Abstract:
This invention refers to a novel ballgame racket, especially a tennis racket, including a racket head formed by a tension frame with stringing, and also having a grip portion joining the tension frame, for example by means of a crossing and formed by a gripping shaft or a racket neck and a handle. The racket has a mechanism for tensioning the strings which includes a two part tension frame of the racket head. The frame has a closed hollow profile with a second wing like profile in touch with the closed profile with a damping element placed therebetween.

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to a ball racket, and more particularly, a tennis racket having a handle, a tension frame and stringing. The racket has a core and handle shaft connecting the handle to the tension frame. The tension frame has a profile for holding the strings in tension with a dampening mechanism for causing string tension 
     A ball racket (U.S. Pat No. 5,458,331) is already known with a tension frame forming the racket head that is of a two-part design, with an inner frame profile adjacent to the stringing and an outer frame profile in relation to the stringing on which the eyelets for fastening the strings forming the stringing are located. Both profiles overlap in such a manner that they form two chambers of variable volume extending along the tension frame between the two profiles on both sides from one plane of the stringing (stringing plane), which (chambers) are sealed toward the outside and can be pressurized by means of a valve with a fluid that is under pressure, for example with pressurized CO 2  gas. The purpose of this is to achieve the best possible tension. 
     The object of the present invention is to provide a ball racket, in particular a tennis racket, with improved playing properties. 
     SUMMARY OF THE INVENTION 
     To achieve this object, a ball racket with a racket head formed by a tension frame with stringing and by a handle element connecting to the tension frame is provided. The tension frame contains two parts in at least one portion of the racket head and has a tension frame profile adjacent to the stringing for holding the strings. The tension string profile holds the strings in a tensioned or dampened state. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     The invention is described in more detail based on sample embodiments in the following figures: 
     FIG. 1 is a simplified representation in top view of a ball racket according to the invention in the form of a tennis racket; 
     FIGS. 2 and 3 depict a cross section corresponding to line  1 — 1  of FIG. 1, before tensioning of the strings (FIG. 2) and after this tensioning (FIG.  3 ); 
     FIGS. 4 and 5 are representations similar to FIGS. 2 and 3, in an alternate embodiment of the invention; 
     FIGS. 6 and 7 both depict a cross section through the racket head or tension frame of a ball racket according to the invention in an alternate embodiment; 
     FIG. 8 depicts a cross section through the racket head or tension frame of a ball racket according to the invention in an alternate embodiment; and 
     FIG. 9 is a simplified representation of a cross section through the racket head or tension frame of a ball racket according to the invention in an alternate embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The tennis racket depicted in the figures and generally designated  1  is made up of: a tension frame  2  forming the racket head and having the stringing  3  located there, which is made up of numerous sections of string or strings  4  that cross each other; and of the racket neck or racket grip shaft  6  connected to the tension frame  2  or its tension frame profile  2 ′ or  2   a′  (FIGS. 2-5) above a core  5 , to which (shaft) the racket handle  7  is located. The tension frame profile  2 ′ or  2   a′ , the core  5 , which is formed by two bars or arms  5 ′ extending and diverging from the handle shaft  6 . The handle shaft  6  and core form a one-piece racket frame, which in the depicted embodiment is manufactured as a hollow body or hollow frame that is closed toward the outside and made of a suitable material, such as fiber-reinforced plastic material and has a hollow profile that is closed to the outside along its entire length. 
