Back-flushing pool skimming system

Abstract

Pool skimming apparatus including a debris collection chamber having a pool-water inlet throat closable by a floating weir, a leaf basket fixed below the debris collection chamber, there being a return water outlet and a backflush water inlet below the leaf basket, and a backflush debris outlet above the debris collection chamber, whereby, in normal operation, the pool water and debris will be drawn past the open floating weir and into the debris collection chamber, with debris being caught in the leaf basket and pool water passing to the return water outlet, and, in backflush operation, water will enter the apparatus from the backflush water inlet below the leaf basket to pass upwardly through the leaf basket to force debris in the leaf basket up into the debris collection chamber, past the closed floating weir and out the backflush debris outlet.

Description

Back-flushing pool skimming systemTechnical Field

[0001] The present invention relates to skimming systems for swimming pools, including both apparatus and methods for skimming and removing debris from the surface of a swimming pool.Background of Invention

[0002] Swimming pools are normally equipped with skimming equipment to remove debris floating on the surface of the pool, the skimming equipment being connected to a recirculating fluid system situated away from the pool which includes a pump for drawing pool water from the pool through a skimmer box built into a side wall of the pool. The skimmer box normally includes a removable filter basket (often called a “leaf’ basket) for catching debris in the water moving therethrough, with the coarsely filtered water then being passed from below the leaf basket out of the skimming equipment to a fine filtration system, usually situated with the pump away from the pool, before subsequently being returned to the pool.

[0003] The throat of the skimmer box, between the skimmer box and the pool wall, usually includes a floating weir that auto-adjusts to rising or falling water levels in a manner that permits debris to flow past the weir into the skimmer box when water is being drawn into the skimmer box by the pump, but to prevent debris from floating back out of the skimmer box into the pool when the pump is not operating.

[0004] Skimming equipment of this type thus operates reasonably simply to extract and retain floating debris from the surface of a pool and to permit pool water to also be further filtered or treated before being returned to the pool. However, such equipment still requires regular attention by the pool owner to remove and empty the leaf basket, sometimes several times a day (depending upon the volume of debris that might enter a particular pool from day-to-day). Indeed, when a leaf basket becomes full of debris it will become clogged and will prevent water flowing therethrough, which can cause basket rupture or damage to different parts of the skimming equipment and recirculating fluid system (pump and filters) due to restriction of fluid flow and increased pressure. This can cause starvation and thuscavitation of the pump in the recirculating system, noting that cavitation is a destructive force that can destroy pumps if left unattended.

[0005] Therefore, there is a need for a skimming system for swimming pools that permits a leaf basket to be emptied without requiring the pool owner to manually remove the leaf basket from a skimmer box for cleaning.

[0006] The above discussion of traditional systems, equipment and apparatus and the like is included in the specification for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priory date of each claim in this application.Summary of Invention

[0007] The present invention provides pool skimming apparatus including: a debris collection chamber having a pool-water inlet throat closable by a floating weir; a leaf basket fixed below the debris collection chamber, there being a return water outlet and a backflush water inlet below the leaf basket; and a backflush debris outlet above the debris collection chamber; whereby in normal operation, the pool water and debris will be drawn past the open floating weir and into the debris collection chamber, with debris being caught in the leaf basket and pool water passing to the return water outlet; and in backflush operation, water will enter the apparatus from the backflush water inlet below the leaf basket to pass upwardly through the leaf basket to force debris in the leaf basket up into the debris collection chamber, past the closed floating weir and out the backflush debris outlet.

[0008] In this broadest form of the invention, when in use, a skilled addressee will appreciate and understand that normal operation of the skimming apparatus will result in debris floating on the surface of the water in the pool being drawn into the debris collection chamber in the normal manner past a floating weir adapted to permit such floating debris to enter. Normally, that movement would be precipitated by theskimming apparatus being connected to a recirculating fluid system situated away from the pool which includes a pump (and usually one or more fine filters) for drawing pool water from the pool through a throat in the side wall of the pool and into the debris collection chamber. In the broadest form, such an arrangement is also envisaged for use with the skimming apparatus of the present invention.

