Abstract:
The present invention provides a coupler for rotationally and/or axially securing two shafts together while permitting rapid angular adjustment between the shafts. The coupler includes a first component mountable to a first section of the paddle and a second component mountable to a second section of the paddle. The first component includes a receptacle, and the second component includes a protrusion operable to extend into the receptacle to position the first component relative to the second component and to prevent the first component from turning relative to the second component. To turn and reposition one of the components relative to the other component, the second component is axially movable relative to the first component. The coupler may also include a retainer to prevent the first component from inadvertently being repositioned relative to the second component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from commonly owned U.S. Provisional Patent Application No. 60/399,932, filed Jul. 30, 2002, titled Ferrule For Connecting Portions Of A Paddle Together And For Adjusting The Feather Of A Double-Bladed Paddle, presently pending, which is hereby incorporated by reference in its entirety. 

   BACKGROUND 
   When kayaking on a river, lake or ocean, many kayakers propel themselves with a double-bladed paddle. Due to the rotation of one&#39;s torso combined with raised hands during a forward stroke it is necessary to feather the kayak paddle. In addition kayakers often encounter windy conditions when kayaking—especially on a large lake or an ocean, a kayaker&#39;s paddle is often feathered to reduce the wind drag of the paddle blade not in the water. Feather is the angular relationship of the plane of one paddle blade relative to the plane of the other paddle blade and is often expressed as the angle between the planes. Feathering a paddle alleviates potential stress on the wrists, which may be significant over a long excursion. Because kayakers use a variety of paddling styles, a paddle whose feather may be adjusted allows a kayaker to modify his/her paddle to match his/her style and conditions. 
   There are many conventional coupling arrangements available that allow one to adjust the feather of a paddle. An example of a conventional coupling arrangement is shown in FIG.  1  and includes a collet  10  to frictionally couple shaft sections of a paddle with each other. As shown in  FIG. 1 , the collet  10  includes a collar  12  mounted to a shaft  14 , and a compression nut  16  that slides along the shaft  18 . When the collar  12  is engaged with the compression nut  16 , the shaft  18  is frictionally prevented from moving relative to the shaft  14  due to constriction of the collar  12  around the shaft  18 . 
   Unfortunately, the collet  10  has some problems. One of the problems is that the collet  10  frequently does not securely couple the shafts  14  and  18  with each other. Because the collet  10  frictionally couples the shaft  18  with the shaft  14 , twisting and/or pulling the shaft  14  relative to the shaft  18  can cause a loss of desired feather in the paddle and can cause the shafts to separate. To more securely couple the shafts  14  and  18  with each other, one may increase the constricting force on the collar  12  by threading the compression nut  16  further along the collar  12  with much force. But this induces undesired stress in the collet  10  and the shaft  18 , which typically causes the collet  10  to wear out prematurely. Furthermore, the compression nut  16  may become stuck with the collar  12  and make uncoupling the shafts  14  and  18  to adjust the feather of a paddle difficult. 
   Another example of a conventional coupling arrangement is a button (not shown) that protrudes from a first shaft of one paddle section into a hole (not shown) in a second shaft of another paddle section. To provide different indexed positions, and thus different feather angles, more than one hole is located about the circumference in the second shaft. The button typically travels in a radial direction or perpendicular to the longitudinal axis of each shaft and is biased away from each shaft&#39;s longitudinal axis by a spring; the hole is typically sized to closely receive the button. Once inserted into the hole, the button prevents the shafts from rotating relative to each other and may further prevent the paddle sections from being pulled apart as one uses the paddle. 
   Unfortunately, this type of coupling arrangement also has some problems. The number of different indexed positions is limited to the number of holes the shaft can include without causing the shaft to buckle or permanently deform under the strain of use. In addition, the holes in the shaft or the button often deform from the force imposed by the respective button, or shaft over prolonged use. This causes the feather of the paddle associated with a specific indexed position to change over time and introduces play or undesirable movement between the paddle sections when the sections are connected to each other. This undesirable play in turn hastens further deformation of the hole and the eventual permanent deformation or failure of the paddle. 
   SUMMARY 
   The present invention provides a coupler for rotationally and/or axially securing two shafts together while permitting rapid angular adjustment between the shafts. For example, in a double-bladed paddle the coupler releasably couples a shaft of a first section of a paddle that includes a paddle blade with a shaft of a second section that also includes a paddle blade. In such a double-bladed paddle, the coupler allows one to change the relative angular position of the two shafts among many different and consistent positions and then more securely couples the sections together in each position to adjust and retain a desired feather of the paddle. 
