AU2011101730B4 - Closure - Google Patents

Abstract

A closure (10) including a spanning element (12) to span an opening and sealingly engage structure (20) defining the opening. A threaded element (13) is threadlingly engageable with the 5 structure (20) and one or more further elements (11) fastened to the spanning element (12) capture the threaded element (13) between the spanning element (12) and the further element (11) such that the threaded element (13) is axially retained, and is rotatable, relative to the spanning element (12). The threaded element (13) is rotatable to drive the spanning element (12) from said sealing engagement without rotation of the spanning element (12).

Description

WADESON AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Invention title: Closure The following statement is a full description of this invention, including the best method of performing it known to us: lA Closure Field of the invention The invention relates to closures. The invention will be described with reference to a swimming pool filter, although the 5 invention has broader application. Background of the invention A typical lid for a soft drink bottle includes an internally threaded cylindrical wall spanned by a more or less planar ceiling. A disc of elastomeric material spans the internal surface of the ceiling. To close the bottle the threads of the lid are engaged with external threads 0 about the neck of the bottle, and as the lid is tightened the outer periphery of the elastomeric disc is compressed between an annular end face of the neck and the ceiling. This arrangement is referred to as a compression seal. Compression seals can be problematic in larger applications. A relatively large amount of force is required to create a satisfactory seal, and the seal can tend to bind so as to resist .5 unscrewing. This can make it difficult to open the closure and can damage the seal. A swimming pool filter is an example of a vessel requiring a relatively large reversible closure to resist the internal operating pressures or vacuum yet permit access to, and removal of, the filter media. In the past swimming pool filters have incorporated compression seals, but rather than a 20 threaded engagement, like a soft drink lid, a locking ring has been used. One such arrangement includes a respective lip encircling each of the mating surfaces of the lid and the vessel of the filter housing. Each lip includes a conical outer surface converging in a direction away from the mating surface. The locking ring takes the form of a band of strip material the ends of which carry complementary threaded arrangements by which the band may be tightened not unlike a 25 traditional hose clamp. The strip of material is formed so as to cooperate with each of the tapered surfaces whereby as the band is tightened it acts on the surfaces to axially drive the lid and the vessel to compress an elastomeric seal, eg. an O-ring, carried therebetween.

2 This locking ring arrangement is an advance over a 'soft drink lid construction' in that rotation of the lid relative to the vessel is not required to remove the lid, however it is not without its problems. It has been found that this style of lid can still stick in place and be difficult to remove. The locking ring has traditionally been formed of cast aluminium, steel or stainless 5 steel to have enough strength to create sufficient compression to seal the lid under the pressures created by the pool pump and filtration system. These locking rings are expensive to manufacture and often large, heavy and difficult for a homeowner to remove and refit during regular maintenance. Moreover the shape of the conical lips has been found to produce stress concentrations leading to cracking in the long term. 0 Some existing swimming pool lids incorporate a "piston seal" in place of a compression seal. "Piston seal" describes the sealing engagement of a cylindrical surface. A typical piston seal is formed by a resilient member in the form of an O-ring, carried in an outward facing groove about the cylindrical exterior of a piston, engaging the cylindrical interior of a complementary bore. Alternatively the O-ring might be carried by the bore to engage the 5 cylindrical exterior of the piston. O-ringless piston seals are also possible. In the context of a swimming pool filter, a piston seal is seen as an advance over a compression seal because less force is required to create a satisfactory watertight seal such that the above "heavy duty" locking ring is not required. An existing swimming pool filter includes a vessel with an externally threaded tubular 20 opening of about 500mm in diameter. The closure includes an element to span the opening. This spanning element carries a cylindrical skirt about its outer periphery. The cylindrical skirt is sized to be received within the cylindrical interior of the vessel's opening and carries an O-ring in an outwardly facing groove to sealingly engage the cylindrical internal surface. A threaded element, referred to as a locking collar, takes the form of an internally threaded plastic ring and 25 is cooperable with the vessel's external threads. The locking collar includes shaped upper portions to overlie portions of the spanning element. As such the collar serves to prevent the spanning element being driven from the vessel by any internal pressure. The spanning element can be difficult to remove because the O-ring forming the piston seal is tightly engaged with the internal surface and/or can become caked in debris. The 30 spanning element can also be held in place by vacuum within the vessel.

