ATC ANTENNA DEVICE, ATC SIGNAL TRANSMISSION DEVICE AND VEHICLE

Abstract

An ATC antenna device provided on a body of a lead car to receive signals from outside. In the ATC antenna device, a pair of ATC antenna coils is disposed symmetrically with respect to a center line of the body as viewed in a traveling direction of the body, and the paired ATC antenna coils are connected in series and are of opposite phase. An ATC antenna support device is attached to the body to support the paired ATC antenna coils, and is disposed asymmetrically with respect to the center line.

Claims

1. An ATC antenna device provided on a body of a lead car to receive signals from outside by electromagnetic coupling, the ATC antenna device comprising: a pair of ATC antenna coils disposed symmetrically with respect to a center line of the body as viewed in a traveling direction of the body, the paired ATC antenna coils being connected in series and oppositely phased; and an ATC antenna support attached to the body to support the paired ATC antenna coils and disposed asymmetrically with respect to the center line.

2. The ATC antenna device according to claim 1, wherein the ATC antenna support supports each of the ATC antenna coils in a same lateral direction when as viewed in the traveling direction of the body.

3. The ATC antenna device according to claim 1, wherein the ATC antenna support is formed of a non-magnetic metal material, a reinforced plastic, or a combination thereof.

4. (canceled)

5. An ATC signal transmission device comprising: the ATC antenna device according to claim 1; and a receiver to receive an induction voltage signal output by the ATC antenna device.

6. (canceled)

7. A car comprising: the ATC antenna device according to claim 1; and a body having a bottom to which the ATC antenna device is attached.

8. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is a diagram illustrating an ATC antenna device according to Embodiment 1 of the present disclosure, as viewed from the front of a car;

[0016] FIG. 2 is a diagram illustrating the ATC antenna device of FIG. 1, as viewed from the side of the car;

[0017] FIG. 3 is a block diagram illustrating a configuration of a control system for performing automatic train control;

[0018] FIG. 4 is a diagram illustrating a relationship between an ATC antenna and a direction of the AC magnetic flux generated at an ATC ground device;

[0019] FIG. 5 is a diagram illustrating how AC voltage induced by the AC magnetic flux generated at the ATC ground device is amplified;

[0020] FIG. 6 is a diagram illustrating a relationship between an ATC antenna and a direction of magnetic flux that occurs due to return current;

[0021] FIG. 7 is a diagram illustrating AC voltage, which is induced by the magnetic flux that occurs due to return current, being offset;

[0022] FIG. 8 is a diagram illustrating a magnetic circuit through which AC magnetic flux flows that occurs at a traction motor, traction motor cables, and the like;

[0023] FIG. 9 is a diagram illustrating a direction of the AC magnetic flux that occurs at the traction motor cables and the traction motor body in a conventional ATC antenna device;

[0024] FIG. 10 is a diagram illustrating how AC voltage induced by AC magnetic flux that occurred at the traction motor cables and the traction motor body in a conventional ATC antenna device is amplified;

[0025] FIG. 11 is a diagram illustrating a direction of the AC magnetic flux that occurred at the traction motor cables and the traction motor body in the ATC antenna device of FIG. 1;

[0026] FIG. 12 is a diagram illustrating an offsetting of AC voltage induced by AC magnetic flux that occurred at the traction motor cables and the traction motor body in the ATC antenna device of FIG. 1;

[0027] FIG. 13 is a diagram of an ATC antenna device according to Embodiment 2 of the present disclosure, as viewed from the front of the car;

[0028] FIG. 14 is a diagram illustrating a magnetic circuit through which AC magnetic flux flows that occurred at the traction motor cables and the traction motor body due to AC flowing through the traction motor;

[0029] FIG. 15 is a diagram illustrating an ATC antenna device according to Embodiment 3 of the present disclosure, as viewed from the front of the car;

[0030] FIG. 16 is a diagram illustrating an ATC antenna device according to Embodiment 4 of the present disclosure, as viewed from the front of the car; and

[0031] FIG. 17 is a diagram illustrating an ATC antenna device according to Embodiment 5 of the present disclosure, as viewed from the front of the car.

DESCRIPTION OF EMBODIMENTS

[0032] Hereinafter, embodiments of the present disclosure are described with reference to the drawings.

Embodiment 1

[0033] First, Embodiment 1 of the Present Disclosure is Described.

