Vacuum pump and connecting type thread groove spacer

Abstract

Provided is a vacuum pump that can prevent the exhaust performance of a vacuum pump from decreasing even when a connecting thread groove spacer is fastened with a fixing bolt. The connecting thread groove spacer of an embodiment of the present invention has a structure that connects a Sigbain pump unit and a thread groove pump unit. When the connecting thread groove spacer is fastened, a countersunk hole is preliminarily provided in the exhaust flow path, and the spacer is fastened with a base with the help of a fixing bolt. By so providing, the head of the fixing bolt does not protrude into the exhaust flow path, and the head of the fixing bolt does not become a resistance to the exhaust gas. In this way, the exhaust performance of the vacuum pump can be suppressed from decreasing.

Description

Technical Field

[0001] The present invention relates to a vacuum pump and a connecting thread groove spacer. More specifically, the present invention relates to a vacuum pump and a connecting thread groove spacer that suppress the reduction of exhaust performance caused by a fixing bolt when the connecting thread groove spacer is fastened and connected in a vacuum pump having a thread groove pump part (cylindrical thread part) and a sigebain pump part. Background Art

[0002] The Sigbain type molecular pump with a Sigbain type structure used in the past has a rotating circular plate (rotating disc), a fixed circular plate arranged with a gap (gap) in the axial direction with the rotating circular plate, and a spiral groove (also called a spiral groove or a vortex groove) flow path is engraved on the surface facing the gap of at least one of the rotating circular plate or the fixed circular plate. In addition, it is a vacuum pump that applies a motion in the tangential direction of the rotating circular plate (that is, the tangential direction of the rotation direction of the rotating circular plate) to the gas molecules diffused into the spiral groove flow path by means of the rotating circular plate, thereby exhausting the gas from the air intake port to the exhaust port with a dominant directionality by means of the spiral groove.

[0003] In order to use such a sigebain molecular pump or a vacuum pump having a sigebain molecular pump unit in industry, the compression ratio is insufficient if the rotating disk and the fixed disk are in a single stage, so they are multi-staged. If the number of stages is increased to meet the required compression performance, the size of the pump itself becomes larger accordingly.

[0004] In addition, in the case of multi-stage, it is necessary to make the rotating disk into a half shape. In this way, it is necessary to lengthen the outer cylinder (shell) of the pump to a length covering the sigebain part (sigebain pump part), and in this case, the size of the pump itself also becomes larger.

[0005] In addition, in a thread groove type molecular pump having a thread groove pump type structure, especially a vacuum pump of high temperature specification, in order to improve the compression performance at the thread portion (thread groove portion), the length of the thread groove portion (thread length) is lengthened or it is manufactured as a parallel path type with more than two flow paths.

[0006] However, the manufacturing cost increases because the thread length increases, the peripheral structure (shell, etc.) of the exhaust structure increases, and because the parallel path increases the number of complicated parts.

[0007] Figure 8 This is a diagram for explaining a conventional single-path screw-type vacuum pump.

[0008] For example, in the conventional vacuum pump 1001 having a single-path thread groove spacer 2001 with one flow path, if the compression performance is to be improved, the axial length of the thread groove portion needs to be lengthened. If the axial length of the thread groove portion is lengthened in this way, the base 3 needs to be correspondingly enlarged, so the manufacturing cost increases.

[0009] Patent document 1: Japanese Patent Application Publication No. 2017-106365.

[0010] Patent document 1 discloses a connecting type thread groove spacer that maintains the exhaust performance of a thread groove pump unit and realizes miniaturization, and a vacuum pump equipped with the connecting type thread groove spacer. That is, the connecting type thread groove spacer described has a structure that connects a Sigbaan pump unit and a thread groove pump unit, and the structure of the thread groove pump unit as an exhaust element is a structure in which a Sigbaan-type structure is installed on a cylindrical thread, and the structure is provided to connect the parts in the installation portion. That is, the intersection of the flow path of the Sigbaan unit and the cylindrical thread (thread groove pump unit) is connected in a manner that is approximately right angled when viewed from the axial direction of the vacuum pump, and the flow paths of the Sigbaan unit and the thread groove pump unit are connected. With the help of this structure, the compression flow path length of the thread groove pump unit is extended radially due to the connected Sigbaan unit.

