JP2905508B2 - Magnetic levitation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic levitation device such as an XY stage levitation device and a bearing device. More specifically, the present invention relates to a magnetic levitation device comprising a superconductor and a plurality of magnets, which enables good and stable magnetic levitation.

(Background Art) With the development of precision machining technology in recent years, the necessity of guide means for precise positioning devices and high-precision, highly rigid bearings has been increasing. As a technology for this purpose, the Meissner effect has been used. Non-contact magnetic levitation devices such as magnetic levitation XY stage devices and magnetic levitation bearing devices have been considered.

In recent years, high-temperature superconductors have been discovered and this magnetic levitation can be realized by the Meissner effect under cooling conditions using inexpensive liquid nitrogen. Various proposals have been made to configure a magnetic levitation device by combining the above.

However, the magnetic levitation support devices considered so far have not been able to obtain a stable levitation performance that can be put to practical use. In addition, it was not clear how to design and configure the magnetic properties, shapes, sizes, etc. of the superconductors and magnets to be used by specific means and methods.

(Object of the Invention) The present invention has been made in view of the above circumstances, and solves the drawbacks of the prior art to provide a good and stable magnetic levitation characteristic to an XY stage levitation device or a magnetic bearing device. It is an object of the present invention to provide a new magnetic levitation device which can be easily designed and manufactured, and a method of manufacturing the same.

(Disclosure of the Invention) In order to achieve the above object, the present invention comprises a superconductor and a plurality of magnets, and N poles and S poles of the plurality of magnets are alternately arranged to face the superconductor. A magnetic levitation device, wherein the magnets are arranged in contact with each other, and have a width at which the supporting rigidity has a maximum value according to a predetermined magnetization strength and a predetermined repulsive levitation force and levitation distance. A magnetic levitation device is provided.

Further, as a specific embodiment, there is provided an XY stage levitation apparatus characterized in that one of the superconductor and the plurality of magnets forms an XY stage, and the other forms a stage base.

Further, the present invention specifically provides a bearing device in which one of a superconductor and a plurality of magnets forms a shaft, and the other forms a bearing.

Furthermore, in the above-mentioned XY stage, it is provided as a mode that each magnet has a thickness that does not cause demagnetization (claim 3).
Each magnet is arranged in contact with each other along the circumferential direction,
N-poles and S-poles of adjacent magnets are alternately magnetized along the circumferential direction so as to face the superconductor (Claim 5),
Each magnet is disposed in contact with each other along the axial direction,
N poles and S poles of adjacent magnets are alternately arranged along the axial direction so as to face the superconductor (claim 6),
Each magnet is arranged in contact with each other along the circumferential direction,
The same polarity of the N pole or the S pole of each adjacent magnet is arranged facing the magnet (Claim 7), and each magnet has a thickness that does not cause demagnetization (Claim 7). 8)
Each magnet has a magnet arrangement angle at which the bearing stiffness has a maximum value according to a desired magnitude of shaft displacement, a predetermined shaft radius and a bearing inner radius (claim 9). Is also provided as an embodiment thereof.

That is, according to the present invention, when the N pole and the S pole of a plurality of magnets are alternately arranged so as to face the superconductor, the repulsive levitation force between the superconductor and the magnet is related to the flying distance. Further, the present invention has been completed by finding that the width of the magnet, the thickness of the magnet, and the strength of the magnetization have a specific relationship. It is based on the knowledge that the width of the magnet, the thickness of the magnet, and the strength of the magnetization can be determined according to the required predetermined repulsive levitation force or levitation distance.

FIG. 1 is a schematic view showing an embodiment in which the magnetic levitation device of the present invention is embodied as an XY stage levitation device.

The XY stage levitation apparatus shown in FIG. 1 includes an XY stage (1) made of a superconductor and a stage base (2) provided with a plurality of magnets. In this case, the type of the superconductor constituting the XY stage (1) is not particularly limited, and a Y-Ba-Cu-oxygen system, a Bi-Ca-Sr-Cu-oxygen system, and various other high-temperature superconductors are used. can do. The type of the plurality of magnets is not particularly limited, and for example, a rare earth magnet or the like can be used.

