Abstract:
A bearing directed to a bushing positioned within a housing that is positively retained to prevent the bushing from moving axially with respect to the housing and that also prevents the bushing from rotating relative to the housing. The present embodiment accomplishes these goals by the use of a retention pin that positively retains the bushing within the housing.

Description:
FIELD OF THE INVENTION 
     This invention is directed generally to bearing assemblies, and more particularly bushing bearings. 
     BACKGROUND 
     Bearing assemblies often include various components including rolling elements that are retained within the assembly to reduce friction and wear between moving parts or surfaces. In some bearing assembly applications, a bushing is used in place of rolling elements to eliminate the necessity for the rolling elements, grease, and retainer. The bushing usually exhibits self-lubricating and shock absorbing properties allowing the bearing to run smoothly and quietly. Often the bushing is made up of a polymer such as Polytetrafluoroethylene (PTFE). 
     The bushing is often press-fitted inside the bearing assemblies housing, and the bushing is retained by the pressure of the press-fit. In high pressure applications, or in applications where high temperatures are experienced, the bushing will creep during its useful life and the press-fit pressure may be lost. This may result in the bushing rotating within the bearing housing. Other conditions, may also cause the bushing to undesirably rotate within the housing leading to reduced bearing or bushing life. 
     To prevent any relative movement between the bushing and the housing, some have attempted to use an adhesive to positively lock the bushing within the housing. However, over time and under high temperature, the adhesive has been found to degrade and the bushing may either undesirably come out of the housing, or rotate within the housing. Such methods and results are unacceptable and consequently lead to reduced bearing life and machine downtime. 
     Another method for retaining the bushing within the housing has been to provide a circumferential groove within the housing and to provide a corresponding bumper on the outer diameter of the bushing. Sometimes this method has been used in connection with an adhesive. In this manner, the polymer bushing is snap fit into the circumferential groove within the housing and retained within the housing. This method may prevent the bushing from moving axially with respect to the housing. However, it does not prevent the bushing from rotating, or spinning within the housing when the adhesive degrades. 
     Thus, there is a need in the art to provide a bushing that will remain positively retained within the housing. 
     SUMMARY 
     The present embodiment is specifically directed to a bushing positioned within a housing that is positively retained to prevent the bushing from moving axially with respect to the housing and that also prevents the bushing from rotating relative to the housing. The present embodiment utilizes a retention pin that positively retains the bushing within the housing. 
     In an aspect of the present embodiment, a bushing is mechanically locked within a housing to reduce movement of the bushing in axial and circumferential directions relative to the housing. In an exemplary embodiment, a bearing assembly includes at least one retention pin that mechanically locks the bushing within the bearing housing. 
     In another aspect of the present invention, a locking pin retains an inner ring positioned within an outer ring. The locking pin retains the inner ring from rotating in relation to the outer ring in an axial and circumferential direction. In the exemplary embodiment, the inner ring includes a polymer bushing, and the outer ring includes a housing. 
     The present embodiments can be utilized in bearings that may be exposed to harsh operating conditions, including subjection to high temperatures and pressure. They provide the ability to retain a bushing within a housing. Consequently, movement of the bushing is reduced in an axial and circumferential direction relative to the housing. 
     The foregoing and other objects, features and advantages of the bearing or bearing assembly will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view of an exemplary bushing bearing showing a portion of the retention pin and sleeve; 
     FIG. 2 is another view of the bushing bearing and retention pin of FIG. 1, without sleeve; 
     FIG. 3 is a sectional view of the bushing bearing of FIG. 1 that further illustrates the retention pin and retention pin aperture; and 
     FIG. 4 is a sectional, partial view of the bushing bearing of FIG. 3 further illustrating the retention pin and retention pin aperture. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present embodiment is illustrated in exemplary embodiments that disclose a system and device for reducing movement of a bushing in an axial and circumferential direction. More specifically, the exemplary embodiments have been implemented on a polymer bushing bearing. It should be understood that the present embodiment may be utilized on other bearing types and other bushing materials where a reduced movement of the bushing is desired. Therefore details regarding the bearing are provided as an example, and are not necessary to the invention unless otherwise specified. 