     As shown in FIGS. 2 and 3, an outer force-buffering support profile  8  is provided for on the tension frame  2  or tension frame profile  2 ′ that is on the outside in relation to the stringing  3 , which in the depicted embodiment encompasses the tension frame  2  or the tension frame profile  2 ′ along the entire long side of the tension frame  2  between the arms  5 ′ of the core  5 . The support profile  8 , in the depicted embodiment, is symmetrical to the stringing plane BE and is a hood-like profile section  9  that is open toward the stringing  3 , with a concave outer surface on its outer side facing away from the stringing  3  in the area of the stringing plane BE in the cross section view in FIGS. 2 and 3, in order to form a groove-like depression  10  that encloses the racket head or the tension frame  2  on the outside. On both sides of the depression  10 , the profile section  9  in the sectional view of FIGS. 2 and 3 has an essentially convex bend on the outer surface, so that it forms two sections on both sides of the stringing plane BE that both form a concave depression  11  on the inner side facing the stringing  3  in the sectional view of FIGS. 2 and 3 that likewise extends along the entire length of the support profile  8  parallel to the depression  10 . Furthermore, the support profile  11  has sleeves or eyelets  12  that are, for example, formed onto the side of the profile section  9  facing the frame  2 ′ and extend beyond this side. The eyelets  12  are inserted through bore holes  13  and  14  of the frame profile  2 ′, of which one bore hole  13  is arranged on the same axis as a bore hole  14  and the axes of which lie in the stringing plane BE. The eyelets  12  themselves have bore holes  15  through which the strings  3 ′ are guided in the manner common to the stringing of tennis rackets that in a given direction the respective string  4  extends outward through the bore hole  15  of an eyelet  12 , then within the depression  10  along the outer side of the tension frame and then through a further eyelet  12  or its bore hole  15  inward again etc. With the eyelets  12 , the support profile  8  can be adjusted within certain limits in the direction of the axis of the eyelets  12  in relation to the frame profile  2 ′. The tension frame  2  is therefore made of two parts along at least part of its length. The support profile  8  is formed by one piece extending along the total periphery of frame  2 . 
     As further shown in FIGS. 2 and 3, the profile  2 ′ on the outer side facing the profile section  9  is constructed on both sides of the stringing plane BE and at a distance from this with a groove-like depression  16 , each of which is located across from a depression  11 . In each depression  16  and therefore also in the corresponding depression  11  and between the outer surface of the frame  2 ′ and the inner surface of the supporting profile  8  or the profile section  9  there is an elastic element  17 . In the depicted embodiment each element  17  extends along the entire length of the supporting profile  8 . The elastic elements  17  are designed in such a way that when the supporting profile  8  is in a non-tensioned state and when the two outer edges  9 ′ of the profile section  9  are at a distance from profile  2 ′ (FIG.  2 ), and after stringing of the tennis racket  1 , i.e. especially after stringing of the strings  4 , the elastic elements  17  are pressed with an elastic or damping effect between the outer surface of the frame  2 ′ and the inner surface of the supporting profile  8  in such a way that the supporting profile  8  bears closely against the outer surface of the profile  2 ′ in the area of the edges  9 ′, so that the space  18  formed between the outer surface of the frame  2 ′ and the supporting profile  8  is closed, whereby however the tensile forces exerted by the stringing  3  or the strings  4  indicated by Arrow K in FIG. 3 are transferred across the supporting profile  8  and the elastic formed elements  17  onto the profile  2 ′. The elements  17  function not only as tension elements for maintaining the string tension, but also in particular as damping elements that provide an elastic damping of the impulse of a ball impacting on the stringing  3  or when striking the ball with the tennis racket  1 , which in particular also prevents disturbing shocks, vibrations etc. in the frame of the tennis racket  1 . 
     The elastic elements  17  can be, for example, of an elastic rubber material such as plastic, and are, e.g., corresponding lengths of a profile, for example a profile made of this material with a circular cross-section. The selection of material for the elements  17  is preferably such that it possesses not only elastic properties, but also damping or kinetic energy-consuming properties. 
     The elements  17  can also be hoses, for example, that are filled with a fluid, or with a gas or gas mixture, or with air or an inert gas (e.g. nitrogen or CO 2 ) and are tightly sealed. These hoses are then pressurized in the assembly state (FIG.  2 ), i.e. before tensioning the strings  4 , with a certain pressure, or remain non-pressurized. 
