Stator for a vacuum pump
By integrating a pressure reduction system into the vacuum pump stator, the problems of excessive pressure differential and condensate contamination are solved, resulting in more efficient pumping and more stable operation, reducing the risk of rotor damage, and improving system reliability and ease of maintenance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EDWARDS LTD
- Filing Date
- 2022-04-29
- Publication Date
- 2026-07-10
AI Technical Summary
The pressure difference in the pumping chamber of the vacuum pump may be too high, which can damage the rotor, shaft and bearings. At the same time, the pressure reducing valve is located in the cold part and is easily contaminated by fluid condensate, which affects the stability of the system.
A pressure reducing system is integrated into the stator of the vacuum pump, including a channel and a pressure reducing valve. The channel connects the discharge side and the suction side of the pumping chamber, and the pressure reducing valve is located in the hotter part of the stator. It reduces the accumulation of condensate and protects critical components by controlling the pressure difference.
It effectively reduces the pressure difference on both sides of the rotor, lowers the risk of rotor damage, reduces condensate contamination, improves pumping efficiency and system stability, and facilitates maintenance and repair.
Smart Images
Figure CN117222814B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to stators and components thereof for vacuum pumps. Background Technology
[0002] Vacuum pumps are used in various technical processes to pump gases out of the processing chamber, thereby creating low-pressure conditions for the corresponding process. Summary of the Invention
[0003] The inventors have recognized that, during use, the pressure differential within the pumping chamber of a vacuum pump can reach or exceed levels that could damage components of the vacuum pump. For example, the pressure differential across the rotor between the suction and discharge sides of the pumping chamber can be high enough to damage the pump's rotor, shaft, and / or bearings. Therefore, a pressure-reducing system including a pressure-reducing valve for the pumping chamber is needed. The inventors have recognized that positioning the pressure-reducing valve in a relatively cold part of the pump (e.g., the head plate) exposes the pressure-reducing valve to the risk of contamination or damage from condensate from the pumped fluid. The inventors have recognized that by positioning the pressure-reducing valve in a relatively hot part of the pump (e.g., the stator wall), the amount of condensate can be reduced.
[0004] In one aspect, at least a portion of a stator for a vacuum pump is provided, the at least portion of the stator having an integral or integrated pressure reducing system including a pressure reducing valve.
[0005] In one aspect, at least a portion of a stator for a vacuum pump is provided, comprising: a plurality of walls defining at least a portion therebetween a pumping chamber; a channel formed within one or more of the plurality of walls, the channel including a first opening at a first end of the channel and a second opening at a second end of the channel, the first opening being an opening in an inner surface of the one or more walls and in fluid communication with the pumping chamber; and a pressure reducing valve disposed within the channel.
[0006] The first opening can be located on the discharge side of the pumping chamber.
[0007] The second opening can be an opening in the inner surface of one or more walls and is in fluid communication with the pumping chamber. The second opening can be located on the suction side of the pumping chamber.
[0008] The pressure reducing valve may be located in a housing that can be removed from at least a portion of the stator via an orifice in the outer surface of at least a portion of the stator.
[0009] Multiple walls may include end walls and one or more side walls extending from the end walls. The end walls and one or more side walls may define an inner cavity. Channels may be formed in the end walls. A first opening may be formed in the inner surface of the end wall. A second opening may be formed in the inner surface of the end wall. The end walls and one or more side walls may be an integral article. The end walls may include one or more through-holes, each of which is used to receive a corresponding rotor shaft. At least a portion of the stator for the vacuum pump may also include an inlet channel formed through one or more side walls for allowing fluid to flow from the outside of at least a portion of the stator into the inner cavity. The end walls may include an outer surface comprising one or more recesses. The one or more recesses may be selected from the group consisting of annular grooves for receiving O-rings and recesses configured to receive thermally insulating spacers. At least a portion of the stator may further include: an O-ring and / or one or more thermally insulating spacers disposed in the one or more recesses; and a head plate for supporting one or more rotor shafts, the head plate being disposed facing the outer surface of the end wall and abutting against the O-ring and / or one or more thermally insulating spacers, such that the head plate is spaced apart from the outer surface of the end wall.
