AU754835B2 - Roller shell - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT 0* Name of Applicant: Actual Inventors Address for service is: Prok Group Limited Andrew Douglas Menzie and Stephen Muraszko WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: Roller Shell Details of Associated Provisional Application No(s): PP8029 filed on 5 January 1999 The following statement is a full description of this invention, including the best method of performing it known to me:- -2- TITLE: "ROLLER SHELL" FIELD OF THE INVENTION This invention relates to conveyer rollers and in particular the roller shells of the rollers used in such conveyors.

BACKGROUND OF THE INVENTION It has been found over a period of time that the service failure of conveyer rollers .i will often be as a result of bearing failure which is as a result of the ingress of dirt and/or water into the bearing past the seals which are associated with the bearing in the roller bearing seal assembly. Most conveyor assemblies are used 10 in conveying bulk material and are installed in bulk handling facilities in which a dust laden atmosphere and/or a wet environments is the norm and in which high pressure water is often used to wash down the conveyer assembly for 00 maintenance cleaning. As a result the roller bearing assembly must be able to withstand such harsh conditions. In order to prevent water and other foreign materials from being drawn into the bearing assembly it is a common practice to provide a breather aperture in the roller shell to enable the pressure within the shell to equalise to the ambient pressure through the aperture rather than S"through the bearing assembly. However in wet environments and under wash down conditions it is possible for water to enter the interior of the shell through the aperture.

DISCLOSURE OF THE INVENTION Accordingly, the invention resides in a roller shell adapted to be supported from a shaft to be rotatable on the shaft wherein the shell is hollow and is formed with a central opening at each end wherein at least one end face accommodates a breather which comprises an aperture formed through the at least one end face -3to provide communication between the interior and exterior of the shell, said aperture being closed by a solid porous element.

According to a preferred feature of the invention the solid porous element is pervious to air but is substantially impermeable by water.

According to a preferred feature of the invention the solid porous element is substantially impervious to water in both liquid and gaseous form.

According to a preferred feature of the invention the roller shell is supported from the shaft by a roller bearing seal assembly located at each central opening, each roller bearing seal assembly comprising an outer seal assembly and a bearing, 10 wherein the outer seal assembly comprises, a first annular member adapted to be non-rotatably supported on the shaft and which is located outermost, a second annular member adapted to be supported from the shell located closely adjacent the first annular member, the radial extent of the members being such that they overlap, wherein the outer seal assembly further comprises a resilient flexible sealing element supported on the first or second annular member and being in slidable contact with the opposed face of the other annular member.

According to a further preferred feature of the invention the sealing element :defines a channel shaped surface between the first and second annular members which is directed radially outwardly. According to one embodiment the outer edge of the sealing element comprises a first lip seal which is radially innermost and which is in sliding contact with the other annular member, the sealing element further comprising a second lip seal which is radially outermost and is in sliding contact with the other annular member and is deflected radially outwardly. According to a feature of the embodiment the first lip seal is in light sliding contact with the other annular member. According to another embodiment the outer edge of the sealing element is formed as a flange which extends radially outward from the sealing element, said flange being in sliding sealing contact with the other annular member.

-4- According to a preferred feature of the invention the sealing element is supported on the second annular member.

According to a preferred feature of the invention the second annular member has a flange at its inner edge. According to one embodiment the flange at least partially supports the sealing element.

According to a preferred feature of the invention the sealing element is formed of formed from an elastomeric material or a material having elastomeric like properties.

According to a preferred feature of the invention the second annular member is adapted to be sealingly engaged with the shell. According to a preferred feature of the invention the sealing engagement is provided by a resilient sealing medium supported from the second annular member. According to one embodiment the sealing medium is bonded to the outer radial face of the second annular member. According to a preferred feature of the invention the sealing medium is formed from an elastomeric material or a material having elastomeric like properties. According to another embodiment the second annular member is formed as a composite member comprising a rigid annulus and a moulding :supported by the rigid annulus. According to a feature of the embodiment the sealing medium is formed as an integral part of the moulding. According to a feature of the embodiment the moulding is formed from an elastomeric material or a material having elastomeric like properties.

According to a preferred feature of the invention the outer seal assembly further comprises a rigid shaft seal adapted to be non-rotatably supported on the shaft and located between the first annular member and the bearing; wherein the shaft seal comprises a first annular flange extending radially outwardly from the shaft into the space between the second annular member and the bearing, said shaft seal having an outer radial surface which is closely adjacent the inner radial face of the second annular member, said shaft seal being configured to frictionally engage the first annular member. According to a preferred feature of the invention the shaft seal is formed of a substantially rigid plastics material.

According to one embodiment the shaft seal supports the first annular member from the shaft. According to one embodiment the outer radial surface comprises a second annular flange extending radially outwardly from the shaft such that its outer periphery is located closely adjacent the inner radial face of the second annular member. According to a feature of the embodiment the outer radial surface of the shaft seal and inner radial face of the second annular member have an axial extent. According to an alternative embodiment the flange at the inner edge of the second annular member provides the inner radial face of the second annular member.