[0034] FIG. 1 illustrates an ATC antenna device according to Embodiment 1 of the present disclosure, as viewed from the front of a car. FIG. 2 illustrates the ATC antenna device as viewed from a side of the car. FIG. 3 illustrates a control system for performing automatic train control (ATC). As illustrated in FIGS. 1 and 2, a body 1 is a body of rolling stock traveling on rails 3. An ATC antenna device 100 is attached to the bottom portion of an underfloor frame 1a of the body 1.

[0035] The ATC antenna device 100 is provided on the body 1 of the lead car of rolling stock. The ATC antenna device 100 receives ATC signals (speed signals) from an ATC ground device 5 that is laid between the rails 3. The ATC antenna device 100 includes an ATC antenna 4 (a pair of ATC antenna coils 4a and 4b) disposed symmetrically with respect to a center line AX of the body 1 as viewed in the traveling direction of the body 1, and an ATC antenna support device 2 that is attached to the car to support the ATC antenna coils 4a and 4b and is asymmetrically disposed with respect to the center line AX. The ATC antenna support device 2 supports the paired ATC antenna coils 4a and 4b from the same lateral direction (right side in FIG. 1) as viewed in the traveling direction of the body 1.

[0036] The ATC antenna support device 2 includes two vertically extending ATC antenna support bars 2a. The two ATC antenna support bars 2a are disposed to the right and to the left of the center line of the body 1 with a prescribed distance therebetween. The top end of the two ATC antenna support bars 2a are fixed to the bottom portion of the underfloor frame 1a.

[0037] The ATC antenna support device 2 includes a horizontally extending ATC antenna support base 2b that is suspended from both bottom ends of the two ATC antenna support bars 2a.

[0038] The ATC antenna support device 2 includes ATC antenna attaching members 2c both of which are disposed on the bottom portion of the ATC antenna support base 2b, and oriented in the same lateral direction. The ATC antenna 4, namely, the paired ATC antenna coils 4a and 4b are fixedly attached to the ATC antenna attaching members 2c, and are oriented in the same lateral direction.

[0039] As above, the ATC antenna support device 2 is integrally formed by the ATC antenna support bars 2a, the ATC antenna support base 2b, and the ATC antenna attaching members 2c, which are fastened or fixed together with bolts and the like, or welded together and the like.

[0040] In the ATC antenna support device 2, the left and right ATC antenna coils 4a and 4b of the ATC antenna 4 are attached to either the right side or the left side of the ATC antenna attaching members 2c. In other words, the ATC antenna support device 2 is formed in an asymmetrical shape with respect to the ATC antenna 4 (the paired ATC antenna coils 4a and 4b). With the ATC antenna 4 (the paired ATC antenna coils 4a and 4b) attached to the ATC antenna attaching members 2c with bolts and the like, the ATC antenna support device 2 is affixed with bolts and the like to the bottom portion of the underfloor frame 1a of the body 1.

[0041] The position in the right-and-left direction of the ATC antenna support device 2 fixed to the underfloor frame la, as illustrated in FIG. 1, is not a position that is symmetrical with respect to the center of the body 1. In contrast to this, the ATC antenna 4, namely, the paired ATC antenna coils 4a and 4b attached to the ATC antenna support device 2 are disposed symmetrically with respect to the center line AX of the body 1.

[0042] As illustrated in FIG. 1, the ATC ground device 5 is laid at a ground point between the left and right rails 3 to transmit speed signals to a car side for automatic train control. The ATC ground device 5 is a rectangular loop-shaped coil. This coil is installed such that the loop is horizontal between the left and right rails 3. The coil includes a coil side 5a that is close to and parallel to the left rail 3, and a coil side 5b that is close to and parallel to the right rail 3.

[0043] As illustrated in FIG. 2, a bogie frame 9 is installed on the bottom portion of the body 1. Wheels 10 are attached to the bogie frame 9. When the lead car is the motive power car, a traction motor 7 is mounted in the bogie frame 9. Rotary drive of the traction motor 7 causes the wheels 10 to rotate, thereby moving the body 1 along the rails 3. An inverter 15, which is installed beneath the floor of the body 1, and the traction motor 7 are connected together via traction motor cables 8. The traction motor 7 is driven by AC passing through the traction motor cables 8 from the inverter 15.

