JP2011033027A - Turbo molecular pump rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid risks that a rotor body is destroyed and energy accumulated therein is rapidly discharged to a housing, so-called an explosion. <P>SOLUTION: A shaft supports a first rotor structure 101, and the first rotor structure includes a rotor blade ring 119 and a blade 123. Moreover, the first rotor structure 101 supports a rotor sleeve 124 and includes a recess 130. The recess 130 extends in an axial direction and a radial direction to form a hollow space. A size of a fragment is reduced and a destruction process is extended while including the recess extending in the axial direction and existing at a radial direction inside, namely the recess extending in the radial direction from a symmetric rotation axis line so as to from the hollow space. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a turbomolecular pump rotor according to the superordinate concept of claim 1.

In the prior art, during the last decade, a few minor principles have been formed on which the turbomolecular pump rotor is constructed.
A commonly used first construction type is to provide disks with a set of turbo blades and to shrink or clamp these disks on a shaft. Such a structure is shown in European Patent Publication No. 1559914. In a turbomolecular pump with a large pumping speed and with five rows of active magnetic bearings, this will in fact form a large structural length.

  Another popular form of construction provides a shorter structure by surrounding the central shaft with the required drive and bearing components by the rotor body, in which case the shaft and rotor body are They are connected to each other on the front side. For example, as shown in German Patent Publication No. 1728487, the rotor body may be formed from a plurality of disks. However, as shown in FIG. 1 of European Patent Publication No. 1517042, it is common practice to provide the rotor body as an integral part. Although this structure is certainly preferable with respect to the structure length, other troubles such as the following burst troubles may occur. The rotational speed of the turbo molecular pump is in the range of tens of thousands of rpm. A pumping speed of several hundred liters / second is advantageous in this type of rotor body, but in the case of a large pump having such a pumping speed, the rotational energy accumulated therein actually reaches a very high value. There are things to do. When a so-called rupture occurs in which the rotor body breaks and the energy stored therein is suddenly released to the housing, the released energy places an excessive load on the joint between the housing and the container to be evacuated. As a result, the danger to the surroundings cannot be completely eliminated.

European Patent Publication No. 1559914 German Patent Publication No. 1728487 European Patent Publication No. 1517042

  The object of the present invention is therefore to provide a turbomolecular pump rotor in which the above mentioned dangers are avoided in particular.

  This problem is solved by a turbomolecular pump rotor having the features of claim 1, a turbomolecular pump according to claim 6 and a rotor structure according to claim 8. Claims 2-5 and 7 provide advantageous variants of the invention.

  Since the turbomolecular pump rotor according to claim 1 does not show a rotor body which is generally used, safety in the case of rupture is improved. This reduces the size of the debris and prolongs the destruction process. This prevents excessive loads on the joint between the turbo pump housing and the container to be evacuated. The first rotor portion including the first pump structure and the second pump structure can be manufactured from a flat material that provides higher strength within a given cost range. This further improves safety.

  This configuration further comprises the first rotor part having a recess extending axially and radially inward, i.e. a recess extending radially from the symmetrical axis of rotation so that a hollow space is formed. It can be improved. It is then advantageous to be able to arrange other components such as labyrinth seals or bearings and parts of the drive in this hollow space. Thereby, the structure length is shortened.

  Another modification is intended to form the third pump structure as a rotor disk with vanes. This, on the one hand, improves safety because such individual discs do not exhibit dangerous behavior in bursting, on the other hand, the disc structure allows a greater degree of freedom in terms of blade configuration even in the high vacuum range. To. Within the high vacuum range, the blades are formed at a steep angle with respect to the direction of motion and extend long in the axial and tangential directions. If multiple blade rows are arranged on one common body for this pressure range, this configuration is limited for manufacturing methods such as milling and sawing. In this way, better vacuum data is achieved since this limitation does not apply to the disc.

  In another variant, it is proposed to provide a reinforcement ring between the support rings, since the bursting behavior is further improved by placing the reinforcement ring between the support rings with vanes.

  Yet another modification proposes that the turbomolecular pump rotor has a second rotor portion with at least two pump structures. This achieves an improved burst behavior over the prior art and further reduces the number of parts used. In this case, the cost is reduced by reducing the size of the material portion.

  The examples illustrate the invention and its modifications in detail and explore its advantages.

FIG. 1 shows a cross-sectional view of a turbomolecular pump rotor according to a first embodiment and a driving device region of the turbomolecular pump. FIG. 2 is a cross-sectional view of the turbo molecular pump rotor and the turbo molecular pump drive unit region and the bearing region according to the second embodiment. FIG. 3 shows a cross-sectional view of a turbomolecular pump rotor according to a third embodiment. FIG. 4 shows a cross-sectional view of a turbomolecular pump rotor according to a fourth embodiment. FIG. 5 shows a cross-sectional view of a turbomolecular pump rotor according to a fifth embodiment.

