Patent Publication Number: US-2005127616-A1

Title: Gasket between opposing sealing surfaces

Description:
TECHNICAL FIELD  
      The invention pertains to a gasket to be arranged between opposing sealing surfaces, particularly a flange gasket for a housing flange arranged on a housing and a correspondingly designed mounting plate.  
     BACKGROUND OF THE INVENTION  
      When mounting a housing that is provided with a flange and contains, for example, sensible components, a flange gasket of this type is required in order to ensure a reliable seal against an external industrial atmosphere. It is widely known to secure housings that can be assembled and are provided with a flange from environmental influences by means of a gasket arranged between the flanges. However, this does not ensure that the screw connections for holding the flanges together are also sealed relative to the environment in the region of the through-openings between the screw, the gasket and the flange.  
      DE 37 20 224 C2 discloses a flange gasket for a pipeline, in which an U-shaped sealing lip that points into the interior of the pipeline is integrally formed onto an inner gasket ring of rubber or plastic.  
     BRIEF SUMMARY OF THE INVENTION  
      The invention is based on the objective of realizing a flange gasket of the initially cited type in such a way that it can be attached to a flange in a captive fashion, and that the flange gasket ensures a reliable seal on a fixing screw that is arranged in a through-opening and serves for mounting the flange on a mounting plate.  
      This objective is attained in that the flange gasket contains a bottom plate with an outer peripheral collar, onto which at least one planar structure is integrally formed such that it is situated above and spaced apart from the bottom plate, in that the integral planar structure forms at least one pocket together with the bottom surface situated underneath, in that openings that lie above one another are provided in the pocket, and in that least one of the openings contains a sealing lip.  
      Advantageous embodiments of the invention are disclosed in claims  2 - 9 .  
      The main advantage attained with the invention is that a flange gasket of this type can be attached, for example, to a rectangular flange in a captive fashion, wherein pocket-shaped structures formed in the corner regions of the flange gasket protrude over the corner regions of the flange. This simplifies the handling during the installation, and the flange gasket is also held on the flange during the disassembly. The pocket-shaped structures contain openings that are aligned with the through-openings of the flange or a housing to be mounted, respectively. Fixing screws are then inserted into these openings, and said fixing screws are advantageously held in the region of the openings due to their relatively small diameter in comparison with the diameter of the fixing screws. In this case, the opening of the flange gasket that lies on the flange contains a peripheral bead-like elevation that is directed toward the screw head and a funnel-shaped opening that extends over the material thickness of the flange gasket.  
      A sealing lip is provided in the outlet region of the funnel, wherein the design of the sealing lip may differ in dependence on the aperture angle of the funnel that may lie between a relatively obtuse angle and a relatively flat angle. When a flat angle is chosen, the sealing lip is designed with a very thin outlet such that the material is able to a very tightly adjoin the bolt of the screw. In this respect, the inside diameter of the sealing lip should always be smaller than the diameter of the fixing screw in order to achieve a more or less tight contact. Consequently, a very tight seal of the flange including the openings for the fixing screws can be achieved depending on the respective application. It is also advantageous to provide a web at least on the longitudinal side of the flange gasket, wherein said web extends along the flange to be mounted and thusly reinforces and holds the flange gasket in an optimal position. Since the flange gasket consists of a moulded part, no waste products are accumulated during its manufacture. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      One embodiment of the invention is illustrated in the figures and described in greater detail below. The figures show:  
       FIG. 1 , a plug-type connector housing with a flange gasket;  
       FIG. 2   a , a perspective representation of a flange gasket with four individual pockets;  
       FIG. 2   b , a perspective representation of a flange gasket with a peripheral pocket;  
       FIG. 2   c , a perspective representation of a flange gasket with two pockets on the narrow sides;  
       FIG. 3   a , an enlarged detail of a sealing lip of the flange gasket;  
       FIG. 3   b , a variation of the sealing lip;  
       FIG. 3   c , another variation of the sealing lip, and  
       FIG. 4 , an enlarged sectional representation of an installed flange gasket. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  shows a perspective representation of a plug-type connector housing  1  with a peripheral housing flange  2 , to which a flange gasket  10  according to the invention is attached in a captive fashion. The flange gasket contains a bottom plate  11  with a perpendicular collar  12  integrally formed thereon, as well as openings  16  that are aligned with the through-openings  4  in the corner regions of the housing flange. The bottom surface  11  contains sealing webs  27  that not only serve for stabilizing the flange gasket, but also for sealing the outer region relative to the inner region with the opening  25 .  
