JP4763145B2 - Molecular pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molecular pump, for example, a turbo molecular pump used in a semiconductor manufacturing apparatus or the like.
[0002]
[Prior art]
With recent rapid progress in science and technology, vacuum pumps with high performance and high reliability have been demanded in various fields. In general, these vacuum pumps include molecular pumps such as a thread groove pump and a turbo molecular pump.
These molecular pumps are widely used in various fields of industry and academic research, such as exhaust of semiconductor devices and exhaust of electron microscopes and particle accelerators.
[0003]
The turbo-molecular pump is composed of a turbo-molecular pump portion having rotor blades and stator blades on the intake port side of a casing (exterior body), a rotor having a cylindrical outer peripheral surface on the exhaust port side, and an inner periphery facing the rotor. There is one constituted by a thread groove type pump part constituted by a stator having grooves formed on the surface in a spiral shape.
The rotor shaft is formed with a motor portion formed of, for example, a DC brushless motor, and the rotor can rotate at high speed.
[0004]
In the turbo molecular pump section, the stages formed by the rotor blades and the stages formed by the stator blades are alternately arranged. When the rotor is rotated at a high speed by the motor unit, gas is sucked from the intake port by the action of the rotor blades and the stator blades. The sucked gas is sent to the thread groove type pump unit and discharged from the exhaust port while being guided by the groove formed in the stator.
[0005]
[Problems to be solved by the invention]
  However, since the rotor rotates at a high speed of, for example, 40,000 revolutions per minute, when the rotor breaks, the rotor contacts the stator with a large kinetic energy and decelerates rapidly. For this reason, the stator receives a large force due to the collision, and a large torque is applied to the bolts fixing the turbo molecular pump and the piping connected to the intake and exhaust ports of the turbo molecular pump,thisThere is a case where a heavy load is applied to these parts.AhIt was.
  That is, if the rotating body (rotor) is damaged while the turbo molecular pump is in operation and scattered around it, the rotating body will collide with the casing including the base with a large amount of energy. Or connected to the air inlet / outletPiping, etc.In some cases, a large torque is applied to the product, causing a problem.
  On the other hand, the conventional method has not been sufficient for preventing the influence on peripheral devices caused by the breakage of the rotating body.
[0006]
Therefore, an object of the present invention is to provide a molecular pump that quickly stops the molecular pump even when the rotor is broken during operation, and has little influence on the members connected to the molecular pump.
[0007]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the present inventionmouthFormed on the other end side, a rotor rotatably supported inside the exterior body, a motor for rotating the rotor, and a periphery of the rotor And a stator in which a cavity having a cross-sectional shape inclined at a predetermined angle with respect to the radial direction of the rotor is formed (first pump). Constitution).
  By providing such a cavity in the stator, when the rotor breaks down and collides with the stator, the stator can be smoothly crushed and the impact from the rotor can be absorbed.
  In order to achieve the above object, the present invention provides an intake air on one end side.mouthFormed on the other end side, a rotor rotatably supported in the exterior body, a motor for rotating the rotor, and a periphery of the rotor And a shock-absorbing member which is disposed on the outer periphery of the stator and in which a hollow portion having a cross-sectional shape inclined at a predetermined angle with respect to the radial direction of the rotor is formed. A second molecular pump is provided (second configuration).
  Thus, a member for absorbing an impact can be disposed on the outer peripheral portion of the stator.
  The predetermined cross-sectional shape in the first configuration or the second configuration is a substantially parallelogram, and one of two opposing sides is substantially parallel to a tangent in the rotational direction of the rotor, Of the pair of sides, the side closer to the rotor can be configured to be positioned in the rotational direction of the rotor than the side farther from the rotor (third configuration). When the cross-sectional shape is formed in this way, when the rotor breaks down and collides with the stator, the cross section of the substantially parallelogram can be smoothly crushed.
  Further, the predetermined cross-sectional shape in the first configuration or the second configuration is substantially an ellipse, and of the two intersections of the major axis of the approximate ellipse and the approximate ellipse, the intersection closer to the rotor is Further, it may be configured to be positioned in the rotational direction of the rotor from the intersection far from the rotor (fourth configuration).
  By arranging the elliptical cross-sectional shape in this way, when the rotor breaks and collides with the stator, the ellipse collapses smoothly in the minor axis direction.
  In order to achieve the above object, the present invention provides an intake air on one end side.mouthFormed on the other end side, a rotor rotatably supported in the exterior body, a motor for rotating the rotor, and a periphery of the rotor A cavity formed between the stator and the cylindrical member, and a cylindrical member having an inner peripheral surface disposed on the outer peripheral portion of the stator with a predetermined gap therebetween. In the outer periphery of the stator or the cylindrical memberInsideThere is provided a molecular pump characterized in that a protrusion inclined at a predetermined angle with respect to the radial direction of the rotor is provided on at least one of the peripheral portions (fifth configuration).
  When the protrusion is formed on the stator, the protrusion has an arc shape that is convex in the rotation direction of the rotor. When the protrusion is formed on the cylindrical member, the direction is opposite to the rotation direction of the rotor. It can be formed to have a convex arc shape.
  The hollow portion of any one configuration from the first configuration to the fifth configuration is formed in the axial direction of the rotor and can be configured such that at least one end is closed (sixth configuration) Constitution).
  The shock absorbing material can be filled into the cavity of any one configuration from the first configuration to the sixth configuration (seventh configuration).
  The impact absorbing ability can be further enhanced by filling the cavity with the impact absorbing material.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
In this embodiment, a deformable gap is formed inside a threaded spacer.
