US3891168A

US3891168A - Apparatus for safeguarding the spacing between successive bodies, especially vehicles on a track

Info

Publication number: US3891168A
Application number: US412254A
Authority: US
Inventors: Peter Kraus
Original assignee: Messerschmitt Bolkow Blohm AG
Current assignee: AEG Schienenfahrzeuge Nahverkehr und Wagen GmbH
Priority date: 1972-11-09
Filing date: 1973-11-02
Publication date: 1975-06-24
Anticipated expiration: 1992-06-24
Also published as: IT999253B; CA1003940A; JPS50799A; DE2254799C3; AT331854B; JPS5628751B2; FR2206225B1; NL7313942A; FR2206225A1; DE2254799B2; ATA928873A; SE411331B; GB1448719A; DE2254799A1

Abstract

The present safeguarding apparatus assures that successive bodies, such as vehicles on a track, will not bump into each other even where the vehicles must pass through a track junction to travel in different directions. The bodies are equipped with transmitter and receiver means and the tracks are equipped with first and second attenuated electrical conductor means for transmitting signals from a preceding body to a succeeding body to measure the spacing between these bodies. Said first and second attenuated electrical conductor means are interconnected with each other by further conductor means at least in the area of said junction in such a manner that feeding a signal into the first or second electrical conductor at any given point in said junction area corresponds substantially to feeding said signal into the respective other of said first or second electrical conductor means at the respective opposite point.

Description

United States Patent 11 1 Kraus June 24, 1975 [75] Inventor:

[73] Assignee: Messerschmitt-Boelkow-Blohm GmbH, Munich, Germany [22] Filed: Nov. 2, 1973 [21] Appl. No.: 412,254

Peter Kraus, Munich, Germany [30] Foreign Application Priority Data Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Reinhard J. Eisenzopf Attorney, Agent, or Firm-W. G. Fasse; W. W. Roberts 57 I ABSTRACT The present safeguarding apparatus assures that successive bodies, such as vehicles on a track, will not bump into each other even where the vehicles must pass through a track junction to travel in different directions. The bodies are equipped with transmitter and receiver means and the tracks are equipped with first and second attenuated electrical conductor means for transmitting signals from a preceding body to a succeeding body to measure the spacing between these bodies. Said first and second attenuated electrical conductor means are interconnected with each other by further conductor means at least in the area of said junction in such a manner that feeding a signal into the first or second electrical conductor at any given point in said junction area corresponds substantially to feeding said signal into the respective other of said first or second electrical conductor means at the respective opposite point.

10 Claims, 5 Drawing Figures APPARATUS FOR SAFEGUARDING THE SPACING BETWEEN SUCCESSIVE BODIES, ESPECIALLY VEHICLES ON A TRACK BACKGROUND OF THE INVENTION The present invention relates to an apparatus for safeguarding the spacing between successive bodies, specially vehicles on a track, for example, in a local transit system or in metropolitan railroad. In the past, ever increasing demands have been made for a higher conveying performance as well as for an efficient cruising or schedule speed. However, these two conditions can be satisfied simultaneously only if a very high traffic density is permitted in the individual track section. As a result, the safeguarding of the spacing between successive vehicles becomes especially important.

