Abstract:
A coupling system is disclosed for coupling rotating elements such as a flywheel and a shaft, pairs of shafts, and so forth. A flexible element is captured by a hub. The flexible element may be coupled to a first rotating member, such as a flywheel. The flexible element may be generally disk-like or tire-like. The hub presents an intermeshing interface, such as a series or recesses in a face thereof. A coupling member on the second rotating member has protruding extensions generally parallel to an axis thereof. The extensions intermesh with or engage the recesses of the hub to enable the assembly to be finally installed by stabbing motion of the extensions into the recesses.

Description:
BACKGROUND 
       [0001]    The current invention relates to the field of mechanical couplings. More specifically, the invention relates to a system that flexibly couples a shaft of one rotating member to a shaft or flywheel of another rotating member. 
         [0002]    Mechanical systems often consist of a number of energy converting devices. A few examples of such devices include motors, pumps, alternators, generators, and turbines. These devices are often physically connected to one another via a mechanical coupling to realize the potential of one energy source by converting it into a more useful form. For example, the rotating shaft of an internal combustion engine may drive a flywheel that is, in turn, coupled to the shaft of a pump or other driven device. The mechanical coupling serves to transfer the kinetic energy generated by the engine to drive the load, particularly through transmitting torque to the load during operation. 
         [0003]    A variety of mechanical couplings are known and commercially available for connecting one rotating member to a second rotating member. All of these couplings have limitations that impact their implementation and performance when used in a mechanical system. One limitation is that the couplings can be bulky and require more operating space than is available. A low profile coupling that can operate in a space constrained environment would be desirable. 
         [0004]    Another limitation is that existing coupling systems are often difficult to install and implement, as well as to service, thus leading to a longer installation and downtime. In a particular application involving engine driven equipment, installation of a flywheel-mounted coupling element, along with mounting of its interfacing components on a driven shaft can be extremely tedious and time-consuming. This is particularly the case when the application calls for the driven load (such as a pump) is supported on the engine itself, as the coupling elements will be at least partially surrounded by support structures and therefore difficult to access. A coupling that is preassembled and easy to install would be preferable over a complex coupling with multiple parts. 
         [0005]    A further limitation results from the misalignment of the coupled shafts. This misalignment can be both axial (offset centerlines) and angular (non-perpendicular faces or misaligned axes of the driving and driven machines). Practically speaking, this misalignment can never be completely eliminated. Those skilled in the art will appreciate the advantages of a coupling device that can still function even when the shafts or other rotating elements are not in perfect alignment. Some commercially available couplings address this issue but often do so at the cost of reduced torque carrying capacity. Such couplings often increase the internal clearance in the load bearing members of the coupling to allow for the misalignment. This can, however, reduce the life of the coupling and its ability to transfer torque efficiently. A coupling that could allow for this misalignment without sacrificing torque carrying capacity would be desirable. 
         [0006]    Another issue arises as a result of dynamic imbalances inherent in any rotating device. At high rotations per minute (RPM) these imbalances can result in severe lateral, torsional, and axial vibrations which are then transmitted through the system via the coupling. These vibrations cause the system to run less efficiently and can also damage vibration sensitive devices, such as bearings. A coupling that can dampen and isolate vibration, thereby preventing transmission, would be of particular benefit. 
         [0007]    Finally, many mechanical systems operate in environments where human interaction is common. Rotating components are therefore often enclosed by shields or other covers or mounted to an external housing. These covers often complicate the assembly process and make direct access to the coupling system difficult and taxing. Current commercially available couplings often require the user to complete the coupling mechanism after these covers are in place. This is particularly problematic when the coupling is only accessible through an access port of very limited dimensions. A coupling system that has an intermeshing interface that could be independently installed on the respective rotating components and then blindly stabbed together would be advantageous. The blind stab capability would eliminate the need for the user to complete the coupling interface through the tiny access port and allow for much more efficient assembly, disassembly, and servicing. 
       BRIEF DESCRIPTION 
       [0008]    The present invention offers a solution to all of the issues and problems that currently limit other commercially available mechanical couplings. The invention generally consists of two parts, a flexible hub assembly and a coupling element. The flexible hub assembly is a pre-assembled component that is easily installed and implemented on a first rotating member, thus reducing installation time. The assembly is low profile and can operate in a space-constrained environment. The hub assembly has a flexible element that allows for misalignment between the rotating members as well as functioning as a dampener for vibration isolation. Furthermore, the hub assembly uses elastomeric inserts that allow for reduced internal clearance in the coupling system. The coupling element is adapted to be secured to a second rotating member, and stabbed or axially mated with the hub assembly. 
         [0009]    The net effect is that the system has a higher torque carrying capacity without over constraining the mechanical system or sacrificing coupling life. The system is blindly stabbable and is engaged with very little user interaction. The end user only needs to install the flexible hub assembly and coupling element onto their respective rotating members and then simply slide the two devices together. No further assembly is required eliminating the need to complete the coupling when direct access might be limited. All of these benefits reduce the time and difficulties in coupling one mechanical system to another without sacrificing performance or safety. 
