A CHAIN

Abstract: A drive chain comprises a plurality of inner links (1) interconnected by intermediate outer links and elongate pins (7) that are received in apertures in the inner and outer links. There is substantial clearance between the outer link and the corresponding inner links so as to permit flexion of the adjacent elongate pins in a direction substantially parallel to the length of the chain. The outer link may be in the form of a separate plate (6) or may be an integral part of the pins. In one embodiment the outer link is a crimped plate that offers resilience in the direction of the chain. The drive chains provide for shock absorption.

Description: A CHAΪN The present invention relates to a chain and more particularly, but not exclusively, to a drive chain or lifting chain of the kind having a plurality of inner links connected by intermediate outer links. Conventional roller chains comprise a sequence of inner links interconnected by intermediate outer links and pins which are received in said inner links and are secured by interference fit in holes provided in the outer links. Each pin is located in a fixed bush which supports a rotatable cylindrical roller and which extends between opposed inner link plates. In some harsh applications shock loads to a drive or lifting arrangement are carried by the chain resulting in chain failure through fatigue. It is an object of the present invention to obviate or mitigate the aforesaid disadvantage by providing for a shock absorbing drive or lifting chain and/or a low cost chain. According to a first aspect of the present invention there is provided a chain comprising a plurality of inner links each having at least one elongate pin, adjacent elongate pins of neighbouring inner links being connected together by an outer link portions, wherein there is sufficient spacing between an outer link portion and the corresponding inner links so as to permit flexing of the adjacent elongate pins in a direction substantially parallel to the length of the chain. It is the capacity of the elongate pins to flex that advantageously provides the chain with a shock absorption capability when it is subject to harsh or sudden loads. An outer link portion may be provided at each end of the adjacent elongate pins so as to form a closed loop. The or each outer link portion, for example, may integral with each of the adjacent elongate pins. Alternatively, the or each outer link portion may be a separate link plate secured to ends of adjacent elongate pins, in which case the or each outer link plate is preferably secured to the elongate pin ends by means of an interference fit. The elongate pins may each be fitted with a collar so that their lateral movement relative to the inner links is prevented. Such a collar is preferably an interference fit on the pin, however, it may take the form of a spacer extending along the length of the elongate pin between the inner link and the outer link portion. Preferably the outer link portion is resiliency flexible in a direction parallel to the chain length. Each outer link portion may be in the form of a crimped plate, a crimped portion of which is resiliency extensible. A plurality of such outer link portions may be connected between adjacent elongate pins. According to a second aspect of the invention there is provided a drive chain comprising a plurality of inner links each having at least one pin that is received in apertures in the inner links, adjacent pins of neighbouring inner links being connected together by an outer link portion, wherein the outer link portion is resiliency flexible in a direction along the length of the chain. The outer link portion may, for example, be an oval shaped plate having an aperture, a U-shaped plate with adjacent pins being received in apertures in each limb of the U-shape or an S -shaped plate. The S-shaped plate is preferably formed from spaced slots extending from opposed edges of the plate, the slots extending in a direction perpendicular to the length of the chain. The oval shaped plate may a single central aperture or alternatively a plurality of apertures that may be in the form of diamond shaped cut-outs. According to a third aspect of the present invention there is provided a drive chain comprising a plurality of inner links interconnected by a connection link having parallel limbs that pass through apertures in the inner links and at least one integral portion interconnecting the limbs. The connection link may be open at one end to define a U-shape or, alternatively may be closed at both ends to define a closed loop. 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 plan view of part of a first embodiment of a drive chain according to the present invention; Figure 2 is a plan view of part of a second embodiment of a drive chain according to the present invention; Figure 3 is a plan view of part of a third embodiment of a drive chain according to the present invention; Figure 4 is a plan view of part of a fourth embodiment of a drive chain according to the present invention; Figure 5 shows plan and side views of part of a fifth embodiment of a drive chain according to the present invention; Figure 6 shows plan and side views of part of a sixth embodiment of a drive chain according to the present invention; Figure 7 shows plan and side views of part of a seventh embodiment of a drive chain according to the present invention; Figure 8 shows plan and side views of part of a eighth embodiment of a drive chain according to the present invention; Figure 9 is a plan view of part of a ninth embodiment of a drive chain according to the present invention; and Figure 10 is a plan view of part of a tenth embodiment of a drive chain according to the present invention. Referring now to the drawings, figure 1 shows part of a roller and bush chain comprising a plurality of inner links 1 that are of conventional design. Each inner link 1 comprises a pair of opposed inner link plates 2 each of which has a pair of apertures 3 and is connected to the opposed plate by two bushes 4 (shown in