Plastic pipe coupler with internal sealer

A coupling for securing a plastic pipe. The coupling has a rigid hollow coupling shell with a passageway through it. A rigid stiffener tube is positioned internally of the shell, the stiffener tube having an external diameter slightly less than the internal diameter of the pipe. The stiffener tube has an external circumferential groove spaced from its outer end. A toroidal elastomeric seal is positioned within the stiffener tube circumferential groove. When a pipe end portion is inserted into the coupler shell, the stiffener tube extends telescopically within the interior of the pipe end portion and the seal engages the interior of the pipe to seal the interior of the pipe to the interior of the stiffener tube. A rigid gripper positioned within the coupler shell engages the exterior surface of the pipe and prevents the pipe from being extracted from the coupler shell.

CROSS-REFERENCE TO RELATED APPLICATIONS 
This application is based on provisional application Ser. No. 60/007695 
entitled "PLASTIC PIPE COUPLER WITH INTERNAL SEALER", filed Nov. 29, 1995. 
CROSS-REFERENCE TO MICROFICHE APPENDIX 
This application is not related to any microfiche appendix. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention. The present invention relates to a stab-type 
coupler designed to couple a plastic pipe to a coupler fitting. In one 
embodiment, the coupler is configured to receive the end portion of a 
first plastic pipe and concentrically the end portion of a second plastic 
pipe so that the coupler functions to connect the two pipes together in an 
end-to-end relationship. In another embodiment, the coupler is in the form 
of a "L" fitting so that two lengths of pipe can be connected in an "L" 
connection. However, the pipe coupler may be employed as a portion of any 
other type of fitting wherein one end of a length of pipe is inserted into 
the coupler and is thereafter retained by the coupler, the coupler 
providing a sealed connection with the internal surface of the pipe. 
2. Description of Related Art. The present invention is generally referred 
to in the industry as a "stab-type" coupler, that is, the coupler of this 
disclosure is designed to be inserted manually onto the end of a length of 
plastic pipe. By mechanisms within the coupler, the extraction of the 
coupler thereafter from the end of the pipe cannot be accomplished without 
destroying either a portion of the coupler or a portion of the pipe. 
Further, the stab-type connector serves to form a sealed, leak proof 
communication with another fluid handling object, such as another length 
of pipe. 
In the past, stab-type connectors have concentrated upon obtaining a leak 
proof seal between a coupler and the exterior surface of a plastic pipe. 
In contrast, the present disclosure provides a means of obtaining a leak 
proof connection with the interior surface of a plastic pipe. In a more 
particular embodiment, the coupler of this disclosure has means for 
attaining leak proof contact with both the interior and exterior surface 
of a plastic pipe. 
Many of the basic elements of the plastic pipe coupler with internal sealer 
of this disclosure are illustrated and described in U.S. Pat. No. 
5,366,260 issued Nov. 22, 1994 and entitled "Plastic Pipe Coupler". The 
present disclosure is differentiated from the plastic pipe coupler in U.S. 
Pat. No. 5,366,260 primarily by the fact that the present disclosure 
teaches a method of attaining improved sealing effectiveness in an 
arrangement wherein sealing is accomplished on the interior of the plastic 
pipe being coupled and, in a preferred embodiment, simultaneously both on 
the interior and exterior surface of the plastic pipe being coupled. For 
additional background information as to plastic pipe couplers, reference 
may be had to the following previously issued United States patents: 
______________________________________ 
PATENT NO. 