According to a preferred feature of the invention the roller bearing seal assembly further comprises an inner seal, said inner seal being intended to be located adjacent the innermost face of the bearing, said inner seal adapted to be non- 15 rotatably supported from the shaft proximate the inner edge of the annular flange of the roller shell, the diameter of the outer radial face of the inner seal being such that the outer radial face is in closely spaced relation to the inner edge when the inner seal is in position in a roller shell, the axial dimension of the outer radial face of the inner seal being such that the outer radial face extends to S* 20 either side of the inner edge when the inner seal is in position in a roller shell and the outer radial face is formed at the inner end of the inner seal relative to the roller shell with a first lip which is spaced inwardly relative to the roller shell, from the inner edge when the inner seal is in position in a roller shell. According one embodiment of the invention the outer radial face is substantially parallel to the central axis. According to an alternative embodiment the outer radial face is convergent in the direction of the first lip. According to a preferred feature of the invention the outer end of the outer radial face relative to the roller shell, is formed with a second lip which is spaced outwardly, relative to the roller shell, from the inner edge when the inner seal is in position in the roller shell whereby the outer radial face has a generally channel shaped configuration defined by the first and second lip and the portion of the outer radial face between the first -6and second lips. According to a preferred feature of the invention the second lip is dimensioned to be in sliding sealing relationship with the outer radial portion of the bearing when the inner seal is in position in a roller shell. According to a preferred feature of the invention the portion of the outer radial face between the first and second lips is convergent in the direction from the second lip to the first lip. According to a preferred feature of the invention the first lip is formed with a sharp outer edge. According to a preferred feature of the invention the first lip is spaced outwardly from the inner edge a sufficient distance such that vertical plane containing the lower most extent of the first lip is spaced inwardly, relative to the roller shell, from the vertical plane containing the lowermost extent of the rotational path of the inner edge when the inner seal is in position in a roller shell o and the roller shell is in use.

:0:*.The invention will be more fully understood in the light of the following description of several specific embodiments.

15 BRIEF DESCRIPTION OF THE DRAWING The description is made with reference to the accompanying drawings of which: Figure 1 is a part sectional elevation of a roller shell supported upon a shaft by a S' roller bearing seal assembly according to the first embodiment; and Figure 2 is a part sectional elevation of a roller shell supported upon a shaft by a roller bearing seal assembly according to the second embodiment.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION The first embodiment comprises a roller bearing seal assembly which can be utilised to support a roller shell 11 from a shaft 13. The roller shell 11 is of a generally conventional form and is formed at each end with a central recessed portion which is formed by an inner flange 12 which is substantially parallel with the outer periphery of the roller shell and which terminates at its innermost end -7with a radial flange 14 which is inclined inwardly with respect to the radial axis.

The roller bearing seal assembly comprises an outer seal assembly 15, a bearing 17 and an inner seal 19.

The outer seal assembly 15 comprises a first annular member or deflection seal 21 which is formed of sheet metal and is located axially outermost. The deflection seal 21 is adapted to be frictionally fixed to the shaft 13 and in use is retained in position by a retainer circlip 23. The outer portion 25 of the deflection seal is formed such that it is inclined from the radial axis in the direction of the bearing 17.

The outer seal assembly further comprises a second annular member or intermediate seal 27 which is formed of sheet metal and is frictionally received within the flange 12 which defines the annular recess in the end face of the roller shell. To ensure a tight sealing engagement between the intermediate seal 27 and the roller shell 11, the outer radial face 33 of the intermediate seal is coated with a resiliently compressible sealing medium 35. The sealing medium is sealingly engaged with the innermost radial face of the flange 12 of the roller shell. The sealing medium comprises an elastomeric material or a material having elastomeric-like properties and is moulded onto the outer radial face 33.

The use of the sealing medium 35 between the intermediate seal 27 and the roller shell presents a significant improvement over the use of direct frictional engagement of the intermediate seal with the roller shell. Such advantages include: 1. the resilient compressible nature of the sealing medium ensures that it effectively seals the junction between the roller shell and the intermediate seal to prevent the passage of water past the sealing medium; -8- 2. the resilient compressible nature of the sealing medium enables the sealing medium to accommodate for any lack of circularity between the intermediate seal and the roller shell whilst maintaining a sealing engagement there between and as a result serves to keep the outer seal centralised in the roller shell by accommodating for deformation in the flange 12 of the roller shell and/or the intermediate seal; 3. in the case of direct metal to metal engagement between the intermediate seal and the roller shell which has been the practice in 10 the past, any plastic deformation of the intermediate seal and/or the flange may result on the loosening of the outer seal in the roller shell and a reduction in the seal formed between the roller shell i. ~and the intermediate seal whereas the use of the sealing medium serves to accommodate for any such deformation without a 15 significant reduction in the sealing action or the frictional S"engagement with the roller shell; 4. the resilient compressible nature of the sealing medium means that the degree of tolerance in the formation of the sealing medium is not as great as that required with direct metal to metal contact 20 between the intermediate seal and the roller shell and as a result the sealing medium may have a greater diameter than the internal diameter of the radial flange which can serve to increase the sealing and retention properties of the sealing medium; and the coefficient of sliding friction between the sealing medium and the flange 12 is much greater than can be achieved by direct metal to metal contact between the intermediate seal and the roller shell which serves to ensure that the outer seal is retained in the roller shell and is able to withstand axial forces which may be exerted on the outer seal.

