EP4638966A1 - Seal for scroll pump - Google Patents

Seal for scroll pump

Info

Publication number
EP4638966A1
EP4638966A1 EP23828240.4A EP23828240A EP4638966A1 EP 4638966 A1 EP4638966 A1 EP 4638966A1 EP 23828240 A EP23828240 A EP 23828240A EP 4638966 A1 EP4638966 A1 EP 4638966A1
Authority
EP
European Patent Office
Prior art keywords
channel seal
inner portion
outer portion
scroll pump
scroll
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23828240.4A
Other languages
German (de)
French (fr)
Inventor
Christopher Miles
Andrew James Seeley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Edwards Ltd
Original Assignee
Edwards Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Edwards Ltd filed Critical Edwards Ltd
Publication of EP4638966A1 publication Critical patent/EP4638966A1/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
    • 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
    • F04C27/005—Axial sealings for working fluid
    • F04C27/006—Elements specially adapted for sealing of the lateral faces of intermeshing-engagement type pumps, e.g. gear pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C1/00—Rotary-piston machines or engines
    • F01C1/02—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F01C1/0207—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
    • F01C1/0215—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
    • F01C1/0223—Rotary-piston machines or engines of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving with symmetrical double wraps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C19/00—Sealing arrangements in rotary-piston machines or engines
    • F01C19/08—Axially-movable sealings for working fluids
    • 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
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
    • F04C18/0215—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
    • F04C18/0223—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving with symmetrical double wraps
    • 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
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
    • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
    • F04C18/0246—Details concerning the involute wraps or their base, e.g. geometry
    • F04C18/0253—Details concerning the base
    • 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
    • F04C27/005—Axial sealings for working fluid

