Vacuum pump

Abstract

Provided is a vacuum pump suitable for ensuring the balance of a rotor including a plurality of rotating vanes and a particle transport portion and preventing the backflow of particles from the vacuum pump to the vacuum chamber side. The vacuum pump (P1) has, between a suction port and a discharge port, a plurality of discharge stages (PT) that discharge gas molecules, and a particle transport portion (PN) that transports particles in the direction of discharge of the gas molecules. The particle transport portion functions as a mechanism that transports particles in the direction of discharge of the gas molecules by having at least a portion of the height of the upstream end of the plurality of rotating vanes (7) that constitute the uppermost stage be increased or decreased, so that the entire uppermost stage becomes a stepped structure in which the height of the upstream end differs. The rotor (R) that is composed of the plurality of rotating vanes and the particle transport portion, and a cylindrical portion (6) that supports the plurality of rotating vanes, is balanced with respect to the entire rotor, with respect to the imbalance that is caused by the presence of the rotating vane whose height of the upstream end is higher than that of the other rotating vanes due to the aforementioned stepped structure.

Description

TECHNICAL FIELD

[0001] The present application relates to a vacuum pump used as a gas exhaust mechanism of a processing chamber in a semiconductor manufacturing apparatus, a flat panel display manufacturing apparatus, a solar cell panel manufacturing apparatus, and other vacuum chambers, and particularly, to a vacuum pump adapted to ensure the balance of a rotating body as a whole including a plurality of rotating blades and a particle transporting portion and prevent the backflow of particles from the vacuum pump to the vacuum chamber side. BACKGROUND

[0002] Vacuum pumps such as turbo molecular pumps and screw groove pumps are used for the exhaust of vacuum chambers requiring high vacuum. Figure 22 is a schematic diagram of an exhaust system in which a conventional vacuum pump is employed as a gas exhaust mechanism of a vacuum chamber.

[0003] Configuration Figure 22 The conventional vacuum pump Z of the exhaust system of

[0004] Each of the exhaust stages PT in the conventional vacuum pump Z is structured to exhaust gas molecules by a plurality of rotating blades 7 and fixed blades 8 radially arranged at a predetermined interval in each of the exhaust stages PT.

[0005] In the gas molecule exhaust structure as described above, the rotating blades 7 are integrally formed on the outer circumferential surface of the rotor 6 rotatably supported by a bearing mechanism such as a magnetic bearing, and rotate at high speed together with the rotor 6. On the other hand, the fixed blades 8 are fixed to the inner surface of the housing 1.

[0006] In the exhaust system of Figure 22 In the exhaust system of

[0007] Further, the deposits attached / accumulated to the inner wall surface of the vacuum chamber CH, the deposits attached / accumulated to the pressure adjusting valve BL, and the like are also peeled off due to vibration or the like and fall down to the suction port 2 of the vacuum pump Z due to the self weight.

[0008] Patent Document 1 discloses a mechanism for preventing the backflow of particles as described above (hereinafter referred to as "particle backflow prevention mechanism"). That is, the vacuum pump of this Document 1 has a plurality of exhaust stages for exhausting gas molecules between the suction port and the exhaust port, and in the uppermost stage of the plurality of exhaust stages, a particle transport portion (referred to as a particle transport stage in this Document 1) is provided as a particle backflow prevention mechanism.

[0009] The particle transport portion is such that the height of the upstream end of at least a portion of the plurality of rotating blades constituting the uppermost stage of the exhaust stage is increased or decreased, whereby the entire uppermost stage of the exhaust stage becomes a stepped structure in which the heights of the upstream ends are different, thereby enabling the particles to be transported in the exhaust direction of the gas molecules.

[0010] However, in the particle backflow prevention mechanism as in Patent Document 1 as described above, there is a problem that the rotating blades whose upstream end height is higher than that of the other rotating blades due to the stepped structure exist, the balance of the entire rotating body (constituted by the plurality of rotating blades, the particle transport portion, and the cylindrical portion supporting the plurality of rotating blades) is disrupted due to the existence of the rotating blades, vibrations and the like occur during the operation of the vacuum pump, and the operation of the vacuum pump is hindered.

[0011] Patent Document 1: WO2018 / 174013. SUMMARY

[0012] The present application is made to solve the aforementioned problems, and aims to provide a vacuum pump that is suitable for ensuring the balance of the entire rotating body including the plurality of rotating blades and the particle transport portion and preventing the backflow of particles from the vacuum pump to the vacuum chamber side.

[0013] To achieve the aforementioned object, the present application is a vacuum pump having a plurality of exhaust stages for exhausting gas molecules between a suction port and an exhaust port, and in the plurality of exhaust stages, a particle transport portion is provided, the particle transport portion being such that the height of the upstream end of at least a portion of the plurality of rotating blades constituting the uppermost stage of the exhaust stage is increased or decreased, whereby the entire uppermost stage of the exhaust stage becomes a stepped structure in which the heights of the upstream ends are different, thereby transporting particles in the exhaust direction of the gas molecules, characterized in that the rotating body constituted by the plurality of rotating blades, the particle transport portion, and the cylindrical portion supporting the plurality of rotating blades is such that, with respect to the entire rotating body, the imbalance due to the existence of the rotating blades whose upstream end height becomes higher than that of the other rotating blades due to the stepped structure is corrected.

[0014] In the aforementioned present application, it can also be characterized in that a portion of the rotating blades whose upstream end height becomes higher than that of the other rotating blades due to the stepped structure or the rotating blades close to the rotating blades is removed, thereby correcting the imbalance.

[0015] In the foregoing invention, the feature can also be that the blade surface of the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade is removed by a predetermined amount on the back side in the rotating direction where the contribution of the exhaust of the aforementioned gas molecules is less, thereby correcting the aforementioned imbalance.

[0016] In the foregoing invention, the feature can also be that the downstream end edge of the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade is removed by a predetermined amount, thereby correcting the aforementioned imbalance.

[0017] In the foregoing invention, the feature can also be that a hole is provided on the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade, thereby correcting the aforementioned imbalance.

[0018] In the foregoing invention, the feature can also be that a groove is formed on the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade, thereby correcting the aforementioned imbalance.

[0019] In the foregoing invention, the feature can also be that the radial length of the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade is set to be shorter than the radial length of the aforementioned other rotating blades other than them, thereby correcting the aforementioned imbalance.

[0020] In the foregoing invention, the feature can also be that the upstream end of the rotating blade close to the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure is removed by a predetermined amount, thereby correcting the aforementioned imbalance.

[0021] In the foregoing invention, the feature can also be that a mass is added to the rotating blade on the side opposite to the rotation center of the aforementioned rotating blade whose height at the aforementioned upstream end becomes higher than the aforementioned other rotating blades due to the aforementioned step structure or the rotating blade close to the aforementioned rotating blade, thereby correcting the aforementioned imbalance.

[0022] In the foregoing invention, the feature can also be that the downstream end edge of the rotating blade on the opposite side from the rotating center of the rotating blade located on the higher side than the other rotating blades due to the step structure of the upstream end is longer than that of the other rotating blades, thereby correcting the imbalance.

