Abstract:
A disk shaped quiet bumper plate for a barbell has a rim of elastomeric material with a shock absorber region. The shock absorber region has a circumferential row of evenly spaced transverse holes. The material between the holes forms radial walls which act as shock absorbers when the bumper plate is dropped. This reduces noise without unduly increasing bounce.

Description:
COPYRIGHT AND TRADEMARK NOTICE 
       [0001]    A portion of the disclosure of this patent document contains material to which a claim for copyright is made. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but reserves all other copyright rights whatsoever. The term “Stealth” is a trademark of Sound Shore Innovations L.L.C. 
       FIELD OF THE INVENTION 
       [0002]    Embodiments of the present invention relate to weight training equipment. 
       BACKGROUND OF THE INVENTION 
       [0003]      FIG. 1  is a front perspective view of a prior art bumper plate  100 . A bumper plate is a disk shaped weight that is mounted on a bar bell for weight training. The bumper plate comprises an outer rim  102 , body  104 , hub  106  and collar  108 . The collar describes a central bar hole  110 . The interface between the rim and body comprises an undercut  114 . Thus the thickness of the body may be somewhat less than the thickness of the rim. The interface between the body and the hub comprises a step  116 . Thus the hub may have a larger thickness than the body. The larger thicknesses of the rim and hub relative to the body allow for raised indicia  120  to be molded into the body. The hub and rim protect said indicia when the bumper plate lies flat on the ground. The undercut also acts as a handle to make it easier to lift the bumper plate. The outer edge of the rim comprises a bevel  112 . This makes it easier to pick up the bumper plate when it is lying flat on the ground. 
         [0004]    A typical bumper plate may have a radius  122  in the range of 8.75 inches to 8.86 inches. 8.86 inches is a standard size for competition. The bar hole radius  126  is about 1 inch. The hub radius  124  is about 4.26 inches. The rim height  132  is about 1.77 inches. The undercut is about 0.43 inches. The rim thickness  136  may be in the range of 1.4 inches to 3.75 inches depending upon the weight of the bumper plate. 
         [0005]    The bumper plate may be made of solid rubber, bonded crumb rubber, polyurethane or other elastomer. The durometer of the elastomer may be in the range of 70 to 90. The collar may be made of metal. The hub may comprise a metal disk plate for extra weight. 
         [0006]    One of the drawbacks of the prior art bumper plate design is that there is a tradeoff between the noise made when the bumper plates are dropped on the floor and the amount of bounce in the bumper plates after they hit the floor. Low durometer elastomers (e.g.  70 ) are relatively quiet, but they have a high bounce which can lead to injury. High durometer elastomers (e.g.  90 ) have a low bounce, but can make a very loud noise when dropped. Thus there is a long felt need for a bumper plate design that has both low bounce and low noise when dropped. 
       SUMMARY OF THE INVENTION 
       [0007]    The summary of the invention is provided as a guide to understanding the invention. It does not necessarily describe the most generic embodiment of the invention or the broadest range of alternative embodiments. 
         [0008]      FIG. 2  is a front perspective view of a quiet bumper plate  200 . The bumper plate is disk shaped with a shock absorber region  220  in the rim  202 . The shock absorber region comprises a first circumferential row of first holes  222 . The holes pass transversely through the rim and are evenly spaced. The holes in this example are hexagonal, but any shape may be used. The internal corners of the hexagons are rounded to reduce cracking. A suitable internal radius of curvature of the internal corners  242  is in the range of 0.02 inches to 0.05 inches. The elastomeric material between the holes forms radial walls  224 . These act as shock absorbers when the bumper plate is dropped on the ground thus reducing the noise emitted without unduly increasing bounce. For bumper plates with a radius of about 8.75 inches or greater, a suitable first hole width  226  is in the range of 0.5 inches to 0.75 inches. A suitable hole spacing  228  is in the range of 0.75 inches to 1.5 inches. A suitable wall width  230  is in the range of 0.13 inches to 0.5 inches. A suitable wall height  232  is in the range off 0.5 inches to 1 inch. 
