Abstract:
A plug which is insertable into a outlet from a vessel, to seal the vessel so that it may hold liquid. To prevent overflow, the plug has an in-built valve which automatically opens when it experiences a predetermined threshold pressure. The threshold pressure can be adjusted to cater for vessels of differing size.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a plug for closing a liquid outlet. For example, it relates to a plug which acts as a stopper for closing drainage outlets from bathroom vessels (e.g. sinks, baths, etc.)  
       BACKGROUND OF THE INVENTION  
       [0002]     Fixed vessels (e.g. sinks, baths etc.) for holding liquid generally have an outlet e.g. positioned at the lowest point thereof to allow used liquid to drain away e.g. to a main sewer. In order for the vessel to hold liquid without draining occurring it is necessary to seal the outlet. Sealing can be achieved by stopping the outlet using a rubber disc. The disc can be attached to the vessel by a chain to facilitate removal. Alternatively, the disc can be part of an in-built mechanism operable by a lever, commonly known as a pop-up waste. By sealing the outlet, the risk of overflow of the vessel is created. To avoid this problem, extra outlets are provided in vessels at a certain height from the lowest point. This means that liquid will flow out of these outlets when the height in the vessel is above a predetermined amount. These so-called “overflows” remove the risk of flooding caused by overfilling the vessel.  
         [0003]     However, overflow channels have disadvantages. Firstly, they are difficult to clean because by their nature they must include a relatively long enclosed channel. They easily become dirty and can be unsightly. Secondly, they are relatively difficult to manufacture. Traditional bathroom/kitchen vessels are made from china, and the formation of a self-contained channel presents certain design and manufacturing limitations.  
         [0004]     Furthermore, more modern vessel designers use different materials, some of which are transparent (e.g. glass). Overflow channels are not provided in these vessels because of the problem of cleaning and unsightliness mentioned above. There is therefore a risk of overfilling these vessels.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an aim of the present invention to obviate the need for an overflow channel.  
         [0006]     At its most general, a first aspect of the invention provides a plug, e.g. for acting as a stopper for a drainage outlet in a vessel (e.g. a bathroom vessel), having a pressure-sensitive valve arranged to cause the plug to open automatically when a certain pressure e.g. due to a given weight of liquid in the vessel is reached. The plug therefore acts as both a sealing element and a safety (e.g. overflow prevention) mechanism. This allows the vessel to possess only one drainage outlet.  
         [0007]     Thus, according to the first aspect of the invention, there may be provided a combination of a vessel having an outlet and a plug which is insertable into and removable from the outlet to close the vessel thereby allowing it to hold liquid, the combination having:  
         [0008]     a conduit for locating in the outlet such that liquid cannot pass through the outlet without also passing through the conduit; and  
         [0009]     a valve located in the conduit,  
         [0010]     wherein in use the valve is arranged to maintain a first configuration in which the conduit is sealed to prevent liquid from passing therethrough unless pressure on the valve reaches a threshold value, whereupon the valve is arranged to adopt a second configuration in which the conduit is open to allow liquid to flow therethrough.  
         [0011]     Preferably, the conduit and valve are included together in the plug, i.e. the valve may be permanently located in the conduit. Preferably, the plug includes sealing means for sealing the conduit in the outlet. Thus, in use, the plug is placed into the outlet e.g. in the conventional way. The plug may be attached to the vessel by a chain to facilitate removal, or it may be a separate free-standing body. Alternatively, it may be implemented using the conventional pop-up lever technique. When the plug is located in the outlet, the sealing means preferably abuts the interior of the outlet to seal the conduit therein so that the only way liquid (e.g. water) can exit the vessel through the outlet is via the conduit. Usually, a pipe (e.g. U-bend) extends away from the outlet to the drain. The conduit is preferably shaped to fit snugly in the pipe.  
