JPH0741992B2 - Magnetic levitation carrier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation transfer device, and more particularly to a magnetic levitation transfer device installed in a semiconductor manufacturing factory or the like.

[0002]

2. Description of the Related Art With the recent progress in semiconductor manufacturing standards, miniaturization of VLSI device patterns has progressed further, and there has been a strong demand for extremely clean vacuum manufacturing equipment. Particularly, in the DRAM manufacturing process of 16 Mbits or more, it is absolutely necessary that it is dust-free. However, in manufacturing equipment where linear transport is essential,
It is very difficult to prevent the generation of dust due to friction and wear.

On the other hand, since the magnetic levitation transfer device is supported by magnetic force in a non-contact manner, no dust is generated and no lubricating medium is required. For this reason, it has been attracting attention as a conveyance device having an extremely high degree of cleanliness.

FIG. 5 is a vertical sectional view of a conventional magnetic levitation transport device. With reference to FIG. 5, the mover 17 travels while levitating on the rail 20. The mover 17 includes a plurality of levitation electromagnets 2 provided so as to face the left and right lower surfaces of the rail 20.
3, a plurality of displacement sensors 21 for detecting gaps between the rails 20, a plurality of guiding electromagnets 19 provided so as to face the side surfaces of the rails 20, and a levitation electromagnet by the output of a guiding displacement sensor (not shown). A control circuit 18 for feedback-controlling 23 and the guiding electromagnet 19 and a battery 22 are included.

In the conventional magnetic levitation transporting device constructed as described above, the moving member 17 is guided by the guiding electromagnet 19 while being levitated on the rail 20 by the levitation electromagnet 23, and traveled by a linear motor (not shown).

However, in the conventional magnetic levitation transfer device shown in FIG. 5, the levitation electromagnet 23 is made of laminated silicon steel plates, and polymer materials such as molding materials and cords are exposed to the outside of the device. Therefore, contamination due to gas release becomes a problem in high vacuum. Further, since the electronic circuit that constitutes the control circuit 18, the battery 22, and the like are mounted, there is a problem that the baking necessary for obtaining a high vacuum cannot be endured.

Therefore, in order to solve the above problems,
All the gas generating sources such as the levitation electromagnet 23, the displacement sensor head 21 and the cords are arranged on the stator side, and a thin plate of SUS is formed on the surface of the stator to seal the gas generated from it. A structure in which only the electromagnet yoke and the sensor targets are arranged on the mover 17 side may be considered as a can structure by brazing.

FIGS. 6 and 7 are layouts of rails and electromagnets in a conventional magnetic levitation transfer apparatus in which electromagnets and sensors are arranged on the stator side. In particular, FIG. 6 shows a method of supporting the guide direction and the yawing direction. FIG. 7 is a plan view for explaining FIG. 7, and FIG. 7 is a cross-sectional view in a direction perpendicular to the traveling direction.

With reference to FIG. 7, the stators 36a and 36b are arranged so as to face each other with a constant space therebetween, and the stator 3
The mover 24 floats and runs between 6a and 36b. Guide electromagnets 27a and 27b are arranged vertically on one of the stators 36a so as to face the mover 24, and so as to face the guide electromagnets 27a and 27b.
The mover 24 is provided with an electromagnet yoke 28. The other stator 36b is provided with guide sensors 30a and 30b vertically so as to face the mover 24.
A guiding permanent magnet rail 31 is provided between 0a and 30b. The mover 24 includes guide sensors 30a and 3a.
0b so as to face 0b
a and 29b are provided, and the guiding sensor target 29a is provided.
And 29b, a permanent magnet 32 for attraction and a permanent magnet 33 for repulsion are provided. Repulsion permanent magnets 25a and 25b are provided on the lower surface of the upper portion of the mover 24, and the stator 36 is provided so as to face the repulsion permanent magnets 25a and 25b.
A permanent magnet 26a for levitation is provided on a, and a stator 36b
Is provided with a levitation permanent magnet 26b. Stator 36a
A motor coil 34 is provided below the motors 36 and 36b, and a motor field permanent magnet 35 is provided on the mover 24 so as to face the motor coil 34.

