Vacuum pump stator

Abstract

At least a portion of a stator (116) for a vacuum pump (100) comprises a first wall (120); one or more side walls (122) extending therefrom, the first wall (120) and the one or more side walls (122) defining an interior cavity; and an outlet passage (124) formed through the one or more side walls (122), the outlet passage (124) having an opening (126) in an inner surface of the one or more side walls (122), the outlet passage (124) allowing fluid to flow from the interior cavity to an exterior of at least a portion of the stator (116). The inner surface of the first wall (120) is continuous with the opening (126). Thus, liquid and particulate matter within at least a portion of the stator will tend to flow out of the stator through the outlet passage (124) by gravity.

Description

[Technical Field]

[0001] The present invention relates to a stator for a vacuum pump and components thereof. [Background technology]

[0002] Vacuum pumps are used in various technological processes to pump gases out of process chambers, thereby creating low-pressure conditions for the respective process.

[0003] It is known to orient vacuum pumps vertically, which tends to reduce the footprint of the vacuum pump compared to horizontally oriented vacuum pumps. Summary of the Invention [Means for solving the problem]

[0004] The inventors have recognized that liquids and particulate matter, such as dust, may be present in the fluid (e.g., gas) being pumped by a vacuum pump. In some processes, this liquid and / or particulate matter may be flammable, corrosive, or otherwise hazardous. This liquid and / or particulate matter may also interfere with the proper operation of the pump, such as by interfering with the rotation of the pump rotors. For this reason, it is undesirable for this liquid and particulate matter to accumulate within the pump.

[0005] Thus, a self-draining or passively draining vacuum pump stator is provided. Advantageously, liquid and other debris that collects within the pump stator will tend to flow away from the pump stator without the need for a sump or active liquid removal means to collect and remove the liquid.

[0006] In one aspect, at least a portion of a stator for a vacuum pump is provided, the stator including: a first wall; one or more sidewalls extending upward from the first wall, the one or more sidewalls defining an interior chamber; and an outlet passage formed through the one or more sidewalls, the outlet passage having an opening on an interior surface of one of the one or more sidewalls for allowing fluid to flow from the interior chamber out of at least a portion of the stator. The interior surface of the first wall is continuous with the opening of the outlet passage. In other words, the opening of the outlet passage is flush with the interior surface of the first wall or below a horizontal plane of the interior surface of the first wall. Thus, liquid within at least a portion of the stator tends to flow out of the stator through the outlet passage due to gravity, along with any particulate matter.

[0007] The lowest point of the inner surface of the first wall can be continuous with the opening of the outlet channel. The outlet channel can extend from the opening of the outlet channel in a direction having a downward component. The inner surface of the first wall can be inclined toward the opening or can be substantially flat. In other words, the inner surface of the first wall can be inclined downward toward the opening.

[0008] The first wall may include one or more through bores, each of the one or more through bores for receiving a respective rotor shaft.

[0009] The first wall can have an outer surface opposite the inner surface, and the outer surface of the first wall can include one or more recesses selected from the group of recesses consisting of a loop-shaped groove for receiving an O-ring and a recess (which can be substantially cylindrical) configured to receive an insulating spacer.

[0010] In a further aspect, a stator for a vacuum pump is provided, the stator comprising: a first stator portion that is a portion of the stator according to any of the above aspects; and a second stator portion. The second stator portion comprises a second wall and one or more additional side walls extending downwardly from the second wall. The one or more side walls of the first stator portion are attached to the one or more additional side walls of the second stator portion such that the first wall, the one or more side walls, the second wall, and the one or more additional side walls define an internal chamber. The stator further comprises an inlet passage formed through the one or more side walls or a side wall of the one or more additional side walls, the inlet passage allowing fluid to flow from outside the stator into the internal chamber.

[0011] The second wall may include one or more through bores, each of the one or more through bores for receiving a respective rotor shaft.

[0012] The second wall can have an outer surface, and the outer surface of the second wall can include one or more recesses. The one or more recesses in the outer surface of the second wall can include one or more recesses selected from the group of recesses consisting of: a loop-shaped groove for receiving an O-ring, and a recess (which can be substantially cylindrical) configured to receive an insulating spacer.

