WO2011070856A1

WO2011070856A1 - Cylindrical fixed member of thread-groove exhaust unit and vacuum pump using same

Info

Publication number: WO2011070856A1
Application number: PCT/JP2010/068313
Authority: WO
Inventors: 透三輪田; 祐幸坂口; 好伸大立; 靖前島; 勉高阿田
Original assignee: エドワーズ株式会社
Priority date: 2009-12-11
Filing date: 2010-10-19
Publication date: 2011-06-16
Also published as: KR101773632B1; JP5758303B2; CN102667169A; CN102667169B; KR20120115204A; JPWO2011070856A1

Abstract

Disclosed is a cylindrical fixed member of a thread-groove exhaust pump unit, with which the cost of a vacuum pump can be reduced while the strength thereof against breakdown torque is maintained, in which thread grooves having complicated shapes of which width, depth, lead angle, and the like change in the rotation-axis direction of a rotating member of the thread-groove exhaust unit can be easily formed, and that is suitable for improving exhausting performance and compression performance of the entire vacuum pump by using such thread grooves. A cylindrical fixed member (thread-groove exhaust unit stator (18)) of a thread-groove exhaust unit (Ps) disposed so as to enclose the outer circumference of a rotating member (substantially the lower half of a rotor (6)) of the thread-groove exhaust unit (Ps) forms a helical thread-groove exhaust path (S) for exhausting gas between the rotating member and the cylindrical fixed member. This cylindrical fixed member includes two or more separable pieces (18A, 18B) that can be divided in the rotation-axis direction of the rotating member, and the separable pieces are joined together using a fastening means such as bolts or a joining means such as shrink fitting.

Description

Cylindrical fixing member for screw groove exhaust part and vacuum pump using this

The present invention relates to a cylindrical fixing member of a thread groove exhaust portion constituting a vacuum pump and a vacuum pump using the same, and in particular, torque generated when a rotor in the vacuum pump is broken (hereinafter referred to as “breaking torque”). While maintaining the strength of the vacuum pump, the screw groove with a complicated shape whose width, depth change, lead angle, etc. vary in the direction of the rotation axis of the rotating member of the screw groove exhaust part It can be easily manufactured on the cylindrical fixing member side of the thread groove exhaust portion, and is suitable for improving exhaust performance and compression performance of the entire vacuum pump by employing such a thread groove.

With the recent increase in wafer diameter in semiconductor manufacturing equipment, vacuum pumps used in the equipment are required to exhaust large flow gases, to achieve low ultimate pressure, and to have high exhaust performance.

As a vacuum pump satisfying such a requirement, a composite blade type vacuum pump in which a blade exhaust part and a thread groove exhaust part are combined is known (for example, see FIG. 6 of Patent Document 1 for the same type of vacuum pump).

The blade exhaust section has a structure in which rotor blades and stationary blades are alternately arranged in multiple stages. The rotor blades that rotate at high speeds give the gas molecules downward momentum and are given the downward momentum. The operation in which the gas molecules are sent to the rotor blade of the next stage by the fixed blade is repeatedly performed in multiple stages, so that the upstream gas molecules are transferred and exhausted to the downstream thread groove exhaust section.

The screw groove exhaust portion has a rotating member and a cylindrical fixing member arranged so as to surround the outer periphery of the rotating member, and is provided with a screw groove on the inner peripheral surface of the cylindrical fixing member to fix the cylindrical shape. A spiral thread groove exhaust passage is formed between the member and the rotating member. And the gas molecules transferred from the blade exhaust part as described above enter the thread groove exhaust passage, and the gas molecules are compressed and exhausted by the drag effect on the outer surface of the thread groove and the rotating member. .

However, according to the conventional thread groove exhaust portion, since the thread groove is provided on the inner peripheral surface of the cylindrical fixing member, the width, depth, lead angle, etc. vary in the direction of the rotation axis of the rotating member. It is difficult to form a thread groove having a shape, and the exhaust performance and compression performance of the entire vacuum pump cannot be improved by employing the thread groove having such a shape.

In addition, the above-described conventional cylindrical fixing member of the thread groove exhaust portion also plays a role of reducing the breaking torque by receiving the broken pieces when the breaking occurs inside the vacuum pump. For this reason, the whole cylindrical fixing member of a thread groove exhaust part cannot be produced only with a casting with low strength. In order to ensure the strength of the vacuum pump against the breaking torque, this kind of cylindrical fixing member is made of a high-strength material, for example, an expensive machined product that has been cut out from a material made by forging or extrusion / drawing. The cylindrical fixing member of the thread groove exhaust part is a factor that increases the overall cost of the vacuum pump.

JP 2002-115681 A

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to reduce the cost while maintaining the strength of the vacuum pump against the breaking torque, or to rotate the rotating shaft of the rotating member of the thread groove exhaust portion. Thread grooves with complex shapes that vary in width, depth, lead angle, etc. in the center direction can be easily produced on the cylindrical fixing member side of the thread groove exhaust section. It is an object of the present invention to provide a cylindrical fixing member of a thread groove exhaust pump part suitable for improving exhaust performance and compression performance, and a vacuum pump using the same.

In order to achieve the above object, the present invention provides a cylindrical fixing member disposed so as to surround an outer periphery of a rotating member of a screw groove exhaust portion, and a gas is interposed between the cylindrical fixing member and the rotating member. The cylindrical fixing member is divided into two or more divided pieces in the direction of the rotation axis of the rotating member.

