JP2003134733A - Electromagnetic bearing motor and excimer laser apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic bearing motor and an excimer laser apparatus using the motor which can eliminate an axial electromagnetic bearing, have inexpensive and simple structure and enhance rigidity in the shaft direction. SOLUTION: In the electromagnetic bearing motor provided with a motor 50 for rotatably driving a rotational element 10 and a plurality of active radial electromagnetic bearings 30, 40 for rotatably supporting the rotational element 10, an electromagnet target 30e of the radial electromagnetic bearing 30 is disposed and shifted relative to an electromagnet 30b in the shaft direction, shaft force F1 is generated, an electromagnet target 40e of the other radial electromagnetic bearing 40 is disposed and shifted relative to an electromagnet 40b in the direction opposite to that of the shifted electromagnet target 30e of the radial bearing 30, and shaft force F2 opposite to the shaft force F1 is generated.

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, and more particularly to a magnetic bearing motor in which a rotor is rotatably supported by a magnetic bearing and an excimer laser device using the motor.

[0002]

2. Description of the Related Art FIG. 9 is a schematic view showing the structure of a conventional magnetic bearing motor. The magnetic bearing motor includes a rotating body 510 such as a rotor (impeller) and a flywheel, and a rotating shaft 520 protruding from both sides of the rotating body 510. Radial magnetic bearings 53 are provided on both sides of the rotating body 510.
0, 540 are provided, and the radial position of the rotary shaft 520 is controlled by these radial magnetic bearings 530, 540. Further, a motor 550 that rotationally drives the rotating body 510 is provided at the end of the rotating shaft 520 on the radial magnetic bearing 530 side. Further, an axial magnetic bearing 560 is provided at the end of the rotary shaft 520 on the radial magnetic bearing 540 side.
The position of the rotary shaft 520 in the axial direction is controlled by 0.

With such a configuration, the rotary body 510 is
The radial magnetic bearings 530 and 540 and the axial magnetic bearing 560 are rotatably supported. That is, the rotary shaft 520 has five degrees of freedom out of the six degrees of freedom of the object.
It is supported by 0, 540 and 560 and has one degree of freedom rotated by a motor 550. As described above, since the magnetic bearing motor is supported by the magnetic bearing of five-axis control, the structure becomes complicated as compared with a contact type bearing such as a normal ball bearing. Further, since each of the five degrees of freedom is controlled, the control circuit becomes complicated and the initial cost of the system becomes very high.

When such a magnetic bearing is used in an environment in which impurities are extremely disliked or in a corrosive environment, gas is released from the material forming the magnetic bearing (for example, electromagnetic steel plate, copper wire coil, organic material, etc.). The problem is corrosion. Therefore, it is necessary to provide a coating material on the surface of the magnetic bearing to protect the above constituent materials from the corrosive environment. An excimer laser device is an example of a device having such a configuration.

FIG. 10 is a schematic view showing the structure of an excimer laser device incorporating a conventional magnetic bearing motor. As shown in FIG. 10, halogen gas _(F 2, C1 _2, etc.)
In the inside of the laser container 600 in which the laser gas containing is contained, a preionization electrode (not shown) for preionizing the laser gas, and a pair of main discharge electrodes 610, 610 for obtaining an electric discharge capable of oscillating laser light. And are placed.

Further, the magnetic bearing motor is arranged inside the laser vessel, and the rotating body 510 includes a pair of main discharge electrodes 6.
Used as a cross-flow fan to create a high speed laser gas flow between 10,610. A pair of main discharge electrodes 6
Laser beam extraction windows 620 and 620 are provided on the side walls of the laser container 600 at both ends of the laser beams 10 and 610.

Since the gas used in the excimer laser device is corrosive, the magnetic bearings 530, 5
40 and 560 and the motor 550, the rotary shaft 52
0 and the stator are provided with partition walls 631 to 636 each made of a non-magnetic material to arrange the elements on the side of the rotating body 510 inside the laser container 600, and the elements on the stator side from the atmosphere inside the laser container 600. Isolated.
As described above, in the excimer laser device using the magnetic bearing motor, the structure of the device becomes more complicated.

