US20030017047A1 - Turbo-molecular pump - Google Patents
Turbo-molecular pump Download PDFInfo
- Publication number
- US20030017047A1 US20030017047A1 US10/244,740 US24474002A US2003017047A1 US 20030017047 A1 US20030017047 A1 US 20030017047A1 US 24474002 A US24474002 A US 24474002A US 2003017047 A1 US2003017047 A1 US 2003017047A1
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- United States
- Prior art keywords
- turbo
- rotor
- molecular pump
- stator
- scattering prevention
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/02—Multi-stage pumps
- F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
- F04D19/042—Turbomolecular vacuum pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/52—Casings; Connections of working fluid for axial pumps
- F04D29/522—Casings; Connections of working fluid for axial pumps especially adapted for elastic fluid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/70—Suction grids; Strainers; Dust separation; Cleaning
- F04D29/701—Suction grids; Strainers; Dust separation; Cleaning especially adapted for elastic fluid pumps
Definitions
- the present invention relates to a turbo-molecular pump for evacuating gas with a rotor that rotates at a high speed.
- FIG. 21 of the accompanying drawings shows a conventional turbo-molecular pump.
- the conventional turbo-molecular pump comprises a rotor R and a stator S which are housed in a pump casing 14 .
- the rotor R and the stator S jointly make up a turbine blade pumping section L 1 and a thread groove pumping section L 2 .
- the stator S comprises a base 15 , a stationary cylindrical sleeve 16 vertically mounted centrally on the base 15 , and stationary components of the turbine blade pumping section L 1 and the thread groove pumping section L 2 .
- the rotor R mainly comprises a main shaft 10 inserted coaxially in the stationary cylindrical sleeve 16 , and a rotary cylindrical sleeve 12 mounted on the main shaft 10 and disposed around the stationary cylindrical sleeve 16 .
- a drive motor 18 Between the main shaft 10 and the stationary cylindrical sleeve 16 , there are provided a drive motor 18 , an upper radial magnetic pole 20 disposed above the drive motor 18 , and a lower radial magnetic pole 22 disposed below the drive motor 18 .
- An axial bearing 24 is disposed at a lower portion of the main shaft 10 , and comprises a target disk 24 a mounted on the lower end of the main shaft 10 , and upper and lower electromagnets 24 b provided on the stator side.
- the rotary cylindrical sleeve 12 has rotor blades 30 integrally disposed on an upper outer circumferential portion thereof.
- stator blades 32 disposed axially alternately with the rotor blades 30 .
- the rotor blades 30 and the stator blades 32 jointly make up the turbine blade pumping section L 1 for evacuating gas by way of an interaction between the rotor blades 30 and the stator blades 32 .
- the thread groove pumping section L 2 which is disposed downwardly of the turbine blade pumping section L 1 , includes a thread groove section 34 of the rotary cylindrical sleeve 12 which has thread grooves 34 a defined in an outer circumferential surface thereof and surrounds the stationary cylindrical sleeve 16 .
- the stator S has a spacer 36 disposed around the thread groove section 34 .
- the thread groove pumping section L 2 evacuates gas by way of a dragging action of the thread grooves 34 a in the thread groove section 34 which rotates at a high speed in unison with the rotor R.
- the stator blades 32 have outer edges clamped by either stator blade spacers 38 or the stator blade spacer 38 and the spacer 36 .
- the turbo-molecular pump With the thread groove pumping section L 2 disposed downstream of the turbine blade pumping section L 1 , the turbo-molecular pump is of the wide range type capable of handing a wide range of rates of gas flows.
- the thread grooves 34 a of the thread groove pumping section L 2 are defined in the rotor R.
- the thread grooves of the thread groove pumping section L 2 may be defined in the stator S.
- a turbo-molecular pump comprising a casing having an intake port, a stator fixedly mounted in the casing, a rotor supported in the casing for rotation relatively to the stator, the stator and the rotor serving as at least one of a turbine blade pumping section and a thread groove pumping section for evacuating gas, and a scattering prevention member for preventing fragments of the rotor from being scattered through the intake port.
- the scattering prevention member is effective to prevent those fragments from damaging the chamber in a processing apparatus connected to the intake port or devices and products being processed in the chamber.
- the scattering prevention member may be mounted on a stationary member such as the casing, or the rotor.
- the rotor comprises rotor blades and the stator comprises stator blades, and the scattering prevention member comprises at least part of the rotor blade or the stator blade. Therefore, at least part of the rotor blade or the stator blade has a fragment shield function.
- the scattering prevention member includes at least one protrusion projecting radially inwardly from an inner surface of the intake port. If the rotor is broken, rotor fragments collide with the protrusion, and are prevented from being scattered through the intake port or kinetic energy of the rotor fragments is reduced.
- the scattering prevention member is made of a high-strength material and/or a high-energy absorbing material.
- the high-strength material may be stainless steel, titanium alloy, or the like which is stronger than aluminum.
- the high-energy absorbing material may be made of a relatively soft metal material such as lead, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks, e.g., shaped into a honeycomb structure or an assembly of spherical members.
- the scattering prevention member has a shock absorbing structure.
- the shock absorbing structure is effective to absorb the kinetic energy of rotor fragments which collide with the scattering prevention member for better protection of the chamber in the processing apparatus that is connected to the intake port.
- FIG. 1 is an axial cross-sectional view of a turbo-molecular pump according to a first embodiment of the present invention
- FIG. 2 is a plan view of the turbo-molecular pump shown in FIG. 1;
- FIG. 3 is an axial cross-sectional view of a turbo-molecular pump according to a second embodiment of the present invention.
- FIG. 4 is an axial cross-sectional view of a turbo-molecular pump according to a third embodiment of the present invention.
- FIG. 5 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 4;
- FIG. 6 is an axial cross-sectional view of a turbo-molecular pump according to a fourth embodiment of the present invention.
- FIG. 7 is a plan view of the turbo-molecular pump shown in FIG. 6;
- FIG. 8 is an axial cross-sectional view of a turbo-molecular pump according to a fifth embodiment of the present invention.
- FIG. 9 is an axial cross-sectional view of a turbo-molecular pump according to a sixth embodiment of the present invention.
- FIG. 10 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 9;
- FIG. 11 is a plan view of metal pipes of a shock absorbing member used in the turbo-molecular pump shown in FIG. 9;
- FIG. 12 is an axial cross-sectional view of a turbo-molecular pump according to a seventh embodiment of the present invention.
- FIG. 13 is an axial cross-sectional view of a turbo-molecular pump according to an eighth embodiment of the present invention.
- FIG. 14 is an axial cross-sectional view of a turbo-molecular pump according to a ninth embodiment of the present invention.
- FIG. 15 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 14;
- FIG. 16 is an axial cross-sectional view of a turbo-molecular pump according to a tenth embodiment of the present invention.
- FIG. 17 is an axial cross-sectional view of a turbo-molecular pump according to an eleventh embodiment of the present invention.
- FIG. 18 is a plan view of the turbo-molecular pump shown in FIG. 17;
- FIG. 19 is an axial cross-sectional view of a turbo-molecular pump according to a twelfth embodiment of the present invention.
- FIG. 20 is a plan view of the turbo-molecular pump shown in FIG. 19.
- FIG. 21 is an axial cross-sectional view of a conventional turbo-molecular pump.
- turbo-molecular pump according to embodiments of the present invention will be described below. Like or corresponding parts are denoted by like or corresponding reference characters throughout views. Those parts of turbo-molecular pumps according to the present invention which are identical to those of the conventional turbo-molecular pump shown in FIG. 21 are denoted by identical reference characters, and will not be described in detail below.
- FIGS. 1 and 2 show a turbo-molecular pump according to a first embodiment of the present invention.
- the turbo-molecular pump according to the first embodiment has a protective cover 50 serving as a scattering prevention member mounted on the flange 14 b around the intake port 14 a in the pump casing 14 .
- the protective cover 50 comprises a circular shield 52 disposed centrally in the intake port 14 a in covering relationship to an area directly above the rotary cylindrical sleeve 12 of the rotor R, a ring-shaped rim 56 disposed concentrically with and radially outwardly of the circular shield 52 and having an opening whose size is the same as the size of the intake port 14 a, and a plurality of (three in FIG. 2) support bars 54 extending radially outwardly from the circular shield 52 to connect the circular shield 52 and the rim 56 to each other.
