Pipe coupling gasket insert
BACKGROUND OF THE INVENTION 
     This invention relates to a ring-like, resilient insert which may be optionally used within a conventional pipe coupling gasket mounted within a conventional pipe coupling for connecting adjacent ends of aligned pipes. 
     Conventional pipe couplings which are used to connect the ends of water pipes and the like, which pipes are provided with exterior connection grooves, generally are formed of a circular casing or housing made of two semi-circular segments that are connected together to encircle the adjacent pipe ends. The segments are U-shaped in cross-section with a circular base and inwardly extending legs having free ends that engage within the pipe grooves. Thus, the inner edges of the legs form keys or tenons, which extend within the grooves in the exterior surfaces of the pipes for positively holding the pipe ends together. 
     A conventional rubber-like resilient gasket is arranged around the adjacent pipe ends and within the coupling casing or housing. That is, the two segments that typically form the casing are positioned around the gasket with their legs enclosing the gasket. The gasket typically is formed with lips on the inner ends of the legs for encircling and engaging the adjacent pipe peripheral surfaces. 
     Examples of such couplings are illustrated in my prior U.S. Pat. No. 4,966,395, issued Oct. 30, 1991 for a &#34;Rigid or Flexible Coupling for Pipes&#34; and in U.S. Pat. No. 4,915,418, issued Apr. 10, 1990 to Josef Palatchy for a &#34;Hinged Pipe Coupling&#34;. Other patents illustrate similar types of devices within which the insert of this invention is useful. As indicated in the above mentioned patents, the coupling segments, which are made out of metal, may be bolted together to form the single, circular coupling or may be attached together by suitable hinge configurations and locked together with bolts, etc. 
     When conventional casings are utilized to connect water pipes and similar fluid carrying pipes, it is sometimes necessary to seal the adjacent pipe ends more firmly than is possible using conventional gaskets. In addition, it may be desirable to seal the pipe ends together with a seal which is of a different resiliency than the gaskets typically used. This may be particularly useful in installations where the pipe ends tend to move or flex relative to each other. 
     Thus, attempts have been made in the past to provide C-cross-section shaped resilient gaskets that are utilized within conventional pipe coupling housings, with a central tongue portion, which can extend within or bridge over the slight gap that normally occurs between two aligned pipes that are to be coupled together. An example of this is a coupling gasket formed in a C-shaped cross-section with a central tongue extending inwardly between the spaced apart legs of the gasket. This forms a unitary or integral molded gasket with a central tongue for engaging the adjacent pipe ends. With such construction, rigidifying the tongue sufficiently so that it maintains its position and pressure against the pipes has been accomplished by molding a flat ring within the tongue. The flat ring extends in the axial direction from one side or face of the tongue to the other face. 
     The formation of an integral gasket and tongue, particularly with a flat ring molded within the tongue for rigidity or stability purposes, is relatively expensive. In addition, that construction requires maintaining a relatively large inventory so that gaskets with and without tongues are available in a number of sizes to fit different couplings. That is, the warehouse or manufacturer or the contractor, utilizing such gaskets, must stock double the number of ordinary gaskets that might be kept, because the tongue is needed in some coupling installations, but not in others. That substantially increases inventory expense and, also, the expense of manufacturing because of the need for additional molds for molding the rubber-like gaskets and the need for different size metal reinforcing rings for the tongues. 
     Thus, this invention is concerned with providing a tongue-like insert which may be optionally used. This insert may be manually inserted or removed from a conventional coupling gasket when desired. 
     SUMMARY OF THE INVENTION 
     This invention relates to the provision of a separate tongue-like insert for application within a conventional C-shaped coupling gasket used within conventional pipe couplings for providing an additional seal against the adjacent edges and peripheral edge portions of pipes to be coupled together. The insert may be used whenever desired by manually placing an insert within the gasket. 
     The insert may be formed by extruding long lengths or strips which are cut to pre-determined sizes which are bent into ring shapes. Adjacent portions of the bent ring shapes are adhered together by a conventional adhesive or by heat welding the adjacent ends together. Metal reinforcing rings are formed by extruding the rubber-like plastic material around a wire when the long lengths are extruded. 
