TECHNICAL FIELD

The present disclosure relates to filter apparatus. More particularly, but not exclusively, the present disclosure relates to filter apparatus for performing filtration of a liquid. The filter apparatus and method may be suitable for filtering water in aquariums. Alternatively, or in addition, the filter apparatus may be suitable for filtering water in ponds, aqua-culture, swimming pools, swimming baths, swimming ponds, leisure pools, hot tubs, spas and leisure parks. BACKGROUND

It is known to provide a filter apparatus for filtering a liquid, such as water, to remove debris. A filter media, such as sand, may be provided in a filter chamber. The supply of the unfiltered water to the filter chamber and the return of the filtered water is controlled by a series of valves. In order to provide automated or semi-automated operation, one or more of the valves may comprise an actuator, such as a solenoid actuator. This increases the complexity of the filter apparatus and the associated cost.

At least in certain embodiments, the filter apparatus described herein seeks to overcome at least some of the problems associated with the prior art.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a filter apparatus as claimed in the appended claims.

According to a further aspect of the present invention there is provided a filter apparatus for filtering a liquid, the filter apparatus comprising:

a filter chamber having an inlet and an outlet;

a drain for draining liquid from the filter chamber;

an inlet valve assembly for selectively opening and closing the inlet, the inlet valve assembly comprising an inlet valve member movable between a closed position and an open position; and

a drain valve assembly for selectively opening and closing the drain, the drain valve assembly comprising a drain valve member movable between a closed position and an open position;

wherein the inlet valve member is coupled to the drain valve member. By coupling the drain valve member to the inlet valve member, the opening and closing of the drain valve member may be performed in unison with the inlet valve member. This may facilitate control of the filter apparatus. The inlet valve member may be coupled to the drain valve member such that the drain valve member is displaced to the closed position in dependence on the inlet valve member being displaced to the open position. The inlet valve member may, for example, rotate, pivot or translate between the closed position and the open position.

The coupling provided between the inlet valve member and the drain valve member may be configured such that the drain valve member is displaced to the closed position in dependence on the inlet valve member being displaced to the open position. Conversely, the drain valve member may be displaced to the open position in dependence on the inlet valve member being displaced to the closed position.

The inlet valve member may be coupled to the drain valve member such that the drain valve member is displaced to the open position in dependence on the inlet valve member being displaced to the closed position.

The inlet valve member and the drain valve member may be configured such that, when the inlet valve member is in the open position, the drain valve member is in the closed position. Conversely, when the inlet valve member is in the closed position, the drain valve member may be in the open position.

The drain valve member could be biased towards the closed position. Alternatively, the drain valve member may be biased towards the open position.

The drain valve member may be biased by spring biasing means. The drain valve member may be biased under the action of gravity. The drain valve member may be biased by a buoyant element, such as a float. The inlet valve member could be biased towards the open position. Alternatively, the inlet valve member may be biased towards the closed position.

The inlet valve member may be biased by spring biasing means. The inlet valve member may be biased towards the closed position under the action of gravity. The inlet valve member may be biased by a buoyant element, such as a float.

The inlet valve assembly may be operable in dependence on a hydraulic pressure of the liquid supplied to the filter apparatus. The inlet valve assembly may be operated in dependence on a hydraulic pressure of the liquid supplied to the filter apparatus. At least in certain embodiments, the inlet valve assembly may be controlled by controlling the supply of liquid to the filter apparatus. For example, the inlet valve assembly may be controlled in dependence on operation of a pump for supplying liquid to the filter apparatus. The pump may be activated to supply liquid to the filter apparatus and the inlet valve assembly may open in dependence on the resulting increase in the hydraulic pressure of the liquid. The pump may be de-activated so as to stop the supply of liquid to the filter apparatus and the inlet valve assembly may close in dependence on the reduction in the hydraulic pressure of the liquid. Thus, at least in certain embodiments the filter apparatus may be controlled in dependence on operation of the pump. The need to provide an actuator for one or more of the valve assembly may be reduced or avoided. This may simplify the filter apparatus and the operation of the filter apparatus. For example, the filter apparatus may be configured to operate in a filtration mode when the pump is operating; and in a backwashing mode when the pump is not operating. The operation of the filter apparatus may be automated or partially automated in dependence on operation of the pump. At least in certain embodiments, the filter apparatus may be a pump-controlled filter apparatus.

According to a further aspect of the present invention there is provided a filter apparatus for filtering a liquid, the filter apparatus comprising:

a filter chamber having an inlet and an outlet;

a drain for draining liquid from the filter chamber;

an inlet valve assembly for selectively opening and closing the inlet, the inlet valve assembly comprising an inlet valve member movable between a closed position and an open position; and

a drain valve assembly for selectively opening and closing the drain, the drain valve assembly comprising a drain valve member movable between a closed position and an open position;

wherein the inlet valve assembly is operated in dependence on a hydraulic pressure of the liquid supplied to the filter apparatus. At least in certain embodiments, the inlet valve assembly may be controlled in dependence on operation of a pump for supplying liquid to the filter apparatus.

The filter apparatus may comprise a pump. Alternatively, the filter apparatus may be configured to be connected to a pump. For example, the filter apparatus may comprise a connector or a coupling for connecting the filter apparatus to the pump. The pump may be provided upstream of the filter apparatus and configured to pump water to the filter chamber. When the pump is operating, the hydraulic pressure in the filter chamber may be greater than atmospheric pressure. The pump may be provided downstream of the filter apparatus and configured to draw water into the filter chamber. When the pump is operating, the hydraulic pressure in the filter chamber may be less than atmospheric pressure.

The inlet valve member may be displaced to the open position when the pressure of the liquid downstream of the inlet valve member is less than the pressure of the liquid upstream of the inlet valve member. The inlet valve member may be displaced to the closed position when the pressure of the liquid in the filter chamber is less than the pressure of the liquid upstream of the inlet valve member. The pressure of the liquid downstream of the inlet valve member may correspond to the operating pressure in the filter chamber. The pressure of the liquid upstream of the inlet valve member may correspond to the pressure in the supply conduit.

The inlet valve member may be coupled to the drain valve member by a coupling member. The coupling member may comprise a rod. The coupling member could be a flexible element, such as a chain, for transmitting a tensile force.

The inlet valve member and the drain valve member may be formed separately from each other. Alternatively, the inlet valve member and the drain valve member may be formed integrally. The inlet valve member and the drain valve member may be formed on opposing sides of a valve element.

The valve element may be movable selectively to move the inlet valve member and the drain valve member between the respective open and closed positions. The valve element may be pivotable selectively to move the inlet valve member and the drain valve member between the respective open and closed positions. The valve element may be translatable selectively to move the inlet valve member and the drain valve member between the respective open and closed positions.

The inlet valve member and the drain valve member may be coupled to each other by a piston.

The inlet valve assembly may comprise a one-way (check) valve; and/or the drain valve assembly may comprise a one-way (check) valve. The filter apparatus may be configured for operating at pressures greater than atmospheric pressure; and/or pressures less than atmospheric pressure. The filter chamber may be a sealed chamber. The filter apparatus may comprise means for introducing air into the filter chamber. The air introducing means may comprise an air supply conduit having at least one air inlet for introducing air into the filter chamber.

The air supply conduit may be in fluid communication with the liquid outlet. The air supply conduit may be connected to a conduit downstream of the outlet valve.

The filter apparatus may comprise an air supply valve assembly for controlling the introduction of air into the filter chamber through the air supply conduit. The air supply valve assembly may comprise an air supply valve member movable between a closed position and an open position.

The air supply valve member may be coupled to the inlet valve member.

The air supply valve member may be coupled to the inlet valve member such that the air supply valve member is displaced to the open position in dependence on the inlet valve member being displaced to the closed position. The air supply valve member may be coupled to the inlet valve member such that the air supply valve member is displaced to the closed position in dependence on the inlet valve member being displaced to the open position.

The filter apparatus may comprise an outlet valve assembly for selectively opening and closing the outlet. The outlet valve assembly may comprise an outlet valve member movable between a closed position and an open position. The outlet valve member may, for example, rotate, pivot or translate between the closed position and the open position.

The outlet valve member may be biased towards the closed position.

The inlet valve assembly may comprise a one-way (check) valve.

The outlet valve member may be coupled to the drain valve member. At least in certain embodiments, the outlet valve member may be coupled to both the drain valve member and the inlet valve member. The outlet valve member and the drain valve member may be formed integrally. The outlet valve member and the drain valve member may be formed on opposing sides of a valve element. The filter apparatus may comprise a pump. Alternatively, the filter apparatus may be configured to connect to a pump.

