GB2536414A

GB2536414A - Bearing element with selective joint face relief

Info

Publication number: GB2536414A
Application number: GB1503988.6A
Authority: GB
Inventors: Hrdina Daniel; Mian Omar; Gallas Tino
Original assignee: Mahle International GmbH; Mahle Engine Systems UK Ltd
Current assignee: Mahle International GmbH; Mahle Engine Systems UK Ltd
Priority date: 2015-03-09
Filing date: 2015-03-09
Publication date: 2016-09-21
Anticipated expiration: 2035-03-09
Also published as: GB201503988D0; GB2536414B

Abstract

The bearing element 10 comprises a first bearing shell 11 and a second bearing shell 12. Each shell comprising a substrate and a sliding layer. The first bearing shell comprises, at a first end, a first joint face relief portion 23. The second bearing shell comprises, at a second end, a second joint face relief portion 24. The first bearing shell and the second bearing shell are arranged so that the first end of the first bearing shell is proximate the first end of the second bearing shell and the second end of the first bearing shell is proximate the second end of the second bearing shell, the first and second bearing shells forming a bore for receiving a rotatable member. The first and the second joint relief portions are positioned at leading edges of the respective first end of the first bearing shell and the second end of the second bearing shell relative to an intended direction of rotation of a rotatable member positioned within the bore. Each of the first and second joint relief portions forms an undercut portion. Also claimed is an element where the relief portions are substantially the same thickness as the sliding layers. Also claimed is a method of adding a sliding layer material to a number of bearing elements.

Description

BEARING ELEMENT WITH SELECTIVE JOINT FACE RELIEF

FIELD OF THE INVENTION

The invention relates to a bearing element having selective joint face relief. The invention also relates to a method of assembling a bearing element for application of a sliding layer and to a method of applying a sliding layer material to a plurality of bearing elements.

Bearing elements according to preferred embodiments of the present invention are particularly suitable for use in automotive environments, including for supporting rotatable engine components.

BACKGROUND TO THE PRESENT INVENTION

Bearing elements comprising a back, a substrate layer and a sliding layer (or overlay or running layer) are generally known. Such bearings are commonly used in engines, for example as crankshaft and/or camshaft supporting bearings and as big end bearings and small end bushings in connection rods. They may also be used as thrust washers (axial bearings).

Such bearing elements typically comprise a pair of complimentary bearing shells (usually arranged as upper and lower bearing shells) that are brought together to define a bore for receiving and supporting a rotatable shaft. A support structure for the bearing element is commonly provided by two complimentary sections or portions of a housing, for example an engine housing comprising an engine cap and an engine block, or a connecting rod housing, which are brought together around the shaft and the bearing shells provide running surfaces that bear against the shaft.

Such bearing elements require hydrodynamic lubrication in order to maintain a film of lubricating oil in a bearing clearance located between the bearing shells and the rotating shaft. Lubrication is required to prevent direct contact between the running services and the shaft that would otherwise lead to increased friction, elevated temperatures and rapid wear of the bearings and would lead to an increased risk of metal-to-metal contact and eventually seizure of the shaft and/or damage to the crankshaft.

In order to lubricate the bearings, an internal combustion engines typically provided with an oil pump which pumps lubricating oil under pressure into the bearing clearance between the bearing shells and the rotating shaft. The lubrication oil is pumped to the inner face of one or both bearing shells (e.g. into a groove in the inner face of one or both bearing shells).

As bearings elements used in engines are typically comprised of two bearing shells that are brought together to form a bore for a shaft, it is an inherent result of their construction that they permit axial side leakage of oil at the joint faces (the short faces connecting the inner and outer curved surface of each end of each bearing shell which butt against each other when the bearing shells are brought together). This causes oil to pass -1 -from the bearing clearance and away from the running surfaces. Accordingly, engines commonly require oil pumps to have a high flow rate in order to maintain the oil pressure required to maintain a film of oil between the running surfaces and the shaft and in order to avoid the undesirable effects described above.

It is known that during assembly of an engine incorporating a bearing element comprising a pair of bearing shells, there is inevitably a slight misalignment between the respective joint faces when the bearing shells are brought together around a shaft. This is commonly referred to as "cap shift" or "offset shift" and is shown in Figure 1 (taken from Wang, D., Jones, G., and Sturk, B., "A Study of the Influence of Bore Shape on the Performance of a Large-End Bearing," SAE Technical Paper 2001-01-3547, 2001, doi:10.4271/2001-01-3547).

In order to address the known problem of cap shift, it is common practice in the manufacture of bearing elements for engines to provide the inner curved surfaces of the bearing shells with relief regions which extend from the joint faces towards the crown of the bearing shells. This is commonly referred to as "Joint Face Relief", "Crush Relief' or "Bore Relief' and is shown in Figure 2 (also taken from the SAE Technical Paper). As shown in Figure 2, the reduction in the thickness of the bearing shell is known as the "depth of relief' or "bore relief depth" and the portion of the length of the curved surface of the inner face of the bearing shell over which material is removed to reduce the thickness of the bearing shell is known as the "extent of relief" or "relief height".

As shown in Figure 3, it is common practice in the manufacture of bearing elements for engines to provide each bearing shell 1,2 with a relief region 3,4 at both ends of the bearing shell. The relief regions may comprise crush relief regions (bore relief regions) and/or eccentric relief regions. The relief regions adjacent the end faces provide a locally increased bearing clearance, which increases towards the adjacent end face.

Crush relief regions are regions of the concave inner face of the bearing shell in which the bearing clearance is higher, that extends no more than 30° from the adjacent end face, and typically extends no more than 10°. They are commonly used to reduce or eliminate the formation of a step in the assembled bore, at the joint between the pair of complementary bearing shells. Such a step could otherwise arise due to any of: misalignment between complementary bearing shells; wall thickness variations between upper and lower bearing shells; or localised swelling or yielding of a bearing shell at the end face under compression (bearing shells are compressed circumferentially in the assembled bearing, to provide an interference fit with the housing). In the case of a generally semi-cylindrical bearing shell, the crush reliefs are typically regions of reduced wall thickness, on the concave inner surface of the bearing shell, extending from the end faces of the bearing shells.

Eccentric relief regions are longer regions that are machined (e.g. bored) to provide a greater bearing clearance than at the crown (mid-way circumferentially between the end faces). Commonly the eccentric relief regions extend to, or close to, the crown. For example the eccentric reliefs may be machined to be curved about a centre of curvature that is slightly removed from the corresponding bearing shell, relative to the centre of rotation of the shaft, and which has a slightly larger radius of curvature than the separation between the -2 -axis of rotation and the internal face at the crown. Eccentricity controls movement of the shaft, in use, to reduce engine noise, whilst providing adequate oil flow to dissipate heat from the bearing. The eccentric relief regions typically extend no more than 90° from the adjacent end face.

