US20130259712A1 - Vacuum evacuation apparatus - Google Patents

Vacuum evacuation apparatus Download PDF

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Publication number
US20130259712A1
US20130259712A1 US13/849,719 US201313849719A US2013259712A1 US 20130259712 A1 US20130259712 A1 US 20130259712A1 US 201313849719 A US201313849719 A US 201313849719A US 2013259712 A1 US2013259712 A1 US 2013259712A1
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United States
Prior art keywords
vacuum pump
vacuum
pump
evacuation
evacuation apparatus
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
Application number
US13/849,719
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English (en)
Inventor
Hiroyuki Kawasaki
Hiroshi Sobukawa
Atsushi Oyama
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Ebara Corp
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Ebara Corp
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Assigned to EBARA CORPORATION reassignment EBARA CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAWASAKI, HIROYUKI, OYAMA, ATSUSHI, SOBUKAWA, HIROSHI
Publication of US20130259712A1 publication Critical patent/US20130259712A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B25/00—Multi-stage pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
    • 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
    • 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
    • F04D19/046—Combinations of two or more different types of pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D25/00—Pumping installations or systems
    • F04D25/16—Combinations of two or more pumps ; Producing two or more separate gas flows

Definitions

  • the present invention relates to a vacuum evacuation apparatus which is capable of compressing a gas from an ultrahigh vacuum to an atmospheric pressure, and more particularly to a vacuum evacuation apparatus which can be mounted in a posture that can freely be selected.
  • turbomolecular pump serves to evacuate the chamber to an ultrahigh vacuum range
  • dry vacuum pump serves to evacuate the chamber in a range from an atmospheric pressure to a medium vacuum.
  • the turbomolecular pump and the dry vacuum pump are driven by respective power supplies and individually controlled in operation.
  • the turbomolecular pump and the dry vacuum pump are thus used as vacuum pumps in different vacuum ranges.
  • a turbomolecular pump it is necessary to initially use a dry vacuum pump to evacuate the chamber to a rough vacuum range, i.e., a medium vacuum range, in which the turbomolecular pump can be used to further evacuate the chamber. Therefore, it is essential to install the dry vacuum pump as a roughing vacuum pump in order to use the turbomolecular pump.
  • turbomolecular pump As one advanced concept of the turbomolecular pump, an atmospheric pressure-evacuation-type turbomolecular pump which can evacuate the chamber from an atmospheric pressure range has been proposed.
  • turbomolecular pump has not yet been fully developed into a practically feasible product on account of various problems about requirements for mechanical strength of a rotor that needs to rotate at ultrahigh speeds, radiation of the heat of a compressed gas produced at the time of evacuation from an atmospheric pressure range to an ultrahigh vacuum range, the structure of a motor that needs large torques and ultrahigh-speed rotation, and a driving power supply source.
  • a positive displacement vacuum pump such as an oil rotary pump, a roots dry pump, or a screw dry pump which is capable of creating a vacuum in the range from several Torr to 10 ⁇ 2 Torr, and a kinetic vacuum pump (turbomolecular pump) or an entrapment vacuum pump (cryopump), disposed upstream of the positive displacement vacuum pump, for creating an ultrahigh vacuum
  • a kinetic vacuum pump turbomolecular pump
  • entrapment vacuum pump cryopump
  • the positive displacement vacuum pump is mostly installed or placed on an installation surface such as a ground surface, and the kinetic vacuum pump or the entrapment vacuum pump is installed in the vicinity of a vacuum container (vacuum chamber) to be evaluated to an ultrahigh vacuum or is directly connected to the vacuum container (vacuum chamber).
  • the vacuum pump that is installed in the vicinity of the vacuum container or is directly connected to the vacuum container is referred to as a first vacuum pump, and the vacuum pump that is installed or placed on the installation surface such as a ground surface is referred to as a second vacuum pump.
  • the second vacuum pump is not installed in the vicinity of the vacuum container because of its vibrations or noise or because it uses oil, but is installed at a remote location, e.g., at a downstairs installation site.
  • the second vacuum pump is connected to the first vacuum pump by a long vacuum piping.
  • the second vacuum pump needs to have evacuation capacity in view of the conductance of the vacuum piping, i.e., to have larger capacity as required by the conductance of the vacuum piping.
  • Vacuum pumps having a single rotational shaft which can compress a gas from an ultrahigh vacuum to an atmospheric pressure are disclosed in the following documents:
  • the disclosed vacuum pump is a kinetic vacuum pump, which includes a helical screw pump section and a centrifugal pump section, for compressing a gas from an ultrahigh vacuum to an atmospheric pressure. Since turbine blades and centrifugal blades are mounted in series on one rotational shaft, the centrifugal blades which are located at an atmospheric pressure side have a poor evacuation efficiency in the atmospheric pressure range, and thus the vacuum pump requires large driving power.
  • the disclosed vacuum pump is a kinetic vacuum pump, which includes a centrifugal compression pump stage and a circumferential flow compression pump stage, for compressing a gas from an ultrahigh vacuum to an atmospheric pressure. Since centrifugal blades and vortex flow blades are mounted in series on one rotational shaft, the vortex flow blades which are located at an atmospheric pressure side have a poor evacuation efficiency in the atmospheric pressure range, and thus the vacuum pump requires large driving power.
  • a highly efficient evacuation system can be realized.
  • the displacement vacuum pump cannot be installed in the vicinity of a vacuum container (vacuum chamber) because of its vibrations, heat generated when a gas is compressed to an atmospheric pressure, and the like.
  • a single vacuum pump which is capable of compressing a gas from an ultrahigh vacuum to an atmospheric pressure has a problem of limitations of evacuation performance and a problem of increased driving power.
  • the present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a vacuum evacuation apparatus which is capable of compressing a gas from an ultrahigh vacuum to an atmospheric pressure, simplifying an evacuation system and reducing a driving power for higher efficiency, and can be installed in any desired directions in the vicinity of a vacuum container or directly on the vacuum container.
  • a vacuum evacuation apparatus for evacuating a container from an atmospheric pressure to a high vacuum or less, comprising: a first vacuum pump for evacuating the container to a high vacuum or less; and a second vacuum pump for evacuating the container from an atmospheric pressure to a medium or low vacuum; wherein the first vacuum pump and the second vacuum pump are integrally connected to each other into an integral unit.
  • the high vacuum means a pressure range from 0.1 to 10 ⁇ 5 Pa.
  • the medium vacuum means a pressure range from 100 to 0.1 Pa.
  • the low vacuum means a pressure range from a pressure lower than the atmospheric pressure to 100 Pa.
  • an ultrahigh vacuum means a pressure range from 10 ⁇ 5 to 10 ⁇ 8 Pa.
  • An extrahigh vacuum means a pressure lower than 10 ⁇ 8 Pa.
  • a vacuum that can be created on the earth is about 10 ⁇ 10 Pa at present.
  • the first vacuum pump and the second vacuum pump are integrally connected to each other, and hence it is possible for the user to evacuate a gas in a container to an ultrahigh vacuum by a single pump system. Since the first vacuum pump for evacuating a gas in the container to a high vacuum or less and the second vacuum pump for evacuating the gas in the container from an atmospheric pressure to a medium or low vacuum are combined with each other, it is possible for the respective pumps to consume appropriate amounts of power respectively in the medium vacuum range and the ultrahigh vacuum range.
  • a pump system that does not essentially operate in a low evacuation efficiency state, i.e., a state where evacuation in the ultrahigh vacuum range is performed by a single pump comprising a positive vacuum pump or a state where evacuation in the atmospheric pressure range is performed by a single pump comprising a kinetic vacuum pump.
  • the expression “the first vacuum pump and the second vacuum pump are integrally connected to each other into an integral unit” means that the first vacuum pump and the second vacuum pump are coupled and integrated into a physically single pump unit.
  • a controller for controlling the whole pumps in the vacuum evacuation apparatus may be mounted on the pump unit or may be installed in the vicinity of the pump unit.
  • the first vacuum pump and the second vacuum pump may be directly coupled or a coupling member may be provided between the first vacuum pump and the second vacuum pump.
  • the first vacuum pump has a rotational shaft and the second vacuum pump has a rotational shaft, and the rotational shaft of the first vacuum pump and the rotational shaft of the second vacuum pump have respective axes which are perpendicular to each other.
