KR20240000380U - Stator assembly for Roots vacuum pumps - Google Patents

Abstract

This disclosure provides a stator assembly for a Roots vacuum pump. The stator assembly includes an interstage stator portion to separate the first rotor stage and the second rotor stage. The interstage stator portion includes a plurality of gas flow passages defined therein, the plurality of gas flow passages being configured to provide fluid communication between the first rotor stage and the second rotor stage through the interstage stator portion. The present disclosure also provides a Roots vacuum pump including a stator assembly and a method of directing gas through the interstage stator portion.

Description

Stator assembly for Roots vacuum pumps

This disclosure relates to a stator assembly for a Roots vacuum pump. The present disclosure also relates to a Roots vacuum pump comprising this assembly and a method of delivering gas flow through a stator of the Roots vacuum pump.

Vacuum systems typically utilize pumps to evacuate gases from the system. One type of vacuum pump used in such systems is the Roots vacuum pump.

Roots vacuum pumps typically include two counter-rotating shafts, each equipped with a rotor. The rotor includes a series of lobes and defined recesses between the lobes. The rotor is mounted so that the lobes of the rotor on one shaft cooperate with corresponding recesses of the rotor on the other shaft. As the shaft and rotor rotate, gases are trapped and compressed between the cooperating lobes and recesses. The repeated capture and compression of gas between the rotors creates a pumping action that can be used to pump gas from an inlet on one side of the rotor to an outlet on the other side to evacuate the system.

Roots vacuum pumps typically feature multiple stages of cooperating rotors; Each stage is axially spaced along the shaft and separated by a stator structure. By having multiple stages, a gradual increase in gas compression can occur across the pump, providing a higher degree of vacuum to the system in an efficient manner.

It is necessary to transfer gas between the inlet, rotor stage and outlet. This is typically accomplished by providing a defined gas flow path between these components through a stator structure separating the rotor stages.

Accommodating the gas flow path in the stator structure can negatively increase the length and size of the Roots vacuum pump. Therefore, there is a need to improve the design of the stator structure and the gas flow path therein to enable a more compact pump design without affecting pump efficiency.

In one aspect, the present disclosure provides a stator assembly for a Roots vacuum pump according to claim 1.

The plurality of gas flow passages allow gas compressed by a first rotor stage to be passed to the next successive rotor stage for further compression. In other words, the interstage stator portion allows for gas transfer from the outlet of the first rotor stage to the inlet of the second rotor stage.

The first and second rotor stages are axially spaced generally along the longitudinal axis, with an interstage stator portion axially sandwiched between them (i.e., separating them axially).

Providing a plurality of gas flow passages through the interstage stator portion (e.g., compared to known interstage stator portion configurations with a single gas flow passage) may affect the size (e.g., thickness or axial flow) of the interstage stator portion. Allows for an increase in flow area through the stator section between stages without the need to increase the length. This can maintain a more compact size while keeping resistance to gas flow through the stator assembly to a minimum.

In one embodiment of the above, the interstage stator portion includes a first hole for receiving the first rotor shaft and a second hole for receiving the second rotor shaft.

The first and second holes allow the rotor shaft to pass through the interstage stator portion. This means that the rotor shaft can rotate to actuate the rotor stages without being impeded by the interstage stator portion.

The first and second holes are spaced generally transversely to the longitudinal axis. In some embodiments, the hole may be sized to provide sufficient clearance around the shaft to allow the shaft to rotate freely within the hole, and in other embodiments, a bearing may be installed inside the hole to help support the shaft for rotation within the hole. can be included in

In a further embodiment of any of the above, the plurality of gas flow passages includes a first gas flow passage, a second gas flow passage, and a third gas flow passage. A first gas flow passage extends through a central region of the interstage stator portion between the first and second apertures. A second gas flow passage extends through a first side area of the interstage stator portion around the first aperture. A third gas flow passage extends through a second side area of the interstage stator portion around the second aperture.

The side areas are areas on either side of the central area transverse to the longitudinal axis. In other words, a left area to the left of the central area transverse to the longitudinal axis (i.e., around the first hole) and a right area to the right of the central area transverse to the longitudinal axis (i.e., around the second hole). there is.

