JPWO2012172990A1 - Rotor and vacuum pump - Google Patents

Abstract

By including a cylindrical body having a load change mitigation structure that mitigates the load change at the boundary between the rotor and the cylindrical rotating part, and including the cylindrical body, rotational performance (ie, exhaust performance), reliability, and An object of the present invention is to provide a vacuum pump with improved durability. In a vacuum pump, a load change mitigation that relieves a load change due to thermal stress at a joint where a cylindrical rotating part made of a different material (such as FRP material) is joined to a metal (such as an aluminum alloy) rotating part Provide structure. More specifically, the boundary portion between the rotating portion and the cylindrical rotating portion has any one of a gentle taper, a curved portion and a tapered portion, or a corner R.

Description

  The present invention relates to a rotor and a vacuum pump, and more particularly to a rotor having a load change mitigation structure for mitigating a load change at a joint, and a vacuum pump including the rotor.

Among various vacuum pumps, turbo molecular pumps and thread groove pumps are frequently used to realize a high vacuum environment.
In such a vacuum pump, a structure that allows the vacuum pump to perform an exhaust function is housed in a casing forming an exterior body having an intake port and an exhaust port. The structure that exhibits the exhaust function is roughly divided into a rotating part (rotor part) that is rotatably arranged and a fixed part (stator part) fixed to the casing.
In the case of a turbo-molecular pump, the rotating part is composed of a rotating shaft and a rotating body fixed to the rotating shaft, and the rotating body is provided with radially arranged rotating blades (moving blades) in multiple stages. . In the fixed portion, stator blades (stator blades) are arranged in multiple stages alternately with respect to the rotating blades. Furthermore, the turbo molecular pump is provided with a motor for rotating the rotating shaft at a high speed. When the rotating shaft rotates at a high speed by the function of this motor, gas is sucked from the intake port due to the interaction between the rotating blade and the stator blade. And exhausted from the exhaust port.

In such a vacuum pump such as a turbo molecular pump or a thread groove pump, the rotating part is usually made of a metal such as aluminum or an aluminum alloy.
However, in recent years, for the purpose of improving performance (especially, rotating at a higher speed), a cylindrical rotating part that rotates at a high speed is a lighter and stronger fiber-reinforced composite material (fiber-reinforced plastic material, Fiber Reinforced Plastics (hereinafter referred to as FRP material). In this case, fibers used for the FRP material include aramid fibers (AFRP), boron fibers (BFRP), glass fibers (GFRP), carbon fibers (CFRP), and polyethylene fibers (DFRP).
As described above, when the cylindrical rotating part disposed at the lower part of the rotating part of the vacuum pump is a cylindrical rotating part formed of a light and strong FRP material, the lightening and enlargement of the cylindrical part can be realized. Therefore, the exhaust performance of the vacuum pump in which the cylindrical rotating part is disposed can be improved.
Note that, as shown in FIGS. 9 (a) and 9 (b), a rotating part (rotating blade) made of metal such as an aluminum alloy and a cylindrical rotating part formed of FRP material are generally used as a rotor (rotating). Part) 80 (800) is arranged on the inner side and the cylindrical rotating part 9 is arranged on the outer side, and a guide is provided at the lower part of the rotating part and bonded by means such as press-fitting, bonding, or a combination of press-fitting and bonding. Is done.

Here, the temperature of the rotor of the vacuum pump may rise from room temperature to around 150 ° C. depending on operating conditions. Since it has such a wide temperature range, a large thermal stress is generated due to the difference in thermal expansion between the two types of materials at high temperatures.
Since the aluminum alloy has a thermal expansion coefficient many times higher than that of the FRP material, when the temperature rises with the operation time, the inner metal rotating part expands more and more with the temperature rise. On the other hand, since the cylindrical rotating part formed of the FRP material joined to the outside does not expand so much, very large stress is generated on the contact surface of the joining part during operation.

