CN215333490U

CN215333490U - Pump bearing lubricant supply system

Info

Publication number: CN215333490U
Application number: CN201990000786.3U
Authority: CN
Inventors: R·G·霍尔勒; M·韦尔马
Original assignee: Edwards Ltd
Current assignee: Edwards Ltd
Priority date: 2018-06-14
Filing date: 2019-06-13
Publication date: 2021-12-28
Anticipated expiration: 2029-06-13
Also published as: GB2574648A; DE212019000313U1; WO2019239138A1; GB201809751D0

Abstract

A pump includes a pumping mechanism having a rotor shaft (124) with an axis of rotation (126). The rotor shaft is supported for rotation by a plurality of bearings including a rolling bearing (132) having an outer periphery (136). The pump further comprises a lubricant supply system (148) and a lubricant transfer device (150) arranged on the rotor shaft to transfer lubricant from the lubricant supply system to the rolling bearing. The lubricant supply system comprises a lubricant reservoir (152) and a lubricant return system (156) by which lubricant leaving the rolling bearing is returned to the lubricant reservoir. The lubricant return system includes a lubricant return passage (158) having an upstream end (174) and extending from the upstream end beyond an outer periphery (136) of the rolling bearing and configured such that, in use, lubricant is movable in an upward direction in the lubricant return passage by capillary action.

Description

Pump bearing lubricant supply system

Technical Field

The present invention relates to pump bearing lubricant supply systems and more particularly, but not exclusively, to lubrication of bearings in turbomolecular pumps.

Background

Many pumps include an impeller (impeller) in the form of a rotor mounted on a rotor shaft and a stator surrounding the rotor. The rotor shaft is supported by a bearing arrangement, which may comprise two bearings located at or intermediate respective ends of the shaft. One or both of these bearings may be rolling bearings. The upper bearing may be in the form of a magnetic bearing and the lower bearing may be in the form of a rolling bearing. Such an arrangement may be used in a vacuum pump, such as for example a turbo molecular vacuum pump.

A typical rolling bearing includes: an inner race fixed relative to the rotor shaft; an outer race fixed relative to a support structure (e.g., a pump housing); and a plurality of rolling elements located between the races to facilitate relative rotation of the inner and outer races. To prevent mutual contact between the rolling elements, they are often guided and evenly spaced by a cage. Proper lubrication is necessary to ensure accurate and reliable operation of the rolling bearing. The main purpose of the lubricant is to create a carrier film which separates the bearing components in rolling and sliding contact in order to minimize friction and wear. Other purposes include preventing oxidation or corrosion of the bearing components, forming a barrier to contaminants, and transferring heat away from the bearing components. The lubricant is usually in the form of oil or grease (a mixture of oil and thickener).

Pumps that use oil-lubricated bearings require an oil feed system to feed oil between the contact areas of the bearings to enable the oil to cool and lubricate the bearings. This facilitates operation at high rotational speeds. Turbomolecular vacuum pumps have traditionally used a wicking system for supplying oil to the rolling bearings. In such systems, a felt wick (felt wick) supplied from an oil reservoir feeds oil to a conical "oil feed" nut mounted on the shaft. The oil reservoir may comprise two stacks of felt layers placed against the respective major surfaces of the felt wick such that the felt wick is sandwiched between the two stacks. In use, as the shaft rotates, oil travels up the conical surface of the nut to the bearing. The oil then passes through the bearings and is returned to the reservoir under the influence of gravity. If the pump is not designed or oriented so that the bearings are above the reservoir, return of lubricant to the reservoir can be problematic, particularly in so-called inverted pump arrangements, where the reservoir is above the bearings so that the returning oil must flow upward against gravity.

