AUSTRALIA Patents Act 1990 Innovation Patent Specification Title: Nozzle plate filter tank assembly Applicant(s): Waterco Limited Inventor(s): Pradeep Kumar Tandon Agent: © COTTERS Patent & Trade Mark Attorneys The following is a full description of the invention which sets forth the best method known to the applicant of performing it.
2 Nozzle plate filter tank assembly Field of the Invention The present invention relates to a filter tank assembly. In particular, the present invention 5 relates to a nozzle plate filter tank assembly for use with swimming pool or spa filter tanks. However, it will be appreciated by those skilled in the art that the filter tank assembly can be applied to other water treatment applications, and in particular commercial and industrial applications. Background of the Invention 10 Water filter tanks are used to filter water for numerous residential, commercial and industrial applications. One particular application requiring water filtration concerns swimming pools and spas. In swimming pool and spa applications, the filtering system typically includes a tank or is storage vessel which is filled with sand or another filtration medium. A multiport valve containing both inlet and outlet ports is located on either the top or side of the storage vessel. During filtration, the inlet port receives water from the pool and releases the water to be filtered into the filtration medium. The pressure within the storage vessel forces the water to pass through the sand in which the water is filtered on the basis of depth filtration. 20 During this process, dirt is driven through the filter bed and becomes trapped in minute spaces between the particles of sand. The filtered water then passes through a number of nozzles which are mounted on a nozzle plate which is located near the base of the tank. After passing through the nozzles, the 25 filtered water enters a nozzle-plate chamber. An outlet port directs water from the nozzle plate chamber to a multi port valve, and the water is subsequently returned to the pool. Water filter tanks were previously manufactured from steel or metallic alloys, and fabricated through a welding process. However, steel tanks are subject to chemical and/or mechanical 30 wear, which may reduce the lifespan of the tank. The weld lines are known areas of weakness in welded steel tanks. In addition, steel tanks are often relatively heavy, and hence difficult to transport and install. Fabrication of steel tanks is also costly and material 3 intensive. In contrast, some filter tanks are now being manufactured from fibreglass. The fibreglass is applied through a filament winding process under controlled tension to create a seamless 5 one-piece vessel exhibiting refined consistency and superior quality. Advantageously, there are no welds or seams. In addition, there is no need to use special tank linings which can corrode or electrolyse. Fibreglass vessels have superior mechanical and chemical resistance when compared to steel. In addition, fibreglass tanks do not rust or corrode and are able to withstand many types of water treatment chemicals. 10 The nozzle plate is generally manufactured from a circular disc of fibreglass with resin, which is located within the tank. The nozzle plate is secured to the tank by a lamination process. The nozzle plate is located towards the base of the tank, near where the diameter of the tank starts to decrease. 15 A problem with using a nozzle plate within a fibreglass tank is that the fibreglass tank wall is less rigid than comparable steel tanks. Whilst the fibreglass provides increased durability and strength, during filtering or backwashing pressure changes occur within the tank. These pressure changes result in expansion and contraction of the tank wall. The filtering cycle of a 20 swimming pool typically results in the expansion and contraction occurring on a cyclical basis. The strain occurring at the joint located between the tank and the nozzle plate can ultimately result in failure of that joint, requiring costly repairs or replacement of the tank. 25 Object of the Invention It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages, or to provide a useful alternative. 30 Summary of the Invention In a first aspect, the present invention provides a filter tank assembly comprising: a filter tank; a filtration unit located in the filter tank, the filtration unit having a cover and an adjacent base portion, the cover and base portion defining a chamber; 4 one or more filters associated with the cover, the filters providing fluid communication between the filter tank and the chamber; and an outlet port located within the chamber, the outlet port adapted to direct fluid out of the filter assembly. 