A high traffic density calls for sequencing durations between adjacent cars which last only a few seconds in transit systems employing so called individual vehicles. However, sequencing durations of a few seconds cannot be handled with the necessary spacing safety by conventional means such as a spot light signal or a so called linear influencing system. These conventional means are unsatisfactory because each moving body or rather vehicle must control its speed and its spacing from the preceding vehicles in response to the speed of the preceding vehicle where the above mentioned short sequencing durations are to be maintained. A basic requirement for this type of operation calls for continuously informing each vehicles with regard to its spacing from the respective preceding vehicle. Stated differently, supplying such information only at predetermined reference points will not be sufficient. For this purpose US. patent application 277,783 filed Aug. 3, 1972,Peter Kraus et al. now US. Pat. No. 3,836,770, discloses a transit system in which each vehicle is equipped with a transmitter means and with a receiver means. Each receiver has a predetermined input sensitivity. Further, in said previous system, the tracks are equipped with electrical signal-conveying means providing a special predetermined attenuation in such a manner that a signal emanating from the transmitter means with a defined amplitude will be received by the receiver means of the next following vehicle as an indication of the spacing between the two vehicles because the signal amplitude will decrease in a defined manner as a function of the spacing from the transmitter due to said attentuation. Preferably, the signal conveying medium is a homogenous, electrical conductor means which is attenuated to such an extent that the amplitude of a signal coupled into the conductor means by a signal transmitter diminishes in a measurable manner already after passing through a short length of said conductor means, for example, after one meter. Therefore, it is possible to use the amplitude of a signal at the location of a receiver means as a measure for the spacing between the transmitter and receiver means. that is between the two vehicles.

ln thesystem according to the above German patent publication, each vehicle receives continuously through its receiver having a defined input sensitivity, information regarding its spacing from the respective preceding vehicle as long as the transmitter of the preceding vehicle feeds a signal of a defined amplitude into the attenuated electrical conductor means.

ln a system such as described in the above German patent publication, problems arise where the track comprises a junction with track branches extending in different directions since it is necessary to avoid collisions between a following vehicles and a preceding vehicle under two different aspects. First, collisions must be avoided between adjacent vehicles, both of which are intended to travel in the same branch direction. Second, collisions must also be avoided between a following and a preceding vehicle where the preceding vehicle is intended to travel in another branch direction but is still within or ahead of a junction departure area. Thus, the measurements of the spacing between adjacent bodies or vehicles, possibly in combination with information regarding the speed of the vehicles or bodies, must be employed to control the spacing between adjacent vehicles to avoid both of the mentioned collisions.

Another problem is posed in connection with the system described in the above German patent publication by the need for avoiding that a third vehicle, which is still within the junction, but which has passed the junction departure area, influences, for example by slowing down, the measuring of the spacing or the safeguarding of the spacing between two vehicles which are intended to travel in the same direction.

The following text will refer to vehicles" generally. However, it is to be understood that the present diclosure applies equally to any type of body moving along a track.

OBJECTS OF THE INVENTION In view of the above, it is the aim of the invention to achieve the following objects singly or in combination:

to solve the above outlined problems, more specifically to assure the safeguarding or proper spacings between ajacent vehicles moving along a track, even when the track comprises a junction;

to provide a system in which a succeeding vehicle on a track receives information regarding its spacing from two vehicles ahead of it on a track including a junction, whereby the spacing infonnation shall be supplied continuously with regard to a preceding vehicle travelling in the same direction as the following vehicle whereas the spacing information with regard to a preceding vehicle travelling in a different direction shall be supplied only as long as said preceding vehicle travelling in the different direction has not yet passed completely through a junction departure area;

to permit the stopping of a vehicle after it has passed a junction departure area without causing by such stopping the deceleration of a vehicle passing through the junction in another direction;

to avoid a collision of vehicles in the junction independently of the direction of travel which has been selected for any particular vehicle; and

to provide a system in which the transmitter output power and the receiver input sensitivity is variable in response to the speed of the respective vehicle.

SUMMARY OF THE INVENTION According to the invention there is provided an apparatus for safeguarding the spacing between successive bodies, especially vehicles on a track including a track junction with track branches extending into different directions wherein each vehicle is provided with transmitter and receiver means for measuring the spaceing between adjacent vehicles. Along both sides of said track junction there is arranged a respective homogenous, electrical conductor providing a special attenuation, wherein coupling means are provided for coupling the transmitter and receiver means of the individual vehicles with the conductor extending in the direction in which the respective vehicle is intended to travel, and wherein further conductor means interconnect the attenuated, homogenous conductor means extending along the track branches, said further conductor means extending at least from the beginning of the junction to the end of a junction departure area. Preferably, the further conductor means are arranged at uniform intervals relative to each other. The further conductor means may comprise galvanic connections arranged at such narrow intervals relative to each other that the coupling of a signal into one of the first mentioned conductors at any point therealong corresponds substantially to the coupling of the signal into the other of the first mentioned conductors at the respective opposite point. Preferably, the narrow intervals between adjacent further conductor means are used up to the end of the junction departure area.