[0013] The stator may further include a pressure relief valve disposed within either the first wall or the second wall. The stator may further include a flow path formed within either the first wall or the second wall. The flow path may include a first opening located at a first end of the flow path and a second opening located at a second end of the flow path. At least one of the first opening or the second opening of the flow path may be formed on an inner surface of either the first wall or the second wall. The pressure relief valve may be disposed within the flow path.

[0014] In a further aspect, a vacuum pump is provided, comprising a stator according to any of the above aspects, one or more rotor shafts extending through an internal chamber of the stator between a first wall and a second wall, and one or more rotors, each rotor attached to a respective one of the rotor shafts.

[0015] The one or more rotors may define a suction side of the internal chamber and an exhaust side of the internal chamber. The stator may further include a flow passage formed in either the first wall or the second wall. The flow passage may include a first opening located at a first end of the flow passage and a second opening located at a second end of the flow passage. The first opening of the flow passage may be formed in an inner surface of either the first wall or the second wall at the exhaust side of the internal chamber. The second opening of the flow passage may be formed in an inner surface of either the first wall or the second wall at the suction side of the internal chamber. The vacuum pump may further include a pressure relief valve disposed in the flow passage.

[0016] The first wall may have an outer surface, the outer surface of the first wall having one or more recesses formed therein. The vacuum pump may further include a first O-ring and / or a first insulating spacer disposed in the one or more recesses formed in the outer surface of the first wall, and a first head plate for supporting the one or more rotor shafts, the first head plate positioned opposite the outer surface of the first wall and in contact with the first O-ring and / or the first insulating spacer, and the first head plate is spaced from the outer surface of the first wall.

[0017] The second wall may have an outer surface, the outer surface of the second wall having one or more recesses formed therein. The vacuum pump may further include a second O-ring and / or a second insulating spacer disposed in the one or more recesses formed in the outer surface of the second wall, and a second head plate for supporting the one or more rotor shafts, the second head plate positioned opposite the outer surface of the second wall and in contact with the second O-ring and / or the second insulating spacer, and the second head plate is spaced from the outer surface of the second wall. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram (not to scale) of a cross-sectional side view of a vacuum pump; [Figure 2] FIG. 1 is a schematic diagram (not to scale) of a front cross-sectional view of a vacuum pump. [Figure 3] FIG. 1 is a schematic diagram (not to scale) showing a perspective view of a stator of a vacuum pump. [Figure 4] FIG. 1 is a schematic diagram (not to scale) showing a perspective cross-sectional view of a stator. [Figure 5] FIG. 2 is a schematic diagram (not to scale) showing a perspective view of a first portion of a stator. [Figure 6] FIG. 10 is a schematic diagram (not to scale) showing a perspective view of a second portion of the stator. [Figure 7] FIG. 10 is a schematic diagram (not to scale) showing a perspective view of a second portion of the stator. DETAILED DESCRIPTION OF THE INVENTION

[0019] It should be understood that relative terms such as above and below, horizontal and vertical, top and bottom, front and back, etc. are used herein merely to facilitate reference to the drawings, and that these terms are not so limited and may embody any two different directions or positions, etc., rather than truly above and below, horizontal and vertical, top and bottom, etc.

[0020] FIG. 1 is a schematic diagram (not to scale) of a side cross-sectional view of one embodiment of a vacuum pump 100.

[0021] FIG. 2 is a schematic diagram (not to scale) of a front cross-sectional view of vacuum pump 100.

[0022] The vacuum pump 100 is a vertically oriented Roots type vacuum pump.

[0023] The vacuum pump 100 comprises a stator 102, a first rotor 104 mounted on a first rotor shaft 106, a second rotor 108 mounted on a second rotor shaft 110, a first head plate 112, and a second head plate 114.

[0024] The stator 102 comprises two parts: a first stator part 116 and a second stator part 118. Figures 3 and 4 show further views of the stator 102. Figure 3 is a schematic diagram (not to scale) showing a perspective view of the stator 102. Figure 4 is a schematic diagram (not to scale) showing a perspective cross-sectional view of the stator 102.