More specifically, a space between the threaded spacer, the casing, and the base is provided with an appropriate inclination with respect to the radial direction so that smooth deformation is possible, so that the threaded spacer can be plastically deformed. Is.
The gap is formed with a cross section (parallelogram, ellipse, etc.) having an angle inclined with respect to the radial direction so as to be smoothly deformed by collision with the broken rotor lower portion 29.
In the turbo molecular pump in which the intake port side is a turbo molecular pump part composed of rotor blades and stator blades, and the exhaust port side is a thread groove type pump part composed of a rotor and a thread groove spacer, the rotor is destroyed. Usually arises from the threaded portion of the threaded pump section. The thread part in which a crack has occurred partially expands due to centrifugal force and contacts the threaded spacer. On the other hand, since the threaded spacer is formed with a hole inclined with respect to the radial direction, it is smoothly deformed. The energy transferred from the rotor to the base and casing is absorbed by the plastic deformation.
An impact absorbing material such as rubber or urethane having viscous resistance can be inserted into the gap provided in the threaded spacer.
(First embodiment)
FIG. 1 is a view showing the turbo molecular pump 1 according to the first embodiment, and is a view showing a cross-sectional view of the rotor shaft 11 in the axial direction.
In this embodiment, a turbo molecular pump including a turbo molecular pump unit and a thread groove type pump unit is used as an example of the molecular pump.
Although not shown in FIG. 1, the intake port 6 of the turbo molecular pump 1 is, for example, a conductance valve (a valve that changes the cross-sectional area of the flow path of the piping to adjust the conductance of exhaust gas, that is, the ease of flow). The exhaust port 19 is connected to an auxiliary pump or the like through a vacuum device such as a semiconductor manufacturing device.
[0009]
The casing 16 that forms the exterior body of the turbo molecular pump 1 has a cylindrical shape, and the rotor shaft 11 is installed at the center thereof. The casing 16 forms an exterior body of the turbo molecular pump 1 together with a base 27 described later.
Magnetic bearing portions 8, 12, and 20 are provided at the upper, lower, and bottom portions in the axial direction of the rotor shaft 11, respectively. The rotor shaft 11 is supported by the magnetic bearing portions 8 and 12 in a non-contact manner in the radial direction (the radial direction of the rotor shaft 11), and is supported by the magnetic bearing portion 20 in a non-contact manner in the thrust direction (the axial direction of the rotor shaft 11). ing. These magnetic bearing portions constitute a so-called five-axis control type magnetic bearing, and the rotor shaft 11 rotates around the axis.
[0010]
  In the magnetic bearing portion 8, for example, four electromagnets are arranged around the rotor shaft 11 so as to face each other every 90 °.
  An electromagnet target 32 is formed at a portion constituting the magnetic bearing portion 8 on the rotor shaft 11. The electromagnet target 32 is formed of a laminated steel plate in which a large number of steel plates such as silicon steel having an insulating film formed on the surface thereof are laminated. This is installed to suppress the generation of eddy current on the rotor shaft 11 due to the magnetic field generated in the magnetic bearing portion 8.
  When an eddy current is generated in the rotor shaft 11, the rotor shaft 11 generates heat and an eddy current loss occurs, resulting in a reduction in efficiency. However, this can be prevented by configuring the electromagnet target 32 with a laminated steel plate..
  In the magnetic bearing portion 8, the electromagnet target 32 is attracted by the magnetic force of the electromagnet, and the rotor shaft 11 is magnetically levitated in the radial direction.
[0011]
A radial sensor 9 is formed in the vicinity of the magnetic bearing portion 8. The radial sensor 9 includes, for example, a coil disposed around the rotor and a radial sensor target 31 formed on the rotor shaft 11.
The coil forms a part of a transmission circuit of a control unit (not shown), and the amplitude of the signal changes depending on the distance between the coil and the radial sensor target 31. Accordingly, the displacement of the rotor shaft 11 is detected.
[0012]
The radial sensor target 31 is formed of a laminated steel plate similarly to the electromagnet target 32.
Based on the signal from the radial sensor 9, a control unit (not shown) feedback-controls the magnetic force generated by the magnetic bearing unit 8.
Other sensors for detecting the displacement of the rotor shaft 11 include a capacitance type and an optical type.
[0013]
Since the configuration and operation of the magnetic bearing portion 12 and the radial sensor 13 are the same as those of the magnetic bearing portion 8 and the radial sensor 9, respectively, description thereof will be omitted.
[0014]
The magnetic bearing portion 20 provided at the lower end of the rotor shaft 11 includes a disk-shaped metal disk 26, electromagnets 14 and 15, and a thrust sensor 17.
The metal disk 26 is made of a high permeability material such as iron and is fixed perpendicularly to the rotor shaft 11 at the center thereof. The electromagnet 14 is installed on the metal disk 26, and the electromagnet 15 is installed below. The electromagnet 14 attracts the metal disk 26 upward by magnetic force, and the electromagnet 15 attracts the metal disk 26 downward.
[0015]
Similar to the radial sensors 9 and 13, the thrust sensor 17 is configured by a coil, for example, detects the displacement of the rotor shaft 11 in the thrust direction, and transmits this to a control unit (not shown).
The control unit can detect the displacement of the rotor shaft 11 in the thrust direction based on the signal received from the radial sensor 13.
[0016]
When the rotor shaft 11 moves in one of the thrust directions and is displaced from a predetermined position, the control unit adjusts the excitation current of the electromagnets 14 and 15 so as to correct this displacement, and returns the rotor shaft 11 to the predetermined position. To work.
The control unit can magnetically levitate the rotor shaft 11 to a predetermined position in the thrust direction by this feedback control and hold it.
