Abstract:
An improved wheel rim, an improved spoke nipple and an improved wheel are disclosed. The rim has spoke openings and a threaded end of each spoke extends therethrough. An internal nipple with a threaded bore is connected to the threaded spoke end so that a first, ball-shaped, rounded end of the nipple is seated on the rim. A portion of the rim around each spoke opening is deformed or removed so as to define a portion of a socket with the same curvature as the first end of the nipple. This minimizes the required diameter of the spoke opening in the rim and maximizes the area of the rim socket surface. The invention also extends to an external nipple with a rounded collar in combination with a rim including a concave rounded rim surface formed in the rim itself.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to wheels for human powered vehicles such as bicycles, wheel chairs and the like, and especially to a novel wheel with a unique rim and unique spoke nipples.  
           [0003]    2. Description of the Prior Art  
           [0004]    Spokes and rims for wheels for human powered vehicles have been the subject of numerous innovations over the years.  
           [0005]    U.S. Pat. No. 2,937,905 (Altenburger) discloses a tubeless tire rim and a way to connect spokes to it.  
           [0006]    U.S. Pat. No. 5,769,584 (Claes), the disclosure of which is incorporated herein by reference, discloses a nut for a spoke in a bicycle wheel. The nut has an enlarged head with a rounded collar, which permits the nut to align itself in a spoke hole of the rim when a spoke connected in the nut is put into tension by the nut. The nut or nipple is what is commonly referred to as an external nipple, which means that a portion of the nipple extends through the spoke hole in the rim and is accessible outside of the rim cavity. That external portion of the nipple has four flats that cooperate, in a known manner, with a nut spanner for rotating the nut externally, i.e., outside, of the rim.  
           [0007]    The structure disclosed in Claes includes a lining or eyelet  13 , which is seated in each spoke bore in the rim of the wheel. Each lining or eyelet has an upper flange that rests on an upper surface of the rim bottom, a cylindrical side wall, which extends downwardly from the upper flange and through the spoke opening in the rim and a lower flange which rests on a lower surface of the rim. The patent appears to be silent about how such an insert or eyelet is secured to the rim, but clearly it involves an upset operation to seat the eyelet in the rim within the spoke opening. The insert defines a ring on which the rounded collar is supported. Due to the external portion of the spoke nut extending through the spoke hole or opening in the rim, and through the spoke hole or opening in the eyelet or insert, and the clearance required for the spoke and the external portion of the nut to pivot to the degree required to accommodate what is defined hereinafter as the centering angle and the torsional angle, the spoke hole or opening is, necessarily, many times larger than the diameter of the spoke itself. As a consequence, the surface on which the rounded collar rests is relatively small because of the large opening required to accommodate the spoke and the external portion of the nipple.  
           [0008]    European Published patent application no. EP 0 714 791 discloses an external nipple with a rounded collar which rests on an insert called a guide. Swiss Patent No. 355041 discloses an external nipple with a rounded collar that rests on an insert in the rim. French Patent No. 1,498,599 discloses an external nipple with a conical collar that rests on an insert in the rim. French Patent No. 1,516,857 discloses a rim insert for supporting an external spoke nipple. German Patentschrift No. 583 902 discloses a rim insert for supporting an external spoke nipple. European Published patent application no. EP 0 860 301 discloses an external nipple with a rounded collar and a rounded insert for supporting the nipple on the rim.  
           [0009]    Bicycle wheel makers have long struggled with the problems that arise due to the fact that the spokes in a bicycle wheel do not extend radially from the hub to the rim. In other words, the spokes are skewed relative to a true radius. This is illustrated in FIGS. 1 and 2 hereof, which are based upon FIGS. 2 and 1, respectively, of U.S. Pat. No. 4,583,787 (“Michelotti”), the disclosure of which is incorporated herein by reference.  
           [0010]    [0010]FIG. 1 illustrates what I call the centering angle of a spoke, in the context of a rim  10  that has a radius R. In the drawing, the radius R coincides with the center plane of a wheel including the rim  10 , the center plane being perpendicular to the axis of rotation of the wheel and intersecting the center line of the rim. The longitudinal axis, designated SA, of a spoke (not shown) attached to a left hub flange (not shown) deviates from the rim radius R by an angle designated CA for centering angle. In the drawing, the spoke axis SA intersects the rim radius R outside of the rim  10 . Because of this deviation, a spoke connected to the rim  10  and a left hub flange (not shown) exerts a lateral force which is balanced, more or less, depending on the spoking pattern, by an opposite lateral force exerted by one or more spokes (not shown) connecting the rim  10  to a right hub flange (not shown). These lateral forces keep the rim centered in the wheel center plane and provide essential lateral stability to radially spoked wheels and to tangentially spoked wheels. Thus, the name centering angle.  