This configuration of the gas flow passages provides a balanced flow area around different areas of the stator portion between stages. Additionally, better use of all available space within the interstage stator portion maximizes the gas flow area through the interstage stator portion. Accordingly, this configuration may allow a much more compact interstage stator section to be realized while maintaining pump efficiency.

In a further embodiment of any of the above, the second and third gas flow passages branch from the first gas flow passage and are fluidly connected to the first gas flow passage at both a beginning and an end.

In other words, the second and third gas flow passages extend outwardly from the first gas flow passage and extend through each side region (i.e., around each orifice) before rejoining the first gas flow passage. .

This configuration provides a compact arrangement of gas flow passages that convey gas flow around different areas of the stator portion between stages.

In a further embodiment of any of the above, the second and third gas flow passages each define a generally C-shaped gas flow path around a respective one of the first and second apertures.

The C-shape of the second and third gas flow passages allows the second and third gas flow passages to bend around the first and second holes, respectively. This also helps maximize the space available for gas flow through the stator section between stages.

In further embodiments of any of the above, the stator assembly is formed of two stator halves connected to each other.

In this way, the stator assembly can be manufactured more simply by casting the two halves separately and then assembling them together. The halves may be fastened together using removable means (eg, threaded fasteners). Additionally, the halves make the inspection, maintenance and replacement process of the stator assembly and rotor components housed therein during pump operation simpler.

In a further embodiment of the above, the interstage stator portion is formed by two opposing generally W-shaped portions that are joined together when the two stator halves are connected to each other.

In other words, each stator half defines a corresponding half of an interstage stator portion, and this half of the interstage stator portion is generally W-shaped transverse to the longitudinal axis.

By being generally W-shaped, the halves of the interstage stator portion are intended to form generally two joined U-shaped shapes across the transverse direction. When the halves of the W-shaped inter-stage stator portion are joined together, they generally form a ∞ shape (or two joined O-shapes across the transverse direction). The coupled area corresponds to the central area of the inter-stage stator, and each side of the uncoupled O-shape corresponds to the side area of the inter-stage stator. The U/O shape is generally defined by recesses in the W-shaped portion that, when joined together, form first and second apertures. The recess may be generally semi-circular in shape and the resulting hole may be generally circular in shape.

In another embodiment of the above, the plurality of gas flow passages are defined through two generally W-shaped portions and are defined by a plurality of cavities each of which is fluidly connected when the two generally W-shaped portions are joined together.

A stator assembly having a W-shaped portion that forms one half of an interstage stator portion and using internal cavities to form a gas flow passage when joined together (i.e., compared to an interstage stator portion that is not divided into two halves). Simpler casting molds can be used for manufacturing.

In a further embodiment of any of the above, the interstage stator portion includes an inlet opening for receiving fluid from the first rotor stage and an outlet opening for conveying fluid from the interstage stator portion to the second rotor stage. A plurality of gas flow passages are disposed between the inlet opening and the outlet opening and fluidly connect the inlet opening to the outlet opening.

In this way, a plurality of gas flow passages are supplied with a gas flow by a common inlet and deliver the gas flow to a common outlet. This can also help simplify the casting mold for manufacturing the stator assembly and helps maintain balanced gas flow distribution through the stator section between stages.

In a further embodiment of any of the above, the stator assembly includes a plurality of interstage stator portions.

This may further allow the stator assembly to separate additional rotor stages. For example, a second interstage stator portion may be used to separate the second rotor from the third rotor and transfer gases between the two. Indeed, within the scope of the present disclosure, a stator assembly may have any number of interstage stator portions depending on the number of adjacent rotor stages that need to be separated while allowing fluid communication.

In another aspect, the present disclosure provides a (multi-stage) Roots vacuum pump comprising the stator assembly of the above aspect or any of the embodiments thereof.

The pump further includes a first (upstream) rotor stage and a second (downstream) rotor stage spaced apart along the longitudinal axis of the pump. The interstage stator portion of the stage assembly separates the first rotor stage from the second rotor stage along the longitudinal axis, and the plurality of gas flow passages receive fluid from the first (upstream) rotor stage and direct fluid to the second (downstream) rotor. It is configured to be delivered to the stage.

