One-piece sealing gasket for a vacuum pump

Abstract

Embodiments relate to a one-piece sealing gasket for sealing in multiple planes in a vacuum pump. The sealing gasket comprises: a first sealing member (11a) defining a closed shape, a second sealing member (11b) defining a closed shape, a first longitudinal sealing member (12a) interconnecting the first and the second sealing member, and a second longitudinal sealing member (12b) interconnecting the first and the second sealing member. The first and second longitudinal sealing members each comprise a plurality of longitudinally staggered protrusions (13) extending in a first plane from the first and second longitudinal sealing members, the first plane being defined by the first and second longitudinal sealing members. When the first and second longitudinal sealing members are received within a respective groove of the vacuum pump, each of the plurality of protrusions is configured to engage a side wall of the respective groove such that the first and second longitudinal sealing members are deformed to adopt a tortuous path within the respective groove.

Description

[0001] ONE-PIECE SEALING GASKET FOR A VACUUM PUMP

[0002] FIELD OF THE INVENTION

[0003] The field of the invention relates to a one-piece sealing gasket for a vacuum pump and a vacuum pump comprising the one-piece sealing gasket.

[0004] BACKGROUND

[0005] Vacuum pumps, such as multi-stage roots pumps, may require seals in multiple planes. For example, a vacuum pump may be formed by a pair of stator halfsections for housing a pumping mechanism and a pair of end plates mounted to either end of the stator half-sections for retaining the pumping mechanism within the stator sections. Conventionally, four gaskets are used to seal the vacuum pump. Two longitudinal gaskets are used for sealing between the stator halfsections in a first plane and two annular gaskets are used for sealing between the end plates and the ends of the stator half-sections in a second plane. However, there may be weaknesses at the joints between the gaskets which could lead to leakages. Furthermore, manufacturing four separate gaskets can be expensive.

[0006] One-piece sealing gaskets have been developed for sealing the vacuum pump without the need for multiple gaskets. Typically, a one-piece sealing gasket comprises two bar-shaped longitudinal sealing members dimensioned to fit tightly within a groove defined in one of the stator half-sections. However, due to the differing thermal expansion coefficients of the sealing gasket and the stator halfsection, the integrity of the seal may become compromised when the temperature of the components changes.

[0007] It would be desirable to provide an improved one-piece sealing gasket which overcomes at least one of the above-mentioned drawbacks.

[0008] SUMMARY

[0009] According to an aspect, there is provided a one-piece sealing gasket for sealing in multiple planes in a vacuum pump, the sealing gasket comprising: a first sealing member defining a closed shape; a second sealing member defining a closed shape; a first longitudinal sealing member interconnecting the first and the second sealing member; and a second longitudinal sealing member interconnecting the first and the second sealing member, the first and second longitudinal sealing members each comprising a plurality of longitudinally staggered protrusions extending perpendicularly to a longitudinal direction defined by the respective longitudinal sealing member, and when the first and second longitudinal sealing members are received within a respective groove of the vacuum pump, each of the plurality of protrusions is configured to engage a side wall of the respective groove such that the first and second longitudinal sealing members are deformed to adopt a tortuous path within the respective groove.

[0010] Vacuum pumps, such as multi-stage roots pumps, may require seals in multiple planes. Some vacuum pumps are formed by a pair of stator sections (e.g., stator half-shells) mountable together to define one or more recesses for housing the components of the vacuum pump such as the pumping mechanism. A pair of end plates may be used to retain the pumping mechanism within the stator sections. The joint between the stator sections tends to be perpendicular to the joint between the end plates and the stator sections. Traditionally, individual longitudinal or linear gaskets have been used to seal along and between the stator sections whilst separate closed shape or annular gaskets have been used to seal between the end plates and the stator sections. However, there may be weaknesses at the joints where the annular and the longitudinal gaskets meet which could lead to leakages. Furthermore, manufacturing four separate gaskets may be expensive.