In the example of FIG. 1, each of the plurality of magnets has a magnetization intensity I, and is formed of a rectangular parallelepiped having a width d and a thickness t.
They are arranged in contact with each other. The N pole and the S pole are alternately arranged so as to face the superconductor XY stage (1). The depth (Y-axis direction) of the stage base (2) is
In this example, the length is sufficiently longer than the depth of the XY stage (1). Of course, this is not necessary depending on the shape. Further, the XY stage (1) is designed to float at a position at a floating distance z from the surface of the stage base (2).

FIG. 2 illustrates a generated magnetic field in the XY stage levitation apparatus. As shown in FIG. 2, when a plurality of magnets of the stage base (2) are arranged so that their N poles and S poles are alternately opposed to the superconductor of the XY stage (1), the magnets emerge from the N pole. The line of magnetic force enters the adjacent south pole. As a result, a strong magnetic field can be easily formed, the lines of magnetic force exist only on the surface of the magnet, and the magnetic field gradient can be increased. A large repulsive levitation force F is obtained on the magnet surface.

The magnets may be arranged individually, or may be manufactured and arranged by writing as a single rubber magnet with an alternating magnetic field.

FIG. 3 is a schematic view showing an embodiment in which the magnetic levitation device of the present invention is embodied as a bearing device.

This example of a bearing device has a shaft (3) made of a superconductor and a bearing (4) provided with a plurality of magnets. In this case, each of the plurality of magnets has a magnetization intensity I and a width d.
(I.e. the angle θ with respect to the center (O ₄₎ of the bearing (4)), consists magnet thickness t, along with being provided in contact with each other, the axis of the N and S poles alternately (3) Are arranged so as to oppose to each other. In the example shown in FIG. 3, more specifically, the respective magnets are disposed in contact with each other along the circumferential direction, and the north pole and the south pole of the singing magnets are alternately arranged along the circumferential direction. Magnets are arranged facing the superconductor axis (3).
The shaft (3) has a radius R ₃ , the bearing (4) has a radius R ₄ ,
The shaft (3) floats in the bearing (4). Although the shaft (3) has a cylindrical shape, it may have a cylindrical shape.

FIG. 4 illustrates the magnetic field of the bearing device.
Similar to the magnetic field distribution of the XY stage levitation device shown in FIG. 2, the magnetic field lines coming out of the N pole enter the adjacent S pole. A large repulsive levitation force F is obtained on the magnet surface.

In the present invention, the repulsive levitation force F formed by arranging a plurality of such magnets so as to be in contact with each other has a levitation distance z, a magnet width d, and a magnet width d as illustrated in FIGS. Are determined in a preferable range based on the specific relationship with the thickness t and the magnetization intensity I. Specifically, in the present invention, each magnet disposed in contact with each other has a predetermined magnetization strength and a width at which the supporting rigidity has a maximum value in accordance with a predetermined repulsive levitation force and a levitation distance. It is assumed. It is also a preferable embodiment that each magnet has a thickness that does not cause demagnetization.

Note that these relationships can be calculated as follows. That is, for example, for the XY stage levitation apparatus shown in FIG. 1, as an example, the thickness t of each rectangular solid magnet
Is assumed to be 5 mm and the magnetization intensity I is 0.27 Wb / m ² ,
Regardless of the thickness of the superconductor of the stage (1),
When a stage base (2 ') (shown by a dotted line in FIG. 1) having a mirror image equivalent to a magnet of the stage base (2) is formed at a distance twice the flying distance z from the surface of the stage base (2). Model. Then, the strength of the magnetic field generated by one magnet forming the stage base (2) at an arbitrary point is calculated, and based on the calculated strength, the strength of the magnetic field exerted by all the magnets forming the stage base (2) on the arbitrary point is calculated. The strength is determined, and the repulsive levitation force applied to the minute volume of the XY stage (1) is calculated in consideration of the strength of the magnetic field generated by the magnet of the mirror-based stage base (2 '). Then, this value is integrated over the entire area of the XY stage (1) to obtain the repulsive levitation force F as a whole. The calculation of the repulsive levitation force F can be similarly performed for an XY stage levitation apparatus in which the XY stage (1) is configured by a plurality of magnets and the stage base (2) is configured by a superconductor.