US2008/0112660 discloses a turbomolecular pump in which the rotor shaft is supported by an upper bearing and a lower bearing. The rotor blades, stator and pump motor are positioned at a location intermediate the two bearings. The rotor blades and the stator are positioned relatively closer to the upper bearing, and the pump motor is positioned below and relatively closer to the lower bearing. The upper bearing may be a magnetic bearing and the lower bearing may be a rolling bearing. The rolling bearing is part of a module comprising a retainer which is push-fitted into a fitting recess provided in the pump housing to accurately position the rolling bearing relative to the rotor shaft. The rolling bearing is supplied with oil from a lubricant reservoir via an oil feed nut. An oil feed nut is mounted on the rotor shaft. The lubricant reservoir is made of an absorbent material, such as felt, and is mounted in a holder together with the rolling bearing. The lubricant reservoir includes an extension rod, also made of an absorbent material, which extends from the reservoir over the outer periphery of the rolling bearing. The extension rod extends parallel to the rotor shaft and has an upstream end portion positioned above and on one side of the rolling bearing. Radial delivery means are positioned above or adjacent the upper end of the rolling bearing to deliver oil that has passed through the rolling bearing to the extension rod. The extension rod must securely engage the body of the lubricant reservoir to ensure that oil transfer between the two can occur. The radial delivery means comprises a slot formed between the upper end of the retainer and the pump housing or between the two halves of a two-piece retainer. The groove is configured to cause oil it receives from the rolling bearing to flow radially outward from the rotor shaft into the upstream end of the extension rod. With the aid of suitable spacers, the grooves are dimensioned such that oil flows along the grooves to the extension rod under the action of capillary forces. The returned oil then flows over the rolling bearing back to the body of the lubricant reservoir within the absorbent extension.

Disclosure of Invention

The present invention provides a pump, comprising:

a pump housing;

a pumping mechanism disposed in the pump housing, the pumping mechanism comprising a rotor shaft having an axis of rotation;

a plurality of bearings supporting the rotor shaft for rotation relative to the pump housing, the plurality of bearings including a rolling bearing having an outer periphery, a first major side disposed in a first plane extending transverse to the rotational axis, and a second major side disposed in a second plane spaced apart from the first plane and extending transverse to the rotational axis;

a lubricant supply system; and

a lubricant transfer device provided on the rotor shaft to transfer lubricant from the lubricant supply system to the first main side of the rolling bearing,

wherein the lubricant supply system comprises a lubricant reservoir and a lubricant return system by which lubricant leaving the rolling bearing at the second main side is returned to the lubricant reservoir, and

wherein the lubricant return system comprises a lubricant return passage having an upstream end and extending from the upstream end over the outer periphery and through the first plane, and configured such that, in use, lubricant is movable in an upward direction in the lubricant return passage by capillary action.

The invention also includes a method of manufacturing a pump comprising: a pump housing; a pumping mechanism comprising a rotor shaft supported by a plurality of bearings, the plurality of bearings comprising rolling bearings; and a lubricant reservoir for supplying lubricant to lubricate the rolling bearing, the method comprising:

providing a seat for the rolling bearing; and

providing a lubricant return passage via which lubricant passing through the rolling bearing in use is returned to the lubricant reservoir,

wherein the lubricant return passage has an upstream end and extends over an outer periphery of the rolling bearing to the lubricant reservoir and is configured such that, in use, lubricant at the upstream end is movable in an upward direction by capillary action in the lubricant return passage, and

wherein at least a portion of the vacuum pump in which the lubricant passageway is defined is formed by a generative production process.

The invention also includes a pump comprising:

a pump housing;

a plurality of bearings supporting the rotor shaft for rotation relative to the pump housing, the plurality of bearings including a rolling bearing having an outer periphery, a first major side disposed in a first plane extending transverse to the rotational axis, and a second major side disposed in a second plane spaced from the first plane and extending transverse to the rotational axis;

a lubricant supply system; and

wherein the lubricant return system comprises a lubricant return passage (past) having an upstream end and extending from the upstream end beyond the outer periphery and through the first plane and configured such that, in use, lubricant is movable in the lubricant return passage in an upward direction by capillary action against gravity and in the absence of absorbent wicking material mounted in the lubricant return passage.

The invention also includes a pump comprising:

a pump housing;

a lubricant supply system; and

wherein the lubricant return system comprises a plurality of lubricant return passages and the passages have respective cross-sectional areas of different sizes, whereby in use, as these respective cross-sectional areas change due to thermal expansion and contraction due to changes in temperature conditions in the pump, the different lubricant return passages become operative to move the lubricant exiting the rolling bearing in an upward direction by capillary action.

