FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
RAIL BREAKAGE DETECTION DEVICE AND RAIL BREAKAGE RESULT
MANAGEMENT SYSTEM;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI
2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED

DESCRIPTION
Technical Field
[0001] The present disclosure relates to a rail breakage detection device which detects
breakage of railroad rails and a rail breakage result management system which 5 uses the rail
breakage detection device.
Background Technology
[0002] Conventionally, the railroad rail breakage detection is made possible by a track circuit
10 for train position detection. In recent years, introduction of a wireless train control system
(communication-based train control: CBTC) which does not use the track circuit for train
position detection is in progress; and thus, a rail breakage detection method which does not
use the track circuit is required. One of the rail breakage detection methods which do not
use the track circuit is a breakage detection method utilizing return current.
[0003] Current supplied from a substation to a rail car through an overhead line during the
train travel is consumed by the rail car and then returns to the substation via the rails. The
current returning to the substation through the rails is called return current. The return
currents flow through a pair of rails in the same direction, meets at an electrical neutral
point of an impedance bond installed at each of block sections of the rails, and then branches
again and flows into the block section of adjacent rails. If there is no abnormality such as
rail breakage, the return currents flowing from the rail car to the pair of rails show balanced
values. However, if one of the pair of rails is broken, the return current leaks into the
ground at the broken rail side, so imbalance occurs in the return currents flowing through
the pair of rails.
[0004] Patent Document 1 discloses a rail breakage detection method, a rail breakage
detection device, and a rail breakage point detection method using the device, and describes a
technology in which the return currents are measured on the rail car; the imbalance ratio of
the return currents flowing through the pair of rails is calculated; and thus the breakage of
the rails is detected.
[0005] In a rail breakage detection device disclosed in Patent Document 2, it is described that
a first detection section L1 is set in one of the pair of rails and a second detection section L2 is
set in the other, and that rail breakage is detected from the imbalance occurring between a
first voltage drop signal V1 generated in the first detection section L1 by the return current
and a second voltage drop signal V2 generated in the second detection section by the return
current.
Prior Art Documents
Patent Documents
[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No.
HEI 6-321110
Patent Document 2: Japanese Unexamined Patent Application Publication No.
2012-91671
Summary of Invention
Problems to be Solved 5 by Invention
[0007] In the rail breakage detection method, the rail breakage detection device, and the rail
breakage point detection method using the device that are described in Patent Document 1,
the return current is measured on the rail car based on a principle equivalent to that of the
rail breakage detection method used in an automatic train control (ATC), etc. However, since
the return current is a direct current or a low-frequency current, it is difficult to measure the
return current accurately on the rail car. Also, since the resistance component of the rail is
extremely small, it is necessary to lengthen the detection section in order to detect breakage
of rails accurately using the rail breakage detection device described in Patent Document 2.
However, if the detection section is made long, the configuration becomes complicated
because it is necessary to lay down long conducting wires along the rails.
[0008] The present disclosure is made in order to solve the above problems and an object is to
obtain a rail breakage detection device which can detect breakage of rails and a rail breakage
result management system using the rail breakage detection device with a simple
configuration.
Means for Solving the Problems
[0009] A rail breakage detection device according to the present disclosure comprises:
an electromotive force generating unit including
a first core part that is provided annularly along a circumferential direction of a first cable
electrically connecting an electrical neutral point of an impedance bond to a prescribed block
section of a first rail, the impedance bond electrically connecting the first rail and a second
rail in a pair,
a second core part that is provided annularly along a circumferential direction of a second
cable electrically connecting the electrical neutral point of the impedance bond to the
prescribed block section of the second rail,
a first coil that is wound around the first core part to generate a first electromotive force in
accordance with a current variation occurring in the first cable, and
a second coil that is connected electrically to the first coil, is wound around the second core
part to generate a second electromotive force in accordance with a current variation occurring
in the second cable, and generates the second electromotive force so as to cancel the first
electromotive force out when the current variation occurring in the second cable is identical
with the current variation occurring in the first cable in terms of a direction and a
magnitude,
40 the electromotive force generating unit generating an electromotive force being a sum of
the first electromotive force and the second electromotive force; and
a breakage determination unit to determine that the first rail or the second rail is broken
based on the electromotive force generated by the electromotive force generating unit.
[0010] A rail breakage detection device according to the present disclosure comprises:
an electromotive force generating unit including
a first core part that is provided annularly along a circumferential direction of a first cable
electrically connecting an electrical neutral point of an impedance bond to a prescribed block
section of the first rail, and made of a magnetic material to generate a first 5 magnetic flux in
accordance with return current flowing through the first cable, the impedance bond
electrically connecting a first rail and a second rail in a pair,
a second core part that is provided annularly along a circumferential direction of a second
cable electrically connecting the electrical neutral point of the impedance bond to the
prescribed block section of the second rail, is mechanically connected to the first core part,
generates a second magnetic flux in accordance with return current flowing through the
second cable, and is made of a magnetic material to generate the second magnetic flux so as
to cancel the first magnetic flux out when the return current flowing through the second
cable is identical with the return current flowing through the first cable in terms of a
direction and a magnitude, and
a Hall element that is disposed in a gap provided in either the first core part or the second
core part to generate an electromotive force in accordance with a sum of the first magnetic
flux and the second magnetic flux; and
a breakage determination unit to determine that the first rail or the second rail is broken
based on the electromotive force generated by the Hall element of the electromotive force
generating unit.
