Rail break and train detection system and rail break and train detection method

Abstract

To achieve both rail breakage detection and train detection while suppressing cost.SOLUTION: A rail break and train detection system 10 includes a transmission unit 14 that transmits AC signals of a first frequency f1 and a second frequency f2 to a first rail pair 50, a reception unit 18 that receives an AC signal from a second rail pair 54, a first series resonant circuit unit 22 having the first frequency f1 as a resonant frequency, a second series resonant circuit unit 26 having the second frequency f2 as a resonant frequency, and a determination control unit 30 that compares a reception level of a received AC signal of the reception unit 18 with a preset reception level threshold value to determine the presence or absence of a rail break or train presence, and separates the rail break from the train presence based on a degree of change in the reception level of the received AC signal. Accordingly, it is possible to realize both rail break detection and train detection while suppressing the cost with an inexpensive configuration following the track circuit system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system and method for detecting rail breaks and trains on railway lines. [Background technology]

[0002] Conventionally, railway lines using track circuits that energize rails have not only detected the presence of trains but also rail breakages. However, in recent years, technology for detecting trains without using track circuits has been established, and in such cases, rail breakage detection must be performed by a different method. Therefore, the present inventors have previously proposed an inexpensive rail breakage detection device that follows the track circuit method, taking into account use in environments where train detection function is not essential (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-152172 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to solve this problem, the inventors of the present invention have been studying ways to additionally detect trains while maintaining a low-cost configuration of the rail breakage detection device. As a result, they have focused on the ability to distinguish between rail breakage and the presence of a train on the track, and have arrived at the present invention. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to achieve both rail breakage detection and train detection while suppressing costs. [Means for solving the problem]

[0005] (Aspects of the invention) The following embodiments of the present invention are examples of the configuration of the present invention, and are described in terms to facilitate understanding of the various configurations of the present invention. Each term does not limit the technical scope of the present invention, and while taking into consideration the best mode for carrying out the invention, some of the components of each term may be replaced or deleted, or other components may be added, and these may also be included in the technical scope of the present invention.

[0006] (1) A system for detecting rail breaks and trains on a railway line including first and second pairs of rails laid in parallel, comprising: a transmitter that transmits AC signals of a first frequency and AC signals of a second frequency to the first pair of rails; a receiver that receives AC signals from the second pair of rails near the transmitter; a first series resonant circuit that connects the first pair of rails and the second pair of rails at a position away from the transmitter and the receiver on one side in the direction of rail extension and has the first frequency as a resonant frequency; and a second series resonant circuit that connects the first pair of rails and the second pair of rails at a position away from the transmitter and the receiver on the other side in the direction of rail extension and has the second frequency as a resonant frequency. and a judgment control unit that makes a judgment based on a received AC signal received by the receiving unit, using a first region between the connection point of the first series resonant circuit unit and the connection point of the transmitter and receiver of the first rail pair and the second rail pair as judgment regions, and a second region between the connection point of the second series resonant circuit unit and the connection point of the transmitter and receiver, wherein the judgment control unit compares the reception level of the received AC signal with a preset reception level threshold to determine the presence or absence of a rail break or a train presence, and distinguishes between a rail break and a train presence on the track based on the degree of change in the reception level of the received AC signal.

[0007] The rail break and train detection system described in this section is for detecting both rail breaks and the presence of trains on a railway line including a first pair of rails and a second pair of rails, and includes a transmitter, a receiver, a first series resonant circuit, a second series resonant circuit, and a judgment control unit. The transmitter transmits AC signals to the first pair of rails and is capable of transmitting both AC signals of a first frequency and AC signals of a second frequency. The receiver receives AC signals from the second pair of rails near the transmitter, more specifically near the point where the transmitter transmits the AC signals to the first pair of rails. In other words, the transmitter and receiver are installed so that the point where the transmitter transmits the AC signals to the first pair of rails and the point where the receiver receives the AC signals from the second pair of rails are close to each other.

[0008] The first series resonant circuit unit has a resonant circuit with a first frequency as its resonant frequency so as to pass only AC signals of the first frequency transmitted from the transmitter unit. The first series resonant circuit unit is installed at a position away from the transmitter unit and the receiver unit on one side in the rail extension direction, connecting the first rail pair and the second rail pair. In contrast, the second series resonant circuit unit has a resonant circuit with a second frequency as its resonant frequency so as to pass only AC signals of the second frequency transmitted from the transmitter unit. The second series resonant circuit unit is installed at a position away from the transmitter unit and the receiver unit on the other side in the rail extension direction, connecting the first rail pair and the second rail pair. That is, the first pair of rails and the second pair of rails are connected by a first series resonant circuit unit at a position separated on one side of the rail extension direction, separated by the point of transmission to the first pair of rails by the transmitter and the point of reception from the second pair of rails by the receiver, and are connected by a second series resonant circuit unit at a position separated on the other side of the rail extension direction.

[0009] The determination control unit performs a determination using a first region and a second region as determination regions. Here, the first region is the region between the connection point of the first series resonant circuit unit of the first rail pair and the second rail pair and the connection point of the transmitter and receiver. The second region is the region between the connection point of the second series resonant circuit unit of the first rail pair and the second rail pair and the connection point of the transmitter and receiver. Furthermore, the determination control unit performs a determination based on a received AC signal received by the receiver from the second rail pair. That is, when an AC signal of a first frequency is transmitted from the transmitter, it is received by the receiver via the first series resonant circuit unit, and therefore the determination is performed on the AC signal passing through the first region. Therefore, when the AC signal received by the receiver is an AC signal of the first frequency, the determination control unit performs a determination on the first region based on the received AC signal. On the other hand, when an AC signal of the second frequency is transmitted from the transmitter, it is received by the receiver via the second series resonant circuit, and therefore the determination is made on the AC signal passing through the second region. Therefore, when the AC signal received by the receiver is an AC signal of the second frequency, the determination control unit makes a determination on the second region based on the received AC signal.

[0010] More specifically, the determination control unit compares the reception level of the received AC signal of the first frequency or the second frequency with a preset threshold value for the reception level to determine whether a rail break or a train is present. Furthermore, if the determination control unit determines that either a rail break or a train is present, it distinguishes between the rail break and the presence of a train based on the degree of change in the reception level of the received AC signal. That is, the inventors have discovered a difference between the degree of change in the reception level of the received AC signal when a rail break occurs and the degree of change in the reception level of the received AC signal when a train is present, and this difference is used to distinguish between the rail break and the presence of a train. Specifically, when a rail break occurs, the reception level of the received AC signal tends to change sharply, while when a train is present, the reception level of the received AC signal tends to change gradually. This allows both rail break detection and train detection to be achieved while keeping costs down with an inexpensive configuration based on a track circuit system.

[0011] (2) In the above paragraph (1), the threshold value is set based on the reception level of the received AC signal when a rail break has occurred in the judgment area, the reception level of the received AC signal when a train is present in the judgment area, and the reception level of the received AC signal when neither a rail break nor a train is present in the judgment area, which are obtained from simulations and / or experiments. In the rail break and train detection system described in this section, the threshold value of the reception level preset in the determination control unit is set taking into account values ​​obtained from simulations and / or experiments. Specifically, the reception levels of the AC signals received by the receiving unit are determined from simulations and / or experiments for each of a state in which a rail break has occurred in the determination area, a state in which a train is present in the determination area, and a state in which neither a rail break nor a train is present in the determination area. Then, based on the reception levels of these received AC signals, a threshold value of the reception level is set for the determination control unit to determine whether a rail break or a train is present. This allows the presence or absence of a rail break or a train to be determined with high accuracy.