The divided pieces of the cylindrical fixing member may be formed of different materials.

A screw groove for forming the screw groove exhaust passage is provided in the cylindrical fixing member, and the lead angle of the screw groove is different between one divided piece of the cylindrical fixing member and the other divided piece. A configuration can also be adopted.

A thread groove for forming the thread groove exhaust passage is provided in the cylindrical fixing member, and the number of threads of the thread groove is different between one divided piece of the cylindrical fixing member and the other divided piece. A configuration can also be adopted.

A thread groove for forming the thread groove exhaust passage is provided in the cylindrical fixing member, and the width of the thread groove is different between one divided piece of the cylindrical fixing member and the other divided piece. Can also be adopted.

A thread groove for forming the thread groove exhaust passage is provided in the cylindrical fixing member, and the amount of change in the depth of the thread groove in one divided piece and the other divided piece of the cylindrical fixing member is Different configurations may be employed.

A screw groove for forming the screw groove exhaust passage is provided in the cylindrical fixing member, and in one divided piece and the other divided piece of the cylindrical fixing member, from the upper end of the screw groove to the rotating member. It is also possible to adopt a configuration in which the gap between the cylindrical fixing member and the rotating member is different by changing the distance.

The above-mentioned cylindrical fixing member can employ a configuration having a groove formed on the upper surface in the direction of the rotation axis.

A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces, and the cylindrical fixing member is configured such that the thread groove of one divided piece and the thread groove of the other divided piece are continuous. You may comprise so that the thread groove alignment means connected with may be provided.

The thread groove alignment means includes an engagement pin erected on the division surface of one division piece, and an engagement hole formed in the division surface of another division piece joined to the division surface. You may comprise so that the said engagement pin may be inserted and fitted in an engagement hole.

The engagement hole is a through hole that penetrates the upper and lower end surfaces of the divided piece, and the engagement pin is inserted and fitted into one end of the through hole, while the other end of the through hole is the position of the engagement pin. You may comprise so that it may function as a confirmation window which confirms.

The thread groove alignment means includes a first step portion formed on a split surface of one split piece and a second step portion formed on a split surface of another split piece joined to the split surface. In addition, the two step portions can be configured to be joined to each other.

The thread groove alignment means includes an engaging recess formed on the split surface of one split piece and an engaging convex portion formed on the split face of another split piece joined to the split surface. The engaging convex portion may be configured to engage with the engaging concave portion.

In the present invention, it is possible to adopt a configuration in which a work handle for installing one divided piece on another divided piece is detachably attached to the one divided piece.

The lower end of the cylindrical fixing member is supported by a pump base, and the divided piece positioned at the lowermost of the two or more divided pieces is provided integrally with the pump base by processing the pump base. You may comprise as follows.

Further, the cylindrical fixing member is provided at the uppermost part of the two or more divided pieces as a product mixing preventing means for preventing the product from entering the gap between the divided pieces and the member located outside the divided pieces. The structure which equips the upper-end outer peripheral part of the division piece located with a cover part is employable.

In the present invention, a configuration in which a reinforcing member is attached to the outer peripheral portion of the divided piece may be employed.

In the present invention, as a specific configuration of the cylindrical fixing member of the screw groove exhaust portion, the cylindrical fixing member is divided into two or more divided pieces in the direction of the rotation axis of the rotating member of the screw groove exhaust portion. Therefore, the following effects (1) or (2) can be obtained.

(1) Each divided piece is formed of a different material according to the required strength. For example, a divided piece of a part requiring particularly high strength is cut out from a material made by forging or extrusion / drawing. By making the segmented piece of a part that does not require much strength and made of an inexpensive casting, the cost can be reduced while maintaining the strength of the vacuum pump.

(2) By individually threading each divided piece, the amount of change in lead angle, number of lines, width, depth, or rotating member on the inner peripheral surface of the cylindrical fixing member of the thread groove exhaust section Can be manufactured without sophisticated production facilities, and the exhaust and compression performance of the entire vacuum pump can be improved by adopting such screw grooves. It is suitable for aiming.

Sectional drawing of the vacuum pump to which the cylindrical fixing member of the thread groove exhaust part which is one Embodiment of this invention is applied. The A section enlarged view in FIG. The top view of a thread groove exhaust stator (cylindrical fixing member of a thread groove exhaust part). EE sectional drawing of FIG. Sectional drawing of other embodiment (The type from which the lead angle of a thread groove differs for every division | segmentation piece) of a thread groove exhaust part. Sectional drawing of other embodiment (The type in which the number of thread grooves differs for every division | segmentation piece) of a thread groove exhaust part. Sectional drawing of other embodiment (The type from which the width | variety of a thread groove differs for every division | segmentation piece) of a thread groove exhaust part. Sectional drawing of other embodiment (The type in which the variation | change_quantity of the depth of a thread groove differs for every division | segmentation piece) of a thread groove exhaust part. Sectional drawing of other embodiment (a type with a different gap with a rotor for every division | segmentation piece) of a thread groove exhaust part. Sectional drawing of other embodiment (type provided with the groove | channel for product deposition) of a thread groove exhaust part. Sectional drawing of other embodiment (The type provided with the thread groove alignment means by an engagement pin and an engagement hole (closed hole)) of a thread groove exhaust part. Sectional drawing of other embodiment (The type provided with the thread groove alignment means by an engagement pin and an engagement hole (through-hole)) of a thread groove exhaust part. The side view of other embodiment (The type provided with the screw groove alignment means by a level | step difference part) of the thread groove exhaust part seen from the arrow B direction of FIG. The side view of other embodiment (The type provided with the thread groove alignment means by an engagement convex part and an engagement recessed part) of the thread groove exhaust part seen from the arrow B direction of FIG. The side view of other embodiment (The type which employ | adopted the handle for work) of the thread groove exhaust part seen from the arrow B direction of FIG. Sectional drawing of the vacuum pump which employ | adopted other embodiment (The type which provided the lower part piece integrally with the pump base) of the thread groove exhaust part. Sectional drawing of other embodiment (type which employ | adopted the cover part) of the thread groove exhaust part. Sectional drawing of other embodiment (The type which employ | adopted the reinforcement member) of the thread groove exhaust part.

