JP2021173257A - Turbomolecular pump and stator of turbomolecular pump - Google Patents

Abstract

To provide a turbomolecular pump capable of suppressing deterioration in an exhaust performance due to backflow of gas molecules.SOLUTION: A turbomolecular pump comprises: multi-stage rotor blades in which a plurality of blades is formed, and which are provided in a pump axial direction; and multi-stage stator blades 30 which are alternately arranged in the pump axial direction with respect to the multi-stage rotor blades, and provided with a plurality of blades 301. The stator blade 30 of each stage is composed of a plurality of divided stator blades 30a and 30b. In an opposite part of the plurality of divided stator blades 30a, 30b, a gap 305 is formed. The stator blades 30 of the respective stages adjacent to each other in the pump axial direction are out of a phase with each other in a circumferential direction of the gap 305.SELECTED DRAWING: Figure 3

Description

The present invention relates to a turbo molecular pump.

The turbo molecular pump exhausts gas molecules flowing in from the intake port of the pump by rotating the multi-stage rotor blades on which the turbine blades are formed at high speed with respect to the multi-stage stator blades on which the turbine blades are formed. Exhaust to the mouth. Due to assembly restrictions, the stator blades of each stage are composed of a set of two split stator blades divided into a semicircular shape (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-370808

The stator blades are assembled so as to be sandwiched by a pair of upper and lower spacer rings, but at that time, since the pair of split stator blades are arranged so as not to overlap each other, there is a slight gap between the split stator blades. It will occur. This gap allows the backflow of gas molecules from the exhaust side to the intake side, which is one of the causes of deterioration of exhaust performance.

In the turbo molecular pump according to the embodiment of the present invention, a plurality of blades are formed, and a plurality of stages of rotor blades provided in the pump axial direction and a plurality of stages of the turbo molecular pump are alternately arranged in the pump axial direction with respect to the plurality of stages of the rotor blades. A plurality of stages of stator blades provided with blades of the above are provided, and the stator blades of each stage are composed of a plurality of divided stator blades, and a gap is formed in an opposing portion of the plurality of divided stator blades. , The stator blades of the respective stages adjacent to each other in the pump axial direction are out of phase with each other in the circumferential direction of the gap.

According to the present invention, it is possible to suppress deterioration of exhaust performance due to backflow of gas molecules.

FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a turbo molecular pump. FIG. 2 is a plan view of the Nth stage stator blade. FIG. 3 is a diagram showing the N-th stage and N + 1-stage stator blades. FIG. 4 is a diagram illustrating the effect on reflux molecules. FIG. 5 is a diagram showing a comparative example in which the assembly phases are the same. FIG. 6 is a diagram showing an example of the assembly phase of the plurality of stator blades. FIG. 7 is a diagram showing another example of the assembly phase of the plurality of stator blades. FIG. 8 is a diagram illustrating a positioning mechanism. FIG. 9 is a diagram showing a CC cross section of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a turbo molecular pump 1. In the present embodiment, a magnetic bearing type turbo molecular pump will be described as an example, but the present invention is not limited to the magnetic bearing type and can be applied to various turbo molecular pumps.

The turbo molecular pump 1 includes a turbo pump stage TP composed of a plurality of stages of stator blades 30 and a plurality of stages of rotor blades 40, and a drag pump stage DP composed of a stator cylindrical portion 31 and a rotor cylindrical portion 41. Have. In the example shown in FIG. 1, the turbopump stage TP is composed of an 8-stage stator blade 30 and a 9-stage rotor blade 40, but the number of each stage is not limited to this. In the drag pump stage DP, a screw groove is formed in the stator cylindrical portion 31 or the rotor cylindrical portion 41. The rotor blade 40 and the rotor cylindrical portion 41 are formed on the pump rotor 4a. The pump rotor 4a is fastened to the shaft 4b, which is a rotor shaft, by a plurality of bolts 50. The rotating body 4 is formed by fastening the pump rotor 4a and the shaft 4b with bolts 50 and integrating them.

Each of the plurality of stages of the stator blades 30 is composed of a pair of split stator blades (reference numerals 30a and 30b in FIG. 2) having a half-split shape. The multi-stage stator blades 30 are alternately arranged with respect to the plurality of stages of rotor blades 40 provided in the axial direction of the pump rotor 4a. Each stator blade 30 is laminated in the pump axial direction via a plurality of spacer rings 33. The shaft 4b is magnetically levitated and supported by magnetic bearings 34, 35, 36 provided on the base 3. Although detailed illustration is omitted, each magnetic bearing 34 to 36 includes an electromagnet and a displacement sensor. The floating position of the shaft 4b is detected by the displacement sensor.

