Shell stator for vacuum pump
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- EDWARDS LTD
- Filing Date
- 2023-08-30
- Publication Date
- 2026-07-24
AI Technical Summary
Rotary machines, such as compressors or vacuum pumps, face challenges in providing effective seals due to fluid flow assisted by pressure differentials, leading to sealing issues.
A shell stator with seal grooves featuring biasing means, including protrusions and recesses, is used to position and bias a seal gasket, ensuring precise sealing by using deformable elastomeric materials and continuous, smooth geometries to accommodate thermal and mechanical changes.
The solution effectively seals the vacuum pump, reducing leakage and facilitating easy assembly and maintenance by allowing the gasket to expand and contract without damaging, thus enhancing operational reliability and reducing pinch points.
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a shell stator for a vacuum pump and to a vacuum pump. [Background technology]
[0002] Rotary machines, such as compressors or vacuum pumps, require careful design and manufacture so that moving parts cooperate precisely with one another. Providing effective seals to seal the machines tends to be problematic, especially when fluid flow is assisted by a pressure differential between the machine and the surrounding environment. It would be desirable to provide an improved seal. Summary of the Invention [Means for solving the problem]
[0003] In one aspect, a shell stator for a vacuum pump is provided. The shell stator includes a seal groove formed in a surface of the shell stator, the seal groove being defined by a first sidewall, a second sidewall opposing the first sidewall, and a bottom surface disposed between the first sidewall and the second sidewall, the bottom surface being opposite an opening of the seal groove. The seal groove includes a biasing means for biasing a seal gasket in the seal groove (e.g., to a specific position within the seal groove). The biasing means includes a protrusion formed in the first sidewall and extending toward the second sidewall, and a recess formed in the second sidewall facing the protrusion.
[0004] The protrusion may be a continuous curved bump.
[0005] The recess may be a continuous curved recess.
[0006] The seal groove can include a plurality of protrusions formed in the first side wall and extending toward the second side wall, and a plurality of recesses formed in the second side wall, each recessed portion of the plurality of recesses facing a respective protrusion of the plurality of protrusions.
[0007] The seal groove may be formed in an abutment surface of the shell stator, the abutment surface being for receiving a further shell stator, thereby defining at least one pumping chamber.
[0008] The seal groove may be formed in an end face of the shell stator, the end face being for receiving the end piece.
[0009] The shell stator may further include an additional seal groove formed in the surface of the shell stator, the additional seal groove being defined by a third sidewall, a fourth sidewall opposing the third sidewall, and an additional bottom surface disposed between the third sidewall and the fourth sidewall, the additional bottom surface being on the opposite side of the opening of the additional seal groove. The additional seal groove may include an additional protrusion formed in the third sidewall and extending toward the fourth sidewall, and an additional recess formed in the fourth sidewall opposing the additional protrusion. The first sidewall and the third sidewall may be outermost walls. The second sidewall and the fourth sidewall may be innermost walls. The shell stator may further include a curved seal groove formed in the end surface of the shell stator, the curved seal groove being formed between the seal groove and the additional seal groove.
[0010] In a further aspect, a system is provided that includes the shell stator of any of the above aspects and a seal gasket disposed within the seal groove, wherein the protrusion biases at least a portion of the seal gasket toward or against a particular position within the seal groove (e.g., against the second side wall). The thickness of the seal gasket in a direction from the first side wall to the second side wall may be less than the size of the seal groove in this direction.
[0011] The seal gasket may have a substantially uniform thickness.
[0012] In a further aspect, a vacuum pump is provided, comprising: shell stators defining at least one pumping chamber, at least one of the shell stators being a shell stator according to any of the above aspects; end pieces attached to either end of the shell stators; and a seal gasket disposed between the shell stators and the end pieces and disposed in a seal groove; wherein the protrusion biases at least a portion of the seal gasket against the second side wall.
[0013] At least one of the shell stators may further include an additional seal groove formed in the surface of the shell stator, the additional seal groove being defined by a third sidewall, a fourth sidewall opposing the third sidewall, and an additional bottom surface disposed between the third sidewall and the fourth sidewall, the additional bottom surface being on the opposite side of the opening of the additional seal groove. The additional seal groove may include an additional protrusion formed in the third sidewall and extending toward the fourth sidewall, and an additional recess formed in the fourth sidewall opposing the additional protrusion. The first sidewall and the third sidewall may be outermost walls with respect to the at least one pump chamber. The second sidewall and the fourth sidewall may be innermost walls with respect to the at least one pump chamber. A seal gasket may also be disposed in the additional seal groove. The protrusion and the additional protrusion may bias at least a portion of the seal gasket against the innermost sidewall.