[0044] The ATC antenna support device 2 is disposed in a front position separated from the bogie frame 9 by a prescribed distance. A rail guard 11 is installed on the bottom portion of the front-most area of the body 1. The ATC antenna support device 2 is installed between the rail guard 11 and the bogie frame 9.

[0045] As illustrated in FIG. 3, a ground transmitter 12 is provided on the ground side. AC flows from the ground transmitter 12 to the ATC ground device 5 at a frequency in accordance with a command speed to be transmitted. The electromagnetic coupling of the AC induces AC voltage in the antenna coils 4a and 4b of the ATC antenna 4 on the car side. A receiving circuit 13 and the ATC control device 14 thereby detect the command speed, and the command speed is then input to the inverter 15. The inverter 15 drives the traction motor 7 at this command speed.

[0046] Next, the operation of the ATC antenna device 100 according to Embodiment 1 is described.

[0047] In the ground transmitter 12, a different frequency is set for each target speed signal, and AC of the frequency corresponding to the command speed passes through the ATC ground device 5. When current flows through a conductive wire, magnetic flux occurs around the conductive wire in accordance with the right-hand screw rule. In the case of AC, AC magnetic flux occurs in which a direction changes at the same frequency as the current.

[0048] Therefore, as illustrated in FIG. 4, AC magnetic fluxes 6a and 6b having the same frequency as the AC occurs around the coil sides 5a and 5b of the ATC ground device 5. The ATC ground device 5 is a loop shaped coil. The AC magnetic flux 6a, which occurs due to AC flowing through the left coil side 5a parallel to the rails 3, and the AC magnetic flux 6b, which occurs due to AC flowing through the right coil side 5b parallel to the rails 3, flow in directions opposite to each other as illustrated in FIG. 4. Portions of the AC magnetic fluxes 6a and 6b, which occur due to the ATC ground device 5, pass through the ATC antenna 4. AC voltage is induced in the ATC antenna 4 due to the AC magnetic fluxes 6a and 6b.

[0049] The AC magnetic flux 6a mainly passes through the ATC antenna coil 4a on the left, whereas the AC magnetic flux 6b mainly passes through the ATC antenna coil 4b on the right. Therefore, AC voltages are induced in opposite directions in the left and right ATC antenna coils 4a and 4b. The ATC antenna coils 4a and 4b on the left and right are connected in series and are of opposite phase as illustrated in FIG. 3. As such, as illustrated in FIG. 5, the AC voltages having opposite directions in the left and right ATC antenna coils 4a and 4b become a larger AC voltage amplified on the circuit where the AC voltages have the same polarity. The receiving circuit 13 detects a frequency based on the amplified AC voltage, which enables the ATC control device 14 to determine the command speed.

[0050] The AC magnetic flux 6a, which occurs due to AC flowing through the left coil side 5a, is what mainly passes through the left ATC antenna coil 4a, and the AC magnetic flux 6b, which occurs due to AC flowing through the right coil side 5b, also passes through the ATC antenna coil 4a. However, the distance between the left ATC antenna coil 4a and the right coil side 5b is greater than the distance between the left ATC antenna coil 4a and the left coil side 5a. Given that the magnitude of the magnetic flux is inversely proportional to the square of the distance, the magnitude of the AC magnetic flux 6b is substantially smaller than the AC magnetic flux 6a, and thus the influence on the alternating voltage detected is rather small. The same applies to the right ATC antenna coil 4b.

[0051] Return current from other cars flows through the rails 3 and such current causes magnetic flux to occur around the rails 3. As illustrated in FIG. 6, the direction of return current flowing through the rails 3 is the same for the left and right rails and the direction of the resulting magnetic flux is also the same. Typically, return current is direct current, but when the magnitude of the current value changes and the magnitude of the resulting magnetic fluxes 16a and 16b changes, the voltage is induced in the ATC antenna 4. In such a case, as illustrated in FIG. 7, given that the directions of the magnetic fluxes 16a and 16b are the same, the AC voltages induced are also in phase and cancel each other out. As such, since the ATC antenna coils 4a and 4b are connected in series and are of opposite phase, the voltages are not erroneously detected as the ATC signals.