The rotating body 4 in which the pump rotor 4a and the shaft 4b are bolted together is rotationally driven by the motor 10. When the magnetic bearings are not operating, the shaft 4b is supported by emergency mechanical bearings 37a, 37b. When the rotating body 4 is rotated at high speed by the motor 10, the gas on the pump intake port side is sequentially exhausted by the turbo pump stage TP and the drag pump stage DP, and is discharged from the exhaust port 38. An auxiliary pump is connected to the exhaust port 38.

2 and 3 are views for explaining the stator blade 30. FIG. 2 is a plan view of the stator blade 30 of the Nth stage from the pump intake port side (intake side) of the eight stages. FIG. 3 is a plan view of the N-th stage and N + 1-stage stator blades 30. As shown in FIG. 2, the stator blade 30 is composed of a set of two divided stator blades 30a and 30b divided into a semicircular shape due to assembly restrictions. The divided stator blades 30a and 30b divided into a semicircular shape are arranged in a circular shape with a gap 305. Each of the divided stator blades 30a and 30b has a plurality of blades 301 formed radially, an arc-shaped inner rib 302 provided on the inner peripheral side of the blade 301, and an arc-shaped inner rib 302 provided on the outer peripheral side of the blade 301. It is provided with an outer rib 303. In the example shown in FIG. 2, both the inner ribs 302 and the outer ribs 303 are provided on the split stator blades 30a and 30b, but one of them may be provided.

When assembling the plurality of stages of the stator blades 30 as shown in FIG. 1, a pair of split stator blades 30a and 30b are placed on the spacer ring 33, and the split stator blades 30a and 30b are placed on the outer ribs 303. The spacer ring 33 on the upper side (intake side) is placed on the upper side (intake side). The split stator blades 30a and 30b are supported so that the outer ribs 303 are sandwiched by a pair of upper and lower spacer rings. The split stator blades 30a and 30b are required to be assembled so that both ends in the circumferential direction do not overlap with each other. Therefore, as shown in FIG. 2, the stator blades 30 are assembled with a gap 305 formed between the split stator blades 30a and 30b.

FIG. 3 is a diagram for explaining the assembly phase of the plurality of stages of the stator blades 30, and is a plan view of the Nth and N + 1th stages of the stator blades 30 (divided stator blades 30a and 30b) as viewed from the intake side. The assembly phase of the stator blades 30 in the embodiment is an index indicating how to assemble the pair of split stator blades 30a and 30b in the stator blades 30, and specifically, the rotation of the gap 305 from the reference position. The angle. In the example shown in FIG. 3, the position of the gap 305 of the N + 1th stage stator blade 30 is shifted counterclockwise by the rotation angle (+ θ) with respect to the position of the gap 305 of the Nth stage stator blade 30. (Hereafter, the phase shift in the counterclockwise direction is positive). That is, the assembly phase of the N + 1th stage stator blade 30 with respect to the Nth stage stator blade 30 is + θ.

FIG. 4 shows a cross section taken along the line AA of FIG. 2, and when a pair of adjacent stator blades 30 (Nth stage and N + 1th stage) are assembled and shifted by the phase = + θ as shown in FIG. It is a figure explaining the effect on the backflow molecule. As will be described later, in FIGS. 3 and 4, the assembly phase = + θ is set to be about twice the 1-pitch angle θ1 of the rotor blade 40 in the N + 1 stage.

As shown in FIG. 3, since the phase of the N-stage stator blade 30 and the N + 1-stage stator blade 30 are shifted by + θ, the gap 305 between the split stator blade 30a and the split stator blade 30b is 305. It is displaced in the circumferential direction (left-right direction in FIG. 4). The gap 305 of the N + 1th stage stator blade 30 is shifted to the right in FIG. 4 with respect to the gap 305 of the Nth stage stator blade 30.

As shown in FIG. 4, consider a case where the gas molecules G on the exhaust side flow back through the gap 305 of the stator blade 30 in the N + 1 stage. The movement direction distribution of the gas molecules G that have passed through the gap 305 of the stator blade 30 is biased in the pump axial direction. Therefore, most of the gas molecules G that have passed through the gap 305 of the stator blade 30 in the N + 1th stage proceed upward in the drawing along the pump shaft. The gas molecule G traveling upward in the drawing may collide with the blade 401 of the rotating rotor blade 40, or may pass between the blade 401 and the blade 401 to reach the Nth stage stator blade 30. ..

