JP2005155403A - Vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump suitable for obtaining high vacuum by preventing temperature rise of a rotor and a rotor blade. <P>SOLUTION: Nickel coating 15 is applied on an outer shape surface of an aluminum alloy rotor 4 or an outer shape surface of a rotor blade 19. Coating of carbon based material such as DLC coating 16 is applied on nickel coating 15 film. A bypass structure increasing heat conductivity of a fastening part 8 and collecting heat of the rotor 4 to a rotor shaft 5 side by .heat conduction via the fastening part 8 is adopted in the fastening part of the rotor 4 and the rotor shaft 5. An inner circumference surface of a stator column facing an outer circumference surface of the rotor shaft 5 is covered by film 14-1 composed of material of higher radiation rate than that. High heat conduction rate member 14-2 composed of higher heat conduction rate material 14-2 than an inner circumference surface of a stator column is exposed at the inner circumference surface of the stator column. The exposed surface of the higher heat conduction rate material 14-2 is covered by the film 14-1 composed of material of higher radiation than that. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vacuum pump used in a semiconductor manufacturing apparatus, a liquid crystal display panel manufacturing apparatus, or the like.

  FIG. 5 shows an example of a conventional vacuum pump. The vacuum pump in the figure is a type in which a turbo molecular pump Pt and a screw pump Ps are combined. In this type of vacuum pump, when the rotor 4 rotates integrally with the rotor shaft 5 supported by the radial magnetic bearing 17 and the axial magnetic bearing 18, an intake port is formed between the outer peripheral surface of the rotor 4 and the surface facing the rotor 4. The operation of compressing while transporting gas molecules from the 2 side toward the exhaust port 3 side is performed.

  That is, on the upstream side near the intake port 2 between the outer peripheral surface of the rotor 4 and the surface facing the rotor 4, there are a rotor blade 19 that rotates integrally with the rotor 4 and a stator blade 20 that is fixed in place. The portion of the blade structure composed of the rotor blade 19 and the stator blade 20 constitutes a turbo molecular pump Pt stage.

  In such a turbo molecular pump Pt stage, the gas molecules on the intake port 2 side are compressed while being transferred downward in FIG. 5 by the interaction between the rotating rotor blade 19 and the fixed stator blade 20.

  There is a fixed screw pump stator 22 having a screw groove 23 on the side facing the outer peripheral surface of the rotor 4 on the downstream side near the exhaust port 3 between the outer peripheral surface of the rotor 4 and the surface facing this. The screw pump Ps stage is constituted by the screw groove 23 of the screw pump stator 22 and the outer peripheral surface of the rotor 4.

  In such a screw pump Ps stage, gas molecules are compressed while being transferred downward in FIG. 5 by the interaction between the outer peripheral surface of the rotating rotor 4 and the fixed screw groove 23.

  In the vacuum pump having the above-described structure, gas molecules are compressed between the outer peripheral surface of the rotor 4 and the surface facing the rotor 4, so that compression heat is generated between them, and the rotor 4 and the rotor blades 19 are caused by this compression heat. Heated.

  In this case, the heat radiation from the rotating rotor 4 and the rotor blade 19 to the fixed portion side such as the screw pump stator 22 includes (1) the heat conduction of the compressed and transported gas and (2) the outer surface of the rotor 4 and the rotor blade 19. This is done by radiant heat transfer from the outer surface.

  Here, since the vacuum pump having the above structure employs a structure in which the rotor 4 and the rotor shaft 5 are supported by the non-contact magnetic bearings 17 and 18, the heat of the rotor 4 is dissipated by heat conduction through the bearings. There is nothing. Further, when the heat conduction of the gas compressed and transferred in the vacuum pump, such as an inert gas such as Ar, Xe, or Kr, is low, heat radiation due to the action (1) can hardly be expected.

  Therefore, the heat radiation by the action (2), that is, the radiant heat transfer from the outer surface of the rotor 4 and the outer surface of the rotor blade 19 is the only heat radiating means for removing the heat on the rotor 4 side.

  However, since the rotating rotor 4 and the rotor blade 19 are made of a lightweight metal, specifically, an aluminum alloy, the radiation rate of the outer surface of the rotor 4 and the outer surface of the rotor blade 19 is small.

As means for solving the problem of emissivity in the aluminum alloy rotor 4 as described above, there is (i) a method of providing a DLC (diamond-like carbon) coating film on the surface of the aluminum alloy. (For example, refer to Patent Document 1.)
The DLC coating film has high emissivity, excellent corrosion resistance to fluorine and hydrochloric acid, has high hardness, and is not easily damaged. Means for improving the emissivity of the outer surface of the rotor 4 and the outer surface of the rotor blade 19 As a DLC coating film is suitable.

  However, aluminum and carbon deteriorate each other by forming a compound called aluminum carbide having a low mechanical strength. Therefore, in the vacuum pump of FIG. 5, when the DLC coating film is provided on the outer surface of the rotor 4 made of aluminum alloy or the outer surface of the rotor blade 19, the outer surface of the rotor 4 or the outer surface of the rotor blade 19 and the DLC coating film Aluminum carbide with low mechanical strength is formed between them, peeling or dropping of the DLC coating film occurs, and contamination such as falling pieces of the DLC coating film can occur in the vacuum pump. Therefore, the DLC coating film cannot be used as a heat dissipation means for the rotor 4 or the rotor blade 19 as it is. Note that carbon-based materials or diamond-based materials other than DLC are the same as DLC.

