Vacuum pump gas turret

Abstract

A vacuum pump gas turret for coupling a gas motor with a vacuum pump comprises a coupling body 200 for conveying a gas from the gas motor to a supply pipe. The coupling body defines a conduit 250 havi

Description

FIELD OF THE INVENTION The present invention relates to a gas turret. 5 BACKGROUND Gas turrets are known. Gas turrets are a coupling which typically couples between a gas supply and a gas supply conduit. For example, a gas turret may couple between a gas motor and a gas supply pipe to convey a gas between the 10 gas motor and the supply pipe. Although gas turrets are useful, they may have unexpected shortcomings. Accordingly, it is desired to provide an improved gas turret. SUMMARY 15 According to a first aspect, there is provided a vacuum pump gas turret for coupling a gas motor with a vacuum pump, comprising: a coupling body for conveying a gas from the gas motor to a supply pipe, the coupling body defining a conduit having an inlet portion having an inlet internal cross-sectional area, an outlet portion having an outlet internal cross-sectional area smaller than the inlet 20 internal cross-sectional area and a transition portion between the inlet portion and the outlet portion having a transition internal cross-sectional area which transitions between the inlet internal cross-sectional area and the outlet internal cross-sectional area; and a supply pipe received by the coupling body and configured to receive the gas from the outlet portion and conveyed to the vacuum 25 pump. The first aspect recognizes that a problem with existing gas turrets is that they can cause back pressure sensors to be activated, which activates a warning of a potential blockage which in turn can cause the operation of downstream 30 equipment receiving the gas from the gas motor to be suspended while a potential blockage is investigated. This is because the shape and / or configuration of the gas turrets can cause a wide variation in the back pressure generated by the gas turret dependent upon how it is located in the gas supply. Accordingly, a vacuum pump gas turret or coupling is provided. The vacuum pump gas turret may be for coupling a gas motor or supply with a vacuum pump. The vacuum pump gas turret may comprise a coupling body or structure for 5 conveying a gas from the gas motor. The coupling body may define or provide a conduit. The conduit may have or provide have an inlet portion or region. The inlet portion may have or define an inlet internal cross-sectional area. The conduit may have or define an outlet portion or region. The outlet portion may have or define an outlet internal cross-sectional area which is smaller than or 10 reduced compared to the inlet internal cross-sectional area. The conduit may have or provide a transition portion or region. The transition portion may be located between the inlet portion and the outlet portion. The transition portion may be downstream of the inlet portion. The outlet portion may be downstream of the transition portion. The transition portion may have or define a transition 15 internal cross-sectional area which transitions, changes or varies between the inlet cross-sectional area and the outlet cross-sectional area. The vacuum pump gas turret may comprise a supply pipe. The supply pipe may be configured or arranged to be received by, coupled with or engaged with the coupling body. The supply pipe may be configured or arranged to receive the gas from the outlet 20 portion for conveying to the vacuum pump. In this way, the inlet portion may be provided with a larger internal cross-sectional area than the outlet internal cross-sectional area which increases the fluid conductance of the gas turret and helps to reduce back pressure, which reduces the likelihood of any back pressure sensors being activated which, in turn, reduces any blockage alarms and reduces 25 the likelihood of the operation of any downstream apparatus from being suspended. The transition internal cross-sectional area of the transition portion may narrow, reduce or constrict from the inlet portion to the outlet portion. The transition internal cross-sectional area of the transition portion may narrow or reduce from the inlet internal cross-sectional area to the outlet internal cross-sectional area. 5 The transition internal cross-sectional area of the transition portion may taper. The inlet internal cross-sectional area of the inlet portion may have or define a constant, unchanging or the same internal cross-sectional area along a first axial length. 10 The internal cross-sectional area of the inlet portion may substantially match or be the same as an internal cross-sectional area of a gas supply conduit of the gas motor. 15 The inlet internal cross-sectional area of the inlet portion may substantially match or be the same as a cross-sectional area of a stream of the gas from the gas motor. Matching the cross-sectional areas enables the flow of the gas stream to be captured by the gas turret, helps to increase gas conductance of the gas turret and reduces back pressure. 20 The outlet internal cross-sectional area of the outlet portion may have a constant, unchanging or the same internal cross-sectional area along a second axial length. 25 An external diameter of a first portion or region of the coupling body may be dimensioned and / or configured to fit an internal diameter of a coupling recess of the gas motor. In other words, the first portion of the coupling body may be sized to be received within the coupling recess. 