GB2602808A

GB2602808A - A thrust bearing and a method for reducing wear in a thrust bearing

Info

Publication number: GB2602808A
Application number: GB2100465.0A
Authority: GB
Inventors: Hofstad Åge; Smedsrud Lars; NÆrland Magnus
Original assignee: Aker Solutions AS
Current assignee: Aker Solutions AS
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2022-07-20
Anticipated expiration: 2041-01-14
Also published as: GB202100465D0; GB2602808B; WO2022154673A1

Abstract

A thrust bearing comprising a bearing pad 30a, 30b and a bearing housing 32. The bearing housing 32 comprising a pad engagement surface 50, and a retainer arrangement 46. The bearing pad comprises a bearing surface 34 for receiving a load from a thrust disc 56, an oppositely disposed engagement surface 36, and a shoulder arrangement 38 for engaging the retainer arrangement 46. The bearing surface 36 is oriented at a non-zero angle relative to the surface of the thrust disc 56. The disclosure further relates to a method for reducing wear in a thrust bearing using a lubricant.

Description

A thrust bearing and a method for reducing wear in a thrust bearing

Technical field

The present disclosure relates to a thrust bearing and a method for reducing wear in a thrust bearing. More specifically, the disclosure relates to a thrust bearing and a method for reducing wear in a thrust bearing as defined in the introductory parts of claim 1 and claim 16.

Background art

Bearings are an important component of pumps and compressors, as they assist to allow rotating components of pumps and compressors to rotate without excessive friction, thereby preventing damage and wear being caused unnecessarily. The design of bearings is important, as having well-designed bearings can greatly increase the lifespan of the component into which they are installed, particularly if the bearings are well maintained.

One bearing that is common in pumps and compressors is a thrust bearing. A thrust bearing is used to control thrust forces that are generated by the rotor of a pump or compressor, directed parallel to the rotational axis of the rotor. Often, a thrust bearing interacts with a thrust disc, which is disposed on the rotor. Axially offset from, and adjacent to, the thrust disc is located the thrust bearing. In some cases, a single thrust bearing may be located adjacent the thrust disc (e.g. there may be a thrust bearing located on a single axial side of the thrust disc), while in other cases two thrust bearings may be present, and may be located on each axial side of the thrust bearing -such a configuration may be considered to be a double-acting thrust bearing arrangement. As thrust forces are generated, the thrust disc is forced against the thrust bearing, which provides an opposing force in order to prevent excessive axial movement of the rotor which would result in damage to the pump.

In some instances, for example where the rotor is vertically oriented, a thrust bearing located towards the lower end of the rotor will experience the more of the thrust forces produced by the rotor than bearings located towards the top of the rotor. In some cases, for example where there is a double-acting thrust bearing arrangement, the upper thrust bearing located towards the top of the rotor may receive negligible loading. However, despite the lack of loading from the rotor, such bearings have been shown to still experience wear, sometimes at unacceptably high rates. It is thought that, without any loading from the rotor, the pads in the thrust bearing are not able to position themselves correctly with respect to the thrust disc.

This may lead to bearing pads contacting and lying flat on the thrust disc. Then, as the thrust disc rotates with the rotor, this contact prevents or restricts a flow of lubrication fluid between the bearing pad and the thrust disc, leading to overheating and excessive wear on the bearing pads. This problem is particularly acute in cases where the lubricating fluid is water-based.

Existing solutions to this problem involve spring-loading bearing pads in the thrust bearing to artificially create a loading on the bearing. However, in these solutions the entire functionality of the bearing becomes reliant on a loaded spring mechanism, which may have the effect of decreasing the lifespan of the bearing.

Summary

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above-mentioned problem. According to a first aspect there is provided a thrust bearing, comprising: a bearing pad comprising a bearing surface for receiving a load from a thrust disc, and an oppositely disposed engagement surface for engaging a bearing housing; a bearing housing comprising a pad engagement surface, and a retainer arrangement disposed on the bearing housing; the bearing pad comprising a shoulder arrangement for engaging the retainer arrangement, the shoulder arrangement being located between the bearing surface and the engagement surface; wherein at least one of: a first portion of the shoulder arrangement is located closer to the bearing surface than a second portion of the shoulder arrangement; and a first portion of the retainer arrangement is located closer to the pad engagement surface than a second portion of the lip arrangement; such that the bearing surface is oriented at a non-zero angle relative to the thrust disc.

In use, the thrust bearing may be positioned in pump or compressor, axially adjacent to a thrust disc, and may permit the turning of a drive shaft that experiences axially directed thrust forces. As the drive shaft rotates, the thrust bearing is positioned at a non-zero angle relative to the thrust disc of the drive shaft, thereby permitting a supply of lubrication fluid to be provided between the thrust disc and the thrust bearing, greatly reducing the wear upon the thrust bearing and increasing its useable lifespan, without the requirement for external intervention, and no matter the orientation of the thrust bearing.

According to a second example of the first aspect, the retainer arrangement comprises a single retainer profile extending in a ring configuration. The single lip may extend in a ring around the periphery of the bearing pad, or around the periphery of a cavity for the bearing pad.