  • the first vacuum pump and the second vacuum pump When the first vacuum pump and the second vacuum pump are in operation, they produce vibrations in substantially the same directions, i.e., their vibrational energies are intensive in substantially the same directions. Specifically, the first vacuum pump and the second vacuum pump produce vibrations due to unbalanced rotating bodies in the radial directions of their rotational shafts. If the rotational shaft of the second vacuum pump and the rotational shafts of the first vacuum pump in the unitized vacuum evacuation apparatus according to the present invention are disposed parallel to each other, then it is possible for the second vacuum pump and the first vacuum pump to simultaneously produce rotary vibrations in the radial directions perpendicular to the axes of the rotational shafts, causing resonant vibrations and causing impairment of pump mechanical components.
  • the axes of the rotational shafts of the first vacuum pump and the axis of the rotational shaft of the second vacuum pump extend perpendicularly to each other, thereby minimizing radial vibrations generated by the rotational shaft of the first vacuum pump that is attached to the vacuum container.
  • the first vacuum pump has a rotational shaft and the second vacuum pump has a rotational shaft
  • the rotational shaft of the first vacuum pump and the rotational shaft of the second vacuum pump are rotatably supported by one of self-lubricating bearings, bearings having a semi-solid lubricant or a solid lubricant therein, gas bearings, and magnetic bearings; and wherein the rotational shaft of the first vacuum pump and the rotational shaft of the second vacuum pump are rotatable regardless of directions in which the first vacuum pump and the vacuum pump are installed.
  • the bearings that support the rotational shaft of the first vacuum pump and the bearings that support the rotational shafts of the second vacuum pump may comprise rolling bearings made of a self-lubricating material or including grease in roller races, self-lubricating journal bearings, or non-contact bearings such as gas bearings or magnetic bearings. These bearings allow the rotational shafts to rotate in stable conditions regardless of mounting directions of the vacuum evacuation apparatus. Since the vacuum evacuation apparatus according to the present invention has an appearance as a single pump unit, the user does not usually think that it contains the first vacuum pump and the second vacuum pump combined together.
  • the dry vacuum pumps used generally for a second vacuum pump uses low-viscosity lubricating oil such as mineral oil to lubricate the bearings, and hence has certain limitations on the mounting directions thereof.
  • the turbomolecular pump has its rotational shaft rotatably supported by ball bearings that are lubricated mainly by grease, or non-contact bearings, so that the turbomolecular pump is free of limitations with respect to directions in which it is mounted.
  • the dry vacuum pump according to the present invention uses the bearings which can support the rotational shafts without using low-viscosity lubricating oil such as mineral oil, and thus does not pose limitations on the mounting directions of the pump unit.
  • the first vacuum pump has a bottom component and the second vacuum pump has a casing, and the bottom component and the casing are integrally connected to each other, thereby integrally connecting the first vacuum pump and the second vacuum pump.
  • the bottom component of the first vacuum pump and the pump casing of the second vacuum pump are integrated into a common part, and an evacuation passage is provided in the common part to allow the first vacuum pump and the second vacuum pump to communicate with each other.
  • the evacuation path of the two pumps By incorporating the evacuation path of the two pumps into the common part, the evacuation path of the two pumps can be shortened to increase the conductance of the pump unit, and the volume of the second vacuum pump can be reduced. Then, the cost of the entire pump unit can be further reduced and the volume taken up by the entire pump unit can be reduced.
  • the bottom component and the pump casing are integrated, thermal conductivity of the two pumps can be improved.
  • the second vacuum pump which compresses a gas up to the atmospheric pressure consumes more electric power and generates more heat than the first vacuum pump at the ultrahigh vacuum side. If the second vacuum pump is cooled by cooling water, the increased thermal conductivity between the two pumps allows only a cooling mechanism incorporated in the first vacuum pump to cool the two pumps efficiently (to radiate heat from the two pumps efficiently).
  • the first vacuum pump and the second vacuum pump are integrally connected to each other through a heat insulation member or a small area of contact.
  • the second vacuum pump is not cooled by cooling water, then in order to lower the thermal conductivity between the fastening surfaces of the first vacuum pump and the second vacuum pump, it is effective to combine a thermal insulation with the fastening portion or to reduce the cross-sectional area of a contacting region of the fastening portion, or both to combine a thermal insulation with the fastening portion and to reduce the cross-sectional area of a contacting region of the fastening portion.
  • the second vacuum pump is not cooled by cooling water, then it is forcedly air-cooled.
  • the second vacuum pump which compresses a gas up to the atmospheric pressure consumes more electric power and generates more heat than the first vacuum pump. If the second vacuum pump is forcedly air-cooled, its exhaust heat performance is much lower than the cooling water.
  • the thermal conductivity between the two pumps is high, the heat may be transferred from the second vacuum pump to the first vacuum pump, possibly impairing the normal operation of the first vacuum pump. Therefore, by providing the heat insulation member at the connecting portion of the two pumps or making the contact area of the connecting portion small, the thermal conductivity between the two pumps is lowered to minimize the heat transfer from the second vacuum pump to the first vacuum pump.
  • the first vacuum pump and the second vacuum pump are integrally connected to each other through a vibro-isolating mechanism.
  • the second vacuum pump which compresses a gas up to the atmospheric pressure vibrates to an extent greater than the first vacuum pump. If vibrations of the vacuum evacuation apparatus of the present invention which integrates the first vacuum pump and the second vacuum pump are large, the vacuum evacuation apparatus cannot be installed in the vicinity of the vacuum container. Therefore, the vibro-isolating mechanism for isolating vibrations from the second vacuum pump is provided at the connecting portion of the first vacuum pump and the second vacuum pump, and thus any vibrations that are transmitted from the second vacuum pump to the first vacuum pump can be reduced.
  • the vibro-isolating mechanism may comprise a vibro-isolating rubber (natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.) which has a Young's modulus equal to or smaller than 1000 KPa (1000 to 10 KPa) and an Asker C hardness level equal to or smaller than 50 (50 to 4), or may comprise a spring.
  • a vibro-isolating rubber natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.
  • the vibro-isolating mechanism may comprise a vibro-isolating rubber (natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.) which has a Young's modulus equal to or smaller than 1000 KPa (1000 to 10 KPa) and an Asker C hardness level equal to or smaller than 50 (50 to 4), or may comprise a spring.
  • the first vacuum pump has an outlet port and the second vacuum pump has an inlet port, and the outlet port and the inlet port are interconnected by an evacuation passage component comprising a vibro-isolating material.
  • the evacuation passage component may transmit vibrations from the second vacuum pump to the first vacuum pump. Since the evacuation passage component is made of a vibro-isolating material, it can minimize vibrations transmitted from the second vacuum pump to the first vacuum pump.
  • the vibro-isolating material may be a rubber material (natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.) which has a Young's modulus equal to or smaller than 1000 KPa (1000 to 10 KPa) and an Asker C hardness level equal to or smaller than 50 (50 to 4), and may be in the shape of a tube or a block.
  • the first vacuum pump has an inlet port and the second vacuum pump has an inlet port, and the inlet port of the first vacuum pump and the inlet port of the second vacuum pump are interconnected by a bypass passage for bypassing the first vacuum pump.
  • the bypass pipe which interconnects the inlet port of the first vacuum pump and the inlet of the second vacuum pump is provided.
  • the bypass pipe serves to directly discharge a gas from the inlet port of the first vacuum pump into the inlet of the second vacuum pump, thereby bypassing the first vacuum pump. Consequently, even when the vacuum in the vacuum container breaks, a sudden load buildup can be prevented from being exerted on the first vacuum pump, and hence the rotating body of the first vacuum pump can be protected against damage.
  • the first vacuum pump has an outlet port and the second vacuum pump has an inlet port, and the outlet port and the inlet port are interconnected by an evacuation passage component incorporating therein a check valve for preventing a fluid from flowing back from the second vacuum pump to the first vacuum pump while the first vacuum pump is in operation.
  • the first vacuum pump and the second vacuum pump are integrally connected together into an integral pump unit including the evacuation passage component therein. Therefore, the pressure conditions for the evacuation passage component are known.
  • one of the first and second vacuum pumps fails to operate, e.g., when the second vacuum pump becomes faulty in operation, the back pressure of the first vacuum pump increases suddenly.
