JP2007107480A - Turbo vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbo vacuum pump having pump discharge characteristics capable of corresponding to a large quantity of gas discharge by rotating a rotary blade of a pump at high speed and enabling continuous operation under a thigh temperature condition, and capable of performing heat-up operation for preventing formation of reaction secondary product. <P>SOLUTION: The turbo vacuum pump 101A is provided with a suction part 1a sucking gas in an axial direction, an exhaust part L including a rotary blade 5 and a fixed blade 8 discharging gas sucked by the suction part 1a, and a rotary shaft 4 rotating the rotary blade. The rotary blade includes a boss part 16 connected to the rotary shaft and cylindrical parts 17a, 17b projecting from the boss part 16 in an axial direction. The boss part and the cylindrical part are composed of metal matrix composite using porous ceramics and aluminum alloy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a turbo vacuum pump that evacuates gas to form a vacuum, and more particularly, to a turbo vacuum pump that is suitable for operation in which a high temperature region is generated in a rear stage.

  FIG. 9 shows a conventional turbo vacuum pump 201A. In the turbo vacuum pump 201A, an exhaust part L composed of a blade exhaust part L1 and a groove exhaust part L2 is constituted by a rotor (rotating part) R and a stator (fixed part) S inside a cylindrical pump casing 101. Yes. The upper part of the pump casing 101 is formed with an intake port 101a for sucking gas, and the lower part of the pump casing 101 is covered with a pump base part 102. The pump base part 102 is formed with an exhaust port 120 for exhausting gas. Yes. The stator S is mainly composed of a fixed cylindrical portion 103 erected at the center of the pump base portion 102 and fixed side portions of the blade exhaust portion L1 and the groove exhaust portion L2.

The rotor R is composed of a rotating shaft 104 inserted into the fixed cylindrical portion 103 and a rotating blade 105 attached to the rotating shaft 104 with a bolt 122. Rotating blades 112 are integrally provided on the upper and lower outer circumferences of the rotating blades 105 to form an impeller. On the inner surface of the pump casing 101, fixed blades 171 having fixed blades 113 arranged alternately with the rotating blades 112 are provided. When the rotor blade 105 is provided and rotates at high speed, gas is exhausted by the interaction between the rotor blade 105 and the stationary blade 171 that is stationary. The rotating shaft 104 rotates the rotating blade 105, and the rotating blade 112 is rotated by the rotation of the rotating blade 105.
JP 2001-059496 A

  Needless to say, the exhaust performance of the turbo vacuum pump should be such that the rotor blades are rotated as fast as possible. However, the centrifugal force acting on the rotor blades is significantly increased by increasing the rotational speed. For this reason, a high-strength aluminum alloy that is lightweight and has high strength, that is, high specific strength (ratio of strength and material density) is used as the material of the rotor blades. However, the aluminum alloy has low heat resistance, and the mechanical properties deteriorate at about 130 ° C. or higher. Therefore, it is necessary for the turbo type vacuum pump to limit the operation range so that the temperature of the rotor blades becomes a predetermined temperature (for example, 120 ° C.) or less during operation. As a result, there is a problem that a large amount of gas cannot be exhausted continuously. It was.

  In addition, when a turbo vacuum pump is used in a semiconductor manufacturing apparatus or the like that generates reaction by-products during the process, the temperature of the gas flow path in the pump is increased in order to prevent reaction by-product precipitation in the pump. However, it is difficult to increase the temperature to about 130 ° C. or higher due to the temperature limitation of the rotary blade described above. For this reason, there has been a problem that a turbo vacuum pump cannot be applied to a process in which reaction by-products are deposited.

  Therefore, in view of the above points, the present invention has a pump exhaust performance that can handle a large amount of gas exhaust by rotating the rotor blades of the pump at a high speed and enabling continuous operation in a high temperature state. And it aims at providing the turbo-type vacuum pump which can perform heat-up operation in order to prevent precipitation of a reaction by-product.

  In order to achieve the above object, a turbo vacuum pump 101A according to the invention according to claim 1 includes an intake portion 1a for sucking gas in the axial direction, as shown in FIGS. 1 and 2, for example; An exhaust portion L having a rotating blade 5 and a fixed blade 8; and a rotating shaft 4 for rotating the rotating blade 5; the rotating blade 5 includes a boss portion 16 connected to the rotating shaft 4, and a boss portion 16. It has cylindrical portions 17a and 17b projecting in the axial direction; the boss portion 16 and the cylindrical portions 17a and 17b are made of a metal matrix composite material using porous ceramics and an aluminum alloy.

