Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
PUMP BEARING LUBRICATION
Document Type and Number:
WIPO Patent Application WO/2018/211256
Kind Code:
A1
Abstract:
A lubricant transfer device (138) that transfers lubricant from a lubricant reservoir to a rolling bearing (132) in a pump. The lubricant transfer device (138) has a tapering outer surface (178) that has a downstream end (220). The lubricant transfer device (138) is mounted on a rotor shaft (124) supported by the rolling bearing (132). The rolling bearing (132) has a plurality of rolling elements (148) held by a cage (150). The lubricant transfer device (138) is arranged such that lubricant from the reservoir is fed along the outer surface (178) and distributed to a lubricant receiving surface (214) disposed outwardly of the cage on which surface the lubricant can flow under the influence of gravity towards a pilot land (152) of the cage (150).

Inventors:
LUCCHETTA, Emiliano (Edwards Limited, Innovation Drive, Burgess Hill Sussex RH15 9TW, RH15 9TW, GB)
PATEY, Alexander James (Edwards Limited, Innovation Drive, Burgess Hill Sussex RH15 9TW, RH15 9TW, GB)
Application Number:
GB2018/051307
Publication Date:
November 22, 2018
Filing Date:
May 15, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
EDWARDS LIMITED (Innovation Drive, Burgess Hill Sussex RH15 9TW, RH15 9TW, GB)
International Classes:
F16C33/66; F04D19/04; F04D29/059; F04D29/063; F16C19/06; F16N7/12; F16N7/36
Foreign References:
FR709853A1931-08-14
EP3001039A22016-03-30
EP0289897A11988-11-09
CH561367A51975-04-30
EP1903230A12008-03-26
Attorney, Agent or Firm:
NORTON, Ian (Edwards Limited, Innovation Drive, Burgess Hill Sussex RH15 9TW, RH15 9TW, GB)
Download PDF:
Claims:
Claims

1. A lubricant transfer device to be secured to a rotor shaft of a pump, wherein: said lubricant transfer device has a longitudinal axis and a tapering outer surface, said tapering outer surface has a downstream end and tapers radially outwardly with respect to said longitudinal axis towards said downstream end, and

said outer surface is provided with a plurality of lubricant discharge portions from which, in use, lubricant fed along said outer surface towards said downstream end is thrown radially outwardly with respect to said longitudinal axis towards respective separate lubricant receiving target areas.

2. A lubricant transfer device as claimed in claim 1, wherein in a direction along said longitudinal axis said plurality of lubricant discharge portions are spaced apart.

3. A lubricant transfer device as claimed in claim 1 or 2, wherein a first said lubricant discharge portion comprises an edge defined by said downstream end.

4. A lubricant transfer device as claimed in claim 1, 2 or 3, wherein a second said lubricant discharge portion comprises an edge defined by said outer surface that is spaced from said downstream end.

5. A lubricant transfer device as claimed in claim 4, wherein said second lubricant discharge portion comprises a plurality of said edges disposed in circumferentially spaced apart relation about said outer surface.

6. A pump comprising:

a rotor shaft;

a rolling bearing supporting said rotor shaft; and

a lubrication system to lubricate said rolling bearing,

wherein:

said rolling bearing comprises a cage having a pilot land and a plurality of rolling elements held by said cage, said lubrication system comprises a lubricant supply system comprising a lubricant reservoir and a lubricant transfer device to receive lubricant from said lubricant supply system,

said lubricant transfer device is mounted on said rotor shaft,

said lubricant transfer device has a longitudinal axis and a tapering outer surface, said tapering outer surface has a downstream end and tapers radially outwardly with respect to said longitudinal axis towards said downstream end, and

said outer surface is provided with a plurality of lubricant discharge portions from which, in use, lubricant fed along said outer surface towards said downstream end is thrown radially outwardly with respect to said longitudinal axis towards respective separate lubricant receiving target areas.

7. A pump as claimed in claim 6, wherein said lubricant discharge portions are disposed in respective planes that extend transverse to and through said longitudinal axis.

8. A pump as claimed in claim 6 or 7, wherein:

said rolling bearing further comprises an outer race and said pump is provided with a member adjacent said outer race that has a surface facing said rotor shaft, and

said plurality of lubricant discharge portions comprises a second lubricant discharge portion arranged to throw lubricant towards a second said lubricant receiving target area on said surface.

9. A pump as claimed in claim 6 or 7, wherein:

said rolling bearing further comprises an outer race comprising a radially inwardly facing surface, and

said plurality of lubricant discharge portions comprises a second lubricant discharge portion arranged to throw lubricant towards a second said lubricant receiving target area on said surface.

10. A pump as claimed in claim 8 or 9, wherein said rolling bearing and lubricant transfer device are orientated such that, in use, lubricant received on said second lubricant receiving target area flows downwardly along said surface towards said pilot land.

11. A pump as claimed in claim 8, 9 or 10, wherein in a direction along said longitudinal axis from said lubricant transfer device towards said rolling bearing said second lubricant target receiving area is disposed intermediate said second lubricant discharge portion and said pilot land.

12. A pump as claimed in claim 11, wherein in said direction along said longitudinal axis said second lubricant receiving target area is disposed intermediate said second lubricant discharge portion and said rolling elements.

13. A pump as claimed in 11 or 12, wherein said plurality of lubricant discharge portions comprises a first lubricant discharge portion arranged to throw lubricant at a first said lubricant receiving target area and in said direction along said longitudinal axis said first lubricant discharge portion is disposed intermediate said second lubricant receiving target area and said rolling elements.

14. A pump as claimed in claim 13, wherein said first lubricant discharge portion comprises an edge defined by said downstream end.

15. A pump as claimed in claim 13 or 14, wherein said first lubricant receiving target area is on at least one of a radially inwardly facing surface of said cage and said rolling elements radially inwardly of said cage.

16. A pump as claimed in any one of claims 8 to 15, wherein said second lubricant discharge portion comprises an edge defined by a discontinuity in said outer surface.

17. A pump as claimed in claim 16, wherein said second lubricant discharge portion comprises a plurality of said edges disposed in circumferentially spaced apart relation about said outer surface.

18. A pump as claimed in any one of claims 6 to 17, wherein said plurality of lubricant discharge portions comprises a lubricant discharge portion arranged to throw lubricant towards a lubricant receiving target area defined by said lubricant supply system so that said lubricant is returned to said lubricant supply system and not received by said rolling bearing.

19. A pump as claimed in claim 6 or 7, wherein said plurality of lubricant discharge portions and respective lubricant receiving target areas comprises a lubricant discharge portion arranged to throw lubricant towards a lubricant receiving target disposed radially inwardly with respect to said cage and at least one lubricant discharge portion arranged to throw lubricant towards a lubricant receiving target area disposed radially outwardly with respect to said cage.

