Pump assemblies and vacuum pumps with reduced sealing 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) disposed between them; a first assembly component (140) defining a first sealing surface (141); and a second assembly component (150) defining a second sealing surface (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 surfaces (141, 151), thereby providing a seal (160) for substantially sealing the plurality of pump chambers (130) from the outside of the pump assembly (170), the seal (160) including a labyrinth seal.

Description

Technical Field

[0001] The field of the present invention relates to vacuum pumps, and more particularly to vacuum pumps that can reduce or eliminate elastomeric seals between assembled components.

Background Art

[0002] Vacuum pumps are generally used as components of a vacuum system for exhausting working gas from a system. These pumps can be used, for example, to evacuate manufacturing equipment used in semiconductor manufacturing. In such applications, instead of using a single pump to perform compression from vacuum to atmospheric pressure in a single stage, it is common to provide a multi-stage vacuum pump in which each stage performs a part of the compression range required for the transition from vacuum to atmospheric pressure.

[0003] A claw shell pump is an example of a multi-stage vacuum pump. This type of pump generally requires two stator shell halves and two end plates on both sides of the stator half to surround the pump region. Conventionally, longitudinal seals and annular seals have been used between the two stator halves and between the stator half and the two end plates, respectively, to prevent leakage between the pump assembly and the surrounding environment.

[0004] The pump assembly of a screw pump is a further example of a multi-stage pump. This type of pump includes a pump assembly having two cooperating screw rotors housed within a stator having an inlet side and an outlet side. The stator abuts an end plate to effectively seal a plurality of pump chambers defined by the stator and the screw rotors from outside the pump assembly. The stator and the end plate are generally clamped together (e.g., using bolts) along with an annular seal therebetween.

[0005] Traditionally, elastomer seals (such as O-rings) have been used to seal the components of pump assemblies in a fluid-seal manner. However, even with these, achieving an effective seal can be difficult. Furthermore, there are applications where the use of elastomer seals is undesirable. For example, elastomer seals are prone to degradation and loss of sealing ability under certain operating temperatures and corrosive process gas environments. In addition, elastomer seals may exhibit gas outgassing under certain conditions and may have unacceptable gas permeability. It is also true that removing elastomer seals, even at low temperatures, can offer desirable benefits such as reduced vacuum pump costs, less need for frequent maintenance intervals, and a longer overall lifespan for the vacuum pump.

[0006] Further complicating these issues is the fact that some vacuum pumps require a thermal break (thermal insulation) function between the pump mechanism and surrounding components (such as pump bearings and oil). This is because the pump mechanism may be required to operate at relatively high temperatures (e.g., above 150°C) compared to bearings, oil, and other components that need to be kept at lower temperatures (e.g., below 80°C). Therefore, the sealing mechanism between pump assembly components must take into account how to maintain thermal break between the assembly components. Traditionally, this has been achieved by placing low-conductivity thermal break plates (thermal insulation plates) between the assembly components and sealing the assembly components with an additional elastomer seal between them. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, in such applications, there is a need for a pump assembly for a vacuum pump that can seal the assembly components together while avoiding or reducing the need for elastomer seals. [Means for solving the problem]

[0008] In one embodiment, a pump assembly for a vacuum pump is provided, comprising: an inlet side and an outlet side and a plurality of pump chambers disposed between them; a first assembly component defining a first sealing surface; and a second assembly component defining a second sealing surface, wherein the first and second assembly components are arranged to be joined together at the first and second sealing surfaces, respectively, thereby providing a seal for substantially sealing the plurality of pump chambers from the outside of the pump assembly, the seal including a labyrinth seal.

[0009] Removing the elastomer seal between two assembly components of a pump assembly would naturally lead to leakage from the pump assembly. This leakage typically flows from outside the pump assembly into the pump, as the pump operates at a pressure lower than atmospheric pressure. Providing an interface between assembly components that is intricate, i.e., includes twists or bends, and is generally complex, rather than being linear or planar, has been shown to increase the path length of gas leaking into the pump assembly, thereby reducing leakage. Such labyrinth seals can also include a limited contact seal between the first and second sealing surfaces, which can promote controlled fluid vortices between the sealing surfaces and further provide a sealing effect. Thus, the pump assembly can be deployed without the elastomer seal, making it suitable for use in high-temperature or highly corrosive operating environments where the elastomer seal would otherwise degrade or be unsuitable. This also reduces the costs associated with manufacturing and maintaining vacuum pumps with pump assemblies and further reduces the frequency of maintenance required once the pump is deployed. These unique advantages are particularly relevant to screw pumps, multistage Roots pumps, or Roots claw pumps, as well as to the removal of elastomer seals currently used between stator components, head plates, and thermal break plates (thermal insulation plates).

[0010] In some embodiments, the labyrinth seal includes at least one continuous ridge provided on a first sealing surface and / or a second sealing surface, the at least one continuous ridge extending around a plurality of pump chambers.

