Note: Descriptions are shown in the official language in which they were submitted.
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RESILIENT PIPE GASKET
FIELD OF THE INVENTION
This invention relates to gaskets for forming at least
soil-tight joints between pipes or pipe fittings.
BACKGROUND OF THE INVENTION
Pipes having outer corrugated surfaces are known for use
as drain and sewer pipes to be buried in soil. To provide at
least a soil-tight seal, and preferably a water-tight seal,
between two lengths of pipe, a gasket is provided extending
circumferentially around the outer surface of a first pipe
which is to be inserted into the bell of a second pipe.
However, the disadvantage exists that prior art gaskets
on an outer surface of a corrugated pipe are easily displaced
during insertion of the first pipe into the bell of the second
pipe. This results in poorly sealed joints between pipes.
An additional disadvantage exists that gaskets for drain
and sewer pipes are typically fitted in the valleys between
corrugation ribs and require relatively large volumes of
gasket material. Thus, it is difficult to obtain sufficient
compression because of the relative flexibility of the bell
of the second pipe. This makes the gasket less likely to
resist "blowout" forces during times of unusually large water
flow through the pipes. High water flow results in pressure
increases which cause displacement of the gasket from its
preferred position between the two pipes, again resulting in
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a poorly sealed joint between pipes.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to
at least partially overcome the disadvantages of the prior art
discussed above.
Therefore, it is one object of the present invention to
provide a resilient pipe gasket for sealing joints between
corrugated pipes.
It is another object of the present invention to provide
a resilient pipe gasket for corrugated pipes which will not
become displaced during joining of two pipes.
It is yet another object of the present invention to
provide a resilient pipe gasket. which will not become blown
out from a joint between two pipes during periods of
relatively higher water pressure in the pipes.
Accordingly, in one of its broad aspects, the present
invention provides A resilient pipe gasket comprising: (aj a
base adapted to be received on an outer surface of a first
2D pipe; wherein the outer surface of the first pipe has at least
one circumferentially extending rib adjacent to an end
thereof, and the first pipe is adapted to mate with a second
pipe with the end of the first pipe being received in an end
of the second pipe; and wherein the base has an inner surface
adapted to be seated on one of the ribs; (b) sealing means
provided on an outer surface of the base, the sealing means
being adapted to sealingly engage a first inner surface of the
second pipe; (c) a forward leg extending inwardly from the
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base and adapted to extend along a forward side of the rib,
the forward side of the rib facing the end of the first
pipe; and (d) a flap extending outwardly and forwardly from
an inner portion of the forward leg toward the end of the
first pipe, the flap having an engaging surface at an outer
portion f the flap adapted to engage a second inner surface
of the second pipe during rotation in a rearward direction
of the gasket about the rib.
In another one of its broad aspects, the present
invention provides a resilient, annular pipe gasket for
forming a seal between an annular rib provided on a
radially outer surface of a first pipe and a radially inner
surface of a second pipe, the rib having a radially outer
surface, an axially forward side facing the end of the
first pipe and an opposite axially rearward side, the first
pipe and the second pipe being adapted to mate with a
portion of the first pipe having the annular rib being
received in the second pipe, the pipe gasket comprising:
(a) a sealing base having a radially inner surface
and a radially outer surface provided with sealing means;
(b) a forward leg extending radially inwardly from an
axially forward portion of the base; and
(c) a flap extending radially outwardly and axially
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forwardly from a radially inner portion of the forward leg,
the flap having a pipe engaging surface at a radially outer
portion of the flap,
wherein a first radial distance between the radially
inner surface of the base and a radially outermost portion
of the sealing means is greater than a second radial
distance between the radially inner surface of the base and
the pipe engaging surface of the flap, and wherein the
first radial distance is less than a third radial distance
between the radially inner portion of the forward leg and
the pipe engaging surface.