Definitions

  • the present invention relates to scroll pumps.
  • Scroll pumps are a known type of pump used in various different industries to pump fluid.
  • Scroll pumps operate by using the relative motion of two intermeshed scrolls (known as a fixed scroll and an orbiting scroll) to pump fluid.
  • Each of the fixed and orbiting scrolls includes a spiral wall extending from a base.
  • Scroll pumps include seals to prevent leakage of fluid from various parts of the scroll pump.
  • a channel seal for a scroll pump comprising an inner portion and an outer portion located around the periphery of the inner portion.
  • the outer portion is formed from a more wear resistant material than the inner portion.
  • a surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump.
  • the channel seal may further comprise a sacrificial bedding-in layer disposed on the outer portion.
  • the sacrificial bedding-in layer may be integrally formed with the inner portion.
  • the axial offset may be equal to a thickness of the sacrificial bedding-in layer.
  • the inner portion may be formed from a different type of material to the outer portion.
  • the outer portion may be formed from a harder material than the inner portion.
  • the sacrificial bedding-in layer may be formed from the same material as the inner portion.
  • the channel seal may further comprise a base portion.
  • the base portion and the outer portion may together define a cavity within which the inner portion is located.
  • the base portion may be integrally formed with the outer portion.
  • the base portion may be formed from the same type of material as the outer portion.
  • the inner portion may be veneer bonded to the base portion and the outer portion.
  • the inner portion may be formed as a coating on the base portion and the outer portion.
  • the inner portion may comprise a spiral aperture.
  • a scroll pump comprising the channel seal of the above aspect.
  • a method of manufacturing a channel seal for a scroll pump comprises forming an inner portion, and forming an outer portion around the periphery of the inner portion such that a surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump, wherein the outer portion is formed from a more wear resistant material than the inner portion.
  • Figure 1 is a schematic illustration (not to scale) showing a cross-sectional view of a scroll pump
  • Figure 2 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal for the scroll pump;
  • Figure 3 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of another channel seal for the scroll pump.
  • Figure 1 is a schematic illustration (not to scale) showing a cross-sectional view of a scroll pump 100.
  • the scroll pump 100 comprises housing portions 110, a fixed scroll 120, an orbiting scroll 130, a drive shaft 140, an actuator 150, a bearing assembly 160, a first channel seal 170, and a second channel seal 180.
  • the housing portions 110 and the fixed scroll 120 together define an overall housing of the scroll pump 100 within which other components of the scroll pump 100 are located.
  • the fixed scroll 120 may not define any of the overall housing of the scroll pump 100 and instead may be located entirely within an overall housing.
  • the orbiting scroll 130 is located within the overall housing of the scroll pump 100.
  • the orbiting scroll 130 is intermeshed with the fixed scroll 120 to define a space (or channel) which is used by the scroll pump 100 during operation to pump fluid (e.g. a gas).
  • the orbiting scroll 130 is configured to orbit relative to the fixed scroll 120 to pump fluid from an inlet (not shown) of the scroll pump 100 to an outlet (not shown) of the scroll pump 100.
  • the precise physical mechanism by which fluid is pumped by the orbiting of the orbiting scroll 130 relative to the fixed scroll 120 is well understood and will not be described herein for the sake of brevity.
  • the fixed scroll 120 comprises a first base 122 and a first spiral wall 124.
  • the orbiting scroll 130 comprises a second base 132 and a second spiral wall 134.
  • the first spiral wall 124 and second spiral wall 134 are intermeshed with each other.
  • the first spiral wall 124 extends perpendicularly from the first base 122 towards the second base 132 such that an end surface (also known as the tip) of the first spiral wall 124 is proximate to but not in contact with an opposing surface of the second base 132.
  • the second spiral wall 134 extends perpendicularly from the second base 132 towards the first base 122 such that an end surface (or tip) of the second spiral wall 134 is proximate to but not in contact with an opposing surface of the first base 122.
  • the first channel seal 170 is sandwiched between the end surface of the second spiral wall 134 and the opposing surface of the first base 122.
  • the second channel seal 180 is sandwiched between the end surface of the first spiral wall 124 and the opposing surface of the second base 132.
  • the fixed scroll 120 and orbiting scroll 130 may be biased together by a biasing apparatus (not shown) of the scroll pump (e.g. one or more springs).
  • first base 122 and first spiral wall 124 are integrally formed with each other, and the second base 132 and second spiral wall 134 are integrally formed with each other.
  • one or both of the spiral walls 124, 134 are not integrally formed with their respective bases 122, 132.
  • the drive shaft 140 is coupled to the orbiting scroll 130 and configured to rotate to drive the orbiting of the orbiting scroll 130.
  • the drive shaft 140 is located within the overall housing of the scroll pump 100 and mounted via the bearing assembly 160 which facilitates rotation of the drive shaft 140.
  • the drive shaft 140 extends through both the fixed scroll 120 and the orbiting scroll 130 is mounted at an end of the draft shaft 140.
  • the actuator 150 (e.g. an electric motor) is coupled to the drive shaft 140 and configured to actuate the drive shaft 140 to cause the drive shaft 140 to rotate to drive the orbiting of the orbiting scroll 130.
  • the actuator 150 is located within the overall housing of the scroll pump 100 and mounted around the drive shaft 140.
  • the bearing assembly 160 mechanically couples the drive shaft 140 to the orbiting scroll 130 and the overall housing of the scroll pump 100 such that the drive shaft 140 is able to rotate within the scroll pump 100 to drive the orbiting scroll 130.
