JPH0730399U - Turbo molecular pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce radial runout of the rotor as much as possible in an emergency when the rotor support function such as the radial magnetic bearing is lost. [Structure] The second shake preventing means 13 is provided on the tip side of the rotor 2.
To provide. The second shake prevention means 13 includes two sets of permanent magnets 1.
3a, 13b and its two sets of permanent magnets 13
The a and 13b are configured so as to prevent radial runout of the rotor 2 due to mutual attraction. As a result, even in an emergency in which the rotor supporting function such as the radial magnetic bearing portion is lost, the second runout preventing unit 13 is provided on the tip end side of the rotor 2 and the first runner is provided on the rear end side of the rotor 2 as usual. The shake preventing means is configured to prevent a shake in the radial direction of the rotor 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention reduces the radial runout that occurs in the rotor as much as possible during an emergency when the rotor support function of the radial magnetic bearing part or the axial magnetic bearing part is lost, and the adverse effect of such runout, for example, during such an emergency. The present invention relates to a turbo molecular pump that prevents wear of a protective bearing that supports and protects a rotor.

[0002]

[Prior art]

 Conventionally, a turbo molecular pump of this type has a cylindrical rotor 2 rotatably disposed inside a casing 1 as shown in FIG. 5, and a cylindrical rotor 2 is provided between an outer peripheral surface of the rotor 2 and an inner wall surface of the casing 1. Has stator blades 3 and rotor blades 4 arranged alternately along the axis of the rotor 2. The stator blades 3 are attached to the inner wall surface of the casing 1 via spacers 5, and the rotor blades 4 are attached to the rotor 2 Is disposed on the outer peripheral surface of the.

A rotor shaft 6 is provided inside the rotor 2, and the tip end of the rotor shaft 6 is integrally attached to the rotor 2 while being coaxially arranged with the rotor 2. A stator column 7 is arranged between the rotor shaft 6 and the rotor 2.

A radial magnetic bearing portion 8 is disposed between the stator column 7 and the rotor shaft 6 on the outer peripheral surface side of the tip end of the rotor shaft 6, and the radial magnetic bearing portion 8 includes a radial sensor 8 a and a radial sensor 8 a. The radial sensor 8a is formed of the directional electromagnet 8b, the radial sensor 8a detects the radial displacement of the rotor shaft 6, and the radial electromagnet 8b is excited based on the detection result of the radial displacement sensor 8a. The rotor 2 is configured to be supported in the radial direction by a magnetic force through the rotor shaft 6 along the coordinate axis X and the coordinate axis Y intersecting with the coordinate axis X.

An axial magnetic bearing portion 9 is provided between the stator column 7 and the rotor shaft 6 on the outer peripheral surface side of the rear end of the rotor shaft 6, and the axial magnetic bearing portion 9 includes the thrust disk 9 a and the axial direction. The thrust disk 9a is formed integrally with the outer peripheral surface of the rotor shaft 6 while the sensor 9b and the axial electromagnet 9c are formed. The axial sensor 9b detects the axial displacement of the rotor shaft 6. The axial electromagnet 9c is located on the surface side of the thrust disk 9a and is excited based on the detection result of the axial sensor 9b. The magnetic force of the excitation causes the thrust disk 9a and the rotor shaft 6 to pass through the rotor 2 Are supported in the axial direction (coordinate axis Z direction).

On the rear end side of the rotor 2, a first shake prevention means 10 is provided in the vicinity of the axial magnetic bearing portion 9, and the first shake prevention means 10 includes a rotor 2 and a rotor shaft 6. It is formed of two sets of permanent magnets 10a and 10b that prevent radial swinging and repel each other. One permanent magnet 10a is embedded on the back surface side of the thrust disk 9a, and the other permanent magnet 10a is embedded. The permanent magnet 10b is arranged so as to face the one permanent magnet 10a.

A motor 11 is arranged between the radial magnetic bearing portion 8 and the axial magnetic bearing portion 9 so that the motor 11 integrally rotates with the rotor shaft 6 to rotate the rotor 2 about its axis. Is configured.

In such a turbo molecular pump, when the rotor 2 rotates at a high speed, a molecular flow is induced between the stator blade 3 and the rotor blade 4, and the molecules are exhausted from the intake port 1a to the exhaust port 1b. When the operation is performed and a power failure or a failure during the operation causes the control of supporting the rotor 2 in the radial magnetic bearing portion 8 or the axial magnetic bearing portion 9 in the radial direction or the axial direction, the radial magnetic bearing portion cannot be controlled. 8 or when the rotor supporting function of the axial magnetic bearing portion 9 is lost, a part of the rotor shaft 6 contacts the protective bear ring 12, and the protective bearing 12 is configured to support and protect the rotor 2. ing.