INVENTOR TITLE 
______________________________________ 
Re. 33946 
Corzine Axially Split Clamp For Push-On 
Couplings 
4083583 Volgstadt et al 
Pipe Fitting Having A Non-Metallic 
Sealing Member 
4229025 Volgstadt et al 
Stab-Type Coupling 
4282175 Volgstadt et al 
Stab-Type Coupling and Method 
4407526 Cicenas Stab-Type Coupling and Method 
4628965 Passerell Stab-Type Coupling 
4632434 Proctor et al 
Coupling Means For Tubular Members 
4712813 Passerell et al 
Coupling Apparatus 
4991882 Gahwiler Fluid-Tight Connector 
5094494 McConnell Spring Lock Coupling 
5366260 Wartluft Plastic Pipe Coupler 
5378023 Olbrich Pipe Connection, Particularly On 
Composite Pipes 
5411297 Brown Conduit Mounting System 
______________________________________ 
SUMMARY OF THE INVENTION 
A coupler is provided for attachment to a plastic pipe of the type having 
substantially uniform internal and external surfaces. The coupling is 
formed of a hollow rigid coupling shell having opposed first and second 
ends. A passageway extends through the coupling shell. The passageway is 
defined by a larger internal diameter portion adjacent the first end and a 
smaller internal diameter portion adjacent the second end. An internal 
frusto-conical surface tapering towards the second end is provided on the 
interior surface of the hollow rigid coupling shell. 
A rigid stiffener tube that may be of metal or strong plastic is positioned 
within the coupling shell. The stiffener tube is of an external diameter 
slightly less than the internal diameter of the pipe to be secured to the 
coupler. Formed on the exterior surface of the stiffener tube adjacent an 
outer end thereof is an external circumferential groove. Positioned within 
the interior of the coupling shell is a rigid hollow gripper having a 
frusto-conical external surface that is in a slidable engagement with the 
coupler shell internal frusto-conical surface. The gripper is slidably 
received on the exterior surface of a pipe as the pipe is inserted into 
the coupler and has internal ridges thereon that bite into the external 
surface of a plastic pipe to thereby prevent, after insertion, the pipe 
from being extracted from the coupler. 
A toroidal elastomeric seal, such as an O-ring, is positioned within the 
circumferential groove on the stiffener tube. The elastomeric seal engages 
the internal surface of a pipe secured within the coupler to thereby seal 
the interior of the pipe to the interior of the stiffener tube. 
In one embodiment of the invention, two coupler shells are positioned 
end-to-end and secured within an exterior outer protective body, forming a 
coupling that will connect two lengths of pipe in concentric end-to-end 
relationship. In another embodiment, coupler shells are supported adjacent 
a coupler body and are contained within an outer protective body with the 
passageways through the coupler shell arranged perpendicular to each 
other. A fitting of this type provides an L-shaped connection for 
connecting two lengths of pipe at right angles to each other. The coupler 
of this invention can be formed as a portion of any other object wherein 
it is a desire to connect a length of plastic pipe to the object by means 
of a stab-type fitting that requires no tools for installation. 
An important feature of the invention is that plastic pipe is coupled in a 
stab fitting providing for sealing internally of the pipe. In a preferred 
arrangement, sealing is obtained internally and externally of the pipe. 
The exterior surface of plastic pipe can be easily damaged. That is, it 
can be scratched or abraded and such defects on the external surface can 
sometimes make it difficult to secure a leak proof seal with the external 
surface. The chance of damage to the interior surface of a plastic pipe is 
substantially less. Therefore, by sealing on the interior surface the 
effectiveness of stab-type connectors is substantially improved. In 
addition, by sealing both interiorly and exteriorly of a plastic pipe, the 
overall sealing effectiveness of a coupling is significantly enhanced. 
For a better understanding of the invention, reference should be had to the 
following description of the invention and the claims, taken in 
conjunction with the attached drawings.

DESCRIPTION OF THE INVENTION 
Referring now to the drawings and initially to FIGS. 1 through 4, there is 
illustrated a coupler 10 for use in securing together two lengths of 
plastic pipes 12A and 12B. A straight tubular stiffener 14 extends through 
the coupler. The stiffener is preferably constructed of rigid material, 
such as plastic or metal, and has ends 16A and 16B that are adjacent 
coupler ends 18A and 18B. 
Stiffener 14 has an external diameter slightly smaller than the internal 
diameter of pipes 12A and 12B in order to permit the pipes to be pushed 
onto the stiffener. As pipes 12A and 12B are pushed onto stiffener 14, 
they enter the coupler 10 via openings 20A and 20B provided respectively 
in the ends 18A and 18B. 