30 The first portion may include the inlet portion. The first portion may further include the transition portion. An axial length of the coupling body may be dimensioned and / or configured to abut, touch or rest against an end face of the coupling recess. This helps to provide for uniform positioning of the gas turret within the coupling recess. 5 The inlet internal cross-sectional area of the inlet portion may substantially match or equal a cross-sectional area of a stream of gas from the gas motor flowing into the coupling recess. Matching the cross-sectional areas helps to increase gas conductance of the gas turret and reduce back pressure that may be measured 10 by back pressure sensors. The inlet portion may be dimensioned and / or configured to define an axial end face which fails to interfere with or block the flow of a flow of the stream of the gas from the gas motor flowing into the coupling recess. Again, this helps to 15 increase gas conductance of the gas turret and reduce back pressure that may be measured by back pressure sensors. An external diameter of a second portion of the coupling body may be dimensioned to fit an internal diameter of the supply pipe. 20 The second portion may include the outlet portion. According to a second aspect, there is provided an apparatus comprising the vacuum pump gas turret of the first aspect and at least one of the gas motor and 25 the vacuum pump. The apparatus may comprise all the features of the vacuum pump gas turret set out above. 30 Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims. Where an apparatus feature is described as being operable to provide a function, 5 it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described further, with 10 reference to the accompanying drawings, in which: FIG. 1 illustrates schematically an arrangement of a conventional gas turret located within a gas supply conduit of a gas motor; FIG. 2 illustrates a coupling body of a gas turret according to one embodiment; FIG. 3 shows an axial cross-sectional view through the coupling body of FIG. 2; 15 and FIGS. 4 and 5 illustrates the gas turret of FIG 2. with an O-ring seal positioned within the supply conduit of the gas motor. DESCRIPTION OF THE EMBODIMENTS 20 Before discussing the embodiments in any more detail, first an overview will be provided. Some embodiments provide a vacuum pump gas turret or coupling structure which couples a supply of gas with a vacuum pump. The coupling structure defines a conduit having an enlarged inlet opening compared to a narrower outlet opening. The conduit narrows between the inlet opening and the 25 outlet opening. The coupling structure has a supply pipe which couples with the vacuum pump. This provides for improved gas conductance compared with conventional arrangements. FIG. 1 illustrates schematically an arrangement of a conventional gas turret 100 30 located within a gas supply conduit 110 of a gas motor 120. The gas turret 100 has a coupling body whose outside diameter matches generally with an internal diameter of the gas supply conduit 110 and an O-ring seal 130 which fluidly seals any gap between the gas turret 100 and the gas supply conduit 110. The gas turret 100 is placed within the gas supply conduit 110 and the gas motor 120 supplies gas to the gas supply conduit 110, which is conveyed via the gas turret 100 to a downstream apparatus (not shown). However, a problem with the 5 arrangement shown in FIG. 1 is that pressure sensors (not shown) within the gas motor 120 can activate, indicating a blockage in the gas flow from the gas motor 120 depending on the configuration and / or positioning of the gas turret 100 FIG. 2 illustrates a coupling body 200 of a vacuum pump gas turret according to io one embodiment. The coupling body 200 comprises a first portion 210 and an adjacent second portion 220. The first portion 210 defines a generally cylindrical external surface having an annular recess 230 shaped and configured to receive an O-ring seal (not shown). The first portion has a chamfered region 240 at an axial end of the first portion 210 distal from the second portion 220. The first 15 portion 210 has an external diameter dimensioned to fit the internal diameter of the gas supply conduit 110. An external surface of the second portion 220 is also generally cylindrical and has an external diameter dimensioned to fit an internal diameter of a supply pipe (not shown). The external diameter of the second portion 220 is smaller than the external diameter of the first portion 210 to 20 accommodate a thickness of the supply pipe. FIG. 3 shows an axial cross-sectional view through the coupling body 200. As can be seen, the coupling body 200 defines a conduit 250. The conduit 250 comprises an inlet portion 260 adjacent a downstream transition portion 270 25 which, in turn, is adjacent a downstream outlet portion 280. The inlet portion 260 of the conduit 250 is generally cylindrical in shape and has an internal diameter Di which is larger than an internal diameter D2 of the outlet portion 280. The outlet portion 280 of the conduit 250 is also generally cylindrical in shape. The transition portion 270 of the conduit 250 is shaped to transition between the 30 diameters Di and D2. In this example, the transition portion 270 is frustoconical but it will be appreciated that the internal surface of the transition portion 270 may be stepped or curved. FIG. 4 illustrates the vacuum pump gas turret 300 comprising the coupling body 200 and an O-ring seal 130 positioned fully within the supply conduit 110 of the gas motor 120. The internal diameter D2 of the outlet portion 280 of the conduit 5 250 has been dimensioned so that the second portion can be accommodated within an internal diameter of the supply pipe (not shown). The internal diameter Di of the inlet portion 