  In addition, as a means for solving the problem of emissivity in the aluminum alloy rotor 4 and the rotor blade 19 as described above, there is another method of providing a ceramic dispersed metal plating film on the outer surface of the rotor 4 and the outer surface of the rotor blade 19. is there. (For example, refer to Patent Document 2).

  However, in the vacuum pump shown in FIG. 5, when the structure in which the ceramic dispersed metal plating film is provided on the outer surface of the rotor 4 and the outer surface of the rotor blade 19, there is a problem of water absorption, alteration, and scattering of ceramic particles. Since contamination called particles is generated in the vacuum pump, the ceramic-dispersed metal plating film cannot be employed as a heat dissipation means for the rotor 4 or the rotor blade 19.

  As described above, the DLC coating film or the ceramic-dispersed metal plating film cannot be employed as a heat dissipating means for the rotor 4 or the rotor blades 19 and cannot prevent the rotor 4 and the rotor blades 19 from being heated.

  In the vacuum pump of FIG. 5, as described above, the non-contact magnetic bearings 17 and 18 are employed as bearings for supporting the rotor shaft 5. In this case, the rotor shaft is generated by the magnetic field generated by the magnetic bearings 17 and 18. An eddy current is generated inside the rotor 5, and the rotor shaft 5 itself may generate heat due to the rotational resistance of the eddy current.

  As a means for radiating the heat of the rotor shaft 5, conventionally, a coating made of a material having a high thermal emissivity is provided on the outer peripheral surface of the rotor shaft 5 (shaft). (For example, refer to Patent Document 3).

  However, since the coating is provided on the outer peripheral surface of the rotor shaft 5 as means for increasing the radiation rate of heat from the rotor shaft 5 to the device housing side that accommodates it, the effect of increasing the heat radiation efficiency from the rotor shaft 5 is achieved. However, it is not possible to expect the effect of transmitting the radiant heat from the rotor shaft to the stator column 10 installed on the outer periphery of the rotor shaft and efficiently radiating heat to the outside by heat conduction.

JP 2002-47556 A

JP 2000-205181 A

JP-A-10-122178

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vacuum pump suitable for obtaining a high vacuum by preventing the temperature of the rotor and rotor blades from rising. is there.

  To achieve the above object, the present invention provides a cylindrical rotor housed in an exterior case having an intake port and an exhaust port, and a rotor shaft disposed inside the rotor and fastened to an axis of the rotor. And a bearing that rotatably supports the rotor shaft about its axis, a rotational drive motor that rotates the rotor shaft, and a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft. And provided between a stator column that houses pump interior parts such as the bearing and the rotary drive motor, and an outer peripheral surface of the rotor and a surface facing the stator column, and the intake port is rotated by rotation of the rotor. Transporting and compressing means for compressing gas molecules while transporting gas molecules from the side toward the exhaust port side, the rotor has rotor blades on the outer peripheral surface thereof, and the rotor and rotor blades are made of an aluminum alloy base. Between the carbon-based coating thereon, the aluminum alloy and carbon material is characterized in that consisting of those having a middle layer of different materials.

  In the present invention, the formation of a compound having no mechanical strength such as aluminum carbide is suppressed by the barrier effect of the intermediate layer interposed between the base material of the aluminum alloy and the carbon-based film. Even a carbon-based material can be attached to the rotor outer surface and rotor blade outer surface made of aluminum alloy without causing peeling or dropping, and the occurrence of contamination in the vacuum pump is prevented. Therefore, it becomes possible to employ carbon-based materials and diamond-based materials as heat dissipation means for aluminum alloy rotors and rotor blades, and by adopting them, heat is radiated from the rotor and rotor blades by radiant heat conduction from the rotor outer surfaces and rotor blade outer surfaces. The amount of heat generated increases.

  The intermediate layer may be formed of a layer made of a metal material such as nickel. The intermediate layer may be selected from any one of an aluminum oxide layer formed by oxidizing the aluminum alloy base material, a ceramic layer, and a resin material layer.

  As the metal material, in addition to nickel, for example, silicon, copper, chromium, a chromium compound by chromate treatment, zinc, or the like can be applied.

  As the ceramic, for example, aluminum oxide, silicon nitride, silicon oxide, methane nitride, or the like can be applied.

  As the resin material, for example, a fluorine resin, an epoxy resin, or a silicone resin can be applied.

  The above examples of metal materials, ceramics, and resin materials all have a barrier effect without reacting with both aluminum and carbon materials, and both aluminum and carbon materials become aluminum carbide and both deteriorate. It is to prevent that.

  In the present invention, “an intermediate layer made of a material different from aluminum alloy or carbon-based material is provided between an aluminum alloy base material and a carbon-based coating thereon” is shown in FIG. 2 or FIG. 3, for example. Thus, a nickel coating (15) coating is provided between the outer surface of the aluminum alloy rotor (4) or the rotor blade (19) outer surface and the DLC coating (16) coating thereon. Here, the “rotor outer surface” is opposed to the rotor outer peripheral surface on which the rotor blades (19) are provided or the stator column (10), such as the cylindrical rotor (4) shown in FIG. Including the inner circumferential surface of the rotor. The “rotor blade outer surface” includes, for example, the rotor blade surface seen from the intake port 2 side and the back surface thereof, like the rotor blade (19) of the vacuum pump shown in FIG.

  The carbon-based film includes a film made of DLC or other carbon-based material.

