Abstract:
A tire chain tightener for use on automotive, truck, or other vehicle traction chains and similar devices. The tire chain tightener has an length of elastic material with a hook attached to each end. Intermediate hooks are spaced along the elastic material between the two ends. One of the ends may be uniquely marked with instructions for correct installation of the tire chain tightener. When correctly installed, a tire chain tightener with N+1 hooks will form a symmetrical N pointed star inscribed in the circumference of the tire chains. The star is further centered about the tire. The tire chain tightener exerts a centering force on the tire chains. Since only one hook at a time is installed, the effort to install the tire chain tightener is reduced, enabling people of limited strength to install them.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the provisional application entitled “Tire Chain Tightening Apparatus and Method” by Steven Dennis Moore, Ser. No. 61/279,055 filed Oct. 15, 2009 and hereby this reference is included in its entirety. 
     
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable 
       SEQUENCE LISTING 
       [0004]    Not applicable 
       FIELD OF THE INVENTION 
       [0005]    This invention relates to tire chain tighteners for traction chains used on cars, trucks and other vehicles. 
       BACKGROUND OF THE INVENTION 
       [0006]    Traction devices are used in slippery conditions such as snow, ice and mud. Devices such as diamond chains, link chains, cable chains, traction cables, snow cables and similar devices are herein collectively referred to as tire chains or simply chains. The chains generally fit around the outside of the tire on the tread and are pulled tightly to hold them against the tire. To further tighten the chains against the tire, tire chain tighteners of various types are used to pull the circumference of the tire chains toward the center of the tire. 
       SUMMARY OF THE INVENTION 
       [0007]    A tire chain tightening apparatus, also known as a tire chain tightener, is disclosed. It significantly reduces the movement or working of the tire chains, and reduces the unbalancing of the tire at higher rates of speed. Also reduced are the need to re-tighten the chains and incidences of chain breakage. The tire chain tightener uses a length of elastic material, sometimes referred to as a rope, with hooks attached to each end. A number of intermediate hooks are spaced between the ends and are attached to the length of elastic material. The total number of hooks on the elastic material can vary with the application. In one embodiment the intermediate hooks are arranged such that the elastic material enters each of the intermediate hooks from the direction of the first end and exits the intermediate hooks toward the direction of the second end. This arrangement reduces the wear on the elastic material where it enters and leaves the intermediate hooks. The hook on one end of the elastic material can be marked in some way to indicate the correct installation. Some embodiments use an intermediate hook with an eye, made to contain two passes of the elastic material. A typical eye is in the shape of an oval. A loop of elastic material can pass though the eye and go around a shank that extends outwardly from the eye. The shank further rises out of the plane of the eye to make a J-shaped hook. The plane of the J portion is usually perpendicular to the plane of the eye. In some embodiments, the open hook end of the J-shaped exceeds 180° of curvature. This can reduce the wear of the open hook against a tire. The hook can be manufactured from bent wire, injection molding, casting or other processes. Other embodiments can use an “S”, double facing “U” or other hook designs for the intermediate hooks. 
         [0008]    In use the user identifies a number of points spaced around the circumference of the tire chains when they are installed on a tire. If there are N points, a tire chain tightener with N+1 total hooks is employed. The hook at one end is first attached to one of the identified points. The next hook in line on the elastic material is attached to another point on the tire chains such that the last hook attaches at about the same point as the first hook. When properly installed, the tire chain tightener forms a symmetrical N pointed star pattern centered about the tire. 
