Vacuum pump

Abstract

To provide a vacuum pump having a structure capable of securing specified positioning accuracy of spacers even when dimensional tolerance in manufacturing is loosened to some extent, and reducing manufacturing costs of the vacuum pump, a cylindrical portion used in the vacuum pump, and a base portion.SOLUTION: A vacuum pump 10 including a gas transferring mechanism 40 having rotary blades 26 and fixed blades 38 alternately arranged in an axial direction in multiple stages in a casing 11, includes a plurality of annular spacers 39 stacked to position the fixed blades 38 in an axial direction M, a casing 11 having a cylindrical portion 11A disposed while surrounding an outer periphery of the plurality of stacked spacers 39, and a base 11B mounted at a lower portion of the cylindrical portion 11A, and an upper radial positioning portion 20 and a lower radial positioning portion 21 respectively disposed at upper and lower two positions in the cylindrical portion 11A and coaxially holding at least the spacer 39 of the uppermost stage and the spacer of the lowermost stage of the stacked spacers 39.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vacuum pump, a cylindrical portion used in the vacuum pump, and a base portion, and particularly to a vacuum pump used in a semiconductor manufacturing apparatus, an analysis apparatus, etc., a cylindrical portion used in the vacuum pump, and a base portion.

Background Art

[0002] In the manufacture of semiconductor devices such as memories and integrated circuits, processes such as film formation and etching of insulating films, metal films, semiconductor films, etc. are carried out in a process chamber in a high-vacuum state in order to avoid the influence of dust in the air. For the exhaust in the process chamber, a vacuum pump such as a turbomolecular pump is used, for example.

[0003] As such a vacuum pump, a vacuum pump provided with a gas transfer mechanism (turbomolecular mechanism) having rotating blades and stationary blades arranged in multiple stages alternately in the axial direction in a casing having an intake port for sucking gas from the outside and an exhaust port for exhausting the sucked gas to the outside is known (see, for example, Patent Document 1).

[0004] Figs. 7 to 9 are diagrams for explaining the schematic structure of a conventional vacuum pump provided with a gas transfer mechanism in which rotating blades and stationary blades are arranged in multiple stages alternately in the axial direction in a casing. Fig. 7 is a vertical sectional view of the vacuum pump, Fig. 8 is an enlarged view of part H in Fig. 7, and Fig. 9 is a sectional view for explaining an annular spacer for positioning the stationary blades at a predetermined interval in the vertical direction in the casing.

[0005] First, in the conventional vacuum pump 100 shown in Figs. 7 and 8, a casing 101 forming the exterior of the vacuum pump 100 forms the housing of the vacuum pump 100 together with a cylindrical portion 102 and a base 103 provided at the lower part of the cylindrical portion 102. Inside the casing 101, a gas transfer mechanism 104, which is a structure that enables the vacuum pump 100 to perform an exhaust function, is housed.

[0006] This gas transfer mechanism 104 is broadly composed of a rotating part (rotor part) 105 that is rotatably supported and a fixed part (stator part) 106 that is fixed to the casing 101.

[0007] The rotating section 105 of the gas transfer mechanism 104 includes a shaft 107 which is the axis of rotation, a rotor 108 disposed on the shaft 107, and a plurality of rotating blades 109 provided on the rotor 108.

[0008] A motor section 110 is provided in the middle of the shaft 107 in the axial direction and is enclosed within the stator column 111. Furthermore, within the stator column 111, radial magnetic bearing devices 114 and 115 are provided on the intake port 112 side and the exhaust port 113 side of the shaft 107, respectively, to support the shaft 107 radially (radially) without contact with the motor section 110. In addition, an axial magnetic bearing device 116 is provided at the lower end of the shaft 107 to support the shaft 107 axially (axially) without contact.

[0009] The fixed portion 106 of the gas transfer mechanism 104 is formed on the inner circumference side of the casing 101. This fixed portion 106 is equipped with a cylindrical spacer 117 and a plurality of fixed vanes 118 whose axial spacing is maintained by the spacer 117. The fixed vanes 118 are disc-shaped plate members that extend radially perpendicular to the axis O2 of the shaft 107.

[0010] The spacer 117 is a substantially cylindrical fixing member that extends along the axial direction of the casing 101 and comprises a first radial support portion 117a that circumferentially faces the outer circumferential surface of the fixed blade 118 and abuts against the inner circumferential surface of the cylindrical portion 102, and a second radial support portion 117b that circumferentially faces the outer circumferential surface of the rotor blade 109 and abuts against the inner circumferential surface of the first radial support portion 117a.

[0011] The assembly of the fixed blades 118 and spacers 117 of the vacuum pump 100 is carried out by first fixing the rotating part 105 onto the base 103, then placing the lowest fixed blade 118 on the base 103, and then stacking the spacers 117 and fixed blades 118 alternately in order. In this stacking, the spacers 117 are stacked with the fixed blades 118 housed on the inner circumferential surface of the first radial support part 117a, and the inner circumferential surface of the first radial support part 117a is fitted and connected to the outer circumferential surface of the small diameter part 117c which forms a stepped portion on the back surface (outer circumferential surface) of the second radial support part 117b. At the same time, the rotating blades 109 are interposed between the fixed blades 118, and by repeating this process, a gas transfer mechanism 104 having a rotating part 105 with rotating blades 109 and fixed blades 118 arranged alternately in multiple stages in the axial direction and a cylindrical fixed part 106 is assembled and formed.