  In the present invention, it is possible to employ a configuration in which the inner peripheral surface of the stator column facing the outer peripheral surface of the rotor shaft is covered with a coating made of a material having a higher emissivity. According to this configuration, the amount of heat radiation due to radiant heat transfer from the outer circumferential surface of the rotor shaft increases, and the heat amount of the rotor and rotor blades transmitted to the rotor shaft side by heat transfer is smoothly radiated by radiant heat transfer from the rotor shaft outer circumferential surface. Therefore, the amount of heat from the rotor and rotor blades does not accumulate on the rotor shaft, and the amount of heat from the rotor and rotor blades can be efficiently removed.

  In the present invention, a high thermal conductivity member made of a material having a higher thermal conductivity is exposed on the inner peripheral surface of the stator column facing the outer peripheral surface of the rotor shaft, and the high thermal conductivity is exposed. You may employ | adopt the structure formed by the exposed surface of a member being covered with the film which consists of a substance with a higher emissivity than it. According to this configuration, the amount of heat transferred from the rotor shaft to the stator column side is further efficiently radiated through the high thermal conductivity member.

  The present invention relates to a cylindrical rotor housed in an outer case having an intake port and an exhaust port, a rotor shaft disposed inside the rotor and fastened to an axis of the rotor, and the rotor shaft as a shaft thereof. A bearing that is rotatably supported around the center, a rotational drive motor that rotates the rotor shaft, a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft, and the bearing and the A stator column that houses pump interior components such as a rotary drive motor, and an outer peripheral surface of the rotor and a surface facing the stator column, and is rotated from the intake port side to the exhaust port side by the rotation of the rotor. A transfer compression means for compressing the gas molecules while transferring the gas molecules, and a heat conduction bypass portion from the rotor to the rotor shaft side. The bypass portion is provided inside the upper end of the rotor. The rotor shaft small diameter part provided on the shaft upper end surface of the rotor shaft is inserted into the through hole of the cutting step, and in this state, the shaft is fitted by shrink fitting such that the through hole strongly tightens the rotor shaft small diameter part. It is characterized by comprising a structure.

  In the present invention, the shaft fitting structure portion by the shrink fit of the rotor and the rotor shaft as described above increases the heat conduction amount and becomes a heat conduction bypass, through which the heat amount from the rotor and rotor blades is transferred to the rotor shaft side. It is transmitted to and is dissipated.

  The present invention relates to a cylindrical rotor housed in an outer case having an intake port and an exhaust port, a rotor shaft disposed inside the rotor and fastened to an axis of the rotor, and the rotor shaft as a shaft thereof. A bearing that is rotatably supported around the center, a rotational drive motor that rotates the rotor shaft, a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft, and the bearing and the A stator column that houses pump interior components such as a rotary drive motor, and an outer peripheral surface of the rotor and a surface facing the stator column, and is rotated from the intake port side to the exhaust port side by the rotation of the rotor. A transfer compression means for compressing the gas molecules while transferring the gas molecules, and a heat conduction bypass portion from the rotor to the rotor shaft side. The bypass portion is provided inside the upper end of the rotor. A boss portion is integrally formed as a part of the rotor on the lower surface of the cutting step. An insertion hole for the boss portion is formed on the upper end surface of the rotor shaft, and the rotor is inserted into the insertion hole on the upper end surface of the rotor shaft. The boss portion which is a part of the boss portion is inserted.

  In the present invention, the portion of the structure formed by inserting the boss portion into the insertion hole as described above increases the amount of heat conduction and serves as a heat conduction bypass. Through this bypass, the amount of heat from the rotor and rotor blades moves to the rotor shaft side. It is transmitted and dissipated.

  The bearing can be a magnetic bearing.

  According to the present invention, as described above, it becomes possible to employ a carbon-based material or a diamond-based material as a heat radiating means for an aluminum alloy rotor or rotor blade, and by adopting it, radiation heat transfer from the rotor outer surface and the rotor blade outer surface can be achieved. The amount of heat of the removed rotor and rotor blades increases, and a vacuum pump suitable for obtaining a high vacuum can be obtained.

  The heat dissipation effect of the rotor and rotor blade as described above is particularly effective when exhausting a gas having a low thermal conductivity. In Xe, it is estimated that the temperature of the rotor blades is reduced by 50 ° C. In this case, the allowable flow rate of the exhausted gas becomes 10 times.

  According to the present invention, the adoption of the bypass portion having the above structure increases the heat conduction from the rotor to the rotor shaft side, increases the amount of heat radiated from the rotor and rotor blades, and is suitable for obtaining a high vacuum. A vacuum pump is obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  The vacuum pump shown in FIG. 1 is used as a part of a vacuum apparatus in a semiconductor manufacturing apparatus or a liquid crystal display panel manufacturing apparatus, and makes the pressure in the vacuum chamber a predetermined degree of vacuum.

  Moreover, the vacuum pump of the figure is a composite pump having a part functioning as the turbo molecular pump Pt and a part functioning as the screw pump Ps in the outer case 1.

  The outer case 1 has a bottomed cylindrical case structure in which a cylindrical pump case 1-1 and a cylindrical pump base 1-2 are integrally connected with bolts in the cylinder axial direction.

  The upper end portion side of the pump case 1-1 opens as an intake port 2, and an exhaust port 3 is opened on the side surface of the lower end portion of the pump base 1-2.