[0012] (3) In the above paragraph (1), the judgment control unit uses a predetermined period and a predetermined number of times that are set in advance, and calculates the level difference between consecutive unit data using the reception level of the received AC signal acquired consecutively for the predetermined number of times at the predetermined period as unit data, and uses the level difference as the degree of change in the reception level. In the rail break and train detection system described in this section, the determination control unit determines and uses unit data of the reception level when distinguishing between a rail break and a train presence on the track. That is, the reception AC signal is acquired from the receiving unit a predetermined number of times in a predetermined cycle, and the reception level of the reception AC signal for those predetermined cycles is used as unit data. The predetermined cycle and the predetermined number of times are set taking into consideration ease of calculation, etc. The determination control unit then uses the determined unit data to calculate the level difference between consecutive unit data, and uses this level difference as the degree of change in the reception level of the reception AC signal for distinguishing between a rail break and a train presence on the track. This enables efficient and accurate distinction between a rail break and a train presence on the track.

[0013] (4) In the above-mentioned (3), the judgment control unit distinguishes between a rail break and a train being present on the track by using a level difference threshold value set based on the level difference when a rail break has occurred in the judgment area and the level difference when a train is present on the track in the judgment area, which are obtained from simulations and / or experiments. In the rail break and train detection system described in this section, when the judgment control unit distinguishes between a rail break and a train presence on the track, it uses a threshold value for the level difference between consecutive unit data as mentioned in section (3) above. That is, the level difference between consecutive unit data is determined through simulation and / or experiment for each of the states where a rail break has occurred in the judgment area and the state where a train is present in the judgment area. Then, based on these level differences, a level difference threshold value is set for the judgment control unit to distinguish between a rail break and a train presence on the track. This enables the judgment control unit to distinguish between a rail break and a train presence on the track with greater accuracy.

[0014] (5) In the above paragraph (1), the judgment control unit uses both the judgment result in the first area and the judgment result in the second area to determine whether a rail break has occurred while the train is running. This is a rail break and train detection system. In the rail break and train detection system described in this section, the determination control unit determines whether a rail break has occurred while a train is running. It is expected that when a rail break occurs while a train is running, the reception level of the AC signal received by the receiving unit will exhibit more characteristic behavior compared to when either a train is present on the track or a rail break occurs. Therefore, the determination control unit normally uses the determination results in the first region and the determination results in the second region separately, but determines whether a rail break has occurred while the train is running by combining these two determination results. The determination results here may include the determination results of the presence or absence of a rail break or a train on the track in the first region and the second region, the distinction between them, the reception level of the AC signal, etc. This allows for a smooth determination even when a rail break occurs while a train is running.

[0015] (6) In the above paragraph (5), when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, the judgment control unit sequentially judges that a train is present in the first area and the second area, and then determines that a train has changed from being present in the second area to not being present in the second area, but continues to judge that a train is present in the first area, and determines that a rail break has occurred in the first area.

[0016] The rail break and train detection system described in this section determines that a rail break has occurred in the first area when a train is traveling on a first pair of rails or a second pair of rails from one side to the other in the direction of rail extension, in other words, from the first area to the second area, as follows: The determination control unit sequentially determines that a train is present in the first area and then in the second area, and then determines that a train has changed from being present in the second area to not being present in the second area, but continues to determine that a train is present in the first area, and then determines that a rail break has occurred in the first area. This pattern of combination of determination results was discovered by the inventors through simulations, etc. This allows for a smooth determination that a rail break has occurred in the first area while a train is traveling from the first area to the second area.

[0017] (7) In the above paragraph (5), when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, the judgment control unit judges that a train is present in both the first area and the second area, and then judges that a train has changed to a non-presence state in the first area, and when the degree of change in the reception level of the received AC signal at that time is equal to or greater than a preset threshold value for the degree of change and the judgment that a train is present in the second area continues, the judgment control unit judges that a rail break has occurred in the second area.

[0018] The rail break and train detection system described in this section determines that a rail break has occurred in the second area when a train is traveling on a first pair of rails or a second pair of rails from one side to the other in the direction of rail extension, in other words, from the first area to the second area, as follows: The determination control unit determines that a train is present in both the first area and the second area, and then determines that the state of the first area has changed to that of a train not present on the tracks, and determines that a rail break has occurred in the second area if the degree of change in the reception level of the received AC signal at that time is equal to or greater than a preset threshold value for the degree of change, and the system continues to determine that a train is present on the tracks in the second area. The inventors discovered these patterns of combinations of determination results and the threshold value for the degree of change through simulations, etc. This allows for a smooth determination that a rail break has occurred in the second area while a train is traveling from the first area to the second area.

[0019] (8) A method for detecting rail breaks and trains on a railway line including first and second pairs of rails laid in parallel, comprising: installing a transmitter that transmits an AC signal of a first frequency and an AC signal of a second frequency to the first pair of rails; and installing a receiver that receives an AC signal from the second pair of rails near the transmitter; connecting the first pair of rails and the second pair of rails by a first series resonant circuit unit having a resonant frequency of the first frequency at a position away from the transmitter and the receiver on one side in the direction of extension of the rails; and connecting the first pair of rails and the second pair of rails by a first series resonant circuit unit having a resonant frequency of the first frequency at a position away from the transmitter and the receiver on the other side in the direction of extension of the rails. A rail break and train detection method in which the first rail pair and the second rail pair are connected by a series resonant circuit unit, and a first region between the connection point of the first rail pair and the connection point of the first series resonant circuit unit and the connection point of the transmitter and the receiver, and a second region between the connection point of the second series resonant circuit unit and the connection point of the transmitter and the receiver are used as judgment regions, and the reception level of the received AC signal received by the receiver is compared with a preset reception level threshold to determine whether there is a rail break or a train on the track, and distinguish between a rail break and a train on the track based on the degree of change in the reception level of the received AC signal.

[0020] (9) In the rail break and train detection method described in (8) above, the threshold value is set based on the reception level of the received AC signal when a rail break has occurred in the judgment area, the reception level of the received AC signal when a train is present in the judgment area, and the reception level of the received AC signal when neither a rail break nor a train is present in the judgment area, which are obtained from simulations and / or experiments. (10) In the above (8), a rail break and train detection method is provided, in which a predetermined period and a predetermined number of times are used to obtain the reception level of the received AC signal continuously at the predetermined period for the predetermined number of times, and the reception level is used as unit data, and the level difference between successive unit data is calculated and the level difference is used as the degree of change in the reception level.

[0021] (11) A rail break and train detection method as described in (10) above, which distinguishes between a rail break and a train being present on the track by using a level difference threshold value set based on the level difference when a rail break has occurred in the determination area and the level difference when a train is present in the determination area, both obtained through simulation and / or experiment. (12) In the above (8), a rail break and train detection method is provided, which uses both the judgment result in the first area and the judgment result in the second area to determine whether a rail break has occurred while a train is running. (13) In the above paragraph (12), when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, the method sequentially determines that a train is present in the first area and the second area, and then determines that a train is present in the first area even though it determines that the state of the train in the second area has changed from being present to not being present, and then determines that a rail break has occurred in the first area.

[0022] (14) A rail break and train detection method as described in paragraph (12) above, which determines that a train is present in both the first area and the second area when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, and then determines that a train has changed to a non-presence state in the first area, and determines that a rail break has occurred in the second area if the degree of change in the reception level of the received AC signal at that time is equal to or greater than a preset threshold value for the degree of change and the second area continues to determine that a train is present on the rail. The rail break and train detection methods described in paragraphs (8) to (14) are each implemented using the rail break and train detection systems described in paragraphs (1) to (7) above, and thus have the same effects as those of the rail break and train detection systems described in paragraphs (1) to (7) above. [Effects of the Invention]

