GB2514755A

GB2514755A - A Chain

Info

Publication number: GB2514755A
Application number: GB201305228A
Authority: GB
Inventors: Christopher David Bishop
Original assignee: Renold PLC
Current assignee: Renold PLC
Priority date: 2013-03-21
Filing date: 2013-03-21
Publication date: 2014-12-10
Also published as: GB201305228D0

Abstract

A chain comprising a plurality of axially spaced tubular rollers 3, each roller being connected to first and second axially adjacent rollers by first and second links 4, 5, wherein an articulation element 6 is received within each roller 3 that defines an arcuate bearing surface (7, fig 4) on which the roller 3 is rotatably supported and the first and second links 4, 5 are pivotally mounted to the articulation element 6, for rotation relative to the articulation element 6 by first and second pivot members 18, 19 which are rotatably supported by the articulation element 6 and wherein the articulation element 6 comprises an intermediary section 21 provided between the first and second pivot members 18, 19 that spaces the first and second pivot members 18, 19 apart such that they are not in rolling contact with each other. Alternative articulated members are shown in other embodiments.

Description

A CHAIN

The present invention relates to a double articulation roller chain of the kind that is used, generally in combination with a sprocket, in drive or power transmission mechanisms etc. A conventional single articulation roller bush chain for use in such applications comprises pairs of laterally opposed inner link plates interleaved with pairs of laterally opposed outer link plates along the length of the chain. Each pair of opposed inner link plates is connected together by a pair of spaced cylindrical bushes that are received in a friction fit in apertures in the inner links. Each outer link plate extends in parallel to the inner link plates and overlaps the adjacent ends of neighbouring inner links. The inner and outer link plates are interconnected on opposite sides of the chain by pins that pass through the bushes and aligned apertures in the outer link plates on both sides of the chain. The pin is fixed at each end to the outer link plates but is pivotal with respect to the inner link plates. A freely rotatable cylindrical roller is supported on each bush.

A known double articulation chain, commonly referred to as a Dairy Case Conveyor Chain', comprises pairs of laterally opposed link plates that are spaced in the axial direction by a rectangular spacer block. Each of the axially adjacent ends of the links of each pair are pivotally mounted to a respective end of the spacer block by a pin that pass through the end of the link and into a bore in the respective end of the spacer block. However, this arrangement is not suitable for use in a double articulation roller chain. In addition, it requires a complex sprocket arrangement whereby alternating teeth of the sprocket are missing, so as to allow the passage of the spacer block around the sprocket.

International patent application no. PCT/GB9S/01873 (Renold Plc), discloses a roller bush chain comprising a plurality of spaced rollers, each rotatably supported by a respective cylindrical bush. Each bush is interconnected by rigid elongate C-shaped wire links arranged such that axially adjacent links are provided on alternating lateral sides of the chain. The wire links have end portions that are each rotatably received in a respective bush. Adjacent end portions in a given bush are interconnected such that the wire links are rotatable relative to each other. In one embodiment (see Figure 6 of the International application), two end portions of axially adjacent wire links are received within a single bush and are arranged in rolling contact with each other. This suffers from the problem in that the end portions of the wire links suffer from high wear due to their rolling contact. In addition, when the chain is under tension, tensile forces within the chain are carried by the end portions of the wire links which causes further wear on the links.

Furthermore, in such a roller chain, the rollers are used to decrease frictional engagement with the sprocket. In a conveyor chain the roller is also used to carry loads and/or to guide the chain over a long span, running on a rail or other surface. In either of these cases, it is undesirable for the roller to be prevented from rotating. In the above known arrangement, when the chain is under tension, the wire links try to rotate past each other and move away from each other in the axial direction. This causes the bush to bear against the inner surface of the roller which acts to clamp the roller, thereby causing the roller to stick. Furthermore, this arrangement is limited to a laterally alternating arrangement of C-shaped wire links.

It is an object of the present invention to provide a double articulation roller chain that has low wear during use. It is another object of the present invention to provide a double articulation roller chain that is able to bear a tensile load, without preventing the rollers of the chain from rotating. It is another object of the present invention to provide a double articulation roller chain that is resistant to twisting and has relatively high lateral stiffness. It is another object of the present invention to provide a double articulation roller chain that doesn't require lubrication, or only requires minimal lubrication. It is another object of the present invention to provide a relatively inexpensive double articulation roller chain. It is another object of the present invention to provide a double articulation roller chain that can have a flexible configuration.

According to a first aspect of the present invention there is provided a chain defining a longitudinal axis along its length, the chain comprising a plurality of tubular rollers spaced in the direction of the longitudinal axis of the chain, each roller being connected to first and second axially adjacent rollers, disposed either side of the roller, by first and second links respectively, wherein an articulation element is received within each roller that defines an arcuate bearing surface on which an inner surface of the roller is rotatably supported and the first and second links are pivotally mounted to the articulation element, for rotation relative to the articulation element about first and second spaced axes, by first and second pivot members respectively which are rotatably supported by the articulation element and wherein the articulation element comprises an intermediary section provided between the first and second pivot members that spaces the first and second pivot members apart such that they are not in rolling contact with each other.

In this arrangement, during use circumferentially adjacent sprocket teeth pass either side of each roller. Accordingly, the chain provides a double articulation chain, since double articulation takes place within the confines of a single sprocket tooth gap.

Since the first and second pivot members are rotatably supported by the articulation element and the intermediary section of the articulation element spaces the first and second pivot members, the pivot members aren't in rolling contact with each other and so don't act to wear each other away during use. In addition, the articulation element can be made of a low friction material which requires no, or minimal lubrication. Therefore the chain is provides a low maintenance chain and doesn't require lubrication, or only requires minimal lubrication.

Furthermore the links, articulation elements and pivot members replace the outer links and the bushes of conventional roller bush chains. Accordingly, the arrangement provides for a relatively low cost and simple double articulation chain that uses significantly less material than a conventional roller bush chain.

In addition, since the links are pivotally mounted to the articulation element, the links can pivot relative to each other, without requiring the articulation element to comprise two separate sections that are rotatable relative to each other, with each link attached to a separate section of the articulation element, in order to provide this. This is advantageous in that it allows the first and second pivot members to be connected by the intermediary section of the articulation element. The intermediary section of each articulation element facilitates the transmission of tensile forces in the chain by each articulation element, as opposed to by the rollers. This prevents the rollers from sticking/slipping, thereby allowing efficient operation of the chain under tensile loads. In addition, the intermediary section also allows the articulation elements to be arranged so as to increase the resistance of the chain to twisting about the longitudinal axis of the chain as well as to increase the lateral stiffness of chain, i.e. in a direction transverse to the longitudinal axis of the chain.

The first and second axes may be spaced apart in a radial and/or circumferential direction of the articulation element. Preferably the first and second axes are diametrically opposed about a longitudinal axis of the articulation element.

The first and second pivot members may be rotatably supported, at least in part, by the intermediary section of the articulation element.

