vacuum pump

Abstract

The vacuum pump comprises a pump assembly (110), an inlet means (120), an outlet means (130), and a housing (140) for housing the pump assembly (110), the housing (140) comprising a first end portion (141), a second end portion (142), and a sleeve means (143) positioned between the first end portion (141) and the second end portion (142), the sleeve means (143) comprising a bellows means (143a) for adapting to the thermal expansion of the vacuum pump (100).

Description

Technical Field

[0001] The field of the present invention relates to vacuum pumps, and more particularly to vacuum pumps comprising a "seal-free" pump assembly.

Background Art

[0002] Vacuum pumps are generally used as components of a vacuum system for exhausting the 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 the 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] Examples of vacuum pumps include claw pumps and screw pumps, both of which are examples of multi-stage pumps. Generally, the pump assembly of a claw pump needs to use two stator shell halves and two end plates (also called head 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. The pump assembly of a screw pump comprises two cooperating screw rotors housed within a stator having an inlet and an outlet. The stator abuts an end plate (also called a head plate) to effectively seal the 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 the annular seal therebetween.

[0004] 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.

[0005] Even at low temperatures, removing elastomer seals can offer desirable benefits such as reduced vacuum pump costs, less need for frequent service intervals, and a longer overall lifespan. However, removing elastomer seals to provide a "seal-free" pump may increase the leakage of process gases from the pump assembly to the external environment in which the vacuum pump is located. Furthermore, gases such as oxygen may leak from the external environment into the pump assembly. This becomes a problem if the pump assembly is emitting process gases that can react with oxygen (i.e., if the process gases contain hydrogen).

[0006] The method discussed in International Publication No. 2023 / 001718 is to provide a safety device that surrounds at least the stator element of a vacuum pump and forms a containment volume for the pressurized gas. Another method discussed in British Patent No. 2118904.8 is to provide a housing around the entire seal-free pump assembly of a vacuum pump, which can be filled with an inert purge gas.

[0007] However, specific embodiments of practical implementations of housings for vacuum pumps have not yet been addressed. More specifically, thermal expansion of components may occur during the operation of a vacuum pump. This can occur in the pump assembly itself, the head plate, the upper and lower covers of the vacuum pump, or in the inlet and outlet pipes that can transport and / or process heated process gases. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2023 / 001718 [Patent Document 2] British Patent No. 2118904.8 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, it is desirable to provide a vacuum pump that mitigates these problems. [Means for solving the problem]

[0010] In one embodiment, a vacuum pump is provided, the vacuum pump comprising: a pump assembly having an inlet and an outlet, the pump assembly comprising stator means and rotor means arranged to define at least one pump chamber between the inlet and the outlet, the rotor means rotating around a pump shaft in use and arranged to discharge process gas from the inlet to the outlet; inlet means for connecting the inlet to a first external piping of the vacuum pump assembly, the inlet means allowing process gas to flow into the pump assembly from the first external piping; outlet means for connecting the outlet to a second external piping of the vacuum pump assembly, the outlet means allowing process gas to flow out of the pump assembly to the second external piping; and a housing for housing the pump assembly, the housing comprising a first end portion, a second end portion, and a sleeve means arranged between the first end portion and the second end portion, the sleeve means comprising bellows means for accommodating thermal expansion of the vacuum pump.

[0011] Vacuum pump assemblies, particularly those without elastomer seals (also known as "seal-free vacuum pumps"), can be prone to gas leaks both inside and outside the pump assembly. This raises safety concerns in applications where process gases (gases expelled by the vacuum pump) may react with gases from the external environment leaking into the pump assembly. An example of such a process gas is hydrogen, which can react with oxygen leaking into the pump assembly. This gas leak and the associated risks contradict the safety specifications of the vacuum pump.

[0012] The inventors recognize, in British Patent No. 2118904.8, incorporated herein by reference, that a solution to such problems is to provide a “seal-free” vacuum pump assembly within a further airtight seal environment, i.e., within a further enclosure. The invention described herein helps to provide a practical design for such an enclosure that takes into account the operating conditions of the vacuum pump, helps to be applied to any vertically or horizontally positioned vacuum pump, and further helps to minimize the impact on the current occupied area of ​​the vacuum pump design. More specifically, the enclosure provided by the invention comprises bellows means that help to accommodate the thermal expansion of the vacuum pump (i.e., can accommodate the thermal expansion of one or more components of the vacuum pump).

[0013] In some embodiments, the sleeve means comprises a first sleeve extending continuously from a first end portion to a second end portion in a direction parallel to the pump shaft. Providing a first sleeve extending from a first end portion to a second end portion of the housing helps to enable easy assembly of the vacuum pump with a minimum number of housing components. More specifically, the pump assembly and other components of the vacuum pump can be incorporated "inside" the housing, and the sleeve slides over or is positioned on the pump assembly and other components. For example, the motor, head plate, stator, and rotor can be positioned on the first or second end portion, with the first sleeve sliding over the components and the second or first end portion positioned on the first sleeve.