[0009] However, when the skimming apparatus of the present invention is in its backflush operation, the apparatus does not operate conventionally but utilises an inventive arrangement of backflush inlets and outlets located relative to the leaf basket, with there being little or no movement of water from the pool through the poolwater throat and down through the leaf basket. Indeed, water will actually flow out from the backflush water inlet from below the leaf basket up through the leaf basket to dislodge debris retained therein, and will move that debris, with the flow of backflush water, past the closed floating weir (so that it does not return to the pool) and out of the skimming apparatus through the backflush debris outlet. The backflush debris outlet may then be in fluid communication with a collection sump or the like, for furthering filtering or separating debris and usable water, either for return to the pool or for other uses.

[0010] In a preferred form, the skimming apparatus also includes a deflector mounted within the skimming apparatus above the debris collection chamber, angled towards the backflush debris outlet so as to assist the flow of the backflush water into and out through the backflush debris outlet. In this respect, the normal configuration for a skimming apparatus adjacent a pool sees the normal pool water level ideally sitting at a point within the throat formed through the wall of the pool. This leaves an empty space within the skimming apparatus from the water level up to the level of the pool deck around the pool, where there is normally a skimming apparatus cover. The inclusion of the deflector at a level that is about at a normal pool water level within the skimming apparatus minimises the chances of cavitation above the water level (and within the skimming apparatus) resulting in debris being caught in that space and not passing through the backflush debris outlet.

[0011] In one form of deflector, the deflector may be a deflector plate, preferably transparent so that a pool owner can see the operational status of the system andalso see whether the leaf basket is full of debris or not. The deflector plate may be configured so as to be removable or pivotable as desired.

[0012] In relation to the leaf basket, it will be appreciated that, in backflush operation, and with a leaf basket reasonably clogged with debris, the backflush water may apply an amount of force to the leaf basket from below so as to dislodge the leaf basket if mounted in a traditional manner in the skimming apparatus. Such a traditional manner would see a leaf basket manually urged into a reasonably tight friction fit within an equivalently sized opening, so as to be retained in place at least against any buoyancy that the leaf basket might inherently have, but so as to be reasonably easily removed by hand when the time came to remove and clean the leaf basket (such as with a simple twist lock system).

[0013] In the present invention, and in light of the potential force that may be applied to the leaf basket from below, the leaf basket is preferably fixed in its position in the skimming apparatus below the debris collection chamber. Such fixing may be permanent but will preferably be temporary such that the leaf basket is still able to be removed by a pool owner if desired, such as for maintenance, repair or replacement, again such as by a simple twist lock system.

[0014] As mentioned above, in backflush operation water will exit the backflush water inlet below the leaf basket to pass upwardly through the leaf basket to force debris in the leaf basket up into the debris collection chamber, past the closed floating weir and out the backflush debris outlet. Backflush operation will of course not be the normal operating mode for the skimming apparatus of the present invention but will be a transitory operating mode. During this transitory mode, the floating weir will need to be closed, or at least substantially closed, such that minimal (or preferably no) debris passes out the throat past the weir and back into the pool.

[0015] In one form, the closing of the floating weir will preferably be achieved by the simple discontinuation of normal operation, and thus discontinuation of pool water and debris being drawn past the open (inclined nearly to horizontal) floating weir and into the debris collection chamber. With that water flow being discontinued, and backflush operation commencing such that water exits by whatever velocity (flow and pressure) is generated in the backflush system, from the backflush water inlet belowthe leaf basket to pass upwardly through the leaf basket, the floating weir will preferably automatically re-orient itself vertically such as to close and substantially prevent the passage of debris thereby.

[0016] In relation to the commencement of backflush operation, the flow of backflush water through the leaf basket from below may be initiated by a backflush pump incorporated in a recirculating fluid system situated away from the pool, which may be a separate pump to that used for normal operation or which may be the same pump as that used for normal operation, being suitably controlled and integrated in the recirculating fluid system so as to be able to function as both. In another version, a backflush pump may be provided in or near the skimming apparatus itself. In either version, the backflush pump will be in fluid communication with the backflush water inlet below the leaf basket.

