AU690213B2

AU690213B2 - Plain bearing

Info

Publication number: AU690213B2
Application number: AU16610/95A
Authority: AU
Inventors: Noel Francis Sheedy
Original assignee: Plastic Bearings and Housing Australasia Pty Ltd
Current assignee: Plastic Bearings and Housing Australasia Pty Ltd
Priority date: 1994-02-08
Filing date: 1995-02-08
Publication date: 1998-04-23
Anticipated expiration: 2015-02-08
Also published as: AU1661095A

Description

PLAIN BEARING The invention relates to bearings and bearing assemblies.

Conventional roller bearings consist of an inner race member, an outer race member and roller balls held between inner and outer races by a cage or flanges. Various types of plain bearings are also known in which rolling elements are replaced by a plastic bush. Some plain bearings of this type are able to operate without a lubricant however plain bearings generally suffer from the limitation that the bearing members became fused at high speed and/or under high loads.

Despite the improvements in plain bearings there is need for such a bearing which has a longer service life and/or is able to operate under more severe conditions such as high loads or at high speed for prolonged periods.

According to the present invention there is provided a plain bearing assembly comprising: 15 inner bearing means providing an annular peripheral bearing surface; outer bearing means coaxial with the inner bearing means and providing an inner annular bearing surface; and at least one set of intermediate bearing means coaxial with the inner bearing means and outer bearing means, each set of intermediate bearing means providing a bearing ring having an inner annular bearing surface, an outer annular bearing surface, and at least one radial surface and providing bearing ring bush means rotatably mounted abut the inner bearing means rotatable with respect to the bearing ring and the outer bearing means, the bearing ring bush means providing a bearing surface adjacent to the inner 25 annular bearing srface of the bearing ring, a bearing surface adjacent the outer annular bearing surface of the bearing ring, and an axial bearing surface adjacent to each of the radial surfaces of the bearing ring in a coaxial direction.

The intermediate bearing means of the bearing of the invention includes at least one bearing ring and bush means. The bush means may be in the form of a single bush member comprising two bush rings one inside and one outside of the bearing ring and connected by a web extending adjacent the end of the bearing ring. It is particularly preferred, however, that the bearing bush means la include an inner bush member rotatably mounted about the inner bearing means and rotatable with respect to the bearing ring and having a peripheral bearing surface adjacent the inner bearing surface of a bearing ring and an outer bearing bush e o WO 95/22011 PCT/AU9500058 2 rotatably mounted about the beating ring and having an inner bearing surface adjacent the outer bearing surface of the bearing ring, The bearing ring may be integrally formed with the inner or outer bearing means however it is preferred that it be rotatable with respect to each of the inner and outer bearing means, In a preferred form of the bearing of the invention one of the inner and outer bearing means includes an annular locating flange and an radial bearing surface disposed on each side of the locating flange and the other of said inner and outer bearing means includes a pair of collars one collar extending on each side of the flange and the bearing includes two sets of intermediate bearing means disposed between facing sides of the collars and locating flange one set on each side of the flange.

Preferably one of the collars, referred to a the thrust collar, is removable from the bearing means comprising the pair of collars such that the other bearing components may be removed and reassembled a is required. It is preferred the thrust collar is detachable from the race provided with a collar at one end of the race a bearing surface and a portion for receiving the thrust collar at the other end of the race. The portion for receiving the thrust collar may be recessed; the recessed portion being on the inner surface when the outer bearing means includes said collars and on the outer surface when the inner bearing means includes the collars. The thrust collar receiving portion may also be provided witha radial groove to allow the end of the thrust collar receiving portion to be deformed to retain the collar. Alternatively, the thrust collar and collar receiving portion may comprise corresponding threaded portions.

The locating flange, which is preferably present on the inner surface of outer bearing means, may be continuous or discontinuous and in the form of circumferentially spaced tabs or the like. The locating flange may be in a variety of sections or shapes such a square rectangular, curved, dovetailed, bevelled or WO 95/22011 PCT/AU95/00058 3 the like. Preferably the flange has essentially parallel sides and is disposed at right angles to the axis.

In this preferred form of the invention the intermediate bearing means are typically located each set in a recess or chamber defined between bearing surfaces of the inner or outer bearing means and the facing sides of each collar and the flange.

There may be two or more recesses separated by a locating flange projecting from either the first or second bearing means and two or more bush members and/or bearing rings may be located in each of the recesses. For example, two bearing rings may be coaxially arranged and separated from each other and from the inner bearing means by bushes.

The inner bearing means of the present invention most preferably includes an annular inner bearing surface and a pair of collars one at each end of the race.

The inner bearing means is preferably located within the outer bearing means such that the collars of the inner bearing means are in face to face relationship within an inwardly disposed flange on the outer bearing means. One of the collars is preferably a thrust collar adapted to be removably connected to the inner bearing means to enable an annular outer bearing means, annular bearing ring and bearing bushes to be removed from and assembled about the bearing surface of the inner bearing means.

The inner bearing means may include a bore for receiving a shaft or the like. The bore may be of any suitable shape for example it may be of circular, oval, triangular, square, hexagonal, rectangular or other configuration. Further, where the inner bearing means includes a bore the bore may be tapered between one and the other and may include a spline, gear teeth, it may be serrated or include other means for engaging a drive shaft or the like.

