JPS5999118A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To enable a high-speed rotation of a rotational body only by fixing a detector in eddy current type for detecting the axial position of the rotational body regardless of the diameter of the rotational body. CONSTITUTION:An eddy current type position detector 73 is provided to detect the radial position of a cylindrical shaft 51 without any contact around the shaft 51 at a position faced to magnetic poles 64a and 64b with its sensing side faced to the peripher of a shaft 51. Eddy type position detectors 75a and 75b are provided at the lower end of the shaft 51 to detect the axial position of the shaft 51 with its sensing side faced to the lower end of the shaft 51, which is rotated by a stator 60 of an induction motor. These detectors 73, 75a, and 75b detect that the position of the shaft 51 goes off from the ideal center line of revolution, and supply electric current to the detectors for controlling the position of the shaft 51 automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic bearing device, and particularly to improvements in an attraction type magnetic bearing device.

[Ambiguous technology of invention and its problems]

Conventionally, a magnetic bearing device is known as a bearing bag w] that supports a high-speed rotating body. The magnetic bearing device a is designed to support a rotating body in a completely non-contact manner using magnetic force.
Based on the usage of magnetic force, it can be roughly divided into repulsion type and attraction type.

By the way, in the case of supporting a rotating body in a completely non-contact manner in an attraction type magnetic bearing device, it is necessary to finely control the magnetic force of each part by controlling the magnetic flux of each part.

Such control is usually performed by detecting the radial and axial positions of the rotating body and increasing or decreasing the magnetic flux at necessary locations based on this.

That is, Fig. 1 shows the suction type, and the rotor is installed at the inside (+ll) of the stator, so-called inside 1 (1).
This shows an example of a single rotor type 4+Fk air bearing device.
In the figure, 1 indicates the rotation axis, and the legs are rotation 11111 and stationary frame 3.
shows a magnetic bearing element provided between the

The magnetic bearing elements include an axial bearing element 1] and radial bearing elements 12a arranged on both sides of the axial bearing element 1.

12b. Axial bearing element zzlt1
．． A magnetic flux that is fixed to the inner surface of the stationary frame 3 and the two annular plates with high magnetic permeability attached to the outer rotation axis of the rotation axis and is magnetized to the polarity shown in the figure and generates a magnetic bearing force mainly in the axial direction. A permanent magnet 22 that is a supply source and this permanent magnet 2
The magnetic flux emitted from 2 is passed through the both sides of the annular plate 2 to 1.
The coil 24a is installed so as to be able to increase or decrease the magnetic flux passing through the magnetic poles 44', 23&, 23b, and the annular magnetic pole materials 23a, 23b.

24b. Radial bearing element 12a
+ 12b has a voluminous structure; for example, taking element j2a as an example, it includes a ring 26 made of a highly permeable material fixed to the outer periphery of the rotating shaft 1, a ring 26 fixed to the inner surface of the stationary frame 3, and A permanent magnet 27 that is magnetized with the illustrated polarity and serves as a magnetic flux supply source that generates a magnetic bearing force mainly in the radial direction, and the magnetic flux emitted from this permanent magnet 27 passes through the circumferential surface of both ends of the ring 260. Monkey-shaped magnetic pole materials 28a, 28b
and these magnetic pole materials 28a, 2. As shown in FIG. 2, it is comprised of four magnetic poles 29 protruding from the inner surface of +ib with an angular difference of, for example, 90 degrees, and coils 30 respectively wound around these magnetic poles 29. On the other hand, position 1 detectors 32 for detecting the radial position of the rotary shaft 1 are arranged on the rotary shafts at both ends of the rotary shaft 1, for example, as shown in FIG. ing. As these position detectors 32, eddy current displacement transducers are usually used. Also, at a position i6 facing toward MeJ on both end faces of the rotating shaft 10, there is a position detector 33a for detecting the axial position of the rotating shaft 1.

33b are arranged, and these detectors 33a.

33b is also generally comprised of an eddy current displacement transducer.

In this magnetic bearing device, the support is stabilized as follows. That is, when the position of the rotating shaft 1 moves in the radial direction, the gap length between the position detector 32 located in the moving direction and the rotating shaft 1 becomes smaller.
On the other hand, if the gap length between the position detector 32 located on the opposite side of the moving direction and the rotating shaft is large, as a result,
A change occurs in the output of the inner iiL detector. Utilizing this phenomenon, a control device (not shown) energizes the coil 3o wound around the magnetic pole 29 so as to reduce the magnetic flux passing through the magnetic pole 29 located in the direction where the gap length becomes smaller. In addition, the coil 3o wound around the magnetic pole 29 is energized so as to increase the magnetic flux passing through the magnetic pole 29 located in the direction where the gap length is increased, and the magnetic pole is generated by the energization. Due to the difference in magnetic force between the parts, the rotation angle is 1 degree.
; is made to move to a stable position. It should be noted that although there are various specific means of replacement, all of them basically employ the method described above. On the other hand, similarly regarding the axial direction, the position detector 3
3 m, , 93 b, and based on this, the control device controls the coil 24a.