The invention also includes a pump comprising:

a pump housing;

a lubricant supply system; and

wherein the lubricant supply system comprises a lubricant reservoir and a lubricant return system by which lubricant leaving the rolling bearing at the second main side is returned to the lubricant reservoir,

wherein the lubricant return system comprises a lubricant return passage having an upstream end and being configured such that, in use, lubricant is movable in an upward direction by capillary action in the lubricant return passage, and

wherein at least one of i) the pump housing or ii) a retainer mounted into the pump housing that retains the lubricant reservoir comprises a non-porous first portion and at least one second portion having a porous structure, and the at least one second portion defines at least a portion of the lubricant return passage.

Drawings

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

FIG. 1 is a schematic illustration of a turbomolecular pump in an inverted state;

FIG. 2 is a schematic illustration of a lubricant supply system for a rolling bearing of the turbomolecular pump of FIG. 1;

FIG. 3 is a cross-sectional view illustrating aspects of the lubrication supply system according to FIG. 2;

FIG. 4 is a cross-sectional view illustrating aspects of another lubrication supply system according to FIG. 2;

fig. 5 shows the internal structure of a lubricant return passage that can be used in the lubrication supply system.

Detailed Description

Referring to fig. 1, a turbomolecular pump 110 comprises a pump housing or casing 112, a pumping mechanism 114 disposed in the pump housing, an inlet 116, and an outlet 118. Pump housing 112 provides an enclosed space in which pumping mechanism 114 is housed and may include internal walls or partitions that divide the enclosed space into multiple compartments or provide mounting for pump components. Pump housing 112 may include multiple portions that are permanently or semi-permanently connected to one another. The pumping mechanism 114 may comprise a turbomolecular pumping mechanism comprising a plurality of rotor blades 120 disposed in a staggered relationship with a plurality of stator disks 122. The rotor blades 120 may be mounted on or integral with a rotor shaft 124 having a longitudinal axis (axis of rotation) 126. The rotor shaft 124 is driven by a motor 128 to rotate about an axis of rotation 126. The pumping mechanism 114 may additionally comprise a molecular drag pumping mechanism 130, which may be a Gaede mechanism, a Holweck 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 including a regenerative mechanism.

Still referring to FIG. 1, the rotor shaft 124 is supported by a plurality of

bearings

132, 134. The plurality of bearings may include two

bearings

132, 134 positioned at or adjacent to respective ends of the rotor shaft 124 as shown, although this is not necessary, and in other examples, one or both bearings may be disposed intermediate the ends of the rotor shaft. In yet a further example, the rotor shaft 124 may be supported by two bearings located near the base of the shaft, with the rotor blades 120 being cantilevered. In the example illustrated by fig. 1, 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, optionally, a backup rolling bearing (not shown) may be provided.

Referring to fig. 2, the rolling bearing 132 includes an outer periphery 136, a first major side 138 disposed in a first plane 140 extending transverse to the axis of rotation 126, and a second major side 142 disposed in a second plane 144 spaced apart from and extending transverse to the axis of rotation. The outer periphery 136 is disposed a first radial distance R1 from the axis of rotation 126. The first and

second planes

140, 144 may be perpendicular to the axis of rotation 126 and disposed in parallel spaced apart relation. The distance d between the first plane 140 and the second plane 144 may correspond to the height of the rolling bearing 132. As illustrated by the examples shown in fig. 3 and 4, a rolling bearing 132 is provided between the first end portion of the rotor shaft 124 and a bearing holder 145 mounted in the housing. The bearing holder 145 defines a seat 146 (fig. 4) for the rolling bearing 132. The seat 146 may be configured to engage and position the outer periphery 136 and the second major side 142 of the rolling bearing 132. In other examples, the seat for the rolling bearing 132 may be defined by a portion of the pump housing 112 rather than by a removable retainer.

Referring to fig. 1 and 2, with reference to a datum 147 extending transverse to the longitudinal axis 126 and bisecting the axis at a location intermediate the

bearings

132, 134, when the turbomolecular pump 110 is in an inverted state, the rolling bearing 132 rests above the datum 147. Although not necessary, in the illustrated example, the longitudinal axis 126 is disposed perpendicular to the reference plane 147, and the rolling bearing 132 is disposed toward the top of the turbomolecular pump 110 and the bearing 134 is disposed toward the bottom of the pump. In this orientation of the turbomolecular pump 110, the rolling bearing 132 may be referred to as an upper bearing, and the bearing 134 may be referred to as a lower bearing.