[0014] In some embodiments, the bellows means includes a first bellows positioned as at least part of a first sleeve, the first bellows extending in a direction parallel to the pump axis. The first bellows can be considered integrally formed with the first sleeve and can extend partially or entirely along the first sleeve in the direction of the pump axis. For example, in some embodiments, the first sleeve can be formed entirely of a bellows structure. This allows for greater adaptation to the thermal expansion of the vacuum pump or one or more of its components.

[0015] In some embodiments, the inlet and outlet means include inlet and outlet pipes, respectively, which extend through either a first end portion, a second end portion, or a first sleeve. The inlet and outlet pipes may extend through the same or different portions of the housing to connect to external piping that supplies process gas to the pump assembly. This allows the process gas to reach the pump assembly, which is located and sealed within the housing of the vacuum pump.

[0016] In some embodiments, the inlet and / or outlet pipes extend through a first sleeve, and the bellows means comprises a second bellows projecting from the first sleeve and surrounding the inlet and / or outlet pipes. The inlet and / or outlet pipes can be used to transfer heated gas to and from the pump assembly of a vacuum pump. By providing a second bellows projecting from the first sleeve around the inlet and / or outlet pipes, the housing can accommodate thermal expansion in the vicinity of the inlet and / or outlet pipes.

[0017] In some embodiments, the second bellows is attached to the first sleeve using an end face seal, preferably an elastomer end face seal. The end face seal helps to reduce leakage at the joint between the first sleeve and the second bellows in the radial direction with respect to the axis of the seal. Elastomer end face seals tend to be preferred because they are less expensive, reusable during assembly and disassembly, and require relatively low clamping force compared to, for example, metal seals.

[0018] In some embodiments, the second bellows is attached to the inlet and / or outlet pipes using a metal seal. The metal seal helps to provide a seal that can withstand high temperatures.

[0019] In some embodiments, the second bellows is made of stainless steel. Using stainless steel for the second bellows has the advantage of low thermal conductivity, which helps to achieve a thermal break effect.

[0020] In some embodiments, the inlet pipe extends through an inlet channel provided at a first or second terminal portion, the outer diameter of the inlet pipe is smaller than the inner diameter of the inlet channel, and a first gap is provided between the outer surface of the inlet pipe and the inner surface of the inlet channel, and / or the outlet pipe extends through an outlet channel provided at a first or second terminal portion, the outer diameter of the outlet pipe is smaller than the inner diameter of the outlet channel, and a second gap is provided between the outer surface of the outlet pipe and the inner surface of the outlet channel.

[0021] Inlet and outlet pipes extending through the first and / or second end portions may result in direct contact between the inlet and / or outlet pipes and the first and / or second end portions. This may provide a path for heat transfer, i.e., heat loss, from the inlet and / or outlet pipes to the first and / or second end portions. In a vacuum pump, this can lead to condensation of process gases in the inlet and / or outlet pipes, potentially affecting the discharge efficiency of the vacuum pump. The first and / or second gaps act as thermal gaps to prevent overheating of the first and / or second end portions. This reduces the risk of process gas condensation, but also reduces the risk of overheating of the first and / or second end portions (and the components installed or housed within them). In other words, the housing can be thermally isolated not only from the pump assembly itself but also from the inlet and outlet pipes.

[0022] In some embodiments, a first purge gas passage is provided at the first and / or second end portion, and the first purge gas passage fluidly connects the first and / or second gap to a first purge gas supply unit for supplying the first purge gas. In some embodiments, the first purge gas is an inert gas. In some embodiments, the first purge gas is nitrogen.

[0023] The first gap and / or the second gap provide a potential path for gas to leak in and out of the housing. The first gap and / or the second gap may form a tortuous path (i.e., a labyrinth seal) for such gas leakage, but by supplying a first purge gas to the first gap and / or the second gap, gas leakage can be further reduced. This helps to ensure that the first gap and / or the second gap are filled with positive pressure against the gas that tries to leak into the housing from the environment outside the vacuum pump. By supplying the first purge gas as an inert gas, there are no safety concerns even if the first purge gas leaks into the housing and potentially into the pump assembly. In other words, the inert gas does not react with the process gas discharged by the pump assembly. Using nitrogen as the process gas tends to have the advantage of being a relatively low-cost and widely available inert gas.

[0024] Some embodiments further include at least two piston rings disposed in the first gap and / or the second gap, and the first purge gas flow path is fluidly connected to the first gap and / or the second gap at a position between the at least two piston rings.

[0025] The at least two piston rings provide a tortuous path for the gas that tries to leak into the housing from outside the vacuum pump. Further, the at least two piston rings minimize the contact surface between the first end portion and / or the second end portion and the inlet pipe and / or the outlet pipe. Thereby, heat transfer is minimized. By supplying the first purge gas between the at least two piston rings, the first purge gas is substantially confined between the piston rings within the gas pocket. This reduces the leakage of the first purge gas into the housing and / or outside the vacuum pump while maintaining the tortuous labyrinth seal between the inlet pipe and / or the outlet pipe and the first end portion and / or the second end portion.

