Abstract:
An annular hub ( 11 ) has flange ( 2 ) for connecting to a wheel and an axial cylindrical surface ( 14 ) for mounting a bearing unit ( 7 ). An intermediate annular member ( 30 ) is coupled for rotation to a driving axle shaft ( 1 ) by a first toothed/splined coupling ( 21, 31 ) and to the hub ( 11 ) by a second toothed/splined coupling ( 22, 32 ).

Description:
DESCRIPTION  
         [0001]    The present invention refers to a hub-bearing assembly for a driving wheel of a vehicle particularly a light truck.  
           [0002]    For a better understanding of the state of the art and problems relating thereto, there will be at first described a hub-wheel assembly of conventional design, shown in FIG. 2 of the attached drawings.  
           [0003]    With reference to FIG. 2, a hub  11  of elongated form has a flanged portion  2  with axial bores  3  for bolts  4  for fastening to a brake disc  5 . The hub  11  is accommodated in a stationary tubular housing  6  and rotatably supported by means of a bearing unit, schematically indicated  7 , which is radially interposed between the tubular housing  6  and the cylindrical part of the hub  11 . The bearing unit  7  is of the so-called first generation type, comprising a stationary outer ring, a rotatable inner ring and rolling bodies interposed therebetween. For supporting a brake member  9 , an annular member  8  is welded on the outer surface of the tubular housing  6 . The cylindrical gap  10  defined between the cylindrical part of the hub  11  and the housing  6  is normally filled with lubricant oil.  
           [0004]    An object of the present invention is to provide a hub-bearing assembly that may simplify assembling and maintenance operations.  
           [0005]    An other object of the invention is to make use of a hub and a bearing of smaller size with respect to the above discussed prior art, with a consequent saving of weight and costs.  
           [0006]    These and other objects and advantages, that will be better understood hereinafter, are attained according to the present invention by a hub-bearing assembly as defined in the appended claims. 
       
    
    
       [0007]    There will now be described, by way of a non-limiting example, a preferred embodiment of a hub-bearing assembly according to the present invention, reference being made to the accompanying drawings in which:  
         [0008]    [0008]FIG. 1 is a partially sectioned axial cross-sectional view of an embodiment of a hub-bearing assembly according to the invention; and  
         [0009]    [0009]FIG. 2 is a schematic axial cross-section of a hub-bearing unit of conventional design. 
     
    
       [0010]    With reference to FIG. 1, and using the same reference numerals already adopted in FIG. 2 to indicate equal or like parts, numeral  1  indicates an axle shaft for a driving wheel (not shown) of a motor vehicle, particularly a light truck. Naturally, reference to this possible field of use should not be interpreted as in any way limiting the scope of the patent.  
         [0011]    The axle shaft  1  is accommodated in a conventional stationary tubular housing  6  on the outer surface of which there is welded an annular member  8  constituting a flange for supporting a brake bracket  9 .  
         [0012]    An annular hub indicated  11  is formed separately from the axle shaft  1  and coupled for rotation and axially thereto, as will be described in detail in the following. The hub  11  has a central axial tubular portion  12 . At the axially outer end, the hub  11  forms a radial flange portion  2  extending in a radially outer direction with axial bores  3  for bolts  4  for fastening to a wheel and a brake disc (not shown). At the side of the outer flange  2 , the tubular portion  12  has an outer surface of cylindrical shape  14  joining a radial shoulder surface  15 .  
         [0013]    A bearing unit  7  of the so-called second generation is mounted on the cylindrical surface  14  of the hub, at a position outside the tubular housing  6 . The bearing unit includes a pair of radially inner half-races  71 ,  72  axially located side-to-side and fast for rotation with the hub, a radially outer stationary race  73 , and a dual set of rolling bodies  74 ,  75  (preferably cone rollers) radially interposed between the outer race  73  and the inner half-races  71 ,  72 . The outer race  73  forms a radially outwardly extending flange  76  in which there are obtained axial bores  77  for bolts  18  for fastening to the stationary tubular housing  6 . The fastening bolts  18  pass through axially aligned bores  19  and  20  obtained in the brake bracket  9  and the annular flange  8  of the tubular housing  6 , respectively.  
         [0014]    In order to transmit the driving torque from the axle shaft  1  to the hub  11 , these two members are coupled for rotation by an intermediate annular member  30  having a first internal toothing or spline  31  coupled with a corresponding outer toothing or spline  21  formed on the end portion of the axle shaft  1 , and a second inner toothing or spline  32  coupled with a corresponding outer toothing or spline  22  formed on the hub  11 . The outer spline  22  of the hub is formed on the cylindrical surface  12  of the hub at a zone adjacent to the zone where the inner half-race  72  of the bearing is fitted. In the preferred embodiment shown in the drawing, the intermediate annular member  30  has a substantially L-shaped axial cross-section, with a tubular or cylindrical axial portion  33  forming internally the first toothing or spline  31 , and a radial flange portion  34  the central opening of which forms the second internal spline or toothing  32 .  
         [0015]    The hub  11  forms a tubular portion  25  (shown in phantom line in its initial indeformed condition) protruding beyond the flange portion  34  of the intermediate annular member  30 . After the annular member  30  has been fitted onto the tubular portion  25 , the part of this which protrudes beyond the flange portion  34  is cold deformed, preferably by rolling, in a radially outer direction against the flange portion  34  so as to form a plastically deformed edge  26 . The deformed edge  26  axially locks the annular intermediate member  30  on the hub and eliminates axial play between the opposite shoulder  15  of the hub, the inner half-races  71 ,  72  and the intermediate annular member  30 . In this way the bearing unit  7  remains axially pre-loaded onto the hub.  
         [0016]    Then, the hub  11  is clamped axially to the axle shaft  1  by means of a central bolt  27  fitted into a central axial bore  16  formed by a radial flange portion  15  extending in a radially inner direction from the tubular portion  12  of the hub. Finally, after having rotated the outer race  73  so as to align the bores  77  with the bores  19  and  20  of the brake bracket  9  and the annular flange  8 , the bolts  18  for fastening to the tubular housing  6  are inserted and tightened.  
         [0017]    At the interface between the bearing outer race  73  and the brake bracket  9  there is fitted an O-ring  28  hermetically sealing the cylindrical gap  10  defined between the axle shaft  1  and the housing  6  and containing lubricant oil.  
         [0018]    While a specific embodiment of the invention has been disclosed, it is to be understood that such disclosure is to be regarded as an exemplary embodiment of the hub-bearing assembly, and that modifications concerning the shape and location of parts, and constructional and functional details may be carried out.