[0011] A rail breakage result management system according to the present disclosure
includes:
the rail breakage detection device described above; and
a management server to store a breakage detection result of rails detected by the rail
breakage detection device and a management number in association with each other, the
management number being assigned individually to a block section of rails, wherein
the rail breakage detection device includes an information output unit to output the
breakage detection result of the rails and the management number to the management
server via a network.
Effects of Invention
[0012] The rail breakage detection device according to the present disclosure makes it
35 possible to detect breakage of rails with a simple configuration.
[0013] The rail breakage result management system according to the present disclosure
makes it possible to detect breakage of rails with a simple configuration.

Brief Description of Drawings
[0014] FIG. 1 is a diagram showing a configuration around a rail breakage detection device
according to Embodiment 1 of the present disclosure.
FIG. 2 is a diagram showing an example of a configuration of an impedance bond attached to
the rails.
FIG. 3 is a diagram showing an example of a configuration of the rail breakage detection
device according to Embodiment 1 of the present disclosure.
FIG. 4 is a diagram showing a variation of an electromotive force generating unit of the rail
breakage detection device according to Embodiment 1 of the present disclosure.
FIG. 5 is a diagram showing an example of a positional relationship of the first 5 cable and the
second cable with the first core part and the second core part of the rail breakage detection
device according to Embodiment 1 of the present disclosure.
FIG. 6 is a diagram showing an example of a configuration of a breakage determination unit
of the rail breakage detection device according to Embodiment 1 of the present disclosure.
FIG. 7 is a diagram showing how return current flows when the rails are not broken.
FIG. 8 is a diagram showing how the return current flows when a rail is broken.
FIG. 9 is a diagram showing an example of a configuration of a rail breakage detection
device according to Embodiment 2 of the present disclosure.
FIG. 10 is a diagram showing a variation of an electromotive force generating unit of the rail
breakage detection device according to Embodiment 2 of the present disclosure.
FIG. 11 is a diagram showing an example of a configuration of a rail breakage result
management system according to Embodiment 3 of the present disclosure.
FIG. 12 is a diagram showing an example of a configuration of a management server of the
rail breakage result management system according to Embodiment 3 of the present
disclosure.
FIG. 13 is a diagram showing an example of a configuration of the rail breakage result
management system according to Embodiment 3 of the present disclosure.
Embodiments for Carrying Out the Invention
[0015] Hereinafter, referring to the attached drawings, embodiments of the rail breakage
detection device disclosed in the present application will be described in detail. Note that
the following embodiments are just examples, and the present disclosure is not limited by
these embodiments.
[0016] Embodiment 1
FIG. 1 is a diagram showing a configuration of a rail breakage detection device 100 and its
surroundings according to Embodiment 1 of the present disclosure. FIG. 1 shows a train 1,
a first rail 2a and a second rail 2b that are a pair, rail insulating members 3a and 3b
respectively provided on the first rail 2a and the second rail 2b, an impedance bond 4 that
electrically connects the first rail 2a and the second rail 2b, a rail breakage detection device
100 attached to the impedance bond 4 for detecting breakage of the first rail 2a or the second
rail 2b, a substation 5, and an overhead line 6. The impedance bond 4 is installed at a
location where the first rail 2a and the second rail 2b are insulated from an adjacent block
section by the rail insulating members 3a and 3b, and is a device which allows only return
current to flow into the adjacent block section without passing signal current used for train
control.
[0017] FIG. 2 is a diagram showing a configuration of the impedance bond 4 electrically
connecting the first rail 2a and the second rail 2b. A first winding 42a of the impedance
bond 4 is connected to the first rail 2a by a first cable 41a and to the second rail 2b by a
second cable 41b. The first rail 2a to which the first cable 41a is connected and the second
rail 2b to which the second cable 41b is connected are a pair of rails in the same block section.
A second winding 42b is connected to the first rail 2a by a third cable 43a and to the second
rail 2b by a fourth cable 43b. The first rail 2a to which the third cable 43a 5 is connected and
the second rail 2b to which the fourth cable 43b is connected are a pair of rails in the same
block section. The first winding 42a and the second winding 42b are electrically connected
by a fifth cable 44.
The fifth cable 44 has an electrical neutral point P.
[0018] FIG. 3 is a diagram showing an example of a configuration of the rail breakage
detection device 100 which detects breakage of the first rail 2a or the second rail 2b. As
shown in FIG. 3, the rail breakage detection device 100 includes an electromotive force
generating unit 11 which generates an electromotive force in accordance with the current
variations caused by the return currents in the first cable 41a and the second cable 41b, and a
breakage determination unit 12 which performs breakage determination of the first rail 2a to
which the first cable 41a is connected or the second rail 2b to which the second cable 41b is
connected, on the basis of the electromotive force generated by the electromotive force
generating unit 11.
[0019] In FIG. 3, an example of a configuration in which the electromotive force generating
unit 11 is attached to the first cable 41a and the second cable 41b is shown. However, rail
breakage can be detected even with a configuration in which the electromotive force
generating unit 11 is attached to the third cable 43a and the fourth cable 43b. When the
electromotive force generating unit 11 is attached to the third cable 43a and the fourth cable
43b, the electromotive force generating unit 11 generates the electromotive force in
accordance with the current variations occurring in the third cable 43a and the fourth cable
43b. The breakage determination unit 12 determines whether breakage has occurred in the
first rail 2a to which the third cable 43a is connected or the second rail 2b to which the fourth
cable 43b is connected, on the basis of the electromotive force generated by the electromotive
force generating unit 11.
[0020] Regarding in which block section the rail breakage detection device 100 is to be
installed to determine the breakage of the rail, it is decided before or at the time when the
rail breakage detection device 100 is installed. In the following description, a case where
the electromotive force generating unit 11 is attached to the first cable 41a and the second
cable 41b will be described.
