Patent Publication Number: US-2016230809-A1

Title: Tiered axial bearing with s-shaped intermediate washer

Description:
FIELD OF INVENTION 
     This application is generally related to rolling bearings and more particularly, to axial rolling bearing arrangements to improve axial load ratings and speed capability. 
     BACKGROUND 
     In some applications, two axial roller bearings are stacked one on top of the other in order to increase the axial load rating and speed capability for a particular support application. Additionally, the diameters of the two axial roller bearings can be different in order to accommodate different radial sizes of axial surfaces being supported. These bearings typically have flat washer-shaped rings with axial flanges for rolling element retention, with a number of rolling elements located between the washer-shaped rings. However, such arrangements use additional space and are typically limited with respect to the widths available. 
     It would therefore be desirable to provide a multi-level axial bearing with reduced space and more flexibility with respect to size while avoiding the drawbacks of the known prior art. 
     SUMMARY 
     In one embodiment, an axial bearing assembly is provided having a first axial end washer having a first radial body defining a first bearing outer race, and a first axial flange on one of a radially inner or outer side, and a second axial end washer having a second radial body defining a second bearing outer race, and a second axial flange on the other of the radially inner or outer side from the first axial flange, and the first and second axial flanges facing in an axial direction toward one another. An intermediate washer is provided with an intermediate radial body with first and second axial sides, the first axial side defining a first bearing inner race and the second axial side defining a second bearing inner race, and first and second axial retention flanges extending from the radial inner and outer ends of the intermediate radial body. The first axial retention flange extends toward the first axial end washer on the other of the radially inner or outer side from the first axial flange, and the second axial retention flange extends toward the second axial end washer on the other of the radially inner or outer side from the second axial flange such that the intermediate radial body and the first and second axial retention flanges define an S-shaped cross-section. A first bearing roller assembly including a first plurality of rolling elements retained in a first cage is located between the first bearing inner race and the first bearing outer race. A second bearing roller assembly including a second plurality of rolling elements retained in a second cage is located between the second bearing inner race and the second bearing outer race. A plurality of retention tabs are formed in the first and second axial retention flanges that engage over a part of the first cage and over a part of the second cage, respectively, to retain the first and second bearing roller assemblies to the intermediate washer. Preferably, outer retention tabs are located on the first and second axial flanges that engage over a part of the first cage and over a part of the second cage, respectively, to retain the first and second axial end washers to the assembly. This results in a more compact, preassembled dual axial bearing that can provide for higher load ratings and increased speed capabilities within a smaller envelope than two separate bearings. Additionally, installation is considerably easier due to the axial bearing assembly with two bearings being retained together. 
     In another aspect, the retention tabs are integrally formed in the intermediate washer, and the outer retention tabs are integrally formed in the first and second axial end washers. 
     Preferably, the retention tabs are pre-formed in the intermediate washer first and second axial retention flanges, and snap over the cages of the first and second roller bearing assemblies during assembly. 
     In one preferred arrangement, the first and second pluralities of rolling elements comprise needle rollers. 
     In one embodiment, the first bearing roller assembly has a different diameter than the second bearing roller assembly. The sizes of the first and second axial end washers and the intermediate washer are adjusted accordingly. However, the roller bearing assemblies could also have the same dimensions. 
     The first cage and the second cage are preferably made from a metallic or polymeric material. 
     Preferably, the first axial end washer, the second axial end washer, and the intermediate washer are each formed as an integral stamped sheet metal part. The sheet metal is preferably bearing grade sheet, and after stamping, the parts are preferably de-burred and/or polished in a vibratory process, hardened, and tempered. 
     In another aspect, a method of assembling a dual axial roller bearing is provided, comprising: 
     forming a first axial end washer having a first radial body defining a first bearing outer race, and a first axial flange on one of a radially inner or outer side; 
     forming a second axial end washer having a second radial body defining a second bearing outer race, and a second axial flange on the other of the radially inner or outer side from the first axial flange, and the first and second axial flanges facing in an axial direction toward one another; 
     forming an intermediate washer having an intermediate radial body with first and second axial sides, the first axial side defining a first bearing inner race and the second axial side defining a second bearing inner race, first and second axial retention flanges extending from the radial inner and outer ends of the intermediate radial body, the first axial retention flange extending toward the first axial end washer on the other of the radially inner or outer side from the first axial flange, and the second axial retention flange extending toward the second axial end washer on the other of the radially inner or outer side from the second axial flange such that the intermediate radial body and the first and second axial retention flanges define an S-shaped cross-section, with a plurality of retention tabs being formed in the first and second axial retention flanges; 
     assembling a first bearing roller assembly by inserting a first plurality of rolling elements into a first cage, and positioning the first bearing roller assembly between the first bearing inner race and the first bearing outer race by snapping the first cage under the retention tabs of the first axial retention flange; and 
     assembling a second bearing roller assembly by inserting a second plurality of rolling elements into a second cage, and positioning the second bearing roller assembly between the second bearing inner race and the second bearing outer race by snapping the second cage under the retention tabs of the second axial retention flange. 