[0023] In the foregoing invention, the feature can also be that the radial length of the rotating blade on the opposite side from the rotating center of the rotating blade located on the higher side than the other rotating blades due to the step structure of the upstream end is longer than that of the other rotating blades, thereby correcting the imbalance.

[0024] In the foregoing invention, the feature can also be that the thickness of the rotating blade on the opposite side from the rotating center of the rotating blade located on the higher side than the other rotating blades due to the step structure of the upstream end is increased than that of the other rotating blades, thereby correcting the imbalance.

[0025] In the foregoing invention, the feature can also be that the arrangement interval of at least two or more rotating blades on the same side as the rotating blade located on the higher side than the other rotating blades due to the step structure of the upstream end is larger than that of the other rotating blades, thereby correcting the imbalance.

[0026] In the foregoing invention, the feature can also be that the arrangement interval of at least two or more rotating blades on the opposite side from the rotating blade located on the higher side than the other rotating blades due to the step structure of the upstream end is narrower than that of the other rotating blades, thereby correcting the imbalance.

[0027] In the foregoing invention, the feature can also be that the imbalance is corrected by the exhaust section other than the uppermost section.

[0028] In the foregoing invention, the feature can also be that the imbalance is corrected by the concave or convex portion attached to the outer peripheral surface of the cylindrical portion.

[0029] In the foregoing invention, the feature can also be that the imbalance is corrected by cutting a part of the gasket for fastening the rotating body and the rotating shaft of the rotating body.

[0030] Furthermore, the present invention is a rotating body of a vacuum pump, wherein the vacuum pump has multiple exhaust sections for venting gas molecules from the intake port to the exhaust port, and each of the multiple exhaust sections includes a particle transport section. The particle transport section is configured such that the height of at least a portion of the upstream ends of the multiple rotating blades constituting the uppermost exhaust section is increased or decreased, thereby forming a stepped structure with different upstream end heights as a whole for the uppermost exhaust section, thereby transporting particles in the direction of venting the gas molecules. The rotating body, which is composed of the multiple rotating blades, the particle transport section, and a cylindrical portion supporting the multiple rotating blades, corrects for the imbalance caused by the presence of rotating blades whose upstream end height is higher than that of other rotating blades due to the stepped structure.

[0031] Furthermore, the present invention is a vacuum pump having multiple exhaust sections for venting gas molecules and a particle conveying section for conveying particles in the exhaust direction of the gas molecules between the intake port and the exhaust port. The invention is characterized in that the rotating body composed of the multiple exhaust sections, the particle conveying section, and a cylindrical portion supporting the multiple exhaust sections corrects the imbalance caused by the arrangement of the particle conveying section for the rotating body as a whole.

[0032] According to the present invention, particles falling from the vacuum chamber to the suction port of the vacuum pump are transported in the exhaust direction of gas molecules by means of a particle transport section with a stepped structure. Furthermore, the imbalance of the entire rotating body caused by the presence of a rotating blade whose upstream end height is higher than that of other rotating blades due to the stepped structure or the imbalance of the entire rotating body caused by the arrangement of the particle transport section can be corrected. Therefore, a vacuum pump suitable for ensuring the balance of the entire rotating body and preventing the backflow of particles from the vacuum pump to the vacuum chamber side can be provided. Attached Figure Description

[0033] Figure 1 This is a cross-sectional view of the vacuum pump that utilizes the present invention.

[0034] Figure 2 (a) Viewed from the outer circumferential side of the rotor Figure 1 A diagram illustrating the state of the particle delivery section in a vacuum pump. Figure 2 (b) is Figure 2 (a) View from direction A Figure 2 (c) is Figure 2 (a) View from direction B.

[0035] Figure 3 This is an illustration of the potential collision zone of particles falling from a vacuum pump that does not have a particle delivery unit.

[0036] Figure 4 It is equipped with a particle transport unit Figure 1Explanatory view of collision possible area of particles fallen in vacuum pump.

[0037] Figure 5 Explanatory view of rotating body before correction of unbalance.

[0038] Figure 6 Explanatory view of basic thinking mode of unbalance correction of rotating body as a whole.

[0039] Figure 7 Explanatory view of first unbalance correction structure.

[0040] Figure 8 Explanatory view of first unbalance correction structure.

[0041] Figure 9 Explanatory view of first unbalance correction structure.

[0042] Figure 10 Explanatory view of first unbalance correction structure.

[0043] Figure 11 Explanatory view of first unbalance correction structure.

[0044] Figure 12 Explanatory view of first unbalance correction structure.

[0045] Figure 13 Explanatory view of rotating body to which first unbalance correction structure of Figure 12 Explanatory view of rotating body to which first unbalance correction structure of

[0046] Figure 14 Explanatory view of second unbalance correction structure.

[0047] Figure 15 Explanatory view of second unbalance correction structure.

[0048] Figure 16 Explanatory view of third unbalance correction structure.

[0049] Figure 17 Explanatory view of third unbalance correction structure.

[0050] Figure 18 Explanatory view of fourth unbalance correction structure.

[0051] Figure 19 Explanatory view of sixth unbalance correction structure.

[0052] Figure 20 Explanatory view of sixth unbalance correction structure.

[0053] Figure 21 Explanatory view of seventh unbalance correction structure, (a) is cross-sectional view of rotating body provided with washer, (b) is plan view of the washer.

[0054] Figure 22 is a schematic diagram of an exhaust system in which a conventional vacuum pump is used as a gas exhaust mechanism of a vacuum chamber. DETAILED DESCRIPTION

[0055] Hereinafter, a most preferable mode for carrying out the present application will be explained in detail with reference to the drawings.

[0056] In the present embodiment, a so-called compound vane type vacuum pump provided with a turbo molecular pump section composed of a plurality of exhaust stages and a screw groove exhaust stage is explained as an example of a vacuum pump, but the present embodiment can also be applied to a vacuum pump having only a turbo molecular pump section.

[0057] Figure 1 is a sectional view of a vacuum pump to which the present application is applied.

[0058] If reference is made to Figure 1 , the vacuum pump P1 of this figure is provided with a cylindrical outer shell 1, a cylindrical section 6 (rotor) disposed in the outer shell 1, a support mechanism capable of rotatably supporting the cylindrical section 6, and a drive mechanism that rotates and drives the cylindrical section 6.

[0059] The outer shell 1 is a bottomed cylinder, and the cylindrical pump shell 1A and the bottomed cylindrical pump base 1B are integrally joined in the axial direction thereof by means of fastening bolts, and the upper end portion side of the pump shell 1A is opened as a gas suction port 2 for sucking gas, and further, a gas exhaust port 3 for exhausting gas to the outside of the outer shell 1 is provided on the lower end portion side of the pump base 1B.

[0060] The gas suction port 2 is connected to a vacuum chamber CH (refer to Figure 22 ) that becomes a high vacuum such as a processing chamber of a semiconductor manufacturing apparatus via a pressure adjusting valve BL (refer to Figure 22 ). The gas exhaust port 3 is connected in communication to an auxiliary pump not shown.

[0061] A cylindrical stator column 4 in which various electric components are built in is provided in the central portion in the pump shell 1A. In the vacuum pump P1 of Figure 1 , the stator column 4 is formed as a member separate from the pump base 1B and is threadedly fixed to the inner bottom of the pump base 1B, so as to be erected on the pump base 1B, but as a further other embodiment, the stator column 4 can also be integrally erected on the inner bottom of the pump base 1B.