         [0012]     In its rest state, the conduit is preferably sealed by the valve. Thus, when the plug is initially placed in the outlet, the outlet is sealed and the vessel can be filled with liquid. As the vessel fills with liquid, the pressure caused by the weight of liquid acting on the valve increases. When the pressure reaches a predetermined value (i.e. a threshold value), it triggers the opening of the valve, thereby allowing water to flow through the conduit, i.e. out of the vessel through the outlet. By selecting the threshold value suitably, the valve may be opened by pressure from a height of water lower than the rim of the vessel so overflow can be avoided.  
         [0013]     Preferably, the valve is biased into the first configuration, the biasing force being selected so that pressure at and above the threshold value overcomes it (i.e. acts against the biasing force to cancel it out) to cause the valve to adopt the second configuration. The biasing force may be applied using a spring. Thus, the plug occupies the first configuration (e.g. sealed conduit) in its rest state.  
         [0014]     Preferably, the valve includes a sealing element movable relative to the conduit between a first position where the valve is in the first configuration and a second position where the valve is in the second configuration. The sealing element therefore preferably effects sealing of the inside of the conduit.  
         [0015]     Preferably, the sealing element is movable along the axis of the conduit. The sealing element may include a sleeve slidably mounted on a boss which is fixed relative to the conduit in use. The sleeve may be biased against the boss, e.g. using a spring, to urge the sealing element into the first position.  
         [0016]     Preferably, the valve includes a plate whose periphery seals against the inside of the conduit in the first configuration. The plate may be part of the movable sealing element. The plate may have an o-ring or other suitable sealing agent around its periphery to ensure sealing integrity. The conduit may have a constricted portion against which the plate, e.g. the periphery of the plate or the o-ring, abuts to form a seal in the first configuration. The arrangement may be such that the plate has an area less than the cross-sectional area of the conduit, but the conduit includes an inwardly projecting ridge which prevents movement of the plate past it. The plate is therefore preferably biased against the ridge to seal the conduit in the first configuration, but suitable pressure can push it away from the ridge to allow liquid to escape past the gap between the ridge and plate in the second configuration. Preferably, the conduit is substantially cylindrical and the plate is a disc. The gap for liquid flow may then have an annular shape in the second configuration.  
         [0017]     Preferably, the plug includes an adjuster for adjusting the valve so that it reacts to a different threshold value. In other words, the pressure at which the valve opens can be selected. The adjuster may be arranged to alter the biasing force, e.g. by varying the strength of the spring. This may be achieved by permitting the axial position of the boss, which is fixed in use, to be varied, e.g. through a screw adjustment. The adjuster permits the plug to be operable in a variety of vessel sizes, since the valve can be made to react to a variety of pressures i.e. responsive to variety of different liquid weights (heights).  
         [0018]     When used with a pop-up lever, the plug preferably includes a height adjusting mechanism to enable the outlet to be properly sealed when closed by the plug.  
         [0019]     Preferably, the sealing means includes a protruding ridge around the outside of the conduit, e.g. to abut the edges of the outlet to form a seal. The ridge may include an o-ring or other suitable sealing agent to ensure integrity of the seal. The ridge may be at one end of the conduit so that the plug can be substantially completely inserted into the outlet to lie flush with the vessel base. The conduit may protrude in use.  
         [0020]     Most vessels have liquid dispensing apparatus, e.g. taps located over the outlet. In a development of the present invention, the plug preferably includes a cover for shielding the valve. The cover is preferably separated (e.g. axially) from the conduit to allow liquid to flow under it onto the valve. The cover prevents liquid flow from the tap from directly impinging on the valve and accidentally causing it to adopt the second configuration. The cover is therefore preferably located over the mouth of the conduit, and may protrude above the outlet when the plug is fitted in use. The cover may be mushroom-shaped, i.e. it may have a rounded upper surface to deflect liquid incident thereon. The cover may be made of material selected to match the tap, e.g. metal, preferably stainless steel.  
