Abstract:
A bearing retainer having an inner portion, an outer portion spaced apart from said inner portion, and an intermediate portion connecting the inner portion and the outer portion, such that the inner portion and the outer portion are radially spaced apart and define a space therebetween, and a contact surface on at least one of the inner portion and the outer portion for engaging a component of a bearing assembly disposed in the space.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/833,865, filed Aug. 3, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The technology described herein relates generally to gas turbine engine components and more specifically to bearing retainers. 
         [0003]    Gas turbine engines typically include a compressor, a combustor, and at least one turbine. The compressor may compress air, which may be mixed with fuel and channeled to the combustor. The mixture may then be ignited for generating hot combustion gases, and the combustion gases may be channeled to the turbine. The turbine may extract energy from the combustion gases for powering the compressor, as well as producing useful work to propel an aircraft in flight, such as by driving a fan or propeller, or to power a load, such as an electrical generator. 
         [0004]    Rotating turbomachinery, such as that found in gas turbine engines, frequently contains one or more bearing assemblies to support rotating components within stationary housings or between or within other rotating apparatus. Such bearing assemblies typically feature one or more bearing retainers to secure the bearing in place relative to other structures. Bearing retainers may be removable to permit initial assembly and/or repair of elements of the bearing assembly. 
         [0005]    Removable bearing retainers often take the form of a nut or collar threadably engaged externally or internally on the end of a shaft or housing. When the shaft or housing is subjected to significant cyclic loads or other radial motion under certain operating conditions, large deflections or distortion of the shaft or housing can occur which diminishes the contact between contacting surfaces of the bearing retainer and the shaft or housing. This diminished contact can lead to the bearing retainer “jumping threads” or otherwise moving axially relative to the shaft or housing and allowing the bearing to move from its installed position due to the loss of positive retention. 
         [0006]    Accordingly, there remains a need for a bearing retainer which is removable yet provides for enhanced contact under high deflection or distortion operating conditions. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0007]    A bearing retainer having an inner portion, an outer portion spaced apart from said inner portion, and an intermediate portion connecting the inner portion and the outer portion, such that the inner portion and the outer portion are radially spaced apart and define a space therebetween, and a contact surface on at least one of the inner portion and the outer portion for engaging a component of a bearing assembly disposed in the space. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional schematic view of an exemplary gas turbine engine. 
           [0009]      FIG. 2  is a partial cut-away cross-sectional view of an exemplary bearing assembly that may be used with a gas turbine engine, such as the gas turbine engine shown in  FIG. 1 . 
           [0010]      FIG. 3  is an enlarged partial view of the bearing retainer of  FIG. 2 . 
           [0011]      FIG. 4  is a view similar to  FIG. 2  of another embodiment of an exemplary bearing assembly. 
           [0012]      FIG. 5  is a view similar to  FIG. 2  of another embodiment of an exemplary bearing assembly. 
           [0013]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 2 . 
           [0014]      FIG. 7  is a cross-sectional view similar to  FIG. 6  taken along line  7 - 7  of  FIG. 2 . 
           [0015]      FIG. 8  is a partial perspective view of the exemplary bearing retainer of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 1  is a schematic illustration of an exemplary gas turbine engine  10  including a fan assembly  12 , a booster  14 , a high pressure compressor  16 , and a combustor  18 . The engine  10  also includes a high pressure turbine  20 , and a low pressure turbine  22 . The fan assembly  12  includes an array of fan blades  24  extending radially outward from a rotor disk  26 . The engine  10  has an intake side  28  and an exhaust side  30 . The engine  10  may be any gas turbine engine. For example, the engine  10  may be, but is not limited to being, a GE90 gas turbine engine available from General Electric Company, Cincinnati, Ohio. The fan assembly  12 , booster  14 , and turbine  22  may be coupled by a first rotor shaft  32 , and the compressor  16  and turbine  20  may be coupled by a second rotor shaft  34 . 