Similarly, in the bearing device of FIG. 3, it is considered that a mirror image equivalent to the magnet of the bearing (4) is formed, and the repulsion by all the magnets constituting the bearing (4) and the mirror image magnet is performed. The floating force F can be calculated. The calculation of the repulsive levitation force F can be similarly performed for a bearing device in which the shaft (3) is composed of a plurality of magnets and the bearing (4) is composed of a superconductor.

5 to 8 show various relationships calculated and obtained as described above for the XY stage levitation apparatus in FIG. Fig. 5 shows the repulsive levitation force F (Kgf /
m ² ) and the flying distance z (mm),
This is for the case of 16 mm. As a result, when the flying distance z is about 1 mm or more, the repulsive levitation force F sharply decreases as the flying distance z increases, but this tendency is more remarkable as the magnet width d is smaller, and is most significant when the magnet width d is 2 mm. It turns out to be remarkable. On the other hand, when the width d of the magnet is 16 mm, a relatively large repulsive levitation force F is obtained even when the flying distance is 2 mm or more.
It can be seen that can be maintained. This is because the repulsive levitation force F depends on the magnitude of the magnetic field gradient of the leakage magnetic field of the magnet of the stage base (2). This magnetic field gradient is particularly large when the flying distance z is small, about 1 mm, and the magnet width d is 2 mm. If so, it is considered that the magnetic field gradient is steep. Also, the width d of the magnet is
It is considered that the reason why the repulsion levitation force F decreases relatively slowly when the length is 16 mm is that the magnetic field gradient of the leakage magnetic field is gradual over a considerable range of the levitation distance z.

FIG. 6 shows the support rigidity K (Kgf / m ² / mm) and the flying distance z (m
(m) is shown for the case where the width d of the magnet is 2 to 16 mm. The support stiffness K is obtained by differentiating the repulsive levitation force F in FIG. 5 with the levitation distance z. According to FIG. 6, the supporting rigidity K decreases as the flying distance z increases, but this tendency becomes more significant as the magnet width d is smaller.
It can be seen that in a range smaller than about 1 mm, the support rigidity K when the magnet width d is 16 mm is significantly smaller than the support rigidity K when the magnet width d is 2 to 5 mm. This indicates that when the flying distance z is smaller than 1 mm and the magnet width d is 16 mm, the restoring force is less likely to act on the XY stage (1).

FIG. 7 shows the supporting rigidity K (Kgf / m ² / mm) and the magnet width d (m
(m) is shown in the case where the flying distance z is 0.5 to 3 mm. Flying distance z is 0.5mm or 1.0mm
It can be seen that when the width d of the magnet is 3 mm or 5 mm, a clear maximum value appears in the support rigidity K. Thus, it is understood that it is preferable to set the width d of the magnet so that the support rigidity K shows the maximum value in accordance with the required predetermined flying distance z. Further, it is found that if the width d of the magnet is smaller than 2 mm, the supporting rigidity K rapidly decreases, which is not preferable. This is considered to be because the range of the leakage magnetic field from the magnet is reduced when the width of the magnet is small.

FIG. 8 shows the repulsive levitation force F (Kgf / m ² ) and the thickness t of the magnet.
(Mm) when the width d of the magnet is 2 to 8 mm. This relationship is based on the flying distance z
Is set to 1 mm. When the width d of the magnet is 2 to 5 mm, the repulsion levitation force F shows a substantially constant value by making the thickness t of the magnet larger than about 5 mm.
When the width d of the magnet is 8 mm, the repulsive levitation force F is not constant even if the thickness t of the magnet is larger than 7 mm. Thereby, in order to obtain a stable repulsive levitation force F, the width d of the magnet is required.
It is understood that it is preferable to make the thickness t of the magnet sufficiently large. This is considered to be because the effect from both magnetic poles of the magnet is less likely to be exerted by sufficiently increasing the thickness t of the magnet, and the repulsive levitation force F is saturated. That is, the thickness t of the magnet is preferably set to a size that does not cause demagnetization.

