Abstract:
A coupling between a drive and a driven shaft includes a rigid tube to which are attached in axially spaced apart relation at least two flexible rings of elastomeric material; the outer periphery of each ring is attached to a flange of a connecting hub with each hub mounted or connected to one the shafts; in one form the tube is split axially and is adjustably attachable to the periphery of the rings.

Description:
This application is based on provisional Application Ser. No. 60/162,980 filed Nov. 1, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to flexible coupling devices for shafts to permit and facilitate transmission of torque between a drive and a driven shaft while accommodating misalignment between the shafts. More particularly, the present invention relates to a spool type flexible coupling where the spool may be split so as to enable the coupling to be established between the respective shafts with a greater degree of accommodation of distance variation between the shafts to be coupled and particularly where the shafts&#39; ends are closely spaced and cannot be readily moved. 
     BACKGROUND OF THE INVENTION 
     In the field of flexible couplings, a number of considerations affecting the design of a flexible coupling exist. Among these are the degree of misalignment tolerated, the anticipated torque loads and design constraints relating to the installation allowed. In a number of flexible couplings of the prior art, installation of the coupling has been difficult due to the substantially static character of the coupling members. In other arrangements, only a limited type of elastomeric material could be employed in a coupling to accommodate the torque loads desired. In still other arrangements, the cost of the coupling has been increased, as a result of the complicated design of the flexible elements of the coupling such as is often required in pre-existing power shaft installations. In order to provide simplified structures for the flexible elements of the coupling, the prior art has often relied upon a variation in another portion of the installed coupling elements. This has often resulted in increased weight of the coupling which is undesirable in terms of the efficient transfer of torque from a power source to a driven member. 
     Where the connection flanges of the shafts to be coupled are a significant distance apart, assembly is in general much easier to accomplish than where the shafts are close together. Accordingly, where adequate spacing was provided, the prior art has generally resorted to the use of metal coupling elements in order to reliably transmit torque over a range of operating speeds and loads. In general, elastomeric materials have been avoided and this has complicated the installation procedure as well as increased the cost of such couplings. For closely spaced shafts, however, the use of elastomeric elements has become a necessity due to the confined space available to install and operate the coupling. 
     SUMMARY OF THE INVENTION 
     The present invention avoids the complications of the prior art devices yet provides a flexible coupling, which, in its basic form, accommodates a much broader range of distances between the shafts to be coupled from relatively distant to very closely located shafts yet reliably transmits torque over a satisfactory range and through an increased degree of tolerance for misalignment. 
     In one form of the invention, the coupling spool is split longitudinally and reinforced during assembly by a rigid ring which may be bolted in place during installation. The rigid ring will serve as reinforcement for the split spool and will facilitate installation in positions that would be otherwise difficult or expensive to attempt. In addition, a flexible elastomeric ring may is employed as the flexing member of the coupling and may also be split or formed in arcuate sections and installed on the respective halves of the split spool prior to installation in the coupling. This will also facilitate assembly with closely spaced shafts. 
     In another form, the present invention provides a coupling spool on which are initially movably mounted two coupling sleeves at opposite ends thereof. Each coupling sleeve is provided with a flexible diaphragm in the form of an elastomeric ring which can be coupled directly to a flange of a coupling hub which in turn is mounted on a drive or a driven shaft. The flexible rings are spaced apart a distance that is typically more substantial than in the prior art arrangements. Minor manufacturing changes will enable the coupling of this form of the present invention to accommodate a broad range of distances between the shafts to be coupled. The material of the coupling spool and associated sleeves will be such that these members can be readily adhered together by adhesive binding, riveting or the like. As noted above, the flexible rings carried by the coupling sleeves are preferably made from a flexible elastomeric material that is shaped to accommodate the degree of flexibility needed for a particular application without experiencing sheer stresses or tearing of this material in normal use. With the flexible ring preferably manufactured in an annular shape, a taper is provided where the ring narrows as one moves radially outwardly from the inner periphery of the ring to adjacent the outer rim which is narrower in axial extent. The ring is made by either compression or injection molding to achieve the desired cross-sectional shapes. 
     With the flexible couplings of the present invention, a user a will be able to transmit high torque loads while accommodating high degrees of misalignment. Further, the coupling is characterized by ease of installation in either narrow or extended spaces between the shafts and by a low number of individual parts for assembly. With even widely spaced apart shafts, the flexible coupling of this invention will provide high-speed capability due to the high radial rigidity of the flexible elements. 
