Abstract:
A skate wheel (10) for use on in-line skates, conventional skates, skateboards, and the like. The wheel includes a centrally located hub (12). The skate wheel (10) also includes an annular interlock flange (14) integrally formed around the perimeter of the hub. Extended around a radial perimeter of the interlock flange is a tubular, radial reinforcement, such as a coil spring (18). The ends of the coil spring are joined to form a tubular ring concentric with the annular interlock flange. An elastomeric tire (20) envelops the coil spring.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to skate wheels and, in particular, to a skate wheel having internal radial support. 
     BACKGROUND OF THE INVENTION 
     Both speed and comfort are important considerations in the design of a skate wheel. To increase speed, the wheel, including an elastomeric tire secured around a hub assembly, should be designed to reduce rolling resistance. That is, the distortion of the elastomeric tire during skating should be lessened to reduce the surface contact between the tire and the ground, thereby reducing friction between the tire and the ground and increasing speed. 
     Prior attempts to reduce rolling resistance involved varying the diameter of the hub assembly of the wheel or providing an annular flange protruding perpendicularly from the hub assembly of the wheel into the tire interior. However, these attempts created a major drawback. The narrow profile of the annular flange limits its effectiveness in supporting the tire to reduce rolling resistance. Therefore, to support the tire more effectively, the diameter of the annular flange is greatly increased. However, the great increase in the diameter of the annular flange also causes a reduction in the rebound characteristics of the tire, making the wheel harsh to skate on with insufficient shock absorption. Either speed or comfort had to be sacrificed. 
     Thus, there exists a need for a skate wheel that reduces rolling resistance to increase speed, while maintaining the smoothness and comfort of the skating experience. 
     SUMMARY OF THE INVENTION 
     The present invention is a skate wheel for use on in-line skates, conventional roller skates, skateboards, and the like. The skate wheel has a centrally located hub. An annular interlock flange is integrally formed with the hub and protrudes radially about the perimeter of the hub. In a preferred embodiment, a coil spring is received within a groove defined about a radial perimeter of the annular interlock flange. The coil spring extends around the annular interlock flange and the ends of the coil spring are joined, preferably by welding or crimping, to form a tubular ring concentric with the annular interlock flange. An elastomeric tire is cast around the coil spring. 
     The diameter of the coil spring in relation to the thickness of the tire and the distance between the coil spring and the perimeter of the tire are such that the coil spring provides sufficient support for the tire to reduce rolling resistance, while permitting sufficient deflection to provide for grip between the tire and the ground. In addition, the shape of the coil spring approximates the perimeter of the tire to provide support more effectively and reduce deflection of the tire, while maintaining comfort for a user of the skates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a side view of a preferred embodiment of a skate constructed in accordance with the present invention, with the frame shown in phantom; 
     FIG. 2 is an enlarged side view of a wheel of the skate of FIG. 1, with the tire illustrated as translucent; 
     FIG. 3 is a cross-sectional view front view of the wheel of FIG. 2; 
     FIG. 4 is a side view of an alternative embodiment of a skate wheel; 
     FIG. 5 is a cross-sectional front view of the skate wheel illustrated in FIG. 4; and 
     FIG. 6 is a perspective view of another alternative embodiment of a skate wheel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, a skate  7  includes an upper shoe portion  8 , a frame  9  and a plurality of longitudinally aligned wheels  10  constructed in accordance with a preferred embodiment of the present invention. The wheels  10  are joinable between opposing side walls of the frame  9 , in accordance with conventional technologies. Each wheel  10  includes a centrally located hub  12  surrounded by an elastomeric tire  20 . An annular interlock flange  14 , preferably integrally formed with the hub  12 , protrudes about the perimeter of the hub  12 . The annular interlock flange  14  is oriented orthogonally to the axis of wheel rotation, and is centered in the width of the hub. An annular groove  16  is formed in a radial perimeter of the annular interlock flange  14 , and is dimensioned to seat a coil spring  18 , as shown in FIGS. 2 and 3. The width of the flange  14  increases adjacent to groove  16 . 
