Abstract:
The present invention provides a bicycle hub that is usable with a disc brake. The hub has a tubular body extending along a longitudinal axis between the ends thereof. One end of the hub is configured to mate with and retain a brake disc on a disc seat that has a predetermined configuration. Spaced from the disc seat along the longitudinal axis there is a fastener portion of the hub which is configured to receive a fastener that locks the disc on the hub. The disc seat and fastener portion are separated by section of the tubular body that does not form any part of either the disc seat or the fastener portion

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C.§119 to Italian Patent Application No. MI2006A002385. 
       BACKGROUND 
       [0002]    The present invention regards a hub usable in a bicycle wheel having a disc brake. 
         [0003]    In bicycle wheels with disc brakes, the brake disc is normally mounted so as to make the disc integral in rotation with the wheel. Known solutions to using disc brakes are flawed in that they either have limited mechanical resistance or they require a relatively thick hub that adds undesired weight or compelxity to the hub. 
         [0004]    The problem underlying the present solutions result in the art desiring a hub suitable for a disc brake hub that can be easily mounted without requiring technical solutions which weigh down the hub or complicate its manufacture. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention comprises a tubular body extended axially along a rotation axis of the wheel that includes a coupling profile for reception and locking in position a brake disc. The hub is further characterised by having the disc coupling profile and the locking portion physically separated from each other along the axis of the tubular body. Using this configuration means that the disc position and locking portion are independent from each other and can be chosen and sized in an optimal manner without mutual constraints. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0006]    Further characteristics and advantages of the invention will be evident from the following description of several embodiments thereof, made with reference to the attached drawings. In such drawings: 
           [0007]      FIG. 1  is a view along the longitudinal axis of a hub according to a first embodiment of the invention, with a partial section; 
           [0008]      FIG. 2  is a perspective view of the tubular body of a hub acording to a first embodiment of the invention; 
           [0009]      FIG. 3  is a side elevation of  FIG. 2  in the direction III; 
           [0010]      FIG. 4  is an enlarged view of the circled detail of  FIG. 3 ; 
           [0011]      FIG. 5  is a view along the longitudinal axis of a hub according to a second embodiment of the invention, with a partial section; 
           [0012]      FIG. 6  is a perspective view of the tubular body of a hub according to a second embodiment of the invention; 
           [0013]      FIG. 7  is a view along the longitudinal axis of a hub similar to the hub group of  FIG. 5 , assembled with a brake disc and a locking ring, and with a partial section; 
           [0014]      FIG. 8  is an exploded view of the assembly of  FIG. 7 ; 
           [0015]      FIG. 9  is a side elevation of a bicycle which incorporates hub asemblies according to the invention; 
           [0016]      FIG. 10  is an enlarged scale view of a portion of the hub group of  FIG. 1 . 
           [0017]      FIG. 11  an alternative form of the end the tubular body of present invention that is devoid of threads. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    As shown in  FIG. 9 , a bicycle  1  typically comprises a frame  2 , a front wheel  3  and a rear wheel  4 , each of which has spokes  5 , and, in this instance, each wheel is equipped with a disc brake assembly  6 . 
         [0019]    With reference in particular to  FIGS. 1-4 , a hub  10  according to the invention for use with the front wheel  3  of the bicycle  1  comprises a tubular body  11 , extended around a longitudinal axis X extending between the ends  12  and  13  corresponding with the rotational axis of the wheel  3   
         [0020]    The tubular body  11  is externally provided with two series of protuberances  14  and  15 , not illustrated in detail since they are not concerned with the embodiments of the present invention, for the coupling to the spokes  5 . Inside the tubular body  11 , a spindle  17  is supported by first and second rolling bearings, respectively  18  and  19 . The spindle  17  is of a known construction with right and left terminal portions  20  and  21 , firmly fixed to close the opposite ends of the spindle  17  and shaped so as to provide connection seats  22  and  23  to the frame  2  of the bicycle  1 . The bearing  18  is of a known one ball row type, while the bearing  19  is of a two ball row type with balls of lesser diameter than those of the bearing  18   
         [0021]    Two annular closing caps  24  and  25  are provided between the spindle  17  and the tubular body  11 , equipped with respective seals  26  and  27  towards the tubular body  11 . The first annular cap  24  (on the right in  FIGS. 1 and 2 ) is screwed on the spindle  17  while the second annular cap  25  is mounted or pressed on with force applied on the spindle  17  itself. 
