Rail state monitoring apparatus

A rail state monitoring apparatus (1) includes: first and second transmission antennas (101, 102) to transmit first and second electric signals to rails (5, 6), respectively; first reception antenna (201) to receive a surface wave (21) of the first electric signal propagated through rail (5) and guided wave (32) of the second electric signal propagated through loop coil (10); second reception antenna (202) to receive surface wave (22) of the second electric signal propagated through rail (6) and guided wave (31) of the first electric signal propagated through loop coil (10); and a processor. The processor obtains received powers of the respective electric signals received by first and second reception antennas (201, 202), determines a rail state from “good”, “rail broken”, “rail crack”, or “rail surface anomaly” based on the received powers, and outputs the rail state as rail state information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rail state monitoring apparatus for detecting a state of a rail.

2. Description of the Related Art

A related-art rail state monitoring apparatus described in Japanese Patent Application Laid-open No. 2002-294609 includes a signal transmitter, a processor, and a signal receiver. An electric signal transmitted from the signal transmitter is input to a first axle disposed on the front side of a vehicle. The electric signal input to the first axle is propagated to a second axle disposed on the rear side of the vehicle through left and right rails. The electric signal propagated to the second axle is received by the signal receiver. The processor constantly accumulates a received power of the electric signal received by the signal receiver. The processor determines that a rail breakage has occurred when the received power drops.

In the rail state monitoring apparatus disclosed in Japanese Patent Application Laid-open No. 2002-294609, the processor determines whether a rail breakage has occurred based on the received power of the electric signal that has been propagated through the rails. However, when rust on a rail or other such rail surface anomaly has occurred, there is a fear that an electrical contact failure may occur between a rail and a wheel. Even in such a case, an electric signal is not propagated, which leads to a problem that the processor cannot distinguish between a rail surface anomaly and a rail breakage, to thereby erroneously determine that a rail breakage has occurred.

SUMMARY OF THE INVENTION

The present invention has been made in order to solve the above-mentioned problem, and has an object to obtain a rail state monitoring apparatus that suppresses erroneous determination as a rail breakage.

According to one embodiment of the present invention, a rail state monitoring apparatus is provided, including: a transmission antenna, which is disposed on a vehicle, and is configured to transmit at least one of a first electric signal, which is to be transmitted to a first rail of a pair of rails, or a second electric signal, which is to be transmitted to a second rail of the pair of rails; a reception antenna, which is disposed on the vehicle, and is configured to receive: at least one of the first electric signal propagated through the first rail or the second electric signal propagated through the second rail; and at least one of the first electric signal propagated through an annular transmission line formed so as to include the first rail and the second rail or the second electric signal propagated through the annular transmission line; and a processor, wherein the processor is configured to: set a first threshold value and a second threshold value smaller than the first threshold value in advance; calculate received powers of the first electric signal and the second electric signal, which are received by the reception antenna; classify each of the received powers as one of three levels of “high”, “medium”, and “low” in comparison with the first threshold value and the second threshold value, and generate a received power pattern; and determine each of rail states of the first rail and the second rail as at least anyone of “good”, “rail broken”, “rail crack”, or “rail surface anomaly” based on the generated received power pattern, and output a result of the determination as rail state information.

With the rail state monitoring apparatus according to one embodiment of the present invention, it is possible to suppress erroneous determination as a rail breakage.

DESCRIPTION OF THE EMBODIMENTS

In the following description, like components are denoted by like reference numerals/symbols.

First Embodiment

FIG. 1andFIG. 2are diagrams for schematically illustrating a configuration of a rail state monitoring apparatus1according to a first embodiment of the present invention.FIG. 1is a plan view, andFIG. 2is a side view.

As illustrated inFIG. 1andFIG. 2, the rail state monitoring apparatus1is mounted to a vehicle2, for example, a railway vehicle. The vehicle2includes a pair of front wheels3and a pair of rear wheels4. The vehicle2uses the front wheels3and the rear wheels4to travel on two rails5and6. The rail5and the rail6are laid in parallel with each other across a gap set in advance. The pair of front wheels3are coupled to each other via a wheel axle7so as to fit the gap between the rail5and the rail6. In the same manner, the pair of rear wheels4are coupled to each other via a wheel axle8so as to fit the gap between the rail5and the rail6. The vehicle2is coupled to at least one other vehicle2to travel as a train.

The rail state monitoring apparatus1includes a first transmission antenna101, a second transmission antenna102, a first reception antenna201, a second reception antenna202, a transmitting unit301, a receiving unit401, an analyzing unit501, and an information transmitting unit601.

The first transmission antenna101, the second transmission antenna102, the first reception antenna201, and the second reception antenna202are mounted under the floor of the vehicle2so as to be located between the front wheels3and the rear wheels4.

The first transmission antenna101and the first reception antenna201are mounted above the rail5along a longitudinal direction of the rail5with an interval set in advance. In the same manner, the second transmission antenna102and the second reception antenna202are mounted above the rail6along a longitudinal direction of the rail6with an interval set in advance.

The first transmission antenna101transmits an electric signal to the rail5. The second transmission antenna102transmits an electric signal to the rail6. Meanwhile, the first reception antenna201receives the electric signal propagated through the rail5or the electric signal propagated through an annular transmission line formed so as to include the rail5and the rail6. The second reception antenna202receives the electric signal propagated through the rail6or the electric signal propagated through the annular transmission line formed so as to include the rail5and the rail6.

The transmitting unit301is connected to the first transmission antenna101and the second transmission antenna102. The transmitting unit301generates a first electric signal to output the first electric signal to the first transmission antenna101, and generates a second electric signal to output the second electric signal to the second transmission antenna102.

The receiving unit401is connected to the first reception antenna201and the second reception antenna202. The receiving unit401calculates received powers and phases of the first electric signal and the second electric signal, which are received by the first reception antenna201and the second reception antenna202. The receiving unit401may calculate only the received powers, or may calculate only the phases.

The analyzing unit501is connected to the receiving unit401. The analyzing unit501compares the received powers calculated by the receiving unit401with two threshold values, to thereby classify the received powers into three levels of “high”, “medium”, and “low” to generate a received power pattern. The analyzing unit501determines the states of the rail5and the rail6based on the generated received power pattern. The analyzing unit501outputs the determined rail state as rail state information.

The information transmitting unit601is connected to the analyzing unit501. The information transmitting unit601transmits the rail state information received from the analyzing unit501to a ground apparatus disposed in the outside. The ground apparatus is described later in a third embodiment of the present invention.

The mounting positions of the transmitting unit301, the receiving unit401, the analyzing unit501, and the information transmitting unit601may be freely-selected positions located in the vehicle2, and are not particularly limited.

Next, an operation of the rail state monitoring apparatus1according to the first embodiment is described.

