretch of track. up and hold up with certainty. It is likewise Apparatus-A section of railway track includ essential that the occupancy of the track section ing rails I is shown separated from the adjacent willeffectively shunt the relay so that it will be track sections by insulated joints 2. A track positively released. For examplain the usual battery B and a limiting resistance D are shown track circuit if the normal holding current is connected to the track rails at the right hand end too high, shunting may not be effective to drop of the illustrated track section. The primary the relay and if the normal holding current is winding of a transformer TR is included in so lowthat shunting will bemore positive, then series with the circuit extending from the lower it is possible that at times the holding current track rail‘ to the track battery, the secondary of may be insu?icient to hold the relay in its picked this transformer being connected to a relay G up 7 position when the track section is not which is for the purpose of including and exclud occupied.-' ing resistance Hfrom the track circuit for lock Taking the above into consideration. it will be ingv relay A, as will be later described. seenthat the usual variation in ballast resistance Relay A is normally energized and when it encountered in practice, due primarily to changes drops to close its normally open back contact, in weather’conditions, ~may operate to interfere resistance 0 is removed from the track circuit. with the proper operationiof the track relay un The limiting resistor D is adjustable in order to less some means is‘ provided for discriminating regulate the current ?ow from battery B to the between changesdue to ballast leakage and track track rails for the most efficient operation. occupancy. Track relay T is shown connected across the As the ballast resistance increases, the leak track rails at the left end of the illustrated track age current between the rails decreases so that section. As typical of the control exercised by the voltage across the terminals of ‘ the‘ track the track relay, a semaphore signal SG is illus relayconnected to the track circuit increases. trated and it will be understood that any suitable Conversely as the ballast resistance decreases, type of signal may be used, of which SG is merely ballast leakage» increases and the terminal volt a typical example. age'at the relay terminals decreases. Unless proNormal conditi0ns.—With the circuit in its vision is‘ made for regulating» the current ?ow normal condition as illustrated in the ?gure, through the relay this current will vary over a track relay T is normally picked up over a circuit considerable’ range and'possibly cover a range at’ times which-will prevent proper response of the relay- under occupied and unoccupied conditions Mi of the track section.‘ , It-is'proposed in- accordance with this invention to providemeans- associated with the circuit of a track section for detecting changes due to track occupancy’ and unoccupancy and changes due to leakage currents caused by variation in ballast resistance-between the rails of the track. In accordance with the present invention it is also proposed toimproverthe shunting ei?ciency of the track circuitand for thispurpose a discriminat ing arrangement is included in the track circuit 55; which~>discriminates between aslow change in’ 5 1O 25 30, 35' extending from the (+) terminal of battery B, primary winding of transformer TR, lower track rail, winding of relay T, upper track rail, resist~ ances D and C in series to the (—) terminal of battery B. The current ?ow in this circuit main 45 tains relay T in its picked up condition. A cir cuit in‘shunt of relay T and the primary winding of transformer TR includes the winding of relay A and resistance H in series. Under normal or dry ballast conditions current through this shunt circuit is effective to maintain relay A in its picked up position. This circuit may be traced from the (+) terminal of battery B, resistance H, winding of relay A, resistances D and CV in series to the (-) terminal of battery B. 2 2,135,548 Ballast changes-A decrease in resistance be tween the rails of the track due to the ballast conditions changing (by increasing the shunt path between these rails) tends to reduce the cur rent flow through the shunt path including relay A because of the increased potential drop across the circuit including the primary winding of transformer TR and relay T, which drop reduces the potential drop across the'circuit including relay A and resistance H. tain the circuit in condition for greatest train shunting efficiency. . ' Itwill also be noted that relay G, transformer TR. and resistance l-I provide the lockout of re lay A on instantaneous shunt and that these ele—. ' merits remove the lookout of relay A on quick re moval of the shunt, thus making the locking out and the removal of the locking out functions re sponsive to train shunt but not responsive to changes in ballast resistance caused by Weather 10 Consequently when the leakage current due .to . conditions. It will be understood that the lock ‘out of relay A due to track occupancy is the re-. an impaired ballast condition increases'to a pre determined value, relay A is suf?ciently shunted to drop its armature. The closure of back contact 15 3 of relay A short circuits resistance C which re moves this resistance from the circuit leading to the track rails so that more current flows through the track rails and relay T in series. The effect is, therefore, to increase the current ?ow through relay T when the ballast shunt reaches a value which causes relay A to drop. As ballast condi moval of resistance H by the operation of relay G to give relay A morecurrent so that it will re main in its picked up position. Under the worst ballast conditions, when relay - A has dropped its’ contact 3 and removed resistor C from the ‘circuit, then the entrance of a train into the track section causes relay G to operate contact 4 to its left hand dotted position which re moves resistorll from the circuit including the winding of relay A.