[0017] In another form, the flow of backflush water through the leaf basket from below the leaf basket may be initiated by gravity and the storage of a suitable volume of backflush water in a surge tank. In this form, where no backflush pump is incorporated in the skimming apparatus of the present invention, the backflush water inlet will be a surge water inlet in fluid communication with a surge tank, there being suitable valving and control provided to release water from the surge tank when normal operation is discontinued and backflush operation commences. The period of backflush operation may then end once the surge tank is emptied, or sooner if lesser flow is required from the surge tank to dislodge debris from the leaf basket.

[0018] In this form, namely the use of a surge tank for the provision of backflush water, the skimming apparatus of the present invention will of course still require a normal pump for drawing pool water from the pool through the skimming apparatus (which will be referred to here as an operational pump). This operational pump may be incorporated in a recirculating fluid system situated away from the pool as normal, or may alternatively be near or integrated within the skimming apparatus, preferably being vertically integrated below the leaf basket.

[0019] In this preferred form, such a vertically-integrated operational pump, positioned below the leaf basket, will advantageously be as described in the applicant’s co-pending International patent application titled “An Axial-FlowCentrifugal Hydraulic Pump”, which may be the subject of a preferred control regime of the type described in the applicant’s co-pending International patent application titled “A Controller for Controlling Movement in an Aquatic Application”, both being lodged on the same day as this present application. The content of both of these copending patent applications is herein incorporated by reference.

[0020] The preferred vertically-integrated pump will be an axial-flow centrifugal hydraulic pump having an axially extending pump body (configured vertically) with an inlet at one end of the pump body (the top) and an outlet at an opposed end of the pump body (the bottom). The pump will preferably include a low voltage (under 30V DC) direct current (DC) electric motor housed centrally within the pump body between the inlet and the outlet and having a central rotating shaft, there ideally being a turbine impeller coupled to the DC electric motor, via the rotating shaft, adjacent the inlet and configured to rotate about an axis to pump water from the inlet towards the outlet within the pump body. In one form, the turbine impeller may have a plurality of impeller vanes. The pump may also include a diffuser mounted to the pump body adjacent the outlet, the diffuser having a plurality of diffuser vanes matched to the impeller vanes to produce a laminar flow of water at the outlet as the pumped water flows through the diffuser. Ideally, the diffuser vanes will extend axially at least partially over the DC electric motor, with the pumped water passing over the DC electric motor to cool and soundproof the DC electric motor when in use.

[0021] In this form, and with the pump vertically integrated below the leaf basket of the skimming apparatus, the pump will draw water down through the leaf basket during normal operation into the pump inlet, and the DC electric motor will be an Extra Low Voltage DC electric motor (namely, less than 30V DC).

[0022] An Extra Low Voltage DC electric motor can be submerged safely within the skimming apparatus, with pumped water passing over the DC electric motor to cool and soundproof the DC electric motor when in use. Further, as a pump of this preferred type has a small footprint, and does not have an external cooling fan, it can readily be installed underground, below water and thus below the leaf basket.

[0023] The diffuser vanes and the turbine impeller vanes of this preferred form of pump will ideally be equally spaced about the diffuser and the turbine impeller,respectively. The diffuser vanes will ideally be different in number than the turbine impeller vanes. For example, the diffuser may have seven diffuser vanes equally spaced about the diffuser with the turbine having eight turbine impeller vanes equally spaced about the turbine impeller. Such matching of the turbine impeller and diffuser minimises energy loss associated with converting mechanical energy, via a centrifugal impeller driven by an electric motor, to hydraulic energy of the pumped water. The preferred in-line design of axially aligned inlet and outlet for this preferred axial-flow centrifugal hydraulic pump also reduces energy losses associated with directional flow change of the pumped water as well as minimising pressure drop when compared to a radial-flow pump.

[0024] In another preferred form of the pump, each of the turbine impeller vanes may extend axially from the inlet and spirally from an eye of the impeller. Also, each of the diffuser vanes may extend axially and spirally from the pump outlet. The shape of the diffuser vanes thus preferably guides water off the impeller and provides a sweeping, gentle redirection of the water to create a laminar flow. The reduced turbulence of a laminar flow further reduces energy loss of the pump.