- the protective cover 50 has a step 56 a on the lower surface of the rim 56 which is fitted over the flange 14 b, so that the protective cover 50 is fixed to the pump casing 14 .
- the flange 14 b may have a step, and the protective cover 50 may be fitted in the step and fastened to the flange 14 b by bolts.
- the protective cover 50 may be fitted in the step in the flange 14 b and simply sandwiched between the pump casing 14 and the chamber in the processing apparatus to which the turbo-molecular pump is connected.
- the axially uppermost stator blade 32 a of all the stator blades 32 is made of a material stronger than aluminum, such as stainless steel, titanium alloy, or the like, and the remaining stator blades 32 are made of aluminum.
- the stator blade 32 a also serves as a scattering prevention member.
- the turbo-molecular pump having the above structure, if the rotor R is broken due to corrosion or the like while it is rotating, fragments of the rotary cylindrical sleeve 12 or the rotor blades 30 in the rotor R collide with the shield 52 of the protective cover 50 , thereby losing their kinetic energy toward the intake port 14 a. Therefore, the chamber or the like connected to the intake port 14 a of the pump casing 14 is prevented from being damaged, or the degree of damage of the chamber or the like is reduced.
- the shield 52 covers only the rotary cylindrical sleeve 12 . However, the shield 52 may cover not only the rotary cylindrical sleeve 12 , but also part of the rotor blades 30 .
- stator blade 32 a of the stator blades 32 is made of a material stronger than aluminum, the stator blade 32 a is not broken or is broken to a lesser degree when it is hit by fragments of the rotor blades 30 made of aluminum.
- the stator blade 32 a thus effectively serves as a scattering prevention member for preventing fragments from being scattered through the intake port 14 a.
- stator blade 32 a of the stator blades 32 is made of a high-strength material.
- any other arbitrary stator blades 32 e.g., first- and fourth-stage stator blades 32 may be made of a high-strength material. This holds true for other embodiments of the present invention.
- the protective cover 50 is provided as a scattering prevention member, and also the uppermost stator blade 32 a of the stator blades 32 is made of a material stronger than aluminum as a scattering prevention member.
- the uppermost stator blade 32 a may be made of a material stronger than aluminum.
- the turbo-molecular pump in other embodiments described later may have the same structure as the turbo-molecular pump in the first embodiment.
- FIG. 3 shows a turbo-molecular pump according to a second embodiment of the present invention.
- the circular shield 52 of the protective cover 50 according to the first embodiment is replaced with a substantially cylindrical shield 58 .
- the substantially cylindrical shield 58 has a substantially lower half disposed in a recess 13 defined centrally in the rotary cylindrical sleeve 12 .
- Other details of the turbo-molecular pump according to the second embodiment are identical to those of the turbo-molecular pump according to the first embodiment.
- the gap between the shield 58 and the rotor R is reduced to lower the possibility of fragments to be scattered around for better protection of the chamber to which the turbo-molecular pump is connected.
- the shield 58 also performs an attitude maintaining function to keep the rotor R in its proper attitude when the rotor R suffers abnormal rotation. Any unwanted contact between the rotor R and the stator W can therefore be minimized to reduce the possibility of fragment production.
- FIGS. 4 and 5 shows a turbo-molecular pump according to a third embodiment of the present invention.
- the turbo-molecular pump includes a scattering prevention member having a shock absorbing structure.
- the protective cover 50 as a scattering prevention member has a substantially circular shield 70 disposed centrally therein and having a shank 70 a projecting downwardly, and a shock absorbing member 74 comprising metal pipes 72 wound in two coil-like layers around the shank 70 a.
- the shock absorbing member 74 is surrounded by a cup-shaped cover 76 which is open upwardly.
- the shield 70 has a peripheral edge fastened to a flange of the cover 76 by bolts 78 .
- the cover 76 is disposed so as to enter the recess 13 defined centrally in the rotary cylindrical sleeve 12 .
- the shock absorbing member 74 may alternatively be made of a relatively soft metal material such as lead, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks, e.g., shaped into a honeycomb structure or an assembly of spherical members.
- the shock absorbing member 74 should preferably be made of a corrosion-resistant material or be treated to provide a corrosion-resistant surface such as a nickel coating.
- FIG. 6 and 7 show a turbo-molecular pump according to a fourth embodiment of the present invention.
- the turbo-molecular pump according to the fourth embodiment differs from the turbo-molecular pump according to the first embodiment in the following:
- a plurality of (three in FIG. 7) protrusions 60 which make up a scattering prevention member together with the protective cover 50 , are disposed at predetermined intervals on an inner surface of the intake port 14 a and project radially inwardly in covering relationship to the outer circumferential edges of the rotor blades 30 of the rotor R. While the protrusions 60 are shown as being disposed on the inner surface of the intake port 14 a, the protrusions 60 may alternatively be disposed on the rim 56 of the protective cover 50 .
- FIG. 8 shows a turbo-molecular pump according to a fifth embodiment of the present invention.
- the turbo-molecular pump according to the fifth embodiment has a scattering prevention member 62 mounted on the upper end of the main shaft 10 of the rotor R in covering relationship to the upper surface of the rotary cylindrical sleeve 12 that faces the intake port 14 a.
- the scattering prevention member 62 is of a cup shape complementary to the recess 13 in the rotary cylindrical sleeve 12 and has a flange 62 a on its upper end which extends along the flat upper surface of the rotary cylindrical sleeve 12 .
- the scattering prevention member 62 has an internally threaded hole defined in a bottom thereof.
- the main shaft 10 has a fixed portion 10 a at the upper end thereof and having an externally threaded surface.
- the scattering prevention member 62 is fastened to the main shaft 10 by the fixed portion 10 a that is threaded into the internally threaded hole in the scattering prevention member 62 .
- the scattering prevention member 62 may alternatively be fastened to the main shaft 10 or the rotary cylindrical sleeve 12 by other fasteners such as bolts.
- the scattering prevention member 62 is mounted on the rotor R, it is not necessary to provide an obstacle which would otherwise extend across the intake port 14 a for installing the scattering prevention member 62 . Therefore, the velocity of the gas that is evacuated by the turbo-molecular pump is not lowered. Furthermore, because the scattering prevention member 62 is disposed in covering relationship to the recess 13 where fragments of the rotor R tend to be scattered, the scattering prevention member 62 is effective to efficiently prevent fragments of the rotor R from being scattered. While the scattering prevention member 62 is disposed in covering relationship to the rotary cylindrical sleeve 12 in the illustrated embodiment, the scattering prevention member 62 may be disposed so as to cover part of the rotor blades 30 .
- FIGS. 9 through 11 show a turbo-molecular pump according to a sixth embodiment of the present invention.
- the turbo-molecular pump according to the sixth embodiment differs from the turbo-molecular pump according to the fifth embodiment in that a shock absorbing structure is added to the scattering prevention member 62 according to the fifth embodiment.
- Other details of the turbo-molecular pump according to the sixth embodiment are identical to those of the turbo-molecular pump according to the fifth embodiment.
- the upwardly open scattering prevention member 62 houses therein a shock absorbing member 82 comprising a pair of vertical stacks of semiannular metal pipes 80 (see FIG. 11) in radially confronting relationship to each other.
- the main shaft 10 has a vertical extension having an externally threaded upper end.
- a nut 84 as a shock absorbing member holder is threaded over the externally threaded upper end of the extension of the main shaft 10 , thus holding the shock absorbing member 82 against removal.
- the nut 84 is fastened to cause the shock absorbing member 82 to press the lower surface of the flange 62 a thereof against the rotary cylindrical sleeve 12 for thereby securing the scattering prevention member 62 .
- the semiannular metal pipes 80 are used to make up the shock absorbing member 82 for the reason of better productivity.
- fully circular metal pipes, annular metal pipes with open gaps, or coil-shaped metal pipes may also be employed.
- the shock absorbing member 82 may alternatively be made of a relatively soft metal material, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks.