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

1 is a cross-sectional view of a vacuum pump to which a cylindrical fixing member of a thread groove exhaust portion according to an embodiment of the present invention is applied, FIG. 2 is an enlarged view of portion A in FIG. 1, and FIG. FIG. 4 is a cross-sectional view taken along the line EE of FIG. 3.

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

The vacuum pump P shown in FIG. 1 includes a blade exhaust part Pt that exhausts gas through the rotary blade 13 and the fixed blade 14 and a screw groove exhaust part Ps that exhausts gas through a spiral thread groove exhaust passage S. And a drive system for driving them.

<Details of exterior case>
The exterior case 1 has a bottomed cylindrical shape in which a cylindrical pump case 1A and a bottomed cylindrical pump base 1B are integrally connected with bolts in the cylinder axis direction. The upper end portion side of the pump case 1A is opened as a gas intake port 2, and a gas exhaust port 3 is provided on the side surface of the lower end portion of the pump base 1B.

The gas inlet 2 is connected to a vacuum container (not shown) that is high vacuum, such as a process chamber of a semiconductor manufacturing apparatus, by a bolt (not shown) provided on the flange 1C on the upper edge of the pump case 1A. The gas exhaust port 3 is connected so as to communicate with an auxiliary pump (not shown).

<Details of support drive system>
A cylindrical stator column 4 containing various electrical components is provided in the center of the pump case 1A, and the stator column 4 is erected in such a manner that its lower end is screwed and fixed onto the pump base 1B. is there.

A rotor shaft 5 is provided inside the stator column 4, and the rotor shaft 5 is arranged such that its upper end portion faces the gas inlet 2 and its lower end portion faces the pump base 1B. is there. Further, the upper end portion of the rotor shaft 5 is provided so as to protrude upward from the cylindrical upper end surface of the stator column 4.

A rotor 6 is provided outside the stator column 4. The rotor 6 is housed in the pump case 1 A and has a cylindrical shape surrounding the outer periphery of the stator column 4. The rotor 6 is integrated with the rotor shaft 5 described above. As an example of an integrated structure of the rotor 6 and the rotor shaft 5, in the vacuum pump P of FIG. 1, a flange 8 with a boss hole 7 is provided inside the upper end portion of the rotor 6, and a step portion 9 is provided on the outer periphery of the upper end portion of the rotor shaft 5. Is forming. Then, the upper end portion of the rotor shaft 5 above the step portion 9 is fitted into the boss hole 7 of the flange 8, and the flange 8 and the step portion 9 are fixed by screws, so that the rotor 6 and the rotor shaft 5 are integrated. ing.

The rotating body composed of the rotor shaft 5 and the rotor 6 is supported by a radial magnetic bearing 10 and an axial magnetic bearing 11 so as to be rotatable in the radial direction and the axial direction. In this state, the rotating body is rotated by a drive motor 12 with the rotor shaft 5 as an axis. Driven.

The drive motor 12 has a structure including a stator 12A and a rotor 12B, and is provided near the center of the rotor shaft 5. The stator 12 A of the drive motor 12 is installed inside the stator column 4, and the rotor 12 B of the drive motor 12 is integrally mounted on the outer peripheral surface side of the rotor shaft 5.

Two sets of radial magnetic bearings 10 are arranged one by one above and below the drive motor 12, and one set of axial magnetic bearings 11 is arranged on the lower end side of the rotor shaft 5.

The two sets of radial

magnetic bearings

10 and 10 each have a radial electromagnet target 10A attached to the outer peripheral surface of the rotor shaft 5, a plurality of radial electromagnets 10B and a radial direction displacement sensor 10C installed on the inner side surface of the stator column 4 facing this. have. The radial electromagnet target 10A is made of a laminated steel plate in which steel plates of high permeability material are laminated, and the radial electromagnet 10B attracts the rotor shaft 5 with a magnetic force in the radial direction through the radial electromagnet target 10A. The radial direction displacement sensor 10 C detects the radial displacement of the rotor shaft 5. Then, by controlling the exciting current of the radial electromagnet 10B based on the value detected by the radial direction displacement sensor 10C (the radial displacement of the rotor shaft), the rotating body composed of the rotor shaft 5 and the rotor 6 has a magnetic force at a predetermined position in the radial direction. Is supported by levitation.