[0011] However, the above-mentioned Patent Document 1 does not describe, for example, how to fix the connecting type thread groove spacer to the base portion. In other words, the method for fastening the connecting type thread groove spacer is unclear.

[0012] However, when assembling the vacuum pump, the assembly work is easy if the vacuum pump is gradually stacked from the bottom (exhaust port side). That is, when the connecting type thread groove spacer is fastened to the base, for example, if the exhaust flow path portion of the connecting type thread groove spacer can be fastened by a fixing bolt, the work can be performed from the upper side of the vacuum pump, so there is no need to reverse the vacuum pump during the work, and the work efficiency is improved.

[0013] On the other hand, if a fixing bolt is provided in the exhaust flow path portion of the connecting type thread groove spacer, the head of the fixing bolt becomes a resistance to the exhaust gas, which may affect the performance of the vacuum pump. Summary of the invention

[0014] Therefore, an object of the present invention is to provide a vacuum pump and a connecting type thread groove spacer which are provided with a counterbore in an exhaust flow path portion of the connecting type thread groove spacer to fasten and connect with a fixing bolt without deteriorating the exhaust performance.

[0015] The present invention recorded in Technical Solution 1 provides a vacuum pump, comprising an outer body, a fixing part, a sigbain pump part, and a threaded groove pump part, wherein the outer body is formed with an air intake port or an air exhaust port, and the fixing part is built into the outer body. The vacuum pump is characterized in that it is provided with a connecting type threaded groove spacer, and the connecting type threaded groove spacer has a structure for connecting the sigbain pump part and the threaded groove pump part, and a countersunk hole is provided on the exhaust flow path of the connecting type threaded groove spacer, and the connecting type threaded groove spacer and the outer body or the fixing part are fastened and connected by means of a fixing bolt arranged in the countersunk hole.

[0016] The present invention described in Technical Solution 2 provides a vacuum pump described in Technical Solution 1, characterized in that a heating mechanism for heating the thread groove pump portion is provided on the aforementioned outer casing or the aforementioned fixing part, and the aforementioned fixing bolt is configured to contact the high-temperature portion of the aforementioned outer casing or the aforementioned fixing part heated by the aforementioned heating mechanism.

[0017] The present invention described in claim 3 provides the vacuum pump described in claim 2, characterized in that the fixing bolt is made of a material having a higher thermal conductivity than iron-based bolts.

[0018] The present invention recorded in Technical Solution 4 provides a connecting type thread groove spacer, which is used for a vacuum pump having an outer body, a fixing part, a sigbain pump part, and a thread groove pump part. The outer body is formed with an air intake port or an air exhaust port, and the fixing part is built into the outer body. The connecting type thread groove spacer is characterized in that the connecting type thread groove spacer has a structure for connecting the sigbain pump part and the thread groove pump part. At the connecting type thread groove spacer, a countersunk hole for fixing bolts is provided on the exhaust flow path surface, and the fixing bolts are used to fasten the spacer to the outer body or the fixing part.

[0019] Effects of the Invention

[0020] According to the present invention, even when the coupling type thread groove spacer is fastened and coupled by the fixing bolt, it is possible to prevent the exhaust performance of the vacuum pump from being deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a diagram showing a schematic configuration example of a vacuum pump according to an embodiment of the present invention.

[0022] Figure 2 It is a figure for demonstrating the connection type thread groove spacer which concerns on embodiment of this invention.

[0023] Figure 3 It is a figure for demonstrating the connection type thread groove spacer which concerns on embodiment of this invention.

[0024] Figure 4This is a diagram showing a location where the fixing bolt according to the present embodiment is arranged in the exhaust flow path portion of the connecting type thread groove spacer.

[0025] Figure 5 It is a perspective view showing a portion where the fixing bolt according to the present embodiment is arranged in the exhaust flow path portion of the connecting type thread groove spacer.

[0026] Figure 6 This is a diagram showing a location where a fixing bolt according to an embodiment of the present invention is arranged in an exhaust flow path portion of a connecting type thread groove spacer.

[0027] Figure 7 It is a diagram for explaining a coupling type thread groove spacer provided with a cap according to a first modification of the embodiment of the present invention.