  • the first channel seal 170 and the second channel seal 180 provide axial seals to prevent/oppose leakage of fluid axially between different sections of the space (or channel) which is used by the scroll pump 100 during operation to pump fluid.
  • the end surface of the first spiral wall 124 rubs against the second channel seal 180 and the end surface of the second spiral wall 134 rubs against the first channel seal 170.
  • the first and second channel seals 170, 180 are subject to wear from the rubbing over their lifetime. Seal structures which may be used for the first and second channel seals 170, 180 will now be described with reference to Figure 2 and Figure 3.
  • Figure 2 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal 200 for the scroll pump 100 of Figure 1 according to an embodiment.
  • the channel seal 200 of Figure 2 may be used as the first channel seal 170 or the second channel seal 180 in the scroll pump 100 of Figure 1.
  • the channel seal 200 comprises an inner portion 210 and an outer portion 220 located around the periphery of the inner portion 210.
  • the channel seal 200 defines a radial direction and an axial direction, and the outer portion 220 is located radially outwards of the inner portion 210.
  • the outer portion 220 may be bonded to the inner portion 210. Alternatively, the outer portion 220 may be a separate piece to the inner portion 210 and not bonded or attached.
  • the channel seal 200 has an overall circular shape.
  • the inner portion 210 has a circular shape with a spiral aperture matching the shape of the spiral wall of the scroll onto which the channel seal 200 fits, and a circular aperture matching the shape of the part of the drive shaft of the scroll pump around which the channel seal 200 is placed.
  • the outer portion 220 has a ring shape.
  • the channel seal 200 and its inner and outer portions 210, 220 may have other different shapes, as long as the functions described herein are fulfilled.
  • the outer portion 220 is formed from a material which is more wear resistant than the inner portion 210.
  • the outer portion 220 may be formed from a harder material than the inner portion 210.
  • the outer portion 220 may be formed from a different type of material to the material from which the inner portion 210 is formed.
  • the inner portion 210 may be formed from Polytetrafluoroethylene (PTFE) with a certain filler and the outer portion 220 may be formed from PTFE with a different filler which makes the outer portion 220 more wear resistant.
  • PTFE Polytetrafluoroethylene
  • the inner portion 210 may be formed from PTFE with a certain filler and the outer portion 220 may be formed from PTFE with the same filler but at a different density which makes the outer portion 220 more wear resistant.
  • a more wear resistant material for the channel seal is a material which wears down at a lower rate when used in a given scroll pump (e.g. the scroll pump 100 of Figure 1) in a given set of operating conditions, compared to a less wear resistant material for the channel seal in that same given scroll pump in the same given set of operating conditions.
  • the inner portion 210 is thicker than the outer portion 220.
  • the channel seal 200 further comprises a sacrificial bedding-in layer 230 disposed on the outer portion 220.
  • the sacrificial bedding- in layer 230 is located radially outwards of the inner portion 210 and is layered onto the outer portion 220 in the axial direction.
  • the sacrificial bedding-in layer 230 has a thickness such that the thickness of the sacrificial bedding-in layer 230 added to the thickness of the outer portion 220 is substantially the same as the thickness of the inner portion 210.
  • the sacrificial bedding-in layer 230 covers a side of the outer portion 220 such that the exposed surface of the sacrificial bedding-in layer 230 is substantially flush with a surface of a side of the inner portion 210.
  • the sacrificial bedding-in layer 230 is integrally formed with the inner portion 210.
  • the inner portion 210 and the sacrificial bedding-in layer 230 together form a single piece of material.
  • the sacrificial bedding-in layer 230 is formed from the same material as the inner portion 210.
  • the above-described structure means that the surface of the inner portion 210 which is subject to wear during operation of the scroll pump is axially offset from the surface of the outer portion 220 which is subject to wear during operation of the scroll pump (after the sacrificial bedding-in layer 230 has been worn through).
  • the axial offset is equal to the thickness of the sacrificial bedding-in layer 230.
  • the channel seal 200 When the channel seal 200 is initially installed in a scroll pump and the scroll pump is operated, the channel seal 200 goes through a bedding-in phase in which the inner portion 210 and the sacrificial bedding-in layer 230 are worn down (at the same rate) until the part of the scroll pump wearing down the sacrificial bedding-in layer 230 wears completely through the sacrificial beddingin layer 230 and reaches the outer portion 220.
  • the more wear resistant outer portion 220 takes more load than the inner portion 210, and the wear rate is mostly determined by the outer portion 220.
  • the above described structure advantageously means that the channel seal 200 can be relatively quickly initially bedded-in on less wear resistant material (i.e. the material of the inner portion 210 and the sacrificial bedding-in layer 230), and then the more wear resistant material (i.e. the material of the outer portion 220) is subjected to the bulk of the load on the channel seal 200, thus providing longer overall service life for the channel seal 200.
  • the abovedescribed quick bedding-in tends to be desirable for scroll pumps because it tends to allow the scroll pump to reach full operational capacity quickly and with less run-time.
  • the above-described structure also tends to allow a manufacturer of the scroll pump to avoid the use of extra specialised bedding-in equipment. This in turn tends to reduce costs for the supplier.
  • the above-described bedding-in process also tends to help mitigate the effects of the seal being manufactured with imperfect flatness as well as mitigating the effects of the scrolls being of different heights.
  • the above-described use of the more wear resistant portion to take the bulk of the load on the channel seal tends to reduce friction during operation of the scroll pump, thus saving power and generating less waste heat.
