GB2598004A

GB2598004A - Vacuum pump tool

Info

Publication number: GB2598004A
Application number: GB2018679.7A
Authority: GB
Inventors: Derek Groves Terry
Original assignee: Edwards Ltd
Current assignee: Edwards Ltd
Priority date: 2020-07-07
Filing date: 2020-11-27
Publication date: 2022-02-16
Also published as: GB202018679D0; GB202010403D0; GB2596818A

Abstract

An extraction tool 100 for extracting a component (fig.2, 80) from a recess (fig.2, 90) of a vacuum pump enclosure e.g. in the headplate, comprising an extraction piece 110 with a jawed collet 130 at its distal end and an actuation piece 140 which extends around the extraction piece at the proximal end is capable of exerting a variable force upon the jaws to adjust the diameter of the collet. The pump component may be a wear sleeve or a seal. The collet jaws may comprise an alignment recess and/or a grip element (fig.5a, 170) which may be removable and or a lip or flange (fig.7b 210, 230). The extraction piece may comprise an elongate cylinder having a hollow portion. The actuation piece may be moveable along a longitudinal axis of the extraction piece. The actuation and extraction pieces may comprise threaded portions on their inner and outer surfaces respectively. The actuation piece may be tapered and/or the extraction piece may be tapered. A method of extracting a component from a pump enclosure using an extraction tool with a jawed collet and an actuation piece to adjust the diameter of the collet.

Description

VACUUM PUMP TOOL

FIELD OF THE INVENTION

The field of the invention relates to a vacuum pump tool.

BACKGROUND

Pumps, such as vacuum pumps, are known. These pumps are often employed as a component of a vacuum system to evacuate devices. Also, these pumps are used to evacuate fabrication equipment used in, for example, the production of semiconductors, food manufacture and packaging, the oil and gas industry, steel manufacture and similar.

Vacuum pumps may take various forms, some, for example, take the form of multi-stage positive displacement pumps employing intermeshing rotors in multiple vacuum chambers. Whatever the form of a positive displacement vacuum pump, it can be helpful to provide arrangements which substantially seal the vacuum pump mechanisms from an exterior environment thereby preventing leakage of processed fluid from the pump and preventing any ambient air from entering the pump. Similarly, it is typical for many of the mechanisms which drive a vacuum pump to be located outside a vacuum chamber. Those drive mechanisms are coupled to operational pieces of the vacuum pump via connectors and couplings provided on a vacuum chamber housing, for example, a vacuum chamber headplate or similar. Such approaches ensure that the integrity of any seal between a vacuum chamber and an exterior environment is not jeopardised and that the vacuum pump is likely to be able to function efficiently and require minimal maintenance.

Although construction of vacuum pumps in this manner provide advantages, it also results in shortcomings. Accordingly, it is desired to provide an improved 30 vacuum pump tool suited for use with vacuum pumps. -2 -

SUMMARY

According to a first aspect, there is provided: a vacuum pump component extraction tool for extracting a component from a recess of a pump enclosure within which the component is installed; the extraction tool comprising: an extraction piece dimensioned to be insertable into the enclosure recess and such that a proximal end is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and an actuation piece which extends around the extraction piece at the proximal end, configurable to actuate exertion of a variable force upon jaws of the collet to adjust the diameter of the collet.

Typically, a vacuum pump comprises an enclosure or housing. That enclosure may comprise a pumping chamber within which at least one or more rotors may be located. The rotors can operate together to cause positive displacement of a gas and achieve vacuum pumping within the pumping chamber. The rotors may be carried on spindles or drive shafts and which may themselves be carried on bearings. The bearings may be located within bearing apertures provided by a head plate. The drive shafts or spindles may extend from the pumping chamber, and through a pump housing, for example, a pump headplate. Those spindles may then be coupled or connected to a drive motor to allow operation of the vacuum pump. Seals are provided between the exterior environment and the internal mechanism of a vacuum pump at least by virtue of seals provided in the pump housing or pump head plate. Such seals help to prevent the drawing in of contaminants into the pumping chamber from the external environment.

The first aspect recognises that a problem with some vacuum pumps is that they have components which may need regular servicing or maintenance. Some of those components may be difficult to maintain without dismantling, or damaging, components which form part of an enclosure or housing of a vacuum pump chamber. Regular maintenance work on components which help to seal a vacuum pump may result in a need to fully dismantle, or dismantle partially, a -3 -vacuum pump in a manner which may lead to significant downtime and possible contamination of components within the vacuum pump chamber.

