AU2004203858B2 - Injection device - Google Patents

Description

AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: INJECTION DEVICE Applicant: SPA ELECTRICS PTY LTD The following statement is a full description of this invention, including the best method of performing it known to me: 1 2 INJECTION DEVICE The present invention relates to an injection device for injecting a fluid of one viscosity into another fluid of greater viscosity. The present invention has been 5 developed in relation to the injection of air into water, in particular for use in spas and pools and it will be convenient to describe the invention in relation to that application. However, it should be appreciated that the invention is envisaged to have a wider application for use in other areas in which injection of one less viscous liquid is made into another liquid of greater viscosity. 10 It is common in spas and pools to inject air through the base or walls thereof to create a turbulent body of water or to create a gentle bubbling effect for general enjoyment. In relation to spas, the turbulence or gentle bubbling is often associated with a massage effect on the spa occupants for relaxation and/or 15 muscle recuperation. Present injectors generally inject a single stream of air, or a mixture of water and air, through the wall or base of a pool or spa. The injection is therefore highly concentrated, and therefore does not spread evenly throughout the body 20 of liquid in the spa or pool. To attend to this, injectors or jets have been developed by the applicant which have a greater spread of air or air/water mixture, although early versions of these were not satisfactorily developed, as they tended to create air bubbles of large volume which increase the water turbulence to unacceptable levels. This is because even though the air 25 released from such injectors is spread across a wider area, the bubbles nevertheless tend to merge or gather together, so that while the initial air injection may comprise a plurality of small and independent bubbles, the bubbles tend to merge or gather together away from the injector, reducing the number of bubbles and increasing the volume or size of the bubbles that 30 remain. The merger or gathering together of bubbles continues as the bubbles rise through the body of water. Accordingly, if the depth of the body of water is sufficient, the bubbles tend to merge into a single bubble of very large volume, which erupts at the surface of the body of water causing great turbulence. W:\Julie\Andrew\Speci\Injection Device.doc 3 The applicant has recognised that merging of the bubbles seems to occur because of differences in pressure on either side of the bubbles being released, so that the bubbles tend to shift, or are pushed, toward regions of lower pressure as they rise within the water. In experiments conducted by the 5 applicant, air was released from about the full periphery of a bubbler, and the bubbles formed immediately shifted toward the centre of the periphery, merging at a point above the bubbler. The point of merging could be varied by changing the input pressure, so that the rate at which the bubbles merged slowed and by doing that, the bubbles were more likely to remain separated for their full rise to 10 the water surface, however it was not a particularly practical solution, as it imposed undesirable limitations on the air pressure that could be employed, and it limited the use of such bubblers to spas or pools of relatively shallow depth of about 1 m or less. 15 It is an object of the present invention to overcome or at least alleviate one or more disadvantages associated with the prior art and associated with bubblers developed by the applicant. It is a further and particular object of the invention, to provide a bubbler, in which merger of bubbles emitted from the bubbler is substantially reduced, or in a highly preferred arrangement entirely eliminated. 20 According to the present invention there is provided an injection device for injection of gas into liquid, including a chamber which communicates with a gas supply, said chamber being defined partly by a gas distribution plate having a plurality of gas outlets, said 25 plate including a peripheral edge and a broad outer facing upper surface bounded by said edge, said outlets are formed at both said peripheral edge and inwardly of said edge through said plate, wherein said outlets are distributed such that, upon egress of gas through said outlets and into a liquid to form gas bubbles, said liquid is drawn from beyond 30 said peripheral edge over said upper surface of said plate to regions internally of said edge and said liquid drawn internally rises with said gas bubbles to an upper surface of said liquid due to frictional engagement between said gas bubbles and said liquid. W:\Julie\Andrew\Speci\Injection Device.doc 4 By drawing liquid over the upper surface of the plate to regions internally of the peripheral edge, the difference in liquid pressure between the liquid internally and externally of the peripheral edge, is reduced, or equalised, so that individual 5 bubbles formed by gas released from the peripheral edge rise substantially vertically, rather than shifting inwardly and merging with other bubbles released either through the upper surface of the plate or at other positions about the peripheral edge. 10 The injection device described above advantageously maintains the bubbles separated from each other, or if merging occurs, then it occurs on a much reduced scale than previously. Further, the invention has facilitated the production of highly desirable very fine bubbles that create low turbulence and which rise to the water surface generally separately. While such bubbles are 15 desirable for pool and spa installations, they are also envisaged to be desirable for applications of the invention in other fields, such as for aeration in aquariums and pools containing marine plant and fish life, or for mixing purposes, say for chemical mixing, or for continuous mixing of liquid bodies. 