Where the inner bearing means includes a bore for receiving a shaft or the like the inner bearing means may be in the form of a sleeve and include axially extended portion which includes means for fixing the bearing to the shaft. The WO 95/22011 PCT/AU95/00058 4 axially extended portion may include one or more holes for receiving a grub screws or may be constrictable and be provided with constructor means adapted to urge the constrictable portion into locking engagement with the shaft.

The inner race portion of the inner bearing means means may be provided with a threaded portion to engage a correspondingly threaded thrust collar. In this form, the thrust collar may also include an additional annular flange having a bore corresponding to an inner race bore, and having a threaded radial aperture therethrough to receive a grub screw or the like. Alternatively, the thrust collar may be provided with means for engaging an annular eccentric collar having an aperture capable of receiving a grub screw or the like for fixing the bearing to a shaft located in the bore. In another alternative form, the inner bearing means comprises an extended portion in the form of an annular axial flange. This axial flange may also have an aperture therein suitable to receive a grub screw or the like, for securing the bearing to a shaft or the like.

The bush members and the bearing ring of the intermediate bearing means are typically are coaxial and preferably there are two coaxial sets of intermediate bearing means each set comprising at least one intermediate member and at least two bearing bushes and being located one series in each of two recesses defined by inner and outer bearing means.

It is preferred that the bearing ring is of smaller axial width than at least one and preferably two of the bearing bushes. Further, the Applicant has found that operation of the bearing is significantly improved where at least one of the bearing bushes in each set of intermediate bearing means includes one or more lips which cooperate with the bearing ring to retain the ring spaced apart from the facing sides of the flange and collar.

The bushes may have a lip adjacent one edge thereof and extending adjacent an edge of the bearing ring 'hereby preventing the bearing ring from directly engaging the inner or outer bearing members. Preferably each of the bearing WO 95/22011 PCTAU95/00058 bushes has a lip and the bearing bushes adjacent the inner and outer circumference of the bearing ring cooperate such that the respective lips are located adjacent opposing ends of the intermediate bearing ring.

In the most preferred embodiment one of the lips radiate from adjacent the side of the inner bearing bush and the other lip is internally disposed adjacent the opposite side of the outer bearing bush and the flanges coact to provide alignment of the ring and to provide axial bearing surfaces between the bearing ring and inner and outer bearing means. Radiating grooves circumferentially spaced on the outer face of the bush lips are also preferred and are believed to aid in heat dissipation and enhance the performance of the bearing.

The bearing of the present invention may be used as wheel bearings for any type of vehicle, such as motor cars, motor cycles, tractors, bicycles, and trucks or the like, and also tractors, bicycles, and trucks or the like, and also trailers of any type such as caravans, and boat or car trailers or the like. The bearing of the present invention may also be used directly as a wheel, as a surface levelling or finishing roller, or as any other form of a direct load carrying rolling member in a vehicle, agricultural implement or the like.

In another embodiment the bearing of the invention is in the form of a cam follower wherein the first bearing means comprises an inner race stud together with a thrust collar. The inner race stud may be similar to a conventional bc't, having a head, an axially adjacent locating shaft portion providing a peripheral bearing surface and a threaded shaft portion axially adjacent to the locating shaft.

The head if the bolt mnay define the inner race collar and the threaded shaft may receive a thrust collar which may include a cooperating thread in its inner circumference or the thrust collar may be secured by a threaded locking nut. The thrust collar may take the form of an annular washer or the like.

WO 95/22011 PCTIAU95100058 6 The bearing of the invention may further comprise a housing for receiving the outer bearing means such as a pillar block housing two or more hole flange housing.

It will also be understood by a person skilled in the art that the external surface of the outer bearing means may be of any cross-section. The surface may be cylindrical, convexly or concavely curved, tapered, conical or frustoconical, or any combinations of shapes, dependent upon specific requirements and intended use. For example, the bearing means may be substantially rectangular so that the bearing itself may be rigidly secured to another member as required.

The outer bearing means may have a convex outer surface particularly a spheral section to enable the outer bearing means to be received into a housing having a corresponding concave inner surface whereby the outer bearing means may pivot within the housing to allow it to align with a shaft or the like. Such a housing may be a pillar block housing, a 2- or more hole flange housing, a hanger type housing to allow the bearing to be used on a conveyor system for suspending articles from a conveyance line or may comprise sprockets or gears about its periphery.

The outer bearing means may also comprise protrusions such as sprockets gear teeth or tabs or the outer bearing means may have a peripheral annular groove to enable it to engage a belt or pulley. An outer bearing means including an outer surface having one or more V-shaped grooves may also be used.

The outer bearing means may include means for fixing the bearing for operation.

For example, where the bearing is to be used as a wheel hub it may include a radial flange with axial holes circumferentially spaced about the radial flange for fastening the bearing to a wheel. The outer bearing means may also be shaped to act as a pillar block housing, or a 2- or more hole flange housing or the like.

One or more of the inner bearing means, outer bearing means, bush members and bearing ring may be split radially to fomi two annular portions with abutting LI I I WO 95/22011 PCT/AU95/00058 7 faces or may be split axially to form abutting semicircular portions which together form the annular bearing component. The split components may include engaging portions such as corresponding protrusions and recesses or where the bearing is a self aligning bearing it may be preferred to use a split housing to enable portions of the housing to be assembled about the bearing. Alternatively a housing comprising a convex inner surface and a pair of diametrically opposed slots may be used to allow the bearirng to be inserted or removed from the housing when aligned with the slots and at right angles to the housing and to be pivoted within the housing to align with a shaft or the like.