-9- The inner radial edge of the intermediate seal 27 is provided with an axially directed flange 31 which is directed axially in the direction of the deflection seal 21. To further enhance the sealing action of the outer seal assembly the axially directed flange 31 of the intermediate seal 27 supports a sealing element 39 which extends axially from the intermediate seal 27 in the direction of the deflection seal 21 to be in a sliding and sealing engagement with the inner face of the deflection seal 21. The sealing element 39 is formed of an elastomeric material or a material having elastomeric-like properties and is bonded to the intermediate seal 27. The outer axial edge of the sealing element which is in sliding contact with the deflection seal 21 is formed as a double lip seal having a first lip seal 41 which is located radially innermost and which is intended to be in light sliding engagement with the inner face of the deflection seal 21. The second lip seal 43 is located radially outermost and has a length such that on engagement with the deflection seal 21, its outer edge is deflected radially outwardly to form a gutter or channel between the deflection seal 21 and the intermediate seal 27.

The sealing element 39 provides a seal between the deflection seal 21 and the intermediate seal 27 as a result of it providing a barrier between the two elements. In addition the sealing element 39 provides a gutter or channel 20 between the deflection seal and intermediate seal which will direct any water incident upon the sealing element away from the sealing interengagement between the second lip seal 43 and the deflection seal 21. As a result when the sealing element 39 is stationary the water will be caused to flow downwardly over the sealing element and out of the space between the deflection seal 21 and the intermediate seal 27. On rotation of the sealing element 39 as a result of rotation of the roller shell 11 and thus the intermediate seal 27 any water collecting in that gutter or channel to be centrifugally ejected from the space between the deflection seal 21 and the intermediate seal 27. Furthermore in the event of the sealing element being subjected to increased fluid pressure the sealing action between the second lip seal 43 and the inner face of the deflection seal 21 will increase to resist the entry of fluid past the sealing element 32. A further advantage of the sealing element 39 is that in use the centrifugal force which is exerted on the outer lip seal 43 of the sealing element 39 with rotation of the roller will cause the lip to be deflected outwardly in such a way as to reduce the sealing pressure between the outer lip seal 43 and the deflection seal 10 which therefore reduces the seal drag. In addition, when no pressure is being applied externally, any excess grease which is accommodated within the seal can purge past the sealing element.

The outer seal assembly 15 further comprises a shaft seal 29 which is frictionally received on the shaft 13 and is located between the deflection seal 21 and the 10 bearing 17. The shaft seal is formed of a suitable rigid hard plastics material.

The shaft seal comprises a bush-like body which is received on the shaft and an .o.integrally formed first radial flange 31 which extends into the space defined between the intermediate seal 27 and the bearing 17. The outer axial end of the shaft seal is formed with a rebate 32 which will frictionally receive the axially 15 innermost edge of the deflection seal 21 between the shaft 13 and the shaft seal *29. In this regard the axially innermost edge of the deflection seal is formed with an inwardly directed flange 34 which has in internal diameter corresponding to the external diameter of the shaft and an external diameter corresponding to the internal diameter of the rebate 32 in order that the deflection seal is frictionally "20 engaged with both the shaft 13 and the shaft seal 29.

In addition, the shaft seal 29 is formed with a second radial flange 30 which is spaced axially outward from the first radial flange 31 and is in opposed relation to the axially directed flange 31 of the intermediate seal 27. The diameter of the second radial flange is such that its outer periphery is in a closely spaced relationship with the inner radial face of the axially directed flange 31. The presence of the second radial flange and its close spacing from the intermediate seal 27 serves to enhance the sealing effectiveness of the roller bearing seal assembly.

-11 As a result of the frictional interengagement between the deflection seal 21 and the shaft seal 29 with the intermediate seal 27 located between them, the outer seal assembly 15 can be assembled as a pre-assembled cartridge which can be applied as a unit to the end of a roller and/or over the shaft. In addition the second radial flange 20 serves to centralise and locate the shaft seal 29 relative to the intermediate seal in the assembly of the outer seal as a pre-assembled cartridge. The close tolerance between the second annular flange 30 and the intermediate seal further serves to keep the intermediate seal 27 centralised in the pre-assembled cartridge which facilitates the location of the outer seal assembly 15 on the shaft and into the recess of the roller shell.