The axial magnetic bearing 11 includes a disk-shaped armature disk 11A attached to the outer periphery of the lower end portion of the rotor shaft 5, an axial electromagnet 11B facing up and down across the armature disk 11A, and a position slightly away from the lower end surface of the rotor shaft 5. And an axial direction displacement sensor 11C.

The armature disk 11A is made of a material having a high magnetic permeability, and the upper and lower axial electromagnets 11B attract the armature disk 11A from the vertical direction with a magnetic force. The axial direction displacement sensor 11 C detects the axial displacement of the rotor shaft 5. Then, by controlling the exciting current of the upper and lower axial electromagnets 11B based on the detection value (axial displacement of the rotor shaft) detected by the axial direction displacement sensor 11C, the rotating body composed of the rotor shaft 5 and the rotor 6 is positioned at a predetermined position in the axial direction. Is supported by levitation by magnetic force.

<Detailed configuration of blade exhaust part Pt>
In the vacuum pump P of FIG. 1, substantially the upper half of the rotor 6 functions as a blade exhaust part Pt. Hereinafter, the blade exhaust part Pt will be described in detail.

A plurality of rotor blades 13 are integrally provided on the outer peripheral surface of the substantially upper half of the rotor 6. These rotor blades 13 are arranged radially about the rotation axis of the rotor 6 or the axis of the outer case 1 (hereinafter referred to as “pump axis”). On the other hand, a plurality of fixed wings 14 are provided on the inner peripheral surface side of the pump case 1A, and these fixed wings 14 are arranged radially around the pump axis. The rotor blades 13 and the stationary blades 14 are alternately arranged in multiple stages along the pump axis, thereby forming the blade exhaust part Pt.

Each of the rotor blades 13 is a blade-like cut product that is cut and formed integrally with the outer diameter processed portion of the rotor 6 and is inclined at an angle that is optimal for exhausting gas molecules. All the fixed blades 14 are also inclined at an angle optimal for exhaust of gas molecules.

<Exhaust operation of blade exhaust part Pt>
When the drive motor 12 is activated, the rotor shaft 5, the rotor 6, and the plurality of rotor blades 13 integrally rotate at a high speed, and the uppermost rotor blade 13 imparts a downward momentum to gas molecules incident from the gas inlet 2. . The gas molecules having the momentum in the downward direction are sent to the rotor blade 13 side of the next stage by the fixed blade 14. By applying the momentum to the gas molecules and the feeding operation repeatedly in a multistage manner, the gas molecules on the gas inlet 2 side are upstream of the screw groove exhaust part Ps (more specifically, a screw groove exhaust passage to be described later). S is exhausted so as to sequentially shift to the upstream inlet 19A).

<Detailed configuration of thread groove exhaust part Ps>
In the vacuum pump P of FIG. 1, the substantially lower half of the rotor 6 functions as the thread groove exhaust part Ps. Hereinafter, the thread groove exhaust portion Ps will be described in detail.

A substantially lower half of the rotor 6 is a portion that rotates as a rotating member of the screw groove exhaust portion Ps, and is accommodated in a cylindrical screw groove exhaust portion stator 18 that is a cylindrical fixing member of the screw groove exhaust portion Ps. Thus, as shown in FIG. 2, it is arranged so as to face the thread groove exhaust portion stator 18 with a predetermined gap G interposed therebetween. The gap G is about 0.7 mm.

The thread groove exhaust portion stator 18 (cylindrical fixing member of the thread groove exhaust portion Ps) is formed with a thread groove 19 which changes in a tapered cone shape whose depth is reduced in the downward direction at the inner peripheral portion thereof, and its lower end. The part is supported by the pump base 1B.

In the present thread groove exhaust portion Ps, a screw groove 19 is formed on the inner peripheral surface of the thread groove exhaust portion stator 18 so that the screw groove 19 and a substantially lower half outer peripheral surface of the rotor 6 opposed thereto spiral. A thread groove exhaust passage S is formed. Although not shown, by forming the screw groove on the outer peripheral surface of the substantially lower half of the rotor 6, a spiral screw groove is formed between the screw groove and the inner peripheral surface of the screw groove exhaust portion stator 18 facing the screw groove. An exhaust passage may be formed.

Further, the screw groove exhaust portion stator 18 of the main screw groove exhaust portion Ps is divided into two divided

pieces

18A and 18B in the direction of the rotation axis of the rotor 6 (rotating member of the screw groove exhaust portion Ps). The divided

pieces

18A and 18B are integrally connected by fastening means such as bolts or joining means such as shrink fitting. Due to the division of the screw groove exhaust portion stator 18, the screw groove 19 formed on the inner peripheral surface thereof is also divided in the same direction, and the divided screw groove 19 is provided in each of the divided

pieces

18A and 18B. In addition, the thread groove exhaust part stator 18 is not limited to 2 division of this example, It can divide | segment into 2 or more, such as 3 divisions and 4 divisions. Moreover, a well-known fitting structure such as a concave-convex fitting D or the like can be adopted for the connecting portion of the two divided

pieces

18A and 18B.