A first embodiment of a turbomolecular pump rotor is shown in cross-section along the axis of rotation in FIG.
FIG. 1 initially shows a portion 160 of a turbomolecular vacuum pump housing, which is hereinafter referred to as a turbo pump. This part receives the motor coil 161, which generates a rotating magnetic field. The rotating magnetic field cooperates with the motor magnet 162 to rotate the turbo molecular pump rotor at a high speed. The motor magnet is covered by a sleeve 163 and is disposed on the shaft 132 of the turbomolecular pump rotor protected from the negative effects of the acting centrifugal force. The shaft has a recess on its front side, preferably towards the high vacuum side, in which at least one permanent magnetic ring 190 is arranged, the permanent magnetic ring being unlubricated for supporting the turbomolecular pump rotor The rotor side portion of the magnetic bearing is formed.

  The turbo pump has a pump stator, and the pump stator includes stator disks 112, 116, 120 and 124 provided with vanes as a stator side pump structure, and the stator disk includes spacer rings 113, 117, 121 and 125 are spaced apart from each other in the axial direction. The pump stator further includes a Holweck stator 128 as another stator side pump structure.

  The turbo-molecular pump rotor includes rotor blade rings 111, 115, 119 and 123 and a rotor sleeve 127 as a rotor side pump structure. Each rotor blade ring is formed by a blade that extends radially outward in the rotor and lies in one of the planes 150, 151, 152 and 153 for each of the rotor blade rings. The fixed plane of the rotor sleeve forms a plane 154. The planes 150, 151, 152, 153 and 154 are axially spaced from each other.

  Pump structures 111 and 112 cooperate to form a first pump stage 110, which is located on the suction side and operates in the high vacuum range. Pump structures 115 and 116, 119 and 120, and 123 and 124 form other pump stages 114, 118, and 122 for the medium pressure range, and rotor sleeve 127 and Holbeck stator 128 together form a Holbeck stage 126.

  The shaft supports the first rotor structure part 101, which comprises the blades of the rotor blade rings 119 and 123, which are advantageously an integral part of the first rotor structure part. . The first rotor structure further supports a rotor sleeve 127, the rotor sleeve comprising a carbon fiber composite material. The first rotor portion has a recess 130. The recess extends in the axial direction and the radial direction to form a hollow space. Within this hollow space the parts of the housing 160 and the motor coil 161 enter, whereby a short structural length of the turbo pump is achieved. Another advantage is obtained by adapting the rotor disk ring to a pressure range that exists between the pressure range for the Holbeck pump stage and the pressure range for the high vacuum pump stage. Within this pressure range the blade angle is flat, i.e. the blade is only slightly inclined with respect to the rotor disk ring plane. Due to the smaller radial depth of the blades than in the high vacuum range, this makes it possible to form grooves in a cost-effective manner by sawing into the cylindrical blank body.

  The shaft supports a first support ring 108 and a second support ring 109 on the side of the first rotor structure that faces high vacuum. The first support ring supports the pump structure of the first pump stage 110 formed as a rotor blade ring, and the first pump stage is designed for the high vacuum pressure range. The second support ring supports the pump structure of the second pump stage 114 formed as a rotor blade ring. Within the pressure range of both pump stages, the vane angle is steeper, i.e. the vanes are tilted more strongly with respect to the rotor vane ring plane than at pump stages 118 and 122. Therefore, the manufacture of the disk having the support ring and the rotor blade ring is advantageous in terms of cost, and is hardly limited by the manufacturing method. This limitation lies in the fact that in a multi-row structure, the processing tool must be considered in machining from one row of blades to another.

  The structural scheme with the first rotor structural part and the first and second support rings itself provides a great advantage for the bursting behavior. This is, on the one hand, that the size of the largest piece in this construction system is clearly smaller compared to a fully integrated bell. On the other hand, if the initial price is the same, a higher-grade, particularly high-strength material can be used for the rotor structure. In particular, since the crack formed in one structural part only occurs up to the boundary with the next structural part, the time course of the rupture works favorably. As a result, even when the stored energy is the same, a time extension that reduces the generated force can be obtained.

The rupture behavior can be further improved by placing a reinforcing ring between the first and second support rings and between the second support ring and the first rotor structural part.
An inner hole 172 for the counterweight 173 is advantageously arranged between the rotor blade rings 119 and 123. Along with the inner bore 170 and the counterweight 171 in the front side of the shaft, the rotor can be balanced using an easily accessible weight.

