Patent Publication Number: US-6988832-B2

Title: Bearing insert with controlled endplay

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of rotating machinery, and more particularly, to arrangements for securing a shaft or similar rotating member in a hollow support member, such as a bearing assembly. 
     A wide range of rotating machinery is known and currently in use in industrial and other applications. In many such applications shafts or hubs are supported for rotation within hollow members, such as bearings and other mechanical supports. The shaft or hub may be driven in rotation by a prime mover, such as an electric motor or engine, or may be linked to various power transmission elements such as chain drives, belt drives, transmissions, pulleys, and so forth. In all such applications, mounting structures are typically required to support the rotating and non-rotating members with respect to one another in a manner sufficient to resist loading, while still allowing for free rotation of the rotating members. 
     When mounting rotating elements on or within bearings, several key considerations generally come into play. For example, the bearing and associated coupling or mounting structures must be capable of withstanding the anticipated loads of the application. Moreover, the mounting structures should allow for the desired balancing or centering of loads within or about the bearing assemblies. Also, the mounting arrangements should prevent premature wear or fretting of the shaft or other mounting components, and thus provide for a maximum life in normal use. Finally, the mounting structures would ideally be relatively straightforward in application, permitting the shaft or hub and bearing assemblies to be installed without undue expense, both in terms of time and parts. The latter concern extends to dismounting or disassembling the various components for servicing and replacement when necessary. 
     Although mounting structures have been developed that address these concerns, further improvement is necessary. For example, various tapered locking structures have been developed that force tapered members between a shaft and a mounting hub or bearing. A wide range of structures have been developed to force a tapered sleeve, for example, into engagement between a hollow member and a shaft. Such structures provide good mechanical support and allow for tight engagement of the hollow member and shaft. In certain known arrangements, the foregoing structures are incapable of accommodating system expansion or misalignment, thereby increasing the wear and eventually damaging a bearing assembly, a tapered sleeve, and other associated components of the system. Existing mounting components also can be expensive to manufacture and difficult to assembly and disassemble. 
     There is a need, therefore, for an improved system for mounting a shaft or similar mechanical component within a hollow member. There is a particular need for a straightforward and reliable system for supporting tapered rollers in a bearing assembly with a desired bearing clearance. A need also exists for a bearing assembly capable of accommodating system expansion and misalignment. 
     SUMMARY OF THE INVENTION 
     A system and method is provided to accommodate positional variations in a bearing assembly, which has a clearance adjustment assembly for setting the roller clearance therein. The bearing assembly has multiple rows of tapered rollers disposed circumferentially between an inner sleeve and the clearance adjustment assembly, which is secured by an outer retaining sleeve. The clearance adjustment assembly has at least one clearance adjustment ring disposed adjacent multiple tapered support rings, which extend circumferentially about the multiple rows of tapered rollers. In the bearing assembly, the at least one clearance adjustment ring forces the multiple tapered support rings against the multiple rows of tapered rollers to set the desired roller clearance. The bearing assembly also may have seals disposed between the inner sleeve and the outer retaining sleeve at opposite sides of the multiple rows of tapered rollers. In operation, the inner sleeve is mountable to a rotatable member, while the outer retaining sleeve is insertable into a desired bearing mount. For example, the inner sleeve may have a screw mount assembly or an adapter mount assembly, such as a compressive fit mechanism. The outer retaining sleeve may be secured within the desired bearing mount via retaining structures disposed about the outer retaining sleeve at a desired spacing, such as a spacing providing a desired range of longitudinal movement. The desired bearing mount also may have a spherical outer structure, which is pivotally mountable in a spherical mount chamber. Accordingly, the bearing assembly can accommodate expansion, contraction, and angular variations in the system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a perspective view of an exemplary bearing system of the present technique, illustrated as a bearing assembly disposed about a shaft; 