20 It will be convenient to describe the invention hereinafter with reference to its use as a bubbler for the production of air bubbles in bodies of water. It should be appreciated however, that the range of other applications discussed above, as well as other applications suitable for the present invention but not discussed above, are all within the scope of the present invention. 25 It should also be appreciated that references throughout this specification as to the substantially vertical rise of bubbles discharged from the device, assume that the liquid body into which the bubbles are discharged, is substantially still, or is turbulent to the extent which is caused by the normal operation of pool or 30 spa jets or other relevant equipment. In a preferred arrangement of the injection device of the invention, the plate is generally circular and defines a generally circular peripheral edge. The plate could however be otherwise shaped, such as square, rectangular or oval, W:Julie\Andrew\Speci\Injection Device.doc 5 although a circular plate is preferred as it facilitates more uniform pressures about the periphery of the plate and across the upper plate surface internal of the periphery. 5 In a preferred arrangement, the air outlets of the peripheral edge are provided in spaced-apart groups which are separated from each other by edge regions absent of outlets and which are substantially or completely closed against egress or discharge of air therefrom. The outlet groups can include any number of air outlets and this is somewhat dependent on the size of the injection device. 10 In an injection device having a circular plate of about 200 mm diameter, each outlet group can have about four outlets. The closed regions of the peripheral edge are closed to facilitate unimpeded flow of water from beyond the peripheral edge of the device, to regions of the 15 plate surface internally of the edge. The closed regions therefore do not include air outlets, so that air being discharged through the peripheral edge is discharged at sections of the edge which are adjacent or separated by the closed sections. 20 The chamber of the device can be formed in any suitable manner and preferably the device has a plate and a base which are connectable together and which form the chamber upon their connection. Preferably the base extends to the peripheral edge of the plate and seals with the plate at that edge, so that air which is discharged through the edge is discharged only through the 25 outlets formed at the peripheral edge. Preferably those outlets are formed in the plate at the edge thereof, although the outlets could be formed in the base, or in each of the plate and base. In one preferred form of the invention, the outlets are formed in the edge of the plate and are formed as elongate slots which extend radially inwardly, and which can converge slightly inwardly as the 30 slots extend radially toward the centre of the plate. The base of the device preferably includes a connector for connecting to a supply of air and while that connector can be positioned anywhere suitable, in the preferred form of the device, it is positioned centrally of the base. The form W:\Julie\Andrew\Speci\Injection Device.doc 6 of connector can also be any suitable form, but the preferred form is a circular flange that extends rearwardly of the base for receipt within one end of a pipe connector. 5 The chamber also can have any suitable shape, although the chamber shape can have an effect on the discharge of air through the outlets of the device. In the preferred form, the chamber is circular and has a generally planar or flat base and the plate is domed, so that the chamber has maximum height or depth at the center and minimum height or depth at the edges. With the connector 10 centred in the base, the air supplied to the chamber enters at the centre thereof and flows to the peripheral edge. Pressure within the chamber therefore is dependent on the number, positioning and size of outlets provided in the plate, internally of the peripheral edge, as well as the rate of change in depth of the chamber from the centre to the edge. 15 It is to be appreciated that the general discussion of operation of the device above, relates to operation following initial start-up of the device. At start-up, the chamber of the device will likely be full of water, which enters the chamber in the absence of air being forced into the chamber under pressure. Upon 20 commencement of air injection into the chamber, water is flushed from the chamber and thereafter, air discharge through the device commences. The closed edge sections can be closed against discharge of air by any suitable arrangement. In one arrangement, the chamber is configured for delivery of air 25 to the spaced-apart outlets, but not to the closed regions between those outlets. In this arrangement, the closed regions of the edge periphery between the outlet groups are not necessarily sealed closed (although that is preferred), but rather, do not provide for discharge of air because air