260 of the conduit 250 is selected to be larger than the diameter D2. Typically, the diameter Di is dimensioned to match a diameter of a gas supply aperture 140 of the gas motor 120 which supplies the gas supply 10 conduit 110 with gas. In other words, the diameter Di is dimensioned to have a cross-sectional area which substantially matches a cross-sectional area of the gas stream supplied by the gas motor 120 through the gas supply aperture 140 and into the gas supply conduit 110 to improve its conductance. As can be seen in FIG. 4, an axial end of the first portion 110 abutting an end of the gas supply 15 conduit 110 fails to interfere with or obstruct the flow of the gas stream into the gas supply conduit 110. Also, the first portion 210 has an axial length dimensioned to enable the gas turret 300 to be fully recessed into the gas supply conduit 110 and abut against an annular shoulder 150 defining one end of the gas supply conduit 110. The gas is supplied from the gas motor 120, through the 20 gas supply aperture(s) 140 to the inlet portion 260 of the conduit 250, is conveyed to the downstream transition portion 270 of the conduit 250, into the downstream outlet portion 280 of the conduit and into the supply pipe for supply to the vacuum pump (not shown). FIG.5 illustrates the vacuum pump gas turret 300 (with the O-ring seal 130 omitted for clarity) being positioned within the 25 entrance of the supply conduit 110 of the gas motor 120 prior to being locating at the position shown in FIG. 4. Hence, as can be seen, the gas turret 300 has increased conductance compared to the conventional gas turret 100. Also, it can be fully received into the gas 30 supply conduit 110 without substantially interfering with the gas flow from the gas motor 120. This enables the gas turret 300 to be placed consistently within the gas supply conduitl 10 without resulting in the variations in back pressure experienced with the conventional gas turret 100 and avoids any pressure sensors being activated which may otherwise indicate a blockage. This provides for a more reliable and consistent coupling to the gas motor than the arrangement shown in FIG. 1 which typically requires adjustment of the 5 positioning of the gas turret 100 and / or adjustment of pressure thresholds of the pressure sensors based on the individual positioning of that gas turret 100. Accordingly, some embodiments provide a nozzle shape gas turret for conductance improvement. This helps to reduce pressure deviation regardless io of the gas turret position in the gas module by improving its conductance. As mentioned above, in some situations, the exhaust pressure changes depending upon the particular position of a conventional gas turret, which makes it hard to identify by-product blockage degree. Typically, with the conventional gas turret design, the exhaust pressure changes dependent on assembly position in the 15 gas module. This means that exhaust pressure change dependent on how the pump is built. This causes a problem because user might misunderstand that byproduct is created whereas the change is simply due to individual gas turret positioning. Also, this leads to less margin for exhaust pressure warning / alarm setpoint and measurable range of a pressure sensor. In particular, in some 20 circumstances the exhaust pressure was not uniform and could range from 2.7~4.1 psig. Also, there was not much margin for exhaust pressure warning / alarm set point (9.01 / 14 psig) and pressure sensor’s rated pressure range (-14.7 ~ 14.7 psig). For example, just a little by-product creation could easily cause a warning / alarm. In addition, there was less margin for measurable pressure 25 range of the pressure sensor (measurable pressure range in some circumstances can be from -1 barg to 1 barg). A cause of this variation was conductance. With a conventional gas turret, when it was deeply inserted into the gas module, the exhaust pressure increased. When the gas turret was moved slightly out of the gas module, the exhaust pressure decreased. This means that conductance 30 changed with gas turret position. To be specific, with a conventional gas turret of FIG. 1, the right side area of the gas turret acts like a wall interfering with, for example, N2 flow which leads to an increasing number of molecules existing near the pressure sensor. To decrease the deviation caused by the gas turret position and make more margin for the exhaust pressure warning I alarm setpoint and measurable pressure sensor range, the conductance of the gas turret was improved by designing a nozzle-shape gas turret. The improved conductance 5 results in just a slight exhaust pressure change as the gas turret assembly position changes. This design minimizes possibility of gas flow interference and achieved an exhaust pressure of around 2 psig, with a deviation of was less than around 1 psig. Hence, the gas turret design of some embodiments can secure more margin for exhaust pressure warning I alarm and for pressure sensor io measurable range. Embodiments are particularly suited to pumps having increased flows as to the exhaust pipe as they have improved conductance. Embodiments are also particularly suited to situations where the pressure sensor and gas purge system exists in one space. 15 Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their 20 equivalents. REFERENCE SIGNS Gas turret 100 Gas supply conduit 110 5 Gas motor 120 O-ring seal 130 Gas supply aperture 140 Annular shoulder 150 Coupling body 200 io First portion 210 Second portion 220 Annular recess 230 Chamfered region 240 Conduit 250 15 Inlet portion 260 Transition portion 270 Outlet portion 280 Vacuum pump gas turret 300