         FIG. 2  is a partial sectional view of the bearing system of  FIG. 1 , illustrating an exemplary embodiment of the bearing assembly having a screw mount assembly; 
         FIG. 3  is a partial sectional view of the bearing system of  FIG. 1 , illustrating an alternative embodiment of the bearing assembly having an adapter mount assembly; 
         FIG. 4  is an elevational view of a locking member or nut as used in the system of  FIG. 3 , illustrating the eccentric aperture and varying depth groove used for mounting and operating the nut for engagement and disengagement of the system; 
         FIG. 5  is a side sectional view of the nut of  FIG. 4 , illustrating various surfaces and features of the nut; 
         FIG. 6  is a detail view of interfacing surfaces of the nut and hollow member of  FIG. 3 ; 
         FIG. 7  is a partial sectional view of the bearing system of  FIG. 3 , illustrating the bearing assembly within a spherical housing; 
         FIG. 8  is a perspective view of the bearing assembly of  FIG. 7 , illustrating the bearing assembly inserted into a bearing mount assembly via insertion slots; 
         FIG. 9  is a perspective view of the bearing assembly of  FIG. 8 , illustrating the bearing assembly rotated to an operable position within the bearing mount assembly; and 
         FIG. 10  is a partial sectional view of the bearing system of  FIGS. 7–9 , illustrating the engagement of the various components with respect to one another. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Turning now to the drawings, and referring first to  FIG. 1 , a bearing system  10  is illustrated generally for securing a mechanical member within a hollow member. In the application illustrated in  FIG. 1 , the hollow member is part of a bearing assembly  12  secured on a shaft  14 . As will be appreciated by those skilled in the art, many such applications exist, typically for rotating machinery and power transmission applications. As noted above, it should be borne in mind that the system described herein may be applied in various settings, including for rotating and non-rotating applications. Moreover, while a shaft is shown and described herein, various types of mechanical elements may be employed with the present system, such as hubs, various support extensions, gearing, pinions, and so forth. Similarly, while as described herein bearing assembly  12  supports shaft  14  in rotation, in other applications, the central member, such as shaft  14  may be stationary with the bearing supporting other elements in rotation, such as in pulleys, conveyers and the like. The bearing assembly  12  also may comprise a variety of internal and external mount mechanisms, such as threaded fasteners, compressive fit mechanisms, pivotal or spherical joint mechanisms, and so forth. 
     As described in further detail below with reference to  FIGS. 2–3  and  7 – 10 , the bearing assembly  12  of the present technique also has an integral clearance control and support mechanism  16 . The mechanism  16  functions to set the clearance of tapered roller arrays  18  and  20 , which are disposed within the bearing assembly  12 . The tapered roller arrays  18  and  20  also may be factory sealed and lubricated within the integral clearance control and support mechanism  16  to facilitate simple and flexible mounting of the bearing assembly  12 . In the embodiment of  FIG. 2 , the bearing assembly  12  has a threaded fastener mechanism  22  to mount the bearing assembly  12  to the shaft  14 . In the embodiments of  FIGS. 3–10 , the bearing assembly  12  has an adapter or compressive fit mechanism  24  to mount the bearing assembly  12  to the shaft  14 . For external mounting, the bearing assembly  12  may have a cylindrical or spherical casing that is movingly insertable in a mount structure to accommodate system expansion and misalignment, such as illustrated in  FIGS. 7–10 . 