[0028] Figure 8 It is a diagram for explaining the prior art (single-path thread type). DETAILED DESCRIPTION

[0029] (i) Overview of Embodiments

[0030] The connecting type thread groove spacer of the embodiment of the present invention has a structure for connecting the Sigbain pump part and the thread groove pump part. A countersunk hole is pre-set in the exhaust flow path part (exhaust flow path surface) of the connecting type thread groove spacer, and it is fastened and connected with the base part by means of a fixing bolt, for example, thereby preventing the head of the fixing bolt from protruding and becoming resistance and reducing the exhaust performance of the vacuum pump.

[0031] In addition, a countersunk hole is provided in the exhaust flow path portion of the connecting thread groove spacer, and fastened with a fixing bolt, so when assembling the vacuum pump, the installation work can be gradually stacked from the top of the vacuum pump (intake port side), thereby improving the working efficiency.

[0032] (ii) Details of implementation methods

[0033] A vacuum pump according to an embodiment of the present invention comprises a sigbain pump unit and a thread groove pump unit, wherein the sigbain pump unit is engraved (arranged) with a spiral groove having peaks and valleys on at least one side of a fixed circular plate or a rotating circular plate, and furthermore, the thread groove pump unit is provided with a thread groove spacer, wherein the thread groove spacer forms a spiral groove on the opposite surface facing the rotating cylinder, separating a predetermined gap and facing the outer peripheral surface of the rotating cylinder, and the thread groove pump unit is a gas transfer mechanism as follows: the rotating cylinder rotates at a high speed, whereby the gas is guided by the thread groove (spiral groove) as the rotating cylinder rotates, and is simultaneously sent to the exhaust port side.

[0034] The Sigbain pump part and the thread groove pump part are connected by a connecting thread groove spacer. When the connecting thread groove spacer is fastened to the base, for example, a countersunk hole is provided in advance to prevent the head of the fixing bolt from protruding into the exhaust flow path and becoming an obstacle to exhaust after fastening with the fixing bolt.

[0035] Below, refer to Figures 1 to 7 , suitable embodiments of the present invention are described in detail.

[0036] (ii-1) Structure of vacuum pump

[0037] Figure 1 1 is a diagram showing a schematic configuration example of a vacuum pump 1 according to a first embodiment of the present invention, and is a cross-sectional view of the vacuum pump 1 in the axial direction.

[0038] In the embodiments of the present invention, for convenience, the diameter direction of the rotor blade is referred to as the "diameter (diameter / radius) direction" and the direction perpendicular to the diameter direction of the rotor blade is referred to as the "axial direction (or axial direction)".

[0039] The shell (outer cylinder) 2 forming the outer body of the vacuum pump 1 is roughly cylindrical in shape, and together with the base 3 provided at the lower part (exhaust port 6 side) of the shell 2, constitutes the housing of the vacuum pump 1. In addition, a gas transfer mechanism is housed inside the housing as a structure that enables the vacuum pump 1 to perform the exhaust function.

[0040] In the present embodiment, the gas transfer mechanism is roughly divided into a rotating portion (rotor portion / sigbain portion) supported rotatably and a fixed portion (thread groove pump portion) fixed to a casing.

[0041] Although not shown in the drawings, a control device for controlling the operation of the vacuum pump 1 is connected to the outside of the outer casing of the vacuum pump 1 via a dedicated line.

[0042] An air inlet 4 for introducing gas into the vacuum pump 1 is formed at the end of the housing 2. Furthermore, a flange 5 is formed on the end surface of the housing 2 on the air inlet 4 side so as to protrude toward the outer peripheral side.

[0043] Furthermore, the base portion 3 is formed with an exhaust port 6 for exhausting gas from the vacuum pump 1 .

[0044] The rotating part includes a shaft 7 as a rotating shaft, a rotor 8 disposed on the shaft 7, a plurality of rotary blades 9 provided on the rotor 8, and a rotor cylindrical part 10 provided on the exhaust port 6 side (thread groove pump part). The shaft 7 and the rotor 8 constitute a rotor part.

[0045] Each rotor blade 9 is composed of a disk-shaped disc member extending radially perpendicularly to the axis of the shaft 7. In the present embodiment, the lowest stage (exhaust port 6 side) of the rotor blade 9 is a disc, and a structure is provided to compress the sigebain portion.

[0046] The rotor cylindrical portion 10 is formed of a cylindrical member having a cylindrical shape concentric with the rotation axis of the rotor 8 .

[0047] A motor portion for rotating the shaft 7 at high speed is provided in the middle portion of the shaft 7 in the axial direction and is built into the stator column 80 .