In the magnetic levitation transfer apparatus constructed as described above, one of the side surfaces of the mover 24 is attracted by the guide permanent magnet rail 31 and the attraction permanent magnet 32 to support in the guide direction, and the side surface of the mover 24 is attracted. The other is the guiding electromagnet 2
This is done by controlling the magnetic attraction force of 7. The yawing direction is passively supported by the repulsive force acting between the repulsion permanent magnet 33 and the guide permanent magnet rail 31 arranged at the front and rear ends of the moving element 24 in the traveling direction. Further, support in the levitation direction and the pitching direction is performed by the repulsive force between the levitation permanent magnet rail 26 and the repulsion permanent magnet 25. The support in the rolling direction is performed by controlling the magnetic attraction force of the guide electromagnets 27a and 27b arranged above and below the side surface. Since the above-mentioned magnetic levitation transport device employs passive support by permanent magnets, the number of active control axes by electromagnets can be reduced, and the operation of switching the electromagnets to be driven depending on the position in the traveling direction of the mover 24. Can be simplified.

[0011]

However, in the magnetic levitation transfer apparatus shown in FIGS. 6 and 7 described above,
Since the electromagnet yoke 28 and the sensor target 29 are close to each other, the magnetic flux from the guiding electromagnet 27 reaches the sensor target 29 and interferes with the sensor output. Further, the passive rigidity due to the attraction permanent magnet 32 is weak, so that stable levitation cannot be performed.

Therefore, a main object of the present invention is to provide a magnetic levitation transfer device which can increase passive rigidity and can float stably.

[0013]

SUMMARY OF THE INVENTION The present invention is a magnetic levitation transfer apparatus including a stator composed of an upper stage and a lower stage, and a mover traveling so as to straddle the upper stage of the stator. The coil for the linear motor is provided in the upper part, and a plurality of levitation sensor heads are provided on both sides of the coil for the linear motor along the traveling direction, and a plurality of levitation sensor heads are switched in the lower part of the upper stage of the stator. A switching sensor head for detecting timing and a linear motor positioning sensor head are provided, and rails are provided on both sides of the switching sensor head and the linear motor positioning sensor head so as to extend along the traveling direction. An electromagnet for levitation control is provided above the lower stage of the stator.

A linear motor field permanent magnet is provided above the mover so as to face the linear motor coil, and a sensor target is provided so as to face the levitation sensor target. Is provided with a levitation permanent magnet so as to face the rail. The mover is levitated by the magnetic force of the levitation permanent magnet, and the levitation control electromagnet is controlled according to the detection output of the levitation sensor head to keep the gap between the mover and the stator constant, The surface of the stator on which the sensor heads are arranged is brazed with a stainless steel thin plate to form a can structure.

[0015]

In the magnetic levitation transfer apparatus according to the present invention, the gap between the movable element and the movable element is detected by the levitation sensor provided above the upper portion of the stator, and the lower portion of the stator is adjusted so that the gap becomes constant. The levitation control electromagnet provided in the upper portion is controlled, and a plurality of levitation sensor heads are sequentially switched at the switching timing detected by the switching sensor head. The mover moves while floating above the stator by the driving force of the linear motor coil on the stator side and the permanent magnet for the linear motor field on the mover side.

[0016]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, showing a left view I and a right view II which are displaced from the center in the traveling direction.

In FIG. 1, the magnetic levitation transport device is composed of a mover 1, an upper stage 2a of a stator, a middle stage 2b, and a lower stage 2c. The mover 1 has a base material made of SUS304 or SUS316L, a yoke 3 and a linear motor field permanent magnet 4 are provided in the center of the upper part thereof, and a sensor target 5 is provided on the left side of them. There is. A levitation control switching sensor target 14 is provided on the lower left side of the mover 1, and a linear motor positioning sensor target 13 and a levitation permanent magnet 1 are provided on the lower right side.
2 and are provided. A levitation control electromagnet yoke 15 is provided on the lower left side of the mover 1.

On the other hand, the upper stage 2a, the middle stage 2b, and the lower stage 2c of the stator are the same as those of the mover 1 in the same manner as SUS304 or S.
It is composed of US316. A yoke 8 and a linear motor coil 7 wound around the yoke 8 are provided on the upper portion of the upper stage 2a of the stator so as to face the permanent magnet 4 for linear motor field of the mover 1, and on the left side thereof. The levitation sensor head 6 faces the sensor target 5 of the mover 1.
Is provided. A levitation permanent magnet yoke 11 serving as a rail is provided on the lower left side of the upper stage 2a of the stator, and a levitation control switching sensor head 10 is provided on the right side thereof so as to face the levitation control switching sensor target 14 of the mover 1. .