     FIG. 1 illustrates an exemplary polymer bushing bearing  10  showing a portion of retention pin  14  and sleeve  18 . The sleeve  18 , shown outside of the bearing  10  for purposes of illustration only, is preferably positioned within the bearing  10  along arrows  30  and  32 , such that the sleeve surface  34  is in contact with the polymer bushing  22 . The polymer bushing  22  is positioned and retained within the bearing housing  26 . The polymer bushing  22  is retained within the bearing housing  26  by retention pin  14 . Note that the bearing housing  26  may be configured to accommodate any desired bearing application, and thus the bearing housing  26  should not be limited to the cylindrical configuration such as shown for clarity in FIG.  1 . For example, some bearing housing configurations may be developed for fastening the bearing  10  to another device or object, accepting different types of loads, sealing out contaminants, and so forth. 
     The sleeve  18  is positioned within the bearing  10  such that the sleeve  18  can rotate in a circumferential direction illustrated by arrows  40  around the central bearing axis  44 . In the exemplary embodiment, the sleeve  18  is a metal alloy, although other materials known in the art may be utilized. A shaft (not shown) may be positioned within and fastened to the sleeve  18  as is known in the art, such as by tightening screws, bolts, clamps, pins, welding, and so on. In an alternate embodiment, the sleeve  18  and shaft are integral to each other to eliminate the need for tightening screws or the other types of fasteners. Note that the sleeve  18  may be configured to accommodate any desired bearing application, and thus the sleeve  18  should not be limited to the cylindrical configuration such as shown for clarity in FIG. 1 
     In the exemplary embodiment, the bearing housing  26  is a metal alloy, although other materials known in the art may be utilized. The bearing housing  26  can be fastened or mounted to a structure or device (not shown for clarity) such that when the sleeve  18  is rotating, the bearing housing  26  and preferably the bushing  22  is prevented from rotating in the direction of the sleeve  18 . To fasten the bearing housing  26  to a particular structure or device, methods known in the art such as tightening screws, bolts, clamps, pins, welding, and so on for securing the bearing housing  26  to the device may be used. In an alternate embodiment, the bearing housing  26  can rotate rather than sleeve  18  that has been fastened or mounted to a structure or device, depending on the particular bearing application. 
     Preferably, the retention pin  14  mechanically locks the bushing  22  to the bearing housing  26 . In the exemplary embodiment, the retention pin  14  and the bushing  22  are constructed of Polytetrafluoroethylene (PTFE). According to this embodiment, the retention pin  14  is made from a material similar to the bushing  22  (e.g., PTFE), such that there is little or no additional distresses on the bushing  22 . It should be understood, however, that a stronger retention pin  14  material may be used, for more demanding bearing applications. 
     FIG. 2 is another view of the bushing bearing  10  and a portion of retention pin  14  of FIG. 1, however the sleeve  18  has been removed in FIG. 2 for purposes of illustration. As described above, the bushing  22  is polymer material such as PTFE, but other materials suitable for these types of bearing applications may be utilized. To retain the bushing  22  within the bearing housing  26 , a retainer pin  14  may be used. Other known mechanisms for fastening or retaining the bushing  22  within the bearing housing  26  such as grooves and adhesive may be used with the retention pin  14 . 
     FIG. 3 is a sectional view of the bushing bearing  10  of FIG. 1 that further illustrates the retention pin  14  and retention pin aperture  24 . Preferably, the size and configuration of the retainer pin  14  complements the corresponding retention pin aperture  24 . The retainer pin  14  preferably includes a first end  32  and a second end  36 . In the exemplary embodiment, the first end  32  is similar in size and configuration as the second end  36 . Although it should be understood that the first end  32  and the second end  36  can be different in size and configuration, depending on the particular bearing application. Preferably, the retainer pin  14  and the corresponding aperture  24  are made with a degree of precision such that there are low tolerances for a close fit. Adhesives may be utilized to secure the retainer pin  14  in aperture  24 . Moreover, the first end  32  should not project out of the bushing  22 , so that a sleeve (e.g.,  18  in FIG. 1) remains in close contact with the bushing  22  and not necessarily the first end  32  of the retention pin  14 . 