A tool in accordance with the first aspect may provide a mechanism for accessing and exerting appropriate removal force upon difficult to reach and/or difficult to grip vacuum pump components. For example, the first aspect may provide a vacuum pump wear sleeve extraction tool for extracting a wear sleeve from a recess of a pump head plate within which the wear sleeve is installed; the extraction tool comprising: an extraction piece dimension to be insertable into the head plate recess and such that a proximal end is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and an actuation piece which extends around the extraction piece at the proximal end, configurable to actuate exertion of a variable force upon jaws of the collet to adjust the diameter of the collet. A wear sleeve typically sits around a spindle, making its inner surface difficult to access, and within a recess and opening of a pump headplate, making its outer surface difficult to access. Nonetheless, a wear sleeve may require regular replacement, or removal to allow for regular replacement of an oil seal, access to which may be obstructed by a wear sleeve.

A tool in accordance with the first aspect may provide a mechanism for accessing and exerting appropriate removal force upon difficult to reach and/or difficult to grip vacuum pump components. For example, the first aspect may provide an oil catcher extraction tool for extracting a an oil catcher from a recess of a pump head plate within which the oil catcher is installed; the extraction tool comprising: an extraction piece dimension to be insertable into the head plate recess and such that a proximal end is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and an actuation piece which extends around the extraction piece at the proximal end, configurable to actuate exertion of a variable force upon jaws of the collet to adjust the diameter of the collet. An oil catcher typically sits near a wear sleeve and adjacent an oil seal. It has surfaces which -4 -are difficult to access, and it is located within the restricted environment within a recess and opening of a pump headplate. Nonetheless, an oil catcher may require regular removal to allow for regular replacement or to allow access to other components requiring replacement or removal.

The vacuum pump component for removal by the tool may comprise: a wear sleeve, an oil seal, or an oil catcher.

The recess of a pump enclosure may comprise a recess in a vacuum pump headplate. The recess may, however, comprise any recess in a pump enclosure io or housing within which a component to be extracted may be located.

The maximum inner diameter of the jawed collet may be dimensioned to allow the collet to fit over an outer circumference of the vacuum pump component to be extracted. Accordingly, the tool is dimensioned to have an external diameter, at least at the distal end, to allow it to be inserted into the recess, and an inner diameter, at least when the collet is not compressed, to allow the collet to fit over the external surface of a component to be extracted.

In some arrangements, the tool is dimensioned to have an external diameter, at least at the distal end, to allow it to be inserted into the recess, and an inner diameter, at least when the collet is not compressed, to allow the collet to fit over at least a portion or region of an external surface of a component to be extracted. The collet jaws may comprise an alignment recess to align engagement of an inner surface of the jaws with an outer surface of the vacuum pump component to be extracted. Accordingly, by assisting alignment with an outer surface of a component to be extracted, a tool may be more likely to exert a balanced, evenly distributed, force upon the component to be extracted, increasing the likelihood of successful component removal.

At least some of the collet jaws may comprise a lip or flange protruding radially inwardly from an inner surface. The lip may be located at the distal end of the -5 -collet jaw or may be offset from an end of the collet jaw. At least one opposing pair of collet jaws may include a lip or flange. All of the collet jaws may include a an inwardly extending lip or flange. Accordingly, where a component for extraction has an accessible surface with radial extent, the extraction tool includes a mechanism by which such a surface of a component to be extracted can be used to aid extraction. A tool may, for example, thereby be able to engage a surface of a component to be extracted, where a radially outer surface of a component to be extracted is unavailable or inaccessible. A tool which allows for engagement of a portion of the collet jaws with a radially extending io surface of a component can increase the likelihood of successful component removal.

At least some of the collet jaws may comprise a grip coating provided on an inner surface of the jaws. Such a grip coating may comprise, for example, diamond coating, to increase friction between the inner surface of the collet jaws and the component to be extracted. Other abrasive grit or abrasive material may be used to form the grip coating.

At least some of the collet jaws may comprise a grip texture provided or formed on an inner surface of the jaws. Such a grip texture or formations may comprise, for example, ridges or protrusions, to increase friction between the inner surface of the collet jaws and the component to be extracted.

At least some of the collet jaws may comprise a grip element configured to contact an outer surface of the vacuum pump component to be extracted before the inner surface of the jaws. Such extra grip elements may increase friction between the inner surface of the collet jaws and the component to be extracted. The grip elements may be removably attachable to the collet jaws. The grip elements may display wear over time and ensuring that they are removably attachable allows for replacement of those elements by a maintenance engineer without a need to replace an entire extraction tool. Furthermore, different grip elements may be suited to different components for extraction. Allowing such -6 -elements to be removably attachable ensures that appropriate grip may be selected for a variety of components. Allowing for a variety of grip elements may allow the tool to be used for a variety of components, since effective size of an inner diameter of the collet may be adjusted by the removable grip elements.