[0025] First stator portion 116 and second stator portion 118 can be considered bucket stators that are attached together to form stator 102 .

[0026] The first stator portion 116 includes a first wall 120 and one or more first side walls 122 extending from the first wall 120. The first wall 120 may be considered a bottom wall or a first end wall of the stator 102. The one or more first side walls 122 extend upwardly from the first wall 120. The first wall 120 and the one or more first side walls 122 define an interior cavity. The first wall 120 and the one or more first side walls 122 may be a single, unitary element.

[0027] The first stator portion 116 further 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 side walls 122. The outlet passage 124 is a flow path between a first opening 126 and a second opening 128. The first opening 126 is located on the inner surface of one or more of the side walls 122. The second opening 128 can be located on the outer surface of one or more of the side walls 122, opposite the inner surface of the one or more side walls 122. Preferably, the outlet passage 124 slopes downward from the first opening 126 to the second opening 128.

[0028] The inner surface 130 of the first wall 120 is continuous with the first opening 126 of the outlet channel 124. Preferably, the lowest point of the inner surface 130 of the first wall 120 is continuous with the first opening 126. Preferably, the inner surface 130 of the first wall 120 slopes downward toward the first opening 126. Nevertheless, in some embodiments, the inner surface 130 can be substantially flat.

[0029] The inner surface 130 of the first wall 120 can be considered to abut, share a border, join, connect, or coincide with the first opening 126. When viewed from the side, as in Figure 1, the bottom surface 132 of the outlet channel 124 is substantially flush with, or more preferably below, a horizontal plane 134 of the inner surface 130 of the first wall 120. And when viewed from the front, as in Figure 2, the inner surface 130 of the first wall 120 coincides with, or more preferably is within the area bounded by, the periphery of the first opening 126.

[0030] In this embodiment, the first wall 120 includes two through bores 136. Each through bore 136 receives a respective one of the first rotor shaft 106 and the second rotor shaft 110. In other words, the first and second rotor shafts 106, 110 pass through the first wall 120 through their respective through bores 136. The first and second rotor shafts 106, 110 may be sealed against the first wall 120 (i.e., the walls of the through bores 136) by any suitable sealing means, such as a lip seal or a labyrinth seal.

[0031] In this embodiment, an outer surface 138 of the first wall 120 opposite the inner surface 130 of the first wall 120 includes a plurality of recesses. The outer surface 138 of the first wall 120 can be seen more clearly in Figure 5, which is a schematic illustration (not to scale) of a perspective view of the inverted first stator section 116.

[0032] More specifically, in this embodiment, the outer surface 138 of the first wall 120 includes a looped recess or groove 140. The looped groove 140 surrounds the through bore 136. The looped groove 140 may be positioned proximate the periphery of the outer surface 138.

[0033] In this embodiment, the outer surface 138 of the first wall 120 includes a plurality of recesses 142, which in this embodiment are substantially cylindrical. In this embodiment, the recesses 142 are disposed between the looped grooves 140 and the edges of the outer surface 138.

[0034] 1 and 2 , in this embodiment, a first O-ring 144 is disposed in the loop-shaped groove 140 on the outer surface 138 of the first wall 120. The first O-ring 144 may be made of any suitable material, such as polytetrafluoroethylene (PTFE). Preferably, the first O-ring 144 is made of a thermally insulating material. Also in this embodiment, a plurality of first spacers 146 are disposed in the plurality of recesses 142, respectively. The first spacers 146 may be substantially cylindrical. In this embodiment, the first spacers 146 are made of a thermally insulating material, such as a ceramic material.

[0035] The first head plate 112 is disposed facing or opposite the outer surface 138 of the first wall 120. The first head plate 112 is disposed in contact with a first O-ring 144 and a first spacer 146. The first O-ring 144 and / or the first spacer 146 maintain 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, i.e., between the outer surface 138 of the first wall 120 and the facing surface of the first head plate 112.

[0036] The first head plate 112 is configured to support the first and second rotor shafts 106, 110 at their lower ends. The first head plate may be a conventional head plate. The first head plate 112 may include bearings and / or a seal system for supporting the rotor shafts 106, 110.