In yet another one of its broad aspects, the present
invention provides a pipe connection, comprising:
an end portion of a first pipe having a radially outer
surface provided with an annular rib, the rib having a
radially outer surface, an axially forward side facing the
end of the first pipe and an opposite axially rearward
side;
an end portion of a second pipe in which the end
portion of the first pipe is received; and
a resilient, annular pipe gasket comprising:
(a) a base forming a seal between the radially outer
surface of the rib of the first pipe and a first radially
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inner surface of the second pipe, the base having a
radially inner surface seated on the radially outer surface
of the rib, and a radially outer surface seated on the
radially outer surface of the rib, and a radially outer
surface provided with sealing means which sealingly engage
the first radially inner surface of the second pipe;
(b) a forward leg extending radially inwardly from
the base along the axially forward side of the rib; and
(c) a flap extending radially outwardly from a
radially inner portion of the forward leg and axially
forwardly toward the end of the first pipe, the flap having
an engaging surface at a radially outer portion of the
flap, the engaging surface engaging a second radially inner
surface of the second pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages of the present
invention will become apparent from the following
description, taken together with the accompanying drawings,
in which:
Figure 1 is a cross-section view of a gasket according
to the present invention receiving on a first pipe, prior
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to insertion of the first pipe into the bell of a second
pipe;
Figure 2 is a close-up of the cross-sectional view
shown in Figure 1;
Figure 3 is a close-up of the gasket of Figure 2 when
the first pipe is partially inserted into the second pipe;
and
Figure 4 is a close-up of the gasket of Figure 2 when
the first pipe is completely inserted into the second pipe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention are now
described with reference to Figures 1 to 4.
Figure 1 is a cross-section view in the longitudinal
direction illustrating an end of a first pipe 10 having two
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layers, an inner layer 12 having a smooth inner surface 14 and
an outer corrugated layer 16 having a plurality of
circumferential, outwardly extending ribs 18. In a typical
application of the present invention, first pipe l0 is a drain
or sewer pipe to be buried in soil, for example along a
highway.
The layers 12 and 16 of first pipe 10 are relatively thin
and are preferably made of a plastic material such as
polyethylene. The provision of ribs 18 in corrugated layer 16
increases the rigidity of first pipe 10.
The first pipe 10 is adapted to mate with second pipe 20.
The end of first pipe 10 shown in Figure 1 is adapted to be
received in the end of a second pipe 20. As shown in
Figure 1, second pipe 20 has an enlarged bell 22 with a smooth
inner surface 24 into which the end of first pipe 10 is
inserted. Second pipe 20 is typically of the same or similar
construction as first pipe 10, comprising inner layer 26
having a smooth inner surface 28, and outer corrugated
layer 30 having circumferential, outwardly extending ribs 32.
As may be appreciated, pipes 10 and 20 are more typically
of identical construction. That is, the end of first pipe 10
opposite to that shown in Figure 1 typically has a bell
identical to bell 22 of second pipe 20. Similarly, the end
of second pipe 20 opposite to that shown in Figure 1 is
typically identical to the end of first pipe 10 shown in
Figure 1. Furthermore, although the drawings show two
pipes 10 and 20 being joined, it is to be appreciated that one
or both of pipes 10 and 20 could be replaced by a fitting such
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as an elbow or a "T". Therefore, it must be understood that
"pipe" as used herein includes fittings such as, for example,
couplings, elbows, "T"'s, "Y"'s and adaptors.
Typically, pipes such as pipes 10 and 20 are produced in
various sizes. one common size is pipes l0 and 20 with an
inside diameter of about 30 inches. The following description
will be given with reference to this size~of pipe. However,
it must be remembered that this description is merely an
example and applies to other sizes of pipe with suitable
variations. Typically, the clearance between the top of a
rib 18 and the inner surface 24 of the bell 22 is from about
0.2 inches to about 0.6 inches, with an average clearance of
about 0.4 inches.
For convenience, the rib 18 closest to the end of first
pipe l0 shown in Figure 1 is labelled 18a. However, it is to
be appreciated that rib 18a is typically identical to the
other ribs 18 of first pipe 10.
Ribs i8 are shown in Figure 1 as having a truncated,
conical cross section, with a flat, horizontal outer
surface 34, a forwardly-sloped face 36 and a rearwardly-sloped
face 38. Although ribs 18 are shown in Figure 1 as having a
truncated conical shape, it is to be appreciated that ribs 18
may be of other preferred shapes. For example, the ribs may
be rounded or more rectangular.
As shown in Figure 1, seated on endmost rib 18a of
pipe 10 is a preferred gasket 40 according to the present
invention. An enlarged, longitudinal cross-sectional view of
the gasket of Figure 1 is shown in Figure 2.
