US2131752A - Coded continuous inductive train control system - Google Patents

Description

Oct. 4, 1938. w. H. REICHARD ET AL 2,131,752

CODED CONTINUOUS INDUCTIVE TRAIN CONTROL SYSTEM Filed Nov. 2'7, 1936 Red FIG. 2;

I Am U $413 15 J INVENTORS NHTeicrzard & (IS-Bushnell T 1 BY ZMQHM;

! THEIR ATTORN EY Patented Oct. 4, 1938 UNITED STATES PATENT OFFICE CODED CONTINUOUS INDUCTIVE TRAIN CONTROL SYSTEM Application November 27, 1936, Serial No. 112,858

9 Claims.

This invention relates to automatic train control systems for railroads and more particularly to systems of the type commonly known as coded continuous inductive train control systems.

One object of the present invention is to provide a three indication continuous inductive system of control whereby conditions in the field will determine the presence of one of two train control currents of different frequencies in the track rails, and means whereby such currents can be transmitted to a moving vehicle in a simple and direct manner to produce the various indications.

Another object of this invention is to provide, by arrangement and organization of parts, means whereby car-carried apparatus is protected against false indications due to the presence of stray currents in the tracks.

Other objects, advantages and characteristic features of this invention will be in part apparent and in part pointed out as the description of the invention progresses.

The trackway apparatus, in accordance with this invention, is such that under high speed running conditions, an alternating current of 140 cycle frequency will be connected across the rails at one end of the track section, and under caution conditions a current of 90 cycle frequency will be connected across the rails in a similar manner. The frequencies of 90 and 140 cycles have been selected, because these frequencies'are higher than the 25, 50 and 60 cycles ordinarily used for power and industrial purposes, and thus avoid interference by these commercial frequencies and their ordinary harmonics.

In describing the invention, reference will be made to the'accompanying drawing which shows. in a simple and diagrammatic manner, wayside and car-carried apparatus constituting one spe- 40 cific embodiment of the invention, the parts being shown in a manner to facilitate explanation and understanding of the essential characteristics of the invention, and not necessarily to show the particular organization and construction that may be most advantageously used in practice. In the drawing:-

Fig. 1 is a diagrammatic view of one form of the invention.

Fig. 2 is a fragmentary diagrammatic view of parts in one operating position.

Fig. 3 is a fragmentary view of parts in another operating position.

The symbols and are employed to indicate the positive and negative terminals, respectively, of suitable batteries or other sources of electrical energy, and those terminals with which these symbols are used are presumed to have current flowing from the positive terminal designated to the negative terminal designated When these symbols are used in connection with alternating current circuits they are considered to represent the instantaneous polarity of the respective terminals.

Referring to Fig. 1 of the accompanying drawing, asection of single track is shown with the track rails I divided into blocks by insulated joints 2, blocks C and D, and the adjacent ends of blocks B and E having been shown. These blocks may be provided with block signals or these signals may be omitted and reliance placed on cab signals. Semaphore signals S are shown conventionally without attempting to illustrate their control circuits which may be of any well known type or form.

Suitable track relays T are connected across the track rails at the entrance end of each block, these relays being normally energized by track batteries 4 connected across the rails at the exit end of each block. Train control current is supplied to the rails of each block by transformers 5, the secondaries of which are connected in series with the track batteries '4 and their usual limiting resistances 6. The primary of transformer '5 of each block is connected to a source of current of either 140 or cycle frequency through front and back contact '1 respectively of the track relay T of the block next in advance. Therefore, it will be noted that current of 90 cycle frequency will be connected across the rails at the exit end of the block next in the rear of an occupied block through back contact I of the track relay of the occupied block, and current of cycle frequency will be connected across the rails of the second block in the rear of the occupied block through front contact 7 of the track relay of the block next in advance, and likewise for all blocks to the rear. The direction of current flow in each of the track circuits has been indicated by the arrows a and a and is in opposite directions in the two rails. It is obvious that any vehicle will always so shunt the track circuit that no train control current will be present in operating intensities behind, or in the rear of, a vehicle.

A locomotive or vehicle equipped with train control apparatus is shown conventionally in the drawing as comprising a pair of wheels and axle 8, which represent the first or leading pair of trucks of the vehicle. Carried ahead of the wheels and in inductive relation to the rails, are

receivers R and R of any usual construction. The voltages induced in the receivers R and R by the flow of train control current in the track rails, produce currents that are passed through band pass filters BPF and BPF of any usual construction, to the in-put side of suitable ampliflers A and A of the vacuum tube or other type. These amplifiers are constructed in conformity with recognized principles to amplify the currents induced in receivers R and R by the train control currents in the track rails. The band pass filters are designed to greatly attenuate any circulating stray currents of frequencies below cycles and above cycles. Each receiver has its own filter and amplifying circuit and its own out-put circuit connected to a poly-phase primary relay PR.