20. A pump as claimed in claim 19, wherein said at least one lubricant discharge portion arranged to throw lubricant towards a lubricant receiving target area disposed radially outwardly of said cage comprises a lubricant discharge portion arranged to throw lubricant at a lubricant receiving target area defined by said lubricant supply system.

21. A pump as claimed in claim 19 or 20, wherein:

said rolling bearing comprises an outer race, and

said at least one lubricant discharge portion arranged to throw lubricant at a lubricant target area disposed radially outwardly of said cage comprises a lubricant discharge portion arranged to throw lubricant towards a lubricant receiving target area on a surface along which, in use, received lubricant flows towards an interface between said rolling elements and said outer race.

22. A method of providing lubricant transfer to a rolling bearing in a pump, wherein said rolling bearing comprises a cage having a pilot land and a plurality of rolling elements held by said cage and said method comprises:

providing a lubricant transfer device on a pump rotor shaft of said pump that is supported by said rolling bearing, wherein the lubricant transfer device has a longitudinal axis and an outer surface that has a downstream end and tapers outwardly with respect to said rotor shaft towards said downstream end; and

configuring said lubricant transfer device such that when, in use, said rotor shaft is rotated, a first portion of a lubricant flow fed along said tapering outer surface towards said downstream end is thrown outwardly of said lubricant transfer device from a first lubricant discharge portion onto a first lubricant receiving target area and a second portion of said lubricant flow is thrown outwardly of said lubricant transfer device from a second lubricant discharge portion onto a second lubricant receiving target area.

23. A method as claimed in claim 22, wherein said rolling bearing is orientated such that said lubricant flows downwardly from said second lubricant receiving target area towards said pilot land.

24. A method as claimed in claim 22 or 23, wherein said rolling bearing comprises an outer race and said second lubricant receiving target area is on:

i) said outer race; or

ii) a surface disposed adjacent said outer race and configured so that received lubricant flows from said second lubricant receiving target area to said outer race.

25. A method as claimed in any one of claims 22 to 24, wherein said first lubricant receiving target area is on a radially inner side of said cage or said rolling elements radially inwardly of said cage.

26. A method as claimed in any one of claims 22 to 25, wherein said pilot land is on a radially outer side of said cage.

27. A method as claimed in any one of claims 22 to 26, further comprising configuring said lubricant transfer device such that a portion of said lubricant flow is thrown outwardly of said lubricant transfer device from a third lubricant discharge portion to a third lubricant receiving target area defined by a lubricant supply system that, in use, supplies said lubricant flow fed along said tapering outer surface of said lubricant transfer device.

28. A method of providing lubricant transfer to a rolling bearing in a pump, wherein said rolling bearing comprises a cage having an outer periphery that defines a pilot land and a plurality of rolling elements held by said cage and said method comprises:

providing a lubricant transfer device on a pump rotor shaft of said pump that is supported by said rolling bearing, wherein the lubricant transfer device has a longitudinal axis and an outer surface that has a downstream end and tapers outwardly with respect to said rotor shaft towards said downstream end; and

configuring said downstream end such that when, in use, said rotor shaft is rotated, at least a portion of a lubricant flow fed along said tapering outer surface towards said downstream end is thrown outwardly of said lubricant transfer device onto a lubricant receiving surface that with respect to said longitudinal axis is disposed radially outwardly of said rolling elements and along which said lubricant flows towards said pilot land.

29. A method as claimed in claim 28, wherein said rolling bearing is orientated such that said lubricant flows downwardly along said lubricant receiving surface towards said pilot land.

30. A method as claimed in claim 28 or 29, wherein said rolling bearing comprises an outer race and said lubricant receiving surface is defined by said outer race.

31. A method as claimed in claim 28 or 29, wherein said rolling bearing comprises an outer race and said lubricant receiving surface is disposed adjacent said outer race and configured so that received lubricant flows from said lubricant receiving surface to said outer race.

32. A method as claimed in any one of claims 28 to 31, wherein in a direction along said longitudinal axis from said lubricant transfer device towards said rolling bearing said rolling elements are disposed a first distance from said downstream end of said outer surface, said downstream end is configured to throw said lubricant onto a target area on said lubricant receiving surface that is disposed a second distance from said downstream end and said second distance is less than said first distance.

33. A method as claimed in claim 32, wherein in said direction along said longitudinal axis said pilot land is disposed intermediate said target area and said rolling elements.

34. A method as claimed in any one of claims 28 to 33, further comprising providing said tapering outer surface with at least one discontinuity configured to cause a portion of said lubricant flow to be thrown outwardly of said lubricant transfer device onto a lubricant receiving target area defined by a lubricant supply system that, in use, supplies said lubricant flow fed along said tapering outer surface of said lubricant transfer device so that said portion of said lubricant flow is returned to said lubricant supply system and not received by said rolling bearing.

35. A pump compri sing :

a rotor shaft;

a rolling bearing supporting said rotor shaft; and

a lubrication system to lubricate said rolling bearing,

wherein:

said rolling bearing comprises a cage having an outer side that defines a pilot land and a plurality of rolling elements held by said cage,

said lubrication system comprises a lubrication supply system comprising a lubricant reservoir and a lubricant transfer device to receive lubricant from said lubricant supply system,

said lubricant transfer device is mounted on said rotor shaft,

said lubricant transfer device has a longitudinal axis and a tapering outer surface, said tapering outer surface has a downstream end and tapers radially outwardly with respect to said longitudinal axis towards said downstream end, and

said downstream end of said outer surface is configured to transfer said lubricant to a lubricant receiving surface that with respect to said longitudinal axis is disposed radially outwardly of said rolling elements so that received lubricant can flow along said lubricant receiving surface towards said pilot land.

36. A pump as claimed in claim 35, wherein said rolling bearing and lubricant transfer device are orientated such that said lubricant flows downwardly along said lubricant receiving surface towards said pilot land.

37. A pump as claimed in claim 35 or 36, wherein said rolling bearing further comprises an outer race and said lubricant receiving surface is defined by said outer race.

38. A pump as claimed in claim 35 or 36, wherein said rolling bearing further comprises an outer race and said pump is provided with a member that defines said lubricant receiving surface and is disposed adjacent said outer race.

39. A pump as claimed in any one of claims 35 to 38, wherein in a direction along said longitudinal axis from said lubricant transfer device towards said rolling bearing said rolling elements are disposed a first distance from said downstream end of said outer surface, said downstream end is configured to throw said lubricant onto a target area on said lubricant receiving surface that is disposed a second distance from said downstream end and said second distance is less than said first distance.