[0037] In this embodiment, one or more of the first side walls 122 includes a first flange 150 at an end of the first side wall 122 opposite the first wall 120 .

[0038] The second stator portion 118 includes a second wall 152 and one or more second side walls 154 extending from the second wall 152. The second wall 152 may be considered a top wall or second end wall of the stator 102. The one or more second side walls 154 extend downwardly from the second wall 152. The second wall 152 and the one or more second side walls 154 define an interior cavity. The second wall 152 and the one or more second side walls 154 may be a single, unitary element.

[0039] The second stator portion 118 further includes an inlet passage 155. The inlet passage 155 is a gas inlet for the stator 102. The inlet passage 155 is formed through one or more of the second side walls 154.

[0040] In this embodiment, the second wall 152 includes two through bores 156. Each through bore 156 receives a respective one of the first rotor shaft 106 and the second rotor shaft 110. In other words, the first and second rotor shafts 106, 110 pass through the second wall 152 through their respective through bores 156. The first and second rotor shafts 106, 110 may be sealed against the second wall 152 (i.e., the walls of the through bores 156) by any suitable sealing means, such as a lip seal or a labyrinth seal.

[0041] In this embodiment, the outer surface 158 of the second wall 152 includes a plurality of recesses, which can be seen more clearly in Figures 6 and 7, which are schematic illustrations (not to scale) of perspective views of the second stator portion 118.

[0042] More specifically, in this embodiment, the outer surface 158 of the second wall 152 includes a looped recess or groove 160. The looped groove 160 surrounds the through bore 156. The looped groove 160 may be positioned proximate the periphery of the outer surface 158.

[0043] In this embodiment, the outer surface 158 of the second wall 152 includes a plurality of recesses 162, which in this embodiment are substantially cylindrical. In this embodiment, the recesses 162 are disposed between the looped groove 160 and the edge of the outer surface 158.

[0044] 1 and 2 , in this embodiment, a second O-ring 164 is disposed in the loop-shaped groove 160 on the outer surface 158 of the second wall 152. The second O-ring 164 may be made of any suitable material, such as polytetrafluoroethylene (PTFE). Preferably, the second O-ring 164 is made of a thermally insulating material. Also in this embodiment, a plurality of second spacers 166 are disposed in the plurality of recesses 162, respectively. The second spacers 166 may be substantially cylindrical. In this embodiment, the second spacers 166 are made of a thermally insulating material, such as a ceramic material.

[0045] The second head plate 114 is disposed facing or opposite the outer surface 158 of the second wall 152. The second head plate 114 is disposed in contact with a second O-ring 164 and a second spacer 166. The second O-ring 164 and / or the second spacer 166 maintain 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, i.e., between the outer surface 158 of the second wall 152 and the facing surface of the second head plate 114.

[0046] The second head plate 114 is configured to support the first and second rotor shafts 106, 110 at their upper ends. The second head plate 114 may be a conventional head plate. The second head plate 114 may include a bearing and / or seal system for supporting the rotor shafts 106, 110.

[0047] In this embodiment, one or more of the second side walls 154 includes a second flange 170 at an end of the second side wall 154 opposite the second wall 152 .

[0048] 1-4, in an assembled configuration, 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 and fastened together via the first and second flanges 150, 170 by a number of fasteners (not shown).

[0049] The walls of the first stator portion 116 and the second stator portion 118, i.e., the first wall 120, the first sidewall 122, the second wall 152, and the second sidewall 154, define an internal cavity or chamber 171. This chamber 171 may also be referred to as a stator bore. This chamber 171 is the pumping chamber of the vacuum pump 100. The rotors 104, 108 are disposed within the chamber 171.

[0050] In operation, one or more motors (not shown) drive rotor shafts 106, 110, thereby rotating rotors 104, 108 about parallel axes within chamber 171. This rotation of rotors 104, 108 draws gas into suction side 172 of chamber 171 through inlet 155, as indicated by arrow and reference numeral 174 in FIG. 1. Following continued rotation of rotors 104, 108, gas travels from suction side 172 of chamber 171 to exhaust side 176 of chamber 171, as indicated by arrow and reference numeral 178 in FIG. 1. Following continued rotation of rotors 104, 108, gas travels from exhaust side 176 of chamber 171 out of outlet 124, as indicated by arrow and reference numeral 180 in FIG. 1.

