Abstract:
A fence tensioner has a frame which may be rigid or articulated. The tensioner carries on each end thereof a rotatable cylindrical member which is provided with an axial slot to accommodate the profile of a section of fence. The cylindrical member is provided a ratchet and a pawl to lock the cylinder against loosening rotation. The pawl has a square end to lock the ratchet and eliminate any backlash and any slack in the fence members. The frame of the device is articulated so that each end of the device may accommodate the angle of the fence relative to the post. The vinyl fencing fits into the tensioner and locks itself therein as the cylinder rotates.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The present invention relates, in general, to a tensioning device for flexible members such as polymer fencing. More particularly, the invention relates to a tensioning device that may be affixed to any standard fence post and may be used to apply tension to any flexible member and, more specifically, a polymer fencing member having a plurality of steel wires encapsulated therein.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known in the art to utilize fencing to confine livestock in a defined area. Various types of fencing are available including wood, wire, barbed wire, chain link, and polymer fencing. In comparison to other types of fencing, polymer fencing provides significant advantages in terms of cost, aesthetics, visibility, and reduced risk of harm to any confined animals.  
         [0003]     Numerous prior art polymer fencing systems are known. For example, U.S. Pat. No. 4,374,798 to Mercer discloses a plastic mesh structure suitable for use as fencing. Another particularly preferred polymer fencing system is disclosed in U.S. Pat. No. 4,465,263 to Robbins, Jr. (now U.S. Pat. No. Re. 32,707), comprising an elongated vinyl plastic webbing having parallel strands of high tensile wire encased therein. This latter fencing is designed to imitate wood fencing in terms of aesthetics while advantageously reducing the cost of purchase and maintenance associated with wood fencing. Both U.S. Pat. Nos. 4,374,798 and 4,465,263 are incorporated herein by reference.  
         [0004]     In order for the fencing system to be effective regardless of the type of polymer fencing utilized, it must be placed under sufficient tension to prevent sagging of individual fencing members or strands. Standard tensioning devices for wire or barbed wire-type fencing are highly effective for their intended purpose. However, they suffer from the limitation that only a single strand of wire can be tensioned at a time. Accordingly, single wire prior art tensioning devices are unsuited for tensioning polymer fencing systems which either have a plurality of wires or within which individual wires cannot be accessed. This prior art tensioning device is particularly unsuited for applying tension to fencing systems that must be tensioned concurrently along two parallel edges.  
         [0005]     Prior art systems for tensioning polymer fencing are known. For example, the tensioning system disclosed in U.S. Pat. No. 5,409,196 to Specht includes a mounting batten designed to be fastened to a structural support post. The mounting batten forces the polymer fencing against a correspondingly formed elastic extrusion or metal form channel batten, thereby placing the fencing under tension. Similarly, U.S. Pat. No. 5,660,377 to Specht discloses a tensioner bar designed to be fastened to a structural support post containing a correspondingly shaped recess. The tensioner bar forces the polymer fencing into the correspondingly shaped recess, thereby placing the fencing under tension. These systems are generally effective for certain types of polymer fencing. However, they suffer from the disadvantages of requiring either a specially formed structural support post or multiple components, such as mounting battens and correspondingly shaped channel battens. Accordingly, there is need in the art for a tensioning system for a polymer fence member which can be used with a standard, unmodified support structure such as a fence post.  
       SUMMARY OF THE INVENTION  
       [0006]     The tensioning device of the present invention is constructed to be used in conjunction with a standard support structure such as an ordinary fence post. The device of this invention is particularly suited for tensioning flexible members, such as the polymer fencing, having substantially parallel edges as well as a substantially flat web portion between its edges, as in disclosed in U.S. Pat. No. 4,465,263 to Robbins (now U.S. Pat. No. Re. 32,707) and U.S. Pat. No. 4,533,120. However, it should be appreciated that the device of this invention is suitable for tensioning any flexible member.  
         [0007]     The tensioning device of the present invention includes a body constructed of a material of sufficient strength to provide the force required to tension a flexible member such as steel, iron, aluminum, plastics, rubberized compounds, composites, or suitable polymers. This device includes at least one rotary tensioner. Means for affixing the device to any standard support structure, such as an ordinary fence post, is also provided. In one embodiment of the invention, the body of the tensioning device comprises a single unitary structure. Also, in an especially preferred embodiment of the present invention, the body of the tensioning device is articulated such that the tensioner may be set at a separate angle relative to the vertical axis of the fence post.  