[0021] The rail breakage detection device 100 according to Embodiment 1 is configured to
perform breakage determination by using the breakage determination unit 12 to detect
breakage of the first rail 2a or the second rail 2b when an electromotive force is generated in
the electromotive force generating unit 11. A detailed configuration of the rail breakage
detection device 100 will be described later.
[0022] Typically, the return currents flowing through the first rail 2a and the second rail 2b
show different values every time. Therefore, when measuring the return currents and
detecting breakage of the first rail 2a or the second rail 2b, it is necessary to measure the
current values of the return currents every time they flow and to detect breakage using a
threshold in accordance with the current 5 values measured.
[0023] In contrast, in the rail breakage detection device 100 according to Embodiment 1, the
electromotive force generating unit 11 is configured not to generate the electromotive force
when current variations of the same magnitude and direction occur in the first cable 41a and
the second cable 41b by the return currents. In other words, the configuration is such that
the electromotive force generating unit 11 generates the electromotive force in a case where
imbalance occurs in the current variations of the first cable 41a and the second cable 41b
caused by imbalance that occurs in the return currents flowing through the first rail 2a and
the second rail 2b when the first rail 2a or the second rail 2b is broken.
[0024] Therefore, regardless of the magnitude of the return current, the rail breakage
detection device 100 according to Embodiment 1 can detect breakage of the first rail 2a or the
second rail 2b when the electromotive force generating unit 11 generates the electromotive
force. Further, since it is not necessary to measure the current values of the return current,
the rail breakage detection device 100 according to Embodiment 1 can detect rail breakage
with a simple configuration.
[0025] Next, detailed configurations of the electromotive force generating unit 11 and the
breakage determination unit 12 of the rail breakage detection device 100 will be described.
[0026] The electromotive force generating unit 11 includes a first core part 111a annularly
provided in the circumferential direction of the first cable 41a, a second core part 111b
annularly provided in the circumferential direction of the second cable 41b, a first coil 112a
which is wound around the first core part 111a and generates a first electromotive force in
accordance with the current variation that occurs in the first cable 41a, and a second coil
112b which is wound around the second core part 111b and generates a second electromotive
force in accordance with the current variation that occurs in the second cable 41b. The
shapes of the first core part 111a and the second core part 111b is not limited to an annular
shape and, for example, may be a polygonal shape such as a triangular shape or a square
shape, or an oval shape.
[0027] The first core part 111a and the second core part 111b are made of a magnetic material.
By the first core part 111a and the second core part 111b made of a magnetic material, a
magnetic flux generated in accordance with the current variation that occurs in the first
cable 41a can be prevented from leaking outside the first core part 111a, and a magnetic flux
generated in accordance with the current variation that occurs in the second cable 41b can be
prevented from leaking outside the second core part 111b. Therefore, the positions where
the first coil 112a and the second coil 112b are provided can be changed accordingly, and as a
result, the configuration of the rail breakage detection device 100 can be simplified.
[0028] Note that the first core part 111a and the second core part 111b are not necessarily
made of a magnetic material, and for example, they may be made of a non-magnetic material
such as plastic. However, when the first core part 111a and the second core part 111b are
made of a non-magnetic material, it is necessary to place the first coil 5 112a at a position
where the first coil 112a does not generate an electromotive force due to the current variation
that occurs in the second cable 41b, and to place the second coil 112b at a position where the
second coil 112b does not generate an electromotive force due to the current variation that
occurs in the first cable 41a.
[0029] 10 The first coil 112a and the second coil 112b are electrically connected. Also, the first
coil 112a and the second coil 112b are respectively wound around the first core part 111a and
the second core part 111b such that the first electromotive force generated by the first coil
112a and the second electromotive force generated by the second coil 112b cancel each other
out when current variations of the same magnitude and direction occur in the first cable 41a
and the second cable 41b. Here, the current variations in the same direction means a case
in which both the current flowing from the first rail 2a to the electrical neutral point P of the
impedance bond 4 via the first cable 41a and the current flowing from the second rail 2b to
the electrical neutral point P of the impedance bond 4 via the second cable 41b increase or
decrease, or a case in which both the current flowing from the electrical neutral point P of the
impedance bond 4 to the first rail 2a via the first cable 41a and the current flowing from the
electrical neutral point P of the impedance bond 4 to the second rail 2b via the second cable
41b increase or decrease. Further, the electromotive forces opposite to each other in the
direction means that the first electromotive force generated between both ends of the first coil
112a and the second electromotive force generated between both ends of the second coil 112b
are in the direction in which their forces are cancelled out with each other.
[0030] The electromotive forces generated in the first coil 112a and the second coil 112b are
represented by Equation (1). Note that in Equation (1) takes 1 or 2. To be specific, when
= 1, in Equation (1), V1 is the first electromotive force, N1 is the number of turns of the first
coil 112a, Φ1 is a magnetic flux density generated in the first core part 111a, μ1 is a magnetic
permeability of the first core part 111a, and H1 is a magnetic flux generated in the first core
part 111a. When = 2, in Equation (1), V2 is the second electromotive force, N2 is the
number of turns of the second coil 112b, Φ2 is a magnetic flux density generated in the second
core part 111b, μ2 is a magnetic permeability of the second core part 111b, and H2 is a
magnetic flux generated in the second core part 111b.