  The first rotor portion may each have more than two rotor vane rings, depending on the demand for turbo pump vacuum data, and more or less support rings than shown. May be.

A second embodiment of a turbomolecular pump rotor is shown in cross-section along the axis of rotation in FIG.
This example relates to a turbomolecular pump with an active magnetic bearing. A restraint bearing 295, a radial bearing coil 291, a radial sensor 293 and a motor coil 261 are disposed in the housing portion 260 so as to surround the shaft 232. The motor coil cooperates with a motor magnet 262 that is on the shaft and protected by a sleeve 263, so that when the motor coil is energized, the shaft is rotated at high speed. The radial sensor cooperates with the axial radial sensor target 294 to allow the determination of the radial deflection of the rotor and thus the operation of the radial bearing coil by means of a magnetic bearing control electronics not shown. To do. The radial bearing coil, in cooperation with the radial bearing target 292 on the shaft side, enables the radial positioning of the shaft, that is, the radial positioning of the degree of deviation from the central axis by energizing the radial bearing coil. The restraint bearing avoids contact between the housing and the shaft when the displacement is large.

  As a stationary pump structure, the turbo molecular pump of this example has a holbeck stator 228 on the pre-vacuum (back pressure) side, and a spiral groove extends in the holbeck stator, and the spiral groove is disposed on the rotor. Together with the sleeve 227, the Holbeck stage 226 is formed.

  Another stationary pump structure is the stator disks 212, 216, 220 and 224 with vane rings, which are axially driven by spacer rings 213, 217, 221 and 225 disposed therebetween. Is spaced. Pump structures formed as rotor blade rings 211, 215, 219 and 223 enter the intermediate space between the stator and the disk. The stationary pump structure and the rotor side pump structure cooperate in a pair. The rotor blade ring 211, together with the stator disk 212, forms a first pump stage 210 that is directed towards the chamber and operates in a high vacuum. Similarly, the stator disk 216 and rotor blade ring 215 form a second pump stage 214 that follows, the stator disk 220 and rotor blade ring 219 form a third pump stage 218, and finally the stator disk. 224 and rotor blade ring 223 form a fourth pump stage 222 that operates at the transition pressure to the Holbeck stage. The rotor blade rings are each disposed in planes 250, 251, 252 and 253 that are axially spaced from one another, and the fixed area of the rotor sleeve forms a plane 254.

  A rotor-side pump structure in the form of rotor blade rings 219 and 223 is disposed on the first rotor portion 201 and forms an integral body with the first rotor portion. A rotor sleeve 227 is coupled to the first rotor portion. The first rotor portion has a recess 230 in the center thereof. Advantageously, this hollow space extending axially and radially from the center receives at least a part of the constraining bearing, thereby reducing the structural length of the turbo pump. The hollow space may be enlarged so that a housing portion 260 containing radial bearings, radial sensors and motor coils has a portion of its axial extension present therein. This further reduces the structural length of the turbo pump that extends in the direction of the rotor symmetry axis.

  The first rotor portion is coupled to the front side of the shaft 232 using fixing means such as screws 280. The shaft has a recess, and the recess and the insertion portion 289 of the first rotor portion engage, thereby simplifying radial positioning.

  As shown in this example, the first rotor portion has a support portion 201a. The support portion extends from the first rotor portion in the direction of high vacuum in the axial direction, that is, in the direction opposite to the shaft. A support ring 208 is disposed on the support portion, and the support ring and the rotor blade ring 211 are coupled. The other support ring 209 and the rotor blade ring 215 are similarly coupled to each other. The support ring with the rotor blade ring is preferably manufacturable from solid material, for example by sawing. For this reason, it is advantageous in terms of cost that a material having high strength can be used. The separation between the first rotor part and the support ring improves the safety of the rupture by the destruction of the structural part being delayed in this separation. Furthermore, the maximum size of the debris is reduced. Since the support portion 201a ensures a reliable and continuous centering of the support ring, an unbalance change due to the loss of the centering can be avoided.

  In one variation, a reinforcing ring 281 is provided, which is arranged to contact both support rings 208 and 209 on their surfaces and prevent radial expansion of the support ring due to centrifugal forces. .

  In another modification, a counter bore 270 is provided on the front side of the support portion 201a, and the counterweight 271 is designed to be inserted into the counter bore. A very good balance of the rotor is achieved by the easy access to the balance bore, together with the lower balance bore 272 provided between the rotor blade rings 219 and 223 and the balance weight 273 present therein if necessary. .