The sealing arrangement provided by the outer seal assembly 15 is such that it will prevent the entry of water past the outer seal assembly. This is effected by the utilisation of the resiliently compressible sealing medium 35 between the intermediate seal 27 and the roller shell 11 in order to effect the interference fit 15 between the intermediate seal 27 and the roller shell 11. The sealing o arrangement is further enhanced by utilisation of the sealing element 39 which not only provides a barrier between the deflection seal 21 and the intermediate seal 27 but also serves to provide a gutter or channel between the deflection seal and intermediate seal which will divert any water away from the sealing S".i 20 engagement between the sealing element and the deflection seal. In addition on rotation of the sealing element as a result of rotation of the roller shell 11 and thus the intermediate seal 27, the water collecting in that gutter will be centrifugally ejected through the space provided between the outer lip 25 of the deflection seal 21 and the intermediate seal 27. In addition the sealing action of the outer seal assembly is enhanced by the second flange of the shaft seal and its closely spaced relationship with the intermediate seal.

The outer seal assembly 15 of the first embodiment provides a pre-assembled cartridge which when installed in a roller shell and on a shaft has improved sealing properties over the prior art.

-12- The roller bearing seal assembly according to the first embodiment further comprises the rear seal 19 which comprises an inner radial portion 45 which is frictionally received over the shaft 13. On application of the rear seal to the shaft 13 and to the roller shell 11 the axially outermost face of the inner radial portion (relative to the roller shell) bears against inner axial face of the bearing 17. The rear seal further comprises an outer radial portion 47 which extends radially outwardly from the inner portion 14 and has an outer profile which is of a channel shaped configuration which is defined by a first radial lip 49 which is remote from the bearing 17 and a second radial lip 51 which is proximate the bearing 17. In addition, the proximate radial lip 51 has a greater radial extent than the remote radial lip 49 while the outer axial face of the outer portion 47 between the radial lips 49 and 51 is inclined in the direction of the shaft 13 from the proximate radial lip 51 to the remote radial lip 49. In mounting the rear seal *to the shaft 13 and the roller shell the radial lips 49 and 51 are located to opposite sides of the inner radial flange 14 of the bearing shell 11. The channel o or gutter which is provided at the outer radial extent of the rear seal 19 provides *o .a labyrinth which serves to resist the ingress of any water into the region of the bearing from within the body of the shell 11 both when the roller is stationary and when it is rotating.

20 The remote radial lip 49 is configured to provide a sharp outer edge. The S" purpose of the sharp edge is to inhibit the collection of water droplets at the edge and to promote the shedding of water from the rear seal 19. In addition the remote radial lip 49 is spaced sufficiently from the radial flange 14 of the roller shell such that even when the central longitudinal axis of the roller shell is inclined upwardly the outer edge is located outward of the adjacent edge of the radial flange 14. Therefore when water is shed from the radial lip it will fall clear of the inner edge of the flange 14.

It is a further feature of the embodiment that the roller shell 11 is provided with a breather aperture 55 on at least one end face which serves to allow for the passage of air into and out of the shell cavity to accommodate for pressure -13variations within the body of the roller shell. The purpose of the breather aperture is to ensure that there is a substantial equalisation of pressure between the interior of the shell and the environment and to ensure that any air flow that is induced as a result of an inequality between the interior and exterior is not required to pass through the roller bearing seal assembly. The breather aperture 55 is closed by a plug 57 which is formed of a rigid pervious material which is such that it will permit the passage of air through the breather aperture but will resist the passage of water molecules water in a liquid or gaseous form) through the breather aperture 55. A suitable form of material which can be used in the plug can comprise a sintered glass or like ceramic o *material. Alternatively the material can comprise a plastics material. According to one example of material the pore size is of the order of 3 micron. As a result of the presence of the plug the flow of air into the roller shell will not result in water being drawn into the shell when the shell is in wet environment. In addition the selective filtering of water molecules from the air as it flows into the roller shell will reduce the likelihood of water collecting in the shell as a result of condensation.

The second embodiment as shown at Figure 2 comprises a roller bearing seal assembly which can be utilised to support a roller shell 111 from a shaft 113.

*i 20 The roller shell 111 is of a generally conventional form and is formed at each end with a central recessed portion which is formed by an inner flange 112 which is substantially parallel with the outer periphery of the roller shell and which terminates at its innermost end with a radial flange 114 which is inclined inwardly with respect to the radial axis. The roller bearing seal assembly comprises an outer seal assembly 115, a bearing 117 and an inner seal 119.

The outer seal assembly 115 comprises a first annular member or deflection seal 121 which is formed of sheet metal and is located axially outermost. The deflection seal 121 is adapted to be frictionally fixed to the shaft 113 through the shaft seal 129 in a manner which will be described later. In use the deflection seal and shaft seal 129 is retained in position by a retainer circlip 123. The outer -14portion 125 of the deflection seal is formed such that it is inclined from the radial axis in the direction of the bearing 117.