Preferably the first and second pivot members are received within first and second bores in the articulation element, defined by respective first and second inner surfaces of the articulation element and respective outer surfaces of the first and second pivot members are rotatably supported by said first and second inner surfaces of the articulation element. The outer surfaces of the first and second pivot members may be in rolling contact with said inner surfaces. Alternatively, they may be in rolling contact with bearing elements provided between the pivot members and said inner surfaces.

Preferably the respective outer surfaces of the first and second pivot members are substantially arcuate. Preferably the first inner surface of the articulation element substantially extends around the circumference of the first pivot member and/or the second inner surface of the articulation element substantially extends around the circumference of the second pivot member.

Preferably the inner surface of the articulation element that defines the first bore and/or the inner surface of the articulation element that defines the second bore is formed from a low friction material. Examples of suitable low frication materials include sintered materials with oil impregnation, filled polymers, composite materials, steel with PTFE coating, etc. Preferably the intermediary section is arranged so as to constrain movement of the arcuate bearing surface towards the inner surface of the roller when the chain is put under tension. Preferably the intermediary section is arranged so as to constrain movement of the arcuate bearing surface towards the inner surface of the roller when forces on the chain act to move the first and second pivot members away from each other. Preferably said movement is substantially prevented.

This is advantageous in that tensile forces on chain, that pass from the first and second pivot members into the articulation element, are resisted by the intermediary section of the articulation element. The intermediary section prevents the tensile forces from causing the bearing surface of the articulation element to clamp against the inner surface of the roller. This prevents the rollers from sticking/slipping, thereby allowing efficient operation of the chain under tensile loads. Accordingly, this allows the rollers to rotate even when the chain is under tensile load.

Preferably the arcuate bearing surface comprises first and second sections located at different circumferential positions relative to the inner surface of the roller and the intermediary section of the articulation element attaches the first and second sections together such that movement of the first and second sections towards the inner surface of the roller is constrained. Preferably said movement is substantially prevented. Preferably the intermediary section of the articulation element attaches the first and second circumferential sections together such that the first and second sections are fixed relative to each other.

Preferably the first and second sections of the bearing surface are diametrically opposed about a longitudinal axis of the articulation element.

Preferably the intermediary section extends from the first section to the second section in a direction substantially parallel to an axis which passes through respective first and second longitudinal axes of the first and second bores. Preferably said direction is substantially perpendicular to said first and second longitudinal axes of the first and second bores.

Preferably the intermediary section is integrally formed with the first and second circumferential sections of the bearing surface. This is advantageous in that it provides a 1 0 structurally strong, relative simple and cheap structure (as compared to if the intermediary section was formed separately and attached to the first and second surfaces, e.g. by welding).

Preferably the intermediary section attaches the first and second pivot members together such that movement of the first and second pivot members towards the inner surface of the roller is constrained. Preferably said movement is substantially prevented. Preferably the intermediary section of the articulation element fixes the first and second pivot members to each other. Preferably the first and second pivot members are diametrically opposed about a central axis of the articulation element. This is advantageous in that when the chain is under tension, the tensile force propagates through the articulation element and not through the rollers. This prevents the rollers from sticking/slipping, thereby allowing efficient operation of the chain under tensile loads. In addition, it ensures accurate alignment of the rollers with the sprocket teeth.

Preferably the intermediary section attaches the first and second inner surfaces of the articulation element that define the first and second bores. Preferably the intermediary section attaches sections of the first and second inner surfaces that are adjacent to each other.

Preferably the intermediary section attaches sections of the first and second inner surfaces that are adjacent to each other in a direction substantially parallel to an axis which passes through respective centres of the first and second bores.

Preferably the bearing surface of the articulation element is complementary to the inner surface of the roller.

The bearing surface may be a continuous surface. In this case, the first and second sections of the bearing surface are different circumferential sections of the same surface.

Alternatively, the bearing surface may comprise a plurality of discrete sections, spaced apart in the circumferential direction of the inner surface of the roller. This is advantageous in that it reduces the contact surface area between the bearing surface of the articulation element and the inner surface of roller, or a bearing element provided between the two surfaces (as compared to if the bearing surface was a continuous surface in contact with the inner surface of the roller/bearing element). This reduces friction between said surfaces, thereby providing a more efficient chain and preventing the rollers from sticking. In addition, the plurality of circumferentially spaced surfaces of bearing surface supports roller across its inner circumference so as to prevent it from flattening.

The bearing surface preferably comprises three or four discrete sections, spaced apart in the circumferential direction of the inner surface of the roller. Preferably said discrete sections are uniformly spaced in the circumferential direction of the inner surface of the roller.

This provides an efficient arrangement that uses relatively few sections of the bearing surface, while supporting the roller across its inner circumference so as to prevent it from flattening.

In this case, the first and second sections of the bearing surface are discrete sections of the bearing surface, spaced apart in the circumferential direction of the inner surface of the roller.

The articulation element may have a cross sectional shape that is generally circular, or a section of a circle. The articulation element may be a cylinder, a section of cylinder or a plurality of sections of a cylinder.

Preferably at least one of said sections of the bearing surface has a radius of curvature that is substantially less than the radius of curvature of the inner surface of the roller.

Preferably each of said sections of the bearing surface has a radius of curvature that is substantially less than the radius of curvature of the inner surface of the roller.

The articulation element may comprise a first pivot member support, which has an inner surface that is complementary to an outer surface of the first pivot member and rotatably supports the first pivot member. An outer surface of the first pivot member support may form the, or a section of, the bearing surface of the articulation element. Alternatively, the first pivot member support may comprise a bearing element, such as a roller, that is rotatably supported on an outer surface of the first pivot member support and an outer surface of the bearing element may form the, or a section of, the bearing surface of the articulation element.

In this case, the articulation element preferably comprises first and second side plates, disposed on opposed lateral sides of the longitudinal axis of the chain, each provided with a first bore defined by respective inner surfaces of the plates and the first pivot member support passes through said bores and is supported by said inner surfaces. Preferably the first pivot member support is rotationally fixed within said bores. This may be by a friction fit or welding, for example. The first pivot member support preferably comprises a generally cylindrical sleeve.

Since the, or a section of, the bearing surface is formed by the first pivot member support, or the bearing element, this saves material, thereby reducing cost and weight. In addition, it allows the, or part of the, articulation element to be formed from conventional, readily available bushes and/or rollers, thereby lowering cost of manufacture.

Where the bearing surface comprises a plurality of discrete sections, spaced apart in 1 0 the circumferential direction of the inner surface of the roller, the articulation element may comprise a second said pivot member support circumferentially spaced from the first pivot member support in the circumferential direction of the inner surface of the roller.

Preferably the second pivot member support is diametrically opposed to the first pivot member support about a longitudinal axis of the articulation element.

In this case, the first and second side plates of the articulation element may each be provided with a second said bore, circumferentially spaced from the first bore in the circumferential direction of the inner surface of the roller and the second pivot support member passes through said bores and is supported by inner surfaces of the articulation element that define said second bores. Preferably the second bores are diametrically opposed to the first bores about a longitudinal axis of the articulation element. Preferably the second pivot member support is rotationally fixed within said second bores.

