Abstract:
A power transmission coupling that includes a drive shaft hub selectively connectable to a driven shaft hub. The drive shaft hub includes a number of ball bearings disposed within bores in the drive shaft that are selectively engageable within a groove disposed on the driven hub. The bearings are selectively locked within the groove by a sleeve movable disposed around the drive hub over the bearings. The drive hub also includes a key secured thereto that is selectively received within notches or apertures formed in the driven hub to mechanically engage the drive hub with the driven hub for effective power transmission via the coupling.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 61/468,695, filed on Mar. 29, 2011, the entirety of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to power transmission systems, and more specifically to a coupling for use in a power transmission system. 
     BACKGROUND OF THE INVENTION 
     Many different types of machines operate by transferring power from a power source in the form of rotational motion to a driven element to assist in performing the particular function of the machine. In many machines that operate in this manner, a rotating drive shaft rotates a driven shaft that is operably connected to the drive shaft. 
     In order to couple a drive shaft to a driven shaft, many different types and constructions for the power transmission couplings have been developed. The coupling securely engages the drive shaft to the driven that such that the rotation of the drive shaft is effectively transferred to the driven shaft so that the machine including the drive and driven shafts can operate to perform the desired function. 
     One concern with couplings of this type is the ability of the coupling to be easily and quickly engaged and disengaged, such as when the machine needs to be serviced, without the need for additional tools or implements to perform that function. In particular, many prior art couplings incorporate linear splined engagement mating surfaces, which is a tedious and difficult mechanism for interconnecting the coupling for its intended use in securing the drive and driven shafts to one another. A known disadvantage of splined interconnecting is the need for tight tolerances between mating surfaces to eliminate the possibility of vibration within the coupling assembly as it rotates. This need for tight tolerances predicates a deliberately precise engagement of the hubs, which is a detriment to the operator while attempting to support, control and install the driving hub and drive shaft to the driven hub. 
     Furthermore, in conjunction with radial groove (on the driven hub)-to-ball bearing-capturing of the coupling hubs, another disadvantage of splined interconnecting is that the entire set of linear splines must re-engage upon passing by the radial groove, because the radial groove interrupts the splines. Even slight misfit or misalignment of mating splines then causes considerable difficulty when attempting to complete the connection of the hubs. 
     Thus, there exists a need for a coupling construction that provides a simple and easy to engage/disengage construction for the selective interconnection of a drive shaft and a driven shaft for power transmission therebetween. 
     SUMMARY OF THE INVENTION 
     Therefore according to one aspect of the present invention, a transmission coupling assembly is provided that can be quickly and easily engaged and disengaged from the driven shaft and/or the drive shaft without the need for any tools or additional implements. The coupling overcomes the aforementioned disadvantages as it utilizes smooth diameter mating surfaces to engage and center the coupling hubs and only one torque transmitting member that must engage instead of many splines. The cost effectiveness of manufacturing by these means versus the use of splined mating surfaces is evident as well. The coupling is also able to securely hold the drive and driven shafts in engagement with one another to maintain an effective transmission of power from the drive shaft to the driven shaft. 
     According to another aspect of the present invention, the coupling includes a driven shaft hub including a number of apertures disposed therein. These apertures are alignable with engagement structures on a drive shaft hub. When the driven shaft is engaged with the drive shaft, the apertures in the driven shaft hub are positioned in alignment with the engagement structures to interconnect the driven and drive shaft hubs with one another to enable power transmission through the coupling. 
     According to a further aspect of the present invention, the drive shaft hub includes a locking mechanism that can be selectively disengaged when it is necessary to engage or disengage the driven shaft hub from the drive shaft hub. The locking mechanism is biased in order to maintain the locking mechanism in the locked configuration until it is desired to disengage the mechanism. 
     Other aspects, advantages and features of the present invention will be made apparent from the following detailed description taken together with the drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate the best mode currently contemplated of practicing the present invention. 
       In the drawings: 
         FIG. 1  is a cross-sectional view of a first embodiment of the coupling assembly of the present invention; 
         FIG. 2  is a side plan view of a driveshaft hub of the assembly of  FIG. 1 ; 
         FIG. 3  is a front plan view of the driveshaft hub of  FIG. 2 ; 
         FIG. 4  is a rear plan view of the driveshaft hub of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view along line  5 - 5  of  FIG. 3 ; 
         FIG. 6  is a partially broken away, cross-sectional view of a bearing engaged with the driveshaft hub of  FIG. 2 ; 
         FIG. 7  is a front plan view of a driven shaft hub of the assembly of  FIG. 1 ; 
         FIG. 8  is a side plan view of the driven shaft hub of  FIG. 7 ; 
         FIG. 9  is a cross-sectional view along line  9 - 9  of  FIG. 7 ; 
         FIG. 10  is a side plan view of a locking sleeve of the assembly of  FIG. 1 ; 
         FIG. 11  is a front plan view of the sleeve of  FIG. 10 , 
         FIG. 12  is a cross-sectional view along line  11 - 11  of  FIG. 10 ; 
         FIG. 13  is a front plan view of a key of the assembly of  FIG. 1 ; and 
         FIG. 14  is a side plan view of the key of  FIG. 13 . 