In the arrangement according to the invention one attenuating conductor means will thus be provided for each track or branch, that is for each direction. Further, upon reaching the junction the transmitter and receiver means of a vehicle will be coupled only to that attenuating conductor which extends in the direction in which the vehicle is intended to travel in order to receive signals from a preceding vehicle intended to travel in the same direction for the measuring or controlling of the spacing of the following vehicle from the preceding vehicle. However, due to the interconnection which is provided according to the invention between the two attenuating electrical conductor means, the following vehicle is also capable to receive signals from a preceding vehicle which is intended to travel in a different direction, even though the receiver of the vehicle has been coupled to but one of said attenuating conductor means. Accordingly, collisions with such a vehicle intended to travel in another direction will also be avoided as long as there is a danger of such a collision, that is, as long as the preceding vehicle travelling in the other direction has not yet cleared the junction departure area. After a vehicle travelling in another direction has passed the junction departure area, it is not capable of influencing the travel of the following vehicle which is intended to travel in the opposite direction. This feature of the invention has the advantage that a traffic jam in a track branch downstream of a junction departure area will not affect the flow of traffic, the vehicles of which are intended to travel along the opposite branch of the junction.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 illustrates a schematic plan view of a track section with a junction and two track branches wherein an electrical conductor extends along each rail of the track and into the respective track branch;

FIG. 2 illustrates a sectional view through one of the electrical conductor means extending along the rails of FIG. 1, whereby the conductor means is arranged in the gap between two U-shaped iron cores of a coupling means, such as a coupling coil;

FIG. 3 illustrates a perspective view of a section of one of the attenuating electrical conductor means used in FIG. 1;

FIG. 4 is a simplified plan view of a track and junction illustrating the interconnection between the electrical conductor means extending along the rails as illustrated in FIG. 1; and

FIG. 5 is a schematic plan view similar to that of FIG. 1 but illustrating amplifier means interconnecting the attenuating electrical conductor means as well as simulating circuit means interconnecting certain of the amplifiers with each other.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS FIG. 1 illustrates three

vehicles

1, 2, and 3 which constitute so called individual transport facilities of a local transit system. These vehicles travel automatically and without stopping between a point of departure and a point of arrival. These

vehicles

1, 2 and 3 cannot pass each other as long as the vehicles are on the same course or track. For this purpose, it is possible to use one tracer guide for the vehicles, for example in the form of a track, rail or the like. The

vehicles

1, 2 and 3 are located on the

track section

4, 5 and 6 interconnected by a junction. The directions of vehicle advance are indicated by the arrows 7, 8 and 9. Thus, the vehicles travel through the junction in the direction of a decentralization whereby the last vehicle 3 is intended to make a left turn when passing through a junction departure area 10 which is marked by a broken line circle in FIGS. 1, 4 and 5 of the drawings. By making the left turn, the vehicle 3 will pass from the track section 4 into the track section or branch track 5. For the illustrated vehicle sequence such a left turn by the vehicle 3 is possible only when the vehicle 2, which is intended to make a right turn into the branch track 6, has passed through the junction departure area 10. Stated differently, the vehicle 2 must have completely cleared the railway loading gauge of the

track sections

4 and 5. As illustrated in FIG. 1, vehicle 2 has not yet completely cleared the

track sections

4 and 5. Accordingly, in order to avoid a collision between the vehicle 3 and the vehicle 1, as well as between the vehicle 3 and the vehicle 2, the vehicle 3 must receive information regarding its spacing relative to both vehicles ahead of it on the left track branch 5 and on the right track branch 6. The travel, or rather the speed of the vehicle 3 must be determined accordingly as long as the vehicle 2 has not yet completely cleared the junction departure area 10. As soon as the vehicle 2, making a right turn, has cleared the junction departure area 10, the last vehicle 3 shall receive information only regarding its spacing relative to the vehicle 1, which has made a left turn corresponding to the turn intended to be made by the vehicle 3. In other words, the speed or travel of the vehicle 3 shall depend only on the speed or travel of the vehicle 1 after the vehicle 2 has cleared the area 10. The manner in which all of these conditions may be met shall now be elucidated in more detail.