[0011] One-piece sealing gaskets have been developed for sealing between the stator sections as well as between the end plates and the stator sections without the need for multiple gaskets, thus avoiding having any junctions between separate gaskets. The longitudinal sealing members of these one-piece sealing gaskets are typically straight to fit into grooves defined in one of the stator sections. However, this form of longitudinal sealing member may have drawbacks.

[0012] For example, to provide a good seal, a typical straight longitudinal sealing member should have a tight fit within the groove such that a seal is formed against both side walls of the groove. However, it may be difficult to maintain this tight fit because the gasket and the stator section are typically made from different materials and so have different thermal expansion coefficients. For example, the gasket may be formed from an elastomer and the stator sections made form a metal such as aluminium. During operation of the pump, the temperature of these components may vary leading to thermal expansion and contraction. Due to the different thermal expansion coefficients, the integrity of the seal may become compromised.

[0013] Further, if the geometry of the groove includes curved corners or chamfered edges, a simple straight longitudinal sealing member may be susceptible to minor leaks along its length which can reduce pumping performance. Moreover, if the one-piece gasket is retrofitted to a pre-existing pump, the longitudinal sealing member may not be designed specifically for that pump and so the longitudinal sealing member may not fit tightly into the groove leading to a sub-optimal seal.

[0014] The present invention provides a plurality of protrusions on each of the longitudinal sealing members of a one-piece gasket. These protrusions are configured to engage the side walls of the grooves within which the longitudinal sealing members are received such that the main body of the longitudinal sealing members is forced to adopt a tortuous or snake-like path within the grooves. Importantly, a stronger seal may be formed against both side walls compared to a longitudinal sealing member without the protrusions because the resistance of the longitudinal sealing members to being bent biases the protrusions into the side walls of the grooves to form the seal. Consequently, it is no longer necessary for the main body of the longitudinal sealing members to be dimensioned precisely to fit tightly within the groove to form the seal - i.e. , the width of the longitudinal member does not need to be substantially the same width as the groove, it can be narrower. This means that the present gasket may form an effective seal for a variety of groove shapes and dimensions compared to the standard straight edge longitudinal seal members. This may allow for backwards compatibility with more vacuum pump models.

[0015] Furthermore, as the protrusions are staggered and as the main body of the longitudinal sealing members may not take up the entire width of the groove, there is space within the groove to accommodate thermal expansion. As a result, the gasket’s resilience to thermal expansion is improved and the reliability of the gasket improved.

[0016] In this context, a one-piece sealing gasket means that the components of the sealing gasket are integrally formed with one another such that the sealing gasket is monolithically formed.

[0017] In this context, longitudinally staggered means spread along the length of the longitudinal sealing members at different points, i.e. , no two protrusions extend from the same point along the length of the sealing member.

[0018] In some embodiments, the sealing gasket is configured to deform from an initial planar state in which the first and second sealing members and the first and second longitudinal sealing members are in a first plane defined by the first and second longitudinal sealing members to a three-dimensional state in which the first and second sealing members are twisted with respect to the first and second longitudinal sealing members to define a second plane that is different to the first plane. In this way, the gasket may be manufactured in one plane as a flat two- dimensional gasket. Once manufactured, the first and second sealing members of the sealing gasket may be twisted or otherwise manipulated into the second plane when the vacuum pump is assembled. Such one-piece sealing gaskets may be easy to manufacture and cost effective. In some embodiments, the plurality of protrusions extend from alternate sides of the first and second longitudinal sealing members. By having protrusions on alternating sides, the gasket provides a strong seal on both sides of the groove and forces the longitudinal sealing members to adopt the tortuous path within the groove. As a result, gas leakage along the length of the longitudinal sealing members may be reduced.

[0019] In some embodiments, the plurality of protrusions comprises at least three protrusions. Providing three protrusions forces the longitudinal sealing members to adopt the tortuous path necessary for creating a secure seal on both sides of the groove. In particular, the longitudinal sealing members are biased towards a first side of the groove by the first protrusion, then towards the opposite side of the groove by the second protrusion, and back towards the first side of the groove by the third protrusion.