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The inventors have appreciated that it is preferred to
position gasket 40 on top of a rib 18 because that location
is the most rigid point on the outer surface of pipe 10.
Positioning gasket 40 on the most rigid point of pipe to
reduces the amount of bending of pipe 10 caused by compression
of gasket 40.
Although gasket 40 is shown in Figure 1 as being received
on top of endmost rib 18a of pipe 10, if is to be appreciated
that this may not necessarily be the case. Gasket 40 may be
received on any rib 18 which will be received inside bell 22
when pipes 10 and 20 are joined.
Gasket 40 has a base 42 which is shaped to be seated on
rib 18a. This helps to prevent displacement of gasket 40 from
the top of rib 18 prior to installation and joining of the
pipes, as well as preventing displacement of gasket 40 from
the top of rib 18 during and after installation.
In the embodiment of the invention illustrated in
Figure 1, base 42 has an inner surface 44 which is flat and
is adapted to be received on top of rib 18a having flat outer
surface 34.
The gasket 40 preferably comprises a rearward leg 46
extending inwardly along the rearwardly-sloped face 38 of
rib 18a, and a forward leg 48 extending inwardly along the
forwardly-sloped face 36 of rib 18a.
Although gasket 40 is shown in the drawings as having a
rearward leg 46, it is to be appreciated that gaskets
according to the present invention may be provided which do
not have a rearward leg such as leg 46. The primary function
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of rearward leg 46 is to prevent displacement of, gasket 40
from the top of rib 18a prior to installation, for example by
handling of the pipe 10 during loading and unloading from
transportation vehicles.
The base 42 of gasket 40 has an outer surface 50 on which
is provided sealing means 52 adapted to engage the inner
surface 24 of bell 22 as pipe 10 is inserted into bell 22.
Therefore, the sealing means 52 preferably extends outwardly
(in the radial direction) from the outer surface 50 of base 42
a sufficient distance to engage inner surface 24 of bell 22
as pipe 10 is inserted inside pipe 20.
In the preferred embodiment of gasket 40 shown in
Figure 1, the sealing means 52 comprises two resilient
arms 54, 56 spaced from one another and extending outwardly
from the outer surface 50 of base 42. Preferably, as shown
in Figure 1, both the forward arm 54 and the rearward arm 56
are directed rearwardly (in the longitudinal direction) away
from the bell 22 of second pipe 20. Preferably, rearward
arm 56 extends outwardly from the base 42 further than the
forward arm 54.
Most preferably, the thickness of base 42 Prom inner
surface 44 to outer surface 50 is less than the clearance
between outer surface 34 of rib 18a of first pipe 10 and the
inner surface 24 of bell 22 of second pipe 20.
In a particularly preferred embodiment of the present
invention for application to pipes having about 30 inch
diameters, the thickness of base 42 of gasket 40, measured
from inner surface 44 to outer surface 50, is from about 0.25
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inches to about 0.35 inches.
Preferably, the radial distance or height of resilient
arms 54 and 56, measured as the distance from the inner
surface 44 of gasket 40 to the outermost portions of resilient
arms 54 and 56, is such that arms 54 and 56 will be in a
compressed state after pipe l0 is inserted into pipe 20.
Therefore, the total radial distance or height of resilient
arms 54 and 56 together with the thickness of base 42 is
greater than the clearance between the outer surface 34 of
rib 18 and the inner surface 24 of bell 22.
The resilient arms 54, 56 are adapted to sealingly engage
the inner surface of pipe 20. Sometimes only a soil-tight
seal is required between pipes 10 and 20, and sometimes a
water-tight seal is required. For example, in highway
drainage systems, it is not usually necessary to have a water-
tight seal between pipes, which are typically buried in soil.
However, soil must be prevented from entering the pipes.
Although Figure 1 illustrates sealing means 52 comprising
two resilient arms 54 and 56, it is to be appreciated that
sealing means of numerous other shapes and configurations may
be used. For example, the sealing means may be in the form
oP rectangular or rounded projections extending from the outer
surface 50 of base 42. Alternatively, the sealing means may
comprise one resilient arm similar to arm 54 or 56, or may
comprise more than two such arms or projections.
