Abstract:
A flexible solid plastic torque transmitting insert component having a plurality of exterior lobes and a plurality of interior lobes, each exterior lobe having a selected first width and first and second flat sides, the distance between the respective ends of the flat sides of each exterior lobe defining the first width, each exterior lobe further having a perimeter comprising the first flat side leading into a first radiused corner, the second flat side leading into a second radiused corner, the radiused corners being connected by a central circumferentially disposed segment; and each interior lobe having a selected second width and third and fourth flat sides, the distance between the respective ends of the flat sides of each interior lobe defining the second width; the third flat side leading into a third radiused corner, the fourth flat side leading into a fourth radiused corner, the third and fourth radiused corners being interconnected by a central circumferentially disposed segment.

Description:
RELATED APPLICATIONS: 
     This application is a continuation of U.S. patent application Ser. No. 11/778,512, filed on Jul. 16, 2007, entitled “Flexible Couplings,” now abandoned, which is a continuation of U.S. patent application Ser. No. 10/917,940, filed on Aug. 13, 2004, entitled “Flexible Couplings,” now issued U.S. Pat. No. 7,244,186. U.S. patent application Ser. No. 10/917,940 is a continuation-in-part of application No. 10/911,311, filed on Aug. 4, 2004, now abandoned, which is a continuation-in-part of application Ser. No. 10/107,285, filed on Mar. 26, 2002, now abandoned. The contents of all these foregoing recited applications are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTIONS 
     1. Field of the Invention 
     The invention set forth in this specification pertains to new and improved flexible couplings and, more particularly, to such couplings having advantageous features of both shear and compression style couplings. 
     2. Description of Related Art 
     Flexible couplings have long been used for the purpose of transmitting rotation from one shaft to another. Such couplings are normally used in order to accommodate comparatively minor shaft alignment problems such as are occasionally encountered because of manufacturing or assembly errors. Because of the fact that these devices are widely used and have been known and used for many years, many different types of flexible couplings have been proposed, built, and used. 
     Certain particular flexible couplings have been manufactured in the past so as to include two hubs or hub elements which are adapted to be connected to the shafts joined by the coupling. These hubs are each provided with extending lugs, teeth, or ribs serving as holding means so as to be engaged by corresponding projections on a band-like or belt-like motion transmitting means in order to cause the hubs to rotate in synchronism as one of the shafts is rotated. The bands or belts used in these prior couplings have been flexible, somewhat resilient belts capable of being wrapped around the hubs so that the projections on them engage the holding means on the hubs. 
     A metal band or ring is typically used to retain the belt in position wrapped around the hubs. The interior of the band is shaped and dimensioned so that the band may be slid axially relative to the hubs during the assembly and disassembly of the coupling so that the band fits over the belt when the coupling is assembled so as to conform closely to the exterior of the belt. 
     Some coupling designs have provided a pair of oppositely-disposed axial grooves in the outer surface of the belt and a pair of oppositely-disposed pins in the inner surface of the metal band. The pins are located so as to slide into the grooves as the metal band is installed along a line parallel to the axis of rotation of the hubs. The pins thus position the band and provide a degree of retention. However, if the shafts are grossly misaligned, the metal band will “walk-off” the belt, causing the coupling to come apart. The axial grooves have also been provided with an enlarged central portion such that the pins must be forced through the entrance of the axial groove and then “pop” into place in the central portion to give a tactile indication that the metal band is properly positioned with respect to the flexible belt. 
     In our U.S. Pat. Nos. 6,024,644 and 5,738,585, we have disclosed improved “lock-on” apparatus for improving the retention of the aforementioned metal retainer bands. This improved apparatus employs an axial groove for initially receiving a pin located on the underside of the metal retainer band and a circumferential groove opening into the axial groove and into which the retainer band pin may be rotated. In the embodiments illustrated in the referenced applications, the axial groove is bisected by a radial line which also bisects one of the lobes or projections of the flexible belt. The circumferential groove is relatively short, typically having been selected to be two times the width of the retainer ring pin. In practice, such apparatus must contend with vibrations, harmonics, rotation, misalignment and various stresses and forces on the component parts. 
     SUMMARY 
     The following is a summary of various aspects and advantages realizable according to various embodiments of the invention. It is provided as an introduction to assist those skilled in the art to more rapidly assimilate the detailed design discussion which ensues and does not and is not intended in any way to limit the scope of the claims which are appended hereto in order to particularly point out the invention. 