Accordingly, each relief region provides a bearing clearance that is higher (measured along a radius from the axis of rotation of the shaft) than in the crown region. The inventors have appreciated that this known configuration can lead to increased leakage of the lubricating oil from within the bearing clearance, consequently necessitating an oil pump capable of a higher flow rate. Such high flow rate oil pumps have several disadvantages including: energy being wasted by the pump being physically too large and consuming too much engine power to drive it; the oil pump being unnecessarily heavy; and, under some operating conditions (e.g. when starting a cold engine with highly viscous oil, or at high rotational speeds) the pump may provide too much oil pressure and the oil flow may be diverted straight back into the engine sump via an oil pressure relief overflow valve without ever passing through the bearings.

Other prior art bearing elements have sought to address the problem of providing clearance at the joint face to allow for cap shift while also reducing the flow rate of oil from the bearing.

Published international (PCT) patent application number W02012/087876 purports to provide a bearing shell with improved side load capability. It discloses an engine bearing (100) including an upper bearing shell (106) having a first single side relief portion (130) and a lower bearing shell (108) having a second side relief portion (140). The upper bearing shell (106) and the lower bearing shell (108) may be assembled to form a cylindrical bore (112) that is disposed therebetween. It is claimed in the international application that the first and second single side relief portions (130, 140) are configured to compensate for any offset shift that occurs at parting lines (210) located between the assembled upper and lower bearing shells (106, 108).

As described with reference to Figure 3 of the international application which is reproduced at Figure 4 of this application, single side joint face relief (130,140) may be applied at selective portions of the upper and lower bearing shells to alleviate the effects of misalignment of the upper and lower bearing shells during assembly. The single side relief is applied to prevent the formation of any step between the upper and lower bearing shells. The inventor therefore envisages starting with bearing shells that do not have any joint face relief and selectively applying face relief to one side of each bearing shell during manufacture to suit the tolerances of a particular application.

As shown in Figures 2 and 3 of the international application (Figure 3 of the international application being reproduced at Figure 4 of this application) and recited in the claims, the single side relief is required to compensate for any offset shift that occurs at parting lines. It is clear that the inventor of that application intended the bore defined between the upper and lower bearing shells to be circumferential and was seeking to provide a "smoother cylindrical bore". It is also clear that the inventor is seeking to eliminate any sharp corners at the joint face that might otherwise scrape oil from the rotating shaft. -3 -

It is also clear from the international application that the inventor's intention was to apply minimal single sided face relief to each bearing shell that is sufficient only to ensure that the bearing can accommodate offset shift that occurs at parting lines. In other words, the joint face relief is applied so that when the bearing shells are subjected to a maximum offset shift (or cap shift), the bore defined by the bearing shells is both cylindrical and smooth (i.e. free from any step at the joint faces).

The inventors of the present application have appreciated that there may be benefits associated with going against the teaching of the prior art in which it is presented as advantageous to provide a smooth cylindrical bore.

The inventors of the present application have also appreciated that developments in the manufacture of engine components and a reduction in manufacturing tolerances mean that there has been a reduction in the degree of offset shift associated with bearing elements for engines and so there is a reduced need for traditional joint face relief regions.

The inventors of the present application have further appreciated that it may be possible to reduce the number of manufacturing steps that are required to produce bearing shells when compared to prior art bearing shells 1,2 of the type shown in Figure 3 which have joint face relief 3,4 at both ends of each bearing shell, and to reduce the associated manufacturing costs.

The prior art also includes published US patent application number U52009/0169141 which provides a connecting rod bearing for internal combustion engines. The bearing is provided with crush relief areas at both ends of each of the upper and lower bearing shells. The bearing shells are also provided with circumferential grooves 24C and 26F which lead to the joint faces. The circumferential grooves are deliberately provided in the trailing edges of each bearing shell so as to enable lubricating oil to be forced from the bearing clearance to the joint faces to facilitate removal of loose particles.

A method of manufacturing bearing elements is described in detail in the applicants' co-pending UK patent application numbers GB1321671.8 and GB1411314.6. The method described in the earlier applications is also generally suitable for manufacturing bearing elements according to the present invention. However, the inventors have appreciated that there is a need for a modified form of the manufacturing method described in the co-pending applications for manufacturing bearing elements according to preferred embodiments of the present invention that minimises or eliminates application of a sliding layer material to the end faces of the bearing shells.

SUMMARY OF THE PRESENT INVENTION

In the following description, the term "joint face relief" is used to refer to a reduced thickness portion of each bearing shell. The term is used to refer to the known manner of tapering the end portion of a bearing shell towards the joint face so that the bearing shell is thinner at the joint face than over a bulk of the bearing shell, as shown in Figure 2 in relation to the prior art and in Figure 7 in relation to preferred embodiments of the present invention (see left hand upper part of the Figure). The term "joint face relief" is also used to refer to a reduced thickness portion resulting from the use of a mask to prevent a portion of the sliding -4 -layer from being deposited on an underlying layer and leave a portion of the underlying layer exposed, as shown in Figure 7 in relation to preferred embodiments of the present invention (see left hand upper part of the Figure), which results in a more defined step down in the running surface of the bearing shells. It will be appreciated that both of these types of "joint face relief" have a "depth of relief" and a "relief height" ("or extent of relief") as described above with reference to Figure 2 and shown in Figure 7.

The present invention is defined in the appended independent claims and provides, in a first aspect, a bearing element, comprising: a first bearing shell comprising a first substrate and a first sliding layer; a second bearing shell comprising a second substrate and a second sliding layer; wherein the first bearing shell comprises at a first end, a first joint face relief portion; wherein the second bearing shell comprises at a second end, a second joint face relief portion; wherein the first bearing shell and the second bearing shell are arranged so that the first end of the first bearing shell is proximate the first end of the second bearing shell and the second end of the first bearing shell is proximate the second end of the second bearing shell, the first and second bearing shells forming a bore for receiving a rotatable member; wherein the first and the second joint relief portions are positioned at leading edges of the respective first end of the first bearing shell and the second end of the second bearing shell relative to an intended direction of rotation of a rotatable member positioned within the bore; and wherein each of the first and second joint relief portions forms an undercut portion.