In the present vacuum pump P, as one embodiment of the thread groove exhaust part Ps, the two divided

pieces

18A and 18B constituting the thread groove exhaust part stator 18 are respectively formed of different materials (see FIG. 4). Specifically, the upper divided piece 18A that is close to the center of gravity of the rotor 6 and is easily affected when the rotor 6 breaks is made of a high-strength material, specifically forging or extrusion / drawing. Although it is a comparatively expensive cut product that has been cut out from the material, the lower divided piece 18B, which is less susceptible to such influence, is made as an inexpensive cast article, thereby reducing the cost while maintaining the strength of the vacuum pump. planned.

In the present vacuum pump P, the screw groove 19 is formed on the inner peripheral surface of the above-described screw groove exhaust portion stator 18, while the substantially lower half outer peripheral surface of the rotor 6 facing the screw groove 19 is formed on a smooth cylindrical surface. Thus, a spiral thread groove exhaust passage S is formed between the thread groove exhaust portion stator 18 (cylindrical fixing member) and the rotor 6 (rotating member). In the thread groove exhaust portion Ps, five thread grooves 19 are provided as shown in FIG. 3, but the number of the thread grooves 19 can be appropriately changed as necessary.

The thread groove exhaust passage S is spirally provided from the upper end to the lower end of the thread groove exhaust portion stator 18. The upstream inlet 19A of the thread groove exhaust passage S communicates with a minute gap between the lowermost rotary blade 13 and the fixed blade 14, and the downstream outlet 19B side of the thread groove exhaust passage S is connected to the gas exhaust port 3. It is configured to communicate with the side. Further, in the present thread groove exhaust portion Ps, the gas groove is transported while being compressed by a drag effect on the outer peripheral surface of the thread groove 19 and the rotor 6. It is set so as to be deepest on the side and shallowest on the downstream outlet 19B side.

<Exhaust operation of screw groove exhaust part>
As described above, when the rotor shaft 5, the rotor 6 and the plurality of rotor blades 13 are integrally rotated at a high speed by the activation of the drive motor 12, it reaches the upstream inlet 19A of the thread groove exhaust passage S by the exhaust operation of the blade exhaust portion Pt. The gas molecules enter the screw groove exhaust passage S and move toward the gas exhaust port 3 while being compressed from the transition flow to the viscous flow by the drag effect on the outer peripheral surface of the rotor 6 and the screw groove 19 and finally shown in the figure. Not exhausted through the auxiliary pump.

<Other Embodiment of Screw Groove Exhaust>
5 to 18 are explanatory views of other embodiments of the thread groove exhaust part Ps.

The thread groove exhaust part Ps in FIG. 5 divides the thread groove exhaust part stator 18 (cylindrical fixing member of the thread groove exhaust part Ps) into two divided

pieces

18A and 18B as in the embodiment of FIG. A thread groove 19 is provided in each of the divided

pieces

18A and 18B. The upper divided piece 18A and the lower divided piece 18B employ different configurations such that the lead angle θ of the screw groove 19 is 30 degrees and 15 degrees. Note that the lead angle θ of the screw groove 19 is not limited to the above example, and can be changed as needed.

The thread groove exhaust part Ps in FIG. 6 divides the thread groove exhaust part stator 18 (cylindrical fixing member of the thread groove exhaust part Ps) into two divided

pieces

18A and 18B as in the embodiment of FIG. A screw groove 19 is provided in each of the divided

pieces

18A and 18B, and the upper divided piece 18A and the lower divided piece 18B are configured such that the number of the thread grooves 19 is different.

The thread groove exhaust part Ps in FIG. 7 divides the thread groove exhaust part stator 18 (cylindrical fixing member of the thread groove exhaust part Ps) into two divided

pieces

18A and 18B as in the embodiment of FIG. The screw pieces 19 are provided in the divided

pieces

18A and 18B, and the upper divided piece 18A and the lower divided piece 18B adopt different configurations such that the width of the screw groove 19 is L1 and L2.

The thread groove exhaust part Ps in FIG. 8 divides the thread groove exhaust part stator 18 (cylindrical fixing member of the thread groove exhaust part Ps) into two divided

pieces

18A and 18B as in the embodiment of FIG. Screw

grooves

190 and 191 are provided in the divided

pieces

18A and 18B, and the amount of change in the depth of the screw groove 19 is different between the upper divided piece 18A and the lower divided piece 18B. In FIG. 8, the upper divided piece 18 A changes so that the screw groove 190 becomes shallow with the same gradient, and the lower divided piece 18 B adopts a form in which the depth of the screw groove 191 does not change (change amount = 0). However, it is not limited to this example. Although illustration is omitted, it is also possible to adopt a form in which the screw groove 191 of the lower divided piece 18B changes so as to become shallower with a gentler slope than the screw groove 190 of the upper divided piece 18A. .

The thread groove exhaust part Ps in FIG. 9 divides the thread groove exhaust part stator 18 (cylindrical fixing member of the thread groove exhaust part Ps) into two divided

pieces

18A and 18B. By changing the distance from the upper end of the screw groove 19 to the rotor 6 in the upper divided piece 18A and the lower divided piece 18B, the screw groove exhaust part stator is changed. The gap between 18 (cylindrical fixing member of the thread groove exhaust part Ps) and the rotor 6 (rotary member of the thread groove exhaust part Ps) is different, such as G1 and G2. In FIG. 9, since the product is more easily deposited on the lower divided piece 18B having a higher pressure, the gap is set to G1 <G2. The gap G1 is about 0.7 mm, and the gap G2 is about 1 mm.