According to a third example, the retainer arrangement comprises at least two retainer profiles, each extending around a section of the periphery of the bearing pad. The at least two lips together may extend in a ring, or part of a ring, configuration.

According to a fourth example, the retainer arrangement extends in a non-parallel direction to the engagement surface.

According to a fifth example, the retainer arrangement comprises at least one retainer profile, the at least one retainer profile extending in a non-parallel direction to the engagement surface.

The retainer arrangement may assist to secure the bearing pad in place, while permitting movement of the bearing pad within the cavity.

According to a sixth example, a first of the at least two retainer profiles is located closer to the pad engagement surface than a second of the at least two retainer profiles.

An arrangement where one lip is located closer to the pad engagement surface than another may assist to hold the bearing surface at a non-zero angle relative to the surface of the thrust disc, while permitting movement of the thrust disc within the cavity, thereby allowing the thrust disc to reorientate based on the present pressure profile in the lubrication fluid.

According to a seventh example, the shoulder arrangement comprises a single shoulder extending around the periphery of the bearing pad.

According to an eighth example, the shoulder arrangement comprises at least two shoulders, each of the at least two shoulders extending around a section of the periphery of the bearing pad.

Having a shoulder arrangement may permit simple engagement with the lip arrangement while allowing movement of the bearing pad relative to the bearing housing, while holding the bearing pad securely relative to the bearing housing.

According to a ninth example, the bearing housing comprises a cavity for receiving at least a part of the bearing pad therein.

According to a tenth example, the cavity is defined by the bearing housing and the retainer arrangement.

In such examples, it may be possible to vary the angle relative to the surface of the thrust disc using the lip arrangement alone, and reconfiguration of the lip arrangement may suffice to change the angle between the bearing surface and the surface of the thrust disc (e.g. by replacing the lip arrangement, or repositioning the lip arrangement).

According to an eleventh example, the bearing surface is oriented at an angle of between 0 and 30 degrees relative to the thrust disc.

According to a twelfth example, the bearing surface is oriented at an angle of between 3 and 8 degrees relative to the thrust disc.

Having a specific offset angle may assist to provide a maximum flow of lubrication fluid between the thrust disc and the bearing pad, and may therefore optimally reduce wear on the thrust disc.

According to a thirteenth example, the thrust disc and the bearing surface are axially separated so as to prevent direct engagement between the bearing surface and the surface of the thrust disc.

Having an axial separation may assist to permit lubrication fluid between the bearing surface and the surface of the thrust disc, even in situations where there is no movement therebetween, or where there is no loading from the thrust disc onto the thrust bearing.

According to a fourteenth example, the thrust disc comprises a plurality of bearing pads, each bearing pad located in a separate bearing housing.

Having a plurality of bearing pads in separate housings may prevent interaction between the bearing pads, thereby reducing unwanted contact, and unwanted wear on the bearing pads.

S

According to a fifteenth example, the separate bearing housings are located in a radial or circular array formation.

According to a sixteenth example, the thrust disc comprises a protrusion on the pad engagement surface for engaging the engagement surface, and permitting pivoting of the bearing pad on the protrusion.

According to a seventeenth example, the shoulder arrangement comprises a first shoulder and a second oppositely oriented shoulder, so as to create a slot in the bearing pad located between the first and the second shoulders. The slot may be defined by the first and second shoulders.

Having a slot in the bearing pad may assist to secure the bearing pad in the housing, and increase the ease of which the angle of the bearing pad relative to the surface of the thrust bearing may be controlled or changed.

According to an eighteenth example, the thrust bearing comprises a washer plate coupled to the housing and configurable to engage with the slot in the bearing pad.

Having a washer plate may provide the skilled user with the option of varying the angle of the washer plate, and thereby the angle at which the bearing pad is held relative to the thrust disc.

According to a second aspect there is provided a method for reducing wear in a thrust bearing, comprising: providing a bearing pad comprising a bearing surface in a bearing housing; providing a thrust disc for exerting a load on the bearing pad; orienting the bearing pad relative to the housing such that the bearing surface is located at a non-zero angle relative to the thrust disc when the thrust disc is stationary relative to the bearing pad; rotating the thrust disc relative to the bearing pad, so as to generate a pressure profile in a lubricant fluid.

According to a second example of the second aspect, the method comprises axially separating the thrust disc and the bearing pad to provide a gap and prevent direct contact therebetween.

According to a third example of the second aspect, the method comprises creating a pressure profile in a lubricant fluid located in the gap.

Effects and features of the second aspect are to a large extent analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect.

The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the

disclosure.

Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

Brief descriptions of the drawings

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Figure 1 shows a cross-sectional view of a pump.

