WO2017045926A1

WO2017045926A1 - Magnetic levitation transportation system

Info

Publication number: WO2017045926A1
Application number: PCT/EP2016/070549
Authority: WO
Inventors: Pierre Bernstein; Jacques NOUDEM; Benoît BOUGLE
Original assignee: Ecole Nationale Superieure D'ingenieurs De Caen; Universite De Caen; Centre National De La Recherche Scientifique - Cnrs
Priority date: 2015-09-16
Filing date: 2016-08-31
Publication date: 2017-03-23
Also published as: FR3040963A1

Abstract

The invention relates to a magnetic levitation transportation system including: a magnetic guide means (11); a translatable vehicle (120) placed over said magnetic guide means, the vehicle having a frame (13); a set of magnetic levitation superconductor modules (140) located on the underside of the vehicle frame and aligned to face said magnetic guide means so as to levitate over said magnetic guide means; for each module, magnetic repulsion means (15) placed between the underside of the frame and said module, and designed to be mechanically secured to the underside of the frame and to levitate over said module.

Description

Magnetic levitation transport system

1. DOMAIN OF THE INVENTION

The invention relates to magnetic levitation transport.

More particularly, the invention relates to a magnetic levitation vehicle transport system.

Magnetic levitation is a well-known phenomenon whereby an object can be held in suspension at a distance above a surface by means of magnetic forces that compensate for the gravitational field on the object.

"Vehicle" means in the following of this document, any means of transport intended for the movement of persons or objects, such as metro, tramway, train, elevator, transport trolley, etc.

2. TECHNOLOGICAL BACKGROUND

In the remainder of this document and to illustrate the invention, we attempt to describe it in the field of public transport. But the invention is not limited to this particular field. It is of interest for any magnetic levitation transport system facing a similar or similar problem.

Magnetic levitation trains represent a considerable advance in the field of land transport. Unlike traditional trains running on steel rails, magnetic levitation trains are not in direct contact with their (or their) rail (s), which has a number of advantages. In fact, the absence of mechanical friction with the rails makes it possible to limit sound vibrations and mechanical vibrations, and to reach higher speeds.

Recently, manufacturers have developed a levitation transport technology based on the use of superconducting modules, called "MagLev-Cobra" (GG Sotelo, "Operational Test of a Full Scale Superconducting Maglev Vehicle Unit", 2011). As illustrated in FIGS. 1 to 3, this transport system 1 is composed of magnetic guiding rails 1a, 1b and a vehicle 2 movable above these rails. The vehicle 2 has a chassis 3 on which are fixed superconducting modules 4a, 4b each consisting of a cryostat comprising a cryogenic liquid in which bathes a The modules 4a, 4b located on the underside of the frame face the rails 1a, 1b so as to form a repulsive magnetic force allowing the vehicle 2 to levitate above the rails. In order to generate this repulsive magnetic force, the superconductor block is kept below its critical operating temperature thanks to the cryogenic liquid (-196 ° C for example with liquid nitrogen).

One of the main problems of manufacturers is that the repulsive forces exerted on each superconducting block must be efficiently transmitted to the module which contains it, then to the chassis on which it is fixed. However, the use of increasingly important repulsion forces (for example for vehicles of high weight) requires strengthening the mechanical links 5 between the modules and the chassis, which increases the thermal losses of connections and therefore the cost low temperature maintenance of modules.

It would therefore be particularly interesting to be able to design a magnetic levitation transport system using a device with little thermal loss, which would make it possible to use higher repulsion forces without incurring additional maintenance costs. in temperature of the praconductors.

3. OBJECTIVES OF THE INVENTION

The invention, in at least one embodiment, has in particular the objective of overcoming these various disadvantages of the state of the art.

More specifically, in at least one embodiment of the invention, one objective is to provide a magnetic levitation transport system that allows the use of high repulsion forces while preserving the temperature maintenance cost of superconductors. .

At least one embodiment of the invention also aims to provide a magnetically levitated transport system that thermally isolates the superconducting modules from the chassis.