[0048] Furthermore, in the stator column 80, radial magnetic bearing devices for supporting the shaft 7 in a radial direction (radial direction) without contact are provided on the air inlet 4 side and the air outlet 6 side relative to the motor portion of the shaft 7. In addition, at the lower end of the shaft 7, an axial magnetic bearing device for supporting the shaft 7 in an axial direction (axial direction) without contact is provided.

[0049] A fixing portion (fixing component) is formed on the inner circumference of the housing (shell 2). The fixing portion is composed of fixing wings 50 and the like, and is composed of a sheet extending from the inner circumference of the shell 2 toward the shaft 7 at a predetermined angle from a plane perpendicular to the axis of the shaft 7. The fixing wings 50 are fixed to each other by spacers (fixing components) in a cylindrical shape.

[0050] The rotary blades 9 and the fixed blades 50 are alternately arranged and formed in multiple stages in the axial direction. However, in order to satisfy the discharge performance required for the vacuum pump, any number of rotor parts and stator parts can be provided as needed.

[0051] Furthermore, in the present embodiment, a thread groove pump unit having a connecting thread groove spacer 20 is disposed at a position closer to the exhaust port 6 than the above-mentioned sigebain pump unit.

[0052] In the connection type thread groove spacer 20 , a thread groove (helical groove) is formed on a surface facing the rotor cylindrical portion 10 similarly to a conventional thread groove spacer.

[0053] The facing surface side (i.e., the inner peripheral surface parallel to the axis of the vacuum pump 1) of the connecting type thread groove spacer 20 faces the outer peripheral surface of the rotor cylinder 10 with a predetermined gap, and when the rotor cylinder 10 rotates at a high speed, the gas compressed by the vacuum pump 1 is guided by the thread groove as the rotor cylinder 10 rotates and is sent to the exhaust port 6. That is, the thread groove is a flow path for conveying gas.

[0054] Thus, the surface of the coupling type thread groove spacer 20 facing the rotor cylindrical portion 10 faces the rotor cylindrical portion 10 with a predetermined gap therebetween, thereby constituting a gas transfer mechanism for transferring gas via the thread grooves formed on the inner peripheral surface of the coupling type thread groove spacer 20 in the axial direction.

[0055] In order to reduce the force of the gas flowing back toward the air inlet 4, the gap is preferably as small as possible.

[0056] Furthermore, the direction of the spiral groove formed in the coupling type spiral groove spacer 20 is the direction toward the exhaust port 6 when the gas is conveyed in the spiral groove in the rotation direction of the rotor 8 .

[0057] Furthermore, 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 .

[0058] According to the above structure, in the vacuum pump 1, the gas sucked from the suction port 4 is compressed by the sigbain part, further compressed by the threaded groove pump part, and discharged from the exhaust port 6, so the vacuum pump 1 can perform vacuum exhaust processing in the vacuum chamber (not shown in the figure) provided in the vacuum pump 1.

[0059] The connecting type thread groove spacer 20 has a counterbore 800 for fixing bolts 700 in advance in the exhaust flow path of the gas, and is fastened to the base 3 by the fixing bolts 700. The counterbore 800 is provided in advance to prevent the head 710 of the fixing bolt 700 from protruding and causing exhaust resistance of the gas in the exhaust flow path.

[0060] In addition, the fixing and coupling type thread groove spacer 20 may be the shell 2 or another component disposed inside the base 3 in addition to the base 3 .

[0061] At the base 3, a cartridge heater 900 for heating the inside is fixed by bolts 910. The inside of the vacuum pump 1 is heated to prevent the exhaust gas from being precipitated in the vacuum pump 1. The cartridge heater 900 may be a single one or a plurality of cartridge heaters may be arranged at a predetermined phase. In addition, a belt-shaped belt heater may be used instead of the cartridge heater 900.

[0062] (ii-2) Structure of the connecting type thread groove spacer

[0063] The above-mentioned coupling type thread groove spacer 20 will be described in detail.

[0064] Figure 2 It is a figure for demonstrating the connection type thread groove spacer 20 which concerns on embodiment of this invention.

[0065] like Figure 2As shown, the coupling type thread groove spacer 20 of the present embodiment includes a thread groove spacer axis perpendicular portion 201 and a thread groove spacer axis parallel portion 202 .

