JPH0788850B2 - Magnetic levitation slide - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic levitation slide for use in linear motion bearings of a spectroscopic device such as a linear motion system, a non-contact transfer system, and other positioning tables. .

[Conventional technology]

In general, the motion of a rigid body in space has three degrees of freedom related to translational motion of the center of gravity and three degrees of freedom related to rotational motion around the center of gravity with respect to a columnar model as shown in FIG.

In other words, in the case of a normal magnetic bearing spindle, it can be said that the movement "L" of the rotating body around the rotation axis, that is, the five degrees of freedom excluding rolling is supported by some magnetic force. In the magnetic levitation slide to which the present invention is related, the objective is achieved by controlling the five degrees of freedom other than the moving direction of the movable body. That is, the Z-axis direction in FIG. 15 is not controlled, but instead the "L" motion and the remaining degree of freedom are controlled.

By the way, in recent years, various magnetic bearing systems have been developed, and their applications as non-contact bearings have been expanded. The magnetic levitation slide is one of them, and the use of the above-mentioned system is considered especially for a transport system and the like.

As shown in FIGS. 16 and 17, a conventional magnetic levitation slide has a horseshoe-shaped electromagnet M ₁ , M ₂ , M ₃ , M at the bottom of a movable table 11 formed so as to surround an I-shaped rail. ₄ are arranged at the four corners, and the movable system 11 table is levitated by its reaction by attracting the stationary rail 12 side with this electromagnet, thereby realizing non-contact support. That is, at least three (four in the figure) sensors 14 installed near the four electromagnets detect the distance δ from the rail 12, and the value of δ is always constant (usually 0.1 to 0.4 m).
An external control circuit or a control circuit built in the movable body 11 controls the exciting current flowing through the electromagnets M _{1 to} M ₄ so as to keep m).

For example, for the pitching movement of the movable body table 11 shown in FIG. 18, in the steady state, the electromagnets M _{1 to} M ₄ which generate attraction forces of 1/4 of the table weight M respectively,
Currents I ₁ and I ₂ flowing in ₁ and M ₂ are increased, while electromagnets M ₃ and I ₂ are increased.
The pitching motion is attenuated by reducing the currents I ₃ and I ₄ flowing through M ₄ to maintain the fixed position.

For the rolling motion shown in Fig. 19, the electromagnet
The currents I ₁ and I ₃ of M ₁ and M ₃ are increased, and the currents I ₂ and I _{4 of the} electromagnets M ₂ and M ₄ are increased.
Can be returned to the normal position by reducing.

[Problems to be solved by the invention]

However, for the yawing motion shown in FIG. 20, the motion control is not performed in the electromagnet arrangement,
There is generally no other way than by a passive restoring force by trying to minimize the magnetic energy potential at the electromagnet air gear (which acts to minimize the magnetic reluctance).

This restoring force F _P is due to the magnetic field lines (hatched portion) shown in FIG. 21, and generally only a force of 1/10 or less acts on F _X.

Therefore, to maintain the position of the movable member table accurately relative yawing motion, as FIG. 22, four electromagnets (M ₅ ~M ₈₎ and at least two sensors (S _5, S ₆₎ You have to add more.

In other words, this method requires a total of 8 electromagnets and a minimum of 5 (6 in the figure) sensors. That is, at least 3 inputs (4 inputs in the figure) and 4 outputs for pitching and rolling, and 2 inputs (4 inputs) and 4 outputs for yawing are required.

Further, in this method, the electromagnets M _{1 to} M ₄ must always generate a suction force that is in balance with the table's own weight (including the weight of other instruments, objects, etc. if they are on the table). In addition, the sensor detection surface that affects the positioning accuracy of the table needs to be subjected to a surface grinding process that reduces the surface roughness from the left and right and up and down directions of the rail, and the suction surface of each electromagnet is also finished accurately. However, there is a disadvantage in that the quality of these processings is likely to affect the control performance of pitching, rolling, and yawing, which makes the apparatus expensive.

INDUSTRIAL APPLICABILITY The present invention improves the control performance for yawing and pitching, and is a magnetic levitation slide used for linear motion bearings of a spectroscopic device such as a linear motion system, a non-contact transfer system and other positioning tables, which is easy to manufacture and inexpensive. Is intended to provide.

