WO1999000610A1

WO1999000610A1 - A chain

Info

Publication number: WO1999000610A1
Application number: PCT/GB1998/001873
Authority: WO
Inventors: Michael Charles Christmas
Original assignee: Renold Plc
Priority date: 1997-06-28
Filing date: 1998-06-25
Publication date: 1999-01-07
Also published as: GB9713632D0; AU8224398A

Abstract

A chain comprises a plurality of spaced bushes (3) that are interconnected by rigid elongate link members (2). The link members have end portions (5) that are each rotatably received in one of said plurality of bushes. Adjacent end portions in a given bush are interconnected such that the link members are rotatable relative to each other. The interconnection of the link members can be achieved in several different ways.

Description

A CHAIN

The present invention relates to a chain of the kind that is used, generally in combination with a sprocket, in drive or lifting mechanisms etc..

A conventional roller chain that is generally used in such applications comprises pairs of opposed inner link plates interspersed along the length of the chain by pairs of opposed outer link plates. Each outer link overlies the adjacent ends of neighbouring inner links such that an aperture at each end of the outer link is aligned with an corresponding aperture in the end of the underlying inner link plate. The inner and outer link plates are interconnected on opposite sides of the chain by means of a pin that passes through the aligned apertures on each side. The pin is fixed at each end to the opposed outer link plate but is pivotal relative to the inner link plates within a bush that extends between opposed apertures in the inner link plates. Such chains are relatively costly to produce and relatively complex in their assembly.

It is an object of the present invention to provide for a chain that is relatively inexpensive to manufacture and assemble.

According to the present invention there is provided a chain comprising a plurality of spaced bushes that are interconnected by rigid elongate link members having end portions that are each rotatably received in one of said plurality of bushes, adjacent end portions in a given bush being interconnected such that the link members are rotatable relative to each other.

The adjacent end portions may be interconnected by means of a threaded connecting member. In a preferred embodiment the end portions have threaded bores that each engage with a common threaded stud.

Alternatively the end portions may have inter-engaging formations that permit relative rotation of the link members. In a preferred embodiment each formation has a projection that is received in a recess in the other formation. The projection and recess are preferably arcuate.

In an alternative embodiment the end portions are retained in the bush by means of a housing member having retaining elements that prevent the end portions from moving out of the bush. The housing member may be received inside or outside the bush and the retaining elements may be walls that project in a direction substantially parallel to the longitudinal axis of the chain. The housing may be filled with lubricating matter such as grease or the like.

In a further preferred alternative embodiment the end portions overlie each other within the bush and may each have convex surfaces that are in rolling contact with one another so as to permit relative movement of the link members. Each end portion may have a terminal tongue that extends radially of the bush and engages therewith to prevent removal of the link member from the bush. Preferably the tongue abuts a side face of the bush which may be provided with a radial slot to permit entry of the end portion. The bush is rotatable relative to the end portions of the link members to a locking position in which locking elements on the bush and a first of the end portions engage to prevent relative movement of said first end portion and said bush. The locking elements are preferably a rib and a complementary groove. The rib may be defined on an interior surface of bush and the groove defined in said first end portion.

In a still further preferred embodiment the end portions are interconnected by an intermediate insert in the bush. The insert is fixed relative to the bush and at least one end portion is able to move rotationally relative thereto. The end portion rotatably engages the insert so as to prevent lateral movement thereto.

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 is a sectioned plan view of part of a length of chain in accordance with the present invention;

Figure la is a sectioned plan view of the chain of figure 1 with link plates;

Figure 2 is a scrap view of a part of the chain of figure 1 showing an arrangement for interconnecting link members;

Figures 3 to 6 are sectioned scrap views of alternative interconnection arrangements; Figure 7 is an enlarged view of part of figure 6;

Figure 8 is a sectioned view along line X-X of figure 6 showing the disposition of a bush of the invention during insertion of the link members;

Figure 9 is a view of the bush of figure 8 after insertion and locking;

Figure 10 is a sectioned plan view of part of a length of chain with a further alternative interconnection arrangement;

Figure 11 is an enlarged view of a single link of the chain of figure 10; and

Figure 12 is a sectioned view along line AA of figure 11.

Referring now to the drawings, figure 1 shows part of a length of chain comprising a plurality of spaced bush roller assemblies 1 interconnected by wire links 2. The spacing between adjacent bush roller assemblies 1 is designed so as to receive the teeth of a drive sprocket (not shown).