     FIG. 4 is a sectional, partial view of the bushing bearing  10  of FIG. 3 further illustrating the retention pin  14  and retention pin aperture  24 . FIG. 4 illustrates section A—A of FIG. 3 to show the bearing  10 , retention pin  14 , and retention pin aperture  24  from a different viewpoint. 
     Referring to FIGS. 3 and 4, the retainer pin  14  can prevent the bushing  22  from rotating in either one of the two circumferential directions  40  and in either one of the two the axial directions along central bearing axis (e.g.,  44  in FIGS.  1  and  4 ), relative to the bushing  22 . This is especially useful to prevent the bushing  22  from spinning inside of the bearing housing  26  when the sleeve is rotating and the bearing  10  is under high pressure or high temperature conditions. If desired, the retainer pin  14  can be used with other retention methods as are known in the art such as adhesive, grooves, or adhesive and grooves. 
     According to the exemplary embodiment, the sleeve (e.g.,  18  in FIG. 1) is allowed to rotate relative to the bushing  22  in either one of the two circumferential directions. Therefore, the bushing  22  can operate as an anti-friction liner between the sleeve and bearing housing  26 . Preferably, the bushing  22  remains locked in a position relative to the bearing housing  26  to prevent spinning along with the sleeve. To lock the bushing  22  in the axial and circumferential directions, the retention pin  14  is utilized. It is also possible to include more than one retention pin to retain the bushing  22  within the bearing housing  26 , and may be placed anywhere inside of the bushing  22 . 
     The retention pin  14  is fabricated from a material such as polymer and is sized and configured to the retention pin aperture  24 . The retention pin  14  can be made of other materials such as metals and alloys, depending on the particular application. Stronger materials may be used for more demanding applications. Preferably, the retention pin  14  is made from a material similar to the bushing  22  to reduce any distresses that may arise on the bushing  22 . 
     According to the exemplary embodiment, the retention pin  14  is preferably inserted into the retention pin aperture  24  after the bushing  22  is positioned within the bearing housing  26 . In this embodiment, the retention pin aperture  24  includes a bushing aperture  62  and a housing aperture  66 . When the bushing  22  is properly positioned within the bearing housing  26 , the bushing aperture  62  and housing aperture  66  preferably align to form the retention pin aperture  24 . A phantom line shows where the bushing aperture  62  and housing aperture  66  align to form the retention pin aperture  24 , and where the bushing  22  and bearing housing  26  meet. The retention pin  14  may be positioned within the retention pin aperture  24 . Moreover, adhesives can be utilized to reduce movement of the retention pin  14  within the retention aperture  24 . 
     Limits and fits can be used to specify dimensions for the retention pin aperture  24  and retention pin  14 . Two exemplary standards on limits and fits are described by the American National Standards Institute and are given by ANSI B4.1, B4.2, and B4.3. As is known in the art, these standards are divided into classes depending on the desired fit between the aperture and pin. Other methods known in the art can be used to specify dimensions. 
     In another embodiment, the retention pin  14  can be integral with the bushing  22 . Therefore, upon positioning the bushing  22  within the bearing housing  26 , the retention pin  14  can also be positioned with the retention pin aperture or housing aperture. 
     In yet another embodiment, the retention pin  14  can be integral with the bearing housing  26 . When the bushing  22  is positioned within the bearing housing  26 , the retention pin  14  can be positioned within the retention pin aperture or bushing aperture. 
     It should be understood that the processes, methods and systems described herein are not related or limited to any particular type bearing, unless indicated otherwise. Various types of general purpose or specialized bearings may be used in accordance with the teachings described herein. 
     In view of the wide variety of embodiments to which the principles of the present embodiments can be applied, it should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the present invention. For example, more or fewer elements may be used in the drawings. 
     The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.