In any of the above embodiments, the pump further includes a pair of rotor shafts extending along a longitudinal axis, each rotor stage having first and second lobe stages mounted to rotate with a respective one of the rotor shafts. Includes rotor.

Each of the rotor shafts is arranged to pass through the first and second holes. The hole may be sized to allow the shaft to pass through the hole and rotate freely within the hole. In another example, the hole may contain a bearing therein that supports a shaft to rotate.

The pump may also include a motor operatively coupled to the shaft and configured to rotationally drive the shaft.

By using the stator assembly of a Roots vacuum pump, the overall length and size of the pump for a given capacity can be reduced. This allows Roots vacuum pumps to be expanded into new applications that require more compact pumps.

In another aspect, the present disclosure provides a method of transferring gas from a first (upstream) rotor stage of a (multi-stage) Roots vacuum pump to a subsequent second (downstream) rotor stage. The method includes providing a stator assembly having an interstage stator portion separating first and second rotor stages, and a plurality of gas flow passages configured to receive fluid from the first rotor stage and transfer fluid to the second rotor stage. It includes placing through the stator portion between stages.

Providing a plurality of gas flow passages through the interstage stator portion (e.g., compared to known interstage stator portion configurations with a single gas flow passage) may affect the size (e.g., thickness or axial flow) of the interstage stator portion. Allows for an increase in flow area through the stator section between stages without the need to increase the length.

In one of the above embodiments, the plurality of gas flow passages include a first gas flow passage, a second gas flow passage, and a third gas flow passage. The method includes defining a first gas flow passage through a central region of the interstage stator portion between two holes for receiving each rotor shaft, and defining a first gas flow passage through the interstage stator portion about the first of the two holes. and defining a second gas flow passage through a first side region of the and defining a third gas flow passage through a second side region of the interstage stator portion about the second of the two apertures.

This configuration of the gas flow passages provides a balanced flow area around different areas of the stator portion between stages. Additionally, better use of all available space within the interstage stator portion maximizes the gas flow area through the interstage stator portion.

In any of the above embodiments, the plurality of gas flow passages are defined by forming a plurality of cavities in each of two opposing stator halves. The method further includes coupling the stator halves to each other such that each plurality of cavities is fluidly connected to each other to form a respective gas flow passage of the plurality of gas flow passages.

This not only allows simpler manufacturing of the interstage stator portions and associated gas flow passages therein, but also makes their inspection, maintenance and replacement processes simpler.

The above methods and embodiments thereof may utilize the stator assembly and/or Roots vacuum pump discussed in the above aspects and any accompanying embodiments.

Although certain advantages have been discussed in connection with certain features above, other advantages of certain features may become apparent to those skilled in the art following this disclosure.

Now, one or more non-limiting embodiments according to the present disclosure will now be described with reference to the accompanying drawings:
1 shows a perspective plan view of an example of a prior art Roots vacuum pump;
Figure 2 shows a perspective cross-sectional view of the pump of Figure 1 along line AA;
Figure 3 shows an axial cross-section of the pump of Figure 2 along line BB;
Figure 4A shows a perspective view of the upper half of the stator assembly of the pump of Figure 1;
Figure 4B shows a perspective view of the lower half of the stator assembly of the pump of Figure 1;
Figure 5A shows a perspective view of the upper half of a stator assembly for a Roots vacuum pump according to one embodiment of the present disclosure;
FIG. 5B shows a perspective view of the lower half of a stator assembly for a Roots vacuum pump according to one embodiment of the present disclosure;
6 shows an axial cross-sectional view of a stator assembly for a Roots vacuum pump according to one embodiment of the present disclosure.

To provide a better understanding of embodiments of the present disclosure, a known multi-stage Roots vacuum pump and its stator assembly are shown in Figures 1-4B and discussed below for comparison.

1 shows the Roots vacuum pump 100 defined along the longitudinal axis L. As is generally known, the pump 100 includes a motor 102 attached to one axial end 104a of the outer casing 104, and an end attached to the other axial end 104b of the outer casing 104. Includes cap 106.

Motor 102 is operatively connected to two rotor shafts equipped with multiple rotor stages. As discussed in the background above, the shaft operates to rotate the rotor stage for pump operation.