[0010] In another aspect, a vacuum pump is provided, comprising: a stator including at least a portion of a stator according to any of the foregoing aspects; one or more rotor shafts extending through a pumping chamber of the stator; and one or more rotors, each rotor being mounted on a corresponding one of the rotor shafts. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the side view of a vacuum pump (not drawn to scale);
[0012] Figure 2 This is a schematic diagram of the front view of a vacuum pump (not drawn to scale);
[0013] Figure 3 This is a schematic diagram showing a perspective view of the stator of a vacuum pump (not drawn to scale);
[0014] Figure 4 This is a schematic diagram showing a perspective cross-section of the stator (not drawn to scale);
[0015] Figure 5 This is a perspective view of the first part of the stator (not drawn to scale);
[0016] Figure 6 This is a perspective view of the second part of the stator (not drawn to scale); and
[0017] Figure 7 This is a perspective view of the second part of the stator (not drawn to scale). Detailed Implementation
[0018] It should be understood that relative terms such as above and below, horizontal and vertical, top and bottom, front and back, etc., used in this document are merely for the convenience of referring to the accompanying drawings, and these terms are not so restrictive and can represent any two different directions or positions, etc., rather than literally above and below, horizontal and vertical, top and bottom, etc.
[0019] Figure 1 This is a schematic side view of an embodiment of the vacuum pump 100 (not drawn to scale).
[0020] Figure 2 This is a schematic diagram of the front cross-section of vacuum pump 100 (not drawn to scale).
[0021] Vacuum pump 100 is a vertically oriented Roots-type vacuum pump.
[0022] The vacuum pump 100 includes a stator 102, a first rotor 104 mounted to a first rotor shaft 106, a second rotor 108 mounted to a second rotor shaft 110, a first head plate 112, and a second head plate 114.
[0023] The stator 102 comprises two parts, namely the first stator part 116 and the second stator part 118. Figure 3 and Figure 4 An additional view of stator 102 is provided. Figure 3 This is a schematic diagram showing a perspective view of the stator 102 (not drawn to scale). Figure 4 This is a schematic diagram showing a perspective cross-sectional view of the stator 102 (not drawn to scale).
[0024] The first stator portion 116 and the second stator portion 118 can be considered as barrel stators, which are attached together to form stator 102.
[0025] The first stator portion 116 includes a first wall 120 and one or more first sidewalls 122 extending from the first wall 120. The first wall 120 can be considered as the bottom wall or first end wall of the stator 102. The one or more first sidewalls 122 extend upward from the first wall 120. The first wall 120 and the one or more first sidewalls 122 define an internal cavity. The first wall 120 and the one or more first sidewalls 122 can be a single, integral article.
[0026] The first stator portion 116 also includes an outlet passage 124. The outlet passage 124 is a gas outlet for the stator 102. The outlet passage 124 is formed through one or more of the first sidewalls 122. The outlet passage 124 is a passage between a first opening 126 and a second opening 128. The first opening 126 is located on the inner surface of one or more sidewalls 122. The second opening 128 may be located on the outer surface of one or more sidewalls 122, opposite to the inner surface of one or more sidewalls 122. Preferably, the outlet passage 124 slopes downward from the first opening 126 to the second opening 128.
[0027] The inner surface 130 of the first wall 120 is adjacent to the first opening 126 of the outlet channel 124. Preferably, the lowest point of the inner surface 130 of the first wall 120 is adjacent to the first opening 126. Preferably, the inner surface 130 of the first wall 120 slopes downward toward the first opening 126. However, in some embodiments, the inner surface 130 may be substantially flat.