On the lower right side of the upper stage 2a of the stator, the mover 1 is provided.
A levitation permanent magnet yoke 11 is provided so as to face the levitation permanent magnet 12, and a linear motor positioning sensor head 9 is provided on the left side thereof.

A linear motor, coils for sensors,
In order to seal the gas generated from the molding material, a thin plate such as SUS304 is brazed on each surface to form a scan structure.

A levitation control electromagnet 16 is provided above the lower stage 2c of the stator so as to face the levitation control electromagnet yoke 15. The lower stage 2c of the stator is also the upper stage 2a of the stator
Similarly to the can structure.

FIG. 2 shows the levitation sensor head 6 shown in FIG.
FIG. 3 is a diagram showing the arrangement of the sensor target 5 in the traveling direction.

The levitation sensor consisting of the sensor target 5 and the levitation sensor target 6 shown in FIG. 1 must detect the levitation position of the mover 1 through the SUS plate of each wall, so that the number of carriers is about 10 kHz. A reluctance sensor is used. A total of four sensor targets 5a, 5a, 5b, 5b are arranged on the front, rear, left and right of the mover 1. The sensor head 6 is a long one, and a plurality of sensor heads 6a, 6b, 6c ... Are arranged continuously on the left and right along the traveling direction.
The distance between the front sensor targets 5a and 5b is such that at least one sensor head 6 is inserted between them. As a material for the sensor head core and the sensor target, a ferrite material having a large specific resistance and an excellent high-frequency permeability is used in order to reduce the influence of the eddy current.

FIG. 3 is a view showing the arrangement of the levitation permanent magnet, the levitation control electromagnet yoke, the levitation control electromagnet, and the levitation permanent magnet yoke in the traveling direction. With reference to FIG. 3, the levitation permanent magnets 12a and 12b and the levitation control electromagnet yoke 1
5a and 15b are arranged side by side in front of and behind each other, and are arranged at four positions on the front, rear, left and right of the mover 1. The levitation permanent magnet yoke 11 is continuously installed in the traveling direction without interruption. As for the levitation control electromagnet 16, a plurality of elongated ones 16a, 16b, 16c are arranged in succession on the left and right, and at least one levitation control electromagnet 16 is provided between the levitation control electromagnet yokes 15. I am asked to enter. The position of the levitation sensor target 5 and the levitation control electromagnet yoke 15 on the mover 1 in the traveling direction is the same, and the levitation sensor head 6 and the levitation control electromagnet 16 have the same length. These are dimensions and have the same phase relationship with respect to the traveling direction, that is, the edges are aligned.

Next, the control system of the magnetic levitation carrier according to the present invention will be described. First, the upper stage 2a of the stator
A plurality of levitation control switching sensor heads 10 arranged along the traveling direction detect the levitation control switching sensor target 14 attached to the mover 1, and the position of the mover 1 is detected. This sensor is a miniature pot type reluctance sensor.

Next, according to the position of the mover 1, only a necessary signal is selected from a plurality of levitation sensor signals by a multiplexer (not shown). These signals are given to a central control circuit and are arithmetically processed to create control signals. The demultiplexer gives a signal only to the amplifier section of some electromagnets to be driven among the plurality of electromagnets. The mover 1 is attracted in the upward direction by the levitation permanent magnet 12, while the control electromagnet 16 exerts a downward attraction force. Therefore, by controlling the attraction force of the electromagnet, the levitation direction is increased. , Pitching direction and rolling direction can be controlled.
The guide direction and the yawing direction are passively controlled by the staggering force of the levitation permanent magnet 12, the levitation permanent magnet yoke 11, the levitation control electromagnet 16, and the levitation control electromagnet yoke 15. That is, it is basically an active three-axis control system.

A coreless DC brushless linear motor is applied because driving and positioning of the mover 1 in the traveling direction can be easily unitized and disturbance to the magnetic levitation control system can be reduced. A linear motor field permanent magnet 4 and a yoke 3 are arranged on the mover 1, and an air-core coil 7 and a yoke 8 are arranged on the stator 2. In the case of a brushless motor, a Hall IC or the like is usually attached to each coil as a position detecting element for energization timing, but since heat resistance during baking is a problem and a large number of them are required, it is used in this embodiment. Has not been done.