The relay PR is of the induction motor type, but is of special construction and is provided with three sets of windings, one set of windings 9 corresponding to the local winding of a polyphase relay and energized through a circuit which includes receiver R filter BPF and ampli fier A Windings Ill and H are both connected to an out-put transformer l2, of amplifier A, and are so tuned respectively, to 90 and 140 frequencies that but one or the other winging receives current of operating intensity when current of one frequency is present in the rails. In other words, and as shown in the accompanying drawing, winding II is tuned so that it is much more strongly energized than is winding ID, by current of 140 cycle frequency, and winding I0 is tuned so that it is much more strongly energized than is winding H, by 90 cycle current. Thus in a block which is clear, or under high speed running conditions, 140 cycle current is applied to the relay PR, and the energy in coils 9 and H produces a torque which operates the rotor of relay PR in a clockwise direction and closes contacts l3 and M to the left. In a like manner, when current of 90 cycle frequency, which corresponds to a caution condition, is present in the rails, current is applied to the relay PR and the energy in coils 9 and Ill produces a torque which operates the relay in a counterclockwise direction and closes contacts [3 and M to the right.

In order to produce operating torque in relay PR it is necessary that the time phase of the existing currents in windings 9 and ill, or 9 and It of the relay should be displaced with respect to one another and to be in quadrature or as close thereto as practical. A sufficient angular displacement of these field currents is produced by the adjustment of the separate amplifiers A and A Fig. 2 shows the position contacts l3 and M will assume when relay PR is deenergized. Referring specifically to contact l3 it is obvious that, with contact 13 biased to the position shown coils l0 and H are both connected to a secondary coil of transformer l2 but the direction of rotation of relay PR will be determined only by the coil tuned to receive the particular frequency applied.

With contact 13 positioned as shown in Fig. 2, a movement of the contact finger through an arc of approximately 10 either to the right or left is sufficient to break the right and left-hand contacts respectively. A movement of contact finger l4 through an arc of approximately 45 is necessary to close either its right or left-hand contacts.

Fig. 3 shows theposition of contacts l3 and l4 after relay PR is moved to its right-hand position the result of a current of 90 cycle frequency being applied to the coils of the relay.

The relay PR may be employed to control any suitable or desired form of automatic train control indicating apparatus, which is controlled by three influences or controls corresponding to said relay being deenergized or energized to a clockwise or counterclockwise position. One suitable form of such application is shown in the drawing, it being understood that this application could be amplified so as to include acknowledging contactors and audible indications, etc, if desired, without departing from the scope of the invention, such, for example, as shown in Patent No. 1,703,831, issued February 26, 1929, to W. H. Reichard.

Assuming block E to be occupied, as shown, by a vehicle V, when vehicle 8 is in a clear or green block, as C, or B, as shown, alternating current p.

of I40 cycle frequency is applied to the rails through front contact I of a track relay T and transformer 5. The currents induced in receivers R and R are applied to relay PR to cause relay PR to operate in a clockwise'direction and close contacts l3 and M to the left. This energizes the green indication G in the cab, through a circuit traced from positive battery, contact I l in its left-hand position, green light G, to negative battery.

If vehicle 8 enters track section D, 90 cycle current, supplied to the rails through a transformer 5 and back contact 1 of a track relay T will cause relay PR to operate in a counterclockwise direction and close contacts l3 and I4 to the right. The green indication G will be extinguished and the yellow indication Y will then be displayed in the cab through a circuit which may be traced from positive battery, contact M to the right, the yellow indication light Y, to negative battery.

If vehicle 8 moves into the occupied track section E, relay PR will assume its deenergized position as no appreciable energy is present in the rail to the rear of V. Contacts 13 and I4 will then assume their energized neutral biased position and the red indication R will be displayed in the cab through a circuit obvious from the drawing. 1

One of the important features of this invention is the protection afforded against false operation of relay PR by stray currents in the rails of a frequency the same as, or close to, the regular train control current. Such stray currents may be falsely applied from a transmission line due to crosses, grounds and the like, or may come from some foreign source, of a frequency so like the train control frequencies that the band pass filters and the amplifiers are not sufficient to avoid operation of relay PR for large values of stray current. Such stray currents ordinarily flow in one rail alone or in both rails equally or unequally but in the same direction for any given instant.

The application of the amplifiers A and A in connection with theoperation of relay PR can guarantee operation only from currents which are derived from an inter-rail potential, and when the current flows down one rail to the shunting axles of the vehicle, and back to the source over the other rail. This is the case for the reason that the coils are so arranged that the instantaneous polarities of the currents in these coils are such that eifective operating torque is available in relay PR only'when the iii] currents in the track circuit flow in opposite directions i. e.,.in a loop circuit.

