A train control network is known from [1].

In order to ensure safety during railway operation different railway elements have to communicate with each other. The LZB control center for example com- municates with trains via conductor cable loops [1], To do this, the railway track has to be equipped with conductor cable loops which is involved with considera ble expense. Further, since the conductor loops are located outside they are ex- posed to weather and thus prone to damaging.

Communication between railway elements is also required for controlling train integrity. In order to determine the actual train length it is known to provide a head-of-train device in the railcar and an end-of-train device in the last wagon of a train which communicate with each other via Ethernet, radio communication or cable [2] Yet, with the known methods train integrity can only be determined reliably at straight lines, since the distance between head-of-train device and end-of-train device does not comply with the train length if the train is in a curve.

Object of the invention

It is an object of the invention to provide a train control network, a method for communication and method for controlling train integrity by using the method for communication, which allow reliable information transmission with less expenses.

Description of the invention

This object is solved by a train control network according to claim 1, a method for communication according to claim 9 and a method for controlling train integ- rity according to claim 12.

Accor ing to the invention the first communication element comprises a HF- injector, adapted for injecting HF-signals into the rail, and the second communi- cation element comprises a HF-receiver, adapted for receiving HF-signals transmitted via the rail; an evaluation unit is provided for analyzing the received HF- Signals.

According to the invention the rail is used as a transmission medium for trans- mission of HF-signals between the communication elements. The transmission function via an electromagnetic field which is generated around the rail by means of the HF-injector. I.e the HF-injector is adapted to generate an electromagnetic field around the rail. By means of the inventive signal transmission continuous communication between the communication elements (e.g. trains, field elements etc.) is enabled without installation of additional transmission elements in the field. No data bus is required. The inventive train control network therefore provides a cost-effective communication system. In addition, a low-loss continuous communication can be realized due to the signal transmission by means of HF- signals. The HF-receiver transmits the HF-signals to the evaluation unit for analysis. The evaluation unit is preferably provided with the second communication element, in particular positioned within the second communication element. The evaluation unit may for example be a subsystem of an ETCS on-board. Yet, it is also possi ble to use a remote central evaluation unit to which the received HF-signal or data derived from the received HF-signal are transferred.

Preferably the frequency of the HF-signals is > 1kHz, in particular > 1MHz. Most preferred is the injection of GHz-signals. By providing a high frequency (> 1kHz) of the HF-signals, the losses during transmission can be reduced.

The injected HF-signal comprises an ID for identifying the communication ele- ment to which the HF-injector is assigned (connected to).

In a preferred embodiment the network further comprises a train integrity module for determining train integrity, i.e. the network comprise components (HF- injector, HF-receiver, rail, time basis, evaluator) which interact and are adapted for determining train integrity. In a highly preferred embodiment the HF-signal is a time signal and the train control network comprises a time basis device adapted for providing a common time basis for the HF-receiver and the HF-injector By using a common time basis the runtime of the HF-signals within the rail can be determined. A "time signal" according to the invention is a signal which comprises information about the time, at which the signal has been injected in the rail (timestamp). The time ba sis device can be e.g. a GPS receiver which is in communication with both, the HF-receiver as well as the HF-injector, or clocks which are synchronized with one another. In a highly preferred embodiment the HF-injector is adapted for contact-free in jection of HF-signals Into the rail, in particular for injection via induction or infra sound, and/or the HF-receiver is adapted for contact-free reception of HF-signals from the rail, in particular for reception via induction or infra sound. Contact free injection allows injection of HF-signals without abrasion of contact elements. The communication elements are preferably selected from ; field element (in par ticular element controller of a field element), train, wagon, point, control center.

In a highly preferred embodiment the HF-receiver and the HF-injector are mounted on a train. In this case the communication elements can be wagons of the train. The expression "on a train" means "in" or "at" a train, in particular in vicinity of the rail, e.g. under the train.

In a special embodiment the second communication element is a railcar of a train and the first communication element is the last wagon of a train.

The invention also concerns a method for communication between a first com munication element and a second communication element within a train control network according to one of the preceding claims, wherein a HF-signal is injected into the rail by means of the HF-injector of the first communication element, the injected signal is transmitted via the rail and is received by means of the HF- receiver of the second communication element. It is preferred that the injection and reception are carried out contact-less, in particular via inductive coupling or infra sound.

In order to provide data to the communication elements the HF-signal is elec- tromagnetically modulated. In a preferred variant an unequivocal identification of the first communication element is transmitted with the HF-signai. For example if t e two communication elements are trains, the leading train may sends a HF-signal including a train identifier to the following train. By evaluating the runtime of the HF-signal the following train recognizes the position of the preceding train. The aforementioned method can be advantageously used for controlling train integrity. Therefore, the invention also concerns a method for controlling train integrity by using the aforementioned method, wherein the second communication element is a railcar of a train and the first communication element is the last wagon of a train, the method comprising the following steps: · during an operation mode of the first communication element: continuous- ly injection of HF-signals to the rail, in particular periodically, wherein the HF-signals are time signals;

• analyzing the received HF-signals and determining a train length;

• checking whether the determined train length complies with a target length, in particular the expected length of the train.

The target length is the expected length of the train.

The inventive method allows a safe and direct detection of the relative position of the railcar and the last wagon on the track and/or the distance of the railcar and/or the last wagon to communication elements (e.g. field elements) The de- tection of the relative position can be carried out e.g. by means of kilometer mileage. The inventive method allows easy and precise detection of the train length.

