Improved quick-connect and disconnect pipe-joint fitting

Abstract: The object of the present invention is an improved quick-connect and disconnect pipe-joint fitting, in that the shape of the elastic tabs (2b) that lock the inserted pipe into the joint are shaped in a new and original fashion, in respect of their past design, so that the aforementioned tabs, even when made of plastic, can effectively exert a gripping action, even on plastic pipes.

Description: The object of the present industrial patent application is an improved quick-connect and disconnect pipe-joint fitting. The applicant is also the owner of Industrial Italian Patent N. 208921 (& WO-A-8705087) granted on 28/5/88 following an application registered on 13/2/86, the object of which is a quick-connect and disconnect fitting for water system piping. One advantage, among many, of this fitting is that it can be quickly and easily unscrewed from the pipe to which it is attached, unlike all previous models which were difficult to disconnect to the extent that, in similar circumstances, the pipe was cut close to the joint, and if the joint was to be re-used, the end of the pipe that remained in the joint had to be removed, an elaborate and troublesome task. The invention that is the object of Italian Patent N. 208921 (& WO-A-8705087) consists of a joint with a hollow cylindrical body. The hole in the body where the pipe is inserted is of a larger bore than the external diameter of the pipe, so that it can house a sleeve with an internal diameter that exactly matches that of the exterior of the tube. There is a ring of flexible tabs at the end of the sleeve, that are created by deep diametric cuts at regular intervals in the front end of the sleeve. The interior of the cylindrical cavity that houses the aforementioned sleeve and in which it can move has a number of tightening ribs, and its front end is a ring like truncated cone-shaped shoulder. This shoulder connects the aforementioned cavity to an intermediate section of the tube with a smaller diameter, which in turn ends in a ring-shaped step, beyond which there is the tube whose diameter is precisely the same as the internal diameter of the pipe, and which projects from the other end of the body of the joint; the opposite end to that in which the pipe is inserted. It should be pointed out that truncated cone-shaped shoulder at the end of the section of tube in which the aforementioned sleeve is housed and can move, has its narrow end facing the sleeve, and thus towards the entrance to the joint. Therefore, when the sleeve is pushed forward as far as it will go, all the flexible tabs are stretched apart by the truncated cone-shaped surface against which the aforementioned tabs are pressed. When the sleeve is extracted from its housing, the aforementioned tightening ribs in the housing exert an action which is completely the opposite of that of the truncated cone-shaped shoulder, and exert a centripetal pressure on the external backs of the tabs, causing the tabs to bend towards the interior, and the tabs tend to lock together towards the centre thus permitting the complete extraction of the sleeve when there is no pipe present which would otherwise obstruct the tabs from bending sufficiently towards the centre to permit the sleeve to be removed from the joint. On the contrary, in the last of the two above cases, the teeth on the internal side of the flexible tabs bite into the external surface of the pipe with ever increasing force, thus preventing the pipe from being removed while the system is operating, even when subject to a great deal of tractive force. The pipe is, however, easy and quick to disconnect, when the sleeve is held in one hand in a fully forward position, and the pipe is pulled back by the other. In this case, the pipe is no longer externally locked in place by the teeth on the tabs, which are now held in an open position by the truncated cone-shaped surface against which they are pressed while the sleeve is held pressed in a fully forward position. During the use of the aforementioned quick connect and disconnect joint, it has however been found that the biting action of the teeth on the internal side of the aforementioned flexible tabs is not always sufficient to completely ensure that the pipe does not come out of the joint, especially when the aforementioned sleeve is moulded in plastic and the pipe is also made of plastic. In these circumstances, it has been found that the teeth tend to slide on the pipe, which can thus, when force is applied, progressively work its way free from the joint. In order to increase the efficiency and reliability of the locking action of the flexible tabs on the section of pipe inserted in the joint, an improved version of this joint according to the present invention has been introduced. This improved version has specially shaped tabs