         [0021]     The first aspect of the invention may alternatively be expressed as a plug which is insertable into and removable from an outlet from a vessel to close the vessel thereby allowing it to hold liquid, the plug having:  
         [0022]     a conduit for locating in the outlet;  
         [0023]     sealing means for sealing the conduit in the outlet such that liquid cannot pass through the outlet without also passing through the conduit; and  
         [0024]     a valve located in the conduit,  
         [0025]     wherein in use the valve is arranged to maintain a first configuration in which the conduit is sealed to prevent liquid from passing therethrough unless pressure on the valve reaches a threshold value, whereupon the valve is arranged to adopt a second configuration in which the conduit is open to allow liquid to flow therethrough.  
         [0026]     The plug may be made from any material, but is preferably made of plastic.  
         [0027]     An alternative solution to the problem which is a second aspect of the invention is also proposed. At its most general, the second aspect provides a pressure-sensitive valve for releasably closing a conduit, wherein the closing function of the valve can be manually overridden.  
         [0028]     Thus, according to the second aspect of the invention, there may be provided a stopper for controlling liquid flow through a conduit, the stopper including:  
         [0029]     a valve member mounted in the conduit, the valve member being urged into sealing contact with the conduit to prevent liquid flow therethrough; and  
         [0030]     override means arranged to move the valve member out of sealing contact with the conduit to allow liquid flow therethrough.  
         [0031]     Thus, the valve member may be movable between two positions. In a first position, it may be urged into sealing contact with the conduit whereby it acts essentially as a pressure-sensitive valve, i.e. when in use in the first position, the valve member maintains a first configuration in which the conduit is sealed to prevent liquid from passing therethrough unless pressure on the valve member reaches a threshold value, whereupon the valve is arranged to adopt a second configuration in which the conduit is open to allow liquid to flow therethrough. In a second position, the valve member may be positioned such that the conduit is open, and liquid can flow freely therethrough.  
         [0032]     The valve member is preferably urged by biasing means, e.g. a spring or over resilient biasing agent. Preferably, the valve member is biased against a base. The override means may move the valve member against the biasing force. However, it is preferred that the base itself is movable by the override means. In this case, the override means need not act against the biasing means; the entire valve mechanism (e.g. the valve member, biasing means and base) may be movable so that the valve member moves into and out of engagement with the conduit.  
         [0033]     The conduit in the second aspect may be a pipe leading away from the outlet of a vessel. In this case, the stopper may act as a plug for the vessel.  
         [0034]     Sealing contact may be achieved using a seal around the rim, e.g. protruding from the rim, of the valve member. The seal may be an o-ring or other suitable sealing agent. The seal may abut a inwardly projecting ledge in the conduit.  
         [0035]     The override means may include a lever, e.g. a manually operable lever, for moving the valve member. The valve member is preferably movable along the axis of the conduit.  
         [0036]     The override means may resemble a pop-up lever.  
         [0037]     Preferably, the valve member includes an adjuster for adjusting the biasing force and a height adjusting mechanism, e.g. when the override means includes a lever, as explained above with reference to the first aspect.  
         [0038]     In the second aspect of the invention, the means for overriding the pressure-sensitive valve, i.e. the overflow prevention mechanism, to allow liquid to flow freely through the conduit preferably moves the valve member as a whole in the same direction as the movement of the sealing means when pressure causes the valve to open. In contrast, in the first aspect of the invention, the plug is preferably opened by being moved in a direction opposite to the movement of the sealing means when pressure causes the valve to open. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]     Examples of the present invention is now described with reference to the accompanying drawings, in which:  
         [0040]      FIG. 1  shows a cross-sectional view through a plug which is a first embodiment of the invention, where the plug is located in the plug hole of a vessel in a closed configuration with its internal valve also being closed;  
         [0041]      FIG. 2  shows a perspective view of the plug shown in  FIG. 1 ;  
         [0042]      FIG. 3  shows the plug of  FIG. 1  where the internal valve is open;  
         [0043]      FIG. 4  shows the plug of  FIG. 1  in an open configuration;  
         [0044]      FIG. 5  shows a plug which is a second embodiment of the invention; and  
         [0045]      FIG. 6  shows a plug which is a third embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0046]      FIG. 1  shows a cross-sectional view through a plug  10  inserted in a plug hole (outlet)  6 , which is defined by sidewall  8 . The plug  10  has a cartridge  12  which has two pairs of opposing arms  13  which form an open cage-like structure. The arms  13  extend to the top of the cartridge  12 , which is shaped into an annular body  14  with a tapering external edge  15 . The annular body  14  forms a conduit and defines an aperture. An o-ring  16  is located in a recess  17  formed around the body  14 . The size of the body  14  and cartridge  12  is selected so that the plug can be inserted into a plug hole  6  such that the tapering edge  15  and o-ring  16  seal against the inner wall  8  of the plug hole  6 . This means the only route for liquid to flow out of the plug hole  6  in this configuration is through the inside of the annular body  14 , i.e. through the aperture. Once it has flowed through the annular body, the liquid escapes from the cartridge  12  through the gaps between the arms  13 .  
