Note: Descriptions are shown in the official language in which they were submitted.
~3327~7
Convoluted Hose End Assemb1y
BacXqround of the Invention
This invention relates to insert fittings for convoluted
tubing and/or hose. More particularly, the invention relates to
~luid ~aaling efficiencies of hose-to-fitting coupling
mechanisms.
The majority of prior art fitting inserts for convoluted
hose and tubing have either entirely smooth, fully cylindrical
~ur~aces or have barbed project$ons emanating fr~m smooth
cylindrlcal surfaces. In some instances, grooved inserts are
utilized which have annular ridges believed to enhance the
crimping process, and hence efficiency, of the ~luid seal between
the tubing and nipple insert portions of the ~itting. Generally,
regardles~ o~ which type o~ nipple insert i3 utili2ed, tha
convoluted ~ubing end is compressed against the insert during the
crimping proce~, and the ~ndividual convolutlon3 tend to
collapsc in random ~olding pat~ern~, ~aking relatlvely di~ricult
tha task o~ esta~lishiny a r~liable ~luid ~eal. In fact, in m~st
applic~tions, potential leaks and variations as~ociated w~th
randomly compressed convoluted tubing become even ~ore difficult
to predict and control when the fittings are barbed or have
annular grooves over their cylindrical surfaces.
Ideally, a fitting insert would be designed such that the ~: :
collapse of convoluted tubing during ~he crimping step could be
?~ :
~3327~7
controlled in a ~anner to assure and evsn to e~hance fluid
sealabilityO
Summary of the Invention
The insert fitting of the present invention provides a
superior fluid seal for convoluted hose. In accordance with the
invention, the insert ~itting has a dimensional relationship with
the convoluted hose with which it is designed to mate. The
fitting, particularly suitable for use with hose made of
polytetrafluoroethylene material, has a shape which directs and
controls the collapse of the tubing convolutions during crimp~ng
to a nipple insert. In a preferred form, the fitting includes a
generally cylindrical nipple insert which contains a pair of
annular sealing surfaces and a relie~ region positioned between
the ~ur~aces. The nipple insert has a longitudinal axis, and the
surfaces are spaced along the axis. The relie~ region
intermediate the surfaces comprises a diameter les3 than that o~
each of the sealing sur~aces. Each o~ the ~ealing sur~ce~ is
g~n~rally radially equal d~stant at all point~ ~rom the
longitudinal axis oP the insert. Each of the spac~d sealing
~ux~ces ha~ a longitudinal wid~h in the range o~ 75-100~ o~ the
pitch width o~ the convoluted ho~e.
Brief DescriPtion of the Drawings
Figure 1 is a fragmentary cross-sectional view of a
convoluted hose end with a prior art nipple insert adapted for
sealingly engaging the hose, prior to crimping the hose about the
nipple insert.
~ '
~33~7~7
Figure 2 is a fragmentary view similar ~o that o Figure 1
with the exception that the hose has been crimped to the insert.
Figure 3 is a fragmentary view of a preferred embodiment of
the present invention which includes a hose end fitting in
combination with a convoluted hose end prior to crimping.
~ igure 4 is a view similar to that O.e Figure 3, but shown
a~ter the crimping process.
Detailed Description of the Preferred Embodim;~e~
Referring initially to Figures 1 and 2, a prior art
convoluted hose end assembly 10 is shown in a ~ragmentary cross-
sectional view. The assembly 10 includes a hose end fitting 12
which includes a nipple insert 14. The insert 14 extends into a
convoluted hose end 16, here shown as a hose or tubing ~ormed of
polytetra~luoroethylene material. A wire ~raid 6heath 18
provideR a cover over the polytetrafluoroethylen~ tubin~ ~or
purpo~es o~ providing strength to the ho~e assembly. The sheath-
tublng combination enhancas tXe burst pressure rating for the
~luid aonveying structure. A crimp collar 20 surround~ the
nipple in~Qrt portion 14 o~ the end ~itting 12, overlying the
convoluted hose end 16 as well as the wire braid sheath 18. The
collar 20 is compressed radially inwardly over the nipple insert
14 for providing securement of the end fitting to the hose end.
Figure 1 is a view at a time prior to the compression of the
crimp collar, while Figure 2 is a post-compression view,
~3327~7
Referring now more particularly to Figure 2, it will be
appreciated by those skilled in the art that the cylindrical
exterior of the insert 14 i~ of a smooth contour, having no
grooves or barbs. With such a configuration, the crimping
result will typically comprise a random collapsing of the
convoluted tubing or hose member 16. However, Figure 2 depicts
the most ideal compression of the hose end 16 after the crimpi.ng
process, in which the collapse has occurxed as uniformly as
po~sible. Nonetheless, it will be appreciated by those skilled
in the art that ther~ remains significant potential for leakage
as depicted by the helical leak path 24. This demonstrates that
even under the best of conditions of hose end collapse about the
nipple insert 14, a crimping process which provides ~or no
~lattening o~ convolutions appears to inherently invite leakage.