[0028] The inner surface 130 of the first wall 120 can be considered as adjacent to the first opening 126, sharing a boundary with the first opening, connecting to the first opening, being connected to the first opening, or being consistent with the first opening. When viewed from the side, as... Figure 1 As shown, the lowermost surface 132 of the outlet channel 124 is substantially flush with, or more preferably lower than, the horizontal plane 134 of the inner surface 130 of the first wall 120. Furthermore, when viewed from the front, as... Figure 2 As shown, the inner surface 130 of the first wall 120 coincides with the periphery of the first opening 126, or more preferably is located in the area defined by the periphery of the first opening 126.
[0029] In this embodiment, the first wall 120 includes two through holes 136. Each through hole 136 receives a corresponding one of the first rotor shaft 106 and the second rotor shaft 110. In other words, the first rotor shaft 106 and the second rotor shaft 110 pass through the first wall 120 via the corresponding through hole 136. The first rotor shaft 106 and the second rotor shaft 110 can be sealed against the first wall 120 (i.e., the wall of the through hole 136) by any suitable sealing device (e.g., a lip seal or a labyrinth seal).
[0030] In this embodiment, the outer surface 138 of the first wall 120, opposite to the inner surface 130 of the first wall 120, includes a plurality of recesses. The outer surface 138 of the first wall 120 can... Figure 5 It is clearer in the middle that Figure 5 This is a schematic perspective view of the inverted first stator section 116 (not drawn to scale).
[0031] More specifically, in this embodiment, the outer surface 138 of the first wall 120 includes an annular recess or groove 140. The annular groove 140 surrounds the through hole 136. The annular groove 140 may be located near the peripheral edge of the outer surface 138.
[0032] In this embodiment, the outer surface 138 of the first wall 120 includes a plurality of recesses 142, which are substantially cylindrical in this embodiment. In this embodiment, the recesses 142 are disposed between the annular groove 140 and the edge of the outer surface 138.
[0033] Return to reference Figure 1 and Figure 2 In this embodiment, a first O-ring 144 is disposed in an annular groove 140 on the outer surface 138 of the first wall 120. The first O-ring 144 can be made of any suitable material, such as polytetrafluoroethylene (PTFE). Preferably, the first O-ring 144 is made of a thermally insulating material. Furthermore, in this embodiment, a plurality of first spacers 146 are respectively disposed in a plurality of recesses 142. The first spacers 146 can be generally cylindrical. In this embodiment, the first spacers 146 are made of a thermally insulating material such as ceramic.
[0034] The first head plate 112 is positioned facing or confronting the outer surface 138 of the first wall 120. The first head plate 112 is disposed against the first O-ring 144 and the first spacer 146. The first O-ring 144 and / or the first spacer 146 keep the first head plate 112 spaced apart from the outer surface 138 of the first wall 120. Thus, a gap 148 (e.g., an air gap) is provided between the stator 102 and the first head plate 112. The first O-ring 144 forms a seal between the stator 102 and the first head plate 112, that is, a seal is formed between the outer surface 138 of the first wall 120 and the facing surfaces of the first head plate 112.
[0035] The first head plate 112 is configured to support the first and second rotor shafts 106, 110 at their bottom ends. The first head plate may be a conventional head plate. The first head plate 112 may include bearings and / or sealing systems for supporting the rotor shafts 106, 110.
[0036] In this embodiment, one or more first sidewalls 122 include a first flange 150 at the end of the first sidewall 122 opposite to the first wall 120.
[0037] The second stator portion 118 includes a second wall 152 and one or more second sidewalls 154 extending from the second wall 152. The second wall 152 can be considered as the top wall or second end wall of the stator 102. The one or more second sidewalls 154 extend downward from the second wall 152. The second wall 152 and the one or more second sidewalls 154 define an internal cavity. The second wall 152 and the one or more second sidewalls 154 can be a single, integral article.