         [0017]    In operation, air flows through the fan assembly  12  and compressed air is supplied to the high pressure compressor  16  through the booster  14 . The highly compressed air is delivered to the combustor  18 , where it is mixed with a fuel and ignited to generate combustion gases. The combustion gases are channeled from the combustor  18  to drive the turbines  20  and  22 . The turbine  22  drives the fan assembly  12  and booster  14  by way of shaft  32 . The turbine  20  drives the compressor  16  by way of shaft  34 . 
         [0018]    As shown in  FIG. 2 , the engine  10  includes a bearing assembly  40 . Bearing assembly  40  includes a bearing  42 , a bearing retainer  44 , and a positive retention element  50 . Bearing retainer  44  includes an inner portion  46 , an outer portion  48 , and an intermediate portion  47  which connects the inner portion  46  and outer portion  48 . In the embodiment shown, the bearing retainer  44  is formed as an annular spanner nut with the inner and outer portions being laterally (in this instance radially) spaced apart and with a threaded contact surface  52  formed on the inner portion  46 . 
         [0019]    Bearing assembly  40  also includes a shaft extension  70  and a bearing housing  72 , as well as retainers  74  which may be formed as spanner nuts and secondary retention devices  76 . Contact surface  52  engages a component of the bearing assembly  40 , such as bearing housing  72 , to secure the bearing retainer  44  and thereby secure the bearing  42  within the housing  72 . Contact surface is configured so that such engagement is releasable, such that the contact surface and the bearing retainer are removably secured to the component, in this case the housing  72 . Removable securement allows for assembly of the components as well as disassembly for repair or replacement of components. 
         [0020]    As shown in  FIG. 2 , the inner and outer portions are radially spaced apart via the intermediate portion and define a space therebetween to capture between them (i.e., in the space they define therebetween) the element they are secured to so they follow such element through the range of motion, even during distortion, without disengaging from contact with the element. Depending upon the relative dimensions of the inner, outer, and intermediate portions, and their respective shapes, the bearing retainer  44  may have a c-shaped, j-shaped, “scorpion-shaped” (i.e., resembling a scorpion in profile with the tail extending rearward, upwardly, and then forward over the rear portion of the body), or other desired cross-section. 
         [0021]    The outer portion of the bearing retainer may be formed as a complete annular structure, such as depicted in the accompanying drawing figures. Alternatively, the outer portion may be formed as one or more annular segments. 
         [0022]    The retainer maintains the thread engagement of the inner portion  46  and the threaded contact surface  52  because when the bearing housing, for example, tries to ovalize and pull away radially from the retainer, the outer portion  48  of the retainer is there to engage the housing and thus pull the retainer along with it, thereby keeping the threads engaged. The smaller the gap and the more overlap between the tail of the outer portion  48  and the housing the more certain it is the parts will follow each other during deformation. 
         [0023]      FIG. 3  is an enlarged partial view of the bearing retainer of  FIG. 2 , which shows in greater detail the spatial relationship of the retainer to the housing. The amount of thread disengagement before the retainer fully moves with the bearing is controlled by the radial gap  60  between the outer portion  48  of the retainer  44  and the housing extension  54  and the stiffness of the retainer  44 . The smaller the gap and the more overlap between the tail of the outer portion  48  and the housing extension  54  the more certain it is the parts will follow each other during deformation. Therefore, the gap  60  is minimized but designed so as not to close during all anticipated normal assembly and operating conditions. 
         [0024]    An axial gap  62  is also defined between the intermediate portion  47  and the housing extension  54 . Like the radial gap  60 , axial gap  62  is minimized but designed so that the intermediate portion  47  and housing extension  54  will not make contact before the bearing contacting surface  45  makes contact with the bearing  42 . This relationship ensures that positive axial retention of the bearing  42  is provided by the retainer  44 . The bearing retainer  44  is therefore sized and adapted to contact and secure the mating element, such as bearing  42 , with the contact face  45  before the connecting portion  47  contacts the housing extension  54 . 