The outer seal assembly further comprises a second annular member or intermediate seal 127 which is formed as a single element and is a composite element comprising a sheet metal annulus 126 which supports a moulding 128 formed of an elastomeric material or a material having elastomeric-like properties. The sheet metal annulus is formed at its outer edge is formed with a flange 133 which in use is to be directed towards the bearing 117. The moulding 128 is received over the outer face of the annulus. In addition the moulding 10 extends over the radial outermost surface of the flange 133 to define a first sealing element 135 which is sealingly and frictionally received within the flange 112 which defines the annular recess in the end face of the roller shell. The resilient compressible nature of the moulding 128 ensures a tight sealing engagement between the flange 112 of the roller and the first sealing element 15 135 of the intermediate seal 127.

The use of the first sealing element 135 which is an integral part of the moulding between the intermediate seal 127 and the flange of the roller shell presents a *o significant improvement over the use of direct frictional engagement of a metal intermediate seal with the roller shell. Such advantages include: 1. the resilient compressible nature of the moulding ensures that the first sealing element 135 effectively seals the junction between the roller shell and the intermediate seal to prevent the passage of water past the sealing medium; 2. the resilient compressible nature of the first sealing element 135 enables the first sealing element to accommodate for any lack of circularity between the intermediate seal and the roller shell whilst maintaining a sealing engagement there between and as a result serves to keep the outer seal centralised in the roller shell by accommodating for deformation in the flange 112 of the roller shell and/or the intermediate seal; 3. in the case of direct metal to metal engagement between the intermediate seal and the roller shell which has been the practice in the past, any plastic deformation of the intermediate seal and/or the flange may result on the loosening of the outer seal in the roller shell and a reduction in the seal formed between the roller shell and the intermediate seal whereas the use of the first sealing element 135 serves to accommodate for any such deformation without a significant reduction in the sealing action or the frictional engagement with the roller shell; 4. the resilient compressible nature of the first sealing element 135 means that the degree of tolerance in the formation of the first S:sealing element 135 is not as great as that required with direct 15 metal to metal contact between the intermediate seal and the roller shell and as a result the first sealing element may have a greater diameter than the internal diameter of the radial flange which can serve to increase the sealing and retention properties of the sealing medium; and 5. the coefficient of sliding friction between the first sealing element 135 and the flange 112 is much greater than can be achieved by direct metal to metal contact between the intermediate seal and the roller shell which serves to ensure that the outer seal is retained in the roller shell and is able to withstand axial forces which may be exerted on the outer seal.

The inner radial edge of the moulding 128 of the intermediate seal 127 is formed with a second sealing element 139 which extends axially from the intermediate seal 127 in the direction of the deflection seal 121 to be in a sliding and sealing -16engagement with the inner face of the deflection seal 121. The moulding in the region of the inner end of the second sealing element 139 is formed to extend around the inner radial edge of the annulus 126 such that it is fixed to both faces of the annulus 126 and provides an inner radial face 131 which is in opposed relation to the shaft. The outer axial edge of the second sealing element 139 which is in sliding contact with the deflection seal 121 is formed as a flange 143 which extends radially outwardly from the outer edge of the second sealing element 139 to lie parallel to the inner surface of the deflection seal 121 and to be in light sliding engagement with the inner face of the deflection seal 121. As a result of the configuration of the outer edge of the second sealing element 139 SS.- a gutter or channel is defined by the second sealing element 139 between the deflection seal 121 and the main body of the intermediate seal 127.

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SThe second sealing element 139 provides a seal between the deflection seal 121 and the intermediate seal 127 as a result of it providing a barrier between S 15 the two elements. In addition the second sealing element 139 provides a gutter S Se or channel between the deflection seal and intermediate seal which will direct any water incident upon the second sealing element 139 away from the sealing interengagement between the flange 143 and the deflection seal 121. As a result when the second sealing element 139 is stationary water will be caused to S- 20 flow away from the sealing interengagement between the flange 143 and the deflection seal 121, downwardly over the second sealing element and out of the space between the deflection seal 121 and the intermediate seal 127. On rotation of the second sealing element 139 as a result of rotation of the roller shell 111 and thus the intermediate seal 127, any water collecting in that gutter or channel will be caused to be to be centrifugally ejected from the space between the deflection seal 121 and the intermediate seal 127. Furthermore in the event of the second sealing element 139 being subjected to increased fluid pressure the sealing action between the flange 143 and the inner face of the deflection seal 121 will increase to resist the entry of fluid past the second sealing element 139. A further advantage of the second sealing element 139 is that in use the centrifugal force which is exerted on the flange 143 of the second -17sealing element 139 with rotation of the roller will cause the flange to be deflected outwardly in such a way as to reduce the sealing pressure between the flange 143 and the deflection seal 10 which therefore reduces the seal drag. In addition, when no pressure is being applied externally, any excess grease accommodated within the seal can purge past the second sealing element 139.