As illustrated .in FIG. 1 all

vehicles

1, 2 and 3 are equipped with transmitter means 11 and receiver means 12. These transmitter and receiver means are inductively coupled with the attenuating first and second electrical conductor means 13 and 14. The electrical conductor means 13 extend along the

tracks

4 and 5 whereas the electrical conductor means 14 extend along the tracks 4 and 6. These electrical conductor means 13 and 14 are of the same construction and provide a predetermined attenuation along their length as will be described in more detail below. The transmitter means 11 may, for example, comprise known generators for producing a high frequency alternating current. For example, transistor generators may be suitable for this purpose. The transmitter 11 may be connected by means of a selector switch (not shown) either to a couplingcoil 11 arranged on the left longitudinal side of the vehicle or to the coupling coil 11'' arranged on the right longitudinal side of the

respective vehicle

1, 2 and 3.

The receiver means 12 may each comprise a conventional transistor amplifier which is also connectable by means of a selector switch (not shown) either with a coupling coil 12 arranged on the left longitudinal side of the respective vehicle or with a coil 12" arranged on the right longitudinal side of the respective vehicle.

All of the coupling coils 11', 11" and 12', 12" which are provided for the transmitter means 11 and for the receiver means 12, are of the same construction with the possible exception of the number of turns. The construction of these coils is schematically shown in FIG. 2 whereby only one of the coils l l is illustrated in connection with one of the electrical conductor means 13 as mentioned above. The winding 15 of the coil is symmetrically distributed over two U-shaped iron cores 17 having the same dimensions and defining an air gap 16. The iron cores 17 are arranged symmetrically relative to the conductor 13 which extends longitudinally through the air gap 16. In the illustrated arrangement or structure of the coils ll, 11", 12' and 12" the magnetic'stray flux or leakage will be small relative to the effective flux in the air gaps 16 or in the iron cores 17. In addition, the magnetic flux will be homogenized in the air gaps. This has the advantage that the efficiency of the transmitter means 11 is at a maximum whereas the sensitivity of the receiver means 12 relative to magnetic stray fields will be at a minimum.

FIG. 2 further illustrates that the electrical conductor 13 and thus the electrical conductor 14 comprises three parallel conductor members 18. The spacings between the center conductor member and the two outer conductor members are the same. Such a symmetric conductor 13 has a substantially heigher stability against disturbing effects than conventional twin conductors.

Since it is not possible to completely avoid that the vehicles I, 2 and 3 and thus the respective coils ll, 11'', 12', 12" make lateral movements relative to the conductors l3, l4=while traveling along the track, the width of the pole pieces 19 of the iron cores 17 is smaller than the spacing between the center conductor member 18 and the outer conductor members 18 or the electrical conductor means. However, the width of the conductors l3, 14 is larger than the width of the iron cores 17. This construction has the advantage that both conductor loops 20 are uniformly exposed to the magnetic flux even if the coils 11', 11", 12' and 12" should be laterally displaced relative to the conductor means I3, 14. The sliding of the conductor means 13 and 14, along the pole pieces 19, for example due to lateral back and forth movement of the

vehicles

1, 2, and 3, may be prevented by making the air gaps 16 sufficiently influence on the coupling between the coils and the

respective conductor

13 or 14 if the coils ll, 11', 12', and 12" are constructed as described above, namely, when the coils comprise two windings 15 which are symmetrically distributed on two iron cores 17.

