U.S. patent application number 10/231663 was filed with the patent office on 2004-03-04 for coupling device for polymeric pipes.
Invention is credited to Chelchowski, David, Puckett, Geoffrey.
Application Number | 20040041399 10/231663 |
Document ID | / |
Family ID | 31887670 |
Filed Date | 2004-03-04 |
United States Patent
Application |
20040041399 |
Kind Code |
A1 |
Chelchowski, David ; et
al. |
March 4, 2004 |
COUPLING DEVICE FOR POLYMERIC PIPES
Abstract
The present invention relates to a pipe coupling of the type
where a pipe is freely insertable into the coupling and where a nut
causes engagement of a grip ring and gasket with the pipe to
provide a seal between the coupling and the pipe, and where within
the coupling there is disposed a stop to indicate to a user
inserting the pipe freely that the pipe has been inserted to its
required location. The stop is located at a position where there is
room beyond the stop for the pipe to move into. Tightening of the
nut causes the pipe to move further into the coupling beyond the
stop. This solves the problem of the pipe being inserted too deeply
into the coupling and being deformed when the nut is tightened
further.
Inventors: |
Chelchowski, David; (Largs
Bay, AU) ; Puckett, Geoffrey; (Hallet Cove,
AU) |
Correspondence
Address: |
Ralph C. Francis
Francis Law Group
1808 Santa Clara Avenue
Alameda
CA
94501
US
|
Family ID: |
31887670 |
Appl. No.: |
10/231663 |
Filed: |
August 29, 2002 |
Current U.S.
Class: |
285/343 |
Current CPC
Class: |
F16L 19/075 20130101;
F16L 19/086 20130101; F16L 47/04 20130101 |
Class at
Publication: |
285/343 |
International
Class: |
F16L 017/00 |
Claims
1. A pipe coupling including: a body having an external thread and
annular inner surfaces defining a socket within the body of larger
outer diameter at an outer end than at an intermediate location of
said socket; a stop extending at least partially around the annular
inner surface in the intermediate location of said socket at a
position offset from the end of said intermediate location where
the end is distal from said outer end; a nut having an internal
thread at an inner end thereof engaging said body external thread,
an inwardly facing abutment surface between ends of said nut, and
an outwardly converging internal circular surface between said
abutment surface and an outer end of said nut; an annular sleeve
having an abutment surface at is outer end co-operable with said
nut abutment surface, and a resilient gasket secured to its inner
end; a deformable gripping member having an outwardly converging
outer surface complementary to said outwardly converging internal
nut surface, the gripping member having an internal surface with
barbs extending radially inwardly therefrom; internal diameters of
said socket inner end, sleeve and gripping member all being
slightly greater than an external diameter of a pipe to which said
coupling is securable, such that an end of said pipe is freely
insertable through said gripping member and into said socket
intermediate part until it abuts the stop, and tightening of said
nut over said external thread causes axial movement of said gasket
ring, sealable engagement of said gasket ring and said body,
radially inward deformation of said gripping member such that the
said barbs clamp said pipe, and axial movement of said pipe over
the stop and towards the end of said intermediate location.
2. A pipe coupling as in claim 1 wherein the stop is an annular
abutment surface extending circumferentially around the annular
inner surface.
3. A pipe coupling as in claim 1 wherein the stop is a plurality of
projections positioned circumferentially and symmetrically around
the inner annular surface.
4. A pipe coupling as in claim 3 where there are at least three
projections disposed 120 degrees angularly to each other.
5. A pipe coupling as in claim 3 or 4 wherein the projections are
wedge shaped projections whose longitudinal direction extends in
the longitudinal direction of the coupling.
6. A pipe coupling as in claim 5 wherein the front surface of the
wedge facing the outer end is disposed at an angle other than a
right angle but greater than 45 degrees to the longitudinal
axis.