  • the check valve which automatically closes under the differential pressure in the evacuation passage component, the pressure at the exhaust side of the first vacuum pump can be prevented from abruptly rising.
  • a controller for controlling the first vacuum pump and the second vacuum pump wherein the controller is integrally connected to the first vacuum pump or is installed separately from the first vacuum pump.
  • the controller when each of the first vacuum pump and the second vacuum pump reaches a rated rotational speed and no gas is introduced into the container, the controller lowers a voltage applied to a motor of at least one of the first vacuum pump and the second vacuum pump and continuously operates the motor at a motor maximum efficient point.
  • the controller is capable of controlling the pressure in the container at a target pressure level by individually controlling respective rotational speeds of the first vacuum pump and the second vacuum pump depending on flow rates of the gas evacuated therefrom.
  • the evacuation rate of a pump is controlled by adjusting the opening area of the suction side with a control valve or the like.
  • the pressure in the vacuum container to be evacuated is controlled by controlling at least one of the rotational speed of the first vacuum pump and the rotational speed of the second vacuum pump, rather than by adjusting the opening (opening area) of a valve disposed between the vacuum container and the pump.
  • the evacuation rate of each of the vacuum pumps is adjusted to adjust the overall evacuation rate of the pump system as the vacuum evacuation apparatus.
  • the pressure in the vacuum container can be controlled by the single pump system without the need for a control valve other than the vacuum pumps.
  • the second vacuum pump comprises a dry vacuum pump having a pair of pump rotors with respective magnet rotors mounted thereon, the magnet rotors have equal numbers of magnetic poles and are disposed so that their different magnetic poles are magnetically attracted to each other, and currents supplied to a multiphase armature including an iron core and a plurality of windings disposed radially outwardly of at least one of the magnet rotors are switched to actuate the at least one of the magnet rotors for thereby rotating the pump rotors in opposite directions in synchronism with each other.
  • the dual-shaft pump rotors can be rotated synchronously in the opposite directions by a simple structural motor having permanent magnets and windings for rotating the permanent magnets. Therefore, any timing gears for synchronizing the dual-shaft pump rotors are not required, and oil-free, low vibrations and low noise can be realized. If lubricating oil is used to lubricate the bearings and timing gears, the lubricating oil leaks out when the pump is tilted, and hence mounting posture of the pump is limited. However, the oil-free pump according to the present invention can be mounted in a posture that can freely be selected, and does not produce significant vibrations and noise caused by contact of the timing gears.
  • the dry vacuum pump having the above structure is used as the second vacuum pump, any vibrations that are transmitted from the second vacuum pump to the first vacuum pump can be suppressed, and thus the second vacuum pump can be integrally coupled to the first vacuum pump.
  • the second vacuum pump can be mounted at a freely selectable posture.
  • the integral unit of the first vacuum pump and the second vacuum pump is attached to an object to be evacuated, e.g., a vacuum container (vacuum chamber), the integral unit can be mounted at a freely selectable posture.
  • the first vacuum pump and the second vacuum pump are integrally connected to each other by at least one evacuation passage.
  • the plural second vacuum pumps are integrally connected to the single first vacuum pump, it is possible to construct a roughening pump system having an evacuation capacity which matches the evacuation capacity of the first vacuum pump. Since the plural second vacuum pumps can be controlled in parallel for controlling the pressure in the vacuum container, the pressure in the vacuum container can be controlled more appropriately. Further, even if one of the second vacuum pumps fails to operate, the other second vacuum pump can back up the first vacuum pump. Therefore, even if one of the second vacuum pumps shuts down, a situation where the first vacuum pump shuts down to cause a quick pressure buildup in the vacuum container can be avoided.
  • a plurality of the first vacuum pumps may be integrally connected to a single second vacuum pump. With this arrangement, the rotor of each of the first vacuum pumps can be reduced in size. Two or three vacuum pumps that are integrally connected to each other can be controlled by a single controller.
  • the first vacuum pump and the second vacuum pump By using the combination of the above dimension and volume ratios for the first vacuum pump and the second vacuum pump, it is possible to integrally connect a plurality of second vacuum pumps to the first vacuum pump which has an evacuation capacity that is several times greater than each of the second vacuum pumps.
  • ultrahigh vacuum evacuation can be performed by a single pump system. Further, by a combination of the first vacuum pump for evacuating the container to a high vacuum or less and the second vacuum pump for evacuating the container from an atmospheric pressure to a medium or low vacuum, the pumps can evacuate the container respectively to the medium vacuum range and the ultrahigh vacuum range by appropriate respective consumed power, and the consumed power of the whole system can be reduced.
  • the second vacuum pump as an auxiliary pump can be integrally coupled to the first vacuum pump, the installation space (footprint) of the auxiliary pump can be reduced.
  • the second vacuum pump can be mounted at a freely selectable posture. Furthermore, when the integral unit of the first vacuum pump and the second vacuum pump is attached to an object to be evacuated, e.g., a vacuum container (vacuum chamber), the integral unit can be mounted at a freely selectable posture.
  • a vacuum container vacuum chamber
  • FIG. 1A is a front elevational view, partly in cross section, of a vacuum evacuation apparatus according to a first aspect of the present invention
  • FIG. 1B is a side elevational view, partly in cross section, of the vacuum evacuation apparatus shown in FIG. 1A ;
  • FIG. 2 is a schematic cross-sectional view showing structural details of a first vacuum pump of the vacuum evacuation apparatus shown in FIG. 1A ;
  • FIG. 3 is a schematic cross-sectional view showing structural details of a second vacuum pump of the vacuum evacuation apparatus shown in FIG. 1A ;
  • FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3 ;
  • FIG. 5A is a front elevational view, partly in cross section, of the vacuum evacuation apparatus with the second vacuum pump being installed at another posture;
  • FIG. 5B is a side elevational view, partly in cross section, of the vacuum evacuation apparatus shown in FIG. 5A ;
  • FIG. 5C is a bottom view, partly in cross section, of the vacuum evacuation apparatus shown in FIG. 5A ;
  • FIGS. 6A and 6B are front elevational views of the vacuum evacuation apparatus with a controller mounted on the first vacuum pump in different positions;
  • FIGS. 7A and 7B are schematic cross-sectional views showing a vacuum evacuation apparatus in which a bottom component of the first vacuum pump and a pump casing of the second vacuum pump are integrally joined to each other;
  • FIG. 8 is a schematic front elevational view, partly in cross section, of a vacuum evacuation apparatus in which a vibro-isolating mechanism is provided between the first vacuum pump and the second vacuum pump
  • FIG. 9 is a schematic front elevational view, partly in cross section, of a vacuum evacuation apparatus in which a fastening component for fastening the first vacuum pump and the second vacuum pump is combined with a vibro-isolating mechanism;
  • FIG. 10A is a cross-sectional view of the structure of a fastening assembly comprising the fastening component and vibro-isolating bushings shown in FIG. 9 ;
  • FIG. 10B is a bottom view of the fastening assembly shown in FIG. 10A ;
  • FIG. 10C is an exploded perspective view of one of the vibro-isolating bushings shown in FIG. 10A ;
  • FIGS. 11A and 11B are front elevational views of a pump unit (vacuum evacuation apparatus) having a first vacuum pump and a second vacuum pump that are integrally mounted on a vacuum container (vacuum chamber);
  • FIG. 12A is a front elevational view, partly in cross section, of a vacuum evacuation apparatus with a second vacuum pump mounted on a side surface of a first vacuum pump;
  • FIG. 12B is a bottom view of the vacuum evacuation apparatus with the second vacuum pump mounted on the side surface of the first vacuum pump;
  • FIGS. 13A and 13B are a front elevational view, partly in cross section, and a bottom view of a vacuum evacuation apparatus with a second vacuum pump mounted on a side surface of a first vacuum pump, the first vacuum pump and the second vacuum pump being fastened to each other by a fastening component combined with a vibro-isolating mechanism;
  • FIG. 13C is a cross-sectional view showing structural details of a fastening assembly of the vacuum evacuation apparatus shown in FIGS. 13A and 13B ;
  • FIG. 14 is a schematic front elevational view of a vacuum evacuation apparatus including a first vacuum pump, a second vacuum pump, and a check valve disposed in a evacuation passage component which interconnects an outlet port of the first vacuum pump and an inlet port of the second vacuum pump;
  • FIG. 15 is a schematic front elevational view of a vacuum evacuation apparatus including a first vacuum pump, a second vacuum pump, and a bypass pipe interconnecting an inlet port of the first vacuum pump and an inlet port of the second vacuum pump for bypassing the first vacuum pump;
  • FIG. 16 is a set of graphs showing comparison results in which the rotational speeds of first and second vacuum pumps were changed to adjust the pressure in a vacuum container in a pump rotational speed control process which was performed on a vacuum evacuation apparatus according to the present invention and a vacuum evacuation apparatus according to the related art, in the case of the first vacuum pump comprising a turbomolecular pump and the second vacuum pump comprising a dry pump;
  • FIG. 17 is a schematic front elevational view, partly in cross section, of a vacuum evacuation apparatus according to an embodiment of the present invention which includes a single first vacuum pump and a plurality of second vacuum pumps integrally connected to the first vacuum pump;
  • FIG. 18 is a schematic front elevational view, partly in cross section, of a vacuum evacuation apparatus according to an embodiment of the present invention which includes a single first vacuum pump and a plurality of second vacuum pumps integrally connected to the first vacuum pump by inlet and outlet passages;
  • FIG. 19 is a schematic front elevational view, partly in cross section, of a vacuum evacuation apparatus according to an embodiment of the present invention which includes a plurality of first vacuum pumps and a single second vacuum pump integrally connected to the first vacuum pumps by inlet and outlet passages;
  • FIG. 20 is a block diagram of a control circuit for controlling a vacuum evacuation apparatus including two first vacuum pumps and a single second vacuum pump which are integrally connected;
  • FIG. 21 is a graph showing how the rotational speeds of a single first vacuum pump and two second vacuum pumps were changed to adjust the pressure in a vacuum container in a pump rotational speed control process which was performed on a vacuum evacuation apparatus according to the present invention, in the case of the first vacuum pump comprising a turbomolecular pump and the two second vacuum pumps comprising a dry pump;
  • FIG. 22 is a cross-sectional view of a turbomolecular pump for use in a vacuum evacuation apparatus according to the present invention.