The extraction piece may comprise: a substantially elongate cylinder, having a hollow portion extending longitudinally from its distal end, the hollow portion having an inner diameter selected to allow the extraction tool to be located over a vacuum pump element extending from the recess. Accordingly, where a component is located around a spindle or other component, an end of which extends from the pump housing, the hollow portion may be locatable over that extending end.

The actuation piece may be moveable along the longitudinal axis of the extraction -15 piece to actuate exertion of the variable force upon the jaws of the collet to adjust the diameter of the collet. Accordingly, relative movement may cause gip and release of the extraction piece around a component to be extracted. The tool may be inserted, the collet constricted around the piece to be extracted by means of movement of the actuation piece relative to the extraction piece, the tool removed from the recess, whilst gripping the component to be extracted. The tool can then be reused, since reverse movement of the actuation piece relative to the extraction piece may allow the jaws of the collet to expand, releasing the component from the tool The actuation piece and extraction piece may comprise threaded portions on their inner and outer surfaces respectively and movement of the actuation piece along the threaded portion from the proximal and towards the distal end of the extraction piece forces the actuation piece over a portion of the extraction piece which compresses the jaws of the collet. The relative movement may be effected by sliding one piece relative to the other and providing a stop which prevents reverse movement until the stop is removed or released. -7 -

The actuation piece may comprise a tapered inner surface at the distal end thereof The tapered inner surface may be formed such that an exterior diameter of the actuation piece is constant, and a thickness of a wall at a distal end of the tapered inner surface is less than a thickness of a wall at a proximal end of the tapered inner surface. The extraction piece may comprise a tapered outer surface towards the distal end thereof. The tapered outer surface may be formed such that an interior diameter of the extraction piece is substantially constant, and a thickness of a wall at a distal end of the tapered outer surface is greater than a thickness of a wall at a proximal end of the tapered outer surface. The tapering or one or both of the surfaces of the extraction and actuation pieces may allow for the smooth, gradual and even application and removal of force to a component to be extracted from a recess.

One of the actuation piece and extraction piece may comprise a user grip portion at their distal end. That grip portion may allow a user to more effectively exert an axial removal force upon the extraction tool, whilst the collet jaws are engaging a component for extraction. The grip portion may comprise a textured portion on an outer surface of the actuation piece or extraction piece. The grip portion may comprise one or more grooves and/or protrusions provided on an outer surface of the actuation piece or extraction piece. Such arrangements may increase friction and/or purchase between a user's hand or other simple hand tool and the extraction tool, thereby aiding extraction of the component.

A second aspect provides a method of extracting a vacuum pump component from a recess of a pump enclosure within which the component is installed using an extraction tool; comprising: inserting an extraction piece into the enclosure recess and such that a proximal end of the extraction tool is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and actuating exertion of a variable force upon jaws of the collet to adjust the diameter of the collet using an actuation piece which extends around the extraction piece at its proximal end. -8 -

Accordingly, once the component is gripped by the jaws of the collet, the tool may be removed, with component, from the recess.

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, 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 reference to the accompanying drawings, in which: Figure 1 illustrates schematically a vacuum pump according to one arrangement; Figure 2 is a cross sectional view of a portion of a vacuum pump head plate; Figure 3a and Figure 3b are isometric views of an extraction tool according to one arrangement; Figure 4 is a cross sectional view of a portion of a pump head plate including an extraction tool such as the one shown in Figure 3; Figure 5a is an isometric view of an alternative extraction tool; Figure 5b is a cross sectional view of a vacuum pump head plate in which the extraction tool shown in Figure 5a is used; Figure Sc is an enlarged cross-sectional view of a portion of the extraction tool collet in the region of a wear sleeve; Figure 6a is an isometric view of an alternative extraction tool; Figure 6b is a cross sectional view of a vacuum pump head plate in which the extraction tool shown in Figure 6a is used; and Figure 6c is an enlarged cross-sectional view of a portion of the extraction tool collet in the region of a wear sleeve; -9 -Figure 7a is a cross sectional view of a portion of a pump head plate including a further alternative extraction tool; Figure 7b is an enlarged cross sectional view of a portion of the further alternative extraction tool collet in the region of an oil catcher; Figure 8a is an isometric view of a further alternative extraction tool such as that shown in Figures 7a and 7b; and Figure 8b is a cross sectional view of a further alternative extraction tool shown in Figure 8a.

DESCRIPTION OF THE EMBODIMENTS

Before discussing the embodiments in any more detail, first an overview will be provided.

Embodiments provide a tool which enables vacuum pumps to be serviced on site.