[0012] After the assembly of the fixed part 106, the casing 101 is placed over the rotating part 105 and the fixed part 106 from above, on the side of the uppermost spacer 117. This houses the gas transfer mechanism 104 inside the casing 101. Furthermore, the casing 101 housing the gas transfer mechanism 104 has a positioning part 102a formed in a stepped shape on a part of the upper inner circumferential surface of the cylindrical part 102, which abuts against the upper surface and outer circumferential surface of the uppermost spacer 117, thereby positioning the casing 101 and the gas transfer mechanism 104 in the axial direction M and in the width direction (thrust direction) R.

[0013] Meanwhile, the lower part of the casing 101 is in contact with the inner surface of the cylindrical portion 102 and the outer surface of the base 103, with a gap S1 between them, and an O-ring 119 for sealing, which is disposed in an annular groove 103a formed on the outer circumference of the base 103, sandwiched in between. After that, when the gap between the cylindrical portion 102 and the base 103 is fixed with bolts 120, the casing 101 and the gas transfer mechanism 104 are integrated.

[0014] By the way, in the structure of the fixed section 106, which is made up of multiple stages by stacking spacers 117 and fixed blades 118 in order, as shown in Figures 7 and 8 of the vacuum pump 100, if the machining accuracy of the various dimensions A, B, and C of the spacer 117 shown in Figure 9 is not high, when stacked, the tilt of the gas transfer mechanism 104 with respect to the axis O2, that is, the movement in the radial direction R (deviation from coaxiality), will increase as you move upwards. Therefore, during machining, the accuracy of each of dimensions A, B, and C must be high (strict). Here, dimension A is the inner circumference dimension of the first radial support section 114a, dimension B is the outer circumference dimension of the spacer 117, and dimension C is the outer circumference dimension of the small diameter section (step section) 114c. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] Japanese Patent Publication No. 2008-66327 [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] As described above, in the vacuum pump 100 shown in Figures 7 and 8, the cylindrical portion 102 of the casing 101 has a positioning portion 102a for positioning the fixed portion 106 of the gas transfer mechanism 104 housed in the cylindrical portion 102, located only at the top. Therefore, as the number of stacked spacers 117 increases, the radial movement R (deviation in coaxiality) on the fixed portion 106 side increases in proportion to the number of layers, making it difficult to attach the casing 101 to the fixed portion 106. Consequently, stricter dimensional tolerances are required during the processing of the spacers 117, resulting in difficult processing and high manufacturing costs.

[0017] Therefore, a technical challenge arises in providing a vacuum pump with a structure that can ensure a certain positioning accuracy of the spacer even with loose dimensional tolerances during manufacturing, and that can also reduce the manufacturing cost of the vacuum pump, as well as a cylindrical part and base used in this vacuum pump. The present invention aims to solve this challenge. [Means for solving the problem]

[0018] The present invention was proposed to achieve the above objective, and the invention described in claim 1 provides a vacuum pump comprising a turbo molecular mechanism having rotating blades and stationary blades arranged alternately in multiple stages in the axial direction within a casing having an intake port for drawing in gas from the outside and an exhaust port for exhausting the drawn-in gas to the outside, the casing comprising a plurality of annular spacers stacked to position the stationary blades in the axial direction, a cylindrical portion arranged to surround at least the outer circumference of the stacked plurality of spacers and a base portion attached to the lower part of the cylindrical portion, and radial positioning portions provided at two positions, upper and lower, within the cylindrical portion, respectively, which coaxially hold at least the uppermost spacer and the lowermost spacer of the stacked plurality of spacers.

[0019] In this configuration, when a cylindrical section of the casing is placed over a multi-stage arrangement of spacers with alternating fixed and rotary blades, the uppermost spacer on the intake side and the lowermost spacer on the exhaust side are both positioned axially and radially (thrust direction) by the positioning section within the cylindrical section. In other words, by positioning the two upper and lower spacers in the multi-stage arrangement, the entire multi-stage arrangement of spacers is prevented from moving or tilting radially. As a result, even if the machining accuracy (tolerance) during the manufacturing of the casing and spacers is somewhat loosened, a certain positioning accuracy can be ensured by suppressing (reducing) radial movement and tilting, thus simplifying the manufacturing of the casing and spacers and lowering manufacturing costs.

[0020] The invention described in claim 2 provides a vacuum pump in which, in the configuration described in claim 1, the radial positioning portion on the upper side of the inner circumferential surface of the cylindrical portion is provided corresponding to the outer circumferential surfaces of the plurality of spacers, and the radial positioning portion on the lower side of the cylindrical portion is provided corresponding to the side surface of the base portion.

[0021] In this configuration, when a cylindrical section of the casing is placed over a multi-stage arrangement of spacers, which are arranged by alternately stacking fixed and rotary blades, the upper positioning section inside the cylindrical section, located on the upper intake side, positions the multi-stage arrangement of spacers in the axial and radial directions. On the other hand, the spacer on the lower exhaust side is positioned in the axial and radial directions together with the base by the lower positioning section inside the cylindrical section contacting the side surface of the base. Therefore, in this case as well, the positioning of the two upper and lower spacers in the axial and radial directions suppresses (reduces) radial movement or tilting of the entire multi-stage arrangement of spacers. As a result, even if the machining accuracy (tolerance) during the manufacturing of the casing and spacers is somewhat loosened, a certain positioning accuracy can be ensured, simplifying the production of the casing and spacers and reducing manufacturing costs.