[0023] Because the present invention has the above-described configuration, it is possible to achieve both rail breakage detection and train detection while suppressing costs. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a rail breakage and train detection system according to an embodiment of the present invention; [Figure 2] The detection process is shown in Figure 1 using the rail break and train detection system. (a) is an image of detecting a train on the track, and (b) is an image of detecting a rail break. [Figure 3] The graphs show the change in reception level of the AC signal received by the receiving unit when the train is running, where (a) is a graph showing an example of the change in reception level when an AC signal of a first frequency is transmitted, and (b) is a graph showing an example of the change in reception level when an AC signal of a second frequency is transmitted. [Figure 4] 10 shows the change in the reception level of the AC signal received by the receiving unit when the rail breaks, where (a) is a graph showing an example of the change in reception level when an AC signal of a first frequency is transmitted, and (b) is a graph showing an example of the change in reception level when an AC signal of a second frequency is transmitted. [Figure 5] The graphs show the level difference between two consecutive unit data values ​​of the reception level, where (a) is a graph showing an example of the level difference when a train is running, and (b) is a graph showing an example of the level difference when a rail is broken. [Figure 6] 10A and 10B are diagrams for explaining a method for determining if a rail break occurs in a first area while a train is running, in which (a) is a graph showing an example of changes in reception level when AC signals of a first frequency and a second frequency are transmitted, and (b) is a table showing determination patterns. [Figure 7] 10A and 10B are diagrams for explaining a method of determining if a rail break occurs in a second area while a train is running, in which (a) is a graph showing an example of changes in reception level when AC signals of a first frequency and a second frequency are transmitted, and (b) is a table showing determination patterns. [Figure 8] FIG. 2 is a state transition diagram showing an example of state changes and their conditions in the rail break and train detection system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, detailed descriptions of parts that are the same as or corresponding to those in the prior art will be omitted, and the same reference numerals will be used throughout the drawings to indicate the same or corresponding parts. 1 is a schematic diagram showing an example of the configuration of a rail break and train detection system 10 according to an embodiment of the present invention, together with a railway line to which the system is applied. The railway line to which the system is applied includes a first pair of rails 50 (rails 51, 52) and a second pair of rails 54 (rails 55, 56) laid in parallel, with the first pair of rails 50 being an up line and the second pair of rails 54 being a down line, for example.

[0026] As shown in the figure, a rail break and train detection system 10 according to an embodiment of the present invention includes a transmitter 14, a receiver 18, a first series resonant circuit unit 22, a second series resonant circuit unit 26, and a determination controller 30. The transmitter 14 is connected to a first pair of rails 50 so as to transmit an AC signal to the first pair of rails 50. That is, one output terminal of the transmitter 14 is connected to one rail 51 of the first pair of rails 50, and the other output terminal of the transmitter 14 is connected to the other rail 52 of the first pair of rails 50; hereinafter, this connection point is also referred to as a "transmission point 16." The transmitter 14 is configured to transmit both an AC signal at a first frequency f1 and an AC signal at a second frequency f2. For example, the transmitter 14 may be controlled to transmit these AC signals alternately or to transmit these AC signals in a superimposed manner. The transmitter 14 of this embodiment is configured to switch between outputting an AC signal of the first frequency f1 and an AC signal of the second frequency f2 under the control of the determination control unit 30. Note that the transmitter 14 may be capable of transmitting AC signals of frequencies other than the first frequency f1 and the second frequency f2, in addition to these AC signals, and may be similar to a transmitter for a track circuit that has been conventionally used.

[0027] The receiver 18 is connected to the second rail pair 54 so as to receive AC signals from the second rail pair 54. That is, one input terminal of the receiver 18 is connected to one rail 55 of the second rail pair 54, and the other input terminal of the receiver 18 is connected to the other rail 56 of the second rail pair 54; hereinafter, this connection point is also referred to as a "reception point 20." The receiver 18 is installed near the transmitter 14 so that the reception point 20 from the second rail pair 54 is close to the transmission point 16 of the transmitter 14 to the first rail pair 50. The receiver 18 may be any device capable of receiving AC signals transmitted from the transmitter 14, and may be, for example, similar to a conventional track circuit receiver.

[0028] The first series resonant circuit unit 22 is installed at a position away from the transmitting point 16 and the receiving point 20 on one side in the rail extension direction (the left side in FIG. 1 ) so as to connect the first rail pair 50 and the second rail pair 54. That is, the first series resonant circuit unit 22 connects one rail 51 of the first rail pair 50 to one rail 55 of the second rail pair 54, and also connects the other rail 52 of the first rail pair 50 to the other rail 56 of the second rail pair 54. This first series resonant circuit unit 22 has a first frequency f1 as its resonant frequency, and is configured to pass only AC signals of the first frequency f1 and not pass AC signals or DC signals of other frequencies.

[0029] Therefore, when an AC signal of a first frequency f1 is transmitted from the transmitter 14, a current path is formed from one rail 51 of the first rail pair 50 via the first series resonant circuit unit 22, one rail 55 of the second rail pair 54 to the receiver 18, and then from there via the other rail 56 of the second rail pair 54, the first series resonant circuit unit 22, and the other rail 52 of the first rail pair 50, returning to the transmitter 14. In FIG. 1, an image of such current flow is shown by a simplified arrow with the symbol f1. Note that the first series resonant circuit unit 22 is not limited to the coil and capacitor circuit shown in FIG. 1, and may have any circuit configuration as long as it has the above-mentioned function.

[0030] The second series resonant circuit unit 26 is installed at a position away from the transmitting point 16 and the receiving point 20 on the other side in the rail extension direction (the right side in FIG. 1 ) so as to connect the first rail pair 50 and the second rail pair 54. That is, the second series resonant circuit unit 26 connects one rail 51 of the first rail pair 50 to one rail 55 of the second rail pair 54, and also connects the other rail 52 of the first rail pair 50 to the other rail 56 of the second rail pair 54. The second series resonant circuit unit 26 has a second frequency f2 as its resonant frequency, and is configured to pass only AC signals of the second frequency f2 and not pass AC signals or DC signals of other frequencies.

[0031] Therefore, when an AC signal of the second frequency f2 is transmitted from the transmitter 14, a current path is formed from one rail 51 of the first rail pair 50 via the second series resonant circuit unit 26, one rail 55 of the second rail pair 54 to the receiver 18, and then from there via the other rail 56 of the second rail pair 54, the second series resonant circuit unit 26, and the other rail 52 of the first rail pair 50, returning to the transmitter 14. In FIG. 1, an image of such current flow is shown by a simplified arrow with the symbol f2. Note that the second series resonant circuit unit 26 is not limited to the coil and capacitor circuit shown in FIG. 1, and may have any circuit configuration as long as it has the above-mentioned function.

[0032] 1, the distance in the direction of rail extension between the nearby transmitting point 16 and receiving point 20 is preferably, for example, 0 m to several meters. In this case, the transmitting unit 14 and the receiving unit 18 may be integrated transmitters and receivers. In contrast, the distance in the direction of rail extension between the transmitting point 16 and the receiving point 20 and the first series resonant circuit unit 22 is set taking into account the transmittable distance of the transmitting unit 14 and the receivetable distance of the receiving unit 18, and is, for example, 1 km to 2 km. The distance between the transmitting point 16 and the receiving point 20 and the second series resonant circuit unit 26 is also approximately the same as the distance between the transmitting point 16 and the receiving point 20 and the first series resonant circuit unit 22. In such an arrangement, for ease of explanation, the region of the first rail pair 50 and the second rail pair 54 between the transmitting point 16 and the receiving point 20 and the first series resonant circuit unit 22 is referred to as the first region LT, and the region of the first rail pair 50 and the second rail pair 54 between the transmitting point 16 and the receiving point 20 and the second series resonant circuit unit 26 is referred to as the second region RT.

[0033] The determination control unit 30 uses the first region LT and the second region RT as determination regions and makes various determinations related to the detection of rail breaks and train presence based on the received AC signals received by the receiver 18. The determination region determined by the determination control unit 30 becomes the track monitored by the rail break and train detection system 10. The determination content and method by the determination control unit 30 will be described later. The determination control unit 30 also performs various controls required for the rail break and train detection system 10, such as switching the frequency of the AC signal transmitted from the transmitter 14. Such a determination control unit 30 may be configured by combining any hardware and software, or the part that performs determination and the part that performs control may be configured separately. The rail break and train detection systems 10 having the above-described configuration and arrangement as shown in FIG. 1 are installed consecutively along the direction in which the rail extends, to monitor the entire monitored area of ​​the railway line.