     
     
       DRAWINGS 
         [0010]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0011]      FIG. 1  is a perspective view of an exemplary flexible coupling assembly in accordance with aspects of the invention, illustrating the flywheel, flexible hub assembly, coupling element, and driven shaft; 
           [0012]      FIG. 2  is a sectional view of the flexible coupling assembly of  FIG. 1 , sectioned along line  2 - 2 , illustrating the internal elements of the coupling system; 
           [0013]      FIG. 3  is a sectional view illustrating an alternative embodiment of the inventive coupling system designed for coupling two shafts to one another; 
           [0014]      FIG. 4  is a sectional view illustrating a second alternative embodiment of the inventive coupling system. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Turning now to the drawings,  FIG. 1  illustrates a flywheel  10  having a front face  12  and rotating about an axis or centerline  14 . The flywheel  10  represents the output interface of the first mechanical device. The flywheel  10  might be attached to an engine, for example, and driven by the engine during operation. The flywheel  10  has a plurality of threaded holes  16  located on the front face  12 . The threaded holes  16  are located at a specified distance from the centerline  14  so as to permit securement of the coupling system as described below. 
         [0016]    It should be noted that where, in the present discussion, reference is made to a driving or a driven element, this is for convenience only. As will be appreciated by those skilled in the art, the couplings and systems of the present invention may be used in a variety of contexts and with power or torque flow in the directions indicated here, or in an opposite direction. 
         [0017]    A flexible hub assembly  18  has a mating surface  20  that contacts the front face  12  of the flywheel  10 . The flexible hub assembly rotates about an axis or centerline  22 . The flexible hub assembly  18  has a number of elements, each of which will be discussed in more detail below, particularly in relation to  FIG. 2 . In general, the assembly includes a flexible element  24  that defines an outer flange  26  with a plurality of holes  28  extending therethrough. The holes  28  are located at a distance from the hub centerline  22  such that they align with the threaded holes  16  in the flywheel  10 . Fasteners  30  are used to secure the flexible hub assembly  18  to the flywheel  10 . The flexible hub assembly  18  can be delivered as one piece and quickly installed on the flywheel by simply engaging the fasteners  30  into the threaded holes  16  of the flywheel  10 . The disk-like shape of the flexible element  24  reduces the overall profile of the assembly, allowing it to be installed and implemented in space constrained environments. The flexible element  24  is made from a compliant elastomeric flexing material such as a reinforced natural rubber or neoprene. Those skilled in the art will readily appreciate that the invention is not functionally limited to these specific material choices and any suitable compliant material could be used for the flexible element  24 . 
         [0018]    An external flange  32  secures the flexible element  24  to a hub  34 . Clamping fasteners  36  load against the front face  38  of the external flange  32 . The external flange  32  and the other elements used to secure the flexible element  24  to the hub  34  will be described in more detail in the discussion of  FIG. 2  below. 
         [0019]    The hub  34  has a front face  40  with a plurality of recesses  42  extending into the hub, generally in a circular pattern. The configuration of the recesses  42  provides for a plurality of inner keys  44  and outer keys  46 . A plurality of inserts  48  having slots  50  are placed in the recesses  42  and engage the inner keys  44  and outer keys  46 . This interface radially locates the inserts  48  in place allowing for the coupling to be blindly stabbed together during assembly, as described below. In a present embodiment, the inserts  48  are self constrained, that is, they fit snuggly into the recesses  42  of the hub  34 , facilitating assembly of the coupling system when placed in service. Those skilled in the art will appreciate that the number and geometry of the hub  34  and inserts  48  could be varied from those shown and provide the same functionality. For example, the plurality of inserts  48  could be replaced with a one piece insert ring resulting in the same self constrained locating feature. The present embodiment only illustrates one geometry configuration for the self constrained insert  48  but is not functionally limited to this geometry. Furthermore, the inserts  48  used in the present embodiment are made of rubber or some other compliant material. This material choice results in a conformable cavity  52  eliminating the need for close internal clearance in the coupling. The net effect is that the coupling can transfer more torque and permit somewhat greater misalignment without sacrificing durability. Moreover, the hub  34  is shown with an inside diameter  54  which has the benefit of reducing the weight of the assembly. 
         [0020]    The driven shaft  56  rotates about an axis or centerline  58  and is configured to engage a coupling element  60 . The coupling element  60  has an inside diameter  62  with an internal key feature  64  that aligns with a key feature  66  in the driven shaft  56 . A key  68  is used to transmit torque from the coupling element  60  to the driven shaft  56 . The coupling element  60  has an outside diameter  70  with threaded holes  72  extending therethrough into the inside diameter  62 . One or more set screws  74  are used to axially secure the coupling element  60  onto the driven shaft  56 . Extensions  76  protrude axially from the front face  78  of the coupling element  60 . The extensions  76  are configured to engage the cavities  52  formed by the recesses  42  and inserts  48 , creating an intermeshing interface. Here again, those skilled in the art will readily appreciate that the number and geometry of the components of this intermeshing interface can be changed and still provide the same functionality. For example, the extensions  76  could be configured to protrude radially from the outside diameter  70  of the coupling element  60  rather than axially as shown. Also the intermeshing interface of the current embodiment could be reversed by having the extensions  76  on the hub  34  and the cavities  52  on the coupling element  60 . The present embodiment only illustrates one geometry configuration for this intermeshing interface, but the invention is not functionally limited to this geometry. 