The outer casing 104 includes a gas inlet 108 defined at the axial end 104b, which is used to deliver gas to the pump 100 from the system or environment to be evacuated. The outer casing 104 also has a gas outlet 109 at the other axial end 104a (on the lower side of the pump 100), which allows the exhausted gas to be discharged, for example, into the surroundings or the atmosphere. so that it can be discharged.

Gas inlet 108 and gas outlet 109 are holes through outer casing 104 and can have any suitable shape. They may also include mounting bosses and hardware around them for securing appropriate inlet and exhaust systems (eg, inlet and exhaust piping).

Figure 2 shows a cross-sectional view of pump 100 along line A-A. Pump 100 includes seven rotor stages 110a - 110g axially spaced along longitudinal axis L (however, any number of stages may be used depending on the application). Although seven rotor stages (110a-110g) are shown, the present disclosure is likewise suitable for use with a multi-stage Roots vacuum pump (100) having any number of stages, i.e., multiple stages/two or more stages. It must be understood.

Although not shown, as is generally known and discussed above, rotor stages 110a-110g include cooperating pairs of lobed rotors mounted on respective counter-rotating shafts. The shaft may be supported at both axial ends 104a and 104b by bearing assemblies 103a and 103b received in the motor 102 and end cap 106, respectively.

The outer cover 104 includes a stator assembly 120 that includes inter-stage stator portions 122a through 122f sandwiched between each rotor stage 110a through 110g. In this way, stator portions 122a to 122f are used to separate successive rotor stages 110a to 110g. The number of interstage stator portions 122a through 122f will vary depending on the number of rotor stages 110a through 110g utilized in a particular design.

Each of the stator portions 122a to 122f defines therein a gas flow passage 124 that allows fluid communication between axially adjacent (i.e., consecutive) rotor stages 110a to 110g. In this way, stator portions 122a to 122f fluidly connect successive rotor stages 110a to 110g in series. Gas flow passages 124 extend generally radially upward with respect to the longitudinal axis and thus collect compressed gas from the outlet of one rotor stage (at the “bottom” of stator assembly 120 ) and thereby collect compressed gas from the outlet of one rotor stage (at the “bottom” of stator assembly 120 ). (from the "top") to the beginning of the next successive rotor stage.

This creates a gas flow path G through the pump 100 from the gas inlet 108, successively passing through each rotor stage 110a to 110g before exiting the gas outlet 109. This gas flow path G ensures that work on the gas is carried out in a continuous manner by each of the rotor stages 110a to 110g, allowing the pump to produce higher levels of compression in any efficient manner. .

Figure 3 is an axial cross-sectional view through stator portion 122a showing aspects of the construction of stator assembly 120 more clearly. Other stator portions 122b to 122f also share the same configuration and characteristics. Accordingly, the following description also applies to these stator parts.

The stator assembly 120 is formed of two halves, a stator upper half 120a and a stator lower half 120b. The stator upper and lower halves 120a and 120b are held together by fasteners 130a and 130b and contact each other along the boundary surface 123.

Fasteners 130a, 130b pass through holes in attachment flanges 132a, 132b defined on each stator half 120a, 120b and are threadedly received within the holes. These removable attachment means facilitate removal and replacement of stator halves 120a and 120b for pump assembly, inspection and maintenance activities. Nonetheless, any other suitable attachment means may be used. For example, stator halves 120a and 120b are welded together along interface 123.

The stator upper and lower halves 120a, 120b define internally gas flow cavities 125a, 125b that define a gas flow passage 124 when the stator halves 120a, 120b are coupled together. Cavities 125a and 125b are hollow regions of stator halves 120a and 120b.

The stator upper and lower halves 120a, 120b are also complementary shaped to form two shaft holes 121. The shaft hole 121 is formed by defining two generally semicircular shaft recesses 121a and 121b in the stator upper and lower halves 120a and 120b. When the stator halves 120a, 120b are joined together, the recesses 121a, 121b thereby form two circular shaft holes 121.

Holes 121 are positioned and sized to allow two counter-rotating rotor shafts (not shown) to pass through stator assembly 120 and rotate rotor stages 110a-110g for pump operation.

