JP2002136046A - Magnetic bearing motor and excimer laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a non-magnetic metal material for partition wall and then to make it possible to reduce wobbling of a rotating body and vibration of a stator caused by the drive current given to a motor stator. SOLUTION: In a magnetic bearing motor wherein a motor 11 rotationally drives the rotating body 4 and a magnetic bearing 9 supporting the rotating body 4 floatingly are arranged, the internal circumference side of the motor stator 11a of the motor 11 is hermetically sealed with a first partition wall 45 and the internal circumference side of an induction displacement sensor 9a detecting the position of the rotating body of the magnetic bearing 9 is hermetically sealed with second partition wall 44, each independently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing motor having a hermetically sealed structure in which whirling of a rotating body and vibration of a stator are reduced, and an excimer laser device using the motor.

[0002]

2. Description of the Related Art Unlike a contact type plain bearing or a ball bearing, a magnetic bearing rotatably supports a rotor in a non-contact manner, so that there is little mechanical loss, there is no friction and wear, and no lubricating oil is required. It has advantages such as low vibration and noise, and maintenance-free. Examples of the use of a magnetic bearing having such characteristics include a turbo-molecular pump for creating a vacuum environment with a small amount of impurities, and a spindle for a machine tool capable of performing ultra-high-speed rotation.

[0003] When a magnetic bearing is used in an environment in which impurities are extremely disliked or in a corrosive environment, outgassing or corrosion from materials constituting the magnetic bearing (for example, electromagnetic steel sheets, copper wire coils, organic materials, etc.). Is a problem. For this reason, a coating material is provided on the surface of the magnetic bearing to protect the above constituent materials from a corrosive environment. An excimer laser device is an example using a magnetic bearing motor in which such a configuration, that is, a magnetic bearing having a sealed structure and a motor are arranged at positions adjacent to each other.

FIG. 5 shows a schematic structure of a conventional excimer laser device. As shown in FIG. 5, the conventional excimer laser device, a halogen-based gas _(F 2, C1 _2, etc.)
, A pre-ionization electrode (not shown) for pre-ionizing the laser gas disposed inside the laser container 101, and oscillation of the laser light disposed inside the laser container 101. It has a pair of main discharge electrodes 102, 102 for obtaining a discharge.
Further, a pair of main discharge electrodes 10
A circulation fan 103 for creating a high-speed laser gas flow between the two 102 is arranged. Note that laser light extraction windows 105, 105 are provided at both ends of the pair of main discharge electrodes 102, 102.

The circulation fan 103 has a rotating shaft 104 penetrating therethrough and protruding from both ends. The rotating shaft 104 is provided with two radial magnetic bearings 106 and 107 provided at both ends of the laser vessel 101. One axial magnetic bearing 108 rotatably floats and is supported in a non-contact manner. A motor 109 for driving the circulation fan 103 is provided on the shaft end side of the radial magnetic bearing 107.

On the rotating shaft 104, the electromagnetic target 10 of each of the magnetic bearings 106, 107, 108 made of a magnetic material is provided.
6d, 107d, 108e and sensor target 10
6c, 107c, 108d and the motor rotor 109b are fixed. The electromagnets 106b, 107b, 108b, and 108c, the induction displacement sensors 106a, 107a, and 108a, and the motor stator 109a are arranged at positions facing these. With the above configuration, the rotation axis 104 is the rotation axis 10 of the six degrees of freedom of the object.
Each of the magnetic bearings 106 and 10 has five degrees of freedom other than the four rotations.
By being supported at 7, 108, stable rotation can be obtained.

The electromagnets 106b, 107b of the radial magnetic bearings 106, 107 and the induction type displacement sensors 106a,
107a and thin cylindrical partitions 110, 111 made of a non-magnetic material, for example, austenitic stainless steel, are provided on the inner peripheral surface of the motor stator 109a, and both ends are welded to the housing for accommodating each stator component. To form a sealed structure. Similarly, the axial magnetic bearing 108 has the electromagnets 108b, 1b.
08c and 108d and the exposed surface of the inductive displacement sensor 108a are provided with thin disk-shaped partition walls 11 made of a non-magnetic metal material.
It is covered with 2,113. Further, the motor rotor 109
A partition 114 made of a nonmagnetic metal material is also provided on the outer peripheral surface of b.

[0008]

In the above-described conventional magnetic bearing motor, when a rotational driving current is excited in the motor stator 109a, an eddy current or electromagnetic noise is generated in the partition wall 111 by the AC magnetic flux of the motor. The current and the electromagnetic noise are easily transmitted through the inside of the partition wall 111 and affect the detection signal of the inductive displacement sensor 107a. That is,
The same noise as the exciting current frequency of the motor stator 109a is added to the detection signal of the inductive displacement sensor 107a,
There is a problem that the rotating shaft 104 is vibrated by the radial magnetic bearing 107.

