JPH0750734B2 - Magnetic levitation elevator - 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 elevator for raising and lowering a carrier in an atmosphere such as a vacuum without contact.

[0002]

2. Description of the Related Art An example of such an elevator will be described with reference to FIG. In the figure, for example, a transfer chamber 30 in a vacuum atmosphere
1, a carrier table 31 on which a semiconductor wafer W is placed is provided so as to be vertically movable via a linear bearing 32, and is vertically moved by, for example, an air actuator 33. A bellows 34 is interposed between the peripheral portion of the carrier 31 and the bottom of the carrier chamber to seal the vacuum atmosphere from the outside.

[0003]

However, in the above apparatus, the bellows 34 expands and contracts as the carrier 31 moves up and down. Therefore, the life of the bellows 34 becomes shorter than that of the other mechanisms, and fine powder of the bellows is generated due to expansion and contraction, which pollutes the vacuum atmosphere around the carrier 31.

An object of the present invention is to provide a long-life magnetic levitation elevator that does not pollute the atmosphere such as vacuum.

[0005]

For this reason, according to the present invention, a floating clearance detection sensor, a radial magnetic bearing, and a vertically movable body are arranged in this order from the top on the outer periphery of a bottomed non-magnetic cylindrical body communicating with the transfer chamber. A laminated magnetic bearing, a radial magnetic bearing, and a floating gap detection sensor, respectively, and vertical drive means for the laminated magnetic bearing. A cylindrical body is formed in the cylindrical body by forming a gap with the inner peripheral surface thereof. Provided is a magnetic levitation elevator in which a magnetic pole facing the levitation gap detection sensor, the radial magnetic bearing, and the laminated magnetic bearing is provided on the cylindrical body, and a carrier is provided at the top of the cylindrical body inside the carrier chamber. To be done.

Further, according to the present invention, a floating clearance detection sensor, a radial magnetic bearing, a laminated magnetic bearing, and a radial, which can move up and down in order from the top, are provided on the outer periphery of a bottomed non-magnetic cylindrical body communicating with the transfer chamber. A magnetic bearing and a levitation gap detection sensor are respectively provided, and a unit is constituted by the gap detection sensor, the radial magnetic bearing and the laminated magnetic bearing, and vertical drive means for moving the unit up and down is provided. A cylindrical body is provided by forming a gap with the inner peripheral surface thereof, and magnetic poles facing the levitation gap detection sensor, the radial magnetic bearing and the laminated magnetic bearing are respectively provided on the cylindrical body, and the transfer chamber is provided at the top of the cylindrical body. There is provided a magnetic levitation elevator which is provided with a carrier table.

The inside of the transfer chamber has an atmosphere such as vacuum.

Further, according to the present invention, there is provided a rotating means for arbitrarily rotating the cylindrical body around the axis of the cylindrical body.

The vertical drive means is preferably composed of a ball nut, a ball screw and a drive motor for the ball screw, which are connected to the laminated magnetic bearing via an arm.

[0010]

In the magnetic levitation elevator constructed as described above, when the drive motor is rotated forward and backward to move the laminated magnetic bearing up and down, the columnar body moves up and down through the magnetic poles facing the bearing to move up and down the carrier. Let At this time, since the columnar body moves up and down in a cylindrical body sealed from the outside by magnetic levitation without contact, the atmosphere such as vacuum is not contaminated by the external environment.

Further, unlike the bellows of the conventional apparatus, since there is no member that deforms, the life is extended.

[0012]

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

In FIG. 1, a cylinder 2 made of a thin non-magnetic material is fixedly installed in a through hole 1a at the bottom of the transfer chamber 1 kept in an atmosphere such as a vacuum, and the cylinder 2 is erected on a base 3. The internal space is maintained in an atmosphere such as a vacuum.

A transfer table 4 is provided in the transfer chamber 1, and a column 5 is vertically provided on the lower surface of the transfer table 4, and the column 5 hangs down with an annular gap C provided in the cylinder 2. Has been done.

On the outer circumference of the cylinder 2, a first sensor 6 for detecting a floating clearance and a first radial magnetic bearing are arranged in this order from above.
Floating bearing 7, laminated magnetic bearing lifting bearing 8, second floating bearing 9 similar to first floating bearing 7, and first sensor 6
A second sensor 10 similar to the above is provided. The sensors 6 and 7 are connected to a control unit (not shown), which controls the electromagnetic coils 7a of the magnetic bearings 7 and 9 so as to keep the annular clearance C constant at all times based on the signals from the sensors 6 and 7. A control current is supplied to 9a. A ball nut 12 is provided on the elevating bearing 8 via an arm 11, and a ball screw 13 screwed onto the ball nut 12 is rotated forward and backward by a drive motor (not shown). . Then, the ball nut 12, the ball screw 13, and the drive motor constitute a vertical movement means for the lifting bearing 8.

On the other hand, the column 5 is located at a position facing the lifting bearing 8 when the illustrated carriage 4 is in the lower original position.
Elevating magnetic poles 16 are provided. Therefore, the cylinder 5
Is moved up by a stroke S by the upward movement of the lifting bearing 8. Then, when the cylinder 5 rises from the original position by the stroke S, the first cylinder 6 faces the first sensor 6, the first levitation bearing 7, the second levitation bearing 9, and the second sensor 10, respectively. Sensor magnetic pole 14, first
A bearing magnetic pole 15, a second bearing magnetic pole 17, and a second sensor magnetic pole 18 are provided.

