Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/021—Sealings between relatively-stationary surfaces with elastic packing
  • F16J15/022—Sealings between relatively-stationary surfaces with elastic packing characterised by structure or material
  • F16J15/024—Sealings between relatively-stationary surfaces with elastic packing characterised by structure or material the packing being locally weakened in order to increase elasticity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
  • F04C27/001—Radial sealings for working fluid
  • F04C27/003—Radial sealings for working fluid of resilient material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
  • F04C27/02—Liquid sealing for high-vacuum pumps or for compressors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/021—Sealings between relatively-stationary surfaces with elastic packing
  • F16J15/022—Sealings between relatively-stationary surfaces with elastic packing characterised by structure or material
  • F16J15/024—Sealings between relatively-stationary surfaces with elastic packing characterised by structure or material the packing being locally weakened in order to increase elasticity
  • F16J15/027—Sealings between relatively-stationary surfaces with elastic packing characterised by structure or material the packing being locally weakened in order to increase elasticity and with a hollow profile
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
  • F16J15/08—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing
  • F16J15/0887—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with exclusively metal packing the sealing effect being obtained by elastic deformation of the packing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/02—Sealings between relatively-stationary surfaces
  • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
  • F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
  • F16J15/104—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing characterised by structure

Definitions

• the field of the invention relates to seals, vacuum systems having such seals and a method of manufacturing the seals.
• An effective seal is one which is resilient and can deform to fill a gap. Seals have often been manufactured using elastomer materials which are both resilient and deformable.
• Elastomer seals may not be sufficiently resistant to either high temperatures or aggressive materials to function as effective seals in such systems.
• Metal seals are known. A drawback of metal seals is that for them to seal effectively they require both a high clamping force and a fine finish on the surfaces that they seek to seal between. Higher clamping forces can lead to distortion of the components being clamped and may require specialist clamping components and tools to undo and tighten the clamping components. Finer finishing of surfaces is expensive.
• a first aspect provides a longitudinal seal having a cross section comprising a wall around an inner section; wherein said wall is formed of a material which is configured such that a physical characteristic of said material varies by at least 10% along at least one of a length and said cross section of said seal, said variation in said physical characteristic causing a variation in at least one of a deformability and a resilience of a corresponding portion of said seal.
• the degree of deformability and the degree of resilience of a seal affects its sealing properties.
• the inventors of the present invention recognised, that both resilience and deformability depend on the physical characteristics of the material forming the seal and that changing these characteristics at different portions of the seal may allow the seal to function more effectively. Physical characteristics include density, and width of the wall of the seal.
• Changing the physical characteristics along the length or cross section of the seal changes its sealing properties and these can be selected to improve the sealing effectiveness of the seal. For example, the deformability of a section that is configured to mate with a surface to be sealed may be increased and the resilience of this section may be correspondingly reduced. However, the overall resilience of the seal may be maintained by increasing the resilience of another portion of the seal, where perhaps the deformability is less important. In this way the characteristics of a seal formed of a material that is not as resilient or deformable as an elastomer can be tuned to increase the effectiveness of the seal. This allows an effective seal to be made of a material with lower elasticity, such a material may have increased resistance to higher temperatures and aggressive chemicals.
• a longitudinal seal is an elongated seal that is longer than it is wide.
• the length is the distance along the wall of the seal and the width is the distance across the cross section.
• the seal may be a loop where the length is the circumference of the loop.
• the sealing surface is on the outer circumference of the wall.
• said at least one physical characteristic comprises a thickness of said wall.
• Varying the thickness of the wall that is the dimension of the wall in the cross section of the seal, varies the resilience and deformability of the seal; a thicker wall providing higher resilience and a thinner wall providing more deformability.
• the recognition of the effect that changes in the thickness of the wall has on the properties allows the seal to be designed and configured with increased deformability where that is appropriate, this being compensated for with increased resilience at other points where the deformability is not as important.
• said thickness of said wall varies along a length of said seal.
• the thickness of the wall may vary along the length of the seal and may in some embodiments and in some places along the seal fall as low as 0.01 mm and rise in others to higher values perhaps up to 0.5mm. In any case the variation along the length will be at least 10% and in some embodiments at least 50% and in others at least a 100%.