  • Figure 3 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal 300 for the scroll pump 100 of Figure 1 according to another embodiment.
  • the channel seal 300 of Figure 3 may be used as the first channel seal 170 or the second channel seal 180 in the scroll pump 100 of Figure 1.
  • the channel seal 300 comprises an inner portion 310 and an outer portion 320 located around the periphery of the inner portion 310.
  • the channel seal 300 defines a radial direction and an axial direction
  • the outer portion 320 is located radially outwards of the inner portion 310.
  • the outer portion 320 is bonded to the inner portion 310.
  • the channel seal 300 has an overall circular shape.
  • the inner portion 310 has a circular shape with a spiral aperture matching the shape of the spiral wall of the scroll onto which the channel seal 300 fits, and a circular aperture matching the shape of the part of the drive shaft of the scroll pump around which the channel seal 300 is placed.
  • the outer portion 320 has a ring shape.
  • the channel seal 300 and its inner and outer portions 310, 320 may have other different shapes, as long as the functions described herein are fulfilled.
  • the outer portion 320 is formed from a material which is more wear resistant than the inner portion 310.
  • the outer portion 320 may be formed from a harder material than the inner portion 310.
  • the outer portion 320 may be formed from a different type of material to the material from which the inner portion 310 is formed.
  • the inner portion 310 may be formed from Polytetrafluoroethylene (PTFE) with a certain filler and the outer portion 320 may be formed from PTFE with a different filler which makes the outer portion 220 more wear resistant.
  • PTFE Polytetrafluoroethylene
  • the inner portion 310 may be formed from PTFE with a certain filler and the outer portion 320 may be formed from PTFE with the same filler but at a different density which makes the outer portion 320 more wear resistant.
  • a more wear resistant material for the channel seal is a material which wears down at a lower rate when used in a given scroll pump (e.g. the scroll pump 100 of Figure 1) in a given set of operating conditions, compared to a less wear resistant material for the channel seal in that same given scroll pump in the same given set of operating conditions.
  • the channel seal 300 further comprises a sacrificial bedding-in layer 330 disposed on the outer portion 320.
  • the sacrificial beddingin layer 330 is located radially outwards of the inner portion 310 and is layered onto the outer portion 320 in the axial direction.
  • the channel seal 300 also further comprises a base portion 340.
  • the base portion 340 and the outer portion 320 together define a cavity within which the inner portion 310 is located.
  • the inner portion 310 is layered onto the base portion 340 in the axial direction.
  • the base portion 340 is integrally formed with the outer portion 320 and is formed from the same material as the outer portion 320.
  • the thickness of the sacrificial bedding-in layer 330 added to the thickness of the outer portion 320 is substantially the same as the thickness of the inner portion 310 added to the thickness of the base portion 340.
  • the sacrificial bedding-in layer 330 covers a side of the outer portion 320 such that the exposed surface of the sacrificial bedding-in layer 330 is substantially flush with a surface of a side of the inner portion 310.
  • the sacrificial bedding-in layer 330 is integrally formed with the inner portion 310. In other words, the inner portion 310 and the sacrificial bedding-in layer 330 together form a single piece of material.
  • the sacrificial bedding-in layer 330 is formed from the same material as the inner portion 310.
  • the inner portion 310 may be veneer bonded to the outer portion 320 and the base portion 340 or the inner portion 310 may be formed as a coating on the outer portion 320 and the base portion 340.
  • the above-described structure means that, in the same way as the embodiment of Figure 2, the surface of the inner portion 310 which is subject to wear during operation of the scroll pump is axially offset from the surface of the outer portion 320 which is subject to wear during operation of the scroll pump (after the sacrificial bedding-in layer 330 has been worn through).
  • the axial offset is equal to the thickness of the sacrificial bedding-in layer 330.
  • the channel seal 300 when the channel seal 300 is initially installed in a scroll pump and the scroll pump is operated, the channel seal 300 goes through a bedding-in phase in which the inner portion 310 and the sacrificial bedding-in layer 330 are worn down (at the same rate) until the part of the scroll pump wearing down the sacrificial beddingin layer 330 wears completely through the sacrificial bedding-in layer 330 and reaches the outer portion 320.
  • the more wear resistant outer portion 320 takes more load than the inner portion 310, and the wear rate is mostly determined by the outer portion 220.
  • the above described structure advantageously means that the channel seal 300 can be relatively quickly initially bedded-in on less wear resistant material (i.e. the material of the inner portion 310 and the sacrificial bedding-in layer 330), and then the more wear resistant material (i.e. the material of the outer portion 320) is subjected to the bulk of the load on the channel seal 300, thus providing longer overall service life for the channel seal 300.
  • the abovedescribed quick bedding-in tends to be desirable for scroll pumps because it tends to allow the scroll pump to reach full operational capacity quickly and with less run-time.
  • the above-described structure also tends to allow a manufacturer of the scroll pump to avoid the use of extra specialised bedding-in equipment. This in turn tends to reduce costs for the supplier.
  • the above-described bedding-in process also tends to help mitigate the effects of the seal being manufactured with imperfect flatness as well as mitigating the effects of the scrolls being of different heights.
  • the above-described use of the more wear resistant portion to take the bulk of the load on the channel seal tends to reduce friction during operation of the scroll pump, thus saving power and generating less waste heat. It will be appreciated that various modifications/deviations may be made to the above described embodiments without departing from the scope of the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)