The present invention provides, in a second aspect, a bearing element, comprising: a first bearing shell comprising a first substrate and a first sliding layer; a second bearing shell comprising a second substrate and a second sliding layer; wherein the first bearing shell comprises at a first end, a first joint face relief portion; wherein the second bearing shell comprises at a second end, a second joint face relief portion; wherein the first bearing shell and the second bearing shell are arranged so that the first end of the first bearing shell is proximate the first end of the second bearing shell and the second end of the first bearing shell is proximate the second end of the second bearing shell, the first and second bearing shells forming a bore for receiving a rotatable member; wherein the first and the second joint relief portions are positioned at leading edges of the respective first end of the first bearing shell and the second end of the second bearing shell relative to an intended direction of rotation of a rotatable member positioned within the bore; and wherein a depth of relief of at least one of the first and second joint face relief portions is substantially equal to a thickness of the respective first and second sliding layer.

A bearing element according to preferred embodiments of the present invention in the first or second aspect are believed to provide a number of advantages over prior art bearing elements.

First, a bearing element according to preferred embodiments of the present invention which a joint face relief portion provided at one end of each bearing shell, reduces the number of manufacturing steps compared to known bearing shells, such as those shown in Figure 3 to which joint face relief (130,140) is applied to both ends 3,4 of each bearing shell 1,2. Bearing elements according to preferred embodiments of the present invention may -5 -therefore be manufactured using fewer steps and at a lower cost than some known bearing elements.

Second, a bearing element according to preferred embodiments of the present invention may advantageously enable an engine to operate with a lower volume flow rate of oil compared to known bearing elements incorporating joint face relief at both ends of each bearing shell, such as those shown in Figure 3. It is understood that a reduction in oil flow in the region of about 5% may result from a joint face relief portion at only one end of each of the first and second bearing elements compared to a known bearing having joint face relief portions at both ends of each bearing shell, such as those shown in Figure 3.

Third, a bearing element according to preferred embodiments of the present invention may advantageously provide tolerance to cap shift or offset shift that is at least comparable with, and potentially better than, known bearing elements incorporating joint face relief (130,140) at one end of each bearing shell such as those shown in Figure 4.

Fourth, a bearing element according to preferred embodiments of the present invention may advantageously provide improved load carrying capacity proximate the joint faces compared to known bearing elements incorporating joint face relief at both ends 3,4 of each bearing shell 1,2 such as those shown in Figure 3.

Fifth, a bearing element according to preferred embodiments of the present invention may advantageously provide an escape route proximate the joint faces for small particles (including, for example, debris or particles released from the running surface of the bearing shells due to wear, dirt, or swarf passing from engine block drillings or other engine components) to be carried away from the running surface by the lubricating oil that is at least comparable with, and potentially better than, known bearing elements incorporating joint face relief (130,140) at one end of each bearing shell, such as those shown in Figure 4.

Some preferred features of the present invention in the first aspect are set out in the dependent claims to which reference should now be made and are also described below.

Preferably, a depth of relief of each undercut portion is sufficient to accommodate cap shift or offset shift that may occur between the first and second bearing shells during assembly of the bearing element. More preferably, a depth of relief of each undercut portion is sufficient to accommodate any offset shift between the first and second bearing shells and still provide a residual undercut portion. This may enable the bearing element to benefit from the advantages listed above, among others, even when there is some offset shift during the assembly of the bearing element. It may also eliminate a risk associated with known bearings than an offset shift may create a leading edge that protrudes into the bore and scrapes oil from the running surface which can result in ineffective hydrodynamic lubrication.

Preferably, a depth of relief of the first joint face relief portion is substantially equal to an average thickness of the first sliding layer and a depth of relief of the second joint face relief portion is substantially equal to an average thickness of the second sliding layer.

Some preferred features of the present invention in the first or second aspects are set out in the dependent claims to which reference should now be made and described below. -6 -

Preferably, the first and second joint face relief portions extend across an entire width of the respective first and second bearing shells. This may help to ensure effective lubrication of the running surface and may help to facilitate removal of loose particles.

Preferably, each of the first and second bearing shells has a uniform thickness over the first and second joint face relief portions.

Preferably, a depth of relief of at least one of the first and second joint face relief portions is greater than a thickness of the respective first and second sliding layer. This may help to ensure that even when there is offset shift of the first and second bearing shells, there is a residual undercut portion, particularly as the sliding layer wears, which may provide the advantages described above.

An average thickness of the sliding layer is preferably between about 3pm and about 25pm. An average thickness of the sliding layer is preferably between about 5pm and about 15pm An average thickness of the sliding layer is preferably between about 6pm and about 12pm. An average thickness of the sliding layer is preferably between about 7pm and about 11pm.

The first and second joint face relief portions may be applied to the substrate of the first and second bearing shells before the sliding layer is applied. Alternatively, the first and second joint face relief portions may be generated by machining some or all of: the sliding layer; a lining layer applied to the substrate and an intermediate layer applied to the lining layer onto which the sliding layer is applied.

Preferably, the bearing element may be configured so that a depth of relief of each of the first and the second joint face relief portions is greater than an average thickness of the sliding layer. More preferably, the bearing element may be configured so that a depth of relief of each of the first and the second joint face relief portions is greater than an average thickness of the sliding layer. This may help to ensure that even when there is offset shift of the first and second bearing shells, there is a residual undercut portion which may provide the advantages described above.

Preferably, the bearing element is be configured so that a minimum depth of relief of each of the first and the second joint face relief portions is between about 4pm and about 8pm, preferably between about 5pm and about 7pm. The bearing element may alternatively be configured so that a minimum depth of relief of each of the first and the second joint face relief portions is between about 6pm and about 12pm, preferably between about 8pm and about lOpm.

The bearing may be configured so that a relief height of each joint face relief portion is between about 1 and about 12mm, more preferably between about 3 and about 9mm, more preferably between about 6 and about 8 mm.

At least one of the first and second joint relief portions may be formed by removal of material from the respective first or second bearing shells. For example, at least one of the first and second joint relief portions may be formed by removal of material from the respective first or second substrate prior to application of the sliding layer. Alternatively, at least one of the first and second joint relief portions may be formed by removal of material -7 -from a lining layer applied to the respective first or second substrate prior to application of the sliding layer. Alternatively, at least one of the first and second joint relief portions may be formed by removal of material from an intermediate layer applied to the substrate or to a lining layer prior to application of the sliding layer.

