JPH01247822A - Support construction for rotary shaft - Google Patents

Abstract

PURPOSE:To enhance supporting rigidity with simple construction by using a superconducting material for constituting one of the rotary shaft support part of a bearing and the part of the rotary shaft supported with the bearing, and using a multipolar-magnetized material for constituting the other. CONSTITUTION:A taper face 7 constituted with a superconducting material is formed on both ends of a rotary shaft 4 and made opposite to the taper face 8 of a bearing part 6 in a male-female relationship. Also, the bearing part 6 is a permanent magnet and the taper face 8 is magnetized alternately at the predetermined intervals with reverse magnetism radially from the center of rotation. Consequently, high supporting rigidity becomes available with simple construction.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a support structure for a rotating shaft.

(Prior art) Conventionally, magnetic bearings or gas bearings have been used instead of ball bearings for the bearings of rotating spindles for disks and polygon mirrors that rotate at high speed and require a particularly clean environment and high precision, such as magnetic disk drives and laser scanners. Bearings that can support rotation without contact, such as bearings, are used.

(Problem to be solved by the invention) In such magnetic bearings and gas bearings, the position of the rotating shaft is detected and the position relative to the rotating shaft is maintained constant using magnetic attraction or air springs. I was in control. However, in order to perform this control, not only a complicated control mechanism and a pressure adjustment mechanism are required, but also a large amount of electric power and a large structure are required for rotational support.

On the other hand, unlike the above-mentioned suction application, magnetic bearings have
Some use the repulsive force between magnets.

In principle, this method can obtain repulsive force with a simple structure, but it has a drawback that the support rigidity is low and a completely non-contact state cannot be obtained.

The present invention has been made based on the above circumstances, and its object is to provide a support structure for a rotating shaft that is simple in structure and has high support rigidity.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a structure in which a rotating shaft is supported by a bearing, wherein at least the supporting portion of the rotating shaft in the bearing or the rotating shaft is supported by a bearing. One of the supported parts of the shaft by the bearing is made of superconducting material,
The gist of the present invention is that the other is constituted by a multi-pole magnet.

<Function> In the support structure for the rotating shaft according to the present invention, focusing on the diamagnetic property exhibited when the superconductor is disposed facing the magnet, among the supporting part of the bearing and the supported part of the rotating shaft, One of them is made of a superconducting material, and the other is made of a multi-pole magnet.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view of an embodiment in which a rotating shaft support structure according to the present invention is applied to a rotating spindle of a magnetic disk device. In the figure, 1 and 2 are a housing and a cover, respectively, which constitute a magnetic disk device. 3 is a magnetic disk which is a magnetic medium. 4 is a rod-shaped rotating shaft. Taber surfaces 7 made of superconducting material are formed at both ends thereof. Here, as the superconducting material, for example, N
These include alloy materials such as b-Ti and Y-Ba-Cu-0 oxide materials. The tapered surface 7 is disposed opposite to the tapered surface 8 of the bearing portion 6 in a male-female relationship. One end of the rotating shaft 4 further extends to pass through a hole 9 formed in the center of the bearing 6, and is connected to the rotor 5 of the spindle motor. A plurality of magnetic disks 3 are fixed in a V4 layer on the outer periphery of the rotating shaft 4, and the rotating shaft 4 is driven by a spindle motor.
It is made to rotate at high speed along with the rotation of. The bearing portion 6 is made of a permanent magnet and is fixedly arranged on the housing 1 and the cover 2. As shown in Fig. 2, the tapered surfaces 8 of the bearing part 6 are magnetized radially from the center of rotation of the bearing part 6, with opposite polarity and alternately at a constant interval (pitch). (illustrated by white area).

As shown in Fig. 3, the magnetization may be done radially from the rotation center of the bearing section in two stages, upper and lower, at different pitches and with opposite polarity, and magnetization may also be done radially from the rotation center of the bearing section. It does not have to be in a spiral shape, for example, it may be in a spiral shape.

The operation of this embodiment in the above configuration will be explained.

As is well known, superconducting materials exhibit complete diamagnetism, the so-called Meissner effect, in which the magnetic flux of an external magnetic field does not penetrate into the material at all below a critical temperature. By utilizing this characteristic, non-contact, uncontrolled magnetic levitation in all directions, which is considered impossible with ordinary magnetic bearings, is possible. However, in reality, the combination of a magnet with a simple structure and a superconducting material has drawbacks such as low support rigidity, so it is necessary to take some measures to the structure of the magnet to control the shape of the generated magnetic flux.

Incidentally, the supporting rigidity required for a magnetic bearing increases as the magnetic flux density at which the magnetic flux generated by the magnet is rejected by the superconducting material increases. That is, the smaller the gap d between the magnet and the superconducting material, the higher the supporting rigidity.