[0020] In some embodiments, the plurality of protrusions comprises at least five protrusions. Minor leaks may occur around the gasket due to the geometry of the groove in which it is positioned. For example, rounded corners and chamfered edges can create leakage paths. By increasing the number of protrusions, the gasket has more contact / sealing points within the groove which can mitigate the effects of minor leaks along the longitudinal sealing members.

[0021] In some embodiments, the plurality of protrusions are staggered such that the protrusions do not overlap in the longitudinal direction. This may help create space to accommodate thermal expansion of the gasket whilst the protrusions maintain an effective seal within the groove.

[0022] In some embodiments, the first and second longitudinal sealing members are configured to bias the plurality of protrusions against the side wall of the respective grooves to form a seal. The urge for the longitudinal sealing members to straighten out from their tortuous path within the grooves of the vacuum pumps provides a spring-like force pushing the protrusions against the side walls of the groove. This may increase the strength of the seal and inhibit leakage.

[0023] In some embodiments, the plurality of protrusions have a semi-circular crosssection. In this way, the protrusions may distribute force evenly to the main body of the longitudinal sealing member and maintain a consistent contact with the side wall of the groove.

[0024] In some embodiments, the first and the second longitudinal sealing members have a rectangular cross-section, and the plurality of protrusions extend from side surfaces of the first and second longitudinal sealing members. Having the protrusions on the side surface of the straight longitudinal sealing members allows for ease of manufacture and modification of dies for moulding the gasket.

[0025] In some embodiments, the second plane is substantially perpendicular to the first plane.

[0026] In some embodiments, the first and second longitudinal sealing members are for sealing along and between a first and a second stator section of the vacuum pump. Sealing along the first and second stator section inhibits leakage between the stages of a multi-stage vacuum pump. Sealing between the first and second stator section inhibits the passage of gas between the inside and outside of the vacuum pump.

[0027] In some embodiments, the plurality of protrusions are evenly distributed about an approximate centre of the first and second longitudinal sealing members. In this way, the protrusions may be positioned to inhibit leakage between the stages of a multi-stage vacuum pump.

[0028] In some embodiments, the first and second sealing members are for sealing between respective ends of the first and second stator sections and a first and a second end plate of the vacuum pump, respectively. In some embodiments, the sealing gasket is formed from an elastomer.

[0029] Elastomers may have the elasticity, flexibility and deformability necessary to make the one-piece sealing gasket.

[0030] In some embodiments, the sealing gasket is a moulded gasket.

[0031] In some embodiments, the first and the second sealing members have a circular cross-section. In this way, the sealing members are rotationally symmetric at all angles. Therefore, if the first and second sealing members were to be twisted into the second plane, the shape of the sealing members is not substantially changed and an effective seal may still be formed.

[0032] In some embodiments, the first sealing member and the second sealing member define identical closed shapes. In some embodiments, the first and second sealing members are annular or ring-shaped.

[0033] In some embodiments, the first longitudinal sealing member and the second longitudinal sealing member connect to opposite sides of the closed shape defined by the first and second sealing members.

[0034] In some embodiments, the sealing gasket comprises a poka-yoke formation for engaging a recess of the vacuum pump to aid positioning of the sealing gasket within the vacuum pump. A poka-yoke formation may be formed on one or more of the following: the first sealing member, the second sealing member, the first longitudinal sealing member, and the second longitudinal sealing member. The poka-yoke formation helps to ensure the gasket is correctly positioned within the vacuum pump.

[0035] According to another aspect, there is provided a vacuum pump comprising: a first stator section; a second stator section mounted to the first stator section such that the first and second stator sections together define a pumping chamber housing a pumping mechanism of the vacuum pump, the pumping mechanism being configured to pump gas from an inlet to an outlet of the vacuum pump; a first end plate mounted to a first end of the first and second stator sections; a second end plate mounted to a second end of the first and second stator sections, the first and second end plates being configured to retain the pumping mechanism within the pumping chamber; and a one-piece sealing gasket according to any preceding claim, the first sealing member being positioned to seal between the first end plate and the first end of the first and second stator sections, the second sealing member being positioned to seal between the second end plate and the second end of the first and second stator sections, the first longitudinal sealing member being positioned between the first and second stator sections within a groove defined in the first stator section to seal along the pumping chamber and between the first and second stator sections, the second longitudinal sealing member being positioned between the first and second stator sections within another groove defined in the first stator section to seal along the pumping chamber and between the first and second stator sections.