Figures 2A-C illustrate a schematic illustration of part of an example thrust bearing. Figures 3A-B illustrate a schematic illustration of a second example of a thrust bearing. Detailed description The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Figure 1 is an illustration of a pump 10, having drive-end and non-drive-end thrust bearings 20a, 20b located therein. As their names would suggest, the drive-end and non-driveend bearings 20a, 20b, are located towards the drive-end and non-drive-end, respectively, of a drive shaft 12 of the pump 10. Between the drive-end and non-drive-end bearings 20a, 20b is located a thrust disc 24, which in this example is integrally formed with a drive shaft 12 of a rotor, although may be attached to the rotor in any appropriate way. In some examples, further thrust bearings may be present, which may be located intermediate the drive-end and non-drive end thrust bearings 20a, 20b. In some examples, the drive-end bearing 20a may be located on the drive shaft 12 adjacent the thrust disc 24 and located closer to the drive-end of the drive shaft 12, while the non-drive-end bearing 20b may be located on the shaft adjacent the thrust disc 24 and located closer to the non-drive-end of the drive shaft 12. The reader will appreciate that while, in this example, the pump 10 is shown with the drive shaft 12 being horizontally oriented, the pump 10 may be used in an alternative orientation by the user, in which the drive shaft 12 is vertically oriented. In a vertical orientation, one of the drive-end thrust bearing 20a and the non-drive end thrust bearing 20b will be positioned so as to be located towards the top of the drive shaft 12, and may be an "upper" thrust bearing, while the other will be positioned so as to be located towards the bottom of the drive shaft 12, and may be a "lower" thrust bearing, which may vary depending on the chosen orientation of the pump 10.

Coupled to the shaft 12 are a plurality of impellers 14, the rotation of which may cause a thrust force directed in the direction of the axis of rotation of the shaft 12, and together the impellers 14 and the drive shaft 12 are comprised in the rotor of the pump. A motor compartment 16 is illustrated towards the drive-end of the drive shaft 12, which is attached to the drive shaft 12 so as to permit rotation of the drive shaft 12 in operation. The rotor is supported in a housing 18, which additionally defines fluid ports 22a, 22b that allow a fluid to flow into and out of the pump 10.

The thrust disc 24 is positioned axially adjacent the drive-end and non-drive-end thrust bearings 20a, 20b, such that the thrust disc 24 is able to bear against either thrust bearing 20a, 20b in the event of thrust forces being produced by the rotating drive shaft 12, in either axial direction. In this example, the thrust disc is concentric with the axis of the drive shaft 12, and the bearing surfaces (the surface that is configurable to come into contact with the thrust bearing) extend perpendicular to the axis of the drive shaft. Here, the bearing surfaces are flat.

Figures 2A and 2B illustrate part of a thrust bearing, such as that described in relation to Figure 1. Here, part of a thrust bearing 10 is illustrated in a sectional view. Shown are two bearing pads 30a, 30b of the thrust bearing 10. In this example, the bearing pads 30a, 30b are positioned relative to a bearing housing 32, and in this example are partially positioned in the bearing housing 32. Each of the bearing pads 30a, 30b comprises a bearing surface 34 and an oppositely disposed engagement surface 36. As is illustrated, the bearing surface 34 is located so as to face a surface 40, which is the surface of a thrust disc in this example. The angle may be any angle greater than 0 degrees, for example any angle greater than 0 degrees, to 30 degrees, or in some examples the angle may include 0 degrees. In some examples, it may be preferable to have an angle of between 3 and 8 degrees. Having the bearing pad 30a, 30b located at an angle a (illustrated in Figure 2A) relative to the surface 40 may permit an increased volume of lubrication fluid to pass between the bearing pad 30a, 30b and the surface 40, which may improve the lubrication of the thrust bearing 10 and reduce the wear thereon, thereby prolonging its useable lifespan.

Each bearing pad 30a, 30b comprises a shoulder arrangement 38, which is disposed intermediate (e.g. axially intermediate) the bearing surface 34 and the engagement surface 36. As is illustrated in Figures 2A and 2B, the shoulder arrangement 38 protrudes in a lateral direction from the bearing pad 30a, 30b, and permits the bearing pad 30a, 30b to engage with the housing 32 (or, as will be described in the following paragraphs, a retainer arrangement 46 which may form part of the housing 32). In the cross-sectional illustration of Figures 2A and 2B, the shoulder arrangement 38 protrudes laterally from both sides of the bearing pad 30a, 30b. In some examples, the shoulder arrangement 38 may comprise a single shoulder that extends fully around the periphery of the bearing pad 30a, 30b, while in other examples, the shoulder arrangement 38 may comprise multiple individual shoulders (e.g. two individual shoulders) that each extend around at least a section of the periphery of the bearing pad 30a, 30b. Together, the multiple individual shoulders may surround the entire periphery of the bearing pad 30a, 30b, or in other examples, there may be sections of the periphery each bearing pad 30a, 30b that do not comprise any shoulder. As illustrated, in this example one portion of the shoulder arrangement 38 is located closer to the bearing surface 34 than another portion of the shoulder arrangement 38. The portion of the shoulder arrangement 38 that is located closer to the bearing surface 34 may be part of the same shoulder as the portion of the shoulder arrangement 38 that is located further from the bearing surface 34. Alternatively, the portion of the shoulder arrangement 38 that is located closer to the bearing surface 34 may be, or be part of, a separate shoulder than the portion of the shoulder arrangement 38 that is located further from the bearing surface 38, in which case the shoulder arrangement 38 would comprise at least two shoulders. The portion of the shoulder arrangement 38 that is located further from the bearing surface 34 may be oppositely disposed on the bearing pad 30a, 30b compared to the portion of the shoulder arrangement 38 that is located closer to the bearing surface 34 (e.g. oppositely disposed on the periphery of the bearing pad 30a, 30b).