         [0009]    The procedure for attaching the tire chain tightener starts with identifying N points around the circumference of the tire chains. A direction, clockwise or counter clockwise, is determined by which of the end hooks is marked. The marked hook at one end of the tightener attaches to a first of the N points. By moving along the circumference of tire chain, the next hook along the elastic material attaches to the next point encountered or to the 2nd, 3rd, 4th, 5th, 6th or 9th point depending upon the total number of points N. By moving around the circumference of the tire chains and attaching the next hook to the appropriate point, the user eventually reaches the starting point with the first hook. The result is the symmetrical N pointed star pattern centered about the tire. Together, the hooks and elastic material pull the circumference of the tire chains toward the center of the tire thus tightening the chains against the tire. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The summary above, and the following detailed description will be better understood in view of the enclosed drawings which depict details of preferred embodiments. Like reference numbers designate like elements. It should however be noted that the invention is not limited to the precise arrangement shown in the drawings and that the drawings are provided merely as examples. The features, functions and advantages can be achieved independently in various embodiments of the claimed invention or may be combined in yet other embodiments. 
           [0011]      FIG. 1  shows one embodiment of the tire chain tightener. 
           [0012]      FIG. 2  shows an exemplary installation of the tire chain tightener on a tire with tire chains. 
           [0013]      FIG. 3  shows one aspect of the geometry of the tire chain tightener. 
           [0014]      FIG. 4  shows one aspect of the geometry of a prior art design. 
           [0015]      FIG. 5  shows one embodiment of a wire hook used in the tire chain tightener. 
           [0016]      FIGS. 6A-6G  show an example installation of an elastic material in the hook of  FIG. 5 . 
           [0017]      FIGS. 7A and 7B  show alternative embodiments of hooks used with the tire chain tightener. 
           [0018]      FIGS. 8A-8G  show the steps of installing one embodiment of the tire chain tightener on a set of tire chains. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows an exemplary embodiment of the tire chain tightener  100 . The tightener  100  has six hooks labeled H 1 , H 2 , H 3 , H 4 , H 5  and H 6 . The six hooks H 1  through H 6  are connected together by a linear elastic material  110  which has a first end  120  connected to a first hook H 1  and a second end  130  attached to hook H 6 . To distinguish between the first end and second end, the first end has a marker  140 . A number of intermediate hooks labeled H 2  through H 5  are attached to the linear elastic material spaced between the first end  120  and the second end  130 .  FIG. 1  shows an embodiment with six hooks. Other embodiments with different numbers of hooks are also possible. 
         [0020]      FIG. 2  shows one embodiment of the tire chain tightener  100  attached to the circumference  230  of a set of tire chains  220 . Five points P 1 , P 2 , P 3 , P 4 , and P 5  spread around the circumference  230  of the tire chains  220 . The six hooks of the tire chain tightener H 1 , H 2 , H 3 , H 4 , H 5 , and H 6  attach to the five points P 1 - P 5  on the tire chain circumference  230  forming a symmetrical five pointed star inscribed in the circumference  230  of the tire chains  220 . The five pointed star is centered about the tire center  210 . In this example the number N equals five, the number of points of the star, while the number N+1 equals six or the number of hooks on the tire chain tightener. 
         [0021]      FIG. 3  is a geometric abstraction of the tire chain tightener  100  of  FIG. 2 . The circumference  230  of the tire chains in  FIG. 2  are represented in  FIG. 3  by the circumference  230  of the circle. In  FIG. 3  point P 1  has two line segments E 1  and E 2  representing the elastic material of  FIG. 2  which terminates in ends  120  and  130 . Each of the segments E 1  and E 2  assert a tension T at P 1 . The angle ⊖ between E 1  and E 2  is 36°. The force exerted on point P 1  toward the center C is 2*T*Cos(⊖/2). While this example shows a five pointed star giving ⊖=36°, smaller values of N result in a smaller value of ⊖. N is the number of points on the circumference of the circle representing the points on the circumference of the tire chain in  FIG. 2 . 
         [0022]    Note that, for a given tension, T, as N increases, corresponding to an increased number of points on the star, two things happen:
       1) The total Force F increases with increasing N.   2) The value of the Cosine function approaches one, the maximum possible value of the Cosine function.       
 