  The first rotor portion may each have more than two rotor vane rings, depending on the demand for turbo pump vacuum data, and more or fewer support rings than shown. Also good.

  A third embodiment of a turbomolecular pump rotor is shown in cross-sectional view along the axis of rotation in FIG. This is an alternative structure for the turbomolecular pump rotor, and other components of the turbo pump are not shown.

  The turbomolecular pump rotor includes a shaft 332, and the front side of the shaft and the first rotor portion 301 are coupled. The shaft has a recess, and the recess and the insertion portion 389 of the first rotor part are engaged, whereby radial centering is performed. A portion of the length of the shaft exists in the hollow space 330, and the hollow space extends axially from the rotor axis of the first rotor portion over a portion of the radius. This hollow space accepts some of the other components of the turbo pump, such as the bearings and the drive, thereby reducing the structural length of the turbo pump. The first rotor portion has three rotor blade rings 319, 323 and 329, which are arranged in three planes 352, 353 and 354.

  There is a second rotor portion 302 opposite the axis of the first rotor portion. The second rotor part is centered relative to the first rotor part by centering means 382. As shown in this example, the centering means is formed as a recess in the first rotor portion, and the recess and the second rotor portion are engaged. The second rotor portion has a high vacuum side recess 383 opposite to the first rotor portion, and a screw 380 is disposed in the recess, the screw comprising the shaft, the first rotor portion and the second rotor portion. The rotor part is fixedly connected. The second rotor portion includes rotor blade rings 311 and 315, which are disposed in planes 350 and 351. This structure also gives favorable behavior in the event of a burst based on the size of the corresponding debris. The advantage of this arrangement is that the number of structural parts is small, so only a few parts are combined. At the same time, the material is advantageous over the case of a solid bell or an individual basic body including all rotor blade rings.

The number of rotor blade rings arranged in each of the rotor parts is greater than or equal to two, depending on the turbo pump vacuum technology design.
A fourth embodiment of a turbomolecular pump rotor is shown in cross-sectional view along the axis of rotation in FIG. This is an alternative structure for the turbomolecular pump rotor, and other components of the turbo pump are not shown.

  In addition to a first rotor portion 401 that includes rotor blade portions 419, 423, and 429 disposed in axially spaced planes 452, 453, and 454, the turbomolecular pump rotor includes a protrusion 402a. The second rotor portion 402 is provided. Support rings 408 and 409 are disposed on the protrusions and are positioned by, for example, shrink fitting or clamping. The rotor blade ring 415 on the plane 451 is formed integrally with the support ring 409. The rotor blade ring 411 existing in the plane 450 is formed integrally with the support ring 408. The protrusion 402a surrounds the high vacuum side recess 483, and a screw 480 is disposed in the recess. A screw couples the first rotor portion 401, the second rotor portion 402 and the shaft 432 together. The first rotor part has a recess 430 on its side facing the axis, which provides space for stator side components such as bearings and motors. This recess reduces the structural length of the turbo pump. It is quite clear that the structure consisting of two parts and a support ring improves the behavior in the event of a rupture. Advantageously, there is a centering means that ensures a reliable centering of the first and second rotor parts as in the third example. The structure shown in this fourth example provides a great degree of freedom in the selection of the blade shape of the rotor blade rings 411 and 415 due to the configuration with the support ring. Furthermore, a good centering of the support ring is achieved, so that the balance properties are improved. The shaft and the first rotor portion are centered with each other by a plug 489 that engages a recess on the front side of the shaft.

  The first rotor portion may each have more than two rotor blade rings, depending on the demand for turbo pump vacuum data, and more or less blade rings than shown. Also good.

  A fifth embodiment of a turbomolecular pump rotor is shown in cross-sectional view along the axis of rotation in FIG. This is an alternative structure for the turbomolecular pump rotor, and other components of the turbo pump are not shown.

