JPWO2012165105A1 - Vacuum pump - Google Patents

Abstract

It is an object of the present invention to provide a vacuum pump that can be assembled without applying vacuum grease and can perform an appropriate face seal. Between the casing and the base, there is provided a tolerance and heat deformation absorbing structure in which an O-ring configured to be crushed by a crushing margin having an appropriate repulsive force is disposed. In the vacuum pump, when using a fixed blade having a large height dimension tolerance (for example, a fixed blade by press molding) or a full-stage blade type with a large number of rotor blades and fixed blades, If the crushing distance of the O-ring arranged in the above-described tolerance and thermal deformation absorption structure exceeds the allowable strain (strain) in one stage, the number of O-rings to be arranged is multi-staged, and the O-ring per stage. The crushing margin of the ring is configured to a crushing margin capable of maintaining a sealing performance suitable for the O-ring. In this case, a ring-shaped spacer is provided between the O-rings arranged in multiple stages and the O-rings to prevent the O-rings from shifting.

Description

  The present invention relates to a vacuum pump, and more particularly, to a vacuum pump including a seal structure using an O-ring in a seal structure that closely contacts a casing and a base.

Among various types of vacuum pumps, there are a full-stage blade (multi-stage blade) type turbo molecular pump and a thread groove type pump that are frequently used to realize a high vacuum environment.
Such a vacuum pump has a casing which forms the exterior body provided with the inlet port and the exhaust port, and the structure which makes the said vacuum pump exhibit an exhaust function is accommodated in the inside of the said casing. The structure that exhibits the exhaust function is roughly divided into a rotating part (rotor part) that is rotatably supported 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 rotor blades (moving blades) provided radially are arranged in multiple stages on the rotating body. . In the fixed portion, stator blades (stator blades) are arranged in multiple stages alternately with respect to the rotor blades.
In addition, a motor for rotating the rotating shaft at high speed is provided, and when the rotating shaft rotates at high speed by the action of this motor, gas is sucked from the intake port due to the interaction between the rotor blade and the stator blade, and from the exhaust port. It is supposed to be discharged.
Among vacuum devices that are kept in a vacuum by performing exhaust treatment using such a vacuum pump, measurement chambers and surface analyzers for electron microscopes that require a higher vacuum are generally equipped with a multistage blade type. A turbomolecular pump is used.

FIG. 5 is a cross-sectional view showing a conventional multi-stage blade type turbo molecular pump 100.
As shown in FIG. 5, the multistage blade type turbo molecular pump has a structure in which the fixed blades 10 and the fixed blade spacers 20 are alternately stacked in the axial direction from the intake port 4 side to the exhaust port 6 side. . When the fixed blades 10 and the fixed blade spacers 20 are alternately stacked in this manner, the dimensional tolerances of the fixed blades 10 and the fixed blade spacers 20 are similarly increased, resulting in the design dimensions of the turbo molecular pump. It can deviate significantly from an appropriate value (ie, a predetermined tolerance for dimensional tolerances).
Here, the tolerance is a + (plus) or-(minus) dimensional difference from a reference dimension that occurs when manufacturing each part constituting the turbo molecular pump. It often occurs on the order of tens of micrometers.
When the fixed blade 10 and the fixed blade spacer 20 are assembled (stacked) when the turbo molecular pump 100 shown in FIG. 5 is manufactured, tolerances generated in the fixed blade 10 and the fixed blade spacer 20 are also stacked. As a result, a large dimensional variation (a product variation) occurs.
Conventionally, in order to absorb the above-described accumulation of dimensional tolerances (stacking variation), a predetermined number of fixed wings 10 and fixed wing spacers 20 are stacked between a casing 2 and a base 3 after being stacked a predetermined number. In this structure, a gap A is provided, and after being stacked, the bolt 70 is fastened, and further, a vacuum seal (cylindrical sealing method) is performed using an O-ring 80 to absorb the accumulation of dimensional tolerance.
Here, the gap A is not uniform for each vacuum pump because the dimensional tolerances of the fixed blade 10 and the fixed blade spacer 20 accumulate. Therefore, by forming a cylindrical seal structure using the O-ring 80 as shown in FIG. 5, the crushing distance of the O-ring 80 (ie, O The numerical value relating to how much the ring is compressed) can be set irrespective of the gap A. In addition, the fixed wings made of aluminum and the fixed wing spacers and the casing made of stainless steel are thermally expanded by heat generated during the operation of the pump. However, due to the difference in thermal expansion between aluminum and stainless steel, the amount of deformation varies. . When the heat of the pump rises, the coefficient of thermal expansion of aluminum is larger than that of stainless steel, so that the gap A is widened.
On the other hand, in this structure in which the casing 2 is covered from above after the O-ring 80 is disposed in the O-ring groove, the casing 2 and the O-ring 80 come into contact with each other when the casing 2 is covered. Force is applied in the shear direction. That is, the casing 2 was disposed while contacting as if the O-ring 80 was scraped off.
For this reason, conventionally, it has been necessary to apply vacuum grease (lubricating oil) to the surface of the O-ring 80 in order to prevent the O-ring 80 from being damaged by the force applied in the shear direction.

