A FLOW RESTRICTION DEVICE FIELD OF THE INVENTION This invention relates to a device and a method of reducing flow rates in larger diameter (e. g. 12mm) taps and cocks for the purpose of water conservation and particularly relates to a flow reducing valve cylinder insert which enables larger diameter (e. g. 12mm) cocks to operate with a smaller (e. g. 9mm) jumper valve thereby reducing excessive water consumption. The insert can incorporate particular innovative methods of low noise flow restriction in a conduit such as a water pipe by combining size reduction of the tap seat port, the incorporation of an advanced jumper valve and tangential restriction passages and ports. The flow reducing insert finds use in domestic, public and industrial fluid water taps and circuits where standard jumper valves deliver excessive flow rates. The insert can be a cartridge which is used to regulate fluid flow through a particular conduit.

BACKGROUND ART For water supplies, jumper valves are used to regulate the flow of water through a water pipe.

One common use of jumper valves is with screw down pattern taps and cocks which include a tap body having a fluid flow pathway extending there through, a valve seat located intermediate in the fluid flow pathway, a tap spindle which is moveable towards and away from the valve seat usually by rotation, with the tap spindle having a recess or bore located in the lower face, and a tap head which connects to the tap body and which houses the tap spindle. The tap head has an opening in the top through which an upper portion of the tap spindle extends and about which a handle is fixed to allow the tap spindle to be rotated in the tap head and towards and away from the valve seat.

This type of tap, referred to as a screw down pattern tap, is commonly used in domestic dwellings, public places and industrial facilities as water outlet taps and also as the mains water isolation cocks. The tap commonly has a 12mm bore.

Shut off valves which are commonly used with this type of tap

(otherwise known as a loose tap washer valves or more correctly, as jumper valves) include a disc like a seal which overlies the valve seat, and a stem which extends from the disc like seal and locates within the tap spindle.

Advancement of the tap spindle results in the seal being brought into the engagement with the valve seat thereby stopping fluid flow through the tap body.

One disadvantage with these 12mm cocks and taps is that the 12mm bore often allows far more water to pass than is required for many applications and they are difficult to regulate to economical flow rates. internal domestic taps used for shower recesses and hand basins are typically of 12mm capacity. These taps reach full flow rates of approximately 20 litres per minute within approximately one quarter to one half a turn of the handle. Frequently, the tap is opened well beyond an economical point of delivery and consequentially a considerable volume of water is routinely wasted. Flow rates of about 5-7 litres per minute for most shower recesses and 3-5 litres per minute for most hand basins are more than adequate, and without adequate flow control on these taps as much as 75% or about 15 litres per minute of the water is wasted.

Manually closing the aperture through which water must pass is of limited use in effective flow regulation, as water has a very low viscosity.

As the aperture closes, the low viscosity of the water will counteract this restriction by simply accelerating through the closing aperture thereby maintaining the flow rate. This makes manual regulation with a standard 12mm cock impractical. The apertures required to significantly restrict flow are quite small and this makes regulation of economic flow rate by the standard 12mm cock an impractical solution to this problem.

In the case of a shower recess, the water wastage is more extreme owing to the duration that a person having a shower tends to occupy, and also because much of the excessive flow misses the person in any case.

Some cocks such as bath or garden cocks are used to deliver water at a maximum rate, and in these cocks restriction of the flow rate may not be necessary for water conservation purposes.

Another disadvantage with many known flow restricting devices is the problem with noise caused by the creation of symmetric cavitation in the flow restriction device which causes a sound wave to be generated.

OBJECT OF THE INVENTION It is an object of the invention to provide an insert or device which can be placed in an otherwise conventional tap and which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice.

In one form, the invention resides in a flow restriction insert for a tap, the insert having a first sealing means to sealingly engage with a tap seat in the tap, an internal chamber, an inlet to allow fluid to flow into the chamber, an outlet to allow fluid in the chamber to flow out of the insert, and a tap seat in the chamber and between the inlet and the outlet, the tap seat having a diameter smaller than the tap seat of the tap thereby allowing a smaller diameter valve to control the fluid flow.

The insert can be formed from any suitable materials such as plastics, metals, composites thereof. The insert can be inserted into an otherwise conventional tap which means that tap modification or specially designed taps are not required.

In use, a tap can be broken open by removing the tap head.

The existing jumper valve is removed and the insert which is the subject of the invention is placed into the tap body such that the sealing means engages with the tap seat in the tap. A new valve can then be inserted into the insert and the tap head can be screwed back on with the existing tap spindle operating in the usual manner. Thus, an advantage of the invention is that no modification or specially designed taps are required.

The first sealing means is typically an O seal which sits over the tap seat in the tap. The sealing means is typically a removable O seal which can be fitted into an annular recess or channel in the insert to keep the O ring in place.

