Abstract:
A pipe fitting includes a body having sockets for receiving pipes therein and a composite gasket housed within a circumferential gasket retention housing integral with the socket. The composite gaskets include a V-shaped carrier of relatively stiff plastic having an elastomeric seal portion bonded thereto.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a Continuation-in-Part of U.S. patent application Ser. No. 10/313,298 filed Dec. 6, 2002 and currently pending. Application Ser. No. 10/313,298 is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a pipe fitting and gasket assembly for conducting fluid flow.  
         [0004]     2. Disclosure Information  
         [0005]     Fluid conducting pipes have been available with slip fittings for a number of years. Some fittings with slip fits use an external nut to tighten a packing on the inserted pipe. This mechanism, however, requires labor and additional parts and may be awkward to install, particularly in below ground or otherwise confined spaces. Other types of slip fittings, particularly those used in applications such as drain or sewer pipes, have used slip fittings without the need for tightening a nut. For example,  FIG. 2  illustrates a prior art seal in which plastic band  202  is combined with a very large elastomeric part  200 . Unfortunately, the gasket or seal of  FIG. 2  is quite expensive due to the need to provide this large elastomeric body.  
       SUMMARY OF THE INVENTION  
       [0006]     A pipe fitting for telescopically receiving at least one pipe includes a body having a generally cylindrical wall defining an opening for receiving a pipe. A circumferential gasket retention region projects radially outwardly from a portion of the generally cylindrical wall, so as to define an annular gasket retention race or channel. A gasket having a generally V-shaped cross-section is provided within the gasket retention channel and includes a V-shaped carrier portion of relatively stiff plastic and an elastomeric seal-forming portion. The gasket is adapted to be radially and elastically compressed by a pipe inserted axially into the fitting body. In a preferred embodiment, the V-shaped carrier portion and elastomeric sealing portion may be co-molded, with the elastomeric portion being formed from a resilient material and the V-shaped carrier being formed from a relatively stiffer material. In this manner, the inventive gasket seal may be easily and economically produced by co-molding.  
         [0007]     The gasket of the present invention has an outer leg adapted to abut the floor of the gasket retention channel. The gasket further has an inner leg hinged to the outer leg with the inner leg being adapted to abut a pipe inserted into a fitting into which the gasket has been seated.  
         [0008]     The elastomeric seal portion of the inner leg of the gasket preferably includes an annular sealing flap or ring extending radially inwardly from the gasket body such that a pipe inserted telescopically into the fitting compresses the annular sealing ring while simultaneously elastically deforming the V-shaped carrier.  
         [0009]     It is an advantage of the present invention that a pipe fitting and gasket assembly according to this invention produces superior results in terms of performance under vacuum and resistance to pressure conditions.  
         [0010]     It is a further advantage of the present system that leak tight sealing is provided without the need for the use of special tools for assembling various pipe fittings.  
         [0011]     Other advantages, as well as objects and features of the present invention, will become apparent to the reader of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a perspective view of a pipe fitting having a sealing system according to present invention.  
         [0013]      FIG. 2  illustrates a prior art gasket assembly.  
         [0014]      FIG. 3  illustrates a gasket assembly according to one aspect of the present invention.  
         [0015]      FIG. 4  illustrates a pipe fitting and joint assembly according to one aspect of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     As shown in  FIG. 1 , pipe fitting  10  (typically formed of PVC) has generally cylindrical wall  12  with a plurality of generally cylindrical sockets or openings  14  for receiving pipes (such as pipe  52  in  FIG. 4 ) inserted into fitting  10 . Gasket  18  is used for sealing pipe  52  in fitting  10 . Gasket  18  is inserted into and retained by a gasket retention portion  16 . As shown with more specificity in  FIG. 4 , gasket retention portion  16  defines an annular gasket retention channel  17  into which a gasket  18  maybe snapped so as to retain gasket  18  both axially and radially.  
         [0017]     The details of gasket  18  in the preferred embodiment are shown in  FIG. 3 . Gasket  18  is preferably a composite of two types of molded materials, but may be a single type of material fabricated to provide two different hardnesses. V-shaped carrier portion  20  serves essentially as a spring element for gasket  18  and preferably comprises polyethylene. Those skilled in the art will appreciate in view of this disclosure that the material for V-shaped carrier portion  20  may be selected from a variety of other known engineering resin materials such as polypropylene, polystyrene, ABS, polyamide, polycarbonate, polyesters (polyethylene terepthalate and polybutylene terepthalate), polyvinylchloride or other plastics. Included also are fiber reinforced plastics, for example, glass-fiber reinforced polypropylene or polyamide, and stiff thermoplastic vulcanizates (TPV). The materials for V-shaped carrier portion  20  may also be selected from other materials, such as, thermoplastic elastomer polyolefins, hydrogenated or unhydrogenated styrene block copolymers, thermoplastic polyurethane elastomers, blends thereof, and plasticized polyvinylchloride. It will be understood from the present disclosure that the material from which V-shaped carrier portion  20  is formed should be stiff, yet must flex at hinge portion  26  (best seen in  FIG. 3 ) repeatedly without cracking or breaking. In other words, V-shaped carrier portion  20  biases inner leg  24  against pipe  52  as will be explained more fully hereinafter. Most preferably, V-shaped carrier portion  20  should have a hardness (Shore D durometer) of between about 40 to 50. A particularly suitable stiff material that retains flexibility, is the hard TPV product SANTOPRENE® 203-50 from Advanced Elastomer Systems, L.P., which has a Shore D durometer level of 50. This product is a blend of polypropylene and cross-linked EPDM rubber.  