As described above, in the XY stage levitation apparatus of the present invention illustrated in FIG. 1, each magnet disposed so as to be in contact with each other has a predetermined magnetization strength I, a predetermined repulsive levitation force F, and a levitation distance. The width d at which the support rigidity K has a maximum value according to z
It is preferable that each magnet has a thickness t that does not cause demagnetization.

9 to 11 show various relationships calculated for the bearing device of FIG. Fig. 9 shows
The relationship between the bearing stiffness K (Kgf / mm) and the axial displacement x (mm) (bearing (shift distance of the center O ₃ of the shaft (3) from the center O ₄ of 4)), a magnet arrangement angle theta 3 This is shown for the case of up to 30 deg. Note that this relationship is based on the radius R ₃ of the axis (3).
The 14.5 mm, and calculates the inner radius R ₄ of the bearing (4) as 15 mm. For any of the magnet arrangement angles θ of 3 to 30 deg., The bearing rigidity K increases as the axial displacement x increases. This is considered to be because when the axial displacement x increases, the shaft (3) formed of the superconductor approaches the bearing (4) formed of the magnet, and the repulsive levitation force increases. Also, the smaller the magnet arrangement angle θ is, the more the bearing rigidity K tends to increase when the axial displacement x is increased. As a result, the magnet arrangement angle θ
It can be understood that when the value of is reduced, a strong repulsive levitation force is applied when the shaft (3) is brought closer to the bearing (4).

FIG. 10 shows the relationship between the bearing stiffness K (Kgf / mm) and the magnet arrangement angle θ when the axial displacement x is 0.1 to 0.5 mm. As the axial displacement x increases, the bearing rigidity K increases. This is considered to be because if the axial displacement x is large, the gap between the shaft (3) and the bearing (4) becomes small, and the magnetic field gradient becomes large. Also, set the axial displacement x to 0.
When it is 1 to 0.4 mm, a maximum value appears in the bearing rigidity K, and the magnet arrangement angle θ that gives this maximum value decreases as the axial displacement x increases. Thus, it is understood that the magnet arrangement angle θ is preferably set so as to give the maximum value to the bearing rigidity K in accordance with the required predetermined axial displacement x. Here, the magnet arrangement angle θ corresponds to the magnet width d, the axial displacement x corresponds to the flying distance z, and the bearing rigidity K corresponds to the support rigidity K. Note that the bearing rigidity refers to the support rigidity due to the interaction between the shaft and the support bearing.

FIG. 11, the repulsive levitation force F and (Kgf) the relationship between the magnet arrangement angle theta, the inner radius R ₄ of the bearing (4) is fixed to 15 mm, the radius R ₃ of the shaft (3) 14.5～14.9Mm FIG. This relationship is based on a bearing length of 50m.
m, and the axial displacement x was calculated as 0.05 mm. Repulsive levitation force F is greater the larger the radius R ₃ of the shaft. Further, except when the radius R ₃ of the shaft and 14.9 mm, the radius R ₃ of each axis there is a magnet arrangement angle θ which gives the maximum value for the resilience levitation force F, the radius of this angle θ is axial It decreases as R ₃ increases. This gap between the radius R ₃ of the shaft is greater and the shaft (3) and bearing (4) is reduced, is considered because the field gradient increases. Thus, if the radius R ₃ of the shaft and the inner radius R _{4 of the} bearing are determined, the magnet arrangement angle θ
It is understood that it is preferable to set the maximum value of the bearing rigidity K in accordance with the magnitude of the radius.

As described above, in the bearing device of the present invention illustrated in FIGS. 3 and 4, each magnet disposed so as to be in contact with each other along the circumferential direction has a desired axial displacement x and a predetermined axial displacement. It is preferable to have a magnet arrangement angle θ at which the bearing rigidity K has a maximum value according to the size of the radius R ₃ and the inner radius R ₄ of the bearing. It is also preferable that each magnet has a thickness t that does not cause demagnetization, as in the case of the XY stage levitation apparatus described above, in order to obtain a stable repulsive levitation force F.