     As illustrated in  FIG. 2 , the bearing assembly  12  has the integral clearance control and support mechanism  16  disposed circumferentially about tapered roller arrays  18  and  20 , which are disposed in angled recesses  26  and  28  of inner sleeve  30 . The integral clearance control and support mechanism  16  may include tapered supports  32  and  34 , an intermediate clearance adjustment ring  36 , and an outer retaining sleeve  38 . The tapered supports  32  and  34  extend circumferentially around the respective tapered roller arrays  18  and  20  to hold the tapered roller arrays  18  and  20  in the respective angled recesses  26  and  28 . Given the angled relationship between the tapered supports  32  and  34  and the respective tapered roller arrays  18  and  20 , the wedged position of the tapered supports  32  and  34  controls the clearance or endplay of the tapered roller arrays  18  and  20  between the tapered supports  32  and  34  and the respective angled recesses  26  and  28 . Accordingly, the clearance adjustment ring  36  has dimensions, e.g., a width, selected to set the tapered supports  32  and  34  in a desired clearance position relative to the respective tapered roller arrays  18  and  20 . The outer retaining sleeve  38  is then secured about the tapered supports  32  and  34  and the intermediate clearance adjustment ring  36  to set the desired clearance. It should be noted that the integral clearance control and support mechanism  16  can use any suitable wedging mechanism to set the desired clearance of the tapered roller members  18  and  20 . Moreover, the roller members  18  and  20  may comprise any number or type of rotatable members, such as spherical members, cylindrical members, tapered cylindrical members, egg-shaped members, and so forth. 
     The bearing assembly  12  also may have seals  40  and  42  extending between the inner sleeve  30  and the outer retaining sleeve  38 , as illustrated in  FIG. 2 . The seals  40  and  42  may be integral with the inner sleeve  30 , integral with the outer sleeve  38 , integral with one another, or separately insertable to form a sealed enclosure  44  around the tapered roller arrays  18  and  20 . The bearing assembly  12  also may be lubricated through lubrication receptacles  46  and  48 , which extend through the outer retaining sleeve  38  and the clearance adjustment ring  36  and into the sealed enclosure  44 . Accordingly, the tapered roller members  18  and  20  may be factory set with a desired rolling clearance, factory sealed and lubricated, and then distributed as an integral bearing assembly  12 . Moreover, as mentioned above, the bearing assembly  12  is externally mountable in a movable manner, such that the bearing assembly  12  can accommodate system expansion and misalignment. 
     The bearing assembly  12  also may have a variety of mounting mechanisms. As illustrated in  FIG. 2 , the threaded fastener mechanism  22  can be used to mount the bearing assembly  12  to the shaft  14 . The illustrated threaded fastener mechanism  22  includes threaded fasteners  50  and  52 , which are insertable into threaded receptacles  54  and  56  of collars  58  and  60 , respectively. The collars  58  and  60  are positionable about opposite ends of the inner sleeve  30 , such that the threaded fasteners  50  and  52  may be rotated radially inwardly through the inner sleeve  30  via receptacles  62  and  64 . In operation, the threaded fasteners  50  and  52  exert a retaining force against the shaft  14  to secure the bearing assembly  12  to the shaft  14 . 
     Alternatively, the bearing assembly  12  can be mounted to the shaft  14  via the compressive fit mechanism  24 , as illustrated in  FIG. 3 . The bearing assembly  12  of  FIG. 3  has the integral clearance control and support mechanism  16  disposed circumferentially about the tapered roller arrays  18  and  20 . As illustrated, the tapered roller arrays  18  and  20  are disposed movably between the tapered supports  32  and  34  and bearing races  66  and  68  of the compressive fit mechanism  24 . The clearance adjustment ring  36  then sets the rolling clearance or endplay of the tapered roller arrays  18  and  20 . The clearance adjustment ring  36  has dimensions, e.g., a width, selected to set the tapered supports  32  and  34  in a desired clearance position relative to the respective tapered roller arrays  18  and  20 . The outer retaining sleeve  38  is then secured about the tapered supports  32  and  34  and the intermediate clearance adjustment ring  36  to set the desired clearance. The illustrated bearing assembly  12  also may have seals  40  and  42  and lubrication receptacles  46  and  48  to facilitate a sealed lubrication of the tapered roller arrays  18  and  20  inside the sealed enclosure  44 . Accordingly, the tapered roller members  18  and  20  may be factory set with a desired rolling clearance, factory sealed and lubricated, and then distributed as an integral bearing assembly  12 . 
