Track circuit mechanical joint integrity checker

Abstract

An electrically insulating mechanical joint checker for mechanical joints connecting rails of following track segments of a railway line, each track segment forming part of a track circuit. The track segment includes electric signal transmitting units and receiving units for transmitting and receiving train presence detection signals within the track segment and/or relating communication signals between the train and the track segment. The train presence detection signals and communication signals include a further joint detection signal, generated and transmitted by the transmitting units and received by the receiving units belonging to the same track segment, the joint detection signal relating to the track segment being different at least in respect to the one relating to the adjacent track segments. A method to detect a failure or breakage of a mechanical joint inside a track segment is also disclosed.

Claims

1. An electrically insulating mechanical joint checker for mechanical joints connecting rails of subsequent track segments of a railway line, each track segment forming part of a track circuit, comprising: a signal transmitting unit and a receiving unit operatively coupled to each track segment for transmitting and respectively receiving train presence detection signals within said track segment and/or transmitting and respectively receiving communication signals between a train and the track segment, wherein said signal transmitting unit and receiving unit are configured to respectively transmit and receive an additional joint insulation integrity signal associated to each track segment to detect failure of insulation of said mechanical joints, wherein said signal transmitting unit and receiving unit are configured to respectively transmit and receive said joint insulation integrity signal related to the said track segment, which is different at least in respect to a joint insulation integrity signal relating to an adjacent track segment in parameters uniquely identifying the joint insulation integrity signal of each track segment, wherein said signal transmitting unit comprises a signal generation unit generating and transmitting said joint insulation integrity signal, and said signal receiving unit comprises an analyzing unit comparing a received joint insulation integrity signal with the joint insulation integrity signal that identifies the track segment, wherein said transmitting unit comprises a timing system that activates the signal generation unit according to a predetermined timing rule, wherein said signal transmitting unit and said receiving unit provide said train presence detection signals and said communication signals as a wave having an amplitude maximum value and an amplitude minimum value, and wherein said generation unit is activated by said timing system during a time interval of amplitude minimum value.

2. The electrically insulating mechanical joint checker according to claim 1, wherein said signal transmitting and receiving units are configured to transmit and receive said joint insulation integrity signal from frequency-shift keying modulation, in which a bit with value 1 presents a carrier frequency of 525 Hz while a bit with value 0 presents a carrier frequency of 475 Hz.

3. The electrically insulating mechanical joint checker according to claim 1, further comprising a system that sets the track circuit in a safety condition.

4. The electrically insulating mechanical joint checker according to claim 1, wherein said signal transmitting and receiving units are configured to transmit and receive said joint insulation integrity signal as a digital signal comprising a bit coded message.

5. The electrically insulating mechanical joint checker according to claim 4, wherein said bit coded message is composed by 8 bit.

6. The electrically insulating mechanical joint checker according to claim 1, wherein said signal transmitting and receiving units are configured to transmit and receive said joint insulation integrity signal with a carrier frequency of 500 Hz, and wherein the said signal transmitting units are configured to generate carrier waves.

7. A method of detecting a failure or breakage of a mechanical joint connecting rails of subsequent track segments of a railway line, each track segment forming part of a track circuit, wherein each track segment is operatively coupled to a signal transmitting unit and a receiving unit adapted to transmit and respectively receive train presence detection signals within said track segment and/or communications signals between a train and said track segment, the method comprising: (a) causing the transmitting unit to generate an additional joint insulation integrity signal, which is associated to each track segment, said joint insulation integrity signal associated with said track segment being different from the joint insulation integrity signal associated with an adjacent track segments in parameters uniquely identifying the joint insulation integrity signal of each track segment; (b) transmitting said joint insulation integrity signal with the said transmitting unit; (c) receiving said joint insulation integrity signal at said receiving unit; (d) comparing the received joint insulation integrity signal with the joint insulation integrity signal that identifies the track segment with said receiving unit, said transmitting unit and said receiving unit belonging to a same track segment; and (e) setting said track segment in an occupied status, further comprising the step of causing said signal transmitting and said receiving unit to transmit and receive said train presence detection signals and said communication signals as a wave having an amplitude maximum value and an amplitude minimum value, wherein the step of transmitting said joint insulation integrity signal occurs only during a time interval of amplitude minimum value.

