Quick action self-locking pipe fittings

Described is an improved pipe fitting of the self-locking quick action type wherein the leakproof seal is provided by a forced insertion of the extremity of a pipe inside a conical seat without utilizing any gasket of resilient material and wherein the release of the pipe anchoring means may take place only rotating an external crown of a plug in a stable position visibly recognizable by alignment or off-setting of two external indexes.

The present invention relates, in general, to pipe fittings for pipings 
made with flexible, semirigid or substantially rigid pipes of plastic 
material or metal. More particularly the invention relates to fittings of 
the quick coupling type, that is of the type wherein the pipe is forcibly 
pushed inside the fitting for establishing the necessary leakproof joint 
and wherein it is automatically locked in such an engaged position by an 
elastic anchoring element having claws abutting against the outer surface 
of the pipe preventing its extraction unless acting upon suitable release 
means when the connection must be undone. 
Fittings of this kind are widely used for making pneumatic and oleodynamic 
systems, in laboratories and in fluids conveyance systems utilizing tubes 
of small or medium diameter. 
The quick action fittings of known types utilize a "O-ring" fitted in an 
appropriate seat of an internal cylindrical surface of the fitting in 
order to establish a leakproof seal with the external cylindrical surface 
of a pipe (of compatible diameter) forcibly inserted into the fitting. The 
anchoring element is commonly represented by an elastic washer, suitably 
housed inside the fitting in an outer axial position with respect to the 
position of the "O-ring" gasket, and having a plurality of radial teeth or 
claws extending inward from the inner circumference of the ring of the 
washer for a distance sufficient to have them engaged by the pipe pushed 
inside the fitting and from this flexed towards the interior of the 
fitting in such a way that when the insertion of the pipe is completed the 
tips of such claws abut against the external surface of the pipe with a 
certain angle of incidence thus preventing it from being pulled back out. 
The means for releasing the grip are typically formed by a cylindrical 
sleeve inserted inside the fitting and extending outside the rim of the 
fitting's nipple and through which passes the pipe inserted in the 
fitting. Such a sleeve though being prevented from coming out of the 
fitting by suitable retaining means, may be pushed towards the interior of 
the fitting in order that its internal rim push on the claws of the 
elastic washer flexing them further towards the interior of the fitting 
until releasing their grip on the external surface of the pipe which may 
be thus easily pulled out of the fitting. 
The prior art fittings have different disadvantages and present some 
non-negligeable problems during the assembling of the pipings as well as 
in relation to maintaining a leakproof seal in time. 
Firstly, the type of sealing utilized, i.e. "O-ring" type, imposes a 
careful handling of the pipes in order to preserve an accurate cylindrical 
shape and freedom from abrasions and scratches of the end of the pipe 
which must be inserted in the fitting. This often requires a repeated 
clipping of the pipe until achieving the desired leakproof seal. 
A second disadvantageous aspect of the prior art fittings is due to the 
fact that the sealing element is necessarily made of a resilient material 
essentially different from the material forming the fitting and the pipe. 
Such a resilient gasketing material must therefore possess the necessary 
chemical inertness in respect of the particular fluid conveyed besides the 
resistance to the particular temperature of operation, further it tends to 
loose the original resilience characteristics with time, thus often 
causing leaks from the joint. 
Furthermore, the means for releasing the grip on the pipe inserted in the 
fitting may be acted upon erroneously or accidentally. 
A main objective of the present invention is, therefore, to provide a quick 
action self-locking fitting more convenient in use of the prior art 
fittings and free of the above mentioned drawbacks and inconveniences of 
such known fittings. 
These objectives and advantages are accomplished by the quick action 
self-locking fitting made in accordance with the present invention wherein 
the desired leakproof seal is made without utilizing any resilient 
gasketing element but simply by compression of the pipe end inside a 
conical seat of the fitting and wherein the means for releasing the grip 
on the pipe inserted in the fitting have at least two stable positions 
allowing the extraction of the pipe from the fitting only when they are in 
one of said two positions. 