7. A pipe coupling as in claim 6 wherein the front surface has at
least two faces whose angle to the longitudinal axis is less than
90 degrees.
8. A pipe coupling as in claim 3 or 4 wherein the projections are
wedge shaped projections whose longitudinal direction extends
generally perpendicular to the longitudinal direction of the
coupling.
9. A pipe coupling as in claim 8 wherein the wedge shaped
projections are of an arcuate shape.
10. A pipe coupling of the type where a pipe is freely insertable
into the coupling and including: a body having annular inner
surfaces and external threads; a nut having internal threads
adapted to engage said body; a grip ring disposed within the body
and of a shape and configuration that rotation of the nut causes it
to move in both the axial and longitudinal direction, said nut
having projections adapted to engage said pipe when the nut is
tightened and having an end adapted to engage a gasket and move it
into a sealing cavity when the nut is tightened, wherein said body
includes an abutment surface located at a position away form the
ends of said body to provide a guide to the user when inserting the
pipe freely into the coupling and where the abutment surface is of
a shape and configuration such that under rotation of the nut the
pipe is caused to move over said abutment surface and further into
said coupling.
Description
[0001] Coupling for engagement of polymeric pipes where the pipe is
inserted into a coupling to a first position and where tightening
of the coupling causes the pipe to be drawn further into said
coupling.
[0002] In particular this invention relates to a coupling that is
suitable for engaging the outer surface of a polymeric pipe and
where a pipe is inserted into an already assembled coupling.
Provided in the coupling is a first stop indicating to a user that
a pipe has been sufficiently inserted into the pipe, there
remaining sufficient space to accommodate further movement of the
pipe under tightening of the coupling nut.
BACKGROUND OF THE INVENTION
[0003] Polymeric pipe couplings are well known and typically
include a body, nut, and grip ring. A pipe is inserted into the
body. Tightening of the nut compresses the grip ring that in turn
engages the pipe. Further tightening of the nut causes urging of
the pipe further into the body. A typical coupling was described
and illustrated in our U.S. Pat. No. 5,593,186 entitled "Coupling
for Outer Surface Engagement of Polymeric Pipe". The described
coupling is adapted for engagement with the outer surface of a
polymeric pipe. The coupling includes a sub-assembly of a
compression sleeve, a resilient gasket ring permanently attached to
the inner end of the compression sleeve, a gripping member, and a
nut. The gasket ring encounters an abutment in a socket in the body
as the nut is tightened, and further tightening of the nut radially
compresses the gripping member so that its inwardly directed barbed
projections engage the outer surface of a pipe to which the
coupling is attached. The end of the pipe is freely insertable
through the gripping member and sleeve and into the socket in the
body. There are also provided abutment surfaces within the body
coupling and the nut that abut inner and outer surfaces of a flange
outstanding from the outer end of the compression sleeve. Also
disclosed is an embodiment with a transition spigot having a barbed
tail inserted into an end of a pipe enabling the coupling to
accommodate a range of similar but different diameter pipes.
[0004] The coupling described in the aforesaid specification and
other earlier couplings have proven to be very successful, both
technically and commercially. Failure is almost unknown and in some
areas of the world fittings made in accordance with that
specification have achieved great success.
[0005] A practical problem which is frequently encountered with
couplings made in accordance with said patent U.S. Pat. No.
5,593,186 (and other fittings having in common a gripping member
and a tightening nut), is that when the nut has been partially
tightened it radially compresses the gripping member causing the
inwardly directed barbed projections to engage the outer surface of
a pipe to which the coupling is attached. Further tightening of the
nut then results in the pipe being urged in the direction of the
nut travel along its longitudinal axis due to the force exerted on
the pipe by the barbed projections. But, because the pipe is
typically inserted into the coupling until its end abuts against an
abutment surface, there is no additional room for the pipe to move
into. As the nut is further tightened, the pipe is subject to
significant forces that result in its deformation and leads to
changes in the flow of the fluid through the pipe. Further, the
rotation of the nut requires more and more torque to effect the
appropriate compression on the seal, and at times, it may be
incorrectly assumed that the nut is fully tightened due to the
resistive forces of pipe leading to couplings that leak.
