Abstract:
An overflow device for use with sinks and the like is described. The overflow device comprises a body adapted to be positioned adjacent the exterior of a sink bowl, the body having an inlet and an outlet joined by an inverted-U siphon passage, and a vent adapted to communicate ambient air to the top of the siphon passage, the vent being arranged to close when water level in the sink reaches a predetermined level. In at least one embodiment the vent has no moving parts.

Description:
FIELD OF THE INVENTION 
     This invention relates to a concealed overflow device for use with sinks and the like. 
     The invention will be particularly described herein with reference to sinks, but it is to be understood that the invention may be used with other plumbing installations such as basins and baths, and the expression “sinks and the like” is used herein to include all such applications. 
     BACKGROUND TO THE INVENTION 
     A sink conventionally has an overflow which determines the maximum level to which water can rise in the sink bowl. Usually, the overflow is in the form of an opening in the wall of the bowl, the opening being connected to the waste pipe either by means of a channel formed in the body of the sink itself or by means of a flexible hose interconnecting an overflow terminal and a terminal on the waste system. 
     Such overflow systems are simple and well understood, but they do have some disadvantages. An overflow channel within the sink body adds complexity to the structure and to the manufacturing process. A separate flexible hose arrangement uses a number of components and can be awkward to install and maintain. In addition, the waste opening in the wall of the sink bowl presents potential hygiene problems and can be difficult to clean. 
     It has hitherto been proposed to provide an overflow which is concealed, in the sense that there is no overflow opening in the wall of the bowl, and no overflow arrangement is visible to the user. Prior proposals, however, have relied on the use of valves in various forms, with consequent complexities in manufacture and potential reliability problems. 
     There is therefore a need for a concealed overflow arrangement of simple construction and operation. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides an overflow device for use with sinks and the like, the overflow device comprising: 
     a body adapted to be positioned adjacent the exterior of a sink bowl, the body having an inlet and an outlet joined by an inverted-U siphon passage, and 
     an air valve adapted to communicate ambient air to the top of the siphon passage, the air valve being arranged to close when water level in the sink reaches a predetermined level. 
     In at least one embodiment of the present invention, an overflow device is provided which can be fitted to two a sink, basin bath or the like and is adapted to selectively communicate air to a siphon passage permitting the overflow device to move between a siphonic state and a non-siphonic state, in the siphonic state the siphon draining the water out of the bath sink or basin or the like to below a predetermined level. 
     The inverted U-shaped siphon passage may comprise a first passage and a second passage, the first and second passages being divided by a passage member. 
     In a particularly preferred form of the invention, the air valve has no moving parts. 
     To this end, the air valve may comprise a vertical passage at the top of which is located an entry port separated from the top of the siphon passage by an inverted weir. 
     The air valve may comprise the entry port. 
     The entry port may be located on the overflow device body. 
     The body may define an upper portion, the upper portion in use defining the point of highest elevation of the overflow device. By this it is meant that when the overflow device is in a working position, the point of highest elevation is at or adjacent the maximum height water can rise to within the overflow device. 
     The entry port may be located on the body upper portion. 
     The entry port may be located at or adjacent the point of highest elevation of the overflow device. 
     The entry port may be located at or adjacent the highest elevation of the highest elevation point of the overflow device. 
     In use, the entry port may lie in a substantially horizontal plane. 
     In this embodiment, the entry port may be on an upper surface of the body. 
     The inverted weir may extend downwardly from the upper end of the vertical passage. 
     The inverted weir may extend downwardly such that the lowest point of the weir, in an in use configuration is below and upper end of the passage member. Such an arrangement ensures that the air valve is sealed by the rise of water prior to the water cascading over the passage member to establish siphonic flow conditions. If this was not the case then air would be admitted into the overflow device by the air valve prior to the establishment of a siphonic flow condition, potentially preventing the establishment of the condition. 
     The air valve may comprise an exit port, the exit port permitting air from the entry port to enter the siphon passage and breakdown siphonic flow. 
     The exit port may lie in a plane perpendicular to an entry port plane. 