As mentioned, both conductor means 13 and 14 as shown in FIG. 1 are of the identical construction. As may be seen from FIG. 3 the individual conductor members 18 are so called flat strip copper conductors or the like which are embedded together with a conducting foil 21 in a sheeth 22 of synthetic material. The conducting foil 21 may, for example, comprise a carbon coated fleece of synthetic material. The individual conductor members 18 are connected with each other in a conducting manner along their entire length by the conducting foil 21. However, the conductivity of this cross connection is substantially smaller than that of the conductor members 18. The combination of the substantial ohmic cross leakage with the longitudinal or series impedance of the conductor members 18 provides the strong attenuation along the conductor means 13 and 14 mentioned above. The amplitude of a signal travelling along such especially attenuated homogeneous conductor means diminishes in a measurable manner already after having passed through a short length of the conductor means, for example after one meter. The signal amplitude of the signals which have been coupled into the conductor means through the coils l l large. S'uch'back and forth movements are without any or 11" diminishes in accordance with an exponential function having a negative exponent. Accordingly, the amplitude of the signal at any random point along the conductor means is a measure for the spacing between this random point and the respective transmitter means 11 or rather the respective coupling coil 1 l or 1 1''. As a result, the last vehicle 3, for example, is able to receive through its receiving means 12 having a defined input sensitivity, information regarding its spacing relative to the vehicle 1 moving along the left track branch 5. Such information is supplied as long as the transmitter means 11 of the vehicle 1 couple a high frequency alternating current signal into the conductor means 13 through the coil 11' and as long as the conductor means 13 are coupled to the coil 12 of the receiving means 12 of the last vehicle 3.

Where, due to a high traffic density, the spacing between adjacent vehicles is extremely small, the information regarding such spacing alone is not sufficient to prevent a collision between adjacent vehicles. Therefore, according to the invention the transmitting power of the transmitter means 11 and the input sensitivity of the receiver means 12 is variable as a function of the speed of the respective vehicle. The transmitting power of each transmitter means 11 reaches its maximum when the

respective vehicle

1, 2 or 3 is stopped. When the vehicle travels at its maximum speed the transmitting power is at its minimum. Contrary thereto, the input sensitivity of each receiving means 12 is at its minimum when the vehicle is stopped and at its maximum when the vehicle travels at its maximum speed. To this end, the transmitter means 11 and the receiver means 12 of each vehicle may be controlled by a voltage which may be derived for example from a generator voltage produced by a generator driven by a wheel of the vehicle.

It will be appreciated that due to the above feature, the last vehicle 3 will receive an information for the control of its travel and braking action as long as the transmitter means 11 of the vehicle 1 travelling on the left branch track transmits a signal. The received signal will depend from the speed of the receiving vehicle and from the speed of the preceding transmitting vehicle and from the spacing between the two vehicles. Ac cordingly, the received information is suitable for controlling the travel characteristics of the receiving vehicle 3 in such a manner that a collision with the transmitting vehicle 1 is impossible. To this end, the vehicle drive means (not shown) are provided with a control member to which the information signals received by the vehicle 3 are supplied as a reference input valve. The control member also receives the above mentioned generator derived control voltage. The reference value and the control voltage are combined with each other in such a manner that an automatic braking action is applied to the vehicle when the control voltage exceeds the reference voltage. Accordingly, the fact that the control value exceeds the reference value is always an indication that the receiving vehicle 3 has a higher speed than the preceding transmitting vehicle 1 and/or that the spacing between the two vehicles is too small for the speed difference.

