Abstract:
The present invention provides a water filtration and sterilisation device comprising a container having an inlet conduit and an outlet conduit, a closure valve at said inlet conduit, a filter means upstream of said inlet conduit, a flow prevention means in said outlet conduit and an ultra violet radiation source within said container. The valve is adapted to be opened for a first time period to admit water into the container via the filter means. The ultra violet radiation source is operable for a second time period to sterilise water in said chamber. The first time period is shorter than said second time period. The flow prevention means is operable to deliver sterilised water on demand from the container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. national stage application of International Application No. PCT/IB2007/003458 filed Nov. 13, 2007, which designates the United States of America, and claims priority to Great Britain application number 0622705.2 filed Nov. 14, 2006. The contents of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates to a water filtration and sterilisation device and particularly to a domestic water filtration and sterilisation device. 
       BACKGROUND 
       [0003]    A domestic water filtration jug typically comprises a jug body into the upper region of which there is nested an inlet container having a removable filtration element. Water, for example tap water, can be introduced into the container whereupon it is fed by gravity through the filtration element to the lower region of the jug body. The filtration element may contain an appropriate filtration means such as, for example, an activated carbon bed or an ion exchange matrix. The filtered water can be retained in the lower region of the jug body until it is poured therefrom by tipping the jug body. 
         [0004]    The nesting of the inlet container within the jug body means that the jug body can only ever be partially filled as around half of the jug body is taken up by the inlet container. A user may typically keep the filtration jug in their refrigerator. It will thus be appreciated that a conventional filtration jug thus wastes space within the refrigerator. The filtration element typically only removes particles, chemicals and heavy metals as water passes from the inlet container to the lower region of the jug body. The filtration element thus does not remove biological contaminants such as, for example, bacteria. A further drawback is that the filtered water may be kept in the lower region of the jug body for a prolonged period of time during which it may lose its freshness, for example by coming into contact with airborne contaminants. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the present invention there is provided a water filtration and sterilisation device comprising a container having an inlet conduit and an outlet conduit, a closure valve at said inlet conduit, a filter means upstream of said inlet conduit, a flow prevention means in said outlet conduit and an ultra violet radiation source within said container, whereby the valve is adapted to be opened for a first time period to admit water into the container via the filter means, the ultra violet radiation source is operable for a second time period to sterilise water in said chamber, and said flow prevention means is operable to deliver sterilised water on demand from the container, wherein said first time period is shorter than said second time period. 
         [0006]    The present invention thus provides a device which is operable to both filter and sterilise water prior to it being dispensed to a user. 
         [0007]    The flow prevention means may comprise a valve which is operable by a user of the device to selectively permit or block the flow of water through the outlet conduit. The valve may be manually operable and, for example, may take the form of a simple tap fitting. In an alternative embodiment, the valve may be electrically operable. The flow prevention means may alternatively take the form of a pump which, when not in operation, prevents the flow of water through the outlet conduit. The pump is preferably electrically operable. 
         [0008]    The first and second time periods commence simultaneously. For example, a user may operate a switch or depress a button in order to both open the valve and operate the ultra violet radiation source. Where a pump is provided, the pump is preferably operable to draw residual water present in the outlet conduit from the outlet conduit to the container. The pump may operate in this manner during periods when the ultra violet radiation source is illuminated and ensures that any water that may have been sitting in the outlet conduit is removed therefrom and re-sterilised. The device preferably has a standby mode whereupon the pump periodically operates to draw residual water from the outlet conduit In the standby mode the ultra violet radiation source may operate periodically to sterilise water present within the container. 
         [0009]    The device preferably includes a further container for untreated water which is in fluid communication with the inlet conduit. The further container may be filled with untreated water from any appropriate source such as, for example, a tap or faucet. The further container is preferably positioned above the container and may be at least partially received within the container. The further container is preferably arranged to supply water to the container by gravity. Both containers may be provided within a protective casing which serves, in use, to locate the containers in the correct position relative to one another. The containers are advantageously removable from the casing and, where appropriate, each other to facilitate cleaning. 
         [0010]    The filter means is preferably mounted to the further container and may comprises a replaceable casing containing filter media. The outlet conduit may comprise a flexible plastics tube. 
         [0011]    In a preferred embodiment the valve is electrically operable and is biased to a closed position. 
         [0012]    The device preferably includes a removable jug into which said outlet opens and into which filtered and sterilised water can be dispensed. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0013]      FIG. 1  shows a schematic cross-sectional view of a water filtration and sterilisation device according to the present invention; and 
           [0014]      FIG. 2  shows an external perspective view from above and to one side of a water filtration and sterilisation device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    An embodiment of the present invention with reference to the accompanying drawings in which:  FIG. 1  shows a schematic cross-sectional view of a water filtration and sterilisation device according to the present invention; and  FIG. 2  shows an external perspective view from above and to one side of a water filtration and sterilisation device according to the present invention. 
         [0016]    Referring firstly to  FIG. 1  there is shown a water filtration and sterilisation device generally designated  10 . The device includes a casing  12  within which there are provided upper and lower containers  14 , 16 . Advantageously the upper container  14  has a volume which is substantially equal to that of the lower container  16 . The casing  12  may be provided with a removable lid (not shown) which covers and closes the upper container  14 .  FIG. 1  shows the containers  14 , 16  being positioned one above the other. In an alternative embodiment the upper container  14  may be nested within the lower container  16  in the same manner as a conventional water filter jug. The base  18  of the upper container  14  is provided with a recess  20  within which there is provided a removable filtration cartridge  22 . The filtration cartridge  22  contains a filtration medium which, in use, removes particulate matter, chemicals and metals from water passing therethrough. 