Further, since such an excimer laser device is generally operated with the laser container 600 installed horizontally, almost no axial component force is generated by the weight of the rotating body 510. Further, although the cross-flow fan is used as described above, the cross-flow fan does not have an axial fluid force in view of the operating principle, and thus no external force is generated in the axial direction. Therefore, the axial rigidity of the excimer laser device may be extremely small, and the axial rigidity obtained by the slight magnetic shearing force generated in the radial magnetic bearings 530 and 540 is often sufficient. In this case, the axial magnetic bearing 560 can be eliminated and the structure can be simplified.

However, due to the mounting error at the time of installation and the deviation of the floating position in the radial magnetic bearings 530, 540, the axial component force due to the weight of the rotating body 510 becomes large, and the radial magnetic bearings 530, 5 described above are increased.
The axial rigidity obtained by the magnetic shearing force of 40 alone is insufficient. Further, as compared with the case where the axial magnetic bearing 560 is provided, the natural frequency of the system determined by the mass of the rotating body 510 and the rigidity in the axial direction becomes lower, so that the vibration easily occurs due to the low-frequency excitation. Further, since the damping force in the axial direction is insufficient, a great amount of vibration is generated in the axial direction. This allows
Stable rotation of the rotating body 510 is impaired, and stable operation cannot be performed.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has an inexpensive and simple structure without an axial magnetic bearing.
An object of the present invention is to provide a magnetic bearing motor capable of increasing axial rigidity and an excimer laser device using the motor.

[0011]

In order to solve the problems in the prior art, the first aspect of the present invention is
In a magnetic bearing motor including a motor that rotationally drives a rotating body and a plurality of active radial magnetic bearings that rotatably support the rotating body, the active radial magnetic bearing is
An electromagnet provided on the fixed side and an electromagnet target made of a magnetic material attached to the rotary shaft of the rotating body are provided, and the electromagnet target of at least one active radial magnetic bearing is axially arranged with respect to the electromagnet. Staggered to generate a first axial force, and the electromagnet target of the other active radial magnetic bearing with respect to the electromagnet,
It is characterized in that the electromagnet target of the at least one active radial bearing is arranged so as to be displaced in a direction opposite to a direction in which the electromagnet target is displaced so as to generate an axial force in a direction opposite to the first axial force.

As described above, by preliminarily shifting the electromagnet target of the active radial magnetic bearing with respect to the electromagnet in the axial direction, a large magnetic shearing force is generated in the axial direction to obtain the axial force in one direction. You can Therefore, by staggering the electromagnet target and the electromagnet so as to generate axial forces in mutually opposite directions by the two radial magnetic bearings, it is possible to increase axial rigidity. This makes it possible to obtain a sufficient axial rigidity while eliminating the axial magnetic bearing and making the structure inexpensive and simple.

A second aspect of the present invention is a magnetic bearing motor comprising a motor for rotationally driving a rotating body and a plurality of active radial magnetic bearings for rotatably supporting the rotating body, wherein the active radial magnetic The bearing includes an electromagnet provided on the fixed side and an electromagnet target attached to the rotating shaft of the rotating body, and the electromagnet targets of two or more active radial magnetic bearings are axially arranged with respect to the electromagnet. It is characterized in that it is provided with an actuator that is arranged along the same direction to generate a first axial force and to generate an axial force in a direction opposite to the first axial force.

As described above, in two or more radial magnetic bearings, by preliminarily shifting the electromagnet target in the same direction along the axial direction with respect to the electromagnet, a large magnetic shearing force (axial force) is generated in the axial direction. It is possible to generate a larger axial force as compared with the first aspect described above.
Therefore, by providing an actuator that produces an axial force in the direction opposite to this axial force, it is possible to further increase the axial rigidity, eliminate the axial magnetic bearing, and make the structure inexpensive and simple. It is possible to obtain directional rigidity.

A third aspect of the present invention is a magnetic bearing motor comprising a motor for rotationally driving a rotating body and a plurality of active radial magnetic bearings for rotatably supporting the rotating body, wherein the motor is fixed. And a motor rotor attached to the rotating shaft of the rotating body, and the motor rotor of the motor is arranged axially offset from the motor stator to generate a first axial force. In addition, an actuator for generating an axial force in a direction opposite to the first axial force is provided.