[0022] The invention described in claim 3 provides a vacuum pump in which, in the configuration described in claim 2, the upper radial positioning portion is provided corresponding to the outer circumferential surface of the uppermost spacer.

[0023] In this configuration, when a casing is placed over a multi-stage arrangement of fixed and rotary blades stacked alternately, the uppermost spacer on the intake side and the lower spacer on the exhaust side are both positioned axially and radially by an upper radial positioning section provided inside the casing. This makes it possible to further loosen the machining accuracy (tolerance) during the manufacturing of the casing and spacers.

[0024] The invention described in claim 4 provides a vacuum pump in which, in the configuration described in claim 1 or 2, the plurality of spacers comprises a radial support portion disposed between the outer circumferential surface of the fixed blade and the inner circumferential surface of the cylindrical portion, and a spacer portion provided opposite to the outer circumferential side of the rotating blade and fitted and connected to the inner circumferential surface of the radial support portion of adjacent stacked plurality of spacers.

[0025] According to this configuration, by arranging the fixed wing and the rotating wing in order on the lower spacer that abuts against the inner peripheral surface of the cylindrical portion, and further arranging the upper spacer, the fixed wing, the spacer, and the rotating wing can be alternately arranged in multiple stages.

[0026] The invention according to claim 5 is the configuration according to claim 1, 2, 3, or 4, wherein the uppermost spacer includes an upper radial support portion disposed between the outer peripheral surface of the uppermost fixed wing and the inner peripheral surface of the cylindrical portion, and a lower radial support portion disposed between the outer peripheral surface of the fixed wing disposed below the uppermost fixed wing and the inner peripheral surface of the cylindrical portion, and a spacer portion provided on the outer peripheral side of the rotating wing at the second stage from the uppermost stage and connecting the upper radial support portion and the lower radial support portion, and provides a vacuum pump.

[0027] According to this configuration, since the uppermost spacer also serves as a structure for positioning two adjacent fixed wings, one above the other, of the uppermost fixed wing and the fixed wing disposed below the uppermost fixed wing, the total number of spacers can be reduced, and further cost reduction is possible.

[0028] The invention according to claim 6 is the configuration according to claim 1, 2, or 3, wherein the uppermost spacer is the uppermost fixed wing, and further has a radial positioning portion provided opposite to the outer peripheral side of the uppermost rotating wing, and provides a vacuum pump.

[0029] According to this configuration, since the uppermost spacer integrally provides a radial positioning portion provided opposite to the outer peripheral sides of the uppermost fixed wing and the rotating wing, it is not necessary to separately form the uppermost fixed wing, and further cost reduction is possible.

[0030] The invention described in claim 7 provides a vacuum pump in which, in the configuration described in claim 2 or 3, the base portion comprises a cylindrical base portion extending axially upward of the casing, the outer peripheral surface of which abuts against the inner surface of the lower radial positioning portion, and a horizontal base portion extending outward in a flange shape from the lower outer peripheral surface of the cylindrical base portion, the horizontal base portion being abutted against the lower surface of the cylindrical portion, and an O-ring is disposed between the horizontal base portion and the lower surface of the cylindrical portion to seal the space between the base portion and the cylindrical portion.

[0031] With this configuration, by arranging the sealing O-ring between the horizontal base portion and the lower surface of the cylindrical portion, it becomes easier to bring the lower radial positioning portion into contact with the circumferential surface of the cylindrical base portion, thereby improving positioning accuracy.

[0032] The invention described in claim 8 is a cylindrical part of a vacuum pump equipped with a turbo molecular mechanism having an intake port for drawing in gas from the outside, an exhaust port for exhausting the drawn-in gas to the outside, rotating blades and stationary blades arranged alternately in multiple stages in the axial direction, and a plurality of annular spacers stacked to position the stationary blades in the axial direction, wherein the cylindrical part is provided with radial positioning parts arranged to surround the outer circumference of the stacked plurality of spacers and provided at two positions, upper and lower, on the inner surface of the cylindrical part, and coaxially holding at least the uppermost spacer and the lowermost spacer of the stacked plurality of spacers.

[0033] This configuration allows the casing shape to be modified to support multiple spacers arranged in a multi-stage configuration with alternating fixed and rotary blades, in response to changes in the vacuum pump's specifications. This reduces the effort required for designing, cleaning, and managing the inventory of spacers and other components.

[0034] The invention described in claim 9 provides a base portion for a vacuum pump equipped with a turbo molecular mechanism, the base portion having an intake port for drawing in gas from the outside, an exhaust port for exhausting the drawn-in gas to the outside, rotating blades and stationary blades arranged alternately in multiple stages in the axial direction, and a plurality of annular spacers stacked to position the stationary blades in the axial direction, wherein the base portion is attached to the lower part of a cylindrical portion arranged to surround the outer circumference of the stacked plurality of spacers and is radially positioned with respect to the cylindrical portion.