Essentially the quick action self-locking fitting of the present invention 
comprises a suitable hollow body which may assume different forms, as it 
will be described later, having at least a tubular projection or nipple, 
said nipple having, on at least a portion of its length, an internal 
truncated cone surface (conical seat) with its major base oriented towards 
the external aperture of said nipple and apt to form a seal directly 
against the rim of a pipe pushed inside said nipple of the fitting and 
having an external cylindrical surface provided with at least a collar; 
an elastic anchoring washer placed on the rim of said nipple and provided 
with a plurality of claws radially extending from its inner circumference 
and long enough to be flexed elastically towards the interior of the 
fitting by said pipe preventing extraction of the latter; 
an outer tubular sleeve snapped on said nipple until receiving said collar 
in a suitable seat on the internal surface of said outer sleeve, the 
internal surface of said outer sleeve being provided with a first gorgerin 
or step blocking said elastic washer against the rim of said nipple in 
correspondence of the outer perimeter of said washer; 
a plug formed by a crown and a tubular appendix having a cylindrical 
central hole of diameter sufficient to allow said pipe to pass through the 
plug, said plug, by means of said appendix, being forced inside said 
sleeve by forcing a collar of said tubular appendix beyond a second step 
of the internal surface of said sleeve in such a way that the crown of the 
plug remains outside said sleeve; 
means in said plug and said sleeve allowing an axial displacement of said 
plug relative to said sleeve by rotating the plug by means of said 
external crown between at least two distinct angular positions thereof in 
such a way that, in a first angular position said plug is advanced inside 
said sleeve until the rim os said tubular appendix elastically flexes the 
claws of said washer further towards the interior of the fitting, 
diverging them and freeing said pipe so that it may be pulled out, and in 
a second angular position said plug is retracted and cannot be pushed 
inside said sleeve. 
Preferably said cooperating means in said plug and in said sleeve comprise, 
respectively, beadings or projections on the face of said crown opposing 
said sleeve and indentations on the rim of said sleeve. More preferably 
said beadings are in number of three angularly spaced at 120.degree. one 
from the other while the rim of said sleeve is provided with three 
relatively deep indentations angularly spaced at 120.degree. one from the 
other and with three relatively shallow indentations intermediate to said 
deeper indentations.

The pipe fitting shown in FIG. 1 is composed of a hollow body 1 which, in 
the embodiment shown, has an extremity 2 provided with a conical thread 
for sealingly screwing into a threaded hole of a vessel or of a manifold 
or of a threaded sleeve etc. and a tubular extension or nipple 3 having an 
internal truncated cone surface 4 (conical seat) and at least a collar 5 
on the external cylindrical surface of said nipple; of an elastic 
anchoring washer 6 provided with a plurality of radial teeth or claws 7 
projecting towards the interior from the inner circumference of the 
washer's outer ring; of a sleeve 8 having a seat 9 in a first internal 
cylindrical surface 10, a first gorgerin or right angle step 11, a second 
gorgering or step 12, preferably tapered, and an external rim 13 having a 
number of indentations 14a (14b) evenly distributed along the rim's 
circumference; and of a plug 15 formed by a crown 16 and a tubular 
appendix 17, the latter having a relief portion in the shape of a collar 
18 near its inner extremity. Preferably the tubular appendix 17 of the 
plug has one or more, preferably two, longitudinal cuts 19 extending from 
its internal extremity for a considerable portion of its length, while on 
the face of the crown 16 opposed to the rim of said sleeve there are a 
number of beadings or projections 20 evenly distributed along the 
circumference. 
The body 1, in the particular embodiment shown, is provided both with an 
external hexagon 1a permitting the use of a normal spanner for turning the 
body 1 as well as an internal hexagon 1b allowing, alternatively, to use a 
hexagonal wrench instead of the normal external spanner. 
The conicity (i.e. the angle comprised at the vertex by two diametrically 
opposed generatrices of the internal truncated cone surface 4 of the body 
1), is preferably comprised between 3.degree. and 4.degree. even though 
conicities slightly greater or slightly lower than said preferred limits 
may be used without particular problems. 
FIGS. 2 and 3 are respectively lateral views of the pipe gripping elastic 
washer 6 (FIG. 2) and of the external rim 13 of the sleeve 8 (FIG. 3). In 
this latter Figure is shown the disposition along the circumference of the 
rim of the sleeve of the plurality of radial indentations 14a and 14b. The 
indentations 14a are deeper than the indentations 14b interposed to the 
first ones. 
FIG. 4 shows the assembled fitting. 
The same numerals are used for indicating the same parts in all Figures. 