         [0017]    The recess  20  is provided with an outlet conduit  24  which permits fluid passing through the cartridge  22  to pass to the lower container  16 . Within the outlet conduit  24  there is provided a valve  26  which is operable to open and close the outlet conduit  24  and thereby selectively permit or prevent the flow of water from the upper container  14  to the lower container  16 . The valve  26  is biased to a closed condition and is electrically movable to an open condition by a controller  28  as will be described in greater detail below. 
         [0018]    Within the lower container  16  there is provided a short wave (UVC) ultra violet lamp  30 . The lamp  30  is operable by the controller  28  as will be described in greater detail below. The base  32  of the lower container  16  is provided with an outlet  34  which is in fluid communication with an outlet conduit  36  which terminates at a spout  38 . The outlet conduit  36  may comprise a flexible plastic tube. Within the outlet conduit  36  between the lower container outlet  34  and the spout  38  there is provided an electrically operable pump  40 . The pump  40  is operable to move water from the lower container  16 , through the outlet conduit  36  to the spout  38 . The pump  40  is also operable in the reverse direction to return water from the outlet conduit  36  to the lower container  16 . The pump  40  may be operated by a user depressing a pump switch  42 . The pump  40  may also be operated by the controller  28 . The operation of the pump  40  will be described in greater detail below. The pump  40  may be considered to be optional and is necessitated by the provision of the spout  38  at height which is above that of the lower container  16 . In an alternative embodiment, liquid may be removed from the lower container  16  under the influence of gravity. In such an embodiment the outlet conduit  36  may be provided with a user operable valve to control the flow of liquid through the outlet conduit  36 . 
         [0019]    The spout  38  is positioned so as to supply water from the lower container  16  to a receptacle such as a jug  44 . 
         [0020]    In use, a volume of water, such as tap water, is introduced into the upper container  14 . The water is prevented from passing through the filtration cartridge  22  to the lower container  16  by the valve  26  which is initially in the closed position. The water is retained in the upper container  14  until an actuation switch  46  is depressed by the user. The depression of the actuation switch  46  causes the controller  28  to move the valve  26  to the open position and thereby permit water to flow from the upper container  14  to the lower container  16  through the filtration cartridge  22 . 
         [0021]    The controller  28  simultaneously operates the pump  40  in the reverse direction for a short time period, and operates the lamp  30  to sterilise water contained in the lower container  16 . The pump  40  is operated in the reverse direction so as to draw back into the lower container  16  any water which may be contained within the outlet conduit  36 . The casing  12  may be provided with an indicator (not shown), such as an LED, which illuminates to indicate that the lamp  30  is active and hence ultra violet sterilisation of water within the lower container  16  is taking place. In this state the device  10  maybe considered to be in a ‘cleaning’ mode. 
         [0022]    The controller  28  may maintain the valve  26  in the open position for a set time period. The time period is chosen so as to ensure that all of the water introduced into the upper container  14  is able to pass into the lower container. For example, the time period may be in the region of five minutes. In an alternative embodiment, the upper container  14  may be provided with a level or weight sensor which is able to determine the volume of water introduced into the upper container  14 . The sensed volume may then be utilised by the controller  28  to calculate the time period for which the valve  26  remains open. 
         [0023]    The controller  28  operates the lamp  30  for a time period which is greater than the time period for which the valve  26  is kept open. As before, the controller  28  may operate the lamp  30  for a set time period, for example eight minutes. 
         [0024]    Alternatively, the controller  28  may operate the lamp  30  for a time period which is calculated in response to the volume of water which is determined to have been introduced into the upper container  14 . 
         [0025]    Once the lamp  30  has been operated for the desired time period, the controller  28  switches off the lamp. The water in the lower container  16  is thus ready to be dispensed. The LED indicator may illuminate in a different colour to that of the ‘cleaning’ mode to indicate to the user that the water is ready to be dispensed. A user can dispense the water from the lower container  16  to the jug  44  by depressing the pump switch  42  to operate the pump  40 . The lower container  16  can be provided with a sensor in order to sense presence to water therein. In the event that a user does not immediately dispense the water from the lower container  16 , or dispenses only a portion of the water, the controller  28  causes the lamp  30  to illuminate periodically, for example every thirty minutes or so, so as to maintain the sterility of the water in the lower container  16 . The controller  28  preferably also operates the pump  40  in the reverse direction to return any water in the outlet conduit  36  to the lower container  16 . In this mode the device  10  may be considered to be in a ‘standby’ mode. Once the lower container  16  has been emptied the controller  28  is reset ready for the next volume of water to be introduced into the upper container  14 . 
         [0026]    Referring now to  FIG. 2  there is shown an exterior view of an embodiment of the water filtration and sterilisation device  10 . Features described above with reference to  FIG. 1  are identified with like reference numerals. The casing  12  is provided with a base  48  having a seat  50  upon which the jug  44  may rest. The casing  12  is further provided with a removable lid  52  which, when removed, permits access to the upper container  14 . The upper region of the casing  12  further includes a projection  54  which overlies the top of the jug  44  and within which the spout  28  is provided. The pump switch  42  is positioned below the projection  54  and adjacent the spout of the jug  44 . The pump switch  42  can thus be operated by contact with the jug spout. The lower region of the casing  12  is provided with a water level gauge  56  which indicates the water level within the lower container  16 .