JPH0126404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables non-contact support of the rotor section with respect to the stator section, as well as radial position control, through the interaction of the attraction force of the permanent magnets and the control attraction force of the electromagnetic coils. This invention relates to a radially controlled magnetic bearing.

A magnetic bearing is a bearing that uses magnetic force to support a rotating object. These magnetic bearings have become popular in recent years due to their remarkable characteristics, such as no life limit due to friction or fatigue, extremely low friction torque, and excellent compatibility with special environments such as vacuum, high temperature, and low temperature. Research is being conducted on As for this application, for example, use in centrifugal separators, vacuum molecular pumps, gyroscopes, precision measuring instruments, control equipment for artificial satellites, etc. is considered to be promising.

In general, permanent magnets are often used in low-consumption type magnetic bearings, and in many axial control types, the direction of magnetization is radial, but in reality, permanent magnets are magnetized in the radial direction. Manufacturing the magnet and magnetically connecting it to the yoke is difficult.

The present applicant previously filed a patent application filed in 1983 from this perspective.
A magnetic bearing magnetized in the axial direction was filed in No. 160376, but the thickness was large because both permanent magnets and electromagnets were stacked in two stages. However, if control around the radial axis is not required, it is possible to configure it with a simpler shape.

An object of the present invention is to provide a radially controlled magnetic bearing that uses a permanent magnet magnetized in the axial direction, has few parts, is thin, and has good performance. It consists of a rotor part and a stator part, each of which rotates around one center without contact with the other, and each of the rotor part and the stator part has two flat annular yokes arranged in parallel, and These two rotor part yokes and two stator part yokes face each other in the radial direction with an air gap magnetic path in between, and the yokes of the stator part or both of the rotor part and the stator part are arranged in an axial direction. sandwiching a magnetized permanent magnet, an electromagnetic coil is provided on an electromagnetic yoke that is magnetically joined to the stator section yoke, and one of the two air gap magnetic paths has magnetic flux only from the permanent magnet, On the other hand, the magnetic fluxes of both the permanent magnet and the electromagnetic coil coexist, so that the attractive force exerted by the permanent magnet between the yokes of the rotor part and the stator part is controlled by the attractive force by the electromagnetic coil. The invention is characterized in that the radial position of the rotor portion with respect to the stator portion is controlled by adjusting the stator portion.

The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a longitudinal sectional view of the first embodiment, and FIG. 2 is a plan view of the stator section 1 and rotor section 2. In this embodiment, a stator section 1 is integrally fixed to a shaft, and a rotor section 2 is configured to rotate around the stator section 1, and a flywheel is attached to the rotor section 2. The shaft and flywheel are not shown. Stator part 1
are two flat annular yokes with the same inner and outer diameters, that is, the first and second stator yokes 1.
1 and 12, and a permanent magnet 13 having an annular shape and magnetized in the axial direction is sandwiched between them.
As shown in FIG. 2, for example, the second stator yoke 12 has constrictions 14 having large magnetic resistance at four equiangular locations, and further has a cross-shaped electromagnetic yoke 15 attached thereto. This electromagnetic yoke 15 is magnetically connected to a separation section separated by a constriction section 14 of the second stator yoke 12. In addition, each leg portion 15a, 15b, 1 of the electromagnetic yoke 15
A total of four electromagnetic coils 16a, 16b, 16c, and 16d are wound around the coils 5c and 15d, one each.

On the other hand, in order to rotate around the first and second stator yokes 11 and 12 without contact, the rotor section 2 has two flat annular first and second rotor yoke 21,
22 are provided, and the pole magnets on the inner peripheral surfaces thereof are arranged so as to face the magnetic poles on the outer peripheral surfaces of the stator yokes 11 and 12, respectively. Further, a permanent magnet 23 magnetized in the axial direction is also sandwiched between the rotor yokes 21 and 22, similarly to the stator section 1. Note that the permanent magnet 23 of this rotor portion 2
The polarity of the permanent magnet 13 of the stator section 1 is opposite to that of the permanent magnet 13 of the stator section 1.

