Abstract:
A sealing apparatus includes a sealing arrangement and a groove in a base. The sealing arrangement may comprise an o-ring and a grounding gasket where both the o-ring and the grounding gasket partially protrude in a longitudinal direction from the groove. Thus, the grounding gasket, which is equipped with ends that can be pulled out of the groove, can be removed from the groove by a pulling force. This leaves the o-ring accessible for removal or maintenance at a much lower cost in terms of manufacturing and operational costs. The sealing arrangement may also include inner and outer o-rings which seal a fluid flow from the atmosphere.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is related to pending International Application No. PCT/US01/45860, filed on Dec. 19, 2001. This application is related to, and claims priority to, U.S. Provisional Application No. 60/398,729, filed Jul. 29, 2002. The contents of these applications are incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to a sealing apparatus comprising at least one o-ring and a groove capable of retaining the o-ring and secondary sealing rings or grounding gaskets adjacent to the o-ring.  
         DISCUSSION OF THE BACKGROUND  
         [0003]    In many hardware configurations, maintaining a seal between components is an important design consideration. For example, in plasma processing at low pressure, the connection of various parts to form a vacuum-tight process chamber requires sealing members to maintain the vacuum integrity at these connections.  
           [0004]    Typically, a sealing member can comprise a simple o-ring configuration. Generally, where two connecting parts meet, each part is equipped with a surface that cooperates with the surface of the other part in a known way. At least one of these surfaces includes a sealing member. The sealing member typically includes an o-ring, secured within a groove. Where conductive parts are connected, the connection between these parts also requires a grounding gasket to act as a circuit bridge. The grounding gasket also requires a groove.  
           [0005]    As illustrated in FIG. 1 for the connection of two cylindrical components, these grooves  5 ,  3  are substantially circular, centered about a center of the surface, and contained within the surfaces of at least one of the mating parts  1 . As shown in FIG. 2, the groove  5  securing the o-ring  6  can comprise a dovetail or a rectangular cross section. As such, the groove  5  will be narrower where the groove is coplanar with the mating surface  1 A. Therefore, dovetail grooves have the advantages of being able to secure an o-ring inside, while allowing an upper portion of the o-ring to protrude out of the groove and contact the surface of another mating part and allowing the o-ring to spread out within the groove under compression.  
           [0006]    Thus, when the mating parts are brought together, a seal of an interior region between the parts from an exterior region is formed where the o-ring  6  contacts the surfaces of the groove and the second mating part. Where an electrical connection must be maintained between the parts, it is known to use a grounding gasket  4 . The grounding gasket  4  contacts both mating parts as the o-ring  6  is compressed, acting as a circuit bridge and electrically coupling both parts. In general, a separate groove  3 ,  5  is formed for each o-ring  6  and each grounding gasket  4 , respectively.  
           [0007]    However, the use of known dovetail grooves also usually requires a groove relief in order to be able to extract the o-ring. A groove relief is a discontinuity in the groove at a particular point, and appears wider than the rest of the groove. Without the groove relief  7 , removal of the o-ring is more difficult. In fact, the removal of the o-ring  6  from groove  5  without the groove relief  7  can cause damage to the o-ring  6  and/or the groove  5  that may disrupt the vacuum integrity of the mated components.  
           [0008]    Moreover, removal of an o-ring in a groove  5  having a groove relief  7  requires that a narrow prying tool be inserted into the groove relief  7 . An applied torque then forces a portion of the o-ring  6  out of position. Once a portion of the o-ring  6  is out of position, the remainder can be forcefully pulled out of the groove  5 .  
           [0009]    Ultimately, repeatedly prying  0 -rings  6  out of grooves  5  in mating surfaces is a harmful practice since the prying action leads to the wear and tear of the various parts. Additionally, the manufacture of groove reliefs increases labor and machining costs and is not always chosen. For mating surfaces requiring multiple seals and/or mating surfaces requiring seals and additional grooves for grounding gaskets, the need for extra grooves and groove reliefs creates a need for the mating surfaces to be larger, thus leading to increases in materials costs.  
         SUMMARY OF THE INVENTION  
         [0010]    Consequently, there exists a need for a sealing apparatus that reduces machining costs and the sizes of mating surfaces as compared to known systems. According to one embodiment, the present invention includes at least one o-ring and a groove capable of retaining the o-ring and secondary sealing rings or grounding gaskets. This structure decreases machining costs and makes maintenance and manufacture easier.  
           [0011]    Therefore, in a preferred embodiment of the invention, a sealing and grounding apparatus comprises an o-ring and a grounding gasket contained within a single groove, disposed within a surface of a first mating part, capable of retaining the o-ring and the grounding gasket without groove reliefs.  