The thread groove exhaust part Ps in FIG. 10 is provided with a groove 20 formed in the direction of the rotational axis on the upper surface of the thread groove exhaust part stator 18 (a cylindrical fixing member of the thread groove exhaust part Ps). Contact with the rotor blade 13 when the product is deposited on the upper surface of the thread groove exhaust portion stator 18 is caused by depositing a product generated by solidifying gas exhausted inside the pump at a high pressure portion or the like. This is to prevent it. In the example of FIG. 10, since the thread groove exhaust portion stator 18 is divided into two divided

pieces

18A and 18B, the groove 20 is provided on the upper surface of the upper divided piece 18A. Although not shown, if the thread groove exhaust portion stator 18 is divided into three or more divided pieces, the groove 20 is provided on the upper surface of the uppermost divided piece closest to the rotor blade 13. .

In the divided structure of the thread groove exhaust part stator 18 described above, it is necessary to connect the thread grooves 19 provided in the respective divided

pieces

18A and 18B so as to be continuous. This is because if the thread groove 19 is interrupted in the middle, the gas compression / exhaust operation due to the drag effect described above cannot be performed from the upstream inlet 19A to the downstream outlet 19B of the thread groove exhaust passage S. . On the other hand, since the screw groove 19 is formed on the inner peripheral surfaces of the divided

pieces

18A and 18B, and the connecting portion of the screw groove 19 is in a position that is difficult for the operator to see, the connecting operation of the screw groove 19 is difficult.

Therefore, when the split structure of the thread groove exhaust portion stator 18 described above is employed, it is preferable to employ the thread groove alignment means 21 shown in any of FIGS. Each of these screw groove alignment means 21 is means for arranging the screw groove 19 of the upper divided piece 18A and the screw groove 19 of the lower divided piece 18B so as to be continuous, and has a specific configuration thereof. Is as follows.

The thread groove alignment means 21 in FIG. 11 is formed in the engaging pin 21A formed of a taper pin standing on the dividing surface of the lower dividing piece 18B and the dividing surface of the upper dividing piece 18A joined to the dividing surface. In addition to the engagement hole 21B provided, the engagement pin 21A is inserted and fitted into the engagement hole 21B so that the screw grooves 19 of the two

split pieces

18A and 18B are aligned. . In the example of FIG. 11, the edge of the engagement hole 21B is chamfered so that the engagement pin 21A can be easily inserted into the engagement hole 21B.

Furthermore, as another embodiment, the engaging pin 21A is erected on the divided surface of the upper divided piece 18A, and the engaging hole 21B is drilled in the lower divided piece 18B joined to the divided surface. A configuration to be provided can also be adopted. A plurality of sets of the engagement pin 21A and the engagement hole 21B as described above may be provided. When two sets of them are provided, the radial positions of the upper and lower divided

pieces

18A and 18B are also determined, so that the fitting D described above can be omitted. In this case, in preparation for the case where any one of the engagement pins 21A is broken, a joining structure of

step portions

21D and 21E shown in FIG. 13 to be described later, or between the engagement convex portion 21F and the engagement concave portion 21G shown in FIG. It is desirable to employ an engagement structure.

The form of the engagement hole 21B may be a closed hole as shown in FIG. 11 described above, but may be a through-hole penetrating the upper and lower end surfaces of the upper divided piece 18A as shown in FIG. In this case, the engagement pin 21A is inserted and fitted into the lower end of the through hole, while the upper end of the through hole functions as a confirmation window 21C for confirming the position of the engagement pin 21A.

As described above, when the through hole as shown in FIG. 12 is employed as an example of the engagement hole 21B, the upper divided piece 18A and the lower division are formed by inserting and fitting the engagement pin 21A into the engagement hole 21B. When aligning the screw groove 19 with the piece 18B, the operator can confirm the position of the engagement pin 21A from the confirmation window 21C, so that the alignment operation becomes easy.

The screw groove alignment means 21 in FIG. 13 includes a first step portion 21D formed on the divided surface of the upper divided piece 18A and a first divided portion formed on the divided surface of the lower divided piece 18B joined to the divided surface. The two stepped portions 21E and the two stepped

portions

21D, 21E are at least in two places and are engaged with each other so that the screw grooves 19 of the divided

pieces

18A, 18B are aligned. It is a thing. Although illustration is omitted, the

step portions

21D and 21E may be inclined.

The thread groove alignment means 21 in FIG. 14 includes an engagement convex portion 21F formed on the divided surface of the upper divided piece 18A and an engagement formed on the divided surface of the lower divided piece 18B joined to the divided surface. The recesses 21G and the engagement protrusions 21F and the engagement recesses 21G are at least at one place and mesh with each other to engage with each other, thereby aligning the screw grooves 19 of the divided

pieces

18A and 18B. It is what was done.

In the divided structure of the thread groove exhaust portion stator 18 described above, the work of installing the upper divided piece 18A on the lower divided piece 18B is performed. In this work, the work handle 22 shown in FIG. Use improves the workability of installation.

The handle 22 has a form (eyebolt shape) in which a ring-shaped gripping portion 22B is provided on the head of the bolt 22A. A screw hole (not shown) is formed on the upper surface of the upper divided piece 18A, and the handle 22 is removably attached to the upper divided piece 18A by screwing the bolt 22A of the handle 22 into the screw hole. It is done. After the installation work as described above is completed, the main handle 22 is removed from the upper divided piece 18A and reused in the next installation work. As means for attaching the handle 22 to the upper divided piece 18A, means other than the bolt 22A may be adopted.