- This increases the shunt tions improve, a point will be reached where the ballast resistance is increased to such a value that across track relay T as before which assists in dropping this relay but under this condition relay the effective shunting effect of relay A is dimin 25 ished to the point which will allow relay A to pick 7 A remains down because it is effectively shunted 25' up and again insert resistance C in the track cir cuit for placing the circuits in the conditions illustrated in the ?gure. signal' circuits of signal vSG or for any other pur ‘ Track oceupancy.-Assuming that ballast con pose required by the usual practice in connection 30 ditions are such that relay A is picked up, the entrance of a train into the illustrated track section causes a sudden increase of current through the primary winding of transformer TR due to the sudden shunting of relay T. This sud by the'train. ‘ ' Contact 5 of relay T may be used to control the with track relay circuits. ' Summary-With the track-conditions normal ' (high resistance shunt due to a dry track), the track relay T is maintained energized as long as the track is unoccupied by means of current flow 35 den rush of current through the primary wind ing of the transformer sets up a potential across ing from battery B through resistors C and D and the primary winding of the transformer. in series. the secondary winding, including the winding of 'When a train enters the track under this condi-, the mag-stick polar relay G, in such a direction tion. the low resistance shunt placed across the‘ that relay G operates its polar contact 4 to the _ track rails causes an increase of current ‘?ow It will be understood that although this in duced current in the secondary winding of the transformer is only momentary it is of sufficient through resistors C and D and the primary wind ing of transformer TR. Due 'to the shunting duration to operate the contact of relay G. Contactr4 actuated to its left hand dotted posi vtakes place in track relay T, regulator relay Aand 40 left. 45 tion short, circuits resistance H which decreases the resistance of the shunt path across the track circuit by removing this resistance. This de crease in the shunt resistance has the effect of increasing the sensitivity of relay T to the train 50 shunt. } ' When'the train leaves the illustrated track sec tion, the sudden removal ‘of the shunt across track relay T causes 'a sudden decrease in current through the primary winding of transformer TR which induces a potential in its secondary wind ing opposite to that previously described, which is eifective to operate contact 4 of relay G to" the right. This removes the short circuit from re sistor H which places the circuits in the condition 60 shown in the drawing. ' Since relay G is of the polar type and since it is energized by an impulse of current quickly gen erated in the secondary winding of the trans former, it will be understood that the response of' 65 its ‘contact 4 is substantially faster than the re. sponseof contact 5 of relay T, both when the track section becomes occupied and when'it becomes unoccupied. I ' ‘ . 40" effect of the train a reduction in current flow resistor H; ' ‘ r ' ' y a This sudden increase in current through the primary of the transformer operates contact 4 of relay G to the left which removes resistor H from the circuit‘ by short circuiting it. This causes a further increase in current flow through resistors C and D and a" further reduction in current flow 50 through relay T (because of the increased shunt conductance) ‘as well as an increase in current ?ow'through the winding of relay A. All of this is eifective to accomplish the release of relay T. Whenthe train leaves the track section under this condition the current ?ow through resistances C and D is suddenly reduced which is accom panied by a sudden reduction of current’ flow ' through the primary of transformer‘TR as well 7 as an increase in current ?ow through the wind ing of relay A and through the winding of relay 'T. This sudden reduction in current 607' flow through the‘ transformer winding is effective to operate contact 4 of relay G to the right which inserts resistance H in the circuit for further re ducing the current ?ow through resistances C and D and the winding of relay A, while the current flow through relay T is further increased' When the rails of the track are slowly shunted From the above description it will be noted that relay A acts as a potential relay which cuts out resistance C when track ballast resistance is low and cuts resistance C back in the circuit when the ballast resistance increases to a predeter due to the ballast ‘conductance changing in re 70 sponse to wet weather conditions, the current through resistances C and D and the primary mined cut-over point, which is effective to main? flow through relays T and A and resistorH‘ until 755: windingof transformer TB is slowly increased. This condition effects a reduction in ' current 2,1 85,648 a point is reached where'relay A drops its-back contact to» shortcircuit resistance C. This re-' What I claim is:1. An automatic voltage regulator for a track moves resistance C from: the circuit, effecting a circuit comprising; a source of current connect ed'to the rails of a track; a resistor in the con-. nection/between said source and said rails; a slight sudden increase in current through resis tor Dandv the primary winding of transformer TR" aswell as through thewindings of relays T and A ‘and the resistor H.