  A cylindrical rotor 4 is accommodated in the outer case 1. The rotor 4 is arranged such that its upper end side faces the intake port 2 and its lower end side faces the pump base 1-2. A rotor shaft 5 is provided inside the rotor 4. The rotor shaft 5 is disposed at the axial center of the rotor 4 and is fastened integrally with the rotor 4 on the shaft upper end 5a side.

  The fastening structure of the rotor shaft 5 and the rotor 4 will be specifically described. In the present embodiment, the rotor shaft 5 and the rotor 4 are fastened by shrink fitting.

  That is, a shaft portion 5-1 having a smaller diameter (hereinafter referred to as a rotor shaft small diameter portion) is provided on the shaft upper end surface of the rotor shaft 5. On the other hand, a partition step 6 is provided on the inner side of the upper end 4 a of the rotor 4, and a through hole 7 penetrating the front and back surfaces of the partition step 6 is formed at the center of the partition step 6. The through hole 7 has a diameter smaller than that of the rotor shaft small diameter portion 5-1 in the rated operating temperature range of the vacuum pump. However, when the periphery of the through hole 7 is heated to a temperature higher than the temperature range, the through hole 7 expands. The diameter becomes larger than that of the rotor shaft small diameter portion 5-1. At this time, after inserting the rotor shaft small-diameter portion 5-1 into the through-hole 7, if the periphery of the through-hole 7 is cooled, the shaft fits by shrink fitting such that the through-hole 7 strongly tightens the rotor shaft small-diameter portion 5-1. Thus, the rotor 4 and the rotor shaft 5 are fastened and fixed integrally.

  When the rotor 4 and the rotor shaft 5 are fastened as described above, the contact between the rotor 4 and the rotor shaft 5 at the fastening portion 8 becomes dense, thereby forming a bypass portion for heat conduction from the rotor 4 to the rotor shaft 5 side. Thus, heat conduction from the rotor 4 to the rotor shaft 5 side is improved.

  That is, in this embodiment, the rotor 4 and the rotor shaft 5 are fastened by shrink fitting so that the heat of the rotor 4 is efficiently transferred to the rotor shaft 5 side through the fastening portion 8 by heat conduction. It is.

  The partition stage 6 has a plurality of bolt insertion holes (not shown) around the through hole 7. A fastening bolt 9 is inserted into the bolt insertion hole from the upper surface side of the partition stage 6, and a bolt front end portion of the fastening bolt 9 is fastened to a screw hole (not shown) on the upper end surface of the rotor shaft 5. In this way, the rotor shaft 5 and the rotor 4 are fastened and fixed by the fastening bolt 9.

  At this time, the surface of the flange portion 27 formed on the outer periphery of the upper end of the rotor shaft 5 is brought into close contact with the back surface of the partition step 6 by the fastening force of the fastening bolt 9. The reason for adopting such a close-contact structure is to increase the contact area between the rotor shaft 5 and the rotor 4 as much as possible to enhance the heat conduction from the rotor 4 to the rotor shaft 5 side.

  A stator column 10 is installed in a space between the inner peripheral surface of the rotor 4 and the outer peripheral surface of the rotor shaft 5. The stator column 10 is located in the center of the pump case 1-1 and is formed in a cylindrical shape surrounding the outer peripheral surface of the rotor shaft 5. The stator column 10 is erected on the pump base 1-2 by screwing and fixing the lower end of the cylinder onto the pump base 1-2.

  Inside the stator column 10, various pump interior parts such as a bearing 11 that supports the rotor shaft 5 and a rotary drive motor 12 that rotates the rotor shaft 5 about its axis are accommodated.

  Magnetic bearings are employed for the bearings 11 that support the rotor shaft 5. The magnetic bearing is composed of a radial magnetic bearing 17 and an axial magnetic bearing 18.

  Two radial magnetic bearings 17 are arranged in the vertical direction of the rotary drive motor 12 arranged in the vicinity of the center of the stator column 10, and a total of two sets of the rotary body composed of the rotor shaft 5 and the rotor 4 are arranged on the rotary magnetic motor 17. Support in the radial direction.

  That is, the two sets of radial magnetic bearings 17 include a radial electromagnet target 17-1 attached to the outer peripheral surface of the rotor shaft 5 and a plurality of radial electromagnets 17 embedded in the inner surface of the stator column 10 facing the radial electromagnet target 17-1. -2 and radial direction displacement sensor 17-3.

  And the radial electromagnet target 17-1 consists of a laminated steel plate which laminated | stacked the steel plate of the high magnetic permeability material, and the radial electromagnet 17-2 attracts | sucks the rotor shaft 5 with the magnetic force to the radial direction via the radial electromagnet target 17-1. . The radial displacement sensor 17-3 detects the radial displacement of the rotor shaft.

  The excitation current of the radial electromagnet 17-2 is controlled on the basis of the detection value (radial displacement of the rotor shaft) of the radial direction displacement sensor 17-3, whereby the rotating body composed of the rotor shaft 5 and the rotor 4 is The whole is levitated and supported at a predetermined position in the radial direction.

  One set of axial magnetic bearings 18 is arranged on the lower end side of the rotor shaft 5 and supports the entire rotating body including the rotor shaft 5 and the rotor 4 in the axial direction.

  That is, the axial magnetic bearing 18 includes a disk-shaped armature disk 18-1 attached to the outer periphery of the lower end portion of the rotor shaft 5 and an axial electromagnet 18 disposed at the upper and lower positions opposed to each other with the armature disk 18-1. -2 and an axial direction displacement sensor 18-3 installed at a position slightly away from the lower end surface of the rotor shaft 5.