In the light of the foregoing description it will be appreciated that the travel characteristics of the last vehicle 3 are determined by the travel characteristics of the vehicle 1 travelling ahead of the vehicle 3 along the left track branch 5 whereby the mentioned transmitter means 11 and the receiver means 12 with their respective coils l l and 12' are employed in combination with the attenuated electrical conductor means 13. In order to assure that the last vehicle 3 will also not collide with the vehicle 2 which is still in the junction departure area but which is intended to make a right turn along the track branch 6, the electrical conductor means 13 extending in the direction of travel of the vehicles l and 3, and the electrical conductor means 14 extending in the direction of travel of the vehicle 2, are interconnected with each other by galvanic connections 23. Preferably, these galvanic connections 23 which constitute further conductor means are arranged at uniform intervals relative to each other and extend from the beginning B of the junction to the end E of the departure area 10 as schematically illustrated in FIG. 4. The intervals between adjacent connections 23 may, for example, have a width of a few centimeters. Due to these interconnections 23, the coupling of a signal into one of the conductor means 13 or 14 at any random point A corresponds substantially to the direct coupling of the signal into the respective

opposite conductor

14 or 13 at the corresponding opposite point A. As a resuit, as long as the vehicle 3 travels between the beginning B of the junction and the end E of the junction departure area 10 its receiver coils 12 will also receive a signal from the vehicle 2 making a right turn, which signal is coupled to the conductor means 14 by the respective coil 11 of the transmitter means 11 of the vehicle 2. This is so even though the coil 12' is coupled with the conductor means 13. This signal at the position of the coil 12 of the receiving means 12 of the last vehicle 3 corresponds in its amplitude and phase substantially to the signal which would be received if the receiver means 12 were coupled with its coil 12" with the conductor means 14. Therefore, the vehicle 3 will be controlled or react in such a manner as if the vehicle 2, making a right turn, where in front of the vehicle 3 and travelling in the same direction as is intended for the vehicle 3. If the spacing between the

vehicles

2 and 3 is too small, that is if the vehicle 3 cannot pass through the junction departure area 10 without interferrence by the vehicle 2, the vehicle 3 will be automatically subjected to a braking action due to the signal received from the vehicle 2. However, this is possible only as long as the vehicle 2 intending to make a right turn has not yet completely cleared the junction departure area 10. After such clearing is completed, the vehicle 2 can transmit signals only to vehicles following in the same branching direction since the interconnections 23 between the conductor means 13 and 14 do not extend beyond the end E of the junction departure area 10. In other words, once the vehicle 2 has cleared the area 10 only vehicles which are coupled with their receiver coils 12" to the conductor means 14 can receive signals from the vehicle continuing its travel on the track branch 6. This feature of the invention has the advantage that, for example, vehicles which have passed the junction departure area 10 after having made a right turn, can stop without causing a braking action in vehicles which negotiate the junction departure area in a left turn.

In view of the foregoing description of the apparatus according to the invention it will be appreciated that a collision between a following vehicle and a preceding vehicles is definitely prevented regardless of which direction any individual vehicle is intended to take. Upon reaching the junction it is merely necessary that the transmitter means 11 and the receiver means 12 of the vehicles are coupled to the conductor means 13 or 14 which extend in the direction of travel in which the respective vehicle is intended to proceed. A respective actuation of the selector switch, which is arranged between the transmitter means 11 and the receiver means 12 and the respective coils ll, 11" or 12, 12", may, for example, be accomplished in connection with the steering mechanism of the vehicles. Accordingly, the selector switch will be actuated in response to the operation of the steering mechanism for a left or right turn. Suitably, all of the transmitter and receiver means of the vehicles are coupled only with one common conductor means 13 or 14 prior to entering into the junction.

Since the propagation of a signal emanating from a transmitter means 11 is symmetrical in both directions of a conductor means 13 or 14, that is, the signal also propagates in the direction of vehicle advance as indicated by the arrows 7, 8 and 9, it is possible that a transmitted signal may influence the receiving means 12 of the vehicle from which the signal has been transmitted. in order to avoid such a self influence, so to speak, for example of the receiving means 12 of the last vehicle 3 by a signal emanating from the transmitter means 11 of said vehicle 3, there is provided according to the invention a compensating transmitter means 24 which is arranged between the transmitter means 11 and the receiver means 12 of each