   The coupler includes a first component mountable to a first section of the paddle and a second component mountable to a second section of the paddle. The first component includes a receptacle, and the second component includes a protrusion operable to extend into the receptacle to position the first component relative to the second component and to prevent the first component from turning relative to the second component. To turn and reposition one of the components relative to the other component, the second component is movable relative to the first component along the paddle axis. 
   In one embodiment, the second component includes 24 protrusions each including a rectangular key, and the first component includes 24 receptacles each including a keyway sized to receive each key. In such an embodiment, each key and corresponding keyway prevent the first component from turning relative to the second component in each angular position of the first component. Thus, the coupler spreads the bearing force generated in the coupler over many keys and keyways. Consequently, the coupler may provide more angular positions for the first component relative to the second component and thus greater feather adjustment. Furthermore, over prolonged use, the coupler may couple the sections of a paddle at the same or substantially the same designed angular position and with minimal play between the sections. Thus, the coupler may provide more consistent paddle feathers over prolonged use. 
   In another embodiment, the coupler may also include a retainer to prevent the first component from inadvertently being repositioned relative to the second component. The retainer may be mounted to the first component and may include a hook that can receive a lip of the second component to releasably lock the first component with the second component by preventing the movement of the first component relative to the second component along the paddle axis. The retainer may also include a spring to bias the hook toward the lip when the protrusion of the second component extends into the receptacle of the first component. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a cross-sectional view of a conventional coupler. 
       FIG. 2  is a perspective view of a double-bladed paddle that incorporates a coupler, according to an embodiment of the invention. 
       FIG. 3  is an exploded, perspective view of the coupler in  FIG. 2  according to an embodiment of the invention. 
       FIG. 4  is a cross-sectional view of the coupler in  FIG. 3  showing a first component of the coupler locked in an angular position relative to a second component of the coupler. 
       FIG. 5  is an exploded, perspective view of a coupler according to another embodiment of the invention. 
       FIG. 6  is an exploded, perspective view of a coupler according to yet another embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   The following discussion is presented to enable one skilled in the art to make and use the invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention as defined by the appended claims. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 
     FIG. 2  is a perspective view of a paddle  30  that incorporates a coupler  32 , according to an embodiment of the invention. The coupler  32  (shown and discussed in greater detail in conjunction with  FIGS. 3-6 ) angularly positions the sections  34  and  36  of the paddle  30  relative to each other about a paddle axis  38 , and releasably couples the sections  34  and  36  with each other in an established angular position. The coupler  32  may also include a retainer  39  (shown and discussed in greater detail in conjunction with  FIGS. 3 and 4 ) to lock the sections  34  and  36  in the established, relative angular positions. As shown, the paddle  30  is a double-bladed paddle that includes a first section  34  having a blade  40  and a second section  36  having a blade  42 . By angularly positioning the sections  34  and  36  relative to each other about the paddle axis  38 , one may adjust the paddle&#39;s feather as desired, for example to match currently existing wind conditions. 
   The coupler  32  may angularly position the sections  34  and  36  relative to each other about the paddle axis  38  among different angular positions as desired. The different angular positions may be equally, angularly spaced through 360° or any portion of 360°, such as 90°, 180° or 135°. For example, in one embodiment, the coupler  32  may releasably couple the sections  34  and  36  together at 24 different angular positions about the paddle axis  38  that are angularly spaced 15° or substantially 15° between adjacent angular positions. This may be desirable to provide a broad range of feather angles with moderate angular spacing between adjacent feather angles. In another embodiment, the coupler  32  may releasably couple the sections  34  and  36  together at 24 different angular positions that are spaced 5° or substantially 5° between adjacent angular positions. In such an embodiment, the feather of the paddle  30  may range from 0° to 120° and may be desirable to provide a narrower range of feather angles with less angular spacing between adjacent feather angles. In still another embodiment, the coupler  32  may releasably couple the sections  34  and  36  together at 10 different angular positions that are unequally spaced between adjacent angular positions. This may be desirable to provide small angular spacing between adjacent angular positions within a popular range of feather angles and larger angular spacing between adjacent angular positions within a less popular range of feather angles. 
