Abstract:
A locking joint seal includes a ring-shaped body made from poly tetra fluoroethylene and having a first end and a second end. The first and second ends each include mutually engageable first and second locking features. The first locking feature including a first axially extending portion overlapping a second axially extending portion of the second locking feature in an assembled condition.

Description:
FIELD 
     The present disclosure relates to seals and more particularly to a locking joint seal. 
     BACKGROUND AND SUMMARY 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     A type of a split rotating seal, widely known as a scarf cut plastic seal, is used in many industries and is manufactured by a large number of companies worldwide. This type of seal is used in modern automatic transmissions to seal shafts and clutch components against the passage of hydraulic fluid, usually transmission fluid. An exemplary scarf cut seal is disclosed in U.S. Pat. No. 7,010,844. 
     In many cases, a scarf cut plastic seal is made from PTFE compound, short slender fibers of glass, graphite or Kevlar, and a number of additives, the amalgam being a homogeneous mixture of PTFE compound, the fibers and additives. A purpose of the fibers is to reinforce the PTFE compound in order to improve its structural properties or to produce a seal whose functional characteristics are particularly suited to an application of the seal or to the environment in which the seal is intended to function. The additives have a similar purpose. 
     This type of seal typically has a rectangular cross section and a beveled split or scarf cut having an angle in the range of 7-45 degrees when projected on the longitudinal axis of the seal. This type of seal can be installed in an outer groove formed in the outer surface or journal of a rotating or stationary shaft. Alternatively, the seal can be installed in an internal groove formed in a bore of a rotating or stationary housing. 
     Scarf cut seals tend to loose their cylindrical form due to radial compression, which results in plastic deformation. They become dislocated in the retaining groove due to clearance between the surfaces of the seal and the groove, and they are susceptible to deformation. These factors cause unintended interference between the installed seal and shaft as the shaft is inserted within a bore. The seal is often cut by the shaft during shaft installation, commonly referred to as a “cut seal” condition. Or the seal is unintentionally forced from its groove by the shaft as the shaft slides in the bore past the installed seal. 
     Accordingly, it is desirable to provide a jointed seal with improved retention characteristics as compared to scarf cut seals. According to the present disclosure, a locking joint seal includes a ring-shaped body made from PTFE, rubber, thermal plastic material, or other known seal materials, and having a first end and a second end. The first and second ends each include mutually engageable first and second locking features. The first locking feature including a first axially extending portion overlapping a second axially extending portion of the second locking feature in an assembled condition. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a plan view of a locking joint seal according to the principles of the present disclosure; 
         FIG. 2  is a side plan view of a locking joint seal illustrating the locking joint according to the principles of the present disclosure; 
         FIG. 3  is a side plan view of a locking joint seal having an alternative locking joint design; 
         FIG. 4  is a side plan view of still another locking joint seal having still another locking joint design; and 
         FIG. 5  is a side plan view of a locking joint seal having still another locking joint design. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     With reference to  FIGS. 1 and 2 , a locking joint seal  10  according to the principles of the present disclosure will now be described. The locking joint seal  10  includes a ring-shaped body  12  including an inner diameter face  14 , an outer diameter face  16  and first and second side faces  18 ,  20  axially facing in opposite directions. The ring-shaped body  12  includes a longitudinal axis A. 
     The ring-shaped body  12  includes a first end  22  and a second end  24 . The first end  22  includes a first locking feature  26  and the second end  24  includes a second locking feature  28 . The first and second locking features can be in the form of first and second hooks. The first and second locking features  26 ,  28  can each include a hook base surface  30  extending axially from the first side face  18 . A first hook inner face  32  is adjacent to the hook base surface  30  and extends generally circumferentially therefrom. An axially extending portion  34  extends from the hook inner face in a direction so as to overlap the hook base surface  30  in an axial direction. A hook side face  36  is adjacent to the axially extending portion  34  and a hook end face  38  extends axially from and adjacent to the hook side face  36  to the second side face  20  of the ring-shaped body  12 . 