As described above, the rotor shaft 11 is held in the radial direction by the magnetic bearing portions 8 and 12, and is held in the thrust direction by the magnetic bearing portion 20, so that it has only a degree of freedom of rotation around the axis. Be supported.
[0017]
  A motor unit 10 is provided in the middle of the magnetic bearing units 8 and 12 of the rotor shaft 11.
  In the present embodiment, as an example, the motor unit 10 is configured by a DC brushless motor.
  A permanent magnet is fixed around the portion of the rotor shaft 11 constituting the motor unit 10. For example, the permanent magnet is fixed so that the N pole and the S pole are arranged around the rotor shaft 11 every 180 °. Around the permanent magnet, a predetermined clearance from the rotor shaft 11 is provided, for example, six electromagnets with respect to the axis of the rotor shaft 11 every 60 °.SymmetryAnd so as to face each other.
[0018]
On the other hand, the turbo-molecular pump 1 includes a sensor (not shown) that detects the rotation speed and rotation angle (phase) of the rotor shaft 11, whereby the control unit positions the magnetic pole of the permanent magnet fixed to the rotor shaft 11. Can be detected.
The control unit sequentially switches the current of the electromagnet of the motor unit 10 according to the detected position of the magnetic pole, and generates a rotating magnetic field around the permanent magnet of the rotor shaft 11.
The permanent magnet fixed to the rotor shaft 11 follows this rotating magnetic field, whereby the rotor shaft 11 rotates.
[0019]
A rotor 24 is attached to the upper end of the rotor shaft 11 with a plurality of bolts 25.
In the present embodiment, as an example, a portion of the rotor 24 from the middle to the intake port 6 side, that is, a substantially upper half portion in the figure, is a turbo molecular pump portion composed of rotor blades 21 and stator blades 22. In the figure, it is assumed that the substantially lower half portion is a thread groove type pump portion constituted by a spacer 5 which is a threaded spacer. The structure of the turbo molecular pump is not limited to this. For example, the turbo molecular pump may be configured by a thread groove type pump from the inlet 6 side to the exhaust port 13 side.
[0020]
In the turbo molecular pump portion, the rotor blades 21 made of aluminum alloy or the like are attached to the rotor 24 at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 11, and are mounted in a plurality of stages radially from the rotor 24. is there. The rotor blade 21 is fixed to the rotor 24 and is rotated at a high speed together with the rotor shaft 11.
On the inlet side of the casing 16, a stator blade 22 made of an aluminum alloy or the like is inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 11, and the step of the rotor blade 21 toward the inner side of the casing 16. And are arranged alternately.
[0021]
The spacer 23 is a ring-shaped member and is made of a metal such as aluminum, iron, or stainless steel.
The spacers 23 are disposed between the stages formed by the stator blades 22 and hold the stator blades 22 at predetermined positions.
[0022]
When the rotor 24 is driven by the motor unit 10 and rotates together with the rotor shaft 11, exhaust gas is sucked from the intake port 6 by the action of the rotor blades 21 and the stator blades 22.
The exhaust gas taken in from the intake port 6 passes between the rotor blades 21 and the stator blades 22 and is sent to the thread groove type pump unit.
[0023]
The thread groove type pump portion is composed of a rotor lower portion 29, a spacer 5, and the like. In the present embodiment, the thread groove is formed in the spacer 5.
The rotor lower portion 29 is constituted by a portion having a cylindrical outer peripheral surface formed in a substantially lower half portion of the rotor 24, and the outer peripheral surface extends to a region close to the inner peripheral surface of the spacer 5.
The stator of the thread groove type pump part is constituted by a spacer 5. The spacer 5 is a cylindrical member made of, for example, a metal such as aluminum, stainless steel, or iron, and a plurality of helical thread grooves 7 are formed on the inner peripheral surface thereof.
[0024]
The direction of the spiral of the thread groove 7 is a direction in which molecules of the exhaust gas are transferred toward the exhaust port 19 when the molecules of the exhaust gas move in the rotation direction of the rotor 24.
When the rotor 24 is driven and rotated by the motor unit 10, the exhaust gas sent from the turbo molecular pump unit is transferred toward the exhaust port 19 while being guided by the screw groove 7.
[0025]
The spacer 5 is formed with a deformable cavity 3 (gap). The gap has a cross section having a shape inclined at an angle with respect to the radial direction so as to be smoothly deformed by the impact of the broken rotor lower portion 29.
The spacer 5 is deformed smoothly when the rotor lower portion 29 is broken while the turbo molecular pump 1 is in operation and collides with the spacer 5, and the force and torque generated by the breakage are alleviated.
[0026]
In the present embodiment, a threaded spacer having a thread groove 7 formed on the stator side is disposed and the outer peripheral surface of the rotor lower portion 29 is cylindrical, but conversely, a thread groove is formed on the outer peripheral surface of the rotor. It can also be a turbo molecular pump.
[0027]
The base 27 is a disk-like member that forms the base of the turbo molecular pump 1 and is made of a metal such as stainless steel, aluminum, or iron.
As for the base 27, the casing 16 is joined to the upper end part of an outer edge part, and the spacer 5 is installed in the inner side. A mechanism for holding the rotor shaft 11 such as the magnetic bearings 8, 12, 20 and the motor unit 10 is installed at the center.
[0028]
A water cooling pipe 18 for circulating cooling water is attached to the lower part of the base 27, and heat exchange is efficiently performed between the water cooling pipe 18 and the base 27.
The heat transferred to the base 27 can be efficiently discharged to the outside of the turbo molecular pump 1 by the cooling water circulating in the water cooling pipe 18, so that the turbo molecular pump 1 is heated and exceeds the allowable temperature. Can be prevented.