Another objective of at least one embodiment of the invention is to provide a transport system that is simple to implement, while maintaining a reasonable cost of production. 4. PRESENTATION OF THE INVENTION

In a particular embodiment of the invention, there is provided a magnetic levitation transport system comprising:

a magnetic guiding means;

a vehicle movable in translation placed above said magnetic guiding means, the vehicle being provided with a frame;

a set of magnetic levitation superconducting modules located below the underside of the vehicle frame and aligned to face the magnetic guide means so as to levitate above the magnetic guide means;

for at least one module praconducteu r r, magnetic repulsion means placed between the underside of the frame and the upper face of said at least one superconducting module, said magnetic repulsion means being configured on the one hand to be mechanically integral with the underside of the chassis and on the other hand so as to create a magnetic repulsion force to put said magnetic repulsion means integral with the chassis levitated above said at least one superconducting module.

The general principle of the invention therefore consists in replacing the mechanical links between the superconducting modules and the chassis of the vehicle by a magnetic connection which ensures the transmission of magnetic repulsion forces to the chassis. The chassis of the vehicle is then magnetically levitated above the prconducteur modules themselves levitated above the magnetic guiding means. The invention thus proposes a double magnetic suspension system particularly well adapted to the transmission of magnetic repulsion forces to the vehicle. Thus, unlike conventional transport systems, the superconducting modules are no longer mechanically linked to the chassis, so it is possible to generate higher repulsion forces while preserving the temperature maintenance cost of the superconductors.

According to a particular aspect of the invention, the magnetic repulsion means comprise at least one permanent magnet. Thus, the repulsion forces generated between the superconducting modules and the frame are provided by magnetic repulsion means in the form of permanent magnets.

According to another particular aspect of the invention, said at least one permanent magnet is of formula Nd ₂ Fei ₄ B.

This type of permanent magnet is particularly well suited to new magnetic levitation transport technologies, such as magnetic levitation trains.

According to one particular characteristic, the magnetic repulsion means comprise an array of permanent magnets arranged in a configuration of the type

Halbach.

According to a particular characteristic, said at least one superconducting module comprises a cryostat itself comprising at least one superconducting element and a cryogenic fluid keeping said at least one superconductive element below a critical operating temperature.

The critical temperature depends on the nature of the superconductor used.

According to a particular aspect of the invention, said at least one superconducting element belongs to the group comprising:

a superconducting element of formula XBa ₂ Cu ₃ O ₇ , with X representing a rare earth of symbol Y, Nd, Sm, Gd or Eu;

a superconducting element of formula MgB ₂ ;

a superconducting element of formula Bi _a Ca Sr _c CU _d O _x ;

a superconducting element based on iron and whose critical temperature is greater than 30K.

This list is not exhaustive.

The critical temperature is 92 K for the superconductor YBCO, 39 K for the superconductor MgB2. An iron-based superconducting element that can be envisaged, for example, for the present invention is the compound (Ba, K) Fe ₂ As ₂ whose critical temperature is 38 K.

According to a particularly advantageous aspect, the superconducting module comprises a superposed first and second superconducting element and mechanically integral, said first superconducting element being associated with said magnetic guiding means and said second superconducting element being associated with said magnetic repulsion means.

According to a particular embodiment of system configuration, said magnetic guiding means and said magnetic repulsion means are of opposite polarities and are separated by a distance which is less than a critical spacing distance beyond which the force of magnetic repulsion produced by the magnetic guiding means and the magnetic repulsion means is no longer exerted between them.

Thus, thanks to this configuration, two magnetic devices of opposite polarity are obtained, the first being constituted by the superconducting element at the lower end of the modulus and the guiding means and the second being constituted by the superconducting element at the top. module and magnetic repulsion means secured to the chassis. When the distance between said magnetic guiding means and said magnetic repulsion means is less than the critical spacing distance, then an additional repulsion force is added due to the magnetic repulsion between the magnetic repulsion means and the magnetic resonance means. magnetic guidance of opposite polarities, amplifying the levitation forces acting on the frame of the veh icule. This favors the reinforcement of the levitation force with respect to the stability of the system.

According to an alternative embodiment of the system configuration, said magnetic guiding means and said magnetic repulsion means are of opposite polarities and are separated by a distance which is greater than a critical spacing distance beyond which the magnetic repulsion force produced by the magnetic guiding means and the magnetic repulsion means is no longer exerted between them.