Preferably, for each of the first and second plates, the inner surfaces of the plate that define said first and second bores are attached to each other by the plate. Preferably, for each of the first and second plates, the first and second pivot member supports are connected by the plate. In this case, the plate preferably forms the intermediary section of the articulation element. Accordingly, the first and second plates may form the intermediary section and the pivot member supports may form the bearing surface, or a section of the bearing surface, of the articulation element. This is advantageous in that it allows a conventional, readily available, chain link plate, bushes and/or rollers to be used as the articulation element, thereby lowering cost of manufacture.

The articulation element may comprise a third said pivot member support disposed, in the circumferential direction of the inner surface of the roller, between the first and second pivot member supports. In this case, the first and second side plates of the articulation element may each be provided with a third said bore, disposed, in the circumferential direction of the inner surface of the roller, between the first and second bores.

In this case, the third pivot member support may not house a pivot member. The use of a redundant third pivot member support in this way is advantageous in that allows conventional, readily available, chain link plates and/or sections of chain link plates and bushes/rollers to be used as the articulation element, thereby lowering cost of manufacture.

Preferably the first, second and third pivot member supports are uniformly spaced in the circumferential direction of the inner surface of the roller. This provides an efficient arrangement that uses relatively few pivot support members, while supporting the roller across its inner circumference so as to prevent it from flattening.

The first and second pivot member supports may form a first pair of pivot member supports and the articulation element may comprise a second said pair of first and second pivot member supports wherein in the first pair the first pivot member support is diametrically opposed to the second pivot member support about a first axis and in the second pair the first pivot member support is diametrically opposed to the second pivot member support about a second axis and said first and second axes are substantially perpendicular to each other. This is advantageous in that it allows a pair of conventional, readily available, chain link plates, bushes and/or rollers to be used as the articulation element, thereby lowering cost of manufacture.

In this case, preferably the first and second bores in the first and second side plates of the articulation element form a first pair of bores and the first and second side plates are provided with a second said pair of said first and second bores, the first pair the first bore is diametrically opposed to the second bore about a first axis and the second pair the first bore support is diametrically opposed to the second bore about a second axis and said first and second axes are substantially perpendicular to each other and the first and second pairs of pivot member supports passes through the first and second pairs of said bores and are supported by the inner surfaces of the articulation element that define said bores. Preferably said pivot member supports are rotationally fixed within the bores in which they pass through.

In this case, the second pair of pivot member supports may not house a pivot member.

The use of a redundant second pair of pivot member supports in this way is advantageous in that allows conventional, readily available, chain link plates and/or sections of chain link plates and bushes/rollers to be used as the articulation element, thereby lowering cost of manufacture.

The roller may be rotatably supported on the articulation element either directly, with the bearing surface of the articulation element in contact with the inner surface of the roller.

Alternatively, an intermediate member may be provided between the bearing surface of the articulation element and the inner surface of the roller.

The intermediate member may be a bearing element. Preferably the bearing element is a rolling element bearing, for example a needle bearing. This is advantageous in that it prevents stick/slip of the roller due to friction between the bearing surface of the articulation element and the inner surface of the roller.

Alternatively, or additionally, the intermediate member may be a ring. For example a steel ring. This is advantageous in that the ring acts to further prevent tensile forces begin transmitted from the articulation element to the roller, thereby preventing stick/slip of roller when the chain is under tension.

The first and/or second pivot members may be generally cylindrical. A circumferential section of the first and/or second pivot members may be in rolling contact with the intermediary member.

Preferably the first and second links are rotationally fixed relative to the first and second pivot members respectively.

The first and second links may be provided on the same lateral side of the chain.

Alternatively, the first and second links may be provided on opposite lateral sides of the chain.

In this case, the articulation element preferably extends between laterally opposed surfaces of the first and second links and supports the first and second links in the lateral direction.

This is advantageous in that the articulation element acts to resist lateral forces exerted on the chain, as well as twisting of the chain about its longitudinal axis. Accordingly, this provides a double articulation roller chain that is resistant to twisting and has relatively high lateral stiffness.

Each roller may also be connected to the first and/or second axially adjacent rollers by a second said first and/or second link respectively, that is laterally opposed to the first and/or second link respectively and is also rotatably mounted to the articulation element by the first and/or second pivot member respectively.

The first and/or second pivot member may extend in the lateral direction from at least one side face of the articulation element for attachment to a roller or attachment block.

Preferably the first and/or second pivot member extends in the lateral direction from both side faces of the articulation element.

Preferably axially adjacent ends of the first and second links are curved so as to allow relative rotation between said ends, as the links rotate about the first and second pivot members respectively.

All of the features described herein may be combined with any of the above aspects, in any combination.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows an exploded view of a section of a conventional roller bush chain; Figure 2 shows a plan elevational view of a section of a known double articulation chain, commonly referred to as a Dairy Case Conveyor Chain'; Figure 3 shows a perspective view of a section of a chain according to a first embodiment of the invention; Figure 4 shows an exploded perspective view of the section of chain shown in Figure 3, with a pair of pins of the chain removed for illustrative purposes; Figure 5 shows a front elevational view of the chain shown in Figures 3 and 4, with rollers of the chain removed for illustrative purposes; Figure 6 shows a plan elevational view of the section of chain shown in Figures 3 and 4, with rollers of the chain removed for illustrative purposes; Figure 7 shows a cross-sectional view taken along the axis C-C' in Figure 6; Figure 8 shows a front elevational view of a section of a chain according to a second embodiment of the invention, where a section of links of the chain, and a side face of a roller and articulation element of the chain have been removed for illustrative purposes; Figure 9 shows a plan elevational view of the section of chain shown in Figure 8; Figure 10 shows a front elevational view of a section of a chain according to a third embodiment of the invention, where a section of links of the chain, and a side face of a roller and articulation element of the chain have been removed for illustrative purposes; Figure 11 shows a plan elevational view of the section of chain shown in Figure 10; Figure 12 shows a front elevational view of a section of a chain according to a fourth embodiment of the invention; Figure 13 shows a plan elevational view of the section of chain shown in Figure 12; Figure 14 shows a front elevational view of a section of a chain according to a fifth embodiment of the invention; Figure 15 shows a plan elevational view of the section of chain shown in Figure 14; Figure 16 shows a front elevational view of a section of a chain according to a sixth embodiment of the invention; Figure 17 shows a plan elevational view of the section of chain shown in Figure 16; Figure 18 shows a cross-sectional view corresponding to that of Figure 7 but of a chain according to a seventh embodiment of the invention; Figure 19 shows a partial cross-sectional view, partial plan elevational view of the section of chain shown in Figure 18, taken along the line 400 in Figure 18; Figure 20 shows a front elevational view of a section of a chain according to an eighth embodiment of the invention; Figure 21 shows a plan elevational view of the section of chain shown in Figure 20; Figure 22 shows a plan elevational view of a modified section of the chain shown in Figure 20, and Figure 23 a cross-sectional view corresponding to that of Figure 18 but of a chain according to a ninth embodiment of the invention.

