KR102691810B1 - Null-flux levitation apparatus for magnetic levitation vehicle and system - Google Patents

Abstract

The present invention proposes a null flux levitation device and system for a magnetic levitation vehicle. The null flux levitation device according to an embodiment of the present invention includes a null flux coil disposed closest to the magnet of the magnetic levitation vehicle, a propulsion coil disposed at the rear of the null flux coil, and a rear of the propulsion coil, It includes a first conductor plate disposed at the bottom of the propulsion coil.

Description

NULL-FLUX LEVITATION APPARATUS FOR MAGNETIC LEVITATION VEHICLE AND SYSTEM}

The present invention relates to null flux levitation devices and systems for magnetic levitation vehicles.

Magnetic levitation propulsion refers to levitating and propulsion from orbit at a certain height using electric magnetic force. Maglev vehicles include a bogie that levitates and propels non-contactly on and off track.

A magnetically levitated vehicle uses the attractive or repulsive force of electromagnets between the bogie and the track to propel the vehicle away from the track. In this way, the magnetic levitation system is propelled in a non-contact state with the orbit, so noise and vibration are low and high-speed propulsion is possible.

Magnetic levitation methods include a suction type that uses the attractive force of a magnet and a repulsion type that uses the repulsive force of a magnet. In addition, magnetic levitation methods include a superconducting method and a normal conduction method, depending on the principle of electromagnetism. The superconducting method has no electrical resistance and can obtain strong magnetic force, so it is applied to high-speed vehicles, while the normal conduction method is applied to medium-speed, short- to medium-distance vehicles.

The main force components acting on a maglev vehicle are levitation force, propulsion force, and guidance force. The magnetic levitation electromagnet is responsible for the levitation force, the linear motor is responsible for the propulsion force, and the guidance electromagnet is responsible for the guidance force.

A power supply is installed to supply power to the electromagnet, and the power supply must be stably controlled to stably generate levitation force and propulsion force.

Meanwhile, using such magnetic levitation vehicles, the development of a hypertube system that allows maglev vehicles to travel in a tube-type tunnel maintained in a vacuum state is currently underway.

In this regard, Korean Patent No. 10-1999790 (title of the invention: maglev train including energy harvester and infrastructure system on which maglev train runs) relates to a system related to a maglev vehicle that levitates and moves by magnetic force. It is starting.

Looking at the structure applied to this magnetic levitation vehicle 10, the levitation force, guidance force, and resistance force are generated through the action with the magnet on the vehicle due to the change in the magnetic field generated by the movement of the vehicle 10 and the induced electromotive force generated in each coil. It happens.

Referring to FIG. 1, a null flux cable connecting eight-shaped null flux coils 21 facing each other is disposed at the lower part of the travel path. At this time, an 8-shaped null flux coil 21 is placed as a levitation, guidance, and propulsion coil placed on the infrastructure structure, and the electromagnet 12 of the vehicle 11 is connected to the upper and lower coils of the null flux coil 21. It is located in between. As the vehicle electromagnet 12 moves, a magnetic field change occurs in the null flux coil 21, which causes it to float due to the action of the current induced in the coil 21 and the electromagnet 12.

Such a conventional induced-repulsion null-flux flotation device has a problem in that the force ripple becomes severe due to the discontinuous arrangement of the conductor plates.

In addition, during magnetic levitation, the traveling body travels tens of mm below the center of the coil, and when the conductor plate is placed at the center of the coil, a problem occurs in which the levitation force is reduced due to induced repulsion.

In addition, a problem may arise in which the guiding force characteristics in the low-speed section become weak due to the attractive force generated from the low-conductivity ferromagnetic material.

The purpose of some embodiments of the present invention is to provide a null-flux flotation device that can minimize the force ripple caused by separation of the conductor plate in the null-flux connected flotation device.

In addition, the purpose of the present invention is to provide a null flux flotation device system that can solve the problems of reduced flotation force and weak low-speed section guidance force characteristics due to induced repulsion.

As a technical means for achieving the above-described technical problem, the null flux levitation device according to the first embodiment of the present invention includes a null flux coil disposed closest to the magnet of the magnetic levitation vehicle, and a null flux coil disposed at the rear of the null flux coil. It includes a propulsion coil and a first conductor plate disposed at the rear of the propulsion coil and at a lower end of the propulsion coil.