[0031]
[Equation 1]
[0032] In order to have a configuration in which the electromotive force generating unit 11
will not generate the electromotive force when the current variations of the same magnitude
and direction occur in the first cable 41a and the second cable 41b, V1 (the first electromotive
force) and V2 (the second electromotive force) need to be equal in magnitude 5 and opposite in
direction. That is, V1 = −V2 needs to be held. For example, if V1 (the first electromotive
force) and V2 (the second electromotive force) are equal in magnitude and opposite in
direction (V1 = −V2) and the first core part 111a and the second core part 111b are made of the
same material and the first coil 112a and the second coil 112b are made of the same material,
N1 = −N2 holds from Equation (1), so that the winding directions of the first coil 112a and the
second coil 112b are opposite to each other and the numbers of turns of the first coil 112a and
the second coil 112b are the same.
[0033] In other words, the material and shape of the first core part 111a, the material, shape,
and the number of turns of the first coil 112a, the material and shape of the second core part
111b, and the material, shape, and the number of turns of the second coil 112b need to be
configured such that Equation (1) satisfies V1 = −V2 when the current variations of the same
magnitude and direction occur in the first cable 41a and the second cable 41b.
[0034] The breakage determination unit 12 is connected electrically to the first coil 112a and
the second coil 112b and measures the electromotive force generated by the electromotive
force generating unit 11. When the electromotive force generated by the electromotive force
generating unit 11 is greater than or equal to a threshold, the breakage determination unit
12 performs breakage determination of the first rail 2a or the second rail 2b. The threshold
is determined, for example, by measuring in advance values of the electromotive force
generated by the electromotive force generating unit 11 when the train 1 travels with the
first rail 2a and the second rail 2b unbroken, and by calculating an average and a standard
deviation of the electromotive force. Specifically, the threshold is determined on the basis of
Equation (2). Here, Vh is a threshold value, V0 is an average of the electromotive force, σ is
a standard deviation thereof, and α is a value determined in accordance with the required
accuracy of the rail breakage detection.
Vh = V0 + ασ (2)
[0035] FIG. 4 shows a variation of the electromotive force generating unit 11. The first core
part 111a and the second core part 111b do not necessarily have a loop shape and may have a
structure having a gap C and a gap D, respectively, as shown in FIG. 4. By providing the
gap C and the gap D to the first core part 111a and the second core part 111b, respectively, it
becomes easy to attach the first core part 111a and the second core part 111b to the first cable
41a and the second cable 41b, respectively.
[0036] FIG. 5 is a diagram showing a positional relationship of the first cable 41a and the
second cable 41b with the first core part 111a and the second core part 111b. In FIG. 5, a
normal vector Na is the normal vector of the opening plane Sa formed inside the first core
part 111a, and a normal vector Nb is the normal vector of the opening plane Sb formed inside
the second core part 111b. As shown in FIG. 5, the first cable 41a is provided 5 in parallel
with the normal vector Na, and the second cable 41b is provided in parallel with the normal
vector Nb. That is, FIG. 5 shows that the direction of the normal vector Na and the direction
of the current flowing through the first cable 41a are parallel, and the direction of the normal
vector Nb and the direction of the current flowing through the second cable 41b are parallel.
[0037] The magnitude of the magnetic flux that is generated in each of the first core part 111a
and the second core part 111b by the currents respectively flowing through the first cable 41a
and the second cable 41b is determined according to Ampere's law. That is, when the
direction of the normal vector Na and the direction of the current flowing through the first
15 cable 41a are made parallel and the direction of the normal vector Nb and the direction of the
current flowing through the second cable 41b are made parallel, the magnetic flux generated
in each of the first core part 111a and the second core part 111b becomes the largest. As a
result, the electromotive forces generated by the electromotive force generating unit 11 in
accordance with the current variations occurring in the first cable 41a and the second cable
41b increase. Therefore, by providing the first cable 41a in parallel with the normal vector
Na and the second cable 41b in parallel with the normal vector Nb, it is possible to accurately
detect the current variations occurring in the first cable 41a and the second cable 41b.
[0038] FIG. 6 is a diagram showing a configuration of the breakage determination unit 12.
The breakage determination unit 12 can be implemented by software control by a CPU 1001a
executing a program stored in a memory 1002a, as shown in FIG. 6. Further, the breakage
determination unit 12 may be configured such that, when the first rail 2a or the second rail
2b is broken and the electromotive force generated by the electromotive force generating unit
11 is greater than or equal to a predetermined threshold, the generated electromotive force is
used as a power source for operation of the breakage determination unit 12. In a case where
a configuration is made such that the electromotive force generated by the electromotive force
generating unit 11 is used as the power source, the breakage determination unit 12 can
perform the breakage determination of the first rail 2a or the second rail 2b without using an
external power supply.
[0039] Next, how the return current flows will be described separately for a case where
neither the first rail 2a nor the second rail 2b is broken as compared to a case where the first
rail 2a or the second rail 2b is broken.
[0040] FIG. 7 is a diagram showing how the return current flows when neither the first rail
2a nor the second rail 2b is broken. In FIG. 7, the arrows indicate the direction in which the
return current flows, and A1, A2, and A3 each indicate the block section sectioned by the rail
insulating members 3a and 3b. In FIG. 7, the electromotive force generating unit 11 of the
rail breakage detection device 100 is provided for the first cable 41a and the second cable 41b
in each of the impedance bonds 4a, 4b, 4c, and 4d. However, the illustration is omitted in FIG.
[0041] If neither the first rail 2a nor the second rail 2b is broken, the return currents flowing
through the first rail 2a and the second rail 2b of the block section A1 pass 5 through the first
cable 41a and the second cable 41b of the impedance bond 4b, meet at the electrical neutral
point P of the impedance bond 4b, pass through the third cable 43a and the fourth cable 43b
of the impedance bond 4b, and flow into the first rail 2a and the second rail 2b of the adjacent
block section A2. The return current flows in the same manner when flowing from the block
10 section A2 to the block section A3.