[0025] Ideally, the diffuser vanes will be adjacent the pump body and will extend radially towards the DC electric motor. As mentioned, the diffuser vanes extend at least partially over the DC electric motor so that pumped water passes over the DC electric motor in a laminar flow action to cool and soundproof the DC electric motor when in use. Typical centrifugal pumps, on the other hand, require a supplementary external air fan for motor cooling, which is noisy and requires additional power.

[0026] Additionally, the turbine impeller vanes preferably extend radially from adjacent the rotating shaft of the DC electric motor towards the pump body, with the diameter of the turbine impeller preferably being within a width of the diffuser vanes. That is, preferred form of axial-flow centrifugal pump for use, with its in-line design, is a compact design that allows for the diameter of the impeller to be close to the diameter of the pump body which improves water flow relative to the size of the pump.

[0027] The rotating shaft will preferably have a conical cap adjacent the inlet configured to provide water to an eye of the impeller at an angle to the axis. The conical cap or cone induces less turbulence of the water entering the eye of theimpeller. In particular, the angle to which the water enters the eye of the impeller is not 90 degrees to the exit of the impeller as per radial impellers. For example, the angle to the axis which the water enters the eye of the impeller is between 40 and 50 degrees (e.g. 40 degrees). This angle reduces the directional change of the water in the impeller and thus reduces energy loss. Further, the conical cap is preferably made of a non-corrosive, non-ferrous metal and acts as a heat sink to transfer heat from the rotating shaft to the water provided to the eye of the impeller.

[0028] In another form, a pump vertically integrated below the leaf basket may be a reversible pump / motor such that it is capable of functioning during normal operation to draw water from the pool through the throat, past the floating weir and down through the leaf basket, and separately during backflush operation to draw water from the discharge water outlet up through the leaf basket from below to dislodge and remove debris from the leaf basket. In this form, there would therefore be no essential need for the skimming apparatus to include a surge tank to provide the backflush water. In this embodiment, the return-to-pool (RTP) outlets will preferably be below water level, and any filters adopted adjacent to the skimming apparatus will preferably be cartridge filters below water level, as will be described below. In such a configuration, there is the additional benefit of fine debris being partially removed (via reverse velocity) from the filter cartridge element, thus assisting to further extend the filtration life of the cartridge element.

[0029] In relation to the backflush operation, it will be understood that the skimming apparatus of the present invention may rely on and include both a backflush pump and a surge tank, with appropriate connections and controls, such that a pool owner may select either option for the backflush operation. There may be situations where it is advantageous to utilise the simplicity and presumably lower energy consumption of a surge tank, in preference to operating a backflush pump, such as in situations where a surge tank can be opened manually by a pool owner during, for example, a power outage. In the alternative, assuming a surge tank to contain a finite amount of surge water for one backflush operation, it may be necessary to operate a backflush pump for a longer period of time, to ensure complete cleaning of a leaf basket, than would be possible for a surge tank of reasonable size.Brief Description of Drawings

[0030] Embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings, in which:

[0031] Figure 1 a is a sectional view of pool skimming apparatus to an embodiment of the present invention;

[0032] Figure 1 b is an exploded sectional view of the pump 19 of Figure 1 a;

[0033] Figures 2a, 2b and 2c are isometric, top and side views of pool skimming apparatus in accordance with the embodiment of Figure 1 , but in association with pool filtration equipment; and

[0034] Figure 3 is a schematic view of the embodiment of Figure 1 , but in association with a surge tank.Detailed Description of Preferred Embodiment

[0035] An embodiment of pool skimming apparatus 10 in accordance with the present invention is shown in Figure 1 a. The apparatus 10 includes a debris collection chamber 12 having a pool-water inlet throat 14 closable by a floating weir 16. There is a leaf basket 18 fixed below the debris collection chamber 12 and an operational pump 19 vertically integrated below the leaf basket 18, with a backflush water inlet 22 also below the leaf basket 18, a return water outlet 20 below the operational pump 19, and a backflush debris outlet 24 above the debris collection chamber 12.