- FIG. 12 shows a turbo-molecular pump according to a seventh embodiment of the present invention.
- the turbo-molecular pump according to the seventh embodiment differs from the turbo-molecular pump according to the fifth embodiment in that the cup-shaped scattering prevention member 62 is replaced with a disk-shaped scattering prevention member 64 that is housed in the recess 13 in the rotary cylindrical sleeve 12 .
- Other details of the turbo-molecular pump according to the seventh embodiment are identical to those of the turbo-molecular pump according to the fifth embodiment.
- the rotary cylindrical sleeve 12 has an upper portion 12 a integral with a hub 12 b thereof.
- turbo-molecular pump according to the seventh embodiment is less costly than the turbo-molecular pump according to the fifth embodiment.
- FIG. 13 shows a turbo-molecular pump according to an eighth embodiment of the present invention.
- the turbo-molecular pump according to the eighth embodiment differs from the turbo-molecular pump according to the fifth embodiment in that the cup-shaped scattering prevention member 62 is fastened to the rotary cylindrical sleeve 12 by bolts 66 and also differs therefrom in the following:
- a plurality of (three in the illustrated embodiment) protrusions 60 which make up a scattering prevention member together with the scattering prevention member 62 , are disposed at predetermined intervals on an inner surface of the intake port 14 a and project radially inwardly in covering relationship to the outer circumferential edges of the rotor blades 30 of the rotor R.
- the turbo-molecular pump according to the eighth embodiment, if the rotor R is broken, then fragments of the rotor blades 30 or the rotary cylindrical sleeve 12 collide with not only the scattering prevention member 62 but also the protrusions 60 , thus reducing the kinetic energy of the fragments introduced into the intake port 14 a.
- the scattering prevention member including the protrusions should preferably be made of a high-strength material such as stainless steel, titanium alloy, or the like.
- FIGS. 14 and 15 show a turbo-molecular pump according to a ninth embodiment of the present invention.
- the turbo-molecular pump according to the ninth embodiment differs from the turbo-molecular pump according to the eighth embodiment in that a shock absorbing structure is added to the scattering prevention member 62 fastened to the rotary cylindrical sleeve 12 according to the eighth embodiment.
- Other details of the turbo-molecular pump according to the ninth embodiment are identical to those of the turbo-molecular pump according to the eighth embodiment.
- a support 90 having a shank 90 a is vertically mounted in the recess 13 in the rotary cylindrical sleeve 12 and fastened to the bottom of the recess 13 by bolts 92 .
- the scattering prevention member 62 houses therein a shock absorbing member 96 comprising a pair of vertical stacks of semiannular metal pipes 80 (see FIG. 11) in radially confronting relationship to each other and a plurality of O-rings 94 of fluororubber interposed between the pipes 80 and the scattering prevention member 62 .
- the shank 90 a has a vertical extension having an externally threaded upper end.
- a nut 98 as a shock absorbing member holder is threaded over the externally threaded upper end of the extension of the shank 90 a, thus holding the shock absorbing member 96 against removal.
- the scattering prevention member 62 is limited against its axial movement by the pipes 80 and limited against its radial movement by the O-rings 94 .
- the shock absorbing structure is capable of absorbing shocks due to collision with rotor fragments or stator fragments in both the axial and radial directions.
- annular ledge 12 c is disposed on the upper surface of the rotary cylindrical sleeve 12 around the recess 13
- annular ridge 62 c is disposed on the lower surface of a peripheral edge of the flange 62 a of the scattering prevention member 62 .
- the annular ridge 62 c define a recess 62 b in the lower surface of the flange 62 a.
- FIG. 16 shows a turbo-molecular pump according to a tenth embodiment of the present invention.
- the axially uppermost rotor blade 30 a of all rotor blades 30 is separate from the other rotor blades 30 and is made of a material stronger than aluminum, such as stainless steel, titanium alloy, or the like, and the remaining rotor blades 30 are made of aluminum.
- the uppermost rotor blade 30 a is directly fastened to the main shaft 10 by bolts 100 , and serves as a scattering prevention member.
- the rotor blade 30 a Since the uppermost rotor blade 30 a is made of a material stronger than aluminum, the rotor blade 30 a is not broken or is broken to a lesser degree when it is hit by fragments of the remaining rotor blades 30 made of aluminum. The rotor blade 30 a thus effectively serves as a scattering prevention member for preventing fragments from being scattered through the intake port 14 a.
- FIGS. 17 and 18 show a turbo-molecular pump according to an eleventh embodiment of the present invention.
- the turbo-molecular pump comprises a cylindrical pump casing 114 housing a blade pumping section L 1 and a groove pumping section L 2 which are constituted by a rotor (rotation member) R and a stator (stationary member) S.
- the bottom portion of the pump casing 114 is covered by a base section 115 which is provided with an exhaust port 115 a.
- the top portion of the pump casing 114 is provided with a flange section 114 a for coupling the turbo-molecular pump to an apparatus or a piping to be evacuated.
- the stator S comprises a stator cylinder section 247 provided on the center of the base section 115 , and stationary sections of the blade pumping section L 1 and the groove pumping section L 2 .
- the rotor R comprises a rotor cylinder section 112 attached to a main shaft 110 which is inserted into the stator cylinder section 247 . Between the main shaft 110 and the stator cylinder section 247 , there are provided a drive motor 118 , an upper radial bearing 120 and a lower radial bearing 122 disposed on the upper and lower sides of drive motor 118 , respectively. At the lower part of the main shaft 110 , there is provided an axial bearing 124 having a target disk 124 a at the bottom end of the main shaft 110 and an upper and lower electromagnets; 124 b on the stator side. In this configuration, the rotor R can be rotated at a high speed under a five coordinate active control system.
- Rotor blades (rotor vanes) 130 are provided integrally with the upper external surface of the rotor cylinder section 112 , and on the inside of the pump casing 114 , stator blades (stator vanes) 132 are provided in such a way to alternately interweave with the rotor blades 130 .
- These blade members constitute the blade pumping section L 1 which carries out gas evacuation by cooperative action of the high-speed the rotor blades 130 and the stationary stator blades 132 .
- the groove pumping section L 2 is provided below the blade pumping section L 1 .
- the groove pumping section L 2 comprises a spiral groove section 134 having spiral grooves 134 a on the outer surface of the lower portion of the rotor cylinder section 112 , and the stator S comprises a spiral groove section spacer 251 surrounding the spiral groove section 134 .
- Gas evacuation action of the groove pumping section L 2 is caused by the dragging effect of the spiral grooves 134 a of the spiral groove section 134 .
- the groove pumping section L 2 downstream of the blade pumping section L 1 , a wide-range of the turbo-molecular pump can be constructed so as to enable evacuation over a wide range of gas flow rates using one pumping unit.
- the spiral grooves of the groove pumping section L 2 are provided on the rotor side of the pump structure, but the spiral grooves may be formed on the stator side of the pump structure.
- the blade pumping section L 1 comprises alternating rotor blades 130 and stator blades 132
- the groove pumping section L 2 comprises the spiral groove section 134 and the groove pumping section spacer 251 .
- the pump casing 114 is used to press down the stator blades 132 , the stator blade spacers 138 and the groove pumping section spacer 251 .
- the lower inner casing 250 and the spiral groove section spacer 251 are separately provided. That is, the stacked assembly comprising the stator blades 132 and the stator blade spacers 138 , and the spiral groove section spacer 251 are fixedly held by a lower inner casing 250 and an upper inner casing 253 , which are mutually fitted to construct an inner casing 252 .
- An impact absorbing member 286 is provided between the inner surfaces of the lower inner casing 250 and the upper inner casing 253 , and the outer surfaces of the stator blade spacers 138 and the spiral groove section spacer 251 .
- the impact absorbing member 286 is made of a material such as relatively soft metal, high polymer, or composite material thereof.
- the lower inner casing 250 comprises an outer cylindrical portion 250 A and an inner cylindrical portion 250 B connected by a connecting portion 250 C having a communicating hole 250 D.
- a friction reducing structure (mechanical bearing) 285 is provided between the inner surface of the inner cylindrical portion 250 B and the outer surface 247 a of the stator cylinder section 247 of the stator S.