  • FIG. 23 is a cross-sectional view of another turbomolecular pump for use in a vacuum evacuation apparatus according to the present invention.
  • FIG. 24 is a cross-sectional view of still another turbomolecular pump for use in a vacuum evacuation apparatus according to the present invention.
  • FIG. 25 is a cross-sectional view of yet another turbomolecular pump for use in a vacuum evacuation apparatus according to the present invention.
  • FIGS. 1A through 25 A vacuum evacuation apparatus according to preferred embodiments of the present invention will be described in detail below with reference to FIGS. 1A through 25 .
  • Identical or corresponding parts are denoted by identical or corresponding reference characters throughout views.
  • FIGS. 1A , 1 B and 1 C are views showing a vacuum evacuation apparatus according to a first aspect of the present invention
  • FIG. 1A is a front elevation view, partly in cross section
  • FIG. 1B is a side elevational view, partly in cross section
  • FIG. 1C is a bottom view, partly in cross section.
  • a vacuum evacuation apparatus is configured to evacuate a vacuum container (vacuum chamber) from an atmospheric pressure to an ultrahigh vacuum range.
  • the vacuum evacuation apparatus comprises a first vacuum pump 1 capable of evacuating the container to a high vacuum or less and a second vacuum pump 2 capable of evacuating the container to a pressure ranging from an atmospheric pressure to a medium or low vacuum.
  • the first vacuum pump 1 and the second vacuum pump 2 are unitized as an integral apparatus. Specifically, the first vacuum pump 1 and the second vacuum pump 2 are coupled together into an integral unit.
  • the first vacuum pump 1 comprises a turbomolecular pump
  • the second vacuum pump 2 comprises a dry vacuum pump.
  • An outlet port of the first vacuum pump 1 and an inlet port of the second vacuum pump 2 are interconnected by an evacuation passage component 3 .
  • a positive displacement pump e.g., dry pump
  • a turbomolecular pump as a first vacuum pump
  • the second vacuum pump for evacuating the container to a medium vacuum
  • the first vacuum pump e.g., turbomolecular pump
  • the first vacuum pump 1 comprising a turbomolecular pump and the second vacuum pump 2 comprising a dry vacuum pump are integrated and unitized.
  • the user can construct and perform ultrahigh vacuum evacuation in a container by a single pump system.
  • the turbomolecular pump and the dry vacuum pump the pumps can evacuate the container respectively to the medium vacuum range and the ultrahigh vacuum range by appropriate respective consumed power. Therefore, according to the present invention, there is provided a pump system that does not essentially operate in a low evacuation efficiency state, i.e., a state where evacuation in the ultrahigh vacuum range is performed by a single pump comprising a positive vacuum pump or a state where evacuation in the atmospheric pressure range is performed by a single pump comprising a kinetic vacuum pump.
  • the expression “the first vacuum pump 1 and the second vacuum pump 2 are coupled together into an integral unit” means that the first vacuum pump 1 and the second vacuum pump 2 are coupled and integrated into a physically single pump unit, as shown in FIG. 1A .
  • a controller for controlling the whole pumps in the vacuum evacuation apparatus may be mounted on the pump unit or may be installed in the vicinity of the pump unit.
  • the second vacuum pump 2 comprises a screw-type dry vacuum pump having a pair of screw rotors 52 a , 52 b rotatably disposed in a pump casing (described below).
  • FIG. 2 is a schematic cross-sectional view showing structural details of the first vacuum pump 1 of the vacuum evacuation apparatus shown in FIGS. 1A through 1C .
  • the multistage stator blades 14 are held between spacers 15 stacked in the pump casing 9 and are fixed in the pump casing 9 .
  • the turbine blades 11 as rotor blades and the stator blades 14 are alternately disposed in the turbine blade pumping assembly 10 .
  • the bearing motor assembly 30 comprises a motor 31 for applying rotational drive forces to the rotational shaft 13 , an upper radial magnetic bearing 32 for radially supporting the rotational shaft 13 , a lower radial magnetic bearing 33 for radially supporting the rotational shaft 13 , and a thrust magnetic bearing 34 for canceling thrust forces generated by the pressure difference developed between the inlet side and the outlet side by evacuation operation of the evacuation assembles.
  • the motor 31 comprises a high-frequency motor.
  • Each of the upper radial magnetic bearing 32 , the lower radial magnetic bearing 33 , and the thrust magnetic bearing 34 comprises an active magnetic bearing.
  • the pump casing 9 has an upper flange 9 uf on its upper end.
  • the inlet port SP is defined radially inwardly of the upper flange 9 uf .
  • a vacuum container (vacuum chamber) to be evacuated by the vacuum evacuation apparatus is connected to the upper flange 9 uf .
  • the base 26 of the stator 25 has a flange 26 f , and the outlet port DP is defined radially inwardly of the flange 26 f .
  • the evacuation passage component 3 (see FIG. 1 ) is connected to the flange 26 f , and the first vacuum pump 1 comprising a turbomolecular pump communicates with the second vacuum pump 2 by the evacuation passage component 3 .
  • small clearances are defined between outer circumferential surfaces of the screw rotors 52 a , 52 b and an inner circumferential surface of the pump casing 50 , allowing the screw rotors 52 a , 52 b to rotate out of contact with the pump casing 50 .
  • the screw rotors 52 a , 52 b have mutually confronting regions where the right- and left-hand screw threads loosely mesh with each other to allow the screw rotors 52 a , 52 b to rotate out of contact with each other.
  • Magnet rotors 54 are fixed respectively to ends of the rotational shafts 51 a , 51 b .
  • the pump casing 50 has an inlet port SP and an outlet port DP that are formed in a side wall thereof which lies parallel to the sheet of FIG. 3 .
  • the inlet port SP of the second vacuum pump 2 is connected to the outlet port DP of the first vacuum pump 1 by the evacuation passage component 3 (see FIG. 1 ).
  • the bearings 53 which are remote from the magnet rotors 54 are fixed to the pump casing 50 , and the other bearings 53 which are close to the magnet rotors 54 are fixed to a bearing housing 55 and a bearing holder 56 .
