DRIVE CHAIN

Abstract: A link (1) for a roller chain, of substantially rectangular transverse cross-section and pivotally connectable at each end to an identical link. Each of the link's four sides is provided with a tooth-engaging recess which extends over its length, thus enabling the link to have a pitch substantially twice that of a standard roller chain. By comparison, prior art multi-planar roller chain links require a pitch substantially four times that of standard roller chain. The link may be formed from a continuous annulus, flattened and bent into a "U" shape to form four bights (2) to locate a pair of pivot pins (3) whose axes of rotation are normal to each other.

Description: DRIVE CHAIN THIS INVENTION relates to chain links and more particularly to the construction of a link for a roller or other drive chain which enables power to be transmitted from one cog or sprocket to another such in situations where the driving and driven cogs or sprockets are disposed in different planes. Drive chains for the transmission of power from a cog or sprocket to another in the same plane are old; for example, the chain-driven "safety" type of bicycle first appeared in England in about 1885. However, a demand developed for drive chains adapted to transmit power, via co-acting cogs or sprockets, without loss, in situations in which the driving and driven shafts may be in any axial ' relationship to each other. It was soon realised that it was necessary to construct links for such a chain which had, at one end, an axis of rotation normal to that at the other end. A disadvantage of a chain so constructed is that it can bend in a first plane only at every second link and, in a second plane normal to the .first plane, at every alternate other link; thus, a "stiff" chain results. Chains having alternate pivots substantially normal to each other have been proposed, for example, in U.S. patent No. 3,810,358. This describes and claims a chain suitable for use with ships' anchors, in which each link comprises a bar bent into U-shaped configuration, bridged at the extremities by a cylindrical pin of a length substantially equal to its diameter and which "mates" under load with the U-shaped bar member of the next adjacent link the axis of symmetry of which is at 90 degrees to the firstmentioned link. It is the purpose of this anchor chain to eliminate, or mitigate, failure of the chain at the bearing faces provided by the cylindrical pins. Further United States patent No. 3,905,304 discloses a chain for a conveyor system having a plurality of links and a plurality of connecting bodies arranged alternately along the length of the chain. Each body is connected to a pair of links for pivotting movement relative thereto about respective mutually perpendicular axes, each link comprising a pair of link elements arranged side-by-side. Each body has a projecting lug which limits pivotting movement of one link relative to the body so that such link cannot pivot through an angle of 180 degrees from the position occupied when the chain is straight; the lug also prevents assembly of the chain with an incorrect pitch. Conveyor chains and links of a generally like kind are also disclosed in the specifications relating to Australian patents Nos. 145,263 and 232,834. It is an object of the present invention to overcome the above and other disadvantages of the prior art roller chains by the provision of roller chain links, and roller drive or conveyor chain composed of a plurality of such links, which, in co-operation with complementary sprockets of known construction, result in positive power transmission in situations where the driving and driven shafts may be in different axial angular relationships to each other. Thus, in accordance with the present invention there is provided a link for a roller chain, the link being pivotally connectable to identical roller chain links at either end of said link, so that the two pivots of the link have axes of rotation normal to each other; characterised in that each of the four longitudinal sides of the link is provided with an elongated recess and adapted for the entry of a co-acting sprocket tooth, openings of opposed pairs of recesses being disposed normal with respect to each other. In a second aspect, the above-described roller chain link s formed from an annulus of material of rectangular cross-section, the annulus being flattened into a shape having rounded ends and parallel straight sides, and the flattened shape bent into a U-shaped configuration having limbs of equal lengths; a sleeve member affixed in the bight of the U-shaped link; and a pin, of diameter such as to fit within the bore of the sleeve member, mounted between the rounded free ends of the limbs. In a further aspect, the roller chain link is formed from an elongated blank having rounded ends, an aperture adjacent each of the ends and