- the impact absorbing member 286 is provided between the lower inner casing 250 and the upper inner casing 253 , and the stator blade spacers 138 and the spiral groove section spacer 251 , the amount of impact force transmitted to the inner casing 252 is reduced, which has been transmitted from the rotor R to the stator blade spacers 138 etc.
- the protection function of the inner casing 252 is improved, and hence the clearance T between the upper inner casing 253 or the lower inner casing 250 and the pump casing 114 can be smaller to enable the overall pump to be compact.
- another impact absorbing structure 254 is provided at the upstream of the blade pumping section L 1 , i.e., at an intake port 114 b of the turbo-molecular pump shown in FIG. 17.
- an extended portion 110 a is provided at the top of the main shaft 110
- an annular suppressing portion 254 a is formed at the top of the upper inner casing 253 .
- Stay members 254 b are provided to inwardly protrude from the annular suppressing portion 254 a and are connected to a ring-shaped upper inner cylindrical portion 254 c.
- the ring-shaped upper cylindrical portion 254 c surrounds the extended portion 110 a with a small gap t.
- the separate impact absorbing structure 254 is provided at the upstream of the blade pumping section L 1 , i.e., at the intake port 114 b of the turbo-molecular pump.
- the impact absorbing structure 254 serves as a scattering prevention member for preventing fragments of the rotor from being scattered through the intake port 114 b.
- FIGS. 19 and 20 show a turbo-molecular pump according to a twelfth embodiment of the present invention.
- the impact absorbing structure 254 at the entrance is mounted on a shaft body fixed to the stator S by way of friction reducing structure. That is, the upper end of the main shaft 110 is shorter, and a bearing supporting member 290 is provided to protrude inwardly from the top inner surface of the pump casing 114 .
- the bearing supporting member 290 comprises an annular section 290 a fixed to the pump casing 114 , stay members 290 b extending radially inwardly from the annular section 290 a, a disc 290 c connected to the stay members 290 b at the central region, and a cylindrical shaft 290 d extending downward from the disc 290 c.
- rectangular plate-like stay members 254 b are provided to radially inwardly extend from the annular suppressing portion 254 a of the upper inner casing 253 , and an upper inner cylindrical portion 254 c is formed at the central region of the stay members 254 b above the main shaft 110 .
- a mechanical bearing (friction reducing mechanism) 292 is provided between the outer surface of the shaft 290 d and the upper inner cylindrical portion 254 c.
- the impact absorbing structure 254 serves as a scattering prevention member for preventing fragments of the rotor from being scattered through the intake port 114 b.
- the bearing supporting member 290 also serves as a scattering prevention member for preventing fragments of the rotor from being scattered through the intake port 114 b.
- the scattering prevention member is effective to prevent those fragments from damaging the chamber in a processing apparatus connected to the intake port or devices and products being processed in the chamber.
- the various embodiments of the present invention are applied to the wide-range turbo-molecular pump which has the turbine blade pumping section L 1 and the thread groove pumping section L 2 .
- the principles of the present invention are also applicable to a turbo-molecular pump having either the turbine blade pumping section L 1 or the thread groove pumping section L 2 .
- the various embodiments of the present invention may be used in any one of possible combinations.
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Abstract
A turbo-molecular pump includes a casing having an intake port, a stator fixedly mounted in the casing, and a rotor supported in the casing for rotation relatively to the stator. The stator and the rotor make up a turbine blade pumping section and a groove pumping section for evacuating gas. A scattering prevention member is provided for preventing fragments of the rotor from being scattered through the intake port.
Description
- This is a continuation-in-part of application Ser. No. 09/473,137, filed Dec. 28, 1999.
- 1. Field of the Invention
- The present invention relates to a turbo-molecular pump for evacuating gas with a rotor that rotates at a high speed.
- 2. Description of the Related Art
- FIG. 21 of the accompanying drawings shows a conventional turbo-molecular pump. As shown in FIG. 21, the conventional turbo-molecular pump comprises a rotor R and a stator S which are housed in a
pump casing 14. The rotor R and the stator S jointly make up a turbine blade pumping section L1 and a thread groove pumping section L2. The stator S comprises abase 15, a stationarycylindrical sleeve 16 vertically mounted centrally on thebase 15, and stationary components of the turbine blade pumping section L1 and the thread groove pumping section L2. The rotor R mainly comprises amain shaft 10 inserted coaxially in the stationarycylindrical sleeve 16, and a rotarycylindrical sleeve 12 mounted on themain shaft 10 and disposed around the stationarycylindrical sleeve 16. - Between the
main shaft 10 and the stationarycylindrical sleeve 16, there are provided adrive motor 18, an upper radialmagnetic pole 20 disposed above thedrive motor 18, and a lower radialmagnetic pole 22 disposed below thedrive motor 18. Anaxial bearing 24 is disposed at a lower portion of themain shaft 10, and comprises atarget disk 24 a mounted on the lower end of themain shaft 10, and upper andlower electromagnets 24 b provided on the stator side. By this magnetic bearing system, the rotor R can be rotated at a high speed under 5-axis active control. - The rotary
cylindrical sleeve 12 hasrotor blades 30 integrally disposed on an upper outer circumferential portion thereof. In thepump casing 14, there are providedstator blades 32 disposed axially alternately with therotor blades 30. Therotor blades 30 and thestator blades 32 jointly make up the turbine blade pumping section L1 for evacuating gas by way of an interaction between therotor blades 30 and thestator blades 32. - The thread groove pumping section L2, which is disposed downwardly of the turbine blade pumping section L1, includes a
thread groove section 34 of the rotarycylindrical sleeve 12 which hasthread grooves 34 a defined in an outer circumferential surface thereof and surrounds the stationarycylindrical sleeve 16. The stator S has aspacer 36 disposed around thethread groove section 34. The thread groove pumping section L2 evacuates gas by way of a dragging action of thethread grooves 34 a in thethread groove section 34 which rotates at a high speed in unison with the rotor R. Thestator blades 32 have outer edges clamped by eitherstator blade spacers 38 or thestator blade spacer 38 and thespacer 36. - With the thread groove pumping section L2 disposed downstream of the turbine blade pumping section L1, the turbo-molecular pump is of the wide range type capable of handing a wide range of rates of gas flows. In the conventional turbo-molecular pump shown in FIG. 21, the
thread grooves 34 a of the thread groove pumping section L2 are defined in the rotor R. However, the thread grooves of the thread groove pumping section L2 may be defined in the stator S. - In such a turbo-molecular pump, if the rotor R is broken due to corrosion or the like, then fragments of the rotor R may enter an
intake port 14 a of thepump casing 14. When fragments of the rotarycylindrical sleeve 12 or therotor blades 30 which have large kinetic energy are introduced into the chamber of a processing apparatus that is connected to theintake port 14 a of thepump casing 14 through aflange 14 b, the processing apparatus may be broken or products that are being processed by the processing apparatus may be damaged, and the overall evacuating system may be destroyed, tending to cause a harmful processing gas to leak into the surrounding environment. - It is therefore an object of the present invention to provide a highly safe turbo-molecular pump which can prevent rotor fragments from damaging the chamber in a processing apparatus and products being processed by the processing apparatus even when a rotor of the turbo-molecular pump is broken, and which can be replaced in its entirety in case of destruction for quickly making the processing apparatus reusable.
- According to the present invention, there is provided a turbo-molecular pump comprising a casing having an intake port, a stator fixedly mounted in the casing, a rotor supported in the casing for rotation relatively to the stator, the stator and the rotor serving as at least one of a turbine blade pumping section and a thread groove pumping section for evacuating gas, and a scattering prevention member for preventing fragments of the rotor from being scattered through the intake port.
- If the rotor is broken, then fragments of the rotor, e.g., a rotary cylindrical sleeve and rotor blades, or fragments of the stator, e.g., stator blades, are blocked by the scattering prevention member, or lose the kinetic energy toward the intake port. Therefore, the scattering prevention member is effective to prevent those fragments from damaging the chamber in a processing apparatus connected to the intake port or devices and products being processed in the chamber. The scattering prevention member may be mounted on a stationary member such as the casing, or the rotor.