[0026] In some embodiments, the sleeve means comprises a third sleeve extending in a direction parallel to the pump shaft from the first end portion to the first protruding rim of the stator means, and a fourth sleeve extending in a direction parallel to the pump shaft from the second end portion to the first protruding rim of the stator means, the inlet means and the outlet means extend through the first protruding rim for connection to the first external pipe and the second external pipe of the vacuum pump assembly, the bellows means is arranged as at least part of the third sleeve and comprises a third bellows extending in a direction parallel to the pump shaft, and / or is arranged as at least part of the fourth sleeve and comprises a fourth bellows extending in a direction parallel to the pump shaft.

[0027] In certain designs of the vacuum pump and its pump assembly, the stator itself includes the inlet means and the outlet means. For example, the inlet means and the outlet means may be embedded in / cast into the stator and protrude therefrom. In such a stator design, the sleeve means can necessarily be formed from two sleeves, one sleeve extending from one end portion of the housing to the rim and the other sleeve extending from the other end portion to the rim. In these embodiments, since the inlet means and the outlet means do not need to pass through the housing itself, it is possible to avoid the difficulty of sealing the housing around the inlet means and the outlet means. Thus, the housing can be easily manufactured as two sleeve parts, one or both of which include bellows for accommodating thermal expansion.

[0028] In some embodiments, the third and fourth sleeves are attached to the respective first end portion and second end portion using an end face seal, preferably an elastomeric end face seal. The end face seal serves to reduce leakage at the junction of the first sleeve and the second bellows in a direction radial to the axis of the seal. The elastomeric end face seal has a preference because it is, for example, of low cost, reusable during assembly and disassembly, and requires a relatively low clamping force as compared with a metal seal.

[0029] In some embodiments, the first end portion includes a recess for housing at least one of the following: the motor of the vacuum pump, a cooling means for the motor of the vacuum pump, one or more electrical cables for the vacuum pump, and other piping for the vacuum pump. This allows for a more compact vacuum pump design and integration of the vacuum pump components with the housing.

[0030] In some embodiments, the second end portion is the upper cover of the vacuum pump, and the upper cover has a second protruding rim for attachment to the sleeve means. Vacuum pumps traditionally have an upper cover. By providing a protruding rim on the upper cover (i.e., extending the upper cover), the housing can be incorporated into the vacuum pump structure without requiring additional cover parts. This helps reduce the number of additional components that make up the housing, simplifying manufacturing and lowering manufacturing costs.

[0031] Some embodiments further include a second purge gas supply passage provided at the first and / or second end portions, the second purge gas supply passage fluidly connecting the internal volume of the housing to the second purge gas supply section in order to supply the second purge gas. In some embodiments, the second purge gas is an inert gas. In some embodiments, the second purge gas is nitrogen.

[0032] By supplying a second purge gas to the housing itself, the pump assembly is further protected from external gases leaking into the pump assembly. This is because the second purge gas provides positive pressure within the housing relative to the outside of the vacuum pump. By selecting an inert gas for the second purge gas, the risk associated with the second purge gas leaking into the pump assembly is also reduced (i.e., inert gases tend not to react with process gases discharged by the pump assembly). The choice of nitrogen has the advantage of being a widely available and relatively low-cost inert gas. The second purge gas supply can be attached, for example, to the first and / or second end portions.

[0033] In a more preferred embodiment, a pressure sensor may be placed within the internal volume of the housing to monitor the pressure inside the housing. The pressure sensor may be electrically connected to a second purge gas supply unit to regulate the supply of a second purge gas.

[0034] In a more preferred embodiment, a one-way valve can be provided in either the first end portion, the second end portion, or the sleeve means to discharge the internal volume of the housing to the outside of the vacuum pump when the second purge gas supply unit is in use (i.e., when the internal volume is filled with the second purge gas).

[0035] A further aspect of the present invention provides a method for manufacturing a vacuum pump, the method comprising: preparing a pump assembly having an inlet and an outlet, the pump assembly comprising stator means and rotor means arranged to define at least one pump chamber between the inlet and the outlet, the rotor means being arranged to rotate around a pump shaft in use to discharge process gas from the inlet to the outlet; positioning the pump assembly on a first end portion of a housing to house the pump assembly; positioning a sleeve means of the housing on the first end portion, thereby surrounding the pump assembly, the sleeve means comprising bellows means for accommodating the thermal expansion of the vacuum pump; positioning a second end portion of the housing on the sleeve means, thereby surrounding the pump assembly; positioning an inlet means and an outlet means and fluidly connecting the inlet and the outlet to first and second external piping of the vacuum pump assembly, respectively, such that process gas can flow into the pump assembly from the first external piping and process gas can flow out of the pump assembly to the second external piping.

[0036] A further aspect of the present invention provides a method for sealing piping to the housing of a vacuum pump, the method comprising the steps of: preparing a flow path that penetrates the housing of a vacuum pump, wherein the flow path has an inner diameter greater than the outer diameter of a pipe; arranging a conduit in the flow path and extending through the housing such that a gap is provided between the inner surface of the flow path and the outer surface of the pipe; and supplying a purge gas to the gap.