  The turbomolecular pump rotor shown in partial cross-section has rotor blade rings 511, 515 and 519, which are arranged in axially spaced planes 550, 551 and 552. And it is a part of the first rotor portion 501. Each rotor blade ring has blades as in the above example, and the blades are formed so as to extend in the radial direction and resist the direction of movement. The first rotor portion is coupled to the front side of shaft 532 by screws 580. The shaft and the first rotor are centered with each other by the insertion portion 589, and the insertion portion is engaged with a recess on the front side of the shaft. The pre-vacuum (back pressure) side front side 586 of the first rotor portion and the second rotor portion 502 are coupled. This connection is ensured by suitable fixing means, for example a connection screw 585. Centering of the first and second rotor parts is achieved by a protrusion 597 that is coupled to the recess of the first rotor part and is present on the front side of the second rotor part. Dynamic characteristics must be taken into account in the form of the centering means. When the rotor rotates at high speed, the centrifugal force acts to expand in the region of coupling of the first and second rotor parts. This should not result in lost alignment. This is ensured in an advantageous manner by the reinforcing ring 581. Since the reinforcing ring is arranged in the recess, it is advantageous not to affect the gap between the rotor and the stator. The second rotor portion includes a pump structure in the form of a rotor vane ring 523 and a Holbeck sleeve 584 disposed in axially spaced planes 553 and 554. The first rotor portion has a recess 530 that, together with the central through hole 588 of the second rotor portion, provides a large hollow space for receiving the turbo pump bearing and motor structure portions. The turbomolecular pump rotor in this example has the great advantage of a very safe bursting behavior and a shortened structural length, because this rotor also produces only small fragments in the event of a burst. Because it does. The number of rotor blade rings in the second rotor portion may be greater, and the Holbeck sleeve may be omitted, if desired. This depends on the desired vacuum data.

101, 201, 301, 401, 501 First rotor portion 108, 109, 208, 209, 408, 409 Support ring 110, 114, 118, 122, 210, 214, 218, 222 Pump stage 111, 115, 119, 123, 211, 215, 219, 223, 311, 315, 319, 323, 329, 411, 415, 419, 423, 429, 511, 515, 519, 523 Rotor blade ring 112, 116, 120, 124, 212, 216, 220, 224 Stator disk 113, 117, 121, 125, 213, 217, 221, 225 Spacer ring 126, 226 Holbeck stage 127, 227 Rotor sleeve 128, 228 Holbeck stator 130, 230, 330, 383 43 , 483,530 recess (hollow space)
132, 232, 332, 432, 532 shaft 150-154, 250-254, 350-354, 450-454, 550-554 plane 160, 260 housing part 161, 261 motor coil 162, 262 motor magnet 163, 263 sleeve 170, 172, 270, 272 Inner holes 171, 173, 271, 273 Counterweight 190 Permanent magnetic ring 201a Support part 280, 380, 480, 580, 585 Screw 281, 581 Reinforcement ring 289, 389, 489, 589 Insertion part 291 Radial bearing coil 292 Radial bearing target 293 Radial sensor 294 Radial sensor target 295 Restraint bearing 302, 402, 502 Second rotor portion 382 Centering means 402a Protruding portion 584 Holbe Sleeve 586 Pre-vacuum (back pressure) side front side 587 Protrusion 588 Through hole

Claims (8)

A turbomolecular pump rotor with a first pump structure (119; 219; 319; 419; 519) and a second pump structure (123; 223; 323; 423; 523), wherein each pump In a turbomolecular pump rotor, the structure is preferably provided to form a pump stage with a stator side pump structure (120, 124; 220, 224; 320, 324; 420, 424; 520, 524),
The first rotor portion (101; 201; 301; 401; 501) includes a first pump structure and a second pump structure (123; 223; 323; 423; 523), and the turbomolecular pump rotor is the first A turbo-molecular pump rotor having three pump structures (111, 115; 211, 215; 311, 411, 415; 511, 515, 519). The first rotor part (101; 201; 301; 401; 501) has a recess (130; 230; 330; 430; 530) that is radially inward and extends in the axial direction. The turbo-molecular pump rotor according to claim 1. 3. The turbomolecular pump rotor according to claim 1, wherein the third pump structure includes vanes disposed on a support ring (108, 109; 208, 209; 408, 409). The turbomolecular pump rotor includes two support rings (108, 109; 208, 209; 408, 409) with vanes disposed thereon, and a reinforcing ring (281) is provided between the support rings. The turbomolecular pump rotor according to claim 3, wherein The turbo-molecular pump rotor is provided with two pump structures (311, 315; 411, 415; 511, 515, 519) suitably provided to form a pump stage together with the respective stator side pump structures. The turbomolecular pump rotor according to claim 1, comprising two rotor parts (302; 402; 502). A turbomolecular pump comprising the turbomolecular pump rotor according to any one of claims 1 to 5. The turbomolecular pump according to claim 6, characterized in that the turbomolecular pump comprises an active radial magnetic bearing (291, 292, 293, 294) and an active axial magnetic bearing. The rotor structure has at least two pump structures (119, 123; 219, 223; 319, 323; 419, 423; 515, 519) and one recess (130; 230; 330; 430; 530); And a rotor structure part for a turbomolecular pump rotor, characterized in that it is adapted to be coupled to a rotor structure part (108, 109; 208, 209; 302; 402; 502) comprising other pump structures.

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