Still referring to fig. 1 and 2, a lubricant supply system 148 is provided to supply lubricant to a lubricant transfer device 150 via which lubricant from the lubricant supply system is transferred to the rolling bearing 132 to cool and lubricate the bearing. The lubricant supply system 148 may include a lubricant reservoir 152 and at least one contactor 154 via which lubricant from the lubricant reservoir is supplied to the lubricant transfer device 150. The lubricant supply system 148 may also include a lubricant return system 156 by which lubricant that has been supplied to the first main side 138 of the rolling bearing 132 by the lubricant transfer device 150 and exits via the second main side 142 is returned to the lubricant reservoir 152.

As best seen in fig. 3, the lubricant reservoir 152 may include two reservoir body portions 152-1, 152-2, and the one or more contactors 154 may take the form of one or more fingers that project inwardly from the lubricant reservoir to engage the lubricant transfer device 150. One or more contacts 154 may protrude from a body member 160 that is sandwiched between the first and second reservoir body portions 152-1 and 152-2. In use, lubricant from the lubricant reservoir 152 flows to the lubricant transfer device 150 via the one or more contactors 154, and lubricant that has passed through the rolling bearing 132 is returned to the lubricant reservoir via the lubricant return system 156. For simplicity, in the following description of fig. 1-3, reference will be made to only one contactor 154, but it will be understood that this will not be considered limiting as two, three or more contactors may be provided.

The lubricant return system 156 may include one or more lubricant return passageways 158 and lubricant collection channels (channeling) 168 configured to receive lubricant that has passed through the rolling bearing 132 and direct it in a lateral direction relative to the axis of rotation 126 to the one or more lubricant return passageways 158. For simplicity, in the following description of fig. 1-3, reference will be made to only one lubricant return passage 158, although it will be understood that this will not be considered limiting as there may be two or more lubricant return passages 158.

Referring to fig. 3, the lubricant collection channel 168 has a downstream end 170 and an upstream end 172. The lubricant collection channel 168 may be configured to direct lubricant that has passed through the rolling bearing 132 in a generally radially outward direction from a location adjacent the second major side 142 of the rolling bearing 132 toward the upstream end 174 of the lubricant return passageway 158. The upstream end 172 of the lubricant collection channel 168 may include an arcuate channel portion extending at least partially around the rotor shaft 124, and the downstream end 170 may be a free end of a bur-shaped channel portion extending outwardly from the arcuate channel portion. The arcuate channel portion may comprise an annular channel portion, and a bur-shaped channel portion may project radially outwardly from the annular channel portion. An upstream end 174 of the lubricant return passageway 158 may be disposed at or adjacent to a downstream end 170 of the lubricant collection channel 168 to receive lubricant from the lubricant collection channel 168 and return it to the lubricant reservoir 152. Although not necessary, the upstream end 174 of the lubricant return passageway 158 and the downstream end 170 of the lubricant collection channel 168 may be disposed a second radial distance R2 from the axis of rotation 126 that is greater than the first radial distance R1. The upstream end 174 of the lubricant return passageway 158 may be disposed in a third plane 176 (fig. 2) extending transverse to the axis of rotation 126 and spaced from the first and

second planes

140, 144. The third plane 176 may be disposed parallel to the first plane 140 and the second plane 144, and the second plane 144 may be disposed intermediate the first plane and the third plane. In some examples, the absorbent collector body 177 may be disposed in the collection channel 168.

Referring to fig. 2, the lubricant return passageway 158 may extend from the downstream end 170 of the lubricant collection channel 168 past the outer periphery 136 of the rolling bearing 132 and through the first and second

planar surfaces

140, 144 to a surface 178 of the lubricant reservoir 152 that is disposed closest to the rolling bearing 132. The lubricant return passage 158 may extend parallel to the rotational axis 126 of the rotor shaft 124. With respect to the axis of rotation 126, the lubricant return passage 158 may be disposed a radial distance from the axis of rotation 126 that is greater than the first radial distance R1 for at least the portion of its length that is disposed adjacent the outer periphery 136 of the rolling bearing 132. Thus, in some examples, while the portion of the lubricant return passageway 158 extending from the upstream end 174 through the first and

second planes

140, 144 is disposed radially outward from the outer periphery 136 of the rolling bearing 132 at, for example, a radius R2, the lubricant return passageway may converge on the rotor shaft 124 as it approaches the lubricant reservoir 152.