         [0022]    It is noted that the mounting of the spindle  17  in the tubular body  11  provides that the left annular cap  25  goes in abutment—towards the left, with reference to FIG.  1 —against a projecting flange  29  of the left terminal portion  21  (in turn made integral with the spindle  17 , such as by gluing) and abutment—from the right—the inner race  19   a  of the second bearing  19 . The outer race  19   b  of the same left bearing  19  abutments against a shoulder  31  formed in the tubular body  11 ; the shoulder  31  therefore defines a housing seat of the left bearing  19  in the tubular body  11 . The right bearing  18  race  18   b  is in abutment against a shoulder  32  formed in the tubular body  11  and its inner race  18   a  is in abutment against the right annular cap  24 . It will be understood that the right annular cap  24 , which is screwed on the spindle  17 , serves to register the bearing coupling between the spindle  17  and the annular body  11 . The annular cap  24  is open ring shaped, and is tightened closed in the mounting on the spindle  17  by means of a transverse grub screw (only indicated schematically with  34 ), to prevent the loosening of the annular cap  24 . 
         [0023]    The tubular body  11  has a disc seat  40  for receiving and locking a brake disc (see element  280  in  FIG. 7 ). The disc seat  40  comprises an outer portion of the tubular body  11  shaped according to a predetermined coupling profile. With this term it is intended that the profile of the disc seat  40  has geometric characteristics such as to permit the transmission of a torsional movement between the tubular body  11  and the brake disc mounted on the seat with a matching profile. The predetermined profile can be for example a polygonal profile, or an altered circular profile (for example, levelled along a chord) or another profile. In the preferred embodiments, the coupling profile is a splined profile, with ribs  44  and grooves  45  oriented in a direction parallel to the X axis, see  FIG. 2 . The ribs  44  define a maximum diameter D c  of the splined profile, while the grooves  45  define a minimum diameter d f  of the splined profile. The shoulder  47  on body  11  provides an axial abutment position for a brake disc ( 280 ) mounted on the disc seat  40 . 
         [0024]    On the side of body  11  opposite the shoulder  47 , a thread  50  is formed for the coupling with a nut which holds the brake disc ( element  280  in  FIG. 7 ) on the disc seat  40 , preferably against the outer shoulder  47 . As can be seen from  FIG. 4 , the thread  50  extends over the outside of the tubular body  11  between a right end  52  and a left end  53  and has an outer diameter D e  and a core diameter d n . 
         [0025]    The disc seat  40  and the thread  50  are sized and separately positioned on the tubular body  11  so as to be axially separated by a intermediate portion of tubular body  11  or circumferential groove  60  that is part of neither of them. Thus, there exist a position along the longitudinal X axis in which only the disc seat  40  is present and positions in which only the thread  50  is present; there are no positions in which both the disc seat  40  and the thread  50  are present together or overlapping. 
         [0026]    The following conditions are present in the preferred embodiments:
       the thread  50  is closer than the disc seat  40  to the second end  13  of the tubular body  11 , i.e. the left end  53  of the thread  50  is closer than the left end  43  of the disc seat  40  to the left end  13  of the tubular body  11 ;   the crest diameter D c  is greater than the outer diameter D e ;   the bottom diameter d f  is greater than the core diameter d n ;   the bottom diameter d f  is greater than the outer diameter D e ;   the second end  43  of the disc seat  40  is located between the first end  52  of the thread  50  and the first end  12  of the tubular body  11 ;   the radial extension of the ribs  44  and grooves  45  between the bottom diameter d f  and the outer diameter D e  is comprised between 0.5 and 2 mm, and preferably between 0.5 and 1 mm.       
 
         [0033]    With respect to the predetermined coupling profile, it is preferred that the ribs  44  and grooves  45  have a trapezoidal shape which is symmetric with respect to a radial plane R (see  FIG. 4 ). The number of the ribs  44  is preferably between 10 and 60, more preferably between 20 and 60, and most preferably between 40 and 60. The number of the grooves  45  is of the same range as that selected for the ribs  44 . 
         [0034]    With reference in particular to  FIGS. 5 and 6 , a hub  110  for the rear wheel  4  of the bicycle  1  comprises a tubular body  111 , extended around a longitudinal axis Y which is parallel to the longitudinal axis X. Except as described below, the hub  110  is as described with respect to hub  10  similar elements have similar numbers plus 100. 
