GB2359610A

GB2359610A - Water mixing valve

Info

Publication number: GB2359610A
Application number: GB0004674A
Authority: GB
Inventors: Colin Lander Mountford; Paul John Newcombe; Kelvin Paul Towler; James George Elcoate Smith; Daniel James Flicos
Original assignee: Aqualisa Products Ltd
Current assignee: Aqualisa Products Ltd
Priority date: 2000-02-28
Filing date: 2000-02-28
Publication date: 2001-08-29
Also published as: EP1128105A2; DE60108279D1; US20010020645A1; GB0004674D0; EP1482221B1; EP1589268A3; EP1596110A3; DE60128603D1; EP1596110A2; DE60108279T2; DE60118806T2; DE60128603T2; EP1596110B1; EP1128105B1; US6880575B2; EP1128105A3; DE60118806D1; DE60131689D1; DE60131689T2; EP1589268B1

Abstract

A water mixing valve has two inlets 2,4, a mixing chamber 12 and a control member 14 defining openings 16,18 for controlling flow between the inlets and the mixing chamber, the openings being tapered and stepped . The openings and inlets are orientated such that flows from the inlets are directed at least partly towards one another. Cup seals (50, fig 11) provided to seal with the control member, each cup seal having an axially extending annular protrusion (52). The control member has a first surface comprising a low friction material, a support 24 being provided for the control member and including surfaces for directing flows from the respective openings towards one another, support bearings 80 for the control member being provided around its periphery. The valve has a housing formed from first 8 and second 10 halves joined by a channel-shaped collar 100 zero position detector, (112, fig 15a) provided on the housing for detecting a zero position (110, fig 15a) of the control member and a temperature sensor (30, fig 15a) is provided in an outlet 6. The walls of the outlet are shaped such that the temperature sensor remains submerged in water when water is drained from the outlet. The control member may be non-planar.

Description

2359610 WATER MIXING VALVE The present invention relates to a water mixing

valve and, more particularly, to a water mixing valve having two water inlets, for instance for receiving respectively hot and cold water, and a mixing chamber for mixing flows from the two water inlets.

Previously, a large number of different designs of water mixing valves have been provided, for instance for use in shower installations.

It has been proposed to mix two water inlets using a disk shaped rotatable control member, the control member having tapered openings adjacent the water inlets. As the disk is rotated, the tapers move over the water inlets so that the open area through the disk presented to each water inlet increases or decreases according to movement of the taper. By providing the narrowest sections of the tapers end to end and the widest sections of the tapers end to end, rotation of the disk causes flow from one inlet to increase whilst flow from the other inlet decreases. This can be used to mix hot and cold water.

Unfortunately, use of tapers does not provide a linear change in water flow. In particular, with a water inlet near the widest end of the taper, small movements in the tapered opening will cause much larger changes in flow rate than similar movements at the narrowest section of the tapered opening.

Although a disk shaped control member functions effectively, the present application also considers how control members might be used to improve mixing of water from the inlets. 1 "2- In order to seal the water inlets to the control member,, it has been proposed to use cup seals which are biassed towards the surface of the control member. However. there is a problem in providing a cup seal with an appropriate sealing force for a wide range of inlet pressures.

Furthermore, there is a problem that the cup seal has to seal well with the control member, but not produce undue frictional drag on rotation of the control member.

Because the water inlets must seal with and yet move relative to the control member, there is a problem of frictional drag on the control member.

When using a disk shaped or circular plate as the control member, there is a problem in achieving good mixing of the inlet water.

When using a disk shaped or circular plate as the control member, there is a problem in correctly supporting it to allow easy rotation whilst maintaining a good seal between the water inlets and the control member.

When constructing the valve in a housing, there is a problem in joining two halves of the housing together with an effective seal and without undue expense. It has been proposed to thread the two halves together, but this can damage the internal seal and makes it difficult to achieve a predetermined orientation between the two halves. Also, clamping the two halves together can result in over compression of the seal and requires a continuous clamping force to resist any internal pressure.

Where the rotatable control member is freely rotatable continuously in one direction, it is difficult to ensure that it is correctly positioned. This is particularly important when the valve is used for controlling hot and cold water in a shower. In particular, it is very important that the shower can easily and effectively be returned to the off position and, when turned on, advanced first into the cold water supply.

Where the water mixing valve includes a temperature sensor, there is a problem that, when the valve is turned off and water drains from the valve, scale may build up on the sensor.

According to the present invention, there is provided a water mixing valve having:

two water inlets; a mixing chamber; and a control member defining respective tapered openings between the two water inlets and the mixing chamber, the tapered openings being arranged relative to the water inlets such that movement of the control is member simultaneously reduces the open area between one of the water inlets and the mixing chamber and increases the open area between the other of the water inlets and the mixing chamber wherein:

the width of each of the tapered openings is stepped at intervals corresponding to the extent of the respective inlet in the direction of movement of the control member such that the open area changes linearly with movement of the tapered opening.

In this way, linear changes in flow are achieved with respect to movement of the control member.

two water inlets; a mixing chamber; and a control member defining openings for controlling flow between the water inlets and the mixing chamber; wherein the control member is non-planar and at least partly encloses the mixing chamber and; wherein the openings and water inlets are orientated such that flow from the water inlets are directed at least partly towards one another.