As previously indicated, the shoulder arrangement 38 may permit the bearing pad 30a, 30b to engage with the housing 32. Having a shoulder arrangement 38 that has one portion located closer to the bearing surface 34 than another portion of the shoulder arrangement 38 may permit the bearing pad 30a, 30b to be disposed in the housing such that the bearing surface 34 is inclined relative to the surface 40 of a thrust disc, while additionally providing a secure engagement between the housing 32 and the bearing pad 30a, 30b.

As illustrated and described previously, the bearing pads 30a, 30b are partially positioned in the bearing housing 32. In order to accommodate the bearing pads 30a, 30b, the housing comprises a cavity 42 in this example. The cavity 42 comprises an opening 44, which may be shaped to match the shape of the bearing pad 30a, 30b. The housing also comprises a retainer arrangement 46, which in this example is integrally formed with the housing and together with the housing 32 defines the cavity 42, although which may be attached to the housing by any appropriate means such as welding, chemical bonding, bolting, fastening, or the like. The retainer arrangement 46 may be in the form of a retainer plate, and/or may comprise a lip for engagement with the bearing pads 30a, 30b. Here, the retainer arrangement 46 defines one side of the cavity 42. Here, the retainer arrangement 46 is located in the cavity, and may be considered to partially define a boundary of the cavity 42, and defines the opening 44. The retainer arrangement 46 may extend around the periphery of the opening 44, for example around the entire periphery of the opening 44, or may extend intermittently around the periphery of the opening 44. It should be understood that alternative locations for the retainer arrangement 46 may be possible. For example, the retainer arrangement 46 may be located inside the cavity 42, such that there is an offset between the retainer arrangement 46 and the opening 44. Alternatively, the retainer arrangement 46 may be located on the housing outside of the cavity 42, for example the retainer arrangement 46 may extend laterally from the housing such that the retainer arrangement 46 is situated outside and adjacent to the cavity 42.

The retainer arrangement 46 may comprise a single retaining profile (which may be in the form of a lip or protruding edge or ridge, for example), or may comprise a plurality of retainer profiles, located around the periphery of the opening 44 in the housing 32 and extending in a ring configuration. Where the retainer arrangement 46 comprises a plurality of retaining profiles, the plurality of retaining profiles may together extend around the entire periphery of the opening 44, or there may be parts of the opening 44 in which there is no retaining profile present. For example, the retainer arrangement 46 may extend only partially around the periphery of the opening 44 in order to permit the bearing pad 30a, 30b to be more easily positioned in the cavity 42.

In some examples the retainer arrangement 46, or part thereof, may be removable from the housing 32. Such a feature may assist the user to replace or remove a bearing pad 30a, 30b where necessary, by permitting removal of the retainer arrangement 46 thereby facilitating access to the housing 32, and to the cavity 42 where a cavity 42 is present. In some examples, the housing 32 may be formed of a plurality of parts that are connected together. The retainer arrangement 46 may be located on or defined by a part of the housing 32 that is separable, thereby allowing the retainer arrangement 46 to be removed if desired.

As is visible from Figure 2A and Figure 2B, the shoulder arrangement 38 engages the retainer arrangement 46 such that the bearing pad 30a, 30b is held partially inside the cavity 42. As such, the part of the bearing pad 30a, 30b that is located between the shoulder 38 and the engagement surface 36 is located inside the cavity 42, while the part of the bearing pad 30a, 30b that is located between the shoulder arrangement 38 and the bearing surface 34 may be located outside the cavity 44. The reader will understand that, due to the engagement between the shoulder arrangement 38 the retainer arrangement 46, the location of the retainer arrangement 46 relative to the cavity 42 will have an effect on the positioning of the bearing pad 30a, 30b relative to the cavity 42. In examples where the retainer arrangement 46 is located outside of the cavity 42, then a different (e.g. smaller) volume of the bearing pad 38 may be located inside the cavity 42, while in examples where the retainer arrangement 46 is offset from the opening 44 and located inside the cavity 42, then a different (e.g. larger) volume of the bearing pad 38 may be located inside the cavity 42.

Inside the cavity 42 is located a pad engagement surface 50. In use, the pad engagement surface 50 may be configurable to permit abutment of the engagement surface 36 of the bearing pad 30a, 30b and the housing 32, so as to limit movement of the bearing pad 30a, 30b. In the orientation of this example, the pad engagement surface 50 may be considered to limit vertical movement of the bearing pad 30a, 30b, although the reader will understand that the thrust bearing 10 may have other configurations in which relative movement of the bearing pad 30a, 30b would be limited in a differing direction.

