Abstract:
A water tap is shown, employing a spherical sealing member which is urged into a sealing position by water pressure. The sealing member may be displaced centrally into the water flow in order to permit flow of water around the sealing member and through the tap.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a domestic water tap It is particularly envisaged for use as a garden water tap, or a tap mounted on an exterior wall of a building. It will be understood that used in this specification the term ‘tap’ takes on its British meaning, being equivalent to the American term ‘faucet’. 
     BACKGROUND TO THE INVENTION 
     Many domestic garden water taps employ a compression-type valve, whereby the turning of a tap handle forces a disc washer or jumper valve onto a valve seat, thus preventing the flow of water through the valve seat. Such valves are mechanically simple, cheap, and reliable. 
     As the valve ages, the washer and the valve seat both deteriorate. This can cause leakage of water though a closed tap. In order to prevent this, where the deterioration is minor, the valve can generally be closed by additional tightening of the handle. 
     Such tightening can be difficult for those without sufficient strength, such as the aged or infirm. In order to overcome this problem, there are several mechanical devices available to assist the aged or infirm in the opening and closing of tap valves. Often, however, the use of these devices can be both cumbersome and inconvenient. 
     Additionally, the deterioration requires relatively frequent replacement of worn washers. When washers are not replaced, wastage of water due to tap leakage can be significant. 
     It is desirable to provide a garden tap which can be readily operated by the aged or infirm without the need for additional mechanical assistance. Such a tap should readily close, without a propensity for leakage. It should also be arranged such that the degree of opening can be easily adjusted, in order to vary the flow rate of water passing through the tap. 
     The present invention seeks to meet these desiderata. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a water tap for use in regulating the flow of water delivered under pressure, the tap including a valve seat, a sealing member, and an activating rod, whereby the tap is movable between a closed position in which the water pressure urges the sealing member into engagement with the valve seat, thus preventing the flow of water through the tap, and an open position in which the activating rod urges the sealing member away from the valve seat, thus allowing flow of water through the tap, characterised in that the sealing member has a density less than water, and in that the activating rod is arranged to act through a centroid of the sealing member and to urge the sealing member into a position substantially centrally of the resulting water flow. Advantageously, this arrangement permits the sealing member to maintain a position centrally of the water flow due to an application of Bernoulli&#39;s principle. As a result, the degree of displacement of the sealing member from the valve seat can be readily controlled, thus allowing for easy adjustment of the rate of water flow. 
     It is preferred that the sealing member be spherical. This means that the orientation of the sealing member can vary without affecting its ability to readily seal. 
     In a preferred embodiment, the activating rod is connected to a handle, mounted in a threaded arrangement at an outer end of the tap, whereby rotation of the handle causes axial movement of the activating rod. This allows for easy adjustment of the action of the rod against the sealing member. 
     The sealing member may, be located within a receiving compartment of the tap, the receiving compartment having a water inlet axially opposed to the valve seat, the water inlet being sized so as to prevent the passage of the sealing member in the event of a loss of water pressure. 
     Searching on behalf of the applicant has revealed previous valve designs using fluid pressure to hold a sealing ball in position. These include U.S. Pat. Nos. 4,273,310, 4,667,349, 4,562,865 and 5,037,062. All of these arrangements act to displace a spherical member laterally of a valve seat, rather than into the fluid flow as in the present invention. As such, they are all ‘on/off’ valves, without the ready ability to control the flow of fluid through the valve through the use of Bernoulli&#39;s principle. 
     U.S. Pat. No. 6,006,784 does disclose a spherical sealing member which is displaced into the fluid flow. Nonetheless, the arrangement described in this patent is also an ‘on/off’ valve, with no application of Bernoulli&#39;s principle to allow for adjustment of fluid flow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It will be convenient to further describe the invention with reference to preferred embodiments of the water tap of the present invention. Other embodiments are possible, and consequently, the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings: 
         FIG. 1  is a cross-sectional schematic view of a water tap in accordance with the present invention, shown in a closed position; and 
         FIG. 2  is a cross-sectional schematic view of the tap of  FIG. 1 , shown in an open position. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     In accordance with the present invention there is shown a water tap  10 . The water tap  10  includes a water inlet  12  arranged to be fluidly connected to a water main (not shown), and a water outlet  14 . The water outlet  14  is shown as a ‘snap-fit’ hose connection, but it will be appreciated that other arrangements, such as a common externally threaded outlet, may be employed. 
     In the embodiment shown, the water inlet  12  and the water outlet are oriented perpendicularly to each other. Water passing through the tap  12  thus enters in a first water flow direction, aligned with the water inlet  12 , and exits in a second water flow direction, aligned with the water outlet  14 . 