In particular, embodiments may provide a tool which enables, for example, a wear sleeve or seal to be removed from a vacuum pump housing, for example, from a head plate without a need to disassemble a vacuum pump enclosure. Removal of a component such as a wear sleeve may enable access to, and maintenance of, an oil seal. Use of a tool in accordance with embodiments may allow both an oil seal and wear sleeve to be maintained and/or replaced without the need to take apart a vacuum pump enclosure or housing, or to remove a vacuum pump head plate. Tools according to embodiments can, for example, allow for a wear sleeve to be removed from a spindle projecting from a pump enclosure or head plate and that removal can allow access to an oil seal. The tool allows a maintenance engineer to avoid dismantling the head plate from the pump. Such an arrangement ensures that any downtime associated with pump maintenance can be minimised.

VACUUM PUMP

Figure 1 illustrates schematically a cross section of a vacuum pump 10 according to one arrangement. A generic vacuum pump is shown, although it will be appreciated that the tool can be applied to various forms of vacuum pump -10 -including, for example, roots-type pumps, screw pumps, claw pumps, and similar. The pump 10 comprises a pumping chamber 20 having a fluid inlet 22 and fluid outlet 24. The pumping chamber is separated from some other primary components 50 of the vacuum pump and the external environment by a head plate 30. The pumping chamber 20 houses a set of lobed rotors 40 supported on a spindle 45. The spindle 45 is supported on bearings (not shown) located in the head plate 30. A motor and gears form part of the primary other components 50 of the pump 10. The gears can be attached to the spindle 45 to provide for required coupling, indicated conceptually by dashed line 55, of a motor to the spindle 45 and to ensure appropriate rotation of the rotors 40.

As pump 10 is operated the pressure in the pumping chamber 20 reduces as a fluid moves from inlet 22 to outlet 24. That pressure reduction can cause a pressure differential between the pumping chamber 20 and the other components 50 or external environment outside the head plate 30.

It will be appreciated that the spindle 45 extends through the vacuum chamber 20 and extends out of a vacuum pump rotor enclosure or housing. In particular, the spindle may extend through the pump head plate 30. The spindle 45 extends through the head plate 30 to enable coupling of a motor to the rotors in the pumping chamber.

HEAD PLATE

Figure 2 is an enlarged view of a portion of a vacuum pump head plate 30 in the vicinity of a spindle 45. The spindle emerges from the head plate and extends into the pumping chamber 20. It can be seen that a very tight tolerance exists between the outer surface of the spindle 45 and the opening 60 in the head plate 30. In order to secure a seal and to ensure longevity of a vacuum pump, often an oil seal 70 is provided and a wear sleeve 80 is provided on the spindle 45. It will be appreciated that the oil seal 70 and wear sleeve 80 together form a gas-tight seal between the vacuum chamber 20 and the exterior environment.

As can be seen in Figure 2, a recess 90 is formed in the face of the head plate 30 in the region where the spindle 45 extends through it. The recess 90 extends in a direction parallel to the axis of the spindle 45.

The wear sleeve 80 is provided to ameliorate wear of the spindle in the region where it passes through the headplate 30. It is typically constructed from a sacrificial material and wears preferentially to the spindle as the pump is used. The wear sleeve is a substantially cylindrical collar. A portion of wear sleeve 80 extends into the recess 90 from opening 60. The length of wear sleeve 80 which io extends into the recess 90 is small. The exterior surface area of the wear sleeve which is available to grip is therefore also small. As a result, extracting the wear sleeve 80 from the recess 90 of the head plate 30 is difficult without removing the head plate 30 from the vacuum pump 10, enabling removal of the spindle from the arrangement, and allowing more access to surfaces of the wear sleeve and then oil seal to enable removal of those parts. Removal of the head plate 30 from the vacuum pump 10 is a task that presents difficulties including significant processing downtime and compromise of the vacuum chamber 20.

Figures 3a and 3b are isometric views of an extraction tool 100 according to one arrangement. The extraction tool 100 shown allows extraction of a wear sleeve 80 located in an opening 60 provided in a recess 90 of a pump headplate 30. The wear sleeve 80 is installed around a pump spindle 45. The extraction tool of Figure 3 comprises: an extraction piece 110 dimensioned to be insertable into the headplate recess 90. That is to say, the outer diameter of the extraction piece to be inserted into the recess in the headplate or pump housing is less than the diameter of that recess. The extraction piece 110 is substantially cylindrical, or hollow, at least in the region or length which is to be inserted over the spindle 45 which extends out of the headplate 30. The extraction piece 110 has a proximal end 120 which is accessible at an entrance of the recess 90 when the extraction piece 110 is inserted into the recess. Being able to access the extraction piece when in position for extraction is important to allow operation of the extraction tool. The extraction piece 110 has a jawed collet 130 at its distal end. The jawed -12 -collet 130 comprises at least two "fingers" or "jaws" 135, separated by gaps 137. The tool 100 further comprises an actuation piece 140 which extends around the extraction piece 110 in the region of the proximal end 120. The actuation piece 140 is configurable to actuate exertion of a variable force upon jaws 135 of the collet 130 to adjust the effective inner diameter 145 of the collet 130. In the example shown in Figure 3a, the actuation piece 140 takes the form of a cylinder which fits over the inner extraction piece. The extraction piece 110 and actuation piece 140 are moveable relative to each other. That is to say, the actuation piece can be moved along the axis of the extraction piece. That movement is achieved, in the example shown, by means of cooperating screw threaded portions provided on the outer surface and inner surface of the extraction piece and actuation piece respectively. The outer surface of the actuation piece and inner surface of the actuation piece have tapered portions which interact to enable the diameter 145 of the fingers 135 to be reduced and thus a force to be exerted on, for example, a wear sleeve located within a headplate recess. In general a tool such as the one shown schematically in Figures 3a and 3b operates such that the contracting fingers 135 of the collet 130 grips against an outer diameter of, for example, a wear sleeve located in an opening within a recess of a pump headplate. The gripping force exertable on the wear sleeve by the collet fingers 135 allows the wear sleeve to be gripped by the extraction tool and thus, when the tool 100 is removed from the recess and around the spindle 145, the wear sleeve can be extracted from the opening in the head plate without the need to remove the head plate from a vacuum pump.

