AU680537B2 - Spigot-type coupling - Google Patents

Description

Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

S.

*5 Name of Applicant: Klasse Pty Ltd Actual Inventor: JUSTIN PETER BROWN Address for Service: R K MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia, Australia Invention title: "SPIGOT-TYPE COUPLING" 0s*~ Details of Associated Provisional Application No: Australian Patent Appln No PM 1688 dated 8th October 1993.

The following statement is a full description of this invention, including the best method of performing it known to us.

This invention relates to a coupling, and in particular relates to a spigot type coupling that prevents accidental disengagement of the coupling.

Spigot-type couplings normally comprise a bifurcate spigot which has a pair of projections on each of the portions of the spigot which engage on shoulders of an aperture within which the spigot locates. The bifurcate nature of the spigot allows the two arms of the spigot to resiliently deform inwardly to allow the projections to pass through the aperture. The aperture is normally approximately the same diameter as the diameter of the main body of the spigot.

"In the case of a tubuiar spigot, there is normally a pair of longitudinal slots each of which are located on opposite sides of the tubular spigot portion to form the bifurcate halves. The slots extend from the end of the spigot for a predetermined length so that the two halves resiliently move together. The projections normally comprise a tapered portion that has a horizontal surface which in turn S engages against a planar surface or shoulder which is provided on the side of the aperture which is opposite to the engagement side.

The diameter of the aperture is close to the diameter of the spigot, and is normally a clearance fit to allow ready engagement of the spigot. Any movement of the aperture with respect to the spigot will cause the effective diameter of the hole in plan view to decrease. This in turn causes the wall of the aperture to bear against the halves of the spigot which in turn forces them together, thereby allowing the projections to slip off the shoulder. This allows the coupling to disengage.

Normally, the spigot is attached to a first surface .r member and the aperture is located in a second surface or member. Once the coupling is engaged, any relative movement between the first and second surfaces is applied normally to the spigot with respect to its longitudinal axis. Therefore, no matter how deep the aperture is (that is the amount of aperture wall in contact with the longitudinal length of the spigot) any relative movement between the first and second surfaces will always result in forces being applied normally to the wall of the spigot. If these forces are opplied diametrically across the bifurcate halves, then they will be forced together, thereby allowing either one or more of the projections to disengage from the respective shoulder.

Therefore, it is an object of this invention to overcome the abovementioned problem, and in particular to provide a coupling means that has a support means which prevents normal loads being applied to the spigot.

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In its broadest form, the invention comprises a spigottype coupling having a spigot that is at least bifurcated attached to a first surface with projections at the end of the spigot, an aperture in a second surface through which said spigot locates having shoulder surfaces for abutment with said projections, and support means between said first S and second surfaces arranged such that relative movement between said first and second surfaces causes load to be applied predominantly to said support means so that forces normcl to the longitudinal axis of said spigot are significantly reduced.

The support ineans may comprise a member quite independent of both the spigot and the aperture which is designed to abut against both the first and second surfaces when the spigot-type coupling is engaged. 'Ihis prevents rotation of the second surface with respect to the spigot.

Preferably, the support means may be integrally moulded to either the first or second surface, and in one instance the support means may be integrally formed with the spigot. In this instance, the support means may comprise horizontal surfaces either side of the spigot which abut against Surfaces surrounding the aperture or against the second surface.

-rr -ru LP IIPL~AI~ In this manner, any relative movement between the first and second surfaces cause loads to be applied to the support means which are generally parallel to the longitudinal axis of the spigot, thereby significantly reducing normal forces which cause the bifurcated halves to come together.

In order that the invention be fully understood, a preferred embodiment will now be described, but it should be realised that the invention is not to be confined or restricted to the precise details of this embodiment. This embodiment is illustrated in the accompanying representations in which: Figure 1 shows a side cross-section view of a coupling prior to connection, arLd Figure 2 shows a side cross-section view of a connected coupling.