[0035] This configuration allows the shape of the base to be changed to support multiple spacers arranged in a multi-stage configuration with alternating fixed and rotary blades, in response to changes in the specifications of the vacuum pump. This reduces the effort required for designing, cleaning, and managing the inventory of spacers and other components. [Effects of the Invention]

[0036] According to the invention, when a casing is placed over a multi-stage arrangement of fixed and rotary blades stacked alternately, the upper intake-side spacer and the lower exhaust-side spacer are both positioned axially and radially by positioning parts provided within the casing. As a result, the amount by which the entire multi-stage arrangement of spacers moves or tilts radially is suppressed (reduced). Therefore, even if the machining accuracy (tolerance) during the manufacturing of the casing and spacers is somewhat loosened, a certain positioning accuracy can be ensured, simplifying the production of the casing and spacers and reducing manufacturing costs. [Brief explanation of the drawing]

[0037] [Figure 1] This is a vertical cross-sectional view of a vacuum pump shown as one embodiment of the present invention. [Figure 2] These are enlarged views of Figure 1, where (a) is an enlarged view of section D in Figure 1, and (b) is an enlarged view of section E in Figure 1. [Figure 3] Figure 1 is a cross-sectional view of the spacer in the vacuum pump shown. [Figure 4] This is a vertical cross-sectional view of a vacuum pump shown as a first modified example of the present invention. [Figure 5] This is an enlarged view of section F in Figure 4. [Figure 6] This is a vertical cross-sectional view of a vacuum pump shown as a second modified example of the present invention. [Figure 7] This is a vertical cross-sectional view showing a conventional vacuum pump. [Figure 8] This is an enlarged view of section H in Figure 7. [Figure 9] Figure 7 is an enlarged cross-sectional view of the spacer in a conventional vacuum pump. [Modes for carrying out the invention]

[0038] The present invention aims to provide a vacuum pump, a cylindrical part, and a base part used in this vacuum pump that can ensure a certain positioning accuracy of spacers even with somewhat looser dimensional tolerances during manufacturing, and that can reduce the manufacturing cost of the vacuum pump. This is achieved by providing a vacuum pump equipped with a turbo molecular mechanism having rotating blades and fixed blades arranged alternately in multiple stages in the axial direction within a casing having an intake port for drawing in gas from the outside and an exhaust port for exhausting the drawn-in gas to the outside, wherein the casing is composed of two parts: a plurality of annular spacers stacked to position the fixed blades in the axial direction, a cylindrical part arranged to surround at least the outer circumference of the stacked plurality of spacers, and a base part attached to the lower part of the cylindrical part, and radial positioning parts provided at two positions, upper and lower, within the cylindrical part, respectively, which coaxially position and hold at least the uppermost and lowermost spacers of the stacked plurality of spacers.

[0039] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. In the following description, the same elements are denoted by the same reference numerals throughout the description of the embodiments. Furthermore, expressions indicating directions such as up and down and left and right are not absolute and are appropriate when each part of the vacuum pump of the present invention is depicted in that position, but should be changed and interpreted accordingly if that position changes. [Examples]

[0040] Figure 1 is a vertical cross-sectional view of a vacuum pump 10 shown as one embodiment of the present invention. Figure 2 is a partially enlarged view of Figure 1, where (a) is an enlarged view of section D in Figure 1, and (b) is an enlarged view of section E in Figure 1.

[0041] In Figure 1, the vacuum pump 10 comprises a casing 11 that forms the outer body of the vacuum pump 10, a rotor 13 having a rotor shaft 12 rotatably supported within the casing 11, a drive motor 14 that rotates the rotor shaft 12, and a stator column 15 that houses a part of the rotor shaft 12 and the drive motor 14.

[0042] The casing 11 has a cylindrical portion 11A and a base 11B provided at the lower part of the cylindrical portion 11A, forming the housing of the vacuum pump 10.

[0043] The cylindrical portion 11A of the casing 11 is formed as a cylindrical body with openings at the top and bottom, with the top opening serving as a gas intake port 16. An upper flange portion 17 is integrally formed on the outer circumference of the upper opening, and a lower flange portion 18 is integrally formed on the outer circumference of the lower opening. An annular O-ring recess 18a is formed on the lower surface of the lower flange portion 18 for positioning and arranging an O-ring 19 for sealing. On the inner circumferential surface side of the cylindrical portion 11A, an upper radial positioning portion (also called the "upper positioning portion") 20 is provided at the top of the cylindrical portion 11A, and a lower radial positioning portion (also called the "lower positioning portion") 21 is provided at the bottom of the cylindrical portion 11A.

[0044] The upper radial positioning portion 20 consists of a first annular wall portion 20a that protrudes horizontally inward from the inner circumferential surface 11AC of the cylindrical portion 11A, and a second annular wall portion 20b that is recessed vertically upward from the inner surface of the first annular wall portion 20a and protrudes horizontally inward from that recessed position.

[0045] The lower radial positioning section 21 uses a portion of the inner circumferential surface 11AC of the cylindrical section 11A, that is, the lower inner circumferential surface.

[0046] The base 11B of the casing 11 integrally includes a cylindrical base portion 22 that extends axially upward from the casing 11, with its outer peripheral surface 22a fitted and connected to the inner surface (inner peripheral surface 11AC) of the lower radial positioning portion 21 of the cylindrical portion 11A, and an annular horizontal base portion 23 that extends horizontally outward in a flange shape from the lower outer peripheral surface of the cylindrical base portion 22 and abuts against the lower surface of the lower flange portion 18 of the cylindrical portion 11A. The upper part of the cylindrical base portion 22 is provided with a small diameter portion 22b to which the lower part of the first radial support portion 39a of the annular spacer 39, which will be described later, is attached.

