Abstract:
A steering wheel mounting assembly comprising first and second stationary rings, the second stationary ring being adapted for connection to a vehicle frame. The assembly further comprises a steering hub having a spindle with a radial flange extending therefrom. The spindle is adapted for connection with a steering shaft and the radial flange is adapted for connection with a steering wheel. The spindle has a first bearing raceway for engaging a bearing of the first stationary ring and a second bearing raceway for engaging a bearing of the second stationary ring. The steering hub has at least one opening that defines a bearing surface. A friction roller assembly, having a shaft with a third bearing thereabout, is positioned in the opening such that as the third bearing rotates relative to the bearing surface, the third bearing moves radially outward and the shaft engages the first and second cylindrical raceways.

Description:
BACKGROUND 
       [0001]    The present invention relates to a steering assembly. More particularly, the present invention relates to a steering assembly having a steering hub mounted to a steering wheel. 
         [0002]    Referring to  FIG. 1 , a prior art steering assembly  10  is shown. The steering assembly  10  includes a steering wheel  12  mounted on a radial frame  14 . The radial frame  14  includes a central hub  16  that is mounted on a steering shaft  18 . Rotation of the steering wheel  12  is translated through the frame  14 , and thereby the hub  16 , to cause rotation of the steering shaft  18 . 
         [0003]    A mounting frame  20  is attached to and rotates with the radial frame  14 . The mounting frame  20  is configured to support an air bag assembly  22  and other components. The air bag assembly  22  is fixed to the mounting frame  20 , and therefore, rotates with the steering wheel  12 . Since the orientation of the air bag assembly  22  continuously changes with rotation of the steering wheel  12 , the air bag assembly  22  must have a substantially symmetrical design so that the air bag thereof will deploy with a known configuration no matter the orientation of the air bag assembly  22  at the time of deployment. 
         [0004]    Furthermore, it is not desirable to mount driver controls and displays on the mounting frame  20  since the mounting frame  20  rotates with the steering wheel  12 . 
       SUMMARY 
       [0005]    The present invention relates to a steering wheel mounting assembly. The assembly comprises first and second stationary rings. The first stationary ring has a first bearing and a first cylindrical raceway. The second stationary ring has a second bearing and a second cylindrical raceway and is adapted to be fixed to a vehicle frame. The assembly further comprises a steering hub having a spindle with a radial flange extending therefrom. The spindle is adapted for connection with a steering shaft, and the radial flange is adapted for connection with a steering wheel. The spindle has a first bearing raceway for engaging the first bearing and a second bearing raceway for engaging the second bearing. The steering hub has at least one opening through the steering hub radial flange. The opening defines a bearing surface. A friction roller assembly is positioned in the opening. The friction roller assembly has a shaft with a third bearing thereabout. The friction roller assembly is positioned in the opening such that the third bearing rotates relative to the bearing surface, the third bearing moves radially outward, and the shaft engages the first and second cylindrical raceways. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a side elevation of a prior art steering assembly in partial cross section; 
           [0007]      FIG. 2  is an exploded, isometric view of a mounting assembly that is a first embodiment of the present invention; 
           [0008]      FIG. 3  is an isometric view, in section, of a stationary ring of the present embodiment of the invention; 
           [0009]      FIG. 4  is an assembled, isometric view of the mounting assembly of  FIG. 2  in cross section; 
           [0010]      FIG. 5  is a front elevation view, in partial section, of the assembled mounting assembly of  FIG. 2 ; 
           [0011]      FIG. 6  is a cross sectional view along the line  6 - 6  in  FIG. 5 ; 
           [0012]      FIG. 7  is an isometric view of the steering hub of the present embodiment of the invention; 
           [0013]      FIG. 8  is an isometric view, in section, of the steering hub of  FIG. 7 ; 
           [0014]      FIG. 9  is an isometric view of a friction roller assembly of the present embodiment of the invention; 
           [0015]      FIG. 10  is an isometric view of the roller cage of the present embodiment of the invention; and 
           [0016]      FIG. 11  is a cross sectional view along the line  11 - 11  in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The present invention will be described with reference to the accompanying drawing figures wherein like numbers represent like elements throughout. Certain terminology, for example, “top”, “bottom”, “right”, “left”, “front”, “frontward”, “forward”, “back”, “rear” and “rearward”, is used in the following description for relative descriptive clarity only and is not intended to be limiting. 