         [0009]    A second circumferential row of second holes  234  may be provided adjacent to the row of first holes. The second holes pass transversely through the disk. The second holes form a plurality of circumferential walls  236  with the first holes. These provide additional shock absorbing capability. 
         [0010]    Additional rows of holes may be provided. The holes do not have to be the same shape or size within a given row. A suitable overall height of the shock absorber  238  region taken up by the rows of holes may be in the range of 0.5 inches to 1.5 inches. 
         [0011]    Sufficient clearance  254  should be provided between the first holes and the outer radial surface of the disk  256  to form a skin  252 . A suitable skin thickness is in the range of 0.06 inches to 0.25 inches. Larger thicknesses can be used for stronger skins. The outer radial surface may also comprise radial projections that can act as shock absorbers. 
         [0012]    The quiet bumper plate may comprise a rim  202 , body  204 , hub  206  and collar  208 . An undercut  212  may be provided at the interface of the rim and body. A step  214  may be provided at the interface of the body and hub. The dimensions of the rim, body, hub, collar, undercut and step may be similar to the dimensions of the corresponding features of the prior art bumper plate of  FIG. 1 . The undercut and step recess the body relative to the rim and hub so that raised indicia  216  may be provided in the body. A bevel (not shown) may also be provided on the outer corner of the rim. 
         [0013]    In order to keep the same plate radius and weight as the prior art, the thickness  244  of the plate a may be increased to account for the loss of material from the holes. Higher density materials may be also be added. An example is metal plates provided at the hub or internal to the bumper plate to increase overall density without unduly increasing thickness. 
         [0014]    The quiet bumper plate may be made of an elastomer, such as rubber, pressed crumb rubber, poly urethane or mixtures thereof. Durometers may be in the range of 60 to 90. Lower durometer elastomers may be used in bumper plates designated for home use. This will help keep the noise to levels acceptable in homes. A different durometer may be used in the shock absorber region relative to the rest of the quiet bumper plate. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a front perspective view of a conventional bumper plate. 
           [0016]      FIG. 2  is a front perspective view of an embodiment of a quiet bumper plate. 
           [0017]      FIG. 3  is a front perspective view of an alternative embodiment of a quite bumper plate. 
           [0018]      FIG. 4  is a side perspective view of an embodiment of a quiet dumbbell. 
           [0019]      FIG. 5  is a side perspective view of an alternative embodiment of a quiet dumbbell. 
           [0020]      FIG. 6  is a side perspective view of an embodiment of a quiet kettlebell. 
           [0021]      FIG. 7  is a front perspective view of an alternative embodiment of a quiet kettlebell. 
           [0022]      FIG. 8  is a side perspective view of a crescent shock absorber. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The detailed description describes non-limiting exemplary embodiments. Any individual features may be combined with other features as required by different applications for at least the benefits described herein. 
         [0024]    As used herein, the term “about” means plus or minus 10% of a given value unless specifically indicated otherwise. 
         [0025]    As used herein, the term “shaped” means that an item has the overall appearance of a given shape even if there are minor variations from the pure form of said given shape. 
       ALTERNATIVE EMBODIMENTS 
       [0026]      FIG. 3  is a front perspective view of an alternative quiet bumper plate  300 . This is similar to the quiet bumper plate of  FIG. 2  except the shock absorber region  302  comprises first holes  304  with an elongated inverted trapezoidal shape. The first holes are evenly spaced circumferentially. Radial walls  306  are formed between the holes. The radial walls have a relatively wide base and narrow top. 
         [0027]      FIG. 4  is a side perspective view of a quiet dumbbell  400 . The dumbbell comprises a conventional hexagonal weight dumbbell  404  with a shock absorber  402  wrapped around each weight. The dumbbell may be made of metal and the shock absorber may be made of an elastomer. The holes in the shock absorber are similar to the holes in the quiet bumper plate of  FIG. 2 . 