In the example shown in FIG. 4, since the assembly phases of the N-th stage and N + 1-stage stator blades 30 are shifted by + θ, the gap 305 between the N-stage stator blades 30 and the gap between the N + 1-stage stator blades 30 It does not face the 305. Therefore, the gas molecules G that have reached the Nth stage stator blade 30 collide with the blade 301, and the backflow to the intake side is prevented. The gas molecules G that collide with the blade 301 are exhausted to the exhaust side by the exhaust action of the turbo pump stage TP including the stator blades 30 and the rotor blades 40.

In this way, by shifting the gap 305 of the N-th stage stator blade 30 and the gap 305 of the N + 1-stage stator blade 30 by the phase + θ, the gas molecule G that flows back through the gap 305 of the N + 1-stage stator blade 30. Most of the above will be blocked from moving to the intake side by the N-stage stator blade 30. As a result, deterioration of exhaust performance due to backflow of gas molecules G can be suppressed. The effect of suppressing such a decrease in exhaust performance is more remarkable when the gas flow rate is large.

FIG. 5 is a diagram showing a case where the phases of the gaps 305 match as a comparative example. In this case, the gas molecules G that have passed through the gap 305 of the N + 1th stage stator blade 30 in the axial direction tend to flow back to the intake side through the gap 305 of the Nth stage stator blade 30. That is, when the assembly phases θ of the adjacent stator blades 30 are aligned in each stage (θ = 0), the influence of the backflow becomes large and the exhaust property deteriorates.

The above-mentioned backflow suppression effect can be obtained regardless of how the stator blades 30 in the adjacent stages are out of phase with each other. In the example shown in FIG. 4, the size of the assembly phase θ (= + θ) is set to be about twice the one pitch angle θ1 of the rotor blade 40 of the N + 1 stage, but the size of the assembly phase θ is set. Is preferably set larger than the 1-pitch angle θ1 of the rotor blade 40 of the N + 1th stage. When the magnitude of the assembly phase θ is smaller than the 1-pitch angle θ1 of the rotor blade 40 of the N + 1 stage, the gas molecule G that has passed between the blades 401 passes through the gap 305 of the stator blade 30 of the N stage. The probability of backflow to the exhaust side increases.

With respect to the plurality of stages of the stator blades 30, backflow of gas molecules can be suppressed if the phases of the stator blades 30 adjacent to each other in the upper and lower stages are out of phase. For example, as a method of shifting the adjacent stator blades 30 by the phase θ, either of FIGS. 6 and 7 may be used. In the example shown in FIG. 6, the assembly phases of the N + 1 to N + 3rd stage stator blades 30 are in order counterclockwise + θ, + 2θ, and + 3θ with respect to the Nth stage stator blade 30, and each stage is left. The phase is shifted by + θ in the clockwise direction. On the other hand, in the example shown in FIG. 7, the Nth stage and the N + 2nd stage have the same phase (θ = 0), and the assembly phases of the N + 1th stage and the N + 3rd stage are set to + θ. In either case, the same suppressing effect on the deterioration of exhaust performance can be obtained. Further, when the phase of the adjacent stator blades 30 is set to θ = 90 degrees (deg), that is, when θ = 90 deg is set in FIG. 7, the arrangement is excellent in assembly workability.

(Positioning mechanism)
When the stator blades 30 in a plurality of stages are shifted by a constant phase θ as shown in FIGS. 6 and 7, if a positioning mechanism as shown in FIGS. 8 and 9 is provided, workability is improved and assembly errors can be prevented. Can be planned. FIG. 8 shows the spacer ring 33 (33a, 33b, 33c) on which the Nth, N + 1 and N + 2nd stage stator blades 30 (divided stator blades 30a, 30b) are mounted, as viewed from the pump intake port side. It is a plan view. FIG. 9 is a cross-sectional view taken along the line CC of the alternately laminated stator blades 30 and the spacer rings 33a and 33b. In FIGS. 8 and 9, the assembly phase is set to −θ, and the split stator blades 30a and 30b are shown by alternate long and short dash lines. That is, the N + 1th stage and N + 2nd stage stator blades 30 (divided stator blades 30a and 30b) have phases of −θ and -2θ with respect to the Nth stage stator blades 30 (divided stator blades 30a and 30b), respectively. It is out of alignment.