           [0011]    [0011]FIG. 2 illustrates what I call the torsional angle of a spoke, in the context of a rim  10  that has a radius R. In the drawing, the radius R coincides with the center plane of a wheel including the rim  10 , the center plane being perpendicular to the axis of rotation of the wheel and intersecting the center line of the rim  12 . The longitudinal axis, designated SA, of a spoke  14  attached to a right or left hub flange (not shown) deviates from the rim radius R by an angle designated TA for torsional angle. Because of this deviation, which is found in tangentially spoked wheels, primarily used as rear driving wheels, the spoke  14  is operable to transmit a pulling or torsional force from a rotating hub to the rim  12 , tending to cause the rim to rotate. Thus, the name torsional angle. Generally speaking, there is no torsional angle in wheels that are radially spoked. Generally speaking, a spoke that has a torsional angle also has a centering angle.  
           [0012]    Michelotti discloses eyelets or inserts which are intended to support the spoke nut or nipple in a skewed position, corresponding as required to the centering angle or the centering and torsional angle, as necessary. This approach does not and cannot account for dynamic displacements and distortions of a spoke under dynamic conditions. Further, the use of eyelets or inserts, as noted above, is labor intensive. In the case of Michelotti&#39;s eyelets, however, exact positioning and orientation of the eyelets is required to support each spoke, as intended.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is based upon the discovery of an improved wheel rim, an improved spoke nipple and an improved wheel including that rim and nipple. The rim has a lower section in which spokes are connected. A first, threaded end of each spoke extends through a spoke opening and into a cavity in the rim. A nipple with an internally threaded bore is connected to the threaded end of the spoke so that a first end of the nipple is seated on the floor of the rim and a second, opposed end is within the rim cavity. In other words, the nipple is located entirely within the rim cavity. According to the invention, that first end of the nipple has the shape of a portion of a sphere or ball and a portion of the rim floor is deformed or removed so as to define a portion of a socket so that the interior surface of the socket formed in the rim has the same curvature as the exterior ball-shaped surface of the first end of the nipple. This construction permits the end of the spoke and the nipple to align themselves, and to realign themselves, with the spoke, as needed, to prevent lateral forces from being imposed on the spoke, even under dynamic conditions when the spoke is tensioned and de-tensioned. Because the nipple is carried entirely within the rim cavity, only the spoke extends through a spoke opening in the rim, thereby minimizing the required diameter of the spoke opening in the rim and maximizing the area of the rim surface on which the rounded end of the internal nipple rests. The invention also extends to the case of an external nipple with a rounded collar, as disclosed in the Claes patent, in combination with a rim including a concave rounded rim surface formed in the rim itself, around a minimal diameter spoke opening so that there is more surface area on the rim, around the spoke opening, to support the external nipple than in prior art structures including a rim insert.  
           [0014]    Accordingly, it is an object of the present invention to provide an improved rim with a socket formed integrally therein around each spoke opening to cooperate with a spherical portion of a first end of a nipple connected to the spoke.  
           [0015]    It is a further object of the invention to provide an improved spoke nipple including a rounded portion at a lower end of the nipple, which cooperates with the socket shaped portion of the rim.  
           [0016]    It is a further object of the present invention to provide a wheel incorporating the novel spoke, nipple and rim connection described herein.  
           [0017]    It is yet another object of the present invention to provide a wheel in which the nipple and the end of a spoke connected therein orient themselves along the axis of the major portion of the spoke, to reduce stresses that would otherwise be imposed on the spoke.  
           [0018]    These and other objects and advantages of rims, spoke nipples and wheels according to the present invention will be fully appreciated by those skilled in the art upon reviewing the disclosures herein. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0019]    [0019]FIG. 1 is a modified version of FIG. 2 of the Michelotti patent, illustrating the centering angle of a spoke.  
         [0020]    [0020]FIG. 2 is a modified version of FIG. 1 of the Michelotti patent, illustrating the torsional angle of a spoke.  
         [0021]    [0021]FIG. 3 is a cross-sectional view through a portion of a rim according to a first embodiment of the present invention.  
         [0022]    [0022]FIG. 4 is a cross-sectional view through a portion of a rim according to a second embodiment of the present invention.  
         [0023]    [0023]FIG. 5 is a side view of a spoke nipple according to the present invention.  
         [0024]    [0024]FIG. 6 is a view, partially in cross-section and similar to FIG. 3, of a rim showing a spoke and nut connection according to the present invention.  