         [0025]    This is good in that more center directed force may be obtained by increasing the number of points on the circumference of the tire chains. As the number of points increases, the center directed force increases rapidly. 
         [0026]      FIG. 4  is a geometric abstraction of a prior art tire chain tightener. The tightener of  FIG. 4  is a loop of elastic material with five hooks. Each of the hooks connect to one of the five points P 1 , P 2 , P 3 , P 4 , and P 5 . The angle φ is the internal angle of the regular polygon inscribed in the circle. The value for φ is: φ=((N−2)*180)/N. Again N is the number of points on the circumference. Thus, for an N pointed regular polygon with a tension T in all the elastic segments, the total force acting in the direction of the center C is: 
         [0000]        F= 2 *N*T *Cos((( N− 2)*180)/ N ) 
         [0027]    Note in the equation above, for a given tension, T, as N increases, corresponding to an increased number of points on the polygon, two things happen:
       1) The total Force F increases with increasing N.   2) The value of the Cosine function approaches zero, the minimum absolute value of the Cosine function.       
 
         [0030]    This is problematic in that as the number of points increases, the center directed force increases slowly because the cosine function approaches zero. The various embodiments of the present invention overcome this disadvantage and as will be explained later, make installation easier. 
         [0031]    Refer again to the tire chain tightener  100  of  FIG. 1 . The elastic material  110  can be made from a number of materials including, but not limited to, synthetic or natural rubbers. In some embodiments a metal or plastic spring also works. A purpose of the elastic material is to exert a force along its length when it is stretched. In preferred embodiments, the elastic material  110  is a length of material as opposed to a closed loop. The length depends upon the number of points on the intended star pattern and the size of the tire chain circumference  230 . An efficacious length is easily determined by one skilled in the art using the values of tire chain circumference, number of points on the star, the elastic property of the elastic material and the force the user wishes to exert during installation. 
         [0032]    The elastic material has two ends,  120  and  130 . A first hook H 1  attaches to the first end  120 . This attachment can be accomplished in a number of ways including, but not limited to, knots, clamps and crimps. In a similar manner the second end  130  attaches to hook H 6 . Note that for an application intended for a N pointed star, the number of hooks will be N+1 or one hook more than the number of points on the intended star.  FIG. 1  shows six hooks for an application intended for a five pointed star. Exemplary values of N include 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19, although other values are possible. The larger the value of N, the more centered directed force is ultimately possible. 
         [0033]    Four hooks H 2 , H 3 , H 4 , and H 5  are spaced between the first end  120  and the second end  130 . Note that for the five pointed star of  FIG. 2 , there are N−1, or four hooks between H 1  and H 6  in  FIG. 1 . These intermediate hooks, H 2 , H 3 , H 4  and H 5  can be fixedly attached to the length of elastic material or slideably attached. In one embodiment the N−1 intermediate hooks are spaced substantially equally between the first hook H 1  and the N+1 hook H 6 . 
         [0034]    In one embodiment, the N−1 intermediate hooks are attached to the elastic material, such that they face the same direction. The elastic material enters each of the N−1 intermediate hooks from the direction of the first end  120  and first hook H 1 , and exits each of the N−1 intermediate hooks toward the direction of the second end  130  and N+1 hook H 6 . 
         [0035]      FIG. 5  shows an exemplary embodiment of a hook  500 . In this embodiment the hook  500  is made from a bent wire segment  505 . The wire segment  505  has a first end  560 , a second end  550  and an intermediate portion  540 . Other embodiments of the hook  500  include hooks made by casting, injection molding or other manufacturing methods. Possible materials include, but are not limited to, plastic, metal, and composites. The hook  500  has an eye  510  in the shape of an oval. In this context an oval means an ellipse, a race track shape or other similar shapes. The eye  510  lies in the first plane  570 , having a major width  514  parallel to the X-axis and a minor width  512  parallel to the Y-axis. The major width  514  is longer than the minor width  512 . In the embodiment of  FIG. 5  the eye  510  is contained in a first plane  570  and is adapted to contain two passes of the elastic material  110  of  FIG. 1 . In this embodiment the eye  510  has a major width  514  about two cross sectional widths of the elastic material  110 . The minor width  514  is about one cross sectional width of the elastic material  110 . The internal area of the eye  510  is adapted to contain two passes of the elastic material  110 . 
         [0036]    The intermediate portion  540  of the wire segment  505  bends in the oval shape to form the eye  510 . The first end  560  and second end  550  of the wire segment  505  extend outwardly from the eye  510  parallel to the Y axis. The first end  560  and second end  550  form a shank  520  and lie in the first plane  570  together with the eye  510 . 
         [0037]    At least one of the ends  550  or  560  extends beyond the shank  520  forming a J-shaped hook portion  530 . The J-shaped hook portion  530  is contained in a second plane  575 . The second plane  575  is perpendicular to the first plane  570  and is parallel to the minor width  512 . The J-shaped hook  530  rises out of the first plane  570  at an acute angle  532 . The J-shaped hook  530  further has a curvature of at least 180° as indicted by the arc and dashed line  534 . This curvature helps keep the end of the hook at the first wire end  560  from abrading a tire. 
         [0038]    The hook  500  of  FIG. 5  can be used for any of the hooks shown in  FIG. 1 . This includes the end hooks H 1  or H 6  as well as the intermediate hooks H 2 , H 3 , H 4 , and H 5 .  FIGS. 6A ,  6 B,  6 C,  6 D and  6 E show how the hook  500  of  FIG. 5  fits onto the elastic material  110 . In  FIG. 6A  a loop  610 , also called a bight, in the elastic material  110  fits into the eye  510  of the hook  500  and over the J-shaped hook portion  530 . In  FIG. 6B  the elastic material  110  slides down the J-shaped hook portion  530  and over the shank  520 . In  FIG. 6C  the loop of elastic material  110  pulls tightly around the shank  520 . In this manner the elastic material  110  is fixedly attached to the hook  500 .  FIGS. 6D and 6E  show other views of the elastic material  110  installed on the hook  500 . In installation on tire chains, an intermediate hook such as H 2  can be installed two ways. The first way shown in  FIG. 6F  shows the elastic material  110  entering and leaving the hook H 2  such that the elastic material does not cross over itself at the hook H 2 .  FIG. 6G  shows a case where the elastic material  110  does cross over itself as it enters and leaves the hook H 2 . By proper design and installation, the tire chain tightener can avoid this type of cross over, prolonging the life of the elastic material and the tire chain tightener itself. 
         [0039]    Other hook designs are possible.  FIG. 7A  shows an “S” hook and  FIG. 7B  shows a double facing “U” shaped hook. Openings of these two types of hook can be adjusted so that the elastic material is captured by the hook. The opening can be open enough to allow a the hook to fit slidingly over the elastic material or closed more tightly to have the hook fixedly attached to the elastic material. 
         [0040]    In use the user first decides on N, the number of points for the star pattern to be formed by the tire chain tightener. In  FIG. 2  for example, N=5. For a given tire chain tightener, the value of N will be one less than the number of hooks on the tire chain tightener. The method of forming the star pattern is not immediately obvious. The table below introduces a second number H which is a count number when installing the tire chain tightener. The H number is explained in the following example. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Hook Connection Chart 
               