The spacer rings 33 (33a to 33c) are provided with pins P1 and P2 for positioning the split stator blades 30a and 30b. As shown in FIG. 9, the pin P1 is provided on the intake side surface of the blade mounting portion 331 formed on the spacer ring 33, and the pin P2 is provided on the exhaust side surface of the blade mounting portion 331. .. The pins P1 and P2 are provided so as to be driven into the pin holes 332 and 333 formed in the blade mounting portion 331. The height h of the exposed portion of the pins P1 and P2 is set to be smaller than the thickness dimension of the outer rib 303 of the split stator blades 30a and 30b.

When the N + 1th stage stator blades 30 (divided stator blades 30a, 30b) are mounted on the spacer ring 33b, the split stator blades are placed on the blade mounting portion 331 on the left side of the pin P1 as shown in FIG. 30a is placed, and the split stator blade 30b is placed on the blade mounting portion 331 on the right side of the drawing of the pin P1. The assembly phase of the split stator blades 30a and 30b is set by the pin P1. Next, as shown in FIG. 9, the spacer ring 33a is placed on the outer rib 303 of the N + 1th stage stator blades 30 (divided stator blades 30a, 30b). At that time, the spacer ring 33a is placed so that the pin P2 provided on the exhaust side surface of the blade mounting portion 331 of the spacer ring 33a enters the gap 305 of the stator blade 30 in the N + 1 stage.

After that, the N-stage split stator wing 30a is mounted on the wing mounting portion 331 on the left side of the pin P1 of the spacer ring 33a, and the N-stage split stator wing 30a is mounted on the wing mounting portion 331 on the right side of the pin P1. Place 30b. As a result, the N + 1th stage stator blade 30 is assembled to the Nth stage stator blade 30 in the assembly phase (−θ). By providing the spacer rings 33 with pins P1 and P2 with a phase difference (180-θ) deg, the stator blades 30 of adjacent stages can be easily assembled with a phase difference (−θ).

It will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following embodiments.

[1] In the turbo molecular pump according to one aspect, a plurality of blades are formed, and a plurality of stages of rotor blades provided in the pump axial direction and a plurality of stages of the rotor blades are alternately arranged in the pump axial direction. , A plurality of stages of stator blades provided with a plurality of blades, the stator blades of each stage are composed of a plurality of divided stator blades, and a gap is formed in the facing portion of the plurality of divided stator blades. The stator blades of the respective stages adjacent to each other in the pump axial direction are out of phase with each other in the circumferential direction of the gap.

For example, as shown in FIG. 2, the stator blade 30 has a pair of divided stator blades 30a and 30b that are divided into a semicircular shape and arranged in a circular shape with a gap 305. The assembly phase of the N + 1th stage stator blade 30 (that is, the circumferential phase) is shifted counterclockwise by an angle (+ θ) with respect to the assembly phase of the adjacent Nth stage stator blade 30. That is, in the N-th stage and the N + 1-th stage stator blades 30, the circumferential phase of the gap 305 is deviated from each other by an angle θ. By shifting the assembly phase of the adjacent stator blades 30 in this way, the backflow of gas molecules can be suppressed, and the deterioration of the exhaust performance can be suppressed.

In the above-described embodiment, the stator blade 30 is divided into two semicircular split stator blades 30a and 30b, but it may be divided into three or more fan-shaped split stator blades. In that case, the assembled stator blade 30 will have the same number of gaps 305 as the number of divisions. Can produce the same effect as.

[2] In the turbo molecular pump according to the above [1], the rotor blades include a plurality of blades arranged at predetermined intervals in the circumferential direction, and the angles formed by adjacent blades in the circumferential direction of the rotor blades are one pitch. When the angle is set, the amount of phase shift of the circumferential phase of the stator blades of each stage adjacent to the pump axis direction is set to be larger than the one pitch angle.

For example, when the magnitude of the assembly phase θ is smaller than the 1-pitch angle θ1 of the rotor blade 40 of the N + 1 stage, the gas molecule G that has passed between the blades 401 passes through the gap 305 of the stator blade 30 of the N stage. There is a high probability that it will flow back to the exhaust side. However, by setting the assembly phase θ larger than the one pitch angle θ1 (about twice) as shown in FIG. 4A, the probability of backflow can be reduced. The effect of suppressing the deterioration of exhaust performance can be further enhanced.