Further, in this embodiment, the number of sensors that can measure the absolute position in the traveling direction is limited because the movable element 1 has no active parts. Furthermore, there is currently no one that can be used in a high temperature and vacuum environment. Therefore, depending on how the drive and positioning control is performed, in normal drive, a chart of energization timing is input to the computer, and after returning to the home position, each motor coil is energized according to the chart, and the carrier wave is generated. Form and drive. For positioning, a positioning sensor head is embedded in a preset position, and when the mover 1 reaches a certain position, normal driving is switched to positioning control, and positioning control is performed using PWM control or the like.

FIG. 4 is a diagram showing an example of the positioning sensor. As a positioning sensor, linear resolver, inductosyn, etc. can be considered, but positioning accuracy is ± 0.5.
If the specification is about mm, a very simple structure as shown in FIG. 4 can be applied. With the magnetic levitation control system,
Since the floating direction, the pitching direction, and the rolling direction of the mover 1 are controlled, the positioning sensor target 1
The position can be detected only by adding an inclination in the traveling direction of 3.

[0030]

As described above, according to the present invention, the levitation control electromagnet is provided in the lower upper part of the stator, the levitation control electromagnet yoke is provided in the lower part of the mover, and the sensor target is provided above the mover. Since the magnetic flux of the levitation control electromagnet does not reach the sensor target, the interference of the sensor output does not occur. Furthermore, a levitation permanent magnet is provided on the mover side so as to face the rail provided in the lower part of the upper part of the stator, and the levitation control electromagnet provided in the lower part of the stator is controlled to levitate the mover. Therefore, the passive rigidity can be increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement in a traveling direction of a flying sensor head and a sensor target shown in FIG.

FIG. 3 is a diagram showing an arrangement of a levitation permanent magnet, a levitation control electromagnet yoke, a levitation control electromagnet, and a levitation permanent magnet yoke in the traveling direction.

FIG. 4 is a diagram showing an example of a positioning sensor.

FIG. 5 is a vertical sectional view of a conventional magnetic levitation transport device.

FIG. 6 is a layout diagram between a rail and an electromagnet in a conventional magnetic levitation transport device in which an electromagnet, a sensor, and the like are disposed on a stator side, and a plan view for explaining a supporting method in a guide direction and a yawing direction. .

FIG. 7 is a cross-sectional view of a conventional magnetic levitation transport device in a direction perpendicular to the traveling direction.

[Explanation of symbols]

 1 Mover 2a Stator upper stage 2b Stator middle stage 2c Stator lower stage 3 Yoke 4 Linear motor permanent magnet 5 Sensor target 6 Levitation sensor head 7 Linear motor coil 8 Yoke 9 Linear motor positioning sensor head 10 Levitation control Sensor head for switching 11 Permanent magnet yoke for levitation 12 Permanent magnet for levitation 13 Sensor target for linear motor positioning 14 Sensor target for levitation control switching 15 Magnification control electromagnet yoke 16 levitation control electromagnet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B61B 13/08 B H01F 7/20 E H02P 7/00 101 B 8625-5H B61B 13/08 B B65G 54/02

Claims (1)

[Claims] 1. A magnetic levitation transport apparatus including a stator composed of an upper stage and a lower stage, and a mover that travels so as to straddle the upper stage of the stator, wherein the upper stage of the upper stage of the stator comprises:
A linear motor coil is provided, a plurality of levitation sensor heads are provided on both sides of the linear motor coil along the traveling direction, and a plurality of levitation sensor heads are provided below the upper stage of the stator. A switching sensor head for detecting the switching timing and a linear motor positioning sensor head are provided, and extend on both sides of the switching sensor head and the linear motor positioning sensor head along the traveling direction. A rail is provided, a levitation control electromagnet is provided above the lower stage of the stator, and a linear motor field permanent magnet is provided above the mover so as to face the linear motor coil. together is, the sensor target so as to face is provided on said levitating sensor, the bottom of the mover, the Le Levitating permanent magnets are provided so as to face the levitating portion, and levitating control electromagnet yokes are provided so as to face the levitating control electromagnets, and the mover levitates due to the magnetic force of the levitating permanent magnets, Further, according to the detection output of the levitation sensor head, the levitation control electromagnet is controlled to make the gap between the mover and the stator constant, and the electromagnets and the sensor heads are arranged. A magnetic levitation transfer device characterized in that a thin stainless plate is brazed to the surface of the stator.