  When the boss part and the cylindrical part of the rotor blade are made of a metal matrix composite material using porous ceramics and an aluminum alloy, the material has high specific strength and excellent heat resistance. The metal matrix composite material will be used in parts where large centrifugal stress acts when the rotor blades rotate at high speed, enabling the pump rotor blades to rotate at high speeds and enabling continuous operation at high temperatures. Therefore, it is possible to provide a turbo vacuum pump having a pump exhaust performance capable of accommodating a large amount of gas exhaust and capable of performing a heat-up operation in order to prevent precipitation of reaction byproducts.

  In order to achieve the above object, a turbo vacuum pump 101B according to claim 2 includes, for example, an intake portion 23A that sucks gas in the axial direction as shown in FIGS. 4, 6, and 7; An exhaust part 50 having rotor blades 73 and 24 for exhausting and fixed blades 71 and 28; a rotating shaft 21 for rotating the rotor blades 73 and 24; and the rotor blades 73 and 24 supplying the sucked gas to the shaft One or more turbine blades 73 that exhaust in the direction, and one or more centrifugal blades 24 that are located on the downstream side of the turbine blade 73 and exhaust the exhausted gas by centrifugal drag action. The turbine blade 73 has a boss portion 74 connected to the rotating shaft 21 and a cylindrical portion 52 projecting axially from the boss portion 74 of the turbine blade 73; the centrifugal blade 24 is connected to the rotating shaft 21; Boss 61 and centrifugal blade A boss portion 74 of the turbine blade 73, a cylindrical portion 52, a boss portion 61 of the centrifugal blade 24, and the disk portion 27. And a metal matrix composite material using porous ceramics and an aluminum alloy.

  If the boss part of the turbine blade, the cylindrical part, the boss part of the centrifugal blade, and the disk part are made of a metal matrix composite material using porous ceramics and an aluminum alloy, both the turbine blade and the centrifugal blade The metal matrix composite material, which has a large specific strength due to the characteristics of the material and is excellent in heat resistance, is used for a portion where a large centrifugal stress acts when the rotor blades rotate at a high speed. In order to prevent pumping of reaction by-products and to have a pump exhaust performance that can handle a large amount of gas exhaust by rotating the rotor blades at high speed and enabling continuous operation at high temperatures It can be set as the turbo type vacuum pump which can perform a heat-up driving | operation.

  A turbo vacuum pump according to claim 3 is the turbo vacuum pump according to claim 1 or 2, wherein the outer surface of the rotor blade is formed of only an aluminum alloy.

  If comprised in this way, since the outer surface of a rotary blade becomes only an aluminum alloy, various surface treatment constructions (for example, electroless Ni plating etc.) will become easy. Thereby, a turbo type vacuum pump with high corrosion resistance can be easily provided.

  A turbo type vacuum pump according to a fourth aspect is the turbo type vacuum pump according to the third aspect, wherein the outer surface of the rotor blade is subjected to a surface treatment.

  As described above, according to the turbo type vacuum pump of the present invention, the rotor blade has the boss portion connected to the rotating shaft and the cylindrical portion projecting in the axial direction from the boss portion, and the boss portion Since the cylindrical portion is made of a metal matrix composite material using porous ceramics and an aluminum alloy, the metal matrix composite is a material having a large specific strength and excellent heat resistance. A large amount of material will be used for the part where large centrifugal stress acts by rotating the rotor blade at high speed, and by rotating the rotor blade of the pump at high speed and enabling continuous operation at high temperature. A turbo-type vacuum pump having a pump exhaust performance capable of coping with gas exhaust and capable of performing a heat-up operation in order to prevent precipitation of reaction by-products can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a front cross-sectional view showing a configuration of a turbo vacuum pump 101A according to a first embodiment of the present invention. Currently, there is a turbo-molecular pump as a kind of turbo-type vacuum pump that is widely used for semiconductor processes such as semiconductor manufacturing equipment.

  This will be described below with reference to the drawings. The turbo type vacuum pump 101A is composed of a blade exhaust part L1 and a groove exhaust part L2 by a rotor (rotating part) R and a stator (fixed part) S inside a cylindrical pump casing 1 arranged vertically above and below. An exhaust portion L is configured. The lower part of the pump casing 1 is covered with a pump base 2, and the pump base 2 is formed with an exhaust port 20 communicating with the exhaust side of the groove exhaust part L2. In the upper part of the pump casing 1, an intake port 1 a as an intake portion for sucking gas in the axial direction is configured, and a flange 81 is provided for connecting to a device and piping to exhaust the gas. The stator S is mainly composed of a fixed cylindrical portion 3 erected at the center of the pump base 2 and fixed side portions of the blade exhaust portion L1 and the groove exhaust portion L2.