[0034] Next, referring to FIG. 2, a description will be given of the current path of an AC signal when a train 60 is present on the track or when a rail break occurs in the configuration shown in FIG. 1. First, FIG. 2(a) illustrates a state in which a train 60 is present on the track in the first region LT of the second rail pair 54. In this state, the axles of the train 60 short-circuit the rails 55 and 56 of the second rail pair 54. Therefore, when an AC signal of the first frequency f1 is transmitted from the transmitter 14, a current path is formed as shown by the arrow indicated by the symbol f1 in FIG. 2(a). That is, the current path runs from the transmitter 14 through the rail 51, the first series resonant circuit unit 22, the rail 55, the train 60, the rail 56, the first series resonant circuit unit 22, and the rail 52, returning to the transmitter 14, but does not reach the receiver 18. As a result, the reception level of the received AC signal of the first frequency f1 confirmed by the receiver 18 is significantly lower than in a normal state. The same applies when the train 60 is located in the first region LT of the first rail pair 50, except that the current path does not pass through the first series resonant circuit unit 22. In contrast, when the train 60 is located in the second region RT of the first rail pair 50 or the second rail pair 54, a current path is formed such that the AC signal of the second frequency f2 transmitted from the transmitter 14 passes through the train 60 and returns to the transmitter 14 without reaching the receiver 18. For this reason, the reception level of the received AC signal of the second frequency f2 confirmed by the receiver 18 is significantly lower than that in the normal state.

[0035] FIG. 2(b) also shows a state in which rail 55 of second rail pair 54 is broken at the portion marked with an x ​​in the first region LT. In this state, due to the break in rail 55 in the first region LT, a current path for AC signals of the first frequency f1 is not formed. Therefore, the reception level of the received AC signals of the first frequency f1 confirmed by the receiver 18 is significantly lower than in the normal state. The same applies when rail 56 of second rail pair 54 and rails 51 and 52 of first rail pair 50 are broken in the first region LT. In contrast, when rails 51 and 52 of first rail pair 50 and rails 55 and 56 of second rail pair 54 are broken in the second region RT, a current path for AC signals of the second frequency f2 is not formed. Therefore, the reception level of the received AC signals of the second frequency f2 confirmed by the receiver 18 is significantly lower than in the normal state.

[0036] Here, a state in which a train 60 is located in the first region LT of the second rail pair 54, as shown in FIG. 2(a), and a state in which a rail 55 of the second rail pair 54 is broken in the first region LT, as shown in FIG. 2(b), have in common the fact that the reception level of the received AC signal of the first frequency f1 is significantly lower than in a normal state. For this reason, the determination control unit 30 determines that a rail break has occurred or that a train 60 is located in the first region LT or the second region RT by comparing the reception level of the received AC signal of the first frequency f1 or the second frequency f2 received by the receiver 18 with a preset reception level threshold. The reception level threshold used in this case will now be described with reference to FIGS. 3 and 4.

[0037] First, Figure 3 is a graph showing the change in reception level, with the vertical axis representing reception level (dB) and the horizontal axis representing train position (m), showing the results of a simulation in which a train 60 is traveling from left to right in the configuration shown in Figure 1. The vertical axis represents reception level, assuming that the reception level under normal conditions, when the train 60 is not on the track and no rail breaks have occurred, is 0 dB. The horizontal axis represents train position, with the positions of transmission point 16 and reception point 20 at 0 m, the left side of Figure 1 representing the negative direction, and the right side of Figure 1 representing the positive direction, and shows the position of the train 60 up to the adjacent tracks on the left and right of the monitored track. In the simulation, the length of the monitored track rail was set to 500 m, and transmission point 16 and reception point 20 were set at the center of the rail. That is, the positions indicated by the balloons labeled "transmission point" on the horizontal axis correspond to the positions (0 m) of the transmission point 16 and the reception point 20, and the two positions indicated by the balloons labeled "short circuit" correspond to the installation positions of the first series resonant circuit unit 22 and the second series resonant circuit unit 26. Also, Fig. 3(a) shows the case where an AC signal of the first frequency f1 is transmitted, and Fig. 3(b) shows the case where an AC signal of the second frequency f2 is transmitted.

[0038] 3(a), the reception level of the AC signal of the first frequency f1 gradually decreases from around 0 dB as the train 60 approaches the monitored track on the adjacent track on the left, and drops to −15.8 dB when the train 60 passes the installation position of the first series resonant circuit unit 22 and enters the first region LT of the monitored track. The reception level further decreases gradually on the way to the transmission point 16 (reception point 20), and when the train 60 passes the installation position of the second series resonant circuit unit 26 and enters the second region RT, the reception level starts to increase, and by the time the train 60 passes the installation position of the second series resonant circuit unit 26 and reaches the adjacent track on the right, the reception level has risen to around −4.0 dB.

[0039] 3(b), the reception level of the received AC signal of the second frequency f2 gradually decreases from around 0 dB as the train 60 approaches the monitored track on the adjacent track on the left, and continues to decrease even when the train 60 passes the installation position of the first series resonant circuit unit 22 and enters the monitored track. Then, when the train 60 passes the transmission point 16 (reception point 20) and enters the second region RT of the monitored track, the reception level drops to -23.6 dB. From there, the reception level then starts to increase, and by the time the train 60 passes the installation position of the second series resonant circuit unit 26 and reaches the adjacent track on the right, the reception level has risen to around -16.5 dB.

[0040] Furthermore, Figure 4 is a graph showing the change in reception level, with the vertical axis representing the reception level (dB) and the horizontal axis representing the break location (m), showing the results of a simulation in which a rail break occurs in the configuration shown in Figure 1. As with the graph in Figure 3, the reception level on the vertical axis is plotted against the reception level of 0 dB under normal conditions when no train 60 is on the track and no rail break has occurred. The horizontal axis represents the break location, with the positions of the transmission point 16 and the reception point 20 at 0 m, the left side of Figure 1 representing the negative direction, and the right side of Figure 1 representing the positive direction, and shows the position of the rail break from the position of the monitored track to the adjacent tracks on the left and right sides. The size of the monitored track and the bubbles on the horizontal axis are the same as those in Figure 3. Figure 4(a) shows the results when an AC signal with a first frequency f1 is transmitted, and Figure 4(b) shows the results when an AC signal with a second frequency f2 is transmitted.

[0041] 4(a), the reception level of the received AC signal of the first frequency f1 is 0 dB or higher when a rail break occurs on the adjacent track on the left, but drops to −12.1 dB when the rail break occurs in the first region LT of the monitored track beyond the installation position of the first series resonant circuit unit 22. Then, while the rail break is located in the first region LT, the reception level remains unchanged, but when the rail break position moves into the second region RT of the monitored track beyond the installation position of the transmission point 16 (reception point 20), the reception level rises to around 2.5 dB and remains the same all the way to the adjacent track on the right beyond the installation position of the second series resonant circuit unit 26.

[0042] 4(b), the reception level of the received AC signal of the second frequency f2 is near 0 dB and near 2.5 dB when a rail break occurs on the adjacent track on the left, and near 3.0 dB when the rail break occurs in the first region LT of the monitored track beyond the installation position of the first series resonant circuit unit 22. Then, when the rail break is located in the second region RT of the monitored track beyond the installation position of the first series resonant circuit unit 22, the reception level drops to -15.6 dB, and remains at this level while the rail break is located in the second region RT. When the rail break is located on the adjacent track on the right beyond the installation position of the second series resonant circuit unit 26, the reception level rises to near 8.0 dB.

[0043] 3 and 4, the reception levels when a train is present or a rail break occurs in each monitoring area are −15.8 dB, −23.6 dB, −12.1 dB, and −15.6 dB, all of which are lower than −10.0 dB. For this reason, although not limited to this, the determination control unit 30 of this embodiment sets −10.0 dB as the reception level threshold (hereinafter also referred to as the “detection state determination threshold”) for determining the presence or absence of a rail break or a train. That is, the determination control unit 30 sets the reception level threshold based on the reception level when a rail break occurs in the determination area and the reception level when a train 60 is present in the determination area, with the reception level when neither a rail break nor a train is present in the determination area (monitored track) being used as a reference.