Referring now to Figures 3 and 4, a preferred embodiment 40
of the convoluted hose end assembly o~ the present invention i9
~hown. The asse~bly 40 provides a pre~erred embodi~ent oP an end
Pitting 30, which includes a nlpple insert 32 having a ~ontoured
exterior sur~ace Por the purpose of creating a controlled
coll~ps~ Or ~he tubing end during crimping thereof to the nipple
in~ert. It will be noted that the insert 32 includes a pair of
raised cylindrical sealing surfaces 34 which are spaced apart. A
relie~ region 37 is positioned between the surfaces 34. It will
also be appreciated that the pitch width (the length of one cycle
of hose convolutions) of the hose 16 for use therewith has a
value egual to "p". In the invention as herein described, each
~3~7~
sealing surface 34 will have a longitudinal width as measured
along axis l'a-a~ equal to the value i'p-'. This inventor has ~ound
that the relationship of the longitudinal width of the sealing
surfaces to the pitch width of the hose creates a collapse Df the
convolutions as shown in Figure 4, wherein the hose becomes
flattened as shown at 42, directly over each sealing sur~ace 34.
Intermediately o~ the sealing surfaces (i.e., at the relief
region more particularly described hereinafter), a random
collapse or crush portion is developed, as shown at 44. Thus,
although the convolutions flatten out at th2 sealing surfaces 34,
the convolutions overlying the relief region have a random crush
p~ttern. Thus the invention provides an ideal sealing system at
the raised cylindrical sealing sur~aces 34, while any additional
effective sealing which is achieved within the reli~ region 37
although desirable is incidental.
In the preferred ~orm, the relief region includes a reduced
diameter portion 36 which has a longitudinal length measured
along the axis "a-a" equal ~o or greater than one pitch width
"p". T~e amoun~ o~ reduction Q~ the diame~er has to ~e
det~rmined by trial and error, to the ~xtent that thi~ inventor
has ~ound that the preferred reduction is greater for hoses o~
increasing size. E'or example, a convoluted hose having a
diameter of 2 inches will require more of a reduction in diameter
in the relief region than will a hose having a 1/2 inch diameter.
~t the boundaries of each reduced diameter segment 36 are relief
ramps which join the reduced diameter portions to the sealing
.
~3~7~7
surfaces. In the preferred form, this inventor has determined
that the ramps may have an angle ~ithin a range o~ 10-25 degrees
as measured with respect to the axis "a-a".
The preferred form o~ this invention utilizes at least two
sealing surPaces 34, each having a single relie~ region 37
thereb~tween. ~he relief region 37 has been defined to have a
reduced diameter portlon 36 equal to at least one pitch width, or
a value 0~ I-p-~. Sealing surfaces positioned at the extremities
of the insert each have one relief zone. Relief zones are
distinguished from relief regions by the fac~ that the zones are
not bounded on both sides by sealing surfaces, nor do the zones
have any special dimensional relationship to the pitch width o~
the ho~e. Relie~ zones also may exist as a single relief ramp 38
as 5hown by the relief zone 39 at the rightward extremity of the
nipple insert 32. Conversely, a rel1~f zone may include a
r~duced diameter portion 36 as well a~ a relie~ ramp 38 a~ per
the relie~ zone 29 shown at the lefthand extremity o~ the nipple
insert 3~. It will be apparent to thosa ~killed in the art that
a relie~ zone will include a~ least one relia~ ramp~ T~e
int~nded purpo5e of relie~ zone is to provide reliQ~ ~or the
convolutions whlch spread outwardly of the sealing zone during
the crimping process. By contrast, a relief region, which li~s
intermedia~ely of any two sealing surfaces 34, always de~ines a
reduced diameter portion 36 having two opposed relief ramps 38 on
either side o~ the portion 36.
~ 3 3~
In the preferred ~orm as described herein, the sheath 18 is
of a metallic wire braid havins a herringbone pattern. A steel
braid sheath will provide optimal strength for this purpose.
Finally, in the preferred form, the ~ealing ~urfaces, relief
regions, and relief zones of the nipple insert 32 are all
annular, and each comprises a zero helical angle. $his is
pre~erred, even though the convolutions o~ the hose 16 are
helical. This i~ventor has determined that the use of a
"zero helix" or annular 6ealing ~urface provides a pre~erred
mechanism ~or initiating the flattening of th~ convolutions
which occurs during the crimping step over the ~ealing sur~ace~
34 as shown at 42. Also in the preferred form, this inventor has
determined that there is some flexibility with respect to
longitudinal width o~ the sealing sur~aces. Hence a pre~erred
range o~ 75~ to 100% of the pitch width for the width o~ the
sealing surfaces 34, regardless of the hose ~ize, will provide
the desired ~lattening e~ect to achieve ~n improved ~eal. This
lattitude may, in ~act, be attributable to use o~ an annular-~o-
helical relation9hip betwaen the nipple in~ert sealing sur~aces
and ho~e convolutions, although this i9 only ~peculati~n.
Althou~h only one preferred embodiment has béen d~tailed and
described herein, the appended claims are envisioned to cover
numerous alternate embodiments which are nei~her shown nor
described herein.
