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, and includes a rotor, a seal, a slinger and, in some embodiments, a stator.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to sealed shaft journal bearings and, more particularly, to an improved tapered roller 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. Nos. 5,975,533 and 7,607,836. 
     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 
     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. 
     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. 
     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 may include a stator adjacent to the seal section itself and a rotor adjacent to a wear ring. A slinger having a section adjacent the wear ring is also provided. The inter-related relationship between the seal section, stator, rotor and slinger act to retain the lubricant within the seal assembly and to keep contaminants out. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         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; 
         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; 
         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; and 
         FIG. 4  is a detailed view in partial cross section of a tapered roller bearing assembly in accordance with a third embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     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. 
     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 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 . 
     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 cylindrical piece, having a larger diameter first end section  48  pressed or fit into a complementary counterbore  17  in cup  32 . Seal section  52  includes an intermediate section  53  that extends parallel to first end section  48 , and a second end section  54  extending from intermediate section  53  and parallel to first end section  48 . Portion  55  of intermediate section  53  is normal to intermediate section  53 . 
     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 . Slinger  112  is a generally cylindrical structure usually comprised of steel or a polymer plastic. Slinger  112  includes a first end section  114 , an intermediate section  116  normal to first end section  114  and a second end section  118  normal to intermediate section  116 . First end section  114  is of a greater diameter than second end section  118 . First end section  114  is located adjacent to and radially outside of intermediate section  53  of seal  52 . Intermediate section  116  is located adjacent and radially inside of seal portion  55 . Second end section  118  includes an outer surface that is adjacent to and abutting against outer surface  37  of wear ring  60 . 
     Outer surface  95  of rotor inner section  84  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 relation to outer surface  37 . The combination and configuration of seal section  52 , slinger  112 , rotor  81  assist in retaining lubricant within the seal assembly. As rotor  81 , inner section  84 , and outer section  82  rotate about seal second end section  54 , the path required for lubricant to escape from within the seal assembly is torturous. Preferably, seal second end section  54  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. It should be understood that seal  52  itself is normally comprised of a suitable steel, as are rotor  81 , stator  47  and slinger  112 . However, it is within the scope of the present invention to have one or more of seal  52 , rotor  81  or slinger  112  comprised of an engineered plastic polymer or thermoplastic such as a polyester or composite material. 
     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 cylindrical piece, having first end section  148  pressed or fit into a complementary counterbore  117  in cup  132 . Seal section  152  includes an intermediate section  153  that extends normal to first end section  148 , and second end section  155  has a smaller diameter than first end section  148 , and is parallel therewith. 
     A stator  147  is a generally cylindrical piece, having a first end section  149  having an outer surface  159  adjacent and affixed to an inner surface  157  of second end section  155  of seal  152 . Stator  147  also includes intermediate section  161  that is normal to first end section  149  and a second end section  151  that is normal to intermediate section  161 . 
     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 . 
     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 . 
     Slinger  212  is a generally cylindrical structure usually comprised of steel or a polymer plastic. Slinger  212  includes a first end section  214 , an intermediate section  216  normal to first end section  214  and a second end section  218  normal to intermediate section  216 . First end section  214  of a greater diameter than second end section  218  and is located adjacent to and radially outside second end section  155  of seal  152 . Intermediate section  216  is located adjacent and radially inside of stator intermediate section  161 . Second end section  218  includes an outer surface that is adjacent to and abutting against outer surface  137  of wear ring  160 . 
     The combination and configuration of seal section  152 , including stator section  147  slinger  212  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  second end section  151 , the path required for lubricant to escape from within the seal assembly is torturous. Preferably, stator  147  second end section  151  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. It should be understood that seal case  152  itself is normally comprised of suitable steel, as are rotor  181 , stator  147  and slinger  212 . However, it is within the scope of the present invention to have one or more of seal section  152 , rotor  181 , stator  147  and slinger  212  comprised of an engineered thermoplastic such as polyester or composite material. 
     Referring now to  FIG. 4  a detailed view of a third embodiment of a seal assembly portion of bearing assembly  210  is provided. Seal section  352  is seen to comprise a generally cylindrical piece, having first end section  348  pressed or fit into a complementary counterbore  317  in cup  332 . Seal section  352  includes an intermediate section  355  that extends normal to first end section  348 , and second end section  353  has a smaller diameter than first end section  348 , and is parallel there with. 
     A stator  347  is a generally cylindrical piece, having a first end section  349  having an outer surface  359  adjacent and affixed to an inner surface  357  of second end section  353  of seal  352 . Stator  347  also includes intermediate section  361  that extend from first end section  349  and a second end section  351  that extends from intermediate section  361 . 
     Rotor  381  is seen to be a generally cylindrical piece having an outer section  382  of a larger diameter. Intermediate section  383  extends from outer section  382  and is generally normal thereto. Intermediate section  383  includes a generally flat outer section  393  that is fitted against a complementary flat surface  394  of bearing cone  338 . Inner section  384  of rotor  381  extends from intermediate section  383  and is generally normal thereto. Inner section  384  of rotor  381  has an outer surface  395  which is fitted against outer surface  337  of wear ring  360 . 
     Outer surface  395  of rotor  381  is welded, glued, or interference fitted to outer surface  337  of wear ring  360 . A bead or rib  397  or other affixing media can be located at a corner between intermediate section  383  of rotor  381  and outer surface  395  of inner section  384  of rotor  381  to affix to outer surface  337  of wear ring  360 . Chamfer  398  in outer surface  337  of wear ring  360  aids the bead or rib  397  with location to outer surface  337 . 
     Slinger  312  is a generally cylindrical structure usually comprised of steel or polymer plastic. Slinger  312  includes a first end section  314 , an intermediate section  316  normal to first end section  314  and a second end section  318  normal to intermediate section  316 . First end section  314  of a greater diameter than second end section  318  and is located adjacent to and radially outside intermediate section  355  of seal  352 . Intermediate section  316  is located adjacent and laterally inside of seal second end section  353 . Second end section  318  includes an outer surface that is adjacent to and abutting against outer surface  337  of wear ring  360 . 
     The combination and configuration of seal section  352 , including stator section  347 , slinger  312  and rotor  381  assist in retaining lubricant within the seal assembly. As rotor  381 , inner section  384 , and outer section  382  rotate about stator  347  second end section  351 , the path required for lubricant to escape from within the seal assembly is torturous. Preferably, stator  347  second end section  331  extends about halfway into the channel formed by rotor outer section  382  and inner section  384 , but such extension could be from 25% to 75% or more. It should be understood that seal case  352  itself is normally comprised of suitable steel, as are rotor  381 , stator  347  and slinger  312 . However, it is within the scope of the present invention to have one or more of seal section  352 , rotor  381 , stator  347  and sling  312  comprised of an engineered thermoplastic such as polyester or composite material.