Incidentally, in order to solve this problem, the partition walls are also made of a non-conductive material such as Teflon (registered trademark), ceramics, glass and the like. However,
When it is desired to extremely reduce the emission gas under a special corrosive environment as in an excimer laser device, a non-magnetic metal material is most excellent. In addition, since the nonmagnetic metal material generally has excellent mechanical strength as compared with the nonconductive material, the thickness of the partition wall can be reduced, and the manufacturing is easy and the cost is low.

The present invention has been made in view of the above circumstances, and uses a non-magnetic metal material as a partition wall, and can further reduce whirling of a rotating body and vibration of a stator due to a rotational driving current applied to a motor stator. It is an object of the present invention to provide a magnetic bearing motor and an excimer laser device using the motor.

[0011]

According to a first aspect of the present invention, there is provided a magnetic bearing motor in which a motor for rotating a rotating body and a magnetic bearing for floatingly supporting the rotating body are arranged. A magnetic bearing motor characterized in that the peripheral surface is individually hermetically sealed by a first partition and the inner peripheral surface of an inductive displacement sensor for detecting the position of a rotating body of the magnetic bearing is individually sealed by a second partition. is there. The motor that drives the rotating body and the magnetic bearing that supports the levitation can be arranged adjacent to each other in the magnetic bearing motor.

As described above, the first partition wall for hermetically sealing the inner peripheral surface of the motor stator and the second partition wall for hermetically sealing the inner peripheral surface of the inductive displacement sensor are formed separately from each other. By separating, the eddy current and the electromagnetic noise in the first partition generated by the AC magnetic flux of the motor when the rotation drive current is excited in the motor stator are hardly transmitted to the second partition,
The influence on the detection signal of the inductive displacement sensor can be reduced.

According to a second aspect of the present invention, there is provided a laser vessel for enclosing a laser gas, a pair of main discharge electrodes for obtaining a discharge arranged in the laser vessel and capable of oscillating laser light, and a rotating shaft. An excimer laser device comprising: a circulating fan for generating a high-speed laser gas flow between the pair of main discharge electrodes; and a magnetic bearing motor according to claim 1 for driving the rotating shaft to rotate.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIGS. 1 and 2 show an excimer laser device provided with a magnetic bearing motor according to a first embodiment of the present invention. FIG.
FIG. 2 is an enlarged view of a main part of FIG. 1.

The excimer laser apparatus includes a laser container 1 in which a laser gas containing a halogen-based gas, for example, a fluorine gas is sealed, a preionization electrode (not shown) for preionizing the laser gas disposed inside the laser container 1, It has a pair of main discharge electrodes 2 and 2 arranged inside the laser vessel 1 for obtaining a discharge capable of oscillating laser light.
Further, a circulating fan 3 for generating a high-speed laser gas flow between the pair of main discharge electrodes 2 and 2 is provided in the laser vessel 1.
Is arranged.

The laser beam is obtained by applying a high voltage between the pair of main discharge electrodes 2 and 2 to perform a laser excitation discharge. The generated laser light is taken out of the laser container 1 via windows 5 and 5 provided on the side wall of the laser container 1. When the above-described laser-excited discharge is performed, the laser gas between the pair of main discharge electrodes 2 and 2 deteriorates, and the deterioration deteriorates the discharge characteristics and makes it impossible to perform repetitive oscillation. For this reason, the circulation fan 3 circulates the laser gas in the laser vessel 1 and exchanges the laser gas between the pair of main discharge electrodes 2 for each discharge, thereby performing stable repetitive oscillation.

The circulation fan 3 has a rotating shaft 4 penetrating therethrough and protruding from both ends. The rotating shaft 4 is rotatably supported in a non-contact manner by a radial magnetic bearings 8 and 9 and an axial magnetic bearing 10 housed in a bearing housing 6 and a motor housing 7 provided at both ends of the laser container 1. Then, the motor 11 gives a rotating power to the rotating shaft 4 of the circulation fan 3.

Thread groove labyrinths 14 and 15 are provided on the laser housing 1 side of the bearing housing 6 and the motor housing 7 to prevent dust from entering the housing. Accordingly, it is possible to prevent dust generated in the laser container 1 from entering the bearing housing 6 and the motor housing 7 and from entering the rolling surfaces of the protective bearings 12 and 13. Further, the laser vessel 1 is provided with a gas outlet 16, and the laser gas flowing out from the gas outlet 16 is subjected to dust removal by dust removal filters 18, 18 in the gas introduction chambers 17, 17, and the gas introduction pipe is provided. 1
9 and 19 are introduced to the shaft ends of the bearing housing 6 and the motor housing 7. That is, by circulating the gas as indicated by the arrow in the figure, dust can be reliably prevented from entering the housings 6 and 7.