Stator assembly 120 and halves 120a, 120b may be made of any suitable material. For example, it may be made of metal materials such as cast iron or graphite iron. Other suitable metallic materials include, but are not limited to, steel alloys and aluminum alloys. As will be appreciated, specific materials may be selected depending on the particular application and operating conditions.

Stator assembly 120 and halves 120a, 120b may be formed in any suitable manner. For example, they can be cast. In another example, additive manufacturing may be used.

Although the specific configuration of stator assembly 120 has been discussed above, it should be understood that stator assembly 120 may be configured in any other suitable manner.

For example, instead of stator halves 120a and 120b, stator assembly 120 may instead be formed as a single piece.

The specific shapes of the gas flow passages 124 and holes 121 (and the recesses 121a, 121b and cavities 125a, 125b that form them) can also be easily modified and changed depending on the needs of a particular application.

4A and 4B show perspective views of stator halves 120a and 120b, respectively.

For each successive stator portion 122a through 122f, the stator upper half 120a includes a respective gas flow cavity 125a defining an opening 126a at the interface 123, and the stator lower half 120b includes a respective gas flow cavity 125a defining an opening 126a at the interface 123. 123 includes each gas flow cavity 125b providing an opening 126b. As will be understood, when the stator halves 120a, 120b are joined together, the openings 126a, 126b of each stator portion 122a - 122f are joined at the interface 123, and thus the cavities 125a, 125b) are fluidically connected to form each gas flow passage 124.

As shown, each stator portion 122a to 122f is formed by the combination of two generally W-shaped portions 140a and 140b of the stator upper and lower halves 120a and 120b.

By being generally W-shaped, it should be understood that the shape is generally the shape of two joined U-shapes. This shape is due in part to the shaft recesses 121a, 121b and gas inlet and gas outlet openings 128, 129 defined in the upper and lower halves of stator portions 122a through 122f (discussed further below). ).

However, stator halves 120a, 120b need not be limited to just this shape, and may be any other suitable shape to accommodate any particular configuration of flow passages, inlets, and outlets through stator portions 122a through 122f. It may be possible.

As shown in Figure 3, the cavities 125a, 125b and the gas flow passages 124 formed thereby radially extend the W-shaped portions 140a, 140b in a central region defined between the shaft recesses 121a, 121b. passes through. Accordingly, the openings 126a and 126b are opened at the boundary surfaces of the central regions of the W-shaped portions 140a and 140b.

In contrast, the curved U-shaped regions on either side of this central region (i.e., around the outside of each shaft recess 121a, 121b) are the side regions of the W-shaped portions 140a, 140b (i.e., the W-shaped portion ( 140a, 140b) left and right areas). These lateral regions are solid and, unlike the central region, do not contain any cavities or openings.

Each cavity 125b has an inlet opening 128 that guides gas from the outlet of each rotor stage 110a to 110f into the respective gas flow passage 124. Each cavity 125a has an outlet opening 129 exiting the respective gas flow passage 124 to allow gas to pass to the next successive rotor stage 110b to 110g.

In the example shown, the stator lower half 120b scoops under each inlet opening 128 to help divert the gas flow exiting the rotor stages 110a through 110f into the gas flow passage 124. The contour is formed to give (127). A corresponding scoop (not visible) of the stator upper half 120a above each outlet opening 129 also directs the gas flow exiting the gas flow passage 124 to the inlet of the next successive rotor stage 110b through 110g. It can exist to help you make the transition.

Both the upper and lower stator halves 120a and 120b include an end plate 131 at the axial end 104a that serves to close the final rotor stage 110g. This causes the gas flow exiting the final rotor stage 110g to be confined through the stator lower half 120b at the axial end 104a (i.e., axially between the final stator portion 122f and the end plate 131). Guide it to the gas outlet 109 of the pump 100.

Both stator upper and lower halves 120a and 120b include mounting flanges 133a and 133b at axial ends 104a and 104b, respectively. A mounting flange 133a at the axial end 104a is for mounting the stator assembly 120 to the motor 102. The mounting flange 133b at the other axial end 104b is for mounting the stator assembly 120 to the end cap 106.