As described above, the magnetism intensity I of the magnet to be used is set, and the relation between the repulsive levitation force F and the levitation distance z, the width d of the magnet, the thickness t, etc. is calculated, and the width of the magnet is determined based on the calculated value. d
(Or angle θ) and thickness t. For example, in the case of manufacturing an XY stage levitation device, a required repulsive levitation force F is determined according to the load weight on the XY stage.
And the magnetization intensity I can be determined. The thickness t of the magnet is set to a value sufficiently larger than the width d of the magnet. on the other hand,
In the case of manufacturing a bearing device, both radii are determined to be suitable sizes based on the relationship calculated as described above within a range allowed by design in terms of the radius of the shaft and the inner radius of the bearing, and The magnet arrangement angle θ and the magnetization intensity I can be determined.

In the XY stage levitation device and bearing device manufactured in this manner, precise magnetic levitation that maintains the levitation distance z or the axial displacement x at 1 μm or less is also possible.

Further, the bearing device may be configured as illustrated in FIGS. 12 (a) and (b) or configured as illustrated in FIGS. 13 (a) and (b).

In the bearing device illustrated in FIG. 12 (a), the bearing (12)
Has the same configuration as the bearing (12) in the bearing device exemplified in FIGS. 3 and 4 described above, that is, each magnet is disposed in contact with each other along the circumferential direction, and the N pole of the adjacent magnet is The structure is such that the S poles are arranged magnets alternately along the circumferential direction so as to face the superconductor axis (11), but the superconductor axis (11) is longer than the bearing (12). . In this case, the shaft (11) moves smoothly in the longitudinal direction and becomes smooth.

In the bearing device illustrated in FIG. 12 (b), the bearing (12)
Are arranged such that the respective magnets are in contact with each other along the axial direction, and the north and south poles of adjacent magnets are alternately arranged along the axial direction so as to face the axis (11) of the superconductor. It is configured. In this case, the shaft (11) moves well in the rotational direction,
Become smooth.

In the bearing device illustrated in FIGS. 13 (a) and (b),
The bearing (12) is composed of a superconductor and the shaft (11) is composed of a plurality of magnets. In each case, the shaft (11) is a bearing (12) in the bearing device of FIGS. 12 (a) and (b). Has the same configuration as the magnet configuration.

In other words, in FIG. 13 (a), the shaft (11) is such that the magnets are disposed in contact with each other along the circumferential direction, and the N pole and S pole of the adjacent magnet alternate in the circumferential direction. The magnet is arranged to face the superconductor. In the example of FIG. 13 (b), the axis (11) is such that the magnets are disposed in contact with each other along the axial direction, and the north pole and the south pole of the adjacent magnets are superconductive with each other along the axial direction. The magnet is arranged to face the body.

In the case where the plurality of magnets have the configuration shown in FIG. 12 (b) and FIG. 13 (b), the width and thickness of each magnet refer to the width in the axial direction and the thickness in the radial direction, respectively. . In other words, in each magnet, the axial width is assumed to be a size at which the supporting rigidity becomes the maximum value in accordance with the predetermined repulsive levitation force and the levitation distance, and the radial thickness is set to a size that does not demagnetize. It is preferred that it is.

In addition to the magnet configuration described above, the shaft (11) or bearing (1
The plurality of magnets constituting 2) may have a structure as exemplified in FIG. That is, the magnets are arranged in contact with each other along the circumferential direction, and the same polarity of the N pole or the S pole of each adjacent magnet is arranged to face each other. It is preferable that each magnet has a magnet arrangement angle at which the bearing rigidity has a maximum value in accordance with the desired magnitude of the axial displacement, the radius of the predetermined shaft, and the magnitude of the inner radius of the bearing.

In the bearing device of each of the above examples, the shaft and the bearing are both cylindrical, but the shaft and the bearing may be polygonal.

Hereinafter, the present invention will be specifically described based on examples.