that, instead of having gripping teeth as the old version does, have internal edges that are angled towards the centre thus virtually forming a section of cone whose axis is the same as the lengthwise axis of the joint. In other words, in this new model, the tube is no longer held in several places distributed along the same circumference, but by a lot of lenghtwise sections lying on a single truncated cone-shaped surface. To be more precise, in this new improved joint each flexible tab has a straight external edge that diverges towards the exterior, and a straight internal edge that diverges towards the interior, thus the width of these tabs gradually increases the further it is from the end they are attached to the sleeve. The internal wall of the cavity housing the tabs and in which they can move axially is shaped like a truncated cone, with the narrow end towards the entrance to the joint, so that when the sleeve is extracted all the tabs are progressively and simultaneously bent towards the centre, consequently gradually locking into place a section of pipe that is as long as the internal edges of the tabs. For greater clarity, the description of the invention that follows makes reference to the attached sheet of drawings, which is solely to illustrate and is not limiting, in which: Figure 1 is a half view /half cross-section of the improved joint according to the invention, in which the sleeve is shown in a fully forward position with the tabs fully stretched apart; Figure 2 is a half view / half cross-section of the improved joint according to the invention, in which the sleeve is shown in a slightly pulled back position with the tabs locked around the pipe. With reference to the aforementioned Figures, the improved joint includes a cylindrical body (1) inside which there are three co-axial tubular sections of a decreasing diameter starting from the pipe insertion side. The first section (1a) forms the housing of a sleeve (2) with an external flange (2a) that strikes against the body (1). The first section (1a) has an internal truncated cone-shaped wall whose narrow end faces towards the rear, and thus the diameter of its transverse section increases the further it is from the entrance hole; the front end of the aforementioned section (1a) has a truncated cone-shaped shoulder (3), which is more conical than the section and functions as a connection to the intermediate tubular section (1b) of the cylindrical body. The aforementioned sleeve (2) has a ring-shaped series of flexible tabs (2b) which are internally angled towards the centre and externally angled towards the exterior. This means that the cylindrical entrance to the sleeve (2) is of a diameter equal to that of the pipe, and forms the wide end of a truncated cone-shaped tube with an ever decreasing diameter that is defined and formed by the internal sides of the aforementioned flexible tabs. When a pipe is introduced into the joint, these tabs stretch apart elastically until their external edges hit the truncated cone-shaped internal surface of their housing (1a). There is a pointed extremity at the front end of the flexible tabs (2b) which strikes against the projecting truncated cone-shaped shoulder (3), which tends to stretch the tabs (2b) apart each time the sleeve (2) is pushed forward. There is a groove (4) in the intermediate tubular section (1b) that houses a sealing ring (5), and there is a screw thread (6) on the exterior of the last tubular section (1c).

Claims: A quick-connect and disconnect pipe-joint fitting, of the type that includes a cylindrical body (1), in the interior of which there are three co-axial tubular sections of decreasing diameters, the largest of which (1a) faces the entrance to the joint and forms the housing of a sleeve (2), and has a truncated cone-shaped internal wall with a truncated cone-shaped shoulder (3) at its front end said wall and said shoulder tapering with their narrow ends towards the entrance; said sleeve (2) having a ring-shaped series of flexible tabs (2b) without gripping teeth, which tabs are internally angled towards the centre and externally angled towards the exterior so that the width of the tabs gradually increases the further it is from the end they are attached to the sleeve and so that the entrance to the sleeve (2) is circular in section and of a constant diameter, and then extends into the form of a truncated cone-shaped tube with a decreasing diameter that is defined and formed by the internal sides of the aforementioned tabs (2b); and the aforementioned tabs (2b) having pointed extremities that strike against the projecting truncated cone-shaped shoulder (3) each time the sleeve (2) is pushed forward.

Inventors: GOBBI GIANFRANCO, GOBBI, GIANFRANCO
Applicants: GOBBI GIANFRANCO, GOBBI, GIANFRANCO
Application year: 1991
Main classification: F16L37
IPC codes: F16L21, F16L37