         [0021]      FIG. 2 . is a sectional view further illustrating the internal elements of the flexible hub assembly  18  and the manner in which the flexible element  24  is coupled to the hub  34 . A protective cover  102  is shown that was not illustrated in  FIG. 1 . As shown, an internal flange  80  is positioned opposite the external flange  32 . The internal flange  80  has a front face  82  having a plurality of threaded holes  84  extending therethrough. The clamping fasteners  36  pass through the hub  34  and engage the threaded holes  84  in the internal flange  80 . The internal flange  80  has an inside diameter  86  that engages the outside diameter  88  on the hub, radially locating the flange. The hub has a stepped diameter  90  with a plurality of through holes  92 . The external flange  32  has mating through holes  94  allowing the clamping fasteners  36  to pass therethrough. This configuration has the mechanical benefit of keying the hub  34  to the external flange  32  and internal flange  80  via the clamping fasteners  36 . Those skilled in the art will appreciate that passing the clamping fasteners  36  through the stepped diameter  90  is not required but is implemented to increase the torque carrying capacity of the coupling system. 
         [0022]    The flexible element  24  is coupled to the hub  34  via the clamping force created by the clamping fasteners  36 . In particular, the inner periphery  98  of the flexible element  24  is captured by the clamping force created between the front face  82  of the internal flange  80  and the back face  100  of the external flange  32 . The external flange  32  has an inside diameter  96  that engages the outside diameter  88  on the hub  34 , radially locating the flange. 
         [0023]    The blind stab flexible coupling system is ideal in situations where a protective cover  102  or other structure does not allow or limits access to the flexible hub assembly  18 . In a typical engine flywheel application, the system is “blindly” stabbed together by installing the flexible hub assembly  18  and protective cover  102  onto and around the flywheel  10 . The coupling is then engaged by axially moving the pre-installed coupling element  60  towards the installed flexible hub assembly  18  and blindly stabbing the coupling together, as indicated generally by reference numeral  104 . The coupling element  60  approaches the flexible hub assembly via an opening  112  in the protective cover. Those skilled in the art will appreciate the simplicity and ease of engaging the current invention and its advantages over a system that requires the user to access the coupling after the two devices are placed adjacent one another within a cover, support assembly or other surrounding structure. It is especially advantageous where direct access to the coupling is limited due to a protective cover  102 . 
         [0024]    Once engaged, the coupling system transfers the flywheel torque  106  to the flexible hub assembly  18  via the flexible element  24 , resulting in a hub assembly torque  108 . The hub assembly torque  108  is then transferred to the driven shaft  56  via the coupling element  60 , resulting in a drive shaft torque  110 . The driven shaft torque  110  is then transferred from the coupling element  60  to the driven shaft  56  via the key  68  thus completing the coupling function. The compliant nature of the flexible element  24  allows for the misalignment of the flywheel centerline  14  to the driven shaft centerline  58 . The flexible element  24  also dampens and isolates vibrations to or from the flywheel  10  to the driven shaft  56 . Also, as discussed above, the inserts  48  reduce coupling internal clearance allowing for optimum conversion of flywheel torque  106  to drive shaft torque  110 . 
         [0025]      FIG. 3  is a sectional view of a first alternative embodiment of the current invention. A first rotating member  114  is shown as a shaft rather than the flywheel  10  illustrated in  FIG. 2 . The flexible element  116  is tire-like and is coupled to the hub  34  in the same manner described above. Tire-like flexible elements  116  of the type shown are commercially available under the designation “Para-Flex”, from Rockwell Dodge, a Rockwell Automation Company, located in Greenville, S.C. In this embodiment, a coupling element  60  is attached to the driven shaft  56  or second rotating member, and engages the hub  34  in the same manner as discussed above. A coupling mechanism  118  captures the flexible element  116  and is secured to the first rotating member  114 . The configuration of the various components, and the manner in which the system may be stabbed following assembly on the shafts is generally similar to the arrangement described above. 
         [0026]      FIG. 4  is a sectional view of a second alternative embodiment of the current invention. The flexible element  116  is shown in the tire-like configuration as illustrated in  FIG. 3 . The coupling mechanism  118  shown in  FIG. 3  is replaced by a combination of a second hub  120  and second coupling element  122 . The second coupling element  122  is secured to the first rotating member  114  and engages the second hub  120  in same manner as the first coupling element  60  engages the first hub  34 , thereby transferring torque to the driven shaft  56 . Those skilled in the art will appreciate that this embodiment does not functionally differ from either of the previously presented embodiments insomuch as the components can be easily pre-assembled on their respective drive and driven elements, then stabbed together for final assembly. 
         [0027]    While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.