US20070040069A1

US20070040069A1 - Railroad system and method for determining information about a railroad system

Info

Publication number: US20070040069A1
Application number: US11/504,800
Authority: US
Inventors: Gerhard Wilms
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2005-08-16
Filing date: 2006-08-15
Publication date: 2007-02-22
Also published as: DE102005039420A1

Abstract

A railroad system and a method for determining information about the railroad system that has at least one track which is formed from at least two rails, on which railroad vehicles move along the rails, having a device which is electrically connected to the two rails at a connecting point and injects an electric current into the rails. In order to allow information to be determined about the railroad system with little effort, in particular the location of a broken rail and/or the direction of travel of a railroad vehicle, a profile of the current or the corresponding profile of the effective track impedance is detected, while a railroad vehicle is approaching, passing, and moving away from the connecting point. At least one railroad system information item is derived on the basis of the profile.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2005 039 420.5, filed Aug. 16, 2005; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a railroad system and to a method for determination of information about a railroad system. The railroad system has at least one track, which is formed from at least two rails, on which railroad vehicles move along the rails. The system further has a device which is electrically connected to the two rails at a connecting point and which injects an electric current into the rails. The invention also pertains to a method for determining information, in particular about a broken rail, in the railroad system.
Railroad systems are generally known, for example for passenger trains. These generally have a plurality of tracks, which are formed from two rails. Signals to control the trains are arranged along the tracks. The signals are driven by safety devices, with respectively adjacent safety devices interchanging control information. This interchange takes place via the rails by means of coded data in the form of electrical current pulses, for which purpose the safety devices are electrically connected to the two rails.
Furthermore, U.S. Pat. No. 5,769,364 discloses a diagnosis device in which two devices, in particular safety devices, interchange information in the form of pulses via the rails, with the two devices alternately transmitting and receiving the information. In this case, the voltage which is applied to the two rails by the one device, the current which is produced by it and the voltage which results from it at the other device are in each case measured. These measurements are used to determine whether the rails are broken.
One disadvantage in this case is the relatively high degree of complexity and the lack of any capability to localize the broken rail.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a railroad system and a method for determination of information about the railroad system, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and, by means of which the information can be determined with little complexity, in particular the information about the location of a broken rail and/or the direction of travel of a railroad vehicle.
With the foregoing and other objects in view there is provided, in accordance with the invention, a railroad system, comprising:
a track formed of at least two rails configured to support railroad vehicles moving thereon;
a device electrically connected to the rails at a connecting point and configured to inject an electric current into the rails;
means associated with the device for detecting a profile of the current or a corresponding profile of an effective track impedance while a railroad vehicle is approaching the connecting point, passing the connecting point, and moving away from the connecting point; and
means associated with the detecting means for deriving at least one railroad system information item on the basis of the profile.
In accordance with a further feature of the invention, the deriving means is configured to determine a broken rail on the basis of the profile.
With the above and other objects in view there is also provided, in accordance with the invention, a method of determining information in a railroad system having a track formed with at least two rails and having railroad vehicles moving along the rails. The method comprises:
providing a device with an electrical connection to a connecting point at the rails of the track;
injecting an electric current into the rails at the connecting point;
detecting a profile of the current, or a corresponding profile of an effective track impedance, while a railroad vehicle is approaching the connecting point, passing the connecting point, and moving away from the connecting point; and
deriving at least one railroad system information item on the basis of the profile.
In other words, with regard to the railroad system and with regard to the method, the solution provides for the profile of the current or the corresponding profile of the effective track impedance to be detected, while a railroad vehicle is approaching the connecting point, passes it and moves away from it again, and for at least one railroad system information item to be derived on the basis of the profile.
In accordance with an added feature of the invention, the railroad system information item is at least one of a state of the track and a direction of travel of the railroad vehicle. In accordance with another feature of the invention, deriving means is configured to determine the state of the track state on the basis of noticeable rates of change of the profile. The changes are considered noticeable when they are outside a predetermined tolerance band. In the alternative, or in addition, the changes are considered noticeable when they exceed a predetermined value within a predetermined time interval.
In other words, the railroad system information preferably includes the track state and/or the direction of travel of the railroad vehicle.
It is technically simple for the track state to be derived on the basis of noticeable rates of change of the profile.
One simple criterion for noticeable changes is when the changes are outside a predetermined tolerance band.
Simple noticeable changes occur when they exceed a predetermined value within a predetermined time interval.
In the simplest case, a broken rail can be determined on the basis of the profile.
The location of the broken rail is determined with little effort on the basis of the profile.