[0029]
The water cooling pipe 18 constitutes a water cooling system together with a water pump (not shown) and a heat exchanger (not shown). The cooling water in the water cooling pipe 18 circulates in the water cooling system by the action of a water pump.
The heat obtained by the heat exchange of the cooling water with the base 27 is released to the outside of the water cooling system such as in the atmosphere by a heat exchanger.
As a result, the cooling water is cooled and sent again to the turbo molecular pump 1 by the water pump.
[0030]
When the turbo molecular pump 1 breaks during operation, the breakage of the rotor lower portion 29 is the starting point, and the breakage after that often continues. Therefore, in the present embodiment, the spacer 5 is provided with a mechanism for reducing the force and torque that the rotor lower portion 29 applies to the turbo molecular pump 1.
[0031]
FIG. 2 is a view showing a cross section of the cavity 3 of the spacer 5 as viewed in the XX direction shown in FIG.
The thread groove portion of the spacer 5 and the rotor lower portion 29 are not shown. The rotor lower part 29 rotates at high speed in the direction of the arrow.
[0032]
A cavity 3 is formed inside the spacer 5. Various cross-sectional shapes of the cavity 3 are conceivable. In this embodiment, a large number of cavities 41, 41, 41,... Having a parallelogram-shaped cross-section are concentric in the axial direction of the rotor shaft 11. It is assumed that it is formed.
When the turbo molecular pump 1 is operated, a pressure difference is generated between the upper end and the lower end of the cavities 41, 41, 41, ..., but the upper ends of the cavities 41, 41, 41, ... are closed. The air flow generated in the cavities 41, 41, 41, ... due to the pressure difference is prevented.
[0033]
A portion 40 between the parallelogram and the parallelogram in the cross section of the hollow portions 41, 41, 41,... Is a kind of beam for holding the inner peripheral portion 39 and the outer peripheral portion 38 of the buffer portion. The portion 40 is formed to be inclined in the rotational direction of the rotor lower portion 29 when viewed in the direction from the outer peripheral portion 38 to the inner peripheral portion 39 of the spacer 5.
[0034]
When the rotor lower portion 29 breaks during high-speed rotation and collides with the inner peripheral surface of the spacer 5, the movement of the fragments of the rotor lower portion 29 has a radial component and a rotational component of the rotor lower portion 29. Therefore, the spacer 5 receives a radial force (impact) from the rotor lower portion 29 and a torque acting in the rotation direction of the rotor lower portion 29.
[0035]
  The spacer 5 is smoothly deformed by an impact from the rotor lower portion 29, and at that time, the outward force and torque are absorbed by the following mechanism.
  CavityThe parallelogram having a cross-sectional shape of 41, 41, 41,... Has a shape in which the inner peripheral side of the spacer 5 is moved in the rotational direction of the rotor lower part 29 from the outer peripheral side. When the inner peripheral surface of 5 receives torque from the rotor lower portion 29, the shape of the parallelogram is smoothly collapsed.
[0036]
When the rotor lower portion 29 breaks and collides with the inner peripheral surface of the spacer 5, the spacer 5 receives a radial force and torque.
When the spacer 5 receives a radial force and torque, the cross-sectional shape of the parallelogram of the cavities 41, 41, 41,... Is crushed. It will spread in the radial direction while rotating in the direction of rotation.
The radial force that the spacer 5 receives from the rotor lower portion 29 is absorbed by plastic deformation of the inner peripheral portion 39 in the radial direction.
On the other hand, the torque is absorbed by the inner peripheral portion 39 being rotationally deformed in the rotational direction of the rotor lower portion 29.
[0037]
That is, since the inner peripheral portion 39 of the spacer 5 and the portion 40 serving as the beam holding the outer peripheral portion 38 are inclined in the rotational direction of the rotor lower portion 29 from the outer peripheral portion 38 to the inner peripheral portion 39 of the spacer 5, When the rotor lower portion 29 collides with the spacer 5, the beam portion 40 falls down smoothly, and the radial force and torque of the rotor 24 can be absorbed.
In other words, the spacer 5 functions as a brake that brakes the rotor 24.
[0038]
When the rotor lower portion 29 breaks, the torque that the rotor 24 has exerts a large load on a member such as a bolt that fixes the turbo molecular pump 1 via the casing 16 or the like. Therefore, the load which these components receive by the buffer action of the spacer 5 can be reduced.
[0039]
The turbo molecular pump 1 configured as described above operates as follows.
First, the magnetic bearing portions 8, 12 and 20 are driven to magnetically float the rotor shaft 11.
The radial displacement of the rotor shaft 11 is detected by radial sensors 9 and 13, and the displacement of the rotor shaft 11 in the thrust direction is detected by a thrust sensor 17. A control unit (not shown) performs feedback control of the excitation current supplied to the electromagnets of the magnetic bearing units 8, 12, and 20 so that the rotor shaft 11 is held at a predetermined position by the detected displacement of the rotor shaft 11.
[0040]
Next, the control unit drives the motor 10 to rotate the rotor shaft 11, the rotor 24, and the rotor blade 21 at a high speed.
Then, the exhaust gas is sucked into the turbo molecular pump portion from the intake port 6 by the action of the rotor blade 21 and the stator blade 22.
The exhaust gas sucked into the turbo molecular pump unit is sent to the thread groove type pump unit.
The exhaust gas sent to the thread groove type pump unit is transferred along the thread groove 7 by the rotation of the rotor 24, and is exhausted from the exhaust port 19 to the outside of the turbo molecular pump 1.
