BACKGROUND OF THE INVENTION 
     The present invention relates to dumbbell weights and in particular to an orbital dumbbell weight having weight offset from a centered handle. 
     Exercising with weights has become recognized as generally benefitting all ages of humans regardless of any desire for bodybuilding. Such weight training has been shown to improve muscle and bone density providing health benefits such as reducing osteoporosis with age. Unfortunately, is it often difficult to visit a gym regularly and significant space is required to set up an exercise room at home. Therefore, a need exists for compact exercise equipment that can be used at home. 
     One form of compact equipment is the dumbbell. Because the dumbbell is used with a single arm, significant weight is not required to obtain a benefit. However, the effect of common dumbbells is limited by the weight of the dumbbell. Kinetic dumbbells have been developed having rotating weighted ends with offset weights. When motion is used to cause the weighted ends to rotate, the rotating weight excises the user&#39;s muscles more than merely lifting the dumbbell. 
     U.S. Pat. No. 6,837,833 for “Specialty Weight Training Apparatus and Method” discloses such a kinetic dumbbell. While the &#39;833 dumbbell provides the benefits of rotating offset weights, the design of &#39;833 dumbbell includes threading the weighted ends (circular wheel-weights 30) onto an axle 20. Such threaded attachment makes it difficult to align the weighted ends. 
     U.S. Pat. No. 3,482,835 for “Barbell With Eccentrically Weighted Weights” discloses a kinetic dumbbell with a radially extending screw 5 bearing against a shaft 6 to allow aligning the weighted ends. Such use of a screw 5 is prone to slipping allowing the weighted end to become miss-aligned and requiring correction. Thus a need is present for a kinetic dumbbell which effectively retains the weighted ends in alignment. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing a kinetic dumbbell which includes offset weighted ends keyed to a single axle and a grip residing over the axle and between the weighted ends. The axle and weighted ends are free to rotate with respect to the grip. The weighted ends include slots accepting weights to adjust an offset weight of each weighted end. A timer/counter may be attached to one end to signal a user that an exercise is completed. The axle is attached to the weighted ends using a key through the axle, the key residing in channels in the weighted ends to rotationally fixing the axle to each weighted end, and screws and washers to hold the weighted ends on the axle. Bushings reside over the axle and engage each end of the handle to position the handle on the axle. 
     In accordance with one aspect of the invention, there are provided offset weighted ends having slots to accept weights. The weights are an interference fit into the slots and covered by end plates. 
     In accordance with another aspect of the invention, there are provided pins pressed through holes in the axle, and residing in channels in each weighted end. The channels are in interior faces of the weighted ends and prevent the weighted ends from rotating with respect to the handle, thereby fixing the respective alignment of the weighted ends. 
     In accordance with one still another aspect of the invention, a screw, lock washer, and flat washer are used to retain plastic weighted ends on the axle. The flat wash is selected to have sufficient strength and surface area to distribute attaching force over a sufficient area of plastic to prevent mechanical failure. 
     In accordance with yet another aspect of the invention, there are provided pear shaped weighted ends. The pear shape prevents the dumbbell from rolling away when dropped on a floor or after being placed on a flat surface for storage, for example, on a table or desk. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1A  is a perspective view of a kinetic dumbbell according to the present invention. 
         FIG. 1B  is a perspective view of the kinetic dumbbell according to the present invention with a cover removed. 
         FIG. 2A  is a side view of the kinetic dumbbell according to the present invention. 
         FIG. 2B  is an end view of the kinetic dumbbell according to the present invention. 
         FIG. 3A  is a detailed outside side view of a pear shaped offset weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 3B  is a detailed inside side view of a pear shaped offset weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 4  is a cross-sectional view of the pear shaped offset weighted end of the kinetic dumbbell according to the present invention taken along line  4 - 4  of  FIG. 3A . 
         FIG. 5A  is a side view of a timer attachable to the pear shaped offset weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 5B  is a top view of the timer attachable to the pear shaped offset weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 6A  is a side view of an axle assembly of the kinetic dumbbell according to the present invention. 
         FIG. 6B  is second a side view of the axle assembly of the kinetic dumbbell according to the present invention rolled 90 degrees. 
         FIG. 7  show a cross-sectional view of an engagement of the one end of the axle assembly engaging one of the pear shaped offset weighted ends according to the present invention, taken along line  7 - 7  of  FIG. 2B . 