In this way, the mixing chamber is at least partly provided within the control member itself such that flow from the water inlets into the io mixing chamber is at least partly opposed and, hence, mixing is improved.

two water inlets with respective cup seals; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member having a first surface against which the water inlet seal and an opposite second surface, the openings extending between the first and second surfaces; wherein each cup seal has an axially extending annular protrusion for sealing with the first surface.

In this way, the force between the cup seals and the control member will increase less as the internal pressure from the water inlets increases. Thus. the pressure between the cup seals and the control member may be kept to a minimum, thereby reducing drag on the control member. According to the present invention there is provided a water mixing valve having: 5 two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member having a first surface against which the water inlets seal and an opposite second surface, the openings extending between the first and second surfaces; wherein at least the first surface comprises a low friction material.

In this way the drag between the control member and water inlets may be minimised.

two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member comprising a substantially circular plate having first and second surfaces, the water inlets sealing against the first surface and the openings extending between the first and second surfaces; and a support for supporting the control member on the second surface 25 the support including surfaces adjacent the openings in the control -G- member for directing flows from the respective openings towards one another and into the mixing chamber for efficient mixing.

In this way, water flow from the water inlets is redirected by the support of the control member so as to improve mixing within the mixing 5 chamber.

According to the present invention there is provided a water mixing valve having:

two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member comprising a substantially circular plate having first and second surfaces, the water inlets sealing against the first surface and the openings extending between the first and second surfaces; wherein support bearings for the control member are provided close to its periphery and bearing against the second surface.

In this way, the forces on the control member exerted by the water pressure in the water inlets is absorbed directly by the bearings of the control member. Twisting of the control member and deflection of any connected shaft is thereby avoided.

According to the present invention, there mixing valve having:

is provided a water a housing formed from a first half and a second half, thefirst half including two water inlets, the second half including a water outlet and 25 the first and second halves together forming a mixing chamber; and J" a rotatable control member inside the housing for sealing with the water inlets and having openings for controlling flow from the water inlets to the mixing chamber; wherein the first and second halves have peripheral mating surfaces between which a sealing member is sandwiched; and wherein a channel- shaped collar is provided around the outer periphery of the housing to prevent the first and second halves from separating and for maintaining the first and second halves in a sealed relationship. In this way, the force required to hold the two halves of the housing together is perpendicular to the force holding the collar in place. Hence, the need for any great clamping force is removed and the two halves may easily be held together. Furthermore, since the two halves mate together in a predetermined fashion, the sealing member is not unduly compressed.

According to the present invention there is provided a water mixing valve having: two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber; and a housing for housing the water inlets, mixing chamber and rotatable control member; wherein a zero position detector is provided on the housing; and a zero position indicator is provided on the control mem ber such that when the zero position detector detects the zero position indicator, the openings are at a preselected position relative to the inlets.

-8" In this way, the relative position of the control member to the water inlets may easily be detected.

Preferably, zero position indicator is movable relative to the control member between at least two predetermined fixed positions, the predetermined fixed positions being selected according to connection of water to the water inlets.

In this way, where the mixing valve is for use with hot and cold waterP the hot and cold water can be connected arbitrarily to the two inlets and then the zero position indicator position so as to indicate the position where cold water will first be fed through the mixing valve.

According to the present invention there is also provided a water mixing valve having:

two water inlets; an outlet; and a temperature sensor in the outlet to enable electronic control of the output temperature when the two inputs are respectively hot and cold water; wherein the walls of the outlet are shaped around the temperature sensor such that, of the 6 possible orientations of the water mixing valve, in at least three perpendicular orientations, and any orientation in between, the temperature sensor remains submerged in water when water is drained from the outlet.

In this way, when the water mixing valve is turned off, the temperature sensor will remain submerged in water so that scale is less likely to build up.

-g- The invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings, in which:

Figure 1 illustrates a valve embodying the present invention; Figures 2(a) and (b) illustrate cross-sections through the valve of Figure 1; Figures 3(a) and (b) illustrate control members for use in the valve of Figure 1; Figure 4 illustrates a stepped tapered opening for use in a control member; Figures 5(a) and (b) illustrate inserts for use with the control member; Figure 6 illustrate an insert in the valve; Figure 7 illustrates an asymmetric control member; Figures 8(a) and (b) illustrate linear control members; Figure 9 illustrates a cylindrical control member with stepped tapered openings; Figure 10(a) to (c) illustrate control members which at least partially enclose a mixing chamber; Figure 11 illustrates a cup seal for use in the valve of Figure 1; Figure 12 illustrates a cross-section through the cup seal of Figure 11; Figures 13(a) and (b) illustrate a control member and its support; Figure 14 illustrates the upper housing of the valve of Figure 1; Figures 1 5(a) and (b) illustrate the upper housing of the valve of Figure 1 with the servo assembly removed; Figures 16(a) and (b) illustrate cross-sections through the valve of Figure 1 showing the temperature sensor; Referring to Figure 1, there is shown a water mixing valve having a first inlet 2, a second inlet 4 and an outlet 6.

As illustrated in Figures 2(a) and (b), the water mixing valve includes a housing made up of a first half 8 and a second half 10 which together define a mixing chamber 12. Thus, in use, water passes into the mixing valve from the water inlets 2 and 4, is mixed together within the mixing chamber 12 and then passes out of the outlet 6.

