DESCRIPTION

Field of the invention

The present invention generally regards the technical field of fittings for pipes, and it particularly regards a metal screw fitting for gas pipes.

State of the Art

Various types of pipe fittings designated for transporting gas, for example the copper pipes present in a refrigeration and/or conditioning system.

Such fittings for gas pipes must guarantee, besides naturally a sufficient mechanical sealing on the pipe, a high pneumatic sealing with respect to the gas. The latter is necessary in light of the fact that in such pipes the gas generally circulates at a considerably high pressure.

To this end, often used are elastomeric gaskets or, for example as illustrated in FIG. 1C, conical copper gaskets GC.

In the latter case, inserted outside the surface is a rigid bushing BR, while the internal of the pipe is inserted into a metal core AM. The latter and the rigid bushing BR are then radially compressed to guarantee the mechanical sealing on the pipe.

Furthermore, for example as illustrated in FIG. 1A, obtained on the edge of the pipe is the so-called "folder" C, i.e. conical gaskets obtained by deforming the pipe.

Another possible solution for guaranteeing the mechanical sealing of the pipe and the soldering of a bushing B thereof, as illustrated in FIG. IB and as disclosed in the United States patent application n° US2014/0339818. A gasket GC is then arranged on the bushing B.

All such known solutions reveal some disadvantages.

For example, the elastomeric gaskets are only compatible with some types of gas and, over time, they reveal a particularly high wear.

On the other hand, the obtainment of the folders and/or the soldering requires the use of appropriate tools and a particular technical expertise.

A disadvantage common to all solutions of the prior art lies in that the pneumatic sealing reduces over time, with ensuing more or less leakage of gas from the pipe and the need to replace the gasket or the entire pipe. Document FR1335121 reveals a fitting for hydraulic pipes including a clamping element embedded in an elastomeric gasket.

Summary of the invention

An object of the present invention is to at least partly overcome the aforementioned drawbacks, by providing a metal fitting that is highly functional and inexpensive.

A particular object of the present invention is to provide a fitting that is particularly easy to use for any operator of the sector, even if not particularly specialised.

A particular object of the present invention is to provide a fitting that does not require particular tools so as to be made operative.

Another object of the invention is to provide a fitting capable of guaranteeing an optimal mechanical and pneumatic sealing of the gas pipe.

Another object of the invention is to provide a fitting that can be used independently from the type of gas transported in the pipe.

A further object of the invention is to guarantee the pneumatic and mechanical sealing of the pipe over time.

These and other objects to be further clarified hereinafter, are achieved by a fitting having one or more of the characteristics described and/or claimed and/or illustrated herein.

Advantageous embodiments of the invention are defined according to the dependent claims.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent in light of the detailed description of some preferred but non-exclusive embodiments of the invention, illustrated by way of non-limiting example with reference to the attached drawings, wherein:

FIGS. 1A, IB, 1C illustrate some solutions of the prior art;

FIGS. 2A and 2B are respectively a front and axial sectional view of an embodiment of the ring nut 30;

FIGS. 2C and 2D are respectively an axonometric and axial sectional view of the clamping element 10 part of the screw fitting 1;

FIGS. 2E and 2F are respectively a front and axial sectional view of the threaded coupling end member 40; FIGS. 3 to 7 are axial sectional views of the fitting 1 upon the mutual screwing of the ring nut 30 and the threaded coupling end member 40 in different operative steps, with in FIGS. 3A, 4A, 5A, 5B, 6A and 7A some enlarged details;

FIG. 8 is a schematic view of the end portion F of the pipe P after the full mutual screwing of the ring nut 30 and of the threaded coupling end member 40;

FIGS. 9A, 9B, 10A, 10B, 11, 12 and 13 are various embodiments of components that include the threaded coupling end member 40;

FIG. 14 is an axial sectional view of a further embodiment of the ring nut 30;

FIG. 15 is an axonometric view of elastic ring 50;

FIG. 16 is an axial sectional view of the assembly consisting of a ring nut 30, elastic ring 50 and clamping element 10.

Detailed description of some preferred embodiments

With reference to the mentioned figures, herein described is a screw fitting 1 for pipes P, which may be of any type.

In particular, the fitting 1 is particularly indicated for pipes P for transporting gas, said gas pipes being of the type for example present in an air conditioning system. Suitably, such gas pipes P may be made of metal material, for example copper.

Advantageously, the fitting 1 may be without elastomeric gaskets. This will allow avoiding the disadvantages described above.

In any case, in a pipe P, which may define an axis X, there may be distinguished an end portion F and an end edge E.

The present invention has various parts that are equal or however equal to each other. Unless otherwise specified, such parts that are equal or similar will be indicated with a single reference number, it being intended that the indicated characteristics are common to all equal or similar parts.

The fitting 1 may essentially comprise a ring nut 30, a threaded coupling end member 40 and a clamping element 10, coupled coaxially to each other.

The ring nut 30, the end member 40 and the clamping element 10 may be made of metal material, for example brass or steel.