In some arrangements, such as the one shown in Figure 3, the fingers 135 can be compressed together as a result of a taper feature on the outside of the fingers and a cooperating corresponding taper provided on the inner surface of the outer sliding cylindrical portion. In the example shown schematically in Figure 3 when the outer cylindrical portion is forced along the length of the inner portion of the fingers, opposing tapers act to constrict the fingers and apply force between each fingertip and the outer surface of the wear sleeve. That force grips the wear sleeve and allows it to be extracted.

-13 -Figure 4 is a cross sectional view of a portion of a pump head plate 30 with an extraction tool in position. As shown in Figure 4, the extraction tool (such as one according to the arrangement shown in Figure 3) can be located over the spindle 45 which projects out of the head plate. The tool is dimensioned to fit into the recess in the head plate 30. The central orifice of the extraction tool may be dimensioned to be a slideable fit over the spindle 45 such that alignment of the tool along the access of the spindle 45 may be ensured.

As shown in Figure 4 the jaws or fingers 135 forming a collet at one end of the io extraction tool are dimensioned and shaped so that finger tips 139 are locatable close to an outer surface of a wear sleeve 80. The diameter between opposing fingertips 139 may be adjusted by appropriate movement of the outer activation piece portion 140 of the extraction tool in relation to the inner extraction piece portion such that the fingertips 139 of the collet engage with an outer surface of the wear sleeve 80. In the example shown in Figure 4, the inner and outer portions of the extraction tool are moved relative to one another by means of a screw arrangement 150. That is to say, the inner and outer portions have appropriate screw thread regions and rotational movement of the pieces along the threaded portions ensures that longitudinal movement of the actuation piece along the extraction piece occurs and that an outer tapered surface portion 160 of the extraction piece interacts with an inner tapered surface portion 162 of the actuation piece and that a force is exerted which moves the fingers 135 of the collet closer together. As a result, an inner radial force is exerted between the finger tips 139 of the extraction tool and an outer surface of the wear sleeve.

Once the fingertips grip the wear sleeve surface tightly enough, the tool can be slidably removed from along the spindle 45, taking the wear sleeve from opening 60 in the headplate 30. The tool can be reset or released by appropriate movement of the actuation piece along the extraction piece, using the threaded portions 150.

Figure 5a is an isometric view of an alternative extraction tool. The alternative extraction tool shown in Figure 5a is analogous to the tool shown in Figures 3a -14 -and 3b. However, the tool shown in Figure 5a includes additional tip inserts 170 provided at the end of the collet fingers. Those tip inserts 170 are shown on all of the fingers of the tool of Figure 5a, but it will be appreciated that a subset of fingers may be provided with tip inserts. The tip inserts 170 provide extra grip to the tool for gripping and extracting the wear sleeve as required. It can be seen, for example, in Figure 5c, that the extra tips 170 provided on the fingers ensure that the effective diameter of the collet is smaller than that provided by the fingers themselves and that a very small contact area is provided between the tool fingers and the outer surface of the wear sleeve, or other component to be extracted. Using a small area ensures that the pressure exerted by the extraction tool and the grip which occurs between a grip tip 175 of the tip inserts 170 and the wear sleeve can be increased. Furthermore, in the example shown in Figure 5a, the tip inserts 170 are removably located on the fingers of the collet by screws 180. As a result, any wear which occurs to the tip inserts 170, for example, erosion of grip tips 175, may be easily ameliorated by means of replacements of the tip inserts.

Figure 5b is a cross section of a portion of head plate and an extraction tool according to the arrangement shown in Figure 5a.