         [0025]    [0025]FIG. 7 is a view, partially in cross-section and similar to FIG. 4, of a rim showing a spoke and nut connection according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Referring to FIG. 3, a rim according to the present invention is indicated generally at  100  and comprises a left side wall  102  and a right sidewall  104 . A bottom portion of the rim  106  extends between the side walls  102  and  104 . A wall  108  of a spoke bore defines a spoke opening through the bottom portion  106  of the rim  100 . The bottom portion  106  of the rim  100  has been upset adjacent to the wall  108  of the spoke bore. Specifically, a tool T with a head H, including a spherical surface S, has been forced against the bottom portion  106  of the rim  100  to deform it to produce a concave, spherical surface  120  on the interior of the rim  100 . The act of upsetting the bottom portion  106  of the rim  100  is facilitated by the use of an anvil A. A cavity C is formed in a working surface of the anvil A. The anvil A is positioned against the outside surface of the bottom portion  106  of the rim  100 , with the cavity C aligned with and centered around the wall  108  of the spoke bore and the tool T is inserted into the rim  100  and aligned with the cavity C and the wall  108  of the spoke bore. The tool T is struck with enough force to upset the rim  100 , adjacent to the wall  108  of the spoke bore, to produce the concave, spherical surface  120 .  
         [0027]    Referring now to FIG. 4, a rim  140  according to the present invention comprises side walls  142  and  144  and a bottom portion  146 . A concave spherical surface  148  is formed on the interior surface of the bottom portion  146  of the rim  140 . A cutting tool CT with a spherical cutter head CH is used to form the surface  148 . A small amount of material is removed from the interior side of the bottom portion  146  of the rim  140 , around a wall  150 , which defines a spoke opening.  
         [0028]    Referring now to FIG. 5, a spoke nipple according to the present invention is indicated generally at  170 . The nipple  170  has a plurality of flats  172  so that torque can be applied to it by a suitable tool, such as a wrench (not shown). The nipple  170  is provided with an internally threaded longitudinally extending bore, indicated at  174 , for engaging external threads provided on the end of a spoke (not shown in FIG. 5). A lower end  176  of the nipple  170  terminates in a convex, rounded surface  178 . It is this rounded, convex surface that seats inside the rim  100  (FIG. 3) on the rounded, concave surface  120 , or inside the rim  140  (FIG. 4) on the rounded, concave surface  148 . It is preferred that the curvature of the surface  178  be the same as the curvature of the surface  120  or the surface  148 .  
         [0029]    Referring now to FIG. 6, a spoke  200  and a nipple  202  are shown connected to a rim  204 . The nipple  202  corresponds with the nipple  170  (FIG. 5) and the rim  204  corresponds with the rim  100  (FIG. 3). In this embodiment, the nipple  202  has a convex curved surface  206 , which is seated on a concave curved surface  208  formed in the rim. Thus, the nipple  202  can pivot relative to the rim  204 . As tension in the spoke  200  increases, as by rotation of the nipple  202 , the nipple  202  will align itself with the longitudinal axis of the spoke  200 , which is determined by the location of the connection of the other end (not shown) of the spoke  200  to a hub (not shown). Typically, this will involve a centering angle and, in the case of torque transmitting wheels, a torsional angle. Excellent results have been achieved in a case where the curved surface  206  and the curved surface  208  are spherical and have a curvature corresponding with a radius of 5 millimeters or a diameter of 10 millimeters.  
         [0030]    A cylindrically shaped wall  210  defines a spoke hole in the rim  204 . A rim portion  212  of the spoke  200  is adjacent to the wall  210 . It will be appreciated that the rim portion  212  of the spoke  200  may be threaded, like the portion (not shown) of the spoke  200  that is inside of the nut  202 , or it may be unthreaded. In the case where the nipple  202  is relatively short, the internal threads  174  (FIG. 5) will extend pretty much the length of the nipple, and the rim portion  212  (FIG. 6) of the spoke  200  will likely be threaded, as well, with the spoke threads (not shown) terminating below the rim  204  in FIG. 6. In the case of a relatively long nipple  202 , it is possible to counterbore the nipple  202 , adjacent to the rounded surface  206  so that all of the spoke threads are within the nipple  202  and the spoke portion  212  is unthreaded. According to the preferred embodiment of the invention, excellent results have been achieved where the diameter of the cylindrically shaped wall  210 , i.e., the diameter of the spoke hole, is approximately 0.141 inch in a case where the major diameter of the threaded rim portion  212  of the spoke  200  is about 0.090 inch. This provides enough clearance between the spoke  200  and the wall  210  to permit the spoke  200  to be skewed, according to the centering angle or the combination of the centering angle and the torsional angle, as the spoke  200  passes through the spoke bore in the rim  204 . In any case, according to the present invention, the diameter of the spoke hole through the rim must be greater than the diameter of the portion of the spoke, which extends through the spoke hole. However, the diameter of the spoke hole should be kept as small as possible, to maximize the area of contact between the curved surfaces  206  and  208 , while still providing the clearance required for the spoke to pivot. Preferably, the diameter of the spoke opening is about 1.5 times the diameter, or the major diameter, of the rim portion of the spoke extending therethrough. In the example given above, the ratio is a little less than 1.6 to 1.0. Preferably, the diameter of the spoke opening in the rim is 2.0 times or less than the diameter of the rim portion of the spoke. More preferably, the diameter of the spoke opening in the rim is 1.8 times or less than the diameter of the rim portion of the spoke. Even more preferred is the case where the diameter of the spoke opening in the rim is 1.6 times or less than the diameter of the rim portion of the spoke.  