         [0018]    Referring to  FIGS. 2-6  and  10 , a mounting assembly  50  that is a first embodiment of the present invention is shown. The mounting assembly  50  generally comprises a pair of stationary rings  60 ,  60 ′, a steering hub  70 , a plurality of friction roller assemblies  90  and roller cage  100 . One of the stationary rings  60 ′ is configured for mounting to the vehicle frame (not shown). The steering hub  70  is configured to be attached to a steering shaft (not shown) and to be attached to the steering wheel (not shown). The steering hub  70  may be rotatably supported by the stationary ring  60 ′. The steering hub  70  in turn supports the other stationary ring  60  which is configured for supporting desired components, for example, an air bag assembly or driver controls and displays. The friction roller assemblies  90  are positioned within the steering hub  70  and provide frictional contact between the roller shaft and cylindrical raceways on the two stationary rings  60 ,  60 ′. The roller cage  100  maintains the orientation of the roller assemblies  90  and reduces skewing of the roller assemblies  90 . 
         [0019]    Exemplary stationary rings  60 ,  60 ′ will be described with reference to  FIGS. 2-4 . The stationary rings  60 ,  60 ′ have a radial plate  62 . The radial plate  62  is provided with a plurality of holes  63 . The holes  63  in the stationary ring  60 ′ are configured for fastening the stationary ring  60 ′ to the vehicle frame (not shown). The holes  63  in the stationary ring  60  are configured for mounting desired components, for example, an air bag assembly or driver controls and displays, to the stationary ring  60 . Each stationary ring  60 ,  60 ′ has a first annular wall  64  extending from the radial plate  62 . The inner surface of the first annular wall  64  defines a cylindrical raceway  66 . The cylindrical raceway  66  of each stationary ring  60 ,  60 ′ is configured to engage the roller surfaces of the roller assemblies  90  as will be described hereinafter. Each stationary ring  60 ,  60 ′ has a second annular wall  67  extending from the other side of the radial plate  62 . The inner surface of the second annular wall  67  has a concave bearing outer raceway  68  configured to receive rolling elements  69  of the ring support bearing. 
         [0020]    Referring to  FIGS. 7-8 , an exemplary steering hub  70  is shown. The steering hub  70  includes a central spindle  72  with a radial flange  80  extending outward therefrom. The central spindle  72  has a central bore  74  with a tapered surface  76  for mating with the steering shaft (not shown). The tapered surface  76  is provided with a spline portion for increasing the torque load capacity in case a heavy torque load is transferred between the steering hub  70  and the steering shaft. The outer cylindrical surface of the spindle  72  provides a concave bearing inner raceway  79 ,  81  on each side of the radial flange  80 . The concave raceways  79 ,  81  are configured for receiving the rolling elements  69  of the bearings of the respective stationary rings  60 ,  60 ′. Referring to  FIG. 6 , the rolling elements  69  positioned between the stationary ring concave bearing outer raceway  68  and the steering hub concave bearing inner raceway  79  retain the steering hub  70 , axially and radially, relative to the stationary ring  60 ′. The rolling elements  69  positioned between the stationary ring concave bearing outer raceway  68  and the steering hub concave bearing inner raceway  81  retain the stationary ring  60 , axially and radially, relative to the steering hub  70 . The steering hub  70  is thereby supported for free rotation relative to the stationary rings  60 ,  60 ′. Since the steering wheel (not shown) is connected to the radial flange  80  of the steering hub  70  and the steering shaft (not shown) is connected to the spindle  72  of the steering hub  70 , rotation of the steering wheel will result in direct rotation of the steering shaft. 
         [0021]    To keep the first ring  60  stationary and in phase with the second ring  60 ′, the steering hub  70  is configured to receive friction roller assemblies  90 . There are two sets of openings  82 ,  84  provided through the flange  80 . Each of the first openings  82  is provided with a bearing surface  86  configured to provide a bearing seat for the friction roller assemblies  90  as will be described hereinafter. As can be seen in  FIG. 5 , each opening  82  has a diameter greater than the outer diameter of the friction roller assembly outer bearing ring  99 . A shoulder  88  is provided at the end of each bearing seat to provide an axial stop for the friction roller assemblies  90 . The second openings  84  are configured to accommodate the anti-skewing roller cage  100  as will be described hereinafter. In one embodiment, there are three of each type of opening  82 ,  84  in alternating fashion. However, more or fewer of each type of opening  82 ,  84  may be provided, and they may be arranged in any desired configuration. 
         [0022]    Referring to  FIG. 9 , an exemplary friction roller assembly  90  is shown. The friction roller assembly  90  has a shaft  92  that defines two cylindrical bearing surfaces  93  and  95 . The bearing surfaces  93 ,  95  are configured to bear against the cylindrical raceways  66  of the stationary rings  60 ,  60 ′ as will be described hereinafter. The friction roller assembly  90  also includes an integrated bearing  94  between the two bearing surfaces  93 ,  95 . The bearing  94  includes an inner bearing raceway  97 , which can be formed integral with the shaft  92 , an outer raceway  99  and rolling elements  98  positioned therebetween. The outer raceways  99  are configured to engage the first opening bearing surfaces  86  as will be described hereinafter. 