- The rotor comprises rotor blades and the stator comprises stator blades, and the scattering prevention member comprises at least part of the rotor blade or the stator blade. Therefore, at least part of the rotor blade or the stator blade has a fragment shield function.
- The scattering prevention member includes at least one protrusion projecting radially inwardly from an inner surface of the intake port. If the rotor is broken, rotor fragments collide with the protrusion, and are prevented from being scattered through the intake port or kinetic energy of the rotor fragments is reduced.
- The scattering prevention member is made of a high-strength material and/or a high-energy absorbing material. The high-strength material may be stainless steel, titanium alloy, or the like which is stronger than aluminum. The high-energy absorbing material may be made of a relatively soft metal material such as lead, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks, e.g., shaped into a honeycomb structure or an assembly of spherical members.
- The scattering prevention member has a shock absorbing structure. The shock absorbing structure is effective to absorb the kinetic energy of rotor fragments which collide with the scattering prevention member for better protection of the chamber in the processing apparatus that is connected to the intake port.
- The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
- FIG. 1 is an axial cross-sectional view of a turbo-molecular pump according to a first embodiment of the present invention;
- FIG. 2 is a plan view of the turbo-molecular pump shown in FIG. 1;
- FIG. 3 is an axial cross-sectional view of a turbo-molecular pump according to a second embodiment of the present invention;
- FIG. 4 is an axial cross-sectional view of a turbo-molecular pump according to a third embodiment of the present invention;
- FIG. 5 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 4;
- FIG. 6 is an axial cross-sectional view of a turbo-molecular pump according to a fourth embodiment of the present invention;
- FIG. 7 is a plan view of the turbo-molecular pump shown in FIG. 6;
- FIG. 8 is an axial cross-sectional view of a turbo-molecular pump according to a fifth embodiment of the present invention;
- FIG. 9 is an axial cross-sectional view of a turbo-molecular pump according to a sixth embodiment of the present invention;
- FIG. 10 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 9;
- FIG. 11 is a plan view of metal pipes of a shock absorbing member used in the turbo-molecular pump shown in FIG. 9;
- FIG. 12 is an axial cross-sectional view of a turbo-molecular pump according to a seventh embodiment of the present invention;
- FIG. 13 is an axial cross-sectional view of a turbo-molecular pump according to an eighth embodiment of the present invention;
- FIG. 14 is an axial cross-sectional view of a turbo-molecular pump according to a ninth embodiment of the present invention;
- FIG. 15 is an enlarged fragmentary cross-sectional view of the turbo-molecular pump shown in FIG. 14;
- FIG. 16 is an axial cross-sectional view of a turbo-molecular pump according to a tenth embodiment of the present invention;
- FIG. 17 is an axial cross-sectional view of a turbo-molecular pump according to an eleventh embodiment of the present invention;
- FIG. 18 is a plan view of the turbo-molecular pump shown in FIG. 17;
- FIG. 19 is an axial cross-sectional view of a turbo-molecular pump according to a twelfth embodiment of the present invention;
- FIG. 20 is a plan view of the turbo-molecular pump shown in FIG. 19; and
- FIG. 21 is an axial cross-sectional view of a conventional turbo-molecular pump.
- Next, a turbo-molecular pump according to embodiments of the present invention will be described below. Like or corresponding parts are denoted by like or corresponding reference characters throughout views. Those parts of turbo-molecular pumps according to the present invention which are identical to those of the conventional turbo-molecular pump shown in FIG. 21 are denoted by identical reference characters, and will not be described in detail below.
- FIGS. 1 and 2 show a turbo-molecular pump according to a first embodiment of the present invention. As shown in FIGS. 1 and 2, the turbo-molecular pump according to the first embodiment has a
protective cover 50 serving as a scattering prevention member mounted on theflange 14 b around theintake port 14 a in thepump casing 14. Theprotective cover 50 comprises acircular shield 52 disposed centrally in theintake port 14 a in covering relationship to an area directly above the rotarycylindrical sleeve 12 of the rotor R, a ring-shapedrim 56 disposed concentrically with and radially outwardly of thecircular shield 52 and having an opening whose size is the same as the size of theintake port 14 a, and a plurality of (three in FIG. 2) support bars 54 extending radially outwardly from thecircular shield 52 to connect thecircular shield 52 and therim 56 to each other. In FIG. 1, theprotective cover 50 has astep 56 a on the lower surface of therim 56 which is fitted over theflange 14 b, so that theprotective cover 50 is fixed to thepump casing 14. However, theflange 14 b may have a step, and theprotective cover 50 may be fitted in the step and fastened to theflange 14 b by bolts. Alternatively, theprotective cover 50 may be fitted in the step in theflange 14 b and simply sandwiched between thepump casing 14 and the chamber in the processing apparatus to which the turbo-molecular pump is connected. - The axially
uppermost stator blade 32 a of all thestator blades 32 is made of a material stronger than aluminum, such as stainless steel, titanium alloy, or the like, and the remainingstator blades 32 are made of aluminum. Thus, thestator blade 32 a also serves as a scattering prevention member. - With the turbo-molecular pump having the above structure, if the rotor R is broken due to corrosion or the like while it is rotating, fragments of the rotary
cylindrical sleeve 12 or therotor blades 30 in the rotor R collide with theshield 52 of theprotective cover 50, thereby losing their kinetic energy toward theintake port 14 a. Therefore, the chamber or the like connected to theintake port 14 a of thepump casing 14 is prevented from being damaged, or the degree of damage of the chamber or the like is reduced. In the embodiment shown in FIG. 1, theshield 52 covers only the rotarycylindrical sleeve 12. However, theshield 52 may cover not only the rotarycylindrical sleeve 12, but also part of therotor blades 30. - Since the axially
uppermost stator blade 32 a of thestator blades 32 is made of a material stronger than aluminum, thestator blade 32 a is not broken or is broken to a lesser degree when it is hit by fragments of therotor blades 30 made of aluminum. Thestator blade 32 a thus effectively serves as a scattering prevention member for preventing fragments from being scattered through theintake port 14 a. - In the first embodiment, only the
uppermost stator blade 32 a of thestator blades 32 is made of a high-strength material. However, any otherarbitrary stator blades 32, e.g., first- and fourth-stage stator blades 32 may be made of a high-strength material. This holds true for other embodiments of the present invention. - In the first embodiment, the
protective cover 50 is provided as a scattering prevention member, and also theuppermost stator blade 32 a of thestator blades 32 is made of a material stronger than aluminum as a scattering prevention member. However, eitherprotective cover 50 may be provided or theuppermost stator blade 32 a may be made of a material stronger than aluminum. The turbo-molecular pump in other embodiments described later may have the same structure as the turbo-molecular pump in the first embodiment. - FIG. 3 shows a turbo-molecular pump according to a second embodiment of the present invention. According to the second embodiment, the
circular shield 52 of theprotective cover 50 according to the first embodiment is replaced with a substantiallycylindrical shield 58. The substantiallycylindrical shield 58 has a substantially lower half disposed in arecess 13 defined centrally in the rotarycylindrical sleeve 12. Other details of the turbo-molecular pump according to the second embodiment are identical to those of the turbo-molecular pump according to the first embodiment. - With the turbo-molecular pump according to the second embodiment, the gap between the
shield 58 and the rotor R is reduced to lower the possibility of fragments to be scattered around for better protection of the chamber to which the turbo-molecular pump is connected. Theshield 58 also performs an attitude maintaining function to keep the rotor R in its proper attitude when the rotor R suffers abnormal rotation. Any unwanted contact between the rotor R and the stator W can therefore be minimized to reduce the possibility of fragment production. - FIGS. 4 and 5 shows a turbo-molecular pump according to a third embodiment of the present invention. According to the third embodiment, the turbo-molecular pump includes a scattering prevention member having a shock absorbing structure. Specifically, the
protective cover 50 as a scattering prevention member has a substantiallycircular shield 70 disposed centrally therein and having ashank 70 a projecting downwardly, and ashock absorbing member 74 comprisingmetal pipes 72 wound in two coil-like layers around theshank 70 a. Theshock absorbing member 74 is surrounded by a cup-shapedcover 76 which is open upwardly. Theshield 70 has a peripheral edge fastened to a flange of thecover 76 bybolts 78. Thecover 76 is disposed so as to enter therecess 13 defined centrally in the rotarycylindrical sleeve 12. - With the turbo-molecular pump of this embodiment, if the rotor R is broken, then fragments of the
rotor blades 30 or the rotarycylindrical sleeve 12 collide with theshield 70 and thecover 76. At this time, theshock absorbing member 74 can easily be deformed or broken in both axial and radial directions to absorb applied shocks. Therefore, the kinetic energy of the fragments is absorbed to protect the chamber to which the turbo-molecular pump is connected. - The