         [0018]     V-shaped carrier portion  20  includes outer leg  22  which biases gasket  18  against the outer circumference or floor of the annular gasket retention channel  17  defined by gasket retention housing  16 ; inner leg  24  biases against pipe  52  inserted into fitting  10 . As stated, V-shaped carrier portion  20  has a hinge portion  26  which allows the V to flex. Referring to  FIG. 4 , pipe  52  is telescopically inserted into fitting  10 . In turn, gasket  18  is radially compressed by pipe  52  when pipe  52  is inserted into fitting  10 . In other words, the V-shaped nature of gasket  18  along with the stiffness of carrier portion  20  creates a spring biasing effect. V-shaped carrier  20  preferably also has a plurality of annular bump stops  28  which help prevent carrier portion  20  from collapsing or deforming more than a predetermined amount under radially directed stress imposed by pipe  52  inserted in the fitting  10 . Additional annular beads, such as bead  53  of  FIG. 3  may be provided to further control the biasing force of gasket  18 .  
         [0019]     Elastomeric seal portion  32  comprises an integral part of gasket  18 . Elastomeric seal portion  32  may be made of a number of elastomeric materials known to those skilled in the art. It will be recognized from the present disclosure that the material used to form elastomeric seal portion  32  is preferably an elastomer or elastomerized material, most preferably having a hardness (Shore A durometer) of from about 45 to about 65 and a more preferably from about 50 to about 60. Elastomeric seal portion  32  has an outer portion  34  which bears against the floor of gasket retention housing portion  16 . Elastomeric seal  32  also has an inner portion  36 , which in this embodiment (with the remainder of elastomeric seal  32 ), is bonded to V-shaped carrier  20 . Co-molding or co-extrusion of carrier  20  with elastomeric seal portion  32  is expected to comprise an economical process for manufacturing gasket  18 . It should be noted that the amount of elastomeric material needed to fabricate a gasket according to the present invention is much less than that required for the prior art gasket illustrated in  FIG. 2  due to the “V” cutout. As a result, the cost savings offered by the inventor&#39;s gasket may be considerable. As stated, alternatively, carrier  20  and sealing portion  32  may be made of the same type of material, so long as carrier  20  is stiffer than sealing portion  32 .  
         [0020]     Elastomeric seal portion  32  includes an annular sealing ring or projection  38  which extends radially inwardly from inner portion  36  of elastomeric seal  32 , such that a pipe inserted telescopically into fitting  10  compresses and deflects annular sealing ring  38  while simultaneously elastically deforming V-shaped carrier  20  as best shown in  FIG. 4 .  
         [0021]     In order to assure that debris which may be adhering to the outside of pipe  52  does not interfere with annular sealing ring  38 , elastomeric seal  32  is further equipped with scraper ring or wiper  40  which extends radially inwardly from inner portion  36  of seal  32 , so as to physically remove deposits such as dirt or small rocks from the surface of a pipe as it is inserted into fitting  10 . This assures an excellent seal between the outer wall of the pipe being inserted and elastomeric seal  32 . Alternatively, the scraper ring may be formed on V-shaped carrier  20 . Under vacuum conditions, wiper  40  also helps provide a tight seal.  
         [0022]     In exemplary embodiments, the elastomeric material of seal portion  32  may comprise one or more thermoplastic elastomers (TPE), and mixtures thereof. Particularly suitable thermoplastic materials will include dynamically vulcanized TPE, or thermoplastic vulcanizates (TPV). Particularly suitable are the polyolefin TPV compounds comprising at least one non-crosslinked polyolefin thermoplastic phase and at least one cross-linked polyolefin rubber phase. Other suitable TPEs include the thermoplastic elastomer polyolefins (TPO) without a cross-linked phase, such as homopolymers or copolymers of propylene and ethylene blended with ethylene-propylene rubber; hydrogenated or unhydrogenated styrene block copolymers (SBC), particularly SEBS; and blends of such copolymers, both those considered thermoplastic and those exhibiting the properties of thermoplastic elastomers; and blends of polyolefins, or blends of one or more of them, with SBC copolymers. Thermoplastic polyurethane elastomers will also be suitable, alone or in blends with other thermoplastics or thermoplastic elastomers. Also, plasticized polyvinylchloride can be used as the elastomeric material. Such materials are well-known in the art, see,  Thermoplastic Elastomers ( 2 nd Ed.),  Ch. 3, G. Holden, N. Legge, et al (Hanser Publishers, 1996). In a most preferred embodiment the elastomeric material will comprise SANTOPRENE® 101-55W185, a TPV product of Advanced Elastomer Systems, L.P., having a Shore A hardness of 55.  
         [0023]     Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention. It is intended that the invention be limited only by the appended claims.