     The foregoing and other advantages will become apparent as consideration is given to the following detailed description taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view in elevation of one embodiment showing an arrangement of the elements of the present invention using a split spool; 
     FIG. 2 is a view along lines  2 — 2  of FIG. 1; 
     FIG. 3 is a side view in elevation of an alternate arrangement of the elements of the present invention; 
     FIG. 4 is a side view in elevation of a further arrangement of the elements of the present invention; 
     FIG. 5 is a perspective view in section of a further embodiment of the present invention; 
     FIG. 6A is a side view in elevation of the coupling of the present invention; and 
     FIG. 6B is a view similar to FIG. 6A but with the telescoping feature shown in a different condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, in FIGS. 1 and 2, there is shown an embodiment of the present invention which is adapted for close-coupled shafts, that is, shafts the ends of which are in close proximity to one another and which cannot be moved away from each other than at an unacceptable cost. In this arrangement, the spool is in the form of a split tube  32  which is reinforced by an inner ring  34  and which is held in place by bolts such as at  36  which are evenly spaced about the periphery of the split tube  32 . The ring  34  is preferably located at the midpoint of the tube  32  as shown in FIG.  1 . The ring  34  may be provided in two halves, with two bolts provided to retain each half of the ring  34  in place against the inner surface but bridging over the edges as at  41 ,  43  of the tube halves which it is reinforcing. As shown in the sectional view of FIG. 2, the tube  32  is split longitudinally along its entire length to provide two semi cylindrical bodies  32 ′ and  32 ″. Similarly, the flexible elastomeric rings  16  may each be split into two parts  16 ′ and  16 ″. The radially inner peripheral edges of the ring parts  16 ′ and  16 ″ will each be easily secured to the radially outer peripheral surface of the split tubes  32 ′ and  32 ″. According to this embodiment, the diameter of the split tube  32  is made large enough to accommodate the hubs  26  as shown in FIG.  1 . This will allow a substantially more compact configuration for the elements when achieving coupling between two closely located shaft ends  28  and  30  and yet will provide a coupling with adequate flexibility and tolerance for axial misalignment. The radially extending flanges  22  of hubs  26  are continuous to provide adequate torque transfer through the split rings  16 ′ and  16 ″. The axial extent of the hubs  26  allows it to be easily secured as by welding to the outer surfaces of their respective shafts  28  and  30 . The hubs  22  may be retained on the respective shafts  28 ,  30  by a key  38  placed in a matching groove formed on the interior surface  39  of each hub. Since the spool is provided in two parts  32 ′ and  32 ″, the coupling will be easily reassembled whenever it is necessary to repair or replace elements such as the flexible rings  16 ′ and  16 ″. 
     The assembly of the elements of the coupling of FIG. 1 and 2 is important to obtain the full benefit of the invention. For substantially longer coupling life, it has been found useful to offset the split edges  41 ,  43  of the spool halves  32 ′ and  32 ″ by ninety degrees to the edges  47 ,  48  of the split ring  34  as shown in FIG.  2 . 
     In FIGS. 6A and 6B, the telescoping form of the invention  10  where a spool  12  is interposed between two relatively larger diameter sleeves  14 . Each of the sleeves  14  is identically configured so that a description of only the right hand sleeve will be provided. 
     The sleeves  14  and spool  12  are preferably made of a material such as steel or fiberglass that is easily bonded together with a conventional adhesive such as an epoxy or connected mechanically such as by rivets. Additionally, annular member  16  is readily bonded about its inner opening to the outer peripheral surface of each sleeve  14  as shown with conventionally available adhesives such as epoxies. The annular member  16  is provided equally spaced about its outer rim with bores  18  in which locking bolts  20  are located. A connection hub  26  is provided with an annular flange  22  which is provided with openings for receiving the bolts  20 . Locking nuts  25  are employed to effect the attachment of the coupling flange  26  to the diaphragm  16  as shown. 
     The flexible coupling  10  as described above is particularly adapted to accommodate spaced apart diaphragms  16  for a wide range of distances between the coupling flanges  22 . Thus, by simply selecting a spool  12  of a desired length, a user can accommodate a broad range of coupling distances between shafts. In addition, installation of the coupling  10  can be easily accomplished since the fastening of the spool  12  to one or both of the sleeves  14  can be accomplished after the elements of the coupling  10  are in place. 
     As will be apparent from FIG. 3, where a telescoping facility is not used, the spool  12  may be employed alone as shown in FIG. 3 to provide a flexible coupling employing spaced apart flexible, elastomeric rings  16  which are securely bonded to the outer periphery of the spool  12  adjacent the ends of the spool  12 . The use of a suitable elastomeric material such as polyurethane elastomer for the diaphragm rings  16  makes it particularly easy to install. The rings may each have cross sections that taper non linearly from their radially inner portions to their radially outer portions. 
     A modification of the coupling of FIG. 1 is shown in FIG. 4 where a spool member  40  surrounds the coupling elements including two hubs or sleeves  42  and  44 . The flexible, elastomeric members  16  are bonded at their interior periphery directly to the outer periphery of each of the hub members  42  and  44 . The outer periphery of each of the members  16  are similarly bonded to the inner periphery of the reinforcing rings  46  and  48 . The spool  40  may be either bonded or riveted as through holes  50  to the outer periphery surface of the rings  46  and  48 . The shafts to be coupled will be inserted into the interior of a hub  42  to an extent to allow the second shaft to be inserted as through end  52  into hub  44 . The shafts will then be fixed to their respective hubs  42 ,  44  by welding, bolting, riveting or the like. The spool  40  may be split parallel to its longitudinal axis to facilitate installation where the shafts are too closely placed together at the site to allow easy installation. 
     Referring to FIG. 5, there is shown a perspective, sectional view of a further modification of the invention where a split spool  50  is employed in a configuration similar to that of FIG. 4 but with the hubs projecting externally of the ends of the spool  50 . Again, the elastomeric elements  16  are bonded to the inner or periphery of reinforcing rings  56 , 58  and to the outer periphery of the shaft mounting hubs  52  and  54 . Again, the use of a split spool facilitates installation without sacrificing the integrity of the coupling or its torque transmission ability. In addition, the rings  56 , 58  may be positioned at positions located axially inwardly of the outer edges  60  of the spool  50  sections by the provision of alternate fastener bores  62  located, as shown, inwardly of the edges and the outermost holes in which the screws, two of which are indicated at  64 , are positioned. A plurality of sets of bores  62  may be provided to expand the range of adjustability. 
     The use of spaced apart flexible rings as described in the foregoing embodiments increases the misalignment tolerated by the couplings while allowing a significant latitude in installation. Moreover, the couplings described above will provide high torque transmission while retaining the advantages of lightweight installations.