     Accordingly, disclosed hereafter is a flexible coupling including a first hub having an inner face and a flexible insert having a plurality of exterior lobes and a plurality of interior lobes. A retainer ring is provided having an interior which engages the exterior lobes of the first hub, while a second hub has an exterior surface contoured to engage the interior lobes. The exterior and interior lobes may each have a rounded contour formed between two flat faces, which facilitates torque transmission. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An illustrative and presently preferred embodiment of the invention will now be described in detail in conjunction with the drawings of which: 
         FIG. 1  is an exploded perspective of a coupling according to a preferred embodiment; 
         FIG. 2  is a side view of the coupling of  FIG. 1 ; 
         FIG. 3  is a perspective end view illustrating a hub, insert and retainer components in assembled relation; 
         FIG. 4  is a perspective view of the coupling in the assembled state; 
         FIG. 5  is a side cross view of the coupling in the assembled state; 
         FIG. 6  is a side cross sectional view of an embodiment according to the invention; 
         FIG. 7  is a side cross section view of an embodiment according to the invention; 
         FIG. 8  is a cross section view of an alternate embodiment; 
         FIG. 9  is an enlarged view of a portion of the embodiment of  FIG. 8 ; 
         FIG. 10  is a side view of an alternate embodiment; 
         FIG. 11  is a perspective view of the embodiment of  FIG. 10 ; and 
         FIG. 12  is a perspective view of an alternate embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The coupling of the illustrative embodiment includes a first hub  13 , a flexible insert  15 , a second hub  17  and a retainer member  19 . The first hub  13  includes an interior bore  22 , a first cylindrical segment  21  and a mounting flange  23  having a circular outer edge  25 . The face  27  of the flange  23  has a number of mounting holes  29  therein, each of which lies equally spaced on a circle of lesser diameter than that of the outer edge  25 . Conventional fastening devices such as screw  28  may be used to secure the hubs to respective shafts. 
     The insert  15  is preferably fabricated from a flexible material such as, for example, a suitable urethane, and is preferably split so as to facilitate “wraparound” installation. The outer surface  31  of the insert  15  features a number of equally spaced exterior lobes  33 ,  34 ,  35 ,  36 ,  37 ,  38  projecting therefrom. The lobes, e.g.,  33 , are formed about equally spaced radii extending from the center of the insert  15 . The interior surface of the insert  15  features a number of interiorly projecting lobes  52 ,  53 ,  54 ,  55 ,  56 ,  57 , which, in the embodiment of  FIG. 1 , alternate with the exterior lobes  33 ,  34 , etc. In other words, as one proceeds about the circumference of the insert  15  one encounters a first exterior lobe  33 , then an interior lobe  52 , then a second exterior lobe  34 , then a second interior lobe  53 , etc. 
     The second hub  17  includes a cylindrical segment  43  and an insert-mounting segment or portion  45 . The insert-mounting portion  45  includes a number of wells or receptacles  47  which are shaped and dimensioned to mate snugly with the interior lobes, e.g.,  52 ,  53 , of the insert  15 . The hub  17  is preferably machined as a unitary part from a single piece of metal stock, but of course could be constructed in various other fashions. The second hub  17  further includes an interior bore  44 , typically of circular cross section dimensioned to receive a shaft of cooperating apparatus. 
     The interior  49  of the retainer  19  is specially contoured, shaped and dimensioned to receive and snugly mate with the exterior lobes, e.g.,  33 ,  34 , of the insert  15  when the coupling is in the assembled state. The retainer  19  has a first face  61  ( FIG. 3 ), which receives and passes the insert  15  into mating position with the exterior lobes  33 ,  34 , etc., and a second face  63  ( FIG. 1 ) which includes a depending edge or flange portion  65 , which prevents the insert  15  from passing through the retainer  19 , i.e., holds the insert  15  in a position wherein the insert  15  is preferably encased by the retainer  19 . 
     In the embodiment illustrated, the width “W 1 ,” of the retainer and the width “W 2 ” of the insert are selected such that the face  71  of the insert  15  lies flush with the edge of the first face  61  of the retainer  19 , such that both the insert&#39;s face  71  and the edge  61  lie adjacent the flange face  27  in the assembled state. Thus, in assembly, the retainer  19  “captures” the insert  15  and is then attached to the first hub  13  via a number of fastening devices such as threaded bolts  73 . 