         [0008]     In a preferred embodiment of the present invention, the rotary tensioner comprises a rotary member incorporating a slot of suitable length, width, and depth to allow insertion prior to rotation of an end of the particular flexible member into the cylindrical portion of the tensioner. The tensioning device further includes a locking mechanism for locking the rotary member to prevent it from rotating in an undesirable direction, i.e., in such a manner as to lose tension on the flexible member.  
         [0009]     In one aspect of this invention, the tensioning device of this invention incorporates a single tensioner. In yet another aspect, the tensioning device of this invention incorporates dual tensioners for applying tension to the adjacent ends of a pair of flexible members.  
         [0010]     Additional advantages and other novel features of the invention will be set forth in part in the description that follows and will become apparent to those skilled in the art either upon examination of the following or may be learned with the practice of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a top view of the tensioner with two tensioners.  
         [0012]      FIG. 2  is a bottom view of the tensioner with two tensioners.  
         [0013]      FIG. 3  is a front view of the tensioner with two tensioners..  
         [0014]      FIG. 4  is a bottom view of an embodiment of the device having only a single tensioner.  
         [0015]      FIG. 5  is a front view of an embodiment of the device which is articulated to accommodate an uneven ground surface.  
         [0016]      FIG. 6  is a front view of the articulated embodiment with a level shape. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Referring to  FIGS. 1 and 2 , the tensioning device  10  of this invention comprises a top plate  12  and a bottom plate  14 . Top plate  12  and bottom plate  14  are separated by a substantially rectangular spacing plate  16 . Shown in  FIG. 3 , spacing plate  16  contains an aperture  18  for receiving a fastener  23  for fastening the device  10  to a support structure  52 , such as a fence post  52  or a retaining wall. Aperture  18  is used to fasten the tensioning device  10  to a support or fence post  52  and may be an elongated slot  18  allowing adjustment of the tensioning device  10  along a horizontal plane. However, depending upon the desired direction of adjustment it should be appreciated that an aperture of any suitable shape or size may be incorporated into the spacing plate  16 .  
         [0018]     In a preferred embodiment as shown in  FIG. 2 , the tensioning device  10  is substantially “C-shaped.” Top plate  12  comprises a narrow central portion  20  which widens at ends  22  and  24 . Bottom plate  14  is similarly shaped, comprising a narrow central portion  20 ′ and widening at ends  22 ′ and  24 ′. Ends  22 ,  22 ′,  24 , and  24 ′ contain substantially aligned apertures  42  therethrough for rotatably receiving and supporting a rotary tensioner  26 , as best seen in  FIG. 3 .  
         [0019]     As those of skill in the art will appreciate, this design allows the interior of tensioning device  10  to engage or be positioned around a support structure such as a fence post  52 . In this embodiment, the interior of the tensioning device  10  may be placed in close proximity to a support structure  52 , such as a standard fence post, and affixed thereto by any suitable fastener, such as a bolt  23 , lag screw  23 , or other fastener of choice. However, it should be appreciated that many other configurations for the device  10  are possible depending upon the structure to which the device is to be affixed. For example, a substantially flat interior portion would be preferred if the tensioning device  10  was to be affixed to a substantially flat support structure, such as a wall. A substantially rectangular interior portion would be desirable if the device was to be affixed to a square fence post.  
         [0020]     The tensioning device  10  includes at least one rotary tensioner  26 . In a presently preferred embodiment of this invention best seen in  FIGS. 1, 2  and  3 , the device  10  includes a pair of tensioners  26 , rotatably inserted into each opposing end  22 ,  22 ′,  24 ,  24 ′ of the tensioning device  10 . Each tensioner  26  comprises a rotary member  27 , rotatably inserted through the apertures  42  in top plate  12  and bottom plate  14 . As seen in  FIG. 3 , tensioner  26  comprises a retainer flange  28  at one end of a substantially cylindrical body portion  27  and a locking mechanism  32  or ratchet  32 , secured thereto at a second end, for locking the rotary tensioner  26  in place. The retainer or flange  28  may be of any shape suitable to prevent withdrawal of the rotary tensioner  26  from aperture  42  in top plate  12 . Retainer or flange  28  includes an opening  44  formed in a shape suitable for insertion of a lever (not shown) with an end adapted to the shape of opening  44 . By use of the lever, the rotary member  27  may be rotated to wind and thus to achieve tensioning of a flexible member  50  inserted therein.  
