GB2228298A

GB2228298A - Bearing seal

Info

Publication number: GB2228298A
Application number: GB8902046A
Authority: GB
Inventors: Alan Hodgson
Original assignee: Huwood Ltd
Current assignee: Huwood Ltd
Priority date: 1989-01-31
Filing date: 1989-01-31
Publication date: 1990-08-22
Also published as: AU4950590A; GB8902046D0; ZA90636B; CN1044703A; WO1990008906A1

Abstract

The present invention relates to a sealed pivotal bearing assembly (1) comprising a pivot pin (4) mounted in an annular bearing member (7, 3) for pivotal displacement through a limited angle relative thereto. An annular sealing means in the form of a resiliently torsionally deformable collar (13) has first and second annular portion (16, 14) fixedly secured in fluid tight manner to respective ones of the bearing member (7, 3) and the pivot pin (4) thereby to seal across a bearing interface (9) therebetween, so that in use of the assembly, the pivot pin may be pivoted relative to the bearing member (7, 3) whilst maintaining a fluid-tight seal around the bearing interface (9) therebetween.

Description

BEARING SEAL The present invention relates to bearing seals and in particular to seals for pivotal bearings.

Various machinery which includes pivotal bearings, as for example in conveyor drive chains, especially those used for bulk material as for example in various mining operations, is exposed to particularly severe operating conditions including exposure to contamination with extraneous particulate material such as coal dust in the case of coal mining machinery. Conventional conveyor drive chains in particular include a large number of bearing surfaces since each link in the chain is connected to neighbouring links by two pivot pins, and each of these bearing surfaces is exposed to ingress of foreign, more or less abrasive, matter and hence to wear resulting in loss of performance and eventual failure of the chain.

Such drive chains are moreover subjected to relatively high loadings and tensions so that the ingress of foreign matter to the bearing surfaces results in particularly rapid wear and pin hole elongation which leads to rapid slackening of the chain and in turn to further problems such as chain disengagement from drive sprockets etc., due to the limited stretch of the known chains. A further problem that can arise with twin or parallel drive chains in the case of differential wear of the pins and/or bushes is that of loss of alignment of cross flights or paddles mounted across the chains, which are normally required to be maintained square with respect to the drive chains for proper entrainment of bulk material etc.

It is an object of the present invention to avoid or minimise one or more of the above disadvantages.

The present invention provides a sealed pivotal bearing assembly comprising a pivot pin or shaft mounted in an annular bearing member for pivotal displacement through a limited angle relative thereto, an annular sealing means in the form of a resiliently torsionally deformable collar means having first and second annular portions fixedly secured in substantially fluid tight manner, directly or indirectly to respective ones of said bearing member and said pivot pin or shaft thereby to seal across a bearing interface therebetween, whereby in use of the assembly said pivot pin or shaft may be pivotally displaced relative to said bearing member whilst maintaining a substantially fluid-tight seal around the bearing interface therebetween.

With a drive chain of the prevent invention wearing of bearing surfaces with the resulting consequences of hole elongation, chain slackening and accelerated further wear due to the ingress of foreign matter between the relatively pivoting parts, are eliminated by providing a bearing seal without relatively moving interfaces with the relatively pivoting parts, passage of material around the seal being substantially completely avoided - or at least to a significantly greater degree than is possible with conventional more or less freely rotatable seals. Instead the present invention relies on the inherent torsional deformability of the sealing means to maintain flexibility of the drive chain during its travel.

The sealing means may be made of any suitable resiliently torsionally deformable material including polymeric materials and especially natural or synthetic rubber.

The sealing means may be fixedly secured to the pivot pins or shafts and to the bearing members by any one or more of mechanical interlocking, interference fit therebetween, and by means of the use of suitable adhesives adapted for bonding between the bush material e.g. rubber and the pin material e.g. steel. Any suitable form of mechanical interlocking may be employed including various non-circular section pins and bushes e.g. polygonal, including splined, as well as substantially circular but with a suitable keyway for insertion of a key between the pin and bush, the interlocking surfaces being a close fit such as to prevent passage of material therebetween during pivoting in use of the pivotal bearing.

It will also be appreciated that either similar or different means may be utilised for fixed securing between the sealing means and the bearing members on the one hand and between the sealing means and the pivot pins or shafts on the other hand.

It will also be appreciated that various forms of sealing means and, in particular, different arrangements for securing thereof, may be used according to the shape and configuration of the pivot pins or shafts and the bearing members (or other parts fixedly connected thereto).

Thus in either case the annular sealing collar may have an axial end face or a radially, inward or outward (as appropriate), surface secured to the respective one of the relatively moving parts.