Gasket 40 shown in Figure 1 further comprises a flap 58
extending outwardly (in the radial direction) and forwardly
from an inner (in the radial direction) portion 60 of forward
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leg 48. The operation of flap 58 is now described with
reference to Figures 3 and 4, illustrating the insertion of
first pipe 10 into second pipe 20.
In Figure 3, pipe 10 is being inserted in a forward
direction into bell 22 of pipe 20. The forward direction is
shown by arrow A. Of course, the actual movement is relative
in that pipe 20 could be moved in the rearward direction or
both pipes 10 and 2o could be moved towards each other.
As shown in Figure 3, once arms 54 and 56 make contact
with inner surface 24 of bell 22, they are bent rearwardly and
compressed inwardly.' Further forward advancement of pipe to
relative to pipe 20 will be resisted by the friction on the
inner surface 24 of bell 22 by arms 54 and 56. As may be
appreciated, this frictional resistance to forward movement
of pipe 10 into pipe 20 is increased with increasing
compression in the radial direction of the gasket 40.
This frictional contact between resilient arms 54 and 56
on inner surface 24 of bell 22 results in a rearwardly
directed force being exerted on gasket 40. This rearward
force causes gasket 40 to be pushed in a rearward direction
relative to pipe 10. Because the base 42 of gasket 40 is
seated on rib 18a, this rearward force on gasket 40 is
transferred into rotational displacement of the gasket 40
relative to and about rib 18a, in the direction indicated by
arrow B in Figures 3 and 4.
Figure 4 illustrates (with exaggeration) the position of
gasket 4o after some rotational displacement of gasket 40 has
taken place. Specifically, base 42 of gasket 40 is pushed
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rearwardly over outer surface 34 of rib 18. This causes
rearward leg 46 of gasket 40 to be pushed inwardly radially
over the rearwardly-sloped face 38 of rib 18a, and also causes
forward leg 48 to advance outwardly radially along the
forwardly-sloped face 36 of rib 18a.
As a result of this rearward rotational movement of
gasket 40, an outer engaging surface 62 of flap 58 is brought
into engagement with the inner surface 24 of bell 22. The
engaging surface 62 of flap 58 is shown in Figure 4 as the
rearward surface of the outermost (in the radial direction)
tip of flap 58.
Flap 58 extends radially outwardly a sufficient distance
such that engaging surface 62 engages inner surface 24 of
bell 22 during rotation of gasket 40 about rib 18a.
Preferably, engaging surface 62 does not extend radially
outwardly so far as to be moved rearwardly during joining of
pipes 10 and 20. Therefore, the radial distance between the
inner surface 44 of base 42 and the engaging surface 62 of
flap 58 is less than the clearance between the outer
surface 34 of rib 18a and the inner surface 24 of bell 22.
Furthermore, the resilient arms 54 and 56 of sealing means 52
extend radially outwardly further than the engaging surface 62
of flap 58. Most preferably, flap 58 does not extend
radially outwardly past the inner surface 44 of gasket 40,
such that engaging surface 62 is located radially inward of,
or at the same radial distance as, inner surface 44 of
gasket 40.
It is to be appreciated that, as the clearance between
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the outer surface 34 of ribs 18 and the inner surface 24 of
bell 22 approaches the radial distance or height of the
resilient arms 54 and 56, the degree of compression of
resilient arms 54 and 56 is relatively small and may result
in little or no rotation of gasket 40 relative to rib 18a.
In this situation, pipe 10 may be completely inserted into
bell 22 without flap 58 contacting or engaging the inner
surface 24 of bell 22.
As shown in the drawings, the forward leg 48 and the
flap 58 of gasket 40 together define a V-shaped member 64.
The V-shaped member 64 helps to prevent rotational
displacement of gasket 40 relative to rib 18a, whether caused
by friction during joining of pipes 10 and 20, or caused by
fluid pressure within pipes 10 and 20 after they are joined.
Although the precise reasons why gasket 40 is able to
carry out this function are not fully understood, the
following is the current understanding.
Figure 4 shows gasket 40 as having been rotated
rearwardly relative to rib 18a, either by frictional forces
during installation as discussed above or by fluid pressure
within pipes 10 and 20 after installation. In the orientation
of gasket 40 shown in Figure 4, both sealing means 52 and
engaging surface 62 are in frictional engagement with inner
surface 24 of bell 22.