[0037] Some embodiments further include the steps of providing at least two piston rings positioned in a gap and supplying a purge gas to the position between the at least two piston rings.

[0038] It should be understood that certain features of different embodiments of the present invention are useful in sharing the technical effects and advantages of corresponding features of other embodiments of the present invention. More specifically, the methods described herein share the same technical advantages as the vacuum pumps described herein.

[0039] Furthermore, please understand that the use of terms such as "first" and "second" is merely intended to help distinguish similar features, and does not indicate that one feature is relatively more important than another, unless otherwise specified.

[0040] The present invention will be described below merely illustratively with reference to the accompanying drawings. [Brief explanation of the drawing]

[0041] [Figure 1A] A first embodiment of a vacuum pump is shown. [Figure 1B] Figure 1A shows a cross-sectional view of the outlet pipe extending through the housing of the vacuum pump. [Figure 1C] Figure 1A shows a further cross-sectional view of the outlet pipe extending through the housing of the vacuum pump. [Figure 2A] A second embodiment of the vacuum pump is shown. [Figure 2B] Figure 2A shows a partial view of the vacuum pump 200. [Figure 3] A third embodiment of the vacuum pump is shown. [Figure 4] One embodiment of a method for manufacturing a vacuum pump is shown. [Figure 5] One embodiment of a method for sealing a pipe to the housing of a vacuum pump is shown. [Modes for carrying out the invention]

[0042] Figure 1A shows a first embodiment of the vacuum pump 100 according to the present invention as described herein. The vacuum pump 100 is shown in a partial cross-sectional view.

[0043] The vacuum pump 100 comprises a pump assembly 110 having an inlet 111 and an outlet 112. The pump assembly 110 itself comprises a stator means 113 (i.e., a stator) and a rotor means (i.e., a rotor) positioned between head plates 114 and 115 to define at least one pump chamber between the inlet 111 and the outlet 112. The rotor means (invisible) is positioned to rotate around the pump shaft "A" when in use, discharging process gas from the inlet 111 to the outlet 112. The pump assembly 110 is a "seal-free" pump assembly. In other words, the pump assembly 110 does not have an elastomer seal such as an O-ring or gasket between the stator 113 and the head plates 114 and 115. Therefore, the pump assembly 110 may be prone to gas leakage into the pump assembly 110.

[0044] The vacuum pump 100 further includes an inlet means 120 for connecting the inlet 111 to a first external piping (not shown in the figure) of the vacuum pump assembly (not shown in the figure). This allows process gas to flow from the first external piping into the pump assembly 110.

[0045] The vacuum pump 100 further includes an outlet means 130 for connecting the outlet 112 to a second external piping (not shown in the figure) of the vacuum pump assembly (not shown in the figure). This allows the process gas to flow out of the pump assembly 110 into the second external piping.

[0046] Furthermore, the vacuum pump 100 includes a housing 140 in which the pump assembly 110 can be assembled and housed. For example, the pump assembly 110 can be assembled vertically within the housing 140. The housing 140 includes a first end portion 141, a second end portion 142, and a sleeve means 143 positioned between the first end portion 141 and the second end portion 142. The sleeve means 143 includes a bellows means 143a for accommodating the thermal expansion of the vacuum pump 100.

[0047] The first end portion 141 constitutes the base in which the motor 150 of the vacuum pump 100 is housed. Peripheral equipment 160, such as a cooling device for the motor 150 and electrical cables, is also housed in the first end portion 141, either embedded in the first end portion 141 or passing through the first end portion 141 to the exterior 170 of the vacuum pump 100. Any interface between the peripheral equipment 160 and the casing 170 is sealed using piston rings. The pump assembly 110 is connected to the first end portion 141, for example, by bolts 183 that pass through the head plate 113.

[0048] The second end portion 142 includes the upper cover of the vacuum pump 100. The second end portion 142 is enlarged to include a protruding rim 142a for attachment to the sleeve means 143. Thus, the upper cover of the vacuum pump 100 also functions as the upper part or cover of the housing 140.

[0049] The sleeve means 143 consists of a single sleeve (i.e., only the first sleeve) that extends continuously from a first end portion 141 to a second end portion 142 in a direction parallel to the pump shaft "A". The bellows means 143a is arranged as at least a part of the first sleeve and consists of a single bellows (i.e., the first bellows) that extends in a direction parallel to the pump shaft "A". The sleeve means 143 is attached to the first end portion 141 and the second end portion 142 using elastomer face seals 181 and 182.

[0050] In this embodiment of the vacuum pump 100, the inlet means 120 and outlet means 130 include the respective inlet and outlet pipes 120, 130. Thus, as described herein, the reference figures 120, 130 will also be used to directly refer to the inlet and outlet pipes 120, 130. The inlet pipe 120 extends through the second end portion 142. The outlet pipe 130 extends through the first end portion 141.

[0051] The inlet pipe 120 is connected by passing through the second end portion 142 using a piston seal 183. The outlet pipe 130 is connected by passing through the first end portion 141 using a seal configuration 184, as will be described in more detail later with reference to Figures 1B and 1C. However, the positions of the inlet pipe 120 and the outlet pipe 130 are changeable (i.e., either one can pass through the first end portion 141 or the second end portion 142).

