BEACH TENNIS RACQUET WITH HITTING SURFACE TO SIMULATE TENNIS STRINGS

Abstract

A beach tennis racquet is disclosed having a handle and frame enclosing a striking element. The striking element is a composite comprising a core and a plurality of ultrathin carbon fiber layers that are fused into a solid surface of no more than two millimeters in thickness. The striking surface is centered in the frame of the racquet and inset from the frame in a manner similar to a tennis racquet.

Claims

1. A beach tennis racquet comprising: a handle; a frame attached to the handle, the frame defining a hitting area; and a composite striking element located within the frame in the hitting area, the composite striking element comprising a non-woven core, first and second sheets of a material selected from fiberglass and carbon fiber applied to and covering first and second sides of the core, and third and fourth sheets of a material selected from fiberglass and carbon, fiber applied to and covering the first and second sheets; wherein a maximum thickness of the composite striking element is no greater than two millimeters.

2. The beach tennis racquet of claim 1, wherein the composite striking surface has a coefficient of restitution of greater than 0.7.

3. The beach tennis racquet of claim 1, wherein the third and fourth sheets have a surface area that is greater than a surface area of the first and second sheets.

4. The beach tennis racquet of claim 1, further comprising fifth and sixth sheets of a material selected from fiberglass and carbon fiber, the fifth and sixth sheets applied to and covering the third and fourth sheets.

5. The beach tennis racquet of claim 4, wherein the fifth and sixth sheets have a surface area that is greater than the surface area of the third and fourth sheets.

6. The beach tennis racquet of claim 5, wherein the maximum thickness of the composite striking element is less than 1.5 millimeters.

7. The beach tennis racquet of claim 5, wherein the maximum thickness of the composite striking surface is approximately one millimeter.

8. The beach tennis racquet of claim 1, wherein the composite striking element is centered at an inner wall of the frame.

9. The beach tennis racquet of claim 1, wherein the composite striking element includes holes located around a central area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is an exploded view of a first preferred embodiment of the present invention;

[0008] FIG. 2 is an elevated, perspective view of the embodiment of FIG. 1;

[0009] FIG. 3A is a cross sectional view of the embodiment of FIG. 2 taken along line 3-3;

[0010] FIG. 3B is an enlarged, cross sectional view of the juncture of the striking element and the frame; and

[0011] FIG. 4 is an elevated, perspective view of a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 1 illustrates an exploded view of a first high performance beach tennis racquet of the present invention. The racquet comprises a lightweight frame 12 that is attached to a handle 14, which may be wrapped with leather, synthetic leather, foam, cloth, or other grippable material. The striking element of the racquet is comprised of seven distinct layers that are formed into a composite to simulate strings on a tennis racquet. The innermost layer of the striking element is the core, the thickest of the layers at approximately one millimeter. The core may be a resilient material of non-woven polymer, although other cores can be used of natural or synthetic materials such as cork, wood, foam, etc. Onto the core at both exposed surfaces is an ultra-thin layer of carbon fiber 22 of the same size as the core 20. These layers of carbon fiber 22 have another layer of carbon fiber 24 covering the exposed surfaces of the previous layers, again of equal size to the previous layers 20, 22. A third layer of carbon fiber sheets 26 is then applied to the top and bottom of the previous layers, where the third layer has a larger surface area than the previous layers to extend to the frame's 12 perimeter in the undeformed condition. The multi-layer composite striking element 40 is then heated to fuse the layers together and to enclose the inner layers with the frame 12. The result is a striking element 40 that is preferably less than two millimeters and more preferably on the order of one millimeter in thickness after heating. The racquet 10 (FIG. 2) thus has a striking element that comprises a multi-layer composite with a core and fused layers of carbon fiber that is inset within the frame of the racquet like strings on a tennis racquet, and completely fills the area of the frame 12. FIG. 4 illustrates an alternate embodiment of a racquet 50 where post-heating through holes 52 have been punched into the striking element 40 around the “sweet spot” 56 to make the racquet even more aerodynamic.

[0013] FIG. 3A shows a cross sectional view of the racquet 10 taken along lines 3-3 of FIG. 2. The thickness “t” of the striking element 40 has a maximum value of two millimeters and is preferably less than one and one half millimeters. Conventional paddles could not be used with thicknesses in this range with any material that would also yield a resilient playing surface, and the present inventors are aware of no other paddle having a construction of this type. The striking element 40 is attached to the inner wall 13 of the frame 12 using the outermost carbon fiber layer 26 as best seen in FIG. 3B. The outer fiber layer 26 is larger than the inner layers and when heated and pressure is applied forms an attachment to the inner wall 13 of the frame. A portion 26a of the outermost carbon layer 26 adheres to and covers a portion of the inner wall 13 and forms a seal for the other layers as shown.

[0014] The foregoing construction provides a high performance beach tennis racquet 10 that most closely simulates a stringed racquet such as those used in tennis. To compare, the evolution of research on tennis equipment has recently introduced some parameters for the evaluation of the racket's efficiency. Among them, the most used in current practice is the coefficient of restitution of the racket (COR), that is simply defined as the ratio of the rebound speed to the incident speed of the ball for orthogonal impact. The COR can be affected by the conditions of balls and the tension of strings, but high end racquets fall within well-established ranges.

[0015] The coefficient of restitution (COR) can be derived considering the energy loss during impact. The main sources of energy loss are E.sub.1 and E.sub.2 due to the instantaneous large deformation of a ball and racquet which is calculated by using the coefficient e.sub.BG. If a ball collides with a racket at rest (VRo=0), the energy loss E.sub.2 could be easily obtained. The coefficient of restitution e.sub.r corresponds to the total energy loss E (=E.sub.1+E.sub.2) obtained as e.sub.r=(Y.sub.R−V.sub.B)/V.sub.BO=[1-2E (m.sub.B+M.sub.r)/(m.sub.BM.sub.r V.sub.BO)].sup.1/2

[0016] High end tennis racquets can achieve a coefficient of restitution of between 0.75 to 0.83 for a conventional weight and weight balanced racket [International Scholastic Journal of Science 9 (1) January December, 2015]. Conversely, COR for rubber surface paddles have a COR in the range of 0.5-0.65 [Procedia Engineering 147 (2016) 348-353]. In the racquet of the present invention, the COR was found to be in the range of 0.7-0.8, significantly above the best paddles. The ultra-thin hitting surface of the racquet of the present invention provides a tennis string type response using a flat, solid hitting surface to greatly improve the performance of the racquet.

[0017] While several preferred embodiments of the invention have been disclosed and depicted, it is to be understood that the invention is not limited to the embodiments shown in the drawings or described herein unless expressly limited. For example, the layers of the striking element about the core can be fiberglass instead of carbon fiber, or another suitable thin sheet material that provides a suitable response and exhibits proper wear characteristics. Accordingly, the scope of the invention is properly determined by the appended claims, using the ordinary meanings of the words consistent with, but not limited by, this specification.