Patent No. 3098139 JP 2004-278512 A

In Patent Document 1, in a composite molecular pump composed of a turbo molecular pump part and a thread groove pump part, the rotor of the turbo molecular pump part is made of metal, and the cylindrical rotor of the thread groove pump part and the rotor of the turbo molecular pump part are It describes an invention in which the support plate (5) for joining the cylindrical rotors of the thread groove pump part is formed of a fiber reinforced plastic material (FRP).
As described above, in the invention described in Patent Document 1, a member (support) having a thermal expansion coefficient intermediate between the metal and FRP is provided between the metal rotor of the turbo molecular pump unit and the cylindrical rotor formed of FRP. The thermal stress due to the difference in thermal expansion described above is relieved across the plate.
In Patent Document 2, as a method of manufacturing the above-described cylindrical rotating part with FRP material, a filament winding method in which a fiber bundle is wound and hardened with a resin, or fibers are embedded in resin (impregnated in advance). The sheet winding method in which the sheet is wound is described. The filament winding method is made of a composite material of an organic base material based on a resin filled with reinforcing fiber (FRP) such as glass fiber or carbon fiber. The holbeck cart downstream rotor segment (5c) made by continuously winding around a core is described.
As described above, in the invention described in Patent Document 2, the load generated when the fiber is wound obliquely or when the ratio of the resin to the fiber and the resin is set to be larger and spreads from the inside due to thermal expansion. The load in the vicinity of the joint is reduced by devising the winding condition of the FRP, such as intentionally reducing the Young's modulus of the material so that the value becomes small.

However, Patent Document 1 and Patent Document 2 described above are intended to alleviate the burden on the entire joint portion of the metal rotating portion of the vacuum pump and the rotating portion of the cylindrical body formed of the FRP material.
For this reason, in Patent Document 1 and Patent Document 2 described above, in the cylindrical body (cylindrical rotating portion) formed of the FRP material, the load actually comes into contact with the metal rotor disposed inside the cylindrical body. No consideration is given to a sudden load change that occurs at the boundary between the applied portion and the portion that is not loaded because it is not in contact with the metal rotor.
In addition, when using FRP material for the cylindrical part of the rotor blade of the vacuum pump, in order to withstand the load caused by the centrifugal force applied in the circumferential direction, when designing the FRP material, fibers that reinforce the material properties are used. Wrap in the circumferential direction. In the cylindrical body using the FRP material formed in this way, the strength of the cylindrical body increases because the direction in which the fiber is contained (that is, the circumferential direction) bears the load applied to the cylindrical body by the fiber.
However, the direction in which the fibers are not contained (that is, the axial direction or the radial direction) bears a load applied to the cylindrical body by the resin that holds the fibers. For this reason, the strength in the direction in which no fibers are contained is almost the same as that before the fibers are added, or the strength may be reduced as a result of stress concentration.
Further, because of the anisotropy as described above, the cylindrical body formed of the FRP material may be deformed with a slight load in the axial direction or the radial direction in which no fiber is contained.

By the way, the vacuum pump in which the cylindrical rotating part manufactured by such FRP material is included may be disposed in an environment in which corrosive gas (for example, halogen gas) is exhausted. In that case, as a countermeasure against corrosion, a corrosion-resistant surface treatment is performed on the surface (part) through which the gas flows by electroless nickel plating or the like. Other examples of the corrosion-resistant surface treatment include vapor deposition methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, ion plating, and electrodeposition coating.
Thus, when the anti-corrosion surface treatment (surface anti-corrosion coating) is applied to the cylindrical rotating part, a joining part where the metallic rotating part of the vacuum pump and the cylindrical rotating part formed of the FRP material are joined, If a large load change occurs in the axial direction at the boundary portion between the non-joined portion where both are not joined, and the boundary portion between the joined portion and the non-joined portion is partially greatly deformed, that portion (joined portion) The corrosion resistant surface coating of) may be damaged due to cracking of the plating on the interface.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rotor having a structure for mitigating a load change at a joint portion with a rotating body (rotor) of a vacuum pump, and a vacuum pump that includes the rotor and has improved exhaust performance. .