  The rotor R is composed of a rotating shaft 4 inserted into the fixed cylindrical portion 3 and a rotating blade 5 attached to a tip 4 a on the intake portion side of the rotating shaft 4 with a bolt 22. The fixed cylindrical portion 3 is accommodated in a cylindrical portion 17b of the rotary blade 5 on the side of the anti-intake portion described later. A drive motor 6 and an upper radial bearing 7a and a lower radial bearing 7b are provided above and below the drive motor 6 between the rotary shaft 4 and the fixed cylindrical portion 3. An axial bearing 11 having a target disk 9 at the lower end of the rotating shaft 4 and upper and lower electromagnets 10a and 10b on the stator S side is disposed below the rotating shaft 4. With such a configuration, the rotor R rotates at high speed while receiving active control of five axes.

  Eight stages of rotary blades 12 are integrally provided on the upper and lower outer peripheries of the rotary blades 5 to form an impeller. On the inner surface of the pump casing 1, fixed blades 8 having fixed blades 13 arranged alternately with the rotary blades 12 are provided. The fixed wing 8 is composed of eight stages. When the rotating blade 5 rotates at a high speed, gas is exhausted in the axial direction by the interaction between the rotating blade 5 and the stationary stationary blade 8, and the rotating blade 5 and the stationary blade 8 constitute the blade exhaust portion L1. is doing. The fixed wing 8 is fixed with its peripheral edge pressed from above and below by a fixed wing spacer 14. The rotating shaft 4 rotates the rotating blade 5, and the rotating blade 12 rotates as the rotating blade 5 rotates.

  Further, a groove exhaust portion L2 is provided below the blade exhaust portion L1. That is, the stator S is provided with a thread groove spacer 19 surrounding the outer periphery of the rotor R, and the thread groove spacer 19 is formed with a thread groove 19a. The groove exhaust portion L2 exhausts by the drag action of the screw groove 19a facing the rotor R rotating at high speed.

  Next, the configuration of the rotary blade 5 will be described in more detail with reference to FIG. The rotary blade 5 is a portion that is fastened and connected to the rotary shaft 4 (FIG. 1), and is formed integrally with the boss portion 16 from the boss portion 16 in the axial intake portion 1a (FIG. 1) direction. It has a cylindrical portion 17a that protrudes and a cylindrical portion 17b that is formed integrally with the boss portion 16 and protrudes from the boss portion 16 in the axial anti-intake portion direction, and has a substantially bell shape. A through hole 82 through which the bolt 22 (FIG. 1) passes is formed in the boss part 16, the bolt 22 passes through the through hole 82 of the boss part 16, and the rotary blade 5 is fastened to the rotary shaft 4 by the bolt 22. (FIG. 1). The rotating blades 12 are attached to the outer periphery of the boss portion 16 and the outer periphery of the cylindrical portions 17a and b, and the boss portion 16 and the cylindrical portions 17a and b are portions where large centrifugal stress acts on the rotary blade 5 due to high-speed rotation. is there.

  The boss portion 16 and the cylindrical portions 17a and b are made of a metal composite material using porous ceramics and an aluminum alloy (in the drawing, the outside of the portion indicated by the broken line is formed only from the aluminum alloy). Thereby, since the allowable centrifugal stress of the rotary blade 5 is improved, high speed rotation is possible. Moreover, since the strength reduction at the time of increasing the temperature can be suppressed, the temperature of the rotor blade 5 can be increased, for example, the allowable use temperature can be increased from the conventional 120 ° C. to 250 ° C. Therefore, the turbo vacuum pump 101A (FIG. 1) is suitable for an operation in which a high temperature region of 250 ° C. or less is generated in the rear stage.

  Next, the rotary blade 12 of the rotary blade 5 will be described with reference to FIGS. These are plan views of the rotary blades as viewed from the intake side. FIG. 3A is a view of the first-stage rotary blade 12 in the direction of arrow A (FIG. 2), and FIG. B of the rotary blade 12 of FIG. 2 (FIG. 2), FIG. 3C shows the C blade of the third stage rotary blade 12 (FIG. 2), and FIG. D (FIG. 2) and FIG. 3 (e) are E arrows (FIG. 2) of the sixth stage rotating blade 12. FIG. The fifth stage rotary blade 12 has the same configuration as the fourth stage rotary blade 12, and the seventh stage rotary blade 12 and the eighth stage rotary blade 12 have the same configuration as the sixth stage rotary blade 12. is there. The figure which expand | deployed the front-end | tip part of the rotary blade 12 which looked at the rotary blade 12 radially from the top is also shown. The rotary blade 12 is attached with a twist angle twisted by a certain angle from the central axis of the rotary shaft 4.