FIG. 2 is an enlarged view of a main part showing the periphery of the motor housing 7 in an enlarged manner. The motor housing 7 includes a bearing housing body 7a, a motor housing body 7b, and a bearing cover 7c. The bearing housing body 7a is attached to a side wall of the laser container 1. The motor housing main body 7b and the bearing cover 7c are sequentially attached to the bearing housing main body 7a. Each of the mounting surfaces is provided with a sealing groove 52, 54, 56, and the sealing material 52 is provided in each of the sealing grooves 52, 54, 56.
3, 55, 57 are attached to hermetically seal the laser gas.
Note that it is preferable to use a metal (e.g., stainless steel or aluminum) sealing material that emits little gas such as moisture contaminating the laser gas as the sealing material.

The inductive displacement sensor 9a and the electromagnet 9b of the radial magnetic bearing 9 are accommodated in the bearing housing body 7a in a state where the relative positions are determined by the spacer 41 and the side plate 42. Then, the inductive displacement sensor 9a and the electromagnet 9
A thin-walled cylindrical partition wall 44 is disposed on the inner peripheral surface of the bearing housing body b.
2 is fixed by welding or the like. By providing the partition wall 44 in this manner, the inductive displacement sensor 9a and the electromagnet 9b, which have poor corrosion resistance to the laser gas, do not come into contact with the laser gas. The partition wall 44 has corrosion resistance to the laser gas and is made of a non-magnetic material, for example, austenitic stainless steel.

The motor housing body 7b includes a motor 1
One motor stator 11a and the side plate 43 are housed. A thin-walled cylindrical partition wall 45 is disposed on the inner peripheral surface of the motor stator 11a, and both ends of the partition wall 45 are fixed to the motor housing body 7b and the side plate 43 by welding or the like. This prevents the motor stator 11a from coming into contact with the laser gas.

As described above, the partition wall 45 for hermetically sealing the inner peripheral surface of the motor stator 11 a of the motor 11 and the partition wall 44 for hermetically sealing the inner peripheral surface of the induction type displacement sensor 9 a of the radial magnetic bearing 9. By separating them from each other and separating them from each other, the eddy current and electromagnetic noise in the partition wall 45 generated by the AC magnetic flux of the motor when the rotation driving current is excited in the motor stator 11a are hardly transmitted to the partition wall 44, and the induction is prevented. The influence on the detection signal of the mold displacement sensor 9a is reduced, whereby the displacement output signal with less noise can be extracted from the inductive displacement sensor 9a.

On the other hand, the displacement sensor target 9e of the radial magnetic bearing 9, the electromagnet target 9f, and the motor rotor 11b of the motor 11 are fixed to the rotating shaft 4 of the circulation fan 3 in a state where the relative positions are determined by the rotor spacers 46 and 47. Are arranged in an airtight space communicating with the inside of the laser container 1. Here, as a magnetic material constituting the displacement sensor target 9e and the electromagnet target 9f, permalloy (Fe-Ni alloy containing 30 to 80% Ni) having good corrosion resistance to fluorine gas contained in the laser gas is used. are doing.

In the displacement sensor target 9e and the electromagnet target 9f, an eddy current loss occurs due to a magnetic field change caused by rotation. In order to reduce the eddy current loss, a structure in which thin plates are laminated is adopted as the displacement sensor target 9e and the electromagnet target 9f. In the case where a problem such as gas pooling between the laminated thin plates and contamination of the laser gas occurs, the displacement sensor target 9e and the electromagnet target 9f may be formed of an integral material.

The motor rotor 11b of the motor 11
Is composed of a laminated silicon steel sheet and aluminum composite material. When the motor rotor 11b is made of a composite material of silicon steel plate and aluminum, it is difficult to uniformly apply Ni plating suitable for corrosion resistance to the surface with good adhesion. Therefore, a partition wall 48 is arranged on the outer peripheral surface of the motor rotor 11b, and both ends of the partition wall 48 are fixed to the side plates 49, 50 by welding or the like, and the side plates 49, 50 and the rotating shaft 4 of the circulation fan 3 are fixed by welding or the like. To form an air-tight space, and the motor rotor 11b
Eliminates contact with the laser gas. This partition 4
8 is made of austenitic stainless steel for the reason described above.