[0011] At least one continuous ridge may be located on the first or second sealing surface and may be defined by a ridge (e.g., having a toothed cross-section) extending around a plurality of pump chambers. At least one continuous ridge may also be defined by, for example, an engraving, which may necessarily define a relatively raised section adjacent to the engraving. At least one continuous ridge contributes to the intricate outline of the labyrinth seal in the direction from the outside of the pump assembly toward the inside of the pump assembly (i.e., toward the pump chambers). This helps to reduce leakage into the pump assembly and allows for the removal of the elastomer seal. In addition, at least one continuous ridge helps to reduce the surface area of ​​the first and second sealing surfaces that are directly adjacent to and / or in contact with each other. This helps reduce heat transfer across the interface, which is particularly relevant when the first and second assembly components are parts of the respective sections of a pump assembly that need to be maintained at different operating temperatures (for example, in a screw pump as described herein).

[0012] In some embodiments, at least one continuous ridge comprises at least one hollow ridge.

[0013] At least one continuous ridge can be formed to have a hollow tubular or valley-shaped cross-section. This reduces the heat capacity of at least one continuous ridge, further reducing heat transfer through the labyrinth seal and contributing to the thermal break type characteristics.

[0014] In some embodiments, at least one continuous ridge is separable from both the first and second sealing surfaces. In this regard, at least one continuous ridge can define a belt-like structure that can be attached between the first and second sealing surfaces (for example, by the position of the belt-like structure in notches present on the first and / or second sealing surfaces). Such embodiments can enable easier assembly, in particular, if the continuous ridge is manufactured to bendable to accommodate machining tolerances between the first and second sealing surfaces. Furthermore, the separable ridge can be replaced at a lower cost than replacing the entire interface (in the non-separable variant), if necessary.

[0015] In some embodiments, at least one continuous ridge comprises a plurality of continuous ridges.

[0016] By providing multiple raised sections, the labyrinth seal can be made more intricate, further reducing leakage into the pump assembly and making the elastomer seal easier to remove. Furthermore, the multiple raised sections provide a more robust and sturdy interface between the first and second sealing surfaces, while maintaining a reduced surface area of ​​contact between the two sealing surfaces (relative to a flat sealing surface). Therefore, heat transfer through the labyrinth seal can be reduced while still providing a robust interface.

[0017] In some embodiments, the labyrinth seal further comprises at least one continuous groove provided on a second sealing surface and / or a first sealing surface, the at least one continuous groove extending around a plurality of pump chambers to engage with at least one continuous protrusion.

[0018] It has been found that providing at least one continuous groove and at least one continuous ridge that engages with it makes the interface between the first and second sealing surfaces robust and strong. Furthermore, the labyrinth seal becomes more intricate, defining further twists and bends, which further promotes fluid vortices, all of which contribute to improved sealing. In the case of vacuum pumps, this further reduces the need for elastomer seals.

[0019] In some embodiments, at least one continuous groove provides interference fit to at least one continuous protrusion.

[0020] By providing an interference fit, a contact seal can be established between at least one continuous groove and at least one continuous ridge. This further improves the strength of the interface between the first sealing surface and the second sealing surface, while simultaneously minimizing gas leakage.

[0021] Some embodiments further include a spacer positioned between a first sealing surface and a second sealing surface, the spacer defining a gap between the first component and the second component.

[0022] It has been found that providing a spacer facilitates maintaining a gap between the first and second sealing surfaces that define the labyrinth seal. This gap contributes to the thermal break (thermal insulation) function of the labyrinth seal, reducing heat transfer through the seal. Therefore, the pump assembly can be used in applications where the first and second components form parts of each section of the pump assembly that need to be maintained at different temperatures. For example, the pump assembly can be used in a screw pump, where the pump mechanism (partly formed by either the first or second assembly component) needs to operate at a higher temperature than the surrounding components (partly formed by either the second or first assembly component). In fact, a more specific example is when the first component comprises a stator and the second component comprises a head plate. Furthermore, the presence of a gap between the first and second assembly components can reduce or eliminate the need for a separate thermal break plate in the pump assembly, thereby facilitating manufacturing and maintenance and reducing manufacturing costs.

[0023] A further advantage of the spacer is that the gap defined between the first and second sealing surfaces allows for the definition of additional pockets in the labyrinth seal. These pockets can promote fluid vortices and further contribute to the sealing effect.

[0024] In some embodiments, the spacer includes a ceramic material, which itself reduces heat conduction through the spacer and the labyrinth seal. This is because ceramic materials have low thermal conductivity. Any suitable ceramic material can be used, such as alumina, zirconia, or magnesia. Other materials with insulating properties can also be used.

[0025] The spacer may be a separate and independent component from the first and second assembly components, but in other embodiments, the spacer includes a projection extending from the first or second sealing surface.

[0026] A spacer protruding from the first or second seal surface can reduce the number of components for providing a labyrinth seal. Thereby, the manufacturing complexity and cost are reduced, and the maintenance complexity and cost of a vacuum pump including the pump assembly are reduced.