The filter apparatus may be configurable selectively to perform filtration and backwashing. The filter apparatus described herein has particular application when the flow rate of the liquid through the filter chamber is relatively high. When operating at a high flow rate, the hydrodynamic forces acting on the inlet valve member are suitable for opening the inlet valve and maintaining the inlet valve open during filtration. The filter apparatus described herein is suitable for use with filter elements having an open cell structure since this typically allows a higher flow rate through the filter chamber.

During filtration, the filter apparatus may be configured to establish a flow rate per unit cross- sectional area of the static filter pack greater than 10m ³ /m ² /h. During filtration, the filter apparatus may be configured to establish a flow rate per unit cross-sectional area of the static filter pack greater than 30m ³ /m ² /h. During filtration, the filter apparatus may be configured to establish a flow rate per unit cross-sectional area of the static filter pack greater than 60m ³ /m ² /h. The cross-sectional area of the static filter pack may correspond to the cross-sectional area of the filter chamber (for example in a direction perpendicular to the primary flow direction of the liquid through the filter chamber).

According to a further aspect of the present invention there is provided a filter apparatus comprising:

a filter chamber comprising a plurality of mechanical filter elements for forming a static filter pack to perform mechanical filtration of a liquid;

the filter apparatus is configured to generate a flow of the liquid through the mechanical filter elements during filtration.

The filter chamber may have an inlet and an outlet. The filter apparatus may comprise an inlet valve assembly for selectively opening and closing the inlet. The inlet valve assembly may comprise an inlet valve member movable between a closed position and an open position. The filter chamber may comprise a drain. A drain valve assembly may be provided for selectively opening and closing the drain. The drain valve assembly may comprise a drain valve member movable between a closed position and an open position. The inlet valve member may be coupled to the drain valve member.

The filter apparatus may comprise means for introducing air into the filter chamber through one or more air inlets to agitate the filter elements. The filter chamber may be substantially sealed and the air introducing means may be configured to draw air into the filter chamber as liquid is drained from said filter chamber.

The filter elements may each have an open cell structure. Each filter element may comprise one or more open cells. The filter elements may form a static filter pack in the filter chamber to mechanically filter the liquid. It has been recognised that the open cell structure of the filter elements enables effective filtration to be performed at higher flow speeds (i.e. flow rate per unit cross-sectional area) than known filters, such as sand bed filters. By increasing the flow rate per unit cross-sectional area of the static filter pack, the cross-sectional area of the filter apparatus may be reduced while maintaining the flow rate through the filter pack. Thus, at least in certain embodiments, the size of the filter apparatus may be reduced compared to prior art systems.

The flow rate per unit cross-sectional area of the static filter pack is expressed in units of m ³ /m ² /h (i.e. the volume of liquid (m ³ ) for a given cross-sectional area of the filter (m ² ) per hour (h)). The flow rate per unit cross-sectional area of the static filter pack corresponds to the volumetric flow rate through the static filter pack. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack is greater than 10m ³ /m ² /h, 20m ³ /m ² /h, 30m ³ /m ² /h, 40m ³ /m ² /h, 50m ³ /m ² /h 60m ³ /m ² /h, 65m ³ /m ² /h, 70m ³ /m ² /h or 100m ³ /m ² /h. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 550m ³ /m ² /h exclusive. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 150m ³ /m ² /h exclusive. At least in certain embodiments, the filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack in the range 150m ³ /m ² /h to 550m ³ /m ² /h; or 200m ³ /m ² /h to 500m ³ /m ² /h; or 250m ³ /m ² /h to 450m ³ /m ² /h; or 300m ³ /m ² /h to 400m ³ /m ² /h; or 325m ³ /m ² /h to 375m ³ /m ² /h. The filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack of approximately 350m ³ /m ² /h. The filter apparatus is operable to perform filtration and backwashing. The backwashing may comprise draining the water in the filter chamber through a waste outlet. The filter apparatus may comprise means for introducing air into the filter chamber through one or more air inlets to agitate the filter elements during backwashing. In certain embodiments, the filter chamber may be substantially sealed and the air introducing means may be configured to draw air into the filter chamber as liquid is drained from said filter chamber. The relatively small volume of the filter chamber of the filter apparatus described herein is advantageous since the volume of water sent to waste during backwashing cycle is relatively small. Thus, the frequency with which backwashing is performed may be increased compared to prior art filters.

A backwashing schedule may be implemented automatically by an electronic control unit (ECU) configured to control the filter apparatus. The ECU may, for example, control one or more of the following: a drain valve actuator, an inlet valve actuator, an outlet valve actuator, and a check valve actuator. The ECU may be configured to control the filter apparatus to perform filtration and backwashing. To perform filtration, the ECU may be configured to control the drain valve actuator to close the drain valve; and/or the inlet valve actuator to open the inlet valve; and/or the outlet valve actuator to open the outlet valve. To perform backwashing, the ECU may be configured to control the drain valve actuator to open the drain valve; and/or the inlet valve actuator to close the liquid inlet; and/or the outlet valve actuator to close the liquid outlet.

The filter elements may have substantially neutral buoyancy, negative buoyancy or positive buoyancy.

According to a further aspect of the present invention there is provided a filter apparatus for mechanically filtering a liquid, the filter apparatus comprising:

a filter chamber for containing a plurality of filter elements that form a filter pack for filtering the liquid, the filter chamber comprising a liquid inlet and a liquid outlet; and

means for introducing air into the filter chamber through one or more air inlets to agitate the filter elements, the filter chamber being substantially sealed and the air introducing means being configured to draw air into the filter chamber as liquid is drained from said filter chamber.

The means for introducing air into the filter chamber may comprise an air supply conduit having at least one air inlet for introducing air into the filter chamber. The air supply conduit may be disposed inside said filter chamber. For example, the air supply conduit may extend downwardly from said liquid outlet. The air supply conduit may extend substantially vertically within the filter chamber. The filter chamber may have an inlet and an outlet. The filter apparatus may comprise an inlet valve assembly for selectively opening and closing the inlet. The inlet valve assembly may comprise an inlet valve member movable between a closed position and an open position. The filter chamber may comprise a drain. A drain valve assembly may be provided for selectively opening and closing the drain. The drain valve assembly may comprise a drain valve member movable between a closed position and an open position.

The inlet valve member may be coupled to the drain valve member.

The flow rate per unit cross-sectional area of the static filter pack is expressed in units of m ³ /m ² /h (i.e. the volume of liquid (m ³ ) for a given cross-sectional area of the filter (m ² ) per hour (h)). The flow rate per unit cross-sectional area of the static filter pack corresponds to the volumetric flow rate through the static filter pack. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack is greater than 10m ³ /m ² /h, 20m ³ /m ² /h, 30m ³ /m ² /h, 40m ³ /m ² /h, 50m ³ /m ² /h 60m ³ /m ² /h, 65m ³ /m ² /h, 70m ³ /m ² /h or 100m ³ /m ² /h. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 550m ³ /m ² /h exclusive. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 150m ³ /m ² /h exclusive. At least in certain embodiments, the filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack in the range 150m ³ /m ² /h to 550m ³ /m ² /h; or 200m ³ /m ² /h to 500m ³ /m ² /h; or 250m ³ /m ² /h to 450m ³ /m ² /h; or 300m ³ /m ² /h to 400m ³ /m ² /h; or 325m ³ /m ² /h to 375m ³ /m ² /h. The filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack of approximately 350m ³ /m ² /h.

By increasing the flow rate per unit cross-sectional area of the static filter pack the cross- sectional area of the filter apparatus may be reduced whilst maintaining the flow rate (litres/hour) through filter apparatus. Thus, the overall dimensions of the filter apparatus may be reduced compared to known filter apparatus which use sand to perform filtration. It is believed that the operation of the filter apparatus at higher flow rates, for example greater than 60m ³ /m ² /h, 65m ³ /m ² /h, 70m ³ /m ² /h, 80m ³ /m ² /h, 90 m ³ /m ² /h or 100m ³ /m ² /h, is patentable independently.