     The entry port and the exit port may define a flowpath therebetween. 
     The flow path may be convoluted. 
     When the air valve is open, ambient air may be sucked through the entry port. 
     The body may further define a lower portion, the upper and lower body portions cooperating to define the inverted U-shaped siphon passage and the air valve vertical passage. 
     The upper and lower body portions are arranged telescopically. 
     In one embodiment, the upper and lower body portions are telescopically adjustable in height. 
     The upper and lower body portions may be sealingly connected. Sealingly connecting the upper and lower body portions prevents the egress of water from the overflow. 
     The body portions may be sealingly connected by a sealing arrangement. 
     The sealing arrangement may comprise a barrier. 
     The barrier may be a seal. 
     A barrier may be elastomeric seal. Alternatively or additionally, the barrier may be a gel or any type of sealing arrangement. 
     The elastomeric seal may be an O-ring seal. In other embodiments the elastomeric seal may be an edge seal. 
     One of said upper and lower body portions may be provided with integrally formed blade seals engaging with the other of said upper and lower body portions. This avoids the use of O-rings or the like. 
     The lower body portion may define the inlet and the outlet. 
     The inlet and outlet may be provided with swivel elbows to facilitate installation. 
     The overflow device may further comprise an air vent, the air vent adapted to vent air from the overflow device and/or pipework associated with overflow device. 
     From another aspect the invention provides a waste and overflow arrangement comprising a device as defined above in combination with a sink outlet waste fitting; the waste fitting having a sealing member movable between an open position allowing water to drain from the sink and a closed position retaining water within the sink; the waste fitting having a first fluid connection above the sealing member and a second fluid connection below the sealing member; the arrangement further comprising a first fluid conduit between the first fluid connection and the overflow device inlet and a second fluid conduit between the second fluid connection and the overflow device outlet. 
     Preferably the first and second fluid conduits are respective pipes and the first and second fluid connection and the overflow device inlet and outlet each comprises a pipe connector. 
     In certain embodiments, the waste fitting includes an air admission means in communication with the interior of the waste fitting below the sealing member. 
     A further aspect of the invention provides a waste fitting for use in the above arrangement, comprising a body adapted to be attached to a drain hole in a sink or the like; a sealing member movable within the body between an open position allowing water to drain from the sink and a closed position retaining water within the sink; the waste fitting having a first fluid connection above the sealing member and a second fluid connection below the sealing member. 
     In certain embodiments, the waste fitting includes a further connection below the sealing member for fitting an air admission means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example, with reference to the drawings, in which: 
         FIG. 1  is a perspective view of one embodiment of overflow arrangement according to the present invention; 
         FIG. 2A  is a similar view illustrating operation in a drain mode; 
         FIG. 2B  is a similar view illustrating operation in an overflow mode; 
         FIGS. 3A, 3B, 3C, 3D, 3E, and 3F  show a front cross-sectional view of part of the apparatus, showing a sequence of operations; 
         FIG. 4  is a view similar to  FIGS. 3A, 3B, 3C, 3D, 3E, and 3F  showing a preferred sealing arrangement; 
         FIG. 5A  is a perspective view of a modified embodiment; 
         FIG. 5B  is a plan view corresponding to  FIG. 5A ; and 
         FIGS. 6 and 7  are cross-sectional views of further modified embodiments. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a waste and overflow assembly for a sink or the like comprises a waste fitting  10  and an overflow device  12  connected by two pipes  14  and  15 . 
     The waste fitting  10  in this embodiment is of the type having a basket strainer and integral sealing plug, and comprises a flange  16  and an underbody  18  which screw together to engage with a sink opening. A strainer basket  20  is mounted on a movable stem  22  which also carries a sealing disc  24  which can be engaged against the underbody  18  to close the waste fitting  10 . 
     The underbody  18  has a first boss  26  above the sealing disc  24  and a second boss  28  beneath the sealing disc  24 , in which the pipes  14  and  15  are secured by backnuts  30  and seals  32 . 