Here, the risk of vacuum contamination that may occur when vacuum grease is applied to the surface of the O-ring 80 will be described. When vacuum grease is applied to the O-ring 80, the vacuum grease applied to the O-ring 80 is mixed into the exhaust path through a minute gap formed between the casing 2 and the base 3, for example. The risk of vacuum contamination that enters the vacuum space via the path increases. Thus, when vacuum grease is applied to the O-ring 80, there is a risk of affecting the vacuum state in the device disposed in the vacuum pump.
Therefore, it was necessary to vacuum seal the O-ring 80 without applying vacuum grease.

Special table 2002-516959 JP 2004-076662 A

In Patent Document 1, a seal ring (21 ') is arranged to vacuum-tightly connect the flange (21) and the chassis (5).
Patent Document 2 describes a technique in which an outer stator (4) is fixed to an outer casing (7) with a bolt via a heat insulating material (8a).

  As described in Patent Document 1, in the face sealing method in which an O-ring groove is formed and sealed, pressure in the shearing direction is not applied to the O-ring, so that a vacuum pump can be assembled without using vacuum grease. .

However, the face seal technique described in Patent Document 1 has the following problems.
(1) It becomes necessary to strictly manage the height dimension tolerance of the fixed wing or the fixed wing spacer, and as a result, the manufacturing cost increases.
(2) When using fixed blades with large height tolerances (for example, fixed blades by press molding) or full-stage blades (multistage blades) type turbo molecular pumps with many stages, there is a variation in product stacking. Since it becomes large, it was necessary to provide a structure that appropriately absorbs the variation in the product.
More specifically, when the stacked dimension is larger than the reference dimension, there is a gap between the casing and the base, and the amount of squashed O-ring becomes small. As a result, the repulsive force appropriate for the O-ring is lost, the surface sealing ability is reduced, and the possibility of leakage increases.
On the other hand, when the stacked dimension is smaller than the reference dimension, the surface seal by the O-ring works properly, but even if the casing and the base are in close contact, the fixed blade and the fixed blade spacer may not be in close contact. there were. As a result, the rotor blades and the stationary blade spacer cannot be sufficiently cooled, and appropriate heat transfer (heat radiation) to the heat radiated from the rotor blades is not performed, and the possibility of overheating of the vacuum pump is increased.
When the temperature of the pump rises, the amount of thermal expansion of the fixed blade and fixed blade spacer made of aluminum is larger than that of the casing made of stainless steel, so there is a gap between the casing and the base, and the O-ring crushing amount is small. Become. As a result, the repulsive force appropriate for the O-ring is lost, the surface sealing ability is reduced, and the possibility of leakage increases.
(3) When the crushing amount of the O-ring increases, the permanent distortion of the O-ring increases, the sealing ability decreases, and the risk of leaks increases.

  Moreover, the heat insulating material (8a) in Patent Document 2 is for thermally insulating the outer stator (4) and the inner stator (5), and is an O-ring for vacuum-sealing the casing and the base. Function is different. Moreover, the heat insulating material (8a) alone does not fulfill the sealing function.

  Then, an object of this invention is to provide the vacuum pump which can be assembled in a vacuum pump, without using vacuum grease. It is another object of the present invention to provide a vacuum pump capable of realizing an appropriate face seal structure even when the height dimensional tolerance of the fixed wing or the fixed wing spacer is designed to be large.