[0052] Also, as illustrated in FIG. 2, when the lead car is the motive power car, the traction motor 7 is mounted on the bogie frame 9 that is near the ATC antenna 4 and the AC supplied from the inverter 15 (refer to FIG. 5) flows through the traction motor 7 and the traction motor cables 8. AC flows due to the square-wave AC voltage from the inverter 15, and includes lots of harmonic wave components. When the AC containing harmonic wave components flows through the traction motor 7 and the traction motor cables 8, AC magnetic flux 17 containing frequency components of fundamental waves and harmonic waves occurs. Also, the bogie frame 9, the underfloor frame 1a of the body 1, the wheels 10, the rails 3, the ATC antenna support device 2, and the like are magnetic bodies, and the magnetic bodies are arranged close to one another so as to form a magnetic circuit 18. As a result, as illustrated in FIG. 8, the AC magnetic flux 17, which contains frequency components of fundamental waves and harmonic waves, occurring at the traction motor cables 8 and the traction motor 7 flows around the formed magnetic circuit 18.

[0053] A conventional ATC antenna support device 60, as illustrated in FIG. 9, includes ATC antenna support bars 60a on the left and right, an ATC antenna support base 60b, and two ATC antenna attaching members 60c, which are in a horizontally symmetrical configuration around the center line AX. Thus, when flowing through the ATC antenna support device 60, the AC magnetic flux 17 splits to the left and right ATC antenna bars 60a, passes through the ATC antenna coils 4a and 4b, and then flows to the rails 3. The AC magnetic flux 17a that flows through the left ATC antenna support bar 60a passes through the ATC antenna coil 4a from the left side, whereas the AC magnetic flux 17b that flows through the right ATC antenna support bar 60a passes through the ATC antenna coil 4b from the right side. Thus, AC voltages that are induced in the ATC antenna coils 4a and 4b by the AC magnetic fluxes 17a and 17b are of opposite phase.

[0054] Therefore, as illustrated in FIG. 10, the ATC antenna coils 4a and 4b are connected in series and are of opposite phase, and thus an amplified voltage is obtained from the AC voltages that are induced in the ATC antenna coils 4a and 4b by the AC magnetic fluxes 17a and 17b. Consequently, when the frequency of the fundamental wave and the harmonic wave of AC flowing from the inverter 15 to the traction motor 7 matches with a frequency corresponding to an ATC speed, and, the amplified AC voltage exceeds a threshold for ATC speed detection, there is a possibility that a command speed at a ground location where the ATC ground device 5 is not installed might be erroneously detected.

[0055] To the contrary, the configuration of the ATC antenna support device 2 according to Embodiment 1, is horizontally asymmetrical as illustrated in FIG. 11. Therefore, the AC magnetic flux 17a flowing through the left ATC antenna support bar 2a passes through the left ATC antenna coil 4a from the right side, and the AC magnetic flux 17b flowing through the right ATC support bar 2a likewise passes through the right ATC antenna coil 4b from the right side. Thus, AC voltages induced in the ATC antenna coils 4a and 4b by the AC magnetic fluxes 17a and 17b are in phase. Given that the ATC antenna coil 4a and the ATC antenna coil 4b are connected in series and are of opposite phase, AC voltages induced in the left and right ATC antenna coils 4a and 4b cancel each other out. This, as a result, enables erroneous detection of ATC command speeds to be prevented. In FIG. 11, since the ATC antenna coils 4a and 4b are attached to the left side of the ATC antenna attaching members 2c, the AC magnetic flux 17 passes through the ATC antenna coils 4a and 4b from the right side. If the ATC antenna coils 4a and 4b are attached to the right side of the ATC antenna attaching members 2c, then the AC magnetic flux 17 will pass through the ATC antenna coils 4a and 4b from the left side, likewise thereby preventing erroneous detection of ATC command speeds.

[0056] As such, according to the ATC antenna device 100 of the present disclosure, even if AC magnetic flux 17 , which has fundamental wave and harmonic wave frequency components, occurs due to AC flowing through the traction motor 7 and the traction motor cables 8, and flows through the magnetic circuit 18 including the underfloor frame 1a, the ATC antenna support device 2, the rails 3, the wheels 10, the bogie frame 9, and the like, passing through the ATC antenna coils 4a and 4b in which AC voltages are thereby induced, the induction voltages in phase cancel each other out because the ATC antenna coils 4a and 4b are connected in series and are of opposite phase, as illustrated in FIG. 12. This enables erroneous detection of ATC command speeds to be prevented even when the AC magnetic flux 17 (17a and 17b) flows around the magnetic circuit 18.

Embodiment 2

[0057] Next, Embodiment 2 of the Present Disclosure is Described.