In the bearing of the invention, the bearing bushes will, during operation, typically oscillate between a condition in which they are stationary with respect to the bearing surface of smaller circumference and rotate with respect to the bearing surface of greater circumference and a condition in which they are stationary with respect to the bearing surface of greater circumference and rotatable with respect to the bearing surface of smaller circumference.

This oscillating action during operation, particularly when at least two bushes are present one inside and one outside the bearing ring, significantly improve the operating life of the bearing and reduce wear of the bearing surfaces even a very high speeds and under light load.

The adjacent bearings surfaces of the bearing tof the invention are typically formed of different materials. Thus the bearing surface of the inner and outer bearing means and bearing ring may be formed of one material while the bearing surfaces of the bushes are formed of a different material. It is therefore particularly preferred in order to provide a long service life and the most effective performance that the bearing bush means be constructed of a different material to the inner and outer bearing means and the bearing ring. Preferably one of the group of components selected from a first group consisting of the inner bearing means the outer bearing means and the bearing ring and a second group of consisting of the bearing bushes are formed of a plastics material and the outer WO 95/22011 PCT/AU95/00058 8 of said first and second group of components is formed of metal. Most preferably each of the inner bearing means, outer bearing means and bearing ring is formed of metal and the bearing >,ushes are formed of plastics material.

The bush members of the present invention are preferably fabricated from a thermoplastic polyester resin and the inner and outer bearing means are preferably made from a corrosion proof metal such as stainless steel, aluminium or the like (although other metals may be used) may be coated with a hard material such as a titanium nitride or ceramic coating or the like. Additionally, all of the components may be made of plastics material, for example, the outer bearing means, the bearing ring and the inner bearing means may be of one plastics composition while the bearing bushes are of a different plastics material.

However, the outer and inner bearing means and bearing ring may be made of synthetic polymeric material, and the bush members may be made from a corrosion proof metal or other metals which may be coated as above.

The bush members may be fabricated or moulded from a synthetic polymeric material or materials, such as PTFE, CTFE, PEEK, ACETAL, polyimide, poly(amide/imide) unreinforced or a partially crystalline, thermoplastic polyester, for example polyethylene terephthalate. Materials from which the components of the present invention may be made include plastics, ceramics, glass, pure carbons, carbon fibres, graphite impregnated materials, kevlar, phosphorous bronze or the like and may include combinations thereof. It will be understood by a person skilled in the art that the selection of the optimum material will be dependent upon the particular application required of the bearing. For instance, where the bearing is being used in a corrosive atmosphere due to the presence of a particular type of chemical, a material would be selected that was resistant to that type of corrosion. Similarly, if metals are used in the bearing, then the same considerations would apply. For instance, if rusting was not perceived to be a problem, mild steel may be used. Alternatively, 316 stainless steel may be used, or, 4.10 stainless steel may be used. Aluminium may also be used and the metals may be impregnated with a polymer such as PTFE.

WO 95/22011 PCT/AU95/00058 9 As hereinbefore described the inner bearing means may be included a sleeve adapted to receive a shaft and the sleeve may be provided with means for.fixing the bearing to a shaft.

We have found that alignment of the bearing and performance of the bearing on a shaft may be enhanced if the sleeve has a constrictable portion.

In a further aspect the invention provides a bearing for a shaft comprising an inner bearing means including a sleeve for receiving the shaft and having an annular peripheral bearing surface and an outer bearing means rotatably having an inner bearing surface mounted about the sleeve wherein the sleeve comprises an annular constrictable portion and constrictor means for providing annular constriction to force the constrictable portion into locking engagement with the shaft.

The annularly constrictable portion preferably comprises a series of slots circumferentially spaced about the sleeve and generally aligned with the axis on the sleeve so that the portions of the sleeve between the slots are radially inwardly deformable in response to a constriction force from the constrictor means.

The constrictor means typically comprises a bore adapted to be received on the sleeve and the sleeve and constrictor means preferably comprise corresponding engaging mans, such as threaded portions, to urge the constrictor means along the sleeve so that the inner circumference of the constrictor means impinges upon the constructible portion of the sleeve to cause constriction thereof. The constrictor means is preferably a nut or threaded collar.

In a particularly preferred embodiment the sleeve of the bearing extends beyond the race and the annularly constrictable portion is located adjacent a protruding end of the sleeve. In this embodiment it is preferred that the slots extend from the ~r WO 95/22011 PCT/AU95/00058 end of the sleeve in alignment with its axis and are circumferentially spaced to form a multiplicity of radially inwardly deformable segments. The constrictor means is receivable on the slotted end of the sleeve and the inner circumference of the constrictor means provides an inward force to the segments as it is urged along the sleeve to thereby lock the sleeve onto a shaft. The constrictable portion of the sleeve preferably has an outer surface inwardly tapering toward the slotted end of the sleeve and the constrictor means is adapted to be received onto and cooperate with the sleeve to impinge upon the tapered portion of the sleeve to force the con,'7ictable portion inward. Alternatively or in addition to the tapering of the constrictable portion the inner surface of the constrictor means may inwardly taper to provide a constricting force to the constrictable portion of the sleeve as it is urged onto the sleeve. The constricting force may alternatively be provided by a flange on the inner surface of an annular constrictor means.

Preferably the sleeve and constrictor means comprise threaded portions which cooperate such that relative ratation of the cooperating threaded portions urges the annular constrictor means along the sleeve and against the tapered surface of the constrictable portion.