           [0012]    Additionally, in a connection of two members having mating surfaces where at least one of the members separates a first region from a second region, a need also exists for a sealing apparatus comprising at least two  0 -rings and a groove. The groove of the present invention retains the at least two o-rings.  
           [0013]    Thus, in a second preferred embodiment of the present invention, a sealing apparatus comprises at least two  0 -rings and a groove, disposed within a surface of a mating part, wherein the groove can have groove reliefs. The  0 -rings integrally contact each other and the groove. The  0 -rings both partially protrude out from the groove and are configured to contact a second mating surface, wherein a leak check port is disposed between the respective o-ring contact points with the second mating surface. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    A more complete appreciation of the invention and many of the attendant advantages thereof will be readily apparent with reference to the following detailed description particularly when considered in connection with the accompanying drawings, in which:  
         [0015]    [0015]FIG. 1 is a perspective view of the background art;  
         [0016]    [0016]FIG. 2 is an enlarged perspective view of a cutaway in the background art;  
         [0017]    [0017]FIG. 3 is a perspective view of a preferred embodiment of the invention;  
         [0018]    [0018]FIG. 4 is an enlarged perspective view of a cutaway of the embodiment of FIG. 3;  
         [0019]    [0019]FIG. 5 is a cross-sectional view of the embodiment of FIG. 3;  
         [0020]    [0020]FIG. 6A is a perspective view of an uncurled grounding gasket;  
         [0021]    [0021]FIG. 6B is a perspective view of the grounding gasket of FIG. 6A once the grounding gasket has been curled;  
         [0022]    [0022]FIG. 7 is a perspective view of a grounding gasket being removed from the groove prior to removing the adjacent o-ring seal; and  
         [0023]    [0023]FIG. 8 is an enlarged cross-sectional view of a second preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, a sealing apparatus includes a single groove formed within a mating surface which contains an o-ring capable of sealing a first area between mating parts from a second area. This groove may additionally contain at least one of: a grounding gasket capable of maintaining a circuit bridge between mating parts, and a second o-ring to create seals that supplement the seals created by the first o-ring.  
         [0025]    Referring to FIG. 3, a first mating part  11  has a surface  11 A and mates with a second mating part  12  having a second surface  12 A. A groove  13  is formed within the surface  11 A of the first mating part  11 . As shown in FIG. 4, the groove  13  has a substantially dovetail shaped cross-section. Thus, if the groove  13  were divided in half along the length of the groove  13 , each half would have a base  20  and a wing  22 , and a groove centerline  24  can be defined. In general, the wing  22  extends from the base  20  of the groove  13  to the surface  11 A, and comprises a first wing surface  26  (to the left of centerline  24  in FIGS. 4 and 5) extending between a first inner edge  28  and a first outer edge  30  and a second wing surface  32  (to the right of centerline  24  in FIGS. 4 and 5) extending between a second inner edge  34  and a second outer edge  36 . As shown in FIG. 4, the first and second inner edges  28 ,  34  of each half taper away from each other; i.e. extend a greater distance from centerline  24  than the first and second outer edges  30 ,  36 . The first and second inner edges  28 ,  34  of each half are coupled to base  20 , and the first and second outer edges  30 ,  36  of each half are coupled to surface  11 A of the mating part  11 .  
         [0026]    With reference to FIG. 5, the distance from the first outer edge  30  of the first half of the groove to the second outer edge  36  of the second half of the groove along a radial axis is X 1 . At the base  20 , from the first inner edge  28  to the second inner edge  34  along a radial axis, the groove  13  has a width X 2 . Typically, X 1  is less than X 2  for a dovetail cross-section. From the base  20  to the mating surface  11 A, the groove  13  has a height H 1 .  
         [0027]    As will be discussed below, in the embodiment of FIG. 5, the groove  13  contains an o-ring  16  and a grounding gasket  14  either inside or outside and adjacent to the o-ring  16 . When normally compressed, the total cross-sectional area of the o-ring and the grounding gasket will be between the values of X 1  and X 2 . Each will be approximately H 2  in height, where H 2  is greater than or nearly equal to H 1 . Therefore, the groove  13  will securely contain the o-ring  16  and the grounding gasket  14  while allowing each part to protrude out of the groove  13  where they contact the second mating part  12 . Note that even when uncompressed, the invention anticipates that the groove will securely contain the o-ring  16  and the grounding gasket  14 .  
         [0028]    Since H 2  is greater than H 1 , when the parts are mated, an infinitesimally small space is formed between the two mating parts having a height H 3 , where H 2 −H 1 =H 3 , and the distance H 3  approaches zero. The space to one side of the groove  13  is sealed from the space to an opposite side of the groove  13 , and since the grounding gasket  14  is electrically coupled with the first and second mating parts  11 ,  12 , the second mating part  12  is electrically coupled to the first mating part  11  with the aid of the grounding gasket  14 .  