Stiffener 14 is secured within coupler 10 by means of a hub 22 that 
encircles the stiffener approximately midway between ends 16A and 16B. A 
knurled area 23 is formed on stiffener 14 intermediate ends 16A and 16B. 
Knurled area 23 helps maintain hub 22 in position on stiffener 14, or hub 
22 may be bonded to stiffener 14 at knurled area 23. 
Hub 22 is secured within coupler 10 between two hollow inner shell halves 
24A and 24B. Each of the shell halves 24A and 24B has an inner end 25 of 
enlarged internal diameter so that the inner ends 25 of shell halves 24A 
and 24B receive and secure the hub 22 between the shell halves 24A and 
24B. Positioned on both sides of an integral intermediate enlarged 
external diameter portion of hub 22 are O-rings 26A and 26B that seal hub 
22 to the interior of shell halves 24A and 24B. 
A protective outer body 27 surrounds shell halves 24A and 24B and serves to 
hold the shell halves in position around hub 22. Hub 22, inner shell 
halves 24A and 24B, and outer protective body 27 are all preferably 
constructed of rigid material, such as tough plastic. 
Referring now to FIG. 2, each of the shell halves 24A and 24B has an outer 
end 28 opposite inner end 25. Adjacent inner end 25, the hollow interior 
of each shell has an internal straight portion 30 with a uniform internal 
diameter. Opposed annular surfaces of hub 22 form innermost vertical walls 
31. Adjacent to the straight portion 30 each shell half 24A and 24B has an 
internal frusto-conical surface 32. Each frusto-conical surface 32 
progressively decreases in internal diameter in the direction away from 
straight portion 30 and towards outer ends 28 of each shell half 24A and 
24B. 
Adjacent to hub 22 and enclosed within the straight portions 30 of each 
shell half 24A and 24B is a toroidal follower 38. Adjacent follower 38 and 
enclosed within the straight portions 30 of each shell half is a toroidal 
front boot seal 40. Adjacent front boot seal 40 and enclosed within each 
of the straight portion 30 of each shell half is a hollow gripper 42. 
Each front boot seal 40 is preferably formed of a compressible material, 
such as rubber. As shown in FIG. 1, each follower 38 is provided with an 
inner side 44 that abuts hub 22 and an outer side 46 that meshes with the 
inner end 48 of front boot seal 40. 
A hollow interior surface 50 in the front boot seal 40 is provided with a 
plurality of sawtoothed-shaped flexible ridges or serrations 52 that flex 
to allow pipes 12A and 12B to be inserted into coupler 10. Once a pipe has 
been inserted into coupler 10 serrations 52 flex back against the pipe, 
forming multiple ring seals around the exterior of the pipe. Serrations 52 
are backwardly oriented so that they are forced into a tighter sealing 
engagement when pulling force is exerted on the pipe. In addition, when 
high internal fluid pressures are experienced, serrations 52 are forced 
into tighter sealing engagement with the pipe. 
Front boot seal 40 has an outer end that engages the forward face 56 of 
gripper 42. 
External surfaces 58 provided on each of the grippers 42 are generally 
frusto-conical to coincide in shape and slope with internal surface 32 of 
inner shell halves 24A and 24B. Grippers 42 are preferably constructed of 
rigid material, such as hard plastic. 
Similar to front boot seal 40, each of grippers 42 is provided with a 
hollow interior surface having a plurality of sawtooth-shaped ridges or 
gripper serrations 60. However, unlike the serrations 52 found on front 
boot seal 40, gripper serrations 60 are not flexible. 
Once pipes 12A and 12B have been fully inserted into coupler 10, pipes 12 
are held in place by backwardly oriented gripper serrations 60 which bite 
into the exterior surfaces of the pipes. Pulling force causes grippers 42 
to be pulled slightly outwardly, causing their exterior surfaces 58 to 
travel outwardly within the shell halves frusto-conical surfaces 32 
causing gripper serrations 66 to more tightly bite into the pipes. 