In order to form a reference value with little effort, it is proposed that the profile in the area of the connecting point have an essentially constant value as a maximum value, and for this constant value to be used as a reference value.
The accuracy can be increased if the device is arranged in the area, or in the vicinity of an isolating abutment of the rails.
In order to make integration in existing railroad systems easier, it is proposed that the device transmit electrical current pulses via the rails, and that the profile correspond to the amplitudes of the current pulses in the form of an envelope curve.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a railroad system and method for determination of information about a railroad system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified plan view of a track section of a railroad system;
FIG. 2 is a profile of the current plotted against the time for a passing railroad vehicle;
FIG. 3 is a profile similar to FIG. 2, with a railroad vehicle passing in the opposite direction of travel;
FIG. 4 is a profile similar to FIG. 2 with a tolerance band; and
FIG. 5 is a view of a track section similar to FIG. 1, with two devices for transmission of current pulses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a track section 1 of a railroad system which is formed from two parallel running rails 2.
A schematically illustrated railroad vehicle 3 is moving along the rails in the direction of the arrow 4. Only two wheels 6 of the railroad vehicle 3 are illustrated in FIG. 1. The wheels 6 are rotatably mounted at the ends of a wheel axle 5. It will be understood that the railroad vehicle 3 in reality has a plurality of wheel axles 5. A device 8 is electrically connected by way of lines 9 to the two rails 2 at a connecting point 7. In order to simplify the illustration, the lines 9 of the connecting point 7 are shown separated from one another in FIG. 1;. In practice, there is no such separation, that is to say the connections of the lines 9 are located approximately at the same level, seen in the longitudinal direction of the rails 2. The rails 2 of the track section 1 each have isolating abutments 9 a, 9 b at the same level in FIG. 1. The device 8 injects a current I into the rails 2 via a voltage U, with the circuit being short-circuited by the railroad vehicle 3 (axle 5 with wheels 6).
With reference to FIG. 1, the railroad vehicle 3 is moving along the rails 2, moving from left to right over the connecting point 7. This is associated with a change in the effective track impedance as the vehicle approaches the connecting point 7.
FIG. 2 shows the profile 10 of the current I plotted over the time t as the railroad vehicle 3 passes by. As can be seen from FIG. 2, the profile 10 of the current I in this case exhibits noticeable rates of change. For example, on passing over the isolating abutments 9 a, the current I changes suddenly from the quiescent current IR to the current IB (time t1). From there, the current increases continuously to the time tx1, while it reaches its saturation current IK at tx1. When passing over the isolating abutments 9 b at the time ty1, the current I returns to the quiescent current IR. FIG. 2 shows a typical profile 10 for a railroad vehicle 3 which is moving from left to right (as shown in FIG. 1), without there being any broken rail or the like.
On the basis of Ohm's law, the profile 10 of the current I corresponds closely with the profile 10 of the effective track impedance.
The profile 10 can be used to obtain information (railroad system information) as to the direction of travel in which the railroad vehicle 3 is moving.
The breakage of one of the rails 2 virtually always occurs only when a railroad vehicle 3 is moving over the rails 2, so that at least one wheel axle 5 will always have passed over the broken point in the direction of the connecting point 7. In a corresponding manner, the profile 10 shown in FIG. 2 changes only to the extent that the current I falls below the quiescent current IR to the rest or residual current IRB on passing over the isolating abutments 9 b, as is shown in FIG. 2.
FIG. 3 shows the profile of the current I plotted against the time t for a railroad vehicle 3 passing in the opposite direction of travel. In contrast with FIG. 2, the current drop below the quiescent current IR to the residual current IRB now occurs when the last wheel axle 5 of the railroad vehicle 3 has passed over the break in the direction of the isolating abutments 9 a. In this case, the break also results in the residual current IRB being below the quiescent current IR. At the same time, it is possible to locate the break on the basis of the profile 10.
There should expediently be two devices 8, arranged in the area of the abutment points 9 a, 9 b, because of the asymmetry (see FIG. 5).
FIG. 4 in each case shows a dashed line 11 following a typical profile 10 a above and below the typical profile 10 a. The two lines 11 form a tolerance band 11 a. Noticeable changes in a profile 10 occur whenever a determined profile 10 is outside the tolerance band 11.
A noticeable change in the current I also occurs when a change exceeds a predetermined value within a predetermined time interval. A profile that has been normalized with respect to the current IK can also be used for evaluation purposes, with the current IK expediently being used as a reference value at the same time.
FIG. 5 illustrates a track section 1, which corresponds to that in FIG. 1. In contrast with FIG. 1, there are two protection devices 12, which are connected via connections 13 to railroad signaling devices 14 that control the railroad vehicles 3 moving along the rails 2. The protection devices 12 each include a device 8 which is connected to the rails 2 in the area of the isolating abutments 9 a, 9 b. The devices 8 operate as transceivers, which transmit coded data via the rails 2 in the form of electrical current pulses IP, with one of the two adjacent devices 8 in each case transmitting, and the other device 8 receiving, alternately.
Only two of these current pulses IP are illustrated schematically in FIG. 2 (somewhat broader in order to illustrate them better). A voltage pulse is applied by the transmitting device 8 to the rails 2 for each current pulse IP. As can be seen from FIG. 2, the profile 10 of the current I in the case of current pulses IP is the envelope curve of the current pulses IP.
The current pulses IP may, of course, be not only current pulses IP of coded data which are present in any case, but also general current pulses IP which are designed such that it is possible to determine the track impedance on the basis of the profile 10 or of the envelope curve.