         [0047]     At the opposite end of the cartridge  12 , a boss  18  is fixed to the cartridge  12  by being threaded on to a ring member  20  which is held in place by the arms  13  of the cartridge  12 .  
         [0048]     A sleeve  24  is axially slidably mounted on a portion  25  of the boss  18  that projects above the ring member  20 . The sleeve  24  is an integral part of a depressible valve member  28  which is arranged to seal the inside of the annular body  14  to prevent liquid flow therethrough. The valve member  28  is urged away from the boss  18  by a spring  26  located in a space  27  above the portion  25  within the sleeve  24 . The inside of the annular body  14  is provided with a downwardly tapering surface  32 , and the valve member  28  has a corresponding chamfered surface  29  which is urged into sealing engagement with the surface  32 . The tapered surface  29  of the valve member  28  has an o-ring  30  located in a recess  31  for pressing against the surface  32  to ensure a good seal. The surface  32  has a projecting rib  33  for abutting against the o-ring  30 .  
         [0049]     Thus, at rest, the valve member  28  is urged upwards (in  FIG. 1 ) by the spring  26  so that it seals the inside opening of the annular body  14  and prevents liquid from passing through the cartridge  12 . Since the outside of the body  14  seals the plug hole  6 , this arrangement prevents liquid from flowing through the plug hole  6 , and therefore acts as a conventional plug.  
         [0050]     However, as liquid builds up on top of the valve member  28 , its weight acts against the spring  26 . At a threshold level, the weight of liquid will overcome the spring force and move the valve member  28  downwardly (in  FIG. 1 ), thereby creating a gap between chamfered surface  29  and tapering surface  32  so that liquid can escape through the cartridge  12 .  
         [0051]     To prevent liquid flow from taps or other liquid input means located over the plug hole  6  from impinging directly on the valve member  28  and thereby accidentally opening it due to the force of the flow, a cover  34  is attached to the cartridge  12 . The cover  34  has a convex upper surface for deflecting liquid incident thereon to reduce spray and splash back. The underside of the cover  34  is separated from the annular body  14  by a gap so that liquid can still enter the plug and act against the valve member  28 .  
         [0052]     A bolt  36  is attached to the boss  18  to adjust the vertical size (extent) of the plug  10 . The bolt  36  can be screwed into or out of the boss  18  using interface  38  to adjust the vertical distance between pop-up lever  50  and the annular body  14  to ensure that the cartridge  12  fits snugly into the plug hole  6  when the pop-up lever  50  is in a position which designates that the plug hole  6  is sealed by the plug  10 . Additionally, the boss  18  is vertically adjustable with respect to the ring member  20 . The boss  18  can be screwed into or out of the ring member  20 , which moves the portion  25  further into the sleeve  24 . This has the effect of reducing the space  27  and compressing the spring  26 , thereby increasing the spring force and requiring a larger weight of liquid to open the valve. In this way the plug  10  can be adjusted for vessels capable of holding liquid to different height levels.  
         [0053]      FIG. 2  shows the exterior of the plug  10 .  FIGS. 3 and 4  show the operation of the plug  10 .  