By thus preliminarily shifting the motor rotor of the motor with respect to the motor stator in the axial direction, a large magnetic shearing force can be generated in the axial direction and an axial force in one direction can be obtained. Therefore, the rigidity in the axial direction can be increased by providing the actuator that generates the axial force in the direction opposite to this axial force.

In a preferred aspect of the present invention, the actuator includes a magnetic member attached to a rotary shaft of the rotating body, and an electromagnet that applies a magnetic attraction force to the magnetic member.
A displacement sensor that measures an axial distance between the electromagnet and the magnetic member, and a control device that supplies a current controlled based on an output signal of the displacement sensor to the electromagnet. .

With this arrangement, the axial position of the rotary shaft can be measured by the displacement sensor and the acting force applied to the rotary shaft can be controlled. Therefore, it is possible to effectively control the vibration in the axial direction by keeping the axial position of the rotary shaft constant.
A magnetic bearing motor having good vibration characteristics can be provided.

In a preferred aspect of the present invention, a disk made of a non-magnetic material having a large electric conductivity is attached to the rotating body, and a magnet is provided so that a magnetic flux passes through the inside of the disk. It is characterized by that. As a result, when the rotating shaft of the rotating body vibrates in the axial direction, the magnetic flux density in the disk changes, and a current flows in the disk due to the electromagnetic induction effect. Vibration current is consumed by this current, and vibration of the rotating shaft can be attenuated. Therefore, it is possible to provide a magnetic bearing motor having stable vibration characteristics in the axial direction.

In this case, it is preferable that the magnet is provided on the outer peripheral portion of the disk. In this way, by providing the magnet on the outer peripheral portion of the disc, it is possible to maximize the change in the magnetic flux in the disc due to the axial vibration, so that it is possible to effectively damp the axial vibration.

A fourth aspect of the present invention is 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 a laser beam, and the above-mentioned. An excimer laser device, comprising: a magnetic bearing motor, wherein the rotating body of the magnetic bearing motor is used as a circulating fan to create a high-speed laser gas flow between the pair of main discharge electrodes.

When a magnetic bearing motor is incorporated in an excimer laser device, it is necessary to install a partition wall on the inner peripheral surface of the stator side (fixed side) element of the magnetic bearing motor in order to protect the element having poor corrosion resistance from the laser gas. There is. Therefore, such an excimer laser device tends to have a complicated structure, but if the magnetic bearing motor according to the present invention is incorporated, it can be inexpensive and simple and is effective.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a magnetic bearing motor according to the present invention will be described in detail with reference to FIGS. 1 to 8, the same or corresponding components are designated by the same reference numerals, and duplicated description will be omitted.

FIG. 1 is a schematic view showing the structure of a magnetic bearing motor according to the first embodiment of the present invention. As shown in FIG. 1, the magnetic bearing motor includes a rotating body 10 such as a rotor (impeller) or a flywheel, and a rotating shaft 20 protruding from both sides of the rotating body 10. Active radial magnetic bearings 30 and 40 are provided on both sides of the rotating body 10, and the radial position of the rotary shaft 20 is controlled by these radial magnetic bearings 30 and 40.

At the end of the rotary shaft 20 on the radial magnetic bearing 30 side, a motor 50 for rotating the rotary body 10 is provided. The motor 50 includes a motor rotor 50 a fixed to the rotating shaft 20 and a motor rotor 5 a fixed to the stator.
0a surrounding the motor stator 50b. A rotational driving force is applied to the rotary shaft 20 by the motor 50.

The radial magnetic bearing 30 is provided with a displacement sensor 30a as a stator side (fixed side) element and an electromagnet having a coil 30c wound around an iron core 30b, and a displacement sensor target 30d as an element on the rotating body 10 side. And an electromagnet target 30e. The displacement sensor target 30d and the electromagnet target 30e are the rotating shaft 2
It is fixed to 0 and faces the displacement sensor 30a and the iron core 30b of the electromagnet, respectively.