The slotted end of the annular constrictable portion may narrowingly taper and be threaded so that the constriction means impinges upon the tapered sides of the constrictable portion during relative rotation of the constriction means and constrictable portion during relative ratation of the constriction means and constrictable portion. Alternatively the sieeve may be threaded between the slotted constrictable portion and the bearing race and the annular constriction means may comprise a threaded portion and a portion which impinges upon the tapered constrictable portion.

The constrictable sleeve is particularly useful in bearings including intermediate bearing means. The sleeve and intermediate being means of the invention may comprise an annular flange and mutually abutting rings respectively as described in US patent 5,219,231. The sleeve comprises an annular flange and the outer WO 95122011 PCTIAU95100058 11 being means comprises a pair of mutually abutting rings which together define a recess for receiving the annular flange to allow relative rotation between the race and sleeve and wherein the mutually abutting surfaces of the rings include an annular flange axially extending from one of said rings and a recess in the other ring, said axially extending flange and correspnnding recess cooperating to retain mutual alignment of the rings.

The constrictable portion is preferably resilient so that the sleeve is movable on the shaft when the locking force of the constrictor means is removed.

Some examples of practical arrangements of the invention will now be described with reference to the accompanying drawings. However, it is to be understood that the following description in no way limits the generality of the invention as described above.

In the drawings: Figure 1 is a part cross sectional view of a bearing of the invention.

Figure 2 is a partial perspective view of the components of the bearing of Figure 1.

Figures 3a to 3e are partial perspective views of alternative constructions of the inner bearing means of Figure 1.

Figure 4 is a further embodiment of the bearing of the invention.

Figure 5a is a part cross section view of an alternative outer bearing means of the bearing of figure 1.

JL jMrj"'r WO 95/22011 PCT/AV95/00058 12 Figure 5b shows a part cross section view of a further e ,ple of an alternative outer bearing means for the bearing of the Figure 1.

Figure 5c is an inside perspective view of an alternative thrust collar of the bearing of Figure 1.

Figure 5d is an axial cross section of a further embodiment of an outer bearing means and intermediate bearing means of the invention.

Figure 5e is an axial cross section of a further embodiment of an inner bearing means and intermediate bearing means of the invention.

Figure 6a is a partial perspective views of an inner bearing means of the invention which include means for fixing the bearing to a shaft.

Figure 6b is a cross section of the inner bearing means of Figure 6a which is locked into a shaft.

Figure 6c is partial perspective view )f an inner bearing means.

Figure 6d is a cross section view of the inner bearing means of Figure 6c which is locked into a shaft.

Figure 6e and 6f show a further embodiment of a lockable inner bearing means in position in which it is movable (6e) and locked into a shaft.

Figures 7a to 7c show cross sections of alternative inner bearing means for the bearing of the invention Figures 8a to 8g show the cross section of alternative shapes of outer circumference portion of the outer bearing means of the bearing of the invention.

WO 95122011 PCT/AU95/0oo058 13 Figure 8h shows an outline of the bearing of the invention in the form of a cam, Figure 10a to 1Of are perspective view of housings within which embodiments of the bearing of the invention may be received.

Illustrated in Figures 1 and 2 are components of the bearing shown assembled in Figure 1 and with the components separated in Figure 2.

Illustrated is an inner annular bearing means in the form of a sleeve for receiving a shaft and having a peripheral bearing surface which forms the annular inner race. The inner bearing means further comprises a pair of shoulders or collars and One of the collars is fixed adjacent the bearing surface and the other collar referred to as a thrust collar, may be removed to allow assembly and disassembly of the bearing and is received upon an annular recessed portion of the inner bearing means on the side of the bearing surface remote from the fixed collar The outer bearing means is an outer race having an inwardly disposed locating flange which separates two inner radial bearing surfaces on the outer bearing means. The flange has parallel sides which, when the bearing is assembled, are in face to face relationship with the inside sides of collars The inner bearing surface and collars of the inner bearing means (1) together with the outer bearing surface and sides of the inwardly disposed flange on the outer bearing means define two annular chambers or recesses.

In each of the recesses there is located a set of intermediate bearing members including a bearing ring (10) having bearing surfaces (11,12) on its inner circumference (11) and its outer circumference an inner bearing bush (13) having bearing surfaces (14,15)on its inner circumference (14) and outer circumference (15) disposed between the bearing ring (10) and the bearing surface of the inner bearing means and an outer bearing bush (16) having bearing surfaces (17,18) on its inner circumference (17) and its outer circumference (18) located between the bearing ring (10) and the bearing surface I II 14 of the outer bearing means The inner bearing means outer bearing means and bearing ring (10) are formed of a metal such as aluminium which may be impregnated with a plastic coating such as PTFE. The bearing bushes (13,16) are formed of a plastics material such as a polyimide.