[0047] Then, when the cylindrical base portion 22 and the cylindrical portion 11A are fitted together from the lower end of the cylindrical portion 11A, the cylindrical portion 11A is connected to the base 11B in a state where it is resting on the base 11B, as shown in Figure 1. In this connection, an O-ring 19 for sealing is interposed between the lower flange portion 18 and the horizontal base portion 23, and the lower flange portion 18 and the horizontal base portion 23 are further fixed together with a bolt 25, thereby integrating the cylindrical portion 11A and the base 11B.

[0048] The rotor 13 comprises a rotor shaft 12 and rotor blades 26 fixed to the upper part of the rotor shaft 12 and arranged concentrically with respect to the axis O1 of the rotor shaft 12. In this embodiment, 10 stages of rotor blades 26 are provided.

[0049] The rotor blades 26 consist of blades inclined at a predetermined angle and are integrally formed on the upper outer surface of the rotor 13. Multiple rotor blades 26 are also arranged radially around the axis O1 of the rotor 13.

[0050] The rotor shaft 12 is non-contact supported by a magnetic bearing 27. The magnetic bearing 27 comprises a radial electromagnet 28 and an axial electromagnet 29. The radial electromagnet 28 and the axial electromagnet 29 are connected to a control unit (not shown).

[0051] The control unit controls the excitation current of the radial electromagnet 28 and the axial electromagnet 29 based on the detected values ​​of the radial displacement sensor 28a and the axial displacement sensor 29a, thereby supporting the rotor shaft 12 in a levitated state at a predetermined position.

[0052] The upper and lower parts of the rotor shaft 12 are inserted into the touchdown bearing 30. If the rotor shaft 12 becomes uncontrollable, the high-speed rotating rotor shaft 12 will come into contact with the touchdown bearing 30, preventing excessive damage to the vacuum pump 10.

[0053] The rotor 13 is integrally attached to the rotor shaft 12 by inserting the upper part of the rotor shaft 12 through the boss hole 31, and then inserting bolts 32 through the rotor flange 33 and screwing them into the shaft flange 34. Hereinafter, the axial direction of the rotor shaft 12 will be referred to as "axial direction M," and the radial direction of the rotor shaft 12 will be referred to as "radial direction R."

[0054] The drive motor 14 comprises a rotor 35 attached to the outer circumference of the rotor shaft 12, and a stator 36 arranged to surround the rotor 35. The stator 36 is connected to a control unit (not shown) described above, and the rotation of the rotor 13 is controlled by the control unit.

[0055] The stator column 15 is mounted on the base 11B and fixed to the base 11B via bolts 37.

[0056] Fixed blades 38 are provided near the axial direction of the rotor blades 26, 26. That is, the rotor blades 26 and fixed blades 38 are arranged alternately and in multiple stages along the axial direction M. In this embodiment, 10 stages of fixed blades 38 are provided.

[0057] The fixed wing 38 is formed in an annular shape and comprises blades inclined in the opposite direction to the rotor blade 26 and rings connected to both ends of the blades. It is positioned in the axial direction M and radial direction R by being sandwiched between spacers 39 that are stacked on the inner circumferential surface of the cylindrical portion 11A of the casing 11. In addition, multiple blades of the fixed wing 38 are also installed radially around the axis O1 of the rotor 13.

[0058] Furthermore, a gas exhaust port 24, which leads to the outside, is provided on the outer circumferential surface of the cylindrical base portion 22 of the base 11B. The gas exhaust port 24 is connected to an auxiliary pump (not shown). The vacuum pump 10, through the interaction of the rotating blades 26 and the fixed blades 38, transfers the gas (gas) G drawn in from the gas intake port 16 from the upper to the lower axial direction M, and exhausts it to the outside through the gas exhaust port 24.

[0059] The lowest fixed wing 38 is mounted on the small-diameter portion 22b of the cylindrical base portion 22 on the base 11B. Specifically, the base end of the fixed wing 38 is supported in the axial direction M and radial direction R by being sandwiched between the upper surface of the cylindrical base portion 22 and the small-diameter portion 22b and the spacer 39.

[0060] The spacer 39 is a roughly cylindrical fixing member that extends along the axial direction of the casing 11 and comprises a first radial support portion 39a that circumferentially faces the outer circumferential surface of the fixed blade 38 and faces the inner circumferential surface 11AC of the cylindrical portion 11A with a small gap between them, and a second radial support portion 39b that circumferentially faces the outer circumferential surface of the rotor blade 26 and abuts against the inner circumferential surface of the first radial support portion 39a. Furthermore, a small diameter portion (step portion) 39c is formed on the outer circumference of the second radial support portion 39b, to which the lower part of the first radial support portion 39a of the spacer 39 that is stacked on top is attached.

[0061] The amount of radial recess in the small diameter portion 39c of the spacer 39 is approximately equal to the radial thickness of the first radial support portion 39a, so that when the lower part of the first radial support portion 39a of the upper spacer 39 is installed, the outer circumferential surface of the upper spacer 39 and the outer circumferential surface of the lower spacer 39 are flush with each other. On the other hand, the amount of radial recess on the inner circumferential surface side of the first radial support portion 39a of the spacer 39 is approximately equal to the radial thickness of the second radial support portion 39b, so that when the upper part of the second radial support portion 39b of the lower spacer 39 is installed, the inner circumferential surface of the upper spacer 39 and the inner circumferential surface of the lower spacer 39 are flush with each other. Furthermore, the axial height of each spacer 39 is arbitrarily set in proportion to the height (thickness) of the blades of the rotor blade 26 and the fixed blade 38.