[0062] The aforementioned cylindrical section 6 is provided on the outer side of the stator column 4. The cylindrical section 6 is enclosed in the pump shell 1A and the pump base 1B, and is in a cylindrical shape that surrounds the outer periphery of the stator column 4.

[0063] A rotary shaft 5 (rotor shaft) is provided inside the stator column 4. The rotary shaft 5 is configured such that its upper end portion faces the direction of the suction port 2 and its lower end portion faces the direction of the pump base IB. Further, the rotary shaft 5 is rotatably supported by magnetic bearings (specifically, two sets of radial magnetic bearings MB1 and one set of axial magnetic bearings MB2). Furthermore, a drive motor MO is provided inside the stator column 4, and the rotary shaft 5 is rotationally driven about its axis by the drive motor MO.

[0064] The upper end portion of the rotary shaft 5 protrudes upward from the cylindrical upper end surface of the stator column 4, and the upper end side of the cylindrical portion 6 is integrally fixed to the protruding upper end portion of the rotary shaft 5 by a fastening mechanism such as a bolt. Thus, the cylindrical portion 6 is rotatably supported by the magnetic bearings (radial magnetic bearings MB1 and axial magnetic bearings MB2) via the rotary shaft 5, and further, if the drive motor MO is activated in this state of support, the cylindrical portion 6 can rotate about its rotational axis integrally with the rotary shaft 5. In short, in the vacuum pump P1 of the present embodiment, Figure 1 In the vacuum pump P1 of the present embodiment, the rotary shaft 5 and the magnetic bearings function as a support mechanism that rotatably supports the cylindrical portion 6, and the drive motor MO functions as a drive mechanism that rotationally drives the cylindrical portion 6.

[0065] Further, in the vacuum pump P1 of the present embodiment, Figure 1 The vacuum pump P1 of the present embodiment has a plurality of exhaust stages PT that exhaust gas molecules between the suction port 2 and the exhaust port 3.

[0066] Further, in the vacuum pump P1 of the present embodiment, Figure 1 In the vacuum pump P1 of the present embodiment, a screw groove pump stage PS is provided at the downstream side of the plurality of exhaust stages PT, specifically, between the exhaust stage PT (PTn) that is the lowermost stage among the plurality of exhaust stages PT and the exhaust port 3.

[0067] The uppermost exhaust stage PT (PT1) among the plurality of exhaust stages PT further has a particle transport portion PN that transports particles in the direction of exhaust of gas molecules.

[0068] <Exhaust Stage>

[0069] Figure 1 The plurality of exhaust stages PT function as the plurality of exhaust stages PT at the position upstream of the substantially middle portion of the cylindrical portion 6. Hereinafter, the plurality of exhaust stages PT will be described in detail.

[0070] A plurality of rotating vanes 7 that rotate integrally with the cylindrical portion 6 are provided at the outer circumferential surface of the cylindrical portion 6 at the position upstream of the substantially middle portion of the cylindrical portion 6. These rotating vanes 7 are radially arranged at a predetermined interval with the center axis of the cylindrical portion 6 (specifically, the axis of the rotary shaft 5) or the axis of the housing 1 (hereinafter referred to as "vacuum pump axis") as the center in each exhaust stage PT (PT1, PT2,..., PTn).

[0071] On the other hand, a plurality of stationary vanes 8 are provided on the inner peripheral side of the pump housing 1A, and these stationary vanes 8 are also radially arranged at a predetermined interval with the center of the vacuum pump shaft as the center in each exhaust section PT (PT1, PT2,..., PTn) like the rotary vanes 7.

[0072] That is, Figure 1 Each exhaust section PT (PT1, PT2,..., PTn) in the vacuum pump P1 is provided with a plurality of rotary vanes 7 and stationary vanes 8 radially arranged at a predetermined interval in each exhaust section PT (PT1, PT2,..., PTn), thereby forming a gas exhaust structure that exhausts gas molecules.

[0073] Each rotary vane 7 is a vane-shaped cut product cut out by cutting processing in such a manner as to be integrated with the outer diameter processed portion of the cylindrical portion 6, and is inclined at an angle most suitable for the exhaust of gas molecules. Each stationary vane 8 is also inclined at an angle most suitable for the exhaust of gas molecules.

[0074] "Explanation of Exhaust Action Based on Multiple Exhaust Sections"

[0075] In the plurality of exhaust sections PT configured by the above structure, in the uppermost exhaust section PT (PT1), the plurality of rotary vanes 7 rotate at high speed in conjunction with the rotation of the rotary shaft 5 and the cylindrical portion 6 by the activation of the drive motor MO, and the inclined surface of the rotary vane 7 facing the front and lower side in the rotation direction (the direction from the suction port 2 toward the exhaust port 3, hereinafter referred to as downward) imparts a momentum in the tangential direction and downward to the gas molecules that have entered from the suction port 2. The gas molecules having the momentum in the downward direction are guided to the next exhaust section PT (PT2) by the downward inclined surface of the stationary vane 8 provided in the opposite direction to the rotation direction of the rotary vane 7. In addition, in the next exhaust section PT (PT2) and the exhaust sections PT thereafter, like the uppermost exhaust section PT (PT1), the rotary vanes 7 rotate, and the momentum imparting action to the gas molecules based on the aforementioned rotary vanes 7 and the guiding action of the gas molecules based on the stationary vanes 8 are performed, whereby the gas molecules in the vicinity of the suction port 2 are exhausted in such a manner as to sequentially move toward the downstream of the cylindrical portion 6.

[0076] "Detail Explanation of Thread Groove Pump Section"

[0077] In the vacuum pump P1 of the above structure, Figure 1 The thread groove pump section PS is configured to function as a pump section downstream of the substantially middle of the cylindrical portion 6. Hereinafter, the thread groove pump section PS will be described in detail.

[0078] The thread groove pump section PS is, on the outer peripheral side of the cylindrical portion 6 (specifically, the outer peripheral side of the portion of the cylindrical portion 6 that is downstream of the approximately middle portion of the cylindrical portion 6), provided with a thread groove exhaust portion stator 9 as a mechanism that forms a thread groove exhaust flow path R, the thread groove exhaust portion stator 9 being mounted as a fixed member on the inner peripheral side of the housing 1.

[0079] The thread groove exhaust portion stator 9 is a fixed member that is configured in a cylindrical shape with its inner peripheral surface facing the outer peripheral surface of the cylindrical portion 6, and is configured so as to surround the portion of the cylindrical portion 6 that is downstream of the approximately middle portion of the cylindrical portion 6.

[0080] Furthermore, the portion of the cylindrical portion 6 that is downstream of the approximately middle portion of the cylindrical portion 6 is a portion that rotates as a rotating member of the thread groove exhaust portion PS, and is inserted / housed inside the thread groove exhaust portion stator 9 via a prescribed gap.

[0081] A thread groove 91 that is tapered so as to decrease in depth toward the lower side is formed in the inner peripheral portion of the thread groove exhaust portion stator 9. This thread groove 91 is spirally engraved from the upper end to the lower end of the thread groove exhaust portion stator 9.