The lubricant return passageway 158 is configured such that, in use, lubricant from the lubricant collection channel 168 or, where provided, the absorbent collector body 177 is drawn into the upstream end 174 of the lubricant return passageway 158 and caused to move upwardly against gravity toward the lubricant reservoir 152 by capillary action. It will be appreciated that the lubricant return passageway 158 is relatively narrow to provide the desired proportion for capillary action to occur in the absence of an absorbent wicking material such as felt and is shown disproportionately in fig. 3 for purposes of illustration. It will also be appreciated that while only one lubricant passage 158 may be present in some examples, as mentioned above, multiple lubricant return passages may be present. This may be desirable to provide sufficient flow capacity to provide better distribution of the returned lubricant around the lubricant reservoir 152 by delivering the returned lubricant to separate spaced apart locations in the reservoir, or to provide a separate return route in the event that the passageway may become blocked. In examples where there are multiple lubricant return passages 158, the lubricant collection channel 168 may include an inner channel portion extending at least partially about the rotor shaft 124, and a respective connecting portion extending between the inner channel portion and a respective upstream end of the lubricant return passage.

The lubricant reservoir 152, at least one contact 154, body member 160, and absorbent collector body 177 (when provided) can be made of one or more stable fibrous materials capable of directing lubricant by capillary or wicking action. The fibrous material may be natural or synthetic, and in some examples, may be a felt material. The lubricant reservoir 152, the at least one contactor 154, the body member 160, and the collector body 177 (when provided) may be made of the same fibrous material, although different fibrous materials may be used in some examples. Although not necessary, one or both reservoir body portions 152-1, 152-2 of the lubricant reservoir may include a plurality of relatively thin layers of fibrous material stacked on top of each other, as shown in fig. 3 and 4.

Still referring to FIG. 3, the lubricant return system 156 may further include a deflector 179 mounted on the rotor shaft 124. Deflector 179 may include a drop former 180 to prevent lubricant from flowing along the bottom side of the deflector (as viewed in fig. 3) toward rotor shaft 124. As shown, the drop formation 180 may comprise a depending annular skirt, although it may take many other forms, such as an annular groove in the bottom side of the deflector. The deflector 179 may be mounted on the rotor shaft 124 such that the rolling bearing 132 is disposed between the deflector and the lubricant transfer device 150. The deflector 179 is positioned such that lubricant that has passed through the rolling bearing 132 can impinge on the deflector. The deflector 179 is configured to deflect lubricant that has passed through the rolling bearing 132 into the lubricant collection channel 168. The deflector 179 may seat on a shoulder defined by the reduced diameter section of the rotor shaft 124. The shoulder may be disposed adjacent to an aperture 186 disposed 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 pump housing 112 (integral part) or an element that fits into and is secured to the housing 112. The deflector 179 is configured to shield the aperture 186 from lubricant that has passed through the rolling bearing 132 entering and deflecting or diverting the lubricant into the lubricant collection channel 168. In the illustrated example, the deflector 179 is mounted on the rotor shaft 124. In some examples, the deflector may be provided on a rolling bearing, such as an inner ring.

Still referring to fig. 3, the lubricant supply system 148 may include

retainers

190, 194 to maintain the lubricant reservoir 152 and the body member 160 in an assembled state. The

retainers

190, 194 may include: a main retainer body 190 configured to receive the lubricant reservoir 152 and the body member 160; and an extension body 194 at least partially defining the lubricant return passageway 158. The extension body 194 may be integral with the main retainer body 190 (as shown in fig. 3), or may be a separate part that is secured to the main retainer body or mounted in the pump housing 112 such that it abuts the inner end of the main retainer body.

Bearing retainer 145 and

retainers

190, 194 may be received in a recess 200 provided at an end of pump housing 112. The inner end of the recess 200 may be at least partially defined by the divider 188. The

retainers

190, 194 may be held in place in the recess 200 by end caps 202, which may be secured to the housing 112 by bolts 204, clamps, screws, or any other suitable securing mechanism.