As noted above the problem of pivotal bearing wear is particularly severe in conveying apparatus and thus in a preferred aspect the present invention provides a drive chain having a pivotal bearing assembly seal of the invention.

Any suitable form of chain links may be used in a drive chain of the invention including on the one hand chain links which are all substantially similar and on the other hand alternating main links and connecting links. Also there may be used sealing means at all the interfaces between links and pins, or only at some of them, with the pins being non-rotatably secured e.g. by clamping, welding, etc., at the others.

As indicated above the present invention extends to various forms of conveyor drive chain including drive chains having flight bars and/or conveyor buckets connected thereto and systems having twin or parallel drive chains with flight bars or buckets connected thereto.

In the latter case the maintenance of chain tension is particularly valuable because it helps to maintain the flight bars or paddles square relative to the length of the chain.

In a further aspect the present invention extends to a conveyor suitable for use in the conveying of bulk material and having a conveyor drive chain with pivotal bearing seals of the invention.

Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawings in which: Fig. 1 is a partially cut away side elevation of part of a conveyor chain with bearing assembly seals of the present invention; Fig. 2 is a longitudinal horizontal section through the chain of Fig. 1; and Fig. 3 is a corresponding view of a modified embodiment.

Fig. 1 shows a drive chain 1, comprising a plurality of main chain links to interconnected by connecting links 3, the connecting links and main chain links being pivotally connected to each other by pivot pins 4.

As may be seen more clearly in Fig. 2, the main chain links 2 are fixedly secured, e.g. by welding 5 to the pivot pins 4 at their outermost ends 6 so as to be nonrotatable relative thereto. The connecting links 3 are provided with annular bearing bushes 7 at each end 8 for pivotally supporting 9 the pivot pins 4. An annular recess 10 is provided in the outer side face 11 of the connecting link 3 at each end 12 of the bearing bush 7.

In each annular recess 10 is disposed a bearing seal in the form of an annular collar 13 of a resiliently deformable material such as rubber. The radially inward surface 14 of the collar 13 is fixedly secured to the outer cylindrical surface 15 of the pivot pin 4, whilst the radially outward surface 16 of the collar 13 is fixedly secured to the connecting link 3 at the outer cylindrical face 17 of the annular recess 10. The collar may be secured to the pin and connecting link by any suitable means, for example a metal to rubber adhesive.

Thus each of the radially outward and radially inward surfaces 16, 14 of the collar 13 are secured to the connecting link 3 and pivot pin 4, respectively, against rotation relative thereto. Nevertheless the connecting link 3 is able to undergo a limited angular pivotal displacement relative to the pivot pin 4 and hence to the main chain link to secured thereto, through torsional deformation of the collar 13 between its radially outward and radially inward surfaces 16, 14, whilst providing a complete seal around the bearing bush end 12. In this way, any required lubricant provided between the pivot pin 4 and the bearing bush 7 is securely contained against escape whilst ingress of any foreign material to the bearing is similarly prevented.

Fig. 3 shows a generally similar drive chain in which like parts corresponding to those in the embodiment of Figs. 1 and 2 have been indicated by like reference numbers. In this case though it may be noted that the axially inner and outer end faces 18, 19 of the collar seal 13 are secured to respective opposed side faces 20, 21 of the annular recess 10 of the connecting link 3, and the main connecting link 2. This arrangement also provides a complete sealing in of the bearing bush 7 where the pivot pin 4 is secured to the main chain link 2 by a fluid tight joint 5 formed, for example by welding.

In this case, the axial end faces 18, 19 of the collar seal 13 are secured against movement relative to the connecting link and main link 3, 2 respectively, relative pivotal movement between these two parts being permitted via torsional deformation of the collar seal 13 between the axial end faces 18, 19 thereof.

Thus the present invention provides a particularly secure bearing seal in a relatively simple and economic manner.

Further features of the invention will appear from Fig. 4 to 8 of the accompanying drawings in which like parts corresponding to those in the abovedescribed embodiments are identified by like reference numerals.

Figs. 4a, b, c show sections of seals 13 which are provided with various forms of first and second, more or less lightweight, protective metal pressing elements 22, 23 fixedly secured to opposite side faces 14, 16 or 18, 19 of the resiliently deformable main body 24 of the seal 13, and fixedly securable in turn to respective ones of the relatively movable bearing member and pivot pin or shaft (not shown). As may be seen in Figs. 4b and 4c moreover either or both of the protecting elements 22, 23 may extend around, though not secured to, other faces 25 of the main body 24 of the seal 13, which faces 25 are subjected to deformation upon relative displacement of said opposite side faces 14, 16 or 18, 19 secured in use (via the protective elements 22, 23) to the bearing member and pivot pin or shaft.