When the distance between said magnetic guiding means and said magnetic repulsion means is greater than the critical spacing distance, the stability of the system is enhanced by decoupling the magnetic forces between the magnetic guiding means and the at least one a superconductive module and those exerted between it led at least one superconducting module and the chassis of the vehicle. This favors the stability of the system to reinforce the levitation force. According to another embodiment of the system configuration, said magnetic guiding means and said magnetic repulsion means are of the same polarity and are separated by a distance which is greater than a critical spacing distance beyond which the magnetic attraction force produced between the magnetic guiding means and the magnetic repulsion means is no longer exerted between them.

In this configuration, the system is operational and not function if the distance between led it means of magnetic guidance and said magnetic repulsion means is sufficiently large that the attractive force between these two magnetic elements is negligible in front of other magnetic forces.

According to one particular aspect of the invention, said magnetic guiding means is based on permanent magnets belonging to the group comprising:

permanent magnets of formula Nd ₂ Fei ₄ B;

permanent magnets based on cobalt and samarium.

This list is not exhaustive. Any other magnet having a coercive field and a remanent magnetization of the same order of magnitude as the magnets of formula Nd ₂ Fei ₄ B can be implemented.

According to a particular aspect of the invention, the permanent magnets of said magnetic guiding means are arranged according to a configuration of Halbach type.

It should be noted that other magnet configurations making it possible to generate a high field at the level of the superconductors can be envisaged without departing from the scope of the invention, as for example those represented in FIG. 2 of the article "Experiments in a Real Scale MagLev Vehicle Prototype by GGSotelo et al. published in Journal of Physics: Conference Series, volume 234, page 032054 in 2010 or those illustrated in figure 1 of the article Optimization of a superconducting linear Levitation System using a soft ferromagnet, published by S. Agramunt et al. in the journal "Physica C" (2013), volume 487, pages 11 to 15.

According to another particular aspect of the invention, said magnetic guidance means belongs to the group comprising:

at least one magnetic rail;

at least one magnetic path. 5. LIST OF FIGURES

Other features and advantages of the invention will appear on reading the following description, given by way of indicative and nonlimiting example, and the appended drawings, in which:

FIG. 1, already described in connection with the prior art, presents a simplified example of a magnetic levitation transport system known from the state of the art;

FIG. 2 represents a view of the transport system illustrated in FIG. 1 along the sectional plane A-A;

FIG. 3 represents the structure of the transport system illustrated in FIG.

1 according to the section plane B-B;

Figure 4 shows a sectional view of the structure of a magnetic levitation transport system according to a particular embodiment of the invention; Figure 5 shows a sectional view of the structure of a magnetic levitation transport system according to an alternative embodiment of the invention;

FIG. 6 illustrates an example of a network of permanent magnets distributed according to a configuration of the "Halbach" type, which can be implemented in the magnetic guiding means according to the invention;

FIG. 7 illustrates an example of a permanent magnet array distributed in a "Halbach" configuration, used as a magnetic repulsion means according to the invention.

6. DETAILED DESCRIPTION

In all the figures of this document, the elements and identical steps are designated by the same numerical reference.

FIG. 4 represents the structure of a magnetic levitation transport system according to a particular embodiment of the invention. This transport system more particularly comprises:

magnetic guiding means 11, composed for example of two magnetic rails; a vehicle movable in translation 12, such as a train for example, placed above the magnetic guiding means 11.

Each magnetic rail comprises an array of permanent magnets of formula Nd ₂ Fei ₄ B, arranged in a "Halbach" type configuration as shown in the diagram of FIG. 6.

Of course, this is a particular example and other types of permanent magnet performing the same function can be used without departing from the scope of the invention, such as samarium and cobalt magnets . More generally, each rail can be made from any permanent magnet-based material to the extent that the magnetic field created and its coercive field are sufficiently high. Those skilled in the art can choose the nature of the permanent magnets to achieve the above conditions, depending in particular on the mass of the vehicle to levitate and the nature of the superconductors with which the magnets will interact. Likewise, the configuration of the "Halbach" type is a particular non-limiting example. Other configurations of magnets can be used without departing from the scope of the invention, as for example those illustrated in the document titled "Optimization of a superconducting linear levitation system using a soft ferromagnet", published by S. Agramunt et al. . , in the journal "Physica C" (2013), volume 487, pages 11 to 15.