In FIGS. 1 and 2, 30 and 31 are position sensors for detecting the displacement of the rotor section 2 in the X-axis direction and the Y-axis direction, respectively, and the X-axis position sensor 3
The output of 0 passes through the compensation circuit 32 and the power amplifier 33, and is then sent to the legs 15a, 1 of the electromagnetic yoke 15 in the X-axis direction.
A current is caused to flow through electromagnetic coils 16a and 16c wound around the coil 5c. Similarly, the Y-axis position sensor 31 detects the legs 15b, 1 in the Y-axis direction.
A current is supplied to electromagnetic coils 16b and 16d wound around 5d.

Since this embodiment has the above-described configuration, the first stator yoke 11 and the first rotor yoke 21
There is only a magnetic flux φ ₁ due to only the permanent magnets 13 and 23, and the first stator yoke 11 and the first
The air gap magnetic path G1 between the rotor yokes 21 is a non-modulated gap. On the other hand, the second stator yoke 12 and the second rotor yoke 22 have
The magnetic flux φ ₁ from the permanent magnets 13, 23 and the magnetic flux φ ₂ generated from the electromagnetic coils 16a, . . . coexist, and the air gap magnetic path G2 between them is a so-called modulation gap.

During operation, magnetic flux φ ₁ passes from the N pole to the S pole of the permanent magnets 13 and 23, that is, the magnetic flux φ ₁ flows from the first rotor yoke 21 to the first stator yoke 11, and at the same time the second stator The magnetic flux φ ₁ flows from the yoke 12 to the second rotor yoke 22 . Therefore, due to the passage of this magnetic flux φ ₁ , a magnetic attraction force acts on the air gap magnetic paths G1 and G2 between the stator yokes 11 and 12 and the rotor yokes 21 and 22.

Considering an ideal situation, this attractive force is canceled out in all directions, and the rotor section 2 is in an unstable equilibrium state without being displaced in any particular radial direction. However, in reality, it is unavoidable that the rotor portion 2 deviates in one direction due to manufacturing precision and the like. For example, when the rotor section 2 moves a small amount in the positive direction of the X-axis, the stator section 1 in FIG.
The air gap magnetic paths G1, G2 on the left side between and the rotor portion 2 are narrow, and the air gap magnetic paths G1, G2 on the right side are large. Therefore, since the magnetic resistance of the left air gap magnetic paths G1 and G2 becomes small, the permanent magnets 13 and
The magnetic flux φ ₁ from the rotor 23 increases further, the attraction force increases during this time, and the magnetic flux φ ₁ of the right air gap magnetic paths G1 and G2 decreases, so that the rotor portion 2 is further drawn to the right side.

This deviation is detected by the X-axis position sensor 30, and the legs 15a, 1 of the electromagnetic yoke 15 in the X-axis direction are
A current based on the control signal of the compensation circuit 32 is caused to flow through the electromagnetic coils 16a and 16c provided in the electromagnetic coil 5c. As a result, the direction that cancels the change in the attractive force of the magnetic flux φ ₁ caused by the permanent magnets 13 and 23, that is, the air gap magnetic path G2 on the right side is directed to the second stator yoke 1.
The magnetic flux φ 2 passes from the rotor yoke 2 to the second rotor yoke 22, makes a half-circle around the rotor yoke 22, and returns from the rotor yoke 22 to the stator yoke 12 through the left air gap magnetic path _G2 . Due to this magnetic flux φ ₂ , the permanent magnets 13 and 2 are caused by the deflection of the rotor yokes 21 and 22.
By canceling the change in the magnetic flux φ ₁ from 3, reducing the attractive force in the left air gap magnetic fluxes G1 and G2, and increasing the attractive force in the right air gap magnetic paths G1 and G2, the rotor part 2 is It is possible to restore the original neutral state and balance the overall suction force. In this case, even if the rotor part 2 is deviated in the axial direction,
Due to the flow of magnetic flux φ ₁ and φ ₂ , the stator yoke 11,
12 and the rotor yokes 21 and 22 are restored so that their magnetic pole circumferential surfaces directly face each other. These operations are exactly the same in the Y-axis direction.

In this case, the second stator yoke 12 is provided with a constricted portion 14 and a plurality of separating portions magnetically separated from each other are provided, so that the electromagnetic coil 1
The magnetic flux φ ₂ from 6 mainly passes only through the separation parts on the X-axis and Y-axis, and rarely circulates through the stator yoke 12, so the magnetic flux φ ₂ is efficiently distributed between the stator section 1 and the rotor. It becomes possible to cause the yokes of part 2 to attract each other.