     As shown, for example, in  FIG. 3 , the width W 3  of the insert mating portion  45  of the second hub  17  is preferably selected such that its interior face terminates slightly short of the face of the insert  15 . Thus, the second hub  17  does not protrude through the insert  15  or extend to a point where it might contact the flange face  27  of the first hub  13 . 
     In operation in the assembled state ( FIG. 4 ), the insert is snugly encased and transmits torque and absorbs minor misalignment without exerting axial thrusts on the cooperating shafts to which the first and second hubs  13 ,  17  are respectively attached. Thus, the insert  17  does not tend to exert forces on the hubs  13 ,  17  tending to move them parallel to the central axis  75  of rotation in typical applications. Such forces may cause a hub to move, for example,  15  thousandths of an inch, which is undesirable or unacceptable in certain applications. 
       FIGS. 5-7  illustrate various design considerations according to a preferred embodiment of the invention. According to this illustrated embodiment, the insert  15  exhibits a constant shear section width d 1 . Each exterior lobe, e.g.,  33 , has respective flat sides  81  having a selected length d 2  and a central portion  83  between the two flat sides  81 . The central portion  83  has a circular outer contour of radius R 1 . Adjacent surfaces of the drive ring (retainer)  19  are dimensioned to conform to the shape of the exterior lobe, e.g.,  33 , for example, in incorporating flat sections, e.g.  85  adjacent the flat sides  81  of the outer lobes, the flat sections e.g.,  85  having a length d 21 . The width d 3  of each exterior lobe is the same. 
     Similar to the exterior lobes, each interior lobe, e.g.,  52 , has respective flat sides  87  of equal width d 4  and a central circular portion  89  connecting those sides  87  and having a radius R 2 . The corner to corner width d 6  of each interior lobe, e.g.,  52 , is the same. Finally, the insert includes a split  101  in one of the outside lobes  33 - 38  to provide for wraparound installation. 
     An illustrative dimensioning in inches for a coupling of the size under consideration is as follows:
         R 1 =1.875   R 2 =1.625   d 1 =0.500   d 2 =0.730   d 21 =0.725   d 3 =3.978   d 4 =0.423   d 5 =0.510 (flat section of hub wings)   d 6 =3.325   R 3 =0.100   R 4 =0.100
 
R 4  and R 3  are respectively inside corner lobe radii and outside corner hub wing radii implemented to resist tearing and cutting. As those skilled in the art will appreciate, the dimensioning of the various widths and radii illustrated in  FIGS. 5-9 , of course, varies, for example, with application and size of a particular coupling. Accordingly, as those skilled n the art will further appreciate, for example, the corner to corner width of the interior lobes and/or the exterior lobes need not all be the same dimension and the exterior lobe and interior lobe widths could be equal in various embodiments.
       

       FIG. 6  illustrates various clearances of interest with respect to a coupling according to embodiment of  FIGS. 5-7 . The clearance C 1  is the clearance between the flat sides  87  of the interior lobes, e.g.,  52 , and the adjacent surfaces of the central hub  17 . The clearances C 2  are the clearances between the flat side portions  81  of the exterior lobes, e.g.,  33 , and the adjacent flat portions of the retainer  19 . The clearances C 5  and C 60  are the clearances between the outer and inner diameter of the exterior lobes, e.g.,  33 , and the retainer  19  and hub  17 , respectively. The clearances C 3  and C 4  are the clearances between the outer and inner diameter of the interior lobes, e.g.,  52 , and the retainer  17  and hub  17 , respectively. Illustrative values in inches for these clearances for a coupling, in which the outside diameter of the ring  17  is about 14.72 inches, are:
         C 1 =0.030   C 2 =0.035   C 3 =0.060   C 4 =0.060   C 5 =0.060   C 60 =0.060       
       FIG. 7  illustrates additional dimensions of interest in an embodiment according to  FIG. 5 . In particular, dimension C 8  represents the thickness of that part  65  of the retainer  19  which overlaps the insert  15 . Dimension C 7  represents the clearance range between the opposing faces of the driving and driven hubs  17 ,  13 . The clearance C 6  represents the distance by which the face of the driving hub  17  is set back from the face of the insert  15 . Dimension C 9  represents the clearance between the side face of the insert  15  and the interior edge of the retainer ring  19 . Dimension C 10  represents the clearance range between the face of the insert  15  and the driven hub  13 . Representative dimensions in inches for an illustrative coupling of the size under discussion are:
         C 6 =0.0200   C 7 =0.090-0.310   C 8 =0.5000   C 9 =0.0200   C 10 =0.0200-0.2700       
     Several observations may be made with respect to operation of the couplings according to various embodiments disclosed herein. First, the flat side surfaces on the interior and exterior lobes facilitate torque transmission. The coupling further provides free axial float, illustrated, for example, by clearance ranges C 7  and C 10  in  FIG. 7 , as well as relatively wider width W 2  of the insert and relatively wider wings W 3  of the hub, for example, when compared to features of previous couplings such as ATR Sales&#39; “A” or “M” series. In particular applications, the design enables the driving and driven shafts to be positioned at greater distances from one another than previous designs. In such case, for example, greater thermal growth of shafts can be accommodated than in previous systems. 