[0038] The second stator portion 118 also includes an inlet passage 155. The inlet passage 155 is a gas inlet for the stator 102. The inlet passage 155 is formed to pass through one or more of the second sidewalls 154.
[0039] In this embodiment, the second wall 152 includes two through holes 156. Each through hole 156 receives a corresponding one of the first rotor shaft 106 and the second rotor shaft 110. In other words, the first rotor shaft 106 and the second rotor shaft 110 pass through the second wall 152 via the corresponding through hole 156. The first rotor shaft 106 and the second rotor shaft 110 can be sealed against the second wall 152 (i.e., the wall of the through hole 156) by any suitable sealing device (e.g., a lip seal or a labyrinth seal).
[0040] In this embodiment, the outer surface 158 of the second wall 152 includes a plurality of recesses. The outer surface 158 of the second wall 152 can be... Figure 6 and Figure 7 It is clearer in the middle that Figure 6 and Figure 7 This is a perspective view of the second stator section 118 (not drawn to scale).
[0041] More specifically, in this embodiment, the outer surface 158 of the second wall 152 includes an annular recess or groove 160. The annular groove 160 surrounds the through hole 156. The annular groove 160 may be located near the peripheral edge of the outer surface 158.
[0042] In this embodiment, the outer surface 158 of the second wall 152 includes a plurality of recesses 162, which are substantially cylindrical in this embodiment. In this embodiment, the recesses 162 are disposed between the annular groove 160 and the edge of the outer surface 158.
[0043] Return to reference Figure 1 and Figure 2In this embodiment, a second O-ring 164 is disposed in an annular groove 160 on the outer surface 158 of the second wall 152. The second O-ring 164 can be made of any suitable material, such as polytetrafluoroethylene (PTFE). Preferably, the second O-ring 164 is made of a thermally insulating material. Furthermore, in this embodiment, a plurality of second spacers 166 are respectively disposed in a plurality of recesses 162. The second spacers 166 can be generally cylindrical. In this embodiment, the second spacers 166 are made of a thermally insulating material such as ceramic.
[0044] The second head plate 114 is positioned facing or confronting the outer surface 158 of the second wall 152. The second head plate 114 is disposed against the second O-ring 164 and the second spacer 166. The second O-ring 164 and / or the second spacer 166 keep the second head plate 114 spaced apart from the outer surface 158 of the second wall 152. Thus, a gap 168 (e.g., an air gap) is provided between the stator 102 and the second head plate 114. The second O-ring 164 forms a seal between the stator 102 and the second head plate 114, that is, a seal is formed between the outer surface 158 of the second wall 152 and the facing surfaces of the second head plate 114.
[0045] The second head plate 114 is configured to support the first and second rotor shafts 106, 110 at their tips. The second head plate 114 may be a conventional head plate. The second head plate 114 may include bearings and / or sealing systems for supporting the rotor shafts 106, 110.
[0046] In this embodiment, one or more second sidewalls 154 include a second flange 170 at the end of the second sidewall 154 opposite to the second wall 152.
[0047] In its assembly structure, such as Figures 1 to 4 As shown, the second stator portion 118 is positioned on the first stator portion 116 such that the second flange 170 contacts the first flange 150. The first stator portion 116 and the second stator portion 118 are attached together by a plurality of fasteners (not shown) that pass through the first and second flanges 150, 170.
[0048] The walls of the first stator portion 116 and the second stator portion 118 (i.e., the first wall 120, the first side wall 122, the second wall 152, and the second side wall 154) define an inner cavity or chamber 171. Chamber 171 may be referred to as a stator bore. This chamber 171 is the pumping chamber of the vacuum pump 100. Rotors 104 and 108 are located within chamber 171.