The inner bearing surface (14) of the inner bearing bush is disposed adjacent the bearing surface of the inner bearing means The bearing ring (10) inner and outer bearing surfaces (11,12) lie adjacent the outer surface (15) of the inner bush member and the inner bearing surface (17) of the outer bearing bush (16) respectively. The outer bearing surface (18) of the outer bush (16) lies adjacent and is rotatable with respect to the bearing surface of the outer bearing means Although each of the annular bearing components 6, 9, 13, 16) is rotatable with respect to any other of the annular bearing components 6, 9, 13, 16) rotation of the inner bearing means with respect to the outer bearing 15 means(6) has been found to cause the bushes to oscillate between a condition in which they are stationary with respect to the adjacent bearing surface of smaller "I circumference and rotatable with respect to the bearing surface of greater :conference and a condition in which the bearing bush is stationary with respect to the adjacent bearing surface of greater circumference and rotatable with respect 20 to the adjacent bearing surface of smaller circumference. In particular during operation the inner bearing bush (13) (in each recess) in operation oscillates between a condition in which it is stationary with respect to the inner bearing means.(1) and rotatable with respect to the intermediate bearing ring (10) and rotatable with respect to the inner bearing means The outer bearing bush (16) oscillates between a condition in which it is stationary with respect to the intermediate bearing ring (10) and rotatable with respect to the outer bearing means and condition in which it is stationery with respect to the outer bearing means and rotatable with respect to the intermediate bearing ring As a result the bushes appear to float between these conditions and the bearing ring also floats, rotating intermittently under the influence of either the inner or outer bearing means.

WO 95/22011 PCT/AU95/00058 Each of the bearing bushes (13 and 16) has a lip (19,20) adjacent on edge thereof. The lips (19, 20) of the inner and outer bearing bushes (13, 16) are disposed each adjacent opposite ends of the intermediate bearing ring (10) so that they retain alignment with the intermediate bearing ring (10) and prevent the intermediate bearing ring (10) from directly engaging the first or second bearing members by providing an axial bearing surface between ends of the bearing ring (10) and the facing sides of the locating flange and collar (3 or The lip (19,20) in each bearing bush (13,16) has circumferentially spaced radiating grooves (21) on its outer face. The grooves reduce the effects of friction and assist in dissipation of heat during operation. Grooves may also be provided on the other end of each bush.

The bearing of the invention may be assembled by placing one set of intermediate bearing means on the bearing surface of the inner bearing means such that the lip (19) of the inner bush (13) is adjacent the inner side of the fixed collar The outer bearing means may then be located about the bearing surface of the inner bearing means and the intermediate bearing means such that the lip (20) of the outer bush (16) is adjacent the side of the flange facing the collar The second set of intermediate bearing means (9) is mounted between the bearing surfaces so that lip (20) if the outer bush is adjacent the flange and the thrust collar is fastened onto the recessed end adjacent the bearing surface so that its inner side is adjacent the lip (19) of the outer bush (13).

The intermediate bearing means retain spacing between the inner and outer bearing means The outer bearing means extends about the collars (3,4) and ring end flush with the outside of the collar. The intermediate bearing means retain spacing between the outer bearing means and periphery of the collars and the outer bush (16) may extend between the outer bearing means and periphery of the collars to provide a seal between inner and outer bearing means I WO 95/22011 PCT/AU95/00058 16 The inner circumference of the flange is also spaced from the bearing surface of the inner bearing means by intermediate bearing means The outer peripheral surface of the outer bearing means may be provided with means for fixing a bearing. In Figure 1 the outer bearing member comprises a radial fixing flange (23) on it outer circumference Circumferentially spaced holes (23a) are located about the fixing flange 23 which allow the bearing to be fixed to a wheel so it is used as the bearing hub of the wheel.

Referring to Figures 3a to 3e the inner bearing means of the invention may include means for attaching the thrust collar to a shaft. The inner bearing means is provided with an annular recess adjacent one end. The thrust collar (4) is annular and its inner circumference is receivable on the recessed portion of the inner bearing means(l) to thereby provide two collars spaced at either end of the inner bearing surface between which collars the intermediate bearing means and locating flange of an outer bearing means are received.

As shown in Figure 3a the means for attaching the thrust collar may be by an inner annular groove (24) about the recessed portion to allow the end of the recessed portion to be deformed or flared over the outer face of the thrust collar The outer face of the thrust collar may have a chamber (25) adjacent the inner edge of the outer side wall to facilitate flaring of the end of the recess portion The inner bearing means further includes an extended axial portion (26) provided with a radial hole for receiving a grub screw to enable the inner bearing means to be removably fixed onto a shaft.

Figure 3b shows an inner bearing means in the form of an inner race stud.

The inner bearing means has a solid shaft provided with a collar at one end, a peripheral bearing surface adjacent and a recessed portion for WO 95/22011 PCTIAU95/00058 17 receiving the thrust collar adjacent the other end of the bearing surface The recessed portion is threaded (29) for receiving a nut which may retain the thrust collar adjacent the bearing surface Alternatively the collar itself may be threaded on its inner circumference to engage and allow it to be fastened on the threaded recessed portion (29).

Figure 3(c) and 3(d) shows an inner bearing means in the form of a sleeve for receiving a shaft and the recessed portion and inner circumference of the thrust collar have cooperating threaded portions so that the collar may be fastened on the recessed portion adjacent the bearing surface The thrust collar is provided with an additional annular flange (30) on its outer side and the flange has a smaller inner circumference than the threaded portion of the collar so that it lies adjacent one end of the inner bearing means sleeve (32) when the collar is fastened into the recessed portion and may provide a stop to determine spacing between the collars In figure 3c the additional annular flange (30) is provided with a radial hole (27) for receiving a grub screw to enable the inner bearing means to be fastened onto a shaft. In figure 3d the additional flange (30) is engagable with a collar (33) which has a hole (27) for receiving a grub screw.