[0051] Thus, rotors 104, 108 can be viewed as dividing chamber 171 into a suction side 172 (where inlet 155 is located) and an exhaust side 176 (where outlet 124 is located).

[0052] The fluid (e.g., gas) pumped by the vacuum pump 100 may contain or be accompanied by liquid and / or particulate matter, such as dust. Additionally, the pumped fluid may condense on surfaces within the chamber 171. This liquid and / or particulate matter tends to fall to the bottom of the pumping chamber 171 due to gravity and may collect on the first wall inner surface 130. Advantageously, the inner surface 130 of the first wall 120, which is continuous with the first opening 126 of the outlet passage 124, tends to encourage the liquid and / or particulate matter to flow or migrate out of the pumping chamber through the outlet 124. This flow of liquid and / or removal of particulate matter from the chamber 171 tends to be further facilitated by the fact that the lowest point of the inner surface 130 is continuous with the first opening 126 and / or the inner surface 130 is sloping downwardly toward the first opening 126.

[0053] Advantageously, therefore, accumulation of potentially flammable, corrosive, or otherwise hazardous liquids and / or particulate matter within the pump chamber 171 tends to be reduced or eliminated. Furthermore, impedance of, for example, the rotors 104, 108 by liquids and / or particulate matter tends to be reduced or eliminated. Thus, the pumping efficiency of the pump tends to be improved.

[0054] Advantageously, the spatial separation of the stator 102 and the head plates 112, 114 by the O-rings 144, 164 and spacers 146, 166 (i.e., the presence of the 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. Thus, in embodiments where the temperature of the stator 102 is relatively high, the temperature of the head plates can nevertheless remain relatively low. For example, in some embodiments, the temperature of the stator 102 may be approximately 200° C., while the temperature of the head plates 112, 114 may be approximately 100° C. This advantageously tends to improve the operation of the vacuum pump 100.

[0055] In this embodiment, second stator portion 118 further includes a flow passage 182 formed in second wall 152. Flow passage 182 extends between a first opening 184 and a second opening 186.

[0056] In this embodiment, the first opening 184 is formed in an inner surface 188 of the second wall 152, the inner surface 188 being opposite the outer surface 158. The first opening 184 is located on the exhaust side 176 of the chamber 171.

[0057] In this embodiment, the 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.

[0058] In this embodiment, a pressure relief valve 190 is disposed in the flow path 182 between the first opening 184 and the second opening 186. In this embodiment, the pressure relief valve 190 is configured to prevent fluid flow through the flow path 182 when the pressure differential across the pressure relief valve 190 is below a predetermined threshold. Additionally, the pressure relief valve 190 is configured to allow fluid flow through the flow path 182 when the pressure differential across the pressure relief valve 190 is equal to or greater than a predetermined threshold.

[0059] Thus, in this embodiment, during operation, if the pressure differential across pressure relief valve 190, i.e., the pressure differential between exhaust side 176 of chamber 171 and suction side 172 of chamber 171, is equal to or greater than a preset threshold, pressure relief valve 190 opens to allow flow of pumped fluid from exhaust side 176 of chamber 171 to suction side 172 of chamber 171 through flow path 182. This advantageously tends to reduce the pressure differential between exhaust side 176 and suction side 172. In other words, the pressure differential across rotors 104, 108 is reduced. Thus, the risk of damage to rotors 104, 108 tends to be reduced.

[0060] Advantageously, having the flow path 182 fluidly connect the exhaust side 176 and the suction side 172 tends to allow for a rapid reduction in the pressure differential between the exhaust side 176 and the suction side 172. Nevertheless, in some embodiments, the flow path 182 can fluidly connect the pump chamber 171 (e.g., the exhaust side 176 of the chamber 171) and the environment external to the pump 100.