Embodiment 1 In a bearing device as shown in FIG. 3, YB is used as the shaft (3).
The CO-based high temperature superconductors radius R ₃ is used which 3.5 mm, the weight is formed into a cylindrical 2.5g, also as a bearing (4) inside radius R ₄ has decided to use a 6 mm. The magnet arrangement angle θ was 45 deg.

This bearing device was placed in a glass dewar containing liquid nitrogen (temperature 77 K), cooled to below the critical temperature of the high-temperature superconductor, and then the operation of this device was observed. It was confirmed that the bearing (4) was stably present in the bearing (4), and the shaft (3) stably floated at the center of the bearing (4) even when the bearing (4) was rotated or moved.

Example 2 When the radius R ₃ of the shaft (3) was 4.75 mm and the weight was 3.5 g, a suitable value of the magnet arrangement angle θ was obtained in the same manner as in Example 1, and the operation of the bearing device was observed. It was confirmed that the shaft (3) was stably present at the center of the bearing (4).

(Effects of the Invention) According to the present invention, it is possible to efficiently manufacture magnetic levitation devices such as XY stage levitation devices and bearing devices having stable magnetic levitation performance.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an XY stage levitation apparatus of the present invention. FIG. 2 is a magnetic field distribution diagram of the XY stage levitation apparatus shown in FIG. FIG. 3 is a schematic perspective view of the bearing device of the present invention. FIG. 4 is a magnetic field distribution diagram of the bearing device shown in FIG. FIG. 5 is a correlation diagram between the repulsive levitation force F of the XY stage levitation device and the levitation distance z. FIG. 6 is a correlation diagram between the support rigidity K of the XY stage levitation device and the levitation distance z. FIG. 7 is a correlation diagram between the support rigidity K of the XY stage levitation device and the magnet width d. FIG. 8 is a correlation diagram between the repulsive levitation force F of the XY stage levitation device and the thickness t of the magnet. FIG. 9 is a correlation diagram between the bearing rigidity K of the bearing device and the axial displacement x. FIG. 10 is a correlation diagram between the bearing rigidity K of the bearing device and the magnet arrangement angle θ. FIG. 11 is a correlation diagram between the repulsive levitation force F of the bearing device and the magnet arrangement angle θ. 12 (a) and 12 (b) are perspective views each showing another example of the bearing device. 13 (a) and 13 (b) are perspective views each showing an example of a bearing device. FIG. 14 is a front view illustrating still another magnet arrangement. (1) XY stage (2) Stage base (3) Shaft (4) Bearing

Claims (9)

(57) [Claims] 1. A magnetic levitation device comprising a superconductor and a plurality of magnets, wherein N and S poles of the plurality of magnets are alternately arranged to face the superconductor with magnets. A magnetic levitation device, which is disposed in contact with and has a predetermined magnetization strength and a width at which the supporting rigidity has a maximum value according to a predetermined repulsive levitation force and a levitation distance. . 2. The levitation apparatus according to claim 1, wherein one of the superconductor and the plurality of magnets forms an XY stage, and the other forms a stage base. . 3. The XY stage levitation apparatus according to claim 2, wherein each magnet has a thickness that does not cause demagnetization. 4. The magnetic levitation device according to claim 1, wherein one of the superconductor and the plurality of magnets forms a shaft, and the other forms a bearing. 5. The magnets are arranged in contact with each other along the circumferential direction, and N poles and S poles of adjacent magnets are alternately arranged along the circumferential direction so as to face the superconductor. The bearing device according to claim 4. 6. The magnets are arranged in contact with each other along the axial direction, and N poles and S poles of adjacent magnets are alternately arranged along the axial direction so as to face the superconductor. The bearing device according to claim 4. 7. The magnet according to claim 4, wherein the magnets are arranged so as to be in contact with each other along the circumferential direction, and the same polarity of the N pole or S pole of each adjacent magnet is arranged facing each other. Bearing device. 8. The bearing device according to claim 5, wherein each magnet has a thickness that does not cause demagnetization. 9. Each magnet has a magnet arrangement angle at which a bearing rigidity or a shaft rigidity has a maximum value in accordance with a desired magnitude of a shaft displacement and a predetermined shaft radius and a bearing inner radius. The bearing device according to (5) or (7).