[0066] The thread groove spacer shaft vertical portion 201 is formed substantially vertically (horizontally) relative to the axial direction of the vacuum pump 1. The surface of the thread groove spacer shaft vertical portion 201 on the air inlet 4 side faces (confronts) the rotating blade 9 of the sigbarn part with a predetermined gap, and is engraved with a spiral groove having a mountain portion and a valley portion. On the other hand, the surface of the thread groove spacer shaft vertical portion 201 on the side opposite to the air inlet 4 side is arranged on the base 3 side.

[0067] The thread groove spacer axis parallel portion 202 is configured to be substantially parallel to the axial direction of the vacuum pump 1. The thread groove spacer axis parallel portion 202 has a thread groove formed on its inner peripheral surface that faces the rotor cylindrical portion 10 with a predetermined gap therebetween.

[0068] (ii-3) Basic structure of the connection part

[0069] Figure 3 It is a figure for demonstrating the connection type thread groove spacer 20 of this embodiment.

[0070] As described above, a spiral groove having a vertical peak 300 and a vertical valley 400 is engraved in the thread groove spacer shaft vertical portion 201 , while a thread groove having a parallel peak 500 and a parallel valley 600 is formed in the thread groove spacer shaft parallel portion 202 .

[0071] Here, the connecting type thread groove spacer 20 of this embodiment is as follows Figure 3 As shown, the thread groove spacer 20 is a connected type thread groove spacer 20 in which the thread groove spacer axis perpendicular portion 201 and the thread groove spacer axis parallel portion 202 are integrally formed, for example, by manufacturing by casting.

[0072] By providing the thread groove spacer shaft perpendicular portion 201 and the thread groove spacer shaft parallel portion 202 as an integrated structure, the labor and manufacturing cost required for fastening can be reduced compared to a structure in which they are fastened as separate parts.

[0073] As described above, in the vacuum pump 1 of this embodiment, by providing the connecting type thread groove spacer 20, the gas is compressed in the flow path perpendicular to the axial direction by means of the thread groove spacer axis perpendicular portion 201 and the rotor blade 9 (sigbarn portion). Then, the gas is further compressed in the flow path parallel to the axial direction by means of the thread groove spacer axis parallel portion 202 and the rotor cylindrical portion 10 (thread groove pump portion).

[0074] Thus, in the vacuum pump 1 of the present embodiment, the connecting type thread groove spacer 20 plays the role of connecting the gas flow path from the perpendicular direction to the parallel direction with respect to the axial direction, so that the length (n) of the shell 2 in the axial direction (see Figure 2 ), the length of the base 3 in the axial direction (m) (refer to Figure 2 ) becomes longer (i.e., suppressing the height of the vacuum pump 1 as a whole from becoming higher), the flow path for compressing the gas becomes longer. In addition, the flow path connected from the vertical direction to the parallel direction is a flow path in the reverse shape of the letter "L" when observed in the axial cross section.

[0075] In addition, in the present embodiment, the thread groove spacer axis vertical portion 201 and the thread groove spacer axis parallel portion 202 of the connecting thread groove spacer 20 are integrally formed, but the present invention is not limited thereto. For example, even if the thread groove spacer axis vertical portion 201 and the thread groove spacer axis parallel portion 202 are formed of separate parts, as long as they are formed in an inverted L shape from the vertical direction to the parallel direction with respect to the axial direction as described above, there is no problem in terms of performance.

[0076] (ii-4) Fastening method of fastening type screw groove spacer according to the present embodiment

[0077] Figure 4 This is a diagram showing a location where the fixing bolt 700 of the present embodiment is arranged in the exhaust flow path portion of the connecting type thread groove spacer 20 . Figure 5 It is a perspective view showing a location where the fixing bolt 700 of the present embodiment is arranged in the exhaust flow path portion of the connecting type thread groove spacer 20 .

[0078] As shown in these drawings, the fixing bolts 700 are arranged in a predetermined number (plurality) at equal intervals in the exhaust flow path portion of the connecting type thread groove spacer 20 .

[0079] The exhaust flow path portion of the connecting type thread groove spacer 20 is preliminarily provided with a counterbore 800 for receiving the fixing bolt 700 . After the fixing bolt 700 is fastened, the head 710 of the fixing bolt 700 does not protrude toward the exhaust flow path portion.

[0080] The fixing bolt 700 is disposed close to the cartridge heater 900 and receives heat from the cartridge heater 900 so as not to become lower than the ambient temperature.