The null-flux levitation device system according to the second embodiment of the present invention includes a first null-flux levitation device disposed along the side wall of the travel path of the maglev vehicle and a second null-flux levitation device disposed to face the first null-flux levitation device. A device including a first null flux levitation device, a first null flux coil disposed closest to the magnet of the magnetic levitation vehicle, a first propulsion coil disposed at the rear of the first null flux coil, and the first propulsion A second null flux coil disposed at the rear of the coil and comprising a lower conductor plate disposed at a lower end of the first propulsion coil, wherein the second null flux levitation device is disposed closest to the magnet of the magnetic levitation vehicle, the second null flux coil It includes a second propulsion coil disposed at the rear of the second null flux coil, and a lower conductor plate disposed at the rear of the second propulsion coil and at a lower end of the second propulsion coil.

The present invention has the effect of minimizing the force ripple caused by separation of the conductor plate in a null-flux connected flotation device.

In addition, the present invention has the effect of solving the problems of reduced levitation force and weak guidance force characteristics in low-speed sections due to induced repulsion.

1 is a schematic diagram showing a levitation device for a conventional magnetic levitation vehicle.
Figure 2 is a perspective view of a null flux flotation device according to an embodiment of the present invention.
3 is a diagram showing various examples of a conductor plate according to an embodiment of the present invention.
Figure 4 is a view showing various embodiments of the conductor plate of the null flux flotation device according to another embodiment of the present invention.
Figure 5 is a diagram showing a conductor plate of a null flux flotation device according to another embodiment of the present invention.
Figure 6 is a diagram showing various embodiments of a null flux flotation device for a conductor plate according to an embodiment of the present invention.
Figure 7 is a diagram showing another shape of a conductor plate according to an embodiment of the present invention.
Figure 8 is a diagram to explain that the edges of a conductor plate are chamfered according to an embodiment of the present invention.
Figure 9 is a schematic diagram of a null flux flotation system according to one embodiment of the present invention.
Figure 10 is a perspective view of the Null Flux flotation device of the Null Flux flotation system according to an embodiment of the present invention.
Figure 11 is a diagram for explaining the size of the conductor plate in the curved portion of the null flux flotation system according to an embodiment of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts unrelated to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be “connected” to another part, this includes not only cases where it is “directly connected,” but also cases where it is “electrically connected” with another element in between. . Additionally, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

The present invention relates to null flux levitation devices and systems for magnetic levitation vehicles.

Figure 1 is a schematic diagram showing a levitation device for a conventional magnetic levitation vehicle, Figure 2 is a perspective view of a null flux levitation device according to an embodiment of the present invention, and Figure 3 is a conductor plate according to an embodiment of the present invention. is a drawing showing various embodiments of, and Figure 4 is a drawing showing various embodiments of a conductor plate of a null flux flotation device according to another embodiment of the present invention, and Figure 5 is a drawing showing various embodiments of a null flux flotation device according to another embodiment of the present invention. It is a diagram showing a conductor plate of a flotation device, and Figure 6 is a diagram showing various embodiments of a null flux flotation device of a conductor plate according to an embodiment of the present invention, and Figure 7 is a diagram showing a conductor plate according to an embodiment of the present invention. is a drawing showing another shape, Figure 8 is a drawing to explain that the corners of the conductor plate are chamfered according to an embodiment of the present invention, and Figure 9 is a drawing of the null flux flotation system according to an embodiment of the present invention. It is a schematic diagram, Figure 10 is a perspective view of the null-flux flotation device of the null-flux flotation system according to an embodiment of the present invention, and Figure 11 is a diagram of the conductor plate at the curved portion of the null-flux flotation system according to an embodiment of the present invention. This is a drawing to explain the size.

Hereinafter, with reference to FIG. 2, a null-flux levitation device 100 (hereinafter referred to as ‘null-flux levitation device 100’) for a magnetic levitation vehicle according to an embodiment of the present invention will be briefly described.

The null flux flotation device 100 includes a null flux coil 110, a propulsion coil 120, and a first conductive plate 130.

The null flux coil 110 provides levitation force to the maglev vehicle, the propulsion coil 120 provides propulsion force to the maglev vehicle, and the first conductor plate 130 can provide guidance force to the maglev vehicle. there is. The null-flux levitation device 100 provides a guiding force to the magnetic levitation vehicle through the first conductor plate 130, and does not require a null-flux cable, which has the effect of significantly reducing manufacturing and maintenance costs. As an example, the null flux coil 110 may be formed in an 8-shape and may not include a cable connecting the null flux coils 110 facing each other.