[0052] The housing 140 hermetically seals the pump assembly 110 from the outside 170 of the vacuum pump 100. The housing 140 defines an internal volume V that is filled with nitrogen as the purge gas (however, some other inert gas can be used). Nitrogen is supplied into the housing 140 via a purge gas supply passage 190 provided at the second end portion 142. A purge gas supply device (not shown) can be attached to the second end portion 142. Furthermore, a pressure sensor (not shown) can be placed inside the housing 140 to regulate the flow of nitrogen through the supply passage 190. Also, a one-way valve (not shown) can be equipped at either the first end portion 141 or the second end portion 142 to help evacuate the housing 140 to the outside 170 while the housing 140 is being filled with nitrogen purge gas.

[0053] The housing 140 itself includes a pump stand 195 for enabling the pump to be deployed vertically (as shown in the figure) or horizontally. The pump stand 195 can be fixed to the first end portion 141 and the second end portion 142. For example, the pump 100 can be assembled in a vertical configuration and then rotated horizontally (as shown in the figure) for deployment.

[0054] In the illustrated vacuum pump 100, it will be understood that during use, process gas enters the inlet 111 of the pump assembly 110 through the inlet pipe 120. The pump assembly 110 discharges the process gas to the outlet 112, and then discharges it out of the vacuum pump 100 through the outlet pipe 130. To prevent gas from leaking from the outside 170 of the vacuum pump 100 into the pump assembly 110, the housing 140 is filled with nitrogen purge gas. This creates positive pressure inside the housing 140 to prevent gas leakage into the housing 140, but also ensures that any gas leakage into the pump assembly 110 is contained only by inert nitrogen gas. Furthermore, the bellows 143a ensure that the housing 140 can adapt to the thermal expansion of the vacuum pump 100 during use.

[0055] This is because the housing 140 is isolated from the high-temperature pump assembly 110 and outlet pipe 130 so as not to come into direct contact with them. The seals 181 and 182 of the illustrated housing 140 can be low-temperature seals such as elastomer seals.

[0056] Figure 1B shows a cross-sectional view of the outlet pipe 130 of Figure 1A, which extends through the housing 140 of Figure 1A. More specifically, Figure 1B shows a sealing mechanism 184 provided between the outlet pipe 130 and the housing 140.

[0057] The outlet pipe 130 is shown to extend through the outlet channel 184a provided at the first end portion 141. The outer diameter of the outlet pipe 130 is configured to be smaller than the inner diameter of the outlet channel 184a. This creates a gap 184b between the outer surface of the outlet pipe 130 and the inner surface of the outlet channel 184a.

[0058] Figure 1C shows a further cross-sectional view of the outlet pipe 130 that extends through the housing 140 in Figure 1A. The cross-sections shown in Figures 1B and 1C are perpendicular to each other.

[0059] The outlet pipe 130 extends through the outlet channel 184a provided at the first end portion 141. A gap 184b is shown between the outer surface of the outlet pipe 130 and the inner surface of the outlet channel 184a.

[0060] The purge gas passage 184c is provided at the first terminal portion 141 and, in this embodiment, fluidically connects the gap 184b to a purge gas supply unit (not shown) for supplying purge gas, which is nitrogen. Two piston rings 184d are positioned in the gap 184b. The purge gas passage 184c is fluidically connected to the gap 184b at a position between the two piston rings 184d.

[0061] As shown in Figure 1C, the purpose of the sealing mechanism 184 is to avoid direct contact between the outlet pipe 130 and the first end portion 141. The only contact occurs via the piston ring 184d. This provides a thermal gap, i.e., helps to reduce heat transfer between the outlet pipe 130 and the first end portion 141. This helps to prevent heat from the hot exhaust gas heating the outlet pipe 130 from being transferred to the first end portion 141, resulting in condensation of the exhaust gas within the outlet pipe 130. This helps to improve the exhaust efficiency of the vacuum pump 100 in Figure 1A. As a further benefit, this also helps to reduce the external temperature of the first end portion 141 to exceed safety limits (i.e., by preventing heat transfer to the end portion 141, the end portion 141 can be kept relatively cool, especially if the end portion 141 is touchable / may come into contact with a user). The presence of purge gas between the two piston rings 184d reduces gas leakage into the housing 140 in Figure 1 and further helps prevent process gas from leaking out of the housing 140. The gap 184b also helps prevent thermal overload of components that can be placed / housed within the first end portion 141.

[0062] Figure 2A shows a second embodiment of the vacuum pump 200. The vacuum pump 200 is shown in a partial cross-sectional view.

[0063] The vacuum pump includes the same pump assembly 210 as the pump assembly 110 shown in Figure 1A. The pump assembly 210 may reach a temperature of approximately 400°C during operation.

[0064] The vacuum pump 200 includes a housing 240 in which a pump assembly 210 can be assembled and housed. The housing 240 includes a first end portion 241, a second end portion 242, and a sleeve means 243 positioned between the first end portion 241 and the second end portion 242. The sleeve means 243 includes a bellows means 243a for accommodating the thermal expansion of the vacuum pump 200.