  • the bearing housing 55 is fixed to the pump casing 50 , and the bearing holder 56 is fixed to the bearing housing 55 .
  • the windings 57 b in the phases that are denoted by U 1 , V 1 , W 1 , U 1 ′, V 1 ′, W 1 ′, and the iron cores 57 a of the armatures 57 , and the magnet rotors 54 jointly make up a dual-shaft synchronous brushless DC motor.
  • the windings 57 b in the phases U 1 ′, V 1 ′, W 1 ′ are coiled in the opposite direction to the windings 57 b in the phases U 1 , V 1 , W 1 .
  • the screw-type dry vacuum pump having the above structure is used as the second vacuum pump 2 , any vibrations that are transmitted from the second vacuum pump 2 to the first vacuum pump 1 can be suppressed, and thus the second vacuum pump 2 can be integrally coupled to the first vacuum pump 1 .
  • the second vacuum pump 2 can be mounted at a freely selectable posture.
  • the integral unit of the first vacuum pump 1 and the second vacuum pump 2 is attached to an object to be evacuated, e.g., a vacuum container (vacuum chamber), the integral unit can be mounted at a freely selectable posture.
  • FIGS. 5A , 5 B and 5 C are views showing another examples of mounting postures in the case where the second vacuum pump 2 is mounted on the first vacuum pump 1
  • FIG. 5A is a front elevational view, partly in cross section
  • FIG. 5B is a side elevational view, partly in cross section
  • FIG. 5C is a bottom view, partly in cross section.
  • the first vacuum pump 1 comprising a turbomolecular pump and the second vacuum pump 2 comprising a dry vacuum pump are integrally connected together into an integral unit, and the second vacuum pump 2 have respective rotational shafts whose axes lying perpendicularly to the axis of the rotational shaft of the first vacuum pump 1 .
  • the dry vacuum pump and the turbomolecular pump When the dry vacuum pump and the turbomolecular pump are in operation, they produce vibrations in substantially the same directions, i.e., their vibrational energies are intensive in substantially the same directions. Specifically, the dry vacuum pump and the turbomolecular pump produce vibrations due to unbalanced rotating bodies in the radial directions of their rotational shafts. If the rotational shaft of the turbomolecular pump and the rotational shafts of the dry vacuum pump in the unitized vacuum evacuation apparatus according to the present invention are disposed parallel to each other, then it is possible, though very small probability, for the turbomolecular pump and the dry vacuum pump to simultaneously produce rotary vibrations in the radial directions perpendicular to the axes of the rotational shafts, causing resonant vibrations.
  • the axes of the rotational shafts of the dry vacuum pump and the axis of the rotational shaft of the turbomolecular pump extend perpendicularly to each other, thereby minimizing radial vibrations generated by the rotational shaft of the first vacuum pump that is attached to the vacuum container.
  • the bearings that support the rotational shaft of the first vacuum pump 1 and the bearings that support the rotational shafts of the second vacuum pump 2 may comprise rolling bearings made of a self-lubricating material or including grease in roller races, self-lubricating journal bearings, or non-contact bearings such as gas bearings or magnetic bearings. These bearings allow the rotational shafts to rotate in stable conditions regardless of mounting directions of the vacuum evacuation apparatus. Since the vacuum evacuation apparatus according to the present invention has an appearance as a single pump unit, the user does not usually think that it contains the dry vacuum pump and the turbomolecular pump combined together. General dry vacuum pumps use low-viscosity lubricating oil such as mineral oil to lubricate the bearings, and hence have certain limitations on the mounting directions thereof.
  • the first vacuum pump 1 and the second vacuum pump 2 have respective actuators, i.e., motors.
  • actuators i.e., motors.
  • common components can be used to construct a single controller, thus downsizing the controller and reducing the cost of the controller, compared to the respective controllers.
  • the controller should preferably installed on the first vacuum pump. Specifically, the dry vacuum pump is heated up to a higher temperature than the turbomolecular pump because of the heat generated when the dry vacuum pump compresses a gas up to the atmospheric pressure.
  • the turbomolecular pump has a vibration level much lower than the positive displacement dry vacuum pump.
  • the controller having a number of electronic precision components should be installed on the turbomolecular pump, rather than the dry vacuum pump, as the turbomolecular pump is less liable to exert unwanted thermal and vibrational effects on the controller.
  • the controller thus installed is effective to increase the overall reliability of the pump unit.
  • FIGS. 6A and 6B are front elevational views showing a vacuum evacuation apparatus with a controller 4 installed on the first vacuum pump 1 .
  • the controller 4 is attached to an outer circumferential surface of the first vacuum pump 1 .
  • the controller 4 is attached to a lower surface of the first vacuum pump 1 .
  • the controller 4 may be attached to the first vacuum pump 1 through a mount portion incorporating a vibro-isolating mechanism therein.
  • the vibro-isolating mechanism may comprise a vibro-isolating rubber (natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.) or a spring.
  • the controller 4 is installed on the first vacuum pump 1 .
  • the controller 4 may be installed in any selected position spaced from the first vacuum pump 1 .
  • FIGS. 7A and 7B are cross-sectional views showing embodiments in which a bottom component of the first vacuum pump 1 and a pump casing of the second vacuum pump 2 are integrally joined to each other.
  • a bottom component 40 of the first vacuum pump 1 and a pump casing 50 of the second vacuum pump 2 are integrally joined to each other to form an integral unit 60 .
  • a bottom component 40 of the first vacuum pump 1 and a pump casing 50 of the second vacuum pump 2 are integrally joined to each other to form an integral unit 60 which has an evacuation passage 3 a defined therein which provides fluid communication between the first vacuum pump 1 and the second vacuum pump 2 .
  • the bottom component 40 and the pump casing 50 are integrated into a common part, so that the number of parts used is reduced and hence the cost thereof is reduced, and the overall unit takes up a reduced volume.
  • the integral unit 60 may incorporate the evacuation passage 3 a for the two pumps. If the evacuation path of the two pumps can be shortened, the conductance of the pump unit is increased, and the volume of the second vacuum pump 2 can be reduced. Then, the cost of the entire pump unit can be further reduced and the volume taken up by the entire pump unit can be reduced. Furthermore, since the bottom component 40 and the pump casing 50 are integrated, thermal conductivity of the two pumps can be improved.
  • the second vacuum pump 2 which compresses a gas up to the atmospheric pressure consumes more electric power and generates more heat than the first vacuum pump 1 at the ultrahigh vacuum side. If the second vacuum pump 2 is cooled by cooling water, the increased thermal conductivity between the two pumps allows only a cooling mechanism incorporated in the first vacuum pump 1 to cool the two pumps efficiently (to radiate heat from the two pumps efficiently).
  • the second vacuum pump 2 is not cooled by cooling water, then in order to lower the thermal conductivity between the fastening surfaces of the first vacuum pump 1 and the second vacuum pump 2 , it is effective to combine a thermal insulation with the fastening portion or to reduce the cross-sectional area of a contacting region of the fastening portion, or both to combine a thermal insulation with the fastening portion and to reduce the cross-sectional area of a contacting region of the fastening portion. If the second vacuum pump 2 is not cooled by cooling water, then it is forcedly air-cooled. As described above, the second vacuum pump 2 which compresses a gas up to the atmospheric pressure consumes more electric power and generates more heat than the first vacuum pump 1 .
  • the second vacuum pump 2 If the second vacuum pump 2 is forcedly air-cooled, its exhaust heat performance is much lower than the cooling water. If the thermal conductivity between the two pumps is high, the heat may be transferred from the second vacuum pump 2 to the first vacuum pump 1 , possibly impairing the normal operation of the first vacuum pump 1 . Consequently, the thermal conductivity between the two pumps is lowered to minimize the heat transfer from the second vacuum pump 2 to the first vacuum pump 1 .
  • An air-cooling fan that is designed to match the cross-sectional area of the second vacuum pump 2 is used to locally air-cool the second vacuum pump 2 to discharge the heat therefrom.
  • the thermal insulation material may be ceramics (alumina, yttria, zirconia, etc.), stainless steel alloy, or plastics (PEEK, PTFE, etc.).
  • FIG. 8 is a schematic front elevation view showing an embodiment in which a vibro-isolating mechanism 61 is provided between fastening surfaces of the first vacuum pump 1 and the second vacuum pump 2 .