             
          
           
               
                 N = Number of Points 
                 H = Next point at 
                 Expressed as 
               
               
                 in the Star pattern Around 
                 which to install 
                 ordered pair of numbers 
               
               
                 the Chain Circumference 
                 next hook 
                 (N, H) 
               
               
                   
               
             
          
           
               
                 3 
                 1 
                  (3, 1) 
               
               
                 4 
                 1 
                  (4, 1) 
               
               
                 5 
                 2 
                  (5, 2) 
               
               
                 7 
                 3 
                  (7, 3) 
               
               
                 8 
                 3 
                  (8, 3) 
               
               
                 9 
                 4 
                  (9, 4) 
               
               
                 10 
                 3 
                 (10, 3) 
               
               
                 11 
                 5 
                 (11, 5) 
               
               
                 12 
                 5 
                 (12, 5) 
               
               
                 13 
                 6 
                 (13, 6) 
               
               
                 14 
                 5 
                 (14, 5) 
               
               
                 15 
                 7 
                 (15, 7) 
               
               
                 16 
                 7 
                 (16, 7) 
               
               
                 17 
                 8 
                 (17, 8) 
               
               
                 18 
                 7 
                 (18, 7) 
               
               
                 19 
                 9 
                 (19, 9) 
               
               
                   
               
             
          
         
       
     