Abstract

A channel seal (200, 300) for a scroll pump (100). The channel seal comprises an inner portion (210, 310) and an outer portion (220, 320) located around the periphery of the inner portion. The outer portion is formed from a more wear resistant material than the inner portion. A surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump.

Description

SEAL FOR SCROLL PUMP
FIELD OF THE INVENTION
The present invention relates to scroll pumps.
BACKGROUND
Scroll pumps are a known type of pump used in various different industries to pump fluid. Scroll pumps operate by using the relative motion of two intermeshed scrolls (known as a fixed scroll and an orbiting scroll) to pump fluid. Each of the fixed and orbiting scrolls includes a spiral wall extending from a base.
Scroll pumps include seals to prevent leakage of fluid from various parts of the scroll pump.
SUMMARY OF INVENTION
In an aspect, there is provided a channel seal for a scroll pump. The channel seal comprises an inner portion and an outer portion located around the periphery of the inner portion. The outer portion is formed from a more wear resistant material than the inner portion. A surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump.
The channel seal may further comprise a sacrificial bedding-in layer disposed on the outer portion.
The sacrificial bedding-in layer may be integrally formed with the inner portion.
The axial offset may be equal to a thickness of the sacrificial bedding-in layer. The inner portion may be formed from a different type of material to the outer portion.
The outer portion may be formed from a harder material than the inner portion.
The sacrificial bedding-in layer may be formed from the same material as the inner portion.
The channel seal may further comprise a base portion.
The base portion and the outer portion may together define a cavity within which the inner portion is located.
The base portion may be integrally formed with the outer portion.
The base portion may be formed from the same type of material as the outer portion.
The inner portion may be veneer bonded to the base portion and the outer portion.
The inner portion may be formed as a coating on the base portion and the outer portion.
The inner portion may comprise a spiral aperture.
In another aspect, there is provided a scroll pump comprising the channel seal of the above aspect.
In yet another aspect, there is provided a method of manufacturing a channel seal for a scroll pump. The method comprises forming an inner portion, and forming an outer portion around the periphery of the inner portion such that a surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump, wherein the outer portion is formed from a more wear resistant material than the inner portion.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a schematic illustration (not to scale) showing a cross-sectional view of a scroll pump;
Figure 2 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal for the scroll pump; and
Figure 3 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of another channel seal for the scroll pump.
DETAILED DESCRIPTION
Figure 1 is a schematic illustration (not to scale) showing a cross-sectional view of a scroll pump 100.
The scroll pump 100 comprises housing portions 110, a fixed scroll 120, an orbiting scroll 130, a drive shaft 140, an actuator 150, a bearing assembly 160, a first channel seal 170, and a second channel seal 180.
In this embodiment, the housing portions 110 and the fixed scroll 120 together define an overall housing of the scroll pump 100 within which other components of the scroll pump 100 are located. However, it will be appreciated that, in other embodiments, the fixed scroll 120 may not define any of the overall housing of the scroll pump 100 and instead may be located entirely within an overall housing. In this embodiment, the orbiting scroll 130 is located within the overall housing of the scroll pump 100.
The orbiting scroll 130 is intermeshed with the fixed scroll 120 to define a space (or channel) which is used by the scroll pump 100 during operation to pump fluid (e.g. a gas). The orbiting scroll 130 is configured to orbit relative to the fixed scroll 120 to pump fluid from an inlet (not shown) of the scroll pump 100 to an outlet (not shown) of the scroll pump 100. The precise physical mechanism by which fluid is pumped by the orbiting of the orbiting scroll 130 relative to the fixed scroll 120 is well understood and will not be described herein for the sake of brevity.
The fixed scroll 120 comprises a first base 122 and a first spiral wall 124. The orbiting scroll 130 comprises a second base 132 and a second spiral wall 134. The first spiral wall 124 and second spiral wall 134 are intermeshed with each other. Furthermore, the first spiral wall 124 extends perpendicularly from the first base 122 towards the second base 132 such that an end surface (also known as the tip) of the first spiral wall 124 is proximate to but not in contact with an opposing surface of the second base 132. The second spiral wall 134 extends perpendicularly from the second base 132 towards the first base 122 such that an end surface (or tip) of the second spiral wall 134 is proximate to but not in contact with an opposing surface of the first base 122. The first channel seal 170 is sandwiched between the end surface of the second spiral wall 134 and the opposing surface of the first base 122. The second channel seal 180 is sandwiched between the end surface of the first spiral wall 124 and the opposing surface of the second base 132. The fixed scroll 120 and orbiting scroll 130 may be biased together by a biasing apparatus (not shown) of the scroll pump (e.g. one or more springs).
In this embodiment, the first base 122 and first spiral wall 124 are integrally formed with each other, and the second base 132 and second spiral wall 134 are integrally formed with each other. However, in other embodiments, one or both of the spiral walls 124, 134 are not integrally formed with their respective bases 122, 132.
The drive shaft 140 is coupled to the orbiting scroll 130 and configured to rotate to drive the orbiting of the orbiting scroll 130. The drive shaft 140 is located within the overall housing of the scroll pump 100 and mounted via the bearing assembly 160 which facilitates rotation of the drive shaft 140. In this embodiment, the drive shaft 140 extends through both the fixed scroll 120 and the orbiting scroll 130 is mounted at an end of the draft shaft 140.
The actuator 150 (e.g. an electric motor) is coupled to the drive shaft 140 and configured to actuate the drive shaft 140 to cause the drive shaft 140 to rotate to drive the orbiting of the orbiting scroll 130. The actuator 150 is located within the overall housing of the scroll pump 100 and mounted around the drive shaft 140.
The bearing assembly 160 mechanically couples the drive shaft 140 to the orbiting scroll 130 and the overall housing of the scroll pump 100 such that the drive shaft 140 is able to rotate within the scroll pump 100 to drive the orbiting scroll 130.