  • the screw rotors 52 a , 52 b of the second vacuum pump 2 are capable of rotating in opposite directions in synchronism with each other because of a magnetic coupling between the magnet rotors 54 , the second vacuum pump 2 does not need any timing gears for synchronizing the two screw rotors 52 a , 52 b , so that any vibrations of the second vacuum pump 2 are greatly reduced.
  • the vibro-isolating mechanism 61 for isolating vibrations from the second vacuum pump 1 is provided at the fastening portion of the first vacuum pump 1 and the second vacuum pump 2 , and thus any vibrations that are transmitted from the second vacuum pump 2 to the first vacuum pump 1 can be reduced.
  • the vibro-isolating mechanism 61 may comprise a vibro-isolating rubber (natural rubber, nitrile rubber, silicone rubber, fluoro rubber, etc.) or a spring.
  • the evacuation passage component 3 interconnecting the outlet port of the first vacuum pump 1 and the inlet port of the second vacuum pump 2 is made of a vibro-isolating material. If the evacuation passage component 3 is made of a highly rigid material or has a highly rigid structure, then it may transmit vibrations from the second vacuum pump 2 to the first vacuum pump 1 . Since the evacuation passage component 3 is made of a vibro-isolating material, it can minimize vibrations transmitted from the second vacuum pump 2 to the first vacuum pump 1 .
  • the vibro-isolating material may be a rubber material such as natural rubber, nitrile rubber, silicone rubber or fluoro rubber, and may be in the shape of a tube or a block.
  • the evacuation passage component 3 When a vacuum is created in the evacuation passage component 3 which is made of a vibro-isolating material such as rubber, it tends to be deformed under the differential pressure between the pressure in the evacuation passage component 3 and the atmospheric pressure.
  • a helical spring of metal may be placed in the evacuation passage component 3 to prevent the evacuation passage component 3 from being deformed.
  • the helical spring thus placed in the evacuation passage component 3 does not prevent the evacuation passage component 3 from being bent or curved.
  • the length of the helical spring may be determined as desired relative to the length of the evacuation passage component 3 .
  • FIG. 9 is a schematic side elevational view showing an embodiment in which the first vacuum pump 1 and the second vacuum pump 2 are fastened to each other by a fastening component combined with a vibro-isolating mechanism.
  • a fastening component 62 is disposed between the first vacuum pump 1 and the second vacuum pump 2 .
  • a plurality of vibro-isolating bushings 63 are mounted on the fastening component 62 .
  • the fastening component 62 is fixed to the first vacuum pump 1 by fastening bolts 64 that are threaded through the respective vibro-isolating bushings 63 into the first vacuum pump 1 .
  • the fastening component 62 has an evacuation passage 62 a defined therein which is held in fluid communication with the inlet port SP of the second vacuum pump 2 and an evacuation passage 62 b defined therein which is held in fluid communication with the outlet port DP of the second vacuum pump 2 .
  • the evacuation passage 62 a of the fastening component 62 is connected to the outlet port DP (see FIG. 2 ) of the first vacuum pump 1 by an evacuation passage component 3 .
  • the evacuation passage 62 b of the fastening component 62 serves to vent the outlet port DP of the second vacuum pump 2 to the atmosphere.
  • the evacuation passage component 3 is made of a vibro-isolating material such as rubber or the like.
  • FIGS. 10A , 10 B and 10 C are views showing the structure of a fastening assembly comprising the fastening component 62 and the vibro-isolating bushings 63 .
  • FIG. 10A is a cross-sectional view of the fastening assembly
  • FIG. 10B is a bottom view of the fastening assembly
  • FIG. 10C is an exploded perspective view of one of the vibro-isolating bushings 63 .
  • each of the vibro-isolating bushings 63 includes an upper member 63 a comprising a large-diameter ring-shaped portion and a small-diameter ring-shaped portion, and a lower member 63 b comprising a ring-shaped portion. As shown in FIG.
  • the upper member 63 a is mounted on the fastening component 62 in such a manner that the small-diameter ring-shaped portion is fitted in a circular hole defined by the inner circumferential surface of the flange 62 f of the fastening component 62 and the large-diameter ring-shaped portion having a lower surface is held against the upper surface of the flange 62 f .
  • the lower member 63 b is fitted over the outer circumferential surface of the small-diameter ring-shaped portion of the upper member 63 a and held against the lower surface of the flange 62 f .
  • the fitting surfaces of the upper member 63 a and the lower member 63 b are integrally united together by an adhesive bonding or the like, causing the upper member 63 a and the lower member 63 b to grip the flange 62 f of the fastening component 62 .
  • all the vibro-isolating bushings 63 are mounted in place on the fastening component 62 .
  • the fastening bolts 64 are inserted through the respective vibro-isolating bushings 63 , and threaded into the first vacuum pump 1 with washers 65 interposed between the heads of the fastening bolts 64 and the vibro-isolating bushings 63 . Therefore, the fastening component 62 is securely fastened to the first vacuum pump 1 with the vibro-isolating bushings 63 disposed therebetween.
  • the fastening component 62 and the second vacuum pump 2 are fastened to each other by bolts or the like.
  • FIGS. 11A and 11B are front elevation views showing embodiments in which a pump unit (vacuum evacuation apparatus) having the first vacuum pump 1 and the second vacuum pump 2 that are integrated is mounted on a vacuum container (vacuum chamber) 5 .
  • the pump unit (vacuum evacuation apparatus) shown in FIG. 1 is mounted on the vacuum container (vacuum chamber) 5 .
  • the pump unit which includes the first vacuum pump 1 and the second vacuum pump 2 that are integrally connected to each other is mounted on a lower surface of the vacuum container 5 with the axis of the first vacuum pump 1 extending vertically.
  • the axes of the screw rotors 52 a , 52 b of the second vacuum pump 2 are perpendicular to the axis of the first vacuum pump 1 .
  • the pump unit which includes the first vacuum pump 1 and the second vacuum pump 2 that are integrally connected to each other is mounted on a side surface of the vacuum container 5 with the axis of the first vacuum pump 1 extending horizontally.
  • the axes of the screw rotors 52 a , 52 b of the second vacuum pump 2 are perpendicular to the axis of the first vacuum pump 1 .
  • the pump unit which includes the first vacuum pump 1 and the second vacuum pump 2 that are integrally connected to each other may be mounted on an upper surface of the vacuum container 5 . Further, the pump unit which includes the first vacuum pump 1 and the second vacuum pump 2 that are integrally connected to each other as shown in FIGS. 5A through 5C may be mounted on the vacuum container 5 in the same mounting postures as those shown in FIGS. 11A and 11B .
  • FIGS. 12A and 12B are views showing a mounting posture in which the second vacuum pump 2 is mounted on a side surface of the first vacuum pump 1 , FIG. 12A is a side elevational view, partly in cross section and FIG. 12B is a bottom view.
  • the second vacuum pump 2 is mounted on a side surface of the first vacuum pump 1 .
  • the first vacuum pump 1 has a cylindrical pump casing with a flat cut surface on an outer circumferential surface thereof, and the second vacuum pump 2 is fixed to the flat cut surface.
  • the axis 1 x of the first vacuum pump 1 and the axes 52 ax , 52 bx of the respective screw rotors 52 a , 52 b of the second vacuum pump 2 are parallel to each other.
  • FIGS. 12A and 12B the embodiments shown in FIGS.
  • the rotational shaft of the first vacuum pump 1 and the rotational shafts of the second vacuum pump 2 are perpendicular to each other to prevent radial resonant vibrations from being produced.
  • the screw rotors 52 a , 52 b of the second vacuum pump 2 are capable of rotating in opposite directions in synchronism with each other because of a magnetic coupling between the magnet rotors 54 , the second vacuum pump 2 does not need any timing gears for synchronizing the two screw rotors 52 a , 52 b , so that any vibrations of the second vacuum pump 2 can be greatly reduced. Consequently, no significant radial resonant vibrations are not produced even though the rotational shaft of the first vacuum pump 1 and the rotational shafts of the second vacuum pump 2 are perpendicular to each other.
  • FIGS. 13A , 13 B and 13 C are views showing an embodiment in which the second vacuum pump 2 is mounted on a side surface of the first vacuum pump 1 , and the first vacuum pump 1 and the second vacuum pump 2 are fastened to each other by a fastening component combined with a vibro-isolating mechanism.