5 In a second aspect, the present invention provides a filter lateral assembly comprising: a filter nozzle having a proximal end and threaded distal end, a fluid inlet located adjacent to the proximal end, and a fluid outlet located adjacent to the distal end; a filter lateral having a receptacle adapted to receive the fluid inlet of the filter nozzle, io the distal end of the filter nozzle projecting through an aperture formed in the filter lateral; a base member having a base plate located adjacent to the aperture and a hollow tubular projection extending away from the base plate, the hollow tubular projection being adapted to receive the distal end of the filter nozzle; and a retaining ring having an internally threaded hole adapted to receive the threaded is distal end of the filter nozzle adjacent to a trailing end of the hollow tubular projection. The retaining ring preferably has a frustoconical shaped leading edge adapted to be inserted into the trailing end of the hollow tubular projection, further wherein the trailing end of the hollow tubular projection has one or more longitudinally extending channels. The retaining 20 ring preferably also includes one or more longitudinally extending ribs adapted to be received in the longitudinally extending channels. In a third aspect, the present invention provides a method of securing a filter lateral assembly to a nozzle plate, the method including the steps of: 25 inserting a distal threaded end of a filter nozzle into a hole formed in the nozzle plate, the distal end being threadedly connected to a retaining ring; rotating the filter nozzle within the retaining ring and within a tubular projection extending away from a body of the lateral assembly, thereby driving a tapered leading edge of the retaining ring along the threaded end of the filter nozzle towards the tubular 30 projection, wherein engagement of the retaining ring with the tubular projection radially expands the tubular projection which frictionally engages an outer wall of the hole.
5 The base portion preferably has a shape which is generally complimentary to a base of the filter tank. The base portion of the chamber is preferably unsecured relative to the base of the filter 5 tank. The filter tank is preferably manufactured from fibreglass and the nozzle plate chamber is manufactured from fibreglass and resin. 10 The outlet port preferably extends through an aperture formed in the cover into the filter tank and passes through a side wall or upper region of the filter tank. The retaining ring preferably has a frustoconical shaped leading edge adapted to be inserted into the trailing end of the hollow tubular projection. 15 The trailing end of the hollow tubular projection preferably has one or more longitudinally extending channels. The retaining ring preferably includes one or more longitudinally extending ribs adapted to 20 be received in the longitudinally extending channels. The proximal end of the filter nozzle preferably includes an engagement formation. The engagement formation is preferably a hexagonal headed bolt head. 25 The proximal end of the filter nozzle preferably includes a shoulder which is engageable with a surface formed on the filter lateral, whereby the shoulder clamps the lateral against the base member. 30 Brief Description of the Drawings A preferred embodiment of the invention will now be described by way of specific example with reference to the accompanying drawings, in which: Fig. 1 is a partial sectioned side view of a prior art nozzle plate filter; 6 Fig. 2 is a detail of a joint between the nozzle plate and the tank wall in the filter of Fig. 1; Fig. 3 is a top view of a nozzle plate unit according to a preferred embodiment; Fig. 4 is a sectional side view depicting the nozzle plate unit of Fig. 3 in a filter tank; 5 Fig. 5 is an exploded perspective view showing a nozzle; Fig. 6 is a side assembled view of the nozzle of Fig. 5; Fig. 7 is a side cross-sectional view depicting a portion of a nozzle plate; Fig. 8 depicts the nozzle of Fig. 5 mounted on the plate of Fig. 7; Figs. 9 to 12 schematically depict the manufacture steps of securing the nozzle plate to io a filter tank; and Figs 13. To 15 depict further manufacture steps of assembling the nozzle plate chamber. Detailed Description of the Preferred Embodiments is A prior art nozzle plate filter tank 10 is disclosed in Figs. 1 and 2. As shown in the detail of Fig. 2, the nozzle plate 12 is bonded to the wall 18 of the filter tank 10, and the nozzle plate 12 includes a plurality of nozzles 14. An embodiment of a filter assembly 30 according to the invention is depicted in Figs. 3 and 20 4. The nozzle plate assembly 30 is manufactured as an enclosed nozzle plate unit 29 having an interior nozzle plate chamber 32. The nozzle plate assembly 30 includes an upper nozzle plate cover or surface 31 and an adjacent base portion 33. The nozzle plate assembly 30 is seated within the base of the filter tank 10. The nozzle 25 plate assembly 30 is independent of, and not attached to the outer wall of the filter tank 10. As such, when the filter tank 10 expands or contracts due to changes in internal pressure or other environmental factors, any change in volume of the filter tank 10 has limited effect on the structural integrity of the nozzle plate chamber 32. 