- This'slight increase in» current is not sufficient to cause the opera tion of relay G. 10 When a train enters the track section under this condition, a'sudden and large increase of’ current ?ow takes place through resistor D and theprimary- winding of transformer TR While a reduction in current flow takes- place through 15 the winding of relays T and A and resistor H. This; sudden increase in current through the transformer operates contact 4 of’ relay G to the left which short circuits resistor H and re moves-it from the circuit, thereby causing a fur 20 ther increase in current flow vthrough relay A as well as a reduction in current ?ow through the primary winding of transformer TR and the winding of relay T.‘ When the train leaves the track section, a 25 reduction'in current ?ow takes place through resistor D and the primary winding of trans ._ former TR as well as an increase in current flow through the windings'of relays A and T. This sudden reduction in current flow through the 30 transformer winding operates contact 4 of relay G- to the right/which inserts resistance H in the circuit for further reducing the current flow through resistor D and relay A and for increas ing the current ?ow through the primary wind 35 ing of transformer TR and the winding of track relay T. When the track is occupied, an increase in the shunt across the rails due to a wet track condition has the effect of applying an additional 5:0 shunt to track relay T and since this relay is already shunted‘ down by the train this condition has no noticeablee?ect. Relay A will not drop under this condition because resistance H is shunted out and when the train leaves the track section resistance H is cut into the circuit which may or may not drop relay A, both of which ap plies more current to track relay T for causing it to pick up. The drying out of the track ballast during 50 track occupancy has no effect on relays T or A because relay T is effectively shunted by the train and since this shunt is not noticeably changed by the drying out of the ballast, relay A does not change its position. When the train leaves the track section under this condition re sistance H is 'cut into circuit which supplies re lay A with more current so that it will receive su?icient current to pick up if the track has 60 3 dried out to the cut-over point. It will be clear from the above description that this invention provides means whereby there is a positive discrimination between the track cir cuit conditions due to track occupancy and due to ballast leakage and that changes in ballast 65 leakage condition the circuits for more ef?cient track relay connected across the rails of said track; a second relay connected in shunt of said track circuit; said second relay being adapted to effectively exclude said resistor from said con nection when the voltage of said track circuit 10, falls below a predetermined value and to effec tively include said resistor in said connection when the voltage of the track circuit increases above a predetermined value; and auxiliary means for effectively including a second resistor 15 in and excluding it from said shunt. 2. An automatic voltage regulator for a track circuit comprising; a source of current connect ed to the rails of a track; a resistor in the con nection between said source and said rails; a .20 track relay connected across the rails of said track; a second relay connected in shunt of said track circuit, said second relay being adapted to effectively exclude said resistor from said con nection when the voltage of said track circuit 25 falls below a predetermined value and to- effec tively include said resistor in said connection when the voltage of the track circuit increases above a predetermined value; and auxiliary means for effectively including a second resistor 30 in and excluding it from said shunt, said aux iliary means responding only to a rapid change of current flow in said track circuit caused by the sudden application or removal of a vehicle shunt. 3. An automatic voltage regulator for track circuits, comprising, in combination with the track circuit and a source of current supply for said track circuit having an adjustable resistance in series therein, a second resistance connected in series with said adjustable resistance and the source of current supply, contact points electri cally connected between the two resistances and the‘ current supply, a relay and a third resistance in series included in multiple with said resistances and said source, means controlled by said relay for causing said contact points to effectively in clude and exclude said second resistance from said circuit, said relay being responsive to the slow increase and the slow decrease of the shunt resistance across said track circuit to control said contacts. and means responsive to the quick ap plication and the quick removal of a shunt across said track circuit for effectively excluding and including said third resistance whereby the oper ating and release voltage values of the circuit of said relay are varied. 