Referring now to the drawings, figure 1 shows the components of a conventional roller bush chain: rollers 101, bushes 102, pins 103, inner link plates 104 and outer link plates 105.

Such a chain has been described in the introductory part of this document.

Figure 2 shows the components of a section of a known double articulation chain, commonly referred to as a Dairy Case Conveyor Chain': pins 203, link plates 204, spacer block 206 and bores 207. Such a chain has been described in the introductory part of this document.

Referring to Figures 3 to 7 there is shown a longitudinal section of a double articulation chain 1 according to a first embodiment of the invention. The chain 1 defines a longitudinal axis 2 along its length. The chain 1 comprises a plurality of rollers 3 spaced in the direction of the longitudinal axis 2 of the chain. 1 An articulation element 6 is received within each roller 3 and rotatably supports the roller 3, for rotation about a roller axis 10. Each roller 3 is respectively connected to first and second axially adjacent rollers 3, disposed on opposite sides of the roller 3, in the direction of the longitudinal axis 2 of the chain, by a first pair of first and second links 4, 5, which are adjacent to each other in the direction of the longitudinal axis of the chain and which are pivotally mounted to the articulation element 6, for rotation relative to the articulation element 6. Each roller 3 is also respectively connected to the first and second axially adjacent rollers by a second pair of first and second adjacent links 4', 5', which are adjacent to each other in the direction of the longitudinal axis of the chain and are also pivotally mounted to the articulation element 6, for rotation relative to the articulation element 6. The first and second pairs of links 4, 4', 5, 5' are provided on an opposite sides of the longitudinal axis 2 of the chain 1. The second pair of axially adjacent links 4', 5' are laterally opposed to the first pair of links 4, 5 and corresponding links in each pair are substantially aligned in the direction of the longitudinal axis 2 of the chain 1.

The axial spacing between the adjacent rollers 3 is regular and is designed so as to receive the teeth of a drive sprocket (not shown). During use, circumferentially adjacent sprocket teeth pass on either axial side of each roller 3. Accordingly, since double articulation takes place within the confines of a single sprocket tooth gap, the chain 1 provides a double articulation chain.

Each roller 3 is tubular and has a generally thin circumferential wall that has substantially arcuate inner and outer surfaces 8, 9 (see Figure 4). Each roller 3 defines the shape of a substantially hollow cylinder centred on the roller axis 10. Each roller 3 is arranged such that its roller axis 10 is substantially parallel to a lateral axis of the chain 1, i.e. substantially perpendicular to the longitudinal axis 2 of the chain 1.

The articulation element 6 comprises a substantially solid, substantially cylindrical body having a first and second side faces 14, 15 (see Figures 3 and 6) bounded by an arcuate outer surface 7 (see Figure 4) centred on a longitudinal axis 11 of the articulation element 6.

The articulation element 6 is disposed within the roller 3 such that its longitudinal axis 11 is substantially co-axial with the roller axis 10.

The outer surface 7 of the articulation element 6 defines an arcuate bearing surface on which the inner surface 8 of the roller 3 is rotatably supported, for rotation about the roller axis 10. The outer surface 7 of the articulation element 6 is complementary to the inner surface 8 of the roller 3. The roller 3 is rotatable about the articulation element 6 by sliding its inner surface 8 against the outer surface 7 of the articulation element 6.

First and second elongate bores 12, 13 extend through the articulation element 6 from its first side face 14 to its second side face 15, along respective longitudinal axes that are substantially parallel to the longitudinal axis 11 of the articulation element 6 (see Figure 5).

The first and second bores 12, 13 are defined by respective first and second inner surfaces 29, of the articulation element 6 (see Figure 5). The first and second bores 12, 13 have a substantially circular cross sectional shape centred on the respective longitudinal axes of the bores 12, 13. The first and second bores 12, 13 are substantially diametrically opposed about the axis 11 of the articulation element 6. The longitudinal axes of the first and second bores 12, 13 are substantially aligned along the chain longitudinal axis 2.

The first and second pins 18, 19 have a substantially solid, substantially cylindrical body having an arcuate outer surface 20 (see Figure 4). The first and second pins 18, 19 are received within the first and second bores 12, 13. The outer surface 20 of each of the pins 18, 19 is complimentary to the respective first and second inner surfaces 29, 30 of the articulation element 6 that define the bores 12, 13. Each pin 18, 19 is rotatable by sliding its outer surface against the respective inner surfaces 29, 30 that define the bores 12, 13. Accordingly, the first and pins 18, 19 are rotatably supported by the articulation element 6.

The first and second inner surfaces 29, 30 of the articulation element 6, that define the first and second bores 12, 13, each substantially extend around the circumference of the outer surface 20 of the first or second pin 18, 19 respectively. Accordingly, the entire circumference of the first and second pins 18, 19 is rotatably supported by said first and second inner surfaces 29, 30 of the articulation element 6.

The first links 4, 4' of each pair of links are pivotally mounted to the articulation element 6, for rotation relative to the articulation element 6 about a first axis 16. The second links 5,5' of each pair are pivotally mounted to the articulation element 6, for rotation relative to the articulation element 6 about a second axis 17 (see Figure 3). The first and second axes 16, 17 are substantially diametrically opposed about the axis 11 of the articulation element 6.

The first and second axes 16, 17 are substantially aligned along the chain longitudinal axis 2.

Ends of each of the first links 4, 4' of each pair that are axially adjacent ends of the second links 5, 5' of each pair are provided with respective first bores 45, 45', which are co-axial with each other. The first pin 18 passes through the first bore 45 in the first link 4 of the first pair, through the first bore 12 in the articulation element 6 and into the first bore 45' of the first link 4' of the second pair of links. The first links 4, 4' of the first and second pairs are rotatably fixed to opposite ends of the first pin 18.

Ends of each of the second links 5, 5' of each pair that are axially adjacent ends of the first links 4, 4' of each pair are provided with respective second bores 46, 46', which are co-axial with each other. The second pin 19 passes through the second bore 46 in the second link of the first pair, through the second bore 13 in the articulation element 6 and into the second bore 46' of the second link 5' of the second pair of links. The second links 5, 5' of the first and second pairs are rotatably fixed to opposite ends of the second pin 19.

In this way, the axially adjacent links 4, 5, 4', 5' of each pair are rotatable relative to the articulation element 6 and therefore are rotatable relative to each other. This allows the chain 1 to articulate.

The articulation element 6 comprises an intermediary section 21 that is provided between the first and second pins 18, 19 and spaces the first and second pins 18, 19 apart such that they are not in rolling contact with each other. The intermediary section 21 of the articulation element 6 is shown by the dotted line labelled 21' in Figures 5 and 7.