     Special effects result when the elements  17  are filled with a liquid medium, for example with a medium containing oil and/or water, so that in this case the supporting profile  8  gives in for a short time inward toward the stringing  3  at the position where the maximum tensile force is exerted on the strings  4  when the ball hits the stringing  3 , while in other non-affected or less affected areas of the stringing  3  the supporting profile  8  pressurizes across the elements  17  with an increased outward force due to the displaced liquid medium, causing an additional tension on the strings  4  here. This effect generally occurs when gas is used for filling. This results in completely new properties that are advantageous for a tennis racket  1 . 
     In the above description, it was assumed that the elements  17  are all continuous elements. It is also possible to divide each of these elements into a number of individual elements, which are then connected to each other in the direction of the supporting profile  8  and are fixed to each other in a suitable manner for ease of assembly, for example. 
     Furthermore, it is possible for the elements  17  to be part of a general profile, for example of a profile in which the two elements  17  are connected together as profile sections across a cross bar, which is indicated in FIG. 2 by the broken line  19 . Furthermore, it is possible for the elements  17  to be formed onto to the frame profile  2 ′ or the supporting profile  8 . 
     The supporting profile  8  must, as described above, be able to transfer the lateral forces K across the formed elements  17  to the frame. At the same time, however, the supporting profile  8  or its profile section  9  should still be sufficiently elastic at least in the area of the edges  9 ′ that a damping inward movement of the supporting profile  8  is possible by distortion of the elements  17  upon impacts or impulses on the stringing  3 . A suitable material for the supporting profile  8  would be a fiber-reinforced plastic material, metal or a composite material containing metal and plastic. In order to retain the required elasticity in the area of the edges  9 ′, the profile section  9  is constructed there, for example, with a reduced thickness and/or the reinforcement of the profile section  9  necessary for the transfer of force ends at a sufficient distance from the edges  9 ′. There is a wide variety of imaginable solutions to this problem. 
     In the case of a supporting profile, in which the profile section  9  is made of metal, the eyelets  12  are preferably made of plastic and are inserted or formed into the corresponding openings of the profile section  9 . In general, it is always possible to use a material for the eyelets  12 , preferably a plastic material, that possesses a considerably higher degree of flexibility or elasticity in comparison with the profile section  9 . 
     The eyelets  12  are, of course, designed in such a way that they tightly seal the interior of the frame  2 ′ at the points of insertion or the bore holes  13  and  14 . 
     As shown in FIGS. 2 and 3, the tension frame profile  2 ′ forms slanted bearing surfaces  2 ″ in the area of its outer sides, against which the profile section  9  of the supporting profile  8  bears in the area of the edges  9 ′ and which in the sectional view of FIGS. 2 and 3 both lie in one plane that forms an angle smaller than 90° with the stringing axis BE, opening toward the stringing  3 . This lessens the above-mentioned movement of the supporting profile  8  when the strings are tensioned relative to the tension frame profile  2 ′ under elastic deformation of the profile section  9 . 
     FIGS. 4 and 5 show as a further possible embodiment, a tennis racket in which the tension frame  2   a  again is designed in two parts, at least along part of its length, consisting of the actual, closed hollow frame  2   a′  and the supporting profile  8   a′  corresponding to the supporting profile  8 . 
     The essential difference of the embodiment in FIGS. 4 and 5, as compared with that depicted in FIGS. 2 and 3, is the fact that no bore holes  13  and  14  are implemented in the frame profile  2   a′ , but rather openings  20  extending from the outer side of the frame profile  2   a′  to the inner side of this frame profile and becoming larger in diameter toward the inner side of the frame profile  2   a′ , and which are closed by funnel-like wall sections  21  toward the interior of the frame profile  2   a′ . The supporting profile  8   a , accordingly, has only relatively short eyelets  12   a  that each are inserted into an opening  20 . Due to the openings that become larger at least in the cross-sectional axis perpendicular to the stringing plane BE, a lateral displacement of the corresponding string  4  during play is not possible, which for all practical purposes means an enlargement of the impact or stringing surface, among other things. 