The first channel seal 170 and the second channel seal 180 provide axial seals to prevent/oppose leakage of fluid axially between different sections of the space (or channel) which is used by the scroll pump 100 during operation to pump fluid. During operation of the scroll pump 100, due to the orbiting of the orbiting scroll 130, the end surface of the first spiral wall 124 rubs against the second channel seal 180 and the end surface of the second spiral wall 134 rubs against the first channel seal 170. Thus, the first and second channel seals 170, 180 are subject to wear from the rubbing over their lifetime. Seal structures which may be used for the first and second channel seals 170, 180 will now be described with reference to Figure 2 and Figure 3.
Figure 2 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal 200 for the scroll pump 100 of Figure 1 according to an embodiment. The channel seal 200 of Figure 2 may be used as the first channel seal 170 or the second channel seal 180 in the scroll pump 100 of Figure 1.
The channel seal 200 comprises an inner portion 210 and an outer portion 220 located around the periphery of the inner portion 210. The channel seal 200 defines a radial direction and an axial direction, and the outer portion 220 is located radially outwards of the inner portion 210. The outer portion 220 may be bonded to the inner portion 210. Alternatively, the outer portion 220 may be a separate piece to the inner portion 210 and not bonded or attached.
In this embodiment, the channel seal 200 has an overall circular shape. In this embodiment, the inner portion 210 has a circular shape with a spiral aperture matching the shape of the spiral wall of the scroll onto which the channel seal 200 fits, and a circular aperture matching the shape of the part of the drive shaft of the scroll pump around which the channel seal 200 is placed. In this embodiment, the outer portion 220 has a ring shape. However, it will be appreciated that the channel seal 200 and its inner and outer portions 210, 220 may have other different shapes, as long as the functions described herein are fulfilled.
The outer portion 220 is formed from a material which is more wear resistant than the inner portion 210. For example, the outer portion 220 may be formed from a harder material than the inner portion 210. The outer portion 220 may be formed from a different type of material to the material from which the inner portion 210 is formed. For example, the inner portion 210 may be formed from Polytetrafluoroethylene (PTFE) with a certain filler and the outer portion 220 may be formed from PTFE with a different filler which makes the outer portion 220 more wear resistant. As another example, the inner portion 210 may be formed from PTFE with a certain filler and the outer portion 220 may be formed from PTFE with the same filler but at a different density which makes the outer portion 220 more wear resistant. In the context of this specification, a more wear resistant material for the channel seal is a material which wears down at a lower rate when used in a given scroll pump (e.g. the scroll pump 100 of Figure 1) in a given set of operating conditions, compared to a less wear resistant material for the channel seal in that same given scroll pump in the same given set of operating conditions.
In this embodiment, the inner portion 210 is thicker than the outer portion 220. In this embodiment, the channel seal 200 further comprises a sacrificial bedding-in layer 230 disposed on the outer portion 220. The sacrificial bedding- in layer 230 is located radially outwards of the inner portion 210 and is layered onto the outer portion 220 in the axial direction. The sacrificial bedding-in layer 230 has a thickness such that the thickness of the sacrificial bedding-in layer 230 added to the thickness of the outer portion 220 is substantially the same as the thickness of the inner portion 210. In other words, the sacrificial bedding-in layer 230 covers a side of the outer portion 220 such that the exposed surface of the sacrificial bedding-in layer 230 is substantially flush with a surface of a side of the inner portion 210. The sacrificial bedding-in layer 230 is integrally formed with the inner portion 210. In other words, the inner portion 210 and the sacrificial bedding-in layer 230 together form a single piece of material. The sacrificial bedding-in layer 230 is formed from the same material as the inner portion 210.
The above-described structure means that the surface of the inner portion 210 which is subject to wear during operation of the scroll pump is axially offset from the surface of the outer portion 220 which is subject to wear during operation of the scroll pump (after the sacrificial bedding-in layer 230 has been worn through). The axial offset is equal to the thickness of the sacrificial bedding-in layer 230.
When the channel seal 200 is initially installed in a scroll pump and the scroll pump is operated, the channel seal 200 goes through a bedding-in phase in which the inner portion 210 and the sacrificial bedding-in layer 230 are worn down (at the same rate) until the part of the scroll pump wearing down the sacrificial bedding-in layer 230 wears completely through the sacrificial beddingin layer 230 and reaches the outer portion 220. Following this bedding-in phase, during subsequent operation of the scroll pump, the more wear resistant outer portion 220 takes more load than the inner portion 210, and the wear rate is mostly determined by the outer portion 220.
Thus, the above described structure advantageously means that the channel seal 200 can be relatively quickly initially bedded-in on less wear resistant material (i.e. the material of the inner portion 210 and the sacrificial bedding-in layer 230), and then the more wear resistant material (i.e. the material of the outer portion 220) is subjected to the bulk of the load on the channel seal 200, thus providing longer overall service life for the channel seal 200. The abovedescribed quick bedding-in tends to be desirable for scroll pumps because it tends to allow the scroll pump to reach full operational capacity quickly and with less run-time. The above-described structure also tends to allow a manufacturer of the scroll pump to avoid the use of extra specialised bedding-in equipment. This in turn tends to reduce costs for the supplier. The above-described bedding-in process also tends to help mitigate the effects of the seal being manufactured with imperfect flatness as well as mitigating the effects of the scrolls being of different heights. The above-described use of the more wear resistant portion to take the bulk of the load on the channel seal tends to reduce friction during operation of the scroll pump, thus saving power and generating less waste heat.
Figure 3 is a schematic illustration (not to scale) showing a plan view, a cross- sectional view and a zoomed-in cross-sectional view of a channel seal 300 for the scroll pump 100 of Figure 1 according to another embodiment. The channel seal 300 of Figure 3 may be used as the first channel seal 170 or the second channel seal 180 in the scroll pump 100 of Figure 1.