30 As depicted in Fig. 4, the base portion 33 of the nozzle plate unit 29 has a generally complimentary shape relative to the inner wall of the filter tank 10. In the embodiment depicted in the drawings, the base portion 33 is generally bowl shaped. Expansion or contraction of the filter tank 10 has minimal effect on the nozzle plate chamber 32, as the nozzle plate chamber 32 and the filter tank are not directly connected to each other. As 7 such, when the outer wall of the filter tank 10 expands, the structural expansion does not significantly strain the nozzle plate chamber 32. The base portion 33 wraps over the upper nozzle plate surface 31 to provide an overlapping join. 5 As depicted in Fig. 3, the nozzle plate 12 includes an inspection opening 20, permitting a user to access the cavity or space 34 located within the nozzle plate chamber 32 for maintenance or servicing purposes. A further inspection opening is provided in the outer wall of the filter tank 10, such that either the contents of the filter tank 10 or the nozzle plate chamber 32 can be readily accessed. 10 The manufacture of the nozzle plate chamber 32 will now be described. The process is depicted in Figs. 9 to 15. The bottom portion of the filter tank 10 is manufactured first. When the base portion of the filter tank 10 has been fabricated, a wax layer is applied to the is bottom, inside wall of the filter tank 10. The wax acts as a separator between the filter tank 10 and the nozzle plate chamber 32. The base portion 33 of the nozzle plate chamber 32 is made from hand laid fibreglass and polyester resin. This is laid directly onto the wax layer. 20 The nozzle plate 12 and outlet port 40 are then added, as depicted in Fig. 11. As shown in Figs. 13 and 14, initially an additional skirt 17 of fibreglass extends upwardly beyond the upper surface of the nozzle plate 12. The skirt 17 is then folded downwardly, and radially inwardly and secured to the upper surface of the nozzle plate 12 with polyester resin. 25 An upper portion 37 of the tank 10 is then manufactured. The upper and lower portions 33, 37 of the tank 10 are subsequently joined together. Fibreglass is then wound around the tank 10 to provide increased strength. As such, upon completion of the tank 10, the nozzle plate chamber 32 is permanently located within the filter tank 10. 30 The outlet port 40 extends through an aperture formed in the nozzle plate surface into the filter tank 10 body where the filtration medium is located, and then passes through a side wall of the filter tank 10. During a filtration cycle, unfiltered water enters the filter tank 10, usually at the top of the tank 10. The water passes through the filtration medium which 8 may be sand, or some other medium which is located within the filter tank 10. The filtration medium assists to remove particulate matter from the water. The filtered water then passes through the nozzles 14 into the cavity 34 located within the nozzle plate chamber 32. The filtered water then enters the outlet port 40 which passes through a hole formed in a 5 central region of the nozzle plate 12. The outlet port 40 returns the filtered water to the swimming pool or spa, and extends through a hole formed in either the side wall or upper region of the filter tank 10. The flow direction can be reversed during back-flushing to clean the filtration medium. 10 An exploded perspective view of a nozzle 14 is depicted in Fig. 5. The nozzle 14 includes a stem or filter nozzle 50. The nozzle 14 also includes a tapered filtration head or lateral 52, a base plate 54 and a retaining ring 56. Referring to Fig. 6, the components of the nozzle 14 are shown assembled. Fig. 7 schematically depicts the nozzle plate 12, and Fig. 8 depicts is the nozzle 14 and plate 12 assembled. The assembly and installation of the nozzle 14 will now be described. Initially, the nozzle 14 is assembled as shown in Fig. 6. In order to produce this assembly, a distal end 51 of the filter nozzle 50 is inserted into the lateral 52 from above. The underside of shoulder 58 of 20 the filter nozzle 50 abuts against a corresponding surface or shoulder 60 located within the lateral 52. This prevents the lateral 52 from being removed upwardly. The distal end 51 of the filter nozzle 50 is externally threaded, and this distal end 51 is received in the hole 62 formed within the base plate 54. The hole 62 is not threaded. 25 The retaining ring 56 has an internally formed annular shoulder (not shown). This generally corresponds in size to the annular rib 64 which is formed on the distal end 51 of the nozzle 50. Accordingly, the retaining ring 56 snaps onto the distal end of the nozzle 50, but is movable axially, toward the proximal end 72 of the filter nozzle 50. The annular rib 64 and 30 the shoulder located within the retaining ring 56 hold the nozzle 14 components together, such that none of the individual components can easily become separated or lost. The male threaded stem of the nozzle 50 corresponds with a female threaded hole 69 located within the retaining ring 56.