[0081] When assembling the vacuum pump 1, it is easy to assemble from the base 3 to the upper side (toward the air inlet 4). Therefore, the fixing bolt 700 is arranged in the exhaust flow path of the connecting type thread groove spacer 20. That is, if the fixing bolt 700 is arranged in the exhaust flow path of the connecting type thread groove spacer 20, the assembly work can be easily performed from the upper side.

[0082] Furthermore, in order to fix the connecting thread groove spacer 20, a flange may be provided at a location unrelated to the exhaust flow path of the connecting thread groove spacer 20 to fasten the connecting thread groove spacer 20, but this will increase the number of parts or the size of the vacuum pump 1 itself, so it is not adopted in this embodiment.

[0083] Figure 6 This figure shows a state in which, when the fixing bolt 700 is arranged in the exhaust flow path portion of the connecting thread groove spacer 20 in this embodiment, a counterbore 800 corresponding to the size of the fixing bolt 700 is pre-provided in the exhaust flow path portion of the connecting thread groove spacer 20, and the head 710 of the fixing bolt 700 does not protrude into the exhaust flow path portion.

[0084] The head 710 of the fixing bolt 700 and the installation surface X of the exhaust flow path portion of the connecting type thread groove spacer 20 are as flat as possible. That is, the installation surface X cannot be a completely flat surface because the exhaust flow path portion of the connecting type thread groove spacer 20 is a structure that is inclined toward the inner diameter side. Therefore, the sinking depth of the countersunk hole 800 is appropriately adjusted to set the installation surface X close to a flat surface so that the head 710 of the fixing bolt 700 and the groove generated by the sinking do not become exhaust resistance.

[0085] By configuring in this way, it is possible to prevent the head 710 of the fixing bolt 700 from becoming an exhaust resistance and affecting the exhaust performance of the vacuum pump.

[0086] In the present embodiment, it is desirable that the fixing bolt 700 be arranged at a position that does not affect the exhaust performance of the vacuum pump 1 as much as possible.

[0087] Exhaust gas passing through the exhaust flow path of the coupling thread groove spacer 20 has the property of flowing along the inner wall surface. Therefore, the fixing bolt 700 is preferably arranged near the outer wall surface, that is, radially outward (away from the rotation center).

[0088] By arranging the fixing bolt 700 at such a position, it is possible to further prevent the exhaust performance of the vacuum pump 1 from being affected.

[0089] The fixing bolt 700 is disposed adjacent to a high temperature component (the cartridge heater 900 or a component heated by the cartridge heater 900) (see Figure 4 ). If the temperature of the fixed bolt 700 (head 710) disposed in the exhaust flow path of the connecting thread groove spacer 20 is low, the exhaust gas solidifies and precipitates in this part. In order to prevent this, it is desirable that the fixed bolt 700 itself is also heated to a high temperature.

[0090] Therefore, the fixing bolt 700 is disposed at a location where it is likely to receive heat from the heat source (cartridge heater 900 ).

[0091] Furthermore, since the fixing bolt 700 is not in full contact with the connecting thread groove spacer 20, the temperature of the fixing bolt 700 may be lower than that of other parts. Therefore, it is desirable to use a material with the best possible thermal conductivity.

[0092] Specific materials include stainless steel and aluminum. The material of the fixing bolt 700 is not limited to commercially available materials, and may be selected from metals with excellent thermal conductivity. Specifically, a metal with excellent thermal conductivity compared to iron-based bolts, such as aluminum bolts, is preferred.

[0093] The fixing bolt 700 is preferably a bolt with a hexagonal hole in consideration of operability from the top. The diameter of the head 710 is preferably smaller than 8.5 mm, such as 7.0 mm. By setting the bolt with a smaller diameter of the head 710, the hole diameter of the sinking part can be made smaller, and the movement resistance of the gas molecules of the exhaust gas in the sinking part can be reduced.

[0094] Furthermore, by making the diameter of the counterbore 800 smaller than a predetermined diameter for the fixing bolt 700, the clearance with the diameter of the head 710 of the fixing bolt 700 is reduced. This can also reduce the movement resistance of gas molecules of the exhaust gas in the sunken portion.

[0095] (ii-5) Modification of the method for fastening and fastening the fastening type screw groove spacer of the present embodiment

[0096] Next, refer to Figure 7 , describing a variation of the present embodiment.