Located on the pad engagement surface 50 is a protrusion 52. The protrusion 52 is located on the pad engagement surface SO such that vertical movement of the bearing pad 30a, 30b in the cavity results in contact between the protrusion 52 and the bearing pad 30a, 30b in a non-central location (e.g. a location that is not central to an axis of the bearing pad 30a, 30b), although in some other examples, the protrusion may have a central location on the pad engagement surface 50. As such, the protrusion 52, when in contact with the bearing pad 30a, 30b, urges the bearing pad 30a, 30b to move in a pivotal direction about the protrusion 52. The protrusion may be considered to function in a similar way to a fulcrum, urging the bearing pad 30a, 30b to pivot when it comes into contact therewith. The pivoting of the bearing pad 30a, 30b in the cavity 42 may have the effect of increasing the angle between the bearing surface 34 and the surface 40 of a thrust disc. In turn, this may increase the propensity of a lubrication fluid to flow between the bearing pad 30a, 30b and the thrust disc, which may further protect the thrust bearing 10 from wear as a result of rotation of the thrust disc. Thus, as an increased thrust force is applied to the thrust bearing 10, causing the bearing pads 30a, 30b to abut against the protrusion 52 and permitting further or increased lubrication of the thrust bearing 10.

The protrusion 52 is illustrated, in this example, as a rectangular cross-sectioned rib that protrudes from the pad engagement surface 50 inside the cavity 42. However, in other examples other shapes of protrusion may be possible, for example a rib having a triangular or semi-circular cross-sectional shape, or a protrusion having a single point of contact with the engagement surface 36 such as a needle tip or a dome or semi-spherical head. Changing the shape of the protrusion 52 may alter the behavior of the bearing pad 30a, 30b by making the bearing pad able to move or rotate more or less easily in the housing 32.

In this example, the bearing housing 32 is formed of two parts 32a, 32b, which may make easier the manufacturing process of the thrust bearing 10. A first part of the bearing housing 32a provides a largely flat surface, which defines the pad engagement surface 50, and may additionally define the protrusion 52, or may provide an attachment surface for the protrusion 52 in examples where the protrusion 52 is not integrally formed with the bearing housing 32. The first part 32a may additionally provide a plurality of bores, which may be blind bores, therein, in order to facilitate the attachment of a second part of the bearing housing 32b thereto. The second part of the bearing housing 32b, in this example, defines the cavity 42, the opening 44 and may additionally define the retainer arrangement 46. As illustrated in Figures 2A and 2B, the second part 32b may provide a profile having a T-shaped cross-section of material between each cavity 42 (the T-shaped cross section being formed by a bolt in a sleeve, connecting the first part of the housing 32a to the second part 32b), thereby defining a cavity 42 within the housing 32 between the housing parts 32a, 32b, to hold a bearing pad or multiple bearing pads 30a, 30b therein. In some examples first and second part of the housing 32a, 32b may fit together to define separate cavities, thereby permitting the housing 32 to comprise multiple cavities therein 42.Although two bearing pads 30a, 30b are illustrated in this example, the thrust bearing 10 may comprise more than two bearing pads 30a, 30b, for example six bearing pads, or eight bearing pads.

Here, the second part 32b is attached to the first part 32a by means of a screw or bolt arrangement 54. In alternative examples, the first part 32a may be attached to the second part by any appropriate means, such as welding, chemical bonding, snap-fitting or the like. In some other examples, the first part 32a and the second part 32b may be integrally formed.

Figure 2A illustrates the thrust bearing 10 in a stationary state. In this stationary state, there is no movement of a thrust disc 56 positioned adjacent the thrust bearing 10, and a such there is very little, or no, flow of lubrication fluid past the thrust bearing 10. As such, the shoulder arrangement 38 is in engagement with the retainer arrangement 46. It should be noted that the engagement of the shoulder arrangement 38 with the retainer arrangement 46 prevents contact between the bearing surface 34 of the bearing pads 30a, 30b and the thrust disc 56. As such, a gap 58 is always maintained between the bearing pads 30a, 30b and the thrust disc 56, which may serve as a channel through which a lubrication fluid may flow, for example when the thrust disc 56 first starts rotating. As such, a lubrication fluid is always able to flow between the thrust disc and the bearing pads 30a, 30b and the problem whereby the bearing surface 34 of the lies (e.g. lies flat) on the thrust disc 56, thereby blocking, restricting or preventing flow of lubrication fluid is avoided.

In Figure 2B, there is illustrated the thrust bearing 10 and a thrust disc 56, where the thrust disc 56 is moving in the direction of arrow 60. In operation, the thrust disc 56 moves in a rotational direction about a drive shaft, as described in relation to Figure 1. As Figures 2A and 2B show a cross-sectional view of the thrust disc 56 and thrust bearing 10, arrow 60 is straight, although illustrates this rotational movement.