As seen in the illustration, the spigot-type coupling is associated with a first surface 11 and a second surface 12. In this embodiment, the components of the spigot-type coupling 10 are formed by injection moulding.

The spigot 13 comprises a tubular member having a slot '2 14 which forms two bifurcated halves 15. Towards the end of the spigot, there are provided projections 16 which have horizontal surfaces that extend away from the wall of the spigot 13.

The support means comprise walls 18 which are shown in side view in the illustrations, and the walls 18 have a thickness of approximately 2mm. Each wall 18 has a horizontal portion 19 and a chamfered portion 20 which form an apex 21.

The aperture is formed in a boss 23 which is formed in the second surface 12. The boss 23 is tubular, and at one end is provided with an aperture 24 and around the aperture there are provided a shoulder portion 25. The opening to the boss 26 has a diameter that is significantly larger than the 4 aperture 24, and a tapered portion 27 is used to reduce the diameter of the opening 26 to the diameter of the aperture 24.

Upon engagement of the spigot 13 with the aperture 24, the bifurcate halves 15 move inwardly so as to allow the projections 16 to pass through the aperture and abut against the shoulders 25 such that the coupling 10 is held together.

In ihis position, the walls 18 are arranged such that the apex 21 bears against the tapered portion 27. By careful adjustment of dimensions, and the use of the sufficiently resilient polymeric material, there can be provided an interference fit such that there is a slight compression of material formed in the apex 27. This assists in more rigidly holding the coupling 10 together.

Should there be any relative movement between the first and second surfaces 11 and 12, the loads will be transferred through the walls 18 before there is any appreciable load applied normally to the spigot 13. As can be seen from the above description, this will dramatically decrease the possibility of bifurcate halves being forced together which would result in a release of the coupling The invention will find numerous applications, and will result in a reduced likelihood of disengagement of couplings of this nature.

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Claims (7)

1. A spigot-type coupling comprising, a spigot that is at least bifurcated attached to a first surface with projections at the distal end of the spigot, an aperture in a second surface through which said spigot locates having shoulder surfaces for abutment with said projections, and support means between said first and second surfaces arr;tiged such that relative movement between said first and second surfaces causes any lateral component of the resulting load to be applied predominantly to said support means so that forces normal to the longitudinal axis of said spigot acting on said spigot are "o significantly reduced, said support means comprising a plurality of walls radiating away from said spigot, the plane of each wall substantially parallel to the axis of said spigot.

2. A spigot-type coupling according to claim 1 wherein said support means comprises four walls.

3. A spigot-type coupling according to either claim 1 or 2 wherein said second S* 2Q surface has a tapered portion adjacent said aperture and said walls are shaped to abui -igainst said tapered portion. 00 0* 0

4. A spigot-type coupling according to claim 3 wherein said walls have a S. 00. chamfered portion and a horizontal portion that intersect to form an apex that abuts against said tapered portion.

A spigot-type coupling according to any one of the preceding claims wherein said spigot is tubular.

6. A spigeo.t-type coupling according to any one of the preceding claims wherein said spigot, second surface and support means are moulded from polymeric i vvaterial.

7. A spigot-type coupling substantially as described hereinbef ore and in accordance to and as illustrated in the accompanying drawings. DATED this 21s' day of January 1997 KLASSE PTY LTD By its Patent Attorneys MADDERNS *000 0 0 **ode ABSTRACT This invention relates to a coupling and in particular relates to a spigot-type coupling 10 that prevents accidental disengagement of the coupling. It comprises a spigot 13 that is at least bifurcated and attached to a first surface 11 with projections 16 at the end of the spigot 13, aperture 26 in a second surface 12 through which the spigot 13 locates having shoulder surface 25 for abutment with the projections 16 and support means 18 between the fi-st and second surfaces 11 and 12 arranged so that relative movement between the first and second surfaces 11 and 12 causes load to be applied to the support means 18 so that forces normal to the longitudinal axis of the spigot 13 are significantly reduced. This means accidental disengagement of the spigot 13 from the aperture 26 will be prevented. o *oo *6004