[0044] Furthermore, the determination control unit 30 sets, taking hysteresis into consideration, a reception level threshold value for transitioning from a state in which a rail break or train is present to a normal state (hereinafter also referred to as the "normal state determination threshold value") of -8.0 dB, which is a value between -10.0 dB and +2.0 dB. Therefore, the determination control unit 30 uses these reception level threshold values ​​to determine whether a rail break or train is present on the monitored track, or whether the monitored track is in a normal state in which neither of these conditions has occurred. Note that in the graphs of Figures 3 and 4, thick dashed lines are drawn at the position of the reception level of -10.0 dB, which is set as the detection state determination threshold value as described above, and at the position of the reception level of -8.0 dB, which is set as the normal state determination threshold value.

[0045] Furthermore, if the determination control unit 30 determines that a rail break or a train is present, it must determine which of the two has occurred. Therefore, the determination control unit 30 distinguishes between a rail break and a train presence based on the degree of change in the reception level of the AC signal received by the receiver 18. To this end, the determination control unit 30 of this embodiment acquires the reception levels of the AC signal a predetermined number of times consecutively at a predetermined cycle from the receiver 18, and uses these as unit data of the reception levels. For example, and not limited to this, the determination control unit 30 acquires the reception levels of the AC signal 32 times consecutively at a cycle of 10 ms (320 ms), and uses the average value of the reception levels of the AC signal for these 32 times as unit data.

[0046] The decision control unit 30 then sequentially calculates the unit data of the reception level as described above. This results in a unit data of the reception level being calculated every 320 ms. Furthermore, the decision control unit 30 calculates the absolute value of the level difference between consecutive unit data, and uses this level difference as the degree of change in the reception level. Figure 5 shows the simulation results of the level difference between consecutive unit data, with the vertical axis representing the level difference (dB) between the previous value and the current value (between consecutive unit data) and the horizontal axis representing time (seconds). Each data point in the graph of Figure 5 is represented by a black circle every 320 ms, and a graph line is drawn along the circle. Figure 5(a) shows the simulation results when a train 60 runs at 260 km / h in the configuration shown in Figure 1, and Figure 5(b) shows the simulation results when a rail break occurs in the configuration shown in Figure 1. The speed setting of 260 km / h in Figure 5(a) was used for simulations under more severe conditions, such as those of a Shinkansen bullet train.

[0047] Referring to FIG. 5(a) when a train 60 is running, the level difference between consecutive unit data when the reception level falls below −10.0 dB, which is set as the detection state determination threshold, is 1.6 dB, and the maximum level difference between consecutive unit data is 4.2 dB. As such, when the train 60 is running, the overall level difference between consecutive unit data does not exceed 5.0 dB, and the reception level changes relatively gradually. Also, referring to FIG. 5(b) when a rail break occurs, the level difference between consecutive unit data when the reception level falls below −10.0 dB, which is set as the detection state determination threshold, is 12.0 dB, which is the maximum value. As such, when a rail break occurs, the reception level changes abruptly.

[0048] Taking this into consideration, in this embodiment, although not limited to this, the threshold value for the level difference between consecutive unit data is set to 5.0 dB, and the determination control unit 30 determines that there is a rail break when the level difference is 5.0 dB or more, and that there is a train on track when the level difference is less than 5.0 dB. In other words, the determination control unit 30 sets a threshold value for the level difference between consecutive unit data in the reception level for distinguishing between a rail break and a train on track, based on the level difference between consecutive unit data when a rail break has occurred in the determination area (monitored track) and the level difference between consecutive unit data when a train 60 is on track in the determination area.

[0049] Next, a method for determining whether a rail break has occurred while the train 60 is traveling in the determination area (monitored track) will be described. The determination control unit 30 generally uses both the determination results for the first area LT and the determination results for the second area RT to determine whether a rail break has occurred while the train 60 is traveling. First, a case where a rail break has occurred while the train 60 is traveling in the first area LT will be described with reference to FIG. 6, using an example in which the rail 55 of the second rail pair 54 breaks in the first area LT. Similar to FIG. 3, FIG. 6(a) is a graph showing the change in reception level, with the vertical axis representing reception level (dB) and the horizontal axis representing train position (m), showing the results of a simulation in which the train 60 is traveling from left to right in FIG. 1 in the configuration shown in FIG. 1. The basic settings of the graph in FIG. 6(a) are the same as those of the graph in FIG. 3. The graph in Fig. 6(a) shows the simulation results for a case in which the rail 55 breaks at a position -150 m in the first region LT while the train 60 is running. In Fig. 6(a), the reception level of the received AC signal of the first frequency f1 is indicated by a dashed line, and the reception level of the received AC signal of the second frequency f2 is indicated by a thick solid line. Furthermore, thick dashed lines are added at the positions of reception levels of -10.0 dB and -8.0 dB, which are set as the detection state determination threshold and the normal state determination threshold, respectively.

[0050] 6(a), the reception level of the first frequency f1 (dashed line) is approximately -16.0 dB when the train 60 enters the first region LT of the monitoring area. It gradually decreases from there, then drops sharply after the rail break occurs. Then, after the train 60 passes transmission point 16 (reception point 20), the reception level begins to rise, but the change is gradual, and it remains below the detection state determination threshold of -10.0 dB even after the train 60 enters the adjacent track on the right. In contrast, the reception level of the second frequency f2 (thick solid line) falls below the detection state determination threshold of -10.0 dB while the train 60 is traveling through the first region LT, and continues to decrease with increasing change as the train 60 advances. By the time the train 60 reaches transmission point 16 (reception point 20) and enters the second region RT, the reception level is approximately -42.5 dB. Then, the reception level starts to rise, rising sharply, then gradually increases and continues to rise. When train 60 enters the adjacent track on the right, the increase in the reception level becomes larger and continues to exceed the normal state determination threshold.

[0051] Among the changes in reception level described above, we focus here on the changes in the enclosed areas marked with symbols A, B, and C in FIG. 6(a). Specifically, enclosed area A corresponds to the timing when the reception level of the received AC signal at the first frequency f1, indicated by the dashed line, falls below the detection state threshold of −10.0 dB. Furthermore, although not shown, the level difference between consecutive unit data at this time is smaller than 5.0 dB, the threshold for the difference in reception level used to distinguish between a rail break and a train presence. Therefore, the determination control unit 30 determines that the first region LT has entered a train presence state. Furthermore, at the same timing as enclosed area A, the reception level of the received AC signal at the second frequency f2, indicated by the thick solid line, does not fall below the detection state threshold of −10.0 dB, so the determination control unit 30 determines that the second region RT is in a normal state. These state changes and determination details are shown in item A in the table in FIG. 6(b).

[0052] The enclosed area B corresponds to the timing when the reception level of the received AC signal of the second frequency f2, indicated by the thick solid line, falls below the detection state threshold of −10.0 dB. Furthermore, although not shown in the figures, the level difference between consecutive unit data at this time is smaller than 5.0 dB, the threshold for the difference in reception level used to distinguish between a rail break and a train presence. Therefore, the determination control unit 30 determines that the second area RT has entered a train presence state. At the same timing as the enclosed area B, the reception level of the received AC signal of the first frequency f1, indicated by the dashed line, remains below the detection state threshold of −10.0 dB, so the determination control unit 30 determines that the first area LT remains in a train presence state. These state changes and determination details are shown in item B of the table in FIG. 6(b).

[0053] Furthermore, the enclosed portion C is the timing when the reception level of the received AC signal of the second frequency f2, indicated by the thick solid line, exceeds the normal state determination threshold of −8.0 dB. Therefore, the determination control unit 30 determines that the second region RT has entered the normal state. Also, at the same timing as the enclosed portion C, the reception level of the received AC signal of the first frequency f1, indicated by the dashed line, remains below the detection state determination threshold of −10.0 dB. However, as determined for the second region RT, it is considered that the train 60 has already moved from the second region RT to the adjacent track on the right.