  Returning to FIG. 2, the description will be continued. The turbo vacuum pump 101A (FIG. 1) often exhausts a highly corrosive gas, for example, a halogen-based gas such as fluorine or chlorine. If such a strong corrosive gas is exhausted and the aluminum alloy is attacked, the impeller is destroyed by stress corrosion cracking. In order to prevent this, the surface may be subjected to a corrosion resistance treatment (for example, electroless Ni plating). However, a metal matrix composite material simply formed of porous ceramics and an aluminum alloy is inferior in surface treatment workability (for example, in an electroless Ni plating, adhesiveness and throwing power) as compared with an aluminum alloy.

  Therefore, in order not to impair the workability of the surface treatment, the metal matrix composite material is externally attached so that only the aluminum alloy exists on the outer surface of the metal matrix composite material using the porous ceramics and the aluminum alloy. It is assumed that an aluminum alloy layer is formed on the surface. For this purpose, the entire circumference of the porous ceramic is formed so as to be covered by pressure casting using an aluminum alloy. That is, the portion of the rotor blade 5 excluding the rotor blade 12 (the boss part 16 and the cylindrical parts 17a and 17b) is formed of porous ceramics, and then aluminum is formed on the outer surfaces of the boss part 16 and the cylindrical parts 17a and 17b. An alloy layer is formed by pressure casting, and at the same time, an aluminum alloy material (not shown) of the rotating blade 12 is formed by pressure casting on the portion of the rotating blade 12. Thereafter, the rotary blade 12 is cut out from the material of the rotary blade 12 by machining (for example, end milling). Thereafter, the boss portion 16, the cylindrical portions 17 a and 17 b, and the surfaces of the rotary blades 12 can be subjected to corrosion resistance treatment (for example, electroless Ni plating).

  A metal matrix composite material using porous ceramics and an aluminum alloy has a high specific strength due to the characteristics of the material and is excellent in heat resistance. Therefore, by adopting the metal matrix composite material in a portion where a large centrifugal stress acts when the rotor blade 5 rotates at a high speed, that is, in the boss portion 16 and the cylindrical portions 17a and 17b fastened to the rotating shaft 4. Since the use limit temperature of the rotor blade 5 can be increased, the tolerance increases with respect to the rotor temperature rise due to a large amount of gas exhaust. Moreover, since the heat-up temperature of the pump exhaust passage can be set high, it is possible to provide a turbo type vacuum pump that prevents precipitation of reaction byproducts and has high resistance to the reaction byproducts. Here, the heat-up temperature refers to the temperature of the gas exhausted in the pump exhaust passage during the heat-up operation. The heat-up operation here means that the inside of the pump exhaust passage is heated by a heating means such as a heater, and the exhaust gas is exhausted while being heated and held at 130 to 250 ° C.

  Note that a wing part (blade) (for example, a wing part of a turbine blade, that is, a turbine blade) is formed on the outer peripheral side of the boss part 16 and the cylindrical parts 17a and 17b. It is smaller than that of the part 16 and the cylindrical parts 17a and 17b. Therefore, it is preferable to form the wing portion with only an aluminum alloy in consideration of weight reduction of the wing portion for reducing centrifugal stress acting on the boss portion 16 and the cylindrical portions 17a and 17b and ease of wing processing.

As the material for the porous ceramic, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), and alumina (Al ₂ O ₃ ) are often used. The porous ceramic is previously formed by pressure casting of an aluminum alloy so that the porous ceramic in the composite material after casting has a ratio of 30 to 70 Vol%.
In addition, an aluminum alloy used for pressure casting is generally an Al-Si alloy (silmine), which is characterized by good fluidity of the molten metal. In order to improve the mechanical properties without impairing the castability, magnesium (Mg) or copper (Cu) may be added.

  FIG. 4 is a front sectional view showing a configuration of a turbo vacuum pump 101B according to the second embodiment of the present invention. Hereinafter, a description will be given with reference to the drawings. The turbo vacuum pump 101B is a vertical type and includes an exhaust unit 50, a motion control unit 51, a rotating shaft 21, and a casing 53 that houses the exhaust unit 50, the motion control unit 51, and the rotating shaft 21. The rotating shaft 21 is disposed vertically above and below, and has an exhaust part side part 21A on the exhaust part 50 side and a motion control part side part 21B on the motion control part 51 side.