  • FIG. 13A is a side elevational view, partly in cross section, of the first vacuum pump 1 and the second vacuum pump 2
  • FIG. 13B is a bottom view, partly in cross section, of the first vacuum pump 1 and the second vacuum pump 2
  • FIG. 13C is a cross-sectional view showing structural details of a fastening assembly that fastens the first vacuum pump 1 and the second vacuum pump 2 shown in FIGS. 13A and 13B .
  • the second vacuum pump 2 is mounted on a side surface of the first vacuum pump 1 , and a fastening component 62 is disposed between the first vacuum pump 1 and the second vacuum pump 2 .
  • a plurality of vibro-isolating bushings 63 are mounted on the fastening component 62 .
  • the fastening component 62 is fixed to the first vacuum pump 1 by fastening bolts 64 that are threaded through the respective vibro-isolating bushings 63 into the first vacuum pump 1 .
  • the fastening component 62 , the vibro-isolating bushings 63 , and the fastening bolts 64 are identical in structure to those shown in FIGS. 10A through 10C , and are installed in position in the same manner as shown in FIGS. 10A through 10C .
  • FIG. 14 is a schematic front elevation view showing an embodiment in which a check valve 6 is provided in an evacuation passage component 3 which interconnects an outlet port of the first vacuum pump 1 and an inlet port of the second vacuum pump 2 .
  • the pump unit which includes the first vacuum pump 1 and the second vacuum pump 2 that are integrally connected to each other is mounted on the vacuum container 5 .
  • the check valve 6 is disposed in the evacuation passage component 3 which interconnects the outlet port of the first vacuum pump 1 and the inlet port of the second vacuum pump 2 .
  • the first vacuum pump 1 comprising a turbomolecular pump and the second vacuum pump 2 comprising a dry vacuum pump are integrally connected together into an integral pump unit including the evacuation passage component 3 therein. Therefore, the pressure conditions for the evacuation passage component 3 are known.
  • one of the first and second vacuum pumps 1 , 2 fails to operate, e.g., when the dry vacuum pump becomes faulty in operation, the back pressure of the turbomolecular pump increases suddenly.
  • the check valve 6 which automatically closes under the differential pressure in the evacuation passage component, the pressure at the exhaust side of the turbomolecular pump can be prevented from abruptly rising.
  • FIG. 15 is a schematic front elevation view showing an embodiment in which a bypass pipe 7 interconnecting the inlet port of the first vacuum pump 1 and the inlet of the second vacuum pump 2 is provided for bypassing the first vacuum pump 1 .
  • the bypass pipe 7 interconnects the inlet port of the first vacuum pump 1 and the inlet of the second vacuum pump 2 is provided.
  • the bypass pipe 7 serves to directly discharge a gas from the inlet port of the first vacuum pump 1 into the inlet of the second vacuum pump 2 , thereby bypassing the first vacuum pump 1 . Consequently, even when the vacuum in the vacuum container 5 breaks, a sudden load buildup can be prevented from being exerted on the first vacuum pump 1 , and hence the rotating body of the first vacuum pump can be protected against damage.
  • bypass valve 8 which is opened to connect the inlet port of the first vacuum pump 1 directly to the inlet of the second vacuum pump 2 is provided in the bypass pipe 7 in the event of an abrupt increase of the pressure in the vacuum container 5 .
  • the bypass valve 8 can be automatically opened and closed under pressure conditions in the bypass pipe 7 . Such pressure conditions can be established with ease because the bypass pipe 7 is constructed under optimum conditions between the first vacuum pump 1 and the second vacuum pump 2 which are integrally connected together into a pump unit according to the present invention.
  • the second vacuum pump 2 is illustrated and described as a screw-type dry pump.
  • the second vacuum pump 2 may comprise a roots dry pump, a diaphragm pump, or a scroll pump.
  • the second vacuum pump 2 comprises a diaphragm pump, then because the diaphragm pump is a pump having an evacuation principle for evacuating a gas by moving a diaphragm up and down to cause volumetric changes, the vertically moving direction (vibrating direction) of the diaphragm and the axial direction of the first vacuum pump should preferably be parallel to each other for the purpose of reducing overall vibrations of the vacuum evacuation apparatus.
  • the evacuation rate of a pump is controlled by adjusting the opening area of the suction side with a control valve or the like.
  • the pressure in the vacuum container to be evacuated is controlled by controlling at least one of the rotational speed of the first vacuum pump 1 and the rotational speed of the second vacuum pump 2 , rather than by adjusting the opening (opening area) of a valve disposed between the vacuum container and the pump.
  • the evacuation rate of each of the vacuum pumps 1 , 2 is adjusted to adjust the overall evacuation rate of the pump system as the vacuum evacuation apparatus.
  • the pressure in the vacuum container can be controlled by the single pump system without the need for a control valve other than the vacuum pumps.
  • FIG. 16 is a set of graphs showing comparison results in which the rotational speeds of first and second vacuum pumps were changed to adjust the pressure in a vacuum container in a pump rotational speed control process which was performed on a vacuum evacuation apparatus according to the present invention and a vacuum evacuation apparatus according to the related art, in the case of the first vacuum pump comprising a turbomolecular pump and the second vacuum pump comprising a dry pump.
  • the piping interconnecting the first vacuum pump (turbomolecular pump) and the second vacuum pump (dry pump) is very short. After pressure adjustment in the vacuum container is started, the rotational speed of the first vacuum pump is lowered, and when the pressure in the vacuum container reaches a certain level (start point of deceleration of the second pump), the second vacuum pump starts to reduce the rotational speed thereof. Since the piping interconnecting the first vacuum pump and the second vacuum pump is short, the pressure in the vacuum container quickly changes in response to the reduction in the rotational speed of the second vacuum pump.
  • the pressure in the vacuum container can reach a target pressure, i.e., the adjustment of the pressure in the vacuum container can be completed, in the shortest period of time.
  • the vacuum evacuation apparatus since the piping interconnecting the first vacuum pump and the second vacuum pumps is longer, the pressure in the vacuum container changes with a delay in response to the reduction in the rotational speed of the second vacuum pump, with the result that it consumes a certain period of time for the pressure in the vacuum container to reach a target pressure.
  • the second vacuum pump 2 should desirably be mounted on the first vacuum pump 1 . Consequently, it is desirable for the second vacuum pump 2 to have outer dimensions smaller than those of the first vacuum pump 1 .
  • the dimensions described below do not include those of electric components such as drivers, a controller, air-cooling fans, etc., but include only pump evacuation sections and actuators (motors).
  • the second vacuum pump according to the present invention comprises a dual-shaft positive displacement pump (screw rotors) and a magnetic coupling motor
  • the ultimate performance that can be achieved by the second vacuum pump is 400 Pa or lower.
  • the volume of the second vacuum pump can be smaller than the volume of the first vacuum pump, and thus there is no limitation on the mounting posture when the second vacuum pump is mounted on the first vacuum pump.
  • turbomolecular pump and a dual-shaft positive displacement pump are used respectively as the first vacuum pump and the second vacuum pump, it is possible to integrally connect a plurality of second vacuum pumps to the first vacuum pump which has an evacuation capacity that is several times greater than each of the second vacuum pumps.
  • FIG. 17 is a schematic view showing a vacuum evacuation apparatus according to an embodiment of the present invention, which includes a single first vacuum pump 1 and a plurality of second vacuum pumps 2 integrally connected to the first vacuum pump 1 .
  • the two second vacuum pumps 2 are integrally connected to the single first vacuum pump 1 .
  • the outlet port of the first vacuum pump 1 is connected to the inlet ports of the second vacuum pumps 2 by respective individual evacuation passage components 3 . Since the plural second vacuum pumps 2 are integrally connected to the single first vacuum pump 1 , it is possible to construct a roughing pump system having an evacuation capacity which matches the evacuation capacity of the first vacuum pump 1 .
  • the second vacuum pumps 2 have their overall evacuation capacity doubled.
  • the two parallel second vacuum pumps 2 can control the pressure in the vacuum container 5 more finely and quickly than a single second vacuum pump 2 .