         FIG. 8A  is a rear view of a bushing of the axle assembly according to the present invention. 
         FIG. 8B  is a front view of the bushing of the axle assembly according to the present invention. 
         FIG. 8C  is a side view of the bushing of the axle assembly according to the present invention. 
         FIG. 9  shows a weight according to the present invention for use with the kinetic dumbbell. 
         FIG. 10  shows a cross-sectional view of a handle of the kinetic dumbbell according to the present invention. 
         FIG. 11A  shows a front view of an adjustable weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 11B  shows a rear view of the adjustable weighted end of the kinetic dumbbell according to the present invention. 
         FIG. 12  shows a cross-sectional view of the adjustable weighted end of the kinetic dumbbell according to the present invention taken along line  12 - 12  of  FIG. 11B . 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     A perspective view of a kinetic dumbbell  10  according to the present invention is shown in  FIG. 1A  and perspective view of the kinetic dumbbell  10  with a cover  16  removed is shown in  FIG. 1B . The kinetic dumbbell  10  includes pear shaped offset weighted ends  14  and a handle  12  between the ends  14 . The cover  16  covers cavities  24  which receive weights  60  (see  FIG. 9 ) allowing both the total weight, and the weight distribution of the kinetic dumbbell  10  to be adjusted to a user&#39;s preference. For example, weight may be added as a user gains strength or becomes more accustom to using the kinetic dumbbell  10 . The weights  60  are preferably an interference fit to the pear shaped offset weighted ends  14 . The covers  16  preferably press onto the pear shaped offset weighted ends  14 , but may be attached using screws and the like. Two recessed areas  18  in outside faces  14   a  of each pear shaped offset weighted ends  14  allow easier grasping of the kinetic dumbbell  10 . 
     A side view of the kinetic dumbbell  10  is shown in  FIG. 2A  and is an end view of the kinetic dumbbell  10  is shown in  FIG. 2B . The pear shape of the offset weighted ends  14  prevents the kinetic dumbbell from easily rolling away when dropped or set onto a floor. 
     A detailed outside side view of a pear shaped offset weighted end  14  of the kinetic dumbbell  10  is shown in  FIG. 3A , a detailed inside side view of a pear shaped offset weighted end  14  is shown in  FIG. 3B , and a cross-sectional view of the pear shaped offset weighted end  14 , taken along line  4 - 4  of  FIG. 3A , is shown in  FIG. 4 . The outside face  14   a  includes the recesses  18 , the cavities  24 , an optional timer recess  28 , and an axle recess  26  and axle passage  27 . The rear face  14   b  includes a channel  20  for an axle key  40  (see  FIGS. 6A ,  6 B, and  7 ) which positions the pear shaped offset weighted end  14  with respect to the axle  34  and keeps the pear shaped offset weighted ends  14  from independently rotating and from rotating on the axle  34 . The axle recess  26  includes a shoulder  26   a  for an axle washer  42  (see  FIG. 6A ). 
     A side view of a timer  28  attachable to one of the pear shaped offset weighted ends  14  is shown in  FIG. 5A  and a top view of the timer  28  is shown in  FIG. 5B . The timer  28  includes a button  30  for starting the timer and may have a single function or a selectable function, for example based on pressing the button more than once, or holding the button down. For example, the timer  28  may provide an audible signal after a period of time, or after sensing motion. The length of the period of time may be increased by pressing the button  30  multiple times, or by holding in the button. 
     A side view of an axle assembly  32  of the kinetic dumbbell  10  is shown in  FIG. 6A , a second a side view of the axle assembly  32  rolled 90 degrees is shown in  FIG. 6B , and a cross-sectional view of an engagement of the one end of the axle assembly  32 , engaging one of the pear shaped offset weighted ends  14 , taken along line  7 - 7  of  FIG. 2B  is shown in  FIG. 7 . The axle assembly  32  includes an axle  34 , and opposite ends  35  of the axle  34  passing through the inside face  14   b  of each weighted end  14 , bushings  50 , spring (or wave) washers  38 , and keys  40 , and against the outside face  14   a  of each weighted end  14 , a flat washer  42 , a lock washer  44  and a fastener  46 . The bushing  50  is described in greater detail in  FIGS. 8A-8C . 