[0036] In normal operation, pool water and debris (not shown) will be drawn past the open floating weir 16 (shown open in Figure 1 a) and into the debris collection chamber 12, with debris being caught in the leaf basket 18 and pool water passing to the return water outlet 20 by virtue of the operational pump 19. In backflush operation, water will enter the apparatus 10 from the backflush water inlet 22 below the leaf basket 18 to pass upwardly through the leaf basket 18 to force debris (again not shown) in the leaf basket 18 up into the debris collection chamber 12, past the now closed floating weir 16 (albeit shown in Figure 1 a in its open position) and out the backflush debris outlet 24.

[0037] The skimming apparatus 10 also includes a deflector 30 mounted within the apparatus 10 above the debris collection chamber 12, angled towards the backflush debris outlet 24 so as to assist the flow of the backflush water into and out through the backflush debris outlet 24. The deflector 30 also assists with preventing the rising backflush water from hitting and possibly lifting the cover 32.

[0038] The normal configuration for skimming apparatus adjacent a pool sees the normal pool water level ideally sitting at a point within the throat 14 formed through the wall of the pool, for example at about the broken line A-A in Figure 1 a. This leaves an empty space within the skimming apparatus from the water level up to the level of the pool deck around the pool (see the broken line B-B in Figure 1 a), where there is the cover 32. The inclusion of the deflector 30 at a level that is about level with the top of the backflush debris outlet 24 within the apparatus 10 minimises the chances of cavitation above the water level (and within the apparatus 10) during backflush operation resulting in debris being caught in that space and not passing through the backflush debris outlet 24.

[0039] In this embodiment, the deflector 30 is a transparent plate, transparent so that a pool owner can see the operational status of the system and also see whether the leaf basket 18 is full of debris or not. The deflector 30 is configured so as to be removable and is preferably held in place via a simple twist lock mechanism (not shown), using four locating tabs and slots. A suitably sized moulded handle can be provided for ease of removal and replacement. The tabs may be positioned in such a way that the deflector 30 can only be repositioned in the correct orientation.

[0040] The leaf basket 18 is fixed in its position below the debris collection chamber 12 in a temporary manner such that the leaf basket 18 is still able to be removed by a pool owner if desired, such as for maintenance, repair or replacement. The leaf basket can also be held in place via a simple twist lock mechanism, again using four locating tabs and slots. A suitably sized moulded handle can again be provided for ease of removal and replacement, although in this instance the orientation is not as important and thus all four twist lock tabs can be equally positioned.

[0041] In relation to the commencement of backflush operation, the flow of backflush water through the leaf basket from below may be initiated by a backflush pump (not shown) incorporated in a recirculating fluid system (also not shown) situated away from the pool, which may be a separate pump to that used for normal operation or which may be the same pump as that used for normal operation, being suitably controlled and integrated in the recirculating fluid system so as to be able to function as both. Such a backflush pump would be in fluid communication with the backflush water inlet 22 below the leaf basket 18 such that water will enter the apparatus 10 from the backflush water inlet 22 to pass upwardly through the leaf basket 18, with the velocity of the water being sufficient to force debris in the leaf basket 18 up into the debris collection chamber 12, past the closed floating weir 16 and out the backflush debris outlet 24.

[0042] However, in this embodiment, the flow of backflush water through the leaf basket 18 from below the leaf basket 18 is initiated by gravity and the storage of a suitable volume of backflush water in a surge tank 50 (see Figure 3). In this form, the backflush water inlet 22 is actually a surge water inlet in fluid communication with the surge tank 50, there being suitable valving 52 and control provided to release water from the surge tank 50 when normal operation is discontinued and backflush operation commences. This operation can be controlled automatically via an incorporated and integral control system (not shown). In this embodiment, the system can ideally sense the leaf basket 18 is full (blocked) and can stop the pump from its normal filtration cycle. The system can then commence a backflush cycle using the surge tank 50 and its valving 52, which can be timed or can simply be based on the predetermined volume of the surge tank 50, then an automated controller can revert the pump back to its normal filtration cycle and the surge tank can be permitted to refill. In this respect, predetermined electrical parameters can be adopted to determine if the leaf basket has been successfully backflushed (unblocked).