[0065] The first end portion 241 constitutes a base for housing the motor 250 and peripheral equipment 260, as described above for Figure 1A. The pump assembly 210 is coupled to the first end portion 241 in the same manner as described above for Figure 1A. The second end portion 242 includes the upper cover of the vacuum pump 200, as described above for Figure 1A. The sleeve means 243 includes a straight sleeve attached to the first end portion 241 via a piston seal 282. Thus, the pump 200 can adapt to any movement of the sleeve means 243 relative to the first end portion 241. The piston seal 282 can be an expansion seal, i.e., an O-ring with a relatively large cross-section (e.g., having a cross-section of 10-15 mm). The sleeve means 243 is attached to the second end portion 242 using an end face seal 281.

[0066] The vacuum pump 200 comprises an inlet means 220 and an outlet means 230. The inlet means 220 and the outlet means 230 include inlet and outlet pipes 220, 230, respectively. Thus, as described herein, the reference figures 220, 230 will also be used to directly refer to the inlet and outlet pipes 220, 230. The inlet pipe 220 extends through the sleeve means 243. The outlet pipe 230 extends through the sleeve means 243.

[0067] The inlet pipe 220 is attached to the sleeve means 243 using a piston seal 221. The outlet pipe 230 passes through the bellows means 243a. More specifically, the bellows means 243a includes a bellows that protrudes from the sleeve means 243 and surrounds the outlet pipe 230. The bellows of the bellows means 243a is attached to the sleeve means 243 using an elastomer or polymer end face seal 243b. The bellows of the bellows means 243a is attached to the outlet pipe 230 using a metal seal 243c. The bellows of the bellows means 243a is made of stainless steel, i.e., a material with low thermal conductivity.

[0068] As illustrated, the sleeve means 243 comprises a straight jacket sleeve that can be formed primarily from metal. This allows the majority of the sleeve means 243 to be manufactured at low cost. The sleeve means 243 adapts to thermal expansion during use of the vacuum pump 200 by providing a bellows means 243a surrounding the outlet pipe 230. The bellows means 243a will be described in more detail below with reference to Figure 2B.

[0069] Furthermore, a pump stand 295 is provided according to Figure 1A.

[0070] Figure 2B shows a partial view of the vacuum pump 200 shown in Figure 2A. In this partial view, the pump assembly 210, the first end portion 241, the second end portion 242, and the sleeve means 243 are shown in a simplified form.

[0071] The outlet pipe 230 extends from the pump assembly 210 to the outside 270 of the vacuum pump 200. The bellows means 243a protrudes from the sleeve means 243 and surrounds the outlet pipe 230. The polymer end face seal 243b connects the bellows means 243a to the sleeve means 243. The metal seal 243c connects the bellows means 243a to the outlet pipe 230. Thus, the internal volume V' is airtightly sealed from the outside 270, and the bellows means 243a can adapt to the thermal expansion of the vacuum pump 200.

[0072] The internal volume V' is filled with nitrogen as the purge gas according to Figure 1A (however, other inert gases can also be used).

[0073] Figure 3 shows a third embodiment of the vacuum pump 300. The vacuum pump 300 is shown in a cross-sectional view.

[0074] The vacuum pump 300 includes a pump assembly 310 that operates similarly to the pump assembly 110 in Figure 1A. More specifically, the pump assembly 310 includes a stator means 311.

[0075] Furthermore, the vacuum pump 300 includes a housing 340 in which a pump assembly 310 can be assembled and housed. The housing 340 includes a first end portion 341, a second end portion 342, and a sleeve means 343 positioned between the first end portion 341 and the second end portion 342. The sleeve means 343 includes a bellows means for accommodating the thermal expansion of the vacuum pump 300. The sleeve means 343 and the bellows means are described below.

[0076] The sleeve means 343 includes a third sleeve 343' that extends in a direction parallel to the pump shaft "B" of the pump assembly 310. The third sleeve 343' extends from the first end portion 341 to the first protruding rim 311a (i.e., flange) of the stator means 311.

[0077] Furthermore, the sleeve means 343 includes a fourth sleeve 343'' that extends in a direction parallel to the pump axis "B" from the second end portion 342 to the first protruding rim 311a of the stator means 311.

[0078] The vacuum pump 300 includes an inlet means 320 and an outlet means 330. The inlet means 320 and the outlet means 330 extend through a first protruding rim 311a to connect to a first external piping (not shown) and a second external piping (shown) of a vacuum pump assembly (not shown).

[0079] The bellows mechanism includes a third bellows 343a' positioned as at least a portion of the third sleeve 343' and extending in a direction parallel to the pump shaft "B". The bellows mechanism also includes a fourth bellows 343a'' positioned as at least a portion of the fourth sleeve 343'' and extending in a direction parallel to the pump shaft "B".