Each bush roller assembly 1 comprises a cylindrical bush 3 on which is coaxially mounted a rotary roller 4. Each bush roller assembly 1 is connected to the two neighbouring bush roller assemblies 1 by the wire links 2, adjacent bush pairs 3 being interconnected by a single wire link 2. On one side of the chain alternate bush pairs 3 are interconnected by C-shaped wire links and on the other side intermediate bush pairs are interconnected by reverse C-shaped wire links. Each bush 3 receives a free end portion 5 of each link type in coaxial alignment such that the links 2 are free to pivot relative to the bush 3 and to each other. The links 2 are interconnected at abutting end portions 5 by means described below.

Figure la shows the chain of figure 1 supplemented with plate links 6 that underlie the wire links 2 and provide improved guidance of the chain around the sprocket. The plate links 6 may be manufactured from, for example, a polymer.

Figure 2 shows one method of interconnecting the abutting end portions 5 of the wire links 2. A threaded stud 7 is received in threaded blind bores 8 in each of the abutting end faces of the wire links 2. There is a small clearance 9 between the end portions 5 so that a central portion of the thread on the stud 7 is not engaged by the links 2 thereby providing scope for rotation of the links 2 on the stud 7. In an alternative embodiment shown in figure 3 the end portions 5 of the links inter-engage by means of an arcuate tongue 10 and groove 11 connection that effectively forms a threaded engagement of half a turn.

Figures 4 and 5 show further alternative embodiments in which the bush 3 or roller 4 are modified in such a way so as to retain the wire links 2. In figure 4 the bush 3a comprises a two part housing of, for example, plastics. Each part of the housing comprises a half cylinder 12 with a terminal circular wall 13 and is a snap-fit with the other part. The half cylinder 12 extends laterally outwardly of the roller 4 to beyond the lateral extremity of the wire link 2 and the terminal circular wall 13 extends substantially parallel to and towards the link so as to prevent it from moving out of the bush 3 a. In figure 5 the bush 3 is of conventional design and instead the roller 4a is in the form of a two part housing as described above. In both designs the wire links 2 are free to rotate relative to the bush 3 and to each other. Whilst the end portions 5 of the links 2 are retained in the bush 3, 3a by the terminal circular wall 13 of the bush 3, 3a or roller 4, 4a they may also be interconnected in the manner described above in relation to figures 2 and 3. The housing forms an enclosure with the wire links 2, the enclosure being sealed sufficiently to store lubricating grease or the like.

Referring now to figures 6 to 9 there is shown an alternative method of interconnecting the wire links 2 in the bushes 3. The end portions 5 of the wire links 2 are longer than those described above in relation to figures 1 to 5, each being approximately as long as the bush 3 but of reduced thickness so that they overlie each other in the bush 3. The overlying portions are approximately oval in cross section (see figure 8), each having a radially inward facing convex surface 20 and an radially outward facing convex surface 21 which are approximately of the same radius of curvature. The overlying end portions 5 are in rolling contact along the inward facing convex surfaces 20 so as to permit relative rotation of the wire links 2.

The end portions 5 of the wire links 2 project beyond the bush 3 and terminate in a tongue 22 (see figure 7) that extends radially outwardly thereby preventing significant lateral movement of the links 2 within the bush 3. A complementary, rectangular, radially outward extending slot 23 is provided in the bush 3 and is designed to receive a tongue 22 of one of the end portions 5. In addition, an arcuate shallow rib 24 is provided in the bush 3 at a angular displacement of 90° thereto. The rib is designed to engage with a corresponding groove 25 in an outwardly facing surface 21 of one of the end portions 5. In order to assemble the chain an end portion 5 of a first wire link 2 is inserted into the bush 3 until the tongue 22 projects from the other end. The second wire link end portion 5 is then offered to the bush 3 with its tongue 22 aligned with the rectangular slot 23. The tongue 22 is received by the slot 23 and is slid along the length of the bush 3 until it projects from the opposite end. It will be seen from figure 8 that in this configuration the rib 24 projects into space between the two end portions 5 thereby not interfering with the passage of the end portion 5. When both end portions 5 are in place the bush 3 is rotated relative to them through 90 until the rib 24 engages in the groove 25 thereby preventing further rotation of the bush 3 and locking it in place so that the tongue 22 cannot be prevented from moving towards engagement with the slot 23 to enable release of the wire links 2. In use the rolling contact of the end portions 5 minimises wear.