Similarly, the radial magnetic bearing 40 is
The displacement sensor 40a is used as a stator side (fixed side) element.
And an electromagnet in which a coil 40c is wound around an iron core 40b, and a displacement sensor target 40d and an electromagnet target 40e are provided as elements on the rotating body 10 side. The displacement sensor target 40d and the electromagnet target 40e are fixed to the rotating shaft 20 and face the displacement sensor 40a and the iron core 40b of the electromagnet, respectively.

Here, the electromagnet target 30e is arranged so as to be displaced toward the rotating body 10 side along the axial direction with respect to the iron core 30b of the electromagnet. Therefore, the radial magnetic bearing 3
By the electromagnet of 0, not only the magnetic attraction force in the radial direction but also the magnetic shearing force (axial force) F1 in the axial direction is generated on the rotating shaft 20.

On the other hand, the electromagnet target 40e is arranged so as to be displaced toward the rotating body 10 side along the axial direction with respect to the iron core 40b of the electromagnet. Therefore, the radial magnetic bearing 40
The electromagnet generates not only a magnetic attraction force in the radial direction but also a magnetic shearing force (axial force) F2 in the axial direction on the rotating shaft 20.

As described above, the axial force F1 generated by the radial magnetic bearing 30 and the axial force F2 generated by the radial magnetic bearing 40 are generated in the opposite directions, and these axial force F1 and axial force F2 act on the rotary shaft 20. Since it is pulled to the left and right, the rigidity in the axial direction is increased. As described above, according to the present embodiment, it is possible to obtain a sufficient axial rigidity while eliminating the axial magnetic bearing and making the structure inexpensive and simple.

FIG. 2 is a schematic view showing the structure of a magnetic bearing motor according to the second embodiment of the present invention. In the first embodiment shown in FIG. 1, the axial force F1 and the axial force F2 are the rotational shaft 2
Although the example of pulling 0 to the left and right has been described, the present embodiment is an example in which the axial force F1 and the axial force F2 push the rotating shaft 20. That is, as shown in FIG. 2, the radial magnetic bearing 30
Of the electromagnet target 30e of the radial magnet bearing 40e is arranged so as to be displaced toward the motor 50 side along the axial direction with respect to the iron core 30b of the electromagnet. Place it on the edge side. As a result, the axial force F1 generated by the radial magnetic bearing 30 and the axial force F2 generated by the radial magnetic bearing 40 are generated in directions opposite to each other, and the axial force F1 and the axial force F2 press the rotary shaft 20. . Therefore, as in the first embodiment described above, the axial rigidity can be increased.

FIG. 3 is a schematic diagram showing the structure of a magnetic bearing motor according to the third embodiment of the present invention. In the present embodiment, the electromagnet target 30e of the radial magnetic bearing 30 is arranged so as to be displaced toward the motor 50 side along the axial direction with respect to the iron core 30b of the electromagnet, and the electromagnet target 40e of the radial magnetic bearing 40 is the iron core of the electromagnet. 40b
In contrast, they are arranged so as to be displaced toward the rotating body 10 side along the axial direction.

An electromagnet actuator 60 is provided at the shaft end of the rotary shaft 20 opposite to the motor 50. The electromagnet actuator 60 includes a disk-shaped magnetic material plate (magnetic member) 60 fixed to the end of the rotary shaft 20.
a, an electromagnet 60b for exerting a magnetic attraction force on the magnetic material plate 60a, a magnetic pole surface of the electromagnet 60b, and the magnetic material plate 60a.
Displacement sensor 60c for measuring the axial distance to the surface.

As described above, the radial magnetic bearing 30 produces an axial magnetic shearing force (axial force) F1, and the radial magnetic bearing 40 produces an axial magnetic shearing force (axial force) F2. The generated axial force F1 and the generated axial force F2 are generated in the same direction (leftward in FIG. 3). Here, the displacement sensor 6 of the electromagnet actuator 60
The sensor output signal of 0c is input to a control device (not shown), and the current controlled by this control device is supplied to the electromagnet 60b of the electromagnet actuator 60. As a result, a magnetic attraction force acts on the magnetic material plate 60a fixed to the end of the rotating shaft 20, and an axial force F3 in the direction opposite to the axial forces F1 and F2 generated by the radial magnetic bearings 30 and 40 is applied to the rotating shaft 2.
Can be made to act on zero.