The first and second inner surfaces 29, 30 of the articulation element 6, that respectively define the first and second bores 12, 13 have sections 40 (enclosed by the dotted outline labelled 40' in Figure 7) that are adjacent to each other in a direction substantially parallel to an axis 110 which passes through respective first and second longitudinal axes 111, 112 of the first and second bores 12, 13. In the current embodiment, said axis 110 is substantially perpendicular to said first and second longitudinal axes 111, 112 of the first and second bores 12, 13. Where the bores 12, 13 are diametrically opposed about the longitudinal axis 11 of the articulation element 6 (as in this embodiment) this corresponds to the radial direction of the articulation element 6.

The intermediary section 21 attaches said adjacent sections 40 of the first and second inner surfaces 29, 30 of the articulation element 6. The intermediary section 21 extends in the radial direction of the articulation element 6 from said section 40 of the first inner surface 29 to said section 40 of the second inner surface 30.

Since the first and second pins 18, 19 are rotatably supported by the articulation element 6 and the intermediary section 21 of the articulation element 6 spaces the first and second pins 18, 19 apart, the first and second pins 18, 19 are not in rolling contact with each other. This is advantageous in that the pins 18, 19 don't act to wear each other away as they rotate, during use.

In addition, the articulation element 6 is made of a filled polymer, which is a low friction material. Other suitable low friction materials include sintered materials with oil impregnation, filled polymers, composite materials, steel with PTFE coating, etc. This is a low friction material which requires no, or minimal lubrication. Therefore the chain provides a low maintenance chain that doesn't require lubrication, or only requires minimal lubrication.

Furthermore the links 4, 5, 4', 5', articulation elements 6 and pins 18, 19 of the chain 1 replace the outer links and the bushes of conventional roller bush chains. Accordingly, the arrangement provides for a relatively low cost and simple double articulation chain that uses significantly less material than a conventional roller bush chain.

In addition, since the links 4, 5, 4', 5' are pivotally mounted to the articulation element 6, the links 4, 5 can pivot relative to each other, without requiring the articulation element 6 to have two separate sections that are rotatable relative to each other, with each link 4, 5 attached to a separate section of the articulation element 6, in order to provide this. This is advantageous in that it allows the pins 18, 19 and different circumferential sections of the articulation element to be fixed to each other by the intermediary section 21 of the articulation element, which facilitates the transmission of tensile forces in the chain 1 by the articulation element 6, as opposed to by the roller 3, as described below. This prevents the roller 3 from sticking/slipping, thereby allowing efficient operation of the chain 1 under tensile loads. In addition, the intermediary section 21 also allows the articulation elements 6 to be arranged so as to increase the resistance of the chain ito twisting about the longitudinal axis 2 of the chain 1 as well as to increase the lateral stiffness of chain 1, i.e. in a direction transverse to the longitudinal axis 2 of the chain 1, also as described below. There is therefore a synergy between the pivotal mounting of the links 4, 5, 4', 5' to the articulation element and the intermediary section 21 of the articulation element 6.

The intermediary section 21 is arranged so as to prevent movement of the outer surface 7 of the articulation element 6 towards the inner surface 8 of the roller 3, when the chain 1 is under tension. Specifically, the intermediary section 21 is arranged so as to prevent movement of the outer surface 7 towards the inner surface 8 when forces on the chain 1 act to move the first and second pins 18, 19 away from each other in a direction substantially parallel to said axis 110 which passes through respective first and second longitudinal axes 111, 112 of the first and second bores 12, 13. In the current embodiment, said axis 110 is substantially perpendicular to said first and second longitudinal axes 111, 112 of the first and second bores 12, 13 (shown by the arrows in Figure 7). where the bores 12, 13 are diametrically opposed about the axis 11 of the articulation element 6 (as in this embodiment) this corresponds to the radial direction of the articulation element 6.

Specifically, the outer surface 7 of the articulation element 6, which forms the arcuate bearing surface, is a substantially continuous surface comprising first and second semi-circular sections 41, 42 disposed either side of the longitudinal axis 11 of the articulation element 6 (see Figure 7). The intermediary section 21 attaches the first and second sections 41, 42 together such that movement of the first and second sections 41, 42 towards the inner surface 8 of the roller 3 is prevented.

Accordingly, the intermediary section 21 directly attaches the inner surfaces 29, 30 of the bores 12, 13, and the first and second semi-circular sections 41, 42 of the bearing surface 7, in a direction opposite to the direction of tensile forces exerted on the chain 1. This is advantageous in that tensile forces on the chain 1, which pass from the first and second first and second pins 18, 19 into the articulation element 6, are strongly resisted by the intermediary section 21. Accordingly, the intermediary section 21 substantially prevents the tensile forces from causing the outer surface 7 of the articulation element 6 to clamp against the inner surface 8 of the roller 3. This prevents the roller 3 from sticking/slipping, thereby allowing efficient operation of the chain 1 under tensile loads. Accordingly, this allows the roller 3 to rotate even when the chain 1 is under tensile load.

In addition, since the intermediary section 21 attaches the first and second pins 18, 19 together such that movement of the pins 18, 19 towards the inner surface of the roller 3 is prevented when the chain is under tension, this ensures accurate alignment of the rollers 3 with the sprocket teeth. This means of preventing movement of the first and second pins 18, 19 under tension is stronger than simply using a bush to circumscribe the pins 18, 19, as in PCT/GB98/01873 (Renold Plc), which is discussed in the introductory section of this document.

The intermediary section 21 is integrally formed with the first and second circumferential sections 41, 42 of the outer surface 7. In addition, the intermediary section 21 is integrally formed with the remainder of the articulation element 6, i.e. to form a continuous cylindrical body. This is advantageous in that it provides a structurally strong, relative simple and cheap structure (as compared to if the intermediary section 21 was formed separately and attached to the first and second sections 41,42, e.g. by welding).

The articulation element 6 extends between laterally opposed inner surfaces of the first and second pairs of links 4, 4', 5, 5'. The side faces 14, 15 of the articulation element 6 are in close proximity to said opposed inner surfaces of the first and second pairs of links respectively. This is advantageous in that the articulation element 6 acts to resist lateral forces exerted on the chain 1, as well as twisting of the chain 1 about its longitudinal axis 2.

Each link 4, 5, 4', 5' is an elongate plate having substantially parallel upper and lower edges. Axially adjacent ends 50 of the pairs of first and second links 4, 4', 5, 5' are concavely curved so as to allow relative rotation between said ends, as the links rotate about the first and second pins 18, 19 respectively.

As stated above, Figures 3 to 7 show a longitudinal section of a double articulation chain 1 according to a first embodiment of the invention. It will be appreciated that the chain 1 comprises a plurality of these sections, each comprising said first and second pairs of links 4, 4', 5, 5' connected to a respective roller 3. It will be appreciated that the second links 5, 5' connected to a roller 3 form the first links 4, 4' of an axially adjacent roller on one axial side of the roller and the first links 4,4' connected to a roller 3 form the second links 5, 5' of an axially adjacent roller on the other axial side of the roller (and vice versa). Accordingly, each of the links 4, 5, 4', 5' are provided with said first and second bores 45, 46, 45', 46' at each axial end of the links and are rotatably mounted to articulation elements 6 of axially adjacent rollers as described above.

