JPS5939611B2 - magnetic bearing - Google Patents

Description

[Detailed description of the invention] The present invention relates to magnetic bearings.

Conventionally, as shown in FIG.
It consists of a cylindrical bearing permanent magnet 3 arranged opposite to the outer periphery of the magnet, and the opposing surfaces of both magnets 2 and 3 are made to have the same polarity, or as shown in Fig. 1b. The axial sides of both cylindrical magnets 2 and 3 have the same magnetic pole, as shown in FIG.
Each magnet is magnetized so that the magnetic flux density distribution on the magnetic pole surface is substantially uniform.

However, in such a device, the equilibrium point of the axial force is unstable, and it is necessary to use a separate axial bearing to maintain the equilibrium point. In addition, in the case of a rectangular axial bearing, as shown in FIG. Both magnets 4 and 5 have the same polarity and are almost uniformly magnetized on their opposing surfaces. In such a bearing, the equilibrium point of the radial force is unstable, and the load on the radial bearing increases. In order to eliminate the above-mentioned drawbacks, the present invention is designed such that the rotating shaft side magnet and the stationary side magnet opposing the rotating shaft side magnet generate a repulsive force that returns each other to the original state when the rotating shaft side magnet is misaligned with the bearing side magnet. The present invention is characterized by its configuration, and will be described in detail below with reference to the drawings.

Fig. 3 shows an embodiment used in a repulsion type radial bearing, and shows the axial magnetic flux density distribution of the cylindrical permanent magnet 12 fixed to the rotating shaft 11 and the opposing poles of the cylindrical permanent magnet 13 on the bearing side. , the axial distance of the magnet is shown on the horizontal axis, and the magnitude of the magnetic flux density G is shown on the vertical axis. An M shape as shown in 1a in Figure 3b, and a symmetrical chevron shape as shown in 1b in Figure 3b. This is a combination of the two.

By making the permanent magnets 12 and 13 have such a combination of magnetic flux density distribution, the magnet 12 becomes the same as the magnet 13.
is stabilized at the center, and when an axial load is applied and the rotating shaft 11 and therefore the magnet 12 move in the axial direction, the M-shaped part with high magnetic flux density and the chevron-shaped part with high magnetic flux density will approach each other. Therefore, the repulsive force becomes stronger and the center of the magnet 12 is pushed back to the center of the magnet 13. In other words, restoring force in the axial direction can be obtained. FIG. 4 shows an embodiment used in a reversible axial bearing, in which the opposing magnetic poles of one of the disk-shaped permanent magnets 14 attached to the rotating shaft 11 and the disk-shaped bearing-side permanent magnet 15 are shown. Figure 4 shows the magnetic flux density distribution on the surface.
As shown in Figure 4, the magnetic flux density distribution is M-shaped with a valley at the center and a mountain at the periphery, and the magnetic flux density distribution of the other magnet is shaped like a mountain where the center is high and the outer circumference is low, as shown in Figure 4 (BO)H. It is.

When the rotating shaft 11 is shifted from the center, that is, when the center of the magnet 14 on the rotating side is shifted from the center of the magnet 15 on the bearing side, there is a repulsive force between both magnets 14 and 15 that returns the center of the magnet 14 to its original position. works and returns to normal. Therefore, almost no load is applied to the radial bearing (not shown) that supports the rotating shaft 11 in the radial direction. FIGS. 5 and 6 show another embodiment of the anti-saw type axial bearing, and the one shown in FIG. Electromagnet 2 facing 22
The magnetic pole face formed on the end face of the cylindrical iron core in No. 3 is shaved at the center to form a concave surface, and the magnetic flux density distribution on the virtual pole face before being shaved is M-shaped as shown in 1 in Figure b. None, the permanent magnet 22 fitted on the rotating shaft 11 is shown in the same figure BO
) It is shaped like a chevron like I.

