Abstract:
A bearing assembly comprising a cage, a plurality of rollers and a sleeve. The cage comprises a central portion extending between a pair of radial flanges. The central portion includes a plurality of roller retaining pockets configured to receive and prevent substantial radial movement of rollers positioned therein in a radial direction. The sleeve is positioned between the radial flanges with the radial flanges radially overlapping the sleeve. The sleeve is retained between the flanges prevents substantial radial movement of the rollers in the opposite direction.

Description:
BACKGROUND  
       [0001]     The present invention relates generally to roller bearings and, more particularly, to a unitized roller bearing assembly.  
         [0002]     Referring to  FIG. 1 , a prior art roller bearing assembly  100  is illustrated. The roller bearing assembly  100  generally includes a plurality of rollers  102  retained within a cage  104 . The cage  104  includes a plurality of pockets in which the rollers  102  are positioned and retained. A cup  106  is provided about the outside of the cage  104  and roller  102  assembly to provide an outer bearing surface for the rollers  102 . Alternatively, the cup  106  may be provided on the inside of the cage  104  and roller  102  assembly to provide an inside bearing surface. Flanges  108  and  110  extending radially from the cup  106  unitize the assembly and thereby allow the cup  106  to prevent radially outward movement of the rollers  102 . Various means have been employed to configure the pockets, for example, tabs extending in to the pockets, to prevent radial movement of the rollers  102  in a direction opposite of the cup  106 .  
         [0003]     While the cup  106  has provided an adequate means to unitize the assembly, it has some drawbacks. For example, during manufacture, one of the flanges  108  or  110  is generally left uncurled so that the cage  104  and roller  102  assembly may be positioned within the cup  106 . Thereafter, a secondary procedure is required to curl the uncurled flange  108  or  110 . Additionally, bearing assemblies are often utilized in confined environments, for example, a vehicle transmission, where space is at a premium. The axial thickness of the flanges  108  and  110  must be accommodated by reducing the length of the cage  104  and thereby the rollers  102 .  
       SUMMARY  
       [0004]     The present invention provides a bearing assembly comprising a cage, a plurality of rollers and a sleeve. The cage comprises a central portion extending between a pair of radial flanges extending in a first radial direction. The central portion includes a plurality of roller retaining pockets. Each roller retaining pocket is configured to prevent substantial radial movement of a roller positioned therein in a second radial direction opposite the first radial direction. The sleeve is positioned between the radial flanges. The radial flanges extend a distance in the first radial direction such that the flanges radially overlap the sleeve whereby the sleeve is retained between the flanges and the sleeve prevents substantial radial movement of the rollers in the first radial direction. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES  
       [0005]      FIG. 1  is a partial view, in cross section, of a bearing assembly of the prior art.  
         [0006]      FIG. 2  is an isometric view of a bearing assembly that is a first embodiment of the present invention with the rollers omitted and the sleeve partially omitted.  
         [0007]      FIG. 3  is a cross-sectional view of the bearing assembly of  FIG. 2  with the rollers in place.  
         [0008]      FIG. 4  is a cross-sectional view similar to  FIG. 3 , illustrating an first alternate embodiment of the present invention.  
         [0009]      FIG. 5  is a cross-sectional view similar to  FIG. 3 , illustrating a second alternate embodiment of the present invention.  
         [0010]      FIG. 6  is a cross-sectional view similar to  FIG. 3 , illustrating a third alternate embodiment of the present invention.  
         [0011]      FIG. 7  is a cross-sectional view similar to  FIG. 3 , illustrating a fourth alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     Referring to  FIGS. 2 and 3 , a bearing assembly  10  that is a first embodiment of the present invention will be described. The bearing assembly  10  generally includes a bearing cage  20 , a plurality of rollers  40  and a sleeve  50 . The bearing cage  20  of the present embodiment has radial flanges  22  and  24  joined together by crossbars  26 . Crossbars  26  have a central portion  28  offset radially inwardly from laterally outward portions  27  and  29 . The cage  20  is preferably manufactured from a stamped sheet that is wrapped to form a hoop and then welded, for example, at  36  in  FIG. 2 . Other manufacturing methods may also be utilized.  
         [0013]     Adjacent crossbars  26  are spaced to define a plurality of roller retaining slots  30  about the cage  20 . Each slot  30  is sized to retain a roller  40  for rotation therein. In the present embodiment, the radially inward central portions  28  include a plurality of circumferential tabs  32  extending in to the roller retaining slots  30 . Opposed tabs  32  define an area having a width R less than the width W of the slot  30  such that the tabs  32  prevent radially inward movement of the rollers  40 .  
         [0014]     To prevent radially outward movement of the rollers  40 , sleeve  50  is positioned about the rollers  40  between the cage flanges  22  and  24 . The sleeve  50  is a cylinder having an inside surface  52  having a diameter approximately equal to the outside diameter defined by the rollers  40  such that the inside surface  52  provides an outer bearing surface for the rollers  40 . The sleeve  50  may be manufactured from a drawing process, cutting of a cylindrical tube, welding of a wrapped strip, or various other manufacturing techniques. To maintain the sleeve  50  about the rollers  40 , each of the cage flanges  22 ,  24  extends radially outward beyond the outer diameter of the rollers  40 . As such, the flanges  22  and  24  radially overlap the sleeve  50  to retain the sleeve  50  and limit axial movement thereof, as shown in  FIG. 3 . The overlap is such that the flanges  22  and  24  do not extend radially outward past the outer surface of the sleeve  50  such that the flanges  22  and  24  do not interfere with the rotation of the bearing  10 .  