         [0031]    It is noted that the spoke bore defined by the wall  210  extends radially, and that it is centered between the side walls of the rim  204 . This is preferred because it is very easy to machine. Other spoke bore orientations are within the scope of the present invention, however. In a case where the axes of the spoke bores are oriented so that they are aligned with the axes of the spokes, taking into account the centering angle and the torsional angle, if present, the diameter of the spoke opening in the rim can be 1.4 times or less than diameter of the rim portion of the spoke extending therethrough, or, even more preferably, 1.2 times or less than the diameter of the rim portion of the spoke. However, the present invention eliminates the need, apparently felt by some wheel builders, to drill spoke holes off of the center plane of the wheel/rim, in a vain effort to align the axis of the spoke hole with the centering angle or the centering angle and the torsional angle of the spoke. The effort is in vain, especially in the case of rear or torque transmitting wheels, because dynamic forces will cause movement of the spokes that can&#39;t be accounted for in static spoke connections. However, with a rim and spoke nipple according to the invention, such movement can be accommodated in the case where the spoke openings in the rim are aligned, more or less, with the axes of the spokes extending through them.  
         [0032]    Referring now to FIG. 7, a spoke  250  and a nipple  252  are shown connected to a rim  254 . The nipple  252  corresponds with the nipple  170  (FIG. 5) and the rim  254  corresponds with the rim  140  (FIG. 4). In this embodiment, the nipple  252  has a convex curved surface  256 , which is seated on a concave curved surface  258  formed in the rim, according to the method described above with reference to FIG. 4. Thus, the nipple  252  can pivot relative to the rim  254 . As tension in the spoke  250  increases, as by rotation of the nipple  252 , the nipple  252  will align itself with the longitudinal axis of the spoke. Excellent results have been achieved in a case where the curved surface  256  and the curved surface  258  are spherical and have a curvature corresponding with a radius of 5 millimeters or a diameter of 10 millimeters.  
         [0033]    A cylindrically shaped wall  260  defines a spoke hole in the rim  254 . A rim portion  262  of the spoke  250  is adjacent to the wall  260 . According to a preferred embodiment of the invention, the diameter of the cylindrically shaped wall, i.e., the diameter of the spoke hole is approximately 0.141 inch in the case where the major diameter of the threaded rim portion  262  of the spoke  250  is about 0.090 inch. This provides the clearance between the spoke rim portion  262  and the wall  260  that is needed to permit the spoke  250  to be skewed, according to the centering angle or the combination of the centering angle and the torsional angle, as the spoke  250  passes through the spoke bore in the rim  254 . In any case according to the present invention, the diameter of the spoke hole through the rim must be greater than the diameter of the portion of the spoke, which extends through the spoke hole. However, the diameter of the spoke hole should be kept as small as possible, to maximize the area of contact between the curved surfaces  256  and  258 , while still providing the clearance required for the nipple and spoke to pivot. It is noted that the spoke bore defined by the wall  260  extends radially, and that it is centered between the side walls of the rim  264 . This is preferred, for the reasons set forth above.  
         [0034]    In the case of a wheel according to the present invention including external nipples as described in the Claes patent, the rounded portion of the collar will be seated directly on a curved surface formed in the rim itself. Because the nipple isn&#39;t elevated off of the bottom portion of the rim, as in the case where an insert or eyelet is used as explicitly taught in the Claes patent, the degree of clearance required in the spoke opening in the rim is minimized compared to the prior art. This maximizes the surface area of the rim bottom that actually supports the nipple, thereby producing a stronger spoke connection to the rim. The relationships described above, between the diameters of the spoke holes in the rim and the diameters of the rim portions of the spokes, applies equally to the diameters of the spoke openings and the outer diameter of the portion of an external nipple extending through the rim. The relationships described above between the diameters of spoke holes oriented to align with the axes of spokes extending through them and the diameters of the spokes extending through them, applies equally to the relationships between the diameters of the spoke openings and the outer diameters of the portion of an external nipple extending through the rim.  
         [0035]    It will be appreciated that the nipple and rim construction set forth above not only accommodates the centering angle, as illustrated in FIGS. 6 and 7, but also accommodates the torsional angle, as well.