[0080] The third and fourth sleeves 343', 343'' are shown to be attached to the first and second end portions 341 and 342, respectively, using elastomer end seals 381, 382. The end seals 381, 382 can be some kind of low-temperature seal. The third and further sleeves 343', 343'' are further attached to the protruding rim 311a using high-temperature metal seals 383, 384. A pump stand 395 is also provided according to Figure 1A.

[0081] Therefore, the internal volume V'' is airtightly sealed from the outside 370, and the bellows means can adapt to the thermal expansion of the vacuum pump 300.

[0082] The internal volume V'' is filled with nitrogen as the purge gas according to Figure 1A (however, other inert gases can also be used).

[0083] The vacuum pump 300 tends to have the advantage that the inlet means 320 and outlet means 330 do not need to pass through the sleeve means 343. This avoids difficult sealing and makes the geometry of the housing 340 relatively simple. The bellows 343a' and 343a'' adapt to the tolerances in the design of the housing 340 and the thermal expansion of the vacuum pump 300 during use.

[0084] Figure 4 shows one embodiment of method 400 for manufacturing a vacuum pump.

[0085] The first step 410 includes preparing a pump assembly having an inlet and an outlet, the pump assembly including stator means and rotor means arranged to define at least one pump chamber between the inlet and the outlet, the rotor means being arranged to rotate around the pump shaft in use and to discharge process gas from the inlet to the outlet.

[0086] A further step 420 includes positioning the pump assembly on the first end portion of the housing to accommodate the pump assembly.

[0087] A further step 430 includes positioning a sleeve means of the housing on the first end portion to surround the pump assembly, the sleeve means comprising a bellows means for accommodating the thermal expansion of the vacuum pump.

[0088] A further step 440 includes positioning the second end portion of the housing on the sleeve means, thereby surrounding the pump assembly.

[0089] A further step 450 includes arranging inlet and outlet means to fluidly connect the inlet and outlet to a first external piping and a second external piping of the vacuum pump assembly, respectively, so that the process gas can flow into the pump assembly from the first external piping and the process gas can flow out of the pump assembly to the second external piping.

[0090] Figure 5 shows one embodiment of method 500 for sealing piping to the housing of a vacuum pump.

[0091] The first step 510 includes preparing a flow path that penetrates the housing of the vacuum pump, the flow path having an inner diameter larger than the outer diameter of the pipe.

[0092] A further step 520 includes positioning the piping within the flow path and extending it through the housing, so as to provide a gap between the inner surface of the flow path and the outer surface of the piping.

[0093] A further step 530 includes supplying purge gas to the gap.

[0094] While certain embodiments described herein indicate a specific number of seals between different components of a vacuum pump, this is not intended to be limiting. More or fewer seals may be used.

[0095] The specific embodiments described herein show different configurations between inlet and outlet means, or between inlet and outlet pipes, but these configurations are actually interchangeable.

[0096] The specific embodiments described herein may show specific components of a vacuum pump housed in a first or second end portion, but other components, such as other purge piping, cooling piping, power piping, cabling, controllers, etc., may be housed therein.

[0097] In this specification, nitrogen is referred to as the preferred inert gas, but any other inert gas may be used. [Explanation of Symbols]

[0098] 100 Vacuum pump 110 Pump Assembly 111 Entrance 112 Exit 113 Stator means 114, 115 Headplate 120 Inlet means / inlet pipe 130 Exit means / exit pipe 140 cabinets 141 First terminal portion 142 Second terminal section 142a Second protruding rim 143 Sleeve method 143a Bellows means 150 motor 160 Peripherals 170 External of a vacuum pump 181, 182 End face seals 183 Piston seal 184 Outlet pipe seal 184a Outlet channel 184b Gap 184c Purge gas channel 184d Piston Ring 190 Gas supply lines 195 Pump Stand 200 Vacuum pump 210 Pump Assembly 220 Inlet means / inlet pipe 221 Piston seal 230 Exit means / exit pipe 240 cabinets 241 First terminal portion 242 Second terminal section 243 Sleeve method 243a Bellows means 243b End seal 243c Metal seal 250 motor 260 Peripherals 281 End face seal 282 Piston seal 295 Pump Stand V, V', V'' Internal volume of the enclosure A, B pump shafts 300 Vacuum Pump 310 Pump Assembly 311 Stator means 311a First protruding rim 320 Entrance means 330 Means of exit 340 cabinets 341 First terminal portion 342 Second terminal portion 343 Sleeve method 343' Third Sleeve 343'' The fourth sleeve 343a' Third bellows 343a'' Fourth bellows 370 External of a vacuum pump 381, 382 End face seals 383, 384 Metal seals 400 ways 410-450 Method Steps 500 ways 510-530 Method Steps

Claims

1. It is a vacuum pump. A pump assembly having an inlet and an outlet, wherein the pump assembly comprises a stator means and a rotor means arranged to define at least one pump chamber between the inlet and the outlet, and the rotor means is arranged to rotate around the pump shaft during use and to discharge process gas from the inlet to the outlet, An inlet means for connecting the inlet to the first external piping of the vacuum pump assembly, wherein the process gas can flow into the pump assembly from the first external piping; An outlet means for connecting the aforementioned outlet to a second external piping of the vacuum pump assembly, wherein the process gas flows out from the pump assembly to the second external piping; A housing for housing the pump assembly, Equipped with, The aforementioned enclosure is The first terminal portion and The second terminal portion, A sleeve means positioned between the first end portion and the second end portion, A vacuum pump comprising, wherein the sleeve means comprises bellows means for adapting to the thermal expansion of the vacuum pump.

