JPH01182620A - Magnetic bearing - Google Patents

Abstract

PURPOSE:To let a device be composed of a small number of electromagnets, and thereby contrive to make the device small in size with its axial depth contracted by arranging three electromagnets radially arranged in each of two stages in the axial direction, letting the section to be attracted of a rotor corresponding to said electromagnets be of a conical surface, and thereby letting them be faced with each other while a gap spaced to magnetic poles is being maintained. CONSTITUTION:Electromagnets composed of three each 2a through 2c and 2d through 2f are arranged in each of two stages perpendicular to the shaft of a rotor 1 respectively, and a conical surfaces 5 and 6 corresponding to these magnets are formed onto the rotor 1. In addition, these three magnets 2a through 2c are arranged in such a way that respective magnetic force is directed in the radial direction so that attractive force is exerted mutually against the rotor 1 in order to support the rotor while a gap is being maintained. Hence, the electromagnets in these two stages can be closely piled up, a device can thereby be composed of a small number of electromagnets so as to be made small in size with its axial depth contracted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a magnetic bearing that supports a rotating body in a non-contact manner by magnetic force.

[Prior Art] Magnetic bearings that support a rotating body in a non-contact manner using the attractive force of a magnet have been known.

FIG. 7 shows a conventional magnetic bearing. 101 is a rotating body, 10
2 is an electromagnet, and 4 electromagnets are arranged on each of the two surfaces perpendicular to the axis with a gap maintained on the cylindrical surface of the rotating body.
There are 2 pieces on both end faces of 01, 10 pieces in total. 10
3 is a displacement sensor with a rotating body 101 on two surfaces perpendicular to the axis.
Two pieces are provided each facing the cylindrical surface of the rotating body +01, and one piece is provided on one end face of the rotating body +01. The number of these displacement sensors 103 is 5
5 corresponds to 5 degrees of freedom as a rigid body to be controlled, excluding the rotation of the rotating body 101 around the axis. A set of two electromagnets 102 generates a force in one direction, and a total of five sets support the rotating body 101 in a non-contact manner. The reason why electromagnets are arranged in groups of two or more is that since electromagnets cannot generate repulsive force, they can be supported without contact by balancing their attractive forces. Electromagnet 102
is driven by a control circuit (not shown) that generates a control current based on the clearance detection signal of the displacement sensor 103,
Balance the above suction power.

[Problems to be Solved by the Invention] However, in the structure of the magnetic bearing in the above-mentioned conventional technology, although there is little interference between the force of one set of magnets and the force of another set of magnets, the number of magnets and therefore the number of parts is large. However, there was a drawback that the length increased in the axial direction.

This structure is especially inconvenient when applied to precision rotating bodies that will serve as recording media for small storage devices that will be realized in the future in the technical field of electronic computer systems.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a magnetic bearing that has a small number of magnets and can be manufactured in a small size.

[Means for Solving the Problems] The configuration of the magnetic bearing of the present invention for achieving the above object includes: a rotating body, a plurality of displacement sensors that detect the clearance between the rotating body, and a signal from the displacement sensor. In a magnetic bearing equipped with a plurality of electromagnets whose magnetic force can be controlled by: three electromagnets on each of two planes perpendicular to the axis so that the magnetic force is oriented radially in three directions, for a total of six electromagnets. and two parts of the rotating body form conical surfaces, and the magnetic poles of the electromagnets are opposed to the conical surfaces so as to maintain a gap.

[Function] In the present invention, the number of magnets on each of the two surfaces perpendicular to the axis is three, and the magnetic poles and the surface of the rotating body facing the magnetic poles are arranged so that the magnets on the two surfaces also exert force in the axial direction. A total of 6 magnets are used as part of the cone to remove the rotation of the axis of the rotating body (the remaining 5
It is characterized by restricting degrees of freedom without contact. Therefore, it is possible to provide a magnetic bearing that has fewer parts and is short in the axial direction and is suitable for miniaturization.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIGS. 1 and 2 are a perspective view and a plan view showing an embodiment of the present invention. 1 is a rotating body; 2a, 2b, and 2C are a set of electromagnets provided on one plane perpendicular to the rotation axis of the rotating body 1; 2
d, 2e, and 2f are sets of electromagnets 3a, 3b, 3c, and 3d, which are also provided on other planes perpendicular to the rotation axis of the rotating body 1.
, 3e is a displacement sensor for controlling the magnetic force of the electromagnet by detecting the non-contact state of the remaining 5 degrees of freedom excluding the rotation of the axis of the rotating body l, 4a, 4b, 4c, 4d, 4e, 4
f is a coil wound around each of the electromagnets 2a to 2f, and 5.6 is a conical surface formed on a part of the rotating body 1 to be attracted. The rotating body 1 may be directly connected to a motor and rotated, as will be described later, or may be rotated via a rotation transmission mechanism. Three electromagnets 21 to 2f are provided on two surfaces perpendicular to the axis of the rotating body l, and are opposed to the rotating body l at a conical surface portion 5.6, and the magnetic poles of the electromagnet 2 facing the rotating body l are A part of the conical surface is also formed in the conical surface portion 5.6. In Fig. 2, three electromagnets 2a, 2b, and 2c on a plane perpendicular to the rotation axis are arranged so that the direction of their magnetic force is radial, and they mutually exert an attractive force on the rotating body l. Support this while maintaining the clearance. These three magnets are sufficient to balance the forces in this plane. In Figure 2, the directions of the forces of the electromagnets are 1
Although it is drawn to form an angle of 20 degrees, the arrangement does not have to be limited to this angle. Furthermore, in the present invention, as shown in Fig. 2, there are two sets of these three electromagnets, and their attractive force acts on the conical surface portion 5.6 of the rotating body, and also exerts a supporting force in the axial direction of the rotating body l. .