Alternatively, at least one of the first and second joint relief portions may be formed by masking of the respective first and second bearing shell. For example, the substrate (or a lining layer and/or intermediate layer applied to the substrate) may be masked so that the sliding layer material is applied to a portion of the first or second bearing shell but is not applied to the first and/or second joint relief portion as removal of the mask removes the portion of the sliding layer that is applied to the mask, leaving a portion of the underlying substrate (or a lining layer and/or intermediate layer applied to the substrate) exposed.

Preferably, the sliding layer material is a polymer coating or sputter coating. Preferably, a polymer coating is sprayed or printed onto the substrate. Other, sliding layer materials may also be used, including metallic sliding layer materials which may, for example, be deposited by a process of electroplating.

Preferably, the first bearing shell and the second bearing shell are identical. This may be most practical where the sliding layer material is a polymer based sliding layer material. This may reduce the cost of manufacturing the bearing elements by enabling a first bearing element to be rotated to form a second bearing element. Preferably, at least one of the first and second bearing shells is provided with a distinguishing mark (or poka yoke).

This may help them to be positioned appropriately (e.g. to be arranged as upper and lower bearing shells).

The substrate may comprise a backing layer and/or a bearing lining layer on the concave face of the backing layer. The substrate may optionally have one or both of: an overlay layer on the concave face of the bearing lining layer; and, one or more intermediate layers between the bearing overlay and the lining layer.

A suitable bearing shell may have a steel backing, a bearing lining layer of an aluminium-based or copper-based alloy (including a copper-tin bronze-based alloy), an optional interlayer, and a polymer overlay, or running layer which may be applied to the bearing lining layer or interlayer by spraying or printing. The overlay may alternatively be a metal-based overlay layer which may be deposited by electro-plating or sputtering.

The curved inner surface of the bearing shells typically requires a running surface which has a suitable balance of hard properties, including wear resistance and fatigue resistance, and soft properties, including seizure resistance, and enhanced conformability and embeddability. Accordingly, the bearing lining layer, or any overlay layer, provides the running surface of the bearing shell. Typically, bearing shells with aluminium based alloy bearing lining layers may provide suitable running surfaces and may not require an overlay. In contrast, copper-based alloys of bearing shells with copper-based alloy bearing lining layers may not provide suitable properties for a running surface, and may therefore be provided with an overlay. Other suitable overlay materials will be readily apparent to the skilled person. -8 -

Suitable overlay materials may include any of the following: Polyamide-imide resin, acrylate resin, epoxy resin, fluoropolymer (e.g. PTFE), or any combination of these materials. Other suitable materials will be readily apparent to the skilled person. The polymer may comprise a composite of a plastics polymer matrix with particulate. The particulate may be hard particulate (e.g. ceramic powder, silica, and metal powder such as aluminium flakes) and/or soft particulate (e.g. MoS2 and graphite, and fluoropolymer such as PTFE). The polymer may comprise a matrix of a Polyamide-imide plastics polymer material and having distributed throughout the matrix: between about 5 and about 15%vol of a metal powder; between about 1 and about 15%vol of a fluoropolymer, the balance being the Polyamide-imide resin apart from incidental impurities.

Bearing elements according to preferred embodiments of the invention may be particularly suitable for use in fluid-lubricated applications. Particularly advantageous applications for the bearing elements are as sliding bearings in combustion engines, for example crankshaft and/or camshaft supporting bearings, big end bearings and small end bushings. Bearing elements according to preferred embodiments of the invention may be particularly suitable for use in vehicle engines, including those equipped with stop-start engine technology in which the engine is subjected to a substantially greater number of starts over the life of the engine than in conventional engines and in which the crankshaft is regularly accelerated from rest before a uniform hydrodynamic film of lubricant is established on the bearing/running surface.

Bearing elements according to preferred embodiments of the invention may also be used to form any of a number of sliding surfaces on engine components, including bushes, piston skirts, piston rings, liners, camshafts and conrods. They may also be used as, or as part, of any of thrust washers, flanges and half liners. Other suitable applications are envisaged and will be readily apparent to the skilled person.

As discussed above, the inventors have realised that some modification of the method of manufacturing bearing elements described in detail in the applicants' co-pending UK patent application numbers GB1321671.8 and GB1411314.6 would be beneficial. In particular, the inventors have appreciated that positioning bearing elements together in their in-use configuration (shown Figure 6) in which the undercut portions leaves a portion of the joint faces exposed has the potential to lead (during step G of the method described in the co-pending applications), to overspray or overprinting of an overlay or sliding layer material onto an exposed portion of the joint faces. This may have a number of disadvantages, including: unnecessary use of the sliding layer material in coating a portion of the joint faces which does not provide a running surface for the shaft; resistance of the bearing shells to offset shift in order to find their most natural position during assembly of the bearing element due to the partial coating of the joint faces forming a step in the surface of the joint face; build-up of the polymer based overlay in the corner of the undercut portions; and uneven contact between the ends of the bearing shells at the joint faces due to the partial coating of the joint faces forming a step in the surface of the joint face. The inventors have therefore sought to modify the earlier method.

The present invention also provides, in a third aspect, a method of assembling a bearing element for application of a sliding layer, comprising the steps of: providing a first -9 -bearing shell comprising at a first end a first joint face relief portion; providing a second bearing shell comprising at a second end a second joint face relief portion; and positioning the first bearing shell and the second bearing shell so that the joint faces of the first and second bearing shells are substantially aligned and so that the respective first and second joint face relief portions are proximate one another.

This method can be applied to all half shell bearing types irrespective of the sliding layer material and lining layer material to applied to the steel backing.

The present invention also provides, in a fourth aspect, a method of applying a sliding layer material to a plurality of bearing elements comprising the steps of providing a plurality of first bearing shells, each first bearing shell comprising at a first end a first joint face relief portion; providing a plurality of second bearing shells, each second bearing shell comprising at a second end a second joint face relief portion; positioning the plurality of first bearing shells adjacent the plurality of second bearing shells so that each first bearing shell is aligned with a second bearing shell forming a column of bearing shells having a hollow core and so that the respective first and second joint face relief portions of each first and second bearing shell are aligned.

Again, this method can be applied to all half shell bearing types irrespective of the sliding layer material and lining layer material to applied to the steel backing.

This method ensures that the end faces of the first bearing shell are aligned with and covered by the end faces of the second bearing shell. This may serve to reduce or eliminate a risk of application of an overlay or running layer material onto a portion of either or both of the end faces of either or both of the first and second bearing shells.

Some preferred features of the present invention in the fourth aspect are set out in the dependent claims to which reference should now be made and described below.

Preferably, the sliding layer material is sprayed onto the column of bearing shells.