[0043] In relation to the operational pump 19 in this embodiment, and as better illustrated in Figure 1 b, the pump 19 includes an axially extending pump body 60 having an inlet 62 at one end (the top) of the pump body 60 and an outlet 64 at an opposed end (the bottom) of the pump body 60. The pump body 60 is cylindrical in shape and houses a cylindrically shaped low voltage direct current (DC) electric motor 66 centrally within the pump body 60 between the inlet 62 and the outlet 64 of thepump 19. The vertically positioned pump 19 locates on a fixed discharge plate at the bottom and a removable (twist lock) plate at the top. This allows for service / removal of the pump 19, after removing both the deflector plate 30 and leaf basket 18. The direction of water flow through the pump 19 is shown via the arrows 68 in Figure 1 b.

[0044] As mentioned, the DC electric motor 66 is preferably an Extra Low Voltage (ELV) DC electric motor. In particular, the ELV DC electric motor 66 operates at typically less than 30V ripple-free DC so that the motor 66 can be submerged safely within water from the swimming pool and within the pump body 60 (as per AS3000 Wiring rules, zone “O” classification). The ELV motor 66 may have a power range of 100-800 Watts and it used to rotate a central rotating shaft 70 housed within a waterproof motor body.

[0045] Typically, an AC electric motor for an axial-flow or radial-flow centrifugal pool pump operates on 2 poles at 3000 rpm for 240V 50Hz countries and 3600 rpm for 110V 60Hz countries. In the embodiment, the ELV DC motor 66 operates at lower speeds of around 2000-2400 rpm, with an operational design speed range of between 1000 and 2800 rpm. These reduced pump speeds have a number of design advantages, including lower energy use and reduced noise.

[0046] The pump 19 further includes a turbine impeller 72 coupled to the DC electric motor 66, via the rotating shaft 70, adjacent the inlet 62. The turbine impeller 72 is configured to rotate about an axis to pump water from the inlet 62 towards the outlet 64 axially within the pump body 60. The turbine impeller 72 has a plurality of impeller vanes 74 that are equally spaced about the turbine impeller 72 to pump the water.

[0047] Each of the turbine impeller vanes 74 extend axially from the inlet 62 and spirally from an eye of the impeller 72. The turbine impeller 72 also includes a back plate at an angle to the axis and the turbine impeller vanes 74 extend axially from the back plate. The turbine impeller vanes 74 also extend radially from adjacent the rotating shaft 70 of the DC electric motor 66 towards the pump body 60.

[0048] The pump 19 further includes a diffuser 80 mounted to the pump body 60 adjacent the outlet 64. The diffuser 80 includes a plurality of diffuser vanes 82 that are matched to the impeller vanes 74 to produce a laminar flow of water at the outlet64 as the pumped water flows through the diffuser 80. The diffuser vanes 82 extend axially partially over the DC electric motor 66 and the pumped water passes over the DC electric motor 66 to cool and soundproof the DC electric motor 66 when in use.

[0049] As mentioned, the operational design speed range of the DC electric motor 66 is between 1000 and 2800 rpm, which is optimal for the turbine impeller 72 for greater flow characteristics. In an embodiment, the DC electric motor 66 is a High Efficiency Brushless Permanent Magnet DC Electric motor (BLDC), and thus speed control is native DC to DC via a motor controller (not shown). Further, the pump 19 includes a DC power supply (not shown) for the DC electric motor 66. The DC electric motor 66 can also be powered by one or more photovoltaic panels and or by a battery (not shown). Both are natively DC, therefore as power is not required to be inverted from AC to DC and then back to AC as a “chopped” sinewave, the motor controller generates less heat and is therefore more efficient (e.g. in the 98-99% range).

[0050] The diffuser vanes 82 are equally spaced about the diffuser 80. The diffuser vanes 82 are different in number than the turbine impeller vanes 74 and, in the embodiment, there are eight turbine impeller vanes 74 and seven diffuser vanes 82. This ensures that the impeller vanes 74 can never line up exactly with the diffusor vanes 82 when rotating, avoiding the possibility of a pulse occurring while the pump 19 is operating which can lead to undesired vibration for the pump 19.