[0041]
  When the turbo molecular pump 1 is in operation, when the rotor lower portion 29 is broken and the rotor lower portion 29 expands due to a large centrifugal force accompanying high-speed rotation, these expanded portions have a large kinetic energy and the inner peripheral surface of the spacer 5. Collide with.
  These partsHaRadial force and torque on the inner surface of the pacer 5TheEffect. The hollow portions 41, 41, 41,... Are crushed and plastically deformed by these forces and torques.
  At that time, the force applied to the spacer 5 by the rotor lower portion 29 and the torque of the rotor 24 are absorbed by the spacer 5, and the rotor 24 stops without adversely affecting the fixed part of the turbo molecular pump 1 or the outside such as piping. To do.
[0042]
In the present embodiment, the inside of the cavity portions 41, 41, 41,... Is a cavity, but the present invention is not limited to this. For example, the inside of the cavity portions 41, 41, 41,. Or shock absorbing material such as urethane may be filled.
Furthermore, the cross-sectional shape of the hollow portions 41, 41, 41,... Is not limited to a parallelogram, and for example, a hexagonal shape or an ellipse is quickly deformed with respect to the force and torque received from the rotor lower portion 29. Other shapes may be used.
[0043]
FIG. 3 is a view showing a first modification of the shape of the cavity 3 formed in the spacer 5.
In this modification, cavities 43, 43, 43,... Having a parallelogram cross section are formed on the outer peripheral side of the spacer 5, and cavities 42, 42, 42 having a parallelogram cross section on the inner peripheral side. 42, ... are formed.
In this modification, when the rotor lower portion 29 breaks and collides with the inner peripheral surface of the spacer 5, the spacer 5 absorbs the force and torque received from the rotor lower portion 29 as follows.
[0044]
First, the hollow portion 43 formed on the inner peripheral portion side is crushed and deformed to absorb a part of the radial force and torque.
Subsequently, the cavity 42 is crushed and deformed, and further absorbs the radial force and torque received from the rotor lower portion 29.
As described above, in the first modification, the inner cavity portion 43, 43, 43,... And the outer cavity portion 42, 42, 42,. Since the force and torque are alleviated, a higher buffering effect can be obtained.
[0045]
FIG. 4 is a view showing a second modification of the shape of the cavity 3 formed in the spacer 5. In the first modification, the hollow portions 43, 43, 43,... And the hollow portions 42, 42, 42,.
Even if the hollow portions 43, 43, 43,... And the hollow portions 42, 42, 42,... Are arranged in such a positional relationship, the same effect as in the first modification can be obtained.
[0046]
As described above, in the first and second modified examples, the hollow portions 43, 43, 43,... And the hollow portions 42, 42, 42,. Instead, the hollow portions 43, 43, 43,... Or the hollow portions 42, 42, 42,... May be filled with an impact absorbing material such as rubber or urethane.
In the first and second modified examples, the hollow portions 43, 43, 43,... And the hollow portions 42, 42, 42,. Instead, for example, the hollow portions 43, 43, 43,... May be made larger or smaller than the hollow portions 42, 42, 42,.
Moreover, you may make the space | interval of cavity part 43,43,43, ... wider or narrower than the space | interval of cavity part 42,42,42, ....
[0047]
FIG. 5 is a view showing a third modification of the shape of the cavity 3 formed in the spacer 5.
In this modification, cavities 45, 45, 45,... Having an elliptical cross-sectional shape are formed in the spacer 5 in the circumferential direction.
The major axis direction of the hollow portions 45, 45, 45,... Is inclined in the rotational direction of the rotor lower portion 29 when viewed from the outer peripheral side of the spacer 5 to the inner peripheral side.
Since the hollow portions 41, 42, and 43 have a parallelogram shape in cross section, when these hollow portions are crushed, the vicinity of each vertex of the parallelogram is crushed while being deformed. That is, the force (stress) that deforms the parallelogram is concentrated near each vertex of the parallelogram.
[0048]
On the other hand, in the third modification, when the radial force and torque are received from the rotor lower portion 29, the cross-sectional shape of the cavities 45, 45, 45,. All of the hollow portions 45, 45, 45,...
That is, in the case of the cavities 41, 42, and 43, energy is absorbed in the vicinity of the apex of the parallelogram, whereas in the cavities 45, 45, 45,. Absorbs.
For this reason, the spacer 5 can absorb larger energy, and can more effectively absorb the torque of the rotor 24 (including the rotor lower portion 29) and the centrifugal force of the rotor lower portion 29.
[0049]
As described above, in the third modified example, the inside of the cavity portions 45, 45, 45,... Is a cavity, but the present invention is not limited to this, and the cavity portions 45, 45, 45,. The inside may be filled with a shock absorber such as rubber or urethane.
[0050]
FIG. 6 is a view showing a fourth modification of the shape of the cavity 3 formed in the spacer 5.
In the fourth modification, cavities 48, 48, 48,... In which the spacer 5 is rounded at each vertex of the parallelogram cross section of the cavity 41 of the buffer part 4 of the first embodiment are provided. Is formed.
In the spacer 5 according to the fourth modification, an intermediate effect between the first embodiment and the third modification can be obtained.
That is, when the cavities 48, 48, 48,... Are deformed, the stress acts on the rounded portion of each vertex of the parallelogram, so that the stress is greater than that of the cavity 41 of the first embodiment. Concentration is relaxed.
[0051]
  As described above, in the fourth modified example, the cavity portion48, 48, 48,... Are hollow, but are not limited to this.48, 48, 48,... May be filled with an impact absorbing material such as rubber or urethane.