[0061] The pressure relief valve 190 is disposed or housed within the stator 102, and more specifically, in this embodiment, within the second wall 152 of the stator 102. The pressure relief valve 190 can be considered to be integral with or incorporated within the stator 102. During use, the temperature of the stator 102 tends to be relatively high compared to the temperature of, for example, the head plates 112, 114. For example, in some implementations, the temperature of the stator 102 may be approximately 200°C, while the temperature of the head plates 112, 114 may be approximately 100°C. The relatively high temperature of the stator 102 tends to reduce or eliminate condensation of the pumped fluid within the flow passages 182. This advantageously tends to reduce or eliminate condensation that could interfere with operation of the pressure relief valve 190.

[0062] In this embodiment, the pressure relief valve 190 is disposed in a housing that is removable from the stator through a side opening in the second end wall 152. This advantageously tends to facilitate inspection, maintenance, service, and / or repair of the pressure relief valve 190.

[0063] Advantageously, by locating the pressure relief valve 190 at the top of the stator, i.e., at the top end wall, any particulate matter or fluid that enters the flow passage 182 tends to fall out of the flow passage 182 (i.e., the duct of the pressure relief valve) rather than accumulate.

[0064] In some embodiments, the flow path 182 is multi-branched (e.g., a branched flow path) having multiple first openings (or inlets) and / or multiple second openings (or outlets). In some embodiments, multiple pressure relief valves can be disposed within the flow path.

[0065] In the above embodiment, the vacuum pump is a vertically oriented Roots-type vacuum pump. However, in other embodiments, the vacuum pump is a different type of vacuum pump. The vacuum pump may have, for example, any number of stages, pump chambers, rotors, and rotor shafts.

[0066] In the above embodiment, the stator is formed from two parts that are attached together to form the stator, however, in other embodiments the stator is formed from only a single part or a different number of parts, such as three or more parts that are attached together to form the stator.

[0067] In the above embodiment, the inlet is formed in the second stator portion. However, in other embodiments, the inlet is located in a different stator portion, such as the first stator portion. In some embodiments, the inlet is formed through multiple different stator portions.

[0068] In the above embodiment, 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 or be integral with the stator.

[0069] In the above embodiments, the second stator portion includes a flow passage in which the pressure relief valve is disposed. However, in other embodiments, the flow passage and the pressure relief valve disposed therein may be disposed in a different portion of the stator, such as the first stator portion, e.g., the first wall. In some embodiments, the flow passage and the pressure relief valve therein may be omitted.

[0070] 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 the second stator portion. In some embodiments, the outlet is formed through multiple different stator portions. [Explanation of symbols]

[0071] 100 Vacuum Pump 102 Stator 104 First Rotor 106 first rotor shaft 108 Second Rotor 110 second rotor shaft 112 First head plate 114 Second Head Plate 116 first stator portion 118 second stator part 120 The First Wall 122 First side wall 124 Outlet channel 126 First Opening 128 Second Opening 130 Inside 132 bottom surface 134 Horizontal plane 136 Through Bore 138 Exterior 140 Loop groove 142 recess 144 First O-ring 146 First spacer 148 Gap 150 First flange 152 The Second Wall 154 Second Side Wall 155 Entrance Route 156 through bore 158 Exterior 160 Loop groove 162 recess 164 Second O-ring 166 Second Spacer 168 Gap 170 Second flange 171 Chamber 172 Suction side 174 Suction gas flow direction 176 Exhaust side 178 Gas flow direction 180 Exhaust gas flow direction 182 channels 184 First Opening 186 Second Opening 188 Inside 190 Pressure relief valve

Claims

1. 1. A vertically oriented vacuum pump, comprising: A stator including a first stator portion and a second stator portion disposed on the first stator portion, the first stator portion a first wall forming a bottom wall of the stator; one or more side walls extending upwardly from the first wall, the first wall and the one or more side walls being a single, unitary element and defining an interior cavity; an outlet passage formed through a sidewall of the one or more sidewalls, the outlet passage having an opening on an interior surface of the sidewall of the one or more sidewalls, the outlet passage allowing fluid to flow from the internal cavity to an exterior of at least a portion of the stator; Equipped with the second stator portion a second wall forming a top wall of the stator; one or more additional side walls extending downwardly from the second wall, wherein the second wall and the one or more additional side walls are a single unitary element; and Equipped with an inner surface of the first wall is continuous with the opening of the outlet channel; the outlet channel extends from the opening of the outlet channel in a direction having a downward component; the one or more side walls of the first stator portion are attached to the one or more further side walls of the second stator portion such that the first wall, the one or more side walls, the second wall, and the one or more further side walls define an interior chamber; the stator further comprises an inlet passage formed through a sidewall of the one or more additional sidewalls, the inlet passage for allowing fluid to enter the internal chamber from outside the stator; the stator further comprising a pressure relief valve disposed in the second wall. Vertically oriented vacuum pump.

