Patent Publication Number: US-2017361204-A1

Title: Wheel bearing

Description:
FIELD OF THE INVENTION 
     The present invention relates to a wheel bearing. In particular, although not exclusively, the invention relates to a bearing for a skateboard wheel and a skateboard wheel assembly. However, it will be appreciated that the wheel assembly can be used on other wheeled devices. 
     BACKGROUND TO THE INVENTION 
     Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge. 
     A large number of people, many of them children, suffer injuries whilst attempting to learn to ride a skateboard or similar wheeled device. Similarly, even more experienced riders are injured due to falls of numerous kinds but in this instance, particularly from the tendency of such wheeled devices to escape forward from under the rider rendering the rider prone to wrist, arm, spinal or head injuries. 
     Skateboards and similar wheeled devices are traditionally fitted with highly effective ball bearings in the wheels. These ball bearings have virtually no resistance to facilitate rolling in any condition, either static or dynamic. 
     As soon as a rider places any weight onto the riding deck of the board, the board has a natural tendency to roll and accelerate under the force of the rider&#39;s weight. If the rider is not quick and skilful enough to get both feet onto the board and balance between the two axles, the board has a tendency not only to move away from under the rider taking the rider&#39;s feet with it, but as the rider&#39;s weight moves behind the rear axle the downward and forward weight of the rider causes the board to accelerate rapidly propelling the rider&#39;s upper body and head backwards towards the ground. 
     OBJECT OF THE INVENTION 
     It is a preferred object of the present invention to provide an improved wheel bearing and skateboard wheel assembly that addresses, or at least ameliorates one or more of the aforementioned problems of the prior art and/or provides a useful or commercial alternative. 
     Other preferred embodiments of the present invention will become apparent from the following description. 
     SUMMARY OF THE INVENTION 
     In one form, although not necessarily the only or broadest form, the invention resides in a wheel bearing comprising: 
     a cup; 
     a cone received within the cup, the cone being of a complementary shape to the cup; and 
     a washer, the washer abutting a surface of the cone, wherein the cup, the cone and the washer each comprise a self-lubricating polymer. 
     In a second form, although not necessarily the only or broadest form, the invention resides in a skateboard wheel assembly comprising: 
     a wheel; 
     two wheel bearings diametrically opposed on two sides of the wheel, each wheel bearing including:
         a cup;   a cone received within the cup, the cone being of a complementary shape to the cup; and   a washer, the washer abutting a surface of the cone,       

     wherein the cup, the cone and the washer each comprise a self-lubricating polymer. 
     Preferably, a spacer is mounted between the two wheel bearings. More preferably, the spacer abuts the two wheel bearings. 
     Preferably, the washer includes a raised outer lip. 
     Preferably, the self-lubricating polymer includes acetal and ertalon. 
     Preferably, the cup includes a tapered inner side wall. 
     Preferably, the cone includes a tapered outer side wall complementary to the tapered inner side wall of the cup. 
     Preferably, the cone includes an upper face and a lower face at opposed ends of the cone. 
     Preferably, the tapered outer side wall extends between the upper face and the lower face of the cone. More preferably, the tapered outer side wall of the cone extends from the lower face to the upper face at an angle of between 45° to 85° relative to the lower face. Even more preferably, the tapered outer side wall of the cone extends from the lower face to the upper face at an angle of between 55° to 75° relative to the lower face. Suitably, the tapered outer side wall of the cone extends from the lower face to the upper face at an angle of between 65° to 75° relative to the lower face. 
     Preferably, the lower face of the cone abuts the washer. 
     Preferably, the cone is frustoconical. 
     In another form, although not necessarily the only or broadest form, the invention resides in a method for assembling a skateboard wheel comprising: 
     fitting a first cup into a first housing recess of a wheel; 
     fitting a first cone within the first cup; 
     fitting a first washer to the first cone, wherein the first washer abuts a surface of the first cone; 
     fitting a second cup into a second housing recess of the wheel, the first housing recess opposite the second recess; 
     fitting a second cone within the second cup, wherein the second cone abuts the first cone; 
     fitting a second washer to the second cone, wherein the second washer abuts a surface of the second cone. 
     Preferably, the method further comprises the step of fitting a spacer within the wheel, wherein the spacer abuts the first cone and the second cone. 
     Preferably, the method further comprises the step of fitting the skateboard wheel to an axle. 
     Preferably, the method further comprises the step of fitting a nut to the axle to secure the wheel in place. 
     Preferably, the method further comprises the step of applying a tackifying agent to each of the first and second cups. 
     Further features of the invention will become apparent from the detailed description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiment of the invention will be described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a skateboard wheel assembly according to an embodiment of the present invention; 
         FIG. 2  is a side view and an overhead view of the cone of the skateboard wheel assembly shown in  FIG. 1 ; and 
         FIG. 3  is an exploded view of the axle, washer, cone and spacer of the skateboard wheel assembly shown in  FIG. 1 . 
     