Gas inlet 108 passes axially through stator upper half 120a between mounting flange 133b and first stator portion 122a.

Openings 126a, 126b are shown as substantially rectangular with an axial length and width. However, the openings 126a, 126b may have any suitable regular or irregular shape (eg, circular or oval shape) depending on the radial cross-section of the cavities 125a, 125b that form them.

Gas flow passage 124 needs to have sufficient flow area to ensure that flow resistance is minimal as gas progresses through rotor stages 110a to 110g and stator portions 122a to 122f during pump operation. . If the flow area through certain stator portions 122a to 122f is insufficient for the amount of gas being pumped through them, a pressure drop may build up, which will negatively affect pump efficiency.

As such, the cavities 125a, 125b and openings 126a, 126b have sufficient volume and volume to support pumping of gas therethrough with minimal flow resistance (i.e., at least up to the maximum intended pumping capacity of pump 100). It is designed to have a flow area. The primary way to achieve this is to use cavities 125a, 125b and openings 126a to provide the gas flow passage 124 with sufficient volume and flow area to accommodate the maximum operating gas flow from each rotor stage 110a to 110f. 126b) is to set the dimensions.

As the gas passes from the high vacuum side of the pump 100 at the gas inlet 108 to the low vacuum side of the pump 100 at the gas outlet 109 and is continuously compressed by the rotor stages 110a to 110f, it The volume is reduced. As shown, the size and volume of the gas flow passage 124 will also become progressively smaller to compensate.

Dimensioning of the gas flow passage 124 to have sufficient gas flow capacity after each rotor stage 110a to 110f depends on the size of the stator portions 122a to 122f and their corresponding W-shaped portions 140a and 140b. affects. In particular, these parts should have sufficient axial length

Accordingly, the overall length and size of pump 100 will be limited by the required axial length (X) of each stator portion 122a to 122f.

5A, 5B, and 6 illustrate embodiments of the present disclosure designed to overcome these limitations in pump design. In particular, the embodiments of FIGS. 5A, 5B and 6 reduce the axial length Includes an auxiliary gas flow passage.

The main configuration and assembly of the pump and stator assembly (and other suitable examples thereof) discussed above with reference to FIGS. 1 to 4B are equally applicable to the embodiments of FIGS. 5A, 5B and 6, and thus as follows: will not be repeated.

Accordingly, unless specifically stated, the features of FIGS. 1-4B should be assumed to also apply to the embodiments of FIGS. 5A, 5B, and 6. In fact, the same reference numerals for features discussed above with respect to FIGS. 1-4B will remain the same in FIGS. 5A, 5B and 6 where these same features apply and need to be referenced for explanation. will be. Different features will be assigned new numbers in the form 2xx rather than 1xx.

5A and 5B show perspective views of the upper and lower stator halves 220a and 220b, respectively.

As shown, stator halves 220a and 220b correspond to stator halves 120a and 120b discussed above and share the features described above. However, stator halves 220a, 220b have additional cavities 225a, 225b, 235a, 235b (and corresponding It includes openings 226a, 226b, 236a, 236b).

Figure 6 shows an axial cross-section through stator portion 222a when halves 220a, 220b are joined together. Although stator portion 222a is shown, the same features may be applied to any of the other stator portions 222b through 222f.

5A and 5B explicitly show only the cavities 225a, 225b, 235a, 235b and openings 226a, 226b, 236a, 236b passing through the first three stator portions 222a, 222b, 222c. This means that, in the particular design shown, the gas is compressed to a sufficiently small volume after the fourth rotor stage 110d that additional gas flow passages 224, 234 are required for additional stator portions (224, 234) to maintain gas flow without significant flow resistance. This is because it is no longer needed in 222d, 222e, 222). However, it should be understood that additional gas flow passages 224, 234 may be used in any number of stator portions 222, depending on the gas flow and compression characteristics of the particular design.

As shown in FIG. 6 , cavities 125a and 125b extending through the central regions of W-shaped portions 140a and 140b define the centers of stator portions 122a through 122f (i.e., between shaft holes 121). A first gas flow passage 124 is provided therethrough. Cavities 225a, 225b and 235a, 235b (having corresponding openings 226a, 226b and 236a, 236b) extend through the aforementioned side regions of W-shaped portions 140a, 140b, forming stator portions 122a through 122f. ) (i.e., around the outside of the shaft hole 121) and provide additional second and third gas flow passages 224, 234.