At higher flow speeds, the filter elements may be displaced to form the static filter pack irrespective of the flow direction and/or buoyancy of the filter elements. For example, a down flow of liquid may form a static filter pack even if the filter elements have positive buoyancy. Conversely, an up flow of liquid may form a static filter pack even if the filter elements have negative buoyancy. The break-up of the static filter back may be expedited in these scenarios if the flow through the filter chamber is stopped to perform backwashing. The mechanical filter elements may comprise mechanical filter elements having one or more filter cell. The one or more filter cell can have at least a first cell opening. The mechanical filter elements may be of the type described herein.

According to a further aspect of the present invention there is provided a method of operating a filter apparatus of the type described herein. The inlet valve assembly may be operated in dependence on a hydraulic pressure of the liquid supplied to the filter apparatus. At least in certain embodiments, the inlet valve assembly may be controlled by controlling the supply of liquid to the filter apparatus. For example, the inlet valve assembly may be controlled in dependence on operation of a pump for supplying liquid to the filter apparatus. The method may comprise controlling operation of the pump to control the supply of liquid to the filter apparatus. The pump may be activated to supply liquid to the filter apparatus and the inlet valve assembly may open in dependence on the resulting increase in the hydraulic pressure of the liquid. The pump may be de-activated so as to stop the supply of liquid to the filter apparatus and the inlet valve assembly may close in dependence on the reduction in the hydraulic pressure of the liquid. At least in certain embodiments, the filter apparatus may be controlled by controlling operation of the pump. The need to provide an actuator for one or more of the valve assembly may be reduced or avoided. This may simplify the filter apparatus and the operation of the filter apparatus. For example, the filter apparatus may be configured to operate in a filtration mode when the pump is operating; and in a backwashing mode when the pump is not operating. The operation of the filter apparatus may be automated or partially automated in dependence on operation of the pump. At least in certain embodiments, the filter apparatus may be a pump- controlled filter apparatus.

According to a further aspect of the present invention there is provided a controller for controlling operation of the filter apparatus described herein. The controller may be configured to implement the method(s) described herein. In particular, the controller may control operation of a pump to control operation of the filter apparatus.

Any control unit or controller described herein may suitably comprise a computational device having one or more electronic processors. The system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term "controller" or "control unit" will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller or control unit, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. The control unit or controller may be implemented in software run on one or more processors. One or more other control unit or controller may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which:

Figure 1 shows a schematic representation of a filter system incorporating a filter apparatus in accordance with an embodiment of the present invention;

Figure 2 is a schematic representation of the filter apparatus shown in Figure 1 ;

Figure 3 is a perspective view of a filter element used in the mechanical filter apparatus according to the present invention;

Figure 4 is a schematic representation of the filter apparatus in accordance with a further embodiment of the present invention;

Figure 5 is a schematic representation of the filter apparatus in accordance with a further embodiment of the present invention;

Figure 6 is a schematic representation of the filter apparatus in accordance with a further embodiment of the present invention; and

Figure 7 is a schematic representation of the filter apparatus in accordance with a further embodiment of the present invention.

DETAILED DESCRIPTION A filter system S incorporating a filter apparatus 1 in accordance with an embodiment of the present invention will now be described with reference to the accompanying Figures. As described herein, the filter apparatus 1 is operable in a filtration mode to perform filtration, and in a backwashing (cleaning mode).

The filter system S is configured to filter a liquid, such as water. As shown schematically in Figure 1 , the filter system S according to the present embodiment is configured to filter water W from a swimming pool 2. A pump 3 is provided for pumping unfiltered water W from the swimming pool 2 to the filter apparatus 1. The water W is filtered by the filter apparatus 1 and the filtered water W returned to the swimming pool 2. The pump 3 may be incorporated into the filter apparatus 1 or may be separate from the filter apparatus 1. As described herein, the pump 3 is used to control operation of the filter apparatus 1.

As shown in Figure 2, the filter apparatus 1 comprises a filter housing 4 which defines a filter chamber 5 having a sidewall 6. The filter chamber 5 is a sealed chamber capable of supporting an operating pressure greater than atmospheric pressure. A plurality of filter elements 7 are disposed in the filter chamber 5 and collectively form a mechanical filter. The filter elements 7 have an open-cell structure. By way of example, the filter apparatus 1 may comprise filter elements 7 of the type illustrated in Figure 3. The filter elements 7 are the subject of the Applicant's earlier International patent application PCT/GB2016/000101 , the contents of which are incorporated herein in their entirety by reference.

The filter housing 4 comprises a tubular member 8 having a central longitudinal axis arranged substantially vertically. The tubular member 8 defines the sidewall 6 of the filter chamber 5. The upper and lower ends of the tubular member 8 are sealed by an upper closure member 9 and a lower closure member 10 respectively to close the filter chamber 5. The tubular member 8 has a substantially uniform cross-section along the central longitudinal axis. In the present embodiment, the tubular member 8 is in the form of a cylinder having a circular cross-section (i.e. a right circular cylinder). The filter chamber 5 may have different cross-sections, for example elliptical, rectangular or square.

The filter apparatus 1 comprises a supply conduit 1 1 for supplying unfiltered water from the swimming pool 2 to an inlet 12 formed in the filter chamber 5. The filter apparatus 1 also comprises a return conduit 13 for returning filtered water from an outlet 14 formed in the filter chamber 5 to the swimming pool 2. The inlet 12 in the present embodiment is formed in the upper closure member 9 and the outlet 14 is formed in the sidewall 6 proximal to the bottom of the filter chamber 5. In the present embodiment, there is a down flow of water W through the filter chamber 5 during filtration, as illustrated in Figure 2. The unfiltered water W is introduced through the inlet 12 at the top of the filter chamber 5; and the filtered water W exits through the outlet 14 at the bottom of the filter chamber 5. The filter chamber 5 is sealed and the operating pressure is greater than atmospheric pressure when the pump 3 supplies unfiltered water W to the filter chamber 5.

The filter apparatus 1 also comprises a drain 16 for draining water from the filter chamber 5. The drain 16 is connected to a drain conduit 17 which may, for example, be connected to waste or to a sump for collecting waste water. In the present embodiment, the drain 16 is a dedicated outlet provided at the bottom of the filter chamber 5. A drain valve 18 is provided for selectively opening and closing the drain 16. The drain valve 18 comprises a drain valve member 19 and a drain valve seat 20. The drain valve member 19 is movable relative to the drain valve seat 20 to open and close the drain valve 18. The drain valve 18 is closed when the drain valve member 19 is seated in the drain valve seat 20; and is open when the drain valve member 19 is unseated from the drain valve seat 20.

An upper mesh 21-1 and a lower mesh 21-2 are provided to retain the filter elements 7 in the filter chamber 5. The upper mesh 21-1 extends over the inlet 12; and the lower mesh 21-1 extends over the outlet 14. The filter apparatus 1 comprises means for introducing air into the filter chamber 5 during backwashing or cleaning. In the present embodiment, the air introducing means (denoted generally by the reference numeral 22) is configured to introduce air into the filter chamber 5 to form bubbles which agitate the filter elements 7. The air introducing means 22 comprises an air supply conduit 23 having an air inlet 24 disposed within the filter chamber 5. An air supply valve 25 is provided to control the flow of fluid through the air supply conduit 23. The air supply conduit 23 in the present embodiment extends downwardly from the upper closure member 9 such that the air inlet 24 is disposed in a lower portion of the filter chamber 5. As described herein, the air supply conduit 23 is configured to enable air to be drawn into the filter chamber 5 through the air inlet 24 by the reduced pressure in the filter chamber 5 caused by the water W draining from the filter chamber 5. The air supply conduit 23 has an air intake which in the present embodiment is open to atmosphere. In a variant, the air supply conduit 23 could be omitted. For example, a one-way air inlet valve could be provided to open in dependence on a decrease in the drop within the filter chamber 5. This variant may, for example, enable purging of water and collected debris from the filter chamber 5 to the drain 16.

