NZ195771A - Coupling for flexible hose pipe:hose wedged on to sleeve by nut - Google Patents

Description

195771 200149 Patents Form No. 5 Number 195771 and 200149 PATENTS ACT 1953 Dated May 5, 1981 and March 26, 1982 COMPLETE SPECIFICATION IMPROVEMENTS IN OR RELATING TO PIPE COUPLINGS ALBERT FREDERICK HANSEN a New Zealand citizen of Punga Grove Road, Whangarei, New Zealand do hereby declare the invention for which I/w« pray that a Patent may be granted to me/usx and the method by which it is to be performed, to be particularly described in and by the following statement: 1 195771 200149 My present invention relates to a device for coupling pipes, and in partiuclar pipes formed of a substance known as alkathene or polythene.

Such pipes generally have a minimum diameter of approximately 15rrtm and are utilized for permanent or semi-permanent installations for the transmission of fluids such as water in, for example, irrigation systems or the like. Alkathene and polythene pipes generally have a hard wall and are semi-rigid, and require particular techniques for coupling which are quite distinct from methods of coupling soft walled pipes such as for instance garden hoses and the like. Couplings intended for the coupling of such soft walled pipes are unsatisfactory for the coupling of hardwalled pipes.

In broad terms my invention may be said to comprise a pipe coupling including a tubular portion over which the end of a pipe to be coupled may be engaged, the said tubular portion including an annular boss having an external screw thread carrying a nut having an internal screw thread of a substantially constant pitch whereby the nut as rotatable on the boss so as to be movable onto the exterior of the end of a pipe engaged on the said tubular portion to clamp the pipe onto the said tubular portion, the said nut comprising two 2 195771 200149 concentric bores of different diameters, the bore of lesser diameter being complementarily screw threaded so as to be engagable with said screw threaded annular boss and the bore of greater diameter being engagable with the outside surface of the end of the said pipe.

The bore of the coupling nut which is of greater diameter may be of as substantially constant cross section or may be tapered outwardly from the interior of the nut.

Preferably the said tubular portion of the coupling terminates in a nose tapered with an increasing diameter from the leading edge of the nose to assist in maintaining the end of the pipe on the coupling and to enable the pipe to be introduced onto the coupling with relative ease.

The coupling may include a plurality of annular ridges on said tubular portion to further assist the coupling to grip the piping. 3 195771 200149 With couplings of the invention the end of a pipe can be fully engaged onto the coupling, as will be further described, and the nut can then be rotated so as to be moved onto the exterior of the end of the pipe so that one portion of the nut engages the exterior of the piping and another portion of tine nut engages the annular boss portion of the coupling.

To assist further understanding of the present invention a preferred embodiment thereof which comprises the best method of performing the invention known to me will now be described with reference to the accompanying drawings, wherein: Fig. 1 is an external side view of a preferred embodiment coupling, and Fig. 2 is a longitudinal sectional view along the line II-II of Fig. 4 195771 20014 The^ preferred embodiment coupling shown in the drawings is of the type suitable for joining one length of hard walled pipe to another length of such pipe. However, it is envisaged and considered obvious that the coupling can be readily adapted e.g. by having one end only formed as shown in the drawings with the other end being formed into an appropriate male or female fitting, to couple the end of a pipe to some device or apparatus. It is also envisaged that the coupling may be readily formed into a bend, a tee or any desired shape.

The preferred embodiment coupling is - preferably formed from an engineering plastics material and preferably includes a central section 1 which is preferably of greater thickness than the remainder of the coupling and which provides a gripping portion which has a polygonal outer surface such as 195771 200149 that shown, to aid holding of the coupling during fitting and use. Other shapes of the outside wall comprising the gripping portion of the central section 1 of the coupling can be utilised as required. The said wall could be provided with a series of longitudinal ribs or other indentations or protrusions to enable the body of' the coupling to be gripped and held. The provison of a central section 1 is preferred since it provides the coupling with a length so that if an in-service pipe should fracture, the body of the coupling will be of sufficient length to allow the ends of the pipe to be trimmed with the central section 1 of the coupling substantially compensating for the portion of the piping which is removed during the trimming process.

Extending outwardly from each side of the central section 1 is an annular boss 2, the external walls of which are each provided with a screw thread 2a.

Each boss 2 extends into a tubular portion 3 of reduced diameter, over which the end of a pipe to be coupled can be engaged, and which terminates in a nose 4 bevelled as at 5 so as to have an increasing diameter from its leading edge, to form a taper of, for example, approximately 15 degrees. Other angles of bevel may be used as desired with the essential requirement being to allow the end of the piping to be coupled to be easily slid over the nose 4. The 6 195771 200149 bevelled portion preferably terminates in an annular ridge such as that indicated at 5a. A single additional ridge 6 of a buttress shape is provided and this has a steeper bevel than the bevel 5.

The coupling can also include one or more rows of barbs, indicated at 3a in Fig. 1, spaced around the tubular portion 3, whose purpose is to prevent rotation of piping on the coupling during movement of the securing nut on to the end of a pipe to be coupled, as will be further described hereinafter. In addition it will be appreciated that the provision of these barbs 3a will assist the pipe in being gripped by and held on the coupling.