In this way, the side region cavities 225a, 225b and 235a, 235b provide two opposing generally C-shaped gas flow passages 224 and 234 passing circumferentially around the exterior of each shaft hole 121. You can see that

Accordingly, the central gas flow path 124 provides a first gas flow path G 1 through the middle of the stator portion 222a, and the second and third gas flow paths 224, 234 provide a first gas flow path G ₁ through the middle of the stator portion 222a. ) It can be seen that the second and third gas flow paths (G ₂ , G ₃ ) are provided through the sides.

The additional side region gas flow passages 224, 234 act in conjunction with the central region gas flow passageway 124 to increase the flow area available for gas passing through stator portions 122a through 122f. This additional flow area means that the axial length (X) of the stator portions 122a to 122f can be reduced while maintaining minimal resistance to gas flow.

This may reduce the overall size of pump 100, which may advantageously lead to a more compact design. This can also expand the Roots vacuum pump design to new applications where a more compact pump is desirable.

As shown in FIG. 6 , the side region gas flow passages 224 and 234 are in fluid communication with the inlet opening 128 at one end through the central region gas flow passage 124. It is in fluid communication with the outlet opening 129 at the other end. In this way, the side region gas flow passages 224, 234 start at the central region gas flow passage 124 downstream of the inlet 128, curve around the hole 121, and then extend to the central region upstream of the outlet 129. They recombine/terminate in the regional gas flow passage 124. In other words, the side region gas flow passages 224 and 234 branch from the central region gas flow passageway 124 and are fluidly connected to the central region gas flow passageway at both starting and ending points.

However, it should be understood that within the scope of the present disclosure, many different configurations of additional gas flow passages 224, 234 may be provided.

For example, the side gas flow passages 224, 234 may not be C-shaped or may not be connected to/branch from the central gas flow passage 124. Instead, each side gas flow passage 224, 234 may have a dedicated gas inlet and outlet, and/or a substantially straight passage passing around the side of the stator portion 122/shaft hole 121 ( or another shape).

In the same vein, the side gas flow passages 224, 234 (and the corresponding cavities 225a, 225b and 235a, 235b and openings 226a, 226b and 236a, 236b) may be optional depending on the design requirements of the particular application. It may be formed to have a suitable cross-sectional shape (e.g., rectangular, square, circular, oval, etc.).

Additionally, although the depicted configuration provides three gas flow passages 124, 224, 234, the reduction in the axial length (X) of the stator portion 222 instead provides two gas flow passages (e.g. It should be understood that it can still be realized by using only two passages (124, 224, 234) or by using more than three gas flow passages. Number and configuration will vary depending on the gas flow area and pump size requirements for the particular application.

Nonetheless, note that by using gas flow passages 224, 234 passing around opposite sides of the stator portion, the gas flow is balanced around the sides (left and right) of the stator portion 222. Should be. This can advantageously provide a balanced directional flow of gas exiting the stator portion 222 for reception by the next rotor stage.

A list of reference numbers used in the attached Figures 1 to 4 is provided for convenience of reference:
100: Roots vacuum pump
102: motor
103a, 103b: bearing assembly
104: external casing
104a, 104b: axial end
106: end cap
108: gas inlet
109: gas outlet
110a to 110g: rotor stage
120: Stator assembly
120a, 120b: stator half
121: shaft hole
121a, 121b: shaft recess
122a to 122f: Stator portion between stages
123: boundary
124: Central gas flow passage
125a, 125b: central gas flow cavity
126a, 126b: central gas flow opening
127: Entrance Scoop
128: gas inlet opening
129: gas outlet opening
130a, 130b: Fastener
131: end plate
132a, 132b: Attachment flange
133a, 133b: Mounting flange
140a, 140b: W-shaped part
220a, 220b: stator half
222a to 222f: Stator portion between stages
224: Side gas flow path
225a, 225b: side gas flow cavity
226a, 226b: side gas flow opening
234: Side gas flow passage
235a, 235b: side gas flow cavity
236a, 236b: side gas flow opening
G: Gas flow path
G ₁ : first gas flow path
G ₂ : Second gas flow path
G ₃ : Third gas flow path
X: Stator part axial length
L: central longitudinal axis
AA: section line
BB: section line