In order to control the ratio of water mixed from the first and second inlets 2A, a control member 14 is provided adjacent the ends of the water inlets 2,4 and separating the water inlets 2,4 from the mixing chamber 12.

As illustrated in Figures 3(a) and (b), the control member 14 is a is plate having first and second tapered openings 16,18.

The water inlets 2,4 seal against a first surface 20 of the control member 14. The control member 14 may then be rotated so as to bring the opening 16,18 in line with the water inlets 2,4 and control the proportion of water entering the mixing chamber 12.

A second surface 22 of the control member 14 faces the mixing chamber 12. A support 24 abuts the second surface 22 of the control member 14. Formed integrally with the support 24 is a shaft 26 by which the support 24 and control member 14 may be rotated.

As illustrated in Figure 1, a motor 28, such as a stepper motor is provided to rotate the shaft and, hence, the control member 14. In other constructions, the shaft 26 could be rotatable via a manual mechanism.

Also illustrated in Figure 1 is the rear connection portion of a temperature sensor 30. The temperature sensor 30 or at least its tip is located in the mixed flow of water and. when the water inlets 2 and 4 are used respectively for hot and cold water, the information derived from the temperature sensor 30 can be used to control the motor 28 and, hence, the position of the control member 14 and the temperature of the mixed flow of outlet water.

Figures 3 (a) and (b) illustrate two different control members 14 for use in the valve. In particular, Figure 3 (a) illustrates a control member 14 having tapered openings 16 and 18 which are stepped with generally parallel sides. In contrast, the control member 14 of Figure 3(b) has tapered openings which taper continuously from their widest ends to their narrowest ends.

The present application recognises for the first time that using a control member such as that illustrated in Figure 3(b) with standard water inlets results in a non-linear change in flow with respect to rotation of the control member. In particular, water flow from a water inlet is determined by the open area presented to it by a corresponding tapered opening in the control member. In this respect, movement of the tapered opening relative to the water inlet will not result in a linear change in open area. Towards the narrow end of the tapered opening, a given movement will result in a relatively small change in open area, whereas, towards the wider end of the tapered opening, the same given movement will result in a larger change in open area.

By providing stepped tapered openings as illustrated in Figure 3(a), this problem can be overcome.

As illustrated in Figure 4, the intervals between steps corresponds to the extent of the water inlet in the direction of movement of the control member. Thus, as the water inlet moves from position A to position B, the open area presented to the water inlet (and through which water may flow into the mixing chamber 12) increases linearly with movement. In order to maintain this linear increase, a step is provided in the opening 16. In fact, the total step is provided symmetrically on the opening 16 by virtue of two steps 32a and 32b.

The total step provided by the steps 32a and 32b has a width equal to the narrowest section 32 of the opening 16. The next section 34 in the opening 16 then again has generally parallel sides. In this way, as the water inlet moves from position B to position C, the open area presented to the water inlet again increases linearly and, furthermore, increases linearly at the same rate as the narrowest section 32. The opening 16 includes a series of pairs of symmetric steps, each pair having a width equal to the width of the narrowest section 32. In this way, from the narrowest section 32 to the widest section 36. movement of the opening 16 relative to the water inlet provides a linearly increasing open area and, hence, linearly increasing flow.

Where5 as illustrated, the water inlets are circular, it is possible to provide a circular section 38 as part of the widest section 36. In this way, full opening of the water inlet can be achieved so as to ensure maximum flow.

As an alternative to the above, the control member 14 of Figure 3(b) can be used together with inserts 40 in the water inlets 2 and 4. A suitable insert is illustrated in Figures 5(a) and (b). The insert may be fitted in the valve as illustrated in Figure 6. The inserts 40 substantially fill the cross-section of the inlets and are provided with a slot-like opening 42. In particular, the inserts 40 are positioned in the inlets 2 and 4 so as to present their slotted openings 42 adjacent the tapered openings 16A8 of the control member 14. Furthermore,, the slotted openings 42 are orientated perpendicular to the direction of movement of the tapered openings 16,18. Thus, in the illustrated embodiment, the slotted openings 42 are orientated in a radial direction relative to the valve and control member 14.

By using water inlets 2,4 having slotted cross-sections, the increase in open cross-sectional area into the mixing chamber 12 is approximately proportional to the width of the tapered openings 16,18 presented to the water inlet. Thus, mixing of the water from the water inlets 2,4 is approximately proportional to movement of the valve and control member 14.

Use of the slotted openings is particularly advantageous for systems having large differences in pressure between the two inlets. For instance, when used with combi heaters, cold to hot water pressure can have a ratio as much as 33: 1.

Referring again to Figures 3(a) and (b), it will be seen that the widest sections 36 of the openings 16,18 are positioned closer to one another than the narrowest sections 32. This enables the control member 14 to turn to a position at which one of the openings 16,18 provide maximum open area to one of the water inlets 2,4 whilst the other of the water inlets 2,4 is still fully closed. By providing a good seal between the water inlets and the sealing surface of the control member 14, this -14enables the mixing valve to provide maximum flow from one of the inlets 254 whilst closing offthe other inlet 2,4. This is a significant advantage over previous valve arrangements which, when positioned for maximum flow from one inlet, allow a slight flow from the other inlet. For arrangements where the mixing valve mixes hot and cold water, the arrangement of Figures 3(a) and (b) allows either maximum hot or maximum cold to be selected.