dotted line) whose ends engage in the apertures 3. Each bush 4 supports a rotary cylindrical roller 5 between the inner link plates. Adjacent inner links 1 are interconnected by flanking outer link plates 6 that are mounted on elongate pins 7 passing through the bushes 5 and the inner link plates 2. Each elongate pin 7 is rotatably received in the bush 5 and extends well beyond the inner link plates 2 on each side. The end of each elongate pin 7 is connected to an adjacent elongate pin 7 of the neighbouring inner link 1 by means of the outer link plate 6 which is secured on the ends of the said adjacent elongate pins 7 by means of an interference fit between the elongate pin 7 and apertures 8 provided in the outer link plate 6. It will be understood that, as in a conventional roller chain, the inner links 1 are pivotal relative to the outer link plates 6 and the elongate pins 7 on which they are mounted. In order to prevent lateral movement of the pins 7 relative to the inner links 1 , washers 9 are mounted with interference fit on the pins 7, each washer 9 abutting an outwardly facing surface of the inner link plate 2. It will be seen from figure 1 that there is a significant lateral clearance between the inner and outer link plates 1,2 by virtue of the extended length of the pins 7 compared to that of a conventional roller chain. This design permits the elongate pins 7 to flex in a direction parallel to the chain length when the chain is under load, thereby providing shock absorption. The length and flexibility of the pins 7 can be selected according to the application. Variations of the chain design of figure 1 are shown in figures 2 to 4. Components common to the two designs are given the same reference numeral and are not described except insofar as they differ from their counterparts. In figure 2 adjacent inner links 1 of the shock absorbing drive lifting chain are interconnected by a U-shaped pin 10 , the limbs 11 of the U-shape corresponding to the pins of the design in figure 1 and the base 12 of the U-shape replacing one of the outer link plates. The U-shaped pin 10 is closed by an outer link plate 6 connected to the two ends 12 of the pin 10 in the same way as that described in relation to the design of figure 1. In figure 3 the adjacent inner links 1 are interconnected by a single pin 13 that is bent into an enclosed ring shape. Ends 14 of the pin 13 are joined by means of, for example, a weld 15 . In the embodiment shown in figure 4 each outer link plate of the design shown in figure 1 is replaced by a plurality of parallel crimped plates 16 spaced along the protruding ends of the elongate pins 6. Each crimped plate 16 is made, for example, of spring steel and permits elastic extension of the plates under load thereby giving the chain resilience in the longitudinal direction. The number of crimped plates 16 can be selected according to the application. In the simplest design a single crimped plate 16 is connected to each end of adjacent pins of conventional length i.e. the crimped plate replaces an outer link plate of a conventional roller and bush chain. The plates could be manufactured from other resilient elastic material such as a polymer. Figures 5 to 8 show different embodiments of a shock absorbing chain in which the outer link plates are designed to deflect under load. The shape of the outer link plates is designed such that under load the plates are subject not only to a tensile load (as in the outer link of a conventional link) but also to a bending moment. Each of the outer link plates is connected with interference fit to pins of a conventional length such that there is no or little clearance between adjacent inner and outer link plates. The outer link plate 17 of figure 5 is, in side view, of general oval configuration with a central oval aperture 18. In figure 6 the outer link plate 19 is U-shaped being formed from approximately half of the outer link plate of figure 5. Ends of the limbs 20 of the U-shaped plate are connected to pins 21 of conventional length by means of an interference fit. It is to be understood that outer link plates of this configuration could be used in the designs of figures 1 and 2 in which elongate pins are used. In figure 7 the outer link plate 22 is again of generally oval configuration but has two parallel spaced slots 23 that extend in a direction substantially perpendicular to the longitudinal length of the chain (as indicated by the arrow). The slots 23 commence at opposite edges of the outer link plate 22 and terminate at a distance short of the opposing edge thereby forming an S-shaped outer link plate 22. The outer link plate 24 of figure 8 is of oval shape with a plurality of diamond-shaped apertures or cut-outs 25. In figure 9 there is shown a lifting chain in which the inner links 1 are interconnected by a pin 26 that is bent to form a closed ring in the same manner as the embodiment shown in figure 3. The pin 26 is smaller than that shown in figure 3 and therefore does not offer the same shock absorption facility. However, this pin design may be used as shown instead of the outer link plates of a conventional drive chain. A variation of the design of figure 9 is shown in figure 10. Here adjacent inner links 1 are interconnected by U-shaped pins 27 arranged along the chain such that they alternately face in opposite directions. Free ends 28 of the pins engage with apertures 3 in the inner link plates 2 in an interference fit. This arrangement permits the chain to flex both along its length and laterally thereto thereby providing shock absorption under load. 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 interference fit washers shown in the embodiments of figures 1 to 4 may be replaced by spacers that extend along the length of the pin between the inner link plate and the outer link plate or its equivalent. Moreover, it will be understood that the embodiments shown in figures 5 to 8 are shown as examples only of a chain with a resiliently flexible outer link and that there are many other equivalent designs that are contemplated.