An important improvement of the coupler of this invention is a means of 
internally sealing plastic pipes 12A and 12B. Formed onto the exterior 
surface of stiffener 14 adjacent end 16A is a circumferential groove 62. 
In like manner, adjacent stiffener end 16B is a circumferential groove 64. 
Positioned in the grooves are O-rings 66A and 66B that sealably contact 
the internal surfaces 68A and 68B of plastic pipes 12A and 12B 
respectively. 
The previously known typical plastic pipe coupling of the mechanical type 
depends upon sealing engagement of elastomeric material with a pipe 
external surface. The external surface of plastic pipe is frequently 
marred by contact with physical objects during handling of the pipe, 
cutting of the pipe to length and fitting it in position. A scratch, dent, 
or the presence of dirt or other foreign material on the surface of a pipe 
can result in leakage when a mechanical coupling is employed. However, it 
has been observed that the interior surface of plastic pipe is less 
frequently damaged and therefore is more ideally suited to receive sealing 
contact with a sealed member. Therefore, the sealing arrangement as 
illustrated in FIGS. 1 through 4 is more likely to succeed in obtaining a 
leak proof seal. 
FIG. 3 and 4 show cross-sectional views of the coupler of FIGS. 1 and 2. 
FIG. 5 shows an alternate embodiment of the invention wherein the coupling 
is in the form of an "L" and where like numbered components have like 
functions as described with reference to FIGS. 1 through 4. The main 
structure or body 72 has a fluid passageway 74 therethrough. 
Positioned at the ends of body 72 are shells 76A and 76B that correspond 
and function like shell 24A and 24B of FIGS. 1 through 4. Retained within 
shells 76A and 76B are followers 38, front boot seals 40 and grippers 42 
all have the function as previously described. 
Outer protective body 78 is molded of stiff plastic around the assembled 
internal components. 
Extending from a first end of body 72 is a first stiffener 80A and from the 
second end of body 72 is a second stiffener 80B. Near the inner end of 
each of the stiffeners is a groove 82 that receives an O-ring 84. Each of 
the stiffeners includes a knurled portion 86 to assist in retaining the 
stiffeners in connection with coupler body 72 or the knurled portions may 
assist in bonding the stiffeners to the body. 
Each stiffener has, adjacent its outer end, a circumferential exterior 
groove 88, each of the grooves receiving an O-ring 90. Positioned within 
one end of the L-shaped coupling is a first plastic pipe 12A and in the 
other end of the coupling a second plastic pipe 12B. Plastic pipes 12A and 
12B are retained within the coupling by grippers 42, as previously 
described, with external sealing provided by followers 38 and front boot 
seals 40 as has been described with reference to FIGS. 1 through 4. An 
important feature of the L-shaped fitting of FIG. 5 is the provision of 
O-rings 90 on stiffeners 80A and 80B that seal the stiffeners to the 
interior of pipes 12A and 12B. As previously stated, sealing by engagement 
of O-rings with the internal surfaces of pipes has increased effectiveness 
since the internal surfaces are less likely to be scratched or otherwise 
marred in handling of the pipes. 
Positioned about a first end of body 72 is an O-ring 92A and in like 
manner, positioned about the opposite end of body 72 is an O-ring 92B. 
O-rings 92A and 92B help maintain a leak proof relationship between body 
72 and shells 76A and 76B. 
The claims and the specification describe the invention presented and the 
terms that are employed in the claims draw their meaning from the use of 
such terms in the specification. The same terms employed in the prior art 
may be broader in meaning than specifically employed herein. Whenever 
there is a question between the broader definition of such terms used in 
the prior art and the more specific use of the terms herein, the more 
specific meaning is meant. 
While the invention has been described with a certain degree of 
particularity, it is manifest that many changes may be made in the details 
of construction and the arrangement of components without departing from 
the spirit and scope of this disclosure. It is understood that the 
invention is not limited to the embodiments set forth herein for purposes 
of exemplification, but is to be limited only by the scope of the attached 
claim or claims, including the full range of equivalency to which each 
element thereof is entitled.