[0051] The turbine impeller 72 is matched to the diffuser 80 to produce laminar flow and less turbulent swirl, and thus less energy loss through the pump 19. In the embodiment, the angles of the eight turbine impeller vanes 74 are matched to the angles of the seven diffuser vanes 82 to produce the laminar flow of water through the pump 19.

[0052] More specially, each of the diffuser vanes 82 extend axially and spirally from the outlet 64 of the pump 19. The diffuser vanes 82 are also adjacent the pump body 60, via a lip or seal that is not shown, and extend radially towards the body of the DC electric motor 66. The lip or seal helps to reduce recirculation of water in the pump. The diameter of the turbine impeller 72 is thus within a width of the diffuser vanes 82 for maximised throughput of water through the pump 19. That is, a largerimpeller diameter can be used in the pump 19 relative to the diameter of the pump body than can be employed with radial impellers which must be positioned outside the diameter of the impeller.

[0053] The diffuser vanes 82 are angle or spiralled in such a way that once the water exits the impeller 72, the vanes 82 gently redirect the flow of water over the motor 66 and out of the outlet 64 of the pump 19 in a laminar flow motion without significant turbulence.

[0054] The turbine impeller 72 is coupled to the rotating shaft 70 of the DC electric motor 66 via a replaceable wear ring 84 having a peripheral wear surface. The wear ring 84 has a double purpose. The first is to take any wear over time, such as from the presence of abrasive sand in the water. The wear ring 84 is replaceable and thus can simply be replaced if and when the tolerances between the impeller 72 and the wear ring 84 become too great which would result in a loss of performance of the pump 19. The second purpose is to operate as an anti-recirculation device.

[0055] The peripheral wear surface of the wear ring 84 includes three, stepped surfaces to form a torturous path for water in the pump body 60 not in the impeller to reduce circulation of water back towards the inlet 62. The first stepped surface forms a first labyrinth seal 86, the second stepped surface forms a second labyrinth seal 88 and a third labyrinth seal 90, and the third stepped surface forms a fourth labyrinth seal 92 and a fifth labyrinth seal 94. When water from the pressure side tries to get back into the low-pressure suction side, water can recirculate inside the pump rather than being pumped out through the resistive pipework. The wear ring 84 provides a torturous path for the water to reduce recirculation and improve efficiency of the pump 19.

[0056] In relation to the three drawings of Figures 2a, 2b and 2c, the skimming apparatus 10 of Figure 1 is shown in a preferred configuration in fluid communication with dual cartridge filters 100. The apparatus 10 includes the debris collection chamber 12 having a pool-water inlet throat 14, with the operational pump 19 vertically integrated below debris collection chamber 12 and the leaf basket (not visible), with return water outlets 20 below the operational pump 19 in fluid communication with respective cartridge filters 100, and the backflush debris outlet 24above the debris collection chamber 12. The operational pump 19 is show as being in fluid communication with respective cartridge filters 100 via 90-degree elbow pipes. Alternatively, the cartridge filters 100 are adjacent the operational pump 19 and connected via straight pipes. It is envisaged that a compact arrangement of this type, possible due to the vertical integration of the pump 19, will be desirable for use by pool owners such that the entire pump, backflush and filtration systems may be incorporated together and underground.

[0057] In this form, no dedicated plantroom is required and no pipework needs to be exposed. Indeed, as can be seen from the schematic diagram of Figure 3, which shows the skimming apparatus 10 of Figure 1 in the preferred configuration in fluid communication with dual cartridge filters 100, all positioned underneath a pool deck 140 and adjacent a pool 142. In Figure 3, the preferred arrangement of the flow of backflush water through the leaf basket 18 from below the leaf basket 18 initiated by gravity and the storage of a suitable volume of backflush water in a surge tank 50 is illustrated. In this form, the backflush water inlet 22 is actually a surge water inlet in fluid communication with the surge tank 50, there being suitable valving 52 and control provided to release water from the surge tank 50 when normal operation is discontinued and backflush operation commences, with that water entering via the backflush water inlet 22.