Alternatively, the sliding layer material may be printed onto the column of bearing shells. These methods are particularly suitable where the sliding layer material is a polymer based sliding layer material.

Preferably, the sliding layer material is sprayed onto the column of bearing shells by a spray lance (or nozzle) which is advanced linearly along, and rotated relative to, the column of bearing shells. Preferably, the sliding layer material is continuously rotated relative to the column of bearing shells. Rotating the spray lance relative to the column of bearing shells can ensure greater control over the spraying operation than other spraying known geometries Preferably, the spray lance is angled at between about 30 and about 70 degrees to the normal to the column of bearing shells.

Preferably, a spray cone produced by the spray lance is divided equally by the normal to the surface of the column of bearing shells. For example, a 50° spray angle would form a spray cone covering about 25° on either side of the normal. This may provide improved thickness control of the sliding layer material.

-10 -Preferably, the rotating spray lance is advanced linearly along the column of bearing shells at variable linear velocity. This may be controlled according to a predetermined velocity profile. This may provide improved thickness control of the sliding layer material on the substrates and reduce sagging or running of the sliding layer material relative to the substrates.

Preferably, the method further comprises the step of indexing (i.e. moving through a predetermined angle of rotation) the column of bearing shells between at least two linear advancements of the spray lance relative to the column of bearing shells (e.g. between two complete passes of the spray lance along the centre of the column of bearing shells). This may provide improved thickness control of the sliding layer material and reduce sagging or running of the sliding layer material.

It should be appreciated that any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments of the present invention will now be described with reference to the accompanying drawings, in which:-Figure 1 shows a pair of prior art bearing shells (arranged as upper and lower bearing shells) which have been assembled with an offset shift or cap shift; Figure 2 shows the "depth of relief' and the "relief height" dimensions of a joint face relief portion applied to a prior art bearing shell to combat the effects of offset shift; Figure 3 shows a pair of prior art bearing shells which have been assembled with an offset shift or cap shift and subjected to joint face relief to remove a portion of the bearing surface so as to provide a smooth, cylindrical, running surface for a shaft rotating within a bore defined between the bearing shells; Figure 4 shows a pair of prior art bearing shells which have been subjected to joint face relief at both ends of each bearing shell, thereby providing an elliptical running surface for a shaft rotating within a bore defined between the bearing shells; Figure 5 shows a pair of bearing shells forming part of a bearing element according to a first preferred embodiment of the present invention; Figure 6 shows first and second bearing shells forming part of a bearing element according to the first preferred embodiment of the present invention; Figure 7 shows a bearing element according to the first and a second preferred embodiments of the present invention; Figure 8 shows a bearing element according to the first preferred embodiment of the present invention in which the first and a second bearing shells have been assembled to form a bore; Figure 9 shows a bearing element according to the first preferred embodiment of the present invention in which the first and a second bearing shells have been assembled to form a bore and include a degree of offset shift; Figure 10 shows a bearing element according to the first preferred embodiment of the present invention in which the second bearing shell has been rotated so as to align and match the end faces of the first bearing shell with the correspondingly shaped end faces of the second bearing shell in order to improve a process of application of an overlay or running layer to a substrate of the first and second bearing shells; and Figure 11 shows the general arrangement of a spray lance for applying a sliding layer material to the substrates of a stack of bearing elements according to preferred embodiments of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

As shown in Figure 5, a bearing element 10 according to a first preferred embodiment of the present invention comprises a first bearing shell 11 and a second bearing shell 12. Each of the first and second bearing shells comprises a substrate 13 and a sliding layer 14 which is applied to, and supported by, the substrate. Each bearing shell is preferably also provided with backing layer 15 underlying the substrate to provide increased stiffness and hoop strength.

The bearing shell substrate 13 is preferably made from a metallic material to give the bearing shell greater structural rigidity. Suitable substrate materials include aluminium, bronze, brass, bismuth, copper, nickel, tin, zinc, silver, gold and iron, or alloys of such materials. The substrate may also comprise an alloy of two or more of these materials. Particularly suitable substrate materials for bearing shells according to preferred embodiments of the present invention include iron, aluminium, copper, bronze brass and iron, aluminium, copper, bronze and brass alloys. Other suitable materials are envisaged and will be readily apparent to the skilled person.

Optionally, the substrate 13 may comprise an intermediate layer which may provide an improved surface for adhesion of the sliding layer when certain supporting materials are used. Suitable materials for the optional intermediate layer include nickel, silver, copper and/or iron or alloys comprising one or more of such materials. The optional intermediate layer may comprise a combination of two or more or such materials/alloys. The intermediate layer may also include an adhesion promoter and/or be subjected to a pre-treatment, for example a phosphating, chromating or silicating treatment. Other suitable materials are envisaged and will be readily apparent to the skilled person.

-12 -The sliding layer 14 is formed of a sliding layer material and is formed on the underlying substrate to give the bearing shell the desired bearing characteristics e.g. the desired load carrying capacity and wear resistance. The matrix of the sliding layer material (which generally provides the highest volume percentage portion of the sliding layer material) is formed of a polymeric material. Examples of suitable polymeric materials include or may comprise: cross-linkable bonding agents; thermosetting plastics; high melting point thermoplastics; materials having a matrix of at least one high melting point thermoplastic material; fibre-reinforced plastics; any combination of these materials. Other suitable materials are envisaged and will be readily apparent to the skilled person. Particularly suitable polymeric materials include: PAI (Polyamide-imide); PI (Polyimide); epoxy; epoxy resin; phenolic resin; silicone resin; polyether ether ketone or a combination of any of these materials. These materials are characterised by high temperature resistance and excellent media resistance (such as chemical resistance to lubricants). One particularly preferred polymeric material for bearing shells embodying the present invention is polyamide imide (PAI).

The sliding layer material may optionally include at least one solid lubricant. Suitable solid lubricants include: metal sulphides with layered structures; graphite; hexagonal boron nitride (h-BN); molybdenum disulfide (MoS2); tungsten disulphide (WS2); PTFE; or a combination of any of these materials. Other suitable materials are envisaged and will be readily apparent to the skilled person.

The sliding layer material may optionally include at least one hard particle provide improved wear resistance. Suitable hard particles include, for example, ceramic powders, silica, alumina other metal powders. Other suitable materials are envisaged and will be readily apparent to the skilled person.

The sliding layer material may optionally include one or more additional materials in order to tailor its properties to a particular application, as will be readily apparent to the skilled person.

The backing layer 15 is preferably made from steel. Other suitable materials will be apparent to the skilled person.