[Means and Actions for Solving Problems]

According to the present invention, in the control type magnetic slide, the guide rails are cylindrical guide rails, and the electromagnets are motor-shaped electromagnets concentric with the cylindrical guide rails. Pitching and yawing on the table can be easily controlled.

Further, by arranging the control axis of the electromagnet for controlling the pitching and yawing of the table at an angle of 45 ° with respect to the gravity direction, the magnetic force can be effectively used for the supporting force of the table or the like.

Further, by providing the table with two or more repulsive permanent magnets or controlled magnetic bearings, the rolling motion of the table can be easily controlled.

Also, by providing a rectangular convex portion in the center of the lower surface of the movable body table, the resistance against rolling motion is increased,
Stability can be improved.

Further, by providing a repulsive permanent magnet or a controlled magnetic bearing on the convex portion, rolling control becomes effective.

Further, by providing magnetic poles independent of each other on the guide rail, the control of rolling becomes more effective.

Further, by providing the unevenness on the magnetic pole surface, the control of rolling becomes more and more effective.

When a rare earth cobalt-based permanent magnet is used as the permanent magnet, the magnetic force becomes strong, which is advantageous for control.

〔Example〕

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

FIG. 1 shows the appearance of the first embodiment, and FIG. 2 shows a sectional view taken along a plane perpendicular to the moving direction.

In the slide 1 of this embodiment, a columnar rail 4 penetrates through the center of a movable body table 2 that moves parallel to a base 3, and an 8-pole core and four electromagnets M facing the rail 4 are provided. _There are two magnetic levitation mechanisms formed by _X , M _Y , M _X ′ and M _Y ′ in the moving direction. Each of the electromagnets forms a magnetic closed loop circuit as shown by a broken line in FIG. 2 with the rail 4, and the table 2 itself is moved from the base by generating an attractive force to the stationary rail 4. Can rise up.

At this time, the control axes X and Y of these 8-pole cores are arranged at an angle of 45 ° with respect to the direction of gravity. By arranging the electromagnets in this way, the electromagnets M _X , M _Y, and M
_The currents flowing through _X ′ and M _Y ′ are balanced.

The reason is that the angle α between the direction of gravity and each control axis is α ≠
At 45 °, the currents flowing through M _X ′ and M _Y ′ and M _X and M _Y become unbalanced, which places a heavy burden on either coil and coil drive circuit, and This may cause a decrease in life and reliability.
Therefore, in the yawing and pitching motion control electromagnets of the magnetic levitation slide, it is best to set α = 45 °.

That is, the means used in the "radial electromagnet for horizontal magnetic bearing" found in Japanese Patent Laid-Open No. 58-81216 is applied.

The yawing and pitching motion control electromagnet having the above characteristics is mounted on the table side, and the radial air gear gap with the rail is usually about 0.2 to 0.5 mm.

In the case of DC excitation, unlike a magnetic bearing stator of a magnetic bearing spindle having a normal rotor, this electromagnet uses almost no eddy current loss and hysteresis loss. Since the above loss occurs, it is necessary to suppress the loss by forming a laminated structure of silicon steel plates having a thickness of about 0.35 to 0.50 mm.

It goes without saying that the structure on the rail 4 side is also the same.
The yawing and pitching motion control electromagnets have 8 poles,
It is composed of multiples of 4 such as 12 poles and 16 poles. For the rolling motion, which is one degree of freedom of the remaining table, two pairs of facing permanent magnet magnetic bearings 5 and 5'are arranged on the base 3 and the lower surface of the table 2 to passively control the rolling motion with a repulsive force. It is becoming like this.

At this time, the repulsive force by the permanent magnets 5 and 5'also contributes to the levitation force of the table itself, which has the advantage of increasing the load capacity in the gravity direction of the entire magnetic levitation slide.

Further, as the permanent magnets 5 and 5'are installed farther from the center of the rail 4, the rotation moment for controlling the rolling motion of the rotary shaft of the table 2 can be increased, and the resistance against the rolling motion is stable. The placement is obtained.