Additionally, the null flux flotation device 100 may be configured by sequentially combining the null flux coil 110, the propulsion coil 120, and the first conductor plate 130.

In detail, the propulsion coil 120 is disposed at the rear of the null flux coil 110, and the first conductor plate 130 is disposed at the rear of the propulsion coil 120. Additionally, referring to FIG. 8, the null flux levitation device 100 may be arranged so that the null flux coil 110 is closest to the magnet 12 of the magnetic levitation vehicle. The magnet 12 of the above-described magnetic levitation vehicle may be a superconducting electromagnet or a permanent magnet, but is not limited thereto.

The first conductor plate 130 not only provides a guiding force to the magnetic levitation vehicle, but also provides the effect of cooling the heat generated from the null flux levitation device 100. In addition, the null flux flotation device 100 is coupled to the first conductor plate 130 and further includes a cooling device (not shown) that cools the heat generated in the first conductor plate 130, thereby improving cooling efficiency. It can be improved further. Illustratively, the above-described cooling device may be one of a cooling fin, cooling fan, heat pipe, or water cooling device, but is not limited thereto.

Hereinafter, with reference to FIGS. 3 to 6, various embodiments of the null flux flotation device 100 according to an embodiment of the present invention will be described.

The null flux flotation device 100 has a first conductor plate 130 disposed at the rear bottom of the propulsion coil 120 as shown in (a) of FIG. 3, or as shown in (b) of FIG. 3. A first conductor plate 130 may be disposed at the bottom of the rear of the propulsion coil 120, and a second conductor plate 140 may be disposed at the top of the rear of the propulsion coil 120. In other words, the null flux flotation device 100 is disposed in parallel with the first conductor plate 130 and may further include a second conductor plate 140 disposed on top of the propulsion coil 120. At this time, the first conductor plate 130 may be formed in a rectangular plate shape, and the second conductor plate 140 may have the same shape as the first conductor plate 130.

In another embodiment of the null flux flotation device 100, as shown in (c) of FIG. 3, the first conductor plate 130 is disposed at the rear bottom of the propulsion coil 120, and the propulsion coil 120 A dummy structure 150 may be placed at the top of the rear. At this time, the dummy structure 150 is made of a non-conductor, for example, fiber reinforced plastics (FRP), a polymer material, etc., and may have a shape symmetrical to the first conductor plate 130.

4 and 5, the first conductor plate 130, the second conductor plate 140, and the dummy structure 150 are L-shaped, ├ or ┤ shaped, formed to surround the corners of the propulsion coil. It may be a bent structure.

When the first conductor plate 130, the second conductor plate 140, and the dummy structure 150 are formed in a ├ or ┤ shape, the conductor plates can be easily attached to the guideway through fastening means (not provided). Can be combined. At this time, the position of the fastening means can be adjusted by adding or subtracting washers, liners, etc. from the fastening means, which has the effect of alleviating steps and unevenness in guideway construction.

On the other hand, when the first conductor plate 130 is placed only at the rear bottom of the propulsion coil 120, a dummy structure 150 having the same shape but made of a non-conductor is placed at the top to install the null flux flotation device 100. can facilitate.

Referring to Figure 6, the null flux flotation device 100 of the present invention can be installed using a molding material 160 in addition to a fastening method through a fastening means.

In other words, the null flux flotation device 100 is a combination of the null flux coil 110, the propulsion coil 120, and the first conductor plate 130, the null flux coil 110, the propulsion coil 120, and the first conductor. Molding formed to entirely surround the combination of the plate 130 and the second conductor plate 140 or the combination of the null flux coil 110, the propulsion coil 120, the first conductor plate 130, and the dummy structure 150. It may further include ash (160).

Referring to FIG. 7, unlike (a) and (b), the first conductor plate 130 or the second conductor plate 140, as shown in (c), is formed to have a predetermined area and is formed in the central area. An opening 132 may be formed. Accordingly, not only can the guidance and resistance characteristics be changed, but the cooling efficiency through the first conductor plate 130 or the second conductor plate 140 can be increased.