[0042] As shown in Fig. 7, when neither the first rail 2a nor the second rail 2b is broken, the
magnitudes of the return currents flowing through the first rail 2a and the second rail 2b are
equal in each of the block sections, so that the current variations occurring in the first cable
41a and the second cable 41b in each of the block sections are balanced. Also, the current
variations occurring in the third cable 43a and the fourth cable 43b in each block section are
balanced.
[0043] Next, how the return current flows when the second rail 2b is broken will be described.
FIG. 8 is a diagram showing how the return current flows when a breakage B in the second
rail 2b occurs. In FIG. 8, the arrows indicate the direction in which the return current flows,
and A1, A2, and A3 each indicate the block section sectioned by the rail insulating members
3a and 3b. In FIG. 8, the electromotive force generating unit 11 of the rail breakage
detection device 100 is provided for the first cable 41a and the second cable 41b in each of the
impedance bonds 4a, 4b, 4c, and 4d. However, the illustration is omitted in FIG. 8.
[0044] Since no breakage occurs in the first rail 2a and the second rail 2b in the block section
A1, the current variations occurring in the first cable 41a and the second cable 41b of the
impedance bond 4b are balanced. Also, the current variations occurring in the third cable
43a and the fourth cable 43b of the impedance bond 4a are balanced.
[0045] However, in the block section A2, the breakage B occurs in the second rail 2b, so that
only leakage current based on a leakage impedance component between the second rail 2b
and the ground flows through the second rail 2b in the block section A2. Generally, in a
railroad, since the leakage impedance is set to be large, the return current flowing through
the second rail 2b of the block section A2 is small. Therefore, imbalance occurs in the return
currents flowing through the first rail 2a and the second rail 2b of the block section A2, so
that the current variations occurring in the first cable 41a and the second cable 41b of the
impedance bond 4c are imbalanced. In addition, with the breakage B occurring in the
second rail 2b of the block section A2, the current variations occurring in the third cable 43a
and the fourth cable 43b of the impedance bond 4b are also imbalanced.
[0046] Due to the breakage B, the return currents flowing through the first cable 41a and the
second cable 41b of the impedance bond 4c become imbalanced. Even so, the return currents
flowing through the first cable 41a and the second cable 41b of the impedance bond 4c meet at
the electrical neutral point P of the impedance bond 4c, pass through the third cable 43a and
the fourth cable 43b of the impedance bond 4c, and flow into the first rail 2a and the second
rail 2b of the adjacent block section A3. Since no breakage occurs in the first rail 2a and the
second rail 2b of the block section A3, the current variations occurring in the 5 third cable 43a
and the fourth cable 43b of the impedance bond 4c are balanced, and the return currents
flowing through the first rail 2a and the second rail 2b of the block section A3 are balanced.
[0047] Therefore, as shown in Fig. 8, even when the breakage B occurs in the block section A2,
the return currents flowing through the first rail 2a and the second rail 2b of the block
section A1 and block section A3 that are adjacent are balanced, and the current variations
occurring in the first cable 41a and the second cable 41b of each of the impedance bonds 4b
and 4d are balanced. Also, the current variations occurring in the third cable 43a and the
fourth cable 43b of the impedance bond 4c are balanced.
[0048] As described using FIG. 7, when neither the first rail 2a nor the second rail 2b is
broken, the return currents flowing through the first rail 2a and the second rail 2b are
balanced, so that the current variations occurring in the first cable 41a and the second cable
41b of the impedance bond 4 are also balanced. The electromotive force generating unit 11
is configured such that it does not generate the electromotive force when the current
variations of the same magnitude and direction occur in the first cable 41a and the second
cable 41b. Therefore, when neither the first rail 2a nor the second rail 2b is broken, the
electromotive force generating unit 11 does not generate the electromotive force.
[0049] On the other hand, as described using FIG. 8, when the first rail 2a or the second rail
2b is broken, imbalance occurs in the return currents flowing through the first rail 2a and the
second rail 2b in the block section where the breakage occurs, so that the current variations
occurring in the first cable 41a and the second cable 41b respectively connected to the first
rail 2a and the second rail 2b in the block section where the breakage occurs are imbalanced.
Since the electromotive force generating unit 11 generates the electromotive force in
accordance with the current variations occurring in the first cable 41a and the second cable
41b, the rail breakage detection device 100 can detect the rail breakage.
[0050] The rail breakage detection device 100 detects the rail breakage when the current
variations occurring in the first cable 41a and the second cable 41b are imbalanced. That is,
in the case shown in FIG. 8, the rail breakage detection device 100 can detect that rail
breakage occurs in the block section A2.
[0051] Further, when the first rail 2a or the second rail 2b is broken, the current variations
occurring in the third cable 43a and the fourth cable 43b respectively connected to the first
rail 2a and the second rail 2b in the block section where the rail breakage occurs are also
imbalanced. Therefore, even in a case where a configuration in which the electromotive
force generating unit 11 is attached to the third cable 43a and the fourth cable 43b is adopted,
the rail breakage detection device 100 can detect rail breakage in the first rail 2a and the
second rail 2b respectively connected to the third cable 43a and the fourth cable 43b when the
current variations occurring in the third cable 43a and the fourth cable 43b are imbalanced.
