JPS62270823A - Magnetic bearing - Google Patents

Abstract

PURPOSE:To eliminate a non-modulation gap and facilitate design and control with simple construction using less number of electromagnetic coils by furnishing a rotor and a stator each having two yokes forming two sets of gap magnetic paths facing each other. CONSTITUTION:Flux PHI1 is passed from N to S pole of a permanent magnet 9 of a rotor 1. That is, from a gap magnetic path G1 via solenoid yokes 6, 7 of the stator, the flux PHI1 shall flow into a gap magnetic path G1. Then the flux PHI1 shall flow into the yoke 5 from the yoke 7 through a gap magnetic path G2 for returning to the S pole, and thereby magnetic attraction force is applied to said gap magnetic paths G1, G2 between the yokes 4, 6 and 7, 5. Displacement of the rotor 1 is sensed by a location sensor 13 for X axis, and current is allowed to flow in solenoids 12a, 12c to allow a flux PHI2 to flow in such a direction as to set off change of the attraction force of the flux PHI1 caused by the permanent magnet 9. Thereby the whole attraction force is balance, and the rotor 1 is restored to the neutral position as original.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Field of Application] The present invention provides a mechanism for attracting a rotor to a stator by an interaction between the attractive force of a permanent magnet and the electromagnetic attractive force of an electromagnetic coil. This invention relates to a magnetic bearing with a simple structure that supports contactless support.

[Prior technology] Magnetic bearings support rotating objects! This is a bearing that uses magnetic force to generate force. These magnetic bearings have been developed in recent years due to their remarkable features such as no life limit due to friction or fatigue, extremely low frictional torque, and excellent suitability for special environments such as high temperatures and low temperatures. There is a lot of research going on. As for this application, for example, use in centrifugal separators, molecular pumps, gyroscopes, precision measuring instruments, control equipment for artificial satellites, etc. is considered to be promising.

However, most conventional magnetic bearings use eight electromagnetic coils each, and their structure is complex, as well as having a so-called non-modulation gap through which only the magnetic flux of the permanent magnet passes. This makes design and control difficult and increases the burden on the power supply.

[Object of the Invention] An object of the present invention is to provide a magnetic bearing that has a relatively simple configuration with a reduced number of electromagnetic coils, has no non-modulation gap, and is easy to design and control.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a rotor section comprising a rotor section and a stator section each having two yokes forming two sets of air gap magnetic paths facing each other, The stator part has a permanent magnet sandwiched between the yokes, and the stator part has three or more iron cores arranged between the yokes, and has an electromagnetic coil with a coil wound around each of these iron cores. It is a bearing.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

Fig. 1 is a cross-sectional view of the magnetic bearing, and Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, in which a rotor part 1 is provided at the center of rotation, and a stator part 2 is arranged around it. It is an inner rotor type.

The rotor portion 1 is attached to a shaft 3, and a similar rotor portion is provided at the other end of the shaft 3. The rotor portion 1 has an annular first rotor. It has second yokes 4.5, and these yokes 4.5 are provided with an air gap magnetic path G1. Annular first and second electromagnetic yokes 6.7 are provided on the stator portion 2, facing each other via G2. The first and second iW electromagnetic yokes 7 of the stator section 2 are radially divided into four parts, and a nonmagnetic material 8 is interposed between them. An annular permanent magnet 9 is arranged between the first and second yokes 4.5 of the rotor section 1. The first section of the stator section 2. Between the second electromagnetic yokes 6.7, four iron cores 10a, 10b, loc, and 10d are interposed corresponding to the divisions of the electromagnetic yokes 6.7. And each iron core 10a, 10b, foe
, lOd have coils lla, llb, lie, respectively.
1lcl is wound, and constitutes electromagnetic coils 12a, 12b, 12c, and 12d that can independently generate magnetic flux.

Furthermore, a position sensor 13 for detecting displacement of the rotor part 1 in the X-axis direction and a position sensor 14 for the Y-axis direction are provided on the side of the rotor part 1.

-°) From the sensor 14, the electromagnetic coils 12b,'
A current is applied to 12d. The permanent magnets 9 of the rotor part 1 are surrounded by a protective ring 15 made of a non-magnetic material, a connecting part 16 made of a non-magnetic material is attached to the stator part 2, and a similar stator part is attached to the other end. It is provided.