In a further embodiment of the present invention shown in figures 10 to 12 the chain comprises a plurality of inner link assemblies 30 that are interconnected on each side by wire outer links 31. Each inner link assembly 30 comprises a pair of opposed inner link plates 32 each having two spaced bushes 33 that are received in apertures 34 in the inner link plates 32 as in a conventional bush roller chain. The bushes 33 each support a coaxial roller 35. End portions 36 of the wire outer links 31 are received in a bush 33 but are interconnected by an intermediate insert 37 that is seated in the bush 33. The insert 37 which may be manufactured from, for example, a polymer or metal is approximately of inverted T-shape in cross-section with a central stem 38 closing the aperture in the bush 33 and two arms 39 that are formed to engage the outer links. Each arm 39 is of oval cross-section with an upper convex surface 40 (see figure 12) that is designed to underlie a corresponding convex surface 41 of the end portion 36 of the link 31 as can be seen from figure 12. A terminal portion of the link 31 has a projecting element 42 that is received in a corresponding recess 43 in the insert 37 so as to permit relative rotation but prevent movement of the link 31 out of the bush 33. The insert 37 is manufactured from two parts which are connected together by a snap-fit connection during assembly within the bush 33. The insert may be keyed to the interior of the bush 33 to prevent rotation. In operation the convex surface 41 of the link 31 is in rolling contact with the convex surface 40 of the insert 39 so as to permit relative movement whilst reducing wear.

It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the bush and roller may be replaced by a single component to reduce the number of parts and therefore the cost.

Claims

1. A chain comprising a plurality of spaced bushes that are interconnected by rigid elongate link members having end portions that are each rotatably received in one of said plurality of bushes, adjacent end portions in a given bush being interconnected such that the link members are rotatable relative to each other.

2. A chain according to claim 1, wherein the adjacent end portions are interconnected by means of a threaded connecting member.

3. A chain according to claim 2, wherein the end portions have threaded bores that each engage with a common threaded stud.

4. A chain according to claim 1, wherein the end portions have inter-engaging formations that permit relative rotation of the link members.

5. A chain according to claim 4, wherein each formation has a projection that is received in a recess in the other formation.

6. A chain according to claim 5, wherein the projection and recess are arcuate.

7. A chain according to claim 1, wherein the end portions are retained in the bush by means of retaining elements that prevent the end portions from moving out of the bush.

8. A chain according to claim 7, wherein the bush is in the form of an enclosure having retaining elements that project in a direction substantially parallel to the longitudinal axis of the chain.

9. A chain according to claim 7, wherein there is a roller mounted on the bush, the roller being in the form of an enclosure and having the retaining elements.

10. A chain according to claim 8 or 9, wherein the enclosure is filled with lubricating matter such as grease or the like.

11. A chain according to claim 1, wherein the end portions overlie each other within the bush.

12. A chain according to claim 11, wherein the end portions have convex surfaces that are in rolling contact with one another so as to permit relative movement of the link members.

13. A chain according to claim 11 or 12, wherein each end portion has a terminal tongue that extends radially of the bush and engages therewith to prevent removal of the link member from the bush.

14. A chain according to claim 13, wherein the tongue abuts a side face of the bush which is provided with a radial slot to permit entry of the end portion.

15. A chain according to any one of claims 11 to 14 , wherein the bush is rotatable relative to the end portions of the link members to a locking position in which locking elements on the bush and a first of the end portions engage to prevent relative movement of said first end portion and said bush.

16. A chain according to claim 15, wherein the locking elements are a rib and a complementary groove.

17. A chain according to claim 16, wherein the rib is defined on an interior surface of the bush and the groove defined in said first end portion.

18. A chain according to claim 1, wherein the end portions are interconnected by an intermediate insert in the bush.

19. A chain according to claim 18, wherein the insert is fixed relative to the bush and at least one end portion is able to move rotationally relative thereto.

20. A chain according to claim 19, wherein the end portion rotatably engages the insert so as to prevent lateral movement thereto.

21. A chain substantially as hereinbefore described with reference to figures 1, 1a, 2, 3, 4, 5, 6 to 9 and 10 to 12 of the accompanying drawings.