As shown in figure 3e the inner bearing means may include two sleeve portions (34,35) each provided with a collar and a portion of the bearing surface (2) and the sleeve portions are engagable such that the bearing surfaces are adjacent and located between spaced apart collars Figure 4 shows a further embodiment of the invention in which the outer bearing means has an internally disposed locating flange (36) which extends across substantially the entire axial width thereof. The inner bearing means includes a peripheral bearing surface and two collars which extend one on each side of the flange of the outer bearing means One of the collars may be removable as shown in Figure 2.

WO 95/22011, PC'T/AU95100058 18 The intermediate bearing means includes a bearing ring inner bearing bush (13) in the form of a sleeve having an inner bearing surface adjacent the bearing surface of the inner bearing means (13) and an outer bearing surface adjust the inner bearing surface of the bearing ring The outer bearing bush member (16) includes axial bearing surfaces on its inner and outer circumference the inner bearing surface being adjacent the bearing ring and the outer bearing surface being adjacent the bearing surface on the inner circumference of the flange of the outer bearing means The outer bearing bush also includes two pairs of lips (37,38) one pair (37) disposed on the outer circumference at each end of the outer bearing bush (16) and one pair (38) disposed on the inner circumference at each end. The pair of lips (37) on the outer circumference extend between facing sides of the flange (36) and collars and the pair of lips on the inner circumference (38) extending one on either side of the bearing ring (10) to provide a radial being surface between the bearing ring (10) and collars Figures 5a and 5b shows an outer bearing means which includes a internally disposed locating flange The bearing rings (10) is fixed one each side of the flange for rotation with the outer bearing means such that bearing bush means is receivable adjacent each of the inner and outer circumference of the bearing ring. The collars of an inner bearing means (not shown) will be spaced apart from the distal ends of the bearing rings. In figure 5b the outer bearing means inner circumference is provided with annular recessed portions (38) each end for receiving the peripheral end of the collars from the inner bearing means such that the collars are spaced from the distal ends of the bearing rings The bearing means may also include channels or holes (39) for heat transfer or to allow the passage of a lubricant or cooling liquid.

Figure 5c shows the inner side of a thrust collar from an inner bearing means the thrust collar may be provided with a helical groove (40) on its inner surface to facilitate the removal of any particles which may become lodged in the bearing i 19 through entry of foreign matter or through wear. The helical groove transports 'particulate matter to the peripheral end of the collar. The collar may also or alternatively include holes (41) to allow a liquid to enter the bearing. The holes may be use to facilitate washing of the bearing and will preferably be located in each of the collars and may be present in any of the bearing components to holes being parallel to or at an angle to the axis.

Figures 5d shows an outer bearing means having an internal flange and a bearing ring (10) fused on one side. Bearing bush means includes rings (13,16) one (13) disposed adjacent the inner circumference of the bearing ring (10) and another (16) adjacent the outer circumference of the bearing ring (10) and the bush rings are joined by a web (42) extending adjacent the distal end of the bearing ring. The web (42) provides an axial bearing surface between the. distal end of the bearing ring and collar (not shown). The bush, means extends to 15 be flush with the ends of the outer bearing means to provide a seal to inhibit the passage of foreign particles into the bearing. The other side of the flange is provided with a bearing bush (16) having a lip (20) in its inner circumference adjacent the flange in accordance with the outer bearing bush (16) of Figures 1 and 2 except that the bush extends to the end of the outer bearing means (6) and between in inner circumference of the outer bearing means and the end of the collar to provide a seal.

Figure 5e shows an arrangement in which the inner bearing means includes a radial locating flange on its outer circumference which is provided with a fused bearing ring The ends of the inner bearing means also includes annular recesses (43) to receive the periphery of a collar attached to an outer bearing means. Bush means including inner and outer rings (13,16) are joined by a web (42) at a distal end of the bearing ring The other side of the flange is provided with an inner bearing bush (13) with a lip on its outer circumference disposed adjacent the side of the flange Recessed portions (43) are i orovided at eacn end of the inner bearing means for receiving colars of outer bearing means which are rotatable about the recessed portions (43).

I- sI WO 95/22011 PCT'/AU95/00058 Figures 6a to 6f show inner bearing means for use in the present which is in the form of a sleeve having a bore for receiving a shaft. Figures 6a and 6b show an inner bearing means having a collar A bearing surface is located on one side of the collar with a thrust collar (4) being receivable on a recessed portion on the other side of the bearing surface to receive a flange and intermediate bearing means between the collars for rotation thereabout. The bearing surface of the sleeve is preferably cylindrical.

The sleeve includes an annular constrictable portion (44) comprising a multiplicity of slots (45) extending through the sleeve at one end. The slots (45) are circumferentially spaced to provide a multiplicity of deformable portions The sleeve narrowingly tapers toward the slotted the inner bearing means is provided with a constrictor means in the form of a locating nut The inner circumference (48) of the locking nut and the outer circumference of the constrictable portion of the sleeve have coacting threaded portions (48,49).

To fasten the bearing on a shaft located in the sleeve the locking nut (47) is tightened upon the threaded constrictable portion (44) and thereby urged along the sleeve. Its inner circumference (48) of the nut (47) provides an inward force on the tapered surface of the constrictable portion (44) causing an even inwardly deforming force on the segments (46) between the slots to lock the sleeve into the shaft (48) as shown in 6b. In an alternative embodiment the inner surface of the locking nut (47) narrowingly tapers to provide a constricting force to the constrictable portion (44) of the sleeve which may or may not include a tapered portion.