[0049] In operation, one or more motors (not shown) drive rotor shafts 106, 110, causing rotors 104, 108 to rotate about a parallel axis within chamber 171. This rotation of rotors 104, 108 draws gas into the intake side 172 of chamber 171 via inlet 155, as... Figure 1 As indicated by the arrows and reference numeral 174 in the figure. The continued rotation of rotors 104 and 108 then moves the gas from the intake side 172 of chamber 171 to the exhaust side 176 of chamber 171, as shown. Figure 1 As indicated by the arrows and reference numeral 178 in the figure. The continued rotation of rotors 104 and 108 then moves the gas from the exhaust side 176 of chamber 171 to outlet 124, as shown. Figure 1 The arrows and reference numeral 180 in the figure are shown.
[0050] Therefore, rotors 104 and 108 can be considered to divide chamber 171 into an intake side 172 (where inlet 155 is located) and an exhaust side 176 (where outlet 124 is located).
[0051] The fluid (e.g., gas) pumped by vacuum pump 100 may contain or carry liquid and / or particulate matter, such as dust. Furthermore, the pumped fluid may condense on the surfaces within chamber 171. The liquid and / or particulate matter tends to fall to the bottom of pumping chamber 171 due to gravity and may accumulate on the inner surface 130 of the first wall. Advantageously, the inner surface 130 of the first wall 120, adjacent to the first opening 126 of the outlet passage 124, tends to allow the liquid and / or particulate matter to flow out of the pumping chamber via the outlet 124 or travel outside the pumping chamber. The proximity of the lowest point of the inner surface 130 to the first opening 126 and / or the downward slope of the inner surface 130 towards the first opening 126 tends to further facilitate the discharge of liquid and / or removal of particulate matter from chamber 171.
[0052] Therefore, it is advantageous to reduce or eliminate the accumulation of potentially flammable, corrosive, or other hazardous liquids and / or particulate matter within the pumping chamber 171. Furthermore, it is advantageous to reduce or eliminate, for example, obstruction of the rotors 104 and 108 by liquids and / or particulate matter. Therefore, it is advantageous to improve the pumping efficiency of the pump.
[0053] Advantageously, the spatial separation between the stator 102 and the head plates 112, 114 via O-rings 144, 164 and spacers 146, 166 (i.e., gaps 148, 168 between the stator 102 and the head plates 112, 114) tends to reduce heat transfer between the stator 102 and the head plates 112, 114. Therefore, in embodiments where the temperature of the stator 102 is relatively high, the temperature of the head plates can still be kept relatively low. For example, in some embodiments, the temperature of the stator 102 may be about 200°C, while the temperature of the head plates 112, 114 may be about 100°C. This advantageously tends to improve the operation of the vacuum pump 100.
[0054] In this embodiment, the second stator portion 118 further includes a channel 182 formed within the second wall 152. The channel 182 extends between the first opening 184 and the second opening 186.
[0055] In this embodiment, a first opening 184 is formed in the inner surface 188 of the second wall 152, which is opposite to the outer surface 158. The first opening 184 is located at the discharge side 176 of the chamber 171.
[0056] In this embodiment, a second opening 186 is formed in the inner surface 188 of the second wall 152. The second opening 186 is located on the suction side 172 of the chamber 171.
[0057] In this embodiment, a pressure reducing valve 190 is disposed within a channel 182, between a first opening 184 and a second opening 186. In this embodiment, the pressure reducing valve 190 is configured to prevent fluid flow through the channel 182 if the pressure difference across the valve is less than a predetermined threshold (e.g., 1 bar). Furthermore, the pressure reducing valve 190 is configured to allow fluid flow through the channel 182 if the pressure difference across it is greater than or equal to the predetermined threshold.
[0058] Therefore, in this embodiment, during operation, if the pressure difference across the pressure reducing valve 190 (i.e., the pressure difference between the discharge side 176 and the suction side 172 of chamber 171) is greater than or equal to a predetermined threshold, the pressure reducing valve 190 opens to allow the pumped fluid to flow from the discharge side 176 of chamber 171 through passage 182 to the suction side 172 of chamber 171. This advantageously tends to reduce the pressure difference between the discharge side 176 and the suction side 172. In other words, the pressure difference across rotors 104, 108 is reduced. Therefore, the risk of damage to rotors 104, 108 is tended to be reduced.