40. A pump as claimed in claim 39, wherein in said direction along said longitudinal axis said pilot land is disposed intermediate said target area and said rolling elements.

41. A pump as claimed in any one of claims 35 to 40, wherein said tapering outer surface of said lubricant transfer device is provided with at least one discontinuity configured to transfer a portion of said lubricant towards a lubricant receiving target defined by said lubricant supply system so that said portion of said lubricant is returned to said lubricant supply system and not received by said rolling bearing.

Description:
PUMP BEARING LUBRICATION

Field of the Invention

The invention relates to pump bearing lubrication and particularly, but not exclusively, to lubricating rolling bearings in inverted turbomolecular vacuum pumps.

Background to the Invention

Referring to Figure 1, it is known to support a rotor shaft 10 of a turbomolecular vacuum pump using a rolling bearing 12 located at or towards the lower end of the rotor shaft. The upper end of the rotor shaft 10 may be supported by a magnetic bearing (not shown). The rolling bearing 12 is lubricated with oil that is fed into the bearing by an oil feed nut 14 that is secured to the rotor shaft. The oil feed nut 14 tapers outwardly as it approaches the rolling bearing 12 so as to have a frusto-conical shape. In use, oil that is fed onto the outer surface 16 of the rotating oil feed nut 14 migrates along the nut towards the rolling bearing 12. At the downstream end 18 of the oil feed nut 14, oil is flung from the outer surface 16 by centrifugal force, thus transferring the oil into the rolling bearing 12 to lubricate the balls 22 and bearing cage 24.

The bearing cage 24 is piloted on a cage pilot land 26 defined by its outer diameter. The cage pilot land 26 is disposed radially outwardly, or outboard, of the balls 22 in face to face relation with the outer race and below the balls 22. In the example shown in Figure 1, the downstream end 18 of the oil feed nut 14 is disposed within the rolling bearing 12 adjacent the inner race 20 so that the oil flung into the bearing is delivered in the proximity of the balls 22. At least some of the oil delivered into the vicinity of the balls 22 by the feed nut 14 passes through the cage 24 from where it flows between the cage pilot land 26 and outer race 28 of the rolling bearing under the influence of gravity before returning to the oil supply reservoir (not shown). The oil film formed on the cage pilot land 26 provides support and stability for the cage 24, limiting wear and vibration. The lubrication system shown in Figure 1 works well in a range of orientations between the orientation shown in Figure 1 in which the rotor is mounted in an upright condition such that the oil feed nut 14 is located towards the bottom of the pump up to a position in which the rotor is mounted horizontally. However, if the orientation is such that the rotor is moved much above the horizontal, the lubrication system becomes less effective. This is because the influence of gravity causes the oil to flow away from the pilot land 26. This effect is most pronounced in the orientation shown in Figure 2 in which the pump is inverted as compared with the 'normal' upright arrangement shown in Figure 1 and the balls 22 are below the cage pilot land 26. It can be seen that the oil travelling towards the outer race 28 will flow away from the pilot land 26 under the influence of gravity making this configuration of rolling bearing 12 and oil feed nut 14 unsatisfactory for use in inverted pumps.

Summary of the Invention

The invention provides a lubricant transfer device as specified in claim 1. The invention also includes a pump as specified in claim 6.

The invention also includes a method of providing lubricant transfer to a rolling bearing in a pump as specified in claim 22.

The invention also includes a method of providing lubricant transfer to a rolling bearing in a pump as specified in claim 28.

The invention also includes a pump as specified in claim 35.

Brief Description of the Drawings

In the following disclosure, reference will be made to the drawings, in which:

Figure 1 is a schematic illustration of part of a known pump oil feed nut delivering oil to a rolling bearing; Figure 2 shows the oil feed nut and rolling bearing of Figure 1 in an inverted condition; Figure 3 is a schematic illustration of a turbomolecular pump in an inverted condition; Figure 4 is a cross section view of a lubrication system of the turbomolecular vacuum pump of Figure 3; Figure 5 is an enlarged schematic illustration of a rolling bearing and a lubricant transfer device from the turbomolecular pump shown in Figures 3 and 4;

Figure 6 is an enlargement of a portion of Figure 5; Figure 7 is a schematic illustration generally corresponding to Figure 5 showing an alternative rolling bearing and a lubricant transfer device;

Figure 8 is a schematic side elevation showing a modification of the lubricant transfer device of Figure 7;

Figure 9 is a schematic section view showing a modification of the lubricant transfer device of Figure 8;

Figure 10 is a schematic view showing the lubricant transfer device of Figure 7 arranged to deliver lubricant to a rolling bearing that has a cage piloted on its inner diameter;

Figure 11 shows the lubricant transfer device and rolling bearing of Figure 10 turned through 180°; and Figure 12 is a schematic representation of a modification to the lubricant transfer device illustrated by Figures 4 and 5.

Detailed Description

Referring to Figure 3, a turbomolecular pump 110 comprises a housing 112, a pumping mechanism 114 disposed in the housing, an inlet 116 and an outlet 1 18. The pumping mechanism 114 may comprise a turbomolecular pumping mechanism comprising a plurality of rotor blades 120 disposed in interleaving relationship with a plurality of stator discs 122, The rotor blades 120 may be mounted on, or integral with, a rotor shaft 124 that has a longitudinal axis (axis of rotation) 126. The rotor shaft 124 is driven to rotate about the axis of rotation 126 by a motor 128. The pumping mechanism 1 4 may additionally comprise a molecular drag pumping mechanism 130, which may be a Gaede mechanism, a Hoiweck mechanism or a Siegbahn mechanism. There may be additional, or alternative, mechanisms downstream of the molecular drag pumping mechanism such as an aerodynamic pumping mechanism comprising a regenerative mechanism.

The rotor shaft 124 is supported by a plurality of bearings 132, 134. The plurality of bearings may comprise two bearings 132, 134 positioned at, or adjacent, respective ends of the rotor shaft 124 as shown in Figure 3, or alternatively, intermediate the ends. In the example illustrated by Figure 3, a rolling bearing 132 supports a first end portion of the rotor shaft 124 and a magnetic bearing 134 supports a second end portion of the rotor shaft 124. A second rolling bearing may be used as an alternative to the magnetic bearing 134. When a magnetic bearing 134 is used, a back-up rolling bearing (not shown) may optionally be provided. With reference to a datum 135 extending transverse to the longitudinal axis 126 and bisecting that axis at a location intermediate the bearings 132, 134, when the turbomoiecuiar pump 1 10 is in an inverted condition, the rolling bearing 132 is disposed above the datum 135. Although not essential, in the illustrated example, the longitudinal axis 126 is disposed perpendicular to the datum 135 and the rolling bearing 132 is disposed towards the top of the turbomoiecuiar pump 110 and the bearing 134 is towards the bottom of the pump.