         FIG. 15  is an isometric view of the assembly of  FIG. 1 ; 
         FIG. 16  is a front plan view of a second embodiment of the coupling assembly of the present invention; 
         FIG. 17  is a cross-sectional view along line  17 - 17  of  FIG. 16   
         FIG. 18  is a front plan view of a driven shaft hub of the assembly of  FIG. 17 ; 
         FIG. 19  is a side plan view of the driven shaft hub of  FIG. 18 ; 
         FIG. 20  is a cross-sectional view along line  20 - 20  of  FIG. 18 ; 
         FIG. 21  is a front plan view of a key of the assembly of  FIG. 16 ; 
         FIG. 22  is a side plan view of the key of the assembly of  FIG. 16 ; and 
         FIG. 23  is a top plan view of the key of the assembly of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the drawing figures in which like reference number designate like parts throughout the disclosure, a power transmission coupling assembly is indicated generally at  10  in  FIG. 1 . The coupling assembly  10  is a mechanical, quick-disconnect power transmission, or drive shaft coupling. Specific to this design is the ability to quickly connect and disconnect the individual halves or hubs  12 , 14  of the coupling  10  without the use of tools, and only the use of the operator&#39;s hands. 
     In one embodiment for the coupling assembly  10 , the coupling  10  is for use in a metal strip processing roll coater machine (not shown). The roll coater incorporates cylindrical rollers (not shown) which apply a variety of liquid coatings to metal strip as it passes through the machine. Each roller is driven by a motor/reducer combination (not shown) which is affixed to a drive shaft (not shown). The coupling  10  joins the drive shaft to the roller, such as to a central driven shaft or journal (not shown) of the roller. 
     Operators of a roll coater must frequently disconnect and reconnect the drive shafts and the rollers for various purposes, such as to swap out the rollers for different applications. The more efficiently this task is able to be done, the less downtime is required for the task and more desirable and economical is the functionality of the machine for the operator. This is where the nature of the coupling  10  is particularly paramount. 
     Referring now to  FIGS. 1-15 , the coupling assembly  10  is mainly comprised of a driving hub  12 , a driven hub  14 , a key or power transmitting member  16 , ball bearings  18 , a locking sleeve  20 , a spring  22  and a retaining ring  24 . 
     The driven hub  14 , as best shown in  FIGS. 7-9 , is formed of a suitable material capable of handling the stress of the power transmission, such as a metal or hard plastic, and in the illustrated embodiment is formed to be generally cylindrical in shape, defining a central passage  600 . The driven hub  14  is affixed to the journal (not shown) of the roller in any suitable manner, such as by using suitable means (not shown) such as mechanical fasteners or welds. 
     The driving hub  12 , as best shown in  FIGS. 2-5 , is also formed of a suitable material capable of handling the stress of the power transmission, such as a metal or hard plastic, and in the illustrated embodiment is also formed to be generally cylindrical in shape, defining a central passage  300 . The exterior surface of the drive hub  12  includes a large diameter section  33 , an intermediate diameter section  34  and a small diameter section  35 . The drive hub  12  is connected to the drive shaft in any suitable manner, such as by using mechanical fasteners (not shown) engaged with the drive shaft and inserted into blind bores  25  in the driving hub  12 . The driven hub  14  is formed to have a diameter slightly less than that of the driving hub  12 , such that the driven hub  14  can be inserted within the central passage  300  of the drive hub  12 . 
     The key  16 , as best shown in  FIGS. 13-14 , is formed of a suitable material capable of handling the stress of the power transmission, such as a metal or hard plastic, and can be formed to have any suitable shape, which in the illustrated embodiment is generally rectangular in cross-section. 
     To operably align and connect the drive or driving hub  12  to the driven hub  14  and enable power transmission therebetween, the drive hub  12  includes an aligning structure, which in the illustrated embodiment is formed of a pair of inwardly extending slots  30  formed in the end of the drive hub  12  formed by the large diameter section  33 . The slots  30  have a shape complementary to that of the key  16 , which is attached to the driving hub  12  by seating the key  16  securely within the opposed slots  30  such that the key  16  extends between the opposed slots  30  formed in the drive hub  12  across the central passage  300 . The key  16  is retained in this position in any suitable manner, and in the illustrated embodiment this is accomplished by using fasteners  29  that are inserted through the bores  27  in the key  16  and engaged within corresponding aligned apertures  28  in the drive hub  12 . 