[0027] In some embodiments, the first or second assembly component including the spacer is disposed adjacent to the protrusion and further includes a notch (carving) that provides a thermal break.

[0028] In an embodiment where the spacer forms part of the first or second assembly component, the spacer will constitute a part of the first or second assembly component that directly contacts the other of the first or second assembly components. As a result, the spacer may provide a path for heat transfer through the labyrinth seal. To mitigate this effect, the first or second assembly component including the spacer may have a region carved therefrom adjacent to the spacer to define a cutout that reduces the thermal mass of the first or second assembly component. Thereby, heat transfer through the labyrinth seal can be reduced.

[0029] In some embodiments, the plurality of pump chambers include an inlet pump chamber on the inlet side of the pump assembly configured to receive process gas from a vacuum system, and at least one downstream pump chamber disposed between the inlet pump chamber and the outlet side of the pump assembly. The labyrinth seal further includes at least one gas pocket. The first and / or second assembly components include at least one gas flow path disposed to fluidly connect the at least one gas pocket to at least one of the downstream pump chambers. The at least one gas pocket can be at an equal pressure to the pump pressure of the downstream pump chamber.

[0030] Multiple pump chambers are chambers through which the pump's compression work acts on the process gas, thus defining multiple pump stages. Thus, the inlet pump chamber corresponds to the inlet stage of the pump assembly. At least one gas passage can communicate with some downstream pump chamber other than the inlet pump chamber. Therefore, at least one gas pocket can be maintained at a pressure corresponding to the pressure of the pump stage to which it is fluidically connected.

[0031] At least one gas pocket collects leaked gases that are advancing into the labyrinth seal from outside the pump assembly. The collected gases are supplied to their respective downstream pump chambers and removed from the pump assembly. This further contributes to the sealing effect of the labyrinth seal, while maintaining high vacuum efficiency of the pump assembly in the inlet pump chamber.

[0032] In certain other embodiments, the first and second sealing surfaces are planar. One of the first and second sealing surfaces includes at least one gas passage extending from the other to at least one downstream pump chamber among a plurality of pump chambers. In such embodiments, when the first and second sealing surfaces are clamped together, the labyrinth seal has two contacting planes, but the gas passage provides an intricate path for gas attempting to leak across the seal. This is because leaked gases advancing from outside the pump assembly are collected by the gas passage (which is at the same pressure as each downstream pump chamber) and removed from the pump assembly. This contributes to the sealing effect of the labyrinth seal, while maintaining high vacuum efficiency of the pump assembly in the inlet pump chamber.

[0033] Some embodiments further include a sacrificial seal component positioned between a first sealing surface and a second sealing surface. The sacrificial seal component is sacrificial in the sense that it helps seal the labyrinth seal and may require maintenance. The sacrificial seal component allows the first and second assembly components to be joined with less clamping force due to the sealing effect provided by the sacrificial seal component. The sacrificial seal component may be made of a metal that does not degrade when exposed to the hot gases or process gases in which the pump assembly operates.

[0034] In some embodiments, the first and second assembly components are selected from a list of components comprising a stator component, a thermal break plate, and a head plate.

[0035] For example, in a clamshell pump, an elastomer seal is typically found between the first and second stator components. It is desirable to remove such elastomer seals to reduce costs and improve the maintenance interval of the pump.

[0036] For example, in screw pumps, elastomer seals are typically found between the stator components and the head plate surrounding the multiple pump chambers. It is desirable to remove such elastomer seals to reduce costs and improve the maintenance interval of the pump.

[0037] Furthermore, in screw pumps, for example, an elastomer seal is found between the thermal break plate and either the stator component or the head plate component. It is desirable to remove such elastomer seals to reduce costs and improve the maintenance interval of the pump.

[0038] The removal of elastomer seals between components in the embodiments described herein is particularly relevant when the vacuum pump operates with process gases that may degrade the elastomer seals, or when one or more of the assembly components operate at temperatures that would degrade or melt the elastomer seals.

[0039] In a further aspect of the present invention, a vacuum pump is provided comprising the pump assembly described in any one of claims 1 to 13.

[0040] In a further aspect of the present invention, a method is provided for sealing a first assembly component to a second assembly component in a pump assembly for a vacuum pump, the method comprising: providing a first assembly component and a second assembly component of a pump assembly, the pump assembly having an inlet side and an outlet side and a plurality of pump chambers disposed between them; joining a first sealing surface of the first assembly component to a second sealing surface of the second assembly component, thereby providing a seal for substantially sealing the plurality of pump chambers from the outside of the pump assembly; the method further comprising the step of configuring the joining of the first sealing surface and the second sealing surface such that the seal includes a labyrinth seal.

[0041] Various features of the pump assemblies of this disclosure allow for the removal of elastomer seals from the pump assemblies. These include longitudinal seals that can be provided between each stator half in a clamshell pump, annular seals provided between the stator and head plate in a screw pump design, and seals provided between a thermal break plate and the stator or head plate.