Additionally, referring to (a) of FIG. 8, the upper or lower rear edge of the first conductor plate 130, the second conductor plate 140, or the dummy structure 150 may be chamfered. At this time, a slot is formed in the guide way to correspond to the shape of the first conductor plate 130, the second conductor plate 140, or the dummy structure 150, and the first conductor plate 130 and the second conductor are placed in the slot. The installation position can be adjusted by inserting the plate 140 or the dummy structure 150.

In addition, referring to (b) of FIG. 8, the first conductor plate 130 includes a first extension portion 134 extending downward from the lower surface, and includes a second conductor plate 140 or a dummy structure ( 150) may include a second extension portion 144 extending upward from the upper surface. In other words, when installing the null flux flotation device 100, there is an effect that it can be easily installed by forming a hole in the first extension part 134 and the second extension part 144 and inserting a fastening means into the formed hole. .

In addition, the null flux flotation device 100 may further include a ferromagnetic plate (not shown) disposed between the propulsion coil 120 and the first conductor plate 130 or the second conductor plate 140. Illustratively, the ferromagnetic plate may be formed only in the area where the first conductor plate 130 and the propulsion coil 120 or the second conductor plate 140 and the propulsion coil 120 contact, but is not limited to this. The rear of the propulsion coil 120 may be formed in a plate shape with a predetermined area.

The ferromagnetic plate serves to prevent excessive guidance force and running resistance from being generated by the first conductor plate 130 or the second conductor plate 140 that provides guidance force. In addition, the ferromagnetic plate can provide the effect of strengthening the magnetic field for the propulsion coil 120 and the null flux coil 110, respectively. In addition, the shielding effect of the ferromagnetic plate provides the effect of reducing the magnetic field of the conductor plate 130, and the nonlinear induced repulsion force (guiding force) is partially offset by the attraction force, thereby alleviating nonlinearity.

In addition, the null flux levitation device 100 partially shields the magnetic field of the car box magnet through a ferromagnetic plate, reducing the driving resistance generated from external structures due to the vacuum tube and superconducting magnets used in magnetic levitation vehicles such as hypertubes, It has the effect of preventing the vacuum tube from growing unnecessarily. At this time, the material that can be used as a ferromagnetic plate is a material that is magnetic but has very low conductivity, and ferrite, laminated silicon steel plate, and other composite materials can be used.

Hereinafter, with reference to FIGS. 9 to 11, the null flux flotation system 200 according to an embodiment of the present invention will be described.

The null flux levitation device system 200 includes a first null flux levitation device 101 disposed along the side wall of the travel path of the maglev vehicle and a second null flux levitation device disposed to face the first null flux levitation device 101. Includes (102). Illustratively, a plurality of first null flux levitation devices 101 are disposed at a predetermined distance apart from each other along the first side wall of the travel path of the maglev vehicle, and a plurality of first null flux levitation devices 101 are disposed along the second side wall of the travel path of the maglev vehicle. The second null flux flotation devices 102 may be arranged to be spaced a predetermined distance apart from each other.

In addition, referring to (a) of FIG. 10, the first null flux levitation device 101 includes a first null flux coil 110a and a first null flux coil disposed closest to the magnet 12 of the magnetic levitation vehicle. It includes a first propulsion coil 120a disposed at the rear of 110a and a lower conductor plate 130a disposed at the rear of the first propulsion coil 120a and disposed at the lower end of the first propulsion coil 120a. . In addition, the first null flux flotation device 101 is disposed in parallel with the lower conductor plate 130a and may further include an upper conductor plate 140a disposed on top of the first propulsion coil 120a.

In addition, referring to (b) of FIG. 10, the second null flux levitation device 102 includes a second null flux coil 110b and a second null flux coil 110b disposed closest to the magnet of the magnetic levitation vehicle. It includes a second propulsion coil 120b disposed at the rear of the second propulsion coil 120b and a lower conductor plate 130b disposed at the lower end of the second propulsion coil 120b. In addition, the second null flux flotation device 102 is disposed in parallel with the lower conductor plate 130b and may further include an upper conductor plate 140b disposed on top of the second propulsion coil 120b.

Since the first and second null flux flotation devices 101 and 102 have the same configuration as the null flux flotation device 100 described above, detailed description will be omitted.