As described above, the radial magnetic bearings 30, 40
The axial force F1, F2 is generated by generating a force that opposes the axial force F1, F2 generated by the electromagnet actuator 60.
And the axial force F3 are in a state of pressing the rotating shaft 20, and a stronger axial rigidity can be obtained. Also, the rotary shaft 2
Since the axial position of 0 is measured and the force generated by the electromagnet actuator 60 is controlled, the axial position of the rotary shaft 20 can be made constant, and vibration in the axial direction can be further damped. A magnetic bearing motor having good vibration characteristics can be provided.

FIG. 4 is a schematic diagram showing an example in which the magnetic bearing motor shown in FIG. 3 is applied to an excimer laser device. Figure 4
As shown in FIG. 5, a preionization electrode (not shown) for preionizing the laser gas is provided inside the laser container 100 in which a laser gas containing a halogen-based gas, for example, fluorine gas is sealed.
A pair of main discharge electrodes 110 for obtaining a discharge that enables the oscillation of laser light is arranged.

The magnetic bearing motor is a laser container 100.
Which is disposed inside the rotor, and is the rotating body 10 of the magnetic bearing motor.
Is used as a cross-flow fan for creating a high-speed laser gas flow between the pair of main discharge electrodes 110. Laser light extraction windows 120, 120 are provided on the side walls of the laser container 100 at both ends of the pair of main discharge electrodes 110, 110. Laser excitation discharge is performed by applying a high voltage between the pair of main discharge electrodes 110, 110, and laser light is obtained. The generated laser light is extracted to the outside of the laser container 100 via the windows 120, 120 provided on the side wall of the laser container 100.

When the laser-excited discharge described above is performed, the laser gas between the pair of main discharge electrodes 110, 110 deteriorates, and this deterioration deteriorates the discharge characteristics, making it impossible to perform repeated oscillation. Therefore, the once-through fan 10 circulates the laser gas in the laser container 100 to switch the laser gas between the pair of main discharge electrodes 110, 110 for each discharge, thereby performing stable repetitive oscillation.

Here, in order to protect the radial magnetic bearings 30 and 40 and the motor stator 50b of the motor 50, which have poor corrosion resistance to the laser gas, and to prevent the laser gas from being contaminated, the inner peripheral surface of each stator is protected from the laser gas. 13 made of a material having corrosion resistance
It is covered with 1-133. With this configuration, the element on the rotating body 10 side is arranged inside the laser container 100, and the stator side (fixed side) element is isolated from the atmosphere inside the laser container 100.

The iron core 30b of the electromagnet in the radial magnetic bearing 30 and the iron core 40b of the electromagnet in the radial magnetic bearing 40 are not covered with the partitions 131 and 133, respectively, and their surfaces are exposed inside the laser container 100. An iron core 30b of the radial magnetic bearing 30 and a partition wall 131;
The iron core 40b and the partition wall 133 of the radial magnetic bearing 40 are fixed to each other by welding or the like.

With such a configuration, the displacement sensors 30a, 40a and the coil 3 having poor corrosion resistance to laser gas are provided.
0c and 40c never come into contact with the laser gas,
Magnetic bearing iron cores 30b and 40b and electromagnet target 30
The magnetic gap between the e and 40e can be kept small, and the size and efficiency of the device can be reduced.

Since the iron cores 30b and 40b are in contact with the laser gas, for example, permalloy (Fe-Ni alloy containing 30 to 80% Ni) which is a magnetic material having corrosion resistance is used. Further, as the material of the partition walls 131 and 133, a non-magnetic material, such as austenitic stainless steel, which has good corrosion resistance to laser gas and does not adversely affect the magnetic performance of the electromagnet is used.

Electromagnet 60b of electromagnet actuator 60
Is the coil winding 60 in the coil groove provided in the iron core 60d.
The thin disk-shaped partition wall 134 is fixed by welding or the like so that the coil winding 60e does not come into contact with the laser gas. The displacement sensor 60c also has a thin disk-shaped partition wall 13 so as not to come into contact with the laser gas.
5 is fixed by welding or the like, and the displacement sensor 60c is isolated from the atmosphere inside the laser container 100.