Figure 6 is a simplified view of a first bearing shell 11 and a second bearing shell 12 forming part of a bearing 10 element according to the first preferred embodiment of the present invention. A first end 16 of the first bearing shell (at the left hand side of Figure 6) is provided with a first joint face relief portion 17. The joint face relief portion has a depth of relief and a relief height (see Figure 2). A second end 18 of the first bearing shell (at the right hand side of Figure 6) does not have any joint face relief portion and therefore has a constant thickness that is consistent with the bulk of the bearing shell. In other words, the first bearing shell has a joint face relief portion at only one end.

In addition to the joint face relief the bearing shell may be provided with a degree of eccentricity which gives the bearing shell the greatest thickness in the crown region and then decreases towards the joint face. Eccentricity may be used to counteract distortion upon bolting the bearing housing with the two half-shells together.

-13 -A second bearing shell 12 forming part of a bearing element according to the first preferred embodiment of the present invention has a very similar structure to the first bearing shell, subject to any modifications described elsewhere in this specification. A second end 19 of the second bearing shell (at the right hand side of Figure 6) is provided with a second joint face relief portion 20. The second joint face relief portion has a depth of relief and a relief height (see Figure 2). A first end 21 of the second bearing shell (at the left hand side of Figure 6) does not have a joint face relief portion and therefore has a constant thickness that is consistent with the bulk of the bearing shell. In other words, the second bearing shell has a joint face relief portion at only one end.

Figure 7 shows a portion of a bearing element according to the first preferred embodiment of the present invention -see upper left hand side of the Figure. The first joint face relief portion and/or the second joint face relief portion may be generated by machining of the overlay and/or lining material. Alternatively, the first joint face relief portion may be generated by machining of the bearing shell substrates prior to application of the overlay or running layer. Suitable methods for generating the first and second joint face relief portions will be readily apparent to the skilled person.

Figure 8 shows a bearing element 10 according to preferred embodiments of the present invention. The first 11 and second 12 bearing shells have been brought together at their joint faces to define a bore 22 for receiving a rotatable shaft, for example a driveshaft or camshaft. The first joint relief portion 17 and the second joint relief portion 20 are respectively provided on internal surfaces (i.e. on the running surfaces) of the first 11 and second 12 bearing shells. The first joint face relief portion and the second joint face relief portion are respectively provided on opposite sides of parting lines located between the first and second bearing shells. The first and the second joint face relief portions are substantially diametrically opposed i.e. they are on substantially diametrically opposite sides of the bore.

Each of the first 17 and second 20 joint face relief portions forms an undercut portion 23,24 proximate the first and second ends of the bearing shells. The inner surface of the bearing steps down at each of the joint faces relative to the direction of rotation of the shaft.

In other words, the trailing edge of each bearing shell forms an overhang which overhangs the leading edge of each of the other bearing shell. As described above, this undercut is understood to provide a number of advantages over prior art bearing elements which do not have any joint face relief or which have joint face relief at both ends of each of the bearing shell.

Figure 8 shows the intended direction of rotation 25 of a shaft positioned within the bore and supported by the first and second bearing shells. It will be appreciated that the first and second bearing shells are arranged so that the first and second joint relief portions are positioned at the leading edges of the first and second bearing shells relative to the intended direction of rotation of the shaft. In other words, when the rotatable member is rotated in a the direction indicated in Figure 8, a point on the surface of the rotatable member passes parting line 26 immediately before it passes the undercut portion 23 and the rotatable member passes parting line 27 immediately before it passes the undercut portion 24.

-14 -Figure 7 also shows a portion of a bearing element according to a second preferred embodiment of the present invention -see lower left hand side of the Figure. This embodiment is very similar to the first preferred embodiment, however the first and second joint face relief portions are formed in a different way to those of the first preferred embodiment. Instead of removing material from the first and second bearing shells, in particular removing material from the substrate (or, the optional lining layer or optional intermediate layer), the first and second joint face relief portions are formed by masking the bearing shells prior to application of the sliding layer. A suitable mask may be positioned on the substrate, or the optional lining layer or optional intermediate layer. Therefore, when the sliding layer is applied to the substrate (or lining layer or intermediate layer), a larger portion of the sliding layer is applied to the substrate (or lining layer or intermediate layer) and a smaller portion of the sliding layer is applied to the mask. When the mask is removed, a portion of the underlying layer is exposed. The mask thereby forms a step in surface of the overlay or running layer. In other words, each of the first and second bearing shells is thinner in the masked region than over the remainder of the bearing shell.

It will be appreciated that bearing shells of this second preferred embodiment therefore have a similar structure to that of the first preferred embodiment, including a joint face relief portion -(i.e. a reduced thickness portion) -at one end of each of the first and second bearing shells. However, instead of forming the joint face relief portion by applying, and then removing, material from each bearing shell as in the first preferred embodiment, in this second preferred embodiment, the joint face relief portion is formed by preventing a portion of the sliding layer material from being applied to each bearing shell during manufacture. It will also be appreciated that the shape of the joint face relief portions of this second preferred embodiment is slightly different to the shape of the joint face relief portions of the first preferred embodiment. In the first preferred embodiment, the joint face relief portions are preferably slanted/angled as a result of the respective bearing shell getting thinner towards the joint face. However, in the second preferred embodiment, the joint face relief portions result from a more defined step in the running surface caused by removal of the mask. Although the joint face relief portions of the first and second preferred embodiments have a different shape, it will be appreciated that they both have a depth of relief and a relief height and any description elsewhere in this specification relating to the depth of relief and a relief height of the joint face relief portions of the first preferred embodiments also relates to the second preferred embodiment.

The second preferred embodiment involving the use of a mask to cover a portion of the underlying bearing shell may enable any of the following types of coatings to be used: a polymer coating; a sputter coating; an electroplated coating.

A depth of relief 28 of the first and second joint face relief portions of the first and second preferred embodiments is sufficient to accommodate cap shift or offset shift of the first 11 and second 12 bearing shells that may occur during assembly of the bearing element. As such, if there is misalignment between the first and second bearing shells during assembly of the bearing shells as shown in Figure 9, the undercut portions 23,24 are sufficient to prevent the joint face of the first end of the first bearing shell, or the joint face of the second end of the second bearing shell from protruding into the bore and providing an edge or corner which could serve to scrape oil from the rotating shaft and thereby adversely -15 -affect hydrodynamic lubrication of the bearing element. It will be appreciated that an offset shift between the first and second bearing shells will cause the area of the undercut portions to be reduced, but the depth of relief 28 of the first and second joint face relief portions is sufficient that there will always remain a residual undercut at the leading edge of each of the bearing shell even after the offset shift that will still provide the advantages described above.