As the thrust disc 56 moves relative to the thrust bearing 10, the lubrication fluid begins to flow in the gap 58, and the pressure of the lubrication fluid between the bearing pad 30a, 30b and the thrust disc 56 increases. An example of a pressure profile is illustrated in Figure 2B by the pressure profile 62. Where the pressure profile 62 is thicker, this indicates a higher pressure, and where the pressure profile 62 is thinner, this indicates a lower pressure. As can be seen, the pressure profile increases in the lateral direction across the bearing surface 34 and peaks off-centre, towards the side of the bearing surface 34 that is located closer to the thrust disc 56. The off-centre peak in pressure additionally has the effect of maintaining bearing surface 34 oriented at an angle between the thrust disc 56 and the bearing surface 34, thereby further permitting the flow of lubrication fluid in the gap 58. The increase in pressure causes the bearing pad 30a, 30b to move further into the cavity 42 in the housing 32, and in this example comes into contact with the protrusion 52. In other examples, or where there is an alternative pressure distribution (for example due to faster/slower rotation of the thrust disc, or a different lubrication fluid being used) the engagement surface 36 of the bearing pad 30a, 30b may additionally, or alternatively, contact the pad engagement surface 50.

The increase in pressure in the gap 58 additionally has the effect of releasing the engagement between the shoulder arrangement 38 and the retainer arrangement 46, as the bearing pad 30a, 30b is moved further into the cavity 42 in the housing 32. As is illustrated in Figure 2B, during operation there may be no engagement between the retainer arrangement 46 and the shoulder arrangement 38. In some other examples or instances, for instance where the rotation of the thrust disc 56 is relatively slow, there may be engagement between a part of the shoulder arrangement 38 and the retainer arrangement 46. Due to the limited engagement while the thrust disc 56 is rotating, engagement between the retainer arrangement 38 and the shoulder arrangement 46 may principally be of benefit during times where there is no rotation between the thrust disc 56 and the thrust bearing 10, as it assists to hold the bearing pad 30a, 30b at an angle relative to the surface 40 of the thrust disc 56, thereby promoting lubricant fluid flow in the gap 58 therebetween.

Although Figures 2A and 2B illustrate the thrust bearing 10 on a single side of the thrust disc 56, there may be an equivalent configuration on the opposing face of the thrust disc 56, for example as is illustrated in Figure 1. Having an opposing equivalent configuration may permit the thrust bearing 10 to hold a drive shaft in place no matter in which axial direction the thrust force is experienced. Such a thrust bearing may be considered to be bidirectional, as it is able to operate in a desirable manner while experiencing thrust forces in two axial directions.

In Figure 2C there is illustrated an axial view of the thrust bearing 10. From the axial view, the shoulder arrangement 46 is more clearly illustrated, as is the shape of the bearing pads 30. As illustrated, the shoulder arrangement 46 comprises a single plate of material that is bolted to the housing 32, which defines a boundary of the cavity 42, and contains the bearing pad 30 between the housing 32 and the shoulder arrangement 46. The thrust bearing 10 comprises multiple bearing pads 30, which are arranged in a circular array around a central axis.

Figures 3A and 3B illustrate a further example of a thrust bearing 110. Some similarities exist between the example of Figures 3A and 3B and the example of Figures 2A and 2B, and therefore alike reference numerals will be used for similar parts, augmented by 100.

As in the previous example, two bearing pads 130a, 130b are illustrated, and as in the previous example, each of the bearing pads 130a, 130b are partially positioned in a housing 132, although in this example, the bearing housing 132 is differently defined, as will be described. As in the previous example, the thrust bearing 110 comprises a retainer arrangement 146 and each of the bearing pads 130a, 130b comprise a shoulder arrangement 138, a bearing surface 134 and an engagement surface 136.

As may be the case in the previous example, the housing 132 is formed of two parts 132a, 132b. The first part 132a forms a base, and provides a largely flat surface, upon which the second part 132b may be secured, and which defines the pad engagement surface 150. The first part 132a additionally permits the attachment of a protrusion 152 thereto. The function of the protrusion 152 is largely similar to that as described in relation to Figures 2A and 28, and for the sake of conciseness will not be described again.

In the example of Figures 3A and 3B, the retainer arrangement 146 is defined on the second part of the housing 132b, which therefore assists to hold each of the bearing pads 130a, 130b in place in the housing, and a cavity 142 may be defined by (e.g. between) the first part and the second parts 132a, 132b of the housing. Here, the second part of the housing 132b is secured to the first part of the housing 132a by a means of a screw or bolt arrangement 154. In contrast to the previous example, there is no contact illustrated between the first part of the housing 132a and the second part of the housing 132b. Instead, the screw or bolt arrangement 154 may secure the second part of the housing 132b relative to the first part of the housing 132a in order to define a cavity therebetween. In the example of Figures 3A and 3B, the cavity in which one bearing pad 130a, 130b is located may merge with the cavity of an adjacent bearing pad 130a, 130b. Although the second part of the housing 132b is illustrated as having no contact with the first part of the housing 132a, there may be some contact between the first and second parts of the housing 132a, 1326 at a location that is not visible in the cross-section of Figures 3A and 3B.

The second part of the housing 132b may be in the form of a flat plate, with one or more apertures therein, for permitting the second part of the housing 132b to engage the screw or bolt arrangement 154, which may hold the second part of the housing 132b in place. Located between the second part of the housing 132b and the screw or bolt arrangement 154 (e.g. located between the head of the screw/bolt arrangement 154 and the second part of the housing 132b) is a biasing member 170, which in this case is a Belleville spring. The biasing member 170, in this example, assists to hold the second part of the housing 132b in a desired position relative to the first part of the housing 132a. The biasing member 170 may additionally or alternatively assist to hold the retainer arrangement 146 in a desired position relative to the first part of the housing 132a. Since, in this example, the second part of the housing 132b defines both the retainer arrangement 146 and the second part of the housing 132b, then the biasing member assists to hold both in a desired position relative to the first part of the housing 132a. The biasing member 170 is able to hold the housing 132b and the retainer arrangement 146 in a desired position as a result of its direct contact with the housing 132b, and the screw/bolt arrangement 154.