Referring to FIG. 11, the null flux levitation system 200 is located adjacent to the rotation axis among the first flux levitation device 101 and the second null flux levitation device 102 installed in the rotation section, that is, in the direction toward which the magnetic levitation vehicle is biased. The thickness of the conductor plates 130 and 140 of the null flux flotation device may be thicker or may be disposed closer to the center point between the upper conductor plate 130 and the lower conductor plate 140 of the null flux flotation device. there is.

Specifically, when a maglev vehicle is in a turning or branching section and a centripetal force is generated due to the shape of the path, a difference in guidance force may occur as shown in (a), which may cause the maglev vehicle to be biased to one side. there is. At this time, in order to minimize problems caused by the deviation of the guiding force in the rotation section or branch section, for the null flux generator on either side that requires an increase in the guiding force, as shown in (b), the conductor plate The design can be changed to make it thicker or to position the conductor plate more toward the center.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as single may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

10: Maglev vehicle
100: null flux flotation device
101: first null flux flotation device 102: second null flux flotation device
110: null flux coil
110a: first null flux coil 110b: second null flux coil
120: Propulsion coil
120a: first propulsion coil 120b: second propulsion coil
130: first conductor plate 132: opening
134: first extension part
140: second conductor plate
144: second extension part
130a, 130b: bottom conductor plate
140a, 140b: top conductor plate
150: Molding material 160: Dummy structure
200: Null flux flotation device system

Claims (29)