is prevented from entering the closed regions for discharge therefrom, or alternatively, is directed away 30 from the closed regions. For example, the chamber can form a plurality of delivery chutes, which accept air from a pressurised supply and which extend to each outlet group. The chutes may be formed as a tubular conduits, such as circular or square and may diverge from centrally of the device to the peripheral edge. The chutes may be formed by walls that extend between and in W:Julie\Andrew\Speci\njection Device.doc 7 engagement with internally facing surfaces of both the plate and the base connected thereto, or may be otherwise formed as appropriate. In one arrangement, the walls extend from the plate to the base and are accepted into a groove or channel formed in the base, or upstanding therefrom. The walls 5 could alternatively extend from the base for acceptance into a groove or channel formed in or upstanding from the plate. Still alternatively, the chute arrangement may be formed separately from the plate and base and may be inserted into a chamber or space defined therebetween during assembly of the injection device. 10 The outlets provided internally of the peripheral edge can be provided in any suitable manner, however in the preferred arrangement, a circular pattern of outlets is provided. In the arrangement in which the plate is circular, the internal openings can be disposed in a ring formed at a constant radius about the centre 15 of the plate. The plate also preferably includes generally linear radiating lines of outlets which extend from a position approaching the centre of the plate to a position adjacent the peripheral edge. If the plate includes a circular pattern of outlets 20 about the centre of the plate, then the outlets can extend generally radially to a position adjacent the circular pattern of outlets. The radial outlets do not have to be aligned along a true radial line, but can be slightly offset from radial if necessary. 25 The lines of outlets can be spaced equally about the surface of the plate, particularly if the plate is circular, or they can be positioned otherwise if the shape of the plate is other than circular. The outlet lines and the peripheral edge effectively define the upper surface of the plate into segments. In a circular plate, the outlet lines may extend to the centre of the plate, or if a 30 circular pattern of outlets is provided, to those outlets. Adjacent segments are therefore defined and in use, air curtains of bubbles are formed by air discharged through the outlet lines. As the bubbles rise, water from above the upper surface of the plate but within the segments is drawn upwardly with the bubbles, and that removal of water from each segment causes water to be W:Uulie\Andrew\Speci\lnjection Device.doc 8 drawn across the upper surface of the plate to replace the displaced water. It is drawn from across the peripheral edge, preferably across the closed sections of that edge. This arrangement advantageously allows substantial bubble discharge from the device, maintaining the bubbles separate as they rise to the 5 surface by the replenishment of water to within the segments as water within the segments is drawn upwardly with the bubbles. The attached drawings show an example embodiment of the invention of the foregoing kind. The particularity of those drawings and the associated 10 description does not supersede the generality of the preceding broad description of the invention. Figure 1 is a perspective view of the upper surface of a plate for use in the invention. 15 Figure 2 is a perspective view of the inside surface of the plate of Figure 1. Figure 3 is a plan view of the upper surface of the plate of Figure 1. 20 Figure 4 is a perspective view of the inside surface of a base for connection to the plate of Figures 1 to 3. Figure 5 is a perspective view of the underneath surface of the base of Figure 4. 25 Figures 1 and 2 show perspective views of a plate 10, taken from above and below the plate, while Figure 3 shows a plan view of the plate taken from above. The plate 10 is formed for connection to a base which is disclosed and discussed in relation to subsequent figures. 30 The plate 10 is circular and defines an edge periphery 11. The plate 10 is formed with a slight concave profile, to define an outer curved or domed convex surface 12 while the inner surface 13 shown in Figure 2, has a concave profile. The plate 10 is formed of a plastic material or a metal, or ceramic material. W:\Julie\Andrew\Speci\njection Device.doc 9 The edge periphery 11 of the plate 10 includes a plurality of groups 14, of outlets 15. The outlets 15 are each open at the outermost radial edge 16 of the periphery 11 and extend radially rearwardly from the edge 16. As shown, each of the outlets 15 converges slightly towards the rear or radially inner end 17 5 thereof (see Figure 3). The plate 10 further includes a plurality of outlet columns 18 which extend rearwardly from the edge periphery 11, generally radially. The columns 18 are not absolutely radial in their positioning, but, as shown in Figure 3, they are 10 slightly offset from a true radial of the plate 10. The plate 10 further includes a central circular pattern of outlets 19 (see Figure 3), and the outlet columns 18 terminate just prior to the pattern of outlets 19. 15 Referring to Figure 2, extending from the inner surface 13, is a plurality of wall portions 20 which include a pair of converging side walls 21 and an end wall 22. The respective walls 21 and 22 define a segment 23 which, in an assembled form of the plate 10 with a suitable base, is isolated from pressurised air that is fed into the device for discharge through the respective outlets 15, 18 and 19. 