The insert is substantially hollow and has an internal chamber.

The internal chamber is in fluid communication with an inlet which allows fluid

(typically water) to flow into the chamber. The chamber is also in fluid communication with an outlet (which may be one outlet or a number of separate outlets) which allows water to flow out of the chamber and out of the insert. Fluid flowing through the outlet typically flows out of the tap mouth at a reduced rate.

A tap seat is provided in the chamber and between the inlet and the outlet. The tap seat may be an annular shoulder or ledge which is substantially planar and which can sealingly engage with a smaller diameter valve. This tap seat is configured such that a smaller diameter valve can be inserted into the chamber to regulate fluid flow through the chamber.

The smaller diameter valve may be that described in our earlier international patent application PCT/AU99/00199 the contents of which are incorporated herein by suitable cross-reference to form part of the present specification.

It is preferred that the outlet extends through a side wall in the chamber which means that the outlet is tangential to the chamber wall.

In order to further improve the flow restriction qualities, the inlet may be associated with a restriction means to reduce the flow of fluid passing into the chamber. The restriction means may be in the form of a diffuser plate. The diffuser plate may have a plurality of spaced apart openings extending therethrough and through which fluid can flow into the chamber.

In one form, the chamber has two parts being an inlet part positioned on the inlet side of the tap seat in the chamber, and an outlet part positioned on the discharge end of the tap seat in the chamber, the inlet part having a conical wall which narrows towards the outlet, the smaller diameter valve having a valve seat which overlies the tap seat in the chamber, and a boss extending in front of the valve seat, the boss being insertable into the conical inlet part of the chamber to control the flow rate of fluid passing through the chamber.

The outlet in the chamber may comprise a plurality of separate outlets and there may be provided means to close off at least some of the outlets to control fluid flow through the insert. Thus, the means may be able

to selectively reduce the number of outlets. The means may be in the form of a body cap which will be described in greater detail below.

The internal chamber is preferably open ended at the discharge side of the tap seat in the chamber, which allows easy access to the inside of the chamber for instance to allow a jumper valve to be placed into the chamber. The chamber can be sealed by sealing engagement with a tap head of the tap or by other means.

In another form, the invention resides in an insert assembly comprising an insert having a first sealing means to sealingly engage with a tap seat in the tap, an internal chamber, an inlet to allow fluid to flow into the chamber, an outlet to allow fluid in the chamber to flow out of the insert, and a tap seat in the chamber and between the inlet and the outlet, and which separates the chamber into two parts being an inlet part positioned on the inlet side of the tap seat in the chamber, and an outlet part positioned on the discharge end of the tap seat in the chamber, the inlet part having a conical wall which narrows towards the outlet, and a valve having a valve seat which overlies the tap seat in the chamber, and a boss extending in front of the valve seat, the boss being insertable into the conical inlet part of the chamber to control the flow rate of fluid passing through the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference to the following drawings in which Figure 1 shows an insert assembly according to an embodiment of the invention.

Figure 2 shows a slight variation to the insert assembly of Figure 1.

Figures 3A and 3B illustrate a further embodiment of the invention with regard to a ratio valve.

Figures 4A and 4B illustrate a conventional standard ratio valve.

Figure 5 shows the insert of Figure 1 fitted into a conventional tap.

Figure 6 is a plan view of the insert illustrated in Figure 2.

BEST MODE Referring to the figures, there is illustrated a flow restriction insert 10 which is insertable into a conventional tap, this being best illustrated in Figure 5. Insert 10 (see Figure 1) has a first sealing means in the form of a conventional annular O ring seal 11 which fits within an annular channel 12 on a lower part of insert 10. Insert 10 is mainly hollow to define a chamber 13. Chamber 13 is in fluid communication with an inlet 14 which allows fluid (such as tap water) to flow into the chamber, and an outlet 15 which allows the fluid to flow out of the chamber. In between inlet 14 and outlet 15 is a tap seat in the form of an annular flat topped shoulder 16 on which a jumper valve 17 can be fitted.

The insert (also called reducing cylinder) is dimensioned to internally accommodate a 9mm valve 27 of the type described in our international patent application PCT/AU99/00199 which itself provides inherently better flow control than standard tap washers and jumper valves.

The insert 10 is externally dimensioned to fit within the space normally occupied by the standard 12mm jumper valve. The insert effectively scales down the internal cock dimensions by providing on one end an external seal 11 between the conventional 12mm tap seat 19 (see Figure 5) and the insert which enables an internal sealing mechanism on a reduced diameter tap seat 16 by way of the 9mm model of jumper valve described in our international patent application. The opposite open end 17 of the insert is sealed by the clamping between the tap screw 18 (Figure 5) which then forms a closed cell within the cylindrical insert and the original tap seat 19. The insert 10 is thereby locked in position over the original tap seat 19 creating a chamber 12 within the tap body. The distance between the bottom of the tap head and the original tap seat is a consistent dimension set down in the Standards and any small variation in this dimension is effectively accommodated by the flexure of the O ring seal.