By energizing 24b, the axial position of the rotation l1111 is moved to a stable position.

However, the conventional magnetic bearing device constructed as described above has the following problems. In other words, in order to carry out the stabilization control as described above, a position detector that detects the position of the rotating shaft 1 in the axial direction and radial direction without contacting the rotating shaft 1 is always used. As a position detector, Yuzu seeds are used, but due to the caveat of responsiveness, durability, handling environment, etc.
Exclusively eddy current displacement transducers are used. In an eddy current type position detector, in principle, it is necessary to set the area of the displacement surface to be measured to be sufficiently larger than the area of the sensitive surface of the detector.

However, 1. In the conventional device, the above-mentioned eddy current type position detectors 33a and 33b are provided facing both end surfaces of the rotating shaft 1, and the axial position of the rotating shaft 1 is detected by these position detectors 33m and 33b. Therefore, the diameter of the rotating shaft 1 must be set larger than the diameter of the sensitive surface of the position detectors 33a and 33b. There was a problem in that the diameter and weight had to be increased.

Therefore, in order to solve this problem, as shown in FIG. Position detector 33 a (;? ,? b
) may be used to detect the position in the axial direction by facing the sensitive surfaces of the two. In this way, the rotation axis l
It is possible to achieve a smaller diameter and lighter weight. but,
Since it is necessary to attach the disc 35 in a special manner, the manufacturing process can be avoided, and when taking into account the central stress applied to the attachment part of the disc 35, it is not possible to increase the number of rotations. Have difficulty.

The above explanation was an example of an inner rotor type, but an outer rotor type can also be used if the hollow rotating shaft 1a has a sufficiently thin wall thickness as shown in Fig. 5. In this case, a conductive annular plate 36 is attached to the inner or outer surface of the rotating shaft 1a, and a position detector 33a (33b) is arranged with the sensitive surface facing the axial surface of the annular plate 36. The stationary pillar 37
By supporting the rotating shaft 1a, the axial position of the rotating shaft 1a is detected. For this reason, there was an unavoidable problem similar to the above-mentioned inconvenience.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to change the axial position of the rotating body without affecting the diameter of the rotating body, and in addition, to change the position of the rotating body in an exceptional manner. To provide a magnetic bearing device that is equipped with a detection system that detects well without attaching a measuring member or just by attaching a measuring member of a sufficiently small diameter, and thereby enables the realization of high-speed rotation. It is in.

The magnetic bearing device according to the present invention detects the axial position of the rotating body by arranging a position detector for detecting the axial position so that its sensitive surface is parallel to the outer peripheral surface of the rotating body. It is characterized by what it did. That is, to describe it in more detail, as shown in FIG.
,>x,2 ,X2≧0), the ideal center of rotation of the rotating body R is located at the boundary position where Boundary fr drawn perpendicular to S
At least one pair of position detection is made by intersecting the sensing IC surface P with respect to UT, and facing the rotating body R in opposite directions with the sensing surface Pf: the ideal rotation center line S as the center. The axial position of the rotating body R is detected using the detectors E1 and E2.

〔Effect of the invention〕

With the arrangement of the position detector EIIE as described above 4),
For example, taking the position detector E1 as an example, a part of the sensitive surface of the position detector El faces the circumferential surface of the large-diameter X1 portion of the rotating body R, and the remaining portion faces the circumferential surface of the small-diameter X2 portion. This means that they are facing each other. Since the distance between the sensitive surface P and the circumferential surface of the X1 section is narrower than the distance between the circumferential surface of the X2 section, the output of the position detector E1 is It depends on the width H. Therefore, the rotating body R is the sixth
When displaced in the direction of the solid line arrow Y in the figure, the shield width H changes,
Position detector E! The axial position of the rotating body R can be detected from the output of the position detector E without any change in the output of the position detector E. However, the output of the position detector E1 depends on the gap length gl between the position detector E1 and the rotating body R. However, if the position detectors gt and g2 are arranged symmetrically around the ideal rotation center line S as in this invention, the position detector E
The output due to the gap length gleg11 included in the output of 1+E2 can be easily erased by electrical circuit processing,
It is possible to obtain an output that corresponds only to displacement in the axial direction.