       FIGS. 2   a - c  show perspective representations of different variations of the flange gasket  10 . The flange gasket  10  according to  FIG. 2   a  consists of a flat bottom plate  11  that is manufactured from an elastic material and contains a cutout  25 , as well as a perpendicular collar  12  that is integrally formed onto the bottom plate and provided with integral planar structures  13  in the corner regions. The integral planar structures are spaced apart from and arranged above the bottom plate, wherein the planar structures respectively form one pocket  14  in the corner regions of the flange gasket together with the bottom plate. The pockets  14  contain openings  16 ,  17  that are aligned with the through-openings  4  in the housing flange  2 .  
      The figure also shows a bead-like elevation  19  that peripherally extends around the upper opening  16  and is described further below. The flange gasket can be attached in a captive fashion to a correspondingly designed housing flange  2  by means of these pockets.  
       FIG. 2   b  shows a variation of the flange gasket, in which an integral planar structure  13  extends peripherally around the gasket such that a peripheral pocket  15  is formed and the housing flange is completely surrounded by and covered with a flange gasket of this type.  
       FIG. 2   c  shows another variation of the flange gasket, in which a continuous planar structure  13  is integrally formed onto both narrow sides, wherein the integral planar structures form a corresponding pocket  15  with an opening  16  for attaching the gasket to a corresponding housing flange.  
       FIGS. 3   a - c  respectively show enlarged sectional representations of differently designed pockets  14  in the corner regions of the flange gasket  10 . These figures show the axially aligned openings  16 ,  17  that lie on top of one another, wherein the lower opening  17  has a larger diameter than the upper opening. The upper opening  16  is realized in such a way that a peripheral elevation  19  is formed, wherein a tapered funnel  20  extends downward to a sealing lip  22  from said peripheral elevation. The invention proposes that the inside diameter of the sealing lip  22  is smaller than the bolt diameter  32  of a fixing screw  30  for mounting the flange gasket, for example, on a mounting plate  7 . The tapered shape of the sealing lip  22  initially causes the fixing screw  30  to be held therein in a captive fashion.  
       FIG. 3   b  shows a variation of a sealing lip  22  according to  FIG. 3   a , in which the funnel  21  has a significantly flatter angle.  
       FIG. 3   c  also shows a variation, in which the funnel  21  is realized with a flat angle, wherein the sealing lip  23  is arranged, however, underneath the level of the lower material boundary of the integral planar structure  13 .  
       FIG. 4  shows a highly enlarged detail of a flange gasket  10  that is installed between the plug-type housing  1  and the mounting plate  7 , wherein the pocket  14  encompasses the housing flange  2 . The fixing screw  30  was already inserted into the through-opening  4  of the housing flange  2  during the preassembly, wherein the screw is held in a captive fashion by the sealing lip  22 . During the initial mounting of the plug-type housing  1  on the mounting plate  7 , the sealing lip  22  according to  FIG. 3   a  that is directed toward the screw bolt  32  tightly adjoins the screw bolt when the fixing screw  30  is inserted, namely because the sealing lip has a smaller diameter than the fixing screw. Subsequently, the fixing screw is inserted into the through-opening  5  in the mounting plate  7  and tightened with the aid of the washer  38  and the lock nut  36 . The part of the integral planar structure  13  of the flange gasket that lies on the housing flange  2  is provided with a bead-like peripheral elevation  19  that is directed toward the upper washer  38  and increasingly compressed between the washer  38  and the contact surface between the flange and the screw bolt when the screw connection is tightened. The sealing lip  22  is simultaneously pressed against the screw bolt and the flange gasket becomes increasingly tighter toward the through-opening. Consequently, it is ensured that no environmental influences can penetrate into the interior of the housing  7  via the through-openings  4 , wherein a degree of protection in excess of IP 65 is achieved.