The transmitting unit301generates a first electric signal of a first frequency and a first amplitude, which are set in advance, and outputs the first electric signal to the first transmission antenna101. Meanwhile, the transmitting unit301generates a second electric signal of a second frequency and a second amplitude, which are set in advance, and outputs the second electric signal to the second transmission antenna102.

At this time, the transmitting unit301employs a multiplexing technology for the first electric signal and the second electric signal so as to prevent the first electric signal and the second electric signal from interfering with each other. Specifically, the first frequency of the first electric signal and the second frequency of the second electric signal are set to have frequency values different from each other. In another case, the transmitting unit301subjects the first electric signal and the second electric signal to code modulation or frequency modulation through use of codes different from each other. In further another case, the transmitting unit301controls the first transmission antenna101and the second transmission antenna102to transmit the first electric signal and the second electric signal by time division. The multiplexing technology is not limited to those technologies, and another multiplexing technology may be employed.

When received the input of the first electric signal from the transmitting unit301, the first transmission antenna101outputs the first electric signal to the rail5. When receiving the input of the second electric signal from the transmitting unit301, the second transmission antenna102outputs the second electric signal to the rail6. As a result, the first electric signal is propagated through the rail5, and the second electric signal is propagated through the rail6. At this time, a propagation path is changed between a case in which the rail5and the rail6are in a good state and a case in which an anomaly of some kind has occurred in the rail5or the rail6. Details thereof are described below.

First, a description is given for propagation paths of the first electric signal and the second electric signal exhibited when the rail5and the rail6are in a good state.FIG. 3andFIG. 4are each an explanatory diagram of a propagation path of an electric signal exhibited when the rails are in a good state. A propagation behavior of the first electric signal and a propagation behavior of the second electric signal are basically the same, and hence the following description is given mainly for the first electric signal.

When receiving the input of the first electric signal from the transmitting unit301, the first transmission antenna101outputs the first electric signal to the rail5. At this time, waves in two different propagation modes are propagated through the rail5. The wave in one propagation mode is illustrated inFIG. 3, and the wave in the other propagation mode is illustrated inFIG. 4.

As illustrated inFIG. 3, the wave in the one propagation mode is a surface wave21propagated on the rail5. In the following description, the surface wave21propagated on the rail5is referred to as “first surface wave21”, and a surface wave propagated on the rail6is referred to as “second surface wave22”. The first surface wave21is a surface wave corresponding to the first electric signal, and is propagated on the rail5without being propagated on the rail6. The second surface wave22is a surface wave corresponding to the second electric signal, and is propagated on the rail6without being propagated on the rail5.

Meanwhile, as illustrated inFIG. 4, the wave in the other propagation mode is a guided wave propagated through a loop coil10. The loop coil10is an annular transmission line including the rail5, the rail6, the wheel axle7, and the wheel axle8. In the following description, the guided wave corresponding to the first electric signal output from the first transmission antenna101is referred to as “first guided wave31”, and the guided wave corresponding to the second electric signal output from the second transmission antenna102is referred to as “second guided wave32”.

When a rail breakage, rust, or other such rail surface anomaly has occurred in the rail5or the rail6, a contact failure occurs between the wheels3and4and the rails5or6. As a result, the loop coil10is disconnected, or an impedance of the loop coil10is changed. Therefore, propagation states of the surface wave21and the surface wave22and propagation states of the guided wave31and the guided wave32are changed. In the first embodiment, the analyzing unit501detects the changes of the propagation states, to determine the states of the rail5and the rail6.

The first electric signal is propagated on the rail5as the first surface wave21as illustrated inFIG. 3, and is propagated through the loop coil10as the first guided wave31as illustrated inFIG. 4.

The first surface wave21is propagated on the rail5to reach a location at which the first reception antenna201is mounted. Meanwhile, the first guided wave31is propagated through the loop coil10to reach not only the location at which the first reception antenna201is mounted but also a location at which the second reception antenna202is mounted.

In the same manner, the second electric signal output from the second transmission antenna102is propagated on the rail6as the second surface wave22as illustrated inFIG. 3, and is propagated through the loop coil10as the second guided wave32as illustrated inFIG. 4.

The second surface wave22is propagated on the rail6to reach a location at which the second reception antenna201is mounted. Meanwhile, the second guided wave32is propagated through the loop coil10to reach not only the location at which the second reception antenna202is mounted but also a location at which the first reception antenna201is mounted.

The first reception antenna201is mounted so as to receive the electric signal propagated through the rail5. Therefore, the first reception antenna201receives the first electric signal propagated as the first surface wave21and the first guided wave31and the second electric signal propagated as the second guided wave32, and outputs the first electric signal and the second electric signal to the receiving unit401.

The second reception antenna202is mounted so as to receive the electric signal propagated through the rail6. Therefore, the second reception antenna202receives the second electric signal propagated as the second surface wave22and the second guided wave32and the first electric signal propagated as the first guided wave31, and outputs the first electric signal and the second electric signal to the receiving unit401.

The receiving unit401calculates the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201, and the received powers of the first electric signal and the second electric signal, which are received by the second reception antenna202.

The analyzing unit501compares the received powers calculated by the receiving unit401with two threshold values, to thereby classify the received powers into the three levels of “high”, “medium”, and “low” to generate a received power pattern.

The received power pattern at a time of a good state is as follows.

First reception antenna201: first electric signal: high

First reception antenna201: second electric signal: high

Second reception antenna202: first electric signal: high

Second reception antenna202: second electric signal: high

The analyzing unit501generates a received power pattern of “high, high, high, and high” by arranging the levels of the received powers of those four electric signals in order, and determines that the rail states of the rail5and the rail6are good based on the received power pattern.

Next, with reference toFIG. 5, a description is given for a propagation path of an electric signal exhibited when a breakage has occurred in the rail5.FIG. 5is an explanatory diagram of a propagation path of an electric signal exhibited when a breakage has occurred in the rail5.

As illustrated inFIG. 5, when receiving the input of the first electric signal, the first transmission antenna101outputs the first electric signal to the rail5. The first electric signal is propagated through the rail5as the first surface wave21. However, a breakage has occurred in the rail5, which inhibits the first surface wave21from reaching the location at which the first reception antenna201is mounted. The loop coil10is also disconnected in the middle due to the breakage of the rail5, which also inhibits the first guided wave31from being propagated to reach the location at which the second reception antenna202is mounted.

When receiving the input of the second electric signal, the second transmission antenna102outputs the second electric signal to the rail6. The second electric signal is propagated through the rail6as the second surface wave22to reach the location at which the second reception antenna202is mounted. However, the loop coil10is also disconnected in the middle due to the breakage of the rail5, which inhibits the second guided wave32from being propagated to reach the location at which the first reception antenna201is mounted.