shock absorbing member 74 may alternatively be made of a relatively soft metal material such as lead, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks, e.g., shaped into a honeycomb structure or an assembly of spherical members. In view of applications of the turbo-molecular pump for evacuating corrosive gases, theshock absorbing member 74 should preferably be made of a corrosion-resistant material or be treated to provide a corrosion-resistant surface such as a nickel coating. - FIG. 6 and7 show a turbo-molecular pump according to a fourth embodiment of the present invention. The turbo-molecular pump according to the fourth embodiment differs from the turbo-molecular pump according to the first embodiment in the following: A plurality of (three in FIG. 7)
protrusions 60, which make up a scattering prevention member together with theprotective cover 50, are disposed at predetermined intervals on an inner surface of theintake port 14 a and project radially inwardly in covering relationship to the outer circumferential edges of therotor blades 30 of the rotor R. While theprotrusions 60 are shown as being disposed on the inner surface of theintake port 14 a, theprotrusions 60 may alternatively be disposed on therim 56 of theprotective cover 50. - With the turbo-molecular pump according to the fourth embodiment, if the rotor R is broken, then fragments of the
rotor blades 30 and the rotarycylindrical sleeve 12 collide with not only theshield 52 but also theprotrusions 60, thus reducing the kinetic energy of the fragments introduced into theintake port 14 a. - FIG. 8 shows a turbo-molecular pump according to a fifth embodiment of the present invention. The turbo-molecular pump according to the fifth embodiment has a
scattering prevention member 62 mounted on the upper end of themain shaft 10 of the rotor R in covering relationship to the upper surface of the rotarycylindrical sleeve 12 that faces theintake port 14 a. Thescattering prevention member 62 is of a cup shape complementary to therecess 13 in the rotarycylindrical sleeve 12 and has aflange 62 a on its upper end which extends along the flat upper surface of the rotarycylindrical sleeve 12. Thescattering prevention member 62 has an internally threaded hole defined in a bottom thereof. Themain shaft 10 has a fixedportion 10 a at the upper end thereof and having an externally threaded surface. Thescattering prevention member 62 is fastened to themain shaft 10 by the fixedportion 10 a that is threaded into the internally threaded hole in thescattering prevention member 62. Thescattering prevention member 62 may alternatively be fastened to themain shaft 10 or the rotarycylindrical sleeve 12 by other fasteners such as bolts. - With the turbo-molecular pump according to the fifth embodiment, since the
scattering prevention member 62 is mounted on the rotor R, it is not necessary to provide an obstacle which would otherwise extend across theintake port 14 a for installing thescattering prevention member 62. Therefore, the velocity of the gas that is evacuated by the turbo-molecular pump is not lowered. Furthermore, because thescattering prevention member 62 is disposed in covering relationship to therecess 13 where fragments of the rotor R tend to be scattered, thescattering prevention member 62 is effective to efficiently prevent fragments of the rotor R from being scattered. While thescattering prevention member 62 is disposed in covering relationship to the rotarycylindrical sleeve 12 in the illustrated embodiment, thescattering prevention member 62 may be disposed so as to cover part of therotor blades 30. - FIGS. 9 through 11 show a turbo-molecular pump according to a sixth embodiment of the present invention. The turbo-molecular pump according to the sixth embodiment differs from the turbo-molecular pump according to the fifth embodiment in that a shock absorbing structure is added to the
scattering prevention member 62 according to the fifth embodiment. Other details of the turbo-molecular pump according to the sixth embodiment are identical to those of the turbo-molecular pump according to the fifth embodiment. - In the sixth embodiment, the upwardly open
scattering prevention member 62 houses therein ashock absorbing member 82 comprising a pair of vertical stacks of semiannular metal pipes 80 (see FIG. 11) in radially confronting relationship to each other. Themain shaft 10 has a vertical extension having an externally threaded upper end. Anut 84 as a shock absorbing member holder is threaded over the externally threaded upper end of the extension of themain shaft 10, thus holding theshock absorbing member 82 against removal. Thenut 84 is fastened to cause theshock absorbing member 82 to press the lower surface of theflange 62 a thereof against the rotarycylindrical sleeve 12 for thereby securing thescattering prevention member 62. - If the rotor R is broken, then fragments of the
rotor blades 30 or the rotarycylindrical sleeve 12 collide with thescattering prevention member 62. At this time, theshock absorbing member 82 can easily be deformed or broken in both axial and radial directions to absorb applied shocks. Therefore, the kinetic energy of the fragments is absorbed to protect the chamber or the like to which the turbo-molecular pump is connected. - The
semiannular metal pipes 80 are used to make up theshock absorbing member 82 for the reason of better productivity. Alternatively, fully circular metal pipes, annular metal pipes with open gaps, or coil-shaped metal pipes may also be employed. Theshock absorbing member 82 may alternatively be made of a relatively soft metal material, a polymer material, or a composite material thereof, and shaped so as to be effective to absorb shocks. - FIG. 12 shows a turbo-molecular pump according to a seventh embodiment of the present invention. The turbo-molecular pump according to the seventh embodiment differs from the turbo-molecular pump according to the fifth embodiment in that the cup-shaped
scattering prevention member 62 is replaced with a disk-shapedscattering prevention member 64 that is housed in therecess 13 in the rotarycylindrical sleeve 12. Other details of the turbo-molecular pump according to the seventh embodiment are identical to those of the turbo-molecular pump according to the fifth embodiment. Usually, the rotarycylindrical sleeve 12 has anupper portion 12 a integral with ahub 12 b thereof. Therefore, only by simply holding thehub 12 b with the disk-shapedscattering prevention member 64, rotor fragments is effectively prevented from being scattered. The turbo-molecular pump according to the seventh embodiment is less costly than the turbo-molecular pump according to the fifth embodiment. - FIG. 13 shows a turbo-molecular pump according to an eighth embodiment of the present invention. The turbo-molecular pump according to the eighth embodiment differs from the turbo-molecular pump according to the fifth embodiment in that the cup-shaped
scattering prevention member 62 is fastened to the rotarycylindrical sleeve 12 bybolts 66 and also differs therefrom in the following: A plurality of (three in the illustrated embodiment)protrusions 60, which make up a scattering prevention member together with thescattering prevention member 62, are disposed at predetermined intervals on an inner surface of theintake port 14 a and project radially inwardly in covering relationship to the outer circumferential edges of therotor blades 30 of the rotor R. - With the turbo-molecular pump according to the eighth embodiment, if the rotor R is broken, then fragments of the
rotor blades 30 or the rotarycylindrical sleeve 12 collide with not only thescattering prevention member 62 but also theprotrusions 60, thus reducing the kinetic energy of the fragments introduced into theintake port 14 a. In all the embodiments, the scattering prevention member including the protrusions should preferably be made of a high-strength material such as stainless steel, titanium alloy, or the like. - FIGS. 14 and 15 show a turbo-molecular pump according to a ninth embodiment of the present invention. The turbo-molecular pump according to the ninth embodiment differs from the turbo-molecular pump according to the eighth embodiment in that a shock absorbing structure is added to the
scattering prevention member 62 fastened to the rotarycylindrical sleeve 12 according to the eighth embodiment. Other details of the turbo-molecular pump according to the ninth embodiment are identical to those of the turbo-molecular pump according to the eighth embodiment. - In the ninth embodiment, a
support 90 having ashank 90 a is vertically mounted in therecess 13 in the rotarycylindrical sleeve 12 and fastened to the bottom of therecess 13 bybolts 92. Thescattering prevention member 62 houses therein ashock absorbing member 96 comprising a pair of vertical stacks of semiannular metal pipes 80 (see FIG. 11) in radially confronting relationship to each other and a plurality of O-rings 94 of fluororubber interposed between thepipes 80 and thescattering prevention member 62. Theshank 90 a has a vertical extension having an externally threaded upper end. Anut 98 as a shock absorbing member holder is threaded over the externally threaded upper end of the extension of theshank 90 a, thus holding theshock absorbing member 96 against removal. Thescattering prevention member 62 is limited against its axial movement by thepipes 80 and limited against its radial movement by the O-rings 94. The shock absorbing structure is capable of absorbing shocks due to collision with rotor fragments or stator fragments in both the axial and radial directions. - As shown in FIG. 15, an