As it may be observed from the Figure the assembly of the various parts 
forming the fitting takes place by firstly placing the washer 7 on the rim 
of the nipple 3 of body 1 of the fitting. The sleeve 8 is then snapped-on 
by exerting a compression force sufficient to bring the collar 5 of the 
nipple 3 of the body of the fitting into the relative seat 9 of the first 
internal cylindrical wall of the sleeve 8. The first right angle step 11 
of the internal surface of the sleeve 8 comes to abut against the 
peripheral surface of the washer 6 thus providing to block the washer 6 in 
position. Finally the plug 15 is inserted inside the sleeve 8 by exerting 
a compression sufficient to bring the collar 18 beyond the tapered step or 
relief 12 which prevents extraction of the plug. The subsequent 
longitudinal cuts 19 of the tubular appendix of the plug 15 favour a 
certain elastic constriction of the tubular appendix of the plug during 
its forced insertion inside the sleeve 8. At the same time the beadings 20 
on the internal surface of the crown 16 of the plug 15 will abut either 
against the outermost edge of the rim 13 of the sleeve 8 or in one or in 
the other of the indentations 14a and 14b present on such a rim 13. The 
relative dimensions of the matching between the sleeve 8 and the plug 15 
are such that the tapered step 12 exerts a certain elastic pull action 
towards the interior of the fitting upon the collar 18 of the plug 15 when 
the beadings 20 are not inside the deep indentations 14a. The pull-in 
action is favoured by the ability of the tubular appendix 17 to be 
elastically constricted by virtue of the longitudinal cuts 19. 
As it may be easily observed, the assembly is such that the parts composing 
it are assembled through a snap-on action one into the other and, though 
maintaining the ability to rotate one with respect to the others and, for 
what concerns the plug 15 of being able to assume at least two different 
pre-determined stable axial positions, are no longer separable. 
Such an assembly system of the fittings of the invention does not require 
tools and/or special implements as it is commonly the case instead with 
the state of the art fittings and represents a non-negligeable advantage 
with respect to the latter. 
The fitting is now ready to receive a pipe 21 having an external diameter 
compatible with the diameter of the particular coupling. In FIG. 5 is 
shown the pipe 21 stably coupled in a leakproof manner to the connector by 
pushing the pipe itself with a sufficient force inside the conical seat. 
The pipe 21 (of diameter compatible with the particular fitting) is 
inserted through the cylindrical hole of the plug 15 which has a diameter 
such as to conveniently act also as a guide for the pipe being inserted. 
The pipe 21 is pushed inside the conical seat 4 of body 1 of the fitting 
exerting a compression sufficient to establish a perfect leakproof seal of 
the connection. The moderate conicity of the seat favours a gradual 
compression of the external edge of the rim of the pipe 21 facilitating a 
perfect conformation between the contacting surfaces even in case of 
imperfect cuts of the pipe itself. Upon isertion the pipe 21 flexes 
elastically the radial claws 7 of the elastic anchoring washer 6 towards 
the interior of the fitting with respect to their rest inclination; when 
insertion is completed the tips of the radial claws 7 will result abutting 
with a certain incidence angle against the external surface of the pipe 21 
as to prevent its retraction. 
When desiring to pull out the pipe thus inserted into the fitting, the plug 
15 will be rotated until allowing the beadings 20 to fall into the deep 
indentations 14a of the rim of the sleeve 8, preferably, under a certain 
pull-in action exerted by the tapered step 12 on the collar 18 of the 
tubular appendix 17 of the plug 15 favoured by a certain capacity of 
constriction of the tubular appendix 17 by virtue of the longitudinal cuts 
19. 
In this position, the rim of the tubular appendix 17 comes near the 
inclined claws 7 of the pipe anchoring washer and a slight pressure on the 
external crown 16 of the plug 15 is sufficient for the rim of the tubular 
appendix 17 to push the claws of the anchoring washer to open themselves 
more thus freeing the pipe 21 which may be easily disconnected by simply 
pulling it out. Of course the deep indentations 14a are sufficiently deep 
for allowing such a final forced advancement of the plug 15 inside the 
fitting in order to free the pipe from the grip exerted by the claws 7. 
Conveniently, as shown in FIG. 6, on the respective lateral surfaces of the 
crown 16 of plug 15 and of the sleeve 8 there are suitable indexes, e.g. 
in the form of projections or indentations, 22 and 23 apt to visibly 
showing the actual position of the plug 15. Moreover the crown 16 may have 
a grooved surface for facilitating its rotation to the desired position. 
The shallow indentations 14b intermediate to the deep indentations 14a have 
the sole objective of determining, in the rotation movement of the plug 15 
with the beadings 20 outside the deep indentations 14a, an equal number of 
certain angular positions such that the external indexes 22 and 23 result 
either positively offset or aligned in order to make more easily 
recognizable the actual position of the plug. 
Therefore by placing the plug 15 in its "safety" position, e.g. with its 
beadings in the shallow indentations 14b easily recognizable by the 
relative offset position of the external indexes 22 and 23, the joint 
can't be undone following, for example, an erroneous intervention. Only by 
rotating the plug until, for example, aligning the external indexes 22 and 
23, the connection may be undone. This represents a further improvement 
with respect to the fittings of the state of the art. 