The vertical offset between the air inlet 24 and the drain 16 establishes a pressure differential which enables air to be drawn into the filter chamber 5 during backwashing. Thus, the air inlet 24 is disposed at a positioned displaced vertically above the bottom of the drain conduit 17. By establishing a pressure differential, air is introduced into the filter chamber 5 when the drain valve 18 is open. The height of the air inlet 24 within the filter chamber 5 may be adjusted to alter this pressure differential, thereby controlling the rate at which air is introduced into the filter chamber 5 during backwashing. In a variant, the air inlet 24 may comprise an adjustable height outlet nozzle. The outlet nozzle may comprise a telescopic conduit; or may be rotatable about a horizontal axis to adjust the height of the air inlet 24. By adjusting the height of the outlet nozzle, the pressure differential may be altered to controllably adjust the rate at which air is drawn into the filter chamber. The air supply valve 25 is configured to allow air to pass through the air supply conduit 23 during backwashing; and to prevent water exiting the filter chamber 5 through the air supply conduit 23 during filtration. The air supply valve 25 may be in the form of a one-way (check) valve. The air supply valve 25 may, for example, comprise a spring-biased closure member or a closure flap (not shown) configured to open to allow air to be drawn into the air supply conduit 23 and to close to prevent water W exiting through the air supply conduit 23. In the present embodiment, the air supply valve 25 comprises an air supply valve member 26 and an air supply valve seat 27. The air supply valve member 26 is movable between an open position and a closed position. The air supply valve member 26 seats in the air supply valve seat 27 to close the air supply valve 25. The air supply valve member 26 comprises a ball which cooperates with the air supply valve seat 27. The air supply valve member 26 seats in the air supply valve seat 27 at least substantially to seal the air supply conduit 23. The air supply valve member 26 unseats from the air supply valve seat 27 to open the air supply conduit 23. Retaining means, such as a cage or a cup, is provided to retain the air supply valve member 26. Biasing means 28 is provided for biasing the air supply valve member 26 towards the seated position such that the air supply valve 25 is closed. The biasing means 28 could, for example, comprise spring biasing means. In the present embodiment, the air supply valve member 26 is positively buoyant and is biased upwardly against the air supply valve seat 27 when level of the water W in the filter chamber 5 is above the air supply valve 25. During filtration, the hydraulic pressure of the water W in the filter chamber 5 biases the air supply valve member 26 against the air supply valve seat 27.

In a modified arrangement, a three-way valve (not shown) may be provided selectively to connect either the filter chamber 5 or the air supply conduit 23 to the return conduit 13. This implementation of a three-way valve may be used in one or more of the embodiments described herein.

The filter apparatus 1 comprises flow control means for controlling flow through the filter chamber 5. The flow control means comprises an inlet valve 30 and an outlet valve 31. The inlet valve 30 is operable to open and close the supply conduit 11 to control the supply of unfiltered water W to the filter chamber 5. The inlet valve 30 comprises an inlet valve member 32 and an inlet valve seat 33. The inlet valve member 32 is movable between an open position and a closed position. The inlet valve member 32 seats in the inlet valve seat 33 to close the supply conduit 1 1. The inlet valve member 32 unseats from the inlet valve seat 33 to open the supply conduit 1 1. In the present embodiment, the inlet valve member 32 comprises a ball which cooperates with the inlet valve seat 33. The outlet valve 31 comprises an outlet valve member 34 and an outlet valve seat 35. The outlet valve member 34 is movable between an open position and a closed position. The outlet valve member 34 seats in the outlet valve seat 35 to close the supply conduit 11. The outlet valve member 34 unseats from the outlet valve seat 35 to open the supply conduit 1 1. In the present embodiment, the outlet valve member 34 comprises a ball which cooperates with the outlet valve seat 35.

The inlet valve 30 and the outlet valve 31 operate as one-way (check) valves. The inlet valve 30 is adapted to enable liquid to be introduced into the filter chamber 5 from the supply conduit 1 1 ; and to inhibit the return of liquid from the filter chamber 5 to the supply conduit 1 1. The outlet valve 31 is adapted to allow liquid to be discharged from the filter chamber 5 into the return conduit 13; and to inhibit the return of liquid from the return conduit 13 into the filter chamber 5. As described herein, the inlet valve 30 and the outlet valve 31 are configured to operate in concert so as to open the inlet 12 and the outlet 14 simultaneously, and to close the inlet 12 and the outlet 14 simultaneously. Biasing means 38 is provided to bias the inlet valve 30 towards a closed position. The biasing means 38 in the present embodiment comprises spring biasing means, for example comprising a spring member, such as a coil spring, for biasing the inlet valve member 32 towards the inlet valve seat 33. The inlet valve 30 is configured to be displaced to an open position under the action of the water W pumped through the supply conduit 1 1. The water W pumped through the supply conduit 1 1 acts on the surface of the inlet valve member 32 and applies a force sufficient to displace the inlet valve member 32 to the open position. The inlet valve member 32 may optionally comprise a flat surface or a concave surface (for example to form a cup) for increasing the force applied by the incident jet of water W. Alternatively, or in addition, a flow controlled actuator may be provided to actuate the inlet valve 30. The flow controlled actuator could, for example, be displaced in dependence on the action of the water W pumped through the supply conduit 11 , thereby displacing the inlet valve member 32 to an open position. The flow controlled actuator may comprise a member disposed in the supply conduit 1 1 and connected to the inlet valve member 32.

The drain valve 18 and the outlet valve 31 are configured selectively to establish fluid communication between the filter chamber 5 and the drain 16 or between the filter chamber 5 and the outlet 14. The drain valve 18 and the outlet valve 31 in the present embodiment are configured to operate as a multi-port valve. In particular, the drain valve 18 and the outlet valve 31 may be considered as operating as a two position 3-way valve. The drain valve seat 20 and the outlet valve seat 35 are disposed opposite each other in a face-to-face arrangement. The drain valve member 19 and the outlet valve member 34 are formed integrally by a valve element 36 which is disposed between the drain valve seat 20 and the outlet valve seat 35. The valve element 36 may have a dual function since it forms both the drain valve member 19 and the outlet valve member 34. The valve element 36 comprises opposing first and second sides which form the drain valve member 19 and the outlet valve member 34 respectively. The valve element 36 is movable selectively to open and close the drain valve 18 and the outlet valve 31. The valve element 36 is disposed in a first position to close the drain valve 18 and to open the outlet valve 31 , as illustrated in Figure 2. Conversely, the valve element 36 is disposed in a second position to open the drain valve 18 and to close the outlet valve 31 . It will be understood that the drain valve member 19 and the outlet valve member 34 may be formed separately from each. The drain valve member 19 and the outlet valve member 34 could, for example, be formed separately and connected by a connector.

In accordance with an aspect of the present invention, the inlet valve member 32 and the drain valve member 19 are coupled to each other. In the present embodiment, the coupling between the inlet valve member 32 and the drain valve member 19 comprises a coupling member 37. The coupling member 37 forms a mechanical coupling between the inlet valve member 32 and the drain valve member 19. The coupling member 37 is arranged such that, in use, the inlet valve member 32 and the drain valve member 19 are actuated together. The coupling member 37 connects the inlet valve member 32 to the valve element 36 which forms the drain valve member 19. In the present embodiment, the coupling member 37 comprises a connecting rod which is movably mounted inside the filter chamber 5. Other forms of coupling may be provided to couple the inlet valve member 32 and the outlet valve member 34.

The coupling member 37 is configured such that the inlet valve 30 is closed when the drain valve 18 is open; and, conversely, the inlet valve 30 is open when the drain valve 18 is closed (as illustrated in Figure 2). The coupling member 37 couples the inlet valve member 32 to the valve element 36 which forms both the drain valve member 19 and the outlet valve member 34. The biasing means 38 applies a biasing force to the valve element 36, thereby controlling both the drain valve member 19 and the outlet valve member 34. As described herein, the valve element 36 is disposed in a first position to close the drain valve 18 and to open the outlet valve 31 ; and in a second position to open the drain valve 18 and to close the outlet valve 31. The biasing means 38 is configured to apply a biasing force which biases the valve element 36 towards the second position. The drain valve member 19 is biased away from the drain valve seat 20 so as to open the drain valve 18; and the outlet valve member 34 is biased towards the outlet valve seat 35 so as to close the outlet valve 31.

The filter apparatus 1 is controlled in dependence on the supply of water W to the filter chamber 5. The drain valve 18, the inlet valve 30, and the outlet valve 31 are each controlled (directly or indirectly) in dependence on the hydraulic pressure of the water W in the filter apparatus 1. As described herein, the inlet valve 30 is opened when the force applied by the water W pumped through the supply conduit 11 is sufficient to overcome the biasing force applied by the biasing means 38. The coupling member 37 connects the inlet valve member 32 to the valve element 36. Thus, displacement of the inlet valve 30 results in a corresponding displacement of the valve element 36. As described herein, opening of the inlet valve 30 closes the drain valve 18 and opens the outlet valve 31. When the supply of water W is stopped, the biasing means 38 returns the inlet valve member 32 and the outlet valve member 34 to their respective seated positions, thereby sealing the filter chamber 5. The displacement of the valve element 36 by the biasing means 38 unseats the drain valve member 19 and opens the drain valve 18.