  The armature disk 18-1 is made of a material having a high magnetic permeability, and the upper and lower axial electromagnets 18-2 attract the armature disk 18-1 from the vertical direction with a magnetic force. The axial direction displacement sensor 18-3 detects the axial displacement of the rotor shaft 5.

  The exciting current of the upper and lower axial electromagnets 18-2 is controlled based on the detected value (axial displacement of the rotor shaft) by the axial direction displacement sensor 18-3, whereby the rotating body composed of the rotor shaft 5 and the rotor 4 is The whole is levitated and supported at a predetermined position in the axial direction.

  In the rotation drive motor 12, the motor stator 12-1 is installed inside the stator column 10, and the motor rotor 12-2 is installed integrally with the rotor shaft 5.

  Various electric parts such as a radial electromagnet 17-2, a radial direction displacement sensor 17-3, and a rotary drive motor 12 housed inside the stator column 10 are molded by space or epoxy resin.

  The substantially upper half of the rotor 4 functions as a turbo molecular pump Pt. Hereinafter, the part which functions as this turbo-molecular pump Pt is demonstrated.

  In the space between the upper outer peripheral surface of the rotor 4 and the surface facing this, specifically, the inner wall surface of the pump case 1-1, the rotor blades 19 and the stator blades 20 constituting the turbo molecular pump Pt are provided. Are arranged alternately and in multiple stages along the central axis of the rotor shaft 5 or the pump case 1-1 (hereinafter referred to as the pump axis).

  The rotor blade 19 is composed of a blade inclined at a predetermined angle, and is integrally formed on the upper outer peripheral surface of the rotor 4. Further, a plurality of rotor blades 19 are provided radially in the circumferential direction of the rotor 4 with the pump axis as the center.

  The stator blade 20 is composed of blades inclined in the opposite direction to the rotor blade 19 and is sandwiched and fixed in place by blade fixing spacers 21 stacked on the inner wall surface side of the pump case 1-1. Yes. Further, a plurality of stator blades 20 are also provided radially in the circumferential direction of the pump case 1-1 around the pump axis.

  In the vacuum pump of FIG. 1, the rotor blade 19 and the stator blade 20 are provided in five stages. Further, in order to exhibit the desired exhaust performance, the clearance between the rotor blade 19 and the stator blade 20 gradually becomes narrower from the uppermost stage to the lowermost stage of the rotor blade 19 and the stator blade 20. The lengths (blade lengths) of the rotor blades 19 and the stator blades 20 are also shortened.

  The substantially lower half of the rotor 4 functions as a screw pump Ps. Hereinafter, the part functioning as the screw pump Ps will be described.

  A screw pump stator 22 constituting a screw pump Ps is installed between the outer peripheral surface of the lower side of the rotor 4 and the surface facing this, specifically, the inner wall surface of the pump case 1-1. The screw pump stator 22 is formed in a cylindrical shape surrounding the lower outer peripheral surface of the rotor 4 and is installed on the pump base 1-2.

  In the vacuum pump of this embodiment, a screw groove 23 is formed on the cylindrical inner surface of the screw pump stator 22, and the lower outer peripheral surface of the rotor 4 facing the screw groove 23 is formed on a smooth cylindrical surface. Yes. Further, a minute clearance is provided between the screw pump stator 22 and the rotor 4.

  The thread groove 23 is spirally engraved from the upper end 22 a to the lower end 22 b of the screw pump stator 22. The upstream end 23a side of the screw groove 23 communicates with a minute gap between the lowermost rotor blade 19 (19-2) and the stator blade 20 (20-2), and the downstream end 23b side of the screw groove 23 is It is configured to communicate with the exhaust port 3 side. Further, in order to exhibit a desired exhaust performance, the thread groove 23 is formed so as to become shallower from the upstream end 23a toward the downstream end 23b.

  A cooling pipe 24 is installed below the pump base 1-2. The coolant flowing in the cooling pipe 24 cools the pump base 1-2 and the stator column 10 and the screw pump stator 22 installed directly on the pump base 1-2, and the temperature is controlled to a relatively low temperature state.

  Further, since the lowermost blade fixing spacer 21 for positioning and fixing the stator blade 20 is directly disposed on the screw pump stator 22, the blade fixing spacer 21 and the stator blade 20 are also cooled by heat conduction and relatively low in temperature. Temperature controlled to state.

  In the vacuum pump of FIG. 1, the rotor 4 and the rotor blade 19 are made of an aluminum alloy. As shown in FIGS. 2 and 3, nickel coating 15 is applied to the outer peripheral surface of the rotor 4 and the outer surface of the rotor blade 19 which are the outer surfaces of the aluminum alloy rotor 4, and the nickel coating 15 is further provided. A DLC (diamond-like carbon) coating 16 is applied as a carbon-based material on the coating 15.

  A nickel coating 15 film is interposed between the DLC coating 16 film and the outer peripheral surface of the rotor 4 made of aluminum alloy and the outer surface of the rotor blade 19. For this reason, the production | generation of the compound called aluminum carbide considered to be the cause of peeling and dropping of the DLC coating 16 is suppressed.

