Abstract:
A flanged half-bearing includes at least one substantially semi-annular thrust washer with an internal periphery having lateral lugs and an intermediary stabilization lug projecting from the internal periphery of the thrust washer, and a semi-cylindrical half journal bearing shell having lateral recesses and an intermediary stabilization recess that are recessed into an axial end face of the bearing shell and are respectively connected to the lateral lugs and the stabilization lug of the thrust washer, wherein the stabilization lug has rotational stabilization edges that project substantially perpendicularly from the inner periphery of the thrust washer, and the stabilization recess is configured for axial relative movement of stabilization lug. An engine includes at least one such flanged half-bearing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of PCT/EP2012/004631 filed on Nov. 7, 2012, which claims priority under 35 U.S.C. §119 of Great Britain Application No. 1119174.9 filed on Nov. 7, 2011, the disclosures of which are incorporated by reference. The international application under PCT article 21(2) was published in English. 
     The present invention relates to a flanged half-bearing having a semi-cylindrical journal bearing shell and at least one semi-annular thrust washer, and particularly to a flanged half-bearing for an internal combustion engine. 
     BACKGROUND 
     The level of relative movement between a semi-annular thrust washer (also known as a thrust flange) and the semi-cylindrical journal bearing shell to which it is connected is of great importance, with respect to providing greater uniformity of wear within a bearing assembly, and ensuring correct assembly. 
     It is known to machine the bearing shells and washers of half-bearings in a single piece construction. Commonly, it is also known to firmly connect thrust washers to a bearing shell. For example, it is known to firmly and permanently connect thrust washers to a bearing shell by inserting lugs that are located on the inner periphery of the thrust washer into open-ended recesses in the axial end faces of the bearing shell, before mechanically deforming the bearing shell adjacent to the recesses to trap the lug within a dovetail connection. Such a flanged half-bearing is disclosed in GB2225392. It is also known to form such firm connections by use of tightly fitting dovetail shaped connections. 
     In use, flanged half-bearings are located within a housing, such as an engine block. Disadvantageously, a rigid connection between the thrust washers and the bearing shell can lead to unwanted gaps between the thrust washers and the housing. Such gaps can result in regions of unsupported load that could result in flexure and fatigue of the washers. 
     Furthermore, a rigid connection between the thrust washers and the bearing shell can result in a reduced contact area between the thrust washers and the housing, which provides poor heat transfer between the thrust washers and the housing, and may result in overheating of the thrust washers, leading to a reduction in the viscosity of the lubricating oil. A reduced oil viscosity leads to a reduction in the oil film thickness, resulting in increased wear of the bearing shell and the thrust washer. 
     Further, in the case that the connection is made by mechanical deformation of the bearing shell, this causes swelling of the surrounding material. In such cases it is typically necessary to perform a post-connection machining stage to remove the material swell that projects from the cylindrical inner surface of the bearing shell, which increases costs and prevents the use of performance enhancing coatings on the inner surface of the bearing shell. 
     It is also known to connect thrust washers to a bearing shell with hooking lugs projecting from and close to the ends of the internal periphery of the thrust washer, which loosely connect within open-ended hooking recesses in the axial end faces of the bearing shell. The bearing is assembled by elastically reducing the radius of curvature of the bearing shell before aligning with the thrust washers, such that the bearing shell radially expands back into shape, when released, and is loosely retained on the thrust washer. Such a bearing is disclosed in U.S. Pat. No. 4,533,261. 
     Disadvantageously, such a thrust washer is not connected to the bearing shell circumferentially intermediate the two hooking lugs and, in use, can experience a level of relative axial movement in that region that causes enhanced wear. Further, the design of hooking lug that is particularly favourable for the purposes of assembly provides only a limited amount of resistance against rotation of the thrust washer about the axis of the crankshaft, within the housing, which is particularly damaging. Additionally, such thrust washers can be vulnerable to incorrect assembly, potentially including damage occurring during the incorrect assembly, both of which can further enhance wear during use. 
     SUMMARY OF THE DISCLOSURE 
     According to a first aspect, there is provided a flanged half-bearing comprising
         at least one substantially semi-annular thrust washer with an internal periphery having lateral lugs and an intermediary stabilisation lug projecting from the internal periphery of the thrust washer, and   a semi-cylindrical half journal bearing shell having lateral recesses and an intermediary stabilisation recess that are recessed into an axial end face of the bearing shell and are respectively connected to the lateral lugs and the stabilisation lug of the thrust washer, wherein   the stabilisation lug has rotational stabilisation edges that project substantially perpendicularly from the inner periphery of the thrust washer, and the stabilisation recess is configured for axial relative movement of stabilisation lug.       