For example, when the permanent magnets of the bearing portion 6 are repeatedly magnetized with opposite polarities at a constant pitch as shown in FIG. 2, the magnetic flux density φ is expressed as follows.

φ=φoeXl)(-πd/L) Here, φ0 is the magnetic flux density on the surface of the permanent magnet. From this equation, it can be seen that as the pitch L becomes smaller, the magnetic flux density generated from the permanent magnet decreases rapidly as it moves away from the magnet surface, that is, the magnetic flux concentrates near the magnet surface, and as the gap d becomes smaller, that is, It can be seen that the closer you get, the more rapidly the magnetic flux density increases exponentially. therefore,
Very high support rigidity can be obtained by reducing the pitch L and bringing the gap d closer to the magnet. However, although supporting rigidity increases by reducing the pitch L, in reality, a superconducting material that should exhibit perfect diamagnetism may have layers that do not exhibit perfect diamagnetism due to changes in the component composition in the surface layer, for example. When the pitch is set to 1 μm or less, magnetic flux is allowed to enter, resulting in a decrease in support rigidity. For this reason, if the shortest pitch is several μm or more, high support rigidity can be obtained with a gap d equivalent to the pitch. By repeating such a pitch, the magnets are magnetized to opposite polarities and provided on the housing 1 and the cover 2. The spindle of the magnetic disk device shown in FIG. 1 has a rotating shaft 4 having a tapered bearing portion 6 and a tapered surface 7 made of a superconducting material on the upper and lower sides facing the bearing portion 6. The rotating shaft 4 is supported on the center line and rotates at high speed with good stability.Also, the distribution of rigidity in each direction is determined depending on the purpose of use. It can be freely changed by setting the Taber angle.

In addition, since the gap between the bearing part and the shaft is much smaller than that of conventional magnetic bearings, stable operation is possible without the braking effect caused by environmental gas entering and exiting due to gap fluctuations during rotational operation.

In order to manufacture the permanent magnet facing surface of the bearing part 6 of the rotating shaft 4 from a superconducting material, for example, if it is made of an alloy material such as Nb-Ti, a sleeve of superconducting material processed into a tapered shape is attached to the shaft. Join or YBa 2 CLJ30
This is done by coating the shaft material with the raw material of the 7-series oxide material, heat-treating it, and then grinding it. Furthermore, the entire shaft may be made of superconducting material.

Therefore, according to this embodiment, focusing on the Meissner effect of superconductors, the superconducting magnetic bearing is simple because it uses a rotating shaft made of a bearing part and a superconducting material that are magnetized with opposite polarity repeatedly at a constant pitch. This structure provides high support rigidity.

In this embodiment, a tapered bearing part and a rotating shaft facing the tapered bearing part are used, but the present invention is not limited to this. For example, as shown in FIG. 4, a multi-pole magnetized ring and this It may be a combination of a bearing part with a magnetized bottom joined like a ring, and a shaft (not shown) having an opposing surface made of a superconducting material that faces the bearing part and the magnetized surface. .

Further, in this embodiment, the present invention is applied to a rotating spindle of a magnetic disk device, but the present invention is not limited to this, and may be applied to a rotating spindle of a polygon mirror of a laser scanner, for example. .

Furthermore, although a permanent magnet was used as the magnet in this example,
The present invention is not limited to this; for example, an electromagnet may be used.

Another advantage is that as the superconducting material rotates, any part of the superconducting material repels the alternating magnetic field, thereby improving rigidity due to the so-called induced repulsion effect.

[Effects of the Invention] As explained above, according to the present invention, attention is paid to the diamagnetic property exhibited when a superconductor is disposed facing a magnet, and any of the supporting portion of the bearing and the supported portion of the rotating shaft is One of them is made of a superconducting material, and the other is made of a multi-pole magnet, so it is possible to obtain a high support rigidity with a precise structure.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of one embodiment of the present invention, and FIGS. 2 to 4 are perspective views of the embodiment of the bearing portion and shaft. 1... Housing 2... Cover 3... Magnetic disk 4... Rotating shaft 5...
Rotor 6...Bearing part 7.8...Tapered surface 9...Through hole Agent Yasuo Miyoshi, patent attorney Figure 3, Factor 4

Claims (1)

[Claims] (1) A structure in which a rotating shaft is supported by a bearing, in which at least one of the supporting portion of the rotating shaft in the bearing or the supported portion of the rotating shaft by the bearing is made of a superconducting material, and the other is made of a superconducting material. A support structure for a rotating shaft characterized by comprising a multi-pole magnetized magnet.