  The casing 53 includes an upper housing (pump stator) 23, a lower housing 37 disposed below the upper housing 23 in the vertical direction (axial direction of the turbo vacuum pump 101B), and between the upper housing 23 and the lower housing 37. And a sub-casing 40 disposed on the surface. The upper housing 23 has an intake nozzle 23A as an intake portion formed at the uppermost portion, and the sub casing 40 has an exhaust nozzle 23B formed on a side surface. A flange portion 83 is formed in the upper portion of the upper housing 23, and a bolt hole 83 </ b> A is formed in the flange portion 83. The upper housing 23 accommodates the exhaust part 50 and the exhaust part side part 21 </ b> A on the exhaust part 50 side of the rotary shaft 21. The intake nozzle 23A sucks a gas as a fluid (for example, a corrosive process gas or a gas containing a reaction product) vertically downward, and the exhaust nozzle 23B exhausts the sucked gas horizontally.

The exhaust section 50 includes five stages of fixed blades 71 and 28, three stages of turbine blades 75, turbine blades 73 (three stages of turbine blades) as rotor blades, and three stages of centrifugal blades as rotor blades. And a wing (centrifugal drag wing) 24.
The fixed blade 71 is composed of three stages and is arranged on the flow side immediately after the turbine blade 75. The fixed wing 71 includes an annular ring part 76 and plate-like blades 77 attached radially to the outer periphery of the annular part 76. An inner peripheral portion of the annular portion 76 forms a shaft hole 60, and a cylindrical portion 52 and a boss portion 74 described later of the turbine blade 73 pass through the shaft hole 60. The blades 77 are attached with a twist angle twisted by, for example, 10 to 40 degrees from the extended central axis of the rotary shaft 21.
The fixed vane 28 has two stages and is arranged on the flow side immediately after the first and second stage centrifugal vanes 24. The fixed wing 28 includes an outer peripheral wall 62, a side wall 63, and a spiral guide 29 having a spiral shape that protrudes from the intake side surface of the side wall 63.

  A screw hole 18 is formed in the intake portion side end 15 at the top of the rotating shaft 21. A turbine blade 73 is fixedly attached to the intake side end 15 by inserting a hexagon bolt 78 as a screw member into the screw hole 18. The hexagon bolt 78 passes through a through hole 58 described later and is inserted into the screw hole 18. A fitting hole 25 is formed at the center of the centrifugal blade 24. The connection of the rotary shaft 21 of the centrifugal blade 24 will be described. The centrifugal blade 24 is attached in such a manner that the rotary shaft 21 penetrates the fitting hole 25 and is fixed to the rotary shaft 21 by fitting. .

  The lower housing 37 houses the motion control unit 51 and the motion control unit side portion 21B on the motion control unit 51 side of the rotating shaft 21. The motion control unit 51 includes an upper protection bearing 35, an upper radial magnetic bearing 31, a motor 32 that rotationally drives the rotary shaft 21, a lower radial magnetic bearing 33, a lower protection bearing 36, and axial magnetic bearings 34 and 34. Are arranged in this order from the top to the bottom in the vertical direction. The upper radial magnetic bearing 31 and the lower radial magnetic bearing 33 support the rotary shaft 21 in a freely rotatable manner. The axial magnetic bearings 34 and 34 support the force due to the weight of the rotating body in the downward direction in the figure and the thrust force in the vertical direction in the figure.

  Each of the magnetic bearings 31, 33, 34 is an active magnetic bearing. When an abnormality occurs in any of the magnetic bearings 31, 33, 34, the upper protective bearing 35 supports the rotary shaft 21 in the radial direction of the rotary shaft 21 instead of the upper radial magnetic bearing 31, and the lower protective bearing 36 Instead of the lower radial magnetic bearing 33 and the axial magnetic bearing 34, the rotary shaft 21 is supported in the radial direction and the axial direction of the rotary shaft 21.

  As shown in FIGS. 5 (a) and 5 (b), the upper housing 23 is formed of porous ceramics (inside the portion indicated by a broken line in the figure), and then the entire material formed of porous ceramics ( An aluminum alloy layer covering the outer surface is formed by pressure casting. As a result, the weight of the upper casing 23 can be reduced, the weight of the entire pump can be reduced, and the transportation and installation of the pump can be facilitated.