Each of the screw groove exhaust portions Ps described above has a screw groove exhaust portion stator 18 (a cylindrical fixing member of the screw groove exhaust portion Ps) divided into two divided

pieces

18A and 18B. 18B is supported by the pump base 1B (see FIG. 1 and the like). In this structure, the lower divided piece 18B can be provided integrally with the pump base 1B as shown in FIG. 16 by processing the pump base 1B. In addition, although illustration is abbreviate | omitted, when the thread groove exhaust part stator 18 is divided | segmented into three or more division | segmentation pieces, the division | segmentation piece located in the lowest part is provided integrally with the pump base 1B.

According to the integral configuration of the pump base 1B and the divided piece 18B as described above, the number of parts can be reduced. Further, since the pump base 1B and the lower divided piece 18B do not have a joint surface that hinders heat transfer, the entire thread groove exhaust portion stator 18 is efficiently cooled by a water cooling pipe (not shown) built in the pump base 1B. It becomes possible.

The screw groove exhaust portion Ps described above may be configured so that the upper divided piece 18A is easily bent and deformed by the breaking torque by cutting out the outer peripheral portion of the upper divided piece 18A as shown in FIG. it can. In this case, the product may enter the gap 30 formed between the divided piece 18A and the member located outside thereof (pump base 1B in the example of FIG. 17), and the gap 30 may be buried. Then, when the gap 30 is filled, the divided piece 18A is not easily deformed. The gap 30 is generated by cutting out the outer peripheral portion of the divided piece 18A.

In order to solve the problems as described above, in the thread groove exhaust portion Ps of FIG. 17, the upper outer peripheral portion of the upper divided piece 18 A as a product mixing preventing means for preventing the product from entering the gap 30. A lid 40 is provided. Although illustration is omitted, when the thread groove exhaust portion stator 18 is divided into three or more divided pieces, at least the outer peripheral portion of the divided piece located at the uppermost part is cut out and bent and deformed. The lid 40 is provided on the outer periphery of the upper end of the split piece located at the uppermost part while being configured to be easy.

By the way, if the strength of the lid portion 40 is too high, the effect of bending deformation of the upper divided piece 18A is impaired. Therefore, the lid portion 40 is preferably configured to have a low strength by reducing its thickness as much as possible.

The specific configuration of the lid 40 is different from the upper divided piece 18A, for example, as shown in FIG. 17, in which a thin plate is attached and fixed to the upper end surface of the upper divided piece 18A with a fixing member 40A such as a screw. It may be a part. Further, as described above, when the outer peripheral portion of the upper divided piece 18A is cut out, a portion that should become the lid portion 40 is left as shown in FIG. 18, so that the lid portion 40 is separated from the upper divided piece 18A. You may comprise as an integral component. FIG. 17 shows an example in which the lid 40 is employed in a structure in which the lower divided piece 18B is integrated with the pump base 1B. However, the lower divided piece 18B is integrated with the pump base 1B. It is possible to adopt even a structural example that is not (see FIG. 1 etc.).

By the way, the upper split piece 18A is easily bent and deformed by the gap 30 as described above, and at the same time, is easily broken by a relatively weak force. If it breaks easily with a weak force, the effect of bending deformation of the upper divided piece 18A cannot be sufficiently exhibited. For this reason, in the thread groove exhaust portion Ps of FIG. 18, a high-strength member such as CFRP is attached as a reinforcing member 50 to the outer peripheral portion of the upper divided piece 18 A, specifically, the portion where the gap 30 is formed. FIG. 18 shows an example in which the reinforcing member 50 is adopted in the structural example in which the lower divided piece 18B is integrated with the pump base 1B. However, the lower divided piece 18B is integrated with the pump base 1B. An unstructured structure (see FIG. 1 etc.) can also be adopted.

In the screw groove exhaust part Ps of FIGS. 5 to 18 described above, the divided

pieces

18A and 18B may be formed of different materials as shown in FIG. Further, a screw groove having a more complicated shape can be adopted by appropriately combining the

screw grooves

19, 190 and 191 having complicated shapes as shown in FIGS.

In all the embodiments described above, as a specific configuration of the thread groove exhaust portion stator 18 (fixing member for the thread groove exhaust portion Ps), the thread groove exhaust portion stator 18 is provided with the rotor 6 (rotation of the thread groove exhaust portion Ps). Since the structure in which the member is divided into two or more

divided pieces

18A and 18B in the direction of the rotation axis is employed, the following effects (1) or (2) can be obtained.

(2) By performing the thread groove processing for each divided piece individually, the lead angle θ, the number of threads, the width L1, L2, the amount of change in depth, or the rotor 6 on the inner peripheral surface of the thread groove exhaust portion stator 18 Can be manufactured without the need for advanced production equipment, and improved exhaust performance and compression performance of the vacuum pump as a whole. Can be achieved.