Figure Sc is an enlarged cross-sectional view of a portion of the collet of the extraction tool in use. Figure 5c shows a collet finger in the region of the wear sleeve where it can be seen that the grip tip 175 of the tip insert 170 provides a very small contact area with the wear sleeve, allowing extra grip to be applied to the wear sleeve to ensure extraction.

Figure 6a is an isometric view of an alternative extraction tool. In the arrangement shown in Figure 6a, grub screws 190 are provided to provide extra grip. The grub screws may be screwed through the fingers to provide a small tip of contact 195 which can engage with greater pressure with an external surface of a component to be extracted.

-15 -Figure 6b is a cross sectional view of a portion of head plate showing an extraction tool such as that in Figure 6a in position.

Figure 6c is an enlarged cross-sectional view of a portion of a collet in the region 5 of the wear sleeve. It can be seen that the grub screws 190 extend through the finger and provides extra grip points 195 to enable operation of the extraction tool when engaging with the outer surface of a wear sleeve. Furthermore, in the example shown in Figure 6, it will be appreciated that the grub screws are removably located on the fingers of the collet. As a result, any wear which occurs to the screw tips 195 may be easily ameliorated by means of replacement of the screws 190. Similarly, although grub screws are shown in all collet fingers, it is possible to provide a subset of the fingers with grub screws 190.

Figure 7a is a cross sectional view of a portion of a pump head plate including a further alternative extraction tool, and Figure 7b is an enlarged cross-sectional view of a portion of the further alternative extraction tool collet in the region of an oil catcher. Figure 7a shows a portion of a vacuum pump head plate 30 in the vicinity of a spindle 45. The spindle emerges from the head plate and extends into the pumping chamber 20. It can be seen that a very tight tolerance exists between the outer surface of the spindle 45 and an opening 60 in the head plate 30. In order to secure a seal and to ensure longevity of a vacuum pump, as described above, an oil seal 70 is provided and a wear sleeve 80 is provided on the spindle 45. The oil seal 70 and wear sleeve 80 together form a gas-tight seal between the vacuum chamber 20 and the exterior environment. The seal assembly can include further components, for example, an oil catcher 200. The form of oil catcher 200 is shown in greater detail in Figure 7b.

The oil catcher 200 is provided to limit and ameliorate spread of oil around the headplate 30. The oil catcher 200 is substantially annular, is typically configured to extend between an inner surface of a recess in headplate 30 and a wear sleeve 80, to contain any oil which may escape from oil seal 70. The oil catcher and includes an annular lip, or flange 210. The flange 210 does not extend to, or -16 -abut, an inner surface of a recess provided in the headplate 30. As a result, a the oil catcher includes a substantially annular groove or channel 220. The flange 210 essentially forms a lip with which an appropriately shaped extraction tool may be shaped to engage to allow extraction of the oil catcher from the head plate recess. It will be appreciated that extracting the oil catcher 200 from a recess in the head plate 30 can be difficult, without an appropriate tool, since access to a surface or portion of the oil catcher on which an extraction force can be exerted is limited.

An extraction tool configured for such a purpose is shown in Figures 7a and 7b, whilst in situ within a head plate 30 recess. The extraction tool of Figure 7a and 7b comprises: an extraction piece 110 dimensioned to be insertable into the headplate recess. That is to say, the outer diameter of the extraction piece to be inserted into the recess in the headplate or pump housing is less than the diameter of that recess. The extraction piece 110 is substantially cylindrical, or hollow, at least in the region or length which is to be inserted over the spindle 45 which extends out of the headplate 30. The extraction piece 110 has a proximal end 120 which is accessible at an entrance of the recess when the extraction piece 110 is inserted into the recess. Being able to access the extraction piece when in position for extraction is important to allow operation of the extraction tool. The proximal end of the extraction piece includes a grip portion 125 which is shaped to allow a user to exert an effective pulling force on the extraction tool. In the arrangement shown in Figure 7a the grip portion includes an annular groove 126 formed in the outer surface of the extraction piece 110. Inclusion of annular groove 126 creates a lip or protrusion 127, against which a user can exert a force to pull the extraction tool away from the headplate. It will be appreciated that rather than forming a groove and thereby creating a protrusion on the outer surface of the extraction piece, it would be possible to form the extraction piece 110 such that, in the region of its proximal end 120, a user grip protrusion is included.