The invention according to claim 1 is a rotor which is disposed in a vacuum pump and to which a cylindrical body made of a different material is joined, and has a load change mitigation structure on a surface in contact with the cylindrical body. Providing a rotor.
According to a second aspect of the present invention, the load change mitigation structure is formed on the outer diameter surface of the rotor gradually from the end surface side where the cylindrical body is joined to the rotor toward the center of the cylindrical body. The rotor according to claim 1, wherein the rotor has a gently tapered structure formed to have a small diameter.
According to a third aspect of the present invention, the load change mitigating structure is formed on the outer diameter surface of the rotor gradually from the center of the cylindrical body toward the end surface side where the cylindrical body is joined to the rotor. The rotor according to claim 1 or 2, wherein the rotor has a gently tapered structure formed so as to have a small diameter.
According to a fourth aspect of the present invention, the taper angle of the taper structure is smaller than the angle at which the cylindrical body gradually decreases in diameter from the end face side joined to the rotor toward the center of the cylindrical body. A rotor according to claim 2 is provided.
In a fifth aspect of the invention, the taper angle of the taper structure is smaller than the angle at which the cylindrical body gradually decreases in diameter from the center of the cylindrical body toward the end face side joined to the rotor. A rotor according to claim 3 is provided.
According to a sixth aspect of the present invention, in the load change mitigating structure, the end point on the end face side where the cylindrical body of the tapered structure is joined to the rotor is formed in a curved shape. The rotor according to any one of items 5 is provided.
The invention according to claim 7 is characterized in that the taper structure is formed in a position where the load change mitigation structure does not share a contact surface where the rotor and the cylindrical body come into contact. A rotor according to any one of claims 6 is provided.
In the invention according to claim 8, the load change mitigation structure is formed on the outer diameter surface of the rotor, gradually from the end surface side where the cylindrical body is joined to the rotor toward the center of the cylindrical body. The rotor according to claim 1, wherein the rotor has a gently curved structure formed to have a small diameter.
In the invention according to claim 9, the load change mitigation structure is formed on the outer diameter surface of the rotor gradually from the center of the cylindrical body toward the end surface side where the cylindrical body is joined to the rotor. The rotor according to claim 1 or 8, wherein the rotor has a gently curved structure formed so as to have a small diameter.
The invention according to claim 10 is characterized in that the load change mitigating structure is formed so that the curved structure is formed so as not to share a contact surface where the rotor and the cylindrical body contact. A rotor according to claim 9 is provided.
The invention according to claim 11 is a vacuum pump comprising a thread groove type pump part and a rotor to which a cylindrical body formed of a different material is joined, wherein the rotor is according to claims 1 to 10. A vacuum pump characterized by being the rotor according to any one of the above.

  ADVANTAGE OF THE INVENTION According to this invention, the vacuum pump which included the said rotor and which has the relaxation structure of the load change of the junction part with the rotary body of a vacuum pump, and the exhaust performance was improved can be provided.

It is the figure which showed the example of schematic structure of the turbo-molecular pump provided with the load change mitigation structure which concerns on 1st Embodiment of this invention. It is a conceptual diagram of the load change relaxation structure which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the load change mitigation structure which concerns on the modification 1 of 1st Embodiment of this invention. It is a figure for demonstrating the load change relaxation structure which concerns on the modification 2 of 1st Embodiment of this invention. It is a figure for demonstrating the load change relaxation structure which concerns on the modification 3 of 1st Embodiment of this invention. It is a figure for demonstrating the load change mitigation structure which concerns on the modification 4 of 1st Embodiment of this invention. It is a figure for demonstrating the load change mitigation structure which concerns on 2nd Embodiment of this invention. It is the figure which showed the example of schematic structure of the thread groove type pump provided with the load change mitigation structure which concerns on 3rd Embodiment of this invention. It is the figure which showed the example of schematic structure of the junction part of the rotation part and cylindrical rotation part based on the prior art of this invention.

(I) Outline of Embodiment In the embodiment of the present invention, a vacuum pump is provided with a thermal stress or the like at a joining portion where a cylindrical rotating portion formed of an FRP material or the like is joined to a metallic rotating portion such as an aluminum alloy. It has a load change relaxation structure that relaxes the load change caused by.
More specifically, a gentle taper is installed at the boundary between the rotating part and the cylindrical rotating part.

(Ii) Details of Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
In the first embodiment, as an example of a vacuum pump, a so-called composite turbo molecular pump including a turbo molecular pump part and a thread groove type pump part will be described.
Moreover, in this embodiment, it demonstrates using the turbo molecular pump 1 which arrange | positions the rotor 8 manufactured with the aluminum alloy and the cylindrical rotation part 9 manufactured with the FRP material as an example.

FIG. 1 is a diagram illustrating a schematic configuration example of a turbo molecular pump 1 including a load change relaxation structure according to the first embodiment of the present invention. FIG. 1 shows a cross section of the turbo molecular pump 1 in the axial direction.
A casing 2 that forms an exterior body of the turbo molecular pump 1 has a substantially cylindrical shape, and constitutes a casing of the turbo molecular pump 1 together with a base 3 provided at a lower portion (exhaust port 6 side) of the casing 2. doing. And inside this housing | casing, the gas transfer mechanism which is a structure which makes the turbo molecular pump 1 exhibit an exhaust function is accommodated.
This gas transfer mechanism is roughly composed of a rotating part arranged rotatably and a fixed part fixed to the casing.

