Abstract:
A bearing assembly is provided having a roller bearing with an inner raceway fitted around the journal portion of an axle. An outer raceway combines with the inner raceway to receive roller elements. A backing ring is centered to the shaft fillet. An annular wear ring is positioned between the inner race and the backing ring. An improved lubricant seal arrangement is provided between the wear ring and the supporting outer raceway.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to sealed shaft journal bearings and more particularly to an improved bearing assembly seal arrangement. Roller bearing assemblies incorporating two rows of tapered roller bearings preassembled into a self-contained, pre-lubricated package for assembly onto journals at the ends of axles or shafts are known. Such bearing assemblies are used as rail car bearings assembled onto journals at the ends of the car axles. Bearings of this type typically employ two rows of tapered roller bearings fitted one into each end of a common bearing cup with their respective bearing cones having an inner diameter dimensioned to provide an interference fit with the shaft journal and with a cylindrical sleeve or spacer positioned between the cones providing accurate spacing and proper lateral clearance on the journal. Seals mounted within each end of the bearing cup provide sealing contact with wear rings bearing against the outer ends or back face of the respective bearing cones at each end of the assembly. Such seals are shown in U.S. Pat. No. 5,975,533. 
         [0002]    In a typical rail car installation, the axle journal is machined with a fillet at the inboard end, and a backing ring having a surface complementary to the contour of the fillet and an abutment surface for engaging the inboard end of the inner wear ring accurately positions the bearing assembly on the journal. An end cap mounted on the end of the axle by bolts threaded into bores in the end of the axle engages the outboard wear ring and clamps the entire assembly on the end of the axle. The wear rings typically have an inner diameter dimensioned to provide an interference fit with the journal over at least a portion of their length so that the entire assembly is pressed as a unit onto the end of the journal shaft. 
       SUMMARY OF THE INVENTION 
       [0003]    The bearing assembly of the present invention is a roller bearing that includes an inner race or cone fitted around the journal portion of the axle or shaft. The inner race includes an outwardly directed raceway. An outer race or cup has an inwardly directed raceway. Roller elements are located between and contacting the inner and outer raceways. 
         [0004]    A backing ring has a contoured surface complementary to and engaging the contoured surface of a fillet formed on the shaft. The fillet leads from the journal to the shoulder of the shaft. The contoured surfaces cooperate to fix the backing ring against axial movement along the shaft. 
         [0005]    The bearing assembly includes a seal assembly that provides a barrier for lubricant to be retained within the seal assembly and for contaminants to be kept out. The seal assembly includes a stator apprised to the seal section itself and a rotor affixed to a wear ring. The inter-related relationship between the seal section, stator and rotor act to retain the lubricant within the seal assembly and to keep contaminants out. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    In the drawings, 
           [0007]      FIG. 1  is a sectional view of a shaft journal having mounted thereon a tapered roller bearing assembly in accordance with an embodiment of the present invention; 
           [0008]      FIG. 2  is a detailed partial view in cross section of a tapered roller bearing seal assembly in accordance with a first embodiment of the present invention, and 
           [0009]      FIG. 3  is a detailed view in partial cross section of a tapered roller bearing assembly in accordance with a second embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0010]    Referring now to  FIG. 1  of the drawings, a bearing assembly indicated generally by the reference numeral  10  on  FIG. 1  is shown mounted on a journal  12  on the free, cantilevered end of a shaft or axle  14 , typically a rail car axle. Journal  12  is machined to very close tolerances and terminates at its inner end in a contoured fillet  22  leading to a cylindrical shoulder  18  of axle  14 . At the free end of the axle, journal portion  12  terminates in a slightly conical or tapered guide portion  24  dimensioned to facilitate installation of the bearing assembly onto the journal. A plurality of threaded bores  26  are formed in the end of axle  14  for receiving threaded cap screws, or bolts  28  for mounting a bearing retaining cap  30  on the end of the shaft to clamp the bearing in position as described more fully herein below. 
         [0011]    The bearing assembly  10  is preassembled before being mounted and clamped on journal  12  by cap  30  and bolts  28 . The bearing assembly includes a unitary bearing cup or outer raceway  32  having a pair of raceways  34 ,  36  formed one adjacent each end thereof which cooperate with a pair of bearing cones  38 ,  40 , respectively, to support the two rows of tapered rollers  42 ,  44 , respectively, therebetween. A center spacer  46  is positioned between cones  38 ,  40  to maintain the cones in accurately spaced position relative to one another allowing for proper bearing lateral clearance. 