Referring now to Figures 8 and 9, there is a shown a longitudinal section of a chain according to a second embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the first embodiment of the invention.

The chain 1 of the second embodiment is identical to the chain 1 of the first embodiment except in that a bearing element in the form of a needle bearing 44 is provided between the outer surface 7 of the articulation element 6 and the inner surface 8 of the roller 3. Accordingly, although the outer surface 7 of the articulation element 6 rotatably supports the roller 3, it is not in direct contact with the inner surface 8 of the roller 3.

The use of the needle bearing 44 is advantageous in that it reduces friction between the inner surface 8 of the roller 3 and the outer surface 7 of the articulation element 6.

Accordingly, this prevents the roller 3 from sticking due to friction between said surfaces 8, 7.

In addition, the use of a needle bearing 44 is advantageous over the use a plain bearing, as it reduces the contact surface area between the bearing and the outer surface 7 and the inner surface 8 and so reduces frictional forces. This prevents the roller 3 from sticking on the bearing 44.

This is especially advantageous when the chain is used in a conveyor chain. In a conveyor chain, in addition to engaging with sprocket teeth, the roller is also used to carry loads and/or to guide the chain over a long span, running on a rail or other surface.

Accordingly, the rollers in conveyor chains are typically larger than in conventional chains. Due to the relatively large surface area of contact between the outer surface 7 of the articulation element 6 and the inner surface 8 of the roller 3, this increases the frictional forces between these surfaces, which can cause the roller 3 to stick. The use of the needle bearing 44 is therefore especially advantageous with a conveyor chain and allows the size of the roller to be increased.

In the current embodiment, the bearing element is a needle bearing 44. It will be appreciated that any suitable bearing elements may be used. However, for the above reasons, the bearing element is preferably a rolling element bearing (such as a needle bearing).

Referring now to Figures 10 and 11, there is a shown a longitudinal section of a chain according to a third embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the preceding embodiments of the invention.

The chain 1 of the third embodiment is identical to the chain 1 of the first embodiment except in that, for each roller, an intermediate member in the form of a steel ring 47 is provided between the outer surface 7 of the articulation element 6 and the inner surface 8 of the roller 3. Accordingly, although the outer surface 7 of the articulation element 6 rotatably supports the roller 3, it is not in direct contact with the inner surface 8 of the roller 3. This is advantageous in that the ring 47 acts to further prevent tensile forces begin transmitted from the articulation element 6 to the roller 3, thereby preventing stick/slip of roller 3 when the 1 5 chain 1 is under tension.

In addition, the first and second bores 12, 13 of the articulation element 6 open into the outer surface 7 of the articulation element 6. Accordingly, a circumferential section of each of the first and second pins 18, 19 is in rolling contact with an inner surface 150 of the steel ring 47.

In this embodiment the outer surface 7 of the articulation element 6, which forms said bearing surface, comprises first and second discrete sections 151, 152 that are spaced apart in the circumferential direction of the articulation element 6.

As with the previous embodiments, the articulation element 6 comprises an intermediary section 21 that is provided between the first and second pins 18, 19 and spaces the first and second pins 18, 19 apart such that they are not in rolling contact with each other.

The intermediary section 21 of the articulation element 6 is shown by the dotted line in Figure 10.

As with the previous embodiments, the first and second inner surfaces 29, 30, that respectively define the first and second bores 12, 13 have sections 40 that are adjacent to each other in a direction substantially parallel to an axis 110 which passes through respective first and second longitudinal axes 111, 112 of the first and second bores 12, 13. In the current embodiment, said axis 110 is substantially perpendicular to said first and second longitudinal axes 111, 112 of the first and second bores 12, 13. Where the bores 12, 13 are diametrically opposed about the axis 11 of the articulation element 6 (as in this embodiment) this corresponds to the radial direction of the articulation element 6.

The intermediary section 21 attaches said adjacent sections 40 of the first and second inner surfaces 29, 30 and said first and second sections 151, 152 of the bearing surface 7 as described for the previous embodiments, thereby providing the same advantages.

In this embodiment, the articulation element 6 is made of a polymer spacer such as glass filled nylon, or Poyether ether ketone (PEEK). This is a low friction material which requires no, or minimal lubrication. Therefore the chain is provides a low maintenance chain and doesn't require lubrication, or only requires minimal lubrication.

1 0 Referring now to Figures 12 and 13, there is a shown a longitudinal section of a chain according to a fourth embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the preceding embodiments of the invention.

The chain 1 of the fourth embodiment is identical to the chain 1 of the first embodiment except in that the first and second pins 18, 19 extend in the lateral direction from the second side face 15 of the articulation element 6. As shown in the fifth embodiment of the invention shown in Figures 14 and 15, the extended pins 18, 19 may be used to attach a second roller 50 that is laterally opposed to the first roller 3. The extended pins 18, 19 may alternatively, or additionally, be used to attach an attachment block 51 that is laterally opposed to the roller 3, as shown in the sixth embodiment of the invention shown in Figures 16 and 17. The attachment block 51 may be used to attach custom components to the chain 2 or to allow two chains running in parallel to be connected together with, for example one or more slats for conveying various materials.

The first and second pins 18, 19 may additionally, or alternatively, extend in the lateral direction from the first side face 14 of the articulation element 6, for attachment to an additional roller and/or attachment block as described above.

Referring now to Figures 18 and 19, there is a shown a longitudinal section of a chain according to a seventh embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the preceding embodiments of the invention.

The chain 1 of the seventh embodiment is identical to the chain 1 of the first embodiment except in that the articulation element 6 comprises opposed first and second side plates 61, 62, disposed on opposed lateral sides of the longitudinal axis 2 of the chain 1. Each plate 61, 62 has a generally cruciform shape having first and second ends 71, 72 that are spaced in the axial direction 2 of the chain 1 and first and second ends 73, 74, that are aligned in the axial direction 2 of the chain a. corresponding ends 71, 72, 73, 74 of the first and second plates 61, 62 are aligned in the axial direction 2 of the chain 1. Each end 71, 72, 73, 74 of the first and second plates 61,62 is rounded, to form a convex curve.

Each of the first and second plates 61, 62 are provided with first and second bores 63, 64 in the axially spaced ends 71, 72 of the plates 61, 62 and third and fourth bores 65, 66 in the axially aligned ends 73, 74 of the plates 73, 74. Each bore 63, 64, 65, 66 is defined by a respective inner surface 80 of the first and second plates 61, 62. The corresponding bores in the first and second plates are substantially co-axial.

Respective bushes 77 pass through each pair of corresponding, co-axial, bores. Each bush 77 has a generally hollow, generally cylindrical shape having an arcuate inner surface 78 and an arcuate outer surface 79. Each bush 77 is rotationally fixed within the bores that it passes through by means of a friction fit of the outer surface 79 of the bush 77 with the respective inner surface 80 of the plate 61, 62 that defines the bore. It will be appreciated that the bushes may be rotationally fixed within said bores by any other suitable means, for

example welding.