An inlet 4 for introducing gas into the turbo molecular pump 1 is formed at the end of the casing 2. A flange portion 5 is formed on the end surface of the casing 2 on the intake port 4 side so as to project to the outer peripheral side.
The base 3 is formed with an exhaust port 6 for exhausting gas from the turbo molecular pump 1.

The rotating part is provided on the shaft 7 which is a rotating shaft, the rotor 8 disposed on the shaft 7, a plurality of rotating blades 8a provided on the rotor 8, and the exhaust port 6 side (screw groove type pump part). It is comprised from the cylindrical rotation part 9 grade | etc.,. The shaft 7 and the rotor 8 constitute a rotor part.
Each rotor blade 8a is composed of blades extending radially from the shaft 7 at a predetermined angle from a plane perpendicular to the axis of the shaft 7.
The cylindrical rotating unit 9 is formed of a cylindrical member having a cylindrical shape concentric with the rotation axis of the rotor 8.

A motor unit 20 for rotating the shaft 7 at a high speed is provided in the middle of the shaft 7 in the axial direction, and is included in the stator column 10.
Further, on the intake port 4 side and the exhaust port 6 side with respect to the motor portion 20 of the shaft 7, a radial magnetic bearing device 30 for rotatably supporting the shaft 7 in a radial direction (radial direction) without contact, 31 is provided at the lower end of the shaft 7 with an axial magnetic bearing device 40 for rotatably supporting the shaft 7 in an axial direction (axial direction) without contact.

A fixing portion is formed on the inner peripheral side of the housing. The fixed portion includes a plurality of fixed blades 50 provided on the intake port 4 side (turbo molecular pump portion), a thread groove spacer 60 provided on the inner peripheral surface of the casing 2, and the like.
Each fixed wing 50 is composed of a blade that is inclined by a predetermined angle from a plane perpendicular to the axis of the shaft 7 and extends from the inner peripheral surface of the housing toward the shaft 7.
The fixed wings 50 at each stage are separated and fixed by a spacer 70 having a cylindrical shape.
In the turbo molecular pump unit, the fixed blades 50 and the rotary blades 8a are alternately arranged and formed in a plurality of stages in the axial direction.

In the thread groove spacer 60, a spiral groove is formed on the surface facing the cylindrical rotating portion 9.
The thread groove spacer 60 faces the outer peripheral surface of the cylindrical rotating part 9 with a predetermined clearance, and when the cylindrical rotating part 9 rotates at a high speed, the gas compressed by the turbo molecular pump 1 is converted into the cylindrical rotating part. With the rotation of 9, it is sent to the exhaust port 6 while being guided by a thread groove (spiral groove). That is, the thread groove is a flow path for transporting gas. The screw groove spacer 60 and the cylindrical rotating portion 9 are opposed to each other with a predetermined clearance to constitute a gas transfer mechanism that transfers gas through the screw groove.
In addition, in order to reduce the force by which the gas flows backward to the inlet 4 side, the smaller the clearance, the better.
The direction of the spiral groove formed in the thread groove spacer 60 is the direction toward the exhaust port 6 when the gas is transported in the spiral groove in the rotational direction of the rotor 8.
Further, the depth of the spiral groove becomes shallower as it approaches the exhaust port 6, and the gas transported through the spiral groove is compressed as it approaches the exhaust port 6. As described above, the gas sucked from the intake port 4 is compressed by the turbo molecular pump unit, and further compressed by the thread groove type pump unit, and discharged from the exhaust port 6.

The turbo molecular pump 1 having the cylindrical rotating unit 9 manufactured using FRP, which is configured as described above, supplies various process gases such as halogen gas, fluorine gas, chlorine gas, or bromine gas to the semiconductor. When used for semiconductor manufacturing where there are many processes that act on the substrate, corrosion-resistant surface treatments such as electroless nickel plating are applied to the locations (components) where the gas comes into contact to prevent corrosion due to the gas. Applied.
The turbo molecular pump 1 according to the first embodiment of the present invention configured as described above has a load change mitigation structure at a boundary portion (joint portion) between the rotor 8 and the cylindrical rotating portion 9.

