Patent Abstract:
A throwable ball having a large internal passage aligned with its central axis. An insert defines the bounds of the internal passage. This insert is surrounded by compressible foam that gives the ball an easy gripping surface. Interlock features are preferably provided between the insert and the compressible foam so that they do not slip relative to each other.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of sports. More specifically, the invention comprises an oblong throwing ball containing a large central passage that is bounded by a rigid material, with the outer portions of the ball being made of compressible foam. 
     2. Description of the Related Art 
     Spherical balls have been used in many sports and many amusement games. An example is the pressurized spherical ball used in the international game of football (known in America and some other regions as “soccer”). A spherical ball obviously rolls well and is easy to kick and otherwise manipulate with the feet. However, it is not easy to throw a large spherical ball. 
     The game of American football initially used a pressurized ball having an oblong shape. The original American football was similar in size and shape to the ball presently used in the sport of Rugby. However, as the forward pass evolved in American football during the first half of the 20 th  century, the ball began to change as well. The ball evolved to include distinct point at each end and a more slender shape. This allowed the ball to be more easily gripped and thrown. 
     The modern American football has a distinct central axis, with points at each end lying along this central axis. A skilled passer can release the ball so that (1) the ball&#39;s central axis is parallel to its flight path, and (2) the ball&#39;s center of rotation coincides with its central axis. When these two conditions exist, the passer has achieved a “tight spiral.” When the two conditions do not exist, the ball appears to “flutter.” This is true primarily because the leading point of the ball does not lie on the axis of rotation. Instead, it rotates around the axis of rotation, This eccentricity of rotation tends to persist throughout the flight of the ball. It significantly increases drag and also reduces directional stability. A badly eccentric throw is often called a “wounded duck.” For the same amount of initial velocity, it will not travel nearly as far as a “tight spiral.” 
     Thus, significant skill is required to correctly throw a modern American football. The exterior surface of such a football is also relatively rigid and requires a strong grip to throw effectively. It would be advantageous to provide a football having a more compressible exterior surface that could be more easily gripped. It would also be advantageous to provide a football having eccentricity-correcting features so that the ball would tend to stabilize in flight even when thrown poorly. The present invention provides these features as well as additional features. 
     BRIEF SUMMARY OF THE PRESENT INVENTION 
     The present invention comprises a throwable ball having a large internal passage aligned with its central axis. A relatively rigid insert defines the bounds of the internal passage. This insert is surrounded by compressible foam that gives the ball an easy gripping surface. Interlock features are preferably provided between the insert and the compressible foam so that they do not slip relative to each other. 
     The diameter of the internal passage is large in comparison to the overall diameter of the ball. The diameter of the internal passage is preferably at least 50% of the overall diameter. Although the insert extends for most of the length of the ball, it does not extend to the two ends. The ends only contain the compressible foam. This prevents injury or damage when the ball strikes something. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view, showing the inventive ball in an assembled state. 
         FIG. 2  is a perspective view, showing the insert alone. 
         FIG. 3  is an elevation view, looking down the central axis of the assembled ball. 
         FIG. 4  is a sectional elevation view. 
         FIG. 5  is an elevation view, showing the inventive ball from the side. 
         FIG. 6  is a transverse elevation view, illustrating the diameter of the central passage in comparison to the ball as a whole. 
       
         
           
                 
               
                 
                 
                 
               
             
                 
                     
                 
                 
                   REFERENCE NUMERALS IN THE DRAWINGS 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                     
                   10 orb ball 
                   12 central passage 
                 
                 
                     
                   14 insert 
                   16 rib 
                 
                 
                     
                   20 insert containment step 
                   22 central axis 
                 
                 
                     
                   26 air flow 
                   28 foam body 
                 
                 
                     
                   30 passage diameter 
                   32 overall diameter 
                 
                 
                     
                   34 first end 
                   36 second end 
                 
                 
                     
                   38 exterior profile 
                   40 first insert end 
                 
                 
                     