         [0015]     To facilitate positioning of the sleeve  50  between the flanges  22  and  24 , one or both outer edges of the sleeve  50  may include a tapered surface  54  such that the sleeve  50  may be snap fit over one of the flanges  22 ,  24 . The amount of axial retainment of the sleeve  50  required by the flanges  22  and  24  during operation is minimal, and therefore, the amount of radial overlap between the flanges  22  and  24  and the sleeve  50  does not have to be significant, only enough to unitize the assembly  10  under minimal loads encountered during shipping or the like. As such, the sleeve  50  may be snap fit passed one of the flanges  22 ,  24 . Alternatively, the sleeve  50  may be a flat strip that is wrapped around the cage  20  and welded together after it is positioned between the flanges  22  and  24 . In yet another alternative, the cage  20  may be positioned within the sleeve  50  prior to welding of the cage  20 . That is, the free ends of the wrapped cage  20  may be overlapped such that the cage  20  has a reduced diameter and can be positioned within the sleeve  50 . Once positioned within the sleeve  50 , with the flanges  22  and  24  about the sleeve  50 , the free ends of the cage  20  are abutted, thereby returning the cage  20  to its natural diameter, and the cage  20  is welded. Other means of positioning the sleeve  50  within the flanges  22  and  24  may also be utilized.  
         [0016]     The present invention allows a cylindrical sleeve  50  without the need to curl the ends of the outer race, as required in the prior art unitized assembly. Furthermore, the thickness of the curled ends of the prior art assembly is also removed. As such, the cage  20  of the present invention may be made longer (distance from one flange  22  to the other  24 ), thereby allowing longer rollers  40  resulting in an increased capacity of the bearing assembly  10 .  
         [0017]     Referring to  FIG. 4 , a bearing assembly  10 ′ that is a second embodiment of the present invention is shown. The bearing assembly  10 ′ is substantially the same as in the previous embodiment and includes a cage  20 ′, a plurality of rollers  40  and a sleeve  50 , with the rollers  40  and sleeve  50  being substantially identical as to the previous embodiment. The primary distinction versus the previous embodiment is that the central portions  28 ′ of the cage  20 ′ have an expanded width to define the area of reduced width R, as opposed to the tabs of the previous embodiment. As such, the central portions  28 ′ prevent radially inward movement of the rollers  40 . The radial flanges  22  and  24  again radially overlap and thereby retain the sleeve  50  which prevents radially outward movement of the rollers  40 .  
         [0018]     Referring to  FIG. 5 , a bearing assembly  10 ″ that is a third embodiment of the present invention is shown. The bearing assembly  10 ″ is substantially the same as in the previous embodiments and includes a cage  20 ″, a plurality of rollers  40  and a sleeve  50 , with the rollers  40  and sleeve  50  being substantially identical as to the previous embodiment. In the present invention, the central portions  28 ″ of the cage  20 ″ extend radially outward from the laterally outward portions  27 ″ and  29 ″ that are positioned radially inward. Each laterally outward portion  27 ″ and  29 ″ defines tabs  32 ″ extending into the roller retaining slots  30  to define the area of reduced width R. As such, the tabs  32 ″ of the laterally outward portions  27 ″ and  29 ″ prevent radially inward movement of the rollers  40 . The radial flanges  22  and  24  again radially overlap and thereby retain the sleeve  50  which prevents radially outward movement of the rollers  40 . The central portions  28 ″ may also be provided with radially outward retaining means, but such is not required as the sleeve  50  prevents radially outward movement.  
         [0019]     These various embodiments illustrate that various means may be provided opposite the sleeve  50  to prevent radial movement of the rollers  40  in a direction opposite the sleeve  50 . The various means are not limited to the illustrated embodiments, but may include other configurations.  
         [0020]     Referring to  FIG. 6 , a bearing assembly  60  that is a fourth embodiment of the present invention is shown. The bearing assembly  60  is an inverted version of the bearing assembly  10  of the first embodiment. That is, the sleeve  100  is positioned within the rollers  40  and has an outside surface  102  that serves as an inside bearing surface for the rollers  40  and prevents radially inward movement of the rollers  40 . The cage  70  includes a plurality of crossbars  76  extending between radial flanges  72  and  74 . In the present embodiment, the flanges  72  and  74  extend radially inward such that the flanges  72  and  74  radially overlap the sleeve  100 . Each crossbar  76  includes a radially outward central portion  78  extending between laterally outward portions  77  and  79 . Similar to the first two embodiments, the central portions  78  include tabs, an increased thickness, or other means (not shown) to prevent radial outward movement of the rollers  40 . The bearing assembly  60  may be manufactured in various manners, including those described with reference to the earlier embodiments. For example, the sleeve  100  may include tapered edges  104  to facilitate snap fitting of the sleeve within the flanges  72  and  74 . Alternatively, the cage  70  may be wrapped about the sleeve  100  and thereafter welded. Other methods may also be utilized.  
         [0021]     Referring to  FIG. 7 , a bearing assembly  60 ″ that is a fifth embodiment of the present invention is shown. The bearing assembly  60 ″ is an inverted version of the bearing assembly  10 ″ of the third embodiment. As in the previous embodiment, the sleeve  100  is positioned within the rollers  40  and has an outside surface  102  that serves as an inside bearing surface for the rollers  40  and prevents radially inward movement of the rollers  40 . The cage  70 ″ includes a plurality of crossbars  76  extending between radial flanges  72  and  74  with the flanges  72  and  74  extending radially inward such that the flanges  72  and  74  radially overlap the sleeve  100 . Each crossbar  76  includes radially outward laterally outward portions  77 ″ and  79 ″, with the central portion  78 ″ being radially inward therefrom. Similar to the third embodiment, the laterally outward portions  77 ″ and  79 ″ include tabs, an increased thickness, or other means (not shown) to prevent radial outward movement of the rollers  40 .