In the embodiment shown in figures 6c to 6d the sleeve comprises a flange (7) and a bearing surfaces on either side of the flange The sleeve includes a constrictable portion (44) including a multiplicity of slots (45) which extend through I- _I II wo 95/220 it PCTAU95/00058 21 the sleeve and provide deformable sections (46) there between which are inwardly tapered and/or have an inwardly tapered outer surface. The sleeve has a threaded portion (49) adjacent the constrictable portion (44) and a locking nut (47) comprises a coacting threaded portion (48) adjacent the end received on the sleeve and the coacting threaded portions urge the locating nut (47) into the sleeve. The locking nut (47) includes an annular inner flange (50) which on tightening of the locking nut (47) on the sleeve urges the constrictable portion (46) inward to lock onto the shaft (51) as shown in 6d.

Figure 6e and 6f show a further arrangement in which the locking nut (47) is provided with a thrust collar which may on assembling the bearing provide one of the thrust collar disposed on one side of a inward flange on the outer bearing member On assembling the bearing one set intermediate bearing means is located on the bearing surface. The outer bearing means is then slid onto the bearing surface followed by the second set of intermediate bearing means and the thrust collar is engaged with the thread of the sleeve (49) and may be tightened as shown in Figure 6f to lock the bearing onto the shaft.

Figures 7a and 7b shows a portion of an inner bearing means comprising a tapered or frustoconical sleeve (52) having a bearing surface and an axial collar at the large diameter end of the sleeve A thrust collar (not shown) may be received in thf smaller diameter end. The inner circumference of the sleeve may be provided with a spline or serrations (53) or other means for engaging a drive shaft or the like.

Figure 7c shows a race portion of an inner bearing means which includes a sleeve (52) with a cylindrical bearing surface and a collar at one end. A thrust collar (not shown) is receivable at the other end of the sleeve. The bore of the sleeve is provided with spline or serrations (53) for receiving a drive shaft or the like.

WO 95/22011 PC'TAU95/()O(S8 22 Figures 8a to 8h show alternative configurations of a outer circumference of the outer bearing means The outer circumference may be cylindrical as shown in 8a convex as shown in 8b particularly of spherical section as shown in 8f. The outer bearing means may include a radial flange or radial protrusions (54) spaced about its outer circumference as shown in 8c. Recesses such as the concave Vshape grooves may be present as shown in 8d and 8e. A peripheral tapered flange (55) adjacent one edge may be useful in a roller for a conveyor belt or the outer bearing means may be a cam as shown in 8h.

The outer bearing means may be in the form of a housing as shown in figures 9a to 9d such as a pillar block housing (figure 9a) a two flange housing (figure 9b) or four flange housing (figure 9c) having holes (56) for fifing the housing. The outer bearing means may also be in the form of a sprocket or geared when as shown in figures 9c and 9f.

In an alternate embodiment the outer bearing means is receivable into a housing of one of the shapes shown in figures 9a to 9f. The outer bearing means may be admitted to the housing by using a split housing and the outer bearing means may have a convex outer circumference spherical section see figure 8f and the housing a concave inner circumference of corresponding section to allow the outer bearing means to pivot within the housing to align with a shaft or the like. A hanger type housing is depicted in figure 9d and includes means for engaging an article (57) to be suspended from a conveyance line to be engaged by the outer bearing means.

A particular advantage of the preferred bearing of the invention shown in Figures 1 and 2 is that each of the intermediate bearing components including the bearing bushes and bearing ring are rotatable with respect to one another which significantly reduces wear and minimises build up of heat. Between the inner and outer bearing means there are at least four pairs of radial bearing surfaces and at anytime, during operation of the bearing, there may be relative ratation at any one or more of these pairs of surfaces. Each of the components of the WO 95/22011 PC'I1/AU95/00058 23 intermediate bearing means may rotate at a different speed to the inner or outer bearing means and other components. Further, on the build up of fraction and heat between a portion of bearing surfaces they tend to stick together and the presence of a multiplicity of pairs of bearings surfaces allows the bearing rings to rotate intermittently or and/or at different speeds to one another. The bearing ring and bushes therefore appear to float.

The bearing component and in particular the bearing ring and inner and outer bushes evenly distribute friction and wear and provide more effective dissipation of heat effectively eliminating the incidence of ceasure even at high speed and under great loads.

The presence of load forces in the axis of the bearing generally exacerbates the problems of wear and ceasure in conventional plain bearing. In the presence invention the presence of lips on the bushes which extend between the bearing ring and collar and the locating flange and bearing ring to provide four pairs of bearing surfaces on each side of the locating flange. The bearing of the invention therefore provides excellent resistance to wear from axial loads.

The use of a bearing as the wheel hub of a heavy vehicle provides a severe test of its performance and despite the existence of plain bearings for many years the bearings used in the wheels of vehicles are generally bearings containing roller balls.

A bearing according to Figure 1 and Figure 2 above was constructed using an inner bearing means, outer bearing means and bearing ring constructed of aluminium impregnated with PTFE.

The bearing bushes were prepared from polyimide. The bearing was used in the wheel hub of a 1% tonnes off road vehicle which was driven at speeds of over miles per hour in swampy terrain frequently being submerged in sea water. The bearing was also used in the wheel hub of a trailer with a total loaded weight of 3 WO 95/22011 PCT/AU95/00058 24 tonnes. In each case the bearing performed excellently showing little or no sign of wear after extended use.

Vehicle wheels of the present invention are suitable for use in vehicles used in detecting mines and explosives as they do not generate static electricity. This feature also makes the bearing of the invention desirable for use in scientific instruments in underground mining operations or in other circumstances where it is desirable to guard against static electricity and or the use of ferrous metals or their alloys.