[0082] With the thread groove exhaust portion stator 9 provided with the aforementioned thread groove 91, a thread groove exhaust flow path R for gas exhaust is formed on the outer peripheral side of the cylindrical portion 6. In addition, although not shown, it is also possible to form the aforementioned thread groove 91 on the outer peripheral surface of the cylindrical portion 6 so as to provide the aforementioned thread groove exhaust flow path R.

[0083] In the thread groove exhaust portion PS, in order to transport gas while compressing it by means of the drag effect of the thread groove 91 and the outer peripheral surface of the cylindrical portion 6, the depth of the thread groove 91 is set so as to be deepest at the upstream inlet side (flow path opening end near the suction port 2) of the thread groove exhaust flow path R, and shallowest at the downstream outlet side (flow path opening end near the exhaust port 3).

[0084] The inlet (upstream opening end) of the thread groove exhaust flow path R opens into the gap (hereinafter referred to as the "final gap GE") between the fixed vane 8E that constitutes the lowermost stage and the thread groove exhaust portion stator 9 of the exhaust stage PTn. Furthermore, the outlet (downstream opening end) of this thread groove exhaust flow path R is connected to the exhaust port 3 via the in-pump exhaust port side flow path S.

[0085] The in-pump exhaust port side flow path S is formed from the outlet of the thread groove exhaust flow path R to the exhaust port 3 by providing a prescribed gap (gap in the form of a gap between the lower end portion of the cylindrical portion 6, the thread groove exhaust portion stator 9, and the inner bottom portion of the pump base 1B Figure 1 In the vacuum pump P1 of FIG. 1, the gap in the form of a gap around the lower portion of the outer periphery of the stator column 4) between the lower end portion of the cylindrical portion 6, the thread groove exhaust portion stator 9, and the inner bottom portion of the pump base 1B.

[0086] Explanation of Exhaust Action of Thread Groove Exhaust Port

[0087] Gas molecules that have reached the final gap GE by being transported through the exhaust action of the multiple exhaust sections PT described above move to the threaded groove exhaust flow path R. The moving gas molecules are dragged by the rotation of the cylindrical section 6, being compressed from a transitional flow into a viscous flow while moving towards the pump's internal exhaust port side flow path S. After reaching the pump's internal exhaust port side flow path S, the gas molecules flow into the exhaust port 3 and are exhausted outside the housing 1 by a supplementary pump (not shown).

[0088] Explanation of the Particle Transport Unit

[0089] Figure 2 (a) Viewed from the outer circumferential side of the cylindrical section Figure 1 A diagram illustrating the state of the uppermost exhaust section (including the particle delivery section) in a vacuum pump. Figure 2 (b) is Figure 2 (a) View from direction A, Figure 2 (c) is Figure 2 (a) View from direction B.

[0090] If reference Figure 2 (a) The particle transport section PN is configured such that the height of the upstream end 7A of at least a portion of the rotating blades 7 (71, 74) of the uppermost exhaust section PT (PT1) is increased or decreased, thereby making the uppermost exhaust section PT (PT1) as a whole a step structure with different heights of the upstream end 7A, so that particles can be transported in the exhaust direction of gas molecules.

[0091] exist Figure 2 In example (a), a structure is shown in which the upstream ends 7A of the two rotating blades 71 and 74 located on either side of the two rotating blades 72 and 73 are higher than the upstream ends 7A of the other rotating blades 72, 73 and 75, but this is not a limitation. The number of rotating blades with higher upstream ends 7A and the number of rotating blades located therebetween can be increased or decreased as needed, and the rotating blade with higher upstream ends 7A can also be a single blade.

[0092] For ease of explanation, the portion of the multiple rotating blades 7 that make up the uppermost exhaust section PT (PT1) will be referred to as the "blade height NB" due to the aforementioned step structure.

[0093] If reference Figure 22It is assumed that the particulate process by-products generated incidentally in the chemical process in the vacuum chamber CH float / diffuse in the vacuum chamber CH and fall toward the suction port 2 of the vacuum pump PI due to the self-weight and the transport effect based on the gas molecules. Furthermore, it is assumed that the deposits adhering to the inner wall surface of the vacuum chamber CH and the deposits adhering to the pressure regulating valve BL are peeled off due to vibration or the like and fall toward the suction port 2 of the vacuum pump PI due to the self-weight.

[0094] If reference is made to Figure 2 (a), the particles Pa that have arrived at the suction port 2 by the aforementioned falling further fall from the suction port 2 and first enter the particle transport portion PN and collide with the blade high portion NB.

[0095] The plurality of particles that collide with the blade high portion NB can be roughly classified into exhaust direction reflection particles and backflow particles if the traveling directions of the particles after the collision are distinguished. The exhaust direction reflection particles are particles that are reflected in the gas molecule exhaust direction by collision with the inclined surface FS (hereinafter referred to as "blade high portion front inclined surface FS") of the blade high portion NB located on the front side of the traveling direction based on the rotation of the blade high portion NB. The backflow particles are particles that are bounced back toward the suction port 2.

[0096] In the uppermost exhaust stage PT (PT1), the particle transport portion PN is provided, whereby the proportion of the exhaust direction reflection particles increases and the proportion of the backflow particles decreases. The reason is as described in the "Investigation" described below.

[0097] "Investigation"

[0098] Figure 3 is a diagram of the collision possible region of the particles that fall in a vacuum pump that does not have a particle transport portion, Figure 4 is a diagram of the collision possible region of the particles that fall in a vacuum pump that has a particle transport portion Figure 1 of the present application.

[0099] If reference is made to Figure 3 , in the case of a vacuum pump that does not have a particle transport portion, the collision possible region Zpl of the particles in the diameter D portion (see Figure 2 (c)) of the uppermost exhaust stage P (PT1) is obtained by the following formula (3).

[0100] Zpl = {(πD / N-T) Vp} / (Vr)... formula (3)

[0101] N: the number of pieces of the rotating blade 7 that constitutes the uppermost exhaust stage

[0102] D: the size of the diameter D portion (see Figure 2 (c))

[0103] T: The axial right-angle thickness of the diameter D portion of the rotating blade 7 constituting the uppermost exhaust section (refer to...) Figure 2 (c)

[0104] Vp: The falling velocity of the particle

[0105] Vr: Rotational speed (circumferential speed) of the diameter D section of the rotating blade 7.

[0106] If reference Figure 4 Then the height (prominence height) Zp2 of the aforementioned step structure is specified based on the following formula (4).

[0107] The following formula (4) is for the general Figure 2 (a) The two rotating blades 72 and 73 are as follows Figure 3 The formula is applied to consider n rotating blades 7, 7... and the upstream end 7A of the rotating blades 71, 74 located on both sides of the n rotating blades 7, 7 is higher than the upstream end of the other rotating blades (other than 71, 74) due to the step difference structure.

[0108] Zp2 = {(πD / n / N)Vp} / (Vr) …Equation (4)

[0109] n: The number of rotating blades located between the upstream high rotating blades 71 and 74.

[0110] D: Dimension of diameter D (refer to...) Figure 2 (c)

[0111] N: The number of rotating blades 7 that make up the uppermost exhaust section.

[0112] Vp: The falling velocity of particle Pa

[0113] Vr: Rotational speed (circumferential speed) of the diameter D section of the rotating blade 7.