     In a further preferred aspect, the method further includes forming outer retention tabs on the first and second axial flanges that engage over a part of the first cage and over a part of the second cage, respectively, and snapping the first cage under the outer retention tabs of the first axial flange and snapping the second cage under the outer retention tabs of the second axial flange to retain the first and second axial end washers to the assembly. 
     In another aspect, the method preferably includes stamping each of the first axial end washer, the second axial end washer, and the intermediate washer as an integral part from sheet metal. 
     Additional preferred arrangements of the bearing assembly having one or more features of the invention are described below and in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing Summary as well as the following Detailed Description will be best understood when read in conjunction with the appended drawings. In the drawings: 
         FIG. 1  is a plan view of a tiered axial bearing with an S-shaped intermediate washer. 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  in  FIG. 1 . 
         FIG. 3  is a partial perspective view, partly in cross-section, of the bearing assembly of  FIG. 1 . 
         FIG. 4  is a perspective view of the bearing assembly of  FIG. 1 . 
         FIG. 5  is an exploded perspective view of bearing assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “inner,” “outer,” “inwardly,” and “outwardly” refer to directions towards and away from the parts referenced in the drawings. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, c or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import. 
     Referring to the Figures, an axial bearing assembly  10  is shown. The axial bearing assembly  10  includes a first axial end washer  12 , shown in detail in  FIGS. 2 and 5 , having a first radial body  14  defining a first bearing outer race. A first axial flange  18  extends on one of a radially inner or outer side of the first axial end washer  12 . In the embodiment shown, the flange  18  extends from the radially inner side. 
     Still with reference to  FIGS. 2, 3, and 5 , a second axial end washer  22  is provided having a second radial body  24  defining a second bearing outer race  26 . A second axial flange  28  extends from the second radial body  24  on the other of the radially inner or outer side from the first axial flange  18 . As shown in detail in  FIG. 2 , in this case, the second axial flange  28  extends from the radially outer side. However, those skilled in the art will recognize from the present disclosure that the positions of the first and second axial flanges could be switched. The first and second axial flanges  18 ,  28  face toward one another in an axial direction of the axial bearing assembly  10 . 
     Referring to  FIGS. 2 and 5 , an intermediate washer  32  having an intermediate radial body  34  with first and second axial sides  36 ,  38  is provided. The first axial side  36  defines a first inner bearing race  40  and the second axial side  38  defines a second bearing inner race  42 . First and second axial retention flanges  44 ,  46  extend from the radially inner and outer sides of the intermediate radial body  34 . The first axial retention flange  44  extends toward the first axial end washer  12  on the other of the radially inner or outer side from the first axial flange  18 . In the illustrated embodiment, this means that the first axial retention flange  44  extends from the radially outer side of the intermediate radial body  34 . The second axial retention flange  46  extends toward the second axial end washer  22  on the other of the radially inner or outer side from the second axial flange  28 . In this case, the second axial retention flange  46  is located on the radially inner side of the intermediate radial body  34 . Here, based on the opposite extension directions and positions of the first and second axial retention flanges  44 ,  46  on the intermediate radial body  34 , it defines an S-shaped cross-section shown clearly in  FIG. 2 . 
     Still with references to  FIGS. 2-5 , a first bearing roller assembly  50  including a first plurality of rolling elements  52  retained in a first cage  54  is located between the first bearing inner race  40  and the first bearing outer race  16 . A second bearing roller assembly  60  which includes a second plurality of rolling elements  62  retained in a cage  64  is located between the second bearing inner race  42  and the second bearing outer race  26 . As shown in detail in  FIGS. 2-5 , a plurality of retention tabs  48  are formed in the first and second axial retention flanges  44 ,  46  that engage over a part of the first cage  54  and over a part of the second cage  64 , respectively, to retain the first and second bearing roller assemblies  50 ,  60 , to the intermediate washer  32 . 
     Additionally, preferably the first and second axial flanges  18 ,  28  include outer retention tabs  30  that engage over a part of the first cage  54  and over a part of the second cage  64 , respectively, to retain the first and second axial washers  12 ,  22  to the assembly  10 , as shown in  FIGS. 2, 4, and 5 . 
     As shown in  FIGS. 1, 4, and 5 , the retention tabs  48  on the intermediate washer  32  are preferably equally circumferentially spaced about the inner and outer peripheries on the retention flanges  44 ,  46 . They are preferably at least two of the retention tabs  48  on the first axial retention flange  44  and at least two of the retention tabs  48  on the second axial retention flange  46 . Preferably, there are at least four equally circumferentially spaced retention tabs on each of the first and second axial retention flanges  44 ,  46 . However, the number of retention tabs  48  can be varied depending on the bearing size and application. 