In this case, the position in the axial direction can be detected using a portion of the rotating body R where the outside diameter changes suddenly, such as a stepped portion or an end. It is sufficient to attach only small-diameter members without having to attach them, or even if they are attached, it is sufficient to attach only small-diameter members. Therefore, the axial position can be detected without increasing the diameter or weight of the rotating body, and without giving special consideration to centrifugal stress, and as a result, high-speed rotation can be achieved. can contribute to the realization of

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 shows an example in which the present invention is applied to a magnetic bearing device of a suction type and external rotation type.

That is, in the figure, 51f indicates a hollow rotating shaft, and 51f indicates a magnetic support element provided between the inner surface of the rotating shaft 5 and the stationary portion 53.

The rotating shaft 5 is 4. It is formed into a cylindrical shape from a magnetic non-magnetic material or a paramagnetic material.

The 4jR air support element 52 is composed of a rotating element 54 and a stationary element 55. The rotating 1nIl element 54 is formed with a two-stage structure in the axial direction on the inner circumferential surface of the rotating shaft 5.
Ring 6 made of high magnetic permeability fiber installed inside 61&, 6Ib
2m, 62b. On the other hand, the stationary side element 55 includes a cylindrical yoke 63 mounted coaxially with the ideal rotation center line of the rotating shaft 5, and a cylindrical yoke 63 protruding from the outer periphery of both ends of the yoke 63 with an angle difference of 90 degrees. magnetic poles 64m and 64b for radial support, and coils 65 for radial support force control wound around these magnetic poles 64h and 64b, respectively.
a, 65b, an annular magnetic pole 66 for axial support protruding in an annular shape from the outer periphery of the central part of the yoke 63, and an annular magnetic pole 66 for axial support force control attached to both sides of the annular magnetic pole 66 on the outer periphery of the yoke 63. The coils 67m and 67b and the annular magnetic pole 6 are formed on the outer periphery of the yoke 63.
It is composed of annular permanent magnets 68a and 68b that are attached to both sides of the magnet 6 and magnetized to the polarities shown in the drawing. The yoke 63 is fixed to the stationary part 53 via the support part $Avo, the induction motor yoke 7 and the support member 72.

Therefore, with 5 rotations of the rotation axis, and 64 m of magnetic poles, 64
At positions facing b, there are eddy current position detectors 73 for non-contact detection of the radial position of the rotating shaft 5, each with its sensitive surface facing the outer peripheral surface of the rotating shaft 5. These position detectors 73 are supported by a stationary frame 74 via the support side. Further, at both rotated positions, there are eddy current type position detectors 75a for detecting the axial position of the rotating shaft 5.

As shown in FIG. 8, the position detectors 75b are arranged so that a portion of each sensitive surface faces the outer circumferential surface of the lower end of the rotating shaft 5, and the sensitive surfaces face each other.
a*75b is also supported by the stationary frame 74 via a support member. In the figure, 80 indicates a stator of a motor that applies rotational power to the rotating shaft 5, and 8 indicates a rotor of the same motor.

The output end of the position detector 73 is connected to a known radial stabilization control device (not shown) that stabilizes the radial direction by energizing the coils 65m and 65b based on the outputs of the position detector 23. It is connected to the. Also,
The output ends of the position detectors 75m and 75b are connected to the coil 67a.
.

It is connected via a signal processing circuit 82 shown in FIG. 10 to a known axial stabilization control device (not shown) which stabilizes the axial direction by energizing the motor 67b. The signal processing circuit 82 converts the outputs of the position detectors 75a and 75b into the converter 8.
．． 1a, l13b linearize and amplify the offset voltage of the amplification No. 43, bias power supply 114th,
84b's output voltage is applied, and both position signals from which the offset voltage has been erased are applied to the Kaga-
After the signals are added in an amplifier 86 and further amplified by an amplifier 88 via a logarithmic amplifier 87 as necessary, the signals are introduced into the known axial stabilization control device mentioned above.

With such a configuration, the magnetic flux emitted from the N pole of the permanent magnet 68a reaches the ring 62th, and then reaches the ring 62th.
passing axially through a, on the one hand a ring 62a;
From the inner surface of the magnetic pole 64a.