         [0012]    The bearing cup  32  is provided with cylindrical counterbores  17 , 19  at its opposite ends outward of the raceways  34 ,  36 , and a pair of seal sections  52 ,  58  are pressed one into each of the cylindrical counterbores  17 , 19  in cup  32 . Each seal section  52 ,  58  includes resilient sealing elements which rub upon and form a seal with surfaces  37 , 61  of a pair of seal wear rings  60 ,  62 , having an inwardly directed end in engagement with the outwardly directed ends of bearing cones  38 ,  40 , respectively. Seal section  58  is similar to seal section  52  and will not be described in detail. The other end of wear ring  60  is received in a cylindrical counterbore  64  in the axially outwardly directed end of an annular backing ring  66  which, in turn, has a counterbore  68  at its other end which is dimensioned to be received in interference and non-interference relation on the cylindrical shoulder  18  of shaft  14 . The counterbore  64  and the outer diameter of wear ring  60  are also dimensioned to provide an interference fit so that wear ring  60  is pressed into the backing ring  66  which is accurately machined to provide a contoured inner surface  70  complementary to and engaging the contour of fillet  22  when the bearing is mounted on the shaft. The outwardly directed end of wear ring  62  bears against a counterbore  31  in retaining cap  30 . 
         [0013]    Referring now to  FIG. 2 , a detailed view of seal assembly portion of bearing assembly  10  is provided. Seal section  52  is seen to comprise a generally circular piece, having a larger diameter end section  48  pressed or fit into a complementary counterbore  17  in cup  32 . Seal section  52  includes a main cylindrical section  53  that extends parallel to end section  48 , wherein main cylindrical section  53  has a smaller diameter than end section  48 . 
         [0014]    An inner circular section  54  is normal to main cylindrical section  53  and extends inwardly toward wear ring  60 . Distal end  55  of seal section  52  extends from inner circular section  54  at an acute angle thereto. Resilient sealing element  57  is fitted onto distal end  55 . Resilient sealing element  57  is comprised of a rubber or elastomer compound, such as Nitrile rubber compound. Resilient sealing element  57  includes a main section that includes an opening to receive distal end  55  of seal assembly  52 . Resilient sealing element  57  also includes base circular contact rib  59  that is laterally spaced from two base ribs  69 . Accordingly, a space exists between end contact rib  59  and base contact ribs  69 . 
         [0015]    A stator  47  is a generally cylindrical piece, having an outer section  49  of a larger diameter. The outer surface of outer section  49  is affixed by welding, gluing, dimpling, interference fit, or other appropriate method to an inner surface of main cylindrical section  53  of seal assembly  52 . Stator  47  also includes first intermediate section  51  that extends from outer section  49  parallel to section  54  of seal case  52 , second intermediate section  88  that extends at an acute angle from first intermediate section  51 , and inner section  90  that extends from second intermediate section  88 . Note that in the preferred embodiment of  FIG. 2 , first intermediate section  51  of stator  47  is adjacent inner cylindrical section  54  of seal section case  52 . Second intermediate section  88  is also seen to pass adjacent a complimentary shaped section of resilient sealing element  57 . A third intermediate section  89  is present in stator  47 ; third intermediate section  89  is stepped from second intermediate section  88  to inner section  90  and assists in ease of assembly. Inner section  90  of stator  47  is seen to extend parallel to outer surface  37  of wear ring  60 . Inner section  90  is seen to end at end section  92 . 
         [0016]    Rotor  81  is seen to be a generally cylindrical piece having an outer section  82  of a larger diameter. Intermediate section  83  extends from outer section  82  and is generally normal thereto. Intermediate section  83  includes a generally flat outer section  93  that is fitted against a complementary flat surface  94  of bearing cone  38 . Inner section  84  of rotor  81  extends from intermediate section  83  and is generally normal thereto. Inner section  84  of rotor  81  has an outer surface  95  which is fitted against outer surface  37  of wear ring  60 . 