20 Figure 2 shows the positioning of the outlet columns 18 relative to the side walls 21, and it can be seen from Figure 2, that each column 18 extends closely adjacent one of the side walls 21 of each segment 23. This view also illustrates why the outlet columns 18 are not truly radial, but instead are slightly offset or 25 skewed from true radial, as it is the side walls 21 which are truly radially aligned and the columns 18 extend alongside the side walls 21. Disposed within three of the segments 23, are screw fastener openings 24 which are arranged for receipt of suitable screw fasteners that screw into the 30 base of the device. The openings 24 are countersunk so that the heads of the screw fasteners are located below the outer surface 12 of the plate 10 when the plate is fastened to a base. WAJulie\Andrew\Speci\Injection Device.doc 10 The Figures 4 and 5 show a base 30 for connection to the plate 10 from two perspective views, the first showing the internal surface of the base which faces the inner surface 13 of the plate 10 when the plate 10 and base 30 are assembled together, while Figure 5 shows the external or underneath surface of 5 the base 30. Referring to Figure 4, the base 30 includes a peripheral edge 31 and an inner surface 32 and in the form illustrated, the inner surface 32 is generally planar. The base 30 is formed as a circle, of a diameter equal to the diameter of the 10 plate 10, so that the respective peripheral edges 11 and 31 overly each other in an assembled form of the plate 10 and the base 30. Likewise, the inner surface 32 includes a plurality of segments 33 which are defined by inner and outer walls 34 and 35, which define a groove 36 15 therebetween. The groove 36 is of a width suitable to accept the free edge 37 of the walls 21, 22 (see Figure 2) of the plate 10. The groove 36 is of a shallow depth, but is sufficient to accept the free edge 37 and to securely locate the respective walls 21 and 22. As will become from later discussion, when the plate 10 is assembled to the base 30, the acceptance of the free edges 37 in 20 the grooves 36 is such as to exclude passage of air into the segments 23 so that the air which is discharged through the plate 10, is discharged through the outlets 15, 18 and 19, but not through the peripheral edge adjacent to the outlet groups 14 which forms the peripheral edge of the segments 23. It will be apparent from Figure 2, that the arrangement is such -as to define air delivery 25 chutes 29 between the closed segments 23, 33. These chutes 29, some of which are identified in Figure 2, diverge from a radially internal position to the peripheral edge 11. Each chute 29 includes an outlet column 18 along a wall 21 which defines the respective chute. 30 Referring to Figure 5, the base 30 includes a centrally positioned circular connection ring or flange 38, which is flared at the end section 39 and which includes lengthwise slots 40 for accepting a pipe connection of a pressurised air source. W:Uulie\Andrew\Speci\Injection Device.doc 11 It will be appreciated that when the plate 10 is fitted to the base 30, by screw fasteners extending through the openings 24 into threaded spigots 41, that the free edges 37 of the walls 21 and 22, are accepted into the grooves 36 of the segments 33 to define closed segment chambers. As will be apparent, air 5 which is forced into the assembly of the plate 10 and the base 30, through the flange 38, can flow into the open areas of the plate 10 outside of the segments 23 and can therefore flow out of all of the provided openings 15, 18 and 19. However, no air will flow through the segments 23 and therefore at the peripheral edge 11 and 31 of the assembly, air discharge does not take place at 10 the peripheral regions 42 (see Figure 3). By this arrangement, the plate 10 defines outer surface segments, defined by a pair of the outlet columns 18, an outlet group 14, and a closed peripheral region 42. Such a segment 43 is shown cross-hatched in Figure 3. 15 In use, air discharged through the various outlets defining the segment 43 forms a curtain of rising bubbles, which tend to drag water within the segment 43 upwardly as the bubbles rise. That creates an area of low pressure within the segment 43, and in absence of water to replace that which is dragged upwardly, the bubbles would tend to move towards each other, and merge at a position 20 above the plate 10. Thus, large single bubbles would be created, which is undesirable. However, by providing the closed peripheral region 42, water can be drawn into the segment 43 across that region to replace the water which rises with the bubbles discharged through the various outlets, and this maintains the water pressure within the segment 43, or at least minimises its 25 reduction, so that the bubbles discharged through the various outlets remain separated as they rise, as required. It will be readily appreciated that the bubble discharge provided by the present invention advantageously overcomes the difficulties associated with earlier 30 prototypes developed by the applicant. In particular for spas, an extremely desirable bubble distribution can be achieved, which minimises turbulence created at the water surface. W:\Juie\Andrew\Speci\lnjection Device.doc 12 The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description. W:\JulieAndrew\Speci\lnjection Device.doc