[0009]

[Problems to be solved by the device]

 However, in the conventional turbo molecular pump as described above, only the shake prevention means 10 is provided on the rear end side of the rotor 2, so that the radial magnetic bearing portion 8 or the axial magnetic bearing portion 9 is supported by the rotor. In an emergency when the function is lost, the radial deflection of the rotor 2 is prevented because the radial deflection of the rotor 2 is not prevented and the radial deflection of the rotor 2 is prevented. Not only has a large runout, but also the rotor shaft 6 integrated with the rotor 2 largely shakes in the radial direction, which causes a part of the rotor shaft 6 to vigorously contact the protective bearing 12, resulting in wear of the protective bearing 12. However, there is a problem that the life of the protective bearing 12 is short.

The present invention has been made in view of the above circumstances, and its purpose is to provide a radial direction that occurs in a rotor in an emergency when the rotor supporting function of the radial magnetic bearing portion or the axial magnetic bearing portion is lost. This is to reduce the runout of the rotor as much as possible and prevent the adverse effects of the runout, such as wear of the protective bearing that supports and protects the rotor in such an emergency.

[0011]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a rotor rotatably arranged inside a casing, and stator blades that are alternately provided along an axis of the rotor and fixed to an inner wall surface of the casing. And a rotor blade disposed on the outer peripheral surface of the rotor, a radial magnetic bearing portion that radially supports the rotor, an axial magnetic bearing portion that axially supports the rotor, and an axial center of the rotor. A turbo molecular pump including a motor for rotating the rotor and a first shake prevention unit provided on the rear end side of the rotor and for preventing radial shake of the rotor, wherein the rotor is provided on the front end side of the rotor. A second shake preventing means for preventing the shake in the radial direction of the is provided.

[0012]

According to the present invention, the second runout preventing means is provided at the front end side of the rotor, and the rear end of the rotor is provided even in an emergency when the rotor supporting function of the radial magnetic bearing part or the axial magnetic bearing part is lost. As for the side, the first shake preventing means prevents the shake in the radial direction generated in the rotor as in the conventional case.

[0013]

【Example】

 Hereinafter, an embodiment of a turbo molecular pump according to the present invention will be described in detail with reference to FIGS.

It should be noted that the basic configuration of the turbo molecular pump shown in FIG. 1, that is, having a rotor 2 rotatably arranged inside a casing 1, and disposing a rotor 2 between the rotor 2 and the casing 1. The stator blades 3 and the rotor blades 4 are alternately provided along the axis of, the stator blades 3 are fixed to the inner wall surface of the casing 1, and the rotor blades 4 are arranged on the outer peripheral surface of the rotor 2. The radial magnetic bearing 8 supports the rotor 2 in the radial direction, and the axial magnetic bearing 8 supports the rotor 2 in the axial direction. However, the motor is configured to rotate the rotor 2 around the axis, and the rear end side of the rotor 2 is provided with a first runout preventing means (not shown), and the first runout is provided. The preventive measures are Since it is the same as the conventional one in that it is configured so as to prevent the vibration of the rotor 2 in the radial direction, the same members are denoted by the same reference numerals and detailed description thereof will be omitted.

The turbo molecular pump shown in the figure has a second shake prevention means 13 on the tip side of the rotor 2, and the second shake prevention means 13 is provided on the tip end surface of the stator column 7 and the inner bottom surface of the rotor 2. 2 and is formed of two sets of permanent magnets 13a and 13b as shown in FIG. 2, one of the permanent magnets 13a is integrated with the tip surface of the stator column 7 and the other permanent magnet 13b. Is integrally fixed to the inner bottom surface of the rotor 2 via the flange portion 6a of the rotor shaft 6.

The two pairs of permanent magnets 13 a and 13 b are arranged so that the different poles face each other, and are arranged in a pair of inner and outer rings along the outer peripheral surface of the rotor shaft 6.

That is, the second shake prevention means 13 restrains the rotor 2 in the radial direction by mutual attraction between the two sets of permanent magnets 13a and 13b, and prevents the shake in the rotor 2 in the radial direction. Is configured to.

Next, the operation of the turbo-molecular pump configured as described above will be described based on FIGS. 1 and 2 and with reference to FIG.

According to this turbo molecular pump, when the rotor 2 rotates at high speed as shown in FIGS. 1 and 2, a molecular flow is induced between the stator blade 3 and the rotor blade 4, and the exhaust gas is exhausted from the intake port 1a. The operation of exhausting molecules to the side of the mouth 1b (see FIG. 4) is performed.

During such an operation, due to a power failure or a failure, the control for supporting the rotor 2 in the radial magnetic bearing portion 8 or the axial magnetic bearing portion 9 (see FIG. 5) in the radial direction or the axial direction becomes impossible. Even when the rotor supporting function of the radial magnetic bearing portion 8 or the axial magnetic bearing portion 9 is lost, the second runout preventing means 13 is provided at the front end side of the rotor 2 and the rear end side of the rotor 2 is provided as usual. The first shake prevention means 10 (see FIG. 5) restrains the rotor 2 in the radial direction, and prevents the shake in the rotor 2 in the radial direction.