• said seal is configured to seal surfaces in a vacuum system and said wall is configured to be thinner at portions along the length of said seal that are remote from clamping elements for clamping said seal between said surfaces, such that a resilience of said seal away from said clamping elements is reduced.
• Varying the thickness of the wall along the length of the seal allows the seal to be configured such that it has greater resilience at the points where when in use the seal will be clamped. At these clamping points there is greater force on the seal and thus, greater resilience at these points allows the seal to maintain a more uniform cross section and a more uniform sealing effect along the length of the seal. In effect, it allows the resilience of the seal away from the clamping elements to be reduced and allows for reduced clamping forces and more effective sealing.
• said thickness of said wall varies around said cross section of said seal.
• the thickness of the wall may vary around the cross section of the seal. For example, it may be lower at and adjacent to a sealing surface of the seal.
• seals are configured with outer peripheral surfaces which have sealing surfaces thereon. These portions of the outer surface being the portions which act to provide the seal. It is advantageous if these sealing surfaces have a high deformability and thus, it may be
• Having a higher thickness at other points provides for a more resilient and robust seal while allowing it to be deformable at the points where it seals.
• said at least one physical characteristic comprises a density of said material forming said wall.
• Another physical characteristic which effects the resilience and deformability of a seal is the density of the material forming the wall of that seal. Variations in this density may allow the properties of the seal to be varied and thus, the seal to be tuned to its particular use.
• the density of said material at a sealing portion of an outer periphery of said seal is lower than a density of said material at an inner edge of said seal.
• a lower density material at the sealing outer surface of the seal allows the seal to be more deformable and provide a more effective seal.
• An increased density away from this portion provides a more resilient seal.
• a portion of said wall at and adjacent to said sealing portion comprises a porous or cellular portion. In some embodiments, this may be an additional protrusion extending from the outer wall. This protrusion may also be used to help locate the seal in a desired position.
• One way of reducing the density of the material and provide a more deformable surface is to change the structure at and adjacent to the sealing face such that it will collapse and conform to the mating surface.
• a porous or cellular structure will provide these properties.
• the density of said material forming said wall varies along a length of said seal.
• the density of the material forming the wall may also vary along a length of the seal. Where the wall is formed of a porous or cellular substance this change in density may be achieved by changing the porosity along the length of the wall.
• the density of said material forming said wall is lower at a portion of said seal that is remote from clamping elements for clamping said seal between said surfaces, such that a resilience of said seal away from said clamping elements is reduced.
• a more uniform compressed cross section of seal may be achieved by varying the density in this way along with a reduction in the required clamping forces.
• said wall around said inner portion comprises a portion having a substantially uniform cross section and a portion having a spring-like configuration.
• One way of providing differences in the properties of the seal around the cross section is to have a portion with a uniform section and a portion having a spring like configuration.
• the spring like configuration will provide elasticity and resilience while the uniform portion will provide an effective sealing surface.
• said portion having a spring like configuration comprises connecting portions angled to and connecting said portions with a uniform cross section, said connecting portions having gaps between them.
• the configuration of the spring-like portion may change along the length of the seal, such that the gap between, or the thickness of, the connecting portions may change to vary the resilience of the seal along its length.
• the seal may have a number of shapes, in some embodiments said wall and inner portion have a circular cross section.
• the wall may only extend around a portion of the inner portion at least for some of the length of the seal, in some embodiments the wall encloses the inner portion.
• said wall extends in a longitudinal direction and has a tubular shape. In some embodiments said wall extends longitudinally to form a loop.
• said material forming said wall of said seal is a non- elastomer material.
• a seal configured to provide varying resilience and deformability allows an effective seal to be formed of a material that is not an elastomer.
• Elastomers have high elasticity and generally form good seals but may not be resilient to high temperatures or aggressive chemicals.
• forming a seal of a material that is not an elastomer allows a material to be selected with appropriate properties for higher temperature and aggressive chemicals and where the configuration is according to an embodiment such a seal can still provide effective sealing.
• said material comprises a metallic material.
• said metallic material comprises at least one of
• aluminium an aluminium alloy, nickel, a nickel alloy, a precious metal, steel, stainless steel, copper.
• said material comprise a polymeric material comprising one or more thermoplastics.
• said polymeric material comprises at least one of a fluoropolymer, polyether ether ketone (PEEK) and polyphenylene sulphide (PPS).
• PEEK polyether ether ketone
• PPS polyphenylene sulphide
