Abstract:
A hub, in particular for bicycles having a hub shell and two bearings received therein on bearing seats for rotatably supporting relative to a through axle, wherein the two bearings are retained at a defined axial distance by means of a sleeve. A radial spacer device is provided to reduce radial play of the sleeve in the hub shell and to facilitate inserting the through axle.

Description:
BACKGROUND 
     The present invention relates to a hub, in particular also for bicycles. The hub according to the invention is in particular suitable to be employed in a front wheel hub equipped with a through axle. 
     Hubs have become known in the prior art and in particular hubs for front wheels comprising through axles. These hubs comprise a hub shell at each end of which a bearing is received in a bearing seat. To retain the inner bearing rings at a defined distance, a sleeve is positioned between the inner bearing rings to retain the inner bearing rings at a defined axial distance from one another. 
     During mounting, the through axle is inserted through the inner bearing ring on one face of the hub. Thereafter the through axle must be passed through the sleeve which serves as a spacer between the bearings. The sleeve is configured with the thinnest feasible wall to save unnecessary weight. This is why the sleeve, which in a non-mounted state tends to be loosely arranged, rests on what is currently the radial bottom of the internal hub shell wall. This is why the through axle cannot be readily inserted into the sleeve because in this state the sleeve is not centered, the upper sleeve wall impeding insertion of the through axle. 
     To allow inserting the through axle into the sleeve, the user must therefore insert his finger or a tool into the hub from the other side, centering the sleeve in the hub shell such that the through axle can be inserted into the sleeve through the centrally disposed opening. 
     In particular since the entire front wheel must often be conveniently aligned relative to the dropouts of the front wheel fork, such sleeve alignment is a awkward additional action, unnecessarily time-demanding and often involving a number of attempts or a suitable tool. 
     One solution to this problem may be, to dispense with a through axle, employing instead a so-called hollow axle on which the bearings are arranged and through which a quick release or the like is passed for fastening the hub and the wheel to the fork. 
     These wheels with hollow axles operate reliably and have been used for a long time. In particular in mountain-biking, however, high or extremely high lateral loads as well as torsional loads on the wheel tend to occur. This is why a particularly high rigidity of the wheel is desired. For this purpose, through axles generally offer the advantage of a higher lateral rigidity. 
     Against the described background of the prior art it is therefore the object of the present invention to provide a hub, in particular for a bicycle, which allows greater ease of mounting while employing a through axle. 
     SUMMARY 
     The hub according to the invention is in particular provided to be employed in bicycles and the inventive hub serves particularly preferably as a front wheel hub. The hub comprises a hub shell and at least two bearings received therein on bearing seats to rotatably support the hub shell relative to a through axle. The two bearings are axially spaced apart from one another by means of a sleeve. At least one radial spacer device is provided to reduce the radial play of the sleeve in the hub shell and to facilitate inserting the through axle. 
     The hub according to the invention has many advantages. It is one considerable advantage of the inventive hub that employing a through axle ensures high rigidity of the hub, while on the other hand allowing ease of mounting by way of the at least one spacer device. The radial spacer device considerably reduces the radial play of the sleeve relative to the hub shell such that when not mounted, the through axle can be passed through a bearing and inserted into the sleeve with minor effort. 
     At the same time the overall weight which is significant in the field of bicycle hubs is virtually not increased since the radial spacer device can be configured very lightweight. The radial spacer device serves to facilitate inserting the through axle through the sleeve. It does not serve for transmitting any radial or axial forces so as to allow lightweight materials, thin walls, and thus a low weight of the spacer device. 
     Advantageously the spacer device is arranged so as to allow a non-contact rotation of the hub shell around the sleeve in operation. Since the sleeve serves to keep the inner bearing rings axially spaced apart from one another, the sleeve is stationary in operation as is the through axle, while the hub shell rotates about the stationary through axle and the sleeve. A rubbing contact would result in abrasion long-term, impairing the hub function. 
     By way of the radial spacer device, defined conditions are set which considerably facilitate inserting the through axle. 
     The radial play between the sleeve and the hub shell is reduced by way of one, two, or several radial spacer devices so as to allow easy insertion of the through axle. 