         [0023]    Referring to  FIGS. 4-6  and  11 , in the fully assembled state, the friction roller assemblies  90  are positioned in the first openings  82  of the steering hub  70  with the bearing outer rings  99  seated inwardly against bearing seats  86  toward the center of the steering hub  70 . The bearings  94  contact the shoulders  88  to axially position the friction roller assemblies  90 . The bore diameter of openings  82  is greater than the outer diameter of bearing ring  99  such that the center of each bearing  94  is offset by a distance e from the center of the respective opening  82 . Since the bearings  94  are eccentric to the center of the openings  82 , and thereby the bearing seats  86 , the bearing seats  86  act as a camming surface. The bearing seats  86  need not extend about the entire circumference of the openings  82 , nor do the bearing seats  86  need be of circular shape. The bearing seats  86  can be of various configurations to push the bearing outer ring  99  outwardly as it rolls along the cam surface. Also, resilient components (not shown), such as leave springs, may be provided between the bearing seats  86  and bearing outer rings  99  to push the bearings  94  outwardly and preload the friction roller assemblies  90 . 
         [0024]    To minimize skewing of the friction roller assemblies  90  as the steering hub  70  is rotated, an anti-skewing roller cage  100  is assembled around the steering hub  70 . As shown in  FIG. 10 , the anti-skewing roller cage  100  contains two plates  102 ,  104  and a set of side-walls  106  between the two plates  102 ,  104 . Side-walls  106  are fixed at their ends to the plates  102 ,  104  to form a cage, preventing the plates  102 ,  104  from rotating relative to each other. Slots  103 ,  105 , respectively, are provided in each plate  102 ,  104  for receiving the shafts  92  of the friction roller assemblies  90 . Slots  103  on plate  102  are aligned with respective slots  105  on the other plate  104 . Referring to  FIGS. 4-6  and  11 , in the fully assembled state, the side-walls  106  are received in the openings  84  on the steering hub flange  80 . Each pair of slots  103 ,  105  on roller cage  100  receives a friction roller assembly  90 . The cage  100  may float slightly relative to the steering hub  70  about the rotation axis. As the cage  100  floats, it rotates all the friction roller assemblies  90  with it as a unit, i.e., the cage  100  confines each friction roller assembly at both its ends in the circumferential direction, preventing the roller assembly  90  from skewing. The friction roller assembly  90 , however, is free to move outwardly in the radial direction with respect to the cage  100 . Relative rotation between the steering hub  70  and the cage  100  causes the friction roller assemblies  90  to be pushed radially outward by the eccentrically positioned bearings  94  with respect to the bearing seats  86 . While the anti-skewing cage  100  can be employed, there are other ways to minimize skewing of the friction roller assembly shafts  92 . For example, the single bearings  94  may be replaced with double bearings. 
         [0025]    In operation, the central spindle  72  of the steering hub  70  connects to a steering shaft, and the flange  80  of the steering hub  70  connects to a steering wheel. The second stationary ring  60 ′ is fixed to the steering column. As the operator turns the steering wheel, the steering hub  70  tends to rotate relative to the cage  100  and friction roller assemblies  90 . This produces a cam action that forces each friction roller assembly  90  to move radially outward with two cylindrical surfaces  93 ,  95  of the shaft  92  firmly against the two raceways  66  of the stationary rings  60 ,  60 ′. Thus, friction force between the cylindrical surfaces  93 ,  95 , of the shaft  92  and the two raceways  66  of the stationary rings  60 ,  60 ′ is generated. The friction force at each contact enables the roller shafts  92  to roll, rather than slide, along the raceways  66  of the stationary ring  60 ,  60 ′ as the friction roller assemblies  90  orbit with the steering hub  70 . The counter rotating motion of the roller shafts  92  ensures that the first ring  60  always remains in phase with the second ring  60 ′. Since the second ring  60 ′ is fixed to the steering column, the first ring  60  remains in phase and stationary with respect to the column. 
         [0026]    While in the illustrated embodiment all of the friction roller assemblies  90  engage a camming surface and thereby all provide a frictional load, such is not required. For example, it may be desirable to have only one friction roller assembly  90  with a cam loading mechanism and the other two friction roller assemblies  90  without cam mechanisms. One such method is to fix the bearings  94  in their seats for the non-camming friction roller assemblies  90 . 
         [0027]    Embodiments of the present invention provide a friction load to keep the stationary rings  60 ,  60 ′ in phase with substantially zero backlash at frictional contacts. In particular, the friction roller assemblies  90  provide smooth and quiet operation and eliminate the lash and variation in torque experienced during operation of gear driven steering systems. Moreover, embodiments require fewer components than conventional designs. 
         [0028]    The embodiments described above are merely exemplary embodiments, and other embodiments can be practiced that fall within the scope of embodiments of the invention.