During operation, a magnetic flux φ passes from the N pole to the S pole of the permanent magnet 9 of the rotor section l, that is, the magnetic flux φ passes from the air gap magnetic path G1 through the electromagnetic yoke 6.7 of the stator section 2 to the air gap magnetic path Gl.
l flows into the magnetic flux φ1 from the electromagnetic yoke 7 to the air gap magnetic path C.
2 to the electromagnetic yoke 5 and return to the S pole.
A magnetic attraction force acts on the air gap magnetic paths G1 and G2 between the yokes 4 and 6 and 7ψ5. Considering an ideal situation, this magnetic attraction force is canceled out in all directions,
The rotor portion l is not displaced in the radial direction,
Although it may be in an unstable equilibrium state, in reality, it is inevitable that the rotor section 1 will be displaced in the □ flat radial direction due to manufacturing precision and the influence of gravity. , the rotor section 1 moves a minute amount in the positive direction of the X-axis. G2 is narrow, and the air gap magnetic paths C1 and G2 on the left side are large. Therefore, the right air gap magnetic path G1. Since the magnetic resistance of G2 is small, the permanent magnet 9 in this part
The magnetic flux φ1 from the magnetic flux φ1 further increases, the attractive force increases during this time, and the magnetic flux φ1 passing through the left air gap magnetic paths G1 and G2 decreases, so that the rotor portion 1 is increasingly drawn to the right side.

This displacement is detected by the position sensor 13 around the X-axis,
A current is applied to the electromagnetic coils 12 & 12c based on the control signal from the control circuit, and the direction is such that the change in the attraction force of the magnetic flux φ due to the permanent magnet 9 is canceled out, that is, the air gap magnetic path G on the right side.
1 and G2, the magnetic flux φ2 passes in the opposite direction to the magnetic flux φ1 of the permanent magnet 9, and in the left air gap magnetic paths G1 and G2, the magnetic flux φ2 flows in the same direction as the magnetic flux φ1. This magnetic flux φ2 offsets the change in the magnetic flux φ1 from the permanent magnet 9 due to displacement, and reduces the attractive force in the right air gap magnetic paths Gl and G2.

] Air gap magnetic path G1 on the 14th side. In G2, the attraction force is increased in exactly the same way in the Y-axis direction.

In this case, the first and second electromagnetic yokes 6 of the stator section 2
．． By dividing 7 into the electromagnetic coils 12a to 12d as in the embodiment, the magnetic flux φ2 from the electromagnetic coils 12a and 12c passes only through the divided portions existing on the X-axis and the Y-axis. Since less of the magnetic flux flows into other divided parts, it is possible to efficiently use the magnetic flux for attraction. It should be noted that a considerable effect can be similarly obtained by providing a notch in a part of the electromagnetic yoke 6.7 instead of providing a divided portion as in the embodiment. Since this magnetic bearing has a small number of yokes, its rigidity in the thrust direction is slightly inferior, so although there is no problem when using it in zero gravity, in a place where gravity exists, the axial direction is horizontal and the thrust direction is affected by gravity. It is preferable to arrange the bearing so that there is no magnetic bearing, or to use a magnetic bearing in the thrust direction.

'i-', which is an inner rotor type arranged around the part 1, can also be made into an outer rotor type where the rotor part 1 is arranged around the stator part 2. Further, in the embodiment, an example is shown in which the yoke of the stator section 2 is divided into four parts, but control is possible if the yoke is divided into at least three parts.

[Effects of the Invention] As explained above, the magnetic bearing according to the present invention simplifies the configuration of the device by reducing the number of electromagnetic coils, and
Moreover, by eliminating the non-modulation gap, it has the advantage of reducing the burden on the power supply of the power used.

[Brief explanation of drawings]

The drawings show an embodiment of the magnetic bearing according to the present invention, and FIG. 1 is a cross-sectional view thereof, and FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1 is a rotor part, 2 is a stator part, 3 is a shaft, 4.5 is a yoke, 6.7 is an electromagnetic yoke, 9 is a permanent magnet, 10 is an iron core, 11 is a coil, 12 is an electromagnetic coil, 13 and 14 are position sensors. Patent applicant Director of Aerospace Technology Research Institute Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. Consists of a rotor section and a stator section each having two yokes forming two sets of air gap magnetic paths facing each other, and the rotor section has a permanent magnet sandwiched between the yokes. The magnetic bearing is characterized in that the stator section has three or more iron cores arranged between the yokes and electromagnetic coils each having a coil wound around each of the iron cores. 2. The magnetic bearing according to claim 1, wherein the yoke of the stator portion is divided into three or more parts corresponding to the coils. 3. The magnetic bearing according to claim 1, wherein the yoke of the stator portion has a large magnetic resistance at a boundary portion corresponding to the coil.