     The spring washers  38  straddle the keys  40  and are compressed between the bushings  50  and the ends  14 . The thickness of the spring washers may be selected to vary a resistance of the ends  14  to rotate on the handle  12 . The combination of the weights  60  and the spring washers  38  allow the kinetic dumbbell  10  to be assembled to match a user&#39;s preferences. 
     The axle  34  is preferably a steel axle, about 0.43 inches in diameter, and 9.4 inches long, having female threads in opposite ends. The spring washers  38  reside between the bushing  50  and the weighted ends  14  increasing manufacturing tolerance and providing a snug fit of the handle  12  between the weighted ends  14 . The keys  40  are preferably round pins and more preferably rolled pins press fit into holes through the axle  34 . In one embodiment, the rolled pins are about 1.5 inches long and 0.2 inches in diameter. 
     The flat washers  42  are preferably about 0.75 inches in diameter and about 0.075 inches thick. The thickness being greater than a typical washer to provide additional strength. The lock washers  44  and fasteners  46  are preferably ¼ inch or M6 size. 
     A rear view of the bushing  50  is shown in  FIG. 8A , a front view of the bushing  50  is shown in  FIG. 8B , and a side view of the bushing  50  is shown in  FIG. 8C . The bushing  50  is made from plastic and has an outward facing shoulder  52  facing the weighted ends  14 , a tapered portion  54  facing the handle  12  and tapering from about 1.7 inches in diameter to about 1.4 inches in diameter away from the weighted ends  14  toward the handle  12 . An inward facing shoulder  56  about 0.91 inches in diameter reaches into the handle  12  abutting against a metal liner  62  inside the handle  12  (see  FIG. 10 ). A face  55  separates the tapered portion  54  from the shoulder  56  and abutts against a soft outer material  64  of the handle  12 . A coarsely knurled tapered shoulder  58  extends inward from the shoulder  56 , for example, having four axially extending rounded raised surfaces separated by four axially extending rounded indentations. The shoulder  58  is pressed into the metal liner  62  having an interference fit. 
     The weighted end  14  is sandwiched between the spring washer  38  and the flat washer  42 , distributing the force against the weighted end  14 . A cylindrical bushing  60  is press fit into the outside end of the bushing  50  and rides on the axle  34  providing easy rotation of the handle  12  on the axle  34 , the bushing may be, for example, a bronze bushing. 
     A weight  60  for use with the kinetic dumbbell  10  is shown in  FIG. 9 . The weight  60  is made in various lengths and is an interference fit into the cavities  24  of the weighted end  14  (see  FIG. 3A ). 
     A cross-sectional view of the handle  12  of the kinetic dumbbell  10  is shown in  FIG. 10 . The metal liner  26  is pressed over the tapered shoulder  58  and the soft outer material  64  abuts against the face  55 . 
     A front view of an adjustable weighted end  70  of the kinetic dumbbell is shown in  FIG. 11A , a rear view of the adjustable weighted end  70  is shown in  FIG. 11B , and a cross-sectional view of the adjustable weighted end  70  taken along line  12 - 12  of  FIG. 11B  is shown in  FIG. 12 . The adjustable weighted end  70  includes a family of channels  20  and a slot  72  for an axle end  35  (see  FIG. 6A ). The channels  20  preferably include at least one offset channel for attaching the handle  12  to the adjustable weighted end  70  providing offset weights for use as a kinetic dumbbell, and at least one channel  20  providing centered weights for use as a standard dumbbell. Those skilled in the art will recognize that a handle may be attached to an adjustable end in various manners, both having discrete fixed locations as provided by the channels  20 , and continuously adjustable locations, and any dumbbell allowing such adjustment is intended to come within the scope of the present invention. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
A kinetic dumbbell includes offset weighted ends keyed to a single axle and a grip residing over the axle and between the weighted ends. The axle and weighted ends are free to rotate with respect to the grip. The weighted ends include slots accepting weights to adjust an offset weight of each weighted end. A timer/counter may be attached to one end to signal a user that an exercise is completed. The axle is attached to the weighted ends using a key through the axle, the key residing in channels in the weighted ends to rotationally fixing the axle to each weighted end, and screws and washers to hold the weighted ends on the axle. Bushings reside over the axle and engage each end of the handle to position the handle on the axle.