[0036] In some embodiments, the pumping mechanism comprises multiple stages arranged longitudinally within the first and the second stator sections, and the plurality of protrusions are longitudinally staggered to inhibit leakage between two or more of the multiple stages. In this way, the protrusions inhibit interstage leakage.

[0037] In some embodiments, the width of the first and second longitudinal sealing members is less than the width of the groove and the another groove, respectively. A typical longitudinal sealing member (without the protrusions) is designed to be approximately the same width as the groove for receiving the sealing member such that it fits tightly within the groove. In contrast, embodiments provide longitudinal sealing members which are narrower than the grooves for receiving them which allows space for thermal expansion. In this way, changes in temperature are less likely to affect the integrity of the seal. Only with the additional width provided by the protrusions are the longitudinal sealing members capable of sealing against the side walls of the groove. It follows that, in some embodiments, the width of the first and second longitudinal sealing members together with the protrusions is substantially the same as or larger than the width of the grooves.

[0038] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0039] Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which:

[0042] Figure 1 shows a portion of a vacuum pump according to an embodiment;

[0043] Figure 2 shows a sealing gasket according to an embodiment;

[0044] Figure 3 shows a portion of the sealing gasket of Figure 2;

[0045] Figure 4 illustrates the transformation of the sealing gasket of Figure 2 from a two dimensional to a three dimensional gasket capable of sealing across multiple planes inside a vacuum pump;

[0046] Figure 5 shows a poka-yoke formation of the sealing gasket of Figure 2; and Figure 6 shows the arrangement of a sealing gasket within a groove according to some embodiments.

[0047] DESCRIPTION OF THE EMBODIMENTS

[0048] Before discussing the embodiments in any more detail, first an overview will be provided. Embodiments provide a three-dimensional sealing gasket which is manufactured in a two-dimensional state for sealing a body split in multiple planes such as a vacuum pump. The gasket may seal sections of the vacuum pump having different pressures and also seal the inside of the vacuum pump from the external environment.

[0049] The gasket comprises two sealing members or pieces forming a closed shape, such as an 0-ring, connected with at least two longitudinal sealing members or linear bar-shaped sealing pieces. The design of the gasket is optimised to be made by one parting line injection moulding. The three-dimensional shape is formed when the gasket is inserted into the vacuum pump to be sealed. In this process, the closed shape pieces are twisted into a second plane different from a first plane defined by the longitudinal sealing members. The closed shape pieces may have a circular cross-section such that, when they are twisted, the shape of the gasket remains substantially unaffected. However, it will be appreciated that each sealing member may have a circular or polygonal cross section. A poka- yoke locking feature may be provided on one of the sealing members to help ensure correct placement of the gasket within the vacuum pump.

[0050] Embodiments provide protrusions which are staggered on alternating sides of the longitudinal sealing members which are configured to force the longitudinal sealing members into a snake-like shape when in-situ within a groove of the vacuum pump. The bent longitudinal sealing members provide a spring-like function and bias the protrusions into the side surfaces of the grooves to form seals against both side surfaces of the groove. In this way, embodiments may increase pressure on the sealing surfaces and inhibit leakage along the groove. Moreover, embodiments may allow for some flexibility in the groove shape, i.e. , the gasket may be suitable for grooves which are not exact matches to the gasket shape and thickness. This may allow for backwards compatibility with a variety of vacuum pumps. Furthermore, by providing the protrusions on the side of the longitudinal sealing members, existing moulding dies may be easily modified and manufacture may be simple. In some embodiments, the longitudinal sealing members are narrower than the grooves for receiving the sealing members and the protrusions are staggered and not opposite each other which may allow space for thermal expansion of the gasket within the grooves.