• the seal may be formed entirely of a metal or entirely of a polymeric material, in some embodiments it may be formed of a combination of both of these materials.
• said inner portion comprises a void. ln other embodiments, said inner portion comprises a substance for increasing a resilience of said seal.
• the inventors of the present invention recognised that an outer periphery with increased deformability but reduced resilience could be used for a seal where an internal structure was provided within the outer periphery to improve the resilience.
• the wall thickness for example could be reduced making it more deformable and providing a better sealing surface. Thicknesses as low as 0.01 mm might be acceptable in such circumstances.
• said substance comprises a continuous solid structure attached to said wall.
• said continuous solid structure is non- uniform along a length of said seal such that a resilience of said seal changes along said length.
• the structure inside the seal may be made non uniform along the length of the seal.
• the continuous solid structure may have a number of forms, in some embodiments it comprises at least one internal wall extending across the inner section.
• said at least one internal wall extends across a diameter of said inner portion.
• said substance comprises a porous or cellular material.
• a porous or cellular material that is one with voids, allows it to be compressed, and yet provides resilience.
• said seal is configured to mate with surfaces to be sealed and said density of said porous material remote from clamping elements for clamping said seal between said surfaces is reduced, such that a resilience of said seal away from said clamping elements is reduced.
• Changes in the density of the interior substance can be used to change the resilience of the seal. Where the seal is used in conjunction with clamping elements to hold the seal it may be advantageous to increase the resilience at points adjacent to the clamping elements and have reduced resilience at other points.
• a second aspect of the present invention provides a vacuum system comprising a least one seal according to a first aspect of the present invention.
• the vacuum system comprises at least one seal configured with portions that have reduced resilience either through the reduced thickness of the wall and/or the reduced resilience of the internal structure, the vacuum system having clamping elements to hold at least one seal between two co-operating surfaces at portions of the seal with increased resilience.
• a third aspect of the present invention provides a method of manufacturing of a seal according to any preceding claim using additive manufacturing techniques.
• seals made for example of metal are made forming metal tubes or other profiles and joining them by welding. It is difficult to control the Young’s modulus and other mechanical properties of the seal element made by these traditional methods.
• the use of an additive manufacturing techniques allows the mechanical properties to be varied both in the cross section of the seal and also around the perimeter of a seal and along its length. This allows seals to be designed with variations in these properties appropriate to their environment allowing lower elasticity material to provide effective seals. This may allow vacuum system to use lower clamping forces and still provide high seal integrity.
• the additive manufacturing technique is selected from stereo lithography (SLA), fused deposition modelling (FDM), multi-jet modelling (MJM), 3D printing and selective laser sintering (SLS).
• Figure 1 shows a cross section of a seal having a variable wall thickness according to a first embodiment
• Figure 2 shows a longitudinal section of a seal having a variable wall thickness along a length of the seal according to a second embodiment
• Figure 3 schematically shows a cross section of a seal having a variable density across the cross section according to a third embodiment
• Figure 4 schematically shows a cross section of a seal having a variable density across the cross section according to a further embodiment
• Figure 5 shows a cross section of a seal having an internal structure to increase resilience
• Figure 6 shows a longitudinal section of a seal having an internal structure with variable density along a length of the seal
• Figure 7 shows a longitudinal section of a seal having a spring like configuration for a section of the outer wall
• Figure 8 shows a cross section of the seal of Figure 7.
• seals allow seals to be manufactured with targeted variations in elasticity that allow the sealing force to be optimised for seal effectiveness against the clamping force.
• profile, shape and constituent material of the seal can be designed to provide a desired seal integrity with a reduced clamping force.
• Owing to this ability to fine tune the design of the seal it may be made of materials with reduced elastic properties such as metal. Such materials may have improved heat and chemical resistance.
• a change in structure or density at the sealing face for example the provision of an open structure such as foam that will collapse and conform to the mating surface.
• additional features may be added such as features that locate or align the seal to the sealing face and a coating on the sealing face to enhance the seal integrity.
• Figure 1 shows a cross section of a seal according to an embodiment wherein the outer wall 10 that encloses the inner section has a variable wall thickness.
• the thicker portions Providing variations in the wall thickness allows portions of the wall, the thicker portions, to provide increased resilience while the thinner portions have increased deformability.
• the portions with increased deformability provide a more effective sealing surface as they are easier to deform.
• the sealing areas of the seal that are areas of the outer surface that when the seal is mounted in use in a vacuum system provide the sealing effect are configured to have a thinner wall than other portions remote from these sealing portions. In this way, the effective sealing portion is more deformable while the overall seal retains it resilience owing to the thicker portions.
