Patent Publication Number: US-6908230-B2

Title: Shaft locking device for bearing assemblies

Description:
This is a divisional application of U.S. patent application Ser. No. 09/235,691, filed Jan. 22, 1999, now U.S. Pat. No. 6,200,039, which is a divisional application of U.S. application Ser. No. 08/798,284, filed on Feb. 7, 1997, now U.S. Pat. No. 5,863,137. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to bearing assemblies, and more particularly, to a bearing assembly having improved means for securing the inner bearing ring of the assembly onto a shaft. 
     BACKGROUND OF THE INVENTION 
     Various arrangements are known in the art for securing the inner bearing ring of a bearing assembly onto a rotating shaft. Such arrangements have included shaft engaging set screws and shaft-surrounding locking collars. Such locking collars include locking or tightening means, generally in the form of one or more locking screws. In the so-called SKWEZLOC® arrangement disclosed in U.S. Pat. Nos. 4,537,519 and 4,728,203, the inner ring has finger extensions which, when compressed with a screw operated locking collar, tightly grip and hold the shaft. This finger extension/locking collar combination enhances the concentricity of the inner ring with the shaft and facilitates rotation of the shaft at higher speeds. 
     Arrangements which utilize shaft-surrounding locking collars, however, have various shortcomings. Inasmuch as the locking collar is a separate component from the inner bearing ring, the locking collar can become separated from the bearing assembly and lost or mislaid. Moreover, if the locking collar is not properly disposed on the inner bearing ring during assembly, the collar may not adequately secure the inner bearing ring to the shaft. For example, if the collar is slightly cocked on the inner bearing as it is tightened, it will align itself after the shaft is rotated. This causes the collar to become loose on the inner bearing, resulting in slippage between the inner bearing ring and the shaft when subjected to radial and/or axial loads. The problems of mounting and retaining such locking collars are compounded if the collar comprises a multiplicity of segments which must be properly positioned and tightened during installation. 
     SUMMARY OF THE INVENTION 
     In overcoming these problems with the prior art there is provided a bearing assembly wherein the locking collar may be efficiently pre-assembled on the inner bearing ring at the factory and remain properly positioned on the inner bearing ring during installation onto a shaft. In this way, the collar may not be readily separated from the bearing assembly and mislaid. Moreover, this preassembly ensures that the collar is in proper position on the inner bearing ring which facilitates subsequent reliable installation of the collar and inner bearing ring on the shaft. 
     In accomplishing these objectives, the inner diameter of the compressible annular locking collar is provided with a protrusion which extends radially inwardly. When the locking collar is disposed about the finger extensions of the inner ring, the protrusion is disposed within a recessed groove which extends at least partially along the collective outer annular surface defined by the finger extensions for precisely locating and orienting the collar. According to a feature of the invention, when the inner ring finger extensions and the locking collar are in their free states, the inner diameter of the protrusion is slightly smaller than the outer diameter of the finger extension groove. In this way, the collar may be snapped over the finger extensions and into proper position on the inner ring prior to installation on a shaft, i.e., in the factory. The locking collar then remains in proper position on the finger extensions as the bearing assembly subsequently is installed onto the shaft. In one embodiment, a one-piece locking collar body has an integrally formed protrusion adapted for snap action engagement with a finger extension recess, in another embodiment the locking collar has separate resilient O-ring engageable with the finger extension recess, and in another embodiment, the locking collar and finger extensions are formed with screws which permit threaded advancement of the locking collar into preassembled position. In each case, following preassembly of the bearing assembly an a shaft, a locking screw may thereafter be tightened to deform the finger extensions into secure engagement with the shaft. 
     These and other features and advantages of the invention will be more readily apparent upon reading the following description of preferred exemplified embodiments of the invention and upon reference to the accompanying drawings wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective of a bearing assembly in accordance with the present invention; 
         FIG. 2  is an enlarged side elevational view of the bearing assembly shown in  FIG. 1 , partially cut away; 
         FIG. 3  is a enlarged fragmentary section of a portion of the bearing assembly of  FIGS. 1 and 2 , showing the relative position of the inner ring finger extensions and the locking collar as the latter is snapped over the ring extensions; 
         FIG. 4  is a view similar to  FIG. 3  showing the relative position of the ring finger extensions and locking collar upon tightening of the collar; 
         FIG. 5  is an enlarged cross sectional view of a portion of a bearing assembly according to a second embodiment of the invention; 
         FIG. 6  is an enlarged cross sectional view of a portion of a bearing assembly according to a third embodiment of the invention; 
         FIG. 7  is a plan view of the locking collar shown in FIG.  6 . 