In order to maintain maximum flow through the mixing valve, the openings 16,18 are positioned relative to one another accordingly. In the illustrated arrangement, the water inlets 2,4 are diametrically opposed across the axis of rotation of the control member 14. This enables the control member 14 to operate symmetrically in either direction.

Upon rotation of the control member 14 the following operation is preferred. The control member 14 is rotated clockwise as illustrated in Figure 3 such that the first inlet 2 is exposed to the widest section 36 of the opening 16. At this time, the second inlet 4 is still closed by the control member 14. Upon further rotation of the control member 14, simultaneously, as the next narrower section of the first opening 16 moves over the first inlet 2 and progressively restricts its flow, the narrowest section 32 of the second opening 18 moves across the second inlet 4 and progressively increases the flow from this inlet by the same amount. Eventually, upon further rotation of the control member 14, the second inlet 4 reaches the widest section 36 of the second opening 18 to allow maximum flow from the second inlet 4, whilst the first inlet 2 is closed by the control member 14. Of course, further rotation of the control member 14 will then open the second inlet 4 with the first As- opening 16. Also, anti-clockwise rotation of the control member 14 will have a similar effect.

As an alternative,, instead of providing symmetric operation of the control member 14, it is possible to position the tapered opening 16,18 in the control member 14 such that one of the tapered openings 16,18 can provide full and unmixed flow.

It will be appreciated that during normal start-up, the control member 14 will be rotated through the full-cold position then through the mixing positions with progressively more hot water until a desired temperature is achieved. Thus, by providing the full cold position, the mixer valve provides an unnecessary amount of cold water to the outlet during start-up. For this reason, it is proposed that, for the normal direction of rotation of the control member 14 for start-up, the control member will move directly from the off position to a mixing position.

To achieve this, it is sufficient for the tapered opening 16,18 to be spaced apart at the widest section by the size of the inlets and at their narrowest sections by twice the size of the inlets, the spacing between the narrower sections of the tapered opening 16,18 being non-symmetrically positioned. A suitable control member is illustrated in Figure 7.

By this arrangement, should the user particularly require the full cold position, the control member 14 can be rotated from the off position in an opposition direction so as to make use of the maximum flow position of the other tapered opening 16,18.

With respect to the stepped tapered openings, these can, of course, be applied to other types of control member. For instance, as illustrated in Figures 8(a) and (b), the openings can be arranged in a plate for linear motion. Similarly, as illustrated in Figure 9, they can be located in a cylindrical control member.

Following on from Figure 9, Figures 1 0(a), (b) and (c) illustrate various forms of non-planar control members which at least partly enclose the mixing chamber. The particular illustrated examples are respectively cylindrical, conical and hemispherical. These arrangements are particularly advantageous since the water inlet flows are naturally at least partly opposed. Hence, water inlet flows passing through the openings of the control member will naturally mix with one another before leaving the mixing chamber without any special features for creating mixing within the chamber.

Figure 11 illustrates the sealing components at the ends of each of the water inlets 2A. A cup seal 50 is provided internally with a coil spring 5 1. The cup spring 50 seals with the inner periphery of an inlet 2,4 and is sprung forwardly by the coil spring 51 so as to maintain a seal with the control member 14.

As explained above, it is important that the water inlets seal effectively with the first surface 20 of the control member 14. In particular; when the control member 14 is in the position in which both inlets are shut off, the cup seals 50 must effectively seal with the control member 14. Furthermore, they may remain in this position for a considerable amount of time. In view of thisP the springs provide a strong sealing pressure between the cup seals 50 and the control member 14.

If the control member 14 did not move, this arrangement would be quite satisfactory using conventional cup seals. However, according to the illustrated arrangement, in order to reduce the number of parts and simplify operation, the cup seals 50 seal directly onto the moving control member 14. There is then a problem with using cup seals. In particular, with a large inwardly extending sealing surface, good sealing is achieved. but there is significant friction between the sealing surface and the control member 14. This causes resistance to rotation of the control member 14 and also induces wear on the cup seal. On the other hand, by reducing the inwardly extending sealing surface of the cup seal, insufficient pressure is produced between the sealing surface and the control member 14. There is an additional problem that inlet pressures can vary considerably depending on the particular installation. Mains water supply in the U.K. can reach 16 bar though is supplied to houses with 12 bar pipe. However, in practice, in a domestic installation, pressure might vary from 0. 1 bar to 10 bar, some boiler manufactures specifying that all fittings must be specified to 10 bar.

Hence, the cup seal 50 is required to provide a good sealing force for a variety of different pressures, but without creating undue frictional forces with the control member 14.

As illustrated in Figure 12, the cup seal includes an annular protrusion 52 extending from what would have otherwise been the inwardly extending sealing surface 54.

The annular protrusion 52 thus forms the main seal with the control member 14. However, the inwardly extending sealing surface 54 will also provide some sealing effect together with the annular protrusion 52.

By providing the annular protrusion 52, however, a space 56 is formed under the inwardly extending portion 54. This space 56 helps to accommodate variations in water pressure and reduce ffictional drag between the cup seal 50 and the control member 14. In particular, water is able to feed into the space 56 under the inwardly extending portion 54. Thus,, in this way, as the water pressure in the inlet increases, there is an increase in pressure in the space 56 under the inwardly extending portion 54 which will counteract the effect of the pressure forcing the cup seal 50 onto the control member 14. In this way, as the water pressure in the inlet increases,- the force between the cup seal 50, in particular the annular protrusion 52, and the control member 14 does not increase as much. Thus, a more constant sealing force may be provided between the cup seal 50 and the control member 14. The sealing force may therefore be kept towards its minimum so as to minimize the drag between the cup seals 50 and the control member 14.