The turbomoiecuiar pump 110 additionally comprises a lubrication system to lubricate the rolling bearing 132. The lubrication system may comprise a lubricant supply system 136 and a lubri cant transfer devi ce 138 provided on the rotor shaft 24 to transfer lubri cant from the lubricant supply system to the rolling bearing 132.

Referring to Figures 4 and 5, the rolling bearing 132 is provided between the first end portion of the rotor shaft 124 and a bearing housing 142 of the turbomoiecuiar pump 110. The bearing housing 142 may be integral with the housing 112 or a component fitted to the housing as shown in Figure 4. As best seen in Figure 5, the rolling bearing 132 comprises an inner race 144 fixed relative to the rotor shaft 124, an outer race 146 fixed relative to the bearing housing 142, a plurality of roiling elements 148 disposed between the inner and outer races and a cage 150 that is configured to provide a desired spacing between the rolling elements. The cage 150 is piloted on its outer diameter so that the cage pilot land 152 is disposed in face-to-face relation with the outer race 146. The cage pilot land 152 may comprise an annular surface, which in the orientation of the pump 110 shown in Figures 4 to 6 is disposed above the rolling elements 148. The rolling bearing 132 is configured to allow relative rotation of the inner and outer races 144, 146 so that it can support the rotor shaft 124 during rotation of the rotor shaft relative to the housing 112. The rolling bearing 132 is supplied with a lubricant from the lubricant supply system 136 to establish a load-carrying film that minimises friction and wear in the bearing and provides support for the cage 150 by separating the rolling elements 148 from the inner and outer races 144, 146 and the cage and the cage pilot land 152 from the outer race. The lubricant is liquid and may be an oil.

As best seen in Figure 4, the lubricant supply system 136 may comprise a lubricant reservoir body 154-1, 54-2, one or more fingers 156 projecting inwardly of the lubricant reservoir body to engage the lubricant transfer device 138 and one or more lubricant return rnembersl 58, In use, lubricant from the lubricant reservoir 154-1 , 154-2 flows to the lubricant transfer device 138 via the one or more fingers 156 and lubricant that has passed through the rolling bearing 132 is returned to the lubricant reservoir via the one or more lubricant return members 158. The or each finger 156 and the or each lubricant return member 158 may be connected by an integral body member 160. For the sake of simplicity, in the description that follows, reference will be made to just one finger 156 and one lubricant return member 158, although, it is to be understood that this is not to be taken as limiting.

The lubricant supply system 136 may further comprise a collection channel 168 that is configured to receive lubricant that has been supplied to the roiling bearing 132 via the lubricant transfer device 138 and then passed through the bearing. The collection channel 168 has a downstream end 170 and an upstream end. The upstream end 174 of the lubricant return member 158 may be disposed at or adjacent the downstream end 170 of the collection channel 168 to receive and return lubricant from the collection channel 168 to the lubricant reservoir body 154-1, 154-2. Although not essential, in some examples, an absorbent collector body 176 may be disposed in the collection channel 168. The lubricant reservoir body 154-1 , 154-2, finger 156, lubricant return member 158, body member 160 and collector body 176 (when provided) may be made of a stable fibrous material or materials that are able to conduct lubricant by a capillary or wi eking action. The fibrous material may be natural or synthetic and in some examples may be a felt material. The lubricant reservoir body 154-1, 154-2, finger 156, lubricant return member 158 and body member 160 may be made of the same fibrous material, although in some examples different fibrous materials may be used. Although not essential, one or both body portions 154-1, 154-2 of the lubricant reservoir body may comprise a plurality of relatively thin layers of fibrous material stacked one upon another as shown in Figure 4. Referring to Figures 4 and 5, the lubricant supply system 136 may comprise a deflector 178 mounted on the rotor shaft 124. The deflector 178 may comprise a drip former 180 (Figure 5) to prevent the flow of lubricant along the underside of the deflector (as viewed in Figure 5) towards the rotor shaft 124. As shown, the drip former 180 comprises a depending annular skirt, although, it may take many other forms such as an annular groove in the underside of the deflector. The deflector 178 may be mounted on the rotor shaft 124 such that the rolling bearing 132 is disposed between the deflector and the lubricant transfer device 138. The positioning of the deflector 178 is such that lubricant that has passed through the rolling bearing 132 may impinge on the deflector. The deflector 178 is configured to deflect lubricant that has passed through the rolling bearing 132 into the collection channel 168. The deflector 178 may be seated on a shoulder 184 defined by a reduced diameter section of the rotor shaft 124. The shoulder 184 may be disposed adjacent a bore 186 provided in a partition 188 that separates the pumping mechanism 114 and motor 128 from the rolling bearing 132. The partition 188 may be an integral part of the housing 112 or an element fitted into and secured to the housing 112. The deflector 178 is configured to shield the bore 186 against the ingress of lubricant that has passed through the rolling bearing 132 and deflect, or divert, the lubricant into the collection channel 168. In the illustrated examples the deflector 178 is mounted on the rotor shaft 124. In some examples, a deflector may be provided on rolling bearing, for example on the inner race.

Referring to Figure 4, the lubricant supply system 136 may comprise a holder 190, 194 to hold the lubricant reservoir body 154-1, 154-2, lubricant member 158 and body member 160 in an assembled condition. The holder 190, 194 may comprise a main holder body 190 configured to receive the reservoir body 154-1 , 154-2 and body member 160 and a return member holder body 194 that may be integral with the main holder body 190, secured to the main holder body or disposed in the turbomoiecular vacuum pump 1 10 such that it abuts the inner end of the main holder body. The return member holder body 94 may be an elongate body defining a lengthways extending channel 196 configured to receive and support the lubricant return member 158. Although not essential, the holder 190, 194 may comprise one or more plastics mouldings. The holder 190, 194 may be received in a recess 200 provided at an end of the housing 112. The inner end of the recess 200 may be at least in part defined by the partition 188. The rolling bearing 132 is housed in the recess 200. The holder 190, 194 may be held in place in the recess 200 by an end cap 202 that may be secured to the housing 112 by bolts 204, clamps, screws or any other suitable securing mechanism,

Further information concerning the example of a lubricant supply system 136 shown in Figure 4 can be found in the Applicant's co-pending United Kingdom No 1613464.5, the content of which is incorporated herein by reference. It is, however, to be understood that the lubricant supply system shown in Figure 4 is given purely by way of example to aid understanding of the invention and any other suitable lubricant supply system may be used to supply lubricant to the lubricant transfer device 138,

Referring to Figure 5, the lubricant transfer device 138 may comprise a hollow frusto- conical body secured to the rotor shaft 124. The lubricant transfer device 138 has a longitudinal axis that is coincident with the longitudinal axis 126 of the rotor shaft 124. The lubricant transfer device 138 has an outer surface 206 that tapers radially outwardly with respect to the longitudinal axis 126 as it approaches the rolling bearing 132. The rotor shaft 124 and lubricant transfer device 138 may be provided with male and female threads respectively to enable the lubricant transfer device to be screwed onto the rotor shaft in the manner of a nut. Alternatively, in some examples, the lubricant transfer device 138 may comprise a sleeve-like construction that is slid onto the rotor shaft 124 and secured to the rotor shaft by means of a nut, bolt, screw or other suitable securing means. In other examples, the lubricant transfer device may be a solid body provided with a male thread at one end to screw into a female thread provided in an end of the rotor shaft.