         [0025]    Bearing retainer  44  may be formed using any suitable manufacturing method. For example, bearing retainer  44  may be unitarily formed from a single piece of material, as shown in  FIG. 2 , or may be formed from two or more, i.e., multiple, individual elements which are joined together via any method suitable for the material or materials to be joined. By way of example, bearing retainer  44  may be unitarily formed from a single forging and machined as necessary to impart the desired geometry and surface finish. As another example, bearing retainer  44  may be formed of two or more separate pieces of material which are bonded to one another, such as brazing, soldering, or welding metallic elements together. 
         [0026]      FIG. 4  illustrates an alternative construction of the bearing retainer  44 . As shown in  FIG. 4 , the bearing retainer  44  is formed as a two-piece construction with the inner portion  46  and outer portion  48  each including a segment of the intermediate portion  47 , each of the mating surfaces of the intermediate portion  47  being welded together via a welded seam  49  to form an integral bearing retainer assembly. 
         [0027]      FIG. 5  illustrates another alternative construction of the bearing retainer  44 . As shown in  FIG. 5 , the bearing retainer  44  is formed as a two-piece construction with the inner portion  46  and outer portion  48  each including a segment of the intermediate portion  47 , each of the mating surfaces of the intermediate portion  47  being brazed together via a brazed seam  49  to form an integral bearing retainer assembly. 
         [0028]    In  FIGS. 2 ,  4 , and  5 , a positive retention feature  50  is included to prevent the bearing retainer  44  from rotating during vibrations and other forces encountered during gas turbine engine operation. This in turn prevents the bearing retainer from loosening due to rotating and following the threads on the contacting surface away from the fully-seated position. Any type of positive retention feature may be utilized, such as a bolt, screw, cotter pin, key and keyway, lockwire, or polymeric anti-rotation compound such as may be commercially available. In the exemplary embodiment shown, positive retention feature  50  takes the form of a bolt with a complementary nut. Apertures may be provided in the bearing retainer  44  as needed for installation of the positive retention feature, such as the apertures  51  shown in  FIGS. 6 and 8 . Depending upon the type of positive retention feature required for the particular installation, the positive retention feature may comprise a single device or a plurality of devices, and accordingly may require a single aperture, slot, or other anchoring mechanism or a plurality of such anchoring mechanisms to be provided in the bearing retainer  44 . 
         [0029]      FIGS. 6 and 7  are cross-sectional views taken along lines  6 - 6  and  7 - 7 , respectively, of  FIG. 2 .  FIGS. 6 and 7  highlight details of the construction of the bearing retainer  44 . The bearing retainer  44  in the exemplary embodiment shown includes a plurality of radially inwardly facing alternating teeth  41  and slots  43  which may be used as a tooling engagement feature to thread the bearing retainer  44  onto the bearing housing extension  54  and tighten it securely using a spanner wrench or other appropriate assembly tooling. However, depending upon the assembly and installation method to be utilized, any type of tooling engagement feature may be provided in either single or multiple form. 
         [0030]    The bearing retainers described herein may be made of any material known in the art. Typical materials may be AMS 5643 stainless steel or any other steel alloy such as AMS 6414, nickel steels such as INCO 718, or titanium alloys. The choice of the material depends upon thermal, load, assembly, and operating environment and mating material, but is not limited to any particular material or class of materials. 
         [0031]    Bearing retainers of the type described herein may be useful in other installations besides gas turbine engines. For example, such retainers may be utilized in the automotive field or any other field where it is desired to retain a bearing in position during operation. The technology described herein may be applicable to any rotating machinery application where high load events may be of concern. Although initially envisioned and developed for rotating machinery, there may be potential for use on static machinery as well. 
         [0032]    While this application has described various specific exemplary embodiments, those skilled in the art will recognize that those exemplary embodiments can be practiced with modification within the spirit and scope of the claims.