TRACK CIRCUIT WITH CONTINUED DISTANCE MONITORING AND BROKEN RAIL PROTECTION

20210139059

16/476668

June 02, 2017

Aspects of the disclosed embodiments generally relate to railway track circuits, in particular track circuits with continued distance monitoring and broken rail protection.

1. A track circuit for a railroad track block, said track circuit comprising: a first occupied track device connected to rails of the railroad track block at a first portion of the block; and a second occupied track device connected to the rails of the railroad track block at a second portion of the block, said first and second occupied track devices being configured to: detect a presence of a train on the rails of the block using a DC function, and once the presence of the train is detected, determine an amount of unoccupied track behind the train using an AC function.

2. The track circuit of claim 1, wherein the DC function comprises transmitting DC coded signals along the rails of the block and detecting the presence of the train within the block based on the DC coded return signals along the rails.

3. The track circuit of claim 1, wherein the AC function comprises transmitting low frequency AC signals along the rails of the block and determining the amount of unoccupied track behind the train based on impedance characteristics of AC return signals along the rails.

4. The track circuit of claim 3, wherein the AC function further comprises determining an amount of unoccupied track ahead of the train based on an impedance characteristic of AC return signals along the rails.

5. The track circuit of claim 1, wherein said first and second occupied track devices are configured to determine if one or more of the rails in the block are broken while the train is within the block.

6. The track circuit of claim 1, wherein each occupied track device comprises: a transmitter connected to the rails of the block, the transmitter being controllable to transmit DC coded signals along the rails of the block during the DC function and to transmit low frequency AC signals along the rails of the block during the AC function; and a receiver connected to the rails of the block, the receiver being controllable to receive DC coded signals along the rails of the block during the DC function and to receive low frequency AC signals along the rails of the block during the AC function.

7. The track circuit of claim 6, wherein each occupied track device further comprises a control unit connected to the respective transmitter and receiver, said control unit being adapted to detect the presence of the train within the block based on the DC coded return signals along the rails and to determine the amount of unoccupied track behind the train based on impedance characteristics of AC return signals along the rails.

8. The track circuit of claim 7, wherein each control unit is further adapted determine an amount of unoccupied track ahead of the train based on an impedance characteristic of AC return signals along the rails.

9. The track circuit of claim 1, wherein said first occupied track device is calibrated in accordance with an impedance of the second occupied track device and said second occupied track device is calibrated in accordance with an impedance of the first occupied track device.

10. The track circuit of claim 9, wherein said first and second occupied track devices are configured to determine if one or more of the rails in the block are broken while the train is within the block based on one or more impedance readings along the rails of the track.

11. A method of monitoring a railroad track block, said track method comprising: performing a DC function to detect a presence of a train on rails of the block; and once the presence of the train is detected, performing an AC function to determine an amount of unoccupied track behind the train.

12. The method of claim 11, wherein performing the DC function comprises: transmitting DC coded signals along the rails of the block; and detecting the presence of the train within the block based on the DC coded return signals along the rails.

13. The method of claim 11, wherein performing the AC function comprises: transmitting low frequency AC signals along the rails of the block; and determining the amount of unoccupied track behind the train based on impedance characteristics of AC return signals along the rails.

14. The method of claim 13, wherein performing the AC function further comprises determining an amount of unoccupied track ahead of the train based on an impedance characteristic of AC return signals along the rails.

15. The method of claim 11, further comprising the act of determining if one or more of the rails in the block are broken while the train is within the block.

16. The method of claim 11, further comprising: providing a first occupied track device at a first end of the block; providing a second occupied track device at a second end of the block; calibrating the first occupied track device in accordance with an impedance of the second occupied track device; and calibrating the second occupied track device in accordance with an impedance of the first occupied track device.

17. The method of claim 16, further comprising determining if one or more of the rails in the block are broken while the train is within the block based on one or more impedance readings along the rails of the track.

18. An occupied track device adapted to be connected to rails of a railroad track block, said occupied track device comprising: a transmitter adapted to be connected to the rails of the block, the transmitter being controllable to transmit DC coded signals along the rails of the block during a DC function and to transmit low frequency AC signals along the rails of the block during an AC function; a receiver adapted to be connected to the rails of the block, the receiver being controllable to receive DC coded signals along the rails of the block during the DC function and to receive low frequency AC signals along the rails of the block during the AC function; and a control unit connected to the transmitter and receiver, said control unit being adapted to detect the presence of the train within the block based on the DC coded return signals along the rails and to determine the amount of unoccupied track behind the train based on impedance characteristics of AC return signals along the rails.

19. The occupied track device of claim 18, wherein the AC function further comprises determining an amount of unoccupied track ahead of the train based on an impedance characteristic of AC return signals along the rails.

20. The occupied track device of claim 18, wherein said occupied track device is configured to determine if one or more of the rails in the block are broken while the train is within the block.

61; 61

edspap.20210139059