According to the first aspect of the present invention, an exterior upper body in which an intake port is formed, an exterior lower body in which an exhaust port is formed, a fixed portion disposed on an inner side surface of the exterior upper body, and fixed to the fixed portion A plurality of fixed wings arranged from the inner peripheral surface of the exterior upper body toward the center of the exterior upper body, the rotary shaft included in the exterior upper body and rotatably supported, A plurality of rotor blades arranged radially around the rotation shaft, a motor for rotating the rotation shaft, the outer upper body, the outer lower body, a plurality of seal members, and each seal member are disposed between the seal members. A spacer for fixing a seal member, and a tolerance and thermal deformation absorbing structure configured by a fastener for fastening the exterior upper body and the exterior lower body. The seal member and the spacer are alternately stacked in the fastening direction of the fastener. When the fastener fastens the exterior upper body and the exterior lower body, by applying a pressing force in the fastening direction to the laminated seal member and the spacer, the fixed portion or the fixed wing A vacuum pump characterized in that it absorbs the variation in the product buildup.
According to a second aspect of the present invention, the number of the plurality of seal members disposed in the tolerance and thermal deformation absorbing structure is such that the seal performance of the seal member is reduced by crushing each of the plurality of seal members disposed. The vacuum pump according to claim 1, wherein the vacuum pump is determined so as to be maintained.
According to a third aspect of the present invention, the exterior lower body is provided with a plurality of gaps for accommodating the seal members and the spacers, and the seal members and the spacers are disposed in the gaps to form the tolerance and thermal deformation absorbing structure. A vacuum pump according to claim 1 or claim 2 is provided.

  According to the present invention, there is provided a vacuum pump that can be assembled without using vacuum grease and that can realize an appropriate face seal structure even if the height dimensional tolerance of the fixed blade or fixed blade spacer is large. can do.

It is the figure which showed the example of schematic structure of the turbo-molecular pump provided with the tolerance and thermal deformation absorption structure which concern on embodiment of this invention. It is an enlarged view of the tolerance and heat-deformation absorption structure which concern on embodiment of this invention. It is the conceptual diagram which showed each state corresponding to various load patterns of the O-ring and the spacer in the tolerance and thermal deformation absorption structure which concern on embodiment of this invention. It is an enlarged view of the tolerance and thermal deformation absorption structure which concern on the modification of embodiment of this invention. It is the figure which showed the example of schematic structure of the conventional turbo-molecular pump.

(I) Outline of Embodiment In the vacuum pump according to the embodiment of the present invention, a tolerance and a thermal deformation absorbing structure for absorbing the tolerance of the fixed blade or the fixed blade spacer are provided between the casing and the base.
More specifically, in this tolerance and thermal deformation absorbing structure, an O-ring for face-sealing the casing and the base is disposed, and the O-ring has a crushing margin with an appropriate repulsive force (for example, 10 to 30%). An appropriate repulsive force will be described later.
This tolerance and thermal deformation absorbing structure can absorb the tolerance of the fixed wing or the fixed wing spacer and can provide an appropriate surface seal between the casing and the base.
In the vacuum pump, a fixed blade having a large height dimensional tolerance (for example, a fixed blade formed by press molding) or a full-stage blade type with a large number of fixed blades or fixed blade spacers is used. If the crushing distance of the O-ring arranged in the above-described tolerance and thermal deformation absorbing structure exceeds the allowable strain (strain) in one-stage O-ring, the O-ring to be arranged is multi-staged. The crushing margin of the O-ring per step is configured as a crushing margin (for example, 10 to 30%) that can maintain the sealing performance appropriate for the O-ring. In this case, a plate-like spacer is provided between the O-rings arranged in multiple stages and the O-rings to prevent the O-rings from shifting.

(Ii) Details of Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS.
In the present embodiment, as an example of a vacuum pump, a description will be given using an all-stage blade (multistage blade) type turbo molecular pump having a large number of stages of rotating blades and fixed blades.
The present embodiment may be applied to a so-called composite turbo molecular pump including a turbo molecular pump unit and a thread groove type pump unit.