While the 9mm jumper valve 27 provides better variable flow control than a 12mm valve for the purposes described above, by itself, it is not totally sufficient to achieve ideal or near ideal flow control. The insert

achieves a near ideal flow control by the addition of tangential flow primary discharge orifices 20 (forming part of inlet 14), and slots 21 as secondary discharge orifices (forming the outlet 15) Flow may be effectively restricted by simply providing a small bore radial aperture in the cylinder wall of the insert 10. This approach however creates the problem of severe cavitation caused by high pressure flow rates through a small symmetrical orifice into a larger space. This produces a loud high frequency noise which can be potentially damaging to the hearing and profoundly discomforting. In the embodiment, a tangential discharge mechanism is provided (see 20,21 Figure 1 and Figure 2). The tangential slots 21 through the cylindrical sides are more effective than the diffuser plate inlet orifices or ports 20 because of the degree of asymmetry possible at that site. The provision of tangential slots 21 discharging through the curved side of the cylinder creates orifice edges which are asymmetrical and not in the same plane. These asymmetrical exit edges prevent the creation of symmetrical turbulence and create out of phase wave forms 22 which tend to cancel each other out, which does not occur with symmetrical cavitation. The asymmetrical turbulence prevents or reduces the formation of high pressure induced symmetrical cavitation 23 (Figure 4) which forms a sound wave causing loud high frequency noise. The embodiment provides a high speed low output discharge at high pressure accompanied by very low noise, little or no more than the normal operation of an unmodified tap.

The insert 10 takes the form of a simple multiple diameter cylinder with one partially closed end (the inlet 14) (Figure 1), and one fully open end 17 through which the tap screw interacts with and controls the jumper valve. The chamber 13 has two parts being an inlet part (or conical bore) 24 on the inlet side of tap seat 16, and an outlet part (or secondary chamber) 25 on the discharge end of tap seat 16. The fully open end contains the largest internal diameter with parallel sides sufficient to accommodate the jumper valve 27 and forms the outlet part, or secondary chamber 25 (see Figure 2). Adjacent to the large internal diameter and continuous with it is a section with a reduced and tapered diameter forming

the inlet part 24 which has an internal conical section (Figure 2). This section accommodates the central locating boss 26 of a jumper valve 27 illustrated in Figure 1 which provides variable control of the flow rate. The narrow end of the conical cylinder section 24 is partially closed by a diffuser plate 28 perforated around its circumference by three equidistant small diameter holes 20 (see Figure 6). The three equidistant holes provide further flow restriction so that there is a gradient between the mains supply to the central chamber 13. Asymmetrical turbulence is enhanced by the later edges of the holes 20 in the diffuser plate 28 abutting the lower end of inlet part 24. The opposite edges of the holes which abut inlet part 24 are positioned under the conical hollow 29 within the central boss 26 of the jumper valve 27 (Figure 1). This reduces the pressure differential at all discharge points which aids in reducing cavitation noise. The three equidistant holes 20 are further modified by forming a medially rising conical surface (limited by available space) on the discharge side of the diffuser plate 28 in which the holes are located.

This has the same effect as the tangentially formed discharge slots 21 in outlet part 25 above the jumper valve and cause asymmetric turbulence which reduces cavitation noise. Cavitation turbulence is further broken up by the close proximity of the hollow conical central boss 26 of the jumper valve 27 as illustrated in Figure 1. The overall effect is to break up the powerful symmetrical cavitation effects and create pressure gradients over as many discharge points as possible to reduce the noise to acceptable limits while restricting the flow rate to the desired levels.

Below diffuser plate 28 and in the body of inlet 10 are two small steps 30 to form a locating recess for a mesh screen 31 and retaining ring 32 to prevent scale particles reaching the flow restriction discharge orifices 20, 21.

The outer diameter of the bottom of the cylinder is reduced to form a locating insert 33 (Figure 1 and Figure 5) which inserts into the bore of a normal 12mm tap. This locates the cylinder centrally in the tap body under the tap head and tap screw.

The large inside diameter of insert 10 is sufficient to permit the

normal tap screw to reciprocate in and out whilst moving the jumper valve 27 within, to and from the substitute tap seal 16 formed by the right angled step down in diameter to the smaller conical bore or inlet part 24.