2. 2. The vertically oriented vacuum pump of claim 1, wherein the lowest point of the inner surface of the first wall is continuous with the opening of the outlet passage.

3. 2. The vertically oriented vacuum pump of claim 1, wherein the inner surface of the first wall is either sloped or flat toward the opening.

4. 2. A vertically oriented vacuum pump as claimed in claim 1, wherein the first wall has one or more through bores, each of the one or more through bores for receiving a respective rotor shaft.

5. 2. The vertically oriented vacuum pump of claim 1, wherein the first wall comprises an outer surface opposite the inner surface, the outer surface of the first wall comprising one or more recesses.

6. 6. A vertically oriented vacuum pump according to claim 5, wherein the one or more recesses in the outer surface of the first wall comprise one or more recesses selected from the group of recesses consisting of looped grooves for receiving O-rings and recesses configured to receive insulating spacers.

7. 2. A vertically oriented vacuum pump as claimed in claim 1, wherein the second wall includes one or more through bores, each of the one or more through bores for receiving a respective rotor shaft.

8. 10. The vertically oriented vacuum pump of claim 1, wherein the second wall comprises an outer surface, the outer surface of the second wall comprising one or more recesses.

9. 9. A vertically oriented vacuum pump according to claim 8, wherein the one or more recesses in the outer surface of the second wall comprise one or more recesses selected from the group of recesses consisting of looped grooves for receiving O-rings and recesses configured to receive insulating spacers.

10. the stator further comprises a flow passage formed in the second wall; the flow path includes a first opening located at a first end of the flow path and a second opening located at a second end of the flow path; the first opening and the second opening of the flow path are formed on an inner surface of the second wall; 2. The vertically oriented vacuum pump of claim 1, wherein the pressure relief valve is disposed in the flow path.

11. one or more rotor shafts extending through the interior chamber of the stator between the first wall and the second wall; one or more rotors; A vacuum pump comprising:

2. A vertically oriented vacuum pump as claimed in claim 1, wherein each of said rotors is mounted on a respective one of said rotor shafts.

12. the one or more rotors define an intake side of the internal chamber and an exhaust side of the internal chamber; the stator further comprises a flow passage formed in the second wall; the flow path includes a first opening located at a first end of the flow path and a second opening located at a second end of the flow path; the first opening of the flow passage is formed in an inner surface of the second wall on the exhaust side of the internal chamber; the second opening of the flow passage is formed in the inner surface of the second wall on the suction side of the internal chamber; 12. The vertically oriented vacuum pump of claim 11, wherein the vacuum pump further comprises a pressure relief valve disposed in the flow path.

13. the first wall has an outer surface, the outer surface of the first wall having one or more recesses formed therein; The vacuum pump a first O-ring and / or a first insulating spacer disposed in the one or more recesses formed in the outer surface of the first wall; a first head plate for supporting the one or more rotor shafts; Furthermore, 12. The vertically oriented vacuum pump of claim 11, wherein the first head plate is positioned opposite the outer surface of the first wall and in contact with the first O-ring and / or the first insulating spacer, and the first head plate is spaced from the outer surface of the first wall.

14. the second wall has an outer surface, the outer surface of the second wall having one or more recesses formed therein; The vacuum pump a second O-ring and / or a second insulating spacer disposed in the one or more recesses formed in the outer surface of the second wall; a second head plate for supporting the one or more rotor shafts; Furthermore, 12. The vertically oriented vacuum pump of claim 11, wherein the second head plate is positioned opposite the outer surface of the second wall and in contact with the second O-ring and / or the second insulating spacer, and the second head plate is spaced from the outer surface of the second wall.

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