         [0035]    Unlike the hub  10 , the hub  110  comprises a pinion-carrier group  170 , rotatably mounted on the spindle  117  by means of rolling bearings  171  and  172 , and coupled to the tubular body  111  by means of a freewheel connection  173 , close to the first end  112  thereof. The pinion-carrier group  170  is of know construction and will not be described in detail below. 
         [0036]    An annular closure cap  125  is then provided between the spindle  117  and the tubular body  111 , equipped with a seal  127  towards the tubular body  111 . The annular cap  125  is screwed on the spindle  117 . 
         [0037]    It is noted that the mounting of the spindle  117  in the tubular body  111  provides that the inner race  118   a  of the right bearing  118  goes in abutment—towards the right, with reference to FIG.  5 —against a shoulder  129  formed on the spindle  117 , while the outer race  118   b  of the same right bearing  118  receives a shoulder  132  in abutment, formed in the tubular body  111 ; the shoulder  132  therefore defines a housing seat of the right bearing  118  in the tubular body  111 . The left bearing instead has its outer race  119   b  in abutment—towards the right—against a shoulder  131  formed in the tubular body  111  and its inner race  119   a  in abutment—towards the left—against the annular cap  125 ; the shoulder  131  therefore defines a housing seat of the left bearing  119  in tubular body  111 . In this manner, it is understood that the annular cap  125 , which—as said—is screwed on the pin  117 , serves as register element of the bearing coupling between the spindle  117  and the annular body  111 . The annular cap  125  is open ring shaped and in the mounting is tightened closed on the spindle  117  by means of a transverse grub screw (indicated only schematically with  134 ), in order to prevent the loosening of the annular cap  125 . 
         [0038]    A disc seat  140  is provided outside the tubular body  111  for reception and locking in rotation of a brake disc (not shown in  FIGS. 5 and 6 ). The disc seat  140  comprises an outer portion of the tubular body  111  comprised between a first right end  142  and a second left end  143 , shaped according to a form coupling profile, equal to that of the disc seat  40  of the hub  10 . In particular, the form coupling profile of the disc seat  140  of the hub group  110  is a splined profile, with ribs  144  and grooves  145 , oriented in a direction parallel to the Y axis. The ribs  144  define a maximum crest diameter D c  of the splined profile, while the grooves  145  define a minimum bottom diameter of the splined profile. 
         [0039]    Close to the disc seat  140 , in proximity to its right end  141 , the tubular body  111  comprises an outer shoulder  147  which provides an axial abutment position for a brake disc mounted on the disc seat  140 . 
         [0040]    Still close to the disc seat  140 , near its left end  143 , a thread  150  is provided formed on an outer portion of the tubular body  111 , for the coupling with a threaded ring nut (not shown in  FIGS. 5 and 6 ) which holds a brake disc (it too not shown in  FIGS. 5 and 6 ) on the disc seat  140  against the outer shoulder  147 . The thread  150 , equivalent to the thread  50  of the hub  10 , extends along the outside of the tubular body  111  between a right end  152  and a left end  153  and has an outer diameter D e  and a core diameter d n . 
         [0041]    The disc seat  140  and the thread  150  are sized and positioned on the tubular body  111  so as to be axially separate, in the sense specified above. More in particular, the following relations are valid in the hub  110 :
       the thread  150  is closer than the disc seat  140  to the second end  113  of the tubular body  111 , i.e. the left end  153  of the thread  150  is closer than the left end  143  of the disc seat  140  to the left end  113  of the tubular body  111 ;   the crest diameter D c  is greater than the outer diameter D e ;   the bottom diameter d f  is greater than the core diameter d n ;   the bottom diameter d f  is greater than the outer diameter D e ;   the second end  143  of the disc seat  140  is located at the first end  152  of the thread  150 , i.e. the disc seat  140  and the thread  150  are adjacent along the Y axis.       
 
         [0047]    One or more holes  154  are made in the thread  150  for the access to the locking grub screw  134  of the annular cap  125 . 
         [0048]    With reference in particular to  FIGS. 7 and 8 , a hub  210  is shown for the rear wheel  4  of the bicycle  1 , substantially equal to the hub  110 , except for insignificant details of elements extraneous to the present invention, such as the pinion carrier group  270  and the annular cap  225 . Therefore, this hub  210  will not be described in detail; its elements, equivalent to the hub  110 , are marked by the same reference numbers plus  100 . 