     According to a second aspect, there is provided an engine comprising at least one flanged half-bearing comprising
         at least one substantially semi-annular thrust washer with an internal periphery having lateral lugs and an intermediary stabilisation lug projecting from the internal periphery of the thrust washer, and   a semi-cylindrical half journal bearing shell having lateral recesses and an intermediary stabilisation recess that are recessed into an axial end face of the bearing shell and are respectively connected to the lateral lugs and the stabilisation lug of the thrust washer, wherein   the stabilisation lug has rotational stabilisation edges that project substantially perpendicularly from the inner periphery of the thrust washer, and the stabilisation recess is configured for axial relative movement of stabilisation lug.       

     The lateral lugs may be lateral hooking lugs and the lateral recesses may be lateral hooking recesses, which are configured to interconnect by hooking together. 
     The hooking lugs each may have mutually facing latching edges that converge towards the opening between the ends of the inner periphery of the thrust washer. 
     The hooking recesses each may have side edges remote from the circumferential ends of the thrust bearing configured such that they have a smaller circumferential separation adjacent the inner periphery of the thrust washer. 
     The stabilisation recess may have side edges that extend perpendicular to the axial end face of the bearing shell. 
     The stabilisation recess may be a generally rectangular recess. 
     The stabilisation recess may have a greater axial length than the axial thickness of the stabilisation lug. 
     The stabilisation lug may be located midway between the ends of the thrust washer, along the inner periphery of the thrust washer. 
     The stabilisation lug may be asymmetrically located along the inner periphery of the thrust washer with respect to ends of the thrust washer. 
     A plurality of stabilisation lugs may be provided circumferentially between the lateral lugs and projecting from the internal periphery of the thrust washer, and a corresponding plurality of stabilisation recesses may be provided in the axial end face of the bearing shell. 
     The centres of one or more of the plurality of stabilisation lugs and corresponding stabilisation recesses may be spaced apart from the crown by an angle of no more than 45°, preferably no more than 30°, more preferably no more than 20°, and most preferably no more than 10°. The one or more stabilisation lugs and corresponding stabilisation recesses are spaced apart from the lateral lugs provided proximate the ends (i.e. the substantially radial joint faces) of the thrust washer and the lateral recesses provided proximate the joint faces of the bearing shell. Accordingly, axial movement of the crown of the thrust washer relative to the bearing shell is permitted but limited, by the provision of these one or more stabilisation lugs and corresponding stabilisation recesses. 
     The plurality of stabilisation lugs and stabilisation recesses may be asymmetrically arranged located along the inner periphery of the thrust washer with respect to ends of the thrust washer. 
     The flanged half-bearing may comprise two thrust washers connected to opposed axial ends of the bearing shell. 
     The thrust washer may have a main body section and the stabilisation lug projects out of coplanar alignment with the main body section. 
     The stabilisation lug may diverge away from the plane of the main body section along its length. 
     The stabilisation lug may have a terminal portion that is parallel and perpendicularly displaced from the plane of the main body section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: 
         FIGS. 1A to 1F  illustrate a substantially semi-annular thrust washer; 
         FIGS. 2A to 2E  illustrate a semi-cylindrical half journal bearing shell; 
         FIGS. 3A to 3C  illustrate a flanged half-bearing; 
         FIGS. 4A to 4C  illustrate alternative stabilisation lugs of the thrust washer; and 
         FIG. 5  illustrates a further substantially semi-annular thrust washer. 
     
    
    
     DETAILED DESCRIPTION 
     Like numbers refer to like elements throughout. 
       FIGS. 1A to 1F ,  FIGS. 2A to 2E  and  FIGS. 3A to 3C  illustrate a flanged half-bearing and its component parts according to an embodiment. 
       FIG. 1A  illustrates an axial view of a substantially semi-annular thrust washer  100  having a generally semi-annular main body portion  102  with hooking lugs  104 A and  104 B and a stabilisation lug  106  projecting from the inner periphery  108 . The hooking lugs  104 A and  104 B have latching edges  110  that face generally towards the opposite ends  112  of the thrust washer  100 , as is shown further in the enlarged view of  FIG. 1B , corresponding with circle D of  FIG. 1A .  FIG. 1C  shows an axially cross-sectional view through the thrust washer  100  at the hooking lug  104 A, illustrating that in the first embodiment the lug is thinner than the main body  102  of the thrust washer, to facilitate hooking to a hooked recess in a bearing shell. 