As observable from FIGS. 9A, 9B, 10A, 10B, 11, 12 and 13, the threaded coupling end member 40 may be an integral part of various components for gas lines, for example valves as illustrated in FIGS. 9A to 10B or fittings of various types as illustrated in FIGS. 11 to IS.

The ring nut 30 may be of the type that can be screwed on the threaded coupling end member 40 with the interposition of the clamping element 10. Upon such screwing, the pipe P may be inserted into the threaded coupling end member 40, with the ring nut 30 and the clamping element 10 fitted onto the outer surface thereof.

In order to allow the screwing, the ring nut 30 may have an outer surface 31 suitable to be gripped by an operator or be engaged by a special tool, for example a spanner.

It is clear that even though the ring nut 30 will hereinafter be indicated as of the type that can be screwed onto the threaded coupling end member 40, the opposite may also occur, i.e. that the latter be of the type that can be screwed, or both be of the type that can be screwed one with respect to each other, without departing from the scope of protection of the attached claims.

As particularly illustrated in FIGS. 2C and 2D, the clamping element 10, which for example may be made of brass or steel, may have two or more gripping clamps 11 integrally joined and transversely extending from a support rigid ring 12.

It is clear that the clamps 11 may be of any number, as long as greater or equal to 2, without departing from the scope of protection of the attached claims.

As observable more in detail hereinafter, the screwing of the ring nut 30 onto the threaded coupling end member 40 may promote the radial compression of the clamps 11 onto the pipe P, which will be deformed up to forming an annular gripping groove G.

The latter will allow a permanent mechanical connection between the pipe P and the clamping element 10.

To this end, the hardness of the metal material of the clamping element 10 may be greater than that of the metal material of the pipe P. Furthermore, the metal material of the clamping element 10 may have a greater rigidity so as to be permanently deformed on the pipe P. In other words, the clamping element 10 may be deformed plastically and not elastic.

Due to such deformation, the assembly between the pipe P and clamping element 10 will be of the unitary type.

Each of the clamps 11 may have two end portions, a first one 1 facing towards the rigid ring 12 and a second one 11" in an opposite position.

Suitably, each end portion 11" may be radially expanded to define a jaw 110 suitable to form the aforementioned gripping groove G.

Preferably, an annular groove 13, which facilitates the controlled radial compression of the clamps 11 may be interposed between the rigid ring 12 and the first end portions 1 .

The latter may also have an outer surface 14 and an inner surface 15.

The outer surface 14 may be designated to remain faced to the inner part of the ring nut 30 and the inner portion 42 of the threaded coupling end member 40, while projections 16 for gripping on the pipe P may be present on the inner surface 15.

Advantageously, the clamps 11 may substantially be defined by circumferential arcs, which may be arranged consecutively adjacent to each other and spaced by a distance d, as illustrated in FIG. 2C.

Thus, the radial compression of the clamps 11 will cease when the same will come into mutual contact.

As particularly illustrated for example in FIG. 5A, the gripping groove G may have a depth p substantially equal to the distance d.

Suitably, the rigid ring 12 may have a first and a second substantially curved annular portion 12', 12" suitable to come into contact respectively with a first and a second inner surface 32, 33 of the ring nut 30.

Thus, the points of mutual contact between the latter and the clamping element 10 may be defined by single points of tangency 32', 33', so as to allow avoiding possible torsions of the pipe P upon the mutual screwing of the ring nut 30 and the threaded coupling end member 40.

In a preferred but non-exclusive embodiment, illustrated for example in FIG. 14, the ring nut 30 may comprise a groove 36 extending externally with respect to the surface 33.

The latter may for example have an angulation g comprised between 20° and 30°, and preferably 25°.

Such groove 36 may house an elastic ring 50 susceptible to come into mutual contact with the rigid ring 12 in a contact portion 12'" and with the inner surface 35 of the groove

36.

Thus, the rigid ring 12 may remain interposed between the ring 50 and the inner surface 35. More precisely, the rigid ring 12 will impact against the elastic ring 50, so as to remain in operative position. In order to simplify the assembly of the fitting 1, the elastic ring 50 may pass from a minimum radial expansion position that allows the insertion thereof into the ring nut 30 to a maximum radial expansion to allow the snap-insertion thereof into the groove 36 of the ring nut 30 and prevent the axial slipping off of the rigid ring 12, which will however be free to rotate in the ring nut 30.

To this end, an operator may elastically force the elastic ring 50 from the maximum expansion position towards the minimum expansion position. As a matter of fact, the maximum expansion position is the same that the elastic ring 50 takes when inoperative, i.e. when it is not subjected to external stresses.

Thus, the clamping element 10 and the ring nut 30 may form a unitary assembly.

Advantageously, the ring 50 may be made of plastic material, for example nylon 6,6.

The ring 50 may substantially be C-shaped comprising two ends 51, 51' faced to each other susceptible to be approached and moved away respectively when the ring 50 is in the minimum and maximum radial expansion positions.

Preferably, the ring 50 may have a predetermined maximum thickness SI substantially equivalent to the distance dl between the inner surface of the ring nut 30 and the outer surface 14 of the clamping element 10.