Therefore, the first reception antenna201receives neither the first electric signal nor the second electric signal, and hence outputs a signal for notifying a non-reception state to the receiving unit401.

Further, the second reception antenna202receives only the second electric signal propagated as the second surface wave22, and outputs only the second electric signal to the receiving unit401.

Therefore, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: low

First reception antenna201: second electric signal: low

Second reception antenna202: first electric signal: low

Second reception antenna202: second electric signal: high

The analyzing unit501determines that a breakage has occurred in the rail5with the rail6being good based on a received power pattern of “low, low, low, and high”.

Next, with reference toFIG. 6, a description is given for an electric signal obtained when a breakage has occurred in the rail6.FIG. 6is an explanatory diagram of a propagation path of an electric signal exhibited when a breakage has occurred in the rail6. Even when a breakage has occurred in the rail6, the electric signal is propagated under the same rule as when a breakage has occurred in the rail5.

Accordingly, the first reception antenna201receives only the first electric signal propagated as the first surface wave21, and outputs only the first electric signal to the receiving unit401.

Further, the second reception antenna202receives neither the first electric signal nor the second electric signal, and hence outputs a signal for notifying a non-reception state to the receiving unit401.

Therefore, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: high

First reception antenna201: second electric signal: low

Second reception antenna202: first electric signal: low

Second reception antenna202: second electric signal: low

The analyzing unit501determines that a breakage has occurred in the rail6with the rail5being good based on a received power pattern of “high, low, low, and low”.

Next, with reference toFIG. 7, a description is given for an electric signal obtained when a breakage has occurred in both the rail5and the rail6. At this time, none of the first surface wave21, the second surface wave22, the first guided wave31, and the second guided wave32is propagated to reach the first reception antenna201and the second reception antenna202.

Therefore, the first reception antenna201receives neither the first electric signal nor the second electric signal, and hence outputs a signal for notifying a non-reception state to the receiving unit401.

Similarly, the second reception antenna202receives neither the first electric signal nor the second electric signal, and hence outputs a signal for notifying a non-reception state to the receiving unit401.

Accordingly, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: low

First reception antenna201: second electric signal: low

Second reception antenna202: first electric signal: low

Second reception antenna202: second electric signal: low

The analyzing unit501determines that a breakage has occurred in the rail5and the rail6based on a received power pattern of “low, low, low, and low”.

Next, with reference toFIG. 8, a description is given for a propagation path of an electric signal exhibited when a crack has occurred in the rail5. At this time, a resistance value of the rail5becomes higher than in the good state due to the occurrence of a crack in the rail5. The first surface wave21propagated through the rail5has a propagation loss larger than in the good rail state due to an increase in resistance value and scattering at a cracked spot. A resistance value of the loop coil10also becomes larger than when the rail is good due to the crack in the rail5. Therefore, a propagation loss of each of the first guided wave31and the second guided wave32becomes larger than in the good rail state.

The first reception antenna201receives the first electric signal and the second electric signal, and outputs the first electric signal and the second electric signal to the receiving unit401. The second reception antenna202receives the first electric signal and the second electric signal and outputs the first electric signal and the second electric signal to the receiving unit401. At this time, the received power of the second electric signal propagated as the second surface wave22to reach the second reception antenna202is the same as at the time of a good state. However, the received power of the other electric signals become smaller than when the rail is good due to an influence of the crack in the rail5, but is larger than the received power exhibited when a breakage has occurred in the rail5.

Therefore, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: medium

First reception antenna201: second electric signal: medium

Second reception antenna202: first electric signal: medium

Second reception antenna202: second electric signal: high

The analyzing unit501determines that a crack has occurred in the rail5with the rail6being good based on a received power pattern of “medium, medium, medium, and high”.

Next, with reference toFIG. 9, a description is given for a propagation path of an electric signal exhibited when a crack has occurred in the rail6. At this time, a resistance value of the rail6becomes higher than in the good state. The second surface wave22propagated through the rail6has a propagation loss larger than in the good rail state due to an increase in resistance value and scattering at a cracked spot. A resistance value of the loop coil10also becomes larger than when the rail is good due to the crack in the rail6. Therefore, a propagation loss of each of the first guided wave31and the second guided wave32becomes larger than in the good rail state.

The first reception antenna201receives the first electric signal and the second electric signal, and outputs the first electric signal and the second electric signal to the receiving unit401. The second reception antenna202receives the first electric signal and the second electric signal and outputs the first electric signal and the second electric signal to the receiving unit401. At this time, the received power of the first electric signal propagated as the first surface wave21to reach the first reception antenna201is the same as at the time of a good state. However, the received power of the other electric signals become smaller than when the rail is good due to an influence of the crack in the rail6, but is larger than the received power exhibited when a breakage has occurred in the rail6.

Therefore, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: high

First reception antenna201: second electric signal: medium

Second reception antenna202: first electric signal: medium

Second reception antenna202: second electric signal: medium

The analyzing unit501determines that a crack has occurred in the rail6with the rail5being good based on a received power pattern of “high, medium, medium, and medium”.

Next, with reference toFIG. 10, a description is given for a case in which rust or foreign matter has adhered to a rail surface of one or both of the rail5and the rail6.FIG. 10is an explanatory diagram of a propagation path of an electric signal exhibited when rust or foreign matter has adhered to the surface of the rail5. In the following description, the adhesion of rust or foreign matter is referred to as “rail surface anomaly”, and a spot at which a rail surface anomaly has occurred is referred to as “anomaly spot”.

InFIG. 10, when the wheel3passes the anomaly spot on the rail5, an electrical contact failure occurs between the wheels3and the rail5. Due to the occurrence of an electrical contact failure, the loop coil10is disconnected or the impedance of the loop coil10is changed, and hence the first guided wave31and the second guided wave32are not propagated, or energy of propagation becomes smaller than when the rail is good. However, the rail5is not broken, and hence the first surface wave21is propagated to reach the first reception antenna201, while the second surface wave22is propagated to reach the second reception antenna202.

The first reception antenna201receives the first electric signal propagated as the first surface wave21, and outputs the first electric signal to the receiving unit401.

The second reception antenna202receives the second electric signal propagated as the second surface wave22, and outputs the second electric signal to the receiving unit401.

Therefore, the received power pattern generated by the analyzing unit501is as follows.

First reception antenna201: first electric signal: high

First reception antenna201: second electric signal: low

Second reception antenna202: first electric signal: low

Second reception antenna202: second electric signal: high

The analyzing unit501determines that a surface anomaly has occurred in at least any one of the rail5or the rail6based on a received power pattern of “high, low, low, and high”.