The 90 degree step down to the inlet part 24 forms the reduced tap seat on which the 9mm valve seals. The inlet part 24 is tapered to conform closely with the tapered boss 26 on the jumper valve providing a good degree of primary control over the water flow by restricting the passage between the conical bore and the central boss of the jumper valve (see Figure 1). The total movement of the jumper valve from fully open to fully closed is only approximately 1-5mm, and such fine control is not possible with standard 12mm valves and taps.

The outside diameter at the top of insert 10 is reduced by half the wall thickness for a short distance to form an annular shoulder 35 onto which a body cap 36 (see Figures 1 and 6) is located. The body cap is formed with a single vertical V spline 37 on the inside diameter which interfaces with the three V grooves 38 on the body for the purposes of providing positional and volumetric settings. The purpose of body cap 36 is principally to provide a shutter mechanism which allows one to three tangential discharge slots 39 (together forming the outlet 15) to be open in stages to provide three flow rate settings. This is achieved by a large tangential slot 40 in the cap wall which, in Figure 6, is located in the lowest flow setting to expose only one of the tangential body slots 39A. The cap can be located to the other two V grooves 38 by insertion of the spline 37 into either groove 38 to allow two or three slots 39 to open simultaneously thereby achieving a stepwise increment in flow rate. The body cap 36 additionally isolates the brass or metal surfaces of the tap head from the high velocity high pressure water flow across the tangential slots with which they would otherwise make contact. Further variable flow rate regulation between the upper and lower limits for any setting of the cap is obtained by adjusting the tap screw as in the normal manner of tap operation. This provides a degree of flow control not possible with the standard 12mm screw down pattern tap.

The body cap 36 performs the additional important function of

preventing the high pressure high velocity discharging water passing through the slots from contacting the brass or metal of the tap head, which by clamping the unit in place, forms the upper limits of the secondary chamber so formed. This is necessary to prevent the formation of a corrosion groove in the brass tap head caused by the water. The fast moving water passing through the slots has the capacity to erode and or corrode the brass under these circumstances by physical and chemical effects. The cap completes a plastic lining to a) ! surfaces of the discharge slots, this therefore isolates the fast moving water from the metal which would be at greatest risk. The plastic surfaces are not significantly affected by these eroding influences.

Flow control is established by adjusting the tap handle to allow water to pass the jumper valve 27 as the primary variable control. The flow is further controlled by the tangential slots 21 through the cylinder wall, and over all flow control is achieved by the balance between these two design aspects and the primary restriction provided by the three holes 20 in the diffuser plate 28. Uniform stable flow rates of 3-9 litres per second are achievable using this system compared with 16-20 litres per second thus as much as 75% of the water may be saved without loss of functionality. These reductions apply both with and without commonly used in line ratio flow limiter valves and water saving shower heads with which the invention is compatible. To obtain AAA certification, water saving shower heads must achieve flow rates 9 litres per minute or less the invention clearly more than meets this requirement.

In practice, using water saving shower heads is not as effective as providing flow limiting control via this invention which replaces the standard 12mm jumper valve. In fact is it not necessary to use expensive water saving shower heads which are around twice the cost of a pair of inserts 10. Further, insert 10 may be fitted to any 12mm tap such as hand basins, which extends the water saving functions much more widely and more effectively than a special shower head.

Another embodiment of the principle of asymmetrical discharge geometry can be applied to a known simple ratio valve of Figure 4 which is

often used to limit flow rates in a line. The common method used is to employ a tubular component 45 with a large reduction 46 in the discharge bore such as 12mm down to 2-3mm. This is a common design which provides a single smaller central bore 46 through a closure mounted in the centre of the body of the device such as illustrated in Figure 4. This type of arrangement creates a highly symmetrical high pressure induced cavitation process 50 at the discharge end 51 of the reduced bore. This results in unacceptable levels of high frequency noise frequently sufficient to damage hearing or at least to cause considerable discomfort. This effect may also be encountered in the insert 10 if the discharge slots in the body are replace by radial holes and likewise if the three holes in the diffuser plate exist at a right angle surface on the discharge face.

The tangential discharge principle can be applied to the ratio valve by shaping the discharge surfaces 47 to provide as near as possible a tangential discharge surface. The closer the discharge orifice approaches a tangential relationship with the discharge surface the less noise is generated.

This can be further controlled by providing a larger number of smaller holes 48 eccentrically located (Figure 3) rather than a single central hole 49. The shape of the discharge surfaces 47 can be varied to provide varying degrees of asymmetry thereby further enhancing the silencing effects of asymmetrical discharge. The placement of the discharge or restriction bore 49 in an eccentric position 48 also contributes to noise reduction. Asymmetry is a major contributor to the reduction of noise in high pressure high restriction flow circuit.

It should be appreciated that various other changes and modifications may be made to the embodiments described without departing from the spirit and scope of the invention.