[0042] In detail, the various features of the pump assemblies described herein allow for the elimination of the elastomer seal between the thermal break plate and the head plate of a screw pump, while maintaining the thermal break function between the plates and the performance of the screw pump. In practice, a screw pump design without any elastomer seal is provided.

[0043] The present invention will be described below merely illustratively with reference to the accompanying drawings. [Brief explanation of the drawing]

[0044] [Figure 1] An embodiment of a pump assembly for a screw pump is shown. [Figure 2A] Figure 1 shows one embodiment of a labyrinth seal that can be used in a screw pump. [Figure 2B] The labyrinth seal in Figure 2A is shown in more detail. [Figure 2C] The labyrinth seal in Figure 2A is shown in more detail. [Figure 3] Further embodiments of a labyrinth seal that can be used in the screw pump shown in Figure 1 are presented. [Figure 4] Further embodiments of a labyrinth seal that can be used in the screw pump shown in Figure 1 are presented. [Figure 5A] Further embodiments of a pump assembly for a screw pump are shown. [Figure 5B] Figure 5A shows one embodiment of a labyrinth seal that can be used in a screw pump. [Figure 6A] An embodiment of a labyrinth seal that provides interference fit is shown. [Figure 6B] Another embodiment of a labyrinth seal that provides interference fit is shown. [Figure 6C] Another embodiment of a labyrinth seal that provides interference fit is shown. [Figure 7] An embodiment of a labyrinth seal having a hollow raised section is shown. [Figure 8A] This shows one embodiment of a pump assembly that can be used in a clamshell / Roots design pump. [Figure 8B] The embodiment shown in Figure 8A is further illustrated. [Figure 9A] This shows one embodiment of the interface surfaces of the first and second stator components in a clamshell-designed pump. [Figure 9B] An embodiment of the labyrinth seal that can be used in the embodiment shown in Figure 9A is shown. [Figure 10] An embodiment of a method for sealing a first assembly component to a second assembly component in a pump assembly for a vacuum pump is shown. [Modes for carrying out the invention]

[0045] Figure 1 shows one embodiment of a pump assembly 100 for a screw pump type vacuum pump.

[0046] The pump assembly 100 comprises an inlet side 110 and an outlet side 120, and a plurality of pump chambers 130 located between them. The plurality of pump chambers 130 include seven pump chambers 131-137. The first pump chamber 131 is also known as the inlet pump chamber 131 and is located adjacent to the inlet side 110. The remaining pump chambers 132-137 are also known as the downstream pump chambers 132-137 and are located between the inlet pump chamber 131 and the outlet side 120. The volume of the pump chambers 131-137 decreases from the inlet side 110 to the outlet side 120.

[0047] The pump chamber 130 is defined within a housing between a first assembly component 140 that constitutes the stator of the pump assembly and a second assembly component 150 that constitutes the head plate of the pump assembly. The stator 140 has a first sealing surface 141, and the head plate 150 has a second sealing surface 151. The first and second sealing surfaces 141, 151 are arranged to be joined together to provide a seal (highlighted by the circled area 160) for substantially sealing the multiple pump chambers 130 from the outside 170 of the pump assembly 100. In the illustrated embodiment, the seal 160 will be formed on the radially outer edges of the stator 140 and the head plate 150. The seal 160 includes a labyrinth seal, as described later.

[0048] The pump chamber 130 itself is defined between the stator 140, the head plate 150, and the rotor 195, which is shown to extend along the pump shaft A, penetrating a housing defined between the stator 140 and the head plate 150. The rotor 195 comprises a rotor shaft 195a and a plurality of rotor blades 195b extending outward from the pump shaft A and defining the respective pump chambers 131-137. The rotor 195 may generally include two screw rotors, which interact with the pump chambers 131-137 to propel the process gas through the pump assembly from the inlet side 110 to the outlet side 120 (i.e., from the high vacuum side to the low vacuum side of the pump assembly 100). Thus, as illustrated, the plurality of pump chambers 130 are the chambers through which the compression work of the pump assembly 100 acts on the process gas.

[0049] The stator 140 is shown to have at least one gas passage 181, 182, 183 arranged to fluidly connect at least one gas pocket (invisible) of the seal 160 to at least one of the downstream pump chambers 132-137, the at least one gas pocket being able to be at the same pressure as the pump pressure in the downstream pump chambers 132-137. More specifically, two gas passages 181 and 182 are shown, connecting to pump chambers 133 and 135, respectively. The two gas passages 181 and 182 are each drilled through the stator 140 longitudinally (along axis A) for a distance corresponding to the distance from the inlet side 110 (high vacuum side) to the pump chambers 133 and 135. Next, the illustrated gas passages 181 and 182 are drilled through the stator 140 perpendicular to axis A and connected to pump chambers 133 and 135 (however, gas passages 181 and 182 can alternatively be drilled through the stator 140 and connected to any of the pump chambers 131-137). Furthermore, an additional gas passage 183 is shown to penetrate the stator 140 on the outlet side 120 (low vacuum side) and connect to pump chamber 137.