Therefore, not only the rear end side of the rotor 2 but also the front end side of the rotor 2 does not largely swing in the radial direction, the radial runout occurring in the rotor 2 is reduced as much as possible, and the rotor 2 and the rotor 2 are integrated. The rotor shaft 6 does not largely swing in the radial direction, and the problem that a part of the rotor shaft 6 is vigorously in contact with the protective bearing 12 is solved, and wear of the protective bearing ring 12 can be prevented. The life of the product can be extended.

FIG. 3 shows another embodiment of the turbo molecular pump according to the present invention. Since the basic configuration of the turbo molecular pump shown in FIG. A reference numeral is given and detailed description thereof is omitted.

This turbo molecular pump has a second shake prevention means 13 on the tip side of the rotor 2, and the second shake prevention means 13 is provided between the outer peripheral surface of the stator column 7 and the inner peripheral surface of the rotor 2. The permanent magnets 13a and 13b are positioned and formed from two sets of permanent magnets 13a and 13b as shown in FIG. 4. One permanent magnet 13a is integrally formed on the outer peripheral surface of the stator column 7, and the other permanent magnet 13b is formed on the rotor 2. It is integrally fixed to the inner peripheral surface.

The two sets of permanent magnets 13a and 13b are provided so that the same poles face each other as in the above embodiment, and are arranged in a pair of inner and outer rings along the outer peripheral surface of the rotor shaft 6. Has been done.

In other words, the second runout preventing means 13 in this embodiment also binds the rotor 2 in the radial direction by the repulsive forces of the two sets of permanent magnets 13a and 13b, as in the above embodiment, and the rotor 2 It is configured to prevent radial runout that occurs in the.

Even in this turbo molecular pump, the rotor supporting function of the radial magnetic bearing portion 8 or the axial magnetic bearing portion 9 (see FIG. 5) is lost due to a power failure or a failure during the operation. Even at this time, the second runout preventing means 13 is attached to the front end side of the rotor 2, and the first runout preventing means 10 (see FIG. 5) is attached to the rear end side of the rotor 2 as in the prior art. It is constrained in the radial direction to prevent radial runout of the rotor 2.

Therefore, according to the turbo molecular pump of the above-described embodiment, even in an emergency when the rotor supporting function of the radial magnetic bearing portion or the axial magnetic bearing portion is lost, the second shake prevention means is provided on the tip side of the rotor. However, on the rear end side of the rotor, the first runout preventing means respectively prevent radial runout that occurs in the rotor as in the conventional case, so that not only the rear end side of the rotor but also the front end side largely swings in the radial direction. Not only does the radial runout that occurs in the rotor decrease as much as possible, but the rotor shaft integrated with the rotor does not swing significantly in the radial direction, and part of the rotor shaft is used as protective bearing. The problem of violent contact is eliminated, the wear of the protective bearing can be prevented, and the life of the protective bearing can be extended.

[0028]

[Effect of device]

 In the turbo molecular pump according to the present invention, the radial magnetic bearing portion or the radial magnetic bearing portion is provided because the second deflection preventing means for preventing the radial deflection of the rotor is provided on the tip side of the rotor as described above. Even in an emergency when the rotor support function of the axial magnetic bearing part is lost, the second runout prevention means is attached to the rotor front end side, and the first runout prevention means is attached to the rotor rear end side. Since the radial runout that occurs is prevented, not only the rear end side of the rotor but also the front end side does not largely swing in the radial direction, and the radial runout that occurs in the rotor is of course reduced as much as possible. Therefore, it is possible to prevent adverse effects due to the runout, such as wear of the protective bearing that supports and protects the rotor in such an emergency.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a turbo molecular pump according to the present invention.

FIG. 2 is an enlarged view of the vicinity of a portion A shown in FIG.

FIG. 3 is a sectional view showing another embodiment of the turbo molecular pump according to the present invention.

FIG. 4 is an enlarged view of the vicinity of a B part shown in FIG.

FIG. 5 is a sectional view of a conventional turbo molecular pump.

[Explanation of symbols]

 2 Rotor 3 Stator Blade 4 Rotor Blade 8 Radial Magnetic Bearing 9 Axial Magnetic Bearing 10 First Shake Prevention Means 11 Motor 13 Second Shake Prevention Means

Claims (1)

[Scope of utility model registration request] 1. A rotor rotatably arranged inside a casing, stator blades alternately provided along an axis of the rotor and fixed to an inner wall surface of the casing, and an outer peripheral surface of the rotor. A rotor blade provided, a radial magnetic bearing portion that supports the rotor in the radial direction, an axial magnetic bearing portion that supports the rotor in the axial direction, a motor that rotates the rotor around the axis, and a rotor A turbo molecular pump provided on a rear end side and having a first shake prevention means for preventing a radial shake of the rotor, wherein a second shake preventing means for preventing a radial shake of the rotor is provided on a front end side of the rotor. A turbo molecular pump, characterized in that it is provided with a shake prevention means.