The permanent magnet 5 on the table side is determined by its own weight of the table 2 and the load condition applied to the table. However, as shown in FIG. As shown in FIG. B, it can be provided in a part, for example, at four corners. Since this permanent magnet controls the rolling motion in principle, the objective can be achieved if it is installed in a place near the side surface of the movable table where a large rotational moment can be obtained. Since it also contributes to the levitation force, it is preferable to install it so that the center of gravity G of the table is located at the intersection of the diagonal lines of each permanent magnet group.

On the other hand, the permanent magnet on the side of the base 3 is installed as shown in FIG. 4, but the installation position is partially set depending on the moving distance of the table 2, and the present invention is not limited to this embodiment.

It is needless to say that two or more rows of N-S-N-S may be arranged, and such an arrangement is also consistent with the object of the present invention.

However, when the table of FIG. 3b and the base of FIG. 4 are used in combination, the table 2 does not face the permanent magnets 5 on the table 2 side unless the bottom surface of the table 2 is made of a non-magnetic material. Be careful because it will be attracted to the permanent magnet 5 '.

In this embodiment, the position detecting sensors S _{1 to} S ₈ are arranged facing the cylindrical rail 4 in the circumferential direction and in the control axis direction, as shown in FIG.

That is, the sensors S _{1 to} S ₄ are required to control one electromagnet for yawing and pitching control, and at least two electromagnets for yawing and pitching control are required as a whole, so S _{1 to} S ₈ A total of 8 sensors are required. However, when the sensor output is not differentially calculated by XX ′ and the temperature drift of the sensor can be ignored,
For example, four sensors S ₁ , S ₂ , S ₅ , and S ₆ can sufficiently function. The above may be considered to be similar to that of a normal magnetic bearing spindle.

At this time, the sensor detection surface is the surface of the cylindrical rail 4, but there is an advantage that accuracy can be easily obtained by polishing by supporting the center of the rail, as compared with surface grinding at two or more points of the magnetic levitation slide in FIG. .

It is also possible to form the sensor by an inductance detection type in which windings are laminated on a laminated silicon steel plate or an eddy current type (or a wire cutter, an electric discharge machining integrated metal).

Next, FIG. 6 shows another embodiment.

This embodiment further includes a pair of electromagnets M _L , M _L , for the rolling motion control, as compared to the embodiments of FIGS. 1 and 2.
This is an extension of M _L ′, and a sensor S ₉ is installed to control this electromagnet.

The position of the sensor S ₉ makes it easier to detect rolling motion.
Naturally, it is better to be farther than the cylindrical rail. Further, in this embodiment, the permanent magnet 5 and the electromagnet M are arranged from the center of the rail.
_L (M _L ′) and sensor S ₉ are arranged in this order, but electromagnet M _L
(M _L ′), the permanent magnet 5, and the sensor S ₉ may be arranged in this order. This electromagnet M _L (M _L ′) controls the rolling motion, but since the table 2 is completely in the levitating state, the electromagnet M _L actually occurs even when rolling occurs.
_Since the attraction force of _L (M _L ′) returns to a fixed position even if it is considerably small, this electromagnet M _L (M _L ′) generally does not cause an excessive load on the yawing and pitching control electromagnets. In this case, the table-side attraction surface of the electromagnet M _L (M _L ′) is naturally made of a ferromagnetic material only at that location.

In the embodiment shown in FIGS. 2 and 6, the opposing surfaces of the base and the table can be formed as one flat surface, so that there is also an advantage that the electromagnet attraction surface, the permanent magnet surface, and the sensor detection surface can be finished by surface grinding at the same time.

When the load becomes excessive, the electromagnets M _L and M _L ′ can be installed so as to face the rising portion 3 ′ of the base 3 as shown in FIG. 7, and as shown in FIG. It can also be configured so as to be sandwiched in a 3'-shape.

FIG. 9 shows another embodiment, in which the movable body table 2 has a rectangular convex portion 2'on the lower surface and in the direction of gravity, while the base 3 also has a concave portion 3 ". In this case, the center of gravity of the original movable body table 2 shifts from G'to G. However, due to the yawing and pitching motion control electromagnets, the movable body table 2 is positioned so that the center position of the inner diameter of the electromagnet becomes the center of the cylindrical rail. Since they are held in coincidence, the center of the rolling movement is equal to the electromagnet inner diameter center G '.