     It will be useful to describe the arrangement of the tap  10  with respect to a central tap axis  16 . This axis is defined as parallel to the first water flow direction. 
     The tap  10  includes a receiving compartment  18  and an elbow portion  20 , the arrangement being such that water flows in turn through the water inlet  12 , the receiving compartment  18 , the elbow portion  20  and the water outlet  14 . Each of the water inlet  12 , the receiving compartment  18  and the elbow portion  20  are located along the central tap axis  16 . 
     The receiving compartment  18  is formed by a first frusto-conical portion  22 , a central cylindrical region  24 , and a second frusto-conical portion  26 , each of which has its axis along the central tap axis  16 . The arrangement is such that the radius of the central cylindrical region  24  is equal to the base radius of the first and second frusto-conical portions  22 ,  26 . The first frusto-concial portion  22  tapers away from the central cylindrical region  24  to a first circular aperture  28 . The second frusto-conical portion  26  tapers away from the central cylindrical region  24  towards a second circular aperture  30 . 
     A sealing member in the form of a spherical ball  32  is located within the receiving compartment  18 . The spherical ball  32  has a radius greater than that of the first and second circular apertures  28 ,  30 , but less than that of the central cylindrical region  24 . The ball  32  is thus contained within the receiving compartment  18 . 
     The tap  10  includes an activation means in the form of a handle  34 . The handle  34  is located along the central tap axis  16 , at an end remote from the water inlet  12 . This is in contrast to a traditional compression-type garden tap, where the handle is located above the water outer outlet  14 . 
     The handle  34  is connected into a body of the tap  10  by means of a threaded connection (not directly shown), such that revolution of the handle  34  is translated into axial movement along the central tap axis  16 . 
     An activating rod  36  extends from a base of the handle  34  through the elbow potion  20 , along the central tap axis  16 . 
     When the tap is in a closed position, as shown in  FIG. 1 , water is supplied through the inlet  12  under mains water pressure. This water pressurizes the receiving compartment  18  to mains pressure. The pressure acts against the ball  32 , pushing it against the second frusto-conical portion  26 . This seals the receiving compartment  18  from the elbow portion  20 , and prevents the flow of water through the tap  10  to the water outlet  14 . The second frusto-conical portion  26  thus acts as a valve seat, against which the ball seals. 
     When the tap  10  is to be opened, the handle  34  is turned, causing the activating rod  36  to move towards the ball  32 . The activating rod  36  contacts the ball  32  along the central tap axis  16  (thus in a radial direction, through the ball&#39;s centroid). Further turning of the handle  34  forces the ball  32  towards the first circular aperture  28 , and releases the contact of the ball on the second frusto-conical portion  26 . 
     Water will then flow around the ball  32 , and through the second circular aperture  30 , the elbow portion  20  and the water outlet  14 . This flow of water will cause a corresponding drop of pressure around the sides of the ball  32 , according to Bernoulli&#39;s principle. This will cause the ball to remain centered along the central tap axis  16 , as the water pressure will act to self-correct any lateral movement of the ball  32 . This position is shown in  FIG. 2 . 
     The flow rate through the tap will be determined by the minimal cross sectional area created between the ball  32  and the second frusto-conical portion  26 . This will be proportional to the distance traveled by the activating rod  36 , with area=2πr. sin 2 α.d, with r being the radius of the ball  32 , α being the angle of the second frusto-conical portion  26  to the central axis  16 , and d being the distance traveled by the activating rod  36 . 
     In order to close the tap, it will simply be necessary to turn the handle in the other direction until the rod is no longer acting against the ball. Water pressure will cause the ball to return to the position of  FIG. 1 . As the tap is closed by the removal of an applied force to the ball, rather than the provision of one, the degree of force required to close the tap is relatively small. 
     It is preferred that the ball  32  be formed from a material less dense than water. This will ensure that water pressure acts on the ball  32  to its fullest extent, both in sealing in the closed position and in maintaining lateral orientation in the open position. 
     It will be understood that one way in which the arrangement of the embodiment shown differs from a conventional compression-type tap is that the valve seat is located in the first water flow path, rather than the second. For this reason, the simplest arrangement is to have the handle  34  located along the main tap axis  16 . It will be appreciated that the invention could be applied with a different geometry, such as a handle located above the water outlet  14  or even the valve seat within the second water flow path. Such variations are considered to be within the scope of the present invention. 
     Further modifications and variations as would be apparent to a skilled addressee are similarly deemed to be within the scope of the present invention.