As shown in fig. 3, the lubricant transfer device 150 may include a hollow frustoconical body secured to the rotor shaft 124. The lubricant transfer device 150 has a longitudinal axis that coincides with the longitudinal axis 126 of the rotor shaft 124. The lubricant transfer device 150 has an outer surface 206 that tapers radially outward relative to the longitudinal axis 126 as the lubricant transfer device 150 approaches the rolling bearing 132. The rotor shaft 124 and the lubricant transfer device 150 may be provided with a male thread and a female thread, respectively, so that the lubricant transfer device can be screwed onto the rotor shaft in the manner of a nut. Alternatively, in some examples, the lubricant transfer device 150 may include a sleeve-like configuration that slides onto the rotor shaft 124 and is secured to the rotor shaft by means of nuts, bolts, screws, 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 be screwed into a female thread provided in an end of the rotor shaft.

Fig. 4 shows an alternative lubrication system for the turbomolecular pump 110. The same or similar components as those shown in fig. 3 will be referred to by the same reference numerals and may not be described again in detail. In the arrangement shown in fig. 3, there are no

retainers

190, 194 for the lubricant reservoir and body member 160. Instead, these are seated in recesses defined in the housing 112.

In this example, the lubricant return system 156 includes a plurality of lubricant return passages 158, and the lubricant collection channel 168 includes an optional lubricant return reservoir 169 disposed at a downstream end of the lubricant collection channel 168 adjacent a respective upstream end 174 of the lubricant return passages 158. Thus, in use of this example, lubricant that has passed through the rolling bearing 132 and exited at the second major side 142 is directed to the lubricant return reservoir 169 where it is drawn into one or more of the lubricant return passageways 158 and moves upward by capillary action toward the lubricant reservoir 152.

In some examples, the lubricant return passages 158 may have respective cross-sectional areas that are different in size such that, in use, as these respective cross-sectional areas change due to thermal expansion and contraction (caused by varying temperature conditions in the turbomolecular pump 110), the different lubricant return passages become operative to move lubricant in an upward direction by capillary action. Thus, when one or more lubricant return passages 158 become inoperative due to expansion or contraction (caused by varying thermal conditions in the turbomolecular pump 110), at least one of the lubricant return passages 158 will become or remain operative to direct lubricant upward by capillary action. Although not limited to lubricant passages having a right circular (circular) cross-section, in examples where the lubricant return passage has a circular cross-section, the corresponding differently sized cross-sectional areas would be the product of the different passage diameters. It will be appreciated that in examples where there are a plurality of differently sized lubricant return passages, it is not necessary that all of the lubricant return passages be of different sizes. For example, in an example with eight lubricant return passages, two may have a cross-sectional area dimension a, two may have a cross-sectional area dimension B, two may have a cross-sectional area dimension C, and two may have a cross-sectional area dimension D, where a > B > C > D.

In at least some examples, the pump housing 112, or at least a portion of the pump housing in which the or one (the or a) lubricant passage is defined, may be manufactured with one or more integral lubricant return passages by a generative production process, referred to as 3D printing or Additive Manufacturing (AM). Suitable generative production processes may include material extrusion, including Fuse Deposition Modeling (FDM), binder jetting, powder bed fusion, directed energy deposition, and sheet lamination. Of these, powder bed fusion or fuse deposition modeling may be particularly suitable, where the casing is built to leave open one or more passageways through which returned lubricant may flow or sintered powder is removed to form one or more lubricant return passageways. For example, fuse deposition molding may use a suitable metal to form the pump housing and epoxy to define one or more lubricant return paths such that when the structure is heated to fuse the metal powder, the epoxy is melted. An advantage of this method is that it is not necessary to remove metal powder to clear one or more of the vias. Similarly, in examples where the or a (the or a) lubricant return passage is provided in a retainer mounted in pump housing 112, the retainer may be formed by a generative manufacturing process.

It will be understood that the lubricant collection channel may also be formed in a part of the manufacture by means of a generative production process (e.g. a part of the pump housing) together with the lubricant return passage. It will also be appreciated that the lubricant collection channel may comprise a hole or passage extending within the portion in which the lubricant collection channel is defined, and that it is not limited to an open channel.