[0050] Also shown is a thermal break plate 190 that maintains thermal break between the stator 140 and the head plate 150. The thermal break plate 190 is bolted to the stator 140. In the illustrated pump assembly 100, the thermal break between the stator 140 and the head plate 150 is important because the stator 140 is configured to operate at a first temperature (e.g., 200°C) that is higher than a second temperature (e.g., below 100°C) at which the head plate 150 is configured to operate. It should be understood that the head plate 150 may have components of the pump assembly 100 whose operation is temperature sensitive, or may be in thermal contact with such components. For example, the head plate 150 may include bearings, seals, or oil that support the rotor 195 during operation.

[0051] Figure 2A shows one embodiment of a labyrinth seal 260 that can be used as the seal 160 of the pump assembly 100 in Figure 1. This figure is presented in cross-sectional view.

[0052] The labyrinth seal 260 is provided between the first sealing surface 241 of the stator 240 and the second sealing surface 251 of the head plate 250.

[0053] The labyrinth seal 260 comprises three consecutive ridges 261a, 261b, and 261c provided on the first sealing surface 241 of the stator 240. As illustrated, the ridges 261a-261c have a toothed cross-section.

[0054] The labyrinth seal 260 further comprises three consecutive grooves 262a, 262b, and 262c provided on the second sealing surface 251 of the head plate 250 for engaging with the raised portions 261a, 261b, and 261c.

[0055] Furthermore, a spacer 263 is positioned between the first and second sealing surfaces 241 and 251. The spacer 263 defines a gap 265 between the stator 240 and the head plate 250. The gap 265 can be 0.6 mm.

[0056] Gas passages 281 and 282 are also shown, which are arranged to fluidly connect gas pockets 264a and 264b to at least one downstream pump chamber of the pump assembly (for example, pump chambers 133 and 135 in Figure 1).

[0057] As illustrated, the operating temperature of the stator 240 is indicated as "200C," which means 200 degrees Celsius. The operating temperature of the headplate 250 is indicated as "80C," which means 80 degrees Celsius.

[0058] Next, referring to Figure 2B, which further explains the labyrinth seal 260 in Figure 2A, the intricate shape of the seal 260 becomes clear.

[0059] Figure 2B shows the stator component 240 and head plate 250 clamped together with bolts. Thus, the spacer 263 is sandwiched between the first sealing surface 241 of the stator component 240 and the second sealing surface 251 of the head plate 250. Although the spacer 263 is in thermal contact with both the first sealing surface 241 and the second sealing surface 251, heat transfer through the spacer 263 is suppressed because the spacer 263 is manufactured from a ceramic material with low thermal conductivity.

[0060] As is clear from Figure 2B, the gap 265 between the first and second contact surfaces 241 and 251 is maintained by the spacer 263. Also, as is clear from Figure 2B, the raised portion (e.g., 261a) fits (is received within) the groove (e.g., 262a) in a cooperative manner.

[0061] In a pump assembly equipped with a seal 260 (e.g., 170 in Figure 1), the seal 260 defines an intricate path from the outside 270 to the inside 230 (e.g., 130 in Figure 1). Gas attempting to leak through the seal 260 must bypass the raised portion 261a, pass through the groove 262a, through the gas pocket 264b, bypass the raised portion 261b, pass through the groove 262b, pass through the gas pocket 264a, bypass the raised portion 261c, and pass through the groove 262c. This intricate path and the fluid vortex it promotes help reduce the spread of leaked gas through the seal 260.

[0062] In addition, the interference fit between the raised portions 261a-c and the grooves 262a-c (highlighted by circle 266) further suppresses gas leakage and provides a robust interface between the stator 240 and the head plate 250.

[0063] Furthermore, gas pockets 264a and 264b are at the same pressure as the respective pump chambers to which they are connected by gas passages 281 and 282. This allows leaked gas to be removed from the pump assembly equipped with the labyrinth seal 260. For example, during use, the pressure in gas pocket 264a can be 10 mbar and the pressure in gas pocket 264b can be 200 mbar.

[0064] Next, with reference to Figure 2C, the interference fit 266 highlighted in Figure 2B will be described in more detail.

[0065] As illustrated using the example of the raised portion 261a, the raised portion 261a is sized to fit snugly into the groove 262a of the head plate 250. Interference fitting is provided on two sides 266a and 266b of the raised portion 261a. This minimizes gas leakage through the raised portion 261a while also minimizing the surface area of ​​the raised portion 261a that is in thermal contact with the head plate 250.

[0066] Figure 3 shows a further embodiment of the labyrinth seal 360 that can be used in the pump assembly 100 of Figure 1. In detail, the labyrinth seal 360 can be used on the outlet side 120 (low vacuum side) of the pump assembly 100.