     One object of this invention is to form ring-like inserts that provide a tongue within a conventional pipe coupling gasket, which inserts may be manufactured with a single extrusion mold for each cross-sectional size, as contrasted with the numerous molding dies that were required for each cross-sectional size, different diameters, and integral tongue gaskets. Similarly, special fixtures for forming separate metal rings of different diameters for use in reinforcing and stabilizing the tongue of different size coupling are eliminated. 
     Another object of this invention is to provide inexpensive inserts which may be stocked or inventoried along with conventional gaskets and utilized by the contractor whenever a gasket tongue needed simply by inserting the proper size insert within the pipe coupling gaskets as needed on the job of installing pipes within a building. The insert may be pre-bent into a ring or may be bent in a ring at the job site. 
     A further object of this invention is to provide an inexpensive, extruded insert which is reinforced with an internal wire, whose ends need not be fastened together. Rather, the extrusion may be bent into a ring and its opposite ends may be adhesively secured together or secured together by heat welding. The wire ends may be unconnected. 
     An important object of this invention is to provide an inexpensive, optionally useable, gasket tongue for sealing against the adjacent ends of pipes to be coupled, where desired, without the necessity of manufacturing duplicate size gaskets with and without such tongues. 
     These and other objects and advantages of this invention will become apparent, upon reading the following description, of which the attached drawings form a part. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is an elevational view, partially in cross-section, showing a conventional pipe coupling for connecting adjacent pipe ends. 
     FIG. 2 is a cross-sectional view taken on arrows 2--2 of FIG. 1 showing the coupling fastening adjacent, pipe ends together with a typical gasket arranged within the coupling and sealing against the peripheral surfaces of the pipe ends. 
     FIG. 3 is a view of a single coupling segment, taken in the direction of arrows 3--3 of FIG. 1. 
     FIG. 4 is a cross-sectional view, similar to FIG. 2, showing the coupling and gasket and the insert positioned within the gasket. 
     FIG. 5 is an enlarged, fragmentary view of the insert, gasket and coupling engaging and securing adjacent pipe ends together. 
     FIG. 6 is an enlarged, cross-sectional, fragmentary, perspective view of a portion of the insert, showing the wire reinforcement within the insert. 
     FIG. 7 is a view, to a smaller scale, showing the ring-like insert. 
     FIG. 8 is a view similar to FIG. 5, but showing an insert having a modified interior sealing rim for bridging the gap between adjacent pipe ends. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates, in partial cross-section, a conventional circular pipe coupling formed of a circular casing or housing 10 which is channel shaped or C-shaped in cross-section. The casing may be formed of two semi-circular segments 11 and 12, or in some instance, of more than two segments. The casing is arranged around a pair of aligned pipe ends 13 and 14 which are spaced apart by a narrow gap 15. The gap is needed to permit expansion and contraction of the pipes due to normal temperature changes. Each of the pipes is provided with a continuous groove 16 adjacent its respective end. 
     The U-shaped casing or housing 10 is provided with an annular base 19 which is spaced apart from and encircles the pipes. Integral legs 20 extend radially inwardly of the base. Each of the legs terminate in an annular, continuous, end which is narrowed to form continuous keys or tenons 21 that fit into the grooves 16 formed in the pipes. This is illustrated, for example, in FIG. 5. These keys or tenons positively hold the pipes together. 
     The segments 11 may be secured together by bolts. For that purpose, they are each provided with radially outwardly extending hollow lugs 23 which provide sockets 24. Bolt holes 25 are formed in the lugs for receiving fastening bolts 26. The bolts are fastened in place by suitable nuts 27. 
     Although the drawings illustrate the use of lugs on opposite sides of each of the segments, it is anticipated that the segments may be hingedly connected together on one side and bolted together on the opposite side, such as illustrated in the above-mentioned U.S. Pat. No. 4,915,418. 
     A ring-shaped gasket 30 is inserted within the casing 10. The gasket is made of a resilient, rubber-like material which is conventionally molded into a C-shaped cross-section. The gasket is sized to closely fit within the casing 10 so that its base portion 31 is adjacent the annular base 19 of the casing and its legs 32 are adjacent the legs 20 of the casing. 