     The compressive fit mechanism  24  illustrated in  FIG. 3  may comprise a variety of radially compressive mechanisms, such as a pair of concentric sleeves  70  and  72  wedgingly intercoupled via a threaded fastener  74 . As illustrated, the bearing races  66  and  68  of sleeve  70  support the tapered roller arrays  18  and  20 , while the sleeve  72  is mountable about the shaft  14 . In order to create a compressive force, at least one of the concentric sleeves  70  and  72  has a tapered geometry, which creates a wedging relationship between the concentric sleeves  70  and  72 . Moreover, at least one of the concentric sleeves  70  and  72  is threadingly coupled to the threaded fastener  74 , while the remaining sleeve is longitudinally movable with the threaded fastener  74 . Accordingly, the threaded fastener  74  forces the concentric sleeves  70  and  72  wedgingly toward one another, such that the inner sleeve  72  compresses about the shaft  14 . 
     In the illustrated embodiment, the sleeve  70  includes an outer annular groove  76  bounded by an annular lip  78 , which is adjacent a distal or end face  80  of the sleeve  70 . In operation, the end face  80  serves as an abutment surface between the sleeve  70  and the threaded fastener  74 , while the annular groove  76  and lip  78  are disposed in a mating lip  82  and groove  84  of the threaded fastener  74 . The threaded fastener  74  also has internal threads  86 , which are rotatably engageable with external threads  88  of the sleeve  72 . Accordingly, the threaded fastener  74  threadingly moves along the sleeve  72 , while forcing the sleeve  70  inwardly or outwardly from the sleeve  70 . It should be noted that various additional features not specifically illustrated in the figures may be included within the sleeve  72 . For example, slits extending partially are completely through the sleeve  72  may be provided to permit expansion or contraction of the sleeve  72  during tightening or loosening within the assembly. Similarly, such slits may accommodate keys, splines, or other mechanical features used to secure the various elements with respect to one another and to permit transmission of torque in application. 
     As best illustrated in  FIGS. 4 ,  5 , and  6 , the internal threads  86  of the threaded fastener  74  are designed for engagement on the external threads  88  of sleeve  72 . An aperture  90  (see, e.g.,  FIGS. 4 and 5 ) is formed eccentrically on a front face of threaded fastener  74 . The aperture  90  forms an opening larger than the diametrical dimension of lip  78  of sleeve  70 , such that the threaded fastener  74  may be slipped onto the lip  78  during assembly. Inside the eccentric aperture  90 , the lip  82  and groove  84  of the threaded fastener  74  have a varying depth attributed to the eccentricity of the aperture  90 . Accordingly, the sleeve  72  may be inserted into the aperture  90  due to the varying depth of the lip  82  and groove  84 , which can subsequently interlock with the respective groove  76  and lip  78  of the sleeve  72 . The eccentric aperture  90  also has an abutment face  92  that bounds the groove  84  on a side opposite the lip  82 . Finally, tool recesses  94  or similar structures are preferably provided to permit engagement of a tool (not shown) for tightening and loosening the threaded fastener  74  in the assembly. 
     Referring to  FIGS. 4 and 5 , the groove  84  and internal threads  86  of threaded fastener  74  have a common central axis  96 , which is generally the rotational axis of threaded fastener  74 . In contrast, the eccentric aperture  90  has an offset axis  98 , which is displaced from axis  96  to form the lip  82  and groove  84  of varying depth. In the illustrated embodiment, the lip  82  and groove  84  have a depth that varies from a maximum depth  100  to a minimal depth  102  at a point diametrically opposed to depth  100 . At the point of minimum depth  102 , the groove  84  is substantially flush with eccentric aperture  90 . Various other configurations can be provided in which the minimum depth does not vary down to the point at which the groove and aperture are flush with one another. As noted above, the illustrated configuration permits the threaded fastener  74  to be installed on the sleeve  70  and engaged on the external threads  88  of sleeve  72 . In an assembly and mounting process, the threaded fastener  74  can be placed over the lip  78  and centered on the sleeve  70 , because the eccentric aperture  90  is larger in dimension than the lip  78  of the sleeve  70  with the bearing assembly, shaft and tapered sleeve positioned loosely with respect to one another. The sleeve  70  is then drawn outwardly into engagement with the threaded fastener  74 . Once engaged with the sleeve  70 , the threaded fastener  74  is threaded onto the sleeve  72  to draw the concentric sleeves  70  and  72  into wedging engagement with one another until the sleeve  72  compresses or wedges onto the shaft  14 . 