         FIG. 8  is a fragmentary section of an alternative locking collar mounting and retaining arrangement according to the present invention; 
         FIG. 9  is an enlarged fragmentary section of the locking collar and inner bearing ring shown in  FIG. 8 ; 
         FIG. 10  is still another alternative locking collar mounting and retaining arrangement; and 
         FIG. 11  is an exploded view of the locking collar and inner bearing ring shown in FIG.  10 . 
     
    
    
     While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now more particularly to  FIGS. 1 and 2  of the drawings, there is shown an illustrative bearing assembly  10  embodying the present invention mounted on a shaft  12  (shown in phantom). The bearing assembly  10  includes an annular inner ring  14  having a grooved raceway  16  formed in a main body portion  15  thereof. Surrounding the inner ring  14  in spaced relation thereto is an annular outer ring  18  having a grooved raceway  20  disposed in opposed relationship to the inner raceway  16 , the raceways  16 ,  20  serving to receive in nesting relationship a plurality of spaced balls or rolling elements  22 . The rolling elements  22  in this case are disposed in rolling element pockets of a conventional cage  24 . Preferably, the inner and outer raceways are wear hardened for extending the life of the bearing. 
     While not illustrated in the drawings, the assembly  10  includes a convention means for lubricating movement of the rolling elements  22 . To maintain lubrication to the rolling elements  22 , the space between the inner and outer bearing rings  14 ,  18  is sealed by annular inner and outer flingers  26 ,  28  with annular seals  30  therebetween. The inner and outer flingers  26 ,  28  are press-fitted on the inner and outer bearing rings  14 ,  18 , respectively, on either side of rolling element cage  22 . 
     To facilitate mounting of the bearing assembly  10  to the shaft  12 , the inner bearing ring  14  is provided with a compressible annular portion  32  having a reduced diameter and which extends from the main body portion  15 . To maximize radial compression of the extended annular portion  32 , the portion  32  is preferably provided with a plurality of axial slots  34  which define a plurality of finger-like extensions  36  from a shoulder  38  of the main body portion  15  of inner ring  14 . The slots  34  preferably are parallel to the axis of rotation of the shaft  12  to provide the most desirable attachment and performance characteristics. 
     The finger extensions  36  in this case are formed with an area of reduced thickness defined by a groove or recess  39  which extends annularly around the outer periphery of the finger extensions  36 . This area of reduced thickness or bending groove  39 , which is spaced axially inwardly from the distal ends of the finger extensions  36 , permits a slight bending of the finger extensions  36  to facilitate securing the inner ring  14  to the shaft  12 , as disclosed in U.S. Pat. No. 4,537,519. The groove  39  in this case defines raised lip  41  having an outer cylindrical surface  45  at the ends of the finger extensions  36 . 
     For securing the bearing assembly  10  on the shaft  12 , a one piece locking collar  40  is concentrically disposed about the extended annular portion  32 . To permit tightening of the locking collar  40  about the shaft  12 , a locking screw  42  is threaded tangentially through the collar  40  normal to a slot or gap  43  between the ends of the collar. The screw  42  is recessed into the locking collar  40  and preferably receives an hexagonal wrench (not shown). It will be appreciated that, by tightening the screw  42 , the ends of the locking collar  40  at the slot or gap  43  (see  FIG. 1 ) are drawn toward one another to effectively reduce the inner diameter of the collar  40  and to radially compress the finger extensions  36  of the inner ring  14  into secure engagement with the shaft  12 . 
     To facilitate proper positioning and alignment of the collar  40  onto the inner ring  14 , the breadth of collar  40  is preferably substantially equal or, as shown in the embodiments illustrated, slightly larger than the length of the finger extensions  36  to ensure that optimum locking force will be applied to the finger extensions  36 . The breadth of the bending groove  39  in the finger extensions  36  preferably is on the order of one half the length of the finger extensions  36  to one half the breadth of the locking collar  40 . 