[0067] This figure shows a stator component 340 and a head plate 350, with a spacer 363 positioned between them. In this embodiment 360, two ridges 361a and 361b having a toothed cross-section are shown protruding from the stator component 340. Cooperative grooves 362a and 362b of the head plate 350 for mating with the ridges 361a and 361b are also shown. A gas pocket 364 is located between the ridges 361a and 361b. The gas pocket 364 is shown to be fluidly connected to a gas passage 380. The gas passage 380 is connected to the downstream pump chamber of the pump assembly (e.g., the final pump chamber 137 in Figure 1).

[0068] Figure 4 shows a further embodiment of the labyrinth seal 460 that can be used in the pump assembly 100 of Figure 1. In this particular embodiment, the seal 460 can be used on the inlet side of the pump assembly.

[0069] As illustrated, the labyrinth seal 460 comprises a stator 440 and a head plate 450, with a spacer 463 positioned between them. Adjacent to (directly below) the spacer 463, a sacrificial component 467 is also shown. In addition to the gas pocket 464 and gas passage 480, the seal 460 comprises a plurality of ridges 461 and grooves 462, as described herein.

[0070] Spacer 463 defines the gap 465 as described above with respect to Figure 2A-2C. Sacrificial element 467 is larger in size than spacer 463 and is designed to be compressed between the stator 440 and the head plate 450 when the stator 440 and head plate 450 are clamped together. Sacrificial element 467 provides an additional sealing effect when in use. Although sacrificial element 467 is shown to have a circular cross-section, it may have other cross-sectional shapes. Sacrificial element 467 may be made of metal.

[0071] Advantageously, the presence of the sacrificial element 467 can reduce the clamping force required to clamp the stator 440, head plate 450, and spacer 463 together. This is because the sacrificial element 467 contributes to the sealing effect, reducing the leakage rate of the seal 460 to a desired level (e.g., 10⁻⁶ mbar l / s).

[0072] Figure 5A shows a further embodiment of the pump assembly 500 for a screw pump. The embodiment of the pump assembly 500 is the same as the pump assembly 100 shown in Figure 1, except for the labyrinth seal 560 circled in the figure. In this particular embodiment 500, the stator 540 is modified to include a notch (carving) 568 that integrates a spacer (invisible) and provides a thermal break.

[0073] Figure 5B further illustrates a labyrinth seal 560 that can be used with the pump assembly 500 of Figure 5A.

[0074] As illustrated, the spacer 563 is integrally formed with the stator 540. Thus, the spacer 563 resembles a projection from the first sealing surface 541 of the stator 540. The spacer 563 protrudes and defines a gap 565, which, when in use, provides a gap 565 between the first sealing surface 541 and the second sealing surface 551 of the head plate 550.

[0075] As can be seen from Figure 5B, during use, the spacer 563 will come into contact with the second sealing surface 551 of the head plate 550. Thus, the stator 540 and the head plate 550 will be in thermal contact. To reduce the possibility of heat transfer from the stator 540 to the head plate 550, the stator 540 is provided with a notch 568. The notch 568 can be continuous around the stator 540. This reduces the thermal conductivity near the interface between the stator 540 and the head plate 550.

[0076] The figures presented and described herein show specific cross-sectional shapes of the raised portions and grooves, but it should be understood that various different shapes can be used, which result in a labyrinth seal and provide the advantages of the present invention. Further embodiments are briefly described below.

[0077] Figure 6A shows a further embodiment of the cross-sectional shape of the labyrinth seal 660. As illustrated, the first assembly component 640 includes a raised portion 661 that provides interference fit into the groove 662 of the second assembly component 650.

[0078] Figure 6B shows a further embodiment of the cross-sectional shape of the labyrinth seal 660'. As illustrated, the first assembly component 640' includes a raised portion 661' that provides interference fit into the groove 662' of the second assembly component 650'.

[0079] Figure 6C shows a further embodiment of the cross-sectional shape of the labyrinth seal 660''. As illustrated, the first assembly component 640'' includes a ridge 661'' that provides interference fit into the groove 662'' of the second assembly component 650''.

[0080] Figure 7 shows a further embodiment of the labyrinth seal 760, which includes a hollow ridge 761. As shown in the cross-sectional view, the hollow ridge 761 resembles a hollow tooth formed by drilling holes in the ridge 761. The hollow ridge 761 of the first assembly component 740 helps to reduce the thermal conductivity between the ridge 761 and the groove 762 of the second assembly component 750. Furthermore, the ridge 761 can be slightly bent when inserted into the groove 762, facilitating the assembly of the seal 760.

[0081] While certain embodiments described herein relate to screw pumps and, more specifically, to the sealing of the stator and head plate, the full scope of the invention is not limited thereto. More specifically, the inventions disclosed herein can be applied to other pump designs and to sealing other assembly components together.

[0082] Figure 8A shows one embodiment of the pump assembly 800 that can be used in a clamshell design / Roots pump.