     FIGS. 6 and 7 show in a representation similar to that of FIGS. 4 and 5 a cross-section through a tension frame  2   b  of a ball racket or tennis racket. The tension frame  2   b  has a frame profile  2   b′  corresponding to the frame profile  2   a′  and of the supporting profile  8   b , the function of which corresponds to that of the supporting profile  8   a . In the embodiment of FIGS. 6 and 7, instead of the flexible elements  17 , a flexible element  17   b  is provided for between the tension frame profile  2   b′  and the supporting profile  8   b  or the wing-like profile sections  9   b  of this supporting profile on both sides of the stringing plane BE. Both elements have, for example, a rail-like design and extend around the entire circumference of the tension frame  2   b  on which (circumference) this tension frame has a two-part design, i.e. consisting of the frame profile  2   b′  and the supporting profile  8   b . In the depicted embodiment the flexible elements  17   b  are made of an elastomeric material, for example of an elastic, plastic or rubber. 
     A suitable shape of the elastic elements  17   b  and a suitable shape of the space  18   b  formed between the frame profile  2   b′  and the supporting profile  8   b , occurs, when the strings  4  are under tension, the supporting profile  8   b  for fixing these strings on the tension frame  2  to be supported on the frame profile  2   b  when subjected to the elastic deformation of the elastic elements  17   b , while a distance  21  remains between the elastic elements  17   b  and the strings, i.e. the elastic elements  17   b  do not touch the strings, as depicted in FIG.  6 . 
     If extreme tensile forces are exerted on the stringing or on individual strings or string sections of this stringing when struck by a ball during play, then the resulting increased elastic deformation of the flexible elements  17   b  corresponding to FIG. 7 causes these elements  17   b  to bear against the strings  4 , whereby with the increased load on the strings also the force increases with which the flexible elements  17   b  are pressed against them. The radial fixing of the strings  4  results, upon increased force, in a significantly better sound of the ball racket or of the tensioned frame during play and also an improved damping of vibrations of the strings  4 , which also prevents or damps vibrations in the tension frame  2   b  excited by vibrations of the strings, thus significantly improving the overall vibration behavior of the racket or the racket frame. 
     In the above description it was assumed that the damping elements  17   b  are separate elements. It is generally also possible for these elements to be formed from a single rail-like element that possesses openings for lacing of the strings  4 . 
     FIG. 8 shows in a representation similar to that of FIGS. 6 and 7 a cross-section through a tension frame  2   c  of a ball racket or tennis racket. The tension frame  2   c  consists of the frame profile  2   c′  corresponding to the frame profile  2   b′  and of the supporting profile  8   c , the function of which is analogous to that of the supporting profile  8   b . A flexible element  17  is provided for between the tension frame profile  2   c′  and the supporting profile  8   c  or the wing-like sections  9   c  of this supporting profile on both sides of the stringing plane BE. The supporting profile  8   c  is again formed by one piece extending along the total periphery of frame  2 . The element  17  consists of a permanently elastic or elastomeric material, for example of an elastic or plastic, providing the required string tension due to its elasticity. 
     In the area of the stringing plane BE between the two elements  17 , a further element  17   c  is provided for that is supported on the one hand against the inner side of the supporting profile  8   c  and on the other hand in the area of a groove-like depression on the tension frame profile  2   c  that is open toward the circumference of this tension frame profile  2   c . The element  17   c , which in the depicted embodiment in non-tensioned condition has, for example, a circular cross-section and extends along the entire length of the supporting profile  8   c , is made of a material with damping properties, i.e. of a material that damps movements of the strings and also movements of the tension frame or of the tension frame elements, for example vibrations, impulses etc. The material of the element  17   c  is therefore such a material that is deformable, but expends kinetic energy upon being deformed. 