FIG. 2 is an enlarged view of a portion A (joint portion) in FIG. 1, and is a conceptual diagram of the load change mitigation structure according to the first embodiment of the present invention.
As shown by line segment αβ in FIG. 2, the turbo molecular pump 1 according to the first embodiment of the present invention has a load change mitigation structure at a boundary portion where the rotor 8 and the cylindrical rotating part 9 are joined. It has a gentle taper (line segment αβ). This taper can be formed by forming the outer diameter of the rotor 8 so that it gradually decreases from the end face side of the cylindrical rotating portion 9 toward the center.
The angle represented by θ1 in FIG. 2 is the deformation angle (reduction angle) of the cylindrical rotating portion 9 that is deformed by the thermal expansion of the rotor 8 when the taper as the load change relaxation structure is not provided (FIG. 9). Is shown.
The angle represented by θ2 in FIG. 2 indicates the taper angle of the taper provided as the load change relaxation structure.
The width indicated by t in FIG. 2 indicates the taper length of the taper as the load change mitigating structure according to the first embodiment of the present invention, that is, the projected length of the line segment αβ.
The width indicated by t0 in FIG. 2 indicates the interference width between the cylindrical rotating portion 9 and the rotor 8. That is, it is the difference between the outer diameter of the rotor 8 that is a part disposed on the inner side and the inner diameter of the cylindrical rotating part 9 that is a part disposed on the outer side.

Generally, when a component is inserted, a taper having a taper angle of about 15 degrees to 30 degrees is provided at a portion to be inserted for the purpose of facilitating insertion.
However, when the rotor 8 rotates at high speed and thermally expands, the deformation angle θ1 of the cylindrical rotating portion 9 is an angle (approximately several degrees) that is much smaller than the taper angle (15 degrees to 30 degrees). As described above, the taper angle that is normally given is not effective as a countermeasure against load change due to thermal expansion.
Therefore, the taper angle θ2 according to the load change mitigation structure of the first embodiment is much smaller than the angle at which the material, that is, the FRP itself forming the cylindrical rotating portion 9 is deformed.
That is, as shown in FIG. 2, in the first embodiment, the rotor 8 is provided with a taper having a taper angle θ <b> 2 that is an angle smaller than the angle θ <b> 1 at which the cylindrical rotating portion 9 is deformed. With this configuration, the taper functions as a relaxation mechanism that reduces the load so that the shape of the cylindrical rotating portion 9 is gently deformed.
In the first embodiment, the taper angle θ2 is set to 5 degrees or less as an example. However, it is conceivable that the angle θ1 varies depending on the thickness of the cylindrical rotating part 9, the material forming the cylindrical rotating part 9, the fiber content of the material, the winding angle of the fibers contained in the material, and the like. Therefore, it is desirable to appropriately change the value of the taper angle θ2.

  With the above-described configuration, in the turbo molecular pump 1 having the load change relaxation structure according to the first embodiment of the present invention, the deformation of the cylindrical rotating part 9 becomes smooth due to the taper as the load change relaxation structure. A sudden load change due to thermal stress at the boundary between the rotor 8 and the cylindrical rotating part 9 can be reduced. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.

Furthermore, in the load change mitigation structure according to the first embodiment of the present invention, the taper length t (projection length of the line segment αβ) provided in the rotor 8 is configured to be sufficiently long. More specifically, the contact surface where the rotor 8 and the cylindrical rotating unit 9 come into contact with each other is not shared, and the outer surface of the rotor 8 and the inner surface of the cylindrical rotating unit 9 are between the rotor 8 and the cylindrical rotating unit 9. The taper (line segment αβ) is extended to the position where the gap 90 is formed.
In addition, when the rotor 8 disposed on the inner side is subjected to thermal expansion at a high temperature and has a stronger force to spread outward, the length necessary for the taper (taper length t: line segment αβ) becomes longer. Therefore, in determining the taper length t described above, the interference width t0, that is, the condition that the part sharing the contact surface where the rotor 8 and the cylindrical rotating part 9 are in contact with each other, that is, the condition that the temperature becomes the highest is obtained. It is desirable to determine the taper length t.

With the above-described configuration, in the turbo molecular pump 1 having the load change relaxation structure according to the first embodiment of the present invention, the deformation of the cylindrical rotating part 9 becomes smooth due to the taper as the load change relaxation structure. A sudden load change due to thermal stress at the boundary between the rotor 8 and the cylindrical rotating part 9 can be reduced. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.
Further, the turbo molecular pump 1 having the load change relaxation structure according to the first embodiment of the present invention can be applied as a measure for preventing the deformation even when the turbo molecular pump 1 is significantly deformed by centrifugal force in addition to thermal expansion. .