Claims (20)

1. An injection device for injection of gas into liquid, including a chamber which communicates with a gas supply, said chamber being 5 defined partly by a gas distribution plate having a plurality of gas outlets, said plate including a peripheral edge and a broad outer facing upper surface bounded by said edge, said outlets are formed at both said peripheral edge and inwardly of said edge through said plate, wherein said outlets are distributed such that, upon egress of gas through said outlets l0 and into a liquid to form gas bubbles, said liquid is drawn from beyond said peripheral edge over said upper surface of said plate to regions internally of said edge and said liquid drawn internally rises with said gas bubbles to an upper surface of said liquid due to frictional engagement between said gas bubbles and said liquid. 15

2. An injection device according to claim 1, wherein said air outlets at said peripheral edge are provided in spaced-apart groups which are separated from each other by closed edge regions absent of outlets, said closed edge regions being substantially or completely closed against egress or discharge of gas therefrom. !0

3. An injection device according to claim 2, each said outlet group including four outlets.

4. An injection device according to any one of claims 1 to 3, wherein said outlets formed at said peripheral edge extend through said plate at said peripheral edge. 25

5. An injection device according to any one of claims 1 to 4, said chamber being defined by said plate and a base, wherein said plate and said base are connectable together and said base extends to said peripheral edge of said plate and seals with said plate at said edge, so that air discharged through said peripheral edge is 30 discharged only through said outlets formed at said peripheral edge.

6. An injection device according to claim 5, wherein said outlets formed at said peripheral edge extend through said base at said peripheral edge. 14

7. An injection device according to claim 4, wherein said plate is generally circular defining a generally circular peripheral edge and said outlets formed through said peripheral edge of said plate are formed as elongate slots extending inwardly away from said peripheral edge. 5

8. An injection device according to claim 7, wherein said elongate slots converge slightly inwardly as said slots extend inwardly.

9. An injection device according to any one of claims 1 to 8, wherein at least 10 some of said outlets formed inwardly of said peripheral edge are formed in a circular pattern.

10. An injection device according to claim 9, wherein said outlets formed inwardly of said peripheral edge are disposed in a ring formed at a constant radius about the 15 centre of said plate.

11. An injection device according to any one of claims 1 to 10, wherein said outlets formed inwardly of said peripheral edge includes generally linear lines of outlets which radiate from a position approaching the centre of said plate to a position toward said !0 peripheral edge.

12. An injection device according to claim 11 when dependent on either one of claims 9 or 10, wherein said lines of outlets extend to a position adjacent said circular pattern of outlets. 25

13. An injection device according to claim 11 or 12, wherein said lines of outlets are spaced apart equally.

14. An injection device according to claim 13, wherein six lines of outlets are 30 provided.

15. An injection device according to claim 1, wherein said chamber is configured so that gas is delivered from said gas supply to said spaced-apart groups of outlets only, and not to said closed edge regions. 'rd. a . 15

16. An injection device according to claim 15, wherein said chamber is configured to form a plurality of delivery chutes, said chutes being in communication with said gas supply and extending to each outlet group. 5

17. An injection device according to claim 16, said chamber being defined by said plate and a base, wherein said plate and said base are connectable together and said chutes are formed by walls extending between and in engagement with internally facing surfaces of said plate and said base. 10

18. An injection device according to claim 17, said walls extending from said plate to said base and being accepted into a groove or channel formed in or upstanding from said base. 15

19. An injection device according to claim 17, said walls extending from said base to said plate and being accepted into a groove or channel formed in or upstanding from the plate.

20. An injection device substantially as herein described with reference to the !0 accompanying drawings. DATED: 12 August 2004 25 PHILLIPS ORMONDE & FITZPATRICK Attorneys for: SPA ELECTRICS PTY LTD