9 The proximal end 72 of the filter nozzle 50 has a plurality of fluid flow apertures 53. The apertures provide entry into the hollow centre of the nozzle 50, and the fluid is able to exit from an opening at the distal end 51 of the nozzle 50. 5 When the nozzle 14 is assembled, water is able to pass through slots 61 formed in the lateral 52. The slots 61 mechanically filter the water. This prevents the filtration medium, such as sand from passing through the slots into the nozzle plate chamber 32. 10 As best seen in Fig. 5, the retaining ring 56 has a plurality of longitudinally extending projections 66. The projections correspond with longitudinally extending slots 67 formed on the tubular extension 55 located on the underside of the base plate 54. In addition, the leading end of the retaining ring 56 has a generally frustoconical, inwardly tapering portion 57 which is smaller in diameter than an end of the tubular extension 55. 15 The tubular extension 55 of the base plate and the retaining ring 56 are initially of a similar outer diameter. This can be seen in Fig. 6. The tubular extension 55 and retaining ring 56 are inserted into the hole 70 formed in the nozzle plate 12. The proximal end 72 of the nozzle 50 includes a tool engagement formation 74, which in the embodiment shown in the 20 drawings is a hexagonal headed bolt 74. By rotating the bolt head 74 clockwise, the threaded nozzle 50 also rotates within the tubular extension 55. The end of the threaded nozzle 50 engages the threaded hole 69 within the retaining ring 56. Continued rotation of the bolt head 74 clamps the lateral 52 between the 25 base plate 54 and the shoulder 58. The base plate 54 includes projections or lugs 77 which can be used to stop the base plate 54 from rotating while the bolt head 74 is rotated. The distal end of the of the nozzle 50 is connected to retaining ring 56 on account of the threaded connection. Accordingly, the retaining ring 56 is pulled axially towards the nozzle 30 plate 12. The engagement between the longitudinally extending projections 66 and the longitudinally extending slots 67 prevents the retaining ring 56 from rotating with the thread, thereby forcing it to advance axially. As the bolt head 74 is wound further, the tapering portion 57 is pulled further within the 10 tubular extension 55. As shown in Fig. 5, the tubular extension 55 has grooves or channels 59. The channels enable the tubular extension to expand outwardly as the tapering portion 57 moves axially. This increases the diameter of the tubular extension 55, thereby securing the lateral 14 to the nozzle plate 12, because the expanded outer diameter interferes with 5 the hole formed in the nozzle plate 12. The fastening system described above enables the nozzle 14 to be secured to the nozzle plate 12 without any access to the underside of the nozzle plate 12. This is advantageous, as it negates the need to separately locate any portion of the nozzle 14, such as a nut, on the io underside of the nozzle plate 14. Advantageously, when internal pressure is applied within the filter tank 10, the filter tank 10expands on its own with minimal strain applied on the nozzle plate 12. is Advantageously, the filter assembly 30 allows the nozzle plate 12 to be flexible, while generally preventing the collapse of the nozzle plate 12. This is because the direct impact of cyclic pressure from the outer tank is not transferred to the inner chamber. Although the invention has been described with reference to specific examples, it will be 20 appreciated by those skilled in the art that the invention may be embodied in many other forms.