     The collar  40  may be properly aligned or “squared” by exerting a force on an outer side of the collar  40  to ensure that the collar  40  is fully seated against the shoulder  38  of the inner ring  14 . In this way, one can visually determine if the collar  40  and the distal ends of the finger extensions  36  are in the appropriate physical relationship. It will be appreciated by one skilled in the art that if the screw  42  is tightened when the collar  40  is not yet fully or properly seated on the inner ring, the collar  40  may become loose during rotation of the shaft. As a result, when the collar  40  eventually seats itself during use, the collar  40  will no longer provide the required locking force. 
     In accordance with the invention, the locking collar  40  has an inwardly directed protrusion adapted for locating and positively retaining the locking collar in properly oriented mounted position on the inner bearing ring for reliable long term usage. To this end, in the illustrated embodiment, as shown in  FIGS. 3 and 4 , the locking collar has an inner cylindrical mounting surface  46  adapted for mounting on the cylindrical surface  45  of the finger extension lips  41  and an integrally formed inwardly directed wedge shaped protrusion  50  which defines a locking ledge  51  and an inclined camming surface  52  which tapers radially outwardly from the ledge  51 . The distance between the locking ledge  51  and the axial side of the clamping collar  40  positioned against inner ring shoulder  38  corresponds substantially to the axial length of the groove  39  such that upon positioning of the protrusion into the groove  39 , the collar  40  is precisely located and retained within the groove  39  between the shoulder  38  of the inner bearing ring and the upturned lips  41  of the finger extensions  36 . Hence, the groove  39  in this case serves a dual function as a weakening recess for the finger extensions and a lock receiving and orienting groove for the collar  40 . 
     In keeping with the invention, the locking collar  40  is adapted for efficient snap action preliminary factory assembly onto the inner ring  14 . To this end, the protrusion  50  of the clamping collar  40  has an inner diameter that is slightly less than the outer diameter of the finger extension lips  41 . In order to assemble the collar  40 , it is first positioned into slightly surrounding relation to the finger extension lip  41 . To this end, a lead edge  58  of the camming surface  52  is slightly larger than the outer diameter of the finger extension lips  41 . The collar  40  may then be advanced onto the finger extensions  36 , with the angled or camming surface  52  of the protrusion advancing along the finger extensions  36  slightly flexing the fingers in an inward direction and the collar outwardly. As the protrusion  50  moves past the finger extension lip  41 , the finger extensions  36  and the locking collar  40  return or “snap back” to their original conditions, as shown in  FIG. 3 , automatically locating and orienting the locking collar  40  in position on the inner ring and positively preventing its removal. 
     In this way, the bearing assembly  10  may be preassembled in the factory and shipped to a customer or installation site with the collar  40  properly oriented. When the bearing assembly  10  is subsequently mounted on a shaft, the locking collar screw  42  simply may be tightened to securely lock the assembly on the shaft, essentially eliminating the possibility of misplacing the collar  40  during handling or incorrectly positioning the collar onto the inner bearing ring during installation. It will be appreciated that while in the embodiment of  FIGS. 1-4 , the protrusion  50  and the recess  39  extend circumferentially completely around the locking collar  50  and inner ring  14 , alternatively, the protrusions and recesses may be provided at circumferentially spaced locations. 
     Referring now to  FIG. 5 , there is shown an alternative embodiment of the invention wherein items similar to those described above having similar reference numerals with the distinguishing suffix “a” added. In this embodiment, the outer cylindrical surface  45   a , defined the finger extension lips  41   a , and the inner cylindrical mounting surface  46   a  of the collar  40   a  are formed with cooperating detents for releasable snap action inter-engagement and alignment of the components during assembly. In this instance, the inner cylindrical surface  46   a  of the collar  40   a  is formed with an outwardly rounded or arcuate-shaped protrusion  50   a  and the outer surface  45   a  of the lips  41   a  is formed with a complimentary shaped recess  60  for receiving the protrusion  50   a.    
     The protrusion  50   a  preferably is located at a distance from the side of the collar which seats against the inner ring shoulder  38   a  corresponding substantially to the distance of the recess  60  from the shoulder  38   a . The protrusion  50   a  of the collar  40   a  again has an inner diameter that is less than the diameter of the finger extension lips  41   a  with the curved configuration of the arcuate-shaped protrusion  50   a  serving to cam and force the finger extensions  36   a  and collar  40   a  apart during assembly to facilitate snap action engagement therebetween when the collar  40   a  is properly seated on the inner ring  14   a  against the shoulder  38   a . Again, preliminary factory assembly of the locking collar  40   a  may be efficiently effected with the collar being properly located in mounted position for final tightening upon subsequent installation of the bearing assembly  10   a  on a shaft. 