     In a preferred specific embodiment the sleeve is configured as a substantially tubular, hollow body. The sleeve is in particular configured with thin walls to not unnecessarily increase the total hub weight. 
     In a preferred specific embodiment at least one spacer device is positioned at the sleeve. Preferably at least one radial spacer device is positioned on the radial outside of the sleeve. The spacer device may for example be configured as a separate component which is mounted on the outside of the sleeve e.g. during mounting. 
     Or else it is conceivable to configure the spacer device integrally with the sleeve such that the spacer device, being part of the sleeve, radially protrudes from the sleeve body in one defined or in several defined points to reduce radial play. 
     Preferably the spacer device is configured as a separate component. The spacer device may for example be configured as a ring or a disk, being slipped over the sleeve in the axial direction to serve as a spacer and when the hub is not mounted to a fork, to facilitate inserting the through axle during mounting. 
     Preferably the spacer device comprises at least one annular body which may in particular consist of a flexible material. It is particularly preferred for the annular body to consist of a lightweight material, rubber, plastic, felt, or the like. Annular bodies of these materials are low in weight while fulfilling the desired function. Or else it is conceivable for a ring of a light metal or the like to be provided on the sleeve. 
     To ensure durable function even in the case of repeatedly mounting and demounting, the annular body may be guided in a groove on the outside of the sleeve or the inside of the hub shell so as to reliably prevent axial displacement of the annular body. 
     To arrange the spacer device on the sleeve as a separate component offers advantages over integral manufacture since machining is much simpler. The sleeve does not require to be machined so as to leave a radial spacer device remaining but a separate spacer device may be slipped onto the sleeve or inserted into the hub shell. Machining one or two grooves on the sleeve is much simpler than machining the sleeve so as to have a radial spacer device remaining. 
     In all of the configurations it is conceivable for the spacer device or the at least one spacer device to be positioned on and/or attached to the hub shell. For example a spacer device may be positioned on the radially inner peripheral surface of the hub shell, being configured as a disk having a corresponding through hole, or as a ring. 
     It is preferred for all of the configurations that at least one spacer device is configured as an O-ring which is in particular placed in an outside groove on the sleeve, or inserted in an inside groove of the hub shell. 
     It is particularly preferred for the spacer device to be provided on the sleeve since such a configuration allows easy retrofitting of existing hubs. A simple replacement of an axial spacer sleeve by the sleeve equipped with a radial spacer allows to considerably facilitate the mounting of existing hubs. 
     Advantageously the hub comprises a through axle which is supplied with the hub and in particular comprises a chamfered edge on one insertion end to facilitate inserting. In particular, a radial extension of the spacer device, an inner or smaller diameter of the chamfered edge, and an internal diameter of the sleeve are matched to one another such that the insertion end can be inserted into the sleeve lying inside the hub shell. 
     A radial extension of the spacer device is preferably dimensioned such that the chamfered edge of the insertion end can be inserted into the sleeve which lies in the hub shell. 
     Preferably an adapter ring is provided at least on one axial face of the hub shell. It is particularly preferred that an adapter ring is provided on each of the two axial end faces of the hub shell and inserted in the hub shell with one portion and bearing against the inner bearing ring and supporting the inner bearing ring in the axial direction. 
     The adapter rings are in particular axially inserted in the hub shell so as to allow particular ease of demounting. 
     It has been found that in demounting a wheel the axial adapter rings can fall out of the hub shell as the through axle is removed. This is in particular intensified because the adapter ring must have a certain radial play relative to the hub shell to avoid that the stationary adapter ring comes into rubbing contact with the rotating hub shell. 
     In preferred more specific embodiments each adapter ring is preferably provided with a retaining means to retain the adapter ring to the hub shell even after removing the through axle. 
     Preferably the retaining means consists of a light metal or of plastic, being in particular annular in shape. It is particularly preferred for at least one retaining means to be pressed or screwed into one axial face of the hub shell. Such a retaining means reduces the clear diameter at the end of the hub shell such that the adapter ring can no longer be pulled out through the remaining opening. In this way the adapter ring is secured to the hub shell. At the same time the dimensions of the retaining means and of the adapter ring are chosen so as to allow no-contact operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantageous applications and features of the present invention ensue from the exemplary embodiments which will now be described with reference to the Figures. 