[0006] It is therefore an object of the present invention to
provide for a coupling whereby when the pipe is inserted into the
coupling it is caused to be held at a first location, and whereby
when the coupling nut is further tightened the pipe is caused to be
drawn further towards a second location.
[0007] It is a further object of the present invention to provide
for a coupling that allows manual insertion of the pipe and that
prevents the pipe from being inserted too far into the
coupling.
[0008] There is currently no known prior art to the applicant
whereby a pipe is caused to abut a coupling at a first location and
whereby further tightening of the coupling nut will cause the pipe
to be drawn towards a second location.
BRIEF SUMMARY OF THE INVENTION
[0009] Therefore in one form of the invention there is proposed a
pipe coupling including:
[0010] a body having an external thread and annular inner surfaces
defining a socket within the body of larger outer diameter at an
outer end than at an intermediate location of said socket;
[0011] a stop extending at least partially around the annular inner
surface in the intermediate location of said socket at a position
offset from the end of said intermediate location where the end is
distal from said outer end;
[0012] a nut having an internal thread at an inner end thereof
engaging said body external thread, an inwardly facing abutment
surface between ends of said nut, and an outwardly converging
internal circular surface between said abutment surface and an
outer end of said nut;
[0013] an annular sleeve having an abutment surface at is outer end
co-operable with said nut abutment surface, and a resilient gasket
secured to its inner end;
[0014] a deformable gripping member having an outwardly converging
outer surface complementary to said outwardly converging internal
nut surface, the gripping member having an internal surface with
barbs extending radially inwardly therefrom;
[0015] internal diameters of said socket inner end, sleeve and
gripping member all being slightly greater than an external
diameter of a pipe to which said coupling is securable, such that
an end of said pipe is freely insertable through said gripping
member and into said socket intermediate part until it abuts the
stop, and tightening of said nut over said external thread causes
axial movement of said gasket ring, sealable engagement of said
gasket ring and said body, radially inward deformation of said
gripping member such that the said barbs clamp said pipe, and axial
movement of said pipe over the stop and towards the end of said
intermediate location.
[0016] The use of the stop assists in properly coupling the pipe. A
user inserts the pipe into the coupling to a location where they
can feel resistance to the pipe moving further into the coupling.
This position then still provides the pipe with room to move
inwardly into the pipe as it does when the nut is tightened. In
this way, since the pipe is not inserted too deeply into the
coupling its end is not caused to deform under tightening of the
nut.
[0017] Preferably the stop is an annular abutment surface extending
circumferentially around the annular inner surface.
[0018] Preferably the stop is a plurality of projections positioned
circumferentially and symmetrically around the inner annular
surface.
[0019] In preference there are at least three projections disposed
120 degrees angularly to each other. Preferably the height of the
projections is at least equal to the thickness of the pipe.
[0020] In preference the projections are wedge shaped projections
whose longitudinal direction extends in the longitudinal direction
of the coupling.
[0021] Preferably the front surface of the wedge facing the outer
end is disposed at an angle other than a right angle but greater
than 45 degrees to the longitudinal axis.
[0022] Preferably the front surface has at least two faces whose
angle to the longitudinal axis is less than 90 degrees.
[0023] Advantageously the projections are wedge shaped projections
whose longitudinal direction extends generally perpendicular to the
longitudinal direction of the coupling.
[0024] Advantageously the wedge shaped projections are of an
arcuate shape.