an elongated slot extending along the longitudinal axis of the blank intermediate the apertures, the blank being bent into a U-shaped configuration having limbs of equal lengths; a sleeve member affixed in the bight of the U-shaped blank; and a pin', of diameter such as to fit within the bore of the sleeve member, mounted between the two apertures. In either embodiment, the pin may be removable in order to facilitate the connecting of adjacent links and. here may also be provided an outer sleeve which is adapted to rotate freely- about the sleeve member. In yet a further aspect, the present invention may consist in a roller chain composed of a plurality of the above-described links. Certain preferred embodiments of the invention will now be described, by way of example only and with reference to Figures 1 to 5 of the accompanying drawings in which:- Figure 1 is an isometric view of a roller chain link in accordance with the present invention; Figure 2 is an isometric view of a portion of a chain composed of the links of Figure 1; Figure 3 is a schematic illustration of a sprocket engaged with a roller chain of the inventive links; and Figures 4, 5 and 6 show alternative preferred constructions of the links, while Figures 7 and 8 show prior art roller chain link blanks, to be more fully dealt with hereinafter. Figure 1 shows an inventive roller chain link, generally referenced 1, which is formed from an annulus of rectangular-sectioned rod by an operation later to be described with reference to Figure 4. As will be observed, link 1 is of substantially rectangular transverse cross-section and each of its four sides has in it a slot, formed as a consequence of its geometry, which is adapted to receive therein a co-acting tooth of a cog or sprocket. In the bights 2 of the wide end of the link is affixed - as by welding - a sleeve member. which has in it a bore 5 of a diameter such as to freely accommodate within it a pin such as 3. In the bights 2 of the narrow end of this U-shaped link, that is to say, between its rounded free ends, is affixed a pin 3 during assembly of a chain formed from such links - again as by welding. Each pin 3 and sleeve member 4 may be secured in their respective bights by means other than welding; for example, the bights may be deformed or crimped around more than one half of the circumference of the pin or sleeve member, either with or without additionally securing the bights in circumferential grooves or rebates in them. As will be appreciated, the dimension - represented by 6 - of the link dictated by the length of pin 3 is greater than the dimension 7 dictated by the length of sleeve member 4. The configuration of the inventive links forming a chain is substantially 90 degrees from one link to its neighbour. This will be clearly seen from Figure 2, which illustrates a portion of a roller chain composed of the links of Figure 1. Chains composed of those links can bend in two planes, although, of course, only every alternate link can pivot in the desired direction. This construction permits the employment of known sprockets, as shown schematically in Figure 3, in which figure a sprocket 8 is mounted on a shaft 9 and may be either a driving or a driven sprocket or cog. The sprocket is provided with teeth 10 on its periphery, adapted to engage the outer surface 11 - see Figures 1 and 2 - of each sleeve member 4. In a preferred embodiment, each sleeve member may be provided with an outer 'sleeve adapted to rotate freely about the sleeve member., ideally this outer sleeve is fabricated from hardened steel. Also, the pins may well be removable in order to facilitate the connecting of adjacent links. Because every alternate link of the roller chain cannot pivot in a desired direction, an appropriate gap or void 12 is provided between each pair of teeth 10 on the periphery of sprocket 8. Those gaps 12 serve to accommodate those links which are connected at each end by a pin/sleeve member arrangement, the axis of rotation of which is normal to shaft 9; these links are schematically shown as squares 13. A roller chain composed of links in accordance with the present invention may be passed over any desired portion of the periphery of a sprocket. As the angle between the linear direction of the "incoming" chain and that of the "outgoing" part of it can be varied as desired, the use of two idler sprockets can result in positive drive being transmitted between a sprocket on a driving shaft and another on a driven shaft, the two shafts being in any desired spatial relationship. Figures 4 and 5 are largely self-explanatory and relate to two ways of manufacturing links according to the invention. Figure 4 involves the flattening of an annulus (14) of rectangular-sectioned rod into a shape 15 having- rounded ends 16 and parallel straight sides 17. Flattened shape 15 is then bent into a U-shaped configuration