In this manner, the analyzing unit501subjects the received powers of the first electric signal and the second electric signal to determination using threshold values. The analyzing unit501determines the rail states based on results of the determination using the threshold values. With this determination, the analyzing unit501determines the presence or absence of a rail breakage of any one of the rail5and the rail6, rail breakages of both the rail5and the rail6, a rail crack, and a rail surface anomaly, and outputs the determination result to the information transmitting unit601as rail state information.

The description given above is an example of determining the rail state through use of the received power by the analyzing unit501. However, the present invention is not limited thereto, and the phases of the first electric signal and the second electric signal may be used to determine the rail states. In addition, both the received powers and the phases of the first electric signal and the second electric signal may be used to determine the rail states.

FIG. 11is a table for showing a determination table obtained when the received powers are used for determination. In the determination table, the received power patterns for the rail states are stored on a one-to-one basis.

As described above, the analyzing unit501uses two threshold values to classify the received powers into the three levels of “high”, “medium”, and “low”. That is, a first threshold value Th1 and a second threshold value Th2 smaller than the first threshold value Th1 are set in advance. In this case, a received power equal to or larger than the first threshold value Th1 is set to be “high”, a received power equal to or larger than the second threshold value Th2 but smaller than the first threshold value Th1 is set to be “medium”, and a received power smaller than the second threshold value Th2 is set to be “low”.

As shown in the determination table ofFIG. 11, at the time of a good state, the received powers of the first electric signal and the second electric signal are all “high” at both the first reception antenna201and the second reception antenna202, and hence the received power pattern exhibited at that time is “high, high, high, and high”. Therefore, when the received powers of the first electric signal and the second electric signal are all “high” at both the first reception antenna201and the second reception antenna202, the analyzing unit501generates a received power pattern of “high, high, high, and high”. Then, the analyzing unit501searches the table ofFIG. 11for a received power pattern that matches the generated received power pattern to determine that the rail state is “good”.

Meanwhile, when the rail5is broken, the received power of the second electric signal received by the second reception antenna202is “high”, but the other received powers are all “low”. Therefore, the analyzing unit501searches the table ofFIG. 11for a received power pattern that matches the received power pattern of “low, low, low, and high” to determine that the rail state is “Rail5broken”.

Further, when the rail5is cracked, the received power of the second electric signal received by the second reception antenna202is “high”, but the other received powers are all “medium”. Therefore, the analyzing unit501searches the table ofFIG. 11for a received power pattern that matches the received power pattern of “medium, medium, medium, and high” to determine that the rail state is “Rail5crack”.

In this manner, a received power pattern specific to each rail state is obtained, and hence the received power pattern for each rail state is stored in the determination table ofFIG. 11. The analyzing unit501searches the determination table ofFIG. 11for a matched received power pattern, to thereby determine the current rail state and generate rail state information. The analyzing unit501transmits the rail state information to the information transmitting unit601. The information transmitting unit601transmits the rail state information received from the analyzing unit501to the ground apparatus located in the outside. The ground apparatus is located on the ground in the outside of the vehicle2.

Each of the above-mentioned functions of the rail state monitoring apparatus according to the first embodiment is implemented by a processing circuit. The processing circuit configured to implement each of the functions may be specific hardware, or may be a processor configured to execute a program stored in a memory.FIG. 12is a configuration diagram for illustrating a case in which each of the functions of the rail state monitoring apparatus1according to the first embodiment is implemented by a processing circuit including a processor and a memory.

As illustrated inFIG. 12, the rail state monitoring apparatus1includes an antenna1001,1008, an analog circuit1002,1009, an analog-to-digital converter (ADC)1003, a digital-to-analog converter (DAC)1004, a central processing unit (CPU)1005, an interface (I/F)1006, and a wireless apparatus1007.

The CPU1005generates an electric signal, and outputs the electric signal to the analog circuit1002via the DAC1004. The analog circuit1002amplifies the electric signal, and outputs the electric signal to the antenna1001. The antenna1001transmits the electric signal. Meanwhile, the electric signal received by the antenna1008is output to the analog circuit1009. The analog circuit1009amplifies the electric signal while eliminating noise, and transmits the electric signal to the CPU1005via the ADC1003. The CPU1005measures the received power of the electric signal and determines the rail state. The CPU1005outputs a result of the determination to the wireless apparatus1007via the I/F1006. The wireless apparatus1007transmits the result of the determination to an external apparatus or a neighboring vehicle.

In this manner, the first transmission antenna101and the second transmission antenna102are each formed of the antenna1001. Similarly, the first reception antenna201and the second reception antenna202are each formed of the antenna1008. When the processing circuit is a processor, the functions of respective components, namely, the transmitting unit301, the receiving unit401, the analyzing unit501, and the information transmitting unit601are implemented by software, firmware, or a combination of software and firmware. The software and the firmware are described as programs, and are stored in the memory. The processor implements the functions of the respective components by reading the programs stored in the memory and executing the programs. That is, the rail state monitoring apparatus1includes a memory for storing programs to be executed by the processing circuit so that a transmission step, a reception step, an analysis step, and an information transmission step are executed as a result.

It is to be understood that those programs cause a computer to execute a procedure or a method for the respective components described above. In this case, the memory corresponds to, for example, a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable and programmable read only memory (EEPROM), or other such nonvolatile or volatile semiconductor memory. The memory also corresponds to a magnetic disk, a flexible disk, an optical disc, a Compact Disc, a MiniDisc, a DVD, or other such medium.

The functions of the respective components described above may be partially implemented by specific hardware and partially implemented by software or firmware.

In this manner, the processing circuit can implement the functions of the respective components described above by hardware, software, firmware, or a combination thereof.

FIG. 13is a flowchart for illustrating a flow of processing of the rail state monitoring apparatus1according to the first embodiment. The processing ofFIG. 13is repeatedly executed at a cycle period set in advance.

InFIG. 13, first, in Step S1, the transmitting unit301generates a first electric signal, and outputs the first electric signal to the first transmission antenna101. In addition, the transmitting unit301generates a second electric signal, and outputs the second electric signal to the second transmission antenna102.

In Step S2, the first transmission antenna101outputs the first electric signal to the rail5. Meanwhile, the second transmission antenna102outputs the second electric signal to the rail6.

In Step S3, the first reception antenna201and the second reception antenna202receive the first electric signal and the second electric signal.

In Step S4, the receiving unit401calculates the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201and the second reception antenna202, and outputs the received powers to the analyzing unit501.

In Step S5, the analyzing unit501subjects the received powers calculated by the receiving unit401to the determination using the threshold values, classifies the received powers into the three levels of “high”, “medium”, and “low”, and generates a received power pattern. The analyzing unit501searches the determination table shown inFIG. 11for a received power pattern that matches the generated received power pattern to determine the rail states of the rail5and the rail6, and outputs the rail states as the rail state information.