The cup seals 50 may additionally be coated with a low friction material such as PTFE.

As described above and illustrated in Figure 2(a), the inlets 2 and 4 seal directly with the control member 14. This is advantageous, since it requires a reduced number of parts and is of a simple construction. However, as mentioned above, there are problems in providing a good seal between the inlets 2,4 and the control member without producing undue drag and wear between seals of the inlets 2,4 and the control member 14.

It is proposed to construct the control member 14 of FEP, an injectionmoulding grade of PTFE. It is also possible to use any potable -19water safe low friction material such as PTFE itself, Molybdenum loaded PTFE, PTFE or Molybdenum Loaded Acetal. Alternatively, a ceramic part could be used.

The control member 14 must allow for a space behind its surface 22 to form the mixing chamber 12. Furthermore, means are required to rotate the control member 14. It is not possible to provide a control member 14 made from one of the materials mentioned above and which is of sufficient strength. It would be possible to provide such friction reducing materialsembedded in other materials, but the friction reducing properties are thereby compromised.

It is proposed to provide a separate support structure such as illustrated in Figures 2(a) and (b). It might be possible to coat such a support structure with a suitable friction reducing material as mentioned above. However, for ease and reduced cost of production, it is desired to construct the support structure 24 from a plastics material. In this respect, it is not possible or is at least extremely difficult to coat a suitable plastics material with a suitable friction reducing material, because of the heat requirements. Therefore, it is proposed to provide the control member 14 as a self-supporting component which is then additionally supported by the support structure 24 to withstand the additional forces experienced during use. The control member 14 may be attached to the support structure 24 in any appropriate way. Indeed, a previously constructed self-supporting control member 14 may be inserted into the mould of the support structure 24 such that the support structure 24 is then moulded integrally with the control member 14 by a process of insert moulding.

In this way, materials appropriate for giving the control member 14 appropriate strength can be used for the support structure 24, whilst the surface 20 of the control member 14 may be made of an appropriate material to reduce friction and wear with the inlets 2,4. This may be particularly important when the support structure 24 is also integrally formed with the shaft 26, since the shaft 26 must transmit any torque required to rotate the control member 14.

Figures 13(a) and (b) illustrate the support structure 24 and shaft 26, together with a control member 14.

The support structure 24 includes a support surface 60 against which the second surface 22 of the control member 14 abuts. As explained above, the control member 14 could be formed integrally with the support structure 24. However, as illustrated, protrusions 62 are provided to engage in recesses 63 in the control member 14 so that the control member 14 may be pressed against the support structure 24 and fixed rotationally.

The support structure 24 includes orifices 64,66 corresponding to the tapered openings 16,18, the orifices 64,66 may be larger than the opening 16,18, but should be sufficiently close in size so as to provide mechanical support.

As illustrated, shaft 26 takes the form of a hollow cylinder having outlet apertures 70 at its end furthest from the control member 14.

Thus, water flowing through tapered openings 16 and 18 passes through the orifices 64,66 into the mixing chamber 12 defined by the support structure 24 and hollow shaft 26. The mixed water then passes out of the outlet apertures 70 and into the chamber 72 defined by the first half 8 and illustrated in Figure 2(a). From the chamber 72, the mixed water then flows out from the outlet 6.

As illustrated in Figures 13(a) and (b), annular walls 74 extend inwardly of the mixing chamber 12 from the support surface 60 of the support structure 24. These annular walls 74 extend to a face 76 of the support structure 24 around the periphery of the hollow opening of the shaft 26. In this way, the inner section of the support surface 60 of the support structure 24 is additionally supported, thereby reducing its tendency to flex under high inlet water pressures.

As illustrated, the annular wall 74 include breaks 78 allowing flow of water through to the hollow shaft 26. In this way, water cannot flow directly from the tapered opening 16,18 into the shaft 26. The water mustfirst flow around parts of the annular wall 74. This assists in mixing. Furthermore, when the water then flows through the breaks 78 in the annular walls 74, flows of water are directed towards one another5 thereby further increasing mixing.

It is possible to introduce further features on the breaks 78 or within the inner walls of the shaft 26 so as to further encourage mixing.

In order to rotatably mount the control member 14, it was considered to provide bearings around the shaft 26. However, because the water inlets 2,4 seal directly with the control member 14 and because the control member 14 divides the water inlets 2,4 from the mixing chamber 12. there are significant problems in this.

Firstly, the pressure exerted by the water inlets 2,4 is towards the outer periphery of the control member 14 and, hence the control member 14 tends to deflect. Furthermore, the inlet pressures at the water inlets -222,4 may be substantially different. Indeed, this will naturally occur when the control member 14 is set so as to allow a lot of flow through one inlet and a little flow through the other inlet.

In order to overcome these problems, as illustrated in Figures 2(a) and (b), bearings 80 are provided towards the outer periphery behind the second surface 22 of the control member 14. In particular, in the illustrated embodiment the bearings 80 bear against the back of the support structure 24.