[0052]
  FIG. 7 is a view showing a fifth modification of the cavity 3 formed in the spacer 5.
  First5In this modification, the spacer 5 includes an inner circumferential member 52 disposed on the inner circumferential surface, an outer circumferential member 51 disposed on the outer circumferential surface, and a joining member 53 that joins the inner circumferential member 52 and the outer circumferential member 51. Has been.
  The inner peripheral member 52 is disposed concentrically on the inner side and the outer peripheral member 51 is concentrically disposed on the outer side, and the joining member 53 is fitted into grooves formed on the outer peripheral surface of the inner peripheral member 52 and the inner peripheral surface of the outer peripheral member 51. Is fixed.
  The inner circumferential member 52, the outer circumferential member 51, and the joining member 53 can be formed of other materials such as metals such as stainless steel, iron, and aluminum, or resins. These three types of members may all be made of the same material, or may be made of different materials.
[0053]
The joining member 53 is inclined in the rotational direction of the rotor lower part 29 when viewed from the outer peripheral member 51 to the inner peripheral member 52, and is formed from the outer peripheral member 51, the inner peripheral member 52, the joining members 53, 53, 53,. The cross-sectional shape of the hollow portions 54, 54, 54,... Is a substantially parallelogram.
In the fifth modification, by changing the thickness and material of the joining member 53, it is possible to adjust the degree of relaxation of the radial force and torque received from the rotor lower portion 29 when the rotor lower portion 29 breaks, and so on. Thus, the optimum thickness and material can be selected.
[0054]
  Usually, the force and torque of the rotor lower portion 29 to be absorbed by the spacer 5 differ depending on the type of the turbo molecular pump. Therefore, the material of the spacer 5 and the size of the cavity formed in the spacer 5 must be set to be optimal. Don't be. In this respect,5This modification can be dealt with by changing the material and thickness of the joining member 53.
  As described above, in the fifth modified example, the inside of the cavity portions 54, 54, 54,... Is a cavity, but the present invention is not limited to this, and the inside of the cavity portions 54, 54, 54,. For example, an impact absorbing material such as rubber or urethane may be filled.
[0055]
As described above, in the first embodiment, the following effects can be obtained.
When the rotor lower portion 29 is broken while the turbo molecular pump 1 is in operation, the spacer 5 can absorb the force from the portion of the rotor lower portion 29 that has collided.
Further, when the rotor lower part 29 breaks and the rotor 24 stops, the rotor 24 exerts torque on the fixed part of the turbo molecular pump 1, but the cavity 3 of the spacer 5 is smoothly deformed in the rotation direction of the rotor 24. Therefore, the rotor 24 is braked more gently than in the case where there is no cavity 3. Therefore, the force which the part which has fixed the turbo-molecular pump 1 and the member joined has received is reduced.
Therefore, it is possible to prevent the bolt that fixes the turbo molecular pump 1 from yielding or breaking. Further, no great force is applied to the pipes connected to the intake port and the exhaust port, and the safety of the apparatus is improved.
Further, by changing the cross section of the spacer 5 variously as in the first to fourth modifications, the optimum one is selected from the viewpoint of the braking ability when the rotor 24 is broken and the manufacturing cost. be able to.
Further, in the fifth modification, the extent to which the spacer 5 absorbs the radial force and torque can be easily adjusted by changing the size and material of the joining member 53.
[0056]
In the above embodiment, the base 27 and the casing 16 are closely arranged on the outer peripheral portion of the spacer 5, but the present invention is not limited to this, for example, between the spacer 5, the base 27, and the casing 16. May be filled with a shock absorber such as rubber or urethane.
In the above embodiment, the hollow portion has a parallelogram shape or an elliptical shape, but the hollow portion may have a honeycomb structure (honeycomb structure).
[0057]
Further, in the present embodiment, the cavity 3 is formed inside the spacer 5, but the present invention is not limited to this. For example, the cavity 41 is in close contact with the outer periphery of the spacer 5, and the cavity 41, 41, 41, It is also possible to arrange a cylindrical member provided with.
In this case, an impact absorbing material such as rubber or urethane can be disposed between the cylindrical member and the spacer 5.
[0058]
(Second Embodiment)
FIG. 8 is a view showing a turbo molecular pump 61 according to the second embodiment.
The turbo molecular pump 61 is the same as the turbo molecular pump 1 except for the spacer 65 and the cylindrical member 64. The same parts are denoted by the same reference numerals.
FIG. 9 is a view showing the spacer 65 and the cylindrical member 57 of the turbo molecular pump 61 of FIG. 8 as viewed in the XX direction of FIG.
The thread groove portion of the spacer 65 and the rotor lower portion 29 are not drawn.
[0059]
  Projections 57, 57, 57,... Are formed on the outer peripheral surface of the spacer 65. The protrusions 57, 57, 57,... Are located at the root in the rotational direction of the rotor lower part 29 rather than the tip., SuThe inner surface of the pacer 65 is inclined opposite to the rotation direction of the rotor lower portion 29. In addition, the surface with respect to the cylindrical member 64 is curved in a convex shape to have a substantially arc shape.
  The cylindrical member 64 is a member whose inner peripheral surface is processed into a cylindrical shape, and the cylindrical member 64 and the spacer 65 are disposed concentrically.
[0060]
The protrusion 57 may be formed integrally with the spacer 65, or may be attached to the spacer 65 after being formed of the same material as the spacer 65 or a different material. The cylindrical member 64 can be formed of a metal such as stainless steel, iron, or aluminum, a resin, or other materials.
A space is formed between the cylindrical member 64 and the spacer 65, and the upper end surface thereof is closed to prevent the exhaust gas from flowing therethrough.