[0025] In a further form of the invention there is proposed a pipe
coupling of the type where a pipe is freely insertable into the
coupling and including:
[0026] a body having annular inner surfaces and external
threads;
[0027] a nut having internal threads adapted to engage said
body;
[0028] a grip ring disposed within the body and of a shape and
configuration that rotation of the nut causes it to move in both
the axial and longitudinal direction, said nut having projections
adapted to engage said pipe when the nut is tightened and having an
end adapted to engage a gasket and move it into a sealing cavity
when the nut is tightened, wherein said body includes an abutment
surface located at a position away form the ends of said body to
provide a guide to the user when inserting the pipe freely into the
coupling and where the abutment surface is of a shape and
configuration such that under rotation of the nut the pipe is
caused to move over said abutment surface and further into said
coupling.
[0029] Thus the present invention provides for an improved pipe
coupling where there is a mechanism to indicate to a user that a
pipe as been sufficiently inserted into the coupling whilst there
still remaining room for the pipe to move axially inwardly into the
coupling as it does under the forcing of the grip ring.
[0030] The typical coupling to which the present invention can be
applied includes a gripping member and a sub-assembly of a
compression sleeve and resilient gasket ring generally attached to
the inner end of the compression sleeve. A pipe end is freely
insertable through the sub-assembly and into a socket in the body
of the coupling abutting against a pipe abutment surface or stop.
The gasket ring encounters an abutment in its socket in the body as
the nut is tightened, wherein tightening of the nut radially
compresses the gripping member so that its inwardly directed barbed
projections engage the outer surface of a pipe to which the
coupling is attached. When the barbs have engaged the pipe, further
tightening of the nut causes the pipe to be forced inwardly into
the coupling past the pipe abutment surface and towards an abutment
shoulder. The longitudinal distance between the pipe abutment
surface and the abutment shoulder is generally equal to or greater
than the longitudinal travel of the nut from the position at which
the barbed projections have gripped the pipe to the final tightened
position of the nut. There are also provided abutment surfaces
within the body of the coupling or the end of the body, and the
nut, that abut inner and outer surfaces of a flange outstanding
from the outer end of the compression sleeve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate several
implementations of the invention and, together with the
description, serve to explain the advantages and principles of the
invention. In the drawings,
[0032] FIG. 1 is a central elevational section that shows a pipe
end inserted through a subassembly comprising a nut, gripping
member and sleeve, and into a socket in the body of a fitting
before the nut being tightened;
[0033] FIG. 2 is a similar section showing the configuration of
components and location of the pipe when the nut is tightened onto
the body;
[0034] FIG. 3 is a central elevational section showing a dual pipe
coupling wherein one side the nut has been tightened and on the
other before being tightened;
[0035] FIG. 4 is a partial perspective cut-away view of a pipe
abutment surface according to a first embodiment of the
invention;
[0036] FIG. 5 is a partial perspective cut-away view of a pipe
abutment surface according to a second embodiment of the
invention;
[0037] FIG. 6 is a partial perspective cut-away view of a pipe
abutment surface according to a third embodiment of the
invention;
[0038] FIG. 7 is a detailed view of the pipe abutment surface of
FIG. 6;
[0039] FIG. 8 is a partial perspective cut-away view of a pipe
abutment surface according to a fourth embodiment of the invention;
and
[0040] FIG. 9 is a cross-sectional view of one of the projections
of FIG. 8.
DESCRIPTION OF THE PREFFERED EMBODIMENT
[0041] The following detailed description of the invention refers
to the accompanying drawings. Although the description includes
exemplary embodiments, other embodiments are possible, and changes
may be made to the embodiments described without departing from the
spirit and scope of the invention. Wherever possible, the same
reference numbers will be used throughout the drawings and the
following description to refer to the same and like parts.
[0042] There is shown in FIG. 1 a coupling with an inserted pipe
before tightening of the nut. The coupling 10 that engages the
outer surface of pipe 12 includes a body 14 that has a pipe
abutment surface 16 which is abutted by the end of the pipe 12 when
inserted into the coupling as shown in FIG. 1. The body includes a
further shoulder 18 whose diameter is smaller than that of the pipe
abutment surface 16.