Blocked wheels and lacking GPS-reception (e.g, in tunnels) are no problem if the inventive method is used. Thus a high level of safety can be realized (SIL4).

Preferably the received HF-signals are analyzed by means of an on-board unit (evaluation unit which is installed on board of a train), in particular of an ETCS on-board unit. Thus by means of the inventive method the on-board unit can be provided with safe information concerning train integrity.

In a preferred variant the HF-signals are analyzed by determining a runtime of the HF-signals and using the runtime for determining of the train length. Since the HF-signals are transmitted via the rail the real length of the train can be reliably determined (independently whether the train is located in a curve, in a tunnel or elsewhere) by using the runtime of the HF-signals.

The HF-signals are preferably analyzed by comparing the received HF-signal with a time information of the HF-receiver. Thus, the runtime of the HF-signal can be determined. The same time basis is required for the HF-receiver and the HF- injector.

In case the determined train length does not comply with the target length, it is preferred that a control center is informed and/or an intervention in the operating process is carried out. An intervention can comprise e.g. an emergency brake.

Drawings

The invention is shown in the drawing.

FIG. 1 shows an inventive train control network.

FIG. 2 shows a preferred embodiment of the inventive train control network for train integrity control.

FIG. 3 shows another embodiment of the inventive train control network for communication between a signal and a control center. FIG. 1 shows an inventive train control network with a first communication ele ment I and a second communication element 2 which are in contact or located close to a rail 3 for rail bound vehicles. The first communication element 1 com- prises an first HF-injector 4 for injecting an HF-signa! into the rail 3. For this purpose the first HF-injector 4 is located near the rail 3 (in particular less than 10 cm). The HF-signal is transferred via rail 3 to the second communication element 2. The second communication element 2 comprises an HF-receiver 5 which de tects the HF-signal. According to the invention rail 3 serves not only for guiding a rail bound vehicle but also for transmission of HF-signals. The injection and reception of the HF-signal into/from the rail 3 is preferably carried out contactless as shown in the figures, e.g. via inductive coupling. The inventive train control network further comprises an evaluation unit 6 for evaluating the HF-signal re ceived by the HF-receiver 5. For this purpose HF-receiver 5 transmits the re- ceived HF-signal to evaluation unit 6, which is adapted to receive HF-signals from the HF-receiver 5. The HF-receiver 5 and the evaluation unit are electrically con nected each other.

Fig. 2 shows a highly preferred embodiment of the inventive train control network which can be used for controlling train integrity. The first communication element 1' (here: last wagon 1' of a train 7) is equipped with the first HF-injector 4 which is preferably positioned at the bottom of the wagon 1' for coupling HF- signals into the rail 3. In order to control train integrity the HF-signals injected into the rail 3 are time signals, i.e. signals which contain information concerning the time at which the HF-signal has been injected into the rail 3. The HF-signals are transferred through the rail 3 to the railcar (second communication element 2'), are received by the HF-receiver 5 and transferred to the evaluation unit 6. In the embodiment shown in Fig. 2 the evaluation unit 6 (e.g. an on board unit of an ETCS) is located within the railcar 2. The received HF-signal can thus be eval uated directly within the railcar 2. For controlling train integrity the length of the train 7 has to be determined. According to the invention this is done by evaluating the HF-signai-runtime within the rail 3 between first HF-injector 4 and HF-transceiver 5, For this purpose the evaluation unit 6 and the first HF-injector 4 use the same time basis, which is provided by a time basis device 8. To achieve the required accuracy, e.g. GPS can be used for providing the required time basis. The injected HF-signai com- prises a time information (injection time t ₀ ) which can be read by the evaluation unit 6. The evaluation unit 6 evaluates the runtime by determining the difference of the injection time t ₀ and the reception time ti. Thus the length L of the train can be determined : L=v-(ti-t ₀ ) (v is the propagation speed of the HF-signal within the rail 3). The inventive train control network can also be used for transmitting information between field elements or between an field element 1", 1'" and a control center 2" which is located near the rail 3, as shown in Fig. 3.

In Fig. 3 a railway signal 1" and an axle counter " (first communication ele ments) send HF-signals, (e.g. with information concerning switch state, infor- mation about occupied blocks) via rail 3 to the HF-receiver of the control center 2”. In the shown example the HF-receiver 5 of the control center is located out- side the housing of the control center 2" but is electrically connected with the control center 2”.

The inventive train control network also allows communication between control center 2 and train 7 via the rail 3 (not shown). E.g. control center 2" may send telegrams to the train 7. The telegram may comprise information e.g. concerning movement authority of the train 7. The train 7 may send HF-signals comprising information indicating its configuration, braking capabilities, speed, position etc. to control center 2". In this case both, train 7 and control center 2", act as first communication element as well as second communication element and thus have to be equipped with HF-injector and HF-receiver. Alternatively an HF-transceiver can be installed.

The present invention suggests using a rail of a railway network for communication between communication elements within said railway network, in particular for determining train integrity. Conductor cables for signal transmission and con tinuous connection to location detection devices (e.g. GPS) can be dispensed

List of references signs

1 first communication element

1 first communication element - wagon of a train

1 first communication element - railway signal V" first communication element - axle counter 2 second communication element

2 second communication element - rail car

2 second communication element - control center 3 rail

4 HF-injector

5 HF-receiver

6 evaluation unit

7 train

8 time basis device

Cited references

[1] https://en.wikipedia.org/wiki/Linienzugbeeinflussung

[2] DE 16 163 692.3 (not published)