In order to accommodate offset shift and provide a residual undercut, the depth of relief of each of the first and second joint face relief portions is preferably in the region of 1-30pm. The desired depth of relief is expected to vary with the type of overlay or running layer. For example, for a polymer or sputter overlay, a depth of relief is preferably between about 3pm and about 25pm, more preferably between about 5pm and about 15pm, more preferably between about 6pm and about 12pm, more preferably between about 7pm and about 11pm, more preferably between about 5pm and about 7pm. For an electroplated coating is used, a thickness of the overlay may need to be higher than a thickness of a polymer or sputter coating. A thickness of an electroplated coating may preferably be in the region of between about 20pm about 40pm, more preferably between about 25pm about 35pm..

The depth of relief and relief height of each of the first and second bearing shells of the first and second preferred embodiments may be dependent on the bearing diameter and may increase in line with the bearing diameter as is known in relation to coatings for prior art 20 bearings.

As described above, the applicants' co-pending UK patent application numbers GB1321671.8 and GB1411314.6 describe a method ("the earlier method") of manufacturing a bearing shell comprising some, or all, of the following steps:-A. degreasing the substrate; B. roughening the surface of the substrate; C. washing the substrate; D. assembling of a plurality of substrates for application of the sliding layer material; E. pre-heating of the assembled substrates; F. pre-heating of the sliding layer material G. application of the sliding layer material to the surface of the assembled substrates; H. drying of the sliding layer material; I. additional passes of the bearing elements -for example through previous steps G to H only or through any of steps C to H, as required; J. curing (or hardening) of the sliding layer material; and K. post-process cleaning (washing) of the bearing elements.

The earlier method is also generally suitable for manufacturing the first and/or second bearing shells forming bearing elements according to the first preferred embodiment of the present invention, but requires some modification as will now be discussed.

In a first preferred embodiment of the present method ("the present method"), as a preliminary step (i.e. prior to step A of the earlier method), the bearing shell substrates are -16 -formed by cutting them from sheet material and bending or rolling them to give them their semi-cylindrical structure. The bearing substrates are then machined using a suitable process to provide a joint face relief portion at one end of each bearing shell.

In the present method and as described in step D of the earlier method, a plurality of first bearing shell substrates to which the joint face relief portion at one end has been applied is positioned side-by-side and a plurality of second bearing shell substrates to which the joint face relief portion at one end has been applied is positioned side-by-side, each plurality forming an elongate semi-cylindrical structure. The two elongate semi-cylindrical structures of bearing shells are then brought together to form a column 29 of bearing shells having a hollow core as shown in Figure 11.

In the present method, step D of the earlier method is modified so that the first end of each of the first bearing shells is positioned adjacent the second end of each of the second bearing shells and the second end of each of the first bearing shells is positioned adjacent the first end of each of the second bearing shells. As shown in Figure 10, this ensures that the joint faces of each of the first bearing shells are matched with the correspondingly shaped joint faces of each of the second bearing shells, which have substantially the same area.

This modified step of the present method ensures that during step G of the earlier method (i.e. application of the sliding layer material to the surface of the assembled bearing shell substrates by spraying of the sliding layer material onto the substrate), overspray by a spray lance 30 of the sliding layer material onto the end faces of the first and second bearing shells is reduced or eliminated.

In the first preferred embodiment of the present method described above, the sliding layer material is sprayed onto the whole of the inner surface of the substrates (or to any lining layer and/or intermediate layer that is required and has been applied to the substrate), including over the first and second joint relief regions. As a result, a thickness of the sliding layer material is substantially constant (subject to the normal fluctuations in the thickness of the sliding layer) over the entire inner surface of the substrate of the first and second bearing shells, including over the first and second joint relief regions.

In a second preferred embodiment of the present method, as a preliminary step (i.e. prior to step A of the earlier method), the bearing shell substrates are formed by cutting them from sheet material and bending or rolling them to give them their semi-cylindrical structure but the bearing substrates are not machined to provide a joint face relief portion at one end of each bearing shell. After fabrication of the substrate, a lining layer (and, if required, an intermediate layer) are applied using known techniques to the substrate to form a surface on which to deposit the sliding layer in step D of the earlier method. The lining layer and/or the intermediate layer (if an intermediate layer is present) is then machined using a suitable process to provide a joint face relief portion at one end of each bearing shell.

In the second preferred embodiment of the present method and as described in step D of the earlier method, a plurality of first bearing shell substrates to which the joint face relief portion at one end has been applied is positioned side-by-side and a plurality of second bearing shell substrates to which the joint face relief portion at one end has been applied is -17 -positioned side-by-side, each plurality forming an elongate semi-cylindrical structure. The two elongate semi-cylindrical structures of bearing shells are then brought together to form a column 29 of bearing shells having a hollow core as shown in Figure 11.

In the second preferred embodiment of the present method, step D of the earlier method is modified so that the first end of each of the first bearing shells is positioned adjacent the second end of each of the second bearing shells and the second end of each of the first bearing shells is positioned adjacent the first end of each of the second bearing shells. As shown in Figure 10, this ensures that the joint faces of each of the first bearing shells are matched with the correspondingly shaped joint faces of each of the second bearing shells, which have substantially the same area.

This modified step of the second preferred embodiment of the present method ensures that during step G of the earlier method (i.e. application of the sliding layer material to the surface of the assembled bearing shell substrates by spraying of the sliding layer material onto the substrate) overspray by a spray lance 30 of the sliding layer material onto the end faces of the first and second bearing shells is reduced or eliminated.

In the second preferred embodiment of the present method described above, the sliding layer material is sprayed onto the whole of the inner surface of the substrates including the lining layer or, if present, the intermediate layer that is required), including over the first and second joint relief regions. As a result, a thickness of the sliding layer material is substantially constant (subject to the normal fluctuations in the thickness of the sliding layer) over the entire inner surface of the substrate of the first and second bearing shells, including over the first and second joint relief regions.

The earlier method is also generally suitable for manufacturing the first and/or second bearing shells forming bearing elements according to the second preferred embodiment of the present invention, but requires some modification as will now be discussed.