[0051] Figure 1 shows a portion of a vacuum pump 1 according to an embodiment. The vacuum pump 1 comprises a first and a second stator section 2 and a first and a second end plate 3. In Figure 1 , the second end plate and the second stator section have been omitted for clarity. The stator sections 2 define the pumping chamber of the vacuum pump 1 and house the pumping mechanism of the vacuum pump 1 , the pumping mechanism being configured to pump gas from an inlet to an outlet of the vacuum pump 1 . The end plates 3 are mounted to either end of the stater sections 2 and are configured to retain the pumping mechanism within the stator sections 2. A one-piece gasket 10 is positioned within the vacuum pump 1 to inhibit gas leakage between the vacuum chamber and the environment outside the vacuum pump as well as between stages of the vacuum pump in case of a multiple stage vacuum pump.

[0052] Figure 2 shows a one-piece sealing gasket 10 according to an embodiment. The gasket 10 comprises a first and a second sealing member 11a, b for sealing between respective ends of the first and second stator sections 2 and the first and second end plates 3 of the vacuum pump 1 , respectively. Each sealing member 11a, b defines a closed shape, in this case, a rounded rectangle but it may be an annulus or other closed shape depending on the configuration of the vacuum pump. Furthermore, the closed shape may change when the gasket is inserted into the vacuum pump. The gasket 10 further comprises a first and a second longitudinal sealing member 12a, b interconnecting the first and second sealing members 11a, b for sealing along and between the first and second stator sections 2. The first and second longitudinal members 12a, b connect at opposite sides to the outside of the closed shape defined by the first and second sealing members 11a, b. The gasket 10 further comprises a plurality of protrusions 13 which are longitudinally staggered along the length of the longitudinal sealing members 12a, b. The protrusions 13 extend from alternating sides of the longitudinal sealing members 12a, b and are longitudinally spaced such that they do not overlap in the longitudinal direction. The protrusions 13 are configured to engage the side walls of the grooves 4 defined within the first stator section 2 to deform the longitudinal sealing members 12a, b into a tortuous or snake-like path within the groove 4. The urge for the longitudinal sealing members 12a, b to return to a straight state biases the protrusions into the side walls of the groove 4 to form a seal. In this embodiment, the gasket 10 comprises five protrusions 13 on each longitudinal sealing member 12a, b. However, it will be appreciated that more than five or fewer than five protrusions may be used. For example, in some embodiments, the gasket 10 comprises only the three central protrusions of the five protrusions shown on each longitudinal sealing member 12a, b.

[0053] The first and second sealing members 11a, b have a circular cross-section and the first and second longitudinal members 12a, b have a rectangular crosssection (shown best in Figure 3). The protrusions 13 extend from side surfaces of the longitudinal sealing members 12a, b such that the protrusions 13 extend perpendicularly to the longitudinal direction defined by the respective longitudinal sealing member. It will be appreciated that other cross-sections may be used for either the sealing members 11a, b or the longitudinal sealing members 12a, b. In some embodiments, these components have the same cross-section shape.

[0054] The protrusions 13 form a semi-circular shape to help ensure a consistent surface area is engaging the side walls of the grooves regardless of the contact angle. This shape further helps to distribute the force from engaging the side wall evenly to the longitudinal sealing members 12a, b.

[0055] It will be appreciated that the drawings may not be to scale and that the dimensions (e.g., the length and width) of each of the components of the gasket 10 may vary. For example, the longitudinal sealing members 12a, b may be longer relative to the other components than what is shown.