[0059] Advantageously, a passage 182 fluidly connected between the discharge side 176 and the suction side 172 tends to provide a more rapid reduction in the pressure differential between the discharge side 176 and the suction side 172. However, in some embodiments, the passage 182 may be fluidly connected between the pumping chamber 171 (e.g., the discharge side 176 of chamber 171) and the external environment of the pump 100.
[0060] In this embodiment, the pressure reducing valve 190 is located within or is housed within the stator 102, particularly in the second wall 152 of the stator 102. The pressure reducing valve 190 can be considered integral with or integrated into the stator 102. In use, the temperature of the stator 102 tends to be relatively high compared to, for example, the temperatures of the head plates 112, 114. For example, in some embodiments, the temperature of the stator 102 may be about 200°C, while the temperature of the head plates 112, 114 may be about 100°C. The relatively high temperature of the stator 102 tends to reduce or eliminate condensation of the pumped fluid within the passage 182. This advantageously tends to reduce or eliminate condensation that hinders the operation of the pressure reducing valve 190.
[0061] In this embodiment, the pressure reducing valve 190 is located in the housing and can be removed from the stator via an orifice in the side of the second end wall 152. This advantageously facilitates the inspection, maintenance, care, and / or repair of the pressure reducing valve 190.
[0062] Advantageously, by positioning the pressure reducing valve 190 in the upper part of the stator, i.e., in the top wall, any particulate matter or fluid that does enter the channel 182 will tend to fall out of the channel 182 (i.e., the pressure reducing valve pipe) rather than accumulate.
[0063] In some embodiments, channel 182 is a multi-branched channel (e.g., a double-branched channel) having a plurality of first openings (or inlets) and / or a plurality of second openings (or outlets). In some embodiments, a plurality of pressure-reducing valves may be located in the channel.
[0064] In the above embodiments, the vacuum pump is a vertically oriented Roots-type vacuum pump. However, in other embodiments, the vacuum pump is of a different type. The vacuum pump can have, for example, any number of stages, pumping chambers, rotors, and rotor shafts.
[0065] In the above embodiments, the stator is formed of two parts that are attached together to form the stator. However, in other embodiments, the stator is formed of a different number of parts, such as a single part or more than two parts that are attached together to form the stator.
[0066] In the above embodiments, the inlet is formed in the second stator portion. However, in other embodiments, the inlet is located in different stator portions, such as the first stator portion. In some embodiments, the inlet is formed to pass through multiple different stator portions.
[0067] In the above embodiments, the two head plates are spaced apart from the stator. However, in other embodiments, one or more of the head plates are not spaced apart from the stator. For example, one or more of the head plates may contact the stator or may be integral with the stator.
[0068] In the above embodiment, the second stator portion includes a channel in which the pressure-reducing valve is located. However, in other embodiments, the channel and the pressure-reducing valve located therein may be located in different portions of the stator, such as the first stator portion, like the first wall.
[0069] In the above embodiments, the outlet is formed in the first stator portion. However, in other embodiments, the outlet is located in a different stator portion, such as a second stator portion. In some embodiments, the outlet is formed to pass through multiple different stator portions.
[0070] In the above embodiment, the inner surface of the first wall of the first stator is adjacent to the opening of the outlet channel. In other words, the lowest surface or point of the opening is substantially flush with or below the inner surface of the first wall. However, in other embodiments, the inner surface of the first wall of the first stator is not adjacent to the opening of the outlet channel. The lowest surface or point of the opening may be located at a horizontal plane above the horizontal plane of the inner surface of the first wall.