[0043] The body 14 has a male thread 20, and between the outer end
22 of the body and the shoulder 18 is a generally annular planar
surface 24 which constitutes an abutment surface of a socket or
cavity 26 for a resilient gasket ring 28, abutment shoulder 18 of
the socket 26 being the inner end of the socket, the socket 26 also
having two cylindrical intermediate and axially outer walls 30 and
32 separated by a step 34 (three diameters in all), the diameter of
the outer wall 30 exceeding that of the inner wall 32.
[0044] Surrounding the pipe 12 is a compression sleeve 36, which
carries the resilient gasket ring 28 on its inner end, being fused,
bonded, or otherwise affixed to the end of the compression sleeve
36. This could alternatively be engaged by a mechanical tongue and
groove or otherwise affixed on the face end of the sleeve 36, and
the outer diameter of gasket ring 28 is less than the diameter of
outer wall 32 but greater than the diameter of intermediate wall
30, so that the compression sleeve can be readily inserted into the
body 14 with the gasket ring 28 being freely movable adjacent wall
32 but requiring compression by axial movement of compression
sleeve 36 to enter socket 26.
[0045] Adjacent but axially outwardly of sleeve 36 is a gripping
member 38 having radially inwardly but axially spaced barb
projections 40, and having an outwardly converging tapered surface
42. The gripping member 38 must be radially deformable, and thereby
circumferentially deformable, and is typically a split ring.
[0046] The nut 44 is provided with a tail 46 having an outwardly
converging inner tapered surface 48 the included angle of which is
approximately the same as the tapered surface 42 of the gripping
member 38, and inwardly from the outer end of tail 46 there is an
annular planar shoulder 50 which, upon tightening of the nut 44,
will bear against end surface 52 of compression sleeve 36.
[0047] The annular surface 54 of the flange at the outer end of
sleeve 36 is spaced axially inwardly a short distance from the
surface 52.
[0048] When the pipe 12 is inserted into the socket 26 of the
coupling as shown in FIG. 1, it abuts against the pipe abutment
surface 16. Initial tightening of the nut 44 on the body 14 will
not cause abutment of shoulder 50 with annular surface 52 of the
sleeve 36. The inner end of the gripping member 38 is loosely
contained within a recess 56 in the outer end of sleeve 36, and the
gasket ring 28, sleeve 36, and gripping member 38 move in together
with the nut 44 since there is a clearance of all portions of the
coupling around the polymeric pipe 12 when it is first inserted.
However, after the nut 44 travels a short axial distance inwardly
the gasket ring 28 is intercepted by the step 34 and will not pass
that step until compressed. Continued movement of the nut therefore
causes a small axially inward movement of the sleeve 36 and the
gripping member 38, and must be accommodated by the sliding of
inner surface 48 over the outer tapered surface 42, in turn causing
the barb projections 40 of the gripping member 38 to engage the
outer surface of pipe 12.
[0049] When the barb projections 40 have engaged the pipe, further
tightening of the nut 44 causes the pipe 12 to be forced inwardly
into the body 14. The longitudinal forces are such that the end of
the pipe 12 that abuts abutment surface 16 is compressed and/or
deformed so that it travels past surface 16 towards shoulder
18.
[0050] Tightening of the nut 44 (generally by rotation in the
clockwise direction) also brings the shoulder 50 into abutment with
the annular surface 52 of compression sleeve 36 and progresses the
sleeve 36 axially inwardly, causing sufficient compression of the
gasket ring 28 for it to enter the inner smaller diameter
intermediate portion 32 of the socket 26. The socket is of such
dimension that the gasket ring 28 effects a satisfactory seal
between the body 14 and the pipe 12, and this is further enhanced
when the nut 44 is fully tightened so that the two surfaces of the
sleeve 36 respectively lie in abutment with the outer end 22 of the
body 14 and the shoulder 50 as shown in FIG. 2. At this location,
compression of the resilient gasket ring 28 results in a seal,
which is effective against very high pressures.