  Therefore, even the rotor 4 and the rotor blade 19 having an aluminum alloy as a base material can be provided with a DLC coating 16 film that adheres firmly, has high emissivity, and is particularly excellent in corrosion resistance to fluorine and hydrochloric acid, and also has hardness. It is possible to effectively use the characteristics of the DLC coating 16 that is high and hardly scratched.

  The inner peripheral surface of the stator column 10 facing the outer peripheral surface of the rotor shaft 5 is provided with a coating 14-1 made of a material having a higher emissivity. Specifically, the high thermal conductivity member 14-2 made of a material having high thermal conductivity is exposed on the inner peripheral surface of the stator column 10, and the exposed surface of the high thermal conductivity member 14-2 is exposed. It is assumed that the coating 14-1 is directly provided.

  About the installation structure of the high heat conductivity member 14-2, in this embodiment, the structure where the high heat conductivity member 14-2 is installed in the molding part 26 of electrical components, such as the radial electromagnet 17-2, is employ | adopted. .

  The high thermal conductivity member 14-2 is provided to transmit heat from the outer peripheral surface of the rotor shaft 5 to the inner peripheral surface of the stator column 10 to the stator column 10 for heat dissipation. In view of the role or function of the high thermal conductivity member 14-2, the high thermal conductivity member is made of, for example, aluminum, copper, iron, silicon, or the like.

  For the coating 14-1 on the inner peripheral surface of the stator column 10, an oxidation-treated coating, a black body coating film, or the like is employed. Moreover, if the site | part which provides the film 14-1 is aluminum, you may employ | adopt an alumite process film.

  Next, the operation of the vacuum pump of FIG. 1 configured as described above will be described.

  In the vacuum pump of FIG. 1, the rotor shaft 5 and the rotor 4 rotate integrally at a high speed when the rotary drive motor 12 is activated. Then, in the turbo molecular pump Pt stage, due to the interaction between the rotor blades 19 and the stator blades 20, the lowermost rotor blades 19 (19-2) and the stator blades 20 ( The operation of exhausting gas molecules toward the 20-2) side is performed.

  That is, in the vicinity of the inlet 2, the collision between the gas molecules is a free molecular state that is significantly less than the collision between the gas molecule and the inner wall of the gas exhaust flow path. Momentum is given by the collision with the rotor blade 19 (19-1) and the stator blade 20 (20-1), and the rotor blade 19 and the stator blade 20 are moved to the next rotor blade 19 and the stator blade 20 side. Are mixed. Among these, gas molecules moving to the rotor blade 19 and stator blade 20 side of the next stage are given momentum by collision with the rotor blade 19 and the stator blade 20, and further lower rotor blade 19 and stator blade 20. There is something that moves to the side.

  As described above, the gas molecules moving from the uppermost stage to the lower stage of the rotor blades 19 and the stator blades 20 are gas exhaust passages of the turbo molecular pump Pt stage, that is, the gap between the rotor blades 19 and the stator blades 20. Since the passage is gradually narrowed, it is shifted to the next screw pump Ps stage side while being gradually compressed into an intermediate flow state.

  In the screw pump Ps stage, the flow of gas molecules from the upstream end 23 a to the downstream end 23 b of the screw groove 23 is induced by the lower outer peripheral surface (moving wall) of the rotating rotor 4. The gas molecules in the intermediate flow pressure state on the rotor blades 19 (19-2) and the stator blades 20 (20-2) on the lowermost stage riding on the induced flow of gas molecules are transferred to the upstream end 23a of the screw groove 23. Is incident on.

  The gas molecules in the pressure state of the sucked intermediate flow are spirally formed by the gas exhaust passage of the screw pump Ps stage that gradually becomes shallower from upstream to downstream, that is, the lower outer peripheral surface of the rotor 4 and the screw groove 23. By being guided by the passage, it is shifted to the exhaust port side while being compressed into a viscous flow state having a high pressure.

  In short, the vacuum pump of FIG. 1 has a portion (specifically, a rotor blade 19) that functions as a turbo molecular pump Pt by the rotation of the rotor 4 in a space between the outer peripheral surface of the rotor 4 and the surface facing the rotor 4. And a portion that functions as a screw pump Ps (a portion that includes a screw pump stator 22 and a lower outer peripheral surface of the rotor 4 that faces the screw groove 23). By the transfer compression means called the turbo molecular pump Pt and the screw pump Ps, the gas molecules are compressed while being transferred from the intake port 2 side to the exhaust port 3 side.

  In the vacuum pump of FIG. 1, gas molecules are compressed in a turbo molecular pump Pt stage and a screw pump Ps stage. This compression is performed on the outer peripheral surface side of the rotor 4, specifically, a gap passage between the rotor blade 19 and the stator blade 20, or a spiral passage formed by the lower outer peripheral surface of the rotor 4 and the screw groove 23.

  For this reason, compression heat is generated on the outer peripheral surface side of the rotor 4, and the rotor 4 and the rotor blades 19 are directly heated by this compression heat. In addition, since there is no site | part which compresses in the inner peripheral surface side of the rotor 4, the rotor shaft 5 etc. which are located in the inner peripheral surface side of the rotor 4 are not directly heated by compression heat.

  A part of the heat of the rotor 4 and the rotor blades 19 is a low-temperature screw whose temperature is controlled by radiation from the outer peripheral surface of the rotor 4 and the outer surface of the rotor blade 19 to the inner peripheral surface side of the screw pump stator 22 and the stator blade 20 side. It is transmitted to the pump stator 22 and the stator blade 20 side.