[3] In the turbo molecular pump according to the above [1], the amount of phase shift of the circumferential phase of the stator blades in the adjacent stages is set to 90 deg. When laminating the stator blades 30, it is sufficient to alternately shift the stator blades 30 by 90 deg for each stage, so that the assembly workability is excellent.

[4] The turbo molecular pump according to any one of the above [1] to [3] includes a plurality of spacer rings alternately laminated with the stator blades in a plurality of stages in the pump axial direction, and the spacer rings are provided. , Has a positioning member for positioning the circumferential phase of the stator blades adjacent in the pump axial direction.

By providing the spacer rings 33 with pins P1 and P2 for positioning, when the N + 1th stage split stator blades 30a and 30b are placed on the spacer ring 33b, the split stator blades 30a and 30b are placed on both sides of the pin P1. When the spacer ring 33a is placed on the N + 1th stage split stator blades 30a and 30b, the pin P2 is inserted into the gap 305 of the Nth stage split stator blades 30a and 30b. By arranging the spacer ring 33a, the N-th stage and N + 1-th stage split stator blades 30a and 30b are automatically set to the phase shift θ. Therefore, it is excellent in assembling property and can surely prevent the occurrence of a mistake regarding the assembly phase.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

1 ... Turbo molecular pump, 4a ... Pump rotor, 4b ... Shaft, 30 ... Stator blade, 30a, 30b ... Split stator blade, 33, 30a to 30c ... Spacer ring, 40 ... Rotor blade, 301, 401 ... Blade, 305 ... Gap, P1, P2 ... Pin

The present invention relates to a turbo molecular pump and a stator of a turbo molecular pump.

In the turbo molecular pump according to the embodiment of the present invention, a plurality of blades are formed, and a plurality of stages of rotor blades provided in the pump axial direction and a plurality of stages of the turbo molecular pump are alternately arranged in the pump axial direction with respect to the plurality of stages of the rotor blades. A plurality of stages of stator blades provided with blades of the above are provided, and the stator blades of each stage are composed of a plurality of divided stator blades, and a gap is formed in an opposing portion of the plurality of divided stator blades. , The stator blades of the respective stages adjacent to each other in the pump axial direction are out of phase with each other in the circumferential direction of the gap.
The stator of the turbo molecular pump according to the aspect of the present invention is a rotor having a plurality of stages of rotor blades in which a plurality of blades are formed and provided in the pump axial direction, and a rotor having a plurality of stages of the rotor blades alternately in the pump axial direction. The stator in a turbo molecular pump including a stator having a plurality of stages of stator blades arranged and provided with a plurality of blades, wherein the stator blades in each stage are composed of a plurality of divided stator blades and the plurality of stages. A gap is formed in the facing portion of the split stator blade, and the stator blades of the respective stages adjacent to each other in the pump axial direction are out of phase with each other in the circumferential direction of the gap.

Claims (4)

Multiple blades are formed, and a multi-stage rotor blade provided in the direction of the pump axis,
A plurality of stages of stator blades, which are alternately arranged in the pump axial direction with respect to the plurality of stages of the rotor blades and are provided with a plurality of blades, are provided.
The stator blades in each stage are composed of a plurality of divided stator blades, and a gap is formed in the facing portions of the plurality of divided stator blades.
A turbo molecular pump in which the stator blades of each stage adjacent to each other in the pump axial direction are out of phase with each other in the circumferential direction of the gap. In the turbo molecular pump according to claim 1,
The rotor blades include a plurality of blades arranged at predetermined intervals in the circumferential direction.
When the angle formed by the blades adjacent to each other in the circumferential direction of the rotor blade is set to one pitch angle, the amount of phase shift of the circumferential phase of the stator blade of each stage adjacent to the pump axial direction is larger than the one pitch angle. A large turbo molecular pump. In the turbo molecular pump according to claim 1,
A turbo molecular pump in which the amount of phase shift of the circumferential phase of the stator blades in adjacent stages is set to 90 deg. The turbo molecular pump according to any one of claims 1 to 3.
It is provided with a plurality of spacer rings that are alternately laminated with the stator blades in a plurality of stages in the pump axial direction.
The spacer ring is a turbo molecular pump having a positioning member for positioning the circumferential phase of a stator blade adjacent to the pump axial direction.

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