In the null flux levitation device for a magnetic levitation vehicle,
Null flux coil placed closest to the magnet of the maglev vehicle,
A propulsion coil disposed at the rear of the null flux coil and
A null-flux levitation device comprising a first conductor plate disposed at the rear of the propulsion coil, disposed at a lower end of the propulsion coil, providing a guiding force to the magnetic levitation vehicle, and cooling heat of the null-flux levitation device. . According to clause 1,
Null flux flotation device disposed in parallel with the first conductor plate and further comprising a second conductor plate disposed on top of the propulsion coil. According to claim 2,
The first conductor plate or the second conductor plate is a bent conductor plate of L shape, ├ or ┤ shape formed to surround the corner of the propulsion coil, respectively. In paragraph 1,
A null-flux levitation device further comprising a dummy structure made of a non-conductor, arranged parallel to the first conductive plate and positioned on top of the propulsion coil, and having the same shape as the first conductive plate. According to claim 4,
The first conductor plate and the dummy structure are L-shaped, ├ or ┤ shaped bent structures formed to surround the corners of the propulsion coil, null flux flotation device. According to claim 1,
A null-flux flotation device further comprising a molding material formed to entirely surround the null-flux coil, the propulsion coil, and the first conductor plate. The method of claim 1, 2 or 4,
The first conductor plate is formed to have a predetermined area, and an opening is formed in the central area. The method of claim 1, 2 or 4,
A null flux flotation device further comprising a ferromagnetic plate disposed between the first conductor plate and the propulsion coil. According to claim 1,
The first conductor plate is a null flux flotation device whose rear upper edge or lower edge is chamfered. According to clause 9,
The first conductor plate is a null flux flotation device including a first extension portion extending downward from the lower surface. In the null flux flotation system,
A first null flux levitation device disposed along the side wall of the travel path of the maglev vehicle, and
Including a second null flux flotation device disposed opposite to the first null flux flotation device,
The first null flux levitation device includes a first null flux coil disposed closest to the magnet of the magnetic levitation vehicle, a first propulsion coil disposed at the rear of the first null flux coil, and a rear of the first propulsion coil. It is disposed at the bottom of the first propulsion coil and provides a guiding force to the magnetic levitation vehicle, and includes a bottom conductor plate that cools the heat of the first null flux levitation device,
The second null flux levitation device includes a second null flux coil disposed closest to the magnet of the magnetic levitation vehicle, a second propulsion coil disposed at the rear of the second null flux coil, and a rear of the second propulsion coil. The null flux levitation device system is disposed at the bottom of the second propulsion coil and includes a lower conductor plate that provides guidance to the magnetic levitation vehicle and cools the heat of the second null flux levitation device. According to claim 11,
The first null-flux flotation device is disposed in parallel with a lower conductor plate of the first null-flux flotation device and further includes an upper conductor plate disposed on an upper end of the first propulsion coil,
The second null-flux flotation device is disposed in parallel with the lower conductor plate of the second null-flux flotation device and further includes an upper conductor plate disposed on top of the second propulsion coil. According to claim 12,
The upper conductor plate of the first null-flux flotation device or the lower conductor plate of the first null-flux flotation device is an L-shaped, ├ or ┤-shaped bent conductor plate formed to surround a corner of the first propulsion coil, respectively,
The upper conductor plate of the second null flux flotation device or the lower conductor plate of the second null flux flotation device is an L-shaped, ├ or ┤ shaped bent conductor plate formed to surround the corner of the second propulsion coil, respectively. Phosphorus, null flux flotation system. According to claim 11,
The first null-flux flotation device is arranged in parallel with the lower conductor plate of the first null-flux flotation device, is disposed at the top of the first propulsion coil, and has the same shape as the lower conductor plate of the first null-flux flotation device. It further includes a dummy structure made of an insulator,
The second null-flux flotation device is arranged in parallel with the lower conductor plate of the second null-flux flotation device, is disposed at the top of the second propulsion coil, and has the same shape as the lower conductor plate of the second null-flux flotation device. A null flux flotation device system further comprising a dummy structure made of an insulator to have a. According to claim 14,
The lower conductor plate of the first null flux flotation device and the dummy structure of the first null flux flotation device are L-shaped, ├ or ┤ shaped bent structures formed to surround the corners of the first propulsion coil,
The lower conductor plate of the second null flux flotation device and the dummy structure of the second null flux flotation device are L-shaped, ├ or ┤ shaped bent structures formed to surround the corners of the second propulsion coil, Null flux flotation system. According to claim 11,
The first null flux flotation device further includes a molding material formed to entirely surround the first null flux coil, the first propulsion coil, and the lower conductor plate in the first null flux flotation device,
The second null flux flotation device further includes a molding material formed to entirely surround the second null flux coil, the second propulsion coil, and the lower conductor plate in the second null flux flotation device. system. According to claim 11,
Among the first and second null flux flotation devices installed in the rotation section, the conductor plate of the null flux flotation device adjacent to the rotation axis is thicker, or the upper and lower conductor plates of the null flux flotation device are between them. Null flux flotation system, which is placed closer to the center point of. The method of claim 11, 12 or 14,
A null flux flotation device system further comprising a ferromagnetic plate disposed between the lower conductor plate and the propulsion coil. According to claim 11,
The lower conductor plate of the first null flux flotation device and the lower conductor plate of the second null flux flotation device have a rear lower edge or upper edge chamfered, null flux flotation device system. According to claim 19,
The lower conductor plate of the first null flux flotation device and the lower conductor plate of the second null flux flotation device include a first extension portion extending downward from the lower surface. In clause 12,
The lower conductor plate of the first null-flux flotation device, the lower conductor plate of the second null-flux flotation device, the upper conductor plate of the first null-flux flotation device and the upper conductor plate of the second null-flux flotation device are at the lower rear A null-flux flotation system, wherein the edges or top edges are chamfered. In clause 14,
The lower conductor plate of the first null-flux flotation device, the lower conductor plate of the second null-flux flotation device, the dummy structure of the first null-flux flotation device and the dummy structure of the second null-flux flotation device are located at the rear lower edge or Null-flux flotation system with chamfered upper edges. According to claim 21,
The lower conductor plate of the first null flux flotation device and the lower conductor plate of the second null flux flotation device include a first extension portion extending downward from the lower surface,
The upper conductor plate of the first null flux flotation device and the upper conductor plate of the second null flux flotation device include a second extension portion extending upward from the upper surface. According to claim 22,
The lower conductor plate of the first null flux flotation device and the lower conductor plate of the second null flux flotation device include a first extension portion extending downward from the lower surface,
The dummy structure of the first null-flux flotation device and the dummy structure of the second null-flux flotation device include a second extension portion extending upward from the upper surface. According to claim 2,
The first conductor plate and the second conductor plate are formed to have a predetermined area, and an opening is formed in the central area. According to claim 2,
The first conductor plate and the second conductor plate have rear upper or lower corners chamfered, a null flux flotation device. According to claim 4,
The first conductor plate and the dummy structure have a rear upper edge or lower edge chamfered, a null flux flotation device. According to claim 26,
The first conductor plate includes a first extension portion extending downward from the lower surface,
The second conductor plate is a null flux flotation device including a second extension portion extending upward from the upper surface. According to clause 27,
The first conductor plate includes a first extension portion extending downward from the lower surface,
The dummy structure is a null flux flotation device including a second extension portion extending upward from the upper surface.

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