Preferably, the bearings are formed as a ball race and are illustrated in Figure 14 which shows the open side of the first half 8 of the housing.

Hence,, the force exerted by the water inlets 2,4 on the control member 14 are directed straight through the support structure 24 onto the bearings 80. In this way, it is not necessary to provide particularly strong components for the support structure 24 and shaft 26 to avoid twisting. Forces are transmitted without any twisting occurring to the control member 14 and its associated parts.

As mentioned above. the housing is formed of a first half 8 and a second half 10. Clearly, it is necessary to assemble these two halves together in such a manner that they seal correctly.

It might be possible for the first half 8 and second half 10 to be screwed together by means of threads on the respective halves. However, it would then be very difficult to ensure correct rotational alignment between the first and second halves when they had been fully rotated and tightened into a sealing engagement.

It might also be possible to provide an 0-ring around an outer periphery of one half to seal with an inner periphery of the other half. However, 0rings are provided in grooves or channels. In this respect, in order to mould a suitable 0-ring channel in an outer periphery of one of the first and second halves, it is necessary to use a mould which separates along a line running through the 0-ring channel. In practice, this inevitably results in a slight ridge in the moulded plastic, thereby potentially damaging the 0-ring itself or at least affecting its sealing properties.

In order to overcome these problems, as illustrated in Figures 2(a) and (b) and 14, the first half includes a step 90 into which an 0-ring 92 is fitted. The first half also includes a lip 94. As illustrated in Figures 2(a) and (b), the second half 10 of the housing includes an outwardly extending flange 96 at the end of which there is an axially extending flange 98. As also illustrated in Figures 2(a) and (b), the outwardly extending flange 96 and axially extending portion 98 of the second half 10 mate with the lip 94 of the first half 8. This mating is arranged such that the 0-ring 92 is squeezed by the correct amount to achieve the required sealing. In particular, with the first and second halves 8,10 held in this position, correct sealing is achieved.

By this arrangement, it will also be noted that the join between the moulds for producing the first half 8 may run around a radial periphery of the first half 8, for instance around the edge of lip 94. In this way, the seating of the 0-ring 92 need not be disturbed.

In order to hold the first and second halves 8,10 in this position, a collar 100 is provided.

The collar 100 fits around the lip 94 of the first half 8 and the portions 96, 9 8 of the second half 10 so as to prevent them from separating. By using a collar of a rigid material, there is no need to provide any squeezing force between the first and second halves 8, 10.

The collar merely holds the first and second halves 8, 10 together in the correct position so that the 0-ring 92 provides the correct sealing force. The force holding the collar 100 in place is radially inwardly of the lip 94 and portions 96, 98. Hence, the force is perpendicular to the that needed to hold the first and second halves 8. 10 together. Hence, no great force is required to hold the collar 100 in place, but, with the collar in place, it can withstand considerable forces resulting from internal pressure trying to separate the first and second halves 8, 10.

As illustrated,- it is also possible for the cross-section of the collar 100 to have inner support surfaces 102,104 which diverge slightly. The is lip 94 of the first half 8 and the outwardly extending flange 96 of the second half 10 are angled by a corresponding amount. In this way, when the internal water pressure tries to separate the first and second halves 8,10 some of the axial separating force is transferred by means of the diverging surfaces to an outward radial force. In this way, the strength of the cross-section of the collar 100 need not be the limiting factor in holding the first and second halves together. By increasing the strength of the collar 100 around its periphery, increased internal pressures may be resisted. This may be achieved, for instance, by tightening a metal band around the outer periphery of the collar 100.

Hence, use of the collar 100 holding first and second halves 8, 10 together provides a simple and highly effective sealing arrangement. No undue pressure is exerted on the 0-ring 92 and no components are required to be threaded together. In this respect, it will be noted that rotating the first and second halves 8, 10 relative to one another to engage a thread might twist and damage the 0-ring 92.

As illustrated in Figures 15(a) and (b), the shaft 26 includes a zero position indicator 110. The position of the zero indicator 110 around the periphery is so as to indicate the position of the control member 14 within the valve housing. In particular, a zero detector 112 is provided on the housing such that whenever the zero position indicator 110 actuates the zero position detector 112, an associated control system can determine the position of the control member. Preferably, actuation on the zero position detector 112 indicates the fully shut off position of the valve.

In this way, the motor 28 can merely rotate the control member 14 continuously until the zero position detector 112 is actuated such that the system then knows that this is the shut off position.

The zero position indicator 110 and zero position detector 112 may be embodied in a number of different ways. In particular, a cam may be provided on or connected to the shaft 26 in conjunction with a micro switch on the housing. Alternatively, the zero position detector may be a photo detector responding to some marking or protrusion connected to the shaft 26.

When connecting the inlets 2, 4, it is often essential to ensure that the inlets 2,, 4 are connected to the correct water supplies. In particular, when mixing valves are used to mix hot and cold water, it is usually essential that a particular inlet be connected to the hot water supply.

Indeed. referring to Figures 3(a) and (b), it will be noted from the above description that, rotating the control member 14 clockwise to provide the opening 16 adjacent a water inlet, the system will always expect to be turning on either the cold or the hot water supply. For domestic use with showers for example, it is essential that, upon opening the valve, the valve always opens the cold water supply first and then mixes in hot water.

Usually, if an installer connects the water inlet incorrectly, where the valve attempts to open the cold water inlet and receives hot water,, it will automatically shut off and, hence, the valve will not be operable.