[0114] exist Figure 2 In section D of diameter (c), if the step difference between the n rotating blades 7 and the rotating blades 71, 74 located on both sides of it is as follows: Figure 4 If set to Zp2 or higher, it will fall into the space between the rotating blades marked 71 and 74 in the attached diagram (in Figure 2 The particles (equivalent to L2) do not collide with the n rotating blades 7, but collide with the front surface of the rotating blade 74. Furthermore, the collision region of the particles towards the front surface of the rotating blade 74 is defined by Zp3, which will be described later based on the following equation (5).

[0115] In this study, it was found that there is a rotating blade in the uppermost exhaust section PT (PT1) with a height Zp2 above the blade height NB at the upstream end.

[0116] In this case, the diameter D portion (refer to Figure 2 (c) ) of the exhaust stage PT (PT1) of the uppermost stage is considered, and the collision possible region Zp3 (refer to Figure 4 ) of the particles is specified based on the following equation (5).

[0117] Zp3 = {πD(n+1) / N-T}Vp / (Vr)... Equation (5)

[0118] N: the number of pieces of the rotating blade 7 constituting the exhaust stage of the uppermost stage

[0119] D: the size of the diameter D portion Figure 2 (c) refer to

[0120] T: the axial right angle thickness of the diameter D portion of the rotating blade 7 constituting the exhaust stage of the uppermost stage (refer to Figure 2 (c) )

[0121] Vp: the falling speed of the particles

[0122] Vr: the rotating speed (circumferential speed) of the diameter D portion of the rotating blade 7

[0123] n: the number of pieces of the rotating blade between the rotating blades 71, 74 at the upstream end height.

[0124] If refer to Figure 4 , the relative speed Vc of the particles observed from the rotating blade 7 is obtained from the rotating speed Vr of the rotating blade 7 of the diameter D portion (refer to Figure 2 ) and the falling speed Vp of the particles. In Figure 4 , if the interval of the rotating blades 7 (71, 74) at the upstream end height or the interval is set as the blade interval L', the particles (the particles capable of being shot (fall) to the most downstream side within the blade interval L') shot from the A point of the Figure 4 fall within the blade interval L' to the B' point on the extension line of the tip end of the rotating blade 7 (74). The falling distance from the upper end surface 7A of the rotating blade 7 (74) to the B' point is Zp3 obtained from the above equation (5). In the vacuum pump (corresponding to the vacuum pump of the present application) of the Figure 1 having the blade height portion NB, the blade surface without the chamfer or the like is present within this Zp3, and thus the particles falling to the B' point can further fall and finally collide with the C' point in the front surface of the rotating blade 7 (74), specifically with the downwardly inclined surface of the rotating blade 7 (74).

[0125] As is apparent from the above description, in the Figure 1The falling distance Zp4 of the particle from the upper end surface 7A of the rotating blade 7 (74) to the point C' in the vacuum pump P1 becomes a collision possible region of the particle, and the collision possible region (falling distance Zp4) is larger than the collision possible region Zp3 obtained from the above equation (5).

[0126] In short, if the height of the step based on the step structure described above is set to Zp2, the particle that has entered from the point A collides with the point B, but if such a step is set to Zp2 or more, the particle does not collide with the n rotating blades 7 but collides with the front surface of the rotating blade 7 (74) (for example, the point C' in the downwardly inclined surface of the rotating blade 7 (74)). Figure 4

[0127] Here, the above equation (3) and the above equation (5) are compared. At this time, if the thickness T of the rotating blade 7 in the above equation (3) and the above equation (5) is ignored for the sake of simplicity, in the case where the step structure in which the height of the step is Zp2 or more is adopted as described above, that is, in the case of the above equation (5), the collision possible region of the particle Pa is enlarged by (n + 1) times compared to the case of the above equation (3), and therefore the proportion of the particles that are reflected in the exhaust direction increases and the proportion of the particles that are backstreaming decreases. The reason for this is, in short, because if the collision possible region of the particle is enlarged, the probability of collision with the inclined surface of the rotating blade 7 and the blade NB that is inclined toward the exhaust direction of the gas molecules and is reflected in the exhaust direction of the gas molecules is more advantageous than the probability of collision with the surface that is more likely to be backstreamed toward the gas suction port 2.

[0128] "Explanation of a structure for correcting the unbalance of the entire rotating body"

[0129] In the vacuum pump P1, Figure 1 The rotating body R is constituted by a plurality of rotating blades 7 and a particle transport portion PN, a cylindrical portion 6 that supports the plurality of rotating blades 7, and is provided with a blade high portion NB in a point-symmetrical manner with the rotation axis 5 of the rotating body R as a point-symmetrical axis, and therefore the balance of the entire rotating body R is obtained. That is, the entire rotating body R is rotationally symmetrical with the rotation axis 5 as the center.

[0130] However, the effect of the particle transport portion PN, that is, the decrease in the proportion of the backstreaming particles described above, is sufficiently exerted even when the rotating blade 7 (74) (hereinafter referred to as "high blade 7 (74)") of which the height of the upstream end 7A is high due to the step structure described above is one blade. However, in this case, the entire rotating body R cannot be rotationally symmetrical with the rotation axis 5 as the center due to the presence of the high blade 7 (74) (specifically, the mass of the blade high portion NB), and unbalance is generated with respect to the entire rotating body R. Furthermore, in the case where a plurality of such high blades are present, unbalance of the entire rotating body R is generated as long as the plurality of high blades are not point-symmetrical with the rotation axis 5 of the rotating body R as a point-symmetrical axis. ​

[0131] Figure 5 This is a top view of the solid of revolution before the imbalance is corrected. Figure 6 This diagram illustrates the basic thinking behind correcting the imbalance of a rotating body as a whole.

[0132] Figure 6 In the attached figures, reference numeral "M" indicates the mass of the rotating body R as a whole, excluding the blade height NB; reference numeral "m" indicates the mass of the blade height NB; reference numeral "O" indicates the center of rotation of the rotating body R; reference numeral "G" indicates the center of gravity of the rotating body R including the blade height NB; and reference numeral "e" indicates the distance from this center of gravity to the center of rotation of the aforementioned rotating body. Furthermore, reference numeral "r" indicates the distance from the center of rotation O of the aforementioned rotating body to the center of gravity of the individual blade height NB; reference numeral "ω" indicates the angular velocity of rotation of the rotating body R; and reference numeral "F" indicates the centrifugal force generated based on the increase in mass of the blade height NB. This centrifugal force F can be expressed as m∙r∙ω. 2 express.

[0133] The basic approach to correcting the overall imbalance of the rotating body R is to consider the aforementioned centrifugal force F (=m∙r∙ω). 2 The balance of the rotating body R is set.

[0134] exist Figure 1 In the case of an overall imbalance of the rotating body R in the vacuum pump P1, considering the aforementioned centrifugal force F, the first to seventh imbalance correction structures described later can be adopted. Furthermore, the first to seventh imbalance correction structures can be used independently or in combination.

[0135] Explanation of the First Unbalanced Correction Structure

[0136] The first imbalance correction structure is to remove a portion of the high blade 7 (74) or the nearby rotating blades (73, 75) to correct the aforementioned imbalance.