The boundary part (contact part) between the rotor 8 and the cylindrical rotating part 9 does not necessarily need to be tapered (straight line). In other words, it is desirable to provide an R instead of a corner at the portion where the taper begins to taper in the rotor 8 (ie, the intersection of the straight line and the straight line). Therefore, the boundary portion for buffering the load is configured to have a gentle curve. Good.
Therefore, the above-described load change relaxation structure according to the first embodiment of the present invention can be modified as follows.
(Iii) Modification 1
FIG. 3 is a view for explaining a load change relaxation structure according to Modification 1 of the first embodiment of the present invention.
In FIG. 3, a rotor 81 according to the first modification of the first embodiment of the present invention and a rotor 80 having a conventional shape are shown in parallel for comparison with the rotor 81. A two-dot chain line on the rotor 81 indicates the position of the end of the conventional rotor 80.
As shown in FIG. 3, the rotor 81 according to the load change mitigation structure of the first modification includes a curved portion (curve αγ) and a tapered portion (line segment γβ) at the contact portion with the cylindrical rotating portion 9. Have.
In this way, by forming the boundary portion between the rotor 81 and the cylindrical rotating portion 9 with a gently curved portion and a tapered portion, a sudden load change due to thermal stress at the boundary between the rotor 81 and the cylindrical rotating portion 9 is achieved. Can be relaxed more gently. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.
In the first modification, the load change mitigation structure is provided by extending the joint portion of the rotor 80 having the conventional shape. However, the load change mitigation structure may be provided without extending the joint portion.

(Iv) Modification 2
FIG. 4 is a view for explaining a load change relaxation structure according to Modification 2 of the first embodiment of the present invention.
FIG. 4 shows a rotor 82 according to Modification 2 of the first embodiment of the present invention, and a two-dot chain line on the rotor 82 indicates the position of the end of the conventional rotor 80.
As shown in FIG. 4, the rotor 82 according to the load change mitigation structure of Modification 2 has a corner R (curve αβ) at the contact portion with the cylindrical rotating portion 9.
Thus, by configuring the boundary portion between the rotor 82 and the cylindrical rotating portion 9 with a gentle curve, a sudden load change due to thermal stress at the boundary between the rotor 82 and the cylindrical rotating portion 9 can be made more gentle. Can be relaxed. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.
In the second modification, the load change mitigation structure is provided by extending the joint portion of the rotor 80 having the conventional shape, but the load change mitigation structure may be provided without extending the joint portion.

(V) Modification 3
FIG. 5 is a view for explaining a load change relaxation structure according to Modification 3 of the first embodiment of the present invention.
FIG. 5 shows a rotor 83 according to Modification 3 of the first embodiment of the present invention, and a two-dot chain line on the rotor 83 indicates the position of the end of the conventional rotor 80.
As shown in FIG. 5, the rotor 83 according to the load change mitigation structure of the third modification has a lower portion (exhaust port 6 side) where the cylindrical rotating portion 9 is joined and in contact with the cylindrical rotating portion 9, as shown in FIG. It has a thin plate portion 84 formed thinner than the mouth 4 side.
Furthermore, in the rotor 83 according to the third modification of the first embodiment of the present invention, the above-described thin plate portion 84 is bent toward the inner diameter side to form the bent thin plate portion 85, so that The contact portion has a corner R (curve αβ).
In this way, by configuring the boundary portion between the rotor 83 (flexible thin plate portion 85) and the cylindrical rotating portion 9 with a gentle curve, the boundary between the rotor 83 (flexible thin plate portion 85) and the cylindrical rotating portion 9 is formed. A sudden change in load due to thermal stress can be moderated. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.
In the third modification, the joint portion of the rotor 80 having the conventional shape is extended to provide the load change mitigating structure. However, the load change mitigating structure may be provided without extending the joint portion.

Further, even when the rotor 800 and the cylindrical rotating portion 9 are conventionally joined as shown in FIG. 9B, as described above with reference to FIGS. Modified examples 1 to 3 can be applied.
(Vi) Modification 4
FIG. 6 is a view for explaining a load change relaxation structure according to Modification 4 of the first embodiment of the present invention.
FIG. 6A shows a rotor 801 according to the fourth modification of the first embodiment of the present invention, and has a taper (line segment αβ) at a contact portion with the cylindrical rotating portion 9.
FIG. 6B shows a rotor 802 according to the fourth modification of the first embodiment of the present invention. A curved portion (curve αγ) and a tapered portion (line segment) are formed at the contact portion with the cylindrical rotating portion 9. γβ).
FIG. 6C shows a rotor 803 according to the fourth modification of the first embodiment of the present invention, and has a corner R (curve αβ) at a contact portion with the cylindrical rotating portion 9.
6 (a) to 6 (c), at the boundary between the rotors 801, 802, 803 and the cylindrical rotating portion 9 according to the load change mitigation structure of the fourth modification. Sudden load changes due to thermal stress can be moderated. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.