-17 -The extraction piece 110 has a jawed collet 130 at its distal end. As described in relation to other arrangements, the jawed collet 130 comprises at least two "fingers" or "jaws", separated by gaps. As shown in Figure 7a and in more detail in Figure 7b, one or more of the jaws or fingers include a lip 230 which projects radially inwardly. In the illustrated arrangement, the lip 230 is dimensioned such that the fingers can, if the collet is open, be inserted into a headplate recess and extend past a portion of an outer surface of an inaccessible component, before the collet is contracted so that the lip 230 is locatable behind flange 210 and within groove 220. The diameter between opposing fingertips may be adjusted by appropriate movement of the outer activation piece portion 140 of the extraction tool in relation to the inner extraction piece portion such that the lip 230 of the collet engages with groove 220. In the example shown in Figure 7a and Figure 7b, the lip 230 is formed at the end of the collet jaw fingertips 139. It will be appreciated, however, that depending upon the form of the component to be extracted, the lip 230 can be recessed such that it is axially offset from the very end of the collet jaw fingertips.

As a result, an inner radial force is exerted between the finger tips 139 of the extraction tool and an outer surface of the wear sleeve. Once the fingertips grip the wear sleeve surface tightly enough, the tool can be slidably removed from along the spindle 45, taking the wear sleeve from opening 60 in the headplate 30. The tool can be reset or released by appropriate movement of the actuation piece along the extraction piece, using the threaded portions 150.

The tool 100 further comprises an actuation piece 140 which extends around the extraction piece 110 in the region of the proximal end 120. The actuation piece 140 is configurable to actuate exertion of a variable force upon jaws of the collet to adjust the effective inner diameter of the collet. In the example shown in Figure 7a and 7b, the actuation piece 140 takes the form of a cylinder which fits over the inner extraction piece. The extraction piece 110 and actuation piece 140 are moveable relative to each other. That is to say, the actuation piece can be moved along the axis of the extraction piece. That movement is achieved, in the -18 -example shown, by means of cooperating screw threaded portions provided on the outer surface and inner surface of the extraction piece and actuation piece respectively. The outer surface of the actuation piece and inner surface of the actuation piece have tapered portions which interact to enable the diameter between inner surfaces of opposing fingers to be reduced, an "open" region between opposing fingers to be contracted, and thus a force to be exerted on, for example, a portion of the oil catcher 200 located within a headplate recess.

As described above, a tool such as the one shown schematically in Figure 7a operates such that the contracting fingers of the collet 130 are configured to engage with, or hook, finger lip 230 around a portion of an inaccessible or limited access component, for example, an oil catcher, located in an opening within a recess of a pump headplate. In other words, the fingers of the extraction tool may be dimensioned or shaped to include a portion which can engage and/or abut a radially extending surface of a component, and thereby allow an extraction force to be exerted upon that component surface having radial extent.

The gripping force exertable on a portion of the inaccessible component by the collet fingers allows the component to be firmly gripped by the extraction tool and thus, when the tool 100 is removed from the recess, the component can be extracted from the opening in the head plate without the need to remove the head plate from a vacuum pump.

Figure 8a is an isometric view of the further alternative extraction tool such as that shown in Figures 7a and 7b; and Figure 8b is a cross sectional view of the further alternative extraction tool shown in Figure 8a. It can be seen that all of the fingers of the extraction tool include a lip 230, but it will be appreciated that a similarly effective extraction tool could be formed provided one or more opposite pairs of fingers included such a lip. As described above, a tool such as that shown in Figure 8 works by providing a contractable finger arrangement at a distal end. The fingers are dimensioned to hook behind a diametral shoulder of a component, for example, an oil catcher, allowing for that component to be -19 -extracted from its working position within a recess of a pump headplate. The fingers of the tool are contracted or compressed as a result of provision of cooperating taper features on an outer surface of one or more of the fingers and a co-operating taper provided on an inside surface of a ring which is axially moveable along the fingers. When the ring is moved along the fingers, the opposing tapers are configured to apply a force radially inwards upon the fingers. That force reduces a diameter between opposing pairs of fingers, and allows lip 230 to hook behind a surface having radial extent of the component to be removed and allows the component to be extracted if an appropriate axial force is applied to the tool, for example by exertion of an axial force against user grip protrusion 127.

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 equivalents. For example, whilst cooperating screw threads are described to implement movement of the extraction portion in relation to the actuation portion, it is possible for actuation to be achieved in other ways, for example linear movement, such as co-operating wedges, can be used to move the actuation piece along the extraction piece and therefore force engagement of the tapered portions, causing the inner diameter of the collet fingers to reduce.