4. In combination, a section of railway track, 35 45 50 55 a source of current connected across the rails of said section, a ?rst relay receiving energy from 60 the rails of said section and responsive to the steady value of current with which it is supplied, a second relay, means also receiving energy from the rails of said section for energizing said second relay when the value of the current received by 65 shunting of the track relay by the train. said means is changed due to the entrance of a The above rather speci?c description of one form of the present invention has been given solely by way of illustration and is not intended train into said section, said means being incapable of responding to the steady value of such current, and means controlled by said second relay for de 70 creasing the energization of said ?rst relay. 5. A track circuit for a section of railway track 70 in any manner whatsoever in a limiting sense. It will be obvious that the general principles herein disclosed may be embodied in many other . organizationswidely di?erent from that illus trated without departing from the spirit of the 75 invention as de?ned in the following claims. including a source of unidirectional current; a transformer having its primary winding included directly in said track circuit; a polarity responsive device included directly in series in the secondary 75 4 2,135,548 winding of said transformer; a track relay ener ' 9-. In combination, a section of railway track, a gized to an extent. depending upon the value of current ?owing .in said track circuit; and means including a contact of said polarity responsive source of current connected across the railsrof device actuated, in response toga sudden increase into said section, and means including a contact 5 in the current in the vprimary winding of said‘ transformer, to a‘ position to decrease the degree controlled by said device for shunting the rails of said section when artrain enters the section. ' of energization of said track relay; whereby said track relay'is also controlled in accordance with a source of current connected across the rails of the rate of change in a particular direction of cur 10 rent ?ow in said track circuit. 6. VA track circuit for railroads comprising, a section of railway track, a source of unidirectional current connected across the track rails at one ' end of said section, a track relayreceiving energy 15 from the track ‘rails at the other end of said sec tion, a transformer having its primary winding nected across the other end of said track; electro magnetic regulating means connected to the track current in the track circuit caused by the en trance of a train into said section for decreasing the current through said track relay to release its . said section, a track relay receiving energy from 10 said rails, a device receiving energy from said source and responsive to the entry of 'a train in said section, and a shunting path ‘for the rails of said section controlled by‘said device. , 11. In a track circuit; in combination with an 15 insulated stretch of track; a source of current connected acrossone end and a track relay con relay energized only by-current induced in the secondary winding of said transformer, and oper ‘ 10. In combination, a section of, railway track, included in said track circuit; and an auxiliary 20 ated in response to the relatively quick change of 25 said sections, a relay, receiving energy from said rails, a device responsive to the entry of a train armature. _ 7. A track circuit for railroads comprising, a uni-directional source of current and a track re lay in series, a transformerhaving itsprimary winding included in, said track circuit, and an auxiliary relay energized only by current induced in the secondary winding of said transformer and causing operation of a contact to a particular position only when current in one direction is in duced in said secondary winding by the relatively ‘ . quick change in the current in said track circuit 35 caused by the entrance of a train upon said track circuit, said contact when operated to said par ticular position acting to decrease the current through said track relay to release its armature. 8. In combination, a section of railway track, a source of current connected across the rails of said section, signaling apparatus receiving energy from the rails of said section, a device responsive to the entry of a train into said section, and a shunting path for the rails of said section con '45 trolled by said device. rails at said one end for automatically increasing the current supplied to said track when the, volt- , age across saidone end due to slow variations in the inter-rail resistance falls below a particular value; and impulse actuated means responsive to. a rapid decreasev in said inter-rail resistance for 25 causing a decrease in the current supplied to said 1 track below that existing immediately after such rapid decrease in inter-rail resistance occurred, said impulse actuated means comprising a polar relay operatedgto one position in response to a 30 rapid increase ininter-rail resistance and to an other position in=response to a rapid decrease in inter-rail resistance. 7 ' v ' 12. In a track circuit, a track relay, track rails, a‘ regulator relay arranged to automatically in 35 crease the energizing current through said track rails and track relay when the potential across the track rails adjacent said regulator relay due to ‘weather conditions on’ said track circuit falls below a particular value, and an impulse actuated locking means inductively coupled with said track circuit so as to be distinctively responsive to the shunting of said trackrrails by a train for when assuming ‘one condition preventing a change in position of said regulator relay. ' V JOSEPH E. WILLING.