The vehicle 12 is provided with a chassis 13 and a plurality of magnetically levitated superconducting modules 14 located below the underside of the frame 13. The modules 14 are regularly distributed under the chassis and aligned in such a way that to face the magnetic guiding means 11. Each superconducting module 14 is composed of a cryostatic tank filled with a cryogenic fluid 17, such as liquid nitrogen for example (-196 ° C) or helium gaseous (at a few degrees or tens of degrees above its temperature of transition to the liquid state (-269 ° C)), in which is embedded a superconductor 16, for example of type YBa ₂ Cu ₃ O ₇ (also commonly called "YBCO"). The cryostatic reservoir and the cryogenic fluid ensure the maintenance of the superconductor 16 below a certain temperature, called the critical temperature Te, so that it develops its magnetic properties. For example, the critical temperature for the superconductor YBa ₂ Cu ₃ O ₇ is 92 K (ie -181 ° C). If this superconductor is cooled below this critical temperature, a magnetic repulsion force is exerted on the superconducting module 14, generating a levitation of the vehicle 12 above the magnetic guiding means 11, when the difference between the means 11 and superconducting module 14 is less than a critical spacing distance (threshold), beyond which the magnetic force no longer compensates the gravitational field acting on the vehicle. In other words, below this critical separation distance, the magnetic repulsion force produced compensates for the gravitational field acting on the vehicle 12. For example, when the superconductor 16 is cooled below the critical temperature Te, if the critical gap distance is 30 mm, a repulsive force will be produced if the distance between the guide means 11 and superconducting module 14 is less than 30 mm. In practice, the more the distance between the guide means 11 and the modu the su prconductor 14 decreases, the greater the magnetic repu lsion produ ity produces increased.

In other words, the guiding means 11 and the superconducting module 14 are configured to produce a repulsion force acting on the module 14 and which is sufficient for the vehicle 2, by transfer of force, to adopt a position levitating a few centimeters above the guiding means 11.

Other types of superconductor performing the same function can be envisaged without departing from the scope of the invention, for example: a superconductor of formula XBa ₂ Cu ₃ O ₇ with X representing a rare earth Y, Nd, Sm, Eu or Gd, a superconductor of the formula MgB ₂ , a superconductor of the formula Bi _a Ca Sr _c CU _d O _x whose superconducting properties appear for different ratios a: b: c: d: x (such as Bi ₂ Sr ₂ CaCu ₂ 08 and Bi ₂ Sr ₂ Ca ₂ Cu ₃ _{O 10 (} for example), a superconducting element of formula (Ba, K) Fe ₂ As ₂ . This list is not exhaustive. Those skilled in the art will adapt the nature of the permanent magnets as well as that of the superconductor (s) used so that, below the critical operating temperature, the repulsion force produced equilibrates the weight of the vehicle at a distance from the guiding means ensuring the operation of the transport system. Those skilled in the art will also adapt the cooling temperature according to the superconductor (s) used in the prconductor modules 14 so that it develops its magnetic properties in conjunction with the magnetic guiding means 11. The critical temperature, for example, is 92 K for the YBCO superconductor, 39 K for the MgB ₂ superconductor and 38 K for the (Ba, K) Fe ₂ As ₂ superconductor.

For each superconducting module 14, the transport system according to the invention further comprises magnetic repulsion means 15 between the underside of the frame 13 and the upper face of said superconducting module 14. These repulsion means 15 are mechanically fixed to the chassis and interact with said superconducting module 14 so that a magnetic repulsion force is generated on the repulsion means 15, causing the levitation of these latter, and thus of the vehicle 12, above said superconducting module 14, when the superconductor

16 is cooled below the critical temperature Te. Note that this effect is obtained when the distance between the superconducting module 14 and the magnetic repulsion means 15 is less than a critical spacing distance (threshold), beyond which the magnetic force is no longer sufficient to compensate. the gravitational field exerted on the vehicle 12. Otherwise, below this critical spacing distance, the magnetic repulsion force produced compensates for the gravitational field acting on the vehicle on the 12th.