       The figures show in: 
         FIG. 1  a perspective, exploded view of a front wheel hub on a bicycle fork; 
         FIG. 2  a sectional view of the front wheel hub according to  FIG. 1 ; 
         FIG. 3  a sectional view of another hub according to the invention; and 
         FIG. 4  a schematic illustration of the insertion procedure for a through axle into a hub according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the  FIGS. 1 to 4 , two exemplary embodiments of the present invention will now be described. 
     The hub  1  according to the invention is in particular configured as a front wheel hub and may be employed in a suspension fork  100 . The suspension fork  100  illustrated in  FIG. 1  only in part and schematically in an exploded view comprises stationary tubes  43  and  44  with bottom dropouts  22  where bushings  20  and  21  are inserted into the stationary tubes  43  and  44 . 
     To mount the hub  1  to the suspension fork  100 , a wheel—not shown—is held with its hub  1  between the bushings  20  and  21  and the through axle  5  is inserted with its insertion end  14  through the bushing  20  into the hub shell  2  of the hub  1  and screw-fastened by means of the quick release lever  25  so as to result in a secure seat of the hub  1  or the wheel in the front wheel fork  100 . The knurled disk  31  contributes to securing the connection. 
     The hub  1  from  FIG. 1  is illustrated in  FIG. 2  in section. As is typical for these hubs  1  provided for through axles  5 , the hub  1  comprises an inner sleeve  6  which serves as an axial spacer for the pair of bearings  4   a  and  4   b . In the absence of such an axial spacer in the form of a sleeve  6 , the inner bearing rings of the bearings  4   a  and  4   b  would be axially displaced inwardly due to lateral forces. 
     Since the through axle  5  is disposed radially immediately inside the inner bearing seats  3   a  and  3   b  of the bearings  4   a  and  4   b , the sleeve  6  which is formed as a separate part rests on what is currently the bottom internal wall  42  (see  FIG. 4 ) of the hub shell  2 , when not mounted. 
     In a conventional hub this results in the upper portion of the sleeve wall  46  lying so deep in the insertion opening  47  that the sleeve impedes an insertion of the through axle from the face  11   b.    
     To solve this problem the user must use a tool or his finger, inserting it into the hub from the other face  11   a , lifting and centering the sleeve  6  so as to be able to insert the insertion end  14  of the through axle  5  into the sleeve  6 . Since the user must often also position the entire front wheel such that he can insert the through axle  5  into the adapter rings  12   a  and  12   b  respectively, the user is expected to employ quite some effort of coordination. This is time-consuming and may be annoying. 
     The invention offers the advantage that the radial spacers  7 , which are in particular configured as annular bodies  9 , cause the radial play  8  of the sleeve  6  to be considerably reduced from the original radial distance which is the sum of the distances  18  and  37 , to the radial play  8 . The proportional reduction of play may amount to 30, 50, 75 percent or a still higher percentage, depending on the specific application. 
     The sleeve  6  is lifted by the radial spacers  7  each configured as an O-ring  17  in the exemplary embodiment according to  FIG. 1 , such that the insertion end  14  can be inserted into the inner diameter  34  of the sleeve  6  by the chamfered edge  15 , without any other tool. 
     What is important is that the sleeve  6  which when not mounted is resting on the radially lower inside  42  of the hub shell  2  is centered by means of the spacers  7  so as to allow trouble-free insertion of the through axle  5 . 
     To this end the sleeve  6  must he positioned such and comprise clear dimensions so as to allow insertion of the chamfered edge  15  of the insertion end  14  of the through axle  5 . This is schematically illustrated in  FIG. 4 . It is fulfilled in practice e.g. in the simple case that the chamfered edge  15  having the inner diameter  33  and the clear inner diameter  34  of the sleeve  6  are matched to one another accordingly. 
     The height  38  from the lower inner peripheral surface  42  of the hub shell  2  to the upper sleeve wall  46  of the sleeve  6  must be larger than the height  39  from the inner peripheral surface  42  of the hub shell  2  to the top edge of the chamfer  15 . With the radial play  8  reduced to this degree, ease of insertion of the through axle  5  into the hub and into the sleeve  6  is ensured. When mounted, the operational distance  30  corresponds to half the radial play  8 . 