Claims: CLAIMS 1. A chain comprising a plurality of inner links each having at least one elongate pin, adjacent elongate pins of neighbouring inner links being connected together an outer link portion, wherein there is sufficient spacing between an outer link portion and the corresponding inner links so as to permit flexing of the adjacent elongate pins in a direction substantially parallel to the length of the chain. 2. A chain according to claim 1, wherein the outer link portion is integral with said adjacent elongate pins. 3. A chain according to claim 1, wherein the link portion is a separate link plate secured to ends of adjacent elongate pins. 4. A chain according to claim 3, wherein the outer link plate is secured to the elongate pin ends by means of an interference fit. 5. A chain according to claim 2,3 or 4, wherein the outer link portion is connected at both ends of the adjacent elongate pins, thereby forming a closed loop. 6. A chain according to any preceding claim, wherein the elongate pins are each fitted with a collar so that their lateral movement relative to the inner links is prevented. 7. A chain according to claim 6, wherein the collar is an interference fit on the elongate pin. 8. A chain according to claim 6, wherein the collar is in the form of a spacer extending along the length of the elongate pin between the inner link and the outer link portion. 9. A chain according to any preceding claim, wherein the outer link portion is resiliently flexible in a direction parallel to the chain length. 10. A chain according to claim 9, wherein the outer link portion is a crimped plate, a crimped portion of which is resiliently extensible. 11. A chain according to claim 9 or 10, wherein a plurality of outer link portions are connected between adjacent elongate pins. 12. A chain comprising a plurality of inner links each having at least one pin that is received in an aperture in the inner link, adjacent pins of neighbouring inner links being connected together by an outer link portion, wherein the outer link portion is resiliently flexible in a direction along the length of the chain. 13. A chain according to claim 12, wherein the outer link portion is a crimped plate, a crimped portion of which is resiliently extensible. 14. A chain according to claim 13, wherein the outer link portion is an oval shaped plate having an aperture. 15. A chain according to claim 13, wherein the outer link portion is a U-shaped plate with adjacent pins being received in apertures in each limb of the U-shape. 16. A chain according to claim 13, wherein the outer link portion is an S-shaped plate. 17. A chain according to claim 16, wherein the S-shape is formed from spaced slots extending from opposed edges of the plate, the slots extending in a direction perpendicular to the length of the chain. 18. A chain according to claim 14, wherein there is provided a plurality of apertures. 19. A chain according to claim 18, wherein the apertures are diamond shaped cut-outs. 20. A chain comprising a plurality of inner links interconnected by a connection link having parallel limbs that pass through apertures in the inner links and at least one integral portion interconnecting the limbs. 21. A chain according to claim 20, wherein the connection link is open at one end to define a U-shape. 22. A chain according to claim 20, wherein the connection link is closed at both ends to define a closed loop. 23. A chain substantially as hereinbefore described with reference to figures 1 to 4, figures 5 to 8 and figures 9 and 10 of the accompanying drawings.

Inventors: CHRISTMAS MICHAEL CHARLES, CHRISTMAS, MICHAEL, CHARLES
Applicants: CHRISTMAS MICHAEL CHARLES, RENOLD PLC, CHRISTMAS, MICHAEL, CHARLES
Application year: 1998
Main classification: F16G13
IPC codes: F16G13