     When the driven hub  14  is inserted into the driving hub  12 , the key  16  is positioned within corresponding notches  32  in the driven hub  14 , thereby mechanically engaging the driven hub  14  to the driving hub  12  and allowing transmittal of power through the assembly  10  from the rotating driveline to the roller. In one embodiment of the driven hub  14 , the hub  14  includes two pairs of notches  32  offset by ninety degrees (90°) to enable the driven hub  14  to engage the drive hub  12  in two separate positions, thereby increasing the ease of connecting the hubs  12 , 14  in conjunction with a tapered or curved surface  31  on the driven hub  14 . 
     Looking now at  FIGS. 16-23  a second embodiment of the assembly  10 ′ is illustrated in which the alignment structure forming the connection between the key  16  and the driven hub  14  is altered. In this embodiment, as best shown in  FIGS. 21-23 , the key  16  includes a pair of pins  400  extending outwardly from the key  16  into the central passage of the drive hub  12 . 
     The pins  400  are alignable with opposed pairs of axially extending apertures  500  formed in the driven hub  14  in place of the notches  32 . As best shown in  FIGS. 16-20 , when the driven hub  14  is inserted within the passage  300  of the drive hub  12 , the pins  400  are received in aligned pairs of the apertures  500  to mechanically engage the hubs  12 ,  14 . Further, as shown in the illustrated embodiment, due to the position of two separate arrays  502  of apertures  500  on opposed sides of the driven hub  14 , there are multiple angular positions in which the pins  400  can be aligned with a pair of apertures  500 . While the number and size of the apertures  500  and the corresponding size of the pins  400  can be varied as desired to provide the desired number of angular configurations in which the pins  400  can be engaged within the apertures  500 , in a preferred embodiment the apertures  500  are positioned to provide engaged configurations between the hubs  12 ,  14  at approximately twenty-six degree (26°) increments. 
     Looking now at  FIGS. 1-6  and  10 - 12 , the sleeve  20  is positioned around the driving hub  12  over intermediate and small diameter sections  34 ,  35  formed on the exterior of the hub  12 . The sleeve  20  has an outer diameter approximately equal to that of the large diameter section  33  of the drive hub  12  to reduce the overall profile of the coupling  10 . In the illustrated embodiment, the generally smooth exterior surfaces of the sleeve  20  and the drive hub  12  also eliminates a number of projecting surfaces present on prior art couplings, and greatly reduces the number of exposed surfaces on the coupling  10  that can potentially snag or otherwise become engaged with loose clothing or other items, which consequently reduces the chance of injury when the machine utilizing the coupling  10  is in operation. 
     The interior of the sleeve  20  includes a circumferential recess or cavity  100  that is disposed in alignment with the small and intermediate diameter sections  34 ,  35  of the drive hub  12 . The cavity  100  is bounded by a first radially inwardly extending tab  102  at one end and a second radially inwardly extending tab  104  located opposite the first tab  102  that is joined to the cavity by a sloped surface  106 . The first tab  102  has an inner diameter slightly larger than that of the small diameter section  35  of the drive hub  12 , and the second tab  104  has a diameter slightly larger than that of the intermediate section  34 . The inner diameter of the second tab  104  is less than the diameter of the large diameter section  33  of the hub  12  such that the large diameter section  33  engages the second tab  104  and retains the sleeve  102  on the hub  12 . 
     Looking now at  FIG. 1 , opposite the large diameter section  35 , the sleeve  20  is additionally retained on the hub  12  by a stop or retaining ring  24  engaged around the hub  12 , such as in a peripheral notch  36  disposed in the small diameter section  35  generally opposite the slots  30 . The ring  24 , by engaging the first tab  102 , keeps the sleeve  20  on the hub  12  while enabling the sleeve  20  to slide with respect to the hub  12 . 
     The spring  22  is disposed around the small diameter section  35  of the hub  12  within the cavity  100 , such that the spring  22  is held in compressive engagement between the intermediate diameter section  34  of the hub  12  and the first tab  102  of the sleeve  20 . Thus, the spring  22  continuously urges the sleeve  20  towards the ring  24  to keep the cavity  100  over the reduced diameter section  34 . 