In the example illustrated here, the magnetic repulsion means 15 consist of a network of permanent magnets, of formula Nd ₂ Fei ₄ B, distributed in a "Halbach" type configuration, as illustrated in FIG. 7. Of course, the invention is not limited to this particular example, but can be applied to any type of magnetic repulsion means whose function is to produce a magnetic repulsion force on a superconducting modu, without leaving the frame of the invention. One could consider for example the use of a single permanent magnet block or another assembly of permanent magnets performing the function of magnetic repulsion means according to the invention.

Those skilled in the art will adapt the nature of the permanent magnets used as magnetic repulsion means according to the invention so that the repulsive force produced balances the weight of the vehicle at a distance of the superconducting module ensuring operation and stability of the transport system.

Any material based on permanent magnets can be used to create a high remanent field, ie equal to or greater than 0.5 T, and having a high coercive field, i.e. equal to or greater than 1000 kA / m. For example, an array of permanent magnets whose chemical formula includes samarium and cobalt and whose remanent magnetic field can reach 1.1 T and the coercive force of 2000 kA / m can be considered.

In this configuration, the veh icule 12 is found in magnetic levitation above the superconducting modu 14, which itself is levitated above the magnetic guiding means 11. The invention therefore proposes a double magnetic suspension system, A magnetic suspension is present on either side of the superconducting module 14. Thus, unlike conventional levitation transport systems, the superconducting modules are no longer mechanically linked to the chassis, which makes it possible to generate more repulsive forces. while preserving the temperature maintenance cost of the superconductors (since the thermal losses are considerably reduced).

The inventors have discovered that, depending on the structure and the dimensions of the magnetic repulsion means 15, there is a range of distances between the magnetic repulsion means 15 and the rail 11 for which the system as a whole is stable even if the magnetic repulsion means 15 and the rail 11 have opposite polarities. By way of example, if the magnetic repulsion means 15 are identical to those of magnetic guidance 11, the stability is obtained if the distance between the magnetic repulsion means 15 and the superconducting module 14 is equal to or close to that between the rail 11 and the superconducting module 14.

The transport system according to the invention may also comprise elastic damping means (not shown in the figures) placed on the magnetic repulsion means 15 and the frame 13, the role of which would be to absorb at least partially the mechanical stresses acting on the magnetic repulsion means 15.

Those skilled in the art are able to define the magnetic repulsion forces respectively between the guide means and the superconducting module, and between the prconductor module and the repulsion device, necessary for the levitation of the vehicle. FIG. 5 represents a magnetic levitation transport system according to an alternative embodiment of the invention.

In contrast to the system shown in FIG. 4, the superconducting module 140 of the vehicle 120 illustrated in FIG. 5 comprises two superposed and mechanically integral superconducting blocks 141 and 142. The principle here is to associate the superconductor

141 disposed in the upper part of the module 140 with the magnetic repulsion means 15 attached to the frame 13 and the superconductor 142 disposed in the lower part of the module 140 with the magnetic guide means 11, so as to form a double magnetic suspension system according to the invention.

In the case of opposite polarities between the guiding means and the repulsion device attached to the frame, as illustrated in FIG. 5 (faces of opposite polarities facing south), a complementary repulsion force can be exerted between said means. 11 and said repulsion means 15, depending on the distance between them.

For this complementary force to be created, the distance between the magnetic repulsion means 15 and the rail 11 must be less than a critical spacing distance (threshold) beyond which the magnetic repulsion forces produced by means of magnetic guidance 11 and the magnetic repulsion means 15 no longer interact with one another or are negligible compared to other magnetic forces acting in the system. Below this critical spacing distance, the magnetic forces for levitating the vehicle 120 are reinforced by the repetitive interaction between magnets.

Conversely, if the distance between the magnetic repulsion means 15 and the superconducting rail 11 is equal to or greater than the critical spacing distance, the interaction between the repulsion means 15 and the guide means 11 which tends to destabilize the system becomes negligible in the face of other magnetic forces

negligible magnet-magnet interaction and the stabilization of the system is improved.

Thus, this variant makes it possible to obtain two magnetic devices of opposite polarities (the first consisting of the superconducting element at the lower end of the module and the guiding means and the second being constituted by the superconducting element in the upper part of the module and magnetic repulsion means secured to the frame) providing the possibility of amplifying the levitation forces necessary to levitate the vehicle above the guide means while maintaining a satisfactory stability of the system as a whole.