With reference to fig. 5, it is not essential that the or each lubricant return passage is an open passage; as long as the passageway includes an uninterrupted open or empty flow path. The lubricant return path may be defined at least in part by a portion of the pump housing 112 that, although not structurally lacking, has a greater porosity than surrounding portions of the pump housing that is sufficient to allow lubricant to flow therethrough. Thus, as shown in fig. 5, pump housing 112 may include a first portion 210 that is a substantially non-porous structure capable of providing the gas impermeability and strength necessary to perform its housing and load supporting functions, and a second portion 212 having a relatively greater porosity, thereby providing a relatively more open structure that defines a plurality of micro-passageways that, in combination, define a lubricant return passageway. Thus, the lubricant return passageway may be defined by a region of relatively higher porosity surrounded by a substantially non-porous structure. Configuring the lubricant return passage as a porous region within a substantially non-porous structure may provide improved heat transfer compared to open channels. As shown in fig. 5, the higher porosity second portion 212 defining the lubricant return passage may be defined by a regular mesh or honeycomb structure, an amorphous structure, or a combination of both.

Still referring to fig. 5, while in some examples the or one (the or a) lubricant return passageway may comprise an open tubular structure sized to provide a capillary effect, the or one (the or a) lubricant return passageway may instead comprise an outer portion defined by a groove 214 extending in a lengthwise direction of the lubricant passageway, and an at least substantially uninterrupted passageway disposed inwardly from the groove 214. The capillary effect may then be provided by a grooved or porous portion of the lubricant return passageway.

Although not limited to these materials, the pump housing may be made of aluminum, aluminum alloy, or stainless steel.

It will be appreciated that providing one or more lubricant return passages as disclosed herein allows for the possibility of using the pump in any desired orientation (including the fully inverted orientation as shown in fig. 1), while allowing for reliable return of lubricant from the rolling bearing to the lubricant reservoir for re-supply to the bearing. In contrast to systems in which lubricant return is achieved by wicking achieved using a rod made of absorbent material, significant space savings can be achieved by having one or more lubricant return passages configured such that, in use, lubricant can move in an upward direction by capillary action against gravity, thereby eliminating the need for the absorbent material to be present to provide wicking. This is an advantage because space economy within the pump housing is often important, assembly problems associated with ensuring good contact of the absorbent rod with the lubricant reservoir are avoided, and there is less fibrous material in the pump which can cause loose fibres which contaminate the lubrication system. There may also be an advantage in terms of layout because the lubricant return path configured to move the lubricant upward by capillary force is not limited to extending in a straight line.

It will be appreciated that in the illustrated embodiment, the lubricant supply system is configured to supply lubricant from the lubricant reservoir to the rolling bearing, and to return the supplied lubricant that has passed downwardly through the rolling bearing to the lubricant reservoir via a lubricant return passage that extends upwardly across the rolling bearing. The lubricant return passage is configured such that the lubricant is able to move upward by capillary action against gravity in the absence of an absorbent wicking material or any other separate, non-integral structure in the lubricant return passage to provide capillary action. The lubricant return passage may be configured such that lubricant can be moved upward by capillary action against gravity by one or more of the following: the passage is suitably sized, a groove is formed in the wall defining the passage, or the passage is formed as a unitary porous structure within a non-porous body. Since it is not necessary to provide a separate absorbent wicking material in the lubricant return passage and configure the lubricant return passage such that capillary action is provided by the integral feature of the passage, it is possible to use a relatively narrower passage to achieve a more compact structure, avoid assembly tasks, avoid the use of fibrous material in the lubricant passage, which can shed fibers into the lubricant circulation path.

In the illustrated example, the lubricant return system includes a lubricant collection channel in which lubricant that has passed through the rolling bearing is received and directed to a location radially outward from the outer periphery of the rolling bearing. This is not essential. For example, the lubricant collection channels may be located completely inward from the outer periphery of the rolling bearing, and the one or more lubricant return passages may have an upstream end portion connected to such channels and configured to deliver lubricant generally radially outward relative to the rolling bearing prior to turning in the general direction of the lubricant reservoir.

The one or more lubricant return passages may include two or more generally straight portions joined by a curved portion. The one or more lubricant return passages may include an arcuate portion, and in some examples, may include an arcuate portion and a straight portion or a combination of an arcuate portion, a curved portion, and a straight portion, as may be desired for deployment purposes.