[0054] In light of the above, the determination control unit 30 of this embodiment determines that a rail break has occurred in the first region LT while the train 60 is traveling on the first rail pair 50 or the second rail pair 54 from one side to the other in the rail extension direction (from left to right in FIG. 1 ) in the following cases: That is, the determination control unit 30 sequentially determines that the train 60 is present in the first region LT and the second region RT, and then determines that the train 60 has changed from its present state in the second region RT to its normal state (not present in the second region RT), but continues to determine that the train 60 is present in the first region LT. Such state changes and determination details are shown in item C of the table in FIG. 6(b). The determination that a rail break has occurred in the second region RT while the train 60 is traveling from the other side to one side in the rail extension direction (from right to left in FIG. 1 ) can be made by replacing the first region LT with the second region RT in the above conditions.

[0055] Next, a case where a rail break occurs while the train 60 is traveling in the second region RT will be described with reference to FIG. 7, taking as an example a case where the rail 55 of the second rail pair 54 breaks in the second region RT. FIG. 7(a) shows the results of a simulation under the same conditions as those shown in FIG. 6(a), except that the rail break occurred at a position 150 m into the second region RT rather than the first region LT. In FIG. 7(a) as well, the reception level of the received AC signal of the first frequency f1 is shown by a dashed line, and the reception level of the received AC signal of the second frequency f2 is shown by a thick solid line. Thick dashed-dot lines are also added at the reception levels of −10.0 dB and −8.0 dB, which are set as the detection state determination threshold and the normal state determination threshold, respectively.

[0056] 7(a), the reception level of the second frequency f2, indicated by the thick solid line, falls below the detection state determination threshold of −10.0 dB while the train 60 is traveling through the first region LT, and continues to fall while the change becomes larger as the train 60 travels further, reaching approximately −23.0 dB by the time the train 60 reaches transmission point 16 (reception point 20) and enters the second region RT. From there, the reception level begins to rise gradually, increasing in speed around the time a rail break occurs, but then slows down again, and the reception level remains below the detection state determination threshold of −10.0 dB even when the train 60 enters the adjacent track on the right. In contrast, the reception level of the first frequency f1, indicated by the dashed line, is approximately -16.0 dB when the train 60 enters the first region LT of the monitoring area, and then gradually decreases to approximately -23.0 dB when the train 60 passes the transmission point 16 (reception point 20).The reception level then begins to rise, and the increase becomes more pronounced when a rail break occurs, at which point it exceeds the normal state determination threshold of -8.0 dB.

[0057] Among the changes in reception level described above, we focus here on the changes in the enclosed areas marked with symbols A and B in FIG. 7(a). Specifically, enclosed area A corresponds to the timing when the reception level of the received AC signal of the second frequency f2, indicated by the thick solid line, falls below the detection state determination threshold of −10.0 dB. Furthermore, although not shown, the level difference between consecutive unit data at this time is smaller than 5.0 dB, the threshold for the difference in reception level used to distinguish between a rail break and a train presence. Therefore, the determination control unit 30 determines that the second region RT has entered a train presence state. Furthermore, at the same timing as enclosed area A, the reception level of the received AC signal of the first frequency f1, indicated by the dashed line, remains below the detection state threshold of −10.0 dB, and the level difference between consecutive unit data is smaller than 5.0 dB. Therefore, the determination control unit 30 determines that the first region LT remains in a train presence state. Such state changes and determination details are shown in item A of the table in FIG. 7(b).

[0058] Also, the enclosed portion B is the timing when the reception level of the received AC signal of the first frequency f1, indicated by the dashed line, exceeds the normal state determination threshold of -8.0 dB. Therefore, the determination control unit 30 determines that the first region LT has entered the normal state. Furthermore, at this time, the reception level of the received AC signal of the first frequency f1 changes sharply, and although not shown, the level difference between consecutive unit data is 5.0 dB or more. Furthermore, in the enclosed portion B, the reception level of the received AC signal of the second frequency f2, indicated by the thick solid line, remains below the detection state determination threshold of -10.0 dB.

[0059] Based on the above, the determination control unit 30 of this embodiment determines that a rail break has occurred in the second region RT while the train 60 is traveling on the first rail pair 50 or the second rail pair 54 from one side to the other in the rail extension direction (from left to right in FIG. 1 ) in the following cases: That is, the determination control unit 30 determines that the train 60 is on the tracks in both the first region LT and the second region RT, and then determines that the train 60 has changed to a non-on-track state in the first region LT, and the degree of change in the reception level of the received AC signal (at the first frequency f1) for the first region LT at that time is equal to or greater than a preset threshold value for the degree of change, and the determination control unit 30 continues to determine that the train 60 is on the tracks in the second region RT. In this embodiment, although not limited to this, the threshold value for the degree of change is set to 5.0 dB obtained from simulation results in the determination control unit 30. Such state changes and determination contents are shown in item B of the table in FIG. 7(b). To determine whether a rail break has occurred in the first region LT while the train 60 is traveling from the other side to one side in the rail extension direction (from the right side to the left side in Figure 1), the first region LT and the second region RT in the above conditions can be read interchangeably.

[0060] The state transition diagram in Figure 8 shows the conditions under which the first region LT and the second region RT transition to either the normal state, the train detection state, or the rail break detection state as determined by the determination control unit 30 when a train 60 travels from left to right in Figure 1. Briefly, when the rail break and train detection system 10 is first started up, the system is set to the train detection state, taking fail-safe measures into consideration. From there, if the reception level of the received AC signal at the first frequency f1 or the second frequency f2 exceeds the normal state determination threshold of -8.0 dB, the system transitions to the normal state. If the reception level remains below the detection state threshold of -10.0 dB, the system remains in the train detection state.

[0061] In the train detection state in the first region LT, both the first region LT and the second region RT are monitored. If the reception level of the AC signal of the first frequency f1 for the first region LT remains below the detection state threshold of −10.0 dB even when the second region RT has transitioned from the train detection state (train present) to the normal state (train not present), it is determined that a rail break has occurred in the first region LT and the state transitions to the rail break detection state. Furthermore, in the train detection state in the second region RT, both the first region LT and the second region RT are monitored. If the first region LT transitions from the train detection state to the normal state and the level difference between consecutive unit data (previous value − current value) at that time is 5.0 dB or more and the reception level of the AC signal of the second frequency f2 for the second region RT remains below the detection state threshold of −10.0 dB, it is determined that a rail break has occurred in the second region RT and the state transitions to the rail break detection state.

[0062] From the normal state, the normal state is maintained as long as the reception level of the received AC signal of the first frequency f1 or the second frequency f2 remains above the normal state determination threshold of -8.0 dB. Also, in the normal state, if the reception level falls below the detection state determination threshold of -10.0 dB and the level difference between consecutive unit data (previous value - current value) is less than 5.0 dB, the threshold for distinguishing between train detection and rail break detection, the state transitions to the train detection state. Furthermore, in the normal state, if the reception level falls below the detection state determination threshold of -10.0 dB and the level difference between consecutive unit data (previous value - current value) is greater than 5.0 dB, the threshold for distinguishing between train detection and rail break detection, the state transitions to the rail break detection state.

[0063] From the rail break detection state, if the reception level of the received AC signal of the first frequency f1 or the second frequency f2 rises above the normal state judgment threshold of -8.0 dB due to repair of the broken rail or the like, the system transitions to the normal state. Also, in the rail break detection state, if the reception level remains below the detection state judgment threshold of -10.0 dB, the system remains in the rail break detection state. Note that in Figure 8, the transition from the rail break detection state to the train detection state is indicated by a dashed arrow, but this indicates that such a transition is not taken into consideration because the train 60 will not be allowed to run in a state where a rail break has been detected.