The outer seal assembly 115 further comprises a shaft seal which is frictionally received on the shaft 113 and is located between the circlip 123 and the bearing 117. The shaft seal is formed of a suitable rigid and hard plastics material. The shaft seal comprises a bush-like body which is received on the shaft and an 10 integrally formed first radial flange 131 which extends into the space defined 4.0 between the intermediate seal 127 and the bearing 117. The outer axial end of o@@o 0o:6.* the shaft seal is formed with a rebate 132 on its outer radial face which frictionally receives the axially innermost edge of the deflection seal 121. In this regard the axially innermost edge of the deflection seal is formed with an 15 inwardly directed flange 134 which has in internal diameter corresponding to the external diameter of the rebate 132 in order that the deflection seal is frictionally o engaged with the shaft seal.

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The mounting of the deflection seal to the shaft 121 via the shaft seal 129 S.o: according to the second embodiment serves to maintain the deflection seal out °a 20 of engagement with the shaft. As a result the shaft is not damaged in the event of the deflection seal undergoing some angular and/or axial movement relative to the shaft due the absence of any metal to metal contact.

In addition, the intermediate portion 130 of the shaft seal 129 between the rebate and the first radial flange 131 has a diameter which is very similar to but less than the internal diameter of the inner radial face 131 of the intermediate seal 127 and is in opposed relation to the inner radial face 131 of the intermediate seal 127. As a result the outer periphery of the intermediate portion is in a closely spaced relationship with the inner radial face 131 of the intermediate seal 127 and that close spaced relation has a significant axial -18extent corresponding to the length of the inner radial face 131. The close spacing of the intermediate portion from the intermediate seal and the axial extent of that close spacing serves to enhance the sealing effectiveness of the outer seal assembly.

As a result of the frictional interengagement between the deflection seal 121 and the shaft seal 129 with the intermediate seal 127 located between them, the outer seal assembly 115 can be assembled as a pre-assembled cartridge which can be applied as a unit to the end of a roller and/or over the shaft. In addition the intermediate portion 131 of the shaft seal serves to centralise and locate the 10 shaft seal 129 relative to the intermediate seal 127 in the assembly of the outer seal as a pre assembled cartridge. The close tolerance between the intermediate portion 130 and the inner radial face of the intermediate seal 127 further serves to keep the intermediate seal 127 centralised in the preassembled cartridge which facilitates the location of the outer seal assembly 115 on the shaft and into the recess of the roller shell. Furthermore the inner end of the rebate 132 serves in axially locating the deflection seal on the shaft seal in the correct position in the assembly of the outer seal 115.

The sealing arrangement which is provided by the outer seal assembly 115 of the second embodiment is such that it will prevent the entry of water past the outer seal assembly. This is effected by the utilisation of the resiliently compressible first sealing element 135 between the intermediate seal 127 and the roller shell 111 in order to effect the interference fit and seal between the intermediate seal 127 and the roller shell 111. The sealing arrangement is further enhanced by utilisation of the second sealing element 139 which not only provides a barrier between the deflection seal 121 and the intermediate seal 127 but also serves to provide a gutter or channel between the deflection seal and intermediate seal which will divert any water away from the sealing engagement between the second sealing element 139 and the deflection seal. In addition on rotation of the second sealing element as a result of rotation of the roller shell 111 and thus the intermediate seal 127, the water collecting in that gutter will be -19centrifugally ejected through the space provided between the outer lip 125 of the deflection seal 121 and the intermediate seal 127. In addition the sealing action of the outer seal assembly is enhanced by the close spaced relationship between the intermediate portion of the shaft seal and the inner radial face of the intermediate seal.

The outer seal assembly 115 of the second embodiment provides a preassembled cartridge which when installed in a roller shell and on a shaft has improved sealing properties over the prior art.

The roller bearing seal assembly according to the first embodiment further 10 comprises the rear seal 119 which comprises an inner radial portion 145 which is frictionally received over the shaft 113. On application of the rear seal to the shaft 113 and to the roller shell 111 the outermost axial face of the inner portion (relative to the roller shell) bears against inner axial face of the bearing 117. The rear seal further comprises an outer radial portion 147 which extends radially 15 outwardly from the inner radial portion 145 and has an outer diameter such that its external radial surface is closely proximate the inner radial edge of the radial flange 114 of the roller shell. The inner edge of the outer radial portion (relative to the roller shell) is formed with a radial lip 149 which extends radially outwardly from the surface of the outer radial portion 147. In mounting the rear seal to the shaft 113 and the roller shell the radial lip 149 is located to innermost (relative to the roller shell) from radial flange 114 of the bearing shell 111. The close spacing of the outer radial portion 147 from the inner edge of the flange 114 of the roller provides a barrier which serves to resist the ingress of any water into the region of the bearing from within the body of the shell 111 both when the roller is stationary and when it is rotating.