[0097] Figure 7 This is a diagram showing a modified example of the present embodiment in which the upper portion of the installed fixing bolt 700 is covered with a cap 550 .

[0098] As described above, when a hexagonal bolt is used as the fixing bolt 700, the hexagonal hole is exposed in the exhaust flow path of the connecting thread groove spacer 20. It is considered that gas molecules of the exhaust gas are retained in the hexagonal hole, which becomes a resistance to exhaust.

[0099] Therefore, the head 710 of the fixing bolt 700 is covered by the cap 550. In order to arrange the cap 550, the counterbore 800 is slightly enlarged in advance.

[0100] The cap 550 is preferably made of a metal having excellent thermal conductivity in order to prevent the temperature from being lower than the ambient temperature.

[0101] The cap 550 can prevent gas molecules of the exhaust gas from accumulating at the position where the fixing bolt 700 is arranged. In addition, since the smoothness of the exhaust flow path of the connecting screw groove spacer 20 can be ensured, the fixing bolt 700 can be prevented from becoming a resistance to exhaust gas.

[0102] Furthermore, the embodiment and each embodiment of the present invention may be combined as necessary.

[0103] Description of Reference Numerals

[0104] 1 Vacuum pump

[0105] 2 Shell

[0106] 3 Base

[0107] 4 Intake port

[0108] 5 Flange

[0109] 6 Exhaust ports

[0110] 7-axis

[0111] 8 rotors

[0112] 9 Rotary Wing

[0113] 10 Rotor cylinder

[0114] 20 Connecting Type Thread Groove Spacer

[0115] 50Fixed wing

[0116] 80 stator column

[0117] 201 thread groove spacer shaft vertical part

[0118] 202 thread groove spacer shaft parallel part

[0119] 300 vertical part mountain part

[0120] 400 vertical valley

[0121] 500 parallel part mountain part

[0122] 550 Cap

[0123] 600 parallel valley

[0124] 700 fixing bolt

[0125] 710 Head

[0126] 800 countersunk hole

[0127] 900 Cartridge Heater

[0128] 910 bolt

[0129] X Setting Surface

[0130] 1001Previous vacuum pump

[0131] Single-path thread groove spacers from 2001.

Claims

1. A vacuum pump comprising an outer casing, a fixing part, a sigebain pump part, and a thread groove pump part, The outer casing is formed with an air intake port or an air exhaust port. The fixing part is built into the outer casing. The Sigbain pump unit has a stator, the stator has a spiral groove, the spiral groove has a first mountain portion, a second mountain portion, and a valley portion arranged between the radial outer side of the first mountain portion and the radial inner side of the second mountain portion. The vacuum pump is characterized in that: A connecting type thread groove spacer is provided, wherein the connecting type thread groove spacer has a structure for connecting the Sigma pump part and the thread groove pump part, A countersunk hole is provided on the exhaust gas flow path surface of the valley portion of the Sigbain pump portion in the connecting type thread groove spacer, and the connecting type thread groove spacer and the outer body or the fixing part are fastened and connected by means of a fixing bolt arranged in the countersunk hole. The counterbore is arranged closer to the outer side of the first peak portion than to the inner side of the second peak portion.

2. The vacuum pump according to claim 1, characterized in that The counterbore is provided on the exhaust gas flow path surface located radially outside the valley portion of the sigebain pump portion.

3. The vacuum pump according to claim 2, characterized in that The fixing bolt disposed in the countersunk hole has its upper portion covered by a cap.

4. A connecting type thread groove spacer, used for a vacuum pump having an outer body, a fixing part, a sigbain pump part, and a thread groove pump part, wherein the outer body is formed with an air intake port or an air exhaust port, the fixing part is built into the outer body, the sigbain pump part has a stator, the stator has a spiral groove, the spiral groove has a first peak part, a second peak part, and a valley part arranged between the radial outer side of the first peak part and the radial inner side of the second peak part, The aforementioned connecting type thread groove spacer is characterized in that: The connecting type thread groove spacer has a structure for connecting the Sigma pump part and the thread groove pump part. The exhaust gas flow path surface of the valley portion of the Sigbain pump portion in the connecting type thread groove spacer is provided with a countersunk hole for fixing bolts, and is fastened and connected to the outer body or the fixing part by means of the fixing bolts. The counterbore is arranged closer to the outer side of the first peak portion than to the inner side of the second peak portion.

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