2. The vacuum pump according to claim 1, wherein the sleeve means includes a first sleeve that extends continuously in a direction parallel to the pump shaft from the first end portion to the second end portion.

3. The vacuum pump according to claim 2, wherein the bellows means includes a first bellows disposed as at least a portion of the first sleeve, the first bellows extending in a direction parallel to the pump shaft.

4. The vacuum pump according to any one of claims 2 to 3, wherein the inlet means and the outlet means each include an inlet pipe and an outlet pipe, and the inlet pipe and the outlet pipe extend through either the first end portion, the second end portion, or the first sleeve.

5. The vacuum pump according to claim 4, wherein the inlet pipe and / or outlet pipe extends through the first sleeve, and the bellows means comprises a second bellows protruding from the first sleeve and surrounding the inlet pipe and / or outlet pipe.

6. The second bellows is attached to the first sleeve using an end seal, preferably an elastomer end seal. The second bellows is attached to the inlet pipe and / or the outlet pipe using a metal seal, and / or The aforementioned second bellows is made of stainless steel. The vacuum pump according to claim 5.

7. The inlet pipe extends through the inlet passage provided in the first or second end portion, the outer diameter of the inlet pipe is smaller than the inner diameter of the inlet passage, and a first gap is provided between the outer surface of the inlet pipe and the inner surface of the inlet passage, and / or The outlet pipe extends through the outlet passage provided in the first or second end portion, the outer diameter of the outlet pipe is smaller than the inner diameter of the outlet passage, and a second gap is provided between the outer surface of the outlet pipe and the inner surface of the outlet passage. The vacuum pump according to claim 4.

8. The vacuum pump according to claim 7, further comprising a first purge gas passage provided in the first end portion and / or the second end portion, wherein the first purge gas passage fluidly connects the first gap and / or the second gap to a first purge gas supply unit for supplying the first purge gas, and the first purge gas is preferably an inert gas, and more preferably nitrogen.

9. The vacuum pump according to claim 8, further comprising at least two piston rings disposed in the first gap and / or the second gap, wherein the first purge gas passage is fluidly connected to the first gap and / or the second gap at a position between the at least two piston rings.

10. The aforementioned sleeve means is A third sleeve extending in a direction parallel to the pump shaft from the first end portion to the first protruding rim of the stator means, A fourth sleeve extending in a direction parallel to the pump shaft from the second end portion to the first protruding rim of the stator means, Equipped with, The inlet means and the outlet means extend through the first protruding rim to connect to the first external piping and the second external piping of the vacuum pump assembly, The vacuum pump according to claim 1, wherein the bellows means comprises a third bellows disposed as at least a part of the third sleeve and extending in a direction parallel to the pump shaft, and / or a fourth bellows disposed as at least a part of the fourth sleeve and extending in a direction parallel to the pump shaft.

11. The vacuum pump according to claim 10, wherein the third sleeve and the fourth sleeve are attached to the first and second end portions, respectively, using end face seals, preferably elastomer end face seals.

12. The first terminal portion is The motor of the vacuum pump, The cooling means for the motor of the vacuum pump, One or more electrical cables of the vacuum pump, Other piping of the aforementioned vacuum pump, A vacuum pump according to any one of claims 1 to 11, comprising a recess for accommodating at least one of the following.

13. The vacuum pump according to any one of claims 1 to 12, wherein the second end portion is an upper cover of the vacuum pump, and the upper cover comprises a second protruding rim for attachment to the sleeve means.

14. The vacuum pump according to any one of claims 1 to 13, further comprising a second purge gas supply passage provided in the first and / or second end portion, wherein the second purge gas supply passage fluidly connects the internal volume of the housing to the second purge gas supply section in order to supply the second purge gas, and the second purge gas is preferably an inert gas, and more preferably nitrogen.

15. A method for manufacturing a vacuum pump, A step of preparing a pump assembly having an inlet and an outlet, wherein the pump assembly comprises a stator means and a rotor means arranged to define at least one pump chamber between the inlet and the outlet, the rotor means being arranged to rotate around the pump shaft during use and to discharge process gas from the inlet to the outlet, To house the pump assembly, the step is to place the pump assembly on the first end portion of the housing, A step of positioning a sleeve means of the housing at a first end portion so as to surround the pump assembly, wherein the sleeve means includes a bellows means for adapting to the thermal expansion of the vacuum pump, The steps include: placing the second end portion of the housing on the sleeve means, thereby surrounding the pump assembly; A step of arranging the inlet means and the outlet means to fluidly connect the inlet and the outlet to the first external piping and the second external piping of the vacuum pump assembly, respectively, wherein the process gas can flow into the pump assembly from the first external piping and the process gas can flow out of the pump assembly to the second external piping. Methods that include...

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