[0051] Since the nut cannot be progressed any further inwardly, the
compression of both the rings 28 and 38 is controlled to lie within
the range dictated by the diameter of the pipe 12. In addition, the
longitudinal distance 66 between the abutment surface 16 and
shoulder 18 is generally equal to or longer than the longitudinal
travel of the nut when the barbed projections have first gripped
the pipe.
[0052] If the pipe 12 is not inserted into the body 14 and the nut
44 is screwed forwardly, the pipe 12 will not be able to be forced
inwardly to the body 14 unless the nut is screwed back to its loose
state.
[0053] When the nut 44 is screwed back (usually rotation
anti-clockwise) the compression sleeve 36 is also pulled back
(rearwardly) due to a loose engagement of the reverse tapered
surfaces 58 of compression sleeve 36 and 60 of nut 44, and
subsequent abutment of compression sleeve 36 against inner end of
gripping member 38. Because the gasket ring 28 is attached to the
inner end of sleeve 36 that is also withdrawn and does not remain
in the small diameter portion of socket 26.
[0054] As illustrated in FIG. 2, when sleeve nut 44 is tightened
over body 14, radially outstanding flange 62 of gripping member 38
lies adjacent shoulder 64 of nut 44. If a tensile load is applied
to pipe 12, and body 14 is fixed, any relative movement will
initially impart more radial compression to gripping member 38, but
such movement (if any) will be very small, and will be resisted by
abutment of flange 62 against shoulder 64.
[0055] Simultaneously, as the sleeve 44 is being tightened and the
projections 40 engage the pipe the pipe end 65 is forced past the
abutment surface 16 towards shoulder 18. When the pipe 12 is being
manually inserted it therefore allows the user to appreciate that
the pipe is in the correct position within the body 14 whilst there
still being sufficient room for further travel of the pipe inwardly
due to the tightening of the nut.
[0056] It will be appreciated that the assembly may be sold with
the components in place and held captive while nevertheless
retaining a clearance over the outer surface of pipe 12.
[0057] Illustrated in FIG. 3 is a two-pipe coupling, where the
coupling may be used to join two pipes together. As seen in that
Figure, the left hand side of the coupling 10a has had a pipe
inserted and the nut 44 is yet to be tightened with the end of the
pipe 65a abutting surface 16, whilst the end of the other pipe 65b
has had the pipe inserted and the nut 44 fully tightened whereupon
the pipe end 65b has moved past shoulder 16 and towards the
abutment surface 18. In this embodiment, the distance 66 between
the surface 16 and the shoulder 18 is generally greater than or
equal to the longitudinal travel of the nut 44 when the barbed
projections 40 have engaged the pipe 12. Thus when the nut 44 is
fully tightened the pipe 12 is positioned generally against or
adjacent shoulder 18.
[0058] As illustrated in FIG. 4 where there is shown a cut-away
partial perspective view of the body 14, the abutment surface 16
may be an annular step where the distance 66 between the surface 16
and shoulder 18 is greater to or equal to the full travel of the
nut. It has also been discovered that the annular step angle to the
longitudinal axis of the body may be a right angle for when being
tightened the nut produces sufficient longitudinal force that the
pipe is forced even beyond the right angle. However, those skilled
in the art will appreciate that the angle may be less than 90
degrees, provided that when the pipe is manually inserted, the user
feels sufficient resistance to assume that the pipe has been
inserted sufficiently deeply into the body.
[0059] Of course, those skilled in the art will readily appreciate
that the pipe abutment surface need not be a solid annular ring as
illustrated in FIG. 4, but could equally well be a plurality of
projections symmetrically circumferentially disposed within the
body 14 and positioned before the abutment surface 18. This is
illustrated in FIG. 5 where the abutment surface 16 is defined by
three wedges 68 located at 120-degree intervals within the body of
the pipe The length of the wedges is equal to the length 66 being
equal to or greater than the travel of the nut when fully
tightened.