[0058] It is to be understood that various alterations, additions and / or modification may be made to the parts previously described with departing from the ambit of the present invention.

Claims

The claims defining the invention are as follows:1 . Pool skimming apparatus including: a debris collection chamber having a pool-water inlet throat closable by a floating weir; a leaf basket fixed below the debris collection chamber, there being a return water outlet and a backflush water inlet below the leaf basket; and a backflush debris outlet above the debris collection chamber; whereby in normal operation, the pool water and debris will be drawn past the open floating weir and into the debris collection chamber, with debris being caught in the leaf basket and pool water passing to the return water outlet; and in backflush operation, water will enter the apparatus from the backflush water inlet below the leaf basket to pass upwardly through the leaf basket to force debris in the leaf basket up into the debris collection chamber, past the closed floating weir and out the backflush debris outlet.

2. Pool skimming apparatus according to claim 1 , wherein the backflush debris outlet is in fluid communication with a collection sump for filtering or separating debris and usable water.

3. Pool skimming apparatus according to claim 1 or claim 2, including a deflector mounted within the skimming apparatus above the debris collection chamber, angled towards the backflush debris outlet so as to assist the flow of the backflush water into and out through the backflush debris outlet.

4. Pool skimming apparatus according to claim 3, wherein the deflector is a deflector plate configured so as to be removable or pivotable.

5. Pool skimming apparatus according to any one of claims 1 to 4, wherein the leaf basket is fixed in position in the skimming apparatus below the debris collection chamber.

6. Pool skimming apparatus according to claim 5 wherein the fixing of the leaf basket is temporary such that the leaf basket is still able to be removed.

7. Pool skimming apparatus according to any one of claims 1 to 6, including a backflush pump incorporated in the pool skimming apparatus in fluid communication with the backflush water inlet below the leaf basket.

8. Pool skimming apparatus according to claim 7, wherein the backflush pump is vertically integrated in the skimming apparatus below the leaf basket.

9. Pool skimming apparatus according to any one of claims 1 to 8, including a surge tank for storage of water, the backflush water inlet thus being a surge water inlet in fluid communication with the surge tank, the surge tank including valving that permits, when normal operation is discontinued and backflush operation commences, the surge water to empty from the surge tank through the surge water inlet through the leaf basket from below to dislodge debris from the leaf basket.

10. Pool skimming apparatus according to claim 7 or claim 9, including an operational pump for drawing pool water from the pool through the skimming apparatus.11 . Pool skimming apparatus according to claim 10, wherein the operational pump is vertically integrated below the leaf basket.

12. Pool skimming apparatus according to claim 11 , wherein the operational pump is an axial-flow centrifugal hydraulic pump having an axially extending pump body (configured vertically) with an inlet at one end of the pump body (the top) and an outlet at an opposed end of the pump body (the bottom).

13. Pool skimming apparatus according to claim 12, wherein the axially extending pump body has a top end and a bottom end and is configured vertically with an inlet at the top end and an outlet at the bottom end.

14. Pool skimming apparatus according to claim 13, wherein the operational pump includes a low voltage direct current (DC) electric motor housed centrally within the pump body between the inlet and the outlet, having a central rotating shaft, there being a turbine impeller coupled to the DC electric motor, via the rotating shaft, adjacent the inlet and configured to rotate about an axis to pump water from the inlet towards the outlet within the pump body.

15. Pool skimming apparatus according to claim 14, wherein the operational pump includes a diffuser mounted to the pump body adjacent the outlet, the diffuser having a plurality of diffuser vanes matched to a plurality of impeller vanes to produce a laminar flow of water at the outlet as the pumped water flows through the diffuser.

16. Pool skimming apparatus according to claim 15, wherein the diffuser vanes extend axially at least partially over the DC electric motor, with the pumped water passing over the DC electric motor to cool and soundproof the DC electric motor when in use.

17. Pool skimming apparatus according to claim 10 to 16, wherein the operational pump is a reversible pump such that it is capable of functioning during normal operation to draw water from the pool through the throat, past the floating weir and down through the leaf basket, and separately during backflush operation to draw water from the backflush water inlet up through the leaf basket from below to dislodge and remove debris from the leaf basket.

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