         [0054]     The arrangement shown in the drawings includes a pop-up lever  50  used for moving the plug  10  between an open configuration where the annular body  14  lies above the plug hole opening and a closed configuration where the annular body  14  seals against the sidewall  8  of the plug hole  6  as described above. The pop-up lever  50  is in a lowered position corresponding to the closed configuration in  FIGS. 1 and 3 , so the plug  10  seals against the sidewall  8  of the plug hole  6 . However,  FIG. 3  shows the plug  10  when a weight of liquid has forced the valve member  28  to move away from the annular body  14  (downwardly in  FIG. 3 ) to open the seal between the chamfered surface  29  and the tapering surface  32  to allow liquid to flow therebetween out of the plug hole  6 .  
         [0055]      FIG. 4  shows the pop-up lever in a raised position corresponding to the open configuration. Here the plug  10  is raised out of the plug hole  6  to allow liquid to flow out of the plug hole  6  through a gap between the annular body  14  and the sidewall  8  of the plug hole  6 .  
         [0056]      FIG. 5  shows an alternative embodiment of the present invention. In  FIG. 5 , a cartridge  112  and cover  134  are secured in fixed relation to the sidewall  8  of the plug hole  6 . An o-ring  116  is located in a recess  117  on the outer surface of the cartridge  112  and forms a seal with the inside of the sidewall  8 . Liquid can therefore only drain away through the inside of the cartridge  112 , via entrance openings  54 . The cartridge  112  is generally fixed in use, but may be removed, e.g. for cleaning.  
         [0057]     A valve member  128  is mounted within the conduit formed by the sidewall  8  of the plug hole  6 , where it is axially movable relative to the cartridge  112  by operation of the pop-up lever  50 . In its raised position, the pop-up lever  50  seals the plug hole  6  by pushing the valve member  128  into sealing contact with the cartridge  112 . The valve member  128  has an o-ring  130  located in a recess  131  which abuts the tapered side wall  129  of the cartridge  112 . The valve member  128  has a sleeve  127  which is spring loaded on to a boss  118  in a manner similar to that described above. This means that a given weight of liquid can overcome the spring force and cause the valve member  128  to move away from the cartridge  112  and thereby open the plug hole  6 , i.e. allow liquid to escape through a gap between the cartridge sidewall  129  and the valve member  128 .  
         [0058]     To ensure that the valve member  128  seals against the cartridge  112  with the same force each time the conduit is closed, a stop  52  is provided to limit the closing movement of the pop-up lever  50 . Thus, the pop-up lever  50  moves to the same position each time the conduit is closed. The spring strength is alterable by adjusting the axial position of screw  136 , which is threaded into the boss  118 . Altering the overall axial length of the valve member  128  affects how hard it is pushed against the cartridge  112  when the pop-up lever  50  is moved to its closed (raised) position.  
         [0059]     In its lowered position, the pop-up lever  50  permits the valve member  128  to fall away from the cartridge  112  under gravity, thereby allowing liquid to flow out of the plug hole  6  through a gap between the cartridge  112  and valve member  128 .  
         [0060]      FIG. 6  shows yet another embodiment of the present invention. The plug shown in  FIG. 6  works in an identical fashion to that shown in  FIG. 1 , and common parts are given the same reference numbers. The main difference between the plugs in  FIG. 1  and  FIG. 6  is that the seal formed by valve member  28  is located above the seal formed between the sidewall  8  and annular body  14  (i.e. o-ring  16 ). To achieve this, the downwardly tapering surface  32  with protruding rib  33  against which the chamfered surface  29  of the valve member  28  is urged into sealing engagement by spring  26  is provided on an inwardly protruding ring member  140  at the top end of annular body  14 . The ring member  140  is attached to cover  34  by a plurality of upstanding elements, which define entrance slots therebetween to permit liquid to impinge on the top surface of the valve member  28 .  
         [0061]     The configuration shown in  FIG. 6  permits the valve member  28  to be included in an upper part of the plug which is not constrained by the size (diameter) of the inner wall  8  of the plug hole  6 . This enables cartridges of different diameters to be manufactured (e.g. for different sizes of plug hole) whilst keeping constant the surface area of the valve member on which liquid impinges to open the valve.