The channel seal 300 comprises an inner portion 310 and an outer portion 320 located around the periphery of the inner portion 310. In other words, the channel seal 300 defines a radial direction and an axial direction, and the outer portion 320 is located radially outwards of the inner portion 310. The outer portion 320 is bonded to the inner portion 310. In this embodiment, the channel seal 300 has an overall circular shape. In this embodiment, the inner portion 310 has a circular shape with a spiral aperture matching the shape of the spiral wall of the scroll onto which the channel seal 300 fits, and a circular aperture matching the shape of the part of the drive shaft of the scroll pump around which the channel seal 300 is placed. In this embodiment, the outer portion 320 has a ring shape. However, it will be appreciated that the channel seal 300 and its inner and outer portions 310, 320 may have other different shapes, as long as the functions described herein are fulfilled. The outer portion 320 is formed from a material which is more wear resistant than the inner portion 310. For example, the outer portion 320 may be formed from a harder material than the inner portion 310. The outer portion 320 may be formed from a different type of material to the material from which the inner portion 310 is formed. For example, the inner portion 310 may be formed from Polytetrafluoroethylene (PTFE) with a certain filler and the outer portion 320 may be formed from PTFE with a different filler which makes the outer portion 220 more wear resistant. As another example, the inner portion 310 may be formed from PTFE with a certain filler and the outer portion 320 may be formed from PTFE with the same filler but at a different density which makes the outer portion 320 more wear resistant. In the context of this specification, a more wear resistant material for the channel seal is a material which wears down at a lower rate when used in a given scroll pump (e.g. the scroll pump 100 of Figure 1) in a given set of operating conditions, compared to a less wear resistant material for the channel seal in that same given scroll pump in the same given set of operating conditions.
In this embodiment, the channel seal 300 further comprises a sacrificial bedding-in layer 330 disposed on the outer portion 320. The sacrificial beddingin layer 330 is located radially outwards of the inner portion 310 and is layered onto the outer portion 320 in the axial direction. In this embodiment, the channel seal 300 also further comprises a base portion 340. The base portion 340 and the outer portion 320 together define a cavity within which the inner portion 310 is located. The inner portion 310 is layered onto the base portion 340 in the axial direction. In this embodiment, the base portion 340 is integrally formed with the outer portion 320 and is formed from the same material as the outer portion 320. In this embodiment, the thickness of the sacrificial bedding-in layer 330 added to the thickness of the outer portion 320 is substantially the same as the thickness of the inner portion 310 added to the thickness of the base portion 340. The sacrificial bedding-in layer 330 covers a side of the outer portion 320 such that the exposed surface of the sacrificial bedding-in layer 330 is substantially flush with a surface of a side of the inner portion 310. The sacrificial bedding-in layer 330 is integrally formed with the inner portion 310. In other words, the inner portion 310 and the sacrificial bedding-in layer 330 together form a single piece of material. The sacrificial bedding-in layer 330 is formed from the same material as the inner portion 310.
In this embodiment, the inner portion 310 may be veneer bonded to the outer portion 320 and the base portion 340 or the inner portion 310 may be formed as a coating on the outer portion 320 and the base portion 340.
The above-described structure means that, in the same way as the embodiment of Figure 2, the surface of the inner portion 310 which is subject to wear during operation of the scroll pump is axially offset from the surface of the outer portion 320 which is subject to wear during operation of the scroll pump (after the sacrificial bedding-in layer 330 has been worn through). The axial offset is equal to the thickness of the sacrificial bedding-in layer 330.
In the same way as described above for the embodiment of Figure 2, when the channel seal 300 is initially installed in a scroll pump and the scroll pump is operated, the channel seal 300 goes through a bedding-in phase in which the inner portion 310 and the sacrificial bedding-in layer 330 are worn down (at the same rate) until the part of the scroll pump wearing down the sacrificial beddingin layer 330 wears completely through the sacrificial bedding-in layer 330 and reaches the outer portion 320. Following this bedding-in phase, during subsequent operation of the scroll pump, the more wear resistant outer portion 320 takes more load than the inner portion 310, and the wear rate is mostly determined by the outer portion 220.
Thus, the above described structure advantageously means that the channel seal 300 can be relatively quickly initially bedded-in on less wear resistant material (i.e. the material of the inner portion 310 and the sacrificial bedding-in layer 330), and then the more wear resistant material (i.e. the material of the outer portion 320) is subjected to the bulk of the load on the channel seal 300, thus providing longer overall service life for the channel seal 300. The abovedescribed quick bedding-in tends to be desirable for scroll pumps because it tends to allow the scroll pump to reach full operational capacity quickly and with less run-time. The above-described structure also tends to allow a manufacturer of the scroll pump to avoid the use of extra specialised bedding-in equipment. This in turn tends to reduce costs for the supplier. The above-described bedding-in process also tends to help mitigate the effects of the seal being manufactured with imperfect flatness as well as mitigating the effects of the scrolls being of different heights. The above-described use of the more wear resistant portion to take the bulk of the load on the channel seal tends to reduce friction during operation of the scroll pump, thus saving power and generating less waste heat. It will be appreciated that various modifications/deviations may be made to the above described embodiments without departing from the scope of the invention.
REFERENCE NUMERAL LIST
100: scroll pump
110: housing portion
120: fixed scroll
122: first base
124: first spiral wall
130: orbiting scroll
132: second base
134: second spiral wall
140: drive shaft
150: actuator
160: bearing assembly
170: first channel seal
180: second channel seal
200, 300: channel seal
210, 310: inner portion
220, 320: outer portion
230, 330: sacrificial bedding-in layer
340: base portion

