Patent Publication Number: US-2005121858-A1

Title: Support of PTFE sealing element

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This descriptive report refers to a patent of invention for sealing element pertaining to the field of sealing devices for automotive use, mainly, which was improved to provide performance superior to the similar conventional product, especially for applications involving eccentric axles or eccentricities originated from the use.  
      2. Description of the Related Art  
      There are available sealing devices of polytetrafluoroethylene, PTFE, used to compose radial sealing devices of axles, stems, or similar parts in automotive applications, mainly.  
      Concerning the good performance of the PTFE sealing element, it is relatively plastic, which implies in a slow return to its original form after having suffered radial deformation during the use. This is observed mainly when the PTFE sealing element is used in the sealing of eccentric axles or of axles presenting a certain eccentricity resulted from gaps in the project and/or gaps originated along the useful life of the product, or due to other reasons. This situation is not desired, since it allows a defective sealing.  
     SUMMARY OF THE INVENTION  
      Thus, the invention object of this patent is intended to provide a PTFE sealing element with the solution for the problem above.  
      Another objective is to provide a sealing element that, in spite of resolving the problem above, is of easy manufacture.  
      Another objective is to provide a sealing element with convenient cost.  
      Therefore, in light of the problem listed above and in order to overcome it, observing the objectives listed and any others, we developed the improvement of sealing element object of this patent of invention, which basically consists in the association of the PTFE sealing element to an elastic element, which it on its turn is arranged to hasten the return of the sealing element against the surface sealed, when said sealing element is radially deformed during the use.  
      This manner of construction of the sealing element resolves the problem mentioned above, since it inhibits the plastic property of the PTFE, providing the element with elasticity sufficient to maintain, or return, it rapidly to the position of use, avoiding defects during the use.  
      On the other hand, the sealing element object hereof does not carry technical complications to the productive process, nor high manufacturing costs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The drawings attached hereto refer to the improvement of the support of PTFE sealing element object hereof, where:  
       FIG. 1  demonstrates a sealing element in cut, composed with the sealing element according to the invention; and  
       FIG. 2  demonstrates another possibility for the sealing element invented. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Pursuant to the figures aforementioned, the sealing element  1 , object hereof, is made of polytetrafluoroethylene, PTFE, consisting in a circular-crown-shaped body, with: an internal section with sealing surface  2  provided with hydrodynamic sealing  3 , fold intermediary section  4 , and peripheral settlement section  5 .  
      The PTFE sealing element  1 , constructed as mentioned above, is used to compose sealing devices  10  destined to the radial sealing of axles, stems, or similar parts  20  of automotive mechanisms or components, mainly, or others; these sealing devices  10  basically include: main radial sealing, formed by the PTFE sealing element  1 , which causes the sealing against the axle, stem, or similar part  20 ; rubber auxiliary sealing ring  11 , which protects the main sealing against dirt; and a ring frame  12 , which incorporates the main  1  and auxiliary  11  sealing.  
      The improvement object hereto consists in the association of the polytetrafluoroethylene sealing element  1 , PTFE, with circular-crown shape and provided with hydrodynamic sealing  3  to an elastic element  30  disposed to be tensioned whenever the PTFE sealing element  1  suffers radial deformations during use, and to be extended and to accelerate the return of the PTFE sealing element to the original form against the surface sealed  20 , when the deformation strengths cease.  
      In one possibility of execution ( FIG. 1 ), said elastic element  30  is basically composed of a spring steel open ring  31  incorporated to the external surface  4  of the PTFE sealing element  1  opposed to the sealing surface  2 , provided with hydrodynamic sealing  3 , which provides sealing against the surface of the axle, stem or other parts  20 .  
      Thus, when the sealing surface  2  of the PTFE sealing element  1  is deformed radially outwards due to strengths resulted from the eccentricity of the axle, stem or other part  20 , the spring steel open ring  31  is correspondently tensioned. Upon the end of the strengths of radial deformation on the sealing surface  2  of the PTFE sealing element  1 , spring steel open ring  31  distends and returns rapidly the PTFE sealing element  1  to its original form in conjunction with the axle or other part  20 , thus avoiding the memory of the PTFE from delaying the return and allowing a loss of sealing.  
      Within the basic construction aforementioned, the PTFE sealing element object hereof may present modifications related to dimensions, constructive details, and/or functional configuration without affecting the scope of the protection requested.  
      Considering the aforementioned, instead of the elastic element  30  being constructed by an open ring  31 , as of the version described above, said elastic element  30  may consist ( FIG. 2 ) of a spring steel ring piece  32 - 33  with profile substantially equal to that of the PTFE sealing element  1 , disposed in the external surface thereof and basically composed of: axial tubular section  32  disposed adjacently to the external surface  4  of the PTFE sealing element  1  in opposition to the sealing surface itself  2 ; and by radial flange  33  turned outwards in relation to the axial tubular section  32  and adjacent to the region of the external surface  4  of the peripheral settlement section  5  of the PTFE sealing element  1 ; said axial tubular section  32  is provided with longitudinal cuts  34 , extended from its free edge to the vertex region in relation to flange  33 .