As a result, the remaining five degrees of freedom excluding the axial rotation of the rotating body I can be restrained in a non-contact manner by the control force of a total of six electromagnets 2.

3 is a side view of a modification of the rotating body of the embodiment shown in FIG. 1, and FIG. 4 is a side view of only the rotating body. 1st
In the figure, for ease of understanding, electromagnets 2a to 2 on each side are shown.
Although the parts f are shown separated in the axial direction, the effect of the present invention becomes even more remarkable when assembled closely stacked as shown in Fig. 3. That is, as shown in FIG. 2, the electromagnets 2a to 2f on different surfaces are arranged radially at different angles, so even if the coils 4a to 4f protrude from the yoke surface of the electromagnets 2a to 4f, , a set of three electromagnets 2a, 2b, 2c (partially not shown) of each of these two different types, and 2
There is no way to prevent the pairs d, 2e, and 2f (partially not shown) from being closely overlapped. As a result, the magnetic bearing of the present invention can be made smaller in length in the axial direction. At this time, the displacement sensor 3e that detects the axial displacement of the rotating body 1 can be configured to have a small axial length, and this does not prevent the length of the magnetic bearing from being shortened.

FIG. 5 shows another embodiment of the present invention, in which the shape of the rotating body is different from that shown in FIG. 4, and the conical surface of the rotating body is configured to be thin. Therefore, a cylindrical fixing part (not shown) is used to house the rotating body l and fix the electromagnets 2a to 2f (- part not shown) and the displacement sensors 3a to 3e.
Since it is possible to insert the rotating body 1 into the hole later, the fixed part becomes one member that is not divided into upper and lower parts, and accurate cylindrical processing is possible, and each part can be installed and stored in a perfect circle. You will be able to do it in a controlled manner.

FIG. 6 is a block diagram for explaining a control system that maintains a gap between the electromagnet and the rotating body, in which 8 is a differential circuit, 9 is a displacement signal calculation section, 10 is a signal processing and power amplifier, and 11 is a gap. Although FIG. 7 is representatively drawn for one electromagnet 2, in reality, for example, five differentiating circuits 8 and displacement signal calculation units 9 are provided corresponding to the sensors 3, and the signal processing and power amplifier lO is provided for the electromagnet. 6 are provided corresponding to 2. A signal voltage generated by the displacement sensor 3 according to the clearance between the displacement sensor 3 and the rotating body 1 is input directly to the displacement signal calculation unit 9 and also input as a speed signal through the differentiating circuit 8 . Using this speed signal, damping can be applied and the control system that maintains the clearance can be stabilized. The displacement signal calculation section 9 multiplies the signal voltage and speed signal by appropriate constants depending on the displacement state, and distributes them to each signal processing and power amplifier IO. The distributed signals are appropriately added and amplified by the signal processing and power amplifier 10 and fed back to control the current in the coil 4 of the electromagnet 2 and maintain the gap 11.

The magnetic bearing of each of the embodiments described above has two
A set of electromagnets installed in each stage radially attracts the rotating body in three directions and supports the circumferential direction of the shaft without contact.
Further, on the conical surface of the attracted portion of the rotating body, each set of the electromagnets mutually attracts the rotating body in the axial direction, thereby supporting the rotating body in a non-contact manner in the axial direction as well. As a result, the number of electromagnets in each set is reduced by one, and two axial electromagnets can be omitted, making it possible to support the rotating body with a total of six electromagnets. Furthermore, by omitting the electromagnet in the axial direction and increasing the spacing between the electromagnets in each stage, making it possible to closely stack the two stages of electromagnets, it is possible to provide a compact bearing that is short in the axial direction.

As described above, the present invention can be applied in various ways in accordance with its gist and can take various embodiments.

[Effects of the Invention] As is clear from the above description, according to the magnetic bearing of the present invention, the three electromagnets each arranged radially and exerting an attractive force on each other are arranged in two stages in the axial direction, and the rotating body is covered with The suction part is a conical surface so that these electromagnets attract the rotating body to each other in the axial direction, and these two stages of electromagnets can be arranged so that they can be closely stacked, so the number of electromagnets is as small as 6. This has the advantage of being able to provide a compact bearing that is short in the axial direction.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a side view of a modification of the above embodiment, FIG. 4 is a side view of only the rotating body, and FIG. FIG. 5 is a side view showing another embodiment of the present invention, FIG. 6 is a block diagram of a control system, and FIG. 7 is a perspective view of a conventional magnetic bearing. 1-...Rotating body, 2.2a, 2b, 2c, 2d, 2e
,, 2 f-electromagnets, 3, 3a, 3b, 3c, 3d. 3 e-displacement sensor, 4.4a, 4b, 4c, 4d,
4e, 4f...Coil, 5.6...Conical surface, lO・
··Gap. 1-------One rotating body 2a, 2b, 2c, 2d, 2e, 2f----Snow 5t
'ffJ3a, 3b, 3c, 3d, 3e------
9i 2inbo 4o, 4b, 4c, 4d, 4e, 4f--
---) A ν5, 6 --- One conical surface Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7

Claims (1)

[Claims] (1) In a magnetic bearing comprising a rotating body, a plurality of displacement sensors that detect the clearance between the rotating body and a plurality of electromagnets whose magnetic force can be controlled by signals from the displacement sensors, two orthogonal to the axis are provided. Three of the electromagnets are arranged on each plane so that their magnetic forces are directed in three directions, for a total of six, and two parts of the rotating body form conical surfaces, A magnetic bearing characterized in that the magnetic poles of an electromagnet are opposed to the conical surface so as to maintain a gap.