  At this time, since the outermost surface of the outer peripheral surface of the rotor 4 and the outer surface of the rotor blade 19 is the DLC coating 16 coating, the amount of heat radiation from the outer peripheral surface of the rotor 4 and the outer surface of the rotor blade 19 is large. The amount of heat is efficiently dissipated. This is the first heat removal route or heat dissipation route for the rotor and rotor blades in this embodiment.

  A part of the heat of the rotor 4 and the rotor blades 19 is transmitted to the rotor shaft 5 side by heat conduction through the fastening portion 8 between the rotor 4 and the rotor shaft 5.

  At this time, since the rotor 4 and the rotor shaft 5 are fastened by shrink fitting, the heat conduction of the fastening portion 8 is good, and therefore the heat of the rotor 4 is efficiently transferred from the rotor 4 to the rotor shaft 5 side through the fastening portion 8. Is transmitted. This is the second heat removal route or heat release route for the rotor and rotor blades in this embodiment.

  The heat of the rotor 4 and the rotor blades 19 transmitted to the rotor shaft 5 side as described above is further controlled by the radiation from the outer peripheral surface of the rotor shaft 5 to the inner peripheral surface of the stator column 10, and the temperature of the low-temperature stator column 10 is controlled. It is transmitted to.

  At this time, since the outer peripheral surface of the rotor shaft 5 and the inner peripheral surface of the stator column 10 are covered with the coatings 13 and 14 having high emissivity, the amount of heat radiation from the outer peripheral surface of the rotor shaft 5 to the inner peripheral surface of the stator column 10 is In many cases, the heat quantity of the rotor shaft 5 is efficiently removed.

  1 employs a magnetic bearing as the bearing 11 that rotatably supports the rotor shaft 5, an eddy current is generated inside the rotor shaft 5 due to the magnetic field of the magnetic bearing. Although the heat generation of the rotor shaft 5 may also occur, the heat of the rotor shaft 5 generated through such a process is also generated from the outer peripheral surface of the rotor shaft 5 in the same manner as the heat collected from the rotor 4 side to the rotor shaft 5 side. The radiation to the inner peripheral surface of the column 10 is transmitted to the stator column 10 side and radiated.

  In the vacuum pump of the above embodiment, the rotor 4 and the rotor shaft 5 are fastened by shrink fitting to form a heat conduction bypass portion from the rotor to the rotor shaft side. For example, FIG. A structure like the vacuum pump shown can also be adopted.

  That is, in the vacuum pump of FIG. 4, a boss portion 4-1 is integrally formed as a part of the rotor 4 on the lower surface of the partition stage 6 provided inside the upper end portion 4a of the rotor 4, and the boss The insertion hole 25 of the part 4-1 is formed in the upper end surface of the rotor shaft 5, and the boss part 4-1 as a part of the rotor 4 is inserted into the insertion hole 25 of the upper end surface of the rotor shaft. Yes.

  In the case of this structure, the boss portion 4-1 on the rotor 4 side and the insertion hole 25 on the rotor shaft 5 side into which the boss portion 4-1 is inserted are fastened by shrink fitting, so that the fastening portion 8 between the rotor 4 and the rotor shaft 5 is secured. Is configured. Also in such a fastening structure, the rotor shaft 5 and the rotor 4 are fastened and fixed by the fastening bolt 9, and the flange portion 27 on the outer periphery of the upper end of the rotor shaft 5 is in close contact with the partition stage 6 by the fastening force. This is the same as the fastening structure of FIG. 1, and detailed description thereof is omitted.

  When the structure in which the boss 4-1 of the rotor 4 is inserted into the insertion hole 25 on the rotor shaft 5 side by shrink fitting as described above is adopted, the fastening portion 8 between the rotor 4 and the rotor shaft 5 is used. The contact area at increases. For this reason, the heat conduction from the rotor 4 to the rotor shaft 5 side via the fastening portion 8 allows the heat amount of the rotor 4 and the rotor blade 19 to be collected more efficiently on the rotor shaft 5 side. The heat dissipation efficiency is further improved.

  In the vacuum pump of the above embodiment, the example in which the nickel coating 15 is applied on the outer peripheral surface of the aluminum rotor 4 and the DLC coating 16 is applied as the carbon-based material on the nickel coating 15 has been described. A coating of a system material, such as carbon powder, may be provided on the nickel coating 15 coating. Further, a diamond material coating may be applied on the nickel coating 15 instead of the carbon material.

  In the above embodiment, the screw groove 23 is formed on the inner peripheral surface of the screw pump stator 22, and the outer peripheral surface of the rotor 4 facing the screw groove 23 is formed on a smooth cylindrical surface. That is, the inner peripheral surface of the screw pump stator 22 may be a smooth cylindrical surface, and a screw groove may be formed on the outer peripheral surface of the rotor 4 facing the cylindrical surface, or the inner peripheral surface of the screw pump stator 22 is opposed to the inner surface. You may form a screw groove in both the outer peripheral surfaces of the rotor 4. FIG.