By using the zero position indicator 110 and zero position detector 112, this can be overcome.

In particular, if the water inlets are incorrectly connected, such that the valve fails to operate, it is not necessarily to change the water connection. Instead, one or other of the zero position indicator and zero position detector can be moved to an opposition position relative to the shaft 16 and control member 14. In this respect, Figures 15(a) and (b) illustrate the repositioning of the zero position detector 112. In this way, for the illustrated embodiment the opposite position will be an opposite diametric position relative to the shaft 16 and control member 14 and the control system will view the shut off position as being 180 degrees from the current position and will reset the control member 14 to that new position. Of course, with other arrangements, the shut off position may be some other angle from the current position. From the new position, rotation of the control member 14 will first open the cold water supply as expected.

Rather than move the zero position detector on the housing, it is also possible to provide two diametrically opposed zero position detectors. In this case. the appropriate detector can be connected manually by the user according to observed operation of the valve.

Alternatively, the control system could automatically enable the zero position detector which provides current functioning of the valve.

It will be appreciated that the principle of using a zero position indicator and detector or detectors and moving/switching them can be applied to other arrangements of control member, such that the movement will not always be diametric. For instance, for linear arrangements such as illustrated in Figures 8(a) and (b) the indicator or detector would be moved from one end of travel to the other. However, the principle is particularly advantageous with the illustrated embodiment where the control member 14 is able to continuously rotate in one direction through all modes of operation.

As mentioned above, the valve may include a temperature sensor 3 0 for sensing the temperature of the water mixed from the inlet valves 2 and 4.

When the valve is shut off, it is possible for water to drain out of the mixing chamber 12 and outlet 6. Hence, components within the valve may dry, leaving scale behind. This can be particularly damaging to temperature sensors such as thennistors.

As illustrated in Figures 16(a) and (b), the housing of the valve is arranged such that the active part of temperature sensor 30 extends into a portion of the valve housing which will retain water after water is drained out of the valve housing through the outlet 6.

Referring to Figure 16(a), it will be seen that the tip of the temperature sensor 30 lies below the outlet 6. This is clearly true for all orientations represented by Figure 16(a) with the outlet 6 horizontal and above the temperature sensor 30.

Referring to Figure 16(b), it will be seen again that with the outlet 6 orientated vertically above the valve, the temperature sensor 30 or at least its tip, will remain submerged in water when water is drained from the valve housing through the outlet 6.

Thus,, in this way, by keeping the temperature sensor or at least its tip submerged, scale will be less prone to building up on the temperature sensor 30 and its life will be greatly increased.

In general, the valve will be provided in some form of generally rectangular housing for installation in a building. Hence, the valve 30 is arranged in the valve housing such that with the valve mounted within the casing, of the six possible orientations of the casing, in three perpendicular orientations, the temperature sensor 30 will remain immersed in water.

It will be appreciated with the particular illustrated embodiment, the temperature sensor 30 will also remain submerged for orientations between those three perpendicular orientations.

As illustrated in Figure 16, the housing of the valve is arranged such that the temperature sensor 30 or at least its tip extends into a recessed portion 120. This recessed portion 120 is arranged such that in three perpendicular orientations and the orientations between them, when water is drained from the valve housing, a small pocket of water will remain in the recess 120 keeping the temperature sensor 30 submerged.

In this way, scale will be less prone to building build up on the temperature sensor 30 and its life will be greatly increased.

In general, the valve will be provided in some form of generally rectangular housing for installation in a building. Hence, the recess 120 is provided such that with the valve mounted within the casing, of the six possible orientations of the casing, in three perpendicular orientations, the temperature sensor 30 will remain emersed in water.

Claims

1. A water mixing valve having:

two water inlets; a mixing chamber; and a control member defining respective tapered openings between the two water inlets and the mixing chamber, the tapered openings being arranged relative to the water inlets such that movement of the control member simultaneously reduces the open area between one of the water inlets and the mixing chamber and increases the open area between the other of the water inlets and the mixing chamber wherein: the width of each of the tapered openings is stepped at intervals corresponding to the extent of the respective inlet in the direction of movement of the control member such that the open area changes linearly with movement of the tapered opening.

2. A water mixing valve according to claim 1 wherein the control member is disc-shaped and the two tapered openings are formed generally along a circular path with their narrowest sections adjacent one another..

3. A water mixing valve having:

two water inlets; a mixing chamber; and a control member defming openings for controlling flow between the water inlets and the mixing chamber; wherein the control member is non-planar and at least partly encloses the mixing chamber and; wherein the openings and water inlets are orientated such that flow from the water inlets are directed at least partly towards one another.

4. A water mixing valve according to claim 3 wherein the control member is cylindrical and the water inlets face radially inwardly 5 with respect to the cylindrical control member.

5. A water mixing valve according to claim 3 or 4 wherein the openings comprise respective tapered openings between the two water inlets and the mixing chamber, the tapered openings being arranged relative to the water inlets such that movement of the control member simultaneously reduces the open area between one of the water inlets and the mixing chamber and increases the open area between the other of the water inlets and the mixing chamber, the width of each of the tapered openings being stepped at intervals corresponding to the extent of the respective inlet in the direction of movement of the control member such that the open area changes linearly with movement of the tapered opening.