Suitably, the inner portion 42 of the threaded coupling end member 40 may comprise two frusto-conical surfaces 43, 44, coaxial and convergent with respect to the axis X, a sliding surface 48 interposed between them and an abutment surface 45.

Preferably, the first frusto-conical surface 43 may have a first angulation a comprised between 4° and 8°, and preferably 6°, while the second frusto-conical surface 44 may have a second angulation b comprised between 0.5° and 2,5°, and preferably 1.5°.

Preferably, between the sliding surface 48 and the second frusto-conical surface 44 there may be present a draft surface 46 also substantially frusto-conical-shaped and an abutment surface 460, substantially flat and perpendicular with respect to the axis X, whose function will be clearer hereinafter.

Operatively, as illustrated in FIG. 3 to 7, upon inserting the pipe P into the coupling end member 40 the end edge E thereof will come into contact with the draft surface 46, while the first frusto-conical surface 43 will come into contact with the clamps 11 in a single of point of tangency 14'. Advantageously, the draft surface 46, which may have an angulation comprised between 12° and 18° and preferably 15°, may act as means for the abutment and centring of the pipe P. To this end, the diameter of the hole may be lesser than the outer diameter of the pipe P.

The screwing of the ring nut 30 on the threaded coupling end member 40 will promote the radial compression of the clamps 11 on the pipe P, with the ensuing formation of the annular gripping groove G thereon.

Thus, the pipe P and the clamping element 10 will remain mechanically connected in an integral manner. As a matter of fact, subsequently to such mechanical connection the axial translation of the clamping element 10 promoted by the further screwing of the ring nut 30 on the threaded coupling end member 40 will also cause the simultaneous axial translation of the pipe P. In other words, the latter and the clamping element 10 will form the unitary assembly.

Due to the fact that the first frusto-conical surface 43 will come into contact with the clamps 11 in the single point of tangency 14', the radial compression of the clamps 11 will occur with minimum friction.

The further screwing of the ring nut 30 on the threaded coupling end member 40 will promote the contact of the clamps 11 with the sliding surface 48, that will allow the axial sliding of the unitary assembly between the pipe P and the clamping element 10.

Such axial sliding will cause the slipping of the draft surface 46 beyond by the end edge E of the pipe P, so that the end portion F thereof comes into contact with the second frusto-conical surface 44 so as to be radially compressed thereby and define first pneumatic sealing means.

The axial sliding of the unitary assembly between the pipe P and the clamping element 10 promoted by the further screwing of the ring nut 30 on the threaded coupling end member 40 will cease when the end edge E of the pipe P will come into contact with the abutment surface 45.

The axial compression between the latter and the pipe will define second pneumatic sealing means.

More in particular, in a preferred but non-exclusive embodiment, the abutment surface 45 may be defined by an internally tapered annular groove 49 so that the bottom wall 49' thereof has a width L3 smaller than the thickness S of the end edge E of the pipe P.

Thus, the aforementioned pneumatic sealing will operate both on the bottom wall 49' and on the tapering 49".

Advantageously, the sliding surface 48 may be substantially frusto-conical, convergent with respect to the axis X and coaxial with respect to the frusto-conical surface

43, 44.

Furthermore, such sliding surface 48 may suitably have a length LI greater than that L2 of the second frusto-conical surface 44. Thus, there will be created a chamber 41 between the abutment surface 460 and the end 11" of the clamps 11 suitable for the radial expansion of the pipe P.

As a matter of fact, the further screwing of the ring nut 30 on the threaded coupling end member 40 with the end edge E of the pipe P at contact with the abutment surface 45 will cause the radial expansion of the pipe P in the chamber 41.

As the ring nut 30 is progressively screwed onto the threaded coupling end member 40, then, the end portion 11" of the clamps 11 will move between a distal position from the abutment surface 460 and a position proximal thereto, in particular illustrated in FIG. 7.

In such position, the end 11" of the clamps 11 may come into contact with the pipe portion P expanded in the expansion chamber 41, so as to deform it against the abutment surface 460 to define third pneumatic sealing means and a further safety mechanical connection, in particular against water hammer.

As particularly illustrated in FIG. 8, the pipe portion P interposed between the end 11" of the clamps 11 and the abutment surface 460 may be generally flat-shaped, so as to form a true sealed barrier.

Suitably, at the first, second and third pneumatic sealing means mentioned above, the surfaces at mutual contact may have high brightness.

Suitably, the ring nut 30 may include one or more inspection holes 34, so as to allow the operator to visually check the relative position of the ring nut and of the threaded coupling end member 40.

A creaking-like sound, indicating that the ring nut 30 has reached the end-stop, will be heard at the end of the screwing between the ring nut 30 and the threaded end member

40. In light of the above, it is clear that the invention attains the pre-set objectives.

The invention is susceptible to numerous modifications and variants all falling within the inventive concept outlined in the attached claims. Furthermore, all details can be replaced by other technically equivalent elements, and the materials can be different depending on the needs, without departing from the scope of protection defined by the attached claims.