EP-4739887-A1 - PUMP ASSEMBLY AND VACUUM PUMP WITH REDUCED SEAL REQUIREMENTS

Abstract

A pump assembly (100) for a vacuum pump, comprising: an inlet side (110) and an outlet side (120) and a plurality of pump chambers (130) arranged therebetween; a first assembly component (140) defining a first sealing face (141) and a second assembly component (150) defining a second sealing face (151); wherein the first assembly component (140) and the second assembly component (150) are arranged to be joined together at the first and second sealing faces (141, 151) thereby providing a seal (160) for substantially sealing the plurality of pump chambers (130) from an exterior of the pump assembly (170); wherein the seal (160) comprises a labyrinth seal.

Inventors

• LONG, Cainan
• NORTH, MICHAEL HENRY
• KAILASAM, Sivabalan
• TOMKINS, MARK EDWARD

Assignees

• Edwards Limited

Dates

Publication Date

20260513

Application Date

20240603

Claims (15)

1. 1. A pump assembly for a vacuum pump, comprising: an inlet side and an outlet side and a plurality of pump chambers arranged therebetween; a first assembly component defining a first sealing face and a second assembly component defining a second sealing face, wherein the first assembly component and the second assembly component are arranged to be joined together at the first and second sealing faces thereby providing a seal for substantially sealing the plurality of pump chambers from an exterior of the pump assembly; wherein the seal comprises a labyrinth seal.
2. 2. A pump assembly according to claim 1 , wherein: the labyrinth seal comprises at least one continuous ridge provided in the first sealing face and/or the second sealing face, the at least one continuous ridge extending around the plurality of pump chambers.
3. 3. A pump assembly according to claim 2, wherein: the at least one continuous ridge comprises at least one hollow ridge.
4. 4. A pump assembly according to any one of claims 2-3, wherein: the at least one continuous ridge is detachable from both the first and second sealing faces.
5. 5. A pump assembly according to any one of claims 2-4, wherein: the at least one continuous ridge comprises a plurality of continuous ridges.
6. 6. A pump assembly according to any one of claims 2-5, wherein: the labyrinth seal further comprises at least one continuous groove provided in the second sealing face and/or the first sealing face, the at least one continuous groove extending around the plurality of pump chambers, for mating with the at least one continuous ridge.
7. 7. A pump assembly according to claim 6, wherein: the at least one continuous groove provides an interference fit to the at least one continuous ridge.
8. 8. A pump assembly according to any one of claims 6-7, further comprising: a spacer arranged between the first and second sealing faces, the spacer defining a gap between the first and second components.
9. 9. A pump assembly according to claim 8, wherein: the spacer comprises a protrusion extending from the first or second sealing face.
10. 10. A pump assembly according to claim 9, wherein: the first or second assembly component comprising the spacer, further comprises a carving arranged adjacent the protrusion to provide a thermal break.
11. 11. A pump assembly according to any one of claims 8-10, wherein the plurality of pump chambers comprises an inlet pump chamber at the inlet side of the pump assembly, configured to receive process gas from a vacuum system, and at least one downstream pump chamber arranged between the inlet pump chamber and the outlet side of the pump assembly; wherein the labyrinth seal further comprises at least one gas pocket; and wherein the first assembly component and/or the second assembly component comprise at least one gas channel arranged to fluidly connect the at least one gas pocket to at least one of the downstream pump chambers, such that the at least one gas pocket can be pressure equalized with a pump pressure of the downstream pump chambers.
12. 12. A pump assembly according to any one of claims 8-11 , further comprising: a sacrificial sealing component arranged between the first and second sealing faces.
13. 13. A pump assembly according to any preceding claim, wherein: the first assembly component and the second assembly component are selected from the list of components consisting of: a stator component; a thermal break plate; and a head plate.
14. 14. A vacuum pump comprising the pump assembly according to any preceding claim.
15. 15. A method of sealing a first assembly component to a second assembly component in a pump assembly for a vacuum pump, the method comprising: providing, first and second assembly components of a pump assembly, wherein the pump assembly has an inlet side and an outlet side and a plurality of pump chambers arranged therebetween; joining, a first sealing face of the first assembly component to a second sealing face of the second assembly component, thereby providing a seal for substantially sealing the plurality of pump chambers from an exterior of the pump assembly; wherein the method further comprises the step of: configuring the joining of the first and second sealing faces such that the seal comprises a labyrinth seal.

