JP3135312U - Turbo molecular pump - Google Patents

Abstract

To provide a turbo molecular pump capable of reducing the back flow of gas molecules and improving exhaust performance.
In the turbo molecular pump, the position of the divided portion 112b of one fixed blade 11b is arranged at a position different from the divided portions 112a and 112c of the fixed blades 11a and 11c located above and below. Therefore, since the flow of the gas molecule which is going to flow backward through the division part 112c of the fixed wing 11c is stopped by the fixed wing 11b, the gas molecule is prevented from flowing backward through the division part of the fixed wing as a result. be able to.
[Selection] Figure 3

Description

  The present invention relates to a turbo molecular pump used for evacuation of a semiconductor manufacturing apparatus or the like.

  The turbo-molecular pump used for high vacuum exhaust is equipped with multiple stages of rotating blades and multiple stages of fixed blades that are arranged alternately, and performs vacuum exhaust by rotating the rotor blades at high speed relative to the fixed blades. It is. Each rotor blade and fixed blade are composed of a plurality of blade portions, and the rotor blade is formed in a rotor that is rotationally driven by a motor, and the fixed blades are stacked via a spacer and fixed to the base of the pump.

  In order to facilitate the assembly of the turbo molecular pump, the stationary blades at each stage are generally divided into two semicircular divided stationary blades. (For example, see Patent Document 1)

JP 2005-337028 A

  However, since the fixed blades are arranged and assembled in an arbitrary state when viewed from the rotation axis direction of the rotor blades, the divided portions of the divided fixed blades of each stage are viewed from the rotation axis direction of the rotor blades. In such a case, when assembled so as to be arranged in a straight line, gas molecules flow backward from the divided portion, and the exhaust performance of the turbo molecular pump is lowered.

Similarly, when assembled so that the clearance between the fixed blades of each stage matches that seen from the rotation axis direction of the rotor blades, the fixed blades viewed from the rotation axis direction of the rotor blades The projected gap area is increased, gas molecules are likely to flow backward, and the exhaust performance of the turbo molecular pump is reduced.

Further, conventionally, when assembling the turbo molecular pump, the fixed blades are not arranged in consideration of the position of the split portions of the split fixed blades and the state between the blade gaps of the fixed blades. The location of the fixed wing split sections and the state between the blade gaps of the fixed wings at each stage may vary from one aircraft to the next, and turbomolecular pumps assembled in such a state will have a backflow of gas molecules for each aircraft. As a result, the exhaust performance of the turbo molecular pump varies.

Therefore, the present invention solves the above problems, suppresses the deterioration of the exhaust performance of the turbo molecular pump due to the backflow of gas molecules, and reduces the variation in the exhaust performance of the turbomolecular pump due to the difference in the backflow of gas molecules. The goal is to achieve uniform performance.

  A turbo molecular pump according to a first device is a turbo molecular pump in which a plurality of stages of rotating blades and a plurality of stages of stationary blades are alternately arranged in the rotation axis direction of the rotating blades. Consists of a pair of split fixed blades, and of the split fixed blades, the split portion of one split fixed blade is arranged at a position different from the split portions of the front and rear split fixed blades when viewed from the direction of the previous rotation axis. It is provided. This feature can reduce the backflow of gas molecules to be exhausted through the split portion of the split fixed blade.

The turbo molecular pump according to the second invention is a turbo molecular pump in which a plurality of stages of rotating blades and a plurality of stages of fixed blades are alternately arranged in the rotating shaft direction of the rotating blades. The fixed wings of the plurality of stages are arranged so as to cover the gaps between the wings of one fixed wing with the wings of the other fixed wings. With this feature, the projected gap area between the fixed blades as viewed from the rotation axis direction of the rotor blades can be reduced, and the backflow of gas molecules can be reduced.

  A turbo molecular pump according to a third aspect of the present invention is the turbo molecular pump according to the first aspect of the present invention, wherein each of the plurality of spacers on which the plurality of stages of fixed blades are mounted is provided with a split portion of the split fixed blades and the spacers. A site that uniquely defines the positional relationship is provided, and each spacer is stacked so that the site is arranged in a unique relationship. With this feature, it is possible to uniquely determine the arrangement state of a plurality of stages of fixed blades that reduce the backflow of gas molecules to be exhausted through the split portions of the split fixed blades.

  A turbo molecular pump according to a fourth aspect of the present invention is the turbo molecular pump according to the second aspect of the present invention, wherein each of the plurality of spacers on which the plurality of stages of fixed blades are mounted has a gap between the blade portions of the fixed blades and the A site that uniquely determines the positional relationship with the spacer is provided, and the spacers are stacked so that the site is arranged in a unique relationship. With this feature, it is possible to uniquely determine the arrangement state of a plurality of stages of fixed blades that reduce the projected gap area between the fixed blades as viewed from the rotation axis direction of the rotor blades.