     Interaction of various surfaces of the threaded fastener  74  and concentric sleeves  70  and  72  are best illustrated in  FIG. 6 . In the illustrated embodiment, as threaded fastener  74  is rotated during assembly of the system, abutment face  92  of the threaded fastener  74  contacts the distal face  80  of the sleeve  70  to draw the concentric sleeves  70  and  72  into tight engagement with one another, thereby wedgingly compressing the sleeve  72  about the shaft  14  (see, e.g.,  FIG. 2 ). In an alternative embodiment, the lip formed on the threaded fastener can be engaged on a corresponding surface of the respective sleeve. However, in the present embodiment, full engagement of the distal face  80  of the sleeve  70  and the abutment face  92  of the threaded fastener  74  is preferred to force tight engagement of the concentric sleeves  70  and  72  about the shaft  14 . 
     The compressive fit mechanism  24  also may be disassembled and dismounted from the shaft  14  via reverse rotation and separation of the threaded fastener  74  through the eccentric aperture  90 . In the detailed view of  FIG. 6 , the outer surface  104  of the varying depth lip  82  formed on the threaded fastener  74  engages an inner surface  106  of lip  78  of the sleeve  70 . Although the two surfaces do not engage fully over 360°, it has been found that excellent force distribution can be obtained to cause separation of the concentric sleeves  70  and  72  and release of the sleeve  72  from the shaft  14 . Again, the threaded fastener  74  is maintained centered by engagement on the external threads  88  of the sleeve  72 . Following the initial release of the concentric sleeves  70  and  72 , the system can be fully disassembled by disengaging the threaded fastener  74  from the sleeve  72 , by removing the concentric sleeves  70  and  72  from the shaft  14 , and by separating the concentric sleeves  70  and  72 . 
     As discussed above, the bearing assembly  12  may have a variety internal and external mounting mechanisms. The foregoing threaded fastener and compressive fit mechanisms  22  and  24  are exemplary mechanisms for internal mounting of the bearing assembly  12  about the shaft  14 . However, as mentioned above, the bearing assembly  12  also may have an external mounting mechanism to accommodate system expansion, contraction, and misalignment.  FIG. 7  illustrates an exemplary mountable outer casing  110 , which is disposed about the bearing assembly  12  illustrated in  FIG. 3 . In this exemplary embodiment, the mountable outer casing  110  has an internal cavity  112  with a retaining end  114  and an open end  116 , which allows insertion of the bearing assembly  12  into the mountable outer casing  110 . Once inserted into the internal cavity  112 , the bearing assembly  12  may be secured via retaining member  118  (e.g., a snap ring), which may be selectively disposed in one of a plurality of retainer grooves, such as grooves  120  and  122 . Each of these retainer grooves provides a different longitudinal mounting depth, which may be suitable for a particular bearing assembly or a desired amount of longitudinal float within the mountable outer casing  110 . Accordingly, the bearing assembly  12  is secured between the retaining end  114  and the retaining member  118 , such that the bearing assembly  12  may be longitudinally fixed or movable depending on the retaining groove selected for the retaining member  118 . In the illustrated configuration, opposite ends of the outer retaining sleeve  38  abut the retaining end  114  and the retaining member  118 , such that the bearing assembly  12  is longitudinally fixed within the mountable outer casing  110 . However, given the integral nature of the bearing assembly  12  and the clearance control and mount mechanism  16 , the retaining member  118  may be disposed in the groove  122  to provide a range of longitudinal float. This float can accommodate a wide variety of system expansion and contraction in the longitudinal direction. 