  The configuration of the turbine blade 73 will be described with reference to FIG. The turbine blade 73 has a boss portion 74 fitted and connected to the rotating shaft 21 (FIG. 4), and a cylindrical portion 52 projecting from the boss portion 74 in the axial direction toward the intake portion side. The turbine blade 73 further includes plate-shaped three-stage turbine blades 75 that are radially attached to the outer peripheral portion of the boss portion 74 and the cylindrical portion 52. A through hole 58 through which the hexagon bolt 78 (FIG. 4) passes is formed in the boss portion 74. The turbine blade 75 is attached with a twist angle twisted by, for example, 10 to 40 degrees from the central axis of the rotating shaft 21.

  The configuration of the centrifugal blade 24 will be described with reference to FIGS. 7 (a), (b), and (c). FIG. 7A is a plan view of the first stage centrifugal blade 24 as viewed from the intake nozzle 23A (FIG. 4) side, and FIG. 7B is a front sectional view. The first-stage centrifugal blade 24 includes a substantially disc-shaped base portion 27 having a boss portion 61 as a disc portion, and a spiral blade 26 fixed on a surface 27A that is one surface of the base portion 27. Have. The base portion 27 has a structure that projects from the boss portion 61 in the axial radial direction. The direction of rotation of the centrifugal blade 24 is the clockwise direction in FIG.

  The spiral blade 26 is composed of, for example, six blades having a spiral shape as shown in FIG. The spiral blade 26 has a structure extending in the gas flow direction backward (opposite to the rotation direction) with respect to the rotation direction. The aforementioned fitting hole 25 is formed in the boss portion 61. The configuration of the second-stage and third-stage centrifugal blades 24 (not shown in FIGS. 7A and 7B) is the same as the configuration of the first-stage centrifugal blade 24, but the number of spiral blades 26 is the same. The shape, the outer diameter of the boss portion 61, and the length of the flow path formed by the spiral blades 26 may be appropriately changed.

  As shown in FIG. 7C, the boss portion 61 and the substantially disc-shaped base portion 27 are formed of porous ceramics (inside the portion indicated by the broken line), and cover the boss portion 61 and the base portion 27. An aluminum alloy layer is pressure cast on the portion, and the material of the spiral blade 26 (aluminum alloy) is pressure cast. The boss portion 61 and the substantially disc-shaped base portion 27 are formed of a metal matrix composite material using porous ceramics and an aluminum alloy. This is because centrifugal stress due to rotation acts greatly.

Next, the operation of the turbo vacuum pump 101B will be described with reference to FIGS.
As the first stage turbine blade 73 rotates, gas is introduced from the intake nozzle 23A in the axial direction in FIG. By using the turbine blade 73, the exhaust speed can be increased, and a relatively large amount of gas can be exhausted. The introduced gas is decelerated by the fixed wing 71 and the pressure rises. Similarly, the second stage and third stage turbine blades 73 and stationary blades 71 are exhausted in the axial direction due to the interaction between them, and the pressure rises.

  Next, the first stage centrifugal blade 24 rotates to introduce gas in the axial direction. The gas introduced into the first stage centrifugal blade 24 is caused by the interaction between the first stage centrifugal blade 24 and the first stage fixed blade 28, that is, the drag action due to the viscosity of the gas, and the rotation of the centrifugal blade 24. By the centrifugal action (centrifugal drag action), the gas is compressed and exhausted along the surface 27A of the base 27 of the first stage centrifugal blade 24 toward the outer diameter side of the first stage centrifugal blade 24.

  That is, the gas introduced into the first-stage centrifugal blade 24 is introduced into the centrifugal blade 24 in the substantially axial direction 64 in FIG. 7B and the spiral blade 26 of the first-stage centrifugal blade 24. Flows in the direction toward the outer diameter side through the flow path 68 formed between the two, and is compressed and exhausted. The direction of this gas flow is the direction 65 shown in FIGS. 7A and 7B, and this direction is the direction of gas flow with respect to the first stage centrifugal blade 24.