8. The method according to claim 7, wherein transmitting said joint insulation integrity signal comprises transmitting said joint insulation integrity signal as a digital signal comprising a bit coded message.

9. The method according to claim 8, wherein the bit coded message is composed by 8 bit.

10. The method according to claim 8, wherein step (b) comprises the steps of: (b1) transmitting said joint insulation integrity signal comprising said bit coded message, and (b2) transmitting of said joint insulation integrity signal comprising a logical complement of said bit coded message.

11. The method according to claim 7, wherein transmitting said joint insulation integrity signal comprises transmitting said joint insulation integrity signal with a carrier frequency of 500 Hz.

12. The method according to claim 11, wherein step (a) is obtained by a Frequency-shift keying modulation, in which a bit with value 1 has a carrier frequency of 525 Hz and a bit with value 0 has a carrier frequency of 475 Hz.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics and advantages of the invention will be more apparent from the following description of a few embodiments shown in the accompanying drawings, in which:

(2) FIG. 1 shows one of the possible embodiments of a track circuit according to the prior art;

(3) FIG. 2 shows a possible scenario in the case of a failure of a mechanical joint;

(4) FIG. 3 shows one of the possible embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(5) FIG. 1 shows a electrically insulating mechanical joint for track circuits according to the prior art for railway systems or the like, comprising a track segment 11 of predetermined length, which segment comprises at least two rails 111 and 112,

(6) The track segment 11 is electrically insulated from adjacent segments 12, comprising at least two rails 121 and 122, by mechanical joints 21 and 22.

(7) The joints 21 and 22 connect together each rail 111, 112 of the track segment 11 with a corresponding rail 121, 122 belonging to adjacent track segments 12 at the ends of each track segment.

(8) Each track segment 11 and 12 presents electric signal transmitting units 3 and receiving units 4 for transmitting and receiving train presence detection signals within the track segment 11 and/or communication signals between a train 7 and the track segment.

(9) The track circuit illustrated in FIG. 1 and belonging to the prior art presents two further means, respectively a joint integrity transmitter 41 and a joint integrity receiver 42 to detect the integrity of the mechanical joints 21 and 22.

(10) The integrity joint transmitter 41 inject a dedicated frequency versus the couple of mechanical joints 21 and 22, received by the joint integrity receiver 42. If the mechanical joints 21 and 22 break the receiver 42 will detect it.

(11) As described above the track circuits belonging to the prior art requires additional means, such as, in this case, joint integrity transmitter 41 and joint integrity receiver 42, incurring in further costs and requiring to modify the configuration of the track circuit.

(12) The possible scenario in the case of a failure of a mechanical joint is illustrated in FIG. 2.

(13) A train 7 with its axles enters in the track circuit 12 and the receiver 4 connected to that track circuit, senses the shunt resistance of the train 7 and correctly put the track segment in occupied status.

(14) In the same moment a breaking of the mechanical joint 21 occurs.

(15) The train 7 receives the codes that is propagating from track segment 11 to track segment 12 due to the loss of insulation of the mechanical joint 21.

(16) FIG. 3 shows how the mechanical joint checker for track segments according to the present invention detect the failure of a mechanical joint.

(17) The signals circulating in the track segments 11 and 12 comprise a further joint insulation integrity signal A, B associated to each track segment 11, 12 in order to detect the failure of the insulation of the mechanical joints 21, 22.

(18) The joint insulation integrity signal A relating to track segment 11 is different, concerning to characteristic parameters uniquely identifying the joint insulation integrity signal of each track segment, to the integrity signal B relating to the track segment 12.

(19) The joint insulation integrity signal A is generated and transmitted by the transmitting units 3 belonging to the track segment 11 and it is received by the receiving units 4 belonging to the track segment 11.

(20) The joint insulation integrity signal B is generated and transmitted by the transmitting units 3 belonging to the track segment 12 and it is received by the receiving units 4 belonging to the track segment 12.

(21) The transmitting units 3 comprise a signal generation unit 31 that generates the signals circulating in the track segment 11.