         [0049]    The hub  210  also comprises a brake disc  280  and a threaded ring nut  290 . The brake disc  280  comprises a peripheral disc portion  281  which is firmly fixed to a central mounting ring  282 ; a central hole  284  is made in the mounting ring  282 , provided with a splined profile matching the splined profile of the disc seat  240 . The brake disc  280  is mounted with the mounting ring  282  on the disc seat  240 , locked in rotation by the coupling between the splined profiles of the disc seat  240  and the central hole  284 . The ring nut  290  pushes the brake disc  280  against the outer shoulder  247 , thus ensuring that the brake disc  280  remains in engagement on the disc seat  240 . 
         [0050]    In  FIG. 10 , the second bearing  19  of the hub  10  is illustrated in greater detail; the bearings  119  and  219  of the hubs  110  and  210  are equivalent to the bearing  19 , and thus that illustrated in  FIG. 10  and described below also holds for the bearings  119  and  219 . 
         [0051]    As already stated, the bearing  19  has two ball rows, a first row  91  closer to the first end  12  of the tubular body  11  and a second row  92  closer to the second end  13  of the tubular body  11 . The first ball row  91  runs along a first inner runway  93  made on the inner race  19   a  and on a first outer runway  94  made on the outer race  19   b ; the second ball row  92  runs along a second inner runway  95  made on the inner race  19   a  and a second outer runway  96  made on the outer race  19   b.    
         [0052]    The runways  93 - 96  have rounded, particularly semicircular section; the first outer runway  94  is wider than the other runways  93 ,  95  and  96 , in particular it has a radius section R 2  greater than the radius R 1  of the other runways. 
         [0053]    In this manner, the first ball row  91  substantially supports only radial loads and not also axial loads, which are left to the second ball row  92 . This ensures a greater slidability of the bearing  19 . The fact that the radial load is left to the second row  91 , closer to the second end  13  of the tubular body  11 , ensures a greater stiffness to the set. The choice, then, of having the runway  94  wider on the outer race  19   b  rather than on the inner race  19   a  is due to the consideration that a wider runway reduces the contact area of the balls of the runway, thus increasing the specific pressure; this phenomenon—potentially a source of problems—is more easily acceptable on the outer race  19   b , which has a greater circumferential extension than the inner race  19   a  and therefore lower specific pressures. 
         [0054]      FIG. 11  shows an alternative embodiment  311  of the tubular body that differs from the tubular body of  FIGS. 1-4  because its axially outermost portion  395  of the second end  313  is not threaded. In this way the beginning of the thread  350  is preserved from being damaged by lateral shocks. In the illustrated embodiment the axially outermost portion  395  has an outer diameter Do that is lower or equal to the core diameter d n  of the thread  350 . Between the thread  350  and the disc seat  340  is interposed a smooth portion  360  which can have the same outer diameter D e  e of the thread  350 , as in  FIG. 11 , or can be a groove. 
         [0055]    It is known that, in a hub according to the invention, such as the hubs  10 ,  110  and  210 , the disc seat  40 ,  140 ,  240  does not interfere with the thread  50 ,  150 ,  250 , improving the mechanical stress conditions in the material of the tubular body  11 ,  111 ,  211 , which can therefore be designed with a relatively very small thickness. 
         [0056]    Moreover, due to the axially separate position of the thread  50 ,  150 ,  250  with respect to the disc seat  40 ,  140 ,  240 , the radial size is much reduced, such that—by possibly employing a reduced left bearing  19 ,  119 ,  219 , for example with double ball row—it is possible to keep the diameter of the brake disc  40 ,  140 ,  240  very small, and thus keep that of the tubular body  11 ,  111 ,  211  very small, equivalent to that of a tubular body of a hub for a wheel that does not have a disc brake. 
         [0057]    Finally, the presence of the second bearing  19 ,  119 ,  219  inside the tubular body  11 ,  111 ,  211  at the disc seat  40 ,  140 ,  240  contributes to considerably stiffening the tubular body itself, precisely where the braking torque is applied, permitting risk-free mounting even of brake discs  280  with large diameters and great breaking power, such as those typical of so-called downhill bicycles, without requiring an excessive diameter of the tubular body  11 ,  111 ,  211 .