In addition the radial lip 149 is configured to provide a sharp outer edge. The purpose of the sharp edge is to inhibit the collection of water droplets at the edge and to promote the shedding of water from the rear seal 119. In addition when the rear seal is in position the radial lip 149 is spaced sufficiently from the radial flange 114 of the roller shell such that even when the central longitudinal axis of the roller shell is inclined upwardly the outer edge is located outward of the adjacent edge of the radial flange 114. Therefore when water is shed from the radial lip it will fall clear of the inner edge of the flange 114.

It is a further feature of the embodiment that the roller shell 111 is provided with a breather aperture 155 at its end face which serves to allow for the passage of air into and out of the shell cavity to accommodate for pressure and temperature variations within the body of the roller shell as a result. The purpose of the breather aperture is to ensure that there is a substantial equalization of pressure 10 between the interior of the shell and the environment and to ensure that any air *flow that is induced as a result of an inequality between the interior and exterior is not required to pass through the roller bearing seal assembly. The breather aperture 155 is closed by a plug 157 which is formed of a rigid pervious material which is such that it will permit the passage of air through the breather aperture 155 but will resist the passage of water molecules water in a liquid or gaseous form) through the breather aperture 155. A suitable form of material which can be used in the plug can comprise a sintered glass or like ceramic material. Alternatively the material can comprise a plastics material. According to one example of material the pore size is of the order of 3 micron. As a result of the presence of the plug the flow of air into the roller shell as a result of a reduction in pressure within the shell will not result in water being drawn into the shell when the shell is in wet environment. In addition the selective filtering of water molecules from the air as it flows into the roller shell will reduce the likelihood of water collecting in the shell as a result of condensation.

According to an alternative embodiment of the invention the breather aperture of each of the above embodiments is closed by a plate rather than a plug. The plate is fixed to the external face of the shell to overlie the breather aperture where the plate is formed of a rigid pervious material which is such that it will permit the passage of air through the breather aperture but will resist the -21passage of water molecules water in a liquid or gaseous form) through the breather aperture.

It is a characteristic of the roller bearing seal according to the each of embodiments that the seal assembly the outer seal and rear seal) and the breather aperture closed by a plug or plate as described above are able to significantly resist the passage of water into an out of the body of the shell through the seal assembly even when subjected to relatively high pressure water :wash down. In this regard an example of a roller bearing seal according to the :i second embodiment was applied to each end of a roller shell which incorporated 10 a breather aperture having a plug according to the second embodiment and the roller shell was applied over a shaft. The complete assembly was then fully immersed in water for a period of time. At the conclusion of the period no water S:had entered the roller shell.

Furthermore, the compact nature of the outer seal assembly enables the location o 15 at which the shaft 13 is supported from a suitable support to be closer to the bearing 17 than has been the case with previous embodiments. This reduction spacing serves to reduce the bending moment between the mounting of the roller shaft to the support and the bearing. This has in turn enabled a reduction in the shaft size and allows for the utilisation of a constant diameter shaft rather than a stepped shaft.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that the scope of the present invention need not be restricted to the particular scope of the embodiment described above.

Claims (28)

1. A roller shell adapted to be supported from a shaft to be rotatable on the shaft wherein the shell is hollow and is formed with a central opening at each end wherein at least one end face accommodates a breather which comprises an aperture formed through the at least one end face to provide communication between the interior and exterior of the shell, said aperture being closed by a solid porous element. .:i 2. A roller shell as claimed at claim 1 wherein the solid porous element is pervious to air but is substantially impermeable by water.

3. A roller shell as claimed at claim 1 or 2 wherein the solid porous element is substantially impervious to water in both liquid and gaseous form.

4. A roller shell as claimed at any one of the preceding claims wherein the roller shell is supported from the shaft by a roller bearing seal assembly located at each central opening, each roller bearing seal assembly 15 comprising an outer seal assembly and a bearing, wherein the outer seal assembly comprises, a first annular member adapted to be non-rotatably supported on the shaft and which is located outermost, a second annular member adapted to be supported from the shell located closely adjacent the first annular member, the radial extent of the members being such that they overlap, wherein the outer seal assembly further comprises a resilient flexible sealing element supported on the first or second annular member and being in slidable contact with the opposed face of the other annular member. A roller shell as claimed at claim 4 wherein the sealing element defines a channel shaped surface between the first and second annular members which is directed radially outwardly. -23-

6. A roller shell as claimed at claim 4 or 5 wherein the outer edge of the sealing element comprises a first lip seal which is radially innermost and which is in sliding contact with the other annular member, the sealing element further comprising a second lip seal which is radially outermost and is in sliding contact with the other annular member and is deflected radially outwardly.

7. A roller shell as claimed at claim 6 wherein the first lip seal is in light S. sliding contact with the other annular member. o°

8. A roller shell as claimed at claim 4 or 5 wherein the outer edge of the 10 sealing element is formed as a flange which extends radially outward from the sealing element, said flange being in sliding sealing contact with the other annular member.

9. A roller shell as claimed at any one of claims 4 to 8 wherein the sealing element is supported on the second annular member.

10. A roller shell as claimed at any one of claims 4 to 9 wherein the second annular member has a flange at its inner edge.