[0061]
  The spacer 65 and the cylindrical member 64 operate as follows.
  When the rotor lower portion 29 (not shown) breaks, the rotor lower portion 29 spreads in the radial direction and collides with the spacer 65.
  At this time, the spacer 65 is arranged in the radial direction from the rotor lower portion 29 as in the first embodiment.Power ofAnd receives torque in the rotational direction of the rotor 24.
[0062]
  The spacer 65 spreads in the radial direction while rotating in the rotation direction of the rotor 24 by the radial force and torque received from the rotor lower portion 29. When the tips of the protrusions 57, 57, 57,... Are in contact with the inner peripheral surface of the cylindrical member 64, the protrusions 57, 57, 57,.Protrusion57, 57, 57,... At this time,Protrusion57 absorb the radial force and torque received from the rotor lower portion 29, and the rotor 24 is stopped.
  In this way, when the rotor lower portion 29 breaks and the rotor 24 stops, the torque received by the joint with the outside of the turbo molecular pump 61 is relaxed.
[0063]
FIG. 10 is a diagram showing a modification of the second embodiment.
In this modification, protrusions 58, 58, 58,... Are formed on the inner peripheral surface of the cylindrical member 66. The outer peripheral surface of the spacer 67 is cylindrical.
The protrusions 58, 58, 58,... Are inclined in the rotational direction of the rotor 24 from the root to the tip.
[0064]
The spacer 67, the cylindrical member 66, and the protrusions 58, 58, 58,... Configured as described above operate as follows.
When the rotor lower part 29 (not shown) breaks, it spreads in the radial direction by centrifugal force and collides with the inner peripheral surface of the spacer 67.
At this time, the spacer 67 receives a radial force from the rotor lower portion 29 and a torque in the rotational direction of the rotor 24.
[0065]
  The spacer 67 expands in the radial direction while rotating in the rotation direction of the rotor 24 by centrifugal force and torque received from the rotor lower portion 29. When the tips of the protrusions 58, 58, 58,.58, 58, 58,... Are held by the cylindrical member 66, and thus deformed by the reaction from the outer peripheral surface of the spacer 67, the58, 58, 58, ... falls in the direction of inclination. At this time, the protrusion58, 58, 58,... Absorb the centrifugal force and torque received from the rotor lower portion 29, and the rotor 24 is stopped.
  In this way, the force received by the turbo molecular pump 61 when the rotor 24 stops is alleviated.
[0066]
In the present embodiment, the following effects can be obtained.
When the rotor lower portion 29 is broken while the turbo molecular pump 61 is in operation, the spacer 65 and the cylindrical member 64 or the spacer 67 and the cylindrical member 66 can absorb the force from the contacted portion of the rotor lower portion 29.
In addition, when the rotor lower part 29 is broken and the rotor 24 stops, the rotor 24 exerts torque on the fixed part of the turbo molecular pump 1, but the spacers 65 and 67 gently brake the rotor 24. 61 The force applied to the bolts and the connected pipes is reduced.
Further, since the spacer 67 deformed by the collision with the rotor lower portion 29 directly contacts the protrusions 57 and 58, the braking characteristic of the rotor 24 different from that of the first embodiment is shown. Therefore, the selection range for the user to select the buffer mechanism is widened.
[0067]
In this embodiment and the modification, the space between the spacer 67 and the cylindrical member 64 and the space between the spacer 67 and the cylindrical member 65 are hollow, but the present invention is not limited to this. For example, rubber, urethane, etc. The impact absorbing material may be filled.
Further, an elastic member such as rubber or a plastic member made of resin or the like may be disposed between the cylindrical members 64 and 66 and the base 27 and the casing 16.
In the present embodiment, the turbo molecular pump 61 including the turbo molecular pump part and the thread groove type pump part is used as an example of the molecular pump, but the present invention is not limited to this. For example, a thread groove type pump or the like is used. You may comprise.
[0068]
  (Third embodiment)
  Furthermore, some turbo molecular pumps include a thread groove type pump portion in the base portion 73 like the turbo molecular pump 70 as schematically shown in FIG.
  The arrangement of the buffer mechanism in this case will be described.
  Casing 77InThe stator blade 72 is disposed on the rotor 76 and the rotor blade 71 is disposed on the rotor 76. A substantially lower half of the turbo molecular pump 70 is formed by a base 73, a spacer 74 that is a threaded spacer, a rotor lower portion 75, and the like. Further, a motor unit that rotates the rotor 76, a bearing that supports the rotor 76, and the like are not shown.
  Further, the thread groove may be formed in the rotor lower portion 75 instead of the spacer 74.
[0069]
The upper portion of the spacer 74 is closed by a closing member 69 so that the exhaust gas does not flow.
A cavity 78 is formed in the spacer 74. The cross-sectional shape of the cavity portion 78 is the same as that in FIGS. 2 to 6 of the first embodiment. The inside of the cavity 78 may be filled with an impact absorbing material such as rubber or urethane.
[0070]
FIG. 12 is a diagram showing a first modification. In addition, the same number is attached | subjected to the part corresponding to FIG. In the first modification, a buffer member 79 is disposed between the base 73 and the spacer 74. The buffer member 79 is a cylindrical member formed of a metal such as stainless steel. A cavity 80 is formed in the buffer member 79, and the upper end of the cavity 80 is closed by a closing member 77. The shape of the cavity 80 is the same as that in FIGS. 2 to 6 of the first embodiment. The cavity 80 may be filled with an impact absorbing material such as rubber or urethane.