[0014] The vacuum pump may further include two closed-shaped seal grooves, each formed at a respective end of the shell stator. The seal gasket may include two seal members each defining a closed shape, each disposed in a respective one of the closed-shaped seal grooves. Each closed-shaped seal groove may be defined by an outer wall, an inner wall opposing the outer wall, and a bottom surface disposed between the outer wall and the inner wall, the bottom surface being on the opposite side of the opening of the closed-shaped seal groove. Each closed-shaped seal groove may include a protrusion formed in the outer wall and extending toward the inner wall, and a recess formed in the inner wall opposite the protrusion, the protrusion of the closed-shaped seal groove biasing at least a portion of the seal member disposed in the closed-shaped sheet groove against the inner wall of the closed-shaped seal groove.
[0015] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]
[0016] [Figure 1] 1 is a schematic diagram (not to scale) showing the housing of a vacuum pump. [Figure 2] FIG. 1 is a schematic diagram of a sealing gasket (not to scale). [Figure 3] 1 is a further schematic view of a sealing gasket (not to scale); FIG. [Figure 4] 1 is a process flow chart illustrating certain steps of a method for assembling a seal gasket into a housing. [Figure 5] FIG. 1 is a schematic diagram (not to scale) showing a sealing gasket positioned within a housing. [Figure 6] 1 is a schematic diagram (not to scale) showing a top view of a first longitudinal seal member positioned within a first longitudinal seal groove; [Figure 7] 1 is a schematic diagram (not to scale) showing a first closed shape seal member positioned within a first closed shape seal groove; DETAILED DESCRIPTION OF THE INVENTION
[0017] FIG. 1 is a schematic diagram (not to scale) illustrating a housing 10 of a vacuum pump according to one embodiment. The housing 10 comprises a pair of shell stators 12, 14 and a pair of end plates 16, 18. The shell stators 12, 14 define recesses that receive components of the vacuum pump. The shell stators 12, 14 fit together to hold the components within the recesses. The end plates 16, 18 are then brought to hold the shell stators 12, 14. This allows for convenient assembly of the vacuum pump.
[0018] In other words, the vacuum pump housing 10 may be formed from multiple components, including shells 12, 14 and end plates 16, 18, which must be sealed together when assembled. In the configuration shown in Figure 1, the stator is formed by assembling two housing parts or shells 12, 14 held between a pair of end plates 16, 18.
[0019] As described in more detail below, in this embodiment, one or more (e.g., two) longitudinal seals are disposed along the mating surfaces of the shell stators 12, 14 to adequately seal the shell stators 12, 14. Additionally, a pair of seals (e.g., annular seals in some embodiments) defining a closed shape are disposed between the end plates 16, 18 and the shell stators 12, 14 to adequately seal between the shell stators 12, 14 and their respective end plates 16, 18.
[0020] FIG. 2 is a schematic diagram (not to scale) of a sealing gasket 20 for sealing the housing 10, according to one embodiment.
[0021] The sealing gasket 20 includes a first closed-shaped sealing member 22 (which may be generally annular), a second closed-shaped sealing member 24 (which may be generally annular), a first longitudinal sealing member 26, and a second longitudinal sealing member 28.
[0022] The first closed shape seal member 22 includes a first surface 30, a second surface 32 opposite the first surface 30, a first radially inner surface 34, and a first radially outer surface 36 opposite the first radially inner surface 34. The first radially inner surface 34 and the first radially outer surface 36 are disposed between the first surface 30 and the second surface 32.
[0023] The second closed shape seal member 24 includes a third surface 40, a fourth surface 42 opposite the third surface 40, a second radially inner surface 44, and a second radially outer surface 46 opposite the second radially inner surface 44. The second radially inner surface 44 and the second radially outer surface 46 are disposed between the third surface 40 and the fourth surface 42.
[0024] The first longitudinal seal member 26 is bonded or attached between the first radially outer surface 36 (of the first closed shape seal member 22) and the second radially outer surface 46 (of the second closed shape seal member 24).
[0025] The second longitudinal seal member 28 is bonded or attached between the first radially outer surface 36 (of the first closed shape seal member 22) and the second radially outer surface 46 (of the second closed shape seal member 24).