Unlike in the modified version of the earlier method described above for manufacturing bearing shells forming bearing elements according to the first preferred embodiment of the present invention, when manufacturing bearing shells forming bearing elements according to the second preferred embodiment of the present invention, there is no requirement for any modification of the method to include removal of material from the substrate (or optional lining layer or intermediate layer). Instead, prior to step D of the earlier method (i.e. assembling of a plurality of substrates for application of the sliding layer material) a mask is positioned on the surface of the bearing shells so that when the sliding layer material is applied in step G to the column of on the surface of the bearing shells, a portion of the sliding layer is applied to the mask as opposed to the running surface of the bearing shells. At an appropriate point in the method (at some point after step G), the mask is then removed to expose a portion of the layer beneath the sliding layer and provide the required joint face relief portions. Manufacturing methods based around masking of the bearing elements will be known to the skilled person and so the method will not be further described.

-18 -

Claims

CLAIMS1. A bearing element, comprising: a first bearing shell comprising a first substrate and a first sliding layer; a second bearing shell comprising a second substrate and a second sliding layer; wherein the first bearing shell comprises at a first end, a first joint face relief portion; wherein the second bearing shell comprises at a second end, a second joint face relief portion; wherein the first bearing shell and the second bearing shell are arranged so that the first end of the first bearing shell is proximate the first end of the second bearing shell and the second end of the first bearing shell is proximate the second end of the second bearing shell, the first and second bearing shells forming a bore for receiving a rotatable member; wherein the first and the second joint relief portions are positioned at leading edges of the respective first end of the first bearing shell and the second end of the second bearing shell relative to an intended direction of rotation of a rotatable member positioned within the bore; and wherein each of the first and second joint relief portions forms an undercut portion.
2. A bearing element according to Claim 1, wherein a depth of relief of each undercut portion is sufficient to accommodate offset shift between the first and second bearing shells and still provide a residual undercut portion.
3. A bearing element according to Claim 1 or 2, wherein a depth of relief of the first joint face relief portion is substantially equal to an average thickness of the first sliding layer and a depth of relief of the second joint face relief portion is substantially equal to an average thickness of the second sliding layer.
4. A bearing element, comprising: a first bearing shell comprising a first substrate and a first sliding layer; a second bearing shell comprising a second substrate and a second sliding layer; wherein the first bearing shell comprises at a first end, a first joint face relief portion; wherein the second bearing shell comprises at a second end, a second joint face relief portion; wherein the first bearing shell and the second bearing shell are arranged so that the first end of the first bearing shell is proximate the first end of the second bearing shell and the second end of the first bearing shell is proximate the second end of the second bearing shell, the first and second bearing shells forming a bore for receiving a rotatable member; -19 -wherein the first and the second joint relief portions are positioned at leading edges of the respective first end of the first bearing shell and the second end of the second bearing shell relative to an intended direction of rotation of a rotatable member positioned within the bore; and wherein a depth of relief of at least one of the first and second joint face relief portions is substantially equal to a thickness of the respective first and second sliding layer.
5. A bearing element according to any of the preceding Claims, wherein a depth of relief of at least one of the first and second joint face relief portions is greater than a thickness of the respective first and second sliding layer.
6. A bearing element according to any of Claims 1 to 5, wherein an average thickness of each of the first and second sliding layers is between about 3pm and about 25pm.
7. A bearing element according to any of Claims 1 to 5, wherein an average thickness of each of the first and second sliding layers is between about 5pm and about 15pm.
8. A bearing element according to any of Claims 1 to 5, wherein an average thickness of the each of the first and second sliding layers is between about 6pm and about 12pm.
9. A bearing element according to any of Claims 1 to 5, wherein an average thickness of the each of the first and second sliding layers is between about 7pm and about 11pm.
10. A bearing element according to any of Claims 1 to 5, wherein a depth of relief of each of the first and the second joint face relief portions is between about 5pm and about 7pm.
11. A bearing element according to any of Claims 1 to 5, wherein a depth of relief of each of the first and the second joint face relief portions is between about 8pm and about 10pm.
12. A bearing element according to any of the preceding Claims, wherein at least one of the first and second joint relief portions is formed by removal of material from the respective first or second substrate.
13. A bearing element according to Claim 12, wherein at least one of the first and second joint relief portions is formed by removal of material from a lining layer applied to the respective first or second substrate.
14. A bearing element according to any Claims 1 to 11, wherein at least one of the first and second joint relief portions is formed by masking the respective first and second bearing shell.
15. A method of assembling a bearing element for application of a sliding layer, comprising the steps of: providing a first bearing shell comprising at a first end a first joint face relief portion; providing a second bearing shell comprising at a second end a second joint face relief portion; and -20 -positioning the first bearing shell and the second bearing shell so that the joint faces of the first and second bearing shells are substantially aligned and the respective first and second joint face relief portions are proximate one another.
16. A method of applying a sliding layer material to a plurality of bearing elements comprising the steps of: providing a plurality of first bearing shells, each first bearing shell comprising at a first end a first joint face relief portion; providing a plurality of second bearing shells, each second bearing shell comprising at a second end a second joint face relief portion; positioning the plurality of first bearing shells adjacent the plurality of second bearing shells so that each first bearing shell is aligned with a second bearing shell forming a column of bearing shells having a hollow core and so that the respective first and second joint face relief portions of each first and second bearing shell are aligned.
17. A method according to Claim 16, in which the sliding layer material is sprayed or printed onto the column of bearing shells.
18. A method according to Claim 17, in which the sliding layer material is sprayed onto the column of bearing shells by a spray lance which is rotated relative to, and advance linearly along, the column of bearing shells.
19. A method according to Claim 18, wherein the spray lance is angled at between about and about 70 degrees to the normal to the column of bearing shells.
20. A method according to Claim 18, wherein a spray cone produced by the spray lance is divided equally by the normal to the surface of the column of bearing shells.
21. A method according to any of Claims 18 to 20, wherein the rotating spray lance is advanced linearly along the column of bearing shells at variable linear velocity.
22. A method according to any of Claims 18 to 21, further comprising the step of indexing the column of bearing shells between at least two passes of the spray lance along the column of bearing shells.
23. A bearing element manufactured by the method of any of Claims 16 to 22.
24. A bearing element substantially as hereinbefore described with reference to the accompanying drawings.
25. A method of assembling a bearing element for application of a sliding layer substantially as hereinbefore described with reference to the accompanying drawings.
26. A method of method of applying a sliding layer material to a plurality of bearing elements substantially as hereinbefore described with reference to the accompanying drawings.

-21 -
27. A method of manufacturing a bearing element substantially as hereinbefore described with reference to the accompanying drawings.
28. An internal combustion engine comprising a bearing element according to any of Claims 1 to 14 or Claim 23 or 24.-22 -