FIG. 1 is a diagram illustrating a schematic configuration example of a turbo molecular pump 1 having a tolerance and thermal deformation absorption structure according to an embodiment of the present invention. 1 shows a cross-sectional view 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 divided into a rotating part that is rotatably supported and a fixed part that is 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 portion includes a shaft 7 that is a rotating shaft, a rotor 8 disposed on the shaft 7, a plurality of rotating blades 9 provided on the rotor 8, and the like. The shaft 7 and the rotor 8 constitute a rotor part.
Each rotor blade 9 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.

A motor portion 60 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 50.
Further, on the intake port 4 side and the exhaust port 6 side with respect to the motor portion 60 of the shaft 7, radial magnetic bearing devices 30, 31 for axially supporting the shaft 7 in a radial direction (radial direction) without contact. An axial magnetic bearing device 40 for supporting the shaft 7 in the axial direction (axial direction) in a non-contact manner is provided at the lower end of the shaft 7.

A fixing portion is formed on the inner peripheral side of the housing. This fixed portion is provided with a plurality of fixed blades 10 provided in multiple stages from the intake port 4 side to the exhaust port 6 side, and each fixed blade 10 has a predetermined angle from a plane perpendicular to the axis of the shaft 7. It is composed of a blade that is inclined only and extends from the inner peripheral surface of the housing toward the shaft 7.
The fixed wings 10 at each stage are fixed by being separated from each other by a fixed wing spacer 20 having a cylindrical shape.
In the multistage blade-type turbo molecular pump unit according to the present embodiment, the fixed blades 10 and the rotary blades 9 are alternately arranged and formed in a plurality of stages in the axial direction.
With the configuration described above, the turbo molecular pump 1 compresses the gas sucked from the intake port 4 and discharges it from the exhaust port 6, thereby evacuating the vacuum chamber (not shown) disposed in the turbo molecular pump 1. Processing is to be performed.

(Tolerance and heat deformation absorption structure)
FIG. 2 is an enlarged view of the tolerance and thermal deformation absorbing structure according to the embodiment of the present invention, indicated by B portion in FIG.
As shown in FIG. 2, the tolerance and thermal deformation absorption structure of the turbo molecular pump 1 according to the embodiment of the present invention includes a casing 2, a base 3, O-rings 81, 82, 83, spacers 90, 91. And a bolt 70.
As an example, the tolerance and thermal deformation absorbing structure according to the present embodiment includes an O-ring (81, 82, 83) having a diameter of 5.33 mm and a plate-like spacer (90, 91) having a thickness of 6 mm. I have.
In the turbo molecular pump 1 according to the embodiment of the present invention, a gap (gap) is provided between the casing 2 and the base 3, and O-rings (81, 82, 83) are arranged in the gap.
Further, a spacer 90 and a spacer 91 are provided between the O-ring 81 and the O-ring 82 and between the O-ring 82 and the O-ring 83, respectively. This is because the rounded O-rings (81, 82, 83) are arranged and sealed to each other, and there is a possibility that the intended sealing function cannot be fully achieved due to unstable contact between parts. Because there is a structure that sandwiches plate-shaped spacers (90, 91) between them, the structure that contacts the O-ring and the spacer instead of the O-rings stabilizes the contact between parts and improves the sealing function. This is to make it happen.

Next, how the tolerance and thermal deformation absorption structure included in the turbo-molecular pump 1 according to the embodiment of the present invention absorbs the variation of the fixed blade 10 or the fixed blade spacer 20 and thermal deformation, and the casing. How to seal 2 and the base 3 will be described.
3 (a) to 3 (d) show the stacked fixed blades 10 of the O-rings (81, 82, 83) and the spacers (90, 91) in the tolerance and thermal deformation absorbing structure according to the embodiment of the present invention. FIG. 4 is a conceptual diagram showing each state at various loads received from the fixed blade spacer 20.
In FIG. 3, as an example, the O-rings 81 and 82 and the spacers 90 and 91 are extracted and described.

FIG. 3A shows a state in which no load is applied to the O-rings (81, 82, 83) in the tolerance and thermal deformation absorbing structure according to the embodiment of the present invention. More specifically, before the casing 2 is covered in the assembly stage of the turbo molecular pump 1 according to the embodiment of the present invention, the O-rings (81, 82, 83) and the spacers (90, 91) are not loaded. The state under load is shown. In the present embodiment, the weights of the main bodies of the O-rings (81, 82, 83) and the main bodies of the spacers (90, 91) are not calculated as “loads” for convenience.
3 (b) to 3 (d) show a state in which the O-rings (81, 82, 83) are loaded and crushed in the tolerance and thermal deformation absorbing structure according to the embodiment of the present invention.
More specifically, FIG. 3B shows a state of the O-rings (81, 82, 83) having the design dimensions in the turbo molecular pump 1 according to the embodiment of the present invention. At this time, the collapse rate of the O-rings (81, 82, 83) is about 30%.