[0052] Note that, also even in a configuration in which the electromotive force generating
unit 11 is attached to the third cable 43a and the fourth cable 43b, the electromotive 5 force
generating unit 11 is configured not to generate the electromotive force when the current
variations of the same magnitude and direction occur in the third cable 43a and the fourth
cable 43b. Here, the current variations in the same direction means a case in which both the
current flowing from the electrical neutral point P of the impedance bond 4 to the first rail 2a
via the third cable 43a and the current flowing from the electrical neutral point P of the
impedance bond 4 to the second rail 2b via the fourth cable 43b increase or decrease, or a case
in which both the current flowing from the first rail 2a to the electrical neutral point P of the
impedance bond 4 via the third cable 43a and the current flowing from the second rail 2b to
the electrical neutral point P of the impedance bond 4 via the fourth cable 43b increase or
decrease.
[0053] The rail breakage detection device according to Embodiment 1 comprises:
the electromotive force generating unit including
the first core part that is provided annularly along the circumferential direction of the first
cable electrically connecting the electrical neutral point of the impedance bond to a prescribed
block section of the first rail, the impedance bond electrically connecting the first rail and the
second rail in a pair,
the second core part that is provided annularly along the circumferential direction of the second
cable electrically connecting the electrical neutral point of the impedance bond to a prescribed
block section of the second rail,
the first coil that is wound around the first core part to generate the first electromotive force in
accordance with a current variation occurring in the first cable, and
the second coil that is connected electrically to the first coil, is wound around the second core
part to generate the second electromotive force in accordance with a current variation occurring
in the second cable, and generates the second electromotive force so as to cancel the first
electromotive force out when the current variation occurring in the second cable is identical with
the current variation occurring in the first cable in terms a direction and a magnitude,
the electromotive force generating unit generating an electromotive force being a sum of the
first electromotive force and the second electromotive force; and
the breakage determination unit to determine that the first rail or the second rail is broken
based on the electromotive force generated by the electromotive force generating unit.
[0054] Further, the breakage determination unit of the rail breakage detection device
according to Embodiment 1 is characterized in that the rail breakage in the first rail or the
second rail is determined when the electromotive force generated by the electromotive force
generating unit is greater than or equal to the predetermined threshold.
[0055] With the above configuration, the rail breakage detection device 100 according to
Embodiment 1 can detect the rail breakage with a simple configuration and reduce the
maintenance load.
[0056] Further, the first core part and the second core part of the rail 5 breakage detection
device according to Embodiment 1 are characterized in that they are made of a magnetic
material.
[0057] With the above configuration, in the rail breakage detection device 100 according to
Embodiment 1, the positions where the first coil 112a and the second coil 112b are provided
can be changed accordingly, and thus the configuration of the rail breakage detection device
100 can be simplified.
[0058] Further, the first core part and the second core part of the rail breakage detection
device according to Embodiment 1 are characterized in that each part has a gap therein.
[0059] With the above configuration, in the rail breakage detection device 100 according to
Embodiment 1, it is easy to attach the first core part 111a and the second core part 111b to
the first cable 41a and the second cable 41b, respectively.
[0060] Further, the rail breakage detection device according to Embodiment 1 is
characterized in that the direction of the normal vector of the opening plane formed in an
inner side of the first core part and the direction of the current flowing through the first cable
are parallel and the direction of the normal vector of the opening plane formed in an inner
side of the second core part and the direction of the current flowing through the second cable
are parallel.
[0061] With the above configuration, the rail breakage detection device 100 according to
Embodiment 1 can accurately detect the current variations generated in the first cable 41a
and the second cable 41b.
[0062] Embodiment 2
A configuration of a rail breakage detection device 200 according to Embodiment 2 of the
present disclosure will be described. Note that description of the configurations which are
the same as or corresponding to those of Embodiment 1 will be omitted, and only different
portions of the configurations will be described. The rail breakage detection device 100
according to Embodiment 1 is configured to detect a case where imbalance occurs in the
current variations of the return currents flowing through the first cable 41a and the second
cable 41b, that is, a moment when a rail is broken. In contrast, in the rail breakage
40 detection device 200 according to Embodiment 2, it is possible to detect a case where
imbalance exists in the return currents flowing through the first cable 41a and the second
cable 41b; that is, it can detect a state in which a rail is broken.
[0063] FIG. 9 shows an example of a configuration of the rail breakage detection device 200
according to Embodiment 2. As shown in FIG. 9, the rail breakage detection device 200 is
configured to have a Hall element 113 instead of the first coil 112a and the second coil 112b.
The Hall element 113 is an electromagnetic conversion element which utilizes the Hall effect.
[0064] The FIG. 9 shows a configuration in which the electromotive force generating unit 11
is attached to the first cable 41a and the second cable 41b. However, rail breakage can also
be detected by using a configuration in which the electromotive force generating unit 11 is
attached to the third cable 43a and the fourth cable 43b. In the following, the case in which
10 the electromotive force generating unit 11 is attached to the first cable 41a and the second
cable 41b will be described.
[0065] The first core part 111a and the second core part 111b are made of a magnetic material
and generate a magnetic flux in accordance with the return currents flowing through the first
cable 41a and the second cable 41b. The first core part 111a and the second core part 111b
are mechanically connected.
[0066] In the first core part 111a and the second core part 111b according to Embodiment 2,
when the return currents of the same magnitude and direction flow in the first cable 41a and
the second cable 41b, a first magnetic flux generated in the first core part 111a and a second
magnetic flux generated in the second core part 111b cancel each other out. That is, in the
first core part 111a and the second core part 111b, when the return currents of the same
magnitude and direction flow through the first cable 41a and the second cable 41b, no
magnetic flux is generated, and when the return currents flowing through the first cable 41a
and the second cable 41b are imbalanced, a magnetic flux is generated. The first core part
111a and the second core part 111b can be made, for example, by twisting an annular member
at its intermediate position an odd number of times into an eight-character shape, the
annular member being made of a magnetic material.