It passes through the yoke 63 and reaches the south pole, and on the other hand, it passes from the end face of the ring 62m through the annular magnetic pole 66 and the yoke 63 to reach the south pole. N of permanent magnet 68b
The magnetic flux emitted from the poles similarly passes through two paths. Therefore, the inner surfaces of the rings 62h, 62b and the magnetic poles 64m, 64
A radial magnetic bearing force acts between the rings 62h and 62b, and an axial magnetic bearing force acts between the annular magnetic pole 66 and the end faces of the rings 62h and 62b. At this time,
When the rotary shaft 5 attempts to move in the radial direction, this movement is detected by the position detector 73, which activates the radial stabilization control device to appropriately bias the coils 65a and 65b to stabilize each part. by controlling the radial magnetic bearing force of the rotating shaft 5.
ml until stable. On the other hand, when the rotating shaft 5 is about to move in the axial direction, the axial stabilization control device is activated and the coil 67a is activated.

67b is appropriately biased and the axial magnetic bearing force is controlled to move the rotating shaft 5 to a stable position in the axial direction. That is,
When the rotating shaft 51 is displaced in the axial direction, the outer peripheral surface of the rotating shaft 51 and the position detector 75a.

Since the width υ between the sensor 75b and the sensitive surface changes, the outputs of the position detectors 75m and 75b also change.

This output also depends on the gap length g between the sensitive surface and the outer peripheral surface of the rotating shaft 5. For example, if we focus on the output of one position detector, it changes as shown in FIG. 9 depending on the axial displacement of the rotating shaft 51. In the figure, J indicates when g is large, K indicates when g is moderately windy, and L indicates when g is small. In any case, when the rotating shaft 5 is displaced in the axial direction, the position detector 75a.

The output of 715b changes. This output is signal processing circuit 8
After being linearized by the converters 83m and 83b of 2, it is converted into a signal with the offset a pressure eliminated by the bias power supply &4th, 1J4b. Both signals are then added by an adder 86.

The gap lengths between the sensitive surfaces of the position detectors 75m and 75b and the rotating shaft 51 are such that when one becomes larger, the other becomes smaller, so the output of the adder 86 does not include the component due to the gap length, and the rotational This corresponds only to the axial displacement of the shaft 5. The axial stabilization control device then uses the coils 67a and 67 based on the output signal of the signal processing circuit 82.
7b is energized. Therefore, the rotating shaft 5 moves to a stable position in the axial direction, and a completely non-contact magnetic support state is realized here. Note that if the induction motor is energized in this state, the rotating shaft 5 can be rotated in a completely non-contact state.

In this case, a portion of the sensitive surface faces the outer surface of the rotating shaft 5, where the outer diameter is steep, or in the case of this embodiment, the outer surface of the end of the rotating shaft 5. Similarly, position detectors 75m and 75b are installed, and position detectors 75m and 75b are installed.
75b is used to detect the axial position of the rotating shaft 5, the axial position detection thread can be used without adding any special member to the rotating shaft 5 to detect the axial position. can be achieved. Therefore, it is possible to prevent the rotational speed from increasing in size or becoming too heavy, and there is no need to consider centrifugal stress resistance, so that the above-mentioned effects can be obtained after all.

Note that the present invention is not limited to the actual Mn example described above. That is, in the above embodiment, a current type displacement transducer is used as a position detector, but a previous generation capacitance type displacement transducer may also be used. Further, in the above-described embodiment, the position detectors 75a and 75b for detecting the axial position are arranged outside the hollow rotating shaft 5, but they may be arranged inside. Further, although the above-described embodiment is an example in which the present invention is applied to an outer rotor type magnetic bearing, the present invention can of course be applied to an inner 1111 rotor type magnetic bearing.

Figure 11 shows an example in which the present invention is applied to a 5-axis control type rotor type rotor.

It shows. Note that a member for supporting the stationary element is omitted in the figure. That is, in the figure, 101 indicates a rotating shaft, and this rotating shaft 10 is supported in the axial direction by axial bearing elements (02 a + 102b) at both ends thereof, and by a radial bearing element (j03*) at its central portion.

103b supports in the radial direction. The axial support elements 102m and 102b are configured equally, and taking the element 102m as an example, the rotation axis 101
An annular plate 104 made of a high magnetic permeability material is fixed to the outer periphery of the end of the annular plate 104, a permanent magnet 105 is fixed to the stationary part, and the magnetic flux emitted from the permanent magnet 105 is transferred to the periphery of one side of the annular plate 104. 706 m of magnetic poles.

106b and: these magnetic 4'4i 106 m, 1
It is composed of coils 107m and 107b for axial support force control, which are wound around the outer circumference of the coil 06b. On the other hand, the radial bearing elements 103a, 10, and ``jb'' are also configured in blue. Taking element 103b as an example, it is made of high magnetic permeability material fixed to the outer periphery of the rotation IIIll and θ. Ring 108 and annular permanent magnet 1 fixed to the stationary part
09, and the magnetic flux emitted from this permanent magnet 109 is transferred to the ring 10.
80 Magnetic pole material 11o passed through the outer peripheral surface of both ends
a, 1Job and these magnetic pole interests' 1 j Oa,
The magnetic poles 11 protrude from the inner surface of I J Ob with an angular difference of 90 degrees, and the radial bearing force iii! is wrapped around the outer circumference of these magnetic poles 111! It is composed of a coil 112 for use by J.

