Bidirectional gasket having water energizing pockets

Abstract

A bidirectional gasket providing a water-tight seal between an opening in a manhole assembly and a pipe extending into said opening, comprises a T-shaped anchoring portion for embodiment in a manhole opening. A substantially A-shaped pipe engagement portion is joined to the anchoring portion by a slender connecting web facilitating bending of the gasket. The A-shaped portion has "legs" and recesses which form water pockets preventing water from entering. The durometer of the gasket material enhances the water-tight seal of the legs with increasing water pressure. The pipe engaging portion accommodates a greater outside pipe diameter compared with conventional connectors due to reduced volume, by providing voids within the connector together and a lower durometer of gasket material. The gasket has enhanced ability to accommodate diameter deflection or ovation in rigid and flexible pipe materials. The A-shaped profile allows for greater angular deflection and/or pipe misalignment compared with conventional connectors. The gasket apex has a recess to locate the voids which, in addition to enhancing mechanical softness of the gasket, also provides the ability to increase gasket compression by introducing a liquid filler into the voids. Tapered projections near the apex wipe the external periphery of a pipe upon insertion and also contribute to the compression of the nose portion of the connector. The gasket may be molded or formed from an elongated extrusion joined at its ends to form an annular gasket.

What is claimed is: 
     
       1. A bidirectional annular gasket for providing a water-tight seal between an opening in a barrier wall and a pipe inserted into said opening, said gasket comprising a ring of elastomeric material having a substantially uniform cross-section along its circumferential length, said cross-section comprising a T-shaped anchoring portion including a radially-outwardly directed foot portion and a neck portion integral with said foot portion and extending at right angles and radially inward therefrom to form said T-shaped anchoring portion and a head portion extending radially inward of said foot portion for engagement with the exterior of said pipe; said head portion having a substantially A-shaped configuration defined by a wide end tapering to a narrow tip, with the wide end of said A-shaped configuration being positioned adjacent said anchoring portion and a narrow tip forming an apex of said head portion and, prior to insertion of a pipe, extending radially inwardly from and being remote from said anchoring portion;   the head portion, prior to insertion of a pipe, being substantially symmetrical about a plane passing through the center of the head portion and aligned with said radial direction;   the wide end of said head portion being provided with a recess defining a pair of legs extending diagonally outward and away from the main body of said head portion;   a connecting web joining said A-shaped configuration and said anchoring portion and being integrally joined at a first end to the wide end of said A-shaped configuration substantially at midpoint of said recess and at a second end to a radially inward end of said neck portion; and   said connecting web dividing said recess into a pair of pockets on opposite sides of said web.   
     
     
       2. The gasket of claim 1 wherein the thickness of said connecting web, measured in a direction perpendicular to said plane, is less than the thickness of said neck portion measured in said perpendicular direction to facilitate flexing and bending of said connecting web upon insertion of a pipe into said gasket when the diameter of the pipe is greater than the diameter defined by the apex of said gasket head portion causing said gasket to bend in a region of said connecting web. 
     
     
       3. The gasket of claim 1 wherein .Iadd.said head portion is provided with first and second cavities each of substantially circular cross-section and spaced from one another in a radial direction to define a wall between said cavities transverse to said plane, each of said cavities extending substantially continuously about the circumference of the gasket and  said A-shaped portion is further provided with a recess at the tip of said A-shaped portion to facilitate location of said cavities and to facilitate insertion of a hypodermic-type needle for insertion of a liquid material into at least one of said cavities to alter .[.the.]. compressibility of the gasket. 
     
     
       4. A bidirectional gasket for use in forming a fluid-tight seal between a pipe and an opening in a barrier wall through which said pipe passes, comprising: an annular member of elastomeric material having a tubular head portion of a substantially A-shaped cross-section defined by a wide end and having tapering sides tapering to a narrow tip and a foot portion comprising a base flange portion and a neck portion of substantial thickness integrally joined to a mid-region of said base flange portion to form a substantially T-shaped anchoring portion for embodiment within a cast material forming said barrier wall;   said head portion tapering sides being substantially symmetrical about a plane passing through a longitudinal axis of the said A-shaped portion;   a connecting web extending between said neck portion of said foot portion and the wide end of said A-shaped head portion;   said A-shaped head portion having .[.a plurality of.]. recesses at the wide end thereof .Iadd.and arranged .Iaddend.on opposite sides of said connecting web and a pair of flanges, each extending diagonally away from its associated recess at an angle substantially equal to the angle formed by the tapering sides of said A-shaped cross-section, said recesses forming self-energizing water pockets to cause the flange of the associated water pocket which may be filled with water to exert a greater compression force against an engaging surface of a pipe inserted through said gasket as a function of increasing water pressure applied upon said water pocket; and   said annular member being formed from .Iadd.a linear extrusion, .Iaddend.a length of said linear extrusion being curved and joined at its ends to form said annular .[.ring.]. .Iadd.member. .Iaddend.   
     
     
       5. The gasket of claim 4 wherein the thickness of said connecting web is substantially less than the thickness of said neck portion to enhance the bending flexibility of said gasket. 
     
     
       6. Th gasket of claim 4 wherein each of said recesses has a curved concave surface portion to facilitate the intimate engagement of its associated .[.flap.]. .Iadd.flange .Iaddend.with a pipe due to increasing water pressure. 
     
     
       7. A bidirectional gasket for use in forming a fluid-tight seal between a pipe and an opening in a barrier wall through which said pipe passes, comprising: an annular member of elastomeric material having a substantially constant cross-section comprising a tubular head portion for engaging a pipe and a foot portion comprising a base flange portion and a neck portion of substantial thickness integrally joined to a mid region of said base flange portion to form a substantially T-shaped anchoring portion for embodiment within a case material forming said barrier .[.walls.]. .Iadd.wall.Iaddend.;   said head portion having tapering sides which are substantially symmetrical about a plane passing through a longitudinal axis of said head portion;   a connecting web extending between said neck portion of said foot portion and said head portion;   a pair of recesses provided in said head portion on opposite sides of said connection web for forming water pockets;   said head portion having a pair of integral legs extending away from said head portion in a generally radially outward direction, each leg and connecting web defining sides of an associated recess; and   said water pockets serving as water-tight enhancing means urging the leg of the associated water pocket which may be filled with water to exert a greater compressive force against an engaging surface of a pipe inserted through said gasket as a function of increasing water pressure.   
     
     
       8. The gasket of claim 7 wherein the thickness of said connecting web is substantially less than the thickness of said neck portion and said head portion to enhance the bending flexibility of said gasket. 
     
     
       9. The gasket of claim 7 wherein the length of said legs is greater than the length of said connecting web, said lengths being measured generally along a line passing through the center of said connecting web. 
     
     
       10. The gasket of claim 7 wherein .[.the.]. ends of said legs engage the opening in said barrier wall, prior to insertion of a pipe, and are adapted to selectively engage the pipe when the gasket is deflected due to insertion of a pipe. 
     
     
       11. The gasket of claim 7 wherein .[.the.]. ends of said legs extend a small predetermined distance into annular recesses provided in the opening in said barrier wall and are adapted to selectively snap out of said recesses when the gasket is deflected due to insertion of a pipe. 
     
     
       12. The gasket of claim 7 wherein said legs substantially overlie said connecting web. 
     
     
       13. The gasket of claim 7 wherein said connecting web has a predetermined length, said recesses each having a depth substantially equal to the length of said connecting web.