Referring to Figures 5 and 6, the inner and outer races 144, 146 of the rolling bearing 132 have respective ends 210, 212 that face in the general direction of the lubrication transfer device 138 and are the ends of the inner and outer races disposed closest to the lubricant transfer device 138. In the orientation of the pump 110 illustrated by Figures 3 to 6, the ends 210, 212 are the upper ends of the inner and outer races 114, 146. For ease of identification, in the description of Figures 5 and 6 that follows, the ends 210, 212 will be referred to as the upper ends, although, it is to be understood that this is not to be taken as limiting and which ends of the rolling bearing 132 are the upper ends will depend on the orientation of the pump 1 10.

Referring to Figures 5 and 6, the outer race 146 is longer, or taller, than the inner race 144 and in this example, a radially inwardly facing surface 214 of outer race defines a lubricant receiving target area 216 for lubricant thrown into the rolling bearing 132 by the lubricant transfer device 138. The lubricant receiving target area 216 may be disposed adjacent the upper end 212 of the outer race 146 in the region at which the outer race projects above the inner race 144 so that in a direction along the longitudinal axis 126 from the lubricant transfer device 138 towards the roiling bearing 132, the target area is disposed intermediate the upper end 210 of the inner race and the upper end of the outer race. The lower end of the target area 216 may be disposed at least substantially level with the upper end 226 of the cage 150 so that there is an at least substantially uninterrupted flow path between the downstream end 220 of the outer surface 206 of the lubricant transfer device 138 and the target area 216. Thus, in this example the lubricant receiving target area 216 is disposed intermediate the downstream end 220 of the lubricant transfer device 138 and the cage pilot land 152). In the direction along the longitudinal axis 126 from the lubricant transfer device 138 towards the rolling bearing 132, the cage pilot land 152 is disposed at least substantially intermediate the lubricant receiving target area 216 and the upper end, or top, of the rolling elements 148, or at least, the positions at which the rolling elements engage the outer race 144. Thus, lubricant delivered onto the target area 216 is able to flow generally downwardly along the inwardly facing surface 214 of the outer race 212 between the cage pilot land 152 and outer race.

As viewed in Figures 5 and 6, in the direction along the longitudinal axis 126 of the rotor shaft 124 from the upstream end 217 of the lubricant transfer device 138 towards the rolling bearing 132, the upper ends of the rolling elements 148 are disposed a first distance 218 from the downstream end 220 of the lubricant transfer device 138 and the lower end of the target area 216 may be disposed a second distance 222 from the downstream end 220 that is less than the first distance 218. The target area 216 is typically an annular band defined on the surface 214. In the above-mentioned direction along the longitudinal axis 126, the cage pilot land 152 extends over a range of distances that are at least substantially intermediate the first and second distances 218, 222, although in some examples, the cage pilot land may extend somewhat between the upper ends of the rolling elements to a position intermediate the upper ends of the rolling elements and the uppermost position at which the rolling elements engage the outer race 146.

In the illustrated example, the configuration of the inner and outer races 144, 146 and cage 150 is such that the downstream end 220 of the outer surface 206 of the lubricant transfer device 138 is disposed intermediate the upper end 212 of the outer race 146 and the upper end 226 of the cage so that there is an uninterrupted flow path for lubricant from the downstream end 220 of the outer surface 206 to the target area 216. The upper end 226 of the cage 150 may be inclined, or otherwise configured, to encourage the flow of lubricant into the gap between the inwardly facing surface 214 of the outer race 146 and the pilot land 152. For example, in the axial direction of the rotor shaft 124 away from the lubricant transfer device 138 and in the radially outwards direction of the rolling bearing 132, the end 226 m ay be inclined such that it slopes away from the downstream end 220 of the outer surface 206 towards the pilot land 152. Thus, the lubricant transfer device 138 is configured to throw lubricant onto a target area 216 on a lubricant receiving surface defined by the outer race 146 along which the lubricant can then flow under the influence of gravity to lubricate the cage pilot land 152 and the rolling elements 148 and lubricant falling, or splashing, onto the upper end 226 of the cage 150 will similarly tend to flow towards the cage pilot land 152 under the influence of gravity or be flung towards the target area 216 by centrifugal force.

In use, when the rotor shaft 124 rotates about the axis of rotation 126, lubricant transferred to the lubricant transfer device 138 via the finger 156 moves along the tapered outer surface 206 of the lubricant transfer device towards the downstream end 220. From the downstream end 220, the lubricant is flung radially outwardly of the lubricant transfer device 138 into the rolling bearing 132 and, primarily, onto the target area 216 on the inwardly facing surface 214 of the outer race 146. The lubricant received on the target area 216 moves along the surface 214 under the influence of gravity into the space between the outer race 146 and the pilot land 152 to provide lubrication for the roiling elements 148 and the cage 150. Lubricant that passes through the rolling bearing 132 impinges on the deflector 178, which deflects, or flings, the lubricant towards the collection channel 168, where it is absorbed by the collector body 176. The lubricant collected in the collector body 176 migrates to the downstream end 170 of the collection channel 168 by a capillary or wicking action and passes into the lubricant return member 158 via which it is returned to the lubricant reservoir body 154-1, 154-2. Thus, lubricant supplied to the roiling bearing 132 can be effectively returned to the lubricant reservoir body 154-1 , 154-2 for recirculation and an adequate supply of lubricant is provided between the pilot land 152 and outer race 146. Figure 7 shows another roiling bearing 132 and lubricant transfer device 138 for the turbomolecuiar pump 110. Parts shown in Figure 7 that are the same as or similar to parts shown in Figures 4 to 6 are assigned the same reference numerals and may not be described in detail again. The principal differences between the respective arrangements shown in Figures 5 and 7 are that there is a lubricant receiving target area external to the rolling bearing and that the lubricant transfer device is configured to provide multiple discharge flows directed at separate target areas. The provision of multiple discharge flows and different lubricant receiving target areas may allow different parts of the rolling bearing to have substantially independent lubricant supplies so that each can be ensured of an adequate supply of lubricant or the lubricant supply to a particular part of the rolling bearing can be tuned, In this example, the height, or length, of the inner and outer races 144, 146 is at least substantially the same. The upper ends 210, 212 of the inner and outer races 144, 146 may be disposed in the same plane. A lubricant receiving surface 240 defining a target area 216 external to the rolling bearing 132 is provided adjacent the outer race 146. With respect to the longitudinal axis 126 of the rotor shaft 124, the lubricant receiving surface 240 is disposed radially outwardly of the inwardly facing surface 214 of the outer race 146. Although, not essential, in the illustrated example the lubricant receiving surface 240 is disposed radially outwardly of the outer race 146. The lubricant receiving surface 240 may be defined by a part of the bearing housing 142. Alternatively, in other examples, the lubricant receiving surface 240 may be defined by a part of the pump housi ng, such as the partition 188, or a deflector fitted to the bearing housing 142 or pump housing 112. Although not essential, the lubricant receiving surface 240 may be configured such that it causes received lubricant to flow radially inwardly with respect to the longitudinal axis 126 as it flows along the lubricant receiving surface 240 towards the upper end 212 of the outer race 146. Accordingly, in the direction along the longitudinal axis 126 from the lubricant transfer device 138 towards the rolling bearing 132, the lubricant receiving surface 240 may be inclined radially inwardly with respect to the longitudinal axis.