         [0029]    An o-ring  16  is preferably substantially circular in the azimuthal direction centered about the first mating part  11 . Thus, the o-ring  16  fits within and is retained by the groove  13 . The cross-section of the o-ring  16  is preferably circular. Alternately, other non-circular cross-sections are possible.  
         [0030]    The o-ring  16  is typically comprised of an elastomer material (e.g., fluorosilicone, nitrile, fluorocarbon, silicone, neoprene, ethylene propylene, etc.). These materials are generally selected per application based upon the following physical characteristics: resistance to fluid, hardness, toughness, tensile strength, elongation, o-ring compression force, modulus, tear resistance, abrasion resistance, volume change, compression set, thermal effects, resilience, deterioration, corrosion, permeability, coefficient of friction, coefficient of thermal expansion, outgas rates, etc.  
         [0031]    A grounding gasket  14  is normally straight and can be conformed to fit into the groove  13 . Alternately, an o-ring shape can be used. Preferably, the cross-section of the grounding gasket is circular. Alternately, other non-circular cross-sections are possible.  
         [0032]    The grounding gasket  14  (e.g., a Spira Shield Quick-Shield commercially available from Spira Manufacturing Company) comprises an inner layer of a compressible material (e.g., fluorosilicone, neoprene, PVC cord, silicone, etc.) and an outer conductive layer (e.g. beryllium-copper or stainless steel plated with gold, tin, or tin-lead). The material serving as the inner layer of compressible material and the material serving as the outer conductive layer are generally selected per application using some of the physical characteristics described above.  
         [0033]    Since the grounding gasket comprises a conductive outer layer, where the first and second parts are also conductive, the connection between the parts via the grounding gasket can form an electrical bridge.  
         [0034]    As noted above, removing o-ring  16  from a conventional groove  13  required either the installation of groove reliefs or risking damage to the edges of the groove when prying the o-ring out of the groove. As a result of this invention both issues have been addressed. With reference to FIGS. 6A, 6B, and  7 , when repairing or replacing component parts, the process of removing the o-ring  16  and the grounding gasket  14  is simplified, and requires that an end  14 A,  14 B be pulled out of the groove  13 . This is made possible not only by the presence of an accessible end, but also by the fact that the grounding gasket, as noted above, has certain compressible properties which allow the grounding gasket to be manipulated.  
         [0035]    With the grounding gasket removed, the o-ring  16  is exposed within the groove. As a result, removing the o-ring is achieved by pulling or pushing a particular section of the o-ring out of position.  
         [0036]    A second embodiment of the present invention anticipates that a connection between two parts requires a seal capable of sealing a first region from a second region using two sealing elements, and providing access to a third region between the two sealing elements in order to facilitate leak checking the sealing elements. In an embodiment of the present invention, the first region comprises a first fluid, the second region comprises a second fluid, and the third region comprises a third fluid. By definition, the term fluid can refer to a material in either a liquid phase or a gaseous phase. For example, the first fluid can be a coolant such as Fluorinert, the second fluid can be a vacuum, and the third fluid can, in general, be air at atmospheric pressure, when not leak checking the seals, and a gas such as helium from a gas supplying member, when leak checking the seals.  
         [0037]    Thus, with reference to FIG. 8, a first element  101  having a first wall surface  103 A, a second wall surface  103 B, and a first mating surface  103 C is attached in a known way to a second element  102  having a second mating surface  105 . The first element  101  can, for example, separate a first fluid  106  in a first region  107  from a second fluid  108  in a second region  109  using two o-rings  110 A and  110 B secured within a single groove  111 . Additionally, a third region  112  can be provided between the two o-rings  110 A,  110 B, and can be coupled to a third fluid  113  from a gas injection point  116  through a leak-check port  115 . Methods of using leak check port  115  to check seal integrity and, if necessary, determine the location of a leak are well known to those skilled in the art of vacuum processing.  
         [0038]    With continuing reference to FIG. 8, the groove  111  is shown containing first and second o-rings  110 A and  110 B. In accordance with this embodiment the structure of the groove and the o-rings are substantially the same in terms of their physical and structural properties as in FIGS.  4 - 7 . That is, the groove  111  is just wide enough so as to secure both o-rings inside of it and high enough so as to allow them to protrude from the top of the groove. Therefore, when the o-rings are compressed during a connection between first and second members  101  and  102 , a space is created through which the fluid can flow only up to the seals created by the o-rings.  
         [0039]    Further, removal of the  0 -rings is possible by removing one o-ring and thereby exposing the other. For example, a groove relief (not shown) can be employed in the single groove  111  in order to permit easy removal of both o-rings  110 A and  110 B.  
         [0040]    Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.