The bushes 77 that are received within the first and second bores 63, 64 of the first and second plates 61, 62 receive the first and second pins 18, 19 and rotatably support said pins 18, 19. Each of these bushes 77 has an inner surface 78 that is complementary to the outer surfaces 20 of the pins and rotatably supports the pins 18, 19. Accordingly, these bushes 77 replace the first and second bores 12, 13 of the previous embodiments. The bushes 77 that are received within the third and fourth bores 65, 66 do not receive any pins and are redundant. However, they allow each of the first and second plates 61, 62 to be formed from substantially the same components. In addition, this arrangement allows the first and second plates to be made from conventional, readily available chain link plates.

Inner rollers 89 are rotatably mounted on the outer surface 79 of each bush 77 respectively. A circumferential section of an outer surface 95 of each inner roller 89 is in contact with the inner surface 8 of the roller 3. Accordingly, in this embodiment, said circumferential sections of the outer surfaces 95 of the inner rollers 89 form the bearing surface of the articulation element 6.

Alternatively, the bushes 77 may be provided without the inner rollers 89 and be arranged such that a circumferential section of the outer surface 79 of each bush 77 is in contact with the inner surface 8 of the roller 3. Accordingly, in this embodiment, said circumferential sections of the outer surfaces 79 of the bushes 77 form the bearing surface of the articulation element 6.

In this embodiment, the intermediary section 21 of the articulation element 6 is formed by respective sections of the first and second plates 61, 62 that are provided between the first and second pins 18, 19 and spaces the first and second pins 18, 19 apart such that they are not in rolling contact with each other. The intermediary section 21 of the articulation element 6 is shown by the dotted line labelled 21' in Figure 18.

The respective inner surfaces 80 that respectively define the first and second bores 63, 64 have sections 90 that are adjacent to each other in a direction substantially parallel to an axis 110 which passes through respective first and second longitudinal axes 111, 112 of the first and second bores 63, 64. In the current embodiment, said axis 110 is substantially perpendicular to said first and second longitudinal axes 111, 112 of the first and second bores 63, 64.

Where the bores 63, 64 are diametrically opposed about the axis 11 of the articulation element 6 (as in this embodiment) this corresponds to the radial direction of the articulation element 6.

The intermediary section 21 attaches said adjacent sections 90 of the first and second inner surfaces 80 and said circumferential sections of the outer surfaces 79 of the bushes 77 that are received within the first and second bores 63, 64 to provide the same advantages as described in the preceding embodiments.

Accordingly, in this embodiment, the articulation element 6 comprises said circumferential sections of the bushes 77, which form the bearing surface and said sections of the first and second plates 61, 62 which form the intermediary section 21.

Each said circumferential section the outer surface 95 of each inner roller 89 (or of the bush, where there are no inner rollers) has a radius of curvature that is substantially less than the radius of curvature of the inner surface 8 of the roller 3. This is advantageous in that it reduces the contact surface area between the bearing surface of the articulation element (formed by said outer surfaces 95 of each inner roller 89) and the inner surface 8 of roller 3 (as compared to if the bearing surface was a continuous surface in contact with the inner surface of the roller 3). This reduces friction between said surfaces, thereby providing a more efficient chain 1 and preventing the rollers 3 from sticking.

In addition, because the bearing surface comprises a plurality of circumferentially spaced surfaces, the bearing surface still supports roller 3 across its inner circumference so as to prevent it from flattening.

Furthermore, since the articulation element 6 is formed by the first and second plates 61, 62 and said circumferential sections of the bushes 77, the articulation element may be formed from conventional, readily available, chain links, bushes and/or rollers, thereby lowering cost of manufacture.

Referring now to Figures 20 and 21, there is shown a longitudinal section of a chain according to an eighth embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the preceding embodiments of the invention. The chain of the embodiment is identical to the chain 1 of the first embodiment except in the first and second links 4, 5 (and 4', 5') of each pair partially overlap each other in the direction of the longitudinal axis 2 of the chain 1.

Specifically, the first pin 18 extends in the lateral direction from the first and second side faces 14, 15 of the articulation element 6, the first link 4, 4' of each pair is provided laterally outwardly of the second link 5, 5' of each pair and overlaps the second linkS, 5' in the direction of the longitudinal axis 2 of the chain 1.

In addition, a spacer 115 may be provided between the side faces 14, 15 of the articulation element 6 and the link plates 4, 4' so as to ensure that the links 4, 4' are laterally aligned during articulation as shown in Figure 22.

It will be appreciated that, alternatively, the second link 5, 5' of each pair may provided laterally outwardly of the first link 4, 4' of each pair and overlap the first link 4, 4' in the direction of the longitudinal axis 2 of the chain 1.

In view of the above, it can be seen that the chain according to the invention provides a double articulation roller chain that has low wear during use, is able to bear a tensile load, without preventing the rollers of the chain from rotating, is resistant to twisting and has relatively high lateral stiffness, doesn't require lubrication, or only requires minimal lubrication, is relatively inexpensive and has a flexible configuration.

Referring to Figure 23, there is shown a ninth embodiment of the invention. For convenience and ease of understanding the same reference numbers are used for parts in common with the preceding embodiments of the invention. The chain of the embodiment is identical to the chain 1 of the seventh embodiment except in that the upper end 73 of the first and second plates 61, 62 and the roller 3 has been removed. In addition the roller 703 that is mounted on the bush 77 of the lower end 74 of the first and second plates 61, 62 has been enlarged. During use, sprocket teeth of a sprocket wheel (not shown) trace a path 303 and engage the outer surfaces 95 of the inner rollers 89 of the first and second ends 71, 72 of the plates 61, 62 and an outer surface of the enlarged roller 703. specifically, first and second circumferentially adjacent sprocket teeth respectively pass either side of the enlarged roller 703, engaging the enlarged roller 703 and the inner roller 89 on that respective side of the enlarged roller 703.

In addition, the enlarged roller 703 is arranged to roll on a conveyor guide.

This is advantageous in that the first and second rollers can be arranged to engage sprocket teeth that pass either side of the rollers, so as to lower wear on the first and second pivot members, while the third roller is able to roll on a conveyor guide.

Since the contacting surface areas of inner surfaces of the rollers 89, 703 with outer surfaces of the bushes 77 is relatively small, this decreases the frictional forces between these surfaces and therefore prevents the rollers 89, 703 from sticking.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected.

For example, in the above described embodiments of the invention, each roller 3 is respectively connected to first and second axially adjacent rollers 3, disposed on opposite sides of the roller 3, in the direction of the chain longitudinal axis 2, by a first pair of first and second axially adjacent links 4, 5, which are pivotally mounted to the articulation elements 6 and by a second pair of first and second axially adjacent links 4', 5' which are also pivotally mounted to the articulation elements 6, and are provided on an opposite side of the longitudinal axis 2 of the chain 1. The second pair of axially adjacent links 4', 5' are laterally opposed to the first pair of links 4, Sand corresponding links in each pair are substantially aligned in the direction of the longitudinal axis 2 of the chain 1. Accordingly, each roller is connected to four links 4,4', 5, 5'.