It will be appreciated that the torsion seals of the invention may be used in a wide variety of pin-bearing member chains and a number of different types are shown in Figs. 5 to 8. In addition various suitable forms of bearing may be used including not only plain bush elements 7, but also roller bearings e.g. needle bearings or ball bearings 26 as shown in Fig. 5.

In order, inter alia, to optimise the performance of the torsion seals of the invention,they may conveniently be formed and arranged to operate within predetermined angular displacement limits e.g. up 10 , up to 200, or up to 300. In such cases the pivot pin or shaft and the bearing member are desirably provided with interengaging stops for limiting their relative angular displacement, for example, as shown in Figs. 5 and 6 wherein the main chain links 2 are provided with angularly spaced apart opposed stops 27, 28 projecting generally radially of the pivot pin 4 rotational axis X - X and the connecting links 3 are provided with a single stop 29 disposed between the opposed stops 27, 28 for interengagement with one or other thereof at the limits of the predetermined relative angular displacement of the links 2, 3. In this way overstressing and possible irreversible damage to the torsion seals 13 may be prevented.

Claims

1. A sealed pivotal bearing assembly comprising a pivot pin or shaft mounted in an annular bearing member for pivotal displacement through a limited angle relative thereto, and annular sealing means in the form of a resiliently torsionally deformable collar means having first and second annular portions fixedly secured in substantially fluid tight manner, directly or indirectly, to respective ones of said bearing member and said pivot pin or shaft thereby to seal across a bearing interface therebetween whereby in use of the assembly said pivot pin or shaft may be pivotally displaced relative to said bearing member whilst maintaining a substantially fluid-tight seal around the bearing interface therebetween.

2. An assembly according to claim 1 wherein said annular portions are disposed at respective axial end faces of the collar.

3. An assembly according to claim 1 wherein said annular portions are disposed at radially inward and radially outward faces of the collar.

4. An assembly according to claim 1 wherein one said annular portion is disposed at an axial end face of the collar, and another said annular portion is disposed at a radially inward or outward face of the collar.

5. An assembly as claimed in any one of claims 1 to 4 wherein said pivot pin or shaft is fixedly secured to said sealing means by means of mechanical interlocking therewith.

6. An assembly as claimed in any one of claims 1 to 5 wherein said pivot pin or shaft and sealing means are relatively dimensioned so that said pin or shaft is an interference fit in said sealing means so as to secure said pin means non-rotatably in said sealing means.

7. An assembly as claimed in any one of claims 1 to 6 wherein said pivot pin or shaft is fixedly secured to said sealing means by an adhesive.

8. An assembly as claimed in any one of claims 1 to 7 wherein said sealing means is fixedly secured in said bearing member by means of mechanical interlocking therewith.

9. An assembly as claimed in any of claims 5 to 8 wherein said sealing means and bearing member are relatively dimensioned so that said sealing means is an interference fit in said bearing member so as to secure said sealing means non-rotatably in said bearing member.

10. An assembly as claimed in any one of claims 5 to 9 wherein said sealing means is non-rotatably secured in said bearing member by means of an adhesive.

11. An assembly as claimed in claim 5 or claim 8 wherein said mechanical interlocking is effected by the use of complementary non-circular cross-sectional shapes.

12. An assembly as claimed in claim 11 wherein is used a polygonal cross-sectional shape.

13. An assembly as claimed in any one of claims 1 to 12 wherein said sealing means is of a polymeric material.

14. An assembly as claimed in claim 13 wherein said sealing means is of natural or synethic rubber.

15. An assembly according to any one of claims 1 to 14 wherein said assembly comprises part of a drive chain comprising a plurality of chain links interconnected by pivot pins mounted in annular bearing member portions of at least some of said links.

16. An assembly as claimed in claim 15 wherein said chain links comprise main links interconnected by connecting links.

17. An assembly as claimed in claim 15 wherein sub stantially all the chain links of said chain are substantially similar and at least one end of each of said links has a said annular bearing member portion.

18. An assembly as claimed in any one of claims 15 to 17 wherein each end of each of said chain links has a said annular bearing member portion.

19. An assembly as claimed in any one of claims 15 to 18 wherein said sealing means are secured to said pivot pins or shafts and links so that in the undeformed conditions of the sealing means, adjoining links extend from each other at an angle of less than 180 degrees.

20. An assembly as claimed in any one of claims 15 to 19 wherein at least some of said links have flight bars and/or conveyor buckets connected thereto.

21. A conveyor having a drive chain with a bearing assembly according to any one of claims 15 to 20.