[0083] In a clamshell / Roots pump, the stator 840 comprises a first stator half 841 and a second stator half 842 joined together along an interface defined by the inner surfaces 841a and 842a of the stator halves. The joining of the stator halves 841 and 842 defines a housing that includes multiple pump chambers.

[0084] As illustrated, a thermal break plate 890 can be positioned between the stator 840 and the head plate 850. The thermal break plate 890 and the stator 840, as well as the thermal break plate 890 and the head plate 850, may require sealing with each other.

[0085] Figure 8B shows one embodiment of a labyrinth seal 860 that can be used with the pump assembly 800 of Figure 8A.

[0086] The labyrinth seal 860 is formed between the thermal break plate 890 and the head plate 850. The labyrinth seal 860 provides the illustrated ridges 861, grooves 862 and spacers 863, but the labyrinth seal 860 can take any form of the labyrinth seals 260, 360, 460, 560, 660, 660', 660'', and 760 as described herein. Furthermore, the gas passage 880 is perforated through the thermal break plate 890.

[0087] Figure 9A shows an embodiment 900 illustrating a seal 960 between a first stator component 941 and a second stator component 942 in a clamshell-designed pump assembly.

[0088] In the embodiment 900 shown in cross-section, a first stator component 941 (upper stator) is positioned on top of a second stator component 942 (lower stator) and defines a housing 995 for the rotor. The first and second stator components 941 and 942 are sealed to each other at their peripheries, and a seal 960 surrounds the housing 995 that houses the rotor. Conventionally, elastomer seals used for this purpose are called longitudinal seals because they are located in a plane parallel to the longitudinal axis of the rotor.

[0089] Figure 9B shows an embodiment of a labyrinth seal 960 that can be used in embodiment 900 of Figure 9A as an alternative to an elastomer seal.

[0090] The first stator component 941 and the second stator component 942 can be joined together using a labyrinth seal 960 having a raised portion 961 and a groove 962, as described herein with respect to any of the labyrinth seals 260, 360, 460, 560, 660, 660', 660'', and 760.

[0091] Figure 10 shows one embodiment of a method 1000 for sealing a first assembly component to a second assembly component in a pump assembly for a vacuum pump.

[0092] The first step 1001 includes providing first and second assembly components of a pump assembly, the pump assembly having an inlet side and an outlet side, and a plurality of pump chambers arranged between them.

[0093] A further step 1002 includes joining a first sealing surface of a first assembly component to a second sealing surface of a second assembly component, thereby providing a seal for substantially sealing a plurality of pump chambers from the outside of the pump assembly.

[0094] A further step 1003 includes configuring the joint of the first and second sealing surfaces such that the seal includes a labyrinth seal.

[0095] Certain embodiments described herein utilize spacers (e.g., ceramic spacers), but such spacers can be removed if a thermal break is not required between the first and second assembly components.

[0096] While certain embodiments suggest a precise number of ridges and grooves that form a labyrinth seal, any number of ridges and grooves can be utilized.

[0097] While not all specific embodiments are shown to include a sacrificial component within the labyrinth seal, this is not intended to be limiting. Sacrificial components can be used in any embodiment to reduce the requirement of clamping two assembly components together to a leak-free level.

[0098] While certain embodiments suggest precise cross-sections of the ridges or grooves, it should be understood that multiple different shapes and outlines of the ridges or grooves may be used. The ridges and grooves may differ from the illustrated cross-sections and may further extend around multiple pump chambers in a continuous manner that is not strictly annular.

[0099] While the embodiments illustrated may be described in a specific context for a particular pump type, it should be understood that the removal of elastomer seals and their replacement with labyrinth seals are applicable across a wide range of vacuum pumps, including Roots pumps, Roots claw pumps, screw pumps, and clamshell pumps.

[0100] The illustrated pump assembly may also reside in an additional enclosure filled with purge gas to control leaked gas.

[0101] It should be understood that a vacuum pump comprises other components known in the art, such as motors, bearings, and various housings.

[0102] Certain embodiments described herein include both raised sections and grooves, but embodiments of labyrinth seals including only raised sections or only grooves may also be utilized. For example, one sealing surface of an assembly component may be flat, while the other sealing surface includes either raised sections or grooves. Alternatively, a separable raised section may be located between the grooves of the first and second sealing surfaces. [Explanation of Symbols]