     In other words, the distance  45  of the center axis  40  of the sleeve  6  from the center axis  41  of the bearings  4   a ,  4   b  or from the through axle  5  to be inserted must be smaller than the radial extension of the chamfer  15  so as to allow the insertion end  14  to be introduced in the inner diameter  34  of the sleeve  6  by the chamfered edge  15 . 
     All of the embodiments in particular employ two radial spacer devices  7  which are axially spaced apart by a distance  19 . The larger the distance between the radial spacer devices  7  from one another, the smaller the risk of the sleeve tilting. Preferably the radial spacer devices  7  are provided as far as possible axially outwardly to establish defined conditions. 
     As illustrated in  FIGS. 3 and 4 , the radial spacer devices  7  may be configured as O-rings  17  and axially secured in grooves  10  on the outside of the sleeve  6 . Or else it is conceivable for the radial spacer devices  7  to be an annular strip or the like, extending around the sleeve  6 . The annular strip may be stuck onto the sleeve or fastened in any other way. 
     Another insertion aid provided in the exemplary embodiment is a projecting edge  27  on the suspension fork which in a normal operating condition is provided above and slightly spaced apart from the adapter rings  12   a  or  12   b . For inserting the through axle  5  in the hub  1 , the suspension fork  100  with the projecting edges  27  can be placed onto the adapter rings  12   a  and  12   b . In this position the chamfer  15  ensures at their insertion ends  14  easy pushing of the through axle  5  into the respective adapter rings  12   a  or  12   b . On the whole there is provided ease of mounting a wheel and the hub  1  to a fork or else to a suspension fork  100 . 
     To fasten the through axle  5  to the suspension fork  100 , a threaded portion  32  of the through axle  5  is screwed to a corresponding thread  26  at the sleeve  21  in the dropout  22  of the suspension fork  100 . An O-ring  24  in a groove  23  provides a sealing means to thus protect the thread  26  from dust and water. 
     Above the through axle  5 , axial appendages or projecting edges  27  are provided on the two stationary tubes  43 ,  44 , each projecting axially inwardly by a length or width  29 , forming end bearings on which a wheel or a hub  1  may be placed for example with the bicycle positioned upside down. 
     This facilitates inserting and threading of the through axle  5  into the opening in the bushings  20  and  21  since the hub is basically already held in the intended position. A small radial distance may be present which may be for example 0.5 or 1 mm, to avoid contact of the outside of the hub and the stationary tubes  43  or  44 . Nevertheless the hub  1  is already approximately in the correct position so as to considerably facilitate threading in. 
     Threading in is likewise facilitated when the fork is placed on the wheel which is stood upright on the ground since the projecting edges  27  likewise ensure good pre-positioning of the suspension fork  100  relative to the hub  1 . 
     In a non-mounted state the adapter rings  12   a  and  12   b  are secured against unintended dropping out by means of the retaining devices  13  configured as closing caps  36 . One closing cap  36  each is pressed into one of the faces  11   a  or  11   b.    
     Each closing cap  36  comprises a through hole through which the axial end of the corresponding adapter ring  12   a  or  12   b  extends, projecting outwardly. Removing the adapter ring from the hub shell  2  requires for the corresponding closing cap  36  to be removed first. The closing caps  36  may consist of a light metal or else of plastic or the like. When mounted, the closing caps  36  have a specific clear distance from the adapter ring which may be small. Absence of contact is significant since the closing caps  36  are rotatingly driven with the hub shell, while the adapter rings  12   a ,  12   b  are stationary when mounted. 
     While the top sides of the dropouts  22  are provided with the projections or projecting edges  27  extending axially inwardly, the bottom sides may be provided with axial recesses  28  at the dropouts  22  such that the axial distance between the stationary tubes is larger at the lowermost end of the stationary tubes  43  and  44  than in the region of the projecting edges  27 . This facilitates both mounting and demounting. One advantage of this is that when inserting a hub  1  or a wheel from beneath, the dropouts  22  are protected better from a contact with the hub  1  since the available width is considerably larger than necessary. In this way, wear and damage to the lower ends of the stationary tubes  43  and  44  occurring in mounting and demounting the wheels is largely avoided such that service life is extended.