[0026] The second longitudinal seal member 28 is disposed opposite the first longitudinal seal member 26. That is, the second longitudinal seal member 28 is coupled to the first and second closed shape seal members 22, 24 on the opposite side of the first and second closed shape seal members 22, 24 from the side on which the first longitudinal seal member 26 is coupled to the first and second closed shape seal members 22, 24.
[0027] The first closed shape seal member 22 defines a closed shape and may be a ring-shaped seal member. The first closed shape seal member 22 has a square or rectangular cross section.
[0028] The second closed shape seal member 24 defines a closed shape and may be a ring-shaped seal member. The second closed shape seal member 24 has a square or rectangular cross section.
[0029] The first longitudinal seal member 26 may be an O-ring cord that may have a circular cross section. The first longitudinal seal member 26 may have a square or rectangular cross section.
[0030] The second longitudinal seal member 28 may be an O-ring cord that may have a circular cross section. The second longitudinal seal member 28 may have a square or rectangular cross section.
[0031] In this embodiment, the sealing gasket 20 is a continuous, one-piece sealing gasket.
[0032] The sealing gasket 20 is made of a deformable or flexible material, such as an elastomeric material (e.g., a fluoroelastomer (FKM / FPM) or a perfluoroelastomer (FFKM)) or silicone, such that the sealing gasket 20 is deformable or flexible. Thus, the sealing gasket 20 can be deformed into a desired shape or configuration suitable for use as a seal for the housing 10.
[0033] FIG. 3 is a schematic diagram (not to scale) showing the sealing gasket 20 modified into a configuration suitable for sealing the housing 10.
[0034] In this configuration, the first and second closed shape seal members 22, 24 are square ring-shaped members with curved corners. This configuration has major surfaces (first radially inner surface 34 and first radially outer surface 36 of the first closed shape seal member 22, and second radially inner surface 44 and second radially outer surface 46 of the second closed shape seal member 24) that abut major surfaces of the end plates 16, 18 and adjacent surfaces of the shell stators 12, 14 in use. In this example, the first and second closed shape seal members 22, 24 have substantially planar axial outer surfaces provided by the first radially inner surface 34 and second radially inner surface 44, respectively. The first and second closed shape seal members 22, 24 have substantially planar axial inner surfaces provided by the first radially outer surface 36 and second radially outer surface 46, respectively. The longitudinal seal member 26 is coupled between the opposing axially inner surfaces (i.e., between the first radially outer surface 36 and the second radially outer surface 46) of the first and second closed-form seal members 22, 24. The annular seal members 22, 24 have a substantially constant thickness.
[0035] FIG. 4 is a process flow diagram illustrating certain steps (s40-s48) of a method for fitting, installing, or assembling the sealing gasket 20 to the housing 10.
[0036] FIG. 5 is a schematic diagram (not to scale) showing the assembly of the sealing gasket 20 into the housing 10.
[0037] In step s40, a shell stator 14 is provided into which the vacuum pump components may be assembled.
[0038] In step s42, the sealing gasket 20 is positioned relative to the shell stator 14 so that the first and second longitudinal seal members 26, 28 are positioned along the mating surface of the shell stator 14. The longitudinal seal members 26, 28 are positioned within respective longitudinal seal grooves 50, 52 that extend along the mating surface of the shell stator 14, as shown in FIG.
[0039] The longitudinal seal grooves 50, 52 and the placement of the longitudinal seal members 26, 28 therein are described in more detail below with reference to FIG.
[0040] In step s44, the shell stator 12 is brought into intimate contact with the longitudinal seal members 26, 28. Specifically, the shell stator 12 is moved onto the longitudinal seal members 26, 28 toward the mating surfaces of the shell stator 14. Figure 5 shows the shell stators 12, 14 positioned in this manner.
[0041] In step s46, the shell stators 12, 14 are clamped together, which compresses the longitudinal seal members 26, 28. The shell stators 12, 14 are secured together to form a pumping chamber.
[0042] After step s46, the first and second closed-form seal members 22,24 tend to extend or protrude axially from the axial ends of the combined shell stators 12,14.
[0043] In step s48, the end plates 16, 18 are brought together to axially (ie, longitudinally) compress the first and second closed-configuration seals 26, 28.
[0044] The first and second closed-form seal members 22,24 may be positioned in closed-form (eg, loop-shaped) seal grooves positioned in the shell stators 12,14 and / or end plates 16,18.