     With respect to the outer retention tabs  30 , preferably, as shown in  FIGS. 3 and 5 , there are at least two and more preferably 4 of the outer retention tabs  30  located on the first axial flange  18 , and these are preferably equally circumferentially spaced apart. With respect to the second axial flange  28 , this preferably includes at least two and preferably four or more of the outer retention tabs  30  that are also equally spaced apart in the circumferential direction. 
     The retention tabs  48  are preferably integrally formed in the first and second axial retention flanges  44 ,  46  of the intermediate washer  32  and the outer retention tabs  30  are preferably integrally formed in the first and second axial flanges  18 ,  28  of the first and second axial end washers  12 ,  22 , respectively. 
     Preferably, the retention tabs  48  snap over the cages  54 ,  56  of the first and second roller bearing assemblies  50 ,  60  during assembly. This can be achieved due to the flexibility provided by the cages  54 ,  64  in being sufficiently compliant so that the retention tabs can snap thereover and retain the first and second roller bearing assemblies  50 ,  60  in position against the intermediate washer  32  so that the axial bearing assembly  10  can be pre-assembled. Preferably, the same type of fit is provided for the first and second end washers  12 ,  22 , with the cages  54 ,  64  of the first and second roller bearing assemblies  50 ,  60 , being sufficiently compliant in order to allow the outer retention tabs located on the first and second axial flanges  18 ,  28  of the first and second axial end washers  12 ,  22  to snap over the first and second cages  54 ,  64 , respectively. This allows the entire unit to be pre-assembled with first and second axial end washers  12 ,  22 , the intermediate washer  32 , and the first and second bearing roller assemblies  50 ,  60 , providing a smaller envelope than would previously be available using two separate axial roller bearings while providing the same capacity for axial load as well as speed capability. 
     Depending upon the desired configuration, the first bearing roller assembly  50  has a different diameter than the second roller bearing assembly  60 , as shown in  FIGS. 1 and 2 . This allows for a tiered assembly as shown in  FIG. 2 . It is also possible for the first and second bearing roller assemblies  50 ,  60  to be the same diameter. Further, it is also within the scope of the invention to provide two or more intermediate washers between the first and second axial end washers  12 ,  22  with possibly third or additional bearing roller assemblies located therebetween to provide a pre-assembled axial bearing assembly retained together as one unit having three or more bearing roller assemblies located therein. 
     In the preferred embodiment shown, the first and second plurality of rolling elements  52 ,  62  comprise needle rollers. Preferably, the first cage and second cage  54 ,  64  are made from a metallic or polymeric material. Thus, the cages  54 ,  64  can be made from stamped sheet metal or injection molded polymeric materials, depending upon the particular application. 
     Preferably, the first axial end washer  12 , the second axial end washer  22 , and the intermediate washer  32  are each formed as an integral stamped sheet metal part. These parts are typically stamped from a bearing grade steel sheet metal, subjected to a vibratory cleaning and/or deburring, prior to being hardened and tempered. Additional processing, such as polishing of the raceways can also be provided, depending upon the particular application and surface finish desired. 
     A method of assembling a dual axial roller bearing  10  is also provided which includes forming the first axial end washer  12 , the second axial end washer  22  as well as the intermediate washer  32  as described above. A plurality of the retention tabs  48  are formed in the first and second axial retention flanges  18 ,  28 . The first bearing roller assembly and second bearing roller assembly  50 ,  60  are assembled. The first bearing roller assembly  50  is positioned between the first bearing inner race  40  and the first bearing outer race  16  and is snapped in position by snapping the first cage  54  under the retention tabs  48  of the first axial retention flange  44 . The second roller bearing assembly  60  is also positioned between the second bearing inner race  42  and the second bearing outer race  26  by snapping the second cage  64  under the retention tabs  48  of the second axial retention flange  46 . Preferably, the first and second axial end washers  12 ,  22  are also engaged by the outer retention tabs  30  formed on the first and second axial flanges  18 ,  28  being snapped over the first cage, with the first cage moving under the outer retention tabs  30  of the first axial flange  18  and by snapping the second cage  64  under the outer retention tabs  30  of the second axial flange  28  to retain the first and second axial end washers  12 ,  22  to the bearing assembly  10 . 
     As a result of the assembly, a more compact, pre-assembled axial bearing assembly  10  is provided, which can have a tiered configuration depending upon the diameters of the first bearing roller assembly  50  and the second bearing roller assembly  60  and the use of correspondingly sized first and second axial end washers  12 ,  22 . 
     Having thus described various embodiments of the present axial bearing assembly in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description above, could be made in the assembly without altering the inventive concepts and principles embodied therein. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.