6. A water mixing valve according to claim 1, 2 or 5 wherein, between steps, the tapered openings have substantially parallel sides.

7. ' A water mixing valve according to any one of claims 1, 2, 5 and 6 wherein the width of each tapered opening is stepped by means of substantially symmetric steps on either side of the tapered opening.

8. A water mixing valve according to any one of claims 1, 2 and 5 to 7 wherein the width of each tapered opening is stepped by an amount equal to the width of the narrowest section of the tapered opening.

1 9. A water mixing valve according to any one of claims 1, 2 and 5 to 8 wherein the widest sections of the two tapered openings are spaced apart by at least the extent of the inlets and the narrowest sections of the two tapered openings are spaced apart by at least 3 times the extent of the inlets such that each of the inlets may be fully opened to the mixing chamber with the other inlet fully closed. 10. A water mixing valve having: two water inlets with respective cup seals; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member having a first surface against which the water inlet seal and an opposite second surface,, the openings extending between the first and second surfaces; wherein each cup seal has an axially extending annular protrusion for sealing with the first surface.

11. A water mixing valve according to claim 10 wherein the annular protrusion is spaced outwardly from the inner periphery of the cup seal. ' 12. A water mixing valve according to claim 10 or 11 wherein the cup seals are coated with PUE.

13. A water mixing valve having:

two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member having a first surface against which the water inlets seal and an opposite second surface, the openings extending between the first and second surfaces; wherein at least the first surface comprises a low friction material.

14. A water mixing valve according to claim 13 wherein the low friction material is one of FEP5 PTFE,, Molybdenum loaded PTFE, PTFE loaded Acetal and Molybdenum loaded Acetal.

15. A water mixing valve according to claim 13 or 14 wherein the control member comprises a base structure and the low ffiction material forms a layer on the base structure.

16. A water mixing valve according to claim 15 wherein the control member rotates on a shaft and the base structure is integral with the shaft.

17. A water mixing valve having:

two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member comprising a substantially circular plate having first and second surfaces, the water inlets sealing against the first surface and the openings extending between the first and second surfaces; and a support for supporting the control member on the second surface,the support including surfaces adjacent the openings in the control member for directing flows from the respective openings towards one another and into the mixing chamber for efficient mixing.

18. A water mixing valve according to claim 17 wherein the control member rotates on a shaft and the shaft passes through the support and mixing chamber, the shaft having on its outer periphery in the mixing chamber surfaces for encouraging mixing in the mixing 5 chamber.

19. A water mixing valve having:

two water inlets; mixing chamber; rotatable control member having openings for controlling flow from the water inlets to the mixing chamber, the control member comprising a substantially circular plate having first and second surfaces, the water inlets sealing against the first surface and the openings extending between the first and second surfaces; wherein support bearings for the control member are provided close to its periphery and bearing against the second surface.

20. A water mixing valve having:

a housing formed from a first half and a second half, the first half including two water inlets, the second half including a water outlet and the first and second halves together forming a mixing chamber; and a rotatable control member inside the housing for sealing with the water inlets and having openings for controlling flow from the water inlets to the mixing chamber; wherein the first and second halves have peripheral mating surfaces between which a sealing member is sandwiched; and wherein a channel-shaped collar is provided around the outer periphery of the housing to prevent the first and second halves ftom separating and for maintaining the first and second halves in a sealed relationship.

2 1. A water mixing valve according to claim 20 having a peripheral recess, the sealing member comprising a resilient annular seal fitted in the recess and the peripheral mating surfaces being arranged such that the annular seal is compressed by a predetermined amount when the mating surfaces engage one another.

22. A water mixing valve having:

two water inlets; a mixing chamber; a rotatable control member having openings for controlling flow from the water inlets to the mixing chamber; and a housing for housing the water inlets, mixing chamber and rotatable control member; wherein a zero position detector is provided on the housing; and a zero position indicator is provided on the control member such that when the zero position detector detects the zero position indicator, the openings are at a preselected position relative to the inlets.

23. A water mixing valve according to claim 22 wherein the zero position indicator comprise a cam on the shaft of the control member and the zero position detector comprise a microswitch.

24. A water mixing valve according to claim 23 wherein the zero position indicator is movable relative to the control member between at least two predetermined fixed positions, the predetermined -36fixed positions being selected according to connection of water to the water inlets.

25. A water mixing valve according to claim 22, 23 or 24 comprising at least two zero position detector at predetermined positions relative to the water inlets and selectable according to how water is connected to the water inlets.

26. A water mixing valve having:

two water inlets; an outlet; and a temperature sensor in the outlet to enable electronic control of the output temperature when the two inputs are respectively hot and cold water; wherein the walls of the outlet are shaped around the temperature sensor such that of the 6 possible orientations of the water mixing valve, in at least three perpendicular orientations and any orientation in between, the temperature sensor remains submerged in water when water is drained from the outlet.

27. A water mixing valve according to claim 26 having an outer housing arranged for mounting on a wall or floor in said at least three perpendicular orientations.

28. A water mixing valve having in combination the features of one or more of 1) any one of claims 1 to 9, 2) claim 10, 11 or 12, 3) any one of claims 13 to 16, 4) claim 17 or 18, 5) claim 19, 6) claim 20 or 21, 7) any one of claims 22 to 25 and 8) claim 26 or 27.

30. A water mixing valve constructed substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.