In FIG. 2, the first magnetic bearing for levitation 7 will be described as an example. The eight yokes 7A of the bearing 7 are respectively wound with electromagnetic coils 7a in the directions of arrows a and b, respectively. The magnetic flux F indicated by the arrow is generated between the magnetic pole 15 and the four protrusions of the magnetic pole 15, and the column 5 is magnetically levitated via the magnetic pole 15.

FIG. 3 shows an example of means for rotating the cylinder 5. By rotating the outer permanent magnet 22 with a member (not shown) as shown by an arrow R, the column 5 is rotated via the magnet 24. When the permanent magnet 22 is stopped at a predetermined position by a member (not shown), the magnet 24 and the column 5 are also stopped at that position, and the positioning is completed. As for the rotation and the positioning, not only the structure shown in FIG. 3 but also a well-known structure can be adopted, but the details of the illustration and the operation are omitted.

Next, the operation will be described.

When the magnetic bearings 7 and 9 are excited, the cylinder 5 is levitated via the magnetic poles 15 and 17, and an annular gap C is formed between the cylinder 5 and the cylinder 2.

Therefore, when the drive motor is normally rotated and the ball screw 13 is rotated counterclockwise when viewed from below, the lifting magnetic bearing 8 is moved upward via the ball nut 12.
Therefore, the column 5 moves upward via the lifting magnetic poles 16,
The semiconductor wafer W (FIG. 5) placed on the carrier 4 is raised. Contrary to the above, if the drive motor is reversely rotated to rotate the ball screw 12 in the clockwise direction in the opposite direction to the above, the carrier table 5
Is dropped.

FIG. 4 shows another embodiment of the present invention. According to the embodiment of FIG. 4, the first sensor 6 for detecting the levitation gap, the first levitation bearing 7 of the radial magnetic bearing, the lifting bearing 8 of the laminated magnetic bearing, the second levitation bearing 9, and the second sensor. 10 is housed in a housing 40 to provide a single unit 5
Configures 0.

In this embodiment, the arm 11 is connected to the housing 40, and the ball nut 12, the ball screw 13 and the drive motor constitute a vertical movement means for the unit 40.

Since the other points are the same as those of the embodiment shown in FIGS. 1 to 3, detailed description thereof will be omitted.

[0025]

Since the present invention is constructed as described above, it is possible to prevent contamination by the external environment such as vacuum atmosphere.

Further, it is possible to extend the life by eliminating the deformable member. Furthermore, since the radial magnetic bearing that is the levitation magnetic bearing and the laminated magnetic bearing that is the lifting magnetic bearing are separately provided, it is possible to control the radial magnetic bearing and the laminated magnetic bearing separately. The carrier table in the carrier chamber can be raised and lowered more accurately.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a magnetic bearing for levitation and a magnetic pole, which is orthogonal to the transport direction.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a side sectional view showing another embodiment of the present invention.

FIG. 5 is a side sectional view showing a conventional elevator.

[Explanation of symbols]

 C ... Annular gap 1 ... Transport chamber 2 ... Cylindrical 4 ... Transport platform 5 ... Column 6 ... First sensor 7 ... First floating bearing 8 ... For lifting Bearing 9 ... Second levitation bearing 10 ... Second sensor 12 ... Ball nut 13 ... Ball screw

Claims (3)

[Claims] 1. A levitation gap detection sensor, a radial magnetic bearing, a vertically movable laminated magnetic bearing, a radial magnetic bearing and a levitation gap are arranged on the outer circumference of a bottomed non-magnetic cylindrical body communicating with a transfer chamber. Each detection sensor is provided, and
A vertical drive means for the laminated magnetic bearing is provided, and a cylindrical body is provided in the cylindrical body with a gap formed between the cylindrical body and the inner peripheral surface thereof, and the floating gap detection sensor, the radial magnetic bearing and the laminated magnetic bearing are provided in the cylindrical body. A magnetic levitation elevator, characterized in that magnetic poles facing each other are provided, and a carriage is provided at the top of the columnar body so as to be positioned in the carriage chamber. 2. A floating clearance detection sensor, a radial magnetic bearing, a laminated magnetic bearing, a radial magnetic bearing, and a floating clearance, which can move up and down in order from above, on the outer circumference of a bottomed non-magnetic cylindrical body communicating with the transfer chamber. A detection sensor is provided respectively, and a unit is constituted by the gap detection sensor, the radial magnetic bearing and the laminated magnetic bearing, and vertical drive means for moving the unit up and down is provided. A columnar body is formed with a gap formed therein, and magnetic poles facing the levitation gap detection sensor, the radial magnetic bearing, and the laminated magnetic bearing are respectively provided on the columnar body, and the magnetic poles are positioned at the top of the columnar body to be transported in the transport chamber. A magnetic levitation elevator characterized by having a stand. 3. The magnetic levitation elevator according to claim 1, further comprising rotating means for arbitrarily rotating the cylindrical body around the axis of the cylindrical body.