JPH0456896B2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to magnetic radial bearings.

(Prior Art) As a conventional magnetic radial bearing, one shown in FIG. 1 is known. That is, a housing 2 is provided around the rotating shaft 1, and a magnetic repulsion structure consisting of permanent magnets 3 and 4 is accommodated within the housing 2. Here, the permanent magnets 3 and 4 are ring-shaped and magnetized in the radial direction, with one permanent magnet 3 being fixed to the rotating shaft 1 and the other permanent magnet 4 being fixed to the housing 2. Since the permanent magnets 3 and 4 are polarized so that they magnetically repel each other in the radial direction, the rotating shaft 1 is connected to the permanent magnets 3 and 4.
It is floatingly supported by the housing 2 via. Therefore, even if the rotating shaft 1 rotates, no loss due to friction should occur.

However, since this bearing is not positioned in the thrust direction, the rotating shaft 1 and the housing 2 change their relative positions in the thrust direction, and the permanent magnet 3 is placed inside the end surface of the housing 2 as shown in the figure.
The end of the thrust direction may collide.

(Object of the invention) The present invention has been made in consideration of the above points, and
It is an object of the present invention to provide a magnetic radial bearing that is difficult to displace in the thrust direction and can prevent contact between a movable part and a fixed part due to displacement in the thrust direction.

(Summary of the Invention) In order to achieve this object, in the present invention, disk-shaped magnets with a large diameter and disk-shaped magnets with a small diameter are arranged alternately in the axial direction on the rotating shaft. The present invention provides a magnetic radial bearing in which ring-shaped magnets with a large inner diameter and ring-shaped magnets with a small inner diameter are arranged alternately in the axial direction so as to mesh with the disk-shaped magnets.

(Example) The present invention will be described below with reference to FIG. 2 by way of example.

In FIG. 2, the rotating shaft 1 is provided with a small-diameter disk-shaped permanent magnet 3a and a pair of large-diameter disk-shaped permanent magnets 3b sandwiching the small-diameter permanent magnet 3a in the axial direction. A ring-shaped magnet 4a with a small inner diameter and a ring-shaped magnet 4b with a large inner diameter are provided radially opposite to the permanent magnets 3a and 3b on the rotating shaft side. These ring-shaped magnets 4a, 4b are fixed to the peripheral wall 2a of the housing,
An end plate 2b of the housing is provided on the end face of the outermost magnet 4b in the axial direction. An end plate 3c is also provided at the outermost end in the axial direction of the disc-shaped magnet 3b so as to be aligned with the end plate 2b.

In this configuration, the magnets 3a and 3b on the rotating shaft side
and magnets 4a and 4b on the housing side (fixed side) are arranged so as to mesh with each other in the axial direction. In other words,
The small diameter magnet 3a on the rotating shaft side faces the small inner diameter magnet 4a on the housing side, and the large diameter magnet 3b on the rotating shaft side faces the large inner diameter magnet 4b on the housing side.

And these magnets 3a, 3b and 4a, 4
Both of the magnets b are magnetized in the radial direction, and the opposing portions of the magnets have the same magnetic pole. For example, the inner circumferential edge of the magnet 4a on the housing side is a north pole, but the portions of the surrounding magnets 3a and 3b that face the inner circumferential edge of the magnet 4a are all north poles. Magnetic repulsion is produced between the inner circumferential edge of the magnet 4a and the outer circumferential edge of the magnet 3a, and between the inner circumferential portion of the magnet 4a and the outer circumferential portion of the magnet 3b. In order to make this repulsive effect strong, the gap length between the magnets to be magnetically repelled should be made as small as possible, but if it is too small, the magnets will easily come into contact with each other, so it is necessary to select an appropriate size.

With this configuration, when the rotating shaft 1 rotates, the disk-shaped magnets 3a and 3b also rotate. At this time, the outer peripheral edges and outer peripheral portions of the magnets 3a and 3b magnetically repel the inner peripheral edges and inner peripheral portions of the magnets 4a and 4b on the housing side, so that the rotating shaft 1 also thrusts in the radial direction with respect to the housing 2. Even if it is slightly displaced in the direction, it will not be displaced beyond a certain level and will remain approximately at a predetermined position. As a result, the rotation axis 1
is supported by the housing 2 in a completely non-contact manner.

(Modification) In the above embodiment, the magnet array on the rotating shaft side is such that the small diameter magnet is in the middle and the large diameter magnet is on both sides in the axial direction. You can also do this. Further, the number of opposing pairs of magnets on the rotating shaft side and the housing side is not limited to the three pairs in the above embodiment.

(Effects of the Invention) As described above, the present invention includes a plurality of disk-shaped permanent magnets with different diameters on the rotating shaft, and a plurality of ring-shaped permanent magnets with different inner diameters on the housing, which are arranged opposite to the disk-shaped permanent magnets. Since magnetic repulsion is caused between the rotating shaft and the housing by using the magnetic radial bearing, it is possible to provide a magnetic radial bearing that is difficult to displace not only in the radial direction but also in the thrust direction and supports the rotating shaft completely without contact. . Furthermore, displacement in the thrust direction is prevented by a permanent magnet for magnetic repulsion in the radial direction, and another feature is that the magnets are effectively utilized.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of a conventional magnetic radial bearing.
FIG. 2 is a longitudinal sectional view of an embodiment of the present invention. 1... Rotating shaft, 2... Housing, 3... Rotating shaft side magnet, 4... Housing side magnet.

Claims (1)

[Claims] 1 A rotating shaft in which small-diameter disk-shaped permanent magnets and large-diameter disk-shaped permanent magnets are arranged alternately in the axial direction, and corresponding to the disk-shaped magnets on this rotating shaft, ring-shaped magnets with small inner diameter and large inner diameter ring-shaped magnets are arranged alternately in the axial direction. It has a housing in which ring-shaped magnets are arranged alternately in the axial direction,
A magnetic radial bearing that supports the rotating shaft in a non-contact manner by causing magnetic repulsion between a disk-shaped magnet of the rotating shaft and a ring-shaped magnet of the housing.