Claims

1. A vacuum pump gas turret for coupling a gas motor with a vacuum pump, comprising:5 a coupling body for receiving a gas from said gas motor, said couplingbody defining a conduit havingan inlet portion having an inlet internal cross-sectional area, an outlet portion having an outlet internal cross-sectional area smaller than said inlet internal cross-sectional area andio a transition portion between said inlet portion and said outlet portionhaving a transition internal cross-sectional area which transitions between said inlet internal cross-sectional area and said outlet internal cross-sectional area; anda supply pipe received by said coupling body and configured to receive15 said gas from said outlet portion and conveyed to said vacuum pump.

2. The vacuum pump gas turret of claim 1, wherein said transition internal cross-sectional area of said transition portion narrows from said inlet portion to said outlet portion.

203. The vacuum pump gas turret of claim 1 or 2, wherein said transition internal cross-sectional area of said transition portion narrows from said inlet internal cross-sectional area to said outlet internal cross-sectional area.25 4. The vacuum pump gas turret of any preceding claim, wherein saidtransition internal cross-sectional area of said transition portion tapers.

5. The vacuum pump gas turret of any preceding claim, wherein said inlet internal cross-sectional area of said inlet portion has a constant internal cross-30 sectional area along a first axial length.

6. The vacuum pump gas turret of any preceding claim, wherein said inlet internal cross-sectional area of said inlet portion substantially matches an internal cross-sectional area of a gas supply conduit of said gas motor.5 7. The vacuum pump gas turret of any preceding claim, wherein said inletinternal cross-sectional area of said inlet portion substantially matches a cross-sectional area of a stream of said gas from said gas motor.

8. The vacuum pump gas turret of any preceding claim, wherein said outlet io internal cross-sectional area of said outlet portion has a constant internal cross-sectional area along a second axial length.

9. The vacuum pump gas turret of any preceding claim, wherein an external diameter of a first portion of said coupling body is dimensioned to fit an internal 15 diameter of a coupling recess of said gas motor.

10. The vacuum pump gas turret of claim 9, wherein said first portion includes said inlet portion.20 11. The vacuum pump gas turret of claim 9 or 10, wherein said first portionfurther includes said transition portion.

12. The vacuum pump gas turret of any one of claims 9 to 11, wherein an axial length of said coupling body is dimensioned to abut against an end face of said 25 coupling recess.

13. The vacuum pump gas turret of any one of claims 9 to 12, wherein said inlet internal cross-sectional area of said inlet portion substantially matches a cross-sectional area of a stream of said gas from said gas motor flowing into said 30 coupling recess.

14. The vacuum pump gas turret of any one of claims 9 to 13, wherein said inlet portion is dimensioned to define an axial end face which fails to interfere with a flow of said stream of said gas from said gas motor flowing into said coupling recess.

515. The vacuum pump gas turret of any preceding claim, wherein an external diameter of a second portion of said coupling body is dimensioned to fit an internal diameter of said supply pipe and said second portion includes said outlet portion.io

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