                   42 second insert end 
                   44 chamfer 
                 
                 
                     
                   46 fillet 
                   48 compression region 
                 
                 
                     
                   50 insert recess 
                   52 insert passage 
                 
                 
                     
                   54 foam body passage 
                 
                 
                     
                     
                 
               
            
           
         
       
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a perspective view of the present invention, designated as orb ball  10 . The orb ball has an outward facing surface that is generally similar to the surface of an American football. it also includes central passage  12  a cavity running completely through the ball along its central axis. The orb ball includes two major components that are locked together. A relatively rigid insert forms the “core” of the ball. This insert is surrounded by pliable, high-density foam. 
       FIG. 2  shows a perspective view of insert  14  by itself. Insert  14  includes a cylindrical side wall defining a hollow internal passage. In the completed assembly it is surrounded by the high-density foam. The insert is preferably made from a relatively rigid material, such as an injection molded thermoplastic. The term “relatively rigid” refers to the relative rigidity of the insert with respect to the surrounding foam. 
     It is preferable to provide one or more interlocking features that will help lock the insert and the surrounding foam together. In the embodiment shown a pair of ribs  16  extend radially outward from the cylindrical wall. The foam is typically molded around the insert so the foam—while still in a non-set state—flows around the ribs. When the foam sets, the ribs create a mechanical interlock. 
       FIG. 3  provides an elevation view looking in a direction that is parallel to the orb ball&#39;s central axis. The reader will observe how central passage  12  extends through the orb ball. In addition, the reader will observe that the diameter of the central passage is quite large with respect to the overall diameter of the orb ball. 
       FIG. 4  is a sectional elevation view of the orb ball taken along the central axis. The reader will observe that all the features of the embodiment shown are radially symmetric about central axis  22 . As stated previously, insert  14  primarily consists of a cylindrical wall. The cylindrical wall has an inward facing surface and an outward facing surface. The inward facing surface of the cylindrical wall defines insert passage  52 . 
     Foam body  28  includes a cylindrical foam body passage  54 . Foam body passage  54  opens into a cylindrical insert recess  50 . The insert recess is a cylindrical recess that does not extend for the entire length of the foam body. Instead, it stops at two insert containment steps  20 . The first insert containment step abuts first insert end  40  and the second insert containment step abuts second insert end  42 . These abutting relationships—along with the ribs on the insert—create a good mechanical interlock between the insert and the foam body. 
     Surface adhesion between the insert and the foam body may also assist in the creation of the desired interlock. This surface adhesion may be created by a variety of processes, including molding the foam over the insert or the use of a separate spray-on or liquid adhesive. 
       FIG. 4  serves to illustrate several significant features of the invention. First, the reader will note that exterior profile  38  has a varying diameter. It is intended to resemble the exterior shape of the central portion of an American football. This portion of an American football has an elliptical profile, where the major axis of the defining ellipse is parallel to central axis  22  but also offset from the central axis. 
     Exterior profile  38  has a maximum diameter in the center of the orb ball. This diameter tapers toward either end of the ball. The diameter of the internal passage remains constant (or nearly so). Foam body  28  extends to first end  34  and second end  36 . However, in the embodiment shown, the elliptical exterior profile  38  does not extent all the way to the ends of the orb ball. Instead, a chamfer  44  is included proximate first end  34  and second end  36 . In addition, a fillet  46  is used to join the extreme end of each chamfer to foam body passage  54 . 
     As shown in  FIG. 4 , insert  14  does not extend all the way to the two ends of the orb ball. Instead, it stops short. First end  34  of foam body  28  extends well beyond first insert end  40  and second end  36  extends well beyond second insert end  42 . This extension creates a compression region  48  on each end of the orb ball. The compression region helps reduce the risk of injury or damage when the orb ball strikes something. The rigidity of the insert maintains the overall shape of the orb ball. However, the portions of the orb ball that may actually strike an external object (the exterior profile and the two ends) remain pliable. 