       FIG. 8  illustrates an alternate and improved insert  150  captured by an outer retainer member  190  and receiving a second hub  170 . The insert  150  features exterior lobes  133 ,  134 ,  135 , etc. and interior lobes  152 ,  153 ,  154 , etc., which are generally disposed in the same fashion as the respective exterior and interior lobes of the insert  15  (e.g.  FIG. 1 ) but which are contoured differently. In particular, each lobe  133 ,  134 ,  135  has two equal-length straight or flat side segments, e.g.,  201 ,  202 , leading to respective segments  203 ,  204  of a common radius. Respective ends of the two radiused segments are joined by a central circumferentially lying segment  205 . The central segment  205  may be either a straight or slightly curved. This construction provides a locking effect which positively locates the rotating parts under load to limit twist and to increase torsional stiffness and stability. It is desirable to provide as much flat side area, e.g.  201 , as possible because these areas provide the driving surfaces of the coupling, while the radiused corners  203 ,  204  provide resistance which assists in preventing the exterior and interior lobes from coming out of their respective mounting wells when under stress of operation. 
       FIG. 9  provides an enlarged view of a portion of the coupling structure of  FIG. 8 . For the particular coupling illustrated, the space S 1  between the side of each interior lobe, e.g.  152 , and the adjacent side of each spoke of the inner hub  170  may be, for example, 0.060 inches, while the space S 2  between each side of each lobe, e.g.  133 , and each adjacent face of the retainer  190  may be 0.035 inches, for a coupling where the segments of the inner lobes of the insert lie tangent to a circle 13.652 inches in diameter. The angle α between the flat or straight sides of each inner lobe is 60 degrees in the particular illustrative embodiment, Such dimensioning is of course illustrative and will vary with various embodiments as discussed above. Additionally, it may be noted that smaller coupling sizes may not be ideally suited to the use of inserts having the alternate design shown in  FIGS. 8 and 9 . 
       FIGS. 10 and 11  illustrate an alternate embodiment wherein an insert  150  is split at three locations so as to form three separate insert section  161 ,  162 ,  163 . The particular illustrated splits shown in this illustrative embodiment are located at the mid-point (radial centerline) of a respective outer lobe, e.g.  152 . Segmenting an insert  150  as shown in  FIGS. 10 and 11  lowers the effects of hysteresis, permitting the segmented insert  150  to run cooler and prolonging its life. While  FIGS. 10 and 11  illustrate an insert divided into three segments, more or less than three segments could be used in various embodiments. 
       FIG. 12  illustrates an alternative embodiment where two inserts  15  are arranged to be mounted adjacent one another on extended wings  218  of an inner or second hub  217 . An axially lengthened retainer,  219  then captures the two inserts  15  and attaches to the face of another hub  13  in the manner generally illustrated in  FIG. 1 . This design doubles torque handling capability without increasing the diameter of the coupling, which proves useful in applications where space is limited. More than two adjacently mounted inserts may also be provided. 
     Couplings as disclosed above have the advantage of combining advantageous aspects of both shear and compression couplings. In particular, the disclosed couplings normally operate in compression, which prevents exertion of axial thrusts, but can still shear to protect equipment in the event of lock-up or overload, etc. An example is the case of shredding apparatus used to shred recycled material. Occasionally, the material will include prohibited foreign objects which can lock the shredder. In such case, the insert of a coupling according to the disclosed design will shear rather than break the associated equipment. 
     While the present invention has been described above in terms of specific embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. The role of “driving” and “driver hubs” may be reversed and dimensioning adapted to particular sizes and conditions. Thus, the present invention is intended to cover various modifications and equivalent methods and structures included within the spirit and scope of the appended claims.