Those skilled in the art will adapt the distance between the two superconductors 141 and 142, as well as the nature, shape and arrangement of the magnetic materials used in the various elements of the system, so as to find the best compromise between the reinforcement of the the levitation force of the veh icule and the maintenance of a satisfactory stability of the system as a whole (the more this distance decreases, the more the levitation force is reinforced and the less the system is stable, and the more this distance increases, the more stable the system is preferred and less levitation force is reinforced).

According to an alternative embodiment, the magnetic rail and the magnetic repulsion means may be of the same polarity. In this case, they must be separated by a distance which is greater than a critical spacing distance beyond which the magnetic attraction force produced between the magnetic rail and the magnetic repulsion means is no longer exerted. between them. In this configuration, the system is operational and operates if the distance between said magnetic guiding means and said magnetic repulsion means is sufficiently large so that the attractive force between these two elements is negligible compared to the other magnetic forces.

Claims

A magnetic levitation transport system comprising:

magnetic guiding means (11);

a vehicle movable in translation (12) placed above said magnetic guiding means, the vehicle being provided with a frame (13);

a set of magnetic levitation superconducting modules (14) located below the underside of the vehicle frame and aligned to face said magnetic guiding means so as to levitate above said magnetic guiding means;

for at least one superconducting module, magnetic repulsion means (15) placed between the lower face of the chassis and the upper face of at least one superconducting module, said magnetic repulsion means being configured on the one hand for be mechanically secured to the underside of the chassis and on the other hand so as to create a magnetic repulsion force to put the said magnetic repulsion means integral with the chassis levitated above said at least one superconducting module,

the transport system being characterized in that said at least one superconducting module comprises a superconducting first (142) and second (141) superconducting element mechanically integral, said first superconducting element being associated with said magnetic guiding means (11) and said second superconducting element being associated with said magnetic repulse means (15).

2. System according to claim 1, wherein the magnetic repulsion means (15) comprise at least one permanent magnet.

3. System according to revendication 2, wherein said at least one permanent magnet is of formula Nd ₂ Fei ₄ B.

4. System according to any one of claims 1 to 3, wherein the magnetic repulsion means (15) comprise an array of permanent magnets arranged in a Halbach-type configuration.

5. System according to any one of claims 1 to 4, wherein said at least one superconducting module comprises a read cryostat itself including at least one superconducting element and a cryogenic fluid maintaining said at least one superconducting element underneath. a critical temperature of operation.

The system of claim 5, wherein said at least one superconducting element belongs to the group comprising:

praconducteu a known element r of the formu Xba ₂ Cu ₃ 07 where X represents a rare earth symbol Y, Nd, Sm, Eu or Gd;

a superconducting element of formula MgB ₂ ;

a superconducting element of formula Bi _a Ca Sr _c CU _d O _x ;

a superconducting element based on iron.

The system according to any one of claims 1 to 6, wherein said magnetic guiding means (11) and said magnetic repulsive means (15) are of opposite polarities and are separated by a distance which is less than a distance. of critical spacing beyond which the magnetic repulsion force produced by the magnetic guiding means (11) and the magnetic repulsion means (15) is no longer exerted between them.

The system of any of claims 1 to 6, wherein said magnetic guiding means (11) and said magnetic repulsive means (15) are of opposite polarities and are separated by a distance which is greater than a critical spacing distance beyond which the magnetic repulsion force produced by the magnetic guiding means (11) and the magnetic repulsion means (15) is no longer exerted between them.

9. System according to any one of claims 1 to 6, wherein said magnetic guiding means (11) and said magnetic repulsion means (15) are of the same polarity and are separated by a distance which is greater than one critical distance apart beyond which the magnetic attraction force produced between the magnetic guiding means (11) and the magnetic repulsion means (15) is no longer exerted between them.

10. System according to any one of claims 1 to 9, wherein said magnetic guiding means (11) is based on permanent magnets belonging to the group comprising:

permanent magnets of formula Nd ₂ Fei ₄ B;

permanent magnets based on cobalt and samarium.

11. System according to any one of claims 1 to 10, the permanent magnets of said magnetic guiding means (11) are arranged in a Halbach-type configuration.

12. System according to any one of claims 1 to 11, wherein said magnetic guiding means belongs to the group comprising:

at least one magnetic rail;

at least one magnetic path.