At this time, even if an external force is applied to the table 2 to generate a rolling motion, the moment of inertia about the G'axis is obviously increased, so that the angular acceleration of the rolling motion can be reduced. That is, the rolling motion can be easily controlled with a small control output.

Further, as shown in FIG. 10, by providing a convex portion 2'under the movable table, the weight is increased, and the opposing repulsive permanent magnets 6, 6'are provided with concave portions of the convex lower surface 2'and the base 3. It is placed in the portion 3 "to reduce the load. Further, the concave portion 3" of the base 3 facing the side surface of the convex portion 2'is provided with permanent magnets 7 and 7'to positively control the rolling motion. I am doing it.

That is, since the rolling motion control force is generated in the convex portion 2'having a long working distance from the center of gravity G ', there is an advantage that a control effect having a larger moment can be obtained. It is of course possible to form these permanent magnets 6,6 ', 7,7' by control type electromagnets 7 "as shown in FIG. 11, and the effect is as already described. A sensor S ₁₀ is provided.

Next, according to the present invention, in order to further improve the control effect of the electromagnet and improve the stability against rolling,
Improvements have also been made to the electromagnet itself. Less than,
This point will be described.

In FIG. 12, the rail 4 is provided with the movable body table 2 and eight pairs of electromagnets provided on the rail 4. That is, the magnetic pole 8 is formed on the table 2 side, and the magnetic poles 8'which are independent of each other are also formed on the rail 4.

When the movable body table 2 is levitated, a magnetic closed loop shown by a broken line is formed between the magnetic poles 8 and 8 '. Therefore,
The magnetic flux flowing in the magnetic circuit is controlled by changing the exciting current, and the magnetic class attractive force generated by the magnetic flux energy is changed to hold the table 2 at a predetermined position. However, when the table 2 causes a rolling motion around the intersection of the X-X 'and Y-Y' axes, the opposing magnetic poles are displaced. At this time, the magnetic flux changes, but at the same time, a restoring force that restores the deviation works. Since this restoring force acts in a direction to reduce the rolling motion, the rolling motion is passively controlled.

Similar effects occur in FIG. A non-magnetic member 9 is fitted between the magnetic poles 8 ′ of the rail 4. Further, since the end faces of the magnetic poles are formed in a concavo-convex shape, and the deviation with respect to the rolling motion is large, the restoring force is further increased.

Incidentally, yawing as shown in FIG. 14, when the control of Pitsuchingu movement, when utilizing the rail surface as the detection surface of the sensor for obtaining the control signal, the non-magnetic material, the sensor S ₁ to S ₄ It is enough to have only four facing ones. When the magnetic poles are formed on the rail 4, the shape becomes complicated, so that it is advantageous to use a laminated structure of silicon steel plates.

In addition, these permanent magnets are made of BH such as samarium and cobalt.
The rare-earth cobalt-based magnet having a large product is advantageous because a strong magnetic force can be obtained.

〔The invention's effect〕

With the above-described configuration, the present invention has the following effects. That is, 1. The conventional magnetic levitation slide requires at least 5 sensors, while 4 (Fig. 5) sensors are sufficient (5 in Fig. 6).

2. In addition, the sensing surface of the sensor and the attraction surface of the yawing / pitching control electromagnet are formed as cylindrical surfaces, which facilitates manufacturing.

3. Since the permanent magnet is used for rolling motion control, the load capacity in the gravity direction can be increased.

4. Furthermore, only instead of simply supported by the balance of gravity, if used by passing a constant electric current electromagnets M _X, the M _Y, electromagnets M _X ', M _Y' even steady-state current flowing through the increase Then
Therefore, high rigidity can be realized against yawing and pitching.

5. If the center of the rail is selected at the same position as the center of gravity of the table, the table can freely rotate with respect to the center of the rail, so if you want to completely control the yawing and pitching motions, you can separate only the rolling motion. Since the rolling motion can be controlled and can be easily controlled by the simple structure as described above, the rolling motion can be configured without complicating the entire control system.

