JPH0752691B2 - Magnetic levitation device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic levitation device, and more particularly, to a self-controlled magnetic levitation device capable of supporting an object in a contactless levitating state by utilizing a magnetic field. .

[Conventional technology]

When using a magnetic field to levitate an object without contact, if you try to attract only with a magnet, the shorter the distance between the magnetic pole and the levitation body, the stronger the attractive force becomes. Will come into contact with. So, to prevent this,
Conventionally, a distance sensor measures a clearance between an object and a magnetic pole, and a control circuit is used to adjust an electric current of an electromagnet so that the object floats at a constant distance from the magnetic pole. (See Gakudensha's "Magnetic Magnetic Engineering" (Kazuto Yamada et al., P. 153)) Also, by using the perfect diamagnetic effect of superconductors, the magnetic levitation can be performed without the external control by utilizing the repulsive force of the magnetic field. The method of making it known is also known. (See “Low Temperature Technology” by The University of Tokyo Press (Shunichi Kobayashi) P.78) [Problems to be solved by the invention] However, in the conventional control type magnetic levitation device described above, control by an external circuit is complicated. It is expensive. In addition, when used in a vacuum device, a port is required for a sensor lead wire and an electromagnet lead wire. Also, when trying to apply to a mobile device, these lead wires get in the way.

On the other hand, the superconducting magnetic levitation device does not require a control circuit, but requires a cooling device using liquid helium in order to keep it at a low temperature, which makes it expensive and difficult to handle.

If so, whether repulsive magnetic levitation by a diamagnetic material at room temperature is possible is that x of magnetic susceptibility (susceptibility) that shows diamagnetism even in bismuth or graphite, which has the strongest room temperature diamagnetism.
Is about x >> − 10 ^−4, which is about 1 / 10,000 compared to the magnetic susceptibility x = −1 of the superconductor. Therefore, the levitation force is too small for the repulsive magnetic levitation with only the room temperature diamagnetic material.

In view of the above problems, an object of the present invention is to essentially eliminate the need for an electrical control circuit, to obtain a stable levitation force, and to achieve magnetic levitation without the need for lead wires. To provide a levitation device.

(Means for Solving the Problems) In order to achieve such an object, the present invention provides a levitation body and a means for levitating the levitation body with a ferromagnetic material and a diamagnetic material, On the other hand, a magnet having a magnetic pole capable of magnetic saturation in the high magnetic field saturation region is provided on the other hand, and the ferromagnetic substance is attracted in the magnetic saturation state by the magnet in the saturation region. The levitation body is kept in a levitating state at a stable point where the self-weight of the levitation body and the repulsive force that repels the diamagnetic body are balanced.

[Work]

According to the magnetic levitation device of the present invention, an attractive force and a repulsive force are generated between the ferromagnetic material and the diamagnetic material of the levitation body and the magnet that is provided to levitate the levitation body and that generates a strong magnetic field. Therefore, in the saturation region of the ferromagnet, the magnetic field gradient by the magnet, the volume of the ferromagnet vs. The levitation body can be kept in a levitating state by appropriately setting its own weight.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, which is an example in which a set of a diamagnetic material and a ferromagnetic material are arranged in combination on the side of a floating body. Here, 1 is a magnet that generates a magnetic field for levitating the levitation body, and the magnet 1 may be either a permanent magnet or an electromagnet. Reference numeral 2 denotes the magnetic pole, which can appropriately adjust the gradient of the magnetic field generated depending on the configuration of the magnetic pole 2. The magnet 1 is supported by a support (not shown).

On the other hand, 3 is a ferromagnetic material provided on the floating body side, and as the ferromagnetic material 3, a metal such as soft iron or cobalt or a ferromagnetic alloy such as permalloy or supermalloy is used. That is, since the ferromagnetic material 3 is attracted to the opposing magnetic poles 2 by the magnetic field of the magnet 1, the attraction force generates a levitation force on the side of the levitation body 4. In this case, the ferromagnetic material 3 is When the magnetic pole 2 is approached to some extent, it is magnetically saturated, and when the magnetic pole 2 is approached beyond that, the attractive force does not increase.

Reference numeral 5 is a diamagnetic material arranged around the ferromagnetic material 3. As the diamagnetic material 5, bismuth, graphite, phosphorus or niobium, Nb ₃ Sn, Nb-Ti, or a special organic compound is used. You can One of the diamagnetic members 5 produces a repulsive force by the magnet 1 although it is weak, and this repulsive force increases as the diamagnetic member 5 approaches the opposing magnetic pole 2, and becomes stronger at a proximity point which will be described later. The increase in the attractive force of the magnetic body 3 is canceled out. Therefore, when the resultant force of the repulsive force of the diamagnetic body 5 and the own weight of the levitation body 4 becomes equal to the attractive force of the ferromagnetic body 3 in the saturated magnetization state, the levitation body 4 is stably levitated.