11. A roller shell as claimed at claim 10 as dependant from claim 9 wherein the flange at least partially supports the sealing element.

12. A roller shell as claimed at any one of claims 4 to 11 wherein the sealing element is formed of formed from an elastomeric material or a material having elastomeric like properties.

13. A roller shell as claimed at any one of claims 4 to 12 wherein the second annular member is adapted to be sealingly engaged with the shell. -24-

14. A roller shell as claimed at claim 13 wherein the sealing engagement is provided by a resilient sealing medium supported from the second annular member. A roller shell as claimed at claim 14 wherein, the sealing medium is bonded to the outer radial face of the second annular member.

16. A roller shell as claimed at claim 13 or 14 wherein the sealing medium is formed from an elastomeric material or a material having elastomeric like properties. l. 0" 17. A roller shell as claimed at any one of claims 4 to 16 wherein the second annular member is formed as a composite member comprising a rigid annulus and a moulding supported by the rigid annulus.

18. A roller shell as claimed claim 17 as dependant from claim 14 wherein S the sealing medium is formed as an integral part of the moulding. ooooo

19. A roller shell as claimed claim 17 or 18 wherein the sealing element is o formed as an integral part of the moulding A roller shell as claimed at any one of claims 17 to 19 wherein the moulding is formed from an elastomeric material or a material having elastomeric like properties.

21. A roller shell as claimed at any one of claims 4 to 20 wherein the outer seal assembly further comprises a rigid shaft seal adapted to be non- rotatably supported on the shaft and located between the first annular member and the bearing; wherein the shaft seal comprises a first annular flange extending radially outwardly from the shaft into the space between the second annular member and the bearing, said shaft seal having an outer radial surface which is closely adjacent the inner radial face of the second annular member, said shaft seal being configured to frictionally engage the first annular member.

22. A roller shell as claimed at claim 21 wherein the shaft seal is formed of a substantially rigid plastics material.

23. A roller shell as claimed at claim 21 or 22 wherein the shaft seal supports the first annular member from the shaft.

24. A roller shell as claimed at any one of claims 21 to 23 wherein the outer radial surface comprises a second annular flange extending radially Doge outwardly from the shaft such that its outer periphery is located closely adjacent the inner radial face of the second annular member. A roller shell as claimed at any one of claims 21 to 24 wherein the outer radial surface of the shaft seal and inner radial face of the second annular S. member have an axial extent. •e

26. An roller shell as claimed at any one of claims 22 to 26 as dependant 15 from claim 7 or claim 8 wherein the flange at the inner edge of the second annular member provides the inner radial face of the second annular member.

27. A roller shell as claimed at any one of claims 4 to 26 wherein the roller bearing seal assembly further comprises an inner seal, said inner seal being intended to be located adjacent the innermost face of the bearing, said inner seal adapted to be non-rotatably supported from the shaft proximate the inner edge of the annular flange of the roller shell, the diameter of the outer radial face of the inner seal being such that the outer radial face is in closely spaced relation to the inner edge when the inner seal is in position in a roller shell, the axial dimension of the outer radial face of the inner seal being such that the outer radial face extends to either side of the inner edge when the inner seal is in position in a roller -26- shell and the outer radial face is formed at the inner end of the inner seal relative to the roller shell with a first lip which is spaced inwardly relative to the roller shell, from the inner edge when the inner seal is in position in a roller shell.

28. A roller shell as claimed at claim 27 wherein the outer radial face is substantially parallel to the central axis.

29. A roller shell as claimed at claim 27 wherein the outer radial face is convergent in the direction of the first lip

30. A roller shell as claimed at claim 27, or 28, or 29 wherein the outer end 10 of the outer radial face relative to the roller shell, is formed with a second O lip which is spaced outwardly, relative to the roller shell, from the inner ~edge when the inner seal is in position in the roller shell whereby the outer radial face has a generally channel shaped configuration defined by the first and second lip and the portion of the outer radial face between i 15 the first and second lips.

31. A roller shell as claimed at claim 30 wherein the second lip is dimensioned to be in sliding sealing relationship with the outer radial portion of the bearing when the inner seal is in position in a roller shell.

32. A roller shell as claimed at claim 30 or 31 wherein the portion of the outer radial face between the first and second lips is convergent in the direction from the second lip to the first lip.

33. A roller shell as claimed at any one of claims 27 to 32 wherein the first lip is formed with a sharp outer edge.

34. A roller shell as claimed at any one of claims 27 to 33 wherein the first lip is spaced outwardly from the inner edge a sufficient distance such that vertical plane containing the lower most extent of the first lip is spaced -27- inwardly, relative to the roller shell, from the vertical plane containing the lowermost extent of the rotational path of the inner edge when the inner seal is in position in a roller shell and the roller shell is in use. A roller shell substantially as herein described Dated this TWENTY SECOND day of DECEMBER 1999. PROK GROUP LIMITED Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant(s) o C *o C *C C