• Figure 2 shows a longitudinal section through a second embodiment of a seal which in a similar way to the embodiment of Figure 1 has a varying thickness of the outer wall 10.
• variation in thickness occurs along the length of the seal.
• variation may occur both across the cross section and/or around the perimeter and/or along the length of the seal.
• the thicker portions of the seal are configured to be located within a vacuum system adjacent to clamping elements such that the clamping forces 20 act on the more resilient parts of the seal and the portions of the seal that are remote from the clamping elements and have reduced clamping forces acting on them are formed with thinner walls and have lower resilience but greater deformability.
• a seal that is adapted to its use and allows the sealing force to be optimized or at least improved for seal effectiveness against the clamping force is provided.
• Figure 3 shows an alternative embodiment where the physical characteristics that are used to adapt the seal to the forces that act on it during use are the density of the material, the density of the material forming the outer wall 10 changing.
• the density may change across the cross section of the seal and/or it may change along the length of the seal.
• reduced density portions with lower resilience are provided and increased density portions with high resilience are provided.
• the reduced resilience portions may be provided towards the sealing surfaces around the perimeter while the increased density portions may be provided remote from these portions and at longitudinal positions
• Figure 4 shows a further embodiment where the outer wall is provided with additional regions 12 that protrude from the wall and where the material is porous and thus a particularly low density. These are provided at the sealing surfaces of the seal and will compress and conform to the mating surfaces. They may also act to locate the seal in a certain orientation within the vacuum system.
• Figure 5 shows the cross section of a further embodiment where an internal structure is provided within the outer wall 10.
• internal walls 22 are provided which cross the inner section of the seal and provide resilience to deformation of the seal.
• the addition of such an internal structure allows the outer wall to be made thinner than is the case where there is no internal structure. This has the advantage of providing an improved deformability of the outer structure which may provide improved sealing and allow the seal to provide effective sealing in a vacuum system with a sealing surface finish that is not as fine.
• the internal structure is provided by internal walls extending and attached to the outer wall 10
• the internal structure may be different and may for example be formed of a porous material.
• This porous material may have a differing density across its cross section and may also have a differing density along its length thereby providing targeted changes in the resilience of the seal at different points.
• the seal of figure 5 may have variations in the width of the inner walls 22 along its length to provide differences in resilience.
• density of the internal substance the wall may also be formed of a porous substance the porosity of the wall may also vary along its length.
• Figure 6 shows a longitudinal cross section through a seal with a porous interior 24 in which the density of the porous interior changes along the length of the seal allowing for the seal to be arranged such that areas of increased density and increased resilience are proximate to clamping elements and areas with reduced density and reduced resilience are remote from these elements when mounted in the vacuum assembly. This allows the seal to be held in place with reduced clamping forces without unduly affecting the sealing properties of the seal.
• Figure 7 shows a side view of a further embodiment where a portion of the perimeter of the seal is formed of strips 30 of the material forming the outer wall 10. This provides a spring like construction and increases the resilience of the seal.
• Figure 8 shows a cross section of such a seal. It should be noted that the number, thickness and gaps between the strips can be varied along the length of the seal to increase or decrease the resilience of the seal at different parts as required.
• the seals are shown in cross section, longitudinal section or as a side view.
• tubular form may be a loop adapted to seal between stators of a vacuum pump for example, or around connecting elements in a vacuum system. Owing to the ability not to use elastomer materials for these seals they are particularly effective for use in abatement systems where aggressive materials may be being pumped and high temperature used.
• seals allow them to be made of metal for example and yet have properties that can be varied along the length and/ or around the perimeter and/ or across the cross section. This allows the seals to be adapted to particular positions and particular clamping forces and improves sealing effectiveness.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Gasket Seals (AREA)
• Adhesives Or Adhesive Processes (AREA)

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Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (3)

Citations (4)

Family Cites Families (1)

• 2018
  • 2018-09-05 GB GB1814455.0A patent/GB2576896B/en active Active
• 2019
  • 2019-09-04 DE DE212019000370.2U patent/DE212019000370U1/de active Active
  • 2019-09-04 WO PCT/GB2019/052463 patent/WO2020049295A1/en active Application Filing
  • 2019-09-04 JP JP2021600037U patent/JP3233724U/ja active Active
  • 2019-09-04 KR KR2020217000017U patent/KR20210001093U/ko not_active Application Discontinuation
  • 2019-09-04 CN CN201990001003.3U patent/CN216555325U/zh active Active
  • 2019-09-05 TW TW108132126A patent/TW202023837A/zh unknown
  • 2019-09-05 TW TW111209270U patent/TWM640001U/zh unknown

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