[0056] Figure 4 shows how the gasket 10 is configured to deform from an initial planar or two-dimensional state (top of Figure 4) in which the gasket 10 is manufactured to a three-dimensional state (bottom of Figure 4) for use inside the vacuum pump 1 . In the initial planar state, the first and second sealing members 11a, b and the first and second longitudinal sealing members 12a, b are in a first plane, the first plane being defined by the two longitudinal sealing members 12a, b. In the second three-dimensional state, the first and second sealing members 11a, b are twisted relative to the first and second longitudinal sealing members 12a, b such that they define a second plane which is substantially perpendicular to the first plane defined by the longitudinal sealing members 12a,b. In this way, the longitudinal sealing members 12a, b can be orientated appropriately for sealing between the stator sections 2 whilst the sealing members 11a, b can be orientated appropriately to seal between the end plates 3 and the ends of the stator sections 2. Note that the seal created by the sealing members 11a, b is not significantly affected by the twisting motion experienced when deforming from one state to the other because the sealing members 11a, b have a circular cross section which is rotationally symmetric at all angles.

[0057] In some embodiments, the gasket may be formed from an elastomer such that the gasket is deformable between the initial planar and the three-dimensional state and such that the longitudinal sealing members 12a, b can deform to adopt the tortuous snake-like path within the groove 4 of the vacuum pump 1 . It will be appreciated that the gasket 1 may be formed from other materials which permit such deformation. In some embodiments, the gasket is a moulded gasket. However, other methods of manufacture may be used.

[0058] Figure 5 shows that the gasket 10 comprises a poka-yoke formation 14 for engaging a corresponding recess defined in the vacuum pump to aid positioning of the sealing gasket 10 within the vacuum pump 1 . It will be appreciated that a poka-yoke formation 14 may be formed on one or more of the following: the first sealing member 11a, the second sealing member 11b, the first longitudinal sealing member 12a, the second longitudinal sealing member 12b. The recess for receiving the poka-yoke formation may be formed on either of the stator sections 2 or end plates 3 as appropriate. In some embodiments, the sealing gasket does not include a poka-yoke feature.

[0059] Figure 6 shows embodiments of a longitudinal sealing member 12 positioned within the groove 4 of a stator section 2 of a vacuum pump 1 . In the embodiment on the right-hand side, the longitudinal sealing member 12 comprises three protrusions which engage the side walls 5 of the groove 4. In this way, each protrusion 13 is configured to push the portion of the longitudinal sealing member 13 from it extends away from the side wall 5. As the protrusions 13 are longitudinally staggered on alternating sides of the longitudinal sealing member 12, the longitudinal sealing member 12 is forced into a tortuous or snake-like path within the groove 4. The urge for the longitudinal sealing member 12 to straighten creates a spring-like force on the protrusions 13 biasing them into the side walls 15 to form a seal which inhibits gas flow along the length of the longitudinal sealing member 12. Figure 6 further shows that the width, W, of the longitudinal sealing member 12, specifically the areas of the longitudinal sealing member 12 without a protrusion, is less than the width of the respective groove 4 in which it is received. In this way, space 15 is created within the groove to allow for thermal expansion which means that changes in temperature are less likely to affect the integrity of the seal.

[0060] In the embodiment on the left-hand side of Figure 6, the longitudinal sealing member 12 comprises five protrusions. It will be appreciated that two or more protrusions 13 may be used on each longitudinal sealing member 12 to force the longitudinal sealing member 12 into a tortuous path. However, by increasing the number of protrusions 13, for example, from three to five, minor gas leaks along the length of the groove can be reduced or eliminated. This may be advantageous where the groove comprises curved corners or chamfered edges which can be tricky to seal against.

[0061] As shown at the top of Figure 6, the protrusions 13 are evenly distributed about the centre of the longitudinal sealing members 12. In some embodiments, the protrusions 13 are positioned such that the protrusions 13 of the gasket 10 form seals across at least two stages of a multi-stage vacuum pump. It will be appreciated that the protrusions 13 may not be centred on the longitudinal sealing members 12 and may be positioned to one side depending on the configuration of the vacuum pump.