In addition, at the positions corresponding to the respective magnetic poles 111 on both ends of the rotary shaft 1010, eddy current position detectors 113 for detecting the position in the radial direction of the rotary shaft 1010 are placed on the sensitive surface of the rotary shaft 10. is arranged facing the outer circumferential surface of.

Further, on the radial side of the annular plate 104 forming the axial support element 102b'Ir:s, there is an eddy current type position detector 114m for detecting the axial position of the rotating shaft 1.

114b has a part of its sensitive surface facing the outer circumferential surface of the annular plate 104, and is arranged symmetrically about the ideal rotation center line. The output of the position detector 113 is then introduced into a known radial control device, and a position detector 114m.

The output of 114b is introduced into a known axial control device via a signal processing circuit shown in FIG. Note that 120 in the figure indicates an induction motor for applying rotational power to the rotating shaft 101.

Even with this configuration, the position detector 114m
, 114b in the above-mentioned relationship, it is possible to detect the axial position without providing several special members for detecting the axial position on the rotating shaft 10, as is clear from the above explanation. I can do it. Therefore, the same effects as in the embodiment described above can be obtained.

7. In the above embodiment, the axial support g 7
'+7: The annular plate 104 constituting z b is used to detect the position in the axial direction, but as shown in the 121st MI, a conductive ring 131 is placed around the outer circumference of the rotating shaft 10
The ring 13 may be used to detect the position of the shaft opening. In this case, the position detector 114
Since the rings 114b and 114b are provided in the above-mentioned relationship, the axial position can be detected satisfactorily even if the wall thickness of the ring 13 is the same as that of the political tone. Therefore, by providing the ring 13, there is no risk that the rotating body will become larger or larger. The position can be detected well. Of course, the present invention can also be applied to other types of magnetic bearing devices.

[Brief explanation of the drawing]

Figure 1 is a schematic vertical cross-sectional view of a conventional magnetic bearing device, Figure 2 is a cross-sectional view of the same device taken along line A-A in Figure 1 and viewed in the direction of the arrow, and Figure 3 is a cross-sectional view of the same device. B- in Figure 1
A sectional view taken along line B and viewed in the direction of the arrow, FIGS. 4 and 5 are diagrams for explaining different installations of the axial position detector, and FIG. 6 is a magnetic bearing according to the present invention. FIG. 7 is a longitudinal sectional view of a main part of a magnetic bearing device according to an embodiment of the present invention; FIG.
The figure is a diagram for explaining the arrangement of the axial position detectors in the device, Figure 9 is a diagram for explaining the output characteristics of the axial position detector, and Figure 10 is the output of the axial position detector. FIG. 11 is a schematic vertical sectional view of the main part of a magnetic bearing device according to another embodiment of the present invention, and FIG. 12 is a diagram of a magnetic bearing according to still another embodiment of the present invention. FIG. 3 is a side view of the main parts of the device. 5 No. Rotating shaft, 52 Magnetic bearing element, 73°113 Radial position detector, 76 a, 7
5b. 114m, 114b... Axial position detector. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Clause 3 Figure 4 Figure 33a (33b) Figure 5 Figure 7 Figure 8 Figure 9 Axial direction of the rotation axis No. 10 Giant 1

Claims (1)

[Scope of Claims] (2) A 4m pneumatic support element that supports a rotating body in a non-contact manner by magnetic force, and a device that detects the radial and axial positions of the rotating body without contacting the rotating body. j■“
In a magnetic bearing device comprising a detection system and means for controlling a radial magnetic bearing force and an axial magnetic bearing force of the magnetic bearing element based on outputs of the position detection system, the axial position is detected. In the position detection system, the outer diameter or inner diameter of the rotating body may be Xl or X2 (however, X 1 >
The sensitive surfaces are made to intersect with the boundary line drawn orthogonally to the filling rotation center line of the rotating body at the boundary position 16 that changes to X 2 1 A magnetic bearing device characterized in that it is mainly constructed of at least a pair of position detectors facing the rotating body in opposite directions about a center line. (2) The magnetic bearing according to claim 1, wherein the position detector is any one of an optical displacement transducer, a capacitive displacement transducer, and an eddy current displacement transducer. Device.