The one shown in Figure 6 is one in which the magnetic pole face of the electromagnet 23' is shaved to have a medium height, and the magnetic flux density distribution on the virtual pole face before being shaved is made into a mountain shape as shown in Figure b (7) H. The magnetic flux density distribution on the magnetic pole surface of the permanent magnet 22' housed in the rotating shaft 11 is made into an M-shape as shown in (1) in FIG. What is shown in these figures 5 and 6 is the 4th
It has a similar effect to that of the embodiment shown in the figure. As described above, in the present invention, the rotating shaft side magnet and the stationary side magnet opposing the same generate a repulsive force that returns each other to their original state when the position of the rotating shaft side magnet facing the bearing side magnet shifts. Since radial bearings provide an axial bearing effect, and axial bearings provide a radial bearing effect, vertical shaft installation is stable, and radial bearings allow the axial bearing to be removed, simplifying the bearing structure. In addition, since the load on the radial bearing is reduced in the case of an axial bearing, a non-contact type radial bearing can be used.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional repulsion type radial magnetic bearing, Figure 2
The figure shows a front view of a conventional anti-spring type axial magnetic bearing, and Fig. 3 shows an embodiment of the present invention used in a radial bearing.
4 is a cross-sectional view, FIG. Fig. 5 is a diagram of the magnetic flux density distribution curve of a magnet, and shows an example used in a repulsion type axial bearing. Further different embodiments of the bearing are shown, in which Figure a is a cross-sectional view and Figure b is a magnetic flux density distribution curve diagram of a magnet. 11... Rotating axis, 12, 14, 22, 21...
... Rotating shaft side magnet, 13, 15 ... Bearing side magnet, 23, 23' ... Bearing side electromagnet.

Claims (1)

[Scope of Claims] 1. In a repulsion type magnetic bearing in which a rotating shaft side magnet and a bearing side magnet are arranged with the same poles facing each other, the magnetic flux density distribution on the opposing surfaces of the rotating shaft side magnet and the bearing side magnet is one side. has a chevron-shaped distribution where the center is strong and weak toward the ends, and the other has an M-shaped distribution where the ends are strong and the center is weak. A magnetic bearing characterized in that the central part of the M-shaped magnetic flux density distribution is arranged to face each other. 2. The rotating shaft side magnet is a cylindrical permanent magnet that is coaxial with the rotating shaft, and the bearing side magnet is a cylindrical permanent magnet that coaxially surrounds the rotating shaft side magnet, and both of the magnets have magnetic flux on their opposing surfaces. A patent characterized in that the density distribution is magnetized so that one side has a chevron-shaped distribution where the center is strong and the edges are weak, and the other side is an M-shaped distribution where the edges are strong and the center is weak. A magnetic bearing according to claim 1. 3 The rotating shaft side magnet is a disc-shaped permanent magnet provided perpendicular to the rotating shaft, the bearing-side magnet is a disc-shaped permanent magnet provided opposite to the rotating shaft side magnet, and both of the magnets are opposite to each other. The magnetic flux density distribution on the surface is magnetized so that one side has a chevron-shaped distribution where the center is strong and weak towards the edges, and the other side is an M-shaped distribution where the edges are strong and the center is weak. A magnetic bearing according to claim 1. 4. The rotating shaft side magnet is a disc-shaped permanent magnet provided perpendicular to the rotating shaft, the bearing side magnet is an electromagnet with a coil wound around an iron core provided opposite to the permanent magnet, and the permanent magnet is the electromagnet The magnetic flux density distribution on the facing surface is magnetized in such a way that it forms a chevron-shaped distribution where the magnetic flux density is strong in the center and weak towards the ends.
2. The magnetic bearing according to claim 1, wherein the electromagnet has a concave surface facing the permanent magnet of the iron core, and has an M-shaped magnetic flux density distribution that is strong at the ends and weak at the center. 5. The rotating shaft side magnet is a disc-shaped permanent magnet provided perpendicular to the rotating shaft, and the bearing side magnet is an electromagnet with a coil wound around an iron core provided opposite to the permanent magnet. The electromagnet is magnetized so that the magnetic flux density distribution on the surface facing the permanent magnet is an M-shaped distribution where the ends are strong and the center is weak. 2. The magnetic bearing according to claim 1, wherein the magnetic bearing has a mountain-shaped magnetic flux density distribution that is weaker toward .