     The overflow device  12  comprises a lower body portion  34 , a telescopic upper body portion  36  comprising a passageway portion  37  and a cap  38 , and will be described in greater detail below. The lower body  34  is provided with removable covers  48  to allow access to clear blockages. 
       FIG. 2A  shows the overflow device  10  in a draining mode, in which the strainer basket  20  and sealing disc  24  are in a raised position. In this mode water in the sink passes directly to the drain.  FIG. 2B  shows the overflow device  10  in overflow mode. Here, the sealing disc  24  is engaged to retain water in the sink. If the water rises above a predetermined level in the sink it overflows via the pipes  14  and  15  and the overflow device  10  to drain beneath the sealing disc  24 , as will now be explained more fully. 
     Referring to  FIGS. 3A, 3B, 3C, 3D, 3E, and 3F , the lower body portion  34  and the upper body portion  36  together form three passages A  60 , B  62  and C  64 . Passages A  60  and B  62  are separated by a passage member  63  and together with an interior volume of the cap  38  form a siphon. Passage B  62  and passage C  64  are separated by a further passage member  65 . Passage C  64  together with the remainder of the cap  38  form a non-mechanical air valve (i.e. a valve with no moving parts) having an air entry port  40  and an inverted weir  42 . The inverted weir  42  extends downwardly from an upper end  66  of the passage C  64  such that its lowest point  68 , in use, is below an upper end  70  of the further passage member  65 . The sequence of events shown in  FIGS. 3A, 3B, 3C, 3D, 3E, and 3F  will now be described. 
     First the water level in passages B  62  and C  64  mirrors the level in the sink bowl ( FIG. 3A ). In  FIG. 3B , the water level reaches the predetermined overflow level. Water begins to drain into passage A  60 . The level in passage C  64  continues to match the level in the sink bowl. As the level in the sink bowl increases (seen in tube C  64 ), the air valve  40  is shut off. Drainage speed now increases due to the syphonic effect on the water in passage B  62 . Referring to  FIG. 3D , a syphon is fully formed and drainage speed increases to its maximum level (in a preferred example, 19 liters/min). Once the syphonic flow is set up the level in the basin sink bowl starts to drop, the level in passage C  64  dropping, continually matching the level in the sink bowl, allowing the air valve  40  to open ( FIG. 3E ).  FIG. 3F  shows air entering the overflow chamber, breaking the siphon. 
     It will be noted that both the feed pipe  14  and the return pipe  15  remain open at all times regardless of mode of operation. No valves are required in these parts. 
     Referring to  FIG. 4 , in the preferred embodiment the upper body  36  telescopes within the lower body  34  such that the height of the overflow device  12  is adjustable. The upper body  36  is moulded with blade seal rings  44  which eliminates the need for rubber seals such as O-rings.  FIG. 4B  shows the cross-section of the blade seal rings. In alternative forms of the invention, the telescopic adjustment may be dispensed with, and the overflow device  12  formed as a rigid unit of fixed length. 
       FIG. 5  shows a modified embodiment in which the pipes  14  and  15  are attached to the overflow device  12  via swivel elbows  46 . This allows the assembly to be manoeuvred to avoid obstacles under the worktop such as taps or pipework.  FIG. 5B  indicates the range of angular variation which can be achieved. 
     The embodiments described above can suffer a problem when used with certain traps and U-bends in the downstream waste system, in that when the waste plug is closed an air bubble or air lock can form between the overflow device and the traps or U-bend, impeding or preventing flow from the overflow device. The embodiments of  FIGS. 6 and 7  overcome this. 
     In  FIG. 6 , an air inlet is provided in the form of a standpipe  50  which admits air into the underbody  18  below the sealing disc  24 , thus preventing the formation of an air bubble in the downstream waste system. The standpipe  50  extends above the level of the cap  38  to prevent overflow of water from it. 
     The same function is performed in  FIG. 7  by a one-way air admission valve  52 ; such valves are well known per se. 
     The invention thus provides a concealed overflow arrangement which can be achieved without the use of moving parts and will thus be simple to manufacture and reliable in operation.