Claims

1. A railroad system, comprising:

a track formed of at least two rails configured to support railroad vehicles moving thereon;

a device electrically connected to said rails at a connecting point and configured to inject an electric current into said rails;

means associated with said device for detecting a profile of the current or a corresponding profile of an effective track impedance while a railroad vehicle is approaching said connecting point, passing said connecting point, and moving away from said connecting point; and

means associated with said detecting means for deriving at least one railroad system information item on the basis of the profile.

2. The railroad system according to claim 1, wherein the railroad system information item is at least one of a state of the track and a direction of travel of the railroad vehicle.

3. The railroad system according to claim 2, wherein said deriving means is configured to determine the state of the track state on the basis of noticeable rates of change of the profile.

4. The railroad system according to claim 3, wherein changes are considered noticeable when the changes are outside a predetermined tolerance band.

5. The railroad system according to claim 3, wherein changes are considered noticeable when the changes exceed a predetermined value within a predetermined time interval.

6. The railroad system according to claim 1, wherein said deriving means is configured to determine a broken rail on the basis of the profile.

7. The railroad system according to claim 6, wherein said deriving means is configured to determine a location of a break in the rail on the basis of the profile.

8. The railroad system according to claim 1, wherein the profile in the area of the connecting point is set such that it has a substantially constant value as a maximum value, and the value is used as a reference value.

9. The railroad system according to claim 1, wherein said rails are formed with an isolating abutment and said device is disposed in a vicinity of said isolating abutment.

10. The railroad system according to claim 2, wherein said device is configured to transmit electrical current pulses with amplitudes via said rails, and the profile corresponds to the amplitudes of the current pulses in the form of an envelope curve.

11. A method of determining information in a railroad system having a track formed with at least two rails and having railroad vehicles moving along the rails, the method which comprises:

providing a device with an electrical connection to a connecting point at the rails of the track;

injecting an electric current into the rails at the connecting point;

detecting a profile of the current, or a corresponding profile of an effective track impedance, while a railroad vehicle is approaching the connecting point, passing the connecting point, and moving away from the connecting point; and

deriving at least one railroad system information item on the basis of the profile.

12. The method according to claim 11, which comprises determining a broken rail as the railroad system information item.

13. The method according to claim 11, wherein the railroad system information is at least one of a track state and a direction of travel of the railroad vehicle.

14. The method according to claim 13, which comprises deriving the track state on a basis of noticeable rates of change of the profile.

15. The method according to claim 14, which comprises characterizing changes as being noticeable when the changes are outside a predetermined tolerance band.

16. The method according to claim 15, which comprises characterizing changes as being noticeable when the changes exceed a predetermined value within a predetermined time interval.

17. The method according to claim 12, which comprises determining a location of a break in the broken rail on the basis of the profile.

18. The method according to claim 11, which comprises setting the profile in the area of the connecting point to have a substantially constant value as a maximum value, and using the value as a reference value.

19. The method according to claim 11, which comprises placing the device in an area of an isolating abutment of the rails.

20. The method according to claim 11, which comprises transmitting with the device electrical current pulses via the rails, and defining an envelope curve as the profile corresponding to the amplitudes of the current pulses.