[0071] Figure Labels
[0072] 100-Vacuum Pump
[0073] 102-Stator
[0074] 104-First Rotor
[0075] 106-First rotor shaft
[0076] 108-Second Rotor
[0077] 110-Second Rotor Shaft
[0078] 112 - First Board
[0079] 114 - Second Headboard
[0080] 116-First Stator Section
[0081] 118 - Second Stator Section
[0082] 120 - First Wall
[0083] 122-First sidewall
[0084] 124-Exit Channel
[0085] 126 - First Opening
[0086] 128-Second Opening
[0087] 130-Inner Surface
[0088] 132-lower surface
[0089] 134-Horizontal plane
[0090] 136-Through Hole
[0091] 138 - Outer Surface
[0092] 140- Annular Groove
[0093] 142-concave
[0094] 144 - First O-ring
[0095] 146-First Spacer
[0096] 148-gap
[0097] 150-First flange
[0098] 152-Second Wall
[0099] 154-Second sidewall
[0100] 155 - Entrance Passage
[0101] 156-Through Hole
[0102] 158 - Outer Surface
[0103] 160- Annular Groove
[0104] 162-concave
[0105] 164 - Second O-ring
[0106] 166-Second Spacer
[0107] 168-gap
[0108] 170-Second flange
[0109] 171-chamber
[0110] 172-Inhalation side
[0111] 174 - Direction of Inhaled Gas Flow
[0112] 176-Discharge side
[0113] 178 - Gas Flow Direction
[0114] 180-Exhaust gas flow direction
[0115] 182-Channel
[0116] 184 - First Opening
[0117] 186-Second Opening
[0118] 188-Inner Surface
[0119] 190-Pressure reducing valve
Claims
1. A stator for a vertically oriented vacuum pump, comprising: A plurality of walls, wherein the plurality of walls define at least a portion therebetween a pumping chamber; A channel formed within one or more of the plurality of walls, the channel including a first opening at a first end of the channel and a second opening at a second end of the channel, the first opening being an opening in the inner surface of the one or more walls, the first opening being in fluid communication with the pumping chamber; as well as A pressure reducing valve is disposed within the channel. The plurality of walls include: Top wall; and One or more sidewalls extending downward from the top wall, wherein the top wall and the one or more sidewalls define an internal cavity. in: The channel is formed in the top wall; The first opening is formed in the inner surface of the top end wall, and the second opening is formed in the inner surface of the top end wall; The first opening is located on the discharge side of the pumping chamber; The second opening is located on the suction side of the pumping chamber; The top wall includes one or more through holes, each of which is used to receive a corresponding rotor shaft; and The top wall and the one or more side walls are a single, integral item.
2. The stator according to claim 1, wherein, The pressure reducing valve is located in the housing and can be removed from the stator via an orifice in the outer surface of the stator.
3. The stator according to claim 1 or 2, further comprising an inlet channel formed through one or more of the sidewalls for allowing fluid to flow from the outside of the stator into the inner cavity.
4. The stator according to claim 1 or 2, wherein, The top wall includes an outer surface, and the outer surface of the top wall includes one or more recesses.
5. The stator according to claim 4, wherein, The one or more recesses are selected from the group consisting of: annular grooves for receiving O-rings and recesses configured to receive thermally insulating spacers.
6. The stator according to claim 4, further comprising: O-rings and / or one or more thermally insulating spacers, wherein the O-rings and / or the one or more thermally insulating spacers are disposed in the one or more recesses; and A head plate for supporting one or more rotor shafts, the head plate being configured to face the outer surface of the top end wall and abut against the O-ring and / or the one or more thermally insulating spacers, such that the head plate is spaced apart from the outer surface of the top end wall.
7. A vertically oriented vacuum pump, comprising: Stator according to any one of claims 1 to 6; One or more rotor shafts, the one or more rotor shafts extending vertically through the pumping chamber of the stator; as well as One or more rotors, each rotor being mounted on a corresponding one of the rotor shafts.