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Field of the Invention

This invention concerns a connector fitting for fluid transport tubes, for example, water. Prior Art

As is known there are connector fittings comprising a coupling and a ring nut fitted around a tube and both connected by screwing. The ring nut has an internal serrated ring to grip the tube and to tighten around it by screwing said ring nut onto the coupling. At one of its ends this coupling has at least one opening for inserting the tube to be coupled and can be provided on the other end with a closing wall if this tube is to be used as the final length of a fluid transport duct. The screwing and tightening operation of the screw around the coupling may be rather long and laborious, in particular for the tightening phase of the serrated ring around the surface of the tube and furthermore, the sealing gaskets which are usually housed between the coupling and the ring nut are subjected to considerable stress. Object and Summary of the Invention

An objective of this invention is to provide a fitting for tubes transporting fluids than allows screwing of the ring nut to the coupling and tightening of the serrated ring around the tube which is rapid and easy to carry out.

This objective is reached by this invention through the use of a connector fitting for tubes transporting fluids comprising a coupling suitable for engaging with a ring nut and provided at the front with an opening for inserting a tube; positioned inside said ring nut is at least a first ring provided with internal teeth for gripping the external surface of said tube and characterised in that said ring nut consists of a first internal threaded part and a second part provided with means fitted to tighten this first ring around the tube; inside this ring nut and fitted around the tube is a second ring provided with a first ring shaped component fitted to push at least one sealing gasket into a cylindrical housing starting from the opening of said coupling and a second ring shaped component in contact with the edge of the opening of said coupling; such first ring shaped component and such second ring shaped component are provided with means suitable for allowing a certain longitudinal sliding movement of one with respect to the other. Brief Description of the Drawings

Further characteristics and advantages of this invention will be better understood from the following description, considered as indicative and not limiting and referred to the enclosed

- Fig. 1 shows a lateral elevation and sectional view of a tube on which a connector fitting for fluid transport tubes is applied comprising a coupling and ring nut which can be screwed to said coupling;

- Fig. 2 shows a lateral elevation and sectional view of the connector fitting in Fig. 1 , with relative ring nut partially screwed onto the coupling;

- Fig. 3 shows a lateral elevation and sectional view of the connector

fitting in Figs. 1 and 2 comprising internally a first ring provided with teeth for connecting to the tube and a second ring provided with a first ring shaped component and a second ring shaped component fitted to push a seal into a cylindrical housing machined in said coupling; - Fig. 4 shows a lateral elevation and exploded view of said first ring provided with teeth for connecting to the tube and said second ring shown in the previous figures;

- Fig. 5 shows a lateral elevation view of said first and second ring in Fig. 4 connected one to the other by means of a pin; - Fig. 6 shows a front view according to the line Vl-Vl in Fig. 4 of said second internal ring of this fitting.

- Fig. 7 shows a further lateral elevation view according to line VII-VII in Fig. 6 of said second ring;

- Fig. 8 shows a further front view according to line Vl-Vl in Fig. 4 of said second internal ring which has received some changes in plan; and

- Fig. 9 shows a lateral elevation view according to line IX/IX in Fig. 8 of said second internal ring.

Detailed Description of the Invention

With reference to said enclosed drawings and in particular to Fig. 1 , the reference 1 shows a tube for transporting fluids, for example water. Looking at the drawing, the left end of said tube 1 , is inserted into a coupling 2, which, in this example, is closed at one end and therefore stops the flow of the fluid inside tube 1. Evidently this coupling 2 could be open at both ends and therefore allow coupling at either of its ends of two adjacent fluid transport

tubes. Said coupling 2 therefore comprises on at least one end a round opening 202 and a length with external threading 102 starting from said round opening 202 inside which a cylindrical housing 302 has been provided. An O- ring seal 3 has been fitted around tube 1 so as to be inserted and come into contact with the bottom of said round housing 302. Number 4 shows a ring nut which comprises a first part threaded on the inside 104 having a constant diameter and larger than the diameter of the external threaded length 102 of the coupling 2. The internally threaded part 104, level with the end facing towards said coupling 2 comprises an opening 204 and is provided to engage with said externally threaded portion 102 of coupling 2. This ring nut 4 also comprises a second part 304 with an external truncated cone shape surface 404 and an internal surface made up of three truncated cone lengths 504 having substantially the same inclination, with diameter and internal section decreasing as it moves away from the internal threaded length 104 and forming a triple cone. Between said internally threaded part 204 and said second part 304 an annular contact surface 704 is provided. Inside said ring nut 4 is shown a first ring 5, visible also in Fig. 4, comprising externally a collar 105 and a number of wedges 205, the external surface_Me_a.cJbJs_macle-up-Qf- two truncated cone lengths 305, having substantially the same inclination, with diameter and internal section decreasing as it moves away from the collar 105 forming a double cone. Ring 5 is also made up of a longitudinal opening 405 provided to allow it to be tightened around tube 1 and, on the internal surface, raised gripping teeth 505. This longitudinal opening 405 has two steps 605 level with the edge of the collar.