As the protective bearing 12, the rolling elements 12a are made of alumina ceramics, zirconia ceramics or the like, and the outer ring 12b and the inner ring 12c are made of SUS440C.
And other rolling bearings made of stainless steel.

FIGS. 3 and 4 show an excimer laser device provided with a magnetic bearing motor according to a second embodiment of the present invention. FIG. 3 is an enlarged sectional view (corresponding to FIG. 2) of a main part. FIG. 4 is a sectional view taken along line AA of FIG.

The difference between this embodiment and the first embodiment is that the radial magnetic bearing 9 is such that the protruding portion of the core of the electromagnet 9b penetrates the partition wall 44 and the inner peripheral surface thereof is exposed. Is a point. Here, since the iron core of the electromagnet 9b is in contact with the laser gas, it needs to have corrosion resistance. For this reason, permalloy having good corrosion resistance to laser gas is used. By fixing the iron core of the electromagnet 9b to the partition wall 44 by welding or the like, it is possible to prevent the coil winding of the electromagnet 9b having poor corrosion resistance against the laser gas from coming into contact with the laser gas.

According to this embodiment, the magnetic gap between the iron core of the electromagnet 9b and the electromagnet target 9f is prevented from being enlarged by the partition 44, the efficiency as a magnetic bearing is improved, the power consumption is reduced and the size is reduced. Can be achieved.

[0030]

As described above, according to the present invention,
A first partition for hermetically sealing the inner peripheral surface of the motor stator;
By forming a second partition for hermetically sealing the inner peripheral surface of the inductive displacement sensor and separate from each other, a second partition generated by an AC magnetic flux of the motor when a rotational driving current is excited in the motor stator. The eddy current and electromagnetic noise in the first partition are less likely to be transmitted to the second partition, and the influence on the detection signal of the inductive displacement sensor can be reduced. This prevents the magnetic bearing from vibrating the rotating body at the same frequency as the rotational driving current of the motor, thereby reducing the whirling of the rotating body and having a sealed structure capable of reducing the vibration of the stator. A bearing motor can be provided.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of an excimer laser device including a magnetic bearing motor according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged sectional view (corresponding to FIG. 2) of a main part of an excimer laser device provided with a magnetic bearing motor according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is an overall sectional view of an excimer laser device provided with a conventional magnetic bearing motor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser container 2 main discharge electrode 3 circulation fan 4 rotating shaft 7 motor housing 8, 9 radial magnetic bearing 9 a inductive displacement sensor 9 b electromagnet 9 e displacement sensor target 9 f electromagnet target 10 axial magnetic bearing 11 motor 11 a motor stator 11 b motor rotor 16 gas flow Outlet 12, 13 Protective bearing 14, 15 Groove labyrinth 17 Gas introduction chamber 18 Dust removal filter 19 Gas introduction pipe 44, 45, 48 Partition wall

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01S 3/225 H01S 3/03 Z 5H607 H02K 3/44 J 5/128 3/223 E (72) Inventor Hiroyuki Shinozaki 11-1 Haneda-Asamachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Atsushi Oyama 4-1-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Ebara Densan Co., Ltd. (72) Inventor Ibarada Toshimitsu 4-1-1, Motofujisawa, Fujisawa-shi, Kanagawa F-term in Ebara Densan Co., Ltd. (Reference) 3H031 AA03 BA22 3J102 AA01 BA03 BA19 CA02 CA05 CA14 DA02 DA03 DA09 DB05 GA13 5F071 AA06 DD03 DD08 EE04 JJ05 5H604 BB09 BB14 CC01 CC02 CC05 CC11 PE07 5H605 AA17 BB05 BB10 BB17 DD37 EA06 EB03 EB06 EB33 5H607 AA04 BB01 BB06 BB14 CC01 CC03 CC09 DD01 DD02 DD16 GG01 GG02 GG09 GG21

Claims (2)

[Claims] 1. A magnetic bearing motor in which a motor that rotationally drives a rotating body and a magnetic bearing that levitates and supports the rotating body are arranged, wherein an inner peripheral surface of a motor stator of the motor is a first partition wall.
A magnetic bearing motor, wherein an inner peripheral surface of an inductive displacement sensor for detecting a position of a rotating body of the magnetic bearing is individually hermetically sealed by a second partition. 2. A laser container for enclosing a laser gas, a pair of main discharge electrodes arranged in the laser container for obtaining a discharge capable of oscillating laser light, and a pair of main discharge electrodes having a rotation axis. An excimer laser device comprising: a circulating fan for generating a high-speed laser gas flow between electrodes; and the magnetic bearing motor according to claim 1 for driving the rotating shaft to rotate.