FIG. 3C shows the tolerance and heat in the case where the height dimension due to the stacking of the fixed blade 10 and the fixed blade spacer 20 is minimized when the turbo molecular pump 1 according to the embodiment of the present invention is assembled. The state of the O-ring (81, 82, 83) disposed in the deformation absorbing structure is shown.
In this case, the crushing rate of the O-rings (81, 82, 83) after the casing 2 and the base 3 are fastened with the bolt 70 becomes the maximum (ε: max). That is, since a large difference on the minus side occurs in the height dimension of the fixed blade 10 and the fixed blade spacer 20 stacked, the dimension C in FIG. 2 becomes smaller than the reference dimension, and as a result, the O-ring (81, The collapse rate of 82 and 83) is increased.

  FIG. 3D shows the tolerance and heat in the case where the height dimension due to the stacking of the fixed blade 10 and the fixed blade spacer 20 is maximized when the turbo molecular pump 1 according to the embodiment of the present invention is assembled. The state of the O-ring (81, 82, 83) disposed in the deformation absorbing structure is shown. In this case, the crushing rate of the O-rings (81, 82, 83) after the casing 2 and the base 3 are fastened with the bolt 70 is minimized (ε: min). That is, since a large plus difference is generated in the tolerance of stacking the fixed blade 10 and the fixed blade spacer 20, the dimension C in FIG. 2 becomes larger than the reference dimension, and as a result, the O-ring (81, 82, 83) the crushing rate is small.

As described below, the O-rings (81, 82, 83) provided in the tolerance and thermal deformation absorption structure according to the embodiment of the present invention have an appropriate repulsive force (crushable allowance, (Allowable ratio).
More specifically, the maximum collapse rate and the minimum collapse rate of each O-ring (81, 82, 83) arranged in the tolerance and thermal deformation absorption structure according to the embodiment of the present invention are calculated by the following formula (A ) Calculate based on (B).

(A)... Maximum collapse rate of O-ring (ε: max) = {D− (H−dH)} / D
(B)... Minimum collapse rate of O-ring (ε: min) = {D− (H + dH)} / D
However, at this time, “dH” represents “the height fluctuation amount of the O-ring” and can be obtained by the following calculation formula (C).

(C)... DH = (product variation + thermal deformation amount + component deformation amount) / N

As shown in the calculation formula (C) described above, in the present embodiment, the height fluctuation amount (dH) of the O-ring (81, 82, 83) can be obtained only by the variation in the product of the fixed blade 10 or the fixed blade spacer 20. In addition, since it is calculated in consideration of the amount of thermal deformation of the fixed wing 10 and the fixed wing spacer 20, the tolerance and the thermal deformation absorbing structure according to the embodiment of the present invention can be calculated by using each component (the fixed wing 10 and the fixed wing spacer 20. Etc.) can be adapted to deformation due to thermal expansion.

In the embodiment of the present invention, the limit crush rate (ε1) of the O-ring, which is a limit value at which the O-ring cracks or excessively deforms, is 40% as an example, and the crush rate required for the O-ring seal (ε2) ) Is 20% as an example. Further, the maximum collapse rate of the O-ring (ε: max), the limit collapse rate of the O-ring (ε1), the minimum collapse rate of the O-ring (ε: min) and the O-ring seal The following relational expressions (D) and (E) are established between the required crushing ratio (ε2).