vehicle

1, 2 and 3. This com pensating transmitter means 24 is coupled to the re spective conductor means 13 or 14. The compensating transmitter means 24 correspond in their structure substantially to the transmitter means 11 described above whereby these compensating transmitter means 24 may also be coupled selectively through a selector switch (not shown) either with a coil 24' arranged along the left longitudinal side or with a coil 24" arranged on the right longitudinal side of the

respective vehicle

1, 2 and 3. These

coils

24 and 24" also correspond in their structure and in their arrangement relative to the

conductors

13 or 14 to the coils 11" or 11" of the transmitter means 11 provided for the measuring purposes.

Each compensating transmitter means 24 transmits a signal having an amplitude corresponding to the amplitude of the signal transmitted by the measuring transmitter means 11 of the same vehicle at the location of the compensating transmitter means whereby a phase shift of 180 is provided between the two signals at said location. As a result, the signal of the measuring transmitter means 11 is substantially erased at the location of the compensating transmitter means 24 without substantially influencingthe propagation of this signal in the respective conductor ineans 13 or 14 in the direction toward the next following vehicle. Due to the further conductor means 23 between the conductor means 13 and l4, each compensating transmitter means 24 produces simultaneously a signal in both conductors l3 and 14. Therefore, it is assured that in the area of the conductors 23 a signal from the measuring transmitter means 11 will not substantially propagate beyond the location of a respective compensating transmitter means 24.

Incidentally, the

vehicles

1, 2 and 3 have been omitted in FIGS. 4 and 5 for simplicitys sake and in order to facilitate the illustration of the further conductor means 23.

In the embodiment of FIG. 4, the further conducto means 23 extend directly between the first and second conductor means 13 and 14 galvanically interconnecting these first and second conductor means. In the modification according to FIG. 5, the further conductor means comprise amplifiers or 26 which, for example, may be conventional transistor amplifiers. These amplifiers are used in the further conductors beginning at the junction and extending to the end of the junction departure area 10. The amplifiers 25 permit the transmittal of signals from the left conductor means 13 into the right conductor means 14 as viewed in the direction of vehicle advance. The amplifiers 26 on the other hand, permit the signal transmission in the opposite direction. This is illustrated in FIG. 5 for a short section of the track portion 4. As compared to the arrangement of FIG. 4, fewer further connections are required in the embodiment of FIG. 5. Where amplifiers are used in the further conductor means, the intervals between such further conductor means with amplifiers feeding into the same first or second conductor means 13 or 14 may have a width which is smaller than the smallest possible spacing from center to center between two vehicles immediately following each other. As long as said intervals have the just defined width, it is assured that even where there is a smaller spacing between two vehicles, each of which is intended to turn in a different advance direction, the preceding vehicle will be able to transmit signals to the following vehicle. Suitably the

amplifiers

25 and 26 are operated with a strong negative feed-back and provide an amplification or gain of l In this manner it is assured that the signals appearing at the outputs of the amplifiers 26, which are connected to the conductor means 13, are the same with regard to amplitude and phase position as the signals at the inputs of these amplifiers connected to the conductor means 14. Accordingly, in the arrangement of FIG. 5, the coupling of a signal into one of the

conductors

13 or 14 at the location of an

amplifier

25 or 26 corresponds to directly coupling this signal into the respective other conductor means 14 or 13 at the respective opposite location.

According to the invention, it is assured that a signal transmitted through an

amplifier

25 or 26 can propagate in the

respective conductor

14 or 13 in the direction of vehicle advance only in the limited manner, namely only up to the feed-in point of the

next amplifier

25 or 26 connected to the

same conductor

14 or 13. This is accomplished by simulation circuit means 27 or 28 which are connected in phase opposition between the input and output of the two adjacent amplifiers feeding into the

same conductor

13 or 14 whereby the simulating circuit means constitute a simulation of the respective conductor means 13 or 14 extending between the two amplifiers. Thus, in the embodiment of FIG. 5, the amplifier 26 which is located closer to the junction departure area 10 will, for example, compensates the signal which is present at its feedin point in the conductor means 13 if the other amplifier 26 which is located more remote from the junction departure area 10, feeds a signal into the conductor means 13.