[0137] The removal of the aforementioned part, such as Figure 7 , Figure 8 As shown, a fixed amount can be removed from the back side 7B of the rotation direction, which contributes less to the exhaust of gas molecules, in the entire blade surface of the high blade 7 (74). In addition, a fixed amount can also be removed from the back side of the rotating blade close to the high blade 7 (74).

[0138] exist Figure 7 , Figure 8 In the example, the back surface 7B is removed in a way that forms an arc surface, but this is not a limitation. Furthermore, the amount and location of removal of the back surface 7B can be appropriately changed as needed. The removal range of the back surface 7B can be as follows: Figure 8 The area shown includes the blade height NB, and can also be as follows:Figure 7 The high blade 7 (74) is shown as not including the blade height NB.

[0139] The removal of the aforementioned portion can be such that, as shown in Figure 9 the downstream end edge 7C of the high blade 7 (74) is removed by a prescribed amount. Further, it is also possible to cut the downstream end edge 7C of the rotating blade near the high blade 7 (74) by a prescribed amount.

[0140] In the example of Figure 9 , the downstream end edge 7C of the high blade 7 (74) is removed by the length of the blade height NB, but the amount of removal can be changed as appropriate as needed.

[0141] The removal of the aforementioned portion can be such that, as shown in Figure 10 a hole H is provided in the high blade 7 (74). Further, it is also possible to provide a hole in the rotating blade near the high blade 7 (74).

[0142] In the example of Figure 10 , a plurality of holes H (specifically, non-through holes) are formed at prescribed intervals along the direction from the upstream end 7A to the downstream end 7C of the rotating blade 7 (74), but are not limited thereto. For example, the holes H can be provided a plurality of times in the radial direction of the high blade (74) (the same direction as the radial direction of the cylindrical portion 6. The same hereinafter). The number of holes H, the formation position can be changed as appropriate as needed. The same is true when a hole is provided in the rotating blade near the high blade 7 (74).

[0143] The removal of the aforementioned portion can also be such that, as shown in Figure 11 a groove Gr is formed in the high blade 7 (74). Further, it is also possible to form a groove in the rotating blade near the high blade 7 (74).

[0144] In the example of Figure 11 , a groove Gr of an elongated shape in the direction from the upstream end 7A to the downstream end edge 7C of the high blade 7 (74) is formed on the back side of the high blade 7 (74), but is not limited thereto. The shape, length, number of the groove Gr can be changed as appropriate as needed.

[0145] For example, the groove Gr can also be formed in a horizontal long shape in the radial direction of the rotating blade 7 (74), and such a horizontal long shape groove and the aforementioned vertical long shape groove Gr can be used in combination. The same is true when a groove is provided in the rotating blade near the high blade 7 (74).

[0146] Further, although not shown, the removal of the aforementioned portion can be such that the radial length of the high blade 7 (74) or the rotating blade near it is made shorter than the radial length of the standard rotating blade 7 other than them. In this case, the length made shorter can be changed as appropriate as needed.

[0147] Further, the removal of a part of the foregoing can also be as Figure 12 and Figure 13 is to remove the upstream end 7A of the rotating blade 7 approaching the high blade 7 (74) by a predetermined amount.

[0148] Figure 13 and Figure 5 the reference sign "H2" in the drawing shows the height of the rotating blade 7 (74) provided with the particle delivery part PN, Figure 13 the reference sign "H3" in the drawing shows the height of the rotating blade 7 (72, 73, 75) approaching the rotating blade 7 (74), Figure 13 and Figure 5 the reference sign "H1" in the drawing shows the height of the standard rotating blade other than them, respectively.

[0149] From the comparison of the foregoing heights (H3 < H1 < H2), Figure 13 and Figure 15 it is known that in the examples of Figure 12 and Figure 13 the upstream end 7A of the rotating blade 7 approaching the high blade 7 (74) on the left and right is removed by a predetermined amount, but is not limited to this example. The number of rotating blades 7 whose upstream end 7A is cut and the length of the cut can be appropriately changed as needed.

[0150] "Explanation of the Second Unbalance Correction Structure (Counterbalance)"

[0151] Figure 14 is an explanatory view of the second unbalance correction structure (counterbalance).

[0152] In the second unbalance correction structure, as shown in Figure 14 , a predetermined mass is added to the rotating blade which is the rotating blade in point symmetry with the high blade 7 (74) with the rotation axis 5 of the rotating body R as the point symmetry axis, that is, the rotating blade 7 (n) located on the opposite side of the high blade 7 (74) with respect to the rotation center or the rotating blade 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) approaching the same, thereby correcting the foregoing unbalance.

[0153] The foregoing predetermined mass is a mass for generating a centrifugal force (for example, a centrifugal force of the same size as F but in the opposite direction) that cancels the foregoing centrifugal force F. Hereinafter, it is referred to as "counterbalancing mass". In addition, in Figure 14 , the rotating blade 7 to which the counterbalancing mass is added is marked with the reference sign (+).

[0154] Hereinafter, for the sake of convenience of explanation, the rotating blade 7 (n) located on the opposite side of the high blade 7 (74) with respect to the center of rotation will be referred to as a "symmetrical blade", and the plurality of rotating blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) located on both sides of the symmetrical blade 7 (n) will be referred to as "symmetrical approach blades".

[0155] If reference is made to Figure 14 , because the mass m of the blade high portion NB exists in the high blade 7 (74), the corresponding mass is added to the symmetrical blade 7 (n), or the corresponding mass distribution is added to the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2), or the aforementioned imbalance can also be corrected by distributing the corresponding mass to both the symmetrical blade 7 (n) and the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2).

[0156] As for the specific structure of adding the aforementioned corresponding mass, illustration is omitted, but the following structures can be used, and these structures can be used in combination: as a first structure example, a structure in which the downstream end edge 7C of the symmetrical blade 7 (n) or the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) is elongated than the rotating blades 7 other than them, as a second structure example, a structure in which the radial length of the symmetrical blade 7 (n) or the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) is set to be longer than the rotating blades 7 other than them, and as a third structure example, a structure in which the thickness of the symmetrical blade 7 (n) or the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) is increased than the rotating blades 7 other than them.

[0157] As shown in Figure 14 , in the case where the corresponding mass distribution is added to the symmetrical blade 7 (n) and the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2), as shown in, for example, Figure 15 , a structure in which the height of the upstream end 7A of the symmetrical blade 7 (n) and the symmetrical approach blades 7 (n-2), 7 (n-1), 7 (n+1), 7 (n+2) is increased or decreased in a range not exceeding the height H2 of the high blade 7 (74) as shown in, for example, the following equation (6) or the following equation (7) can be adopted.

[0158] In addition, for the sake of convenience of explanation, the following equation (6) compares the blade height using the reference numerals added to each blade, and the following equation (7) compares the blade height using the reference numerals showing the height of each blade, and both equations express the same meaning.

[0159] 7(75) < { 7( n+2 ) = 7( n-2 )}, {7( n+1 ) = 7( n-1 )}, 7( n ) < 7(74) … Equation (6)

[0160] H1 < { h1 = h5},{ h2 = h4}, h3 < H2 … Equation (7).