[0071]
FIG. 13 is a diagram showing a second modification. In this modification, a cavity 81 is formed in the base 73. The impact caused by the collision of the rotor lower portion 75 is absorbed by the cavity 81 through the spacer 74. The shape of the cavity 81 is the same as that of FIGS. The cavity 81 may be filled with an impact absorbing material such as rubber or urethane.
[0072]
FIG. 14 is a diagram showing a third modification.
The inner peripheral member 83 and the outer peripheral member 82 constitute the structure shown in FIG. 7 of the first embodiment by the coupling member 84. The cavity formed by these members may be filled with an impact absorbing material such as rubber or urethane.
[0073]
As described above, in the third embodiment, when the thread groove type pump is formed in the base portion, the cavity portion that absorbs energy when the rotor lower portion 75 is broken is formed around the spacer 74. Can do.
[0074]
【The invention's effect】
According to the present invention, even when the rotor is broken during operation, the torque generated in the casing is reduced, the molecular pump is quickly stopped, and the molecular pump having less influence on the member connected to the molecular pump is obtained. Can be provided.
[Brief description of the drawings]
FIG. 1 is a view showing a turbo molecular pump according to a first embodiment.
FIG. 2 is a view showing a cross section of a spacer as viewed in the XX direction of FIG. 1;
FIG. 3 is a diagram showing a first modification of a spacer.
FIG. 4 is a view showing a second modification of the spacer.
FIG. 5 is a view showing a third modification of the spacer.
FIG. 6 is a view showing a fourth modification of the spacer.
FIG. 7 is a view showing a fifth modification of the spacer.
FIG. 8 is a view showing a turbo molecular pump according to a second embodiment.
FIG. 9 is a cross-sectional view of a spacer and the like according to a second embodiment.
FIG. 10 is a diagram showing a modification of the second embodiment.
FIG. 11 is a diagram schematically showing a turbo molecular pump according to a third embodiment.
FIG. 12 is a diagram showing a first modification of the third embodiment.
FIG. 13 is a diagram showing a second modification example of the third embodiment.
FIG. 14 is a diagram showing a third modification of the third embodiment.
[Explanation of symbols]
1 Turbo molecular pump
3 Cavity
5 Spacer
6 Inlet
7 Thread groove
8 Magnetic bearing
9 Radial sensor
10 Motor part
11 Rotor shaft
12 Magnetic bearing
13 Radial sensor
14 Electromagnet
15 Electromagnet
16 Casing
17 Thrust sensor
18 Water-cooled tubes
19 Exhaust port
20 Magnetic bearing
21 Rotor wing
22 Stator blade
23 Spacer
24 Rotor
25 volts
26 Metal disc
27 base
28 coils
29 Lower part of rotor
31 Radial sensor target
32 Electromagnetic target
33 Electromagnet Target
34 Radial sensor target
38 Outer periphery
39 Inner circumference
40 The part between the cavities
41 Cavity
42 Cavity
43 Cavity
45 Cavity
48 Cavity
51 Peripheral member
52 Inner peripheral member
53 Joining members
57 projection
58 projection
61 Turbo molecular pump
65 Spacer
64 Cylindrical member
66 Cylindrical member
67 Spacer
69 Closure member
70 turbo molecular pump
71 rotor wing
72 Stator blade
73 base
74 Spacer
75 Lower rotor
76 rotor
77 casing
78 Cavity
79 Buffer member
80 cavity
81 Cavity
82 Peripheral member
83 Inner circumference member
84 Cavity

Claims (7)

An exterior body in which an intake port is formed on one end side and an exhaust port is formed on the other end side;
A rotor rotatably supported inside the exterior body;
A motor for rotating the rotor;
A stator disposed around the rotor and having a cavity formed therein having a cross-sectional shape inclined at a predetermined angle with respect to a radial direction of the rotor;
A molecular pump characterized by comprising: An exterior body in which an intake port is formed on one end side and an exhaust port is formed on the other end side;
A rotor that is rotatably supported inside the exterior body;
A motor for rotating the rotor;
A stator disposed around the rotor;
A cushioning member disposed on the outer periphery of the stator, and having a hollow portion having a cross-sectional shape inclined at a predetermined angle with respect to a radial direction of the rotor;
A molecular pump characterized by comprising:   The predetermined cross-sectional shape is a substantially parallelogram, and one of two opposing sides is substantially parallel to a tangent in the rotational direction of the rotor, and the rotor is within the one set of sides. 3. The molecular pump according to claim 1, wherein a side closer to is located in a rotation direction of the rotor than a side farther from the rotor.   The predetermined cross-sectional shape is a substantially ellipse, and of the two intersections of the major axis of the substantially ellipse and the substantially ellipse, the intersection closer to the rotor is closer to the rotor than the intersection farther from the rotor. The molecular pump according to claim 1, wherein the molecular pump is located in a rotational direction. An exterior body in which an intake port is formed on one end side and an exhaust port is formed on the other end side;
A rotor that is rotatably supported inside the exterior body;
A motor for rotating the rotor;
A stator disposed around the rotor;
A cylindrical member having a substantially cylindrical inner peripheral surface disposed on the outer peripheral portion of the stator with a predetermined gap therebetween,
In a cavity formed between the stator and the cylindrical member, at least one of the outer peripheral portion of the stator or the inner peripheral portion of the cylindrical member has a protrusion inclined at a predetermined angle with the radial direction of the rotor. A molecular pump characterized by   The molecular pump according to any one of claims 1 to 5, wherein the hollow portion is formed in an axial direction of the rotor, and at least one end thereof is closed.   The molecular pump according to any one of claims 1 to 6, wherein the cavity is filled with a shock absorbing material.

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