In Step S6, the information transmitting unit601transmits the rail state information output from the analyzing unit501to the ground apparatus disposed in the outside.

In Step S7, the analyzing unit501determines whether rail state monitoring processing for the rail5and the rail6has been finished. When the rail state monitoring processing has not been finished, the processing returns to Step S1, and when the rail state monitoring processing has been finished, the processing of the rail state monitoring apparatus1according to the first embodiment is brought to an end.

As described above, according to the first embodiment, the analyzing unit501analyzes two kinds of propagation waves, namely, a surface wave and a guided wave, to thereby be able to determine the rail state as at least one of four states, namely, “normal”, “broken”, “crack”, and “surface anomaly”.

As described above, in the related-art apparatus disclosed in Japanese Patent Application Laid-open No. 2002-294609, an electric signal is not propagated even when a contact failure occurs between the rail and the wheel, which leads to a problem that a rail breakage and a contact failure cannot be distinguished from each other, to thereby cause erroneous determination. In view of this, another related-art apparatus is configured to compare detection results obtained by respective rail state monitoring apparatus, which are mounted to different vehicles, in order to reduce a rate of erroneous detection due to the erroneous determination. However, even with this configuration, when there is a change of the state, for example, when the rail is broken after the passage of one of the vehicles, the detection results do not match each other between the vehicles, and hence accurate determination becomes difficult.

In contrast, with the rail state monitoring apparatus according to the first embodiment, it is possible to detect a rail breakage and a rail surface anomaly in distinction from each other. Therefore, it is possible to inhibit presence of a rail breakage from being erroneously determined. The rail state monitoring apparatus according to the first embodiment can also perform the determination with a higher degree of reliability through use of one apparatus configuration.

In the first embodiment, it is also possible to store the rail state information obtained by the analyzing unit501in the memory at each spot to detect changes over time of the rail state information. That is, it is possible to detect the presence or absence of deterioration in rail state based on the presence or absence of reduction in received power. Further, the detection of a starting point at which the deterioration of the rail has started enables the rail state to be monitored with high accuracy.

In addition, the electric characteristics of the rail vary depending on weather conditions, but in the first embodiment, by statistically processing the changes over time, it is possible to monitor the rail state with a high degree of reliability without being affected by, for example, the weather conditions.

Furthermore, in the first embodiment, the rail state monitoring apparatus1is constructed as an on-vehicle apparatus mounted to the vehicle2, and hence it is possible to suppress the cost of initial installation and maintenance management compared to a case in which the rail state monitoring apparatus1is constructed as a ground apparatus.

Second Embodiment

FIG. 14is a diagram for schematically illustrating a configuration of a rail state monitoring apparatus1A according to a second embodiment of the present invention. As illustrated inFIG. 14, in the rail state monitoring apparatus1A according to the second embodiment, the apparatus failure detecting unit701is added to the components of the rail state monitoring apparatus1according to the first embodiment illustrated inFIG. 2. In the second embodiment, the apparatus failure detecting unit701is disposed, and hence it is possible to provide a rail state monitoring apparatus with higher reliability. The other components and operations are the same as those in the first embodiment.

The apparatus failure detecting unit701receives the input of the first electric signal and the second electric signal from the transmitting unit301. The apparatus failure detecting unit701also receives the input of the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201and the second reception antenna202, from the receiving unit401. The apparatus failure detecting unit701subjects the received power of the first electric signal and the received power of the second electric signal to determination using threshold values. At this time, it suffices that the number of threshold values is one. In the following description, such one threshold value is referred to as “threshold value Th3”. In the following description, the received power pattern generated by the apparatus failure detecting unit701is referred to as “second received power pattern”. The second received power pattern includes the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201, and the received powers of the first electric signal and the second electric signal, which are received by the second reception antenna202.

When the received powers of the first electric signal received by the first reception antenna201and the second reception antenna202are both smaller than the threshold value Th3, the apparatus failure detecting unit701generates a second received power pattern of “low, high, low, and high”, and determines that a failure has occurred in the first transmission antenna101.

When the received powers of the second electric signal received by the first reception antenna201and the second reception antenna202are both smaller than the threshold value Th3, the apparatus failure detecting unit701generates a second received power pattern of “high, low, high, and low”, and determines that a failure has occurred in the second transmission antenna102.

When the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201, are both smaller than the threshold value Th3, the apparatus failure detecting unit701generates a second received power pattern of “low, low, high, and high”, and determines that a failure has occurred in the first reception antenna201.

When the received powers of the second electric signal and the second electric signal, which are received by the second reception antenna202, are both smaller than the threshold value Th3, the apparatus failure detecting unit701generates a second received power pattern of “high, high, low, and low”, and determines that a failure has occurred in the second reception antenna202.

In this manner, an anomaly in the apparatus can be detected by the apparatus failure detecting unit701. Also in such a case, by combining the analysis result obtained by the apparatus failure detecting unit701and the analysis result obtained by the analyzing unit501with each other, it is possible to detect some kind of states of the rail5and the rail6even when a failure has occurred in the apparatus.

With reference toFIG. 15, a description is given for a case where a failure has occurred in the first transmission antenna101.

When a failure has occurred in the first transmission antenna101, the first electric signal is not transmitted. Therefore, the first reception antenna201receives the second electric signal propagated as the second guided wave32, and outputs the second electric signal to the receiving unit401. Meanwhile, the second reception antenna202receives the second electric signal propagated as the second surface wave22and the second guided wave32, and outputs the second electric signal to the receiving unit401.

With this processing, the apparatus failure detecting unit701determines that a failure has occurred in the first transmission antenna101based on the received power of the electric signal from the receiving unit401.

A description is given for a case in which a rail breakage has occurred in addition to the failure in the first transmission antenna101at this time. In that case, the loop coil10is disconnected, and hence the guided wave31and the guided wave32are not propagated. This brings the first reception antenna201to a non-reception state. The second reception antenna202receives the second surface wave22when the rail5is broken, and is brought to a non-reception state when the rail6is broken.

Next, a description is given for a case in which a rail surface anomaly has occurred in the rail5in addition to the failure in the first transmission antenna101. In that case, an electrical contact failure occurs between the wheels3and the rail5when the wheel3passes the anomaly spot on the rail5. Therefore, the loop coil10is disconnected, and the guided wave31and the guided wave32are not propagated. This brings the first reception antenna201to a non-reception state. The second reception antenna202receives only the second surface wave22.

In this manner, even when a failure has occurred in the first transmission antenna101, the analyzing unit501can detect at least a rail breakage or a rail surface anomaly.