[0161] In Figure 15 , as a specific example of the above Equation (7), 7(75) < { 7( n+2 ) = 7( n-2 )} < {7( n+1 ) = 7( n-1 )} < 7( 74 ) is shown, and as a specific example of the above Equation (6), H1 < { h1 = h5} < { h2 = h4} < H2 is shown, but is not limited thereto. The size relationship of h1(=h5) and h2(=h4) and h3, or the size relationship of { 7( n+2 ) = 7( n-2 )} and {7( n+1 ) = 7( n-1 )} and 7( n ) is arbitrary, and can be changed as appropriate according to necessity.

[0162] Explanation of the Third Unbalance Correction Structure

[0163] The third unbalance correction structure is as shown in Figure 16 or Figure 17 The arrangement interval of at least two or more rotating blades on the same side as the high blade 7(74) is set to be larger than the arrangement interval of the rotating blades 7 other than them, thereby correcting the aforementioned unbalance.

[0164] Referring to Figure 5 , in the rotating body R before using the third unbalance correction structure, the arrangement interval of all the rotating blades 7 including the high blade 7(74) is set to Pi1.

[0165] On the other hand, in the example of Figure 16 , the arrangement interval Pi3 of the high blade 7(74) and the rotating blade 7(75) on one side thereof is set to be larger than the arrangement interval Pi2 of the rotating blades 7 other than them, thereby correcting the aforementioned unbalance.

[0166] Further, in the example of Figure 17 , the arrangement interval Pi5 of the high blade 7(74) and the rotating blades 7(73, 75) on both sides thereof is set to be larger than the arrangement interval Pi4 of the rotating blades 7 other than them, thereby correcting the aforementioned unbalance.

[0167] Explanation of the Fourth Unbalance Correction Structure (Counterbalance)

[0168] The fourth unbalance correction structure is as shown inFigure 18 As shown, the arrangement interval of at least two or more of the rotating vanes located on the opposite side of the high vane 7(74) is set narrower than the arrangement interval of the rotating vanes other than them, thereby correcting the aforementioned imbalance. That is, the fourth imbalance correction structure is such that the arrangement density of the rotating vanes on the opposite side of the high vane 7(74) is large compared to the vicinity of the high vane 7(74), thereby functioning as a counterbalance with respect to the high vane 7(74).

[0169] In the example shown in FIG. 6, the arrangement interval of the seven rotating vanes (from 7(n+3) to 7(n-3)) located on the opposite side of the high vane 7(74) is set narrower than the arrangement interval of the rotating vanes other than them (for example, 7(73), 7(76)), but is not limited to this example. The number of the rotating vanes having the narrower arrangement interval can be appropriately changed as needed. Figure 19

[0170] The first to fourth imbalance correction structures described above all correct the imbalance of the entire rotating body R in the uppermost exhaust section PT(PT1), but are not limited thereto. The structure of removing a part of the predetermined rotating vane as in the first imbalance correction structure, the structure of adding the corresponding mass to the predetermined rotating vane as in the second imbalance correction structure, and the structure of setting the arrangement interval of the rotating vane as in the third imbalance correction structure can also be used in the exhaust sections PT(PT1), PT(PT2),... PT(PTn) other than the uppermost exhaust section PT(PT1).

[0171]

[0172]

[0173] The sixth imbalance correction structure is shown in FIG. 6, for example. In the example shown in FIG. 6, the recess 61 is provided on the outer peripheral surface (the surface on which the rotating vane 7 is not provided) of the cylindrical portion 6, thereby correcting the aforementioned imbalance. Figure 20 Alternatively, as shown in FIG. 7, the protrusion 62 is provided on the outer peripheral surface (the surface on which the rotating vane 7 is not provided) of the cylindrical portion 6, thereby correcting the aforementioned imbalance. Figure 19 In the example shown in FIG. 6, the aforementioned recess 61 is provided in the lower portion of the uppermost exhaust section PT(PT1), specifically, slightly below the high vane 7(74), and in the example shown in FIG. 7, the aforementioned protrusion 62 is provided in the lower portion of the uppermost exhaust section PT(PT1), specifically, slightly below the symmetric vane 7(n).

[0174] Figure 20 In the example shown in FIG. 6, the aforementioned recess 61 is provided in the lower portion of the uppermost exhaust section PT(PT1), specifically, slightly below the high vane 7(74), and in the example shown in FIG. 7, the aforementioned protrusion 62 is provided in the lower portion of the uppermost exhaust section PT(PT1), specifically, slightly below the symmetric vane 7(n). Figure 19 The position, size, and shape of the aforementioned recess 61 and the aforementioned protrusion 62 are not limited to those shown in FIGS. 6 and 7.

[0175] Figure 20 Figure 21 ​​​​​​Examples can be modified as needed. For example, the recess 61 and the protrusion 62 can also be provided on the lower part of the exhaust section other than the uppermost exhaust section PT (PT1), for example, on the outer peripheral surface of the cylindrical part 6 slightly below the lower part of the second or third exhaust section PT (PT2) or PT (PT3) from the top (specifically, the rotating blades 7 constituting these exhaust sections PT (PT2) or PT (PT3)).

[0176] Explanation of the Seventh Unbalanced Correction Structure

[0177] The seventh unbalanced correction structure, such as Figure 21 As shown, a portion of the washer WS used to fasten the rotating body R and the rotating shaft 5 of the rotating body R is scraped off, thereby correcting the aforementioned imbalance.

[0178] exist Figure 21 In the example, the washer WS has a shaft insertion hole WS1 for a rotating shaft 5 at its center, and multiple threaded insertion holes WS2 are provided around the shaft insertion hole WS1, forming a ring shape as a whole. Furthermore, in this... ​ In the example, the root portion near the high blade 7 (74) in the outer periphery of the washer WS is removed as shown by reference numeral CC in the figure, thereby correcting the aforementioned imbalance, but is not limited to this. The specific portion of the washer WS to be removed and to what extent can be adjusted as needed while observing the correction of the overall imbalance of the rotating body R.

[0179] The first to seventh unbalanced correction structures described above can be used individually or in combination.

[0180] The present invention is not limited to the embodiments described above. Techniques for correcting the overall imbalance of the rotating body, such as scraping (removing) the rotating blades, setting holes or slots in the rotating blades, adjusting the length of the rotating blades, adding corresponding mass to the rotating blades, adjusting the arrangement interval of the rotating blades, using which component to correct the imbalance, or selecting the component for correction, can be modified in various ways by those with common sense in the art within the technical concept of the present invention.

[0181] Figure Labels

[0182] 1. Outer shell

[0183] 2. Inlet

[0184] 3. Exhaust port

[0185] 4 stator columns

[0186] 5. Rotation axis

[0187] 6. Cylindrical section

[0188] 61 recess

[0189] 62 protrusion

[0190] 7 rotating blade

[0191] 8 fixed blade

[0192] 9 screw groove exhaust portion stator

[0193] 91 screw groove

[0194] BL pressure adjusting valve

[0195] CH vacuum chamber

[0196] CC cutout of gasket portion

[0197] D diameter of rotating blade

[0198] FS forward inclined surface of blade constituting particle transport portion

[0199] GE final gap

[0200] MB1 radial magnetic bearing

[0201] MB2 axial magnetic bearing

[0202] MO drive motor

[0203] MS chamfered portion

[0204] MC upper portion of chamfered portion

[0205] P1 vacuum pump

[0206] Pa fine particle

[0207] PN particle transport portion

[0208] PS screw groove pump stage

[0209] PT exhaust stage

[0210] PT1 exhaust stage of uppermost stage

[0211] PTn exhaust stage of lowermost stage

[0212] R screw groove exhaust flow path

[0213] S pump-internal exhaust port side flow path

[0214] WS gasket

[0215] WS1 shaft insertion hole

[0216] WS2 screw insertion hole

[0217] Z Previous vacuum pumps.