[0062] The assembly of the fixed blades 38 and spacers 39 of the vacuum pump 10 is carried out by first placing the rotor 13, which is the rotating part, on the base 11B, then placing the lowest fixed blade 38 on the small diameter portion 22b of the cylindrical base portion 22 of the base 11B, and then stacking the lowest spacers 39 on top. At this time, the lowest spacer 39 is installed so that the lowest fixed blade 38 and the small diameter portion 22b are enclosed within the first radial support portion 39a, and the small diameter portion 22b and the first radial support portion 39a are fitted and connected to position the lowest spacer 39 relative to the base 11B. In addition, the arrangement of the lowest spacer 39 ensures that the lowest rotating blade 26 is enclosed within this spacer 39 in a non-contact state.

[0063] Next, the second fixed wing 38 is placed on the second radial support portion 39b of the final stage spacer 39, and then the second stage spacer 39 is stacked on top. At this time, the second stage spacer 39 is positioned so that the bottom stage fixed wing 38 and the second radial support portion 39b of the bottom stage spacer 39 are enclosed within the first radial support portion 39a of the second stage spacer 39, and the second radial support portion 39b of the bottom stage spacer 39 and the first radial support portion 39a of the second stage spacer 39 are fitted and connected, respectively, to position the second stage spacer 39 relative to the bottom stage spacer 39. Then, with the arrangement of the second stage spacer 39, the bottom stage rotor wing 26 is enclosed within this spacer 39 in a non-contact state. By repeating this process sequentially thereafter, a gas transfer mechanism 40 having a rotating section and a cylindrical fixed section in which rotor wing 26 and fixed wing 38 are arranged alternately in multiple stages in the axial direction is assembled and formed.

[0064] After assembling the fixed wings 38 and spacers 39, the gas transfer mechanism 40 is housed inside the casing 11. The casing 11 is placed over the uppermost spacer 39 from above, thereby housing the gas transfer mechanism 40 inside the casing 11. The process of housing the mechanism inside the casing 11 is performed by inserting the uppermost spacer 39 through the lower opening of the cylindrical section 11A, and then dropping the casing 11 using the gas transfer mechanism 40 as a guide. At this time, the inner circumferential surface 11AC of the cylindrical section 11A slides against the outer circumferential surface of the spacer 39 as it is dropped in. When it is inserted almost to the final position, the lower radial positioning part 21 provided on the inner circumferential surface 11AC of the cylindrical section 11A comes into contact with the outer circumferential surface 22a of the cylindrical base section 22, and the lower side of the gas transfer mechanism 40 is positioned relative to the base 11B. Furthermore, when the casing 11 is lowered to approximately its final position, the upper radial positioning portion 20 provided on the inner circumferential surface 11AC of the cylindrical portion 11A corresponds to the uppermost spacer 39, and the upper part of the uppermost spacer 39 is fitted and connected to the first annular wall portion 20a and the second annular wall portion 20b, thereby positioning the upper side of the gas transfer mechanism 40 relative to the casing 11. In other words, the upper and lower positions of the gas transfer mechanism 40 are positioned by the upper radial positioning portion 20 and the lower radial positioning portion 21, and the movement or tilting of the entire multi-stage spacer 39 in the radial direction R is prevented (mitigated).

[0065] In this configuration, the vacuum pump 10 has an upper flange portion 17 of the casing 11, which is provided with a gas intake port 16 as described above, attached to a vacuum container such as a chamber (not shown), and an auxiliary pump (not shown) is attached to a gas exhaust port 24 provided on the base 11B. In this state, when the drive motor 14 of the vacuum pump 10 is driven, the rotor blades 26 rotate at high speed together with the rotor 13. As a result, gas G from the gas intake port 16 flows into the vacuum pump 10, and the gas G is sequentially transported through the gas transfer mechanism 40 and exhausted from the gas exhaust port 24 of the base 11B. In other words, the vacuum container is evacuated.

[0066] Therefore, in the vacuum pump 10 of this embodiment, the upper and lower positions of the gas transfer mechanism 40 are positioned by the upper radial positioning section 20 and the lower radial positioning section 21, and the structure is designed to suppress the movement or tilting of the entire multi-stage spacer 39 in the radial direction, thus suppressing (reducing) the movement or tilting of the entire multi-stage spacer 39 in the radial direction R. As a result, even if the machining accuracy (tolerance) during the manufacturing of the casing 11 and spacer 39 is made somewhat looser, a certain positioning accuracy can be ensured, making the manufacturing of the casing 11 and spacer 39 easier and reducing manufacturing costs. In conventional structures where only the upper position of the gas transfer mechanism is positioned, the tolerances of the inner circumference dimension A of the first radial support section, the outer circumference dimension B of the spacer, and the outer circumference dimension C of the small diameter section (step section) were required to be small and strict, but in the present invention, they can be made about 30% looser compared to the conventional structure, simplifying the machining and improving manufacturing costs.

[0067] Figure 4 is a vertical cross-sectional view of a vacuum pump 10, which is shown as a first modified example of the vacuum pump shown in Figure 1. The first modified example shown in Figure 4 is a modification of the uppermost spacer 139, and the other components are the same as those of the vacuum pump 10 shown in Figures 1 and 2. Therefore, the same components are denoted by the same reference numerals and redundant explanations are omitted.