(Vii) 2nd Embodiment FIG. 7: is a figure for demonstrating the load change mitigation structure which concerns on 2nd Embodiment of this invention.
FIG. 7A shows a rotor 8001 according to the second embodiment of the present invention, and the upper portion of the contact portion with the cylindrical rotating portion 9 also has a taper.
For reference, a conventional rotor 8000 is shown in FIG.
As shown in FIG. 7A, in the second embodiment, a load change mitigation structure is also provided on the upper part of the contact portion, and the taper angle thereof is the material, that is, the FRP that forms the cylindrical rotating portion 9. It is formed at an angle that is much smaller than the angle at which it deforms. In the second embodiment, the rotor 8001 is provided with a taper having an angle smaller than the angle at which the cylindrical rotating portion 9 is deformed. With this configuration, the taper functions as a relaxation mechanism that reduces the load so that the shape of the cylindrical rotating portion 9 is gently deformed.
In the second embodiment, the taper angle is set to 5 degrees or less as an example. However, it is desirable to appropriately change the thickness of the cylindrical rotating part 9 or the material forming the cylindrical rotating part 9, the fiber content of the material, the winding angle of the fibers contained in the material, and the like.

With the above-described configuration, in the turbo molecular pump 1 having the load change relaxation structure according to the second embodiment of the present invention, the cylindrical rotating unit 9 is deformed by the upper taper in the contact direction as the load change relaxation structure. Since it becomes smooth, a sudden load change due to thermal stress at the boundary between the rotor 8001 and the cylindrical rotating portion 9 can be reduced. As a result, it is possible to prevent damage such as cracking of the corrosion-resistant coating that occurs because it cannot cope with a sudden load change.
Moreover, the turbo-molecular pump 1 having the load change relaxation structure according to the second embodiment of the present invention can be applied as a measure for preventing the deformation even when the turbo molecular pump 1 is significantly deformed by centrifugal force in addition to thermal expansion. .
Note that the boundary portion (contact portion) between the rotor 8001 and the cylindrical rotating portion 9 is not necessarily tapered (straight line). That is, since it is desirable to provide R instead of corners at the portion where the taper starts in the rotor 8001 (the portion where the straight line intersects the straight line), the boundary portion for buffering the load is configured to have a gentle curve. Good. Moreover, you may make it the structure which provides the said taper or R-shaped gentle curve only in upper part.
Further, the load change relaxation structure according to the second embodiment of the present invention may be combined with each of the embodiments and modifications of the lower load change relaxation structure shown in the first embodiment.

(Viii) Third Embodiment The first embodiment and the first to fourth modifications and the second embodiment described above are a so-called composite type including a turbo molecular pump portion and a thread groove type pump portion as an example of a vacuum pump. However, the present invention is not limited to this, and the present invention can be applied to a thread groove type pump that does not have a turbo molecular pump portion.
FIG. 8 shows a schematic configuration diagram of a thread groove type pump 100 according to a third embodiment of the present invention. In addition, description is abbreviate | omitted about the structure similar to 1st Embodiment of this invention mentioned above, and 2nd Embodiment.
Also in the thread groove type pump 100 according to the third embodiment of the present invention shown in FIG. 8, the boundary portion (A portion) between the rotor 8 and the cylindrical rotating portion 9 is the same as in the first embodiment and the second embodiment. The described load change mitigation structure can be formed, and each modification described above can be applied.

  Further, in each embodiment and each modification of the present invention, the rotor 8 is made of an aluminum alloy and the cylindrical rotating part 9 is made of a cylindrical body formed of FRP. As long as two kinds of materials that cause a large thermal stress can be applied. For example, even if the rotor 8 is made of an aluminum alloy and the cylindrical rotating portion 9 is formed as a cylindrical body formed of titanium alloy, precipitation strengthened stainless steel, or the like, the configurations of the above-described embodiments and modifications can be applied. it can.