[0062] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0063] REFERENCE SIGNS

[0064] 1 Vacuum Pump

[0065] 2 Stator section

[0066] 3 End plate 4 Groove

[0067] 5 Side Walls

[0068] 10 Sealing gasket

[0069] 11 Sealing member (closed shape)

[0070] 12 Longitudinal sealing member 13 Protrusions

[0071] 14 Poka-yoke formation

[0072] 15 Space

Claims

CLAIMS1 . A one-piece sealing gasket for sealing in multiple planes in a vacuum pump, the sealing gasket comprising: a first sealing member defining a closed shape; a second sealing member defining a closed shape; a first longitudinal sealing member interconnecting the first and the second sealing member; and a second longitudinal sealing member interconnecting the first and the second sealing member, the first and second longitudinal sealing members each comprising a plurality of longitudinally staggered protrusions extending perpendicularly to a longitudinal direction defined by the respective longitudinal sealing member, and when the first and second longitudinal sealing members are received within a respective groove of the vacuum pump, each of the plurality of protrusions is configured to engage a side wall of the respective groove such that the first and second longitudinal sealing members are deformed to adopt a tortuous path within the respective groove.

2. A sealing gasket according to claim 1 , wherein the sealing gasket is configured to deform from an initial planar state in which the first and second sealing members and the first and second longitudinal sealing members are in a first plane defined by the first and second longitudinal sealing members to a three-dimensional state in which the first and second sealing members are twisted with respect to the first and second longitudinal sealing members to define a second plane that is different to the first plane.

3. A sealing gasket according to claim 2, wherein the second plane is substantially perpendicular to the first plane.

4. A sealing gasket according to any preceding claim, wherein the plurality of protrusions extend from alternate sides of the first and second longitudinal sealing members.

5. A sealing gasket according to any preceding claim, wherein the plurality of protrusions comprises at least three protrusions.

6. A sealing gasket according to any preceding claim, wherein the plurality of protrusions comprises at least five protrusions.

7. A sealing gasket according to any preceding claim, wherein the plurality of protrusions are staggered such that the protrusions do not overlap in the longitudinal direction.

8. A sealing gasket according to any preceding claim, wherein the first and second longitudinal sealing members are configured to bias the plurality of protrusions against the side wall of the respective grooves to form a seal.

9. A sealing gasket according to any preceding claim, wherein the plurality of protrusions have a semi-circular cross-section.

10. A sealing gasket according to any preceding claim, wherein the first and the second longitudinal sealing members have a rectangular cross-section, and the plurality of protrusions extend from side surfaces of the first and second longitudinal sealing members.

11. A sealing gasket according to any preceding claim, wherein the first and second longitudinal sealing members are for sealing along and between a first and a second stator section of the vacuum pump.

12. A sealing gasket according to any preceding claim, wherein the plurality of protrusions are evenly distributed about an approximate centre of the first and second longitudinal sealing members.

13. A vacuum pump comprising: a first stator section; a second stator section mounted to the first stator section such that the first and second stator sections together define a pumping chamber housing a pumping mechanism of the vacuum pump, the pumping mechanism being configured to pump gas from an inlet to an outlet of the vacuum pump; a first end plate mounted to a first end of the first and second stator sections; a second end plate mounted to a second end of the first and second stator sections, the first and second end plates being configured to retain the pumping mechanism within the pumping chamber; and a one-piece sealing gasket according to any preceding claim, the first sealing member being positioned to seal between the first end plate and the first end of the first and second stator sections, the second sealing member being positioned to seal between the second end plate and the second end of the first and second stator sections, the first longitudinal sealing member being positioned between the first and second stator sections within a groove defined in the first stator section to seal along the pumping chamber and between the first and second stator sections, the second longitudinal sealing member being positioned between the first and second stator sections within another groove defined in the first stator section to seal along the pumping chamber and between the first and second stator sections.

14. A vacuum pump according to claim 13, wherein the pumping mechanism comprises multiple stages arranged longitudinally within the first and the second stator sections, and the plurality of protrusions are longitudinally staggered to inhibit leakage between two or more of the multiple stages.

15. A vacuum pump according to claim 13 or claim 14, wherein the width of the first and second longitudinal sealing members is less than the width of the groove and the another groove, respectively.

Images