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REFERENCE SIGNS

vacuum pump pumping chamber 22 pumping chamber inlet 24 pumping chamber outlet pump headplate pump rotors spindle other components of vacuum pump io 55 coupling between spindle and motor opening in headplate oil seal wear sleeve recess in headplate 100 extraction tool extraction piece extraction piece proximal end extraction piece grip portion 126 annular groove 127 user grip protrusion extraction piece jawed collet collet jaws 137 gaps between jaws 139 collet jaw fingertips 140 actuation piece inner diameter of collet cooperating screw arrangement 160 tapered surface of extraction piece 162 tapered surface of actuation piece 170 tip inserts grip tip of tip insert fastening screws -21 -grub screws grip points oil catcher 210 oil catcher flange 220 oil catcher annular groove 230 finger lip

Claims

-22 -CLAIMS1. A vacuum pump component extraction tool for extracting a component from a recess of a pump enclosure within which the component is installed, the extraction tool comprising: an extraction piece dimensioned to be insertable into the enclosure recess and such that a proximal end is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and io an actuation piece which extends around the extraction piece at the proximal end, configurable to actuate exertion of a variable force upon jaws of the collet to adjust the diameter of the collet.
2. A vacuum pump component extraction tool according to claim 1, wherein the vacuum pump component comprises: a wear sleeve.
3. A vacuum pump component extraction tool according to claim 1, wherein the vacuum pump component comprises: a seal.
4. A vacuum pump component extraction tool according to claim 1, wherein the vacuum pump component comprises: an oil catcher.
5. A vacuum pump component extraction tool according to any preceding claim wherein the recess of a pump enclosure comprises: a recess in a vacuum pump headplate.
6. A vacuum pump component extraction tool according to any preceding claim, wherein a maximum inner diameter of the jawed collet is dimensioned to allow the collet to fit over an outer circumference of the vacuum pump component to be extracted.
-23 -A vacuum pump component extraction tool according to any preceding claim, wherein a maximum inner diameter of the jawed collet is dimensioned to allow the collet to fit over at least a portion of an outer surface of the vacuum pump component to be extracted.
8. A vacuum pump component extraction tool according to any preceding claim, wherein the collet jaws comprise an alignment recess to align engagement of an inner surface of the jaws with an outer surface of the io vacuum pump component to be extracted.
9. A vacuum pump component extraction tool according to any preceding claim, wherein at least some of the collet jaws comprise a lip or flange protruding radially inwardly from an inner surface.
10. A vacuum pump component extraction tool according to any preceding claim, wherein at least some of the collet jaws comprise: a grip element configured to contact an outer surface of the vacuum pump component to be extracted before the inner surface of the jaws.
11 A vacuum pump component extraction tool according to claim 1, wherein the grip element is removably attachable to the collet jaws.
12. A vacuum pump component extraction tool according to any preceding claim, wherein the extraction piece comprises: a substantially elongate cylinder, having a hollow portion extending longitudinally from its distal end, the hollow portion having an inner diameter selected to allow the extraction tool to be located over a vacuum pump element extending from the recess.
13. A vacuum pump component extraction tool according to any preceding claim, wherein the actuation piece is moveable along the longitudinal axis -24 -of the extraction piece to actuate exertion of the variable force upon the jaws of the collet to adjust the diameter of the collet.
14. A vacuum pump component extraction tool according to claim 10, wherein the actuation piece and extraction piece comprise threaded portions on their inner and outer surfaces respectively and movement of the actuation piece along the threaded portion from the proximal and towards the distal end of the extraction piece forces the actuation piece over a portion of the extraction piece which compresses the jaws of the collet.
15. A vacuum pump component extraction tool according to any preceding claim, wherein the actuation piece comprises a tapered inner surface at the distal end thereof.
16. A vacuum pump component extraction tool according to claim 12, wherein the tapered inner surface is formed such that an exterior diameter of the actuation piece is constant, and a thickness of a wall at a distal end of the tapered inner surface is less than a thickness of a wall at a proximal end of the tapered inner surface.
17. A vacuum pump component extraction tool according to any preceding claim, wherein the extraction piece comprises a tapered outer surface towards the distal end thereof.
18. A vacuum pump component extraction tool according to claim 14, wherein the tapered outer surface is formed such that an interior diameter of the extraction piece is substantially constant, and a thickness of a wall at a distal end of the tapered outer surface is greater than a thickness of a wall at a proximal end of the tapered outer surface.
19. A vacuum pump component extraction tool according to any preceding claim, wherein one of the actuation piece and extraction piece comprises a user grip portion at their distal end.
-25 - 20. A vacuum pump component extraction tool according to claim 19, wherein the user grip portion comprises one or more grooves located on an outer surface of the actuation piece or extraction piece.
21. A vacuum pump component extraction tool according to claim 19 or claim 20, wherein the user grip portion comprises one or more protrusions located on an outer surface of the actuation piece or extraction piece.io
22. A method of extracting a vacuum pump component from a recess of a pump enclosure within which the component is installed using an extraction tool; comprising: inserting an extraction piece into the enclosure recess and such that a proximal end of the extraction tool is accessible at an entrance of the recess when the extraction piece is inserted into the recess, the extraction piece having a jawed collet at its distal end; and actuating exertion of a variable force upon jaws of the collet to adjust the diameter of the collet using an actuation piece which extends around the extraction piece at its proximal end.