The lubricant transfer device 138 is provided with a cut-out 242 in the outer surface 206 such that the downstream end 220 comprises first and second lubricant discharge portions 248, 250 disposed in different planes 244, 246 that each extend at right angles to the longitudinal axis 126 of the rotor shaft 124. In this example, the first lubricant discharge portion comprises an edge 248 and the second lubricant discharge portion comprises an edge 250. Although not essential, the lubricant transfer device 138 is configured such that the inner race 144 of the rolling bearing 132 is partially received within the lubricant transfer device. In particular, the upper end 210 of the inner race 144 is received within the lubricant transfer device 138. The first lubricant discharge edge 248 is configured to discharge lubricant into the rolling bearing 32 onto one or more lubricant receiving target areas that may comprise the radially inner side of the cage 150 or the rolling elements 148 at positions radially inwardly of the cage. The second lubricant discharge edge 250 is configured to discharge lubricant onto the lubricant receiving target area 216 on the lubricant receiving surface 240. If the lubricant transfer device 138 shown in Figure 7 is used with a rolling bearing 132 as shown in Figure 5, the second lubricant discharge edge 250 may direct lubricant at a lubricant receiving target on the radially inner face 214 of the outer race 146 similar to the target area 216 shown in Figure 5. Thus, the lubricant transfer device 138 may provide independent lubricant supplies to respective radially spaced apart locations separated by the cage 150 so that providing lubrication to both sides of the cage does not rely on the transfer of sufficient lubricant across the cage by the rolling elements 148.

Figure 8 shows a modification of the lubricant transfer device 138 shown in Figure 7. The lubricant transfer device 138 shown in Figure 7 comprises one cut-out 242, whereas the lubricant transfer device 138 shown in Figure 8 comprises a plurality of cut-outs, or openings, 242. The cut-outs 242 may be disposed in spaced apart relation about the circumference of the downstream end 220 of the outer surface 206. The cut-outs 242 divide the downstream end 220 so that the first lubricant discharge portion comprises a plurality of circumferentially spaced apart first lubricant discharge edges 248 separated from one another by respective cut-outs 242. In use, each first lubricant discharge edge 248 may discharge lubricant into the rolling bearing 132 onto the radially inner surface of the cage 150 or onto portions of the rolling elements 148 at positions radially inwardly of the cage. The second lubricant discharge portion comprises a plurality of circumferentially spaced apart second lubricant discharge edges 250 defined by the upstream, or inner, ends of the cut-outs 242. In use, the second lubricant edges 250 may discharge lubricant at a target area disposed radially outwardly of the cage 150, such as on the lubricant receiving surface 240 or, in examples using a rolling bearing 132 as shown in Figures 4 and 5, on the radially inwardly facing surface 214 of the outer race 146. The cut-outs 242 may have a generally- U-shaped profile so that the second lubricant discharge edges 250 are arcuate in profile. In some examples, one of more of the cut-outs 242 may be partial at their upstream ends so that a recess 242-1 is defined as illustrated by way of example in the right-hand cut-out in Figure 8. In the example shown in Figure 8, the cut-outs 242 defining the second lubricant discharge edges 250 extend from the downstream end 220 of the outer surface 206 of the lubricant transfer device 138 towards the upstream end 217 and are open at their downstream ends. Alternatively, or additionally, the second lubricant discharge edges 250 may be defined by- recesses 242 be spaced from the downstream end 220 as illustrated in Figure 9. In some examples in which the form of the recesses does not provide such a strongly defined edge as that shown in Figure 9, it may be desirable to provide respective grooves, or indentations, immediately downstream of the edge to more clearly define the edge and ensure separation of the lubricant from the lubricant transfer device 138 at the edge.

It will be understood that a lubricant transfer device 138 as shown in Figures 7 to 9, may be used in the so-called inverted orientation of the pump illustrated by those figures in which the rolling bearing 132 is above the datum 135 and the lubricant transfer device is above the rolling bearing. In use, a first portion of a supply of lubricant flowing along the outer surface 206 may be thrown into the rolling bearing 132 from the first lubricant discharge edge, or edges, 248 to a generally radially inwardly located target area, or areas, on the rolling bearing while a second portion of the lubricant flow may be thrown from the second lubricant discharge edge, or edges, 250 to a generally radially outwardly located target area, or areas, on the rolling bearing or external to the rolling bearing. In this way, a first supply of lubricant may be discharged directly to the rolling elements 148 at locations radially inwardly of the cage 150, or the radially inner side of the cage, to provide lubrication between the rolling elements and the inner race 144 and the cage and a second supply of lubricant may be directed to the outer race 146 or an external lubricant receiving surface 240 to flow into the space between the cage pilot land 152 and outer race. The respective flows of lubricant may be tuned by selection of the proportions of the first and second lubricant discharge portions 248, 250. Although, the lubricant transfer device 138 may advantageously be used with the turbomolecular pump 110 in the orientation shown in Figures 7 to 9, it may also be used in the non-inverted condition illustrated generally by Figure 1. In this case, lubricant from the first lubricant discharge edge 248 may be directed onto the radially inner side of the cage 150 or the rolling elements 148 radially inwardly of the cage while lubricant from the second discharge edge 250 may be directed towards the outer race 146. The lubricant directed towards the outer race 146 may then fall under the influence of gravity back towards the lubricant reservoir for recirculation and provide little or no actual lubrication for the rolling bearing. However, by selection of the proportions of the first and second lubricant discharge edge (or edges) 248, 250, the primary flow of lubricant from the first lubricant discharge edge, or edges, 248 can be tuned to a desired requirement. This may provide a more reliable means of obtaining a desired lubricant flow into the rolling bearing 132 than adjusting the dimensions of components of a wicking-type lubricant supply system to control the volume flow rate onto the lubricant transfer device 138.