If a condition be assumed in which the vehicle carrying train control equipment is in a danger or red block, and a current of train control frequency is flowing in one rail only, it is evident thatrelay PR will not operate as only one of its coils is energized.

If, however, under the same conditions, currents of operating frequency were present in both rails and in the same direction, (i. e. simplex current in the rails) the instantaneous relative polarity of one of the receivers is reversed, with respect to the other. Ordinarily this would produce an operating reverse torque in the out-put circuit, and in the ordinary polyphase induction motor-type relay reverse operation would take place. In order to prevent such operation it will be noted that the circuit to winding II which normally produced clockwise torque, (i. e., with loop current in the rails) is'broken through contact 13 of relay PR, which opens when the relay moves in a counterclockwise direction. Also the circuit for winding 10, which produces counterclockwise torque with loop current in the rails, is broken when the relay is moved in a clockwise direction. Therefore, it is clear, that if the relay should tend to operate, due to stray circulating currents which flow in the same direction in both rails, the response of the relay to such a condition will be in a direction to interrupt or disconnect the operating field which produced such an initial movement.

If a condition be assumed in which vehicle 8 is in a yellow or caution block and a stray current of 140 cycle frequency corresponding to a clear block, is present in the same direction in both rails, the stray, current will have no effect on relay PR as the circuit to coil II is opened as indicated by the position of contact 13 in Fig. 3. The presence of astray current of cycle frequency will not effect the operation of relay PR when the vehicle carrying train control apparatus is in a green block ascontact I3, as shown in Fig. 1, will open the circuit to coil II].

If vehicle '8 enters either a green or yellow block in which the stray current in both rails is of the same frequency as the train control frequencies, relay PR in each case will have a tendency to operate in a reverse direction. However, the circuit that supplies the energy for this reverse operation will be interrupted as heretofore described by the operation of contact l3. As a result, if, for example, when vehicle 8 is in a green block and a stray current of cycle frequency appears in both rails, contact l3 of relay PR will move from its position, as shown in Fig. 1, to a position slightly to the right of that shown in Fig. 2, at which point the left-hand contact I3 will be open. The relay will then operate to intermittently close and open contact l3 but the signal control contact I4 will not move through a sufficient arc from its position shown in Fig. '3, to close its righthand contact. Thus, in the circumstances assumed, a flashing redindication will be displayed in the vehicle after the green indication has been extinguished. Likewise, if vehicle 8 is in a cautionor yellow block and a stray current of 90 cycle frequency appears in both rails, relay PR will operate in a manner similar to that described above, i. e., in a manner that will result in a flashing red indication being displayed in the car after the yellow indication has been extinguished.

The above rather specific description of one form of system embodying the present invention, has been given solely byway of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, the invention can assume many different physical forms, and is susceptible of numerousmodifications, and all such forms and modifications are desired to be included by this invention, as come within the scope of the appended claims.

Having described our invention, we claim:

1. In a train control system, in combination, trackway apparatus for placing current of two different frequencies on the rails in a loop circuit, in accordance with traflic conditions ahead, car-carried apparatus, including two receivers energized by the track rail currents of either frequency, a three-position relay of the induction motor type having a local winding and a normal and a reverse winding, a circuit including the local winding and one receiver, and a circuit connecting the other two windings to the other receiver, and means tuning the normal winding for one of the frequencies of rail current, and the reverse winding for the other frequency of rail current whereby the relay is energized to one or the other of its extreme positions in accordance with the frequency of rail current in the rails, means biasing the relay to a central position, and three condition indicating means distinctively controlled by the relay.

2. In a train control system, in combination, trackway apparatus for placing current of either of two different frequencies on the rails in a loop circuit, in accordance with traffic conditions ahead, car-carried apparatus, including two receivers energized by the track rail currents of either frequency, a three-position relay of the induction motor type having a local winding and a normal and a reverse winding, a circuit including the local winding and one receiver, and a circuit connecting the other two windings to the other receiver, and means tuning the normal winding for one of the frequencies of rail current, and the reverse winding for the other frequency of rail current whereby the relay is ener gized to one or the other of its extreme positions in accordance with the frequency of rail current in the rails, means biasing the relay to a central position, and three condition indicating means distinctively controlled by the relay contact control.

3. In a train control system of the continuous inductive type, car-carried apparatus including a relay having a local winding, a normal winding, and a reverse winding, means responsive to rail current for applying current of one character, or another character to the windings of the relay, means permitting the local winding and one only of the other windings to be energized at any one time dependent upon the character of the current applied; the relay being operated to its normal, or reverse, position upon its normal, or reverse winding being thus energized.