     As far as the element  17   c  is of a continuous design, this element contains openings for inserting the strings or the string eyelets. It is generally also possible for the element  17   c  to consist of several successive individual elements in the circumference direction of the tension frame  2   c , which are then located between the string eyelets not depicted in FIG.  8 . 
     The embodiment depicted in FIG. 8 therefore provides for the separation of the functional elements  17  for producing the string tension and the function element  17   c  for the damping of vibrations, impulses etc. Furthermore, as FIG. 8 shows, the frame profile  2   c  and the supporting profile  8   c  are designed in such a way that the free edges of the profile sections  9   c  overlap the frame profile  2   c  on the surfaces  22  that are parallel or roughly parallel to the stringing plane BE, so that a close outward seal of the space formed between the supporting profile  8   c  and the frame profile  2   c′  is guaranteed even with a relatively high degree of relative movement of the supporting profile  8   c  relative to the frame profile  2   c′  without deformation of the profile sections  9   c.    
     FIG. 9 shows as a further possible embodiment a cross-section through a racket head or tension frame  2   d  of a ball racket or tennis racket. The tension frame  2   d  consists of the closed frame profile  2   d′  and of the supporting profile  8   d , which in this embodiment is made of fiber-reinforced plastic, for example of fiberglass-reinforced plastic, in such a way that this supporting profile  8   d  or its wing-like sections  9   d  function as a spring, for example as a leaf spring. The support profile  8   d  is again formed by one piece extending along the total periphery of frame  2 . The tension frame profile  2   d′  has on the outer side of the tension frame a groove-like depression  23  that extends at least over part of the fame profile  2   d′ , on which the leaf spring supporting profile  8   d  is located. In the free ends, the profile sections  9   d  are supported in the depression  23 , so that the supporting profile  9   d  is secured against lateral displacement. The strings  4  of the stringing  3  are held in the middle of the supporting profile, for example by use of eyelets not depicted or an eyelet strip not depicted. 
     The embodiment in FIG. 9 differs from the embodiments of FIGS. 2-8 by the fact that the supporting element  8   d  made of fiber/composite material, e.g. of fiberglass composite material, is also designed as a spring element, so that the additional damping and tension elements are unnecessary. 
     The invention was described above using various exemplary embodiments. Of course, numerous modifications and adaptations are possible without abandoning the underlying inventive idea of the invention. For example, it is possible also in the area of the core  5  to construct the tension frame  2  or  2   a  in two parts in the manner illustrated in FIGS. 2 and 3 or  4  and  5 , i.e. to provide for a supporting profile  8  to  8   d  there on the outer side facing away from the stringing  3 . Furthermore, the frame profile and/or the supporting profile can, of course, have a design that deviates from the embodiments described above. The supporting elements can also made in sections joining each other along the periphery of the frame. In this case, the length of each section in the peripheral direction is larger than the width of the sections or the supporting element. 
     LIST OF REFERENCE TERMS 
       1  tennis racket 
       2 ,  2   a ,  2   b ,  2   c ,  2   d  tension frame 
       2 ′,  2   a′ ,  2   b′ ,  2   c′ , frame profile 
     
       2 
       d′ 
     
       3  stringing 
       4  string 
       5  core 
       5 ′,  5 ″ arm 
       6  handle shaft 
       7  racket handle 
       8 ,  8   a ,  8   b ,  8   c ,  8   d  supporting profile 
       9 ,  9   b ,  9   c  ,  9   d  profile section 
       10 ,  11  depression 
       12 ,  12   a  eyelet 
       13 ,  14  bore hole 
       15  bore hole 
       16  depression 
       17 ,  17   b ,  17   c  flexible and/or damping element 
       18 ,  18   b ,  18   c  space 
       19  cross bar 
       20  opening 
       21  opening or slit 
       22  surface 
       23  recess 
     BE stringing plane