(D) ... O-ring limit crush rate (ε1) <O-ring maximum crush rate (ε: max)
(E) ... Collapse rate required for O-ring seal (ε2) <Minimum collapse rate of O-ring (ε: min)

Note that “D”, “H”, and “N” used in the above equations are the following numerical values.
D: Diameter of the O-ring (81, 82, 83) in an unloaded state H: Design dimension of the collapse amount in a state where the height of the O-ring (81, 82, 83) is not varied N: O-ring (81, 82, 83) Number of stacked

In the tolerance and thermal deformation absorption structure according to the embodiment of the present invention, the appropriate values (18 to 42%) of the arranged O-rings satisfying the above-described formulas (calculation formulas, relational formulas), and the O-rings. As a result of considering both the tolerance in which the gas is disposed and the gap size secured in the turbo molecular pump 1 due to the thermal deformation absorbing structure, it is derived that three O-rings are suitable. It was.
In the tolerance and thermal deformation absorbing structure according to the present embodiment, an appropriate number of O-rings determined as described above are arranged in the gap between the casing 2 and the base 3 via spacers, and then A plurality of O-rings (81, 82, 83) to be arranged can be configured to exhibit an appropriate repulsive force by fastening the gaps with bolts 70.
As a result, the tolerance and thermal deformation absorbing structure in which the O-ring (81, 82, 83) is disposed can appropriately absorb the variation in the product of the fixed blade 10 or the fixed blade spacer 20 (tolerance absorption function). The difference in thermal expansion can be absorbed and the casing 2 and the base 3 can be properly sealed (surface sealing function).

In the present embodiment, as an example, the collapse amount with respect to the diameter of the O-ring is expressed as a percentage, but the present invention is not limited to this. For example, various representations (calculation methods) such as using an O-ring occupation amount with respect to the O-ring groove or using a contraction (compression) amount of the volume of the O-ring can be adopted.
In this embodiment, the number of O-rings arranged is three (three stages), but the number (number of stages) is not limited to this. Various combinations (one, two, four, etc.) may be considered depending on the clearance size for the tolerance and heat deformation absorbing structure and the type (performance) of the O-ring to be arranged.
That is, when the fixed wing 10 uses a fixed wing having a large height dimensional tolerance (for example, a fixed wing formed by press molding), or is a full-stage wing type having a large number of stages of the fixed wing 10 and the fixed wing spacer 20. When the crushing distance of the O-ring disposed in the above-described tolerance and thermal deformation absorbing structure exceeds the allowable strain (strain) in a single-stage O-ring, the O-ring to be disposed is multi-staged. Thus, the crushing margin of the O-ring per stage is configured to be less than the allowable strain. A spacer is provided between the O-rings arranged in multiple stages and the O-rings to prevent the O-rings from shifting.

Further, with the above-described configuration, in the turbo molecular pump 1 having the tolerance and thermal deformation absorption structure according to the embodiment of the present invention, each component (the fixed blade 10 and the fixed blade spacer 20) has a small tolerance, and the fixed Even when the assembled dimensions of the blades 10 and the fixed blade spacers 20 are small, each component (the fixed blades 10 and the fixed blade spacers 20) has large tolerances. Even in the case where the dimension after the assembly of the stacked spacers 20 is large, the casing 2 and the base 3 are fastened with bolts 70 through the tolerance and heat deformation absorbing structure. The blade 10 and the fixed blade spacer 20 can be brought into close contact with each other without a gap.
Therefore, the heat generated by the rotor blade 9 generated when the turbo molecular pump 1 operates can be efficiently radiated, and the risk of overheating of the turbo molecular pump 1 can be reduced.

(Modification of tolerance and thermal deformation absorbing structure)
Next, a modification of the embodiment of the present invention will be described with reference to FIG.
FIG. 4 is an enlarged view of a modified example of the tolerance and thermal deformation absorbing structure (B portion of FIG. 1) according to the above-described embodiment of the present invention.
As shown in FIG. 4, the tolerance and thermal deformation absorbing structure according to the present modification are the same as the embodiment shown in FIG. 2, the casing 2, the base 3, the O-rings 81, 82, 83, and the spacers. 90 and 91 and a bolt 70.
Here, in the tolerance and thermal deformation absorption structure according to this modification, a gap (gap) is provided in the base 3, and O-rings (81, 82, 83) are arranged in the gap, and the O-ring is arranged. A spacer 90 and a spacer 91 are provided between 81 and the O-ring 82 and between the O-ring 82 and the O-ring 83, respectively. Although not shown, after the O-ring is crushed, a gap due to tolerance and a thermal deformation absorbing structure may be formed between the casing 2 and the base 3 as in the above-described embodiment of the present invention.
The above-described relational expressions and the calculation formulas (A) to (E) are the same as those in the embodiment described with reference to FIGS. 2 and 3.