     Referring now to  FIGS. 6 and 7 , still another embodiment of the invention is shown, wherein items similar to those described above have been given similar reference numerals with the distinguishing suffix “b” added. In this embodiment, the collar  40   b  has a generally V-shaped protrusion  50   b  disposed at the juncture of inner cylindrical surfaces  46   b ,  60  of the collar  40   b . The protrusion  50   b  again has a smaller internal diameter than the lips  41   b  of the finger extensions  36   b  and is forced onto the finger extensions  36   b  and into the groove  39   b  with snap action engagement. The inner cylindrical surfaces  46   b ,  58   b  of the collar  40   b  on opposite sides of the protrusion  50   b  have different diameters so as to both be in close relationship with the cylindrical surface  45   b  of the finger extension lips  41   b  and the bottom surface of the groove  39   b , respectively. 
     In contrast to the first and second embodiments of the invention, in this embodiment the protrusion  50   b  does not extend-around the entire inner annular surface of the collar  40   b , but rather, only at discreet points, as shown in FIG.  6 . It will be appreciated, however, that the interference between the collar  40   b  and the finger extensions  36   b  at these discrete points, which are preferably symmetrically disposed, is sufficient to retain the components together. 
     Referring now to  FIGS. 8-9 , there is shown another embodiment of the invention wherein items similar to those described above have been given similar reference numerals with the distinguishing suffix “c” added. In this embodiment, the protrusion of the locking collar  40   c  is defined by a separate annular resilient member  55  carried within the annular opening of the locking collar  40   c . The illustrated annular resilient member  55  is an O-ring disposed within a rectangular groove  56  formed in the inner cylindrical surface  46   c  of the locking collar and sized so that a portion of the O-ring extends radially inwardly beyond the annular surface  46   c  to form a resilient protrusion. The cylindrical inner surface  46   c  of the locking collar preferably is only slightly larger than the outer diameter of the finger extension lips  41   c  such that upon positioning of the locking collar  40   c  onto the finger extensions  36   c  the O-ring  55  is forced substantially into the groove  56  and contained therein until reaching the recess or groove  39   c  of the finger extensions  36   c  at which time the O-ring  55  will snap into the recess for locating and retaining the locking collar  40   c  in preassembled position adjacent the inner ring shoulder  38   c . The distance between side of the locking collar positionable against the inner ring shoulder  38   c  and the locking collar groove  56  corresponds substantially to the axial length of the finger extension groove  39   c  such that upon snap action engagement of the O-ring  55  into the groove  39   c  the locking collar  40   c  is located against the shoulder  38   c . Following such preassembly of the locking collar  40   c , the locking screw  42   c  can be tightened to deform the finger extensions  36   c  into secure engaging relationship with the shaft upon which it is mounted. 
     Referring now to  FIGS. 10-11  still another alternative embodiment of bearing assembly is shown wherein items similar to those described above have been given similar reference numerals with the distinguishing suffix “d” added. In this embodiment, the inner cylindrical surface of the locking collar  40   d  and the outer surface of the finger extensions  36   d  are formed with cooperating threads  62 ,  63 , respectively, which enable the locking collar  40   d  to be rotatably threaded onto the finger extensions  36   d  until reaching its preassembly position in abutting relation with the inner ring shoulder  38   d . The threads  62 ,  63  in this case form protrusions which retain the locking collar  40   d  in preassembled position. Again, following such preassembly, tightening of the locking screw  42   d  will deform the finger extensions into secure engagement with the shaft upon which the bearing assembly is mounted. 
     In summary, it will be seen from the foregoing that the invention provides a unique bearing assembly locking arrangement wherein the locking collar may be preassembled onto the inner bearing ring in the factory. The locking collar is provided with a protrusion along its inner annular surface, and the finger extensions of the inner ring are provided with a mating groove. Both the groove and the protrusion may be of various sizes and shapes, extending completely or partially along the annular surface, so long as the groove and protrusion are relatively sized so that there is an interference between the components when in their free state. In this way, when the collar is preassembled onto the inner bearing ring, the collar is held in the proper position for subsequent installation and tightening onto a shaft.