         [0021]     Along its exterior cylindrical portion  27  includes slot  34  of an appropriate size and shape for insertion of a flexible member therein for tensioning. As will be appreciated, cylindrical portion  27  may be hollow or solid depending on the particular strength and weight requirements for the flexible member undergoing tensioning. Of course, the particular length, width, depth, and shape of slot  34  is dependent upon the size and shape of the flexible member to be inserted therein. The shape of slot  34  in the present invention extends the entire length of the exposed cylinder  27  and extends radially into the rotary tensioner cylinder  26 . The shape of the slot  34  includes an enlarged width  31  at the ends and the midpoint of the slot  34  to accommodate a portion of a flexible member  50  or fencing material  50  which encloses the longitudinal wires therein.  
         [0022]     In a preferred embodiment of this invention, the locking mechanism comprises a ratchet wheel  32  and pawl  38  arrangement. As best seen in  FIG. 4 , the fence tensioner  10  includes a toothed ratchet wheel  32  secured for rotation with rotary member  27  and a substantially rectangular pawl  38  engageable at its proximal end  39  with the teeth  33  of the ratchet wheel  36 . The need for these specific shapes will be discussed in greater detail below. Advantageously, ratchet wheel  32  also retains the rotary member  27  to prevent removal from the apertures  42 . Pawl  38  is maintained in engagement with ratchet wheel  32  by engagement of the square proximal end  39  of pawl  38 . The ratchet wheel  32  tooth  33  profile is neutral insofar as the lateral forces on the pawl  38  and tends not to latch or unlatch the pawl  38 .  
         [0023]     In one particular preferred embodiment, the tensioning device  10  of this invention includes a rotary tensioner  26  at each end of the device  10 . In this embodiment, as best seen in  FIGS. 2 and 3 , spring  40  is connected to each of the pawls  38  at their distal end  30 , thereby simultaneously urging the proximal ends  39  of pawls  38  into engagement with a mating tooth  33  on ratchet wheel  32 . As it will be appreciated, in this manner it is possible to simultaneously apply tension to two flexible members with the device of this invention; each flexible member extends therefrom in opposing directions to form the fence. Further, because the dual means for tensioning a flexible member operate independently of one another, yet each of pawl members  38  are biased by spring  40 , it is possible to apply tension to one flexible member  50  without undesirable loss of tension to a second flexible member  50 .  
         [0024]     It should be appreciated that the tensioning device  10  of this invention may be adapted to include a single tensioner  26  for situations whereby it is desirable to apply tension to a single flexible member, such as at a post or wall which terminates a fence line being erected. In this instance, as shown in  FIG. 4 , the device  10  may be provided with a single tensioner  26  and only one end portion of the top  12  and bottom  14  plates. The rectangular spacing plate  16  is shortened, and the aperture  18  is retained for mounting. All other aspects of the device are the same as previously described.  
         [0025]     In an alternate embodiment of the invention, the body of the tensioning device  10  is articulated such that each tensioner  26  may be rotated relative to the attachment point of the device  10 . In this embodiment, the body of the tensioning device  10  is articulated to allow each tensioner  26  to be adjusted approximately  30  degrees above or below a midline of the device  10 . As best seen in  FIG. 5 , the body of the tensioning device  10  comprises two segments  13 , each comprising a top plate  15  and a bottom plate  17  separated by spacing plate  19 . As described above, top plate  15  and bottom plate  17  form a retaining means for a rotary tensioner  26 . Thus, each segment  13  includes both a rotary tensioner  26  at a first end and a connecting means  23  or bolt  23  for hingedly connecting to another segment  13 . Connecting means  23  may be any suitable connector such as a bolt, lag bolt, or screw, which advantageously may be also utilized to attach the tensioning device  10  to a support structure  52  such as a fence post  52 .  
         [0026]     The two overlapping portions of spacing plate  19  are interconnected to each other by a bushing  21 . Bushing  21  is formed with an elongated hole  18  or aperture  18  in its center to permit insertion of a bolt  23 , lag bolt  23  or screw  23 . The elongated hole  18  permits the attachment of the tensioning device  10  onto a post  52  and the tensioner  10  relative to the post. The tension in the first flexible member  50  is increased until the device  10  shifts to a first end of elongated hole  18  and, thereafter, the second flexible  50  member is tightened until the bolt  23  or other connector is centered in the elongated slot  18  without causing a bind with the bolt  23 . Thereby, the tensions of the two flexible members  50  are equalized.  