[0064] Here, the rail break and train detection system 10 according to the embodiment of the present invention described above is not limited to the configurations shown in FIGS. 1 to 8, but can have various configurations depending on the situation, application, and the like. For example, the rail break and train detection system 10 may include components other than those shown in FIG. 1, and the equipment used for each component may be any material that satisfies the functions required for each component. Furthermore, the threshold values ​​used for judgment are not limited to those derived by simulation, and may also or alternatively depend on experimental results. Furthermore, the specific numerical values ​​used in each explanation are merely examples and do not limit the scope of the present invention, and various values ​​may be used.

[0065] The embodiment of the present invention configured as described above can achieve the following advantageous effects. Specifically, as shown in FIG. 1 , a rail break and train detection system 10 according to the embodiment of the present invention is for detecting both a rail break and a train on a railway line including a first rail pair 50 and a second rail pair 54, and includes a transmitter 14, a receiver 18, a first series resonant circuit unit 22, a second series resonant circuit unit 26, and a determination controller 30. The transmitter 14 transmits AC signals to the first rail pair 50 and is capable of transmitting both AC signals at a first frequency f1 and an AC signal at a second frequency f2. The receiver 18 receives AC signals from the second rail pair 54 near the transmitter 14, more specifically, near a location where the transmitter 14 transmits AC signals to the first rail pair 50. That is, the transmitter 14 and receiver 18 are installed so that the point 16 of transmission from the transmitter 14 to the first pair of rails 50 and the point 20 of reception from the receiver 18 to the second pair of rails 54 are close to each other.

[0066] The first series resonant circuit unit 22 has a resonant circuit with a resonant frequency of the first frequency f1 so as to pass only AC signals of the first frequency f1 transmitted from the transmitter 14. The first series resonant circuit unit 22 is installed at a position away from the transmitter 14 and the receiver 18 on one side in the rail extension direction (the left side in FIG. 1 ) to connect the first rail pair 50 and the second rail pair 54. In contrast, the second series resonant circuit unit 26 has a resonant circuit with a resonant frequency of the second frequency f2 so as to pass only AC signals of the second frequency f2 transmitted from the transmitter 14. The second series resonant circuit unit 26 is installed at a position away from the transmitter 14 and the receiver 18 on the other side in the rail extension direction (the right side in FIG. 1 ) to connect the first rail pair 50 and the second rail pair 54. That is, the first pair of rails 50 and the second pair of rails 54 are connected by a first series resonant circuit unit 22 at a position separated on one side of the rail extension direction, and by a second series resonant circuit unit 26 at a position separated on the other side of the rail extension direction, sandwiched between a transmission point 16 to the first pair of rails 50 by the transmitter 14 and a reception point 20 from the second pair of rails 54 by the receiver 18.

[0067] The determination control unit 30 performs determination using a first region LT and a second region RT as determination regions. Here, the first region LT is the region between the connection point of the first series resonant circuit unit 22 of the first rail pair 50 and the second rail pair 54 and the transmission point 16 and the reception point 20. The second region RT is the region between the connection point of the second series resonant circuit unit 26 of the first rail pair 50 and the second rail pair 54 and the transmission point 16 and the reception point 20. Furthermore, the determination control unit 30 performs determination based on the received AC signal received by the receiving unit 18 from the second rail pair 54. That is, when an AC signal of the first frequency f1 is transmitted from the transmitting unit 14, it is received by the receiving unit 18 via the first series resonant circuit unit 22, and therefore, the determination is performed on the AC signal passing through the first region LT. Therefore, when the AC signal received by the receiving unit 18 is an AC signal of the first frequency f1, the determination control unit 30 makes a determination about the first region LT based on the received AC signal. On the other hand, when an AC signal of the second frequency f2 is transmitted from the transmitting unit 14, the AC signal is received by the receiving unit 18 via the second series resonant circuit unit 26, and therefore the determination is made about the AC signal passing through the second region RT. Therefore, when the AC signal received by the receiving unit 18 is an AC signal of the second frequency f2, the determination control unit 30 makes a determination about the second region RT based on the received AC signal.

[0068] More specifically, the determination control unit 30 compares the reception level of the received AC signal of the first frequency f1 or the second frequency f2 with a preset threshold value for the reception level to determine whether a rail break or a train is present, as shown in FIG. 2 . Furthermore, if the determination control unit 30 determines that either a rail break or a train is present, it distinguishes between the rail break and the presence of a train based on the degree of change in the reception level of the received AC signal. That is, the inventors have found that there is a difference between the degree of change in the reception level of the received AC signal when a rail break occurs and the degree of change in the reception level of the received AC signal when a train 60 (see FIG. 2(a)) is present on the track, and this difference is used to distinguish between the rail break and the presence of a train. Specifically, when a rail break occurs, the reception level of the received AC signal tends to change abruptly (see FIG. 4 ), whereas when a train 60 is present on the track, the reception level of the received AC signal tends to change more gradually (see FIG. 3 ). This makes it possible to achieve both rail breakage detection and train detection while keeping costs down with an inexpensive configuration that follows the track circuit system.

[0069] Furthermore, in the rail break and train detection system 10 according to the embodiment of the present invention, the threshold value of the reception level preset in the determination control unit 30 is set taking into account values ​​obtained from simulations and / or experiments. Specifically, as shown in FIGS. 3 and 4 , the reception levels of the AC signals received by the receiver 18 are determined from simulations and / or experiments for each of the following states: a state in which a rail break has occurred in the determination area; a state in which a train 60 is present in the determination area; and a state in which neither a rail break nor a train is present in the determination area. Then, based on the reception levels of these AC signals, the determination control unit 30 sets a threshold value of the reception level (−10.0 dB in the illustrated example) for determining whether a rail break or a train is present. This allows for accurate determination of the presence or absence of a rail break or a train.

[0070] Furthermore, in the rail break and train detection system 10 according to the embodiment of the present invention, the determination control unit 30 determines and uses unit data of the reception level when distinguishing between a rail break and a train presence. That is, the reception AC signal is acquired from the receiver 18 a predetermined number of times in a predetermined cycle, and the reception level of the reception AC signal for the predetermined number of times is used as unit data. The predetermined cycle and the predetermined number of times are set taking into consideration ease of calculation, and in this embodiment, the predetermined cycle is 10 ms and the predetermined number of times is 32 times. The determination control unit 30 then uses the determined unit data to calculate the level difference between consecutive unit data and uses this level difference as the degree of change in the reception level of the reception AC signal for distinguishing between a rail break and a train presence. This enables efficient and accurate distinguishing between a rail break and a train presence.

[0071] Furthermore, in the rail break and train detection system 10 according to the embodiment of the present invention, when the judgment control unit 30 distinguishes between a rail break and a train presence on the track, the distinction is made using a threshold value for the level difference between consecutive unit data as described above. That is, for each of a state in which a rail break has occurred in the judgment area and a state in which a train 60 is present on the track in the judgment area, the level difference between consecutive unit data is determined through simulation and / or experiment (see FIG. 5). Then, based on these level differences, a level difference threshold value (5.0 dB in the illustrated example) is set for the judgment control unit 30 to distinguish between a rail break and a train presence on the track. This allows for more accurate distinction between a rail break and a train presence on the track.

[0072] Furthermore, in the rail break and train detection system 10 according to the embodiment of the present invention, the determination control unit 30 determines whether a rail break has occurred while the train 60 is traveling. It is expected that if a rail break occurs while the train 60 is traveling, the reception level of the AC signal received by the receiver 18 will exhibit more characteristic behavior than when either the train 60 is present on the track or a rail break occurs. Therefore, the determination control unit 30 normally uses the determination results in the first region LT and the second region RT separately, but determines whether a rail break has occurred while the train 60 is traveling by combining these two determination results. The determination results here may include the results of the determination of the presence or absence of a rail break or a train on the track in the first region LT and the second region RT, the distinction between them, the reception level of the AC signal, etc. This allows for a smooth determination even when a rail break occurs while the train 60 is traveling.