         [0017]    Outer surface  95  of rotor  81  is welded, glued, or interference fitted to outer surface  37  of wear ring  60 . A bead or rib  97  or other affixing media can be located at inner section  84  of rotor  81  to affix to outer surface  37  of wear ring  60 . Chamfer  98  in outer surface  37  of wear ring  60  aids the bead or rib  97  with location to outer surface  37 . The combination and configuration of seal section  52 , stator  47  and rotor  81  assist in retaining lubricant within the seal assembly. As rotor  81  inner section  84  and outer section  82  rotate about stator  47  inner section  90 , the path required for lubricant to escape from within the seal assembly is torturous. Preferably, stator  47  inner section  90  extends a minimum of about halfway into the channel formed by rotor outer section  82  and inner section  84 , but such extension could be from 25% to 75% or more. The presence of resilient sealing element  57  further restricts the lubricant from exiting the seal assembly. The preferred spacing between rotor  81  section  84  and stator  47  section  90  is a nominal 0.030 inch and between stator  47  section  90  and rotor  81  outer section  82  is a nominal 0.030 inch. It should be understood that seal section  52  itself is normally comprised of a suitable steel, as are rotor  81  and stator  47 . However, it is within the scope of the present invention to have one or more of seal section  52 , rotor  81  or stator  47  comprised of an engineered plastic polymer or thermoplastic such as polyester or composite material. 
         [0018]    Referring now to  FIG. 3 . a detailed view of a second embodiment of a seal assembly portion of bearing assembly  110  is provided. Seal section  152  is seen to comprise a generally circular piece, having a larger diameter end section  148  pressed or fit into a complementary counterbore  117  in cup  132 . Seal section  152  includes a main cylindrical section  153  that extends parallel to end section  148 , wherein main cylindrical section  153  has a smaller diameter than end section  148 . 
         [0019]    An inner circular section  154  is normal to main cylindrical section  153  and extends inwardly toward wear ring  160 . Angled section  155  of seal section  152  extends from inner circular section  154  at an acute angle thereto. Resilient sealing element  157  is fitted onto protrusion  158  of angled section  155 . Resilient sealing element  157  is comprised of a rubber or elastomer compound, such as Nitrile rubber compound. Resilient sealing element  157  includes a main section that includes an opening to receive protrusion  158  of seal assembly  152 . Resilient sealing element  157  also includes base circular contact rib  159  that is laterally spaced from two base ribs  169 . Accordingly, a space exists between end contact rib  159  and base contact ribs  169 . 
         [0020]    A stator section  147  is a generally cylindrical piece, having an outer section  149  with an indented surface. The stator section  147  extends from angled section  155  of seal case  152  and is formed in the same process or operation. 
         [0021]    Rotor  181  is seen to be a generally cylindrical piece having an outer section  182  of a larger diameter. Intermediate section  183  extends from outer section  182  and is generally normal thereto. Intermediate section  183  includes a generally flat outer section  193  that is fitted against a complementary flat surface  194  of bearing cone  138 . Inner section  184  of rotor  181  extends from intermediate section  183  and is generally normal thereto. Inner section  184  of rotor  181  has an outer surface  195  which is fitted against outer surface  137  of wear ring  160 . 
         [0022]    Outer surface  195  of rotor  181  is welded, glued, or interference fitted to outer surface  137  of wear ring  160 . A bead or rib  197  or other affixing media can be located at a corner between intermediate section  183  of rotor  181  and outer surface  195  of inner section  184  of rotor  181  to affix to outer surface  137  of wear ring  160 . Chamfer  198  in outer surface  137  of wear ring  160  aids the bead or rib  197  with location to outer surface  137 . 
         [0023]    The combination and configuration of seal section  152 , including stator section  147  and rotor  181  assist in retaining lubricant within the seal assembly. As rotor  181  inner section  184  and outer section  182  rotate about stator  147  outer section  149 , the path required for lubricant to escape from within the seal assembly is torturous. Preferably, stator  147  outer section  149  extends about halfway into the channel formed by rotor outer section  182  and inner section  184 , but such extension could be from 25% to 75% or more. The presence of resilient sealing element  157  further restricts the lubricant from exiting the seal assembly. The preferred spacing between rotor  181  section  184  and stator  147  outer section  149  is nominal 0.030 inch and between stator  147  outer section  149  and rotor  181  outer section  182  is a nominal 0.030 inch. It should be understood that seal case  152  itself is normally comprised of suitable steel, as are rotor  181 . However, it is within the scope of the present invention to have one or more of seal section  152 , rotor  181  comprised of an engineered thermoplastic such as polyester or composite material. 
         [0024]    It should be understood that seal section  152  and stator  147  can be a unitary component.