  According to the present invention, it is possible to improve the turbo molecular pump exhaust performance such as the exhaust speed and the ultimate vacuum by reducing the back flow of gas molecules. In addition, by uniquely determining the position of each stage of the fixed wing so as to satisfy the conditions of the present invention, the variation in the exhaust performance of the turbo molecular pump due to the difference in the backflow of gas molecules is reduced. Performance can be homogenized.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an embodiment of a turbo molecular pump according to the present invention, and is a cross-sectional view of a pump body 1. The turbo molecular pump includes a pump main body 1 shown in FIG. 1 and a controller (not shown) that supplies power to the pump main body 1 to control rotational driving.

  Inside the casing 3 of the pump body 1, a rotating body composed of a rotor 20 and a shaft 7 that are bolted to each other is provided. The shaft 7 to which the rotor 20 is fixed is supported in a non-contact manner by a pair of upper and lower radial magnetic bearings 31 and 32 and a thrust magnetic bearing 33 provided on the stator column 10 a of the base 10, and is driven to rotate by the motor 6. When the pump is stopped (when magnetic levitation is stopped) or when a power failure occurs, the shaft 7 is supported by protective touch-down bearings 26 and 27.

  The rotor 20 is formed with a plurality of stages of rotating blades 21 and a rotating cylindrical portion 22. On the other hand, on the base 10 side, ring-shaped spacers 13 are stacked along the inner peripheral surface of the casing 3, and a plurality of stages of fixed blades 11 are provided so as to be sandwiched between the spacers 13. Furthermore, a fixed cylindrical portion 12 having a spiral groove formed on the inner peripheral surface is provided at the lower portion of the plurality of fixed wings 11. In the turbo molecular pump of the present embodiment, a turbine blade portion is constituted by a plurality of stages of rotating blades 21 and a plurality of stages of fixed blades 11 arranged alternately in the axial direction, and then the rotating cylinder portion 22 and the fixed cylinder. The molecular drag pump unit is configured by the unit 12. The rotating cylindrical portion 22 is provided close to the inner peripheral surface of the fixed cylindrical portion 12, and a spiral groove is formed on the inner peripheral surface of the fixed cylindrical portion 12. In the molecular drag pump unit, the exhaust function by the viscous flow is performed by the spiral groove of the fixed cylindrical unit 12 and the rotating cylindrical unit 22 rotating at high speed.

  The turbo molecular pump in which the turbine blade part and the molecular drag pump part shown in FIG. 1 are combined is called a wide area turbo molecular pump. The gas molecules flowing in from the intake port 14 are knocked down by the turbine blades and are compressed and exhausted toward the downstream side. The compressed gas molecules are further compressed by the molecular drag pump unit and discharged from the exhaust port 15.

  FIG. 2 is a view showing the structure of the fixed wing 11 shown in FIG. The fixed wing 11 is composed of two divided semi-circular divided fixed wings 110 a and 110 b, and a position where each of the divided fixed wings faces becomes a divided portion 112. Each split fixed wing includes a plurality of wing parts 113, and a gap 114 is formed between the wing parts. The split fixed blades 110a and 110b are made of a material such as stainless steel or aluminum alloy, and the blades are formed by cutting a thick plate or casting, cutting a thin plate or casting, or bending a thin plate after etching. 113 is formed.

  FIG. 3 is a view showing an arrangement state of the fixed blades 11 of the turbo molecular pump according to the first device. FIG. 3A is a view of the fixed blade viewed from the rotation axis direction of the rotary blade, and FIG. 3B is a view of the fixed blade viewed from a direction orthogonal to the rotation axis of the rotary blade. For the sake of explanation, FIG. 3 shows only a part (three stages) of the rotor blades 21 and the fixed blades 11, and the description of the rotor 13, the spacer 13 that sandwiches the fixed blades, and the like is omitted. Moreover, since the same shape is continuing about the wing | blade part and the wing | blade space | interval of the fixed wing | blade 11, only one part is described and the remaining part is abbreviate | omitted and described.

  As shown in FIG. 3 (b), in the first arrangement state of the fixed blade 11 of the turbo molecular pump according to the present invention, the fixed blades 11a and 11c are located at the upper and lower positions of the divided portion 112b of the fixed blade 11b. It is disposed at a position different from the portions 112a and 112c. Therefore, the flow of gas molecules (arrow in FIG. 3 (b)) trying to flow backward through the dividing portion 112c of the fixed wing 11c is stopped by the fixed wing 11b. Therefore, as a result, it is possible to reduce the backflow of gas molecules through the split portion of the fixed wing.