Claims

1. A channel seal for a scroll pump, the channel seal comprising: an inner portion; and an outer portion located around the periphery of the inner portion, wherein the outer portion is formed from a more wear resistant material than the inner portion, and wherein a surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump.
2. The channel seal of claim 1 , further comprising a sacrificial bedding-in layer disposed on the outer portion.
3. The channel seal of claim 2, wherein the sacrificial bedding-in layer is integrally formed with the inner portion.
4. The channel seal of claim 2 or 3, wherein the axial offset is equal to a thickness of the sacrificial bedding-in layer.
5. The channel seal of any preceding claim, wherein the inner portion is formed from a different type of material to the outer portion.
6. The channel seal of any preceding claim, wherein the outer portion is formed from a harder material than the inner portion.
7. The channel seal of any preceding claim when dependent on claim 2, wherein the sacrificial bedding-in layer is formed from the same material as the inner portion.
8. The channel seal of any preceding claim, further comprising a base portion, wherein the base portion and the outer portion together define a cavity within which the inner portion is located.
9. The channel seal of claim 8, wherein the base portion is integrally formed with the outer portion.
10. The channel seal of claim 8 or 9, wherein the base portion is formed from the same type of material as the outer portion.
11 . The channel seal of any of claims 8 to 10, wherein the inner portion is veneer bonded to the base portion and the outer portion.
12. The channel seal of any of claims 8 to 10, wherein the inner portion is formed as a coating on the base portion and the outer portion.
13. The channel seal of any preceding claim, wherein the inner portion comprises a spiral aperture.
14. A scroll pump comprising the channel seal of any preceding claim.
15. A method of manufacturing a channel seal for a scroll pump, the method comprising: forming an inner portion; and forming an outer portion around the periphery of the inner portion such that a surface of the inner portion which is subject to wear during operation of the scroll pump is axially offset from a surface of the outer portion which is subject to wear during operation of the scroll pump, wherein the outer portion is formed from a more wear resistant material than the inner portion.
EP23828240.4A 2022-12-20 2023-12-14 Seal for scroll pump Pending EP4638966A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2219247.0A GB2625552B (en) 2022-12-20 2022-12-20 Seal for scroll pump
PCT/GB2023/053236 WO2024134146A1 (en) 2022-12-20 2023-12-14 Seal for scroll pump

Publications (1)

Publication Number Publication Date
EP4638966A1 true EP4638966A1 (en) 2025-10-29

Family

ID=85035697

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23828240.4A Pending EP4638966A1 (en) 2022-12-20 2023-12-14 Seal for scroll pump

Country Status (4)

Country Link
EP (1) EP4638966A1 (en)
CN (1) CN120435623A (en)
GB (1) GB2625552B (en)
WO (1) WO2024134146A1 (en)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2709450B2 (en) * 1995-07-04 1998-02-04 西芝電機株式会社 Scroll compressor
JPH09158860A (en) * 1995-12-13 1997-06-17 Mitsubishi Heavy Ind Ltd Scroll compressor
JP2000009062A (en) * 1998-06-18 2000-01-11 Sanden Corp Scroll type compressor
WO2000006906A1 (en) * 1998-07-30 2000-02-10 Varian, Inc. Scroll-type vacuum pump
GB0912162D0 (en) * 2009-07-14 2009-08-26 Edwards Ltd Scroll compressor
GB2548607B (en) * 2016-03-23 2020-05-06 Edwards Ltd Scroll pump tip sealing
GB2585903B (en) * 2019-07-22 2021-12-08 Edwards Ltd Scroll Pump

Also Published As

Publication number Publication date
CN120435623A (en) 2025-08-05
GB2625552A (en) 2024-06-26
GB2625552B (en) 2025-10-10
GB202219247D0 (en) 2023-02-01
WO2024134146A1 (en) 2024-06-27

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