   With the coupler  32 , one may quickly and easily change the angular position of the sections  34  and  36  relative to each other about the paddle axis  38  to change the feather of the paddle  30 . In one embodiment, one first unlocks the coupler  32  to uncouple the sections  34  and  36  from each other by pushing the retainer  39  toward the paddle axis  38 . Next, one moves the section  36  in a direction  44  away from the section  34  along the paddle axis  38  to uncouple the sections  34  and  36 . Next, one turns the section  36  relative to the section  34  about the paddle axis  38  to reposition the section  36  relative to the section  34  at a different angular position. Next, one moves the section  36  in a direction  46  toward the section  34  along the paddle axis  38  to couple the sections  34  and  36  together and to lock the sections  34  and  36  in the new established angular position. 
   Other embodiments of the paddle  30  that incorporate the coupler  32  are contemplated. For example, the paddle  30  may be a single bladed paddle with one of the sections  34  and  36  having a handle instead of another blade. In addition, unlocking the coupler  32  may include moving the retainer  39  along the paddle axis  38  and/or turning the retainer  39  about the paddle axis  38 . Also, uncoupling the sections  34  and  36  may include moving the section  36  toward the section  34  along the paddle axis  38 , and coupling the section  36  with the section  34  may include moving the section  36  away from the section  34  along the paddle axis  38 . 
     FIG. 3  is an exploded, perspective view of the coupler  32  in  FIG. 2  according to an embodiment of the invention. The coupler  32  releasably couples the sections  34  and  36  ( FIG. 2 ) together more securely in different angular positions about the paddles axis  38  (FIG.  2 ). Furthermore, the coupler  32  maintains the designed feather angle among different angular positions over prolonged use. 
   The coupler  32  includes a first component  50  mountable to the section  34  of the paddle  30 , and a second component  52  mountable to the section  36  of the paddle  30 . The first component  50  includes a receptacle  54 , and the second component  52  includes a protrusion  56  that extends into the receptacle  54  when the first component  50  is coupled with the second component  52 . By extending into the receptacle  54 , the protrusion  56  and receptacle  54  angularly position the first component  50  relative to the second component  52  and prevent the first component  50  from turning relative to the second component  52 . 
   Still referring to  FIG. 3 , the first component  50  may include one or more receptacles  54  and the second component  52  may include one or more protrusions  56 . Furthermore, the protrusions  56  and the receptacles  54  may have any desired form. For example in one embodiment, the second component  52  may include a perimeter  58  from which 24 protrusions  56  extend, and the first component  50  may include 24 receptacles  54 . Each protrusion  56  may include a rectangular key  60 , and each receptacle  54  may include a rectangular keyway  62  sized to receive each key  60 . When each key  60  extends into a respective keyway  62 , the first component  50  is angularly positioned relative to the second component in one of 24 angular positions and is prevented from turning relative to the second component  52  by the 24 keys  60  and keyways  62 . Thus, the force required to keep the first component  54  in an angular position relative to the second component may be distributed throughout the perimeter  58 . Furthermore, holding an angular position of the first component  50  relative to the second component does not require friction between the two components  50  and  52 . Consequently, the angular position of the first component  50  relative to the second component  52  is less likely to inadvertently change when subjected to severe loads, and the different angular positions of the first component  50  relative to the second component  52  may remain consistent over prolonged use. 
   Other embodiments are contemplated. For example, the first component  50  may include the protrusion  56  and the second component  52  may include the receptacle  54 . Also, as shown and discussed in conjunction with  FIG. 5 , the second component  52  may include one protrusion  56  and the first component  50  may include two or more receptacles  54 . Or, as shown and discussed in conjunction with  FIG. 6 , the second component  52  may include two or more protrusions  56 , and the first component  50  may include one receptacle  54 . Furthermore, the protrusion  56  and the receptacle  54  may include forms other than the rectangular key  60  and keyway  62 , respectively, such as a trapezoidal key and keyway. 
   Still referring to  FIG. 3 , the coupler  32  may include a retainer  39  to lock the angular position of the first component  50  relative to the second component  52  when the first and second components  50  and  52  are coupled with each other. In one embodiment, the retainer  39  may include a body  64 , a hook  66  that extends from the body  64  and a spring  68  to bias the retainer  39  toward a lock position (shown and discussed in greater detail in conjunction with FIG.  4 ). The body  64  may be disposed in the hole  70  of the first component  50  and allowed to move in the direction  72  within the hole  70  to locate the retainer  39  in the locked or unlocked position. The spring  68  may be compressed between the body  64  and the bottom  74  of the hole  70  and may urge the retainer  39  toward the lock position. When the retainer  39  locks the first component  50  with the second component  52 , the hook  66  receives a portion of the lip  76  of the first component  50  and prevents the lip  76  from moving in the direction  78  relative to the hook  66 , and the wall  80  of the hole  70  prevents the body  64  from moving in the direction  78  relative to the first component  50 . Thus, the retainer  39  locks the angular position of the first component  50  relative to the second component  52  by preventing the first component  50  from moving in the direction  78  relative to the second component  52 . 