Sectional drawing of one Embodiment of the vacuum pump which concerns on this invention. The A section enlarged view of FIG. BB sectional drawing of FIG. Sectional drawing of other embodiment of the vacuum pump which concerns on this invention. Sectional drawing of the conventional vacuum pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior case 1-1 Pump case 1-2 Pump base 2 Intake port 3 Exhaust port 4 Rotor 4a Upper end part of rotor 4-1 Boss part 5 Rotor shaft 5a Rotor shaft upper end 5-1 Rotor shaft small diameter part 6 Partition stage 7 Through-hole 8 Fastening portion 9 of rotor and rotor shaft Fastening bolt 10 Stator column 11 Bearing 12 Rotation drive motor 12-1 Stator 12-2 Rotor 13 Coating on outer peripheral surface of rotor shaft 14-1 Coating on inner peripheral surface of stator column 14-2 High Thermal Conductivity Member 15 Nickel Coating 16 DLC Coating 17 Radial Magnetic Bearing 17-1 Radial Electromagnet Target 17-2 Radial Electromagnet 17-3 Radial Direction Displacement Sensor 18 Axial Magnetic Bearing 18-1 Armature Disk 18-2 Axial Electromagnet 18 -3 Axial direction displacement sensor 19 Rotor blade 19-1 Top stage Rotor blade 19-2 Lowermost rotor blade 20 Stator blade 20-1 Uppermost stator blade 20-2 Lowermost stator blade 21 Blade fixed spacer 22 Screw pump stator 22a Screw pump stator upper end 22b Screw pump stator lower end 23 Screw groove 23a Thread groove upstream end 23b Thread groove downstream end 24 Cooling pipe 25 Insertion hole 26 Molding part 27 Gutter part Pt Turbo molecular pump Ps Screw pump

Claims (12)

A cylindrical rotor housed in an outer case having an air inlet and an air outlet;
A rotor shaft disposed inside the rotor and fastened to an axis of the rotor;
A bearing that rotatably supports the rotor shaft around its axis;
A rotational drive motor for rotating the rotor shaft;
A stator column that is provided in a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft, and that houses pump interior components such as the bearing and the rotary drive motor;
A transfer compression means is provided between an outer peripheral surface of the rotor and a surface facing the rotor, and compresses the gas molecules while transferring the gas molecules from the intake port side to the exhaust port side by rotation of the rotor. And
The rotor has rotor blades on its outer peripheral surface,
The above-mentioned rotor and rotor blade are composed of an aluminum alloy base material and a carbon-based coating thereon provided with an intermediate layer of a different material from the aluminum alloy or carbon-based material.   The vacuum pump according to claim 1, wherein the intermediate layer is a layer made of a metal-based material.   The vacuum pump according to claim 2, wherein the metallic material is a nickel material.   2. The vacuum pump according to claim 1, wherein the intermediate layer is an aluminum oxide layer formed by oxidizing the base material of the aluminum alloy.   The vacuum pump according to claim 1, wherein the intermediate layer is a ceramic layer.   The vacuum pump according to claim 1, wherein the intermediate layer is a layer made of a resin material.   The vacuum pump according to claim 1, wherein the carbon-based film is DLC. The vacuum pump further includes:
The vacuum pump according to claim 1, wherein an inner peripheral surface of the stator column facing an outer peripheral surface of the rotor shaft is covered with a coating made of a material having a higher emissivity. The vacuum pump further includes:
A high thermal conductivity member made of a material having a higher thermal conductivity is exposed on the inner peripheral surface of the stator column facing the outer peripheral surface of the rotor shaft, and the exposed surface of the high thermal conductivity member is The vacuum pump according to claim 1, wherein the vacuum pump is covered with a film made of a substance having a high emissivity. A cylindrical rotor housed in an outer case having an air inlet and an air outlet;
A rotor shaft disposed inside the rotor and fastened to an axis of the rotor;
A bearing that rotatably supports the rotor shaft around its axis;
A rotational drive motor for rotating the rotor shaft;
A stator column that is provided in a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft, and that houses pump interior components such as the bearing and the rotary drive motor;
A transfer compression means provided between an outer peripheral surface of the rotor and a surface facing the rotor, and compressing gas molecules while transferring the gas molecules from the intake port side to the exhaust port side by rotation of the rotor;
A bypass portion for heat conduction from the rotor to the rotor shaft side;
The bypass section is
The rotor shaft small diameter portion provided on the shaft upper end surface of the rotor shaft is inserted into the through hole of the partition step provided inside the upper end portion of the rotor, and in this state, the through hole strongly tightens the rotor shaft small diameter portion. A vacuum pump characterized by a shaft fitting structure by shrink fitting. A cylindrical rotor housed in an outer case having an air inlet and an air outlet;
A rotor shaft disposed inside the rotor and fastened to an axis of the rotor;
A bearing that rotatably supports the rotor shaft around its axis;
A rotational drive motor for rotating the rotor shaft;
A stator column that is provided in a space between the inner peripheral surface of the rotor and the outer peripheral surface of the rotor shaft, and that houses pump interior components such as the bearing and the rotary drive motor;
A transfer compression means provided between an outer peripheral surface of the rotor and a surface facing the rotor, and compressing gas molecules while transferring the gas molecules from the intake port side to the exhaust port side by rotation of the rotor;
A bypass portion for heat conduction from the rotor to the rotor shaft side;
The bypass section is
A boss portion is integrally formed as a part of the rotor on the lower surface of the partition step provided inside the upper end portion of the rotor, and an insertion hole for the boss portion is formed on the upper end surface of the rotor shaft. A vacuum pump comprising a structure in which the boss portion, which is a part of the rotor, is inserted into an insertion hole in an upper end surface of the shaft. The vacuum pump according to any one of claims 1, 10, and 11,
A vacuum pump characterized in that the bearing comprises a magnetic bearing.

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