4. In a train control system of the continuous inductive type, car-carried apparatus including a relay having a local winding, a normal winding, and a reverse winding, means responsive to rail current for applying current of two different frequencies to the windings of the relay, and the normal and reverse windings being tuned, respectively, to one, and the other, of such different frequencies, the relay being operated to its normal, or reverse position upon its normal or reverse winding being thus energized.

5. In a train control system of the continuous inductive type, car-carried apparatus including a relay having a local winding, a normal winding, and a reverse winding, means responsive to rail current for applying current of one character, or another character to the winding of the relay, means permitting the local winding and one only of the other windings to be energized at any one time dependent upon the character of the current applied; the relay being operated to its normal, or reverse, position upon its normal, or reverse winding being thus energized, a winding control contact on the relay, means biasing the contact to a central position Where it closes an energizing circuit for both normal and reverse windings, said contact opening the circuit for either the normal, or the reverse, winding upon movement of the relay a short distance from its biased neutral position.

6. In a train control system of the continuous inductive type, car-carried apparatus including a relay having a local winding, a normal winding, and a reverse winding, means responsive to rail current for applying current of one character, or another character to the winding of the relay, means permitting the local winding and one only of the other windings to be energized at any one time dependent upon the character of the current applied; the relay being operated to its normal, or reverse, position upon its normal, or reverse winding being thus energized, a winding control contact on the relay, means biasing the contact to a central position where it closes an energizing circuit for both normal and reverse windings, said contact opening the circuit for either the normal, or the reverse, winding upon movement of the relay a short distance from its biased neutral position, the currents being of different frequencies, and the normal and reverse windings being tuned, respectively, to one, and the other, of such different frequencies.

7. In a train control system of the continuous inductive type, in combination, trackway apparatus with means for placing one of two frequencies on the track rails in a loop circuit, in accordance with traffic conditions ahead, carcarried receiving apparatus, including two receivers energized by track rail currents of either frequency, a three-position relay of the inductive motor type having a local winding and a normal and a reverse Winding, a circuit including the local winding and one receiver, and a circuit connecting the other two windings to the other receiver by means of a winding control contact, means tuning the normal Winding for one fre quency of rail current, and the reverse winding for the other frequency of rail current, the relay being energized to one on the other of its extreme positions in accordance with the frequency of the loop circuit current in the track rails, and means biasing the relay to neutral position with no loop current in the rails, to display the most restrictive indication, and means whereby said winding control contact operates to break the circuit to either the normal or the reverse winding when the relay responds to a simplex rail current of either said one, or said other, frequency respectively, to display the most restrictive indication.

8. In a train control system, in combination,

trackway apparatus for placing any one of a plurality of currents, of frequency determined in accordance with traffic conditions ahead, on the rails in a loop circuit, whereby the current in the rails, at any given instant flows in opposite directions in the two rails, separate car-carried receiving means with one over each rail for receiving the energy of said rail currents of different frequencies, decoding means on the car including a primary translating means connected to one of the receiving means and a plurality of other translating means connected to the other receiving means and each arranged in quadrature to the said primary translating means, whereby to be distinctively responsive to energy of each of said currents of different frequencies, and to the phase relation of the two currents in the said separate receiving means to assume distinctive positions, a plurality of indicators of varying restrictivenesses controlled by the decoding means in its distinctive positions to thereby set up indications varying in restrictiveness, a most restrictive indicator, means biasing the decoding means to a position to control the most restrictive indicator to give a most restrictive indication, control contacts for said plurality of. other translating means, said decoding means responding to rail current flowing through the rails in the same direction at any given instant, or in one rail only, and of any frequency, to move said control contacts so as to cause the display of the most restrictive indication.

9. In a train control system, in combination, trackway apparatus for placing either one of two currents, of one or the other of two different frequencies as determined by traffic conditions ahead, on the rails in a loop circuit, whereby the current in the rails, at any given instant flows in opposite directions in the two rails, separate car-carried receiving means with one over each rail for receiving the energy of said rail currents of diiferent frequencies, decoding means on the car including a primary translating means connected to one of the receiving means and a plurality of other translating means connected to the other receiving means and each arranged in quadrature to the said primary translating means, whereby to be distinctively responsive to energy of each of said currents of different frequencies, and to the phase relation of the two currents in the said separate receiving means to assume distinctive positions, a plurality of indicators for indicating clear, caution and danger and controlled by the decoding means in its distinctive positions to thereby set up corresponding indications, means biasing the decoding means to a position to control the danger indicator to give a danger indication, control contacts for said plurality of other translating means for setting up clear and caution indications in response, respectively, to energy of one of said frequencies, and to energy of the other of said frequencies, said decoding means responding to rail current flowing through the rails in the same direction at any given instant, or in one rail only, to cause the display of the danger indication.

WADE H. REICHARD. CHARLES S. BUSHNELL.

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