having limbs of equal lengths, and has affixed to it a pin and sleeve member as shown in Figures 1 and 2. Figure 5 illustrates a stamped-out blank from which an inventive link may be made, analogous to that shown in Figures 1, 2 and 4. - "Figure 6 illustrates an embodiment made of cast metal. Figures 7 and 8 illustrate prior art roller chain link blanks; in these links, sprocket teeth can engage with the links only in different sections thereof; in other words, each of the four sides of the link- does not have a tooth-engaging slot extending over its whole length the openings of opposed slots being normal to each other. It being appreciated that pitch is normally defined as the distance between the centers of two adjacent teeth on a sprocket, in multi-planar chains, "pitch" means the distance between the centers of two adjacent teeth bearing against pins whose axes are parallel. The links of such multi-planar chains as are presently in use, as shown in Figures 7 and 8, while having adjacent pivots at right angles, have the sides adjacent the said rollers closed in much the same manner as standard roller chain and have a central plate to join the two sets of closed sides together. Such known links, which can only operate in pairs in relation to a sprocket in a given plain, are susceptible to shear failure under tension and also each pair has a "pitch" nearly four times that of a standard roller chain. This means that sprockets of far greater diameter are necessary in order to avoid chordal action, limiting use to conveyors and other low tension applications. By comparison, the present invention provides a pair of links having a "pitch" only very slightly longer than twice that of standard roller chain of equivalent specification. These links are particularly well suited to high tension applications. The key to the success of the present invention in halving the "pitch" of a pair of links of this type of chain is the provision in each link of sprocket tooth access along substantially the length of the link from all four sides of the link. From the above-going, the reader will readily appreciate that roller chain links made in -accordance with the present invention will provide the public with a new or much-improved article or, at the very least, offer to it a useful and attractive choice.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS;- 1. A link for a roller chain, said link being pivotally connectable to identical roller chain links at either end of said link so that the two pivots of the link have axes of rotation normal to each other; characterised in that each of the four longitudinal sides of said link is provided with an elongated recess and adapted for entry of a co-acting sprocket tooth, openings of opposed pairs of recesses being disposed normal with respect to each other. 2. The link as claimed in Claim 1, said link being formed from an annulus of material of rectangular cross-section, said annulus being flattened into a shape having rounded ends and parallel straight sides, and said flattened shape being bent into a U-shaped configuration having limbs of equal lengths; a sleeve member affixed in the bight of the U-shaped link; and a pin, of diameter such as to fit within the bore of said sleeve member, mounted between the rounded free ends of said limbs. 3. The link as claimed in Claim 1, said link being formed from an elongated blank having rounded ends, an aperture adjacent each said end and an elongated slot extending along the longitudinal axis of said blank intermediate said apertures, said blank being bent into U-shaped configuration having limbs of equal lengths; a sleeve member affixed in the bight of the U-shaped blank; and a pin, of diameter such as to fit within the bore of said sleeve member, mounted between the said two apertures. 4. The link as claimed in Claim 1, said link being formed by a metal casting process. 5. The link as claimed in Claim 2, wherein there is provided an outer sleeve adapted to rotate about said sleeve member. 6. The link as claimed in Claim 3, wherein there is provided an outer sleeve adapted to rotate about said sleeve member. 7. The link as claimed in Claim 4, wherein there is provided an outer sleeve adapted to rotate about said sleeve member. 8. The link as claimed in Claim 2, wherein said pin is removable, to facilitate the connecting of adjacent links. 9. The link as claimed in Claim 3, wherein said pin is removable, to facilitate- the connecting of adjacent links. 10. The link as claimed in Claim 4, wherein said pin is removable, to facilitate the connecting of adjacent links. 11. A roller chain composed of a plurality of links as claimed in Claim 1.

Inventors: FULLER EDWARD CHARLES, FULLER, EDWARD, CHARLES
Applicants: FULLER EDWARD CHARLES, FULLER, EDWARD, CHARLES
Application year: 1985
Main classification: F16G15
IPC codes: B21L9, B22D25, F16G13, F16G15