It will be understood, therefore, that the filter apparatus 1 in accordance with the present embodiment is controlled in dependence on the operation of the pump 3. The supply of water W to the filter apparatus 1 is controlled by operation of the pump 3. Thus, controlling operation of the pump 3 enables the filter apparatus 1 to be controlled. The filter apparatus 1 is configured to perform filtration when the pump 3 is activated and water W is pumped to the filter chamber 5; and to perform backwashing when the pump 3 is deactivated and water W is not being pumped into the filter chamber 5. The pump 3 is provided in the supply conduit 11 to pump water W into the filter chamber 5 through the inlet 12. In a variant, the pump 3 could be provided in the return conduit 13 to draw water out of the filter chamber 5 through the outlet 14. The filter apparatus 1 comprises an electronic control unit (ECU) 39 for controlling operation of the pump 3. The ECU 39 comprises a processor 40 and a memory 41. The ECU 39 is configured to control activation and deactivation of the pump 3, for example in dependence on a timer schedule. The timer schedule may, for example, define a daily, weekly, monthly or annual filtration and backwashing schedule. It will be understood that the timer schedule may be defined in dependence on operating conditions, such as the expected filtration load. The operation of the filter apparatus 1 in accordance with the embodiment shown in Figure 2 will now be described.

The ECU 39 activates the pump 3 to pump water W to the filter apparatus 1 from the swimming pool 2. The water W is supplied to the filter apparatus 1 through the supply conduit 1 1. The hydraulic pressure of the water W in the supply conduit 11 acts on the surface of the inlet valve member 32. When the acting force is sufficient to overcome the force applied by the biasing means 38, the inlet valve member 32 is unseated from the inlet valve seat 33 and the inlet valve 30 is opened. The water W is pumped into the filter chamber 5 by the pump 3 through the inlet 12. The inlet valve member 32 is coupled to the valve element 36 by the coupling member 37. The valve element 36 forms both the drain valve member 19 and the outlet valve member 34 such that the displacement of the inlet valve member 32 actuates both the drain valve 18 and the outlet valve 31. The unseating of the inlet valve member 32 also unseats the outlet valve member 34 from the outlet valve seat 35, thereby opening the outlet valve 31. Simultaneously, the drain valve member 19 is seated in the drain valve seat 20, thereby closing the drain 16. Thus, in dependence on the activation of the pump 3 to pump water W to the filter apparatus 1 , the inlet valve 30 and the outlet valve 31 are opened, and the drain valve 18 is closed. This configuration is suitable for performing filtration of the water W in the filter chamber 5. Thus, the filter apparatus 1 is automatically configured to operate in the filtration mode in dependence on activation of the pump 3.

When operating in the filtration mode, the water W is pumped into the filter chamber 5 through the inlet 12 and exits through the outlet 14. A plurality of filter elements 7 are disposed in the filter chamber 5. When the water W is introduced into the filter chamber 5, the filter elements 7 form a filter pack 29. In the present embodiment, the filter elements 7 have substantially neutral buoyancy and, due to the downwards flow of the water W through the filter chamber 5, the filter pack 29 forms at the bottom of the filter chamber 5, as illustrated in Figure 2. The filter elements 7 disposed in the filter chamber 5 may have a negative buoyancy or a positive buoyancy in water. The flow of water W through the filter chamber 5 compacts the filter elements 7 together, thereby forming the filter pack 29. The movement of the filter elements 7 within the filter pack 29 is restricted. The resulting filter pack 29 is substantially static and is suitable for performing mechanical filtration of the water W.

The ECU 39 selectively de-activates the pump 3 in accordance with the predefined timer schedule. The pump 3 is deactivated and the water W is no longer pumped to the filter apparatus 1. The hydraulic pressure of the water W in the supply conduit 11 is thereby reduced and the acting force on the inlet valve member 32 is insufficient pressure to overcome the biasing force applied by the biasing means 38. The biasing means 38 biases the inlet valve member 32 towards the inlet valve seat 33 and the inlet valve 30 is closed. By virtue of the coupling member 37, the biasing means 38 also displaces the valve element 36. The seating of the inlet valve member 32 also seats the outlet valve member 34 in the outlet valve seat 35, thereby closing the outlet valve 31. Simultaneously, the drain valve member 19 is unseated from the drain valve seat 20, thereby opening the drain 16. Thus, in dependence on the deactivation of the pump 3, the inlet valve 30 and the outlet valve 31 are closed, and the drain valve 18 is opened. This configuration is suitable for performing backwashing of the filter apparatus 1. Thus, the filter apparatus 1 is automatically configured to operate in backwashing mode in dependence on de-activation of the pump 3.

When operating in the backwashing mode, the filter apparatus 1 is configured to discharge the water W from the filter chamber 5 through the drain 16. The inlet valve 30 and the outlet valve 31 are closed such that the filter chamber 5 is at least substantially sealed. The discharge of water W through the drain 16 thereby reduces the operating pressure in the filter chamber 5. The reduced pressure in the filter chamber 5 unseats the air supply valve member 26 from the air supply valve seat 27 and opens the air supply valve 25. The air inlet 24 is thereby opened and air is drawn into the filter chamber 5 as the water W is discharged. The air introduced through the air inlet 24 forms bubbles in the water W in the filter chamber 5. The bubbles interact with the filter elements 7 to dislodge trapped debris and help perform cleaning of the filter chamber 5. The cleaning cycle continues until the water W is drained from the filter chamber 5.

During backwashing, the pump 5 is stopped to inhibit the supply of water from the swimming pool 2 to the filter housing 6. As described herein, the inlet valve 30 and the outlet valve 31 are closed by the biasing means 38. The drainage valve 18 is opened to allow the water in the filter housing 6 to flow through the drain 16 into the drain conduit 17. Since the filter housing 6 is sealed, the flow of water out of the filter chamber 5 reduces the pressure within the filter housing 6 causing the one-way valve 24 to open allowing air to be drawn into the air supply conduit 23. By draining water from the sealed filter chamber 5, the operating pressure drops below atmospheric pressure, thereby drawing air into the filter chamber 5 through the air supply conduit 23. The air is then introduced into the filter chamber 5 through the air inlet apertures 25. The resulting air bubbles travel upwardly through the water in the filter chamber 5 and disrupt the suspended filter elements 7. The filter elements 7 are agitated by the air bubbles and the filter pack 29 is broken up. It will be appreciated that the water in the filter chamber 5 continues to drain through the drain 16, such that the level of the water continues to drop causing further agitation of the filter elements 7 within the filter chamber 5. It will be understood that, by agitating the filter elements 7, material and debris filtered by the filter elements 7 is dislodged and returned to the water within the filter chamber 5. The agitation of the filter elements 7 continues until the water level in the filter chamber 5 drops below the position of the air inlet 25. The introduction of air into the filter chamber 5 continues concurrently with drainage of the water from the filter chamber 5. By draining the water through the drain 16, the material and debris is expelled from the filter chamber 5. The filter elements 7 may thereby be cleaned ready to perform additional filtration. The pressure in the filter chamber 5 returns to atmospheric pressure. The ECU 39 may be configured to de-activate the pump 3 for a predetermined time period to enable the water W to drain from the filter chamber 5. The ECU 39 then re-activates the pump 3 to pump water W to the filter apparatus 1. It will be understood that the supply of water W to the filter chamber 5 causes the inlet valve 30 to re-open, thereby allowing the filter chamber 5 to be re-filled. The ECU 39 may be configured to repeatedly deactivate the pump 3 to perform additional cleaning, for example the filter chamber 5 may be drained and refilled more than once during a backwashing mode.

A filter apparatus 1 in accordance with a further embodiment of the present invention will now be described with reference to Figure 4. The description of the filter apparatus 1 in accordance with the present embodiment focuses on the differences over the embodiment described herein with reference to Figure 2. Like reference numerals are used for like components.

The filter apparatus 1 is configured to filter water W from a swimming pool 2. A pump 3 is provided to pump unfiltered water W from the swimming pool 2 to the filter apparatus 1. As shown in Figure 4, the filter apparatus 1 comprises a filter housing 4 which defines a filter chamber 5 having a sidewall 6. The filter chamber 5 is a sealed chamber capable of supporting an operating pressure greater than atmospheric pressure. A plurality of filter elements 7 are disposed in the filter chamber 5.