Here, since the iron core 60d of the electromagnet 60b is arranged at a position in contact with the laser gas, for example, permalloy (30 to 80) having good corrosion resistance to the laser gas.
Fe-Ni alloy containing% Ni) is used. Further, as the material of the partition walls 134 and 135, a non-magnetic material, such as austenitic stainless steel, which has good corrosion resistance to laser gas and does not adversely affect the magnetic performance of the electromagnet is used.

Magnetic material plate 60 of electromagnet actuator 60
a is fixed to the end of the rotary shaft 20 and is fixed to the laser container 100.
Since it is disposed inside the perimeter, for example, Permalloy (30 to 80), which is a magnetic material having good corrosion resistance against laser gas, is used.
% -Ni alloy) or a magnetic material having a corrosion-resistant protective layer formed on its surface (for example, Ni plating) is preferably used.

FIG. 5 (a) is a schematic view showing the structure of a magnetic bearing motor according to the fourth embodiment of the present invention, and FIG. 5 (b) is a schematic view showing the end portion of the magnetic bearing motor of FIG. 5 (a). Is. In this embodiment, in the second embodiment shown in FIG. 2, a disk 70 made of aluminum or copper (a non-magnetic material having a large electric conductivity) is attached to the shaft end of the rotary shaft 20. It is a thing. Magnets 72 and 74 are provided on the outer peripheral side of the disk 70.

The magnetic flux generated between the magnets 72 and 74 is as shown in FIG.
As shown in (b), it passes through the inside of the disk 70,
When the rotating shaft 20 vibrates in the axial direction, the magnetic flux density at each location in the disk 70 changes, so that a current is generated in the disk 70 by the electromagnetic induction action and energy is consumed. As a result, a damping force for vibration acts on the rotor, so that it is possible to provide a magnetic bearing motor having a characteristic that the amplitude is small and the vibration can be damped. As the magnets 72 and 74, either permanent magnets or electromagnets may be used, but the permanent magnets are preferable in order to reduce the cost.

FIG. 6 is a schematic diagram showing the structure of a magnetic bearing motor according to the fifth embodiment of the present invention, which is a modification of the third embodiment shown in FIG. The radial magnetic bearings 30 and 40 in the present embodiment have the same arrangement as that of the conventional radial magnetic bearings, and the radial magnetic bearings 30 and 40 generate almost no axial force. On the other hand, the motor rotor 50a of the motor 50 is displaced from the motor stator 50b along the axial direction toward the axial end side.

In such a structure, when the motor 50 is powered on and starts rotating, the motor rotor 50
A rotational driving force is applied to the rotary shaft 20 by a and the motor stator 50b. At this time, since the motor rotor 50a of the motor 50 is axially displaced with respect to the motor stator 50b, not only the rotational driving force but also the axial magnetic shearing force (axial force) F4 is generated. Here, the sensor output signal of the displacement sensor 60c of the electromagnet actuator 60 is input to a control device (not shown), and the current controlled by this control device is applied to the electromagnet 60b of the electromagnet actuator 60.
Supply to. As a result, a magnetic attraction force acts on the magnetic material plate 60a fixed to the end of the rotary shaft 20, and an axial force F3 in the direction opposite to the axial force F4 generated by the motor rotor 50 acts on the rotary shaft 20.

As described above, the axial force F4 and the axial force F3 are generated by causing the electromagnet actuator 60 to generate a force that opposes the axial force F4 generated by the motor rotor 50.
As a result, 0 is pressed against each other, and stronger axial rigidity can be obtained. Further, since the axial position of the rotary shaft 20 is measured and the force generated by the electromagnet actuator 60 is controlled, the axial position of the rotary shaft 20 can be made constant, and further the axial vibration can be damped. Therefore, it is possible to provide a magnetic bearing motor having good vibration characteristics.