  The gas compressed toward the outer diameter side by the first-stage centrifugal blade 24 flows into the first-stage fixed blade 28, and is substantially omitted in FIG. 7B by the inner peripheral portion 62A of the outer peripheral wall 62. The direction is changed in the axial direction and flows into the space in which the spiral guide 29 is provided. When the first stage centrifugal blade 24 rotates, the drag action due to the gas viscosity between the end surface 29A of the spiral guide 29 of the fixed blade 28 and the back surface 27B of the base 27 of the first stage centrifugal blade 24 results in 1 Compression and exhaust of gas along the surface 63A of the side wall 63 of the fixed blade 28 at the stage (the surface of the side wall 63 to which the spiral guide 29 is attached) toward the inner diameter side of the fixed blade 28 at the first stage. Is done. The gas that has reached the inner diameter side of the first stage fixed vane 28 changes its direction in the substantially axial direction 64 in FIG. 7B due to the outer peripheral surface 61A of the boss portion 61 of the first stage centrifugal vane 24. It is introduced into the centrifugal blade 24 at the stage. The same compression and exhaustion are performed, and the gas is discharged from the exhaust nozzle 23B through the third stage centrifugal blade 24. The intake pressure is a low pressure region of 1 to 1000 Pa, and the exhaust pressure is a high pressure region of 100 Pa to atmospheric pressure.

  In the turbo vacuum pump 101B of the present embodiment, a turbo vacuum pump 101B is configured by combining a turbine blade 73 having high exhaust efficiency on a relatively low pressure side and a centrifugal blade 24 having high exhaust efficiency on a relatively high pressure side. Since it comprises, exhaust efficiency can be made high in the whole pump. Further, since the centrifugal blade 24 exhausts gas in the radial direction, the axial length can be shortened. Therefore, since the axial length of the rotating shaft portion (the turbine blade 73 and the rotating shaft 21) can be shortened, the natural frequency of the entire rotor can be increased, and high-speed rotation is easy. Further, both the turbine blade 73 and the rotor blades of the centrifugal blade 24 can set the inner diameter of the boss portion 61 to be smaller than that of the rotor blade 5 (FIG. 1) of the turbo vacuum pump 101A shown in the first embodiment. For this reason, the centrifugal stress acting by rotation is reduced, which is suitable for high-speed rotation. By using a metal matrix composite material using porous ceramics and an aluminum alloy for the rotor blades 73 and 24 of such a turbo type vacuum pump 101B, further high speed rotation is possible, and a turbo type with extremely high exhaust efficiency. A vacuum pump 101B can be provided.

  In addition, the turbo vacuum pump 101B according to the present embodiment has a motion by disposing the exhaust control unit 50 including the rotor blades 73 and 24 and the motion control unit 51 including the bearings and the motor 32 in the axial direction. Without considering the thermal influence of the control unit 51, the temperature of the exhaust unit 50 can be determined only by the allowable temperature of the rotor blades 73 and 24. Therefore, by increasing the allowable temperature of the rotor blades 73 and 24, it is possible to set the temperature of the exhaust unit 50 high, and the turbo vacuum pump 101B is less likely to generate reaction by-products. It is possible to provide a turbo vacuum pump 101B suitable for an operation in which the above occurs.

  A metal matrix composite material formed of porous ceramics and an aluminum alloy has high specific strength due to the characteristics of the material and excellent heat resistance. Therefore, the metal matrix composite material is subjected to a portion where a large centrifugal stress acts as the rotating blades 73 and 24 rotate at high speed, that is, the boss portion 74 of the turbine blade 73 connected to the rotating shaft 21, the cylindrical portion 52, and the rotating shaft. 21. Since the use limit temperature of the rotor blades 73 and 24 can be increased by adopting the boss portion 61 and the base portion 27 of the centrifugal blade 24 connected to the rotor 21, the tolerance to the rotor temperature rise due to a large amount of gas exhaust is provided. growing. In addition, since the heat-up temperature of the pump exhaust passage can be set high (130 to 250 ° C.), precipitation of reaction by-products can be prevented and the turbo vacuum pump 101B having high resistance to the reaction by-products can be obtained. Can be provided.

  FIGS. 8A to 8D are diagrams showing an example of a method for forming the turbine blade 73 used in the turbo vacuum pump 101B (FIG. 4) shown in the second embodiment. The turbine blade 73 of the present embodiment has a three-stage blade configuration as described above.