The filter housing 4 comprises a tubular member 8 defining the sidewall 6 of the filter chamber 5. The upper and lower ends of the tubular member 8 are sealed by an upper closure member 9 and a lower closure member 10 respectively to close the filter chamber 5. The filter apparatus 1 comprises a supply conduit 11 for supplying unfiltered water from the swimming pool 2 to an inlet 12 formed in the filter chamber 5. The filter apparatus 1 also comprises a return conduit 13 for returning filtered water from an outlet 14 formed in the filter chamber 5 to the swimming pool 2. The inlet 12 in the present embodiment is formed in the lower closure member 10 and the outlet 14 is formed in upper closure member 9. In the present embodiment, there is an up flow of water W through the filter chamber 5 during filtration, as illustrated in Figure 4. The unfiltered water W is introduced through the inlet 12 at the bottom of the filter chamber 5; and the filtered water W exits through the outlet 14 at the top of the filter chamber 5. The filter chamber 5 is sealed and the operating pressure is greater than atmospheric pressure when the pump 3 supplies unfiltered water W to the filter chamber 5. The filter apparatus 1 also comprises a drain 16 for draining water from the filter chamber 5. The drain 16 is connected to a drain conduit 17 which is connected to waste or to a sump. In the present embodiment, the drain conduit 17 extends through the sidewall 6 of the filter chamber 5. A drain valve 18 is provided for selectively opening and closing the drain 16. The drain valve 18 comprises a drain valve member 19 and a drain valve seat 20. The drain valve member 19 is movable relative to the drain valve seat 20 to open and close the drain valve 18. The drain valve 18 is closed when the drain valve member 19 is seated in the drain valve seat 20; and is open when the drain valve member 19 is unseated from the drain valve seat 20. A guard (not shown) is provided around the drain valve member 19 to prevent the filter elements 7 escaping from the filter chamber 5 when the drain valve 18 is open.

The filter apparatus 1 comprises air introducing means (denoted generally by the reference numeral 22) for introducing air into the filter chamber 5 to form bubbles which agitate the filter elements 7. The air introducing means 22 comprises an air supply conduit 23 having an air inlet 24 disposed within the filter chamber 5. An air supply valve 25 is provided to control the flow of fluid through the air supply conduit 23. The air supply conduit 23 has an air intake which in the present embodiment is open to atmosphere. The air supply valve 25 is configured to all through the air supply conduit 23 during backwashing; and to prevent water exiting the filter chamber 5 through the air supply conduit 23 during filtration. The air supply valve 25 may be in the form of a one-way (check) valve. The air supply valve 25 may, for example, comprise a spring-biased closure member configured to open to allow air to be drawn into the air supply conduit 23 and to close to prevent water W exiting through the air supply conduit 23.

The filter apparatus 1 comprises an inlet valve 30 and an outlet valve 31. The inlet valve 30 is operable to open and close the supply conduit 11 to control the supply of unfiltered water W to the filter chamber 5. The inlet valve 30 and the outlet valve 31 operate as one-way (check) valves. The inlet valve 30 is adapted to enable liquid to be introduced into the filter chamber 5 from the supply conduit 11 ; and to inhibit the return of liquid from the filter chamber 5 to the supply conduit 1 1. The outlet valve 31 is adapted to allow liquid to be discharged from the filter chamber 5 into the return conduit 13; and to inhibit the return of liquid from the return conduit 13 into the filter chamber 5.

The inlet valve 30 comprises an inlet valve member 32 and an inlet valve seat 33. The inlet valve member 32 is movable between an open position and a closed position. The inlet valve member 32 seats in the inlet valve seat 33 to close the supply conduit 1 1. The inlet valve member 32 unseats from the inlet valve seat 33 to open the supply conduit 1 1. The inlet valve 30 comprises inlet valve biasing means 38 to bias the inlet valve 30 towards a closed position. The inlet valve biasing means 38 in the present embodiment comprises the mass of the inlet valve member 32 which biases the inlet valve member 32 towards the inlet valve seat 33 under the action of gravity. The outlet valve 31 comprises an outlet valve member 34 and an outlet valve seat 35. The outlet valve member 34 is movable between an open position and a closed position. The outlet valve member 34 seats in the outlet valve seat 35 to close the supply conduit 11. The outlet valve member 34 unseats from the outlet valve seat 35 to open the supply conduit 1 1. The outlet valve 31 comprises an outlet valve biasing means 43 for biasing the outlet valve member 34 towards the seated position. The outlet valve biasing means 43 may, for example, comprise a spring element, such as a coil spring. The inlet valve 30 and the outlet valve 31 are configured to operate in concert so as to open the inlet 12 and the outlet 14 simultaneously, and to close the inlet 12 and the outlet 14 simultaneously. The inlet valve 30 is configured to be displaced to an open position under the action of the water W pumped through the supply conduit 1 1. The water W pumped through the supply conduit 1 1 acts on the surface of the inlet valve member 32 and applies a force sufficient to displace the inlet valve member 32 to the open position. The inlet valve member 32 may optionally comprise a flat surface or a concave surface (for example to form a cup) for increasing the force applied by the incident jet of water W. The hydraulic pressure of the water W in the filter chamber 5 applies a force to the outlet valve member 34. When the force is sufficient to overcome the biasing force applied by the outlet valve biasing means 43, the outlet valve member 34 is unseated from the outlet valve seat 35 and the outlet valve 31 is opened.

The drain valve 18 and the inlet valve 30 are configured selectively to establish fluid communication between the filter chamber 5 and the drain 16 or between the filter chamber 5 and the inlet 12. The drain valve 18 and the inlet valve 30 in the present embodiment are configured to operate as a multi-port valve. In particular, the drain valve 18 and the inlet valve 30 operate as a two position 3-way valve. The drain valve seat 20 and the inlet valve seat 33 are disposed opposite each other in a face-to-face arrangement. The drain valve member 19 and the inlet valve member 32 are formed integrally by a valve element 36 which is disposed between the drain valve seat 20 and the inlet valve seat 33. The valve element 36 forms both the drain valve member 19 and the inlet valve member 32 in this embodiment. The valve element 36 comprises opposing first and second sides which form the drain valve member 19 and the inlet valve member 32 respectively. The valve element 36 is movable selectively to open and close the drain valve 18 and the inlet valve 30. The valve element 36 is disposed in a first position to close the drain valve 18 and to open the inlet valve 30, as illustrated in Figure 4. Conversely, the valve element 36 is disposed in a second position to open the drain valve 18 and to close the inlet valve 30. In the present embodiment, the valve element 36 translates between said first and second positions. It will be understood that the drain valve member 19 and the inlet valve member 32 may be formed separately from each. The drain valve member 19 and the outlet valve member 34 could, for example, be formed separately and connected by a connector.

In accordance with an aspect of the present invention, the inlet valve member 32 and the drain valve member 19 are coupled to each other. In the present embodiment, the coupling is established by forming the inlet valve member 32 and the drain valve member 19 on opposing faces of the valve element 36. Other forms of coupling may be provided to couple the inlet valve member 32 and the outlet valve member 34. The valve element 36 is configured such that the inlet valve 30 is closed when the drain valve 18 is open; and, conversely, the inlet valve 30 is open when the drain valve 18 is closed (as illustrated in Figure 4). The biasing means 38 applies a biasing force to the valve element 36, thereby controlling both the drain valve member 19 and the outlet valve member 34. As described herein, the valve element 36 is disposed in a first position to close the drain valve 18 and to open the outlet valve 31 ; and in a second position to open the drain valve 18 and to close the outlet valve 31. The biasing means 38 is configured to apply a biasing force which biases the valve element 36 towards the second position. The drain valve member 19 is biased away from the drain valve seat 20 so as to open the drain valve 18; and the inlet valve member 32 is biased towards the inlet valve seat 33 so as to close the inlet valve 30. As in the previous embodiment, the filter apparatus 1 is controlled in dependence on the supply of water W to the filter chamber 5. The drain valve 18, the inlet valve 30, and the outlet valve 31 are each controlled (directly or indirectly) in dependence on the hydraulic pressure of the water W in the filter apparatus 1. As described herein, the inlet valve 30 is opened when the force applied to the inlet valve member 32 is sufficient to overcome the biasing force applied by the inlet valve biasing means 38. The displacement of the inlet valve 30 results in a corresponding displacement of the drain valve member 19 which closes the drain valve 18. The supply of water W into the filter chamber 5 increases the pressure differential across the outlet valve member 34 and the resulting force unseats the outlet valve member 34 from the outlet valve seat 35, thereby opening the outlet valve 31. When the supply of water W is stopped, the inlet valve biasing means 38 and the outlet valve biasing means 43 return the inlet valve member 32 and the outlet valve member 34 to their respective seated positions, thereby sealing the filter chamber 5. The displacement of the valve element 36 by the inlet valve biasing means 38 unseats the drain valve member 19 and opens the drain valve 18. The water W in the filter chamber 5 is discharged through the drain 16 thereby reduces the operating pressure in the filter chamber 5. The reduced pressure in the filter chamber 5 unseats the air supply valve member 26 from the air supply valve seat 27 and opens the air supply valve 25. The air inlet 24 is thereby opened and air is drawn into the filter chamber 5 as the water W is discharged. It will be understood, therefore, that the filter apparatus 1 in accordance with the present embodiment is controlled in dependence on the supply of water W. The supply of water W to the filter apparatus 1 is controlled by operation of the pump 3. Thus, controlling operation of the pump 3 enables the filter apparatus 1 to be controlled. The filter apparatus 1 is configured to perform filtration when the pump 3 is activated and water W is pumped to the filter chamber 5; and to perform backwashing when the pump 3 is deactivated and water W is not being pumped into the filter chamber 5. The pump 3 is provided in the supply conduit 11 to pump water W into the filter chamber 5 through the inlet 12. In a variant, the pump 3 could be provided in the return conduit 13 to draw water out of the filter chamber 5 through the outlet 14.

