Patent Publication Number: US-2006006608-A1

Title: Sector shaft pressure seal

Description:
FIELD OF THE INVENTION  
      The present invention relates to a radial shaft seal, and more particularly to a composite radial shaft seal having a sealing member adapted to frictionally maintain non-rotational motion of the seal.  
     BACKGROUND OF THE INVENTION  
      Hydraulic systems often include a shaft and bore assembly adapted for relative rotational or axial displacement. Seals are implemented to contain fluid from one media type to another Typically, these hydraulic seals are annular shaped and are provided between the bore and shaft. An annular groove formed in the bore holds the seal. Typical seals are constructed of rubber or other flexible, oil resistant material. To seal higher pressures, back-up rings are used to prevent extrusion. One means of preventing extrusion has been to use composite seals. Composite seals include a soft rubber sealing portion and a harder structural base portion. The base portion functions to support the seal under high pressures and its inherent rigidity resists the aforementioned extrusion.  
     SUMMARY OF THE INVENTION  
      The present invention provides a hydraulic seal assembly that is adapted to frictionally engage an annular groove formed in a bore, thereby maintaining its rotational disposition. The seal assembly comprises an annular sealing member mechanically engaged with an annular support member. The sealing member includes a heel portion having a generally L-shaped cross-section and a sealing portion having a generally V-shaped cross-section. The heel portion and the outer lip are adapted to frictionally engage the annular groove to limit rotation of the seal assembly therein. The annular support member has a generally upside-down L-shaped cross-section and is mechanically interconnected with the heel portion of the sealing member. The support member is adapted to support the sealing member under axial and rotational loading conditions. The support member typically is constructed of a material that has a higher modulus than the sealing member to resist deformation.  
      Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is a cut-out perspective view of a seal assembly in accordance with the present invention;  
       FIG. 2  is an exploded cross-sectional view of the seal assembly of  FIG. 1 ;  
       FIG. 3  is a partial cross-sectional view of the seal assembly of  FIG. 1 ; and  
       FIG. 4  is a cross-sectional view of an alternative embodiment of a seal assembly in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the scope of the invention, its application, or its uses.  
      With reference to  FIGS. 1 and 2 , a seal assembly  10  in accordance with the present invention is described. The seal assembly  10  includes an annular sealing member  12  and an annular support member  14 .  
      The sealing member  12  is a one-piece member that includes a heel portion  16  and a static sealing portion  18 . According to a first embodiment, the heel portion  16  has a generally L-shaped cross-section that defines a first axially extending leg surface  20 , a second leg surface  22 , a table surface  24 , and a radially extending sole surface  56 . The first and second leg surfaces  20 ,  22  are substantially parallel and the table surface  24  extends generally perpendicular ( FIG. 2 ) or angular ( FIG. 4 ) therebetween.  
      The sealing portion  18  of the sealing member  12  is axially disposed relative to the heel portion  16  and has a generally V-shaped cross-section. The sealing portion  18  defines an inner lip  26 , an outer lip  28 , and an annular groove  30  disposed on an axial face of the sealing portion  18 . The annular groove  30  is adapted to enhance radial deformation of the sealing member  12  by allowing the sealing portion  18  to flex. The sealing portion  18  further defines a radially converging surface  32  extending from the inner lip  26  toward the heel portion  16 . In an exemplary embodiment, the sealing member  12  is constructed of a deformable, material such as an elastomer. Preferably, an oil resistant material such as nitrile rubber or hydrogenated nitrile rubber can be used. By way of example, it is envisioned that the sealing member  12  has a Shore A durometer hardness of approximately 60-90. It should be appreciated, however, that any flexible, oil resistant material capable of providing a hydraulic seal is intended to be within the scope of the present invention.  
      The support member  14  has a generally inverted L-shaped cross-section that defines a first outer engaging surface  34 , a second radially inward outer engaging surface  36 , a lower engaging surface  38  extending radially inward from the first outer engaging surface  34  toward the second outer engaging surface  36 , first and second radially extending support surfaces  40 ,  42 , and an inner diameter surface  60 . The first and second outer engaging surfaces  34 ,  36  are virtually parallel to one another and the lower engaging surface  38  extends generally perpendicular ( FIG. 2 ) or angular ( FIG. 4 ) therebetween. The first support surface  40  is adapted to support the radially converging surface  32  of the sealing member  12  under axial and/or radial loading. In an exemplary embodiment, the support member  14  is constructed of a material that has a higher modulus material (such as polyurethane) than sealing member  12 . By way of example, it is envisioned that the support member  14  has a Shore A durometer hardness of approximately 60-100. It should be appreciated, however, that any material stiffer than the sealing member  12  and capable of supporting the sealing member  12  under axial and/or radial loading is intended to be within the scope of the present invention.  
      With reference now to  FIGS. 2 and 3 , the support member  14  is mechanically engaged with the heel portion  16  and static sealing portion  18  of the sealing member  12 . The first leg surface  20  is radially engaged with the first outer engaging surface  34 . The second leg surface  22  is radially engaged with the second outer engaging surface  36 . A mechanical lock created by the above-described radial engagement limits relative rotational displacement of the sealing and support members  12 ,  14 . The table surface  24  is axially engaged with the lower engaging surface  38 . This engagement provides axial support to the sealing member  12  relative to the support member  14 .  
      With further reference to  FIG. 3 , the seal assembly  10  is installed in an annular groove  44  that is formed in a bore  46  that contains a shaft  48 . The annular groove  44  includes a top wall  50 , a side wall  52 , and a bottom wall  54 . The seal assembly  10  is disposed in the groove  44  such that the sole surface  56  of the heel portion  16  and the second support surface  42  of the support member  14  frictionally engage the bottom wall  54  of the bore  44 . Furthermore, the outer lip  28  engages with sidewall  52  and the inner lip  26  engages with the shaft  48 , respectively, thereby providing a fluid tight seal. Friction created by the engagement between the outer lip  28  and heel portion  16  of the sealing member  12  and the annular groove  44  substantially limits rotational displacement of the seal assembly  10 .  
      With reference now to  FIG. 4 , an alternative exemplary embodiment of the present invention is described. All aspects of the alternative embodiment of the seal assembly  10  are identical to that described above with the exception of the interface between the sealing and the support members  12 ,  14 .  
      The first and second leg surfaces  20 ,  22  remain parallel, as well as the first and second outer engaging surfaces  34 ,  36 . The table surface  24  and the lower engaging surface  38 , however, extend at angles relative to the leg surfaces  20 ,  22  and outer engaging surfaces  34 ,  36 , respectively. The table surface  24 , however, extends angularly radially upward and inward from the first leg surface  20  to the second leg surface  22 . The lower engaging surface  38  extends angularly radially upward and inward from the first outer engaging surface  34  to the second outer engaging surface  36 . Cooperative engagement of the table surface  24  and the lower engaging surface  38  limits radial separation of the sealing member  12  and the support member  14 . In an exemplary embodiment, the table surface  24  and the lower engaging surface  38  engage in a plane extending at approximately 45° from the first leg surface  20 . It should be appreciated, however, that any angle capable of limiting radial separation of the sealing and support members  12 ,  14  is intended to be within the scope of the present invention.  
      The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.