As described above, in the turbo molecular pump 1 according to the embodiment and the modification of the present invention, the casing 2 and the base 3 are face-sealed by the tolerance and the thermal deformation absorption structure provided between the casing 2 and the base 3. Therefore, the O-rings (81, 82, 83) disposed in the tolerance and thermal deformation absorbing structure are only loaded from above when assembling the turbo molecular pump 1, and force is applied in the shear direction to the side surface. Since it is not added, it is not necessary to apply vacuum grease for avoiding breakage due to the force in the shear direction.
As a result, the turbo molecular pump 1 according to the embodiment of the present invention can assemble a vacuum pump without using vacuum grease, thereby avoiding the risk of vacuum contamination that can be expected when using vacuum grease. Is possible.
As described above, according to the tolerance and thermal deformation absorbing structure according to the embodiment of the present invention, the turbo molecular pump designed with a large dimensional tolerance of the fixed blade 10 and the fixed blade spacer 20, Appropriate tolerances and thermal deformation absorbing structures and face seal structures can be realized even for all-stage blade type turbo molecular pumps having a large number of stages.

In the embodiment of the present invention, as described above, three O-rings having a diameter of 5.33 mm (three stages) and two spacers having a thickness of 6 mm (two stages) are arranged. However, the present invention is not limited to this, and it varies depending on the diameter of the O-ring to be arranged and the size of the gap (gap) provided between the casing 2 and the base 3 (depth in the axial direction, width in the radial direction). It is possible to change the design.
Alternatively, if appropriate stability can be maintained in the tolerance and thermal deformation absorption structure, a configuration in which only a plurality of O-rings are provided without providing a spacer between the O-rings and the O-rings is also possible. Is possible.

Thus, according to the embodiment of the present invention, it is possible to provide a vacuum pump that can be assembled without using vacuum grease, and thus it is possible to avoid vacuum contamination due to vacuum grease.
In addition, a vacuum pump is provided that can realize an appropriate tolerance, a thermal deformation absorbing structure, and a face seal structure even when the height dimensional tolerance of the fixed blade or the fixed blade spacer is increased. It becomes possible.

DESCRIPTION OF SYMBOLS 1 Turbo molecular pump 2 Casing 3 Base 4 Intake port 5 Flange part 6 Exhaust port 7 Shaft 8 Rotor 9 Rotor blade 10 Fixed blade 20 Fixed blade spacer 30, 31 Radial direction magnetic bearing device 40 Axial direction magnetic bearing device 50 Stator column 60 Motor Part 70 Bolt 80, 81, 82, 83 O-ring 90, 91 Spacer 100 Turbo molecular pump

Claims (3)

An exterior upper body with an air inlet,
An exterior lower body in which an exhaust port is formed;
A fixing portion disposed on an inner side surface of the outer body;
A plurality of fixed wings fixed to the fixing portion and disposed from the inner peripheral surface of the exterior body to the center of the exterior body;
A rotating shaft enclosed in the outer body and rotatably supported;
A plurality of rotary blades arranged radially around the rotary shaft;
A motor for rotating the rotating shaft;
The exterior upper body, the exterior lower body, a plurality of seal members, a spacer that is disposed between the seal members and fixes the seal member, and a fastener that fastens the exterior upper body and the exterior lower body. Tolerance and thermal deformation absorption structure,
The tolerance and thermal deformation absorbing structure includes a plurality of the sealing members and the spacer that are alternately stacked in a fastening direction of the fastener, and the fastener is fastened to fasten the exterior upper body and the exterior lower body. A vacuum pump characterized in that a variation in the product of the fixed portion or the fixed blade is absorbed by applying a pressing force in the fastening direction to the seal member and the spacer.   The number of the plurality of seal members disposed in the tolerance and thermal deformation absorbing structure is determined so that the seal performance of the seal member can be maintained by collapsing each of the plurality of seal members disposed. The vacuum pump according to claim 1, wherein   A space for accommodating a plurality of the seal members and the spacer is provided in the exterior lower body, and the tolerance and the thermal deformation absorbing structure are formed by disposing the seal member and the spacer in the space. The vacuum pump according to claim 1 or 2.

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