3 In a previous attempt to address this problem the spanning element and the collar were snap-locked together during manufacturing assembly such that when the collar is unwound it drives the spanning element from sealing engagement with the vessel. Experience has shown that this approach is problematic. In the context of such large diameter lids, snap-locking parts 5 together requires special tooling and presses and/or special production processes, and then in use the lid and collar have been found to bind so that as the collar is unwound the spanning element, and the O-ring, is rotated thus stretching and wearing the O-ring. It is an object of the invention to provide an improved closure, or at least to provide an alternative for those concerned with closures. 0 Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. Summary of the invention .5 One aspect of the invention provides a closure including a spanning element to span an opening and sealingly engage structure defining the opening; a threaded element threadlingly engageable with the structure; one or more further elements fastened to the spanning element to capture the threaded 20 element between the spanning element and the further element such that the threaded element is axially retained, and is rotatable, relative to the spanning element; whereby the threaded element is rotatable to drive the spanning element from said sealing engagement without rotation of the spanning element. The further elements are preferably handles. Desirably there may be two handles. 25 Preferably each handle includes two portions positioned to overlie and thereby capture the threaded element.

4 Preferably the threaded element is an internally threaded ring. Optionally, the sealing engagement is a piston seal. Optionally the spanning element carries a resilient sealing member to form said sealing engagement. 5 Another aspect of the invention provides a swimming pool filter including a vessel having an opening; and the closure closing the opening. Another aspect of the invention provides a method of forming a closure, the closure including 10 a spanning element to span an opening and sealingly engage structure defining the opening; a threaded element threadlingly engageable with the structure; and one or more further elements; the method including 15 fastening the further elements to the spanning element to capture the threaded element between the spanning element and the further elements such that the threaded element is axially retained, and is rotatable, relative to the spanning element; whereby the threaded element is rotatable to drive the spanning element from said sealing engagement without rotation of the spanning element. 20 Brief description of the drawings / figures Figure 1 is a perspective view of a swimming pool filter in accordance with an embodiment of the invention; Figure 2 is a front view of the filter of figure 1; and 5 Figure 3 is an axial cross section view through a portion of the closure of the filter of figure 1. Detailed description of the embodiments Figures 1 and 2 show a filter I in accordance with a preferred embodiment of the 5 invention. The filter 1 includes a closure 10 and a vessel 20. The vessel 20 is an upwardly open cup like structure and includes an external thread 23 about an upper portion of its cylindrical wall 24. The open upper end of the vessel 20 is closed by the closure 10 to define a sealed pressure vessel. A pump (not shown) is plumbed to flow ports 21, 22 of the vessel 20 to pump water to be 0 filtered through the filter 1. As such the interior of the vessel is in use exposed to positive and/or negative pressure. A gauge 30 is mounted to the closure 10 to provide an indication of the internal pressure within the filter 1. The closure 10 includes a domed element 12 to span the opening of the vessel, a threaded element in the form of collar 13 and a pair of handles 11. Each of the element 12, collar 13 and 5 handles 11 is a separately formed injection molded component. The element 12 is a thin walled dome structure and includes a short cylindrical skirt 122 downwardly depending about its outer periphery. The skirt 122 is dimensioned to be received within the cylindrical wall 24 of the vessel 20. An outer lower edge of the skirt 122 includes a chamfer 124 to provide a lead in to assist with insertion of the skirt 122 through the opening of 20 the vessel 20. A circumferential groove 121 encircles the skirt 122. The groove 121 is positioned above and adjacent to chamfer 124 and opens outwardly. The groove 121 carries a resilient sealing member in the form of an O-ring 121B. The O-ring 121B has a circular cross section. The groove 121 has a rectangular cross section dimensioned so that a portion of the O-ring's toroidal 25 exterior projects beyond the cylindrical exterior of the skirt 122 to bear against and sealingly engage the cylindrical interior 25 of the vessel 20. The closure 10 thus forms a piston seal with the vessel 20.