Claims (15)

In the stator assembly for a Roots vacuum pump,
It includes an inter-stage stator portion for separating a first rotor stage and a second rotor stage, wherein the inter-stage stator portion includes a plurality of gas flow passages defined therein, and the plurality of gas flow passages are connected to the inter-stage stator. configured to provide fluid communication between the first rotor stage and the second rotor stage through a portion
Stator assembly. According to claim 1,
The interstage stator portion includes a first hole for receiving the first rotor shaft and a second hole for receiving the second rotor shaft.
Stator assembly. According to claim 2,
The plurality of gas flow passages include a first gas flow passage, a second gas flow passage, and a third gas flow passage, wherein the first gas flow passage is an inter-stage stator portion between the first hole and the second hole. extending through a central region of, wherein the second gas flow passage extends through a first side region of the interstage stator portion about the exterior of the first aperture, and the third gas flow passageway is external to the second aperture. extending through a second side region of the peripheral interstage stator portion.
Stator assembly. According to claim 3,
wherein the second and third gas flow passages branch from the first gas flow passage and are fluidly connected to the first gas flow passage at both a beginning and an end.
Stator assembly. According to claim 3 or 4,
each of the second and third gas flow passages defining a generally C-shaped gas flow path around a respective one of the first and second apertures.
Stator assembly. The method according to any one of claims 1 to 5,
The stator assembly is formed of two stator halves connected to each other.
Stator assembly. According to claim 6,
The interstage stator portion is formed by two opposing generally W-shaped portions that are joined to each other when the two stator halves are connected to each other.
Stator assembly. According to claim 7,
wherein the plurality of gas flow passages are defined through the two generally W-shaped portions and are formed by a plurality of cavities each fluidly connected when the two generally W-shaped portions are joined together.
Stator assembly. The method according to any one of claims 1 to 8,
The interstage stator portion includes an inlet opening for receiving fluid from the first rotor stage and an outlet opening for transferring fluid from the interstage stator portion to the second rotor stage, wherein the plurality of gas flow passages include: disposed between an inlet opening and the outlet opening, fluidly connecting the inlet opening to the outlet opening.
Stator assembly. The method according to any one of claims 1 to 9,
The stator assembly includes a plurality of inter-stage stator portions.
Stator assembly. In the Roots vacuum pump,
a first rotor stage and a second rotor stage spaced apart along a longitudinal axis of the pump;
Comprising the stator assembly according to any one of claims 1 to 10,
wherein the interstage stator portion separates the first rotor stage from the second rotor stage along a longitudinal axis, and the plurality of gas flow passages receive fluid from the first rotor stage and deliver fluid to the second rotor stage. configured to
Roots vacuum pump. According to claim 11,
The pump further includes a pair of rotor shafts extending along a longitudinal axis, each rotor stage comprising first and second lobed rotors mounted to rotate with a respective one of the rotor shafts.
Roots vacuum pump. A method for transferring gas from a first rotor stage of a Roots vacuum pump to a subsequent second rotor stage, comprising:
providing a stator assembly having an interstage stator portion separating the first and second rotor stages;
and disposing a plurality of gas flow passages through the interstage stator portion configured to receive fluid from the first rotor stage and transfer fluid to the second rotor stage.
method. According to claim 13,
The plurality of gas flow passages include a first gas flow passage, a second gas flow passage, and a third gas flow passage,
The above method is,
defining the first gas flow passage through a central region of the interstage stator portion between two holes for receiving each rotor shaft;
defining the second gas flow passage through a first side region of the interstage stator portion around the first of the two apertures;
and defining the third gas flow passage through a second side region of the interstage stator portion around the second of the two apertures.
method. The method of claim 13 or 14,
the plurality of gas flow passages are defined by forming a plurality of cavities in each of two opposing stator halves,
The method further comprises coupling the stator halves together such that each of the plurality of cavities is fluidly connected to each other to form a respective gas flow passage of the plurality of gas flow passages.
method.