annular ledge 12 c is disposed on the upper surface of the rotarycylindrical sleeve 12 around therecess 13, and anannular ridge 62 c is disposed on the lower surface of a peripheral edge of theflange 62 a of thescattering prevention member 62. Theannular ridge 62 c define arecess 62 b in the lower surface of theflange 62 a. When theannular ledge 12 c is fitted in therecess 62 b in the lower surface of theflange 62 a, thescattering prevention member 62 is coaxially aligned with the rotarycylindrical sleeve 12 and held against radial movement. - With the turbo-molecular pump according to the ninth embodiment, if the rotor R is broken, fragments of the
rotor blades 30 or the rotarycylindrical sleeve 12 collide with thescattering prevention member 62. At this time, theshock absorbing member 96 is deformed or broken to absorb the kinetic energy of the fragments. Since fragments also collide with theprotrusions 60, the kinetic energy of the fragments introduced into theintake port 14 a can further be reduced. - FIG. 16 shows a turbo-molecular pump according to a tenth embodiment of the present invention. According to the tenth embodiment, the axially
uppermost rotor blade 30 a of allrotor blades 30 is separate from theother rotor blades 30 and is made of a material stronger than aluminum, such as stainless steel, titanium alloy, or the like, and the remainingrotor blades 30 are made of aluminum. Theuppermost rotor blade 30 a is directly fastened to themain shaft 10 bybolts 100, and serves as a scattering prevention member. - Since the
uppermost rotor blade 30 a is made of a material stronger than aluminum, therotor blade 30 a is not broken or is broken to a lesser degree when it is hit by fragments of the remainingrotor blades 30 made of aluminum. Therotor blade 30 a thus effectively serves as a scattering prevention member for preventing fragments from being scattered through theintake port 14 a. - FIGS. 17 and 18 show a turbo-molecular pump according to an eleventh embodiment of the present invention.
- The turbo-molecular pump comprises a
cylindrical pump casing 114 housing a blade pumping section L1 and a groove pumping section L2 which are constituted by a rotor (rotation member) R and a stator (stationary member) S. The bottom portion of thepump casing 114 is covered by abase section 115 which is provided with anexhaust port 115 a. The top portion of thepump casing 114 is provided with aflange section 114 a for coupling the turbo-molecular pump to an apparatus or a piping to be evacuated. The stator S comprises astator cylinder section 247 provided on the center of thebase section 115, and stationary sections of the blade pumping section L1 and the groove pumping section L2. - The rotor R comprises a rotor cylinder section112 attached to a
main shaft 110 which is inserted into thestator cylinder section 247. Between themain shaft 110 and thestator cylinder section 247, there are provided adrive motor 118, an upperradial bearing 120 and a lowerradial bearing 122 disposed on the upper and lower sides ofdrive motor 118, respectively. At the lower part of themain shaft 110, there is provided anaxial bearing 124 having atarget disk 124 a at the bottom end of themain shaft 110 and an upper and lower electromagnets; 124 b on the stator side. In this configuration, the rotor R can be rotated at a high speed under a five coordinate active control system. - Rotor blades (rotor vanes)130 are provided integrally with the upper external surface of the rotor cylinder section 112, and on the inside of the
pump casing 114, stator blades (stator vanes) 132 are provided in such a way to alternately interweave with therotor blades 130. These blade members constitute the blade pumping section L1 which carries out gas evacuation by cooperative action of the high-speed therotor blades 130 and thestationary stator blades 132. Below the blade pumping section L1, the groove pumping section L2 is provided. The groove pumping section L2 comprises aspiral groove section 134 havingspiral grooves 134 a on the outer surface of the lower portion of the rotor cylinder section 112, and the stator S comprises a spiralgroove section spacer 251 surrounding thespiral groove section 134. Gas evacuation action of the groove pumping section L2 is caused by the dragging effect of thespiral grooves 134 a of thespiral groove section 134. - By providing the groove pumping section L2 downstream of the blade pumping section L1, a wide-range of the turbo-molecular pump can be constructed so as to enable evacuation over a wide range of gas flow rates using one pumping unit. In this example, the spiral grooves of the groove pumping section L2 are provided on the rotor side of the pump structure, but the spiral grooves may be formed on the stator side of the pump structure.
- The blade pumping section L1 comprises alternating
rotor blades 130 andstator blades 132, and the groove pumping section L2 comprises thespiral groove section 134 and the groovepumping section spacer 251. Thepump casing 114 is used to press down thestator blades 132, thestator blade spacers 138 and the groovepumping section spacer 251. - In this embodiment, the lower
inner casing 250 and the spiralgroove section spacer 251 are separately provided. That is, the stacked assembly comprising thestator blades 132 and thestator blade spacers 138, and the spiralgroove section spacer 251 are fixedly held by a lowerinner casing 250 and an upperinner casing 253, which are mutually fitted to construct aninner casing 252. - An
impact absorbing member 286 is provided between the inner surfaces of the lowerinner casing 250 and the upperinner casing 253, and the outer surfaces of thestator blade spacers 138 and the spiralgroove section spacer 251. Theimpact absorbing member 286 is made of a material such as relatively soft metal, high polymer, or composite material thereof. - The lower
inner casing 250 comprises an outercylindrical portion 250A and an innercylindrical portion 250B connected by a connectingportion 250C having a communicatinghole 250D. A friction reducing structure (mechanical bearing) 285 is provided between the inner surface of the innercylindrical portion 250B and theouter surface 247 a of thestator cylinder section 247 of the stator S. - In this embodiment, since a clearance T is formed between the
inner casing 252 and thepump casing 114, even when a part of theinner casing 252 is broken or deformed, the impact is not directly transmitted to thepump casing 114 to thus prevent breakage of thepump casing 114 or its connection with other facilities or devices. - In this embodiment, since the
impact absorbing member 286 is provided between the lowerinner casing 250 and the upperinner casing 253, and thestator blade spacers 138 and the spiralgroove section spacer 251, the amount of impact force transmitted to theinner casing 252 is reduced, which has been transmitted from the rotor R to thestator blade spacers 138 etc. Thus, the protection function of theinner casing 252 is improved, and hence the clearance T between the upperinner casing 253 or the lowerinner casing 250 and thepump casing 114 can be smaller to enable the overall pump to be compact. - As shown in FIGS. 17 and 18, in this embodiment, another
impact absorbing structure 254 is provided at the upstream of the blade pumping section L1, i.e., at anintake port 114 b of the turbo-molecular pump shown in FIG. 17. Specifically, anextended portion 110 a is provided at the top of themain shaft 110, and an annular suppressingportion 254 a is formed at the top of the upperinner casing 253. Staymembers 254 b are provided to inwardly protrude from the annular suppressingportion 254 a and are connected to a ring-shaped upper innercylindrical portion 254 c. The ring-shaped uppercylindrical portion 254 c surrounds theextended portion 110 a with a small gap t. - With the turbo-molecular pump according to the eleventh embodiment, the separate
impact absorbing structure 254 is provided at the upstream of the blade pumping section L1, i.e., at theintake port 114 b of the turbo-molecular pump. Theimpact absorbing structure 254 serves as a scattering prevention member for preventing fragments of the rotor from being scattered through theintake port 114 b. - FIGS. 19 and 20 show a turbo-molecular pump according to a twelfth embodiment of the present invention. In this embodiment, the
impact absorbing structure 254 at the entrance is mounted on a shaft body fixed to the stator S by way of friction reducing structure. That is, the upper end of themain shaft 110 is shorter, and abearing supporting member 290 is provided to protrude inwardly from the top inner surface of thepump casing 114. - The
bearing supporting member 290 comprises anannular section 290 a fixed to thepump casing 114, staymembers 290 b extending radially inwardly from theannular section 290 a, adisc 290 c connected to thestay members 290 b at the central region, and acylindrical shaft 290 d extending downward from thedisc 290 c. On the other hand, rectangular plate-like stay members 254 b are provided to radially inwardly extend from the annular suppressingportion 254 a of the upperinner casing 253, and an upper innercylindrical portion 254 c is formed at the central region of thestay members 254 b above themain shaft 110. A mechanical bearing (friction reducing mechanism) 292 is provided between the outer surface of theshaft 290 d and the upper innercylindrical portion 254 c. - The
impact absorbing structure 254 serves as a scattering prevention member for preventing fragments of the rotor from being scattered through theintake port 114 b. Thebearing supporting member 290 also serves as a scattering prevention member for preventing fragments of the rotor from being scattered through theintake port 114 b. - As described above, according to the eleventh and twelfth embodiments shown in FIGS. 17 through 20, if the rotor is broken, then fragments of the rotor, e.g., a rotary cylindrical sleeve and rotor blades, or fragments of the stator, e.g., stator blades, are blocked by the scattering prevention member, or lose the kinetic energy toward the intake port. Therefore, the scattering prevention member is effective to prevent those fragments from damaging the chamber in a processing apparatus connected to the intake port or devices and products being processed in the chamber.