As can be seen in the illustration of Figure 3A and 3B, the second part of the housing 132b is positioned such that the retainer arrangement 146 is located closer to the pad engagement surface 150 on one lateral side of the cavity 142 in which the bearing pad 130a, 130b, is contained than on the retainer arrangement 146 on the other lateral side of the cavity 142. In this example, this is as a result of the biasing member 170 holding the retainer arrangement 146 higher on one side of the screw/bolt arrangement 154 than on the other, thereby providing one cavity 142 with a retainer arrangement 146 positioned closer to the pad engagement surface 150 and an adjacent cavity 142 with a retainer arrangement 146 positioned further from the pad engagement surface 150, since the screw/bolt arrangement 154 is located between the cavities of the thrust bearing 110.

In order to position the retainer arrangement 146 with the desired orientation, the biasing member 170 may have an asymmetrical shape, so as to urge one portion of the retainer arrangement 146 closer to the pad engagement surface 150 than another portion, or than a portion of an adjacent retainer arrangement 146, as is the case in the illustrated example. In this example, the biasing member 170 is in the shape of a Belleville spring, such that one side of the spring extends at an angle to the other against the retainer arrangement 146, as is illustrated. An alternative biasing arrangement may be used, for example a washer, or Belleville spring having one side thicker than the other, a conical or cylindrical helical spring, a blade steel spring, an elastomeric spring, or the like. While the biasing member 170 is illustrated as being a separate component from the second part of the housing 132b, in some examples the biasing member may be integrally formed with the second part of the housing 132b.

The second part of the housing 132b may be held in place as the result of an attachment and/or coupling between the screw/bolt arrangement 154, thereby ensuring that the second part of the housing 132b is not able to move axially along the shaft of the screw/bolt arrangement 154. In some examples, there may be a support member located on the shaft of a screw/bolt of the screw/bolt arrangement 154 to additionally prevent or restrict axial movement of the second part of the housing 132b along the shaft of a screw/bolt of the screw/bolt arrangement 154.

As is visible in Figure 3A and 3B, located in a cavity 142 that is defined between the first and second parts of the housing 132a, 132b, and in this example additionally between each screw/bolt of the screw/bolt arrangement 154, is a bearing pad 130a, 130b. As in the previous example, each of the bearing pads 130a, 130b comprises a shoulder arrangement 138. The shoulder arrangement may be in the form of one continuous shoulder that extends around the periphery of the bearing pad 130a 130b, or the shoulder arrangement may be in the form of two or more shoulders that may extend discontinuously around the periphery of the bearing pad 130a, 130b. In some examples the shoulder arrangement may be in the form of a slot located in the bearing pad 130a, 130b, for example a slot machined into the side of the bearing pad 130a, 130b. In such cases, the slot may form one discontinuous shoulder arrangement 138 in the bearing pad 130a, 130b.

As in the previous example, the shoulder arrangement 138 engages the retainer arrangement 146. The engagement between the shoulder arrangement 138 and the retainer arrangement 146 assists to hold the bearing surface 134 of each bearing pad 130a, 130b at an (non-zero) angle relative to a surface 140 of the thrust disc 156, as was the case in the previous example. In this example, the shoulder arrangement 138 is located such that every portion is approximately equidistant from the bearing surface 134, which is in contrast to the previous example. Instead, here the second part of the housing 132b is held at an (non-zero) angle relative to the first part of the housing 132a, which in turn holds the retainer arrangement, which in this example is defined by the second part of the housing 132b, at an angle relative to the first part of the housing 132a. As is illustrated in Figures 3A and 3B, the retainer arrangement extends from the screw/bolt arrangement and towards the pad engagement surface 150 on a first lateral side of the cavity 142, but extends away from the pad engagement surface 150 on a second, opposite, lateral side of the cavity 142. As such, and as was the case with the previous example, the engagement between the retainer arrangement 146 and the shoulder arrangement 138 permits the bearing pad 130a, 130b to be held at an angle relative to the surface 140 of the thrust disc 156, thereby promoting the flow of a lubrication fluid therebetween, as has been described.

In this example, the shoulder arrangement 138 comprises a shoulder that protrudes from the bearing pad 130a, 130b. As in the previously described example, the protruding shoulder is partially defined by the engagement surface 136 of the bearing pad 130a, 130b, and is located on the engagement surface-side of the bearing pad 130a, 130b. However, in contrast to the previous example, the bearing pads 130a, 130b provide a corresponding and oppositely disposed shoulder of the shoulder arrangement 138. The oppositely disposed shoulder is at least partially defined by the bearing surface 134, and is located on the bearing surface-side of the bearing pad 130a, 130b. As a result of having an oppositely disposed shoulder, the engagement between the shoulder arrangement 138 and the retainer arrangement 146 may effectively place the retainer arrangement 146 in a slot in the bearing pad 130a, 130b (such as a slot defined in the bearing pad 130a, 130b), which may assist to prevent or restrict the separation between the retainer arrangement 146 and the shoulder arrangement 138, for example when the thrust bearing 110 is in operation.