[0103] 100 pump assemblies 110 Entrance side 120 Exit side 130 Multiple pump rooms 131 Inlet Pump Room 132-137 Downstream Pump Room 140 First assembly component 141 First sealing surface 150 Second assembly component 151 Second sealing surface 160 Labyrinth Seals 170 External view of the pump assembly 181 Gas flow path 182 Gas flow path 183 Gas flow path 190 Thermal Break Plate 195 Rotor A pump shaft 230 Inside the pump assembly 240 stator 241 First sealing surface 250 Headplate 251 Second sealing surface 260 Labyrinth Seals 261a, b, c Continuous raised areas 262a, b, c Continuous grooves 263 Spacer 265 gap 281 Gas flow path 282 Gas flow path 264a, b Gas pocket 266 Interference Fitting 270 External parts of the pump assembly 340 Stator Components 350 Headplate 360 Labyrinth Seals 361a, b Continuous raised areas 362a, b Continuous grooves 363 Spacer 364 Gas Pocket 380 Gas flow path 440 stator 450 Headplate 460 Labyrinth Seals 461 Multiple consecutive raised areas 462 Multiple consecutive grooves 463 Spacer 464 Gas Pocket 465 gap 467 Sacrificial Components 480 Gas flow path 500 Pump Assembly 540 stata 541 First sealing surface 550 Headplate 551 Second sealing surface 560 Labyrinth Seals 563 Spacer 568 Notch 660, 660', 660'' Labyrinth Seal 640, 640', 640'' First assembly component 650, 650', 650'' Second assembly component 661, 661', 661'' ridge 662, 662', 662'' Groove 760 Labyrinth Seal 740 First assembly component 750 Second assembly component 761 Hollow ridge 762 Groove 800 Pump Assembly 840 stator 841 First stator hemisphere 841a Inner surface of the first stator half 842 Second stator hemisphere 842a Inner surface of the second stator half 850 Headplate 860 Labyrinth Seal 861 Ridge 862 Groove 863 Spacer 890 Thermal Break Plate 941 First stator component 942 Second stator component 960 Labyrinth Seal 961 Ridge 962 Groove 995 cabinet 1000 ways 1001 Steps to provide 1002 Joining step 1003 Steps to configure

Claims

1. A pump assembly for a vacuum pump, An inlet side and an outlet side, and a plurality of pump chambers arranged between the inlet side and the outlet side, A first assembly component defining a first sealing surface, and a second assembly component defining a second sealing surface, Equipped with, The first assembly component and the second assembly component are arranged to be joined together at the first sealing surface and the second sealing surface, thereby providing a seal for substantially sealing the plurality of pump chambers from the outside of the pump assembly. The seal is a pump assembly including a labyrinth seal.

2. The pump assembly according to claim 1, wherein the labyrinth seal comprises at least one continuous ridge provided on the first sealing surface and / or the second sealing surface, the at least one continuous ridge extending around the plurality of pump chambers.

3. The pump assembly according to claim 2, wherein the at least one continuous raised portion comprises at least one hollow raised portion.

4. The pump assembly according to claim 2 or 3, wherein the at least one continuous raised portion is separable from both the first sealing surface and the second sealing surface.

5. The pump assembly according to any one of claims 2 to 4, wherein the at least one continuous raised portion comprises a plurality of continuous raised portions.

6. The pump assembly according to any one of claims 2 to 5, wherein the labyrinth seal further comprises at least one continuous groove provided on the second sealing surface and / or the first sealing surface, the at least one continuous groove extending around the plurality of pump chambers to engage with the at least one continuous protrusion.

7. The pump assembly according to claim 6, wherein the at least one continuous groove provides interference fit to the at least one continuous protrusion.

8. The pump assembly according to claim 6 or 7, further comprising a spacer disposed between the first sealing surface and the second sealing surface, wherein the spacer defines a gap between the first component and the second component.

9. The pump assembly according to claim 8, wherein the spacer includes a projection extending from the first sealing surface or the second sealing surface.

10. The pump assembly according to claim 9, wherein the first assembly component or the second assembly component having the spacer is further provided with a notch positioned adjacent to the protrusion and providing a thermal break.

11. The plurality of pump chambers comprises an inlet pump chamber on the inlet side of the pump assembly, configured to receive process gas from a vacuum system, and at least one downstream pump chamber located between the inlet pump chamber and the outlet side of the pump assembly, and the labyrinth seal further comprises at least one gas pocket. The first assembly component and / or the second assembly component comprises at least one gas passage arranged to fluidly connect the at least one gas pocket to at least one of the downstream pump chambers, The pump assembly according to any one of claims 8 to 10, wherein the at least one gas pocket can be made equal in pressure with the pump pressure of the downstream pump chamber.

12. The pump assembly according to any one of claims 8 to 11, further comprising a sacrificial seal component disposed between the first sealing surface and the second sealing surface.

13. The first assembly component and the second assembly component are, Stator components and, Thermal break plate and Headplate and A pump assembly according to any one of claims 1 to 12, selected from a list of components comprising the above.

14. A vacuum pump comprising the pump assembly described in any one of claims 1 to 13.

15. A method for sealing a first assembly component to a second assembly component in a pump assembly for a vacuum pump, A step of providing a first assembly component and a second assembly component of a pump assembly, wherein the pump assembly has an inlet side and an outlet side, and a plurality of pump chambers disposed between the inlet side and the outlet side. A step of joining a first sealing surface of the first assembly component and a second sealing surface of the second assembly component, thereby providing a seal for substantially sealing the plurality of pump chambers from the outside of the pump assembly; The method includes, A method further comprising the step of forming a joint between the first sealing surface and the second sealing surface such that the seal includes a labyrinth seal.

Images