     It should be understood that the second locking feature  28  is similarly constructed to the first locking feature  26  as just described. In the assembled condition, the first locking feature  26  engages the second locking feature such that the first hook base surface  30  is disposed adjacent to the hook end face  38  of the second locking feature  28 . The hook inner face  32  of the first locking feature  26  is disposed adjacent to the hook side face  36  of the second locking feature  28 . The axially extending portions  34  of the first and second locking features are disposed adjacent to one another, the hook side face  36  of the first locking feature  26  is disposed adjacent to the hook inner surface  32  of the second locking feature  28  and the hook end face  38  of the first locking feature  26  is disposed adjacent to the hook base surface  30  of the second locking feature  28 . 
     It should be understood that the hook base surface  30 , the first hook inner surface  32 , the axially extending portion  34 , the hook side face  36  and hook end face  38  can each define planar surfaces as shown, or alternatively, the surfaces can be curved so long as they allow locking engagement between the first and second ends  22 ,  24  of the ring-shaped body  12 . 
     With reference to  FIGS. 3-5 , it is illustrated that the surfaces  30 - 38  can take on many different angular orientations without departing from the spirit and scope of the present disclosure. In particular, as shown in  FIG. 3 , the hook base surface  130  is at an acute angle relative to the second side face  18  and the hook inner face  132  can be angled relative to the plane of the side face  18 . In addition, the axially extending portion  134  can also be angled relative to the longitudinal axis. Furthermore, the hook side face  136  can also be angled relative to the longitudinal axis and the hook end face  138  can be angled at an obtuse angle relative to the side face  20 .  FIGS. 4 and 5  illustrate further embodiments of the various geometries that can be utilized for the first and second locking features. In particular,  FIG. 5  illustrates that the angles provided between each of the surfaces of the locking features can be varied depending upon different applications.  FIG. 4  shows a hook base surface that includes a surface  230   a  that is perpendicular to the side face  18  and can include an angled surface  230   b  extending from the surface  230   a . In addition, the end face can include a surface  238   a  that is perpendicular to the side face  20  and can include an angled surface  238   b  extending from the surface  238   a.    
     The method of manufacturing the locking joint seal  10  will now be described. The method of manufacturing includes providing a continuous ring-shaped body which can be formed from PTFE, rubber, thermal plastic material, or other known seal materials, that can include additional fibers and additives as desired for particular applications. The ring-shaped body can be provided with an inner diameter surface, an outer diameter surface and first and second side surfaces. Each of the inner, outer and side surfaces can be generally flat in cross section, or can be provided with a curvature or other undulations. The ring-shaped body is then cut with a blade or other cutting device such as a laser so as to provide the jagged-shaped interface of the first and second ends as described in detail above. In particular, a blade having the jagged configuration of the interface between the first and second ends can be inserted from the outer diameter surface toward the inner diameter surface in order to create the first and second ends  22 ,  24  which matingly engage with one another as described above. 
     Comparative leak testing has been performed utilizing the locking joint seal  10  according to the principles of the present disclosure and comparing the results to scarf cut seals and continuous seals. In these comparative tests, the locking joint seals allowed 53% leakage at 76° F. and 40% less leakage at 300° F. than the scarf cut seal, according to the principles of the present disclosure. The continuous uncut seal allowed 65 percent less leakage of oil at 76° F. and 60 percent less of oil leakage at 300° F. than the scarf cut seal, but does not provide for the ease of assembly that is obtained with the locking joint seal or the scarf cut seal. The continuous uncut seal also is also more susceptible to damage during the assembly process which is not a concern with the locking joint seal of the present disclosure. Accordingly, the locking joint seal of the present disclosure provides all of the ease of assembly of the scarf cut seal with improved sealing characteristics. While the locking joint seal allowed slightly more oil leakage than the continuous uncut seal, the continuous uncut seal is subject to damage due to cracking when the seal is stretched during assembled.