         [0041]    The tire chain tightener of  FIGS. 1 and 2  has six hooks. This implies that N equals five. Looking in the chart above in the row where N=5, one finds that H=2. This is expressed compactly with the ordered pair (N,H)=(5,2). 
         [0042]    The user then identifies N or five substantially equally spaced points P 1  through P 5 , around the circumference of the tire chains. This is shown in  FIG. 8A . 
         [0043]    The user then provides the appropriate tire chain tightener with a total of N+1 hooks. Two hooks are attached to the first and second ends of the elastic material as described earlier and N−1 intermediate hooks are attached to the elastic material, spaced between the first and second end hooks. 
         [0044]    Next the user chooses a rotational direction around the circumference of the tire based on the construction of the tire chain tightener. In this example the rotational direction  810  is counter clockwise. While either direction will work, the direction is chosen based on the entry and exit of the elastic material into and out of the eye of the hook. By choosing the correct rotational direction, the elastic material will not cross over itself as it enters and exits the eye of the hook. This reduces wear and rubbing of the elastic material when in use. 
         [0045]    The user then attaches the first hook to one point on the tire.  FIG. 8B  shows the first hook H 1  of the tire chain tightener connected to the first point P 1  on the tire chains  220 . 
         [0046]    Since H equals two for N=5, the user then counts two points past the last hook installed. Since the last hook installed was H 1  at point P 1 , the user counts in the counter clockwise direction  810  to the second point after P 1 . This is P 4 . The user then attaches the next hook on the tire chain tightener H 2  to point P 4  as shown in  FIG. 8C . 
         [0047]    Continuing with H equals two for N=5, the user then counts two points past the last hook installed. Since the last hook installed was H 2  at point P 4 , the user counts in the counter clockwise direction  810  to the second point after P 4 . This is P 2 . The user then attaches the next hook on the tire chain tightener H 3  to point P 2  as shown in  FIG. 8D . 
         [0048]    Continuing with H equals two for N=5, the user then counts two points past the last hook installed. Since the last hook installed was H 3  at point P 2 , the user counts in the counter clockwise direction  810  to the second point after P 2 . This is P 5 . The user then attaches the next hook on the tire chain tightener H 4  to point P 5  as shown in  FIG. 8E . 
         [0049]    The value of H is fixed for a given number of hooks on a tire chain tightener. Continuing with H equals two for N=5, the user then counts two points past the last hook installed. Since the last hook installed was H 4  at point P 5 , the user counts in the counter clockwise direction  810  to the second point after P 5 . This is P 3 . The user then attaches the next hook on the tire chain tightener H 5  to point P 3  as shown in  FIG. 8F . 
         [0050]    Finally, the user then counts two points past the last hook installed. Since the last hook installed was H 5  at point P 3 , the user counts in the counter clockwise direction  810  to the second hook after P 3 . This is P 1 . The user then attaches the next hook on the tire chain tightener H 6  to point P 1  as shown in  FIG. 8G . This completes the installation of the tire chain tightener forming the five pointed star. 
         [0051]    Note that in the example of  FIGS. 8A through 8G  several variations are possible. The intermediate hooks H 2  through H 5  between the two ends can be slideably or fixedly attached to the elastic material. Similar tensions in the segments of the elastic material between the hooks will result if the hooks are fixedly attached, with equal spacing between the hooks. If the intermediate hooks are slideaby attached, the tension throughout the elastic material will tend to equalize by itself. The selected points along the circumference of the tire chains does not need to be exact but can be approximate to give a workable star pattern. Similarly, the spacing between the hooks on the elastic material can also be approximate and still yield good results. 
         [0052]    Note also that when the user attaches one hook to the chain, that only one segment of the elastic material between two hooks is stretched at a time. This reduces the strength needed to stretch and hook the tire chain tightener onto the circumference of the tire chains. Other types of tire chain tighteners require the last hook installed to stretch two sections of elastic. This results in a greater force requirement and limits who is strong enough to install a tire chain tightener. The tightener disclosed herein has the advantage that people of lesser strength can still install it. 
         [0053]    To promote the proper installation of the tire chain tightener, the first hook attached to the first end, is uniquely identified, distinguishing it from the second end. This identification can take many forms such as a band, color or other identifying mark. The purpose of the identification is to avoid the cross over of the elastic material as it enters and exits the intermediate hooks. Avoiding this cross over, as discussed in conjunction with  FIGS. 6F and 6G  prolongs the life of the tire chain tightener. Also, for a pre-assembled tire chain tightener of N+1 hooks, the direction, clockwise or counter clockwise, and the count value H can be marked on the first end. For example, a colored identifying sleeve on the first hook of a six hook tire chain tightener could have “CCW-2”. This would indicate that the user installs the tire chain tightener working counter clockwise around the circumference of the tire chains, connecting the next hook to the second point encountered. 
         [0054]    It will be appreciated that the invention is not limited to what has been described herein above merely by way of example. While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various other embodiments, changes, and modifications may be made therein without departing from the spirit or scope of this invention and that it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention, for which letters patent is applied.