[0060] Whilst FIGS. 4 and 5 illustrated the abutment surface having
a generally right angle to the longitudinal axis of the body, the
front face 67 of the wedges may be tapered to enable for easier
movement of the pipe towards the shoulder 18 when the nut is being
tightened. The angle has to be chosen so that when the pipe is
being manually inserted it is not easily possible to push the pipe
past the faces 67 so that the user feels as if the pipe has been
sufficiently inserted into the body. However, it has been
discovered that even angles of around 45 degrees are sufficiently
steep to provide an abutment surface 16 against which a pipe abuts
when manually inserted. Thus, as illustrated in this embodiment the
surface 67 includes two faces 67a and 67b whose apex 67c is at an
angle of some 70 degrees to the longitudinal axis of the body.
[0061] It is to be understood that where the abutment surface 16 is
defined by individual projections, the number of projections is not
necessarily three, and there may be more projections. In addition,
in such an arrangement, the angle of the front faces of the wedges
that define the surface 16 may vary for different projections. Thus
some of the projections may be right-angled whilst other at a much
gentler angle. The body of the pipe between the surface 16 and
shoulder 18 may also be of a non-smooth configuration to assist in
preventing the pipe from rotational motion when the nut is being
tightened.
[0062] Another alternative embodiment includes varying the total
length or orientation of the projections. Referring now to FIG. 8,
there is shown a plurality of projections 70 at right angles to the
longitudinal axis of the body. The projections are preferably hump
or arcuate shape in their cross-section, as shown in FIG. 9, the
configuration being such that a pipe will still abut against the
projections when manually inserted but will still enable the pipe
to pass the projections when under the force exerted by tightening
of the nut.
[0063] Some of the projections 70 may not extend all the way to the
shoulder 18 so that when the pipe reaches the shoulder it expands
outwardly and springs back into its natural shape. Similarly, with
a solid annular abutment surface as illustrated in FIGS. 1 and 2,
the diameter of the pipe 12 between the surface 16 and the shoulder
18 may be equal to that before the shoulder. Thus when the pipe has
been forced past the surface 16 its diameter increases so that the
end of the pipe is not caused to deform to the same degree.
[0064] Those skilled in the art will readily appreciate that there
are many alternative constructions of surface 16. As discussed
above it may be formed by a annular shoulder in the body of the
coupling or by including discrete projections whose size, shape and
orientation provides a sufficient surface area so that when a user
inserts a pipe into the body they know that they have inserted the
pipe as far is necessary whilst there still being sufficient room
to accommodate further movement of the pipe into the coupling when
tightening of the nut.
[0065] It is also to be understood whereas the above description
discussed a coupling having a particular configuration it is not
intended to limit the present invention to such a coupling and
other pipe couplings may includes the present invention. For
example, the present invention may equally well be applied in a
coupling as defined in Applicant's Australian Patent 707930. In
that invention, the sleeve of the coupling is dispensed with and a
spigot includes an annular flange that acts on the gasket to
provide a seal under tightening of the nut. The abutment surfaces
the subject of the present invention could very well be located on
the spigot so that the pipe can still move axially inwardly.
[0066] It is therefore intended that the present invention can be
applied to all pipe couplings of the type where a nut is used to
drive a grip ring that in turn engages and axially forces the pipe
further into the body of he coupling. The present invention thus
solves the problem of the end of such a pipe being deformed due to
no remaining longitudinal space for the pipe to travel through.
[0067] Whilst the foregoing description has set forth the preferred
embodiments of the present invention in some detail, it is to be
understood that numerous modifications, obvious to a person skilled
in the art, may be made without departing from the scope of the
invention. It is therefore to be understood that the invention is
not limited to the specific embodiments as herein described.
* * * * *