Therefore, when apparatus failure information for notifying that a failure has occurred in the first transmission antenna101is received from the apparatus failure detecting unit701, the analyzing unit501uses only the received power of the second electric signal to determine the rail state. In the same manner, when apparatus failure information for notifying that a failure has occurred in the second transmission antenna102is received from the apparatus failure detecting unit701, the analyzing unit501uses only the received power of the first electric signal to determine the rail state.

Next, with reference toFIG. 16, a description is given for an electric signal to be received by each of the first reception antenna201and the second reception antenna202when a failure has occurred in the first reception antenna201.

Even when the first surface wave21, the first guided wave31, and the second guided wave32are propagated to the first reception antenna201, the first reception antenna201fails to receive the first surface wave21, the first guided wave31, and the second guided wave32due to the failure, and outputs the non-reception state.

The second reception antenna202receives the first guided wave31, the second surface wave22, and the second guided wave32, and outputs the first electric signal and the second electric signal.

With this processing, the apparatus failure detecting unit701determines that a failure has occurred in the first transmission antenna201based on the received power of the electric signal from the receiving unit401.

A description is given for a case in which a rail breakage has occurred in addition to the failure in the first transmission antenna201at this time.

When the rail5is broken, the second reception antenna202receives the second surface wave22. When the rail6is broken, the second reception antenna202is brought to a non-reception state.

A description is also given for a case in which a rail surface anomaly has occurred in addition to the failure in the first reception antenna201.

When a rail surface anomaly has occurred, the guided wave31and the guided wave32are not propagated. Therefore, the second reception antenna202receives the second surface wave22.

In this manner, even when a failure has occurred in the first reception antenna201, the analyzing unit501can detect at least a rail breakage or a rail surface anomaly.

Therefore, when apparatus failure information notifying that a failure has occurred in the first reception antenna201is received from the apparatus failure detecting unit701, the analyzing unit501uses only the received powers of the first electric signal and the second electric signal, which are received by the second reception antenna202, to determine the rail state. In the same manner, when apparatus failure information notifying that a failure has occurred in the second reception antenna202is received from the apparatus failure detecting unit701, the analyzing unit501uses only the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201, to determine the rail state.

Next, with reference toFIG. 18, a description is given for a determination method of distinguishing among a case of an apparatus failure in which a failure has occurred in a transmission antenna or a reception antenna, a case in which a rail breakage has occurred, and a case in which a rail surface anomaly has occurred from one another. InFIG. 18, the horizontal axis represents a train position, and the vertical axis represents a received power. InFIG. 18, a solid line50is a graph of a received power exhibited in the case of a rail breakage, a solid line51is a graph of a received power exhibited in the case of an apparatus failure, and a solid line52is a graph of a received power exhibited in the case of a rail surface anomaly. A distance between the first transmission antenna101and the first reception antenna201is represented as L1, and a distance between the front wheel3and the rear wheel4is represented as L2.

InFIG. 18, as indicated by the solid line50, a drop of the received power due to a rail breakage has a distance equal to or shorter than the distance L1. Meanwhile, as indicated by the solid line51, a drop of the received power due to an apparatus failure has a distance longer than the distance L1. In the case of the rail surface anomaly, the signal drops in power when the wheel3or4is brought into contact with the anomaly spot, and hence, as indicated by the solid line52, the drop of the signal power appears twice with an interval of the distance L2.

Therefore, in order to increase accuracy in determination, the analyzing unit501may obtain the running distance in which the received power drops based on data of the received power from the receiving unit401, and may determine the rail state based on the received power pattern and the running distance. In that case, a determination table shown inFIG. 19is used. In the determination table, the received power pattern and a condition for the running distance are stored for each rail state. The analyzing unit501generates a received power pattern based on the received power calculated by the receiving unit401, and calculates the running distance in which the received power drops. Then, the analyzing unit501searches the determination table ofFIG. 19for a received power pattern that matches the generated received power pattern, and when there is a match, determines whether the calculated running distance satisfies the condition for the running distance in the determination table ofFIG. 19. By thus determining the rail state through use of information on the running distance in which the received power drops and the received powers of the first electric signal and the second electric signal, it is possible to determine the states of the rail5and the rail6with higher accuracy.

Next, with reference toFIG. 20, a description is given for an electric signal to be received by each of the first reception antenna201and the second reception antenna202when an anomaly occurs in the wheel3or the wheel4.

When an anomaly occurs in the wheel3or the wheel4, the loop coil10is disconnected or the impedance of the loop coil10is changed, and hence the propagation states of the guided waves31and32are changed. The first reception antenna201receives the first surface wave21, and outputs the first electric signal to the receiving unit401. The second reception antenna202receives the second surface wave22, and outputs the second electric signal to the receiving unit401. Therefore, the received power pattern generated by the analyzing unit501becomes “high, low, low, and high”. This received power pattern is the same as in the case in which a surface anomaly has occurred in the rail5and the rail6. In view of this, a determination method of distinguishing between a case in which an anomaly has occurred in the wheel3or the wheel4and a case in which a rail surface anomaly has occurred is described below.

First, a description is given for a difference between the case in which an anomaly has occurred in the wheel3or the wheel4and the case in which a rail surface anomaly has occurred. In the case in which a rail surface anomaly has occurred, the loop coil10is disconnected only at a moment when the wheel passes the anomaly spot. The anomaly spot is passed by the front wheel3and the rear wheel4successively, and hence the loop coil10is disconnected twice with a time interval calculated based on the velocity of the train and the distance between the front and rear wheels. Therefore, the drop of the received power appears twice with the interval of the distance L2. Meanwhile, when an anomaly occurs in the wheel3or the wheel4, the loop coil10is disconnected at all times, and hence the running distance in which the received power drops becomes longer than the distance L1. Therefore, the analyzing unit501searches the determination table ofFIG. 19for a received power pattern that matches the generated received power pattern, and when there is a match, determines whether the calculated running distance satisfies the condition for the running distance in the determination table ofFIG. 19. This allows the analyzing unit501to correctly determine the case in which an anomaly has occurred in the wheel3or the wheel4and the case in which a rail surface anomaly has occurred in distinction from each other.

In consideration of the above description, because the analyzing unit501and the apparatus failure detecting unit701are configured to perform the determination through use of the information on the running distance in which the received power drops and on the received powers of the first electric signal and the second electric signal based on the determination table shown inFIG. 19, it is possible to determine the states of the rail5, the rail6, and the apparatus with higher accuracy. In the determination table ofFIG. 19, all the received power patterns are different from one another without an overlap between any pair of conditions, and hence it is possible to identify the rail state as at least one state.

As described above, according to the second embodiment, in the same manner as in the first embodiment, the analyzing unit501analyzes two kinds of propagation waves, namely, the surface waves21and22and the guided waves31and32, to thereby be able to determine the rail state as one of “good”, “rail broken”, “rail crack”, and “rail surface anomaly”. In addition, in the second embodiment, the apparatus failure detecting unit701is included, and hence it is possible to simultaneously determine a failure in the rail state monitoring apparatus1A.