(22) Because signals A and B are differentiated, if the mechanical joints 21 or 22 break both the receivers of track segment 11 and 12 detect the breaking of the mechanical joints 2 or 22.

(23) In particular the receiving units 4 belonging to the track segment 11 knows the joint insulation integrity signal A transmitted by the corresponding transmitting units 3, and therefore if it receives a signal different from A or an attenuated one, it means that a loss of insulation occurs due to the failure of one of the mechanical joints 21 and 22.

(24) Means for setting the track segment in a safety condition are provided.

(25) As usual when such condition appears, an alarm signal can be sent to remote operating unit and automatically the track segments 11 and 12 are put in occupied status.

(26) The receiving units 4 comprise an analyzing unit 41 which compares the received joint insulation integrity signal with the one that identifies the track segment 11.

(27) The analyzing unit 41 in particular compares the characteristic parameters of the received joint insulation integrity signal with predetermined values.

(28) The characteristic parameters analyzed are the amplitude, carrier frequency, modulation frequency and bit message content of the received signal.

(29) The predetermined values can be set on the base of a joint insulation integrity signal A not corrupted or attenuated.

(30) Also the discriminant to evaluate the difference between one signal and the following one can be set.

(31) As described above, in the case the joint insulation integrity signal is a bit coded message, a message can be identified as different in respect of a following message if the second one presents a Hamming distance equal to 3 in respect of the first message.

(32) The same consideration is valid relating to track segment 12.

(33) Preferably the joint insulation integrity signals

(34) A and B are digital signals comprising a bit coded messages.

(35) According to a possible embodiment of the present invention, the joint insulation integrity signal presents a carrier frequency of 500 Hz, the said signal generation unit 31 including means to generate carrier waves.

(36) An improvement of the present invention provides that the joint insulation integrity signals A and B are obtained by a Frequency-shift keying modulation, in which the bit with value 1 presents a carrier frequency of 525 Hz while the bit with value 0 presents a carrier frequency of 475 Hz.

(37) Advantageously the joint insulation integrity signals A and B are bit coded messages composed by 8 bit.

(38) Furthermore, with 8 bit messages it is possible to create different type of messages according to the configuration of the track segment.

(39) For example if the track segments are disposed like the ones of FIG. 3, it will be sufficient to provide a sequence like A-B-A-B.

(40) If there is the need of another couple of mechanical joints, due to a ramification of the track segment 11, it will be sufficient to use another bit message C different from A and B.

(41) With a double ramification of the track segment 11 another message D will be required.

(42) As clearly appears from the figures the mechanical joint checker of the present invention brings to the realization of a method to detect a failure or breakage of a mechanical joint 21 or 22 inside a track segment.

(43) This method provides the step of: a) generation of a further joint insulation integrity signal A, B by the transmitting units 3; b) transmission of the joint insulation integrity signal A,B by the transmitting units 3; c) reception of the joint insulation integrity signal A, B by the receiving units 4; d) comparison of the received joint insulation integrity signal with the one that identifies the track segment; e) set of the said track segment 11 in a occupied status.

(44) As previously described, the message A is transmitted by the transmitting units 3 belonging to the track segment 11 and it is received by the receiving units belonging to the track segment 11.

(45) According to a preferred embodiment the train presence detection signals and the communication signals are constituted by a wave, which wave presents an amplitude maximum value and an amplitude minimum value, the transmission of the joint insulation integrity signal occurring only during time interval of amplitude minimum value.

(46) In this case according to a preferred embodiment the transmitting units 3 comprise timing means 32, which timing means 32 activate the signal generation unit 31 according to predetermined timing rules.

(47) One of the possible timing rules is the one above described, e.g. activating the generation unit during the time interval of amplitude minimum value.

(48) The timing means allow to control the timing of the transmission of the joint insulation integrity signal A, B.

(49) Furthermore the transmission of the joint insulation integrity signal A,B comprises the step of: b1) transmission of the joint insulation integrity signal A, B constituted by a bit message; b2) transmission of the joint insulation integrity signal constituted by the logical complement of the said bit message.

(50) In this case it is possible to provide logic control units that control and set the generation of the joint insulation integrity signal.