[0073] The rail break and train detection system 10 according to the embodiment of the present invention determines that a rail break has occurred in the first area LT when the train 60 is traveling on the first rail pair 50 or the second rail pair 54 from one side to the other in the rail extension direction, in other words, from the first area LT to the second area RT, as follows. That is, as shown in FIG. 6 , the determination control unit 30 sequentially determines that the train 60 is located in the first area LT and then in the second area RT. If the determination control unit 30 subsequently determines that the train 60 has changed from being located in the second area RT to not being located in the second area RT, but continues to determine that the train 60 is located in the first area LT, the determination control unit 30 determines that a rail break has occurred in the first area LT. This makes it possible to easily determine that a rail break has occurred in the first area LT while the train 60 is traveling in the direction from the first area LT to the second area RT.

[0074] Furthermore, the rail break and train detection system 10 according to the embodiment of the present invention determines that a rail break has occurred in the second area RT when the train 60 is traveling on the first rail pair 50 or the second rail pair 54 from one side to the other in the rail extension direction, in other words, from the first area LT to the second area RT, as follows: That is, as shown in Fig. 7, the determination control unit 30 determines that the train 60 is on the tracks in both the first area LT and the second area RT, and then determines that the train 60 has changed to an off-track state in the first area LT, and determines that a rail break has occurred in the second area RT if the degree of change in the reception level of the received AC signal at that time is equal to or greater than a preset threshold value for the degree of change (5.0 dB in the illustrated example) and the determination that the train 60 is on the tracks continues in the second area RT. This makes it possible to determine without any problem that a rail break has occurred in the second area RT while the train 60 is traveling in the direction from the first area LT to the second area RT.

[0075] On the other hand, the rail break and train detection method according to the embodiment of the present invention can be implemented using the rail break and train detection system 10 according to the embodiment of the present invention as described above, thereby achieving the same effects as those of the rail break and train detection system 10 according to the embodiment of the present invention. [Explanation of symbols]

[0076] 10: Rail break and train detection system, 14: Transmitter, 18: Receiver, 22: First series resonant circuit, 26: Second series resonant circuit, 30: Judgment control unit, 50: First rail pair, 54: Second rail pair, 60: Train, LT: First region, RT: Second region, f1: First frequency, f2: Second frequency

Claims

1. 1. A system for detecting rail breaks and trains on a railway line including first and second pairs of rails laid in parallel, comprising: a transmitter that transmits an AC signal of a first frequency and an AC signal of a second frequency to the first pair of rails; a receiving section that receives AC signals from the second pair of rails in the vicinity of the transmitting section; a first series resonant circuit unit that connects the first rail pair and the second rail pair at a position away from the transmitter and the receiver on one side in the rail extension direction and has the first frequency as a resonant frequency; a second series resonant circuit unit that connects the first rail pair and the second rail pair at a position away from the transmitter and the receiver on the other side in the rail extension direction and has the second frequency as a resonant frequency; a determination control unit that determines a first region between a connection point of the first series resonant circuit unit and a connection point of the transmitter and the receiver of the first rail pair and a second region between a connection point of the second series resonant circuit unit and a connection point of the transmitter and the receiver of the second rail pair as a determination region based on a reception AC signal received by the receiver, The judgment control unit compares the reception level of the received AC signal with a preset threshold value for reception level to judge whether there is a rail break or a train on the track, and distinguishes between a rail break and a train on the track based on the degree of change in the reception level of the received AC signal.

2. 2. The rail break and train detection system according to claim 1, wherein the threshold value is set based on a reception level of the received AC signal when a rail break has occurred in the judgment area, a reception level of the received AC signal when a train is present in the judgment area, and a reception level of the received AC signal when neither a rail break nor a train is present in the judgment area, which are obtained from simulations and / or experiments.

3. 2. The rail break and train detection system according to claim 1, wherein the determination control unit uses a predetermined period and a predetermined number of times that are set in advance, and calculates a level difference between successive unit data pieces, using the reception level of the received AC signal acquired continuously for the predetermined number of times at the predetermined period as unit data, and uses the level difference as a degree of change in the reception level.

4. 4. The rail break and train detection system according to claim 3, wherein the determination control unit distinguishes between a rail break and a train being present on the track using a level difference threshold value set based on the level difference when a rail break has occurred in the determination area and the level difference when a train is present in the determination area, the level difference being obtained from simulations and / or experiments.

5. 2. The rail break and train detection system according to claim 1, wherein the determination control unit uses both the determination result in the first area and the determination result in the second area to determine whether a rail break has occurred while the train is running.

6. 6. The rail break and train detection system according to claim 5, wherein, when a train is traveling on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, the determination control unit sequentially determines that a train is present in the first area and the second area, and then determines that a train has changed from being present in the second area to not being present in the second area, but continues to determine that a train is present in the first area.

7. 6. The rail break and train detection system according to claim 5, wherein, when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, the determination control unit determines that a train is present in both the first area and the second area, and then determines that a train has changed to a non-presence state in the first area, and determines that a rail break has occurred in the second area if the degree of change in the reception level of the received AC signal at that time is equal to or greater than a predetermined threshold value for the degree of change and the determination that a train is present in the second area continues.

8. 1. A method for detecting rail breaks and trains on a railway line including first and second pairs of rails laid in parallel, comprising: a transmitter that transmits AC signals of a first frequency and AC signals of a second frequency to the first pair of rails, and a receiver that receives AC signals from the second pair of rails near the transmitter; a first series resonant circuit unit having the first frequency as a resonant frequency, the first rail pair and the second rail pair being connected at a position away from the transmitter unit and the receiver unit on one side in the rail extension direction; a second series resonant circuit unit having the second frequency as a resonant frequency is connected to the first rail pair and the second rail pair at a position away from the transmitter unit and the receiver unit on the other side in the rail extension direction; a first region between the connection point of the first series resonant circuit unit and the connection point of the transmitter and receiver of the first rail pair and a second region between the connection point of the second series resonant circuit unit and the connection point of the transmitter and receiver of the second rail pair as judgment regions, the reception level of the received AC signal received by the receiver is compared with a preset reception level threshold to determine whether there is a rail break or a train on the track, and the rail break and train presence detection method distinguishes between the rail break and the presence of a train on the track based on the degree of change in the reception level of the received AC signal.

9. 9. The rail break and train detection method according to claim 8, wherein the threshold value is set based on a reception level of the received AC signal when a rail break has occurred in the judgment area, a reception level of the received AC signal when a train is present in the judgment area, and a reception level of the received AC signal when neither a rail break nor a train is present in the judgment area, which are obtained from simulation and / or experiment.

10. 9. A rail break and train detection method according to claim 8, wherein a predetermined cycle and a predetermined number of times are used, and the reception level of the received AC signal acquired continuously at the predetermined cycle for the predetermined number of times is used as unit data, and the level difference between successive unit data is calculated and used as the degree of change in the reception level.

11. 11. The rail break and train detection method according to claim 10, wherein a rail break is distinguished from a train being present on the track by using a level difference threshold value set based on the level difference obtained from simulations and / or experiments when a rail break has occurred in the determination area and the level difference when a train is present on the track in the determination area.

12. 9. A rail break and train detection method according to claim 8, wherein the determination result in the first area and the determination result in the second area are used to determine whether a rail break has occurred while the train is running.

13. 13. The rail break and train detection method according to claim 12, wherein, when a train is running on the first pair of rails or the second pair of rails from one side to the other side in the rail extension direction, it is determined sequentially that a train is present in the first area and the second area, and then, if it is determined that a train has changed from being present in the second area to not being present in the second area but it continues to be determined that a train is present in the first area, it is determined that a rail break has occurred in the first area.

14. 13. The rail break and train detection method according to claim 12, wherein, when a train is running on the first rail pair or the second rail pair from the one side to the other side in the rail extension direction, it is determined that a train is present in both the first area and the second area, and then it is determined that a train has changed to a non-presence state in the first area, and if the degree of change in the reception level of the received AC signal at that time is equal to or greater than a predetermined threshold value for the degree of change and it continues to be determined that a train is present in the second area, it is determined that a rail break has occurred in the second area.

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