[0058] In the ATC antenna device 100 according to the previously described Embodiment 1, the ATC antenna support device 2 is configured so as to be horizontally asymmetrical. The ATC antenna device 100 according to Embodiment 2 includes an ATC antenna support device 20 instead of the ATC antenna support device 2. The ATC antenna support device 20 includes ATC antenna support bars 20a on the left and right, an ATC antenna support base 20b, and two ATC antenna attaching members 20c. As illustrated in FIG. 13, the ATC antenna support device 20 is horizontally symmetrical with respect to the center line AX, and the ATC antenna support device 20 is constructed by components all made of non-magnetic metal materials, such as stainless steel and the like. In doing so, as illustrated in FIG. 14, the rail guard 11 on the front end of the body 1 serves as a magnetic body between the underfloor frame 1a of the body 1 and the rails 3. As such, a magnetic circuit 19 is formed by the underfloor frame 1a of the body 1, the rail guard 11, the rails 3, the wheels 10, the bogie frame 9, and the like. The AC magnetic flux 17, which occurs at the traction motor cables 8 and the traction motor 7 due to AC flowing through the traction motor 7, flows around the magnetic circuit 19 as illustrated in FIG. 14. Given that the ATC antenna support device 20 is constructed of non-magnetic metal materials, the AC magnetic fluxes 17a and 17b that flow through the ATC antenna support device 20 are rather weak, and thus the magnetic fluxes 17a and 17b that pass through the ATC antenna coils 4a and 4b are also rather weak. Thus, even if AC voltages are induced in the ATC antenna coils 4a and 4b by the magnetic fluxes 17a and 17b, the induced AC voltages do not exceed the threshold. This enables erroneous detection of ATC speed signals to be prevented.

[0059] The non-magnetic metal materials for use may include aluminum, alloys thereof, and the like.

Embodiment 3

[0060] Next, Embodiment 3 of the Present Disclosure is Described.

[0061] In the previously described Embodiment 2, the ATC antenna support device 20 is constructed by components all made of non-magnetic metal materials. The ATC antenna device 100 according to Embodiment 3, as illustrated in FIG. 15, includes an ATC antenna support device 30 instead of the ATC antenna support device 20. The ATC antenna support device 30 includes ATC antenna support bars 30a on the left and right, an ATC antenna support base 30b, and two ATC antenna attaching members 30c. The ATC antenna support device 30 is horizontally asymmetrical, and in this respect is the same as the ATC antenna support device 2 according to the previously described Embodiment 1. This enables erroneous detection of ATC speed signals to be prevented.

[0062] Also, the ATC antenna support device 30 is constructed by components made of non-magnetic metal materials. This further reduces the probability of erroneous detection of ATC speed signals.

Embodiment 4

[0063] Next, Embodiment 4 of the Present Disclosure is Described.

[0064] In the previously described Embodiment 2, the ATC antenna support device 20 is constructed of non-magnetic metal materials. The ATC antenna device 100 according to Embodiment 4 includes an ATC antenna support device 40 instead of the ATC antenna support device 20. The ATC antenna support device 40 includes ATC antenna support bars 40a on the left and right, an ATC antenna support base 40b, and two ATC antenna attaching members 40c. The ATC antenna support device 40 is in a horizontal symmetrical configuration with respect to the center line AX as illustrated in FIG. 16, but the material of the ATC antenna support device 40 is a combination of reinforced plastic materials and non-magnetic metal materials. Examples of reinforced plastic that may be used include glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), and the like. In such a way, the magnetic circuit 19 is formed as illustrated in FIG. 14. The AC magnetic flux 17 that passes through the ATC antenna coils 4a and 4b is rather weak, and the AC voltages induced in the ATC antenna coils 4a and 4b by the AC magnetic flux 17 do not exceed the threshold, thus enabling prevention of erroneous detection of ATC speed signals.

[0065] Also, the ATC antenna support device 40 may be constructed solely of reinforced plastic, which can improve the strength of the ATC antenna support device 2 and even reduce the weight thereof.

Embodiment 5

[0066] Next, Embodiment 5 of the Present Disclosure is Described.