[0045] The closed seal grooves 54, 56 and the positioning of the first and second closed seal members 22, 24 therein are described in more detail below with reference to FIG.
[0046] 5, end plate 18 is shown moved onto first annular seal member 22 at a first end of assembled shell stators 12, 14. End plate 16 can be moved onto second annular seal member 24 at a second end (opposite the first end) of assembled shell stators 12, 14, as indicated by arrow and reference numeral 58 in FIG.
[0047] Thus, a method for fitting, mounting, or assembling the sealing gasket 20 to the housing 10 is provided.
[0048] 6 is a schematic diagram (not to scale) showing a top view of the first longitudinal seal member 26 positioned within the first longitudinal seal groove 52. Those skilled in the art will appreciate that the second longitudinal seal member 28 is positioned within the second longitudinal seal groove 50 in a similar manner.
[0049] A first longitudinal seal groove 52 extends along and is formed in the mating surface of the shell stator 14 .
[0050] The first longitudinal seal groove 52 includes a first sidewall 60, a second sidewall 62 opposite the first sidewall 60, and a bottom surface 64 disposed between the first sidewall 60 and the second sidewall 62. The first sidewall 60 is the surface of the first longitudinal seal groove 52 farthest from the pump chamber(s). The second sidewall 62 is the surface of the first longitudinal seal groove 52 closest to the pump chamber(s). The bottom surface 64 is opposite the opening of the first longitudinal seal groove 52.
[0051] The first longitudinal seal groove 52 includes a biasing means 66 for biasing the first longitudinal seal groove 52 against the second side wall 62. In this embodiment, there are multiple biasing means 66 spaced along the length of the first longitudinal seal groove 52.
[0052] Each biasing means 66 includes a respective protrusion 68 and a respective recess 69. The protrusion 68 is formed on the first side wall 60. The protrusion 68 extends from the first side wall 60 toward the second side wall 62. The recess 69 is formed on the second side wall 62 opposite the protrusion 68.
[0053] Seal grooves such as the first and second longitudinal seal grooves 50, 52 can provide a leakage path for gas between the low and high vacuum ends of the pump. In this embodiment, the longitudinal seal members 26, 28 are biased against the pump chamber side of the longitudinal seal grooves 50, 52 (i.e., inward most relative to the pump chamber(s)). This advantageously tends to block this leakage path.
[0054] In this embodiment, the first and second longitudinal seal grooves 50, 52 are wider than the longitudinal seal members 26, 28 positioned therein, which tends to provide some lateral freedom of movement as well as the ability for the seal gasket 20 to expand due to, for example, heating and / or compression of the seal gasket 20.
[0055] In some embodiments, one or more protrusions are formed on the second sidewall and extend toward the first sidewall, and one or more recesses are formed on the first sidewall opposite each protrusion.
[0056] Preferably, each of the longitudinal seal grooves 50, 52 has a constant width and therefore tends to be machineable in one pass using a single tool. This tends to be advantageous over grooves that include, for example, one or more narrowed sections to grip the sealing gasket. Furthermore, the lack of such narrowed sections tends to reduce the likelihood of pinch points in the gasket as it expands under compression and temperature changes.
[0057] 7 is a schematic diagram (not to scale) showing first closed shape seal member 22 positioned in first closed shape seal groove 54. Those skilled in the art will appreciate that second closed shape seal member 24 may be positioned in second closed shape seal groove 56 in a similar manner.
[0058] The first closed seal groove 54 may be formed in the end faces of the shell stators 12 , 14 and / or the mating surfaces of the end plates 18 .
[0059] The closed seal groove 54 includes a first sidewall 70, a second sidewall 72 opposing the first sidewall 70, and a bottom surface 74 disposed between the first sidewall 70 and the second sidewall 72. The first sidewall 70 is the surface of the first closed seal groove 54 that is farthest from the center of the closed shape defined by the first closed seal groove 54. The second sidewall 72 is the surface of the first closed seal groove 54 that is closest to the center of the closed shape defined by the first closed seal groove 54. The bottom surface 74 is opposite the opening of the first closed seal groove 54.
[0060] The first closed shape seal groove 54 includes a biasing means 76 that biases the first closed shape seal groove 54 toward a central portion of the first closed shape seal groove 54. In this embodiment, there are multiple biasing means 76 arranged in a spaced apart configuration around the first closed shape seal groove 54. For clarity, only some of the biasing means 76 are labeled in FIG. 7 .