       FIG. 5  shows an elevation view of the orb ball looking in a direction that is perpendicular to central axis  22 . When the ball is thrown, the central passage allows air flow  26  through the interior of the ball. Air flows over the exterior of the ball in a conventional fashion. 
       FIG. 6  shows a sectional elevation view through the “fattest” portion of the orb ball—taken in a direction that is transverse to the central axis. Passage diameter  30  is shown, as is overall diameter  32 . In the preferred embodiment, passage diameter  30  is greater than half the value of overall diameter  32 . In an even more preferred embodiment, the passage diameter is greater than 55% of the overall diameter. 
     Those skilled in the art will understand the principles of angular momentum. In viewing  FIG. 6 , the reader will note that most of the orb ball&#39;s mass is concentrated near its perimeter rather than along its central axis. This fact provides greater spin-stability for a given overall mass. 
     Looking back at  FIG. 4 , those skilled in the art will discern another significant operational feature of the orb ball. As mentioned in the background section, an American football that is launched with an eccentric rotation (the ball&#39;s central axis being misaligned with the direction of flight) will tend to become less stable in flight. The orb ball&#39;s configuration produces the opposite result. 
     When the orb ball is thrown, air flows through its central passage with considerable velocity. The central passage acts like a wind sock, in that it will always tend to align itself with the prevailing flow. The prevailing flow is of course determined by the direction of the orb ball&#39;s flight. Thus, the flow through the central passage acts like a yaw damper for an imperfect throw. The term “imperfect throw” may apply to several conditions including: (1) The ball&#39;s axis of rotation is angularly offset from central axis  22 , (2) The ball&#39;s central axis is misaligned with the direction of flight, and (3) combinations thereof. 
     For any of these conditions the flow of air through the orb ball&#39;s central passage will tend to damp the error. In other words, the flow through the central passage will tend to (1) Shift the ball&#39;s axis of rotation so that it lies on the central axis, and (2) Align the central axis with the direction of flight. These stabilizing forces tend to reduce drag and increase the range of a particular throw. A further drag reduction results from the fact that the central passage reduces the orb ball&#39;s projected frontal area. 
     Still looking at  FIG. 4 , the reader may wish to know some of the manufacturing processes that can be used to create preferred embodiments of the invention. Injection molding may be used to create insert  14 . The insert may be molded as a solid body or may be “foam molded”—meaning that gas bubbles are injected into the liquid thermoplastic to create a rigid cellular structure. This technique creates a strong and light structure reminiscent of animal bone in that it has a solid exterior but a porous interior. 
     Foam body  28  may be created using an overmolding process. In overmolding, the completed insert is placed into a larger mold cavity. A liquid foam molding agent is then added to the cavity. The foam molding agent transitions to a solid while still in the mold. The unified assembly is then removed from the mold. 
     Insert  14  may be made of any desired thermoplastic. It could also be made using a thermoset material or a cross-linking material. For that matter, insert  14  could even be made of a metal such as aluminum. 
     Foam body  28  is preferably made from a high-density compressible foam. A suitable foam has a density in the range of 20 kilograms per cubic meter up to 60 kilograms per cubic meter. An even more preferable range lies between 30 kilograms per cubic meter and 50 kilograms per cubic meter. A foam&#39;s density is largely dependent upon the cell site in comparison to the cell wall thickness. A variety of techniques can be used to determine this value in order to bring the foam into the desired range of density. A wide variety of foams could be used. Examples include HDPE (high-density polyethylene) and polyurethane foams. 
     Overmolding tends to produce a good surface bond between the insert and the foam body. The assembly may be created in other ways, however. For example, the foam body could be separately molded and then connected to the insert. The foam body is quite pliable so the insert could be slipped into the interior and snapped into position. A separate adhesive could also be used to facilitate the surface bond. 
     Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. One skilled in the art may easily devise variations on the embodiments described. Thus, the scope of the invention should be fixed by the claims rather than the examples given.

Technology Classification (CPC): 0