Figures 1 to 9 all show arrangements in which the cage 150 of the rolling bearing 132 is piloted on its outer diameter. Figure 10 shows a lubricant transfer device 138 at least similar to the lubricant transfer device shown in Figure 7 arranged to transfer lubricant to a rolling bearing 132 having a cage 150 piloted on its inner diameter so that the cage pilot land 152 faces the inner race 144. In this arrangement, lubricant discharged from the first lubricant discharge edge 248 primarily provides lubrication to the respective interfaces between the inner race 144 and the rolling elements 148 and cage pilot land 152, while lubricant discharged from the second lubricant discharge edge 250 primarily provides lubrication to the interface between the rolling elements and the outer race 146. Accordingly, an adequate supply of lubricant to both the inner and outer parts of the rolling bearing 132 may be ensured.

Figure 10 shows the rolling bearing 132 and lubricant transfer device 138 in an inverted condition such that the rolling bearing 132 is disposed above the datum 135 and below the lubricant transfer device 138. Figure 11 shows the rolling bearing 132 and lubricant transfer device 138 of Figure 10 turned through 180°. In this orientation, the cage pilot land 152 is below the rolling elements 148 and the second lubricant receiving target area is below the rolling elements and the cage pilot land. Accordingly, the lubricant supplied from the second lubricant discharge edge 250 may provide little or no lubrication for the rolling bearing 132. However, as previously described, by appropriate selection of the proportions of the first and second lubricant discharge portions 248, 250, the primary flow of lubricant from the first lubricant discharge edge 248 can be tuned to provide a desired volume flow rate. This may provide a more reliable method of obtaining a desired lubricant flow rate than adjusting the composition of a wicking-type lubricant supply system. It will be understood that in the orientation of the turbomolecular pump illustrated by Figure 11 a deflector 178 is not needed, although, providing a deflector advantageously allows use in either of the orientations illustrated by Figures 10 and 11.

It will be understood that when used with rolling bearings in which the cage is piloted on its outer periphery, lubricant transfer devices employing the principles described and illustrated herein allow the provision of a lubricant supply directly to the outer race or a surface adjacent the outer race so that the interface between the pilot land and outer race is adequately lubricated and does not have to rely on migration of lubricant across the bearing. Thus, adequate of lubrication of the pilot land/outer race interface can be ensured when the pump is used in an inverted condition in which the lubricant transfer device is disposed above the rolling bearing. In examples, in which the lubricant transfer device can target individual supplies at separate targets, an adequate supply of lubricant can be provided to the cage pilot land/outer race interface regardless of the orientation of the pump. Thus, for example, such lubricant transfer devices can ensure the provision of an adequate supply of lubricant to the cage pilot land/outer race interface of rolling bearings with cages piloted on their outer periphery in either of the orientations shown in Figures 1 and 2. Advantageously, a lubricant transfer device that can divide the supplied lubricant flow into individual supplies discharged at separate target areas, the lubricant flow to the rolling bearing can be tuned to accommodate use in all orientations from vertical to horizontal. This is useful as sometimes wicking-type lubricant supply systems that deliver a dependable lubricant flow rate may deliver more lubricant than is actually required and satisfactorily trimming the flow by adjustment of structure or proportions of the lubricant supply system may be difficult to achieve.

Examples of lubricant transfer devices that divide a lubricant flow into lubricant supplies directed towards respective target areas associated with the rolling bearing may also be used advantageously in cases in which the cage is piloted on its inner periphery as shown by way of example in Figures 10 and 11. In examples such as that shown in Figure 10, a desired lubricant flow can be directed towards the pilot land/inner race interface regardless of the orientation of the pump. The flow directed outwardly of the cage and rolling elements may provide some useful additional lubrication for the interface between the rolling elements and outer race in cases in which the lubricant transfer device is above the rolling bearing. In examples in which the rolling bearing is above the lubricant transfer device, the supply of lubricant towards the outer race will provide little or no worthwhile lubrication. However, there are nonetheless advantages as compared with a conventional oil feed nut as the volume flow rate to the pilot land/inner face interface can be tuned to provide a desired volume flow rate. It will be understood that in examples such as those illustrated by Figures 7 to 11, the lubricant flow rates discharged from the first and second lubricant discharge portions can be adjusted by altering the width of the cut-outs, openings, recesses, in the outer surface of the lubricant transfer device. For example, referring to Figure 8, if width of the recesses is increased, the combined width of the respective second lubricant discharge edges will be increased, while the combined width of the first lubricant discharge edges will be decreased. In this way, the flow rate of the lubricant discharged by the second lubricant discharge portion may be increased while the flow rate discharged by the first lubricant discharge portion is decreased. In this example, the sum of the widths of the second lubricant discharge edges increases the circumferential extent of the second lubricant discharge portion while the circumferential extent of the first lubricant discharge portion may be decreased. In examples, such as that shown in Figure 9, the flow rates may be adjusted by varying the circumferential extent of the second lubricant discharge edges, without changing the circumferential extent of the first lubricant discharge edge. The first and second lubricant discharge portions may be defined by planar lubricant discharge edges located in respective spaced apart planes as is shown by way of example in Figures 7, 10 and 11. It is to be understood that this is not essential as the separately targeted lubricant discharges may be provided by non-planar discharge edges. For example, as shown in Figure 8, the second discharge portion may comprise a plurality of arcuate lubricant discharge edges. Furthermore, it is to be understood that while in practice providing two separate lubricant discharge flows is likely to be adequate for most purposes, in principle, additional discharge flows may be generated by, for example, having three lubricant discharge portions located in respective different planes. It will also be understood that the shape of the cut-outs, openings or recesses that define the lubricant discharge portions in the illustrated examples are purely examples and other shapes and configurations may be used. In principle, the first and second lubricant discharge portions may take the form of any suitable formation or formations that provide a discontinuity or discontinuities that cause lubricant to be thrown outwardly of the lubricant transfer device towards a selected lubricant receiving target area or target areas. Such discontinuities may comprise at least one of an opening, cut-out or recess or a combination thereof. In the illustrated examples the cages are contained at least substantially within a boundary defined by the peripheral surfaces of the rolling bearing. However, this is not essential as in some examples the cage may project outwardly beyond the ends of the inner and outer races. For example, referring to Figure 10, the upper end 210 of the inner race 144 may be at least substantially in the same plane as the upper end 212 of the outer race 146 and the cage 150 may project above the upper ends 210, 212. In this case, the first lubricant discharge edge 248 may direct a supply of lubricant onto a lubricant receiving target area on a portion of the radially inwardly facing side of the cage 150 that projects above the upper ends 210, 212 while the second lubricant discharge edge 250 may direct a supply of lubricant toward a lubricant target area disposed externally of the rolling bearing from where the received lubricant may flow into the rolling bearing, primarily to the interface between the outer race and the rolling elements.