The filter apparatus 1 comprises an electronic control unit (ECU) 39 for controlling operation of the pump 3. The ECU 39 comprises a processor 40 and a memory 41. The ECU 39 is configured to control activation and deactivation of the pump 3, for example in dependence on a timer schedule. The ECU 39 activates the pump 3 to pump water W to the filter apparatus 1 from the swimming pool 2. The water W is supplied to the filter apparatus 1 through the supply conduit 11. The hydraulic pressure of the water W in the supply conduit 11 applies a force to the inlet valve member 32. When the acting force is sufficient to overcome the force applied by the inlet valve biasing means 38, the inlet valve member 32 is unseated from the inlet valve seat 33 and the inlet valve 30 is opened. The continued flow of water W through the inlet 12 maintains the inlet valve 30 in the open position. The valve element 36 forms both the drain valve member 19 and the inlet valve member 32 such that the displacement of the inlet valve member 32 also actuates the drain valve 18 to close the drain 16. The water W is pumped into the filter chamber 5 by the pump 3 through the inlet 12. The resulting increase in the hydraulic pressure in the filter chamber 5 unseats the outlet valve member 34 from the outlet valve seat 35, thereby opening the outlet valve 31. It will be understood that, in dependence on the activation of the pump 3 to pump water W to the filter apparatus 1 , the inlet valve 30 is opened, the outlet valve 31 is opened, and the drain valve 18 is closed. This configuration is suitable for performing filtration of the water W in the filter chamber 5. The ECU 39 selectively de-activates the pump 3 in accordance with the predefined timer schedule. The pump 3 is deactivated and the water W is no longer pumped to the filter apparatus 1. The force applied to the inlet valve member 32 is thereby reduced (or removed) and the biasing means 38 biases the inlet valve member 32 towards the inlet valve seat 33 and the inlet valve 30 is closed. The biasing means 38 displaces the valve element 36 such that the drain valve member 19 is unseated from the drain valve seat 20, thereby opening the drain 16. The outlet valve member 34 seated in the outlet valve seat 35, thereby closing the outlet valve 31. Thus, in dependence on the de-activation of the pump 3, the inlet valve 30 and the outlet valve 31 are closed, and the drain valve 18 is opened. This configuration is suitable for performing backwashing of the filter apparatus 1. Thus, the filter apparatus 1 is automatically configured to operate in the backwashing mode in dependence on de-activation of the pump 3.

A variant of the filter apparatus 1 described herein with reference to Figure 4 is illustrated in Figure 5. Like reference numerals are again used for like components.

The filter apparatus 1 in accordance with the present embodiment comprises a modified air introducing means 22 for introducing air into the filter chamber 5. The air introducing means 22 comprises an air supply conduit 23 having an air inlet 24 disposed within the filter chamber 5. An air supply valve 25 is provided to control the flow of fluid through the air supply conduit 23. The air supply conduit 23 has an air intake which in the present embodiment is open to atmosphere.

The air supply valve 25 is configured to allow air to pass through the air supply conduit 23 during backwashing; and to prevent water exiting the filter chamber 5 through the air supply conduit 23 during filtration. The air supply valve 25 may be in the form of a one-way (check) valve. The air supply valve 25 may, for example, comprise a spring-biased closure member configured to open to allow air to be drawn into the air supply conduit 23 and to close to prevent water W exiting through the air supply conduit 23.

The air supply valve 25 comprises an air supply valve member 26 and an air supply valve seat 27. The air supply valve member 26 is movable between an open position and a closed position. The air supply valve member 26 comprises a conical or part-conical valve member which seats in the air supply valve seat 27 to close the air supply valve 25. The air supply valve member 26 seats in the air supply valve seat 27 at least substantially to seal the air supply conduit 23. The air supply valve member 26 in the present embodiment is connected to the valve element 36 which forms the inlet valve member 32 and the drain valve member 19. Thus, the air supply valve member 26 in the present embodiment is configured to operate in conjunction with the inlet valve 30 and the drain valve 18.

The operation of the filter apparatus 1 in accordance with the present embodiment is substantially unchanged from the previous embodiment. In use, the pump 3 is operated to control the supply of water W to the filter chamber 5. The supply of water W to the filter chamber 5 selectively opens and closes the inlet valve 30 and the outlet valve 31. During filtration, the pump 3 is energized to pump water W to the filter chamber 5. The supply of water W displaces the valve element 36 to open the inlet valve 30 to introduce water W into the filter chamber 5. The increased hydraulic pressure in the filter chamber 5 opens the outlet valve 31 and the water W is pumped through the filter chamber 5 and filtered by the filter elements 7. The increased pressure in the filter chamber 5 closes the air supply valve 25 to inhibit water being expelled from the filter chamber 5 through the air supply conduit 23. To perform backwashing, the pump 3 is de-energised and the inlet valve member 32 closes the inlet valve 30 and opens the drain valve 18. The water W in filter chamber 5 is drained to waste. Since the inlet valve 30 and the outlet valve 31 are both closed, the filter chamber is at least substantially sealed. The resulting reduction in the pressure in the filter chamber 5 opens the air supply valve 25 and air is introduced into the filter chamber 5 to agitate the filter elements 7. The filtration mode is restarted by re-energising the pump 3. Thus, the filtration and backwashing functions of the filter apparatus 1 can be controlled directly from the operation of the pump 3.

A filter apparatus 1 in accordance with a further embodiment of the present invention will now be described with reference to Figure 6. The description of the filter apparatus 1 in accordance with the present embodiment focuses on the differences over the embodiment described herein with reference to Figure 2. Like reference numerals are used for like components.

The present embodiment comprises a modified drain valve 18 and a modified inlet valve 30. In particular, a hydraulically operated multi-port valve 45 is provided for controlling the low of water W to and from the filter chamber 5. The multi-port valve 45 comprises a hydraulic actuator 46 having a hydraulic control line 47 connected to the supply conduit 1 1. The hydraulic actuator 46 in the present embodiment comprises a single action piston 48. The hydraulic actuator 46 also comprises biasing means 38 in the form of a return spring 49. The single action piston 48 is controlled in dependence on the hydraulic pressure of the water W in the supply conduit 1 1. The drain valve member 19 and the inlet valve member 32 are coupled to the single action piston 48 to form a valve element 36. The hydraulic actuator 46 is configured such that the return spring 49 biases the single action piston 48 to a first position in which the drain valve member 19 is open and the inlet valve member 32 is closed. The single action piston 48 is actuated in dependence on the hydraulic pressure in the supply conduit 11 to a second position in which the drain valve member 19 is closed and the inlet valve member 32 is open. The hydraulic pressure of the water W in the supply conduit 11 is dependent on the operation of the pump 3. The hydraulic pressure in the supply conduit 1 1 when the pump 3 is activated to pump water to the filter apparatus 1. It will be understood that the operation of the hydraulic actuator 46 is controlled by operation of the pump 3.