  • the vacuum evacuation apparatus includes the two second vacuum pumps 2 , even if one of the second vacuum pumps 2 fails to operate, the other second vacuum pump 2 operates to keep the pressure in the outlet port of the first vacuum pump 1 below an allowable pressure level. Therefore, a situation where the first vacuum pump 1 shuts down to cause a quick pressure buildup in the vacuum container 5 can be avoided.
  • FIG. 19 is a schematic view showing a vacuum evacuation apparatus according to an embodiment of the present invention, which includes a plurality of first vacuum pumps 1 and a single second vacuum pump 2 which are integrally connected by evacuation passages.
  • a vacuum evacuation apparatus which includes a plurality of first vacuum pumps 1 and a single second vacuum pump 2 which are integrally connected by evacuation passages.
  • two parallel first vacuum pumps 1 and a single second vacuum pump 2 are integrally connected together into an integral pump unit that is mounted on a lower surface of the vacuum container 5 .
  • the outlet ports of the two first vacuum pumps 1 and the inlet port of the second vacuum pump 2 are interconnected by an evacuation passage component 3 .
  • the plural first vacuum pumps 1 and a single second vacuum pump 2 are integrally connected together into an integral pump unit, and hence each of the first vacuum pumps 1 is reduced in size.
  • FIG. 20 is a block diagram of a control circuit for controlling a vacuum evacuation apparatus including two first vacuum pumps 1 and a single second vacuum pump 2 which are integrally connected into an integral pump unit.
  • the control circuit includes a motor for one of the two first vacuum pumps 1 , i.e., TMP (turbomolecular pump) 1 , a motor for the other first vacuum pump 1 , i.e., TMP 2 , an inverter (INV) for the TMP 1 , an inverter (INV) for the TMP 2 , a motor for the second vacuum pump 1 , i.e., a DRY (dry) pump, and an inverter (INV) for the DRY pump.
  • TMP turbomolecular pump
  • the control circuit also includes a single controller (CPU) for integrally controlling the three inverters, i.e., the INV for the TMP 1 , the INV for the TMP 2 , and the INV for the DRY pump.
  • the CPU is capable of optimally controlling the pressure in the vacuum container by controlling the rotational speeds of the motors of the first and second vacuum pumps 1 , 2 at desired rotational speed control rates with the inverters without the need for pressure detectors in the evacuation pipes connected to the first and second vacuum pumps 1 , 2 .
  • the control circuit shown in FIG. 20 also includes a power factor controller (PFC) and a DC/DC converter (DC/DC).
  • FIG. 21 is a graph showing how the rotational speeds of a single first vacuum pump and two second vacuum pumps were changed to adjust the pressure in a vacuum container in a pump rotational speed control process which was performed on a vacuum evacuation apparatus according to the present invention, in the case of the first vacuum pump comprising a turbomolecular pump and the two second vacuum pumps comprising a dry pump.
  • the pressure in the vacuum container changes quickly in response to the reduction in the rotational speeds of the second vacuum pumps, and thus the pressure in the vacuum container can reach a target pressure (pressure adjustment completing point), in the shortest period of time.
  • the two second vacuum pumps start and stop reducing their rotational speeds at different times, the pressure in the vacuum container can be adjusted finely.
  • the first vacuum pump 1 comprises a turbomolecular pump having a pump casing 109 , and rotor blades 111 and stator blades 114 that are alternately mounted on a rotational shaft 113 and arranged successively from a central inlet port defined in the pump casing 109 toward left and right opposite ends of the rotational shaft 113 .
  • the multistage rotor blades 111 are integrally formed on the rotational shaft 113 , and the multistage stator blades 114 are fixed to the pump casing 109 .
  • the axes of the screw rotors of the second vacuum pump 2 are perpendicular to the axis of the rotational shaft 113 of the first vacuum pump 1 , and extend parallel to each other and are spaced by a common distance from the lower surface of the first vacuum pump 1 .
  • FIG. 24 shows a vacuum evacuation apparatus in which the fastening component 62 and the vibro-isolating bushings 63 shown in FIGS. 9 and 10 are disposed between the first vacuum pump 1 and the second vacuum pump 2 shown in FIG. 22 .
  • FIG. 25 shows a vacuum evacuation apparatus in which the fastening component 62 and the vibro-isolating bushings 63 shown in FIGS. 9 and 10 are disposed between the first vacuum pump 1 and the second vacuum pump 2 shown in FIG. 23 .
  • the first vacuum pump 1 and the second vacuum pump 2 are fastened to each other using a vibro-isolating mechanism including the vibro-isolating bushings 63 , the level of vibrations that are transmitted from the second vacuum pump 2 to the first vacuum pump 1 can be lowered.

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  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
US13/849,719 2012-03-30 2013-03-25 Vacuum evacuation apparatus Abandoned US20130259712A1 (en)

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JP2012080559A JP6009193B2 (ja) 2012-03-30 2012-03-30 真空排気装置
JP2012-080559 2012-03-30

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CN107709773A (zh) * 2015-07-23 2018-02-16 埃地沃兹日本有限公司 排气系统
US10232073B2 (en) * 2014-06-27 2019-03-19 Cmtech Co., Ltd. Vacuum exhaust system of sterilizer
WO2020070466A1 (en) * 2018-10-05 2020-04-09 Edwards Limited Portable vacuum pump assembly and mass spectrometer
CN112648202A (zh) * 2017-03-27 2021-04-13 株式会社岛津制作所 真空泵及泵一体型的电源装置
EP3748166A4 (en) * 2018-02-02 2021-11-03 Zhongshan Tianyuan Vacuum Equipment Technology Co., Ltd. ROOTS SEC AND MULTI-STAGE DEPRESSOR
CN113847244A (zh) * 2021-10-14 2021-12-28 四川莱斯特真空科技有限公司 一体式涡轮螺杆组合泵
US11396875B2 (en) * 2018-01-09 2022-07-26 Pfeiffer Vacuum Dry vacuum pump and method for controlling a synchronous motor of a vacuum pump

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EP3067567A1 (de) * 2015-03-11 2016-09-14 Pfeiffer Vacuum GmbH Vakuumpumpe
FR3042325B1 (fr) * 2015-10-13 2017-11-17 Ifp Energies Now Dispositif d'isolation thermique entre une turbine dont la roue est entrainee en rotation par un fluide chaud et une generatrice electrique avec un rotor accouple a cette roue, notamment pour une turbogeneratrice.
EP3267040B1 (de) * 2016-07-04 2023-12-20 Pfeiffer Vacuum Gmbh Turbomolekularpumpe
GB201715151D0 (en) * 2017-09-20 2017-11-01 Edwards Ltd A drag pump and a set of vacuum pumps including a drag pump
JP2021161917A (ja) * 2020-03-31 2021-10-11 エドワーズ株式会社 真空ポンプおよび真空ポンプの配管構造部
KR102479328B1 (ko) * 2020-12-11 2022-12-19 주식회사 듀얼드론텍 추진력 형성장치 및 이를 이용한 무인비행체

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US20060225421A1 (en) * 2004-12-22 2006-10-12 Denso Corporation Device for utilizing waste heat from heat engine
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US20160258448A1 (en) * 2013-09-26 2016-09-08 Inficon Gmbh Evacuation of a Film Chamber
US10844877B2 (en) * 2013-09-26 2020-11-24 Inficon Gmbh Evacuation of a film chamber
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CN107709773A (zh) * 2015-07-23 2018-02-16 埃地沃兹日本有限公司 排气系统
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US11396875B2 (en) * 2018-01-09 2022-07-26 Pfeiffer Vacuum Dry vacuum pump and method for controlling a synchronous motor of a vacuum pump
EP3748166A4 (en) * 2018-02-02 2021-11-03 Zhongshan Tianyuan Vacuum Equipment Technology Co., Ltd. ROOTS SEC AND MULTI-STAGE DEPRESSOR
WO2020070466A1 (en) * 2018-10-05 2020-04-09 Edwards Limited Portable vacuum pump assembly and mass spectrometer
CN113847244A (zh) * 2021-10-14 2021-12-28 四川莱斯特真空科技有限公司 一体式涡轮螺杆组合泵

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EP2644893A2 (en) 2013-10-02
JP6009193B2 (ja) 2016-10-19
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JP6333908B2 (ja) 2018-05-30
EP2644893A3 (en) 2017-08-23
JP2013209928A (ja) 2013-10-10

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