[0061] Each biasing means 76 includes a respective protrusion 78 and a respective recess 79. The protrusion 78 is formed on either the first side wall 70 or the second side wall 72 and extends toward the opposite side wall 70, 72. The recess 79 is formed on the other of the second side wall 72 or the first side wall 70, opposite the protrusion 78.
[0062] In this embodiment, the first and second closed shape seal grooves 54, 56 are wider than the first and second closed shape seal members 22, 24 positioned therein. This tends to provide some lateral / radial freedom of movement as well as the ability for the seal gasket 20 to expand due to, for example, heating and / or compression of the seal gasket 20. Additionally, biasing the first and second closed shape seal members 22, 24 toward the central portions of the closed shape seal grooves 54, 56 tends to allow the seal members 22, 24 to expand in both a radially inward and radially outward direction.
[0063] Preferably, each of the closed seal grooves 54, 56 has a constant width and therefore tends to be machined in one pass using a single tool. This tends to be advantageous over grooves that include, for example, one or more narrowed sections to grip the seal gasket. Furthermore, the lack of such narrowed sections tends to reduce the likelihood of pinch points in the gasket as the gasket expands under compression or temperature changes.
[0064] In the above embodiments, each protrusion may be a continuous curved bump or bumps. Preferably, the protrusions do not include discontinuities or sharp corners, i.e., they are smooth. This advantageously tends to reduce the likelihood of damaging the sealing gasket.
[0065] In the above embodiments, each recess may be a continuous curved recess, cavity, or void. Preferably, the recesses do not include discontinuities or sharp corners, i.e., they are smooth. This advantageously tends to reduce the likelihood of damaging the sealing gasket.
[0066] The use of a biasing or positioning means that uses only structural features of the seal groove to position the sealing gasket within the seal groove tends to advantageously allow for the use of sealing gaskets having simpler geometries, which tends to facilitate the design, manufacture, and cost of the sealing gasket, which tends to require repair or replacement relatively frequently compared to, for example, a shell stator or end plate.
[0067] The sealing gaskets tend to be easily attached to the housing or vacuum pump.
[0068] It should be understood that the cord and gasket may have various shapes or thicknesses to suit the configuration of the housing.
[0069] In the above embodiments, the seal gasket is a continuous, one-piece seal gasket. However, in other embodiments, the seal gasket comprises multiple separate parts that are joined together. The multiple parts can be joined together by any joining means or method, such as using an adhesive, using fusing, or using an interference fit.
[0070] In the above embodiments, the seal gasket has a substantially constant cross-section across the part. However, in other embodiments, the seal gasket has a non-constant cross-section.
[0071] In the above embodiments, the sealing gasket has a square or rectangular cross section. However, in other embodiments, some or all of the sealing gasket has an alternative cross section other than square or rectangular, such as circular, triangular, oval, etc.
[0072] In the above embodiments, the sealing gasket may be made of an elastomer. In some embodiments, the sealing gasket may be made of another deformable material, such as a metal.
[0073] It will be appreciated that although the major surfaces of the sealing gaskets in the above embodiments are substantially planar, they may be of any suitable shape suitable for engaging the major surfaces of the end plates and the adjacent surfaces of the shell stators.
[0074] Although exemplary embodiments of the present invention are disclosed in detail herein with reference to the accompanying drawings, it should be understood that the present invention is not limited to the precise embodiments, and that various changes and modifications may be made therein by those skilled in the art without departing from the scope of the present invention as defined by the appended claims and their equivalents. [Explanation of symbols]
[0075] 10. Housing 12, 14 Shell stator 16, 18 End plates 20 sealing gasket 22 first closed shape seal member 24 second closed-shape seal member 26 first longitudinal seal member 28 second longitudinal seal member 30 First Surface 32 Second Surface 34 first radially inner surface 36 first radially outer surface 40 The Third Surface 42 The Fourth Surface 44 second radially inner surface 46 second radially outer surface S40-48 Method Steps 50, 52 Longitudinal seal groove 54, 56 Closed seal groove 60 first side wall of longitudinal seal groove 62 second side wall of longitudinal seal groove 64 Bottom of longitudinal seal groove 66 Longitudinal seal groove biasing means 68 Protrusion 69 Recess 70 first side wall of closed seal groove 72 Second side wall of closed seal groove 74 Bottom of closed seal groove 76 Biasing means for closed seal groove 78 Protrusion 79 Depression
Claims
1. A shell stator for a vacuum pump, The shell stator is provided with a seal groove formed on the surface of the shell stator, the seal groove being defined by a first side wall, a second side wall opposite the first side wall, and a bottom surface disposed between the first side wall and the second side wall, the bottom surface being on the opposite side of the opening of the seal groove. The aforementioned seal groove is A projection formed on the first side wall and extending toward the second side wall, A recess is formed in the second side wall and faces the protruding portion, A shell stator equipped with this feature.