     The mountable outer casing  110  also may have an external geometry, such as a cylindrical or spherical geometry, which is insertable into a mount structure for the bearing assembly  12 . In the illustrated embodiment of  FIG. 7 , the mountable outer casing  110  has a spherical geometry, which is insertable into a spherical cavity to accommodate rotational movement, vibrations, misalignment, and other positional anomalies in the system.  FIGS. 8–10  illustrate an exemplary bearing system  200  having the bearing assembly  12  inserted into a mount structure  202  via the mountable outer casing  110 . The mount structure  202  may be a multi-piece or integral structure, such as the one-piece structure illustrated in  FIGS. 8–10 . The mount structure  202  also may have one or fastening mechanisms, such as fastener receptacles  204 , to couple the mount structure  202  to a desired structure. 
     As illustrated in  FIG. 8 , the mount structure  202  also has a partially spherical mount chamber  206  with opposite mounting slots  208 . The bearing assembly  12  is insertable into the spherical mount chamber  206  by aligning the mountable outer casing  110  with the opposite slots  208 . It should be noted that the foregoing alignment and insertion may be performed without all or part of the compressive fit mechanism  24  (e.g., the threaded fastener  74 ). If already assembled, then all or part of the compressive fit mechanism  24  (e.g., the threaded fastener  74 ) may be removed to facilitate insertion of the bearing assembly  12  into the spherical mount chamber  206 . 
     Once inserted into the spherical mount chamber  206 , the bearing assembly  12  may be rotated approximately 90 degrees to align a longitudinal axis  210  of the bearing assembly  12  with a longitudinal axis  212  of the mount structure  202 , as illustrated in  FIG. 9 . The rotation of the bearing assembly  12  also positions the mountable outer casing  110  in a blocked relationship within the spherical mount chamber  206 . If previously unassembled or removed, the compressive fit mechanism  24  (e.g., the threaded fastener  74 ) may be assembled with the bearing assembly  12 . It also should be noted that the protruding geometry of the compressive fit mechanism  24  (e.g., the threaded fastener  74 ) may further secure the bearing assembly  12  within the spherical mount chamber  206 . For example, the threaded fastener  74  may extend beyond the diameter of the spherical mount chamber  206 , thereby preventing realignment and removal of the mountable outer casing  110  through the opposite slots  208 . The bearing assembly  12  is removed by reversing the foregoing procedure, such that the mountable outer casing  110  is aligned and removed through the opposite slots  208 . 
     The bearing system  200  also has an integral lubrication system, which facilitates lubrication of the bearing assembly  12  at various stages of assembly and operation. As illustrated in  FIG. 10 , the mount structure  202  has a lubrication nipple  214  coupled to a lubrication passageway  216 , which extends into the spherical mount chamber  206 . At the inner surface of the spherical mount chamber  206 , the lubrication passageway  216  may have one or more lubrication grooves extending circumferentially around the spherical mount chamber  206 . The lubrication passageway  216  (and optional groove) is also alignable with a lubrication passageway  218 , which extends through the mountable outer casing  120  and into the internal cavity  112 . In the illustrated embodiment, the mountable outer casing  120  also has a circumferential outer groove  220  alignable with the lubrication passageway  216  to facilitate the distribution of a lubrication fluid between the spherical mount chamber  206  and the mountable outer casing  110  of the bearing assembly. At the inner surface of the internal cavity  112 , the lubrication passageway  218  is alignable with the lubrication receptacles  46  and  48 , which extend through the clearance control and support mechanism  16  to the tapered roller arrays  18  and  20 . The illustrated casing  120  also has a circumferential inner groove  222 , which ensures lubrication flow through the lubrication receptacles  46  and  48  regardless of the bearing assembly&#39;s longitudinal position within the mountable outer casing  110 . For example, the circumferential inner groove  222  can be fluidly coupled with the lubrication receptacles  46  and  48  as the bearing assembly  12  floats longitudinally between the retaining end  114  and the retaining member  118 . 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.