While Figure 3A illustrates the thrust bearing 110 in a stationary configuration, Figure 38 provides an illustration of the thrust bearing 110 during operation. As was the case in the previous example, the change in pressure of the lubrication fluid acting on the bearing surface 134 is illustrated, and forms a similar profile to that as in Figure 2A. While in the previous example, the bearing pad 30a, 30b was not in engagement with the protrusion 52 of Figures 2A and 2B when the thrust bearing 10 was stationary, in this example the bearing pad 130a, 130b is in engagement with the protrusion 152 in both stationary and operational states. As such, there may be no, or reduced, movement of the bearing pad 130a, 130b upon operation of the thrust bearing 110. In some examples, for example where the orientation of the pump or compressor may change in operation, this may assist the thrust bearing 110 to continue to operate despite the orientation.

The person skilled in the art realises that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the

disclosure, and the appended claims.

Claims

CLAIMS1. A thrust bearing, comprising: a bearing pad comprising a bearing surface for receiving a load from a thrust disc, and an oppositely disposed engagement surface for engaging a bearing housing; a bearing housing comprising a pad engagement surface, and a retainer arrangement disposed on the bearing housing; the bearing pad comprising a shoulder arrangement for engaging the retainer arrangement, the shoulder arrangement being located between the bearing surface and the engagement surface; wherein at least one of: a first portion of the shoulder arrangement is located closer to the bearing surface than a second portion of the shoulder arrangement; and a first portion of the retainer arrangement is located closer to the pad engagement surface than a second portion of the retainer arrangement; such that the bearing surface is oriented at a non-zero angle relative to the thrust disc.
2. The thrust bearing of claim 1, wherein the retainer arrangement comprises a single retainer profile extending in a ring configuration.
3. The thrust bearing of claim 1, wherein the retainer arrangement comprises at least two retainer profiles, each extending around a section of the periphery of the bearing pad.
4. The thrust bearing of claim 3, wherein a first of the at least two retainer profiles is located closer to the pad engagement surface than a second of the at least two retainer profiles.
5. The thrust bearing according to any preceding claims, wherein the retainer arrangement extends in a non-parallel direction to the engagement surface.
6. The thrust bearing according to any preceding claim, wherein the retainer arrangement comprises at least one retainer profile, the at least one retainer profile extending in a non-parallel direction to the engagement surface.
7. The thrust bearing of any preceding claim, wherein the shoulder arrangement comprises a single shoulder extending around the periphery of the bearing pad.
8. The thrust bearing of any of claims 1 to 6, wherein the shoulder arrangement comprises at least two shoulders, each of the at least two shoulders extending around a section of the periphery of the bearing pad.
9. The thrust bearing of any preceding claim, wherein the bearing housing comprises a cavity for receiving at least a part of the bearing pad therein.
10. The thrust bearing of claim 9, wherein the cavity is defined by the bearing housing and the retainer arrangement.
11. The thrust bearing of any preceding claim, when the bearing surface is oriented at an angle of between 0 and 30 degrees relative to the thrust disc.
12. The thrust bearing of any preceding claim, wherein the bearing surface is oriented at an angle of between 3 and 8 degrees relative to the thrust disc.
13. The thrust bearing of any preceding claim, wherein the surface of the thrust disc and the bearing surface are axially separated so as to prevent direct engagement between the bearing surface and the surface of the thrust disc.
14. The thrust bearing of any preceding claim, comprising a plurality of bearing pads, each bearing pad located in a separate bearing housing.
15. The thrust bearing of claim 14, wherein the separate bearing housings are located in a radial or circular array formation.
16. The thrust bearing of any preceding claim, comprising a protrusion on the pad engagement surface for engaging the engagement surface, and permitting pivoting of the bearing pad on the protrusion.
17. The thrust bearing of any preceding claim, wherein the shoulder arrangement comprises a first shoulder and a second, oppositely oriented shoulder, so as to create a slot in the bearing pad.
18. The thrust bearing of claim 17, comprising a washer plate coupled to the housing and configurable to engage with the slot in the bearing pad located between the first and the second shoulders.
19. A method for reducing wear in a thrust bearing, comprising: providing a bearing pad comprising a bearing surface in a bearing housing; providing a thrust disc for exerting a load on the bearing pad; orienting the bearing pad relative to the housing such that the bearing surface is located at a non-zero angle relative to the thrust disc when the thrust disc stationary relative to the bearing pad; rotating the thrust disc relative to the bearing pad, so as to generate a pressure profile in a lubricant fluid.
20. The method according to claim 19 comprising axially separating the thrust disc and the bearing pad to provide a gap and prevent direct contact therebetween.
21. The method according to claim 20 comprising creating a pressure profile in a lubricant fluid located in the gap.