DESCRIPTION OF SYMBOLS 1 Exterior case

1A Pump case

1B Pump base 1C Flange 2 Gas inlet 3 Gas exhaust 4 Stator column 5 Rotor shaft 6 Rotor 7 Boss hole 8 Flange 9 Step part 10 Radial magnetic bearing 10A Radial electromagnet target 10B Radial electromagnet 10C Radial direction displacement Sensor 11 Axial magnetic bearing

11A Armature disk

11B Axial electromagnet 11C Axial direction displacement sensor 12 Drive motor 12A Stator 12B Rotor 13 Rotor 14 Fixed vane 18 Thread groove

exhaust part stator

18A,

18B Split pieces

19, 190, 191 Thread groove 19A Thread groove exhaust passage upstream inlet 19B Thread groove exhaust passage downstream outlet 20 Product accumulation groove 21 Thread groove alignment means 21A Engagement pin

21B Engagement hole

21C Confirmation window 21D First step portion 21E Second step Part 2 1F Engagement convex part 21G Engagement concave part 22 Handle 22A Bolt 22B Gripping part 30 Gap 40 between the split piece and the member positioned outside the lid part 50 Reinforcing member D Fitting G, G1, G2 Rotor and screw groove exhaust part stator L1, L2 Thread groove groove width P Vacuum pump Pt Blade exhaust part Ps Thread groove exhaust part S Thread groove exhaust passage θ Thread groove lead angle

Claims

A cylindrical fixing member arranged so as to surround the outer periphery of the rotating member of the thread groove exhaust part,
A spiral thread groove exhaust passage for exhausting gas is provided between the cylindrical fixing member and the rotating member, and the cylindrical fixing member has two or more in the direction of the rotation axis of the rotating member. A cylindrical fixing member for a thread groove exhaust portion, which is divided into a plurality of divided pieces.
The cylindrical fixing member of the thread groove exhaust portion according to claim 1, wherein the divided pieces of the cylindrical fixing member are formed of different materials.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The cylindrical fixing member for a screw groove exhaust portion according to claim 1, wherein the lead angle of the screw groove is different between the one divided piece and the other divided piece.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The cylindrical fixing member of the thread groove exhaust portion according to claim 1, wherein the number of thread grooves is different between the one divided piece and the other divided piece.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The cylindrical fixing member for a screw groove exhaust portion according to claim 1, wherein the width of the screw groove is different between the one divided piece and the other divided piece.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The cylindrical fixing member of the thread groove exhaust portion according to claim 1, wherein the amount of change in the depth of the thread groove is different between the one divided piece and the other divided piece.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The gap between the cylindrical fixing member and the rotating member is different between the one divided piece and the other divided piece by changing the distance from the upper end of the screw groove to the rotating member. The cylindrical fixing member of the thread groove exhaust part.
The cylindrical fixing member for a thread groove exhaust portion according to claim 1, wherein the cylindrical fixing member has a groove formed on the upper surface thereof in the direction of the rotation axis.
A thread groove for forming the thread groove exhaust passage is provided in each of the divided pieces,
The cylindrical fixing member is
The cylindrical fixing member for a screw groove exhaust portion according to claim 1, further comprising screw groove alignment means for connecting the screw groove of one divided piece and the screw groove of another divided piece so as to be continuous. .
The thread groove alignment means is
The engaging pin is erected on the dividing surface of one divided piece and the engaging hole is formed in the dividing surface of another divided piece joined to the divided surface. The cylindrical fixing member of the thread groove exhaust portion according to claim 9, wherein is inserted and fitted.
The engagement hole is a through hole that penetrates the upper and lower end surfaces of the divided piece, and the engagement pin is inserted and fitted into one end of the through hole, while the other end of the through hole is the position of the engagement pin. The cylindrical fixing member for the thread groove exhaust portion according to claim 10, wherein the cylindrical fixing member functions as a confirmation window for confirming the above.
The thread groove alignment means is
The first stepped portion formed on the dividing surface of one divided piece and the second stepped portion formed on the divided surface of the other divided piece joined to the divided surface, and the two stepped portions are mutually connected. The cylindrical fixing member of the thread groove exhaust portion according to claim 9, wherein the cylindrical fixing member is joined.
The thread groove alignment means is
The engaging concave portion formed on the dividing surface of one divided piece and the engaging convex portion formed on the dividing surface of the other divided piece joined to the dividing surface, and the engaging convex portion is the engaging portion The cylindrical fixing member of the thread groove exhaust portion according to claim 9, wherein the cylindrical fixing member is engaged with the recess.
The cylindrical fixing of the screw groove exhaust portion according to claim 1, wherein a work handle for installing one divided piece on the other divided piece is detachably attached to the one divided piece. Element.
The cylindrical fixing member has a lower end supported by a pump base,
The tube of the thread groove exhaust portion according to claim 1, wherein a split piece positioned at a lowermost part of the two or more split pieces is provided integrally with the pump base by processing the pump base. Shape fixing member.
The cylindrical fixing member is
As a product mixing prevention means for preventing a product from entering a gap between the above-mentioned divided piece and a member located outside the divided piece, an upper end outer peripheral portion of the divided piece located at the top of the two or more divided pieces The cylindrical fixing member for a thread groove exhaust portion according to claim 1, further comprising a lid portion.
The cylindrical fixing member for the thread groove exhaust portion according to claim 1, wherein a reinforcing member is attached to an outer peripheral portion of the divided piece.
A vacuum pump using the cylindrical fixing member of the thread groove exhaust portion according to any one of claims 1 to 17.