Claims

1. A plain bearing assembly comprising: inner bearing means providing an annular peripheral bearing surface; outer bearing means coaxial with the inner bearing means and providing an inner annular bearing surface; and at least one set of intermediate bearing means coaxial with the inner bearing means and outer bearing means, each set of intermediate bearing means providing a bearing ring having an inner annular bearing surface, an outer annular bearing surface, and at least one radial surface and providing bearing ring bush means rotatably mounted about the inner bearing means and rotatable with respect to the bearing ring and the outer bearing means, the bearing ring bush means providing a bearing surface adjacent to the inner annular bearing surface of the bearing ring, a bearing surface adjacent the outer annular bearing surface of the bearing ring, and an axial bearing surface adjacent to each of the radial surfaces of the bearing ring in a coaxial direction,

2. A plain bearing assembly according to claim 1, wherein the bearing ring bush means includes: an inner bearing ring bush member rotatably mounted about the inner bearing means and rotatable with respect to the bearing ring and having a peripheral bearing surface adjacent the inner bearing surface of the bearing ring; and an outer bearing ring bush member rotatably mounted about the bearing ring and having an inner bearing surface adjacent the outer annular bearing surface of the bearing ring and an axial bearing surface on the inner bearing surface adjacent one of the radial bearing surfaces of the bearing ring in a coaxial direction. 26

3. A plain bearing assembly according to claim 1, wherein the outer bearing means includes a locating flange Find a radial bearing surface on each side of the locating flange, the inner bearing means includes a bearing surface and a pair of collars, one collar extending on each side of the locating flange of the outer bearing means, and two sets of intermediate bearing means are disposed between facing sides of the locating flange and collars having one set intermediate bearing means on each side of the locating flange.

4. A plain bearing assembly according to claim 1, wherein the bearing ring of each of the intermediate bearing means is rotatable with respect to each of the inner and outer bearing means. S

5. A plain bearing assembly according to claim 2, wherein each of the inner and outer bearing ring bush members alternates between a condition in which the inner and outer bearing ring bush members are stationary with respect to a bearing surface of smaller circumference and rotate with respect to a bearing surface of greater circumference and a condition in which the inner and outer bearing ring bush members are stationary with respect to a bearing surface of greater circumference and rotatable with respect to a bearing surface of smaller circumference.

6. A plain bearing assembly according to claim 3, wherein at least one of the inner and outer bearing ring bush members in each set of intermediate bearing means is wider than the bearing ring and includes one or more lips which cooperate with the bearing ring to retain the bearing ring spaced apart from the facing sides of the locating flange and pair of collars.

7. A plain bearing assembly according to claim 6, wherein the inner and outer bearing ring bush members in each set of intermediate bearing means together include two or more lips, one lip disposed between the bearing ring and the locating flange and another lip disposed between the bearing ring and one of the pair of collars. r' 0 27

8. A plain bearing assembly according to claim 7, wherein one of the lips radiates from an adjacent side of the inner bearing bush member and an outer lip is internally disposed adjacent the side of the outer bearing member and the lips provide alignment of the bearing ring and provide axial bearing surfaces between the bearing ring and inner and outer bearing means.

9. A plain bearing assembly according to claim 8, wherein the lips of the inner and outer bearing bush members include a plurality of radiating grooves circumferentially spaced on an outer face thereof.

A plain bearing assembly according to claim 1, wherein of components selected from a first group consisting of the bearing ring bush means and a .second group consisting of the inner bearing means, the outer bearing means, and the bearing ring is formed of a plastic and the other group of components is formed of metal.

11. A plain bearing assembly according to claim 10, wherein each of the inner and outer bearing means and the bearing ring is formed of metal and the bearing ring bush means is formed of plastic.

S. A plain bearing assembly according to claim 3, wherein the bearing ring of the intermediate bearing means includes a proximal end fused to one of the facing sides of the pair of collars and the locating flange and a distal end spaced apart from the other of the facing sides.

13. A plain bearing assembly according to claim 12, wherein either of the inner or outer bearing ring members bush includes two annular bush rings, one ring disposed adjacent to the outer bearing surface of the bearing ring and another ring adjacent to the inner bearing surface of the bearing ring and wherein the two annular bush rings are joined by a web extending adjacent the distal end of the bearing ring.

14. A plain bearing assembly according to claim 2, wherein at least one of the inner bearing ring bush member and the outer bearing ring bush member has a plurality of grooves.

A plain bearing assembly according to claim 2, wherein the bearing ring has a smaller axial width than at least one of the inner and outer bearing ring bush members.

16. A plain bearing assembly according to claim 1, wherein the bearing ring bush means and the bearing ring are coaxial with respect to each other.

17. A plain bearing assembly according to claim 1, wherein the outer bearing means includes a plurality of circumferentially spaced holes allowing the outer bearing means to be fixed to a wheel.

18. A plain bearing assembly according to claim 17, wherein the inner, intermediate, and outer bearing means are used as a hub of the wheel. g

19. A plain bearing assembly according to claim 3, wherein one of the pair of collars is a thrust collar. A plain bearing assembly according to claim 19, wherein the inner bearing means has a annular recess that is flared, the flared annual recess attaches to the thrust collar. DATED this 4th day of February 1998. PLASTIC BEARINGS HOUSINGS AUSTRALASIA PTY LTD WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA SKP:SMM:JL VAX doc

20 AU1661095.WPC