Therefore, according to the second embodiment, an apparatus failure in the rail state monitoring apparatus1A and an anomaly in the rail state can be determined in distinction from each other. In this manner, according to the second embodiment, a failure in the rail state monitoring apparatus1A can be detected, and hence it is possible to achieve a fail-safe system.

Third Embodiment

The third embodiment of the present invention is described by taking a case in which the rail state monitoring apparatus1cooperates with a ground apparatus40. In this case, the description is given by taking a method for safe train operation management performed when an anomalous state has occurred in the rail.

As illustrated inFIG. 21, the ground apparatus40includes an information transmitting unit801and an operation management unit901. A configuration of the rail state monitoring apparatus1is the same as that of the rail state monitoring apparatus1described in the first embodiment, and hence a description thereof is omitted below.

In the rail state monitoring apparatus1, the information transmitting unit601transmits the rail state information received from the analyzing unit501to the ground apparatus40. The rail state information includes a vehicle position of the vehicle2, the rail state determined by the analyzing unit501, and the received powers of the first electric signal and the second electric signal, which are received by each of the first reception antenna201and the second reception antenna202.

As a method of acquiring the vehicle position of the vehicle2, for example, a vehicle position measured based on a map and satellite positioning may be acquired, or a mileage position of the train managed by an already-existing train control apparatus may be acquired. In this case, the train control apparatus refers to an apparatus configured to control the operations of all trains.

When receiving the rail state information from the rail state monitoring apparatus1, the information transmitting unit801of the ground apparatus40outputs the rail state information to the operation management unit901.

The operation management unit901reads the rail state information input from the information transmitting unit801. As a result, when the rail state information includes information on “rail broken”, “rail crack”, or other such anomaly, the operation management unit901transmits the information on the anomaly to another train via the information transmitting unit801. In addition, the operation management unit901generates an instruction signal for causing other trains to stop traveling or to slow down as required, and transmits the instruction signal to other trains via the information transmitting unit801.

The third embodiment is effective particularly in a moving block system. That is, when a rail is broken, an operation to which the concept of a fixed block system is virtually applied is performed, to thereby be able to improve safety. The moving block system refers to a block system for controlling a train interval in consideration of a distance from a preceding vehicle and the speeds of both trains. In contrast, the fixed block system refers to a block system in which a block section is fixed. In the fixed block system, the block section is set in a section between adjacent stations or a section between adjacent signals.

FIG. 22toFIG. 24are a specific example of a case in which the rail state monitoring apparatus1has detected a rail breakage at a middle point between a station and the next station. As illustrated inFIG. 24, the rail is divided into a plurality of sections to form a plurality of blocks. In the example ofFIG. 24, five blocks, namely, blocks B1001, B1002, B1003, B1004, and B1005are formed. A train control apparatus (not shown) and the ground apparatus40each hold block information on those blocks in the memory. The train control apparatus refers to an apparatus configured to control the operations of all trains.

As illustrated inFIG. 22andFIG. 23, first, in Step S11, the rail state monitoring apparatus1mounted to the vehicle2detects a rail breakage.

Subsequently, in Step S12, the rail state monitoring apparatus1notifies the ground apparatus40of information on a rail broken position as the rail state information.

Subsequently, in Step S13, the ground apparatus40receives the information on the rail broken position via a wireless apparatus41. The ground apparatus40identifies the block including the rail broken position, and sets the block as an entry prohibited section.

Subsequently, in Step S14, the ground apparatus40transmits information on the block set as the entry prohibited section to all the trains via the wireless apparatus41to inhibit each train to pass through the block set as the entry prohibited section.

FIG. 25toFIG. 27are a specific example of a case in which a rail breakage has been detected in station premises. As described above with reference toFIG. 24, the rail is divided into a plurality of sections to form a plurality of blocks. In the example ofFIG. 24, five blocks, namely, the blocks B1001, B1002, B1003, B1004, and B1005are formed. The train control apparatus and the ground apparatus40each hold the block information and virtual track information in the memory.

At this time, first, in Step S21, as illustrated inFIG. 27, virtual track circuits are assigned to the blocks B1001, B1002, B1003, B1004, and B1005, and on-rail information is converted into the virtual track circuit. The virtual track circuit serves as a track circuit utilized in related-art train operation management. As a method of assigning the virtual track circuit, one virtual track circuit may be assigned to one block, or one virtual track circuit may be assigned to a plurality of blocks.

Subsequently, in Step S22, the ground apparatus40transfers information on the virtual track circuit to an electronic interlocking apparatus42. With this as a trigger, the electronic interlocking apparatus42starts an operation in the virtual track circuit. The electronic interlocking apparatus42is an apparatus configured to drive and control signal equipment.

Subsequently, in Step S23, the rail state monitoring apparatus1mounted to the vehicle2detects a rail breakage.

Subsequently, in Step S24, the rail state monitoring apparatus1notifies the ground apparatus40of information on a rail broken position as the rail state information.

Subsequently, in Step S25, the ground apparatus40receives the information on the rail broken position via the wireless apparatus41. The ground apparatus40identifies the block including the rail broken position, and stops the virtual track circuit corresponding to the block.

Subsequently, in Step S26, the electronic interlocking apparatus42locks the signal equipment relating to the virtual track circuit due to the stoppage of the virtual track circuit.

As described above, according to the third embodiment, the rail state monitoring apparatus1is configured to cooperate with the ground apparatus40, and hence it is possible to maintain safe train operations by sharing information among trains traveling along the same service line.

The above description of the third embodiment is given by taking the case where the rail state monitoring apparatus1according to the first embodiment and the ground apparatus40cooperate with each other, but the rail state monitoring apparatus1A according to the second embodiment and the ground apparatus40may cooperate with each other. Also in that case, the same effects can be produced.

The above description is given by taking the case where the rail state monitoring apparatus1according to the first embodiment cooperates with the ground apparatus40, but the present invention is not limited thereto, and the rail state monitoring apparatus1A according to the second embodiment may cooperate with the ground apparatus40.

Fourth Embodiment

FIG. 28is a diagram for illustrating a rail state monitoring apparatus1and a ground apparatus40A in a fourth embodiment of the present invention.

In the fourth embodiment, in the same manner as in the third embodiment, a description is given for a case in which the rail state monitoring apparatus1cooperates with the ground apparatus40A. A configuration of the rail state monitoring apparatus1according to the fourth embodiment is the same as that of the rail state monitoring apparatus1described in the first embodiment, and hence a description thereof is omitted below.

