AU775803B2 - Fluid couplings - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicants: DESMOND JOHN BERRY and ROBERT KENNETH MCNAB Invention Title: FLUID COUPLINGS oo oooo o The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 Title Fluid Couplings Field of the Invention This invention relates to fluid couplings especially those for use with flexible pipework.

Background of the Invention 15 There are many types of fluid couplings that essentially comprise flexible tubing, pipework or hose that is press fitted onto a semi-rigid connector usually moulded in plastics. The end fitting of the connector usually has tapered annular retaining rings that the tubing has to be forced over to hold the tubing onto the connector. These connections are used in such simple environments as sprinkler systems in gardens but are also used in more sophisticated environments such as fuel lines or air lines o for air driven machinery and air lines for use in spas and pools.

A problem with this type of coupling concerns the possibility of the internal pressure forcing the flexible tubing off the connector. The internal pressure causes the flexible tubing to expand releasing the interference fit between the locating rings and the tubing and thus pushing the tubing back off the connector. There are a number of ways of reducing the likelihood of this failure including the use of adhesives between the connector and the tubing or, more usually, the provision of an adjustable locking band that is fitted around the exterior of the tubing over the connector. The locking band can be adjusted to clamp the tubing against the connector. Adjustable locking bands F:\akoo\Keep\Pem\P39707.doc 27/09/00 3 do however suffer from problems that they are often incorrectly fitted or in the more sophisticated type that have a threaded adjustment they do not provide uniform pressure around the whole periphery of the tubing. In tight and confined spaces the locking bands can also be difficult to fit or remove for disassembly.

It is these problems that have brought about the present invention.

Summary of the Invention According to the present invention there is provided a fluid coupling for attachment to a free end of a flexible tubing, the fluid coupling comprising: a connector having at least one end with at least one radially projecting rib, the end being adapted to be a force fit within the free end of the tubing so that the rib causes a radially outward expansion of the tubing; and oeoo a locking ring having an inextensible band coupled to resilient gripping means, the resilient gripping means being a sliding fit on the tubing, the inextensible oooo band being an interference fit on the expanded portion of the tubing so as to clamp the tubing between the inextensible band and the at least one rib thereby 25 preventing axial separation of the tubing from the e eo "°connector.

••go Description of the Drawings An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic side elevational view of a fluid coupling in accordance with the invention; Figure 2 is another cross sectional view of the coupling; and Figure 3 is a perspective view of part of a \\melb_files\home$\shirleyp\specis\P39707 Amended.doc 4 locking ring that forms part of the coupling.

Description of the Preferred Embodiment As shown in the accompanying drawings a fluid coupling 10 comprises a length of plastics tubing 11 having a free end 12 that is arranged to be a forced fit on a semi rigid plastics connector 13 which is in the form of, for example, a T-piece having an inlet end 14, outlet end and T-junction 16. The plastics connector 13 has an internal throughway 17 and the connector of the inlet and outlet ends 14 or 15 are provided with a pair of spaced apart annular ribs 20 and 21. The annular ribs 20, 21 have 15 an outer profile that tapers outwardly towards the center of the connector to provide a leading taper that enables the free end 12 of the tubing 11 to be forced over the ribs 21 so that the ribs force the wall of the tubing to flex outwardly and bite into the interior surface of the tubing to reduce the likelihood of the tubing being forced off the connector by the internal fluid pressure.

A locking ring 30 is positioned on the. exterior of the assembly to hold the adjacent portion of the tubing against the connector. The locking ring 30 is shown in Figure 3 and essentially comprises a plastics moulding in the form of an inextensible annular band 31 from which a plurality of equally spaced teeth 32 project axially. Each tooth terminates in a downwardly turned edge defining a sharp arcuate rim 33. The teeth 32 have a degree of inherent flexibility that allows them to flex radially outwardly.

To assemble the coupling the locking ring 30 is first slid onto the connector 13. The internal diameter of the locking band 31 is greater than the maximum diameter of the connector 13 so it is easy to slide the locking ring onto the connector which is then located towards the centre \\MELBOI\homeS\akhoo\Keep\Perm\P39707.doc 27/09/00 5 of the connector. The free end 12 of the tubing 11 is then forced over the end 14 of the connector to assume the position as shown in Figure 1. The locking ring 30 is then pushed back over the tubing. The internal diameter of the band 31 of the locking ring 30 is slightly greater than the tube but the internal diameter defined by the teeth 32 is of smaller diameter so that as the ring 30 is pulled back over the tube it stops where the band 31 contacts the portion of the tube that has been expanded outwardly by the ribs 20, 21. The interference between the expanded exterior of the tubing 11 and the internal surface of the band 31 causes a wedging action holding the locking ring in position on the connector. In this position as shown in Figure 1 the teeth 32 push into the outer surface of the 15 tubing.

When the coupling becomes subject to internal pressure that might cause the tubing to be forced off the connector 13, the teeth 32 embedded in the tubing cause the locking ring 30 to be dragged back with the tubing squeezing the tubing between band 31 and rib 21. The locking ring is firmly held onto the tubing and the interaction of the teeth 32 with ribs 20, 21 of the connector effectively prevent separation of the components o* 25 and considerably improve the capacity of the fluid coupling to resist high internal pressures.

In the embodiment described above the fluid coupling is used in a pool/spa pump in the air line of that assembly where a flexible plastics tubing is used to supply air to a water jet assembly. The semi-rigid plastics connector 13 couples the air line to the jet assembly. In this environment there is a need for a simple and reliable coupling that will not separate in a high pressure environment. It is however understood that the coupling can be used in many other situations such as garden watering, irrigation installations.

\\M4ELBO1\homeS\akhoo\Keep\Peri\P39707.doe 27/09/00 6 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims (5)

1. A fluid coupling for attachment to a free end of a flexible tubing, the fluid coupling comprising: a connector having at least one end with at least one radially projecting rib, the end being adapted to be a force fit within the free end of the tubing so that the rib causes a radially outward expansion of the tubing; and a locking ring having an inextensible band coupled to resilient gripping means, the resilient gripping means being a sliding fit on the tubing, the inextensible band being an interference fit on the expanded portion of the tubing so as to clamp the tubing between the inextensible band and the at least one rib thereby preventing axial separation of the tubing from the connector.

2. A fluid coupling as claimed in either claim 1, wherein the resilient gripping means of the locking ring 20 comprises a plurality of spaced teeth extending behind the inextensible band, the teeth having radially inward rib projecting edges that engage and grip into the outer S: surface of the tubing.

3. A fluid coupling as claimed in any one of the preceding claims, wherein the connector has a pair of spaced apart ribs, each rib having an inclined leading face to facilitate entry of the connector into the end of the tubing.

4. A fluid coupling as claimed in any one of the preceding claims, wherein the locking ring is moulded in plastics.

5. A fluid coupling substantially as herein described with reference to the accompanying drawings. \\melb_files\home$\shirleyp\specis\P39707 Amended.doc -8 Dated this 25th day of June 2004 ROBERT KENNETH MCNAB and DESMOND JOHN BERRY By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\9hirleyp\spec ia\P39707 Amendeddoc