FIG. 7 is a schematic view showing the structure of a magnetic bearing motor according to the sixth embodiment of the present invention. In the fifth embodiment shown in FIG. 6, the axial force F3 and the axial force F4 are the rotational shaft 2
Although the example of pressing 0 to the left and right has been described, the present embodiment is an example in which the axial force F3 and the axial force F4 pull the rotary shaft 20. That is, as shown in FIG. 7, the motor rotor 50a of the motor 50 is arranged so as to be displaced toward the rotating body 10 side along the axial direction with respect to the motor stator 50b, and the repulsive force F3 is applied to the rotating shaft 20 by the electromagnet actuator 60. I am letting you. As a result, the axial force F4 generated by the motor 50 and the axial force F3 generated by the electromagnet actuator 60 are generated in opposite directions, and the axial force F3 and the axial force F4 pull the rotary shaft 20. Therefore, as in the fifth embodiment described above, the rigidity in the axial direction is increased.

FIG. 8 is a schematic view showing the structure of a magnetic bearing motor according to the seventh embodiment of the present invention. In this embodiment, two radial magnetic bearings 30, 30, 40, 40 and motors 50, 50 are provided on both sides of the rotating body 10, respectively.
And are arranged. Such a configuration is applied when a stronger rotational driving force is required for the rotating body 10.

Here, the electromagnet target 30e of each radial magnetic bearing 40 is arranged so as to be displaced toward the rotating body 10 side along the axial direction with respect to the iron core 30b of the electromagnet. Therefore, by the electromagnets of the radial magnetic bearings 30 and 30,
Not only the magnetic attraction force in the radial direction but also the magnetic shearing forces (axial forces) F5 and F6 in the axial direction are generated on the rotating shaft 20.

On the other hand, the electromagnet target 40e of each radial magnetic bearing 30 is arranged so as to be displaced toward the rotating body 10 side along the axial direction with respect to the iron core 40b of the electromagnet. Therefore, not only the radial magnetic attraction force but also the axial magnetic shearing force (axial force) F7, F8 is generated on the rotating shaft 20 by the electromagnets of the radial magnetic bearings 40, 40.

Thus, the radial magnetic bearings 30, 30
Generated axial force F5, F6 and the radial magnetic bearing 40,
The axial forces F7 and F8 generated by 40 are generated in directions opposite to each other, and the axial forces F5 and F6 and the axial forces F7 and F8 by the two radial magnetic bearings on both sides pull the rotary shaft 20 left and right. Therefore, the rigidity in the axial direction is increased. As described above, even when a plurality of radial magnetic bearings are used, by changing the arrangement of the electromagnet target and the iron core of the radial magnetic bearing so that the axial forces of the rotary shaft 20 are balanced as a whole, a greater axial rigidity can be obtained. Can be obtained. Although the pulling axial forces have been described in the present embodiment, the present invention can be applied to the axial forces that push each other, as in the above-described second embodiment.

In each of the above-described embodiments, an example in which the electromagnet target of the radial magnetic bearing is displaced from the iron core has been described, but this means that the electromagnet target and the iron core are relatively displaced. Needless to say, the iron core may be displaced from the electromagnet target. Similarly, regarding the motor, it is sufficient if the motor stator and the motor rotor are relatively displaced,
The motor stator may be displaced from the motor rotor.

Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above embodiment and may be implemented in various different forms within the scope of the technical idea thereof.

[0058]

As described above, according to the present invention, a large magnetic shearing force is generated in the axial direction by shifting the electromagnet target of the active radial magnetic bearing in advance in the axial direction with respect to the electromagnet. An axial force in one direction can be obtained. Therefore, by staggering the electromagnet target and the electromagnet so as to generate axial forces in mutually opposite directions by the two radial magnetic bearings, it is possible to increase axial rigidity. This makes it possible to obtain a sufficient axial rigidity while eliminating the axial magnetic bearing and making the structure inexpensive and simple.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a structure of a magnetic bearing motor according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a magnetic bearing motor according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a magnetic bearing motor according to a third embodiment of the present invention.

FIG. 4 is a schematic view showing an excimer laser device including the magnetic bearing motor of FIG.

5 (a) is a schematic view showing the structure of a magnetic bearing motor according to a fourth embodiment of the present invention, and FIG. 5 (b) is FIG.
It is the schematic which shows the end part of the magnetic bearing motor of (a).

FIG. 6 is a schematic diagram showing a magnetic bearing motor according to a fifth embodiment of the present invention.

FIG. 7 is a schematic diagram showing a magnetic bearing motor according to a sixth embodiment of the present invention.