2. The shell stator according to claim 1, wherein the protruding portion is a continuous curved bump.
3. The shell stator according to claim 1, wherein the recessed portion is a continuous curved recessed portion.
4. The aforementioned seal groove is A plurality of protrusions formed on the first side wall and extending toward the second side wall, Multiple recesses formed in the second side wall, The shell stator according to claim 1, comprising, wherein each of the plurality of recesses faces each of the plurality of projections.
5. The shell stator according to claim 1, wherein the seal groove is formed on the joint surface of the shell stator, and the joint surface is for receiving a further shell stator, thereby defining at least one pump chamber.
6. The shell stator according to claim 1, wherein the seal groove is formed on the end face of the shell stator, and the end face is for receiving an end piece.
7. The shell stator further comprises a further sealing groove formed on its surface, wherein the further sealing groove is defined by a third side wall, a fourth side wall opposite to the third side wall, and a further bottom surface positioned between the third side wall and the fourth side wall, the further bottom surface being on the opposite side of the opening of the further sealing groove. The aforementioned further sealing groove is A further projection formed on the third side wall and extending toward the fourth side wall, A further recess is formed in the fourth side wall and is opposite to the further protrusion, A shell stator according to claim 1, comprising:
8. The shell stator according to claim 7, wherein the first and third side walls are the outermost walls, and the second and fourth side walls are the innermost walls.
9. The shell stator according to claim 7, further comprising a curved seal groove formed on the end face of the shell stator, wherein the curved seal groove is formed between the seal groove and the further seal groove.
10. A shell stator according to any one of claims 1 to 9, A seal gasket placed in the seal groove, A system equipped with, The system wherein the protrusion biases at least a portion of the seal gasket against the second side wall.
11. The system according to claim 10, wherein the thickness of the seal gasket in the direction from the first side wall to the second side wall is smaller than the size of the seal groove in that direction.
12. The system according to claim 10, wherein the seal gasket has a substantially uniform thickness.
13. A shell stator defining at least one pump chamber, wherein at least one of the shell stators is a shell stator according to any one of claims 1 to 9, An end piece attached to one end of the aforementioned shell stator, A seal gasket is positioned between the shell stator and the end piece and within the seal groove, A vacuum pump equipped with, The aforementioned protrusion biases at least a portion of the seal gasket against the second side wall of the vacuum pump.
14. At least one of the shell stators further comprises a further sealing groove formed on the surface of the shell stator, the further sealing groove being defined by a third side wall, a fourth side wall opposite the third side wall, and a further bottom surface positioned between the third side wall and the fourth side wall, the further bottom surface being on the opposite side of the opening of the further sealing groove. The aforementioned seal groove is A further projection formed on the third side wall and extending toward the fourth side wall, A further recess is formed in the fourth side wall and is opposite to the further protrusion, Equipped with, The first side wall and the third side wall are the outermost walls to the at least one pump chamber, The second side wall and the fourth side wall are the innermost walls to the at least one pump chamber, The seal gasket is similarly positioned within the further seal groove, The vacuum pump according to claim 13, wherein the protrusion and the further protrusion bias at least a portion of the seal gasket against the innermost side wall.
15. It further features two closed sealing grooves, Each closed seal groove is formed at the respective end of the shell stator, The seal gasket comprises two sealing members, each defining a closed shape, and each of the sealing members is positioned in each of the closed seal grooves. Each of the closed seal grooves is defined by an outer wall, an inner wall opposite the outer wall, and a bottom surface positioned between the outer wall and the inner wall, the bottom surface being on the opposite side of the opening of the closed seal groove. The aforementioned closed seal groove is A projection formed on the outer wall and extending toward the inner wall, A recess formed in the inner wall opposite the protruding portion, Equipped with, The vacuum pump according to claim 13, wherein the protrusion of the closed seal groove biases at least a portion of the seal member disposed within the closed seal groove against the inner wall of the closed seal groove.