[0068] The annular uppermost spacer 139 shown in Figure 4 is positioned between the outer circumferential surface of the uppermost fixed wing 38(38a) and the outer circumferential surface of the fixed wing immediately below the uppermost fixed wing 38a, i.e., the second fixed wing 38(38b) from the top and the outer circumferential surface of the second rotor blade 26a. The uppermost spacer 139 consists of a spacer portion 139d that maintains the axial distance between the uppermost fixed wing 38(38a) and the second fixed wing 38(38b) from the top, a first radial support portion 139a that extends vertically downward in the axial direction from the lower outer circumferential edge of the spacer portion 139d as a lower radial support portion, and a second radial support portion 139b that extends vertically upward in the axial direction from the upper outer circumferential edge of the spacer portion 139d as an upper radial support portion.

[0069] Then, the uppermost spacer 139 is positioned such that the first radial support portion 139a encloses the second fixed wing 38b from the top, and the spacer portion 139d encloses the second rotary wing 26 from the top, and is fitted and connected to the small diameter portion (step portion) 139c of the second spacer 39 from the top, and the uppermost spacer 139 is stacked on top of the second spacer 39 from the top to position it. Next, the final fixed wing 38a is placed on the upper surface of the spacer portion 139d of the uppermost spacer 139, and then the cylindrical portion 11A of the casing 11 is placed over it.

[0070] Furthermore, when the cylindrical portion 11A is placed over the gas transfer mechanism, the upper radial positioning portion 20 provided on the inner circumferential surface 11AC of the cylindrical portion 11A corresponds to the uppermost spacer 139, and the upper part of the uppermost spacer 139 abuts against the first annular wall portion 20a, while the upper surface of the final spacer 139 abuts against the second annular wall portion 20b, thereby positioning the upper side of the gas transfer mechanism 40 relative to the casing 11. On the other hand, the lower radial positioning portion 21 of the casing 11 abuts against the outer circumferential surface 22a of the cylindrical base portion 22, positioning the lower side of the gas transfer mechanism 40 relative to the base 11B.

[0071] Therefore, in this first modified example, the vacuum pump 10 also has the upper and lower positions of the gas transfer mechanism 40 positioned by the upper radial positioning section 20 and the lower radial positioning section 21, and the entire multi-stage spacer 39 is prevented from moving or tilting in the radial direction. As a result, in this modified structure, it is possible to eliminate the space that circumfers and faces the uppermost rotor blade 26, reducing the number of parts compared to the vacuum pump 10 shown in Figure 1, and thus reducing manufacturing costs.

[0072] Figure 6 is a vertical cross-sectional view of a vacuum pump 10, which is shown as a second modified example of the vacuum pump shown in Figures 1 and 2. In the second modified example shown in Figure 6, the uppermost spacer 239 and the uppermost fixed blade 238 are integrated, and the other components are the same as those in Figures 1 and 2. Therefore, the same components are denoted by the same reference numerals and redundant explanations are omitted.

[0073] The uppermost annular spacer 239 shown in Figure 6 is an annular member, and the uppermost fixed wing 238 is integrally provided with it, extending substantially horizontally from the inner circumferential surface of the uppermost spacer 239 toward the axis O1. Furthermore, the lower part of the spacer 239 is provided with a first radial support portion 239a that engages with and connects to the second radial support portion 39b of the second spacer 39 from the top, and the upper part is provided with a second radial support portion 239b that abuts against and engages with the first annular wall portion 20a and the second annular wall portion 20b of the upper radial positioning portion 20 as a radial positioning portion.

[0074] Then, the uppermost spacer 239 is positioned such that the second radial support portion 239b encloses the uppermost rotor blade 26, and the first radial support portion 239a is fitted and connected to the small diameter portion (step portion) 39c of the second uppermost spacer 39, thereby stacking the uppermost spacer 239 on top of the second uppermost spacer 39. After that, the cylindrical portion 11A of the casing 11 is placed over it.

[0075] Furthermore, when the cylindrical portion 11A of the casing 11 is placed over the gas transfer mechanism 40, the upper radial positioning portion 20 provided on the inner circumferential surface 11AC of the cylindrical portion 11A corresponds to the uppermost spacer 239, and the upper part of the uppermost spacer 239 is fitted and connected to the first annular wall portion 20a, and the upper surface of the second radial support portion 239b abuts against the second annular wall portion 20b, thereby positioning the upper side of the gas transfer mechanism 40 relative to the casing 11. On the other hand, the lower radial positioning portion 21 of the casing 11 abuts against the outer circumferential surface 22a of the cylindrical base portion 22, thereby positioning the lower side of the gas transfer mechanism 40 relative to the base 11B.

[0076] Therefore, in this second modified example, the vacuum pump 10 also has the upper and lower positions of the gas transfer mechanism 40 positioned by the upper radial positioning section 20 and the lower radial positioning section 21, and the entire multi-stage spacer 39 is prevented from moving or tilting in the radial direction. Furthermore, in the structure of this second modified example, the uppermost spacer 239 and the uppermost fixed blade 238 are integrated, so the number of parts is reduced compared to the vacuum pump 10 shown in Figure 1, making it possible to reduce manufacturing costs.