         [0028]      FIG. 5  is a side perspective view of an alternative quiet dumbbell  500 . The dumbbell comprises a conventional hexagonal weight dumbbell  404  with a shock absorber  502  wrapped around each weight. The dumbbell may be made of metal and the shock absorber may be made of an elastomer. The holes in the shock absorber are similar to the holes in the quiet bumper plate of  FIG. 3 . 
         [0029]    The shock absorbers for either quiet dumbbell may have flat outer surfaces for stacking (not shown). 
         [0030]      FIG. 6  is a side perspective view of a quiet kettlebell  600 . The kettlebell comprises a conventional kettlebell  604  with several shock absorber crescents  602  wrapped around the weight. The kettlebell may be made of metal and the shock absorber crescents may be made of an elastomer. The holes in the shock absorber crescents are similar to the holes in the quiet bumper plate of  FIG. 2 . The crescents may be attached to the kettlebell by any known means, such as gluing.  8  crescents are provided radially and join at the bottom of the kettlebell. Sufficient crescents are applied so that the metal kettlebell within the crescents does not hit the ground when dropped. 
         [0031]      FIG. 7  is a front perspective view of an alternative quiet kettlebell  700 . The kettlebell comprises a conventional kettlebell  604  with several shock absorber crescents  702  wrapped around the weight. The kettlebell may be made of metal and the shock absorber crescents may be made of an elastomer. The holes in the shock absorber crescents are similar to the holes in the quiet bumper plate of  FIG. 3 . The crescents may be attached to the kettlebell by any known means, such as gluing.  8  crescents are provided radially and join at the bottom of the kettlebell. 
         [0032]    Flat sheets of elastomers with shock absorber regions may be used as mats. The shock absorber regions may be similar to the ones described above. Thus when a weight is dropped on the mat, the mat will suppress noise without unduly increasing bounce. The shock absorber mats may be made by extrusion. 
       Example 1 
       [0033]      FIG. 8  is a side perspective view of a crescent shock absorber  800  made according to the current invention. The crescent has a thickness  810  of about 1 inch. It has a height  812  of about 1 inch. It has an arcuate shape with a crescent angle  806  of about 90°. The radius of curvature to the inside surface  808  is about 8.75 inches. Thus the crescent would conform to the outer curvature of the prior art bumper plate of  FIG. 1 . A single row of evenly spaced hexagonal first holes  811  is provided. The hole spacing  814  is about 1 inch. The hole width  816  is about 0.63 inches. The radial walls between the holes each have a width  818  of about 0.38 inches. The skin thickness  822  is about 0.13 inches. A first half of a reclosable 3M™ DualLock™ fastener  804  is provided on the inside surface of the crescent. The first half was mated to the corresponding second half of the DualLock fastener that was bonded to the outer radial surface of a conventional bumper plate similar to the one shown in  FIG. 1 . The crescent was formed by molding a thermoplastic elastomeric compound, Stantoprene™ 101-64 (item  802 ). The rated durometer of the Stantoprene was Shore A 69. 
         [0034]    A first test was done with a conventional barbell weighing 135 lb. The barbell had a bumper plate on each end of the style shown in  FIG. 1 . The barbell was dropped from a height of 4′10 inches onto a rubber stall mat covering a poured concrete floor. The noise of the impact was measured with a decibel meter. 136 dB was recorded when the barbell was dropped without any crescent shock absorbers on the bumper plates. 
         [0035]    A second test was run with four crescent shock absorbers attached to the outer radial surfaces of the bumper plates on the barbell using the DualLock fasteners. The crescents wrapped around the outer surface of each bumper plate. The drop test was repeated. The noise recorded was only 95 dB without an undue increase in bounce. 
       CONCLUSION 
       [0036]    While the disclosure has been described with reference to one or more different exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt to a particular situation without departing from the essential scope or teachings thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention.