AU2019204264B2

AU2019204264B2 - A water tank solar shield

Info

Publication number: AU2019204264B2
Application number: AU2019204264A
Authority: AU
Inventors: Shaun CROSSMAN; Anton Lee See
Original assignee: Rain Harvesting Pty Ltd
Current assignee: Rain Harvesting Pty Ltd
Priority date: 2018-06-18
Filing date: 2019-06-18
Publication date: 2025-05-08
Anticipated expiration: 2039-06-18
Also published as: AU2019204264A1

Abstract

A solar shield operable for installation in an inlet of a water tank is disclosed. The solar shield has at least one opening or gap therein to allow water to pass through the solar shield, and each opening extends along or around at least a portion of the solar shield near an outer edge of the solar shield. When the solar shield is installed in the inlet of the water tank, there is no direct line-of-sight access for sunlight to travel through the opening(s) into the tank, so sunlight has to reflect or bounce off at least one wall or surface of the solar shield before entering the tank (if it can enter the tank at all). The configuration of the solar shield is such that water is required to travel/flow/move in an outward direction relative to a geometric centre of the solar shield in order to pass through the opening(s) into the tank, or at least a component of the water's overall travel/flow/movement direction must be in an outward direction relative to the geometric centre of the solar shield. 1/5 Fiur b ¼ (;( - - ---- Fge Figure 2

Description

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A WATER TANK SOLAR SHIELD FIELD OF THE INVENTION

[0001] The present invention relates to devices for preventing sunlight from entering water tanks, including (but not limited to) rainwater tanks.

BACKGROUND

[0002] It is to be clearly understood that mere reference in this specification to any previous or existing products, devices, apparatus, systems, methods, ways of doing things, practices, publications or indeed to any other information, or to any problems or issues, does not constitute an acknowledgement or admission that any of those things, whether individually or in any combination, were known or formed part of the common general knowledge of those skilled in the field, or that they are admissible prior art.

[0003] In rainwater tanks, the water to be stored in the tank (which may be collected from e.g. the roof of a nearby house, building or the like) typically enters the tank either via a pipe or pipes connected directly to (i.e. plumbed into) the tank, or otherwise through an open inlet in the tank. The present invention is concerned mainly with the latter situation, namely where the water to be stored in the tank enters the tank through an open inlet in the tank. Such open tank inlets are typically located in the top of the tank, and they are usually circular.

[0004] Note that, whilst the water to be stored in the tank may often be collected rainwater, it could also be water obtained or flowing or pumped from a range of other sources such as e.g. a nearby stream, or from a dam or reservoir, or from a water truck or tanker, etc. Hence, the present invention is applicable to rainwater tanks, but also to tanks used for storing water other than rainwater (or just rainwater).

[0005] It is common for the inlet in the top of a water tank (i.e. the open inlet through which water is received into the tank) to be provided with a mesh screen covering the inlet. Such mesh screens are sometimes (and will be herein) referred to as tank screens. The mesh of the tank screen allows water to enter the tank, but it prevents leaves and other debris (including leaves and other debris that may be entrained in the flow of incoming water) from entering the tank. The grade of the mesh (i.e. the size of the openings in the mesh) is usually such that the mesh also prevents mosquitoes and the like from entering the tank.

[0006] Tank screens generally cover the whole of the tank inlet. (They generally must cover the whole tank inlet because, otherwise, debris, or water containing entrained debris, or mosquitoes, etc, could enter the tank through portion(s) of the inlet not covered by the tank screen.) Furthermore, the mesh (or the mesh portion(s)) of the tank screen typically extends across most of the tank inlet. In other words, at least most of the area of the tank inlet is covered by the mesh of the tank screen. One consequence of this is that (unless a device like a tank solar shield is provided) tank screens (and in particular mesh portion(s) thereof) can often allow a substantial amount of sunlight to enter the tank. Basically, sunlight can often pass directly through the mesh (or mesh portion(s)) of the tank screen and into the tank. This can be undesirable because, for example, sunlight (particularly direct sunlight entering the tank) can stimulate growth of algae and the like inside the tank. It is therefore thought to be desirable to prevent as much sunlight as possible (especially direct sunlight) from entering the tank.

[0007] Devices which prevent sunlight (or at least some sunlight or some direct sunlight) from entering the tank through the tank inlet are sometimes called tank solar shields. Some currently available solar shields are "top cover" style products which sit over the top of (i.e. they are positioned and reside generally above) the tank screen and tank inlet to thereby shield the tank inlet against sunlight. In other words, these "top cover" style solar shields essentially operate by causing the tank inlet (including the tank screen located therein) to be in the shade of the solar shield, thereby preventing direct sunlight (or at least some direct sunlight) from entering the tank. There are instances where these top cover style solar shields are suitable. For example, because top cover style solar shields physically extend over the tank inlet, their use can sometimes be desirable in order to prevent or inhibit access to the tank inlet by pests, vermin, and the like, because the top cover style solar shield creates a physical barrier to such pests. Also, because top cover style solar shields create a physical barrier extending over the top of the tank inlet, they can also help to prevent or limit airborne debris and the like from landing on/in the tank inlet. Another situation where top cover style solar shields can be desirable is in tanks in which the tank's overflow outlet is located very high in (or almost at the top of) the tank - in these situations, because the tank overflow outlet is so high, it may be possible for the level of the water in the tank to rise to almost reach, reach, or even rise above and swamp/submerge the tank screen (and hence also an in-tank solar shield (as described below) if one of these were to be used). However there are also instances where, and/or reasons why, top cover style solar shields may be less desirable, and it is these latter instances (i.e. where top cover style solar shields are less desirable or unsuitable) that the present invention mainly focuses on. One reason why top cover style solar shields may often be less desirable in certain situations (particularly where their specific benefits discussed above are not required), is because their installation is typically more difficult and time-consuming (e.g. compared to in-tank style solar shields - see below). For top cover style solar shields, because the solar shield extends over the top of the tank inlet, it is necessary for the pipes, etc, which deliver water into the tank inlet to be precisely aligned with the holes formed in the solar shield designed to receive those pipes. This can increase the difficulty/complexity of installation. In comparison, with the in-tank style solar shields discussed below, the pipe(s), etc, which deliver water into the tank can be positioned to empty anywhere above the tank inlet/tank screen, which can make installation quicker and easier.

[0008] In instances where a top cover style solar shield is undesirable or unsuitable, an in-tank style solar shield solution may often be preferred. "In-tank" here means a solar shield that is installed and resides in the tank inlet. Usually, in tank solar shields are installed, and they reside, beneath (i.e. under) a tank screen that is also installed in the tank inlet.

[0009] One consideration affecting the design of tank solar shields, and in particular in-tank solar shields, is the need (at least usually) to maximise the amount of (or the rate at which) water can pass through the solar shield into the tank. Ultimately, the purpose of a water tank is to store in-flowing water, so should the design of an in-tank solar shield be such that situations arise (or could arise) where water is flowing (or could flow) into the tank inlet faster than it can pass through the in-tank solar shield installed in the tank inlet, the natural consequence of this is that the water will begin to pool/fill up above the solar shield, then progressively above the tank screen, and ultimately it may begin spilling over the rim of the tank inlet and down the side of the tank, in which case the spilled water is lost and wasted, not collected in the tank for later use. Of course, this leads to (or it implies) a design challenge in that the solar shield may be required (on the one hand) to allow as much water through as possible, whilst at the same time (i.e. on the other hand) the solar shield may also be required to prevent penetration by as much sunlight as possible (if not all sunlight). In other words, it can be a design challenge to meet, or balance, these potentially competing requirements.

[0010] Another issue associated with many currently available in-tank style solar shields, or with the way these current in-tank style solar shields operate in conjunction with (i.e. when installed in a tank inlet and used together with) a tank screen, is that they provide little attenuation of the flow of water entering the tank. This can mean that, particularly during (and immediately following) periods of heavy rainfall, water flowing through the tank screen, through the solar shield and into the tank can enter the tank fast and/or violently and/or otherwise in a manner that can "stir up" sediment that may have previously settled to the bottom of the tank, and this can thereby cause resuspension of that sediment throughout the main body (or throughout the volume) of the water stored in the tank. In other words, the sediment (which may previously have fallen out of suspension and settled to the bottom of the tank) can become stirred up and resuspended/redispersed/redistributed in the tank, rather than remaining confined to a layer at the bottom of the tank. The health/quality of water inside the tank, and hence the health/quality of water drawn from the tank, is generally improved if any sediment that may be within the tank remains settled at the bottom. Otherwise, if the sediment is stirred up and/or resuspended in the tank (as discussed above), this can lead to turbidity and/or discolouration of the water, and even to e.g. heavy metals (or the like) being resuspended in or redistributed into the main body of the water, rather than remaining confined to (and therefore isolated in) the layer of settled sediment at the bottom of the tank.

[0011] It is thought that it may be desirable if one or more of the problems or issues discussed above could be overcome, or at least reduced somewhat, or improved upon.

SUMMARY OF THE INVENTION

[0012] In one form, although not necessarily the only or the broadest form, the invention resides in a solar shield operable for installation in an inlet of a water tank (tank inlets are normally circular; however the invention is not necessarily limited to circular tank inlets, so the invention could also provide solar shields for non-circular tank inlets), the solar shield having at least one opening (or gap) therein to allow water to pass through the solar shield, each opening extending along or around at least a portion of the solar shield near an outer edge of the solar shield, wherein, when the solar shield is installed in the inlet of the water tank, there is substantially no (i.e. no or almost/virtually no) direct line-of-sight access for sunlight to travel through the opening(s) (and preferably also not otherwise through or around the solar shield) into the tank (in other words sunlight should have to reflect or bounce off at least one wall or surface of e.g. the solar shield or tank/tank inlet before entering the tank), and (the configuration of the solar shield is such that) water is required to travel/flow/move in an outward direction relative to a geometric centre of the solar shield (or relative to a centre of the solar shield's planform shape) in order to pass through the opening(s) into the tank, or at least a component of the water's overall travel/flow/movement direction must be in an outward direction relative to the geometric centre of the solar shield (or relative to the centre of the solar shield's planform shape). If or when (or in embodiments in which) the solar shield is circular in overall planform shape, this will generally mean the water is required to flow in a radially outward direction relative to the geometric centre of the solar shield's circular planform shape in order to pass through the opening(s), or at least a component of the water's flow direction should be in radially outward. Because water is required to flow generally outwardly in order to pass through, and also as it passes through, the openings in the solar shield, it may be (at least in some embodiments) that the water also or consequently flows through and out of the solar shield in a dispersed manner. Where this is the case, this effect might perhaps be considered as somewhat akin to the way a showerhead disburses or distributes water rather than causing the flow therethrough to become directed in a narrowly focussed or concentrated fashion. The fact that the flow of water passing through the solar shield and into the tank may be disbursed or distributed may help to prevent sediment from being stirred up within the tank.

[0013] It is envisaged that solar shields in accordance with embodiments of the present invention will generally be in-tank solar shields (although no strict limitation is to be implied in this regard and the invention could also potentially take forms other than in-tank forms).

[0014] The solar shield may have a main horizontal portion that extends across the tank inlet and a plurality of arms that extend upwardly from the main horizontal portion to engage with a rim of the tank inlet (these arms may be for mounting the solar shield in the tank inlet).

[0015] As alluded to above, the solar shield may have a circular planform shape. In embodiments where the solar shield has a circular planform shape:

- there may be at least one opening through which water can pass through the solar shield and which extends around at least a portion of the circumference (or possibly around the full circumference) of the solar shield near the outer edge of the solar shield, or

- there may be multiple openings through which water can pass through the solar shield, and each opening may extend around at least a portion of the circumference of the solar shield near the outer edge of the solar shield. In some cases, each opening may extend around the full circumference of the solar shield, with one of the openings being located closest to the outer edge of the solar shield and the other opening(s) being located inwardly thereof relative to the outer edge of the solar shield.

[0016] As mentioned above, the solar shield may have a main horizontal portion. The main horizontal portion may include a central cover portion and an outer cover portion (a first outer cover portion) located relatively on the outside of (possibly surrounding) the central cover portion, and an inner edge of the (first) outer cover portion may be positioned higher than/above an outer edge of the central cover portion such that an opening (a first opening) is formed between the outer edge of the central cover portion and the inner edge of the (first) outer cover portion.

[0017] The main horizontal portion of the solar shield may further include a second outer cover portion located relatively on the outside of (possibly surrounding) the (first) outer cover portion, and an inner edge of the second outer cover portion may be positioned higher than/above an outer edge of the (first) outer cover portion such that a second opening is formed between the outer edge of the (first) outer cover portion and the inner edge of the second outer cover portion.

[0018] The main horizontal portion of the solar shield may further include an outer wall, the inside of the outer wall may have a shading rim extending inwardly therefrom, and an inner edge of the shading rim may be positioned higher than/above an outer edge of the second outer cover portion such that a third opening is formed between the outer edge of the second outer cover portion and the inner edge of the shading rim.

[0019] The solar shield may further including one or more baffles extending generally vertically from an underside of the main horizontal portion and which is/are located slightly to the outside of the opening(s) to prevent direct line-of-sight access for light through the openings.

[0020] The solar shield may also include one or more features operable to limit the amount or the extent to which water flows in a direction transverse to the direction outward relative to the geometric centre of the solar shield.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Preferred features, aspects and variations of the invention and its various embodiments may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting, in any way, the scope in the Summary of the Invention above. The Detailed Description will make reference to a number of drawings as follows:

[0022] Figure 1 is a perspective view of a solar shield in accordance with one possible (albeit non-limiting) embodiment of the invention.

[0023] Figure 2 shows a tank screen installed on top (or in the top) of the solar shield of Figure 1. In other words, Figure 2 illustrates the way the solar shield of Figure 1 is mounted beneath the tank screen in the tank inlet (albeit the tank itself, and the tank inlet itself, are not shown).

[0024] Figure 3 is a top view of (i.e. a view from directly above) the solar shield in Figure 1.

[0025] Figure 4 is an underside view of (i.e. a view from directly underneath) the solar shield in Figure 1.

[0026] Figure 5 is a side view of the solar shield in Figure 1 (i.e. a view looking horizontally at the solar shield from the side).

[0027] Figure 6 is another side view of the solar shield in Figure 1 (i.e. it is also a view looking horizontally at the solar shield from the side), except that Figure 6 shows the solar shield from a slightly different angle compared to Figure 5.

[0028] Figure 7 is a side on cross-sectional view of the solar shield in Figure 1 when the cross-section is taken in the vertical plane marked 7-7 in Figure 3.

[0029] Figure 8 is a perspective cross-sectional view of the solar shield in Figure 1 when (like in Figure 7) the cross-section is taken in the vertical plane marked 7-7 in Figure 3.

[0030] Figure 9 contains a number of views (including cross-sectional views) of a currently-available (i.e. prior art) in-tank solar shield.

[0031] Figure 10 contains photographs of:

(i) the flow of water entering a water tank (or a test apparatus representing or simulating a water tank) after passing through a tank screen and then through the currently-available (prior art) solar shield shown in Figure 9; and

(ii) the flow of water entering the tank (or the same test apparatus representing or simulating the water tank) after passing through a tank screen and then through a solar shield in accordance with an embodiment of the invention (note that the embodiment of the solar shield in Figure 10(ii) is not necessarily exactly the same embodiment as described in Figure 1 to Figure 8).

DETAILED DESCRIPTION

[0032] As mentioned above, Figure 1 is a perspective view of a solar shield 100 in accordance with one possible embodiment of the invention. It is the solar shield 100 in this particular embodiment that will mainly be further described with reference to later Figures.

[0033] As also mentioned above, Figure 2 shows a tank screen 20 positioned above the solar shield 100. In other words, Figure 2 illustrates the way the solar shield 100 is mounted beneath the tank screen 20 in the tank inlet (albeit the tank itself, and the tank inlet itself, are not shown). Basically, the solar shield 100 is first inserted into the circular tank inlet, and if necessary (or optionally) it can be secured in place therein (as discussed below). Then the tank screen 20 is inserted into the tank inlet on top of the solar shield 100 as shown in Figure 2, and if necessary (or optionally) the tank screen can also then be secured in place in the tank inlet (as discussed below).

[0034] The solar shield 100 has a main circular lower portion 120, and a number of (in this case four) arms 160 which extend upwardly from the main lower circular portion 120. The number of arms can vary depending on the size of the solar shield. For instance, the solar shield 100 in this particular embodiment has a configuration that makes it suitable to be sized for installation and use in tank inlets having a diameter of around 400 mm. However, it is also common for water tanks to have inlet openings of other diameters. Other common water tank inlet diameters include 300 mm and 500 mm. Embodiments of the invention could easily be made with configurations suitable to be sized and used in these other sized (and further other sized) tank inlets, and by way of example, a solar shield in accordance with a different embodiment of the present invention sized for use in a 300 mm tank inlet could have, say, three arms similar to the arms 160 shown in the Figures, and a solar shield in accordance with a further embodiment of the invention sized for use in a 500 mm tank inlet could have, say, six arms like the arms 160. Different sized embodiments of the invention may also differ in other ways. For example, in addition to having a larger or smaller diameter, the overall height of the solar shield may also be larger (for larger diameter solar shields) or smaller (for smaller diameter solar shields). Also, the number of the spokes (see below) may be more than is shown in the Figures for larger diameter solar shields and fewer for smaller diameter solar shields. Larger diameter solar shields could also (potentially) have a greater number of the annular covering rings and hence a greater number of openings through the solar shield (see below), etc. Other variations of a generally similar nature may be apparent to those skilled in the art and all are considered to fall within the scope of the invention.

[0035] Referring again to the solar shield 100 in the particular embodiment depicted in Figure 1 to Figure 8, it will be seen that, at the top of each of the arms 160, there is outwardly extending portion 162. The undersides of these outwardly extending portions 162 engage with, and come to rest on, the upper rim of the circular tank inlet (not shown) when the solar shield 100 is installed in the tank inlet.

[0036] In order to mount the solar shield 100 in the tank inlet, the solar shield 100 is inserted into the circular tank inlet in the orientation shown in Figure 1 and Figure 2. Thus, when the solar shield 100 is inserted into the tank inlet, the main circular lower portion 120 of the solar shield 100 passes through the circular tank inlet and becomes positioned (i.e. it comes to reside) just inside the tank, below the tank inlet. Also, as alluded to above, when the solar shield 100 is fully inserted into the circular tank inlet, the undersides of the outwardly extending portions 162 of the arms 160 come to rest on top of the rim of the circular tank inlet.

[0037] It will also be seen that, in the middle of each of the outwardly extending portions 162, there is a pre-formed screw hole 164. If necessary, or if desired, once the solar shield 100 has been fully inserted into the tank inlet and the undersides of the outwardly extending portions 162 are resting on the rim of the tank inlet, screws (not shown) can be inserted into the screw holes 164 and then driven into the rim of the tank inlet to thereby secure the solar shield 100 in place in the tank inlet.

[0038] It is to be noted that, instead of the arms 160 just described, the solar shield could instead be provided with a solid annular wall having an annular rim/lip thereon for use in installing the solar shield in the tank inlet (i.e. similar to the prior art solar shield shown in Figure 9). If so, the solar shield would still operate in substantially the same way in normal operation (assuming the features of the solar shield's main circular portion 120 are as discussed below). However, one possible additional advantage of providing the arms instead of a solid annular wall for mounting the solar shield in the tank inlet is that the spaces between the arms provide open spaces which can act as an escape passage for water to pass between the solar shield and the internal wall of the tank inlet (i.e. and then into the tank), e.g. in the case of extremely high flow rates of water entering the tank (in other words this may help to prevent a situation where the water level simply fills up within the solar shield and spills out over the top of the tank inlet and out of the tank).

[0039] Referring now to Figure 2, it will be appreciated that once the solar shield 100 has been inserted into the tank inlet, as described above, the tank screen 20 can then simply be inserted into the tank inlet directly on top of the solar shield 100. The tank screen 20 is not part of the present invention. However, it can be seen from Figure 2 that the tank screen 20 has:

- an annular rim 22 at the top which (when the tank screen is installed) sits over the rim of the tank inlet, on top of the outwardly extending portions 162 of the arms 160 (and in fact on top of the arms 160 generally) of the solar shield 100;

- a substantially cylindrical wall 24 extending downward from the inner edge of the annular rim 22 (note that this substantially cylindrical wall 24 may taper inwards slightly as it moves down in order to fit inside, and not collide with, the solar shield);

- a number of mesh supporting ribs 26 which extend radially (and generally horizontally) inwards from the lower edge of the cylindrical wall 24 to meet in the centre at a generally round hub portion 28;

- a number of concentric circular mesh supporting rings 30 surrounding the hub portion 28 - these connect each one of the ribs 26 to the two adjacent ribs, at different radii out from the hub portion 28; and

- mesh 32 which essentially covers the entire space inside the cylindrical wall 24 at the base of the tank screen 20, and the mesh 32 extends over (and is supported by) the mesh supporting ribs 26 and the mesh supporting rings 30.

[0040] The purpose and function of the tank screen 20 is as described in the Background section above. Basically, the mesh 32 allows water to enter the tank, but it prevents leaves and other debris, and also mosquitoes and the like, from entering the tank. The mesh supporting ribs 26 and mesh supporting rings 30 support the mesh 32 from underneath to stop it from bowing downwards or tearing or etc under the weight of impinging water (and also if struck by falling leaves or sticks or the like entrained in the flow of water).

[0041] Turning now to the configuration of the solar shield 100 itself, as mentioned above, the solar shield 100 includes a main circular lower portion 120, and a number of (in this case four) arms 160 which extend upwardly from the main lower circular portion 120. The function of the arms (and the various parts and features of them at the top) has previously been described. However, it should also be noted that the vertically extending portion 166 of each of the arms has a fairly thin, part-cylindrical shape. In other words, the vertical portion 166 of each of the arms 160 is shaped like a fairly small portion of (or a small arc of) a larger thin cylinder. The reason why the vertical portion 166 of each of the arms is fairly thin is so that the arms 160 (which become located directly within the circular opening of the tank inlet when the solar shield 100 is inserted therein) do not unduly impede the insertion of a tank screen (like e.g. the tank screen 20). Actually, in the particular tank screen 20 depicted in Figure 2, the cylindrical wall 24 of the tank screen incorporates four inward indents 25, one to accommodate each vertical portion 166 of a respective arm 160 of the solar shield 100. This helps this particular tank screen 20 to better fit over/into the solar shield 100 in the tank inlet. This may also help to align this particular tank screen 20 with the solar shield 100 so that the same screws used (if necessary or desired) for securing the solar shield 100 in place can also be used to secure the tank screen 20. (In other words, rather than using screws to secure the solar shield 100 in place before the tank screen 20 is inserted, the solar shield 100 can simply be inserted into the tank inlet, followed by the tank screen, and then a single screw can be inserted through each one of the pre-formed screw holes visible in the annular rim 22 of the tank screen 20, and also through the corresponding screw hole 164 in the solar shield arm located directly therebeneath, and then into the rim of the tank inlet, to thereby secure the solar shield 100 and the tank screen 20 in position in the tank inlet). However, for the avoidance of doubt, the presence of the indents 25 is not essential, and nor is the ability to align the tank screen in a particular manner with the solar shield, or to use of common screws to secure the solar shield and tank screen, etc. Indeed a range of different tank screens (including ones which do not include indents 25) could potentially also be used with the solar shield 100. In any case, as mentioned above, the tank screen is not even part of the present invention.

[0042] At the base of each of the vertical portions 166 on the respective arms 160, where these join to the outer wall of the solar shield's main lower circular portion 120, the vertical portions 166 curve outwards on either side (see 167), and there are also a number of stiffening ribs 168 provided on (or below) the inner face and on (or below) the outer face of the vertical portion 166. The outward curvatures 167 serve to minimise stress concentrations, and the stiffening ribs 168 serve to reinforce/stiffen the arms 160 relative to the main lower portion 120 (i.e. these stiffening ribs 168 help to stop the arms 160 from being able to flex too much radially in an out relative to the main portion 120).

[0043] Turning now to the main circular lower portion 120 of the solar shield 100, it can be seen from the Figures that this has a cylindrical outer wall 122. At the locations where the arms 160 extend upwardly relative to the main circular lower portion 120, the arms 160 are integrally formed with the outer wall 122, such that the arms 160 effectively form upwardly extending extensions of the outer wall 122.

[0044] Inside the outer wall 122, the main circular lower portion 120 includes a central cover portion 130. The central cover portion 130 is circular in planform shape (see Figure 3), and it is generally fairly flat (in the sense that it is considerably wider than it is tall - this is important because if the central cover portion 130 were too tall this could prevent or impede a tank screen from being inserted on top of the solar shield). However, it is very important to note that the central cover portion 130 is not perfectly flat. Rather, the central cover portion 130, although fairly flat, nevertheless has a slight tepee-like shape in that the lowermost point of the central cover portion 130 is at the outermost perimeter edge, and moving inward from the outermost perimeter edge the central cover portion 130 curves upwards to a highest point where it meets a small, round and flat (generally horizontal) central portion 132 in the centre.

[0045] The purpose of the slightly tepee-like shape of the central cover portion 130 will now be described. The region of the central cover portion 130 were it is most steeply sloped is in the middle, near where the central cover portion 130 meets the central portion 132. Therefore, any water which (after passing through the tank screen) then lands on the central cover portion 130 near the inside/middle (i.e. near the central portion 132) will thereafter experience the greatest gravitational force (or the greatest component of gravitational force) urging that water to continue to flow outwards towards and over the outside edge of the central cover portion, due to the comparatively steep slope of the upper surface of the central cover portion 130. In comparison, any water which (after passing through the tank screen) lands on the central cover portion 130 closer to the outside of the central cover portion 130 will experience a relatively much lower gravitational force (or a lower component of gravitational force) urging that water to continue to flow outwards towards and over the outside edge of the central cover portion. The fact that water that lands closer to the outside of the central cover portion 130 experiences less of a gravitational acceleration towards the outside (due to the comparatively less steep slope of the central cover portion 130 near the outside) is important because this may help somewhat to attenuate the flow (i.e. the speed/velocity of the flow) of water as it passes over and through the solar shield. A reason why the slope of the central cover portion 130 closer to the inside/middle is comparatively steeper is that water that lands on the solar shield closer to the inside/middle of the central cover portion consequently must travel further (i.e. a greater distance) over/across the upper surface of the central cover portion 130 before passing over the outer/perimeter edge thereof. Therefore, a slightly greater gravitational force/acceleration may be needed for (or it may at least help) water that falls closer to the inside/middle of the central cover portion 130 to flow across and through the solar shield, by helping to give that water sufficient momentum to flow radially all the way out across the central cover portion 130 and over the perimeter edge thereof.

[0046] Inside the outer wall 122, the main circular lower portion 120 of the solar shield 100 also includes a number of radially extending spoke members (hereafter "spokes") 140. In this particular embodiment there are 16 spokes 140; however as mentioned above the number of spokes may vary in other embodiments (e.g. for solar shields of different sizes and/or for other reasons such as the need to provide greater or lesser rigidity, greater or lesser radial flow control, etc). Each of the spokes 140 extends from the central portion 132 all the way out to the outer wall 122. In terms of the purpose and function of the spokes, firstly, they help to support the central cover portion 130 and also the outer annular ring cover portions (see below). In other words, it is the spokes 140 that joins/connects the central cover portion 130 (including the central portion 132), and also each of the outer annular ring cover portions, to the outer perimeter wall 122. It is therefore the spokes 140 that provides the structure which physically connects and supports/suspends the central cover portion 130 and the outer annular cover portions in position relative to (i.e. in the air/space in the middle of) the solar shield. However, in addition to this, the spokes 140 also help prevent water which passes through the tank screen and lands on the solar shield 100 (whether by striking the central cover portion 130 or one of the outer annular ring cover portions) from flowing in a significantly circumferential direction relative to the solar shield. Instead, the spokes 140 help to ensure that water that lands on the central cover portion 130 or one of the outer annular ring cover portions is directed to flow mainly only radially outwards before passing out through one of the various openings in the solar shield. Basically, the spokes 140 help to channel water that lands on the solar shield so that it follows over and through the solar shield in generally radially outward flow direction. Ensuring that water striking the solar shield is directed to flow mainly only radially outwards is another part of what may help the solar shield 100 in the present embodiment of the invention to improve flow attenuation (i.e. to calm the flow).

[0047] The main circular lower portion 120 of the solar shield 100 also incorporates (as mentioned above) a number of annular ring like cover portions. These are located generally radially to the outside relative to the central cover portion 130. In the particular embodiment shown, the solar shield 100 has two outer annular ring like cover portions, which will be referred to as the inner annular covering ring 150 and the outer annular covering ring 170. Both the inner annular covering ring 150 and the outer annular covering ring 170 are higher at the inside circumferential edge thereof and lower at the outside circumferential/perimeter edge thereof. Hence, both slope downward in a radially outward direction. Also, as best shown in Figure 7, the circumferential inside edge of the inner annular covering ring 150 is located above the outer perimeter edge of the central cover portion 130 so that there is a first gap in (i.e. a first opening through) the solar shield between the outer perimeter edge of the central cover portion 130 and the circumferential inside edge of the inner annular covering ring 150. Similarly, the circumferential inside edge of the outer annular covering ring 170 is located above the circumferential outer perimeter edge of the inner annular covering ring 150 so that, again, there is a (second) gap in (i.e. a second opening through) the solar shield between the outer perimeter edge of the inner annular covering ring 150 and the circumferential inside edge of the outer annular covering ring 170. Furthermore, there is a small annular shading rim 180 which extends inward from the inside surface of the wall 122 around the full circumference of the wall 122. This annular shading rim 180 has a cross-sectional shape that generally resembles an inverted "L", as best shown in Figure 7 and Figure 8. The lower, innermost edge of the annular shading rim 180 is located above the circumferential outer perimeter edge of the outer annular covering ring 170 so that, yet again, there is a (third) gap in (i.e. a third opening through) the solar shield between the outer edge of the outer annular covering ring 170 and lower, innermost edge of the annular shading rim 180. The first, second and third gaps mentioned above are the (circular/annular) openings in the solar shield which allow water that strikes or lands on the solar shield after passing through the tank screen to pass through the solar shield and into the tank. In relation to the inner annular covering ring 150 and the outer annular covering ring 170, the fact that these both slope downward in radially outward direction helps to ensure that water that strikes these after passing through the tank screen flows in a radially outward direction before passing through the relevant gap and into the tank. Furthermore, the spokes 140 also help to ensure that any water that strikes either of the annular covering rings flows mainly only in a radially outward direction before passing through the relevant gap and into the tank (i.e. the spokes 140 once again help to minimise the extent of flow in a significantly circumferential direction).

[0048] Still referring to the spokes 140, it will be seen from Figure 4 and Figure 7 in particular that lower portions 142 of the spokes, namely the portions of the spokes located beneath the inner annular covering ring 150 and outer annular covering ring 170 (and also beneath the level of the outermost portion of the central cover portion 130), only extend part of the way inward from the outer wall 122. In other words, the lower portions 142 of the spokes do not extend all the way in to the middle of the solar shield like the upper portions of the spokes 140 do. This is because the lower portions 142 of the spokes do not need to extend all the way in as they mainly only serve, firstly, to support the inner and outer annular covering rings 150 and 170, and secondly, to support baffle walls 152 an 172 that depend vertically downwards from the respective inner and outer annular covering rings 150 and 170. The baffle walls 152 and 172 are positioned, and they also extend vertically downward far enough, to prevent direct line-of-sight access for sunlight from the outside of the tank (above the solar shield) into the inside of the tank (below the solar shield) through the first and second gaps. The baffle walls 152 and 172 also help to attenuate flow (i.e. to calm the flow of water as it passes through the first and second gaps and into the tank) because water flowing through the solar shield through the first and second gaps will often (especially during heavy rain with high flow rates or rapid flow velocity) hit these walls before entering the tank, and upon hitting the walls the flow will generally slow down before falling vertically (and more calmly) into the tank. Flow passing out through the third gap will also generally be calmed by striking the wall 122 before falling vertically (and more calmly) into the tank.

[0049] It has been explained that the inside edge of the inner covering ring 150 is located above the outer edge of the central cover portion 130 creating the first gap, and likewise the inside edge of the outer covering ring 170 is located above the outer edge of the inner ring 150 creating the second gap, and the lower, innermost edge of the shading rim 180 is located above the outer edge of the outer covering ring 170 creating the third gap. The position and configurations of the baffle walls 152 and 172 has also been explained. Because of these things, and also because of how far beneath/below the rim of the tank inlet the lower main circular portion 120 of the solar shield sits when installed (due e.g. to the height of the arms 160), it is impossible (or at least almost/virtually impossible) for sunlight to travel directly from outside the tank into the inside of the tank, at least not without first striking (and therefore having to bounce/reflect off) one or more surfaces of the solar shield. In other words, there is no direct line-of-sight access for sunlight from the outside of the tank (above the solar shield) into the inside of the tank (below the solar shield) through any of the gaps on the solar shield. See the wavy lines in Figure 7 which represent rays of sunlight even rays of light at these extreme angles, which may pass into the gaps, still cannot pass unreflected into the tank. In other words, as can be seen, there is no possible line (or trajectory) that a ray of sunlight could take to pass through the solar shield without first striking (and reflecting off) at least one surface of the solar shield. This is the main way the solar shield helps to prevent sunlight from entering the tank. It should also be noted that it is also difficult or impossible for sunlight to pass between the outside of the solar shield (i.e. the outside of outer wall 122) and the inside of the tank inlet into the tank.

[0050] Another point to note is that the collective size/area of the first, second and third openings (i.e. the total size/area of these if they are all added together) allows for quite (or even very) high flow rates (i.e. a high volume of water per unit time) to pass through the solar shield, meaning that the design of the solar shield 100 does not unduly impede or reduce the performance of the tank screen or inhibit water from entering the tank. Also, the circular/annular design/configuration/arrangement of the openings, together with the use/provision of multiple or a greater number of smaller openings, rather than fewer (or even a single) large opening (as in prior art solar shields), may help to effectively calm the water flow. The overall effect could be described as similar to that of a shower head, but inside a water tank. By spreading the flow out in a generally similar manner to a shower head, the velocity of the water may be reduced without reducing much (if at all) the overall throughput.

[0051] For comparison, Figure 9 contains a number of reviews (including cross sectional views) of a currently-available (prior art) in-tank solar shield. In the cross sectional view on the bottom right in Figure 9, arrows indicate the way in which water must flow after entering the prior art solar shield in order to ultimately pass out through the openings in the bottom of the solar shield and into the tank. As can be seen in that image, much of the water that enters the prior art solar shield must initially flow toward the outside before then curving/flowing back inwards in order to pass through the openings formed around the perimeter edge beneath the central cover portion of the solar shield. Thus, in order for most of the flow to pass through these openings, the flow must initially curve outwards, and this causes the flow to impact on and then bounce/reflect back inwards off the inside of the solar shield's annular wall before passing out through the openings in the bottom of the solar shield in a genrallay radially inward direction. Therefore, most (at least) of the flow is consequently directed in a radially inward direction as it passes through the openings in the bottom of the solar shield and into the tank. The consequence of this is depicted in Figure 10(i). As shown in Figure 10(i), because of the way the bulk of the flow bounces off the inside wall of the solar shield before passing through the openings in the base in a readially inward direction, the flow of water exiting through the openings in the solar shield becomes concentrated in a narrow flow column. And because the mass and momentum of all the water entering the tank (in the case of this prior art solar shield) is thus concentrated into this narrow flow column, this flow column (or its momentum) effectively continues (i.e. it is driven by the mass and momentum of the water) all the way down to the bottom of the tank where it may stir up sediment that may have settled on the bottom of the tank.

[0052] In contrast to the above, Figure 10(ii) depicts the flow of water entering the tank after passing through a tank screen and then through a solar shield in accordance with an embodiment of the invention. As this image illustrates, because the design of the solar shield in the depicted embodiment is such that water is required to flow generally outwardly (i.e. in a radially outward direction) in order to pass through the openings in the solar shield, the water consequently flows through and out of the solar shield in a comparatively much more dispersed manner. The effect might perhaps be considered as somewhat akin to the way a showerhead disburses or distributes water rather than causing the flow therethrough to become directed in a narrowly focussed or concentrated fashion. In any case, the fact that the flow of water passing through the solar shield and into the tank is more disbursed may help to prevent sediment from being stirred up within the tank.

[0053] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[0054] In this specification, the terms 'comprises', 'comprising', 'includes', 'including', or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include others elements not listed.

Claims

1. A solar shield operable for installation in an inlet of a water tank,

the solar shield having at least one opening therein to allow water to pass

through the solar shield, each opening extending along or around at least a

portion of the solar shield near an outer edge of the solar shield,

wherein, when the solar shield is installed in the inlet of the water tank,

there is substantially no direct line-of-sight access for sunlight to travel through

the opening(s) into the tank, and

water is required to travel/flow/move in an outward direction relative to a

geometric centre of the solar shield in order to pass through the opening(s) into

the tank, or at least a component of the water's overall travel/flow/movement

direction must be in an outward direction relative to the geometric centre of the

solar shield and, after passing through the opening(s) in the outward direction,

water can fall vertically into the tank without any further horizontal

displacement.

2. The solar shield as claimed in claim 1, wherein the solar shield is an in-tank

solar shield.

3. The solar shield as claimed in claim 1 or 2, wherein the solar shield has a main

horizontal portion that extends across the tank inlet and a plurality of arms that

extend upwardly from the main horizontal portion to engage with a rim of the

tank inlet.

4. The solar shield as claimed in any one of the preceding claims, wherein the

solar shield is circular in planform shape.

5. The solar shield as claimed in claim 4, wherein there is at least one opening

through which water can pass through the solar shield and which extends

around at least a portion of the circumference of the solar shield near the outer

edge of the solar shield.

6. The solar shield as claimed in claim 5, wherein there is at least one opening

through which water can pass through the solar shield and which extends

around the full circumference of the solar shield near the outer edge of the solar

shield.

7. The solar shield as claimed in claim 4, wherein there are multiple openings

through which water can pass through the solar shield, and each opening

extends around at least a portion of the circumference of the solar shield near

the outer edge of the solar shield.

8. The solar shield as claimed in claim 7, wherein each opening extends around

the full circumference of the solar shield, with one of the openings being located

closest to the outer edge of the solar shield and the other opening(s) being

located inwardly thereof relative to the outer edge of the solar shield.

9. The solar shield as claimed in claim 3, or any one of claims 4-8 when

dependent on claim 3, wherein the main horizontal portion of the solar shield

includes a central cover portion and an outer cover portion located relatively on

the outside of the central cover portion, and an inner edge of the outer cover

portion is positioned higher than/above an outer edge of the central cover

portion such that an opening is formed between the outer edge of the central

cover portion and the inner edge of the outer cover portion.

10. The solar shield as claimed in claim 9, wherein the main horizontal portion of

the solar shield further includes a second outer cover portion located relatively on the outside of the outer cover portion, and an inner edge of the second outer cover portion is positioned higher than/above an outer edge of the outer cover portion such that a second opening is formed between the outer edge of the outer cover portion and the inner edge of the second outer cover portion.

11. The solar shield as claimed in claim 10, wherein the main horizontal portion of

the solar shield further includes an outer wall, the inside of the outer wall having

a shading rim extending inwardly therefrom, and an inner edge of the shading

rim is positioned higher than/above an outer edge of the second outer cover

portion such that a third opening is formed between the outer edge of the

second outer cover portion and the inner edge of the shading rim.

12. The solar shield as claimed in claim 3, or any one of claims 4-11 when

dependent on claim 3, further including one or more baffles extending generally

vertically from an underside of the main horizontal portion.

13. The solar shield as claimed in any one of the preceding claims, further including

one or more features operable to limit the amount or the extent to which water

flows in a direction transverse to the direction outward relative to the geometric

centre of the solar shield.