6 Upwards of the groove 121, a short radial flange 120 encircles and extends outwardly from the skirt 122. The flange 120 is positioned to abut the upper free edge of the wall 24 of the vessel 20 to provide a stop to limit the insertion of the skirt 122 into the vessel 20. The collar 13 is a ring shaped structure including a cylindrical wall 131 carrying an 5 internal thread 133. The internal thread 133 is cooperable with the external thread 23 of the vessel 20. The upper end of the collar 13 carries a short inwardly directed radial flange 132. The flange 132 overlies the flange 120 of the element 12 so that engaging threads 133 with the threads 23 of the vessel and tightening the collar 13 serves to clamp the flange 120 between the wall 24 of the vessel 20 and the flange 132. 10 The collar 13 includes six vertically ribbed gripping portions 134 equispaced about its exterior. The ribbed texture of the portions 134 provide purchase for a user to rotate the collar 13. Turning to the upper portions of figure 3, the element 12 carries four upwardly projecting bosses 123. The bosses 123 are arranged in a rectangular array centred on the dome of the 15 element 12. The bosses 123 provide attachment points by which the handles 11 are attached to the element 12. The handles 11 perform a dual function. They function as handles (ie. provide convenient gripping points) and capture the collar 13 such that the collar 13 is axially retained but is rotatable relative to the element 12. As such the collar 13 is free to rotate relative to the 20 element 12 but cannot be removed from the element 12. Each handle 11 includes an arcuate central gripping portion 111. Each end of each handle 11 includes a mounting portion 112 and a nose portion 110 (see figure 3). An underside of each mounting portion 112 includes an internal recess to receive a respective boss 123, and the top of each mounting portion 112 includes a counter bored screw 25 hole through which a screw (not shown) engages the threaded internal bore of the boss 123 to fasten the handle 11 to the element 12. Of course other fastening arrangements are possible. It is also contemplated that the handles could be glued or sonically welded in place. Threaded fasteners are preferred as they are reversible to permit replacement of the handles in the event of damage.

7 Each nose portion 110 projects downwardly and radially outwardly from the mounting portion 112 to overlie the flange 132 of the collar 13. The nose portion 110 thus captures the collar 13 so that it is axially retained relative to the element 12. The nose 110 is axially spaced from the flange 132 to permit free rotation of the collar 5 13. In this embodiment the vertical gap is about 6.5mm. To close the filter I (eg. after servicing filter cartridges carried within the vessel 20) the closure 10 is placed in its approximate position. The cylindrical wall 131 of the collar 13 and the chamfer 124 of the element 12 assist with finding a preliminary alignment. The collar 13 can then be rotated so that its threads 133 engage with the threads of the vessel 20 to drive the 0 closure 10 into its assembled position. To open the filter 1, a user simply rotates the collar 13 in the opposite direction. As the threaded engagement with the vessel 20 unwinds, the collar 13 is lifted until it abuts the nose portions 110 of the handles 11. With continued rotation of the collar 13 the threaded engagement serves to axially drive handles 11 and element 12 to lift the closure 10. In particular the O-ring 5 1211B carried in groove 121 is lifted clear of the vessel 20. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 20

Claims (5)

1. A closure including a spanning element to span an opening and sealingly engage structure defining the opening; 5 a threaded element threadingly engageable with the structure; one or more handles fastened to the spanning element to capture the threaded element between the spanning element and the handle(s) such that the threaded element is axially retained, and is rotatable, relative to the spanning element; whereby the threaded element is rotatable to drive the spanning element from 10 said sealing engagement without rotation of the spanning element.

2. The closure of claim 1 including threaded fasteners so fastening the handle(s).

3. The closure of claim 1 or 2 wherein the threaded element is an internally threaded ring.

4. A swimming pool filter including 15 a vessel having an opening; and the closure of any one of claims 1 to 3 closing the opening.

5. A method of forming a closure, the closure including 9 a spanning element to span an opening and sealingly engage structure defining the opening; a threaded element threadingly engageable with the structure; and one or more handles; 5 the method including fastening the handle(s) to the spanning element to capture the threaded element between the spanning element and the handle(s) such that the threaded element is axially retained, and is rotatable, relative to the spanning element; whereby the threaded element is rotatable to drive the spanning element from 10 said sealing engagement without rotation of the spanning element.