  FIG. 4 is a diagram showing an arrangement state of the fixed blades 11 of the turbo molecular pump according to the second device. FIG. 4A is a view of the fixed wing viewed from the rotation axis direction of the rotary wing, and FIG. 4B is a view of the fixed wing viewed from a direction orthogonal to the rotation axis of the rotary wing. For the sake of explanation, FIG. 4 also shows only a part (three stages) of the rotary blade 21 and the fixed blade 11, and the description of the spacer 13 and the like that sandwich the rotor 20 and the fixed blade is omitted. Moreover, since the same shape is continuing about the wing | blade part and the wing | blade space | interval of the fixed wing | blade 11, only one part is described and the remaining part is abbreviate | omitted and described.

As shown in FIG. 4, in the second arrangement state of the stationary blade 11 of the turbo molecular pump according to the present invention, the stationary blade 11c has a clearance 114c above it when viewed from the rotational axis direction of the rotating blade. The wings 11a and 11b are disposed so as to be covered with the wing parts 113a and 113b. The flow of gas molecules (arrow in FIG. 4 (b)) trying to flow backward through the gap 114c of the fixed wing 11c is stopped by the wing portions 113a and 113b of the fixed wings 11a and 11b. Therefore, as a result, it is possible to reduce the backflow of gas molecules through the gap between the wing portions of the fixed wing.

  Next, an example of a method for arranging the fixed blades when assembling the turbo molecular pump according to the present invention will be described below. In the turbo molecular pump 1 according to the present invention, a rotating part composed of a shaft 7, a rotor 20, a rotating blade 21 and a rotating cylindrical part 22 is attached to a base 10, and then a spacer 13 is placed on the lower side (exhaust port 15 side). And the fixed blades 11 are arranged between the spacers and are sandwiched between the spacers 13. At the time of this assembly, in order to arrange the fixed wings in the state of the first device or the second device, the divided portions of the divided fixed wings 110a and 110b that form the fixed wings 11 on the spacers 13 holding the fixed wings. 112 or a portion that uniquely determines the positional relationship between the position of the gap 114 between the blade portions of the fixed blade 11 and the spacer 13 is provided, and the spacers are stacked using the portion as a mark.

FIG. 5 is a view showing the structure of the spacer 13 shown in FIG. The spacer 13 is formed with stepped portions 130a and 130b (130b does not appear on the drawing) at both ends of the circumferential portion thereof, and the spacers stacked in the vertical direction are engaged by engaging the stepped portions. Fixed. In addition, the thickness h1 of the spacer is not the same for all the spacers 13, but varies depending on the arrangement interval of the fixed blades. Further, as shown in FIG. 6, protrusions 131a and 131b are provided at two upper ends (A part) of the circumferential part of the spacer 13. As shown in FIG.

FIG. 7 is a diagram in which the fixed wing 11 is placed on the spacer 13. As shown in FIG. 7, spacer protrusions 131a and 131b are placed in contact with the tips of the wings of the split fixed wings 110a and 110b, so that the split parts of the split fixed wings or the wings of the fixed wings are placed. The positional relationship between the position of the gap and the spacer can be uniquely determined.

Therefore, when the fixed blades are arranged between the rotor blades, this projection is used as a mark, so that when the turbo molecular pump is assembled, the divided portion of one of the divided fixed blades is viewed from the previous rotation axis direction. When installing, it is arranged at a position different from the divided parts of the divided fixed wings before and after that, or the gap between the wing parts of one fixed wing is covered with the wing parts of the other fixed wings. It can be done easily.

In addition, when the split part of one split fixed wing is viewed from the direction of the rotation axis in the previous period, it is arranged at a position different from the split part of the split fixed wings before and after that, or between the wing parts of one fixed wing The positional relationship of the projections of each spacer that satisfies the condition that the gap is disposed so as to be covered with the blades of other fixed blades is uniquely determined, and according to the positional relationship, the spacers are stacked and the turbo molecular pump is installed. By assembling, the positions of the fixed wings of each stage disposed between the wings of the rotary wings can be determined at predetermined positions.

As a specific arrangement method when the divided portion of one divided fixed blade is disposed at a position different from the divided portions of the front and rear divided fixed blades when viewed from the direction of the rotation axis in the previous period, the lowermost stage ( In the case of stacking sequentially from the stationary blades at the location closest to the exhaust port 15, there is a method in which the positions of the divided portions when viewed from the rotating shaft direction of the rotating blades are different by 90 degrees. As another arrangement method, when the number of stages of the fixed blades is N (N is an integer), the rotating blades are sequentially stacked from the bottom fixed blade (the place closest to the exhaust port 15). There is an arrangement method in which the positions of the divided portions are different by “360 / N” degrees when viewed from the direction of the rotation axis.