       FIG. 1D  illustrates an enlarged view of the stabilisation lug  106 , corresponding with the circle E in  FIG. 1A . The stabilisation lug  106  has rotational stabilisation edges  114  that project substantially perpendicularly from the inner periphery  108  of the thrust washer  100 . 
     The stabilisation lug  106  has a circumferential width (around the inner periphery  108  of the thrust washer  100 ) of 2.0 to 10.0.0 mm (e.g. 3.67 to 6.22 mm), a thickness (parallel to the axis of the crankshaft) of 0.5 to 5.0 mm (e.g. 2.36 to 3.43 mm) (the main body portion  102  may also have a corresponding thickness of 0.5 to 5.0 mm), and a radial extension from the inner periphery of the thrust washer  100  of 1.0 to 5.0 mm (e.g. 1.8 to 3.1 mm). The stabilisation lug  106  is thinner than the main body portion  102  of the thrust washer  100 . However, the stabilisation lug may alternatively be of the same thickness as the main body portion. In the illustrated embodiment, the stabilisation lug  106  is asymmetrically offset from the centre of the thrust washer  100  (i.e. from the mid-point of the inner periphery  108 , between the ends  112 ) by 0.7 mm. 
       FIG. 1F  illustrates a sectional view of thrust washer  100  along the plane indicated by line A-A in  FIG. 1A . The thrust washer  100  may be manufactured by stamping, machine or cutting from a sheet material, with the thickness profiles of the lugs  104 A,  104 B and  106  being machined by an axially located cutter. 
       FIG. 2A  shows a view of a semi-cylindrical half journal bearing shell  220  from the concave, inner surface  222 , and  FIG. 2B  shows an axial side view of the bearing shell. The bearing shell  220  has axial end faces  224 A and  224 B, each of which has lateral hooking recesses  226 A and  226 B close to the joint faces  227  and a stabilisation recess  228 . The bearing shell  220  is additionally provided with a circumferential groove  232  along the concave, inner surface  222 , with an oil supply hole  234  through the thickness of the bearing shell.  FIG. 2C  shows an enlarged view of the central portion of the bearing shell  220 , more clearly showing the rectangular shape of the recesses  228 , which have parallel side edges  230  that run axially, perpendicular to the axial end faces  224 A and  224 B. 
     The stabilisation recess  228  is dimensioned in correspondence with the stabilisation lug  106  and the thickness of the thrust washer main body  102 . The stabilisation recess  228  has a circumferential width (i.e. around the axial faces  224 A and  224 B) greater than the circumferential width of the stabilisation lug  106  by a total clearance of about 1 mm. The axial depth of the stabilisation recess is preferably greater than or equal to the axial thickness of the stabilisation lug  106 , and may be about the same thickness as the main body  102  of the thrust washer  100 . The stabilisation recess  228  is offset from the middle of the axial end of the bearing shell  220  in correspondence with the offset of the stabilisation lug  106  on the thrust washer  100 . One of the side edges  230  is provided at the middle of the axial end of the bearing shell  220 . 
       FIGS. 2D and 2E  show enlarged views of the recess  226 B, showing the hooking side edge  234 , which is angled non-perpendicularly to the axial end face  224 A, such that when a hooking lug  104 A and  104 B is connected within the recess, it is prevented from exiting the recess in an axial direction. 
     It will be appreciated that not all half-bearings may be provided with the groove  232  and/or the oil supply hole  234 . In particular, when two half-bearings are used together, one may have such a groove and oil supply hole, and the other may not. Further, both half-bearings may be of the type described herein, or one may be such a half-bearing and the other may be a half-bearing of a known design. 
       FIGS. 3A ,  3 B and  3 C show views of an assembled flanged half-bearing  330  comprising a pair of semi-annular thrust washers  100 A and  100 B and a semi-cylindrical half journal bearing shell  220 , which are connected together by the hooking lugs  104 A and  104 B being hooked within the hooking recesses  226 A and  226 B, and having the stabilisation lugs  106  received into the stabilisation recesses  228 . 