30 [0067] The Hall element 113 is placed in a gap provided in either the first core part 111a or
the second core part 111b. The Hall element 113 is connected to the breakage determination
unit 12. Further, the Hall element 113 is supplied with a constant current from the
breakage determination unit 12.
[0068] The Hall element 113 generates an electromotive force in accordance with the
magnetic flux generated by the first core part 111a and the second core part 111b. The
breakage determination unit 12 measures the electromotive force generated by the Hall
element 113. The breakage determination unit 12 determines the breakage when the
electromotive force generated by the Hall element 113 is greater than or equal to a threshold.
The threshold is determined, for example, by measuring in advance the values of the
electromotive force generated by the Hall element 113 when the train 1 travels with the first
rail 2a and the second rail 2b unbroken and by calculating an average and a standard
deviation of the electromotive force. Specifically, the threshold is determined based on
Equation (2).
[0069] The first core part 111a and the second core part 111b are configured such that a
magnetic flux is generated when the return currents flowing through the first cable 41a and
the second cable 41b are imbalanced. Therefore, the Hall element 113 generates an
electromotive force when the return currents flowing through the first 5 cable 41a and the
second cable 41b are imbalanced.
[0070] That is, the Hall element 113 constantly generates an electromotive force while
imbalance exists in the return currents flowing through the first cable 41a and the second
cable 41b.
[0071] Therefore, the rail breakage detection device 200 according to Embodiment 2 can
detect not only a moment when a rail is broken, but also a case where imbalance exists in the
return currents flowing through the first cable 41a and the second cable 41b; that is, it can
detect a state in which a rail is broken, and thereby the rail breakage can be detected more
accurately.
[0072] FIG. 10 shows a variation of the electromotive force generating unit 11. The first core
part 111a and the second coil 112b do not necessarily have a loop shape, and may have a
structure having a gap E and a gap F, respectively, as shown in FIG. 10. By making the
structure of the first core part 111a and the second coil 112b to have the gap E and the gap F,
respectively, attachment of the first core part 111a and the second coil 112b to the first cable
41a and the second cable 41b becomes easy.
[0073] The rail breakage detection device according to Embodiment 2 comprises:
the electromotive force generating unit including
the first core part that is provided annularly along the circumferential direction of the first
cable electrically connecting the electrical neutral point of the impedance bond to a
prescribed block section of the first rail, and made of a magnetic material to generate the first
magnetic flux in accordance with the return current flowing through the first cable, the
impedance bond electrically connecting the first rail and the second rail in a pair,
the second core part that is provided annularly along the circumferential direction of the
second cable electrically connecting the electrical neutral point of the impedance bond to a
prescribed block section of the second rail, is mechanically connected to the first core part,
generates the second magnetic flux in accordance with the return current flowing through
the second cable, and is made of a magnetic material to generate the second magnetic flux so
as to cancel the first magnetic flux out when the return current flowing through the second
cable is identical with the return current flowing through the first cable in terms of a
direction and a magnitude, and
the Hall element that is disposed in the gap provided in either the first core part or the
second core part to generate the electromotive force in accordance with a sum of the first
magnetic flux and the second magnetic flux; and
the breakage determination unit that determines that the first rail or the second rail is
broken based on the electromotive force generated by the Hall element of the electromotive
force generating unit.
[0074] With the above configuration, the rail breakage detection device 5 200 according to
Embodiment 2 can detect the case where imbalance exists in the return currents flowing
through the first cable 41a and the second cable 41b; that is, it can detect the state in which a
rail is broken, and thereby rail breakage can be detected more accurately.
[0075] Embodiment 3
Next, a rail breakage result management system which manages breakage detection results
of rails using the rail breakage detection device according to Embodiment 1 or Embodiment 2
will be described. FIG. 11 is a diagram showing an example of a configuration of the rail
breakage result management system according to Embodiment 3 which manages the
breakage detection results of the rails using the rail breakage detection device according to
Embodiment 1 or Embodiment 2. As shown in FIG. 11, the rail breakage result
management system includes the rail breakage detection device 100 and a management
server 7.
[0076] The breakage determination unit 12 of the rail breakage detection device 100 includes
an information output unit 121. The information output unit 121 is connected to the
management server 7 via a network. The network is, for example, a local area network
(LAN), a wide area network (WAN), a bus, or a private line. If the breakage detection
results of the rails and management numbers of the block sections can be outputted to the
management server 7, the information output unit 121 does not need to be included in the
breakage determination unit 12, and communication equipment or the like separated from
the breakage determination unit 12 may be used.
[0077] The breakage determination unit 12 stores the management numbers of the block
sections in advance. The breakage detection results of the rails and the management
numbers of the block sections are outputted to the management server 7 from the
information output unit 121 via the network. The management numbers of the block
sections are the numbers assigned to each of the block sections of the rails, and each are the
number for specifying a position of a block section.
[0078] The management server 7, which is a server apparatus operated by a railway
management business operator, etc., receives the breakage detection results of the rails
outputted from the information output unit 121 and the management numbers of the block
sections via the network and stores the breakage detection results of the rails and the
40 management numbers of the block sections in association with each other.
[0079] The management server 7 includes a control unit 71a which controls the entire
operation of the management server 7, an information storage unit 71b which stores
information etc., received via the network, and a communication unit 71c which sends and
receives information via the network.