    
    
     Those skilled in the art will appreciate that minor deviations from the symmetrical layout of components as illustrated in the drawings will not detract from the proper functions of the disclosed embodiments of the present invention. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a skateboard wheel assembly  100 . The skateboard wheel assembly  100  includes a wheel  110  and two bearings  120  for a skateboard wheel  110 . Each bearing  120  includes a thrust washer  130 , a tapered cup  140  and a complementary tapered cone in the form of a frustocone  150  having a lower end  151 , an upper end (or tapered end)  152  and a tapered side wall  153  extending between the lower end  151  and the upper end  152  at angle of between approximately 45° to 85° relative to the lower face. 
     The frustocone  150  is received within the reciprocally shaped cup  140 . In some embodiments, the thrust washer  130  may also include a raised lip (not shown) at the outer edge which corresponds with the edge of the cup  140  of the bearing assembly  120 . 
     The thrust washer  130 , tapered cup  140  and frustocone  150  are typically composed of a self-lubricating polymer in the form of acetal and ertalon respectively. However, a person skilled in the art will appreciate that these elements can be composed of any suitably self-lubricating polymer. 
     The skateboard wheel assembly  100  further includes a spacer  160  that is mounted between the two wheel bearings  120  should the bearings  120  not meet. It will be appreciated that in some embodiments, where the two bearings  120  are of sufficient length to meet, the spacer  160  is not required. 
     Additionally, the skateboard wheel assembly  100  includes an axle  170  that extends through holes (not shown) in each of the wheel  110  and the two bearings  120 . Fitted to the end of the axle  170  and abutting the thrust washer  130  is an axle nut in the form of a wheel securing nut  180  to secure the bearings  120  and the wheel  110  in place. 
     The tapered cup  140  is pressed into the bearing housing recess  111  at the centre of each end  112 , 113  of the wheel  110 . The larger face, or lower end,  151  of the frustocone  150  faces out from the centre of the wheel  110  as shown. 
     In assembly, the thrust washer  130  and the frustocone  150  are fitted to the axle  170  with the tapered end  152  of the frustocone  150  facing away from the centre of the skateboard (not shown) and pushed onto the axle  170  until the frustocone  150  abuts the undercarriage (not shown) of the skateboard, from which the axle  170  protrudes on each side of the skateboard. 
     The cylindrical spacer  160  is fitted to the axle  170  with a first end  171  abutting the tapered end  152  of a first frustocone  150 . The wheel  110  with both tapered cups  140  is then placed onto the axle  170  over the spacer  160  and frustocone  150  in such a way as to have the cup  140  nearest to the centre of the skateboard sit over and align with the tapered end  152  of the frustocone  150  on the axle. 
     A second frustocone  110 , identical to the first frustocone  110 , is fitted to the axle  170  with the tapered end  152  facing the centre of the wheel  110 . This cone is pushed into a position such that the taper matches and sits into the taper of the cup  140  in the outer side of the wheel  110 . A thrust washer  130  is then placed on the axle  170  abutting the cone  150  as shown. In some alternative embodiments, the thrust washer is also a seal. 
     The wheel securing nut  180  is threaded onto the matching threaded end of the axle  170  and rotated until the washers  130 , frustocones  150  and spacer  160  press together along the axle  170  and resistance is felt as the wheel securing nut  180  is turned. This ensures that the washers  130 , frustocones  150  and spacer  160  are clamped together, locking the frustocones  150  from rotating and ensuring that the cups  140  rotate on the cones  150  focusing rotational friction at this point. 
     In some alternative embodiments, the washers, cones and cups can comprise a combination of different polymers. In use, this combination of polymers enhances the static grip of the bearing and provides improved polymer lubrication and freer movement as speed increases. 
     The polymers of the bearing can also be lubricated with a suitable grease type lubricant or tackifying agent (not shown). The lubricant binds to the sheared particles of the bearing preventing some of the sheared particles from redepositing into the polymer and therefore increasing the lubricating shear layer between the components of the bearing. This increases the pressure to velocity ratio of the polymers. 
       FIG. 2  illustrates a side view and an overhead view of the frustocone  150  of the bearing assembly  120  described in  FIG. 1 . As shown, an aperture  154  extends through each of the seal  130 , cup  140  and frustocone  150  for receiving the axle  170  shown in  FIG. 1 . 
       FIG. 3  illustrates an exploded view of the axle  170 , washer  130 , frustocone  150  and spacer  160  of the skateboard wheel assembly  100  described in  FIG. 1 . 
     Advantageously, the arrangement of the frustocones  150  and cups  140  result in a self-centering effect for the wheel when downward force is applied to the bearing  120 , for example, by a rider standing on the skateboard. 
     Further advantageously, when weight is applied to the bearing in a stationary condition, the force of static friction, enhanced by the tapered shape having the effect of increasing surface pressure at this point, has a tendency to prevent the bearing from turning. 
     Further, the removal of a ball within the bearing provides increased stability of the skateboard. 
     Advantageously, if assembled with a raised lip of the washer running on the corresponding edge of the tapered cup, the thrust washer provides progressive reduction of friction. Much in the same manner as a fishing reel drag provides initial resistance and then breaks free and allows relatively free movement on overload. For example, the washer initially provides high levels of friction to prevent the skateboard from rolling when downward force is applied, and the friction reduces as more force is applied to the skateboard in a forward motion and thus the skateboard wheel assembly. 
     Advantageously, as a rider becomes more competent in riding the skateboard, the washer can be replaced with a standard thrust washer making the board easier to move and ride. 
     While the wheel assembly within this specification has been described with regards to a skateboard, it will be appreciated that this is for illustrative purposes only and that the wheel assembly can be used for other wheeled device, such as scooters. 
     Additionally the washer is interchangeable with and functions in a superior fashion to many common fishing reel drag washers. 
     In this specification, adjectives such as first and second, left and right, top, bottom and side, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc. 
     In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. 
     The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. 
     As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.