In some of the illustrated examples, for example as shown in Figure 7, the inner race may be partially received within the lubricant transfer device. This is not essential and the lubricant transfer device and rolling bearings may be arranged such that rolling bearing is disposed at least substantially entirely externally of the lubricant transfer device.

It will be understood that although the lubricant transfer devices illustrated by Figures 5, 6 10 and 11 are shown supplying lubricant to a lubricant receiving target area on the outer race of the rolling bearing, they may instead direct lubricant to a lubricant receiving target area on a surface external to the rolling bearing such as that shown in Figure 7. Similarly, lubricant transfer devices as illustrated by Figures 7 to 9 may be used with a rolling bearing similar to the rolling bearings shown in Figures 5, 6, 10 and 11 and direct lubricant onto a lubricant receiving target area on the outer race of the rolling bearing rather than a surface external to the rolling bearing. For example, referring to Figure 7, a nut, sleeve, annular deflector or the like may be disposed above the outer race 146 to define a lubricant receiving surface disposed radially inwardly of the outer periphery of the outer race and such a surface may be at least in part aligned with the radially inwardly facing surface 214 of the outer race.

In examples in which the lubricant receiving surface targeted by the second lubricant discharge surface is disposed externally of the rolling bearing, the surface may be inclined or otherwise profiled to cause the lubricant to flow radially inwardly in the general direction of the rolling bearing as illustrated by way of example in Figure 7. However, this is not essential. The lubricant receiving surface may have any suitable shape and orientation and may, for example, be at least substantially parallel to the longitudinal axis 126.

It will be appreciated that lubricant transfer devices such as those illustrated by the drawings provide a supply of lubricant to at least one lubricant receiving target area disposed radially outwardly of the cage so that rolling bearing arrangements that may not be satisfactorily lubricated by an oil feed nut as illustrated in Figures 1 and 2. Thus for example, a rolling bearing arrangement as shown in Figures 4 to 6 may be adequately lubricated when is in an inverted orientation as shown in those drawings and in positions between that orientation and an orientation in which the longitudinal axis 126 of the rotor shaft is disposed at least substantially horizontally. Lubricant transfer devices such as those illustrated by Figures 7 to 11 provide greater flexibility and allow the possibility of providing adequate lubrication regardless of the orientation of the pump. Thus, the adequate lubrication may be provided in either of the orientations illustrated by Figures 10 and 11 and all orientations between them.

As previously described, lubricant transfer devices that have multiple lubricant discharge portions provide the possibility of tuning the amount of lubricant supplied to different areas of the bearing. In some examples, at least one lubricant discharge portion may be arranged to supply lubricant to a position at which the lubricant will provide little or no lubrication for the bearing. For example, in the arrangement shown in Figure 11, the lubricant supplied to the outer race 146 by the second lubricant discharge portion 250 will in the main fall away from the rolling elements 148 and cage 150 due to gravity. Thus, the first and second lubricant discharge portions 248, 250 may be configured so the first lubricant discharge portion 248 supplies a desired volume of lubricant into the rolling bearing 132 to lubricate the rolling bearing while the second lubricant discharge portion 250, at least primarily, directs excess lubricant to a target area from which the lubricant can return to the lubricant supply system 136 without substantially affecting the lubrication of the rolling bearing. In some examples, there may be one or more lubricant discharge portions that discharge lubricant upstream of the rolling bearing directly to the lubricant supply system such that the lubricant discharge portion, or portions, may return lubricant directly to the lubricant reservoir body or to a lubricant return path, such as one or more channels, via which lubricant is returned to the lubricant reservoir body. An example of this is shown in Figure 12, which shows how the arrangement illustrated by Figures 4 to 6 may be modified so that the lubricant transfer device 138 has a first lubricant discharge portion in the form of an edge defined by the downstream end 220 of the lubricant transfer device and a second lubricant discharge portion 250 comprising an edge, or respective edges, 206 defined by one or more recesses 242 provided in the outer surface 206 of the lubricant transfer device. The or each recess 242 may be configured to throw a desired volume of lubricant away from the lubricant transfer device 138 to a lubricant receiving target disposed upstream of the rolling bearing 132 such that a portion of the lubricant supplied to the lubricant transfer device from the lubricant supply system 136 does not reach the rolling bearing so that only a controlled amount of lubricant is transferred to the rolling bearing for lubrication purposes. As shown in Figure 12, the lubricant discharged by the second lubricant discharge portion 250 may be thrown at a lubricant receiving target on the lubricant reservoir body 154-1, 154-2 so that the lubricant is returned directly to the lubricant reservoir body. Alternatively, the second lubricant discharge portion 250 may direct lubricant to a lubricant receiving target in the form of a receptacle, for example an annular channel, provided adjacent the lubricant transfer device 138 from where the lubricant is returned to the lubricant reservoir body. It will be understood that the arrangements shown in Figures 7, 8 and 10 may similarly be provided with one or more lubricant discharge portions that operate in similar fashion to the second lubricant discharge portion 250 of Figure 12 so that each has at least three lubricant discharge portions.

The illustrated turbomolecular vacuum pumps have a rotor carrying shaft simply supported between two bearings (either mechanical or magnetic). Other turbomolecular pumps may have rotor shaft supported by bearings such that the rotor is cantilever supported. The bearings may be rolling bearings or a combination of rolling bearings and magnetic bearings as previously described. It is to be understood that the above described lubrication systems and deflectors may be applied to such turbomolecular pumps.

It is to be understood that while the illustrated examples have been described in connection with turbomolecular pumps, this is not to be taken as limiting. In principle the structures and methodology described and illustrated herein can be applied to the lubrication of rolling bearings in any form of pump.

In this specification certain features are identifies as 'first', 'second' or 'third'. It is to be understood that this is purely for identification purposes and is not to be taken as an indication that there are just one, two or three such features. For example a reference to a second lubricant receiving target area on the outer race of the bearing is not to be taken as a requirement that there are two target areas on the outer race, although in some examples there may be.