Claims

1. A vacuum pump, having a plurality of exhaust stages for exhausting gas molecules between a gas suction port and a gas exhaust port, in the plurality of exhaust stages, a particle transport portion is provided, the particle transport portion is configured to increase or decrease the height of at least a portion of the upstream end of a plurality of rotating blades of an exhaust stage constituting an uppermost stage, so that the plurality of rotating blades of which the height of the upstream end is higher than that of other rotating blades due to the step structure of the uppermost stage as a whole become point-symmetrical, and thereby particles are transported in the direction of exhaust of the gas molecules, characterized in that a rotating body composed of the plurality of rotating blades and the particle transport portion, and the cylinder portion supporting the plurality of rotating blades, and the plurality of rotating blades are integrally formed in the cylinder portion, and for the rotating body as a whole, the imbalance generated by the plurality of rotating blades of which the height of the upstream end is higher than that of other rotating blades due to the step structure without point-symmetry with the rotation axis of the rotating body as an axis of point-symmetry is corrected.

2. The vacuum pump of claim 1, wherein, a portion of the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade is removed, and thereby the imbalance is corrected.

3. The vacuum pump of claim 1, wherein, a rotating direction back surface side of the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade is removed by a predetermined amount from the entire blade surface, and thereby the imbalance is corrected.

4. The vacuum pump of claim 1, wherein, a downstream end edge of the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade is removed by a predetermined amount, and thereby the imbalance is corrected.

5. The vacuum pump of claim 1, wherein, a hole is provided in the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade, and thereby the imbalance is corrected.

6. The vacuum pump of claim 1, wherein, a groove is formed in the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade, and thereby the imbalance is corrected.

7. The vacuum pump of claim 1, wherein, a radial length of the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade is set to be shorter than that of other rotating blades other than them, and thereby the imbalance is corrected.

8. The vacuum pump of claim 1, wherein, an upstream end of the rotating blade close to the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure is removed by a predetermined amount, and thereby the imbalance is corrected.

9. The vacuum pump of claim 1, wherein, a mass is added to a rotating blade located on the opposite side with respect to the rotation center of the rotating blade of which the height of the upstream end is higher than that of other rotating blades due to the step structure or a rotating blade close to the rotating blade, and thereby the imbalance is corrected.

10. The vacuum pump of claim 1, wherein, The downstream end edge of the rotating blade on the opposite side with respect to the rotation center of the rotating blade whose upstream end height becomes higher than the other rotating blades due to the step structure of the upstream end of the rotating blade or the rotating blade close to the rotating blade is extended longer than the other rotating blades, thereby correcting the imbalance.

11. The vacuum pump of claim 1, wherein, The radial length of the rotating blade on the opposite side with respect to the rotation center of the rotating blade whose upstream end height becomes higher than the other rotating blades due to the step structure of the upstream end of the rotating blade or the rotating blade close to the rotating blade is set longer than the radial length of the other rotating blades, thereby correcting the imbalance.

12. The vacuum pump of claim 1, wherein, The thickness of the rotating blade on the opposite side with respect to the rotation center of the rotating blade whose upstream end height becomes higher than the other rotating blades due to the step structure of the upstream end of the rotating blade or the rotating blade close to the rotating blade is increased than the other rotating blades, thereby correcting the imbalance.

13. The vacuum pump of claim 1, wherein, The arrangement interval of at least two or more rotating blades on the same side as the rotating blade whose upstream end height becomes higher than the other rotating blades due to the step structure of the upstream end of the rotating blade or the rotating blade close to the rotating blade is set wider than the arrangement interval of the other rotating blades, thereby correcting the imbalance.

14. The vacuum pump of claim 1, wherein, The arrangement interval of at least two or more rotating blades on the opposite side with respect to the rotating blade whose upstream end height becomes higher than the other rotating blades due to the step structure of the upstream end of the rotating blade or the rotating blade close to the rotating blade is set narrower than the arrangement interval of the other rotating blades, thereby correcting the imbalance.

15. The vacuum pump of claim 1, wherein, The imbalance is corrected by the exhaust section other than the uppermost exhaust section.

16. The vacuum pump of claim 1, wherein, A recess or a protrusion is added to the outer peripheral surface of the cylindrical portion, thereby correcting the imbalance.

17. The vacuum pump of claim 1, wherein, A portion of a gasket for fastening the rotating body and the rotation axis of the rotating body is cut, thereby correcting the imbalance.

18. A rotating body of a vacuum pump, The vacuum pump has a plurality of exhaust sections that exhaust gas molecules between a suction port and a discharge port, The particle transport portion is provided in the plurality of exhaust sections, and the particle transport portion is configured to transport particles to the exhaust direction of the gas molecules by increasing or decreasing the height of at least a portion of the upstream end of a plurality of rotating blades that constitute an exhaust section of an uppermost stage so that the plurality of rotating blades as a whole have a step structure in which the height of the upstream end differs. The rotating body is characterized in that The rotating body is configured by the plurality of rotating blades, the particle transport portion, and a cylindrical portion that supports the plurality of rotating blades, and the plurality of rotating blades are integrally formed in the cylindrical portion.

19. A vacuum pump having a plurality of exhaust sections that exhaust gas molecules between a suction port and a discharge port, In the plurality of exhaust stages, a part of the plurality of rotating vanes of the exhaust stage constituting the uppermost stage has a particle transport portion that transports particles in the exhaust direction of the gas molecules, The rotating body is characterized in that The rotating body is constituted of the plurality of rotating vanes, the particle transport portion, and a cylindrical portion that supports the plurality of rotating vanes, and the plurality of rotating vanes are integrally formed in the cylindrical portion, and for the entire rotating body, an imbalance due to the plurality of rotating vanes having the particle transport portion not being point-symmetrical about the rotational axis of the rotating body as an axis of point symmetry is corrected.

20. A vacuum pump, having a plurality of exhaust stages that exhaust gas molecules between a gas suction port and a gas discharge port, In the plurality of exhaust stages, a particle transport portion is provided that, in the plurality of rotating vanes of the exhaust stage constituting the uppermost stage, increases or decreases the height of at least a part of the upstream end so that the entire exhaust stage of the uppermost stage becomes a stepped structure in which the height of the upstream end differs, thereby transporting particles in the exhaust direction of the gas molecules, The rotating body is characterized in that The rotating body is constituted of the plurality of rotating vanes, the particle transport portion, and a cylindrical portion that supports the plurality of rotating vanes, and the plurality of rotating vanes are integrally formed in the cylindrical portion, and for the entire rotating body, an imbalance due to the plurality of rotating vanes having the particle transport portion not being point-symmetrical about the rotational axis of the rotating body as an axis of point symmetry is corrected.

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