Incidently, it should be mentioned here that in the embodiments of FIGS. 4 and 5, transformer could be connected into the further conductor means interconnecting the conductor means 13 and 14 in order to keep interferring potentials out of the entire system.

Although the invention has been described with reference to specific example embodiments, it is to be understood, that it is intended to cover all modifications and equivalents within the scope of the appended claims.

What is claimed is:

1. An apparatus for safeguarding the spacing between successive bodies, especially vehicles on a track including a track junction with track branches extending into different directions, comprising transmitter and receiver means on each body for measuring the spacing between adjacent bodies, first and second homogenous electrical conductor means having a predetermined signal attenuation, and extending along said track and including respective conductor portions extending along said track branches, coupling means operatively arranged for coupling said transmitter and receiver means to that electrical conductor means and portion thereof extending along the track branch on which the body is intended to travel, and further electrical conductor means interconnecting said first and second conductor means at predetermined intervals therealong, said further electrical conductor means starting at least at the beginning of said junction in the track and continuing to the end of an area where a body leaves the junction, said signal attenuation deter mining the distance of signal transmission.

2. The apparatus according to claim 1, wherein the intervals between adjacent ones of said further conductor means are of uniform width.

3. The apparatus according to claim 1, wherein said transmitter means comprise signal generating means for transmitting signals having a predetermined amplitude, and wherein said receiving means having a predetermined sensitivity.

4. The apparatus according to claim 1, further comprising compensating transmitter means arranged between said transmitter means and said receiver means on the respective body and further coupling means arranged for coupling said compensating transmitter means to the respective one of said first or second electrical conductor means.

5. The apparatus according to claim 1, wherein the intervals between adjacent ones of said further conductor means interconnecting said first and second conductor means have such a narrow width that coupling of a signal into one of said first or second conductors at any point herealong corresponds substantially to directly coupling said signal into the corresponding opposite point along the respective other first or second conductor.

6. The apparatus according to claim 1, comprising amplifier means as part of said further electrical conductor means, wherein those further conductor means the amplifier means of which feed into the same of said first or second electrical conductor means, are spaced from each other at a distance which is smaller than the smallest possible spacing from center to center between immediately adjacent bodies.

7. The apparatus according to claim 6, further comprising simulation circuit means for coupling each amplifier means in phase opposition to at least one other amplifier means feeding into the same first or second electrical conductor means, said simulation circuit means constituting a simulation of the portion of the first or second electrical conductor means extending between the outputs of the coupled amplifier means.

8. The apparatus according to claim 7, wherein said simulation coupling circuit means are arranged to couple each amplifier means to the next adjacent amplifier means feeding into the same first or second electrical conductor means.

9. The apparatus according to claim 7, wherein said simulation coupling circuit means are arranged to couple each amplifier means to at least one other amplifier means arranged in front thereof in the direction of travel of the bodies and feeding into the same first or second electrical conductor means.

10. The apparatus according to claim 1, wherein the intervals between adjacent ones of said further electrical conductor means have a width of a few centimeters.

Claims

1. An apparatus for safeguarding the spacing between successive bodies, especially vehicles on a track including a track junction with track branches extending into different directions, comprising transmitter and receiver means on each body for measuring the spacing between adjacent bodies, first and second homogenous electrical conductor means having a predetermined signal attenuation, and extending along said track and including respective conductor portions extending along said track branches, coupling means operatively arranged for coupling said transmitter and receiver means to that electrical conductor means and portion thereof extending along the track branch on which the body is intended to travel, and further electrical conductor means interconnecting said first and second conductor means at predetermined intervals therealong, said further electrical conductor means starting at least at the beginning of said junction in the track and continuing to the end of an area where a body leaves the junction, said signal attenuation determining the distance of signal transmission.