     In the locked position shown in  FIG. 1 , the second tab  104  of the sleeve  20  covers a number of bores  38  formed within the intermediate diameter portion  34  of the hub  12  and in each of which is positioned a ball bearing  18 . The bearing  18  is free to move within each of the bores  38  the on the driving hub  12 . The bearings  18  protrude into the central passage  300  of the hub  12  when engaged by the second tab  104  of the sleeve  20 . In this position, when the driven hub  14  is inserted within the drive hub  12 , the bearings  18  extend into a peripheral groove  200  formed in the exterior of the driven hub  14  to hold the driven hub  14  in engagement with the drive hub  12 . 
     The coupling  10  meets the needs of easily repeated quick connecting and quick disconnecting by the operator. Hereby, the coupling  10  allows initial engagement of the hubs  12 ,  14  without the need to perfectly align torque transmitting members. Once the hubs  12 ,  14  begin engagement, the drive shaft and attached driving hub  12  can be supported by the driven hub  14 , so the operator does not need to be concerned with supporting its weight and bulk while simultaneously attempting to engage torque transmitting members. At that point, the operator can then focus on completing the engagement of coupling hubs  12 ,  14  by mating the torque transmitting members, which is aided by transitioned engagement surfaces on the exterior of the driven hub  14  and the interior of the driving hub  12 . 
     In operation, common to both the connection and disconnection of the coupling  10 , the operator draws the coupling sleeve  20  linearly along the coupling axis, thereby causing the first tab  102  to compress the spring  22  and moving the cavity  100  over the bores  38 , the centerlines of which are perpendicular to the coupling assembly axis. When the sleeve  20  is drawn along the drive hub  12 , the position of the cavity  100  over the bores  38  allows the ball bearings  18  the freedom to move through the cylindrical bores  38  away from the inside diameter of the driving hub  12  to protrude into the cavity  100  of the sleeve  20 , such that the bearings  18  are not located at all within the passage  300  of the drive hub  12 . When given this degree of freedom, the ball bearings  38  offer no resistance to the insertion or removal of the driven coupling hub  14  in relation to the driving hub  12 . 
     As the operator begins to release the sleeve  20 , the spring  22  forces the sleeve  20  back linearly toward its resting, or locked position. As the sleeve  20  moves, the transition of diameters on the inside surface of the sleeve  20  along the sloped surface  106  between the cavity  100  and the second tab  104  allows the sleeve  20  to contact the ball bearings  18 , simultaneously driving them back through their cylindrical holes  38  toward and into the passage  300  of the driving hub  12 . 
     The locked condition of the fully connected coupling hubs  12 ,  14  is maintained by the relationship between the extreme inner diameter of the second tab  104  on the sleeve  20  and the position of the cylindrical holes  38  in the driving hub  12 . This relationship creates a captured state of the ball bearings  18  to a predetermined protrusion of the ball bearings  18  into the central passage  300  of the driving hub  12 . Only when the driven hub  14  is fully connected with the driving hub  12  can the operator completely release the sleeve  20  which forces the ball bearings  18  evenly into the radial groove  200  of the driven hub  14 , thereby holding the driven hub  14  in correlation to the driving hub  12 . This is then the fully connected and locked condition of the coupling assembly  10  at which point it is ready to perform work. 
     Conversely, to relieve the coupling  10  from its working condition, when the driveline is static, the operator is to draw or compress the sleeve  20 , thereby allowing each ball bearing  18  its freedom of movement, as the operator, while holding the sleeve  20  in its drawn position, pulls the entire driving hub  12  and drive shaft linearly off the driven hub  14 . As this disconnecting movement occurs, the contour of the radial groove  200  of the driven hub  14  automatically forces the ball bearings  18  through their cylindrical bores  38  and into the sleeve cavity  100 , which allows for the complete removal of the driving hub  12  and drive shaft. Notable to this application is that the drive shaft is collapsible. This is then the fully disconnected condition of the coupling assembly  10 . 
     Aside from the simple function of the sleeve  20  under spring force, there is no need for a dedicated individual hub-locking assembly in the coupling  10 . This thereby eliminates the need for many more component parts, associated costs, assembly and maintenance thereof. In addition, since the coupling  10  works on a horizontal axis, the forces that may act upon the coupling assembly  10 , and specifically its locking feature, are known and limited. This therefore compliments the practical simplicity of the sleeve-locking feature. 
     As an additional beneficial feature of the construction of the assembly  10 , the operator has the advantage of utilizing the movement and force of hands and arms in the same linear direction to simultaneously and comfortably compress the sleeve  20  and disconnect the driving hub  12  and drive shaft from the driven hub  14 . 
     While the concepts of the present disclosure will be illustrated and described in detail in the drawings and description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only the illustrative embodiments are shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. There are a plurality of advantages that may be inferred from the present disclosure arising from the various features of the apparatus, systems, and methods described herein. It will be noted that alternative embodiments of each of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the inferred advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an apparatus, system, and method that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the disclosure as defined by the appended claims.