A second ring 6 is fitted around the tube 1 and inside the ring nut 4, which is made up of two different annular components 106 and 206, visible in Figs 5, 6 and 7. The first annular component 106 comprises, towards the second annular component 206, a collar 306, provided to come into contact with said annular surface 704 present between said internally threaded part 104 and said second part 304 of the ring nut 4. Some grooves 406, in this case three, have been machined in said first annular component 106 level with the collar 306; a plate 506, connected to the second annular component 206 by means of a specially shaped leg 706 is free to move longitudinally in each of the grooves, without the possibility of exiting from them. In collar 306 in fact, and level with each of said grooves 406, there is a longitudinal opening 606 for said leg 706 to slide in: this longitudinal opening 606 has a narrower passage width than the relative groove 406 and plate 506, see Fig. 7. The front surface of the collar 306 of the first annular component 106 has a pin 806 provided to link up to the two steps 605 provided in the longitudinal opening 405 of the first ring 5. Comparing Fig. 4 and Fig. 5 this pin linked to steps 605 can be seen and the second annular component 206 in contact with the surface of the collar 306 of the first annular comp^nejrvMΩfi-Qf_ttιe-second-riFig 6, thanks to the sliding of the plates 506 with relative legs 706 along the grooves 406 and the longitudinal openings 606. Protruding teeth 906, in this case three, fixed in a ring-shaped groove 604 provided on the ring nut 4 between the first internally threaded part 104 and the second part 304 with triple taper are provided on the lateral surface of the collar 306 of the first annular component 106.

Fig. 2 shows a partially tightened position of the ring nut 4 on the coupling 2, with the O-ring seal 3 partially inserted in the cylindrical housing 302 of said coupling 2. By screwing the internally threaded part 104 of the ring nut 4 onto the externally threaded length 102 of the coupling 2, the first annular component 106 of the second ring 6 has the task of pushing said O- ring seal 3 towards the bottom of said cylindrical housing 302, by means of the contact of the rounded stop surface 704 of the ring nut 4 against the collar 306 of said first annular component 106, and to sustain the operating pressure force. The second annular component 206 of said second ring 6 on the other hand, has the task, always by screwing the ring nut 4 on the coupling 2, to move into contact, by means of the legs 706, against the front surface of the round shaped opening 202 of the coupling 2 and therefore to cause the stop of the forward movement of the same annular component 206 and ring 5 provided with locking teeth 505. Figs 8 and 9 show the second internal ring 6 of this connector fitting, which has variations to the work plan: the pin 806', provided to link up to the two steps 605 provided in the longitudinal opening 405 in the first ring 5, is divided into two symmetric parts and is positione^Jgy^jjaαtb-Qne-of-the-leg& 706 and the protruding teeth 906', fixed in the round shaped groove 604 provided in the ring nut 4 between the first internally threaded part 104 and the second part 304 with triple taper, are always to be found on the collar 306 but with a shorter length and an increased width compared to the previously described protruding teeth 906.

Therefore, in order to screw this connector fitting to tube 1 , first of all

place in position the coupling 2, ring nut 4, with the first ring 5 provided with gripping teeth 505 and the second ring 6 made up of two annular components

106 and 206, and the O-ring seal 2 on the tube 1 ; move ring nut 4 and O-ring

, 3 towards the coupling and then screw said ring nut 4 by hand onto said coupling 2.

By continuing to tighten the internally threaded part 104 of the ring nut 4 onto the external threaded part 102 of the coupling 2, see Fig. 3, the O-ring seal 3 reaches the bottom of the cylindrical housing 302 of said coupling 2. The ring 3, from the moment the second annular component 206 is, by means of the legs 706, in contact with the edge of the circular opening 202 of the coupling 2, can no longer move forward and consequently the external surfaces 305 of the double taper wedges 205 are obliged to slide along the three truncated conical lengths 504 of the ring nut 4. This gradual sliding without excessive stress thanks to said double and triple taper result in a diametric closing of the first ring 3, enabled by the longitudinal opening 405 provided in it, that, together with the relative teeth 505 grips the external surface of the tube 1. The two annular components 106 and 206 of the second ring 6 cannot be separated from each other, but. whe_ceasJ:he_r-inq-3-slides^ along the internal surfaces 504 of the ring nut 4, the first annular component 106 with respect to the second annular component 206, slides by means of the plates 506 which move inside the relative grooves 406 un the opposite direction to the ring 3, enabling said O-ring seal 3 to reach the bottom of the cylindrical housing 302 of the coupling 2.

Should it be required, for greater safety, final tightening of this

connector fitting can be carried out by turning the ring nut 4 about half a turn using a wrench. At this point the connector fitting can be used at the maximum operating pressure.

The raised teeth 906 on the lateral surface of the collar 306 of the first annular component 106 inserted in the annular grooving 604 inside the ring nut 4, prevent accidental unscrewing of the ring 6 of said ring nut 4 during normal transport operations of this connector fitting.