FIG. 3 is a longitudinal sectional view of the second embodiment, which differs from the previous embodiment in that the permanent magnet 23 of the rotor section 2 is not used. In this case, the first and second rotor yokes 21 and 22 of the rotor section 2
They have an integral structure connected to each other at the outside.

Functionally, the air gap magnetic path G1 is similar to the previous embodiment.
is a non-modulating gap, G2 is a modulating gap, and the magnetic flux φ ₁ emitted from the N pole of the permanent magnet 13 is transferred from the second stator yoke 12 to the second rotor yoke 22, the first rotor yoke 21, and the first stator. It returns to the S pole via the yoke 11.

Note that the permanent magnet is not in the form of an integral ring, but as shown in FIG. It may be made of non-magnetic material such as copper or aluminum. Also,
Yokes 11, 12, 21, 22 facing the air gap magnetic path
The magnetic pole is made of one tooth as shown in Figures 1 and 3, but it may also be made of multiple teeth as shown in Figure 5 to improve the rigidity in the axial direction. It is possible. Note that 24 is a non-magnetic ring for reinforcing the rotor portion 2.

Note that the constricted portion 14 of the stator yoke 12 is
Although four electromagnetic yokes 15 are provided to make the electromagnetic yokes 15 cross-shaped, the electromagnetic yokes 15 can also have three legs equally spaced and be controlled by vector ratio, and in this case, the number of constrictions 14 is three. And it is sufficient. Further, instead of this constricted portion 14, it may be completely cut magnetically.

As explained above, the radial control type magnetic bearing according to the present invention has the following effects.

(1) Since the permanent magnet is used while being magnetized in the axial direction, it is easy to manufacture the permanent magnet, and it is also easy to magnetically connect it to the yoke.

(2) The number of permanent magnets and electromagnets is small, the volume is reduced, and a flat shape can be achieved.

(3) The air gap magnetic path between the first stator yoke and the first rotor yoke is a non-modulated gap made only of permanent magnets, so the magnetic flux density can be increased.
Therefore, the rigidity in the axial direction and the rigidity around the radial axis can be increased.

[Brief explanation of drawings]

The drawings show an embodiment of a radially controlled magnetic bearing according to the present invention, with FIG. 1 being a longitudinal sectional view thereof, FIG. 2 being a plan view of the stator section and rotor section, and FIG. 3 being a longitudinal sectional view of another embodiment. FIG. 4 is a partial plan view of a modified example of the arrangement of permanent magnets, and FIG. 5 is a sectional view of the yoke. 1 is a stator part, 2 is a rotor part, 11,1
2 is a stator yoke, 13 and 23 are permanent magnets, 1
4 is a constriction, 15 is an electromagnetic yoke, 16 is an electromagnetic coil, 21 and 22 are rotor yokes, 30 and 31 are position sensors, φ ₁ and φ ₂ are magnetic fluxes, and G1 and G2 are air gap magnetic paths.

Claims (1)

[Claims] 1. Consisting of a rotor part and a stator part, each of which rotates relatively around one axis without contact with the other,
The rotor section and the stator section each have two flat annular yokes arranged in parallel, and these two rotor section yokes and two stator section yokes each have an air gap magnetic path in the radial direction. A permanent magnet magnetized in the axial direction is sandwiched between the yokes of the stator section or both of the rotor section and the stator section, and the electromagnetic yokes are connected to the electromagnetic yoke magnetically connected to the stator section yoke. A coil is provided, and one of the two air-gap magnetic paths has the magnetic flux of only the permanent magnet, and the other has the magnetic flux of both the permanent magnet and the electromagnetic coil coexisting. The attraction force acting between the rotor part and the yoke of the stator part is adjusted by the controlled attraction force by the electromagnetic coil, and the radial position of the rotor part with respect to the stator part is controlled. A radially controlled magnetic bearing featuring: 2. The radial control type magnetism according to claim 1, wherein the stator portion yoke that joins the electromagnetic yoke has at least three separation portions separated at equal angles so as to increase mutual magnetic resistance. bearing.