Alternatively, each roller may be connected to first and second axially adjacent rollers 3, disposed on opposite sides of the roller 3, in the direction of the chain longitudinal axis 2,, only by the first pair of first and second axially adjacent links 4, 5 (or 4', 5'). Each of the first pair of axially adjacent links 4, 5 may be provided on the same lateral side of the chain.

Alternatively, each of the first pair of axially adjacent links 4, 5 may be provided on opposite lateral sides of the chain, i.e. opposite sides of the longitudinal axis 2 of the chain 1.

Axially adjacent rollers 3 may have any of the above arrangements of links 4, 5, 4', 5'.

Accordingly, chains with a large number of different arrangements of links fall within the scope of the present invention.

It should be understood that while the use of words such as "preferable", "preferably", "preferred" or "more preferred" in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be contemplated as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

CLAIMS1. A chain defining a longitudinal axis along its length, the chain comprising a plurality of tubular rollers spaced in the direction of the longitudinal axis of the chain, each roller being connected to first and second axially adjacent rollers, disposed either side of the roller, by first and second links respectively, wherein an articulation element is received within each roller that defines an arcuate bearing surface on which an inner surface of the roller is rotatably supported and the first and second links are pivotally mounted to the articulation element, for rotation relative to the articulation element about first and second spaced axes, by first and second pivot members respectively which are rotatably supported by the articulation element and wherein the articulation element comprises an intermediary section provided between the first and second pivot members that spaces the first and second pivot members apart such that they are not in rolling contact with each other.
2. A chain according to claim 1 wherein the first and second pivot members are received within first and second bores in the articulation element, defined by respective first and second inner surfaces of the articulation element and respective outer surfaces of the first and second pivot members are rotatably supported by said first and second inner surfaces of the articulation element.
3. A chain according to claim 2 wherein the first inner surface of the articulation element substantially extends around the circumference of the outer surface of first pivot member and/or the second inner surface of the articulation element substantially extends around the circumference of the outer surface of second pivot member.
4. A chain according to either of claims 2 or 3 wherein the first inner surface of the articulation element and/or the second inner surface of the articulation element is formed from a low friction material.
5. A chain according to any preceding claim wherein the intermediary section is arranged so as to constrain movement of the arcuate bearing surface towards the inner surface of the roller when the chain is put under tension.
6. A chain according to claim 5 wherein the intermediary section is arranged so as to constrain movement of the arcuate bearing surface towards the inner surface of the roller when forces on the chain act to move the first and second pivot members away from each other.
7. A chain according to either of claims 5 or 6 wherein the arcuate bearing surface comprises first and second sections located at different circumferential positions relative to the inner surface of the roller and the intermediary section of the articulation element attaches the first and second sections together such that movement of the first and second sections towards the inner surface of the roller is constrained.
8. A chain according to claim 7 when dependent on claim 2 wherein the intermediary section extends from the first section to the second section in a direction substantially parallel to an axis which passes through respective first and second longitudinal axes of the first and second bores.
9. A chain according to either of claims 7 or 8 wherein the intermediary section is integrally formed with the first and second circumferential sections of the bearing surface.
10. A chain according to any preceding claim wherein the intermediary section attaches the first and second pivot members together such that movement of the first and second pivot members towards the inner surface of the roller is constrained.
11. A chain according to claim 10 when dependent on claim 2 wherein the intermediary section attaches the first and second inner surfaces of the articulation element that define the first and second bores.
12. A chain according to claim 11 wherein the intermediary section attaches sections of the first and second inner surfaces that are adjacent to each other.
13. A chain according to any preceding claim wherein the bearing surface of the articulation element is complementary to the inner surface of the roller.
14. A chain according to any preceding claim wherein the bearing surface of the articulation element is a continuous surface.
15. A chain according to any of claims 1 to 13 wherein the bearing surface comprises a plurality of discrete sections, spaced apart in the circumferential direction of the inner surface of the roller.
16. A chain according to claim 15 wherein each section of the bearing surface has a radius of curvature that is substantially less than the radius of curvature of the inner surface of the roller.
17. A chain according to any preceding claim wherein the articulation element comprises a first pivot member support, which has an inner surface that is complementary to an outer surface of the first pivot member and rotatably supports the first pivot member and an outer surface of the first pivot member support forms the, or a section of, the bearing surface of the articulation element, or a bearing element is rotatably supported on the outer surface of the first pivot member support and an outer surface of the bearing element forms the, or a section of, the bearing surface of the articulation element.
18. A chain according to claim 17 wherein the articulation element comprises first and second side plates, disposed on opposed lateral sides of the longitudinal axis of the chain, each provided with a first bore defined by a respective inner surface of the respective plate and the first pivot support member passes through said bores and is supported by said inner surfaces.
19. A chain according to either of claims 17 or 18 wherein the articulation element comprises a second said pivot member support spaced from the first pivot member support in the circumferential direction of the inner surface of the roller.
20. A chain according to any of claims 17 to 19 wherein the articulation element comprises a third said pivot member support disposed, in the circumferential direction of the inner surface of the roller between the first and second pivot member supports.
21. A chain according to claim 20 wherein the third pivot member does not house a pivot member.
22. A chain according to 19, wherein the first and second pivot member supports form a first pair of pivot member supports and the articulation element comprises a second said pair of first and second pivot member supports, wherein in the first pair the first pivot member support is diametrically opposed to the second pivot member support about a first axis and in the second pair the first pivot member support is diametrically opposed to the second pivot member support about a second axis and said first and second axes are substantially perpendicular to each other.
23. A chain according to any preceding claim wherein an intermediate member is provided between the bearing surface of the articulation element and the inner surface of the roller.
24. A chain according to claim 23 wherein the intermediate member is a bearing element
25. A chain according to claim 24 wherein the bearing element is a needle bearing.
26. A chain according to any of claims 23 to 25 wherein the intermediate member is a ring.
27. A chain according to any preceding claim wherein the first and second links are provided on the same lateral side of the chain.
28. A chain according to any of claims 1 to 26 wherein the first and second links are provided on opposite lateral sides of the chain.
29. A chain according to claim 28 wherein the articulation element extends between laterally opposed surfaces of the first and second links and supports the first and second links in the lateral direction.
30. A chain according to any preceding claim wherein each roller is connected to the first and/or second axially adjacent rollers by a second said first and/or second link respectively, that is laterally opposed to the first and/or second link respectively and is also rotatably mounted to the articulation element by the first and/or second pivot member respectively.
31. A chain according to any preceding claim wherein the first and/or second pivot member extends in the lateral direction from at least one side face of the articulation element for attachment to a roller or attachment block.
32. A chain according to any preceding claim wherein axially adjacent ends of the first and second links are curved so as to allow relative rotation between said ends, as the links rotate about the first and second pivot members respectively.
33. A chain substantially as described herein, with reference to the accompanying drawings.