[0067] In the previously described Embodiment 3, the ATC antenna support device 30, which is horizontally asymmetrical with respect to the center line, is constructed by components all made of non-magnetic metal materials. As illustrated in FIG. 17, the ATC antenna device 100 according to Embodiment 5 includes an ATC antenna support device 50 instead of the ATC antenna support device 30. The ATC antenna support device 50 includes ATC antenna support bars 50a on the left and right, an ATC antenna support base 50b, and two ATC antenna attaching members 50c. The ATC antenna support device 50 is horizontally asymmetrical, and in this respect is the same as the ATC antenna support device 2 according to the previously described Embodiment 1. This enables erroneous detection of ATC speed signals to be prevented.

[0068] Also, the ATC antenna support device 50 is made of a combination of reinforced plastic materials and non-magnetic metal materials. This further reduces the probability of erroneous detection of ATC speed signals.

[0069] Also, the ATC antenna support device 50 may be constructed solely of reinforced plastic. Doing so can improve the strength of the ATC antenna support device 2 and even reduce the weight thereof.

[0070] As described above, according to Embodiments 1, 3, and 5, the ATC antenna support devices 2, 30, and 50, which support the paired ATC antenna coils 4a and 4b, are asymmetrical with respect to the center of the body 1, and the paired ATC antenna coils 4a and 4b are symmetrical with respect to the center line AX of the body 1. As such, the AC magnetic flux 17, which occurs at the traction motor 7 and the traction motor cables 8, passes through the paired ATC antenna coils 4a and 4b in phase via the ATC antenna support device 2, 30, or 50. Given that the paired ATC antenna coils 4a and 4b are connected in series and are of opposite phase, the induction voltages caused by AC magnetic flux in phase and induced in each of the ATC antenna coils 4a and 4b cancel each other out. This, as a result, enables erroneous detection of ATC speed signals to be prevented by the AC magnetic flux 17 of the fundamental waves and harmonic waves that occur due to AC flowing through the traction motor 7.

[0071] Also, according to the previously described Embodiments 2, 3, 4, and 5, the ATC antenna support devices 20, 30, 40, and 50 are formed of non-magnetic metal materials or reinforced plastic or both. Accordingly, the AC magnetic flux 17 resulting from the traction motor current flowing through the ATC antenna coils 4a and 4b is substantially reduced, and this enables erroneous detection ATC command speeds to be prevented. Also, the use of reinforced plastic can improve the strength of the ATC antenna support devices 40 and 50 and even reduce the weight thereof.

[0072] The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.

INDUSTRIAL APPLICABILITY

[0073] The present disclosure, which is applied to rolling stock that perform ATC, is described as an example, but the present disclosure may also be applied to the automobile industry and general industries in the field of non-contact signal transmission utilizing magnetism.

REFERENCE SIGNS LIST

[0074] 1 Body [0075] 1a Underfloor frame [0076] 2 ATC antenna support device [0077] 2a ATC antenna support bar [0078] 2b ATC antenna support base [0079] 2c ATC antenna attaching member [0080] 3 Rail [0081] 4 ATC antenna [0082] 4a, 4b ATC antenna coil [0083] 5 ATC ground device [0084] 5a, 5b Coil side [0085] 6a, 6b AC magnetic flux [0086] 7 Traction motor [0087] 8 Traction motor cable [0088] 9 Bogie frame [0089] 10 Wheel [0090] 11 Rail guard [0091] 12 Ground transmitter [0092] 13 Receiving circuit [0093] 14 ATC control device [0094] 15 Inverter [0095] 16a, 16b Magnetic flux [0096] 17, 17a, 17b AC Magnetic flux [0097] 18 Magnetic circuit including ATC antenna support [0098] 19 Magnetic circuit including rail guard [0099] 20 ATC antenna support device [0100] 20a ATC antenna support bar [0101] 20b ATC antenna support base [0102] 20c ATC antenna attaching member [0103] 30 ATC antenna support device [0104] 30a ATC antenna support bar [0105] 30b ATC antenna support base [0106] 30c ATC antenna attaching member [0107] 40 ATC antenna support device [0108] 40a ATC antenna support bar [0109] 40b ATC antenna support base [0110] 40c ATC antenna attaching member [0111] 50 ATC antenna support device [0112] 50a ATC antenna support bar [0113] 50b ATC antenna support base [0114] 50c ATC antenna attaching member [0115] 60 ATC antenna support device [0116] 60a ATC antenna support bar [0117] 60b ATC antenna support base [0118] 60c ATC antenna attaching member [0119] 100 ATC antenna device