Another extremely advantageous aspect of the pipe anchoring system of the 
fittings of the invention is represented by the fact that when the plug 15 
is in its stable backed "safety" position, that is with the beadings 20 in 
the shallow indentations 14b, the collar 18 of the tubular appendix 17 
forces against the tapered step 12 of the internal surface of the sleeve 8 
and determines a constriction of the diameter of the tubular appendix 17 
(favoured by the longitudinal cuts thereof 19). In practice the terminal 
portion of the appendix 17 clasps the external surface of the pipe 21 
inserted into the fitting effectively acting as a vice on the pipe itself. 
This blocking action on the pipe is stably maintained by the plug 15 until 
it is rotated into its "release" position, that is when the beadings 20 
are aligned with and allowed to fall into the deep indentations 14a. 
Such a blocking action is extremely effective in preventing accidental 
disengagements of the pipe from the grip of the claws of the anchoring 
washer under strong vibrations possibly transmitted to the pipe during 
operation of the plant or of the machine, besides constituting, in any 
case, a positive additional safety factor upon the stability of the joint. 
The fitting according to the present invention may be fabricated with 
different materials each one suitable to particular applications. 
Therefore the fittings may be fabricated with metallic materials or with 
resins with the exception of the anchoring washer 6 which may be metallic 
in all instances. Manufacturing the fittings of the invention with 
thermo-plastic resins is particularly preferred for all applications 
wherein such materials are suitable in so far it permits manufacturing by 
molding of of the various parts forming the fitting without requiring any 
machining. 
Of course the choice of the particular thermo-plastic resin may depend, in 
a large measure, upon the type of application and of conveyed substance. 
Suitable are therefore all moldable thermo-plastic resins such as for 
example: polyvinyl acetate, polyamide and polycarbonate resins, modified 
PTFE (moldable), polyvinylidenefluoride, polypropylene, poly-ethylene, 
PVC, etc. 
It is further intended that the fittings according to the invention may 
assume different shapes, in particular the body 1 of the fitting may have 
different shapes and have more nipples for the connection of so many 
pipes. 
In FIGS. 7a, 7b, 8, 9a, 9b, 10a, 10b and 11 are shown different types of 
fittings in accordance with the present invention wherein the body 1 
assumes, every time, a different shape. 
A possible advantageous embodiment of the fittings of the invention, shown 
in FIG. 12, contemplates the possibility, for different fittings (A, B and 
C), to be force coupled one with the other in such a way as to form a 
distributor or manifold provided with an unlimited number of connection 
points with so many branch pipes. 
Fittings of this type are provided with a male (24) or a female (25) 
coupling means. Coupling takes place by forcing the male terminal 24 of 
one fitting inside the female seat 25 of another fitting until bringing 
the sealing collar 26 of the male terminal to fit in the appropriate seat 
27 formed by a circular groove in the internal cylindrical surface of the 
female terminal 25. 
Such an embodiment of the fittings of the invention is particularly 
suitable in the case the fittings be fabricated with plastic material. 
Though only few particularly preferred embodiments of the fitting of the 
invention have been illustrated, it is intended that modifications may be 
made by the expert technician though remaining within the scope of the 
invention. In particular other means may be utilized for forcing, by 
rotating it, the plug 15 in two distinct stable axial positions, for 
example a short length of helical groove on the internal surface of the 
sleeve 8 co-operating with a matching projection of the external wall of 
the tubular appendix 17 of the plug may be utilized as an alternative to 
the system described in the Figure. 
Alternately such a helical type coupling between the plug 15 and the sleeve 
8 could also be realized between the external surface of the sleeve and a 
sufficiently elongated inner surface of the external crown 16 of the plug 
in a manner easily understood by an expert technician. 
In accordance with these latter possible embodiments of the fittings of the 
invention, the plug may be advanced until parting the claws of the pipe 
anchoring washer simply rotating the plug until a certain stable position 
to which it will correspond the appropriate alignment of the external 
indexes for indicating that the plug has reached the "release" position 
and that the pipe may be pulled out of the fitting. A counter rotation (or 
a further rotation of the plug) will make the plug to back again to its 
"safety" position. Such an alternative way to realize the anchoring and 
releasing system of the fitting of the invention may contemplate allowing 
the pulling out the pipe without necessarily having to exert any pressure 
on the plug. This may result advantageous in case of joints located in 
places difficult to reach allowing to undo the connection using only one 
hand.