6. Since the movable body table is provided with a convex portion below it, a large moment of inertia around the center of the yawing and pitching control axes of the table can be taken, and the control for the remaining rolling movement becomes easy. The rolling motion can be controlled with a small force. Further, by providing the sensor at the tip of the convex portion, the sensitivity of the sensor is increased, and there is an advantage that the stability of control of rolling motion is improved.

7. Restoring force can be further increased by making the magnetic poles on the rail side independent. In addition, the effect is further enhanced by providing irregularities on the magnetic pole surface.

And so on.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention. FIG. 2 is a cross-sectional side view of the same. 3a and 3b are bottom views of the table showing the arrangement of rolling control permanent magnets. Similarly, FIG. 4 is a top view of the base. FIG. 5 is a cross-sectional view of an embodiment of the present invention showing the arrangement of sensors. 6 to 8 are transverse cross-sectional views of an embodiment of the present invention including a permanent magnet or a control type electromagnet for rolling control. Figures 9-
FIG. 11 is a cross-sectional view of an embodiment in which a convex portion on the lower surface of the table for rolling control and a permanent magnet or a control type electromagnet are provided on the convex portion and the base. FIG. 12 is a cross-sectional view of an embodiment in which the guide rail has a structure for rolling control. FIG. 13 is a partially enlarged view of the magnetic pole structure which has been further improved. Figure 14 shows
13 is a cross-sectional view showing a modification of FIG. FIG. 15 is a perspective view of a columnar model for explaining the movement of a rigid body. FIG. 16 is a cross-sectional view of a conventional device. FIG. 17 is a perspective view of the device shown in FIG. FIG. 18 is a vertical cross-sectional view for explaining a method for controlling the pitching of the movable body table. FIG. 19 is a cross-sectional view for explaining a rolling control method of the movable body table. FIG. 20 is a plan view for explaining the yawing motion of the movable body table. FIG. 21 is a partial cross-sectional view of the movable body table for explaining the yawing control action of the electromagnet. FIG. 22 is a perspective view of a movable body table provided with a complicated yawing control device. 1 ... slide, 2 ... table, 2 '... convex part, 3 ...
... Base, 3 '... Rise of base, 3 "... Concave part of base, 4 ... Rail, 5,5' ... Permanent magnet,
6,6 ′, 7,7 ′ …… Permanent magnet, 7 ″ …… Magnetic bearing, 8,8 ′…
... magnetic pole, 9 ... non-magnetic material

Claims (9)

[Claims] 1. A guide rail attached to a fixing member,
The movable table is provided with an electromagnet having an adjustable attracting force and moves along the guide rail. The attracting force of the electromagnet is adjusted to control the relative position between the table and the guide rail. In the controlled magnetic levitation slide, the guide rails are cylindrical guide rails that penetrate the table, and the electromagnets are installed apart from each other in the moving direction of the table, and each of the two or more controls the pitching and yawing. It is a motor-shaped electromagnet concentric with the cylindrical guide rail, and a plurality of permanent magnets of the same polarity are arranged facing each other on the facing surfaces of the table and the fixing member to control the rolling motion of the table. Characteristic magnetic levitation slide. 2. The magnetic levitation slide according to claim 1, wherein the pitching and yawing control electromagnets are arranged such that the control axis direction is inclined at 45 ° with respect to the gravity direction. 3. The magnetic levitation slide according to claim 1, wherein the table further comprises a pair of active rolling motion control electromagnets. 4. The magnetic levitation slide according to claim 1, wherein the movable body table has a rectangular convex portion at the center of its lower surface to increase the moment of inertia about the center of gravity. 5. The magnetic levitation slide according to claim 4, wherein the rectangular convex portion is provided with a repulsive permanent magnet that controls rolling motion. 6. The magnetic levitation slide according to claim 5, wherein the rectangular convex portion further comprises an electromagnet for active rolling motion control. 7. A magnetic levitation slide according to claim 1, wherein said guide rail comprises magnetic poles cooperating with an adjustable electromagnet of said movable body table. 8. The magnetic levitation slide according to claim 7, wherein a large number of concaves and convexes are formed on the surfaces of the guide rails and the magnetic poles of the movable body table that face each other. 9. The magnetic levitation slide according to claim 1, wherein the permanent magnet is a rare earth cobalt-based permanent magnet.