First, as shown in FIG. 8A, aggregates 84A, B, and C, which are materials of the boss portion 74 and the cylindrical portion 52, are manufactured in a single stage using porous ceramics. In portions corresponding to the cylindrical portion 52 and the boss portion 74 of the aggregates 84A, B, and C, fitting portions 85 to 88 for stacking the plurality of aggregates 84A, B, and C are formed. Then, as shown in FIG. 8B, a plurality of aggregates 84A, B, and C are fitted and fixed by fitting portions 85 to 88 to form a three-stage configuration. Thereafter, as shown in FIG. 8 (c), an aluminum alloy layer covering the entire inner periphery, outer periphery, and side portions (outer surface) of the aggregates A, B, and C is provided by pressure casting. By providing a portion of the aluminum alloy material corresponding to the turbine blade 75 by pressure casting, a metal matrix composite material using porous ceramics and an aluminum alloy is formed. Finally, the turbine blades 75 installed on the outer peripheral portions of the boss portion 74 and the cylindrical portion 52 are formed by machining to manufacture the turbine blades 73. As a result, a multistage integrated wing can be easily manufactured using porous ceramics which are difficult to process (FIG. 8D). Then, it is good to give corrosion resistance processing (for example, electroless Ni plating etc.) to each surface of the boss | hub part 74, the cylindrical part 52, and the turbine blade 75.
Needless to say, the above-described manufacturing method may be used for the rotor blade 5 (FIG. 1) shown in the first embodiment.

It is front sectional drawing of the turbo type vacuum pump which concerns on the 1st Embodiment of this invention. It is front sectional drawing of the rotary blade of the turbo type vacuum pump of FIG. It is an arrow view of the arrow view shown in FIG. (A) is an arrow A view, (b) is an arrow B view, (c) is an arrow C view, (d) is an arrow D view, and (e) is an arrow E view. It is front sectional drawing of the turbo type vacuum pump which concerns on the 2nd Embodiment of this invention. It is a fragmentary sectional view of the upper housing of the turbo type vacuum pump of FIG. (A) is a partial plane sectional view, (b) is a partial front sectional view. It is a partial front sectional view of the turbine blade of the turbo type vacuum pump of FIG. (A) is a top view of the centrifugal blade of the turbo type vacuum pump of FIG. 4, (b) is the same front sectional view, (c) is the same partial front sectional view. (A) is each front sectional drawing before assembling the aggregate of the turbine blade of the turbo type vacuum pump of FIG. 4, (b) is front sectional drawing which assembled the aggregate, (c) is aggregate. FIG. 5D is a front sectional view of a turbine blade material manufactured by pressure casting, and FIG. 6D is a front sectional view after processing a blade portion of the turbine blade material. It is front sectional drawing of the conventional turbo type vacuum pump.

Explanation of symbols

1 Pump casing 1a Intake port (intake part)
2 Pump base portion 3 Fixed cylindrical portion 4 Rotating shaft 5 Rotating blade 8 Fixed wing 12 Rotating blade 13 Rotating blade 13 Fixed blade 16 Boss portion 17a, 17b Cylindrical portion 19 Thread groove spacer 19a Thread groove 20 Exhaust port 21 Rotating shaft 22 Bolt 23 Upper housing 23A Intake nozzle (intake section)
23B Exhaust nozzle 24 Centrifugal blade (rotary blade)
27 Base (disk part)
28 Fixed blade 52 Cylindrical portion 61 Boss portion 71 Fixed blade 73 Turbine blade (rotary blade)
74 Boss part 75 Turbine blade 77 Blade 101A, 101B Turbo type vacuum pump L1 Blade exhaust part L2 Groove exhaust part R Rotor S Stator

Claims (4)

An intake section for sucking gas in the axial direction;
An exhaust section having a rotating blade and a fixed blade for exhausting the sucked gas;
A rotating shaft for rotating the rotating blade;
The rotary blade has a boss part connected to the rotary shaft, and a cylindrical part protruding in the axial direction from the boss part;
The boss portion and the cylindrical portion are made of a metal matrix composite material using porous ceramics and an aluminum alloy;
Turbo vacuum pump. An intake section for sucking gas in the axial direction;
An exhaust section having a rotating blade and a fixed blade for exhausting the sucked gas;
A rotating shaft for rotating the rotating blade;
One or more stages of turbine blades for exhausting the sucked gas in the axial direction, and one stage for exhausting the exhausted gas further by centrifugal drag action Comprising the above centrifugal blades;
The turbine blade includes a boss portion connected to the rotating shaft and a cylindrical portion projecting in an axial direction from the boss portion of the turbine blade;
The centrifugal blade has a boss portion connected to the rotating shaft, and a disk portion protruding in the axial radial direction from the boss portion of the centrifugal blade;
The boss portion of the turbine blade, the cylindrical portion, the boss portion of the centrifugal blade, and the disc portion are made of a metal matrix composite material using porous ceramics and an aluminum alloy;
Turbo vacuum pump. The outer surface of the rotor blade was made of aluminum alloy only;
The turbo type vacuum pump according to claim 1 or 2. The outer surface of the rotor blade is subjected to a surface treatment;
The turbo type vacuum pump according to claim 3.

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