In use, the return spring 49 biases the single action piston 48 to the first position in which the drain valve member 19 is open and the inlet valve member 32 is closed. The water in the filter chamber 5 will therefore discharge through the drain 6. When the pump 3 is activated, the hydraulic pressure in the supply conduit 1 1 and the hydraulic control line 47 increases and is sufficient to overcome the biasing force applied by the return spring 49, thereby actuating the single action piston 48 is actuated. The single action piston 48 is displaced to the second position in which the drain valve member 19 is closed and the inlet valve member 32 is open. The water W is pumped into the filter chamber 5 through the open inlet valve member 32. The operation of the outlet valve 31 is unchanged from the earlier embodiment. The supply of water W to the filter chamber 5 thereby opens the outlet valve 31 to allow the return of filtered water W to the swimming pool 2. When the pump 3 is deactivated, the resulting decrease in the hydraulic pressure in the supply conduit 1 1 and the hydraulic control line 47 causes the single action piston 48 to return to the first position in which the drain valve 18 is open and the inlet valve 30 is closed. The outlet valve 31 is closed due to the resulting decrease in the force acting on the outlet valve member 34 as the pressure differential decreases. The water W in the filter chamber 5 is discharged through the drain 16 and the reduced pressure in the filter chamber 5 causes the air supply valve 25 to open and air to be introduced through the air inlet 24, thereby agitating the filter elements 7. The filter apparatus 1 in accordance with the present embodiment is operated in the filtration mode and the backwashing mode in controlled by operation of the pump 3. In accordance with the other embodiments described herein, the pump 3 may be controlled by an ECU 39, for example on a predetermined timer schedule. A filter apparatus 1 in accordance with a further embodiment of the present invention will now be described with reference to Figure 7. The description of the filter apparatus 1 in accordance with the present embodiment focuses on the differences over the embodiment described herein with reference to Figure 2. Like reference numerals are used for like components. The drain valve 18 and the inlet valve 30 are configured selectively to establish fluid communication between the filter chamber 5 and the drain 16 or between the filter chamber 5 and the inlet 12. The drain valve 18 and the inlet valve 30 in the present embodiment are configured to operate as a multi-port valve. In particular, the drain valve 18 and the inlet valve 30 operate as a two position 3-way valve. The drain valve seat 20 and the inlet valve seat 33 are disposed opposite each other in a face-to-face arrangement. The drain valve member 19 and the inlet valve member 32 are formed integrally by a valve element 36 which is disposed between the drain valve seat 20 and the inlet valve seat 33. The valve element 36 in the present embodiment comprises a pivoting flap. The valve element 36 forms both the drain valve member 19 and the inlet valve member 32. The valve element 36 in the present embodiment comprises a pivoting flap having opposing first and second sides which form the drain valve member 19 and the inlet valve member 32 respectively. The valve element 36 is movable selectively to open and close the drain valve 18 and the inlet valve 30. The valve element 36 is disposed in a first position to close the drain valve 18 and to open the inlet valve 30, as illustrated in Figure 4. Conversely, the valve element 36 is disposed in a second position to open the drain valve 18 and to close the inlet valve 30. In the present embodiment, the valve element 36 is pivotably mounted and pivots between said first and second positions. Biasing means 38 is provided to bias the valve element 36 towards the second position in which the inlet valve 30 is closed. The biasing means 38 may, for example, comprise a spring element, such as a coil spring or a leaf spring. The biasing means 38 applies a biasing force to the valve element 36, thereby controlling both the drain valve member 19 and the outlet valve member 34. The drain valve member 19 is biased away from the drain valve seat 20 so as to open the drain valve 18; and the inlet valve member 32 is biased towards the inlet valve seat 33 so as to close the inlet valve 30.

In use, the biasing means 38 biases the valve element 36 to the second position in which the drain valve member 19 is open and the inlet valve member 32 is closed. The water in the filter chamber 5 will therefore discharge through the drain 6. When the pump 3 is activated, the water W pumped through the supply conduit 1 1 by the pump 3 applies a force to the second side of the valve element 36 which forms the inlet valve member 32. The force acting on the valve element 35 when the pump 3 is operating is sufficient to overcome the biasing force applied by the biasing means 38, thereby displacing the valve element 36 to the first position in which the drain valve member 19 is closed and the inlet valve member 32 is open. The water W is pumped into the filter chamber 5 through the open inlet valve member 32 and maintains the inlet valve member 34 in the open position. The operation of the outlet valve 31 is unchanged from the earlier embodiment. The supply of water W to the filter chamber 5 thereby opens the outlet valve 31 to allow the return of filtered water W to the swimming pool 2. When the pump 3 is deactivated, the resulting decrease in the force applied to the inlet valve member 34 is no longer sufficient to overcome the biasing force applied by the biasing means 38. The valve element 36 is pivoted by the biasing means 38 towards the first position in which the drain valve 18 is open and the inlet valve 30 is closed. The water W in the filter chamber 5 is discharged through the drain 16 and the reduced pressure in the filter chamber 5 causes the air supply valve 25 to open and air to be introduced through the air inlet 24, thereby agitating the filter elements 7.

The filter apparatus 1 described herein has is suitable for use where the flow rate of the liquid through the filter chamber 5 is relatively high. Although not essential, a relatively high flow rate may improve operation of the inlet valve 30 in dependence on the supply of water W through the supply conduit 1 1. In order to allow operation at a high flow rate, the filter elements may each have an open cell structure. Each filter element may comprise one or more open cells. The filter elements may form a static filter pack in the filter chamber to mechanically filter the liquid. It has been recognised that the open cell structure of the filter elements 7 enables effective filtration to be performed at higher flow speeds (i.e. flow rate per unit cross-sectional area) than known filters, such as sand bed filters. By increasing the flow rate per unit cross- sectional area of the filter pack 29, the cross-sectional area of the filter apparatus 1 may be reduced while maintaining the flow rate through the filter pack 29. Thus, at least in certain embodiments, the size of the filter apparatus may be reduced compared to prior art systems.

The flow rate per unit cross-sectional area of the static filter pack 29 may be expressed in units of m ³ /m ² /h (i.e. the volume of liquid (m ³ ) for a given cross-sectional area of the filter (m ² ) per hour (h)). The flow rate per unit cross-sectional area of the filter pack corresponds to the volumetric flow rate through the static filter pack. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack is greater than 10m ³ /m ² /h, 20m ³ /m ² /h, 30m ³ /m ² /h, 40m ³ /m ² /h, 50m ³ /m ² /h 60m ³ /m ² /h, 65m ³ /m ² /h, 70m ³ /m ² /h or 100m ³ /m ² /h. The filter apparatus 1 may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 550m ³ /m ² /h exclusive. The filter apparatus may be configured such that during filtration a flow rate per unit cross-sectional area of the static filter pack in the range 60m ³ /m ² /h to 150m ³ /m ² /h exclusive. At least in certain embodiments, the filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack in the range 150m ³ /m ² /h to 550m ³ /m ² /h; or 200m ³ /m ² /h to 500m ³ /m ² /h; or 250m ³ /m ² /h to 450m ³ /m ² /h; or 300m ³ /m ² /h to 400m ³ /m ² /h; or 325m ³ /m ² /h to 375m ³ /m ² /h. The filter apparatus may be configured during filtration to provide a flow rate per unit cross-sectional area of the static filter pack of approximately 350m ³ /m ² /h. It will be appreciated that various modifications may be made to the embodiment(s) described herein without departing from the scope of the appended claims.

The filter apparatus has been described herein with particular reference to filtering water in a swimming pool. It will be understood that the filter apparatus may be used for filtering water in other applications, for examples to perform filtration of water in an aquatics system. Furthermore, the filter apparatus may be used to perform filtration of liquids other than water.

The present disclosure relates to a filter apparatus 1 for filtering a liquid (W). The filter apparatus 1 includes a filter chamber 5 having an inlet and an outlet; and a drain for draining liquid from the filter chamber 5. An inlet valve assembly is provided for selectively opening and closing the inlet. The inlet valve assembly has an inlet valve member 32 movable between a closed position and an open position. A drain valve assembly is provided for selectively opening and closing the drain. The drain valve assembly comprising a drain valve member 18 movable between a closed position and an open position. The inlet valve member 32 is coupled to the drain valve member 18. The inlet valve assembly may be operable in dependence on a hydraulic pressure of the liquid supplied to the filter apparatus 1.