A bore 11 extends through the central section 1, bosses 2 and tubular portions 3 of the coupling as shown.

A nut 8 is carried on each of the bosses 2 (only one such nut 8 is shown in the drawings. 7 195771 200149 The interior of each coupling nut is formed into two concentric bores of different diameters. The bore 9 is of a lesser diameter and is screw threaded so that the nut 8 is engagable on the screw threaded annular boss portion 2a_ and is rotatable thereon. As can be seen from the drawings the nut 8 is positioned on the boss 2 so that the smaller bore 9 will be adjacent the central section 1. The bore 10, which is of greater diameter, faces outwardly from the central section 1, and may be of a constant diameter with a step being formed between it and the bore 9 (not shown in the drawings), or may be tapered outwardly from the interior of the nut as shown, so that its diameter reduces to the diameter of the lesser diameter bore 9. The screw threads of the bores 9 and 10 of the nut 8 are of the same hand and of a substantially constant pitch.

To retain each nut 8 on the coupling, a split washer 12, which may be formed of a plastics material or other material as desired, can be placed over each tubular portion 3 (shown in Fig 2 only). The washer 12 has an external diameter greater than the diameter of the lesser diameter bore 9 but less than the diameter of the greater diameter bore 10. When it is desired to remove a nut 8 from the coupling the washer 12 must first be removed from the tubular section 3 and the nut 8 can be slid over the nose 4.

N.Z. PATENT OFFICE -5 OCT 1984 RECEIVED 8 195771 200149 To connect the end of a section of pipe, such as that indicated at 15 to, for example, one end of a coupling of the invention, the nose of the coupling is entered into the interior of the end of the pipe and the pipe is pushed home onto the tubular portion 3 as earlier described, preferably until the end of the pipe 15 abuts against the shoulder 2b of the boss 2 or against the washer 12 if this is used. This ensures a positive indication of the correct placement of the end of the pipe 15 on the coupling. The nut 8 is then screwed towards the nose 4 and the forward portion 8a of the nut 8 will be guided over the exterior of the pipe 15 and will tend to clamp the end of the pipe 15 onto the tubular portion 3. The nut 8 will tend to cut or form its own thread in the end of the pipe as it is advanced.

The thread on the greater diameter bore 10 is preferably of a buttress form but can be of a standard form.

The coupling shown in the drawings has such abutress thread, having a taper of approximately 7% degrees from the leading edge to the back 21. The thread angles may vary slightly but preferably range from 90 degrees vertical on the ''leading edge and 50 degrees on the trailing edge too 100 degrees negative on the leading edge and 45 degrees on the trailing edge. The most preferred thread angles are in the 90 and 100 degree negative range on the leading edge and 45 degrees on the trailing edge. i 9 195771 20014 The coupling nut shown in cross-section in Figs. 4 and 5 also include a buttress thread as shown.

It has been found that a buttress or vertical "shark tooth" thread provides an excellent grip on the exterior surface of the end of the pipe, because as it is pushed onto, for example, a polythene pipe, the displaced polythene forms behind the thread. Thus the nut has a greater ability to withstand tension at the joint than, for example, a nut having a British Standard Pipe Thread where the displaced polythene travels ahead of the thread.

Claims (7)

10 195771 WHAT I CLAIM IS: 200149

1. A pipe coupling including a tubular portion over which the end of a pipe to be coupled may be engaged, the said tubular portion including an annular boss having an external screw thread carrying a nut having an internal screw thread, on which boss the nut is rotatable so as to be movable onto the exterior of the end of a pipe engaged on the said tubular portion to clamp the pipe onto the said tubular portion, the said nut comprising two concentric bores of different diameters, the bore of lesser diameter being complementarily screw threaded so as to be engagable with the said screw threaded annular boss, and the bore of greater diameter being screw threaded so as to be engagable with the outside surface of the said pipe, the screw threads of the said lesser and greater diameter bores being of the same hand and of a substantially constant pitch.

2. A pipe coupling as claimed in claim 1 wherein the said bore of greater diameter is of a substantially constant cross section.

3. A pipe coupling as claimed in claim 1 wherein the said bore of greater diameter is tapered outwardly from the interior of the nut. N.Z. PATENT OFFICE ^CE.'Vi-D 11 195771 200149

4. A pipe coupling as claimed in any one of the preceding claims wherein the screw thread of the said bore of greater diameter is of a buttress form.

5. A pipe coupling as claimed in any one of the preceding claims wherein the said tubular portion terminates in a nose tapered with an increasing diameter from the leading edge of the nose.

6. A pipe coupling as claimed in any one of the preceding claims wherein the coupling is of a type comprising a central section providing a gripping portion, from each end of which extends a said tubular portion and a said annular boss carrying a said coupling nut, the coupling being of a type suitable for joining one length of pipe to another length of pipe.

7. A pipe coupling substantially as described as illustrated herein. WEST/WALKER, Mc^ABE Per: ATTORNEYS FOR THE APPLICANT