FIG. 8 is a schematic diagram showing a magnetic bearing motor according to a seventh embodiment of the present invention.

FIG. 9 is a schematic view showing a conventional magnetic bearing motor.

FIG. 10 is a schematic diagram showing an excimer laser device including a conventional magnetic bearing motor.

[Explanation of symbols]

10 rotating body 20 rotation axis 30,40 radial magnetic bearing 30a, 40a displacement sensor 30b, 40b iron core 30c, 40c coil 30d, 40d displacement sensor target 30e, 40e electromagnet target 50 motor 50a motor rotor 50b motor stator 60 Electromagnetic actuator 60a Magnetic material plate 60b electromagnet 60c displacement sensor 60d iron core 60e coil winding 70 discs 72,74 magnets 100 laser vessels 110 Main discharge electrode 120 Laser light extraction window 131-135 partition wall

Continued front page    (72) Inventor Kazuki Sato             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION F term (reference) 3J102 AA01 BA03 BA18 CA02 CA16                       CA21 DA03 DA09 DA10 DA26                       DB05 DB37 GA13                 5F071 AA06 EE04 FF05 FF09 JJ05                       JJ08                 5H607 BB01 BB14 BB21 CC01 FF04                       GG01 GG20 HH01

Claims (7)

[Claims] 1. A magnetic bearing motor comprising a motor for rotationally driving a rotating body and a plurality of active radial magnetic bearings for rotatably supporting the rotating body, wherein the active radial magnetic bearing is provided on a fixed side. And an electromagnet target made of a magnetic material attached to the rotating shaft of the rotating body, wherein the electromagnet target of at least one active radial magnetic bearing is axially displaced with respect to the electromagnet. Generate a first axial force to displace the electromagnet target of the other active radial magnetic bearing with respect to the electromagnet in a direction opposite to the direction in which the electromagnet target of the at least one active radial bearing is displaced. The magnetic bearing motor is characterized in that the magnetic bearing motor is arranged so as to generate an axial force in a direction opposite to the first axial force. 2. A magnetic bearing motor comprising a motor for rotationally driving a rotating body and a plurality of active radial magnetic bearings for rotatably supporting the rotating body, wherein the active radial magnetic bearing is provided on a fixed side. And an electromagnet target attached to the rotary shaft of the rotating body, wherein the electromagnet targets of two or more active radial magnetic bearings are displaced in the same direction along the axial direction with respect to the electromagnets. A magnetic bearing motor, wherein the magnetic bearing motor is provided with an actuator for generating a first axial force and generating an axial force in a direction opposite to the first axial force. 3. A magnetic bearing motor comprising a motor for rotationally driving a rotating body and a plurality of active radial magnetic bearings for rotatably supporting the rotating body, wherein the motor is a motor stator provided on a fixed side. When,
A motor rotor attached to the rotating shaft of the rotating body, wherein the motor rotor of the motor is arranged axially offset with respect to the motor stator to generate a first axial force; Is a magnetic bearing motor characterized by being provided with an actuator for generating an axial force in the opposite direction. 4. The actuator includes a magnetic member attached to a rotary shaft of the rotating body, an electromagnet that exerts a magnetic attraction force on the magnetic member, and an axial distance between the electromagnet and the magnetic member. The magnetic bearing motor according to claim 2, further comprising: a displacement sensor for measuring, and a control device for supplying a current controlled based on an output signal of the displacement sensor to the electromagnet. 5. A disk made of a non-magnetic material having a high electric conductivity is attached to the rotating body, and a magnet is provided so that a magnetic flux passes through the inside of the disk. Item 5. The magnetic bearing motor according to any one of items 1 to 4. 6. The magnetic bearing motor according to claim 5, wherein the magnet is provided on an outer peripheral portion of the disk. 7. A laser container for enclosing a laser gas, and a pair of main discharge electrodes arranged in the laser container for obtaining an electric discharge capable of oscillating a laser beam. An excimer laser device, comprising: the magnetic bearing motor according to the item (1), wherein the rotating body of the magnetic bearing motor is used as a circulation fan to generate a high-speed laser gas flow between the pair of main discharge electrodes.