- As described above, the various embodiments of the present invention are applied to the wide-range turbo-molecular pump which has the turbine blade pumping section L1 and the thread groove pumping section L2. However, the principles of the present invention are also applicable to a turbo-molecular pump having either the turbine blade pumping section L1 or the thread groove pumping section L2. Furthermore, the various embodiments of the present invention may be used in any one of possible combinations.
- With the present invention, as described above, while the rotor is rotated, fragments of the rotary cylindrical sleeve or the rotor blades produced when the rotor is broken collide with the scattering prevention member and are prevented from being scattered through the intake port, or lose their kinetic energy. Thus, those fragments are prevented from causing damage to the chamber connected to the intake port or devices and products being processed in the chamber. Therefore, even if the rotor is broken, the turbo-molecular pump effectively prevents accidents which would otherwise lead to damage to the chamber or destruction of the evacuating system. Consequently, the turbo-molecular pump according to the present invention is highly safe while it is in operation.
- Although certain preferred embodiments of the pre-sent invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.
Claims (6)
1. A turbo-molecular pump comprising:
a casing having an intake port;
a stator fixedly mounted in said casing;
a rotor supported in said casing for rotation relatively to said stator, said stator and said rotor serving as at least one of a turbine blade pumping section and a groove pumping section for evacuating gas; and
a scattering prevention members for preventing fragments of at least one of said rotor and said stator from being scattered through said intake port.
2. A turbo-molecular pump according to claim 1 , wherein said rotor comprises rotor blades and said stator comprises stator blades, and said scattering prevention member comprises at least part of said rotor blade or said stator blade
3. A turbo-molecular pump according to claim 1 , wherein said scattering prevention member includes at least one protrusion projecting radially inwardly from an inner surface of said intake port.
4. A turbo-molecular pump according to claim 1 , wherein said scattering prevention member is made of a high-strength material.
5. A turbo-molecular pump according to claim 1 , wherein said scattering prevention member is made of a high-energy absorbing material.
6. A turbo-molecular pump according to claim 1 , wherein said scattering prevention member has a shock absorbing structure.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US10/244,740 US20030017047A1 (en) | 1998-06-25 | 2002-09-17 | Turbo-molecular pump |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
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US09/104,171 US6332752B2 (en) | 1997-06-27 | 1998-06-25 | Turbo-molecular pump |
JP11-166637 | 1999-06-14 | ||
JP16663799 | 1999-06-14 | ||
US09/473,137 US6926493B1 (en) | 1997-06-27 | 1999-12-28 | Turbo-molecular pump |
US09/592,411 US6589009B1 (en) | 1997-06-27 | 2000-06-13 | Turbo-molecular pump |
US10/244,740 US20030017047A1 (en) | 1998-06-25 | 2002-09-17 | Turbo-molecular pump |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/592,411 Division US6589009B1 (en) | 1997-06-27 | 2000-06-13 | Turbo-molecular pump |
Publications (1)
Publication Number | Publication Date |
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US20030017047A1 true US20030017047A1 (en) | 2003-01-23 |
Family
ID=27474077
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US10/244,740 Abandoned US20030017047A1 (en) | 1998-06-25 | 2002-09-17 | Turbo-molecular pump |
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US (1) | US20030017047A1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050048768A1 (en) * | 2003-08-26 | 2005-03-03 | Hiroaki Inoue | Apparatus and method for forming interconnects |
US20060273090A1 (en) * | 2005-06-03 | 2006-12-07 | Toyoda Gosei Co., Ltd. | Lid device |
US20110014073A1 (en) * | 2008-03-31 | 2011-01-20 | Shimadzu Corporation | Turbo-molecular pump |
US20110293401A1 (en) * | 2009-02-24 | 2011-12-01 | Tokyo Electron Limited | Turbomolecular pump, and particle trap for turbomolecular pump |
US20130230384A1 (en) * | 2010-11-24 | 2013-09-05 | Edwards Japan Limited | Splinter shield for vacuum pump, and vacuum pump with the splinter shield |
US8961104B2 (en) | 2009-11-02 | 2015-02-24 | Shimadzu Corporation | Vacuum pump |
US20160084993A1 (en) * | 2013-06-12 | 2016-03-24 | Lg Chem, Ltd. | Method for preparing polarizing plate including operation of adjusting polarizer color by uv irradiation |
US20210355966A1 (en) * | 2018-10-31 | 2021-11-18 | Edwards Japan Limited | Vacuum pump, protective net, and contact part |
US20230313804A1 (en) * | 2019-10-09 | 2023-10-05 | Edwards Limited | Vacuum pump comprising an axial magnetic bearing and a radial gas foil bearing |
-
2002
- 2002-09-17 US US10/244,740 patent/US20030017047A1/en not_active Abandoned
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050048768A1 (en) * | 2003-08-26 | 2005-03-03 | Hiroaki Inoue | Apparatus and method for forming interconnects |
US20060273090A1 (en) * | 2005-06-03 | 2006-12-07 | Toyoda Gosei Co., Ltd. | Lid device |
US20110014073A1 (en) * | 2008-03-31 | 2011-01-20 | Shimadzu Corporation | Turbo-molecular pump |
US8591204B2 (en) | 2008-03-31 | 2013-11-26 | Shimadzu Corporation | Turbo-molecular pump |
US20110293401A1 (en) * | 2009-02-24 | 2011-12-01 | Tokyo Electron Limited | Turbomolecular pump, and particle trap for turbomolecular pump |
US8894355B2 (en) * | 2009-02-24 | 2014-11-25 | Shimadzu Corporation | Turbomolecular pump, and particle trap for turbomolecular pump |
US8961104B2 (en) | 2009-11-02 | 2015-02-24 | Shimadzu Corporation | Vacuum pump |
US20130230384A1 (en) * | 2010-11-24 | 2013-09-05 | Edwards Japan Limited | Splinter shield for vacuum pump, and vacuum pump with the splinter shield |
US9816530B2 (en) * | 2010-11-24 | 2017-11-14 | Edwards Japan Limited | Splinter shield for vacuum pump, and vacuum pump with the splinter shield |
US20160084993A1 (en) * | 2013-06-12 | 2016-03-24 | Lg Chem, Ltd. | Method for preparing polarizing plate including operation of adjusting polarizer color by uv irradiation |
US20210355966A1 (en) * | 2018-10-31 | 2021-11-18 | Edwards Japan Limited | Vacuum pump, protective net, and contact part |
US20230313804A1 (en) * | 2019-10-09 | 2023-10-05 | Edwards Limited | Vacuum pump comprising an axial magnetic bearing and a radial gas foil bearing |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: EXPRESSLY ABANDONED -- DURING EXAMINATION |