     The half-bearing  330  is assembled by elastically bending the bearing shell  220  to a smaller radius of curvature, aligning with respect to the thrust washers  100 A and  100 B, and then releasing the bearing shell, so that it radially expands to engage the lugs  104 A,  104 B and  106  within the recesses  226 A,  226 B and  228 . Accordingly, the thrust washers  100 A and  100 B become engaged upon the bearing shell  220 , in a hooked manner. In particular, the latching edges  110  converge towards the opening between ends of the thrust washer  100 , which prevents the engaged lugs  104 A and  104 B from exiting the recesses  226 A and  226 B perpendicular to the axis of the bearing. The angle of convergence may be between 40 and 50°. 
     Whilst permitting a small amount of relative axial play, the projection of the stabilisation lug  106  into the stabilisation recess  228  interlocks the thrust washer  100  with the bearing shell  220 . This prevents substantial relative axial movement of the crown of the washer  100  and bearing shell  220 . Further, the engagement of the rotational stabilisation edges  114  of the stabilisation lug  106  within the recesses  228 , between the parallel side edges  230  of the recesses  228 , prevents substantial relative rotational movement of the thrust washer(s)  100  and the bearing shell  220 , with respect to the axis of the half-bearing  330 , whilst again allowing a small amount of relative rotational play. Preventing substantive relative rotation about the axis of the bearing half-bearing  330  reduces the load and wear experienced by the hooking lugs  104 A and  104 B. 
       FIGS. 4A ,  4 B and  4 C illustrate alternative stabilisation lugs  406 ′,  406 ″ and  406 ′″. The lug  406 ′ of  FIG. 4A  is of equal thickness to the main body  402  of the thrust washer, without being thinned, in contrast to the lug  106  of  FIG. 1E . In the formation of such a thrust washer, an axially located, cammed cutter may be used to machine the hooking lugs  104 A and  104 B, without machining the stabilisation lug  406 ′. Such a lug  406 ′ provides enhanced resistance both to axial relative movement of the thrust washer and the bearing shell, and also is stronger, thereby better preventing rotational relative movement. 
     Alternatively, to avoid the requirement to use a cammed cutter when machining the hooking lugs  104 A and  104 B, the stabilisation lug  406 ″ and  406 ′″ may be bent out of alignment with the main body  402  of the thrust washer. In  FIG. 4B  the lug  406 ″ diverges from the plane of the main body  402 , whereas in  FIG. 4C  the lug  406 ′″ has a terminal portion  450  that is parallel with the main body  402 , but overset from the plane of the main body. With such a lug, the bearing shell will be provided with a stabilisation recess having a greater axial length. 
     Advantageously, the provision of the stabilisation lug and cooperating stabilisation recess permits a small amount of relative rotational play, whilst preventing substantial relative rotational movement of the thrust washer and bearings shell. Further, advantageously the stabilisation lug and cooperating stabilisation recess permit a restricted level of axial relative movement of the thrust washer and bearing shell at the crown of the half-bearing, which is greater than that of corresponding components that are firmly connected by mechanical deformation or a dovetail connection, yet smaller than the corresponding relative axial movement in the absence of a lug and recess at that location. In particular, the stabilisation lug and cooperating stabilisation recess permit axial movement of the crown of the thrust washer away from the bearing shell, whilst limiting axial movement of the crown of the thrust washer towards the bearing shell. 
       FIG. 1A  illustrates a stabilisation lug  106  that is closer to one end of  112 B than the other  112 A of the thrust washer  100 , i.e. the centre of the lug is spaced to one side of the crown of the thrust washer, which corresponds with the centre line  107 . Advantageously, provision of the stabilisation lug off-centre on the thrust washer (i.e. such that the thrust washer is not mirror symmetric, with respect to the location of the stabilisation lug) could prevent the thrust washer from being incorrectly connected to the bearing shell. However, alternatively, the stabilisation lug may be centrally located on the inner periphery of the thrust washer. 
     In a further embodiment the thrust washer may be provided with more than one stabilisation lug between the hooking lugs along the inner periphery, and the bearing shell may be provided with a corresponding number of stabilisation recesses in the axial end face(s).  FIG. 5  illustrates such a thrust washer  500 , which is provided with two stabilisation lugs  506 A and  506 B. The centres of the two stabilisation lugs  506 A and  506 B are each spaced apart from the crown (i.e. centre line  507 ) by an angle A of no more than 45° (preferably no more than 30°, more preferably no more than 20°, and yet more preferably no more than) 10°). The arrangement of the plurality of stabilisation lugs may be asymmetric with respect to the crown  507  and ends  512 A and  512 B of the thrust washer. 
     The figures provided herein are schematic and not to scale. 
     Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. 
     Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.