In addition, in order to perform the floating operation of the levitation body 4 as described above with one magnet 1 as in this example, the ferromagnetic material 3 is used.
The diamagnetic material 5 and the diamagnetic material 5 may be laminated, or both particles may be mixed and molded, or one of them may be embedded in the other or bonded to each other.

FIG. 2 shows another embodiment of the present invention, in which a plurality of magnets 10 are arranged on the support side, and the magnet 10 at the center is arranged toward the levitation body 4.
The ferromagnetic material 3 in the position facing the magnetic pole of the
The diamagnetic body 5 is arranged at the magnetic pole facing position, and the attraction force and the repulsion force can be appropriately adjusted as a whole, and in particular, the lateral displacement of the levitation body is corrected. It becomes possible.

Next, the principle by which the levitation operation of the levitation body can be carried out by the magnetic levitation device configured as described above will be explained together with its action.

In the case of a ferromagnetic material, it is known that there is a characteristic as shown in FIG. 3 between the magnetic field strength H and the magnetization M, and the magnetic field strength H has a predetermined value H _c . beyond, so the value of the magnetization M is saturated at a certain saturation value M _s at higher.

Further, the energy U _m of the magnetic field is represented by U _m = −HM ···, so the force F acting on the object is F = −grad U _m = grad (HM ···).

Note that in forming a magnetic field, a strong magnet such as a rare earth cobalt magnet can be used in recent years, and an ordinary electromagnet or a superconducting magnet may be used. You can

Thus the time of the magnetization M is M = M _s (constant) and since the suction force F ₊ is F from the equation _{+ = (M s grad) H} ... Meanwhile, repulsive force by the diamagnetic F _- is, F _- = grad (H · x _A H) = x _A grad (H ² ) = 2x _A (H grad) H Here, x _A = −10 ⁻⁴ <0, and the formula and the force acting per unit volume. Indicates.

Therefore, it is possible to create a stable point by adjusting the volume ratio of the ferromagnetic material and the diamagnetic material and the magnetic field gradient, which will be described below with reference to FIGS. 4A and 4B.

In FIG. 4A, it is assumed that the vertical direction is the Z axis and the magnetic field strength H _z in the Z axis direction is linearly strong as H _z = H ₀ × Z. Incidentally, the pick only a component in the Z-axis direction of the force F and the magnetization M and the magnetic field strength _{H, F + = F s H} 0 ... F - = 2x A H 0 2 Z ... Note here formula suction force F It is shown that ₊ becomes constant regardless of the distance in the saturated region, and the formula shows that the repulsive force F ₋ increases as the magnetic pole approaches. Before the saturation region, the attractive force F ₊ increases rapidly as it approaches the magnetic pole, as shown in FIG. 4B.

Accordingly, ferromagnetic and the volume of the diamagnetic V ₊ and V respectively _- When the force F to be used in levitation _{body, F = V + × F +} + V - × F - ... Thus the weight of the levitated object W Then, as shown in Fig. 4B, there is a stable point at point A on the graph,
The force F decreases when it gets closer to the magnetic pole, and the force F when it gets farther.
Since the number of floating bodies increases, the floating body is held at this stable point A.

〔The invention's effect〕

As described in detail above, according to the present invention, magnetic levitation can be realized without contact without using an external control circuit.

In the above description, the ferromagnetic material and the diamagnetic material are provided on the levitation body side, but on the contrary, a magnet is provided on the levitation body side to reverse the relationship between the levitation body and the support body. It is also possible to levitate the side of the levitating body provided with the magnet.
In this case, by using a rail-shaped support made of a ferromagnetic material and a diamagnetic material, a magnetic levitation transfer device without a lead wire can be similarly constructed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of a magnetic levitation device of the present invention, FIG. 2 is a schematic diagram of another embodiment of the present invention, and FIG. 3 is an HM characteristic curve showing magnetic characteristics of a ferromagnetic material. FIG. 4A is an explanatory diagram showing the relationship between the attraction force F ₊ and the repulsive force F ₋ acting on the ferromagnetic substance and the diamagnetic substance and the distance thereof in relation to the magnetic field strength H, and FIG. 4A is an explanatory diagram showing that stable points are obtained in a saturation region of a ferromagnetic body by forces F ₊ and F ₋ acting in the Z-axis direction shown in FIG. 4A. 1,10 ... Magnet, 2 ... Magnetic pole, 3 ... Ferromagnetic material, 4 ... Levitator, 5 ... Diamagnetic material.

Claims (1)

[Claims] 1. A levitation body and a means for levitating the levitation body are provided with a ferromagnetic body and a diamagnetic body, and the other body is magnetically saturated in a saturation region of a high magnetic field. A magnet having a magnetic pole is provided, and in the saturation region, the ferromagnetic body is attracted by the magnet in a magnetically saturated state, and the attraction force and the repulsive force that repels the weight of the levitation body and the diamagnetic body. The magnetic levitation device is characterized in that the levitation body is kept in a levitated state at a stable point where the two are balanced.