     The gasket legs are preferable formed with oppositely extending lips 33 having free ends 34 that are spaced apart a short distance. These lips from narrow bands which encircle and engage the peripheral surfaces of the respective pipes for sealing against them. In use, where the pipes carry a liquid, such as water, the liquid in the pipes may flow through the gaps to the gaskets and force the lips into tighter, sealing engagement with the respective pipe surfaces that they engage. 
     The foregoing construction of the casing or housing 10, the interior gasket and the sealing formed by the gasket are conventional. This invention relates to a resilient insert 40 which may be optionally used within the gasket 30. 
     The resilient insert is preferably extruded in a generally triangular cross-sectional shape which may have rounded apices. That is, it is formed with a relatively wide base 41, which engages against the interior surface of the gasket base 31, and a narrowed, rim portion 42 which extends between the free ends of the gasket lips 33. Preferably, the side walls defining the insert are provided with annular depressions 43 (see FIG. 6.). 
     The insert is molded in long strips which are cut to pre-determined lengths which are bent into desired diameters. In the extrusion process, a metal wire is inserted to form a metal ring 45 when the extruded length is bent into a ring. The metal ring, in effect, is arranged within a passageway 46 formed in the insert. 
     The long extrusions may be formed of a suitable resilient or rubber-like material which may be either the same or a different material that is used for the gasket. By way of example, the insert may be made of a relatively harder or relatively softer resilient material than the gasket material to provide different sealing effects and, also, to enable the adjacent pipe ends to move relative to each other while maintaining their sealed relationship. 
     The strips or lengths that are cut from the extrusion may be bent into a ring either at the manufacturing site or at the job site. The adjacent ends of the lengths are adhesively secured together at 47 as illustrated in FIG. 7. Ordinarily, it is not necessary to secure the adjacent ends of the wire 45 together. The adjacent wire ends could be welded to form unitary rings, but for most uses, the forces involved do not require a unitary ring. The wire ring, which is embedded within the rubber-like ring, functions to maintain the shape and stability of the insert even if the wire ends are not secured together. Preferably, the wire is formed in a square cross-sectional shape which is completely embedded within the insert to prevent any contact with liquid flowing within the gasket. 
     The ring-like insert may be cavity molded in a conventional plastic molding machine. However, that requires a separate mold for each diameter ring. Thus, the extrusion method described above is preferred since only a limited number of different cross-sectional size inserts are required for fitting within a much larger number of different diameter gaskets. That is, the same cross-sectional size and shape insert may be formed in larger or smaller rings to fit within different diameter gaskets. That limits the number of extrusion dies that are needed. For example, one, two or three extrusion dies may be sufficient to cover a large number of different gasket sizes. 
     The depressions 43 enable the insert ring to be compressed by pressurized liquid located within the interior of the gasket. This stiffens and holds the insert tongue-lie configuration centered within the gasket and properly positioned for sealing against the pipes. While the depressions may be omitted, preferably the depressions are used for this positioning and stabilizing effect for improving the sealing. 
     In operation, the installer of the pipe system within a building may carry with him couplings of the correct size for the particular diameter of pipes to be installed. Those couplings normally are sold with the correct size gaskets. The installer may also carry a collection of loose insert rings for use where needed. When it is desired to use such an insert for sealing adjacent ends of pipes at their gaps, the installer manually places an insert ring of the required diameter and cross-sectional shape within the particular gasket used for that coupling joint. Then the gasket, with the insert, is slipped over the end of one pipe. Next, the other pipe is slipped into the gasket and insert. After that, the metal coupling is applied around the outside of the gasket and bolted in place. That couples the two pipe ends together. The gasket seals against the peripheral surfaces of each of the adjacent pipe ends and the insert seals against the adjacent pipe ends at the gap (see FIG. 5). 
     Since the insert rings are relatively small in size, compared to the gaskets, and since they are inexpensive, the installer may carry an assortment of such rings for use with any particular coupling. 
     For some couplings, it is desired to utilize an insert which bridges the gap between adjacent pipes, rather than fitting between the pipe ends. For that purpose, as illustrated in FIG. 8, a modified insert 50 may be used. This is essentially the same in construction as the insert 40, except that its inner rim 51 is flatter and wider than the rim 42 on the insert 40. The wider rim 51 spans over the gap and encircles, without necessarily fitting between the pipe ends. Otherwise, the operation and usage of the modified insert is the same as the insert previously described. 
     This invention may be further developed within the scope of the following claims.