As illustrated inFIG. 28, the ground apparatus40A includes the information transmitting unit801, the operation management unit901, and an analyzing unit1101. The operations of the information transmitting unit801and the operation management unit901are basically the same as those of the third embodiment. The following description is given for the operation of the ground apparatus40A mainly in terms of differences from that of the ground apparatus40according to the third embodiment.

The analyzing unit1101accumulates the rail state information received from the rail state monitoring apparatus1mounted to each vehicle2and the monitoring position calculated from the train position of the vehicle2in the memory together. The analyzing unit1101statistically processes a plurality of pieces of rail state information, and collectively manages the rail state of the entire rail. This allows the rail state to be monitored with a higher degree of reliability.

Now, a description is given for an operation of the rail state monitoring apparatus1according to the fourth embodiment.

The information transmitting unit601of the rail state monitoring apparatus1transmits the rail state information including the train position, the rail state, and the received powers and phases of the first electric signal and the second electric signal, which are received by the first reception antenna and the second reception antenna, to the ground apparatus40A.

The information transmitting unit601of the ground apparatus40A outputs the rail state information to the operation management unit901and the analyzing unit1101.

The analyzing unit1101stores the received powers and the phases of the surface waves21and22and the received powers and the phases of the guided waves31and32for each train position, and analyzes time-series data on the received powers and the phases of the surface waves21and22and time-series data on the received powers and the phases of the guided waves31and32at each train position.

FIG. 29is a graph for showing the time-series data on the received power of a surface wave or a guided wave at a given spot. InFIG. 29, the horizontal axis represents a time, and the vertical axis represents a received signal power.

When a crack has occurred in the rail5or6, the propagation state of the surface wave21or22is changed, for example, the surface wave21or22is reradiated at a crack spot. Therefore, the received power of the surface wave21or22drops due to the occurrence of a crack. The analyzing unit1101monitors the received power of the surface wave21or22at the same spot, and subjects the received power to the determination using the threshold values Th1 and Th2, to thereby detect a cracked state.

In addition, when a crack has occurred in the rail5or6, the impedance of the loop coil10is changed, and hence the received power and the phase of the guided wave31or32is changed. Therefore, as shown inFIG. 29, the time-series data on the received power is monitored, and changes of the received power and the phase of the guided wave due to a crack are detected, to thereby detect a cracked state. Not only a crack but also a rail surface anomaly including corrosion due to rust which causes an increase in rail resistance value can be detected in the same manner.

The analyzing unit1101outputs the determination result as to whether the rail state is “good” or “crack” to the operation management unit901as second rail state information.

When the second rail state information includes information indicating that the rail state is “crack”, the operation management unit901outputs rail crack information and instruction information for instructing a train to slow down to the information transmitting unit801.

The information transmitting unit801transmits the instruction information to another train.

As described above, according to the fourth embodiment, the analyzing unit1101of the ground apparatus40A analyzes variations with time of the propagation states of the surface waves21and22and the guided waves31and32at each spot, to thereby be able to detect the crack state exhibited before the rail is broken. In this manner, according to the fourth embodiment, a crack spot can be detected before a rail is broken, and hence it is possible to maintain safer train operations.

The above description is given by taking the case where the rail state monitoring apparatus1according to the first embodiment cooperates with the ground apparatus40A, but the present invention is not limited thereto, and the rail state monitoring apparatus1A according to the second embodiment may cooperate with the ground apparatus40A.

Fifth Embodiment

In a fifth embodiment of the present invention, a description is given for another mode of the transmission antenna and the reception antenna.

In the fifth embodiment, as illustrated inFIG. 30, the second transmission antenna102illustrated inFIG. 1is removed. Therefore, as illustrated inFIG. 30, a rail state monitoring apparatus1B according to the fifth embodiment includes the first transmission antenna101, the first reception antenna201, and the second reception antenna202. Although not shown inFIG. 30, the rail state monitoring apparatus1B also includes the transmitting unit301, the receiving unit401, the analyzing unit501, and the information transmitting unit601, which are illustrated inFIG. 1.

The first reception antenna201receives the first electric signal propagated as the first surface wave21and the first guided wave31, and transmits the first electric signal to the receiving unit401.

The second reception antenna202receives the first electric signal propagated as the first surface wave31, and transmits the first electric signal to the receiving unit401.

The receiving unit401calculates the received powers of the first electric signal, which are received by the first reception antenna201and the second reception antenna202.

The analyzing unit501uses a determination table shown inFIG. 31based on the received power calculated by the receiving unit401to determine the rail states of the rail5and the rail6.

The rail state monitoring apparatus1B may include the apparatus failure detecting unit701described in the second embodiment. In that case, the apparatus failure detecting unit701uses the determination table shown inFIG. 31based on the received power calculated by the receiving unit401to determine the presence or absence of a failure in the first transmission antenna101, the first reception antenna201, the second reception antenna202, and the wheels3and4.

In this manner, even with the configuration illustrated inFIG. 30, it is possible to determine the states of the rails5and6from among “good”, “rail broken”, “rail surface anomaly”, and “rail crack”.

The above description is given by taking the case where the number of transmission antennas is one, but the number of reception antennas may be one instead. That is, the rail state monitoring apparatus1B includes the first transmission antenna101, the second transmission antenna102, and the first reception antenna201.

In that case, the first reception antenna201receives the first electric signal propagated as the first surface wave21and the first guided wave31, and transmits the first electric signal to the receiving unit401. Meanwhile, the first reception antenna201receives the second electric signal propagated as the second surface wave22and the second guided wave32, and transmits the second electric signal to the receiving unit401.

The receiving unit401calculates the received powers of the first electric signal and the second electric signal, which are received by the first reception antenna201.

The analyzing unit501uses a determination table shown inFIG. 31orFIG. 33based on the received power calculated by the receiving unit401to determine the rail states of the rail5and the rail6.

The rail state monitoring apparatus1B may include, also in this case, the apparatus failure detecting unit701described in the second embodiment. In that case, the apparatus failure detecting unit701uses the determination table shown inFIG. 31orFIG. 33based on the received power calculated by the receiving unit401to determine the presence or absence of a failure in the first transmission antenna101, the second transmission antenna102, the first reception antenna201, and the wheels3and4.

As described above, according to the fifth embodiment, even when the number of transmission antennas is one or the number of reception antennas is one, the analyzing unit501can determine the rail states of the rails5and6from among “good”, “rail broken”, “rail surface anomaly”, and “rail crack” through use of the determination table shown inFIG. 31orFIG. 33.

The present invention has been described with reference to the specific preferred embodiments, but it is to be understood that various other adaptations and changes can be made within the spirit and scope of the present invention. Therefore, it is an object of the appended claims to cover all such modifications and changes that fall within the true spirit and scope of the present invention.