Rearwardly directed forces applied to gasket 40 may cause
V-shaped member 64 to open such that a distance between the
engaging surface 62 of flap 58 and the base 42 of gasket 40
increases. However, V-shaped member 64 has sufficient
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rigidity that it resists being opened to such a degree that
it may be forced through the opening between the rib 18a and
the inner surface 24 of bell 22.
As discussed above, V-shaped member 64 may be caused to
open by rearwardly directed forces acting on gasket 40, for
example frictional forces caused by joining of pipes 10
and 20, or possibly rearward forces caused by fluid pressure
within pipes 10 and 20 after installation. However, V-shaped
member 64 may also be caused to open by radially outwardly
1o directed forces caused by fluid pressure within pipes 10
and 20 after installation of pipes 10 and 20.
There may be some small amount of further rearward
displacement of gasket 40 due to opening of V-shaped
member 64. However, this further rearward rotation of
gasket 40 will not result in displacement of gasket 40 from
the top of rib 18a. Therefore, V-shaped member 64 prevents
gasket 40 from becoming displaced from rib 18a during joining
of pipes 10 and 20 and also prevents gasket 4o from becoming
displaced, or "blown out", from between pipes l0 and 20 by
relatively high water pressures.
Another mechanism exists which may contribute to the
resistance of rearward displacement of gasket 40. Since
flap 58 is positioned forwardly of rib 18a, it may preferably
bias forward leg 48 rearwardly against forwardly-sloped
face 36 of rib 18a in response to a rearwardly directed force
exerted on gasket 40. This rearwardly directed force may be
caused either by insertion of pipe 10 into pipe 20, or by
water pressure within pipes l0 and 20 after installation.
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This biasing of forward leg 48 against forwardly-sloped
face 36 of rib 18a is believed to contribute to preventing
substantial rearward displacement of the base 42 of gasket 40
relative to rib 18a after engagement of engaging surface 62
of flap 58 with inner surface 24 of bell 20.
Although not necessary, flap 58 preferably serves the
additional function that the additional contact provided by
engagement of engaging surface 62 with inner surface 24 of
bell 22 provides an additional seal, and preferably a water-
tight seal, between pipe 10 and pipe 20.
Preferably, the angle B of flap 58 relative to a vertical
plane, as shown in Figure 1, is from about 20° to about 60°.
However, it is to be appreciated that the flap may be at any
angle so long as the engaging surface 62 of flap 58 makes
contact with the inner surface 24 of bell 22 to prevent
rotation of gasket 40 relative to rib 18.
Gasket 40 may preferably be unitarily formed, for example
by extrusion and splicing, or by molding. However, it may
also be preferred to provide a gasket 40 comprising materials
of different rigidity. For example, the sealing means 52 is
preferably relatively compressible to form a seal with the
inner surface 24 of bell 22 without causing the bell 22 to
bulge. On the other hand, it is desirable that the V-shaped
member 64 is made of a more rigid material which is more
difficult to stretch and compress, so that the flap 58
prevents rearward rotation of the gasket.
When gasket 40 is unitarily formed from a single
material, the V-shaped member 64 comprising flap 58 and
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forward leg 48 is preferably thicker than the rearward leg 46.
For example, in one preferred embodiment for a gasket 40 for
a 30-inch diameter pipe, V-shaped member 64 has a thickness
of from about 0.20 to about 0.25 inches, whereas rearward leg
has a thickness of about 0.16 inches.
Preferably, the gasket is made of rubber or an
elastomeric material including thermoplastic elastomers
(TPE's), thermoplastic rubber, flexible polyvinyl chloride and
thermosetting elastomers.
l0 Although the invention has been described in connection
with certain preferred embodiments, it is not intended to be
limited thereto. Rather, it is intended that the invention
cover all alternative embodiments as may be within the scope
of the following claims.
It will be understood that, although various features of
the invention have been described with respect to one or
another of the embodiments of the invention, the various
features and embodiments of the invention may be combined or
used in conjunction with other features and embodiments of the
invention as described and illustrated herein.
Although this disclosure has described and illustrated
certain preferred embodiments of the invention, it is to be
understood that the invention is not restricted to these
particular embodiments. Rather, the invention includes all
embodiments which are functional or mechanical equivalents of
the specific embodiments and features that have been described
and illustrated herein.
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