[0080] The information storage unit 71b stores the breakage detection results of the rails and
the management numbers of the block sections that are received from the 5 information output
unit 121 via the network, in association with each other.
[0081] FIG. 12 is a diagram showing a configuration of the management server 7. The
management server 7 can be implemented by software control by a CPU 1001b executing a
program stored in a memory 1002b, as shown in FIG. 12.
[0082] FIG. 13 is a diagram showing an example of a configuration of the rail breakage result
management system in which the rail breakage detection device 100 is provided in each of
the block sections of the rails. The rail breakage detection device 100 installed to the
impedance bond 4 individually provided in each block section outputs the breakage detection
results of the rails and the management number of the block section to the management
server 7 via the network. The management server 7 manages the detection results for each
block section. Since an identification number is assigned to each block section, the rail
breakage result management system can manage appropriately in which block section the
breakage occurs.
[0083] The rail breakage result management system according to Embodiment 3 includes:
the rail breakage detection device according to Embodiment 1 or 2; and
the management server to store the breakage detection result of the rails detected by the
rail breakage detection device and the management number in association with each other,
the management number being assigned individually to a block section of rails, wherein
the rail breakage detection device comprises the information output unit to output the
breakage detection result of the rails and the management number to the management
server via the network.
[0084] With the above configuration, the rail breakage result management system according
to Embodiment 3 can appropriately manage the block section in which the breakage occurs.
[0085] Within the scope of the invention, some of the embodiments disclosed here can be
freely combined, and each of the embodiments can be accordingly modified or omitted.
Description of Symbols
[0086]
100, 200 rail breakage detection device,
1 train,
2a first rail,
2b second rail,
3a, 3b rail insulating member,
4 impedance bond,
5 substation,
6 overhead line,
7 management server,
11 electromotive force generating unit,
12 breakage determination 5 unit,
41a first cable,
41b second cable,
42a first winding,
42b second winding,
10 43a third cable,
43b fourth cable,
44 fifth cable,
71a control unit,
71b information storage unit,
15 71c communication unit,
111a first core part,
111b second core part,
112a first coil,
112b second coil,
20 113 Hall element,
121 information output unit,
1001a, 1001b CPU,
1002a, 1002b memory

We Claim:
1. A rail breakage detection device comprising:
an electromotive force generating 5 unit including
a first core part that is provided annularly along a circumferential direction of a first cable
electrically connecting an electrical neutral point of an impedance bond to a prescribed block
section of a first rail, the impedance bond electrically connecting the first rail and a second
rail in a pair, a second core part that is provided annularly along a circumferential direction of a second
cable electrically connecting the electrical neutral point of the impedance bond to the
prescribed block section of the second rail, a first coil that is wound around the first core part to generate a first electromotive force in accordance with a current variation occurring in the first cable, and
a second coil that is connected electrically to the first coil, is wound around the second core
part to generate a second electromotive force in accordance with a current variation occurring
in the second cable, and generates the second electromotive force so as to cancel the first
electromotive force out when the current variation occurring in the second cable is identical
with the current variation occurring in the first cable in terms of a direction and a
magnitude, the electromotive force generating unit generating an electromotive force being a sum of
the first electromotive force and the second electromotive force; and
a breakage determination unit to determine that the first rail or the second rail is broken
based on the electromotive force generated by the electromotive force generating unit.
2. The rail breakage detection device according to claim 1, wherein the first core part and the
second core part are made of a magnetic material.
3. A rail breakage detection device comprising: an electromotive force generating unit including
a first core part that is provided annularly along a circumferential direction of a first cable
electrically connecting an electrical neutral point of an impedance bond to a prescribed block
section of a first rail, and is made of a magnetic material to generate a first magnetic flux in
accordance with return current flowing through the first cable, the impedance bond
electrically connecting the first rail and a second rail in a pair,
a second core part that is provided annularly along a circumferential direction of a second
cable electrically connecting the electrical neutral point of the impedance bond to the
prescribed block section of the second rail, is mechanically connected to the first core part,
generates a second magnetic flux in accordance with return current flowing through the
second cable, and is made of a magnetic material to generate the second magnetic flux so as
to cancel the first magnetic flux out when the return current flowing through the second
cable is identical with the return current flowing through the first cable in terms of a
direction and a magnitude, and a Hall element that is disposed in a gap provided in either the first core part or the second core part to generate an electromotive force in accordance with a sum of the first magnetic
flux and the second magnetic flux; and a breakage determination unit to determine that the first rail or the second rail is broken based on the electromotive force generated by the Hall element of the electromotive 5 force generating unit.
4. The rail breakage detection device according to any one of claims 1 to 3, wherein the
breakage determination unit determines that the first rail or the second rail is broken when
an electromotive force generated by the electromotive force generating unit is greater than or
equal to a predetermined threshold.
5. The rail breakage detection device according to any one of claims 1 to 4, wherein the first
core part and the second core part each have a gap therein.
6. The rail breakage detection device according to any one of claims 1 to 5, wherein a direction
of a normal vector of an opening plane formed in an inner side of the first core part and a
direction of current flowing through the first cable are parallel, and a direction of a normal
vector of an opening plane formed in an inner side of the second core part and a direction of
current flowing through the second cable are parallel.
7. A rail breakage result management system comprising:
the rail breakage detection device according to any one of claims 1 to 6; and
a management server to store a breakage detection result of rails detected by the rail
breakage detection device and a management number in association with each other, the
management number being assigned individually to a block section of the rails, wherein
the rail breakage detection device comprises an information output unit to output the
breakage detection result of the rails and the management number to the management
server via a network. g unit.