         [0027]     In embodiments of the invention best shown in  FIGS. 2 and 4 , toothed ratchet wheel  32  may be releasably secured to rotary member  27 . In this embodiment, rotary member  27  extends beyond the tensioning device  10  a sufficient distance to allow capture of the ratchet wheel  32  between the tensioning device  10  and any suitable retaining means. Accordingly, ratchet wheel  32  may be placed over rotary member  27  and secured with a cotter pin  46  passed through apertures  48  in an end of rotary member  26 .  
         [0028]     Reference is now made to use of a presently preferred embodiment of the present invention. The interior curved portion A of tensioning device  10  is placed in contact with support structure  52 , such as a fence post  52 , and loosely affixed thereto with a suitable fastener, such as a standard lag bolt or wood screw  23 , of appropriate size and strength inserted through aperture  18  in spacing plate  16  into said support structure  52 . A flexible member  50  such as the polymer fencing is inserted into slot  34  of each rotary member  26 .  
         [0029]     A lever, such as a suitable ratcheting lever (not shown), may be inserted into opening  44  contained within retainer flange  28  and used to turn rotary tensioner  27 , thereby applying a desired amount of tension to said flexible member  50 . As rotary tensioner  27  is turned, pawl  38  comes into contact with and engages a tooth  33  of ratchet wheel  32 . Pawl  38  consecutively engages the teeth  33  of ratchet wheel  32  to prevent slippage and, hence, any loss of tension in the flexible members  50 .  
         [0030]     It must be appreciated that the square-ended  39  shape of pawl  38  and ratchet wheel  32  having ratchet teeth  33  to engage the square end  39  of pawl  38  provide an additional advantage in tensioning a flexible member  50 . Due to the shape generally exhibited by the teeth of most ratchet wheels, ordinary pawl and ratchet systems allow a certain amount of play or backlash as the pawl passes over one tooth of the ratchet wheel and, by reversing rotation of the ratchet wheel to engage the pawl in the ratchet tooth, locks between that tooth and the adjacent tooth on the wheel. For most systems incorporating pawl/ratchet systems, this is of no concern. However, in this application described herein, any amount of play before the pawl  38  locks the ratchet  32  in place would undesirably result in loss of tension in the flexible member  50  being tensioned. In contrast, in this invention the angle of the teeth of ratchet wheel  32  exactly matches the proximal end  39  of pawl  38  in the locked position. Therefore, as best seen in  FIG. 2 , at the instant pawl  38  passes over the tip of a tooth  33  of ratchet wheel  32 , pawl  38  is immediately urged into engagement with ratchet wheel  32  with no slippage or loss of tension in the flexible member being tensioned.  
         [0031]     The process is repeated with the second flexible member  50 . As it will be appreciated from  FIGS. 5 and 6 , in the process of applying tension, the tensioning device  10  will automatically adopt the same angle as the contour of the land along which the flexible members  50  are stretched. It should also be appreciated that aperture  18  allows the tensioning device  10  to move laterally during tensioning if greater tension is applied to one side or the other of the device  10 . Advantageously, this allows the considerable stress caused by tensioning the opposed flexible members  50  to be placed upon the tensioning device  10 , rather than on the support structure. Upon achieving suitable tension in the opposed flexible members  50 , the fastener  23  maybe tightened, completing the process. Moreover, it should also be appreciated that, it is possible to return and apply additional tension to the flexible members  50 , thereby accommodating for loss of tension over time caused by stretching of the flexible members  50 .  
         [0032]     It should also be appreciated that by use of the articulated embodiment of the invention as shown in  FIGS. 5 and 6 , during tensioning, it is possible to adjust the angle at which each tensioner  26  is placed relative to a fence post  52 , further improving the ability of both the tensioning device  10  and flexible members  50  attached thereto to adapt to the contours of the land on which fencing is placed.  
         [0033]     Finally, as noted above in a preferred embodiment, the tensioning device  10  is substantially C-shaped. As best seen in  FIG. 2 , this configuration results in rotary tensioner  26  being offset in relation to spacing plate  16 .  
         [0034]     The foregoing description of various preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention when interpreted in accordance with the breadth to which it is fairly, legally and equitably entitled.