Description

PUMP ASSEMBLY AND VACUUM PUMP WITH REDUCED SEAL REQUIREMENTS FIELD OF THE INVENTION The field of the invention relates to vacuum pumps, and more specifically to vacuum pumps that can allow for elastomer seals between assembly components to be reduced or removed. BACKGROUND Vacuum pumps are typically employed as a component of a vacuum system to evacuate working gases from the system. These pumps can be used to evacuate fabrication equipment used in, for example, the production of semiconductors. Rather than performing compression from a vacuum to atmosphere in a single stage using a single pump, it is common in such applications to provide multi-stage vacuum pumps wherein each stage performs a portion of the compression range required to transition from a vacuum to atmospheric pressure. A clamshell pump is an example of a multi-stage vacuum pump. This type of pump typically requires the use of two stator shell halves and two end plates on the two sides of the stator halves to enclose the pumping area. Traditionally, longitudinal and annular seals are used between the two stator halves and between the stator halves and the two end plates, respectively, to prevent leakages between the pump and the surrounding environment. A screw pump is a further example of a multi-stage vacuum pump. This type of pump comprises a pump assembly having two cooperative screw rotors contained within a stator having an inlet side and outlet side. The stator interfaces with end plates to effectively seal the plurality of pump chambers defined by the stator and screw rotors, from an exterior of the pump assembly. The stator and end plates are typically clamped together (for instance using bolts) with annular seals therebetween. Traditionally, elastomer seals (such as o-rings) are used to seal assembly components of a pump assembly together in a fluid-tight manner. However, it can still be difficult to achieve an effective seal. Moreover, there are applications where the use of elastomer seals is not desirable. For example, they may be susceptible to degradation and loss of sealing at certain operational temperatures and under certain corrosive process gas environments. Further, they may be susceptible to outgassing and have unacceptable gas permeability under certain conditions. It is also the case that, even at low temperature operation, the removal of elastomer seals can yield desirable benefits such as reducing the cost of a vacuum pump apparatus, mitigating the need for frequent service intervals, and increasing the overall lifespan of a vacuum pump. Compounding these issues is that some vacuum pumps require a thermal break feature between the pump mechanism and peripheral components (such as pump bearings and oil). This is because a pump mechanism may be required to operate at relatively high temperatures (for instance greater than 150 degrees Celsius) in comparison to the bearings, oil and other components, which must be kept at lower temperatures (for instance, less than 80 degrees Celsius). Hence any sealing mechanism between pump assembly components may also need to consider how such a thermal break between the assembly components can be maintained. Traditionally this has been achieved through the provision of low-conductivity thermal break plates arranged between assembly components, sealed to said assembly components with additional elastomer seals therebetween. Therefore, a pump assembly for a vacuum pump wherein assembly components can be sealed together in such applications whilst avoiding or reducing the need for elastomer seals, is desirable. SUMMARY OF THE INVENTION In an aspect, there is provided a pump assembly for a vacuum pump, comprising: an inlet side and an outlet side and a plurality of pump chambers arranged therebetween; a first assembly component defining a first sealing face; and a second assembly component defining a second sealing face; wherein the first assembly component and the second assembly component are arranged to be joined together at the first and second sealing faces, thereby providing a seal for substantially sealing the plurality of pump chambers from an exterior of the pump assembly; wherein the seal comprises a labyrinth seal. The removal of an elastomer seal between two assembly components of a pump assembly will result in a pump assembly that naturally leaks. This leakage is typically directed into the pump from the exterior of the pump assembly, because the pump is operating at sub-atmospheric pressures. It has been found that by providing an interface between assembly components that is tortuous i.e. comprises twists or turns and is generally complex, vice linear or planar, results in an increased path length for gases leaking into the pump assembly and reduces the leakage experienced. Such a labyrinth seal may also comprise limited contact-sealing between the first and second sealing faces, and can encourage controlled fluid vortices between the sealing faces, further providi