In the illustrated example, the lubricant return passageway is planar along its direction of travel toward the lubricant reservoir. Thus, in the examples shown in fig. 3 and 4, although the lubricant return passages may extend parallel to, or at least partially converge on, the rotational axis of the rotor shaft, they are disposed in a single vertical (as viewed in fig. 3 and 4) plane containing the rotational axis of the rotor shaft. It will be appreciated that this is not essential. The lubricant return system may include one or more lubricant return passages that are at least partially non-planar along their direction of travel toward the lubricant reservoir. Thus, at least a portion of the lubricant return passages may be spaced from and wound relative to the axis of rotation of the rotor shaft such that, for example, one or more of the lubricant return passages may include a helical, spiral (spiraling) or otherwise arcuate portion extending through several planes that are vertical (as viewed in fig. 3 and 4) and contain the axis of rotation.

It will be appreciated that in examples in which the rotor shaft is supported by two bearings disposed adjacent to each other such that the rotor blades are cantilevered, each bearing may be a rolling bearing lubricated in a similar manner to the rolling bearing shown in fig. 3 and 4, wherein the lubricant return system to collect lubricant that has passed through the rolling bearing comprises a lubricant return passage to return collected lubricant to the one or more lubricant reservoirs by capillary action.

The lubricant may comprise any lubricant suitable for lubricating the bearing under conditions where the lubricant may comprise an organic or synthetic oil in the pump and sufficiently liquid applied to allow it to return to the lubricant reservoir via a lubricant return passage by capillary action.

It will be appreciated that although the lubricant return system shown in the drawings is described primarily in connection with a turbomolecular pump, the lubricant return system or a lubricant return system employing the same or similar capillary passages may be applied to the returned lubricant in other forms of pumps (e.g., a screw pump or a scroll pump) for re-supply.

Claims

1. A pump, characterized in that the pump comprises:

a pump housing;

a lubricant supply system; and

2. The pump of claim 1, wherein the lubricant return passageway extends alongside and is spaced apart from the axis of rotation so as to be disposed radially outward from the outer periphery at least when passing therethrough.

3. The pump of claim 1 or 2, wherein the outer periphery is disposed a first radial distance from the axis of rotation, the upstream end is disposed a second radial distance from the axis of rotation, and the second radial distance is greater than the first radial distance.

4. A pump according to claim 1 or 2, wherein the lubricant return passageway has a downstream end portion that discharges into the lubricant reservoir.

5. The pump of claim 4, wherein the downstream end is covered by the lubricant reservoir.

6. The pump of claim 1, wherein the upstream end of the lubricant return passageway is disposed in a third plane extending transverse to the axis of rotation, and the second plane is disposed intermediate the first and third planes.

7. The pump of claim 1, wherein the lubricant return system includes a lubricant collection channel configured to receive the lubricant exiting the rolling bearing at the second major side, and the upstream end of the lubricant return passage is connected with the lubricant collection channel to receive lubricant therefrom.

8. The pump of claim 1, wherein the lubricant reservoir has a surface disposed closest to the rolling bearing, and the first and second planes are disposed intermediate the surface and the upstream end of the lubricant return passageway.

9. The pump of claim 1, wherein the lubricant return passage is defined by:

i) the pump housing; or

ii) a retainer that retains at least one of the lubricant reservoir and the rolling bearing and is mounted in the pump housing.

10. The pump of claim 9, wherein the pump housing or the retainer comprises a non-porous first portion and at least one second portion having a porous structure, the at least one second portion defining at least a portion of the lubricant return passage.

11. The pump of claim 1, wherein the lubricant return passage is configured such that, in use, lubricant can move in an upward direction in the lubricant return passage by capillary action by at least one of:

i) has a relatively narrow cross-section; and

ii) has a groove extending along the lubricant passageway, the groove being disposed in the wall so as to define the lubricant return passageway.

12. The pump of claim 1, wherein the lubricant return passageway is disposed in a single plane containing the axis of rotation in a direction of travel from the upstream end toward the lubricant reservoir.

13. The pump of claim 1, wherein at least a portion of the lubricant return passageway is spaced from and intertwined with the rotational axis.

14. A pump according to claim 1, wherein the lubricant return system comprises a plurality of the lubricant return passages, and the passages have respective cross-sectional areas of different sizes, whereby in use, as the respective cross-sectional areas change due to thermal expansion and contraction due to changes in temperature conditions in the pump, different ones of the lubricant return passages become operative to move the lubricant in the upward direction by capillary action.