Next, as an example of a specific arrangement method when the gap between the wings of one fixed wing is covered with the wings of another fixed wing when viewed from the direction of the rotation axis in the previous period In the case where the number of fixed blades is N (N is an integer) and the number of blades of each fixed blade is M (M is an integer), the lowermost (the place closest to the exhaust port 15) When sequentially laminating from the fixed blades, there is a method of disposing the fixed blades so that the phases of the fixed blades are different by “360 / (M × N)” degrees when viewed from the rotation axis direction of the rotary blades. In addition, when the width of the blade portion when the fixed blade is viewed from the rotation axis direction of the rotor blade is wider than the clearance between the blades of the fixed blade, the rotation shaft of the rotor blade is You may arrange | position so that the phase of a fixed wing | blade when it sees from a direction may differ by "180 / M" degree | times.

In addition, when the split part of one split fixed wing is viewed from the direction of the rotation axis in the previous period, the split part of the split fixed wing before and after the split part is at a different position, and the gap between the wing parts of the single fixed wing, By arranging the fixed wings at each stage so as to cover the wings of other fixed wings, the backflow of gas molecules can be further reduced.

In addition, the part which determines uniquely the positional relationship of the division part of the division | segmentation fixed wing | blade provided in the spacer 13 or the space | interval of the clearance gap between the wing | blade part of a fixed wing | blade, and a spacer is not limited to the structure of protrusion 131a, 131b of FIG. That is, as an alternative to the protrusion, a hole is formed in the surface of the spacer 13 where the fixed wing is placed, and a positioning pin is inserted, or a split portion of the split fixed wing or a wing portion of the fixed wing on the side surface of the spacer 13 It may be configured to provide a marking line that uniquely determines the positional relationship between the position of the gap and the spacer,

The above-described embodiments are merely examples of the present invention, and it is obvious that appropriate changes and modifications can be made within the scope of the present invention.

It is sectional drawing which shows one Embodiment of the turbo-molecular pump which concerns on this invention. It is a figure which shows the structure of the fixed wing | blade 11 of the turbo-molecular pump based on this invention. It is a figure which shows the 1st arrangement | positioning state of the fixed wing | blade 11 of the turbo-molecular pump which concerns on this invention. It is a figure which shows the 2nd arrangement | positioning state of the fixed wing | blade 11 of the turbo-molecular pump based on this invention. It is a figure which shows the structure of the spacer 13 of the turbo-molecular pump based on this invention. It is an enlarged view of the projection part of FIG. FIG. 6 is a view in which protrusions 131a and 131b of the spacer 13 are placed in contact with the tips of the blade portions of the split fixed blades 110a and 110b.

Explanation of symbols

  1: pump body, 10: base, 11: fixed blade, 12: fixed cylindrical portion, 13: spacer, 20: rotor, 21: rotating blade, 22: rotating cylindrical portion, 110a, 110b: split fixed blade, 112, 112a , 112b, 112c: division part, 113, 113a, 113b, 113c: blade part, 114, 114a, 114b, 114c: gap between blades, 130a, 130b: stepped part 131a, 131b: projection part

Claims (4)

In a turbo molecular pump in which a plurality of stages of rotating blades and a plurality of stages of fixed blades are alternately arranged in the rotation axis direction of the rotating blades,
Each of the plurality of stages of fixed wings comprises a pair of split fixed wings,
Among the divided fixed wings, the divided portion of one divided fixed wing is disposed at a position different from the divided portions of the divided fixed wings before and after the divided fixed wing when viewed from the rotation axis direction in the previous period. Turbo molecular pump. In a turbo molecular pump in which a plurality of stages of rotating blades and a plurality of stages of fixed blades are alternately arranged in the rotation axis direction of the rotating blades,
When viewed from the rotation axis direction in the previous period, among the plurality of stages of fixed blades, the gap between the blade portions of one fixed blade is disposed so as to be covered with the blade portions of the other fixed blades Turbo molecular pump.   Each of the plurality of spacers on which the plurality of stages of fixed wings are mounted is provided with a portion that uniquely determines the positional relationship between the divided portions of the divided fixed wings and the spacer, and the portions are arranged in a unique relationship. The turbo molecular pump according to claim 1, wherein each spacer is stacked on the turbo molecular pump. Each of the plurality of spacers on which the plurality of stages of fixed blades are mounted is provided with a portion that uniquely determines the positional relationship between the gap between the blade portions of the fixed blade and the spacer, and the portions are arranged in a unique relationship. The turbo molecular pump according to claim 2, wherein each spacer is stacked as described above.

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