   Other embodiments are contemplated. For example, the spring  68  may be a solid plug of urethane that resists compression. In addition, the second component  52  may include a retainer  39  that may be a pin having a longitudinal axis that extends away from the perimeter  58  and that may be located at the end of a cantilevered leaf spring of the second component  52 . To lock the angular position of the first component  50  relative to the second component  52 , the leaf spring may insert the pin into a hole in the corresponding component. Furthermore, the first component  50  may include the pin and cantilevered leaf spring and the second component  52  may include the hole. 
   Still referring to  FIG. 3 , the coupler  32  may be made of any desirable material capable of withstanding the environment the coupler will function in, such as salt water or fresh water. For example, in one embodiment, the first and second components  50  and  52  may be made of polycarbonate; the body  64  and hook  66  may also be made of polycarbonate; and the spring  68  may be made of AISI Type 316 stainless steel. 
     FIG. 4  is a cross-sectional view of the coupler in  FIG. 3  showing the first component  50  of the coupler  32  locked in an angular position relative to the second component  52  of the coupler  32 .  FIG. 4  also shows the first component  50  of the coupler  32  mounted to the section  34  of the paddle  30  (FIG.  2 ), and the second component  52  mounted to the section  36 . 
   As shown in  FIG. 4 , the retainer  39  locks the angular position of the first component  50  relative to the second component  52  by preventing the first component  50  from moving away from the second component  52  along the paddle axis  38 . Consequently, the one or more protrusions  56  ( FIG. 3 ) of the second component  52  are kept in the one or more respective receptacles  54  ( FIG. 3 ) of the first component  50 . In one embodiment, when the hook  66  is in the locked position, the hook  66  may hold a portion of the lip  76  to prevent the lip  76  from moving in a direction along the paddle axis  38 . The spring  68  may urge the hook  66  toward the lip  76  to prevent the hook  66  from inadvertently moving away from the lip  76 , and thus, inadvertently releasing the hook&#39;s hold on the portion of the lip  76 . When the hook  66  is in the unlocked position, the hook  66  may be located away from the portion of the lip  76  to release the hook&#39;s hold on the lip&#39;s portion and allow the lip  76 , and thus, the second component  52 , to move away from the first component  50  along the paddle axis  38 . To unlock the angular position of the first component  50  relative to the second component  52 , one may exert pressure on the top  82  of the retainer&#39;s body  64  to move the hook  66  away from the portion of the lip  76 . When the pressure on the top  82  is removed, the spring may urge the hook  66  back toward the locked position, where the hook  66  may again hold a portion of the lip  76 , if a portion of the lip  76  is so located. 
   Still referring to  FIG. 4 , the coupler  32  may be mounted to the sections  34  and  36  of the paddle  30  using any desired technique capable of withstanding the loads and environment the paddle  30  may experience during use. For example, in one embodiment, the second component  52  of the coupler  30  may be mounted to a second section  36  of the paddle  30  with any desired adhesive at the interface  84 . The first component  50  of the coupler  32  may be releasably mounted to a first section  36  with a pin  86  that may extend through a hole  88  in the first component  50  and two holes (not shown) in the body  90  of the section  34 . To access the retainer  39  to unlock the angular position of the first component  50  relative to the second component  52 , the top  82  of the retainer&#39;s body  64  may extend through a hole  92  in the paddles section&#39;s body  90 . 
     FIG. 5  is an exploded, perspective view of a coupler  100  according to another embodiment of the invention. The coupler  100  is similar to the coupler  32  in  FIGS. 3 and 4  except the second component  102  includes one protrusion  104 , and the first component  106  includes at least two receptacles  108 . The coupler  100  may be desirable to withstand frequent, prolonged adjustments of the angular position of the first component  106  relative to the second component  102  when the angular spacing between adjacent angular positions may be moderate or large. 
     FIG. 6  is an exploded, perspective view of a coupler  110  according to yet another embodiment of the invention. The coupler  110  is similar to the coupler  32  in  FIGS. 3 and 4  except the second component  112  includes at least two protrusions  114 , and the first component  116  includes one receptacle  118 . The coupler  110 , like the coupler  100  of  FIG. 5 , may be desirable to withstand frequent, prolonged adjustments of the angular position of the first component  116  relative to the second component  112  when the angular spacing between adjacent angular positions may be moderate or large.