[0077] Furthermore, the present invention can be modified in various ways as long as it does not depart from the spirit of the invention, and it goes without saying that the present invention extends to such modified forms.

[0078] 10 Vacuum pump 11. Casing (enclosure) 11A Cylindrical section 11AC Inner surface 11B Bass 12 Rotor Shaft 13 Rotors 14 Drive motor 15 Status Column 16 Gas intake 17 Upper flange section 18 Lower flange section 18a Recess for O-ring 19 O-rings 20 Upper radial positioning section 20a First annular wall section 20b Second annular wall section 21 Lower radial positioning section 22 Cylindrical base section 22a Outer surface 22b Small diameter section 23 Horizontal base section 24 Gas exhaust port 25 volts 26 Rotary blades 27 Magnetic bearings 28 Radial electromagnet 28a Radial directional bias sensor 29 Axial electromagnet 29a Axial directional displacement sensor 30 Touchdown bearings 31 Boss holes 32 volts 33 Rotor flange 34 Shaft flange 35 rotor 36 Stator 37 volts 38 fixed wing 38a Uppermost fixed wing 38b Second fixed wing from the top 39 Spacers 39a First radial support 39b Second radial support section 39c Small diameter section (stepped section) 139 Spacer 139a First radial support section (lower radial support section) 139b Second radial support section (upper radial support section) 139d Spacer section 238 Uppermost fixed wing 239 Top spacer 239a First radial support section (lower radial support section) 239b Second radial support section (upper radial support section and radial positioning section) 40 Gas transfer mechanism M Axial direction R radial direction G gas O1 axis

Claims

1. A vacuum pump including a turbomolecular mechanism having rotating blades and fixed blades arranged alternately in multiple stages in an axial direction within a casing having an intake port for drawing in gas from the outside and an exhaust port for exhausting the drawn-in gas to the outside, a plurality of annular spacers stacked in layers to position the stator blades in the axial direction; the casing being composed of two parts, a cylindrical part arranged to surround the outer periphery of at least the plurality of stacked spacers, and a base part attached to a lower part of the cylindrical part; radial positioning portions provided at two positions, one above the other, within the cylindrical portion, and coaxially holding at least an uppermost spacer and a lowermost spacer of the plurality of stacked spacers; A vacuum pump comprising:

2. an upper radial positioning portion on the inner circumferential surface of the cylindrical portion is provided to correspond to the outer circumferential surfaces of the plurality of spacers; 2. The vacuum pump according to claim 1, wherein the radial positioning portion on the lower side of the inner circumferential surface of the cylindrical portion is provided to correspond to a side surface of the base portion.

3. 3. The vacuum pump according to claim 2, wherein the upper radial positioning portion is provided to correspond to an outer peripheral surface of the uppermost spacer.

4. The plurality of spacers are a radial support portion disposed between an outer peripheral surface of the fixed blade and an inner peripheral surface of the cylindrical portion; spacer portions provided opposite to the outer circumferential side of the rotor blades and fitted and coupled to inner circumferential surfaces of the radial support portions of the plurality of spacers stacked adjacent to each other; 4. The vacuum pump according to claim 1, 2 or 3, characterized in that it comprises:

5. The top spacer is an upper radial support portion disposed between an outer peripheral surface of the uppermost fixed blade and an inner peripheral surface of the cylindrical portion; a lower radial support portion disposed between an outer peripheral surface of the stator blade disposed below the uppermost stator blade and an inner peripheral surface of the cylindrical portion; a spacer portion provided on an outer circumferential side of the rotor blades in the second stage from the top, the spacer portion connecting the upper radial support portion and the lower radial support portion; 5. A vacuum pump according to claim 1, 2, 3 or 4.

6. 4. The vacuum pump according to claim 1, wherein the spacer of the uppermost stage is the fixed vane of the uppermost stage, and further includes the radial positioning portion provided opposite to the outer circumferential side of the rotary vane of the uppermost stage.

7. The base portion is a cylindrical base portion extending axially upward of the casing, the outer circumferential surface of which abuts against the inner surface of the lower radial positioning portion; a horizontal base portion extending outward from the lower outer periphery of the cylindrical base portion in a flange-like shape and abutting against the lower surface of the cylindrical portion; Equipped with 4. The vacuum pump according to claim 2, wherein an O-ring is disposed between the horizontal base portion and the lower surface of the cylindrical portion to seal between the base portion and the cylindrical portion.

8. an intake port for drawing in gas from the outside and an exhaust port for exhausting the drawn-in gas to the outside; Rotating blades and fixed blades arranged alternately in multiple stages in the axial direction; a plurality of annular spacers stacked in stages to position the fixed vanes in the axial direction; the cylindrical portion is disposed so as to surround the outer periphery of the plurality of stacked spacers, radial positioning portions provided at two positions, one above the other, on the inner peripheral surface of the cylindrical portion, and coaxially holding at least an uppermost spacer and a lowermost spacer of the plurality of stacked spacers; A cylindrical portion comprising:

9. an intake port for drawing in gas from the outside and an exhaust port for exhausting the drawn-in gas to the outside; Rotating blades and fixed blades arranged alternately in multiple stages in the axial direction; a plurality of annular spacers stacked in stages to position the fixed vanes in the axial direction; the base portion is attached to a lower portion of a cylindrical portion that is arranged to surround the outer periphery of the stacked spacers, The cylindrical portion is positioned radially. The base part is characterized by:

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