  The vacuum pumps according to the above-described embodiments and modifications of the present invention have been described on the assumption that the inner diameter of the cylindrical body before joining is substantially constant, but the inner diameter of the cylindrical body is the end face side joined to the rotor. When it changes in the axial direction, such as gradually becoming smaller, the taper angle may be determined accordingly.

As described above, in the vacuum pump according to each of the embodiments and modifications of the present invention described above, the deformation of the cylindrical rotating portion 9 is smoothed by the taper as the load change mitigating structure, and the rotor 8 and the cylindrical rotating portion 9 are smoothed. A sudden load change at the boundary can be mitigated.
That is, according to the configuration of each embodiment and each modification of the present invention, a rotating body is configured by disposing a lighter cylindrical rotating portion 9 made of a different material (such as FRP material) on the aluminum alloy rotor 8. Therefore, it is possible to provide a vacuum pump with improved rotational performance and improved exhaust performance as compared with the prior art.
In addition, with the configuration of each embodiment and each modification of the present invention described above, the load change mitigation function at the boundary portion between the rotor 8 and the cylindrical rotating portion 9 is improved, so that the load may change abruptly. It is possible to provide the rotor 8 that can prevent the corrosion-resistant coating from being damaged. As a result, when the rotor 8 is disposed, the corrosion resistance is improved as compared with the conventional vacuum pump, and thus a vacuum pump with improved reliability and durability can be provided.

DESCRIPTION OF SYMBOLS 1 Turbo molecular pump 2 Casing 3 Base 4 Intake port 5 Flange part 6 Exhaust port 7 Shaft 8 Rotor 8a Rotary blade 9 Cylindrical rotary part 10 Stator column 20 Motor part 30, 31 Radial direction magnetic bearing apparatus 40 Axial direction magnetic bearing apparatus 50 Fixed blade 60 Thread groove spacer 70 Spacer 80 Rotor (conventional)
81 Rotor 82 Rotor 83 Rotor 84 Thin plate portion 85 Deflection thin plate portion 90 Clearance 100 Screw groove type pump 800 Rotor (conventional)
801 Rotor 802 Rotor 803 Rotor 8000 Rotor (Conventional)
8001 Rotor

Claims (11)

A rotor disposed in a vacuum pump and joined to a cylindrical body formed of a different material,
A rotor having a load change relaxation structure on a surface in contact with the cylindrical body.   The load change mitigation structure is formed on the outer diameter surface of the rotor so that the outer diameter of the rotor gradually decreases from the end surface side where the cylindrical body is joined to the rotor toward the center of the cylindrical body. The rotor according to claim 1, wherein the rotor has a gentle taper structure.   The load change mitigation structure is formed on the outer diameter surface of the rotor such that the outer diameter of the rotor gradually decreases from the center of the cylindrical body toward an end surface side where the cylindrical body is joined to the rotor. The rotor according to claim 1, wherein the rotor has a gentle taper structure.   The taper angle of the taper structure is smaller than an angle at which the cylindrical body gradually decreases in diameter from an end surface side joined to the rotor toward the center of the cylindrical body. The rotor according to 2.   The taper angle of the taper structure is smaller than an angle at which the cylindrical body gradually decreases in diameter from the center of the cylindrical body toward an end face side joined to the rotor. The rotor according to 3.   6. The load change relaxation structure according to claim 2, wherein an end point on an end surface side where the cylindrical body of the tapered structure is joined to the rotor is formed in a curved shape. The described rotor.   7. The taper structure according to claim 2, wherein the load change mitigation structure is formed so that the contact surface where the rotor and the cylindrical body contact each other is not shared. The rotor described in 1.   The load change mitigation structure is formed on the outer diameter surface of the rotor so that the outer diameter of the rotor gradually decreases from the end surface side where the cylindrical body is joined to the rotor toward the center of the cylindrical body. The rotor according to claim 1, wherein the rotor has a gently curved structure.   The load change mitigation structure is formed on the outer diameter surface of the rotor such that the outer diameter of the rotor gradually decreases from the center of the cylindrical body toward an end surface side where the cylindrical body is joined to the rotor. The rotor according to claim 1, wherein the rotor has a gently curved structure.   10. The rotor according to claim 8, wherein the load change mitigation structure has the curved structure formed at a position where the contact surface where the rotor and the cylindrical body are in contact with each other is not shared. A vacuum pump comprising a thread groove type pump part and a rotor to which a cylindrical body formed of a different material is joined,
The said rotor is a rotor of any one of Claims 1-10, The vacuum pump characterized by the above-mentioned.

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