     The coil spring  18  extends around the annular interlock flange  14 , and is preferably tensioned (i.e. expanded) sufficiently such that there is a predetermined degree of some spacing between individual coils. The individual coils are positioned approximately perpendicular to the axis of wheel rotation. The coil spring  18  extends about the entire circumference of the groove  16 , and the ends of the coil spring  18  are joined, preferably by crimping or welding the ends together so that the spring is continuous. With the ends joined, the coil spring  18  forms a tubular ring that is concentric with the annular interlock flange  14  and the hub  12 , as can be seen in FIGS. 2 and 3. 
     A conventional elastomeric tire  20  is cast around the radial perimeter of the hub  12 , including the flange  14  and the coil spring  18 . The tire at least partially, and preferably completely, envelops the radial perimeter and the lateral sides of the windings of the coil spring  18 . The radial perimeter of the coil spring  18  is the area of the coil spring  18  opposite the interlock flange  14 . The lateral sides of the coil spring  18  includes the annular surfaces of the coil spring between the interlock flange  14  and the radial perimeter. The tire  20  is thus secured by the coil spring  18  and flange  14 . 
     The hub  12 , including the annular interlock flange  14 , can be formed from any of a variety of relatively rigid materials, such as metal or plastic. The coil spring  18  is formed from a semi-rigid, resilient material. The coil spring  18  may suitably be composed of piano wire. The sectional diameter of the coil spring  18  is less than the width of the hub  12  and tire  20 , and may suitably be approximately ¼ of the width of the hub and tire. While the spring  18  is resilient along its length, it is relatively rigid across its width, i.e., in the radial direction of the wheel  10 . The flange  14  and spring  18  cooperatively define a profile having a wide head and a narrow stem extending from the hub  12 . 
     In the preferred embodiment, the dimensions of the coil spring  18  and the tire  20  are such that the coil spring supports the tire  20  to reduce the deflection of the tire  20  by a predetermined amount. The reduced deflection decreases the surface area of the flattened contact zone between the tire  20  and the ground. Therefore, friction or rolling resistance is reduced, resulting in increased speed. Equally important, the dimensions of the coil spring  18  and the tire  20  are such that a sufficient amount of deflection is maintained to still provide for grip between the tire  20  and the ground. 
     More specifically, in the preferred embodiment, the distance between the radial perimeter of the tire  20  and the coil spring  18  is approximately equal to one-third of the thickness of the tire  20 . For example, the distance between the perimeter of the tire  20  and the coil spring  18  may be about three to four millimeters, while the total radial thickness of the tire  20  may be about ten millimeters. 
     Unlike conventional skate wheels in which the profile of the annular flange is narrow, the cross-sectional profile of the coil spring  18  approximates the profile of the tire  20 . The axial width of the coil spring  18  therefore more effectively supports the tire  20  to reduce deflection and thereby increase speed, while maintaining enough deflection to provide grip with the ground. At the same time, the distance between the coil spring  18  and the tire  20  is sufficient to provide for a comfortable and smooth skating experience. 
     Referring to FIGS. 4 and 5, an alternative embodiment of a skate wheel  22  is illustrated. In this alternative embodiment, an annular tube  24 , having a circular cross section, is cast as an integral part of the hub  12 , defining the radial extremity of the annular interlock flange  14 . The circular tube  24  runs around the annular perimeter of the annular interlock flange  14 . The circular tube  24 , the hub  12  and the interlock flange  14  are formed from any relatively rigid material, such as metal or plastic. The dimensions of the circular tube  24  in relation to the tire  20  are the same as the dimension of the spring  18  in the preferred embodiment. The tube  24  may include a plurality of apertures so that it is filled with the elastomer forming the tire  20  (as shown), or it may be hollow and unfilled, or solid throughout. 
     Referring to FIG. 6, another alternative embodiment of a skate wheel  26  is illustrated. In this embodiment, a number of radially spaced arcuate ribs  28  (or approximately semi-circular rings) are integrally formed with the hub  12  and annular interlock flange  14 . The ribs  28  protrude from the radial perimeter of the annular interlock flange  14  and are positioned in an alternating arrangement. That is, the free end of alternating ribs  28  points to the same side of the skate wheel  26 , with interposed ribs  28  pointing to the opposite side. The ribs  28  are formed from any relatively rigid material such as metal or plastic. However, the rigidity of the ribs  28  may be increased to support the tire  20  more effectively by injecting the ribs  28  with a glass-filled polymer, filling the spaces therebetween, prior to casting the tire  20 . 
     While the preferred embodiments of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.